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Wong SG, Ramsden D, Dallas S, Fung C, Einolf HJ, Palamanda J, Chen L, Goosen TC, Siu YA, Zhang G, Tweedie D, Hariparsad N, Jones B, Yates PD. Considerations from the Innovation and Quality Induction Working Group in Response to Drug-Drug Interaction Guidance from Regulatory Agencies: Guidelines on Model Fitting and Recommendations on Time Course for In Vitro Cytochrome P450 Induction Studies Including Impact on Drug Interaction Risk Assessment. Drug Metab Dispos 2020; 49:94-110. [DOI: 10.1124/dmd.120.000055] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 10/21/2020] [Indexed: 01/07/2023] Open
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Cellular levels and molecular dynamics simulations of estragole DNA adducts point at inefficient repair resulting from limited distortion of the double-stranded DNA helix. Arch Toxicol 2020; 94:1349-1365. [PMID: 32185416 PMCID: PMC7225201 DOI: 10.1007/s00204-020-02695-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 03/02/2020] [Indexed: 10/25/2022]
Abstract
Estragole, naturally occurring in a variety of herbs and spices, can form DNA adducts after bioactivation. Estragole DNA adduct formation and repair was studied in in vitro liver cell models, and a molecular dynamics simulation was used to investigate the conformation dependent (in)efficiency of N2-(trans-isoestragol-3'-yl)-2'-deoxyguanosine (E-3'-N2-dG) DNA adduct repair. HepG2, HepaRG cells, primary rat hepatocytes and CHO cells (including CHO wild-type and three NER-deficient mutants) were exposed to 50 μM estragole or 1'-hydroxyestragole and DNA adduct formation was quantified by LC-MS immediately following exposure and after a period of repair. Results obtained from CHO cell lines indicated that NER plays a role in repair of E-3'-N2-dG adducts, however, with limited efficiency since in the CHO wt cells 80% DNA adducts remained upon 24 h repair. Inefficiency of DNA repair was also found in HepaRG cells and primary rat hepatocytes. Changes in DNA structure resulting from E-3'-N2-dG adduct formation were investigated by molecular dynamics simulations. Results from molecular dynamics simulations revealed that conformational changes in double-stranded DNA by E-3'-N2-dG adduct formation are small, providing a possible explanation for the restrained repair, which may require larger distortions in the DNA structure. NER-mediated enzymatic repair of E-3'-N2-dG DNA adducts upon exposure to estragole will be limited, providing opportunities for accumulation of damage upon repeated daily exposure. The inability of this enzymatic repair is likely due to a limited distortion of the DNA double-stranded helix resulting in inefficient activation of nucleotide excision repair.
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Burkina V, Rasmussen MK, Oliinychenko Y, Zamaratskaia G. Porcine cytochrome 2A19 and 2E1. Basic Clin Pharmacol Toxicol 2018; 124:32-39. [PMID: 30171805 PMCID: PMC7379952 DOI: 10.1111/bcpt.13121] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/24/2018] [Indexed: 12/21/2022]
Abstract
Cytochrome P450 (CYP) is a major group of enzymes, which conduct Phase I metabolism. Among commonly used animal models, the pig has been suggested as the most suitable model for investigating drug metabolism in human beings. Moreover, porcine CYP2A19 and CYP2E1 are responsible for the biotransformation of both endogenous and exogenous compounds such as 3‐methylindole (skatole), sex hormones and food compounds. However, little is known about the regulation of porcine CYP2A19 and CYP2E1. In this MiniReview, we summarise the current knowledge about the regulation of porcine CYP2A19 and CYP2E1 by environmental, biological and dietary factors. Finally, we reflect on the need for further research, to clarify the interaction between active feed components and the porcine CYP system.
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Affiliation(s)
- Viktoriia Burkina
- Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, University of South Bohemia in Ceske Budejovice, Vodnany, Czech Republic.,Department of Molecular Science, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | | | - Galia Zamaratskaia
- Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, University of South Bohemia in Ceske Budejovice, Vodnany, Czech Republic.,Department of Molecular Science, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Flarakos J, Du Y, Gu H, Wang L, Einolf HJ, Chun DY, Zhu B, Alexander N, Natrillo A, Hanna I, Ting L, Zhou W, Dole K, Sun H, Kovacs SJ, Stein DS, Tanaka SK, Villano S, Mangold JB. Clinical disposition, metabolism and in vitro drug–drug interaction properties of omadacycline. Xenobiotica 2016; 47:682-696. [DOI: 10.1080/00498254.2016.1213465] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
| | - Yancy Du
- Drug Metabolism and Pharmacokinetics and
| | - Helen Gu
- Drug Metabolism and Pharmacokinetics and
| | - Lai Wang
- Drug Metabolism and Pharmacokinetics and
| | | | | | - Bing Zhu
- Drug Metabolism and Pharmacokinetics and
| | | | | | - Imad Hanna
- Drug Metabolism and Pharmacokinetics and
| | - Lillian Ting
- Clinical Pharmacology, Gilead Sciences, Foster City, CA, USA
| | - Wei Zhou
- Drug Metabolism and Pharmacokinetics and
| | - Kiran Dole
- Translational Medicine, Novartis Institutes for Biomedical Research, DMPK, East Hanover, NJ, USA,
| | | | - Steven J. Kovacs
- Translational Medicine, Novartis Institutes for Biomedical Research, DMPK, East Hanover, NJ, USA,
| | - Daniel S. Stein
- Translational Medicine, Novartis Institutes for Biomedical Research, DMPK, East Hanover, NJ, USA,
| | - S. Ken Tanaka
- Paratek Pharmaceuticals, Clinical and Medical Affairs, King of Prussia, PA, USA, and
| | - Stephen Villano
- Paratek Pharmaceuticals, Clinical and Medical Affairs, King of Prussia, PA, USA, and
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Farooq M, Kelly EJ, Unadkat JD. CYP2D6 Is Inducible by Endogenous and Exogenous Corticosteroids. Drug Metab Dispos 2016; 44:750-7. [PMID: 26965986 PMCID: PMC4851303 DOI: 10.1124/dmd.115.069229] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 03/09/2016] [Indexed: 12/21/2022] Open
Abstract
Although cytochrome P450 (CYP) 2D6 has been widely considered to be noninducible on the basis of human hepatocyte studies, in vivo data suggests that it is inducible by endo- and xenobiotics. Therefore, we investigated if the experimental conditions routinely used in human hepatocyte studies may be a confounding factor in the lack of in vitro induction of CYP2D6. Sandwich cultured human hepatocytes (SCHH) were preincubated with or without dexamethasone (100 nM) for 72 hours before incubation with 1μM endogenous (cortisol or corticosterone) or exogenous (dexamethasone or prednisolone) corticosteroids. At 72 hours, CYP2D6 mRNA, protein, and activity were quantified by real-time quantitative polymerase chain reaction, quantitative proteomics, and formation of dextrorphan from dextromethorphan, respectively. In the absence of supplemental dexamethasone, CYP2D6 activity, mRNA, and protein were significantly and robustly (>10-fold) induced by all four corticosteroids. However, this CYP2D6 induction was abolished in cells preincubated with supplemental dexamethasone. These data show, for the first time, that CYP2D6 is inducible in vitro but the routine presence of 100 nM dexamethasone in the culture medium masks this induction. Our cortisol data are in agreement with the clinical observation that CYP2D6 is inducible during the third trimester of pregnancy when the plasma concentrations of cortisol increase to ∼1μM. These findings, if confirmed in vivo, have implications for predicting CYP2D6-mediated drug-drug interactions and call for re-evaluation of regulatory guidelines on screening for CYP2D6 induction by xenobiotics. Our findings also suggest that cortisol may be a causative factor in the in vivo induction of CYP2D6 during pregnancy.
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Affiliation(s)
- Muhammad Farooq
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Edward J Kelly
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Jashvant D Unadkat
- Department of Pharmaceutics, University of Washington, Seattle, Washington
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Posaconazole plasma exposure correlated to intestinal mucositis in allogeneic stem cell transplant patients. Eur J Clin Pharmacol 2016; 72:953-63. [PMID: 27066958 DOI: 10.1007/s00228-016-2057-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/31/2016] [Indexed: 12/21/2022]
Abstract
PURPOSE Low posaconazole plasma concentrations (PPCs) are frequently encountered in allogeneic hematopoietic stem cell transplant (HSCT) patients, due to variable gastrointestinal absorption. In this study, the impact of intestinal mucositis on posaconazole exposure is investigated. PATIENTS AND METHODS A prospective pharmacokinetic study was performed including allogeneic HSCT patients receiving posaconazole prophylaxis with the oral suspension or tablets. Steady state PPCs were determined using high-performance liquid chromatography-fluorescence detection at the day of transplantation (=day 0), day +7, and +14. Citrulline was measured using liquid chromatography-tandem mass spectrometry to evaluate severity of mucositis, at baseline (day -7 or -6), and at day 0, +7 and +14. Additionally, citrulline plasma concentrations and steady state trough PPCs were determined in hematological patients without HSCT or mucositis. RESULTS Thirty-four HSCT patients received posaconazole oral suspension together with 25 cL of Coca Cola, 6 HSCT patients received posaconazole tablets and 33 hematological patients not receiving HSCT received posaconazole oral suspension. The median (interquartile range) average PPC was 0.26 mg/L (0.17-0.43), 0.67 mg/L (0.27-1.38), and 1.08 mg/L (0.96-1.38), with suspension in HSCT patients, suspension in hematological patients and tablets in HSCT patients, respectively. A higher trough PPC was encountered with the oral suspension when citrulline plasma concentrations were above 10 μmol/L compared to values below 10 μmol/L (p < 0.001), whereas for tablets, average PPCs remained high with citrulline plasma concentrations below or above 10 μmol/L (p = 0.64). CONCLUSION Posaconazole tablets should be preferred to suspension in HSCT patients immediately after transplantation to prevent insufficient plasma exposure due to intestinal mucositis.
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Hackbart KS, Cunha PM, Meyer RK, Wiltbank MC. Effect of glucocorticoid-induced insulin resistance on follicle development and ovulation. Biol Reprod 2013; 88:153. [PMID: 23616591 DOI: 10.1095/biolreprod.113.107862] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Polycystic ovarian syndrome (PCOS) is characterized by hyperandrogenemia, polycystic ovaries, and menstrual disturbance and a clear association with insulin resistance. This research evaluated whether induction of insulin resistance, using dexamethasone (DEX), in a monovular animal model, the cow, could produce an ovarian phenotype similar to PCOS. In all of these experiments, DEX induced insulin resistance in cows as shown by increased glucose, insulin, and HOMA-IR (homeostasis model assessment of insulin resistance). Experiment 1: DEX induced anovulation (zero of five DEX vs. four of four control cows ovulated) and decreased circulating estradiol (E2). Experiment 2: Gonadotropin-releasing hormone (GnRH) was administered to determine pituitary and follicular responses during insulin resistance. GnRH induced a luteinizing hormone (LH) surge and ovulation in both DEX (seven of seven) and control (seven of seven) cows. Experiment 3: E2 was administered to determine hypothalamic responsiveness after induction of an E2 surge in DEX (eight of eight) and control (eight of eight) cows. An LH surge was induced in control (eight of eight) but not DEX (zero of eight) cows. All control (eight of eight) but only two of eight DEX cows ovulated within 60 h of E2 administration. Experiment 4: Short-term DEX was initiated 24 h after induced luteal regression to determine if DEX could acutely block ovulation before peak insulin resistance was induced, similar to progesterone (P4). All control (five of five), no P4-treated (zero of six), and 50% of DEX-treated (three of six) cows ovulated by 96 h after luteal regression. All anovular cows had reduced circulating E2. These data are consistent with DEX creating a lesion in hypothalamic positive feedback to E2 without altering pituitary responsiveness to GnRH or ovulatory responsiveness of follicles to LH. It remains to be determined if the considerable insulin resistance and the reduced follicular E2 production induced by DEX had any physiological importance in the induction of anovulation.
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Affiliation(s)
- Katherine S Hackbart
- Department of Dairy Science, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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PharmGKB summary: very important pharmacogene information for cytochrome P-450, family 2, subfamily A, polypeptide 6. Pharmacogenet Genomics 2013; 22:695-708. [PMID: 22547082 DOI: 10.1097/fpc.0b013e3283540217] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Bjornsson TD, Callaghan JT, Einolf HJ, Fischer V, Gan L, Grimm S, Kao J, King SP, Miwa G, Ni L, Kumar G, McLeod J, Obach SR, Roberts S, Roe A, Shah A, Snikeris F, Sullivan JT, Tweedie D, Vega JM, Walsh J, Wrighton SA. The Conduct of In Vitro and In Vivo Drug-Drug Interaction Studies: A PhRMA Perspective. J Clin Pharmacol 2013. [DOI: 10.1177/0091270003252519] [Citation(s) in RCA: 201] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Matsunaga T, Maruyama M, Matsubara T, Nagata K, Yamazoe Y, Ohmori S. Mechanisms of CYP3A induction by glucocorticoids in human fetal liver cells. Drug Metab Pharmacokinet 2012; 27:653-7. [PMID: 22673009 DOI: 10.2133/dmpk.dmpk-12-nt-018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human fetal liver (HFL) cells express major drug metabolic enzymes CYP3A4, CYP3A5 and CYP3A7. In the fetal hepatocytes, betamethasone and dexamethasone (DEX) markedly enhanced the expression levels of CYP3A4 and CYP3A7 mRNAs and slightly increased the expression level of CYP3A5 mRNA. Interestingly, a high correlation between the CYP3A induction ability and the intensity of anti-inflammatory effect was observed. Human glucocorticoid receptor (GR)-small interfering RNA clearly attenuated the expression level of GR mRNA, and diminished the DEX-stimulated CYP3A4, CYP3A5 and CYP3A7 expression in HFL cells. These findings indicate that GR mediates the induction of CYP3A4 and CYP3A7 expression in human fetal hepatocytes as well as the CYP3A5.
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Black MB, Budinsky RA, Dombkowski A, Cukovic D, LeCluyse EL, Ferguson SS, Thomas RS, Rowlands JC. Cross-species comparisons of transcriptomic alterations in human and rat primary hepatocytes exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Sci 2012; 127:199-215. [PMID: 22298810 DOI: 10.1093/toxsci/kfs069] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A toxicogenomics approach was used to qualitatively and quantitatively compare the gene expression changes in human and rat primary hepatocytes exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Hepatocytes from five individual rats and five individual humans were exposed for 24 h to 11 concentrations of TCDD ranging from 0.00001 to 100nM and a vehicle control. Gene expression changes were analyzed using whole-genome microarrays containing 13,002 orthologs. Significant changes in expression of individual orthologs at any concentration (fold change [FC] ± 1.5 and false discovery rate < 0.05) were higher in the rat (1547) compared with human hepatocytes (475). Only 158 differentially expressed orthologs were common between rats and humans. Enrichment analysis was performed on the differentially expressed orthologs in each species with 49 and 34 enriched human and rat pathways, respectively. Only 12 enriched pathways were shared between the two species. The results demonstrate significant cross-species differences in expression at both the gene and pathway level. Benchmark dose analysis of gene expression changes showed an average 18-fold cross-species difference in potency among differentially expressed orthologs with the rat more sensitive than the human. Similar cross-species differences in potency were observed for signaling pathways. Using the maximum FC in gene expression as a measure of efficacy, the human hepatocytes showed on average a 20% lower efficacy among the individual orthologs showing differential expression. The results provide evidence for divergent cross-species gene expression changes in response to TCDD and are consistent with epidemiological and clinical evidence showing humans to be less sensitive to TCDD-induced hepatotoxicity.
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Affiliation(s)
- Michael B Black
- The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709, USA
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Elsherbiny ME, Brocks DR. The ability of polycyclic aromatic hydrocarbons to alter physiological factors underlying drug disposition. Drug Metab Rev 2011; 43:457-75. [DOI: 10.3109/03602532.2011.596204] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Kim J, Peraire C, Solà J, Johanning KM, Dalton JT, Veverka KA. Drug interaction potential of toremifene andN-desmethyltoremifene with multiple cytochrome P450 isoforms. Xenobiotica 2011; 41:851-62. [DOI: 10.3109/00498254.2011.590546] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Regulation of drug-metabolizing enzymes by xenobiotic receptors: PXR and CAR. Adv Drug Deliv Rev 2010; 62:1238-49. [PMID: 20727377 DOI: 10.1016/j.addr.2010.08.006] [Citation(s) in RCA: 272] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 08/09/2010] [Accepted: 08/10/2010] [Indexed: 12/24/2022]
Abstract
Drug-metabolizing enzymes (DMEs) and transporters play pivotal roles in the disposition and detoxification of numerous foreign and endogenous chemicals. To accommodate chemical challenges, the expression of many DMEs and transporters is up-regulated by a group of ligand-activated transcription factors namely nuclear receptors (NRs). The importance of NRs in xenobiotic metabolism and clearance is best exemplified by the most promiscuous xenobiotic receptors: pregnane X receptor (PXR, NR1I2) and constitutive androstane/activated receptor (CAR, NR1I3). Together, these two receptors govern the inductive expression of a largely overlapping array of target genes encoding phase I and II DMEs, and drug transporters. Moreover, PXR and CAR also represent two distinctive mechanisms of NR activation, whereby CAR demonstrates both constitutive and ligand-independent activation. In this review, recent advances in our understanding of PXR and CAR as xenosensors are discussed with emphasis placed on the differences rather than similarities of these two xenobiotic receptors in ligand recognition and target gene regulation.
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Maezawa K, Matsunaga T, Takezawa T, Kanai M, Ohira S, Ohmori S. Cytochrome P450 3As gene expression and testosterone 6 beta-hydroxylase activity in human fetal membranes and placenta at full term. Biol Pharm Bull 2010; 33:249-54. [PMID: 20118548 DOI: 10.1248/bpb.33.249] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Expression levels of cytochrome P450 (CYP) 3A4, CYP3A5 and CYP3A7 mRNAs in placentas and fetal membranes, which were split into amnion and chorion leave attached decidua (chorion/decidua), obtained from pregnant women with normal delivery (5 subjects) and Caesarean section (15 subjects) were determined. These CYP3A mRNAs were also expressed in amnion and chorion/decidua together with placenta, although the expression level of these mRNAs was strikingly different between subjects. The expression level of the CYP3A4 mRNA in the placenta was about 2-fold higher than those in amnion and chorion/decidua. On the other hand, the expression levels of CYP3A5 and CYP3A7 mRNAs were highest in chorion/decidua. The immunologically related protein(s) with CYP3A7 was detected in all tissues examined. Testosterone 6beta-hydroxylase activity in homogenate of human placenta, amnion and chorion/decidua were 26.6, 3.7 and 4.6 pmol/h/mg protein, respectively. These results suggest that CYP3As in fetal membranes have the metabolic function to protect the fetus from exposure to drugs.
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Affiliation(s)
- Kayoko Maezawa
- Department of Pharmacy, Shinshu University Hospital, 3-1-1 Asahi, Matsumoto 390-8621, Japan
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Budinsky RA, LeCluyse EL, Ferguson SS, Rowlands JC, Simon T. Human and rat primary hepatocyte CYP1A1 and 1A2 induction with 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, and 2,3,4,7,8-pentachlorodibenzofuran. Toxicol Sci 2010; 118:224-35. [PMID: 20705892 DOI: 10.1093/toxsci/kfq238] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The concentration dose response for aryl hydrocarbon receptor (AHR)-mediated CYP1A1 and CYP1A2 messenger RNA (mRNA) induction and enzyme activity was determined in primary cultures of rat and human hepatocytes for 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,4,7,8-pentachlorodibenzofuran, and 2,3,7,8-tetrachlorodibenzofuran. Eleven different congener concentrations from 0.00001 to 100 nM were used, thus spanning seven orders of magnitude. The Hill model was used to obtain values of EC(x) and maximal response from the individual data sets. No-observed effect concentration values were derived using several statistical methods including Dunnett's test, the Welch-Aspin test, and step-down bilinear regression. Thresholds were estimated using baseline projection methods and a "hockey stick" fitting method. Human hepatocytes were less responsive and less sensitive with respect to CYP1A1 activity and mRNA induction than rats. On the other hand, the human CYP1A2 response was more robust than the response in rats but generally less sensitive. These data allow an evaluation of relative species sensitivities for developing interspecies toxicodynamic adjustment factors, for assessing AHR activation thresholds, and for evaluating relative congener potencies. Overall, these data support the position that humans are less sensitive than rats to these AHR-dependent end points and support the use of a data-derived adjustment factor of 1.0 or less for extrapolating between rats and humans.
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Zhou SF, Wang B, Yang LP, Liu JP. Structure, function, regulation and polymorphism and the clinical significance of human cytochrome P450 1A2. Drug Metab Rev 2010; 42:268-354. [PMID: 19961320 DOI: 10.3109/03602530903286476] [Citation(s) in RCA: 183] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Human CYP1A2 is one of the major CYPs in human liver and metabolizes a number of clinical drugs (e.g., clozapine, tacrine, tizanidine, and theophylline; n > 110), a number of procarcinogens (e.g., benzo[a]pyrene and aromatic amines), and several important endogenous compounds (e.g., steroids). CYP1A2 is subject to reversible and/or irreversible inhibition by a number of drugs, natural substances, and other compounds. The CYP1A gene cluster has been mapped on to chromosome 15q24.1, with close link between CYP1A1 and 1A2 sharing a common 5'-flanking region. The human CYP1A2 gene spans almost 7.8 kb comprising seven exons and six introns and codes a 515-residue protein with a molecular mass of 58,294 Da. The recently resolved CYP1A2 structure has a relatively compact, planar active site cavity that is highly adapted for the size and shape of its substrates. The architecture of the active site of 1A2 is characterized by multiple residues on helices F and I that constitutes two parallel substrate binding platforms on either side of the cavity. A large interindividual variability in the expression and activity of CYP1A2 has been observed, which is largely caused by genetic, epigenetic and environmental factors (e.g., smoking). CYP1A2 is primarily regulated by the aromatic hydrocarbon receptor (AhR) and CYP1A2 is induced through AhR-mediated transactivation following ligand binding and nuclear translocation. Induction or inhibition of CYP1A2 may provide partial explanation for some clinical drug interactions. To date, more than 15 variant alleles and a series of subvariants of the CYP1A2 gene have been identified and some of them have been associated with altered drug clearance and response and disease susceptibility. Further studies are warranted to explore the clinical and toxicological significance of altered CYP1A2 expression and activity caused by genetic, epigenetic, and environmental factors.
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Affiliation(s)
- Shu-Feng Zhou
- Discpline of Chinese Medicine, School of Health Sciences, RMIT University, Bundoora, Victoria 3083, Australia.
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Nishimura M. [Evaluation of induction of drug-metabolizing enzyme mRNAs in primary cultures of cryopreserved human and cynomolgus monkey hepatocytes]. YAKUGAKU ZASSHI 2009; 129:815-20. [PMID: 19571516 DOI: 10.1248/yakushi.129.815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We introduce a method for measuring drug-metabolizing enzymes and transporters using real-time one-step RT-PCR with TaqMan probes. This method has the advantages of high sensitivity, simplicity, and linearity of quantification over a wide range of mRNA concentrations, making it particularly suitable for evaluating large numbers of samples, as required in expression profile determinations. We also introduce the use of primary cultures of cryopreserved human and cynomolgus monkey hepatocytes as an enzyme induction model. Furthermore, we introduce the combination of real-time one-step RT-PCR and hepatocytes for evaluating the potency of various drugs in inducing drug-metabolizing enzymes and transporters. We discuss the usefulness of evaluating the gene induction of drug-metabolizing enzymes and transporters following exposure to drugs in human and cynomolgus monkey hepatocytes. The combination of real-time one-step RT-PCR and primary cultures of cryopreserved hepatocytes is useful for preclinical drug evaluation and for screening to evaluate the induction potency of new drug candidates.
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Affiliation(s)
- Masuhiro Nishimura
- New Product and Business Development, Research and Development Center, Otsuka Pharmaceutical Factory, Inc., Tokushima, Japan.
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Abstract
The molecular genetics of nicotine metabolism involves multiple polymorphic catalytic enzymes. Variation in metabolic pathways results in nicotine disposition kinetics that differ between individuals and ethnic groups. Twin studies indicate that a large part of this variance is genetic in origin, although environmental influences also contribute. The primary aim of this chapter is to review the current knowledge regarding the genetic variability in the enzymes that metabolize nicotine in humans. The focus is on describing the genetic polymorphisms that exist in cytochromes P450 (CYPs), aldehyde oxidase 1 (AOX1), UDP-glucuronosyltransferases (UGTs), and flavin-containing monooxygenase 3 (FMO3). Genetic studies have demonstrated that polymorphisms in CYP2A6, the primary enzyme responsible for nicotine breakdown, make a sizable contribution to the wide range of nicotine metabolic capacity observed in humans. Thus, special attention will be given to CYP2A6, because slower nicotine metabolism requires less frequent self-administration, and accordingly influences smoking behaviors. In addition, the molecular genetics of nicotine metabolism in nonhuman primates, mice, and rats will be reviewed briefly.
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Affiliation(s)
- Jill C Mwenifumbo
- Centre for Addiction & Mental Health and Department of Pharmacology, University of Toronto, Toronto, ON, Canada
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McGinnity DF, Zhang G, Kenny JR, Hamilton GA, Otmani S, Stams KR, Haney S, Brassil P, Stresser DM, Riley RJ. Evaluation of Multiple in Vitro Systems for Assessment of CYP3A4 Induction in Drug Discovery: Human Hepatocytes, Pregnane X Receptor Reporter Gene, and Fa2N-4 and HepaRG Cells. Drug Metab Dispos 2009; 37:1259-68. [DOI: 10.1124/dmd.109.026526] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Abstract
Nicotine underlies tobacco addiction, influences tobacco use patterns, and is used as a pharmacological aid to smoking cessation. The absorption, distribution and disposition characteristics of nicotine from tobacco and medicinal products are reviewed. Nicotine is metabolized primarily by the liver enzymes CYP2A6, UDPglucuronosyltransferase (UGT), and flavin-containing monooxygenase (FMO). In addition to genetic factors, nicotine metabolism is influenced by diet and meals, age, sex, use of estrogen-containing hormone preparations, pregnancy and kidney disease, other medications, and smoking itself. Substantial racial/ethnic differences are observed in nicotine metabolism, which are likely influenced by both genetic and environmental factors. The most widely used biomarker of nicotine intake is cotinine, which may be measured in blood, urine, saliva, hair, or nails. The current optimal plasma cotinine cut-point to distinguish smokers from non-smokers in the general US population is 3 ng ml(-1). This cut-point is much lower than that established 20 years ago, reflecting less secondhand smoke exposure due to clear air policies and more light or occasional smoking.
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Affiliation(s)
- Neal L Benowitz
- Division of Clinical Pharmacology and Experimental Therapeutics, University of California, San Francisco, P. O. Box 1220, San Francisco, CA 94143-1220, USA.
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22
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Kenny JR, Chen L, McGinnity DF, Grime K, Shakesheff KM, Thomson B, Riley R. Efficient assessment of the utility of immortalized Fa2N-4 cells for cytochrome P450 (CYP) induction studies using multiplex quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and substrate cassette methodologies. Xenobiotica 2008; 38:1500-17. [DOI: 10.1080/00498250802495846] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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23
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Olinga P, Elferink MGL, Draaisma AL, Merema MT, Castell JV, Pérez G, Groothuis GMM. Coordinated induction of drug transporters and phase I and II metabolism in human liver slices. Eur J Pharm Sci 2008; 33:380-9. [PMID: 18328680 DOI: 10.1016/j.ejps.2008.01.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 01/18/2008] [Accepted: 01/19/2008] [Indexed: 11/26/2022]
Abstract
Although regulation of phase I drug metabolism in human liver is relatively well studied, the regulation of phase II enzymes and of drug transporters is incompletely characterized. Therefore, we used human liver slices to investigate the PXR, CAR and AhR-mediated induction of drug transporters and phase I and II metabolic enzymes. Precision-cut human liver slices were incubated for 5 or 24h with prototypical inducers: phenobarbital (PB) (50 microM) for CAR, beta-naphthoflavone (BNF) (25 microM) for AhR, and rifampicin (RIF) (10 microM) for PXR, and gene expression of the phase I enzymes CYP1A1, 1A2, 3A4, 3A5, 2B6, 2A6, the phase II enzymes UGT1A1 and 1A6, and the transporters MRP2, MDR1, BSEP, NTCP and OATP8 was measured. BNF induced CYP1A1, UGT1A1 and UGT1A6 and MRP2, NTCP and MDR1. RIF induced CYP3A4, 3A5, 2B6, 2A6, UGT1A1, UGT1A6 and BSEP, MRP2 and MDR1 and slightly downregulated OATP8. PB induced CYP3A4, 3A5, 2B6 and 2A6, UGT1A1 and all transporters. Large interindividual differences were found with respect to the level of induction. Enzyme activity of CYP3A4, measured by testosterone metabolism, was increased after 24h by RIF. 7-Ethoxycoumarin O-deethylation activity, mediated predominantly by CYP 1A1/1A2 but also by other CYPs, was increased after 24h with PB. We have shown that regulation of all phases of the (in)activation of a drug via the CAR, AhR and the PXR pathways can be studied in human liver slices. The concomitant induction of metabolic enzymes and transporters shows that also in the human liver transporters and metabolic enzymes are regulated coordinately.
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Affiliation(s)
- P Olinga
- Department of Pharmacokinetics and Drug Delivery, Groningen Research Institute for Pharmacy, University of Groningen, Ant. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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Hewitt NJ, Lecluyse EL, Ferguson SS. Induction of hepatic cytochrome P450 enzymes: methods, mechanisms, recommendations, and in vitro-in vivo correlations. Xenobiotica 2008; 37:1196-224. [PMID: 17968743 DOI: 10.1080/00498250701534893] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Induction of drug-clearance pathways (Phase 1 and 2 enzymes and transporters) can have important clinical consequences. Inducers can (1) increase the clearance of other drugs, resulting in a decreased therapeutic effect, (2) increase the activation of pro-drugs, causing an alteration in their efficacy and pharmacokinetics, and (3) increase the bioactivation of drugs that contribute to hepatotoxicity via reactive intermediates. Nuclear receptors are key mediators of drug-induced changes in the expression of drug-clearance pathways. However, species differences in nuclear receptor activation make the prediction of cytochrome P450 (CYP) induction in humans from data derived from animal models problematic. Thus, in vitro human-relevant model systems are increasingly used to evaluate enzyme induction. In this review, the authors' current understanding of the mechanisms of enzyme induction and the in vitro methods for assessing the induction potential of new drugs will be discussed. Relevant issues and considerations surrounding proper study design and the interpretation of in vitro results will be discussed in light of the current US Food and Drug Administration (FDA) recommendations.
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Affiliation(s)
- N J Hewitt
- CellzDirect, 480 Hillsboro Street, Suite 130, Pittsboro, NC 27312, USA.
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25
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Maruyama M, Matsunaga T, Harada E, Ohmori S. Comparison of basal gene expression and induction of CYP3As in HepG2 and human fetal liver cells. Biol Pharm Bull 2007; 30:2091-7. [PMID: 17978482 DOI: 10.1248/bpb.30.2091] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human fetal liver (HFL) cell culture was initiated from a pool of six normal human liver tissues. The proliferation and viability of HFL cells were evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay, and the cells increased by more than 100-fold by culture for 15 d. The levels of expression of albumin (ALB), hepatocyte nuclear factor 4alpha, hepatocyte growth factor, CYP3A4, CYP3A5, and CYP3A7 mRNAs in HFL cells increased with culture period, while that of alpha-fetoprotein (AFP) mRNA decreased gradually. In HepG2 cells, however, the expression levels of ALB and AFP mRNAs were not changed, and the levels of expression of CYP3A4, CYP3A5, and CYP3A7 mRNAs decreased gradually. The mRNA expression of major CYP isoforms including CYP3As, i.e., CYP1A2, CYP2A6, CYP2B6, CYP2C (2C9 and 2C19), CYP2D6, and CYP2E1, could be detected in HepG2 cells. With the exception of CYP1A2, all of the CYP mRNAs expressed in HepG2 cells were detected in HFL cells. In HFL cells, CYP3A4 and CYP3A7 mRNA expression levels were markedly up-regulated by dexamethasone (DEX), but not by rifampicin (RIF). CYP3A5 mRNA expression was increased to a level 3-fold greater than control by DEX. On the other hand, CYP3A4, CYP3A5, and CYP3A7 mRNA expression levels in HepG2 cells were increased from 2- to 3-fold by treatment with DEX and RIF. Pregnane X receptor mRNA was expressed in HepG2 cells, but not HFL cells. These results indicate that the character of HFL cells with regard to CYP expression was different from that of HepG2 cells.
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Affiliation(s)
- Masataka Maruyama
- Department of Pharmacy, Shinshu University Hospital, 3-1-1 Asahi, Matsumoto, Japan
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26
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Vasiluk L, Pinto LJ, Tsang WS, Gobas FAPC, Eickhoff C, Moore MM. The uptake and metabolism of benzo[a]pyrene from a sample food substrate in an in vitro model of digestion. Food Chem Toxicol 2007; 46:610-8. [PMID: 17959292 DOI: 10.1016/j.fct.2007.09.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 08/23/2007] [Accepted: 09/04/2007] [Indexed: 11/28/2022]
Abstract
Food ingestion is the major route of exposure to many hydrophobic organic contaminants (HOCs) such as benzo[a]pyrene (BaP). It has been proposed that food-bound HOCs may become bioavailable after their mobilization by gastrointestinal fluids. The purpose of this research was to measure the uptake efficiency of [(14)C]-BaP bound to skim milk powder using an in vitro model of gastrointestinal digestion followed by sorption to human enterocytes (Caco-2 cells). Neutralization of intestinal fluids released [(14)C]-BaP into the soluble fraction. Ageing of benzo[a]pyrene onto skim milk for 6 months significantly decreased the mobilized fraction but did not affect the amount of benzo[a]pyrene taken up into Caco-2 cells. Hence, significant differences in aqueous phase concentrations may not always be reflected in significant differences in uptake. We obtained evidence that the digestion/uptake of skim milk lipids is accompanied by the diffusive uptake of BaP (the fat flush hypothesis) as trans-cellular transfer of BaP was favoured in the apical to basolateral direction. These data support the theory that non-polar substances including HOCs are preferentially transferred from the lumen into the bloodstream and provide indirect evidence that the uptake is related to the fugacity gradient created by the unidirectional uptake of dietary lipids.
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Affiliation(s)
- Luba Vasiluk
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
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27
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Kieran MW, Packer RJ, Onar A, Blaney SM, Phillips P, Pollack IF, Geyer JR, Gururangan S, Banerjee A, Goldman S, Turner CD, Belasco JB, Broniscer A, Zhu Y, Frank E, Kirschmeier P, Statkevich P, Yver A, Boyett JM, Kun LE. Phase I and pharmacokinetic study of the oral farnesyltransferase inhibitor lonafarnib administered twice daily to pediatric patients with advanced central nervous system tumors using a modified continuous reassessment method: a Pediatric Brain Tumor Consortium Study. J Clin Oncol 2007; 25:3137-43. [PMID: 17634493 DOI: 10.1200/jco.2006.09.4243] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE A dose-escalation phase I and pharmacokinetic study of the farnesyltransferase inhibitor lonafarnib (SCH66336) was conducted in children with recurrent or progressive CNS tumors. Primary objectives were to estimate the maximum-tolerated dose (MTD) and to describe the dose-limiting toxicities (DLTs) and pharmacokinetics of lonafarnib. Farnesylation inhibition of HDJ-2 in peripheral blood was also measured. PATIENTS AND METHODS Lonafarnib was administered orally twice daily at dose levels of 70, 90, 115, 150, and 200 mg/m2/dose bid. A modified continual reassessment method (CRM) was used to estimate the MTD based on actual dosages of lonafarnib administered and toxicities observed during the initial 4 weeks of treatment. RESULTS Fifty-three children with progressive or recurrent brain tumors were enrolled, with a median age of 12.2 years (range, 3.9 to 19.5 years). Dose-limiting pneumonitis or myelosuppression was observed in three of three patients at the 200 mg/m2/dose level. A relatively constant DLT rate at the 70, 90, and 115 mg/m2/dose levels resulted in a recommended phase II dose of 115 mg/m2/dose. Significant diarrhea did not occur with prophylactic loperamide. Both radiographic response (one anaplastic astrocytoma) and stable disease (one medulloblastoma, two high-grade and four low-grade gliomas, one ependymoma, and one sarcoma) were noted, and seven patients remained on treatment for 1 year or longer. CONCLUSION Although the estimated MTD by the CRM model was 98.5 mg/m2/dose, because of the relatively constant observed DLT rate at the lower four dose levels, the recommended phase II dose of lonafarnib is 115 mg/m2/dose administered twice daily by mouth with concurrent loperamide.
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Affiliation(s)
- Mark W Kieran
- Dana-Farber Cancer Institute and Children's Hospital Boston, Boston, MA 02115, USA.
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Poyck PPC, Hoekstra R, Chhatta A, Bloemendaal LT, van Wijk ACWA, Galavotti D, van Gulik TM, Chamuleau RAFM. Time-related analysis of metabolic liver functions, cellular morphology, and gene expression of hepatocytes cultured in the bioartificial liver of the Academic Medical Center in Amsterdam (AMC-BAL). ACTA ACUST UNITED AC 2007; 13:1235-46. [PMID: 17518723 DOI: 10.1089/ten.2006.0343] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A comprehensive understanding of the mechanisms that underlie hepatic differentiation inside a bioartificial liver (BAL) device is obtained when functional, histological, and gene expression analyses can be combined. We therefore developed a novel cell-sampling technique that enabled us to analyze adherent hepatocytes inside a BAL device during a 5-day culture period, without the necessity of terminating the culture. Biochemical data showed that hepatocyte-specific functions were relatively stable, despite an increase in glycolytic activity. Quantitative reverse transcriptase polymerase chain reaction analysis of hepatic genes cytochrome p450 3A29, albumin, glutamine synthetase, alpha-1 antitrypsin, and carbamoyl-phosphate synthetase, but also de-differentiation marker pi-class glutathione S transferase showed stable messenger ribonucleic acid (mRNA) levels from day 1 to 5. In contrast, mRNA levels of alpha-fetoprotein, pro- and anti-apoptotic genes Bax-alpha and Bcl-X(L), metabolic genes lactate dehydrogenase and uncoupling protein 2, and cytoskeleton genes alpha- and beta-tubulin and beta-actin increased in 5 days. Histological analysis revealed viable tissue-like structures with adaptation to the in vitro environment. We conclude that hepatocytes show a tendency for de-differentiation shortly after seeding but thereafter remain acceptably differentiated during 5 days of culture. Furthermore, partly impaired mitochondrial function is suggestive for local hypoxic regions and may trigger the observed metabolic changes. Anti-apoptotic activity seems to balance pro-apoptotic activity. This new cell-sampling technique facilitates the analysis of dynamic processes of hepatocyte culture inside a BAL.
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Affiliation(s)
- Paul P C Poyck
- Department of Surgery (Surgical Laboratory), Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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29
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Hewitt NJ, Lechón MJG, Houston JB, Hallifax D, Brown HS, Maurel P, Kenna JG, Gustavsson L, Lohmann C, Skonberg C, Guillouzo A, Tuschl G, Li AP, LeCluyse E, Groothuis GMM, Hengstler JG. Primary hepatocytes: current understanding of the regulation of metabolic enzymes and transporter proteins, and pharmaceutical practice for the use of hepatocytes in metabolism, enzyme induction, transporter, clearance, and hepatotoxicity studies. Drug Metab Rev 2007; 39:159-234. [PMID: 17364884 DOI: 10.1080/03602530601093489] [Citation(s) in RCA: 523] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review brings you up-to-date with the hepatocyte research on: 1) in vitro-in vivo correlations of metabolism and clearance; 2) CYP enzyme induction, regulation, and cross-talk using human hepatocytes and hepatocyte-like cell lines; 3) the function and regulation of hepatic transporters and models used to elucidate their role in drug clearance; 4) mechanisms and examples of idiosyncratic and intrinsic hepatotoxicity; and 5) alternative cell systems to primary human hepatocytes. We also report pharmaceutical perspectives of these topics and compare methods and interpretations for the drug development process.
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Affiliation(s)
- Nicola J Hewitt
- Scientific Writing Services, Wingertstrasse, Erzhausen, Germany.
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Nishimura M, Koeda A, Suzuki E, Kawano Y, Nakayama M, Satoh T, Narimatsu S, Naito S. Regulation of mRNA expression of MDR1, MRP1, MRP2 and MRP3 by prototypical microsomal enzyme inducers in primary cultures of human and rat hepatocytes. Drug Metab Pharmacokinet 2007; 21:297-307. [PMID: 16946557 DOI: 10.2133/dmpk.21.297] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mRNA induction of various transporters by rifampicin (Rif), dexamethasone (Dex) and omeprazole (Ome) was investigated in primary cultures of cryopreserved human and rat hepatocytes. Analysis was performed by quantitative real-time RT-PCR using primers and TaqMan probes. In primary cultures of human hepatocytes, mRNA levels of MDR and MRP1 were increased by about 1.5 fold and 1.3 fold, respectively, by exposure to Rif at 2 to 50 microM as compared with 0.1% DMSO-treated controls. MRP2 mRNA levels in the same human hepatocytes were significantly increased by 1.2 to 1.8 fold by exposure to Rif at 50 microM as compared with controls. In primary cultures of rat hepatocytes, Mdr1a and Mdr1b mRNA levels were not increased or only slightly increased at 24 hr by exposure to any of the inducers at 2, 10 or 50 microM. Mrp2 mRNA levels in the same rat hepatocytes were significantly increased by 7 to 45 fold by exposure to Dex at 2 microM as compared with controls. Based on the species differences observed in the present study, primary cultures of cryopreserved hepatocytes from both the human and rat should be useful in preclinical drug development for evaluating candidate drugs for transporter induction.
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Affiliation(s)
- Masuhiro Nishimura
- Department of Drug Metabolism, Division of Pharmacology, Drug Safety and Metabolism, Otsuka Pharmaceutical Factory Inc., Naruto, Tokushima, Japan.
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Svoboda M, Thalhammer T, Aust S, Arrich F, Assadian O, Toma CD. Estrogen sulfotransferase (SULT1E1) expression in benign and malignant human bone tumors. J Surg Oncol 2007; 95:572-81. [PMID: 17230544 DOI: 10.1002/jso.20748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND AND OBJECTIVES 17beta-estradiol regulates growth and differentiation in normal and malignant bone. E2 is inactivated to 17beta-estradiol-sulfate through estrogen sulfotransferase (SULT1E1). RESULTS In an explorative study, SULT1E1 mRNA expression was assessed in a broad range of samples from benign, primary and secondary malignant bone tumors. We detected SULT1E1 mRNA in 31/50 tumor samples (10/19 malignant, 6/13 benign tumors; 15/18 metastases). Significantly more SULT1E1-positive samples were found in metastases than in primary bone tumors (P = 0.019). Yet, there was no difference between malignant and benign primary tumors (P = 0.718). SULT1E1 mRNA levels were not related to patients' age, gender, tumor location, stage, grading, and chemotherapy pretreatment. Relative SULT1E1 mRNA levels did not correlate with that of estrogen-receptor alpha (ERalpha) as assessed by quantitative TaqMan PCR (10 malignant, 8 benign tissue samples). In the latter, ERalpha mRNA, but not SULT1E1 mRNA levels were significantly lower than in the malignant samples (P = 0.006 and P = 0.71, respectively). Also, pronounced expression of SULT1E1 mRNA but not of ERalpha mRNA was observed in osteosarcoma (MG-63, HOS) and Ewing's sarcoma (TC-71) cells, while human osteoblasts and BMSC contained ERalpha but not SULT1E1 mRNA. CONCLUSION Frequent expression of SULT1E1 mRNA in various human bone tumors suggests that sulfonation might be important to control E2 levels and activity.
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Affiliation(s)
- Martin Svoboda
- Department of Pathophysiology, Center for Physiology and Pathophysiology, Medical University of Vienna, Vienna, Austria
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32
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Hewitt NJ, de Kanter R, LeCluyse E. Induction of drug metabolizing enzymes: a survey of in vitro methodologies and interpretations used in the pharmaceutical industry--do they comply with FDA recommendations? Chem Biol Interact 2006; 168:51-65. [PMID: 17239835 DOI: 10.1016/j.cbi.2006.12.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Revised: 12/14/2006] [Accepted: 12/15/2006] [Indexed: 09/30/2022]
Abstract
The FDA has published guidelines by which to carry out and interpret in vitro induction studies using hepatocytes but do researchers in pharmaceutical companies actually follow these to the letter? In a survey of 30 participants in the pharmaceutical industry, 19 questions were posed regarding the species investigated, methodologies and interpretations of the data. Also addressed was the in-house decision making processes as a result of in vitro induction data. The survey showed that, although the basic methods were similar, no two researchers carried out and interpreted induction assays in exactly the same way. No single method was superior but all included enzyme activities as the major end point. Hepatocytes from animal species were used to confirm animal in vivo data but only human hepatocytes were used to predict human induction responses. If a compound was found to be positive in an in vitro induction assay, few would halt the development of the compound. The majority would consider other properties of the compound (bioavailability, clearance and therapeutic concentrations) and follow the FDA recommendation to conduct clinical drug-drug interaction studies. Overall, the results from this survey indicate that there is no standard pharmaceutical industry method or evaluation criterion by which in vitro assays are carried out. Rather than adhering to the FDA guidelines, some adapt methods and interpretation according to their own experience and need (whether screening or lead optimisation). There was general consensus that studies using human hepatocyte cultures currently provide the best indication of the in vivo induction potential of NCEs. In addition, the assessment of in vitro induction data from the literature suggest that the two-fold induction threshold and the percent of positive control criteria may not be the best methods to accurately assess the in vivo induction potential of a drug. Although the two-fold induction criterion is now obsolete, more predictive models for determining the clinical induction potential are needed. Alternative models are proposed and discussed herein.
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Persson KP, Ekehed S, Otter C, Lutz ESM, McPheat J, Masimirembwa CM, Andersson TB. Evaluation of Human Liver Slices and Reporter Gene Assays as Systems for Predicting the Cytochrome P450 Induction Potential of Drugs in Vivo in Humans. Pharm Res 2006; 23:56-69. [PMID: 16328606 DOI: 10.1007/s11095-005-8812-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Accepted: 09/28/2005] [Indexed: 01/29/2023]
Abstract
PURPOSE The aim of the study was to investigate the feasibility of predicting human in vivo cytochrome P450 (CYP) induction properties of drugs using in vitro methods. METHODS The CYP induction potential of compounds was tested in human liver slices and in reporter gene assays for the aryl hydrocarbon receptor (AhR) and the pregnane X receptor (PXR). RESULTS In human liver slices, CYP activities decreased dramatically over the experimental period, whereas mRNA levels could reliably be used to investigate CYP1A, 2C9, and 3A4 induction. However, the interindividual variations and demanding experimentation limit the use of liver slices in screening programs. Reporter gene assays are robust and reliable assays, amenable to high throughput screening. Several compounds activated AhR. The relevance of this activation, however, needs to be further investigated since there are no clear reports on drugs inducing CYP1A in vivo. The results from the PXR assay could be used to correctly classify compounds with known CYP3A induction properties when relating in vivo AUCtot to PXR EC50 values. CONCLUSIONS Liver slices are a valuable model to study the regulation of a larger number of enzymes by single compounds. The PXR reporter gene assay could be used as a reliable screening method to predict CYP3A induction in vivo.
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Affiliation(s)
- Kajsa P Persson
- DMPK & Bioanalytical Chemistry, AstraZeneca R&D Mölndal, 431 83, Mölndal, Sweden.
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McGinnity DF, Berry AJ, Kenny JR, Grime K, Riley RJ. EVALUATION OF TIME-DEPENDENT CYTOCHROME P450 INHIBITION USING CULTURED HUMAN HEPATOCYTES. Drug Metab Dispos 2006; 34:1291-300. [PMID: 16679385 DOI: 10.1124/dmd.106.009969] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Primary human hepatocytes in culture are commonly used to evaluate cytochrome P450 (P450) induction via an enzyme activity endpoint. However, other processes can confound data interpretation. To this end, the impact of time-dependent P450 inhibition in this system was evaluated. Using a substrate-cassette approach, P450 activities were determined after incubation with the prototypic inhibitors tienilic acid (CYP2C9), erythromycin, troleandomycin, and fluoxetine (CYP3A4). Kinetic analysis of enzyme inactivation in hepatocytes was used to describe the effect of these time-dependent inhibitors and derive the inhibition parameters kinact and KI) which generally were in good agreement with the values derived using recombinant P450s and human liver microsomes (HLMs). Tienilic acid selectively inhibited CYP2C9-dependent diclofenac 4'-hydroxylation activity, and erythromycin, troleandomycin, and fluoxetine inhibited CYP3A4-dependent midazolam 1'-hydroxylation in a time- and concentration-dependent manner. Fluoxetine also inhibited CYP2C19-dependent S-mephenytoin 4'-hydroxylation in a time- and concentration-dependent manner in hepatocytes, HLMs, and recombinant CYP2C19 (KI 0.4 microM and kinact 0.5 min(-1)). As expected, the effect of fluoxetine on CYP2D6 in hepatocytes was consistent with potent yet reversible inhibition. A very weak time-dependent CYP2C9 inhibitor (AZ1, a proprietary AstraZeneca compound; KI 30 microM and kinact 0.02 min(-1)) effectively abolished CYP2C9 activity over 24 h at low (micromolar) concentrations in primary cultured human hepatocytes. This work demonstrates that caution is warranted in the interpretation of enzyme induction studies with metabolically stable, weak time-dependent inhibitors, which may have dramatic inhibitory effects on P450 activity in this system. Therefore, in addition to enzyme activity, mRNA and/or protein levels should be measured to fully evaluate the P450 induction potential of a drug candidate.
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Affiliation(s)
- Dermot F McGinnity
- Department of Physical & Metabolic Science, AstraZeneca R&D Charnwood, Bakewell Road, Loughborough, Leicestershire, LE11 5RH, UK.
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35
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Gillberg M, Skaanild MT, Friis C. Regulation of Gender-Dependent CYP2A Expression in Pigs: Involvement of Androgens and CAR. Basic Clin Pharmacol Toxicol 2006; 98:480-7. [PMID: 16635107 DOI: 10.1111/j.1742-7843.2006.pto_261.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The expression of drug metabolizing cytochrome P4502A (CYP2A) is highly gender-dependent in minipigs with the highest activity in females. In other species, orthologs of CYP2A have been shown to be under the regulation of nuclear receptor constitutive androstane receptor, whereas little is known about regulation in pigs. To investigate the effect of sex hormones on porcine cytochrome P450 CYP2A and CYP3A expression was assessed in liver samples taken before and after castration of sexually mature minipig boars. Removal of the primary androgen source resulted in significant increases of CYP2A mRNA, protein and enzyme activity levels. Likewise, expression of CYP3A was increased, although to a lesser extent. To examine the involvement of constitutive androstane receptor in the regulation of CYP2A, primary porcine hepatocytes were exposed to modulators of murine constitutive androstane receptor and human constitutive androstane receptor activity. The CYP2A activity was significantly increased by exposure to phenobarbital, an indirect activator of constitutive androstane receptor, and the human constitutive androstane receptor-ligand CITCO. In contrast, no effect was seen following exposure to the potent murine constitutive androstane receptor-ligand TCPOBOP and the hormonal murine constitutive androstane receptor-ligands androstenol and oestrone. Thus, the results support that 1) porcine CYP2A is reversibly inhibited by androgens on a transcriptional basis in vivo; 2) the induction profile of CYP2A in vitro shares similarity with that of human constitutive androstane receptor-regulated CYPs, indicating an involvement of a porcine constitutive androstane receptor in the regulation of CYP2A.
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Affiliation(s)
- Mette Gillberg
- Department of Veterinary Pathobiology, Laboratory of Toxicology, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
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36
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Haberl M, Anwald B, Klein K, Weil R, Fuss C, Gepdiremen A, Zanger UM, Meyer UA, Wojnowski L. Three haplotypes associated with CYP2A6 phenotypes in Caucasians. Pharmacogenet Genomics 2005; 15:609-24. [PMID: 16041240 DOI: 10.1097/01.fpc.0000171517.22258.f1] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The human cytochrome P450 2A6 (CYP2A6) enzyme metabolizes several xenobiotic compounds of clinical or toxicological importance. We aimed to identify genetic variants and major CYP2A6 haplotypes associated with CYP2A6 phenotypic variation. CYP2A6 mRNA level, protein level, activity and haplotypes were determined in Caucasian liver samples via real-time polymerase chain reaction, Western blot, coumarin 7-hydroxylation, DNA sequencing and genotyping, respectively. Phenotypes were then analyzed for associations with haplotypes. CYP2A6 transcript, protein and activity levels were correlated among each other. In 45 African-American, 156 Caucasian, 47 Chinese, 50 Japanese and 47 Korean DNA samples, we detected 95 different polymorphisms in the CYP2A6 gene, 49 of which had not been described previously. Caucasian variants formed 33 haplotypes which built four clades. Allele *9B and the CYP2A7/2A6 partial deletion allele CYP2A6*12B were both associated with decreased expression. The latter haplotype extends at least over 147 kb up into the CYP2B6 gene. A haplotype almost identical to allele *1A was associated with decreased expression and activity of CYP2A6 compared to all other haplotypes. In summary A CYP2A6*1A-like allele, *9B and *12B are major genetic determinants of CYP2A6 phenotype variation in Caucasians.
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Roymans D, Annaert P, Van Houdt J, Weygers A, Noukens J, Sensenhauser C, Silva J, Van Looveren C, Hendrickx J, Mannens G, Meuldermans W. Expression and induction potential of cytochromes P450 in human cryopreserved hepatocytes. Drug Metab Dispos 2005; 33:1004-16. [PMID: 15802389 DOI: 10.1124/dmd.104.003046] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fresh human hepatocytes are still considered as the "gold standard" to screen in vitro for cytochrome P450 (P450) induction. However, sparse availability of good quality human liver tissue for research purposes and the demand for standardized cell populations, together with the need for proper storage of the cells not immediately required, have resulted in the development of cryopreservation techniques that provide adequate viability and plateability of hepatocytes after thawing. This study aimed at validating cryopreserved human hepatocytes as a model to investigate P450 induction. Cryopreserved cells from four different donors were plated and cultured for 48 h, followed by incubation in the presence of typical P450 inducers. During the experiments, quality of the cultured cells was monitored both physiologically and morphologically. Concomitantly, the activity of CYP1A2, 2B6, 2C9, 2E1, and 3A4 was measured together with their mRNA and protein expression. Determination of CYP1A2, 2B6, 2C9, 2E1, and 3A4 activity in control versus prototypical inducer-treated hepatocytes revealed a maximal significant mean 11.6-, 2.8-, 1.9-, 1.5-, and 9.0-fold induction over their basal expression, respectively. Protein expression analysis of these P450s confirmed these results. Moreover, a mean 44.9-, 3.5-, 3.2-, and 13.8-fold induction of CYP1A2, 2B6, 2C9, and 3A4 mRNA was observed. Our data demonstrate that cryopreserved human hepatocytes are a valuable tool to study the induction of CYP1A2, 2B6, 2C9, 2E1, and 3A4.
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Affiliation(s)
- Dirk Roymans
- Preclinical Pharmacokinetics, Johnson & Johnson Pharmaceutical Research & Development, Beerse, Belgium.
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Abstract
Nicotine is of importance as the addictive chemical in tobacco, pharmacotherapy for smoking cessation, a potential medication for several diseases, and a useful probe drug for phenotyping cytochrome P450 2A6 (CYP2A6). We review current knowledge about the metabolism and disposition kinetics of nicotine, some other naturally occurring tobacco alkaloids, and nicotine analogs that are under development as potential therapeutic agents. The focus is on studies in humans, but animal data are mentioned when relevant to the interpretation of human data. The pathways of nicotine metabolism are described in detail. Absorption, distribution, metabolism, and excretion of nicotine and related compounds are reviewed. Enzymes involved in nicotine metabolism including cytochrome P450 enzymes, aldehyde oxidase, flavin-containing monooxygenase 3, amine N-methyltransferase, and UDP-glucuronosyltransferases are represented, as well as factors affecting metabolism, such as genetic variations in metabolic enzymes, effects of diet, age, gender, pregnancy, liver and kidney diseases, and racial and ethnic differences. Also effects of smoking and various inhibitors and inducers, including oral contraceptives, on nicotine metabolism are discussed. Due to the significance of the CYP2A6 enzyme in nicotine clearance, special emphasis is given to the effects and population distributions of CYP2A6 alleles and the regulation of CYP2A6 enzyme.
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Affiliation(s)
- Janne Hukkanen
- Division of Clinical Pharmacology and Experimental Therapeutics, Medical Service, San Francisco Genreral Hospital Medical Center, and the Department of Medicine, University of California, San Francisco, Box 1220, San Francisco, CA 94143-1220, USA
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Nishimura M, Yokoi T, Tateno C, Kataoka M, Takahashi E, Horie T, Yoshizato K, Naito S. Induction of Human CYP1A2 and CYP3A4 in Primary Culture of Hepatocytes from Chimeric Mice with Humanized Liver. Drug Metab Pharmacokinet 2005; 20:121-6. [PMID: 15855724 DOI: 10.2133/dmpk.20.121] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Chimeric mice with near-completely humanized liver were constructed by transplantating hepatocytes from a Japanese and Caucasian donor. In the present study, we investigated the induction of human CYP1A2 and CYP3A4 mRNA in a primary culture of the cryopreserved chimeric mouse hepatocytes. beta-naphthoflavone (beta-NF) and rifampicin (Rif) were used as typical cytochrome P450 (CYP) inducers for CYP1A2 and CYP3A4, respectively. Analysis was performed by the real-time reverse-transcription polymerase chain reaction method. CYP1A2 mRNA in the primary culture of chimeric mouse hepatocytes in mice No. 1, 2, and 3 was significantly increased 3.8-, 6.3-, and 3.3-fold by 5 microM beta-NF exposure, respectively, compared with the 0.1% DMSO treated control (p<0.01). CYP3A4 mRNA in the primary culture of chimeric mouse hepatocytes in mice No. 1, 2, and 3 was significantly increased 8.4-fold (p<0.001), 2.2-fold (p<0.01), and 2.3-fold (p<0.05) by 50 microM Rif exposure, respectively, compared with the 0.1% DMSO treated control. The present study demonstrated that a primary culture of cryopreserved hepatocytes from chimeric mice with humanized liver could be used for evaluating the induction of drug metabolizing enzymes in human. This in vitro method may be a useful method for screening the induction potency of new drug candidates on drug metabolizing enzymes.
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Affiliation(s)
- Masuhiro Nishimura
- Division of Pharmacology, Drug Safety and Metabolism, Otsuka Pharmaceutical Factory, Inc., Naruto, Tokushima 772-8601, Japan
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Prueksaritanont T, Richards KM, Qiu Y, Strong-Basalyga K, Miller A, Li C, Eisenhandler R, Carlini EJ. Comparative Effects of Fibrates on Drug Metabolizing Enzymes in Human Hepatocytes. Pharm Res 2005; 22:71-8. [PMID: 15771232 DOI: 10.1007/s11095-004-9011-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
PURPOSE The induction potential of different fibric acid derivatives on human drug metabolizing enzymes was evaluated to help assess the role of enzyme induction on pharmacokinetic drug interactions. METHODS Effects of gemfibrozil, fenofibric acid, and clofibric acid on expression levels of cytochromes P450 (CYPs) 3A4 and 2C8 and UDP-glucuronyltransferase (UGT) 1A1 were evaluated in primary human hepatocyte cultures. The potential for these fibrates to activate human pregnane X receptor (PXR) also was studied in a cell-based PXR reporter gene assay. RESULTS All three fibrates caused increases in mRNA levels of CYP3A4 (2- to 5-fold), CYP2C8 (2- to 6-fold), and UGT1A1 (2- to 3-fold). On average, the effects on CYP3A4 were less than (< or =30% of rifampin), while those on CYP2C8 and UGT1A1 were comparable to or slightly higher than (up to 200% of rifampin) the corresponding effects observed with rifampin (10 microM). Consistent with the mRNA results, all fibrates caused moderate (approximately 2- to 3-fold) increases in CYP3A4 activity (measured by testosterone 6beta hydroxylase), as compared to about a 10-fold increase by rifampin. Significant increases (3- to 6-fold) in amodiaquine N-deethylase (a functional probe for CYP2C8 activity) also were observed with clofibric acid, fenofibric acid, and rifampin, in agreement with the mRNA finding. However, in contrast to the mRNA induction, marked decreases (>60%) in CYP2C8 activity were obtained with gemfibrozil treatment. Consistent with this finding, co-incubation of amodiaquine with gemfibrozil, but not with fenofibric acid, clofibric acid, or rifampin, in human liver microsomes or hepatocytes resulted in significantly decreased amodiaquine N-deethylase activity (IC50 = 80 microM for gemfibrozil, >500 microM for fenofibric or clofibric acid, and >50 microM for rifampin). Similar to rifampin, all three fibrates caused a modest change in the glucuronidation of chrysin, a nonspecific substrate of UGTs. No significant activation on human pregnane X receptor (PXR) was observed with the three fibrates in a PXR reporter gene assay. CONCLUSIONS In human hepatocytes, both fenofibric acid and clofibric acid are inducers of CYP3A4 and CYP2C8. Gemfibrozil is also an inducer of CYP3A4, but acts as both an inducer and an inhibitor of CYP2C8. In this system, all fibrates are weak inducers of UGT1A1. The enzyme inducing effects of fibrates appear to be mediated via a mechanism(s) other than PXR activation. These results suggest that fibrates may have potential to cause various pharmacokinetic drug interactions via their differential effects on enzyme induction and/or inhibition.
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Drobná Z, Waters SB, Walton FS, LeCluyse EL, Thomas DJ, Stýblo M. Interindividual variation in the metabolism of arsenic in cultured primary human hepatocytes. Toxicol Appl Pharmacol 2004; 201:166-77. [PMID: 15541756 DOI: 10.1016/j.taap.2004.05.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2004] [Accepted: 05/12/2004] [Indexed: 11/26/2022]
Abstract
Liver is a prime site for conversion of inorganic arsenic (iAs) to methylated metabolites, including methylarsenicals (MAs) and dimethylarsenicals (DMAs). To assess interindividual variation in the capacity of liver to metabolize iAs, we examined the metabolic fate of arsenite (iAs(III)) in normal primary human hepatocytes obtained from eight donors and cultured under standard conditions. Methylation rates, yields, and distribution of arsenicals were determined for hepatocytes exposed to 0.3-30 nmol of iAs(III)/mg of protein for 24 h. Although the accumulation of arsenic (As) by cells was a linear function of the initial concentration of iAs(III) in culture, the concentration of As retained in cells varied several fold among donors. DMAs was the major methylated metabolite found in cultures exposed to low concentrations of iAs(III); at higher concentrations, MAs was always predominant. Maximal rates for methylation of iAs(III) were usually attained at 3 or 9 nmol of iAs(III)/mg of protein and varied about 7-fold among donors. For most donors, the methylation rate decreased at the highest iAs(III) concentrations. MAs was the major methylated metabolite retained in cells regardless of exposure level. DMAs was the major methylated metabolite found in medium. The interindividual differences in rates for iAs(III) methylation were not strictly associated with variations in basal mRNA levels for cyt19, an As-methyltransferase. Analysis of the coding sequence of cyt19 identified one heterozygote with Met287Thr mutation in a single allele. Thus, genetic polymorphism of cyt19 along with other cellular factors is likely responsible for interindividual differences in the capacity of primary human hepatocytes to retain and metabolize iAs(III).
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Affiliation(s)
- Zuzana Drobná
- Department of Pediatrics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Donato MT, Serralta A, Jiménez N, Pérez G, Castell JV, Mir J, Gómez-Lechón MJ. LIVER GRAFTS PRESERVED IN CELSIOR SOLUTION AS SOURCE OF HEPATOCYTES FOR DRUG METABOLISM STUDIES: COMPARISON WITH SURGICAL LIVER BIOPSIES. Drug Metab Dispos 2004; 33:108-14. [PMID: 15448115 DOI: 10.1124/dmd.104.001545] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Suitability of human liver grafts preserved in Celsior solution (CS) for preparing metabolically competent hepatocyte cultures has been examined. To this end, basal and induced activity and mRNA levels of major hepatic cytochrome P450 (P450) enzymes have been measured. By 24 h in culture, measurable levels of the 10 P450 mRNAs studied were found in all hepatocyte preparations examined, with CYP2E1, CYP2C9, and CYP3A4 mRNAs being the most abundant. Compared with hepatocytes obtained from surgical liver resections (SLRs), lower content of each P450 mRNA was found in hepatocytes from the CS group; however, the relative distribution of individual P450 mRNAs was similar. Similar results were observed after measuring P450 activities. CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2E1, and CYP3A4 activities in hepatocytes from CS-flushed grafts were lower than but comparable with those of cultures prepared from SLRs. No differences in the metabolite profile of testosterone were found. Treatment of hepatocytes from CS-preserved grafts with model P450 inducers shows that 2 microM methylcholanthrene only increased CYP1A1 and CYP1A2 mRNAs (>100-fold over control), 1 mM phenobarbital markedly increased CYP2A6, CYP2B6, and CYP3A4 mRNA content (>7-fold), and 50 microM rifampicin highly increased CYP3A4 mRNA levels (>10-fold), whereas minor effects (<3-fold) were observed in CYP2A6, CYP2B6, and CYP2C9 mRNAs. This induction pattern of P450s was similar, in terms of magnitude, reproducibility, and specificity, to that shown in primary hepatocytes from surgical biopsies. Overall, our results indicate that, cold-preserved in CS, liver grafts constitute a valuable source of human hepatocytes for drug metabolism studies.
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Affiliation(s)
- M Teresa Donato
- Unidad de Hepatología Experimental, Hospital Universitario La Fe, Avda Campanar 21, 46009 Valencia, Spain.
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Christian K, Lang M, Maurel P, Raffalli-Mathieu F. Interaction of heterogeneous nuclear ribonucleoprotein A1 with cytochrome P450 2A6 mRNA: implications for post-transcriptional regulation of the CYP2A6 gene. Mol Pharmacol 2004; 65:1405-14. [PMID: 15155834 DOI: 10.1124/mol.65.6.1405] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human xenobiotic-metabolizing enzyme cytochrome P450, CYP2A6, catalyzes the bioactivation of a number of carcinogens and drugs and is overexpressed in cases of liver diseases, such as cirrhosis, viral hepatitis, and parasitic infestation, and in certain tumor cells. This suggests that CYP2A6 may be a major liver catalyst in pathological conditions. In the present study, we have addressed molecular mechanisms underlying the regulation of the CYP2A6 gene. We present evidence of several proteins present in human hepatocytes that interact specifically with the 3'-untranslated region (UTR) of CYP2A6 mRNA. Biochemical and immunological evidence show that the RNA-protein complex of highest intensity contains the heterogeneous nuclear ribonucleoprotein (hnRNP) A1 or a closely related protein. Mapping of the hnRNP A1 binding site within CYP2A6 3'-UTR reveals that the smallest portion of RNA supporting significant binding consists of 111 central nucleotides of the 3'-UTR. Our studies also indicate that hnRNPA1 from HepG2 cancer cells exhibits modified binding characteristics to the CYP2A6 3'-UTR compared with primary hepatocytes. We found that the level of CYP2A6 mRNA remains high in conditions of impaired transcription in primary human hepatocytes, showing that CYP2A6 expression can be affected post-transcriptionally in conditions of cellular stress. Our results indicate that the post-transcriptional regulation involves interaction of the hnRNP A1 protein with CYP2A6 mRNA. The present data suggest that hnRNPA1 is a critical regulator of expression of the human CYP2A6 gene and support the notion that this P450 isoform may be of particular significance in stressed human liver cells.
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Affiliation(s)
- Kyle Christian
- Department of Pharmaceutical Biosciences, Division of Biochemistry, Uppsala University, Uppsala, Sweden
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Mills JB, Rose KA, Sadagopan N, Sahi J, de Morais SMF. Induction of drug metabolism enzymes and MDR1 using a novel human hepatocyte cell line. J Pharmacol Exp Ther 2004; 309:303-9. [PMID: 14722322 DOI: 10.1124/jpet.103.061713] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Induction of drug-metabolizing enzymes and transporters can cause drug-drug interactions and loss of efficacy. In vitro induction studies traditionally use primary hepatocyte cultures and enzyme activity with selected marker compounds. We investigated the use of a novel human hepatocyte clone, the Fa2N-4 cell line, as an alternative reagent, which is readily available and provides a consistent, reproducible system. We used the Invader assay to monitor gene expression in these cells. This assay is a robust, yet simple, high-throughput system for quantification of mRNA transcripts. CYP1A2, CYP3A4, CYP2C9, UGT1A, and MDR1 transcripts were quantified from total RNA extracts from Fa2N-4 cells treated with a panel of known inducers and compared with vehicle controls. In addition, we used enzyme activity assays to monitor the induction of CYP1A2, CYP2C9, and CYP3A4. The Fa2N-4 cells responded in a similar manner as primary human hepatocytes. Treatment with 10 microM rifampin resulted in increases in CYP3A4 mRNA (17-fold) and activity (6-beta-hydroxytestoterone formation, 9-fold); and in CYP2C9 mRNA (4-fold) and activity (4'-hydroxydiclofenac formation, 2-fold). Treatment with 50 microM beta-naphthoflavone resulted in increases in CYP1A2 mRNA (15-fold) and activity (7-ethoxyresorufin O-dealkylation, 27-fold). UGT1A mRNA was induced by beta-naphthoflavone (2-fold), and MDR1 (P-glycoprotein) mRNA was induced by rifampin (3-fold). These preliminary data using a few prototypical inducers show that Fa2N-4 cells can be a reliable surrogate for primary human hepatocytes, and, when used in conjunction with the Invader technology, could provide a reliable assay for assessment of induction of drug-metabolizing enzymes and transporters.
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Affiliation(s)
- Jessica B Mills
- Pfizer Global Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT 06340, USA
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Nishimura M, Ueda N, Naito S. Effects of dimethyl sulfoxide on the gene induction of cytochrome P450 isoforms, UGT-dependent glucuronosyl transferase isoforms, and ABCB1 in primary culture of human hepatocytes. Biol Pharm Bull 2003; 26:1052-6. [PMID: 12843640 DOI: 10.1248/bpb.26.1052] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the gene expression of GAPDH, cytochrome P450 isoforms (CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2E1, CYP3A4, CYP3A5, and CYP3A7), UGT-dependent glucuronosyl transferase isoforms (UGT1A6 and UGT1A9), and ABC transporter (ABCB1) after exposure to 0.1, 0.5, and 2.5% dimethyl sulfoxide (DMSO). GAPDH mRNA levels after exposure were less than 2 times higher or lower than control levels at all DMSO concentrations. CYP1A1, CYP1B1, CYP2A6, CYP2E1, CYP3A4, CYP3A5, CYP3A7, and UGT1A9 mRNA levels were less than 2 times higher or lower than control levels at 0.1% and 0.5% DMSO. CYP1A2, UGT1A6, and ABCB1 mRNA levels were less than 2 times higher or lower than control levels at all DMSO concentrations. CYP2E1 and CYP3A4 mRNA levels were 2.5-3.2 times and 2.0-3.3 times higher than control levels at 2.5% DMSO, respectively. UGT1A9 mRNA levels were 0.2-0.5 times lower than control levels at 2.5% DMSO. Exposure to beta-naphthoflavone reduced CYP1A1 mRNA levels in a concentration-dependent manner for donors 1 and 2. Exposure to beta-naphthoflavone reduced CYP1A2 mRNA levels in a concentration-dependent manner for all donors. However, exposure to beta-naphthoflavone increased CYP1B1 mRNA levels for donors 2 and 3 at 2.5% DMSO. Exposure to rifampicin reduced CYP3A4 mRNA levels for all donors at 0.5% and 2.5% DMSO. Exposure to rifampicin also reduced CYP3A5 and CYP3A7 mRNA levels for donors 1 and 3 at 0.5% and 2.5% DMSO. In conclusion, a DMSO concentration of 0.1% or less may be appropriate for studying induction after drug exposure.
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Affiliation(s)
- Masuhiro Nishimura
- Division of Pharmacology, Drug Safety and Metabolism, Otsuka Pharmaceutical Factory, Inc., Naruto, Tokushima, Japan.
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Bjornsson TD, Callaghan JT, Einolf HJ, Fischer V, Gan L, Grimm S, Kao J, King SP, Miwa G, Ni L, Kumar G, McLeod J, Obach RS, Roberts S, Roe A, Shah A, Snikeris F, Sullivan JT, Tweedie D, Vega JM, Walsh J, Wrighton SA. The conduct of in vitro and in vivo drug-drug interaction studies: a Pharmaceutical Research and Manufacturers of America (PhRMA) perspective. Drug Metab Dispos 2003; 31:815-32. [PMID: 12814957 DOI: 10.1124/dmd.31.7.815] [Citation(s) in RCA: 547] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Current regulatory guidances do not address specific study designs for in vitro and in vivo drug-drug interaction studies. There is a common desire by regulatory authorities and by industry sponsors to harmonize approaches, to allow for a better assessment of the significance of findings across different studies and drugs. There is also a growing consensus for the standardization of cytochrome P450 (P450) probe substrates, inhibitors and inducers and for the development of classification systems to improve the communication of risk to health care providers and to patients. While existing guidances cover mainly P450-mediated drug interactions, the importance of other mechanisms, such as transporters, has been recognized more recently, and should also be addressed. This article was prepared by the Pharmaceutical Research and Manufacturers of America (PhRMA) Drug Metabolism and Clinical Pharmacology Technical Working Groups and represents the current industry position. The intent is to define a minimal best practice for in vitro and in vivo pharmacokinetic drug-drug interaction studies targeted to development (not discovery support) and to define a data package that can be expected by regulatory agencies in compound registration dossiers.
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Albright CD, Salganik RI, Craciunescu CN, Mar MH, Zeisel SH. Mitochondrial and microsomal derived reactive oxygen species mediate apoptosis induced by transforming growth factor-beta1 in immortalized rat hepatocytes. J Cell Biochem 2003; 89:254-61. [PMID: 12704789 DOI: 10.1002/jcb.10498] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transforming growth factor-beta1 (TGFbeta1) is a multifunctional cytokine that is over expressed during liver hepatocytes injury and regeneration. SV40-transformed CWSV-1 rat hepatocytes that are p53-defective undergo apoptosis in response to choline deficiency (CD) or TGFbeta1, which mediates CD-apoptosis. Reactive oxygen species (ROS) are essential mediators of apoptosis. We have shown that apoptosis induced by TGFbeta1 is accompanied by ROS generation and the ROS-trapping agent N-acetylcysteine (NAC) inhibits TGFbeta1-induced apoptosis. While persistent induction of ROS contributes to this form of apoptosis, the source of ROS generated downstream of TGFbeta1 is not clear. The mitochondria and the endoplasmic reticulum both harbor potent electron transfer chains that might be the source of ROS essential for completion of TGFbeta1-apoptosis. Here we show that CWSV-1 cells treated with cyclosporine A, which prevents opening of mitochondrial membrane pores required for ROS generation, inhibits TGFbeta1-induced apoptosis. A similar effect was obtained by treating these cells with rotenone, an inhibitor of complex 1 of the mitochondrial electron transfer chain. However, we demonstrate that TGFbeta1 induces cytochrome P450 1A1 and that metyrapone, a potent inhibitor of cytochrome P450 1A1, inhibits TGFbeta1-induced apoptosis. Therefore, our studies indicate that concurrent with promoting generation of ROS from mitochondria, TGFbeta1 also promotes generation of ROS from the cytochrome P450 electron transfer chain. Since inhibition of either of these two sources of ROS interferes with apoptosis, it is reasonable to conclude that the combined involvement of both pathways is essential for completion of TGFbeta1-induced apoptosis.
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Affiliation(s)
- Craig D Albright
- Department of Nutrition, School of Public Health and School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7400, USA
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Madan A, Graham RA, Carroll KM, Mudra DR, Burton LA, Krueger LA, Downey AD, Czerwinski M, Forster J, Ribadeneira MD, Gan LS, LeCluyse EL, Zech K, Robertson P, Koch P, Antonian L, Wagner G, Yu L, Parkinson A. Effects of prototypical microsomal enzyme inducers on cytochrome P450 expression in cultured human hepatocytes. Drug Metab Dispos 2003; 31:421-31. [PMID: 12642468 DOI: 10.1124/dmd.31.4.421] [Citation(s) in RCA: 254] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cultured human hepatocytes are a valuable in vitro system for evaluating new molecular entities as inducers of cytochrome P450 (P450) enzymes. The present study summarizes data obtained from 62 preparations of cultured human hepatocytes that were treated with vehicles (saline or dimethylsulfoxide, 0.1%), beta-naphthoflavone (33 microM), phenobarbital (100 or 250 microM), isoniazid (100 microM) and/or rifampin (20 or 50 microM), and examined for the expression of P450 enzymes based on microsomal activity toward marker substrates, or in the case of CYP2C8, the level of immunoreactive protein. The results show that CYP1A2 activity was markedly induced by beta-naphthoflavone (on average 13-fold, n = 28 preparations), and weakly induced by phenobarbital (1.9-fold, n = 25) and rifampin (2.3-fold, n = 22); CYP2A6 activity tended to be increased with phenobarbital (n = 7) and rifampin (n = 3) treatments, but the effects were not statistically significant; CYP2B6 was induced by phenobarbital (6.5-fold, n = 13) and rifampin (13-fold, n = 14); CYP2C8 was induced by phenobarbital (4.0-fold, n = 4) and rifampin (5.2-fold, n = 4); CYP2C9 was induced by phenobarbital (1.8-fold, n = 14) and rifampin (3.5-fold, n = 10); CYP2C19 was markedly induced by rifampin (37-fold, n = 10), but relatively modestly by phenobarbital (7-fold, n = 9); CYP2D6 was not significantly induced by phenobarbital (n = 5) or rifampin (n = 5); CYP2E1 was induced by phenobarbital (1.7-fold, n = 5), rifampin (2.2-fold, n = 5), and isoniazid (2.3-fold, n = 5); and, CYP3A4 was induced by phenobarbital (3.3-fold, n = 42) and rifampin (10-fold, n = 61), but not by beta-naphthoflavone. Based on these observations, we generalize that beta-naphthoflavone induces CYP1A2 and isoniazid induces CYP2E1, whereas rifampin and, to a lesser extent phenobarbital, tend to significantly and consistently induce enzymes of the CYP2A, CYP2B, CYP2C, CYP2E, and CYP3A subfamilies but not the 2D subfamily.
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Affiliation(s)
- Ajay Madan
- XenoTech, LLC, 16825 West 116th Street, Lenexa, KS 66219, USA
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Edwards RJ, Price RJ, Watts PS, Renwick AB, Tredger JM, Boobis AR, Lake BG. Induction of cytochrome P450 enzymes in cultured precision-cut human liver slices. Drug Metab Dispos 2003; 31:282-8. [PMID: 12584154 DOI: 10.1124/dmd.31.3.282] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Precision-cut human liver slices obtained from 11 donors were cultured for 72 h in a defined medium (serum free Williams' medium E) supplemented with 0.1 microM insulin and 0.1 microM dexamethasone (DEX). Liver slices were treated with 50 microM concentrations of beta -naphthoflavone (BNF), lansoprazole, rifampicin (RIF), DEX and methylclofenapate and 500 microM sodium phenobarbital (NaPB). The relative apoprotein levels of 12 cytochrome P450 (P450) enzymes were determined in liver slice microsomes using a panel of antipeptide antibodies. Treatment with BNF significantly induced mean levels of CYP1A2 apoprotein to 160% of levels in 72-h control (no test compound) human liver slice microsomes. NaPB significantly induced levels of CYP3A4 apoprotein to 255% of control and RIF significantly induced levels of CYP2C19 and CYP3A4 apoproteins to 265 and 330% of control, respectively. In addition, treatment with RIF increased levels of CYP2A6 apoprotein to 205% of control, and treatment with both NaPB and RIF increased levels of CYP2B6 apoprotein to 370 and 615% of control, respectively. However, these increases were not statistically significant, owing to a variable response between liver slice preparations from different subjects, this being apparent for all inducible P450s. In contrast, none of the compounds examined significantly increased levels of CYP2C8, CYP2C9, CYP2D6, CYP2E1, and CYP4A11 apoproteins. Levels of CYP1A1 apoprotein were not detected in any liver slice sample, either before or after treatment with the model inducers. Overall, these results demonstrate the utility of cultured human liver slices for assessing the effects of chemicals on P450 enzymes.
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Affiliation(s)
- Robert J Edwards
- School of Medicine, Hammersmith Hospital, London, United Kingdom
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Ishida S, Jinno H, Tanaka-Kagawa T, Ando M, Ohno Y, Ozawa S, Sawada JI. Characterization of human CYP1A1/1A2 induction by DNA microarray and alpha-naphthoflavone. Biochem Biophys Res Commun 2002; 296:172-7. [PMID: 12147246 DOI: 10.1016/s0006-291x(02)00856-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
DNA microarrays and real time PCR were used to analyze the mechanism of gene induction by CYP1A1 inducers, beta-naphthoflavone, and omeprazole, in the human hepatocellular carcinoma HepG2 cells. Reproducible and significant inductions were observed in a limited number of genes including CYP1A1 and CYP1A2. Genes induced by omeprazole included several protein tyrosine kinase targets. This result confirmed that omeprazole could modulate gene expressions through protein tyrosine kinase-mediated pathway. Induction ratios were considerably different from CYP1A1 and CYP1A2 (>10-fold) to other induced genes (<5-fold). alpha-Naphthoflavone, which is known as an antagonist to 2,3,7,8-tetrachlorodibenzo-p-dioxin, inhibited the inductions of heme oxygenase 1, glutamate-cysteine ligase (modifier unit), and thioredoxin reductase by beta-naphthoflavone but not those of CYP1A1 and CYP1A2. It unexpectedly enhanced the beta-naphthoflavone-mediated CYP1A1 and CYP1A2 induction. These results suggest that the CYP1A1 and CYP1A2 genes, which share their 5(') enhancer regions, are regulated differently from the other genes.
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Affiliation(s)
- Seiichi Ishida
- Project Team for Pharmacogenetics, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, 158-8501, Tokyo, Japan.
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