Role of interleukin 6 signaling pathway in the anti-inflammatory effects of statins on coronary artery disease: Evidence from Mendelian randomization analysis

BACKGROUND

Statins are currently widely used in the prevention of coronary artery disease (CAD) primarily for lipid-lowering with a potential anti-inflammatory effect. However, it is not clear if their potential anti-inflammatory effects are mediated through the interleukin 6 (IL-6) signaling pathway.

METHODS

Using the Mendelian randomization (MR) approach followed by multivariable MR analyses, we examined the extent to which the effects of statins on CAD might be mediated through the IL-6 signaling pathway.

RESULTS

Our observations showed that HMG-CoA reductase, using LDL levels as a proxy, had a significant effect on upstream IL-6 (βMR = 0.47, P-IVW = 0.01) and nominally significant effects on IL-6RA (βMR = 0.22, P-IVW = 0.047) and APOB (βMR = 0.82, P-IVW = 1.8 × 10-33). While the IL-6 signaling cascade (IL-6RA βMR = -0.06, P-IVW = 3.45 × 10-20 and IL-6 βMR = -0.03, P-IVW = 0.09) and the anti-inflammatory effect of HMG-CoA reductase (βMR = -0.31, P-IVW = 0.01) was found to influence the risk of CAD, the multivariable MR (MVMR) model indicated that the anti-inflammatory effect of HMG-CoA reductase is not likely to be mediated through the IL-6 signaling cascade, including APOB and IL-6RA (MVMRβ = 0.23, P = 0.688).

CONCLUSIONS

Our findings suggest that statins may use inflammatory mechanisms independent of the IL-6 signaling pathway to prevent CAD. This result could potentially affect the definition of the target population for statin use.

Relationships of brain cholesterol and cholesterol biosynthetic enzymes to Alzheimer's pathology and dementia in the CFAS population-derived neuropathology cohort

Altered cholesterol metabolism is implicated in brain ageing and Alzheimer's disease. We examined whether key genes regulating cholesterol metabolism and levels of brain cholesterol are altered in dementia and Alzheimer's disease neuropathological change (ADNC). Temporal cortex (n = 99) was obtained from the Cognitive Function and Ageing Study. Expression of the cholesterol biosynthesis rate-limiting enzyme HMG-CoA reductase (HMGCR) and its regulator, SREBP2, were detected using immunohistochemistry. Expression of HMGCR, SREBP2, CYP46A1 and ABCA1 were quantified by qPCR in samples enriched for astrocyte and neuronal RNA following laser-capture microdissection. Total cortical cholesterol was measured using the Amplex Red assay. HMGCR and SREBP2 proteins were predominantly expressed in pyramidal neurones, and in glia. Neuronal HMGCR did not vary with ADNC, oxidative stress, neuroinflammation or dementia status. Expression of HMGCR neuronal mRNA decreased with ADNC (p = 0.022) and increased with neuronal DNA damage (p = 0.049), whilst SREBP2 increased with ADNC (p = 0.005). High or moderate tertiles for cholesterol levels were associated with increased dementia risk (OR 1.44, 1.58). APOE ε4 allele was not associated with cortical cholesterol levels. ADNC is associated with gene expression changes that may impair cholesterol biosynthesis in neurones but not astrocytes, whilst levels of cortical cholesterol show a weak relationship to dementia status.

Statins-From Fungi to Pharmacy

Statins have been used in the treatment of hyperlipidemia, both as monotherapy and in combination therapy. Natural fermentation processes of fungi such as Monascus spp., Penicillium spp., Aspergillus terreus, and Pleurotus ostreatus have given rise to natural statins. Compactin (mevastatin), the original naturally occurring statin, is the primary biotransformation substrate in the manufacturing process of marketed drugs. Statins are classified into natural, semi-synthetic derivatives of natural statins, and synthetic ones. Synthetic statins differ from natural statins in their structural composition, with the only common feature being the HMG-CoA-like moiety responsible for suppressing HMG-CoA reductase. Statins do not differ significantly regarding their pleiotropic and adverse effects, but their characteristics depend on their pharmacokinetic parameters and chemical properties. This paper focuses on describing the processes of obtaining natural statins, detailing the pharmacokinetics of available statins, divided into natural and synthetic, and indicating their pleiotropic effects.

Association of HMGCR inhibition with rheumatoid arthritis: a Mendelian randomization and colocalization study

Objective

The objective of this study was to investigate the association between hydroxymethylglutaryl coenzyme A reductase (HMGCR) inhibition and rheumatoid arthritis (RA) using drug-target Mendelian randomization (MR) and genetic colocalization analyses.

Methods

Two sets of genetic instruments were employed to proxy HMGCR inhibitors: expression quantitative trait loci (eQTLs) of target genes from the eQTLGen Consortium and genetic variants associated with low-density lipoprotein cholesterol (LDL-C) levels with HMGCR locus from open genome-wide association studies (GWAS). Positive control analyses were conducted on type 2 diabetes and coronary heart disease, and multiple sensitivity analyses were performed.

Results

Genetically proxied expression of eQTL was associated with a lower risk of RA (OR=0.996, 95% CI =0.992-0.999, p= 0.032). Similarly, hydroxymethylglutaryl coenzyme A reductase (HMGCR)-mediated low-density lipoprotein cholesterol was negatively associated with risk of RA (OR=0.995, 95% CI =0.991-0.998, p= 0.007) in the inverse variance weighted (IVW) method. Colocalization analysis suggested a 74.6% posterior probability of sharing a causal variant within the SNPs locus (PH4 = 74.6%). A causal relationship also existed between HMGCR-mediated LDL and RA risk factors. The results were also confirmed by multiple sensitivity analyses. The results in positive control were consistent with the previous study.

Conclusion

Our study suggested that HMGCR inhibition was associated with an increased risk of RA while also highlighting an increased risk of current smoking and obesity. These findings contribute to a growing body of evidence regarding the adverse effects of HMGCR inhibition on RA risk, calling for further research on alternative approaches using HMGCR inhibitors in RA management.

CaaX-motif-adjacent residues influence G protein gamma (Gγ) prenylation under suboptimal conditions

Prenylation is an irreversible post-translational modification that supports membrane interactions of proteins involved in various cellular processes, including migration, proliferation, and survival. Dysregulation of prenylation contributes to multiple disorders, including cancers and vascular and neurodegenerative diseases. Prenyltransferases tether isoprenoid lipids to proteins via a thioether linkage during prenylation. Pharmacological inhibition of the lipid synthesis pathway by statins is a therapeutic approach to control hyperlipidemia. Building on our previous finding that statins inhibit membrane association of G protein γ (Gγ) in a subtype-dependent manner, we investigated the molecular reasoning for this differential inhibition. We examined the prenylation of carboxy-terminus (Ct) mutated Gγ in cells exposed to Fluvastatin and prenyl transferase inhibitors and monitored the subcellular localization of fluorescently tagged Gγ subunits and their mutants using live-cell confocal imaging. Reversible optogenetic unmasking-masking of Ct residues was used to probe their contribution to prenylation and membrane interactions of the prenylated proteins. Our findings suggest that specific Ct residues regulate membrane interactions of the Gγ polypeptide, statin sensitivity, and extent of prenylation. Our results also show a few hydrophobic and charged residues at the Ct are crucial determinants of a protein's prenylation ability, especially under suboptimal conditions. Given the cell and tissue-specific expression of different Gγ subtypes, our findings indicate a plausible mechanism allowing for statins to differentially perturb heterotrimeric G protein signaling in cells depending on their Gγ-subtype composition. Our results may also provide molecular reasoning for repurposing statins as Ras oncogene inhibitors and the failure of using prenyltransferase inhibitors in cancer treatment.

Unveiling the Cardioprotective Power: Liquid Chromatography-Mass Spectrometry (LC-MS)-Analyzed Neolamarckia cadamba (Roxb.) Bosser Leaf Ethanolic Extract against Myocardial Infarction in Rats and In Silico Support Analysis

Neolamarckia cadamba (Roxb.) Bosser, a member of the Rubiaceae family, is a botanical species with recognized therapeutic properties. It is commonly used in traditional medicine to treat cardiac ailments and other disorders. However, the precise active constituents and the potential mechanisms by which they manage cardiovascular disorders remain unclear. Therefore, this study aimed to ascertain the bioactive components and investigate their underlying mechanisms of action. N. cadamba is used to treat cardiovascular disorders using the integrated metabolomic methodology. An HPLC-QTOF-MS/MS analysis determined the potential chemicals in the N. cadamba leaf ethanol extract (NCEE). A thorough investigation of the NCEE samples used in this study led to the identification of 32 phytoconstituents. Of the 32 compounds, 19 obeyed Lipinski's rule of five (RO5). A molecular docking study directed towards HMG-CoA reductase used 19 molecules. The reference drug atorvastatin indicated a binding energy of -3.9 kcal/mol, while the other substances, Cinchonain Ib and Dukunolide B, revealed binding energies of -5.7 and -5.3 kcal/mol, respectively. Both phytocompounds showed no toxicity and exhibited favorable pharmacokinetic properties. In vivo study results concluded that treatment with NCEE significantly reduced the cardiac myocardial infarction (MI) marker CK-MB and atherogenic risk indices, such as the atherogenic index plasma (AIP), cardiac risk ratio (CRR), and atherogenic coefficient (AC) in isoproterenol-induced MI rats. In MI rats, NCEE therapy significantly improved the antioxidant system of the heart tissue, as evidenced by the increased levels of GSH and SOD, lower levels of the oxidative stress marker MDA, and significantly decreased HMG-CoA activity. Additionally, electrocardiogram (ECG) signals from rats treated with NCEE resembled those treated with traditional atorvastatin to treat myocardial infarction. This study used H&E staining to show that administering NCEE before treatment reduced cardiac myocyte degeneration in rats with myocardial infarction, increased the presence of intact nuclei, and increased myocardial fiber strength. The potential cardioprotective effect observed in myocardial infarction (MI) rats treated with NCEE can be extrapolated from computational data to be caused by Cinchonain Ib.

Lactobacillus reuteri NCIMB 30242 (LRC) Inhibits Cholesterol Synthesis and Stimulates Cholesterol Excretion in Animal and Cell Models

In this study, we evaluated the effects of Lactobacillus reuteri NCIMB (LRC™) supplementation on hypercholesterolemia by researching its effects on cellular cholesterol metabolism in hypercholesterolemic rats (KHGASP-22-170) and HepG2 cell line. Rats were separated into six groups after adaptation and were then fed a normal control (NC), a high-cholesterol diet (HC), or a HC supplemented with simvastatin 15 mg/kg body weight (positive control [PC]), LRC 1 × 109 colony-forming units (CFU)/rat/day, LRC 4 × 109 CFU/rat/day, or LRC 1 × 1010 CFU/rat/day (1 × 109, 4 × 109, or 1 × 1010). The rats were dissected to study the effects of LRC on cholesterol metabolism and intestinal excretion at the end of experimental period. We discovered that LRC mainly participated in the restraint of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, the uptake of low-density lipoprotein (LDL) cholesterol into tissues, partially in the transport of cholesteryl esters into high density lipoprotein for maturation, and intestinal excretion of cholesterol. These results are supported by the expression of transcription factors and enzymes such as HMG-CoA reductase, SREBP2, CYP7A1, CETP, and LCAT in both messenger RNA (mRNA) and protein levels in serum and hepatic tissue. Furthermore, the LRC treatment in HepG2 significantly reduced the mRNA expression of HMG-CoA reductase, SREBP2, and CEPT and significantly increased the mRNA expression of LDL-receptor, LCAT, and CYP7A1 at all doses. Hence, we suggest that LRC supplementation could alleviate the serum cholesterol level by inhibiting the intracellular cholesterol synthesis, and augmenting excretion of intestinal cholesterol.

Onosma hispidum L. extract reverses hyperlipidemia, hypertension, and associated vascular dysfunction in rats

Onosma hispidum.L (O. hispidum) belongs to the family Boregineacea. A preliminary study and its medicinal use suggested its role in the management of hyperlipidemia. The present study aimed to assess the effect of methanolic root extract of O. hispidum in hyperlipidemia and associated vascular dysfunction. Oral administration of O. hispidum crude extract (Oh. Cr) to tyloxopol and high fat diet-induced hyperlipidemic Sprague-Dawley rats for 10 and 28 days significantly reduced total triglycerides and cholesterol (p < 0.001), compared to hyperlipidemic rats. Oh. Cr 250 mg/kg orally treated rats significantly (p < 0.001) reduced both the total body weight and atherogenic index in tylaxopol and HFD rats. In HMG-CoA assay, the inhibition of the enzyme was significant in Oh.Cr (250 mg/kg) treated group. Histopathological studies indicated that the group treated with Oh.Cr 250 mg/kg/day showed regular morphology of aortic intima, media and adventitia, and improved the endothelial damage. To investigate the vascular dysfunction, isolated rat aorta rings from all groups were pre-contracted with 1 µM phenylephrine (PE), and the effect of acetylcholine (Ach) was monitored. In the aorta isolated from Oh.Cr (50 mg/kg) treated group, Ach completely relaxed the PE-induced contraction with EC₅₀ value of 0.05 µg/mL 0.015 (0.01-0.2) compared to the hyperlipidemic control group (<30% relaxation). In atorvastatin (10 mg/kg) treated rat aorta, Ach showed 50% relaxation. The Oh.Cr extract also reduced (105.92 ± 1.14 to 66.63 ± 0.85 mmHg) mean arterial pressure in hyperlipidemic hypertensive rats. These findings suggest that extract of O. hispidum is an effective remedy for hypercholesterolemia, and hypertriglyceridemia, which acts through inhibition of HMG-CoA and improving vascular dysfunction.

Statin Persistence and Adherence among Older Initiators: A Nationwide Cohort Study Using the National Health Insurance Claims Database in Japan

PURPOSE

This study clarifies the reality of persistence and adherence to statins in older Japanese people who initiated statin use and compares it between primary and secondary prevention cohorts.

METHODS

The nationwide study using the national claims database targeted statin initiators aged ≥55 years from FY2014 to FY2017 in Japan. Persistence and adherence to statins were analyzed overall and according to subgroups based on sex, age stratum, and prevention cohorts. Permissible gap of median days that statins were supplied per prescription to an individual was employed. Persistence rates were estimated as Kaplan-Meier estimates. Poor adherence during persistence was evaluated and defined as <0.8 of the proportion of days covered (PDC).

RESULTS

Of 3,675,949 initiators, approximately 80% initiated statin use with strong variants. The persistence rate at 1 year was 0.61. Poor adherence to statins during persistence was 8.0% in all patients and this value gradually improved with increasing age. Persistence rate and adherence were lower for the primary prevention cohort than for the secondary prevention cohort, and a notable sex difference was observed for the secondary prevention cohort, which was lower in females but was almost never and slightly observed in the primary prevention cohorts without and with high-risk factors, respectively.

CONCLUSIONS

Many statin initiators discontinued statins shortly following statin initiation but adherence while on statin therapy was good. Attentively watching older patients not to discontinue statins and listening to their reasons for discontinuation are required, especially for initiators in primary prevention and females in secondary prevention.

Computer-aided, resistance gene-guided genome mining for proteasome and HMG-CoA reductase inhibitors

Secondary metabolites (SMs) are biologically active small molecules, many of which are medically valuable. Fungal genomes contain vast numbers of SM biosynthetic gene clusters (BGCs) with unknown products, suggesting that huge numbers of valuable SMs remain to be discovered. It is challenging, however, to identify SM BGCs, among the millions present in fungi, that produce useful compounds. One solution is resistance gene-guided genome mining, which takes advantage of the fact that some BGCs contain a gene encoding a resistant version of the protein targeted by the compound produced by the BGC. The bioinformatic signature of such BGCs is that they contain an allele of an essential gene with no SM biosynthetic function, and there is a second allele elsewhere in the genome. We have developed a computer-assisted approach to resistance gene-guided genome mining that allows users to query large databases for BGCs that putatively make compounds that have targets of therapeutic interest. Working with the MycoCosm genome database, we have applied this approach to look for SM BGCs that target the proteasome β6 subunit, the target of the proteasome inhibitor fellutamide B, or HMG-CoA reductase, the target of cholesterol reducing therapeutics such as lovastatin. Our approach proved effective, finding known fellutamide and lovastatin BGCs as well as fellutamide- and lovastatin-related BGCs with variations in the SM genes that suggest they may produce structural variants of fellutamides and lovastatin. Gratifyingly, we also found BGCs that are not closely related to lovastatin BGCs but putatively produce novel HMG-CoA reductase inhibitors.

ONE-SENTENCE SUMMARY

A new computer-assisted approach to resistance gene-directed genome mining is reported along with its use to identify fungal biosynthetic gene clusters that putatively produce proteasome and HMG-CoA reductase inhibitors.

Fine-tuning of nitrogen-containing bisphosphonate esters that potently induce degradation of HMG-CoA reductase

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase is the rate-limiting enzyme in the cholesterol biosynthetic pathway, and competitive inhibitors targeting the catalytic domain of this enzyme, so-called statins, are widely used for the treatment of hyperlipidemia. The membrane domain mediates the sterol-accelerated degradation, a post-translational negative feedback mechanism, and small molecules triggering such degradation have been studied as an alternative therapeutic option. Such strategies are expected to provide benefits over catalytic site inhibitors, as the inhibition leads to transcriptional and post-translational upregulation of the enzyme, necessitating a higher dose of the inhibitors and concomitantly increasing the risk of serious adverse effects, including myopathies. Through our previous study on SR12813, a synthetic small molecule that induces degradation of HMG-CoA reductase, we identified a nitrogen-containing bisphosphonate ester SRP3042 as a highly potent HMG-CoA reductase degrader. Here, we performed a systematic structure-activity relationship study to optimize its activity and physicochemical properties, specifically focusing on the reduction of lipophilicity. Mono-fluorination of tert-butyl groups on the molecules was found to increase the HMG-CoA reductase degradation activity while reducing lipophilicity, suggesting the mono-fluorination of saturated alkyl groups as a useful strategy to balance potency and lipophilicity of the lead compounds.

Atorvastatin's Reduction of Alzheimer's Disease and Possible Alteration of Cognitive Function in Midlife as well as its Treatment

Over the past 20 years, advances in the field of pathogenesis have inspired researchers to look into novel pharmacological therapeutics that are more focused on the pathophysiological events of the disease (AD). This review article discussed the prior use of statins for the prevention of Alzheimer's disease, which can help prevent the disease. Other drugs, such as memantine and donepezil, are available, but they cannot prevent the onset of AD in middle age. Based on available clinical data, the valuable effects of statins are mediated by alteration of β-amyloid (Aβ) and tau metabolism, genetic and lifestyle risk factors, along with other clinical aspects of AD. These findings suggested that using statins in middle age may help to prevent Alzheimer's disease by modifying genetic and non-genetic risk factors in later stages of life. In the present review, we elaborated upon the modification of risk factors and amyloid metabolism in the development and progression of AD and their modulation through atorvastatin. Future directions in the research and treatment of Alzheimer's disease patients include the use of antisense oligonucleotides (ASO) to change target expression, and researchers discovered decreased markers of oxidative stress in tissues affected by tau pathology in response to RNA interference treatment.

Statin-associated muscle symptoms: Myth or reality?

Statin-associated muscle symptoms is an entity that encompasses a constellation of various clinical manifestations of variyng severity. Since the introduction of the first statins, numerous studies have been published regarding its incidence, pathophysiology, diagnosis and treatment; however, to this day these aspects are still controversial. With the progressive increase in the use of statins in the general population, notifications of adverse reactions related to its use have multiplied, particularly those related to muscular toxicity. Nevertheless, the differences between the published studies, both in methodology and in the results obtained, make this relationship a complex issue of great interest for clinicians and patients. The integration of the evidence that we currently have can help us understand better this entity and facilitate its management in clinical practice.

Viral Hepatitis, Cholesterol Metabolism, and Cholesterol-Lowering Natural Compounds

Hepatitis is defined as inflammation of the liver; it can be acute or chronic. In chronic cases, the prolonged inflammation gradually damages the liver, resulting in liver fibrosis, cirrhosis, and sometimes liver failure or cancer. Hepatitis is often caused by viral infections. The most common causes of viral hepatitis are the five hepatitis viruses—hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), and hepatitis E virus (HEV). While HAV and HEV rarely (or do not) cause chronic hepatitis, a considerable proportion of acute hepatitis cases caused by HBV (sometimes co-infected with HDV) and HCV infections become chronic. Thus, many medical researchers have focused on the treatment of HBV and HCV. It has been documented that host lipid metabolism, particularly cholesterol metabolism, is required for the hepatitis viral infection and life cycle. Thus, manipulating host cholesterol metabolism-related genes and proteins is a strategy used in fighting the viral infections. Efforts have been made to evaluate the efficacy of cholesterol-lowering drugs, particularly 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, in the treatment of hepatitis viral infections; promising results have been obtained. This review provides information on the relationships between hepatitis viruses and host cholesterol metabolism/homeostasis, as well as the discovery/development of cholesterol-lowering natural phytochemicals that could potentially be applied in the treatment of viral hepatitis.

Associations of genetically proxied inhibition of HMG-CoA reductase, NPC1L1, and PCSK9 with breast cancer and prostate cancer

BACKGROUND

Preclinical and epidemiological studies indicate a potential chemopreventive role of low-density lipoprotein cholesterol (LDL-C) -lowering drugs in the risks of breast cancer and prostate cancer, but the causality remains unclear. We aimed to evaluate the association of genetically proxied inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, Niemann-Pick C1-Like 1 (NPC1L1), and proprotein convertase subtilisin/kexin type 9 (PCSK9) with risks of breast cancer and prostate cancer using a two-sample Mendelian randomization (MR) method.

METHODS

Single-nucleotide polymorphisms (SNPs) in HMGCR, NPC1L1, and PCSK9 associated with LDL-C in a genome-wide association study (GWAS) meta-analysis from the Global Lipids Genetics Consortium (GLGC; up to 188,577 European individuals) were used to proxy inhibition of HMG-CoA reductase, NPC1L1, and PCSK9. Summary statistics with outcomes were obtained from a GWAS meta-analysis of the Breast Cancer Association Consortium (BCAC; 228,951 European females) and a Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome (PRACTICAL; 140,254 European males) consortium. SNPs were combined into multiallelic models and MR estimates representing lifelong inhibition of targets were generated using the inverse-variance weighted method.

RESULTS

Genetically proxied inhibition of HMG-CoA reductase (OR: 0.84; 95% CI 0.74-0.95; P = 0.005) and NPC1L1 (OR: 0.72; 95% CI 0.58-0.90; P = 0.005) equivalent to a 1-mmol/L (38.7 mg/dL) reduction in LDL-C was associated with reduced breast cancer risk. There were no significant associations of genetically proxied inhibition of PCSK9 with breast cancer. In contrast, genetically proxied inhibition of PCSK9 (OR: 0.81; 95% CI 0.73-0.90; P < 0.001) but not HMG-CoA reductase and NPC1L1 was negatively associated with prostate cancer. In the secondary analysis, genetically proxied inhibition of HMG-CoA reductase (OR: 0.82; 95% CI 0.71-0.95; P = 0.008) and NPC1L1 (OR: 0.66; 95% CI 0.50-0.86; P = 0.002) was associated with estrogen receptor-positive breast cancer, whereas there was no association of HMG-CoA reductase and NPC1L1 with estrogen receptor-negative breast cancer.

CONCLUSIONS

Genetically proxied inhibition of HMG-CoA reductase and NPC1L1 was significantly associated with lower odds of breast cancer, while genetically proxied inhibition of PCSK9 was associated with reduced risk of prostate cancer. Further randomized controlled trials are needed to confirm the respective roles of these LDL-C-lowering drugs in breast cancer and prostate cancer.

Lipoproteins and cancer: The role of HDL-C, LDL-C, and cholesterol-lowering drugs

Cholesterol is an amphipathic sterol molecule that is vital for maintaining normal physiological homeostasis. It is a relatively complicated molecule with 27 carbons whose synthesis starts with 2-carbon units. This in itself signifies the importance of this molecule. Cholesterol serves as a precursor for vitamin D, bile acids, and hormones, including estrogens, androgens, progestogens, and corticosteroids. Although essential, high cholesterol levels are associated with cardiovascular and kidney diseases and cancer initiation, progression, and metastasis. Although there are some contrary reports, current literature suggests a positive association between serum cholesterol levels and the risk and extent of cancer development. In this review, we first present a brief overview of cholesterol biosynthesis and its transport, then elucidate the role of cholesterol in the progression of some cancers. Suggested mechanisms for cholesterol-mediated cancer progression are plentiful and include the activation of oncogenic signaling pathways and the induction of oxidative stress, among others. The specific roles of the lipoprotein molecules, high-density lipoprotein (HDL) and low-density lipoprotein (LDL), in this pathogenesis, are also reviewed. Finally, we hone on the potential role of some cholesterol-lowering medications in cancer.

Statins and Bempedoic Acid: Different Actions of Cholesterol Inhibitors on Macrophage Activation

Statins represent the most prescribed class of drugs for the treatment of hypercholesterolemia. Effects that go beyond lipid-lowering actions have been suggested to contribute to their beneficial pharmacological properties. Whether and how statins act on macrophages has been a matter of debate. In the present study, we aimed at characterizing the impact of statins on macrophage polarization and comparing these to the effects of bempedoic acid, a recently registered drug for the treatment of hypercholesterolemia, which has been suggested to have a similar beneficial profile but fewer side effects. Treatment of primary murine macrophages with two different statins, i.e., simvastatin and cerivastatin, impaired phagocytotic activity and, concurrently, enhanced pro-inflammatory responses upon short-term lipopolysaccharide challenge, as characterized by an induction of tumor necrosis factor (TNF), interleukin (IL) 1β, and IL6. In contrast, no differences were observed under long-term inflammatory (M1) or anti-inflammatory (M2) conditions, and neither inducible NO synthase (iNOS) expression nor nitric oxide production was altered. Statin treatment led to extracellular-signal regulated kinase (ERK) activation, and the pro-inflammatory statin effects were abolished by ERK inhibition. Bempedoic acid only had a negligible impact on macrophage responses when compared with statins. Taken together, our data point toward an immunomodulatory effect of statins on macrophage polarization, which is absent upon bempedoic acid treatment.

Claudin-7 in keratinocytes is downregulated by the inhibition of HMG-CoA reductase and is highly expressed in the stratum granulosum of the psoriatic epidermis

BACKGROUND

Cholesterol is de novo synthesized in the upper epidermis and plays an important role in maintaining the normality of skin. Studying the impact of the inhibition of cholesterol de novo synthesis in the epidermis may help understand how skin homeostasis is regulated.

OBJECTIVE

In this study, we created a gene expression profile to investigate the effect of hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors on epidermal homeostasis.

METHODS

A microarray analysis was performed using normal keratinocytes with or without HMG-CoA reductase inhibitor (pitavastatin) treatment. Real-time PCR confirmed the reproducibility of genes with altered expression in keratinocytes treated with HMG-CoA reductase inhibitors. Among these genes, we focused on reduced expression of claudin 7 histologically confirmed by immunohistochemical staining, in situ hybridization, and immunoelectron microscopy.

RESULTS

Claudin-7 was highly expressed in the stratum granulosum of psoriatic lesions but was not expressed in the normal epidermis. Immunoelectron microscopy revealed that claudin-7 was localized in the keratohyalin granules of psoriatic lesions.

CONCLUSION

These results indicate that claudin-7 expression was regulated by HMG-CoA reductase in the epidermis and might play a pathogenic role in the keratohyalin granules found in the epidermal granular layer of psoriasis.

Effect of different selenium sources and concentrations on glutathione peroxidase activity and cholesterol metabolism of beef cattle

The objective of this study was to investigate the effects of different Se sources and concentrations on glutathione forms and cholesterol metabolism in beef cattle. Sixty-three Nellore bulls (412 ± 19 kg BW; 24 months old) were randomly assigned to a completely randomized design in a 2×3 + 1 factorial arrangement (63 pens; one animal/pen) with two Se sources (sodium selenite, ING and Se-yeast, ORG), three concentrations (0.3, 0.9 and 2.7 mg supplemental Se/kg DM), and control treatment (without Se supplementation) fed for 90 days. Blood samples were collected on d 0, 28, 56, and 84. Muscle and liver samples were collected at harvest. Hepatic GSSG (P = 0.004), GSH/GSSG ratio (P = 0.030), and GSH-Px (P = 0.004) were affected by Se source x concentration interaction. Oxidized glutathione was higher in the ORG group vs. ING at concentration 2.7 mg supplemental Se/kg DM, but at 0.3 mg supplemental Se/kg DM the ING group was higher than ORG. The liver GSH-Px activity was higher in the ORG group vs. ING at concentration 0.9 and 2.7 mg supplemental Se/kg DM. The GSH/GSSG ratio was the highest in animals fed 0.3 mg supplemental Se/kg DM of ORG. Selenium liver concentration increased linearly with the supplemental Se concentration in the diet (y = 0.0583 + 0.4254x, R 2 = 0.92, P < 0.0001), regardless of source. Total meat cholesterol was greater (P < 0.001) in CON (control) vs. SUP (supplemented, regardless source) group. The muscle GSH-Px activity was higher (P < 0.001) in SUP vs. CON and increased (P < 0.004) with increasing supplemental Se concentrations. There was an increase on VLDL, glucose, and triglycerides in ORG vs. ING (P ≤ 0.035). In general, serum Se was higher (P < 0.001) in SUP vs. CON and increased with increasing supplemental Se concentration. Lastly, the HMGCR concentration was lower (P = 0.002) in SUP (0.39 ng/mL) vs. CON (0.55 ng/mL). Selenium supplementation with different sources and concentrations has the potential to affect cholesterol metabolism by affecting GSH/GSSG ratio, GSH-Px, and the HMGCR.

Sterols, Oxysterols, and Accessible Cholesterol: Signalling for Homeostasis, in Immunity and During Development

In this article we discuss the concept of accessible plasma membrane cholesterol and its involvement as a signalling molecule. Changes in plasma membrane accessible cholesterol, although only being minor in the context of total cholesterol plasma membrane cholesterol and total cell cholesterol, are a key regulator of overall cellular cholesterol homeostasis by the SREBP pathway. Accessible cholesterol also provides the second messenger between patched 1 and smoothened in the hedgehog signalling pathway important during development, and its depletion may provide a mechanism of resistance to microbial pathogens including SARS-CoV-2. We revise the hypothesis that oxysterols are a signalling form of cholesterol, in this instance as a rapidly acting and paracrine version of accessible cholesterol.

Derlin rhomboid pseudoproteases employ substrate engagement and lipid distortion to enable the retrotranslocation of ERAD membrane substrates

Nearly one-third of proteins are initially targeted to the endoplasmic reticulum (ER) membrane, where they are correctly folded and then delivered to their final cellular destinations. To prevent the accumulation of misfolded membrane proteins, ER-associated degradation (ERAD) moves these clients from the ER membrane to the cytosol, a process known as retrotranslocation. Our recent work in Saccharomyces cerevisiae reveals a derlin rhomboid pseudoprotease, Dfm1, is involved in the retrotranslocation of ubiquitinated ERAD membrane substrates. In this study, we identify conserved residues of Dfm1 that are critical for retrotranslocation. We find several retrotranslocation-deficient Loop 1 mutants that display impaired binding to membrane substrates. Furthermore, Dfm1 possesses lipid thinning function to facilitate in the removal of ER membrane substrates, and this feature is conserved in its human homolog, Derlin-1, further implicating that derlin-mediated retrotranslocation is a well-conserved process.

ER-associated degradation is a conserved pathway of protein quality control that requires the retrotranslocation of ubiquitinated substrates from the ER to the cytoplasm for degradation. Nejatfard et al. show that derlin rhomboid pseudoproteases mediate the retrotranslocation of misfolded membrane substrates via a mechanism that is conserved from yeast to humans.

A Novel Statin Compound from Monacolin J Produced Using CYP102A1-Catalyzed Regioselective C-Hydroxylation

Statins inhibit the 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMG-CoA reductase), which is the rate-limiting enzyme in cholesterol biosynthesis. Statin therapy reduces morbidity and mortality in those who are at high risk of cardiovascular disease. Monacolin J is a statin compound, which is an intermediate in the lovastatin biosynthesis pathway, in the fungus Aspergillus terreus. It is also found in red yeast rice, which is made by culturing rice with the yeast Monascus purpureus. Monacolin J has a hydroxyl substituent at position C’-8 of monacolin L. Here, a new statin derivative from monacolin J was made through the catalysis of CYP102A1 from Bacillus megaterium. A set of CYP102A1 mutants of monacolin J hydroxylation with high catalytic activity was screened. The major hydroxylated product was C-6′a-hydroxymethyl monacolin J, whose structure was confirmed using LC–MS and NMR analysis. The C-6′a-hydroxymethyl monacolin J has never been reported before. It showed a greater ability to inhibit HMG-CoA reductase than the monacolin J substrate itself. Human liver microsomes and human CYP3A4 also showed the ability to catalyze monacolin J in producing the same product of the CYP102A1-catalyzed reaction. This result motivates a new strategy for the development of a lead for the enzymatic and chemical processes to develop statin drug candidates.

In-silico HMG-CoA reductase-inhibitory and in-vivo anti-lipidaemic/anticancer effects of carotenoids from Spondias mombin

OBJECTIVES

Inhibition of HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase, the rate rate-determining enzyme for the biogenesis of cholesterol is known to show antineoplastic effects. Therefore, this study investigates the in-silico HMG-CoA reductase (HMGCR)-inhibitory and in-vivo anti-lipidaemic/anticancer effects of carotenoids from Spondias mombin.

METHODS

Carotenoids from S. mombin leaves were characterized with the aid of liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). The characterized phytochemicals were obtained from PubChem. They were docked into the orthosteric site of human HMGCR (Protein Data Bank code 1HW8) using AutoDock 4.0 suites. DMBA (7,12-dimethylbenz[a]anthracene) model of breast cancer was treated with the carotenoids extract from S. mombin (100 mg/kg and 200 mg/kg doses) to assess its anti-lipidaemic cum anticancer effects.

KEY FINDINGS

Carotenoids from S. mombin; beta-carotene-15,15'-epoxide, astaxanthin and 7,7',8,8'-tetrahydro-β-β-carotene demonstrate HMGCR inhibition. They form hydrophobic interactions with key residues within the catalytic domain of HMGCR. The carotenoids extract exhibits anti-lipidaemic/anticancer effects, lowering serum triglyceride, LDL and cholesterol concentration. It increases HDL concentration and downregulates the expression of HMGR, AFP, CEACAM-3, BRCA-1 and HIF-1 mRNAs.

CONCLUSION

Carotenoids from S. mombin demonstrate HMG-CoA reductase (HMGCR) inhibition, anti-lipidaemic, and anticancer effects. The inhibition of HMGCR by the carotenoids extract further poses it as a potential anti-hypercholesterolaemia compounds.

Loose Morphology and High Dynamism of OSER Structures Induced by the Membrane Domain of HMG-CoA Reductase

The membrane domain of eukaryotic HMG-CoA reductase (HMGR) has the conserved capacity to induce endoplasmic reticulum (ER) proliferation and membrane association into Organized Smooth Endoplasmic Reticulum (OSER) structures. These formations develop in response to overexpression of particular proteins, but also occur naturally in cells of the three eukaryotic kingdoms. Here, we characterize OSER structures induced by the membrane domain of Arabidopsis HMGR (1S domain). Immunochemical confocal and electron microscopy studies demonstrate that the 1S:GFP chimera co-localizes with high levels of endogenous HMGR in several ER compartments, such as the ER network, the nuclear envelope, the outer and internal membranes of HMGR vesicles and the OSER structures, which we name ER-HMGR domains. After high-pressure freezing, ER-HMGR domains show typical crystalloid, whorled and lamellar ultrastructural patterns, but with wide heterogeneous luminal spaces, indicating that the native OSER is looser and more flexible than previously reported. The formation of ER-HMGR domains is reversible. OSER structures grow by incorporation of ER membranes on their periphery and progressive compaction to the inside. The ER-HMGR domains are highly dynamic in their formation versus their disassembly, their variable spherical-ovoid shape, their fluctuating borders and their rapid intracellular movement, indicating that they are not mere ER membrane aggregates, but active components of the eukaryotic cell.

Metabolic engineering of Yarrowia lipolytica for the production of isoprene

Yarrowia lipolytica has recently emerged as a prominent microbial host for production of terpenoids. Its robust metabolism and growth in wide range of substrates offer several advantages at industrial scale. In the present study, we investigate the metabolic potential of Y. lipolytica to produce isoprene. Sustainable production of isoprene has been attempted through engineering several microbial hosts; however, the engineering studies performed so far are challenged with low titers. Engineering of Y. lipolytica, which have inherent high acetyl-CoA flux could fuel precursors into the biosynthesis of isoprene and thus is an approach that would offer sustainable production opportunities. The present work, therefore, explores this opportunity wherein a codon-optimized IspS gene (single copy) of Pueraria montana was integrated into the Y. lipolytica genome. With no detectable isoprene level during the growth or stationary phase of modified strain, attempts were made to overexpress enzymes from MVA pathway. GC-FID analyses of gas collected during stationary phase revealed that engineered strains were able to produce detectable isoprene only after overexpressing HMGR (or tHMGR). The significant role of HMGR (tHMGR) in diverting the pathway flux toward DMAPP is thus highlighted in our study. Nevertheless, the final recombinant strains overexpressing HMGR (tHMGR) along with Erg13 and IDI showed isoprene titers of ~500 μg/L and yields of ~80 μg/g. Further characterization of the recombinant strains revealed high lipid and squalene content compared to the unmodified strain. Overall, the preliminary results of our laboratory-scale studies represent Y. lipolytica as a promising host for fermentative production of isoprene.

Inhibition of Orbivirus Replication by Fluvastatin and Identification of the Key Elements of the Mevalonate Pathway Involved

Statin derivatives can inhibit the replication of a range of viruses, including hepatitis C virus (HCV, Hepacivirus), dengue virus (Flavivirus), African swine fever virus (Asfarviridae) and poliovirus (Picornaviridae). We assess the antiviral effect of fluvastatin in cells infected with orbiviruses (bluetongue virus (BTV) and Great Island virus (GIV)). The synthesis of orbivirus outer-capsid protein VP2 (detected by confocal immunofluorescence imaging) was used to assess levels of virus replication, showing a reduction in fluvastatin-treated cells. A reduction in virus titres of ~1.7 log (98%) in fluvastatin-treated cells was detected by a plaque assay. We have previously identified a fourth non-structural protein (NS4) of BTV and GIV, showing that it interacts with lipid droplets in infected cells. Fluvastatin, which inhibits 3-hydroxy 3-methyl glutaryl CoA reductase in the mevalonic acid pathway, disrupts these NS4 interactions. These findings highlight the role of the lipid pathways in orbivirus replication and suggest a greater role for the membrane-enveloped orbivirus particles than previously recognised. Chemical intermediates of the mevalonic acid pathway were used to assess their potential to rescue orbivirus replication. Pre-treatment of IFNAR^(−/−) mice with fluvastatin promoted their survival upon challenge with live BTV, although only limited protection was observed.

Multicenter Study of Azole-Resistant Aspergillus fumigatus Clinical Isolates, Taiwan1

In a multicenter study, we determined a prevalence rate of 4% for azole-resistant Aspergillus fumigatus in Taiwan. Resistance emerged mainly from the environment (TR₃₄/L98H, TR₃₄/L98H/S297T/F495I, and TR₄₆/Y121F/T289A mutations) but occasionally during azole treatment. A high mortality rate observed for azole-resistant aspergillosis necessitates diagnostic stewardship in healthcare and antifungal stewardship in the environment.

PCSK9 Induces Rat Smooth Muscle Cell Proliferation and Counteracts the Pleiotropic Effects of Simvastatin

Human atherosclerotic plaque contains smooth muscle cells (SMCs) negative for the contractile phenotype (α-smooth muscle actin) but positive for proprotein convertase subtilisin/kexin type 9 (PCSK9). Thus, we generated rat SMCs which overexpressed human PCSK9 (SMCs^PCSK9) with the aim of investigating the role of PCSK9 in the phenotype of SMCs. PCSK9 overexpression in SMCs^PCSK9 led to a significant downregulation of the low-density lipoprotein receptor (Ldlr) as well as transgelin (Sm22α), a marker of the contractile phenotype. The cell proliferation rate of SMCs^PCSK9 was significantly faster than that of the control SMCs (SMCs^puro). Interestingly, overexpression of PCSK9 did not impact the migratory capacity of SMCs in response to 10% FCS, as determined by Boyden's chamber assay. Expression and activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (Hmgcr) was significantly increased in the presence of PCSK9, both in SMC^PCSK9 and after treatment with recombinant PCSK9. The transcriptional activity of sterol regulatory element-binding protein (SREBP) was also increased in the presence of PSCK9, suggesting a direct role of PCSK9 in the control of SRE-responsive genes, like HMGCR. We also observed that cholesterol biosynthesis is elevated in SMC^PCSK9, potentially explaining the increased proliferation observed in these cells. Finally, concentration-dependent experiments with simvastatin demonstrated that SMCs^PCSK9 were partially resistant to the antiproliferative and antimigratory effect of this drug. Taken together, these data further support a direct role of PCSK9 in proliferation, migration, and phenotypic changes in SMCs-pivotal features of atherosclerotic plaque development. We also provide new evidence on the role of PCSK9 in the pharmacological response to statins-gold standard lipid-lowering drugs with pleiotropic action.

Three Musketeers for Lowering Cholesterol: Statins, Ezetimibe and Evolocumab

Coronary heart disease (CHD) is closely related to hypercholesterolemia, and lowering serum cholesterol is currently the most important strategy in reducing CHD. In humans, the serum cholesterol level is determined mainly by three metabolic pathways, namely, dietary cholesterol intake, cholesterol synthesis, and cholesterol degradation in vivo. An intervention that targets the key molecules in the three pathways is an important strategy in lowering serum lipids. Statins inhibit 3-hydroxyl-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) to reduce low-density lipoprotein (LDL) by about 20% to 45%. However, up to 15% of patients cannot tolerate the potential side effects of high statin dosages, and several patients also still do not reach their optimal LDL goals after being treated with statins. Ezetimibe inhibits cholesterol absorption by targeting the Niemann-Pick C1-like 1 protein (NPC1L1), which is related to cholesterol absorption in the intestines. Ezetimibe lowers LDL by about 18% when used alone and by an additional 25% when combined with statin therapy. The proprotein convertase subtilisin/kexin type 9 (PCSK9) increases hepatic LDLR degradation, thereby reducing the liver's ability to remove LDL, which can lead to hypercholesterolemia. Evolocumab, which is a PCSK9 monoclonal antibody, can reduce LDL from baseline by 53% to 56%. The three drugs exert lipid-lowering effects by regulating the three key pathways in lipid metabolism. Combining any with the two other drugs on the basis of statin treatment has improved the lipid-lowering effect. Whether the combination of the three musketeers will reduce the side effects of monotherapy and achieve the lipid-lowering effect should be studied further in the future.

Cholesterol-lowering activity of natural mono- and sesquiterpenoid compounds in essential oils: A review and investigation of mechanisms using in silico protein-ligand docking

Mono- and sesquiterpenoids are the main chemical constituents of essential oils. Essential oils and their constituents have received increasing attention for lipid-lowering properties in both cell and animal models. Despite the chemical diversity of essential oil compounds, the effects of many of these compounds on cholesterol metabolism are highly similar. In this report, we review the literature regarding the effects of essential oils and their terpenoid constituents on cholesterol homeostasis, and explore likely mechanisms using protein-ligand docking. We identified 98 experimental and seven clinical studies on essential oils, isolated compounds, and blends; 100 of these described improvements either in blood cholesterol levels or in sterol metabolic pathways. Our review and docking analysis confirmed two likely mechanisms common to many essential oil compounds: (1) direct agonism of peroxisome-proliferator-activated receptors, and (2) direct interaction with sterol-sensing domains, motifs found in key sterol regulatory proteins including sterol regulatory element binding protein cleavage activating protein and HMG-CoA reductase. Notably, these direct interactions lead to decreased transcription and accelerated degradation of HMG-CoA reductase. Our work suggests that terpene derivatives in essential oils have cholesterol-lowering activity and could potentially work synergistically with statins, however, further high quality studies are needed to establish their clinical efficacy.

Overproduction of α-Farnesene in Saccharomyces cerevisiae by Farnesene Synthase Screening and Metabolic Engineering

Maximizing the flux of farnesyl diphosphate (FPP) to farnesene biosynthesis is the main challenge of farnesene overproduction in Saccharomyces cerevisiae. In this study, we screened α-farnesene synthase from soybean (Fsso) with a higher catalytic ability. Combining the overexpression of the mevalonate (MVA) pathway with the expression of Fsso, an engineered yeast strain producing 190.5 mg/L α-farnesene was screened with poor growth. By decreasing the copies of 3-hydroxy-3-methylglutaryl-coenzyme (HMGR) overexpressed, the titer was increased to 417.8 mg/L. Then, the coexpression of Fsso and HMGR under the control of the GAL promoter and inactivation of lipid phosphate phosphatase encoded by DPP1 promoted the titer to 1163.7 mg/L. The titer was further increased to 1477.2 mg/L at the shake flask level with better growth by the construction of a prototrophic strain. Finally, the highest α-farnesene production of 10.4 g/L in S. cerevisiae was obtained by fed-batch fermentation in a 5 L bioreactor.

Metabolic engineering of Yarrowia lipolytica for improving squalene production

The aim of this present research is to enhance the squalene production in Yarrowia lipolytica using pathway engineering and bioprocess engineering. Firstly, to improve the production of squalene, the endogenous HMG-CoA reductase (HMG1) was overexpressed in Y. lipolytica to yield 208.88 mg/L squalene. Secondly, the HMG1 and diacylglycerol acyltranferase (DGA1) were co-overexpressed, the derived recombinant Y. lipolytica SQ-1 strain produced 439.14 mg/L of squalene. Thirdly, by optimizing the fermentation medium, the improved titer of squalene with 514.34 mg/L was obtained by the engineered strain SQ-1 grown on YPD-80 medium. Finally, by optimizing the addition concentrations of acetate, citrate and terbinafine, the 731.18 mg/L squalene was produced in the engineered strain SQ-1 with the addition of 0.5 mg/L terbinafine. This work describes the highest reported squalene titer in Y. lipolytica to date. This study will provide the foundation for further engineering Y. lipolytica capable of cost-efficiently producing squalene.

Anti-hypercholesterolemic potential of diet supplemented with Anchomanes difformis and Pleurotus tuberregium tubers in high cholesterol fed rats

Background

One significant ethnomedicinal motivation behind Pleurotus tuberregium (PTT) and Anchomanes difformis (ADT) tubers is cardiovascular-related conditions treatment. This investigation is in this way planned for deciding the impact of PTT and ADT enhanced eating routine on key enzymes linked with hypercholesterolemia in elevated cholesterol fed rodents.

Methods

Rats were isolated into control group, hypercholesterolemic-prompted untreated group, hypercholesterolemic-treated groups with dietary routine containing PTT (5% and 10%), ADT (5% and 10%), 5% PTT and 5% ADT conbination and traditional medication, atorvastatin for 28 days. Ten rodents were utilized for every one of the groups.

Results

Feeding with PTT and ADT comprehensive eating regimen and their combination significantly (P < 0.05) diminished the AChE, HMG-CoA, ALT, AST, ALP, LDH and CK activities and levels of mevalonate, triglyceride (TG), total cholesterol (TC), low density lipoprotein (LDLch), atherogenic indices, MDA and ROS yet significantly increased the SOD, CAT, GPx activities, and level of HDL, GSH when contrasted with HC-initiated untreated rodents. Likewise, histopathological of liver and heart demonstrated no obsessive changes in all the treated groups when contrasted with healthy control group. HPLC fingerprinting of the PTT and ADT aqueous concentrates uncovered the nearness of ferulic acid, vanillic acid, catechin, quercetin, chlorogenic acid, ellagic acid and gallic acid. Notwithstanding, aqueous concentrate of ADT contained plentiful convergences of the polyphenolics when contrasted with PTT concentrate.

Conclusions

The tubers HMG-CoA reductase inhibitory activity could additionally support their antihypercholesterolemic use in folk medication. Accordingly, the tubers may in this way be valuable as restorative nourishment for helpful treatment of clinical conditions related hypercholesterolemia with the ADT diet holding more guarantee.

Further evidence for the involvement of mitochondrial aquaporin-8 in hepatocyte lipid synthesis

We recently provided evidence suggesting that mitochondrial aquaporin-8 (mtAQP8), a channel protein able to conduct H₂O₂, is involved in the modulation of hepatocyte cholesterogenesis. To expand that study, we cultured human hepatocyte-derived Huh-7 cells in medium with lipoprotein-deficient serum (LPDS) to induce the de novo synthesis of cholesterol and fatty acids. We found that LPDS induced mtAQP8 expression and that AQP8 gene silencing significantly down-regulated the LPDS-induced synthesis of cholesterol and fatty acids as well as the expression of the corresponding key biosynthetic enzymes, 3-hydroxy-3-methylglutaryl-CoA reductase and fatty acid synthase. Our data further support a regulatory role of mtAQP8 in hepatocyte lipid homeostasis.

A-family anti-inflammatory cyclopentenone prostaglandins: A novel class of non-statin inhibitors of HMG-CoA reductase

Disruption of the intracellular lipid balance leading to cholesterol accumulation is one of the features of cells that participate in the development of atherosclerotic lesions. Evidence form our laboratory indicates that anti-inflammatory cyclopentenone prostaglandins (cyPGs) of A- and J-family deviate lipid metabolism from the synthesis of cholesterol and cholesteryl esters to the synthesis of phospholipids in foam-cell macrophages. cyPGs possessing an α,β-unsaturated cyclopentane ring are highly electrophilic substances able to promptly react with reactive cysteines of intracellular molecules through Michael addition. On the other hand, HMG-CoA reductase (HMGCR), the enzyme responsible for the rate-limiting step in cholesterol biosynthesis, presents critically reactive cysteines at the entry of catalytic domain, particularly Cys561, that could be target of cyPG inhibition. In the present study, we showed that cyPGs (but not other non-α,β-unsaturated PGs) physically interact with HMGCR, in a dithiothreitol- and β-mercaptoethanol-sensitive way, and block the activity of the catalytic subunit of the enzyme (IC₅₀ for PGA₂ = 0.17 μM). PGA₂ inhibits HMGCR activity in cultured rat and human macrophages/macrophage-foam cells and leads to enhanced expression of HMGCR protein, as observed with statins. In cell culture models, PGA₂ effectively inhibits the reductase at non-toxic doses (e.g., 1 μM) that block cell proliferation thus suggesting that part of the well-known antiproliferative effect of PGA₂ may be due to its ability of blocking HMGCR activity, as cells cannot proliferate without a robust cholesterogenesis. Therefore, besides the powerfully anti-inflammatory and antiproliferative effects, the anticholesterogenic effects of PGA₂ should be exploited in atherosclerosis therapeutics.

HMG-CoA Reductase as Target for Drug Development

The main strategy for lowering blood cholesterol levels is through the inhibition of the NADPH-dependent HMG-CoA reductase (3-hydroxy-3-methyl-glutaryl-CoA reductase). The enzyme catalyses the reduction of HMG-CoA to mevalonate and this process is inhibited by statins that form the bulk of the therapeutic agents to treat high cholesterol since the 1970s. Newer drugs that are safer than statins are constantly being developed. The inhibition of candidate drugs to HMG-CoA reductase remains the mainstay of drug development research. The determination of the enzyme activity is important for the correct assessment of potency of the enzyme as well as determining the inhibition of potential therapeutic agents from the plant and microbial extracts. Also, this chapter covers the use of the popular four-parameter logistics model that can yield accurate estimation of the IC₅₀ values of therapeutic agents and their 95% confidence intervals.

Thymus atlanticus polyphenol-rich extract regulates cholesterol metabolism by inhibiting its biosynthesis without affecting its excretion in hamsters fed a high-fat diet

CONTEXT

Thymus atlanticus has been reported to have significant hypolipidaemic effect in animal models. However, the mechanism of this hypolipidaemic action still unknown.

OBJECTIVE

To determinate the possible mechanism(s) of hypolipidaemic action of a Thymus atlanticus polyphenol-rich extract (PRE).

MATERIALS AND METHODS

Plasma, faecal, and liver cholesterol, bile acid content in the faeces, and gene expression level of HMG-CoA reductase, CYP7A1, ABCG5 and ABCG8 were analysed after 9 weeks in hamsters feeding normal diet, high-fat diet (HFD) or HFD supplemented with 400 mg/kg body weight/day of PRE.

RESULTS

PRE significantly decreased total cholesterol content (p < .05) and HMG-CoA reductase expression (p < .05), but did not affect the faecal cholesterol, bile acid contents and CYP7A1 and ABCG5/G8 expression (p > .05).

CONCLUSION

We can conclude that the T. atlanticus extract is efficient in the alleviation of chronic hyperlipidaemia by acting as cholesterol biosynthesis inhibitor.

A dual inhibitor targeting HMG-CoA reductase and histone deacetylase mitigates neurite degeneration in LRRK2-G2019S parkinsonism

Parkinson's disease (PD) is among the most common neurodegenerative disorders, and its etiology involves both genetic and environmental factors. The leucine-rich repeat kinase (LRRK2) G2019S mutation is the most common genetic cause of familial and sporadic PD. Current treatment is limited to dopaminergic supplementation, as no disease-modifying therapy is available yet. Recent evidence reveals that HMG-CoA reductase (HMGR) inhibitors (statins) exert neuroprotection through anti-neuroinflammatory effects, and histone deacetylase (HDAC) inhibitors mitigate neurodegeneration by promoting the transcription of neuronal survival factors. We designed and synthesized a dual inhibitor, statin hydroxamate JMF3086, that simultaneously inhibits HMGR and HDAC, and examined its neuroprotective effects on LRRK2-G2019S parkinsonism. JMF3086 restored dopaminergic neuron loss in aged LRRK2-G2019S flies and rescued neurite degeneration in primary hippocampal and dopaminergic neurons isolated from transgenic LRRK2-G2019S mice. The molecular mechanisms included downregulation of ERK1/2 phosphorylation, increased anti-apoptotic Akt phosphorylation, and inhibition of GSK3β activity to maintain cytoskeletal stability in stably transfected LRRK2-G2019S SH-SY5Y human dopaminergic cells. JMF3086 also promoted a-tubulin acetylation and kinesin-1 expression, facilitating antegrade mitochondrial transport in axons. Our findings demonstrate that JMF3086 exerted beneficial effects on restoring LRRK2-G2019S neurite degeneration by maintaining microtubule stability. This dual-target compound may be a promising mechanism-based therapy for PD.

An autonomous, but INSIG-modulated, role for the sterol sensing domain in mallostery-regulated ERAD of yeast HMG-CoA reductase

HMG-CoA reductase (HMGR) undergoes feedback-regulated degradation as part of sterol pathway control. Degradation of the yeast HMGR isozyme Hmg2 is controlled by the sterol pathway intermediate GGPP, which causes misfolding of Hmg2, leading to degradation by the HRD pathway; we call this process mallostery. We evaluated the role of the Hmg2 sterol sensing domain (SSD) in mallostery, as well as the involvement of the highly conserved INSIG proteins. We show that the Hmg2 SSD is critical for regulated degradation of Hmg2 and required for mallosteric misfolding of GGPP as studied by in vitro limited proteolysis. The Hmg2 SSD functions independently of conserved yeast INSIG proteins, but its function was modulated by INSIG, thus imposing a second layer of control on Hmg2 regulation. Mutant analyses indicated that SSD-mediated mallostery occurred prior to and independent of HRD-dependent ubiquitination. GGPP-dependent misfolding was still extant but occurred at a much slower rate in the absence of a functional SSD, indicating that the SSD facilitates a physiologically useful rate of GGPP response and implying that the SSD is not a binding site for GGPP. Nonfunctional SSD mutants allowed us to test the importance of Hmg2 quaternary structure in mallostery: a nonresponsive Hmg2 SSD mutant strongly suppressed regulation of a coexpressed, normal Hmg2. Finally, we have found that GGPP-regulated misfolding occurred in detergent-solubilized Hmg2, a feature that will allow next-level analysis of the mechanism of this novel tactic of ligand-regulated misfolding.

Medicinal plants and bioactive natural compounds as inhibitors of HMG-CoA reductase: A literature review

Cardiovascular diseases (CVDs) are one of the most important causes for mortality worldwide. Elevated levels of total cholesterol, and particularly LDL-cholesterol (LDL-C) are the main risk factor for acute myocardial infarction (AMI) and ischemic heart disease. The risk of CVDs could be reduced by decreasing the elevated cholesterol levels. β-hydroxy β-methylglutaryl-CoA reductase (HMGCoAR) is the primary and rate-limiting enzyme in the cholesterol biosynthesis pathway. Recently, the crucial role of nutraceuticals in maintaining normal physiological function was established. Nutraceuticals play an important role in preventing several non-communicable diseases such as obesity, CVDs, cancer, diabetes, and reducing hyperlipidemia. Although the effect of nutraceuticals and herbal medicine on CVDs and dyslipidemia was previously investigated thoroughly, the effect of these natural products on HMGCoAR as one of the important enzymes involved in CVDs etiopathogenesis has not yet been investigated. Therefore, the major aim of this paper was to review the effects of nutraceuticals and medicinal plants on HMGCoAR. Results indicate that different types of natural foods, isolated nutrients, herbal products, and dietary supplements as nutraceuticals decrease the expression and activity of HMGCoAR. This review shows that medicinal plants and nutraceuticals could be used to decrease HMGCoAR activity as accessible and convenient and economical natural compounds to prevent dyslipidemia and CVDs.

Atorvastatin Augments Gemcitabine-Mediated Anti-Cancer Effects by Inhibiting Yes-Associated Protein in Human Cholangiocarcinoma Cells

Cholangiocarcinoma (CCA) is associated with high mortality rates because of its resistance to conventional gemcitabine-based chemotherapy. Hydroxy-methyl-glutaryl-coenzyme A reductase inhibitors (statins) reportedly exert anti-cancer effects in CCA and lower the risk of CCA; however, the underlying mechanism of these effects remains unclear. The proliferative and oncogenic activities of the transcriptional co-activator Yes-associated protein (YAP) are driven by its association with the TEA domain (TEAD) of transcription factors; thereby, upregulating genes that promote cell growth, inhibit apoptosis, and confer chemoresistance. This study investigated the effects of atorvastatin in combination with gemcitabine on the progression of human CCA associated with YAP oncogenic regulation. Both atorvastatin and gemcitabine concentration-dependently suppressed the proliferation of HuCCT-1 and KKU-M213 human CCA cells. Moreover, both agents induced cellular apoptosis by upregulating the pro-apoptotic marker BAX and downregulating the anti-apoptotic markers MCL1 and BCL2. Atorvastatin also significantly decreased the mRNA expression of the TEAD target genes CTGF, CYR61, ANKRD1, and MFAP5 in both CCA cell lines. A xenograft tumor growth assay indicated that atorvastatin and gemcitabine potently repressed human CCA cell-derived subcutaneous tumor growth by inhibiting YAP nuclear translocation and TEAD transcriptional activation. Notably, the anti-cancer effects of the individual agents were significantly enhanced in combination. These results indicate that gemcitabine plus atorvastatin could serve as a potential novel treatment option for CCA.

Lipid-Producing Ciliochoroidal Melanoma with Expression of HMG-CoA Reductase

Uveal melanoma (UM) is the commonest primary intraocular malignancy in adults. There is limited published data on lipid production in UM. Here, we describe the clinical, histological, immunohistochemical, and molecular findings in a ciliochoroidal melanoma with lipid production and expression of the enzyme HMG-CoA reductase. This case highlights an unusual UM tumour phenotype with a high-risk molecular metastatic profile and discusses tumour lipogenesis and activation of the mevalonate pathway as a potential therapeutic target in managing lipidised ciliochoroidal UM.

HMG-CoA Reductase Inhibitors as Drug Leads against Naegleria fowleri

Primary amebic meningoencephalitis (PAM), caused by the free-living ameba Naegleria fowleri, has a fatality rate of over 97%. Treatment of PAM relies on amphotericin B in combination with other drugs, but few patients have survived with the existing drug treatment regimens. Therefore, development of effective drugs is a critical unmet need to avert deaths from PAM. Since ergosterol is one of the major sterols in the membrane of N. fowleri, disruption of isoprenoid and sterol biosynthesis by small-molecule inhibitors may be an effective intervention strategy against N. fowleri. The genome of N. fowleri contains a gene encoding HMG-CoA reductase (HMGR); the catalytic domains of human and N. fowleri HMGR share <60% sequence identity with only two amino acid substitutions in the active site of the enzyme. Considering the similarity of human and N. fowleri HMGR, we tested well-tolerated and widely used HMGR inhibitors, known as cholesterol-lowering statins, against N. fowleri. We identified blood-brain-barrier-permeable pitavastatin as a potent amebicidal agent against the U.S., Australian, and European strains of N. fowleri. Pitavastatin was equipotent to amphotericin B against the European strain of N. fowleri; it killed about 80% of trophozoites within 16 h of drug exposure. Pretreatment of trophozoites with mevalonate, the product of HMGR, rescued N. fowleri from inhibitory effects of statins, demonstrating that HMGR of N. fowleri is the target of statins. Because of the good safety profile and availability for both adult and pediatric uses, consideration should be given to repurposing the fast-acting pitavastatin for the treatment of PAM.

Targeting SREBP-2-Regulated Mevalonate Metabolism for Cancer Therapy

Recently, targeting metabolic reprogramming has emerged as a potential therapeutic approach for fighting cancer. Sterol regulatory element binding protein-2 (SREBP-2), a basic helix-loop-helix leucine zipper transcription factor, mainly regulates genes involved in cholesterol biosynthesis and homeostasis. SREBP-2 binds to the sterol regulatory elements (SREs) in the promoters of its target genes and activates the transcription of mevalonate pathway genes, such as HMG-CoA reductase (HMGCR), mevalonate kinase and other key enzymes. In this review, we first summarized the structure of SREBP-2 and its activation and regulation by multiple signaling pathways. We then found that SREBP-2 and its regulated enzymes, including HMGCR, FPPS, SQS, and DHCR4 from the mevalonate pathway, participate in the progression of various cancers, including prostate, breast, lung, and hepatocellular cancer, as potential targets. Importantly, preclinical and clinical research demonstrated that fatostatin, statins, and N-BPs targeting SREBP-2, HMGCR, and FPPS, respectively, alone or in combination with other drugs, have been used for the treatment of different cancers. This review summarizes new insights into the critical role of the SREBP-2-regulated mevalonate pathway for cancer and its potential for targeted cancer therapy.

Effect of Food Preparations on In Vitro Bioactivities and Chemical Components of Fucus vesiculosus

Fucus vesiculosus is a brown macroalgae used in food and generally considered safe to be consumed, according to EU Directive (EC 258/97). The aim of this study is to analyze the effect of food preparation on F.vesiculosus of different origins on what concerns its chemical constituents and final bioactivities. The aqueous extract of the seaweeds were obtained at different temperatures, similar to food preparation and then purified by SPE. The compound identification was carried out by Liquid Chromatography High Resolution Mass Spectrometry (LC-HRMS/MS) and algae extracts microstructure were observed by Scanning Electron Microscopy (SEM). The activities were determined by using antioxidant activity, inhibition of acetylcholinesterase (AChE) and 3-hidroxi-3-methyl-glutaril-CoA (HMG-CoA) reductase (HMGR) together with Caco-2 cells line simulating the intestinal barrier. The activity of AChE and the HMGR were inhibited by the extracts giving IC₅₀ values of 15.0 ± 0.1 µg/mL and 4.2 ± 0.1 µg/mL, respectively and 45% of the cholesterol permeation inhibition. The main compounds identified were phlorotannins and peptides derivatives. The mode of preparation significantly influenced the final bioactivities. Moreover, the in vitro results suggest that the preparation of F. vesiculosus as a soup could have hypercholesterolemia lowering effect.

Investigation of HMG-CoA reductase inhibitory and antioxidant effects of various hydroxycoumarin derivatives

Cardiovascular diseases are one of the primary causes of deaths worldwide, and the development of atherosclerosis is closely related to hypercholesterolemia. As the reduction of the low-density lipoprotein cholesterol level is critical for treating these diseases, the inhibition of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase, which is essentially responsible for cholesterol biosynthesis, stands out as a key solution to lower plasma cholesterol levels. In this study, we synthesized several dihydroxycoumarins and investigated their antioxidant and in vitro HMG-CoA reductase inhibitory effects. Furthermore, we carried out in silico studies and examined the quantum-chemical properties of the coumarin derivatives. We also performed molecular docking experiments and analyzed the binding strength of each coumarin derivative. Our results revealed that compound IV displayed the highest HMG-CoA reductase inhibitory activity (IC₅₀  = 42.0 µM) in vitro. Cupric-reducing antioxidant capacity and ferric-reducing antioxidant power assays demonstrated that coumarin derivatives exhibit potent antioxidant activities. Additionally, a close relationship was found between the lowest unoccupied molecular orbital energy levels and the antioxidant activities.

Ubiquitin-mediated regulation of sterol homeostasis

Cholesterol is an essential component of mammalian membranes, and its homeostasis is strictly regulated, with imbalances causing atherosclerosis, Niemann Pick disease, and familial hypercholesterolemia. Cellular cholesterol supply is mediated by LDL-cholesterol import and de novo cholesterol biosynthesis, and both pathways are adjusted to cellular demand by the cholesterol-sensitive SREBP2 transcription factor. Cholesterol homeostasis is modulated by a wide variety of metabolic pathways and the ubiquitination machinery, in particular E3 ubiquitin ligases. In this article, we review recent progress in understanding the role of E3 ubiquitin ligases in the metabolic control of cellular sterol homeostasis.

The Innovative Potential of Statins in Cancer: New Targets for New Therapies

Numerous and different types of cancers possess the dysregulation of the mevalonate pathway as a common feature. Statins, traditionally applied in cardiovascular diseases to reduce lipid levels, subsequently have been discovered to exhibit anti-cancer activities also. Indeed, statins influence proliferation, migration, and survival of cancer cells by regulating crucial signaling proteins, such as Rho, Ras, and Rac. Recently, several studies have demonstrated that simvastatin, fluvastatin, and lovastatin are implicated in different pathways that enhance the survival time of patients with cancer under treatment in combination with antineoplastic agents. In this minireview, we present an overview of the most important studies conducted regarding the use of statins in cancer therapy up to date.

Inhibitory effects of tangeretin and trans-ethyl caffeate on the HMG-CoA reductase activity: Potential agents for reducing cholesterol levels

One of the pathways to reduce cholesterol production in the liver is through the inhibition of HMG-Coa reductase (HMGCR) by current drugs, statins. However, these have side effects if consumed in prolonged periods. Tangeretin and trans-ethyl caffeate as alternative drugs in reducing hypercholesterolemia and preventing atherosclerosis have never been reported. Their effects on inhibiting HMGCR activity were investigated through enzymatic method (in vitro and in vivo). The toxicity property was analyzed on the Serum Glutamate Oxalate Transaminase (SGOT)/Serum Glutamate Piruvate Transaminase (SGPT) levels and rat liver histology. The results showed that both compounds inhibited HMGCR activity significantly compare to the control simvastatin (p < 0.05). Tangeretin which showed very good activity in inhibiting HMGCR (83.8 of % inhibition, equal to simvastatin) was selected and used for anti-hypercholesterolemia in vivo assessment. Furthermore, tangeretin was shown to effectively reduced Total Cholesterol (TC) and Low Density Lipoprotein (LDL), and increased High Density Lipoprotein (HDL) levels significantly compared to the simvastatin group (p < 0.05). Tangeretin group was also proven to inhibit HMGCR rat liver activity significantly compare to the control simvastatin (p < 0.05). The toxicity study on the SGOT/SGPT levels and liver histology revealed that there were no side effects after administration by tangeretin. Results found that both tangeretin and trans-ethyl caffeate are potent candidates as anti-hypercholesterolemia agent in vitro. In addition, tangeretin was also shown to be safe and suitable as an alternative treatment for controlling hypercholesterolemia in vivo as well as have potency for preventing atherosclerosis.