Isoprenoids as mediators of the biological effects of statins

Targeting the mevalonate cascade as a new therapeutic approach in heart disease, cancer and pulmonary disease

The cholesterol biosynthesis pathway, also known as the mevalonate (MVA) pathway, is an essential cellular pathway that is involved in diverse cell functions. The enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMGCR) is the rate-limiting step in cholesterol biosynthesis and catalyzes the conversion of HMG-CoA to MVA. Given its role in cholesterol and isoprenoid biosynthesis, the regulation of HMGCR has been intensely investigated. Because all cells require a steady supply of MVA, both the sterol (i.e. cholesterol) and non-sterol (i.e. isoprenoid) products of MVA metabolism exert coordinated feedback regulation on HMGCR through different mechanisms. The proper functioning of HMGCR as the proximal enzyme in the MVA pathway is essential under both normal physiologic conditions and in many diseases given its role in cell cycle pathways and cell proliferation, cholesterol biosynthesis and metabolism, cell cytoskeletal dynamics and stability, cell membrane structure and fluidity, mitochondrial function, proliferation, and cell fate. The blockbuster statin drugs ('statins') directly bind to and inhibit HMGCR, and their use for the past thirty years has revolutionized the treatment of hypercholesterolemia and cardiovascular diseases, in particular coronary heart disease. Initially thought to exert their effects through cholesterol reduction, recent evidence indicates that statins also have pleiotropic immunomodulatory properties independent of cholesterol lowering. In this review we will focus on the therapeutic applications and mechanisms involved in the MVA cascade including Rho GTPase and Rho kinase (ROCK) signaling, statin inhibition of HMGCR, geranylgeranyltransferase (GGTase) inhibition, and farnesyltransferase (FTase) inhibition in cardiovascular disease, pulmonary diseases (e.g. asthma and chronic obstructive pulmonary disease (COPD)), and cancer.

Statins and autoimmunity

Statins have immunomodulatory effects. Hence, they could be advantageous for different reasons. First, statins can serve as adjunct therapy in autoimmune diseases. Second, they may play a role in the prevention of accelerated atherosclerosis in the same population. In this review, we discuss the mechanisms of immune regulation by statins and review the literature for their benefit in many autoimmune diseases. In these studies, statins lead to an improvement in the disease activity scores in rheumatoid arthritis patients; a reduction in prothrombotic factors in anti-phospholipid syndrome patients; changes in vasculature, proteinuria, and cardiac events in systemic lupus erythematosus patients; changes in vasculature and proteinuria in patients with vasculitis; disease activity scores in ankylosing spondylitis; and finally vascular changes in patients with systemic sclerosis. Hence, these studies suggest that statins could be used as adjuncts to standard therapy due to their anti-inflammatory, immunomodulatory, and anti-thrombogenic effects. More evidence-based research is required to determine whether statin regimens will become the standard of care in patients with autoimmune diseases.

Protein prenylation and synaptic plasticity: implications for Alzheimer's disease

Protein prenylation is an important lipid posttranslational modification of proteins. It includes protein farnesylation and geranylgeranylation, in which the 15-carbon farnesyl pyrophosphate or 20-carbon geranylgeranyl pyrophosphate is attached to the C-terminus of target proteins, catalyzed by farnesyl transferase or geranylgeranyl transferases, respectively. Protein prenylation facilitates the anchoring of proteins into the cell membrane and mediates protein-protein interactions. Among numerous proteins that undergo prenylation, small GTPases represent the largest group of prenylated proteins. Small GTPases are involved in regulating a plethora of cellular functions including synaptic plasticity. The prenylation status of small GTPases determines the subcellular locations and functions of the proteins. Dysregulation or dysfunction of small GTPases leads to the development of different types of disorders. Emerging evidence indicates that prenylated proteins, in particular small GTPases, may play important roles in the pathogenesis of Alzheimer's disease. This review focuses on the prenylation of Ras and Rho subfamilies of small GTPases and its relation to synaptic plasticity and Alzheimer's disease.

Interplay of mevalonate and Hippo pathways regulates RHAMM transcription via YAP to modulate breast cancer cell motility

Expression of receptor for hyaluronan-mediated motility (RHAMM), a breast cancer susceptibility gene, is tightly controlled in normal tissues but elevated in many tumors, contributing to tumorigenesis and metastases. However, how the expression of RHAMM is regulated remains elusive. Statins, inhibitors of mevalonate metabolic pathway widely used for hypercholesterolemia, have been found to also have antitumor effects, but little is known of the specific targets and mechanisms. Moreover, Hippo signaling pathway plays crucial roles in organ size control and cancer development, yet its downstream transcriptional targets remain obscure. Here we show that RHAMM expression is regulated by mevalonate and Hippo pathways converging onto Yes-associated protein (YAP)/TEAD, which binds RHAMM promoter at specific sites and controls its transcription and consequently breast cancer cell migration and invasion (BCCMI); and that simvastatin inhibits BCCMI via targeting YAP-mediated RHAMM transcription. Required for ERK phosphorylation and BCCMI, YAP-activated RHAMM transcription is dependent on mevalonate and sensitive to simvastatin, which modulate RHAMM transcription by modulating YAP phosphorylation and nuclear-cytoplasmic localization. Further, modulation by mevalonate/simvastatin of YAP-activated RHAMM transcription requires geranylgeranylation, Rho GTPase activation, and actin cytoskeleton rearrangement, but is largely independent of MST and LATS kinase activity. These findings from in vitro and in vivo investigations link mevalonate and Hippo pathways with RHAMM as a downstream effector, a YAP-transcription and simvastatin-inhibition target, and a cancer metastasis mediator; uncover a mechanism regulating RHAMM expression and cancer metastases; and reveal a mode whereby simvastatin exerts anticancer effects; providing potential targets for cancer therapeutic agents.

Evaluation of the effect of genetic variation on the relationship between statins, cardiovascular disease and cancer

Statins are a class of medications that are competitive inhibitors of Hydroxy Methyl Glutaryl Co-enzyme A (HMG-CoA) reductase which is the rate-limiting enzyme in the cholesterol bio-synthesis pathway. As a result, statins lower total cholesterol and low density lipoprotein (LDL) cholesterol thus impacting cardiovascular mortality. The downstream effects of statins are not limited to inhibition of cholesterol synthesis alone. Statins have anti-inflammatory effects thought to be important in the setting of acute myocardial infarction which also may be a mechanism involved in anti-carcinogenic properties of statins. Furthermore, statin inhibition of the mevalonate pathway may impact Ras and RhoGTPases that are important in cell proliferation, migration and apoptosis. These alterations may also play a role in the anti-cancer effect of statins. In this article we will review the literature on how genetic variation modifies the effect of statins on the risk of cardiovascular disease and how genetic variation may impact the relationship between statins and the risk of a number of different cancers.

Statins as modulators of regulatory T-cell biology

Statins are pharmacological inhibitors of the activity of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), an enzyme responsible for the synthesis of cholesterol. Some recent experimental studies have shown that besides their effects on the primary and secondary prevention of cardiovascular diseases, statins may also have beneficial anti-inflammatory effects through diverse mechanisms. On the other hand, the induction and activity of regulatory T cells (Treg) are key processes in the prevention of pathology during chronic inflammatory and autoimmune diseases. Hence, strategies oriented towards the therapeutic expansion of Tregs are gaining special attention among biomedical researchers. The potential effects of statins on the biology of Treg are of particular importance because of their eventual application as in vivo inducers of Treg in the treatment of multiple conditions. In this paper we review the experimental evidence pointing out to a potential effect of statins on the role of regulatory T cells in different conditions and discuss its potential clinical significance.

Prospective analysis of association between statin use and breast cancer risk in the women's health initiative

BACKGROUND

Statins are a class of cholesterol-lowering drugs that affect many intracellular pathways that may have implications for chemoprevention against cancer. Epidemiologic data on statins and breast cancer are conflicting. We analyzed updated data from the Women's Health Initiative (WHI) to assess the relationship between statins and breast cancer risk.

METHODS

The population included 154,587 postmenopausal women ages 50 to 79 years, with 7,430 pathologically confirmed cases of breast cancer identified over an average of 10.8 (SD, 3.3) years. Information on statins was collected at baseline and years one, three, six, and nine. Self- and interviewer-administered questionnaires were used to collect information on risk factors. Cox proportional hazards regression was used to calculate HRs with 95% confidence intervals (CI) to evaluate the relationship between statin use and cancer risk. Statistical tests were two-sided.

RESULTS

Statins were used by 11,584 (7.5%) women at baseline. The annualized rate of breast cancer was 0.42% among statin users and 0.42% among nonusers. The multivariable adjusted HR of breast cancer for users versus nonusers was 0.94 (95% CI, 0.83-1.06). In the multivariable-adjusted, time-dependent model, the HR for simvastatin was 0.87 (95% CI, 0.71-1.07). There was no significant trend by overall duration of use (P value for trend 0.68). There was no effect of tumor stage, grade, or hormone receptor status.

CONCLUSION

Overall, statins were not associated with breast cancer risk.

IMPACT

Our study is one of the largest prospective observational studies on this topic, and substantially adds to the literature suggesting no relationship between statins and breast cancer risk.

Stimulation of osteoclast formation by RANKL requires interferon regulatory factor-4 and is inhibited by simvastatin in a mouse model of bone loss

Diseases of bone loss are a major public health problem. Here, we report the novel therapeutic action of simvastatin in osteoclastogenesis and osteoprotection, demonstrated by the ability of simvastatin to suppress osteoclast formation in vitro and in vivo. We found that in vitro, IRF4 expression is upregulated during osteoclast differentiation induced by RANKL (receptor activator of nuclear factor-κB ligand), while simvastatin blocks RANKL-induced osteoclastogenesis and decreases expression of NFATc1 (nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1), IRF4 and osteoclast markers. We also show that IRF4 acts in cooperation with NFATc2 and NF-κB on the promoter region of NFATc1 to accelerate its initial transcription during the early stage of osteoclastogenesis. Moreover, our study using IRF4 siRNA knockdown directly demonstrates the requirement for IRF4 in NFATc1 mRNA transcription and its necessity in RANKL-induced osteoclast differentiation. Our results suggest that the reduction in osteoclastogenesis is partly due to the inhibition of IRF4 production in RANKL-induced osteoclast differentiation. To investigate the in vivo effects of simvastatin in RANKL-treated mice, we examined the bone mineral density (BMD) of a mouse model of bone loss, and found that simvastatin significantly reduced bone loss by suppressing osteoclast numbers in vivo, even in the presence of high concentrations of RANKL. These results suggest that the depletion of osteoclasts is not due to the reduction in RANKL produced by osteoblasts in vivo. The results are consistent with the hypothesis that simvastatin blocks RANKL-induced IRF4 expression in osteoclastogenesis. We propose that the expression of IRF4 by osteoclasts could be a promising new therapeutic target in bone-loss diseases.

Simvastatin inhibits smoke-induced airway epithelial injury: implications for COPD therapy

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death. The statin drugs may have therapeutic potential in respiratory diseases such as COPD, but whether they prevent bronchial epithelial injury is unknown. We hypothesised that simvastatin attenuates acute tobacco smoke-induced neutrophilic lung inflammation and airway epithelial injury. Spontaneously hypertensive rats were given simvastatin (20 mg·kg(-1) i.p.) daily for either 7 days prior to tobacco smoke exposure and during 3 days of smoke exposure, or only during tobacco smoke exposure. Pretreatment with simvastatin prior to and continued throughout smoke exposure reduced the total influx of leukocytes, neutrophils and macrophages into the lung and airways. Simvastatin attenuated tobacco smoke-induced cellular infiltration into lung parenchymal and airway subepithelial and interstitial spaces. 1 week of simvastatin pretreatment almost completely prevented smoke-induced denudation of the airway epithelial layer, while simvastatin given only concurrently with the smoke exposure had no effect. Simvastatin may be a novel adjunctive therapy for smoke-induced lung diseases, such as COPD. Given the need for statin pretreatment there may be a critical process of conditioning that is necessary for statins' anti-inflammatory effects. Future work is needed to elucidate the mechanisms of this statin protective effect.

Role of Rac1-mineralocorticoid-receptor signalling in renal and cardiac disease

The Rho-family small GTPase, Ras-related C3 botulinum toxin substrate 1 (Rac1), has been implicated in renal and cardiac disease. Rac1 activation in podocytes has been shown in several models of proteinuric kidney disease and a concept involving motile podocytes has been proposed. Evidence also exists for a critical role of Rac1-mediated oxidative stress in cardiac hypertrophy, cardiomyopathy and arrhythmia, and of the aldosterone-mineralocorticoid-receptor system in proteinuria and cardiac disorders. However, plasma aldosterone concentrations are not always increased in these conditions and the mechanisms of mineralocorticoid-receptor overactivation are difficult to determine. Using knockout mice, we identified a novel mechanism of Rac1-mediated podocyte impairment; Rac1 potentiates the activity of the mineralocorticoid receptor, thereby accelerating podocyte injury. We subsequently demonstrated that the Rac1-mineralocorticoid-receptor pathway contributes to ligand-independent mineralocorticoid-receptor activation in several animal models of kidney and cardiac injury. Hyperkalaemia is a major concern associated with the use of mineralocorticoid-receptor antagonists; however, agents that modulate the activity of the Rac1-mineralocorticoid-receptor pathway in target cells, such as cell-type-specific Rac inhibitors and selective mineralocorticoid-receptor modulators, could potentially be novel therapeutic candidates with high efficacy and a low risk of adverse effects in patients with renal and cardiac diseases.

A genetic and pharmacological analysis of isoprenoid pathway by LC-MS/MS in fission yeast

Currently, statins are the only drugs acting on the mammalian isoprenoid pathway. The mammalian genes in this pathway are not easily amenable to genetic manipulation. Thus, it is difficult to study the effects of the inhibition of various enzymes on the intermediate and final products in the isoprenoid pathway. In fission yeast, antifungal compounds such as azoles and terbinafine are available as inhibitors of the pathway in addition to statins, and various isoprenoid pathway mutants are also available. Here in these mutants, treated with statins or antifungals, we quantified the final and intermediate products of the fission yeast isoprenoid pathway using liquid chromatography-mass spectrometry/mass spectrometry. In hmg1-1, a mutant of the gene encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), ergosterol (a final sterol product), and squalene (an intermediate pathway product), were decreased to approximately 80% and 10%, respectively, compared with that of wild-type cells. Consistently in wild-type cells, pravastatin, an HMGR inhibitor decreased ergosterol and squalene, and the effect was more pronounced on squalene. In hmg1-1 mutant and in wild-type cells treated with pravastatin, the decrease in the levels of farnesyl pyrophosphate and geranylgeranyl pyrophosphate respectively was larger than that of ergosterol but was smaller than that of squalene. In Δerg6 or Δsts1 cells, mutants of the genes involved in the last step of the pathway, ergosterol was not detected, and the changes of intermediate product levels were distinct from that of hmg1-1 mutant. Notably, in wild-type cells miconazole and terbinafine only slightly decreased ergosterol level. Altogether, these studies suggest that the pleiotropic phenotypes caused by the hmg1-1 mutation and pravastatin might be due to decreased levels of isoprenoid pyrophosphates or other isoprenoid pathway intermediate products rather than due to a decreased ergosterol level.

The role of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors (statins) in modern rheumatology

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase commonly known as statins are widely used for treating hypercholesterolemia. However, there is much evidence to suggest that statins may have other properties in addition to their cholesterol-lowering effect. In particular, statins may neutralize post-translational prenylation of vitally important regulatory small GTPases, which are involved in several processes such as tissue fibrosis, cell maturation, apoptosis, immune cell maturation, and immune response. The beneficial effect of statins has been reported in animal and in vitro models as well as in some clinical studies. As they have an acceptable safety profile, statins may be considered, in selected cases, as a valuable concomitant therapy in the treatment of rheumatic and autoimmune disorders.

Dose-dependency in pleiotropic effects of atorvastatin

Statins are recognized as the principal and most effective class of drugs for reducing serum cholesterol levels and, therefore, significantly reducing cardiovascular events and mortality. Statins may have a wide range of beneficial biological effects in addition to lipid lowering, a phenomenon commonly termed a 'pleiotropic effect'. However, the dose-dependency of these effects remains unclear. The present study evaluated whether atorvastatin, a potent statin, ameliorates the serum markers of pleiotropic effects, with a focus on dose-dependency. The pleiotropic effects of treatment with atorvastatin 5 mg/day and 10 mg/day for six months each in 15 patients with primary hypercholesterolemia were assessed in a prospective, randomized, open-label, crossover, single-centre study. Atorvastatin treatment dose-dependently decreased a serum marker of oxidative stress as well as the serum low-density lipoprotein cholesterol level. However, serum markers of inflammation and fibrinolysis decreased independently of dose. In conclusion, the dose-dependency of atorvastatin's pleiotropic effects differs among individual biological effects.

Hepatic and pulmonary toxicogenomic profiles in mice intratracheally instilled with carbon black nanoparticles reveal pulmonary inflammation, acute phase response, and alterations in lipid homeostasis

Global pulmonary and hepatic messenger RNA profiles in adult female C57BL/6 mice intratracheally instilled with carbon black nanoparticles (NPs) (Printex 90) were analyzed to identify biological perturbations underlying systemic responses to NP exposure. Tissue gene expression changes were profiled 1, 3, and 28 days following exposure to 0.018, 0.054, and 0.162 mg Printex 90 alongside controls. Pulmonary response was marked by increased expression of inflammatory markers and acute phase response (APR) genes that persisted to day 28 at the highest exposure dose. Genes in the 3-hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase pathway were increased, and those involved in cholesterol efflux were decreased at least at the highest dose on days 1 and 3. Hepatic responses mainly consisted of the HMG-CoA reductase pathway on days 1 (high dose) and 28 (all doses). Protein analysis in tissues and plasma of 0.162 mg Printex 90-exposed mice relative to control revealed an increase in plasma serum amyloid A on days 1 and 28 (p < 0.05), decreases in plasma high-density lipoprotein on days 3 and 28, an increase in plasma low-density lipoprotein on day 28 (p < 0.05), and marginal increases in total hepatic cholesterol on day 28 (p = 0.06). The observed changes are linked to APR. Although further research is needed to establish links between observations and the onset and progression of systemic disorders, the present study demonstrates the ability of NPs to induce systemic effects.

The effect of rosuvastatin in a murine model of influenza A infection

RATIONALE

HMG-CoA reductase inhibitors such as rosuvastatin may have immunomodulatory and anti-inflammatory effects that may reduce the severity of influenza A infection. We hypothesized that rosuvastatin would decrease viral replication, attenuate lung injury, and improve mortality following influenza A infection in mice.

METHODS

C57Bl/6 mice were treated daily with rosuvastatin (10 mg/kg/day) supplemented in chow (or control chow) beginning three days prior to infection with either A//Udorn/72 [H3N2] or A/WSN/33 [H1N1] influenza A virus (1×10(5) pfu/mouse). Plaque assays were used to examine the effect of rosuvastatin on viral replication in vitro and in the lungs of infected mice. We measured cell count with differential, protein and cytokines in the bronchoalveolar lavage (BAL) fluid, histologic evidence of lung injury, and wet-to-dry ratio on Day 1, 2, 4, and 6. We also recorded daily weights and mortality.

RESULTS

The administration of rosuvastatin had no effect on viral clearance of influenza A after infection. Weight loss, lung inflammation and lung injury severity were similar in the rosuvastatin and control treated mice. In the mice infected with influenza A (A/WSN/33), mortality was unaffected by treatment with rosuvastatin.

CONCLUSIONS

Statins did not alter the replication of influenza A in vitro or enhance its clearance from the lung in vivo. Statins neither attenuated the severity of influenza A-induced lung injury nor had an effect on influenza A-related mortality. Our data suggest that the association between HMG CoA reductase inhibitors and improved outcomes in patients with sepsis and pneumonia are not attributable to their effects on influenza A infection.

Isoprenoids and related pharmacological interventions: potential application in Alzheimer's disease

Two major isoprenoids, farnesyl pyrophosphate and geranylgeranyl pyrophosphate, serve as lipid donors for the posttranslational modification (known as prenylation) of proteins that possess a characteristic C-terminal motif. The prenylation reaction is catalyzed by prenyltransferases. The lipid prenyl group facilitates to anchor the proteins in cell membranes and mediates protein-protein interactions. A variety of important intracellular proteins undergo prenylation, including almost all members of small GTPase superfamilies as well as heterotrimeric G protein subunits and nuclear lamins. These prenylated proteins are involved in regulating a wide range of cellular processes and functions, such as cell growth, differentiation, cytoskeletal organization, and vesicle trafficking. Prenylated proteins are also implicated in the pathogenesis of different types of diseases. Consequently, isoprenoids and/or prenyltransferases have emerged as attractive therapeutic targets for combating various disorders. This review attempts to summarize the pharmacological agents currently available or under development that control isoprenoid availability and/or the process of prenylation, mainly focusing on statins, bisphosphonates, and prenyltransferase inhibitors. Whereas statins and bisphosphonates deplete the production of isoprenoids by inhibiting the activity of upstream enzymes, prenyltransferase inhibitors directly block the prenylation of proteins. As the importance of isoprenoids and prenylated proteins in health and disease continues to emerge, the therapeutic potential of these pharmacological agents has expanded across multiple disciplines. This review mainly discusses their potential application in Alzheimer's disease.

Prospective analysis of association between use of statins or other lipid-lowering agents and colorectal cancer risk

PURPOSE

To determine whether 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) are associated with a decreased risk of colorectal cancer.

METHODS

The population included 159,219 postmenopausal women enrolled in the Women's Health Initiative in which 2000 pathologically confirmed cases of colorectal cancer were identified during an average of 10.7 (S.D. 2.9) years. Information on statins was collected at baseline and years 1, 3, 6, and 9. Self- and interviewer-administered questionnaires were used to collect information on other risk factors. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated by the use of Cox proportional hazards regression to evaluate the relationship between statin use and risk. Statistical tests were two-sided.

RESULTS

Statins were used by 12,030 (7.6%) women at baseline. The annualized colorectal cancer rate was 0.13% among users and 0.12% among nonusers. The multivariable adjusted HR for users versus nonusers was 0.99 (95% confidence interval [CI], 0.83-1.20, p = .95), and 0.79 (95% CI, 0.56-1.11) for users of ≥3 years. In the multivariable adjusted time-dependent model, the HR for lovastatin was 0.62 (95% CI, 0.39-0.99). There was no effect of tumor location, stage or grade.

CONCLUSIONS

There was a reduction in colorectal cancer risk associated with lovastatin and a nonsignificant association with longer duration of use.

The mevalonate pathway in C. elegans

The mevalonate pathway in human is responsible for the synthesis of cholesterol and other important biomolecules such as coenzyme Q, dolichols and isoprenoids. These molecules are required in the cell for functions ranging from signaling to membrane integrity, protein prenylation and glycosylation, and energy homeostasis. The pathway consists of a main trunk followed by sub-branches that synthesize the different biomolecules. The majority of our knowledge about the mevalonate pathway is currently focused on the cholesterol synthesis branch, which is the target of the cholesterol-lowering statins; less is known about the function and regulation of the non-cholesterol-related branches. To study them, we need a biological system where it is possible to specifically modulate these metabolic branches individually or in groups. The nematode Caenorhabditis elegans (C. elegans) is a promising model to study these non-cholesterol branches since its mevalonate pathway seems very well conserved with that in human except that it has no cholesterol synthesis branch. The simple genetic makeup and tractability of C. elegans makes it relatively easy to identify and manipulate key genetic components of the mevalonate pathway, and to evaluate the consequences of tampering with their activity. This general experimental approach should lead to new insights into the physiological roles of the non-cholesterol part of the mevalonate pathway. This review will focus on the current knowledge related to the mevalonate pathway in C. elegans and its possible applications as a model organism to study the non-cholesterol functions of this pathway.

Simvastatin inhibits TGFβ1-induced fibronectin in human airway fibroblasts

Background

Bronchial fibroblasts contribute to airway remodelling, including airway wall fibrosis. Transforming growth factor (TGF)-β1 plays a major role in this process. We previously revealed the importance of the mevalonate cascade in the fibrotic response of human airway smooth muscle cells. We now investigate mevalonate cascade-associated signaling in TGFβ1-induced fibronectin expression by bronchial fibroblasts from non-asthmatic and asthmatic subjects.

Methods

We used simvastatin (1-15 μM) to inhibit 3-hydroxy-3-methlyglutaryl-coenzyme A (HMG-CoA) reductase which converts HMG-CoA to mevalonate. Selective inhibitors of geranylgeranyl transferase-1 (GGT1; GGTI-286, 10 μM) and farnesyl transferase (FT; FTI-277, 10 μM) were used to determine whether GGT1 and FT contribute to TGFβ1-induced fibronectin expression. In addition, we studied the effects of co-incubation with simvastatin and mevalonate (1 mM), geranylgeranylpyrophosphate (30 μM) or farnesylpyrophosphate (30 μM).

Results

Immunoblotting revealed concentration-dependent simvastatin inhibition of TGFβ1 (2.5 ng/ml, 48 h)-induced fibronectin. This was prevented by exogenous mevalonate, or isoprenoids (geranylgeranylpyrophosphate or farnesylpyrophosphate). The effects of simvastatin were mimicked by GGTI-286, but not FTI-277, suggesting fundamental involvement of GGT1 in TGFβ1-induced signaling. Asthmatic fibroblasts exhibited greater TGFβ1-induced fibronectin expression compared to non-asthmatic cells; this enhanced response was effectively reduced by simvastatin.

Conclusions

We conclude that TGFβ1-induced fibronectin expression in airway fibroblasts relies on activity of GGT1 and availability of isoprenoids. Our results suggest that targeting regulators of isoprenoid-dependent signaling holds promise for treating airway wall fibrosis.

The role of atorvastatin in regulating the immune response leading to vascular damage in a model of Kawasaki disease

Superantigens have been implicated in a number of diseases including Kawasaki disease (KD), a multi-system vasculitis resulting in coronary artery aneurysms. We have characterized a murine disease model in which coronary arteritis is induced by a novel superantigen found in Lactobacillus casei cell wall extract (LCWE). Using this animal model of KD, we have identified three pathogenic steps leading to coronary artery aneurysm formation. These steps include T cell activation and proliferation, production of the proinflammatory cytokine tumour necrosis factor (TNF)-α and up-regulation of matrix metalloproteinase 9 (MMP-9), an elastolytic protease. In addition to their cholesterol-lowering effects, 3-hydroxy-3-methylglutaryl (HMG) coenzyme A (CoA) reductase inhibitors (statins) have pleotropic immunomodulatory properties. Thus, we examined the effect of atorvastatin in modulating each of these three critical pathogenic processes leading to aneurysm formation in the disease model. Atorvastatin inhibited lymphocyte proliferation in response to superantigen stimulation in a dose-dependent manner. This inhibition was also observed for production of soluble mediators of inflammation including interleukin (IL)-2 and TNF-α. The inhibitory effect on proliferation was rescued completely by mevalonic acid, confirming that the mechanism responsible for this inhibitory activity on immune activation was inhibition of HMG-CoA reductase. Similarly, TNF-α-induced MMP-9 production was reduced in a dose-dependent manner in response to atorvastatin. Inhibition of extracellular-regulated kinase (ERK) phosphorylation appears to be the mechanism responsible for inhibition of MMP-9 production. In conclusion, atorvastatin is able to inhibit critical steps known to be important in the development of coronary aneurysms, suggesting that statins may have therapeutic benefit in patients with KD.

Modeling cholesterol metabolism by gene expression profiling in the hippocampus

An important part of the challenge of building models of biochemical reactions is determining reaction rate constants that transform substrates into products. We present a method to derive enzymatic kinetic values from mRNA expression levels for modeling biological networks without requiring further tuning. The core metabolic reactions of cholesterol in the brain, particularly in the hippocampus, were simulated. To build the model the baseline mRNA expression levels of genes involved in cholesterol metabolism were obtained from the Allen Mouse Brain Atlas. The model is capable of replicating the trends of relative cholesterol levels in Alzheimer's and Huntington's diseases; and reliably simulated SLOS, desmosterolosis, and Dhcr14/Lbr knockout studies. A sensitivity analysis correctly uncovers the Hmgcr, Idi2 and Fdft1 sites that regulate cholesterol homeostasis. Overall, our model and methodology can be used to pinpoint key reactions, which, upon manipulation, may predict altered cholesterol levels and reveal insights into potential drug therapy targets under diseased conditions.

Statins: cardiovascular risk reduction in percutaneous coronary intervention-basic and clinical evidence of hyperacute use of statins

Reduction of LDL-cholesterol concentration in serum, blocking the isoprenylation of GTPases and the activation of myocyte-protective enzyme systems are three mechanisms that currently explain the lipid and non-lipid effects of statins. However, the decrease of LDL-cholesterol, the reduction of inflammation biomarkers and even the atheroregresion, as surrogate effects to the mechanisms of action of statins would be irrelevant if not accompanied by a significant decrease in the incidence of cardiovascular events. Statins like no other pharmacological group have proven to reduce the incidence of cardiovascular events and prolong life in any clinical scenario. This article review the basic and clinical evidence that support a new indication for HMG-CoA reductase inhibitors "pharmacological myocardial preconditioning before anticipated ischemia" or hyperacute use of statins in subjects with any coronary syndrome eligible for elective, semi-urgent or primary percutaneous coronary intervention: ARMYDA-Original, NAPLES I-II, ARMYDA-ACS, ARMYDA-RECAPTURE, Non-STEMI-Korean, Korean-STEMI trials.

Influence of fluvastatin on cardiac function and baroreflex sensitivity in diabetic rats

AIM

To investigate whether fluvastatin is able to ameliorate the impaired cardiac function or baroreflex sensitivity (BRS) in rats with type 1 diabetes.

METHODS

Type 1 diabetic rats were induced by intraperitoneal injection of streptozotocin (STZ) and then administered fluvastatin (1.5, 3.0, and 6.0 mg·kg(-1)·d(-1)) for 30 d. Food and drink intake was recorded every day. Fasting blood glucose (FBG) level, blood lipid level, cardiac function and BRS were measured in diabetic rats after fluvastatin treatment for 30 d.

RESULTS

The polydipsia, polyphagia and abnormal biochemical indexes of blood were significantly ameliorated by the the 3.0- and 6.0-mg doses of fluvastatin in STZ-induced diabetic rats. FBG was decreased in diabetic rats after fluvastatin treatment for 30 d. The left ventricular systolic pressure (LVSP) and the maximum rate of change of left ventricular pressure in the isovolumic contraction and relaxation period (±dp/dt(max)) were elevated, and left ventricular diastolic pressure (LVEDP) was decreased by fluvastatin. The attenuated heart rate responses to arterial blood pressure (ABP) increase induced by phenylephrine (PE) and ABP decrease induced by sodium nitroprusside (SNP) were reversed by the 3.0-mg dose of fluvastatin.

CONCLUSION

Fluvastatin regulates blood lipid levels and decreases the FBG level in diabetic rats. These responses can protect the diabetic heart from complications by improving cardiac function and BRS.

Tumor-specific HMG-CoA reductase expression in primary premenopausal breast cancer predicts response to tamoxifen

Introduction

We previously reported an association between tumor-specific 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR) expression and a good prognosis in breast cancer. Here, the predictive value of HMG-CoAR expression in relation to tamoxifen response was examined.

Methods

HMG-CoAR protein and RNA expression was analyzed in a cell line model of tamoxifen resistance using western blotting and PCR. HMG-CoAR mRNA expression was examined in 155 tamoxifen-treated breast tumors obtained from a previously published gene expression study (Cohort I). HMG-CoAR protein expression was examined in 422 stage II premenopausal breast cancer patients, who had previously participated in a randomized control trial comparing 2 years of tamoxifen with no systemic adjuvant treatment (Cohort II). Kaplan-Meier analysis and Cox proportional hazards modeling were used to estimate the risk of recurrence-free survival (RFS) and the effect of HMG-CoAR expression on tamoxifen response.

Results

HMG-CoAR protein and RNA expression were decreased in tamoxifen-resistant MCF7-LCC9 cells compared with their tamoxifen-sensitive parental cell line. HMG-CoAR mRNA expression was decreased in tumors that recurred following tamoxifen treatment (P < 0.001) and was an independent predictor of RFS in Cohort I (hazard ratio = 0.63, P = 0.009). In Cohort II, adjuvant tamoxifen increased RFS in HMG-CoAR-positive tumors (P = 0.008). Multivariate Cox regression analysis demonstrated that HMG-CoAR was an independent predictor of improved RFS in Cohort II (hazard ratio = 0.67, P = 0.010), and subset analysis revealed that this was maintained in estrogen receptor (ER)-positive patients (hazard ratio = 0.65, P = 0.029). Multivariate interaction analysis demonstrated a difference in tamoxifen efficacy relative to HMG-CoAR expression (P = 0.05). Analysis of tamoxifen response revealed that patients with ER-positive/HMG-CoAR tumors had a significant response to tamoxifen (P = 0.010) as well as patients with ER-positive or HMG-CoAR-positive tumors (P = 0.035). Stratification according to ER and HMG-CoAR status demonstrated that ER-positive/HMG-CoAR-positive tumors had an improved RFS compared with ER-positive/HMG-CoAR-negative tumors in the treatment arm (P = 0.033); this effect was lost in the control arm (P = 0.138), however, suggesting that HMG-CoAR predicts tamoxifen response.

Conclusions

HMG-CoAR expression is a predictor of response to tamoxifen in both ER-positive and ER-negative disease. Premenopausal patients with tumors that express ER or HMG-CoAR respond to adjuvant tamoxifen.

Mevalonate cascade regulation of airway mesenchymal cell autophagy and apoptosis: a dual role for p53

Statins inhibit the proximal steps of cholesterol biosynthesis, and are linked to health benefits in various conditions, including cancer and lung disease. We have previously investigated apoptotic pathways triggered by statins in airway mesenchymal cells, and identified reduced prenylation of small GTPases as a primary effector mechanism leading to p53-mediated cell death. Here, we extend our studies of statin-induced cell death by assessing endpoints of both apoptosis and autophagy, and investigating their interplay and coincident regulation. Using primary cultured human airway smooth muscle (HASM) and human airway fibroblasts (HAF), autophagy, and autophagosome formation and flux were assessed by transmission electron microscopy, cytochemistry (lysosome number and co-localization with LC3) and immunoblotting (LC3 lipidation and Atg12-5 complex formation). Chemical inhibition of autophagy increased simvastatin-induced caspase activation and cell death. Similarly, Atg5 silencing with shRNA, thus preventing Atg5-12 complex formation, increased pro-apoptotic effects of simvastatin. Simvastatin concomitantly increased p53-dependent expression of p53 up-regulated modulator of apoptosis (PUMA), NOXA, and damage-regulated autophagy modulator (DRAM). Notably both mevalonate cascade inhibition-induced autophagy and apoptosis were p53 dependent: simvastatin increased nuclear p53 accumulation, and both cyclic pifithrin-α and p53 shRNAi partially inhibited NOXA, PUMA expression and caspase-3/7 cleavage (apoptosis) and DRAM expression, Atg5-12 complex formation, LC3 lipidation, and autophagosome formation (autophagy). Furthermore, the autophagy response is induced rapidly, significantly delaying apoptosis, suggesting the existence of a temporally coordinated p53 regulation network. These findings are relevant for the development of statin-based therapeutic approaches in obstructive airway disease.

Role of cholesterol in the development and progression of breast cancer

Diet and obesity are important risk factors for cancer development. Many studies have suggested an important role for several dietary nutrients in the progression and development of breast cancer. However, few studies have specifically addressed the role of components of a Western diet as important factors involved in breast cancer initiation and progression. The present study examined the role of cholesterol in the regulation of tumor progression in a mouse model of mammary tumor formation. The results suggest that cholesterol accelerates and enhances tumor formation. In addition, tumors were more aggressive, and tumor angiogenesis was enhanced. Metabolism of cholesterol was also examined in this mouse model. It was observed that plasma cholesterol levels were reduced during tumor development but not prior to its initiation. These data provide new evidence for an increased utilization of cholesterol by tumors and for its role in tumor formation. Taken together, these results imply that an increase in plasma cholesterol levels accelerates the development of tumors and exacerbates their aggressiveness.

Pitavastatin prevents postprandial endothelial dysfunction via reduction of the serum triglyceride level in obese male subjects

Obesity is a well-established risk factor for the development and progression of coronary heart disease. Moreover, endothelial dysfunction is an early event in atherosclerosis and is known to be associated with postprandial hypertriglyceridemia. The purpose of this study was to determine whether a statin might have an effect on postprandial hypertriglyceridemia, and thereby on endothelial function in obese subjects. Twenty-four obese male subjects were recruited for this study. They were randomly assigned to receive pitavastatin (2 mg/day) or placebo for 2 weeks. The oral fat loading test using OFTT cream was performed pre- and post-treatment, in which the lipid profile and flow-mediated dilation (FMD) were assessed before and 4 h after an oral fat load. In the oral fat loading test conducted pretreatment, the oral fat load induced a marked increase of the serum triglyceride (TG) level and decrease in FMD in the pitavastatin and placebo group. In the test conducted post-treatment, the increase in postprandial TG was attenuated (+183 vs. +81 mg/dL, P < 0.001) and decrease in postprandial FMD was completely abolished (-1.1 vs. +0.1%, P < 0.01) by pitavastatin treatment. Moreover, there was a good correlation between the change in postprandial TG and the change in postprandial FMD after the 2 weeks of treatment (r = -0.737, P < 0.001). Pitavastatin might prevent endothelial dysfunction caused by postprandial hypertriglyceridemia within 2 weeks of therapy in obese subjects.

Distribution of endogenous farnesyl pyrophosphate and four species of lysophosphatidic acid in rodent brain

Lysophosphatidic acid (LPA) is the umbrella term for lipid signaling molecules that share structural homology and activate the family of LPA receptors. Farnesyl Pyrophosphate (FPP) is commonly known as an intermediate in the synthesis of steroid hormones; however, its function as a signaling lipid is beginning to be explored. FPP was recently shown to an activator of the G-protein coupled receptor 92 (also known as LPA5) of the calcium channel TRPV₃. The LPA receptors (including GPR92) are associated with the signal transduction of noxious stimuli, however, very little is known about the distribution of their signaling ligands (LPAs and FPP) in the brain. Here, using HPLC/MS/MS, we developed extraction and analytical methods for measuring levels of FPP and 4 species of LPA (palmitoyl, stearoyl, oleoyl and arachidonoyl-sn-glycerol-3 phosphate) in rodent brain. Relative distributions of each of the five compounds was significantly different across the brain suggesting divergent functionality for each as signaling molecules based on where and how much of each is being produced. Brainstem, midbrain, and thalamus contained the highest levels measured for each compound, though none in the same ratios while relatively small amounts were produced in cortex and cerebellum. These data provide a framework for investigations into functional relationships of these lipid ligands in specific brain areas, many of which are associated with the perception of pain.

Roles of cholesterol and lipids in the etiopathogenesis of Alzheimer's disease

Alzheimer's disease is the principal cause of dementia throughout the world and the fourth cause of death in developed economies.This brain disorder is characterized by the formation of brain protein aggregates, namely, the paired helical filaments and senile plaques. Oxidative stress during life, neuroinflamamtion, and alterations in neuron-glia interaction patterns have been also involved in the etiopathogenesis of this disease. In recent years, cumulative evidence has been gained on the involvement of alteration in neuronal lipoproteins activity, as well as on the role of cholesterol and other lipids in the pathogenesis of this neurodegenerative disorder. In this review, we analyze the links between changes in cholesterol homeostasis, and the changes of lipids of major importance for neuronal activity and Alheimer's disease. The investigation on the fine molecular mechanisms underlying the lipids influence in the etiopathogenesis of Alzheimer's disease may shed light into its treatment and medical management.

Reduction of brain beta-amyloid (Abeta) by fluvastatin, a hydroxymethylglutaryl-CoA reductase inhibitor, through increase in degradation of amyloid precursor protein C-terminal fragments (APP-CTFs) and Abeta clearance

Epidemiological studies suggest that statins (hydroxymethylglutaryl-CoA reductase inhibitors) could reduce the risk of Alzheimer disease. Although one possible explanation is through an effect on beta-amyloid (Abeta) metabolism, its effect remains to be elucidated. Here, we explored the molecular mechanisms of how statins influence Abeta metabolism. Fluvastatin at clinical doses significantly reduced Abeta and amyloid precursor protein C-terminal fragment (APP-CTF) levels among APP metabolites in the brain of C57BL/6 mice. Chronic intracerebroventricular infusion of lysosomal inhibitors blocked these effects, indicating that up-regulation of the lysosomal degradation of endogenous APP-CTFs is involved in reduced Abeta production. Biochemical analysis suggested that this was mediated by enhanced trafficking of APP-CTFs from endosomes to lysosomes, associated with marked changes of Rab proteins, which regulate endosomal function. In primary neurons, fluvastatin enhanced the degradation of APP-CTFs through an isoprenoid-dependent mechanism. Because our previous study suggests additive effects of fluvastatin on Abeta metabolism, we examined Abeta clearance rates by using the brain efflux index method and found its increased rates at high Abeta levels from brain. As LRP1 in brain microvessels was increased, up-regulation of LRP1-mediated Abeta clearance at the blood-brain barrier might be involved. In cultured brain microvessel endothelial cells, fluvastatin increased LRP1 and the uptake of Abeta, which was blocked by LRP1 antagonists, through an isoprenoid-dependent mechanism. Overall, the present study demonstrated that fluvastatin reduced Abeta level by an isoprenoid-dependent mechanism. These results have important implications for the development of disease-modifying therapy for Alzheimer disease as well as understanding of Abeta metabolism.

The mevalonate cascade as a target to suppress extracellular matrix synthesis by human airway smooth muscle

Smooth muscle cells promote fibroproliferative airway remodeling in asthma, and transforming growth factor β1 (TGFβ1) is a key inductive signal. Statins are widely used to treat hyperlipidemia. Growing evidence indicates they also exert a positive impact on lung health, but the underlying mechanisms are unclear. We assessed the effects of 3-hydroxy-3-methlyglutaryl-coenzyme A (HMG-CoA) reductase inhibition with simvastatin on the fibrotic function of primary cultured human airway smooth muscle cells. Simvastatin blocked de novo cholesterol synthesis, but total myocyte cholesterol content was unaffected. Simvastatin also abrogated TGFβ1-induced collagen I and fibronectin expression, and prevented collagen I secretion. The depletion of mevalonate cascade intermediates downstream from HMG-CoA underpinned the effects of simvastatin, because co-incubation with mevalonate, geranylgeranylpyrophosphate, or farnesylpyrophosphate prevented the inhibition of matrix protein expression. We also showed that human airway myocytes express both geranylgeranyl transferase 1 (GGT1) and farnesyltransferase (FT), and the inhibition of GGT1 (GGTI inhibitor-286, 10 μM), but not FT (FTI inhibitor-277, 10 μM), mirrored the suppressive effects of simvastatin on collagen I and fibronectin expression and collagen I secretion. Moreover, simvastatin and GGTI-286 both prevented TGFβ1-induced membrane association of RhoA, a downstream target of GGT1. Our findings suggest that simvastatin and GGTI-286 inhibit synthesis and secretion of extracellular matrix proteins by human airway smooth muscle cells by suppressing GGT1-mediated posttranslational modification of signaling molecules such as RhoA. These findings reveal mechanisms related to evidence for the positive impact of statins on pulmonary health.

New pharmacological treatments for improving renal outcomes in diabetes

Diabetic nephropathy is the most common and most rapidly growing cause of end-stage renal failure in developed countries. Diabetic nephropathy results from complex interactions between genetic, metabolic and hemodynamic factors. Improvements in our understanding of the pathogenesis of fibrosis associated with diabetic kidney disease have led to the identification of several novel targets for the treatment of diabetic nephropathy. Albuminuria is a useful clinical marker of diabetic nephropathy, as it can be used to predict a decline in renal function. A reduction in albuminuria might not, however, be reflective of a protective effect of therapies focused on ameliorating renal fibrosis. Although new strategies for slowing down the progression of several types of renal disease have emerged, the challenge of arresting the relentless progression of diabetic nephropathy remains. In this Review, we discuss novel pharmacological approaches that aim to improve the renal outcomes of diabetic nephropathy, including the use of direct renin inhibitors and statins. We also discuss the promise of using antifibrotic agents to treat diabetic nephropathy. The need for novel biomarkers of diabetic nephropathy is also highlighted.

Tumour-specific HMG-CoAR is an independent predictor of recurrence free survival in epithelial ovarian cancer

Background

Our group previously reported that tumour-specific expression of the rate-limiting enzyme in the mevalonate pathway, 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR) is associated with more favourable tumour parameters and a good prognosis in breast cancer. In the present study, the prognostic value of HMG-CoAR expression was examined in tumours from a cohort of patients with primary epithelial ovarian cancer.

Methods

HMG-CoAR expression was assessed using immunohistochemistry (IHC) on tissue microarrays (TMA) consisting of 76 ovarian cancer cases, analysed using automated algorithms to develop a quantitative scoring model. Kaplan Meier analysis and Cox proportional hazards modelling were used to estimate the risk of recurrence free survival (RFS).

Results

Seventy-two tumours were suitable for analysis. Cytoplasmic HMG-CoAR expression was present in 65% (n = 46) of tumours. No relationship was seen between HMG-CoAR and age, histological subtype, grade, disease stage, estrogen receptor or Ki-67 status. Patients with tumours expressing HMG-CoAR had a significantly prolonged RFS (p = 0.012). Multivariate Cox regression analysis revealed that HMG-CoAR expression was an independent predictor of improved RFS (RR = 0.49, 95% CI (0.25-0.93); p = 0.03) when adjusted for established prognostic factors such as residual disease, tumour stage and grade.

Conclusion

HMG-CoAR expression is an independent predictor of prolonged RFS in primary ovarian cancer. As HMG-CoAR inhibitors, also known as statins, have demonstrated anti-neoplastic effects in vitro, further studies are required to evaluate HMG-CoAR expression as a surrogate marker of response to statin treatment, especially in conjunction with current chemotherapeutic regimens.

Effects of lovastatin on breast cancer cells: a proteo-metabonomic study

INTRODUCTION

Statins are cholesterol-lowering drugs with pleiotropic activities including inhibition of isoprenylation and reduction of signals driving cell proliferation and survival responses.

METHODS

In this study we evaluated the effects of lovastatin acid and lactone on breast cancer MDAMB231 and MDAMB468 cells using a combination of proteomic and metabonomic profiling techniques.

RESULTS

Lovastatin inhibited proliferation of breast cancer cell lines. MDAMB231 cells were more sensitive to its effects, and in most cases lovastatin acid showed more potency towards the manipulation of protein expression than lovastatin lactone. Increased expression of Rho inhibitor GDI-2 stabilized the non-active Ras homolog gene family member A (RhoA) leading to a decreased expression of its active, membrane-bound form. Its downstream targets cofilin, CDC42 and G3BP1 are members of the GTPase family affected by lovastatin. Our data indicated that lovastatin modulated the E2F1-pathway through the regulation of expression of prohibitin and retinoblastoma (Rb). This subsequently leads to changes of E2F-downstream targets minichromosome maintenance protein 7 (MCM7) and MutS homolog 2 (MSH2). Lovastatin also regulated the AKT-signaling pathway. Increased phosphatase and tensin homolog (PTEN) and decreased DJ-1 expression lead to a down-regulation of the active pAkt. Lovastatin's involvement in the AKT-signaling pathway was confirmed by an upregulation of its downstream target, tumor progressor NDRG1. Metabolic consequences to lovastatin exposure included suppression of glycolytic and Krebs cycle activity, and lipid biosynthesis.

CONCLUSIONS

The combination of proteomics and metabonomics enabled us to identify several key targets essential to the antitumor activity of lovastatin. Our results imply that lovastatin has the potential to reduce the growth of breast cancer cells.

Influence of co-existing atrial fibrillation on the efficacy of atorvastatin treatment in patients with dilated cardiomyopathy: a pilot study

INTRODUCTION

The aim of the study was to assess the influence of co-existing atrial fibrillation (AF) on inflammatory condition factors, left ventricular function, clinical course and the efficacy of statin treatment of congestive heart failure in the course of dilated cardiomyopathy (DCM).

MATERIAL AND METHODS

In a prospective, randomized, open-label study, 69 patients with DCM and left ventricular ejection fraction (LVEF) < or =40% were divided into two groups, with and without AF, who were treated according to the recommended standards. 68% of patients from the group with AF and 59% of patients from the group without AF were administered atorvastatin 40 mg daily for 8 weeks and 10 mg for next 4 months. Clinical examination with the assessment of body mass index (BMI) and waist size were followed by routine laboratory tests, measurement of concentration of tumor necrosis factor (TNF-alpha), interleukin-6 (IL-6), and IL-10 in blood plasma, N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration in blood serum, echocardiographic examination, and the assessment of exercise capacity in 6-minute walk test (6-MWT). After six months, morbidity rate and the number of heart failure hospitalizations were also observed.

RESULTS

In the whole population of patients, a significantly higher concentration of NT-proBNP was observed in the AF group (2669 +/- 2192 vs 1540 +/- 1067, p = 0.02). After statin treatment, in patients with DCM and co-existing AF, higher values of NT-proBNP and IL-6 were observed compared to non-AF patients (1530 +/- 1054 vs 1006 +/- 1195, p = 0.04 and (14.16 +/- 13.40 vs 6.74 +/- 5.45, p = 0.02, respectively).

CONCLUSION

In patients with DCM and co-existing AF, a weaker effect of atorvastatin concerning the reduction of IL-6 and NT-proBNP concentration was observed than in patients without atrial fibrillation.

Fluvastatin reduces proliferation and increases apoptosis in women with high grade breast cancer

The purpose of this study is to determine the biologic impact of short-term lipophilic statin exposure on in situ and invasive breast cancer through paired tissue, blood and imaging-based biomarkers. A perioperative window trial of fluvastatin was conducted in women with a diagnosis of DCIS or stage 1 breast cancer. Patients were randomized to high dose (80 mg/day) or low dose (20 mg/day) fluvastatin for 3-6 weeks before surgery. Tissue (diagnostic core biopsy/final surgical specimen), blood, and magnetic resonance images were obtained before/after treatment. The primary endpoint was Ki-67 (proliferation) reduction. Secondary endpoints were change in cleaved caspase-3 (CC3, apoptosis), MRI tumor volume, and serum C-reactive protein (CRP, inflammation). Planned subgroup analyses compared disease grade, statin dose, and estrogen receptor status. Forty of 45 patients who enrolled completed the protocol; 29 had paired Ki-67 primary endpoint data. Proliferation of high grade tumors decreased by a median of 7.2% (P = 0.008), which was statistically greater than the 0.3% decrease for low grade tumors. Paired data for CC3 showed tumor apoptosis increased in 38%, remained stable in 41%, and decreased in 21% of subjects. More high grade tumors had an increase in apoptosis (60 vs. 13%; P = 0.015). Serum CRP did not change, but cholesterol levels were significantly lower post statin exposure (P < 0.001). Fluvastatin showed measurable biologic changes by reducing tumor proliferation and increasing apoptotic activity in high-grade, stage 0/1 breast cancer. Effects were only evident in high grade tumors. These results support further evaluation of statins as chemoprevention for ER-negative high grade breast cancers.

Simvastatin enhances hippocampal long-term potentiation in C57BL/6 mice

Statins inhibit 3-hydroxy-3-methylglutaryl CoA reductase, the rate-limiting enzyme in the cholesterol biosynthetic pathway, and they are widely used to control plasma cholesterol levels and prevent cardiovascular disease. However, emerging evidence indicates that the beneficial effects of statins extend to the CNS. Statins have been shown to improve the outcome of stroke and traumatic brain injury, and statin use has been associated with a reduced prevalence of Alzheimer's disease (AD) and dementia. However, prospective studies with statins in AD have produced mixed results. Recently, we reported that simvastatin, a widely used statin in humans, enhances learning and memory in non-transgenic mice as well as in transgenic mice with AD-like pathology on a mixed genetic background. However, the cellular and molecular mechanisms underlying the beneficial effects of simvastatin on learning and memory remain elusive. The present study was undertaken to investigate the effect of acute simvastatin treatment on hippocampal long-term potentiation (LTP), a cellular model of learning and memory, in brain slices from C57BL/6 mice. Our results demonstrate that a prolonged in vitro simvastatin treatment for 2-4 h, but not a short-term 20-min exposure, significantly increases the magnitude of LTP at CA3-CA1 synapses without altering basal synaptic transmission or the paired-pulse facilitation ratio in hippocampal slices. Furthermore, we show that phosphorylation of Akt (protein kinase B) is increased significantly in the CA1 region following 2-hour treatment with simvastatin, and that inhibition of Akt phosphorylation suppresses the simvastatin-induced enhancement of LTP. These findings suggest activation of Akt as a molecular pathway for augmented hippocampal LTP by simvastatin treatment, and implicate enhancement of hippocampal LTP as a potential cellular mechanism underlying the beneficial effects of simvastatin on cognitive function.

Simvastatin inhibits airway hyperreactivity: implications for the mevalonate pathway and beyond

RATIONALE

Statin use has been linked to improved lung health in asthma and chronic obstructive pulmonary disease. We hypothesize that statins inhibit allergic airway inflammation and reduce airway hyperreactivity via a mevalonate-dependent mechanism.

OBJECTIVES

To determine whether simvastatin attenuates airway inflammation and improves lung physiology by mevalonate pathway inhibition.

METHODS

BALB/c mice were sensitized to ovalbumin over 4 weeks and exposed to 1% ovalbumin aerosol over 2 weeks. Simvastatin (40 mg/kg) or simvastatin plus mevalonate (20 mg/kg) was injected intraperitoneally before each ovalbumin exposure.

MEASUREMENTS AND MAIN RESULTS

Simvastatin reduced total lung lavage leukocytes, eosinophils, and macrophages (P < 0.05) in the ovalbumin-exposed mice. Cotreatment with mevalonate, in addition to simvastatin, reversed the antiinflammatory effects seen with simvastatin alone (P < 0.05). Lung lavage IL-4, IL-13, and tumor necrosis factor-alpha levels were all reduced by treatment with simvastatin (P < 0.05). Simvastatin treatment before methacholine bronchial challenge increased lung compliance and reduced airway hyperreactivity (P = 0.0001).

CONCLUSIONS

Simvastatin attenuates allergic airway inflammation, inhibits key helper T cell type 1 and 2 chemokines, and improves lung physiology in a mouse model of asthma. The mevalonate pathway appears to modulate allergic airway inflammation, while the beneficial effects of simvastatin on lung compliance and airway hyperreactivity may be independent of the mevalonate pathway. Simvastatin and similar agents that modulate the mevalonate pathway may prove to be treatments for inflammatory airway diseases, such as asthma.

Atorvastatin reduces plasma levels of chemokine (CXCL10) in patients with Crohn's disease

Background

In Crohn's disease high tissue expression and serum levels of chemokines and their receptors are known to correlate with disease activity. Because statins can reduce chemokine expression in patients with coronary diseases, we wanted to test whether this can be achieved in patients with Crohn's disease.

Methodology/Principal Findings

We investigated plasma levels of chemokines (CCL2, CCL4, CCL11, CCL13, CCL17, CCL22, CCL26, CXCL8, CXCL10) and endothelial cytokines (sP-selectin, sE-selectin, sICAM-3, thrombomodulin) in ten Crohn's disease patients before and after thirteen weeks' daily treatment with 80 mg atorvastatin. Of the 13 substances investigated, only CXCL10 was found to be significantly reduced (by 34%, p = 0.026) in all of the treated patients. Levels of CXCL10 correlated with C-reactive protein (r = 0.82, p<0.01).

Conclusions/Significance

CXCL10 is a ligand for the CXCR3 receptor, the activation of which results in the recruitment of T lymphocytes and the perpetuation of mucosal inflammation. Hence the reduction of plasma CXCL10 levels by atorvastatin may represent a candidate for an approach to the treatment of Crohns disease in the future.

Trial Registration

ClinicalTrials.gov NCT00454545

Statin-induced muscle damage and atrogin-1 induction is the result of a geranylgeranylation defect

Statins are widely used to treat hypercholesterolemia but can lead to a number of side effects in muscle, including rhabdomyolysis. Our recent findings implicated the induction of atrogin-1, a gene required for the development of muscle atrophy, in statin-induced muscle damage. Since statins inhibit many biochemical reactions besides cholesterol synthesis, we sought to define the statin-inhibited pathways responsible for atrogin-1 expression and muscle damage. We report here that lovastatin-induced atrogin-1 expression and muscle damage in cultured mouse myotubes and zebrafish can be prevented in the presence of geranylgeranol but not farnesol. Further, inhibitors of the transfer of geranylgeranyl isoprene units to protein targets cause statin muscle damage and atrogin-1 induction in cultured cells and in fish. These findings support the concept that dysfunction of small GTP-binding proteins lead to statin-induced muscle damage since these molecules require modification by geranylgeranyl moieties for their cellular localization and activity. Collectively, our animal and in vitro findings shed light on the molecular mechanism of statin-induced myopathy and suggest that atrogin-1 may be regulated by novel signaling pathways.

Statins decrease dendritic arborization in rat sympathetic neurons by blocking RhoA activation

Clinical and experimental evidence suggest that statins decrease sympathetic activity, but whether peripheral mechanisms involving direct actions on post-ganglionic sympathetic neurons contribute to this effect is not known. Because tonic activity of these neurons is directly correlated with the size of their dendritic arbor, we tested the hypothesis that statins decrease dendritic arborization in sympathetic neurons. Oral administration of atorvastatin (20 mg/kg/day for 7 days) significantly reduced dendritic arborization in vivo in sympathetic ganglia of adult male rats. In cultured sympathetic neurons, statins caused dendrite retraction and reversibly blocked bone morphogenetic protein-induced dendritic growth without altering cell survival or axonal growth. Supplementation with mevalonate or isoprenoids, but not cholesterol, attenuated the inhibitory effects of statins on dendritic growth, whereas specific inhibition of isoprenoid synthesis mimicked these statin effects. Statins blocked RhoA translocation to the membrane, an event that requires isoprenylation, and constitutively active RhoA reversed statin effects on dendrites. These observations that statins decrease dendritic arborization in sympathetic neurons by blocking RhoA activation suggest a novel mechanism by which statins decrease sympathetic activity and protect against cardiovascular and cerebrovascular disease.

Prevention of atherosclerosis in patients living with HIV

INVESTIGATIONAL PRODUCT: Rosuvastatin (Crestor; Astra Zeneca).

ACTIVE INGREDIENTS

Rosuvastatin (5 mg).

STUDY TITLE

Prevention of Atherosclerosis in Patients Living with HIV.

PHASE OF STUDY

Phase III.

AIMS

PRIMARY AIM: To assess whether rosuvastatin therapy could slow the progression of the carotid intima-media thickness (C-IMT; as measured by the change in the mean IMT of the near and far walls of the distal common carotid arteries) over 2 years in HIV-infected patients (HIV-IP).

SECONDARY AIMS

To assess whether rosuvastatin therapy could reduce highly sensitive C reactive protein (hs-CRP) inflammatory marker that is increased in HIV-IP.To assess the effect of rosuvastatin therapy on serum lipid levels (total cholesterol [TC], low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol and triglycerides [TG]) and apolipoproteins (APO A1, APO B and APO B/A1).To assess the safety of rosuvastatin in HIV-IP through the evaluation of clinical laboratory analyses (liver function tests and creatine kinase) and adverse events (AEs).

STUDY DESIGN

Two-year randomized, double-blind, placebo-controlled, parallel group study.

PLANNED SAMPLE SIZE

320 HIV-IP.

SUMMARY OF ELIGIBILITY CRITERIA

HIV-IP who are aged between 30 and 60 years, with a CD4 count. greater than 200 cells/mm(3). Patients must be stable on combination antiretroviral therapy (cART) for at least 12 months and have a 10-year CVD risk of less than 20% (using the Framingham risk score).

NUMBER OF STUDY CENTERS

One.

DURATION OF TREATMENT

Two years (5 mg rosuvastatin or placebo once daily).

DOSE AND ROUTE OF ADMINISTRATION

Oral rosuvastatin (5 mg) once daily. The incidence of cardiovascular disease (CVD) in HIV-IP is at least three times higher than in the general population and further increases each year with combination anti-retroviral therapy (cART). The carotid atherosclerosis progression rate is 10 times higher in HIV-IP than in uninfected individuals. The aim of this study is to assess whether therapy with 5 mg rosuvastatin could: 1) Slow the progression in the mean IMT of the distal common carotid arteries over two years in HIV-IP.2) Change the concentration in the inflammatory marker--hs-CRP, which is increased in HIV-IP.3) Change the concentrations of TC, LDL cholesterol, HDL cholesterol, TG, apolipoproteins (APO) B, APO A1 and APO B/A1.4) Be administered safely in the study population. Pharmacological intervention with rosuvastatin will be evaluated in a double-blind, placebo-controlled, randomized clinical trial in HIV-IP treated with cART not matching the published selection criteria for lipid-lowering therapy. For the first time, this study will investigate anti-inflammatory and anti-atherogenic effects of a pharmacological lipid-lowering agent in HIV-IP that may lead to the reduction of CVD.

Atherosclerosis and osteoporosis: age-dependent degenerative processes or related entities?

Osteoporosis and atherosclerosis, two multifactorial and degenerative entities, are major public health problems. These diseases accompany the aging process and share common risk factors. Furthermore, several common pathophysiological factors have been suggested. These include similar molecular pathways involving bone and vascular mineralization, estrogen deficiency, parathyroid hormone, homocysteine, lipid oxidation products, inflammatory process, as well as vitamin D and K. Moreover, the use of statins, biphosphonates, beta-blockers and experimental dual-purpose therapies based on the biological linkage of the above entities may simultaneously benefit bone loss and vascular disease. This review considers a potential link between osteoporosis and atherosclerosis beyond aging. These common factors may lead to appropriate treatment strategies.

Evidence for statin pleiotropy in humans: differential effects of statins and ezetimibe on rho-associated coiled-coil containing protein kinase activity, endothelial function, and inflammation

BACKGROUND

By inhibiting 3-hydroxy-3-methylglutaryl coenzyme A reductase, statins not only reduce cholesterol biosynthesis but also decrease the formation of isoprenoids, which are important for mediating signaling through the Rho-associated coiled-coil containing protein kinase (ROCK) pathway. Increased ROCK activity has been implicated in endothelial dysfunction and vascular inflammation. We hypothesize that ezetimibe, which inhibits intestinal cholesterol absorption, may not exert similar cholesterol-independent or pleiotropic effects of statins and, when used with a lower dose of statin, have less effect on ROCK activity than a higher dose of statin.

METHODS AND RESULTS

In a prospective, randomized, observer-blinded study, we treated 60 dyslipidemic subjects without cardiovascular disease with simvastatin 40 mg/d, simvastatin/ezetimibe 10/10 mg/d, or placebo tablets for 28 days (n=20 in each arm). We evaluated baseline demographics and lipid levels, ROCK activity, C-reactive protein, and flow-mediated dilation before and after treatment. Compared with the placebo group, both treatment regimens decreased low-density lipoprotein cholesterol by 38% and C-reactive protein by 38% to 40% after 28 days (P<0.01 for both compared with placebo). Although the low-density lipoprotein cholesterol and C-reactive protein reductions were comparable with either lipid-lowering regimen, only simvastatin 40 mg reduced ROCK activity and improved flow-mediated dilation (P<0.01 for both compared with baseline). Reduction in ROCK activity with simvastatin 40 mg remained significant even after controlling for changes in low-density lipoprotein cholesterol (P=0.01) and correlated with improvement in flow-mediated dilation (R(2)=-0.78, P<0.01). No correlation was found between changes in flow-mediated dilation and changes in low-density lipoprotein cholesterol or C-reactive protein.

CONCLUSIONS

These results indicate that high-dose statin monotherapy exerts greater effects on ROCK activity and endothelial function, but not on C-reactive protein, than low-dose statin plus ezetimibe. These findings provide additional evidence of statin benefits beyond cholesterol lowering.

Inactivation of rho GTPases by statins attenuates anthrax lethal toxin activity

Anthrax lethal factor (LF), secreted by Bacillus anthracis, interacts with protective antigen to form a bipartite toxin (lethal toxin [LT]) that exerts pleiotropic biological effects resulting in subversion of the innate immune response. Although the mitogen-activated protein kinase kinases (MKKs) are the major intracellular protein targets of LF, the pathology induced by LT is not well understood. The statin family of HMG-coenzyme A reductase inhibitors have potent anti-inflammatory effects independent of their cholesterol-lowering properties, which have been attributed to modulation of Rho family GTPase activity. The Rho GTPases regulate vesicular trafficking, cytoskeletal dynamics, and cell survival and proliferation. We hypothesized that disruption of Rho GTPase function by statins might alter LT action. We show here that statins delay LT-induced death and MKK cleavage in RAW macrophages and that statin-mediated effects on LT action are attributable to disruption of Rho GTPases. The Rho GTPase-inactivating toxin, toxin B, did not significantly affect LT binding or internalization, suggesting that the Rho GTPases regulate trafficking and/or localization of LT once internalized. The use of drugs capable of inhibiting Rho GTPase activity, such as statins, may provide a means to attenuate intoxication during B. anthracis infection.

Isoprenoid quantitation in human brain tissue: a validated HPLC-fluorescence detection method for endogenous farnesyl- (FPP) and geranylgeranylpyrophosphate (GGPP)

Farnesyl- and geranylgeranylpyrophosphate (FPP and GGPP) are isoprenoid intermediates in the mevalonate pathway. They play a crucial role in cell survival, growth and differentiation due to their attachment (isoprenylation) to small GTPases (Ras, Rho, etc.). Isoprenoid formation seems to be tightly regulated within the mevalonate pathway and its perturbation has been linked to certain diseases (e.g., cancer, Alzheimer's disease), but tissue levels are unknown. It is therefore of the utmost importance to quantify these isoprenoids in diseased tissue or in tissue after drug administration. The current work describes an isolation procedure utilizing a combination of Extrelut(R) liquid/liquid and reversed-phase solid-phase extraction (SPE) for homogenized human frontal cortex tissue. In addition, after a careful validation of an HPLC-fluorescence method, this assay allowed the determination of nanomolar concentrations of endogenous FPP and GGPP levels (4.5 and 10.6 ng/mg protein, respectively) in human brain tissue. The method is selective, precise (<15% RSD), accurate (<15% relative error) and sensitive over a linear range of 10-400 ng/mL for FPP and 50-1000 ng/mL for GGPP according to the current FDA criteria for bioanalytical method validation. Overall, this new method introduces the ability to simultaneously quantify FPP and GGPP in human brain tissue, and is potentially applicable to several other tissues and species.

Prognostic impact of tumour-specific HMG-CoA reductase expression in primary breast cancer

Introduction

We have previously reported that tumour-specific expression of the rate-limiting enzyme, 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR), in the mevalonate pathway is associated with more favourable tumour parameters in breast cancer. In the present study, we examined the prognostic value of HMG-CoAR expression in a large cohort of primary breast cancer patients with long-term follow up.

Methods

The expression of HMG-CoAR was assessed by immunohistochemistry on tissue microarrays with tumour specimens from 498 consecutive cases of breast cancer with a median follow-up of 128 months. Kaplan Meier analysis and Cox proportional hazards modelling were used to estimate the rate of recurrence-free survival (RFS) and breast cancer specific survival (BCSS).

Results

In line with our previous findings, tumour-specific HMG-CoAR expression was associated with low grade (p < 0.001), small size (p = 0.007), oestrogen receptor (ER) positive (p = 0.01), low Ki-67 (p = 0.02) tumours. Patients with tumours expressing HMG-CoAR had a significantly prolonged RFS, even when adjusted for established prognostic factors (relative risk [RR] = 0.60, 95% confidence interval [CI] 0.40 to 0.92; p = 0.02). In ER-negative tumours, however, there was a trend, that was not significantly significant, towards a shorter RFS in HMG-CoAR expressing tumours.

Conclusions

HMG-CoAR expression is an independent predictor of a prolonged RFS in primary breast cancer. This may, however, not be true for ER-negative tumours. Further studies are needed to shed light on the value of HMG-CoAR expression as a surrogate marker of response to statin treatment, especially with respect to hormone receptor status.

Spectrum of pleiotropic effects of statins in heart failure

The syndrome of heart failure is characterized by increased levels of circulating inflammatory mediators, which have been implicated in the pathogenesis of heart failure. Recently, a number of studies have suggested that statins may exert salutary effects in patients who have heart failure by virtue of their pleiotropic (non-lipid lowering) actions. This article focuses on the non-lipid lowering effects of statins, with an emphasis on the anti-inflammatory properties of these agents.

Biphasic regulation of HMG-CoA reductase expression and activity during wound healing and its functional role in the control of keratinocyte angiogenic and proliferative responses

In this study, we determined the regulation and potential function of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMGR) during skin repair in mice. Upon skin injury, healthy mice exhibited a biphasic increase in HMGR expression and activity with elevated levels at days 3 and 13 post-wounding. In situ hybridization revealed wound margin keratinocytes as a cellular source of HMGR expression. In vitro experiments using cultured HaCaT keratinocytes uncovered epidermal growth factor (EGF), transforming growth factor (TGF)-alpha, and insulin as potent co-inducers of HMGR activity and vascular endothelial growth factor (VEGF) in the cells. Insulin-, but not EGF-mediated VEGF protein expression was functionally connected to co-induced HMGR activity, as simvastatin restrictively interfered only with insulin-induced translation of VEGF mRNA by inhibition of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) phosphorylation. Functional ablation of insulin-induced sterol regulatory element-binding protein (SREBP)-2 by siRNA abolished HMGR expression and insulin-triggered VEGF protein release from keratinocytes. Simvastatin also blocked proliferation of cultured keratinocytes. The observed inhibitory effects of simvastatin on keratinocyte VEGF expression and proliferation could be reversed by mevalonate, the product of HMGR enzymatic activity. In accordance, simvastatin-mediated inhibition of HMGR activity in acutely regenerating tissue of wounded mice was paralleled by a marked loss of VEGF protein expression and disturbances of normal proliferation processes in wound margin keratinocytes during skin repair.

Pitavastatin may reduce risk of steroid-induced osteonecrosis in rabbits: a preliminary histological study

Several animal and human studies suggest pharmacological approaches may prevent steroid-induced osteonecrosis (ON). We asked whether the newly developed 3-hydroxymethyl-3-glutaryl-CoA (HMG-CoA) reductase inhibitor, pitavastatin, could prevent steroid-induced ON in rabbits. We injected 65 adult male Japanese white rabbits once with 20 mg/kg of methylprednisolone acetate into the right gluteus medius muscle. The rabbits were divided into two groups; one group of 35 rabbits received pitavastatins (PS), and the other group of 30 rabbits received no prophylaxis (CTR). Hematological examinations were performed just before the steroid injection (0 weeks) and at 1 and 2 weeks after steroid injection; both the femora and the humeri were histologically examined 2 weeks postinjection. The incidence of histologic changes consistent with early ON in the PS group (13 of 35; 37%) was lower in comparison to the CTR group (21 of 30; 70%). The size of the bone marrow fat cells in the PS group (56.6 +/- 10 microm) was smaller than those in the CTR group (60 +/- 4 microm). The data suggest pitavastatin has the potential to lower the incidence of steroid-induced ON in rabbits.