[Apoptosis-inducing effect of gambogic acid on K562 cells and its mechanism].

This study was aimed to investigate the apoptosis-inducing effect of gambogic acid (GA) on K562 cell line and its mechanism. The K562 cells were treated with GA at different concentrations and times, the inhibition rates were detected by MTT assay. Apoptosis induced by GA was assayed by Annexin-V/PI doubling staining. The influence of GA on cell cycle was studied by propidium iodide method. The mitochondrial membrane potential was measured by JC assay. The levels of caspase 3, caspase 8 and caspase 9 activated by fluorescein in living K562 cells were measured by caspGLOW(TM) fluorescein staining kit. The results showed that after incubation with GA, K562 cell proliferation was dramatically inhibited in concentration- and time-dependent manners. K562/A02 cells need higher GA concentration (> 2 microg/ml) to show antiproliferative effect, compared with that of K562 cells (> 0.5 microg/ml). Apoptosis could be induced by GA but the influence on cell cycle was not significant. GA could decrease the mitochondrial membrane potential and increase the activated caspase 3, caspase 8, caspase 9 positive cell levels by 2.19%, -1.95%, 34.01% in 24 hr and 60.4%, 71.3%, 77.7% in 48 hr respectively. It is concluded that the GA can significantly inhibit the proliferation of K562 cells without influence on cell cycles. The GA triggers K562 cell apoptosis through both intrinsic and extrinsic pathways.