MiR-135b promotes proliferation and invasion of osteosarcoma cells via targeting FOXO1.

Recent data strongly suggest the important role of miRNAs in various cancer-related processes. Osteosarcoma (OS) is the most common primary cancer of the bone and usually leads to deaths due to its rapid proliferation and metastasis. Here, we demonstrated that compared with noncancerous bone tissues, miR-135b expression is frequently upregulated in OS specimens, inversely correlated with potential target-FOXO1 expression pattern. Bioinformatics analysis combined with experimental confirmation revealed FOXO1 is a direct target of miR-135b in OS. Functionally, miR-135b inhibitor significantly inhibited OS cells proliferation and invasion. Forced expression of FOXO1 showed the opposite effect, and FOXO1 knockdown abolished the effect of miR-135b inhibitor. Taken together, our data provide compelling evidence that miR-135b functions as an onco-miRNA in OS to promote OS cells proliferation and invasion, and its oncogenic effects are mediated chiefly through targeting FOXO1.