SIRT3 regulates mitochondrial metabolism through deacetylation of SLC25A6 to impact gastric cancer progression and drug resistance

Gastric cancer (GC) remains a leading cause of cancer-related mortality worldwide, largely due to late diagnosis, rapid progression, and the development of chemoresistance. Mitochondrial metabolic reprogramming has emerged as a critical driver of tumor progression and drug resistance. Sirtuin-3 (SIRT3), a mitochondrial NAD⁺ -dependent deacetylase, plays a context-dependent role in cancer biology; however, its function and underlying mechanism in GC progression and cisplatin (DDP) resistance remain unclear. This study aimed to explore the biological role and molecular mechanism of SIRT3 in GC.

SIRT3 expression and prognostic value were analyzed using The Cancer Genome Atlas (TCGA) database and validated in human GC tissues by qRT-PCR, Western blotting, and immunohistochemistry. Knockdown and overexpression models of SIRT3 were established in AGS and HGC27 GC cell lines. Cell proliferation, migration, invasion, and apoptosis were assessed using CCK-8, colony formation, Transwell, wound-healing, and flow cytometry assays. Cisplatin-resistant GC cell lines and nude mouse xenograft models were established to evaluate chemosensitivity in vitro and in vivo. Transcriptome sequencing (RNA-seq), co-immunoprecipitation, acetylation assays, and cycloheximide chase assays were performed to identify downstream or upstream targets and mechanisms of SIRT3. Rescue experiments were conducted to confirm the dependency of SIRT3 and differentially expressed genes.

SIRT3 expression was significantly upregulated in GC tissues and was associated with poor overall survival. SIRT3 knockdown markedly inhibited GC cell proliferation, invasion, migration, epithelial–mesenchymal transition (EMT), and tumorigenesis, while promoting apoptosis both in vitro and in vivo. Conversely, SIRT3 overexpression enhanced malignant phenotypes. SIRT3 was significantly overexpressed in cisplatin-resistant GC tissues and cell lines, and its upregulation conferred resistance to DDP, whereas SIRT3 silencing sensitized GC cells to DDP in vitro and in xenograft models. RNA-seq identified SLC25A6 as a key downstream target of SIRT3. Mechanistically, SIRT3 directly interacted with SLC25A6 (ANT3/AAC3) and reduced its acetylation level, thereby enhancing its protein stability. SLC25A6 silencing phenocopied the effects of SIRT3 knockdown, and rescue experiments confirmed that the oncogenic and chemoresistant functions of SIRT3 were dependent on ANT3.

SIRT3 promotes GC progression and chemoresistance by deacetylating and stabilizing the mitochondrial ADP/ATP translocator SLC25A6 (ANT3), thereby enhancing mitochondrial metabolic activity. The SIRT3–ANT3 axis represents a novel molecular mechanism driving GC malignancy and chemoresistance and may serve as a promising therapeutic target for improving treatment efficacy in GC.