title: Simvastatin maintains osteoblastic viability while promoting differentiation by partially regulating the expressions of estrogen receptors α.
abstract: BACKGROUND
  Statin is a specific inhibitor of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase, a rate-limiting enzyme involved in the cholesterol synthesis pathway. In addition to their long-known efficacy for lowering cholesterol, statins have also been reported to possess anabolic effects on bone. Simvastatin is reported to increase cancellous bone volume, bone formation rate, and cancellous bone compressive strength in vivo.
  
  
  METHODS
  In this report, the effects of simvastatin on osteoprecursor cells were evaluated. The effect on cell viability was determined by MTT assay, whereas differentiation and mineralization were examined using an alkaline phosphatase activity (ALP) test and alizarin red-S staining. Protein expressions related to bone formation, such as estrogen receptor-alpha (ER-α) and beta (ER-β), were evaluated by using a Western blot analysis. To assess whether the osteoinductive effect of simvastatin occurs via estrogen receptor pathway, estrogen receptor agonist (E2) and antagonists (ICI 182,780) were applied to the cultures.
  
  
  RESULTS
  Cultures grown in the presence of simvastatin exhibited an increased value for ALP activity and mineralization. The results of the Western blot analysis indicated that the addition of simvastatin up-regulated ER-α and ER-β expression with a statistically significant difference in ER-α expression. Treatment of E2 led to an increase of the ALP activity and mineralization, but addition of the estrogen receptor antagonist ICI 182,780 revealed a decrease in both values.
  
  
  CONCLUSIONS
  Based on these findings, it was concluded that simvastatin could produce positive effects on both the differentiation and mineralization of osteoprecursor cells. Our results also suggested that osteoinductive effects of simvastatin were achieved through ER pathway via the increase of ER-α expression.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109-1065, USA.
authors.forename: Jun-Beom
authors.initials: JB
authors.lastname: Park
authors.forename: Huina
authors.initials: H
authors.lastname: Zhang
authors.forename: Chia-Ying
authors.initials: CY
authors.lastname: Lin
authors.forename: Chong Pyoung
authors.initials: CP
authors.lastname: Chung
authors.forename: Youngro
authors.initials: Y
authors.lastname: Byun
authors.forename: Yoon Shin
authors.initials: YS
authors.lastname: Park
authors.forename: Victor C
authors.initials: VC
authors.lastname: Yang
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002113:Calcification, Physiologic / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000378:metabolism; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D019821:Simvastatin / Q000494:pharmacology*
chemical_list: D000924:Anticholesteremic Agents; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D019821:Simvastatin; D000469:Alkaline Phosphatase