miR-155 promotes the growth of osteosarcoma in a HBP1-dependent mechanism.

Osteosarcoma (OS) is a type of malignant tumor arising from soft-tissues of bone and displays poor prognosis in most cases. However, the molecular mechanism by which OS initiates and progresses is still not completely elucidated. miR-155 has been shown to be overexpressed in OS specimen and cell lines. Our study is intended to explore the role of miR-155 in OS etiology. The data confirmed that miR-155 abundance is higher in OS samples than non-cancerous bone tissue. Inhibition of miR-155 suppressed the proliferation of OS cells and cell cycle progression in vitro, and the growth of OS xenografts in vivo. Wnt pathway was suppressed in OS cells by miR-155 inhibitors. HMG-box transcription factor 1 (HBP1), a strong Wnt pathway suppressor, was found to be a target of miR-155. Restoration of HBP1 abolished the effect of miR-155 on OS cells. Finally, miR-155 levels in OS tissues and serum are both inversely associated with the survival of OS patients. Collectively, miR-155 was identified to be among the list of OS-related oncogenic miRNAs, and HBP1-mediated Wnt signaling is involved with the role of miR-155 in OS progression.