Abstract: OBJECTIVE: To investigate the expression of autophagy and accumulation of reactive oxygen species (ROS) after human gastric cancer SGC-7901 cells were treated with vitamin E succinate (VES). METHODS: Human gastric cancer SGC-7901 cells were treated with VES at different doses (0,5,10,15,20 μg/mL) for 24 h. Then,laser confocal microscopy was used to observe fluorescence intensity and distribution of the autophagy marker protein:microtubule-associated protein 1 light chain 3 (LC3). Western blot was used to evaluate the expression levels of LC3 and Beclin-1. Flow cytometry was used to detect the level of intracellular ROS. In addition,cells exposed to 20 μg/mL VES for 24 h with or without antioxidant N-acetyl-L-cysteine (NAC,20 mmol/L),were observed for fluorescence intensity and distribution of LC3. Western blot was used to evaluate levels of LC3 and Beclin-1. Furthermore,cells with BECN-1 knocked-down by RNA interference were treated with 20 μg/mL VES for 24 h. Then,flow cytometry was used to detect the level of intracellular ROS. RESULTS: Compared with the control group,VES treatment increased the amount of intracellular LC3 punctate fluorescence and the number of autophagic vacuoles,and increased the expression of endogenous autophagy marker protein LC3 and Beclin-1. Flow cytometry showed that the level of intracellular ROS was gradually increased. When ROS production was reduced by the antioxidant NAC,the fluorescence intensity of LC3,the expression of LC3 and Beclin-1 were significantly lower compared with VES-treatment alone. After the cells were transfected with BECN-1 siRNA,the level of intracellular ROS was higher compared with VES alone. CONCLUSION: VES induced autophagy and accumulation of ROS in human gastric cancer SGC-7901 cells. In addition,there were interactions between autophagy and ROS level in VES-treated cells.

Key words: vitamin E succinate, gastric cancer cells, autophagy, reactive oxygen species