title: HNF1α inhibition triggers epithelial-mesenchymal transition in human liver cancer cell lines.
abstract: BACKGROUND
  Hepatocyte Nuclear Factor 1α (HNF1α) is an atypical homeodomain-containing transcription factor that transactivates liver-specific genes including albumin, α-1-antitrypsin and α- and β-fibrinogen. Biallelic inactivating mutations of HNF1A have been frequently identified in hepatocellular adenomas (HCA), rare benign liver tumors usually developed in women under oral contraceptives, and in rare cases of hepatocellular carcinomas developed in non-cirrhotic liver. HNF1α-mutated HCA (H-HCA) are characterized by a marked steatosis and show activation of glycolysis, lipogenesis, translational machinery and mTOR pathway. We studied the consequences of HNF1α silencing in hepatic cell lines, HepG2 and Hep3B and we reproduced most of the deregulations identified in H-HCA.
  
  
  METHODS
  We transfected hepatoma cell lines HepG2 and Hep3B with siRNA targeting HNF1α and obtained a strong inhibition of HNF1α expression. We then looked at the phenotypic changes by microscopy and studied changes in gene expression using qRT-PCR and Western Blot.
  
  
  RESULTS
  Hepatocytes transfected with HNF1α siRNA underwent severe phenotypic changes with loss of cell-cell contacts and development of migration structures. In HNF1α-inhibited cells, hepatocyte and epithelial markers were diminished and mesenchymal markers were over-expressed. This epithelial-mesenchymal transition (EMT) was related to the up regulation of several EMT transcription factors, in particular SNAIL and SLUG. We also found an overexpression of TGFβ1, an EMT initiator, in both cells transfected with HNF1α siRNA and H-HCA. Moreover, TGFβ1 expression is strongly correlated to HNF1α expression in cell models, suggesting regulation of TGFβ1 expression by HNF1α.
  
  
  CONCLUSIONS
  Our results suggest that HNF1α is not only important for hepatocyte differentiation, but has also a role in the maintenance of epithelial phenotype in hepatocytes.
authors.affiliation: Inserm U674 Génomique fonctionnelle des tumeurs solides, Paris, France.
authors.forename: Laura
authors.initials: L
authors.lastname: Pelletier
authors.forename: Sandra
authors.initials: S
authors.lastname: Rebouissou
authors.forename: Danijela
authors.initials: D
authors.lastname: Vignjevic
authors.forename: Paulette
authors.initials: P
authors.lastname: Bioulac-Sage
authors.forename: Jessica
authors.initials: J
authors.lastname: Zucman-Rossi
mesh_terms: D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D004847:Epithelial Cells / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D015870:Gene Expression; D020868:Gene Silencing; D056945:Hep G2 Cells; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000037:antagonists & inhibitors* / Q000235:genetics; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics*; D009154:Mutation; D010641:Phenotype; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000235:genetics
chemical_list: D051538:Hepatocyte Nuclear Factor 1-alpha; D053773:Transforming Growth Factor beta1