MicroRNA-613 (miR-613) has been reported to play an important role in the pathogenesis of multiple cancers by negatively regulating gene expression at posttranscriptional level. However, the biological role of miR-613 in osteosarcoma (OS) remained unclear. In this study, we aimed to determine the expression and biological roles of miR-613 in OS. We found that miR-613 was significantly downregulated in OS tissues and cell lines, and that decreased miR-613 expression was correlated negatively with advanced TNM stage and lymph node metastasis. Overexpression of miR-613 in OS cells significantly suppressed the proliferation and colony formation by regulating cell arrest at G0/G1 phase, and impaired the migration and invasive abilities of OS cells, followed by suppression of the epithelial mesenchymal transition (EMT). Bioinformatic and luciferase reporter analysis identified cellular-mesenchymal to epithelial transition factor (c-MET, also named as MET) as a direct target of miR-613. Overexpression of miR-613 significantly inhibited the c-MET expression and its downstream PI3k/Akt/mTOR signaling pathway in OS cells. In OS clinical samples, there was a significant inverse correlation between miR-613 and c-MET mRNA expression. Rescue experiments showed that overexpression of c-MET partially prevented miR-613-induced suppression of OS cell proliferation, colony formation, migration and invasion. In conclusion, we provide first evidence for the suppressive activity of miR-613 by repressing c-MET, suggesting that miR-613 might be a potential therapeutic strategy for OS.
Keywords: c-MET; invasion; miR-613; migration; osteosarcoma; proliferation.