Search Results (1,941)

Background/Objectives: Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults, with a poor prognosis and limited therapeutic options. This study aimed to repurpose methylstat, a selective histone demethylase inhibitor, as a novel anti-glioma agent. We characterized its anti-proliferative efficacy, elucidated mechanisms of cell cycle regulation, and evaluated its blood–brain barrier (BBB) permeability potential. Methods: Compounds with transcriptional profiles enriched for cell cycle arrest and tumor-suppressive pathways were identified via Connectivity Map (CMAP) analysis. Methylstat was selected based on its high connectivity score and favorable physicochemical properties. In vitro assays were performed to evaluate its effects on cell viability, proliferation, cell cycle progression, and expression of related molecular markers in U251 and HOG glioma cell lines. Molecular docking and 200 ns molecular dynamics (MD) simulations were performed to evaluate the binding mode and stability of the Methylstat–JMJD2A complex. An in vitro BBB model was established to assess the ability of Methylstat to cross the BBB. Results: Methylstat significantly inhibited glioma cell proliferation in a dose-dependent manner without inducing apoptosis. It caused G1-phase arrest in U251 cells and G2-phase arrest in HOG cells. Mechanistically, methylstat downregulated cyclins and cyclin-dependent kinases via the p53/p21 pathway. Additionally, methylstat reduced the expression of JMJD2A and its downstream targets, including PDK1, AKT, and mTOR. Molecular docking studies and 200 ns MD simulations confirmed the stable binding of methylstat to the catalytic pocket of JMJD2A, effectively inhibiting its enzymatic activity. HPLC analysis confirmed that methylstat could penetrate the in vitro BBB model to varying extents. Conclusions: Methylstat is a promising small-molecule agent that effectively suppresses glioma cell growth by modulating key cell cycle regulators. Its ability to cross the BBB highlights its potential as a novel therapeutic strategy for GBM and other brain tumors. Full article

Background/Objectives: Hepatitis B virus (HBV) infection poses a major global health challenge, with current therapies like nucleos(t)ide analogs and pegylated interferon alpha offering limited functional cure rates due to persistent HBsAg-driven immune tolerance. This study aimed to develop a targeted immunoadsorption system using a high-affinity humanized anti-HBsAg monoclonal antibody for efficient HBsAg and viral particle clearance, providing a novel approach to overcome therapeutic bottlenecks in chronic hepatitis B (CHB). Methods: A murine anti-HBsAg monoclonal antibody was humanized via complementarity-determining region grafting, resulting in HmAb-12 (equilibrium dissociation constant, K_D = 0.36 nM). A stable Chinese Hamster Ovary K1 (CHO-K1) cell line was established for high-yield expression (fed-batch yield: 8.31 g/L). The antibody was covalently coupled to agarose microspheres (coupling efficiency > 95%) to prepare the immunoadsorbent. Efficacy was evaluated through in vitro dynamic circulation assays with artificial sera and preclinical trials using an integrated blood purification system in two CHB participants. Clearance rates for HBsAg and HBV DNA were quantified, with safety assessed via blood component monitoring. Results: In vitro, a single treatment cycle achieved HBsAg clearance rates of 70.14% (high antigen load, >10⁵ IU/mL) and 92.10% (low antigen load, ~3000 IU/mL). Preclinically, one treatment session resulted in acute HBsAg reductions of 78.30% and 74.31% in participants with high and moderate antigen loads, respectively, alongside HBV DNA decreases of 65.66% and 73.55%. Minimal fluctuations in total protein and albumin levels (<15%) confirmed favorable safety profiles, with no serious adverse events observed. Conclusions: Preliminary findings from this study indicate that the HBsAg-specific immunoadsorption system can achieve efficient HBV antigen clearance with an initial favorable safety profile in a small cohort. These results support its further investigation as a potential therapeutic strategy for functional cure in CHB. Future work will focus on validating these findings in larger studies and exploring the system’s combinatory potential with existing blood purification platforms. Full article

Antibody–drug conjugates (ADCs) are a rapidly advancing class of targeted cancer therapeutics that couple the antigen specificity of monoclonal antibodies (mAbs) with the potent cytotoxicity of small-molecule drugs. In their core design, a tumor-targeting antibody is covalently linked to a cytotoxic payload via a chemical linker, enabling the selective delivery of highly potent agents to malignant cells while sparing normal tissues, thereby improving the therapeutic index. Humanized and fully human immunoglobulin G1(IgG1) antibodies are the most common ADC backbones due to their stability in systemic circulation, robust Fcγ receptor engagement for immune effector functions, and reduced immunogenicity. Antibody selection requires balancing tumor specificity, internalization rate, and binding affinity to avoid barriers to tissue penetration, such as the binding-site barrier effect, while emerging designs exploit tumor-specific antigen variants or unique post-translational modifications to further enhance selectivity. Advances in antibody engineering, linker chemistry, and payload innovation have reinforced the clinical success of ADCs, with more than a dozen agents FDA approved for hematologic malignancies and solid tumors and over 200 in active clinical trials. This review critically examines established and emerging conjugation strategies, including lysine- and cysteine-based chemistries, enzymatic tagging, glycan remodeling, non-canonical amino acid incorporation, and affinity peptide-mediated methods, and discusses how conjugation site, drug-to-antibody ratio (DAR) control, and linker stability influence pharmacokinetics, efficacy, and safety. Innovations in site-specific conjugation have improved ADC homogeneity, stability, and clinical predictability, though challenges in large-scale manufacturing and regulatory harmonization remain. Furthermore, novel ADC architectures such as bispecific ADCs, conditionally active (probody) ADCs, immune-stimulating ADCs, protein-degrader ADCs, and dual-payload designs are being developed to address tumor heterogeneity, drug resistance, and off-target toxicity. By integrating mechanistic insights, preclinical and clinical data, and recent technological advances, this work highlights current progress and future directions for next-generation ADCs aimed at achieving superior efficacy, safety, and patient outcomes, especially in treating refractory cancers. Full article

Background/Objectives: Neutrophil-to-lymphocyte ratio (NLR), a marker of systemic inflammation, has prognostic value in non-small cell lung cancer (NSCLC), but its longitudinal performance in routine care is unclear. We evaluated baseline and 12-month changes in NLR and hemoglobin in a single-center, Eastern European cohort. Methods: In this retrospective study, 180 adults with histologically confirmed NSCLC, diagnosed May 2022–April 2024 at a Romanian tertiary center, were followed until 30 April 2025. Baseline demographics, tumor characteristics, molecular profiles, laboratory parameters, and treatments were extracted from electronic health records. Progression-free survival (PFS) was the primary endpoint, overall survival (OS) the secondary, analyzed using Kaplan–Meier curves and Cox proportional hazards models. An additional treatment-start-anchored sensitivity analysis in treated patients was conducted. Results: The cohort (median age 67.8 years, 68.9% stage IV) received chemo-immunotherapy (58.9%), immunotherapy (26.7%), chemotherapy (9.4%), or supportive care (5.0%). Median for PFS was 8.2 months and for OS 14.5 months. A high baseline NLR (≥3, 58.9%) increased progression risk (HR 1.60, 95% CI 1.10–2.32, p = 0.014), with a trend for worse OS (HR 1.45, 95% CI 0.99–2.12). A 12-month NLR increase (62.2%) further elevated progression risk (HR 1.52, 95% CI 1.05–2.20, p = 0.026). Low hemoglobin (<12 g/dL) had a non-significant effect (HR 1.38, 95% CI 0.97–1.96, p = 0.074). PD-L1 ≥ 50% and chemo-immunotherapy correlated with longer PFS. Findings were consistent in the treatment-start anchored sensitivity analysis. Conclusions: These exploratory findings suggest that inexpensive hematologic markers can complement clinical assessment in advanced-stage NSCLC; prospective multi-center validation is warranted. Full article

Afatinib and osimertinib are current treatment options for non-small cell lung cancer (NSCLC) patients with uncommon epidermal growth factor receptor (EGFR) mutations, although their efficacy is limited. To explore potentially effective drugs for these patients, we evaluated the efficacy of conventional EGFR tyrosine kinase inhibitors (TKIs) and novel third-generation (3G) TKIs using in vitro models. Ba/F3 cells transformed with each of the five most frequent uncommon EGFR mutations, Del18 (delE709_T710insD), E709K, G719A, S768I, and L861Q, were used. The growth inhibitory effects of five novel 3G-TKIs, almonertinib, lazertinib, furmonertinib, rezivertinib, and befotertinib, in addition to currently available TKIs, were evaluated. We also explored for secondary resistant mutations to afatinib or osimertinib and TKIs that can overcome these resistances. Afatinib was active against all uncommon EGFR mutations tested. The 3G-TKIs were all active against the L861Q mutation and were inactive against the S768I mutation. Furmonertinib and befotertinib showed efficacy against exon 18 mutations (Del18, E709K, and G719A). In the acquired resistance models to afatinib or osimertinib, we found T790M or a novel T725M secondary mutation, respectively, both of which could be overcome by lazertinib. However, some afatinib-resistant cells acquired V769L/M secondary mutations that were refractory to all EGFR-TKIs tested. In conclusion, afatinib exhibited broad activity and some 3G-TKIs showed promising efficacy in the front-line setting. Lazertinib is a potential second-line option after acquisition of resistance to afatinib or osimertinib. Full article

Small ruminant production is a significant sector of agricultural industry in Texas, USA. Heat stress has a negative effect on productivity and animal health. Cholecalciferol, a form of vitamin D₃, may enhance the function of immune cells and help ensure healthy immune function in farm animals exposed to heat stress. Practical applications of vitamin D₃ against infectious diseases can benefit from the protective effects of a delivery system comprised of soy protein isolate and stachyose in emulsion gel. The prebiotic oligosaccharide stachyose has shown to have a great potential as a substrate for beneficial intestinal bacteria, which are thought to modulate the immune system. Cellular and humoral immunity are both impaired in dairy animals under heat stress. The delivery of vitamin D₃ embedded within the soy protein isolate-stachyose emulsion gel resulted in a marked increase in 25-hydroxyvitamin D₃ [25-(OH)-D₃] concentration in blood serum. Chicken egg albumin (OVA)-immunized goats produced low anti-OVA immunoglobulin G (IgG) responses. In contrast, OVA-immunized goats fed vitamin D₃ within the soy protein isolate-stachyose emulsion gel diet strongly stimulated antibody production. These results show that anti-OVA IgG responses can be modulated in dairy goats using vitamin D₃, particularly if this vitamin is delivered in the form of emulsion gel. The results seem to depend on the highly hydrated gel matrix of soy protein isolate-stachyose at the low pH of the stomach as monitored by oxygen-17 (¹⁷O) and proton (¹H) nuclear magnetic resonance (NMR). In addition, the prebiotic nature of stachyose may boost beneficial gut bacteria, most notably for immune health and reducing the risk of infectious diseases. Full article

Plants are capable of responding to various environmental stresses by initiating the expression of genes that encode proteins involved in plant growth, fruit ripening, maintaining protein homeostasis, and combating heat stress (HS) by activating heat tolerance systems. The mechanism of resisting against HS is very intricate, and the molecular basis and involvement of the related gene network in Capsicum annuum L. are not fully understood. There are five different heat shock proteins (HSPs) reported in the literature, namely, small HSPs (sHSPs), CaHSP60s, CaHSP70s, CaHSP90s, and CaHSP100s, which play a pivotal role in heat stress response (HSR) in C. annuum. Heat shock factors (HSFs) and heat stress elements (HSEs) govern the transcriptional modifications and control the relative expression of heat shock proteins (HSPs). The heat stress response is the reprogramming of the molecular cascades involving the cell stress responses against the HSR, which is characterized by the increased production of molecular chaperones, which help the plants to counter the negative physiological impacts on proteins, induced by heat and other abiotic stresses. Therefore, understanding the detailed molecular mechanisms of C. annuum in response to extreme temperatures is critical for exploring how they will be affected by climate change and how they behave to cope with these varied climate extremes. This study is focused on providing a complete understanding of the molecular cascades in C. annuum L.’s response to HS, which starts with the sensation of HS signals and activation of the relative molecular cascades that are responsible for the activation of HSFs and initiate their primary targets, e.g., HSPs. Overall, this review provides deep insights into all the cellular responses during HS with a special focus on categorization and physiological aspects of HSPs and HSFs. Full article

Background/Objectives: Medium- and long-chain triacylglycerol (MLCT) and 2′-fucosyllactose (2′-FL) are functional ingredients abundant in human milk; however, their effects on small intestinal development and health remain largely unknown, and no research has explored their potential combined effects. Methods: In this study, growing C57BL/6 mice (3 weeks old) were fed diets without or with 2.5 g/100 g of MLCT, 2′-FL, or the combination (MLCT + 2′-FL; 5:1) for 21 days. Body weight, major organ indices, small intestinal morphology-related indicators (small intestinal length, villus height, crypt depth, villus height/crypt depth (V/C) ratio, and epithelial cell proliferation), and intestinal barrier function markers (goblet cell and Paneth cell count, protein expression of ZO-1 and occludin, and levels of sIgA and LPS) were measured. Results: In addition to the shared promotion of epithelial cell proliferation, MLCT intervention raised villus height and crypt depth, while 2′-FL intervention elevated Paneth cell count and sIgA levels. Notably, MLCT + 2′-FL intervention offered additional advantages (increasing the V/C ratio, goblet cell count, and expression of ZO-1 and occludin) without affecting crypt depth. 16S rRNA sequencing analysis of cecal contents revealed that all three interventions mainly affected beta diversity rather than alpha diversity, and enriched differentially abundant bacterial taxa: Erysipelotrichaceae, Faecalibaculum, UBA1819, and Faecalitalea in the MLCT group; Enterobacteriaceae, Escherichia, and Allobaculum in the 2′-FL group; Bifidobacterium, Romboutsia, Clostridia, and several other bacterial taxa in the MLCT + 2′-FL group. Conclusions: These results indicate that MLCT and 2′-FL interventions alone appear to provide different benefits for small intestinal development, and their combination may confer more comprehensive advantages. Full article

Background/Objectives: HNSCC is a highly aggressive malignancy marked by the dysregulation of the cell cycle. In HPV⁻ HNSCC, mutations in the CDKN2A gene frequently result in the loss of the p16 protein, a key inhibitor of the cyclin D1/CDK4/6 complex. This loss results in unchecked G1/S phase progression. The CDK4/6 inhibitor palbociclib has shown therapeutic potential in HPV⁻ HNSCC by inducing G1 phase arrest and reducing cell viability. In this study, we investigated the molecular mechanisms by which palbociclib affects cell viability in HPV⁻ HNSCC. Methods: Four HPV⁻ HNSCC cell lines were treated with palbociclib, and RNA sequencing was performed to assess changes in gene expression. Cell viability was measured using the MTT assay. To further investigate protein localization, interactions, and function, we used immunofluorescence staining, co-immunoprecipitation, small molecule inhibitors, and siRNA-mediated knockdown. Results: We demonstrate that palbociclib downregulates survivin, a protein that plays dual roles in mitosis and apoptosis, thereby inhibiting cell proliferation. We also found that survivin is overexpressed in HPV⁻ HNSCC. Inhibiting survivin dimerization using the compound LQZ-7i significantly reduces cell viability and promotes its export from the nucleus to the cytoplasm. Additionally, we identified USP1, a deubiquitinase, as both a downstream target of CDK4/6 and a key regulator of survivin stability. Inhibiting USP1 activity or silencing its expression significantly reduces survivin levels. Conclusions: Our findings highlight survivin as a critical mediator of cell proliferation in HPV⁻ HNSCC and suggest that targeting the CDK4/6-USP1-survivin axis may offer a promising therapeutic strategy. Full article

Three new series of indolizines (5a–f, 6a–f and 7a–g), functionalized with bromine or ethyl ester substituents on the pyridine ring, were designed and synthesized as promising anticancer agents. The synthesis of indolizine derivatives was carried out using the 1,3-dipolar cycloaddition of pyridinium N-ylides to ethyl propiolate as a key step. Spectral characterization (using NMR, FT-IR, HRMS and X-ray diffraction) showed that two types of cycloadducts 5a–f and 6a–f were obtained when the ylides generated by the 3-bromopyridinium salts were used as 1,3-dipoles in Huisgen cycloaddition reactions to ethyl propiolate. The anticancer effect of selected compounds was in vitro assessed against the National Cancer Institute (NCI) panel of 60 human tumor cells, at 10 μM concentration, with three compounds (5c, 6c and 7g) showing promising inhibitory activity on the growth of several cell lines including lung, brain, renal cancer and melanoma, as well as a cytotoxic effect against HOP-62 non-small cell lung cells (34% for compound 5c and 15% for compound 7g) and SNB-75 glioblastoma cells (15% for compound 5c and 14% for derivative 7c). Molecular docking revealed favorable binding affinities for 5c, 6c and 7g (–9.22 to –9.88 kcal/mol) at the colchicine-binding site of tubulin with key interactions involving βASN-258, βALA-317, and βLYS-352 residues for 5c, βASN-258 in case of 6c, and αVAL-181 and βLYS-254 for derivative 7g. According to the in silico ADMET analysis, the active compounds are predicted to exhibit good oral bioavailability, promising drug-like qualities and low toxicity risks. Full article

KRAS is the most frequently mutated oncogene in cancer. Its activating mutations are associated with aggressive tumor behavior and resistance to certain therapies, including anti-EGFR treatments in colorectal cancer. In particular, the KRAS G12C mutation, which accounts for approximately 3–4% of colorectal cancers (CRCs) and 12–14% of non-small cell lung cancers (NSCLCs), involves a cysteine substitution at codon 12. This has provided the opportunity to develop selective covalent inhibitors that trap the mutant protein in its inactive state. The first targeted therapies for KRAS G12C-mutant cancers comprise sotorasib and adagrasib, both of which have been authorized for use in patients with previously treated NSCLC and CRC. Nevertheless, despite the evidence of clinical activity for this class of agents, primary and acquired resistance, dose optimization, and toxicity management remain significant open challenges. In this review, we summarize recent advances in KRASG12C tumor biology and pharmacological targeting. We also provide additional insights to guide future efforts to overcome the limitations of the current approaches and implement the treatment of KRASG12C-mutant cancers. Full article

Autologous fat grafting of human lipoaspirate (LA) is increasingly used in reconstructive and cosmetic surgery for lipofilling and stem cell-rich “nanofat” reinjection for regenerative medicine. While commercial devices (e.g., REVOLVE and Puregraft) are available, many surgeons use non-standardized manual washing techniques, leading to inconsistent graft retention (20–80%). Moreover, no system can unite washing directly with mechanical processing to produce a nanofat-like product directly from raw LA. We developed a novel preparation device (PD) that is designed for peristaltic pump-driven washing of LA and can be seamlessly combined with our previously developed Emulsification and Micronization Device (EMD) into an automated closed-loop platform. Human LA samples were washed with the PD and compared to standard manual washing via visual colorimetric analysis. We then evaluated the mechanical processing of PD-washed LA using our EMD and assessed cell count, viability, and stromal vascular fraction-derived subpopulations (i.e., mesenchymal stem cells, endothelial progenitor cells (EPCs), pericytes, transit-amplifying (TA) progenitor cells, and supra-adventitial adipose stromal cells). Recirculating LA through the PD for at least one minute resulted in sufficient mixing, producing LA with equivalent color and quality to manual washing. Integrating the EMD within a platform enabled both washing and mechanical processing under peristaltic flow, enriching key subpopulations compared to manual methods. Thus, our fluidic platform effectively washes LA in a closed-loop system, minimizing LA tissue manipulation and opportunity for contamination while also simplifying the workflow for mechanical processing. Further refinement and automation of this platform would enhance the reproducibility and quality of small-volume fat grafts, cell-assisted lipotransfer, and stem/progenitor cell injections to promote wound healing and angiogenesis. Full article

Background: Freeze tolerance is an uncommon but highly effective strategy that allows certain vertebrates to survive prolonged exposure to subzero temperatures in a frozen, ischemic state. While past studies have characterized the metabolic and biochemical adaptations involved, including cryoprotectant accumulation and metabolic rate suppression, the contribution of post-transcriptional gene regulation by microRNAs (miRNAs) remains largely unexplored. This study investigated freeze-responsive miRNAs in cardiac tissue of the gray tree frog, Dryophytes versicolor, to better understand the molecular mechanisms that support ischemic survival and tissue preservation. Methods: Adult frogs were subjected to controlled freezing at −2.5 °C, and cardiac tissue was collected from frozen and control animals. Total RNA was extracted and analyzed via small RNA sequencing to identify differentially expressed miRNAs, followed by target gene prediction and KEGG pathway enrichment analysis. Results: A total of 3 miRNAs were differentially expressed during freezing, with significant upregulation of miR-93-5p and let-7b-5p and downregulation of miR-4485-3p. Predicted targets of upregulated miRNAs included genes involved in immune signaling pathways (e.g., cytokine–cytokine receptor interaction), steroid hormone biosynthesis, and neuroactive ligand–receptor interaction, suggesting suppression of energetically costly signaling processes. Downregulation of miRNAs targeting cell cycle, insulin signaling, and WNT pathways indicates possible selective preservation of cytoprotective and repair functions. Conclusion: Overall, these results suggest that D. versicolor employs miRNA-mediated regulatory networks to support metabolic suppression, maintain essential signaling, and prevent damage during prolonged cardiac arrest. This work expands our understanding of freeze tolerance at the molecular level and may offer insights into biomedical strategies for cryopreservation and ischemia–reperfusion injury. Full article

One characteristic of tumor cells is the increased anaerobic metabolism through glycolysis leading to an acidic environment of the tumor. This acidity is linked to tumor progression, invasion and metastasis, besides stimulated survival pathways in the malignant cells. The aim of our analysis is to investigate the role of systemic acid–base parameters such as the pH, bicarbonate, baseexcess and lactate in lung cancer patients. Furthermore, alterations in electrolytes and hemoglobin were investigated regarding their impact on overall survival. Data of 937 non-small-cell lung cancer (NSCLC) patients, who underwent anatomic video-assisted thoracoscopic surgery (VATS) resection, was collected in a prospectively maintained database and analyzed. To minimize confounding effects and due to the retrospective study design, we decided to use data from the first arterial blood gas analysis during surgery and the most recent lab results prior to surgery. We found significant correlations between low systemic bicarbonate (<20 mEq/L) and overall survival (p = 0.006). Hyponatremia (<135 mmol/L) correlated with lower 5-year overall survival (p = 0.004) and decreased disease-free survival (p = 0.017). Hypochloremia (<98 mmol/L) was linked to reduced overall survival (p = 0.003) and hypocalcemia (<1.15 mmol/L) with worse disease-free survival (p = 0.015). Hemoglobin under 12 g/dL for women and 13 g/dL for men was associated with poorer outcomes (p < 0.001). Other acid–base parameters such as the pH (p = 0.563), baseexcess (BE) (p = 0.290) and lactate (p = 0.527) did not show significant differences in overall or disease-free (pH: p = 0.130; BE: p = 0.148; lactate: p = 0.418) survival. Systemic bicarbonate, sodium, calcium, chloride and hemoglobin levels were found as prognostic markers and possible therapeutic targets to improve overall survival. Further investigations are necessary to develop therapeutic strategies. Full article

We previously demonstrated that the activation of FGFR signaling in GIST may be a mechanism of GIST resistance to imatinib mesylate (IM). We show here that IM-resistant GIST cells lacking secondary KIT mutations overexpress claudin-1 on both transcriptional and translational levels. In contrast, a knockdown of CLDN1 or inhibition of its activity by PDS-0330 effectively restored GIST’s sensitivity to IM both in vitro and in vivo. This was evidenced by the increased expression of apoptotic markers (e.g., cleaved PARP and caspase-3) and the decreased proliferation rate of IM-resistant GIST T-1R cells treated with a combination of IM and PDS-0330 (or siRNA CLDN1). In concordance with these findings, a significant synergy was observed between IM and PDS-0330 in GIST T-1R cells. Importantly, decreased tumor size and weight were observed in IM-resistant GIST xenografts treated with a combination of IM and PDS-0330. Furthermore, the combined treatment of IM-resistant tumors induced an increase in intratumoral apoptosis and other changes, as defined by the histopathologic response rate. Based on the co-immunoprecipitation and immunofluorescence microscopy data, we also demonstrated the strong interaction pattern between CLDN1 and FGFR2. Of note, the inhibition or knockdown of CLDN1 effectively decreased the phosphorylation of FGFR2 and FRS-2, a well-known FGFR adaptor protein, thereby illustrating CLDN1’s ability to regulate FGFR-signaling and thereby promote FGFR-mediated survival in KIT-inhibited GIST. Consequently, CLDN1 inhibition in GIST effectively disrupted the FGFR-mediated pathway and re-sensitized tumor cells to IM. In concordance with these data, molecular profiling of CLDN1-inhibited GIST T-1R cells illustrated a significant decrease in the majority of FGFR transcripts, including FGFR2, 3, and 4. Additionally, several FGFR ligands (e.g., FGF14, -19, and -23) were also down-regulated in PDS-0330-treated GIST. Notably, exogenous FGF-2 increased CLDN1 expression in a time-dependent manner. In contrast, pan-FGFR inhibitors effectively reduced CLDN1 levels in IM-resistant GIST T-1R cells, thereby illustrating a cross-talk between CLDN1- and FGFR-mediated pathways in IM-resistant GIST. Based on subcellular fractionation and immunofluorescence microscopy data, we also observed partial relocalization of CLDN1 into the cytoplasm in IM-resistant GIST. Notably, PDS-0330 effectively abrogated this relocalization, suggesting that changes in CLDN1 subcellular distribution might also impact GIST resistance to IM. Lastly, based on our small cohort clinical study (n = 24), we observed the increased expression of CLDN1 in most “high-risk” primary GIST known to be associated with poor prognosis and aggressive behavior, thereby illustrating the prognostic value of increased CLDN1 expression in GIST and providing a further rationale to evaluate the effectiveness of CLDN1 inhibition for GIST therapy. Full article