miR-203 inhibits cell proliferation, invasion, and migration of non-small-cell lung cancer by downregulating RGS17

Involvement of the RGS17 oncogene in the promotion of non-small-cell lung cancer (NSCLC) has been reported, but the regulation mechanism in NSCLC remains unclear. MicroRNAs (miRNAs) negatively regulate gene expression, and their dysregulation has been implicated in tumorigenesis. To understand the role of miRNAs in Regulator of G Protein Signaling 17 (RGS17)-induced NSCLC, we showed that miR-203 was downregulated during tumorigenesis, and inhibited the proliferation and invasion of lung cancer cells. We then determined whether miR-203 regulated NSCLC by targeting RGS17. To characterize the regulatory effect of miR-203 on RGS17, we used lung cancer cell lines, A549 and Calu-1, and the constructed miR-203 and RGS17 overexpression vectors. The CCK8 kit was used to determine cell proliferation, and the Transwell® assay was used to measure cell invasion and migration. RT-PCR, western blots, and immunofluorescence were used to analyze expression of miR-203 and RGS17, and the luciferase reporter assay was used to examine the interaction between miR-203 and RGS17. Nude mice were used to characterize in vivo tumor growth regulation. Expression of miR-203 inhibited proliferation, invasion, and migration of lung cancer cell lines A549 and Calu-1 by targeting RGS17. The regulatory effect of miR-203 was inhibited after overexpression of RGS17. The luciferase reporter assay showed that miR-203 downregulated RGS17 by direct integration into the 3'-UTR of RGS17 mRNA. In vivo studies showed that expression of miR-203 significantly inhibited growth of tumors. Taken together, the results suggested that expression of miR-203 inhibited tumor growth and metastasis by targeting RGS17.