title: The tumor suppressor gastrokine-1 is expressed in placenta and contributes to the regulation of trophoblast migration.
abstract: BACKGROUND
  Gastrokine-1 (GKN1) is a secreted auto-/paracrine protein, described to be expressed in the gastric mucosa. In gastric cancers GKN1 expression is commonly down-regulated. While current research focusses on the exploration of tumor-suppressive properties of GKN1 with regard to its potential clinical use in the treatment of gastroenterologic tumor disease, nothing is known about GKN1 expression and function in other organ systems. We investigated GKN1 expression in placental tissue and cells.
  
  
  METHODS
  GKN1 was localized using immunohistochemistry in first and third trimester placental tissue, hydatidiform moles and various gestational trophoblastic neoplasias. We determined the expression of GKN1 in immunomagnetic bead-separated term placental cells and in choriocarcinoma cell lines. The role of GKN1 for JEG-3 migration was studied using live cell imaging. E-cadherin, MMP-2 and -9, TIMP-1 and -2, as well as urokinase (uPA) expression levels were determined.
  
  
  RESULTS
  GKN1 is expressed in healthy third trimester placentas. Its expression is specifically limited to the extravillous trophoblast (EVT). GKN1 expression is significantly reduced in choriocarcinoma cell lines and gestational trophoblastic neoplasias. GKN1 attenuates the migration of JEG-3 choriocarcinoma cells in vitro, possibly via AKT-mediated induction of E-cadherin. GKN1 treatment reduced MMP-9 expression in JEG-3.
  
  
  CONCLUSIONS
  Besides its role in gastric physiology our results clearly indicate regulatory functions of GKN1 in the EVT at the feto-maternal interface during pregnancy. Based on our findings in the JEG-3 choriocarcinoma cell line, an auto-/paracrine role of GKN1 for EVT motility and villous anchorage at the basal plate is conceivable. Thus, the tumor suppressor GKN1 is expressed in placental EVT and might contribute to the regulation of EVT migration/invasion.
authors.affiliation: Department of Pediatrics and Adolescent Medicine, University of Erlangen-Nürnberg, Loschgestrasse 15, 91054 Erlangen, Germany. Electronic address: fabian.fahlbusch@uk-erlangen.de.
authors.forename: F B
authors.initials: FB
authors.lastname: Fahlbusch
authors.forename: M
authors.initials: M
authors.lastname: Ruebner
authors.forename: H
authors.initials: H
authors.lastname: Huebner
authors.forename: G
authors.initials: G
authors.lastname: Volkert
authors.forename: C
authors.initials: C
authors.lastname: Zuern
authors.forename: F
authors.initials: F
authors.lastname: Thiel
authors.forename: M
authors.initials: M
authors.lastname: Koch
authors.forename: C
authors.initials: C
authors.lastname: Menendez-Castro
authors.forename: D L
authors.initials: DL
authors.lastname: Wachter
authors.forename: A
authors.initials: A
authors.lastname: Hartner
authors.forename: W
authors.initials: W
authors.lastname: Rascher
mesh_terms: D015703:Antigens, CD; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement; D002478:Cells, Cultured; D002822:Choriocarcinoma / Q000378:metabolism / Q000473:pathology; D015536:Down-Regulation; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D006828:Hydatidiform Mole / Q000378:metabolism / Q000473:pathology; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D036361:Peptide Hormones / Q000235:genetics / Q000378:metabolism*; D010920:Placenta / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011263:Pregnancy Trimester, Third; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D018245:Trophoblastic Tumor, Placental Site / Q000378:metabolism / Q000473:pathology; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D014594:Uterine Neoplasms / Q000378:metabolism / Q000473:pathology
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; C477000:GKN1 protein, human; D009363:Neoplasm Proteins; D036361:Peptide Hormones; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9
keywords: E-cadherin; Gastrokine-1; Gestational trophoblastic neoplasias; JEG-3; MMP-9; Placenta; Trefoil factor