Preliminary Investigation of the Molecular Mechanism of Empagliflozin Suppressing Gastric Cancer Through Mammalian Target of Rapamycin

  Objective   To predict the intervention targets of empagliflozin (EMPA), a specific inhibitor of sodium-glucose cotransporter 2 (SGLT2), in gastric adenocarcinoma through comprehensive network pharmacology, and to validate the effects and the molecular mechanisms of EMPA through cellular and molecular biology experiments.

  Methods   Bioinformatics analysis of gastric adenocarcinoma was conducted to assess the correlation between gastric adenocarcinoma prognosis and SGLT2 expression. Network pharmacology was utilized to identify shared targets of EMPA and gastric adenocarcinoma. AGS cells, a human gastric adenocarcinoma cells line, were incubated with EMPA at different concentrations for 24 h and, then, cell proliferation was assessed using the CCK8 assay. After AGS cells were incubated with EMPA at the doses of 0, 3, and 6 mmol/L, real-time cell analysis (RTCA) and 5-ethynyl-2-deoxyuridine (EdU) incorporation were used to evaluate EMPA's inhibitory effects on the proliferation of the AGS cells. In addition, wound healing and Transwell assays were performed to assess the inhibitory effect of EMPA on the migration and invasion of the APC cells and Western blot analysis was conducted to examine the expression of mammalian target of rapamycin (mTOR) and phosphorylated mTOR (p-mTOR). BALB/c (nu/nu) nude mice were implanted with 5×10⁶ AGS cells in the axilla. The mice were divided into three groups, a control group, a low-dose group, and a high-dose group, each consisting of 7 mice. After one week, the control group received daily intraperitoneal injections of normal saline, while the low-dose group and high-dose group received daily intraperitoneal injections of EMPA at the doses of 3 mg/kg and 5 mg/kg, respectively. The tumor volume was measured one week after the drug intervention started.

  Results  Gastric adenocarcinoma patients with low expression of SGLT2 exhibited longer survival time and higher survival rate than those with high expression of SGLT2 did. A total of 104 EMPA-related potential targets and 2028 targets associated with gastric adenocarcinoma were identified. Among these, 45 targets associated with gastric adenocarcinoma overlapped with potential targets of EMPA. Further analysis revealed 10 relevant pathways and 4 core genes. The core genes were cyclin-dependent kinase 4 (CDK4), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), mTOR, and cyclin E1 (CCNE1). CCK-8 assay revealed that EMPA at concentrations ranging from 0.39 to 50 mmol/L effectively inhibited the proliferation of AGS cells. RTCA results indicated a downward shift in the cell growth curve. In comparison to the findings for the control group, EdU assay demonstrated that EMPA at the concentrations of 3 mmol/L and 6 mmol/L significantly inhibited AGS cell proliferation (P<0.05). Results from wound healing and Transwell assays indicated a decrease in the levels of cell migration and invasion (P<0.05) and, notably, there was a significant difference between the high and low-dose EMPA groups (P<0.05). Western blot showed no statistically significant difference in the expression of total mTOR protein between the groups. However, the expression of p-mTOR in the 3 mmol/L and 6 mmol/L EMPA groups decreased compared to that of the control group (P<0.05), with the 6 mmol/L EMPA group exhibiting a more pronounced reduction (P<0.05). Nude mice xenograft tumor experiment demonstrated that, compared to that of the control group, the tumor volumes in the EMPA-treatment groups were significantly reduced (P<0.05), with the high-dose group showing a more pronounced reduction (P<0.05).

  Conclusion  EMPA inhibits the abnormal proliferation and migration of gastric adenocarcinoma cells, potentially through the modulation of mTOR protein activation. This study provides new potential medication and intervention targets for gastric adenocarcinoma treatment.