Search Results (676)

Cucurbitacin B belongs to a group of tetracyclic triterpenoids and exerts a number of biological effects, including anti-inflammatory and anticancer activities. We previously demonstrated that cucurbitacin B down-regulated tumor necrosis factor (TNF) receptor 1 (TNF-R1) expression and prevented activation of the transcription factor nuclear factor κB in response to a TNF-α stimulation. The present study shows that cucurbitacin B promoted the ectodomain shedding of TNF-R1 by generating a soluble form that accumulated in the culture medium of human lung adenocarcinoma A549 cells. Of the eight tetracyclic and pentacyclic triterpenoids consisting of an α,β-unsaturated carbonyl group that were examined, only cucurbitacin B promoted TNF-R1 ectodomain shedding. Cucurbitacin B-induced TNF-R1 shedding was attenuated by TNF-α protease inhibitor 2 and the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor U0126, but not by the p38 MAPK inhibitor SB203580 or the c-Jun N-terminal kinase (JNK) inhibitor SP600125. Consistent with these results, cucurbitacin B promoted the rapid phosphorylation of rapidly accelerated fibrosarcoma 1 (RAF1) and ERK, but exerted minimal effects on the phosphorylation of p38 MAPK and JNK. Collectively, these results demonstrate that cucurbitacin B selectively activated the RAF1-MEK-ERK pathway, which was essential for TNF-R1 ectodomain shedding. Full article

The role of adjuvant therapy in stage III melanoma is well established in clinical practice. Because stage IIB–IIC melanoma carries a risk of recurrence and melanoma-specific mortality comparable to that of stage III disease, adjuvant approaches have also been developed for patients with thick stage II tumors. Both pembrolizumab and nivolumab have demonstrated efficacy in reducing the risk of local and distant recurrence in patients with high-risk stage II melanoma, whereas evidence supporting the use of BRAF-MEK inhibitors in this setting remains inconclusive. Combinations of immune checkpoint inhibitors, as well as immunotherapy combined with mRNA-based vaccines, are currently under investigation in clinical trials. However, given the non-trivial risk of immune-related adverse events, careful selection of patients with stage II disease who are most likely to derive meaningful benefit from adjuvant therapy is essential. In this context, several clinicopathologic variables and gene expression profiling-based prognostic tools have been proposed to refine risk stratification. To date, however, none of these instruments have been incorporated into routine clinical practice, and no validated predictive biomarkers are available. Accordingly, optimal patient selection for adjuvant therapy remains an important unmet clinical need in early-stage melanoma. Full article

Noonan syndrome (NS) is a paradigmatic rare, genetically heterogeneous, multisystem disorder belonging to the RASopathies family, caused by dysregulated RAS/MAPK signaling. It is characterized by distinctive craniofacial features, postnatal short stature, and a high prevalence of congenital cardiac defects, with pulmonary valve stenosis (PS) and hypertrophic cardiomyopathy (HCM) being the hallmark lesions. First described by Dr. Jacqueline Noonan in 1968, the molecular era began with the discovery of PTPN11 mutations in 2001, revolutionizing diagnosis, risk stratification, and understanding of pathogenesis. Strong genotype–phenotype correlations now guide prognosis and personalized management; for instance, RAF1 and RIT1 variants confer a high risk of severe, early-onset HCM, while PTPN11 is strongly linked to dysplastic PS. Cardiac involvement remains the central determinant of long-term outcomes, requiring continuous surveillance from the prenatal period through adulthood. Management is inherently multidisciplinary, addressing endocrine, hematologic, neurodevelopmental, and oncologic aspects. Recent consensus statements emphasize the critical need for structured transition from pediatric to adult care. Novelty arises from the potential of MEK inhibitors as targeted therapies for severe HCM and lymphatic complications. This review provides a comprehensive update on NS, integrating foundational clinical knowledge with contemporary molecular insights, advanced cardiologic management, and emerging frontiers in therapy and diagnostics, underscoring the necessity of a proactive, lifelong, and personalized care approach. Full article

Epidermal hyperinnervation is a major cause of intractable itch in barrier dysfunction conditions such as atopic dermatitis. Keratinocyte-derived semaphorin 3A (Sema3A) suppresses epidermal hyperinnervation, but its expression is markedly reduced in barrier-disrupted skin. Although konjac ceramide (kCer) has been reported to act as a Sema3A-like ligand, the mechanisms by which it regulates Sema3A expression in keratinocytes remain unclear. Normal human epidermal keratinocytes (NHEKs) were treated with kCer, konjac glucosylceramide (kGlcCer), or C24 ceramide. Sema3A mRNA and protein levels were assessed by quantitative real-time PCR and enzyme-linked immunosorbent assay, respectively. The involvement of intracellular signaling was examined using mitogen-activated protein kinase (MAPK) inhibitors, activator protein-1 (AP-1) inhibitors, retinoic acid-related orphan receptor alpha (RORα) inverse agonists, and siRNAs targeting c-Jun, c-Fos, and RORα. kCer induced Sema3A expression in NHEKs more potently than kGlcCer or C24 ceramide and promoted Sema3A protein secretion. Pharmacological inhibition or genetic knockdown of MEK1/2, JNK, AP-1 components, or RORα significantly attenuated kCer-induced Sema3A expression, indicating involvement of the MAPK/AP-1 signaling axis and RORα. kCer upregulates Sema3A expression in human keratinocytes through MAPK/AP-1 signaling and RORα, suggesting it may represent a promising antipruritic agent for epidermal hyperinnervation associated with skin barrier dysfunction. Full article

Juvenile myelomonocytic leukemia (JMML) is a rare, aggressive myeloproliferative neoplasm of early childhood characterized by constitutive activation of the RAS-MAPK signaling pathway. RASopathies are a heterogeneous group of complex genetic disorders arising from germline mutations that dysregulate RAS-MAPK signaling. Noonan syndrome, CBL syndrome, and neurofibromatosis type 1 (NF1) are the three major RASopathies predisposing to JMML. More than 90% of JMML cases harbor germline or somatic mutations in one of five canonical driver genes—PTPN11, NRAS, KRAS, NF1, or CBL—establishing JMML as the prototypical malignant manifestation of RASopathy biology. The fifth edition of the World Health Organization Classification of Tumours reclassified JMML as a myeloproliferative neoplasm while the International Consensus Classification adopted JMML under pediatric and/or germline mutation-associated disorders, introducing a JMML-like category for cases lacking five canonical mutations but harboring emerging drivers such as SH2B3::LNK alterations and ALK::ROS1 fusions. The distinction between germline and somatic mutations profoundly influences prognosis: e.g., germline PTPN11-associated myeloproliferations and many germline CBL cases undergo spontaneous resolution, whereas somatic PTPN11- and NF1-mutated JMML is more aggressive and requires prompt allogeneic hematopoietic stem cell transplantation. DNA methylation profiling has emerged as the most robust prognostic framework, with consensus defining high-, intermediate-, and low-methylation subgroups that independently predict outcome. Both genotype and DNA methylation subclassification have been integrated into clinical decision-making, incorporating pretransplant azacitidine, watch-and-wait approaches for favorable-risk patients, and emerging targeted therapies including MEK inhibitors. This review synthesizes recent advances in understanding JMML as a bona fide RASopathy; provides a diagnostic algorithm, molecular landscapes, and prognostic models; and highlights opportunities for molecularly targeted therapeutic intervention. Full article

Targeted inhibition of the MAPK pathway with BRAF and MEK inhibitors (BRAFi/MEKi) produces rapid tumor regressions in BRAF V600-mutant melanoma, yet most patients ultimately develop acquired resistance. Resistance is not solely a tumor-cell-intrinsic phenomenon; it is accompanied by time-dependent remodeling of the tumor immune microenvironment (TIME) that can shape sensitivity to immune checkpoint inhibitors (ICIs) and inform rational combination or sequencing strategies. Early during MAPK inhibition, melanomas often display increased melanoma antigen expression and enhanced CD8⁺ T-cell infiltration, along with reduced immunosuppressive cytokines, suggesting a transient “immune-permissive” window. However, the same period can show induction of PD-L1 and T-cell exhaustion markers, foreshadowing adaptive immune resistance. At progression, immune-favorable features may diminish and immune evasion mechanisms, such as impaired antigen presentation and MHC-I downregulation, can become prominent and associate with resistance to immunotherapy. Here we review the temporal dynamics of TIME under MAPK inhibition, mechanistic links between resistance programs and immune remodeling, including signaling adaptation, focal adhesion/FAK signaling, dendritic cell dysfunction, antigen-presentation defects, and lymphatic/perilymphatic adipose remodeling, and practical biomarker opportunities across baseline, on-treatment, and progression timepoints. We also summarize emerging therapeutic strategies for post-resistance disease, including optimized ICI combinations, triple therapy concepts, and novel approaches such as combining FAK inhibition with RAF-MEK “clamp” therapy. Finally, we highlight key gaps and propose a framework for longitudinal sampling, standardized multi-omics integration, and TIME-informed trial design. The key distinguishing feature of this review is its time-resolved perspective on TIME remodeling, which links baseline immune contexture, early treatment-induced immune permissiveness, and the immune-evasive state that emerges during acquired resistance. Full article

Plexiform neurofibromas (pNF1s) are benign peripheral nerve sheath tumors caused by NF1 loss, leading to dysregulated RAS/mitogen-activated protein kinase (MAPK) signaling. While the mitogen-activated protein kinase kinase (MEK) inhibitors, selumetinib and mirdametinib, can reduce tumor volume, surgical resection remains the primary treatment for immediate debulking and symptom relief. Complete removal is often limited by tumor infiltration along nerve plexuses, and residual tumors may undergo postsurgical tissue remodeling, producing localized regions of stiffened extracellular matrix (ECM). The impact of ECM stiffness on pNF1 growth and drug responses remains unclear. Using immortalized patient-derived pNF1 tumor cell lines cultured in 3D hydrogels with defined stiffness (1.5 kPa, soft; 7 kPa, stiff), we found that stiff ECM promoted spread morphology, increased growth, and progressive intracellular softening. Stiff ECM also reduced lysyl oxidase (LOX) expression, suggesting mechanoadaptive ECM remodeling, and increased P-glycoprotein expression. Under the same conditions, stiff ECM was associated with reduced sensitivity to selumetinib. These results provide the first evidence that ECM stiffening, including that plausibly associated with postsurgical remodeling, may contribute to pNF1 growth and reduced sensitivity to selumetinib in this 3D pNF1 culture model. Our findings highlight mechanobiology as a key regulator of tumor behavior and support further investigation of ECM-targeted strategies to improve outcomes in neurofibromatosis type 1 (NF1). Full article

Neurofibromatosis type 1 (NF1) patients are predisposed to develop plexiform neurofibromas (PNFs). By cross-comparison of RNA sequencing and RUNX1-CHIP sequencing data on mouse PNFs, we found that transcripts encoding the NF1-interacting p97/valosin-containing protein (VCP) gene are overexpressed in PNFs. Co-immunoprecipitation confirmed that VCP bounded to neurofibromin. Western blot and immunostaining confirmed VCP overexpression in both mouse and human PNFs. Treatment of primary mouse PNF Schwann cells with CB-5083, a p97/VCP inhibitor, led to accumulation of poly-ubiquitinated proteins and generation of irresolvable proteotoxic stress. Pharmacological or genetic inhibition of VCP reduced mouse PNF cell-derived sphere number, and genetic inhibition of Vcp in Schwann cell precursors decreased tumor-like lesion numbers in a cell transplantation model. In vivo treatment with CB-5083 in Nf1^fl/fl;DhhCre PNF mice significantly inhibited cell proliferation, increased cell apoptosis and reduced PNF volume. The combination with a MEK inhibitor did not increase efficacy compared to the single agent, supporting the hypothesis that VCP functions in parallel to, and may be modulated by, RAS–MAPK signaling under stress or oncogenic conditions. The significant effects of VCP inhibition in this pre-clinical study suggest a potential novel therapy for patients with PNFs. Full article

Background/Objectives: Langerhans cell histiocytosis (LCH) is a rare myeloid neoplasm characterized by the clonal proliferation of Langerhans-like dendritic cells and constitutive activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK-ERK) signaling pathway. Nearly 80% of ERK pathway activation can be attributed to B-Raf proto-oncogene, serine/threonine kinase (BRAF V600E), and mitogen-activated protein kinase kinase 1 (MAP2K1) variants, with BRAF V600E specifically detected in approximately 50% of pediatric LCH cases and associated with a higher risk of severe disease and treatment failure. The use of the HistioTrak clinical assay to detect the presence of BRAF V600E mutations in peripheral blood mononuclear cells (PBMCs) has emerged as a useful diagnostic tool and biomarker. Methods: This study is a single-center retrospective study that explores the favorable outcomes of treatment with trametinib on a small number of patients with LCH. We retrospectively analyzed the records of 11 children with LCH treated with trametinib at diagnosis as front-line therapy (n = 6), due to progressive disease (n = 3) or intolerance (n = 1) to chemotherapy, or at relapse (n = 1). Results: HistioTrak identified the presence of BRAF V600E PBMCs in five patients. In this small single-center retrospective cohort, trametinib was associated with favorable short-term outcomes in all patients, and serial HistioTrak testing appeared feasible in selected patients. Conclusions: Prospective studies are needed before routine diagnostic or monitoring use can be recommended. Full article

Advances in pediatric oncology have markedly improved survival, shifting attention toward long-term treatment-related morbidity. Targeted agents and immune-based therapies are now widely used across pediatric malignancies and selected non-malignant conditions, often for prolonged periods and during critical windows of growth and development. Because many therapeutic targets regulate physiological pathways involved in growth, pubertal maturation, gonadal function, bone metabolism, and energy homeostasis, clinically relevant endocrine toxicity may emerge during treatment or become apparent only with extended follow-up. This narrative review summarizes pediatric evidence on endocrine and metabolic effects associated with major classes of targeted and immune-based therapies, including tyrosine kinase inhibitors, mTOR inhibitors, MAPK-pathway inhibitors (BRAF/MEK), TRK inhibitors, ALK inhibitors, immune checkpoint inhibitors, and immune effector therapies. Distinct patterns of endocrine vulnerability emerge across drug classes: growth impairment and bone–mineral alterations are most consistently reported with tyrosine kinase inhibitors; weight gain and metabolic changes predominate with MAPK-, TRK-, and ALK-targeted agents; immune checkpoint inhibitors are characterized by early, multi-axis immune-related endocrinopathies with a high likelihood of permanent hormone deficiency once established. In contrast, endocrine abnormalities observed after immune effector therapies largely reflect indirect effects of systemic inflammation, corticosteroid exposure, and prior hematopoietic stem cell transplantation rather than direct endocrine toxicity. Given the limited pediatric-specific data, frequent confounding by multimodal therapy, and the potential for delayed or irreversible endocrine sequelae, structured endocrine monitoring and long-term survivorship care are essential for children exposed to modern anticancer therapies. Full article

Mitogen-activated protein kinase kinase kinase 1 (MAP3K1) possesses dual enzymatic functions, i.e., kinase and E3 ubiquitin ligase activities, orchestrating proliferation, survival, apoptosis, DNA damage response, and immune modulation. Recent genomic and mechanistic studies have revealed MAP3K1’s paradoxical, context-dependent roles as both an oncogene and a tumor suppressor. We discuss MAP3K1’s multidomain architecture, featuring an N-terminal RING and PHD domain (E3 ligase activity), a TOG domain (microtubule dynamics), and a C-terminal kinase domain, enabling the integration of c-jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), and nuclear factor kappa B (NF-κB) signaling pathways. MAP3K1 functions as a molecular switch balancing survival and apoptosis, with caspase-3 cleavage at Asp878 activating pro-apoptotic JNK/p38 signaling. Genomic analyses across >35 cancer types reveal MAP3K1 alterations at frequencies of <1–14%, highest in breast and endometrial cancers. These alterations show tissue specificity: loss-of-function mutations predominate in hormone receptor-positive breast cancer with a favorable prognosis, whereas gain-of-function mutations in melanoma activate oncogenic ERK signaling. MAP3K1 mutations predict response to mitogen-activated protein kinase kinase (MEK) and phosphoinositide 3-kinase (PI3K) inhibitors, with mutant cancers showing higher MEK inhibitor response than wild-type tumors. Despite substantial progress, critical gaps remain regarding MAP3K1’s E3 ligase substrates, context-dependent activity determinants, and therapeutic strategies. Addressing these through inhibitor development, biomarker validation, and mechanistic studies will accelerate potential clinical translation of MAP3K1 biology. Full article

Herbal melanin (HM), previously reported for its antiproliferative and pro-apoptotic properties, has garnered interest as a promising anti-colorectal cancer drug. However, HM’s biological effects and underlying molecular mechanisms and the related signaling pathways in colorectal cancer (CRC) cell motility are poorly investigated. To evaluate the impact of various concentrations (50, 100, and 200 μg/mL) of HM on cell migration, invasion, and tumorigenicity on human HT29 and SW620 CRC cell lines, a real-time cell analyzer instrument and colony formation assays were employed, respectively. An angiogenesis-related protein array was also used, and the levels of protein expression contributing to colony formation and extracellular proteolysis-driven cell migration and invasion, such as E-cadherin, N-cadherin and urokinase-type plasminogen activator receptor (uPAR), were monitored using Western blotting and RT-qPCR technologies. HM significantly decreased CRC cell motility, invasiveness, and formation of colonies, associated with E-cadherin upregulation and N-cadherin downregulation. In addition, HM specifically inhibited uPAR expression levels, which were also decreased by the pharmacological mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor UO126 and Jun N-terminal kinase (JNK) inhibitor SP600125, in both CRC cell lines, including metastatic CRC (mCRC) SW620 cell line. Addition of HM to cells pretreated with JNK and MEK inhibitors attenuated the blockade of JNK and ERK phosphorylation and alleviated HM-downregulated uPAR expression and HM-inhibited mCRC cell migration. In conclusion, our in vitro studies demonstrate that HM exhibits an inhibitory effect on CRC migration and invasiveness, associated with uPAR downregulation through JNK and ERK pathways. Full article

Background/Objectives: BRAF and/or MEK inhibitors are widely used for patients with BRAF-mutated melanoma, but no biomarkers of response or resistance are currently available. Besides adverse events in different organs, target therapy with BRAF and/or MEK inhibitors may induce the onset of immune-related adverse events (irAEs) that have been considered as possible biomarkers of good prognosis in patients with melanoma. Methods: To investigate this aspect, we analyzed the occurrence of irAEs in a cohort of 158 patients treated with BRAF and MEK inhibitors. We also analyzed by flow cytometry the subsets of circulating immune cells in the patients who developed irAEs and matched controls. Results: We found that irAEs occurred in 3 out of 101 patients (3%) who experienced adverse events. These three patients did not exhibit any specific clinical features or circulating immune cell subtypes that could be associated with a positive response to treatment. However, the onset of toxicity in the entire patient cohort was associated with longer progression-free survival. Notably, the frequency of circulating follicular helper T cells increased in all examined patients during the first two months of treatment. Conclusions: The small sample size prevents us from determining whether irAEs are effectively caused by BRAF/MEK inhibitors or if they are a random event. Additionally, we cannot conclude whether irAEs are related to a better outcome. Nevertheless, we note that BRAF/MEK inhibition may alter the composition of circulating immune cells in melanoma patients. This aspect should be investigated further before proposing combinations of target therapies and immunotherapies. Full article

Neurofibromatosis type 1 (NF1) and NF2-related schwannomatosis (NF2-SWN) are major genetic tumor predisposition syndromes characterized by progressive, often debilitating neoplasms of the peripheral and central nervous systems. Over the past five years, substantial advances in molecular genetics, signaling biology, and targeted therapeutic development have reshaped diagnostic and management paradigms for both disorders. This Perspective synthesizes recent developments, including gene-based reclassification, emergence of MEK inhibitor therapy in NF1, renewed evaluation of bevacizumab and kinase-pathway inhibitor brigatinib, the discovery of a novel TβR1-RKIP pathogenic axis, and a brain-penetrant HDAC inhibitor in NF2-SWN. These insights highlight a shift toward precision-medicine strategies and mechanistically driven therapies poised to redefine future clinical care. Full article

Background/Objectives: Protein kinases play crucial roles in signal transduction pathways that regulate growth and differentiation in Trypanosoma cruzi. These protein kinases are attractive targets to develop new drugs to treat Chagas disease. Methods: We used several protein kinase inhibitors targeting the p38 MAPK, MEK, and ERK pathways to evaluate their effects on the in vivo phosphorylation status of T. cruzi proteins, particularly DNA polymerase beta (TcPolβ). We also used Genistein, a protein tyrosine kinase inhibitor, to assess its effects on global protein phosphorylation and TcPolβ phosphorylation. Also, we investigated the effect of oxidative stress on global tyrosine phosphorylation. Finally, we determined the phosphorylation sites on TcPolβ by the protein kinases TcPKC2 and TcWee570 in vitro. Results: p38 MAPK and MEK protein kinase inhibitors inhibited approximately 50% of the Ser/Thr phosphorylation of TcPolβ. Genistein inhibited both Ser/Thr and Tyr phosphorylation of several polypeptides in epimastigotes. Oxidative stress increases global Tyr phosphorylation by about twofold and also TcPolβ phosphorylation. TcPKC2 and TcWee570 were able to phosphorylate TcPolβ at both Ser/Thr and Tyr residues. Conclusions: Small-molecule protein kinase inhibitors can affect the phosphorylation status of TcPolβ in vivo. Since Genistein can inhibit both Ser/Thr and Tyr protein phosphorylation, and TcPKC2 and TcWee570 can phosphorylate both Ser/Thr and Tyr residues, it suggests the existence of dual protein kinases in T. cruzi. However, this possibility must be further studied. Full article