MicroRNA-211 inhibits tumor growth and invasion through directly targeting RUNX 2 in osteosarcoma

Osteosarcoma is the most common primary neoplasm of the bone and mainly occurs in adolescents and young adults. Despite great progress in current treatments, approximately one-third of patients with OS will not survive for more than five years, and fewer than 50% will live more than ten years. Aberrantly expressed microRNAs contribute to the carcinogenesis and progression of human cancers, including osteosarcoma. Increasing studies suggested that microRNA-211 (miR-211) might play important roles in the development of various cancer types; however, the expression patterns, roles and its underlying mechanism of miR-211 in osteosarcoma remain largely unexplored. In this study, we demonstrated that miR-211 was significantly downregulated in osteosarcoma tissues and cell lines compared with their adjacent normal tissues and human normal osteoblastic cell line, respectively. Functional studies showed that resumption of miR-211 inhibited cell proliferation, migration and invasion in osteosarcoma. Runt-related transcription factor 2 (Runx2) was validated as a direct target gene of miR-211. In addition, RUNX2 mRNA expression was upregulated in osteosarcoma tissues and inversely correlated with miR-211 expression. Furthermore, upregulation of RUNX2 could partially rescue the antitumor effects of miR-211 in OS cells. Taken together, these findings indicated the essential roles of miR-211 in suppressing osteosarcoma progression, suggesting miR-211 as a potential therapeutic target for the treatment of osteosarcoma.