title: Progesterone-induced inhibition of growth and differential regulation of gene expression in PRA- and/or PRB-expressing endometrial cancer cell lines.
abstract: OBJECTIVE
  Progesterone plays an important role in controlling proliferation and differentiation of the human endometrium. Because there are two progesterone receptor isoforms (PRA and PRB), it was important to generate tools to be able to study the role of these two progesterone receptors separately.
  
  
  METHODS
  Using stable transfection techniques, both human progesterone receptor isoforms (hPRA and hPRB) were reintroduced into a hPR-negative subclone of the well-differentiated endometrial cancer cell line Ishikawa. Several Ishikawa subcell lines were constructed, each expressing different levels of hPRA, hPRB, or hPRA and hPRB, respectively.
  
  
  RESULTS
  These Ishikawa subcell lines showed a marked progesterone-induced growth inhibition with induction of apoptosis after long-term culture in the presence of hormone. Upon measuring gene regulation, a clear difference in regulation of expression of the selected genes by progesterone treatment was observed between the PRA-, PRB-, or PRA/B-expressing cell lines. Integrin beta4 (ITGB4) was only regulated in PRA-expressing cells; amphiregulin was highly regulated in PRB-expressing cells; insulin-like growth factor binding protein 3 (IGFBP3) was only regulated in PRB- and PRA/B-expressing cells; and metallothionein 1L (MT1L) was highly regulated in PRA/B-expressing cells. Interestingly, based on literature data, these genes can be implicated in induction of apoptosis, but are modulated here in such a way that suggests induction of resistance against apoptosis.
  
  
  CONCLUSIONS
  Reintroduction of PRs into Ishikawa cells rescued progesterone responsiveness in these cells. Furthermore, using these human endometrial cancer subcell lines, clear and distinct functional differences between the PR isoforms were observed.
authors.affiliation: Department of Obstetrics and Gynecology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Ellen
authors.initials: E
authors.lastname: Smid-Koopman
authors.forename: Liesbeth C M
authors.initials: LC
authors.lastname: Kuhne
authors.forename: Eline E
authors.initials: EE
authors.lastname: Hanekamp
authors.forename: Susanne C J P
authors.initials: SC
authors.lastname: Gielen
authors.forename: Petra E
authors.initials: PE
authors.lastname: De Ruiter
authors.forename: J Anton
authors.initials: JA
authors.lastname: Grootegoed
authors.forename: Theo J M
authors.initials: TJ
authors.lastname: Helmerhorst
authors.forename: Curt W
authors.initials: CW
authors.lastname: Burger
authors.forename: Albert O
authors.initials: AO
authors.lastname: Brinkmann
authors.forename: Frans J
authors.initials: FJ
authors.lastname: Huikeshoven
authors.forename: Leen J
authors.initials: LJ
authors.lastname: Blok
mesh_terms: D017209:Apoptosis; D002454:Cell Differentiation; D049109:Cell Proliferation; D016889:Endometrial Neoplasms / Q000235:genetics* / Q000473:pathology*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D011374:Progesterone / Q000502:physiology*; D020033:Protein Isoforms; D011980:Receptors, Progesterone / Q000096:biosynthesis*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D020033:Protein Isoforms; D011980:Receptors, Progesterone; C101118:progesterone receptor A; C097314:progesterone receptor B; D011374:Progesterone