Mitogen-activated Protein Kinase Inhibitor Research Articles

WDR62 mediates MAPK/ERK pathway to stimulate DNA damage repair and attenuate cisplatin sensitivity in lung adenocarcinoma.

Chemotherapy resistance has long stood in the way of therapeutic advancement for lung cancer patients, the malignant tumor with the highest incidence and fatality rate in the world. Patients with lung adenocarcinoma (LUAD) now have a dismal prognosis due to the development of cisplatin (DDP) resistance, forcing them to use more costly second-line therapies. Therefore, overcoming resistance and enhancing patient outcomes can be achieved by comprehending the regulatory mechanisms of DDP resistance in LUAD. WD repeat domain 62 (WDR62) expression in LUAD tissues and in DDP-resistant or sensitive LUAD patients was analyzed bioinformatically, and a K-M plot was utilized to assess survival status. Real-time quantitative PCR was employed for WDR62 expression detection, cell-counting kit-8 assay for half maximal inhibitory concentration determination, flow cytometry for cell apoptosis detection, immunofluorescence for γ-H2AX expression analysis, and western blot for nonhomologous end joining repair and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway-related protein expression analysis. Poor prognosis was linked to WDR62, which was overexpressed in LUAD tissues and cells. Compared to sensitive cells, DDP-resistant cells had increased WDR62 expression. WDR62 knockdown may enhance DDP-induced cell apoptosis while reducing cell proliferation and DNA damage repair. Functional investigations verified that overexpressed WDR62's encouraging impact on DNA damage repair in A549/DDP cells could be reversed by MAPK inhibitors, increasing the cells' susceptibility to DDP. LUAD cells became less sensitive to DDP when WDR62 activated the MAPK/ERK pathway, which promoted DNA damage repair, indicating that DDP resistance might be reversed by treating LUAD with inhibitors of the MAPK pathway.

Luteal fibroblasts produce prostaglandins in response to IL1β in a MAPK-mediated manner

The corpus luteum is a temporary endocrine gland that is crucial for pregnancy, as it produces the progesterone needed to maintain optimal uterine conditions for implantation. In the absence of a conceptus, the corpus luteum becomes non-functional and undergoes rapid tissue remodeling to regress into a fibrotic corpus albicans. Early luteal regression is characterized by increased cytokine release. Because the role of fibroblasts in the bovine corpus luteum remains to be elucidated, the aim of this study was to elucidate the response of bovine luteal fibroblasts to inflammatory cytokines, tumor necrosis factor α (TNFα), and interleukin 1β (IL1β). Both cytokines induced canonical mitogen activated protein kinase (MAPK) signaling in luteal fibroblasts by phosphorylation of ERK1/2, p38 MAPK, and JNK. IL1β elevated expression and phosphorylation of cytosolic phospholipase A2 (cPLA2), an enzyme that mobilizes arachidonic acid for prostanoid synthesis. IL1β also elevated expression of prostaglandin-endoperoxide synthase 2 (PTGS2), another enzyme needed to synthesize prostanoids. IL1β increased PGF2α and PGE2 levels in the culture medium over 20-fold. Inhibition of MAPKs with small-molecule inhibitors abrogated the stimulatory effects of IL1β. IL1β also induced prostaglandin production in steroidogenic cells; however, there was no elevation in cPLA2. Therefore, actions of IL1β differ based on ovarian cell type. All together, we have identified luteal fibroblasts as potential inflammatory mediators during luteal regression.

PDE4D drives rewiring of the MAPK pathway in BRAF-mutated melanoma resistant to MAPK inhibitors

BackgroundPhosphodiesterase type 4D (PDE4D) breaks down cyclic AMP (cAMP) reducing the signaling of this intracellular second messenger which plays a major role in melanocyte pathophysiology. In advanced melanoma, expression of PDE4D is increased, plays a role in tumor invasion and is negatively associated with survival. In the current work, we investigated the role of PDE4D in the resistance of BRAF-mutated melanoma to mitogen-activated protein kinase (MAPK) pathway-targeted therapy.MethodsEstablished human melanoma cell line sensitive and resistant to BRAF and MEK inhibitors and tumor tissues from melanoma patients were used in this study. Immunoblotting was used to analyze protein expression and quantitative reverse transcription-PCR was used to analyze mRNA expression. DNA methylation analysis was evaluated via bisulfite treatment followed by quantitative PCR. Cell viability was measured by clonogenic assays or spheroid cultures. Cell xenograft experiments in immunodeficient mice were used to validate the results in vivo.ResultsAnalysis of baseline tumors from patients with BRAFV600E-mutated melanoma treated with MAPK inhibitors showed that higher PDE4D expression in situ predicted worse survival in patients. Furthermore, acquired resistance to BRAF and MEK inhibitors was associated with overexpression of PDE4D in situ and ex vivo. The overexpression of the PDE4D5 isoform in melanoma cells resistant to targeted therapies was explained by demethylation or deletion of a CpG island located upstream of the PDE4D5 promoter. We further showed that PDE4D overexpression allowed RAF1 activation, promoting a switch from BRAF to RAF1 isoform in BRAF-mutated melanoma, favoring resistance to BRAF and MEK inhibitors. As a result, pharmacological inhibition of PDE4 activity impeded the proliferation of resistant cells ex vivo and in vivo. The anti-tumorigenic activity of PDE4 inhibitor was achieved via inhibition of the Hippo pathway which plays an important role in resistance to targeted therapies.ConclusionsIn summary, our research showed that PDE4D drives rewiring of the MAPK pathway in BRAF-mutated melanoma resistant to MAPK inhibitors and suggests that PDE4 inhibition is a novel therapeutic option for treatment of BRAF-mutated melanoma patients.

PPARβ/δ prevents inflammation and fibrosis during diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a specific type of myocardial disease that often develops in patients suffering from diabetes, which has become the foremost cause of death among them. It is an insidious multifactorial disease caused by complex and partially unknown mechanisms that include metabolic dysregulation, local inflammation, fibrosis, and cardiomyocyte apoptosis. Despite its severity and poor prognosis, it often goes undiagnosed, and there are currently no approved specific drugs to prevent or even treat it. Peroxisome proliferator-activated receptor (PPAR)β/δ is a key metabolic regulator that has been proposed as a potential target for DCM due to its pleiotropic anti-inflammatory properties. Diabetes was induced by multiple low-dose streptozotocin (STZ) administration in wild-type and PPARβ/δ knockout male mice treated with the PPARβ/δ agonist GW0742 or vehicle. Human cardiomyocytes (AC16) and mouse atrial myocytes (HL-1) exposed to hyperglycemia and treated with PPARβ/δ agonists were also used. PPARβ/δ deletion in mice negatively impacted cardiac morphology and function, which was accompanied by interstitial fibrosis and structural remodeling of the heart. This phenotype was further exacerbated in knockout diabetic mice. At the molecular level, PPARβ/δ suppression resulted in increased expression of pro-inflammatory and pro-fibrotic markers. Some of these markers were also induced by diabetes in wild-type mice and were exacerbated in diabetic knockout mice. The activity of the transcription factors nuclear factor κB (NF-κB) and activator protein-1 (AP-1) correlated with most of these changes. Remarkably, PPARβ/δ activation partially prevented inflammation and fibrosis in the heart, as well as cardiac atrophy, induced during diabetes in mice, and also in cultured cardiomyocytes exposed to hyperglycemia. Finally, our results suggest that the beneficial effects of PPARβ/δ activation are mediated by the inhibition of mitogen-activated protein kinases (MAPK) activity and subsequent downregulation of the transcriptional activities of NF-κB and AP-1. Overall, the data suggest that PPARβ/δ agonists might be useful in preventing inflammation and fibrosis progression in DCM.

Abstract A004: RNA splicing alterations in the development of acquired MAPKi resistance in melanoma

Abstract The standard treatment for melanoma with a BRAF mutation involves Mitogen-Activated Protein Kinase inhibitors (MAPKi), which target the aberrant MAPK signaling pathway. Although patients initially respond well to this therapy, many develop acquired resistance over time. This resistance can be attributed to various altered signaling pathways, including the reactivation of the MAPK pathway, activation of alternative survival pathways like PI3K/PTEN/AKT, engagement of receptor tyrosine kinases (RTKs) such as PDGFRβ and EGFR, and developmental pathways. Despite extensive omics studies aimed at deciphering the mechanisms behind acquired resistance, the specific alterations within these pathways remain poorly understood. To gain further insights into acquired MAPKi resistance in melanoma, we explored the role of RNA splicing events by analyzing publicly available datasets of pre- and post-MAPKi treated melanoma from patient-derived cell lines and in vitro studies using PDX models. We investigated differential transcript usage (DTU) to detect specific splice variants altered during the development of resistance. Our analysis revealed significant transcript alterations during on-treatment that reverted to baseline states once resistance was established, underscoring the dynamic and adaptive nature of these changes. Genes with DTU were enriched in pathways related to MAPKi resistance, such as the MAPKi signaling pathway, PI3K/AKT pathway, and signaling by RTKs. Furthermore, the DTU-centered analysis provided better insights into MAPKi resistance mechanisms compared to standard differential gene expression (DEG) analysis, with DTUs showing higher enrichment scores in MAPKi resistance-related pathways. Further, identifying developmental splicing signatures highlights the complexity of MAPKi resistance, as it reveals significant upregulation of transcripts associated with embryonic melanoblast stem cells (MSCs) among the altered transcripts in on-treatment cell lines. This reprogramming through RNA splicing may confer an adaptive advantage, enabling melanoma cells to revert to a more plastic, stem-like state, with developmental splicing events playing a crucial role in the adaptive response to MAPKi therapy. Next, using a regulatory model based on the expression of splicing factors (SFs), we accurately predicted transcript alterations in on-treatment samples and identified key SFs. Our study highlights the crucial role of RNA splicing in the adaptive response of melanoma cells to MAPKi treatment. These insights pave the way for future research and therapeutic strategies focusing on RNA splicing to combat drug resistance in cancer. Citation Format: Sumit Mukherjee, Arashdeep Singh, Hyunjeong Joo, Sumeet Patiyal, Hyungsoo Kim, Lipika R. Pal, Kun Wang, Chi-Ping Day, Ze’ev A Ronai, Eytan Ruppin, Sridhar Hannenhalli. RNA splicing alterations in the development of acquired MAPKi resistance in melanoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr A004.

INNV-12. CUTANEOUS TOXICITIES OF MITOGEN-ACTIVATED PROTEIN KINASE INHIBITORS IN CHILDREN AND YOUNG ADULTS WITH NEUROFIBROMATOSIS-1

Abstract BACKGROUND Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder which commonly causes neoplasms leading to disfigurement or dysfunction. Mitogen-activated protein kinase inhibitors (MEKi) are generally well-tolerated treatments which target neural tumor progression in patients with NF1. Cutaneous adverse events (CAEs) are common and may hinder patients’ abilities to remain on treatment, particularly in children. We aim to characterize CAEs secondary to MEKi treatment in pediatric and young adult patients with NF1. METHODS We reviewed institutional medical records of patients under 30 years with a diagnosis of “NF1,” “NF2,” or “other neurofibromatoses” on MEKi therapy between January 1, 2019 and June 1, 2022. We recorded the time-to-onset, type, and distribution of CAEs, non-cutaneous adverse events (AEs), AE management, and tumor response. RESULTS The median age of 40 patients with NF1 was 14 years old. Tumor types included low-grade gliomas (51%) and plexiform neurofibromas (38%). MEKi used included selumetinib (69%), trametinib (25%), and mirdametinib (6%) (Table 1). A total of 74 CAEs occurred, with 28 cases of acneiform rash (38%) (Figure 1). Twenty-three out of the 28 cases of acneiform eruption were in post-pubertal patients (82.1%). Other common CAEs were paronychia, seborrheic dermatitis, eczema, xerosis, and oral mucositis. The most common treatments included oral antibiotics and topical corticosteroids. Most patients had clinical (stable or improved) tumor response (71%) while 29% had tumor progression while on a MEKi (Table 2). There was no significant association between CAE presence and tumor response (p=0.39). CONCLUSIONS MEK inhibitors have been demonstrated as a valuable treatment, but CAEs complicate the ability to stay on the treatment. Most patients in our cohort developed a CAE, demonstrating its prevalence in this population. Improvement in characterization of MEKi toxicities and their management is important to develop treatment guidelines for pediatric and young adult patients with NF1 on MEKi therapy.

Mitogen-activated protein kinase dependent presynaptic potentiation in the lateral habenula mediates depressive-like behaviors in rats.

Emerging evidence suggests that the enhanced activity of lateral habenula (LHb) is involved in depressive disorders. This abnormal potentiation of LHb neurons was shown to originate from presynaptic alterations; however, the mechanisms underlying this presynaptic enhancement and physiological consequences are yet to be elucidated. Previously, we reported that presynaptic transmission in the LHb is temporally rhythmic, showing greater activity in the afternoon than in the morning. Here, we used a learned helpless rodent model of depression to show that exposure to a stressor or incubation with the stress hormone, corticosterone, abolished the presynaptic temporal variation in the LHb. In addition, selective inhibition of mitogen-activated protein kinase (MAPK) kinase (MAPKK, MEK) activity in the LHb restored the presynaptic alteration even after stress exposure. Moreover, we observed a slight increase in phosphorylated synapsin I after stress exposure. Finally, we found that a blockade of MAPK signaling before stress exposure successfully prevented the depression-like behaviors, including behavioral despair and helplessness, in an acute learned helpless animal model of depression. Our study delineates the cellular and molecular mechanisms responsible for the abnormal presynaptic enhancement of the LHb in depression, which may mediate depressive behaviors.

Chemical genetics analysis suggests the involvement of Aurora kinase and MAPKs in aluminum-induced malate secretion in Arabidopsis.

Chemical genetics is a multidisciplinary research method. In this study, it is used to screen compounds that promote aluminum-induced malate secretion in Arabidopsis thaliana. Inhibition of p38 mitogen-activated protein kinase (p38 MAPK; LY2228820) significantly increased the transcription of Arabidopsis thaliana aluminum-activated malate transporter 1 (AtALMT1) and sensitive to proton rhizotoxicity 1 (STOP1)-regulated genes, multidrug and toxic compound extrusion and aluminum sensitive 3, but not AtSTOP1 and the Al-biomarker genes At3g28510, At5g13320, suggesting that LY2228820 increased the early expression of STOP1-regulated genes without affecting AtSTOP1 expression. Inhibition of p38 MAPK (LY2228820) and Aurora A (MLN8237) increased aluminum-activated malate transport via AtALMT1, suggesting that both MLN8237 and LY2228820 interfere with AtALMT1 activity. An increase in root elongation was also observed in Arabidopsis after applying compounds LY2228820 and MLN8237. Thus, both LY2228820 and MLN8237 may play important roles in alleviating the inhibitory effects of aluminum on roots.

Childhood Langerhans cell histiocytosis hematological involvement: severity associated with BRAFV600E loads

AbstractHematological involvement (HI) is one of the life-threatening risk organs (ROs) in Langerhans cell histiocytosis (LCH). Lahey criteria have defined HI since 1975 as hemoglobin <10 g/dL, platelets <100 G/L, leukopenia (white blood cell count <4 G/L), and/or neutrophils <1.5 G/L. Among the 2313 patients aged <18 years enrolled in the French National Histiocytosis Registry (1983-2023), 331 developed HI (median age at diagnosis, 1 year); median follow-up lasted 8.1 years. Bone marrow aspirate smears and biopsies may show reactive histiocytes, hemophagocytosis, or myelofibrosis but never confirm the diagnosis. Fifty-eight patients (17%) developed macrophage-activation syndrome, sometimes related to acute Epstein-Barr virus or cytomegalovirus infection, sometimes months before typical LCH manifestations appeared. Hemoglobin and platelet thresholds for initiating transfusion(s) appear to accurately distinguish 2 groups: mild HI (MHI; >7 g/dL and >20 G/L, respectively) and severe HI (SHI; ≤7 g/dL and ≤20 G/L). Each entity has different organ involvements, laboratory parameters, mutational status, blood BRAFV600E loads, drug sensitivities, and outcomes (MHI and SHI 10-year survival rates, 98% and 73%, respectively). Since 1998, mortality first declined with combination cladribine-cytarabine therapy and then with MAPK inhibitors since 2014. Forty-one patients (12%) developed neurodegenerative complications that have emerged as a risk for long-term survivors. These results suggest limiting the HI-RO definition to SHI, because it encompasses almost all medical complications of LCH. Future clinical trials might demonstrate that targeted therapy approaches would be better adapted for these patients, whereas MHI can be managed with classic therapies.

Kehuang capsule inhibits MAPK and AKT signaling pathways to mitigate CCl4-induced acute liver injury

Background and aimsKehuang (KH) capsule is an herbal medical product approved for the treatment of liver diseases, including liver injury, in China. However, the mechanism is still unclear. This study aimed to elucidate the protective effects of KH capsule against carbon tetrachloride (CCl4)-induced acute liver injury (ALI) in a murine model. MethodsMice were randomly divided into control, model (CCl4), CCl4+KH_Low and CCl4+KH_High group. Liver enzyme levels and histological changes were assessed to evaluate liver injury. Oxidative stress markers and inflammatory cell infiltration in liver tissues were measured. Additionally, network pharmacology was employed to explore the potential mechanisms of KH capsule. ResultsKH capsule significantly reduced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, as well as the necrotic area in liver tissue. KH capsule also decreased the infiltration of macrophages and neutrophils, thereby inhibiting the expression of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β). Furthermore, KH capsule decreased liver malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) activity. The number of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL)-positive cells in liver tissue was also reduced. The expression of nuclear factor erythroid 2 related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) proteins was significantly elevated, while the protein expression of cytochrome P450 2E1 (CYP2E1) was significantly reduced. Mass spectrometry identified genistein, galangin, wogonin, skullcapflavone II, and hispidulin as potential active ingredients of KH capsule. Network pharmacology analysis revealed enrichment in the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT) signaling pathways. Western blot analysis confirmed that KH capsule suppressed AKT, extracellular signal-regulated kinase (ERK), and p38 signaling. ConclusionsThese findings suggest that KH capsule exerts protective effects against CCl4-induced ALI, with the inhibition of MAPK and PI3K-AKT signaling pathways playing a crucial role in its mechanism of action.

Stromal reprogramming overcomes resistance to RAS-MAPK inhibition to improve pancreas cancer responses to cytotoxic and immune therapy.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy that is often resistant to therapy. An immune suppressive tumor microenvironment (TME) and oncogenic mutations in KRAS have both been implicated as drivers of resistance to therapy. Mitogen-activated protein kinase (MAPK) inhibition has not yet shown clinical efficacy, likely because of rapid acquisition of tumor-intrinsic resistance. However, the unique PDAC TME may also be a driver of resistance. We found that long-term focal adhesion kinase (FAK) inhibitor treatment led to hyperactivation of the RAS/MAPK pathway in PDAC cells in mouse models and tissues from patients with PDAC. Concomitant inhibition of both FAK (with VS-4718) and rapidly accelerated fibrosarcoma and MAPK kinase (RAF-MEK) (with avutometinib) induced tumor growth inhibition and increased survival across multiple PDAC mouse models. In the TME, cancer-associated fibroblasts (CAFs) impaired the down-regulation of MYC by RAF-MEK inhibition in PDAC cells, resulting in resistance. By contrast, FAK inhibition reprogramed CAFs to suppress the production of FGF1, which can drive resistance to RAF-MEK inhibition. The addition of chemotherapy to combined FAK and RAF-MEK inhibition led to tumor regression, a decrease in liver metastasis, and improved survival in KRAS-driven PDAC mouse models. Combination of FAK and RAF-MEK inhibition alone improved antitumor immunity and priming of T cell responses in response to chemotherapy. These findings provided the rationale for an ongoing clinical trial evaluating the efficacy of avutometinib and defactinib in combination with gemcitabine and nab-paclitaxel in patients with PDAC and may suggest further paths for combined stromal and tumor-targeting therapies.

Recurrent melanoma 25 years after initial diagnosis, presenting as metastatic disease early after heart transplantation

BackgroundCancer survivors (CS) comprise a particularly high-risk group for both de-novo and recurrent malignancies after solid organ transplantation.Case presentationWe report a case of relapsed melanoma, presented as metastatic disease seven months after heart transplantation in a patient who had an early-stage melanoma resected 25 years prior. Treatment with a combination of dabrafenib, a BRAF inhibitor, and trametinib, a mitogen-activated protein kinase (MEK) inhibitor resulted in a near-complete metabolic response, without major adverse effects.ConclusionThis case demonstrates the increased risk of recurrence in CS with melanoma, which can persist decades after cancer diagnosis. These patients may be amenable to treatment using modern treatment modalities in oncology.

Mechanistic insights on the role of Nrf-2 signalling in Huntington's disease.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder affecting individualsworldwide. It is characterized by progressive motor dysfunction, cognitive decline, and psychiatric disturbances.The pathogenesis of HD involves oxidative stress, neuroinflammation, and mitochondrial dysfunction.Nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription factor regulating cellular responses to redox imbalance and inflammation, has emerged as a potential target for therapeutic intervention. Through the use of a number of different search engines like Scopus, PubMed, Elsevier and Bentham, aliterature review was carried out with the keywords 'Huntington's Disease, 'Pathology of HD' and 'Nrf2 signallingpathway'.Using the keywords that were given above, this review was carried out in order to collect the most recent publications and gain an understanding of the breadth of the extensive research that has been conducted on the role of Nrf2 in HD pathogenesis. Oxidative stress and neuroinflammation significantly contribute to HD progression. Activation of Nrf2 offers neuroprotection by enhancing anti-oxidant defense mechanisms.Furthermore, several signaling pathways, play crucial roles in HD pathophysiology.Pharmacological modulation of these pathways through selective inhibitors or agonists shows promise for the development of new therapeutic strategies. The various downstream pathways such as extracellular signal-related kinase (ERK), phosphoinositide3-Kinase (PI3-K), 5'-AMP-activated protein kinase (AMPK), Sirtuins, Mitogen-activated protein kinases (MAPK) plays a role in alleviating pathophysiology of HD.Diverse reports of these studies demonstrated PI3-K/AMPK/ERK/Sirtuins activators and MAPK inhibitors as encouraging targets in alleviating HD pathophysiology.

Trehalose Attenuates In Vitro Neurotoxicity of 6-Hydroxydopamine by Reducing Oxidative Stress and Activation of MAPK/AMPK Signaling Pathways.

The effects of trehalose, an autophagy-inducing disaccharide with neuroprotective properties, on the neurotoxicity of parkinsonian mimetics 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenylpiridinium (MPP+) are poorly understood. In our study, trehalose suppressed 6-OHDA-induced caspase-3/PARP1 cleavage (detected by immunoblotting), apoptotic DNA fragmentation/phosphatidylserine externalization, oxidative stress, mitochondrial depolarization (flow cytometry), and mitochondrial damage (electron microscopy) in SH-SY5Y neuroblastoma cells. The protection was not mediated by autophagy, autophagic receptor p62, or antioxidant enzymes superoxide dismutase and catalase. Trehalose suppressed 6-OHDA-induced activation of c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and AMP-activated protein kinase (AMPK), as revealed by immunoblotting. Pharmacological/genetic inhibition of JNK, p38 MAPK, or AMPK mimicked the trehalose-mediated cytoprotection. Trehalose did not affect the extracellular signal-regulated kinase (ERK) and mechanistic target of rapamycin complex 1 (mTORC1)/4EBP1 pathways, while it reduced the prosurvival mTORC2/AKT signaling. Finally, trehalose enhanced oxidative stress, mitochondrial damage, and apoptosis without decreasing JNK, p38 MAPK, AMPK, or AKT activation in SH-SY5Y cells exposed to MPP+. In conclusion, trehalose protects SH-SY5Y cells from 6-OHDA-induced oxidative stress, mitochondrial damage, and apoptosis through autophagy/p62-independent inhibition of JNK, p38 MAPK, and AMPK. The opposite effects of trehalose on the neurotoxicity of 6-OHDA and MPP+ suggest caution in its potential development as a neuroprotective agent.

Elevated serum GDF15 level as an early indicator of proximal tubular cell injury in acute kidney injury

Acute kidney injury (AKI) is a high-burden medical condition, and current diagnostic criteria can only assess AKI after full manifestation. Stress marker growth differentiation factor 15 (GDF15) was reported to have a role in kidney injury of critical patients. Herein, we evaluated dynamic changes in GDF15 across diverse AKI scenarios and explored the underlying mechanisms of its induction. Serum parameters and renal lesions were analyzed in mouse models of unilateral ischemia-reperfusion injury (uni-IRI) and unilateral ureteral obstruction (UUO). The human proximal tubular (HK−2) cell line was stimulated with various conditions, and induction of GDF15 expression was determined. Serum GDF15 levels were rapidly induced within hours after injury in both animal models and declined thereafter. Renal GDF15 expression exhibited a temporary and early increased induction and was mainly located in aquaporin 1-positive proximal tubules in both unilateral AKI model tissues. In cell experiments, rapid GDF15 production was highly induced by t-BHP and CoCl2. Treatment with either an antioxidant or mitogen-activated protein kinase inhibitors abolished t-BHP- and CoCl2-mediated GDF15 expression. In addition, silencing nuclear factor erythroid 2-related factor 2 expression also reduced the basal and t-BHP- or CoCl2-mediated GDF15 expression level in HK-2 cells. Our data showed that elevated serum GDF15 levels could be detected early in unilateral AKI models without notable alterations in kidney function parameters. GDF15 expression was associated with oxidative stress- and hypoxia-mediated proximal tubular cell injury. These data document that elevated serum GDF15 can possibly serve as an early biomarker for proximal tubular cell injury in AKI.

Sinapine suppresses ROS-induced C2C12 myoblast cell death through MAPK and autophagy pathways.

Oxidative stress in skeletal muscle can lead to muscle atrophy through reactive oxygen species (ROS)-induced damage and cell death. tert-Butyl hydroperoxide (TBHP), an exogenous ROS generator, induces oxidative stress and cell death in various cells. Sinapine from cruciferous plants possesses beneficial effects, but its role in protecting skeletal muscle cells against ROS-induced cell death remains unclear. This study demonstrates that sinapine pretreatment significantly reduced TBHP-induced cell death and ROS accumulation in a dose-dependent manner. TBHP activated mitogen-activated protein kinase (MAPK) pathways including Akt, p38, and JNK, and triggered autophagy. Sinapine suppressed the phosphorylation of Akt, MEK3/6, p38, MEK4, and JNK, and modulated key autophagy markers. Notably, the co-treatment of MAPK inhibitors attenuated TBHP-induced cell death and LC3B-II accumulation. These findings suggest that sinapine is a promising phytochemical for mitigating oxidative stress-mediated muscle injury, offering potential therapeutic strategies for maintaining skeletal muscle homeostasis and addressing muscle-related pathologies.

Clarithromycin Modulates Neutrophilic Inflammation Induced by Prevotella intermedia in Human Airway Epithelial Cells.

Objectives: In the present study, we aimed to clarify the mechanisms by which periodontal pathogens, particularly Prevotella intermedia, induce severe neutrophilic inflammation. In addition, we aimed to test the efficacy of macrolides, which has not been resolved in the neutrophilic inflammation induced by P. intermedia. Methods: NCl-H292 human airway epithelial cells were pre-incubated with clarithromycin for 2 h before incubation with P. intermedia supernatants. Then, C-X-C motif chemokine ligand 8 (CXCL8) transcription and interleukin (IL)-8 production were measured. To elucidate the signaling pathway, mitogen-activated protein kinase inhibitors were added to the cell culture, and the cells were subjected to Western blotting. Results:P. intermedia supernatants promoted CXCL8 transcription and IL-8 production, and the reactions were significantly suppressed by clarithromycin pretreatment. Only trametinib, the selective mitogen-activated extracellular signal-regulated kinase inhibitor, downregulated CXCL8 transcription and IL-8 production. Furthermore, Western blotting revealed that stimulation with P. intermedia supernatants specifically induces extracellular signal-regulated kinases (ERK) 1/2 phosphorylation, which is suppressed by clarithromycin pretreatment. Notably, the interference analysis revealed that ERK3 might be dispensable for IL-8 production under the stimulation of P. intermedia supernatants. Conclusions: Our results provide new insight into the mechanism underlying P. intermedia-induced production of IL-8 from human airway epithelial cells. Furthermore, macrolides might have therapeutic potential in regulating periodontal pathogen-induced neutrophilic inflammation in the lungs.

P38α Mitogen-Activated Protein Kinase-An Emerging Drug Target for the Treatment of Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disorder, characterized by the formation of amyloid β and tau protein aggregates in the brain, neuroinflammation, impaired cholinergic neurotransmission, and oxidative stress, resulting in the gradual loss of neurons and neuronal function, which leads to cognitive and memory deficits in AD patients. Chronic neuroinflammation plays a particularly important role in the progression of AD since the excessive release of proinflammatory cytokines from glial cells (microglia and astrocytes) induces neuronal damage, which subsequently causes microglial activation, thus facilitating further neurodegenerative changes. Mitogen-activated protein kinase (MAPK) p38α is one of the key enzymes involved in the control of innate immune response. The increased activation of the p38α MAPK pathway, observed in AD, has been for a long time associated not only with the maintenance of excessive inflammatory process but is also linked with pathophysiological hallmarks of this disease, and therefore is currently considered an attractive drug target for novel AD therapeutics. This review aims to summarize the current state of knowledge about the involvement of p38α MAPK in different aspects of AD pathophysiology and also provides insight into the possible therapeutic effects of novel p38α MAPK inhibitors, which are currently studied as potential drug candidates for AD treatment.

Mu-Opioid Receptor (MOR) Dependence of Pain in Chemotherapy-Induced Peripheral Neuropathy.

We recently demonstrated that transient attenuation of Toll-like receptor 4 (TLR4) in dorsal root ganglion (DRG) neurons, can both prevent and reverse pain associated with chemotherapy-induced peripheral neuropathy (CIPN), a severe side effect of cancer chemotherapy, for which treatment options are limited. Given the reduced efficacy of opioid analgesics to treat neuropathic, compared with inflammatory pain, the cross talk between nociceptor TLR4 and mu-opioid receptors (MORs), and that MOR and TLR4 agonists induce hyperalgesic priming (priming), which also occurs in CIPN, we determined, using male rats, whether (1) antisense knockdown of nociceptor MOR attenuates CIPN, (2) and attenuates the priming associated with CIPN, and (3) CIPN also produces opioid-induced hyperalgesia (OIH). We found that intrathecal MOR antisense prevents and reverses hyperalgesia induced by oxaliplatin and paclitaxel, two common clinical chemotherapy agents. Oxaliplatin-induced priming was also markedly attenuated by MOR antisense. Additionally, intradermal morphine, at a dose that does not affect nociceptive threshold in controls, exacerbates mechanical hyperalgesia (OIH) in rats with CIPN, suggesting the presence of OIH. This OIH associated with CIPN is inhibited by interventions that reverse Type II priming [the combination of an inhibitor of Src and mitogen-activated protein kinase (MAPK)], an MOR antagonist, as well as a TLR4 antagonist. Our findings support a role of nociceptor MOR in oxaliplatin-induced pain and priming. We propose that priming and OIH are central to the symptom burden in CIPN, contributing to its chronicity and the limited efficacy of opioid analgesics to treat neuropathic pain.

Downregulation of nuclear receptor-binding SET domain protein 1 induces proinflammatory cytokine expression via mitogen-activated protein kinase pathways in U87MG cells

Haploinsufficiency of the nuclear receptor binding SET domain-containing protein 1 gene (NSD1) leads to a neurodevelopmental disorder known as Sotos syndrome (SOTOS). This study investigated the effects of NSD1 knockdown in glial cells. U87MG glioma cells were transfected with siRNA targeting NSD1, which resulted in morphological changes characteristic of activated astrocytes. These activated phenotypes were accompanied by specific activation of mitogen-activated protein kinase (MAPK) signaling pathways, particularly those mediated by p38 MAPK and c-Jun N-terminal kinase (JNK). Transcriptome analysis showed increased expression of proinflammatory cytokine genes, particularly interleukin (IL)-1α, IL-1β, and IL-6, following NSD1 knockdown. Treatment with MAPK inhibitors significantly reduced the cytokine induction caused by NSD1 knockdown, with the p38 MAPK inhibitor being more effective than the JNK inhibitor. These findings provide new insights into the role of NSD1 loss in neurological dysfunctions associated with SOTOS.