Dihydroartemisinin induces apoptosis of human gastric cancer cells through mitochondrial pathway

Objective To investigate the molecular mechanism of induction of apoptosis by dihydroartemisinin ( DHA ) in human gastric cancer SGC7901 cells in vitro. Methods Cultured SGC7901 cells were treated with DHA at different concentrations (6.25,12.5,25.0,50.0,and 100.0 μmoL/L)for different durations (24,48,and 72 h),and then the proliferation of cells was assayed by using MTT.SGC7901 cells were treated with DHA at different concentrations for 24 h,and the cell apoptosis rate was analyzed by using flow cytometry ( FCM ).The activities of Caspase-3 and Caspase-9 were assessed by colorimetric assay.The change of mitochondrial trans-membrane potential (△Ψm) was measured by JC-1 staining.The expression levels of bcl-2 and bax were detected by using Western blotting.Western blotting was also used to reveal the amount of Cyto C in cytosol.Results Various concentrations of DHA inhibited the growth of SGC7901 cells in a dose- and time-dependent manner.After SGC7901 cells were treated with DHA for 24 h,as compared with control group ( 1.88 ±0.25),the cell apoptosis rate [(4.21 ±0.83)％,( 6.92 ± 1.26 ) ％,( 9.78 ±2.55 ) ％,( 13.93 ± 2.94)％,(16.02±3.83)％] were increased significantly and the activities of Caspase-3 (0.094 ± 0.008,0.196±0.014,0.288±0.017,0.326 ± 0.024,0.491 ±0.042) and Caspase-9 (0.082 ±0.008,0.154 ±0.010,0.176 ±0.012,0.217 ±0.015,0.268 ±0.024)were increased dose-dependently ( P＜0.05 ). As compared with control group ( 100 ),△Ψm (74.18 ±7.84,70.08 ±6.53,58.66 ± 2.38,48.79 ± 1.31,31.24 ± 0.73 ) was declined significantly ( P ＜ 0.05 ).Western blotting showed that DHA increased bax expression and decreased bcl-2 expression ( P ＜ 0.05 ).The ratio of bcl-2/bax (2.37 ±0.24,1.51 ±0.21,0.82 ±0.16,0.64 ±0.14,0.37 ±0.07) was decreased as compared with control group (3.11±0.28).Western blotting also revealed that the amount of Cyto C (0.21 ± 0.05,0.25 ± 0.06,0.38 ± 0.08,0.39 ± 0.09 ) was increased in cytosol as compared with control group (0.18 ± 0.04 ) ( P ＜ 0.05 ).Conclusion DH A induces the apoptosis of human gastric cancer SGC7901 cells dose-dependently,which is probably mediated by the mitochondrial apoptosis pathway. Key words: Dihydroartemisinin; Gastric cancer; Apoptosis; Mitochondria