Abstract:

OBJECTIVE: To study whether apigenin could induce autophagy in human gastric cancer SGC-7901 cells and whether the induced autophagy would affect apoptosis in these cells. METHODS: SGC-7901 cells were treated with different doses (0,20,40,60,80 μmol/L) of apigenin (API) for 24 h. Cell survival rates were measured using the MTT method. In addition,cells were treated with 60 μmol/L API for different hours(0,12,24,36,48 h). Western blot was used to evaluate the autophagy marker protein microtubule-associated protein 1 light chain 3 (LC3),Beclin-1 and the activities of p-Akt and p-mTOR,the critical targets of Akt/mTOR signaling pathway. Electron microscopy was used to observe autophagy. Furthermore, cells were treated with autophagy inhibitor,chloroquine(CQ) and 3-mehtyladenine (3-MA) and 60 μmol/L API. Western blot analyses were performed to detect changes in LC3,Beclin-1 and PARP. Annexin V-FITC/PI was used to detect the apoptotic rate. RESULTS: SGC-7901 cell viability was inhibited under API treatment in a does-response manner. With increasing doses of API,autophagic vesicles and autophagosome began to appear in electron microscopy. Western blot analysis showed that LC3-Ⅱ and Beclin-1 protein levels increased in cells treated with API (P < 0.05). The phosphorylation levels of Akt and mTOR were reduced. After inhibiting autophagy,the expression of LC3 Ⅱ and Beclin-1 proteins in the API group was significantly higher than that in the control group(P < 0.05). There was no significant difference in the other groups. Cleaved PARP and apoptotic rate increased significantly in API+CQ and API+3-MA then control and API. CONCLUSION: API can induce autophagy in human gastric cancer cells SGC-7901 via the Akt/mTOR signaling pathway. The API-induced autophagy could significantly increase API-induced apoptosis in these cells. Furthermore,API-induced autophagy can protect survival of gastric cancer cells.

Key words: apigenin, gastric cancer, autophagy, apoptosis