Search Results (116)

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

Dihydrosanguinarine (DHSA) is a naturally occurring benzo[c]phenanthridine alkaloid primarily isolated from plants of the Papaveraceae family. DHSA exhibits broad pharmacological activities, including antitumor, anti-inflammatory, hypoglycemic, neuroprotective, analgesic, anxiolytic, antiarrhythmic, and antimicrobial effects. Mechanistically, DHSA regulates multiple signaling pathways and molecular targets, including TMEM16A, p53, Ras/Raf/MEK/ERK, PI3K/AKT, NF-κB, PPARγ, GABA_A receptors, and voltage-gated sodium channels. Compared with its biosynthetic precursor sanguinarine (SA), DHSA exhibits a comparatively favorable safety profile while retaining considerable biological activity. Pharmacokinetic studies further suggest that DHSA possesses acceptable membrane permeability, gastrointestinal absorption potential, enterohepatic circulation characteristics, and sustained systemic exposure. In addition, structure–activity relationship (SAR) and electrostatic surface potential (ESP) analyses indicate that the chemically accessible C6 position may provide opportunities for rational structural optimization. Nevertheless, the clinical translation of DHSA still faces several challenges. Therefore, this review systematically summarizes the physicochemical properties, pharmacological activities, molecular mechanisms, SAR characteristics, ESP distribution, toxicity, pharmacokinetic behavior, and clinical prospects of DHSA, aiming to provide a theoretical basis for its future drug development and translational application. Full article

Postnatal loss of cardiac regenerative capacity coincides with profound remodeling of signaling, structural, and metabolic programs in the developing heart. Here, we profiled Insulin growth factor (IGF)/Fibrobrast growth factor (FGF)/insulin receptors (InsR), Ras/Raf/MEK/ERK pathway components, cytoskeletal markers, and cell-cycle/metabolic proteins in mouse whole-heart tissue at P3, P7, P14, P28, and adulthood. IGF-1R- and IGF-2R-associated signals declined sharply during maturation, whereas InsR changed more modestly. FGFR1-derived immunoreactive species showed a transient early postnatal increase before marked reduction at later stages. These receptor-associated changes paralleled strong decreases in B-Raf, MEK1, and MEK2, together with pronounced loss of MEK1/2 activation-loop phosphorylation. MEK1 Thr292 phosphorylation also declined markedly, identifying a previously unrecognized developmental phosphorylation pattern. Structural maturation was accompanied by stable Actn2 expression, downregulation of immature cytoskeletal markers, increased cytochrome c and myoglobin, and significant loss of Aurora B and phospho-histone H3 in adult hearts. Together, these findings describe a coordinated postnatal maturation program in which signaling, cytoskeletal remodeling, metabolism, and proliferative withdrawal change in parallel. These data are consistent with reduced MAPK pathway activity during maturation and highlighting this signaling as node associated with closure of the neonatal regenerative window. Full article

Targeted therapies are reshaping oncology by enabling treatment selection based on actionable molecular alterations, improving precision, and reducing unnecessary toxicity. This review provides an up-to-date overview of current targeted treatment modalities and the medicinal chemistry principles that support their discovery and optimization. We synthesize evidence on small-molecule and biologic strategies spanning receptor and non-receptor kinases and their major signaling axes (PI3K-AKT-mTOR and RAS-RAF-MEK-ERK), apoptosis regulation (BCL-2 family), DNA repair via poly(ADP-ribose) polymerase (PARP) inhibition, and epigenetic or metabolic targets including histone deacetylases (HDACs), bromodomain and extra-terminal proteins (BET), and mutant isocitrate dehydrogenases (IDH1/2). Across these areas, we summarize recurrent resistance mechanisms and the rationale for combination or sequential approaches. Biologic targeted therapy is discussed in parallel, including immune checkpoint blockade, antibody–drug conjugates, bispecific antibodies (BsAb), and cell therapies such as chimeric antigen receptor T cells, with emphasis on biomarker-guided patient stratification. Finally, we outline emerging directions beyond canonical nodes, including modulation of the p53-MDM2/MDM4 axis, ferroptosis control through AIFM2/FSP1, and innate immune pathways such as CD47-SIRPa and the stimulator of interferon genes (STING). Overall, the field is shifting from single-target inhibition toward integrated strategies that combine precise molecular targeting with an understanding of signaling network dynamics, resistance evolution, and therapeutic vulnerabilities. Full article

Loss of epithelial polarity is a critical driver of tumor progression; however, how core polarity regulators interface with oncogenic signaling pathways in hepatocellular carcinoma (HCC) remains incompletely defined. LLGL scribble cell polarity complex component 1 (LLGL1) is an evolutionarily conserved polarity protein with well-established tumor-suppressive roles in multiple epithelial malignancies. Nevertheless, how LLGL1 loss shapes oncogenic signaling outputs and cellular phenotypes in HCC remains unclear. In this study, we investigated the consequences of LLGL1 knockout (KO) in epithelial-like Huh-7 HCC cells. LLGL1 loss resulted in enhanced proliferative capacity and increased clonogenic potential, accompanied by altered cell-cycle distribution characterized by reduced G1-phase and increased S-phase fractions (p < 0.001). At the signaling level, LLGL1 KO cells displayed potentiated EGFR-driven RAS/MAPK pathway activation, with increased EGFR phosphorylation, enhanced downstream RAF1–MEK–ERK–RSK signaling, elevated EGFR abundance, and selective modulation of RAF1 protein levels. Functionally, LLGL1 loss markedly enhanced migratory and invasive behavior (p < 0.0001). Despite increased motility, LLGL1 KO cells exhibited remodeling of epithelial–mesenchymal transition (EMT)-associated markers without evidence of a classical EMT program. Collectively, these findings position LLGL1 loss as a central factor associated with altered MAPK signaling, EMT marker remodeling, and tumor-promoting cellular phenotypes in HCC. Full article

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality, underscoring the need to elucidate molecular mechanisms that regulate tumor cell state and behavior. Leucine zipper–like post-translational regulator 1 (LZTR1) regulates RAS/mitogen-activated protein kinase (MAPK) signaling, yet LZTR1-dependent transcriptional alterations in HCC cells remain poorly defined. To address this gap and determine how LZTR1 loss reshapes signaling, transcriptional programs, and cellular phenotypes, we established a LZTR1 knockout (KO) Hep3B model and combined pathway profiling with transcriptomic and functional analyses. Immunoblotting revealed increased phosphorylation across the RAF–MEK–ERK–RSK cascade in LZTR1 KO cells. Transcriptome-wide RNA sequencing (RNA-Seq) identified differentially expressed genes, and selected findings were validated by qRT-PCR. Gene set enrichment analysis indicated that the epithelial–mesenchymal transition (EMT) gene set was enriched in control cells. At the protein level, LZTR1 loss remodeled EMT-associated markers in a hybrid epithelial–mesenchymal pattern consistent with epithelial–mesenchymal plasticity (EMP). Vimentin was suppressed at transcript and protein levels. Functionally, LZTR1 KO cells exhibited impaired wound closure and reduced transwell migration and invasion. Collectively, these findings define an EMP-related molecular and phenotypic state associated with LZTR1 deficiency in Hep3B cells, providing insight into how LZTR1 loss reshapes tumor cell behavior in HCC. Full article

Background: Pheochromocytomas (PCCs) and paragangliomas (PGLs), collectively known as PPGLs, are rare neuroendocrine tumors that produce catecholamines. The majority of PPGL cases are caused by germline and/or somatic mutations in over 20 different genes. A study of post-surgical PCC patients revealed a high risk of new tumor recurrence in both hereditary and apparently sporadic cases, suggesting that some germline mutations remain undetected. Since transcript levels can indicate gene dysfunction, our study focuses on the transcriptional profiling of PCC-associated genes in post-surgical patients. Methods: RT-PCR was performed on blood samples from patients and a control group. The t-SNE algorithm was applied to the transcriptional data. Sanger sequencing was used to identify mutations in the coding sequences of the VHL, SDHB, RET, and NF1 genes. Results: We obtained transcriptional profiles for 11 genes involved in the Krebs cycle and for 21 genes involved in the hypoxia, PI3K/AKT/mTOR, and RAS/RAF/ERK signaling pathways. We identified a minimal set of 16 genes with stable transcription levels that can be used to differentiate PCC patients from controls. Germline mutations in the VHL, SDHB, RET and NF1 genes, which correlated with an altered transcriptional profile, were detected in three patients. Conclusions: Our pilot data suggest that transcript levels of the genes involved in Krebs cycle, hypoxia, PI3K/AKT/mTOR, and RAS/RAF/ERK signaling pathways indicate their potential suitability as a candidate diagnostic marker. The results from this pilot study form the basis for a larger project to investigate gene transcription in an expanded cohort of patients who have undergone surgery for PCC. Full article

Background: Colorectal cancer (CRC) demonstrates substantial clinical and biological diversity across age groups, ancestral backgrounds, and treatment settings, alongside a rising incidence of early-onset disease (EOCRC). The mitogen-activated protein kinase (MAPK) pathway is a major driver of CRC development and therapy response; however, the distribution and prognostic value of MAPK alterations across distinct patient subgroups remain unclear. Methods: We analyzed 2515 CRC tumors with harmonized demographic, clinical, genomic, and treatment metadata. Patients were stratified by ancestry (Hispanic/Latino [H/L] vs. non-Hispanic White [NHW]), age at diagnosis (early-onset [EO] vs. late-onset [LO]), and FOLFOX chemotherapy exposure. MAPK pathway alterations were identified using a curated gene set encompassing canonical EGFR-RAS-RAF-MEK-ERK signaling components and regulatory nodes. Conversational artificial intelligence (AI-HOPE and AI-HOPE-MAPK) enabled natural language-driven cohort construction and exploratory analytics; findings were validated using Fisher’s exact testing, chi-square analyses, and Kaplan–Meier survival estimates. Results: MAPK pathway disruption demonstrated marked heterogeneity across ancestry and treatment contexts. Among EO H/L patients, FGFR3, NF1, and RPS6KA6 mutations were significantly enriched in tumors not receiving FOLFOX, whereas PDGFRB alterations were more frequent in FOLFOX-treated EO H/L tumors relative to EO NHW counterparts. In late-onset H/L disease, NTRK2 and PDGFRB mutations were more common in non-FOLFOX tumors. Distinct MAPK-associated alterations were also observed among NHW patients, particularly in non-FOLFOX settings, including AKT3, FGF4, RRAS2, CRKL, DUSP4, JUN, MAPK1, RRAS, and SOS1. Survival analyses provided borderline evidence that MAPK alterations may be linked to improved overall survival in treated EO NHW patients. Conversational AI markedly accelerated analytic throughput and multi-parameter discovery. Conclusions: Although MAPK alterations are pervasive in CRC, their distribution varies meaningfully by ancestry, age, and treatment exposure. These findings highlight NF1, MAPK3, RPS6KA4, and PDGFRB as potential biomarkers in EOCRC and H/L patients, supporting the need for ancestry-aware precision oncology approaches. Full article

Central nervous system (CNS) tumors consist of a diverse set of malignancies that remain clinically challenging due to their biological complexity, high morbidity, and limited responsiveness to current therapies. A growing body of genomic evidence has revealed that dysregulation of the mitogen-activated protein kinase (MAPK) signaling pathway is a recurrent and unifying characteristic across many pediatric and adult CNS tumor entities. Alterations affecting upstream receptor tyrosine kinases (RTKs), RAS GTPases, RAF kinases, and other associated regulators contribute to MAPK signaling pathway hyperactivation, shaping tumor behavior, therapy response and resistance. These aberrations ranging from hotspot mutations such as BRAF V600E and oncogenic fusions like BRAF–KIAA1549 are particularly enriched in gliomas and glioneuronal tumors, highlighting MAPK signaling as a key oncogenic driver. The expanding availability of molecularly targeted compounds, including selective inhibitors of RAF, MEK and ERK, has begun to transform treatment approaches for specific molecular subtypes. However, the clinical benefit of MAPK-directed therapies is frequently limited by restricted blood–brain barrier (BBB) penetration, intratumoral heterogeneity, parallel pathway reactivation, and an immunosuppressive tumor microenvironment (TME). In this review, we synthesize current knowledge on MAPK pathway alterations in CNS tumors and evaluate the therapeutic landscape of MAPK inhibition, with emphasis on approved agents, emerging compounds, combination strategies, and novel drug-delivery technologies. We also discuss mechanisms that undermine treatment efficacy and highlight future directions aimed at integrating MAPK-targeted therapy into precision-based management of brain tumors. Full article

Glioblastoma multiforme (GBM) exhibits remarkable resistance to therapy, mainly due to its capacity to modulate regulated cell death pathways. Among these, apoptosis and autophagy are dynamically interconnected, determining cell fate under therapeutic stress. The interaction between beclin-1 and Bcl-2 proteins may represent a key molecular switch that controls whether glioma cells undergo survival or death. This review highlights the crucial role of the Bcl-2:beclin-1 complex in controlling apoptosis–autophagy axis in GBM, emphasising how survival signalling networks, including PI3K/AKT/mTOR, Ras/Raf/MEK/ERK, and PLCγ1/PKC pathways regulated by the TrkB receptor, modulate this balance. We summarise recent insights into how these pathways coordinate the shift between apoptosis and autophagy in glioma cells, contributing to drug resistance. Furthermore, we highlight how modulating this crosstalk can sensitise GBM to conventional and emerging therapies. Integrating new concepts of cell death reprogramming and systems-level signalling analysis, we propose that targeting the Bcl-2:beclin-1 complex and its upstream regulators could overcome the adaptive plasticity of glioblastoma multiforme and open new directions for combination treatment strategies. Full article

Melanocyte signaling through the MAPK pathway is orchestrated by NRas and relayed downstream via multiple effectors, such as RAF, Ral, and PI3K. In spite of their significance, the molecular mechanisms of signaling relay by NRas, their dynamics, and their potential as therapeutic targets remain unclear. Using multi-color single molecule localization microscopy (PALM and dSTORM), we resolved the mutual nanoscale organization of NRas, PI3K, and BRAF at the plasma membrane of fixed and live melanoma cells. Surprisingly, NRas and its oncogenic mutation Q61R colocalized with PI3K in mutual nanoclusters, where BRAF was also frequently present. In live cells, NRas and PI3K co-clustering declined, yet persisted over minutes. Clinically relevant perturbations revealed unexpected crosstalk within these nanoclusters and consequently, between the MAPK and PI3K pathways. Specifically, overexpression of the Ras binding domain (RBD) and PI3K inhibition by wortmannin disrupted NRAS-PI3K interactions, and reduced both pAKT and pERK levels and cancer cell proliferation. MEK inhibition with trametinib resulted in similar, yet more pronounced effects. Thus, our findings provide novel insights into NRAS-mediated signaling through nanoscale clusters and underscore their potential as therapeutic targets. Full article

Carcinogenesis is driven by aberrant activation of molecular signaling pathways governing cell proliferation, apoptosis, and differentiation. Among these, the RAS/RAF/MEK/ERK (RAS/MAPK) cascade is one of the most frequently dysregulated oncogenic pathways, driving tumor initiation and progression across diverse cancer types. Although inhibitors of BRAF and MEK have achieved clinical success in selected malignancies, adaptive resistance often undermines therapeutic durability. This has spurred interest in alternative nodes within the pathway. The kinase suppressor of Ras (KSR) is a scaffold protein that organizes RAF, MEK, and ERK into functional complexes, ensuring efficient and sustained signal transmission. Once regarded as a passive structural component, KSR1 is now recognized as an active regulator of pathway dynamics. Emerging evidence indicates that KSR1 overexpression promotes cancer cell proliferation and survival, while genetic or pharmacologic inhibition of KSR1 attenuates RAS/MAPK signaling and suppresses tumor growth in preclinical models. In this review, we provide a comprehensive overview of accessory and scaffold proteins modulating the RAS/MAPK pathway, with a particular focus on KSR1. We highlight its structural and functional properties, summarize preclinical evidence for KSR1-targeted interventions, and discuss its therapeutic potential in cancer, with emphasis on hepatocellular carcinoma (HCC). Full article

The ERK1/2 and PI3K signaling pathways play important roles in cellular proliferation, survival, differentiation, and metabolism. In cancer, these pathways are frequently dysregulated and overactivated, resulting in poor patient prognosis and resistance to treatment. These pathways are activated by receptor tyrosine kinases and send downstream signals to effectors such as RAS, RAF, MEK, AKT, and mTOR. In this review, we highlight the key components of the ERK1/2 and PI3K pathways, the roles they play in tumor progression, and the development of inhibitors and combination therapies designed to enhance therapeutic outcomes and address treatment resistance. Our review demonstrates the need and promise for future research and clinical trials for inhibitors and combination therapies for the ERK1/2 and PI3K pathways in cancer. Full article

ELK1 is a Transcription factor (TF) belonging to the ETS-domain TF family, mainly activated via RAS-RAF-MEK-ERK signaling. As a nethermost pathway molecule, ELK1 binds to Serum-response elements (SREs) and directly regulates the transcription of Immediate early genes (IEGs) including FOS and EGR1. Due to ELK1’s influence on key cellular processes such as proliferation, migration, apoptosis evasion, and Epithelial-to-mesenchymal transition (EMT), its role as a key contributor to tumorigenesis is emerging. In recent years, elevated expression and/or activation of ELK1 has been reported in various malignancies, including lung, breast, prostate, colorectal, blood, gastric, liver, cervical, thyroid and ovarian cancer. ELK1 acts primarily through direct DNA binding but also through interaction with other oncogenes, noncoding RNA molecules, TFs, and upstream kinases (other than ERK1/2), thus participating in diverse axes of transcriptional regulation. Its crucial role in IEG expression has been particularly implicated in cancer progression, metastasis, and drug resistance. Owing to its role in multiple cellular functions and its subsequent oncogenic potential, further elucidation of intracellular ELK1 interactions is of paramount importance. This review aims to summarize current evidence on ELK1’s involvement in solid tumors, dissect reported mechanistic roles, and highlight recent insights that could fuel future ventures of high translational interest. Full article

Reciprocal signaling between acute myeloid leukemia (AML) cells and the surrounding bone-marrow microenvironment (BMME) promotes AML progression through several mechanisms. One of the most important mechanisms is the induction of Galectin-3 (Gal-3) expression by AML cells and bone marrow mesenchymal stromal cells (BM-MSCs). Emerging evidence indicates that Gal-3 upregulation in the BMME promotes AML cell adhesion and survival, leading to the development of chemotherapy resistance, relapse, and poor prognosis. Identifying the biological function and critical signaling pathways of Gal-3 may contribute to overcoming acquired drug resistance and preventing post-treatment relapse. Gal-3 is involved in several molecular signaling pathways, including PI3K/AKT/mTOR, Ras/Raf/MEK/ERK, JAK/STAT, JNK, Wnt/β-catenin, PLC/PKC and NF-κB, which are interconnected to promote AML cell survival and resistance to chemotherapy. This review focuses on the biological effects, molecular mechanisms of action and regulation of Gal-3 in the pathogenesis and progression of AML. The therapeutic potential of potent synthetic small-molecule Gal-3 inhibitors in high-risk patients with AML is also discussed based on preclinical and clinical evidence from several human diseases. Currently, the effect of these Gal-3 inhibitors in AML has not been investigated either in vitro or in vivo. The findings provide a rationale for targeting Gal-3 that may be a very promising therapeutic approach, especially for patients with relapsed/refractory AML, and may enhance the efficacy of conventional chemotherapeutic drugs and/or immune checkpoint inhibitors. Full article