Downregulation of miR-16 via URGCP pathway contributes to glioma growth

Experimental and clinical evidence points to a critical role of Upregulator of cell proliferation (URGCP/URG4) in controlling the progression of multiple tumors. However, the oncogenic role of URGCP in glioma still remains elusive. In this study we tried to investigate the oncogenic roles and molecular mechanisms of URGCP in glioma. We found that the levels of URGCP were upregulated in glioma, and that the high-levels of URGCP indicated a worse prognosis in glioma patients. URGCP and miR-16 are critical for glioma growth: silencing URGCP (shURGCP) inhibited glioma growth, while, the shURGCP-mediated proliferative inhibition could be recovered by antagonizing miR-16 (anta-miR-16) in vivo and in vitro. Mechanically, URGCP repressed miR-16 expression via activating NF-κB/c-myc pathway in glioma; Cyclins D1 and Cyclin E1 were identified as the direct targets of miR-16, thus, URGCP-mediated miR-16 downregulation accelerated cell proliferation by upregulating Cyclin D1 and Cyclin E1 expression. All these results suggested that URGCP accelerates glioma growth through the NF-κB/c-myc/miR-16/Cyclin D1/E1 pathway, and both URGCP and miR-16 function as a novel cell cycle regulators in glioma and could be considered as potential targets for glioma therapy.