VDAC1 protein derived from extracellular vesicles promotes paclitaxel resistance in gastric cancer through autophagy and mitophagy

Paclitaxel (PTX), a conventional second-line therapeutic agent for advanced gastric cancer (GC), exhibits compromised clinical efficacy due to acquired chemoresistance in patients, the molecular mechanisms of which remain poorly elucidated. This study aimed to investigate the therapeutic potential of targeting extracellular vesicle (EV) protein in reversing PTX resistance in GC cells and to delineate the underlying molecular pathways involved.

Proteomic profiling was used to identify differentially expressed EV proteins in PTX-resistant GC cells. EVs were isolated via size exclusion chromatography (SEC) and characterized using transmission electron microscopy (TEM), nano-flow cytometry (nano-FCM), and western blot analysis. In vivo functional validation was performed in xenograft tumor models by injecting EV proteins into nude mice via the tail vein (6 groups, n = 4). EVs derived from 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS)-treated cells were administered to tumor-bearing nude mouse model (4 groups, n = 5) to determine the impact of EV-derived voltage-dependent anion channel protein 1 (VDAC1) on PTX resistance. In addition, VDAC1 protein expression was evaluated using immunohistochemical (IHC) assays in 34 clinical specimens from PTX-resistant patients.

Proteomic analyses demonstrated a marked upregulation of VDAC1 in EVs secreted by PTX-resistant GC cells. Functional studies revealed that intercellular transfer of EV-derived VDAC1 directly conferred PTX resistance to drug-sensitive cancer cells. Gene set enrichment analysis (GSEA) and adenosine triphosphate (ATP) functional assay further elucidated that VDAC1-mediated chemoresistance was mechanistically linked to the activation of adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) signaling and concomitant suppression of the mammalian target of rapamycin – p70 ribosomal protein S6 kinase (mTOR-p70S6K) pathway. In vivo validation confirmed that systemic delivery of EV-derived VDAC1 significantly reduced PTX sensitivity in GC tumors. Furthermore, DIDS inhibited the expression of the VDAC1 protein in EVs, thereby reducing PTX resistance in vivo and in vitro. IHC analysis revealed that VDAC1 expression was significantly higher in GC patients with PTX resistance compared to PTX-sensitive patients.

The findings herein underscore the pivotal role of EV-derived VDAC1 in driving PTX resistance in GC through dual modulation of autophagy and mitophagy, mediated by the AMPK/mTOR signaling axis. Targeting EV-derived VDAC1 has emerged as a promising therapeutic strategy to counteract chemoresistance, providing a novel avenue for improving GC treatment outcomes.