Search Results (216)

The mitogen-activated protein kinase (MAPK) signaling cascade is fundamental in regulating cellular proliferation and differentiation, cell survival and cell death via apoptosis. Disruption of the MAPK signaling cascade at any point can lead to the evasion of apoptosis and unchecked cell growth and proliferation, leading to oncogenesis. This narrative review describes MAPK pathway dysregulation, its therapeutic targets, and resistance mechanisms. The therapeutic targeting of the MAPK pathway is complex due to the dual context-dependent roles of several kinases in the signaling cascade. Despite the therapeutic effectiveness of MAPK inhibitors, cancer cells develop chemoresistance that needs to be targeted via bypassing (c-Jun N-terminal kinases) JNK, protein kinase AKT and (mammalian target of rapamycin) mTOR signaling cascades, pairing MAPK inhibitors with multiple immune agents and targeting the MAPK pathway downstream of (extracellular signal-regulated kinase) ERK to prevent its reactivation mechanisms using combination therapies, downstream signaling regulators and (Proteolysis Targeting Chimeras) PROTACs. Additionally, MAPK-mediated regulation of ferroptosis is a novel oncological therapeutic targeting strategy for controlling tumor progression. The inhibition of the RAF/MAPK pathway results in alteration of several key regulators of ferroptosis, including SLCA11, GSH, GPX4 and NCO4A, hence affecting lipid cellular iron concentration and lipid peroxidation. Emerging therapies targeting the MAPK pathway should be designed considering crosstalk, compensatory signaling mechanism activation, the role of ferroptosis and the impact of the tumor microenvironment. Full article

Neuroblastoma (NB) is the most prevalent paediatric extracranial solid tumour, which remains a major therapeutic challenge, especially in cases of recurrent and disseminated disease. c-Jun N-terminal kinases (JNKs) are increasingly evidenced to play a key role in NB tumourigenesis and progression through apoptosis regulation, making selective JNK inhibitors promising candidates for use in targeted anticancer drugs in NB. Our study comprehensively investigated the acute antineoplastic potential of the selective JNK inhibitor AS601245 (JNK inhibitor V) on the human MYCN-non-amplified neuroblastoma cell line, SH-SY5Y, with particular focus on its effects on NB cell viability, proliferation, migration, apoptosis, gene and protein expression, and mitochondrial metabolism. JNK V selectively impaired NB cell survival and function, without exerting cytotoxicity toward normal human Schwann cells (HSC) and fibroblasts (BJ). Our findings highlighted a dose-dependent inhibition of proliferation (XTT assay), colony formation (clonogenic assay), and migration (wound healing assay), accompanied by increased caspase-3 activity (caspase-3 assay), pro-apoptotic genes (qRT-PCR) and protein (Western blotting) expression, and significant disruption of both oxidative phosphorylation and glycolysis (Agilent Seahorse XF Assay). These results provide new insights into the therapeutic potential of JNK inhibition as a targeted strategy for NB. Full article

Perlecan, a major heparan sulfate proteoglycan in the vascular basement membrane, plays an essential role in maintaining endothelial barrier integrity, regulating fibroblast growth factor-2 signaling, and exerting anticoagulant activity. Although alterations in perlecan expression are implicated in the initiation and progression of atherosclerosis, the upstream regulatory mechanisms remain unclear. In this study, we investigated the effects of extracellular ATP on perlecan expression in vascular endothelial cells. ATP, but not ADP or adenosine, suppressed perlecan expression at both mRNA and protein levels in a time- and concentration-dependent manner. This suppression was recovered by knockdown of P2Y2 receptor (P2Y2R), but not by P2X4 receptor, P2X7 receptor, or P2Y1 receptor knockdown, indicating the selective involvement of P2Y2R. Mechanistically, ATP reduced Akt phosphorylation mediated by P2Y2R, and inhibition of Akt by inhibitors decreased perlecan expression, whereas inhibitors of phosphoinositide 3-kinase, mammalian target of rapamycin complex 1, extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, c-Jun N-terminal kinases did not exhibit this recovery effect. These results suggest that ATP downregulates perlecan synthesis via the P2Y2R-mediated inhibition of Akt signaling. Given that ATP is markedly elevated under pathological conditions, such as inflammation and platelet activation, suppression of perlecan synthesis is an important mechanism by which ATP promotes vascular disease progression. Full article

c-Jun N-terminal kinase (JNK) activation has been shown to play a crucial role in the development of various types of cancer. IQ-1S is a JNK inhibitor based on the 11H-indeno[1,2-b]quinoxalin-11-one scaffold. The aim of this study was to investigate the antiproliferative effect of IQ-1S on MCF7 breast cancer cells in both two-dimensional (2D) monolayer and 3D multicellular spheroid test-systems. Non-adherent, non-tethered 3D objects were generated from single MCF7 breast cancer cells in a hydrogel array. IQ-1S was added directly to the cells seeded in the hydrogel array. MCF7 spheroids were grown for 7 days. Spheroid size, growth rate, and morphology were assessed at single-object resolution. The study revealed significant differences in the size, morphology and some vital characteristics of breast cancer 3D objects when treated with the JNK inhibitor compared to vehicle (dimethyl sulfoxide)-treated controls. Spheroids treated with IQ-1S (20 μM) after 7 days are significantly smaller than the control objects. This difference was not attributable to variations in the initial number of cells seeding for the spheroid formation. Morphological examinations showed that 3D multicellular objects grown from IQ-1S-treated cells lose their regular, round morphology, in contrast to control spheroids. Furthermore, cell proliferation measured using a label-free impedance monitoring platform was reduced in monolayer (2D) culture of MCF7 cells in the presence of 10 and 20 μM IQ-1S. MCF7 cells in 2D culture treated with IQ-1S (20 μM) for 72 and 153 h showed a significant increase in apoptosis as assessed by flow cytometry with annexin V/propidium iodide staining. An in silico evaluation showed that compound IQ-1S has generally satisfactory ADME (absorption, distribution, metabolism, and excretion) properties and high bioavailability. We conclude that IQ-1S effectively inhibits the growth of 3D spheroids and MCF7 cells in 2D culture and has a high potential for use in preclinical tumor growth models. Full article

Microcirculation in cutaneous tissue is essential to balance oxygen delivery and maintain the health of the skin. Senescence contributes to microcirculatory dysfunction through mechanisms involving chronic inflammation, structural remodeling of microvessels, and disturbances in hemodynamics. In this study we investigated the promoting effect of escin on blood flow through topical application. To elucidate the molecular mechanisms of escin, kinase phosphorylation changes in human umbilical vein endothelial cells (HUVECs) were examined. Escin stimulates the Wnt/β-Catenin and c-Jun N-terminal kinase (JNK) signaling pathway in cultured HUVECs. To clarify the target of escin in the Wnt/β-Catenin signaling pathway, gene expression in response to escin treatment was evaluated, and escin-mediated signaling activation was accompanied by glycogen synthase kinase-3 beta (Gsk3β), according to inhibitor studies performed with IWR1 (tankyrase inhibitor). In addition, the expression level of the Gsk3β were down-regulated by escin treatment in cultured HUEVCs. Escin also enhanced vascular remodeling, and, when applied topically, led to a sustained increase in cutaneous blood flow. Escin-mediated Wnt signaling activation could enhance blood vessel networks via Gsk3β down-regulation. In conclusion, our data demonstrate that escin promotes angiogenic behavior and enhances adenosine-induced perfusion in humans, thereby supporting its potential role in modulating cutaneous microcirculation. Full article

Increased drug metabolism and elimination are prominent mechanisms mediating multidrug resistance (MDR) to not only chemotherapy drugs but also anti-cancer natural products, such as benzyl isothiocyanate (BITC). To evaluate the possibility of combined utilization of a certain compound to overcome this resistance, we focused on glutathione S-transferase (GST)-dependent metabolism of BITC. The pharmacological treatment of a pi-class GST-selective inhibitor, 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX), significantly increased BITC-induced toxicity in human colorectal cancer HCT-116 cells. However, NBDHEX unexpectedly increased the level of the BITC–glutathione (GSH) conjugate as well as BITC-modified proteins, suggesting that NBDHEX might increase BITC-modified protein accumulation by inhibiting BITC–GSH excretion instead of inhibiting GST. Furthermore, NBDHEX significantly potentiated BITC-induced apoptosis with the enhanced activation of apoptosis-related pathways, such as c-Jun N-terminal kinase and caspase-3 pathways. These results suggested that combination treatment with NBDHEX may be an effective way to overcome MDR with drug efflux and thus induce the biological activity of BITC at lower doses. Full article

Breast cancer is the second most common cancer in the United States and consists of 30% of all new female cancer each year. PKC iota (PKC-$\iota$) is a bonafide human oncogene and is overexpressed in many types of cancer, including breast cancer. This study explores the role of PKC-$\iota$ in regulating the transcription factor Jun proto-oncogene (c-Jun), pro-inflammatory cytokine Tumor Necrosis Factor-alpha (TNF-$\alpha$), and the Mitogen-Activated Protein Kinase/Jun N-terminal kinase (MAPK/JNK) pathway, which also exhibits an oncogenic role in breast cancer. ICA-1S, a PKC-$\iota$ specific inhibitor, was used to inhibit PKC-$\iota$ to observe the subsequent effect on the levels of c-Jun, TNF-$\alpha$, and the MAPK/JNK signaling pathway. To obtain the results, cell proliferation assay, Western blotting, co-immunoprecipitation, small interfering RNA (siRNA), immunofluorescence, flow cytometry, cycloheximide (CHX) chase assay, and reverse transcription quantitative PCR (RT-qPCR) techniques were implemented. ICA-1S significantly inhibited cell proliferation and induced apoptosis in both breast cancer cell lines. Treatment with ICA-1S and siRNA also reduced the expression levels of the MAPK/JNK pathway protein, c-Jun, and TNF-$\alpha$ in both cell lines. PKC-$\iota$ was also found to be strongly associated with c-Jun, via which it regulated the MAPK/JNK pathway. Additionally, ICA-1S was found to promote the degradation of c-Jun and decrease the mRNA levels of c-Jun. We concluded that PKC-$\iota$ plays a crucial role in regulating breast cancer, and the inhibition of PKC-$\iota$ by ICA-1S reduces breast cancer cell proliferation and induces apoptosis. Therefore, targeting PKC-$\iota$ as a potential therapeutic target in breast cancer could be a significant approach in breast cancer research. Full article

Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment worldwide. AMD development is associated with inflammation, oxidative stress, and a progressive proteostasis imbalance, in whose regulation, c-Jun N-terminal kinases (JNKs) play a crucial role. JNK inhibition is being discussed as a new way to prevent and treat AMD, but there are no data on JNK signaling in the retina and its changes with age and with AMD development. Here, for the first time, we assessed JNK-signaling activity in the retina and did not detect its age-related changes in healthy Wistar rats. By contrast, manifestation and progression of the AMD-like pathology in OXYS rats occurred simultaneously with JNK pathway activation. We also confirmed that selective JNK3 inhibitor 11H-indeno[1,2-b]quinoxalin-11-one oxime sodium salt (IQ-1S) can suppress neurodegenerative changes in the OXYS rat retina. Its effects were prevention of the destructive changes in retinal synapses and the suppression of the JNK signaling pathway activity during active progression of AMD signs in OXYS rats. Full article

Biological, physiological, and psychological stressors cause a “stress response” in our bodies. Stressors that are sensorily perceived (either acute or chronic) trigger hormonal responses from the sympathetic nervous system—the SAM and HPA axis—that effect intended organs to alert the individual. Other stressors have a direct effect on the target organ(s) of the body—e.g., physical injury and wounds, toxins, ionizing, and UV radiation. Both kinds of stressors change cell equilibrium, often leading to reactive oxygen species (ROS) accumulation and cellular damage. Among the signaling pathways involved in fighting these stressors, the c-Jun-N-terminal kinases (JNK) respond to diverse kinds of stressors. This review focuses on JNK1 and JNK2, both of which are ubiquitously present in all cell types, and attention is paid to gastrointestinal tract epithelial cells and their response—including tight junction disruption and cytoskeletal changes. We discuss the seemingly opposite roles of JNK1 and JNK2 in helping cells choose pro-survival and pro-apoptotic pathways. We examine the common features of the JNK protein structure and the possibilities of discovering JNK-isoform-specific inhibitors since, although JNK1 and JNK2 are involved in multiple diseases, including cancer, obesity, diabetes, musculoskeletal and liver disease, no cell-specific or isoform-specific inhibitors are available. Full article

Disruption of the blood–brain barrier (BBB) accompanies many brain diseases, including stroke, neurodegenerative diseases, and brain tumors, leading to swelling, increased neuroinflammation, and neuronal death. In recent years, it has become clear that the c-Jun N-terminal kinase (JNK) signaling pathway is involved in disruption of the structural integrity of the BBB. Activation of the JNK signaling pathway has a negative effect on the functioning of the cellular elements of the neurovascular unit that form the BBB. The aim of this review is to assess the role of the JNK signaling pathway in the disruption of the structural integrity of the BBB in animal models of stroke (MCAO/R, middle cerebral artery occlusion with reperfusion), Alzheimer’s disease, and brain tumors and to analyze the effects of compounds of various natures that directly or indirectly affect the activity of the JNK signaling pathway. These compounds can reduce damage to the BBB and brain edema, reduce neuroinflammation and oxidative stress, reduce the expression of proapoptotic factors, and increase the expression of tight junction proteins. Certain compounds mitigate BBB dysfunction, being promising candidates for neuroprotective therapies. These agents exert their effects, in part, through inhibition of the c-Jun N-terminal kinase (JNK) signaling pathway, a mechanism linked to reduced neuronal damage and improved BBB integrity. Full article

(1) Background: Silicosis, a chronic lung fibrosis disorder triggered by the accumulation of silica dust in the deep lung regions, is characterized by intricate molecular mechanisms. Among these, the NOX2 (NADPH oxidase 2) and JNK (C-Jun N-terminal kinase) signaling pathways play pivotal roles in the progression of pulmonary fibrosis. Despite their significance, the precise mechanisms underlying the crosstalk between these pathways remain largely unexplored. (2) Methods: To unravel these interactions, we examined the interplay between JNK and NOX2 in human epithelial cells subjected to silica dust exposure through in vivo assays, followed by validation using single-cell sequencing. Our findings consistently revealed elevated expression levels of key components from both the JNK signaling pathway and NOX2 in the lungs of silicosis-induced mice and silica-treated human epithelial cells. (3) Results: Notably, the activation of these pathways was linked to increased ROS (reactive oxygen species) production, elevated levels of profibrogenic factors, and diminished cell proliferation in silica-exposed human lung epithelial cells. Further mechanistic analyses demonstrated that JNK signaling amplifies NOX2 expression and ROS production induced by silica exposure, while treatment with the JNK inhibitor SP600125 mitigates these effects. Conversely, overexpression of NOX2 enhanced silica-induced JNK activation and the expression of epithelial–mesenchymal transition (EMT)-related factors, whereas NOX2 knockdown exerted the opposite effect. These results suggest a positive feedback loop between JNK and NOX2 signaling, which may drive EMT in lung epithelial cells following silica exposure. (4) Conclusions: This reciprocal interaction appears to play a critical role in lung epithelial cell damage and the pathogenesis of silicosis, shedding light on the molecular mechanisms underlying profibrogenic disease and offering potential avenues for therapeutic intervention. Full article

The role of the mitogen-activated protein kinase (MAPK) pathway in choroidal neovascularization (CNV) remains unclear. This study investigates the involvement of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 pathways in CNV development, as well as the therapeutic potential of sprouty 2 (SPRY2), an MAPK inhibitor, in a laser-induced mouse model. The expressions of ERK, JNK, and p38 proteins were analyzed using Western blotting and immunostaining. Immunofluorescence imaging revealed increased p-ERK and p-JNK expression in the retina, retinal pigment epithelium (RPE), and choroid up to day 7. Co-immunostaining showed p-ERK colocalized with CD31, CD11b, F4/80, cytokeratin, and GFAP in the retina, while p-JNK and p-p38 were associated with angiogenesis and inflammation throughout the retina and choroid. Compared to aflibercept, SPRY2 administration significantly inhibited CNV lesions, endothelial proliferation, fibrosis, and apoptosis, while better-preserving RPE integrity. SPRY2-treated mice showed a stronger reduction in CNV-related inflammation, epithelial–mesenchymal transition, and photoreceptor apoptosis. These results highlight the MAPK pathway’s role in CNV pathogenesis, with ERK primarily mediating Müller cell gliosis and JNK, contributing to angiogenesis and inflammation. SPRY2 effectively suppressed CNV lesions, supporting its potential as a therapeutic target for CNV treatment via MAPK pathway modulation. Full article

Colorectal cancer remains a significant cause of mortality worldwide. A spiro-acridine derivative, (E)-1′-((4-bromobenzylidene)amino)-5′-oxo-1′,5′-dihydro-10H-spiro[acridine-9,2′-pyrrole]-4′-carbonitrile (AMTAC-19), showed significant cytotoxicity in HCT-116 colorectal carcinoma cells (half maximal inhibitory concentration, IC50 = 10.35 ± 1.66 µM) and antioxidant effects after 48 h of treatment. In this study, Molegro Virtual Docker v.6.0.1 software was used to investigate the interactions between AMTAC-19 and the Extracellular Signal-Regulated Kinase 1 (ERK1), c-Jun N-terminal Kinase 1 (JNK1), and p38 Mitogen-Activated Protein Kinase α (p38α MAPK). In vitro assays were conducted in HCT-116 cells to evaluate the effect of AMTAC-19 on the modulation of these proteins’ activities using flow cytometry. Furthermore, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in the presence or absence of ERK1/2, JNK, and p38 MAPK inhibitors was used to evaluate the involvement of these enzymes in AMTAC-19 cytotoxicity. ROS production was assessed using the 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) assay at various incubation times (30 min, 1 h, 6 h, 12 h, and 24 h), and the MTT assay using N-acetyl-L-cysteine (NAC) was performed. In silico results indicated that AMTAC-19 interacts with ERK1, JNK1, and p38α MAPK. Additionally, AMTAC-19 activated ERK1/2 and JNK1 in HCT-116 cells, and its cytotoxicity was significantly reduced in the presence of ERK1/2 and JNK inhibitors. AMTAC-19 also induced a significant increase in ROS production (30 min and 1 h), while NAC pretreatment reduced its cytotoxicity. These findings support AMTAC-19′s in vitro antitumor effect through ROS-dependent activation of ERK and JNK pathways. Full article

Background/Objectives: The ribosomal S6 kinase 2 (S6K2) acts downstream of the mechanistic target of rapamycin complex 1 and is a homolog of S6K1 but little is known about its downstream effectors. The objective of this study was to use an unbiased transcriptome profiling to uncover how S6K2 promotes breast cancer cell survival. Methods: RNA-Seq analysis was performed to identify novel S6K2 targets. Cells were transfected with siRNAs or plasmids containing genes of interest. Western blot analyses were performed to quantify total and phosphorylated proteins. Apoptosis was monitored by treating cells with different concentrations of doxorubicin. Results: Silencing of S6K2, but not S6K1, decreased p21 in MCF-7 and T47D breast cancer cells. Knockdown of Akt1 but not Akt2 decreased p21 in MCF-7 cells whereas both Akt1 and Akt2 knockdown attenuated p21 in T47D cells. While Akt1 overexpression enhanced p21 and partially reversed the effect of S6K2 deficiency on p21 downregulation in MCF-7 cells, it had little effect in T47D cells. S6K2 knockdown increased JUN mRNA and knockdown of cJun enhanced p21. Low concentrations of doxorubicin increased, and high concentrations decreased p21 levels in T47D cells. Silencing of S6K2 or p21 sensitized T47D cells to doxorubicin via c-Jun N-terminal kinase (JNK)-mediated downregulation of Mcl-1. Conclusions: S6K2 knockdown enhanced doxorubicin-induced apoptosis by downregulating the cell cycle inhibitor p21 and the anti-apoptotic protein Mcl-1 via Akt and/or JNK. Full article

Inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), in intestinal epithelial cells significantly contribute to inflammatory bowel disease (IBD) and colorectal cancer (CRC). Given our previous findings that TNF-α is upregulated in intestinal epithelial Caco-2 cells induced by skatole, a tryptophan-derived gut microbiota metabolite, the present study aimed to explore the relationship between skatole and IL-6, alongside TNF-α. Skatole elevated the promoter activity of IL-6 as well as TNF-α, and increased IL-6 mRNA expression and protein secretion. In addition to activating NF-κB, the NF-κB inhibitor BAY 11-7082 reduced skatole-induced cell survival and the mRNA expression of IL-6 and TNF-α. NF-κB activation was attenuated by the extracellular signal-regulated kinase (ERK) pathway inhibitor U0126 and the p38 inhibitor SB203580, but not by the c-Jun N-terminal kinase (JNK) inhibitor SP600125. U126 and SB203580 also decreased the skatole-induced increase in IL-6 expression. When skatole-induced AhR activation was inhibited by CH223191, in addition to promoting NF-κB activation, IL-6 expression was enhanced in a manner similar to that previously reported for TNF-α. Taken together, these results suggest that skatole-elicited NF-κB activation induces IL-6 and TNF-α expression, although AhR activation partially suppresses this process. The ability of skatole to increase the expression of IL-6 and TNF-α may significantly affect the development and progression of these diseases. Moreover, the balance between NF-κB and AhR activation appears to govern the skatole-induced increases in IL-6 and TNF-α expression. Therefore, the present findings provide new insights into the mechanisms linking tryptophan-derived gut microbiota metabolites with colorectal disease. Full article