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Casiano-Muñiz IM, Ortiz-Román MI, Carmona-Negrón JA, Román-Velázquez FR. UV filter benzophenone-2: Effects on zebrafish (Danio rerio) cytochrome P450. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 273:106973. [PMID: 38861792 DOI: 10.1016/j.aquatox.2024.106973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 05/17/2024] [Accepted: 05/25/2024] [Indexed: 06/13/2024]
Abstract
Benzophenone-2 (2,2', 4,4'- Tetrahydroxybenzophenone; BP-2) is widely used as a sunscreen in Personal and Care Products (PCPs) for protection against ultraviolet (UV) radiation. The effects of BP-2 on random-sex adult zebrafish (Danio rerio) cytochrome P450 (CYP450) were studied. The main goal was to investigate the detoxification mechanisms underlying the adverse consequences of exposure to xenobiotic chemicals such as BP-2. Total protein content, CYP450 content, and erythromycin N-demethylase (ERND) activity were evaluated as indicators of protein CYP3A expression. Five sets of pooled random-sex adult zebrafish were exposed to 0.0, 0.1, 5.0, and 10.0 mg/L of BP-2 to evaluate their acute and chronic toxicity (4 and 15 days, respectively). ERND activity was significantly increased in the chronic toxicity group compared to that in the control group, whereas CYP450 remained unchanged. The results suggest a sufficiently fast catalytic process that does not alter the total CYP450 content. It implies a mediation of CYP450 3A induction by BP-2 and the pregnane X receptor ligand-binding domain (PXR LBD) interaction. Ligand-protein interactions were confirmed via in silico docking with AutoDock Vina. Further computational studies indicate BP-2 potential binding affinity for the Estrogen receptor alpha ligand binding domain (ERα LBD). These results suggest that CYPs effects may result in significant toxicity in the zebrafish. Our study highlights the importance of studying biomarkers in aquatic organisms to assess xenobiotic exposure and the potential toxicity of UV filters to humans.
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Alhusban M, Pandey P, Ahn J, Avula B, Haider S, Avonto C, Ali Z, Khan SI, Ferreira D, Khan IA, Chittiboyina AG. Computational Tools to Expedite the Identification of Potential PXR Modulators in Complex Natural Product Mixtures: A Case Study with Five Closely Related Licorice Species. ACS OMEGA 2022; 7:26824-26843. [PMID: 35936409 PMCID: PMC9352242 DOI: 10.1021/acsomega.2c03240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
The genus Glycyrrhiza, comprising approximately 36 spp., possesses complex structural diversity and is documented to possess a wide spectrum of biological activities. Understanding and finding the mechanisms of efficacy or safety for a plant-based therapy is very challenging, yet it is crucial and necessary to understand the polypharmacology of traditional medicines. Licorice extract was shown to modulate the xenobiotic receptors, which might manifest as a potential route for natural product-induced drug interactions. However, different mechanisms could be involved in this phenomenon. Since the induced herb-drug interaction of licorice supplements via Pregnane X receptor (PXR) is understudied, we ventured out to analyze the potential modulators of PXR in complex mixtures such as whole extracts by applying computational mining tools. A total of 518 structures from five species of Glycyrrhiza: 183 (G. glabra), 180 (G. uralensis), 100 (G. inflata), 33 (G. echinata), and 22 (G. lepidota) were collected and post-processed to yield 387 unique compounds. Visual inspection of top candidates with favorable ligand-PXR interactions and the highest docking scores were identified. The in vitro testing revealed that glabridin (GG-14) is the most potent PXR activator among the tested compounds, followed by licoisoflavone A, licoisoflavanone, and glycycoumarin. A 200 ns molecular dynamics study with glabridin confirmed the stability of the glabridin-PXR complex, highlighting the importance of computational methods for rapid dereplication of potential xenobiotic modulators in a complex mixture instead of undertaking time-consuming classical biological testing of all compounds in a given botanical.
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Affiliation(s)
- Manal Alhusban
- Department
of BioMolecular Sciences, Division of Pharmacognosy, University of Mississippi, University, Mississippi 38677, United States
| | - Pankaj Pandey
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Jongmin Ahn
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Bharathi Avula
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Saqlain Haider
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Cristina Avonto
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Zulfiqar Ali
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Shabana I. Khan
- Department
of BioMolecular Sciences, Division of Pharmacognosy, University of Mississippi, University, Mississippi 38677, United States
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Daneel Ferreira
- Department
of BioMolecular Sciences, Division of Pharmacognosy, University of Mississippi, University, Mississippi 38677, United States
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Ikhlas A. Khan
- Department
of BioMolecular Sciences, Division of Pharmacognosy, University of Mississippi, University, Mississippi 38677, United States
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
| | - Amar G. Chittiboyina
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
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3
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Parveen A, Alhusban M, Fantoukh OI, Ali Z, Chittiboyina AG, Khan IA, Khan SI. Probing PXR activation and modulation of CYP3A4 by Tinospora crispa and Tinospora sinensis. JOURNAL OF ETHNOPHARMACOLOGY 2022; 291:115159. [PMID: 35245632 PMCID: PMC11094663 DOI: 10.1016/j.jep.2022.115159] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 01/29/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The two Tinospora species, T. crispa and T. sinensis, native to Southeast Asia, are integral components of various traditional preparations with structure-function claims to treat various disorders, including diabetes and inflammation. AIM OF THE STUDY To assure the safety of the botanicals finished products, herb-drug interaction potential of T. crispa and T. sinensis was investigated by testing their extracts and compounds for in vitro activation of the pregnane X-receptor (PXR) and the modulation of CYP3A4 isozyme, selectively. MATERIALS AND METHODS A total of sixteen fully characterized phytochemicals from T. crispa and T. sinensis were evaluated for PXR activation by luciferase reporter gene assay. CYP3A4 inhibition studies were carried out for eleven compounds. In addition, docking studies were performed to elucidate the possible binding modes to the PXR by the compounds using computational methods. RESULTS Significant activation of PXR (2-fold) was observed for both extracts and non-polar fractions of T. crispa. Among the pure compounds, columbin showed highest activation of PXR (3-fold), which was comparable with the positive control, rifampicin. Vital interactions were predicted with docking simulation of PXR-columbin complex with critical amino acid residues (Trp-299) that are known for the activation of PXR. The methanolic extracts of T. crispa and T. sinensis also showed considerable CYP3A4 inhibition. CONCLUSION T. crispa and T. sinensis, both demonstrated the potential to mediate herb-drug interaction through PXR activation and inhibition of CYP3A4 isozyme. Moreover, the elucidation of the potential to induce herb-drug interaction, by the phytochemicals of these Tinospora plants, thereby supports the need for further investigation to establish the clinical relevancy of these constituents for possible adverse interactions with pharmaceutical drugs.
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Affiliation(s)
- Abidah Parveen
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, United States; Division of Pharmacognosy, Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, United States; Department of Pharmaceutical Sciences, Abbottabad University of Science & Technology, Havelian, KPK, Pakistan.
| | - Manal Alhusban
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, United States; Division of Pharmacognosy, Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, United States; Faculty of Pharmacy, Philadelphia University, Amman, Jordan.
| | - Omer I Fantoukh
- Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
| | - Zulfiqar Ali
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, United States.
| | - Amar G Chittiboyina
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, United States.
| | - Ikhlas A Khan
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, United States; Division of Pharmacognosy, Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, United States.
| | - Shabana I Khan
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, United States; Division of Pharmacognosy, Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, United States.
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Rigalli JP, Theile D, Nilles J, Weiss J. Regulation of PXR Function by Coactivator and Corepressor Proteins: Ligand Binding Is Just the Beginning. Cells 2021; 10:cells10113137. [PMID: 34831358 PMCID: PMC8625645 DOI: 10.3390/cells10113137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 12/13/2022] Open
Abstract
The pregnane X receptor (PXR, NR1I2) is a nuclear receptor which exerts its regulatory function by heterodimerization with the retinoid-X-receptor α (RXRα, NR2B1) and binding to the promoter and enhancer regions of diverse target genes. PXR is involved in the regulation of drug metabolism and excretion, metabolic and immunological functions and cancer pathogenesis. PXR activity is strongly regulated by the association with coactivator and corepressor proteins. Coactivator proteins exhibit histone acetyltransferase or histone methyltransferase activity or associate with proteins having one of these activities, thus promoting chromatin decondensation and activation of the gene expression. On the contrary, corepressor proteins promote histone deacetylation and therefore favor chromatin condensation and repression of the gene expression. Several studies pointed to clear cell- and ligand-specific differences in the activation of PXR. In this article, we will review the critical role of coactivator and corepressor proteins as molecular determinants of the specificity of PXR-mediated effects. As already known for other nuclear receptors, understanding the complex mechanism of PXR activation in each cell type and under particular physiological and pathophysiological conditions may lead to the development of selective modulators with therapeutic potential.
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Ramanjulu JM, Williams SP, Lakdawala AS, DeMartino MP, Lan Y, Marquis RW. Overcoming the Pregnane X Receptor Liability: Rational Design to Eliminate PXR-Mediated CYP Induction. ACS Med Chem Lett 2021; 12:1396-1404. [PMID: 34531948 DOI: 10.1021/acsmedchemlett.1c00187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 08/02/2021] [Indexed: 12/26/2022] Open
Abstract
The pregnane X receptor (PXR) regulates expression of proteins responsible for all three phases required for the detoxification mechanism, which include CYP450 enzymes, phase II enzymes, and multidrug efflux pumps. Therefore, PXR is a prominent receptor that is responsible for xenobiotic excretion and drug-drug interactions. Pyrimidinone 1 is an antagonist of the calcium sensing receptor (CaSR) and a strong activator of PXR. Repeat oral administration revealed diminished exposures over time, which prohibited further progression. A medicinal chemistry campaign was initiated to understand and abolish activation of PXR in order to increase systemic exposures. Rational structure-activity relationship investigations utilizing cocrystal structures and a de novo pharmacophore model resulted in compounds devoid of PXR activation. These studies culminated in the first orally active CaSR antagonist 8 suitable for progression. Cocrystallography, the pharmacophore model employed, and additional observations reported herein supported rational elimination of PXR activation and have applicability across diverse chemical classes to help erase PXR-driven drug-drug interactions.
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Affiliation(s)
- Joshi M. Ramanjulu
- GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Shawn P. Williams
- GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Ami S. Lakdawala
- GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Michael P. DeMartino
- GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Yunfeng Lan
- GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Robert W. Marquis
- GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
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6
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Mutation of a single amino acid of pregnane X receptor switches an antagonist to agonist by altering AF-2 helix positioning. Cell Mol Life Sci 2020; 78:317-335. [PMID: 32232515 DOI: 10.1007/s00018-020-03505-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/04/2020] [Accepted: 03/11/2020] [Indexed: 10/24/2022]
Abstract
Pregnane X receptor (PXR) is activated by chemicals to transcriptionally regulate drug disposition and possibly decrease drug efficacy and increase resistance, suggesting therapeutic value for PXR antagonists. We previously reported the antagonist SPA70 and its analog SJB7, which unexpectedly is an agonist. Here, we describe another unexpected observation: mutating a single residue (W299A) within the PXR ligand-binding domain converts SPA70 to an agonist. After characterizing wild-type and W299A PXR activity profiles, we used molecular dynamics simulations to reveal that in wild-type PXR, agonists stabilize the activation function 2 (AF-2) helix in an "inward" position, but SPA70 displaces the AF-2. In W299A, however, SPA70 stabilizes the AF-2 "inward", like agonists. We validated our model by predicting the antagonist SJC2 to be a W299A agonist, which was confirmed experimentally. Our work correlates previously unobserved ligand-induced conformational changes to PXR cellular activity and, for the first time, reveals how PXR antagonists work.
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7
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Lin W, Bwayi M, Wu J, Li Y, Chai SC, Huber AD, Chen T. CITCO Directly Binds to and Activates Human Pregnane X Receptor. Mol Pharmacol 2020; 97:180-190. [PMID: 31882411 PMCID: PMC6978709 DOI: 10.1124/mol.119.118513] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 12/23/2019] [Indexed: 12/12/2022] Open
Abstract
The xenobiotic receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are activated by structurally diverse chemicals to regulate the expression of target genes, and they have overlapping regulation in terms of ligands and target genes. Receptor-selective agonists are, therefore, critical for studying the overlapping function of PXR and CAR. An early effort identified 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime (CITCO) as a selective human CAR (hCAR) agonist, and this has since been widely used to distinguish the function of hCAR from that of human PXR (hPXR). The selectivity was demonstrated in a green monkey kidney cell line, CV-1, in which CITCO displayed >100-fold selectivity for hCAR over hPXR. However, whether the selectivity observed in CV-1 cells also represented CITCO activity in liver cell models was not hitherto investigated. In this study, we showed that CITCO: 1) binds directly to hPXR; 2) activates hPXR in HepG2 cells, with activation being blocked by an hPXR-specific antagonist, SPA70; 3) does not activate mouse PXR; 4) depends on tryptophan-299 to activate hPXR; 5) recruits steroid receptor coactivator 1 to hPXR; 6) activates hPXR in HepaRG cell lines even when hCAR is knocked out; and 7) activates hPXR in primary human hepatocytes. Together, these data indicate that CITCO binds directly to the hPXR ligand-binding domain to activate hPXR. As CITCO has been widely used, its confirmation as a dual agonist for hCAR and hPXR is important for appropriately interpreting existing data and designing future experiments to understand the regulation of hPXR and hCAR. SIGNIFICANCE STATEMENT: The results of this study demonstrate that 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime (CITCO) is a dual agonist for human constitutive androstane receptor (hCAR) and human pregnane X receptor (hPXR). As CITCO has been widely used to activate hCAR, and hPXR and hCAR have distinct and overlapping biological functions, these results highlight the value of receptor-selective agonists and the importance of appropriately interpreting data in the context of receptor selectivity of such agonists.
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Affiliation(s)
- Wenwei Lin
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Monicah Bwayi
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Yongtao Li
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Sergio C Chai
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Andrew D Huber
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee
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8
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Li L, Welch MA, Li Z, Mackowiak B, Heyward S, Swaan PW, Wang H. Mechanistic Insights of Phenobarbital-Mediated Activation of Human but Not Mouse Pregnane X Receptor. Mol Pharmacol 2019; 96:345-354. [PMID: 31436536 PMCID: PMC6701513 DOI: 10.1124/mol.119.116616] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 07/07/2019] [Indexed: 12/12/2022] Open
Abstract
Phenobarbital (PB), a broadly used antiseizure drug, was the first to be characterized as an inducer of cytochrome P450 by activation of the constitutive androstane receptor (CAR). Although PB is recognized as a conserved CAR activator among species via a well-documented indirect activation mechanism, conflicting results have been reported regarding PB regulation of the pregnane X receptor (PXR), a sister receptor of CAR, and the underlying mechanisms remain elusive. Here, we show that in a human CAR (hCAR)-knockout (KO) HepaRG cell line, PB significantly induces the expression of CYP2B6 and CYP3A4, two shared target genes of hCAR and human PXR (hPXR). In human primary hepatocytes and hCAR-KO HepaRG cells, PB-induced expression of CYP3A4 was markedly repressed by genetic knockdown or pharmacological inhibition of hPXR. Mechanistically, PB concentration dependently activates hPXR but not its mouse counterpart in cell-based luciferase assays. Mammalian two-hybrid assays demonstrated that PB selectively increases the functional interaction between the steroid receptor coactivator-1 and hPXR but not mouse PXR. Moreover, surface plasmon resonance binding affinity assay showed that PB directly binds to the ligand binding domain of hPXR (KD = 1.42 × 10-05). Structure-activity analysis further revealed that the amino acid tryptophan-299 within the ligand binding pocket of hPXR plays a key role in the agonistic binding of PB and mutation of tryptophan-299 disrupts PB activation of hPXR. Collectively, these data reveal that PB, a selective mouse CAR activator, activates both hCAR and hPXR, and provide novel mechanistic insights for PB-mediated activation of hPXR.
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Affiliation(s)
- Linhao Li
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (L.L., M.A.W., Z.L., B.M., P.W.S., H.W.); and BioIVT, Halethorpe, Maryland (S.H.)
| | - Matthew A Welch
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (L.L., M.A.W., Z.L., B.M., P.W.S., H.W.); and BioIVT, Halethorpe, Maryland (S.H.)
| | - Zhihui Li
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (L.L., M.A.W., Z.L., B.M., P.W.S., H.W.); and BioIVT, Halethorpe, Maryland (S.H.)
| | - Bryan Mackowiak
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (L.L., M.A.W., Z.L., B.M., P.W.S., H.W.); and BioIVT, Halethorpe, Maryland (S.H.)
| | - Scott Heyward
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (L.L., M.A.W., Z.L., B.M., P.W.S., H.W.); and BioIVT, Halethorpe, Maryland (S.H.)
| | - Peter W Swaan
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (L.L., M.A.W., Z.L., B.M., P.W.S., H.W.); and BioIVT, Halethorpe, Maryland (S.H.)
| | - Hongbing Wang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (L.L., M.A.W., Z.L., B.M., P.W.S., H.W.); and BioIVT, Halethorpe, Maryland (S.H.)
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9
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Chai SC, Lin W, Li Y, Chen T. Drug discovery technologies to identify and characterize modulators of the pregnane X receptor and the constitutive androstane receptor. Drug Discov Today 2019; 24:906-915. [PMID: 30731240 PMCID: PMC6421094 DOI: 10.1016/j.drudis.2019.01.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/27/2018] [Accepted: 01/30/2019] [Indexed: 11/24/2022]
Abstract
The pregnane X receptor (PXR) and the constitutive androstane receptor (CAR) are ligand-activated nuclear receptors (NRs) that are notorious for their role in drug metabolism, causing unintended drug-drug interactions and decreasing drug efficacy. They control the xenobiotic detoxification system by regulating the expression of an array of drug-metabolizing enzymes and transporters that excrete exogenous chemicals and maintain homeostasis of endogenous metabolites. Much effort has been invested in recognizing potential drugs for clinical use that can activate PXR and CAR to enhance the expression of their target genes, and in identifying PXR and CAR inhibitors that can be used as co-therapeutics to prevent adverse effects. Here, we present current technologies and assays used in the quest to characterize PXR and CAR modulators, which range from biochemical to cell-based and animal models.
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Affiliation(s)
- Sergio C Chai
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Wenwei Lin
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Yongtao Li
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Taosheng Chen
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
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10
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Oladimeji PO, Wright WC, Wu J, Chen T. RNA interference screen identifies NAA10 as a regulator of PXR transcription. Biochem Pharmacol 2018; 160:92-109. [PMID: 30566892 DOI: 10.1016/j.bcp.2018.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 12/14/2018] [Indexed: 01/22/2023]
Abstract
The pregnane X receptor (PXR) is a principal xenobiotic receptor crucial in the detection, detoxification, and clearance of toxic substances from the body. PXR plays a vital role in the metabolism and disposition of drugs, and elevated PXR levels contribute to cancer drug resistance. Therefore, to modulate PXR activity and mitigate drug resistance, it is imperative to fully understand its regulation. To this end, we screened a transcription factor siRNA library in pancreatic cancer cells that express high levels of PXR. Through a comprehensive deconvolution process, we identified N-alpha-acetyltransferase 10 (NAA10) as a factor in the transcriptional machinery regulating PXR transcription. Because no one single factor has 100% operational control of PXR transcriptional regulation, our results together with other previous findings suggest that the transcriptional regulation of PXR is complex and that multiple factors contribute to the process including NAA10.
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Affiliation(s)
- Peter O Oladimeji
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
| | - William C Wright
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, United States; Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, United States; Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, Memphis, TN 38163, United States.
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11
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Cherian MT, Chai SC, Wright WC, Singh A, Alexandra Casal M, Zheng J, Wu J, Lee RE, Griffin PR, Chen T. CINPA1 binds directly to constitutive androstane receptor and inhibits its activity. Biochem Pharmacol 2018; 152:211-223. [PMID: 29608908 DOI: 10.1016/j.bcp.2018.03.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 03/28/2018] [Indexed: 01/28/2023]
Abstract
The constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are xenobiotic sensors that regulate the expression of drug-metabolizing enzymes and efflux transporters. CAR activation promotes drug elimination, thereby reducing therapeutic effectiveness, or causes adverse drug effects via toxic metabolites. CAR inhibitors could be used to attenuate these adverse drug effects. CAR and PXR share ligands and target genes, confounding the understanding of the regulation of receptor-specific activity. We previously identified a small-molecule inhibitor, CINPA1, that inhibits CAR (without activating PXR at lower concentrations) by altering CAR-coregulator interactions and reducing CAR recruitment to DNA response elements of regulated genes. However, solid evidence was not presented for the direct binding of CINPA1 to CAR. In this study, we demonstrate direct interaction of CINPA1 with the CAR ligand-binding domain (CAR-LBD) and identify key residues involved in such interactions through a combination of biophysical and computational methods. We found that CINPA1 resides in the ligand-binding pocket to stabilize the CAR-LBD in a more rigid, less fluid state. Molecular dynamics simulations, together with our previously reported docking model, enabled us to predict which CAR residues were critical for interactions with CINPA1. The importance of these residues for CINPA1 binding were then validated by directed mutations and testing the mutant CAR proteins in transcription reporter and coregulatory interaction assays. We demonstrated strong hydrogen bonding of CINPA1 with N165 and H203 and identified other residues involved in hydrophobic contacts with CINPA1. Overall, our data confirm that CINPA1 directly binds to CAR.
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Affiliation(s)
- Milu T Cherian
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Sergio C Chai
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - William C Wright
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, 920 Madison Avenue, Memphis, TN 38163, USA
| | - Aman Singh
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, 920 Madison Avenue, Memphis, TN 38163, USA
| | - Morgan Alexandra Casal
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; School of Pharmacy, University of Pittsburgh, 3501 Terrace Street, Pittsburgh, PA 15213, USA
| | - Jie Zheng
- Department of Molecular Medicine, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Jing Wu
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Richard E Lee
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Patrick R Griffin
- Department of Molecular Medicine, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Taosheng Chen
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, 920 Madison Avenue, Memphis, TN 38163, USA.
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Lin W, Wang YM, Chai SC, Lv L, Zheng J, Wu J, Zhang Q, Wang YD, Griffin PR, Chen T. SPA70 is a potent antagonist of human pregnane X receptor. Nat Commun 2017; 8:741. [PMID: 28963450 PMCID: PMC5622171 DOI: 10.1038/s41467-017-00780-5] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 07/27/2017] [Indexed: 02/06/2023] Open
Abstract
Many drugs bind to and activate human pregnane X receptor (hPXR) to upregulate drug-metabolizing enzymes, resulting in decreased drug efficacy and increased resistance. This suggests that hPXR antagonists have therapeutic value. Here we report that SPA70 is a potent and selective hPXR antagonist. SPA70 inhibits hPXR in human hepatocytes and humanized mouse models and enhances the chemosensitivity of cancer cells, consistent with the role of hPXR in drug resistance. Unexpectedly, SJB7, a close analog of SPA70, is an hPXR agonist. X-ray crystallography reveals that SJB7 resides in the ligand-binding domain (LBD) of hPXR, interacting with the AF-2 helix to stabilize the LBD for coactivator binding. Differential hydrogen/deuterium exchange analysis demonstrates that SPA70 and SJB7 interact with the hPXR LBD. Docking studies suggest that the lack of the para-methoxy group in SPA70 compromises its interaction with the AF-2, thus explaining its antagonism. SPA70 is an hPXR antagonist and promising therapeutic tool.The xenobiotic-activated human pregnane X receptor (hPXR) regulates drug metabolism. Here the authors develop hPXR modulators, which are of potential therapeutic interest and functionally and structurally characterize the antagonist SPA70 and the structurally related agonist SJB7.
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Affiliation(s)
- Wenwei Lin
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105-3678, USA
| | - Yue-Ming Wang
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105-3678, USA
| | - Sergio C Chai
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105-3678, USA
| | - Lili Lv
- Structure Biology, Shanghai Medicilon Inc., Shanghai, 201299, China
| | - Jie Zheng
- Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL, 33458, USA
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105-3678, USA
| | - Qijun Zhang
- Structure Biology, Shanghai Medicilon Inc., Shanghai, 201299, China
| | - Yong-Dong Wang
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105-3678, USA
| | - Patrick R Griffin
- Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL, 33458, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105-3678, USA.
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