VDAC1 oligomerization may enhance DDP-induced hepatocyte apoptosis by exacerbating oxidative stress and mitochondrial DNA damage

Cisplatin (DDP)-based chemotherapy is a preferred treatment for a broad spectrum of cancers, but the precise mechanisms of its hepatotoxicity are not yet clear. Recently, the role of voltage-dependent anion channel protein 1 (VDAC1) in mitochondrial activity and cell apoptosis has attracted much attention. Our aim was to investigate the effects of mitochondrial outer membrane protein VDAC1 oligomerization in DDP-induced hepatocyte apoptosis. L-02 hepatocytes were divided into 4 groups: (a) control group, (b) 4,4'diisothiocyanate-2,2'-disulfonic acid (DIDS; 40 mu m) group, (c) DDP (5 mu m) group, and (d) DDP and DIDS combination group. Cell apoptosis was tested by Annexin V/FITC assay, protein expression of caspase-3, gamma H2AX and NDUFB6 were observed by western blot assay, reactive oxygen species (ROS), and mitochondrial superoxide anion radical (O-2(center dot-)) were detected by DCFH-DA and MitoSOX probe, and DNA damage was assessed by comet assay. Moreover, the activity of mitochondrial respiratory chain complex I was determined by the colorimetry method. Compared with the control group, apoptosis rate and activated cleaved-caspase-3 protein, ROS and O-2(center dot-) generation, DNA damage marker comet tail length, and gamma H2AX protein level increased in the DDP treatment group (P < 0.05). Activity of mitochondrial COXI decreased after DDP treatment (P < 0.05). DIDS, as a VDAC1 oligomerization inhibitor, antagonized DDP-induced apoptosis by diminishing oxidative stress and DNA damage and protecting mitochondrial complex protein. These results show that VDAC1 oligomerization may play an important role in DDP-induced hepatocyte apoptosis by increasing ROS and mtDNA leakage from VDAC1 pores, exacerbating oxidative stress and mtDNA damage.