Ovarian epithelial inclusion cysts in chronically superovulated CD1 and Smad2 dominant-negative mice

Endocrinology. 2007 Aug;148(8):3595-604. doi: 10.1210/en.2007-0030. Epub 2007 Apr 12.


Chronic ovulation as a contributing factor for the development of epithelial ovarian cancer in women has long been an outstanding hypothesis. To test the incessant ovulation hypothesis, mice were superovulated using weekly ip injections of pregnant mare serum gonadotropin (5 IU/animal), followed 48 h later by human chorionic gonadotropin (5 IU/animal). Wild-type CD1 mice were used along with CD1 mice expressing a Smad2 dominant-negative (Smad2DN) transgene under the control of the Müllerian inhibiting substance promoter that targets expression to the ovary and enhances cyst formation. After chronic injections, ovaries were analyzed from animals 6 months of age for the total adjusted number of cysts, cyst area, cyst location, and key signaling pathways. All observed cysts were confirmed to be of epithelial origin. The number of cysts was not significantly different between superovulated and control mice in either the wild-type or Smad2DN groups. However, the combination of the Smad2DN transgene and superovulation resulted in an increase in cyst formation compared with normal littermates that were unstimulated. Rapid proliferation of the cells lining the cysts was detected using bromodeoxyuridine and phospho-histone 3 immunohistochemistry but was not different in the ovarian surface epithelium or in the cyst lining between groups. These data suggest that chronic superovulation in Smad2DN mice results in a higher incidence of cyst formation compared with unstimulated controls, but the epithelial lined cysts did not progress to cancer over the course of this study.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Activins / metabolism
  • Animals
  • Cell Division / physiology
  • Chronic Disease
  • Epithelial Cells / pathology
  • Epithelial Cells / physiology
  • Female
  • Gonadotropins, Equine / pharmacology
  • Mice
  • Mice, Inbred Strains
  • Mice, Transgenic
  • Ovarian Cysts / complications
  • Ovarian Cysts / pathology
  • Ovarian Cysts / physiopathology*
  • Ovarian Neoplasms / etiology
  • Ovarian Neoplasms / pathology
  • Ovarian Neoplasms / physiopathology
  • Ovulation / physiology*
  • Phosphorylation
  • Signal Transduction / physiology
  • Smad2 Protein / genetics*
  • Smad2 Protein / metabolism*
  • Superovulation / drug effects
  • Superovulation / physiology*
  • Transforming Growth Factor beta / metabolism


  • Gonadotropins, Equine
  • Smad2 Protein
  • Smad2 protein, mouse
  • Transforming Growth Factor beta
  • Activins