Abstract: Objective To explore the effect and mechanism of iso-suillin on the apoptosis of human gastric cancer BGC-823 cells based on the ROS/PI3K/Akt signaling pathway. 
Methods Human gastric cancer BGC-823 cells were cultured in vitro and treated with iso-suillin at different concentrations of 7 μmol/L, 14 μmol/L, and 28 μmol/L for 48 h. The intervention with iso-suillin at a concentration of 7 μmol/L was defined as the low-dose group, the intervention with iso-suillin at a concentration of 14 μmol/L was defined as the medium-dose group, and the intervention with iso-suillin at a concentration of 28 μmol/L was defined as the high-dose group. In the meantime, a control group was set up(intervention with the same amount of normal saline for 48 h). The Hoechst 33342 fluorescent staining method was used to observe the morphological changes of human gastric cancer BGC-823 cells after treatment with iso-suillin, and Western blot was used to detect the expression level of apoptosis-related protein in human gastric cancer BGC-823 cells after treatment with iso-suillin. 2,7-dichlorofluorescin diacetate(DCFH-DA) fluorescent probe was used to detect the level of reactive oxygen species(ROS) in human gastric cancer BGC-823 cells treated with iso-suillin, and western blot was used to detect the expression levels of PI3K/Akt signaling pathway-related proteins. 
Results Hoechst 33342 fluorescent staining showed that an increase in iso-sullin concentration led to more bright blue cells, chromatin condensation, and appearance of apoptotic bodies. Compared with the control group, the apoptosis rate of low-dose group, medium-dose group and high-dose group increased(P＜0.05). The relative expression of Caspase-3, Caspase-8, Caspase-9 and Bax increased in low-dose group, medium-dose group and high-dose group, while the relative expression of Bcl-2 decreased(P＜0.05). Compared with the control group, the ROS level of BGC-823 cells in low-dose group, medium-dose group and high-dose group increased(P＜0.05). The relative expression of PI3K, Akt and mTOR proteins in PI3K/Akt signaling pathway decreased with the increase of iso-sullin concentration(P＜0.05). 
Conclusion Iso-suillin can induce apoptosis of human gastric cancer BGC-823 cells, and its mechanism may be related to the up-regulation of ROS and down-regulation of PI3K, Akt and mTOR proteins in the PI3K/Akt signaling pathway.

Key words: stomach neoplasms, iso-suillin, BGC-823 cells