Upregulator of cell proliferation predicts poor prognosis in hepatocellular carcinoma and contributes to hepatocarcinogenesis by downregulating FOXO3a.

• Main Authors: Chan Xie, Li-bing Song, Jue-heng Wu, Jun Li, Jing-ping Yun, Jia-ming Lai, Dong-ying Xie, Bing-liang Lin, Yun-fei Yuan, Mengfeng Li, Zhi-liang Gao
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2012-01-01
• Series: PLoS ONE
• Online Access: https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22815774/?tool=EBI

<h4>Objective</h4>The goal of the present study was to investigate the potential correlation between the expression level of upregulator of cell proliferation (URGCP/URG4) and the prognosis of hepatocellular carcinoma (HCC), and to examine the biological function of URGCP/URG4 in the progression of HCC, to better understand its underlying molecular mechanism in hepatic tumorigenesis.<h4>Design</h4>URGCP/URG4 expression was analyzed in 15 HCC cell lines, in 278 archived paraffin-embedded HCC sections, and in 10 pairs of fresh HCC tumor and para-tumor non-cancerous tissues using immunohistochemistry (IHC) and Western blotting analysis (WB). The effect of URGCP/URG4 on cell proliferation and tumorigenesis was examined in vitro and in vivo. WB and luciferase reporter analyses were performed to identify the effects of URGCP/URG4-overexpression or -knockdown on expression of cell cycle regulators and transcriptional activity of FOXO3a.<h4>Results</h4>IHC results revealed an upregulation of URGCP/URG4 in all HCC cell lines and fresh HCC samples as compared with normal liver cells and para-tumor tissues, respectively. URGCP/URG4 was also expressed at a high level in 122 of the 278 (43.8%) archived HCC specimens. The expression level of URGCP/URG4 was significantly correlated with clinical staging and poor patient survival of HCC in the study cohort, and in various clinical subgroups. Strikingly, ectopic expression of URGCP/URG4 induced proliferation and anchorage-independent growth of HCC cells, while silencing of URGCP/URG4 had the opposite effect. Furthermore, URGCP/URG4 overexpression in HCC cells increased cellular entry into the G1/S transitional phase, associated with downregulation of p27(Kip1) and p21(Cip1) and upregulation of cyclin D1. These effects were accompanied by enhanced Akt activity and reduced FOXO3a transcriptional activity.<h4>Conclusions</h4>URGCP/URG4 plays an important role in promoting proliferation and tumorigenesis of HCC and may represent a novel prognostic biomarker and therapeutic target for this disease.