Search Results (691)

Accumulating data indicate a role for the dysregulation of the cell cycle, autophagy and apoptosis in diabetic kidney disease. We aimed to evaluate the mediators of the PI3K/Akt and MAPK/ERK signaling pathways in the kidney of db/db mice, a model of type 2 diabetes, treated by the SGLT2 inhibitor empagliflozin, the DPP4 inhibitor linagliptin, and metformin. Eight-week-old male db/db mice were randomly assigned to treatment by these agents or vehicle for 8 weeks. Age-matched db/+ mice acted as controls. AMPKα1 and PI3Kp110β were evaluated in the renal cortex and medulla by Western Blot. Phosphorylated forms of principal molecules involved in the PI3K/Akt and MAPK/ERK pathways were assessed by multiplex analysis. Db/db mice had decreased PI3Kp110β, increased phospho-PTEN, HSP27 and MEK1 in the renal cortex and medulla, BAD in the renal cortex and decreased phospho-rpS6 in the renal medulla. Empagliflozin prevented the changes in the levels of cortical PI3Kp110β, phospho-MEK1, and medullar phospho-PTEN. Linagliptin restored PI3Kp110β levels. Both agents further decreased medullar phospho-rpS6. Metformin upregulated cortical AMPKα1, medullar PI3Kp110β, phospho-GSK-3α/β and MEK1, and increased phospho-HSP27 in the renal cortex and medulla. The data may provide further explanation of the mechanism underlying the development of diabetic kidney disease, as well as the renal protective effect of anti-diabetic agents. Full article

Obesity is a major metabolic disorder characterized by excessive lipid accumulation and adipocyte differentiation. The mitogen-activated protein kinase kinase 5 (MEK5) signaling pathway has been implicated in diverse cellular processes; however, its role in adipogenesis remains incompletely understood. In this study, we investigated the anti-adipogenic effects of BIX02189, a selective MEK5 inhibitor, using 3T3-L1 adipocytes, human adipose-derived stem cells (hASCs), and zebrafish models. Treatment with BIX02189 significantly reduced lipid accumulation and triglyceride content during adipocyte differentiation in a dose-dependent manner without marked cytotoxicity. BIX02189 effectively suppressed MEK5 phosphorylation and downregulated the expression of key adipogenic transcription factors, including peroxisome proliferator-activated receptor gamma (PPAR-γ) and CCAAT/enhancer-binding protein alpha (C/EBP-α). In addition, BIX02189 decreased the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and STAT5, as well as the expression of lipogenic markers such as fatty acid synthase (FAS), perilipin A, and leptin. Conversely, BIX02189 enhanced AMP-activated protein kinase (AMPK) phosphorylation and markedly reduced the protein and mRNA expression of acetyl-CoA carboxylase (ACC), a key enzyme involved in fatty acid synthesis. Similar anti-adipogenic effects were observed in hASCs. Furthermore, BIX02189 significantly attenuated lipid accumulation in a zebrafish obesity model without affecting body length or causing overt toxicity. Collectively, these findings demonstrate that pharmacological inhibition of MEK5 suppresses adipogenesis and lipid accumulation through regulation of the STAT3/STAT5–PPAR-γ axis and activation of AMPK signaling. These findings provide the first evidence that MEK5 inhibition exerts anti-adipogenic effects in adipocytes and zebrafish, highlighting the MEK5 signaling pathway as a previously unrecognized regulator of adipogenesis and lipid metabolism. Full article

Melanoma is an aggressive skin cancer that has the potential to metastasize to the lymph nodes, lungs, liver, and brain. Therefore, the prevention and treatment of this condition are essential for achieving lower incidence rates and improving patient outcomes. Traditional treatment methods like surgery, radiation therapy, and chemotherapy have shown limited efficacy in the treatment of metastatic melanoma, and hence new treatment strategies have been developed. These recently developed treatment options include combining targeted therapies with immunotherapies to reduce drug resistance and improve overall effectiveness in preventing melanoma progression. Moreover, BRAF mutations are found in approximately 40–50% of cutaneous melanomas, and NRAS mutations in 15–25%, making these the two most common oncogenic drivers in the MAPK pathway. While alterations in other genes such as KRAS (~1.7%), HRAS (~1%), and MET (~2–4%) are relatively rare in melanoma, they still remain important to disease biology and are under investigation as potential therapeutic targets. These alterations may contribute to tumor progression, metastasis, and therapeutic resistance, highlighting the importance of continued investigation of targeted strategies in melanoma. This review aims to explore the role of each of these genes in melanoma, discusses their resistance mechanism, and summarizes preclinical and clinical trials involving drug combinations. By integrating current evidence on melanoma-associated genomic alterations with available targeted and immune approaches, this review aims to define molecular and clinical contexts that suggest potential treatment selections for melanoma patients. Full article

Resistance to combined BRAF and MEK inhibition remains a major barrier to durable disease control in BRAF-mutant melanoma. Acyclic retinoid (ACR; peretinoin) is a clinically studied retinoid, but its activity in MAPK inhibitor-resistant melanoma remains incompletely defined. Here, we established A375P-derived dabrafenib plus trametinib-resistant clones and evaluated ACR mainly in the A375PDTR-D clone as an in vitro proof-of-concept model. Resistant clones retained higher viability and failed to suppress ERK phosphorylation under dabrafenib plus trametinib treatment. In A375PDTR-D cells, ACR reduced short-term viability and clonogenic growth and was associated with decreased STAT3 Tyr705 phosphorylation, reduced EGFR, Cyclin D1, and Cyclin B1 expression, and increased p27KIP1. ACR did not detectably suppress AKT, MEK/ERK, or basal JNK phosphorylation under the tested conditions. These findings support further investigation of ACR as a candidate non-MAPK adjunct strategy; however, generalizability to broader melanoma models, formal drug-interaction status, direct cell-cycle/apoptosis effects, clinically achievable exposure, and in vivo efficacy remain to be established. Full article

Background/Objectives: Cabozantinib is a tyrosine kinase inhibitor that primarily targets MET. It has become an important drug in the treatment of renal cell carcinoma (RCC); however, many patients do not respond to cabozantinib treatment and there is no effective next-line therapy. In this study, we identified molecular-targeted drugs that exhibit synergistic effects with cabozantinib using CRISPR/Cas9 screening. Methods: A kinome-wide synthetic lethal CRISPR/Cas9 screen was used to identify target molecules using 786-o RCC cells. A library was generated, and treatment with vehicle or cabozantinib was carried out, followed by next-generation sequencing to identify candidate genes. A combination index based on the Chou–Talalay method was used to evaluate the synergistic effect of cabozantinib through cell viability assays. Xenograft assays were conducted to determine the effect in vivo. Results: CRISPR/Cas9-based screening revealed four genes (MEK1, DCLK1, DYRK3, and FGFR1) that were candidates for synthetic lethality by cabozantinib in RCC cells. We focused on MEK1 because the MEK1 inhibitor cobimetinib has been approved for melanoma treatment. In a cell proliferation assay using 786-o and A498 RCC cells, the combination of cobimetinib and cabozantinib exhibited a synergistic effect. A xenograft assay also revealed a significant synergistic effect of cobimetinib and cabozantinib. Conclusions: CRISPR/Cas9 screening identified MEK1 as a candidate for a synthetic lethal target with cabozantinib in RCC. The combined inhibition of MET/VEGFR and MEK1 suppressed compensatory MAPK reactivation and downregulated the PI3K-Akt pathway, including the survival-associated genes PPP2R3B and ATF6B, and produced significant tumor growth suppression in vivo. These findings highlight the potential of cabozantinib plus cobimetinib, an already-FDA-approved MEK inhibitor, as a readily translatable combination strategy to overcome cabozantinib resistance in RCC. Full article

Background: Treatment options are limited, and outcomes remain poor for patients with metastatic uveal melanoma (MUM). We conducted an investigator-initiated, prospective, single-arm, single-institution, phase II study evaluating the combination of an FAK inhibitor (defactinib) with a RAF/MEK inhibitor (avutometinib) for the treatment of MUM. Methods: From February 2021 through January 2023, 12 patients with MUM were treated with the combination of defactinib and avutometinib. Defactinib was given 200 mg twice daily, and avutometinib was given 3.2 mg twice a week. Both drugs were given for 3 weeks on and 1 week off (28-day cycle). Disease control rate was the primary endpoint of this study. Results: Median lines of prior therapies for the patients were two. After two cycles, six patients achieved stable disease while six patients developed progressive disease (disease control rate of 50%). With a median follow-up of 20.0 months, the median progression-free survival was 3.0 months and the median overall survival was 20.0 months. The combination was quite tolerable for patients, with no patients requiring dose reduction or discontinuation. Trial enrollment was stopped early by study sponsors before the anticipated accrual of 18 patients due to no patients having a significant reduction in disease. Conclusions: This is the first study reporting on the use of an FAK inhibitor combination in MUM. Further research should seek to elucidate an optimal combination treatment strategy for MUM, such as FAK and PKC inhibitors, for improved blockade of the signaling pathways downstream of GNAQ/GNA11 driver mutations. Full article

Selective inhibition of MEK isoforms remains a central challenge in MAPK-targeted drug discovery, largely due to the structural similarity between MEK1 and MEK2. While MEK1 has been extensively characterized, the structural basis of MEK2-specific ligand recognition is not fully understood. Here, we present crystal structures of human MEK2 in complex with the noncompetitive inhibitor U0126 and the allosteric inhibitor refametinib at resolutions of 3.15 Å and 3.30 Å, respectively. Despite a conserved kinase fold, MEK2 exhibits isoform-specific features within the N-lobe β-sheet. Additional differences are observed in the relative orientation of the helix C and activation segment, and the helix F-supported regulatory spine. Structural differences are reflected in micromolar binding affinities for U0126 (K_d = 9.8 μM) and refametinib (K_d = 7.4 μM). Notably, a single N-lobe substitution (Thr87 in MEK2 versus Phe83 in MEK1) selectively enhanced U0126 binding. The MEK2 T87F mutant exhibited an approximately twofold increase in affinity, while refametinib binding remained largely unchanged. SEC–MALS analysis demonstrated that MEK2 predominantly exists as a monomer in solution, contrasting with the reported homodimeric behavior of MEK1. Molecular dynamics simulations supported these findings by revealing isoform-specific differences in oligomeric state-dependent flexibility and inhibitor-induced dynamics. Collectively, our findings define the structural basis underlying the differential inhibitor recognition of MEK2 and MEK1, providing mechanistic insight into isoform-selective MEK-targeted drug design. Full article

Thyroid cancer (TC) is the most common endocrine malignancy, with incidence increasing worldwide. Although most differentiated TCs have a favorable prognosis, radioiodine (RAI)-refractory differentiated thyroid cancer (DTC), BRAF inhibitor-resistant papillary thyroid cancer, and anaplastic thyroid cancer (ATC) remain major areas of unmet clinical need. The sirtuin (SIRT) family of NAD⁺-dependent enzymes has emerged as a multifaceted regulator of TC biology, with isoform-specific dichotomous roles: SIRT1, SIRT6, and SIRT7 act as tumor promoters through engagement of BRAF/MAPK, PI3K/AKT, epithelial–mesenchymal transition (EMT), and Hippo pathways, while SIRT3 and SIRT4 function as tumor suppressors via mitochondrial metabolic regulation. This review synthesizes recent developments that expand the therapeutic landscape: (i) the recognition that SIRT7 functions as a desuccinylase with preclinically identified oncogenic substrates, modifying KIF23 in ATC and LATS1 in PTC; (ii) the emerging roles of isoform-specific SIRT axes, including the NAMPT–SIRT1–PD-L1 axis, SIRT6-associated regulatory T-cell biology, and SIRT2 as a T-cell metabolic checkpoint, as determinants of immune microenvironment state and potential modulators of immune checkpoint inhibitor response; and (iii) the SIRT6–nuclear receptor coactivator 4 (NCOA4) ferritinophagy axis as a supported ferroptosis vulnerability in ATC, with potential but still hypothesis-generating relevance to dedifferentiated and RAI-refractory DTC. Importantly, the therapeutic logic for SIRT6 is disease-state-specific rather than contradictory: SIRT6 inhibition is rationalized in BRAF-driven aggressive PTC and DTC contexts where SIRT6 supports MAPK signaling, EMT, and ferroptosis resistance, whereas in SIRT6-high ATC, the same enzyme’s NCOA4-dependent ferritinophagy activity may instead be exploited to enhance ferroptosis sensitivity. We review the current SIRT modulator pharmacological toolkit—including EX-527, OSS_128167, and emerging SIRT7-selective inhibitors—and identify the substantial clinical translation gap, with no SIRT-targeted clinical trial yet conducted in TC, despite strong preclinical rationale. We outline biomarker-stratified combination strategies with BRAF/MEK inhibitors, multikinase inhibitors, immune checkpoint inhibitors, and ferroptosis inducers, prioritizing biomarker-driven preclinical validation and, where supported by efficacy and safety data, subsequent early-phase evaluation in BRAF V600E-mutant and SIRT6-high thyroid cancer. Sirtuins thus represent a mechanistically promising and potentially biomarker-stratifiable therapeutic hypothesis for difficult-to-treat thyroid cancer; however, clinical translation remains at an early stage and requires validated biomarkers, isoform-selective compounds, and disease-specific in vivo evidence. Full article

Patients with BRAF^V600E-mutated metastatic lung cancer benefit from both BRAF plus MEK inhibitors and immune checkpoint inhibitor (ICI)–chemotherapy. This study evaluated the cost-effectiveness of first-line ICI–chemotherapy compared with BRAF plus MEK inhibitors in these patients. This economic analysis, with a 15-year time horizon and an annual 3% discount, was conducted from the perspective of the healthcare sectors in Taiwan and the US. Simulated patients were entered into partitioned survival models upon initiation of first-line therapies. The model inputs were derived from the FRONT-BRAF study (progression-free/overall survival, adverse events, and subsequent therapies), insurance payments or retail prices (costs of drugs, physician visits, monitoring, adverse events, and end-of-life care), and a hospital cohort (health utility). Deterministic and probabilistic analyses were performed. The incremental cost-effectiveness ratios (ICERs) of ICI–chemotherapy compared with BRAF plus MEK inhibitors (Taiwan: $73,561/QALY; US: $290,279/QALY) exceeded the willingness-to-pay (WTP) thresholds (Taiwan: $70,000/QALY; US: $150,000/QALY). The drug costs of subsequent therapies and the utility values of the progressive-disease state were the major determinants of ICERs. In Taiwan, ICI–chemotherapy had a 41.0% probability of being cost-effective at the WTP threshold. ICI–chemotherapy had a higher probability of being cost-effective than BRAF plus MEK inhibitors when the WTP exceeded $300,000/QALY in the US. Our analysis suggests that, despite the longer survival of first-line ICI–chemotherapy compared with BRAF plus MEK inhibitors, ICI–chemotherapy is not a cost-effective strategy for patients with BRAF^V600E-mutated metastatic lung cancer. Full article

Cutaneous Melanoma is a biologically heterogeneous malignancy. Although recent therapeutic advances have improved survival, durable remissions remain elusive for many patients. Surgical excision with stage-appropriate margins and selective nodal staging remains the cornerstone of curative-intent management. In contrast, conventional cytotoxic chemotherapy now plays a limited, largely palliative role given its modest efficacy and substantial toxicity. Targeted therapy with BRAF/MEK inhibitors has improved outcomes in patients with BRAF V600-mutant melanoma, resulting in rapid tumor regression and meaningful survival benefits. However, long-term disease control is frequently compromised by adaptive resistance, commonly driven by MAPK pathway reactivation or compensatory PI3K/AKT signaling. In parallel, immune checkpoint inhibitors targeting PD-1, CTLA-4, and emerging pathways have reshaped treatment across disease stages, enabling deep and sometimes durable responses. Despite this progress, primary and acquired resistance, as well as acute and chronic immune-related toxicities, continue to pose significant clinical challenges. Current therapeutic strategies focus on rational combinations of targeted therapy, checkpoint blockade, IL-2-based approaches, oncolytic viruses, and adoptive cell therapies such as tumor-infiltrating lymphocytes to enhance response depth and durability. However, these intensified regimens carry increased toxicity risks, highlighting the need for improved patient selection and monitoring. Overall, emerging evidence supports a paradigm shift toward optimized treatment sequencing, response-adapted surgical strategies, and biomarker-guided personalization to maximize clinical benefit while minimizing toxicity. Full article

Toll-like receptors (TLRs) are essential components of the innate immune system that enable host cells to sense microbial and endogenous danger signals and to initiate inflammatory and antimicrobial responses. Activation of TLRs triggers complex intracellular signaling networks that culminate in the induction of pro-inflammatory cytokines, type I interferons, and co-stimulatory molecules. In addition to the well-characterized nuclear factor κB (NF-κB) and interferon regulatory factor (IRF) pathways, mitogen-activated protein kinases (MAPKs) play a critical modulatory role in TLR signaling. MAPK/ERK kinase (MEK) inhibitors were originally developed for the treatment of cancer and are widely used in clinical oncology. Accumulating evidence indicates that pharmacological inhibition of MEK/extracellular signal regulated kinase (ERK) signaling profoundly affects immune cell function and TLR-driven responses. Depending on timing, dose, and disease context, MEK inhibition can attenuate excessive inflammation but may also interfere with protective host defense mechanisms. This duality highlights the context-dependent role of MEK/ERK signaling in infection and inflammation. In this review, I summarize current knowledge on the integration of MEK/ERK signaling into TLR-mediated innate immune responses and discuss the immunological consequences of MEK inhibition in infectious and inflammatory settings. By synthesizing mechanistic and translational studies, I aim to provide a framework for understanding MEK inhibitors as immune modulators rather than as broadly acting anti-inflammatory agents. Full article

Primary pulmonary adenocarcinoma in dogs is rare, and effective systemic therapies remain limited. To evaluate the molecular basis of potential precision oncology approaches, hotspot mutations in HER2, BRAF, KRAS, and PIK3CA were analyzed in 20 surgically resected canine pulmonary adenocarcinomas and three canine pulmonary adenocarcinoma cell lines. HER2 V659E and BRAF V595E mutations were each detected in 3/20 cases (15%), while KRAS G12V was detected in 1/20 cases (5%). No PIK3CA hotspot mutations were identified. The BRAF V595E mutation was additionally detected in the AZACL2 cell line. Functional analysis demonstrated increased sensitivity of AZACL2 cells to the BRAF inhibitor dabrafenib and MEK inhibitors including trametinib, compared with BRAF wild-type cell lines. These findings support MAPK pathway dependency in BRAF-mutant canine pulmonary adenocarcinoma. The mutation spectrum was broadly consistent with previous reports, suggesting a conserved molecular landscape across geographic regions. Collectively, these data identify BRAF and HER2 alterations as clinically relevant candidates for molecular diagnostics and targeted therapy in canine pulmonary adenocarcinoma. Full article

Oxidative stress is a major contributor to the development of age-related macular degeneration (AMD), and excessive oxidative stress can induce retinal pigment epithelium (RPE) dysfunction, apoptosis, and retinal degeneration. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) is a major enzymatic source of reactive oxygen species (ROS); however, its mechanistic role in sodium iodate (NaIO₃)-induced oxidative injury remains unclear. Tetrahydrocurcumin (THC), the major metabolite of curcumin, exhibits potent antioxidant and cytoprotective activities, but its protective effects against AMD-associated retinal degeneration have not been fully elucidated. In the present study, we investigated whether THC protects against NaIO₃-induced ROS-mediated apoptosis in RPE cells through regulation of NOX2 signaling. In vitro, THC significantly attenuated NaIO₃-induced cytotoxicity and prevented apoptosis by suppressing hydrogen peroxide (H₂O₂) production and intracellular ROS accumulation in ARPE-19 cells. THC also preserved mitochondrial membrane potential by inhibiting the Src/p47^phox/NOX2 signaling pathway and subsequently attenuated mitochondria-mediated apoptotic signaling. Furthermore, THC markedly reduced the expression of apoptotic proteins, including Bax, cleaved caspase-3, and cleaved PARP, concomitantly with suppression of Ras/Raf/MEK/ERK signaling. Mechanistically, treatment with the selective NOX2 inhibitor GSK2795039 significantly attenuated NaIO₃-induced ROS accumulation and mitochondrial depolarization, while co-treatment with THC further enhanced these protective effects. In vivo, THC ameliorated NaIO₃-induced retinal structural abnormalities by preserving the outer nuclear layer (ONL), reducing caspase-3 expression, and improving pupillary light responses in mice. Collectively, these findings demonstrate that THC protects against NaIO₃-induced retinal degeneration through suppressing NOX2-dependent oxidative stress and downstream Ras/Raf/MEK/ERK-mediated apoptotic signaling, highlighting its potential as a therapeutic candidate for AMD and other oxidative stress-related retinal disorders. Full article

Objectives: To describe the scientific evidence regarding adjuvant treatment for stage III and IV cutaneous melanoma and the unresolved issues in this setting. Methods: This review examines the main studies on adjuvant medical therapies approved over the years by the Food and Drug Administration and European Medicines Agency together with the main evidence related to the treatments referred to in the National Comprehensive Cancer Network and European Society of Clinical Oncology guidelines at the time of submission (May 2026) for stage III and IV cutaneous melanoma. A particular focus on immunotherapy (interferon, ipilimumab, and anti-PD-1 antibodies, both as monotherapy and in combination) and targeted therapy with anti-BRAF agents, either as monotherapy or in combination with MEK inhibitors, is given. Besides that, this work also evaluates the role of radiation therapy and addresses some unresolved issues, such as adjuvant therapy in stage IIIA and treatment selection in BRAF-mutated melanoma. Results: Adjuvant therapy for stage III and IV cutaneous melanoma has evolved over the years, starting with interferon and progressing to the use of immunocheckpoint inhibitors and targeted therapy. However, not all treatments that have proven effective in metastatic disease have subsequently played a role in the adjuvant setting. Conclusions: Currently, adjuvant treatment for stage III and IV cutaneous melanoma involves the use of anti-PD-1 antibodies (nivolumab and pembrolizumab) and dabrafenib plus trametinib if the patient has a BRAF V600 mutation. It was not possible to identify the adjuvant therapy of choice for BRAF-mutated melanoma, and several factors must be considered when deciding between immunotherapy and targeted therapy. The role of radiation therapy remains controversial and could be discussed by the multidisciplinary team as part of the adjuvant strategy in selected patients. Likewise, adjuvant therapy for stage IIIA melanoma should be carefully evaluated in light of the risk–benefit ratio. Full article

Multidrug resistance (MDR) is defined as resistance to apparently unrelated drugs with different mechanisms of action, a phenomenon that seriously decreases the efficacy of many anticancer therapeutic regimens. MDR is mainly associated with a high expression of ATP-binding cassette (ABC) transporters, including ABCB1, ABCG2, and members of the ABCC subfamily, which actively extrude many anticancer drugs of various classes out of the cells. Protein kinase inhibitors (PKIs) were developed as therapies targeting oncogenic kinases but later appeared to be both substrates and inhibitors of ABC transporters and thus can potentially reverse MDR. This comprehensive review evaluates how PKIs regulate ABC transporters through three key mechanisms: altering expression, modifying subcellular localization, and inhibiting the efflux function. We evaluated the effect of PKIs that target tyrosine and serine/threonine kinases, such as EGFR/ErbB, JAK, VEGFR, BCR-Abl, ALK, FGFR, MEK1/2, B-RAF, BTK, CDK4/6, MET, RET, PDGFR and SYK. We have collected both computational studies and experimental reports, including functional assays, mechanistic studies of inhibition, and structural approaches that have evaluated PKIs’ effects on ABC transporters. We conclude that although PKIs can be ABC substrates, they mainly inhibit drug efflux, with minimal and context-dependent effects on transporter expression or localization. Full article