GPR120 promotes radiation resistance in esophageal cancer via regulating AKT and apoptosis pathway.

The aim of the study is to investigate the role of GPR120 on the biological behavior of esophageal cancer cells in the setting of radiation and explore the mechanism. GPR120 knockdown was fulfilled by siRNA-mediated effects in two esophageal cancer cell lines Eca109 and EC9706. Colony formation, survival fraction calculation, viable cell evaluation by cell counting kit-8 assay and cell apoptosis analysis by phycoerythrin annexin V and 7-amino-actinomycin (7-AAD) staining and the flow cytometry examination was evaluated in Eca109 and EC9706 under the treatment of different radiation dosage. The mechanisms were explored by the evaluation of the Akt pathway and apoptosis protein level. Significantly decreased GPR120 mRNA and protein after GPR120 siRNA treatment compared to control siRNA treatment. Significantly decreased colony formation was found in GPR120 siRNA-treated Eca109 and EC9706 cells compared to control siRNA-treated cells at the radiation dosage of 2, 4, 6 and 8 Gy. Moreover, decreased survival fraction number with increased sensitive enhancing ratio was also found in GPR120 siRNA-treated Eca109 and EC9706 cells compared to control siRNA-treated cells. Decreased cell viability and increased cell apoptosis in GPR120 siRNA-treated esophageal cancer cells. GPR120 siRNA decreased the Akt phosphorylation and anti-apoptotic Bcl-2 expression level, but increased pro-apoptotic Bim expression level in esophageal cancer cell lines. GPR120 regulated the biological behavior of the esophageal cancer cells via affecting Akt pathway and apoptosis molecules. Moreover, GPR120 siRNA combined radiation treatment could be a therapeutic choice for esophageal cancer.