Studies on the mechanisms of shikonin-induced A375-S2 cell apoptosis

Aim To study the mechanisms of shikonin-induced A375-S2 cell apoptosis. Methods Cytotoxicity assay by MTT, DNA fra gmentation assay, caspases activity assay, flow cytometric analysis and Western blot analysis were carried out. Results Shikonin markedly inhibite d A375-S2 cell growth. IC 50 of the 24 h time course was (10.9±1.8) μm ol·L -1. Apoptotic cell death was observed within 24 h after 10 μmol·L -1 shikonin treatment. Shikonin induced A375-S2 cell apoptosis involved in the activation of caspase-3 and caspase-9. Shikonin induced accumulation of p5 3 and up-regulation of Bax and down-regulation of Bcl-xL which are mediated b y p53, resulted in a release of cytochrome C. Shikonin arrested cell cycle at G 1 phase in A375-S2 cells. Conclusion Shikonin induced cell cycl e arrest at G 1 phase in A375-S2 cells, and induced A375-S2 cell apoptosis vi a activation of Bax and caspase-9 mediated by p53.