Triptolide Inhibits Proliferation and Induces Apoptosis in Human Melanoma A375 Cells

As the most aggressive form of skin cancer, cutaneous malignant melanoma (CMM) frequently affects young individuals, with a mean age of 50 years (Ferrari et al., 2008). Because of the resistance to current conventional therapeutic methods of CMM, approximately 13,000 deaths of CMM happen every year, but this has not been paralleled by the development of new therapeutic agents with an ideal effect (Finn et al., 2012).Therefore, efforts to develop new therapeutic approaches are in urgent need. Triptolide is a diterpenoid triepoxide and the principal active ingredient of Tripterygium wilfordii Hook. f. (Leigongteng) (He et al., 2009). It has been reported to have pharmacological and biochemical properties in the treatment of rheumatoid arthritis and several other autoimmune and inflammatory diseases, including immune complex nephritis and systemic lupus erythematosus (Lu et al., 2011). Besides, triptolide has been shown to have antitumor properties in a variety of human tumor cells via inhibiting cell proliferation and inducing apoptosis (Mujumdar et al., 2010; Meng et al., 2011; Wu et al., 2011). Despite the recognized potent antitumor activity of triptolide, our knowledge regarding its mechanisms of action is still limited. However, the effect of triptolide on human melanoma A375 cells has not yet been investigated. Thus, we managedto identify the mechanism of triptolideinduced apoptosis in human melanoma cells in vitro. As cancer is a disease of deregulated cell proliferation and survival, deregulated cell cycle and inhibition of cell