title: Simvastatin inhibits cell cycle progression in glucose-stimulated proliferation of aortic vascular smooth muscle cells by up-regulating cyclin dependent kinase inhibitors and p53.
abstract: Simvastatin was reported to attenuate platelet-derived growth factor (PDGF)-induced vascular smooth muscle proliferation by up-regulation of cyclin dependent kinase (CDK) inhibitor p27, but had no effect on p16, p21, p53 expression. We investigate the mechanisms by which simvastatin inhibits vascular smooth muscle cell (VSMC) growth in high glucose conditions to mimic diabetes. Simvastatin was added to A7r5 cells cultured in high glucose (25 mM) medium, mimicking diabetes. We used an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to evaluate cell viability; flow cytometric analysis for cell counts distribution in the cell cycle; and Western blot, immunoblotting, and immunoprecipitation analyses to evaluate the effects of simvastatin on CDK activity and cell cycle regulatory proteins. Cell counts were significantly increased in G0/G1 phase and significantly decreased in S and G2/M phases. In our study, low dose of simvastatin had no significant inhibitory effect on VSMC growth in normal glucose condition. However, both low and high doses of simvastatin inhibited VSMC growth significantly in a dose-dependent manner in high glucose status. We also found that simvastatin inhibited phosphorylation of Rb, promoted expression of p53, p16, p21, p27 and decreased CDK2/4 activity. In conclusion, simvastatin inhibits VSMC proliferation in high glucose status, mimicking diabetes, inducing a G0/G1 phase cell cycle growth arrest by acting on multiple steps upstream of pRb, including inhibition of CDK2/4 expression and up-regulation of p53, p21, p16, and p27. We propose that statins may be used more extensively in diabetic patients regardless of lipid status for preventing atherosclerosis and restenosis after PCI.
authors.affiliation: Department of Internal Medicine, Institute of Medicine, Chung-Shan Medical University Hospital, No. 110, Sec. 1, Jianguo N. Road, Taichung 402, Taiwan.
authors.forename: Kuei-Chuan
authors.initials: KC
authors.lastname: Chan
authors.forename: Chau-Jong
authors.initials: CJ
authors.lastname: Wang
authors.forename: Hsieh-Hsun
authors.initials: HH
authors.lastname: Ho
authors.forename: Hsiang-Mei
authors.initials: HM
authors.lastname: Chen
authors.forename: Chien-Ning
authors.initials: CN
authors.lastname: Huang
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects; D052160:Benzothiazoles / Q000494:pharmacology; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D050756:Cyclin-Dependent Kinase Inhibitor Proteins / Q000096:biosynthesis* / Q000235:genetics; D005434:Flow Cytometry; D005947:Glucose / Q000494:pharmacology*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D047468:Immunoprecipitation; D032389:Myocytes, Smooth Muscle / Q000187:drug effects*; D051381:Rats; D019821:Simvastatin / Q000494:pharmacology*; D013778:Tetrazolium Salts; D013844:Thiazoles; D014050:Toluene / Q000031:analogs & derivatives / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D052160:Benzothiazoles; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D013778:Tetrazolium Salts; D013844:Thiazoles; D016159:Tumor Suppressor Protein p53; D014050:Toluene; D019821:Simvastatin; C121565:pifithrin; C022616:thiazolyl blue; D005947:Glucose