Acquired resistance to proteasome inhibitors (PIs) remains a major challenge limiting the long-term efficacy of multiple myeloma (MM) therapy, while the metabolic–epigenetic mechanisms underlying PI resistance remain incompletely defined. Using clinical bone marrow specimens, paired parental and PI-resistant MM cell models, xenografts, and integrated lactylome, CUT Tag, and RNA-seq profiling, we investigated the role of lactate-associated lactylation in acquired PI resistance. Bone marrow lactate levels, lactate dehydrogenase (LDH) activity, and global protein lactylation were elevated in relapsed/refractory MM and in PI-resistant cell models. Lactylome profiling revealed extensive lactylation remodeling and identified histone H4K12 lactylation (H4K12la) as a prominent resistance-associated epigenetic mark. Integrative prioritization and functional validation identified EP300 as an upstream regulator of H4K12la; EP300 was upregulated in resistant cells, and its depletion reduced H4K12la and partially restored PI sensitivity. Integration of H4K12la CUT Tag and RNA-seq linked resistance-associated H4K12la remodeling to autophagy/lysosome-related transcriptional programs, with increased H4K12la occupancy at the Cathepsin L (CTSL) promoter accompanied by increased CTSL expression. Pharmacological LDH inhibition with FX-11 reduced H4K12la and CTSL expression. Moreover, combining FX-11 with carfilzomib markedly enhanced antitumor activity in a PI-resistant MM xenograft model without detectable systemic or hematological toxicity during the treatment period. Collectively, these findings define a lactate–EP300–H4K12la–CTSL pathway that contributes to PI resistance and provide a preclinical rationale for combined metabolic and proteasomal inhibition in refractory MM.
Cardiovascular diseases are the leading cause of mortality and disability worldwide. Disulfide-bond oxidized HMGB1 (ds-HMGB1) functions as a core damage-associated molecular pattern that mediates acute myocardial injury. Nevertheless, commercially available HMGB1 reagents exhibit mixed proteoforms, unstable biological activity and low receptor affinity, which greatly hinder mechanistic investigations in this field. This study generated a novel mutant full-length murine ds-HMGB1, systematically dissected its molecular mechanisms underlying aggravated ischemic myocardial injury, and sought to provide a standardized protein reagent and theoretical framework for HMGB1-targeted therapies against myocardial damage. A K184S/K185S mutant HMGB1 plasmid was constructed, and protein purified by three-step chromatography. Structural modeling, mass spectrometry, SPR and PLA were used to analyze conformation, modification and receptor binding kinetics. Hypoxic cardiomyocyte co-culture and mouse myocardial infarction models were established. Flow cytometry, echocardiography, histological staining, qPCR, Western blot and RNA-seq were applied to detect molecular phenotypes and signaling pathways. The K184S/K185S mutation preserved the native overall conformation and functional disulfide bond of HMGB1, while markedly enhancing HMGB1 binding to RAGE and promoting TLR4-MD2 complex assembly. In vitro experiments revealed that mutant ds-HMGB1 either acted directly on cardiomyocytes or synergized hypoxia through endothelial-cardiomyocyte paracrine signaling to induce robust intracellular ROS accumulation, mitochondrial dysfunction and cardiomyocyte apoptosis. In vivo administration expanded myocardial infarct size, impaired cardiac systolic performance and exacerbated inflammatory infiltration in cardiac tissue. Transcriptomic profiling identified 53 core injury genes specifically upregulated by ds-HMGB1 under ischemic stress. The mutant ds-HMGB1 developed in this study addresses the intrinsic drawbacks of commercial HMGB1 preparations. We further identified 53 key myocardial injury genes modulated by ds-HMGB1. This work delivers a standardized experimental reagent and multi-layered mechanistic evidence supporting HMGB1 as a therapeutic target for acute myocardial infarction.
Anthracycline-induced cardiotoxicity (AIC), in which ferroptosis-related cardiomyocyte injury has been implicated, remains a major challenge in oncology. This study investigates the therapeutic potential of an apolipoprotein A1 (ApoA1) mimetic peptide, L-4 F, in epirubicin-induced cardiotoxicity (EIC) in a rat model. Rats received epirubicin (2.5 mg/kg/week, i.p.) for six weeks to establish the EIC model, with or without concurrent ApoA1 mimetic treatment (L-4 F, 1 mg/kg/day). Cardiac function was assessed by echocardiography. Myocardial tissues underwent single-nucleus RNA sequencing (snRNA-seq), RegDiffusion-based gene regulatory network inference, Western blot, immunohistochemistry, and ELISA. Mechanistic studies used H9C2 cardiomyoblasts and CMEC-H9C2 Transwell co-culture systems under EPI exposure, with ApoA1 treatment, endothelial IL-33 knockdown, and Ferrostatin-1 (Fer-1) rescue. Glutathione peroxidase 4 (GPX4) expression, intracellular iron, lipid peroxidation, and cell viability were assessed. ApoA1 treatment alleviated diastolic dysfunction and weight loss and partially improved global longitudinal strain. snRNA-seq revealed substantial transcriptional remodeling in cardiomyocytes. RegDiffusion analysis identified coordinated reprogramming of transcription factor regulons, including Ppara, Fos, Egr1, and Klf4. ApoA1 treatment was associated with an anti-ferroptotic pattern of ferroptosis-related gene expression, with relatively higher Gpx4 and Slc7a11 expression and lower Tfrc expression, consistent with increased GPX4 protein levels. Intercellular communication analysis suggested enhanced IL-33/ST2-mediated endothelial-cardiomyocyte signaling following ApoA1 treatment. In vitro, ApoA1 restored GPX4 expression and reduced iron accumulation under EPI stress; these effects were potentiated in co-culture conditions and attenuated by endothelial IL-33 knockdown. In the rescue model, ApoA1 and Fer-1 partially restored viability and reduced MDA. ApoA1 alone did not significantly lower C11-BODIPY oxidation, whereas the combination gave the most consistent effect. ApoA1 attenuates EIC and is associated with modulation of GPX4-linked ferroptosis-related responses. This protective effect may involve endothelial-cardiomyocyte crosstalk, with endothelial IL-33 signaling acting as a partial contributor. These findings highlight a potential cardioprotective mechanism.
Immune checkpoint inhibitors (ICIs) have reshaped cancer treatment; however, durable clinical benefit remains limited by primary and acquired resistance, frequently associated with T cell dysfunction within an immunosuppressive tumor microenvironment. Beyond their classical role in hemostasis, platelets have emerged as active immune modulators capable of shaping antitumor T cell responses. Accumulating evidence indicates that platelets engage T cells through contact-dependent receptor–ligand interactions, immunomodulatory soluble factors, and the transfer of checkpoint-associated extracellular vesicles, thereby reinforcing dysfunctional T cell states and constraining responses to immune checkpoint blockade. In this review, we synthesize current mechanistic insights into platelet–T cell crosstalk, delineate its differential impact across T cell subsets, and integrate these processes into a broader framework of immune evasion and immunotherapy resistance. We further discuss emerging translational strategies aimed at modulating platelet immune functions, including antiplatelet drug repurposing, selective targeting of platelet–immune interfaces, and metabolic interventions to restore T cell fitness. Collectively, this work reframes platelets as non-canonical immune regulatory nodes and highlights platelet–T cell interactions as a therapeutically actionable layer of immune regulation with implications for improving and personalizing cancer immunotherapy. Platelets act as underappreciated immune regulators that shape T cell function inthe tumor microenvironment Platelet–T cell interactions arise through contact-dependent signaling, solublemediators, and platelet-derived extracellular vesicles Platelet cues can reprogram multiple T cell compartments, with subset- and contextspecificoutcomes This crosstalk may contribute to immune checkpoint inhibitor resistance byreinforcing dysfunctional T cell states Targeting platelet immune functions offers a rationale for combination strategiesalongside immunotherapy
Heart failure (HF) is defined as a condition characterized by abnormalities in the heart's structure or function, which lead to the heart's inability to deliver oxygen to tissues in a timely manner, and it may progress to symptoms such as muscle atrophy of skeletal muscles. Our research primarily focuses on Glycine N-methyltransferase (GNMT), an enzyme that utilizes S-adenosylmethionine (SAM) to catalyze glycine, in order to explore its specific role in HF-induced skeletal muscle atrophy. In this study, an HF rat model induced by abdominal aortic constriction (AAC) and a C2C12 muscle atrophy cell model induced by angiotensin Ⅱ (Ang Ⅱ) were established. Echocardiography, ELISA, and HE staining were used to evaluate the damage of myocardial and gastrocnemius tissues. Immunofluorescence staining was used to assess skeletal muscle atrophy. Western blot, IP, and Co-IP were used to determine the molecular mechanism. In HF rats, the expressions of GNMT and Mitochondrial Fo complex subunit F2 (ATP5J2) were significantly decreased. Overexpression of GNMT/ATP5J2 contributed to alleviate HF-induced skeletal muscle atrophy. GNMT elevated the succinylation level and protein stability of ATP5J2 at lysine 22 (K22) by consuming glycine, and simultaneously reduced its ubiquitination level. Succinylated ATP5J2 improved mitochondrial homeostasis to mitigate HF-induced skeletal muscle atrophy. This study elucidated the function of the GNMT-ATP5J2 axis in HF-induced skeletal muscle atrophy and clarified the underlying molecular mechanism, providing a new theoretical basis for the treatment of HF-induced skeletal muscle atrophy.
