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Open AccessEditor’s ChoiceArticle
Fatty Acid-Treated Induced Pluripotent Stem Cell-Derived Human Cardiomyocytes Exhibit Adult Cardiomyocyte-Like Energy Metabolism Phenotypes
Cells 2019, 8(9), 1095; https://doi.org/10.3390/cells8091095 - 17 Sep 2019
Cited by 21
Abstract
Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs) (iPSC-CMs) are a promising cell source for myocardial regeneration, disease modeling and drug assessment. However, iPSC-CMs exhibit immature fetal CM-like characteristics that are different from adult CMs in several aspects, including cellular structure and metabolism. [...] Read more.
Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs) (iPSC-CMs) are a promising cell source for myocardial regeneration, disease modeling and drug assessment. However, iPSC-CMs exhibit immature fetal CM-like characteristics that are different from adult CMs in several aspects, including cellular structure and metabolism. As an example, glycolysis is a major energy source for immature CMs. As CMs mature, the mitochondrial oxidative capacity increases, with fatty acid β-oxidation becoming a key energy source to meet the heart’s high energy demand. The immaturity of iPSC-CMs thereby limits their applications. The aim of this study was to investigate whether the energy substrate fatty acid-treated iPSC-CMs exhibit adult CM-like metabolic properties. After 20 days of differentiation from human iPSCs, iPSC-CMs were sequentially cultured with CM purification medium (lactate+/glucose-) for 7 days and maturation medium (fatty acids+/glucose-) for 3–7 days by mimicking the adult CM’s preference of utilizing fatty acids as a major metabolic substrate. The purity and maturity of iPSC-CMs were characterized via the analysis of: (1) Expression of CM-specific markers (e.g., troponin T, and sodium and potassium channels) using RT-qPCR, Western blot or immunofluorescence staining and electron microscopy imaging; and (2) cell energy metabolic profiles using the XF96 Extracellular Flux Analyzer. iPSCs-CMs (98% purity) cultured in maturation medium exhibited enhanced elongation, increased mitochondrial numbers with more aligned Z-lines, and increased expression of matured CM-related genes, suggesting that fatty acid-contained medium promotes iPSC-CMs to undergo maturation. In addition, the oxygen consumption rate (OCR) linked to basal respiration, ATP production, and maximal respiration and spare respiratory capacity (representing mitochondrial function) was increased in matured iPSC-CMs. Mature iPSC-CMs also displayed a larger change in basal and maximum respirations due to the utilization of exogenous fatty acids (palmitate) compared with non-matured control iPSC-CMs. Etomoxir (a carnitine palmitoyltransferase 1 inhibitor) but not 2-deoxyglucose (an inhibitor of glycolysis) abolished the palmitate pretreatment-mediated OCR increases in mature iPSC-CMs. Collectively, our data demonstrate for the first time that fatty acid treatment promotes metabolic maturation of iPSC-CMs (as evidenced by enhanced mitochondrial oxidative function and strong capacity of utilizing fatty acids as energy source). These matured iPSC-CMs might be a promising human CM source for broad biomedical application. Full article
(This article belongs to the Special Issue Stem Cell-based Therapy and Disease Modeling)
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Open AccessEditor’s ChoiceArticle
Melatonin Effects on Non-Alcoholic Fatty Liver Disease Are Related to MicroRNA-34a-5p/Sirt1 Axis and Autophagy
Cells 2019, 8(9), 1053; https://doi.org/10.3390/cells8091053 - 08 Sep 2019
Cited by 12
Abstract
Melatonin, an indole produced by pineal and extrapineal tissues, but also taken with a vegetarian diet, has strong anti-oxidant, anti-inflammatory and anti-obesogenic potentials. Non-alcoholic fatty liver disease (NAFLD) is the hepatic side of the metabolic syndrome. NAFLD is a still reversible phase but [...] Read more.
Melatonin, an indole produced by pineal and extrapineal tissues, but also taken with a vegetarian diet, has strong anti-oxidant, anti-inflammatory and anti-obesogenic potentials. Non-alcoholic fatty liver disease (NAFLD) is the hepatic side of the metabolic syndrome. NAFLD is a still reversible phase but may evolve into steatohepatitis (NASH), cirrhosis and carcinoma. Currently, an effective therapy for blocking NAFLD staging is lacking. Silent information regulator 1 (SIRT1), a NAD+ dependent histone deacetylase, modulates the energetic metabolism in the liver. Micro-RNA-34a-5p, a direct inhibitor of SIRT1, is an emerging indicator of NAFLD grading. Thus, here we analyzed the effects of oral melatonin against NAFLD and underlying molecular mechanisms, focusing on steatosis, ER stress, mitochondrial shape and autophagy. Male C57BL/6J (WT) and SIRT1 heterozygous (HET) mice were placed either on a high-fat diet (58.4% energy from lard) (HFD) or on a standard maintenance diet (8.4% energy from lipids) for 16 weeks, drinking melatonin (10 mg/kg) or not. Indirect calorimetry, glucose tolerance, steatosis, inflammation, ER stress, mitochondrial changes, autophagy and microRNA-34a-5p expression were estimated. Melatonin improved hepatic metabolism and steatosis, influenced ER stress and mitochondrial shape, and promoted autophagy in WT HFD mice. Conversely, melatonin was ineffective in HET HFD mice, maintaining NASH changes. Indeed, autophagy was inconsistent in HET HFD or starved mice, as indicated by LC3II/LC3I ratio, p62/SQSTM1 and autophagosomes estimation. The beneficial role of melatonin in dietary induced NAFLD/NASH in mice was related to reduced expression of microRNA-34a-5p and sterol regulatory element-binding protein (SREBP1) but only in the presence of full SIRT1 availability. Full article
(This article belongs to the Special Issue Melatonin in Human Health and Diseases)
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Open AccessEditor’s ChoiceArticle
Microglial Phenotyping in Neurodegenerative Disease Brains: Identification of Reactive Microglia with an Antibody to Variant of CD105/Endoglin
Cells 2019, 8(7), 766; https://doi.org/10.3390/cells8070766 - 23 Jul 2019
Cited by 6
Abstract
Inflammation is considered a key pathological process in neurodegenerative diseases, including Alzheimer’s disease (AD) and Parkinson’s disease (PD), but there are still mechanisms not understood. In the brain, most microglia are performing essential homeostatic functions, but can also respond to pathogenic stimuli by [...] Read more.
Inflammation is considered a key pathological process in neurodegenerative diseases, including Alzheimer’s disease (AD) and Parkinson’s disease (PD), but there are still mechanisms not understood. In the brain, most microglia are performing essential homeostatic functions, but can also respond to pathogenic stimuli by producing harmful pro-inflammatory cytokines or free radicals. Distinguishing between damaging and homeostatic microglia in human diseased brain tissues is a challenge. This report describes findings using a monoclonal antibody to CD105/Endoglin (R&D Systems MAB1097) that identifies subtypes of activated microglia. CD105/Endoglin is a co-receptor for transforming growth factor beta (TGFβ) receptor that antagonizes TGFβ signaling. CD105/Endoglin is a marker for vascular endothelial cells, but was originally identified as a marker for activated macrophages. This antibody did not identify endothelial cells in brain sections, only microglia-like cells. In this study, we examined with this antibody tissue section from middle temporal gyrus derived from human brains from normal control subjects with low-plaque pathology, high-plaque pathology, and AD cases, and also substantia nigra samples from control and PD cases, in conjunction with antibodies to markers of pathology and microglia. In low-plaque pathology cases, CD105-positive microglia were mostly absent, but noticeably increased with increasing pathology. CD105-positive cells strongly colocalized with amyloid-beta plaques, but not phosphorylated tau positive tangles. In substantia nigra, strong microglial CD105 staining was observed in microglia associated with degenerating dopaminergic neurons and neuromelanin. In PD cases with few surviving dopaminergic neurons, this staining had decreased. By Western blot, this antibody identified polypeptide bands of 70 kDa in brain samples, and samples from microglia, macrophages, and brain endothelial cells. In comparison with other tested CD105 antibodies, this antibody did not recognize the glycosylated forms of CD105 on Western blots. Overall, the data indicate that this antibody and this marker could have utility for subtyping of microglia in pathologically-involved tissue. Full article
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Open AccessEditor’s ChoiceArticle
Neurological Enhancement Effects of Melatonin against Brain Injury-Induced Oxidative Stress, Neuroinflammation, and Neurodegeneration via AMPK/CREB Signaling
Cells 2019, 8(7), 760; https://doi.org/10.3390/cells8070760 - 21 Jul 2019
Cited by 20
Abstract
Oxidative stress and energy imbalance strongly correlate in neurodegenerative diseases. Repeated concussion is becoming a serious public health issue with uncontrollable adverse effects in the human population, which involve cognitive dysfunction and even permanent disability. Here, we demonstrate that traumatic brain injury (TBI) [...] Read more.
Oxidative stress and energy imbalance strongly correlate in neurodegenerative diseases. Repeated concussion is becoming a serious public health issue with uncontrollable adverse effects in the human population, which involve cognitive dysfunction and even permanent disability. Here, we demonstrate that traumatic brain injury (TBI) evokes oxidative stress, disrupts brain energy homeostasis, and boosts neuroinflammation, which further contributes to neuronal degeneration and cognitive dysfunction in the mouse brain. We also demonstrate that melatonin (an anti-oxidant agent) treatment exerts neuroprotective effects, while overcoming oxidative stress and energy depletion and reducing neuroinflammation and neurodegeneration. Male C57BL/6N mice were used as a model for repetitive mild traumatic brain injury (rmTBI) and were treated with melatonin. Protein expressions were examined via Western blot analysis, immunofluorescence, and ELISA; meanwhile, behavior analysis was performed through a Morris water maze test, and Y-maze and beam-walking tests. We found elevated oxidative stress, depressed phospho-5′AMP-activated protein kinase (p-AMPK) and phospho- CAMP-response element-binding (p-CREB) levels, and elevated p-NF-κB in rmTBI mouse brains, while melatonin treatment significantly regulated p-AMPK, p-CREB, and p-NF-κB in the rmTBI mouse brain. Furthermore, rmTBI mouse brains showed a deregulated mitochondrial system, abnormal amyloidogenic pathway activation, and cognitive functions which were significantly regulated by melatonin treatment in the mice. These findings provide evidence, for the first time, that rmTBI induces brain energy imbalance and reduces neuronal cell survival, and that melatonin treatment overcomes energy depletion and protects against brain damage via the regulation of p-AMPK/p-CREB signaling pathways in the mouse brain. Full article
(This article belongs to the Special Issue Melatonin in Human Health and Diseases)
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Open AccessEditor’s ChoiceArticle
Prognostic Significance of TWIST1, CD24, CD44, and ALDH1 Transcript Quantification in EpCAM-Positive Circulating Tumor Cells from Early Stage Breast Cancer Patients
Cells 2019, 8(7), 652; https://doi.org/10.3390/cells8070652 - 29 Jun 2019
Cited by 13
Abstract
(1) Background: The aim of the study was to evaluate the prognostic significance of EMT-associated (TWIST1) and stem-cell (SC) transcript (CD24, CD44, ALDH1) quantification in EpCAM+ circulating tumor cells (CTCs) of early breast cancer patients. (2) Methods: 100 [...] Read more.
(1) Background: The aim of the study was to evaluate the prognostic significance of EMT-associated (TWIST1) and stem-cell (SC) transcript (CD24, CD44, ALDH1) quantification in EpCAM+ circulating tumor cells (CTCs) of early breast cancer patients. (2) Methods: 100 early stage breast cancer patients and 19 healthy donors were enrolled in the study. CD24, CD44, and ALDH1 transcripts of EpCAM+ cells were quantified using a novel highly sensitive and specific quadraplex RT-qPCR, while TWIST1 transcripts were quantified by single RT-qPCR. All patients were followed up for more than 5 years. (3) Results: A significant positive correlation between overexpression of TWIST1 and CD24−/low/CD44high profile was found. Kaplan–Meier analysis revealed that the ER/PR-negative (HR-) patients and those patients with more than 3 positive lymph nodes that overexpressed TWIST1 in EpCAM+ cells had a significant lower DFI (log rank test; p < 0.001, p < 0.001) and OS (log rank test; p = 0.006, p < 0.001). Univariate and multivariate analysis also revealed the prognostic value of TWIST1 overexpression and CD24−/low/CD44high and CD24−/low/ALDH1high profile for both DFI and OS. (4) Conclusions: Detection of TWIST1 overexpression and stem-cell (CD24, CD44, ALDH1) transcripts in EpCAM+ CTCs provides prognostic information in early stage breast cancer patients. Full article
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Open AccessEditor’s ChoiceArticle
Fecal Microbiota Transplantation Controls Murine Chronic Intestinal Inflammation by Modulating Immune Cell Functions and Gut Microbiota Composition
Cells 2019, 8(6), 517; https://doi.org/10.3390/cells8060517 - 28 May 2019
Cited by 17
Abstract
Different gastrointestinal disorders, including inflammatory bowel diseases (IBD), have been linked to alterations of the gut microbiota composition, namely dysbiosis. Fecal microbiota transplantation (FMT) is considered an encouraging therapeutic approach for ulcerative colitis patients, mostly as a consequence of normobiosis restoration. We recently [...] Read more.
Different gastrointestinal disorders, including inflammatory bowel diseases (IBD), have been linked to alterations of the gut microbiota composition, namely dysbiosis. Fecal microbiota transplantation (FMT) is considered an encouraging therapeutic approach for ulcerative colitis patients, mostly as a consequence of normobiosis restoration. We recently showed that therapeutic effects of FMT during acute experimental colitis are linked to functional modulation of the mucosal immune system and of the gut microbiota composition. Here we analysed the effects of therapeutic FMT administration during chronic experimental colitis, a condition more similar to that of IBD patients, on immune-mediated mucosal inflammatory pathways. Mucus and feces from normobiotic donors were orally administered to mice with established chronic Dextran Sodium Sulphate (DSS)-induced colitis. Immunophenotypes and functions of infiltrating colonic immune cells were evaluated by cytofluorimetric analysis. Compositional differences in the intestinal microbiome were analyzed by 16S rRNA sequencing. Therapeutic FMT in mice undergoing chronic intestinal inflammation was capable to decrease colonic inflammation by modulating the expression of pro-inflammatory genes, antimicrobial peptides, and mucins. Innate and adaptive mucosal immune cells manifested a reduced pro-inflammatory profile in FMT-treated mice. Finally, restoration of a normobiotic core ecology contributed to the resolution of inflammation. Thus, FMT is capable of controlling chronic intestinal experimental colitis by inducing a concerted activation of anti-inflammatory immune pathways, mechanistically supporting the positive results of FMT treatment reported in ulcerative colitis patients. Full article
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Open AccessFeature PaperEditor’s ChoiceArticle
Single Cell RNA Sequencing Identifies Subsets of Hepatic Stellate Cells and Myofibroblasts in Liver Fibrosis
Cells 2019, 8(5), 503; https://doi.org/10.3390/cells8050503 - 24 May 2019
Cited by 37
Abstract
Activation of hepatic stellate cells (HSCs) and their trans-differentiation towards collagen-secreting myofibroblasts (MFB) promote liver fibrosis progression. During chronic liver disease, resting HSCs become activated by inflammatory and injury signals. However, HSCs/MFB not only produce collagen, but also secrete cytokines, participate in metabolism, [...] Read more.
Activation of hepatic stellate cells (HSCs) and their trans-differentiation towards collagen-secreting myofibroblasts (MFB) promote liver fibrosis progression. During chronic liver disease, resting HSCs become activated by inflammatory and injury signals. However, HSCs/MFB not only produce collagen, but also secrete cytokines, participate in metabolism, and have biomechanical properties. We herein aimed to characterize the heterogeneity of these liver mesenchymal cells by single cell RNA sequencing. In vivo resting HSCs or activated MFB were isolated from C57BL6/J mice challenged by carbon tetrachloride (CCl4) intraperitoneally for 3 weeks to induce liver fibrosis and compared to in vitro cultivated MFB. While resting HSCs formed a homogenous population characterized by high platelet derived growth factor receptor β (PDGFRβ) expression, in vivo and in vitro activated MFB split into heterogeneous populations, characterized by α-smooth muscle actin (α-SMA), collagens, or immunological markers. S100 calcium binding protein A6 (S100A6) was a universal marker of activated MFB on both the gene and protein expression level. Compared to the heterogeneity of in vivo MFB, MFB in vitro sequentially and only transiently expressed marker genes, such as chemokines, during culture activation. Taken together, our data demonstrate the heterogeneity of HSCs and MFB, indicating the existence of functionally relevant subsets in hepatic fibrosis. Full article
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Open AccessEditor’s ChoiceArticle
Anti-Inflammatory Effects by Pharmacological Inhibition or Knockdown of Fatty Acid Amide Hydrolase in BV2 Microglial Cells
Cells 2019, 8(5), 491; https://doi.org/10.3390/cells8050491 - 22 May 2019
Cited by 5
Abstract
Fatty acid amide hydrolase (FAAH) has been recognized as a therapeutic target for several neurological diseases because its inhibition can exert neuroprotective and anti-inflammatory effects by boosting the endogenous levels of N-acylethanolamines. However, previous studies have shown inconsistent results by pharmacological inhibition [...] Read more.
Fatty acid amide hydrolase (FAAH) has been recognized as a therapeutic target for several neurological diseases because its inhibition can exert neuroprotective and anti-inflammatory effects by boosting the endogenous levels of N-acylethanolamines. However, previous studies have shown inconsistent results by pharmacological inhibition and genetic deletion of FAAH in response to inflammation. In this study we used two inhibitors, PF3845 and URB597, together with siRNA knockdown to characterize further the effects of FAAH inhibition in BV2 microglial cells. Treatment with PF3845 suppressed lipopolysaccharide (LPS)-induced prostaglandin E2 (PGE2) production, and down-regulated cyclooxygenase-2 and microsomal PGE synthase. PF3845 reduced the expression of pro-inflammatory cytokines but had no effect on the expression of anti-inflammatory cytokines. The anti-inflammatory effects of URB597 were not as potent as those of PF3845. Knockdown of FAAH also suppressed PGE2 production and pro-inflammatory gene expression. Interestingly, FAAH knockdown enhanced expression of anti-inflammatory molecules in both the absence and presence of LPS treatment. The anti-inflammatory effects of FAAH inhibition and knockdown were not affected by the cannabinoid receptor antagonists or the peroxisome proliferator-activated receptor (PPAR) antagonists. Although inhibition and knockdown of FAAH have potent anti-inflammatory effects and possibly lead to the dynamic change of microglial gene regulation, the underlying mechanisms remain to be elucidated. Full article
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Open AccessFeature PaperEditor’s ChoiceArticle
An In Vitro System for Evaluating Molecular Targeted Drugs Using Lung Patient-Derived Tumor Organoids
Cells 2019, 8(5), 481; https://doi.org/10.3390/cells8050481 - 20 May 2019
Cited by 8
Abstract
Patient-derived tumor organoids (PDOs) represent a promising preclinical cancer model that better replicates disease, compared with traditional cell culture models. We have established PDOs from various human tumors to accurately and efficiently recapitulate the tissue architecture and function. Molecular targeted therapies with remarkable [...] Read more.
Patient-derived tumor organoids (PDOs) represent a promising preclinical cancer model that better replicates disease, compared with traditional cell culture models. We have established PDOs from various human tumors to accurately and efficiently recapitulate the tissue architecture and function. Molecular targeted therapies with remarkable efficacy are currently in use against various tumors. Thus, there is a need for in vitro functional-potency assays that can be used to test the efficacy of molecular targeted drugs and model complex interactions between immune cells and tumor cells to evaluate the potential for cancer immunotherapy. This study represents an in vitro evaluation of different classes of molecular targeted drugs, including small-molecule inhibitors, monoclonal antibodies, and an antibody-drug conjugate, using lung PDOs. We evaluated epidermal growth factor receptor and human epidermal growth factor receptor 2 (HER2) inhibitors using a suitable high-throughput assay system. Next, the antibody-dependent cellular cytotoxicity (ADCC) activity of an anti-HER2 monoclonal antibody was evaluated to visualize the interactions of immune cells with PDOs during ADCC responses. Moreover, an evaluation system was developed for the immune checkpoint inhibitors, nivolumab and pembrolizumab, using PDOs. Our results demonstrate that the in vitro assay systems using PDOs were suitable for evaluating molecular targeted drugs under conditions that better reflect pathological conditions. Full article
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Open AccessEditor’s ChoiceArticle
A Cleared View on Retinal Organoids
Cells 2019, 8(5), 391; https://doi.org/10.3390/cells8050391 - 28 Apr 2019
Cited by 13
Abstract
Human induced pluripotent stem cell (hiPSC)-derived organoids mimicking tissues and organs in vitro have advanced medical research, as they opened up new possibilities for in-depth basic research on human organ development as well as providing a human in vitro model for personalized therapeutic [...] Read more.
Human induced pluripotent stem cell (hiPSC)-derived organoids mimicking tissues and organs in vitro have advanced medical research, as they opened up new possibilities for in-depth basic research on human organ development as well as providing a human in vitro model for personalized therapeutic approaches. hiPSC-derived retinal organoids have proven to be of great value for modeling the human retina featuring a very similar cellular composition, layering, and functionality. The technically challenging imaging of three-dimensional structures such as retinal organoids has, however, raised the need for robust whole-organoid imaging techniques. To improve imaging of retinal organoids we optimized a passive clearing technique (PACT), which enables high-resolution visualization of fragile intra-tissue structures. Using cleared retinal organoids, we could greatly enhance the antibody labeling efficiency and depth of imaging at high resolution, thereby improving the three-dimensional microscopy output. In that course, we were able to identify the spatial morphological shape and organization of, e.g., photoreceptor cells and bipolar cell layers. Moreover, we used the synaptic protein CtBP2/Ribeye to visualize the interconnection points of photoreceptor and bipolar cells forming the retinal-specific ribbon synapses. Full article
(This article belongs to the Special Issue Stem Cells in Personalized Medicine)
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Open AccessEditor’s ChoiceArticle
Rainbow Trout Red Blood Cells Exposed to Viral Hemorrhagic Septicemia Virus Up-Regulate Antigen-Processing Mechanisms and MHC I&II, CD86, and CD83 Antigen-presenting Cell Markers
Cells 2019, 8(5), 386; https://doi.org/10.3390/cells8050386 - 27 Apr 2019
Cited by 5
Abstract
Nucleated teleost red blood cells (RBCs) are known to express molecules from the major histocompatibility complex and peptide-generating processes such as autophagy and proteasomes, but the role of RBCs in antigen presentation of viruses have not been studied yet. In this study, RBCs [...] Read more.
Nucleated teleost red blood cells (RBCs) are known to express molecules from the major histocompatibility complex and peptide-generating processes such as autophagy and proteasomes, but the role of RBCs in antigen presentation of viruses have not been studied yet. In this study, RBCs exposed ex vivo to viral hemorrhagic septicemia virus (VHSV) were evaluated by means of transcriptomic and proteomic approaches. Genes and proteins related to antigen presentation molecules, proteasome degradation, and autophagy were up-regulated. VHSV induced accumulation of ubiquitinated proteins in ex vivo VHSV-exposed RBCs and showed at the same time a decrease of proteasome activity. Furthermore, induction of autophagy was detected by evaluating LC3 protein levels. Sequestosome-1/p62 underwent degradation early after VHSV exposure, and it may be a link between ubiquitination and autophagy activation. Inhibition of autophagosome degradation with niclosamide resulted in intracellular detection of N protein of VHSV (NVHSV) and p62 accumulation. In addition, antigen presentation cell markers, such as major histocompatibility complex (MHC) class I & II, CD83, and CD86, increased at the transcriptional and translational level in rainbow trout RBCs exposed to VHSV. In summary, we show that nucleated rainbow trout RBCs can degrade VHSV while displaying an antigen-presenting cell (APC)-like profile. Full article
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Open AccessEditor’s ChoiceArticle
MAGI1 Mediates eNOS Activation and NO Production in Endothelial Cells in Response to Fluid Shear Stress
Cells 2019, 8(5), 388; https://doi.org/10.3390/cells8050388 - 27 Apr 2019
Cited by 9
Abstract
Fluid shear stress stimulates endothelial nitric oxide synthase (eNOS) activation and nitric oxide (NO) production through multiple kinases, including protein kinase A (PKA), AMP-activated protein kinase (AMPK), AKT and Ca2+/calmodulin-dependent protein kinase II (CaMKII). Membrane-associated guanylate kinase (MAGUK) with inverted domain [...] Read more.
Fluid shear stress stimulates endothelial nitric oxide synthase (eNOS) activation and nitric oxide (NO) production through multiple kinases, including protein kinase A (PKA), AMP-activated protein kinase (AMPK), AKT and Ca2+/calmodulin-dependent protein kinase II (CaMKII). Membrane-associated guanylate kinase (MAGUK) with inverted domain structure-1 (MAGI1) is an adaptor protein that stabilizes epithelial and endothelial cell-cell contacts. The aim of this study was to assess the unknown role of endothelial cell MAGI1 in response to fluid shear stress. We show constitutive expression and co-localization of MAGI1 with vascular endothelial cadherin (VE-cadherin) in endothelial cells at cellular junctions under static and laminar flow conditions. Fluid shear stress increases MAGI1 expression. MAGI1 silencing perturbed flow-dependent responses, specifically, Krüppel-like factor 4 (KLF4) expression, endothelial cell alignment, eNOS phosphorylation and NO production. MAGI1 overexpression had opposite effects and induced phosphorylation of PKA, AMPK, and CAMKII. Pharmacological inhibition of PKA and AMPK prevented MAGI1-mediated eNOS phosphorylation. Consistently, MAGI1 silencing and PKA inhibition suppressed the flow-induced NO production. Endothelial cell-specific transgenic expression of MAGI1 induced PKA and eNOS phosphorylation in vivo and increased NO production ex vivo in isolated endothelial cells. In conclusion, we have identified endothelial cell MAGI1 as a previously unrecognized mediator of fluid shear stress-induced and PKA/AMPK dependent eNOS activation and NO production. Full article
(This article belongs to the Special Issue The Molecular and Cellular Basis of Cardiovascular Disease)
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Open AccessEditor’s ChoiceArticle
Combined Inhibition of TGF-β Signaling and the PD-L1 Immune Checkpoint Is Differentially Effective in Tumor Models
Cells 2019, 8(4), 320; https://doi.org/10.3390/cells8040320 - 05 Apr 2019
Cited by 26
Abstract
Antibodies blocking the programmed death-ligand 1 (PD-L1) have shown impressive and durable responses in clinical studies. However, this type of immunotherapy is only effective in a subset of patients and not sufficient for rejection of all tumor types. In this study, we explored [...] Read more.
Antibodies blocking the programmed death-ligand 1 (PD-L1) have shown impressive and durable responses in clinical studies. However, this type of immunotherapy is only effective in a subset of patients and not sufficient for rejection of all tumor types. In this study, we explored in two mouse tumor models whether the antitumor effect could be enhanced by the combined blockade of PD-L1 and transforming growth factor-β (TGF-β), a potent immunosuppressive cytokine. The effect of anti-PD-L1 mouse monoclonal (mAb) and a TGF-β type I receptor small molecule kinase inhibitor (LY364947) was evaluated in the highly immunogenic mouse MC38 colon adenocarcinoma and the poorly immunogenic mouse KPC1 pancreatic tumor model. In the MC38 tumor model, LY364947 monotherapy did not show any antitumor effect, whereas treatment with anti-PD-L1 mAb significantly delayed tumor outgrowth. However, combination therapy showed the strongest therapeutic efficacy, resulting in improved long-term survival compared with anti-PD-L1 mAb monotherapy. This improved survival was associated with an increased influx of CD8+ T cells in the tumor microenvironment. In the KPC1 tumor model, LY364947 did not enhance the antitumor effect of anti-PD-L1 mAb. Despite this, delayed KPC1 tumor outgrowth was observed in the LY364947-treated group and this treatment led to a significant reduction of CD4+ T cells in the tumor microenvironment. Together, our data indicate that an additive anti-tumor response of dual targeting PD-L1 and TGF-β is dependent on the tumor model used, highlighting the importance of selecting appropriate cancer types, using in-depth analysis of the tumor microenvironment, which can benefit from combinatorial immunotherapy regimens. Full article
(This article belongs to the Special Issue TGF-beta/BMP Signaling Pathway)
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Open AccessEditor’s ChoiceArticle
Hepatitis C Virus Non-Structural Protein 5A (NS5A) Disrupts Mitochondrial Dynamics and Induces Mitophagy
Cells 2019, 8(4), 290; https://doi.org/10.3390/cells8040290 - 29 Mar 2019
Cited by 17
Abstract
Mitophagy is a selective form of autophagy, targeting damaged mitochondria for lysosomal degradation. Although HCV infection has been shown to induce mitophagy, the precise underlying mechanism and the effector protein responsible remain unclear. Herein, we demonstrated that the HCV non-structural protein 5A (NS5A) [...] Read more.
Mitophagy is a selective form of autophagy, targeting damaged mitochondria for lysosomal degradation. Although HCV infection has been shown to induce mitophagy, the precise underlying mechanism and the effector protein responsible remain unclear. Herein, we demonstrated that the HCV non-structural protein 5A (NS5A) plays a key role in regulating cellular mitophagy. Specifically, the expression of HCV NS5A in the hepatoma cells triggered hallmarks of mitophagy including mitochondrial fragmentation, loss of mitochondrial membrane potential, and Parkin translocation to the mitochondria. Furthermore, mitophagy induction through the expression of NS5A led to an increase in autophagic flux as demonstrated by an accumulation of LC3II in the presence of bafilomycin and a time-dependent decrease in p62 protein level. Intriguingly, the expression of NS5A concomitantly enhanced reactive oxygen species (ROS) production, and treatment with an antioxidant attenuated the NS5A-induced mitophagy event. These phenomena are similarly recapitulated in the NS5A-expressing HCV subgenomic replicon cells. Finally, we demonstrated that expression of HCV core, which has been documented to inhibit mitophagy, blocked the mitophagy induction both in cells harboring HCV replicating subgenomes or expressing NS5A alone. Our results, therefore, identified a new role for NS5A as an important regulator of HCV-induced mitophagy and have implications to broadening our understanding of the HCV-mitophagy interplay. Full article
(This article belongs to the Special Issue Hepatitis C Virus and Host Interactions)
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Open AccessEditor’s ChoiceArticle
Novel Flavivirus Antiviral That Targets the Host Nuclear Transport Importin α/β1 Heterodimer
Cells 2019, 8(3), 281; https://doi.org/10.3390/cells8030281 - 24 Mar 2019
Cited by 15
Abstract
Dengue virus (DENV) threatens almost 70% of the world’s population, with no effective vaccine or therapeutic currently available. A key contributor to infection is nuclear localisation in the infected cell of DENV nonstructural protein 5 (NS5) through the action of the host importin [...] Read more.
Dengue virus (DENV) threatens almost 70% of the world’s population, with no effective vaccine or therapeutic currently available. A key contributor to infection is nuclear localisation in the infected cell of DENV nonstructural protein 5 (NS5) through the action of the host importin (IMP) α/β1 proteins. Here, we used a range of microscopic, virological and biochemical/biophysical approaches to show for the first time that the small molecule GW5074 has anti-DENV action through its novel ability to inhibit NS5–IMPα/β1 interaction in vitro as well as NS5 nuclear localisation in infected cells. Strikingly, GW5074 not only inhibits IMPα binding to IMPβ1, but can dissociate preformed IMPα/β1 heterodimer, through targeting the IMPα armadillo (ARM) repeat domain to impact IMPα thermal stability and α-helicity, as shown using analytical ultracentrifugation, thermostability analysis and circular dichroism measurements. Importantly, GW5074 has strong antiviral activity at low µM concentrations against not only DENV-2, but also zika virus and West Nile virus. This work highlights DENV NS5 nuclear targeting as a viable target for anti-flaviviral therapeutics. Full article
(This article belongs to the Special Issue Nuclear Transport in Ageing and Diseases)
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Open AccessEditor’s ChoiceArticle
Promethin Is a Conserved Seipin Partner Protein
Cells 2019, 8(3), 268; https://doi.org/10.3390/cells8030268 - 21 Mar 2019
Cited by 21
Abstract
Seipin (BSCL2/SPG17) is a key factor in lipid droplet (LD) biology, and its dysfunction results in severe pathologies, including the fat storage disease Berardinelli-Seip congenital lipodystrophy type 2, as well as several neurological seipinopathies. Despite its importance for human health, the molecular role [...] Read more.
Seipin (BSCL2/SPG17) is a key factor in lipid droplet (LD) biology, and its dysfunction results in severe pathologies, including the fat storage disease Berardinelli-Seip congenital lipodystrophy type 2, as well as several neurological seipinopathies. Despite its importance for human health, the molecular role of seipin is still enigmatic. Seipin is evolutionarily conserved from yeast to humans. In yeast, seipin was recently found to cooperate with the lipid droplet organization (LDO) proteins, Ldo16 and Ldo45, two structurally-related proteins involved in LD function and identity that display remote homology to the human protein promethin/TMEM159. In this study, we show that promethin is indeed an LD-associated protein that forms a complex with seipin, and its localization to the LD surface can be modulated by seipin expression levels. We thus identify promethin as a novel seipin partner protein. Full article
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Open AccessEditor’s ChoiceArticle
Sigma-1 Receptor Activation Induces Autophagy and Increases Proteostasis Capacity In Vitro and In Vivo
Cells 2019, 8(3), 211; https://doi.org/10.3390/cells8030211 - 02 Mar 2019
Cited by 15
Abstract
Dysfunction of autophagy and disturbed protein homeostasis are linked to the pathogenesis of human neurodegenerative diseases and the modulation of autophagy as the protein clearance process has become one key pharmacological target. Due to the role of sigma-1 receptors (Sig-1R) in learning and [...] Read more.
Dysfunction of autophagy and disturbed protein homeostasis are linked to the pathogenesis of human neurodegenerative diseases and the modulation of autophagy as the protein clearance process has become one key pharmacological target. Due to the role of sigma-1 receptors (Sig-1R) in learning and memory, and the described pleiotropic neuroprotective effects in various experimental paradigms, Sig-1R activation is recognized as one potential approach for prevention and therapy of neurodegeneration and, interestingly, in amyotrophic lateral sclerosis associated with mutated Sig-1R, autophagy is disturbed. Here we analyzed the effects of tetrahydro-N,N-dimethyl-2,2-diphenyl-3-furanmethanamine hydrochloride (ANAVEX2-73), a muscarinic receptor ligand and Sig-1R agonist, on autophagy and proteostasis. We describe, at the molecular level, for the first time, that pharmacological Sig-1R activation a) enhances the autophagic flux in human cells and in Caenorhabditis elegans and b) increases proteostasis capacity, ultimately ameliorating paralysis caused by protein aggregation in C. elegans. ANAVEX2-73 is already in clinical investigation for the treatment of Alzheimer’s disease, and the novel activities of this compound on autophagy and proteostasis described here may have consequences for the use and further development of the Sig-1R as a drug target in the future. Moreover, our study defines the Sig-1R as an upstream modulator of canonical autophagy, which may have further implications for various conditions with dysfunctional autophagy, besides neurodegeneration. Full article
(This article belongs to the Special Issue Proteostasis and Autophagy)
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Open AccessEditor’s ChoiceArticle
Anti-Inflammatory Effect of Sulforaphane on LPS-Activated Microglia Potentially through JNK/AP-1/NF-κB Inhibition and Nrf2/HO-1 Activation
Cells 2019, 8(2), 194; https://doi.org/10.3390/cells8020194 - 22 Feb 2019
Cited by 46
Abstract
Sulforaphane (SFN), a potent nuclear factor erythroid 2-related factor 2 (Nrf2) activator, is present in the species of the Brassicaceae, especially in broccoli sprouts. In this study, the effects of SFN against microglial activation and inflammation, and the potential mechanisms involved, were analyzed. [...] Read more.
Sulforaphane (SFN), a potent nuclear factor erythroid 2-related factor 2 (Nrf2) activator, is present in the species of the Brassicaceae, especially in broccoli sprouts. In this study, the effects of SFN against microglial activation and inflammation, and the potential mechanisms involved, were analyzed. As mitogen-activated protein kinase (MAPK) signaling plays a key role in microglial activation and inflammation, we focused on the role of SFN in regulating the MAPK signaling regulation of the inflammatory and anti-inflammatory cascades in lipopolysaccharide (LPS)-activated microglia. The anti-inflammatory and immunomodulatory effects of SFN were explored by evaluating the expression and secretion of inflammatory proteins, cytokines, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and activator protein-1 (AP-1) under pre- and post-treatment conditions. Under the SFN pre- and post-treatment conditions, the MAPK phosphorylation levels were significantly reduced in both acutely and chronically activated microglial cells. SFN also reduced the c-Jun N-terminal kinase (JNK) phosphorylation levels, which subsequently reduced NF-κB and AP-1 signaling. As a result, the expression of the inflammatory mediators (iNOS, COX-2, NO, and PGE2) and proinflammatory cytokines (TNF-α, IL-6, and IL-1β) was decreased. At the same time, SFN increased the expression of Nrf2 and heme oxygenase-1 (HO-1) as well as the production of the anti-inflammatory cytokines IL-10 and IL-4. In conclusion, this study demonstrated that SFN exerts an anti-neuroinflammatory effect on microglia through JNK/AP-1/NF-κB pathway inhibition and Nrf2/HO-1 pathway activation. Full article
(This article belongs to the Section Cell Signaling and Regulated Cell Death)
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Open AccessEditor’s ChoiceArticle
Apolipoprotein E4 Alters Astrocyte Fatty Acid Metabolism and Lipid Droplet Formation
Cells 2019, 8(2), 182; https://doi.org/10.3390/cells8020182 - 20 Feb 2019
Cited by 27
Abstract
Lipid droplets (LDs) serve as energy rich reservoirs and have been associated with apolipoprotein E (APOE) and neurodegeneration. The E4 allele of APOE (E4) is the strongest genetic risk factor for the development of late onset Alzheimer’s disease (AD). Since both [...] Read more.
Lipid droplets (LDs) serve as energy rich reservoirs and have been associated with apolipoprotein E (APOE) and neurodegeneration. The E4 allele of APOE (E4) is the strongest genetic risk factor for the development of late onset Alzheimer’s disease (AD). Since both E4 carriers and individuals with AD exhibit a state of cerebral lipid dyshomeostasis, we hypothesized that APOE may play a role in regulating LD metabolism. We found that astrocytes expressing E4 accumulate significantly more and smaller LDs compared to E3 astrocytes. Accordingly, expression of perilipin-2, an essential LD protein component, was higher in E4 astrocytes. We then probed fatty acid (FA) metabolism and found E4 astrocytes to exhibit decreased uptake of palmitate, and decreased oxidation of exogenously supplied oleate and palmitate. We then measured oxygen consumption rate, and found E4 astrocytes to consume more oxygen for endogenous FA oxidation and accumulate more LD-derived metabolites due to incomplete oxidation. Lastly, we found that E4 astrocytes are more sensitive to carnitine palmitoyltransferase-1 inhibition than E3 astrocytes. These findings offer the potential for further studies investigating the link between astrocyte lipid storage, utilization, and neurodegenerative disease as a function of APOE genotype. Full article
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Open AccessEditor’s ChoiceArticle
Carnosine Prevents Aβ-Induced Oxidative Stress and Inflammation in Microglial Cells: A Key Role of TGF-β1
Cells 2019, 8(1), 64; https://doi.org/10.3390/cells8010064 - 17 Jan 2019
Cited by 24
Abstract
Carnosine (β-alanyl-L-histidine), a dipeptide, is an endogenous antioxidant widely distributed in excitable tissues like muscles and the brain. Carnosine is involved in cellular defense mechanisms against oxidative stress, including the inhibition of amyloid-beta (Aβ) aggregation and the scavenging of reactive species. Microglia play [...] Read more.
Carnosine (β-alanyl-L-histidine), a dipeptide, is an endogenous antioxidant widely distributed in excitable tissues like muscles and the brain. Carnosine is involved in cellular defense mechanisms against oxidative stress, including the inhibition of amyloid-beta (Aβ) aggregation and the scavenging of reactive species. Microglia play a central role in the pathogenesis of Alzheimer’s disease, promoting neuroinflammation through the secretion of inflammatory mediators and free radicals. However, the effects of carnosine on microglial cells and neuroinflammation are not well understood. In the present work, carnosine was tested for its ability to protect BV-2 microglial cells against oligomeric Aβ1-42-induced oxidative stress and inflammation. Carnosine prevented cell death in BV-2 cells challenged with Aβ oligomers through multiple mechanisms. Specifically, carnosine lowered the oxidative stress by decreasing NO and O2−• intracellular levels as well as the expression of iNOS and Nox enzymes. Carnosine also decreased the secretion of pro-inflammatory cytokines such as IL-1β, simultaneously rescuing IL-10 levels and increasing the expression and the release of TGF-β1. Carnosine also prevented Aβ-induced neurodegeneration in mixed neuronal cultures challenged with Aβ oligomers, and these neuroprotective effects were completely abolished by SB431542, a selective inhibitor of the type-1 TGF-β receptor. Our data suggest a multimodal mechanism of action of carnosine underlying its protective effects on microglial cells against Aβ toxicity with a key role of TGF-β1 in mediating these protective effects. Full article
(This article belongs to the Special Issue TGF-beta/BMP Signaling Pathway)
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Open AccessEditor’s ChoiceArticle
Oxidative Stress Induces Telomere Dysfunction and Senescence by Replication Fork Arrest
Cells 2019, 8(1), 19; https://doi.org/10.3390/cells8010019 - 03 Jan 2019
Cited by 22
Abstract
Oxidative DNA damage, particularly 8-oxoguanine, represents the most frequent DNA damage in human cells, especially at the telomeric level. The presence of oxidative lesions in the DNA can hinder the replication fork and is able to activate the DNA damage response. In this [...] Read more.
Oxidative DNA damage, particularly 8-oxoguanine, represents the most frequent DNA damage in human cells, especially at the telomeric level. The presence of oxidative lesions in the DNA can hinder the replication fork and is able to activate the DNA damage response. In this study, we wanted to understand the mechanisms by which oxidative damage causes telomere dysfunction and senescence in human primary fibroblasts. After acute oxidative stress at telomeres, our data demonstrated a reduction in TRF1 and TRF2, which are involved in proper telomere replication and T-loop formation, respectively. Furthermore, we observed a higher level of γH2AX with respect to 53BP1 at telomeres, suggesting a telomeric replication fork stall rather than double-strand breaks. To confirm this finding, we studied the replication of telomeres by Chromosome Orientation-FISH (CO-FISH). The data obtained show an increase in unreplicated telomeres after hydrogen peroxide treatment, corroborating the idea that the presence of 8-oxoG can induce replication fork arrest at telomeres. Lastly, we analyzed the H3K9me3 histone mark after oxidative stress at telomeres, and our results showed an increase of this marker, most likely inducing the heterochromatinization of telomeres. These results suggest that 8-oxoG is fundamental in oxidative stress-induced telomeric damage, principally causing replication fork arrest. Full article
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Open AccessEditor’s ChoiceArticle
A Rise in ATP, ROS, and Mitochondrial Content upon Glucose Withdrawal Correlates with a Dysregulated Mitochondria Turnover Mediated by the Activation of the Protein Deacetylase SIRT1
Cells 2019, 8(1), 11; https://doi.org/10.3390/cells8010011 - 27 Dec 2018
Cited by 12
Abstract
Glucose withdrawal has been used as a model for the study of homeostatic defense mechanisms, especially for how cells cope with a shortage of nutrient supply by enhancing catabolism. However, detailed cellular responses to glucose withdrawal have been poorly studied, and are controversial. [...] Read more.
Glucose withdrawal has been used as a model for the study of homeostatic defense mechanisms, especially for how cells cope with a shortage of nutrient supply by enhancing catabolism. However, detailed cellular responses to glucose withdrawal have been poorly studied, and are controversial. In this study, we determined how glucose withdrawal affects mitochondrial activity, and the quantity and the role of SIRT1 in these changes. The results of our study indicate a substantial increase in ATP production from mitochondria, through an elevation of mitochondrial biogenesis, mediated by SIRT1 activation that is driven by increased NAD+/NADH ratio. Moreover, mitochondria persisted in the cells as elongated forms, and apparently evaded mitophagic removal. This led to a steady increase in mitochondria content and the reactive oxygen species (ROS) generated from them, indicating failure in ATP and ROS homeostasis, due to a misbalance in SIRT1-mediated mitochondria turnover in conditions of glucose withdrawal. Our results suggest that SIRT1 activation alone cannot properly manage energy homeostasis under certain metabolic crisis conditions. Full article
(This article belongs to the Special Issue Mitochondrial Biology in Health and Disease)
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Review

Jump to: Research

Open AccessEditor’s ChoiceReview
FOXO3a from the Nucleus to the Mitochondria: A Round Trip in Cellular Stress Response
Cells 2019, 8(9), 1110; https://doi.org/10.3390/cells8091110 - 19 Sep 2019
Cited by 21
Abstract
Cellular stress response is a universal mechanism that ensures the survival or negative selection of cells in challenging conditions. The transcription factor Forkhead box protein O3 (FOXO3a) is a core regulator of cellular homeostasis, stress response, and longevity since it can modulate a [...] Read more.
Cellular stress response is a universal mechanism that ensures the survival or negative selection of cells in challenging conditions. The transcription factor Forkhead box protein O3 (FOXO3a) is a core regulator of cellular homeostasis, stress response, and longevity since it can modulate a variety of stress responses upon nutrient shortage, oxidative stress, hypoxia, heat shock, and DNA damage. FOXO3a activity is regulated by post-translational modifications that drive its shuttling between different cellular compartments, thereby determining its inactivation (cytoplasm) or activation (nucleus and mitochondria). Depending on the stress stimulus and subcellular context, activated FOXO3a can induce specific sets of nuclear genes, including cell cycle inhibitors, pro-apoptotic genes, reactive oxygen species (ROS) scavengers, autophagy effectors, gluconeogenic enzymes, and others. On the other hand, upon glucose restriction, 5′-AMP-activated protein kinase (AMPK) and mitogen activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) -dependent FOXO3a mitochondrial translocation allows the transcription of oxidative phosphorylation (OXPHOS) genes, restoring cellular ATP levels, while in cancer cells, mitochondrial FOXO3a mediates survival upon genotoxic stress induced by chemotherapy. Interestingly, these target genes and their related pathways are diverse and sometimes antagonistic, suggesting that FOXO3a is an adaptable player in the dynamic homeostasis of normal and stressed cells. In this review, we describe the multiple roles of FOXO3a in cellular stress response, with a focus on both its nuclear and mitochondrial functions. Full article
(This article belongs to the Special Issue Molecular and Cellular Mechanisms of Stress Responses)
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Open AccessEditor’s ChoiceReview
Trends and Challenges in Tumor Anti-Angiogenic Therapies
Cells 2019, 8(9), 1102; https://doi.org/10.3390/cells8091102 - 18 Sep 2019
Cited by 37
Abstract
Excessive abnormal angiogenesis plays a pivotal role in tumor progression and is a hallmark of solid tumors. This process is driven by an imbalance between pro- and anti-angiogenic factors dominated by the tissue hypoxia-triggered overproduction of vascular endothelial growth factor (VEGF). VEGF-mediated signaling [...] Read more.
Excessive abnormal angiogenesis plays a pivotal role in tumor progression and is a hallmark of solid tumors. This process is driven by an imbalance between pro- and anti-angiogenic factors dominated by the tissue hypoxia-triggered overproduction of vascular endothelial growth factor (VEGF). VEGF-mediated signaling has quickly become one of the most promising anti-angiogenic therapeutic targets in oncology. Nevertheless, the clinical efficacy of this approach is severely limited in certain tumor types or shows only transient efficacy in patients. Acquired or intrinsic therapy resistance associated with anti-VEGF monotherapeutic approaches indicates the necessity of a paradigm change when targeting neoangiogenesis in solid tumors. In this context, the elaboration of the conceptual framework of “vessel normalization” might be a promising approach to increase the efficacy of anti-angiogenic therapies and the survival rates of patients. Indeed, the promotion of vessel maturation instead of regressing tumors by vaso-obliteration could result in reduced tumor hypoxia and improved drug delivery. The implementation of such anti-angiogenic strategies, however, faces several pitfalls due to the potential involvement of multiple pro-angiogenic factors and modulatory effects of the innate and adaptive immune system. Thus, effective treatments bypassing relapses associated with anti-VEGF monotherapies or breaking the intrinsic therapy resistance of solid tumors might use combination therapies or agents with a multimodal mode of action. This review enumerates some of the current approaches and possible future directions of treating solid tumors by targeting neovascularization. Full article
(This article belongs to the Special Issue Angiogenesis in Cancer)
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Open AccessEditor’s ChoiceReview
Membrane-Bound Meet Membraneless in Health and Disease
Cells 2019, 8(9), 1000; https://doi.org/10.3390/cells8091000 - 29 Aug 2019
Cited by 4
Abstract
Membraneless organelles (MLOs) are defined as cellular structures that are not sealed by a lipidic membrane and are shown to form by phase separation. They exist in both the nucleus and the cytoplasm that is also heavily populated by numerous membrane-bound organelles. Even [...] Read more.
Membraneless organelles (MLOs) are defined as cellular structures that are not sealed by a lipidic membrane and are shown to form by phase separation. They exist in both the nucleus and the cytoplasm that is also heavily populated by numerous membrane-bound organelles. Even though the name membraneless suggests that MLOs are free of membrane, both membrane and factors regulating membrane trafficking steps are emerging as important components of MLO formation and function. As a result, we name them biocondensates. In this review, we examine the relationships between biocondensates and membrane. First, inhibition of membrane trafficking in the early secretory pathway leads to the formation of biocondensates (P-bodies and Sec bodies). In the same vein, stress granules have a complex relationship with the cyto-nuclear transport machinery. Second, membrane contributes to the regulated formation of phase separation in the cells and we will present examples including clustering at the plasma membrane and at the synapse. Finally, the whole cell appears to transit from an interphase phase-separated state to a mitotic diffuse state in a DYRK3 dependent manner. This firmly establishes a crosstalk between the two types of cell organization that will need to be further explored. Full article
(This article belongs to the Special Issue Membrane Traffic in Health and Disease)
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Open AccessEditor’s ChoiceReview
Physiology, Pathology and Regeneration of Salivary Glands
Cells 2019, 8(9), 976; https://doi.org/10.3390/cells8090976 - 26 Aug 2019
Cited by 13
Abstract
Salivary glands are essential structures in the oral cavity. A variety of diseases, such as cancer, autoimmune diseases, infections and physical traumas, can alter the functionality of these glands, greatly impacting the quality of life of patients. To date, no definitive therapeutic approach [...] Read more.
Salivary glands are essential structures in the oral cavity. A variety of diseases, such as cancer, autoimmune diseases, infections and physical traumas, can alter the functionality of these glands, greatly impacting the quality of life of patients. To date, no definitive therapeutic approach can compensate the impairment of salivary glands, and treatment are purely symptomatic. Understanding the cellular and molecular control of salivary glands function is, therefore, highly relevant for therapeutic purposes. In this review, we provide a starting platform for future studies in basic biology and clinical research, reporting classical ideas on salivary gland physiology and recently developed technology to guide regeneration, reconstruction and substitution of the functional organs. Full article
(This article belongs to the Special Issue Stem Cell Therapy in Oral and Maxillofacial Region)
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Open AccessEditor’s ChoiceReview
TGFβ/BMP Signaling Pathway in Cartilage Homeostasis
Cells 2019, 8(9), 969; https://doi.org/10.3390/cells8090969 - 24 Aug 2019
Cited by 24
Abstract
Cartilage homeostasis is governed by articular chondrocytes via their ability to modulate extracellular matrix production and degradation. In turn, chondrocyte activity is regulated by growth factors such as those of the transforming growth factor β (TGFβ) family. Members of this family include the [...] Read more.
Cartilage homeostasis is governed by articular chondrocytes via their ability to modulate extracellular matrix production and degradation. In turn, chondrocyte activity is regulated by growth factors such as those of the transforming growth factor β (TGFβ) family. Members of this family include the TGFβs, bone morphogenetic proteins (BMPs), and growth and differentiation factors (GDFs). Signaling by this protein family uniquely activates SMAD-dependent signaling and transcription but also activates SMAD-independent signaling via MAPKs such as ERK and TAK1. This review will address the pivotal role of the TGFβ family in cartilage biology by listing several TGFβ family members and describing their signaling and importance for cartilage maintenance. In addition, it is discussed how (pathological) processes such as aging, mechanical stress, and inflammation contribute to altered TGFβ family signaling, leading to disturbed cartilage metabolism and disease. Full article
(This article belongs to the Special Issue TGF-beta/BMP Signaling Pathway)
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Open AccessFeature PaperEditor’s ChoiceReview
Dynamics of Dynamin-Related Protein 1 in Alzheimer’s Disease and Other Neurodegenerative Diseases
Cells 2019, 8(9), 961; https://doi.org/10.3390/cells8090961 - 23 Aug 2019
Cited by 32
Abstract
The purpose of this article is to highlight the role of dynamin-related protein 1 (Drp1) in abnormal mitochondrial dynamics, mitochondrial fragmentation, autophagy/mitophagy, and neuronal damage in Alzheimer’s disease (AD) and other neurological diseases, including Parkinson’s, Huntington’s, amyotrophic lateral sclerosis, multiple sclerosis, diabetes, and [...] Read more.
The purpose of this article is to highlight the role of dynamin-related protein 1 (Drp1) in abnormal mitochondrial dynamics, mitochondrial fragmentation, autophagy/mitophagy, and neuronal damage in Alzheimer’s disease (AD) and other neurological diseases, including Parkinson’s, Huntington’s, amyotrophic lateral sclerosis, multiple sclerosis, diabetes, and obesity. Dynamin-related protein 1 is one of the evolutionarily highly conserved large family of GTPase proteins. Drp1 is critical for mitochondrial division, size, shape, and distribution throughout the neuron, from cell body to axons, dendrites, and nerve terminals. Several decades of intense research from several groups revealed that Drp1 is enriched at neuronal terminals and involved in synapse formation and synaptic sprouting. Different phosphorylated forms of Drp1 acts as both increased fragmentation and/or increased fusion of mitochondria. Increased levels of Drp1 were found in diseased states and caused excessive fragmentation of mitochondria, leading to mitochondrial dysfunction and neuronal damage. In the last two decades, several Drp1 inhibitors have been developed, including Mdivi-1, Dynasore, P110, and DDQ and their beneficial effects tested using cell cultures and mouse models of neurodegenerative diseases. Recent research using genetic crossing studies revealed that a partial reduction of Drp1 is protective against mutant protein(s)-induced mitochondrial and synaptic toxicities. Based on findings from cell cultures, mouse models and postmortem brains of AD and other neurodegenerative disease, we cautiously conclude that reduced Drp1 is a promising therapeutic target for AD and other neurological diseases. Full article
(This article belongs to the Special Issue Mitochondrial Dynamics: Fusion and Fission)
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Open AccessEditor’s ChoiceReview
Mechanisms of Chemotherapy Resistance in Triple-Negative Breast Cancer—How We Can Rise to the Challenge
Cells 2019, 8(9), 957; https://doi.org/10.3390/cells8090957 - 22 Aug 2019
Cited by 56
Abstract
Triple-negative (TNBC) is the most lethal subtype of breast cancer owing to high heterogeneity, aggressive nature, and lack of treatment options. Chemotherapy remains the standard of care for TNBC treatment, but unfortunately, patients frequently develop resistance. Accordingly, in recent years, tremendous effort has [...] Read more.
Triple-negative (TNBC) is the most lethal subtype of breast cancer owing to high heterogeneity, aggressive nature, and lack of treatment options. Chemotherapy remains the standard of care for TNBC treatment, but unfortunately, patients frequently develop resistance. Accordingly, in recent years, tremendous effort has been made into elucidating the mechanisms of TNBC chemoresistance with the goal of identifying new molecular targets. It has become evident that the development of TNBC chemoresistance is multifaceted and based on the elaborate interplay of the tumor microenvironment, drug efflux, cancer stem cells, and bulk tumor cells. Alterations of multiple signaling pathways govern these interactions. Moreover, TNBC’s high heterogeneity, highlighted in the existence of several molecular signatures, presents a significant obstacle to successful treatment. In the present, in-depth review, we explore the contribution of key mechanisms to TNBC chemoresistance as well as emerging strategies to overcome them. We discuss novel anti-tumor agents that target the components of these mechanisms and pay special attention to their current clinical development while emphasizing the challenges still ahead of successful TNBC management. The evidence presented in this review outlines the role of crucial pathways in TNBC survival following chemotherapy treatment and highlights the importance of using combinatorial drug strategies and incorporating biomarkers in clinical studies. Full article
(This article belongs to the Special Issue Molecular and Cellular Mechanisms of Cancers: Breast Cancer)
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Open AccessEditor’s ChoiceReview
The Intricate Interplay between Epigenetic Events, Alternative Splicing and Noncoding RNA Deregulation in Colorectal Cancer
Cells 2019, 8(8), 929; https://doi.org/10.3390/cells8080929 - 19 Aug 2019
Cited by 8
Abstract
Colorectal cancer (CRC) results from a transformation of colonic epithelial cells into adenocarcinoma cells due to genetic and epigenetic instabilities, alongside remodelling of the surrounding stromal tumour microenvironment. Epithelial-specific epigenetic variations escorting this process include chromatin remodelling, histone modifications and aberrant DNA methylation, [...] Read more.
Colorectal cancer (CRC) results from a transformation of colonic epithelial cells into adenocarcinoma cells due to genetic and epigenetic instabilities, alongside remodelling of the surrounding stromal tumour microenvironment. Epithelial-specific epigenetic variations escorting this process include chromatin remodelling, histone modifications and aberrant DNA methylation, which influence gene expression, alternative splicing and function of non-coding RNA. In this review, we first highlight epigenetic modulators, modifiers and mediators in CRC, then we elaborate on causes and consequences of epigenetic alterations in CRC pathogenesis alongside an appraisal of the complex feedback mechanisms realized through alternative splicing and non-coding RNA regulation. An emphasis in our review is put on how this intricate network of epigenetic and post-transcriptional gene regulation evolves during the initiation, progression and metastasis formation in CRC. Full article
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Open AccessFeature PaperEditor’s ChoiceReview
Characterization of Cell Glycocalyx with Mass Spectrometry Methods
Cells 2019, 8(8), 882; https://doi.org/10.3390/cells8080882 - 13 Aug 2019
Cited by 10
Abstract
The cell membrane plays an important role in protecting the cell from its extracellular environment. As such, extensive work has been devoted to studying its structure and function. Crucial intercellular processes, such as signal transduction and immune protection, are mediated by cell surface [...] Read more.
The cell membrane plays an important role in protecting the cell from its extracellular environment. As such, extensive work has been devoted to studying its structure and function. Crucial intercellular processes, such as signal transduction and immune protection, are mediated by cell surface glycosylation, which is comprised of large biomolecules, including glycoproteins and glycosphingolipids. Because perturbations in glycosylation could result in dysfunction of cells and are related to diseases, the analysis of surface glycosylation is critical for understanding pathogenic mechanisms and can further lead to biomarker discovery. Different mass spectrometry-based techniques have been developed for glycan analysis, ranging from highly specific, targeted approaches to more comprehensive profiling studies. In this review, we summarized the work conducted for extensive analysis of cell membrane glycosylation, particularly those employing liquid chromatography with mass spectrometry (LC-MS) in combination with various sample preparation techniques. Full article
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Open AccessEditor’s ChoiceReview
Current and Future Trends on Diagnosis and Prognosis of Glioblastoma: From Molecular Biology to Proteomics
Cells 2019, 8(8), 863; https://doi.org/10.3390/cells8080863 - 09 Aug 2019
Cited by 39
Abstract
Glioblastoma multiforme is the most aggressive malignant tumor of the central nervous system. Due to the absence of effective pharmacological and surgical treatments, the identification of early diagnostic and prognostic biomarkers is of key importance to improve the survival rate of patients and [...] Read more.
Glioblastoma multiforme is the most aggressive malignant tumor of the central nervous system. Due to the absence of effective pharmacological and surgical treatments, the identification of early diagnostic and prognostic biomarkers is of key importance to improve the survival rate of patients and to develop new personalized treatments. On these bases, the aim of this review article is to summarize the current knowledge regarding the application of molecular biology and proteomics techniques for the identification of novel biomarkers through the analysis of different biological samples obtained from glioblastoma patients, including DNA, microRNAs, proteins, small molecules, circulating tumor cells, extracellular vesicles, etc. Both benefits and pitfalls of molecular biology and proteomics analyses are discussed, including the different mass spectrometry-based analytical techniques, highlighting how these investigation strategies are powerful tools to study the biology of glioblastoma, as well as to develop advanced methods for the management of this pathology. Full article
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Open AccessEditor’s ChoiceReview
Current Status in Testing for Nonalcoholic Fatty Liver Disease (NAFLD) and Nonalcoholic Steatohepatitis (NASH)
Cells 2019, 8(8), 845; https://doi.org/10.3390/cells8080845 - 07 Aug 2019
Cited by 32
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western countries with almost 25% affected adults worldwide. The growing public health burden is getting evident when considering that NAFLD-related liver transplantations are predicted to almost double within the next [...] Read more.
Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western countries with almost 25% affected adults worldwide. The growing public health burden is getting evident when considering that NAFLD-related liver transplantations are predicted to almost double within the next 20 years. Typically, hepatic alterations start with simple steatosis, which easily progresses to more advanced stages such as nonalcoholic steatohepatitis (NASH), fibrosis and cirrhosis. This course of disease finally leads to end-stage liver disease such as hepatocellular carcinoma, which is associated with increased morbidity and mortality. Although clinical trials show promising results, there is actually no pharmacological agent approved to treat NASH. Another important problem associated with NASH is that presently the liver biopsy is still the gold standard in diagnosis and for disease staging and grading. Because of its invasiveness, this technique is not well accepted by patients and the method is prone to sampling error. Therefore, an urgent need exists to find reliable, accurate and noninvasive biomarkers discriminating between different disease stages or to develop innovative imaging techniques to quantify steatosis. Full article
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Open AccessEditor’s ChoiceReview
Role of miRNA-Regulated Cancer Stem Cells in the Pathogenesis of Human Malignancies
Cells 2019, 8(8), 840; https://doi.org/10.3390/cells8080840 - 05 Aug 2019
Cited by 40
Abstract
Recent biomedical discoveries have revolutionized the concept and understanding of carcinogenesis, a complex and multistep phenomenon which involves accretion of genetic, epigenetic, biochemical, and histological changes, with special reference to MicroRNAs (miRNAs) and cancer stem cells (CSCs). miRNAs are small noncoding molecules known [...] Read more.
Recent biomedical discoveries have revolutionized the concept and understanding of carcinogenesis, a complex and multistep phenomenon which involves accretion of genetic, epigenetic, biochemical, and histological changes, with special reference to MicroRNAs (miRNAs) and cancer stem cells (CSCs). miRNAs are small noncoding molecules known to regulate expression of more than 60% of the human genes, and their aberrant expression has been associated with the pathogenesis of human cancers and the regulation of stemness features of CSCs. CSCs are the small population of cells present in human malignancies well-known for cancer resistance, relapse, tumorigenesis, and poor clinical outcome which compels the development of novel and effective therapeutic protocols for better clinical outcome. Interestingly, the role of miRNAs in maintaining and regulating the functioning of CSCs through targeting various oncogenic signaling pathways, such as Notch, wingless (WNT)/β-Catenin, janus kinases/ signal transducer and activator of transcription (JAK/STAT), phosphatidylinositol 3-kinase/ protein kinase B (PI3/AKT), and nuclear factor kappa-light-chain-enhancer of activated B (NF-kB), is critical and poses a huge challenge to cancer treatment. Based on recent findings, here, we have documented the regulatory action or the underlying mechanisms of how miRNAs affect the signaling pathways attributed to stemness features of CSCs, such as self-renewal, differentiation, epithelial to mesenchymal transition (EMT), metastasis, resistance and recurrence etc., associated with the pathogenesis of various types of human malignancies including colorectal cancer, lung cancer, breast cancer, head and neck cancer, prostate cancer, liver cancer, etc. We also shed light on the fact that the targeted attenuation of deregulated functioning of miRNA related to stemness in human carcinogenesis could be a viable approach for cancer treatment. Full article
(This article belongs to the Special Issue CSCs Identification and Targeting Therapies: Advances and Challenges)
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Open AccessEditor’s ChoiceReview
WNT Signaling in Disease
Cells 2019, 8(8), 826; https://doi.org/10.3390/cells8080826 - 03 Aug 2019
Cited by 36
Abstract
Developmental signaling pathways control a vast array of biological processes during embryogenesis and in adult life. The WNT pathway was discovered simultaneously in cancer and development. Recent advances have expanded the role of WNT to a wide range of pathologies in humans. Here, [...] Read more.
Developmental signaling pathways control a vast array of biological processes during embryogenesis and in adult life. The WNT pathway was discovered simultaneously in cancer and development. Recent advances have expanded the role of WNT to a wide range of pathologies in humans. Here, we discuss the WNT pathway and its role in human disease and some of the advances in WNT-related treatments. Full article
(This article belongs to the Special Issue Wnt Signaling in Health and Diseases)
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Open AccessEditor’s ChoiceReview
Metabolic Plasticity of Acute Myeloid Leukemia
Cells 2019, 8(8), 805; https://doi.org/10.3390/cells8080805 - 31 Jul 2019
Cited by 20
Abstract
Acute myeloid leukemia (AML) is one of the most common and life-threatening leukemias. A highly diverse and flexible metabolism contributes to the aggressiveness of the disease that is still difficult to treat. By using different sources of nutrients for energy and biomass supply, [...] Read more.
Acute myeloid leukemia (AML) is one of the most common and life-threatening leukemias. A highly diverse and flexible metabolism contributes to the aggressiveness of the disease that is still difficult to treat. By using different sources of nutrients for energy and biomass supply, AML cells gain metabolic plasticity and rapidly outcompete normal hematopoietic cells. This review aims to decipher the diverse metabolic strategies and the underlying oncogenic and environmental changes that sustain continuous growth, mediate redox homeostasis and induce drug resistance in AML. We revisit Warburg’s hypothesis and illustrate the role of glucose as a provider of cellular building blocks rather than as a supplier of the tricarboxylic acid (TCA) cycle for energy production. We discuss how the diversity of fuels for the TCA cycle, including glutamine and fatty acids, contributes to the metabolic plasticity of the disease and highlight the roles of amino acids and lipids in AML metabolism. Furthermore, we point out the potential of the different metabolic effectors to be used as novel therapeutic targets. Full article
(This article belongs to the Special Issue Metabolomics in Physiology and Diseases)
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Open AccessEditor’s ChoiceReview
Role and Therapeutic Targeting of the PI3K/Akt/mTOR Signaling Pathway in Skin Cancer: A Review of Current Status and Future Trends on Natural and Synthetic Agents Therapy
Cells 2019, 8(8), 803; https://doi.org/10.3390/cells8080803 - 31 Jul 2019
Cited by 28
Abstract
The mammalian or mechanistic target of rapamycin (mTOR) and associated phosphatidyl-inositiol 3-kinase (PI3K)/protein kinase B (Akt) pathways regulate cell growth, differentiation, migration, and survival, as well as angiogenesis and metabolism. Dysregulation of these pathways is frequently associated with genetic/epigenetic alterations and predicts poor [...] Read more.
The mammalian or mechanistic target of rapamycin (mTOR) and associated phosphatidyl-inositiol 3-kinase (PI3K)/protein kinase B (Akt) pathways regulate cell growth, differentiation, migration, and survival, as well as angiogenesis and metabolism. Dysregulation of these pathways is frequently associated with genetic/epigenetic alterations and predicts poor treatment outcomes in a variety of human cancers including cutaneous malignancies like melanoma and non-melanoma skin cancers. Recently, the enhanced understanding of the molecular and genetic basis of skin dysfunction in patients with skin cancers has provided a strong basis for the development of novel therapeutic strategies for these obdurate groups of skin cancers. This review summarizes recent advances in the roles of PI3K/Akt/mTOR and their targets in the development and progression of a broad spectrum of cutaneous cancers and discusses the current progress in preclinical and clinical studies for the development of PI3K/Akt/mTOR targeted therapies with nutraceuticals and synthetic small molecule inhibitors. Full article
(This article belongs to the Special Issue mTOR Signaling in Metabolism and Cancer) Printed Edition available
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Short Overview of ROS as Cell Function Regulators and Their Implications in Therapy Concepts
Cells 2019, 8(8), 793; https://doi.org/10.3390/cells8080793 - 30 Jul 2019
Cited by 38
Abstract
The importance of reactive oxygen species (ROS) has been gradually acknowledged over the last four decades. Initially perceived as unwanted products of detrimental oxidative stress, they have been upgraded since, and now ROS are also known to be essential for the regulation of [...] Read more.
The importance of reactive oxygen species (ROS) has been gradually acknowledged over the last four decades. Initially perceived as unwanted products of detrimental oxidative stress, they have been upgraded since, and now ROS are also known to be essential for the regulation of physiological cellular functions through redox signaling. In the majority of cases, metabolic demands, along with other stimuli, are vital for ROS formation and their actions. In this review, we focus on the role of ROS in regulating cell functioning and communication among themselves. The relevance of ROS in therapy concepts is also addressed here. Full article
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Metabolic Dysregulations and Epigenetics: A Bidirectional Interplay that Drives Tumor Progression
Cells 2019, 8(8), 798; https://doi.org/10.3390/cells8080798 - 30 Jul 2019
Cited by 10
Abstract
Cancer has been considered, for a long time, a genetic disease where mutations in key regulatory genes drive tumor initiation, growth, metastasis, and drug resistance. Instead, the advent of high-throughput technologies has revolutionized cancer research, allowing to investigate molecular alterations at multiple levels, [...] Read more.
Cancer has been considered, for a long time, a genetic disease where mutations in key regulatory genes drive tumor initiation, growth, metastasis, and drug resistance. Instead, the advent of high-throughput technologies has revolutionized cancer research, allowing to investigate molecular alterations at multiple levels, including genome, epigenome, transcriptome, proteome, and metabolome and showing the multifaceted aspects of this disease. The multi-omics approaches revealed an intricate molecular landscape where different cellular functions are interconnected and cooperatively contribute to shaping the malignant phenotype. Recent evidence has brought to light how metabolism and epigenetics are highly intertwined, and their aberrant crosstalk can contribute to tumorigenesis. The oncogene-driven metabolic plasticity of tumor cells supports the energetic and anabolic demands of proliferative tumor programs and secondary can alter the epigenetic landscape via modulating the production and/or the activity of epigenetic metabolites. Conversely, epigenetic mechanisms can regulate the expression of metabolic genes, thereby altering the metabolome, eliciting adaptive responses to rapidly changing environmental conditions, and sustaining malignant cell survival and progression in hostile niches. Thus, cancer cells take advantage of the epigenetics-metabolism crosstalk to acquire aggressive traits, promote cell proliferation, metastasis, and pluripotency, and shape tumor microenvironment. Understanding this bidirectional relationship is crucial to identify potential novel molecular targets for the implementation of robust anti-cancer therapeutic strategies. Full article
(This article belongs to the Special Issue Mitochondrial Metabolic Reprogramming and Nuclear Crosstalk in Cancer)
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Targeting the Canonical WNT/β-Catenin Pathway in Cancer Treatment Using Non-Steroidal Anti-Inflammatory Drugs
Cells 2019, 8(7), 726; https://doi.org/10.3390/cells8070726 - 15 Jul 2019
Cited by 22
Abstract
Chronic inflammation and oxidative stress are common and co-substantial pathological processes accompanying and contributing to cancers. Numerous epidemiological studies have indicated that non-steroidal anti-inflammatory drugs (NSAIDs) could have a positive effect on both the prevention of cancer and tumor therapy. Numerous hypotheses have [...] Read more.
Chronic inflammation and oxidative stress are common and co-substantial pathological processes accompanying and contributing to cancers. Numerous epidemiological studies have indicated that non-steroidal anti-inflammatory drugs (NSAIDs) could have a positive effect on both the prevention of cancer and tumor therapy. Numerous hypotheses have postulated that NSAIDs could slow tumor growth by acting on both chronic inflammation and oxidative stress. This review takes a closer look at these hypotheses. In the cancer process, one of the major signaling pathways involved is the WNT/β-catenin pathway, which appears to be upregulated. This pathway is closely associated with both chronic inflammation and oxidative stress in cancers. The administration of NSAIDs has been observed to help in the downregulation of the WNT/β-catenin pathway and thus in the control of tumor growth. NSAIDs act as PPARγ agonists. The WNT/β-catenin pathway and PPARγ act in opposing manners. PPARγ agonists can promote cell cycle arrest, cell differentiation, and apoptosis, and can reduce inflammation, oxidative stress, proliferation, invasion, and cell migration. In parallel, the dysregulation of circadian rhythms (CRs) contributes to cancer development through the upregulation of the canonical WNT/β-catenin pathway. By stimulating PPARγ expression, NSAIDs can control CRs through the regulation of many key circadian genes. The administration of NSAIDs in cancer treatment would thus appear to be an interesting therapeutic strategy, which acts through their role in regulating WNT/β-catenin pathway and PPARγ activity levels. Full article
(This article belongs to the Special Issue Wnt Signaling in Health and Diseases)
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Overview of Extracellular Vesicles, Their Origin, Composition, Purpose, and Methods for Exosome Isolation and Analysis
Cells 2019, 8(7), 727; https://doi.org/10.3390/cells8070727 - 15 Jul 2019
Cited by 183
Abstract
The use of extracellular vesicles, specifically exosomes, as carriers of biomarkers in extracellular spaces has been well demonstrated. Despite their promising potential, the use of exosomes in the clinical setting is restricted due to the lack of standardization in exosome isolation and analysis [...] Read more.
The use of extracellular vesicles, specifically exosomes, as carriers of biomarkers in extracellular spaces has been well demonstrated. Despite their promising potential, the use of exosomes in the clinical setting is restricted due to the lack of standardization in exosome isolation and analysis methods. The purpose of this review is to not only introduce the different types of extracellular vesicles but also to summarize their differences and similarities, and discuss different methods of exosome isolation and analysis currently used. A thorough understanding of the isolation and analysis methods currently being used could lead to some standardization in the field of exosomal research, allowing the use of exosomes in the clinical setting to become a reality. Full article
(This article belongs to the Special Issue Exosomes and Extracellular Vesicles in Health and Disease)
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Open AccessEditor’s ChoiceReview
Never Travel Alone: The Crosstalk of Circulating Tumor Cells and the Blood Microenvironment
Cells 2019, 8(7), 714; https://doi.org/10.3390/cells8070714 - 13 Jul 2019
Cited by 22
Abstract
Commonly, circulating tumor cells (CTCs) are described as source of metastasis in cancer patients. However, in this process cancer cells of the primary tumor site need to survive the physical and biological challenges in the blood stream before leaving the circulation to become [...] Read more.
Commonly, circulating tumor cells (CTCs) are described as source of metastasis in cancer patients. However, in this process cancer cells of the primary tumor site need to survive the physical and biological challenges in the blood stream before leaving the circulation to become the seed of a new metastatic site in distant parenchyma. Most of the CTCs released in the blood stream will not resist those challenges and will consequently fail to induce metastasis. A few of them, however, interact closely with other blood cells, such as neutrophils, platelets, and/or macrophages to survive in the blood stream. Recent studies demonstrated that the interaction and modulation of the blood microenvironment by CTCs is pivotal for the development of new metastasis, making it an interesting target for potential novel treatment strategies. This review will discuss the recent research on the processes in the blood microenvironment with CTCs and will outline currently investigated treatment strategies. Full article
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Mitochondrial Homeostasis and Cellular Senescence
Cells 2019, 8(7), 686; https://doi.org/10.3390/cells8070686 - 06 Jul 2019
Cited by 33
Abstract
Cellular senescence refers to a stress response aiming to preserve cellular and, therefore, organismal homeostasis. Importantly, deregulation of mitochondrial homeostatic mechanisms, manifested as impaired mitochondrial biogenesis, metabolism and dynamics, has emerged as a hallmark of cellular senescence. On the other hand, impaired mitostasis [...] Read more.
Cellular senescence refers to a stress response aiming to preserve cellular and, therefore, organismal homeostasis. Importantly, deregulation of mitochondrial homeostatic mechanisms, manifested as impaired mitochondrial biogenesis, metabolism and dynamics, has emerged as a hallmark of cellular senescence. On the other hand, impaired mitostasis has been suggested to induce cellular senescence. This review aims to provide an overview of homeostatic mechanisms operating within mitochondria and a comprehensive insight into the interplay between cellular senescence and mitochondrial dysfunction. Full article
(This article belongs to the Special Issue Mitochondrial Genetics)
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Melatonin in Medicinal and Food Plants: Occurrence, Bioavailability, and Health Potential for Humans
Cells 2019, 8(7), 681; https://doi.org/10.3390/cells8070681 - 05 Jul 2019
Cited by 31
Abstract
Melatonin is a widespread molecule among living organisms involved in multiple biological, hormonal, and physiological processes at cellular, tissue, and organic levels. It is well-known for its ability to cross the blood–brain barrier, and renowned antioxidant effects, acting as a free radical scavenger, [...] Read more.
Melatonin is a widespread molecule among living organisms involved in multiple biological, hormonal, and physiological processes at cellular, tissue, and organic levels. It is well-known for its ability to cross the blood–brain barrier, and renowned antioxidant effects, acting as a free radical scavenger, up-regulating antioxidant enzymes, reducing mitochondrial electron leakage, and interfering with proinflammatory signaling pathways. Detected in various medicinal and food plants, its concentration is widely variable. Plant generative organs (e.g., flowers, fruits), and especially seeds, have been proposed as having the highest melatonin concentrations, markedly higher than those found in vertebrate tissues. In addition, seeds are also rich in other substances (lipids, sugars, and proteins), constituting the energetic reserve for a potentially growing seedling and beneficial for the human diet. Thus, given that dietary melatonin is absorbed in the gastrointestinal tract and transported into the bloodstream, the ingestion of medicinal and plant foods by mammals as a source of melatonin may be conceived as a key step in serum melatonin modulation and, consequently, health promotion. Full article
(This article belongs to the Special Issue Melatonin in Human Health and Diseases)
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Myasthenia Gravis: Pathogenic Effects of Autoantibodies on Neuromuscular Architecture
Cells 2019, 8(7), 671; https://doi.org/10.3390/cells8070671 - 02 Jul 2019
Cited by 23
Abstract
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction (NMJ). Autoantibodies target key molecules at the NMJ, such as the nicotinic acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low-density lipoprotein receptor-related protein 4 (Lrp4), that lead by a range of different [...] Read more.
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction (NMJ). Autoantibodies target key molecules at the NMJ, such as the nicotinic acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low-density lipoprotein receptor-related protein 4 (Lrp4), that lead by a range of different pathogenic mechanisms to altered tissue architecture and reduced densities or functionality of AChRs, reduced neuromuscular transmission, and therefore a severe fatigable skeletal muscle weakness. In this review, we give an overview of the history and clinical aspects of MG, with a focus on the structure and function of myasthenic autoantigens at the NMJ and how they are affected by the autoantibodies’ pathogenic mechanisms. Furthermore, we give a short overview of the cells that are implicated in the production of the autoantibodies and briefly discuss diagnostic challenges and treatment strategies. Full article
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Open AccessEditor’s ChoiceReview
Patient-Derived Xenograft Models of Breast Cancer and Their Application
Cells 2019, 8(6), 621; https://doi.org/10.3390/cells8060621 - 20 Jun 2019
Cited by 15
Abstract
Recently, patient-derived xenograft (PDX) models of many types of tumors including breast cancer have emerged as a powerful tool for predicting drug efficacy and for understanding tumor characteristics. PDXs are established by the direct transfer of human tumors into highly immunodeficient mice and [...] Read more.
Recently, patient-derived xenograft (PDX) models of many types of tumors including breast cancer have emerged as a powerful tool for predicting drug efficacy and for understanding tumor characteristics. PDXs are established by the direct transfer of human tumors into highly immunodeficient mice and then maintained by passaging from mouse to mouse. The ability of PDX models to maintain the original features of patient tumors and to reflect drug sensitivity has greatly improved both basic and clinical study outcomes. However, current PDX models cannot completely predict drug efficacy because they do not recapitulate the tumor microenvironment of origin, a failure which puts emphasis on the necessity for the development of the next generation PDX models. In this article, we summarize the advantages and limitations of current PDX models and discuss the future directions of this field. Full article
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Regulation of TEAD Transcription Factors in Cancer Biology
Cells 2019, 8(6), 600; https://doi.org/10.3390/cells8060600 - 17 Jun 2019
Cited by 32
Abstract
Transcriptional enhanced associate domain (TEAD) transcription factors play important roles during development, cell proliferation, regeneration, and tissue homeostasis. TEAD integrates with and coordinates various signal transduction pathways including Hippo, Wnt, transforming growth factor beta (TGFβ), and epidermal growth factor receptor (EGFR) pathways. TEAD [...] Read more.
Transcriptional enhanced associate domain (TEAD) transcription factors play important roles during development, cell proliferation, regeneration, and tissue homeostasis. TEAD integrates with and coordinates various signal transduction pathways including Hippo, Wnt, transforming growth factor beta (TGFβ), and epidermal growth factor receptor (EGFR) pathways. TEAD deregulation affects well-established cancer genes such as KRAS, BRAF, LKB1, NF2, and MYC, and its transcriptional output plays an important role in tumor progression, metastasis, cancer metabolism, immunity, and drug resistance. To date, TEADs have been recognized to be key transcription factors of the Hippo pathway. Therefore, most studies are focused on the Hippo kinases and YAP/TAZ, whereas the Hippo-dependent and Hippo-independent regulators and regulations governing TEAD only emerged recently. Deregulation of the TEAD transcriptional output plays important roles in tumor progression and serves as a prognostic biomarker due to high correlation with clinicopathological parameters in human malignancies. In addition, discovering the molecular mechanisms of TEAD, such as post-translational modifications and nucleocytoplasmic shuttling, represents an important means of modulating TEAD transcriptional activity. Collectively, this review highlights the role of TEAD in multistep-tumorigenesis by interacting with upstream oncogenic signaling pathways and controlling downstream target genes, which provides unprecedented insight and rationale into developing TEAD-targeted anticancer therapeutics. Full article
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Open AccessFeature PaperEditor’s ChoiceReview
Genome Organization in and around the Nucleolus
Cells 2019, 8(6), 579; https://doi.org/10.3390/cells8060579 - 12 Jun 2019
Cited by 30
Abstract
The nucleolus is the largest substructure in the nucleus, where ribosome biogenesis takes place, and forms around the nucleolar organizer regions (NORs) that comprise ribosomal RNA (rRNA) genes. Each cell contains hundreds of rRNA genes, which are organized in three distinct chromatin and [...] Read more.
The nucleolus is the largest substructure in the nucleus, where ribosome biogenesis takes place, and forms around the nucleolar organizer regions (NORs) that comprise ribosomal RNA (rRNA) genes. Each cell contains hundreds of rRNA genes, which are organized in three distinct chromatin and transcriptional states—silent, inactive and active. Increasing evidence indicates that the role of the nucleolus and rRNA genes goes beyond the control of ribosome biogenesis. Recent results highlighted the nucleolus as a compartment for the location and regulation of repressive genomic domains and, together with the nuclear lamina, represents the hub for the organization of the inactive heterochromatin. In this review, we aim to describe the crosstalk between the nucleolus and the rest of the genome and how distinct rRNA gene chromatin states affect nucleolus structure and are implicated in genome stability, genome architecture, and cell fate decision. Full article
(This article belongs to the Special Issue Nucleolar Organization and Functions in Health and Disease)
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Open AccessEditor’s ChoiceReview
Insights on CTC Biology and Clinical Impact Emerging from Advances in Capture Technology
Cells 2019, 8(6), 553; https://doi.org/10.3390/cells8060553 - 06 Jun 2019
Cited by 15
Abstract
Circulating tumor cells (CTCs) and circulating tumor microemboli (CTM) have been shown to correlate negatively with patient survival. Actual CTC counts before and after treatment can be used to aid in the prognosis of patient outcomes. The presence of circulating tumor materials (CTMat) [...] Read more.
Circulating tumor cells (CTCs) and circulating tumor microemboli (CTM) have been shown to correlate negatively with patient survival. Actual CTC counts before and after treatment can be used to aid in the prognosis of patient outcomes. The presence of circulating tumor materials (CTMat) can advertise the presence of metastasis before clinical presentation, enabling the early detection of relapse. Importantly, emerging evidence is indicating that cancer treatments can actually increase the incidence of CTCs and metastasis in pre-clinical models. Subsequently, the study of CTCs, their biology and function are of vital importance. Emerging technologies for the capture of CTC/CTMs and CTMat are elucidating vitally important biological and functional information that can lead to important alterations in how therapies are administered. This paves the way for the development of a “liquid biopsy” where treatment decisions can be informed by information gleaned from tumor cells and tumor cell debris in the blood. Full article
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Open AccessEditor’s ChoiceReview
Glycosylation in the Tumor Microenvironment: Implications for Tumor Angiogenesis and Metastasis
Cells 2019, 8(6), 544; https://doi.org/10.3390/cells8060544 - 05 Jun 2019
Cited by 14
Abstract
Just as oncogene activation and tumor suppressor loss are hallmarks of tumor development, emerging evidence indicates that tumor microenvironment-mediated changes in glycosylation play a crucial functional role in tumor progression and metastasis. Hypoxia and inflammatory events regulate protein glycosylation in tumor cells and [...] Read more.
Just as oncogene activation and tumor suppressor loss are hallmarks of tumor development, emerging evidence indicates that tumor microenvironment-mediated changes in glycosylation play a crucial functional role in tumor progression and metastasis. Hypoxia and inflammatory events regulate protein glycosylation in tumor cells and associated stromal cells in the tumor microenvironment, which facilitates tumor progression and also modulates a patient’s response to anti-cancer therapeutics. In this review, we highlight the impact of altered glycosylation on angiogenic signaling and endothelial cell adhesion, and the critical consequences of these changes in tumor behavior. Full article
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Recent Data on Cellular Component Turnover: Focus on Adaptations to Physical Exercise
Cells 2019, 8(6), 542; https://doi.org/10.3390/cells8060542 - 05 Jun 2019
Cited by 15
Abstract
Significant progress has expanded our knowledge of the signaling pathways coordinating muscle protein turnover during various conditions including exercise. In this manuscript, the multiple mechanisms that govern the turnover of cellular components are reviewed, and their overall roles in adaptations to exercise training [...] Read more.
Significant progress has expanded our knowledge of the signaling pathways coordinating muscle protein turnover during various conditions including exercise. In this manuscript, the multiple mechanisms that govern the turnover of cellular components are reviewed, and their overall roles in adaptations to exercise training are discussed. Recent studies have highlighted the central role of the energy sensor (AMP)-activated protein kinase (AMPK), forkhead box class O subfamily protein (FOXO) transcription factors and the kinase mechanistic (or mammalian) target of rapamycin complex (MTOR) in the regulation of autophagy for organelle maintenance during exercise. A new cellular trafficking involving the lysosome was also revealed for full activation of MTOR and protein synthesis during recovery. Other emerging candidates have been found to be relevant in organelle turnover, especially Parkin and the mitochondrial E3 ubiquitin protein ligase (Mul1) pathways for mitochondrial turnover, and the glycerolipids diacylglycerol (DAG) for protein translation and FOXO regulation. Recent experiments with autophagy and mitophagy flux assessment have also provided important insights concerning mitochondrial turnover during ageing and chronic exercise. However, data in humans are often controversial and further investigations are needed to clarify the involvement of autophagy in exercise performed with additional stresses, such as hypoxia, and to understand the influence of exercise modality. Improving our knowledge of these pathways should help develop therapeutic ways to counteract muscle disorders in pathological conditions. Full article
(This article belongs to the Special Issue Autophagy in Tissue Injury and Homeostasis) Printed Edition available
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Open AccessEditor’s ChoiceReview
Current Status of Patient-Derived Ovarian Cancer Models
Cells 2019, 8(5), 505; https://doi.org/10.3390/cells8050505 - 25 May 2019
Cited by 19
Abstract
Ovarian cancer (OC) is one of the leading causes of female cancer death. Recent studies have documented its extensive variations as a disease entity, in terms of cell or tissue of origin, pre-cancerous lesions, common mutations, and therapeutic responses, leading to the notion [...] Read more.
Ovarian cancer (OC) is one of the leading causes of female cancer death. Recent studies have documented its extensive variations as a disease entity, in terms of cell or tissue of origin, pre-cancerous lesions, common mutations, and therapeutic responses, leading to the notion that OC is a generic term referring to a whole range of different cancer subtypes. Despite such heterogeneity, OC treatment is stereotypic; aggressive surgery followed by conventional chemotherapy could result in chemo-resistant diseases. Whereas molecular-targeted therapies will become shortly available for a subset of OC, there still remain many patients without effective drugs, requiring development of groundbreaking therapeutic agents. In preclinical studies for drug discovery, cancer cell lines used to be the gold standard, but now this has declined due to frequent failure in predicting therapeutic responses in patients. In this regard, patient-derived cells and tumors are gaining more attention in precise and physiological modeling of in situ tumors, which could also pave the way to implementation of precision medicine. In this article, we comprehensively overviewed the current status of various platforms for patient-derived OC models. We highly appreciate the potentials of organoid culture in achieving high success rate and retaining tumor heterogeneity. Full article
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Advances in Regenerative Stem Cell Therapy in Androgenic Alopecia and Hair Loss: Wnt Pathway, Growth-Factor, and Mesenchymal Stem Cell Signaling Impact Analysis on Cell Growth and Hair Follicle Development
Cells 2019, 8(5), 466; https://doi.org/10.3390/cells8050466 - 16 May 2019
Cited by 47
Abstract
The use of stem cells has been reported to improve hair regrowth in several therapeutic strategies, including reversing the pathological mechanisms, that contribute to hair loss, regeneration of hair follicles, or creating hair using the tissue-engineering approach. Although various promising stem cell approaches [...] Read more.
The use of stem cells has been reported to improve hair regrowth in several therapeutic strategies, including reversing the pathological mechanisms, that contribute to hair loss, regeneration of hair follicles, or creating hair using the tissue-engineering approach. Although various promising stem cell approaches are progressing via pre-clinical models to clinical trials, intraoperative stem cell treatments with a one-step procedure offer a quicker result by incorporating an autologous cell source without manipulation, which may be injected by surgeons through a well-established clinical practice. Many authors have concentrated on adipose-derived stromal vascular cells due to their ability to separate into numerous cell genealogies, platelet-rich plasma for its ability to enhance cell multiplication and neo-angiogenesis, as well as human follicle mesenchymal stem cells. In this paper, the significant improvements in intraoperative stem cell approaches, from in vivo models to clinical investigations, are reviewed. The potential regenerative instruments and functions of various cell populaces in the hair regrowth process are discussed. The addition of Wnt signaling in dermal papilla cells is considered a key factor in stimulating hair growth. Mesenchymal stem cell-derived signaling and growth factors obtained by platelets influence hair growth through cellular proliferation to prolong the anagen phase (FGF-7), induce cell growth (ERK activation), stimulate hair follicle development (β-catenin), and suppress apoptotic cues (Bcl-2 release and Akt activation). Full article
(This article belongs to the Special Issue Advances in Stem Cells and Regenerative Medicine)
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Molecular Mechanisms Responsible for Therapeutic Potential of Mesenchymal Stem Cell-Derived Secretome
Cells 2019, 8(5), 467; https://doi.org/10.3390/cells8050467 - 16 May 2019
Cited by 66
Abstract
Mesenchymal stem cell (MSC)-sourced secretome, defined as the set of MSC-derived bioactive factors (soluble proteins, nucleic acids, lipids and extracellular vesicles), showed therapeutic effects similar to those observed after transplantation of MSCs. MSC-derived secretome may bypass many side effects of MSC-based therapy, including [...] Read more.
Mesenchymal stem cell (MSC)-sourced secretome, defined as the set of MSC-derived bioactive factors (soluble proteins, nucleic acids, lipids and extracellular vesicles), showed therapeutic effects similar to those observed after transplantation of MSCs. MSC-derived secretome may bypass many side effects of MSC-based therapy, including unwanted differentiation of engrafted MSCs. In contrast to MSCs which had to be expanded in culture to reach optimal cell number for transplantation, MSC-sourced secretome is immediately available for treatment of acute conditions, including fulminant hepatitis, cerebral ischemia and myocardial infarction. Additionally, MSC-derived secretome could be massively produced from commercially available cell lines avoiding invasive cell collection procedure. In this review article we emphasized molecular and cellular mechanisms that were responsible for beneficial effects of MSC-derived secretomes in the treatment of degenerative and inflammatory diseases of hepatobiliary, respiratory, musculoskeletal, gastrointestinal, cardiovascular and nervous system. Results obtained in a large number of studies suggested that administration of MSC-derived secretomes represents a new, cell-free therapeutic approach for attenuation of inflammatory and degenerative diseases. Therapeutic effects of MSC-sourced secretomes relied on their capacity to deliver genetic material, growth and immunomodulatory factors to the target cells enabling activation of anti-apoptotic and pro-survival pathways that resulted in tissue repair and regeneration. Full article
(This article belongs to the Special Issue Immunomodulation by Mesenchymal Stem Cells)
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Hippo Pathway in Mammalian Adaptive Immune System
Cells 2019, 8(5), 398; https://doi.org/10.3390/cells8050398 - 30 Apr 2019
Cited by 19
Abstract
The Hippo pathway was originally identified as an evolutionarily-conserved signaling mechanism that contributes to the control of organ size. It was then rapidly expanded as a key pathway in the regulation of tissue development, regeneration, and cancer pathogenesis. The increasing amount of evidence [...] Read more.
The Hippo pathway was originally identified as an evolutionarily-conserved signaling mechanism that contributes to the control of organ size. It was then rapidly expanded as a key pathway in the regulation of tissue development, regeneration, and cancer pathogenesis. The increasing amount of evidence in recent years has also connected this pathway to the regulation of innate and adaptive immune responses. Notably, the Hippo pathway has been revealed to play a pivotal role in adaptive immune cell lineages, as represented by the patients with T- and B-cell lymphopenia exhibiting defective expressions of the pathway component. The complex regulatory mechanisms of and by the Hippo pathway have also been evident as alternative signal transductions are employed in some immune cell types. In this review article, we summarize the current understanding of the emerging roles of the Hippo pathway in adaptive immune cell development and differentiation. We also highlight the recent findings concerning the dual functions of the Hippo pathway in autoimmunity and anti-cancer immune responses and discuss the key open questions in the interplay between the Hippo pathway and the mammalian immune system. Full article
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Protein Hydroxylation by Hypoxia-Inducible Factor (HIF) Hydroxylases: Unique or Ubiquitous?
Cells 2019, 8(5), 384; https://doi.org/10.3390/cells8050384 - 26 Apr 2019
Cited by 31
Abstract
All metazoans that utilize molecular oxygen (O2) for metabolic purposes have the capacity to adapt to hypoxia, the condition that arises when O2 demand exceeds supply. This is mediated through activation of the hypoxia-inducible factor (HIF) pathway. At physiological oxygen [...] Read more.
All metazoans that utilize molecular oxygen (O2) for metabolic purposes have the capacity to adapt to hypoxia, the condition that arises when O2 demand exceeds supply. This is mediated through activation of the hypoxia-inducible factor (HIF) pathway. At physiological oxygen levels (normoxia), HIF-prolyl hydroxylases (PHDs) hydroxylate proline residues on HIF-α subunits leading to their destabilization by promoting ubiquitination by the von-Hippel Lindau (VHL) ubiquitin ligase and subsequent proteasomal degradation. HIF-α transactivation is also repressed in an O2-dependent way due to asparaginyl hydroxylation by the factor-inhibiting HIF (FIH). In hypoxia, the O2-dependent hydroxylation of HIF-α subunits by PHDs and FIH is reduced, resulting in HIF-α accumulation, dimerization with HIF-β and migration into the nucleus to induce an adaptive transcriptional response. Although HIFs are the canonical substrates for PHD- and FIH-mediated protein hydroxylation, increasing evidence indicates that these hydroxylases may also have alternative targets. In addition to PHD-conferred alterations in protein stability, there is now evidence that hydroxylation can affect protein activity and protein/protein interactions for alternative substrates. PHDs can be pharmacologically inhibited by a new class of drugs termed prolyl hydroxylase inhibitors which have recently been approved for the treatment of anemia associated with chronic kidney disease. The identification of alternative targets of HIF hydroxylases is important in order to fully elucidate the pharmacology of hydroxylase inhibitors (PHI). Despite significant technical advances, screening, detection and verification of alternative functional targets for PHDs and FIH remain challenging. In this review, we discuss recently proposed non-HIF targets for PHDs and FIH and provide an overview of the techniques used to identify these. Full article
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Role of Hedgehog Signaling in Breast Cancer: Pathogenesis and Therapeutics
Cells 2019, 8(4), 375; https://doi.org/10.3390/cells8040375 - 25 Apr 2019
Cited by 24
Abstract
Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include [...] Read more.
Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include personalized targeted therapies. The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. Several lines of evidence endorse the important role of canonical and non-canonical Hh signaling in BC. In this comprehensive review we discuss the role of Hh signaling in breast development and homeostasis and its contribution to tumorigenesis and progression of different subtypes of BC. We also examine the efficacy of agents targeting different components of the Hh pathway both in preclinical models and in clinical trials. The contribution of the Hh pathway in BC tumorigenesis and progression, its prognostic role, and its value as a therapeutic target vary according to the molecular, clinical, and histopathological characteristics of the BC patients. The evidence presented here highlights the relevance of the Hh signaling in BC, and suggest that this pathway is key for BC progression and metastasis. Full article
(This article belongs to the Special Issue Targeting Hedgehog Signaling in Cancer)
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Hepatitis C Virus Infection: Host–Virus Interaction and Mechanisms of Viral Persistence
Cells 2019, 8(4), 376; https://doi.org/10.3390/cells8040376 - 25 Apr 2019
Cited by 21
Abstract
Hepatitis C (HCV) is a major cause of liver disease, in which a third of individuals with chronic HCV infections may develop liver cirrhosis. In a chronic HCV infection, host immune factors along with the actions of HCV proteins that promote viral persistence [...] Read more.
Hepatitis C (HCV) is a major cause of liver disease, in which a third of individuals with chronic HCV infections may develop liver cirrhosis. In a chronic HCV infection, host immune factors along with the actions of HCV proteins that promote viral persistence and dysregulation of the immune system have an impact on immunopathogenesis of HCV-induced hepatitis. The genome of HCV encodes a single polyprotein, which is translated and processed into structural and nonstructural proteins. These HCV proteins are the target of the innate and adaptive immune system of the host. Retinoic acid-inducible gene-I (RIG-I)-like receptors and Toll-like receptors are the main pattern recognition receptors that recognize HCV pathogen-associated molecular patterns. This interaction results in a downstream cascade that generates antiviral cytokines including interferons. The cytolysis of HCV-infected hepatocytes is mediated by perforin and granzyme B secreted by cytotoxic T lymphocyte (CTL) and natural killer (NK) cells, whereas noncytolytic HCV clearance is mediated by interferon gamma (IFN-γ) secreted by CTL and NK cells. A host–HCV interaction determines whether the acute phase of an HCV infection will undergo complete resolution or progress to the development of viral persistence with a consequential progression to chronic HCV infection. Furthermore, these host–HCV interactions could pose a challenge to developing an HCV vaccine. This review will focus on the role of the innate and adaptive immunity in HCV infection, the failure of the immune response to clear an HCV infection, and the factors that promote viral persistence. Full article
(This article belongs to the Special Issue Hepatitis C Virus and Host Interactions)
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Open AccessEditor’s ChoiceReview
Import of Non-Coding RNAs into Human Mitochondria: A Critical Review and Emerging Approaches
Cells 2019, 8(3), 286; https://doi.org/10.3390/cells8030286 - 26 Mar 2019
Cited by 16
Abstract
Mitochondria harbor their own genetic system, yet critically depend on the import of a number of nuclear-encoded macromolecules to ensure their expression. In all eukaryotes, selected non-coding RNAs produced from the nuclear genome are partially redirected into the mitochondria, where they participate in [...] Read more.
Mitochondria harbor their own genetic system, yet critically depend on the import of a number of nuclear-encoded macromolecules to ensure their expression. In all eukaryotes, selected non-coding RNAs produced from the nuclear genome are partially redirected into the mitochondria, where they participate in gene expression. Therefore, the mitochondrial RNome represents an intricate mixture of the intrinsic transcriptome and the extrinsic RNA importome. In this review, we summarize and critically analyze data on the nuclear-encoded transcripts detected in human mitochondria and outline the proposed molecular mechanisms of their mitochondrial import. Special attention is given to the various experimental approaches used to study the mitochondrial RNome, including some recently developed genome-wide and in situ techniques. Full article
(This article belongs to the Special Issue Mitochondrial Genetics)
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Open AccessEditor’s ChoiceReview
Microbiome, Parkinson’s Disease and Molecular Mimicry
Cells 2019, 8(3), 222; https://doi.org/10.3390/cells8030222 - 07 Mar 2019
Cited by 14
Abstract
Parkinson’s Disease (PD) is typically classified as a neurodegenerative disease affecting the motor system. Recent evidence, however, has uncovered the presence of Lewy bodies in locations outside the CNS, in direct contact with the external environment, including the olfactory bulbs and the enteric [...] Read more.
Parkinson’s Disease (PD) is typically classified as a neurodegenerative disease affecting the motor system. Recent evidence, however, has uncovered the presence of Lewy bodies in locations outside the CNS, in direct contact with the external environment, including the olfactory bulbs and the enteric nervous system. This, combined with the ability of alpha-synuclein (αS) to propagate in a prion-like manner, has supported the hypothesis that the resident microbial community, commonly referred to as microbiota, might play a causative role in the development of PD. In this article, we will be reviewing current knowledge on the importance of the microbiota in PD pathology, concentrating our investigation on mechanisms of microbiota-host interactions that might become harmful and favor the onset of PD. Such processes, which include the secretion of bacterial amyloid proteins or other metabolites, may influence the aggregation propensity of αS directly or indirectly, for example by favoring a pro-inflammatory environment in the gut. Thus, while the development of PD has not yet being associated with a unique microbial species, more data will be necessary to examine potential harmful interactions between the microbiota and the host, and to understand their relevance in PD pathogenesis. Full article
Open AccessEditor’s ChoiceReview
Hypoxia-Inducible Factors and the Regulation of Lipid Metabolism
Cells 2019, 8(3), 214; https://doi.org/10.3390/cells8030214 - 03 Mar 2019
Cited by 35
Abstract
Oxygen deprivation or hypoxia characterizes a number of serious pathological conditions and elicits a number of adaptive changes that are mainly mediated at the transcriptional level by the family of hypoxia-inducible factors (HIFs). The HIF target gene repertoire includes genes responsible for the [...] Read more.
Oxygen deprivation or hypoxia characterizes a number of serious pathological conditions and elicits a number of adaptive changes that are mainly mediated at the transcriptional level by the family of hypoxia-inducible factors (HIFs). The HIF target gene repertoire includes genes responsible for the regulation of metabolism, oxygen delivery and cell survival. Although the involvement of HIFs in the regulation of carbohydrate metabolism and the switch to anaerobic glycolysis under hypoxia is well established, their role in the control of lipid anabolism and catabolism remains still relatively obscure. Recent evidence indicates that many aspects of lipid metabolism are modified during hypoxia or in tumor cells in a HIF-dependent manner, contributing significantly to the pathogenesis and/or progression of cancer and metabolic disorders. However, direct transcriptional regulation by HIFs has been only demonstrated in relatively few cases, leaving open the exact and isoform-specific mechanisms that underlie HIF-dependency. This review summarizes the evidence for both direct and indirect roles of HIFs in the regulation of genes involved in lipid metabolism as well as the involvement of HIFs in various diseases as demonstrated by studies with transgenic animal models. Full article
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Open AccessEditor’s ChoiceReview
Revisiting Telomere Shortening in Cancer
Cells 2019, 8(2), 107; https://doi.org/10.3390/cells8020107 - 31 Jan 2019
Cited by 30
Abstract
Telomeres, the protective structures of chromosome ends are gradually shortened by each cell division, eventually leading to senescence or apoptosis. Cancer cells maintain the telomere length for unlimited growth by telomerase reactivation or a recombination-based mechanism. Recent genome-wide analyses have unveiled genetic and [...] Read more.
Telomeres, the protective structures of chromosome ends are gradually shortened by each cell division, eventually leading to senescence or apoptosis. Cancer cells maintain the telomere length for unlimited growth by telomerase reactivation or a recombination-based mechanism. Recent genome-wide analyses have unveiled genetic and epigenetic alterations of the telomere maintenance machinery in cancer. While telomerase inhibition reveals that longer telomeres are more advantageous for cell survival, cancer cells often have paradoxically shorter telomeres compared with those found in the normal tissues. In this review, we summarize the latest knowledge about telomere length alterations in cancer and revisit its rationality. Finally, we discuss the potential utility of telomere length as a prognostic biomarker. Full article
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Open AccessEditor’s ChoiceReview
Mitochondrial DNA Integrity: Role in Health and Disease
Cells 2019, 8(2), 100; https://doi.org/10.3390/cells8020100 - 29 Jan 2019
Cited by 32
Abstract
As the primary cellular location for respiration and energy production, mitochondria serve in a critical capacity to the cell. Yet, by virtue of this very function of respiration, mitochondria are subject to constant oxidative stress that can damage one of the unique features [...] Read more.
As the primary cellular location for respiration and energy production, mitochondria serve in a critical capacity to the cell. Yet, by virtue of this very function of respiration, mitochondria are subject to constant oxidative stress that can damage one of the unique features of this organelle, its distinct genome. Damage to mitochondrial DNA (mtDNA) and loss of mitochondrial genome integrity is increasingly understood to play a role in the development of both severe early-onset maladies and chronic age-related diseases. In this article, we review the processes by which mtDNA integrity is maintained, with an emphasis on the repair of oxidative DNA lesions, and the cellular consequences of diminished mitochondrial genome stability. Full article
(This article belongs to the Special Issue Mitochondrial Biology in Health and Disease)
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Open AccessEditor’s ChoiceReview
Metabolic Reprogramming in Breast Cancer and Its Therapeutic Implications
Cells 2019, 8(2), 89; https://doi.org/10.3390/cells8020089 - 26 Jan 2019
Cited by 33
Abstract
Current standard-of-care (SOC) therapy for breast cancer includes targeted therapies such as endocrine therapy for estrogen receptor-alpha (ERα) positive; anti-HER2 monoclonal antibodies for human epidermal growth factor receptor-2 (HER2)-enriched; and general chemotherapy for triple negative breast cancer (TNBC) subtypes. These therapies frequently fail [...] Read more.
Current standard-of-care (SOC) therapy for breast cancer includes targeted therapies such as endocrine therapy for estrogen receptor-alpha (ERα) positive; anti-HER2 monoclonal antibodies for human epidermal growth factor receptor-2 (HER2)-enriched; and general chemotherapy for triple negative breast cancer (TNBC) subtypes. These therapies frequently fail due to acquired or inherent resistance. Altered metabolism has been recognized as one of the major mechanisms underlying therapeutic resistance. There are several cues that dictate metabolic reprogramming that also account for the tumors’ metabolic plasticity. For metabolic therapy to be efficacious there is a need to understand the metabolic underpinnings of the different subtypes of breast cancer as well as the role the SOC treatments play in targeting the metabolic phenotype. Understanding the mechanism will allow us to identify potential therapeutic vulnerabilities. There are some very interesting questions being tackled by researchers today as they pertain to altered metabolism in breast cancer. What are the metabolic differences between the different subtypes of breast cancer? Do cancer cells have a metabolic pathway preference based on the site and stage of metastasis? How do the cell-intrinsic and -extrinsic cues dictate the metabolic phenotype? How do the nucleus and mitochondria coordinately regulate metabolism? How does sensitivity or resistance to SOC affect metabolic reprogramming and vice-versa? This review addresses these issues along with the latest updates in the field of breast cancer metabolism. Full article
(This article belongs to the Special Issue Mitochondrial Metabolic Reprogramming and Nuclear Crosstalk in Cancer)
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