Suppression of DRP1­mediated mitophagy increases the apoptosis of hepatocellular carcinoma cells in the setting of chemotherapy.

The efficacy of chemotherapy for hepatocellular carcinoma (HCC) remains unsatisfactory, primarily due to inherent self­defense mechanisms (e.g., mitophagy and autophagy). In the present study, we aimed to explore the pro­apoptotic effects of targeting mitophagy to potentiate the efficacy of chemotherapy for HCC. HCC cells were subjected to cisplatin, after which cisplatin­induced mitophagy was quantified by immunofluorescence. Mdivi­1, a specific dynamin­related protein 1 (DRP1) inhibitor, was used to study the role of DRP1 in cisplatin­induced HCC mitophagy. The synergistic effect of cisplatin and the DRP1 inhibitor on HCC was assessed in vitro and in vivo. Accordingly, cisplatin induced mitophagy in surviving HCC cells by activating DRP1. The DRP1 inhibitor (Mdivi­1) increased the apoptosis of cisplatin­treated HCC cells by targeting mitophagy. Mechanistically, Mdivi­1 upregulated Bax and downregulated Bcl­xL, leading to an increase in mitochondrial membrane permeability and subsequent release of cytochrome c from mitochondria into the cytosol, thereby aggravating cisplatin­induced apoptosis in HCC cells. Moreover, Mdivi­1 acted synergistically with cisplatin to suppress HCC xenograft growth in vivo. Our results indicate that targeting cisplatin­mediated mitophagy increases HCC apoptosis via DRP1 inhibition, providing preclinical proof of concept for combination therapy targeting mitophagy to potentiate the efficacy of chemotherapy.