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Judice SA, Sussman HE, Walker DM, O'Neill JP, Albertini RJ, Walker VE. Clonality, trafficking, and molecular alterations among Hprt mutant T lymphocytes isolated from control mice versus mice treated with N-ethyl-N-nitrosourea. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2023; 64:432-457. [PMID: 37957787 PMCID: PMC10842105 DOI: 10.1002/em.22579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/03/2023] [Accepted: 11/10/2023] [Indexed: 11/15/2023]
Abstract
Mutations in T lymphocytes (T-cells) are informative quantitative markers for environmental mutagen exposures, but risk extrapolations from rodent models to humans also require an understanding of how T-cell development and proliferation kinetics impact mutagenic outcomes. Rodent studies have shown that patterns in chemical-induced mutations in the hypoxanthine-guanine phosphoribosyltransferase (Hprt) gene of T-cells differ between lymphoid organs. The current work was performed to obtain knowledge of the relationships between maturation events during T-cell development and changes in chemical-induced mutant frequencies over time in differing immune compartments of a mouse model. A novel reverse transcriptase-polymerase chain reaction based method was developed to determine the specific T-cell receptor beta (Tcrb) gene mRNA expressed in mouse T-cell isolates, enabling sequence analysis of the PCR product that then identifies the specific hypervariable CDR3 junctional region of the expressed Tcrb gene for individual isolates. Characterization of spontaneous Hprt mutant isolates from the thymus, spleen, and lymph nodes of control mice for their Tcrb gene expression found evidence of in vivo clonal amplifications of Hprt mutants and their trafficking between tissues in the same animal. Concurrent analyses of Hprt mutations and Tcrb gene rearrangements in different lymphoid tissues of control versus N-ethyl-N-nitrosourea-exposed mice permitted elucidation of the localization and timing of mutational events in T-cells, establishing that mutagenesis occurs primarily in the pre-rearrangement replicative period in pre-thymic/thymic populations. These findings demonstrate that chemical-induced mutagenic burden is determined by the combination of mutagenesis and T-cell clonal expansion, processes with roles in immune function and in the pathogenesis of autoimmune disease and cancer.
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Affiliation(s)
- Stephen A Judice
- Genetic Toxicology Laboratory, University of Vermont, Burlington, Vermont, USA
- EnviroLogix, Portland, Maine, USA
| | - Hillary E Sussman
- School of Public Health, University at Albany - SUNY, Albany, New York, USA
- New York State Department of Health, Wadsworth Center, Albany, New York, USA
- Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, USA
| | - Dale M Walker
- Experimental Pathology Laboratories, Sterling, Virginia, USA
- The Burlington HC Research group, Inc., Jericho, Vermont, USA
| | - J Patrick O'Neill
- Genetic Toxicology Laboratory, University of Vermont, Burlington, Vermont, USA
| | - Richard J Albertini
- Genetic Toxicology Laboratory, University of Vermont, Burlington, Vermont, USA
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Vernon E Walker
- New York State Department of Health, Wadsworth Center, Albany, New York, USA
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
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Yu P, Lian Y, Zuleger CL, Albertini RJ, Albertini MR, Newton MA. SURROGATE SELECTION OVERSAMPLES EXPANDED T CELL CLONOTYPES. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.13.548950. [PMID: 37503118 PMCID: PMC10369934 DOI: 10.1101/2023.07.13.548950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Inference from immunological data on cells in the adaptive immune system may benefit from modeling specifications that describe variation in the sizes of various clonal sub-populations. We develop one such specification in order to quantify the effects of surrogate selection assays, which we confirm may lead to an enrichment for amplified, potentially disease-relevant T cell clones. Our specification couples within-clonotype birth-death processes with an exchangeable model across clonotypes. Beyond enrichment questions about the surrogate selection design, our framework enables a study of sampling properties of elementary sample diversity statistics; it also points to new statistics that may usefully measure the burden of somatic genomic alterations associated with clonal expansion. We examine statistical properties of immunological samples governed by the coupled model specification, and we illustrate calculations in surrogate selection studies of melanoma and in single-cell genomic studies of T cell repertoires.
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Affiliation(s)
- Peng Yu
- Department of Statistics, University of Wisconsin, Madison
| | - Yumin Lian
- Department of Chemistry, Laboratory of Genetics, University of Wisconsin, Madison
| | - Cindy L. Zuleger
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison
- Carbone Cancer Center, University of Wisconsin, Madison
| | | | - Mark R. Albertini
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison
- Carbone Cancer Center, University of Wisconsin, Madison
- Medical Service, William S. Middleton Memorial Veterans Hospital, Madison
| | - Michael A. Newton
- Department of Statistics, University of Wisconsin, Madison
- Carbone Cancer Center, University of Wisconsin, Madison
- Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison
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3
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Maslov AY, Makhortov S, Sun S, Heid J, Dong X, Lee M, Vijg J. Single-molecule, quantitative detection of low-abundance somatic mutations by high-throughput sequencing. SCIENCE ADVANCES 2022; 8:eabm3259. [PMID: 35394831 PMCID: PMC8993124 DOI: 10.1126/sciadv.abm3259] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 02/18/2022] [Indexed: 06/14/2023]
Abstract
Postzygotic somatic mutations have been found associated with human disease, including diseases other than cancer. Most information on somatic mutations has come from studying clonally amplified mutant cells, based on a growth advantage or genetic drift. However, almost all somatic mutations are unique for each cell, and the quantitative analysis of these low-abundance mutations in normal tissues remains a major challenge in biology. Here, we introduce single-molecule mutation sequencing (SMM-seq), a novel approach for quantitative identification of point mutations in normal cells and tissues.
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Affiliation(s)
- Alexander Y. Maslov
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Laboratory of Applied Genomic Technologies, Voronezh State University of Engineering Technologies, Voronezh, Russia
| | - Sergey Makhortov
- Department of Programming and Information Technology, Voronezh State University, Voronezh, Russia
| | - Shixiang Sun
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Johanna Heid
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Xiao Dong
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Institute on the Biology of Aging and Metabolism and Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Moonsook Lee
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Jan Vijg
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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4
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Molecular characterization of hypoxanthine guanine phosphoribosyltransferase mutant T cells in human blood: The concept of surrogate selection for immunologically relevant cells. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2022; 789:108414. [PMID: 35690417 PMCID: PMC9188651 DOI: 10.1016/j.mrrev.2022.108414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 03/01/2022] [Accepted: 03/08/2022] [Indexed: 11/23/2022]
Abstract
Somatic cell gene mutations arise in vivo due to replication errors during DNA synthesis occurring spontaneously during normal DNA synthesis or as a result of replication on a DNA template damaged by endogenous or exogenous mutagens. In principle, changes in the frequencies of mutant cells in vivo in humans reflect changes in exposures to exogenous or endogenous DNA damaging insults, other factors being equal. It is becoming increasingly evident however, that somatic mutations in humans have a far greater range of interpretations. For example, mutations in lymphocytes provide invaluable probes for in vivo cellular and molecular processes, providing identification of clonal amplifications of these cells in autoimmune and infectious diseases, transplantation recipients, paroxysmal nocturnal hemoglobinuria (PNH), and cancer. The assay for mutations of the X-chromosomal hypoxanthine guanine phosphoribosyltransferase (HPRT) gene has gained popular acceptance for this purpose since viable mutant cells can be recovered for molecular and other analyses. Although the major application of the HPRT T cell assay remains human population monitoring, the enrichment of activated T cells in the mutant fraction in individuals with ongoing immunological processes has demonstrated the utility of surrogate selection, a method that uses somatic mutation as a surrogate marker for the in vivo T cell proliferation that underlies immunological processes to investigate clinical disorders with immunological features. Studies encompassing a wide range of clinical conditions are reviewed. Despite the historical importance of the HPRT mutation system in validating surrogate selection, there are now additional mutational and other methods for identifying immunologically active T cells. These methods are reviewed and provide insights for strategies to extend surrogate selection in future studies.
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Somatic Mutations and Autoimmunity. Cells 2021; 10:cells10082056. [PMID: 34440825 PMCID: PMC8394445 DOI: 10.3390/cells10082056] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 11/17/2022] Open
Abstract
Autoimmune diseases are among the most common chronic illness caused by a dysregulated immune response against self-antigens. Close to 5% of the general population in Western countries develops some form of autoimmunity, yet its underlying causes, although intensively studied, are still not fully known, and no curative therapies exist. It is well established that autoimmune diseases have common mechanisms and are caused by both genetic and non-genetic risk factors. One novel risk factor that can contribute to autoimmunity is somatic mutations, in a role parallel to their role in cancer. Somatic mutations are stochastic, de novo, non-inherited mutations. In this hypothesis, the persistent proliferation of self-reactive lymphocytes (that is usually hindered by a series of checkpoints) is permitted, due to somatic mutations in these expanding cells, allowing them to bypass multiple regulatory checkpoints, causing autoimmunity. This novel concept of the contribution of these mutations in non-malignant diseases has recently started to be explored. It proposes a novel paradigm for autoimmunity etiology and could be the missing piece of the autoimmunity puzzle.
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Ware RE, Dertinger SD. Absence of hydroxyurea-induced mutational effects supports higher utilisation for the treatment of sickle cell anaemia. Br J Haematol 2021; 194:252-266. [PMID: 33570176 DOI: 10.1111/bjh.17323] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 12/21/2020] [Indexed: 12/21/2022]
Abstract
Hydroxyurea (hydroxycarbamide) is approved for treating both children and adults with sickle cell anaemia (SCA). Fetal haemoglobin (HbF) induction is the primary treatment response, along with improved anaemia, reduced haemolysis, myelosuppression and decreased endothelial inflammation. Hydroxyurea has proven clinical efficacy for SCA - treatment significantly reduces disease manifestations and prolongs survival. Despite these recognised benefits, long-standing concerns regarding the risks of mutagenic and potentially carcinogenic drug exposure have hampered efforts for broad hydroxyurea use in SCA, although these are based largely on outdated experimental models and treatment experiences with myeloproliferative neoplasms. Consequently, many patients with SCA are not receiving this highly effective disease-modifying therapy. In this review, we describe the concept of genotoxicity and its laboratory measurements, summarise hydroxyurea-associated data from both preclinical and clinical studies, and discuss carcinogenic potential. The genotoxicity results clearly demonstrate that hydroxyurea does not directly bind DNA and is not mutagenic. Rather, its genotoxic effects are limited to indirect clastogenicity occurring in select cell types, and only when high dose and time thresholds are exceeded. This absence of mutagenic activity is consistent with the observed lack of any compelling carcinogenic potential. Since hydroxyurea therapy for SCA carries minimal carcinogenic risks, the current drug labelling should be modified accordingly, and prescribing practices should be broadened to allow better access and increased utilisation of this highly effective drug.
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Affiliation(s)
- Russell E Ware
- Division of Hematology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.,Global Health Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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Vimercati L, Bisceglia L, Cavone D, Caputi A, De Maria L, Delfino MC, Corrado V, Ferri GM. Environmental Monitoring of PAHs Exposure, Biomarkers and Vital Status in Coke Oven Workers. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17072199. [PMID: 32218300 PMCID: PMC7178092 DOI: 10.3390/ijerph17072199] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/11/2020] [Accepted: 03/20/2020] [Indexed: 12/14/2022]
Abstract
A follow-up study of a cohort of workers from a coke plant compared with a control group from the same industrial area was conducted in 2019. The recruitment and environmental and biomarker measurements were performed during 1993/1994. The environmental concentrations of polycyclic aromatic hydrocarbons (PAH), B(a)P, pyrene and nitro-PAH were measured. Personal data were collected via an individual semi-structured questionnaire by a trained physician. All biomarkers were measured after a specific blood drawing for every test. Significant risks (ORs) were observed for nitro-PAH (≥0.12 µg/m3) [OR = 7.96 (1.01–62.82)], urinary 1-hydroxypyrene (1-OHpy) (≥0.99 µmoles/moles of creatinine) [OR = 11.71 (1.47–92.90)], PAH DNA adducts (P32) (≥2.69 adducts/108 nucleotides) [OR = 5.46 (1.17–25.58)], total nitro-PAH hemoglobin adducts (≥161.68 fg/µg of Hb) [OR = 5.92 (1.26–27.86)], sister chromatid exchange (SCE) with TCR (≥377.84 SCE/cell chromosomes) [OR = 13.06 (3.95–93.10)], sister chromatid exchange with T (≥394.72 total SCE) [OR = 13.06 (3.95–93.10)], and sister chromatid exchange with X (≥8.19 mean SCE) [OR = 13.06 (3.95–93.10)]. Significant risk of death for all causes and chromosomal aberrations (48 h) (OR = 7.19 [1.19–43.44]) or micronuclei in culture at 48 h (OR = 3.86 [1.04–14.38]) were also found.
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Affiliation(s)
- Luigi Vimercati
- Interdisciplinary Department of Medicine, Occupational Medicine “B. Ramazzini”, University of Bari Medical School, 11 G. Cesare Square, 70124 Bari, Italy; (D.C.); (A.C.); (L.D.M.); (M.C.D.); (V.C.); (G.M.F.)
- Correspondence: ; Tel.: +39-080-547-8216
| | - Lucia Bisceglia
- Strategic Regional Health and Social Agency of Puglia (AReS Puglia), 52 G. Gentile Street, 70126 Bari, Italy;
| | - Domenica Cavone
- Interdisciplinary Department of Medicine, Occupational Medicine “B. Ramazzini”, University of Bari Medical School, 11 G. Cesare Square, 70124 Bari, Italy; (D.C.); (A.C.); (L.D.M.); (M.C.D.); (V.C.); (G.M.F.)
| | - Antonio Caputi
- Interdisciplinary Department of Medicine, Occupational Medicine “B. Ramazzini”, University of Bari Medical School, 11 G. Cesare Square, 70124 Bari, Italy; (D.C.); (A.C.); (L.D.M.); (M.C.D.); (V.C.); (G.M.F.)
| | - Luigi De Maria
- Interdisciplinary Department of Medicine, Occupational Medicine “B. Ramazzini”, University of Bari Medical School, 11 G. Cesare Square, 70124 Bari, Italy; (D.C.); (A.C.); (L.D.M.); (M.C.D.); (V.C.); (G.M.F.)
| | - Maria Celeste Delfino
- Interdisciplinary Department of Medicine, Occupational Medicine “B. Ramazzini”, University of Bari Medical School, 11 G. Cesare Square, 70124 Bari, Italy; (D.C.); (A.C.); (L.D.M.); (M.C.D.); (V.C.); (G.M.F.)
| | - Vincenzo Corrado
- Interdisciplinary Department of Medicine, Occupational Medicine “B. Ramazzini”, University of Bari Medical School, 11 G. Cesare Square, 70124 Bari, Italy; (D.C.); (A.C.); (L.D.M.); (M.C.D.); (V.C.); (G.M.F.)
| | - Giovanni Maria Ferri
- Interdisciplinary Department of Medicine, Occupational Medicine “B. Ramazzini”, University of Bari Medical School, 11 G. Cesare Square, 70124 Bari, Italy; (D.C.); (A.C.); (L.D.M.); (M.C.D.); (V.C.); (G.M.F.)
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8
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Molecular Analysis of Mutations in the Human HPRT Gene. Methods Mol Biol 2020. [PMID: 31989566 DOI: 10.1007/978-1-0716-0223-2_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The HPRT assay uses incorporation of toxic nucleotide analogues to select for cells lacking the purine scavenger enzyme hypoxanthine-guanine phosphoribosyl transferase. A major advantage of this assay is the ability to isolate mutant cells and determine the molecular basis for their functional deficiency. Many types of analyses have been performed at this locus: the current protocol involves generation of a cDNA and multiplex PCR of each exon, including the intron/exon junctions, followed by direct sequencing of the products. This analysis detects point mutations, small deletions and insertions within the gene, mutations affecting RNA splicing, and the products of illegitimate V(D)J recombination within the gene. Establishment of and comparisons with mutational spectra hold the promise of identifying exposures to mutation-inducing genotoxicants from their distinctive pattern of gene-specific DNA damage at this easily analyzed reporter gene.
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Analysis of In Vivo Mutation in the Hprt and Tk Genes of Mouse Lymphocytes. Methods Mol Biol 2020. [PMID: 31989565 DOI: 10.1007/978-1-0716-0223-2_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Determining mutant frequencies in endogenous reporter genes is a tool for identifying potentially genotoxic environmental agents, and discovering phenotypes prone to genomic instability and diseases, such as cancer. Here, we describe a high-throughput method for identifying mouse spleen lymphocytes with mutations in the endogenous X-linked hypoxanthine guanine phosphoribosyl transferase (Hprt) gene and the endogenous autosomal thymidine kinase (Tk) gene. The selective clonal expansion of mutant lymphocytes is based upon the phenotypic properties of HPRT- and TK-deficient cells. The same procedure can be utilized for quantifying Hprt mutations in most strains of mice (and, with minor changes, in other mammalian species), while mutations in the Tk gene can be determined only in transgenic mice that are heterozygous for inactivation of this gene. Expanded mutant clones can be further analyzed to classify the types of mutations in the Tk gene (small intragenic mutations vs. large chromosomal mutations) and to determine the nature of intragenic mutation at both the Hprt and Tk genes.
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Van Horebeek L, Dubois B, Goris A. Somatic Variants: New Kids on the Block in Human Immunogenetics. Trends Genet 2019; 35:935-947. [PMID: 31668909 DOI: 10.1016/j.tig.2019.09.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/23/2019] [Accepted: 09/27/2019] [Indexed: 01/21/2023]
Abstract
Somatic variants are not inherited but acquired during an individual's lifetime, and individuals are increasingly considered as complex mosaics of genetically distinct cells. Whereas this concept is long-recognized in cancer, this review focuses on the growing role of somatic variants in immune cells in nonmalignant immune-related disorders, such as primary immunodeficiency and autoimmune diseases. Older case reports described somatic variants early in development, leading to large numbers of affected cells and severe phenotypes. Thanks to technological evolution, it is now feasible to detect somatic variants occurring later in life and affecting fewer cells. Hence, only recently is the scale at which somatic variants contribute to monogenic diseases being uncovered and is their contribution to complex diseases being explored systematically.
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Affiliation(s)
- L Van Horebeek
- KU Leuven Department of Neurosciences, Laboratory for Neuroimmunology, 3000 Leuven, Belgium; Leuven Brain Institute, 3000 Leuven, Belgium
| | - B Dubois
- KU Leuven Department of Neurosciences, Laboratory for Neuroimmunology, 3000 Leuven, Belgium; Leuven Brain Institute, 3000 Leuven, Belgium; University Hospitals Leuven, Department of Neurology, 3000 Leuven, Belgium
| | - A Goris
- KU Leuven Department of Neurosciences, Laboratory for Neuroimmunology, 3000 Leuven, Belgium; Leuven Brain Institute, 3000 Leuven, Belgium.
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Nimker S, Sharma K, Saraswathy R, Chandna S. Delineating the Effects of Ionizing Radiation on Erythropoietic Lineage-Implications for Radiation Biodosimetry. HEALTH PHYSICS 2019; 116:677-693. [PMID: 30720544 DOI: 10.1097/hp.0000000000000975] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The overall lethality/morbidity of ionizing radiation exposure involves multiple forms of inhibitory or cytotoxic effects that may manifest in different tissues with a varying dose and time response. One of the major systemic effects leading to lethality of radiation includes its suppressive effect on hematopoiesis, which could be observed even at doses as low as 1-2 Gy, whereas effects on gastrointestinal and nervous systems appear at relatively higher doses in the same order. This article reviews the effects of radiation on the three distinct stages of erythropoiesis-formation of erythroid progenitor cells, differentiation of erythroid precursor cells, and terminal maturation. During these stepwise developmental processes, erythroid progenitor cells undergo rapid expansion to form terminally differentiated red blood cells that are continuously replenished from bone marrow into the circulating peripheral blood stream. Cellular radiation response depends upon many factors such as cell lineage, rate of proliferation, and differentiation status. Therefore, we discuss radiation-induced alterations during the progenitor, precursor, and terminal maturation stages and the implications thereof. Since biomarkers of ionizing radiation exposure in human populations are of great interest for assessing normal tissue injury as well as for biodosimetry in the event of accidental or incidental radiation exposures, we also highlight blood-based biomarkers that have potential utility for medical management.
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Affiliation(s)
- Shwetanjali Nimker
- Division of Natural Radiation Response Mechanisms, Institute of Nuclear Medicine and Allied Sciences, Timarpur, Delhi, India
- School of Biosciences and Technology, Vellore Institiute of Technology, Vellore, Tamil Nadu, India
| | - Kanupriya Sharma
- Division of Natural Radiation Response Mechanisms, Institute of Nuclear Medicine and Allied Sciences, Timarpur, Delhi, India
| | - Radha Saraswathy
- School of Biosciences and Technology, Vellore Institiute of Technology, Vellore, Tamil Nadu, India
| | - Sudhir Chandna
- Division of Natural Radiation Response Mechanisms, Institute of Nuclear Medicine and Allied Sciences, Timarpur, Delhi, India
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Abstract
DNA mutations as a consequence of errors during DNA damage repair, replication, or mitosis are the substrate for evolution. In multicellular organisms, mutations can occur in the germline and also in somatic tissues, where they are associated with cancer and other chronic diseases and possibly with aging. Recent advances in high-throughput sequencing have made it relatively easy to study germline de novo mutations, but in somatic cells, the vast majority of mutations are low-abundant and can be detected only in clonal lineages, such as tumors, or single cells. Here we review recent results on somatic mutations in normal human and animal tissues with a focus on their possible functional consequences.
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Affiliation(s)
- Lei Zhang
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461, USA;
| | - Jan Vijg
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461, USA;
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Townsend MH, Robison RA, O'Neill KL. A review of HPRT and its emerging role in cancer. Med Oncol 2018; 35:89. [PMID: 29730818 DOI: 10.1007/s12032-018-1144-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 04/21/2018] [Indexed: 11/25/2022]
Abstract
Hypoxanthine guanine phosphoribosyltransferase (HPRT) is a common salvage housekeeping gene with a historically important role in cancer as a mutational biomarker. As an established and well-known human reporter gene for the evaluation of mutational frequency corresponding to cancer development, HPRT is most commonly used to evaluate cancer risk within individuals and determine potential carcinogens. In addition to its use as a reporter gene, HPRT also has important functionality in the body in relation to purine regulation as demonstrated by Lesch-Nyhan patients whose lack of functional HPRT leads to significant purine overproduction and further neural complications. This regulatory role, in addition to an established connection between other salvage enzymes and cancer development, points to HPRT as an emerging influence in cancer. Recent work has shown that not only is the enzyme upregulated within malignant tumors, it also has significant surface localization within some cancer cells. With this is mind, HPRT has the potential to become a significant biomarker not only for the characterization of cancer, but also for its potential treatment.
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Affiliation(s)
- Michelle H Townsend
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
| | - Richard A Robison
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
| | - Kim L O'Neill
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA.
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14
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Genome instability: a conserved mechanism of ageing? Essays Biochem 2017; 61:305-315. [PMID: 28550046 DOI: 10.1042/ebc20160082] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/18/2017] [Accepted: 05/02/2017] [Indexed: 01/09/2023]
Abstract
DNA is the carrier of genetic information and the primary template from which all cellular information is ultimately derived. Changes in the DNA information content through mutation generate diversity for evolution through natural selection but are also a source of deleterious effects. It has since long been hypothesized that mutation accumulation in somatic cells of multicellular organisms could causally contribute to age-related cellular degeneration and death. Assays to detect different types of mutations, from base substitutions to large chromosomal aberrations, have been developed and show unequivocally that mutations accumulate in different tissues and cell types of ageing humans and animals. More recently, next-generation sequencing-based methods have been developed to accurately determine the complete landscape of base substitution mutations in single cells. The first results show that the somatic mutation rate is much higher than the germline mutation rate and that base substitution loads in somatic cells are high enough to potentially affect cellular function.
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15
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Vijg J, Dong X, Zhang L. A high-fidelity method for genomic sequencing of single somatic cells reveals a very high mutational burden. Exp Biol Med (Maywood) 2017; 242:1318-1324. [PMID: 28737476 PMCID: PMC5529006 DOI: 10.1177/1535370217717696] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Postzygotic mutations in somatic cells lead to genome mosaicism and can be the cause of cancer, possibly other human diseases and aging. Somatic mutations are difficult to detect in bulk tissue samples. Here, we review the available assays for measuring somatic mutations, with a focus on recent single-cell, whole genome sequencing methods. Impact statement Somatic mutations cause cancer, possibly other diseases and aging. Yet, very little is known about the frequency of such mutations in vivo, their distribution across the genome, and their possible functional consequences other than cancer. Even in cancer, we do not know the heterogeneity of mutations within a tumor and if seemingly normal cells in its surroundings already have elevated mutation frequencies. Here, we review a new, whole genome amplification system that allows accurate quantification and characterization of single-cell mutational landscapes in human cells and tissues in relation to disease.
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Affiliation(s)
- Jan Vijg
- Department of Genetics, Albert Einstein College of Medicine, Michael F. Price Center, Bronx, NY 10461, USA
| | - Xiao Dong
- Department of Genetics, Albert Einstein College of Medicine, Michael F. Price Center, Bronx, NY 10461, USA
| | - Lei Zhang
- Department of Genetics, Albert Einstein College of Medicine, Michael F. Price Center, Bronx, NY 10461, USA
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Valori M, Jansson L, Kiviharju A, Ellonen P, Rajala H, Awad SA, Mustjoki S, Tienari PJ. A novel class of somatic mutations in blood detected preferentially in CD8+ cells. Clin Immunol 2016; 175:75-81. [PMID: 27932211 PMCID: PMC5341785 DOI: 10.1016/j.clim.2016.11.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 12/31/2022]
Abstract
Somatic mutations have a central role in cancer but their role in other diseases such as autoimmune disorders is poorly understood. Earlier work has provided indirect evidence of rare somatic mutations in autoreactive T-lymphocytes in multiple sclerosis (MS) patients but such mutations have not been identified thus far. We analysed somatic mutations in blood in 16 patients with relapsing MS and 4 with other neurological autoimmune disease. To facilitate the detection of somatic mutations CD4+, CD8+, CD19+ and CD4-/CD8-/CD19- cell subpopulations were separated. We performed next-generation DNA sequencing targeting 986 immune-related genes. Somatic mutations were called by comparing the sequence data of each cell subpopulation to other subpopulations of the same patient and validated by amplicon sequencing. We found non-synonymous somatic mutations in 12 (60%) patients (10 MS, 1 myasthenia gravis, 1 narcolepsy). There were 27 mutations, all different and mostly novel (67%). They were discovered at subpopulation-wise allelic fractions of 0.2%-4.6% (median 0.95%). Multiple mutations were found in 8 patients. The mutations were enriched in CD8+ cells (85% of mutations). In follow-up after a median time of 2.3years, 96% of the mutations were still detectable. These results unravel a novel class of persistent somatic mutations, many of which were in genes that may play a role in autoimmunity (ATM, BTK, CD46, CD180, CLIP2, HMMR, IKFZF3, ITGB3, KIR3DL2, MAPK10, CD56/NCAM1, RBM6, RORA, RPA1 and STAT3). Whether some of this class of mutations plays a role in disease is currently unclear, but these results define an interesting hitherto unknown research target for future studies.
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Affiliation(s)
- Miko Valori
- Molecular Neurology, Research Programs Unit, University of Helsinki, Department of Neurology, Helsinki University Hospital, Haartmaninkatu 8, FIN-00290 Helsinki, Finland.
| | - Lilja Jansson
- Molecular Neurology, Research Programs Unit, University of Helsinki, Department of Neurology, Helsinki University Hospital, Haartmaninkatu 8, FIN-00290 Helsinki, Finland.
| | - Anna Kiviharju
- Molecular Neurology, Research Programs Unit, University of Helsinki, Department of Neurology, Helsinki University Hospital, Haartmaninkatu 8, FIN-00290 Helsinki, Finland.
| | - Pekka Ellonen
- Finnish Institute for Molecular Medicine (FIMM), University of Helsinki, Helsinki, Finland.
| | - Hanna Rajala
- Hematology Research Unit Helsinki, University of Helsinki and Helsinki University Hospital Comprehensive Cancer Center, Haartmaninkatu 8, FIN-00029 Helsinki, Finland.
| | - Shady Adnan Awad
- Hematology Research Unit Helsinki, University of Helsinki and Helsinki University Hospital Comprehensive Cancer Center, Haartmaninkatu 8, FIN-00029 Helsinki, Finland; Department of Clinical Chemistry, University of Helsinki, Helsinki, Finland.
| | - Satu Mustjoki
- Hematology Research Unit Helsinki, University of Helsinki and Helsinki University Hospital Comprehensive Cancer Center, Haartmaninkatu 8, FIN-00029 Helsinki, Finland; Department of Clinical Chemistry, University of Helsinki, Helsinki, Finland.
| | - Pentti J Tienari
- Molecular Neurology, Research Programs Unit, University of Helsinki, Department of Neurology, Helsinki University Hospital, Haartmaninkatu 8, FIN-00290 Helsinki, Finland.
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17
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Simultaneous determination of 6-mercaptopruine, 6-thioguanine and dasatinib as three important anticancer drugs using nanostructure voltammetric sensor employing Pt/MWCNTs and 1-butyl-3-methylimidazolium hexafluoro phosphate. Biosens Bioelectron 2016; 86:879-884. [DOI: 10.1016/j.bios.2016.07.086] [Citation(s) in RCA: 207] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 07/23/2016] [Accepted: 07/25/2016] [Indexed: 11/22/2022]
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18
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Analysis of in vivo mutation in the Hprt and Tk genes of mouse lymphocytes. Methods Mol Biol 2014; 1105:255-70. [PMID: 24623234 DOI: 10.1007/978-1-62703-739-6_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Assays measuring mutant frequencies in endogenous reporter genes are used for identifying potentially genotoxic environmental agents and discovering phenotypes prone to genomic instability and diseases, such as cancer. Here, we describe methods for identifying mouse spleen lymphocytes with mutations in the endogenous X-linked hypoxanthine guanine phosphoribosyl transferase (Hprt) gene and the endogenous autosomal thymidine kinase (Tk) gene. The selective clonal expansion of mutant lymphocytes is based upon the phenotypic properties of HPRT- and TK-deficient cells. The same procedure can be utilized for quantifying Hprt mutations in most strains of mice (and, with minor changes, in other mammalian species), while mutations in the Tk gene can be determined only in transgenic mice that are heterozygous for inactivation of this gene. Expanded mutant clones can be further analyzed to classify the types of mutations in the Tk gene (small intragenic mutations vs. large chromosomal mutations) and to determine the nature of intragenic mutation in both the Hprt and Tk genes.
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19
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Girardi C, De Pittà C, Casara S, Calura E, Romualdi C, Celotti L, Mognato M. Integration analysis of microRNA and mRNA expression profiles in human peripheral blood lymphocytes cultured in modeled microgravity. BIOMED RESEARCH INTERNATIONAL 2014; 2014:296747. [PMID: 25045661 PMCID: PMC4090438 DOI: 10.1155/2014/296747] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 05/22/2014] [Accepted: 05/22/2014] [Indexed: 01/07/2023]
Abstract
We analyzed miRNA and mRNA expression profiles in human peripheral blood lymphocytes (PBLs) incubated in microgravity condition, simulated by a ground-based rotating wall vessel (RWV) bioreactor. Our results show that 42 miRNAs were differentially expressed in MMG-incubated PBLs compared with 1 g incubated ones. Among these, miR-9-5p, miR-9-3p, miR-155-5p, miR-150-3p, and miR-378-3p were the most dysregulated. To improve the detection of functional miRNA-mRNA pairs, we performed gene expression profiles on the same samples assayed for miRNA profiling and we integrated miRNA and mRNA expression data. The functional classification of miRNA-correlated genes evidenced significant enrichment in the biological processes of immune/inflammatory response, signal transduction, regulation of response to stress, regulation of programmed cell death, and regulation of cell proliferation. We identified the correlation of miR-9-3p, miR-155-5p, miR-150-3p, and miR-378-3p expression with that of genes involved in immune/inflammatory response (e.g., IFNG and IL17F), apoptosis (e.g., PDCD4 and PTEN), and cell proliferation (e.g., NKX3-1 and GADD45A). Experimental assays of cell viability and apoptosis induction validated the results obtained by bioinformatics analyses demonstrating that in human PBLs the exposure to reduced gravitational force increases the frequency of apoptosis and decreases cell proliferation.
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Affiliation(s)
- C. Girardi
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35131 Padova, Italy
| | - C. De Pittà
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35131 Padova, Italy
| | - S. Casara
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35131 Padova, Italy
| | - E. Calura
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35131 Padova, Italy
| | - C. Romualdi
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35131 Padova, Italy
| | - L. Celotti
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35131 Padova, Italy
- Laboratori Nazionali di Legnaro, INFN, Viale dell'Università 2, Legnaro, 35020 Padova, Italy
| | - M. Mognato
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35131 Padova, Italy
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20
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Myers NT, Grant SG. The blood-based glycophorin A (GPA) human in vivo somatic mutation assay. Methods Mol Biol 2014; 1105:223-244. [PMID: 24623232 DOI: 10.1007/978-1-62703-739-6_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The glycophorin A assay concurrently detects and quantifies erythrocytes with allele-loss phenotypes at the autosomal locus responsible for the polymorphic MN blood group. It uses a pair of allele-specific monoclonal antibodies and flow cytometry to efficiently analyze a standard population of five million cells. Two distinct variant phenotypes are detected: simple allele loss and allele loss followed by reduplication of the remaining allele; both are consistent with the mechanisms underlying "loss of heterozygosity" at tumor-suppressor genes. The assay is an intermediate biomarker of biological effect in the somatic mutational model of human cancer and has been applied to populations with a known or suspected genotoxic exposure, to patients with hereditary syndromes causing predisposition to cancer (where the assay has been applied diagnostically), and to patients manifesting cancer as a disease endpoint.
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Affiliation(s)
- Nicole T Myers
- Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, FL, USA
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21
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Niu Y, Zhang X, Zheng Y, Zhang R. XRCC1 deficiency increased the DNA damage induced by γ-ray in HepG2 cell: Involvement of DSB repair and cell cycle arrest. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2013; 36:311-319. [PMID: 23708312 DOI: 10.1016/j.etap.2013.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 04/17/2013] [Accepted: 04/18/2013] [Indexed: 06/02/2023]
Abstract
γ-ray irradiation can induce DNA damages which include base damages, single-strand breaks and double-strand breaks in various type cells. The DNA repair protein XRCC1, as a part of the BER pathway, forms complexes with DNA polymerase beta, DNA ligase III and poly-ADP-ribose polymerase (PARP) in the repair of DNA single strand breaks and also affects the repair of double strand breaks. However, it is still not known well whether XRCC1 contributes to affect the irradiation sensitivity and DNA damage in HepG2 cell and the potential mechanism. Hence, the purpose of this study was to explore whether abrogation of XRCC1 gene expression by shRNA could reduce DNA repair and thus sensitize HepG2 cells to γ-ray. Cell viability was measured by Trypan blue staining and cloning efficiency assay. The DNA damage was detected by Comet assay. Apoptosis and cell cycle were detected by flow cytometry. The DNA-PKcs and gadd153 mRNA expression were determined by Real-time PCR. Our results showed that abrogation of XRCC 1 could sensitize HepG2 cells to γ-ray. This enhanced sensitivity could be attributed to the increased DNA damage and increased cell cycle arrest, which might be related with the increasing of DNA-PKcs and gadd153 mRNA expression. Therefore, our results suggested that the γ-ray irradiation sensitivity could be increased by targeting inhibition of XRCC1 in HepG2 cell.
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Affiliation(s)
- Yujie Niu
- Department of Toxicology, School of Public Health, Hebei Medical University, 361 Zhongshan East Road, Shijiazhuang 050017, Hebei, People's Republic of China; Department of Occupational and Environmental Health, School of Public Health, Hebei Medical University, 361 Zhongshan East Road, Shijiazhuang 050017, Hebei, People's Republic of China
| | - Xing Zhang
- National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, 29 Nanwei Road, Xuanwu District, Beijing 100050, People's Republic of China
| | - Yuxin Zheng
- National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, 29 Nanwei Road, Xuanwu District, Beijing 100050, People's Republic of China
| | - Rong Zhang
- Department of Toxicology, School of Public Health, Hebei Medical University, 361 Zhongshan East Road, Shijiazhuang 050017, Hebei, People's Republic of China.
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22
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The rate of spontaneous mutations in human myeloid cells. Mutat Res 2013; 749:49-57. [PMID: 23748046 DOI: 10.1016/j.mrfmmm.2013.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 05/28/2013] [Accepted: 05/29/2013] [Indexed: 01/09/2023]
Abstract
The mutation rate (μ) is likely to be a key parameter in leukemogenesis, but historically, it has been difficult to measure in humans. The PIG-A gene has some advantages for the detection of spontaneous mutations because it is X-linked, and therefore only one mutation is required to disrupt its function. Furthermore, the PIG-A-null phenotype is readily detected by flow cytometry. Using PIG-A, we have now provided the first in vitro measurement of μ in myeloid cells, using cultures of CD34+ cells that are transduced with either the AML-ETO or the MLL-AF9 fusion genes and expanded with cytokines. For the AML-ETO cultures, the median μ value was ∼9.4×10(-7) (range ∼3.6-23×10(-7)) per cell division. In contrast, few spontaneous mutations were observed in the MLL-AF9 cultures. Knockdown of p53 or introduction of mutant NRAS or FLT3 alleles did not have much of an effect on μ. Based on these data, we provide a model to predict whether hypermutability must occur in the process of leukemogenesis.
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23
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Walker DM, Patrick O'Neill J, Tyson FL, Walker VE. The stress response resolution assay. I. Quantitative assessment of environmental agent/condition effects on cellular stress resolution outcomes in epithelium. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2013; 54:268-280. [PMID: 23554083 DOI: 10.1002/em.21772] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 02/11/2013] [Accepted: 02/14/2013] [Indexed: 06/02/2023]
Abstract
The events or factors that lead from normal cell function to conditions and diseases such as aging or cancer reflect complex interactions between cells and their environment. Cellular stress responses, a group of processes involved in homeostasis and adaptation to environmental change, contribute to cell survival under stress and can be resolved with damage avoidance or damage tolerance outcomes. To investigate the impact of environmental agents/conditions upon cellular stress response outcomes in epithelium, a novel quantitative assay, the "stress response resolution" (SRR) assay, was developed. The SRR assay consists of pretreatment with a test agent or vehicle followed later by a calibrated stress conditions exposure step (here, using 6-thioguanine). Pilot studies conducted with a spontaneously-immortalized murine mammary epithelial cell line pretreated with vehicle or 20 µg N-ethyl-N-nitrososurea/ml medium for 1 hr, or two hTERT-immortalized human bronchial epithelial cell lines pretreated with vehicle or 100 µM zidovudine/lamivudine for 12 days, found minimal alterations in cell morphology, survival, or cell function through 2 weeks post-exposure. However, when these pretreatments were followed 2 weeks later by exposure to calibrated stress conditions of limited duration (for 4 days), significant alterations in stress resolution were observed in pretreated cells compared with vehicle-treated control cells, with decreased damage avoidance survival outcomes in all cell lines and increased damage tolerance outcomes in two of three cell lines. These pilot study results suggest that sub-cytotoxic pretreatments with chemical mutagens have long-term adverse impact upon the ability of cells to resolve subsequent exposure to environmental stressors.
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Affiliation(s)
- Dale M Walker
- Experimental Pathology Laboratories, Inc., Herndon, VA, USA
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24
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Zanesi N, Ferraro P, Pavanello S, Furlan D, Celotti L. Cytotoxic and mutagenic effects of anti- and syn-benzo[a]pyrene diol epoxide in human lymphocytes. Toxicol In Vitro 2012; 8:1269-75. [PMID: 20693099 DOI: 10.1016/0887-2333(94)90120-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/1994] [Revised: 05/24/1994] [Indexed: 10/27/2022]
Abstract
Cytotoxicity and mutagenicity were measured in human lymphocytes after treatment in vitro with anti- or syn-benzo[a]pyrene diolepoxide, two diastereoisomer metabolites of benzo[a]pyrene. These compounds were incubated with resting and cycling lymphocytes to determine the inhibition of cell proliferation induced by phytohemoagglutinin and interleukin2 at different times after treatment. Anti-benzo[a]pyrene diolepoxide was more cytotoxic than the syn-adduct under all conditions, and its effect on cell growth was more marked in cycling lymphocytes. In contrast, neither of the compounds induced alteration of the ATP intracellular pool. Cytotoxic effects of anti- and syn-benzo[a]pyrene diolepoxide were also assessed by determining the cloning efficiency. Both compounds affected the cloning efficiency in human lymphocytes and the effect of anti-benzo[a]pyrene was particularly marked. Mutagenic potency of anti- and syn-benzo[a]pyrene diolepoxide at the hgprt locus was measured both in the V79 cell line and in human lymphocytes by selection of mutant cells in medium containing 6-thioguanine. Both compounds increased the mutant frequency in comparison with the control and anti-benzo[a]pyrene diolepoxide was more active than the syn-metabolite.
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Affiliation(s)
- N Zanesi
- Department of Biology, via Trieste 75, 35121 Padova, Italy
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25
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Araten DJ, Sanders KJ, Anscher D, Zamechek L, Hunger SP, Ibrahim S. Leukemic blasts with the paroxysmal nocturnal hemoglobinuria phenotype in children with acute lymphoblastic leukemia. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:1862-9. [PMID: 22940070 DOI: 10.1016/j.ajpath.2012.07.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/21/2012] [Accepted: 07/05/2012] [Indexed: 01/12/2023]
Abstract
It has been proposed that genomic instability is essential to account for the multiplicity of mutations often seen in malignancies. Using the X-linked PIG-A gene as a sentinel gene for spontaneous inactivating somatic mutations, we previously showed that healthy individuals harbor granulocytes with the PIG-A mutant (paroxysmal nocturnal hemoglobinuria) phenotype at a median frequency (f) of ∼12 × 10(-6). Herein, we used a similar approach to determine f in blast cells derived from 19 individuals with acute lymphoblastic leukemia (ALL) and in immortalized Epstein-Barr virus-transformed B-cell cultures (human B-lymphoblastoid cell lines) from 19 healthy donors. The B-lymphoblastoid cell lines exhibited a unimodal distribution, with a median f value of 11 × 10(-6). In contrast, analysis of the f values for the ALL samples revealed at least two distinct populations: one population, representing approximately half of the samples (n = 10), had a median f value of 13 × 10(-6), and the remaining samples (n = 9) had a median f value of 566 × 10(-6). We conclude that in ALL, there are two distinct phenotypes with respect to hypermutability, which we hypothesize will correlate with the number of pathogenic mutations required to produce the leukemia.
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Affiliation(s)
- David J Araten
- Division of Hematology, New York University School of Medicine, New York University Langone Clinical Cancer Center, New York, USA.
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26
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Zhang X, Lou Z, Wang A, Zhang H. Detection of Wild-Type Hypoxanthine Guanine Phosphoribosyl Transferase of Lymphocytes in Gamma-Irradiated Mice with Surface Plasmon Resonance. ANAL LETT 2012. [DOI: 10.1080/00032719.2012.655677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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27
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Guo D, Gao A, Michels DA, Feeney L, Eng M, Chan B, Laird MW, Zhang B, Yu XC, Joly J, Snedecor B, Shen A. Mechanisms of unintended amino acid sequence changes in recombinant monoclonal antibodies expressed in Chinese Hamster Ovary (CHO) cells. Biotechnol Bioeng 2010; 107:163-71. [DOI: 10.1002/bit.22780] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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28
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Araten DJ, Sanders KJ, Pu J, Lee S. Spontaneously arising red cells with a McLeod-like phenotype in normal donors. Mutat Res 2009; 671:1-5. [PMID: 19909712 DOI: 10.1016/j.mrfmmm.2009.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 03/05/2009] [Accepted: 03/24/2009] [Indexed: 11/26/2022]
Abstract
Very few human genes can be used to identify spontaneous inactivating somatic mutations. We hypothesized that because the XK gene is X-linked, it would be easy to identify spontaneously arising red cells with a phenotype resembling the McLeod syndrome, which results from inherited XK mutations. Here, by flow cytometry, we detect such phenotypic variants at a median frequency of 9 x 10(-6) in neonatal cord blood samples and 39 x 10(-6) in healthy adults (p=0.004). It may be possible to further investigate the relationship between aging, mutations, and cancer using this approach.
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Affiliation(s)
- David J Araten
- Division of Hematology, Department of Medicine, NYU School of Medicine, New York, NY, United States.
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29
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Dobrovolsky VN, Shaddock JG, Mittelstaedt RA, Manjanatha MG, Miura D, Uchikawa M, Mattison DR, Morris SM. Evaluation of Macaca mulatta as a model for genotoxicity studies. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2009; 673:21-8. [DOI: 10.1016/j.mrgentox.2008.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 11/06/2008] [Accepted: 11/10/2008] [Indexed: 10/21/2022]
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30
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Sudo H, Li-Sucholeiki XC, Marcelino LA, Gruhl AN, Herrero-Jimenez P, Zarbl H, Willey JC, Furth EE, Morgenthaler S, Coller HA, Ekstrom PO, Kurzweil R, Gostjeva EV, Thilly WG. Fetal-juvenile origins of point mutations in the adult human tracheal-bronchial epithelium: absence of detectable effects of age, gender or smoking status. Mutat Res 2008; 646:25-40. [PMID: 18824180 DOI: 10.1016/j.mrfmmm.2008.08.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 08/21/2008] [Accepted: 08/29/2008] [Indexed: 11/19/2022]
Abstract
Allele-specific mismatch amplification mutation assays (MAMA) of anatomically distinct sectors of the upper bronchial tracts of nine nonsmokers revealed many numerically dispersed clusters of the point mutations C742T, G746T, G747T of the TP53 gene, G35T of the KRAS gene and G508A of the HPRT1 gene. Assays of these five mutations in six smokers have yielded quantitatively similar results. One hundred and eighty four micro-anatomical sectors of 0.5-6x10(6) tracheal-bronchial epithelial cells represented en toto the equivalent of approximately 1.7 human smokers' bronchial trees to the fifth bifurcation. Statistically significant mutant copy numbers above the 95% upper confidence limits of historical background controls were found in 198 of 425 sector assays. No significant differences (P=0.1) for negative sector fractions, mutant fractions, distributions of mutant cluster size or anatomical positions were observed for smoking status, gender or age (38-76 year). Based on the modal cluster size of mitochondrial point mutants, the size of the adult bronchial epithelial maintenance turnover unit was estimated to be about 32 cells. When data from all 15 lungs were combined the log2 of nuclear mutant cluster size plotted against log2 of the number of clusters of a given cluster size displayed a slope of approximately 1.1 over a range of cluster sizes from approximately 2(6) to 2(15) mutant copies. A parsimonious interpretation of these nuclear and previously reported data for lung epithelial mitochondrial point mutant clusters is that they arose from mutations in stem cells at a high but constant rate per stem cell doubling during at least ten stem cell doublings of the later fetal-juvenile period. The upper and lower decile range of summed point mutant fractions among lungs was about 7.5-fold, suggesting an important source of stratification in the population with regard to risk of tumor initiation.
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Affiliation(s)
- Hiroko Sudo
- Massachusetts Institute of Technology, Department of Biological Engineering, 21 Ames St., 16-743 Cambridge, MA 02139, United States
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31
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Jones IM, Burkhart-Schultz K, Strout CL, Nelson DO. Studies of thioguanine-resistant lymphocytes induced by in vivo irradiation of mice. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:343-350. [PMID: 18418873 DOI: 10.1002/em.20388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The frequency of Hprt-deficient lymphocytes in mice after in vivo gamma irradiation, has been found to vary as a function of time elapsed after exposure and irradiation dose. The frequency of mutant lymphocytes in spleen was determined using an in vitro, clonogenic assay for thioguanine-resistant T-lymphocytes. Mice were exposed to single doses of 0-400 cGy from cesium-137 or to eight daily doses of 50 cGy. The time to maximum-induced mutant frequency was 3 weeks. The dose response was strikingly curvilinear at 3-5 weeks after irradiation, but less precisely defined for 10-53 weeks after exposure, being fit by either linear or quadratic dependence. Three weeks after eight daily 50 cGy exposures, mutant frequency was elevated above controls and mice exposed to 50 cGy (which were not distinct from the nonirradiated controls), but only 17% in that of mice given a single 400 cGy fraction. This fractionation effect and the curvilinearity of the early dose-response curve suggested that saturation of repair increased the yield of mutations at higher acute doses. The decline of spleen mutant frequency in mice observed between 5 and 10 weeks after irradiation may reflect selection against some mutants. The marked variation of mutant frequency, as a function of time after irradiation and of dose rate, emphasize the need to evaluate these variables carefully and consistently in future studies.
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Affiliation(s)
- Irene M Jones
- Chemistry, Materials, Earth and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California, USA.
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32
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Grifalconi M, Celotti L, Mognato M. Bystander response in human lymphoblastoid TK6 cells. Mutat Res 2007; 625:102-11. [PMID: 17669438 DOI: 10.1016/j.mrfmmm.2007.06.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 05/23/2007] [Accepted: 06/01/2007] [Indexed: 05/16/2023]
Abstract
The mechanisms of the medium-mediated bystander response induced by gamma-rays in non-irradiated TK6 cells were investigated. Cell cultures were irradiated and the culture medium discarded immediately after irradiation and replaced with a fresh one. In cells incubated with conditioned medium from irradiated cells (CM), a significant decrease in cell viability and cloning efficiency was observed, together with a significant increase in apoptosis, also in directly irradiated cells. To examine whether bystander apoptosis involved the extrinsic pathway, an inhibitor of caspase-8 was added to CM cultures, which significantly decreased apoptosis to control levels. The addition to CM of ROS scavengers, Cu-Zn superoxide dismutase and N-acetylcysteine did not affect the induction of apoptosis. To assess whether CM treatment activates a DNA damage response, also the formation of gamma-H2AX foci, as markers of double-strand breaks and their colocalisation with 53-binding protein 1 (53BP1) and the protein mutated in the Nijmegen breakage syndrome 1 (NBS1) was analysed. In cultures treated for 2h with CM, 9-11% of cells showed gamma-H2AX foci, which partially or totally lacked colocalisation with 53BP1 and NBS1 foci. About 85% of irradiated cells were positive for gamma-H2AX foci, which colocalised with 53BP1 and NBS1 proteins. At 24h from irradiation, very few irradiated cells retained foci, fitting DNA repair kinetics. The number of foci-positive bystander cells also decreased to background values 24h after CM incubation. Our results suggest that irradiated TK6 cells release into the medium some soluble factors, not ROS, which are responsible for the cytotoxic effects induced in bystander cells. In our experimental system, the role of ROS appeared to be of minor importance in inducing cell mortality, but probably critical in activating the DNA damage response in the responsive fraction of bystander cells.
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Affiliation(s)
- Mauro Grifalconi
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy
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Jianhua Z, Lian X, Shuanlai Z, Juan D, Shuanxi Y. DNA Lesion and
Hprt
Mutant Frequency in Rat Lymphocytes and V79 Chinese Hamster Lung Cells Exposed to Cadmium. J Occup Health 2006; 48:93-9. [PMID: 16612037 DOI: 10.1539/joh.48.93] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Cadmium is a potential carcinogenic environmental and occupational pollutant. A wide variety of mutagens have been shown to cause DNA damage, but it is not yet clear whether the DNA damage is relative to inducement of mutations. DNA damage and the formation of mutations at the hypoxanthine guanine phosphoribosyl trans ferase (HPRT) induced by cadmium chloride (CdCl(2)) were investigated with rat lymphocytes and V79 Chinese hamster lung cells. The hprt mutant frequency (MF) assay was used as the method to measure gene mutation in the rat lymphocytes and V79 cells exposed to CdCl(2), and comet assay analysis was performed to detect DNA lesion and repair in CdCl(2)-induced V79 cells. The results showed that CdCl(2) treatment caused a strong genotoxic effect and a marginal effect on the frequency of gene mutations. The hprt mutant frequencies in the rat lymphocytes and V79 cells exposed to CdCl(2) were statistically higher than those of the negative control. There was statistical significance in TL, TD and percentage of comet cell with tails. CdCl(2) treatment can induce DNA single-strand breaks. There was a dose-dependent increase between CdCl(2) and DNA lesion. After cells were treated with CdCl(2) and hydrogen peroxide (H(2)O(2)), the TL and TD declined with repair time increasing, which indicated that DNA damages were repaired gradually. However, DNA repair with treatment of CdCl(2) was slower than that of H(2)O(2) in V79 cells, which suggests that CdCl(2) affected DNA repair of damaged cells. The study also showed that the hprt MF and comet assay can be used for genotoxicity testing of heavy metals. DNA damage detected with the comet assay may be relative to mutagenesis.
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Affiliation(s)
- Zhou Jianhua
- Department of Occupational and Environmental Health, School of Radiation Medicine and Public Health, Soochow University, Suzhou, China
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Sudo H, Li-Sucholeiki XC, Marcelino LA, Gruhl AN, Zarbl H, Willey JC, Thilly WG. Distributions of five common point mutants in the human tracheal-bronchial epithelium. Mutat Res 2006; 596:113-27. [PMID: 16458330 DOI: 10.1016/j.mrfmmm.2005.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Revised: 12/21/2005] [Accepted: 12/22/2005] [Indexed: 11/20/2022]
Abstract
The mutations C742T, G746T, G747T in the TP53 gene and G35T in the KRAS gene have been repeatedly found in sectors of human tumors by direct DNA sequencing. The mutation G508A in the HPRT1 gene has been repeatedly found among peripheral T lymphocytes by clonal expansion under selective conditions. To discover if these mutations also occur frequently in normal tissues from which tumors arise, we have developed and validated allele-specific mismatch amplification mutation assays (MAMA) for each mutation. Reconstruction experiments demonstrated linearity in the range of 9-3000 mutant alleles among 3 x 10(6) wild-type alleles. The cumulative distributions of all negative controls established robust detection limits (P<0.05) of 34-125 mutants per 10(6) copies assayed depending on the mutation. One hundred and seventy-seven micro-anatomical samples of approximately (0.5-6)x10(6) tracheal-bronchial epithelial cells from nine non-smokers were assayed representing en toto the equivalent of approximately 1.6 human bronchial trees to the fifth bifurcation. Statistically significant mutant copy numbers were found in 257 of 463 assays. Clusters of mutant copies ranged from 10 to 1000 in 239/257 positive samples. As all five point mutations were detected at mutant fractions of >10(-5) in two or more lungs, we infer that they are mutational hotspots generated in lung epithelial stem cells. As the cancer-associated mutations did not differ in cluster size distribution from the HPRT1 mutation, we infer that none of the mutations conferred a growth advantage to somatic heterozygous clusters or maintenance turnover units. Specific mutants appeared in very large copy numbers, 1000-35,000, in 18/257 positive assays. Various hypotheses to account for the observed cluster size distributions are offered.
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Affiliation(s)
- Hiroko Sudo
- Massachusetts Institute of Technology, 77 Massachusetts Ave., Bldg. 16-743 Cambridge, MA 02139, USA
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O'Neill P, Nicklas J, Hirsch B, Jostes R, Hunter T, Sullivan L, Albertini R. In vitro studies of the genotoxicity of ionizing radiation in human G(0) T lymphocytes. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2005; 46:207-20. [PMID: 15887213 DOI: 10.1002/em.20143] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
In an effort to mimic human in vivo exposures to ionizing irradiation, G(0) phase T lymphocytes from human peripheral blood samples were utilized for in vitro studies of the genotoxic effects of (137)Cs low-LET irradiation and (222)Rn high-LET irradiation. Both types of radiation induced mutations in the HPRT gene in a dose-dependent manner, with a mutant frequency (MF) = 4.28 + 1.34x + 7.51x(2) for (137)Cs (R(2) = 0.95) and MF = 4.81 + 0.67x for (222)Rn (R(2) = 0.51). Post (137)Cs irradiation incubation in the presence of cytosine arabinoside, a reversible inhibitor of DNA repair, caused an increase in the MF over irradiation alone, consistent with a misrepair mechanism being involved in the mutagenicity of low-LET irradiation. The spectrum of (137)Cs irradiation-induced mutation displayed an increase in macro-deletions (in particular total gene deletions) and rearrangement events, some of which were further defined by either chromosome painting or direct DNA sequencing. The spectrum of (222)Rn irradiation-induced mutation was characterized by an increase in small alterations, especially multiple single base deletions/substitutions and micro-deletions. These studies define the specific response of human peripheral blood T cells to ionizing irradiation in vitro and form a basis for evaluating the genotoxic effects of human in vivo exposure.
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Affiliation(s)
- Patrick O'Neill
- University of Vermont, Genetics Laboratory, Burlington, VT 05405, USA.
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Araten DJ, Golde DW, Zhang RH, Thaler HT, Gargiulo L, Notaro R, Luzzatto L. A quantitative measurement of the human somatic mutation rate. Cancer Res 2005; 65:8111-7. [PMID: 16166284 DOI: 10.1158/0008-5472.can-04-1198] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The mutation rate (mu) is a key biological feature of somatic cells that determines risk for malignant transformation, and it has been exceedingly difficult to measure in human cells. For this purpose, a potential sentinel is the X-linked PIG-A gene, because its inactivation causes lack of glycosylphosphatidylinositol-linked membrane proteins. We previously found that the frequency (f) of PIG-A mutant cells can be measured accurately by flow cytometry, even when f is very low. Here we measure both f and mu by culturing B-lymphoblastoid cell lines and first eliminating preexisting PIG-A mutants by flow sorting. After expansion in culture, the frequency of new mutants is determined by flow cytometry using antibodies specific for glycosylphosphatidylinositol-linked proteins (e.g., CD48, CD55, and CD59). The mutation rate is then calculated by the formula mu = f/d, where d is the number of cell divisions occurring in culture. The mean mu in cells from normal donors was 10.6 x 10(-7) mutations per cell division (range 2.4 to 29.6 x 10(-7)). The mean mu was elevated >30-fold in cells from patients with Fanconi anemia (P < 0.0001), and mu varied widely in ataxia-telangiectasia with a mean 4-fold elevation (P = 0.002). In contrast, mu was not significantly different from normal in cells from patients with Nijmegen breakage syndrome. Differences in mu could not be attributed to variations in plating efficiency. The mutation rate in man can now be measured routinely in B-lymphoblastoid cell lines, and it is elevated in cancer predisposition syndromes. This system should be useful in evaluating cancer risk and in the design of preventive strategies.
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Affiliation(s)
- David J Araten
- Division of Hematology, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
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Vacek PM, Messier T, Rivers J, Sullivan L, O'Neill JP, Finette BA. Somatic mutant frequency at the HPRT locus in children associated with a pediatric cancer cluster linked to exposure to two superfund sites. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2005; 45:339-345. [PMID: 15657919 DOI: 10.1002/em.20101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The somatic mutant frequency (Mf) of the hypoxanthine phosphoribosyl transferase (HPRT) gene has been widely used as a biomarker for the genotoxic effects of exposure but few studies have found an association with environmental exposures. We measured background Mfs in 49 current and former residents of Dover Township, New Jersey, who were exposed during childhood to industrially contaminated drinking water. The exposed subjects were the siblings of children who developed cancer after residing in Dover Township, where the incidence of childhood cancer has been elevated since 1979. Mfs from this exposed group were compared to Mfs in 43 age-matched, presumably unexposed residents of neighboring communities with no known water contamination and no increased cancer incidence. Statistical comparisons were based on the natural logarithm of Mf (lnMF). The mean Mf for the exposed group did not differ significantly from the unexposed group (3.90 x 10(-6) vs. 5.06 x 10(-6); P = 0.135), but unselected cloning efficiencies were higher in the exposed group (0.55 vs. 0.45; P = 0.005). After adjustment for cloning efficiency, lnMf values were very similar in both groups and age-related increases were comparable to those previously observed in healthy children. The results suggest that HPRT Mf may not be a sensitive biomarker for the genotoxic effects of environmental exposures in children, particularly when substantial time has elapsed since exposure.
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Affiliation(s)
- Pamela M Vacek
- Department of Medical Biostatistics, University of Vermont, Burlington, Vermont 05405, USA.
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Canova S, Fiorasi F, Mognato M, Grifalconi M, Reddi E, Russo A, Celotti L. "Modeled microgravity" affects cell response to ionizing radiation and increases genomic damage. Radiat Res 2005; 163:191-9. [PMID: 15658895 DOI: 10.1667/rr3304] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this work was to assess whether "modeled microgravity" affects cell response to ionizing radiation, increasing the risk associated with radiation exposure. Lymphoblastoid TK6 cells were irradiated with various doses of gamma rays and incubated for 24 h in a modeled microgravity environment obtained by the Rotating Wall Vessel bioreactor. Cell survival, induction of apoptosis and cell cycle alteration were compared in cells irradiated and then incubated in 1g or modeled microgravity conditions. Modulation of genomic damage induced by ionizing radiation was evaluated on the basis of HPRT mutant frequency and the micronucleus assay. A significant reduction in apoptotic cells was observed in cells incubated in modeled microgravity after gamma irradiation compared with cells maintained in 1g. Moreover, in irradiated cells, fewer G2-phase cells were found in modeled microgravity than in 1g, whereas more G1-phase cells were observed in modeled microgravity than in 1g. Genomic damage induced by ionizing radiation, i.e. frequency of HPRT mutants and micronucleated cells, increased more in cultures incubated in modeled microgravity than in 1g. Our results indicate that modeled microgravity incubation after irradiation affects cell response to ionizing radiation, reducing the level of radiation-induced apoptosis. As a consequence, modeled microgravity increases the frequency of damaged cells that survive after irradiation.
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Affiliation(s)
- Sabrina Canova
- Dipartimento di Biologia, Università di Padova, 35121 Padova, Italy
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Kumar PRV, Hamza VZ, Mohankumar MN, Jeevanram RK. Studies on the HPRT mutant frequency in T lymphocytes from healthy Indian male population as a function of age and smoking. Mutat Res 2004; 556:107-16. [PMID: 15491638 DOI: 10.1016/j.mrfmmm.2004.07.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2004] [Revised: 07/06/2004] [Accepted: 07/14/2004] [Indexed: 11/23/2022]
Abstract
Mutant frequency at the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene in the peripheral blood lymphocytes obtained from 44 healthy individuals (23 non-smokers and 21 smokers) of an Indian male population was studied using T-lymphocyte cloning assay. It was found that lnMF increased with age at a rate of 2.5% per year (P <0.001). Blood samples from smokers showed a significant (P <0.037) increase in HPRT mutant frequency (MF) (10.43 +/- 4.74 x 10(-6)) as compared to that obtained from non-smokers (7.69 +/- 3.69 x 10(-6)). This study also showed a significant (P <0.027) inverse correlation between lnMF and non-selected cloning efficiency (CE). However, with respect to age no variation was observed in cloning efficiency. The results obtained in this study showed a good comparison with those reported in different populations of the world.
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Affiliation(s)
- P R Vivek Kumar
- Radiological Safety Division, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam-603102, India
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40
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Duan J, Nilsson L, Lambert B. Structural and functional analysis of mutations at the human hypoxanthine phosphoribosyl transferase (HPRT1) locus. Hum Mutat 2004; 23:599-611. [PMID: 15146465 DOI: 10.1002/humu.20047] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hypoxanthine phosphoribosyl transferase (HPRT, also known as HGPRT) is an often-used genetic marker in eukaryotic cells. The gene is conserved from bacteria to human, with retained catalytic activity, although substrate specificity may have changed, and the enzyme is essential in malaria-causing protozoans. Inherited mutations in the human HPRT1 gene result in three different phenotypes: Lesch-Nyhan syndrome (LNS or LND), LND variants, and HPRT-related hyperuricemia (HRH). In cultured cells, loss of HPRT activity gives rise to 6-thioguanine (6-TG) resistance. In general, cells from LND patients are also 6-TG resistant, whereas cells from HRH patients are not, with some interesting exceptions. Using modeling methods, we have studied the correlation between the mutable and nonmutated amino acid residues on one hand, and sequence conservation and predicted phenotypic effects on the other hand. Our results demonstrate that most of the mutations are explainable by the predicted effect on protein structure and function. They are also consistent with sequence conservation. Moreover, the mutational profiles of TG-resistant cells and LND overlap to a great extent, while most of the mutations in HRH are unique to that condition. We have also noticed a strong correlation between mutations in the tetramer interfaces and observed phenotypes, suggesting a functional role for a tetramer transition during catalysis.
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Affiliation(s)
- Jianxin Duan
- Department of Biosciences at Novum, Center for Structural Biochemistry, Karolinska Institutet, Huddinge, Sweden.
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41
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Rice SC, Vacek P, Homans AH, Messier T, Rivers J, Kendall H, Finette BA. Genotoxicity of therapeutic intervention in children with acute lymphocytic leukemia. Cancer Res 2004; 64:4464-71. [PMID: 15231655 DOI: 10.1158/0008-5472.can-03-3940] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The survival rates of children treated for cancer have dramatically increased after the development of standardized multiple-modality treatment protocols. As a result, there is a rapidly growing population of pediatric cancer survivors in which the long-term genotoxic effects of chemotherapeutic intervention is unknown. To study the genotoxic effects of antineoplastic treatment in children, we performed a comparative analysis of the changes in the frequency of somatic mutations (Mfs) at the hypoxanthine-guanine phosphoribosyltransferase (HPRT)-reporter gene in children treated for acute lymphocytic leukemia (ALL). We measured HPRT Mfs from 130 peripheral blood samples from 45 children with ALL (13, low risk; 22, standard risk; and 10, high risk) from the time of diagnosis, as well as during and after the completion of therapy. We observed a significant increase in mean HPRT Mfs during each phase of therapy (diagnosis, 1.4 x 10(-6); consolidation, 52.1 x 10(-6); maintenance, 93.2 x 10(-6); and off-therapy, 271.7 x 10(-6)) that were independent of the risk group treatment protocol used. This 200-fold increase in mean somatic Mf remained elevated years after the completion of therapy. We did not observe a significant difference in the genotoxicity of each risk group treatment modality despite differences in the compositional and clinical toxicity associated with these treatment protocols. These findings suggest that combination chemotherapy used to treat children with ALL is quite genotoxic, resulting in an increased somatic mutational load that may result in an elevated risk for the development of multi-factorial diseases, in particular second malignancies.
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Affiliation(s)
- Sederick C Rice
- Department of Pediatrics, University of Vermont, Burlington 05405, USA
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Scott BR, Walker DM, Walker VE. Low-dose radiation and genotoxic chemicals can protect against stochastic biological effects. NONLINEARITY IN BIOLOGY, TOXICOLOGY, MEDICINE 2004; 2:185-211. [PMID: 19330143 PMCID: PMC2657487 DOI: 10.1080/15401420490507602] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A protective apoptosis-mediated (PAM) process that is turned on in mammalian cells by low-dose photon (X and gamma) radiation and appears to also be turned on by the genotoxic chemical ethylene oxide is discussed. Because of the PAM process, exposure to low-dose photon radiation (and possibly also some genotoxic chemicals) can lead to a reduction in the risk of stochastic effects such as problematic mutations, neoplastic transformation (an early step in cancer occurrence), and cancer. These findings indicate a need to revise the current low-dose risk assessment paradigm for which risk of cancer is presumed to increase linearly with dose (without a threshold) after exposure to any amount of a genotoxic agent such as ionizing radiation. These findings support a view seldom mentioned in the past, that cancer risk can actually decrease, rather than increase, after exposure to low doses of photon radiation and possibly some other genotoxic agents. The PAM process (a form of natural protection) may contribute substantially to cancer prevention in humans and other mammals. However, new research is needed to improve our understanding of the process. The new research could unlock novel strategies for optimizing cancer prevention and novel protocols for low-dose therapy for cancer. With low-dose cancer therapy, normal tissue could be spared from severe damage while possibly eliminating the cancer.
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Affiliation(s)
- Bobby R Scott
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico
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Lin YW, Perkins JJ, Zhang Z, Aplan PD. Distinct mechanisms lead to HPRT gene mutations in leukemic cells. Genes Chromosomes Cancer 2004; 39:311-23. [PMID: 14978792 DOI: 10.1002/gcc.20005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Leukemias are considered malignant clonal disorders arising from the accumulation of mutations in hematopoietic cells; the majority of these mutations are thought to be acquired somatically. Measurement of mutation frequency (Mf) at the hypoxanthine phosphoribosyltransferase (HPRT) locus has been developed as a method for estimating genomic instability. We investigated the Mf in 16 leukemic cell lines to determine whether these cell lines showed evidence of genomic instability. Although some leukemic cell lines had markedly elevated Mfs, the Mfs at the HPRT locus in leukemic cell lines were not always higher than those of B-lymphoblastoid cell lines and T lymphocytes from normal individuals. We were able to identify the HPRT mutation for 159 of 160 individual HPRT mutants. The HPRT mutations were characterized at a molecular level and classified as either gross chromosomal rearrangements (GCRs) or point mutations, such as single-nucleotide substitutions, insertions, or deletions. With rare exceptions, individual leukemic cell lines showed either point mutations or GCR, but not both. Of note, all the cell lines that primarily showed point mutations are known to be defective in mismatch repair machinery.
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Affiliation(s)
- Ying-Wei Lin
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20889-510, USA.
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Malling HV. Incorporation of mammalian metabolism into mutagenicity testing. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2004; 566:183-9. [PMID: 15082236 DOI: 10.1016/j.mrrev.2003.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/16/2003] [Indexed: 10/26/2022]
Abstract
In the 1950's and 1960's it became obvious that many chemicals in daily use were mutagenic or carcinogenic, but there seemed to be little relation between the two activities. As scientists were debating the cause of this discrepancy, it was hypothesized that mammalian metabolism could form highly reactive intermediates from rather innocuous chemicals and that these intermediates could react with DNA and were mutagenic. This commentary presents the historical development of metabolic activation in mutagenicity tests, beginning with Udenfriend's hydroxylation system, which mimics aspects of mammalian metabolism in a purely chemical mixture, and extending through procedures that moved closer and closer to incorporating actual mammalian metabolism into the test systems. The stages include microsomal activation systems, host-mediated assays, incorporation of human P450 genes into the target cells or organisms, and detecting mutations in single cells in vivo. A recent development in this progression is the insertion of recoverable vectors containing mutational targets into the mammalian genome. Since the target genes of transgenic assays are in the genome, they are not only exposed to active metabolites, but they also undergo the same repair processes as endogenous genes of the mammalian genome.
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Affiliation(s)
- Heinrich V Malling
- Mammalian Mutagenesis Group, Laboratory of Toxicology, Environmental Toxicology Program, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA.
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Cattaneo D, Perico N, Remuzzi G. From pharmacokinetics to pharmacogenomics: a new approach to tailor immunosuppressive therapy. Am J Transplant 2004; 4:299-310. [PMID: 14961981 DOI: 10.1111/j.1600-6143.2004.00312.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
One of the main tasks in the management of organ transplantation is the optimization of immunosuppressive therapy, in order to provide therapeutic efficacy limiting drug-related toxicity. In the past years major efforts have been carried out to define therapeutic windows based on blood/plasma levels of each immunosuppressant relating those concentrations to drug dosing and clinical events. Although this traditional approach is able to identify environmental and nongenetic factors that can influence drug exposure during the course of treatment, it presents limitations. Therefore, complementary strategies are advocated. The advent of the genomic era gives birth to pharmacogenomics, a science that studies how the genome as a whole, including single genes as well as gene-to-gene interactions, may affect the action of a drug. This science is of particular importance for drugs characterized by a narrow therapeutic index, such as the immunosuppressants. Preliminary studies focused on polymorphisms of genes encoding for enzymes actively involved in drug metabolism, drug transport and pharmacological target. Pharmacogenomics holds promise for improvement in the ability to individualize immunosuppressive therapy based on the patient's genetic profile, and can be viewed as a support to traditional therapeutic drug monitoring. However, the clinical applicability of this approach is still to be proven.
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Affiliation(s)
- Dario Cattaneo
- Department of Medicine and Transplantation, Ospedali Riuniti di Bergamo-Mario Negri Institute for Pharmacological Research, Bergamo, Italy.
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46
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Malling HV. History of the science of mutagenesis from a personal perspective. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2004; 44:372-386. [PMID: 15529325 DOI: 10.1002/em.20064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A career in the study of mutagenesis spanning 50 years is a gift few scientists have been bestowed. My tenure in the field started in 1953, the year the structure of DNA became known (Watson and Crick [1953]: Nature 171:737). Before that time, it was suspected that DNA was the genetic material based on the research of Oswald T. Avery (Avery et al. [1944]: J Exp Med 79:137), but many scientists still believed that proteins or polysaccharides could be the genetic material. The present article describes a lifetime of personal experience in the field of chemical mutagenesis. The methods used to treat viruses with chemical mutagens were well developed in the 1950s. Here I review the early use of nitrous acid and hydroxylamine as mutagens in eukaryotes, the development of methods for the metabolic activation of mutagens by microsomal preparations, and the selection of a mutant tester set for the qualitative characterization of the mutagenic activity of chemicals. These studies provided critical background information that was used by Bruce Ames in the development of his Salmonella/microsome assay, widely known as the Ames test (Ames et al. [1973]: Proc Nat Acad Sci USA 70:2281-2285). This article also describes how a set of diagnostic chemical mutagens was selected and used to identify the molecular nature of gene mutations. Today, DNA sequencing has replaced the use of diagnostic mutagens, but studies of this kind formed the foundation of modern mutation research. They also helped set the stage for the organization of the Environmental Mutagen Society and the Environmental Mutagen Information Center, which are described. The article ends with the development of mammalian single-cell mutation assays, the first system for studying in vivo mutagenesis using recoverable vectors in transgenic animals, other mutation assays in intact mammals, and my thoughts on the critically important area of germ cell mutagenesis. This narrative is not a complete autobiographical account, in that I have selected only those experiences that I feel are important for the history of the field and the edification of today's students. I hope I have shown that science not only is a valuable pursuit but can also be fun, stimulating, and satisfying. A good sense of humor and the knowledge that many discoveries come by serendipity are essential.
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Affiliation(s)
- Heinrich V Malling
- Laboratory of Toxicology, Environmental Toxicology Program, Department of Human Health Services, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
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Wijnhoven SWP, van Steeg H. Transgenic and knockout mice for DNA repair functions in carcinogenesis and mutagenesis. Toxicology 2003; 193:171-87. [PMID: 14599776 DOI: 10.1016/s0300-483x(03)00295-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Genetically modified mouse models with defects in DNA repair pathways, especially in nucleotide excision repair (NER) and mismatch repair (MMR), are powerful tools to study processes like carcinogenesis and mutagenesis. The use of mutant mice in these studies has many advantages over using normal wild type mice with respect to costs, number of animals, predictive value towards carcinogenic compounds and the duration of study. Short-term carcinogenicity assays still require considerable number of animals and extensive pathological analyses. Therefore, alternatives demanding less animals and shorter exposure times would be desirable. In this respect, one approach could be the use of transgenic mice harbouring marker genes, that can easily detect mutagenic features of carcinogenic compounds, especially when such models are in a DNA repair deficient background. Here, we review the progress made in the development and use of DNA repair deficient mouse models as replacements for long-term cancer assays and discuss the applicability of enhanced gene mutant frequencies as early indicators of tumourigenesis. Although promising models exist, there is still a need for more universally responding and highly sensitive mouse models, since it is likely that non-genotoxic carcinogens will go undetected in a DNA repair deficient mouse. One attractive candidate mouse model, having a presumptive broad detective range, is the Xpa/p53 mutant mouse model, which will be discussed in more detail.
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Affiliation(s)
- Susan W P Wijnhoven
- National Institute of Public Health and Environment, RIVM/TOX pb12, P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
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Kim AS, Thilly WG. Ligation of high-melting-temperature 'clamp' sequence extends the scanning range of rare point-mutational analysis by constant denaturant capillary electrophoresis (CDCE) to most of the human genome. Nucleic Acids Res 2003; 31:e97. [PMID: 12907749 PMCID: PMC169989 DOI: 10.1093/nar/gng099] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mutations cause or influence the prevalence of many diseases. In human tissues, somatic point mutations have been observed at fractions at or below 4/10,000 and 5/100,000 in mitochondrial and nuclear DNA, respectively. In human populations, fractions for the multiple alleles that code for recessive deleterious syndromes are not expected to exceed 5 x 10(-4). Both nuclear and mitochondrial point mutations have been measured in human cells and tissues at fractions approaching 10(-6) using constant denaturant capillary electrophoresis (CDCE) coupled with high-fidelity PCR (hifiPCR). However, this approach is only applicable to those target sequences (approximately 100 bp) juxtaposed with a 'clamp', a higher-melting-temperature sequence, in genomic DNA; such naturally clamped targets represent approximately 9% of the human genome. To open up most of the human genome to rare point-mutational analysis, a high-efficiency DNA ligation procedure was recently developed so that a clamp could be attached to any target of interest. We coupled this ligation procedure with prior CDCE/hifiPCR and achieved a sensitivity of 2 x 10(-5) in human cells for the first time using an externally attached clamp. At this sensitivity, somatic mutations, each representing an anatomically distinct cluster of cells (turnover unit) derived from a mutant stem cell, may be detected in a series of tissue samples, each containing as many as 5 x 10(4) turnover units. Additionally, rare inherited mutations may be scanned in pooled DNA samples, each derived from as many as 10(5) persons.
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Affiliation(s)
- Andrea S Kim
- Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Mognato M, Bortoletto E, Ferraro P, Baggio L, Cherubini R, Canova S, Russo A, Celotti L. Genetic damage induced by in vitro irradiation of human G0 lymphocytes with low-energy protons (28 keV/microm): HPRT mutations and chromosome aberrations. Radiat Res 2003; 160:52-60. [PMID: 12816523 DOI: 10.1667/0033-7587(2003)160[0052:gdibiv]2.0.co;2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cell survival, mutations and chromosomal effects were studied in primary human lymphocytes exposed in G0 phase to a proton beam with an incident energy of 0.88 MeV (incident LET of 28 keV/microm) in the dose range 0.125-2 Gy. The curves for survival and mutations at the hypoxanthine-guanine phosphoribosyl transferase locus were obtained by fitting the experimental data to linear and linear-quadratic equations, respectively. In the dose interval 0-1.5 Gy, the alpha parameters of the curves were 0.42/Gy and 3.6 x 10(-6) mutants/Gy, respectively. The mutation types at the HPRT locus were analyzed by multiplex-PCR in 94 irradiated and 41 nonirradiated clones derived from T lymphocytes from five healthy donors. All clones showed a normal multiplex-PCR pattern and were classified as point mutations. Chromosome aberration data were fitted as a linear function of dose (alpha = 0.62 aberrations per cell Gy(-1)). By irradiating G0 lymphocytes from a single subject with 28 keV/microm protons and gamma rays, an RBE of 6.07 was obtained for chromosome aberrations. An overinvolvement of chromosome 9 relative to chromosome 7 was found in chromosome breaks after chromosome painting analysis.
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50
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Liakata E, Philippou G, Souvatzoglou A, Lymberi P, Carayanniotis G. Assessment of the frequency of mutant (hprt-) T lymphocytes from peripheral blood of patients with Hashimoto's thyroiditis. Thyroid 2003; 13:631-6. [PMID: 12964967 DOI: 10.1089/105072503322239961] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A salient feature of Hashimoto's thyroiditis (HT) is the T-cell-mediated destruction of the thyroid gland leading to hypothyroidism. In HT, as in other autoimmune diseases, a central premise has been that autoreactive T cells must be dividing in response to autoantigens, accumulating random spontaneous mutations during the activation process. Here, we have examined this hypothesis by using as monitor of somatic cell mutation the hprt gene, encoding the salvage pathway enzyme hypoxanthine-guanine phosphoribosyl transferase. Eleven newly diagnosed patients with HT and 10 patients with chronic disease were selected for the study, whereas 10 healthy individuals were used as controls. Peripheral T cells were cultured under limiting dilution conditions in the presence of 6-thioguanine and the frequency (MF) of surviving mutant hprt(-) T cells was calculated by Poisson statistics. It was observed that the mean MF value of either patient group (6.6 +/- 5.8 per 10(6) cells for the newly diagnosed, and 8.8 +/- 4.0 per 10(6) cells for the patients with chronic disease) was not significantly different (p > 0.05) from that of the control group (6.8 +/- 6.4 per 10(6) cells). These data do not support the concept that patients with HT have an increased number of actively dividing T cells in the circulation compared to healthy controls. Autoreactive T cells may be activated mainly in situ or home readily to the thyroid in the early stages of the disease and reach a nonexpansion stage as the chronic disease is stabilized.
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Affiliation(s)
- E Liakata
- Immunology Laboratory, Department of Biochemistry, Hellenic Pasteur Institute, Athens, Greece
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