Objective:To investigate the proliferation inhibition and apoptosis in human prostatic carcinoma cell line PC-3 induced by ursolic acid and their mechanism.Methods:PC-3 were treated by ursolic acid with different concentration and time.MTT assay

flow cytometry(FCM)

SP method of immunocytochemistry

Western blot were used to observe the cell proliferation inhibition

cell cycle and apoptosisrate

the expressions of bcl-2

cox-2

bax and caspase 3.Results:Ursolic acidinhibited the proliferation of PC-3 cells in dosage and time dependent manner.The IC50 of PC-3 cells that were treated by ursolic acid for 24

48 h and 72 h are 50.87

37.91μmol/L and 27.86 μmol/L.The apoptosis rate of the PC-3 cells hightened with the increasing of the ursolic acid density and time.The apoptosis rates of the PC-3 cells that treated by 50 μmol/L ursolic acid for 24

48 h and 72 h are 6.21

7.81% and 13.31%.Ursolic acid induced a G1 cell cycle arrest and reduced the cell population in S phase.With the increasing of the medicine density

the expression of bcl-2 and cox-2 was down-regulated

while the expression of bax and caspase 3 up-regulated in the apoptosis.Conclusion:Ursolic acid can inhibit proliferation of the PC-3 cells and induced a G1 cell cycle arrest and reduced the cellpopulation in S phase.It also can induce apoptosis of human prostatic carcinoma through down-regulating the expressions of bcl-2 and cox-2

up-regulating the expression of bax

and caspase3.