Reactive oxygen species generation is essential for cisplatin-induced accelerated senescence in hepatocellular carcinoma

Accelerated senescence is important because this process is involved in tumor suppression and has been induced by many chemotherapeutic agents. The platinum-based chemotherapeutic agent cisplatin displays a wide range of antitumor activities. However, the molecular mechanism of cisplatin-induced accelerated senescence in hepatocellular carcinoma (HCC) remains unclear. In the present study, the growth inhibitory effect of cisplatin on HepG2 and SMMC-7721 cells was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cellular senescence was then assessed by beta-galactosidase assay. Senescence-related factors, including p53, p21, and p16, were evaluated by quantitative reverse transcription-polymerase chain reaction. Reactive oxygen species (ROS) was analyzed by flow cytometry. Our results revealed that cisplatin reduced the proliferation of HepG2 and SMMC-7721 cells in a dose- and time-dependent manner. Senescent phenotype observed in cisplatin-treated hepatoma cells was dependent on p53 and p21 activation but not on p16 activation. Furthermore, cisplatin-induced accelerated senescence depended on intracellular ROS generation. The ROS scavenger N-acetyl-L-cysteine also significantly suppressed the cisplatin-induced senescence of HepG2 and SMMC-7721 cells. In conclusion, our results revealed a functional link between intracellular ROS generation and cisplatin-induced accelerated senescence, and this link may be used as a potential target of HCC.