Abstract: This paper is main to explore the mechanism of autophagy in ursolic acid inducing prostatic cancer PC3 cells apoptosis.PC3 cells were cultured until logarithmic growth phase,then culture medium was insteaded by sugar and amino acid free medium,and ursolic acid of different concentration was joined to intervene.PC3 cells were collected after 72 h,transmission electron microscope and immunofluorescence were used to detect PC3 cells autophagy status;expression of ATG5 and Beclin-1 proteins were detected by western blot;Caspase-3、Caspase-8 and Caspase-9 were detected by Elisa method;and the apoptosis was detected by flow cytometry.The results showed that the autophagy of PC3 cells aggravated obviously after 72 hours.Compared with the control group,cells autophagy in ursolic acid group weaked obviously;The expression of ATG5 and Beclin-1 proteins were reduced markedly(P<0.05),and the content of Caspase-3、Caspase-8 and Caspase-9 were reduced markedly as well(P<0.05).What’s more,the apoptosis rate rised extremely significant(P<0.05).Our datas indicated that Ursolic acid may inhibit autophagy of hungry PC3cells,which might induce cells apoptosis via facilitating the secretion of apoptosis factors.

Key words: ursolic acid, prostatic cancer PC3 cells, autophagy, apoptosis