miR-149-5p inhibits cell proliferation and invasion through targeting GIT1 in medullary thyroid carcinoma

Previous studies indicate that miR-149 could both inhibit and promote the development of human cancer depending on the tumor type. GIT1 was found to play an important role in regulating cell migration. However, the specific function of miR-149-5p and GIT1 in the progression of medullary thyroid carcinoma (MTC) remains unknown. The purpose of this study was to confirm the function of miR-149-5p in MTC and explore its downstream regulation. Moreover, miR-149-5p level in MTC was detected via RT-quantitative PCR (RT-qPCR). GIT1 expression levels were assessed by RT-qPCR and western blot analysis. The cell proliferation and invasion were detected through MTT or Transwell assay respectively. In addition, miR-149-5p was identified to directly target GIT1 in MTC via dual luciferase assay. The results suggested that miR-149-5p level was obviously declined in MTC. Functionally, miR-149-5p overexpression inhibited proliferation and invasion. Moreover, miR-149-5p directly targeted GIT1 and was negatively associated with its expression in MTC. Conversely, GIT1 expression was obviously increased in MTC. GIT1 overexpression partially reversed the inhibitory action of miR-149-5p in MTC. miR-149-5p suppressed the proliferation and invasion of MTC cells through targeting GIT1, which would create new therapeutic avenues for MTC treatment.