ObjectiveTo investigate dihydroartemisinin(DHA)-induced apoptosis of human prostate cancer cells and the underlying molecular mechanism.MethodsNude mice were implanted with human prostate cancer PC-3 cells to establish tumor-bearing mouse model.Twenty models mice were evenly randomized into four groups:control group,solvent group(DMSO),large dose DHA (200 μmol/kg) group and low dose DHA (100 μmol/kg) group.The implanted tumors were observed on day 13 after drug administration.Morphological changes of PC-3 cells were observed by transmission electron microscope(TEM).The protein expression of apoptosis associated gene Bcl-2 and Bax were examined by immunohistochemical method.Apoptosis was detected by TUNEL assay.ResultsTEM examination revealed scattered apoptotic cells and apoptotic bodies in tumor tissues of mice in the DHA groups; immunohistochemical examination revealed that the protein expression of apoptosis-associated gene Bcl-2 was decreased and that of Bax was increased in DHA groups(P<0.05).TUNEL staining revealed that the rate of cell apoptosis increased significantly in DHA groups(P<0.05).ConclusionIt is demonstrated that DHA has strong effect in inducing apoptosis in human prostate cancer cell line PC-3 in vivo,which might be related to the down-regulation of Bcl-2 and up-regulation of Bax.