title: Metformin: direct inhibition of rat ovarian theca-interstitial cell proliferation.
abstract: OBJECTIVE
  To determine whether metformin has direct effects on ovarian theca-interstitial (T-I) cell proliferation through activation of adenosine monophosphate-activated protein kinase (AMPK).
  
  
  METHODS
  In vitro experimental study.
  
  
  METHODS
  Academic medical center laboratory.
  
  
  METHODS
  Immature Sprague-Dawley female rats.
  
  
  METHODS
  Ovarian T-I cells were isolated, purified, and cultured in the absence (control) or presence of insulin (1 μg/mL) with or without metformin or other activators/inhibitors of AMPK (AICAR, compound C).
  
  
  METHODS
  Proliferation assessed by determination of expression levels of proteins involved in cell cycle progression, cyclin D3, and cyclin-dependent kinase 4 (CDK4) with Western blot analysis, and determination of DNA synthesis with bromodeoxyuridine (BrdU) incorporation assay; activation of AMPK, Erk1/2, and S6K1 determined by Western blot analysis with the use of antibodies specific for the phosphorylated (activated) forms.
  
  
  RESULTS
  Metformin inhibited insulin-induced ovarian T-I cell proliferation and the up-regulation of the cell cycle regulatory proteins, cyclin D3 and CDK4. Metformin independently activated AMPK in a dose-dependent manner. Treatment with metformin inhibited insulin-induced activation of Erk1/2 and S6K1. This effect was reversed with the addition of compound C, a known AMPK inhibitor.
  
  
  CONCLUSIONS
  Metformin directly inhibits proliferation of ovarian T-I cells via an AMPK-dependent mechanism. These findings further validate the potential benefits of metformin in the treatment of conditions associated with hyperinsulinemia and excessive growth of ovarian T-I cells (such as polycystic ovary syndrome).
authors.affiliation: Department of Obstetrics and Gynecology, University of Michigan Medical School, Ann Arbor, Michigan, USA. matwill@med.umich.edu
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Will
authors.forename: Murugesan
authors.initials: M
authors.lastname: Palaniappan
authors.forename: Helle
authors.initials: H
authors.lastname: Peegel
authors.forename: Pradeep
authors.initials: P
authors.lastname: Kayampilly
authors.forename: K M J
authors.initials: KM
authors.lastname: Menon
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000818:Animals; D059447:Cell Cycle Checkpoints / Q000187:drug effects / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D007004:Hypoglycemic Agents / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008687:Metformin / Q000494:pharmacology*; D010053:Ovary / Q000166:cytology / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D013799:Theca Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin; D019893:Ribosomal Protein S6 Kinases; C526901:Rps6kb1 protein, rat; D055372:AMP-Activated Protein Kinases