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The activation of pregnane X receptor (PXR) or peroxisome proliferator-activated receptor α (PPARα) can induce liver enlargement. Recently, we reported that PXR or PPARα activation-induced hepatomegaly depends on yes-associated protein (YAP) signaling and is characterized by hepatocyte hypertrophy around the central vein area and hepatocyte proliferation around the portal vein area. However, it remains unclear whether PXR or PPARα activation-induced hepatomegaly can be reversed after the withdrawal of their agonists. In this study, we investigated the regression of enlarged liver to normal size following the withdrawal of PCN or WY-14643 (typical agonists of mouse PXR or PPARα) in C57BL/6 mice. The immunohistochemistry analysis of CTNNB1 and KI67 showed a reversal of hepatocyte size and a decrease in hepatocyte proliferation after the withdrawal of agonists. In details, the expression of PXR or PPARα downstream proteins (CYP3A11, CYP2B10, ACOX1, and CYP4A) and the expression of proliferation-related proteins (CCNA1, CCND1, and PCNA) returned to the normal levels. Furthermore, YAP and its downstream proteins (CTGF, CYR61, and ANKRD1) also restored to the normal states, which was consistent with the change in liver size. These findings demonstrate the reversibility of PXR or PPARα activation-induced hepatomegaly and provide new data for the safety of PXR and PPARα as drug targets. • PXR or PPARα activation-induced hepatomegaly is reversible. • The hepatocyte size and proliferation return to normal state after the reversal. • Protein levels altered by PXR or PPARα activation are restored after the reversal. [ABSTRACT FROM AUTHOR]

Introduction: As a devastating neurological disease, spinal cord injury (SCI) results in severe tissue loss and neurological dysfunction. Pregnane X receptor (PXR) is a ligand‐activated nuclear receptor with a major regulatory role in xenobiotic and endobiotic metabolism and recently has been implicated in the central nervous system. In the present study, we aimed to investigate the role and mechanism of PXR in SCI. Methods: The clip‐compressive SCI model was performed in male wild‐type C57BL/6 (PXR+/+) and PXR‐knockout (PXR−/−) mice. The N2a H2O2‐induced injury model mimicked the pathological process of SCI in vitro. Pregnenolone 16α‐carbonitrile (PCN), a mouse‐specific PXR agonist, was used to activate PXR in vivo and in vitro. The siRNA was applied to knock down the PXR expression in vitro. Transcriptome sequencing analysis was performed to discover the relevant mechanism, and the NRF2 inhibitor ML385 was used to validate the involvement of PXR in influencing the NRF2/HO‐1 pathway in the SCI process. Results: The expression of PXR decreased after SCI and reached a minimum on the third day. In vivo, PXR knockout significantly improved the motor function of mice after SCI, meanwhile, inhibited apoptosis, inflammation, and oxidative stress induced by SCI. On the contrary, activation of PXR by PCN negatively influenced the recovery of SCI. Mechanistically, transcriptome sequencing analysis revealed that PXR activation downregulated the mRNA level of heme oxygenase‐1 (HO‐1) after SCI. We further verified that PXR deficiency activated the NRF2/HO‐1 pathway and PXR activation inhibited this pathway in vitro. Conclusion: PXR is involved in the recovery of motor function after SCI by regulating NRF2/HO‐1 pathway. [ABSTRACT FROM AUTHOR]

Background and aims: The herbal supplement Gancao, also known as licorice, belongs to the genus Glycyrrhiza and has been used worldwide for its hepatoprotective effect. Recent studies have raised concerns about potential herb-drug interactions associated with Gancao via pregnane X receptor (PXR)-mediated induction of hepatic cytochrome P450 3A4 (CYP3A4). The current work aimed to determine the phytochemicals in Gancao that activate PXR and induce CYP3A4. Methods: DPX2 cells were used for cell-based PXR reporter assays. The phytochemicals in Gancao extract were identified using a metabolomics approach. The effects of PXR activators identified from in vitro studies were further investigated in PXR- and CYP3A4-humanized mouse models. Results: Gancao was verified to be a PXR-activating herb. Two major phytochemicals in Gancao, glycyrrhizin (GZ) and glycyrrhetinic acid (GA), did not activate PXR in the cell-based reporter assays. However, glabridin was shown to activate PXR in a dose-dependent manner. In vivo studies confirmed that GZ is not a PXR activator and glabridin is a weak PXR activator. Although GA did not active PXR in vitro, it induced CYP3A4 expression in a PXR-dependent manner in the PXR- and CYP3A4-humanized mice. Conclusions: GZ is not a PXR activator. GA could not activate PXR in cell-based reporter assays but it could activate PXR in vivo. Glabridin is a weak PXR activator. This work provides novel insights into the underlying mechanisms of Gancao-related herb-drug interactions via PXR.

[Display omitted] Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Pregnane X receptor (PXR), a xenobiotic-sensing nuclear receptor, plays a critical role in the metabolism of endogenous and exogenous substances in the liver. Here, we investigate whether PXR plays a role in pathogenesis of HCC. We show that liver tumors were developed in diethylnitrosamine (DEN)-treated in PXR knockout (KO) mice. Hepatic levels of prostaglandin F 2α (PGF 2α) and aldo–keto reductase family 1 member C18 (Akr1c18), a prostaglandin synthase of catalyzing reduction of PGH 2 to PGF 2α , were significantly elevated in DEN-treated PXR KO mice. Hepatic mRNA levels of alpha fetoprotein (AFP), cyclin D1 (Ccnd1), fibroblast growth factor 21 (FGF21), and inflammatory cytokine interleukin 6 (IL-6) were significantly increased in DEN-treated PXR KO mice. Other members of Akr1c family, liver metabolizing enzymes including Cyp1a2, Cyp2b10 and Cyp3a11, and bile acid synthesis enzyme Cyp7a1 mRNA levels were significantly decreased in DEN-treated PXR KO mice. Our findings revealed that PXR deficiency promoted DEN-induced HCC in mice via induction of Akr1c18 expression and PGF 2α levels and the increased PGF 2α levels synthetized by Akr1c18 enhanced hepatocytes proliferation and induced inflammatory cytokine production, which accelerated liver tumor development after DEN treatment, suggesting that PXR deficiency may create a microenvironment that is more prone to DEN-induced liver tumors and targeting PXR and Akr1c18 to reduce PGF 2α biosynthesis may be a potential and novel therapeutic strategy for HCC. [ABSTRACT FROM AUTHOR]

As a member of the nuclear receptor (NR) superfamily, pregnane X receptor (PXR; NR1I2) is a ligand-activated transcription factor that plays a crucial role in the metabolism of xenobiotics and endobiotics in mammals. The tissue distribution of PXR is parallel to its function with high expression in the liver and small intestine and moderate expression in the kidney, stomach, skin, and blood-brain barrier, which are organs and tissues in frequent contact with xenobiotics. PXR was first recognized as an exogenous substance receptor regulating metabolizing enzymes and transporters and functioning in detoxification and drug metabolism in the liver. However, further research revealed that PXR acts as an equally important endogenous substance receptor in the metabolism and homeostasis of endogenous substances. In this review, we summarized the functions of PXR in metabolism of different substances such as glucose, lipid, bile acid, vitamin, minerals, and endocrines, and also included insights of the application of PXR ligands (drugs) in specific diseases. [ABSTRACT FROM AUTHOR]

Leydig cells (LCs) in the testes produce the male sex hormone testosterone (T). Several xenobiotics, including clinical drugs, supplements, and environmental chemicals, are known to disrupt T homeostasis. Notably, some of these xenobiotics are known to activate the pregnane X receptor (PXR), a ligand-dependent nuclear receptor. However, it is currently unknown whether PXR is expressed in LCs and whether PXR activation alters T synthesis in rodent LCs. Therefore, in this study, we sought to determine whether PXR is expressed in rodent LCs and whether pregnenolone 16-alpha carbonitrile (PCN), the prototype agonist of rodent PXR, regulates T biosynthesis in rodent LCs. Hormonal as well as protein and gene expression analyses were conducted in rat primary LCs and MA-10 mouse Leydig cells. Results showed that PXR was expressed at the mRNA and protein level in both rat primary LCs and MA-10 cells. Incubation of rat primary LCs with PCN resulted in a significant decrease in T secretion. This PCN-induced decrease in T secretion was associated with decreased protein expression of key steroidogenic enzymes such as 3β-HSD and CYP17A1. RNA-seq results from MA-10 cells showed that PCN down-regulated the transcripts of steroidogenic enzymes and proteins involved in the T synthesis pathway. Together, these results suggest that PCN, an agonist of rodent PXR, can regulate T biosynthesis in rodent LCs by down-regulating the expression of the steroidogenic enzymes involved in T biosynthesis. Our results are significant as they provide a potential novel mechanism for disruption of testosterone homeostasis by a variety of xenobiotics.

Non-alcoholic fatty liver disease (NAFLD) has become the leading cause of chronic liver disease in adults and children worldwide. The symptoms of NAFLD range from simple steatosis and non-alcoholic steatohepatitis (NASH) to hepatic fibrosis or cirrhosis, even ultimately develops to hepatocellular carcinoma. Nuclear receptors (NRs) are a superfamily of ligand-activated transcription factors, most of which are ligand-activated that control cellular homeostasis in the liver and other tissues. A growing number of studies demonstrated the important role of NRs in NAFLD. In this review, the current findings on the role of NRs in NAFLD are summarized and future perspectives to target NRs for NAFLD are discussed.

Pregnane X receptor (PXR), extensively expressed in human tissues related to digestion and metabolism, is responsible for recognizing and detoxifying diverse xenobiotics encountered by humans. To comprehend the promiscuous nature of PXR and its ability to bind a variety of ligands, computational approaches, viz., quantitative structure-activity relationship (QSAR) models, aid in the rapid dereplication of potential toxicological agents and mitigate the number of animals used to establish a meaningful regulatory decision. Recent advancements in machine learning techniques accommodating larger datasets are expected to aid in developing effective predictive models for complex mixtures (viz., dietary supplements) before undertaking in-depth experiments. Five hundred structurally diverse PXR ligands were used to develop traditional two-dimensional (2D) QSAR, machine-learning-based 2D-QSAR, field-based three-dimensional (3D) QSAR, and machine-learning-based 3D-QSAR models to establish the utility of predictive machine learning methods. Additionally, the applicability domain of the agonists was established to ensure the generation of robust QSAR models. A prediction set of dietary PXR agonists was used to externally-validate generated QSAR models. QSAR data analysis revealed that machine-learning 3D-QSAR techniques were more accurate in predicting the activity of external terpenes with an external validation squared correlation coefficient ( R 2 ) of 0.70 versus an R 2 of 0.52 in machine-learning 2D-QSAR. Additionally, a visual summary of the binding pocket of PXR was assembled from the field 3D-QSAR models. By developing multiple QSAR models in this study, a robust groundwork for assessing PXR agonism from various chemical backbones has been established in anticipation of the identification of potential causative agents in complex mixtures.

The incidence of nonalcoholic fatty liver disease (NAFLD) has been rising worldwide in parallel with diabetes and metabolic syndrome. NAFLD refers to a spectrum of liver abnormalities with a variable course, ranging from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH), eventually leading to cirrhosis and hepatocellular carcinoma. Pregnane X receptor (PXR), a member of the nuclear receptor superfamily, plays a prominent part in the regulation of endogenous metabolic genes in NAFLD. Recent studies have suggested that PXR has therapeutic potential for NAFLD, yet the relationship between PXR and NAFLD remains controversial. In this review, PXR is proposed to play a dual role in the development and progression of NAFLD. Its activation will aggravate steatosis of the liver, reduce inflammatory response, and prevent liver fibrosis. In addition, the interactions between PXR, substance metabolism, inflammation, fibrosis, and gut microbiota in non-alcoholic fatty liver were elucidated. Due to limited therapeutic options, a better understanding of the contribution of PXR to the pathogenesis of NAFLD should facilitate the design of innovative drugs targeting NAFLD., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Pregnane X receptor (PXR) is a member of nuclear receptor superfamily and responsible for the detoxification of xenobiotics. Recent studies demonstrated that PXR was also expressed in the vasculature and protected the vessels from endogenous and exogenous insults, thus representing a novel gatekeeper in vascular defense. In this study, we examined the potential function of PXR in the neointimal formation following vascular injury. In the rat carotid artery after balloon injury, overexpression of a constitutively active PXR increased the intima‐to‐media ratio in the injured region. PXR increased cell proliferation and migration in cultured rat aortic smooth muscle cells (SMCs) by inducing the expressions of cyclins (cyclin A, D1, and E) and cyclin‐dependent kinase 2. In addition, PXR increased the phosphorylation and activation of extracellular‐signal‐regulated kinase 1/2 (ERK1/2) and p38 mitogen‐activated protein kinase (MAPK). Inactivation of ERK1/2 and p38 MAPK pathways using selective inhibitors (U0126 and SB203580) abrogated PXR‐induced SMC proliferation and migration. Furthermore, cigarette smoke particles (CSP) activated PXR in SMCs. Knockdown of PXR by small interfering RNA suppressed the cell proliferation, migration, and activation of the MAPK pathways by CSP. These findings suggested a novel role for PXR in promoting SMC proliferation and migration, and neointimal hyperplasia. Therefore, PXR may be a potential therapeutic target for vascular disease related to xenobiotics such as cigarette smoking and other environmental pollutants. Our findings suggested a novel role for pregnane X receptor (PXR) in promoting smooth muscle cell (SMC) proliferation and migration, and neointimal hyperplasia. In the rat carotid artery after balloon injury, overexpression of a constitutively active PXR increased the intima‐to‐media ratio in the injured region. PXR increased cell proliferation and migration in cultured rat aortic SMCs. Therefore, PXR may be a potential therapeutic target for vascular disease related to xenobiotics such as cigarette smoking and other environmental pollutants. [ABSTRACT FROM AUTHOR]

Background Tacrolimus, a drug for prevention of rejection after kidney transplantation, has a narrow therapeutic window and is metabolized by the cytochrome P540 3A (CYP3A) system. Tacrolimus exposure increases after steroid tapering in many patients. The pregnane X receptor (PXR)—a mediator for CYP3A —has a steroid receptor and might regulate CYP3A5 activity depending on single nucleotide polymorphisms (SNPs) of CYP3A5 or PXR. This may contribute to differences in tacrolimus exposure after steroid tapering. Methods In a cohort of renal transplant recipients, the influence of CYP3A5 and PXR SNPs (A7635G, C8055T and C25385T) on the dose-normalized Tacrolimus trough concentration (DnC0) and their potential interaction with each other after steroid taper were analysed by linear regression. Eligible were all 83 outpatient renal transplant patients on tacrolimus and steroids in a pharmacokinetic steady state at least 6 weeks after transplantation and whose blood was available for genetic analysis. Results Compared with the CYP3A5*1/*3 genotype, the CYP3A5*3/*3 SNP showed a significantly stronger increase in DnC0 after steroid taper (+0.29 µg/L/mg; P = 0.002). Of the tested PXR SNPs, PXR G7635G individuals had a significantly stronger increase in DnC0 (compared with A7635A, +0.31 µg/L/mg; P = 0.02), with a weaker increase in A7635G heterozygotes (+0.17 µg/L/mg; P = 0.124). There was neither interaction nor association between CYP3A5 and PXR SNPs. Conclusions The magnitude of the DnC0 increase due to steroid taper after renal transplantation is related to CYP3A5 SNPs. Independently, the PXR G7635G SNP is related to this increase, proving the role of PXR in tacrolimus metabolism. [ABSTRACT FROM AUTHOR]

Pregnane X receptor (PXR) is an important member of the nuclear receptor superfamily that copes with various endobiotic and xenobiotic stimuli, such as carcinogens by regulating an array of environmental response genes. Low PXR expression has been shown to promote tumor initiation and metastasis. The aim of the current study was to investigate whether the single nucleotide polymorphisms (SNPs) of PXR could alter lung cancer susceptibility in Chinese by affecting the function or expression of PXR. We genotyped three putatively functional SNPs of PXR (i.e., rs3814055C>T, rs3732360C>T, and rs3814058C>T) and analyzed their associations with lung cancer risk in a two-stage case-control study with a total of 1559 lung cancer cases and 1679 controls in the southern and eastern Chinese population. We found that in comparison to the rs3814058CC common genotype, the rs3814058T variants (TC/TT) which is located in the 3'-untranslated region (3'-UTR) of PXR conferred a consistently increased risk of lung cancer in both the southern Chinese (odd ratios (OR) = 1.24, 95% confidence interval (CI) = 1.03−1.49) and the eastern Chinese (OR = 1.33, 95% CI = 1.02−1.75). The variants also significantly interacted with smoking on increasing cancer risk (p = 0.023). Moreover, lung cancer tissues with the rs3814058T variants showed significantly lower PXR expression than those with rs3814058CC genotype in the smokers (p = 0.041). These results suggested that the rs3814058C>T polymorphism of PXR interacts with smoking on increasing lung cancer risk in Chinese smokers, which might be a functional genetic biomarker for lung cancer.

In recent years many sterols with unusual structures and promising biological profiles have been identified from marine sources. Here we report the isolation of a series of 24-alkylated-hydroxysteroids from the soft coral Sinularia kavarattiensis, acting as pregnane X receptor (PXR) modulators. Starting from this scaffold a number of derivatives were prepared and evaluated for their ability to activate the PXR by assessing transactivation and quantifying gene expression. Our study reveals that ergost-5-en-3β-ol (4) induces PXR transactivation in HepG2 cells and stimulates the expression of the PXR target gene CYP3A4. To shed light on the molecular basis of the interaction between these ligands and PXR, we investigated, through docking simulations, the binding mechanism of the most potent compound of the series, 4, to the PXR. Our findings provide useful functional and structural information to guide further investigations and drug design.

Vitamin K is a fat-soluble vitamin that was originally found as an essential factor for blood coagulation. With the discovery of its role as a co-factor for γ-glutamyl carboxylase (GGCX), its function for blood coagulation was understood as the activation of several blood coagulation factors by their γ-carboxylation. Over the last two decades, other modes of vitamin K actions have been discovered, such as the regulation of transcription by activating the steroid and xenobiotic receptor (SXR), physical association to 17β-Hydroxysteroid dehydrogenase type 4 (17β-HSD4), covalent modification of Bcl-2 antagonist killer 1 (Bak), and the modulation of protein kinase A (PKA) activity. In addition, several epidemiological studies have revealed that vitamin K status is associated with some aging-related diseases including osteoporosis, osteoarthritis, and sarcopenia. Clinical studies on single nucleotide polymorphisms of GGCX suggested an association between higher GGCX activity and bone protective effect, while recent findings using conditional knockout mice implied that a contribution in protective effect for bone loss by GGCX in osteoblastic lineage was unclear. GGCX in other cell lineages or in other tissues might play a protective role for osteoporosis. Meanwhile, animal experiments by our groups among others revealed that SXR, a putative receptor for vitamin K, could be important in the bone metabolism. In terms of the cartilage protective effect of vitamin K, both GGCX- and SXR-dependent mechanisms have been suggested. In clinical studies on osteoarthritis, the γ-carboxylation of matrix Gla protein (MGP) and gla-rich protein (GRP) may have a protective role for the disease. It is also suggested that SXR signaling has protective role for cartilage by inducing family with sequence similarity 20a (Fam20a) expression in chondrocytes. In the case of sarcopenia, a high vitamin K status in plasma was associated with muscle strength, large muscle mass, and high physical performance in some observational studies. However, the basic studies explaining the effects of vitamin K on muscular tissue are limited. Further research on vitamin K will clarify new biological mechanisms which contribute to human longevity and health through the prevention and treatment of aging-related musculoskeletal disorders.

In the present study we provide evidence that solomonsterol A, a selective pregnane X receptor (PXR) agonist isolated from the marine sponge Theonella swinhoei, exerts anti-inflammatory activity and attenuates systemic inflammation and immune dysfunction in a mouse model of rheumatoid arthritis. Solomonsterol A was effective in protecting against the development of arthritis induced by injecting transgenic mice harboring a humanized PXR, with anti-collagen antibodies (CAIA) with beneficial effects on joint histopathology and local inflammatory response reducing the expression of inflammatory markers (TNFα, IFNγ and IL-17 and chemokines MIP1α and RANTES) in draining lymph nodes. Solomonsterol A rescued mice from systemic inflammation were assessed by measuring arthritis score, CRP and cytokines in the blood. In summary, the present study provides a molecular basis for the regulation of systemic local and systemic immunity by PXR agonists.

Toxic chemicals entered into human body would undergo a series of metabolism, transport and excretion, and the key roles played in there processes were metabolizing enzymes, which was regulated by the pregnane X receptor (PXR). However, some chemicals in environment could activate or antagonize human pregnane X receptor, thereby leading to a disturbance of normal physiological systems. In this study, based on a larger number of 2724 structurally diverse chemicals, we developed qualitative classification models by the k-nearest neighbor method. Moreover, the logarithm of 20 and 50% effective concentrations (log EC and log EC ) was used to establish quantitative structure-activity relationship (QSAR) models. With the classification model, two descriptors were enough to establish acceptable models, with the sensitivity, specificity, and accuracy being larger than 0.7, highlighting a high classification performance of the models. With two QSAR models, the statistics parameters with the correlation coefficient ( R ) of 0.702-0.749 and the cross-validation and external validation coefficient ( Q ) of 0.643-0.712, this indicated that the models complied with the criteria proposed in previous studies, i.e., R > 0.6, Q > 0.5. The small root mean square error ( RMSE) of 0.254-0.414 and the good consistency between observed and predicted values proved satisfactory goodness of fit, robustness, and predictive ability of the developed QSAR models. Additionally, the applicability domains were characterized by the Euclidean distance-based approach and Williams plot, and results indicated that the current models had a wide applicability domain, which especially included a few classes of environmental contaminant, those that were not included in the previous models. [ABSTRACT FROM AUTHOR]

In this study, we presented the role of 14-3-3σ to activate CK2-Hsp90β-PXR-MDR1 pathway on rifampin and paclitaxel treated LS174T cells and in vivo LS174T cell-xenografted nude mouse model. Following several in vitro and in vivo experiments, rifampin and paclitaxel were found to be stimulated the CK2-Hsp90β-PXR-MDR1 pathway. Of the proteins in this pathway, Pregnane X receptor (PXR) is a representative transcription factor of multidrug resistance protein 1 (MDR1). We constructed FLAG-PXR-LS174T stable cell lines and discovered 22 proteins that interacted with PXR on rifampin treatment. Among them, Hsp90β and 14-3-3σ were isolated for further study. Both the proteins were found to be localized in cytoplasm on rifampin treatment by using confocal microscopy. On the other hand, PXR was found to be localized in nucleus after rifampin and paclitaxel treatment by using cell fractionation assay. In Western blot analysis, rifampin did not influence the expression of 14-3-3σ protein. Transient transfection of 14-3-3σ into LS174T cells induced overexpression of PXR; however, P-glycoprotein (P-gp) was not changed significantly. P-gp overexpression was induced only when 14-3-3σ transfected LS174T cells were treated with rifampin and paclitaxel, whereas 14-3-3σ inhibition by nonpeptidic inhibitor, BV02 and 14-3-3σ siRNA reduced rifampin induced PXR and P-gp expression. Cell survival rates were much higher at 14-3-3σ-LS174T stable cell lines than LS174T cells following paclitaxel and vincristine treatment. This data indicates that 14-3-3σ contributes to P-gp overexpression through interaction with PXR with rifampin and paclitaxel treatment. [ABSTRACT FROM AUTHOR]

Understanding the physiological effects of food ingredients on bodily functions is crucial for the development of foods for specified health use (FoSHU) and functional foods. To investigate this, intestinal epithelial cells (IECs) have been widely studied as they are most frequently exposed to the highest concentrations of food ingredients. Among the various functions of IECs, in this review, we have discussed glucose transporters and their involvement in preventing metabolic syndromes such as diabetes. Phytochemicals are also discussed, as they significantly inhibit glucose and fructose absorption via sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 5 (GLUT5), respectively. Additionally, we have focused on the barrier functions of IECs against xenobiotics. Phytochemicals induce detoxification of metabolizing enzymes via pregnane X receptor or aryl hydrocarbon receptor activation, which suggests that food ingredients can enhance barrier function. This review will provide insights into the role of food ingredients and glucose transporters, as well as detoxification metabolizing enzymes in IECs, and help guide future research on these aspects., Competing Interests: Declaration of competing interest The authors have declared no conflict of interest., (Copyright © 2023 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

Inorganic arsenic (iAs) is an environmental toxicant that can lead to severe health consequences, which can be exacerbated if exposure occurs early in development. Here, we evaluated the impact of oral iAs treatment on UDP-glucuronosyltransferase 1A1 (UGT1A1) expression and bilirubin metabolism in humanized UGT1 (hUGT1) mice. We found that oral administration of iAs to neonatal hUGT1 mice that display severe neonatal hyperbilirubinemia leads to induction of intestinal UGT1A1 and a reduction in total serum bilirubin values. Oral iAs administration accelerates neonatal intestinal maturation, an event that is directly associated with UGT1A1 induction. As a reactive oxygen species producer, oral iAs treatment activated the Keap-Nrf2 pathway in the intestinal tract and liver. When Nrf2-deficient hUGT1 mice (hUGT1/Nrf2 -/- ) were treated with iAs, it was shown that activated Nrf2 contributed significantly toward intestinal maturation and UGT1A1 induction. However, hepatic UGT1A1 was not induced upon iAs exposure. We previously demonstrated that the nuclear receptor PXR represses liver UGT1A1 in neonatal hUGT1 mice. When PXR was deleted in hUGT1 mice (hUGT1/Pxr -/- ), derepression of UGT1A1 was evident in both liver and intestinal tissue in neonates. Furthermore, when neonatal hUGT1/Pxr -/- mice were treated with iAs, UGT1A1 was superinduced in both tissues, confirming PXR release derepressed key regulatory elements on the gene that could be activated by iAs exposure. With iAs capable of generating reactive oxygen species in both liver and intestinal tissue, we conclude that PXR deficiency in neonatal hUGT1/Pxr -/- mice allows greater access of activated transcriptional modifiers such as Nrf2 leading to superinduction of UGT1A1., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Published by Elsevier Inc.)

Breast cancer resistance protein (BCRP,ABCG2) is an efflux transporter protein that transports various substrates from the cell to the extracellular space or organ cavities. The aim of this study was a complex assessment of the amount of BCRP during pregnancy in rabbits. The amount of BCRP in samples of the rabbit jejunum, liver, kidney, cerebral cortex, and placenta was determined by enzyme immunoassay, and in human hepatocellular carcinoma (HepG2) cells by the Western blot. To study the mechanisms involved in control of the dynamic BCRP levels during pregnancy, serum concentrations of sex hormones were investigated by radioimmunoassay and relative amounts of constitutive androstane receptor (CAR) and pregnane X receptor (PXR) in these organs were evaluated using the Western blot method. The putative role of CAR and PXR in regulation of the BCRP level by progesterone was evaluated in vitro experiments on HepG2 cells. It was found that amount of BCRP in the jejunum of pregnant rabbits was higher than in the placenta, liver, kidneys, and cerebral cortex. An increase in the amount of BCRP in the liver of rabbits was noted on the 21st day of pregnancy and a tendency to the increase was also detected on the 28th day; in the kidney and cerebral cortex increased BCRP levels were detected on the 28th day and 14th day of pregnancy, respectively, as compared with non-pregnant females. In vitro experiments with HepG2 cells have shown that the increase in the BCRP level is determined by the activating effect of progesterone on PXR.

[Display omitted] 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) has been identified as the primary enzyme responsible for the activation of hepatic cortisone to cortisol in specific peripheral tissues, resulting in the concomitant antagonism of insulin action within these tissues. Dysregulation of 11β-HSD1, particularly in adipose tissues, has been associated with a variety of ailments including metabolic syndrome and type 2 diabetes mellitus. Therefore, inhibition of 11β-HSD1 with a small nonsteroidal molecule is therapeutically desirable. Implementation of a scaffold-hopping approach revealed a 3-point pharmacophore for 11β-HSD1 that was utilized to design a 2-spiroproline derivative as a steroid mimetic scaffold. Reiterative optimization provided valuable insight into the bioactive conformation of our novel scaffold and led to the discovery of several leads, such as compounds 39 and 51. Importantly, deleterious hERG inhibition and pregnane X receptor induction were mitigated by the introduction of a 4-hydroxyl group to the proline ring system. [ABSTRACT FROM AUTHOR]

Pregnane X receptor (PXR) is a major transcriptional regulator of xenobiotic metabolism and transport pathways in the liver and intestines, which are critical for protecting organisms against potentially harmful xenobiotic and endobiotic compounds. Inadvertent activation of drug metabolism pathways through PXR is known to contribute to drug resistance, adverse drug–drug interactions, and drug toxicity in humans. In both humans and rodents, PXR has been implicated in non-alcoholic fatty liver disease, diabetes, obesity, inflammatory bowel disease, and cancer. Because of PXR's important functions, it has been a therapeutic target of interest for a long time. More recent mechanistic studies have shown that PXR is modulated by multiple PTMs. Herein we provide the first investigation of the role of acetylation in modulating PXR activity. Through LC–MS/MS analysis, we identified lysine 109 (K109) in the hinge as PXR's major acetylation site. Using various biochemical and cell-based assays, we show that PXR's acetylation status and transcriptional activity are modulated by E1A binding protein (p300) and sirtuin 1 (SIRT1). Based on analysis of acetylation site mutants, we found that acetylation at K109 represses PXR transcriptional activity. The mechanism involves loss of RXRα dimerization and reduced binding to cognate DNA response elements. This mechanism may represent a promising therapeutic target using modulators of PXR acetylation levels. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie. [ABSTRACT FROM AUTHOR]

1. This study investigated the mechanisms of the decreases of carboxylesterases (CES) and cytochrome P4503A4 (CYP3A4) and the enzymatic activities induced by fluoxetine (FLX) in HepG2 cells. We found that FLX decreased the carboxylesterase 1 (CES1) and carboxylesterase 2 (CES2) expression and the hydrolytic activity. 2. FLX decreased the pregnane X receptor (PXR) expression which regulated the target genes such as CYP3A4, whereas increased the differentiated embryonic chondrocyte-expressed gene 1 (DEC1) expression. 3. FLX repressed the PXR at transcriptional level. 4. Overexpression of PXR alone increased the expression of CES1, CES2, and CYP3A4 and attenuated the decreases of CES1, CES2, and CYP3A4 induced by FLX. On the contrary, knockdown of PXR alone decreased the expression of CES1, CES2, and CYP3A4 and almost abolished the decreases of CES1, CES2, and CYP3A4 induced by FLX. 5. Knockdown of DEC1 alone increased the expression of PXR and CYP3A4 and almost abolished the decreases of CES1, CES2, and CYP3A4 induced by FLX. 6. Taken together, the decreases of CES and CYP3A4 expression and enzymatic activities induced by FLX are through decreasing PXR and increasing DEC1 in HepG2 cells. [ABSTRACT FROM PUBLISHER]

We report the design, synthesis, and physicochemical/biological evaluation of novel silanol derivative 6 (sila-T) as a silanol analog of multi-target nuclear receptor modulator T0901317 ( 5 ). Compound 6 showed intermediate hydrophobicity between the corresponding alcohol 13 and perfluoroalcohol 5 . While 5 exhibited potent activities toward liver X receptor α and β, farnesoid X receptor, pregnane X receptor (PXR) and retinoic acid receptor-related orphan receptor (ROR)γ, silanol 6 exhibited activity only toward PXR and RORs. Incorporation of silanol instead of perfluoroalcohol is a promising option for developing novel target-selective, biologically active compounds. [ABSTRACT FROM AUTHOR]

The translational failure between preclinical animal models and clinical outcome has alarmed us to search for a new strategy in the treatment of Alzheimer's disease (AD). Interlink between Pregnane X Receptor (PXR) and P-glycoprotein (Pgp) at the blood brain barrier (BBB) has raised hope toward a new disease modifying therapy in AD. Pgp is a major efflux transporter for beta amyloid (A $$\upbeta $$ ) at human BBB. A literature survey reveals diminished expression of Pgp transporter at the BBB in AD patients. Pregnane X Receptor is a major transcriptional regulator of Pgp. Restoration of Pgp at the BBB enhances the elimination of the A $$\upbeta $$ from brain alongside and inhibits the apical to basolateral movement of A $$\upbeta $$ from the circulatory blood. This review concentrates on in vitro, in vivo, and in silico advancements on the study of the PXR in context to Pgp and discusses the substrate and inhibitor specificity between PXR and Pgp. [ABSTRACT FROM AUTHOR]

Highlights: [•] Bile acids are important signaling molecules. [•] Bile acids can activate nuclear receptors and GPCRs. [•] Bile acid-mediated signaling pathways play important roles in lipid and glucose metabolism. [•] Dysregulation of bile acid-mediated signaling pathways contributes to various metabolic diseases. [Copyright &y& Elsevier]

Nuclear receptors (NRs) belong to a superfamily of evolutionarily related DNA-binding transcription factors that can be activated by steroid and thyroid hormones, and other lipid metabolites. Ligand activated NRs can regulate target gene expression by binding to DNA response elements present in the target gene promoters. Through this regulation, NRs are broadly implicated in physiology and metabolism. In this chapter, we will focus on the xenobiotic receptors and their recently discovered functions in metabolic diseases. [ABSTRACT FROM AUTHOR]

Abstract: Drug transporters, drug-metabolizing enzymes, and tight junctions in the small intestine function as an absorption barrier and sometimes as a facilitator of orally administered drugs. The expression of these proteins often fluctuates and thereby causes individual pharmacokinetic variability. MicroRNAs (miRNAs), which are small non-coding RNAs, have recently emerged as a new class of gene regulator. MiRNAs post-transcriptionally regulate gene expression by binding to target mRNA to suppress its translation or regulate its degradation. They have been shown to be key regulators of proteins associated with pharmacokinetics. Moreover, the role of miRNAs on the expression of some proteins expressed in the small intestine has recently been clarified. In this review, we summarize current knowledge regarding the role of miRNAs in the regulation of drug transporters, drug-metabolizing enzymes, and tight junctions as well as its implication for intestinal barrier function. MiRNAs play vital roles in the differentiation, architecture, and barrier function of intestinal epithelial cells, and directly and/or indirectly regulate the expression and function of proteins associated with drug absorption in intestinal epithelial cells. Moreover, the variation of miRNA expression caused by pathological and physiological conditions as well as genetic factors should affect the expression of these proteins. Therefore, miRNAs could be significant factors affecting inter- and intra-individual variations in the pharmacokinetics and intestinal absorption of drugs. Overall, miRNAs could be promising targets for personalized pharmacotherapy or other attractive therapies through intestinal absorption of drugs. [Copyright &y& Elsevier]

Abstract: Retinoid X receptor ? (RXR?) forms a heterodimer with numerous nuclear receptors to regulate drug- or lipid-metabolizing enzymes. In this study, we investigated whether human RXR? is regulated by microRNAs. Two potential recognition elements of miR-34a were identified in the RXR? mRNA: one in the coding region and the other in the 3?-untranslated region (3?-UTR). Luciferase assays revealed that miR-34a recognizes the element in the coding region. The overexpression of miR-34a in HepG2 cells significantly decreased the endogenous RXR? protein and mRNA levels. The stability of RXR? mRNA was decreased by the overexpression of miR-34a, indicating that miR-34a negatively regulates RXR? expression by facilitating mRNA degradation. We found that the miR-34a-dependent down-regulation of RXR? decreases the induction of CYP26 and the transactivity of CYP3A4. miR-34a has been reported to be up-regulated by p53, which has an ability to promote liver fibrosis. The p53 activation resulted in an increase of the miR-34a level and a decrease of the RXR? protein level. In addition, the miR-34a levels in eight fibrotic livers were higher than those in six normal livers, and the reverse trend was found for the RXR? protein levels. An inverse correlation was observed between the miR-34a and the RXR? protein levels in the 14 samples. Taken together, the data show that miR-34a negatively regulates RXR? expression in human liver, and affects the expression of its downstream genes. This miR-34a-dependent regulation might be the underlying mechanism responsible for the decreased expression of the RXR? protein in fibrotic livers. [Copyright &y& Elsevier]

Highlights: [•] Clotrimazole concentrates in the plasma and liver of common carp exposed via water. [•] The calculated BCF for clotrimazole in the liver was between 144 and 1691. [•] Measurable levels of clotrimazole remained in the liver after 4 days depuration. [•] Clotrimazole exposure induced expression of a number of biotransformation genes. [•] Expression of drug transporter genes was altered at an environmental relevant concentration. [Copyright &y& Elsevier]

Abstract: The present study assessed if eating a diet of fish, spiked with persistent organic pollutants (POPs), affects gene and protein expression in the maturing mouse brain. Juvenile female Balb/c mice (22 days of age) were exposed for 28 days to fish-based diets spiked with the dioxin 2,3,7,8-tetrachlorodibenzodioxin (TCDD) or the non dioxin-like (NDL) chemicals hexabromocyclodocecane (HBCD), 2,2′4,4′-tetrabromodiphenylether (BDE-47) or 2,2′4,4′,5,5′-hexachlorobiphenyl (CB-153) at doses approximating their respective lowest observed adverse effect levels (LOAEL). It was found that all POPs elicited changes in neural gene and protein expression profiles. Bioinformatic analysis of gene expression data highlighted the importance of the aryl hydrocarbon receptor (AHR) in dioxin toxicity and revealed that zinc regulation in the brain is targeted by TCDD through the AHR. Calcium homeostasis was affected by both TCDD and the NDL chemicals. In contrast to the transcriptomic analysis, the proteomics data did not allow for a clear distinction between DL and NDL responses in the juvenile brain but indicated that proteins associated with excitotoxicity were affected in all exposure groups. Integrated interpretation of data led to the conclusion that the dietary contaminants investigated in the present study breach the blood brain barrier (BBB) and accumulate in the juvenile brain where they may induce excitotoxic insults by dysregulation of the otherwise tightly controlled homeostasis of calcium and zinc. Overall, the findings of the present study highlight the need for further assessment of the risks associated with early life exposure to foodborne POPs. [Copyright &y& Elsevier]

Abstract: ABC transporters including MRP2, MDR1 and BCRP play a major role in tissue defense. Epidemiological and experimental studies suggest a cytoprotective role of estrogens in intestine, though the mechanism remains poorly understood. We evaluated whether pharmacologic concentrations of ethynylestradiol (EE, 0.05pM to 5nM), or concentrations of genistein (GNT) associated with soy ingestion (0.1–10μM), affect the expression and activity of multidrug resistance proteins MRP2, MDR1 and BCRP using Caco-2 cells, an in vitro model of intestinal epithelium. We found that incubation with 5pM EE and 1μM GNT for 48h increased expression and activity of both MRP2 and MDR1. Estrogens did not affect expression of BCRP protein at any concentration studied. Irrespective of the estrogen tested, up-regulation of MDR1 and MRP2 protein was accompanied by increased levels of MDR1 mRNA, whereas MRP2 mRNA remained unchanged. Cytotoxicity assays demonstrated association of MRP2 and MDR1 up-regulation with increased resistance to cell death induced by 1-chloro-2,4-dinitrobenzene, an MRP2 substrate precursor, and by paraquat, an MDR1 substrate. Experiments using an estrogen receptor (ER) antagonist implicate ER participation in MRP2 and MDR1 regulation. GNT but not EE increased the expression of ERβ, the most abundant form in human intestine and in Caco-2 cells, which could lead in turn to increased sensitivity to estrogens. We conclude that specific concentrations of estrogens can confer resistance against cytotoxicity in Caco-2 cells, due in part to positive modulation of ABC transporters involved in extrusion of their toxic substrates. Although extrapolation of these results to the in vivo situation must be cautiously done, the data could explain tentatively the cytoprotective role of estrogens against chemical injury in intestine. [Copyright &y& Elsevier]

Highlights: [•] DINP-exposed toxicity is associated with the overproduction of ROS. [•] Oral exposure to DINP is likely to present hepatic and renal tissue injury. [•] ROS accumulation maybe further causes IL-1 and TNF-α production at increased levels. [ABSTRACT FROM AUTHOR]

Abstract: Obesity is a complex metabolic disorder that is more prevalent among women. Until now, the only relevant rodent models of diet-induced obesity were via the use of ovariectomized (“postmenopausal”) females. However, recent reports suggest that the xenobiotic nuclear receptor pregnane X receptor (PXR) may contribute to obesity. Therefore, we compared the roles of mouse and human PXRs in diet-induced obesity between wild type (WT) and PXR-humanized (hPXR) transgenic female mice fed either control or high-fat diets (HFD) for 16 weeks. HFD-fed hPXR mice gained weight more rapidly than controls, exhibited hyperinsulinemia, and impaired glucose tolerance. Fundamental differences were observed between control-fed hPXR and WT females: hPXR mice possessed reduced estrogen receptor α (ERα) but enhanced uncoupling protein 1 (UCP1) protein expression in white adipose tissue (WAT); increased protein expression of the hepatic cytochrome P450 3A11 (CYP3A11) and key gluconeogenic enzymes phosphoenolpyruvate carboxykinase and glucose 6-phosphatase, and increased total cholesterol. Interestingly, HFD ingestion induced both UCP1 and glucokinase protein expression in WT mice, but inhibited these enzymes in hPXR females. Unlike WT mice, CYP3A11 protein, serum 17β-estradiol levels, and WAT ERα expression were unaffected by HFD in hPXR females. Together, these studies indicate that the hPXR gene promotes obesity and metabolic syndrome by dysregulating lipid and glucose homeostasis while inhibiting UCP1 expression. Furthermore, our studies indicate that the human PXR suppresses the protective role of estrogen in metabolic disorders. Finally, these data identify PXR-humanized mice as a promising in vivo research model for studying obesity and diabetes in women. [Copyright &y& Elsevier]

Abstract: Pregnane X receptor (PXR) regulates cell proliferation and carcinogenesis in female reproductive tissue. We showed that PXR was expressed in cervical cells and tissue samples. PXR were lower or greatly diminished in cancer tissues compared to normal control. Functionally, activation of human PXR by rifampicin or ectopic expression of constitutively-activated human VP-PXR inhibited cervical cell proliferation. Constitutively-activated VP-PXR attenuated CaSki and HeLa xenograft tumor growth in nude mice compared with control. The cellular proliferation inhibition of PXR by causing G2/M cell-cycle arrest is involved up-regulation of Cullin1-3, MAD2L1, and down-regulation of ANAPC2 and CDKN1A. Our data suggests that PXR signaling inhibits tumor cell proliferation in vitro and cervical carcinoma growth in vivo. [Copyright &y& Elsevier]

Highlights: [•] 5β-Reduced steroids are metabolites of Δ4-3-ketosteroids. [•] 5β-Reduced androstanes, pregnanes, and cholanes perform biological functions. [•] All mammalian bile-acids are 5β-cholanes. [•] Aldo–keto reductase (AKR) 1D1 is the only human 5β-reductase. [•] Structure–function studies on AKR1D1 provide a basis for bile-acid deficiency. [Copyright &y& Elsevier]

Highlights: [•] We isolated cDNAs of AHR2, Sult1 st1, Ugt2a1 and Ugt2b6 in rare minnow. [•] Sexually dimorphic in hepatic transcripts of Cyp1a was found in adult rare minnow. [•] AHR2 and PXR are vital in regulating biotransformation enzymes in MT catabolism. [•] UGT2A1 is more effective than SULT1 ST4 and SULT1 ST6 in MT catabolism in males. [Copyright &y& Elsevier]

Abstract: The increased uptake and storage of lipids in the liver are important features of steatotic liver diseases. The fatty acid translocase/scavenger receptor cluster of differentiation (CD)36 facilitates the hepatic uptake of lipids. We investigated if RRR-α-tocopherol (αT) alone or in combination with atorvastatin (ATV) is capable of preventing hepatic lipid accumulation via down-regulation of CD36. To this end, Dunkin Hartley guinea pigs were fed a control diet (5% fat); or a high-fat control diet (21% fat, 0.15% cholesterol); or a high-fat control diet fortified with αT (250 mg/kg diet), ATV (300 mg/kg diet) or both ATV+αT for 6 weeks. Hepatic triacylglycerols, hepatic protein and mRNA expression of CD36 as well as the mRNA expression of the controlling nuclear receptors LXRα, PXR and PPARγ were determined. Animals fed the high-fat control diet accumulated significantly more triacylglycerols in the liver than control animals. This was significantly reduced by ATV and numerically by αT and ATV+αT. Hepatic CD36 protein concentrations were significantly higher in the high-fat than in the control group, and both αT and ATV reduced CD36 expression to the level observed in the control group. However, no synergistic effect of the combined treatment was observed. Neither CD36 mRNA nor that of the nuclear receptors (LXRα, PXR and PPARγ) differed between groups, suggesting a posttranslational regulatory mechanism. Our results indicate that orally administered ATV and αT individually, but not synergistically, prevent diet-induced lipid accumulation in the liver of guinea pigs by down-regulation of hepatic CD36 protein. [Copyright &y& Elsevier]

Highlights: [•] FL442 is selective to AR over other closely related steroid hormone receptors. [•] FL442 exhibits equal efficacy to prevent PCa cell proliferation as enzalutamide. [•] FL442 maintains antiandrogenic activity with enzalutamide-activated ARF876L. [•] FL442 accumulates strongly in the mouse prostate. [•] FL442 significantly inhibits LNCaP xenograft tumor growth. [Copyright &y& Elsevier]

Abstract: The small intestine plays a fundamentally important role in regulating whole body cholesterol balance and plasma lipoprotein composition. This is articulated through the interplay of a constellation of genes that ultimately determines the net amount of chylomicron cholesterol delivered to the liver. Major advances in our insights into regulation of the cholesterol absorption pathway have been made using genetically manipulated mouse models and agents such as ezetimibe. One unresolved question is how a sustained pharmacological inhibition of intestinal cholesterol synthesis in vivo may affect cholesterol handling by the absorptive cells. Here we show that the lanosterol cyclase inhibitor, Ro 48-8071, when fed to BALB/c mice in a chow diet (20mg/day/kg body weight), leads to a rapid and sustained inhibition (>50%) of cholesterol synthesis in the whole small intestine. Sterol synthesis was also reduced in the large intestine and stomach. In contrast, hepatic cholesterol synthesis, while markedly suppressed initially, rebounded to higher than baseline rates within 7 days. Whole body cholesterol synthesis, fractional cholesterol absorption, and fecal neutral and acidic sterol excretion were not consistently changed with Ro 48-8071 treatment. There were no discernible effects of this agent on intestinal histology as determined by H&E staining and the level of Ki67, an index of proliferation. The mRNA expression for multiple genes involved in intestinal cholesterol regulation including NPC1L1 was mostly unchanged although there was a marked rise in the mRNA level for the PXR target genes CYP3A11 and CES2A. [Copyright &y& Elsevier]

The hPXR (human pregnane X receptor), a major chemical toxin sensor, is a ligand-induced transcription factor activated by various xenobiotics and toxins, resulting in the transcriptional up-regulation of detoxifying enzymes. To date, little is known about the upstream regulation of hPXR. Using MS analysis and a kinome-wide siRNA screen, we report that the E3 ligase UBR5 (ubiquitin protein ligase E3 component n-recognin 5) and DYRK2 (dual-specificity tyrosine-phosphorylation-regulated kinase 2) regulate hPXR stability. UBR5 knockdown resulted in accumulation of cellular hPXR and a concomitant increase in hPXR activity, where as the rescue ofUBR5 knockdown decreased the cellular hPXR level and activity. Importantly, UBR5 exerted its effect in concert with the serine/threonine kinase DYRK2, as the knockdown of DYRK2 phenocopied UBR5 knockdown. hPXR was shown to be a substrate for DYRK2, and DYRK2-dependent phosphorylation of hPXR facilitated its subsequent ubiquitination by UBR5. This is the first report of the posttranslational regulation of hPXR via phosphorylation-facilitated ubiquitination by DYRK2 and UBR5. The results of the present study reveal the role of the ubiquitin-proteasomal pathway in modulating hPXR activity and indicate that pharmacological inhibitors of the ubiquitin-proteasomal pathway that regulate hPXR stability may negatively affect treatment outcome from unintended hPXR-mediated drug-drug interactions. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Computational methods have been widely applied to toxicology across pharmaceutical, consumer product and environmental fields over the past decade. Progress in computational toxicology is now reviewed. Methods: A literature review was performed on computational models for hepatotoxicity (e.g. for drug-induced liver injury (DILI)), cardiotoxicity, renal toxicity and genotoxicity. In addition various publications have been highlighted that use machine learning methods. Several computational toxicology model datasets from past publications were used to compare Bayesian and Support Vector Machine (SVM) learning methods. Results: The increasing amounts of data for defined toxicology endpoints have enabled machine learning models that have been increasingly used for predictions. It is shown that across many different models Bayesian and SVM perform similarly based on cross validation data. Discussion: Considerable progress has been made in computational toxicology in a decade in both model development and availability of larger scale or ‘big data’ models. The future efforts in toxicology data generation will likely provide us with hundreds of thousands of compounds that are readily accessible for machine learning models. These models will cover relevant chemistry space for pharmaceutical, consumer product and environmental applications. [Copyright &y& Elsevier]

Highlights: [•] Integrated analysis of multi-omics datasets yields insight into EE liver toxicity. [•] Cholestasis and oxidative stress are involved in EE-induced liver injury. [•] Anti-cholestatic adaptive mechanism is mediated through ABC transporters pathway. [ABSTRACT FROM AUTHOR]

Abstract: In pigs the endogenously produced compound androstenone is metabolised in the liver in two steps by 3β-hydroxysteroid dehydrogenase (3β-HSD) and sulphotransferase 2A1 (SULT2A1). The present study investigated the effect of selected sex-steroids (0.01–1μM androstenone, testosterone and estradiol), skatole (1–100μM) and secondary plant metabolites (1–100μM) on the expression of 3β-HSD and SULT2A1 mRNA. Additionally the effect of a global methanolic extract of dried chicory root was investigated and compared to previous obtained in vivo effects. Primary hepatocytes were isolated from the livers of piglets (crossbreed: Landrace×Yorkshire and Duroc) and cultured for 24h before treatment for an additionally 24h. RNA was isolated from the hepatocytes and specific gene expression determined by RT-PCR using TaqMan probes. The investigated sex-steroids had no effect on the mRNA expression of 3β-HSD and SULT2A1, while skatole decreased the content of SULT2A1 30% compared to control. Of the investigated secondary plant metabolites artemisinin and scoparone (found in Artemisia sp.) lowered the content of SULT2A1 by 20 and 30% compared to control, respectively. Moreover, we tested three secondary plant metabolites (lactucin, esculetin and esculin) found in chicory root. Lactucin increased the mRNA content of both 3β-HSD and SULT2A1 by 200% compared to control. An extract of chicory root was shown to decrease the expression of both 3β-HSD and SULT2A1. It is concluded that the gene expression of enzymes with importance for androstenone metabolism is regulated by secondary plant metabolites in a complex manner. [Copyright &y& Elsevier]