Targeted modulation of IGFBP5/IGF1, THPO, and P38 MAPK signaling are potent therapeutic strategies generalizable for mitochondrial respiratory chain disease and osteosarcoma

PGAM5-mediated VDAC1 oligomerization Facilitates Ponatinib-Induced Cardiotoxicity via Disrupting the Mitophagy-Mitochondrial unfolded protein response Synergistic Defense Crosstalk.

OBJECTIVES Ponatinib is an effective tyrosine kinase inhibitor for chronic myeloid leukemia with the T315I mutation, but its clinical use is often limited by serious cardiovascular toxicity. Although mitochondrial dysfunction has been implicated in this process, the upstream stress-sensing mechanism that converts ponatinib exposure into collapse of mitochondrial quality control (MQC) remains poorly defined. We therefore investigated whether the PGAM5/VDAC1 axis mediates ponatinib-induced cardiac injury by coordinately disrupting mitophagy and the mitochondrial unfolded protein response (UPRmt). METHODS Cardiomyocyte-specific PGAM5 knockout mice (Pgam5_cko) and littermate controls (Pgam5_f/f) were fed a high-fat diet and then exposed to ponatinib. Cardiac function and adult cardiomyocyte contractility were assessed by echocardiography and IonOptix analysis. Single-cell RNA sequencing, in vivo genetic loss-of-function models, and HL-1 cells with stable Pgam5 knockdown were used to define the underlying mechanism. MQC status, including mitophagy and UPRmt, was evaluated by fluorescence imaging, RT-qPCR, western blotting, and biochemical assays. RESULTS Ponatinib markedly increased PGAM5 expression in the heart and induced contractile dysfunction, inflammatory activation, and cardiomyocyte apoptosis. These changes were substantially attenuated in Pgam5_cko mice. Mechanistically, ponatinib promoted pathological oligomerization of the outer mitochondrial membrane protein VDAC1 in a PGAM5-dependent manner. This event was accompanied by simultaneous suppression of PINK1/Parkin-related mitophagy and the UPRmt program, resulting in mitochondrial fragmentation, oxidative stress, and impaired bioenergetic function. At the functional level, loss of PGAM5 restored MQC and preserved cardiac performance under ponatinib stress. Importantly, forced VDAC1 oligomerization with arsenic trioxide largely abolished the protective effects of PGAM5 deficiency, supporting VDAC1 oligomerization as a critical downstream event in this pathway. CONCLUSION These findings identify the PGAM5/VDAC1 axis as a key mechanism linking ponatinib stress to coordinated failure of MQC in the heart. By simultaneously disabling mitophagy and UPRmt, this pathway drives mitochondrial dysfunction and cardiac injury. Targeting PGAM5-dependent VDAC1 oligomerization may therefore represent a potential strategy for limiting ponatinib-associated cardiotoxicity.

Abstract A025: Dual NR4A1/2 ligands inhibit PAX3-FOXO1 and promote ferroptosis in Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and adolescents, with poor outcomes in metastatic and treatment-resistant disease. The alveolar subtype is frequently driven by the PAX3-FOXO1 fusion oncoprotein, which promotes tumor progression and therapeutic resistance. Ferroptosis, an iron-dependent regulated cell death process characterized by lipid peroxidation and oxidative stress, represents a promising therapeutic vulnerability in RMS. This study investigated whether bis-indole-derived dual NR4A1/2 ligands (C-DIM compounds) suppress PAX3-FOXO1 signaling and induce ferroptosis through regulation of iron metabolism and antioxidant defense pathways in RMS cells. Human RMS cell lines (RD and RH30) were treated with C-DIM compounds. Cell viability was assessed using XTT assays. Intracellular ROS and lipid peroxidation were measured using H2DCFDA and BODIPY™ 581/591 staining, and oxidative damage was quantified by malondialdehyde (MDA) assays. Expression of ferroptosis-related markers, including CD71, GPX4, SLC7A11, and FSP1, was analyzed by qPCR and Western blotting. NR4A1, NR4A2, and Sp1, Sp4 were silenced using siRNA to determine their functional roles. C-DIM treatment significantly reduced RMS cell viability and suppressed PAX3-FOXO1 expression and downstream oncogenic signaling. These effects were associated with increased ROS production, lipid peroxidation, and MDA accumulation, confirming ferroptosis induction. Mechanistically, dual NR4A1/2 ligands triggered early and dose-dependent induction of CD71, suggesting enhanced iron uptake as an initiating event. In parallel, key ferroptosis-protective regulators, including GPX4, SLC7A11, and FSP1, were significantly downregulated. Knockdown of NR4A1/2 or Sp1/4 down regulates GPX4, SLC7A11, and FSP1and reduced ferroptotic cell death, indicating a critical role for the NR4A1/2–Sp1/4 axis. Dual NR4A1/2 ligands suppress PAX3-FOXO1 signaling and promote ferroptosis through coordinated modulation of iron uptake and antioxidant defense pathways. Early CD71 induction combined with suppression of GPX4, SLC7A11, and FSP1 highlights a multi-level ferroptotic mechanism in RMS. Further studies are needed to elucidate the precise regulatory mechanisms underlying the suppression of ferroptosis-related genes. Targeting NR4A1/2 may represent a promising therapeutic strategy for overcoming resistance in rhabdomyosarcoma. Arafat Rahman Oany, Stephen Safe. Dual NR4A1/2 ligands inhibit PAX3-FOXO1 and promote ferroptosis in Rhabdomyosarcoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Breaking Barriers in the Fight against Rare Cancers; 2026 Jul 18-20; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(14_Suppl):Abstract nr A025.

miR-27b-3p Exacerbates VCD-Induced KGN Cell Injury by Targeting PAPPA to Suppress IGF-1 Release and Inhibit the PI3K/AKT Pathway

Background/Objectives: While currently termed premature ovarian insufficiency (POI), premature ovarian failure (POF) remains a prominent driver of female infertility with a molecular pathogenesis that is still lacking comprehensive clarification. In in vitro studies, the pathology of POI is commonly simulated through a well-characterized model involving VCD (4-vinylcyclohexene diepoxide)-mediated cytotoxicity within KGN-derived human granulosa cells. However, the key regulatory molecular networks involved in this process are still poorly characterized. Although microRNAs (miRNAs) have emerged as critical regulators in ovarian function decline, the specific role and underlying mechanism of miR-27b-3p in POI remain elusive. Methods: A VCD-induced KGN cell injury model was established by treating cells with 1.0 mM VCD for 24 h. Cell viability, apoptosis rate, and miR-27b-3p expression were assessed by CCK-8 assay, flow cytometry, and RT-qPCR, respectively. Overexpression and targeted suppression of miR-27b-3p were achieved by introducing its specific mimics and inhibitors, respectively. Target identification was conducted via bioinformatic prediction, EdU incorporation, Western blot, and dual-luciferase reporter assays. Functional rescue experiments were carried out by co-transfection with a PAPPA-overexpressing plasmid (oe-PAPPA). IGF-1 secretion was quantified by ELISA, and phosphorylation of IGF1R and AKT was analyzed by Western blot to determine whether miR-27b-3p modulates cellular phenotypes via the PAPPA–IGF-1–PI3K/AKT axis. Exogenous IGF-1 supplementation was further applied to confirm pathway dependence. Results: VCD treatment dose-dependently restrained cellular growth and stimulated apoptotic pathways in KGN cells; paralleling these phenotypic changes, miR-27b-3p abundance was remarkably increased. Ectopic expression of miR-27b-3p exacerbated VCD-induced growth inhibition and apoptosis, whereas its inhibition conferred cytoprotective effects. Through the integration of computational predictions and dual-luciferase reporter systems, PAPPA was definitively established as a direct downstream target of miR-27b-3p. miR-27b-3p negatively regulated both PAPPA mRNA and protein levels, thereby impairing PAPPA-mediated cleavage of IGF-binding proteins (e.g., IGFBP4) and subsequent release of free IGF-1. This led to reduced IGF-1 secretion and significantly diminished phosphorylation of IGF1R and AKT. Remarkably, PAPPA overexpression effectively reversed the detrimental effects of miR-27b-3p, and exogenous IGF-1 supplementation similarly attenuated miR-27b-3p–mediated proliferation arrest and pro-apoptotic phenotypes. Conclusions: This study uncovers a novel pathogenic mechanism whereby miR-27b-3p exacerbates VCD-induced granulosa cell injury by directly targeting PAPPA, suppressing IGF-1 release, and consequently inhibiting the PI3K/AKT pro-survival signaling pathway. A novel perspective on the fundamental basis of POI is established by this research, which further posits therapeutic manipulation of the miR-27b-3p/PAPPA/IGF-1 module as a prospective treatment for disrupted ovarian function.

Dual knockdown of Scn1b and Gsdmd induces an M2-like functional state in macrophages and modulates inflammation and fibrosis in a rat model of acute respiratory distress syndrome

PNPT1-induced mitochondrial dysfunction drives osteoclast activation via post-transcriptional Nrf2 suppression and lipid peroxidation signaling.

BACKGROUND Polynucleotide phosphorylase 1 (PNPT1) functions as a crucial mitochondrial enzyme; nevertheless, its potential genetic correlation with osteoporosis and its specific regulatory impact on osteoclastogenesis remain to be elucidated. METHODS We executed a two-sample Mendelian randomization (MR) strategy to interrogate the causal link connecting PNPT1 expression to osteoporosis risk. For in vivo substantiation, we utilized both an ovariectomized (OVX) murine model and an adeno-associated virus (AAV)-driven overexpression system. Extensive in vitro assays employing RANKL-stimulated RAW264.7 macrophages were conducted to evaluate osteoclast differentiation, mitochondrial dynamics, autophagic flux, and intracellular oxidative stress through molecular and morphological analyses. RESULTS MR evaluations pinpointed genetically predicted elevated PNPT1 expression as a potential genetic risk factor for osteoporosis. In vivo observations revealed a significant surge of PNPT1 within the osteoclast precursors of OVX subjects. In vitro, the ectopic overexpression of PNPT1 significantly enhanced osteoclastogenesis and bone degradation while simultaneously triggering severe mitochondrial depolarization alongside the accumulation of reactive oxygen species (ROS). On the contrary, targeted Pnpt1 silencing markedly suppressed osteoclast maturation. Mechanistic probes demonstrated that PNPT1 disrupted autophagic flux, marked by p62 accumulation. Notably, even with a compensatory transcriptional rise in Nrf2 mRNA, PNPT1 overexpression provoked a marked downregulation of Nrf2 and xCT proteins, suggesting a potent post-transcriptional suppression of the cellular antioxidant shield. This uncoupling invariably precipitated sub-lethal lipid peroxidation that amplifies osteoclastogenic signaling. Concordantly, AAV-mediated systemic PNPT1 amplification aggravated trabecular bone deterioration in vivo. CONCLUSION Guided by our MR findings and validated through our functional models, PNPT1 emerges as a potential genetic risk factor for osteoporosis. By inciting mitochondrial damage, provoking ROS buildup, and decoupling the protective autophagy-Nrf2/xCT axis, PNPT1 promotes osteoclastogenesis, thereby introducing a promising immunopharmacological target for restraining pathological bone resorption.

ATP6AP2 dysregulation as a central hub in DMD pathogenesis: An integrated multi-omics and therapeutic study.

It is demonstrated that TMZ mitigates dystrophic pathology by targeting the ATP6AP2 signaling axis and dampening macrophage-mediated inflammatory responses, highlighting its potential as a novel immunopharmacological therapeutic strategy for DMD.