Objective:To evaluate the efficacy of 5-LOX inhibitor zileuton on the proliferation and apoptosis of human gastric carcinoma cell line SGC-7901

and to explore the mechanisms of apoptosis induced by zileuton.Methods:The proliferation of SGC-7901 cells was detected by thiazolyl blue tetrazolium bromide(MTT)assays.TUNEL staining was used to evaluate the apoptosis of SGC-7901 cells.The changes of Bax

Bcl-2 and caspase-3 mRNA expression were studied by reverse transcription polymerase chain reaction.Bax

Bcl-2 and caspase-3 protein expression were analyzed by immunocytochemistry in SGC-7901 cells treated with zileuton.Results:Zileuton can decrease the proliferation significantly in a dose-dependent and time-dependent manner in SGC-7901 cells.TUNEL staining showed that the apoptosis rate was elevated with the increase of zileuton concentration(P<0.01).6.2×10-5 mol/L zileuton effectively inhibited the mRNA and protein expression of Bcl-2(P<0.05)

but increased Bax and caspase-3 expression(P<0.05).Conclusion:5 LOX inhibitor zileuton can inhibit proliferation and induce apoptosis of SGC-7901 cells by down regulating the expression of Bcl-2 and up regulating Bax and caspase-3.