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Huang Y, Wang J, Huang S, Zhang X, Hu J. 5-Lipoxygenase Contributes to Benzo[a]pyrene-Induced Cytotoxicity and DNA Damage in Human Bronchial Epithelial Cells. Int J Toxicol 2023; 42:172-181. [PMID: 36537154 DOI: 10.1177/10915818221146286] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Metabolic activation of indirect-acting carcinogens in target organs is a recognized mechanism of carcinogenesis. This study aimed to determine the role of benzo[a]pyrene (BaP) metabolism enzymes lipoxygenase (LOX), cytochrome P4501A1 (CYP1A1), and prostaglandin synthetase (PGS) in the cytotoxicity and DNA damage induced by BaP in the human tracheobronchial epithelial cells (HBECs) using RNA interference strategy and metabolic enzyme inhibitors. Our results showed that in three epithelial cell lines (HBE, HTR-8/SVneo, and HaCat), BaP significantly upregulated 5-LOX protein expression. 15-LOX-2 expression also increased with increasing BaP concentration, but the change was less pronounced than that of 5-LOX. BaP caused significant cytotoxicity, DNA strand breaks, and 8-hydroxy-2'-deoxyguanosine formation in HBE, which was inhibited by 5-LOXshRNA, a specific inhibitor of 5-LOX (AA861), the CYP1A1 inhibitor α-naphthoflavone, and the PGS inhibitor naproxen. The protective effects of 5-LOXshRNA were stronger than AA861, naproxen and α-naphthoflavone. We conclude that BaP may be activated more by 5-LOX than by CYP1A1 and PGS to produce cytotoxicity and DNA damage in HBE.
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Affiliation(s)
- Yun Huang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, 12570Central South University, Changsha, China
| | - Jing Wang
- Shanxi Provincial Center for Disease Control and Prevention, Taiyuan, China
| | - Shaoling Huang
- 633786Changsha Center for Disease Control and Prevention, Changsha, China
| | - Xinge Zhang
- 595060Hunan Provincial Center for Disease Control and Prevention, Changsha, China
| | - Jianan Hu
- Department of Occupational and Environmental Health, Xiangya School of Public Health, 12570Central South University, Changsha, China
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2
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Bukowska B, Mokra K, Michałowicz J. Benzo[a]pyrene—Environmental Occurrence, Human Exposure, and Mechanisms of Toxicity. Int J Mol Sci 2022; 23:ijms23116348. [PMID: 35683027 PMCID: PMC9181839 DOI: 10.3390/ijms23116348] [Citation(s) in RCA: 81] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/02/2022] [Accepted: 06/04/2022] [Indexed: 12/15/2022] Open
Abstract
Benzo[a]pyrene (B[a]P) is the main representative of polycyclic aromatic hydrocarbons (PAHs), and has been repeatedly found in the air, surface water, soil, and sediments. It is present in cigarette smoke as well as in food products, especially when smoked and grilled. Human exposure to B[a]P is therefore common. Research shows growing evidence concerning toxic effects induced by this substance. This xenobiotic is metabolized by cytochrome P450 (CYP P450) to carcinogenic metabolite: 7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), which creates DNA adducts, causing mutations and malignant transformations. Moreover, B[a]P is epigenotoxic, neurotoxic, and teratogenic, and exhibits pro-oxidative potential and causes impairment of animals’ fertility. CYP P450 is strongly involved in B[a]P metabolism, and it is simultaneously expressed as a result of the association of B[a]P with aromatic hydrocarbon receptor (AhR), playing an essential role in the cancerogenic potential of various xenobiotics. In turn, polymorphism of CYP P450 genes determines the sensitivity of the organism to B[a]P. It was also observed that B[a]P facilitates the multiplication of viruses, which may be an additional problem with the widespread COVID-19 pandemic. Based on publications mainly from 2017 to 2022, this paper presents the occurrence of B[a]P in various environmental compartments and human surroundings, shows the exposure of humans to this substance, and describes the mechanisms of its toxicity.
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3
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Oral benzo[a]pyrene administration attenuates dextran sulfate sodium-induced colitis in mice. Chem Biol Interact 2022; 353:109802. [PMID: 34998820 DOI: 10.1016/j.cbi.2022.109802] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 12/28/2021] [Accepted: 01/04/2022] [Indexed: 11/23/2022]
Abstract
Benzo[a]pyrene (BaP) is an environmental pollutant produced by combustion processes and is present in grilled foods as well as in tobacco smoke. BaP acts as an agonist for the aryl hydrocarbon receptor (AHR), and is metabolized by AHR-inducing enzymes. BaP metabolism can result in either detoxification or metabolic activation, the latter leads to an increased risk of disease, particularly lung cancer and cardiovascular disease, in a context-dependent manner. Although AHR activation has been thought to protect against inflammatory bowel disease, it remains unknown whether BaP exerts a protective or deleterious effect on colitis. In this study, we examined the effect of oral BaP administration on colitis induced by dextran sulfate sodium (DSS) in mice, an animal model of inflammatory bowel disease. BaP administration attenuated weight loss, shortening of the colon, disease activity index scores, and histological damage in DSS-induced colitis mice. BaP also suppressed colonic expression of inflammation-associated genes and plasma interleukin-6 secretion induced by DSS treatment. BaP-DNA adduct formation, a marker of BaP metabolic activation, was not enhanced in the colon after DSS treatment. Thus, oral BaP exerts an anti-inflammatory effect on DSS-induced colitis, without the toxicity associated with metabolic activation. The results provide insights into the disease-specific roles of BaP.
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Daytime Restricted Feeding Modifies the Temporal Expression of CYP1A1 and Attenuated Damage Induced by Benzo[a]pyrene in Rat Liver When Administered before CYP1A1 Acrophase. TOXICS 2021; 9:toxics9060130. [PMID: 34199736 PMCID: PMC8228946 DOI: 10.3390/toxics9060130] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/26/2021] [Accepted: 06/02/2021] [Indexed: 11/16/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that heterodimerizes with the AhR nuclear translocator (ARNT) to modulate CYP1A1 expression, a gene involved in the biotransformation of benzo[a]pyrene (BaP). The AhR pathway shows daily variations under the control of the circadian timing system. Daytime restricted feeding (DRF) entrains the expression of genes involved in the processing of nutrients and xenobiotics to food availability. Therefore, we evaluate if temporal AhR, ARNT, and CYP1A1 hepatic expression in rats are due to light/dark cycles or fasting/feeding cycles promoted by DRF. Our results show that AhR oscillates throughout the 24 h period in DRF and ad libitum feeding rats (ALF), showing maximum expression at the same time points. DRF modified the peak of ARNT expression at ZT5; meanwhile, ALF animals showed a peak of maximum expression at ZT17. An increased expression of CYP1A1 was linked to the meal time in both groups of animals. Although a high CYP1A1 expression has been previously associated with BaP genotoxicity, our results show that, compared with the ALF group, DRF attenuated the BaP-CYP1A1 induction potency, the liver DNA-BaP adducts, the liver concentration of unmetabolized BaP, and the blood aspartate aminotransferase and alanine aminotransferase activities when BaP is administered prior to the acrophase of CYP1A1 expression. These results demonstrate that DRF modifies the ARNT and CYP1A1 expression and protects from BaP toxicity.
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5
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Abbass M, Chen Y, Arlt VM, Stürzenbaum SR. Benzo[a]pyrene and Caenorhabditis elegans: defining the genotoxic potential in an organism lacking the classical CYP1A1 pathway. Arch Toxicol 2021; 95:1055-1069. [PMID: 33420596 PMCID: PMC7904753 DOI: 10.1007/s00204-020-02968-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 12/22/2020] [Indexed: 11/29/2022]
Abstract
Benzo[a]pyrene (BaP) is bioactivated in most organisms by the cytochrome P450 (CYP) enzymes, mainly CYP1A1, ultimately resulting in the reactive metabolite BaP-7,8-dihydrodiol-9,10-epoxide (BPDE) capable of covalently binding to DNA and forming adducts. This step has been defined as the key process in cancer initiation in humans. However, limited knowledge is available about the consequences of BaP exposure in organisms lacking this classical CYP1A1 pathway, one example is the model nematode Caenorhabditis elegans. The aim of this study was to define the genotoxic potential of BaP in C. elegans and to advance our understanding of xenobiotic processing in the absence of the CYP1A1 pathway. Exposure to high concentrations of BaP (0-40 µM) significantly affected life cycle endpoints of C. elegans, which were manifested by a reduced reproductive output and shortened life span. An optimised comet assay revealed that DNA damage increased in a dose-dependent manner; however, no bulky DNA adducts (dG-N2-BPDE) were observed by 32P-postlabelling. Global transcriptomic analysis by RNA-Seq identified responsive transcript families, most prominently members of the cyp-35 and UDP-glucuronosyltransferases (UGTs) enzyme families, both of which are linked to xenobiotic metabolism. Strains harbouring mutations in the cyp-35A2 and cyp-35A3 genes were notably less prone to BaP-mediated toxicity, and BaP led to longevity in cyp-35A5 mutants. In summary, BaP induces transcriptional, genotoxic and phenotypic responses in C. elegans, despite the absence of the classical CYP1A1 bioactivation pathway. This provides first evidence that parallel pathways are implicated in BaP metabolism in C. elegans and this seems to be mediated via the cyp-35 pathway.
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Affiliation(s)
- Mustafa Abbass
- Department of Analytical, Environmental and Forensic Sciences, School of Population Health and Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Yuzhi Chen
- Department of Analytical, Environmental and Forensic Sciences, School of Population Health and Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, School of Population Health and Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK.,Toxicology Department, GAB Consulting GmbH, 69126, Heidelberg, Germany
| | - Stephen R Stürzenbaum
- Department of Analytical, Environmental and Forensic Sciences, School of Population Health and Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK.
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Shao Y, Schiwy A, Glauch L, Henneberger L, König M, Mühlenbrink M, Xiao H, Thalmann B, Schlichting R, Hollert H, Escher BI. Optimization of a pre-metabolization procedure using rat liver S9 and cell-extracted S9 in the Ames fluctuation test. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 749:141468. [PMID: 32827816 DOI: 10.1016/j.scitotenv.2020.141468] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 08/01/2020] [Accepted: 08/02/2020] [Indexed: 06/11/2023]
Abstract
Many environmental pollutants pose a toxicological hazard only after metabolic activation. In vitro bioassays using cell lines or bacteria have often no or reduced metabolic activity, which impedes their use in the risk assessment. To improve the predictive capability of in vitro assays, external metabolization systems like the liver S9 fraction are frequently combined with in vitro toxicity assays. While it is typical for S9 fractions that samples and testing systems are combined in the same exposure system, we propose to separate the metabolism step and toxicity measurement. This allows for a modular combination of metabolic activation by enzymes isolated from rat liver (S9) or a biotechnological alternative (ewoS9R) with in vitro bioassays that lack metabolic capacity. Benzo(a)pyrene and 2-aminoanthracene were used as model compounds to optimize the conditions for the S9 metabolic degradation/activation step. The Ames assay with Salmonella typhimurium strains TA98 and TA100 was applied to validate the set-up of decoupling the S9 activation/metabolism from the bioassay system. S9 protein concentration of 0.25 mgprotein/mL, a supplement of 0.13 mM NADPH and a pre-incubation time of 100 min are recommended for activation of samples prior to dosing them to in vitro bioassays using the regular dosing protocols of the respective bioassay. EwoS9R performed equally well as Moltox S9, which is a step forward in developing true animal-free in vitro bioassays. After pre-incubation with S9 fraction, chemicals induced bacteria revertants in both the TA98 and the TA100 assay as efficiently as the standard Ames assay. The pre-incubation of chemicals with S9 fraction could serve for a wide range of cellular in vitro assays to efficiently combine activation and toxicity measurement, which may greatly facilitate the application of these assays for chemical hazard assessment and monitoring of environmental samples.
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Affiliation(s)
- Ying Shao
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany; Key Laboratory of the Three Gorges Reservoir Eco-environment, Ministry of Education, Chongqing University, Shazheng street 174, Shapingba, 400044 Chongqing, China.
| | - Andreas Schiwy
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Department of Evolutionary Ecology and Ecotoxicology, Goethe University, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany
| | - Lisa Glauch
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Luise Henneberger
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Maria König
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Marie Mühlenbrink
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Hongxia Xiao
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany
| | - Beat Thalmann
- EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany
| | - Rita Schlichting
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Henner Hollert
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Department of Evolutionary Ecology and Ecotoxicology, Goethe University, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany
| | - Beate I Escher
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Eberhard Karls University of Tübingen, Environmental Toxicology, Centre for Applied Geosciences, 72074 Tubingen, Germany
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7
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Reed L, Jarvis IWH, Phillips DH, Arlt VM. Deletion of cytochrome P450 oxidoreductase enhances metabolism and DNA adduct formation of benzo[a]pyrene in Hepa1c1c7 cells. Mutagenesis 2020; 34:413-420. [PMID: 31612222 DOI: 10.1093/mutage/gez033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 09/19/2019] [Indexed: 11/14/2022] Open
Abstract
The environmental carcinogen benzo[a]pyrene (BaP) is presumed to exert its genotoxic effects after metabolic activation by cytochrome P450 (CYP) enzymes. However, studies using the Hepatic Reductase Null (HRN) mouse model, in which cytochrome P450 oxidoreductase (POR), the electron donor to CYP enzymes, is deleted specifically in hepatocytes, have shown that loss of hepatic POR-mediated CYP function leads to greater BaP-DNA adduct formation in livers of these mice than in wild-type (WT) mice. Here, we used CRISPR/Cas9 technology to knockout (KO) POR expression in mouse hepatoma Hepa1c1c7 cells to create an in vitro model that can mimic the HRN mouse model. Western blotting confirmed the deletion of POR in POR KO Hepa1c1c7 cells whereas expression of other components of the mixed-function oxidase system including cytochrome b5 (Cyb5) and NADH:cytochrome b5 reductase (which can also serve as electron donors to CYP enzymes), and CYP1A1 was similar in BaP-exposed WT and POR KO Hepa1c1c7 cells. BaP exposure caused cytotoxicity in WT Hepa1c1c7 cells but not in POR KO Hepa1c1c7 cells. In contrast, CYP-catalysed BaP-DNA adduct levels were ~10-fold higher in POR KO Hepa1c1c7 cells than in WT Hepa1c1c7 cells, in concordance with the presence of higher levels of BaP metabolite (e.g. BaP-7,8-dihydrodiol) in the medium of cultured BaP-exposed POR KO Hepa1c1c7 cells. As was seen in the HRN mouse model, these results suggest that Cyb5 contributes to the bioactivation of BaP in POR KO Hepa1c1c7 cells. These results indicate that CYP enzymes may play a more important role in the detoxication of BaP, as opposed to its bioactivation.
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Affiliation(s)
- Lindsay Reed
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK
| | - Ian W H Jarvis
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK.,NIHR Health Protection Research Unit in Health Impact of Environmental Hazards, King's College London in partnership with Public Health England and Imperial College London, London, UK
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK.,NIHR Health Protection Research Unit in Health Impact of Environmental Hazards, King's College London in partnership with Public Health England and Imperial College London, London, UK
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK.,NIHR Health Protection Research Unit in Health Impact of Environmental Hazards, King's College London in partnership with Public Health England and Imperial College London, London, UK
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8
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Han J, Park JC, Kang HM, Byeon E, Yoon DS, Lee MC, Sayed AEDH, Hwang UK, Lee JS. Adverse effects, expression of defense-related genes, and oxidative stress-induced MAPK pathway in the benzo[α]pyrene-exposed rotifer Brachionus rotundiformis. AQUATIC TOXICOLOGY 2019; 210:188-195. [PMID: 30870665 DOI: 10.1016/j.aquatox.2019.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 02/07/2023]
Abstract
To examine the adverse effects of the benzo[α]pyrene (B[α]P), the monogonont rotifer Brachionus rotundiformis was exposed to various concentration of B[α]P (0 [control], 1, 10, and 100 μg/L) and measured life cycle parameters (e.g., mortality, fecundity [cumulated number of offspring], and lifespan), reactive oxygen species (ROS), antioxidant enzymatic activity of glutathione S-transferase (GST). In addition, defense-related transcripts (e.g., glutathione S-transferases [GSTs], ATP binding cassette [ABCs] transporters) and Western blot analysis of mitogen-activated protein kinase (MAPK) signaling pathway were investigated in B[α]P-exposed rotifer. In this study, the total intracellular ROS level and GST activity were significantly increased (P < 0.05), while fecundity and lifespan were also significantly (P < 0.05) reduced in a concentration dependent manner in B[α]P-exposed B. rotundiformis. In addition, transcriptional regulation of GSTs and ABC transporters were significantly upregulated and downregulated (P < 0.05), respectively, suggesting that B[α]P can induce oxidative stress leading to induction of antioxidant system and detoxification mechanism. In addition to detoxification-related genes, B[α]P-exposed B. rotundiformis showed the increased levels of the p-JNK and p-p38, suggesting that B[α]P can activate MAPK signaling pathway in B. rotundiformis.
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Affiliation(s)
- Jeonghoon Han
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Jun Chul Park
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Hye-Min Kang
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Eunjin Byeon
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Deok-Seo Yoon
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Min-Chul Lee
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Alaa El-Din H Sayed
- Department of Zoology, Faculty of Science, Assiut University, 71516 Assiut, Egypt
| | - Un-Ki Hwang
- Marine Ecological Risk Assessment Center, West Sea Fisheries Research Institute, National Institute of Fisheries Science, Incheon 46083, South Korea
| | - Jae-Seong Lee
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea.
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9
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Identification of the full 26 cytochrome P450 (CYP) genes and analysis of their expression in response to benzo[α]pyrene in the marine rotifer Brachionus rotundiformis. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2018; 29:185-192. [PMID: 30551045 DOI: 10.1016/j.cbd.2018.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/01/2018] [Accepted: 12/01/2018] [Indexed: 12/31/2022]
Abstract
Cytochrome P450s (CYPs) are a large gene superfamily that are found in all living organisms. CYPs have a key role in detoxification of xenobiotics and endogenous chemicals. Although aquatic invertebrate CYPs and their detoxification mechanisms have been reported, little is known about interspecific comparison of CYPs and their detoxification mechanism in the rotifer Brachionus spp. The aim of this study was to identify the entire CYPs in the rotifer Brachionus rotundiformis (B. rotundiformis) and compare B. rotundiformis-CYPs to the previously reported CYPs in other model Brachionus spp. (B. koreanus, B. plicatilis, and B. calyciflorus). To validate the model, the rotifer, specifically Brachionus rotundiformis was exposed to various concentrations of B[α]P, which is widely used PAH xenobiotic, and analyzed gene expression in response to B[α]P. Here, in silico analysis results showed the total of 26 CYPs from the rotifer B. rotundiformis. Based on the phylogenetic analysis, the 26 B. rotundiformis-CYPs were separated into five different clans: 2, 3, 4, mitochondrial, and 46 clans in comparison to three rotifers species, B. koreanus, B. plicatilis, and B. calyciflorus. To understand the detoxification mechanisms of 26 B. rotundiformis-CYPs, we investigated transcriptional expression of 26 CYPs and found that five CYPs (CYP3045A2, CYP3045B4, CYP3045C10, CYP3049A5, and CYP3049E8) were significantly increased (P < 0.05) in response to 10 and 100 μg B[α]P. In addition, we identified the aryl hydrocarbon receptor (AhR) and aryl hydrocarbon receptor nuclear translocator (ARNT) and observed slight up-regulation of B. rotundiformis-AhR and -ARNT, indicating that these CYPs are likely associated with detoxification mechanism and could be used as potential molecular biomarkers of B[α]P in B. rotundiformis. Overall, this study will be helpful for expanding our knowledge of invertebrate CYPs on detoxification mechanisms associated with AhR signaling pathway in rotifers.
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Reed L, Arlt VM, Phillips DH. The role of cytochrome P450 enzymes in carcinogen activation and detoxication: an in vivo-in vitro paradox. Carcinogenesis 2018; 39:851-859. [PMID: 29726902 PMCID: PMC6124610 DOI: 10.1093/carcin/bgy058] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/11/2018] [Accepted: 05/02/2018] [Indexed: 02/07/2023] Open
Abstract
Many chemical carcinogens require metabolic activation via xenobiotic-metabolizing enzymes in order to exert their genotoxic effects. Evidence from numerous in-vitro studies, utilizing reconstituted systems, microsomal fractions and cultured cells, implicates cytochrome P450 enzymes as being the predominant enzymes responsible for the metabolic activation of many procarcinogens. With the development of targeted gene disruption methodologies, knockout mouse models have been generated that allow investigation of the in-vivo roles of P450 enzymes in the metabolic activation of carcinogens. This review covers studies in which five procarcinogens representing different chemical classes, benzo[a]pyrene, 4-aminobiphenyl (4-ABP), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, 2-amino-9H-pyrido[2,3-b]indole and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, have been administered to different P450 knockout mouse models. Paradoxically, while in-vitro studies using subcellular fractions enriched with P450 enzymes and their cofactors have been widely used to determine the pathways of activation of carcinogens, there is evidence from the in-vivo studies of cases where these same enzyme systems appear to have a more predominant role in carcinogen detoxication rather than activation.
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Affiliation(s)
- Lindsay Reed
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, Franklin-Wilkins Building, London, UK
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, Franklin-Wilkins Building, London, UK
- NIHR Health Protection Unit in Health Impact of Environmental Health Hazards at King’s College London in Partnership with Public Health England, London, UK
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, Franklin-Wilkins Building, London, UK
- NIHR Health Protection Unit in Health Impact of Environmental Health Hazards at King’s College London in Partnership with Public Health England, London, UK
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11
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Reed L, Mrizova I, Barta F, Indra R, Moserova M, Kopka K, Schmeiser HH, Wolf CR, Henderson CJ, Stiborova M, Phillips DH, Arlt VM. Cytochrome b 5 impacts on cytochrome P450-mediated metabolism of benzo[a]pyrene and its DNA adduct formation: studies in hepatic cytochrome b 5 /P450 reductase null (HBRN) mice. Arch Toxicol 2018; 92:1625-1638. [PMID: 29368147 PMCID: PMC5882632 DOI: 10.1007/s00204-018-2162-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/17/2018] [Indexed: 12/17/2022]
Abstract
Benzo[a]pyrene (BaP) is an environmental pollutant that, based on evidence largely from in vitro studies, exerts its genotoxic effects after metabolic activation by cytochrome P450s. In the present study, Hepatic Reductase Null (HRN) and Hepatic Cytochrome b 5 /P450 Reductase Null (HBRN) mice have been used to study the role of P450s in the metabolic activation of BaP in vivo. In HRN mice, cytochrome P450 oxidoreductase (POR), the electron donor to P450, is deleted specifically in hepatocytes. In HBRN mice the microsomal haemoprotein cytochrome b 5 , which can also act as an electron donor from cytochrome b 5 reductase to P450s, is also deleted in the liver. Wild-type (WT), HRN and HBRN mice were treated by i.p. injection with 125 mg/kg body weight BaP for 24 h. Hepatic microsomal fractions were isolated from BaP-treated and untreated mice. In vitro incubations carried out with BaP-pretreated microsomal fractions, BaP and DNA resulted in significantly higher BaP-DNA adduct formation with WT microsomal fractions compared to those from HRN or HBRN mice. Adduct formation (i.e. 10-(deoxyguanosin-N2-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-BaP [dG-N2-BPDE]) correlated with observed CYP1A activity and metabolite formation (i.e. BaP-7,8-dihydrodiol) when NADPH or NADH was used as enzymatic cofactors. BaP-DNA adduct levels (i.e. dG-N2-BPDE) in vivo were significantly higher (~ sevenfold) in liver of HRN mice than WT mice while no significant difference in adduct formation was observed in liver between HBRN and WT mice. Our results demonstrate that POR and cytochrome b 5 both modulate P450-mediated activation of BaP in vitro. However, hepatic P450 enzymes in vivo appear to be more important for BaP detoxification than its activation.
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Affiliation(s)
- Lindsay Reed
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH, UK
| | - Iveta Mrizova
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40, Prague 2, Czech Republic
| | - Frantisek Barta
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40, Prague 2, Czech Republic
| | - Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40, Prague 2, Czech Republic
| | - Michaela Moserova
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40, Prague 2, Czech Republic
| | - Klaus Kopka
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - Heinz H Schmeiser
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - C Roland Wolf
- Division of Cancer Research, Jacqui Wood Cancer Centre, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, DD1 9SY, UK
| | - Colin J Henderson
- Division of Cancer Research, Jacqui Wood Cancer Centre, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, DD1 9SY, UK
| | - Marie Stiborova
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40, Prague 2, Czech Republic
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH, UK
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH, UK.
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