title: Progesterone inhibition of Wnt/beta-catenin signaling in normal endometrium and endometrial cancer.
abstract: OBJECTIVE
  Wnt signaling regulates the fine balance between stemness and differentiation. Here, the role of Wnt signaling to maintain the balance between estrogen-induced proliferation and progesterone-induced differentiation during the menstrual cycle, as well as during the induction of hyperplasia and carcinogenesis of the endometrium, was investigated.
  
  
  METHODS
  Endometrial gene expression profiles from estradiol (E(2)) and E(2) + medroxyprogesterone acetate-treated postmenopausal patients were combined with profiles obtained during the menstrual cycle (PubMed; GEO DataSets). Ishikawa cells were transfected with progesterone receptors and Wnt inhibitors dickkopf homologue 1 (DKK1) and forkhead box O1 (FOXO1), measuring Wnt activation. Expression of DKK1 and FOXO1 was inhibited by use of sequence-specific short hairpins. Furthermore, patient samples (hormone-treated endometria, hyperplasia, and endometrial cancer) were stained for Wnt activation using nuclear beta-catenin and CD44.
  
  
  RESULTS
  In vivo, targets and components of the Wnt signaling pathway (among them DKK1 and FOXO1) are regulated by E(2) and progesterone. In Wnt-activated Ishikawa cells, progesterone inhibits Wnt signaling by induction of DKK1 and FOXO1. Furthermore, using siRNA-mediated knockdown of both DKK1 and FOXO1, progesterone inhibition of Wnt signaling was partly circumvented. Subsequently, immunohistochemical analysis of the Wnt target gene CD44 showed that progesterone acted as an inhibitor of Wnt signaling in hyperplasia and in well-differentiated endometrial cancer.
  
  
  CONCLUSIONS
  Progesterone induction of DKK1 and FOXO1 results in inhibition of Wnt signaling in the human endometrium. This Wnt inhibitory effect of progesterone is likely to play a rate-limiting role in the maintenance of endometrial homeostasis and, on its loss, in tumor onset and progression toward malignancy.
authors.affiliation: Department of Obstetrics and Gynecology, Josephine Nefkens Institute, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors.forename: Yongyi
authors.initials: Y
authors.lastname: Wang
authors.forename: Payman
authors.initials: P
authors.lastname: Hanifi-Moghaddam
authors.forename: Eline E
authors.initials: EE
authors.lastname: Hanekamp
authors.forename: Helenius J
authors.initials: HJ
authors.lastname: Kloosterboer
authors.forename: Patrick
authors.initials: P
authors.lastname: Franken
authors.forename: Jos
authors.initials: J
authors.lastname: Veldscholte
authors.forename: Helena C
authors.initials: HC
authors.lastname: van Doorn
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Ewing
authors.forename: J Julie
authors.initials: JJ
authors.lastname: Kim
authors.forename: J Anton
authors.initials: JA
authors.lastname: Grootegoed
authors.forename: Curt W
authors.initials: CW
authors.lastname: Burger
authors.forename: Riccardo
authors.initials: R
authors.lastname: Fodde
authors.forename: Leen J
authors.initials: LJ
authors.lastname: Blok
mesh_terms: D016889:Endometrial Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004717:Endometrium / Q000187:drug effects* / Q000378:metabolism*; D004967:Estrogens / Q000378:metabolism; D005260:Female; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: C501126:DKK1 protein, human; D004967:Estrogens; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D036341:Intercellular Signaling Peptides and Proteins; D051153:Wnt Proteins; D051176:beta Catenin; D011374:Progesterone