title: Intracellular pathways mediating estrogen-induced cholangiocyte proliferation in the rat.
abstract: The aim of this study was to explore the intracellular signaling pathways involved in the stimulatory effects of estrogens on cholangiocyte proliferation. We investigated the tyrosine kinase-receptor pathway by evaluating the protein expression of total and phosphorylated mitogen-activated protein kinase (MAPK) isoform p44/p42 (e.g., extracellular signal-regulated kinase [ERK]1/2), the steroid-receptor coactivator Src and Shc (Src-homology/collagen protein). The study was performed in 3-week-old bile duct-ligated (BDL) rats, BDL rats treated with the antiestrogens, tamoxifen or Ici 182,780, and normal control rats. Proliferation was also evaluated in normal purified cholangiocytes treated with 17 beta estradiol in the presence or absence of tamoxifen, Ici 182,780, ERK, or Src inhibitors. After bile duct ligation, cholangiocyte proliferation was associated with a marked immunohistochemical nuclear positivity for phosphorylated (p)-ERK1/2, which was inhibited by in vivo treatment with tamoxifen or Ici 182,780. Protein expression of total and p-ERK1/2, and Shc in cholangiocytes isolated from BDL rats was markedly increased compared with controls and was inhibited by in vivo treatment with antiestrogens. In vitro, 17 beta estradiol-induced proliferation of isolated normal cholangiocyte was associated with increased (P <.01) protein expression of p-ERK1/2, Src, and Shc. Specific inhibitors of ER (Ici 182,780), ERK (U0125), and Src (PP2) inhibited in vitro 17 beta estradiol-induced cholangiocyte proliferation. In conclusion, this study showed that estrogens induced cholangiocyte proliferation by activating the Src/Shc/ERK pathway. This might suggest that pharmacologic modulation of ER, ERK, and/or Src could be proposed for the treatment of human pathology characterized by dysregulation of cholangiocyte proliferation.
authors.affiliation: Department of Clinical Medicine, Division of Gastroenterology, University of Rome, La Sapienza, Rome, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Alvaro
authors.forename: Paolo
authors.initials: P
authors.lastname: Onori
authors.forename: Veronica Drudi
authors.initials: VD
authors.lastname: Metalli
authors.forename: Gianluca
authors.initials: G
authors.lastname: Svegliati-Baroni
authors.forename: Franco
authors.initials: F
authors.lastname: Folli
authors.forename: Antonio
authors.initials: A
authors.lastname: Franchitto
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Alpini
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Mancino
authors.forename: Adolfo Francesco
authors.initials: AF
authors.lastname: Attili
authors.forename: Eugenio
authors.initials: E
authors.lastname: Gaudio
mesh_terms: D000818:Animals; D001653:Bile Ducts, Intrahepatic / Q000166:cytology* / Q000201:enzymology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D000077267:Fulvestrant; D066298:In Vitro Techniques; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D004965:Estrogen Antagonists; D013629:Tamoxifen; D000077267:Fulvestrant; D004958:Estradiol; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases