Objective:To investigate the mechanism of ursolic acid inducing the apoptosis of human nasopharyngeal carcinoma cell line CNE-2Z.Methods:CNE-2Z were treated by ursolic acid with different concentration.Cell proliferation was determined by MTT assay.Cell cycle and apoptosis rate were analysed by flow cytometry(FCM).The expressions of bax

bcl-2 and cox-2 were assessed by SP method of immunocytochemistry

while the expression of caspase 3 by Western blot.Results:Ursolic acid inhibited the proliferation of CNE-2Z cells and induced the apoptosis in dosage and time dependent manner.FCM showed that the cell population reduced in S phase and cell cycle was arrested in G0/G1 phase.Immunocytochemistry showed that the expression of bax was up-regulated in the apoptosis

while the expression of bcl-2 and cox-2 down-regulated.Western blot showed that the expression of caspase 3 was strengthened.Conclusion:Ursolic acid can induce apoptosis of CNE-2Z in vitro.Its molecular mechanism probably is through promoting activation of caspase3

up-regulating the expression of bax

and down-regulating the expressions of bcl-2 and cox-2.