miR-203 inhibition of renal cancer cell proliferation, migration and invasion by targeting of FGF2

Background: Renal cell carcinoma (RCC) is one of the leading causes of cancer related mortality worldwide. Increasing evidence has shown that microRNAs function as oncogenes or tumor suppressors in human malignancies, but the roles of miR-203 in human RCC is still unclear. Methods: First, quantitative real-time PCR (qRT-PCR) was performed to detect miR-203 expression in renal cancer cell lines and clear cell RCC (ccRCC) specimens. Then, the association of miR-203 expression with clinicopathological features and survival was later analyzed. Finally, the roles of miR-203 in regulation of tumor proliferation, migration, invasion, and target gene expression were further investigated. Results: Our study showed miR-203 was down-regulated in renal cancer cell lines and ccRCC specimens (P < 0.05). Respectively, the low miR-203 expression in ccRCC specimens was associated with advanced clinical features and poorer prognosis (P < 0.05). miR-203 expression was an independent prognostic marker of overall ccRCC patient survival in a multivariate analysis (P < 0.05). Transient forced expression of miR-203 inhibited renal cancer cell growth and metastasis (P < 0.05). In contrast, down-regulation of miR-203 expression promoted renal cancer cell growth and metastasis (P < 0.05). Mechanistic investigations confirmed FGF2 as a direct target of miR-203, and up-regulation of miR-203 could decrease expression of FGF2. Further investigation showed that ectopic expression of FGF2 partially reversed the inhibition effect of enforced miR-203 expression on the malignant phenotypes of renal cancer cells. Conclusions: Our study suggested that miR-203 could be a potential prognostic marker and functions as a tumor suppressor in human renal cancer by post-transcriptionally targeting FGF2.