Calcyclin, a Ca2+ ion-binding protein, contributes to the anabolic effects of simvastatin on bone.

Lim SK.

Departments of Internal Medicine and Anatomy, College of Medicine, Yonsei University, Seoul 120-752, Korea.

In vitro treatment with a pharmacological dose of simvastatin, a potent pro-drug of a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, stimulates bone formation. In our study, simvastatin stimulated differentiation of osteoblasts remarkably in a dose-dependent manner, with minimal effect on proliferation. To identify the mediators of the anabolic effects of simvastatin on osteoblasts, we tried to identify and characterize simvastatin-induced proteins by using proteomic analysis. Calcyclin was significantly up-regulated by more than 10 times, and annexin I was also up-regulated by simvastatin. However, annexin III, vimentin, and tropomyosin were down-regulated. Up-regulated calcyclin mRNA by simvastatin was validated by reverse transcription in mouse calvarial cells. In confocal microscope analysis, green fluorescence protein-calcyclin fusion protein was ubiquitously observed in the of MC3T3-E1 cells transfected with green fluorescence protein-calcyclin cDNA containing plasmid and was quickly concentrated in the nucleus 20 min after simvastatin treatment. Overexpression of calcyclin cDNA stimulated both the proliferation and expression of alkaline phosphatase mRNA significantly, without exposure to simvastatin in MC3T3-E1 cells. However, both the rate of proliferation of the osteoblasts and the expression of alkaline phosphatase mRNA were suppressed significantly 1 day after treatment with the calcyclin-specific small interference RNA, and furthermore, simvastatin did not overcome this suppression in the small interference RNA-pretreated MC3T3-E1 cells. In conclusion, calcyclin is one of the candidate proteins that plays a role in osteoblastogenesis in response to simvastatin, although the precise functions of calcyclin in osteoblast remain to be verified.

Online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14973129&dopt=Abstract simvastatin, Zocor




A novel anti-inflammatory role of simvastatin in a murine model of allergic asthma.

Liew FY.

Division of Immunology, Infection, and Inflammation, Section of Respiratory Medicine, University of Glasgow, Glasgow, United Kingdom.

Statins, the 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors, are effective serum cholesterol-lowering agents in clinical practice, and they may also have anti-inflammatory properties. Asthma is characterized by chronic eosinophilic inflammation in the airways, which is thought to be regulated by the activity of T lymphocytes. We therefore examined the anti-inflammatory activity of simvastatin in a murine model of allergic asthma. In mice previously sensitized to OVA, simvastatin treatment, either orally or i.p., reduced the total inflammatory cell infiltrate and eosinophilia in bronchoalveolar lavage fluid in response to inhaled OVA challenge. Simvastatin therapy i.p. was also associated with a reduction in IL-4 and IL-5 levels in bronchoalveolar lavage fluid and, at higher doses, a histological reduction in inflammatory infiltrates in the lungs. OVA-induced IL-4, IL-5, IL-6, and IFN-gamma secretion was reduced in thoracic lymph node cultures from simvastatin-treated mice. Simvastatin treatment did not alter serum total IgE or OVA-specific IgG1 and IgG2a levels. These data demonstrate the therapeutic potential of statin-sensitive pathways in allergic airways disease.

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Simvastatin reduces human atrial myofibroblast proliferation independently of cholesterol lowering via inhibition of RhoA.

Ball SG.

Institute for Cardiovascular Research, Worsley Building, University of Leeds, Leeds LS2 9JT, UK. medkep leeds.ac.uk

OBJECTIVE: Adverse atrial and ventricular myocardial remodeling is characterized by fibrosis, myocyte death or hypertrophy and fibroblast proliferation. HMG-CoA reductase inhibitors (statins) are widely prescribed cholesterol-lowering drugs that also appear to have beneficial effects on myocardial remodeling. Although statins are known to reduce myocyte hypertrophy, their effect on cardiac fibroblast proliferation is unknown. The purpose of this study was to investigate the effects of simvastatin on human atrial myofibroblast proliferation. METHODS: Cardiac myofibroblasts were cultured from biopsies of human right atrial appendage. Proliferation was quantified by cell counting and cell cycle progression determined by immunoblotting for Cyclin A. The expression, activation and intracellular localization of RhoA were investigated using immunoblotting and immunocytochemistry. RESULTS: Simvastatin (0.1-1.0 micromol/l) inhibited serum-induced myofibroblast proliferation in a concentration-dependent manner at a point upstream of Cyclin A expression. These effects were reversed by mevalonate or geranylgeranyl pyrophosphate (GGPP), but not squalene or farnesyl pyrophosphate (FPP), indicating a mechanism involving inhibition of Rho-family GTPases and independent of cholesterol synthesis. The effects of simvastatin were mimicked by inhibiting Rho geranylgeranylation or Rho-kinase activation. Furthermore, we demonstrated that simvastatin inhibited RhoA function by preventing its association with the plasma membrane and hence, its interaction with downstream effectors required for cell proliferation. CONCLUSIONS: Simvastatin reduced proliferation of cultured human atrial myofibroblasts independently of cholesterol synthesis via a mechanism involving inhibition of RhoA geranylgeranylation. Statins may therefore have an important role in preventing adverse myocardial remodeling associated with cardiac myofibroblast proliferation.

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Inhibition of in-vitro simvastatin metabolism in rat liver microsomes by bergamottin, a component of grapefruit juice.

Ubeaud G.

UMR CNRS 7034, Faculte de Pharmacie, Universite Louis Pasteur, Strasbourg, France.

Grapefruit juice can modify the pharmacokinetic parameters of many drugs, in particular simvastatin, an orally active cholesterol-lowering agent. The exact components in grapefruit juice responsible for drug interactions are not perfectly known. However, it seems that bergamottin, a furocoumarin derivative, is one of the main active components within grapefruit juice. The objective of this paper was to quantify and to characterize in-vitro the inhibitory effect of bergamottin on simvastatin metabolism by using rat and human liver microsomes. In rat liver microsomes, the incubation conditions (+/-NADPH) of bergamottin were found to influence its inhibiting capacity. In co-incubation with simvastatin, the Ki value (the equilibrium dissociation constant for the enzyme-inhibitor complex) was higher (Ki = 174 +/- 36 microM) than in pre-incubation (Ki = 45 +/- 6 microM and 4 +/- 2 microM, without and with NADPH, respectively). It thus seems that the pre-incubation of bergamottin (in particular with NADPH) increases its inhibiting capacity on simvastatin metabolism. Bergamottin metabolism study in rat liver microsomes showed the formation of two metabolites that were CYP-450 dependent. In contrast, in human liver microsomes, the incubation conditions of bergamottin did not influence its inhibiting capacity of simvastatin metabolism (Ki = 34 +/- 5 microM, Ki = 22 +/- 5 microM, Ki = 27 +/- 11 microM in coincubation and pre-incubation without and with NADPH, respectively). In rat and man, bergamottin was found to be a mixed-type inhibitor of simvastatin hepatic metabolism. However, in rat, bergamottin was partially a mechanism-based inhibitor by involvement of either bergamottin alone or one of its metabolites. The results highlight the importance of validating in-vitro models to help verify the suitability of the in-vitro model for predicting the nature and degree of metabolic drug interactions.

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Simvastatin prevents load-induced protein tyrosine nitration in overloaded hearts.

Franchini KG.

Department of Internal Medicine, School of Medicine, State University of Campinas, Brazil.

Hydroxymethylglutaryl-coenzyme A reductase inhibitors prevent load-induced left ventricular hypertrophy (LVH). Whether this effect is related to antioxidant properties of this class of drugs is poorly understood. The aim of the present report was to evaluate the regulation of nitrotyrosine production during the development of load-induced LVH and the effect of simvastatin treatment in this process. Rats were subjected to aortic constriction up to 15 days. LVH was evaluated by left/right ventricle mass ratio. Myocardial content of nitrotyrosine, nitric oxide synthase (NOS) isoforms, and phagocyte-type NAD(P)H-oxidase subunits (p67-phox and p22-phox) were analyzed by immunoblotting and immunohistochemistry assays. Another group of rats received treatment with either simvastatin or placebo for 15 days after the onset of pressure overload, and their hearts were also studied. Myocardial nitrotyrosine content was increased from 3 to 15 days of pressure overload in regions of cardiac myocytes in close apposition to myocardial stroma during LVH. Neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS) isoforms had their expression increased in coronary vessels (nNOS and iNOS) and in myocardial stroma (eNOS) from day 3 to day 7 of aortic constriction. However, p67-phox and p22-phox expression was increased in cells of myocardial stroma in parallel to augmented myocardial nitrotyrosine content. Simvastatin treatment inhibited the increases in myocardial nitrotyrosine content and in p67-phox and p22-phox expression, and significantly reduced LVH. In conclusion, antioxidant properties of simvastatin might play a role in myocardial remodeling induced by pressure overload.

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Simvastatin induces apoptosis of Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines and delays development of EBV lymphomas.

Cohen JI.

Medical Virology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

Simvastatin and pravastatin are inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase, and are used as antihypercholesterolemia drugs. Simvastatin, but not pravastatin, binds to the inserted domain of leukocyte function antigen (LFA)-1 and inhibits the function of LFA-1, including adhesion and costimulation of lymphocytes. Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) express high levels of LFA-1 on their surface and grow in tight clumps. Here we show that simvastatin (2 microM) inhibits clump formation and induces apoptosis of EBV-transformed LCLs. The apoptosis-inducing effect of simvastatin depends on binding to the inserted domain of LFA-1. Simvastatin, but not pravastatin, dissociates EBV latent membrane protein 1 from lipid rafts of LCLs, resulting in down-regulation of nuclear factor kappaB activity and induction of apoptosis. Analysis of multiple EBV-positive and -negative cell lines indicated that both LFA-1 and EBV latent membrane protein 1 expression were required for simvastatin's effects. Administration of simvastatin to severe combined immunodeficiency mice followed by inoculation with LCLs resulted in delayed development of EBV lymphomas and prolonged survival of animals. To our knowledge, this is the first report in which a drug that targets LFA-1 has been used to treat B cell lymphoma. These data suggest that simvastatin may have promise for treatment or prevention of EBV-associated lymphomas that occur in immunocompromised persons.

Online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15041742&dopt=Abstract simvastatin, Zocor