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

Abstract

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 μm) group, (c) DDP (5 μm) group, and (d) DDP and DIDS combination group. Cell apoptosis was tested by Annexin V/FITC assay, protein expression of caspase‐3, γH2AX and NDUFB6 were observed by western blot assay, reactive oxygen species (ROS), and mitochondrial superoxide anion radical (O2•−) 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 O2•− generation, DNA damage marker comet tail length, and γH2AX 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.

Keywords

• 4,4'‐diisothiocyanatostilbene‐2,2'‐disulfonic acid
• apoptosis
• cisplatin
• hepatocyte
• oligomerization
• voltage‐dependent anion channel 1