Key Enzyme In Cholesterol Biosynthesis Research Articles

Oleanolic acid inhibits cholesterol synthesis by suppressing the expression and enzymatic activity of HMGCR

ABSTRACT This study investigated the impact of Oleanolic Acid (OA) on cholesterol metabolism and. MTT assays demonstrated that OA had no cytotoxic effects on HepG2 cells at concentrations below 20 μM. Subsequent experiments focused on 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), a key enzyme in cholesterol biosynthesis. OA significantly reduced HMGCR protein expression without affecting other enzymes. Further investigations revealed that OA reduced the protein and mRNA expression of HMGCR and its upstream regulator Sterol regulatory element binding protein-2 (SREBP-2) in HepG2 cells. OA activated Adenosine 5’-monophosphate (AMP)-activated protein kinase (AMPK), enhancing HMGCR phosphorylation and inhibiting its activity. Molecular docking experiments suggested that OA could suppress HMGCR enzymatic activity through hydrophobic interactions, reducing catalytic efficiency. Overall, OA downregulated HMGCR expression and activity, leading to decreased cholesterol synthesis. These findings highlight OA’s regulatory role in cholesterol metabolism and its potential for improving atherosclerosis (AS), supporting its application in functional food development.

Identification and validation of DHCR7 as a diagnostic biomarker involved in the proliferation and mitochondrial function of breast cancer.

Energy metabolism has a complex intersection with pathogenesis and development of breast cancer (BC). This allows for the possibility of identifying energy-metabolism-related genes (EMRGs) as novel prognostic biomarkers for BC. 7-dehydrocholesterol reductase (DHCR7) is a key enzyme of cholesterol biosynthesis involved in many cancers, and in this paper, we investigate the effects of DHCR7 on the proliferation and mitochondrial function of BC. EMRGs were identified from the Gene Expression Omnibus (GEO) and MSigDB databases using bioinformatics methods. Key EMRGs of BC were then identified and validated by functional enrichment analysis, interaction analysis, weighted gene co-expression network analysis (WGCNA), least absolute shrinkage and selection operator (LASSO) regression, Cox analysis, and immune infiltration. Western blot, qRT-PCR, immunohistochemistry (IHC), MTT assay, colony formation assay and flow cytometry assay were then used to analyze DHCR7 expression and its biological effects on BC cells. We identified 31 EMRGs in BC. These 31 EMRGs and related transcription factors (TFs), miRNAs, and drugs were enriched in glycerophospholipid metabolism, glycoprotein metabolic process, breast cancer, and cell cycle. Crucially, DHCR7 was a key EMRG in BC identified and validated by WGCNA, LASSO regression and receiver operating characteristic (ROC) curve analysis. High DHCR7 expression was significantly associated with tumor immune infiltration level, pathological M, and poor prognosis in BC. In addition, DHCR7 knockdown inhibited cell proliferation, induced apoptosis and affected mitochondrial function in BC cells. DHCR7 was found to be a key EMRG up-regulated in BC cells. This study is the first to our knowledge to report that DHCR7 acts as an oncogene in BC, which might become a novel therapeutic target for BC patients.

Impact of statins in the liver: A bane or a boon?

Treatment of hypercholesterolemia with statins is considered one of the cornerstones in the management of atherosclerotic cardiovascular diseases. Statins exert their hypolipidemic effects by inhibiting HMG-CoA reductase, the key enzyme in cholesterol biosynthesis. Beyond cholesterol reduction, statins exhibit pleiotropic effects, including anti-inflammatory, antioxidant, and antiproliferative actions, making them valuable in mitigating atherosclerotic and non-atherosclerotic diseases. Though concerns of hepatotoxicity have been associated with the use of statins, extensive evidence suggests that the risk of statin-induced liver injury (SILI) is rare, with an incidence of <1%. Hepatic adverse effects include reversible asymptomatic transaminase elevation (most frequent), hepatitis, cholestasis, and rarely acute liver failure. While hepatotoxicity concerns should not be dismissed, the evidence overwhelmingly supports the safety of statins. Contrary to the myth of statin hepatotoxicity, real-world data and extensive research emphasize the safety and benefits of statins. They are therapeutic in various liver-related conditions, mainly non-alcoholic fatty liver disease. This scientific review aims to provide a comprehensive overview of statins, shedding light on their mechanism of action, hepatotoxicity concerns, and therapeutic potential in various liver-related conditions.

10007-ACT-2 FIRST IN HUMAN STUDY OF DSP-0390, AN ORAL EMOPAMIL BINDING PROTEIN (EBP) INHIBITOR, IN RECURRENT HIGH-GRADE GLIOMA (HGG): PRELIMINARY RESULTS

Abstract BACKGROUND Cholesterol in the brain is derived wholly from de novo biosynthesis as the blood-brain barrier prevents uptake from the circulation. The overexpression of cholesterol synthesis genes is associated with decreased survival in glioblastoma (GBM), suggesting that gliomas may be sensitive to the inhibition of cholesterol biosynthesis. DSP-0390 is an investigational small molecule that inhibits EBP, a key enzyme in cholesterol biosynthesis. Preclinical studies demonstrated antitumor activity of DSP-0390 in orthotopic xenograft GBM models. METHODS This phase I dose escalation study aims to assess the safety, PK, PD, and preliminary antitumor activity of oral DSP-0390 monotherapy for recurrent HGG (NCT05023551). Key eligibility criteria include histologically confirmed grade III or IV glioma (WHO 2016); treatment with ≥1 prior therapy; no treatment options beyond standard of care; KPS ≥70. RESULTS As of 9 May 2023, 24 patients (37.5% women) were enrolled across 6 dose levels (20 mg QD to 240 mg QD) with a median age of 51 years (range 24-76) including 17 (70.8 %) with GBM, 3 (12.5%) with anaplastic astrocytoma and 2 (8.3%) with anaplastic oligodendroglioma. Ten patients (41.7%) had IDH mutant tumors. Four patients (16.7%) were on stable dose of corticosteroids at baseline, of which 2 were able to discontinue or dose reduce the corticosteroid while on DSP-0390. There were no reported DLTs. The most common treatment-related TEAEs included grade 1 or 2 nausea (7 patients [29.2%]) and alanine aminotransferase increased (6 patients [25.0%]). Only one grade 3 related AE (dry skin) was noted. Two patients with IDH mutant grade 3 glioma had tumor reduction and remain on DSP-0390 for ≥9 months. Dose dependent changes in PK and PD were observed. CONCLUSIONS DSP-0390 has been well tolerated to date with dose escalation ongoing. A dose response relationship was observed between PK and PD biomarkers.

CTNI-67. FIRST IN HUMAN STUDY OF DSP-0390, AN ORAL EMOPAMIL BINDING PROTEIN (EBP) INHIBITOR, IN RECURRENT HIGH-GRADE GLIOMA (HGG): PRELIMINARY RESULTS

Abstract BACKGROUND Cholesterol in the brain is derived wholly from de novo biosynthesis as the blood-brain barrier prevents uptake from the circulation. The overexpression of cholesterol synthesis genes is associated with decreased survival in glioblastoma (GBM), suggesting that gliomas may be sensitive to the inhibition of cholesterol biosynthesis. DSP-0390 is an investigational small molecule that inhibits EBP, a key enzyme in cholesterol biosynthesis. Preclinical studies demonstrated antitumor activity of DSP-0390 in orthotopic xenograft GBM models. METHODS This phase I dose escalation study aims to assess the safety, PK, PD, and preliminary antitumor activity of oral DSP-0390 monotherapy for recurrent HGG (NCT05023551). Key eligibility criteria include histologically confirmed grade III or IV glioma (WHO 2016); treatment with ≥ 1 prior therapy; no treatment options beyond standard of care; KPS ≥ 70. RESULTS As of 9 May 2023, 24 patients (37.5% women) were enrolled across 6 dose levels (20 mg QD to 240 mg QD) with a median age of 51 years (range 24-76) including 17 (70.8 %) with GBM, 3 (12.5%) with anaplastic astrocytoma and 2 (8.3%) with anaplastic oligodendroglioma. Ten patients (41.7%) had IDH mutant tumors. Four patients (16.7%) were on stable dose of corticosteroids at baseline, of which 2 were able to discontinue or dose reduce the corticosteroid while on DSP-0390. There were no reported DLTs. The most common treatment-related TEAEs included grade 1 or 2 nausea (7 patients [29.2%]) and alanine aminotransferase increased (6 patients [25.0%]). Only one grade 3 related AE (dry skin) was noted. Two patients with IDH mutant grade 3 glioma had tumor reduction and remain on DSP-0390 for ≥ 9 months. Dose dependent changes in PK and PD were observed. CONCLUSIONS DSP-0390 has been well tolerated to date with dose escalation ongoing. A dose response relationship was observed between PK and PD biomarkers.

High Plant Protein Diet Ameliorated Hepatic Lipid Accumulation Through the Modulation of Gut Microbiota.

Substituting plant protein for animal protein has emerged as a promising strategy for managing atherogenic lipids. However, the impact of long-term intake of a high plant protein diet (HPD) on hepatic lipid disorder remains unclear. Eight-week-old apolipoprotein E deficient (apoE-/- ) mice are fed with either a normal protein diet (NCD) or HPD for 12 weeks. HPD intervention results in decreased body weight accompanied by increased energy expenditure, with no significant effect on glycemic control. Long-term intake of HPD improves the serum and hepatic lipid and cholesterol accumulation by suppressing hepatic squalene epoxidase (SQLE) expression, a key enzyme in cholesterol biosynthesis. Integrated analysis of 16S rDNA sequencing and metabolomics profiling reveals that HPD intervention increases the abundance of the Lachnospiraece family and serum levels of 12,13-DiHOME. Furthermore, in vivo studies demonstrate that 12,13-DiHOME significantly inhibits lipid accumulation, as well as SQLE expression induced by oleic acid in HepG2 cells. Diet rich in plant protein diet alleviates hyperlipidemia via increased microbial production of 12,13-DiHOME.

Red Yeast Rice for the Improvement of Lipid Profiles in Mild-to-Moderate Hypercholesterolemia: A Narrative Review.

Reducing low-density lipoprotein cholesterol (LDL-C) levels is a key target for lowering cardiovascular risk and preventing atherosclerotic cardiovascular disease (ASCVD). Red yeast rice (RYR) is a nutraceutical widely used as a lipid-lowering dietary supplement. The main cholesterol-lowering components of RYR are monacolins, particularly monacolin K, which is structurally identical to lovastatin and targets the same key enzyme of cholesterol biosynthesis. RYR supplementation reduces LDL-C levels by approximately 15-34% versus placebo, with a similar effect to low-dose, first-generation statins in subjects with mild-to-moderate dyslipidemia. RYR has also demonstrated beneficial reductions of up to 45% versus placebo in the risk of ASCVD events in secondary prevention studies. RYR at a dose that provides about 3 mg/d of monacolin K is well tolerated, with an adverse event profile similar to that of low-dose statins. RYR is therefore a treatment option for lowering LDL-C levels and ASCVD risk for people with mild-to-moderate hypercholesterolemia who are ineligible for statin therapy, particularly those who are unable to implement lifestyle modifications, and also for people who are eligible for statin therapy but who are unwilling to take a pharmacologic therapy.

The main side effects of statins in clinical practice

Statins have long occupied a central place in cardiovascular medicine, being an integral component of the prevention and treatment of atherosclerotic cardiovascular diseases (coronary heart disease and its main clinical forms, angina pectoris and myocardial infarction; transient ischemic attacks, ischemic strokes, etc.). By blocking a key enzyme of cholesterol biosynthesis, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA-reductase), statins normalize the parameters of the lipid spectrum, primarily, the serum levels of atherogenic low-density lipoprotein cholesterol. However, in addition to the beneficial effects of statins, side effects are also characteristic, which are a significant problem in modern clinical practice due to the fact that they can cause dangerous disorders, forcing physicians to reduce dosages or completely cancel these drugs. Understanding the side effects and the mechanisms underlying their formation is important for improving the measures for the early detection, prevention and treatment of those disorders. This article discusses such side effects of statins as myotoxicity, hepatotoxicity, nephrotoxicity. The pathogenetic mechanisms underlying these toxic effects of statins are discussed. A particular attention is paid to the effect of statins on the oxidative stress, the mechanisms of oxidative damage to cellular macromolecules (lipids, proteins and DNA) and their potential role in the development of myotoxicity, hepatotoxicity and nephrotoxicity.

Curcumin sensitizes response to cytarabine in acute myeloid leukemia by regulating intestinal microbiota

PurposeTo address whether Curcumin has synergistic effect with cytarabine (Ara-C) in treating acute myeloid leukemia (AML).MethodsA xenograft AML mouse model was established by injecting HL-60 cells into tail vein of mice to assess the function of Curcumin. Mononuclear cells (MNCs) isolated from AML mice and AML cell lines were used to examine the effect of Curcumin. Metagenomics and metabolomics were used to evaluate the alteration of intestinal microbiota and the change of metabolites in MNCs.ResultsCurcumin treatment sensitized response to Ara-C in MNCs of AML mice, but had no direct effect on AML cell lines. Metagenomics revealed an alteration of intestinal microbiota with Curcumin treatment, which contributes to sensitized response to Ara-C. Curcumin treatment led to enhanced intestinal intact to sensitize response to Ara-C in AML mice, through reducing mucus degrading bacteria. Metabolomics demonstrated that Curcumin treatment led to decreased cholesterol in MNCs of AML mice. Further study proved that Curcumin treatment resulted in inhibition of SQLE, a key enzyme of cholesterol biosynthesis, to increase sensitivity to Ara-C.ConclusionCurcumin sensitizes response to Ara-C through regulating microbiota, highlighting the importance of intestinal intact strengthening in chemoresistant therapy. Moreover, aiming at cholesterol synthesis is promising in AML treatment.

The estrogen receptor beta agonist liquiritigenin enhances the inhibitory effects of the cholesterol biosynthesis inhibitor RO 48-8071 on hormone-dependent breast-cancer growth.

Most hormone-dependent human breast cancers develop resistance to anti-hormone therapy over time. Our goal was to identify novel treatment strategies to avoid this drug resistance and thereby control hormone-dependent breast cancer. Sulforhodamine B assays were used to measure viability of cultured human breast-cancer cells. BT-474 cell tumor xenografts in nude mice were used to evaluate tumor growth. Immunohistochemistry was used to assess estrogen-receptor and angiogenesis-marker expression, as well as apoptosis, in tumor-xenograft tissues. MCF-7 and BT-474 breast-cancer cells treated with either RO 48-8071 <[4'-[6-(Allylmethylamino)hexyloxy]-4-bromo-2'-fluorobenzophenone fumarate] [RO]; a small-molecule inhibitor of oxidosqualene cyclase, a key enzyme in cholesterol biosynthesis> or liquiritigenin [LQ; an estrogen receptor (ER) β agonist] exhibited significantly reduced viability in vitro. RO + LQ treatment further significantly reduced cell viability. Administration of RO, LQ, or RO + LQ significantly inhibited growth of BT-474 tumor xenografts in vivo. RO, LQ, or RO + LQ reduced ERα but induced ER β expression in tumor xenografts. Both compounds significantly reduced angiogenesis-marker expression and increased apoptosis in tumor xenografts; use of RO + LQ significantly enhanced the effects observed with a single agent. The ERβ ligand LQ significantly enhanced the inhibition of breast-cancer cell viability and tumor-xenograft growth by RO. The anti-tumor properties of RO may in part be due to an off-target effect that reduces ERα and increases ERβ, the latter of which can then interact with LQ to promote anti-proliferative effects. The RO + LQ combination may have value when considering novel treatment strategies for hormone-dependent breast cancer.

Pharmacogenomics of statins: lipid response and other outcomes in Brazilian cohorts.

Statins are inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in cholesterol biosynthesis, that arehighly effective in reducing plasma low-density lipoprotein (LDL) cholesterol and decreasing the risk of cardiovascular events. In recent years, a multitude of variants in genes involved in pharmacokinetics (PK) and pharmacodynamics (PD) have been suggested to influence the cholesterol-lowering response. However, the vast majority of studies have analyzed the pharmacogenetic associations in populations in Europe and the USA, whereas data in other populations, including Brazil, are mostly lacking. This narrative review provides an update of clinical studies on statin pharmacogenomics in Brazilian cohorts exploring lipid-lowering response, adverse events and pleiotropic effects. We find that variants in drug transporter genes (SLCO1B1 and ABCB1) positively impacted atorvastatin and simvastatin response, whereas variants in genes of drugmetabolizing enzymes (CYP3A5) decreased response. Furthermore, multiple associations of variants in PD genes (HMGCR, LDLR and APOB) with statin response were identified. Few studies have explored statin-related adverse events, and only ABCB1 but not SLCO1B1 variants were robustly associated with increased risk in Brazil. Statin-related pleiotropic effects were shown to be influenced by variants in PD (LDLR, NR1H2) and antioxidant enzyme (NOS3, SOD2, MTHFR, SELENOP) genes. The findings of these studies indicate that statin pharmacogenomic associations are distinctly different in Brazil compared to other populations. This review also discusses the clinical implications of pharmacogenetic studies and the rising importance of investigating rare variants to explore their association with statin response.

Abstract 162: Cholesterol metabolism gene expression and prostate cancer-specific outcomes in radiotherapy-treated patients

Abstract Introduction Dysregulated lipid metabolism is a hallmark of prostate cancer. Furthermore, use of the cholesterol lowering statin drugs has been linked to a reduced risk of lethal prostate cancer. To understand the molecular pathways implicated in this relationship, we examined the association between differential expression of genes involved in intratumoral cholesterol metabolism in prostate tumor biopsies and prostate cancer-specific outcomes. Methods Tumor biopsy gene expression data from 242 men diagnosed with localized/locally advanced prostate cancer and treated with radiotherapy and androgen deprivation therapy was analyzed. A total of 71 genes involved in cholesterol transport, biosynthesis and regulation were selected from the Reactome pathway database, with additional genes involved in cholesterol metabolism extracted from literature. For each gene, expression levels were dichotomized by median expression level. Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations of gene expression with biochemical recurrence and metastasis. Models were adjusted for age at diagnosis and Gleason score. Multiple-testing correction was performed using the Bonferroni correction method. Results During a median follow-up of 10.4 years, 72 (30%) patients experienced biochemical recurrence and 32 (13%) developed metastatic disease. Differential expression of several genes was found to be associated with risk of biochemical recurrence and metastasis, though none remained statistically significant following Bonferroni correction. However, several genes showed similar patterns of association with risk of biochemical recurrence and of metastasis, an association which remained similar following adjustment for age and Gleason score. Low (below median) expression of FDFT1, a gene encoding squalene synthase, a key enzyme in cholesterol biosynthesis, was associated with an increased risk of biochemical recurrence (HR 1.87; 95% CI, 1.15-3.01) and metastasis (HR 3.52; 95% CI, 1.52-8.16). High (above median) expression of SLCO1B3, a gene encoding an organic anion transporting polypeptide transporting a variety of small molecules including statins, was associated with higher risk of biochemical recurrence (HR 2.14; 95% CI, 1.31-3.49) and metastasis (HR 2.70; 95% CI, 1.25-5.90). Conclusion These hypothesis-generating results point to a potential role for altered intratumoral cholesterol metabolism in prostate cancer-specific outcomes. Our findings highlighting differential expression of FDFT1 and SLCO1B3, genes involved in cholesterol biosynthesis and anion transport, respectively, in association with risk of biochemical recurrence and metastasis may provide clues as to the mechanistic pathways of most importance. Validation in other prostate cancer gene expression datasets is required. Citation Format: Sarah J. Winter, Sophia Halliday, Konrad H. Stopsack, Sarah O. Osman, Alan R. Hounsell, Gillian Prue, Suneil Jain, Emma H. Allott. Cholesterol metabolism gene expression and prostate cancer-specific outcomes in radiotherapy-treated patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 162.

Bempedoic Acid

ATP-Citrate-Lyase is a key enzyme of cholesterol biosynthesis. Its liver-specific inhibition by the bempedoic acid opens new possibilities to effectively escalate a cholesterol-lowering therapy while avoiding muscle-related side effects. Herein, we present the properties of this new first-in-class pharmaceutical agent and discuss potential consequences for pharmacotherapy.

Squalene epoxidase-induced cholesteryl ester accumulation promotes nasopharyngeal carcinoma development by activating PI3K/AKT signaling.

Nasopharyngeal carcinoma (NPC) is a common malignant tumor and a major cause of mortality and morbidity in southern China. However, the mechanism is still elusive. Here, we focused on studying the role of squalene epoxidase (SQLE), a key enzyme of cholesterol biosynthesis, in the progression of NPC. Clinical study revealed that SQLE expression was significantly upregulated in NPC tissues compared to normal tissues from mRNA level and patients with high expression of SQLE showed a poor prognosis. In vitro experiments showed that SQLE overexpression led to a significant proliferation of cells whereas SQLE knockdown showed an opposite result. In vivo studies also showed that SQLE promoted tumor growth in nude mice. Further study revealed that SQLE promoted NPC proliferation by cholesteryl ester accumulation instead of cholesterol. Mechanism studies indicated that cholesteryl ester promoted NPC cell proliferation by activating the PI3K/AKT pathway and inhibition of this pathway in SQLE‐overexpressed or cholesteryl ester‐treated cells resulted in a significant reduction of NPC cell proliferation. These results indicate that the oncogenic effect of SQLE in NPC mainly resulted from cholesteryl ester accumulation and PI3K/AKT is a promising target for NPC with SQLE overexpression.

Phytoconstituents of an ethanolic pod extract of Prosopis cineraria triggers the inhibition of HMG-CoA reductase and the regression of atherosclerotic plaque in hypercholesterolemic rabbits

BackgroundThe HMG-CoA reductase is key enzyme of cholesterol biosynthesis which potentially contributes in management of hypercholesterolemia. The present study was designed to assess the inhibitory effect of phytoconstituents of an ethanolic extract of Prosopis cineraria pods on HMG – CoA reductase and regression potential of atherosclerotic plaque.MethodsHealthy, adult male, albino rabbits in which hypercholesterolemia was induced by supplying the high fat diet and a supplement of cholesterol powder with coconut oil (500 mg/5 ml/Day/kg body weight) for 15 days, were used as a disease model. Phytochemical analysis of an ethanolic extract Prosopis cineraria pods was conducted using LCMS, GCMS and FTIR analysis. Further, in-vitro, in-vivo and in-silico assessments were performed.ResultsThe in-vitro assessment of HMG -CoA reductase activity indicated a 67.1 and 97.3% inhibition by the extract and a standard drug (Pravastatin), respectively. Additionally, an in-silico evaluation was made using appropriate docking software and results also indicated as significant interactions of the identified compounds with the target enzyme. Treatment of rabbits with the ethanolic extract of P. cineraria pod resulted in significant (P ≤ 0.001) reductions in total cholesterol, LDL cholesterol, VLDL cholesterol, and triglyceride. Accordingly, reductions were occurred in atherosclerotic plaque, intima and media of aortal wall along with lumen volume of the aorta significantly increased (P ≤ 0.001).ConclusionIt can be illustrating that the ethanolic extract of Prosopis cineraria pod contains potent bioactive phytocompounds might be inhibit HMG – CoA reductase and have regression potential of atherosclerotic plaque.

Phototransformations of pitavastatin - The inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase

Pitavastatin (PTV) - an important cholesterol-lowering drug, is one of the most potent inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, the key enzyme in cholesterol biosynthesis. PTV is sensitive to light, and upon exposure to radiation from the UVA and UVC regions undergoes partial decomposition forming photoproducts. In this study both experimental and theoretical methods were used to get insight into photophysical and photochemical properties of PTV with respect to its primary photochemistry. The PTV photodegradation quantum yield value was determined to be Ф = 0.011 (±0.002). PTV was found to undergo an intersystem crossing, however 3PTV* was formed with a low efficiency due partially to fluorescent properties exhibited by the statin. The lifetime of the excited singlet 1PTV* was calculated to be about 130 (±20) ps. 3PTV* was shown to be not involved in the formation of PTV primary photoproduct. Both PTV and its primary photoproduct were found to be able to generate singlet oxygen. Two different structures of PTV primary photoproduct were assumed to be possible on the basis of experimental measurements and quantum chemical modelling. The study provides mechanistic explanations of the both structures formation. The obtained results address to the lack of data existing till now in the scientific literature with regard to PTV phototransformations, are of great importance for safety of patients who require therapy with the statin, and should be taken into account in studies of the drug’s side effects.

Abstract 2769: A squalene epoxidase-cholesterolaxis drives colorectal cancer progression and metastatic dissemination

Abstract Links between cholesterol and cancer are well-documented, but the mechanisms remain unclear. Squalene epoxidase (SQLE), a key enzyme in cholesterol biosynthesis degraded by excess cholesterol, is suggested as a proto-oncogene. Paradoxically, we found reduced SQLE in aggressive colorectal cancer (CRC); low SQLE being associated with a shortened survival of CRC patients. This was confirmed in a spontaneous CRC metastasis mouse model where SL-15 reduction, by either a high-cholesterol regimen or genetic knockdown, strikingly promotes CRC aggressiveness through the production of migratory cancer stem cells. Experiments in CRC cell-lines demonstrated that SQLE reduction helps overcome constraints for malignant transformation. Specifically, we uncovered a surprising interaction of SQLE with GSK3β and p53. Depletion of SQLE disrupted the GSK3β/p53 complex, resulting in a metastatic phenotype. Our findings provide mechanistic insights into the link between cholesterol and CRC, identifying SQLE as a key regulator in CRC progression and potentially a biomarker for risk assessment. Citation Format: Soo Young Jun, Andrew J. Brown, Ji-Yong Yoon, Jeong-Ju Lee, Ngee Kiat Chua, Jin OK Yang, Ju-Sik Min, Insu Jang, Su-Jin Jeon, Min-Hyuk Choi, Tae-Ik Choi, Cheol-Hee Kim, Nam-Soon Kim. A squalene epoxidase-cholesterolaxis drives colorectal cancer progression and metastatic dissemination [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2769.

Phytosterol and γ-Oryzanol Conjugates: Synthesis and Evaluation of their Antioxidant, Antiproliferative, and Anticholesterol Activities.

Fifteen new multifunctional conjugates were designed and synthesized by chemically linking the steroidal framework of natural occurring γ-oryzanol and γ-oryzanol-derived phytosterols to a wide range of bioactive natural compounds (fatty acids, phenolic acids, amino acids, lipoic acid, retinoic acid, curcumin, and resveratrol). Starting from γ-oryzanol, which is the main component of rice bran oil, this study was aimed at assessing if the conjugation strategy might enhance some γ-oryzanol bioactivities. The antioxidant activity was evaluated through three different mechanisms, namely, DPPH-scavenging activity, metal-chelating activity, and β-carotene-bleaching inhibition. Measurement of the in vitro cell growth inhibitory effects on three different human cancer cellular lines was also carried out, and the potential hypocholesterolemic effect was studied. Compounds 10 and 15 displayed an improved antioxidant activity, with respect to that of γ-oryzanol. Compounds 2, 6, and 12 exerted an antiproliferative activity in the low micromolar range against HeLa and DAOY cells (GI50 < 10 μM). As for the claimed hypocholesterolemic effect of γ-oryzanol, none of the synthesized compounds inhibited the 3-hydroxy-3-methylglutaryl-coenzyme A reductase, a key enzyme in cholesterol biosynthesis.

Black Tea Theaflavins Are Potent Inhibitors of Squalene Epoxidase, A Key Enzyme in Cholesterol Biosynthesis

Black Tea Theaflavins Are Potent Inhibitors of Squalene Epoxidase, A Key Enzyme in Cholesterol Biosynthesis

Plasmalogen homeostasis - regulation of plasmalogen biosynthesis and its physiological consequence in mammals.

Plasmalogens, mostly ethanolamine-containing alkenyl ether phospholipids, are a major subclass of glycerophospholipids. Plasmalogen synthesis is initiated in peroxisomes and completed in the endoplasmic reticulum. The absence of plasmalogens in several organs of peroxisome biogenesis-defective patients suggests that the de novo synthesis of plasmalogens plays a pivotal role in its homeostasis in tissues. Plasmalogen synthesis is regulated by modulating the stability of fatty acyl-CoA reductase 1 on peroxisomal membranes, a rate-limiting enzyme in plasmalogen synthesis, by sensing plasmalogens in the inner leaflet of plasma membranes. Dysregulation of plasmalogen homeostasis impairs cholesterol biosynthesis by altering the stability of squalene monooxygenase, a key enzyme in cholesterol biosynthesis, implying physiological consequences of plasmalogen homeostasis with respect to cholesterol metabolism in cells, as well as in organs such as the liver.