Gambogic acid induces apoptosis of human malignant melanoma A375 cells

【Objective】To investigate the apoptosis-inducing effect of gambogic acid (GA) on A375 human malignant melanoma (MM) A375 cells and the mechanism of apoptosis induced by GA. 【Methods】MTT assay was employed to detect the effects of GA on cellular proliferation and viability; Hoechst staining and flow cytometry assay (FCM) were used to detect the apoptosis of A375 cells with Annexin-V/PI doubling staining; Western blot was applied to assess the expression of Bcl-2 and Bax proteins. 【Results】The IC50 value was (1.57±0.05), (1.31±0.20) and (1.12±0.19) μg/mL respectively after incubation with GA for 24, 36 and 48 hours. The viable apoptotic cells (VA) increased from 27.6% to 41.9% in a dose-dependent manner after A375 cells had been treated with GA (2.5~7.5 μg/ mL) for 36 hours compared with only 3.5% increase of apoptotic cells in the control group. Meanwhile, the protein expression of Bax increased and that of Bc1-2 decreased. 【Conclusion】GA could inhibit the proliferation of A375 human malignant melanoma and induce their apoptosis, which might be related to the down-regulation of Bcl-2/Bax ratio.