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Berthelet J, Michail C, Bui LC, Le Coadou L, Sirri V, Wang L, Dulphy N, Dupret JM, Chomienne C, Guidez F, Rodrigues-Lima F. The benzene hematotoxic and reactive metabolite 1,4-benzoquinone impairs the activity of the histone methyltransferase SETD2 and causes aberrant H3K36 trimethylation (H3K36me3). Mol Pharmacol 2021; 100:283-294. [PMID: 34266924 DOI: 10.1124/molpharm.121.000303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/28/2021] [Indexed: 11/22/2022] Open
Abstract
Human SETD2 is the unique histone methyltransferase that generates H3K36me3, an epigenetic mark that plays a key role in normal hematopoiesis. Interestingly, recurrent-inactivating mutations of SETD2 and aberrant H3K36 trimethylation (H3K36me3) are increasingly reported to be involved in hematopoietic malignancies. Benzene (BZ) is an ubiquitous environmental pollutant and carcinogen that causes leukemia. The leukemogenic properties of BZ depend on its biotransformation in the bone marrow into oxidative metabolites in particular 1,4-benzoquinone (BQ). This hematotoxic metabolite can form DNA and protein adducts that result in the damage and the alteration of cellular processes. Recent studies suggest that BZ-depend leukemogenesis could depend on epigenetic perturbations notably aberrant histone methylation. We investigated whether H3K36 trimethylation by SETD2 could be impacted by BZ and its hematotoxic metabolites. Herein, we show that BQ, the major leukemogenic metabolite of BZ, inhibits irreversibly the human histone methyltransferase SETD2 resulting in decreased H3K36 trimethylation (H3K36me3). Our mechanistic studies further indicate that the BQ-dependent inactivation of SETD2 is due to covalent binding of BQ to reactive Zn-finger cysteines within the catalytic domain of the enzyme. The formation of these quinoprotein adducts results in loss of enzyme activity and protein cross-links/oligomers. Experiments conducted in hematopoietic cells confirm that exposure to BQ results in the formation of SETD2 cross-links/oligomers and concomitant loss of H3K36me3 in cells. Taken together, our data indicate that BQ, a major hematotoxic metabolite of BZ could contribute to BZ-dependent leukemogenesis by perturbing the functions of SETD2, an histone lysine methyltransferase of hematopoietic relevance. Significance Statement Benzoquinone is a major leukemogenic metabolite of benzene. Dysregulation of histone methyltransferase is involved in hematopoietic malignancies. We found that benzoquinone irreversibly impairs SETD2, a histone H3K36 methyltransferase that plays a key role in hematopoiesis. Benzoquinone forms covalent adducts on Zn-finger cysteines within the catalytic site leading to loss of activity, protein cross-links/oligomers and concomitant decrease of H3K36me3 histone mark. Our data provide evidence that a leukemogenic metabolite of benzene can impair a key epigenetic enzyme.
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Affiliation(s)
| | | | | | | | | | - Li Wang
- The First Affiliated Hospital of Chongqing Medical University, China
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Smith MT, Guyton KZ, Kleinstreuer N, Borrel A, Cardenas A, Chiu WA, Felsher DW, Gibbons CF, Goodson WH, Houck KA, Kane AB, La Merrill MA, Lebrec H, Lowe L, McHale CM, Minocherhomji S, Rieswijk L, Sandy MS, Sone H, Wang A, Zhang L, Zeise L, Fielden M. The Key Characteristics of Carcinogens: Relationship to the Hallmarks of Cancer, Relevant Biomarkers, and Assays to Measure Them. Cancer Epidemiol Biomarkers Prev 2020; 29:1887-1903. [PMID: 32152214 PMCID: PMC7483401 DOI: 10.1158/1055-9965.epi-19-1346] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/15/2020] [Accepted: 03/04/2020] [Indexed: 12/21/2022] Open
Abstract
The key characteristics (KC) of human carcinogens provide a uniform approach to evaluating mechanistic evidence in cancer hazard identification. Refinements to the approach were requested by organizations and individuals applying the KCs. We assembled an expert committee with knowledge of carcinogenesis and experience in applying the KCs in cancer hazard identification. We leveraged this expertise and examined the literature to more clearly describe each KC, identify current and emerging assays and in vivo biomarkers that can be used to measure them, and make recommendations for future assay development. We found that the KCs are clearly distinct from the Hallmarks of Cancer, that interrelationships among the KCs can be leveraged to strengthen the KC approach (and an understanding of environmental carcinogenesis), and that the KC approach is applicable to the systematic evaluation of a broad range of potential cancer hazards in vivo and in vitro We identified gaps in coverage of the KCs by current assays. Future efforts should expand the breadth, specificity, and sensitivity of validated assays and biomarkers that can measure the 10 KCs. Refinement of the KC approach will enhance and accelerate carcinogen identification, a first step in cancer prevention.See all articles in this CEBP Focus section, "Environmental Carcinogenesis: Pathways to Prevention."
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Affiliation(s)
- Martyn T Smith
- Division of Environmental Health Sciences, School of Public Health, University of California Berkeley, Berkeley, California.
| | - Kathryn Z Guyton
- Monographs Programme, International Agency for Research on Cancer, Lyon, France
| | - Nicole Kleinstreuer
- Division of Intramural Research, Biostatistics and Computational Biology Branch, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, North Carolina
- National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Alexandre Borrel
- Division of Intramural Research, Biostatistics and Computational Biology Branch, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, North Carolina
| | - Andres Cardenas
- Division of Environmental Health Sciences, School of Public Health, University of California Berkeley, Berkeley, California
| | - Weihsueh A Chiu
- Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas
| | - Dean W Felsher
- Division of Oncology, Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford, California
| | - Catherine F Gibbons
- Office of Research and Development, US Environmental Protection Agency, Washington, D.C
| | - William H Goodson
- California Pacific Medical Center Research Institute, San Francisco, California
| | - Keith A Houck
- Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Agnes B Kane
- Department of Pathology and Laboratory Medicine, Alpert Medical School, Brown University, Providence, Rhode Island
| | - Michele A La Merrill
- Department of Environmental Toxicology, University of California, Davis, California
| | - Herve Lebrec
- Comparative Biology & Safety Sciences, Amgen Research, Amgen Inc., Thousand Oaks, California
| | - Leroy Lowe
- Getting to Know Cancer, Truro, Nova Scotia, Canada
| | - Cliona M McHale
- Division of Environmental Health Sciences, School of Public Health, University of California Berkeley, Berkeley, California
| | - Sheroy Minocherhomji
- Comparative Biology & Safety Sciences, Amgen Research, Amgen Inc., Thousand Oaks, California
| | - Linda Rieswijk
- Division of Environmental Health Sciences, School of Public Health, University of California Berkeley, Berkeley, California
- Institute of Data Science, Maastricht University, Maastricht, the Netherlands
| | - Martha S Sandy
- Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Oakland, California
| | - Hideko Sone
- Yokohama University of Pharmacy and National Institute for Environmental Studies, Tsukuba Ibaraki, Japan
| | - Amy Wang
- Office of the Report on Carcinogens, Division of National Toxicology Program, The National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Luoping Zhang
- Division of Environmental Health Sciences, School of Public Health, University of California Berkeley, Berkeley, California
| | - Lauren Zeise
- Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Oakland, California
| | - Mark Fielden
- Expansion Therapeutics Inc, San Diego, California
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3
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Luijten M, Ball NS, Dearfield KL, Gollapudi BB, Johnson GE, Madia F, Peel L, Pfuhler S, Settivari RS, ter Burg W, White PA, van Benthem J. Utility of a next generation framework for assessment of genomic damage: A case study using the industrial chemical benzene. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:94-113. [PMID: 31709603 PMCID: PMC6972600 DOI: 10.1002/em.22346] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 10/31/2019] [Accepted: 11/06/2019] [Indexed: 05/22/2023]
Abstract
We recently published a next generation framework for assessing the risk of genomic damage via exposure to chemical substances. The framework entails a systematic approach with the aim to quantify risk levels for substances that induce genomic damage contributing to human adverse health outcomes. Here, we evaluated the utility of the framework for assessing the risk for industrial chemicals, using the case of benzene. Benzene is a well-studied substance that is generally considered a genotoxic carcinogen and is known to cause leukemia. The case study limits its focus on occupational and general population health as it relates to benzene exposure. Using the framework as guidance, available data on benzene considered relevant for assessment of genetic damage were collected. Based on these data, we were able to conduct quantitative analyses for relevant data sets to estimate acceptable exposure levels and to characterize the risk of genetic damage. Key observations include the need for robust exposure assessments, the importance of information on toxicokinetic properties, and the benefits of cheminformatics. The framework points to the need for further improvement on understanding of the mechanism(s) of action involved, which would also provide support for the use of targeted tests rather than a prescribed set of assays. Overall, this case study demonstrates the utility of the next generation framework to quantitatively model human risk on the basis of genetic damage, thereby enabling a new, innovative risk assessment concept. Environ. Mol. Mutagen. 61:94-113, 2020. © 2019 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.
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Affiliation(s)
- Mirjam Luijten
- Centre for Health ProtectionNational Institute for Public Health and the Environment (RIVM)BilthovenThe Netherlands
| | | | | | | | - George E. Johnson
- Swansea University Medical School, Swansea UniversitySwanseaUnited Kingdom
| | - Federica Madia
- European Commission, Joint Research Centre (JRC)IspraItaly
| | - Lauren Peel
- Health and Environmental Sciences InstituteWashingtonDistrict of Columbia
| | | | | | - Wouter ter Burg
- Centre for Safety of Substances and ProductsNational Institute for Public Health and the Environment (RIVM)BilthovenThe Netherlands
| | - Paul A. White
- Department of BiologyUniversity of OttawaOttawaOntarioCanada
| | - Jan van Benthem
- Centre for Health ProtectionNational Institute for Public Health and the Environment (RIVM)BilthovenThe Netherlands
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4
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Atkin ND, Raimer HM, Wang YH. Broken by the Cut: A Journey into the Role of Topoisomerase II in DNA Fragility. Genes (Basel) 2019; 10:E791. [PMID: 31614754 PMCID: PMC6826763 DOI: 10.3390/genes10100791] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 10/05/2019] [Accepted: 10/10/2019] [Indexed: 02/07/2023] Open
Abstract
DNA topoisomerase II (TOP2) plays a critical role in many processes such as replication and transcription, where it resolves DNA structures and relieves torsional stress. Recent evidence demonstrated the association of TOP2 with topologically associated domains (TAD) boundaries and CCCTC-binding factor (CTCF) binding sites. At these sites, TOP2 promotes interactions between enhancers and gene promoters, and relieves torsional stress that accumulates at these physical barriers. Interestingly, in executing its enzymatic function, TOP2 contributes to DNA fragility through re-ligation failure, which results in persistent DNA breaks when unrepaired or illegitimately repaired. Here, we discuss the biological processes for which TOP2 is required and the steps at which it can introduce DNA breaks. We describe the repair processes that follow removal of TOP2 adducts and the resultant broken DNA ends, and present how these processes can contribute to disease-associated mutations. Furthermore, we examine the involvement of TOP2-induced breaks in the formation of oncogenic translocations of leukemia and papillary thyroid cancer, as well as the role of TOP2 and proteins which repair TOP2 adducts in other diseases. The participation of TOP2 in generating persistent DNA breaks and leading to diseases such as cancer, could have an impact on disease treatment and prevention.
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Affiliation(s)
- Naomi D Atkin
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA.
| | - Heather M Raimer
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Yuh-Hwa Wang
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA.
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5
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Duval R, Bui LC, Mathieu C, Nian Q, Berthelet J, Xu X, Haddad I, Vinh J, Dupret JM, Busi F, Guidez F, Chomienne C, Rodrigues-Lima F. Benzoquinone, a leukemogenic metabolite of benzene, catalytically inhibits the protein tyrosine phosphatase PTPN2 and alters STAT1 signaling. J Biol Chem 2019; 294:12483-12494. [PMID: 31248982 DOI: 10.1074/jbc.ra119.008666] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 06/21/2019] [Indexed: 12/12/2022] Open
Abstract
Protein tyrosine phosphatase, nonreceptor type 2 (PTPN2) is mainly expressed in hematopoietic cells, where it negatively regulates growth factor and cytokine signaling. PTPN2 is an important regulator of hematopoiesis and immune/inflammatory responses, as evidenced by loss-of-function mutations of PTPN2 in leukemia and lymphoma and knockout mice studies. Benzene is an environmental chemical that causes hematological malignancies, and its hematotoxicity arises from its bioactivation in the bone marrow to electrophilic metabolites, notably 1,4-benzoquinone, a major hematotoxic benzene metabolite. Although the molecular bases for benzene-induced leukemia are not well-understood, it has been suggested that benzene metabolites alter topoisomerases II function and thereby significantly contribute to leukemogenesis. However, several studies indicate that benzene and its hematotoxic metabolites may also promote the leukemogenic process by reacting with other targets and pathways. Interestingly, alterations of cell-signaling pathways, such as Janus kinase (JAK)/signal transducer and activator of transcription (STAT), have been proposed to contribute to benzene-induced malignant blood diseases. We show here that 1,4-benzoquinone directly impairs PTPN2 activity. Mechanistic and kinetic experiments with purified human PTPN2 indicated that this impairment results from the irreversible formation (k inact = 645 m-1·s-1) of a covalent 1,4-benzoquinone adduct at the catalytic cysteine residue of the enzyme. Accordingly, cell experiments revealed that 1,4-benzoquinone exposure irreversibly inhibits cellular PTPN2 and concomitantly increases tyrosine phosphorylation of STAT1 and expression of STAT1-regulated genes. Our results provide molecular and cellular evidence that 1,4-benzoquinone covalently modifies key signaling enzymes, implicating it in benzene-induced malignant blood diseases.
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Affiliation(s)
- Romain Duval
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Linh-Chi Bui
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Cécile Mathieu
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Qing Nian
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | | | - Ximing Xu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Iman Haddad
- ESPCI Paris, PSL Université, USR 3149, CNRS, F-75005 Paris, France
| | - Joelle Vinh
- ESPCI Paris, PSL Université, USR 3149, CNRS, F-75005 Paris, France
| | | | - Florent Busi
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Fabien Guidez
- Université de Paris, Institut de Recherche Saint-Louis, UMRS 1131, INSERM, F-75010 Paris, France
| | - Christine Chomienne
- Université de Paris, Institut de Recherche Saint-Louis, UMRS 1131, INSERM, F-75010 Paris, France; Service de Biologie Cellulaire, Assistance Publique des Hôpitaux de Paris (AP-HP), Hôpital Saint Louis, F-75010 Paris, France
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6
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Balakrishnan S, Hasegawa L, Eastmond DA. The role of urinary pH in o-phenylphenol-induced cytotoxicity and chromosomal damage in the bladders of F344 rats. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2016; 57:210-219. [PMID: 26919225 DOI: 10.1002/em.22002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 01/14/2016] [Accepted: 01/15/2016] [Indexed: 06/05/2023]
Abstract
o-Phenylphenol (OPP) is a widely used fungicide and antibacterial agent that at high doses has been shown to cause bladder cancer in male F344 rats. The mechanisms underlying OPP-induced bladder carcinogenicity remain unclear but it has been proposed that a non-enzymatic pH-dependent autoxidation of phenylhydroquinone (PHQ), a primary metabolite of OPP, may be a key step in OPP-induced rat bladder carcinogenesis. To investigate this mechanism and to provide insights into the potential human health relevance of OPP-induced cancer, a series of in vitro and in vivo experiments were conducted. In human lymphoblastoid TK-6 cells and rat bladder epithelial NBT-II cells, strong increases in cytotoxicity were seen at a constant concentration of PHQ by increasing the buffer pH as well as by increasing concentrations of PHQ at a constant pH. In in vivo studies, male rats were administered OPP (4,000 and 8,000 ppm) in a diet supplemented with either 1% ammonium chloride or 3% sodium bicarbonate to produce acidic and alkaline urinary pH, respectively. Significant increases in cell proliferation as detected by 5-bromo-2'-deoxyuridine incorporation and micronucleus formation were seen in the bladder cells of OPP-treated rats with neutral or alkaline urinary pH but not in animals with the acidified urine. The results from these in vitro and in vivo studies provide support for the autoxidation hypothesis of bioactivation, and provide additional evidence that urinary pH can significantly influence the genotoxicity and carcinogenicity of this important agent.
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Affiliation(s)
- S Balakrishnan
- Environmental Toxicology Graduate Program, University of California, Riverside, California
| | - L Hasegawa
- Environmental Toxicology Graduate Program, University of California, Riverside, California
| | - D A Eastmond
- Environmental Toxicology Graduate Program, University of California, Riverside, California
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7
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Lymphohematopoietic cancers induced by chemicals and other agents and their implications for risk evaluation: An overview. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 761:40-64. [PMID: 24731989 DOI: 10.1016/j.mrrev.2014.04.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 04/02/2014] [Accepted: 04/03/2014] [Indexed: 12/13/2022]
Abstract
Lymphohematopoietic neoplasia are one of the most common types of cancer induced by therapeutic and environmental agents. Of the more than 100 human carcinogens identified by the International Agency for Research on Cancer, approximately 25% induce leukemias or lymphomas. The objective of this review is to provide an introduction into the origins and mechanisms underlying lymphohematopoietic cancers induced by xenobiotics in humans with an emphasis on acute myeloid leukemia, and discuss the implications of this information for risk assessment. Among the agents causing lymphohematopoietic cancers, a number of patterns were observed. Most physical and chemical leukemia-inducing agents such as the therapeutic alkylating agents, topoisomerase II inhibitors, and ionizing radiation induce mainly acute myeloid leukemia through DNA-damaging mechanisms that result in either gene or chromosomal mutations. In contrast, biological agents and a few immunosuppressive chemicals induce primarily lymphoid neoplasms through mechanisms that involve alterations in immune response. Among the environmental agents examined, benzene was clearly associated with acute myeloid leukemia in humans, with increasing but still limited evidence for an association with lymphoid neoplasms. Ethylene oxide and 1,3-butadiene were linked primarily to lymphoid cancers. Although the association between formaldehyde and leukemia remains controversial, several recent evaluations have indicated a potential link between formaldehyde and acute myeloid leukemia. The four environmental agents examined in detail were all genotoxic, inducing gene mutations, chromosomal alterations, and/or micronuclei in vivo. Although it is clear that rapid progress has been made in recent years in our understanding of leukemogenesis, many questions remain for future research regarding chemically induced leukemias and lymphomas, including the mechanisms by which the environmental agents reviewed here induce these diseases and the risks associated with exposures to such agents.
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8
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Siew EL, Chan KM, Williams GT, Ross D, Inayat-Hussain SH. Protection of hydroquinone-induced apoptosis by downregulation of Fau is mediated by NQO1. Free Radic Biol Med 2012; 53:1616-24. [PMID: 22687461 DOI: 10.1016/j.freeradbiomed.2012.05.046] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 05/26/2012] [Accepted: 05/30/2012] [Indexed: 01/11/2023]
Abstract
The Fau gene (Finkel-Biskis-Reilly murine sarcoma virus (FBR-MuSV)-associated ubiquitously expressed gene) was identified as a potential tumor suppressor gene using a forward genetics approach. Downregulation of Fau by overexpression of its reverse sequence has been shown to inhibit apoptosis induced by DNA-damaging agents. To address a potential role of Fau in benzene toxicity, we investigated the apoptotic effects of hydroquinone (HQ), a major benzene metabolite, in W7.2 mouse thymoma cells transfected with either a plasmid construct expressing the antisense sequence of Fau (rfau) or the empty vector (pcDNA3.1) as a control. HQ induced apoptosis via increased production of reactive oxygen species and DNA damage, measured using dihydroethidine (HE) staining and alkaline Comet assay, respectively, in W7.2 pcDNA3.1 cells. In contrast, when Fau was downregulated by the antisense sequence in W7.2 rfau cells, HQ treatment did not cause DNA damage and oxidative stress and these cells were markedly more resistant to HQ-induced apoptosis. Further investigation revealed that there was an upregulation of NAD(P)H: quinone oxidoreductase 1 (NQO1), a detoxification enzyme for benzene-derived quinones, in W7.2 rfau cells. Compromising cellular NQO1 by use of a specific mechanism-based inhibitor (MAC 220) and NQO1 siRNA resensitized W7.2 rfau cells to HQ-induced apoptosis. Silencing of Fau in W7.2 wild-type cells resulted in increased levels of NQO1, confirming that downregulation of Fau results in NQO1 upregulation which protects against HQ-induced apoptosis.
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Affiliation(s)
- E L Siew
- Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia
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9
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McHale CM, Zhang L, Smith MT. Current understanding of the mechanism of benzene-induced leukemia in humans: implications for risk assessment. Carcinogenesis 2012; 33:240-52. [PMID: 22166497 PMCID: PMC3271273 DOI: 10.1093/carcin/bgr297] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 11/21/2011] [Accepted: 12/07/2011] [Indexed: 01/01/2023] Open
Abstract
Benzene causes acute myeloid leukemia and probably other hematological malignancies. As benzene also causes hematotoxicity even in workers exposed to levels below the US permissible occupational exposure limit of 1 part per million, further assessment of the health risks associated with its exposure, particularly at low levels, is needed. Here, we describe the probable mechanism by which benzene induces leukemia involving the targeting of critical genes and pathways through the induction of genetic, chromosomal or epigenetic abnormalities and genomic instability, in a hematopoietic stem cell (HSC); stromal cell dysregulation; apoptosis of HSCs and stromal cells and altered proliferation and differentiation of HSCs. These effects modulated by benzene-induced oxidative stress, aryl hydrocarbon receptor dysregulation and reduced immunosurveillance, lead to the generation of leukemic stem cells and subsequent clonal evolution to leukemia. A mode of action (MOA) approach to the risk assessment of benzene was recently proposed. This approach is limited, however, by the challenges of defining a simple stochastic MOA of benzene-induced leukemogenesis and of identifying relevant and quantifiable parameters associated with potential key events. An alternative risk assessment approach is the application of toxicogenomics and systems biology in human populations, animals and in vitro models of the HSC stem cell niche, exposed to a range of levels of benzene. These approaches will inform our understanding of the mechanisms of benzene toxicity and identify additional biomarkers of exposure, early effect and susceptibility useful for risk assessment.
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Affiliation(s)
| | | | - Martyn T. Smith
- Division of Environmental Health Sciences, Genes and Environment Laboratory, School of Public Health, University of California, Berkeley, CA 94720-7356, USA
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10
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Tung EWY, Philbrook NA, Macdonald KDD, Winn LM. DNA double-strand breaks and DNA recombination in benzene metabolite-induced genotoxicity. Toxicol Sci 2012; 126:569-77. [PMID: 22247006 DOI: 10.1093/toxsci/kfs001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In utero exposure to environmental carcinogens, including the ubiquitous pollutant benzene, may cause DNA damage in the fetus, leading to an increased risk for the development of childhood cancer. Benzene metabolite-induced DNA double-strand breaks (DSBs) may undergo erroneous repair, leading to chromosomal aberrations including chromosomal inversions and translocations. In this study, fetal murine hematopoietic cells from pZK1 transgenic mice were exposed to p-benzoquinone (BQ), a toxic metabolite of benzene, and assessed for DNA recombination, DNA damage including DNA DSBs as measured by γ-H2A.X foci and oxidative DNA damage, and reactive oxygen species (ROS) production. The pZK1 transgenic mouse model contains a DNA construct allowing for the detection of intrachromosomal recombination events. Using this model, a significant increase in recombination was observed following exposure to BQ (25 and 50μM) at various time points. Additionally, increased γ-H2A.X foci were observed following exposure to 25μM BQ for 30 min, 45 min, and 1 h, whereas this exposure did not significantly increase oxidative DNA damage. Pretreatment with 400 U/ml polyethylene glycol-conjugated-catalase attenuated increases in DNA recombination as compared with treatment with BQ alone. An increase in ROS production (30 min and 1 h), as measured by dichlorodihydrofluorescein diacetate fluorescence, was also observed following exposure to 25μM BQ. These studies indicate that BQ is able to induce DNA damage and recombination in fetal liver cells and that ROS may be important in the mechanism of toxicity.
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Affiliation(s)
- Emily W Y Tung
- Department of Biomedical and Molecular Sciences, Queen's University, Room 557, Botterell Hall, Kingston, Ontario K7L 3N6, Canada
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11
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Gurbani D, Kukshal V, Laubenthal J, Kumar A, Pandey A, Tripathi S, Arora A, Jain SK, Ramachandran R, Anderson D, Dhawan A. Mechanism of inhibition of the ATPase domain of human topoisomerase IIα by 1,4-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, and 9,10-phenanthroquinone. Toxicol Sci 2012; 126:372-90. [PMID: 22218491 DOI: 10.1093/toxsci/kfr345] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The inhibition of human topoisomerase IIα (Hu-TopoIIα), a major enzyme involved in maintaining DNA topology, repair, and chromosome condensation/decondensation results in loss of genomic integrity. In the present study, the inhibition of ATPase domain of Hu-TopoIIα as a possible mechanism of genotoxicity of 1,4-benzoquinone (BQ), hydroquinone (HQ), naphthoquinone (1,2-NQ and 1,4-NQ), and 9,10-phenanthroquinone (9,10-PQ) was investigated. In silico modeling predicted that 1,4-BQ, 1,2-NQ, 1,4-NQ, and 9,10-PQ could interact with Ser-148, Ser-149, Asn-150, and Asn-91 residues of the ATPase domain of Hu-TopoIIα. Biochemical inhibition assays with the purified ATPase domain of Hu-TopoIIα revealed that 1,4-BQ is the most potent inhibitor followed by 1,4-NQ > 1,2-NQ > 9,10-PQ > HQ. Ligand-binding studies using isothermal titration calorimetry revealed that 1,4-BQ, HQ, 1,4-NQ, 1,2-NQ, and 9,10-PQ enter into four sequentially binding site models inside the domain. 1,4-BQ exhibited the strongest binding, followed by 1,4-NQ > 1,2-NQ > 9,10-PQ > HQ, as revealed by their average K(d) values. The cellular fate of such inhibition was further evidenced by an increase in the number of Hu-TopoIIα-DNA cleavage complexes in the human lung epithelial cells (BEAS-2B) using trapped in agarose DNA immunostaining (TARDIS) assay, which utilizes antibody specific for Hu-TopoIIα. Furthermore, the increase in γ-H2A.X levels quantitated by flow cytometry and visualized by immunofluorescence microscopy illustrated that accumulation of DNA double-strand breaks inside the cells can be attributed to the inhibition of Hu-TopoIIα. These findings collectively suggest that 1,4-BQ, 1,2-NQ, 1,4-NQ, and 9,10-PQ inhibit the ATPase domain and potentially result in Hu-TopoIIα-mediated clastogenic and leukemogenic events.
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Affiliation(s)
- Deepak Gurbani
- Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India
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12
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Nishikawa T, Miyahara E, Horiuchi M, Izumo K, Okamoto Y, Kawai Y, Kawano Y, Takeuchi T. Benzene metabolite 1,2,4-benzenetriol induces halogenated DNA and tyrosines representing halogenative stress in the HL-60 human myeloid cell line. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:62-67. [PMID: 21859636 PMCID: PMC3261936 DOI: 10.1289/ehp.1103437] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 08/22/2011] [Indexed: 05/31/2023]
Abstract
BACKGROUND Although benzene is known to be myelotoxic and to cause myeloid leukemia in humans, the mechanism has not been elucidated. OBJECTIVES We focused on 1,2,4-benzenetriol (BT), a benzene metabolite that generates reactive oxygen species (ROS) by autoxidation, to investigate the toxicity of benzene leading to leukemogenesis. METHODS After exposing HL-60 human myeloid cells to BT, we investigated the cellular effects, including apoptosis, ROS generation, DNA damage, and protein damage. We also investigated how the cellular effects of BT were modified by hydrogen peroxide (H2O2) scavenger catalase, hypochlorous acid (HOCl) scavenger methionine, and 4-aminobenzoic acid hydrazide (ABAH), a myeloperoxidase (MPO)-specific inhibitor. RESULTS BT increased the levels of apoptosis and ROS, including superoxide (O2•-), H2O2, HOCl, and the hydroxyl radical (•OH). Catalase, ABAH, and methionine each inhibited the increased apoptosis caused by BT, and catalase and ABAH inhibited increases in HOCl and •OH. Although BT exposure increased halogenated DNA, this increase was inhibited by catalase, methionine, and ABAH. BT exposure also increased the amount of halogenated tyrosines; however, it did not increase 8-oxo-deoxyguanosine. CONCLUSIONS We suggest that BT increases H2O2 intracellularly; this H2O2 is metabolized to HOCl by MPO, and this HOCl results in possibly cytotoxic binding of chlorine to DNA. Because myeloid cells copiously express MPO and because halogenated DNA may induce both genetic and epigenetic changes that contribute to carcinogenesis, halogenative stress may account for benzene-induced bone marrow disorders and myeloid leukemia.
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Affiliation(s)
- Takuro Nishikawa
- Department of Environmental Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuraga-oka, Kagoshima, Japan.
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North M, Tandon VJ, Thomas R, Loguinov A, Gerlovina I, Hubbard AE, Zhang L, Smith MT, Vulpe CD. Genome-wide functional profiling reveals genes required for tolerance to benzene metabolites in yeast. PLoS One 2011; 6:e24205. [PMID: 21912624 PMCID: PMC3166172 DOI: 10.1371/journal.pone.0024205] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 08/06/2011] [Indexed: 11/18/2022] Open
Abstract
Benzene is a ubiquitous environmental contaminant and is widely used in industry. Exposure to benzene causes a number of serious health problems, including blood disorders and leukemia. Benzene undergoes complex metabolism in humans, making mechanistic determination of benzene toxicity difficult. We used a functional genomics approach to identify the genes that modulate the cellular toxicity of three of the phenolic metabolites of benzene, hydroquinone (HQ), catechol (CAT) and 1,2,4-benzenetriol (BT), in the model eukaryote Saccharomyces cerevisiae. Benzene metabolites generate oxidative and cytoskeletal stress, and tolerance requires correct regulation of iron homeostasis and the vacuolar ATPase. We have identified a conserved bZIP transcription factor, Yap3p, as important for a HQ-specific response pathway, as well as two genes that encode putative NAD(P)H:quinone oxidoreductases, PST2 and YCP4. Many of the yeast genes identified have human orthologs that may modulate human benzene toxicity in a similar manner and could play a role in benzene exposure-related disease.
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Affiliation(s)
- Matthew North
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California, United States of America
| | - Vickram J. Tandon
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California, United States of America
| | - Reuben Thomas
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California, United States of America
| | - Alex Loguinov
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California, United States of America
| | - Inna Gerlovina
- Division of Biostatistics, School of Public Health, University of California, Berkeley, California, United States of America
| | - Alan E. Hubbard
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California, United States of America
- Division of Biostatistics, School of Public Health, University of California, Berkeley, California, United States of America
| | - Luoping Zhang
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California, United States of America
| | - Martyn T. Smith
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California, United States of America
| | - Chris D. Vulpe
- Department of Nutritional Science and Toxicology, University of California, Berkeley, California, United States of America
- * E-mail:
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Ji Z, Zhang L, Peng V, Ren X, McHale CM, Smith MT. A comparison of the cytogenetic alterations and global DNA hypomethylation induced by the benzene metabolite, hydroquinone, with those induced by melphalan and etoposide. Leukemia 2010; 24:986-91. [PMID: 20339439 PMCID: PMC4353491 DOI: 10.1038/leu.2010.43] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Revised: 01/07/2010] [Accepted: 01/29/2010] [Indexed: 12/26/2022]
Abstract
Specific cytogenetic alterations and changes in DNA methylation are involved in leukemogenesis. Benzene, an established human leukemogen, is known to induce cytogenetic changes through its active metabolites including hydroquinone (HQ), but the specific alterations have not been fully characterized. Global DNA hypomethylation was reported in a population exposed to benzene, but has not been confirmed in vitro. In this study, we examined cytogenetic changes in chromosomes 5, 7, 8, 11 and 21, and global DNA methylation in human TK6 lymphoblastoid cells treated with HQ for 48 h, and compared the HQ-induced alterations with those induced by two well-known leukemogens, melphalan, an alkylating agent, and etoposide, a DNA topoisomerase II inhibitor. We found that rather than inducing cytogenetic alterations distinct from those induced by melphalan and etoposide, HQ induced alterations characteristic of each agent. HQ induced global DNA hypomethylation at a level intermediate to melphalan (no effect) and etoposide (potent effect). These results suggest that HQ may act similar to an alkylating agent and also similar to a DNA topoisomerase II inhibitor in living cells, both of which may be potential mechanisms of benzene toxicity. In addition to cytogenetic changes, global DNA hypomethylation may be another mechanism underlying the leukemogenicity of benzene.
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MESH Headings
- Antineoplastic Agents, Alkylating/pharmacology
- Antineoplastic Agents, Phytogenic/pharmacology
- Cells, Cultured
- Chromosomes, Human/drug effects
- Chromosomes, Human/genetics
- DNA Methylation/drug effects
- Etoposide/pharmacology
- Humans
- Hydroquinones/pharmacology
- In Situ Hybridization, Fluorescence
- Leukemia, Myeloid, Acute/drug therapy
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/pathology
- Lymphocytes/drug effects
- Melphalan/pharmacology
- Mutagens/pharmacology
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Affiliation(s)
- Z Ji
- Division of Environmental Health Sciences, School of Public Health, University of California at Berkeley, Berkeley, CA 94720-7360, USA
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15
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Mondrala S, Eastmond DA. Topoisomerase II inhibition by the bioactivated benzene metabolite hydroquinone involves multiple mechanisms. Chem Biol Interact 2010; 184:259-68. [DOI: 10.1016/j.cbi.2009.12.023] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2009] [Revised: 12/07/2009] [Accepted: 12/15/2009] [Indexed: 11/26/2022]
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16
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Lachenmeier DW, Kuballa T, Reusch H, Sproll C, Kersting M, Alexy U. Benzene in infant carrot juice: Further insight into formation mechanism and risk assessment including consumption data from the DONALD study. Food Chem Toxicol 2010; 48:291-7. [DOI: 10.1016/j.fct.2009.10.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 09/25/2009] [Accepted: 10/08/2009] [Indexed: 10/20/2022]
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Abstract
Benzene is a ubiquitous chemical in our environment that causes acute leukemia and probably other hematological cancers. Evidence for an association with childhood leukemia is growing. Exposure to benzene can lead to multiple alterations that contribute to the leukemogenic process, indicating a multimodal mechanism of action. Research is needed to elucidate the different roles of multiple metabolites in benzene toxicity and the pathways that lead to their formation. Studies to date have identified a number of polymorphisms in candidate genes that confer susceptibility to benzene hematotoxicity. However, a genome-wide study is needed to truly assess the role of genetic variation in susceptibility. Benzene affects the blood-forming system at low levels of occupational exposure, and there is no evidence of a threshold. There is probably no safe level of exposure to benzene, and all exposures constitute some risk in a linear, if not supralinear, and additive fashion.
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Affiliation(s)
- Martyn T Smith
- Superfund Research Program, Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California 94720-7356, USA.
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18
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Ross D, Zhou H. Relationships between metabolic and non-metabolic susceptibility factors in benzene toxicity. Chem Biol Interact 2009; 184:222-8. [PMID: 19941840 DOI: 10.1016/j.cbi.2009.11.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 11/17/2009] [Accepted: 11/17/2009] [Indexed: 01/26/2023]
Abstract
Reactive metabolites formed from benzene include benzene oxide, trans,trans muconaldehyde, quinones, thiol adducts, phenolic metabolites and oxygen radicals. Susceptibility to the toxic effects of benzene has been suggested to occur partly because of polymorphisms in enzymes involved in benzene metabolism which include cytochrome P450 2E1, epoxide hydrolases, myeloperoxidase, glutathione-S-transferases and quinone reductases. However, susceptibility factors not directly linked to benzene metabolism have also been associated with its toxicity and include p53, proteins involved in DNA repair, genomic stability and expression of cytokines and/or cell adhesion molecules. In this work, we examine potential relationships between metabolic and non-metabolic susceptibility factors using the enzyme NAD(P)H:quinone oxidoreductase (NQO1) as an example. NQO1 may also impact pathways in addition to metabolism of quinones due to protein-protein interactions or other mechanisms related to NQO1 activity. NQO1 has been implicated in stabilizing p53 and in maintaining microtubule integrity. Inhibition or knockdown of NQO1 in bone marrow endothelial cells has been found to lead to deficiencies of E-selectin, ICAM-1 and VCAM-1 adhesion molecule expression after TNFalpha stimulation. These examples illustrate how the metabolic susceptibility factor NQO1 may influence non-metabolic susceptibility pathways for benzene toxicity.
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Affiliation(s)
- David Ross
- Department of Pharmaceutical Sciences, School of Pharmacy and Cancer Center, University of Colorado Anschutz Medical Campus, C238-P15 Research 2, 12700 East 19th Avenue, Aurora, CO 80045, United States.
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19
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Ji Z, Zhang L, Guo W, McHale CM, Smith MT. The benzene metabolite, hydroquinone and etoposide both induce endoreduplication in human lymphoblastoid TK6 cells. Mutagenesis 2009; 24:367-72. [PMID: 19491217 PMCID: PMC2701990 DOI: 10.1093/mutage/gep018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 04/09/2009] [Accepted: 04/24/2009] [Indexed: 01/09/2023] Open
Abstract
Both occupational exposure to the leukemogen benzene and in vitro exposure to its metabolite hydroquinone (HQ) lead to the induction of numerical and structural chromosome changes. Several studies have shown that HQ can form DNA adducts, disrupt microtubule assembly and inhibit DNA topoisomerase II (topo II) activity. As these are potential mechanisms underlying endoreduplication (END), a phenomenon that involves DNA amplification without corresponding cell division, we hypothesized that HQ could cause END. We measured END in the human lymphoblastoid cell line, TK6, treated with HQ (0-20 microM) and etoposide (0-0.2 microM) for 48 h. Etoposide was used as a positive control as it is a topo II poison and established human leukemogen that has previously been shown to induce END in Chinese hamster ovary cells. Both HQ and etoposide significantly induced END in a dose-dependent manner (P(trend) < 0.0001 and P(trend) = 0.0003, respectively). Since END may underlie the acquisition of high chromosome numbers by tumour cells, it may play a role in inducing genomic instability and subsequent carcinogenesis from HQ and etoposide. In order to further explore the cytogenetic effects of HQ and etoposide, we also examined specific structural changes. HQ did not induce translocations of chromosome 11 [t(11;?)] but significantly induced translocations of chromosome 21 [t(21;?)] and structural chromosome aberrations (SCA) (P(trend) = 0.0415 and P(trend) < 0.0001, respectively). Etoposide potently induced all these structural changes (P(trend) < 0.0001). The lack of an effect of HQ on t(11;?) and the reduced ability of HQ to induce t(21;?) and SCA, compared with etoposide, further suggests that HQ acts primarily as a topo II catalytic inhibitor rather than as a topo II poison in intact human cells.
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Affiliation(s)
| | | | | | | | - Martyn T. Smith
- Department of Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA 94720, USA
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20
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Toyooka T, Ibuki Y. Cigarette sidestream smoke induces phosphorylated histone H2AX. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2009; 676:34-40. [DOI: 10.1016/j.mrgentox.2009.03.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 02/13/2009] [Accepted: 03/14/2009] [Indexed: 12/18/2022]
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21
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Wilbur S, Wohlers D, Paikoff S, Keith LS, Faroon O. ATSDR evaluation of health effects of benzene and relevance to public health. Toxicol Ind Health 2009; 24:263-398. [PMID: 19022880 DOI: 10.1177/0748233708090910] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites that have the greatest public health impact. These profiles comprehensively summarize toxicological and environmental information. This article constitutes the release of portions of the Toxicological Profile for Benzene. The primary purpose of this article is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective on the toxicology of benzene. It contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health.
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Affiliation(s)
- S Wilbur
- Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Atlanta, Georgia 30333, USA.
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22
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Ishihama M, Toyooka T, Ibuki Y. Generation of phosphorylated histone H2AX by benzene metabolites. Toxicol In Vitro 2008; 22:1861-8. [DOI: 10.1016/j.tiv.2008.09.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 08/25/2008] [Accepted: 09/08/2008] [Indexed: 12/22/2022]
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23
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Tea flavanols inhibit cell growth and DNA topoisomerase II activity and induce endoreduplication in cultured Chinese hamster cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2008; 654:8-12. [DOI: 10.1016/j.mrgentox.2008.03.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 02/08/2008] [Accepted: 03/28/2008] [Indexed: 01/22/2023]
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24
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Huang CP, Fang WH, Lin LI, Chiou RY, Kan LS, Chi NH, Chen YR, Lin TY, Lin SB. Anticancer activity of botanical alkyl hydroquinones attributed to topoisomerase II poisoning. Toxicol Appl Pharmacol 2008; 227:331-8. [DOI: 10.1016/j.taap.2007.11.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2007] [Revised: 11/12/2007] [Accepted: 11/14/2007] [Indexed: 10/22/2022]
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Luo L, Jiang L, Geng C, Cao J, Zhong L. Hydroquinone-induced genotoxicity and oxidative DNA damage in HepG2 cells. Chem Biol Interact 2008; 173:1-8. [PMID: 18358459 DOI: 10.1016/j.cbi.2008.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 02/03/2008] [Accepted: 02/04/2008] [Indexed: 10/22/2022]
Abstract
Hydroquinone (HQ) is used as an antioxidant in rubber industry and as a developing agent in photography. HQ is also an intermediate in the manufacture of rubber, food antioxidant and monomer inhibitor. However, the mechanisms of the effects, in particular those related to its genotoxicity in humans, are not well understood. The aim of this study was to assess the genotoxic effects of HQ and to identify and clarify the mechanisms, using human hepatoma HepG2 cells. DNA strand breaks and DNA-protein crosslinks (DPC) were measured by the proteinase K-modified alkaline single cell gel electrophoresis (SCGE) assays. Using the SCGE assay, a significant dose-dependent increment in DNA migration was detected at concentrations of HQ (6.25-25 microM); but at the higher tested concentrations (50 microM), a reduction in the migration compared to the maximum migration at 25 microM was observed. Post-incubation with proteinase K significantly increased DNA migration in cells exposed to higher concentrations of HQ (50 microM). A significant increase of the frequency of micronuclei was found in the range from 12.5 to 50 microM in the micronucleus test (MNT). The data suggested that HQ caused DNA strand breaks, DPC and chromosome breaks. To elucidate the oxidative DNA damage mechanism, the 2,7-dichlorofluorescein diacetate (DCFH-DA) and o-phthalaldehyde (OPT) were chosen to monitor the levels of reactive oxygen species (ROS) and glutathione (GSH), respectively. The present study showed that HQ induced the increased levels of ROS and depletion of GSH in HepG2 cells, the doses being 25-50 and 6.25-50 microM, respectively. Moreover, HQ significantly caused 8-hydroxydeoxyguanosine (8-OHdG) formation in HepG2 cells at concentrations from 12.5 to 50 microM. All these results demonstrate that HQ exerts genotoxic effects in HepG2 cells, probably through DNA damage by oxidative stress. GSH, as a main intracellular antioxidant, is responsible for cellular defense against HQ-induced DNA damage.
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Affiliation(s)
- Lihan Luo
- Department of Toxicology, Dalian Medical University, No. 9, West Segment of South lvshun Road, Dalian 116044, Liaoning, China
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Abstract
Benzene-induced acute myeloid leukemia (AML) is considered a secondary form of AML, based both in theory and on limited cohort observations. Its latency, cytogenetic aberrations, and clinical features are thought similar to, or identical with, AML resulting from the use of modern day cytotoxic agents for chemotherapy and immunotherapy. Although distinction between secondary AML and the far more common de novo AML is difficult to establish with certainty in any given case, latency from toxic therapeutic and environmental exposure and certain clinical and pathological features generally separate these two entities. AML is the only human neoplasm proven to be potentially caused by benzene, which actually is an obsolete form of chemotherapy. Despite many years of environmental regulation, alleged toxic exposure to this ubiquitous chemical has become an expanding area of litigation. A review of benzene-induced AML suggests that, in developed countries, this entity should no longer merit serious consideration among workers in the modern petrochemical industry and related fields.
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MESH Headings
- Acute Disease
- Attitude of Health Personnel
- Benzene/adverse effects
- Benzene/therapeutic use
- Chromosome Aberrations/chemically induced
- Chromosome Inversion
- Chromosomes, Human, Pair 15
- Chromosomes, Human, Pair 16
- Chromosomes, Human, Pair 17
- Chromosomes, Human, Pair 21
- Chromosomes, Human, Pair 8
- Developed Countries
- Drug-Related Side Effects and Adverse Reactions
- Humans
- Leukemia, Myeloid/chemically induced
- Leukemia, Myeloid/diagnosis
- Leukemia, Myeloid/epidemiology
- Leukemia, Myeloid/etiology
- Leukemia, Myeloid/genetics
- Leukemia, Myeloid/pathology
- Occupational Diseases/chemically induced
- Occupational Diseases/epidemiology
- Occupational Exposure/adverse effects
- Occupational Exposure/analysis
- Petroleum/adverse effects
- Translocation, Genetic
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Affiliation(s)
- Ethan A Natelson
- Department of Medicine, Weill Medical College at the Methodist Hospital, Houston, Texas 77030, USA.
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Abstract
A large population of humans is exposed to benzene from various occupational and environmental sources. Benzene is an established human and animal carcinogen. Exposure to benzene has been associated with leukaemia in humans and several types of malignancies in animals. The exact mechanism of benzene-induced toxicity is poorly understood. It is believed that benzene exerts its adverse effects by metabolic activation to toxic metabolites. Certain benzene metabolites are genotoxic and mutagenic. This consolidated short-review is composed of human and animal studies to summarize the adverse effects of benzene with special reference to molecular mechanisms involved in benzene-induced toxicity.
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Affiliation(s)
- Haseeb Ahmad Khan
- Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia.
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McClendon AK, Osheroff N. DNA topoisomerase II, genotoxicity, and cancer. Mutat Res 2007; 623:83-97. [PMID: 17681352 PMCID: PMC2679583 DOI: 10.1016/j.mrfmmm.2007.06.009] [Citation(s) in RCA: 297] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 06/06/2007] [Accepted: 06/16/2007] [Indexed: 12/23/2022]
Abstract
Type II topoisomerases are ubiquitous enzymes that play essential roles in a number of fundamental DNA processes. They regulate DNA under- and overwinding, and resolve knots and tangles in the genetic material by passing an intact double helix through a transient double-stranded break that they generate in a separate segment of DNA. Because type II topoisomerases generate DNA strand breaks as a requisite intermediate in their catalytic cycle, they have the potential to fragment the genome every time they function. Thus, while these enzymes are essential to the survival of proliferating cells, they also have significant genotoxic effects. This latter aspect of type II topoisomerase has been exploited for the development of several classes of anticancer drugs that are widely employed for the clinical treatment of human malignancies. However, considerable evidence indicates that these enzymes also trigger specific leukemic chromosomal translocations. In light of the impact, both positive and negative, of type II topoisomerases on human cells, it is important to understand how these enzymes function and how their actions can destabilize the genome. This article discusses both aspects of human type II topoisomerases.
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Affiliation(s)
- A. Kathleen McClendon
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
| | - Neil Osheroff
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
- Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
- Corresponding author. Tel: +1 615 3224338; fax: +1 615 3431166, E-mail address: (N. Osheroff)
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29
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Zhang L, Rothman N, Li G, Guo W, Yang W, Hubbard AE, Hayes RB, Yin S, Lu W, Smith MT. Aberrations in chromosomes associated with lymphoma and therapy-related leukemia in benzene-exposed workers. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2007; 48:467-74. [PMID: 17584886 DOI: 10.1002/em.20306] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Epidemiological studies show that benzene exposure is associated with an increased incidence of leukemia and perhaps lymphoma. Chromosomal rearrangements are common in these hematopoietic diseases. Translocation t(14;18), the long-arm deletion of chromosome 6 [del(6q)], and trisomy 12 are frequently observed in lymphoma patients. Rearrangements of the MLL gene located on chromosome 11q23, such as t(4;11) and t(6;11), are common in therapy-related leukemias resulting from treatment with topoisomerase II inhibiting drugs. To examine numerical and structural changes in these chromosomes (2, 4, 6, 11, 12, 14, and 18), fluorescence in situ hybridization (FISH) was employed on metaphase spreads from workers exposed to benzene (n = 43) and matched controls (n = 44) from Shanghai, China. Aneuploidy (both monosomy and trisomy) of all seven chromosomes was increased by benzene exposure. Benzene also induced del(6q) in a dose-dependent manner (P(trend) = 0.0002). Interestingly, translocations between chromosomes 14 and 18, t(14;18), known to be associated with follicular non-Hodgkin lymphoma, were increased in the highly exposed workers (P < 0.001). On the other hand, translocations between chromosome 11 and other partner chromosomes that are found in therapy-induced leukemias were not increased. These data add weight to the notion that benzene can induce t(14;18) and del(6q) found in lymphoma, but do not support the idea that benzene induces t(4;11) or t(6;11). However, they do not rule out the possibility that other rearrangements of the MLL gene at chromosome 11q23 may be induced by benzene.
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Affiliation(s)
- Luoping Zhang
- School of Public Health, University of California, Berkeley, California, USA.
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30
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Bender RP, Ham AJL, Osheroff N. Quinone-induced enhancement of DNA cleavage by human topoisomerase IIalpha: adduction of cysteine residues 392 and 405. Biochemistry 2007; 46:2856-64. [PMID: 17298034 PMCID: PMC2896225 DOI: 10.1021/bi062017l] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Several quinone-based metabolites of drugs and environmental toxins are potent topoisomerase II poisons. These compounds act by adducting the protein and appear to increase levels of enzyme-DNA cleavage complexes by at least two potentially independent mechanisms. Treatment of topoisomerase IIalpha with quinones inhibits DNA religation and blocks the N-terminal gate of the protein by cross-linking its two protomer subunits. It is not known whether these two effects result from adduction of quinone to the same amino acid residue(s) in topoisomerase IIalpha or whether they are mediated by modification of separate residues. Therefore, this study identified amino acid residues in human topoisomerase IIalpha that are modified by quinones and determined their role in the actions of these compounds as topoisomerase II poisons. Four cysteine residues were identified by mass spectrometry as sites of quinone adduction: Cys170, Cys392, Cys405, and Cys455. Mutations (Cys --> Ala) were individually generated at each position. Only mutations at Cys392 or Cys405 reduced sensitivity ( approximately 50% resistance) to benzoquinone. Top2alphaC392A and top2alphaC405A displayed faster rates ( approximately 2-fold) of DNA religation than wild-type topoisomerase IIalpha in the presence of the quinone. In contrast, as determined by DNA binding, protein clamp closing, and protomer cross-linking experiments, mutations at Cys392 and Cys405 did not affect the ability of benzoquinone to block the N-terminal gate of topoisomerase IIalpha. These findings indicate that adduction of Cys392 and Cys405 is important for the actions of quinones against the enzyme and increases levels of cleavage complexes primarily by inhibiting DNA religation.
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Affiliation(s)
| | | | - Neil Osheroff
- To whom correspondence should be addressed. Tel: 615-322-4338. Fax: 615-343-1166.
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Anderson LM. Environmental genotoxicants/carcinogens and childhood cancer: Bridgeable gaps in scientific knowledge. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2006; 608:136-56. [PMID: 16829162 DOI: 10.1016/j.mrgentox.2006.02.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Accepted: 02/13/2006] [Indexed: 10/24/2022]
Abstract
Cancer in children is a major concern in many countries. An important question is whether these childhood cancers are caused by something, or are just tragic random events. Causation of at least some children's cancers is suggested by direct and indirect evidence, including epidemiological data, and animal studies that predict early life sensitivity of humans to carcinogenic effects. Candidate risk factors include genotoxic agents (chemicals and radiation), but also diet/nutrition, and infectious agents/immune responses. With regard to likelihood of risks posed by genotoxicants, there are pros and cons. The biological properties of fetuses and infants are consistent with sensitivity to preneoplastic genotoxic damage. Recent studies of genetic polymorphisms in carcinogen-metabolizing enzymes confirm a role for chemicals. On the other hand, in numerous epidemiological studies, associations between childhood cancers and exposure to genotoxicants, including tobacco smoke, have been weak and hard to reproduce. Possibly, sensitive genetic or ontogenetic subpopulations, and/or co-exposure situations need to be discovered to allow identification of susceptible individuals and their risk factors. Among the critical knowledge gaps needing to be bridged to aid in this effort include detailed tissue and cellular ontogeny of carcinogen metabolism and DNA repair enzymes, and associations of polymorphisms in DNA repair enzymes with childhood cancers. Perinatal bioassays in animals of specific environmental candidates, for example, benzene, could help guide epidemiology. Genetically engineered animal models could be useful for identification of chemical effects on specific genes. Investigations of interactions between factors may be key to understanding risk. Finally, fathers and newborn infants should receive more attention as especially sensitive targets.
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Affiliation(s)
- Lucy M Anderson
- Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, MD 21702, USA.
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