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

PLoS One. 2012;7(7):e40607. doi: 10.1371/journal.pone.0040607. Epub 2012 Jul 16.

Abstract

Objective: 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.

Design: 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.

Results: 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.

Conclusions: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / pathology*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cell Transformation, Neoplastic / drug effects
  • Cell Transformation, Neoplastic / pathology*
  • Cyclin D1 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p27 / metabolism
  • Cyclin-Dependent Kinases / metabolism
  • Down-Regulation* / drug effects
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors / genetics*
  • Forkhead Transcription Factors / metabolism
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Knockdown Techniques
  • Gene Silencing / drug effects
  • Humans
  • Kaplan-Meier Estimate
  • Liver Neoplasms / genetics
  • Liver Neoplasms / pathology*
  • Male
  • Mice
  • Mice, SCID
  • Neoplasm Proteins / metabolism*
  • Prognosis
  • Protein Kinase Inhibitors / pharmacology
  • Transcription, Genetic / drug effects
  • Up-Regulation* / drug effects

Substances

  • CCND1 protein, human
  • Cyclin-Dependent Kinase Inhibitor p21
  • FOXO3 protein, human
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors
  • Neoplasm Proteins
  • Protein Kinase Inhibitors
  • URGCP protein, human
  • Cyclin D1
  • Cyclin-Dependent Kinase Inhibitor p27
  • Cyclin-Dependent Kinases