title: Does the hepatitis B antigen HBx promote the appearance of liver cancer stem cells?
abstract: Hepatitis B virus (HBV) is a major etiologic agent of chronic liver disease and hepatocellular carcinoma (HCC). HBV-encoded X antigen, HBx, and pathways implicated in the self-renewal of stem cells contribute to HCC, but it is not clear whether HBx expression promotes "stemness." Thus, experiments were designed to test the hypothesis that HBx triggers malignant transformation by promoting properties that are characteristic of cancer stem cells (CSC). To test this hypothesis, HepG2 cells were stably transduced with HBx and then assayed for phenotypic and molecular characteristics of "stemness." The relationship between HBx and "stemness"-associated markers was also evaluated by immunohistochemical staining of liver and tumor tissue sections from HBV-infected patients. The results showed that Oct-4, Nanog, Klf-4, β-catenin, and epithelial cell adhesion molecule (EpCAM) were activated by HBx in vitro and in vivo. EpCAM was detected in the nuclei of human HCC cells from infected patients. HBx promotes "stemness" by activating β-catenin and epigenetic upregulation of miR-181, both of which target EpCAM. HBx expression was also associated with depressed levels of E-cadherin. Moreover, HBx stimulated cell migration, growth in soft agar, and spheroid formation. This work is the first to propose that HBV promotes "stemness" in the pathogenesis of HCC. HBx-associated upregulated expression of multiple "stemness" markers supports the hypothesis that HBx contributes to hepatocarcinogenesis, at least in part, by promoting changes in gene expression that are characteristics of CSCs.
authors.affiliation: Department of Biology, Sbarro Health Research Organization, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA. alla.arzumanyan@temple.edu
authors.forename: Alla
authors.initials: A
authors.lastname: Arzumanyan
authors.forename: Tiffany
authors.initials: T
authors.lastname: Friedman
authors.forename: Irene O L
authors.initials: IO
authors.lastname: Ng
authors.forename: Marcia M
authors.initials: MM
authors.lastname: Clayton
authors.forename: Zhaorui
authors.initials: Z
authors.lastname: Lian
authors.forename: Mark A
authors.initials: MA
authors.lastname: Feitelson
mesh_terms: D000328:Adult; D000368:Aged; D000951:Antigens, Neoplasm / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement; D044127:Epigenesis, Genetic; D000071858:Epithelial Cell Adhesion Molecule; D005260:Female; D006515:Hepatitis B virus / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism* / Q000821:virology; D008297:Male; D008875:Middle Aged; D000071317:Nanog Homeobox Protein; D014411:Neoplastic Stem Cells / Q000166:cytology*; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins; D051176:beta Catenin / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D000071858:Epithelial Cell Adhesion Molecule; D018398:Homeodomain Proteins; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; D051176:beta Catenin; C057628:hepatitis B virus X protein