ABSTRACT
@# Objective: To observe the effect of ursolic acid (UA) on autophagy and apoptosis of gastric cancer cell line MGC-803, and to explore the mechanism of UA-induced autophagy of MGC-803 cells based on PI3K/AKT/mTOR signaling pathway. Methods: Human gastric cancer cell line MGC-803 was cultured in vitro and divided into blank control group, UAintervention group and UA+3-MA group. The cell apoptosis in each group was detected by flow cytometry. Cell autophagy was detected by double fluorescence mRFPeGFP-LC3 plasmid transfection method. The mRNA expression levels of LC3B, BAX and Bcl-2 were detected by qPCR. The protein expression levels of PI3K type I, p-AKT, p-mTOR, ULK1, LC3B, BAX and Bcl-2 were detected by WB. Results: Flow cytometry showed that the cell apoptotic rate of UA intervention group was significantly higher than that of blank control group (P<0.05). Compared with UAintervention group, the apoptotic rate in UA+ 3-MAgroup was significantly reduced (P<0.05). The double fluorescence mRFP-eGFP-LC3 plasmid transfection method showed that the green and red fluorescent bright spots in UA intervention group increased significantly compared with the blank control group (P<0.05), and the green and red fluorescent bright spots in UA+3-MA group were significantly reduced compared with UA intervention group (P<0.05). Real-time quantitative PCR and WB method showed that compared with the blank control group, the mRNAand protein expressions of BAX and LC3B, and ULK1 protein were significantly increased in UA intervention group, while the mRNA and protein expressions of Bcl-2, and the protein expressions of PI3K, p-AKT and p-mTOR were significantly decreased in UA intervention group (all P<0.05); Compared with UA intervention group, mRNA and protein expressions of BAX and LC3B were significantly down-regulated and the mRNAand protein expressions of Bcl-2 were significantly up-regulated in UA+3-MA group (all P<0.05), while protein levels of PI3K, p-AKT, p-mTOR and ULK1 were not significantly changed in UA+3-MA group (P>0.05). Conclusion: UA can promote apoptosis of MGC-803 cells via inducing autophagy, which may be related to UA's involvement in regulating the expressions of PI3K/AKT/mTOR signaling pathway-related proteins.