MicroRNA-665 suppressed the invasion and metastasis of osteosarcoma by directly inhibiting RAB23.

MicroRNAs (miRNAs) are small, short and noncoding RNAs that regulate gene expression posttranscriptionally. Increasing evidences have demonstrated that deregulated expression of miRNAs is found in osteosarcoma. In this study, we demonstrated that miR-665 was downregulated in osteosarcoma tissues compared to non-tumorous tissues. The overall survival (OS) of osteosarcoma patients with low miR-665 expression was lower than that of these patients with high miR-665 expression. Ectopic expression of miR-665 suppressed the osteosarcoma cell proliferation, EMT and invasion. We identified Rab23 as a direct target gene of miR-665. Rab23 was downregulated in osteosarcoma tissues and cell lines. The expression of miR-665 was inversely associated with the expression of Rab23 in the osteosarcoma tissues. These results suggested that miR-665 acted as a tumor suppressor gene in the development of osteosarcoma.