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Wang Y, Le Y, Harris KL, Chen Y, Li X, Faske J, Wynne RA, Mittelstaedt RA, Cao X, Miranda-Colon J, Elkins L, Muskhelishvili L, Davis K, Mei N, Sun W, Robison TW, Heflich RH, Parsons BL. Repeat treatment of organotypic airway cultures with ethyl methanesulfonate causes accumulation of somatic cell mutations without expansion of bronchial-carcinoma-specific cancer driver mutations. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2024; 897:503786. [PMID: 39054009 DOI: 10.1016/j.mrgentox.2024.503786] [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: 03/06/2024] [Revised: 06/03/2024] [Accepted: 06/04/2024] [Indexed: 07/27/2024]
Abstract
The human in vitro organotypic air-liquid-interface (ALI) airway tissue model is structurally and functionally similar to the human large airway epithelium and, as a result, is being used increasingly for studying the toxicity of inhaled substances. Our previous research demonstrated that DNA damage and mutagenesis can be detected in human airway tissue models under conditions used to assess general and respiratory toxicity endpoints. Expanding upon our previous proof-of-principle study, human airway epithelial tissue models were treated with 6.25-100 µg/mL ethyl methanesulfonate (EMS) for 28 days, followed by a 28-day recovery period. Mutagenesis was evaluated by Duplex Sequencing (DS), and clonal expansion of bronchial-cancer-specific cancer-driver mutations (CDMs) was investigated by CarcSeq to determine if both mutation-based endpoints can be assessed in the same system. Additionally, DNA damage and tissue-specific responses were analyzed during the treatment and following the recovery period. EMS exposure led to time-dependent increases in mutagenesis over the 28-day treatment period, without expansion of clones containing CDMs; the mutation frequencies remained elevated following the recovery. EMS also produced an increase in DNA damage measured by the CometChip and MultiFlow assays and the elevated levels of DNA damage were reduced (but not eliminated) following the recovery period. Cytotoxicity and most tissue-function changes induced by EMS treatment recovered to control levels, the exception being reduced proliferating cell frequency. Our results indicate that general, respiratory-tissue-specific and genotoxicity endpoints increased with repeat EMS dosing; expansion of CDM clones, however, was not detected using this repeat treatment protocol. DISCLAIMER: This article reflects the views of its authors and does not necessarily reflect those of the U.S. Food and Drug Administration. Any mention of commercial products is for clarification only and is not intended as approval, endorsement, or recommendation.
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Affiliation(s)
- Yiying Wang
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA.
| | - Yuan Le
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Kelly L Harris
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Ying Chen
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Xilin Li
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Jennifer Faske
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Rebecca A Wynne
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Roberta A Mittelstaedt
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Xuefei Cao
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Jaime Miranda-Colon
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Lana Elkins
- Toxicologic Pathology Associates, Jefferson, AR 72079, USA
| | | | - Kelly Davis
- Toxicologic Pathology Associates, Jefferson, AR 72079, USA
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Wei Sun
- Division of Pharmacology/Toxicology for Immunology & Inflammation, Office of Immunology and Inflammation, Office of New Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Timothy W Robison
- Division of Pharmacology/Toxicology for Immunology & Inflammation, Office of Immunology and Inflammation, Office of New Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Robert H Heflich
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Barbara L Parsons
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
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Seo JE, Le Y, Revollo J, Miranda-Colon J, Xu H, McKinzie P, Mei N, Chen T, Heflich RH, Zhou T, Robison T, Bonzo JA, Guo X. Evaluating the mutagenicity of N-nitrosodimethylamine in 2D and 3D HepaRG cell cultures using error-corrected next generation sequencing. Arch Toxicol 2024; 98:1919-1935. [PMID: 38584193 PMCID: PMC11106104 DOI: 10.1007/s00204-024-03731-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Accepted: 03/07/2024] [Indexed: 04/09/2024]
Abstract
Human liver-derived metabolically competent HepaRG cells have been successfully employed in both two-dimensional (2D) and 3D spheroid formats for performing the comet assay and micronucleus (MN) assay. In the present study, we have investigated expanding the genotoxicity endpoints evaluated in HepaRG cells by detecting mutagenesis using two error-corrected next generation sequencing (ecNGS) technologies, Duplex Sequencing (DS) and High-Fidelity (HiFi) Sequencing. Both HepaRG 2D cells and 3D spheroids were exposed for 72 h to N-nitrosodimethylamine (NDMA), followed by an additional incubation for the fixation of induced mutations. NDMA-induced DNA damage, chromosomal damage, and mutagenesis were determined using the comet assay, MN assay, and ecNGS, respectively. The 72-h treatment with NDMA resulted in concentration-dependent increases in cytotoxicity, DNA damage, MN formation, and mutation frequency in both 2D and 3D cultures, with greater responses observed in the 3D spheroids compared to 2D cells. The mutational spectrum analysis showed that NDMA induced predominantly A:T → G:C transitions, along with a lower frequency of G:C → A:T transitions, and exhibited a different trinucleotide signature relative to the negative control. These results demonstrate that the HepaRG 2D cells and 3D spheroid models can be used for mutagenesis assessment using both DS and HiFi Sequencing, with the caveat that severe cytotoxic concentrations should be avoided when conducting DS. With further validation, the HepaRG 2D/3D system may become a powerful human-based metabolically competent platform for genotoxicity testing.
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Affiliation(s)
- Ji-Eun Seo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Yuan Le
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Javier Revollo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Jaime Miranda-Colon
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Hannah Xu
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Page McKinzie
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Tao Chen
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Robert H Heflich
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Tong Zhou
- Center for Veterinary Medicine, U.S. Food and Drug Administration, Rockville, MD, 20855, USA
| | - Timothy Robison
- Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Jessica A Bonzo
- Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA.
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Kopp B, Khawam A, Di Perna K, Lenart D, Vinette M, Silva R, Zanoni TB, Rore C, Guenigault G, Richardson E, Kostrzewski T, Boswell A, Van P, Valentine Iii C, Salk J, Hamel A. Liver-on-chip model and application in predictive genotoxicity and mutagenicity of drugs. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2024; 896:503762. [PMID: 38821675 DOI: 10.1016/j.mrgentox.2024.503762] [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: 12/01/2023] [Revised: 04/04/2024] [Accepted: 04/08/2024] [Indexed: 06/02/2024]
Abstract
Currently, there is no test system, whether in vitro or in vivo, capable of examining all endpoints required for genotoxicity evaluation used in pre-clinical drug safety assessment. The objective of this study was to develop a model which could assess all the required endpoints and possesses robust human metabolic activity, that could be used in a streamlined, animal-free manner. Liver-on-chip (LOC) models have intrinsic human metabolic activity that mimics the in vivo environment, making it a preferred test system. For our assay, the LOC was assembled using primary human hepatocytes or HepaRG cells, in a MPS-T12 plate, maintained under microfluidic flow conditions using the PhysioMimix® Microphysiological System (MPS), and co-cultured with human lymphoblastoid (TK6) cells in transwells. This system allows for interaction between two compartments and for the analysis of three different genotoxic endpoints, i.e. DNA strand breaks (comet assay) in hepatocytes, chromosome loss or damage (micronucleus assay) and mutation (Duplex Sequencing) in TK6 cells. Both compartments were treated at 0, 24 and 45 h with two direct genotoxicants: methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS), and two genotoxicants requiring metabolic activation: benzo[a]pyrene (B[a]P) and cyclophosphamide (CP). Assessment of cytochrome activity, RNA expression, albumin, urea and lactate dehydrogenase production, demonstrated functional metabolic capacities. Genotoxicity responses were observed for all endpoints with MMS and EMS. Increases in the micronucleus and mutations (MF) frequencies were also observed with CP, and %Tail DNA with B[a]P, indicating the metabolic competency of the test system. CP did not exhibit an increase in the %Tail DNA, which is in line with in vivo data. However, B[a]P did not exhibit an increase in the % micronucleus and MF, which might require an optimization of the test system. In conclusion, this proof-of-principle experiment suggests that LOC-MPS technology is a promising tool for in vitro hazard identification genotoxicants.
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Affiliation(s)
- B Kopp
- Charles River Laboratories Montreal ULC, Canada
| | - A Khawam
- Charles River Laboratories Montreal ULC, Canada
| | - K Di Perna
- Charles River Laboratories Montreal ULC, Canada
| | - D Lenart
- Charles River Laboratories Montreal ULC, Canada
| | - M Vinette
- Charles River Laboratories Montreal ULC, Canada
| | - R Silva
- CN Bio Innovations, Cambridge, United Kingdom
| | - T B Zanoni
- TwinStrand Biosciences, Seattle, United States
| | - C Rore
- CN Bio Innovations, Cambridge, United Kingdom
| | | | | | | | - A Boswell
- TwinStrand Biosciences, Seattle, United States
| | - P Van
- TwinStrand Biosciences, Seattle, United States
| | | | - J Salk
- TwinStrand Biosciences, Seattle, United States
| | - A Hamel
- Charles River Laboratories Montreal ULC, Canada.
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Andersson D, Kebede FT, Escobar M, Österlund T, Ståhlberg A. Principles of digital sequencing using unique molecular identifiers. Mol Aspects Med 2024; 96:101253. [PMID: 38367531 DOI: 10.1016/j.mam.2024.101253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/26/2024] [Accepted: 02/03/2024] [Indexed: 02/19/2024]
Abstract
Massively parallel sequencing technologies have long been used in both basic research and clinical routine. The recent introduction of digital sequencing has made previously challenging applications possible by significantly improving sensitivity and specificity to now allow detection of rare sequence variants, even at single molecule level. Digital sequencing utilizes unique molecular identifiers (UMIs) to minimize sequencing-induced errors and quantification biases. Here, we discuss the principles of UMIs and how they are used in digital sequencing. We outline the properties of different UMI types and the consequences of various UMI approaches in relation to experimental protocols and bioinformatics. Finally, we describe how digital sequencing can be applied in specific research fields, focusing on cancer management where it can be used in screening of asymptomatic individuals, diagnosis, treatment prediction, prognostication, monitoring treatment efficacy and early detection of treatment resistance as well as relapse.
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Affiliation(s)
- Daniel Andersson
- Sahlgrenska Center for Cancer Research, Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 413 90, Gothenburg, Sweden
| | - Firaol Tamiru Kebede
- Sahlgrenska Center for Cancer Research, Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 413 90, Gothenburg, Sweden
| | - Mandy Escobar
- Sahlgrenska Center for Cancer Research, Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 413 90, Gothenburg, Sweden
| | - Tobias Österlund
- Sahlgrenska Center for Cancer Research, Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 413 90, Gothenburg, Sweden; Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, 413 90, Gothenburg, Sweden; Department of Clinical Genetics and Genomics, Sahlgrenska University Hospital, 413 45, Gothenburg, Sweden
| | - Anders Ståhlberg
- Sahlgrenska Center for Cancer Research, Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 413 90, Gothenburg, Sweden; Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, 413 90, Gothenburg, Sweden; Department of Clinical Genetics and Genomics, Sahlgrenska University Hospital, 413 45, Gothenburg, Sweden.
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5
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Minko I, Luzadder M, Vartanian V, Rice SM, Nguyen M, Sanchez-Contreras M, Van P, Kennedy S, McCullough A, Lloyd R. Frequencies and spectra of aflatoxin B 1-induced mutations in liver genomes of NEIL1-deficient mice as revealed by duplex sequencing. NAR MOLECULAR MEDICINE 2024; 1:ugae006. [PMID: 38779538 PMCID: PMC11105970 DOI: 10.1093/narmme/ugae006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 04/18/2024] [Accepted: 05/16/2024] [Indexed: 05/25/2024]
Abstract
Increased risk for the development of hepatocellular carcinoma (HCC) is driven by a number of etiological factors including hepatitis viral infection and dietary exposures to foods contaminated with aflatoxin-producing molds. Intracellular metabolic activation of aflatoxin B1 (AFB1) to a reactive epoxide generates highly mutagenic AFB1-Fapy-dG adducts. Previously, we demonstrated that repair of AFB1-Fapy-dG adducts can be initiated by the DNA glycosylase NEIL1 and that male Neil1-/- mice were significantly more susceptible to AFB1-induced HCC relative to wild-type mice. To investigate the mechanisms underlying this enhanced carcinogenesis, WT and Neil1-/- mice were challenged with a single, 4 mg/kg dose of AFB1 and frequencies and spectra of mutations were analyzed in liver DNAs 2.5 months post-injection using duplex sequencing. The analyses of DNAs from AFB1-challenged mice revealed highly elevated mutation frequencies in the nuclear genomes of both males and females, but not the mitochondrial genomes. In both WT and Neil1-/- mice, mutation spectra were highly similar to the AFB1-specific COSMIC signature SBS24. Relative to wild-type, the NEIL1 deficiency increased AFB1-induced mutagenesis with concomitant elevated HCCs in male Neil1-/- mice. Our data establish a critical role of NEIL1 in limiting AFB1-induced mutagenesis and ultimately carcinogenesis.
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Affiliation(s)
- Irina G Minko
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
| | - Michael M Luzadder
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
| | - Vladimir L Vartanian
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
| | - Sean P M Rice
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
- School of Public Health, Oregon Health & Science University - Portland State University, Portland, OR, USA
| | - Megan M Nguyen
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | | | - Phu Van
- TwinStrand Biosciences, Inc., Seattle, WA, USA
| | - Scott R Kennedy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Amanda K McCullough
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, USA
| | - R Stephen Lloyd
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, USA
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6
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Sahib S, Yan J, Chen T. Application of duplex sequencing to evaluate mutagenicity of aristolochic acid and methapyrilene in Fisher 344 rats. Food Chem Toxicol 2024; 185:114512. [PMID: 38342231 DOI: 10.1016/j.fct.2024.114512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 02/07/2024] [Accepted: 02/08/2024] [Indexed: 02/13/2024]
Abstract
Duplex sequencing (DS) is an error-corrected next-generation sequencing (NGS) method that can overcome notorious high error rate from the process of NGS and detect ultralow-frequency mutations. In this study, we evaluated the mutagenicity of aristolochic acid, a known genotoxic carcinogen, and methapyrilene, a known nongenotoxic carcinogen using DS. Four male Fisher 344 rats were treated with aristolochic acid, methapyrilene, or the vehicle control for 6 weeks, liver tissues were collected one day after the treatment, and the DNA was isolated for analysis. The mutation frequency for the aristolochic acid-treated group was significantly increased over the vehicle control (44-fold), whereas no significant difference in the mutation frequency was observed between the methapyrilene-treated and the control groups. The primary type of mutation induced by aristolochic acid was A:T > T:A transversion, which occurred frequently at ApT sites, whereas the major type of mutation in the control and methapyrilene-treated groups was G:C > A:T transition, which occurred frequently at CpG sites. These findings are consistent with previously published data obtained with other in vivo mutation assays. Thus, our results suggest that the DS mutation assay is a promising technology for assessing mutagenicity of chemicals in vivo.
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Affiliation(s)
- Seaab Sahib
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Jian Yan
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Tao Chen
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA.
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7
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Marchetti F, Cardoso R, Chen CL, Douglas GR, Elloway J, Escobar PA, Harper T, Heflich RH, Kidd D, Lynch AM, Myers MB, Parsons BL, Salk JJ, Settivari RS, Smith-Roe SL, Witt KL, Yauk CL, Young R, Zhang S, Minocherhomji S. Error-corrected next generation sequencing - Promises and challenges for genotoxicity and cancer risk assessment. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2023; 792:108466. [PMID: 37643677 DOI: 10.1016/j.mrrev.2023.108466] [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: 03/09/2023] [Revised: 07/12/2023] [Accepted: 08/23/2023] [Indexed: 08/31/2023]
Abstract
Error-corrected Next Generation Sequencing (ecNGS) is rapidly emerging as a valuable, highly sensitive and accurate method for detecting and characterizing mutations in any cell type, tissue or organism from which DNA can be isolated. Recent mutagenicity and carcinogenicity studies have used ecNGS to quantify drug-/chemical-induced mutations and mutational spectra associated with cancer risk. ecNGS has potential applications in genotoxicity assessment as a new readout for traditional models, for mutagenesis studies in 3D organotypic cultures, and for detecting off-target effects of gene editing tools. Additionally, early data suggest that ecNGS can measure clonal expansion of mutations as a mechanism-agnostic early marker of carcinogenic potential and can evaluate mutational load directly in human biomonitoring studies. In this review, we discuss promising applications, challenges, limitations, and key data initiatives needed to enable regulatory testing and adoption of ecNGS - including for advancing safety assessment, augmenting weight-of-evidence for mutagenicity and carcinogenicity mechanisms, identifying early biomarkers of cancer risk, and managing human health risk from chemical exposures.
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Affiliation(s)
| | | | - Connie L Chen
- Health and Environmental Sciences Institute, Washington, DC, USA.
| | | | - Joanne Elloway
- Safety Sciences, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, Cambridge, UK
| | | | - Tod Harper
- Amgen Research, Amgen Inc, Thousand Oaks, CA, USA
| | - Robert H Heflich
- US Food and Drug Administration/National Center for Toxicological Research, Jefferson, AR, USA
| | - Darren Kidd
- Labcorp Early Development Laboratories Limited, Harrogate, North Yorkshire, UK
| | | | - Meagan B Myers
- US Food and Drug Administration/National Center for Toxicological Research, Jefferson, AR, USA
| | - Barbara L Parsons
- US Food and Drug Administration/National Center for Toxicological Research, Jefferson, AR, USA
| | | | | | | | - Kristine L Witt
- NIEHS, Division of the National Toxicology Program, Research Triangle Park, NC, USA
| | | | - Robert Young
- MilliporeSigma, Rockville, MD, USA; Current: Consultant, Bethesda, MD, USA
| | | | - Sheroy Minocherhomji
- Amgen Research, Amgen Inc, Thousand Oaks, CA, USA; Current: Eli Lilly and Company, Indianapolis, IN, USA
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