Objective:To investigate the effects of sodium selenite on the cell apoptosis of K562 cells and to elucidate its molecular mechanisms.Methods:K562 cells were treated with various concentrations of sodium selenite at different time points

and then MTT assay was employed to evaluate the effects of sodium selenite on the proliferative inhibition of K562 cells.MTT assay was employed to evaluate the effects of sodium selenite on the proliferative inhibition of K562 cells.Electronmicroscopy

and TUNEL were performed to confirm the apoptosis of K562 cells

RT-PCR was employed to analyze the mRNA expression levels of Bcl-2 and Bax.Colorimetric method were used to measure the activities of caspase-3 of K562.Results:Sodium selenite could inhibit proliferation of K562 cells and induce them to undergo apoptosis.RT-PCR results showed that sodium selenite could decrease the mRNA expression level of Bcl-2 and increase the level of Bax of K562 cells which had been treated with sodium selenite for 48h significantly

and the activity of caspase-3 elevated remarkably too.Compared with the control group

the expression levels of Bcl-2

Bax and acivity of caspase-3 in 20μmol/L sodium selenite treatment group were markedly changed(P<0.05).Conclusions:Sodium selenite can induce K562 cells to undergo apoptosis.The decrease of mRNA expression level of Bcl-2

the increase of Bax and activity of caspase-3 may be its mechanisms.