Statins: Mechanism of Action and Effects

J.Cell.Mol.Med. Vol 5, No 4, 2001 pp. 378-387 Review

Statins: mechanism of action and effects

Camelia Stancu, Anca Sima *

"Nicolae Simionescu" Institute of Cellular Biology and Pathology, Bucharest, Romania

Received: November 12, 2001; Accepted: December 5, 2001

• Introduction • Effects on • Classification of statins - cholesterol esterification and - How they are obtained its accumulation in macrophages - Liver metabolism - endothelial cell function - Physico-chemical properties - inflammatory process - Specific activity - proliferation, migration and • Mechanisms for the action of statins apoptosis of arterial smooth muscle cells - Mechanisms involving lipids - stability of the atherosclerotic plaque - Mechanisms involving intracellular - platelets activation signaling pathways - coagulation process • Beneficial effects of statins • Adverse effects of statins therapy • Conclusions Abstract

The beneficial effects of statins are the result of their capacity to reduce cholesterol biosyntesis, mainly in the liver, where they are selectively distributed, as well as to the modulation of lipid metabolism, derived from their effect of inhibition upon HMG-CoA reductase. Statins have antiatherosclerotic effects, that positively correlate with the percent decrease in LDL cholesterol. In addition, they can exert antiatherosclerotic effects independently of their hypolipidemic action. Because the mevalonate metabolism generates a series of isoprenoids vital for different cellular functions, from cholesterol synthesis to the control of cell growth and differentiation, HMG-CoA reductase inhibition has beneficial pleiotropic effects. Consequently, statins reduce significantly the incidence of coronary events, both in primary and secondary prevention, being the most efficient hypolipidemic compounds that have reduced the rate of mortality in coronary patients. Independent of their hypolipidemic properties, statins interfere with events involved in bone formation and impede tumor cell growth.

Keywords: HMG CoA reductase • cell signaling • LDL oxidation • atherosclerosis • cancer • osteoporosis • endothelial dysfunction • macrophage • smooth muscle cell

*Correspondence to: Dr. Anca SIMA 8, B. P. Hasdeu Street, Bucharest 79691, Romania. "Nicolae Simionescu" Institute of Tel.: (+401) 411.5240; Fax: (+401) 411.1143 Cellular Biology and Pathology E-mail: [email protected] J.Cell.Mol.Med. Vol 5, No 4, 2001

Introduction only for cholesterol, but also for many other nonsteroidal isoprenoidic compounds, inhibition of this Statins, inhibitors of 3-hydroxy-3-methylglutaryl- key enzyme may result in pleiotropic effects. They coenzyme A (HMG-CoA) reductase, have revolu- have been divided into two categories, involving: tionized the treatment of hypercholesterolemia. They directly lipids, or intracellular signaling pathways. are the most efficient agents for reducing plasma The first category includes: inhibition of cholesterol cholesterol, being also appreciated for their good to- biosynthesis, increased uptake and degradation of lerance. Angiographic studies have demonstrated low density lipoproteins (LDL), inhibition of the that these compounds reduce the progression and secretion of lipoproteins, inhibition of LDL may induce the regression of atherosclerosis. These oxidation, and inhibition of the scavenger receptors effects were translated in significant cardiovascular expression [3]. Statins modulate a series of processes morbidity and mortality reductions in many clinical leading to reduction of the accumulation of esterified trials (WOSCOPS, AFCAPS/TexCAPS, HS, CARE, cholesterol into macrophages, increase of endothelial LIPID, HPS) [1]. The beneficial effects of the HMG- NO synthetase, reduction of the inflammatory CoA reductase inhibitors are usually attributed to process, increased stability of the atherosclerotic their capacity to reduce the endogenous cholesterol plaques, restoration of platelets activity and of the synthesis, by competingly inhibiting the principal coagulation process [3]. enzyme involved [2]. Since mevalonate, the product In addition, statins can inhibit tumor cells growth of HMG CoA reductase reaction, is the precursor not and enhance intracellular calcium mobilization. It

Fig. 1 Chemical structure of the statins and HMG-CoA.

379 was observed that inhibitors of HMG-CoA reductase CYP 2C9 pathway, and pravastatin is metabolized induce a reduction of the formation of osteoclasts in differently [6]. The majority of the statins have a low rodents [3]. Human subjects treated with statins have circulation concentration: 12% for atorvastatin, 17% shown a reduction in the number of bone fractures [4]. for pravastatin, 20-30 % for fluvastatin, 5% for The discovery of statins has led to an important simvastatin and lovastatin. Cerivastatin has a progress in the primary and secondary prevention circulation distribution of more than 60%. of coronary heart disease. Although angiographic modifications following statin therapy were mo- Physico-chemical properties dest, clinical benefits that accompanied the therapy have been significant. Numerous clinical studies Pravastatin is extremely hydrophilic, fluvastatin has have correlated the reduction of blood cholesterol intermediar characteristics, lovastatin, simvastatin, induced by these compounds with the reduction of atorvastatin and cerivastatin are hydrofobic [7]. the number of major coronary events, as well as general mortality in coronary patients [1]. Specific activity

Atorvastatin, cerivastatin, fluvastatin and Classification of statins pravastatin are administered as active compounds (acid form). Lovastatin and simvastatin are There are a number of classification criteria for administered as inactive forms (lactone), which statins, including: 1) how they are obtained, 2) liver have to be enzymatically hydrolized to generate metabolism, 3) physico-chimical properties, 4) active forms [7]. specific activity.

How they are obtained Mechanisms for the action of statins

Some of the statins are obtained after fungal Mechanisms involving lipids fermentation: lovastatin (Mevacor), pravastatin (Lipostat, Pravachol) and simvastatin (Zocor), others Dyslipidemia and hypercholesterolemia are by synthesis: fluvastatin (Lescol), atorvastatin controled by the liver. Hepatocytes take up from the (Sortis, Lipitor), and cerivastatin (Baycol, Lipobay). circulation ~ 50% of LDL cholesterol. An increase It must be stressed that on August 8, 2001, Bayer in the activity of LDL receptor in hepatocytes could AG voluntarily withdrew cerivastatin (Baycol, be an efficient method to decrease plasma LDL Lipobay) from the world pharmaceutical market, cholesterol level. after 31 patients died by acute renal failure caused by rhabdomyolysis. FDA supported this decision. Inhibition of HMG CoA reductase As a result, only five statins are, at this moment, in Statins target hepatocytes and inhibit HMG-CoA clinical use: lovastatin, simvastatin, pravastatin, reductase, the enzyme that converts HMG-CoA into atorvastatin and fluvastatin. mevalonic acid, a cholesterol precursor. The statins do more than just compete with the normal substrate Liver metabolism in the enzymes active site. They alter the conformation of the enzyme when they bind to its All statins have the liver as target organ. The active site. This prevents HMG-CoA reductase from percentage of the dose retained by the liver is as attaining a functional structure. The change in follows: > 70% for fluvastatin and lovastatin, >80% conformation at the active site makes these drugs very for simvastatin and 46% for pravastatin [5]. There effective and specific. Binding of statins to HMG- are no available data for atorvastatin and cerivastatin. CoA reductase is reversible, and their affinity for the For their liver metabolism, lovastatin, simvastatin, enzyme is in the nanomolar range, as compared to the atorvastatin and cerivastatin follow the citocrom natural substrate, which has micromolar affinity [8]. P450 (CYP 3A4) pathway. Fluvastatin follows the The inhibition of HMG-CoA reductase determines

380 J.Cell.Mol.Med. Vol 5, No 4, 2001

Table 1 Role of prenylated proteins in cellular functioning [3].

* in mammalian cells, 0.5-1% of total cellular proteins are geranyl-geranylated. the reduction of intracellular cholesterol, inducing the Reduction of LDL susceptibility towards oxidation activation of a protease which slices the sterol At least 4 mechanisms were proposed to explain sta- regulatory element binding proteins (SREBPs) from tins’ antioxidant properties [16]. (1) The hypochole- the endoplasmic reticulum. SREBPs are translocated sterolemic effect, resulting in reduced lipoprotein at the level of the nucleus, where they increase the cholesterol, and thus, reduced level of oxidation gene expression for LDL receptor. The reduction of substrate [17]. (2) The decrease of cell oxygen pro- cholesterol in hepatocytes leads to the increase of duction, by inhibiting the generation of superoxide by hepatic LDL receptors, that determines the reduction macrophages. Recently, it was demonstrated that of circulating LDL and of its precursors (intermediate statins can attenuate the formation of superoxide an- density - IDL and very low density- VLDL ion in endothelial cells, by preventing the prenylation lipoproteins) [9]. All statins reduce LDL cholesterol of p21 Rac protein [18]. Statins can also prevent LDL non-liniarly, dose-dependent, and after administration oxidation by preserving the activity of the endoge- of a single daily dose [5]. Efficacy on triglyceride nous antioxidant system, like superoxide dismutase reduction parallels LDL cholesterol reduction [10]. [19]. (3) The binding of statins to phospholipids on the surface of lipoproteins (fluvastatin and lovastatin Direct effects of HMG CoA reductase inhibition bind to LDL phospholipids) preventing the diffusion Statins inhibit hepatic syntesis of apolipoprotein B- towards the lipoprotein core of free radicals generated 100, determining a reduction of the synthesis and during oxidative stress [16]. (4) The potent secretion of triglyceride rich lipoproteins [11] and an antioxidative potential of the metabolites (i.e. increase of receptors production for apolipoproteins atorvastatin and fluvastatin metabolites) also results B/E [12]. This can explain why atorvastatin and in lipoproteins protection from oxidation. simvastatin are capable of reducing LDL in patients with homozigous family hypercholesterolemia, Inhibition of the expression of type A scavenger re- where LDL receptors are not functional [13, 14]. ceptor in THP-1 cells and in human monocytes [20], Statins have a modest effect on HDL increase, and which decrease the receptor-mediated degradation of no influence on lipoprotein(s) concentration [15]. oxidised LDL. Statins can also reduce mRNA level

381 and CD36 expression on the cell surface, as well as The mevalonate pathway yields a series of LDL binding to human U937 monocytes [21]. isoprenoids which are vital for diverse cellular functions. These isoprenoids include: isopentenyl Mechanisms involving intracellular adenosine, present in some types of transfer RNA, signaling pathways dolichols required for glycoprotein synthesis, and poly-isoprenoid side chains of ubiquinone and Prenylated proteins and their role in cellular signaling hemeA, involved in electron transport [23]. A variety of proteins have covalently attached isoprenoid groups, mainly the C15 farnesyl and C20 geranylgeranyl residues. The most common isopreny- Beneficial effects of statins lation site in proteins is the C-terminal “CaaX”, where “C” is Cys, “a” is often an aliphatic aminoacid Effects on cholesterol esterification and its residue, and “X” is any aminoacid. Proteins are farne- accumulation in macrophages sylated when “X” is Ala, Met or Ser and gera- Studies done in mouse peritoneal macrophages nylgeranylated when “X” is Leu. In both cases the have shown that fluvastatin and simvastatin, but not prenyl group is enzymatically linked to the Cys sulfur pravastatin, inhibit cholesterol esterification atom via a thioether linkage. The “aaX” tripeptide is induced in cells by acetyl LDL [23]. The efficacy of then proteolytically excized and the newly exposed fluvastatin in inhibiting cholesterol esterification is terminal carboxyl group is esterified with a methyl more increased in cholesterol loaded cells than in group [22]. Many prenylated proteins are associated normal ones, effect that might be explained by the with intracellular membranes and mutating their Cys fact that the HMG CoA reductase is already prenylation sites blocks their membrane localization. inhibited in lipid-loaded cells, as compared with The hydrophobic prenyl group can act to anchor its unloaded ones [24]. attached protein to a membrane. Prenylated proteins may interact with specific membrane- bound receptor Effects on endothelial cell function proteins and hence prenylation also mediates protein- Endothelial dysfunction represents an early event in protein interactions [22]. the initiation of atherosclerotic lesion, induced by The complex process of cell signaling is very hypercholesterolemia. Nitric oxide (NO) regulates important for intercellular communication. the anti-atherosclerotic function of the endothelium Extracellular signaling molecules, which are water [1]. Hypercholesterolemia reduces the capacity of soluble and have high molecular weight need to endothelial cells to produce NO, probably due to bind to specific receptors on the cell surface, which the reduced availability of L-arginine, the transduce the extracellular signals into the cell by physiologic substrate of NO syntase, and determins intracellular signaling pathways (cascades). Many an increased degradation of NO. Cholesterol intracellular signaling molecules are prenylated reduction by statins leads to a significant increase proteins. The specific receptors on the cell surface of the endothelial function. The effect of statins on are associated with trimeric G protein, or have the endothelial function can be partially Ser/Thr/Tyr kinases activities. The trimeric G independent of the reduction of the lipid level. protein has a geranylgeranylated subunit (gamma), Simvastatin, as well as lovastatin, induce the allowing this signaling protein to be inserted in the transcriptional activation of eNOS gene in human cell membrane near specific membrane receptors endothelial cells in vitro [25]. Activation of eNOS and to receive extracellular signals, which are then by statins takes place post-translationally and is transfered to the secondary signaling molecules in prevented by isoprenoid derivatives, mevalonate the cell. Another important class of prenylated and geranylgeraniol [25]. The endothelial function signaling molecules are the components of Ras was increased in primates treated with pravastatin, family, which are farnesylated and intermediate the without the reduction of LDL cholesterol [25]. Ser/Thr/Tyr kinases activities of membrane Simvastatin administration to hyperlipemic receptors from the cell surface. The important role hamsters (HH) restores the antioxidant potential of of all these prenylated signaling molecules for the the serum [26]. Although the exact mechanism is living cell is presented in Table 1. not known, this effect may be the result of a

382 J.Cell.Mol.Med. Vol 5, No 4, 2001 decrease in cell oxygen production, binding of their prenylation and thus reducing the LDL to surface phospholipids or due to the inflammatory response. Statins diminish leukocytes antioxidant action of simvastatin metabolites [16]. recruitment in postcapillary venules, stimulated by In addition, experiments done by Simionescu et al., a lipid mediator (platelets activation factor-PAF or 2001 [26] showed that simvastatin reduced leukotriene B4) in hypercholesterolemic rats [31]. transcytosis of LDL and was able to restore the In addition, statins are capable to inhibit endothelial dependent relaxation, probably due to transendothelial migration and chemotaxisis of an increase in NO-synthesis. This latter assumption neutrophiles, which can explain the was based on two facts: (i) NO-synthase inhibitor, antiinflammatory effect of these compounds. L-NAME, inhibited the response of the arteries and Another antiinflammatory effect of statins on (ii) serum NO level increased in simvastatin-treated monocytes and macrophages was the decrease of HH. These data confirmed and extented previous the expression of intercellular adhesion molecule -1 reports indicating that statins upregulate eNOS and the secretion of interleukine-6 (IL-6), induced expression, and prevent native LDL-mediated by lipopolysacharides (LPS) [3]. down-regulation of eNOS expression. Simvastatin, as well as lovastatin, exerted a Effects on proliferation, migration and apoptosis protective, dose-dependent effect in an of arterial SMC experimental model of cerebral infarction, a All statins, except for pravastatin, reduce aortic neuroprotective effect mediated rather by the SMC proliferation [8]. Mevalonate, trans-farnesol increased production of eNOS, than by the reduced and trans-geranylgeraniol prevent the inhibitory level of cholesterol [27]. The neuroprotective effect effect of statins on SMC proliferation, suggesting of statins is completly absent in mice defficient in that this effect derives from the inhibition of the eNOS, indicating that the increased activity of mevalonate pathway [8]. Fluvastatin, simvastatin eNOS induced by statins is the mechanism by and cerivastatin, but not pravastatin, inhibit in a which these compounds protect against cerebral dose dependent manner, arterial SMC migration lesions [27]. Recent results obtained by Wagner et induced by fibrinogen [8]. al. (2000) [18] suggest that statins inhibit the Preclinical observations and in vitro studies formation of O2- by endothelial cells, producing suggest that apoptosis can modulate the arterial modifications in the NO-/ O2- balance, wall in restenotic or proliferative lesions, where modification leading to the restoration of the SMC are dominant [3]. It was reported that statins endothelial cell function. can induce apoptosis of vascular SMC in culture. Lesioned carotid arteries from rabbits that received Effects on the inflammatory process fluvastatin or atorvastatin, 5 days prior to lesion Adhesion to the endothelium and transendothelial induction, presented an increased number of diapedesis of circulating monocytes and of T apoptotic SMC [32]. lymphocytes represent key events in the atherosclerotic lesion formation [28]. Cytokines Effects on the stability of secreted by macrophages and lymphocytes can the atherosclerotic plaque modify endothelial function, smooth muscle cells Coronary events are the result of unstable (SMC) proliferation, collagen degradation and atherosclerotic lesion rupture and thrombus thrombosis [3]. Statins can reduce the expression formation [33]. The plaque instability, manifested and function of molecules on the leukocytes surface as an ulceration of the fibrous cap, the rupture of the [29]. Atorvastatin reduces the number of intimal plaque and internal hemorrhage, are characteristics macrophages, monocyte-chemoattractant protein-1 of the plaques with numerous lipid deposits and (MCP-1) and the activation of nuclear factor NFkB macrophages in the cap. Recently, it was in hypercholesterolemic rabbits [30]. Cytokines demonstrated that statins (fluvastatin, simvastatin) receptors are coupled to GTP-bound proteins, and can inhibit the gelatinolytic activity of the binding of leukocytes to the endothelium is metalloproteases, as well as their secretion by regulated by G protein. Statins can affect small human macrophages in culture [34]. Angiographic GTP-ases or trimeric G proteins, by preventing studies showed that statins reduce the progression

383 Fig. 2 Hypercholesterolemia favors entry of LDL particles into subendothelial space at lesion-prone arterial sites. Monocyte chemotactic protein-1 (MCP-1) and oxidized-LDL act as chemoattractants to direct accumulation of monocytes and their migration to the subendothelial space, where monocytes undergo phenotypic transformation into macrophages. Concurrently, oxigen free radicals modify LDL. Oxidatively modified LDL is taken up by nondownregulating macrophage receptors to form lipid-rich foam cells. Foam cells develop into fatty streaks, precursor of atherosclerotic plaques. Statins exihibit pleiotropic effects on many components of atherosclerosis that accompany hypercholesterolemia, including platelet coagulation abnormalities, abnormal endothelial function, and determinants of plaque thrombogenicity such as plaque inflammation and proliferation. and induce the regression of coronary as a function of the duration of simvastatin atherosclerosis, reduce the formation of new administration [36]. Although the duration of lesions and the incidence of coronary events [35]. treatment (6 weeks) was short as compared with Computer tomography provided evidence of the other clinical trials, simvastatin acted efficiently reduction in the volume of coronary calcified as a scavenger for peroxyl radicals. plaques after 12 months of statin treatment. It was concluded that alterations in the composition of Effects on platelet activation lesions confers an increased stability [1]. Hypercholesterolemia is associated with Other reports show that simvastatin treatment hypercoagulability, as well as with increased determines an increase of the antioxidant platelet activation [1]. An increased level of LDL potential in sera from stable (SA) and unstable determines an increased platelets reactivity, angina (UA) patients. Incubation of U937 associated with an increased thromboxan A2 macrophages and human aortic SMC with sera biosyntesis. Recently it was elucidated a new from simvastatin treated SA or UA patients led to mechanism by which platelets activity is a decreased accumulation of esterified cholesterol increased in hypercholesterolemia, due to LDL

384 J.Cell.Mol.Med. Vol 5, No 4, 2001 inhibiting the platelet antiport Na+/H+ [37]. In mevalonate and geranylgeraniol prevented the addition, platelet dependent thrombin generation effects, suggesting that a nonsterol intermediate is increased in hypercholesterolemic subjects, and is probably required for the prenylation of GTP- pravastatin treatment determines a restoration of binding proteins that control cytoskeletal thrombin formation. Statin therapy was reorganization, vesicle fusion and apoptosis, accompanied by a reduction of platelet processes involved in osteoclasts activation and aggregation induced by ADP, collagen or survival. In addition, it was demonstrated in vitro fibrinogen, as well as of thromboxan production, and in vivo in rodents, that statins enhance new in parallel with LDL cholesterol reduction. bone formation [3]. Statins administration is associated with a decrease of bone fracture risk in Effects on the coagulation process subjects over 50 years, probably because of the Primary and secondary prevention studies increase of the mineral density of the bones [4]. demonstrate that statin therapy reduces Thus, subjects with hyperlipidemia known to significantly thrombus formation. Recently, a link present increased risk for osteoporosis (mostly between the enhancement of endothelial post-menopausal women) could benefit from fibrinolytic system and the inhibition of statin therapy. mevalonate pathway was reported [38]. Statins action involves an increase in tPA activity, as well as a decrease in PAI-1 activity [38]. The tissue Adverse effects of statin therapy factor plays an important role in the initiation of the extrinsec coagulation pathway and it was Statins are generally well tolerated. The most localized in lipid-loaded macrophages from important adverse effects are liver and muscle atherosclerotic plaque. Recently, Colli et al. [39] toxicity. Myopathy can happen if inhibitors of have shown that lipophylic statins (simvastatin cytochrom P450 or other inhibitors of statins and fluvastatin) reduce the expression and metabolism are administered together with statins, activity of the tissue factor in human monocyte- determining the increase of their blood con- derived macrophages in culture, effect prevented centration. Such are the azole antifungals [40]. by the addition of mevalonate and trans- Fibrates and niacin enhance myopathy risk by a geranylgeraniol. mechanism not involving the increased statins blood concentration. Other risk factors are: hepatic Other beneficial effects of statins dysfunction, renal insufficiency, hypothyroidism, The fact that mevalonate plays a key role in cell advanced age and serious infections. proliferation and that many malignant cells The already discussed suspension of cerivastatin present an increased HMG-CoA reductase from the clinical use, because of fatal rhabdomyolysis activity, suggests that a selective inhibition of this in a number of patients confirms the muscle toxicity enzyme could lead to a new chemotherapy for of statins. On the other hand, it must be stressed that cancer disease [3]. cerivastatin is at least 10 times more myotoxic than Results obtained in vitro have shown that other statins and it was used in unusual high doses. statins can inhibit tumor cell growth, a fact confirmed by some in vivo experiments also. The obtained reduction of sterols synthesis by statins, Conclusions suggests that inhibition of tumor cell growth can be related to the reduction of nonsteroidal Statins are widely used for the treatment of isoprenoid compounds. This effect can influence hypercholesterolemia. They inhibit HMG-CoA Ras protein farnesylation, thus inhibiting Ras reductase competitively, reduce LDL levels more dependent tumor cell growth [3]. than other cholesterol-lowering drugs, and lower Recent experimental evidence support a role triglycerides levels in hypertriglyceridemic patients. for mevalonate pathway in murine and rabbit Statins have antiatherosclerotic effects, that correlate osteoclast formation and bone resorption. positively with the percent decrease in LDL Lovastatin inhibited both processes, while

385 cholesterol. In addition, they can exert antiathero- 10. Stein E.A., Lane M., Laskarzewski P., Comparison sclerotic effects independently of their hypolipide- of statins in hypertriglyceridemia, Am. J. Cardiol., mic action (fig. 2). Because the mevalonate metabo- 81: 66B-69B, 1998 lism generates a series of vital isoprenoids for diffe- 11. Ginsberg H.N., Le N.A., Short M.P., rent cellular functions, from cholesterol synthesis to Ramakrishnan R., Desnick R.J., Suppression of apolipoprotein B production during treatment of the control of cell growth and differentiation, HMG- cholesteryl ester storage disease with lovastatin: CoA reductase inhibition has beneficial pleiotropic implication for regulation of apolipoprotein B effects. Consequently, statins significantly reduce the synthesis, J. Clin. Invest., 80: 1692-1697, 1987 incidence of coronary events, both in primary and 12. Gaw A., Packard C.J., Murray E.F., Effects of secondary prevention, being the most efficient simvastatin on apoB metabolism and LDL hypolipidemic compounds that have reduced the rate subfraction distribution, Arterioscler. Thromb., 13: of mortality in coronary patients. Statins are well 170-89, 1993 tolerated and have an excellent safety record. Inde- 13. Marais A.D., Naumova R.P., Firth J.C., Penny C., pendent of their hypolipidemic properties, statins Neuwirth C.K., Thompson G.R., Decreased interfere with events involved in bone formation. In production of low density lipoprotein by atorvastatin after apheresis in homozygous familial addition, it was demonstrated that HMG-CoA hypercholesterolemia, J. Lipid Res., 38: 2071-2078, reductase inhibitors impede tumor cell growth. 1997 14. Raal F.J., Pilcher G.J., Illingworth D.R., Pappu A.S., Stein E.A., Laskarzewski P., Mitchel Y.B., Melino M.R., Expanded dose simvastatin is References effective in homozygous familial hypercholesterolemia, Atherosclerosis, 135: 249- 1. Vaughan C.J., Gotto A.M., Basson C.T., The 256, 1997 evolving role of statins in the management of 15. Kostner G.M., Gavish D., Leopold B., Bolzano K., atherosclerosis, J. Am. Coll. Cardiol., 35: 1-10, 2000 Weintraub M.S., Breslow J.L., HMG-CoA 2. Hunninghake D.B., HMG-CoA reductase reductase inhibitors lower LDL cholesterol without inhibitors, Curr. Opin. Lipidol., 3: 22-8, 1992 reducing Lp(a) levels, Circulation, 80: 1313-1319, 3. Bellosta S., Ferri N., Bernini F., Paoletti R., 1989 Corsini A., Non-lipid-related effects of statins, Ann. 16. Aviram M., Hussein O., Rosenblat M., Med., 32: 164-176, 2000 Schlezinger S., Hayek T., Keidar S., Interactions of 4. Meier C.R., Schlienger R.G., Kraenzlin M.E., platelets, macrophages, and lipoproteins in Schlegel B., Jick H., HMG-CoA reductase hypercholesterolemia: antiatherogenic effects of inhibitors and the risk of fractures, JAMA, 283: HMG-CoA reductase inhibitor therapy, J. 3205-3210, 2000 Cardiovasc. Pharmacol., 31: 39-45, 1998 5. Blum C.B., Comparison of properties of four 17. Hoffman R., Brook G.J., Aviram M., Hypoli- inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme pidemic drugs reduce lipoprotein susceptibility to A reductase, Am. J. Cardiol., 73: 3D-11D, 1994 undergo lipid peroxidation: in vitro and ex vivo 6. Lennernas H., Fager G., Pharmacodynamics and studies, Atherosclerosis, 93: 105-13, 1992 pharmacokinetics of the HMG-CoA reductase 18. Wagner A.H., Kohler T., Ruckschloss U., Just I., inhibitors: similarities and differences, Clin. Hecker M., Improvement of nitric oxide-dependent Pharmacokinet., 32: 403-425, 1997 vasodilatation by HMG-CoA reductase inhibitors 7. Blumenthal RS., Statins: Effective through attenuation of endothelial superoxide anion antiatherosclerotic therapy, Am. Heart. J., 139: 577- formation, Arterioscler. Thromb. Vasc. Biol., 20: 61- 83, 2000 9, 2000 8. Corsini A., Bellosta S., Baetta R., Fumagalli R., 19. Chen L., Haught W.H., Yang B., Preservation of Bernini F., New insights into the endogenous antioxidant activity and inhibition of pharmacodynamics and pharmacokinetic properties lipid peroxidation as common mechanisms of of statins, Pharmacol. Ther., 84: 413-28, 1999; antiatherosclerotic effects of vitamin E, lovastatin and 9. Sehayek E., Butbul E., Avner R., Enhanced amlodipine, J. Am. Coll. Cardiol., 30: 569-75, 1997 cellular metabolism of very low density lipoprotein 20. Hrboticky N., Draude G., Hapfelmeier G., Lorenz by simvastatin: a novel mechanism of action of R., Weber P.C., Lovastatin decreases the receptor- HMG-CoA reductase inhibitors, Eur. J. Clin. Invest., mediated degradation of acetylated and oxidized 24: 173-8, 1994 LDLs in human blood monocytes during early stage

386 J.Cell.Mol.Med. Vol 5, No 4, 2001

of differentiation into macrophages, Arterioscler. inflammation in a rabbit model of atherosclerosis, J. Throm. Vasc. Biol., 19: 1267-75, 1999 Am. Coll. Cardiol., 32: 2057-64, 1998 21. Pietsch A., Erl W., Lorenz R.L., Lovastatin reduces 31. Kimura M., Kurose I., Russell J., Granger D.N., the expression of the combined adhesion and Effects of fluvastatin on leukocyte-endothelial cell scavenger receptor CD36 in human monocytic cells, adhesion in hypercholesterolemic rats, Arterioscler. Biochem. Pharmacol., 52: 433, 1996 Thromb. Vasc. Biol., 17: 1521-6, 1997 22. Voet D., Voet J.G., Lipids and membranes. In: John 32. Baetta R., Donetti E., Comparato C., Calore M., Wiley & Sons, Inc., eds., Biochemistry, Second Rossi A., Teruzzi C., In vitro and in vivo apoptosis Edition, USA, 1995, pp. 315-316 by atorvastatin in stimulated smooth muscle cells, 23. Bernini F., Didoni G., Bonfadini G., Bellosta S., Pharmacol. Res., 36: 115-21, 1997 Fumagalli R., Requirement for mevalonate in 33. Falk E., Shah P.K., Fuster V., Coronary plaque acetylated LDL induction of cholesterol disruption, Circulation 92: 657-71, 1995 esterification in macrophages, Atherosclerosis, 104: 34. Bellosta S., Via D., Canavesi M., Pfister P., 19-26, 1993 Fumagalli R., Paoletti R., HMG-CoA reductase 24. Bernini F., Scurati N., Bonfadini G., Fumagalli inhibitors reduce MMP-9 secretion by macrophages, R., HMG-CoA reductase inhibitors reduce acetyl Arterioscler. Thromb. Vasc. Biol., 18: 1671-8, 1998 LDL endocytosis in mouse peritoneal macrophages, 35. Ballantyne C.M., Herd J.A,. Dunn J.K., Jones Arterioscler. Thromb. Vasc. Biol., 15: 1352-8, 1995 P.H., Farmer J.A., Gotto A.M.J., Effects of lipid 25. Laufs U., Fata V.L., Plutzky J., Liao J.K., lowering therapy on progression of coronary and Upregulation of endothelial nitric oxide synthase by carotid artery disease, Curr. Opin. Lipidol., 8: 354- HMG-CoA reductase inhibitors, Circulation, 97: 361, 1997 1129-1135, 1998 36. Stancu C., Niculescu L., Toporan D., Sima A., 26. Simionescu M., Stancu C., Costache G., Sima A., Ioan A., Simionescu M., Statins produce anti- Endothelial cell response to hyperlipemia: atherosclerotic effects in coronary heart disease activation- dysfunction- injury; the protective role of patients, Proceedings of the Romanian Academy, simvastatin, Gen. Pharm., 2001 (in press) 2001 (in press) 27. Endres M., Laufs U., Huang Z., Nakamura T., 37. Nofer J-R., Tepel M., Kehrel B., Low-density Huang P., Moskowitz M.A., Liao J.K., Stroke lipoproteins inhibit the Na+/H+ antiport in human protection by 3-hydroxy-3-methylglutaryl (HMG)- platelets: a novel mechanism enhancing platelet CoA reductase inhibitors mediated by endothelial activity in hypercolesterolemia, Circulation, 95: nitric oxide synthase, Proc. Natl. Acad. Sci. USA, 95: 1370-7, 1997 8880-8885, 1998 38. Essig M., Nguyen G., Prie D., Escoubet B., Sraer 28. Ross R., Atherosclerosis - an inflammatory disease, J.D., Friedlander G., 3-hydroxy-3-methylglutaryl N. Engl. J. Med. 340:115-26, 1999 coenzyme A reductase inhibitors increase 29. Weber C., Erl W., Weber K.S.C., Weber P.C., fibrinolytic activity in rat aortic endothelial cells, HMG-CoA reductase inhibitors decrease CD11b Circ. Res., 83: 683-90, 1998 expression and CD11b-dependent adhesion of 39. Colli S., Eligini S., Lalli M., Camera M., Paoletti monocytes to endothelium and reduce increased R., Tremoli E., Vastatins inhibit tissue factor in adhesiveness of monocytes isolated from patients cultured human macrophages: a novel mechanism of with hypercholesterolemia, J. Am. Coll. Cardiol., protection against atherosclerosis, Arterioscler. 30: 1212-7, 1997 Thromb. Vasc. Biol., 17: 265-72, 1997 30. Bustos C., Hernandez-Presa H., Ortego M., Tunon 40. Maron D.J., Fazio S., Linton M.F., Current J., Ortega L., Perez F., HMG-CoA reductase perspectives on statins, Circulation, 101: 207-213, inhibition by atorvastatin reduces neointimal 2000

387