Abstract: Objective To investigate the effects of Res on the growth of skin cancer cell line A431 and benign epidermal keratinocyte cell line HaCaT in human and its mechanism. In addition, to evaluate the potential value of Res as a natural antitumor drug. Methods A431 and HaCaT cells were incubated in HDMEM medium containing 10% serum and 1% SP, then they were each treated with different concentrations of Res and DDP. MTT assay was used to measure the inhibitory rate. Phase contrast microscope was used to observe the morphological changes of A431 cells treated with Res. The effects of Res on A431 cell apoptosis was evaluated by flow cytometry, the expression of Caspase-3 and Bcl-2 proteins were analysed by SP immunohistochemistry. Results 1) The results of MTT assay showed that both Res and DDP could inhibit A431 cell proliferation in time-dependent and dose-dependent manners. At their respective IC50, the inhibitory rate of DDP was higher than that of Res on HaCaT cells(P<0.05). 2) Inhibitory effects of Res on the growth of A431 cells could be seen under Phase contrast microscope, with the increase in Res concentration, the adhesion ability of A431 cell decreased, many cells shed from the vessel wall and floated on the culture medium. Flow cytometry detected that typical apoptosis took place in A431 cells, when treated with 15 mg/L and 20 mg/L Res for 48 h, the apoptosis rate of A431 cells showed a dose-dependent manner, When treated with 15 mg/L for 24 h, 48 h and 72 h, the apoptosis rate of A431 cells showed a time-dependent manner; Compared with the control group, after treatment with Res, the expression of caspase-3 increased and Bcl-2 decreased in A431 cell. Conclusion Res, which is less toxic than DDP, can inhibit proliferation and induce apoptosis of A431 cell. The possible molecular mechanisms of apoptosis might be related to the increasing expression of caspase-3 and the decreasing expression of Bcl-2.

Key words: Res, DDP, A431 cell line, skin cancer, Bcl-2, Caspase-3