title: Simvastatin induces apoptosis and disruption of the actin cytoskeleton in human dental pulp cells and periodontal ligament fibroblasts.
abstract: OBJECTIVE
  Simvastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, and widely used as cholesterol-lowering agent, has been suggested for its beneficial effects on alveolar bone formation, regeneration of dental pulp tissue and periodontal ligament. High doses of simvastatin appear to induce apoptosis in several cell types, but little is known about its possible effect on tooth-associated cells. Therefore, the effects of simvastatin were studied on apoptosis and cell morphology of human dental pulp cells (HDPCs) and periodontal ligament fibroblasts (HPLFs).
  
  
  METHODS
  HDPCs/HPLFs obtained from 4 patients were cultured with or without various concentrations of simvastatin (0.1, 1, and 10μM) for 24, 48, and 72h. The 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to evaluate cell viability. The levels of apoptosis of HDPCs and HPLFs were measured by flow cytometry after Annexin V/propidium iodide double staining. Phalloidin-FITC and 4',6-diamidino-2-phenylindole dihydrochloride (DAPI) staining was used to examine differences in the actin cytoskeleton and nuclear morphology, respectively.
  
  
  RESULTS
  The viability of HDPCs and HPLFs was significantly reduced after simvastatin treatment in a dose- and time-dependent manner (p<0.05). The apoptosis of HDPCs and HPLFs was significantly increased in 10μM simvastatin-treated cells (p<0.05). The effect on apoptosis was comparable for HDPCs and HPLFs. Nuclear staining showed typical apoptotic nuclear condensation and fragmentation in simvastatin-treated HDPCs/HPLFs. A dose- and time-dependent simvastatin-induced disruption of the actin cytoskeleton was observed in both cell types.
  
  
  CONCLUSIONS
  Our data demonstrated that simvastatin decreases the viability of HDPCs and HPLFs, probably by inducing apoptosis.
authors.affiliation: Department of Conservative Dentistry, Faculty of Dentistry, Prince of Songkla University PSU, 15 Karnjanavanit Road, Haad Yai, Songkhla 90112, Thailand.
authors.forename: Sirinart
authors.initials: S
authors.lastname: Saewong
authors.forename: Kewalin
authors.initials: K
authors.lastname: Thammasitboon
authors.forename: Nutthamon
authors.initials: N
authors.lastname: Wattanaroonwong
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects*; D000293:Adolescent; D000328:Adult; D017209:Apoptosis / Q000187:drug effects*; D018929:Cell Culture Techniques; D002467:Cell Nucleus / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004396:Coloring Agents; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects*; D005434:Flow Cytometry / Q000379:methods; D005456:Fluorescent Dyes; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D007211:Indoles; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects*; D010590:Phalloidine / Q000031:analogs & derivatives; D019821:Simvastatin / Q000494:pharmacology*; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D055815:Young Adult
chemical_list: D004396:Coloring Agents; D005456:Fluorescent Dyes; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007211:Indoles; D013778:Tetrazolium Salts; D013844:Thiazoles; C037191:fluorescein isothiocyanate-phalloidin; D010590:Phalloidine; C007293:DAPI; D019821:Simvastatin; C022616:thiazolyl blue