MicroRNA-139 inhibits the proliferation and migration of osteosarcoma cells via targeting forkhead-box P2.

Osteosarcoma (OS) is the most common primary bone malignancy that affects adolescents. Although great attention has been paid to the diagnosis of and therapy for OS, the 5-year survival rate of patients with this disease remains poor. MicroRNAs are small non-coding RNAs involved in pathogenesis and progression of human malignancies. MiR-139 has been implicated in several human cancers. However, the role played by miR-139 in pathogenesis of human OS has remained largely unknown. Realtime PCR was used to detect the expression of miR-139. CCK-8, BrdU-ELISA and ApoTox-Glo™ Triplex assay was employed to detect the proliferation and apoptosis of osteosarcoma cells. Realtime PCR, Western Blotting and luciferase report assays were conducted for the target genes analysis. The expression of miR-139 was reduced while the expression of forkhead-box P2 (FOXP2) was induced in both OS tissue and cell lines. The reduced level of miR-139 was correlated with tumor size, clinical stage and distant metastasis. Overexpression of miR-139 inhibited the expression of FOXP2, which suppressed cell growth, but induced apoptosis. Further, we confirmed that FOXP2 was a direct target of miR-139 by luciferase reporter assay. Knockdown of FOXP2 resulted in reduced levels of cell proliferation, but increased levels of apoptosis in vitro. These findings suggest that miR-139 plays a suppressive role in the regulation of OS cell proliferation and migration via directly targeting FOXP2, which might be a potential clinical diagnostic or predictive biomarker for human OS.