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Dorrell C, Peters AM, Zhang Q, Balaji N, Baradar K, Mochizuki-Kashio M, Major A, Finegold M, Liu CW, Lu K, Grompe M. Long-term combination therapy with metformin and oxymetholone in a Fanconi anemia mouse model. Pediatr Blood Cancer 2024; 71:e31030. [PMID: 38733122 DOI: 10.1002/pbc.31030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 03/25/2024] [Accepted: 04/09/2024] [Indexed: 05/13/2024]
Abstract
Fanconi anemia (FA) is a disease caused by defective deoxyribonucleic acid (DNA) repair that manifests as bone marrow failure, cancer predisposition, and developmental defects. We previously reported that monotherapy with either metformin (MET) or oxymetholone (OXM) improved peripheral blood (PB) counts and the number and functionality of bone marrow hematopoietic stem progenitor cells (HSPCs) number in Fancd2-/- mice. To evaluate whether the combination treatment of these drugs has a synergistic effect to prevent bone marrow failure in FA, we treated cohorts of Fancd2-/- mice and wildtype controls with either MET alone, OXM alone, MET+OXM, or placebo diet from age 3 weeks to 18 months. The OXM treated animals showed modest improvements in blood parameters including platelet count (p = .01) and hemoglobin levels (p < .05). In addition, the percentage of quiescent hematopoietic stem cell (HSC) (LSK [Lin-Sca+c-Kit+]) was significantly increased (p = .001) by long-term treatment with MET alone. The combination of metformin and oxymetholone did not result in a significant synergistic effect in any hematopoietic parameter. Gene expression analysis of liver tissue from these animals showed that some of the expression changes caused by Fancd2 deletion were partially normalized by metformin treatment. Importantly, no adverse effects of the individual or combination therapies were observed, despite the long-term administration. We conclude that androgen therapy is not a contraindication to concurrent metformin administration in clinical trials. HIGHLIGHTS: Long-term coadministration of metformin in combination with oxymetholone is well tolerated by Fancd2-/- mice. Hematopoietic stem cell quiescence in mutant mice was enhanced by treatment with metformin alone. Metformin treatment caused a partial normalization of gene expression in the livers of mutant mice.
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Affiliation(s)
- Craig Dorrell
- Department of Pediatrics, Papé Family Pediatric Research Institute, Stem Cell Center, Pediatric Blood & Cancer Biology Program, Oregon Health & Science University, Portland, Oregon, USA
| | - Alexander M Peters
- Department of Pediatrics, Papé Family Pediatric Research Institute, Stem Cell Center, Pediatric Blood & Cancer Biology Program, Oregon Health & Science University, Portland, Oregon, USA
| | - Qingshuo Zhang
- Department of Pediatrics, Papé Family Pediatric Research Institute, Stem Cell Center, Pediatric Blood & Cancer Biology Program, Oregon Health & Science University, Portland, Oregon, USA
| | - Niveditha Balaji
- Department of Pediatrics, Papé Family Pediatric Research Institute, Stem Cell Center, Pediatric Blood & Cancer Biology Program, Oregon Health & Science University, Portland, Oregon, USA
| | - Kevin Baradar
- Department of Pediatrics, Papé Family Pediatric Research Institute, Stem Cell Center, Pediatric Blood & Cancer Biology Program, Oregon Health & Science University, Portland, Oregon, USA
| | - Makiko Mochizuki-Kashio
- Department of Pediatrics, Papé Family Pediatric Research Institute, Stem Cell Center, Pediatric Blood & Cancer Biology Program, Oregon Health & Science University, Portland, Oregon, USA
| | - Angela Major
- Department of Pathology, Texas Children's Hospital, Houston, Texas, USA
| | - Milton Finegold
- Department of Pathology, Texas Children's Hospital, Houston, Texas, USA
| | - Chih-Wei Liu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Kun Lu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Markus Grompe
- Department of Pediatrics, Papé Family Pediatric Research Institute, Stem Cell Center, Pediatric Blood & Cancer Biology Program, Oregon Health & Science University, Portland, Oregon, USA
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2
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Möller C, Virzi J, Chang YJ, Keidel A, Chao MR, Hu CW, Cooke MS. DNA modifications: Biomarkers for the exposome? ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2024; 108:104449. [PMID: 38636743 DOI: 10.1016/j.etap.2024.104449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 03/25/2024] [Accepted: 04/12/2024] [Indexed: 04/20/2024]
Abstract
The concept of the exposome is the encompassing of all the environmental exposures, both exogenous and endogenous, across the life course. Many, if not all, of these exposures can result in the generation of reactive species, and/or the modulation of cellular processes, that can lead to a breadth of modifications of DNA, the nature of which may be used to infer their origin. Because of their role in cell function, such modifications have been associated with various major human diseases, including cancer, and so their assessment is crucial. Historically, most methods have been able to only measure one or a few DNA modifications at a time, limiting the information available. With the development of DNA adductomics, which aims to determine the totality of DNA modifications, a far more comprehensive picture of the DNA adduct burden can be gained. Importantly, DNA adductomics can facilitate a "top-down" investigative approach whereby patterns of adducts may be used to trace and identify the originating exposure source. This, together with other 'omic approaches, represents a major tool for unraveling the complexities of the exposome and hence allow a better a understanding of the environmental origins of disease.
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Affiliation(s)
- Carolina Möller
- Oxidative Stress Group, Department of Molecular Biosciences, University of South Florida, Tampa, FL 33620, USA.
| | - Jazmine Virzi
- Oxidative Stress Group, Department of Molecular Biosciences, University of South Florida, Tampa, FL 33620, USA
| | - Yuan-Jhe Chang
- Department of Occupational Safety and Health, Chung Shan Medical University, Taichung 402, Taiwan
| | - Alexandra Keidel
- Oxidative Stress Group, Department of Molecular Biosciences, University of South Florida, Tampa, FL 33620, USA
| | - Mu-Rong Chao
- Department of Occupational Safety and Health, Chung Shan Medical University, Taichung 402, Taiwan; Department of Occupational Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan
| | - Chiung-Wen Hu
- Department of Public Health, Chung Shan Medical University, Taichung 402, Taiwan
| | - Marcus S Cooke
- Oxidative Stress Group, Department of Molecular Biosciences, University of South Florida, Tampa, FL 33620, USA; College of Public Health, University of South Florida, Tampa, FL 33620, USA; Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA.
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3
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Cheng X, An J, Lou J, Gu Q, Ding W, Droby GN, Wang Y, Wang C, Gao Y, Anand JR, Shelton A, Satterlee AB, Mann B, Hsiao YC, Liu CW, Lu K, Hingtgen S, Wang J, Liu Z, Miller CR, Wu D, Vaziri C, Yang Y. Trans-lesion synthesis and mismatch repair pathway crosstalk defines chemoresistance and hypermutation mechanisms in glioblastoma. Nat Commun 2024; 15:1957. [PMID: 38438348 PMCID: PMC10912752 DOI: 10.1038/s41467-024-45979-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 02/08/2024] [Indexed: 03/06/2024] Open
Abstract
Almost all Glioblastoma (GBM) are either intrinsically resistant to the chemotherapeutical drug temozolomide (TMZ) or acquire therapy-induced mutations that cause chemoresistance and recurrence. The genome maintenance mechanisms responsible for GBM chemoresistance and hypermutation are unknown. We show that the E3 ubiquitin ligase RAD18 (a proximal regulator of TLS) is activated in a Mismatch repair (MMR)-dependent manner in TMZ-treated GBM cells, promoting post-replicative gap-filling and survival. An unbiased CRISPR screen provides an aerial map of RAD18-interacting DNA damage response (DDR) pathways deployed by GBM to tolerate TMZ genotoxicity. Analysis of mutation signatures from TMZ-treated GBM reveals a role for RAD18 in error-free bypass of O6mG (the most toxic TMZ-induced lesion), and error-prone bypass of other TMZ-induced lesions. Our analyses of recurrent GBM patient samples establishes a correlation between low RAD18 expression and hypermutation. Taken together we define molecular underpinnings for the hallmark tumorigenic phenotypes of TMZ-treated GBM.
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Affiliation(s)
- Xing Cheng
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
- Department of Neuro-Oncology, Chongqing University Cancer Hospital, Chongqing, China
| | - Jing An
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
- Institute of Cancer Prevention and Treatment, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, China
| | - Jitong Lou
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC, 27599, USA
- Eli Lilly and Company, Indianapolis, IN, 46285, USA
| | - Qisheng Gu
- Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
- Department of Immunology, Université Paris Cité, Paris, France
| | - Weimin Ding
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA
- Oncology Center, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Gaith Nabil Droby
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Yilin Wang
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Chenghao Wang
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Yanzhe Gao
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Jay Ramanlal Anand
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Abigail Shelton
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Andrew Benson Satterlee
- Eshelman School of Pharmacy, Division of Pharmacoengineering and Molecular Pharmaceutics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Breanna Mann
- Eshelman School of Pharmacy, Division of Pharmacoengineering and Molecular Pharmaceutics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Yun-Chung Hsiao
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Chih-Wei Liu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Kun Lu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Shawn Hingtgen
- Eshelman School of Pharmacy, Division of Pharmacoengineering and Molecular Pharmaceutics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Jiguang Wang
- Division of Life Science, Department of Chemical and Biological Engineering, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- Hong Kong Center for Neurodegenerative Diseases, InnoHK, Hong Kong SAR, China
| | - Zhaoliang Liu
- Institute of Cancer Prevention and Treatment, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, China
| | - C Ryan Miller
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
- Department of Pathology, Division of Neuropathology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Di Wu
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC, 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA
- Division of Oral and Craniofacial Health Science, Adams School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Cyrus Vaziri
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA.
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA.
| | - Yang Yang
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA.
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA.
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4
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Cheng X, An J, Lou J, Gu Q, Ding W, Droby G, Wang Y, Wang C, Gao Y, Shelton A, Satterlee AB, Mann BE, Hsiao YC, Liu CW, Liu K, Hingtgen S, Wang J, Liu Z, Miller R, Wu D, Vaziri C, Yang Y. Trans-Lesion Synthesis and Mismatch Repair Pathway Crosstalk Defines Chemoresistance and Hypermutation Mechanisms in Glioblastoma. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.16.562506. [PMID: 37905107 PMCID: PMC10614844 DOI: 10.1101/2023.10.16.562506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Almost all Glioblastoma (GBM) are either intrinsically resistant to the chemotherapeutical drug temozolomide (TMZ) or acquire therapy-induced mutations that cause chemoresistance and recurrence. The genome maintenance mechanisms responsible for GBM chemoresistance and hypermutation are unknown. We show that the E3 ubiquitin ligase RAD18 (a proximal regulator of TLS) is activated in a Mismatch repair (MMR)-dependent manner in TMZ-treated GBM cells, promoting post-replicative gap-filling and survival. An unbiased CRISPR screen provides a new aerial map of RAD18-interacting DNA damage response (DDR) pathways deployed by GBM to tolerate TMZ genotoxicity. Analysis of mutation signatures from TMZ-treated GBM reveals a role for RAD18 in error-free bypass of O6mG (the most toxic TMZ-induced lesion), and error-prone bypass of other TMZ-induced lesions. Our analyses of recurrent GBM patient samples establishes a correlation between low RAD18 expression and hypermutation. Taken together we define novel molecular underpinnings for the hallmark tumorigenic phenotypes of TMZ-treated GBM.
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Affiliation(s)
- Xing Cheng
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Neuro-Oncology, Chongqing University Cancer Hospital & Chongqing Cancer Institute & Chongqing Cancer Hospital, Chongqing, China
| | - Jing An
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- Institute of Cancer Prevention and Treatment, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, China
| | - Jitong Lou
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Qisheng Gu
- Unit of Immunity and Pediatric Infectious Diseases, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- Department of Immunology, Université Paris Cité, Paris, France
| | - Weimin Ding
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Oncology Center, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Gaith Droby
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Yilin Wang
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Chenghao Wang
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Yanzhe Gao
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Abigail Shelton
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Andrew Benson Satterlee
- Eshelman School of Pharmacy, Division of Pharmacoengineering and Molecular Pharmaceutics, University of North Carolina, Chapel Hill, NC 27599
| | - Breanna Elizabeth Mann
- Eshelman School of Pharmacy, Division of Pharmacoengineering and Molecular Pharmaceutics, University of North Carolina, Chapel Hill, NC 27599
| | - Yun-Chung Hsiao
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Chih-Wei Liu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Kun Liu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Shawn Hingtgen
- Eshelman School of Pharmacy, Division of Pharmacoengineering and Molecular Pharmaceutics, University of North Carolina, Chapel Hill, NC 27599
| | - Jiguang Wang
- Division of Life Science, Department of Chemical and Biological Engineering, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- Hong Kong Center for Neurodegenerative Diseases, InnoHK, Hong Kong SAR, China
| | - Zhaoliang Liu
- Institute of Cancer Prevention and Treatment, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, China
| | - Ryan Miller
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Pathology, Division of Neuropathology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Di Wu
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Division of Oral and Craniofacial Health Science, Adams School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Cyrus Vaziri
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Yang Yang
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
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5
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Dorrell C, Peters AM, Zhang Q, Balaji N, Baradar K, Mochizuki-Kashio M, Major A, Finegold M, Liu CW, Lu K, Grompe M. Long-term combination therapy with Metformin and Oxymetholone in a Fanconi Anemia mouse model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.16.553572. [PMID: 37649908 PMCID: PMC10465065 DOI: 10.1101/2023.08.16.553572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Fanconi Anemia (FA) is a disease caused by defective DNA repair which manifests as bone marrow failure, cancer predisposition, and developmental defects. Mice containing inactivating mutations in one or more genes in the FA pathway partially mimic the human disease. We previously reported that monotherapy with either metformin (MET) or oxymetholone (OXM) improved peripheral blood (PB) counts and the number and functionality of bone marrow (BM) hematopoietic stem progenitor cells (HSPCs) number in Fancd2-/- mice. To evaluate whether the combination treatment of these drugs has a synergistic effect to prevent bone marrow failure in FA, we treated cohorts of Fancd2-/- mice and wild-type controls with either MET alone, OXM alone, MET+OXM or placebo diet. Both male and female mice were treated from age 3 weeks to 18 months. The OXM treated animals showed modest improvements in blood parameters including platelet count (p=0.01) and hemoglobin levels (p<0.05). In addition, the percentage of quiescent HSC (LSK) was significantly increased (p=0.001) by long-term treatment with MET alone. However, the absolute number of progenitors, measured by LSK frequency or CFU-S, was not significantly altered by MET therapy. The combination of metformin and oxymetholone did not result in a significant synergistic effect on any parameter. Male animals on MET+OXM or MET alone were significantly leaner than controls at 18 months, regardless of genotype. Gene expression analysis of liver tissue from these animals showed that some of the expression changes caused by Fancd2 deletion were partially normalized by metformin treatment. Importantly, no adverse effects of the individual or combination therapies were observed, despite the long-term administration.
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Affiliation(s)
- Craig Dorrell
- Department of Pediatrics, Papé Family Pediatric Research Institute, Pediatric Blood & Cancer Biology Program, Stem Cell Center; Oregon Health & Science University, Portland, OR
| | - Alexander M Peters
- Department of Pediatrics, Papé Family Pediatric Research Institute, Pediatric Blood & Cancer Biology Program, Stem Cell Center; Oregon Health & Science University, Portland, OR
| | - Qingshuo Zhang
- Department of Pediatrics, Papé Family Pediatric Research Institute, Pediatric Blood & Cancer Biology Program, Stem Cell Center; Oregon Health & Science University, Portland, OR
| | - Niveditha Balaji
- Department of Pediatrics, Papé Family Pediatric Research Institute, Pediatric Blood & Cancer Biology Program, Stem Cell Center; Oregon Health & Science University, Portland, OR
| | - Kevin Baradar
- Department of Pediatrics, Papé Family Pediatric Research Institute, Pediatric Blood & Cancer Biology Program, Stem Cell Center; Oregon Health & Science University, Portland, OR
| | - Makiko Mochizuki-Kashio
- Department of Pediatrics, Papé Family Pediatric Research Institute, Pediatric Blood & Cancer Biology Program, Stem Cell Center; Oregon Health & Science University, Portland, OR
| | - Angela Major
- Department of Pathology, Texas Children's Hospital, Houston, TX
| | - Milton Finegold
- Department of Pathology, Texas Children's Hospital, Houston, TX
| | - Chih-Wei Liu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Kun Lu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Markus Grompe
- Department of Pediatrics, Papé Family Pediatric Research Institute, Pediatric Blood & Cancer Biology Program, Stem Cell Center; Oregon Health & Science University, Portland, OR
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6
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Lu K, Hsiao YC, Liu CW, Schoeny R, Gentry R, Starr TB. A Review of Stable Isotope Labeling and Mass Spectrometry Methods to Distinguish Exogenous from Endogenous DNA Adducts and Improve Dose-Response Assessments. Chem Res Toxicol 2021; 35:7-29. [PMID: 34910474 DOI: 10.1021/acs.chemrestox.1c00212] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cancer remains the second most frequent cause of death in human populations worldwide, which has been reflected in the emphasis placed on management of risk from environmental chemicals considered to be potential human carcinogens. The formation of DNA adducts has been considered as one of the key events of cancer, and persistence and/or failure of repair of these adducts may lead to mutation, thus initiating cancer. Some chemical carcinogens can produce DNA adducts, and DNA adducts have been used as biomarkers of exposure. However, DNA adducts of various types are also produced endogenously in the course of normal metabolism. Since both endogenous physiological processes and exogenous exposure to xenobiotics can cause DNA adducts, the differentiation of the sources of DNA adducts can be highly informative for cancer risk assessment. This review summarizes a highly applicable methodology, termed stable isotope labeling and mass spectrometry (SILMS), that is superior to previous methods, as it not only provides absolute quantitation of DNA adducts but also differentiates the exogenous and endogenous origins of DNA adducts. SILMS uses stable isotope-labeled substances for exposure, followed by DNA adduct measurement with highly sensitive mass spectrometry. Herein, the utilities and advantage of SILMS have been demonstrated by the rich data sets generated over the last two decades in improving the risk assessment of chemicals with DNA adducts being induced by both endogenous and exogenous sources, such as formaldehyde, vinyl acetate, vinyl chloride, and ethylene oxide.
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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, United States
| | - Yun-Chung Hsiao
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Chih-Wei Liu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Rita Schoeny
- Rita Schoeny LLC, 726 Fifth Street NE, Washington, D.C. 20002, United States
| | - Robinan Gentry
- Ramboll US Consulting, Inc., Monroe, Louisiana 71201, United States
| | - Thomas B Starr
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.,TBS Associates, 7500 Rainwater Road, Raleigh, North Carolina 27615, United States
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7
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Hsiao YC, Liu CW, Hoffman G, Fang C, Lu K. Molecular Dosimetry of DNA Adducts in Rats Exposed to Vinyl Acetate Monomer. Toxicol Sci 2021; 185:197-207. [PMID: 34904679 PMCID: PMC8795904 DOI: 10.1093/toxsci/kfab140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Vinyl acetate monomer (VAM) is heavily used to synthesize polymers. Previous studies have shown that inhaled VAM, being metabolized to acetaldehyde, may form DNA adducts including N2-ethylidene-deoxyguanosine (N2-EtD-dG), which may subsequently cause mutations and contribute to its carcinogenesis. Currently, there is little knowledge on the molecular dosimetry between VAM exposure and DNA adducts under dosages relevant to human exposure. In this study, 0.02, 0.1, 1, 10, 50, 200, and 600 ppm VAM were exposed to rats by inhalation for 14 days (6 h/day). The use of [13C2]-VAM allows unambiguous differentiation and quantification of the exogenous and endogenous N2-EtD-dG by highly sensitive LC-MS/MS. Our data indicate that VAM-induced exogenous DNA adducts were formed in a non-linear manner. Exogenous DNA adducts were only detected in the nasal epithelium of rats exposed to 10, 50, 200, and 600 ppm VAM, whereas endogenous adducts were found in all nasal and other tissues analyzed. In addition, ratios of exogenous/endogenous DNA adducts were less than 1 with the dose up to 50 ppm, indicating that endogenous DNA adducts are predominant at low VAM concentrations. Moreover, differential dose-response in terms of exogenous DNA adduct formation were observed between nasal respiratory and olfactory epithelium. Furthermore, the lack of exogenous DNA adducts in distant tissues, including peripheral blood mononuclear cells, liver, brain, and bone marrow, indicates that VAM and/or its metabolite do not distribute systemically to cause DNA damage in distant tissues. Together, these results provided new molecular dosimetry to improve science-based cancer risk assessments of VAM.
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Affiliation(s)
- Yun-Chung Hsiao
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599, United States
| | - Chih-Wei Liu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599, United States
| | - Gary Hoffman
- Covance CRS, LLC, Somerset, New Jersey, 08873, United States
| | - Caroline Fang
- 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
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