miR-509-5p Inhibits the Proliferation and Invasion of Osteosarcoma by Targeting TRIB2

Osteosarcoma (OS) is one of the most common malignant bone tumors in adolescents with a poor prognosis. Though miR-509-5p has been reported as a tumor suppressor in several human cancers, the role of miR-509-5p in OS remains unclear. In this study, our result of real-time PCR (RT-PCR) showed that the expression of miR-509-5p was significantly decreased in OS tissues and cell lines. Overexpression of miR-509-5p significantly suppressed cell proliferation and invasion in OS cell lines. Moreover, we identified tribbles homolog 2 (TRIB2) as the direct target of miR-509-5p. Knockdown of TRIB2 could inhibit the malignant capacity of OS cells. At last, we reported that TRIB2 could inhibit the bioactivity of the tumor suppressor gene p21 via blocking its transcriptional activity. Collectively, our study revealed that miR-509-5p functions as a tumor suppressor by targeting TRIB2 in OS and thus could affect the activity of p21, suggesting that miR-509-5p is a novel preventive intervention for OS patients.