Salidroside induces apoptosis and protective autophagy in human gastric cancer AGS cells through the PI3K/Akt/mTOR pathway

Salidroside, a natural active ingredient extracted from Rhodiola rosea, has been shown to exert antitumor activity against breast cancer Dong Young et al. [1], colon cancer Sun et al. [2] and bladder cancer Tian et al. [3]. However, the effect of salidroside on apoptosis and autophagy in gastric cancer remains unclear. In our research, we observed the biological effect of salidroside on human gastric cancer AGS cells. Our results demonstrated that salidroside inhibited the growth of AGS cells both in vivo and in vitro and exerted a proapoptotic effect on AGS cells as confirmed by flow cytometry, Hoechst staining and western blot analysis. Additionally, we found that salidroside decreased the phosphorylation of PI3K and Akt and that pretreatment with the PI3K/Akt agonist IGF-1 could weaken the proapoptotic effect of salidroside. Interestingly, the exposure of AGS cells to salidroside induced autophagy as indicated by transmission electron microscopy, mRFP-GFP-LC3 transfection and western blot analysis, suggesting that salidroside promoted autophagy in gastric cancer AGS cells. Furthermore, treatment with the autophagy inhibitor chloroquine enhanced salidroside-induced cell apoptosis, indicating that the autophagy mediated by salidroside may protect AGS cells from death. Additionally, we found that salidroside decreased the level of p-mTOR protein in a concentration-dependent manner and that pretreatment with IGF-1 decreased the expression of autophagy proteins, suggesting that salidroside induced autophagy through the PI3K/Akt/mTOR pathway. The above findings indicate that salidroside inhibited the growth of gastric cancer and induced apoptosis and protective autophagy through the PI3K/Akt/mTOR pathway. In summary, our study provides novel insights regarding the activity of salidroside against gastric cancer and contributes to the clinical application of salidroside combined with autophagy inhibitors as a chemotherapeutic strategy for human gastric cancer.