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

AIMS: 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.

MAIN METHODS: 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.

KEY FINDINGS: 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.

SIGNIFICANCE: 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.