miR-519 suppresses nasopharyngeal carcinoma cell proliferation by targeting oncogene URG4/URGCP.

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumor in Southeast Asia, its regulatory mechanism is still to be understood. miR-519 inhibits the progression of several tumors, including cervical cancer, ovarian cancer and gastric cancer. But its role in NPC hasn't been studied. In present study, we found miR-519 was downregulated in NPC cells, its overexpression inhibited NPC cell proliferation and arrested cell cycle at G0/G1 phase, while its knockdown promoted NPC cell proliferation and cell cycle progression. An oncogene URG4/URGCP (upregulated gene-4/upregulator of cell proliferation) was the target of miR-519, URG4 was upregulated in NPC cells, miR-519 inhibited URG4 expression by directly binding to the 3'UTR of URG4. miR-519 inhibited Cyclin D1 expression and the phosphorylation level of Rb, and increased p21 and p27 expression, confirming miR-519 blocked G1/S transition. Moreover, miR-519 level was negative correlated with URG4 level in NPC tissues. In summary, we found miR-519 NPC cell proliferation by inhibiting URG4.