title: Regulation of amphiregulin gene expression by β-catenin signaling in human hepatocellular carcinoma cells: a novel crosstalk between FGF19 and the EGFR system.
abstract: Hepatocellular carcinoma (HCC) is the most prevalent liver tumor and a deadly disease with limited therapeutic options. Dysregulation of cell signaling pathways is a common denominator in tumorigenesis, including hepatocarcinogenesis. The epidermal growth factor receptor (EGFR) signaling system is commonly activated in HCC, and is currently being evaluated as a therapeutic target in combination therapies. We and others have identified a central role for the EGFR ligand amphiregulin (AR) in the proliferation, survival and drug resistance of HCC cells. AR expression is frequently up-regulated in HCC tissues and cells through mechanisms not completely known. Here we identify the β-catenin signaling pathway as a novel mechanism leading to transcriptional activation of the AR gene in human HCC cells. Activation of β-catenin signaling, or expression of the T41A β-catenin active mutant, led to the induction of AR expression involving three specific β-catenin-Tcf responsive elements in its proximal promoter. We demonstrate that HCC cells expressing the T41A β-catenin active mutant show enhanced proliferation that is dependent in part on AR expression and EGFR signaling. We also demonstrate here a novel cross-talk of the EGFR system with fibroblast growth factor 19 (FGF19). FGF19 is a recently identified driver gene in hepatocarcinogenesis and an activator of β-catenin signaling in HCC and colon cancer cells. We show that FGF19 induced AR gene expression through the β-catenin pathway in human HCC cells. Importantly, AR up-regulation and EGFR signaling participated in the induction of cyclin D1 and cell proliferation elicited by FGF19. Finally, we demonstrate a positive correlation between FGF19 and AR expression in human HCC tissues, therefore supporting in clinical samples our experimental observations. These findings identify the AR/EGFR system as a key mediator of FGF19 responses in HCC cells involving β-catenin signaling, and suggest that combined targeting of FGF19 and AR/EGFR may enhance therapeutic efficacy.
authors.affiliation: Division of Hepatology and Gene Therapy, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain.
authors.forename: Maria U
authors.initials: MU
authors.lastname: Latasa
authors.forename: Fabiana
authors.initials: F
authors.lastname: Salis
authors.forename: Raquel
authors.initials: R
authors.lastname: Urtasun
authors.forename: Oihane
authors.initials: O
authors.lastname: Garcia-Irigoyen
authors.forename: Maria
authors.initials: M
authors.lastname: Elizalde
authors.forename: Iker
authors.initials: I
authors.lastname: Uriarte
authors.forename: Monica
authors.initials: M
authors.lastname: Santamaria
authors.forename: Francesco
authors.initials: F
authors.lastname: Feo
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Pascale
authors.forename: Jesús
authors.initials: J
authors.lastname: Prieto
authors.forename: Carmen
authors.initials: C
authors.lastname: Berasain
authors.forename: Matías A
authors.initials: MA
authors.lastname: Avila
mesh_terms: D066258:Amphiregulin; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019938:Cyclin D1 / Q000378:metabolism; D066255:EGF Family of Proteins; D066246:ErbB Receptors / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D011379:Prognosis; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000378:metabolism; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: C587848:AREG protein, human; D066258:Amphiregulin; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D066255:EGF Family of Proteins; C117476:FGF19 protein, human; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors; D051176:beta Catenin; D019938:Cyclin D1; D005346:Fibroblast Growth Factors; D066246:ErbB Receptors