Search Results (2,559)

Background: Acquired tolerance to temozolomide (TMZ) remains one of the main obstacles to enduring therapeutic success in glioblastoma (GBM). While tumor-derived extracellular vesicles are known to orchestrate therapy evasion by horizontally transferring molecules across the tumor microenvironment, the precise regulatory roles of specific exosomal circular RNAs (circRNAs) in establishing this refractory state require further elucidation. Methods: The expression of circ_0050688 in TMZ-resistant GBM clinical tissues and cell lines was evaluated. Exosomes derived from resistant cells were isolated and confirmed via transmission electron microscopy (TEM) and marker analysis. PKH67 fluorescent tracking was utilized to visually demonstrate exosome internalization by sensitive recipient cells. Biological functions, including the expression of the multidrug resistance protein P-glycoprotein (P-gp) and the proliferation marker Ki-67, were evaluated. The competing endogenous RNA mechanism was validated using RNA FISH, dual-luciferase reporters, and functional rescue experiments. In vivo efficacy was determined using subcutaneous xenograft mouse models. Results: Clinical and in vitro analyses revealed that circ_0050688 is upregulated in TMZ-refractory GBM, predicting adverse patient survival. Through PKH67-based tracing, we confirmed that resistant cells actively secrete circ_0050688-enriched exosomes, which are subsequently engulfed by drug-sensitive bystander cells. This vesicular transfer directly instigates a chemoresistant and highly proliferative phenotype, marked by elevated P-gp and Ki-67 levels. At the molecular level, circ_0050688 operates as a molecular decoy for miR-508-5p, thereby preventing the suppression of its downstream target, MDM2. Functionally, circ_0050688 depletion eradicated these aggressive traits and restored TMZ vulnerability across both cellular and murine xenograft models. Furthermore, rescue assays confirmed that this circ_0050688-driven chemoresistance is fundamentally dependent on the miR-508-5p/MDM2 signaling axis. Conclusions: Current data uncover an intercellular signaling network driven by vesicular circ_0050688, which functions as a mobile oncogene to reshape the TMZ-refractory microenvironment. Targeting this exosomal circ_0050688/miR-508-5p/MDM2 network to suppress P-gp and Ki-67 expression represents a highly promising therapeutic strategy for refractory GBM. Full article

Gastric cancer (GC) remains a leading cause of cancer-related mortality worldwide, with treatment outcomes often severely constrained by the emergence of chemoresistance. Ferroptosis, a regulated, iron-dependent form of cell death driven by lethal lipid peroxidation, is a vulnerability that cancer cells actively evade to survive. Its dysregulation has been increasingly linked to therapeutic resistance across multiple malignancies, including GC. Dysregulation of the cystine–glutathione–GPX4 antioxidant system, iron metabolism, and lipid remodeling allows tumor cells to escape ferroptosis, but targeting ferroptosis represents a promising strategy to overcome therapeutic resistance and restore sensitivity to cancer treatments. This review discusses the molecular regulation of ferroptosis, its contribution to chemoresistance, and translational strategies to exploit ferroptosis in cancer therapy. Full article

Background: Platinum-based chemotherapy is the frontline treatment for high-grade serous ovarian cancer (HGSOC); however, the development of therapy resistance greatly limits clinical response. Increasing evidence suggests that platinum agent-driven metabolic programming, particularly within redox-associated pathways, may contribute to chemoresistance. Methods: A syngeneic pair of patient-derived HGSOC cell lines representing cisplatin-sensitive (SE) and cisplatin-resistant (CR) states were evaluated using a multi-omics approach. Differential metabolite abundance and gene expression were assessed, followed by gene set and pathway enrichment analyses to identify coordinated metabolic shifts. In silico analysis of an additional sensitive and resistant HGSOC cell line validated the glutathione pathway upregulation seen in the patient-derived model. The functional contribution of the glutathione pathway on cisplatin resistance was evaluated following glutathione inhibition. Results: Chronic cisplatin exposure induced extensive metabolic rewiring in CR cells, characterized by enrichment of glutathione metabolism at both the metabolite and gene levels. Increased reduced glutathione was observed alongside upregulation of key enzymes involved in its de novo biosynthesis, recycling, and utilization, consistent with enhanced detoxification capacity relating to cisplatin-induced oxidative stress. Additionally, taurine was highly enriched, further highlighting a metabolic shift towards enhanced antioxidant mechanisms. CR cells also demonstrated an increase in NADPH-generating pathways, including amino acid metabolism and fatty acid β oxidation, to support redox balance and biosynthetic demands of increased glutathione metabolism. Transcriptional remodeling of the γ-glutamyl cycle further indicated a shift toward increased glutathione turnover, suggesting that the coordinated changes seen may define a metabolic state enhanced in oxidative stress tolerance and therapeutic resistance. These transcriptional changes were also seen in another model of platinum sensitivity/resistance, indicating a conserved response associated with platinum-induced resistance. Finally, concurrent cisplatin treatment and glutathione inhibition significantly increased sensitivity within the CR cells. Conclusions: These findings suggest that cisplatin-resistant cells, previously exposed to a platinum-based agent, may undergo distinct metabolic rewiring towards antioxidant pathways to survive chronic chemotherapeutic stress. Targeting components of these systems may represent a viable strategy to overcome platinum resistance and improve therapeutic outcomes. Full article

Lactylation is an emerging lactate-derived post-translational modification that may link tumour metabolic reprogramming, epigenetic regulation and DNA damage repair. Enhanced glycolysis and lactate accumulation are common in many tumours, and lactate has been reported to induce histone and non-histone lactylation in specific experimental contexts. Recent studies suggest that lactylation is associated with several DNA repair pathways, including base excision repair/single-strand break repair, nucleotide excision repair, homologous recombination and non-homologous end joining, and may contribute to therapy resistance in selected cancer models. Specifically, XRCC1 lactylation has been reported to promote nuclear translocation and repair activity in glioblastoma models; H4K12 lactylation has been linked to PARP inhibitor resistance through RAD23A activation in ovarian cancer models; and BLM lactylation has been associated with enhanced homologous recombination repair in bladder cancer models. Lactylation of NBS1, RAD51 and XLF has also been implicated in DNA repair regulation in specific experimental systems, although some mechanistic links are inferred from pathway activation or functional rescue experiments rather than directly demonstrated across multiple tumour types. These findings suggest that lactylation may modulate DNA repair and therapeutic response in a context-dependent manner. Targeting lactate metabolism, transport and lactylation regulators, including LDHA, MCT1/4, ACAT1, AARS1 and GCN5, or using site-specific lactylation-inhibiting peptides may improve chemotherapy and PARP inhibitor efficacy, but clinical translation remains limited by heterogeneity, metabolic plasticity, toxicity and insufficient validation. Full article

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive subtype of ALL characterized by unfavorable clinical outcomes. Despite significant progress in deciphering the genetic and epigenetic landscapes of T-ALL, the underlying molecular mechanisms, particularly in non-early T-cell precursor (non-ETP) T-ALL, remain incompletely understood. In this study, functional assays were performed using three well-characterized non-ETP T-ALL cell lines. In vivo therapeutic efficacy was evaluated using non-ETP T-ALL xenograft models. Transcriptomic profiling was performed by RNA sequencing (RNA-seq) followed by bioinformatic analysis. Publicly available clinical datasets from T-ALL patients were mined to analyze survival outcomes. We found that activation of CD40 ligand (CD40LG) or CD28 accelerates cell-cycle progression and enhances the migratory capacity of non-ETP T-ALL cells, with CD40LG uniquely upregulating CXCR4 to mediate bone marrow tropism. Further RNA-seq and functional validation identified Rho GTPase signaling, specifically RhoA/Rac1/Rac2, as a pivotal downstream effector of CD40LG/CD28, leading to therapeutic resistance to PI3K inhibition. Pharmacological blocking RhoA or Rac1 using small-molecule compounds not only induces remarkable cytotoxicity but also sensitizes resistant cells to PI3K inhibitors, both in vitro and in vivo. Clinically, elevated expression of CD40LG, CD28, RHOA, or RAC2 correlates with poor prognosis in non-ETP T-ALL patients. These findings uncover a novel CD40LG/CD28-Rho GTPase axis as a key driver of pathogenesis and a potential therapeutic vulnerability in non-ETP T-ALL, providing a new target for precision intervention and a promising strategy to overcome therapeutic resistance. Full article

Background/Objectives: Aldo–keto reductase isoforms AKR1C1–3 and 17β-hydroxysteroid dehydrogenase 1 and 2 (17β-HSD1 and 17β-HSD2) are key enzymes in steroid metabolism and validated targets in hormone-dependent cancers. Methods: In this study, Δ¹⁵- and 15β-substituted estrone derivatives were evaluated as inhibitors of AKR1C1–3 and 17β-HSD1 using enzymatic assays, cell viability assaysand computational modeling. Cellular uptake of the fluorescent estrone-based inhibitor was investigated using confocal microscopy. Results: The Δ¹⁵-estrone derivative showed potent and selective inhibition of 17β-HSD1 in the low nanomolar range, while 15β-O-propargyl and 15β-azide derivatives exhibited dual inhibitory activity against 17β-HSD1 and AKR1C2. The Δ¹⁵- and 15β-azide derivatives reduced cell viability in hormone-dependent breast, endometrial, and ovarian cancer cell lines in the sub- to low-micromolar range. A BODIPY-labeled 15β-O-propargyl analogue retained submicromolar inhibitory potency toward 17β-HSD1, representing the first fluorescent estrane-based inhibitor with preserved biological activity. Confocal microscopy confirmed efficient cellular uptake and predominant cytosolic localization in MCF-7 cells. Conclusions: These findings identify Δ¹⁵- and 15β-modified estrone derivatives as promising single- and dual-target inhibitors and introduce a fluorescent probe suitable for investigating intracellular steroid metabolism in hormone-dependent malignancies. Full article

Drug resistance remains a significant barrier to achieving durable treatment responses. Traditionally, resistance has been attributed to genetic alterations and clonal selection. However, accumulating evidence suggests that early adaptation to therapy is often mediated by non-genetic state transitions. In this review, we propose a conceptual framework in which resistance emerges through therapy-driven molecular evolution in bladder cancer, characterized by three interconnected axes: non-genetic plasticity, metabolic reorganization, and tumor microenvironment remodeling. Using the Gemcitabine-Resistant Cell (GRC) model as a temporal reference system, we describe a stepwise transition from drug-sensitive states dominated by proliferation to survival-optimized resistant states through a growth–survival trade-off. Early adaptive phases are marked by the attenuation of cell-cycle and glycolytic programs, increased epigenetic flexibility, and metabolic rewiring involving mitochondrial and lipid-associated pathways. Later phases involve the reinforcement of resistance through extracellular matrix remodeling, developmental and stress-response signaling, and immunometabolic interactions within the tumor microenvironment, including adenosine- and lipid-associated mediators. Projecting the GRC score onto a clinical bladder cancer cohort further suggests that these evolutionary patterns may also be reflected in patient tumors. Overall, this framework supports a temporally structured view of chemoresistance and highlights opportunities to therapeutically target transitional adaptive states before resistance becomes stabilized. Full article

Curcumin, a natural polyphenolic compound derived from turmeric, exhibits broad-spectrum anticancer activities, but its ability to induce pyroptosis in osteosarcoma remains unknown. Osteosarcoma is the most common primary malignant bone tumor in children and adolescents, and novel therapeutic strategies are urgently needed to overcome osteosarcoma chemoresistance. Aim: This study aimed to investigate whether curcumin induces pyroptosis-associated molecular changes in human osteosarcoma cells and to explore the underlying molecular mechanisms, focusing on the ROS/NLRP3/CASPASE-1/GSDMD axis and the PI3K/AKT signaling pathway. Methods: Human osteosarcoma U2OS and MG63 cells were treated with curcumin (20–40 μmol·L⁻¹ for 24 h). Cell viability was assessed by CCK-8 assay. Pyroptotic morphology was observed by scanning electron microscopy. Lactate dehydrogenase (LDH) release was measured colorimetrically, and IL-1β/IL-18 secretion was quantified by ELISA. Mitochondrial membrane potential (ΔΨm) and intracellular reactive oxygen species (ROS) levels were analyzed by flow cytometry. Protein expression levels of NLRP3, cleaved CASPASE-1, GSDMD-N, PI3K, AKT, p-AKT, Bax, Bcl-2 and cleaved CASPASE-3 were detected by Western blotting. Pharmacological validation was performed using the pan-caspase inhibitor Z-VAD-FMK. Results: Curcumin significantly inhibited the proliferation of U2OS and MG63 cells in a dose- and time-dependent manner. Scanning electron microscopy revealed characteristic pyroptotic features including cell swelling, membrane pore formation, and rupture. Curcumin treatment markedly increased LDH release and elevated IL-1β/IL-18 secretion. Mechanistically, curcumin induced mitochondrial membrane depolarization and ROS accumulation, upregulated NLRP3, cleaved CASPASE-1, and GSDMD-N expression, and concomitantly reduced PI3K/AKT pathway activity. Additionally, curcumin upregulated pro-apoptotic Bax, downregulated anti-apoptotic Bcl-2, and activated cleaved CASPASE-3. The pan-caspase inhibitor Z-VAD-FMK partially reversed curcumin-induced cytotoxicity, confirming that caspase-dependent apoptosis contributes to the overall anticancer effect. Conclusions: This study provides evidence that curcumin induces both apoptosis and pyroptosis-associated molecular changes in human osteosarcoma cells. The pyroptotic effect involves the ROS/NLRP3/CASPASE-1/GSDMD axis, accompanied by PI3K/AKT suppression, while caspase-dependent apoptosis also plays an important role. These findings uncover a previously unreported mechanism of curcumin’s anti-osteosarcoma activity and suggest that targeting multiple cell death pathways may represent a promising strategy to overcome apoptosis resistance in osteosarcoma. Full article

Glioblastoma multiforme (GBM) is the most aggressive brain tumor in adults. Necrosis, and by inference hypoxia, is a pathognomonic feature of GBM tumors, where hypoxia significantly contributes to chemoresistance, leading to local treatment failure and disease progression. Although temozolomide (TMZ) is the main treatment option, 60–75% of GBM patients do not benefit from it. This study aimed to evaluate the therapeutic potential of Tetrandrine (TET) in combination with or compared to TMZ in treating GBM cells (M010b and U87) under both normoxic and hypoxic conditions. The therapeutic potential was assessed using qRT-PCR, MTT assay, combination index analysis, flow cytometry for apoptosis and cell cycle analysis, scratch assay, gelatin zymography, measurement of mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS) production, and molecular docking. Under both normoxic and hypoxic conditions, TET showed significant cytotoxicity in both cell lines compared to TMZ. A synergistic effect was observed only under normoxia at 2× IC₅₀ concentrations in M010b cells, and at 4× IC₅₀ concentrations in U87 cells. TET significantly increased the sub-G1 cell population and apoptosis compared to TMZ in both cell lines under normoxic and hypoxic conditions, while TMZ induced G2/M arrest in U87 cells under both conditions. TET significantly increased ROS production in both cell lines under normoxia. Under both conditions, ΔΨm was significantly reduced by TET in M010b cells and by TMZ in both cell lines. TET and TMZ significantly reduced pro-MMP-2 levels in M010b cells under both conditions and in U87 cells under normoxia. In conclusion, given the limited therapeutic potential of TMZ, our findings suggest that TET could be a viable alternative treatment option for GBM. Full article

Background/Objectives. Breast cancer is the most frequently diagnosed cancer worldwide, with approximately 15% classified as Triple-Negative Breast Cancer (TNBC). TNBC is characterized by the absence of estrogen receptor (ER) and progesterone receptor (PR), and the lack of HER2 overexpression, limiting use of targeted therapies. Current TNBC treatment relies heavily on chemotherapy, most commonly taxanes including paclitaxel that stabilize microtubules, disrupt chromosome separation and induce apoptosis. TNBCs frequently develop chemoresistance after multiple treatment cycles, highlighting a critical unmet need for novel therapeutic strategies. This study addresses this challenge by targeting salt-inducible kinase 2 (SIK2), which is overexpressed in 85% of TNBCs compared to normal breast tissue. Methodes. In collaboration with Arrien Pharmaceuticals and Greenfire Biologics, we developed ARN-3261/GRN-300, a novel orally bioavailable SIK2 inhibitor and evaluated its ability to sensitize TNBC cells to paclitaxel in vitro and in vivo. Results. GRN-300 demonstrated strong synergy with paclitaxel in all eight TNBC cell lines tested, as indicated by favorable combination indices. In xenograft models, the combination therapy significantly enhanced tumor growth inhibition and prolonged survival compared to either agent alone. Mechanistic studies showed that GRN-300 disrupts the anaphase-promoting complex/cyclosome (APC/C) pathway by downregulating key mitotic regulators, including CDC27, CDK1, and PLK1, thereby potentiating G2/M cell cycle arrest and apoptosis. Conclusions. Together, these findings establish GRN-300 as a promising therapeutic agent that enhances paclitaxel efficacy through complementary disruption of mitotic regulatory pathways, providing strong preclinical rationale for clinical development in TNBC. Full article

Colorectal cancer (CRC) presents high incidence and mortality, largely due to late diagnosis and the persistence of cancer stem cells (CSCs), which contribute to chemoresistance and poor patient outcomes. TRAIL (TNF-related apoptosis-inducing ligand) is considered a promising therapeutic agent because of its ability to selectively induce apoptosis through DR4/DR5 receptors. Mesenchymal stem cells (MSCs) have been explored as TRAIL delivery vehicles, taking advantage of their tumor-homing capacity and sustained protein expression. However, TRAIL monotherapy has shown limited efficacy, prompting research into strategies to enhance its pro-apoptotic effect, including its combination with chemotherapeutics that upregulate TRAIL receptors. Methods: We evaluated the effect of irinotecan (IRINO) in Caco-2 cells and primary CRC cultures. In addition, we analyzed the cytotoxic activity of sTRAIL-MSCs and its impact on CSC markers, both alone and in combination with IRINO in Caco-2 cells. Results: Caco-2 cells and 87.5% of primary cultures were resistant to IRINO. sTRAIL-MSCs induced higher cell death (50–80%) at ratios of 1:3 and 1:6, while its combination with IRINO achieved 50–60%. Additionally, sTRAIL-MSCs reduced CSC marker expression at 24 and 48 h. Conclusions: IRINO did not enhance the cytotoxicity of sTRAIL-MSC, but it did enhance downregulated markers such as KRT-18, CD44v6, and EpCAM, and it represents a promising therapeutic strategy against CRC. Full article

Germline loss-of-function mutations in BRCA1 and BRCA2 markedly increase susceptibility to breast, ovarian, and other cancers. Mechanistically, BRCA2 facilitates RAD51 recruitment to sites of DNA damage, whereas BRCA1 regulates homologous recombination repair (HRR) through double-strand break resection and broader DNA damage response signaling. These insights underpin targeted therapies such as poly (ADP-ribose) polymerase inhibitors (PARPis), which induce synthetic lethality in homologous recombination-deficient tumors. Clinically, PARPis have demonstrated significant benefit in BRCA1/2-mutated breast, ovarian, pancreatic, and prostate cancers. However, resistance remains a major obstacle, with secondary intragenic BRCA1/2 mutations restoring partial protein function representing a prominent mechanism. Despite therapeutic advances, critical gaps persist in understanding how specific BRCA1/2 domains and residual protein activities contribute to tumorigenesis and treatment response. In this review, we summarize the structural and functional domains of BRCA1/2, their pathogenic mutation profiles, and therapeutic strategies targeting BRCA1/2-deficient cancers. Despite therapeutic advances, critical gaps persist in understanding how specific BRCA1/2 domains and residual protein activities contribute to tumorigenesis and treatment response. This review emphasizes the need for functional studies of BRCA1/2 variants to refine risk prediction and develop mutation-tailored therapies. Full article

Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy with a poor prognosis, largely due to therapeutic resistance and the limited availability of effective targeted therapies. Aloperine (ALO), a natural alkaloid derived from Sophora alopecuroides L., exhibits anti-cancer properties in various tumor types; however, its therapeutic potential and underlying mechanism in ESCC remain unclear. Here, we report that ALO inhibited ESCC cell proliferation and colony formation in a dose- and time-dependent manner and induced caspase-dependent apoptosis, accompanied by loss of mitochondrial membrane potential and PARP1 cleavage. Mechanistically, ALO significantly suppressed inflammatory pathways, with IL-6 identified as a critical downregulated target. ALO inhibited IL-6 production by targeting the AP-1 transcription factor complex, as evidenced by reduced cFOS expression and suppressed cJUN phosphorylation. Consequently, ALO inhibited downstream IL-6/JAK-STAT3 signaling. Functionally, exogenous IL-6 rescued ALO-induced loss of cell viability. Notably, the combination of ALO with cisplatin exerted synergistic antitumor effects. In a syngeneic mice model, the combination therapy significantly reduced tumor growth and Ki67 expression while inducing apoptosis, as shown by increased TUNEL staining and cleaved caspase-3 expression, and further suppressing the IL-6/STAT3 axis compared with either monotherapy. Together, these findings demonstrate that ALO exerts potent anti-ESCC activity by targeting the AP-1/IL-6/STAT3 signaling axis. The synergistic efficacy of ALO with cisplatin highlights its potential as a promising therapeutic agent to overcome chemoresistance and improve outcomes in ESCC patients. Full article

Background/Objectives: RNA polymerase II is a multifunctional complex that is critical for gene regulation and environmental responses. Its POLR2I subunit in humans is associated with various pathologies, including cancer chemoresistance. However, much of our understanding of how POLR2I functions is inferred from studies of its homologs in yeasts called Rpb9. Here, we endogenously humanized the rpb9 gene of the fission yeast Schizosaccharomyces pombe to examine the functional capabilities of POLR2I. Methods: We edited the genomic rpb9 locus in S. pombe so that it encodes the human POLR2I protein, and investigated functional and structural conservation. Results: With our humanized yeast system, we find widespread functional complementation by human POLR2I of S. pombe rpb9 roles in yeast growth, chronological aging, and stress responses. We also find that POLR2I complements novel roles for yeast rpb9 in facultative heterochromatin assembly, resistance against the chemotherapy 5-fluorouracil, and resistance against the fungicide thiabendazole. In contrast, we find that POLR2I cannot complement the role of rpb9 in resistance against the transcription elongation inhibitor 6-azauracil (6-AU) in our system. Interestingly, POLR2I could complement 6-AU resistance if ectopically expressed. Lastly, we observe extensive structural homology between Rpb9 and POLR2I proteins. Conclusions: Our study establishes an endogenous cross-species gene complementation strategy that uncovers both conserved and rewired functions of fission yeast rpb9 and its human homolog, POLR2I. In addition to validating conserved roles, we also identified conservation of previously unrecognized roles of rpb9 in heterochromatin formation and chemoresistance. Full article

Background: Glioblastoma (GBM) remains a lethal malignancy due to temozolomide (TMZ) resistance and limited drug penetration across the blood–brain barrier, largely driven by hyperactive DNA damage repair mechanisms such as poly (ADP-ribose) polymerase (PARP). To address these challenges, we developed folic acid-targeted PLGA–zein hybrid core–shell nanoparticles for the codelivery of the alkylating agent TMZ and the natural PARP inhibitor Ellagic acid (FA-TMZ/EA-PZ-CS NPs), thereby enabling simultaneous enhancement of drug delivery and suppression of chemoresistance pathways. Methods and Results: The dual-drug nanoplatform was fabricated using a double-emulsion solvent evaporation method and functionalized via EDC/NHS-mediated folic acid conjugation to promote receptor-mediated uptake. Physicochemical characterisation confirmed uniform spherical morphology, high colloidal stability, efficient drug encapsulation, and sustained biphasic drug release consistent with a core–shell diffusion mechanism. In LN229 glioblastoma cells, folic acid conjugation significantly enhanced cellular internalisation and cytotoxic efficacy compared to free drugs and non-targeted nanoparticles. Combination index analysis revealed strong synergism between TMZ and ellagic acid, resulting in markedly reduced IC₅₀ values. Mechanistic studies demonstrated apoptosis induction, increased DNA damage, inhibition of cell migration at sub-cytotoxic concentrations, and downregulation of PARP gene expression. Conclusion: Overall, this study establishes a targeted core–shell nanotherapeutic strategy that integrates chemotherapy with DNA repair inhibition to overcome TMZ resistance, offering a mechanistically sound strategy that serves as a foundational framework for future translational research. Full article