2-(4-(2-((1H-Benzodimidazol-2-yl)thio)ethyl)piperazin-1-yl)-N-(6-methyl-2,4-bis(methylthio)pyridin-3-yl)acetamide hydrochloride (K-604, 2) has been identified as an aqueous-soluble potent ...inhibitor of human acyl-coenzyme A:cholesterol O-acyltransferase (ACAT, also known as SOAT)-1 that exhibits 229-fold selectivity for human ACAT-1 over human ACAT-2. In our molecular design, the insertion of a piperazine unit in place of a 6-methylene chain in the linker between the head (pyridylacetamide) and tail (benzimidazole) moieties led to a marked enhancement of the aqueous solubility (up to 19 mg/mL at pH 1.2) and a significant improvement of the oral absorption (the C max of 2 was 1100-fold higher than that of 1 in fasted dogs) compared with those of the previously selected compound, 1. After ensuring the pharmacological effects and safety, we designated 2 as a clinical candidate, named K-604. Considering the therapeutic results of ACAT inhibitors in past clinical trials, we believe that K-604 will be useful for the treatment of incurable diseases involving ACAT-1 overexpression.
Aims/Introduction
Dipeptidyl peptidase‐4 inhibitors are used for treatment of patients with type 2 diabetes. In addition to glycemic control, these agents showed beneficial effects on lipid ...metabolism in clinical trials. However, the mechanism underlying the lipid‐lowering effect of dipeptidyl peptidase‐4 inhibitors remains unclear. Here, we investigated the lipid‐lowering efficacy of anagliptin in a hyperlipidemic animal model, and examined the mechanism of action.
Materials and Methods
Male low‐density lipoprotein receptor‐deficient mice were administered 0.3% anagliptin in their diet. Plasma lipid levels were assayed and lipoprotein profile was analyzed using high‐performance liquid chromatography. Hepatic gene expression was examined by deoxyribonucleic acid microarray and quantitative polymerase chain reaction analyses. Sterol regulatory element‐binding protein transactivation assay was carried out in vitro.
Results
Anagliptin treatment significantly decreased the plasma total cholesterol (14% reduction, P < 0.01) and triglyceride levels (27% reduction, P < 0.01). Both low‐density lipoprotein cholesterol and very low‐density lipoprotein cholesterol were also decreased significantly by anagliptin treatment. Sterol regulatory element‐binding protein‐2 messenger ribonucleic acid expression level was significantly decreased at night in anagliptin‐treated mice (15% reduction, P < 0.05). Anagliptin significantly suppressed sterol regulatory element‐binding protein activity in HepG2 cells (21% decrease, P < 0.001).
Conclusions
The results presented here showed that the dipeptidyl peptidase‐4 inhibitor, anagliptin, exhibited a lipid‐lowering effect in a hyperlipidemic animal model, and suggested that the downregulation of hepatic lipid synthesis was involved in the effect. Anagliptin might have beneficial effects on lipid metabolism in addition to a glucose‐lowering effect.
The results presented here indicated that the DPP‐4 inhibitor, anagliptin, exhibited a lipid‐lowering effect in LDLR‐deficient mice as a hyperlipidemic animal model, and suggested that the downregulation of hepatic lipid synthesis was involved in the effect.
Hepatic ATP-binding cassette transporter A1 (ABCA1) plays a key role in high-density lipoprotein (HDL) production by apolipoprotein A-I (ApoA-I) lipidation. 3-Hydroxy-3-methylglutaryl coenzyme A ...(HMG-CoA) reductase inhibitors, statins, increase ABCA1 mRNA levels in hepatoma cell lines, but their mechanism of action is not yet clear. We investigated how statins increase ABCA1 in rat hepatoma McARH7777 cells. Pitavastatin, atorvastatin, and simvastatin increased total ABCA1 mRNA levels, whereas pravastatin had no effect. Pitavastatin also increased ABCA1 protein. Hepatic ABCA1 expression in rats is regulated by both liver X receptor (LXR) and sterol regulatory element–binding protein (SREBP2) pathways. Pitavastatin repressed peripheral type ABCA1 mRNA levels and its LXR-driven promoter, but activated the liver-type SREBP-driven promoter, and eventually increased total ABCA1 mRNA expression. Furthermore, pitavastatin increased peroxisome proliferator–activated receptor α (PPARα) and its downstream gene expression. Knockdown of PPARα attenuated the increase in ABCA1 protein, indicating that pitavastatin increased ABCA1 protein via PPARα activation, although it repressed LXR activation. Furthermore, the degradation of ABCA1 protein was retarded in pitavastatin-treated cells. These data suggest that pitavastatin increases ABCA1 protein expression by dual mechanisms: SREBP2-mediated mRNA transcription and PPARα-mediated ABCA1 protein stabilization, but not by the PPAR–LXR–ABCA1 pathway.
Supplementary Figures: available only at http://dx.doi.org/10.1254/jphs.10241FP
Abstract Background Acyl-coenzyme A:cholesterol O -acyltransferase-1 (ACAT-1), a major ACAT isozyme in macrophages, plays an essential role in foam cell formation in atherosclerotic lesions. However, ...whether pharmacological inhibition of macrophage ACAT-1 causes exacerbation or suppression of atherosclerosis is controversial. Methods and results We developed and characterized a novel ACAT inhibitor, K-604. The IC50 values of K-604 for human ACAT-1 and ACAT-2 were 0.45 and 102.85 μmol/L, respectively, indicating that K-604 is 229-fold more selective for ACAT-1. Kinetic analysis indicated that the inhibition was competitive with respect to oleoyl-coenzyme A with a K i value of 0.378 μmol/L. Exposure of human monocyte-derived macrophages to K-604 inhibited cholesterol esterification with IC50 of 68.0 nmol/L. Furthermore, cholesterol efflux from THP-1 macrophages to HDL3 or apolipoprotein A-I was enhanced by K-604. Interestingly, administration of K-604 to F1B hamsters on a high-fat diet at a dose of ≥1 mg/kg suppressed fatty streak lesions without affecting plasma cholesterol levels. Conclusions K-604, a potent and selective inhibitor of ACAT-1, suppressed the development of atherosclerosis in an animal model without affecting plasma cholesterol levels, providing direct evidence that pharmacological inhibition of ACAT-1 in the arterial walls leads to suppression of atherosclerosis.
Abstract Acyl-coenzyme A:cholesterol O-acyltransferase-1 (ACAT-1) plays an essential role in macrophage foam cell formation and progression of atherosclerosis. We developed a potent and selective ...ACAT-1 inhibitor, K-604, and tested its effects in apoE-knockout mice. Administration of K-604 to 8-week-old apoE-knockout mice for 12 weeks at a dose of 60 mg/kg/day significantly reduced macrophage-positive area and increased collagen-positive area in atherosclerotic plaques in the aorta without affecting plasma cholesterol levels or lesion areas, indicating direct plaque-modulating effects of K-604 on vascular walls independent of plasma cholesterol levels. Pactimibe, a nonselective inhibitor of ACAT-1 and ACAT-2, reduced plasma cholesterol levels but did not affect macrophage- or collagen-positive areas. The size of macrophages and cholesteryl ester contents in the aorta were reduced by K-604. Exposure of cultured human aortic smooth muscle cells to K-604 resulted in increased procollagen type 1 contents in the culture supernatant and increased procollagen type 1 mRNA levels. Procollagen production was unaffected by pactimibe even at a concentration that inhibited cholesterol esterification to the basal level. Thus, the plaque-modulating effects of K-604 can be explained by stimulation of procollagen production independent of ACAT inhibition in addition to potent inhibition of macrophage ACAT-1.
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We describe our molecular design of aortic-selective acyl-coenzyme A:cholesterol O-acyltransferase (ACAT, also abbreviated as SOAT) inhibitors, their structure–activity relationships ...(SARs) and their pharmacokinetic (PK) and pharmacological profiles. The connection of two weak ligands—N-(2,6-diisopropylphenyl)acetamide (50% inhibitory concentration IC50 = 8.6 μM) and 2-(methylthio)benzodoxazole (IC50 = 31 μM)—via a linker comprising a 6 methylene group chains yielded a highly potent molecule, 9-(benzodoxazol-2-ylthio)-N-(2,6-diisopropylphenyl)nonanamide (3h) that exhibited high potency (IC50 = 0.004 μM) toward aortic ACAT. This head-to-tail design made it possible to markedly enhance the activity to 2150- to 7750-fold and to discriminate the isoform-selectivity based on the double-induced fit mechanism. At doses of 1 and 3 mg/kg, 3h significantly decreased the lipid-accumulation areas in the aortic arch to 74 and 69%, respectively without reducing the plasma total cholesterol level in high fat- and cholesterol-fed F1B hamsters. Here, we demonstrate the antiatherosclerotic effect of 3hin vivo via its direct action on aortic ACAT and its powerful modulator of cholesterol level. This molecule is a potential therapeutic agent for the treatment of diseases involving ACAT-1 overexpression.
The triglyceride-lowering effect of pitavastatin, a potent 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, was investigated in a rat model of postprandial lipemia. Plasma ...triglyceride levels started to increase 4 h after the fat load, reached the maximum at 6 h and then gradually decreased. A single dose of pitavastatin (1 mg/kg) significantly suppressed chylomicron-triglyceride secretion into the lymph by 40% and delayed the elevation of plasma triglyceride. Pitavastatin at 1 mg/kg decreased the 6-h plasma triglyceride levels by 53% and at 0.5 mg/kg decreased the 0–12 h area under the curve (AUC) of triglyceride levels by 56%. Atorvastatin also caused decreases, but to a lesser extent. Pitavastatin, and atorvastatin to a lesser extent, reduced the activity of the intestinal microsomal triglyceride transfer protein (MTP) at 6 h. These results suggested that a single dose of pitavastatin lowered postprandial triglyceride levels in rats by decreasing chylomicron-triglyceride secretion, probably through a reduction of intestinal MTP activity and triglyceride droplet formation in the endoplasmic reticulum.
Statins exert atheroprotective effects through the induction of specific transcriptional factors in multiple organs. In endothelial cells, statin-dependent atheroprotective gene up-regulation is ...mediated by Kruppel-like factor (KLF) family transcription factors. To dissect the mechanism of gene regulation, we sought to determine molecular targets by performing microarray analyses of human umbilical vein endothelial cells (HUVECs) treated with pitavastatin, and KLF4 was determined to be the most highly induced gene. In addition, it was revealed that the atheroprotective genes induced with pitavastatin, such as nitric oxide synthase 3 (NOS3) and thrombomodulin (THBD), were suppressed by KLF4 knockdown. Myocyte enhancer factor-2 (MEF2) family activation is reported to be involved in pitavastatin-dependent KLF4 induction. We focused on MEF2C among the MEF2 family members and identified a novel functional MEF2C binding site 148 kb upstream of the KLF4 gene by chromatin immunoprecipitation along with deep sequencing (ChIP-seq) followed by luciferase assay. By applying whole genome and quantitative chromatin conformation analysis {chromatin interaction analysis with paired end tag sequencing (ChIA-PET), and real time chromosome conformation capture (3C) assay}, we observed that the MEF2C-bound enhancer and transcription start site (TSS) of KLF4 came into closer spatial proximity by pitavastatin treatment. 3D-Fluorescence in situ hybridization (FISH) imaging supported the conformational change in individual cells. Taken together, dynamic chromatin conformation change was shown to mediate pitavastatin-responsive gene induction in endothelial cells.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
「Abstract」. Hepatic ATP-binding cassette transporter A1 (ABCA1) plays a key role in high-density lipoprotein (HDL) production by apolipoprotein A-I (ApoA-I) lipidation. 3-Hydroxy-3-methyl-glutaryl ...coenzyme A (HMG-CoA) reductase inhibitors, statins, increase ABCA1 mRNA levels in hepatoma cell lines, but their mechanism of action is not yet clear. We investigated how statins increase ABCA1 in rat hepatoma McARH7777 cells. Pitavastatin, atorvastatin, and simvastatin increased total ABCA1 mRNA levels, whereas pravastatin had no effect. Pitavastatin also increased ABCA1 protein. Hepatic ABCA1 expression in rats is regulated by both liver X receptor (LXR) and sterol regulatory element-binding protein (SREBP2) pathways. Pitavastatin repressed peripheral type ABCA1 mRNA levels and its LXR-driven promoter, but activated the liver-type SREBP-driven promoter, and eventually increased total ABCA1 mRNA expression. Furthermore, pitavastatin increased peroxisome proliferator-activated receptor α (PPARα) and its downstream gene expression. Knockdown of PPARα attenuated the increase in ABCA1 protein, indicating that pitavastatin increased ABCA1 protein via PPARα activation, although it repressed LXR activation. Furthermore, the degradation of ABCA1 protein was retarded in pitavastatin-treated cells. These data suggest that pitavastatin increases ABCA1 protein expression by dual mechanisms: SREBP2-mediated mRNA transcription and PPARα-mediated ABCA1 protein stabilization, but not by the PPAR-LXR-ABCA1 pathway. Supplementary Figures: available only at http://dx.doi.org/10.1254/jphs.10241FP
Superoxide dismutase ISOD), catalase, hydroxyl radical (OH) scavengers and singlet oxygen (1O2) quenchers suppress the light signal from a xanthine oxidase/acetaldehyde system. Xanthine oxidase ...inhibitor allopurinol also suppresses the light signal from the system. Dilazep HCl (10-5-10-3M) suppresses the chemiluminescence in a concentration dependent manner without affecting the xanthine oxidase activity. These results suggest that dilazep exhibits a radical scavenger-like action.
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