MiR-9-5p suppresses cell metastasis and epithelial-mesenchymal transition through targeting FOXP2 and predicts prognosis of colorectal carcinoma.

Colorectal carcinoma (CRC) is a common malignant tumor of the digestive tract that occurs in the colon, and the incidence is the third in the gastrointestinal tumor. Recently, the dysregulated expression of microRNA-9 (miR-9) has been identified in many human cancers. However, the special function of miR-9 in the progression of colorectal carcinoma (CRC) remains unknown. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was used to detect the expression of miR-9-5p in 72 pairs of CRC tissues and cell lines. The correlation between miR-9-5p expression and clinical features or prognosis of CRC patients was analyzed. In addition, we examined the mRNA and protein expression levels of forkhead box P2 (FOXP2) using Western blot analysis and qRT-PCR. The functions of miR-9-5p and FOXP2 were investigated using transwell assay and epithelial-mesenchymal transition (EMT). The relation between miR-9-5p and FOXP2 was confirmed by the dual-luciferase assay. In this study, down-regulation of miR-9-5p and up-regulation of the forkhead box P2 (FOXP2) were detected in CRC tissues and cell lines. Moreover, miR-9-5p was found to inhibit cell metastasis and EMT in CRC. In addition, it was confirmed that miR-9-5p directly targeted FOXP2 in CRC. Furthermore, FOXP2 had a carcinogenic effect on CRC. And the overexpression of FOXP2 weakened the suppressive effect of miR-9-5p in CRC. Of note, we observed found that the low expression of miR-9-5p and the high expression of FOXP2 were correlated with poor prognosis of CRC patients. MiR-9-5p suppressed cell metastasis and EMT through targeting FOXP2. Furthermore, dysregulation of miR-9-5p predicted the prognosis of CRC patients. Therefore, miR-9-5p may be a biomarker for cell metastasis and a prognostic factor for CRC patients. MiR-9-5p/FOXP2 axis will provide a new breakthrough in the diagnosis and treatment of CRC.