The Effect Of Proliferation Inhibition And Apoptosis Induction Of Icariin On NB4Leukemia Cells And Its Molecular Mechanisms

Objective: Effects of icariin（ICA）on proliferation,cell cycle and apopto-sis of NB₄cell were investigated in vitor. Meanwhile we approached Anti-tumor mechanism of ICA initially. this study provides some theoretical bases toclinical application of ICA to cancer.Methods:1The effect of ICA on NB₄cells was evaluated with varying conc-entration of ICA （0,4,8,16,32,and64μmol/L）treatment for24,48and72hoursby MTT assay.2The cell cycle of NB₄cell treated by ICA （8,16,32and64μmol/L）for48hours were detected by flow cytometry（FCM）.3The apoptosis of NB₄cell treated by ICA （4,8,16,32and64μmol/L） for48hours were detected by flow cytometry（FCM）.4The role of Bax and Bcl-2family proteins in apoptosis on NB₄cell,which were treated by ICA（8,16,32and64μmol/L）for48hours wasanalyzed by western blotting.Results:1Using the NB₄cell, we found that ICA treatment ecerted a significantcytotoxic effect upon NB₄cells indose-dependent（0,4,8,16,32,64μmol/L）andtime-dependent（24,48and72hours）manner.2The treatment by ICA（8,16,32,64μmol/l）for48hours,compared with thevehicle-treated controls,resulted in an appreciable arrest NB₄cell in G1phase ofcell cycle by FCM.3Varying concentration of ICA treatment ecerted a significant apoptosiseffect., After incubated with4、8、16、32、64μmol/L quercetin for48h, total apoptosis rate of NB₄cells increased from6.52%of control group to29.41%（P＜0.05）.4ICA can significantly up-regulate Bax protein and down-regulate Bcl-2protein. The levels of these proteins are dose-dependent in response to ICA.Theratio of Bax/Bcl-2was significantly increased in a dose-dependent manner withICA treatment.Conclusion:Our data suggested ICA treatment resulted in a significant dose andtime-dependent inhibition on proliferation,cell cycle and apoptosisof NB₄cell.Our study also suggests that ICA causes cell cycle arrest in G1phase.inturns ICA can significantly up-regulate Bax protein and down-regulate BCL-2protein.