ABSTRACT
AIM:To investigate the role of autophagy in inhibition of human lung cancer PC 9 cell proliferation by ursolic acid(UA)as well as the underlying mechanism.METHODS:MTT assay and Trypan blue exclusion test were performed to analyze the effect of UA on the proliferation of PC 9 cells.The PC9 cells were treated with UA,and autophagy was observed under fluorescence microscope through acridine orange staining.The expression of autophagy-associated pro-teins LC3 and ATG5 in the PC9 cells were detected by Western blot.The effect of UA,3-methyladenine(3-MA)3-MA or their combination on the cell viability was measured by MTT assay.RESULTS:The viability of PC9 cells was significantly inhibited by UA(P<0.05 or P<0.01).The number of bright red fluorescence positive cells was significantly increased after treatment with UA.The protein expression of LC3-II and ATG5 was significantly up-regulated compared with control group(P<0.01).Furthermore,combination of UA and 3-MA resulted in a substantial decrease in cell viability compared with using UA alone(P<0.01).CONCLUSION: UA inhibits the proliferation and induces the autophagy of the PC 9 cells,in which autophagy plays a protective role.The inhibition of autophagy significantly promotes the death of the PC 9 cells induced by UA.