Diverse effects of G-protein-coupled free fatty acid receptors on the regulation of cellular functions in lung cancer cells.

Free fatty acids (FFAs) are dietary nutrients which mediate a variety of biological effects through binding to G-protein-coupled FFA receptors (FFARs). G-protein-coupled receptor 120 (GPR120) and GPR40 are identified as FFARs for long- and medium-chain fatty acids. Here we investigated whether GPR120 and GPR40 are involved in the acquisition of malignant properties in lung cancer cells. Three lung cancer RLCNR, LL/2 and A549 cells used in this study expressed GPR120 and GPR40 genes. The cell motile activities of all cells were significantly suppressed by a GPR40 antagonist GW1100. In addition, GPR40 knockdown inhibited the cell motile activity of A549 cells. In gelatin zymography, matrix metalloproteinase-2 (MMP-2) activity in GPR40 knockdown was significantly lower than that in control cells. Next, to evaluate effects of GPR120 and GPR40 on cellular functions induced by anti-cancer drug, the long-term cisplatin (CDDP) treated (A549-CDDP) cells were generated. The expression levels of GPR120 and GPR40 were significantly decreased in A549-CDDP cells. While A549-CDDP cells showed the high cell motile activity, GW1100 suppressed the cell motile activity of A549-CDDP cells. These results demonstrate that GPR120 negatively and GPR40 positively regulate cellular functions during tumor progression in lung cancer cells.