Abstract: Objective To investigate the impact of miR-21 on proliferation and apoptosis in HepG2 cells in vitro. Methods HepG2 cells were divided into three groups,intervened respectively by Lipofectamine 2000/Hsa-miR-21 mimics（enhancement）,Lipofectamine 2000/Has-miR-21 inhibitor（inhibition） and Lipofectamine 2000（control）. The expression of B-cell translocation gene 2（BTG2） protein was detected by Western blot,cell proliferation by CCK-8,and cell cycle and apoptosis by flow cytometry（FCM）. Results The expression of BTG2 in enhancement group decreased obviously and it increased in inhibition group,which were significantly different as compared to that in the control（P<0.05）;the proliferation of HepG2 cells in inhibition group decreased significantly as compared to those in enhancement or control cell（P<0.05）,while it increased obviously as compared to that in the control（P<0.05）;the proportion of S phase cells in inhibition group decreased markedly as compared to those in the enhancement or control （P<0.05）,while G2 phase cells obviously increased （P<0.05）,and S phase cells in enhancement increased and G2 cells decreased as compared to that in the control（P<0.05）;the apoptosis in inhibition obviously increased as compared to those in the enhancement or control（P<0.05）,while it in enhancement significantly decreased as compared to that in the control（P<0.05）. Conclusion MiR-21 might play an important role in hepatocarcinogenesis by intervention of BTG2 expression,which might be a new approach to deal with hepatocellular carcinoma.

Key words: HepG2 cells, miR-21, B-cell translocation gene 2 Proliferation, Apoptosis, In vitro