miR-139 inhibits osteosarcoma cell proliferation and invasion by targeting ROCK1.

miR-139 has a tumor suppressor effect in many tumors. Here, we examined the suppressive role of this miRNA and its target, ROCK1, in osteosarcoma (OS), a highly malignant bone tumor that mainly affects children and adolescents. The expression of miR-139 was down-regulated in OS. Overexpression of miR-139 significantly inhibited OS cell proliferation, migration, and invasion. Ectopic expression of miR-139 down-regulated ROCK1, a target of miR-139, by direct binding to its 3' untranslated region (3'UTR). Direct  siRNA-mediated silencing of ROCK1 exerted an inhibitory effect on OS cell proliferation and invasion similar to the effect of miR-139. ROCK1 transfection reversed the suppressive effect of miR-139 on OS cell proliferation and invasion. Both miR-139 and siRNA knockdown of ROCK1 significantly down-regulated β-CATENIN and p-AKT and up-regulated E-CADHERIN and p53. The data provided here show that miR-139 exerts suppressive effects on proliferation and invasion of OS cells by targeting ROCK1.