Fluvastatin induces apoptosis in rat neonatal cardiac myocytes: a possible mechanism of statin-attenuated cardiac hypertrophy

Paradoxical effects of statins on endothelial and cancer cells: the impact of concentrations

In addition to their lipid-lowering functions, statins elicit additional pleiotropic effects on apoptosis, angiogenesis, inflammation, senescence, and oxidative stress. Many of these effects have been reported in cancerous and noncancerous cells like endothelial cells (ECs), endothelial progenitor cells (EPCs) and human umbilical vein cells (HUVCs). Not surprisingly, statins' effects appear to vary largely depending on the cell context, especially as pertains to modulation of cell cycle, senescence, and apoptotic processes. Perhaps the most critical reason for this discordance is the bias in selecting the applied doses in various cells. While lower (nanomolar) concentrations of statins impose anti-senescence, and antiapoptotic effects, higher concentrations (micromolar) appear to precipitate opposite effects. Indeed, most studies performed in cancer cells utilized high concentrations, where statin-induced cytotoxic and cytostatic effects were noted. Some studies report that even at low concentrations, statins induce senescence or cytostatic impacts but not cytotoxic effects. However, the literature appears to be relatively consistent that in cancer cells, statins, in both low or higher concentrations, induce apoptosis or cell cycle arrest, anti-proliferative effects, and cause senescence. However, statins' effects on ECs depend on the concentrations; at micromolar concentrations statins cause cell senescence and apoptosis, while at nonomolar concentrations statins act reversely.

Key Enzymes for the Mevalonate Pathway in the Cardiovascular System

ABSTRACT

Isoprenylation is an important post-transcriptional modification of small GTPases required for their activation and function. Isoprenoids, including farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate, are indispensable for isoprenylation by serving as donors of a prenyl moiety to small G proteins. In the human body, isoprenoids are mainly generated by the mevalonate pathway (also known as the cholesterol-synthesis pathway). The hydroxymethylglutaryl coenzyme A reductase catalyzes the first rate-limiting steps of the mevalonate pathway, and its inhibitor (statins) are widely used as lipid-lowering agents. In addition, the FPP synthase is also of critical importance for the regulation of the isoprenoids production, for which the inhibitor is mainly used in the treatment of osteoporosis. Synthetic FPP can be further used to generate geranylgeranyl pyrophosphate and cholesterol. Recent studies suggest a role for isoprenoids in the genesis and development of cardiovascular disorders, such as pathological cardiac hypertrophy, fibrosis, endothelial dysfunction, and fibrotic responses of smooth-muscle cells. Furthermore, statins and FPP synthase inhibitors have also been applied for the management of heart failure and other cardiovascular diseases rather than their clinical use for hyperlipidemia or bone diseases. In this review, we focus on the function of several critical enzymes, including hydroxymethylglutaryl coenzyme A reductase, FPP synthase, farnesyltransferase, and geranylgeranyltransferase in the mevalonate pathway which are involved in regulating the generation of isoprenoids and isoprenylation of small GTPases, and their pathophysiological role in the cardiovascular system. Moreover, we summarize recent research into applications of statins and the FPP synthase inhibitors to treat cardiovascular diseases, rather than for their traditional indications respectively.

The effects of statins with a high hepatoselectivity rank on the extra-hepatic tissues; New functions for statins

Statins, as the most common treatment for hyperlipidemia, exert effects beyond their lipid-lowering role which are known as pleiotropic effects. These effects are mainly due to the inhibition of isoprenoids synthesis and consequently blocking prenylation of proteins involved in the cellular signaling pathways regulating cell development, growth, and apoptosis. Statins target cholesterol synthesis in the liver as the major source of cholesterol in the body and so reduce whole-body cholesterol. The reduced level of cholesterol forces other organs to an adaptive homeostatic reaction to increase their cholesterol synthesis capacity, however, this only occurs when statins have unremarkable access to the extra-hepatic tissues. In order to reduce the adverse effects of statin on the skeletal muscle, most recent efforts have been towards formulating new statins with the highest level of hepatoselectivity rank and the least level of access to the extra-hepatic tissues; however, the inaccessibility of statins for the extra-hepatic tissues may induce several biological reactions. In this review, we aim to evaluate the effects of statins on the extra-hepatic tissues when statins have unremarkable access to these tissues.

Prediction of putative small molecules for manipulation of enriched signalling pathways in hESC-derived early cardiovascular progenitors by bioinformatics analysis

Human pluripotent stem cell-derived cardiovascular progenitor cells (CPCs) are considered as powerful tools for cardiac regenerative medicine and developmental study. Mesoderm posterior1⁺ (MESP1⁺ ) cells are identified as the earliest CPCs from which almost all cardiac cell types are generated. Molecular insights to the transcriptional regulatory factors of early CPCs are required to control cell fate decisions. Herein, the microarray data set of human embryonic stem cells (hESCs)-derived MESP1⁺ cells was analysed and differentially expressed genes (DEGs) were identified in comparison to undifferentiated hESCs and MESP1-negative cells. Then, gene ontology and pathway enrichment analysis of DEGs were carried out with the subsequent prediction of putative regulatory small molecules for modulation of CPC fate. Some key signalling cascades of cardiogenesis including Hippo, Wnt, transforming growth factor-β, and PI3K/Akt were highlighted in MESP1⁺ cells. The transcriptional regulatory network of MESP1⁺ cells were visualised through interaction networks of DEGs. Additionally, 35 promising chemicals were predicted based on correlations with gene expression signature of MESP1⁺ cells for effective in vitro CPC manipulation. Studying the transcriptional profile of MESP1⁺ cells resulted into the identification of important signalling pathways and chemicals which could be introduced as powerful tools to manage proliferation and differentiation of hESC-derived CPCs more efficiently.

Cardioprotective cytokine interleukin-33 is up-regulated by statins in human cardiac tissue

Interleukin (IL)‐33 is a member of the IL‐1 family and is able to act cardioprotective. The aim of this study was to investigate the regulation of IL‐33 by 3‐hydroxy‐3‐methylglutaryl‐coenzyme‐A (HMG‐CoA) reductase inhibitors (statins) and bisphosphonates (BPs) in human cardiac tissue. The lipophilic fluvastatin, simvastatin, atorvastatin, and lovastatin as well as the nitrogenous BPs alendronate and ibandronate, but not hydrophilic pravastatin increased IL‐33 mRNA and intracellular IL‐33 protein levels in both human adult cardiac myocytes (HACM) and fibroblasts (HACF). Additionally, fluvastatin reduced soluble ST2 secretion from HACM. IL‐33 was also up‐regulated by the general inhibitor of prenylation perillic acid, a RhoA kinase inhibitor Y‐27632, and by latrunculin B, but statin‐induced IL‐33 expression was inhibited by mevalonate, geranylgeranyl pyrophosphate (GGPP) and RhoA activator U‐46619. The IL‐33 promoter was 2.3‐fold more accessible in statin‐treated HACM compared to untreated cells (P = 0.037). In explanted hearts of statin‐treated patients IL‐33 protein was up‐regulated as compared with the hearts of non‐statin‐treated patients (P = 0.048). As IL‐33 was previously shown to exert cardioprotective effects, one could speculate that such up‐regulation of IL‐33 expression in human cardiac cells, which might happen mainly through protein geranylgeranylation, could be a novel mechanism contributing to known cardioprotective effects of statins and BPs.

Atorvastatin Inhibits the HIF1α-PPAR Axis, Which Is Essential for Maintaining the Function of Human Induced Pluripotent Stem Cells

We herein report a novel mechanism of action of statin preparations using a new drug discovery method. Milk fat globule-EGF factor 8 protein (MFG-E8) was identified from the secretory component of mouse embryonic fibroblast (MEF) as a cell adhesion-promoting factor effective for screening active cellular agents of human induced pluripotent stem cells (hiPSCs) in vitro using electrochemical impedance. Our analyses showed that atorvastatin did not cause death in myocardial cells differentiated from hiPSCs but reduced the pluripotent cell survival in vitro when using serum- and albumin-free media, and inhibited the ability to form teratomas in mice. This result could have been already the cytopathic effect of atorvastatin, and complete elimination of hiPSCs was confirmed in the xenotransplantation assay. The administration of atorvastatin to hiPSCs caused the expression of hypoxia inducible factor (HIF)1α mRNA to be unchanged at 6 hr and downregulated at 24 hr. In addition, the inhibition of the survival of hiPSCs was confirmed by HIF1α-peroxisome proliferator-activated receptor (PPAR) axis inhibition. These results suggest that the addition of atorvastatin to hiPSC cultures reduces the survival of pluripotent cells by suppressing the HIF1α-PPAR axis. In summary, the HIF1α-PPAR axis has an important role in maintaining the survival of pluripotent hiPSCs.

The balance between induction and inhibition of mevalonate pathway regulates cancer suppression by statins: A review of molecular mechanisms

Statins are widely used drugs for their role in decreasing cholesterol in hypercholesterolemic patients. Statins through inhibition of Hydroxy Methyl Glutaryl-CoA Reductase (HMGCR), the main enzyme of the cholesterol biosynthesis pathway, inhibit mevalonate pathway that provides isoprenoids for prenylation of different proteins such as Ras superfamily which has an essential role in cancer developing. Inhibition of the mevalonate/isoprenoid pathway is the cause of the cholesterol independent effects of statins or pleotropic effects. Depending on their penetrance into the extra-hepatic cells, statins have different effects on mevalonate/isoprenoid pathway. Lipophilic statins diffuse into all cells and hydrophilic ones use a variety of membrane transporters to gain access to cells other than hepatocytes. It has been suggested that the lower accessibility of statins for extra-hepatic tissues may result in the compensatory induction of mevalonate/isoprenoid pathway and so cancer developing. However, most of the population-based studies have demonstrated that statins have no effect on cancer developing, even decrease the risk of different types of cancer. In this review we focus on the cancer developing "potentials" and the anti-cancer "activities" of statins regarding the effects of statins on mevalonate/isoprenoid pathway in the liver and extra-hepatic tissues.

Differential roles of the mevalonate pathway in the development and survival of mouse Purkinje cells in culture

The cerebellum is an important locus for motor learning and higher cognitive functions, and Purkinje cells constitute a key component of its circuit. Biochemically, significant turnover of cholesterol occurs in Purkinje cells, causing the activation of the mevalonate pathway. The mevalonate pathway has important roles in cell survival and development. In this study, we investigated the outcomes of mevalonate inhibition in immature and mature mouse cerebellar Purkinje cells in culture. Specifically, we found that the inhibition of the mevalonate pathway by mevastatin resulted in cell death, and geranylgeranylpyrophosphate (GGPP) supplementation significantly enhanced neuronal survival. The surviving immature Purkinje cells, however, exhibited dendritic developmental deficits. The morphology of mature cells was not affected. The inhibition of squalene synthase by zaragozic acid caused impaired dendritic development, similar to that seen in the GGPP-rescued Purkinje cells. Our results indicate GGPP is required for cell survival and squalene synthase for the cell development of Purkinje cells. Abnormalities in Purkinje cells are linked to motor-behavioral learning disorders such as cerebellar ataxia. Thus, serious caution should be taken when using drugs that inhibit geranylgeranylation or the squalene-cholesterol branch of the pathway in the developing stage.

Involvement of peptidyl-prolyl isomerase Pin1 in the inhibitory effect of fluvastatin on endothelin-1-induced cardiomyocyte hypertrophy

AIMS

Cardiac hypertrophy is elicited by endothelin (ET)-1 as well as other neurohumoral factors, hemodynamic overload, and oxidative stress; HMG-CoA reductase inhibitors (statins) were shown to inhibit cardiac hypertrophy partly via the anti-oxidative stress. One of their common intracellular pathways is the phosphorylation cascade of MEK signaling. Pin1 specifically isomerizes the phosphorylated protein with Ser/Thr-Pro bonds and regulates their activity through conformational changes. There is no report whether the Pin1 activation contributes to ET-1-induced cardiomyocyte hypertrophy and whether the Pin1 inactivation contributes to the inhibitory effect of statins. The aim of this study was to reveal these questions.

MAIN METHODS

We assessed neonatal rat cardiomyocyte hypertrophy using ET-1 and fluvastatin by the cell surface area, ANP mRNA expression, JNK and c-Jun phosphorylation, and [(3)H]-leucine incorporation.

KEY FINDINGS

Fluvastatin inhibited ET-1-induced increase in the cell surface area, ANP expression, and [(3)H]-leucine incorporation; and it suppressed the signaling cascade from JNK to c-Jun. The phosphorylated Pin1 level, an inactive form, was decreased by ET-1; however, it reached basal level by fluvastatin. Furthermore, Pin1 overexpression clearly elicited cardiomyocyte hypertrophy, which was inhibited by fluvastatin.

SIGNIFICANCE

This is the first report that ET-1-induced cardiomyocyte hypertrophy is mediated through the Pin1 activation and that the inhibitory effect of fluvastatin on cardiomyocyte hypertrophy would partly be attributed to the suppression of the Pin1 function. This study firstly suggests that Pin1 determines the size of hypertrophied cardiomyocyte by regulating the activity of phosphorylated molecules and that statins exert their pleiotropic effects partly via Pin1 inactivation.

Protective effect of Urtica dioica on liver damage induced by biliary obstruction in rats

The aim of this study was to evaluate the possible protective effects of Urtica dioica (UD) against liver damage in the common bile duct-ligated rats. A total of 24 male Sprague Dawley rats were divided into three groups, namely, control, bile duct ligation (BDL) and BDL + received UD groups, containing eight animals in each group. The rats in UD-treated groups were given UD oils (2 ml/kg) once a day intraperitoneally for 2 weeks starting 3 days prior to BDL operation. The change demonstrating the bile duct proliferation and fibrosis in expanded portal tracts includes the extension of proliferated bile ducts into the lobules; inflammatory cell infiltration into the widened portal areas were observed in BDL group. Treatment of BDL with UD attenuated alterations in liver histology. The α-smooth muscle actin, cytokeratin-positive ductular proliferation and the activity of terminal deoxynucleotidyl transferase dUTP nick end labeling in the BDL were observed to be reduced with the UD treatment. The data indicate that UD attenuates BDL-induced cholestatic liver injury, bile duct proliferation and fibrosis.

Simvastatin disrupts cytoskeleton and decreases cardiac fibroblast adhesion, migration and viability

Statins reduce the isoprenoids farnesyl and geranylgeranyl pyrophosphate, essential intermediates, which control a diversity of cellular events such as cytoskeleton integrity, adhesion, migration and viability. Cardiac fibroblasts are the major non-myocyte cell constituent in the normal heart, and play a key role in the maintenance of extracellular matrix. The effects of simvastatin on cardiac fibroblast processes previously mentioned remain unknown. Our aims were to investigate the effects of simvastatin on cytoskeleton structure and focal adhesion complex assembly and their relationships with cell adhesion, migration and viability in cultured cardiac fibroblasts. To this end, cells were treated with simvastatin for 24 h and changes in actin cytoskeleton, levels of vimentin and paxillin as well as their subcellular localization were analyzed by Western blot and immunocytochemistry, respectively. Cell adhesion to plastic or collagen coated dishes, migration in Transwell chambers, and cell viability were analyzed after simvastatin treatment. Our results show that simvastatin disrupts actin cytoskeleton and focal adhesion complex evaluated by phalloidin stain and immunocytochemistry for paxillin and vinculin. All these effects occurred by a cholesterol synthesis-independent mechanism. Simvastatin decreased cell adhesion, migration and viability in a concentration-dependent manner. Finally, simvastatin decreased angiotensin II-induced phospho-paxillin levels and cell adhesion. We concluded that simvastatin disrupts cytoskeleton integrity and focal adhesion complex assembly in cultured cardiac fibroblasts by a cholesterol-independent mechanism and consequently decreases cell migration, adhesion and viability.

The efficiency of CAPE on retardation of hepatic fibrosis in biliary obstructed rats

The aim of this study was to evaluate the possible protective effects of caffeic acid phenethyl ester (CAPE) against cholestatic oxidative stress and liver damage in the common bile duct ligated rats. A total of 18 male Sprague-Dawley rats were divided into three groups: control, bile duct ligation (BDL) and BDL + received CAPE; each group contain 6 animals. The rats in CAPE treated groups were given CAPE (10 μmol/kg) once a day intraperitoneally (i.p) for 2 weeks starting just after BDL operation. The changes demonstrating the bile duct proliferation and fibrosis in expanded portal tracts include the extension of proliferated bile ducts into lobules, inflammatory cell infiltration into the widened portal areas were observed in BDL group. Treatment of BDL with CAPE attenuated alterations in liver histology. The proliferating cell nuclear antigen and the activity of TUNEL in the BDL were observed to be reduced with the QE treatment. The application of BDL clearly increased the tissue hydroxyproline (HP) content, malondialdehyde (MDA) levels and decreased the antioxidant enzyme (superoxide dismutase (SOD), glutathione peroxidase (GPx)) activities. CAPE treatment significantly decreased the elevated tissue HP content, and MDA levels and raised the reduced of SOD, and GPx enzymes in the tissues. The data indicate that CAPE attenuates BDL-induced cholestatic liver injury, bile duct proliferation, and fibrosis. The hepatoprotective effect of CAPE is associated with antioxidative potential.

Statins and myocardial remodelling: cell and molecular pathways

The advent of statins has revolutionised the treatment of patients with raised plasma cholesterol and increased cardiovascular risk. However, the beneficial effects of this class of drugs are far greater than would be expected from lowering of cholesterol alone, and they appear to offer cardiovascular protection at multiple levels, primarily as a result of their pleiotropic activity. Indeed, their favourable effects on the heart seem to be mediated in part through reduced prenylation and subsequent inhibition of small GTPases, particularly those of the Rho family. Such statin-mediated effects are manifested by reduced onset of heart failure and improvements in cardiac dysfunction and remodelling in heart failure patients. Experimental studies have shown that statins mediate their effects on the two major resident cell types of the heart--cardiomyocytes and cardiac fibroblasts--and thus facilitate improvement of adverse remodelling of ischaemic or non-ischaemic aetiology. This review examines evidence for the cellular effects of statins in the heart, and discusses the underlying molecular mechanisms at the level of the cardiomyocyte (hypertrophy, cell death and contractile function) and the cardiac fibroblast (differentiation, proliferation, migration and extracellular matrix synthesis). The prospects for future therapies and ongoing clinical trials are also summarised.

Simvastatin induces apoptosis by a Rho-dependent mechanism in cultured cardiac fibroblasts and myofibroblasts

Several clinical trials have shown the beneficial effects of statins in the prevention of coronary heart disease. Additionally, statins promote apoptosis in vascular smooth muscle cells, in renal tubular epithelial cells and also in a variety of cell lines; yet, the effects of statins on cardiac fibroblast and myofibroblast, primarily responsible for cardiac tissue healing are almost unknown. Here, we investigated the effects of simvastatin on cardiac fibroblast and myofibroblast viability and studied the molecular cell death mechanism triggered by simvastatin in both cell types.

METHODS

Rat neonatal cardiac fibroblasts and myofibroblasts were treated with simvastatin (0.1-10μM) up to 72h. Cell viability and apoptosis were evaluated by trypan blue exclusion method and by flow cytometry, respectively. Caspase-3 activation and Rho protein levels and activity were also determined by Western blot and pull-down assay, respectively.

RESULTS

Simvastatin induces caspase-dependent apoptosis of cardiac fibroblasts and myofibroblasts in a concentration- and time-dependent manner, with greater effects on fibroblasts than myofibroblasts. These effects were prevented by mevalonate, farnesylpyrophosphate and geranylgeranylpyrophosphate, but not squalene. These last results suggest that apoptosis was dependent on small GTPases of the Rho family rather than Ras.

CONCLUSION

Simvastatin triggered apoptosis of cardiac fibroblasts and myofibroblasts by a mechanism independent of cholesterol synthesis, but dependent of isoprenilation of Rho protein. Additionally, cardiac fibroblasts were more susceptible to simvastatin-induced apoptosis than cardiac myofibroblasts. Thus simvastatin could avoid adverse cardiac remodeling leading to a less fibrotic repair of the damaged tissues.

Simvastatin has beneficial effect on pulmonary artery hypertension by inhibiting NF-κB expression

Whether Simvastatin has beneficial effect on pulmonary artery hypertension (PAH) remains unclear. This study aimed to explore the effect of simvastatin on PAH and the underlying mechanism. Male SD rats were randomized into three groups: control group, PAH model group, and treatment group with the intervention of the Simvastatin (n = 10, each group). Rat PVSMCs were isolated from pulmonary artery, cultured in vitro, and subjected to different treatment with PDGF, and/or Simvastatin or parthenolide. The mean pulmonary arterial pressure (mPAP), endomembrane proliferation in the pneumono-arteriole, and scores of the average angiemphraxis (VOS) were measured. The expression of NF-κB at mRNA and protein levels in the artery and PVSMCs was evaluated by fluorescent quantitative PCR, immunohistochemistry, and Western blot. Our results showed that mPAP, endomembrane proliferation in the pneumono-arteriole and VOS increased significantly in PAH model group compared with control group (P < 0.05). NF-κB expression was significantly higher in PAH model group than control group (P < 0.05), and also higher in the stimulated PVSMCs than control PVSMCs (P < 0.05). With the intervention of simvastatin, mPAP, endomembrane proliferation in the pneumono-arteriole and VOS decreased dramatically, compared with model group (P < 0.05). NF-κB expression was significantly decreased in both the artery and PVSMCs (P < 0.05). In conclusion, our study provides experimental evidence that NF-κB plays an important role in the occurrence of pulmonary artery hypertension and Simvastatin has beneficial effect on pulmonary artery hypertension by inhibiting the expression of NF-κB.

Atorvastatin prevents left ventricular remodeling in spontaneously hypertensive rats

Statins improve left ventricular (LV) remodeling in spontaneously hypertensive rats (SHRs). This study was designed to investigate the effects of atorvastatin administered in the early stage on LV remodeling in SHRs, and to explore the underlying mechanisms.Sixteen male 8-week-old SHRs were randomized to receive distilled water (SHR-DW) or atorvastatin (SHR-ATV) for 12 weeks. Age-matched male Wistar-Kyoto (WKY) rats gavaged with distilled water served as controls. LV remodeling was evaluated, myocardial CTGF expression levels were detected using Western blotting, and cardiomyocyte apoptosis was detected with the TUNEL method.Compared with WKY and SHR-DW, atorvastatin treatment significantly decreased systolic blood pressure in SHRs; atorvastatin significantly inhibited LV remodeling, as indicated by the reduced LV weight/body weight ratio (SHR-ATV: 4.0 ± 0.4 versus SHR-DW: 4.7 ± 0.4 mg/g, P < 0.05), cardiomyocyte diameter (SHR-ATV: 16.2 ± 2.8 versus SHR-DW: 19.0 ± 1.0 µm, P < 0.05), and interstitial fibrosis (SHR-ATV: 3.3 ± 2.1 versus SHR-DW: 4.5 ± 1.8%, P < 0.05). Compared with WKY, myocardial CTGF expression was significantly increased and cardiomyocyte apoptosis decreased in SHRs. Compared with the SHR-DW group, atorvastatin treatment significantly inhibited myocardial CTGF expression (SHR-ATV: 0.69 ± 0.21 versus SHR-DW: 1.12 ± 0.27, P < 0.05) and induced cardiomyocyte apoptosis in SHRs (SHR-ATV: 5.2 ± 0.6 versus SHR-DW: 1.9 ± 0.3%, P < 0.05).The results indicate that early-stage administration of atorvastatin effectively prevented LV remodeling in SHRs, and that inhibition of myocardial CTGF expression and induction of cardiomyocyte apoptosis may be the underlying mechanisms.

Efficient procurement of epithelial stem cells from human tissue specimens using a Rho-associated protein kinase inhibitor Y-27632

The efficient culture of stem cells from epithelial tissues such as skin and corneas is important for both experimental studies and clinical applications of tissue engineering. We now demonstrate that treatment of human-skin-derived keratinocytes with a Rho-associated protein kinase inhibitor Y-27632 for the initial 6 days of primary culture can increase the number of keratinocytes that possess stem cell properties to form colonies during in vitro culture of freshly isolated cells and subsequent passage (50-fold). Further, we show that Y-27632 treatment can increase the total number of prostate epithelial cells derived from human prostate specimens. Therefore, the use of Y-27632 during primary cultures offers a simple and effective way to prepare a large number of epithelial stem cells from various human epithelial tissues.

Can statins suppress the development of abdominal aortic aneurysms? A review of the current evidence

Statins possess several pleiotropic effects and have been shown in vitro and in vivo to inhibit the expression of inflammatory mediators and downregulate molecules involved in extracellular matrix (ECM) degradation. Recent observational studies in humans suggest that statins may have a role in abdominal aortic aneurysm (AAA) prevention or may even inhibit aneurysm expansion. In this review, we summarize the effects of statins on the vessel wall of aneurysmal aortas and currently available data concerning their inhibitory effects on aneurysm progression.

Update on statin-mediated anti-inflammatory activities in atherosclerosis

Anti-inflammatory activities of statins in atherosclerosis have been well documented by both basic research and clinical studies. Statins have been introduced in the 1980s as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors to block cholesterol synthesis and lower cholesterol serum levels. In the last three decades, statins have been shown to possess several anti-inflammatory and antioxidant activities resulting in the beneficial reduction of atherosclerotic processes and cardiovascular risk in both humans and animal models. Inflammatory intracellular pathways involving kinase phosphorylation and protein prenylation are modulated by statins. The same intracellular mechanisms might also cause statin-induced myotoxicity. In the present review, we will update evidence on statin-mediated regulation of inflammatory pathways in atherogenesis.

Inhibition of cardiac remodeling by pravastatin is associated with amelioration of endoplasmic reticulum stress

The aim of this study is to investigate whether pravastatin can inhibit cardiac remodeling and ameliorate endoplasmic reticulum (ER) stress caused by pressure overload or tumor necrosis factor alpha (TNFalpha). Either pravastatin (5 mg/kg/d) or vehicle alone was orally administered to male C57BL/6J mice from day 2 after a transverse aortic constriction (TAC) was performed. The ER stress signaling pathway was also studied in pressure-overloaded hearts and in cultured cardiomyocytes treated with TNFalpha. Four weeks after TAC, pravastatin treatment significantly reduced heart/body weight and lung/body weight ratios and increased left ventricular (LV) fractional shortening compared with the TAC alone. Markers of ER stress, such as increases in ER chaperone and C/EBP homologous protein (CHOP) expression and enhanced phosphorylation of anti-phospho-eukaryotic initiation factor 2alpha (eIF2alpha), were observed in the hearts of TAC mice, while pravastatin treatment significantly blunted these changes. Pravastatin-treated TAC mice also showed less cardiac apoptosis. Cardiac expression of TNFalpha was increased in TAC mice, and TNFalpha induced ER stress in cultured neonatal rat cardiomyocytes, either of which was significantly inhibited by pravastatin. These findings indicate that pravastatin inhibits cardiac remodeling in mice subjected to pressure overload, and that this action is associated with inhibition of the ER stress signaling pathway.

Rab-small GTPases are involved in fluvastatin and pravastatin-induced vacuolation in rat skeletal myofibers

Three-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitors, known as statins, induce skeletal muscle injury including myalgia, myositis, and rhabdomyolysis. The mechanism of this myotoxicity remains unknown. This study examined the effect of statins on single skeletal myofibers enzymatically isolated from the rat flexor digitorum brevis muscles. Fluvastatin and pravastatin induced the formation of numerous vacuoles in the myofibers after 72 h of treatment. This effect progressed in a time- and concentration-dependent manner and, consequently, cell death occurred after 120 h. Electron micrographs revealed craters along the sarcolemma and swelling of the sarcoplasmic reticula and mitochondria, in addition to intracellular vacuoles. When caffeine was added after 72 h of fluvastatin treatment, contractile shortening of statin-treated myofibers was significantly attenuated and blebs formed on the surface of the myofibers. The coapplication of geranylgeranylpyrophosphate (GGPP) with fluvastatin prevented the morphological changes, while that of farnesylpyrophosphate (FPP) was ineffective. Furthermore, perillyl alcohol, an inhibitor of Rab geranylgeranyl transferase and geranylgeranyl transferase-I (GGTase-I), mimicked the effect of statins, while a specific GGTase-I inhibitor (GGTI-298) or a farnesyl transferase inhibitor (FTI-277) failed to do so. These results suggest that the inactivation of Rab GTPase, which involved in intracellular membrane transport, is a crucial factor in statin-induced-morphological abnormality in skeletal muscle fibers.

Effective uptake of N-acetylglucosamine-conjugated liposomes by cardiomyocytes in vitro

A drug delivery system (DDS) that targets the injured myocardium would serve as a novel therapeutic tool for cardiac diseases. To develop such a DDS, we investigated the interaction of 2 types of glycoside-conjugated liposomes containing a fluorescence substrate with cardiomyocytes. Flow cytometry revealed that cardiomyocytes adequately interact with N-acetylglucosamine-conjugated liposomes (GlcNAc-Ls). Furthermore, to confirm whether the agents encapsulated in GlcNAc-Ls affect the intracellular environment of cardiomyocytes, we prepared GlcNAc-Ls-containing pravastatin and examined the effect of pravastatin on cardiomyocytes. Pravastatin is a 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor (statin) and is hydrophilic. It is reported that lipophilic statins enhance nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression by interleukin-1beta (IL-1beta)-stimulated cardiomyocytes. The hydrophilic nature of pravastatin prevents its entry into cardiomyocytes; therefore, it cannot enhance both these processes. Treatment with GlcNAc-Ls-containing pravastatin specifically enhanced NO production and iNOS expression by IL-1beta-stimulated cardiomyocytes. Based on these results, we found that cardiomyocytes exhibit a high degree of interaction with GlcNAc-Ls, and GlcNAc-Ls-encapsulated agents can be effectively taken up by cardiomyocytes. We suggest that GlcNAc-Ls can be utilized therapeutically as a DDS for the injured myocardium.

Preventive effects of bicarbonate on cerivastatin-induced apoptosis

Although HMG-CoA reductase inhibitors such as statins are the most widely used cholesterol-lowering agents, there is a risk of myopathy or rhabdmyolysis occurring in patients taking these drugs. It has been reported that a number of lipophilic statins cause apoptosis in various cells, but it is still not clear whether intracellular acidification is involved in statin-induced apoptosis. There have been few studies aimed at identifying compounds that suppress statin-induced myotoxicity. In the present study, we examined the relationship between cerivastatin-induced apoptosis and intracellular acidification and the effect of bicarbonate on cerivastatin-induced apoptosis using an RD cell line as a model of in vitro skeletal muscle. Cerivastatin reduced the number of viable cells and caused dramatic morphological changes and DNA fragmentation in a concentration-dependent manner. Moreover, cerivastatin-induced apoptosis was associated with intracellular acidification and caspase-9 and -3/7 activation. On the other hand, bicarbonate suppressed cerivastatin-induced pH alteration, caspase activation, morphological change and reduction of cell viability. Accordingly, bicarbonate suppressed statin-induced apoptosis. The strategy to combine statins with bicarbonate can lead to reduction in the chance of the severe adverse events including myopathy or rhabdmyolysis.

Reduction of protein synthesis and statin-induced cardiomyocyte cell death

The objective of this study was to determine whether an HMG Co A reductase inhibitor (statin) reduces protein synthesis in cardiomyocytes and whether this action maybe an underlying mechanism for statin-induced cell death. Cardiomyocytes from embryonic chick heart were maintained in culture. Cells exposed to lovastatin for 4 h showed a concentration dependent reduction in protein synthesis as assessed by [3H] leucine incorporation and [35S] methionine incorporation. Compared to control, lovastatin 100 microM, which produced a 25% increase in cell death, induced a three-fold reduction in methionine incorporation. [35S] methionine autoradiography showed little (new) protein synthesis at concentrations of lovastatin of 70 microM or higher; an effect that was not limited to specific proteins. Cardiomyocytes treated with lovastatin showed morphologic changes in the nucleoli consistent with insufficient protein synthesis. These cardiomyocytes manifested cell death under conditions of reduced protein synthesis. Interruption of protein synthesis with cycloheximide, a ribosomal RNA transcription inhibitor or reduction in protein substrate availability by lowering the media concentration of fetal calf serum was associated with a concentration-dependent reductions in cell viability. Importantly, stimulation of protein synthesis by higher concentrations of fetal calf serum limited lovastatin-induced cell death. These data suggest that statin-induced inhibition of protein synthesis is an underlying mechanism for statin-induced cell death.

Rho kinase in the regulation of cell death and survival

Rho kinase (ROCK) belongs to a family of serine/threonine kinases that are activated via interaction with Rho GTPases. ROCK is involved in a wide range of fundamental cellular functions, such as contraction, adhesion, migration, and proliferation. Recent studies have shown that ROCK plays an important role in the regulation of apoptosis in various cell types and animal disease models. Two ROCK isoforms, ROCK1 and ROCK2, are assumed to be function redundant, this based largely on kinase construct overexpression and chemical inhibitors (Y27632 and fasudil) which inhibit both ROCK1 and ROCK2. Gene targeting and RNA interference approaches allow further dissection of distinct cellular, physiological, and patho-physiological functions of the two ROCK isoforms. This review, based on recent molecular, cellular, and animal studies, focuses on the current understanding of ROCK signaling in the regulation of apoptosis and highlights new findings from recently generated ROCK-deficient mice.

Fluvastatin reduced liver injury in rat model of extrahepatic cholestasis

Inhibitors of 3-hydroxy-3methylglutarly coenzyme A, reductase, namely statins, exert pleiotropic actions beyond lipid-lowering effects. In ex vivo and in vitro studies, statins have antioxidative and antiinflammatory effects. Herein, we sought to determine whether treatment with fluvastatin (FV) would be beneficial in a rat model of common bile duct ligation (BDL)-induced liver injury. Female rats were subjected to a sham (n=10) or BDL (n=20). Obstructive jaundice was induced in rats by the ligation and division of the common bile duct. Three days after operation, rats subjected to CBDL were randomized to receive treatment with either FV (10 mg/kg) or saline every day over a 10 days experimental period. High levels of alanine aminotransferase, aspartate aminotransferase, and gamma glutamyltransferase decreased significantly (P<0.05) in animals treated with FV with compared to saline-administrated BDL animals. Compared with sham-operated rats, CBDL rats showed significantly higher levels of total nitrite and nitrate, malondihaldehyde, tumor necrosis factor alpha, myeloperoxidase, and lower concentrations of glutathione, superoxide dismutase, and catalase in the liver tissue (P<0.001). All of these changes were significantly attenuated (P<0.05) by treatment with FV after CBDL. CBDL was associated with increased apoptosis and nuclear factor kappa beta expression in saline-treated rats. Treatment with FV also decreased these parameters. These data support the view that FV ameliorates hepatic inflammation, lipid peroxidation, and tissue injury in rats subjected to CDBL. FV warrants further evaluation as an adjunctive treatment to ameliorate liver injury from extrahepatic biliary obstruction.

Statins protect human aortic smooth muscle cells from inorganic phosphate-induced calcification by restoring Gas6-Axl survival pathway

Vascular calcification is clinically important in the development of cardiovascular disease. It is reported that hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (statins) inhibited vascular calcification in several clinical trials. However, the mechanism is poorly understood. Recently, it has been suggested that apoptosis is one of the important processes regulating vascular smooth muscle cell (VSMC) calcification. In this study, we investigated the effect of statins on VSMC calcification by testing their effect on apoptosis, focusing in particular on regulation of the survival pathway mediated by growth arrest-specific gene 6 (Gas6), a member of the vitamin K-dependent protein family, and its receptor, Axl. In human aortic smooth muscle cells (HASMC), statins significantly inhibited inorganic phosphate (Pi)-induced calcification in a concentration-dependent manner (reduced by 49% at 0.1 micromol/L atorvastatin). The inhibitory effect of statins was mediated by preventing apoptosis, which was increased by Pi in a concentration-dependent manner, and not by inhibiting sodium-dependent phosphate cotransporter (NPC) activity, another mechanism regulating HASMC calcification. Furthermore, the antiapoptotic effect of statins was dependent on restoration of Gas6, whose expression was downregulated by Pi. Restoration of Gas6 mRNA by statins was mediated by mRNA stabilization, and not by an increase in transcriptional activity. Suppression of Gas6 using small interfering RNA and the Axl-extracellular domain abolished the preventive effect of statins on Pi-induced apoptosis and calcification. These data demonstrate that statins protected HASMC from Pi-induced calcification by inhibiting apoptosis via restoration of the Gas6-Axl pathway.

Differential roles of MAP kinases in atorvastatin-induced VEGF release in cardiac myocytes

Statins, specific inhibitors of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, are now widely used for treatment of patients with hypercholesterolemia. In addition to the reduction of cholesterol biosynthesis, accumulating evidence indicates that statins have several pleiotropic effects especially on cardiovascular system. However, the exact role of statin in cardiac myocytes remains unclear. In the present study, we investigated whether atorvastatin induces vascular endothelial growth factor (VEGF) release in cardiac myocytes, and the underlying mechanism. We observed that atorvastatin significantly stimulated VEGF release in a dose-dependent manner. It induced the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase but not SAPK (stress-activated protein kinase)/JNK (c-Jun N-terminal kinase). The atorvastatin-induced VEGF release was enhanced by PD98059, which is a specific inhibitor of the upstream kinase that activates p44/p42 MAP kinase (MEK). Further, it was significantly reduced by SB203580, a specific inhibitor of p38 MAP kinase. Furthermore, the atorvastatin-induced phosphorylation of p38 MAP kinase was attenuated by SB203580, whereas it was enhanced by PD98059. Taken together, these results suggest that the atorvastatin-induced VEGF release in cardiac myocytes is positively regulated by p38 MAP kinase and negatively regulated byp44/p42 MAP kinase and that the atorvastatin-induced phosphorylation of p38 MAP kinase is regulated by p44/p42 MAP kinase in these cells.

3-HMG-Coenzyme A Reductase Inhibition and Extracellular Matrix Gene Expression in the Pressure-Overloaded Rat Heart

The purpose of this study was to determine whether 3-HMG-Coenzyme A (HMG-CoA) reductase inhibition would attenuate the early pressure overload-induced activation of extracellular matrix genes in the left ventricle (LV) of the heart. Sprague-Dawley rats were randomized to 1 of 4 treatment groups: sham-operation+vehicle (SH-V), aortic constriction+vehicle (AC-V), AC+rosuvastatin (RSV, 2 mg/kg; AC-LO), and AC+RSV (10 mg/kg; AC-HI). Rats were injected with normal NaCl (V) or RSV once daily, beginning 1 day before surgery, and killed 1 or 3 days after surgery. Hemodynamic measurements were made in the open-chest anesthetized state. LV levels of transforming growth factor beta1 (TGF-beta1), procollagen 1 (C1), and fibronectin (FN) mRNA were measured by Northern blotting. AC induced a approximately 25% increase in LV weight after 3 days that was not altered by RSV treatment. LV expression of TGF-beta1, C1, and FN mRNA was approximately 2-fold, approximately 2.5-fold, and approximately 5-fold greater, respectively, in hearts of AC-V compared to SH-V rats 3 days post-operation, and was not significantly decreased by either dose of RSV. Inhibition of HMG-CoA reductase does not attenuate the pronounced aortic constriction-induced increases in the early expression of TGF-beta1, C1, and FN in this model of acute pressure overload of the rat heart.

Apoptosis of rheumatoid synovial cells by statins through the blocking of protein geranylgeranylation: a potential therapeutic approach to rheumatoid arthritis

OBJECTIVE

To determine whether statins induce apoptosis in rheumatoid arthritis (RA) synoviocytes.

METHODS

The effects of lipophilic and hydrophilic statins (fluvastatin and pravastatin, respectively) on the apoptosis of cultured RA synoviocytes were examined in vitro. Apoptosis was analyzed by flow cytometry after staining with JC-1 (to measure the mitochondrial transmembrane potential), active caspase 3, annexin V, and propidium iodide. Add-back experiments were conducted to determine which downstream products of the mevalonate pathway could suppress apoptosis. Modulation of various signaling pathways induced by statins, including protein prenylation, was also investigated.

RESULTS

Fluvastatin, but not pravastatin, induced apoptosis in RA synoviocytes in a concentration-dependent (1-10 microM) and time-dependent (48-96 hours) manner. Another lipophilic statin, pitavastatin, displayed almost the same effects as fluvastatin. In sharp contrast, lipophilic statins did not significantly increase apoptosis in synoviocytes from patients with osteoarthropathy. Apoptosis induced by fluvastatin was mitochondrial- and caspase 3-dependent and was abrogated by mevalonate and geranylgeranyl pyrophosphate, but not by farnesyl pyrophosphate. In addition, the geranylgeranyl transferase inhibitor GGTI-298 mimicked the effect of fluvastatin on RA synoviocytes. Treatment of RA synoviocytes with the RhoA kinase inhibitor Y-27632 caused apoptosis. Fluvastatin decreased the amount of RhoA protein in the membrane fraction, but increased the amount in the cytosolic fraction.

CONCLUSION

Fluvastatin induced apoptosis in RA synoviocytes through a mitochondrial- and caspase 3-dependent pathway and by the blockage of mevalonate pathways, particularly through the inhibition of protein geranylgeranylation and RhoA/RhoA kinase pathways. These findings suggest that lipophilic statins have potential as novel therapeutic agents for RA.

Hydroxymethylglutaryl-coenzyme A reductase inhibitors induce apoptosis in human cardiac myocytes in vitro

Recent findings have implicated hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors or statins, an established class of drugs for the treatment of hypercholesterolemia, in tissue remodeling in the heart. Statins induce apoptosis in different cell culture systems including rat neonatal cardiomyocytes. We investigated possible effects of different statins in vitro in human adult cardiac myocytes on the expression of proteins thought to be involved in the regulation of apoptosis such as Mcl-1, an inhibitor of apoptosis, Bax, an inducer of apoptosis, as well as on cytoplasmic histone-associated-DNA-fragments. Human adult cardiac myocytes (HACM) were treated with different statins at concentrations from 0.01 to 5 microM for up to 96 h. Whereas the lipophilic statin simvastatin at a concentration of 5 microM downregulated Mcl-1 mRNA by 49%, the hydrophilic pravastatin had no effect. Bax mRNA levels were not affected by neither of the statins. Simvastatin but not pravastatin reduced Mcl-1 protein expression whereas Bax protein was not detectable in HACM as determined by Western blotting. Simvastatin, atorvastatin and fluvastatin induced an up to seven-fold increase in histone-associated-DNA-fragments whereas pravastatin did not. Simvastatin up regulated histone-associated-DNA-fragments dose-dependently, and mevalonate and geranylgeranyl pyrophosphate reversed this effect to control levels. Our results show that lipophilic statins can induce a pro-apoptotic state in human adult cardiac myocytes in vitro. We speculate that, similar to findings in animal models, statins might be involved in the attenuation of cardiac hypertrophy and remodeling in humans by modulating the balance between cell survival and apoptosis.

The association between RhoB and caspase-2: changes with lovastatin-induced apoptosis

Because cytoskeletal actin is regulated, in part, by Rho, and because Rho and caspases are involved in apoptosis, we sought to determine whether there was an association between RhoB and caspase-2. A RhoB–caspase-2 association was consistently demonstrated in neonatal mouse cardiomyocytes with Western Blotting, either after im mun o precipitation with RhoB followed by immunoblotting with caspase-2, or in reciprocal experiments after immuno precipitation with caspase-2 and immunoblotting with RhoB (n = 14). Although the RhoB–caspase-2 complex was constitutively present, the link between RhoB and caspase-2 may be operative in apoptosis because the HMG-CoA reductase inhibitor lovastatin increased the RhoB–caspase complex, especially in the nuclear fraction of the cell, with a peak occurrence 2 h after treatment. This association was unaffected by the caspase-2 inhibitor zVDVAD. Lovastatin produced apoptosis that was accompanied by an activation of caspase-2, as demonstrated by its immunohistochemistry and by the fact that the caspase-2 inhibitor zVDVAD reduced lovastatin-induced apoptosis. Lovastatin induced dramatic changes in cell morphology and a reduction in F-actin. Immunoblotting for actin suggests that lovastatin does not induce a degradation of the actin molecule, but rather affects filamentous F-actin. Caspase-2 inhibition with zVDVAD reduced lovastatin-induced alteration in cytoskeletal F-actin. The Rho inhibitor, Clostridium difficile toxin B, blunted the ability of lovastatin to induce apoptosis. In summary, these data show a previously unrecognized association between RhoB and caspase-2 in the cytosolic and nuclear fractions, which has ramifications for processes regulated by RhoB and caspase-2, including apoptosis.Key words: actin, apoptosis, caspase-2, cardiomyocyte, heart, lovastatin.

Fluvastatin in the treatment of dyslipidemia associated with chronic kidney failure and renal transplantation

Premature atherosclerotic coronary heart disease driven by multiple risk factors is a major cause of morbidity and mortality among the 6 million patients in the United States with chronic renal failure. Consensus is that kidney failure and renal transplantation patients should be treated aggressively for dyslipidemia. Major medical literature databases were searched for published information about fluvastatin, a HMG-CoA reductase inhibitor, used in patients with impaired renal function. This article characterizes the dyslipidemia observed in these clinical settings and reviews the clinical experience with fluvastatin.

Simvastatin Attenuates Expression of Cytokine-inducible Nitric-oxide Synthase in Embryonic Cardiac Myoblasts

Cardiac stem cells or myoblasts are vulnerable to inflammatory stimulation in hearts with infarction or ischemic injury. Widely used for the prevention and treatment of atherosclerotic heart disease, the cholesterol-lowering drugs statins may exert anti-inflammatory effects. In this study, we examined the impact of inhibition of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase with simvastatin on the expression of inducible nitric-oxide synthase (iNOS) in embryonic cardiac myoblasts stimulated with the proinflammatory cytokines, interleukin-1 or tumor necrosis factor. Treatment with simvastatin significantly reduced the levels of iNOS mRNA and protein in cytokine-treated rat H9c2 cardiac embryonic myoblasts. Addition of the HMG-CoA reductase product, L-mevalonate, and the by-product of cholesterol synthesis, geranylgeranyl pyrophosphate, could reverse the statin inhibitory effect on iNOS expression. Simvastatin treatment lowered the Rho GTPase activities, whereas the Rho-associated kinase inhibitor Y27632 partially blocked the statin inhibitory effect on nitrite production in the cytokine-treated H9c2 cells. Treatment with simvastatin led to inactivation of NF-kappaB by elevation of the NF-kappaB inhibitor IkappaB and reduction of the NF-kappaB nuclear contents in the cytokine-stimulated H9c2 cells. Hence, treatment with simvastatin can attenuate iNOS expression and NO synthesis in cytokine-stimulated embryonic cardiac myoblasts. The statin inhibitory effect may occur through isoprenoid-mediated intracellular signal transduction, which involves several key signal proteins, such as Rho kinase and IkappaB/NF-kappaB. These data suggest that statin therapy may protect the cardiac myocyte progenitors against the cytotoxicity of cytokine-induced high output of NO production in infarcted or ischemic hearts with inflammation.

A review of the lipid-related effects of fluvastatin

BACKGROUND

Statin therapy has been shown to significantly decrease vascular events and overall mortality in primary and secondary prevention trials. This review considers the pharmacology, nonlipid-lowering effects and clinical trial evidence of fluvastatin based on a survey of PubMed entries.

FINDINGS

Recent clinical data show that treatment with fluvastatin is associated with a variety of benefits in different high-risk populations along with a good safety profile. Fluvastatin exerts non-lipid lowering-associated pleiotropic effects in both clinical and experimental studies. Furthermore, an extended-release formulation of fluvastatin with a favourable pharmacokinetic profile is available.

CONCLUSION

Treatment with fluvastatin offers a convenient, safe and evidence-based approach to managing dyslipidaemias and preventing vascular events.

Mevastatin induces apoptosis in HL60 cells dependently on decrease in phosphorylated ERK

Mevastatin which is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol synthesis, suppress cell proliferation and induce apoptosis. However, the molecular mechanism of apoptosis induction is not well understood. So, in the present study, we attempted to clarify the mechanism by which mevastatin induces apoptosis in HL60 cells. It was found that mevastatin induced apoptosis. At that time, we observed an increase in caspase-3 activity and morphological fragmentation of the nuclei. The apoptosis induced by mevastatin was not inhibited by the addition of farnesyl pyrophosphate (FPP), squalene, ubiquinone, and isopentenyladenine, but was inhibited by the addition of geranylgeranyl pyrophosphate (GGPP). When we examined the survival signals at the time of apoptotic induction, we also observed that the administration of mevastatin had caused a remarkable decrease in the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). However, other survival signals, such as nuclear factor kappa B (NF-kappaB), protein kinase B (Akt), and p38 mitogen-activated protein kinase (p38), exhibited no change. In addition, no quantitative change was observed in Bcl-2, which was an anti-apoptosis protein. It was also observed that apoptosis was induced when U0126, an MEK inhibitor, was added to the cells to inhibit ERK. These results suggested that mevastatin induced apoptosis when it inhibited GGPP biosynthesis and consequently decreased the level of phosphorylated ERK, which was a survival signal; moreover, at that time, there was no influence on NF-kappaB, Akt, p38, and Bcl-2. The results of this study also suggested that mevastatin could be used as an anticancer agent.

Fluvastatin: clinical and safety profile

Therapy with HMG-CoA reductase inhibitors (statins) has been shown to significantly reduce major coronary events and death in a wide range of individuals at risk for these events. In addition, recent observations suggest that some of the clinical benefits associated with statin therapy may be pleiotropic; that is, independent of their cholesterol-inhibiting action. It is clear that the clinical benefits associated with statin therapy far outweigh the risks; however, there may be important clinical differences among agents within the class, related to both benefits and drug safety. Evaluation of the benefit-to-risk profile for each available statin should include considering the results of randomised clinical outcome trials, the safety record of each agent, effect on lipoproteins and evidence of beneficial pleiotropic properties.Recently, data from several clinical outcome trials have shown that substantial benefits are associated with treatment with fluvastatin in diverse populations. In particular, data from two large, randomised clinical trials have demonstrated that fluvastatin is effective for secondary prevention of cardiac events in patients following coronary intervention procedures, and for primary prevention of cardiac events in renal transplant recipients. Pleiotropic benefits for fluvastatin have been shown in experimental and clinical studies as well. Fluvastatin was the first statin available as an extended-release product (fluvastatin XL 80mg); both formulations have demonstrated efficacy and safety in a wide range of patients. Taken together, these clinical outcomes and safety data suggest a strong benefit-to-risk profile for fluvastatin.

Statins Inhibit β-Adrenergic Receptor–Stimulated Apoptosis in Adult Rat Ventricular Myocytes via a Rac1-Dependent Mechanism

Background— 3-Hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) inhibit myocyte hypertrophy in vitro and ameliorate the progression of cardiac remodeling in vivo, possibly because of inhibition of the small GTPase Rac1. The role of Rac1 in mediating myocyte apoptosis is not known. β-Adrenergic receptor (βAR)-stimulated myocyte apoptosis is mediated via activation of c-Jun NH 2 -terminal kinase (JNK), leading to activation of the mitochondrial death pathway. We hypothesized that βAR-stimulated apoptosis in adult rat ventricular myocyte (ARVMs) is mediated by Rac1 and inhibited by statins.

Methods and Results— βAR stimulation increased apoptosis, as assessed by transferase-mediated nick-end labeling, from 5±1% to 24±2%. βAR stimulation also increased Rac1 activity. Adenoviral overexpression of a dominant-negative mutant of Rac1 inhibited βAR-stimulated apoptosis, JNK activation, cytochrome C release, and caspase-3 activation. Cerivastatin likewise inhibited the βAR-stimulated activation of Rac1, decreased βAR-stimulated apoptosis to 11±2%, and inhibited JNK activation, cytochrome C release, and caspase-3 activation.

Conclusions— βAR stimulation causes Rac1 activation, which is required for myocyte apoptosis and leads to activation of JNK and the mitochondrial death pathway. Cerivastatin inhibits βAR-stimulated activation of Rac1 and thereby inhibits JNK-dependent activation of the mitochondrial death pathway and apoptosis. The beneficial effects of statins on the myocardium may be mediated in part via inhibition of Rac1-dependent myocyte apoptosis.

Apoptotic injury in cultured human hepatocytes induced by HMG-CoA reductase inhibitors

Hepatotoxicity is the major complaint during therapy with lipid-lowering agents such as statins, although the cellular mechanisms underlying the statin-induced liver injury are not fully understood. Using cultured human hepatocytes, we investigated the effects of lipophilic as well as hydrophilic statins on the cell viability. Lipophilic statins, including simvastatin, lovastatin, cerivastatin, fluvastatin and atorvastatin, reduced the viability of hepatocytes as assessed by the mitochondrial enzyme activity to reduce WST-8, however, a hydrophilic pravastatin did not cause cell injury. The simvastatin-induced loss of cell viability was attenuated by mevalonate or geranylgeranyl pyrophosphate. Simvastatin-induced DNA fragmentation and increased the number of cells stained with annexin V and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling, both of which were reversed by caspase inhibitors such as zDEVD-fmk, zLEHD-fmk and zIETD-fmk. Consistent with these data, the activities of caspase-3, caspase-9 and caspase-8 were elevated by simvastatin. Simvastatin reduced the protein content and mRNA expression for bcl-2 without affecting bax mRNA expression. On the other hand, both lipophilic and hydrophilic statins significantly reduced the content of endogenous cholesterol. These findings suggest that lipophilic statins cause an apoptotic injury in human hepatocytes by stimulating caspase-3 subsequent to the activation of caspase-9 and caspase-8, in which the inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase may be involved.

ANTI-APOPTOTIC EFFECT OF ATORVASTATIN, A 3-HYDROXY-3-METHYLGLUTARYL COENZYME A REDUCTASE INHIBITOR, ON CARDIAC MYOCYTES THROUGH PROTEIN KINASE C ACTIVATION

Pleiotropic effects of statins, which are independent of lipid lowering, have been reported. In the present study, we examined the effect of a statin on apoptosis of adult rat cultured cardiac myocytes. We used the protein kinase C (PKC) inhibitors staurosporine (1 micro mol/L), chelerythrine (10 micro mol/L) and rottlerin (5 micro mol/L) to induce myocyte apoptosis. The effect of atorvastatin (10(-7) g/mL), a statin, on myocyte apoptosis induced by these PKC inhibitors was examined. All these PKC inhibitors markedly increased the percentage of terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL)-positive myocytes. This increase was significantly suppressed by atorvastatin treatment. Both chelerythrine and rottlerin induced subcellular translocation of PKCdelta and elevated caspase-3 activity in myocytes. The changes in the subcellular distribution of PKCdelta and caspase-3 activity induced by these PKC inhibitors were suppressed by atorvastatin treatment. The results of the present study suggest that the inhibitory effect of atorvastatin on apoptosis of adult rat cardiac myocytes induced by the PKC inhibitors is through activation of PKCdelta pathway.

Comparing myotoxic effects of squalene synthase inhibitor, T-91485, and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors in human myocytes

TAK-475 is a squalene synthase inhibitor, rapidly metabolized to T-91485 in vivo. We investigated the myotoxicities of T-91485 and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors in a human rhabdomyosarcoma cell line, RD, and in human skeletal myocytes. In differentiated RD cells, T-91485, atorvastatin (ATV) and simvastatin acid (SIM) inhibited cholesterol biosynthesis, with IC(50) values of 36, 2.8 and 3.8 nM, respectively. ATV and SIM decreased the intracellular ATP content, with IC(25) values (concentrations giving a 25% decrease in intracellular ATP content) of 0.61 and 0.44 microM, respectively. Although T-91485 potently inhibited cholesterol synthesis in RD cells, the IC(25) value exceeded 100 microM. In human skeletal myocytes, T-91485, ATV and SIM concentration-dependently inhibited cholesterol biosynthesis, with IC(50) values of 45, 8.6 and 8.4 nM, respectively. ATV and SIM decreased intracellular ATP content, with IC(25) values of 2.1 and 0.72 microM, respectively. Although T-91485 potently inhibited cholesterol synthesis, the IC(25) value exceeded 100 microM. Myotoxicity induced by ATV was prevented by mevalonate or geranylgeranyl-PP, but not by squalene in skeletal cells. Furthermore, T-91485 attenuated the myotoxicity of ATV. These findings suggest that TAK-475 and T-91485 may not only be far from myotoxic, they may also decrease statin-induced myotoxicity in lipid-lowering therapy.