Search Results (339)

Lysosomal dysfunction and endoplasmic reticulum (ER) stress play essential roles in cancer cell survival, growth, and stress adaptation. Among the various stressors in the tumor microenvironment, oxidative stress (OS) is a central driver that exacerbates both lysosomal and ER dysfunction. In healthy cells, the ER manages protein folding and redox balance, while lysosomes regulate autophagy and degradation. Cancer cells, however, are frequently exposed to elevated levels of reactive oxygen species (ROS), which disrupt protein folding in the ER and damage lysosomal membranes and enzymes, promoting dysfunction. Persistent OS activates the unfolded protein response (UPR) and contributes to lysosomal membrane permeabilization (LMP), leading to pro-survival autophagy or cell death depending on the context and on the modulation of pathways like PERK, IRE1, and ATF6. Cancer cells exploit these pathways by enhancing their tolerance to OS and shifting UPR signaling toward survival. Moreover, lysosomal impairment due to ROS accumulation compromises autophagy, resulting in the buildup of damaged organelles and further amplifying oxidative damage. This vicious cycle of ROS-induced ER stress and lysosomal dysfunction contributes to tumor progression, therapy resistance, and metabolic adaptation. Thus, targeting lysosomal and ER stress responses offers potential as cancer therapy, particularly in increasing oxidative stress and promoting apoptosis. This review explores the interconnected roles of lysosomal dysfunction, ER stress, and OS in cancer, focusing on the mechanisms driving their crosstalk and its implications for tumor progression and therapeutic resistance. Full article

Reactive oxygen species (ROS) are critical signalling molecules, but their overproduction leads to oxidative stress (OS), a common denominator in the pathogenesis of numerous non-communicable diseases (NCDs) and aging. General antioxidant therapies have largely been unsuccessful, highlighting the need for a deeper understanding of ROS amplification mechanisms to develop targeted interventions. This review proposes a unified, self-amplifying “vicious cycle” of inter-organelle crosstalk that drives pathological ROS elevation and cellular damage. We outline a pathway initiated by extracellular stressors that co-activate plasma membrane TRPM2 channels and NADPH oxidase-2. This synergy elevates cytoplasmic Ca²⁺, leading to lysosomal dysfunction and permeabilization, which in turn releases sequestered Zn²⁺. Mitochondrial uptake of this labile Zn²⁺ impairs electron transport chain function, particularly at Complex III, resulting in mitochondrial fragmentation, loss of membrane potential and a burst of mitochondrial ROS (mtROS). These mtROS diffuse to the nucleus, activating PARP-1 and generating ADPR, which further stimulates TRPM2, thereby perpetuating the cycle. This “circular domino effect” integrates signals generated across the plasma membrane (Ca²⁺), lysosomes (Zn²⁺), mitochondria (ROS) and nucleus (ADPR), leading to progressive organelle failure, cellular dysfunction, and ultimately cell death. Understanding and targeting specific nodes within this TRPM2-NOX2-Ca²⁺-Zn²⁺-mtROS-ADPR axis offers novel therapeutic avenues for NCDs by selectively disrupting pathological ROS amplification while preserving essential physiological redox signalling. Full article

NKX3-2, a transcriptional repressor factor belonging to the NK family of homeobox-containing proteins, has been widely studied for its role in promoting chondrogenic differentiation and homeostasis. NKX3-2 is upregulated in chemoresistant ovarian tumors and metastatic gastric cancer cells; however, its prognostic role and mechanistic involvement in cancer cell biology remain to be elucidated. By interrogating the TCGA database, we found that cancer patients with high NKX3-2 expression had a shorter overall survival rate than patients with low expression. In ovarian cancer patients, NKX3-2 negatively correlates with P53. Given the prominent role of the latter oncosuppressor in controlling DNA repair and cell death, here we investigate the molecular mechanism involved in this negative correlation in several ovarian cancer cell lines expressing different levels of the two proteins. We found that the high expression of endogenous or ectopic P53 reduced NKX3-2 protein expression, while its knockdown increased it. In contrast, the genetic manipulation of NKX3-2 expression did not affect P53 expression. Mechanistically, P53-mediated downregulation of NKX3-2 does not entail transcriptional activity or proteasomal clearance but occurs via P53–NKX3-2 protein–protein interaction, which in turn results in P53-induced NKX3-2 degradation via the autophagy–lysosome pathway. Remarkably, patients bearing a tumor characterized by low NKX3-2 and high MAP1LC3B expression (indicative of active autophagy) display a better prognosis. Taken together, our data indicate that NKX3-2 represents a negative prognostic factor under P53 control in ovarian cancer. From a translational point of view, identifying this novel mechanism may represent a new molecular signature capable of predicting the clinical outcome of patients, a crucial aspect of developing personalized therapeutic approaches. Full article

Dysfunction of the lysosome and autophagy–lysosome pathway is closely associated with various diseases, such as neurodegenerative diseases, non-alcoholic fatty liver disease (NAFLD), etc. Additionally, chloroquine is a clinically widely used drug for treating malaria and autoimmune diseases, but long-term or high-dose administration may lead to significant toxic side effects. Attapulgite (ATT), a natural nanomaterial with excellent adsorption capacity and biocompatibility, herein demonstrated a novel biological function in regulating the lysosomal and autophagy–lysosome pathway. ATT could be effectively internalized into lysosome-related acidic compartments. Further study revealed that ATT could restore lysosomal pH, activate cathepsin D, alleviate autophagy blockage in chloroquine-treated cells, and reduce chloroquine-elicited cell death. In a cell model related to Huntington’s disease, treatment with ATT reinforced the degradation of the mutant huntingtin proteins by increasing cathepsin D maturation and autophagy flux. ATT could also promote lipid droplet clearance in hepatocytes with palmitic acid-induced steatosis, reduce hepatic lipid accumulation, and improve fasting blood glucose in high-fat-diet-induced NAFLD mice. These findings establish ATT as a lysosomal modulator, providing a foundation for its therapeutic potential in mitigating the adverse effects associated with long-term chloroquine use, especially improving neurodegenerative and metabolic disorders. Full article

The stability of the sarcolemma is severely impaired in a series of genetic neuromuscular diseases defined as muscular dystrophies. These are characterized by the centralization of skeletal muscle syncytial nuclei, the replacement of muscle fibers with fibrotic tissue, the release of inflammatory cytokines, and the disruption of muscle protein homeostasis, ultimately leading to necrosis and loss of muscle functionality. A specific subgroup of muscular dystrophies is associated with genetic defects in components of the dystrophin–glycoprotein complex (DGC), which plays a crucial role in linking the cytosol to the skeletal muscle basement membrane. In these cases, dystrophin-associated proteins fail to correctly localize to the sarcolemma, resulting in dystrophy characterized by an uncontrolled increase in protein degradation, which can ultimately lead to cell death. In this review, we explore the role of intracellular degradative pathways—primarily the ubiquitin–proteasome and autophagy–lysosome systems—in the progression of DGC-linked muscular dystrophies. The DGC acts as a hub for numerous signaling pathways that regulate various cellular functions, including protein homeostasis. We examine whether the loss of structural stability within the DGC affects key signaling pathways that modulate protein recycling, with a particular emphasis on autophagy. Full article

Background: Tay–Sachs disease (TSD) is an autosomal recessive lysosomal storage disorder characterized by the accumulation of GM2 ganglioside due to mutations in the HEXA gene, which encodes the α-subunit of β-Hexosaminidase A. This accumulation leads to significant neuropathological effects and premature death in affected individuals. No effective treatments exist, but enzyme replacement therapies are under investigation. In our previous work, we demonstrated the internalization and efficacy of human recombinant lysosomal β-hexosaminidase A (rhHex-A), produced in the methylotrophic yeast Pichia pastoris, in reducing lipids and lysosomal mass levels in fibroblasts and neural stem cells derived from patient-induced pluripotent stem cells (iPSCs). In this study, we further evaluated the potential of rhHex-A to prevent GM2 accumulation using fibroblast and neuroglia cells from a TSD patient alongside a relevant mouse model. Methods: Fibroblasts and neuroglial cell lines derived from a murine model and TSD patients were treated with 100 nM rhHexA for 72 h. After treatment, cells were stained by anti-GM2 (targeting GM2 ganglioside; KM966) and anti-LAMP1 (lysosomal-associated membrane protein 1) colocalization staining and incubated with 50 nM LysoTracker Red DND-99 to label lysosomes. In addition, GM2AP and HEXB expression were analyzed to assess whether rhHex-A treatment affected the levels of enzymes involved in GM2 ganglioside degradation. Results: Immunofluorescence staining for LysoTracker and colocalization studies of GM2 and Lamp1 indicated reduced lysosomal mass and GM2 levels. Notably, rhHex-A treatment also affected the expression of the HEXB gene, which is involved in GM2 ganglioside metabolism, highlighting a potential regulatory interaction within the metabolic pathway. Conclusions: Here, we report that rhHex-A produced in yeast can efficiently degrade GM2 ganglioside and rescue lysosomal accumulation in TSD cells. Full article

In older adults with reduced physical performance, an increase in the labile iron pool within skeletal muscle is observed. This accumulation is associated with an altered expression of mitochondrial quality control (MQC) markers and increased mitochondrial DNA damage, supporting the hypothesis that impaired MQC contributes to muscle dysfunction during aging. The autophagy–lysosome system plays a critical role in MQC by tagging and engulfing proteins and organelles for degradation in lysosomes. The endolysosomal system is also instrumental in transferrin recycling, which, in turn, regulates cellular iron uptake. In the neuromuscular system, the autophagy–lysosome system supports the structural integrity of neuromuscular junctions, and its dysfunction contributes to muscle atrophy. While MQC was thought to protect against iron-induced cell death, the discovery of ferroptosis, a form of iron-dependent cell death, has highlighted a complex interplay between MQC and iron-inflicted damage. Ferritinophagy, the autophagic degradation of ferritin, if overactivated, can induce ferroptosis. Alternatively, aging may impair ferritinophagy, leading to ferritin accumulation and the release of toxic labile iron under stress, exacerbating oxidative damage and cellular senescence. Physical activity supports muscle health also by preserving mitochondrial quantity and quality and enhancing bioenergetics. However, therapeutic strategies for preventing or reversing physical function decline in aging are still lacking due to the insufficient understanding of the underlying mechanisms. Unveiling how disruptions in iron homeostasis impact muscle quality in older adults may allow for the development of therapeutic strategies targeting iron handling to alleviate age-associated muscle decline. Full article

Global climate change presents a significant challenge to aquatic ecosystems, with ectothermic fish being particularly sensitive to temperature fluctuations. The brain plays a crucial role in perceiving, regulating, and adapting to thermal changes, and its response to heat stress is crucial for survival. However, the molecular mechanisms underlying heat stress and acclimation in fish brains remain poorly understood. This study aimed to investigate the adaptive mechanisms of Hong Kong catfish (Clarias fuscus) brains under heat acclimation and acute heat stress using transcriptome analysis. Fish were divided into two groups: a normal temperature group (NT, 26 °C for 90 days) and a heat-acclimated group (HT, 34 °C for 90 days), followed by acute heat stress (34 °C for 72 h) and recovery (26 °C for 72 h). Heat acclimation improved C. fuscus tolerance to acute heat stress, with faster gene responses and stronger neuroprotection. Key pathways enriched included cell adhesion and ECM-receptor interactions during recovery. Apoptosis regulation was balanced, with the HT group upregulating anti-apoptotic genes to mitigate neuronal cell death. Additionally, the lysosome–phagosome pathway was activated during recovery, facilitating the transport of lysosomal enzymes and the clearance of damaged cellular components, aiding neuronal repair. Ribosome biogenesis was suppressed under heat stress to conserve energy, but this suppression was less pronounced in the HT group. In summary, heat acclimation enhances neural protection in C. fuscus brains by promoting neuronal repair, suppressing apoptosis, and activating lysosomal pathways, thereby improving tolerance to acute heat stress. These findings offer a molecular basis for breeding heat-tolerant fish species in aquaculture, and deepen our understanding of thermal adaptation in aquatic animals amid global climate change. Full article

The synergistic application of magnetic fields and iron oxide nanorod particles (IONPs) presents a novel therapeutic approach for inducing lysosome-dependent cell death (LDCL) via magneto-mechanical force (MMF). This study demonstrates the efficacy of decaying oscillating pulsed magnetic fields (DOPMFs) to propel IONPs to induce rapid tumor regression via lysosomal membrane permeabilization (LMP). The systematic evaluation of dose-dependent parameters revealed that DOPMF intensity and pulse number critically determine A375 melanoma cell viability reduction. Mechanistic investigations identified two hallmark biomarkers of LMP: increased cytosolic cathepsin B activity and downregulated LAMP-2 expression. Crucially, in vivo experiments using A375 melanoma-bearing mouse models corroborated the therapeutic potential of this approach, showing significant tumor growth inhibition without systemic toxicity or invasive procedures. Collectively, our findings demonstrate that MMF by IONPs under DOPMF stimulation exhibits significant efficacy in suppressing melanoma proliferation, offering a non-invasive, targeted approach for oncological intervention. Full article

Sphingomyelin nanoemulsions (SNs) are promising drug delivery systems with potential for treating challenging tumors, including non-small cell lung cancer (NSCLC), which has a poor prognosis and a 5-year survival rate below 5%. Understanding the toxicity mechanisms and intracellular behavior of SNs is crucial for optimizing their therapeutic application. This study aims to investigate the interaction between SNs and A549 lung adenocarcinoma cells, focusing on their cytotoxic effects and mechanisms of cellular toxicity. SNs were synthesized and characterized for size, surface charge, and stability. A549 cells were treated with varying concentrations of SNs, and cellular uptake pathways were assessed using inhibitors of energy-dependent processes. Cytotoxicity was evaluated through an alamarBlue assay to determine the IC₅₀ value after 24 h. Mechanisms of toxicity, including lysosomal and mitochondrial involvement, were examined using co-localization studies, mitochondrial membrane potential assays, and markers of apoptosis. SNs exhibited rapid cellular uptake via energy-dependent pathways. The IC₅₀ concentration for A549 cells was 0.89 ± 0.15 mg/mL, suggesting favorable cytocompatibility compared to other nanocarriers. At IC₅₀, SNs induced apoptosis characterized by lysosomal damage, mitochondrial membrane permeabilization, and the release of apoptotic factors. These effects disrupted autophagic flux and contributed to cell death, demonstrating potential for overcoming drug resistance. Resveratrol-loaded SNs showed enhanced cytotoxicity, supporting their application as targeted drug delivery vehicles. This study highlights the potential of SNs as efficient drug delivery systems for NSCLC therapy, offering insights into their cellular interactions and toxicity mechanisms. These findings pave the way for the rational design of SN-based therapeutic platforms for cancer and other mitochondria-related diseases. Full article

Objective: This review provides an overview of the current knowledge regarding the mechanisms of action of AGuIX, a clinical-stage theranostic nano-radiosensitizer composed of gadolinium. It covers the steps following the administration, from the internalization in tumor cells to the interaction with X-rays and the subsequent physical, chemical, biological, and immunological events. Results: After intravenous injection, AGuIX accumulates in tumors through the enhanced permeability and retention (EPR) effect, and its specific retention properties allow its persistence in tumors for several days. At the cellular level, the nanomedicine is internalized by endocytic processes and mainly located in the cytoplasm, especially in lysosomes. AGuIX enhances the effects of radiotherapy (RT) at several levels, starting from radiation–matter interactions to a chemical stage of reactive oxygen species (ROS) production, followed by a cascade of biological events leading to tumor cell death and immune response. Indeed, AGuIX induces a local increase in radiation dose deposition through the emission of Auger electrons, leading to a subsequent increase in ROS generation. AGuIX also impacts RT-induced biological mechanisms, including DNA damage and cell death mechanisms such as apoptosis, autophagic cell death, and ferroptosis. Last, the combination of AGuIX and RT stimulates an antitumor immune response through the induction of immunogenic cell death (ICD), the activation of dendritic and T cells, and the reprogramming of tumor-associated macrophages (TAMs) into a pro-inflammatory phenotype. Conclusions: AGuIX is a clinical-stage nanoparticle (NP) intravenously administered with pan-cancer potential due to its specific biodistribution properties and a strong ability to amplify RT-induced mechanisms. Full article

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting motor neurons. Consequent to the loss of these cells, neuromuscular functions decline, causing progressive weakness, muscle wasting, and paralysis, leading to death in 2 to 5 years. More than 90% of ALS cases are sporadic, while the remaining 10% of cases are familial, due to mutations in 40 different genes. One of the most common genes to be mutated in ALS is TARDBP (transactive response DNA binding protein 43), which encodes TDP-43 (TAR DNA-binding protein 43). A mutation in exon 6 of TARDBP causes the aminoacidic substitution G376D in the C-terminal region of TDP-43, leading to its cytoplasmic mislocalization and aggregation. In fibroblasts derived from patients carrying this mutation, we found a strong increase in lysosome number, with overexpression and higher nuclear translocation of the transcription factor TFEB. In contrast, lysosomal functionality was deeply compromised. Interestingly, lysosomal activity was unaffected at an early stage of the disease, worsening in more advanced stages. Moreover, we observed the same pathological phenotype in iPSC (induced pluripotent stem cells)-derived patient motor neurons carrying the G376D mutation. Therefore, this mutation compromises the functionality of lysosomes, possibly contributing to neurodegeneration. Full article

1′-Acetoxychavicol acetate (ACA) is a natural compound derived from rhizomes of the Zingiberaceae family that suppresses the nuclear factor κB (NF-κB) signaling pathway; however, the underlying mechanisms remain unclear. Therefore, the present study investigated the molecular mechanisms by which ACA inhibits the NF-κB signaling pathway in human lung adenocarcinoma A549 cells. The results obtained showed ACA decreased tumor necrosis factor (TNF)-α-induced intercellular adhesion molecule-1 (ICAM-1) expression in A549 cells. It also inhibited TNF-α-induced ICAM-1 mRNA expression and ICAM-1 promoter-driven and NF-κB-responsive luciferase reporter activities. Furthermore, the TNF-α-induced degradation of the inhibitor of NF-κB α protein in the NF-κB signaling pathway was suppressed by ACA. Although ACA did not affect TNF receptor 1, TNF receptor-associated death domain, or receptor-interacting protein kinase 1 protein expression, it selectively downregulated TNF receptor-associated factor 2 (TRAF2) protein expression. The proteasome inhibitor MG-132, but not inhibitors of caspases or lysosomal degradation, attenuated ACA-induced reductions in TRAF2 expression. ACA also downregulated TRAF2 protein expression in human fibrosarcoma HT-1080 cells. This is the first study to demonstrate that ACA selectively downregulates TRAF2 protein expression. Full article

The structural and functional integrity of the retinal pigment epithelium (RPE) plays a key role in the normal functioning of the visual system. RPE cells are characterized by an efficient system of photoreceptor outer segment phagocytosis, high metabolic activity, and risk of oxidative damage. RPE dysfunction is a common pathological feature in various retinal diseases. Dysregulation of RPE cell proteostasis and redox homeostasis is accompanied by increased reactive oxygen species generation during the impairment of phagocytosis, lysosomal and mitochondrial failure, and an accumulation of waste lipidic and protein aggregates. They are the inducers of RPE dysfunction and can trigger specific pathways of cell death. Autophagy serves as important mechanism in the endogenous defense system, controlling RPE homeostasis and survival under normal conditions and cellular responses under stress conditions through the degradation of intracellular components. Impairment of the autophagy process itself can result in cell death. In this review, we summarize the classical types of oxidative stress-induced autophagy in the RPE with an emphasis on autophagy mediated by molecular chaperones. Heat shock proteins, which represent hubs connecting the life supporting pathways of RPE cells, play a special role in these mechanisms. Regulation of oxidative stress-counteracting autophagy is an essential strategy for protecting the RPE against pathological damage when preventing retinal degenerative disease progression. Full article

As a structural and catalytic cofactor, copper is involved in many biological pathways and is required for the biochemistry of all living organisms. However, excess intracellular copper can induce cell death due to its potential to catalyze the generation of reactive oxygen species, thus copper homeostasis is strictly regulated. And the deficiency or accumulation of intracellular copper is connected with various pathological conditions. Since the success of platinum-based compounds in the clinical treatment of various types of neoplasias, metal-based drugs have shown encouraging perspectives for drug development. Compared to platinum, copper is an essential intracellular trace element that may have better prospects for drug development than platinum. Recently, the potential therapeutic role of copper-induced autophagy in chronic diseases such as Parkinson’s, Wilson’s, and cardiovascular disease has already been demonstrated. In brief, copper ions, numerous copper complexes, and copper-based nano-preparations could induce autophagy, a lysosome-dependent process that plays an important role in various human diseases. In this review, we not only focus on the current advances in elucidating the mechanisms of copper or copper-based compounds/preparations on the regulation of autophagy but also outline the association between copper-induced autophagy and human diseases. Full article