title: Membrane-initiated effects of progesterone on proliferation and activation of VEGF in breast cancer cells.
abstract: OBJECTIVE
  Progesterone influences mammary gland development and probably breast cancer tumorigenesis and functions by regulating a broad spectrum of physiological processes. We investigated receptor membrane-initiated actions of progesterone in MCF-7 breast cancer cells via progesterone receptor membrane component 1 (PGRMC1).
  
  
  METHODS
  The expression of PGRMC1 in breast cancer was verified by immune fluorescent analysis of paraffin sections. MCF-7 cells were transfected with PGRMC1 (wild type) or PGRMC1 variants. These cells were stimulated with a membrane-impermeable progesterone (P4) conjugate (P4-BSA-fluorescein isothiocyanate, P4-BSA-FITC, 10(-6) mol/l) or unconjugated progesterone (P4, 10(-6) mol/l) in the presence or absence of the progesterone receptor blocker RU-486 (10(-6) mol/l). Additionally, the effects on the expression of vascular endothelial growth factor A (VEGF-A) were determined using quantitative real-time polymerase chain reaction.
  
  
  RESULTS
  PGRMC1 is perinuclearly localized in breast cancer cells. Western Blot analysis suggests that PGRMC1 is phosphorylated at serine 180. MCF-7-PGRMC1 (S180A) cells show an approximately 35% increase in proliferation after incubation with P4-BSA-FITC compared to MCF-7 control and MCF-7-PGRMC1 (wild type) cells. This effect cannot be blocked by RU-486. P4 reduced proliferation of MCF-7-PGRMC1 cells by approximately 10% compared to untreated controls. P4-BSA-FITC treatment led to a roughly three-fold activation of VEGF-A gene expression compared to MCF-7 cells.
  
  
  CONCLUSIONS
  PGRMC1 is expressed in breast cancer tissue and mediates an RU-486-independent proliferative signal. It might also contribute to VEGF-induced neovascularization in tumor tissue. Thus, screening for PGRMC1 expression might be of interest to identify women with a higher expression of PGRMC1 and who might thus be susceptible for breast cancer development under hormone replacement therapy.
authors.affiliation: Department of Obstetrics and Gynecology, University of Tuebingen, Tuebingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Neubauer
authors.forename: G
authors.initials: G
authors.lastname: Adam
authors.forename: H
authors.initials: H
authors.lastname: Seeger
authors.forename: A O
authors.initials: AO
authors.lastname: Mueck
authors.forename: E
authors.initials: E
authors.lastname: Solomayer
authors.forename: D
authors.initials: D
authors.lastname: Wallwiener
authors.forename: M A
authors.initials: MA
authors.lastname: Cahill
authors.forename: T
authors.initials: T
authors.lastname: Fehm