Ailanthone targets mitophagy-loaded SIRT4 to facilitate the deacetylation of HIF1α, triggering oxidative stress for gastric carcinoma treatment.

[BACKGROUND] Gastric carcinoma poses a major global threat to human health, highlighting an urgent need for effective clinical therapies. Ailanthone (AIL) is the main active component of Ailanthus altissima and has shown antitumour effects in different cancer types, including gastric cancer. However, the molecular mechanisms underlying its anti-gastric cancer activity remain unclear.

[PURPOSE] The research aimed to explore the efficacy and underlying molecular mechanisms of AIL in treating gastric carcinoma.

[METHODS] The anti-proliferative effects of AIL on gastric cancer cells were evaluated using MTT, colony formation, and EdU incorporation assays. Transcriptomics was conducted to explore potential targets and signalling pathways. Western blotting, flow cytometry, single cell gel electrophoresis, glutathione and malondialdehyde assays, immunofluorescence staining, and siRNA transfection were employed to elucidate regulatory mechanisms of AIL on reactive oxygen species (ROS) production and cell apoptosis. Moreover, transmission electron microscopy (TEM), mitochondria isolation, and co-immunoprecipitation (Co-IP) assay were applied to detect mitophagy. Finally, the xenograft mice bearing MGC-803 cells were employed to detect the effects of AIL on tumour growth in vivo.

[RESULTS] AIL significantly suppressed gastric cancer cell proliferation. Transcriptomics analysis revealed that AIL markedly disrupted the oxidative stress pathway, which triggered ROS accumulation-induced apoptosis. TEM results confirmed that AIL specifically inhibited mitophagy, causing mitophagy substrate deacetylase SIRT4 accumulation, which promoted transcription factor hypoxia-inducible factor-1 alpha (HIF1α) deacetylation and reduced its stability. Reduced HIF1α stability decreased antioxidant protein heme oxygenase 1 (HO-1) expression, which boosted ROS levels. SIRT4 knockdown restored HIF1α acetylation. Further, AIL inhibited tumour growth in xenograft mice bearing MGC-803 cells, while exhibiting low toxicity.

[CONCLUSIONS] Our results revealed that AIL targeted mitophagy-loaded SIRT4 to regulate redox homeostasis, inducing mitochondrial dysfunction-mediated cell apoptosis and inhibiting gastric cancer growth. These findings provide strong evidence for the potential clinical use of AIL in gastric cancer treatment.