Role of autophagy in ursolic acid-induced injury of human umbilical vein endothelial cells

AIM: To investigate the role of autophagy in the injury of human umbilical vein endothelial cells(HUVECs) induced by ursolic acid(UA).METHODS: HUVECs were cultured in vitro with UA at various concentrations for 36 h and the proliferation inhibitory rate of HUVECs was determined by MTT method.The change of ultrastructure was observed under transmission electronic microscope(TEM).The autophagy was observed using fluorescent microscope by monodansylcadaverin(MDC) staining.The protein level and mRNA expression of microtubule-associated protein light chain 3(LC3) and Beclin-1 were detected by Western blotting and RT-PCR,respectively.Cell apoptotic rate was measured by flow cytometry analysis.RESULTS: UA at various concentrations showed significantly dose-dependent inhibitory effect on the proliferation of HUVECs.Autophagy was induced in HUVECs treated with UA as detected by MDC staining and TEM.The protein level and mRNA expression of LC3 and Beclin-1 in HUVECs were significantly increased following the treatment with UA,which was also in a time-dependent manner.Compared with UA group,addition of 3-methyladenine(3-MA) inhibited the increase in autophagic vacuoles and exacerbated the apoptosis.CONCLUSION: Autophagy shows protective effect on the proliferation inhibition of HUVECs induced by UA and the proliferation inhibition can be enhanced by the autophagy inhibitor 3-MA.3-MA may enhance the apoptotic rate of HUVECs induced by UA.