title: Subset of Suz12/PRC2 target genes is activated during hepatitis B virus replication and liver carcinogenesis associated with HBV X protein.
abstract: Chronic hepatitis B virus (HBV) infection is a major risk factor for developing liver cancer, and the HBV X protein (pX) has been implicated as a cofactor in hepatocyte transformation. We have shown that HBV replication as well as in vitro transformation by pX are associated with induction of the mitotic polo-like kinase 1 (Plk1) and down-regulation of the chromatin remodeling components Suz12 and Znf198. Herein, we demonstrate the same inverse relationship between Plk1 and Suz12/Znf198 in liver tumors from X/c-myc bitransgenic mice and woodchuck hepatitis virus (WHV)-infected woodchucks. Employing these animal models and the HBV replicating HepAD38 cells we examined the effect of Suz12/Znf198 down-regulation on gene expression. Genes analyzed include hepatic cancer stem cell markers BAMBI, DKK1,2, DLK1, EpCAM, MYC, and proliferation genes CCNA1, CCND2, IGFII, MCM4-6, PLK1, RPA2, and TYMS. Suz12 occupancy at the promoters of BAMBI, CCND2, DKK2, DLK1, EpCAM, and IGFII was demonstrated by chromatin immunoprecipitation in untransformed hepatocytes, but was markedly reduced in pX-transformed and Suz12 knockdown cells. Accordingly, we refer to these genes as "Suz12 repressed" genes in untransformed hepatocytes. The Suz12 repressed genes and proliferation genes were induced in HBV-replicating HepAD38 cells and, interestingly, they exhibited distinct expression profiles during hepatocellular carcinoma (HCC) progression in X/c-myc bitransgenics. Specifically, CCND2, EpCAM, and IGFII expression was elevated at the proliferative and preneoplastic stages in X/c-myc bitransgenic livers, whereas BAMBI and PLK1 were overexpressed in hepatic tumors from X/c-myc bitransgenics and WHV-infected woodchucks. Importantly, most of these genes were selectively up-regulated in HBV-induced HCCs.
  
  
  CONCLUSIONS
  The distinct expression profile of the identified Suz12 repressed genes in combination with the proliferation genes hold promise as biomarkers for progression of chronic HBV infection to HCC.
authors.affiliation: Department of Basic Medical Sciences and Purdue University Center for Cancer Research, West Lafayette, IN 47907-2026, USA.
authors.forename: Leo L
authors.initials: LL
authors.lastname: Studach
authors.forename: Stephan
authors.initials: S
authors.lastname: Menne
authors.forename: Stefano
authors.initials: S
authors.lastname: Cairo
authors.forename: Marie Annick
authors.initials: MA
authors.lastname: Buendia
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Hullinger
authors.forename: Lydie
authors.initials: L
authors.lastname: Lefrançois
authors.forename: Philippe
authors.initials: P
authors.lastname: Merle
authors.forename: Ourania M
authors.initials: OM
authors.lastname: Andrisani
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000821:virology*; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D015536:Down-Regulation; D015967:Gene Expression Regulation, Viral; D006515:Hepatitis B virus / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000235:genetics / Q000503:physiopathology; D022781:Hepatocytes / Q000473:pathology; D008113:Liver Neoplasms / Q000235:genetics / Q000821:virology*; D008392:Marmota; D051379:Mice; D008822:Mice, Transgenic; D063151:Polycomb Repressive Complex 2 / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D011897:Random Allocation; D012680:Sensitivity and Specificity; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation; D054334:Viral Regulatory and Accessory Proteins; D014779:Virus Replication / Q000235:genetics; D000097869:Polo-Like Kinase 1
chemical_list: D018797:Cell Cycle Proteins; D063151:Polycomb Repressive Complex 2; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; D000097869:Polo-Like Kinase 1; C494163:Suz12 protein, mouse; C057628:hepatitis B virus X protein