1
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Walker VE, Fennell TR, Walker DM, Bauer MJ, Upton PB, Douglas GR, Swenberg JA. Analysis of DNA Adducts and Mutagenic Potency and Specificity in Rats Exposed to Acrylonitrile. Chem Res Toxicol 2020; 33:1609-1622. [PMID: 32529823 DOI: 10.1021/acs.chemrestox.0c00153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Acrylonitrile (ACN), which is a widely used industrial chemical, induces cancers in multiple organs/tissues of rats by unresolved mechanisms. For this report, evidence for ACN-induced direct/indirect DNA damage and mutagenesis was investigated by assessing the ability of ACN, or its reactive metabolite, 2-cyanoethylene oxide (CEO), to bind to DNA in vitro, to form select DNA adducts [N7-(2'-oxoethyl)guanine, N2,3-ethenoguanine, 1,N6-ethenodeoxyadenosine, and 3,N4-ethenodeoxycytidine] in vitro and/or in vivo, and to perturb the frequency and spectra of mutations in the hypoxanthine-guanine phosphoribosyltransferase (Hprt) gene in rats exposed to ACN in drinking water. Adducts and frequencies and spectra of Hprt mutations were analyzed using published methods. Treatment of DNA from human TK6 lymphoblastoid cells with [2,3-14C]-CEO produced dose-dependent binding of 14C-CEO equivalents, and treatment of DNA from control rat brain/liver with CEO induced dose-related formation of N7-(2'-oxoethyl)guanine. No etheno-DNA adducts were detected in target tissues (brain and forestomach) or nontarget tissues (liver and spleen) in rats exposed to 0, 3, 10, 33, 100, or 300 ppm ACN for up to 105 days or to 0 or 500 ppm ACN for ∼15 months; whereas N7-(2'-oxoethyl)guanine was consistently measured at nonsignificant concentrations near the assay detection limit only in liver of animals exposed to 300 or 500 ppm ACN for ≥2 weeks. Significant dose-related increases in Hprt mutant frequencies occurred in T-lymphocytes from spleens of rats exposed to 33-500 ppm ACN for 4 weeks. Comparisons of "mutagenic potency estimates" for control rats versus rats exposed to 500 ppm ACN for 4 weeks to analogous data from rats/mice treated at a similar age with N-ethyl-N-nitrosourea or 1,3-butadiene suggest that ACN has relatively limited mutagenic effects in rats. Considerable overlap between the sites and types of mutations in ACN-exposed rats and butadiene-exposed rats/mice, but not controls, provides evidence that the carcinogenicity of these epoxide-forming chemicals involves corresponding mutagenic mechanisms.
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Affiliation(s)
- Vernon E Walker
- Chemical Industry Institute of Toxicology, Research Triangle Park, North Carolina 27709, United States.,Department of Pathology and Laboratory Medicine, University of Vermont, Burlington, Vermont 05405, United States.,The Burlington HC Research Group, Inc., Jericho, Vermont 05465, United States
| | - Timothy R Fennell
- Chemical Industry Institute of Toxicology, Research Triangle Park, North Carolina 27709, United States.,Center for Bioorganic Chemistry, RTI International, Research Triangle Park, North Carolina 27709, United States
| | - Dale M Walker
- The Burlington HC Research Group, Inc., Jericho, Vermont 05465, United States.,Experimental Pathology Laboratories, Sterling, Virginia 20167, United States
| | | | - Patricia B Upton
- Chemical Industry Institute of Toxicology, Research Triangle Park, North Carolina 27709, United States.,Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - George R Douglas
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada
| | - James A Swenberg
- Chemical Industry Institute of Toxicology, Research Triangle Park, North Carolina 27709, United States.,Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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2
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Andersen ME, Gentry PR, Swenberg JA, Mundt KA, White KW, Thompson C, Bus J, Sherman JH, Greim H, Bolt H, Marsh GM, Checkoway H, Coggon D, Clewell HJ. Considerations for refining the risk assessment process for formaldehyde: Results from an interdisciplinary workshop. Regul Toxicol Pharmacol 2019; 106:210-223. [PMID: 31059732 DOI: 10.1016/j.yrtph.2019.04.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 04/17/2019] [Accepted: 04/21/2019] [Indexed: 01/06/2023]
Abstract
Anticipating the need to evaluate and integrate scientific evidence to inform new risk assessments or to update existing risk assessments, the Formaldehyde Panel of the American Chemistry Council (ACC), in collaboration with the University of North Carolina, convened a workshop: "Understanding Potential Human Health Cancer Risk - From Data Integration to Risk Evaluation" in October 2017. Twenty-four (24) invited-experts participated with expertise in epidemiology, toxicology, science integration and risk evaluation. Including members of the organizing committee, there were 29 participants. The meeting included eleven presentations encompassing an introduction and three sessions: (1) "integrating the formaldehyde science on nasal/nasopharyngeal carcinogenicity and potential for causality"; (2) "integrating the formaldehyde science on lymphohematopoietic cancer and potential for causality; and, (3) "formaldehyde research-data suitable for risk assessment". Here we describe key points from the presentations on epidemiology, toxicology and mechanistic studies that should inform decisions about the potential carcinogenicity of formaldehyde in humans and the discussions about approaches for structuring an integrated, comprehensive risk assessment for formaldehyde. We also note challenges expected when attempting to reconcile divergent results observed from research conducted within and across different scientific disciplines - especially toxicology and epidemiology - and in integrating diverse, multi-disciplinary mechanistic evidence.
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Affiliation(s)
- Melvin E Andersen
- ScitoVation LLC, 100 Capitola Drive, Drive 106, Durham, NC, 27713, USA.
| | | | - James A Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Kenneth A Mundt
- Ramboll US Corporation, Amherst, MA (currently with Cardno Chemrisk, Boston, MA, USA
| | | | | | - James Bus
- Center for Toxicology and Mechanistic Biology, Exponent, Alexandria, VA, USA
| | | | | | - Hermann Bolt
- Leibniz Institute for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Gary M Marsh
- Department of Biostatistics, Center for Occupational Biostatistics and Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Harvey Checkoway
- University of California, San Diego, Department of Family Medicine and Public Health, USA
| | - David Coggon
- MRC Lifecourse Epidemiology Unit, University of Southampton, United Kingdom
| | - Harvey J Clewell
- Ramboll US Corporation, 6 Davis Drive, Suite 13, Research Triangle Park, NC, 27709, USA
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3
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Quist EM, Boorman GA, Cullen JM, Maronpot RR, Remick AK, Swenberg JA, Freshwater L, Hardisty JF. Reevaluation of Hepatocellular Neoplasms in CD-1 Mice from a 2-year Oral Carcinogenicity Study with Permethrin. Toxicol Pathol 2018; 47:11-17. [DOI: 10.1177/0192623318809304] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A 24-month oral carcinogenicity study of permethrin was conducted by feeding male and female CD-1 mice diets containing concentrations of 0, 20, 500, and 2,000 ppm of permethrin (males) or 0, 20, 2,500, and 5,000 ppm of permethrin (females). After approximately two years on study, surviving mice were sacrificed for the evaluation of chronic toxicity and/or carcinogenicity. An expert panel of pathologists was convened as a Pathology Working Group (PWG) to review coded liver histology sections from male and female mice and to classify all liver neoplasms according to current nomenclature and diagnostic criteria guidelines. The PWG results indicate that permethrin induced a significant dose-dependent increase in the incidence of hepatocellular neoplasms in treated female mice ( p < .01) as well as a nonstatistically significant increase in the incidence of hepatocellular tumors in treated male mice. Given the continuum of the diagnoses of adenoma and carcinoma, and the difficulty in distinguishing some of the lesions, it is appropriate to consider only the combined incidences of hepatocellular tumors (adenoma and/or carcinoma) for biological significance and risk assessment.
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Affiliation(s)
- Erin M. Quist
- Experimental Pathology Laboratories, Inc., Research Triangle Park, North Carolina, USA
| | | | - John M. Cullen
- North Carolina State University, Raleigh, North Carolina, USA
| | | | - Amera K. Remick
- Charles River Laboratories, Inc., Durham, North Carolina, USA
| | | | | | - Jerry F. Hardisty
- Experimental Pathology Laboratories, Inc., Research Triangle Park, North Carolina, USA
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4
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Liu CW, Tian X, Hartwell HJ, Leng J, Chi L, Lu K, Swenberg JA. Accurate Measurement of Formaldehyde-Induced DNA–Protein Cross-Links by High-Resolution Orbitrap Mass Spectrometry. Chem Res Toxicol 2018; 31:350-357. [DOI: 10.1021/acs.chemrestox.8b00040] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chih-Wei Liu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Xu Tian
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Hadley J. Hartwell
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jiapeng Leng
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Liang Chi
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Kun Lu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - James A. Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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5
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Hashimoto K, Sharma V, Sasanuma H, Tian X, Takata M, Takeda S, Swenberg JA, Nakamura J. Poor recognition of O6-isopropyl dG by MGMT triggers double strand break-mediated cell death and micronucleus induction in FANC-deficient cells. Oncotarget 2018; 7:59795-59808. [PMID: 27486975 PMCID: PMC5312349 DOI: 10.18632/oncotarget.10928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 07/18/2016] [Indexed: 12/03/2022] Open
Abstract
Isopropyl methanesulfonate (IPMS) is the most potent genotoxic compound among methanesulfonic acid esters. The genotoxic potential of alkyl sulfonate esters is believed to be due to their alkylating ability of the O6 position of guanine. Understanding the primary repair pathway activated in response to IPMS-induced DNA damage is important to profile the genotoxic potential of IPMS. In the present study, both chicken DT40 and human TK6 cell-based DNA damage response (DDR) assays revealed that dysfunction of the FANC pathway resulted in higher sensitivity to IPMS compared to EMS or MMS. O6-alkyl dG is primarily repaired by methyl guanine methyltransferase (MGMT), while isopropyl dG is less likely to be a substrate for MGMT. Comparison of the cytotoxic potential of IPMS and its isomer n-propyl methanesulfonate (nPMS) revealed that the isopropyl moiety avoids recognition by MGMT and leads to higher cytotoxicity. Next, the micronucleus (MN) assay showed that FANC deficiency increases the sensitivity of DT40 cells to MN induction by IPMS. Pretreatment with O6-benzyl guanine (OBG), an inhibitor of MGMT, increased the MN frequency in DT40 cells treated with nPMS, but not IPMS. Lastly, IPMS induced more double strand breaks in FANC-deficient cells compared to wild-type cells in a time-dependent manner. All together, these results suggest that IPMS-derived O6-isopropyl dG escapes recognition by MGMT, and the unrepaired DNA damage leads to double strand breaks, resulting in MN induction. FANC, therefore, plays a pivotal role in preventing MN induction and cell death caused by IPMS.
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Affiliation(s)
- Kiyohiro Hashimoto
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA.,Drug Safety Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa 251-8555, Japan
| | - Vyom Sharma
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | - Hiroyuki Sasanuma
- Department of Radiation Genetics, Kyoto University, Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Xu Tian
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | - Minoru Takata
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics, Kyoto University, Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | - Jun Nakamura
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
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6
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Sharma V, Collins LB, Chen TH, Herr N, Takeda S, Sun W, Swenberg JA, Nakamura J. Oxidative stress at low levels can induce clustered DNA lesions leading to NHEJ mediated mutations. Oncotarget 2018; 7:25377-90. [PMID: 27015367 PMCID: PMC5041911 DOI: 10.18632/oncotarget.8298] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 03/13/2016] [Indexed: 12/12/2022] Open
Abstract
DNA damage and mutations induced by oxidative stress are associated with various different human pathologies including cancer. The facts that most human tumors are characterized by large genome rearrangements and glutathione depletion in mice results in deletions in DNA suggest that reactive oxygen species (ROS) may cause gene and chromosome mutations through DNA double strand breaks (DSBs). However, the generation of DSBs at low levels of ROS is still controversial. In the present study, we show that H2O2 at biologically-relevant levels causes a marked increase in oxidative clustered DNA lesions (OCDLs) with a significant elevation of replication-independent DSBs. Although it is frequently reported that OCDLs are fingerprint of high-energy IR, our results indicate for the first time that H2O2, even at low levels, can also cause OCDLs leading to DSBs specifically in G1 cells. Furthermore, a reverse genetic approach revealed a significant contribution of the non-homologous end joining (NHEJ) pathway in H2O2-induced DNA repair & mutagenesis. This genomic instability induced by low levels of ROS may be involved in spontaneous mutagenesis and the etiology of a wide variety of human diseases like chronic inflammation-related disorders, carcinogenesis, neuro-degeneration and aging.
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Affiliation(s)
- Vyom Sharma
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
| | - Leonard B Collins
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
| | - Ting-Huei Chen
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Natalie Herr
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Wei Sun
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
| | - Jun Nakamura
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, Chapel Hill, NC 27599, USA
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7
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De La Rosa VY, Asfaha J, Fasullo M, Loguinov A, Li P, Moore LE, Rothman N, Nakamura J, Swenberg JA, Scelo G, Zhang L, Smith MT, Vulpe CD. Editor's Highlight: High-Throughput Functional Genomics Identifies Modulators of TCE Metabolite Genotoxicity and Candidate Susceptibility Genes. Toxicol Sci 2017; 160:111-120. [PMID: 28973557 PMCID: PMC5837773 DOI: 10.1093/toxsci/kfx159] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Trichloroethylene (TCE), an industrial chemical and environmental contaminant, is a human carcinogen. Reactive metabolites are implicated in renal carcinogenesis associated with TCE exposure, yet the toxicity mechanisms of these metabolites and their contribution to cancer and other adverse effects remain unclear. We employed an integrated functional genomics approach that combined functional profiling studies in yeast and avian DT40 cell models to provide new insights into the specific mechanisms contributing to toxicity associated with TCE metabolites. Genome-wide profiling studies in yeast identified the error-prone translesion synthesis (TLS) pathway as an import mechanism in response to TCE metabolites. The role of TLS DNA repair was further confirmed by functional profiling in DT40 avian cell lines, but also revealed that TLS and homologous recombination DNA repair likely play competing roles in cellular susceptibility to TCE metabolites in higher eukaryotes. These DNA repair pathways are highly conserved between yeast, DT40, and humans. We propose that in humans, mutagenic TLS is favored over homologous recombination repair in response to TCE metabolites. The results of these studies contribute to the body of evidence supporting a mutagenic mode of action for TCE-induced renal carcinogenesis mediated by reactive metabolites in humans. Our approach illustrates the potential for high-throughput in vitro functional profiling in yeast to elucidate toxicity pathways (molecular initiating events, key events) and candidate susceptibility genes for focused study.
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Affiliation(s)
- Vanessa Y. De La Rosa
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720
| | - Jonathan Asfaha
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720
| | - Michael Fasullo
- Colleges of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, Albany, New York 12205
| | - Alex Loguinov
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720
| | - Peng Li
- International Agency for Research on Cancer (IARC), Lyon, France
| | - Lee E. Moore
- Division of Cancer Epidemiology and Genetics, Department of Health and Human Services, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Nathaniel Rothman
- Division of Cancer Epidemiology and Genetics, Department of Health and Human Services, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Jun Nakamura
- Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
| | | | - Ghislaine Scelo
- International Agency for Research on Cancer (IARC), Lyon, France
| | - Luoping Zhang
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California 94720
| | - Martyn T. Smith
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California 94720
| | - Chris D. Vulpe
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720
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8
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Edrissi B, Taghizadeh K, Moeller BC, Yu R, Kracko D, Doyle-Eisele M, Swenberg JA, Dedon PC. N 6-Formyllysine as a Biomarker of Formaldehyde Exposure: Formation and Loss of N 6-Formyllysine in Nasal Epithelium in Long-Term, Low-Dose Inhalation Studies in Rats. Chem Res Toxicol 2017; 30:1572-1576. [PMID: 28692800 PMCID: PMC5807069 DOI: 10.1021/acs.chemrestox.7b00075] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Exposure to both endogenous and exogenous formaldehyde has been established to be carcinogenic, likely by virtue of forming nucleic acid and proteins adducts such as N6-formyllysine. To better assess N6-formyllysine as a biomarker of formaldehyde exposure, we studied accumulation of N6-formyllysine adducts in tissues of rats exposed by inhalation to 2 ppm [13C2H2]-formaldehyde for 7, 14, 21, and 28 days (6 h/day) and investigated adduct loss over a 7-day postexposure period using liquid chromatography-coupled tandem mass spectrometry. Our results showed formation of exogenous adducts in nasal epithelium and to some extent in trachea but not in distant tissues of lung, bone marrow, or white blood cells, with a 2-fold increase over endogenous N6-formyllysine over a 3-week exposure period. Postexposure analyses indicated a biexponential decay of N6-formyllysine in proteins extracted from different cellular compartments, with half-lives of ∼25 and ∼182 h for the fast and slow phases, respectively, in cytoplasmic proteins. These results parallel the behavior of DNA adducts and DNA-protein cross-links, with protein adducts cleared faster than DNA-protein cross-links, and point to the potential utility of N6-formyllysine protein adducts as biomarkers of formaldehyde.
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Affiliation(s)
- Bahar Edrissi
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Koli Taghizadeh
- Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Benjamin C. Moeller
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC, 27514, USA
- Lovelace Respiratory Research Institute, Albuquerque, NM, 87108, USA
| | - Rui Yu
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC, 27514, USA
| | - Dean Kracko
- Lovelace Respiratory Research Institute, Albuquerque, NM, 87108, USA
| | | | - James A. Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC, 27514, USA
| | - Peter C. Dedon
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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9
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Klaus V, Bastek H, Damme K, Collins LB, Frötschl R, Benda N, Lutter D, Ellinger-Ziegelbauer H, Swenberg JA, Dietrich DR, Stemmer K. Time-matched analysis of DNA adduct formation and early gene expression as predictive tool for renal carcinogenesis in methylazoxymethanol acetate treated Eker rats. Arch Toxicol 2017; 91:3427-3438. [PMID: 28349193 DOI: 10.1007/s00204-017-1953-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 03/01/2017] [Indexed: 11/28/2022]
Abstract
Genotoxic carcinogens pose great hazard to human health. Uncertainty of current risk assessment strategies and long latency periods between first carcinogen exposure and diagnosis of tumors have raised interest in predictive biomarkers. Initial DNA adduct formation is a necessary step for genotoxin induced carcinogenesis. However, as DNA adducts not always translate into tumorigenesis, their predictive value is limited. Here we hypothesize that the combined analysis of pro-mutagenic DNA adducts along with time-matched gene expression changes could serve as a superior prediction tool for genotoxic carcinogenesis. Eker rats, heterozygous for the tuberous sclerosis (Tsc2) tumor suppressor gene and thus highly susceptible towards genotoxic renal carcinogens, were continuously treated with the DNA alkylating carcinogen methylazoxymethanol acetate (MAMAc). Two weeks of MAMAc treatment resulted in a time-dependent increase of O6-methylguanine and N7-methylguanine adducts in the kidney cortex, which was however not reflected by significant expression changes of cyto-protective genes involved in DNA repair, cell cycle arrest or apoptosis. Instead, we found a transcriptional regulation of genes involved in the tumor-related MAPK, FoxO and TGF-beta pathways. Continuous MAMAc treatment for up to 6 months resulted in a mild but significant increase of cancerous lesions. In summary, the combined analysis of DNA adducts and early gene expression changes could serve as a suitable predictive tool for genotoxicant-induced carcinogenesis.
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Affiliation(s)
- Valentina Klaus
- Computational Discovery Research, Institute for Diabetes and Obesity, Helmholtz Diabetes Center & German Center for Diabetes Research (DZD), Helmholtz Zentrum München, Neuherberg, Germany
| | - Heinke Bastek
- Human and Environmental Toxicology, University of Konstanz, Konstanz, Germany
| | - Katja Damme
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Leonard B Collins
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Roland Frötschl
- Federal Institute for Drugs and Medical Devices, Bonn, Germany
| | - Norbert Benda
- Federal Institute for Drugs and Medical Devices, Bonn, Germany
| | - Dominik Lutter
- Computational Discovery Research, Institute for Diabetes and Obesity, Helmholtz Diabetes Center & German Center for Diabetes Research (DZD), Helmholtz Zentrum München, Neuherberg, Germany
| | | | - James A Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Daniel R Dietrich
- Human and Environmental Toxicology, University of Konstanz, Konstanz, Germany
| | - Kerstin Stemmer
- Metabolism and Cancer, Institute for Diabetes and Obesity, Helmholtz Diabetes Center & German Center for Diabetes Research (DZD), Helmholtz Zentrum München, Neuherberg, Germany.
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10
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Gao L, Mutlu E, Collins LB, Walker NJ, Hartwell HJ, Olson JR, Sun W, Gold A, Ball LM, Swenberg JA. DNA Product Formation in Female Sprague-Dawley Rats Following Polyhalogenated Aromatic Hydrocarbon (PHAH) Exposure. Chem Res Toxicol 2017; 30:794-803. [PMID: 28207250 PMCID: PMC5363288 DOI: 10.1021/acs.chemrestox.6b00368] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
![]()
DNA
oxidation damage has been regarded as one of the possible mechanisms
for the hepatic carcinogenesis of dioxin-like compounds (DLCs). In
this study, we evaluated the toxic equivalency factor (TEF) from the
standpoint of induced DNA oxidation products and their relationship
to toxicity and carcinogenicity. Nine DNA oxidation products were
analyzed in the liver of female Sprague–Dawley rats exposed
to 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD) alone or the tertiary
mixture of TCDD, 3,3′,4,4′,5-pentachlorobiphenyl (PCB
126), and 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) by gavage
for 14, 31, and 53 weeks (5 days/week) by LC–MS/MS: 8-oxo-7,8-dihydro-2′-deoxyguanosine
(8-oxo-dGuo); 1,N6-etheno-2′-deoxyadenosine
(1,N6-εdAdo); N2,3-ethenoguanine (N2,3-εG);
7-(2-oxoethly)guanine (7-OEG); 1,N2-etheno-2′-deoxyguanosine
(1,N2-εdGuo); malondialdehyde (M1dGuo); acrolein (AcrdGuo); crotonaldehyde (CrdGuo); and 4-hydroxynonenal
(HNEdGuo) derived 2′-deoxyguanosine adducts. Exposure to TCDD
(100 ng/kg/day) significantly induced 1,N6-εdAdo at 31 and 53 weeks, while no increase of 8-oxo-dGuo
was observed. Significant increases were observed for 8-oxo-dGuo and
1,N6-εdAdo at all time points following
exposure to the tertiary mixture (TEQ 100 ng/kg/day). Exposure to
TCDD for 53 weeks only significantly increased 1,N6-εdAdo, while increases of N2,3-εG and 7-OEG were only found in the highest dose
group (100 ng/kg/day). Exposure to the tertiary mixture for 53 weeks
had no effect on N2,3-εG in any
exposure group (TEQ 0, 22, 46, or 100 ng/kg/day), while significant
increases were observed for 1,N6-εdAdo
(all dose groups), 8-oxo-dGuo (46 and 100 ng/kg/day), and 7-OEG (100
ng/kg/day). While no significant increase was observed at 53 weeks
for 1,N2-εdGuo, M1dGuo,
AcrdGuo, or CrdGuo following exposure to TCDD (100 ng/kg/day), all
of them were significantly induced in animals exposed to the tertiary
mixture (TEQ 100 ng/kg/day). This oxidation DNA product data suggest
that the simple TEF methodology cannot be applied to evaluate the
diverse patterns of toxic effects induced by DLCs.
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Affiliation(s)
| | - Esra Mutlu
- National Toxicology Program, National Institute of Environmental Health Sciences, NIH, RTP , Durham, North Carolina 27709, United States
| | | | - Nigel J Walker
- National Toxicology Program, National Institute of Environmental Health Sciences, NIH, RTP , Durham, North Carolina 27709, United States
| | | | - James R Olson
- Department of Pharmacology and Toxicology, State University of New York at Buffalo , Buffalo, New York 14214, United States
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11
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Calderón-Garcidueñas L, Maronpot RR, Torres-Jardon R, Henríquez-Roldán C, Schoonhoven R, Acuña-Ayala H, Villarreal-Calderón A, Nakamura J, Fernando R, Reed W, Azzarelli B, Swenberg JA. DNA Damage in Nasal and Brain Tissues of Canines Exposed to Air Pollutants Is Associated with Evidence of Chronic Brain Inflammation and Neurodegeneration. Toxicol Pathol 2016; 31:524-38. [PMID: 14692621 DOI: 10.1080/01926230390226645] [Citation(s) in RCA: 228] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Acute, subchronic, or chronic exposures to particulate matter (PM) and pollutant gases affect people in urban areas and those exposed to fires, disasters, and wars. Respiratory tract inflammation, production of mediators of inflammation capable of reaching the brain, systemic circulation of PM, and disruption of the nasal respiratory and olfactory barriers are likely in these populations. DNA damage is crucial in aging and in age-associated diseases such as Alzheimer's disease. We evaluated apurinic/apyrimidinic (AP) sites in nasal and brain genomic DNA, and explored by immunohistochemistry the expression of nuclear factor NF κB p65, inducible nitric oxide synthase (iNOS), cyclo-oxygenase 2 (COX2), metallothionein I and II, apolipoprotein E, amyloid precursor protein (APP), and beta-amyloid1-42 in healthy dogs naturally exposed to urban pollution in Mexico City. Nickel (Ni) and vanadium (V) were measured by inductively coupled plasma mass spectrometry (ICP-MS). Forty mongrel dogs, ages 7 days—10 years were studied (14 controls from Tlaxcala and 26 exposed to urban pollution in South West Metropolitan Mexico City (SWMMC)). Nasal respiratory and olfactory epithelium were found to be early pollutant targets. Olfactory bulb and hippocampal AP sites were significantly higher in exposed than in control age matched animals. Ni and V were present in a gradient from olfactory mucosa > olfactory bulb > frontal cortex. Exposed dogs had (a) nuclear neuronal NF κB p65, (b) endothelial, glial and neuronal iNOS, (c) endothelial and glial COX2, (d) ApoE in neuronal, glial and vascular cells, and (e) APP and β amyloid1-42 in neurons, diffuse plaques (the earliest at age 11 months), and in subarachnoid blood vessels. Increased AP sites and the inflammatory and stress protein brain responses were early and significant in dogs exposed to urban pollution. Oil combustion PM-associated metals Ni and V were detected in the brain. There was an acceleration of Alzheimer's-type pathology in dogs chronically exposed to air pollutants. Respiratory tract inflammation and deteriorating olfactory and respiratory barriers may play a role in the observed neuropathology. These data suggest that Alzheimer's disease may be the sequela of air pollutant exposures and the resulting systemic inflammation.
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Affiliation(s)
- Lilian Calderón-Garcidueñas
- Environmental Pathology Program, University of North Carolina at Chapel Hill, North Carolina 27599-7310, USA.
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12
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Tian X, Patel K, Ridpath JR, Chen Y, Zhou YH, Neo D, Clement J, Takata M, Takeda S, Sale J, Wright FA, Swenberg JA, Nakamura J. Homologous Recombination and Translesion DNA Synthesis Play Critical Roles on Tolerating DNA Damage Caused by Trace Levels of Hexavalent Chromium. PLoS One 2016; 11:e0167503. [PMID: 27907204 PMCID: PMC5132242 DOI: 10.1371/journal.pone.0167503] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 11/15/2016] [Indexed: 12/17/2022] Open
Abstract
Contamination of potentially carcinogenic hexavalent chromium (Cr(VI)) in the drinking water is a major public health concern worldwide. However, little information is available regarding the biological effects of a nanomoler amount of Cr(VI). Here, we investigated the genotoxic effects of Cr(VI) at nanomoler levels and their repair pathways. We found that DNA damage response analyzed based on differential toxicity of isogenic cells deficient in various DNA repair proteins is observed after a three-day incubation with K2CrO4 in REV1-deficient DT40 cells at 19.2 μg/L or higher as well as in TK6 cells deficient in polymerase delta subunit 3 (POLD3) at 9.8 μg/L or higher. The genotoxicity of Cr(VI) decreased ~3000 times when the incubation time was reduced from three days to ten minutes. TK mutation rate also significantly decreased from 6 day to 1 day exposure to Cr(VI). The DNA damage response analysis suggest that DNA repair pathways, including the homologous recombination and REV1- and POLD3-mediated error-prone translesion synthesis pathways, are critical for the cells to tolerate to DNA damage caused by trace amount of Cr(VI).
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Affiliation(s)
- Xu Tian
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Keyur Patel
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - John R. Ridpath
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Youjun Chen
- Department of Neurology, UNC Neuroscience center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Yi-Hui Zhou
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina
| | - Dayna Neo
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jean Clement
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Minoru Takata
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Julian Sale
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Fred A. Wright
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina
- Department of Statistics, North Carolina State University, Raleigh, North Carolina
- * E-mail: (JN); (FW)
| | - James A. Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jun Nakamura
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- * E-mail: (JN); (FW)
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13
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Mutlu E, Gao L, Collins LB, Walker NJ, Hartwell HJ, Olson JR, Sun W, Gold A, Ball LM, Swenberg JA. Polychlorinated Biphenyls Induce Oxidative DNA Adducts in Female Sprague-Dawley Rats. Chem Res Toxicol 2016; 29:1335-1344. [PMID: 27436759 PMCID: PMC5020703 DOI: 10.1021/acs.chemrestox.6b00146] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Polychlorinated biphenyls (PCBs) are organic chemicals that were traditionally produced and widely used in industry as mixtures and are presently formed as byproducts of pigment and dye manufacturing. They are known to persist and bioaccumulate in the environment. Some have been shown to induce liver cancer in rodents. Although the mechanism of the toxicity of PCBs is unknown, it has been shown that they increase oxidative stress, including lipid peroxidation. We hypothesized that oxidative stress-induced DNA damage could be a contributor for PCB carcinogenesis and analyzed several DNA adducts in female Sprague-Dawley rats exposed to 3,3',4,4',5-pentachlorobiphenyl (PCB 126), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), and a binary mixture (PCB 126 + 153) for 14, 31, and 53 wks. Eight adducts were measured to profile oxidative DNA lesions, including 8-oxo-deoxyguanosine (8-oxo-dG), 1,N(6)-ethenodeoxyadenosine (1,N(6)-εdA), N(2),3-ethenoguanine (N(2),3-εG), 1,N(2)-ethenodeoxyguanosine (1,N(2)-εdG), as well as malondialdehyde (M1dG), acrolein (AcrdG), crotonaldehyde (CrdG), and 4-hydroxynonenal-derived dG adducts (HNEdG) by LC-MS/MS analysis. Statistically significant increases were observed for 8-oxo-dG and 1,N(6)-εdA concentrations in hepatic DNA of female rats exposed to the binary mixture (1000 ng/kg/day + 1000 μg/kg/day) but not in rats exposed to PCB 126 (1000 ng/kg/day) or PCB 153 (1000 μg/kg/day) for 14 and 31 wks. However, exposure to PCB 126 (1000 ng/kg/day) for 53 wks significantly increased 8-oxo-dG, 1,N(6)-εdA, AcrdG, and M1dG. Exposure to PCB 153 (1000 μg/kg/day) for 53 wks increased 8-oxo-dG, and 1,N(6)-εdA. Exposure to the binary mixture for 53 wks increased 8-oxo-dG, 1,N(6)-εdA, AcrdG, 1,N(2)-εdG, and N(2),3-εG significantly above control groups. Increased hepatic oxidative DNA adducts following exposure to PCB 126, PCB 153, or the binary mixture shows that an increase in DNA damage may play an important role in hepatic toxicity and carcinogenesis in female Sprague-Dawley rats.
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Affiliation(s)
- Esra Mutlu
- National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, United States
| | - Lina Gao
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Leonard B. Collins
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Nigel J. Walker
- National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, United States
| | - Hadley J. Hartwell
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - James R. Olson
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, New York 14214, United States
| | - Wei Sun
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Avram Gold
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Louise M. Ball
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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14
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Calderón-Garcidueñas L, Reed W, Maronpot RR, Henríquez-Roldán C, Delgado-Chavez R, Calderón-Garcidueñas A, Dragustinovis I, Franco-Lira M, Aragón-Flores M, Solt AC, Altenburg M, Torres-Jardón R, Swenberg JA. Brain Inflammation and Alzheimer's-Like Pathology in Individuals Exposed to Severe Air Pollution. Toxicol Pathol 2016; 32:650-8. [PMID: 15513908 DOI: 10.1080/01926230490520232] [Citation(s) in RCA: 351] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Air pollution is a complex mixture of gases (e.g., ozone), particulate matter, and organic compounds present in outdoor and indoor air. Dogs exposed to severe air pollution exhibit chronic inflammation and acceleration of Alzheimer's-like pathology, suggesting that the brain is adversely affected by pollutants. We investigated whether residency in cities with high levels of air pollution is associated with human brain inflammation. Expression of cyclooxygenase-2 (COX2), an inflammatory mediator, and accumulation of the 42-amino acid form of β-amyloid (A β42), a cause of neuronal dysfunction, were measured in autopsy brain tissues of cognitively and neurologically intact lifelong residents of cities having low (n:9) or high (n:10) levels of air pollution. Genomic DNA apurinic/apyrimidinic sites, nuclear factor- κB activation and apolipoprotein E genotype were also evaluated. Residents of cities with severe air pollution had significantly higher COX2 expression in frontal cortex and hippocampus and greater neuronal and astrocytic accumulation of A β42 compared to residents in low air pollution cities. Increased COX2 expression and A β42 accumulation were also observed in the olfactory bulb. These findings suggest that exposure to severe airpollution is associated with brain inflammation and A β 42 accumulation, two causes of neuronal dysfunction that precede the appearance of neuritic plaques and neurofibrillary tangles, hallmarks of Alzheimer's disease.
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15
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Wu TP, Wang T, Seetin MG, Lai Y, Zhu S, Lin K, Liu Y, Byrum SD, Mackintosh SG, Zhong M, Tackett A, Wang G, Hon LS, Fang G, Swenberg JA, Xiao AZ. DNA methylation on N(6)-adenine in mammalian embryonic stem cells. Nature 2016; 532:329-33. [PMID: 27027282 DOI: 10.1038/nature17640] [Citation(s) in RCA: 426] [Impact Index Per Article: 53.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 03/07/2016] [Indexed: 12/29/2022]
Abstract
It has been widely accepted that 5-methylcytosine is the only form of DNA methylation in mammalian genomes. Here we identify N(6)-methyladenine as another form of DNA modification in mouse embryonic stem cells. Alkbh1 encodes a demethylase for N(6)-methyladenine. An increase of N(6)-methyladenine levels in Alkbh1-deficient cells leads to transcriptional silencing. N(6)-methyladenine deposition is inversely correlated with the evolutionary age of LINE-1 transposons; its deposition is strongly enriched at young (<1.5 million years old) but not old (>6 million years old) L1 elements. The deposition of N(6)-methyladenine correlates with epigenetic silencing of such LINE-1 transposons, together with their neighbouring enhancers and genes, thereby resisting the gene activation signals during embryonic stem cell differentiation. As young full-length LINE-1 transposons are strongly enriched on the X chromosome, genes located on the X chromosome are also silenced. Thus, N(6)-methyladenine developed a new role in epigenetic silencing in mammalian evolution distinct from its role in gene activation in other organisms. Our results demonstrate that N(6)-methyladenine constitutes a crucial component of the epigenetic regulation repertoire in mammalian genomes.
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Affiliation(s)
- Tao P Wu
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Tao Wang
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Matthew G Seetin
- Pacific Biosciences, 1380 Willow Road, Menlo Park, California 94025, USA
| | - Yongquan Lai
- Environmental Sciences &Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Shijia Zhu
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Kaixuan Lin
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Yifei Liu
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Stephanie D Byrum
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Samuel G Mackintosh
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Mei Zhong
- Yale Stem Cell Center and Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Alan Tackett
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Guilin Wang
- Department of Molecular Biophysics &Biochemistry, Yale Center for Genome Analysis, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Lawrence S Hon
- Pacific Biosciences, 1380 Willow Road, Menlo Park, California 94025, USA
| | - Gang Fang
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - James A Swenberg
- Environmental Sciences &Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Andrew Z Xiao
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, Connecticut 06520, USA
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16
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Lai Y, Yu R, Hartwell HJ, Moeller BC, Bodnar WM, Swenberg JA. Measurement of Endogenous versus Exogenous Formaldehyde-Induced DNA-Protein Crosslinks in Animal Tissues by Stable Isotope Labeling and Ultrasensitive Mass Spectrometry. Cancer Res 2016; 76:2652-61. [PMID: 26984759 DOI: 10.1158/0008-5472.can-15-2527] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 02/14/2016] [Indexed: 12/24/2022]
Abstract
DNA-protein crosslinks (DPC) arise from a wide range of endogenous and exogenous chemicals, such as chemotherapeutic drugs and formaldehyde. Importantly, recent identification of aldehydes as endogenous genotoxins in Fanconi anemia has provided new insight into disease causation. Because of their bulky nature, DPCs pose severe threats to genome stability, but previous methods to measure formaldehyde-induced DPCs were incapable of discriminating between endogenous and exogenous sources of chemical. In this study, we developed methods that provide accurate and distinct measurements of both exogenous and endogenous DPCs in a structurally specific manner. We exposed experimental animals to stable isotope-labeled formaldehyde ([(13)CD2]-formaldehyde) by inhalation and performed ultrasensitive mass spectrometry to measure endogenous (unlabeled) and exogenous ((13)CD2-labeled) DPCs. We found that exogenous DPCs readily accumulated in nasal respiratory tissues but were absent in tissues distant to the site of contact. This observation, together with the finding that endogenous formaldehyde-induced DPCs were present in all tissues examined, suggests that endogenous DPCs may be responsible for increased risks of bone marrow toxicity and leukemia. Furthermore, the slow rate of DPC repair provided evidence for the persistence of DPCs. In conclusion, our method for measuring endogenous and exogenous DPCs presents a new perspective for the potential health risks inflicted by endogenous formaldehyde and may inform improved disease prevention and treatment strategies. Cancer Res; 76(9); 2652-61. ©2016 AACR.
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Affiliation(s)
- Yongquan Lai
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Rui Yu
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Hadley J Hartwell
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | | | - Wanda M Bodnar
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
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17
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Starr TB, Swenberg JA. The bottom-up approach to bounding potential low-dose cancer risks from formaldehyde: An update. Regul Toxicol Pharmacol 2016; 77:167-74. [PMID: 26851508 DOI: 10.1016/j.yrtph.2016.01.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 01/28/2016] [Accepted: 01/29/2016] [Indexed: 10/22/2022]
Abstract
In 2013, we proposed a novel bottom-up approach to bounding low-dose cancer risks that may result from small exogenous exposures to chemicals that are always present in the body as a result of normal biological processes. The approach utilizes the background cancer risk and the background (endogenous) concentration of a cancer-related exposure biomarker in specific target tissues. After allowing for statistical uncertainty in these two parameters, the ratio of the background risk to background exposure provides a conservative slope factor estimate that can be utilized to bound the added risk that may be associated with incremental exogenous exposures. Our original bottom-up estimates were markedly smaller than those obtained previously by the US Environmental Protection Agency (USEPA) with a conventional top-down approach to modeling nasopharyngeal cancer and leukemia mortality data from a US worker cohort. Herein we provide updated bottom-up estimates of risk for these two cancers that are smaller still, and rely upon more robust estimates of endogenous and exogenous formaldehyde-DNA adducts in monkeys and a more robust estimate of the DNA adduct elimination half-life in rats, both obtained very recently. We also re-examine the worker mortality data used by USEPA in developing its estimate of human leukemia incidence from lifetime exposure to 1 ppm airborne formaldehyde. Finally, we compare a new bottom-up slope estimate of the risk of rat nasal cancer with conventional top-down estimates obtained with empirical dose-response modeling of rat nasal cancer bioassay data.
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Affiliation(s)
- Thomas B Starr
- TBS Associates, 7500 Rainwater Road, Raleigh, NC 27615, USA; Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, 166 Rosenau Hall, CB #7431, Chapel Hill, NC 27599-7431, USA.
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, 166 Rosenau Hall, CB #7431, Chapel Hill, NC 27599-7431, USA.
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18
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Pontel LB, Rosado IV, Burgos-Barragan G, Garaycoechea JI, Yu R, Arends MJ, Chandrasekaran G, Broecker V, Wei W, Liu L, Swenberg JA, Crossan GP, Patel KJ. Endogenous Formaldehyde Is a Hematopoietic Stem Cell Genotoxin and Metabolic Carcinogen. Mol Cell 2015; 60:177-88. [PMID: 26412304 PMCID: PMC4595711 DOI: 10.1016/j.molcel.2015.08.020] [Citation(s) in RCA: 249] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 07/10/2015] [Accepted: 08/21/2015] [Indexed: 12/18/2022]
Abstract
Endogenous formaldehyde is produced by numerous biochemical pathways fundamental to life, and it can crosslink both DNA and proteins. However, the consequences of its accumulation are unclear. Here we show that endogenous formaldehyde is removed by the enzyme alcohol dehydrogenase 5 (ADH5/GSNOR), and Adh5(-/-) mice therefore accumulate formaldehyde adducts in DNA. The repair of this damage is mediated by FANCD2, a DNA crosslink repair protein. Adh5(-/-)Fancd2(-/-) mice reveal an essential requirement for these protection mechanisms in hematopoietic stem cells (HSCs), leading to their depletion and precipitating bone marrow failure. More widespread formaldehyde-induced DNA damage also causes karyomegaly and dysfunction of hepatocytes and nephrons. Bone marrow transplantation not only rescued hematopoiesis but, surprisingly, also preserved nephron function. Nevertheless, all of these animals eventually developed fatal malignancies. Formaldehyde is therefore an important source of endogenous DNA damage that is counteracted in mammals by a conserved protection mechanism.
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Affiliation(s)
- Lucas B Pontel
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Ivan V Rosado
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK; Instituto de Biomedicina de Sevilla (IBiS) Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain
| | | | - Juan I Garaycoechea
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Rui Yu
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Mark J Arends
- University of Edinburgh Division of Pathology, Edinburgh Cancer Research Centre, Institute of Genetics & Molecular Medicine, Western General Hospital, Crewe Road South, Edinburgh EH4 2XR, UK
| | | | - Verena Broecker
- Department of Histopathology, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Wei Wei
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Limin Liu
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Gerry P Crossan
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Ketan J Patel
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK; Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 2QQ, UK.
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19
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Leng S, Wu G, Collins LB, Thomas CL, Tellez CS, Jauregui AR, Picchi MA, Zhang X, Juri DE, Desai D, Amin SG, Crowell RE, Stidley CA, Liu Y, Swenberg JA, Lin Y, Wathelet MG, Gilliland FD, Belinsky SA. Implication of a Chromosome 15q15.2 Locus in Regulating UBR1 and Predisposing Smokers to MGMT Methylation in Lung. Cancer Res 2015; 75:3108-17. [PMID: 26183928 DOI: 10.1158/0008-5472.can-15-0243] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 05/22/2015] [Indexed: 11/16/2022]
Abstract
O(6)-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that protects cells from carcinogenic effects of alkylating agents; however, MGMT is silenced by promoter hypermethylation during carcinogenesis. A single-nucleotide polymorphism (SNP) in an enhancer in the MGMT promoter was previously identified to be highly significantly associated with risk for MGMT methylation in lung cancer and sputum from smokers. To further genetic investigations, a genome-wide association and replication study was conducted in two smoker cohorts to identify novel loci for MGMT methylation in sputum that were independent of the MGMT enhancer polymorphism. Two novel trans-acting loci (15q15.2 and 17q24.3) that were identified acted together with the enhancer SNP to empower risk prediction for MGMT methylation. We found that the predisposition to MGMT methylation arising from the 15q15.2 locus involved regulation of the ubiquitin protein ligase E3 component UBR1. UBR1 attenuation reduced turnover of MGMT protein and increased repair of O6-methylguanine in nitrosomethylurea-treated human bronchial epithelial cells, while also reducing MGMT promoter activity and abolishing MGMT induction. Overall, our results substantiate reduced gene transcription as a major mechanism for predisposition to MGMT methylation in the lungs of smokers, and support the importance of UBR1 in regulating MGMT homeostasis and DNA repair of alkylated DNA adducts in cells.
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Affiliation(s)
- Shuguang Leng
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Guodong Wu
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Leonard B Collins
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Cynthia L Thomas
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Carmen S Tellez
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Andrew R Jauregui
- Lung Fibrosis Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Maria A Picchi
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Xiequn Zhang
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Daniel E Juri
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Dhimant Desai
- Department of Pharmacology, Penn State College of Medicine, Hershey, Pennsylvania
| | - Shantu G Amin
- Department of Pharmacology, Penn State College of Medicine, Hershey, Pennsylvania
| | - Richard E Crowell
- Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico
| | - Christine A Stidley
- Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico
| | - Yushi Liu
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Yong Lin
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Marc G Wathelet
- Lung Fibrosis Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Frank D Gilliland
- Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Steven A Belinsky
- Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico.
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20
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Yu R, Lai Y, Hartwell HJ, Moeller BC, Doyle-Eisele M, Kracko D, Bodnar WM, Starr TB, Swenberg JA. Formation, Accumulation, and Hydrolysis of Endogenous and Exogenous Formaldehyde-Induced DNA Damage. Toxicol Sci 2015; 146:170-82. [PMID: 25904104 PMCID: PMC4476463 DOI: 10.1093/toxsci/kfv079] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Formaldehyde is not only a widely used chemical with well-known carcinogenicity but is also a normal metabolite of living cells. It thus poses unique challenges for understanding risks associated with exposure. N(2-)hydroxymethyl-dG (N(2)-HOMe-dG) is the main formaldehyde-induced DNA mono-adduct, which together with DNA-protein crosslinks (DPCs) and toxicity-induced cell proliferation, play important roles in a mutagenic mode of action for cancer. In this study, N(2)-HOMe-dG was shown to be an excellent biomarker for direct adduction of formaldehyde to DNA and the hydrolysis of DPCs. The use of inhaled [(13)CD2]-formaldehyde exposures of rats and primates coupled with ultrasensitive nano ultra performance liquid chromatography-tandem mass spectrometry permitted accurate determinations of endogenous and exogenous formaldehyde DNA damage. The results show that inhaled formaldehyde only reached rat and monkey noses, but not tissues distant to the site of initial contact. The amounts of exogenous adducts were remarkably lower than those of endogenous adducts in exposed nasal epithelium. Moreover, exogenous adducts accumulated in rat nasal epithelium over the 28-days exposure to reach steady-state concentrations, followed by elimination with a half-life (t1/2) of 7.1 days. Additionally, we examined artifact formation during DNA preparation to ensure the accuracy of nonlabeled N(2)-HOMe-dG measurements. These novel findings provide critical new data for understanding major issues identified by the National Research Council Review of the 2010 Environmental Protection Agency's Draft Integrated Risk Information System Formaldehyde Risk Assessment. They support a data-driven need for reflection on whether risks have been overestimated for inhaled formaldehyde, whereas underappreciating endogenous formaldehyde as the primary source of exposure that results in bone marrow toxicity and leukemia in susceptible humans and rodents deficient in DNA repair.
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Affiliation(s)
- Rui Yu
- *Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, North Carolina 27599
| | - Yongquan Lai
- *Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, North Carolina 27599
| | - Hadley J Hartwell
- *Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, North Carolina 27599
| | - Benjamin C Moeller
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87108; and
| | | | - Dean Kracko
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87108; and
| | - Wanda M Bodnar
- *Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, North Carolina 27599
| | - Thomas B Starr
- *Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, North Carolina 27599, TBS Associates, 7500 Rainwater Road, Raleigh, North Carolina 27615
| | - James A Swenberg
- *Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, North Carolina 27599,
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21
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Hashimoto K, Takeda S, Swenberg JA, Nakamura J. Incorporation of metabolic activation potentiates cyclophosphamide-induced DNA damage response in isogenic DT40 mutant cells. Mutagenesis 2015; 30:821-8. [PMID: 26085549 DOI: 10.1093/mutage/gev042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Elucidating the DNA repair pathways that are activated in the presence of genotoxic agents is critical to understand their modes of action. Although the DT40 cell-based DNA damage response (DDR) assay provides rapid and sensitive results, the assay cannot be used on genotoxic compounds that require metabolic activation to be reactive. Here, we applied the metabolic activation system to a DDR and micronucleus (MN) assays in DT40 cells. Cyclophosphamide (CP), a well-known cross-linking agent requiring metabolic activation, was preincubated with liver S9 fractions. When DT40 cells and mutant cells were exposed to the preactivated CP, CP caused increased cytotoxicity in FANC-, RAD9-, REV3- and RAD18-mutant cells compared to isogenic wild-type cells. We then performed a MN assay on DT40 cells treated with preactivated CP. An increase in the MN was observed in REV3- and FANC-mutant cells at lower concentrations of activated CP than in the parental DT40 cells. These results demonstrated that the incorporation of metabolic preactivation system using S9 fractions significantly potentiates DDR caused by CP in DT40 cells and their mutants. In addition, our data suggest that the metabolic preactivation system for DDR and MN assays has a potential to increase the relevance of this assay to screening various compounds for potential genotoxicity.
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Affiliation(s)
- Kiyohiro Hashimoto
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA, Drug Safety Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jun Nakamura
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA,
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22
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Swenberg JA, Richardson FC, Tyeryar L, Deal F, Boucheron J. The molecular dosimetry of DNA adducts formed by continuous exposure of rats to alkylating hepatocarcinogens. Prog Exp Tumor Res 2015; 31:42-51. [PMID: 3562859 DOI: 10.1159/000413902] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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23
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Swenberg JA, Koestner A. Histochemical studies on selected enzymes of experimental neuroectodermal tumors. Prog Exp Tumor Res 2015; 17:328-45. [PMID: 4343203 DOI: 10.1159/000393681] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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24
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Koestner A, Swenberg JA, Wechsler W. Experimental tumors of the nervous system induced by resorptive N-nitrosourea compounds. Prog Exp Tumor Res 2015; 17:9-30. [PMID: 5082337 DOI: 10.1159/000393664] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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25
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26
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Tian X, Patel K, Ridpath JR, Swenberg JA, Nakamura J. Abstract 5363: Genotoxicity of trace level of hexavalent chromium existing in city water. Carcinogenesis 2014. [DOI: 10.1158/1538-7445.am2014-5363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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27
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Donohoe DR, Holley D, Collins LB, Montgomery SA, Whitmore AC, Hillhouse A, Curry KP, Renner SW, Greenwalt A, Ryan EP, Godfrey V, Heise MT, Threadgill DS, Han A, Swenberg JA, Threadgill DW, Bultman SJ. A gnotobiotic mouse model demonstrates that dietary fiber protects against colorectal tumorigenesis in a microbiota- and butyrate-dependent manner. Cancer Discov 2014; 4:1387-97. [PMID: 25266735 DOI: 10.1158/2159-8290.cd-14-0501] [Citation(s) in RCA: 286] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
UNLABELLED Whether dietary fiber protects against colorectal cancer is controversial because of conflicting results from human epidemiologic studies. However, these studies and mouse models of colorectal cancer have not controlled the composition of gut microbiota, which ferment fiber into short-chain fatty acids such as butyrate. Butyrate is noteworthy because it has energetic and epigenetic functions in colonocytes and tumor-suppressive properties in colorectal cancer cell lines. We used gnotobiotic mouse models colonized with wild-type or mutant strains of a butyrate-producing bacterium to demonstrate that fiber does have a potent tumor-suppressive effect but in a microbiota- and butyrate-dependent manner. Furthermore, due to the Warburg effect, butyrate was metabolized less in tumors where it accumulated and functioned as a histone deacetylase (HDAC) inhibitor to stimulate histone acetylation and affect apoptosis and cell proliferation. To support the relevance of this mechanism in human cancer, we demonstrate that butyrate and histone-acetylation levels are elevated in colorectal adenocarcinomas compared with normal colonic tissues. SIGNIFICANCE These results, which link diet and microbiota to a tumor-suppressive metabolite, provide insight into conflicting epidemiologic findings and suggest that probiotic/prebiotic strategies can modulate an endogenous HDAC inhibitor for anticancer chemoprevention without the adverse effects associated with synthetic HDAC inhibitors used in chemotherapy.
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Affiliation(s)
- Dallas R Donohoe
- Department of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina
| | - Darcy Holley
- Department of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina
| | - Leonard B Collins
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
| | - Stephanie A Montgomery
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Alan C Whitmore
- Department of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina. Carolina Vaccine Institute, University of North Carolina, Chapel Hill, North Carolina
| | - Andrew Hillhouse
- Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas
| | - Kaitlin P Curry
- Department of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina
| | - Sarah W Renner
- Department of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina
| | - Alicia Greenwalt
- Department of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina
| | - Elizabeth P Ryan
- Department of Environmental and Radiological Health, Colorado State University, Fort Collins, Colorado
| | - Virginia Godfrey
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina
| | - Mark T Heise
- Department of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina. Carolina Vaccine Institute, University of North Carolina, Chapel Hill, North Carolina
| | - Deborah S Threadgill
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas
| | - Anna Han
- Department of Nutrition, University of Tennessee, Knoxville, Tennessee
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
| | - David W Threadgill
- Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas. Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas
| | - Scott J Bultman
- Department of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina.
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28
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Shibutani T, Ito S, Toda M, Kanao R, Collins LB, Shibata M, Urabe M, Koseki H, Masuda Y, Swenberg JA, Masutani C, Hanaoka F, Iwai S, Kuraoka I. Guanine- 5-carboxylcytosine base pairs mimic mismatches during DNA replication. Sci Rep 2014; 4:5220. [PMID: 24910358 PMCID: PMC4048885 DOI: 10.1038/srep05220] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 05/19/2014] [Indexed: 11/09/2022] Open
Abstract
The genetic information encoded in genomes must be faithfully replicated and transmitted to daughter cells. The recent discovery of consecutive DNA conversions by TET family proteins of 5-methylcytosine into 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine (5caC) suggests these modified cytosines act as DNA lesions, which could threaten genome integrity. Here, we have shown that although 5caC pairs with guanine during DNA replication in vitro, G·5caC pairs stimulated DNA polymerase exonuclease activity and were recognized by the mismatch repair (MMR) proteins. Knockdown of thymine DNA glycosylase increased 5caC in genome, affected cell proliferation via MMR, indicating MMR is a novel reader for 5caC. These results suggest the epigenetic modification products of 5caC behave as DNA lesions.
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Affiliation(s)
- Toshihiro Shibutani
- Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 Japan
| | - Shinsuke Ito
- Laboratory for Developmental Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Mariko Toda
- Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 Japan
| | - Rie Kanao
- Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Leonard B Collins
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Marika Shibata
- Laboratory for Developmental Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Miho Urabe
- Laboratory for Developmental Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Haruhiko Koseki
- Laboratory for Developmental Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Yuji Masuda
- 1] Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan [2] Department of Toxicogenomics, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Chikahide Masutani
- Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Fumio Hanaoka
- Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
| | - Shigenori Iwai
- Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 Japan
| | - Isao Kuraoka
- Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 Japan
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Sharma V, Collins LB, Clement JM, Zhang Z, Nakamura J, Swenberg JA. Molecular dosimetry of endogenous and exogenous O(6)-methyl-dG and N7-methyl-G adducts following low dose [D3]-methylnitrosourea exposures in cultured human cells. Chem Res Toxicol 2014; 27:480-2. [PMID: 24628573 PMCID: PMC3998766 DOI: 10.1021/tx5000602] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
For DNA-reactive chemicals, a low dose linear assessment of cancer risk is the science policy default. In the present study, we quantitated the endogenous and exogenous N7-methyl-G and O(6)-methyl-dG adducts in human lymphoblastoid cells exposed to low dose [D3]-methylnitrosourea. Endogenous amounts of both adducts remained nearly constant, while the exogenous adducts showed linear dose-responses. The data show that O(6)-methyl-dG adducts ≥1.8/10(8) dG correlated with published studies that demonstrated significant increases of mutations under these conditions. The combined results do not support linear extrapolations to zero when data are available for science-based regulations.
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Affiliation(s)
- Vyom Sharma
- Department of Environmental Sciences and Engineering, University of North Carolina , Campus Box 7431, Chapel Hill, North Carolina 27599-7431, United States
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30
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Lu K, Abo RP, Schlieper KA, Graffam ME, Levine S, Wishnok JS, Swenberg JA, Tannenbaum SR, Fox JG. Arsenic exposure perturbs the gut microbiome and its metabolic profile in mice: an integrated metagenomics and metabolomics analysis. Environ Health Perspect 2014; 122:284-91. [PMID: 24413286 PMCID: PMC3948040 DOI: 10.1289/ehp.1307429] [Citation(s) in RCA: 372] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 01/09/2014] [Indexed: 05/18/2023]
Abstract
BACKGROUND The human intestine is host to an enormously complex, diverse, and vast microbial community-the gut microbiota. The gut microbiome plays a profound role in metabolic processing, energy production, immune and cognitive development, epithelial homeostasis, and so forth. However, the composition and diversity of the gut microbiome can be readily affected by external factors, which raises the possibility that exposure to toxic environmental chemicals leads to gut microbiome alteration, or dysbiosis. Arsenic exposure affects large human populations worldwide and has been linked to a number of diseases, including cancer, diabetes, and cardiovascular disorders. OBJECTIVES We investigated the impact of arsenic exposure on the gut microbiome composition and its metabolic profiles. METHODS We used an integrated approach combining 16S rRNA gene sequencing and mass spectrometry-based metabolomics profiling to examine the functional impact of arsenic exposure on the gut microbiome. RESULTS 16S rRNA gene sequencing revealed that arsenic significantly perturbed the gut microbiome composition in C57BL/6 mice after exposure to 10 ppm arsenic for 4 weeks in drinking water. Moreover, metabolomics profiling revealed a concurrent effect, with a number of gut microflora-related metabolites being perturbed in multiple biological matrices. CONCLUSIONS Arsenic exposure not only alters the gut microbiome community at the abundance level but also substantially disturbs its metabolic profiles at the function level. These findings may provide novel insights regarding perturbations of the gut microbiome and its functions as a potential new mechanism by which arsenic exposure leads to or exacerbates human diseases. CITATION Lu K, Abo RP, Schlieper KA, Graffam ME, Levine S, Wishnok JS, Swenberg JA, Tannenbaum SR, Fox JG. 2014. Arsenic exposure perturbs the gut microbiome and its metabolic profile in mice: an integrated metagenomics and metabolomics analysis. Environ Health Perspect 122:284-291; http://dx.doi.org/10.1289/ehp.1307429.
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Affiliation(s)
- Kun Lu
- Department of Biological Engineering
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31
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Kotapati S, Sangaraju D, Esades A, Hallberg L, Walker VE, Swenberg JA, Tretyakova NY. Bis-butanediol-mercapturic acid (bis-BDMA) as a urinary biomarker of metabolic activation of butadiene to its ultimate carcinogenic species. Carcinogenesis 2014; 35:1371-8. [PMID: 24531806 DOI: 10.1093/carcin/bgu047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Human carcinogen 1,3-butadiene (BD) undergoes metabolic activation to 3,4-epoxy-1-butene (EB), hydroxymethylvinyl ketone (HMVK), 3,4-epoxy-1,2-butanediol (EBD) and 1,2,3,4-diepoxybutane (DEB). Among these, DEB is by far the most genotoxic metabolite and is considered the ultimate carcinogenic species of BD. We have shown previously that BD-exposed laboratory mice form 8- to 10-fold more DEB-DNA adducts than rats exposed at the same conditions, which may be responsible for the enhanced sensitivity of mice to BD-mediated cancer. In the present study, we have identified 1,4-bis-(N-acetyl-L-cystein-S-yl)butane-2,3-diol (bis-BDMA) as a novel DEB-specific urinary biomarker. Isotope dilution high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry was employed to quantify bis-BDMA and three other BD-mercapturic acids, 2-(N-acetyl-L-cystein-S-yl)-1-hydroxybut-3-ene/1-(N-acetyl-L-cystein-S-yl)-2-hydroxy-but-3-ene (MHBMA, from EB), 4-(N-acetyl-L-cystein-S-yl)-1,2-dihydroxybutane (DHBMA, from HMVK) and 4-(N-acetyl-L-cystein-S-yl)-1,2,3-trihydroxybutane (THBMA, from EBD), in urine of confirmed smokers, occupationally exposed workers and BD-exposed laboratory rats. Bis-BDMA was formed in a dose-dependent manner in urine of rats exposed to 0-200 p.p.m. BD by inhalation, although it was a minor metabolite (1%) as compared with DHBMA (47%) and THBMA (37%). In humans, DHBMA was the most abundant BD-mercapturic acid excreted (93%), followed by THBMA (5%) and MHBMA (2%), whereas no bis-BDMA was detected. These results reveal significant differences in metabolism of BD between rats and humans.
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Affiliation(s)
- Srikanth Kotapati
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA, Sealy Center for Environmental Health and Medicine (SCEHM) and the Department of Preventive Medicine and Community Health, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA, Department of Pathology, University of Vermont, Burlington, VT 05405, USA and Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Dewakar Sangaraju
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA, Sealy Center for Environmental Health and Medicine (SCEHM) and the Department of Preventive Medicine and Community Health, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA, Department of Pathology, University of Vermont, Burlington, VT 05405, USA and Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Amanda Esades
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA, Sealy Center for Environmental Health and Medicine (SCEHM) and the Department of Preventive Medicine and Community Health, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA, Department of Pathology, University of Vermont, Burlington, VT 05405, USA and Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lance Hallberg
- Sealy Center for Environmental Health and Medicine (SCEHM) and the Department of Preventive Medicine and Community Health, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Vernon E Walker
- Department of Pathology, University of Vermont, Burlington, VT 05405, USA and
| | - James A Swenberg
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Natalia Y Tretyakova
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA, Sealy Center for Environmental Health and Medicine (SCEHM) and the Department of Preventive Medicine and Community Health, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA, Department of Pathology, University of Vermont, Burlington, VT 05405, USA and Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Pottenger LH, Andrews LS, Bachman AN, Boogaard PJ, Cadet J, Embry MR, Farmer PB, Himmelstein MW, Jarabek AM, Martin EA, Mauthe RJ, Persaud R, Preston RJ, Schoeny R, Skare J, Swenberg JA, Williams GM, Zeiger E, Zhang F, Kim JH. An organizational approach for the assessment of DNA adduct data in risk assessment: case studies for aflatoxin B1, tamoxifen and vinyl chloride. Crit Rev Toxicol 2014; 44:348-91. [DOI: 10.3109/10408444.2013.873768] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Lu K, Mahbub R, Cable PH, Ru H, Parry NMA, Bodnar WM, Wishnok JS, Styblo M, Swenberg JA, Fox JG, Tannenbaum SR. Gut microbiome phenotypes driven by host genetics affect arsenic metabolism. Chem Res Toxicol 2014; 27:172-4. [PMID: 24490651 PMCID: PMC3997221 DOI: 10.1021/tx400454z] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
Large
individual differences in susceptibility to arsenic-induced
diseases are well-documented and frequently associated with different
patterns of arsenic metabolism. In this context, the role of the gut
microbiome in directly metabolizing arsenic and triggering systemic
responses in diverse organs raises the possibility that gut microbiome
phenotypes affect the spectrum of metabolized arsenic species. However,
it remains unclear how host genetics and the gut microbiome interact
to affect the biotransformation of arsenic. Using an integrated approach
combining 16S rRNA gene sequencing and HPLC-ICP-MS arsenic speciation,
we demonstrate that IL-10 gene knockout leads to a significant taxonomic
change of the gut microbiome, which in turn substantially affects
arsenic metabolism.
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Affiliation(s)
- Kun Lu
- Department of Biological Engineering, ‡Division of Comparative Medicine, and §Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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Rager JE, Moeller BC, Miller SK, Kracko D, Doyle-Eisele M, Swenberg JA, Fry RC. Formaldehyde-associated changes in microRNAs: tissue and temporal specificity in the rat nose, white blood cells, and bone marrow. Toxicol Sci 2013; 138:36-46. [PMID: 24304932 DOI: 10.1093/toxsci/kft267] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
MicroRNAs (miRNAs) are critical regulators of gene expression, yet much remains unknown regarding their changes resulting from environmental exposures as they influence cellular signaling across various tissues. We set out to investigate miRNA responses to formaldehyde, a critical air pollutant and known carcinogen that disrupts miRNA expression profiles. Rats were exposed by inhalation to either 0 or 2 ppm formaldehyde for 7, 28, or 28 days followed by a 7-day recovery. Genome-wide miRNA expression profiles were assessed within the nasal respiratory epithelium, circulating white blood cells (WBC), and bone marrow (BM). miRNAs showed altered expression in the nose and WBC but not in the BM. Notably in the nose, miR-10b and members of the let-7 family, known nasopharyngeal carcinoma players, showed decreased expression. To integrate miRNA responses with transcriptional changes, genome-wide messenger RNA profiles were assessed in the nose and WBC. Although formaldehyde-induced changes in miRNA and transcript expression were largely tissue specific, pathway analyses revealed an enrichment of immune system/inflammation signaling in the nose and WBC. Specific to the nose was enrichment for apoptosis/proliferation signaling, involving let-7a, let-7c, and let-7f. Across all tissues and time points assessed, miRNAs were predicted to regulate between 7% and 35% of the transcriptional responses and were suggested to play a role in signaling processes including immune/inflammation-related pathways. These data inform our current hypothesis that formaldehyde-induced inflammatory signals originating in the nose may drive WBC effects.
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Affiliation(s)
- Julia E Rager
- * Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, North Carolina 27599
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Lu K, Cable PH, Abo RP, Ru H, Graffam ME, Schlieper KA, Parry NMA, Levine S, Bodnar WM, Wishnok JS, Styblo M, Swenberg JA, Fox JG, Tannenbaum SR. Gut microbiome perturbations induced by bacterial infection affect arsenic biotransformation. Chem Res Toxicol 2013; 26:1893-903. [PMID: 24134150 DOI: 10.1021/tx4002868] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Exposure to arsenic affects large human populations worldwide and has been associated with a long list of human diseases, including skin, bladder, lung, and liver cancers, diabetes, and cardiovascular disorders. In addition, there are large individual differences in susceptibility to arsenic-induced diseases, which are frequently associated with different patterns of arsenic metabolism. Several underlying mechanisms, such as genetic polymorphisms and epigenetics, have been proposed, as these factors closely impact the individuals' capacity to metabolize arsenic. In this context, the role of the gut microbiome in directly metabolizing arsenic and triggering systemic responses in diverse organs raises the possibility that perturbations of the gut microbial communities affect the spectrum of metabolized arsenic species and subsequent toxicological effects. In this study, we used an animal model with an altered gut microbiome induced by bacterial infection, 16S rRNA gene sequencing, and inductively coupled plasma mass spectrometry-based arsenic speciation to examine the effect of gut microbiome perturbations on the biotransformation of arsenic. Metagenomics sequencing revealed that bacterial infection significantly perturbed the gut microbiome composition in C57BL/6 mice, which in turn resulted in altered spectra of arsenic metabolites in urine, with inorganic arsenic species and methylated and thiolated arsenic being perturbed. These data clearly illustrated that gut microbiome phenotypes significantly affected arsenic metabolic reactions, including reduction, methylation, and thiolation. These findings improve our understanding of how infectious diseases and environmental exposure interact and may also provide novel insight regarding the gut microbiome composition as a new risk factor of individual susceptibility to environmental chemicals.
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Affiliation(s)
- Kun Lu
- Department of Biological Engineering, ‡Department of Biology, §Division of Comparative Medicine, and ∥Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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Edrissi B, Taghizadeh K, Moeller BC, Kracko D, Doyle-Eisele M, Swenberg JA, Dedon PC. Dosimetry of N⁶-formyllysine adducts following [¹³C²H₂]-formaldehyde exposures in rats. Chem Res Toxicol 2013; 26:1421-3. [PMID: 24087891 PMCID: PMC3805309 DOI: 10.1021/tx400320u] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
With formaldehyde as the major source
of endogenous N6-formyllysine protein
adducts, we quantified endogenous
and exogenous N6-formyllysine in the nasal
epithelium of rats exposed by inhalation to 0.7, 2, 5.8, and 9.1 ppm
[13C2H2]-formaldehyde using liquid
chromatography-coupled tandem mass spectrometry. Exogenous N6-formyllysine was detected in the nasal epithelium,
with concentration-dependent formation in total as well as fractionated
(cytoplasmic, membrane, nuclear) proteins, but was not detected in
the lung, liver, or bone marrow. Endogenous adducts dominated at all
exposure conditions, with a 6 h 9.1 ppm formaldehyde exposure resulting
in one-third of the total load of N6-formyllysine
being derived from exogenous sources. The results parallel previous
studies of formaldehyde-induced DNA adducts.
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Affiliation(s)
- Bahar Edrissi
- Department of Biological Engineering, ‡Center for Environmental Health Sciences, Massachusetts Institute of Technology , Cambridge, Massachusetts, 02139, United States
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Foley JF, Dietrich DR, Swenberg JA, Maronpot RR. Detection and Evaluation of Proliferating Cell Nuclear Antigen (PCNA) in Rat Tissue by an Improved Immunohistochemical Procedure. J Histotechnol 2013. [DOI: 10.1179/his.1991.14.4.237] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Moeller BC, Recio L, Green A, Sun W, Wright FA, Bodnar WM, Swenberg JA. Biomarkers of exposure and effect in human lymphoblastoid TK6 cells following [13C2]-acetaldehyde exposure. Toxicol Sci 2013; 133:1-12. [PMID: 23425604 PMCID: PMC3627555 DOI: 10.1093/toxsci/kft029] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 02/11/2013] [Indexed: 01/13/2023] Open
Abstract
The dose-response relationship for biomarkers of exposure (N(2)-ethylidene-dG adducts) and effect (cell survival and micronucleus formation) was determined across 4.5 orders of magnitude (50nM-2mM) using [(13)C2]-acetaldehyde exposures to human lymphoblastoid TK6 cells for 12h. There was a clear increase in exogenous N (2)-ethylidene-dG formation at exposure concentrations ≥ 1µM, whereas the endogenous adducts remained nearly constant across all exposure concentrations, with an average of 3.0 adducts/10(7) dG. Exogenous adducts were lower than endogenous adducts at concentrations ≤ 10µM and were greater than endogenous adducts at concentrations ≥ 250µM. When the endogenous and exogenous adducts were summed together, statistically significant increases in total adduct formation over the endogenous background occurred at 50µM. Cell survival and micronucleus formation were monitored across the exposure range and statistically significant decreases in cell survival and increases in micronucleus formation occurred at ≥ 1000µM. This research supports the hypothesis that endogenously produced reactive species, including acetaldehyde, are always present and constitute the majority of the observed biological effects following very low exposures to exogenous acetaldehyde. These data can replace default assumptions of linear extrapolation to very low doses of exogenous acetaldehyde for risk prediction.
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Affiliation(s)
- Benjamin C. Moeller
- *Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599
| | | | | | - Wei Sun
- ‡Biostatistics, Gillings School of Global Public Health
- §Department of Genetics, School of Medicine, and
| | | | - Wanda M. Bodnar
- ¶Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599
| | - James A. Swenberg
- *Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599
- ¶Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599
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Rager JE, Moeller BC, Doyle-Eisele M, Kracko D, Swenberg JA, Fry RC. Formaldehyde and epigenetic alterations: microRNA changes in the nasal epithelium of nonhuman primates. Environ Health Perspect 2013; 121:339-44. [PMID: 23322811 PMCID: PMC3621188 DOI: 10.1289/ehp.1205582] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 01/14/2013] [Indexed: 05/05/2023]
Abstract
BACKGROUND Formaldehyde is an air pollutant present in both indoor and outdoor atmospheres. Because of its ubiquitous nature, it is imperative to understand the mechanisms underlying formaldehyde-induced toxicity and carcinogenicity. MicroRNAs (miRNAs) can influence disease caused by environmental exposures, yet miRNAs are understudied in relation to formaldehyde. Our previous investigation demonstrated that formaldehyde exposure in human lung cells caused disruptions in miRNA expression profiles in vitro. OBJECTIVES Using an in vivo model, we set out to test the hypothesis that formaldehyde inhalation exposure significantly alters miRNA expression profiles within the nasal epithelium of nonhuman primates. METHODS Cynomolgus macaques were exposed by inhalation to approximately 0, 2, or 6 ppm formaldehyde for 6 hr/day for 2 consecutive days. Small RNAs were extracted from nasal samples and assessed for genome-wide miRNA expression levels. Transcriptional targets of formaldehyde-altered miRNAs were computationally predicted, analyzed at the systems level, and assessed using real-time reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS Expression analysis revealed that 3 and 13 miRNAs were dysregulated in response to 2 and 6 ppm formaldehyde, respectively. Transcriptional targets of the miRNA with the greatest increase (miR-125b) and decrease (miR-142-3p) in expression were predicted and analyzed at the systems level. Enrichment was identified for miR-125b targeting genes involved in apoptosis signaling. The apoptosis-related targets were functionally tested using RT-PCR, where all targets showed decreased expression in formaldehyde-exposed samples. CONCLUSIONS Formaldehyde exposure significantly disrupts miRNA expression profiles within the nasal epithelium, and these alterations likely influence apoptosis signaling.
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Affiliation(s)
- Julia E Rager
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Swenberg JA, Moeller BC, Lu K, Rager JE, Fry RC, Starr TB. Formaldehyde carcinogenicity research: 30 years and counting for mode of action, epidemiology, and cancer risk assessment. Toxicol Pathol 2012; 41:181-9. [PMID: 23160431 DOI: 10.1177/0192623312466459] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Formaldehyde is a widely used high production chemical that is also released as a byproduct of combustion, off-gassing of various building products, and as a fixative for pathologists and embalmers. What is not often realized is that formaldehyde is also produced as a normal physiologic chemical in all living cells. In 1980, chronic inhalation of high concentrations of formaldehyde was shown to be carcinogenic, inducing a high incidence of nasal squamous cell carcinomas in rats. Some epidemiologic studies have also found increased numbers of nasopharyngeal carcinoma and leukemia in humans exposed to formaldehyde that resulted in formaldehyde being considered a Known Human Carcinogen. This article reviews the data for rodent and human carcinogenicity, early Mode of Action studies, more recent molecular studies of both endogenous and exogenous DNA adducts, and epigenetic studies. It goes on to demonstrate the power of these research studies to provide critical data to improve our ability to develop science-based cancer risk assessments, instead of default approaches. The complexity of constant physiologic exposure to a known carcinogen requires that new ways of thinking be incorporated into determinations of cancer risk assessment for formaldehyde, other endogenous carcinogens, and the role of background endogenous DNA damage and mutagenesis.
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Affiliation(s)
- James A Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Kotapati S, Sangaraju D, Walker VE, Swenberg JA, Tretyakova NY. Abstract 4473: Urinary biomarkers of exposure to 1,3-Butadiene and its bioactivation to DNA-reactive metabolites. Cancer Res 2012. [DOI: 10.1158/1538-7445.am2012-4473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
1,3-butadiene (BD) is one of the most potent and abundant carcinogens present in cigarette smoke. BD is metabolically activated to 3,4-epoxy-1-butene (EB), 1,2,3,4-diepoxy butane (DEB), hydroxymethylvinylketone (HMVK), and 3,4-epoxy-1,2-butanediol (EBD), which can react with DNA nucleobases and proteins to form promutagenic adducts. Alternatively, these electrophilic metabolites can be detoxified via hydrolysis or conjugation with glutathione. The glutathione conjugates of these metabolites are ultimately excreted in urine as 1-hydroxy 2-(N-acetylcysteinyl)-3-butene (MHBMA), 1,4-bis-(N-acetylcysteinyl)butane-2,3-diol (bis-BDMA), 1,2-dihydroxy-4-(N-acetylcysteinyl)-butane (DHBMA), and 1,2,3-trihydroxy-4-(N-acetylcysteinyl)-butane (THBMA), respectively. Since epoxide metabolites of BD are thought to be responsible for its adverse health effects, it is important to develop specific biomarkers of their formation in vivo to be used in molecular epidemiology studies. While MHBMA, DHBMA, THBMA have been previously detected in smoker's urine, bis-BDMA has not been reported. In the present study, novel stable isotope dilution HPLC-ESI-MS/MS methods for accurate and precise quantification of MHBMA, DHBMA, THBMA, and bis-BDMA in urine have been developed. Dose dependent formation of all BD-mercapturic acids including bis-BDMA was observed in urine samples from male and female F344 rats exposed to 0, 62.5 and 200 ppm of BD for 2 weeks by inhalation. The relative amounts of MHBMA, DHBMA, THBMA, and bis-BDMA in rat urine were 20:50:50:1. Furthermore, MHBMA, DHBMA, and THBMA were detected in urine samples from known smokers and non-smokers, with significantly higher concentrations observed in smokers. The mean levels of these BD-mercapturic acids in smokers were 3, 340, and 27 ng/mg creatinine, respectively. In contrast, bis-BDMA could not be detected in human urine samples, probably a result of the inefficient DEB formation in humans. These methods are now being applied to a multi-ethnic cohort study to identify any differences in metabolism that contribute to ethnic and inter-individual differences in lung cancer incidence.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4473. doi:1538-7445.AM2012-4473
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Mutlu E, Jeong YC, Collins LB, Ham AJL, Upton PB, Hatch G, Winsett D, Evansky P, Swenberg JA. A new LC-MS/MS method for the quantification of endogenous and vinyl chloride-induced 7-(2-Oxoethyl)guanine in sprague-dawley rats. Chem Res Toxicol 2012; 25:391-9. [PMID: 22211352 PMCID: PMC3288741 DOI: 10.1021/tx200447w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Vinyl chloride (VC) is an industrial chemical that is known to be carcinogenic to animals and humans. VC primarily induces hepatic angiosarcomas following high exposures (≥50 ppm). VC is also found in Superfund sites at ppb concentrations as a result of microbial metabolism of trichloroethylene and perchloroethylene. Here, we report a new sensitive LC-MS/MS method to analyze the major DNA adduct formed by VC, 7-(2-oxoethylguanine) (7-OEG). We used this method to analyze tissue DNA from both adult and weanling rats exposed to 1100 ppm [(13)C(2)]-VC for 5 days. After neutral thermal hydrolysis, 7-OEG was derivatized with O-t-butyl hydroxylamine to an oxime adduct, followed by LC-MS/MS analysis. The limit of detection was 1 fmol, and the limit of quantitation was 1.5 fmol on the column. The use of stable isotope VC allowed us to demonstrate for the first time that endogenous 7-OEG was present in tissue DNA. We hypothesized that endogenous 7-OEG was formed from lipid peroxidation and demonstrated the formation of [(13)C(2)]-7-OEG from the reaction of calf thymus DNA with [(13)C(18)]-ethyl linoleate (EtLa) under peroxidizing conditions. The concentrations of endogenous 7-OEG in liver, lung, kidney, spleen, testis, and brain DNA from adult and weanling rats typically ranged from 1.0 to 10.0 adducts per 10(6) guanine. The exogenous 7-OEG in liver DNA from adult rats exposed to 1100 ppm [(13)C(2)]-VC for 5 days was 104.0 ± 23.0 adducts per 10(6) guanine (n = 4), while concentrations in other tissues ranged from 1.0 to 39.0 adducts per 10(6) guanine (n = 4). Although endogenous concentrations of 7-OEG in tissues in weanling rats were similar to those of adult rats, exogenous [(13)C(2)]-7-OEG concentrations were higher in weanlings, averaging 300 adducts per 10(6) guanine in liver. Studies on the persistence of [(13)C(2)]-7-OEG in adult rats sacrificed 2, 4, and 8 weeks postexposure to [(13)C(2)]-VC demonstrated a half-life of 7-OEG of 4 days in both liver and lung.
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Affiliation(s)
- Esra Mutlu
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Curriculum in Toxicology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Yo-Chan Jeong
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Leonard B. Collins
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Amy-Joan L. Ham
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Patricia B. Upton
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | | | | | | | - James A. Swenberg
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Curriculum in Toxicology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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Lu K, Craft S, Nakamura J, Moeller BC, Swenberg JA. Use of LC-MS/MS and stable isotopes to differentiate hydroxymethyl and methyl DNA adducts from formaldehyde and nitrosodimethylamine. Chem Res Toxicol 2012; 25:664-75. [PMID: 22148432 DOI: 10.1021/tx200426b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Formaldehyde is a known human and animal carcinogen that forms DNA adducts, and causes mutations. While there is widespread exposure to formaldehyde in the environment, formaldehyde is also an essential biochemical in all living cells. The presence of both endogenous and exogenous sources of formaldehyde makes it difficult to develop exposure-specific DNA biomarkers. Furthermore, chemicals such as nitrosodimethylamine form one mole of formaldehyde for every mole of methylating agent, raising questions about potential cocarcinogenesis. Formaldehyde-induced hydroxymethyl DNA adducts are not stable and need to be reduced to stable methyl adducts for detection, which adds another layer of complexity to identifying the origins of these adducts. In this study, highly sensitive mass spectrometry methods and isotope labeled compounds were used to differentiate between endogenous and exogenous hydroxymethyl and methyl DNA adducts. We demonstrate that N(2)-hydroxymethyl-dG is the primary DNA adduct formed in cells following formaldehyde exposure. In addition, we show that alkylating agents induce methyl adducts at N(2)-dG and N(6)-dA positions, which are identical to the reduced forms of hydroxymethyl adducts arising from formaldehyde. The use of highly sensitive LC-MS/MS and isotope labeled compounds for exposure solves these challenges and provides mechanistic insights on the formation and role of these DNA adducts.
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Affiliation(s)
- Kun Lu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Boysen G, Georgieva NI, Bordeerat NK, Šram RJ, Vacek P, Albertini RJ, Swenberg JA. Formation of 1,2:3,4-diepoxybutane-specific hemoglobin adducts in 1,3-butadiene exposed workers. Toxicol Sci 2012; 125:30-40. [PMID: 22003190 PMCID: PMC3243749 DOI: 10.1093/toxsci/kfr272] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/04/2011] [Indexed: 11/14/2022] Open
Abstract
1,3-Butadiene (BD) is an important industrial chemical that is classified as a human carcinogen. BD carcinogenicity has been attributed to its metabolism to several reactive epoxide metabolites and formation of the highly mutagenic 1,2:3,4-diepoxybutane (DEB) has been hypothesized to drive mutagenesis and carcinogenesis at exposures experienced in humans. We report herein the formation of DEB-specific N,N-(2,3-dihydroxy-1,4-butadiyl)valine (pyr-Val) in BD-exposed workers as a biomarker of DEB formation. pyr-Val was determined in BD monomer and polymer plant workers that had been previously analyzed for several other biomarkers of exposure and effect. pyr-Val was detected in 68 of 81 (84%) samples ranging from 0.08 to 0.86 pmol/g globin. Surprisingly, pyr-Val was observed in 19 of 23 administrative control subjects not known to be exposed to BD, suggesting exposure from environmental sources of BD. The mean ± SD amounts of pyr-Val were 0.11 ± 0.07, 0.16 ± 0.12, and 0.29 ± 0.20 pmol/g globin in the controls, monomer, and polymer workers, respectively, clearly demonstrating formation of DEB in humans. The amounts of pyr-Val found in this study suggest that humans are much less efficient in the formation of DEB than mice or rats at similar exposures. Formation of pyr-Val was more than 50-fold lower than has been associated with increased mutagenesis in rodents. The results further suggest that formation of DEB relative to other epoxides is significantly different in the highest exposed polymer workers compared with controls and BD monomer workers. Whether this is due to saturation of metabolic formation or increased GST-mediated detoxification could not be determined.
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Affiliation(s)
- Gunnar Boysen
- Department of Environmental and Occupational Health and The Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
- Department of Environmental Sciences and Engineering
- Center for Environmental Health and Susceptibility, The University of North Carolina at Chapel Hill, Gillings School of Global Public Health, Chapel Hill, North Carolina 27599
| | | | | | - Radim J. Šram
- Department of Genetic Ecotoxicology, Laboratory of Genetic Ecotoxicology, 142 20 Prague, Czech Republic
| | - Pamela Vacek
- Department of Pathology, University of Vermont, Burlington, Vermont 05405
| | | | - James A. Swenberg
- Department of Environmental Sciences and Engineering
- Center for Environmental Health and Susceptibility, The University of North Carolina at Chapel Hill, Gillings School of Global Public Health, Chapel Hill, North Carolina 27599
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45
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Lu K, Gul H, Upton PB, Moeller BC, Swenberg JA. Formation of hydroxymethyl DNA adducts in rats orally exposed to stable isotope labeled methanol. Toxicol Sci 2011; 126:28-38. [PMID: 22157354 DOI: 10.1093/toxsci/kfr328] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Methanol is a large volume industrial chemical and widely used solvent and fuel additive. Methanol's well known toxicity and use in a wide spectrum of applications has raised long-standing environmental issues over its safety, including its carcinogenicity. Methanol has not been listed as a carcinogen by any regulatory agency; however, there are debates about its carcinogenic potential. Formaldehyde, a metabolite of methanol, has been proposed to be responsible for the carcinogenesis of methanol. Formaldehyde is a known carcinogen and actively targets DNA and protein, causing diverse DNA and protein damage. However, formaldehyde-induced DNA adducts arising from the metabolism of methanol have not been reported previously, largely due to the absence of suitable DNA biomarkers and the inability to differentiate what was due to methanol compared with the substantial background of endogenous formaldehyde. Recently, we developed a unique approach combining highly sensitive liquid chromatography-mass spectrometry methods and exposure to stable isotope labeled chemicals to simultaneously quantify formaldehyde-specific endogenous and exogenous DNA adducts. In this study, rats were exposed daily to 500 or 2000 mg/kg [¹³CD₄]-methanol by gavage for 5 days. Our data demonstrate that labeled formaldehyde arising from [¹³CD₄]-methanol induced hydroxymethyl DNA adducts in multiple tissues in a dose-dependent manner. The results also demonstrated that the number of exogenous DNA adducts was lower than the number of endogenous hydroxymethyl DNA adducts in all tissues of rats administered 500 mg/kg per day for 5 days, a lethal dose to humans, even after incorporating an average factor of 4 for reduced metabolism due to isotope effects of deuterium-labeled methanol into account.
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Affiliation(s)
- Kun Lu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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46
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Jung D, Matson CW, Collins LB, Laban G, Stapleton HM, Bickham JW, Swenberg JA, Giulio RTD. Genotoxicity in Atlantic killifish (Fundulus heteroclitus) from a PAH-contaminated Superfund site on the Elizabeth River, Virginia. Ecotoxicology 2011; 20:1890-9. [PMID: 21706406 PMCID: PMC3203518 DOI: 10.1007/s10646-011-0727-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/18/2011] [Indexed: 05/03/2023]
Abstract
The Atlantic Wood Industries Superfund site (AWI) on the Elizabeth River in Portsmouth, VA is heavily contaminated with polycyclic aromatic hydrocarbons (PAHs) from a wood treatment facility. Atlantic killifish, or mummichog (Fundulus heteroclitus), at this Superfund site are exposed to very high concentrations of several carcinogens. In this study, we measured PAH concentrations in both fish tissues and sediments. Concurrently, we assessed different aspects of genotoxicity in the killifish exposed in situ. Both sediment and tissue PAH levels were significantly higher in AWI samples, relative to a reference site, but the chemistry profile was different between sediments and tissues. Killifish at AWI exhibited higher levels of DNA damage compared to reference fish, as measured via the flow cytometric method (FCM), and the damage was consistent with sediment PAH concentrations. Covalent binding of benzo[a]pyrene (BaP) metabolites to DNA, as measured via LC-MS/MS adduct detection methods, were also elevated and could be partially responsible for the DNA damage. Using similar LC-MS/MS methods, we found no evidence that oxidative DNA adducts had a role in observed genotoxicity.
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Affiliation(s)
- Dawoon Jung
- Nicholas School of the Environment, Duke University, Durham, NC 27708
- Department of Physiology, Dartmouth Medical School, Hanover, NH 03755
| | - Cole W. Matson
- Nicholas School of the Environment, Duke University, Durham, NC 27708
- Center for the Environmental Implications of NanoTechnology (CEINT), Duke University, Durham, NC 27708
| | - Leonard B. Collins
- Center for Environmental Health and Susceptibility, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599
| | - Geoff Laban
- Center for the Environment, Purdue University, W. Lafayette, IN 47907
| | | | - John W. Bickham
- Center for the Environment, Purdue University, W. Lafayette, IN 47907
| | - James A. Swenberg
- Center for Environmental Health and Susceptibility, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599
| | - Richard T. Di Giulio
- Nicholas School of the Environment, Duke University, Durham, NC 27708
- Corresponding Author: Richard T. Di Giulio Nicholas School of the Environment Duke University Box 90328 Durham, NC 27708-0328 (919) 613-8024
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Abstract
5-methylcytosine (5mC) in DNA plays an important role in gene expression, genomic imprinting, and suppression of transposable elements. 5mC can be converted to 5-hydroxymethylcytosine (5hmC) by the Tet (ten eleven translocation) proteins. Here, we show that, in addition to 5hmC, the Tet proteins can generate 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) from 5mC in an enzymatic activity-dependent manner. Furthermore, we reveal the presence of 5fC and 5caC in genomic DNA of mouse embryonic stem cells and mouse organs. The genomic content of 5hmC, 5fC, and 5caC can be increased or reduced through overexpression or depletion of Tet proteins. Thus, we identify two previously unknown cytosine derivatives in genomic DNA as the products of Tet proteins. Our study raises the possibility that DNA demethylation may occur through Tet-catalyzed oxidation followed by decarboxylation.
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Affiliation(s)
- Shinsuke Ito
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
| | - Li Shen
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
| | - Qing Dai
- Department of Chemistry and Institute for Biophysical Dynamics, the University of Chicago, Chicago, Illinois, USA
| | - Susan C. Wu
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
| | - Leonard B. Collins
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
| | - James A. Swenberg
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
| | - Chuan He
- Department of Chemistry and Institute for Biophysical Dynamics, the University of Chicago, Chicago, Illinois, USA
| | - Yi Zhang
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295
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48
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Wu KY, Chiang SY, Shih WC, Huang CCJ, Chen MF, Swenberg JA. The application of mass spectrometry in molecular dosimetry: ethylene oxide as an example. Mass Spectrom Rev 2011; 30:733-756. [PMID: 21328599 DOI: 10.1002/mas.20299] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Mass spectrometry plays an increasingly important role in the search for and quantification of novel chemically specific biomarkers. The revolutionary advances in mass spectrometry instrumentation and technology empower scientists to specifically analyze DNA and protein adducts, considered as molecular dosimeters, derived from reactions of a carcinogen or its active metabolites with DNA or protein. Analysis of the adducted DNA bases and proteins can elucidate the chemically reactive species of carcinogens in humans and can serve as risk-associated biomarkers for early prediction of cancer risk. In this article, we review and compare the specificity, sensitivity, resolution, and ease-of-use of mass spectrometry methods developed to analyze ethylene oxide (EO)-induced DNA and protein adducts, particularly N7-(2-hydroxyethyl)guanine (N7-HEG) and N-(2-hydroxyethyl)valine (HEV), in human samples and in animal tissues. GC/ECNCI-MS analysis after HPLC cleanup is the most sensitive method for quantification of N7-HEG, but limited by the tedious sample preparation procedures. Excellent sensitivity and specificity in analysis of N7-HEG can be achieved by LC/MS/MS analysis if the mobile phase, the inlet (split or splitless), and the collision energy are properly optimized. GC/ECNCI-HRMS and GC/ECNCI-MS/MS analysis of HEV achieves the best performance as compared with GC/ECNCI-MS and GC/EI-MS. In conclusion, future improvements in high-throughput capabilities, detection sensitivity, and resolution of mass spectrometry will attract more scientists to identify and/or quantify novel molecular dosimeters or profiles of these biomarkers in toxicological and/or epidemiological studies.
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Affiliation(s)
- Kuen-Yuh Wu
- Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan.
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49
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Swenberg JA, Bordeerat NK, Boysen G, Carro S, Georgieva NI, Nakamura J, Troutman JM, Upton PB, Albertini RJ, Vacek PM, Walker VE, Sram RJ, Goggin M, Tretyakova N. Corrigendum to “1,3-Butadiene: Biomarkers and application to risk assessment” [Chem. Biol. Interact. 192(1–2) (2011) 150–154]. Chem Biol Interact 2011. [DOI: 10.1016/j.cbi.2011.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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50
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Bhattacharyya D, Ramachandran S, Sharma S, Pathmasiri W, King CL, Baskerville-Abraham I, Boysen G, Swenberg JA, Campbell SL, Dokholyan NV, Chaney SG. Flanking bases influence the nature of DNA distortion by platinum 1,2-intrastrand (GG) cross-links. PLoS One 2011; 6:e23582. [PMID: 21853154 PMCID: PMC3154474 DOI: 10.1371/journal.pone.0023582] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 07/21/2011] [Indexed: 11/28/2022] Open
Abstract
The differences in efficacy and molecular mechanisms of platinum anti-cancer drugs cisplatin (CP) and oxaliplatin (OX) are thought to be partially due to the differences in the DNA conformations of the CP and OX adducts that form on adjacent guanines on DNA, which in turn influence the binding of damage-recognition proteins that control downstream effects of the adducts. Here we report a comprehensive comparison of the structural distortion of DNA caused by CP and OX adducts in the TGGT sequence context using nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations. When compared to our previous studies in other sequence contexts, these structural studies help us understand the effect of the sequence context on the conformation of Pt-GG DNA adducts. We find that both the sequence context and the type of Pt-GG DNA adduct (CP vs. OX) play an important role in the conformation and the conformational dynamics of Pt-DNA adducts, possibly explaining their influence on the ability of many damage-recognition proteins to bind to Pt-DNA adducts.
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Affiliation(s)
- Debadeep Bhattacharyya
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Srinivas Ramachandran
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Program in Cellular and Molecular Biophysics, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Shantanu Sharma
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Wimal Pathmasiri
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Candice L. King
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Irene Baskerville-Abraham
- Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Gunnar Boysen
- Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - James A. Swenberg
- Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Sharon L. Campbell
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
- * E-mail: (SLC); (NVD); (SGC)
| | - Nikolay V. Dokholyan
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
- * E-mail: (SLC); (NVD); (SGC)
| | - Stephen G. Chaney
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
- * E-mail: (SLC); (NVD); (SGC)
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