title: EpCAM-regulated intramembrane proteolysis induces a cancer stem cell-like gene signature in hepatitis B virus-infected hepatocytes.
abstract: Hepatocytes in which the hepatitis B virus (HBV) is replicating exhibit loss of the chromatin modifying polycomb repressive complex 2 (PRC2), resulting in re-expression of specific, cellular PRC2-repressed genes. Epithelial cell adhesion molecule (EpCAM) is a PRC2-repressed gene, normally expressed in hepatic progenitors, but re-expressed in hepatic cancer stem cells (hCSCs). Herein, we investigated the functional significance of EpCAM re-expression in HBV-mediated hepatocarcinogenesis.
  
  
  
  Employing molecular approaches (transfections, fluorescence-activated cell sorting, immunoblotting, qRT-PCR), we investigated the role of EpCAM-regulated intramembrane proteolysis (RIP) in HBV replicating cells in vitro, and in liver tumors from HBV X/c-myc mice and chronically HBV infected patients.
  
  
  
  EpCAM undergoes RIP in HBV replicating cells, activating canonical Wnt signaling. Transfection of Wnt-responsive plasmid expressing green fluorescent protein (GFP) identified a GFP+population of HBV replicating cells. These GFP+/Wnt+cells exhibited cisplatin- and sorafenib-resistant growth resembling hCSCs, and increased expression of pluripotency genes NANOG, OCT4, SOX2, and hCSC markers BAMBI, CD44 and CD133. These genes are referred as EpCAM RIP and Wnt-induced hCSC-like gene signature. Interestingly, this gene signature is also overexpressed in liver tumors of X/c-myc bitransgenic mice. Clinically, a group of HBV-associated hepatocellular carcinomas was identified, exhibiting elevated expression of the hCSC-like gene signature and associated with reduced overall survival post-surgical resection.
  
  
  
  The hCSC-like gene signature offers promise as prognostic tool for classifying subtypes of HBV-induced HCCs. Since EpCAM RIP and Wnt signaling drive expression of this hCSC-like signature, inhibition of these pathways can be explored as therapeutic strategy for this subtype of HBV-associated HCCs.
  
  
  
  In this study, we provide evidence for a molecular mechanism by which chronic infection by the hepatitis B virus results in the development of poor prognosis liver cancer. Based on this mechanism our results suggest possible therapeutic interventions.
authors.affiliation: Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, United States; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Saravana Kumar Kailasam
authors.initials: SK
authors.lastname: Mani
authors.affiliation: Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, United States; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, United States; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Diab
authors.affiliation: Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States; Purdue University Libraries, Purdue University, West Lafayette, IN 47907, United States.
authors.forename: Pete E
authors.initials: PE
authors.lastname: Pascuzzi
authors.affiliation: Centre de Recherche en Cancérologie de Lyon, UMR INSERM 1052 - CNRS 5286, Lyon Cedex 03, France.
authors.forename: Lydie
authors.initials: L
authors.lastname: Lefrançois
authors.affiliation: Centre de Recherche en Cancérologie de Lyon, UMR INSERM 1052 - CNRS 5286, Lyon Cedex 03, France.
authors.forename: Nadim
authors.initials: N
authors.lastname: Fares
authors.affiliation: Centre de Recherche en Cancérologie de Lyon, UMR INSERM 1052 - CNRS 5286, Lyon Cedex 03, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Bancel
authors.affiliation: Centre de Recherche en Cancérologie de Lyon, UMR INSERM 1052 - CNRS 5286, Lyon Cedex 03, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Merle
authors.affiliation: Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, United States; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States. Electronic address: andrisao@purdue.edu.
authors.forename: Ourania
authors.initials: O
authors.lastname: Andrisani
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular; D000071858:Epithelial Cell Adhesion Molecule; D006509:Hepatitis B; D006515:Hepatitis B virus; D022781:Hepatocytes; D006801:Humans; D008113:Liver Neoplasms; D051379:Mice; D014411:Neoplastic Stem Cells; D059748:Proteolysis
chemical_list: D000071858:Epithelial Cell Adhesion Molecule
keywords: BAMBI; CD133; CD44; EpCAM-regulated intramembrane proteolysis; Hepatitis B virus; Hepatocellular carcinoma; Pluripotency genes (NANOG, OCT4 and SOX2); SUZ12/polycomb repressive complex 2; Wnt signaling