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Abstract
Heterocyclic aromatic amines (HAAs) are mainly formed in the pyrolysis process during high-temperature cooking of meat. Meat consumption is very typical of the western diet, and the amount of meat consumption in the eastern countries is growing rapidly; HAAs represents widespread exposure. HAAs are classified as possible human carcinogens; numerous epidemiological studies have demonstrated regular consumption of meat with HAAs as risk factor for cancers. Specific HAAs have received major attention. For example, 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine has been extensively studied as a genotoxicant and mutagen, with emergent literature on neurotoxicity. Harmane has been extensively studied for a role in essential tremors and potentially Parkinson's disease (PD). Harmane levels have been demonstrated to be elevated in blood and brain in essential tremor patients. Meat consumption has been implicated in the etiology of neurodegenerative diseases; however, the role of toxicants formed during meat preparation has not been studied. Epidemiological studies are currently examining the association between HAAs and risk of neurodegenerative diseases such as essential tremors and PD. Studies from our laboratory and others have provided strong evidence that HAA exposure produces PD and Alzheimer's disease-relevant neurotoxicity in cellular and animal models. In this review, we summarize and critically evaluate previous studies on HAA-induced neurotoxicity and the molecular basis of potential neurotoxic effects of HAAs. The available studies provide strong support for the premise that HAAs may impact neurological function and that addressing gaps in understanding of adverse neurological outcomes is critical to determine whether these compounds are modifiable risk factors.
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Affiliation(s)
- Tauqeerunnisa Syeda
- School of Health Sciences, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jason R Cannon
- School of Health Sciences, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, Indiana 47907, United States
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Hölzl-Armstrong L, Nævisdal A, Cox JA, Long AS, Chepelev NL, Phillips DH, White PA, Arlt VM. In vitro mutagenicity of selected environmental carcinogens and their metabolites in MutaMouse FE1 lung epithelial cells. Mutagenesis 2020; 35:453-463. [PMID: 33399867 PMCID: PMC7846080 DOI: 10.1093/mutage/geaa032] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 11/21/2020] [Indexed: 11/12/2022] Open
Abstract
Chemicals in commerce or under development must be assessed for genotoxicity; assessment is generally conducted using validated assays (e.g. Tk mouse lymphoma assay) as part of a regulatory process. Currently, the MutaMouse FE1 cell mutagenicity assay is undergoing validation for eventual use as a standard in vitro mammalian mutagenicity assay. FE1 cells have been shown to be metabolically competent with respect to some cytochrome P450 (CYP) isozymes; for instance, they can convert the human carcinogen benzo[a]pyrene into its proximate mutagenic metabolite. However, some contradictory results have been noted for other genotoxic carcinogens that require two-step metabolic activation (e.g. 2-acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoxaline). Here, we examined three known or suspected human carcinogens, namely acrylamide, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 4-aminobiphenyl (4-ABP), together with their proximate metabolites (i.e. glycidamide, N-OH-PhIP and N-OH-4-ABP), to aid in the validation of the FE1 cell mutagenicity assay. Assessments of the parent compounds were conducted both in the presence and absence of an exogenous metabolic activation mixture S9; assessments of the metabolites were in the absence of S9. The most potent compound was N-OH-PhIP -S9, which elicited a mutant frequency (MF) level 5.3-fold over background at 5 µM. There was a 4.3-fold increase for PhIP +S9 at 5 µM, a 1.7-fold increase for glycidamide -S9 at 3.5 mM and a 1.5-fold increase for acrylamide +S9 at 4 mM. Acrylamide -S9 elicited a marginal 1.4-fold MF increase at 8 mM. Treatment with PhIP -S9, 4-ABP ±S9 and N-OH-4-ABP -S9 failed to elicit significant increases in lacZ MF with any of the treatment conditions tested. Gene expression of key CYP isozymes was quantified by RT-qPCR. Cyp1a1, 1a2 and 1b1 are required to metabolise PhIP and 4-ABP. Results showed that treatment with both compounds induced expression of Cyp1a1 and Cyp1b1 but not Cyp1a2. Cyp2e1, which catalyses the bioactivation of acrylamide to glycidamide, was not induced after acrylamide treatment. Overall, our results confirm that the FE1 cell mutagenicity assay has the potential for use alongside other, more traditional in vitro mutagenicity assays.
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Affiliation(s)
- Lisa Hölzl-Armstrong
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, London, UK
| | - Andrea Nævisdal
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, London, UK
| | - Julie A Cox
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Alexandra S Long
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Nikolai L Chepelev
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, London, UK
| | - Paul A White
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, London, UK
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Kim JK, Strapazzon N, Gallaher CM, Stoll DR, Thomas W, Gallaher DD, Trudo SP. Comparison of short- and long-term exposure effects of cruciferous and apiaceous vegetables on carcinogen metabolizing enzymes in Wistar rats. Food Chem Toxicol 2017; 108:194-202. [PMID: 28764905 DOI: 10.1016/j.fct.2017.07.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 05/13/2017] [Accepted: 07/28/2017] [Indexed: 10/19/2022]
Abstract
Cruciferous and apiaceous vegetables may be chemopreventive due to their ability to modulate carcinogen-metabolizing enzymes but whether the effects on such enzymes are sustained over time is unknown. To examine the short- and long-term effects of the vegetables, rats were fed one of four diets for 7, 30, or 60 d: AIN-93G, CRU (21% cruciferous vegetables-fresh broccoli, green cabbage, watercress), API (9% apiaceous vegetables - fresh parsnips, celery), or API + CRU (10.5% CRU + 4.5% API). Although CRU increased activity and protein expression of cytochrome P450 (CYP) 1A1 and CYP1A2 after 7 d, only activity was sustained after 30 and 60 d. There was a trend towards an interaction between the length of feeding period and CRU for CYP1A1 activity; activity increased with greater time of feeding. API increased CYP1A2 activity but decreased sulfotransferase 1A1 activity after 7 d, although not at later times. Altogether, increased CYP1A activity by CRU was maintained with long term feeding while protein amount decreased, suggesting influence by mechanisms other than, or in addition to, transcriptional regulation. Thus, response patterns and interactions with length of feeding may differ, depending upon the types of vegetables and enzymes, requiring caution when interpreting the results of short-term feeding studies.
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Affiliation(s)
- Jae Kyeom Kim
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA
| | - Noemia Strapazzon
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA
| | - Cynthia M Gallaher
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA
| | - Dwight R Stoll
- Department of Chemistry, Gustavus Adolphus College, Saint Peter, MN 56082, USA
| | - William Thomas
- Division of Biostatistics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel D Gallaher
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA
| | - Sabrina P Trudo
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA.
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Khan MKA, Akhtar S, Arif JM. Development of In Silico Protocols to Predict Structural Insights into the Metabolic Activation Pathways of Xenobiotics. Interdiscip Sci 2017; 10:329-345. [PMID: 28527150 DOI: 10.1007/s12539-017-0237-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 05/05/2017] [Accepted: 05/09/2017] [Indexed: 11/26/2022]
Abstract
To establish in silico model to predict the structural insight into the metabolic bioactivation pathway of xenobiotics, we considered two specific and one non-specific mammary procarcinogen [e.g., dibenzo[a,l]pyrene (DBP), 7,12-dimethylbenz[a]anthracene (DMBA), and benzo[a]pyrene (BP)]. The CYP1A1, 1B1, 2C9, 1A2 and 2B6 reported in wet-lab studies to actively metabolize DBP also showed strong binding energies (kcal/mol) of -11.50, -10.67, -10.37, -9.76 and -9.72, respectively, with inhibition constants ranging between 0.01 and 0.08 µM. The CYP3A4 depicted minimum binding energy (-9.51 kcal/mol) which is in agreement with the wet-lab reports. Further, relatively better affinity of CYP1A1 and CYP1B1 with the dibenzo[a,l]pyrene-11,12-diol (DBPD) might be indicative of their involvement in carcinogenicity of parent compound. Like DBP, BP (-10.13 kcal/mol, Ki: 0.04 µM) and BP-diols (BPD) (-9.01 kcal/mol, Ki: 0.25 µM) observed plausible binding with CYP1A1 supporting to the reported data that emphasize the major contribution of CYP1A1 in the activation of similar procarcinogens and mutagens. Likewise, in silico results further highlighted the CYP1A1 as key player in bioactivation of DMBA to its carcinogenic metabolites. In case of PhIP metabolism, strong binding interaction predicted with CYP1A1 (-9.63 kcal/mol) rather than CYP1A2 (-8.84 kcal/mol). Dissimilarity in the binding affinity of PhIP might be due to its basic scaffold. Further, molecular dynamics (MD) simulation of 10 ns has been revealed that docked complexes of CYP1A1 with DBP, DMBA and BP are comparatively more stable than the complex of PhIP. Moreover, the current findings might be valuable as reference model in prediction and elucidation of the approximate metabolic pathway of xenobiotics.
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Affiliation(s)
- M Kalim A Khan
- Department of Bioengineering, Faculty of Engineering, Integral University, Lucknow, 226026, India
| | - Salman Akhtar
- Department of Bioengineering, Faculty of Engineering, Integral University, Lucknow, 226026, India
| | - Jamal M Arif
- Department of Biosciences, Faculty of Applied Sciences, Integral University, Kursi Road, P.O. Box Basha, Lucknow, 226026, India.
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Sheng J, Wang Y, Turesky RJ, Kluetzman K, Zhang QY, Ding X. Novel Transgenic Mouse Model for Studying Human Serum Albumin as a Biomarker of Carcinogenic Exposure. Chem Res Toxicol 2016; 29:797-809. [PMID: 27028147 DOI: 10.1021/acs.chemrestox.5b00529] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Albumin is a commonly used serum protein for studying human exposure to xenobiotic compounds, including therapeutics and environmental pollutants. Often, the reactivity of albumin with xenobiotic compounds is studied ex vivo with human albumin or plasma/serum samples. Some studies have characterized the reactivity of albumin with chemicals in rodent models; however, differences between the orthologous peptide sequences of human and rodent albumins can result in the formation of different types of chemical-protein adducts with different interaction sites or peptide sequences. Our goal is to generate a human albumin transgenic mouse model that can be used to establish human protein biomarkers of exposure to hazardous xenobiotics for human risk assessment via animal studies. We have developed a human albumin transgenic mouse model and characterized the genotype and phenotype of the transgenic mice. The presence of the human albumin gene in the genome of the model mouse was confirmed by genomic PCR analysis, whereas liver-specific expression of the transgenic human albumin mRNA was validated by RT-PCR analysis. Further immunoblot and mass spectrometry analyses indicated that the transgenic human albumin protein is a full-length, mature protein, which is less abundant than the endogenous mouse albumin that coexists in the serum of the transgenic mouse. The transgenic protein was able to form ex vivo adducts with a genotoxic metabolite of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, a procarcinogenic heterocyclic aromatic amine formed in cooked meat. This novel human albumin transgenic mouse model will facilitate the development and validation of albumin-carcinogen adducts as biomarkers of xenobiotic exposure and/or toxicity in humans.
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Affiliation(s)
- Jonathan Sheng
- Wadsworth Center, New York State Department of Health , Albany, New York 12201, United States
| | - Yi Wang
- Masonic Cancer Center and Department of Medicinal Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Robert J Turesky
- Masonic Cancer Center and Department of Medicinal Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Kerri Kluetzman
- Wadsworth Center, New York State Department of Health , Albany, New York 12201, United States
| | - Qing-Yu Zhang
- Wadsworth Center, New York State Department of Health , Albany, New York 12201, United States
| | - Xinxin Ding
- College of Nanoscale Science, SUNY Polytechnic Institute , Albany, New York 12203, United States
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Selective Inhibition of Bakuchicin Isolated from Psoralea corylifolia on CYP1A in Human Liver Microsomes. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 2016:5198743. [PMID: 26977174 PMCID: PMC4763008 DOI: 10.1155/2016/5198743] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/12/2016] [Indexed: 11/30/2022]
Abstract
Bakuchicin is a furanocoumarin isolated from Psoralea corylifolia and shows several biological activities. Although there have been studies on the biological effects of bakuchicin, its modulation potency of CYP activities has not been previously investigated. Here, we investigated the inhibitory effects of bakuchicin on the activities of CYP isoforms by using a cocktail of probe substrates in pooled human liver microsomes (HLMs) and human recombinant cDNA-expressed CYP. Bakuchicin strongly inhibited CYP1A-mediated phenacetin O-deethylation with an IC50 value of 0.43 μM in HLMs. It was confirmed by human recombinant cDNA-expressed CYP1A1 and CYP1A2 with a Ki value of 0.11 μM and 0.32 μM, respectively. A Lineweaver-Burk plot indicated that the inhibition mechanism of bakuchicin was competitive inhibition. Overall, this is the first study to investigate the potential CYP1A1 and CYP1A2 inhibition associated with bakuchicin and to report its competitive inhibitory effects on HLMs.
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Kim BR, Seo JY, Sung MK, Park JHY, Suh HJ, Liu KH, Kim JS. Suppression of 7,12-dimethylbenz(a)anthracene-induced mammary tumorigenesis by glyceollins. Mol Nutr Food Res 2015; 59:907-17. [DOI: 10.1002/mnfr.201400726] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 01/23/2015] [Accepted: 01/26/2015] [Indexed: 01/03/2023]
Affiliation(s)
- Bo Ram Kim
- School of Food Science and Biotechnology; Kyungpook National University; Daegu Republic of Korea
| | - Ji-Yeon Seo
- School of Food Science and Biotechnology; Kyungpook National University; Daegu Republic of Korea
| | - Mi-Kyung Sung
- Department of Food and Nutrition; Sookmyung Women's University, Seoul; Republic of Korea
| | - Jung Han Yoon Park
- Department of Food Science and Nutrition; Hallym University; Chuncheon Republic of Korea
| | - Hwa-Jin Suh
- Gyeongbuk Natural Color Industry Institute; Gyeongbuk Republic of Korea
| | - Kwang Hyeon Liu
- College of Pharmacy; Kyungpook National University; Daegu Republic of Korea
| | - Jong-Sang Kim
- School of Food Science and Biotechnology; Kyungpook National University; Daegu Republic of Korea
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Vlaming MLH, Teunissen SF, van de Steeg E, van Esch A, Wagenaar E, Brunsveld L, de Greef TFA, Rosing H, Schellens JHM, Beijnen JH, Schinkel AH. Bcrp1;Mdr1a/b;Mrp2 combination knockout mice: altered disposition of the dietary carcinogen PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) and its genotoxic metabolites. Mol Pharmacol 2014; 85:520-30. [PMID: 24334255 DOI: 10.1124/mol.113.088823] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
The multidrug transporters breast cancer resistance protein (BCRP), multidrug-resistance protein 1 (MDR1), and multidrug-resistance-associated protein (MRP) 2 and 3 eliminate toxic compounds from tissues and the body and affect the pharmacokinetics of many drugs and other potentially toxic compounds. The food-derived carcinogen PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) is transported by BCRP, MDR1, and MRP2. To investigate the overlapping functions of Bcrp1, Mdr1a/b, and Mrp2 in vivo, we generated Bcrp1;Mdr1a/b;Mrp2(-/-) mice, which are viable and fertile. These mice, together with Bcrp1;Mrp2;Mrp3(-/-) mice, were used to study the effects of the multidrug transporters on the pharmacokinetics of PhIP and its metabolites. Thirty minutes after oral or intravenous administration of PhIP (1 mg/kg), the PhIP levels in the small intestine were reduced 4- to 6-fold in Bcrp1;Mdr1a/b;Mrp2(-/) (-) and Bcrp1;Mrp2;Mrp3(-/-) mice compared with wild-type mice. Fecal excretion of PhIP was reduced 8- to 20-fold in knockouts. Biliary PhIP excretion was reduced 41-fold in Bcrp1;Mdr1a/b;Mrp2(-/-) mice. Biliary and small intestine levels of PhIP metabolites were reduced in Bcrp1;Mrp2-deficient mice. Furthermore, in both knockout strains, kidney levels and urinary excretion of genotoxic PhIP-metabolites were significantly increased, suggesting that reduced biliary excretion of PhIP and PhIP metabolites leads to increased urinary excretion of these metabolites and increased systemic exposure. Bcrp1 and Mdr1a limited PhIP brain accumulation. In Bcrp1;Mrp2;Mrp3(-/-), but not Bcrp1;Mdr1a/b;Mrp(-/-) mice, the carcinogenic metabolites N2-OH-PhIP (2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine) and PhIP-5-sulfate (a genotoxicity marker) accumulated in liver tissue, indicating that Mrp3 is involved in the sinusoidal secretion of these compounds. We conclude that Bcrp1, Mdr1a/b, Mrp2, and Mrp3 significantly affect tissue disposition and biliary and fecal elimination of PhIP and its carcinogenic metabolites and may affect PhIP-induced carcinogenesis as a result.
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Affiliation(s)
- Maria L H Vlaming
- Divisions of Molecular Oncology (M.L.H.V., E.v.d.S., A.v.E., E.W., A.H.S.) and Clinical Pharmacology (J.H.M.S.), The Netherlands Cancer Institute, Amsterdam, The Netherlands; Division of Pharmacy & Pharmacology, Slotervaart Hospital, Amsterdam, The Netherlands (S.F.T., H.R., J.H.B.); Laboratory of Chemical Biology, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands (L.B., T.F.A.d.G.); and Department of Pharmaceutical Sciences, Science Faculty, Utrecht University, Utrecht, The Netherlands (J.H.M.S., J.H.B.)
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Badal S, Delgoda R. Role of the modulation of CYP1A1 expression and activity in chemoprevention. J Appl Toxicol 2014; 34:743-53. [PMID: 24532440 DOI: 10.1002/jat.2968] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/06/2013] [Accepted: 11/06/2013] [Indexed: 12/11/2022]
Affiliation(s)
- S. Badal
- Natural Products Institute, Faculty of Science and Technology; University of the West Indies; Mona Kingston 7 Jamaica, West Indies
| | - R. Delgoda
- Natural Products Institute, Faculty of Science and Technology; University of the West Indies; Mona Kingston 7 Jamaica, West Indies
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Dong H, Shertzer HG, Genter MB, Gonzalez FJ, Vasiliou V, Jefcoate C, Nebert DW. Mitochondrial targeting of mouse NQO1 and CYP1B1 proteins. Biochem Biophys Res Commun 2013; 435:727-32. [PMID: 23692925 DOI: 10.1016/j.bbrc.2013.05.051] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 05/12/2013] [Indexed: 10/26/2022]
Abstract
Four dioxin-inducible enzymes--NAD(P)H: quinone oxidoreductase-1 (NQO1) and three cytochromes P450 (CYP1A1, CYP1A2 & CYP1B1)--are implicated in both detoxication and metabolic activation of various endobiotics and xenobiotics. NQO1 is generally regarded as a cytosolic enzyme; whereas CYP1 proteins are located primarily in endoplasmic reticulum (ER), CYP1A1 and CYP1A2 proteins are also targeted to mitochondria. This lab has generated Cyp1a1(mc/mc) and Cyp1a1(mtt/mtt) knock-in mouse lines in which CYP1A1 protein is targeted exclusively to ER (microsomes) and mitochondria, respectively. Comparing dioxin-treated Cyp1(+/+) wild-type, Cyp1a1(mc/mc), Cyp1a1(mtt/mtt), and Cyp1a1(-/-), Cyp1b1(-/-) and Nqo1(-/-) knockout mice, in the present study we show that [a] NQO1 protein locates to cytosol, ER and mitochondria, [b] CYP1B1 protein (similar to CYP1A1 and CYP1A2 proteins) traffics to mitochondria as well as ER, and [c] NQO1 and CYP1B1 targeting to mitochondrial or ER membranes is independent of CYP1A1 presence in that membrane.
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Affiliation(s)
- Hongbin Dong
- Department of Environmental Health and Center for Environmental Genetics, University Cincinnati Medical Center, Cincinnati, OH 45267-0056, USA
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Dobbernack G, Meinl W, Schade N, Florian S, Wend K, Voigt I, Himmelbauer H, Gross M, Liehr T, Glatt H. Altered tissue distribution of 2-amino-1-methyl-6-phenylimidazo[4,5- b ]pyridine-DNA adducts in mice transgenic for human sulfotransferases 1A1 and 1A2. Carcinogenesis 2011; 32:1734-40. [DOI: 10.1093/carcin/bgr204] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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12
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Teunissen S, Vlaming M, Rosing H, Schellens J, Schinkel A, Beijnen J. Development and validation of a liquid chromatography–tandem mass spectrometry assay for the analysis of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and its metabolite 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-OH-PhIP) in plasma, urine, bile, intestinal contents, faeces and eight selected tissues from mice. J Chromatogr B Analyt Technol Biomed Life Sci 2010; 878:2353-62. [DOI: 10.1016/j.jchromb.2010.07.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 07/05/2010] [Accepted: 07/20/2010] [Indexed: 12/29/2022]
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13
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Bendaly J, Metry KJ, Doll MA, Jiang G, States JC, Smith NB, Neale JR, Holloman JL, Pierce WM, Hein DW. Role of human CYP1A1 and NAT2 in 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine-induced mutagenicity and DNA adducts. Xenobiotica 2010; 39:399-406. [PMID: 19301197 DOI: 10.1080/00498250902748953] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is carcinogenic in multiple organs and numerous species. Bioactivation of PhIP is initiated by PhIP N(2)-hydroxylation catalysed by cytochrome P450s. Following N-hydroxylation, O-acetylation catalysed by N-acetyltransferase 2 (NAT2) is considered a further possible activation pathway. Genetic polymorphisms in NAT2 may modify cancer risk following exposure. Nucleotide excision repair-deficient Chinese hamster ovary (CHO) cells stably transfected with human cytochrome P4501A1 (CYP1A1) and a single copy of either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles were used to test the effect of CYP1A1 and NAT2 polymorphism on PhIP genotoxicity. Cells transfected with NAT2*4 had significantly higher levels of N-hydroxy-PhIP O-acetyltransferase (p = 0.0150) activity than cells transfected with NAT2*5B. Following PhIP treatment, CHO cell lines transfected with CYP1A1, CYP1A1/NAT2*4 and CYP1A1/NAT2*5B each showed concentration-dependent cytotoxicity and hypoxanthine phosphoribosyl transferase (hprt) mutagenesis not observed in untransfected CHO cells. dG-C8-PhIP was the primary DNA adduct formed and levels were dose dependent in transfected CHO cells in the order: CYP1A1 < CYP1A1 and NAT2*5B < CYP1A1 and NAT2*4, although levels did not differ significantly (p > 0.05) following one-way analysis of variance. These results strongly support activation of PhIP by CYP1A1 with little effect of human NAT2 genetic polymorphism on mutagenesis and DNA damage.
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Affiliation(s)
- J Bendaly
- Department of Pharmacology and Toxicology, James Graham Brown Cancer Center, and Center for Environmental Genomics and Integrative Biology, University of Louisville School of Medicine, Louisville, KY, USA
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Miura P, Coriati A, Bélanger G, De Repentigny Y, Lee J, Kothary R, Holcik M, Jasmin BJ. The utrophin A 5'-UTR drives cap-independent translation exclusively in skeletal muscles of transgenic mice and interacts with eEF1A2. Hum Mol Genet 2010; 19:1211-20. [PMID: 20053670 DOI: 10.1093/hmg/ddp591] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The molecular mechanisms regulating expression of utrophin A are of therapeutic interest since upregulating its expression at the sarcolemma can compensate for the lack of dystrophin in animal models of Duchenne Muscular Dystrophy (DMD). The 5'-UTR of utrophin A has been previously shown to drive cap-independent internal ribosome entry site (IRES)-mediated translation in response to muscle regeneration and glucocorticoid treatment. To determine whether the utrophin A IRES displays tissue specific activity, we generated transgenic mice harboring control (CMV/betaGAL/CAT) or utrophin A 5'-UTR (CMV/betaGAL/UtrA/CAT) bicistronic reporter transgenes. Examination of multiple tissues from two CMV/betaGAL/UtrA/CAT lines revealed that the utrophin A 5'-UTR drives cap-independent translation of the reporter gene exclusively in skeletal muscles and no other examined tissues. This expression pattern suggested that skeletal muscle-specific factors are involved in IRES-mediated translation of utrophin A. We performed RNA-affinity chromatography experiments combined with mass spectrometry to identify trans-factors that bind the utrophin A 5'-UTR and identified eukaryotic elongation factor 1A2 (eEF1A2). UV-crosslinking experiments confirmed the specificity of this interaction. Regions of the utrophin A 5'-UTR that bound eEF1A2 also mediated cap-independent translation in C2C12 muscle cells. Cultured cells lacking eEF1A2 had reduced IRES activity compared with cells overexpressing eEF1A2. Together, these results suggest an important role for eEF1A2 in driving cap-independent translation of utrophin A in skeletal muscle. The trans-factors and signaling pathways driving skeletal-muscle specific IRES-mediated translation of utrophin A could provide unique targets for developing pharmacological-based DMD therapies.
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Affiliation(s)
- P Miura
- Department of Cellular & Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
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15
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Androutsopoulos VP, Tsatsakis AM, Spandidos DA. Cytochrome P450 CYP1A1: wider roles in cancer progression and prevention. BMC Cancer 2009; 9:187. [PMID: 19531241 PMCID: PMC2703651 DOI: 10.1186/1471-2407-9-187] [Citation(s) in RCA: 291] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 06/16/2009] [Indexed: 02/08/2023] Open
Abstract
CYP1A1 is one of the main cytochrome P450 enzymes, examined extensively for its capacity to activate compounds with carcinogenic properties. Continuous exposure to inhalation chemicals and environmental carcinogens is thought to increase the level of CYP1A1 expression in extrahepatic tissues, through the aryl hydrocarbon receptor (AhR). Although the latter has long been recognized as a ligand-induced transcription factor, which is responsible for the xenobiotic activating pathway of several phase I and phase II metabolizing enzymes, recent evidence suggests that the AhR is involved in various cell signaling pathways critical to cell cycle regulation and normal homeostasis. Disregulation of these pathways is implicated in tumor progression. In addition, it is becoming increasingly evident that CYP1A1 plays an important role in the detoxication of environmental carcinogens, as well as in the metabolic activation of dietary compounds with cancer preventative activity. Ultimately the contribution of CYP1A1 to cancer progression or prevention may depend on the balance of procarcinogen activation/detoxication and dietary natural product extrahepatic metabolism.
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Affiliation(s)
- Vasilis P Androutsopoulos
- Department of Medicine, Division of Forensic Sciences and Toxicology, University of Crete, Crete, Greece.
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16
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Lam TK, Cross AJ, Consonni D, Randi G, Bagnardi V, Bertazzi PA, Caporaso NE, Sinha R, Subar AF, Landi MT. Intakes of red meat, processed meat, and meat mutagens increase lung cancer risk. Cancer Res 2009; 69:932-9. [PMID: 19141639 DOI: 10.1158/0008-5472.can-08-3162] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Red and processed meat intake may increase lung cancer risk. However, the epidemiologic evidence is inconsistent and few studies have evaluated the role of meat mutagens formed during high cooking temperatures. We investigated the association of red meat, processed meat, and meat mutagen intake with lung cancer risk in Environment And Genetics in Lung cancer Etiology, a population-based case-control study. Primary lung cancer cases (n = 2,101) were recruited from 13 hospitals within the Lombardy region of Italy examining approximately 80% of the cases from the area. Noncancer population controls (n = 2,120), matched to cases on gender, residence, and age, were randomly selected from the same catchment area. Diet was assessed in 1,903 cases and 2,073 controls and used in conjunction with a meat mutagen database to estimate intake of heterocyclic amines (HCA) and benzo(a)pyrene (BaP). Multivariable odds ratios (OR) and 95% confidence intervals (95% CI) for sex-specific tertiles of intake were calculated using unconditional logistic regression. Red and processed meat were positively associated with lung cancer risk (highest-versus-lowest tertile: OR, 1.8; 95% CI, 1.5-2.2; P trend < 0.001 and OR, 1.7; 95% CI, 1.4-2.1; P trend < 0.001, respectively); the risks were strongest among never smokers (OR, 2.4; 95% CI, 1.4-4.0; P trend = 0.001 and OR, 2.5; 95% CI, 1.5-4.2; P trend = 0.001, respectively). HCAs and BaP were significantly associated with increased risk of lung cancer. When separated by histology, significant positive associations for both meat groups were restricted to adenocarcinoma and squamous cell carcinoma but not small cell carcinoma of the lung. In summary, red meat, processed meat, and meat mutagens were independently associated with increased risk of lung cancer.
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Affiliation(s)
- Tram Kim Lam
- Cancer Prevention Fellowship Program, Office of Preventive Oncology, National Cancer Institute, NIH, Department of Health and Human Services, [corrected] Bethesda, Maryland 20892-7236, USA
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17
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Dong H, Dalton TP, Miller ML, Chen Y, Uno S, Shi Z, Shertzer HG, Bansal S, Avadhani NG, Nebert DW. Knock-in mouse lines expressing either mitochondrial or microsomal CYP1A1: differing responses to dietary benzo[a]pyrene as proof of principle. Mol Pharmacol 2008; 75:555-67. [PMID: 19047483 DOI: 10.1124/mol.108.051888] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In the past, CYP1A1 protein was known to be located in the endoplasmic reticulum (ER; microsomes). More recently, CYP1A1 was shown also to be targeted to the inner mitochondrial membrane; mitochondrial import is dependent on NH(2)-terminal processing that exposes a cryptic targeting signal. It is interesting that microsomal and mitochondrial CYP1A1 enzymes exhibit different substrate specificities, electron donors, and inducer properties. To understand the physiological functions of microsomal versus mitochondrial CYP1A1, we have generated three knock-in lines by altering the CYP1A1 NH(2) terminus. Cyp1a1(mtt/mtt) mice encode an NH(2)-terminal 31-amino acid-truncated protein, deleting the ER-targeting signal and exposing the cryptic mitochondrial-targeting signal. Cyp1a1(mtp/mtp) mice encode a protein carrying L7N and L17N mutations; this mutant lacks the signal recognition particle (SRP)-binding site and subsequent ER-targeting, but requires proteolysis by a cytosolic peptidase for mitochondrial import. Cyp1a1(mc/mc) mice encode a microsomal protein having R34D and K39I mutations, which abolish the mitochondrial targeting signal. After dioxin or beta-naphthoflavone treatment of these mouse lines, the CYP1A1 protein was shown to be located in the mitochondria of the Cyp1a1(mtp/mtp) and Cyp1a1(mtt/mtt) lines and in microsomes of the Cyp1a1(mc/mc) line. To test for differences in function, we compared the response to dietary benzo[a]pyrene (BaP). After 18 days of daily oral BaP, wild-type and Cyp1a1(mc/mc) mice were completely protected, whereas Cyp1a1(-/-) and Cyp1a1(mtp/mtp) mice showed striking toxicity and compensatory up-regulation of CYP1A2 and CYP1B1 mRNA in several tissues. Our data support the likelihood that it is the microsomal rather than mitochondrial CYP1A1 enzyme that protects against oral BaP toxicity.
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Affiliation(s)
- Hongbin Dong
- Department of Environmental Health,Center for Environmental Genetics, University of Cincinnati Medical Center, Cincinnati OH 45267-0056
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18
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Shi Z, Chen Y, Dong H, Amos-Kroohs RM, Nebert DW. Generation of a 'humanized' hCYP1A1_1A2_Cyp1a1/1a2(-/-)_Ahrd mouse line harboring the poor-affinity aryl hydrocarbon receptor. Biochem Biophys Res Commun 2008; 376:775-80. [PMID: 18814841 DOI: 10.1016/j.bbrc.2008.09.068] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 09/16/2008] [Indexed: 11/16/2022]
Abstract
Herein, we describe generation of the hCYP1A1_1A2_Cyp1a1/1a2(-/-)_Ahr(d) mouse line, which carries human functional CYP1A1 and CYP1A2 genes in the absence of mouse Cyp1a1 and Cyp1a2 genes, in a (>99.8%) background of the C57BL/6J genome and harboring the poor-affinity aryl hydrocarbon receptor (AHR) from the DBA/2J mouse. We have characterized this line by comparing it to our previously created hCYP1A1_1A2_Cyp1a1/1a2(-/-)_Ahr(b1) line-which carries the same but has the high-affinity AHR of the C57BL/6J mouse. By quantifying CYP1A1 and CYP1A2 mRNA in liver, lung and kidney of dioxin-treated mice, we show that dose-response curves in hCYP1A1_1A2_Cyp1a1/1a2(-/-)_Ahr(d) mice are shifted to the right of those in hCYP1A1_1A2_Cyp1a1/1a2(-/-)_Ahr(b1) mice-similar to, but not as robust as, dose-response curves in DBA/2J versus C57BL/6J mice. This new mouse line is perhaps more relevant than the former to human risk assessment vis-à-vis human CYP1A1 and CYP1A2 substrates, because poor-affinity rather than high-affinity AHR occurs in the vast majority of the human population.
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Affiliation(s)
- Zhanquan Shi
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, PO Box 670056, Cincinnati, OH 45267-0056, USA
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19
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Bellocq D, Molina J, Rathahao E, Canlet C, Taché S, Martin PG, Pierre F, Paris A. High potency of bioactivation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in mouse colon epithelial cells with ApcMin mutation. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2008; 653:34-43. [DOI: 10.1016/j.mrgentox.2008.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 01/21/2008] [Accepted: 02/14/2008] [Indexed: 12/27/2022]
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Ito S, Chen C, Satoh J, Yim S, Gonzalez FJ. Dietary phytochemicals regulate whole-body CYP1A1 expression through an arylhydrocarbon receptor nuclear translocator-dependent system in gut. J Clin Invest 2007; 117:1940-50. [PMID: 17607366 PMCID: PMC1890999 DOI: 10.1172/jci31647] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 04/24/2007] [Indexed: 12/20/2022] Open
Abstract
Cytochrome P450 1A1 (CYP1A1) is one of the most important detoxification enzymes due to its broad substrate specificity and wide distribution throughout the body. On the other hand, CYP1A1 can also produce highly carcinogenic intermediate metabolites through oxidation of polycyclic aromatic hydrocarbons. We describe what we believe to be a novel regulatory system for whole-body CYP1A1 expression by a factor originating in the gut. A mutant mouse was generated in which the arylhydrocarbon receptor nuclear translocator (Arnt) gene is disrupted predominantly in the gut epithelium. Surprisingly, CYP1A1 mRNA expression and enzymatic activities were markedly elevated in almost all non-gut tissues in this mouse line. The induction was even observed in early-stage embryos in pregnant mutant females. Interestingly, the upregulation was CYP1A1 selective and lost upon administration of a synthetic purified diet. Moreover, the increase was recovered by addition of the natural phytochemical indole-3-carbinol to the purified diet. These results suggest that an Arnt-dependent pathway in gut has an important role in regulation of the metabolism of dietary CYP1A1 inducers and whole-body CYP1A1 expression. This machinery might be involved in naturally occurring carcinogenic processes and/or other numerous biological responses mediated by CYP1A1 activity.
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Affiliation(s)
- Shinji Ito
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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21
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Chen C, Ma X, Malfatti MA, Krausz KW, Kimura S, Felton JS, Idle JR, Gonzalez FJ. A comprehensive investigation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) metabolism in the mouse using a multivariate data analysis approach. Chem Res Toxicol 2007; 20:531-42. [PMID: 17279779 PMCID: PMC1850849 DOI: 10.1021/tx600320w] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a potent rodent carcinogen and a potential human carcinogen because of its existence in the normal human diet. N2-OH-PhIP, a major PhIP metabolite, has been identified as a precursor of genotoxic species. In vitro data supported the view that CYP1A2 is the major enzyme responsible for the formation of N2-OH-PhIP. However, disruption of the CYP1A2 gene in mouse failed to inhibit PhIP-induced carcinogenesis. To investigate the mechanism underlying this observation, the metabolism of PhIP in wild-type, Cyp1a2-null, and CYP1A2-humanized mice was examined in detail using a metabolomic approach. Following data acquisition in a high-resolution LC-MS system, urinary metabolomes of the control and PhIP-treated mice were characterized in a principal component analysis (PCA) model. Comprehensive metabolite profiles of PhIP in high dose (10 mg/kg) and low dose (100 microg/kg) were established through analyzing urinary ions contributing to the separation of three mouse lines in the multivariate model and by measuring radiolabled PhIP metabolite in a radio-HPLC assay, respectively. The genotoxicity of PhIP to three mouse lines was evaluated by measuring DNA adduction levels in liver, lung, colon, and mammary gland. On the basis of the chemical identities of 17 urinary PhIP metabolites, including eight novel metabolites, multivariate data analysis revealed the role of CYP1A2 in PhIP metabolism and a human-mouse interspecies difference in the catalytic activity of CYP1A2. In addition, the results also showed that Cyp1a2-null mice still possess significant N2-hydroxylation and DNA adduction activities, which may be partially attributed to mouse CYP2C enzymes according to the results from in vitro microsome and Supersome incubations and antibody inhibition experiments.
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Affiliation(s)
- Chi Chen
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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22
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Nebert DW, Dalton TP. The role of cytochrome P450 enzymes in endogenous signalling pathways and environmental carcinogenesis. Nat Rev Cancer 2006; 6:947-60. [PMID: 17128211 DOI: 10.1038/nrc2015] [Citation(s) in RCA: 656] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Some cytochrome P450 (CYP) heme-thiolate enzymes participate in the detoxication and, paradoxically, the formation of reactive intermediates of thousands of chemicals that can damage DNA, as well as lipids and proteins. CYP expression can also affect the production of molecules derived from arachidonic acid, and alters various downstream signal-transduction pathways. Such changes can be precursors to malignancy. Recent studies in mice have changed our perceptions about the function of CYP1 enzymes. We suggest a two-tiered system to predict an overall inter-individual risk of tumorigenesis based on DNA variants in certain 'early defence' CYP genes, combined with polymorphisms in various downstream target genes.
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Affiliation(s)
- Daniel W Nebert
- Department of Environmental Health, and Center for Environmental Genetics, University of Cincinnati Medical Center, P.O. Box 670056, Cincinnati, Ohio 45267-0056, USA.
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