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Nilles J, Weiss J, Masin M, Tuffs C, Strowitzki MJ, Haefeli WE, Ruez S, Theile D. The differences in drug disposition gene induction by rifampicin and rifabutin are unlikely due to different effects on important pregnane X receptor (NR1I2) splice variants. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:2485-2496. [PMID: 37851058 PMCID: PMC10933196 DOI: 10.1007/s00210-023-02768-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/02/2023] [Indexed: 10/19/2023]
Abstract
Rifampicin and rifabutin can activate the pregnane X receptor (PXR, NR1I2), thereby inducing pharmacokinetically important genes/proteins and reducing exposure to co-administered drugs. Because induction effects vary considerably between these antibiotics, differences could be due to unequal rifamycin-induced activation or tissue expression of the three major NR1I2 splice variants, PXR.1 (NM_003889), PXR.2 (NM_022002), and PXR.3 (NM_033013). Consequently, PXR activation (PXR reporter gene assays) and mRNA expression levels of total NR1I2, PXR.1, PXR.2, and PXR.3 were investigated by polymerase chain reaction in colon and liver samples from eleven surgical patients, in LS180 cells, and primary human hepatocytes. Compared to the colon, total NR1I2 mRNA expression was higher in the liver. Both tissues showed similar expression levels of PXR.1 and PXR.3, respectively. PXR.2 was not quantifiable in the colon samples. Rifampicin and rifabutin similarly enhanced PXR.1 and PXR.2 activity when transfected into LS180 cells, while PXR.3 could not be activated. In LS180 cells, rifampicin (10 μM) reduced total NR1I2 and PXR.3 expression 2-fold after 24 h, while rifabutin (10 μM) increased total NR1I2, PXR.1, PXR.2, and PXR.3 mRNA by approx. 50% after 96-h exposure. In primary human hepatocytes, rifampicin (10 μM) suppressed total NR1I2, PXR.1, and PXR.3 after 48-h exposure, and rifabutin (10 μM) had no significant impact on total NR1I2 or any of the splice variants studied. In conclusion, both antibiotics activated the studied PXR splice variants similarly but modified their expression differently. While rifampicin can suppress mRNA of PXR forms, rifabutin rather increases their expression levels.
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Affiliation(s)
- Julie Nilles
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- Boehringer Ingelheim Pharma GmbH & Co, KG, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany
| | - Johanna Weiss
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Martin Masin
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Christopher Tuffs
- Departments of General, Visceral, and Transplantation Surgery, Heidelberg University Hospital, Im Neuenheimer Feld 420, 69120, Heidelberg, Germany
| | - Moritz J Strowitzki
- Departments of General, Visceral, and Transplantation Surgery, Heidelberg University Hospital, Im Neuenheimer Feld 420, 69120, Heidelberg, Germany
| | - Walter E Haefeli
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Stephanie Ruez
- Boehringer Ingelheim Pharma GmbH & Co, KG, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany
| | - Dirk Theile
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany.
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2
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Dvořák Z, Li H, Mani S. Microbial Metabolites as Ligands to Xenobiotic Receptors: Chemical Mimicry as Potential Drugs of the Future. Drug Metab Dispos 2023; 51:219-227. [PMID: 36184080 PMCID: PMC9900867 DOI: 10.1124/dmd.122.000860] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 08/28/2022] [Accepted: 09/19/2022] [Indexed: 01/31/2023] Open
Abstract
Xenobiotic receptors, such as the pregnane X receptor, regulate multiple host physiologic pathways including xenobiotic metabolism, certain aspects of cellular metabolism, and innate immunity. These ligand-dependent nuclear factors regulate gene expression via genomic recognition of specific promoters and transcriptional activation of the gene. Natural or endogenous ligands are not commonly associated with this class of receptors; however, since these receptors are expressed in a cell-type specific manner in the liver and intestines, there has been significant recent effort to characterize microbially derived metabolites as ligands for these receptors. In general, these metabolites are thought to be weak micromolar affinity ligands. This journal anniversary minireview focuses on recent efforts to derive potentially nontoxic microbial metabolite chemical mimics that could one day be developed as drugs combating xenobiotic receptor-modifying pathophysiology. The review will include our perspective on the field and recommend certain directions for future research. SIGNIFICANCE STATEMENT: Xenobiotic receptors (XRs) regulate host drug metabolism, cellular metabolism, and immunity. Their presence in host intestines allows them to function not only as xenosensors but also as a response to the complex metabolic environment present in the intestines. Specifically, this review focuses on describing microbial metabolite-XR interactions and the translation of these findings toward discovery of novel chemical mimics as potential drugs of the future for diseases such as inflammatory bowel disease.
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Affiliation(s)
- Zdeněk Dvořák
- Department of Cell Biology and Genetics, Palacký University, Olomouc, Czech Republic (Z.D.); Departments of Medicine (H.L., S.M.), Molecular Pharmacology (S.M.), and Genetics (S.M.), Albert Einstein College of Medicine, Bronx, New York, USA
| | - Hao Li
- Department of Cell Biology and Genetics, Palacký University, Olomouc, Czech Republic (Z.D.); Departments of Medicine (H.L., S.M.), Molecular Pharmacology (S.M.), and Genetics (S.M.), Albert Einstein College of Medicine, Bronx, New York, USA
| | - Sridhar Mani
- Department of Cell Biology and Genetics, Palacký University, Olomouc, Czech Republic (Z.D.); Departments of Medicine (H.L., S.M.), Molecular Pharmacology (S.M.), and Genetics (S.M.), Albert Einstein College of Medicine, Bronx, New York, USA
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3
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The Nuclear Receptor PXR in Chronic Liver Disease. Cells 2021; 11:cells11010061. [PMID: 35011625 PMCID: PMC8750019 DOI: 10.3390/cells11010061] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/21/2021] [Accepted: 12/24/2021] [Indexed: 02/06/2023] Open
Abstract
Pregnane X receptor (PXR), a nuclear receptor known for modulating the transcription of drug metabolizing enzymes and transporters (DMETs), such as cytochrome P450 3A4 and P-glycoprotein, is functionally involved in chronic liver diseases of different etiologies. Furthermore, PXR activity relates to that of other NRs, such as constitutive androstane receptor (CAR), through a crosstalk that in turn orchestrates a complex network of responses. Thus, besides regulating DMETs, PXR signaling is involved in both liver damage progression and repair and in the neoplastic transition to hepatocellular carcinoma. We here summarize the present knowledge about PXR expression and function in chronic liver diseases characterized by different etiologies and clinical outcome, focusing on the molecular pathways involved in PXR activity. Although many molecular details of these finely tuned networks still need to be fully understood, we conclude that PXR and its modulation could represent a promising pharmacological target for the identification of novel therapeutical approaches to chronic liver diseases.
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Mukha A, Kalkhoven E, van Mil SWC. Splice variants of metabolic nuclear receptors: Relevance for metabolic disease and therapeutic targeting. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166183. [PMID: 34058349 DOI: 10.1016/j.bbadis.2021.166183] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/17/2021] [Accepted: 05/25/2021] [Indexed: 12/13/2022]
Abstract
Metabolic nuclear receptors are ligand-activated transcription factors which control a wide range of metabolic processes and signaling pathways in response to nutrients and xenobiotics. Targeting these NRs is at the forefront of our endeavours to generate novel treatment options for diabetes, metabolic syndrome and fatty liver disease. Numerous splice variants have been described for these metabolic receptors. Structural changes, as a result of alternative splicing, lead to functional differences among NR isoforms, resulting in the regulation of different metabolic pathways by these NR splice variants. In this review, we describe known splice variants of FXR, LXRs, PXR, RXR, LRH-1, CAR and PPARs. We discuss their structure and functions, and elaborate on the regulation of splice variant abundance by nutritional signals. We conclude that NR splice variants pose an intriguing new layer of complexity in metabolic signaling, which needs to be taken into account in the development of treatment strategies for metabolic diseases.
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Affiliation(s)
- Anna Mukha
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands
| | - Eric Kalkhoven
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands
| | - Saskia W C van Mil
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands.
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Smutny T, Hyrsova L, Braeuning A, Ingelman-Sundberg M, Pavek P. Transcriptional and post-transcriptional regulation of the pregnane X receptor: a rationale for interindividual variability in drug metabolism. Arch Toxicol 2020; 95:11-25. [PMID: 33164107 DOI: 10.1007/s00204-020-02916-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 09/17/2020] [Indexed: 12/15/2022]
Abstract
The pregnane X receptor (PXR, encoded by the NR1I2 gene) is a ligand-regulated transcription factor originally described as a master regulator of xenobiotic detoxification. Later, however, PXR was also shown to interact with endogenous metabolism and to be further associated with various pathological states. This review focuses predominantly on such aspects, currently less covered in literature, as the control of PXR expression per se in the context of inter-individual differences in drug metabolism. There is growing evidence that non-coding RNAs post-transcriptionally regulate PXR. Effects on PXR have especially been reported for microRNAs (miRNAs), which include miR-148a, miR-18a-5p, miR-140-3p, miR-30c-1-3p and miR-877-5p. Likewise, miRNAs control the expression of both transcription factors involved in PXR expression and regulators of PXR function. The impact of NR1I2 genetic polymorphisms on miRNA-mediated PXR regulation is also discussed. As revealed recently, long non-coding RNAs (lncRNAs) appear to interfere with PXR expression. Reciprocally, PXR activation regulates non-coding RNA expression, thus comprising another level of PXR action in addition to the direct transactivation of protein-coding genes. PXR expression is further controlled by several transcription factors (cross-regulation) giving rise to different PXR transcript variants. Controversies remain regarding the suggested role of feedback regulation (auto-regulation) of PXR expression. In this review, we comprehensively summarize the miRNA-mediated, lncRNA-mediated and transcriptional regulation of PXR expression, and we propose that deciphering the precise mechanisms of PXR expression may bridge our knowledge gap in inter-individual differences in drug metabolism and toxicity.
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Affiliation(s)
- Tomas Smutny
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05, Hradec Kralove, Czech Republic.
| | - Lucie Hyrsova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05, Hradec Kralove, Czech Republic
| | - Albert Braeuning
- Department Food Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589, Berlin, Germany
| | - Magnus Ingelman-Sundberg
- Department of Physiology and Pharmacology, Section of Pharmacogenetics, Karolinska Institutet, Solna vägen 9, 17165, Stockholm, Sweden
| | - Petr Pavek
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203, 500 05, Hradec Kralove, Czech Republic
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Daujat-Chavanieu M, Gerbal-Chaloin S. Regulation of CAR and PXR Expression in Health and Disease. Cells 2020; 9:E2395. [PMID: 33142929 PMCID: PMC7692647 DOI: 10.3390/cells9112395] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/22/2020] [Accepted: 10/28/2020] [Indexed: 12/12/2022] Open
Abstract
Pregnane X receptor (PXR, NR1I2) and constitutive androstane receptor (CAR, NR1I3) are members of the nuclear receptor superfamily that mainly act as ligand-activated transcription factors. Their functions have long been associated with the regulation of drug metabolism and disposition, and it is now well established that they are implicated in physiological and pathological conditions. Considerable efforts have been made to understand the regulation of their activity by their cognate ligand; however, additional regulatory mechanisms, among which the regulation of their expression, modulate their pleiotropic effects. This review summarizes the current knowledge on CAR and PXR expression during development and adult life; tissue distribution; spatial, temporal, and metabolic regulations; as well as in pathological situations, including chronic diseases and cancers. The expression of CAR and PXR is modulated by complex regulatory mechanisms that involve the interplay of transcription factors and also post-transcriptional and epigenetic modifications. Moreover, many environmental stimuli affect CAR and PXR expression through mechanisms that have not been elucidated.
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Affiliation(s)
| | - Sabine Gerbal-Chaloin
- IRMB, University of Montpellier, INSERM, CHU Montpellier, 34295 Montpellier, France;
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Wang J, Bwayi M, Florke Gee RR, Chen T. PXR-mediated idiosyncratic drug-induced liver injury: mechanistic insights and targeting approaches. Expert Opin Drug Metab Toxicol 2020; 16:711-722. [PMID: 32500752 PMCID: PMC7429329 DOI: 10.1080/17425255.2020.1779701] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 06/04/2020] [Indexed: 01/03/2023]
Abstract
INTRODUCTION The human liver is the center for drug metabolism and detoxification and is, therefore, constantly exposed to toxic chemicals. The loss of liver function as a result of this exposure is referred to as drug-induced liver injury (DILI). The pregnane X receptor (PXR) is the primary regulator of the hepatic drug-clearance system, which plays a critical role in mediating idiosyncratic DILI. AREAS COVERED This review is focused on common mechanisms of PXR-mediated DILI and on in vitro and in vivo models developed to predict and assess DILI. It also provides an update on the development of PXR antagonists that may manage PXR-mediated DILI. EXPERT OPINION DILI can be caused by many factors, and PXR is clearly linked to DILI. Although emerging data illustrate how PXR mediates DILI and how PXR activity can be modulated, many questions concerning the development of effective PXR modulators remain. Future research should be focused on determining the mechanisms regulating PXR functions in different cellular contexts.
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Affiliation(s)
- Jingheng Wang
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Monicah Bwayi
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Rebecca R. Florke Gee
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
- Graduate School of Biomedical Sciences, St. Jude Children’s Research Hospital, Memphis, TN, 38105, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
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Xing Y, Yan J, Niu Y. PXR: a center of transcriptional regulation in cancer. Acta Pharm Sin B 2020; 10:197-206. [PMID: 32082968 PMCID: PMC7016272 DOI: 10.1016/j.apsb.2019.06.012] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 06/10/2019] [Accepted: 06/20/2019] [Indexed: 02/05/2023] Open
Abstract
Pregnane X receptor (PXR, NR1I2) is a prototypical member of the nuclear receptor superfamily. PXR can be activated by both endobiotics and xenobiotics. As a key xenobiotic receptor, the cellular function of PXR is mostly exerted by its binding to the regulatory gene sequences in a ligand-dependent manner. Classical downstream target genes of PXR participate in xenobiotic responses, such as detoxification, metabolism and inflammation. Emerging evidence also implicates PXR signaling in the processes of apoptosis, cell cycle arrest, proliferation, angiogenesis and oxidative stress, which are closely related to cancer. Here, we discussed, in addition to the characterization of PXR per se, the biological function and regulatory mechanism of PXR signaling in cancer, and its potential for the targeted prevention and therapeutics.
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Affiliation(s)
- Yaqi Xing
- Department of Pharmacology, Shantou University Medical College, Shantou 515041, China
| | - Jiong Yan
- Center for Pharmacogenetics, University of Pittsburgh, PA 15261, USA
| | - Yongdong Niu
- Department of Pharmacology, Shantou University Medical College, Shantou 515041, China
- Corresponding author.
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Hlady RA, Zhao X, Pan X, Yang JD, Ahmed F, Antwi SO, Giama NH, Patel T, Roberts LR, Liu C, Robertson KD. Genome-wide discovery and validation of diagnostic DNA methylation-based biomarkers for hepatocellular cancer detection in circulating cell free DNA. Am J Cancer Res 2019; 9:7239-7250. [PMID: 31695765 PMCID: PMC6831291 DOI: 10.7150/thno.35573] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Accepted: 03/09/2019] [Indexed: 02/06/2023] Open
Abstract
Hepatocellular carcinoma (HCC), the most prevalent form of liver cancer, is growing in incidence but treatment options remain limited, particularly for late stage disease. As liver cirrhosis is the principal risk state for HCC development, markers to detect early HCC within this patient population are urgently needed. Perturbation of epigenetic marks, such as DNA methylation (5mC), is a hallmark of human cancers, including HCC. Identification of regions with consistently altered 5mC levels in circulating cell free DNA (cfDNA) during progression from cirrhosis to HCC could therefore serve as markers for development of minimally-invasive screens of early HCC diagnosis and surveillance. Methods: To discover DNA methylation derived biomarkers of HCC in the background of liver cirrhosis, we profiled genome-wide 5mC landscapes in patient cfDNA using the Infinium HumanMethylation450k BeadChip Array. We further linked these findings to primary tissue data available from TCGA and other public sources. Using biological and statistical frameworks, we selected CpGs that robustly differentiated cirrhosis from HCC in primary tissue and cfDNA followed by validation in an additional independent cohort. Results: We identified CpGs that segregate patients with cirrhosis, from patients with HCC within a cirrhotic liver background, through genome-wide analysis of cfDNA 5mC landscapes. Lasso regression analysis pinpointed a panel of probes in our discovery cohort that were validated in two independent datasets. A panel of five CpGs (cg04645914, cg06215569, cg23663760, cg13781744, and cg07610777) yielded area under the receiver operating characteristic (AUROC) curves of 0.9525, 0.9714, and 0.9528 in cfDNA discovery and tissue validation cohorts 1 and 2, respectively. Validation of a 5-marker panel created from combining hypermethylated and hypomethylated CpGs in an independent cfDNA set by bisulfite pyrosequencing yielded an AUROC of 0.956, compared to the discovery AUROC of 0.996. Conclusion: Our finding that 5mC markers derived from primary tissue did not perform well in cfDNA, compared to those identified directly from cfDNA, reveals potential advantages of starting with cfDNA to discover high performing markers for liquid biopsy development.
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Ligand-dependent and -independent regulation of human hepatic sphingomyelin phosphodiesterase acid-like 3A expression by pregnane X receptor and crosstalk with liver X receptor. Biochem Pharmacol 2017; 136:122-135. [DOI: 10.1016/j.bcp.2017.04.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 04/12/2017] [Indexed: 11/18/2022]
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Caligiuri A, Gentilini A, Marra F. Molecular Pathogenesis of NASH. Int J Mol Sci 2016; 17:ijms17091575. [PMID: 27657051 PMCID: PMC5037841 DOI: 10.3390/ijms17091575] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 09/05/2016] [Accepted: 09/07/2016] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic steatohepatitis (NASH) is the main cause of chronic liver disease in the Western world and a major health problem, owing to its close association with obesity, diabetes, and the metabolic syndrome. NASH progression results from numerous events originating within the liver, as well as from signals derived from the adipose tissue and the gastrointestinal tract. In a fraction of NASH patients, disease may progress, eventually leading to advanced fibrosis, cirrhosis and hepatocellular carcinoma. Understanding the mechanisms leading to NASH and its evolution to cirrhosis is critical to identifying effective approaches for the treatment of this condition. In this review, we focus on some of the most recent data reported on the pathogenesis of NASH and its fibrogenic progression, highlighting potential targets for treatment or identification of biomarkers of disease progression.
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Affiliation(s)
- Alessandra Caligiuri
- Dipartimento di Medicina Sperimentale e Clinica, Università degli Studi di Firenze, Firenze 50121, Italy.
| | - Alessandra Gentilini
- Dipartimento di Medicina Sperimentale e Clinica, Università degli Studi di Firenze, Firenze 50121, Italy.
| | - Fabio Marra
- Dipartimento di Medicina Sperimentale e Clinica, Università degli Studi di Firenze, Firenze 50121, Italy.
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Brewer CT, Chen T. PXR variants: the impact on drug metabolism and therapeutic responses. Acta Pharm Sin B 2016; 6:441-449. [PMID: 27709012 PMCID: PMC5045535 DOI: 10.1016/j.apsb.2016.07.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 04/21/2016] [Accepted: 05/04/2016] [Indexed: 01/30/2023] Open
Abstract
The pregnane X receptor (PXR) plays an important and diverse role in mediating xenobiotic induction of drug-metabolizing enzymes and transporters. Several protein isoforms of PXR exist, and they have differential transcriptional activity upon target genes; transcript variants 3 (PXR3) and 4 (PXR4) do not induce target gene expression, whereas transcript variants 1 (PXR1) and 2 (PXR2) respond to agonist by activating target gene expression. PXR protein variants also display differences in protein-protein interactions; PXR1 interacts with p53, whereas PXR3 does not. Furthermore, the transcript variants of PXR that encode these protein isoforms are differentially regulated by methylation and deletions in the respective promoters of the variants, and their expression differs in various human cancers and also in cancerous tissue compared to adjacent normal tissues. PXR1 and PXR4 mRNA are downregulated by methylation in cancerous tissue and have divergent effects on cellular proliferation when ectopically overexpressed. Additional detailed and comparative mechanistic studies are required to predict the effect of PXR transcript variant expression on carcinogenesis, therapeutic response, and the development of toxicity.
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Key Words
- AF, activating function
- BAMCA, bacterial artificial chromosome array–based methylated CpG island amplification
- CYP, cytochrome P450
- Drug metabolism
- GST, glutathione S-transferase
- MDR, multidrug resistance protein
- NHR, nuclear hormone receptor
- P-gp, P-glycoprotein
- PXR1, PXR transcript variant 1 (434 residues)
- PXR2, transcript variant 2 (473 residues)
- PXR3, transcript variant 3 (397 residues)
- PXR4, transcript variant 4 (322 residues;AK122990)
- Pregnane X receptor
- RACE, 5′ rapid amplification of cDNA ends
- Therapeutic responses
- Toxicity
- Transcript variants
- UGT, UDP-glucuronosyltransferase
- UTR, untranslated region
- shRNA, short hairpin RNA
- siRNA, small interfering RNA
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Affiliation(s)
- C. Trent Brewer
- Department of Chemical Biology and Therapeutics, St. Jude Children′s Research Hospital, Memphis, TN 38105, USA
- Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children′s Research Hospital, Memphis, TN 38105, USA
- Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, Memphis, TN 38163, USA
- Corresponding author at: Department of Chemical Biology and Therapeutics, St. Jude Children′s Research Hospital, Mail Stop #1000, 262 Danny Thomas Place, Memphis, TN 38105, USA. Tel.: +1 901 595 5937; fax: +1 901 595 5715.Department of Chemical Biology and Therapeutics, St. Jude Children′s Research Hospital, Mail Stop #1000, 262 Danny Thomas PlaceMemphisTN38105USA
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Pondugula SR, Pavek P, Mani S. Pregnane X Receptor and Cancer: Context-Specificity is Key. NUCLEAR RECEPTOR RESEARCH 2016; 3. [PMID: 27617265 DOI: 10.11131/2016/101198] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pregnane X receptor (PXR) is an adopted orphan nuclear receptor that is activated by a wide-range of endobiotics and xenobiotics, including chemotherapy drugs. PXR plays a major role in the metabolism and clearance of xenobiotics and endobiotics in liver and intestine via induction of drug-metabolizing enzymes and drug-transporting proteins. However, PXR is expressed in several cancer tissues and the accumulating evidence strongly points to the differential role of PXR in cancer growth and progression as well as in chemotherapy outcome. In cancer cells, besides regulating the gene expression of enzymes and proteins involved in drug metabolism and transport, PXR also regulates other genes involved in proliferation, metastasis, apoptosis, anti-apoptosis, inflammation, and oxidative stress. In this review, we focus on the differential role of PXR in a variety of cancers, including prostate, breast, ovarian, endometrial, and colon. We also discuss the future directions to further understand the differential role of PXR in cancer, and conclude with the need to identify novel selective PXR modulators to target PXR in PXR-expressing cancers.
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Affiliation(s)
- Satyanarayana R Pondugula
- Department of Anatomy, Physiology and Pharmacology, Auburn University, Auburn, AL 36849, USA; Auburn University Research Initiative in Cancer, Auburn University, Auburn, AL 36849, USA
| | - Petr Pavek
- Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Heyrovského 1203, Hradec Králové 500 05, Czech Republic, European Union
| | - Sridhar Mani
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, New York, NY 10461, USA
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Cave MC, Clair HB, Hardesty JE, Falkner KC, Feng W, Clark BJ, Sidey J, Shi H, Aqel BA, McClain CJ, Prough RA. Nuclear receptors and nonalcoholic fatty liver disease. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1083-1099. [PMID: 26962021 DOI: 10.1016/j.bbagrm.2016.03.002] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 02/29/2016] [Accepted: 03/01/2016] [Indexed: 02/08/2023]
Abstract
Nuclear receptors are transcription factors which sense changing environmental or hormonal signals and effect transcriptional changes to regulate core life functions including growth, development, and reproduction. To support this function, following ligand-activation by xenobiotics, members of subfamily 1 nuclear receptors (NR1s) may heterodimerize with the retinoid X receptor (RXR) to regulate transcription of genes involved in energy and xenobiotic metabolism and inflammation. Several of these receptors including the peroxisome proliferator-activated receptors (PPARs), the pregnane and xenobiotic receptor (PXR), the constitutive androstane receptor (CAR), the liver X receptor (LXR) and the farnesoid X receptor (FXR) are key regulators of the gut:liver:adipose axis and serve to coordinate metabolic responses across organ systems between the fed and fasting states. Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease and may progress to cirrhosis and even hepatocellular carcinoma. NAFLD is associated with inappropriate nuclear receptor function and perturbations along the gut:liver:adipose axis including obesity, increased intestinal permeability with systemic inflammation, abnormal hepatic lipid metabolism, and insulin resistance. Environmental chemicals may compound the problem by directly interacting with nuclear receptors leading to metabolic confusion and the inability to differentiate fed from fasting conditions. This review focuses on the impact of nuclear receptors in the pathogenesis and treatment of NAFLD. Clinical trials including PIVENS and FLINT demonstrate that nuclear receptor targeted therapies may lead to the paradoxical dissociation of steatosis, inflammation, fibrosis, insulin resistance, dyslipidemia and obesity. Novel strategies currently under development (including tissue-specific ligands and dual receptor agonists) may be required to separate the beneficial effects of nuclear receptor activation from unwanted metabolic side effects. The impact of nuclear receptor crosstalk in NAFLD is likely to be profound, but requires further elucidation. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.
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Affiliation(s)
- Matthew C Cave
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA; The Robley Rex Veterans Affairs Medical Center, Louisville, KY 40206, USA; The KentuckyOne Health Jewish Hospital Liver Transplant Program, Louisville, KY 40202, USA.
| | - Heather B Clair
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Josiah E Hardesty
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - K Cameron Falkner
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Wenke Feng
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Barbara J Clark
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Jennifer Sidey
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Hongxue Shi
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Bashar A Aqel
- Department of Medicine, Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Scottsdale, AZ 85054, USA
| | - Craig J McClain
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA; The Robley Rex Veterans Affairs Medical Center, Louisville, KY 40206, USA; The KentuckyOne Health Jewish Hospital Liver Transplant Program, Louisville, KY 40202, USA
| | - Russell A Prough
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
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