Objective    To investigate the effects of simvastatin on the cell proliferation and apoptosis of K562 cells and to elucidate its molecular mechanisms.     Methods     K562 cells were treated with various concentrations of simvastatin for different times

and then MTT assay was employed to evaluate the proliferation of K562 cells. AnnexinⅤ-FITC/PI staining was performed to confirm the apoptosis of K562 cells. RT-PCR was employed to analyze the mRNA expression levels of MAPK1

cyclin D1

E2F1 and c-myc in K562 cells after simvastatin treatment for 72 h.     Results    Simvastatin inhibited the proliferation of K562 cells

and the inhibitory rate was increased in a dose- and time-dependent manner. K562 cells were induced to apoptosis after the treatment of simvastatin. Compared to control group

the increased apoptotic rate was observed after K562 cells treated with 5

10 and 20 μmol/L simvastatin for 48 h and 72 h. RT-PCR results showed that simvastatin down-regulated the expressions of MAPK1

cyclin D1

E2F1 and c-myc significantly at mRNA level.     Conclusion    Simvastatin inhibits the proliferation of K562 cells and induces them to undergo apoptosis

and the underlying mechanism might be related to down-regulation of some molecules in Ras/MAPK pathway.