Cholesterol Biosynthesis Pathway Research Articles

Synergistic effects of PARP inhibition and cholesterol biosynthesis pathway modulation.

An in-depth multi-omic molecular characterisation of poly(adenosine 5'-diphosphate [ADP]-ribose) polymerase (PARP) inhibitors revealed a distinct poly-pharmacology of niraparib (Zejula®) mediated by its interaction with lanosterol synthase (LSS), which is not observed with other PARP inhibitors. Niraparib, in a similar way to the LSS inhibitor Ro-48-8071, induced activation of the 24,25-epoxysterol shunt pathway, which is a regulatory signalling branch of the cholesterol biosynthesis pathway. Interestingly, the combination of a LSS inhibitor with a PARP inhibitor that does not bind to LSS, such as olaparib, had an additive effect on killing of cancer cells to levels comparable to Niraparib as single agent. In addition, the combination of PARP inhibitors and statins, inhibitors of HMGCR, an enzyme catalysing the rate-limiting step in the mevalonate pathway, had a synergistic effect on tumor cell killing in cell lines and patient-derived ovarian tumor organoids. These observations suggest that concomitant inhibition of cholesterol biosynthesis pathway and PARP activity might result in stronger efficacy of these inhibitors against tumor types highly dependent on cholesterol metabolism.

Temporal changes in mouse hippocampus transcriptome after pilocarpine-induced seizures.

Status epilepticus (SE) is a seizure lasting more than 5 min that can have lethal consequences or lead to various neurological disorders, including epilepsy. Using a pilocarpine-induced SE model in mice we investigated temporal changes in the hippocampal transcriptome. We performed mRNA-seq and microRNA-seq analyses at various times after drug treatment. At 1 h after the start of seizures, hippocampal cells upregulated transcription of immediate early genes and genes involved in the IGF-1, ERK/MAPK and RNA-PolII/transcription pathways. At 8 h, we observed changes in the expression of genes associated with oxidative stress, overall transcription downregulation, particularly for genes related to mitochondrial structure and function, initiation of a stress response through regulation of ribosome and translation/EIF2 signaling, and upregulation of an inflammatory response. During the middle of the latent period, 36 h, we identified upregulation of membrane components, cholesterol synthesis enzymes, channels, and extracellular matrix (ECM), as well as an increased inflammatory response. At the end of the latent period, 120 h, most changes in expression were in genes involved in ion transport, membrane channels, and synapses. Notably, we also elucidated the involvement of novel pathways, such as cholesterol biosynthesis pathways, iron/BMP/ferroptosis pathways, and circadian rhythms signaling in SE and epileptogenesis. These temporal changes in metabolic reactions indicate an immediate response to injury followed by recovery and regeneration. CREB was identified as the main upstream regulator. Overall, our data provide new insights into molecular functions and cellular processes involved at different stages of seizures and offer potential avenues for effective therapeutic strategies.

Temporal changes in mouse hippocampus transcriptome after pilocarpine-induced seizures

IntroductionStatus epilepticus (SE) is a seizure lasting more than 5 min that can have lethal consequences or lead to various neurological disorders, including epilepsy. Using a pilocarpine-induced SE model in mice we investigated temporal changes in the hippocampal transcriptome.MethodsWe performed mRNA-seq and microRNA-seq analyses at various times after drug treatment.ResultsAt 1 h after the start of seizures, hippocampal cells upregulated transcription of immediate early genes and genes involved in the IGF-1, ERK/MAPK and RNA-PolII/transcription pathways. At 8 h, we observed changes in the expression of genes associated with oxidative stress, overall transcription downregulation, particularly for genes related to mitochondrial structure and function, initiation of a stress response through regulation of ribosome and translation/EIF2 signaling, and upregulation of an inflammatory response. During the middle of the latent period, 36 h, we identified upregulation of membrane components, cholesterol synthesis enzymes, channels, and extracellular matrix (ECM), as well as an increased inflammatory response. At the end of the latent period, 120 h, most changes in expression were in genes involved in ion transport, membrane channels, and synapses. Notably, we also elucidated the involvement of novel pathways, such as cholesterol biosynthesis pathways, iron/BMP/ferroptosis pathways, and circadian rhythms signaling in SE and epileptogenesis.DiscussionThese temporal changes in metabolic reactions indicate an immediate response to injury followed by recovery and regeneration. CREB was identified as the main upstream regulator. Overall, our data provide new insights into molecular functions and cellular processes involved at different stages of seizures and offer potential avenues for effective therapeutic strategies.

P-356 Fertility preservation for patients with breast cancer: altered response to ovarian stimulation and loss of cholesterol homeostasis in ovarian follicles

Abstract Study question Does the presence of breast cancer alter the ovarian response to hormonal stimulation and the cholesterol homeostasis in ovarian follicles? Summary answer The deleterious impact of breast cancer on the ovarian response might be link to an alteration of the cholesterol biosynthesis in cumulus cells. What is known already Breast cancer is the most frequent cancer in reproductive-aged women. The cancer itself seems to exert a deleterious impact on the ovarian functions. Indeed, cancer patients who undergo fertility preservation before cancer therapy initiation show a poorer response to ovarian stimulation than healthy women. Nevertheless, this impact remains controversial, and the mechanisms by which the cancer impairs the ovarian functions are poorly understood. To our knowledge, no study has yet evaluated the impact of breast cancer on the cholesterol biosynthesis pathway in human cumulus cells, a pathway essential for oocyte competence to maturation and fertilization. Study design, size, duration 30 patients with breast cancer (10 triple negative (TNBC), 10 hormone-receptor positive (HR+) and 10 HER2 positive (HER2+)) and 30 women oocytes donors undergoing oocyte cryopreservation will be included from January 2019. We assess ovarian response to stimulation (number, quality of retrieved oocytes; total FSH dose). We quantify the level of enzymes and regulators of the cholesterol biosynthesis pathway in cumulus cells (CC) by RT-qPCR. We plan to quantify cholesterol levels in follicular fluids (FF). Participants/materials, setting, methods Since January 2019, 25 breast cancer patients (9 TNBC, 8 HR+ and 8 HER2+) and 30 oocytes donors (control group) under 37 years old have been included. Ovarian stimulation was performed with antagonist protocol. Following ovarian pick up and denudation, CC and FF were collected. After total RNAs extraction from CC, the expression levels of enzymes and regulators of the cholesterol biosynthesis pathway were quantified by RT-qPCR. Cholesterol levels will be quantified in FF. Main results and the role of chance The clinico-biological characteristics (age, BMI) are comparable between cancer patients and the control group (p > 0.05). Serum AMH levels are lower in the TNBC subgroup (2.3±1.6 ng/mL) than in the control group (4.7±2.8 ng/mL, p = 0.04). A poorer ovarian response to ovarian stimulation is observed in the breast cancer group compared with the control group (number of mature oocytes: 9.4±5.2 vs. 14.5±7.7, p = 0.007). Among the cancer patients group, the TNBC subgroup shows the poorest ovarian response to stimulation (number of mature oocytes: 7.6±4.3 vs. 14.5±7.7 in control group, p = 0.006) despite the highest total administered FSH dose (2480±880 IU vs. 1831±460 IU in control group, p = 0.02). Dysregulation of the cholesterol biosynthesis pathway is observed in the breast cancer group. For TNBC and HR+ cancer patients, we observed an increase in the transcripts levels of CYP51 enzyme (respectively 3.28±1.69 vs. 1.84±2.33, p = 0.0098 and 1.77±1.78 vs. 1.84±2.33, p = 0.03) and SREBP2 activator (respectively 2.04±0.95 vs. 1.27±1.13, p = 0.003 and 1.12±0.47 vs. 1.27±1.13, p = 0.02) of the cholesterol biosynthesis pathway compared to the control group. In HER2+ cancer patients, a significant decrease in the expression levels of SQLE (0.39±0.34 vs 1.81±3.99, p = 0.001) and DHRC7 enzymes (0.33±0.32 vs 1.21±0.88, p = 0.0002) is observed compared to the control group. Limitations, reasons for caution Our preliminary results should be confirmed with the analysis of a larger number of participants. We should confirm that the observed modulations in the expression levels of enzymes and regulators of the cholesterol biosynthesis pathway led to a loss of cholesterol homeostasis by quantifying cholesterol in FF. Wider implications of the findings Our findings strengthen the hypothesis that cancer exerts a deleterious impact on the ovarian functions, as we observed a lower ovarian response in patients with breast cancer. This project will have clinical implications, such as to adapt the fertility preservation approach according to the breast cancer subtype. Trial registration number Not applicable

Dysregulated expression of cholesterol biosynthetic genes in Alzheimer's disease alters epigenomic signatures of hippocampal neurons

Aging is the main risk factor of cognitive neurodegenerative diseases such as Alzheimer's disease, with epigenome alterations as a contributing factor. Here, we compared transcriptomic/epigenomic changes in the hippocampus, modified by aging and by tauopathy, an AD-related feature. We show that the cholesterol biosynthesis pathway is severely impaired in hippocampal neurons of tauopathic but not of aged mice pointing to vulnerability of these neurons in the disease. At the epigenomic level, histone hyperacetylation was observed at neuronal enhancers associated with glutamatergic regulations only in the tauopathy. Lastly, a treatment of tau mice with the CSP-TTK21 epi-drug that restored expression of key cholesterol biosynthesis genes counteracted hyperacetylation at neuronal enhancers and restored object memory. As acetyl-CoA is the primary substrate of both pathways, these data suggest that the rate of the cholesterol biosynthesis in hippocampal neurons may trigger epigenetic-driven changes, that may compromise the functions of hippocampal neurons in pathological conditions.

Abstract A026: PIN1 isomerase promotes the initiation and progression of bladder cancer through SREBP2-mediated cholesterol biosynthesis pathway

Abstract Bladder cancer, one of the most commonly diagnosed cancers worldwide, is associated with high morbidity, mortality, and a poor prognosis. The PIN1 phospho-dependent prolyl isomerase is frequently overexpressed in many human cancer types and affects tumor initiation and progression through disrupting the balance of oncoprotein and tumor suppressor protein signaling. However, the functional pSer/Thr.Pro protein substrates of PIN1 and its effects on downstream signaling in bladder carcinogenesis remain largely unknown. Phenotypically, we discovered that ablation of Pin1 in human/mouse bladder cancer cells and organoids formed from mouse primary urothelial cells resulted in decreased cell proliferation, stemness maintenance, cell invasion, migration, urothelium clearance capacity, and reduced free/total cholesterol levels in vitro. Re-expressing Pin1 in Pin1 knockout cells reversed the defects caused by lack of Pin1. Moreover, in vivo subcutaneous xenograft and allograft transplantation mouse models combined with an orthotopic implantation model were utilized to confirm a positive role for Pin1 in controlling tumor growth and potential metastasis. Therapeutically, a combination of the sulfopin PIN1 inhibitor and the simvastatin HMGCR inhibitor was shown to suppress cell proliferation in vitro and tumor growth in vivo synergistically. Mechanistically, we observed a negative enrichment of SREBP2-driven cholesterol metabolism pathways in PIN1 knockout cells via RNA-sequencing and used a suite of diverse molecular and biochemical approaches to show that PIN1 directly binds to JNK-dependent phosphorylated SREBP2 (Ser455) and vice versa. These results indicate that active cholesterol biosynthesis pathway in bladder cancer cells is regulated by PIN1-mediated isomerization and JNK-mediated phosphorylation of its key transcriptional factor SREBP2. These findings emphasize that PIN1 can act as a regulator and potential therapeutic target in bladder cancer. Citation Format: Xue Wang, Tony Hunter. PIN1 isomerase promotes the initiation and progression of bladder cancer through SREBP2-mediated cholesterol biosynthesis pathway [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr A026.

AN OVERVIEW OF SOME HERBAL ANTIDEPRESSANT PLANTS

There are numerous ways to categorize and treat depression, which is a diverse mood disease. The illness is caused by factors such as 5-HT, NA, and MAO-A inhibition and stimulation. Reduced curiosity about pleasure, feelings of inappropriate guilt or worthlessness, a drop in hunger and sexual desire, sleeplessness, and persistent suicidal thoughts are some of the symptoms. There are several synthetic medications used to treat depression, but not all of them make patients happy, and some of them may have negative side effects. Many have turned to well-liked traditional herbal remedies to avoid the negative effects of allopathic therapy. Due to their broad application, therapeutic efficacy, and little to negligible adverse effects, herbal medications are currently used worldwide. Several medicinal plants and medicines derived from these plants have shown antidepressant properties by the combined effect of their medicinal constituents. We discuss promising novel medicinal products targets for the management of major depressive illness in this review. We address the potential antidepressant benefits of selectively targeting receptors, including opioid, G-protein-coupled, and metabotropic glutamate receptors. Since they may also have therapeutic value, we also talk about substances that target biological processes, including inflammation, the gut microbiota, the cholesterol biosynthesis pathway, and the hypothalamic-pituitary-adrenal axis. Lastly, we offer a synopsis of all the plants displayed in graphical format, together with an overview of the antidepressant plants which currently are widely accessible.

A Review of Therapeutic Options for Linear Porokeratosis

Linear porokeratosis (LP) is a rare and uncommon variant of porokeratosis presenting as linear annular papules or plaques along Blaschko’s lines. It may arise spontaneously, although evidence of genetic predisposition exists via point mutations in the mevalonate pathway of cholesterol biosynthesis. Malignant transformation is the most serious complication of this chronic, progressive dyskeratosis. We review the currently available treatment options for LP, including topical, systemic, laser, photodynamic, and surgical therapies.

Early statin exposure influences cardiac and skeletal development with implications for ion channel transcriptomes in zebrafish

Statins, widely prescribed for cholesterol management by inhibiting HMG-CoA reductase in the cholesterol biosynthesis pathway, may also influence vertebrate development. In this study, we investigated the developmental effects of two widely used statins, atorvastatin (ATO) and pravastatin (PRA), on zebrafish offspring. For ATO, we administered doses classified as low (1 μM), medium (5 μM), and high (10 μM), while for PRA, the corresponding concentrations were set at low (18 μM), medium (180 μM), and high (270 μM). Our results showed significant reductions in birth and hatching rates, along with decreased body length in offspring at all ATO concentrations and medium to high PRA concentrations. A notable increase in malformation rates, especially in the spine and heart, was observed across all ATO treatments and in medium and high PRA groups. Additionally, we observed reduced heart contraction rates, decreased heart size, lower bone volumes, and diminished expression of mRNA osteogenic markers. Elevated venous sinus-artery bulb (SV-BA) ratios, increased thoracic area, and abnormal cartilage development were also prominent in all ATO-treated groups. Transcriptome analysis revealed alterations in genes predominantly associated with ion channels. These findings provide insights into the potential impacts of specific concentrations of statins on offspring development and highlight potential gene interactions with statins.

Abstract 5873: ERα coordinates with squalene synthase to confer statin resistance in lung cancer

Abstract Statins are widely used to treat hypercholesterolemia by inhibiting hydroxymethylglutaryl coenzyme A reductase (HMGCR). Accumulating evidence suggests that statins also have protective effects against cancer recurrence. However, the role of statins in preventing lung cancer and biomarkers for predicting statin treatment response remains lacking. This study analyzes molecular features that dictate statin sensitivity in lung cancer by correlating large-scale statin sensitivity data and basal gene expression in a collection of 125 lung cancer patients. We identified a gene signature associated with lovastatin sensitivity and showed that gene expression in mesenchymal molecular features, the cholesterol biosynthesis pathway, and estrogen receptor alpha (ERα) signaling were key determinants of lovastatin sensitivity in lung cancer cells. To this end, we further discovered that overexpression of a committed step enzyme in cholesterol biosynthesis farnesyl-diphosphate farnesyltransferase 1 (FDFT1), also known as squalene synthase (SQS), is capable of activating ERα and is associated with increased statin tolerance. In clinical specimens, overexpression of SQS positively correlated with nuclear expression of ERα in lung cancer patients, and the combination of SQS and ERα is a powerful prognostic predictor for lung cancer. Activation of the SQS-ERα signaling axis and epithelial-to-mesenchymal transition (EMT) status represents two important features in determining statin sensitivity in lung cancer. Keywords: Statin, cholesterol biosynthesis, squalene synthase, estrogen receptor α, Epithelial-mesenchymal transition Citation Format: Yi-Fang Yang. ERα coordinates with squalene synthase to confer statin resistance in lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5873.

Abstract 4737: The combination of the BET inhibitor JQ1 and gemcitabine induces regressions in gemcitabine resistant patient-derived xenograft models of pancreatic cancer

Abstract Efforts to develop targeted therapies for drug resistant tumors have been relatively unsuccessful. The 5-year survival for patients with advanced pancreatic cancer is ~3%. Gemcitabine is usually combined with nab-paclitaxel as a standard of care for treatment of locally advanced or metastatic pancreatic ductal adenocarcinoma (PDAC). However, no chemotherapeutic regimens thus far evaluated have been curative. We developed the first PDAC patient-derived xenograft (PDX) models in which resistance against gemcitabine was acquired in vivo. We used RNA-seq and ingenuity pathway analysis to compare expression profiles of paired parent vs gemcitabine resistant PDX models. This comparison suggested a previously unreported mechanism for gemcitabine resistance, involving aberrations of cholesterol biosynthesis and lipid metabolism pathways. We also made the unexpected observation that gemcitabine-resistant PDAC models derived from primary tumors have high levels of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), an enzyme essential to cholesterol biosynthesis and rate limiting in ketogenesis. Notably, the BET bromodomain inhibitor JQ1 decreases HMGCS2 levels; and BET inhibitors + gemcitabine exert synergistic cytotoxicity in gemcitabine-resistant PDAC cells. We determined that the BET bromodomain inhibitor JQ1 + gemcitabine induces regressions of two in vivo gemcitabine-resistant tumor models which we developed directly from primary human tumor tissue. These mechanism-based studies suggest that inhibiting HMGCS2 represents a novel approach to therapy for PDAC. We propose that combining gemcitabine with agents that decrease levels of HMGCS2 comprises effective treatment for patients with drug resistant PDAC. Citation Format: Aubrey L. Miller, Samuel C. Fehling, Eric Josh Brown, Eric O. Heard, Tracy L. Gamblin, Rebecca B. Vance, Karina J. Yoon. The combination of the BET inhibitor JQ1 and gemcitabine induces regressions in gemcitabine resistant patient-derived xenograft models of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4737.

Platycodi Radix Extract Prevents Hepatic Steatosis by Enhancing Bile Acid Synthesis in a High-Fat Diet-Induced Fatty Liver Mouse Model.

We aimed to identify the mechanism underlying the preventive effects of non-alcoholic fatty liver disease (NAFLD) through Platycodi Radix consumption using liver proteomic and bioinformatic analysis. C57BL/6J mice were categorized into three groups: those receiving a standard chow diet (NCD), those on a high-fat diet (HFD), and those on an HFD supplemented with 5% Platycodi Radix extract (PRE). After a 12-week period, PRE-fed mice exhibited a noteworthy prevention of hepatic steatosis. Protein identification and quantification in liver samples were conducted using LC-MS/MS. The identified proteins were analyzed through Ingenuity Pathway Analysis software, revealing a decrease in proteins associated with FXR/RXR activation and a concurrent increase in cholesterol biosynthesis proteins in the PRE-treated mouse liver. Subsequent network analysis predicted enhanced bile acid synthesis from these proteins. Indeed, the quantity of bile acids, which was reduced in HFD conditions, increased in the PRE group, accompanied by an elevation in the expression of synthesis-related proteins. Our findings suggest that the beneficial effects of PRE in preventing hepatic steatosis may be mediated, at least in part, through the modulation of FXR/RXR activation, cholesterol biosynthesis, and bile acid synthesis pathways.

Discovery and Optimization of Selective Brain-Penetrant EBP Inhibitors that Enhance Oligodendrocyte Formation.

The inhibition of emopamil binding protein (EBP), a sterol isomerase within the cholesterol biosynthesis pathway, promotes oligodendrocyte formation, which has been proposed as a potential therapeutic approach for treating multiple sclerosis. Herein, we describe the discovery and optimization of brain-penetrant, orally bioavailable inhibitors of EBP. A structure-based drug design approach from literature compound 1 led to the discovery of a hydantoin-based scaffold, which provided balanced physicochemical properties and potency and an improved in vitro safety profile. The long half-lives of early hydantoin-based EBP inhibitors in rodents prompted an unconventional optimization strategy, focused on increasing metabolic turnover while maintaining potency and a brain-penetrant profile. The resulting EBP inhibitor 11 demonstrated strong in vivo target engagement in the brain, as illustrated by the accumulation of EBP substrate zymostenol after repeated dosing. Furthermore, compound 11 enhanced the formation of oligodendrocytes in human cortical organoids, providing additional support for our therapeutic hypothesis.

Effects of bempedoic acid on markers of inflammation and Lp(a).

To study the effect of bempedoic acid on markers of inflammation and lipoprotein (a) to help determine if the drug would be useful to treat patients with elevated cardiovascular risks and residual cardiovascular risk despite optimal low-density lipoprotein cholesterol (LDL-C) levels. Bempedoic acid is found to cause significant reduction in LDL-C and high-sensitivity C-reactive protein (hs-CRP) in various randomized clinical trials. Multiple meta-analyses have also found that bempedoic acid therapy leads to reduction in non-high-density lipoprotein cholesterol (non-HDL-C), total cholesterol (TC) and apolipoprotein B (ApoB) levels. However, it has minimal effect on lipoprotein (a) (Lp(a)) level. Bempedoic acid is a new lipid-lowering agent that inhibits enzyme ATP-citrate lyase in the cholesterol biosynthesis pathway. Major risk of cardiovascular events and its associated morbidity and mortality are proportional to LDL-C and inflammatory markers levels. It was found that bempedoic acid significantly lowers LDL-C, hs-CRP and other inflammatory markers levels. This drug could potentially be used in patients with elevated cardiovascular risk, in patients with residual cardiovascular risk despite attaining LDL-C goal and in statin intolerant patients.

THE EFFECTS OF ROSUVASTATIN EFFECT ON THE KIDNEY IN MALE ALBINO RATS

Background and Aim: Rosuvastatin is known to competitively inhibit HMG-CoA reductase, selectively and reversibly, this enzyme converts HMG-CoA to mevalonic acid in the cholesterol biosynthesis pathway, which is the rate-limiting step in cholesterol synthesis. Rosuvastatin is one of the most important cholesterol-lowering stanins that has been on the market by AstraZeneca since 2003, with unique pharmacokinetic and pharmacodynamic properties. There are some studies that dealt with the effect of rosuvastatin on the kidneys and were contradictory in their results. Therefore, the aim of the current study was to evaluate the effect of rosuvastatin (pharma science Incorporated company - Montreal/ Canada) on the physiological and histopathological parameters in the kidneys of male albino rats. Material and Methods: Forty adult of albino rats were used in the study. After acclimation, the rats were randomly divided into four groups (8 rats in each group) as follows: The first control group: was given normal saline solution (NS), the second group 10 mg/kg rosuvastatin, the third group was given 20 mg/kg rosuvastatin, while the fourth group was given 40 mg/kg rosuvastatin. The dose was continued for 60 days in a once-daily dosing regimen. After the end of the experiment, chemical analyzes were performed for kidney function, including cystatin C and vitamin D3. Then the rats were dissected, and kidney tissues were taken for histological study

Effects of multi-walled carbon nanotubes on gene and microRNA expression in human hepatocarcinoma HepG2 cells.

The usage of multi-walled carbon nanotubes (MWCNT) has increased exponentially in the past years, but, potential toxicity mechanisms are not clear. We studied the transcriptomic alterations induced by one multi-walled carbon nanotube (MWCNT) and its -OH and -COOH functionalized derivatives in human HepG2 cells. We showed that all three MWCNT treatments induced alterations in stress-related signaling pathways, inflammation-related signaling pathways, cholesterol synthesis pathways, proliferation-related pathways, senescence-related pathways and cancer-related pathways. In stress-related pathways, the acute phase response was induced in all three MWCNTs and all doses treated and ranked high. Other stress-related pathways were also related to the oxidative-induced signaling pathways, such as NRF-2 mediated oxidative stress response, hepatic fibrosis/Stella cell activation, iNOS signaling, and Hif1α signaling. Many inflammation-related pathways were altered, such as IL-8, IL-6, TNFR1, TNFR2, and NF-κB signaling pathways. These results were consistent with our previous results with exposures to the same three multi-walled carbon nanotubes in human lung BEAS-2B and also with results in mice and rats. From the microRNA target filter analysis, TXNIP & miR-128-3p interaction was present in all three MWCNT treatments, and maybe important for the induction of oxidative stress. CXCL-8 & miR-146-5p and Wee1 & miR-128-3p were only present in the cells treated with the parent and the OH-functionalized MWCNTs. These mRNA-miRNA interactions were involved in oxidative stress, inflammation, cell cycle, cholesterol biosynthesis and cancer related pathways. Target filter analysis also showed altered liver hyperplasia/hyperproliferation and hepatic cancer pathways. In short, target filter analysis complemented the transcriptomic analysis and pointed to specific gene/microRNA interactions that can help inform mechanism of action. Moreover, our study showed that the signaling pathways altered in HepG2 cells correlated well with the toxicity and carcinogenicity observed in vivo, indicating that HepG2 may be a good in vitro predictive model for MWCNT toxicity studies.

Cystatin from the helminth Ascaris lumbricoides upregulates mevalonate and cholesterol biosynthesis pathways and immunomodulatory genes in human monocyte-derived dendritic cells.

Ascaris lumbricoides cystatin (Al-CPI) prevents the development of allergic airway inflammation and dextran-induced colitis in mice models. It has been suggested that helminth-derived cystatins inhibit cathepsins in dendritic cells (DC), but their immunomodulatory mechanisms are unclear. We aimed to analyze the transcriptional profile of human monocyte-derived DC (moDC) upon stimulation with Al-CPI to elucidate target genes and pathways of parasite immunomodulation. moDC were generated from peripheral blood monocytes from six healthy human donors of Denmark, stimulated with 1 µM of Al-CPI, and cultured for 5 hours at 37°C. RNA was sequenced using TrueSeq RNA libraries and the NextSeq 550 v2.5 (75 cycles) sequencing kit (Illumina, Inc). After QC, reads were aligned to the human GRCh38 genome using Spliced Transcripts Alignment to a Reference (STAR) software. Differential expression was calculated by DESEq2 and expressed in fold changes (FC). Cell surface markers and cytokine production by moDC were evaluated by flow cytometry. Compared to unstimulated cells, Al-CPI stimulated moDC showed differential expression of 444 transcripts (|FC| ≥1.3). The top significant differences were in Kruppel-like factor 10 (KLF10, FC 3.3, PBH = 3 x 10-136), palladin (FC 2, PBH = 3 x 10-41), and the low-density lipoprotein receptor (LDLR, FC 2.6, PBH = 5 x 10-41). Upregulated genes were enriched in regulation of cholesterol biosynthesis by sterol regulatory element-binding proteins (SREBP) signaling pathways and immune pathways. Several genes in the cholesterol biosynthetic pathway showed significantly increased expression upon Al-CPI stimulation, even in the presence of lipopolysaccharide (LPS). Regarding the pathway of negative regulation of immune response, we found a significant decrease in the cell surface expression of CD86, HLA-DR, and PD-L1 upon stimulation with 1 µM Al-CPI. Al-CPI modifies the transcriptome of moDC, increasing several transcripts encoding enzymes involved in cholesterol biosynthesis and SREBP signaling. Moreover, Al-CPI target several transcripts in the TNF-alpha signaling pathway influencing cytokine release by moDC. In addition, mRNA levels of genes encoding KLF10 and other members of the TGF beta and the IL-10 families were also modified by Al-CPI stimulation. The regulation of the mevalonate pathway and cholesterol biosynthesis suggests new mechanisms involved in DC responses to helminth immunomodulatory molecules.

Environmentally relevant concentrations of aqueous atorvastatin produce alterations in cholesterol biosynthesis and gene expression patterns in Xenopus laevis

Numerous studies report active pharmaceutical compounds detected in both wastewater effluent and surface waters. Exposure to statin drugs in general, and atorvastatin in particular, is likely to be a concern. We hypothesized that chronic exposure to low concentrations of atorvastatin in water would result in an adverse effect on production of steroids regulating growth and development of the model amphibian Xenopus laevis. The FETAX assay was used to evaluate the effects of a range of doses of atorvastatin on developing embryos. A 60 day metamorphosis assay assessed the effects of aqueous atorvastatin exposure at environmentally concentrations on metamorphosing tadpoles. A 60 day chronic flow-through exposure evaluated the effects of chronic low concentrations of atorvastatin on adults.The purpose of the FETAX assay was to confirm that atorvastatin can reduce circulating cholesterol in X. laevis with a similar manner to that expected in humans. The results of the 60-day flow-through exposure on metamorphosing tadpoles showed significant evidence of altered cholesterol biosynthesis. The dose-dependent increase in cyp19a1 expression also indicated that the steroidogenesis pathway was affected. The RNAseq analysis confirmed that exposure to environmentally relevant concentrations of atorvastatin does cause significant alterations to global transcriptional profiles in a manner consistent with dysregulation of the cholesterol biosynthesis pathway, both through the downregulation of many genes involved in that pathway, but also in the impacts to other, related pathways. The qPCR data for both adult males and adult females indicated only slight changes in expression with the exception that hmgcr was significantly downregulated in males, and cyp3a4 expression was significantly downregulated in females. The data we present here indicated that chronic exposure to environmentally relevant concentrations of atorvastatin does have the potential to impact early life stage frogs, particularly by altering expression of genes involved in critical molecular pathways.

The cholesterol biosynthesis enzyme FAXDC2 couples Wnt/β-catenin to RTK/MAPK signaling.

Wnts, cholesterol, and MAPK signaling are essential for development and adult homeostasis. Here, we report that fatty acid hydroxylase domain containing 2 (FAXDC2), a previously uncharacterized enzyme, functions as a methyl sterol oxidase catalyzing C4 demethylation in the Kandutsch-Russell branch of the cholesterol biosynthesis pathway. FAXDC2, a paralog of MSMO1, regulated the abundance of the specific C4-methyl sterols lophenol and dihydro-T-MAS. Highlighting its clinical relevance, FAXDC2 was repressed in Wnt/β-catenin-high cancer xenografts, in a mouse genetic model of Wnt activation, and in human colorectal cancers. Moreover, in primary human colorectal cancers, the sterol lophenol, regulated by FAXDC2, accumulated in the cancerous tissues and not in adjacent normal tissues. FAXDC2 linked Wnts to RTK/MAPK signaling. Wnt inhibition drove increased recycling of RTKs and activation of the MAPK pathway, and this required FAXDC2. Blocking Wnt signaling in Wnt-high cancers caused both differentiation and senescence; and this was prevented by knockout of FAXDC2. Our data show the integration of 3 ancient pathways, Wnts, cholesterol synthesis, and RTK/MAPK signaling, in cellular proliferation and differentiation.

Distinctive genes and signaling pathways associated with type 2 diabetes-related periodontitis: Preliminary study.

The biological mechanisms underlying the pathogenesis of type 2 diabetes (T2DM)-related periodontitis remain unclear. This cross-sectional study evaluated the distinctive transcriptomic changes between tissues with periodontal health and with periodontitis in patients with T2DM. In this cross-sectional study, whole transcriptome sequencing was performed on gingival biopsies from non-periodontitis and periodontitis tissues from non-diabetic and diabetic patients. A differentially expressed gene (DEG) analysis and Ingenuity Pathway Analysis (IPA) assessed the genes and signaling pathways associated with T2DM-related periodontitis. Immunohistochemistry was performed to validate selected DEGs possibly involved in T2DM-related periodontitis. Four hundred and twenty and one thousand five hundred and sixty-three DEGs (fold change ≥ 2) were uniquely identified in the diseased tissues of non-diabetic and diabetic patients, respectively. The IPA predicted the activation of Phagosome Formation, Cardiac β-adrenergic, tRNA Splicing, and PI3K/AKT pathways. The IPA also predicted the inhibition of Cholesterol Biosynthesis, Adrenomedullin, and Inositol Phosphate Compounds pathways in T2DM-related periodontitis. Validation of DEGs confirmed changes in protein expression of PTPN2, PTPN13, DHCR24, PIK3R2, CALCRL, IL1RN, IL-6R and ITGA4 in diseased tissues in diabetic subjects. Thus, these preliminary findings indicate that there are specific genes and functional pathways that may be involved in the pathogenesis of T2DM-related periodontitis.