Statins impair glucose uptake in human cells

Some pleiotropic effects of statins on hepatocellular carcinoma cells: Comparative study on atorvastatin, rosuvastatin and simvastatin

PURPOSE

For many years, statins have been the most commonly used drugs in cholesterol-lowering therapy. In addition to these therapeutic effects, statins exhibit other, pleiotropic effects that can be beneficial, but also harmful to cells and tissues. The aim of this research was to determine and compare the pleiotropic effects of structurally different statins: atorvastatin, simvastatin and rosuvastatin at different concentrations on hepatocellular carcinoma (HepG2) cells.

MATERIALS AND METHODS

The MTT assay was used to determine the cytotoxic effects of statins. The influence of statins on the production of reactive oxygen species (ROS) was determined by measuring fluorescent response of 2,7-dichlorofluorescein diacetate (DCFH-DA). The effect of statins on glucose production and excretion was determined with glucose production assay.

RESULTS

The obtained results confirmed that all tested statins exhibit cytotoxic effects, increase the production of ROS as well as the production and excretion of glucose from HepG2 cells. It was observed that all the mentioned effects are more pronounced with lipophilic statins, atorvastatin and simvastatin compared to hydrophilic rosuvastatin.

CONCLUSION

The less pronounced pleiotropic effects of rosuvastatin on HepG2 cells are probably due to differences in structure and solubility compared to atorvastatin and simvastatin. Transporter-dependent and a slower influx of rosuvastatin into cells compared to the tested lipophilic statins probably lead to a weaker accumulation of rosuvastatin in HepG2 cells, which results in less pronounced pleiotropic effects compared to lipophilic atorvastatin and simvastatin.

TFEB inhibition induces melanoma shut-down by blocking the cell cycle and rewiring metabolism

Melanomas are characterised by accelerated cell proliferation and metabolic reprogramming resulting from the contemporary dysregulation of the MAPK pathway, glycolysis and the tricarboxylic acid (TCA) cycle. Here, we suggest that the oncogenic transcription factor EB (TFEB), a key regulator of lysosomal biogenesis and function, controls melanoma tumour growth through a transcriptional programme targeting ERK1/2 activity and glucose, glutamine and cholesterol metabolism. Mechanistically, TFEB binds and negatively regulates the promoter of DUSP-1, which dephosphorylates ERK1/2. In melanoma cells, TFEB silencing correlates with ERK1/2 dephosphorylation at the activation-related p-Thr185 and p-Tyr187 residues. The decreased ERK1/2 activity synergises with TFEB control of CDK4 expression, resulting in cell proliferation blockade. Simultaneously, TFEB rewires metabolism, influencing glycolysis, glucose and glutamine uptake, and cholesterol synthesis. In TFEB-silenced melanoma cells, cholesterol synthesis is impaired, and the uptake of glucose and glutamine is inhibited, leading to a reduction in glycolysis, glutaminolysis and oxidative phosphorylation. Moreover, the reduction in TFEB level induces reverses TCA cycle, leading to fatty acid production. A syngeneic BRAFV600E melanoma model recapitulated the in vitro study results, showing that TFEB silencing sustains the reduction in tumour growth, increase in DUSP-1 level and inhibition of ERK1/2 action, suggesting a pivotal role for TFEB in maintaining proliferative melanoma cell behaviour and the operational metabolic pathways necessary for meeting the high energy demands of melanoma cells.

Induced pluripotent stem cell-derived cells model brain microvascular endothelial cell glucose metabolism

Glucose transport from the blood into the brain is tightly regulated by brain microvascular endothelial cells (BMEC), which also use glucose as their primary energy source. To study how BMEC glucose transport contributes to cerebral glucose hypometabolism in diseases such as Alzheimer's disease, it is essential to understand how these cells metabolize glucose. Human primary BMEC (hpBMEC) can be used for BMEC metabolism studies; however, they have poor barrier function and may not recapitulate in vivo BMEC function. iPSC-derived BMEC-like cells (hiBMEC) are readily available and have good barrier function but may have an underlying epithelial signature. In this study, we examined differences between hpBMEC and hiBMEC glucose metabolism using a combination of dynamic metabolic measurements, metabolic mass spectrometry, RNA sequencing, and Western blots. hiBMEC had decreased glycolytic flux relative to hpBMEC, and the overall metabolomes and metabolic enzyme levels were different between the two cell types. However, hpBMEC and hiBMEC had similar glucose metabolism, including nearly identical glucose labeled fractions of glycolytic and TCA cycle metabolites. Treatment with astrocyte conditioned media and high glucose increased glycolysis in both hpBMEC and hiBMEC, though hpBMEC decreased glycolysis in response to fluvastatin while hiBMEC did not. Together, these results suggest that hiBMEC can be used to model cerebral vascular glucose metabolism, which expands their use beyond barrier models.

Macrophage acetyl-CoA carboxylase regulates acute inflammation through control of glucose and lipid metabolism

Acetyl-CoA carboxylase (ACC) regulates lipid synthesis; however, its role in inflammatory regulation in macrophages remains unclear. We generated mice that are deficient in both ACC isoforms in myeloid cells. ACC deficiency altered the lipidomic, transcriptomic, and bioenergetic profile of bone marrow-derived macrophages, resulting in a blunted response to proinflammatory stimulation. In response to lipopolysaccharide (LPS), ACC is required for the early metabolic switch to glycolysis and remodeling of the macrophage lipidome. ACC deficiency also resulted in impaired macrophage innate immune functions, including bacterial clearance. Myeloid-specific deletion or pharmacological inhibition of ACC in mice attenuated LPS-induced expression of proinflammatory cytokines interleukin-6 (IL-6) and IL-1β, while pharmacological inhibition of ACC increased susceptibility to bacterial peritonitis in wild-type mice. Together, we identify a critical role for ACC in metabolic regulation of the innate immune response in macrophages, and thus a clinically relevant, unexpected consequence of pharmacological ACC inhibition.

The impact of hypotestosteronemia on cardiometabolic effects of atorvastatin in men with hypercholesterolemia: a pilot study

BACKGROUND

Hypothyroidism, hyperprolactinemia, macroprolactinemia and low vitamin D status were found to impair pleiotropic effects of hypolipidemic agents. The aim of the current study was to investigate whether cardiometabolic effects of atorvastatin in men are determined by endogenous testosterone.

METHODS

We studied three groups of men matched for age, BMI, plasma lipids and blood pressure: 19 untreated subjects with low testosterone levels (group A), 19 normotestosteronemic men receiving testosterone preparations (group B) and 21 untreated men with testosterone levels within the reference range (group C). Because of coexistent hypercholesterolemia, all subjects were managed with atorvastatin (40 mg daily) for 6 months. Glucose homeostasis markers, plasma lipids, as well as circulating levels of testosterone, uric acid, high-sensitivity C-reactive protein (hsCRP), fibrinogen, homocysteine and 25-hydroxyvitamin D were determined at the beginning and at the end of the study.

RESULTS

At baseline, group A was more insulin-resistant and was characterized by higher levels of hsCRP, fibrinogen and homocysteine, and lower levels of 25-hydroxyvitamin D than the remaining groups of patients. Despite reducing total and low-density lipoprotein cholesterol and hsCRP levels in all treatment groups, this effect was stronger in groups B and C than in group A. In groups B and C, atorvastatin use was also associated with a decrease in uric acid, fibrinogen and homocysteine concentrations and with an increase in 25-hydroxyvitamin D levels. In group A, but not in the remaining groups, the drug decreased insulin sensitivity.

CONCLUSION

The obtained results suggest that untreated hypotestosteronemia may attenuate cardiometabolic effects of atorvastatin in men.

New onset diabetes mellitus and cardiovascular events in Korean patients with acute myocardial infarction receiving high-intensity statins

BACKGROUND

High-intensity statin therapy is typically used in patients with acute myocardial infarction (AMI) for secondary prevention. However, there have been consistent concerns regarding its association with diabetes mellitus. We investigated the effect of high-intensity atorvastatin and rosuvastatin on new-onset diabetes mellitus (NODM) and cardiovascular outcomes over a 3-year follow-up period.

METHODS

Data from the Korea Acute Myocardial Infarction Registry were collected from November 2011 to October 2015, and 13,104 patients with AMI were enrolled from major cardiovascular centers. Among them, 2221 patients without diabetes who had been administered with high-intensity atorvastatin (40-80 mg) and rosuvastatin (20 mg) were investigated. The atorvastatin and rosuvastatin groups were evaluated for the incidence of NODM and major adverse cardiac events (MACE) including death, myocardial infarction, and revascularization cases in the following 3 years.

RESULTS

Baseline characteristics were comparable between the two groups. Event-free survival rate of NODM was not significantly different between the atorvastatin and rosuvastatin groups (92.5% vs. 90.8%, respectively; Log-rank P-value = 0.550). The event-free survival rate of MACE was also not significantly different between atorvastatin and rosuvastatin groups (89.0% vs. 89.6%, respectively; Log rank P-value = 0.662). Multivariate Cox analysis revealed that statin type was not a prognostic factor in the development of NODM and MACE.

CONCLUSIONS

Administering high-intensity atorvastatin and rosuvastatin in patients with AMI produced comparable effects on NODM and clinical outcomes, suggesting their clinical equivalence in secondary prevention.

Simvastatin profoundly impairs energy metabolism in primary human muscle cells

OBJECTIVES

Simvastatin use is associated with muscular side effects, and increased risk for type 2 diabetes (T2D). In clinical use, simvastatin is administered in inactive lipophilic lactone-form, which is then converted to active acid-form in the body. Here, we have investigated if lactone- and acid-form simvastatin differentially affect glucose metabolism and mitochondrial respiration in primary human skeletal muscle cells.

METHODS

Muscle cells were exposed separately to lactone- and acid-form simvastatin for 48 h. After pre-exposure, glucose uptake and glycogen synthesis were measured using radioactive tracers; insulin signalling was detected with Western blotting; and glycolysis, mitochondrial oxygen consumption and ATP production were measured with Seahorse XFe96 analyzer.

RESULTS

Lactone-form simvastatin increased glucose uptake and glycogen synthesis, whereas acid-form simvastatin did not affect glucose uptake and decreased glycogen synthesis. Phosphorylation of insulin signalling targets Akt substrate 160 kDa (AS160) and glycogen synthase kinase 3β (GSK3β) was upregulated with lactone-, but not with acid-form simvastatin. Exposure to both forms of simvastatin led to a decrease in glycolysis and glycolytic capacity, as well as to a decrease in mitochondrial respiration and ATP production.

CONCLUSIONS

These data suggest that lactone- and acid-forms of simvastatin exhibit differential effects on non-oxidative glucose metabolism as lactone-form increases and acid-form impairs glucose storage into glycogen, suggesting impaired insulin sensitivity in response to acid-form simvastatin. Both forms profoundly impair oxidative glucose metabolism and energy production in human skeletal muscle cells. These effects may contribute to muscular side effects and risk for T2D observed with simvastatin use.

Safety and Efficacy of Pitavastatin in Patients With Impaired Fasting Glucose and Hyperlipidemia: A Randomized, Open-labeled, Multicentered, Phase IV Study

PURPOSE

Although the role of high-intensity lipid-lowering therapy in cardiovascular protection has broadened, concerns still exist about new-onset diabetes mellitus (NODM), especially in vulnerable patients. This study aimed to compare the effect of high-dose (4 mg/d) and usual dose (2 mg/d) pitavastatin on glucose metabolism in patients with hyperlipidemia and impaired fasting glucose (IFG).

METHODS

In this 12-month study, glucose tolerance and lipid-lowering efficacy of high-dose pitavastatin (4 mg [study group]) was compared with that of usual dose pitavastatin (2 mg [control group]) in patients with hyperlipidemia and IFG. The primary end point was the change of glycosylated hemoglobin (HbA_1c) after 24 weeks of treatment. The secondary end points were as follows: (1) NODM within 1 year after treatment, (2) change of lipid parameters, (3) changes of adiponectin, and (4) change of blood glucose and insulin levels.

FINDINGS

Of the total 417 patients screened, 313 patients with hypercholesterolemia and IFG were randomly assigned into groups. The mean (SD) change in HbA_1c was 0.06% (0.20%) in the study group and 0.03% (0.22%) in the control group (P = 0.27). Within 1 year, 27 patients (12.3%) developed NODM, including 12 (10.6%) of 113 patients in the study group and 15 (14.2%) of 106 in the control group (P = 0.43). The study group had a significantly higher reduction of total cholesterol and LDL-C levels and a higher increase in apolipoprotein A1/apolipoprotein B ratio (0.68 [0.40] vs 0.51 [0.35], P < 0.01).

IMPLICATIONS

The high-dose pitavastatin therapy did not aggravate glucose metabolism compared with the usual dose therapy. Moreover, it had a better effect on cholesterol-lowering and apolipoprotein distribution in the patients with hyperlipidemia and IFG.

VEGF-B signaling impairs endothelial glucose transcytosis by decreasing membrane cholesterol content

Regulation of endothelial nutrient transport is poorly understood. Vascular endothelial growth factor B (VEGF‐B) signaling in endothelial cells promotes uptake and transcytosis of fatty acids from the bloodstream to the underlying tissue, advancing pathological lipid accumulation and lipotoxicity in diabetic complications. Here, we demonstrate that VEGF‐B limits endothelial glucose transport independent of fatty acid uptake. Specifically, VEGF‐B signaling impairs recycling of low‐density lipoprotein receptor (LDLR) to the plasma membrane, leading to reduced cholesterol uptake and membrane cholesterol loading. Reduced cholesterol levels in the membrane leads to a decrease in glucose transporter 1 (GLUT1)‐dependent endothelial glucose uptake. Inhibiting VEGF‐B in vivo reconstitutes membrane cholesterol levels and restores glucose uptake, which is of particular relevance for conditions involving insulin resistance and diabetic complications. In summary, our study reveals a mechanism whereby VEGF‐B regulates endothelial nutrient uptake and highlights the impact of membrane cholesterol for regulation of endothelial glucose transport.

Association between the membrane transporter proteins and type 2 diabetes mellitus

Introduction: The prevalence rate of diabetes is increasing day by day and the current scenario of the available agents for its treatment has given rise to stimulation in the search for new therapeutic targets and agents. Therefore the present review will examine the role of membrane composition in the pathophysiology of Type 2 Diabetes and the possible therapeutic approaches for this.Areas covered: Glucose transporter proteins (GLUTs) are integral membrane proteins which are responsible for facilitated glucose transport over the plasma membrane into cells. Thus, this chapter is an attempt to interpret the co-relation between membrane transporter proteins and lipid molecules of cell membrane and their implications in type 2 diabetes mellitus. The relationship between the composition controlled flexibility of the membrane in the insertion of GLUTs into cell membrane as well as its fusion with the membrane is the focus of this chapter.Expert opinion: There is increasing data on the central role of phospholipid composition toward T2DM. Plasma membrane lipid composition plays a key role in maintaining the machinery for insulin-independent GLUT insertion into the membrane as well as insulin-dependent GLUT4 containing vesicles. As a therapeutic option, the designing of new chemical entities should be aimed to decrease saturated fatty acids of lipid bilayer phospholipids to target type 2 diabetes mellitus.

The Pleiotropic Effects of Statins in Endocrine Disorders

BACKGROUND

The 3-Hydroxy-3-MethylGlutaryl-CoA reductase inhibitors, better known as statins, are used extensively in the treatment of dyslipidemia and cardiovascular risk reduction. They have also demonstrated a variety of non-lipid lowering, or pleiotropic effects. Pertaining to the endocrine system the benefits of statins can extend to patients with the polycystic ovarian syndrome and thyroid disease. However, there is also increasing evidence that statin use can lead to deleterious effects in different organs, including worsening glycemia and the development of diabetes mellitus.

OBJECTIVE

The aim of this review is to describe the most relevant and updated evidence regarding the pleiotropic effects of statins in endocrine disorders.

METHODS

We did a systematic review of scientific articles published in PubMed regarding the effects of statins on the different aspects of the endocrine system up until June 5th of 2018.

RESULTS

We identified preliminarily 61 publications, of which 4 were excluded due to having abstract format only, and 5 were excluded for not containing pertinent information to the study.

CONCLUSION

Several aspects of the endocrine system have been shown to be influenced by the pleiotropic effects that statins exert, however, the benefits of statins on cardiovascular morbidity and mortality largely outweigh this deleterious effect, and statin therapy should continue to be recommended.

Chronic exposure to environmentally relevant levels of simvastatin disrupts zebrafish brain gene signaling involved in energy metabolism

Simvastatin (SIM), a hypocholesterolaemic drug belonging to the statins group, is a widely prescribed pharmaceutical for prevention of cardiovascular diseases. Several studies showed that lipophilic statins, as SIM, cross the blood-brain barrier and interfere with the energy metabolism of the central nervous system in humans and mammalian models. In fish and other aquatic organisms, the effects of SIM on the brain energy metabolism are unknown, particularly following exposure to low environmentally relevant concentrations. Therefore, the present study aimed at investigating the influence of SIM on gene signaling pathways involved in brain energy metabolism of adult zebrafish (Danio rerio) following chronic exposure (90 days) to environmentally relevant SIM concentrations ranging from 8 ng/L to 1000 ng/L. Real-time PCR was used to determine the transcript levels of several genes involved in different pathways of the brain energy metabolism (glut1b, gapdh, acadm, accα, fasn, idh3a, cox4i1, and cox5aa). The findings here reported integrated well with ecological and biochemical responses obtained in a parallel study. Data demonstrated that SIM modulates transcription of key genes involved in the mitochondrial electron transport chain, in glucose transport and metabolism, in fatty acid synthesis and β-oxidation. Further, SIM exposure led to a sex-dependent transcription profile for some of the studied genes. Overall, the present study demonstrated, for the first time, that SIM modulates gene regulation of key pathways involved in the energy metabolism in fish brain at environmentally relevant concentrations.

Simvastatin re-sensitizes hepatocellular carcinoma cells to sorafenib by inhibiting HIF-1α/PPAR-γ/PKM2-mediated glycolysis

BACKGROUND

Hepatocellular carcinoma (HCC) is a common primary malignant tumor which usually progresses to an advanced stage because of late diagnosis. Sorafenib (Sora) is a first line medicine for advanced stage HCC; however, it has been faced with enormous resistance. Simvastatin (Sim) is a cholesterol-lowering drug and has been reported to inhibit tumor growth. The present study aims to determine whether Sora and Sim co-treatment can improve Sora resistance in HCC.

METHODS

The HCC cell line LM3 and an established Sora-resistant LM3 cell line (LM3-SR) were used to study the relationship between Sora resistance and aerobic glycolysis. Cell proliferation, apoptosis and glycolysis levels were analyzed by western blotting, flow cytometry analysis and biomedical tests. A xenograft model was also used to examine the effect of Sim in vivo. Detailed mechanistic studies were also undertaken by the use of activators and inhibitors, and lentivirus transfections.

RESULTS

Our results demonstrated that the resistance to Sora was associated with enhanced aerobic glycolysis levels. Furthermore, LM3-SR cells were more sensitive to Sim than LM3 cells, suggesting that combined treatment with both Sora and Sim could enhance the sensitivity of LM3-SR cells to Sora. This finding may be due to the suppression of the HIF-1α/PPAR-γ/PKM2 axis.

CONCLUSIONS

Simvastatin can inhibit the HIF-1α/PPAR-γ/PKM2 axis, by suppressing PKM2-mediated glycolysis, resulting in decreased proliferation and increased apoptosis in HCC cells, and re-sensitizing HCC cells to Sora.

Simvastatin Evokes An Unpredicted Antagonism For Tamoxifen In MCF-7 Breast Cancer Cells

Purpose

Tamoxifen (TAM) is a non-steroidal antiestrogen drug, used in the prevention and treatment of all stages of hormone-responsive breast cancer. Simvastatin (SIM) is a lipid-lowering agent and has been shown to inhibit cancer cell growth. The study aimed to investigate the effect of the combination of TAM and SIM in the treatment of estrogen receptor positive (ER+) breast cancer cell line, MCF-7, and in mice-bearing Ehrlich solid tumors.

Methods

MCF-7 cells were treated with different concentrations of TAM or/and SIM for 72 hours and the effects of the combination treatment on cytotoxicity, oxidative stress markers, apoptosis, angiogenesis, and metastasis were investigated using different techniques. In addition, tumor volume, oxidative markers, and inflammatory markers of the combined therapy were explored in mice bearing solid EAC tumors.

Results

The results showed that treatment of MCF-7 cells with the combination of 10 µM TAM, and 2 µM SIM significantly inhibited the increase in oxidative stress markers, LDH, and NF-kB induced by TAM. In addition, there was a significant decrease in the total apoptotic ratio, caspase-3 activity, and glucose uptake, while there was a non-significant change in Bax/bcl-2 ratio compared to the TAM-treated group. Using the isobologram equation, the drug interaction was antagonistic with combination index, CI=1.18. On the other hand, the combination regimen decreased VEGF, and matrix metalloproteinases, MMP 2&9 compared to TAM-treated cells. Additionally, in vivo, the combination regimen resulted in a non-significant decrease in the tumor volume, decreased oxidative markers, and the protein expression of TNF-α, and NF-κB compared to the TAM treated group.

Conclusion

Although the combination regimen of TAM and SIM showed an antagonistic drug interaction in MCF-7 breast cancer, it displayed favorable antiangiogenic, anti-metastatic, and anti-inflammatory effects.

Statin Toxicity

There is now overwhelming evidence to support lowering LDL-c (low-density lipoprotein cholesterol) to reduce cardiovascular morbidity and mortality. Statins are a class of drugs frequently prescribed to lower cholesterol. However, in spite of their wide-spread use, discontinuation and nonadherence remains a major gap in both the primary and secondary prevention of atherosclerotic cardiovascular disease. The major reason for statin discontinuation is because of the development of statin-associated muscle symptoms, but a range of other statin-induced side effects also exist. Although the mechanisms behind these side effects have not been fully elucidated, there is an urgent need to identify those at increased risk of developing side effects as well as provide alternative treatment strategies. In this article, we review the mechanisms and clinical importance of statin toxicity and focus on the evaluation and management of statin-associated muscle symptoms.

Evaluation of tamoxifen and simvastatin as the combination therapy for the treatment of hormonal dependent breast cancer cells

Tamoxifen (TAM) is a nonsteroidal antiestrogen drug, used in the prevention and treatment of all stages of hormone-responsive breast cancer. Simvastatin (SIM), a lipid-lowering agent, has been shown to inhibit cancer cell growth. The study aimed at investigating the impact of using SIM with TAM in estrogen receptor-positive (ER+) breast cancer cell line, T47D, as well as in mice-bearing Ehrlich solid tumor. The cell line was treated with different concentrations of TAM or/and SIM for 72 h. The effects of treatment on cytotoxicity, oxidative stress markers, apoptosis, angiogenesis, and metastasis were investigated. Our results showed that the combination treatment decreased the oxidative stress markers, glucose uptake, VEGF, and MMP 2 &9 in the cell line compared to TAM- treated cells. Drug interaction of TAM and SIM was synergistic in T47D by increasing the apoptotic makers Bax/BCL-2 ratio and caspase 3 activity. Additionally, in vivo, the combination regimen resulted in a non-significant decrease in the tumor volume compared to TAM treated group. Moreover, the combined treatment decreased the protein expression of TNF-α, NF-kB compared to control. In conclusion, our results suggest that SIM may serve as a promising treatment with TAM for improving the efficacy against estrogen receptor-positive (ER+) breast cancer.

Association of statin therapy with incidence of type 2 diabetes among US Veterans

Aims

While some but not all trial data have suggested an elevated risk of type 2 diabetes with statin use, limited data are available on the relation of statin treatment with glycaemia and risk of type 2 diabetes among Veterans. We examined whether statin use was associated with a higher incidence of type 2 diabetes and secondarily, if statin use was associated with high plasma glucose.

Methods

Prospective analysis based on electronic health records of 3,390,799 US Veterans from 2000 to 2012. We used the Veteran Administration Corporate Data Warehouse to obtain information on random plasma glucose. Statin use was captured using the pharmacy database. type 2 diabetes was defined as having at least one inpatient diagnosis or at least two outpatient diagnoses of type 2 diabetes using International Classification of Disease version 9 codes 250.xx, or the use of hypoglycemic agents. We used multi-level derived propensity score and inverse probability weighting to address confounding by indication and Cox regression to estimate relative risk of type 2 diabetes.

Results

The mean age was 62±11.9 years; 93.3% were men and 82.7% were white. During a median follow-up of 3.0 years, 443,104 new cases of type 2 diabetes occurred. Compared to no statin use, multivariable adjusted hazard ratio (95% CI) for type 2 diabetes was 1.21 (1.19-1.24) for low statin potency, 1.22 (1.21-1.23) for medium statin potency, and 1.34 (1.32-1.36) for high statin potency (p linear trend <0.0001). In secondary analysis, statin use was not associated with higher plasma glucose.

Conclusions

Our data show a positive association between statin use and incidence of type 2 diabetes among US Veterans.

The effect of atorvastatin on cardiometabolic risk factors in women with non-classic congenital adrenal hyperplasia: A pilot study

BACKGROUND

Individuals with non-classic congenital adrenal hyperplasia (NC-CAH) often show evidence of hyperandrogenism, including premature pubarche, accelerated linear growth velocity, short final height, hirsutism, acne, alopecia, impaired ovulation, menstrual dysfunction and subfertility. Although statins were found to reduce elevated levels of androgens in subjects with this disorder, no previous study has investigated whether 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors affect cardiometabolic risk factors in patients with NC-CAH.

METHODS

We studied 12 women with NC-CAH, 6 of whom because of coexisting hypercholesterolemia received atorvastatin (20-40 mg daily). Circulating levels of lipids, glucose homeostasis markers, plasma levels of androgens, 17-hydroxyprogesterone, high-sensitivity C-reactive protein (hsCRP), uric acid, fibrinogen, homocysteine and 25-hydroxyvitamin D, as well as urinary albumin-to-creatinine ratio (UACR) were determined at the beginning of the study and 12 weeks later.

RESULTS

Beyond affecting plasma lipids, atorvastatin reduced circulating levels of testosterone, dehydroepiandrosterone sulphate, androstenedione and 17-hydroxyprogesterone, and decreased free androgen index. Moreover, atorvastatin caused a decrease in plasma levels/urinary loss of uric acid, hsCRP, homocysteine and UACR, and insignificantly increased circulating levels of 25-hydroxyvitamin D. The drug produced no effect on plasma fibrinogen. The effect of atorvastatin on hsCRP, uric acid, homocysteine, 25-hydroxyvitamin D and UACR correlated with the magnitude of reduction in 17-hydroxyprogesterone and androgens.

CONCLUSION

Our results suggest that statin therapy reduces cardiometabolic risk in women with NC-CAH.

Effect of statins on fasting glucose in non-diabetic individuals: nationwide population-based health examination in Korea

BACKGROUND

Increasing evidence suggest that statin therapy has a diabetogenic effect. Individual types of statin may have a different effect on glucose metabolism. Using the repeated nationwide population-based health screening data in Korea, we investigated the longitudinal changes in fasting glucose level of non-diabetic individuals by use of statins.

METHODS

From the National Health Screening Cohort, we included 379,865 non-diabetic individuals who had ≥ 2 health screening examinations with fasting blood glucose level measured in 2002-2013. Using the prescription records of statins in the database, we calculated the proportion of days covered (PDC) and average number of defined daily doses per day (anDDD) by statins. We constructed multivariate linear mixed models to evaluate the effects of statins on the changes in fasting glucose (Δglu).

RESULTS

High PDC by statins had a significant positive effect on Δglu (coefficient for PDC 0.093 mmol/L, standard error 0.007, p < 0.001). anDDD by statins was also positively associated with Δglu (coefficient for anDDD 0.119 mmol/L, standard error 0.009, p < 0.001). Unlike statins, the PDC by fibrate and ezetimibe were not significantly associated with Δglu. There was no significant interaction effect on Δglu between time interval and statin. Considering individual types of statins, use of atorvastatin, rosuvastatin, pitavastatin, and simvastatin were significantly associated with increase of Δglu. Pravastatin, lovastatin, and fluvastatin were also positively associated with Δglu, but were not statistically significant.

CONCLUSIONS

More adherent and intensive use of statins was significantly associated with an increase in fasting glucose of non-diabetic individuals. In subgroup analysis of individual statins, use of atorvastatin, rosuvastatin, pitavastatin and simvastatin had significant association with increase in fasting glucose. Pravastatin, lovastatin, and fluvastatin had non-significant trend toward an increased fasting glucose. Our findings suggest the medication class effect of statins inducing hyperglycemia.

Lipid-Protein Interactions Are Unique Fingerprints for Membrane Proteins

Cell membranes contain hundreds of different proteins and lipids in an asymmetric arrangement. Our current understanding of the detailed organization of cell membranes remains rather elusive, because of the challenge to study fluctuating nanoscale assemblies of lipids and proteins with the required spatiotemporal resolution. Here, we use molecular dynamics simulations to characterize the lipid environment of 10 different membrane proteins. To provide a realistic lipid environment, the proteins are embedded in a model plasma membrane, where more than 60 lipid species are represented, asymmetrically distributed between the leaflets. The simulations detail how each protein modulates its local lipid environment in a unique way, through enrichment or depletion of specific lipid components, resulting in thickness and curvature gradients. Our results provide a molecular glimpse of the complexity of lipid-protein interactions, with potentially far-reaching implications for our understanding of the overall organization of real cell membranes.

Atorvastatin impaired glucose metabolism in C2C12 cells partly via inhibiting cholesterol-dependent glucose transporter 4 translocation

Skeletal muscle accounts for approximately 75% of glucose disposal in body and statins impair glucose metabolism. We aimed to investigate the effect of atorvastatin on glucose metabolism in C2C12 cells. Glucose metabolism and expression of glucose transporter 4 (GLUT4) and hexokinase II (HXKII) were measured following incubation with atorvastatin or pravastatin. Roles of cholesterol in atorvastatin-induced glucose metabolism impairment were investigated via adding cholesterol or mevalonic acid and confirmed by cholesterol depletion with methyl-β-cyclodextrin. Hypercholesterolemia mice induced by high fat diet (HFD) feeding, orally received atorvastatin (6 and 12 mg/kg) or pravastatin (12 mg/kg) for 22 days. Results showed that atorvastatin not pravastatin concentration-dependently impaired glucose consumption, glucose uptake and GLUT4 membrane translocation in C2C12 cells without affecting expression of HXKII or total GLUT4 protein. The atorvastatin-induced alterations were reversed by cholesterol or mevalonic acid. Cholesterol depletion exerted similar impact to atorvastatin, which could be alleviated by cholesterol supplement. Glucose consumption or GLUT4 translocation was positively associated with cellular cholesterol levels. In HFD mice, atorvastatin not pravastatin significantly increased blood glucose levels following glucose or insulin dose and decreased expression of membrane not total GLUT4 protein in muscle. Glucose exposure following glucose or insulin dose was negatively correlated to muscular free cholesterol concentration. Expression of membrane GLUT4 protein was positively related to free cholesterol in muscle. In conclusion, atorvastatin impaired glucose utilization in muscle cells partly via inhibiting GLUT4 membrane translocation due to inhibition of cholesterol synthesis by atorvastatin, at least, partly contributing to glucose intolerance in HFD mice.

Drugs Involved in Dyslipidemia and Obesity Treatment: Focus on Adipose Tissue

Metabolic syndrome can be defined as a state of disturbed metabolic homeostasis characterized by visceral obesity, atherogenic dyslipidemia, arterial hypertension, and insulin resistance. The growing prevalence of metabolic syndrome will certainly contribute to the burden of cardiovascular disease. Obesity and dyslipidemia are main features of metabolic syndrome, and both can present with adipose tissue dysfunction, involved in the pathogenic mechanisms underlying this syndrome. We revised the effects, and underlying mechanisms, of the current approved drugs for dyslipidemia and obesity (fibrates, statins, niacin, resins, ezetimibe, and orlistat; sibutramine; and diethylpropion, phentermine/topiramate, bupropion and naltrexone, and liraglutide) on adipose tissue. Specifically, we explored how these drugs can modulate the complex pathways involved in metabolism, inflammation, atherogenesis, insulin sensitivity, and adipogenesis. The clinical outcomes of adipose tissue modulation by these drugs, as well as differences of major importance for clinical practice between drugs of the same class, were identified. Whether solutions to these issues will be found in further adjustments and combinations between drugs already in use or necessarily in new advances in pharmacology is not known. To better understand the effect of drugs used in dyslipidemia and obesity on adipose tissue not only is challenging for physicians but could also be the next step to tackle cardiovascular disease.

Balancing Primary Prevention and Statin-Induced Diabetes Mellitus Prevention

Diabetes mellitus (DM), a modern-day epidemic, is a significant risk factor for cardiovascular disease. It is believed that statins elevate the risk of incident DM. Multiple trials were suggestive of the hyperglycemic effect of long-term statin use. This has prompted the Food and Drug Administration to include the risk of DM in the product label of statins. New-onset DM with statin use is biologically plausible and can be explained based on the multiple pathways in glucose metabolism affected by statins. Most pivotal clinical trials on statins were not powered to adequately assess the risk of incident DM with statin use, and the results from multiple meta-analyses are mixed. Currently, the US Preventive Services Task Force recommend the use of statins for primary prevention in patients with at least 1 cardiovascular risk factor and a 10-year risk of >7.5%. With the new American College of Cardiology/American Heart Association guidelines, the number of patients eligible for statin therapy has increased exponentially, which also calls for caution and increased vigilance in prescribing physicians regarding the controversies surrounding statin use. This article aims to highlight the existing data on statin use for primary prevention in diabetics and nondiabetics and the association of statins use with new-onset DM and its postulated mechanisms.

Zebrafish larva as a reliable model for in vivo assessment of membrane remodeling involvement in the hepatotoxicity of chemical agents

The easy-to-use in vivo model, zebrafish larva, is being increasingly used to screen chemical-induced hepatotoxicity, with a good predictivity for various mechanisms of liver injury. However, nothing is known about its applicability in exploring the mechanism called membrane remodeling, depicted as changes in membrane fluidity or lipid raft properties. The aim of this study was, therefore, to substantiate the zebrafish larva as a suitable in vivo model in this context. Ethanol was chosen as a prototype toxicant because it is largely described, both in hepatocyte cultures and in rodents, as capable of inducing a membrane remodeling leading to hepatocyte death and liver injury. The zebrafish larva model was demonstrated to be fully relevant as membrane remodeling was maintained even after a 1-week exposure without any adaptation as usually reported in rodents and hepatocyte cultures. It was also proven to exhibit a high sensitivity as it discriminated various levels of cytotoxicity depending on the extent of changes in membrane remodeling. In this context, its sensitivity appeared higher than that of WIF-B9 hepatic cells, which is suited for analyzing this kind of hepatotoxicity. Finally, the protection afforded by a membrane stabilizer, ursodeoxycholic acid (UDCA), or by a lipid raft disrupter, pravastatin, definitely validated zebrafish larva as a reliable model to quickly assess membrane remodeling involvement in chemical-induced hepatotoxicity. In conclusion, this model, compatible with a high throughput screening, might be adapted to seek hepatotoxicants via membrane remodeling, and also drugs targeting membrane features to propose new preventive or therapeutic strategies in chemical-induced liver diseases. Copyright © 2016 John Wiley & Sons, Ltd.

Statin-associated myopathy and the quest for biomarkers: can we effectively predict statin-associated muscle symptoms?

Over the past three decades, statins have become the cornerstone of prevention and treatment of atherosclerotic cardiovascular and metabolic diseases. Albeit generally well tolerated, these drugs can elicit a variety of muscle-associated symptoms that represent the most important reason for treatment discontinuation. Statin-associated myopathy has been systematically underestimated by randomized controlled trials as compared with the incidence observed in clinical practice and obtained from patient registries. There are several reasons for this discrepancy, among which the lack of reliable diagnostic tests and a validated questionnaire to assess muscle symptoms are recognized as unmet needs. Here, we review the cellular and molecular mechanisms underlying statin-associated myopathy and discuss the experimental and clinical data on various biomarkers to diagnose and predict muscle-related complaints.

Mammalian Glucose Transporter Activity Is Dependent upon Anionic and Conical Phospholipids

The regulated movement of glucose across mammalian cell membranes is mediated by facilitative glucose transporters (GLUTs) embedded in lipid bilayers. Despite the known importance of phospholipids in regulating protein structure and activity, the lipid-induced effects on the GLUTs remain poorly understood. We systematically examined the effects of physiologically relevant phospholipids on glucose transport in liposomes containing purified GLUT4 and GLUT3. The anionic phospholipids, phosphatidic acid, phosphatidylserine, phosphatidylglycerol, and phosphatidylinositol, were found to be essential for transporter function by activating it and stabilizing its structure. Conical lipids, phosphatidylethanolamine and diacylglycerol, enhanced transporter activity up to 3-fold in the presence of anionic phospholipids but did not stabilize protein structure. Kinetic analyses revealed that both lipids increase the k_cat of transport without changing the K_m values. These results allowed us to elucidate the activation of GLUT by plasma membrane phospholipids and to extend the field of membrane protein-lipid interactions to the family of structurally and functionally related human solute carriers.

Statin use in prediabetic patients: rationale and results to date

Prediabetes increases the risk for new-onset diabetes mellitus in patients receiving statins and this risk is dose- and time- dependent. Explanations for the conversion of a predisposed individual to diabetes are ambiguous including reductions in ubiquinone and adiponectin levels. However, the risk of new-onset diabetes mellitus is far outweighed by the statin-induced considerable decrease in cardiovascular events. Thus, prediabetic patients at high cardiovascular risk should not be denied high-dose statin therapy due to the small increase in the risk of developing diabetes since statins, especially at higher doses, cause greater reductions in cardiovascular events compared with standard statin doses. Moreover, lifestyle modification or even antidiabetic drugs are highly recommended in these individuals.

[Statins diabetogenicity: are all the same? state of art]

Statins are the cornerstone of cardiovascular prevention for general population, and in patients with type 2 diabetes mellitus (T2DM). However, statin therapy predisposes to type 2 diabetes, particularly in patients with predisposition to this condition. Some statins have been associated with increases in blood glucose in patients with or without DM2, and others have shown to have neutral effects, varying from one another their glucose or diabetogenic capacity. In many statin trials the incidence of DM2 has not been systematically evaluated and others the power to detect differences between statins is lacking. Evidence highest quality available comes from the meta-analysis of controlled clinical trials. The only controlled clinical trial to evaluate the incidence of new-onset T2DM is the J-PREDICT conducted with pitavastatin in patients with abnormal glucose tolerance. Preliminary results of this study show that pitavastatin is associated with a significant decrease in the incidence of de novo T2DM compared to only modification lifestyle. Therefore, pitavastatin may be an appropriate therapeutic alternative of choice to reduce vascular risk in patients with T2DM or at risk of presenting it.