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Maura F, Ziccheddu B, Xiang JZ, Bhinder B, Rosiene J, Abascal F, Maclachlan KH, Eng KW, Uppal M, He F, Zhang W, Gao Q, Yellapantula VD, Trujillo-Alonso V, Park SI, Oberley MJ, Ruckdeschel E, Lim MS, Wertheim GB, Barth MJ, Horton TM, Derkach A, Kovach AE, Forlenza CJ, Zhang Y, Landgren O, Moskowitz CH, Cesarman E, Imielinski M, Elemento O, Roshal M, Giulino-Roth L. Molecular Evolution of Classic Hodgkin Lymphoma Revealed Through Whole-Genome Sequencing of Hodgkin and Reed Sternberg Cells. Blood Cancer Discov 2023; 4:208-227. [PMID: 36723991 PMCID: PMC10150291 DOI: 10.1158/2643-3230.bcd-22-0128] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 11/21/2022] [Accepted: 01/26/2023] [Indexed: 02/02/2023] Open
Abstract
The rarity of malignant Hodgkin and Reed Sternberg (HRS) cells in classic Hodgkin lymphoma (cHL) limits the ability to study the genomics of cHL. To circumvent this, our group has previously optimized fluorescence-activated cell sorting to purify HRS cells. Using this approach, we now report the whole-genome sequencing landscape of HRS cells and reconstruct the chronology and likely etiology of pathogenic events leading to cHL. We identified alterations in driver genes not previously described in cHL, APOBEC mutational activity, and the presence of complex structural variants including chromothripsis. We found that high ploidy in cHL is often acquired through multiple, independent chromosomal gains events including whole-genome duplication. Evolutionary timing analyses revealed that structural variants enriched for RAG motifs, driver mutations in B2M, BCL7A, GNA13, and PTPN1, and the onset of AID-driven mutagenesis usually preceded large chromosomal gains. This study provides a temporal reconstruction of cHL pathogenesis. SIGNIFICANCE Previous studies in cHL were limited to coding sequences and therefore not able to comprehensively decipher the tumor complexity. Here, leveraging cHL whole-genome characterization, we identify driver events and reconstruct the tumor evolution, finding that structural variants, driver mutations, and AID mutagenesis precede chromosomal gains. This article is highlighted in the In This Issue feature, p. 171.
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Affiliation(s)
- Francesco Maura
- Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
| | - Bachisio Ziccheddu
- Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
| | - Jenny Z. Xiang
- Weill Cornell Medical College, New York, New York
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medical College, New York, New York
| | - Bhavneet Bhinder
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medical College, New York, New York
| | - Joel Rosiene
- Weill Cornell Medical College, New York, New York
| | - Federico Abascal
- The Cancer, Ageing and Somatic Mutation Programme, Wellcome Sanger Institute, Hinxton, United Kingdom
| | - Kylee H. Maclachlan
- Myeloma Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Kenneth Wha Eng
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medical College, New York, New York
| | - Manik Uppal
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medical College, New York, New York
| | - Feng He
- Weill Cornell Medical College, New York, New York
| | - Wei Zhang
- Weill Cornell Medical College, New York, New York
| | - Qi Gao
- Memorial Sloan Kettering Cancer Center, New York, New York
| | - Venkata D. Yellapantula
- Myeloma Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
- Department of Pathology and Laboratory Medicine at Children's Hospital Los Angeles, Los Angeles, California
| | | | - Sunita I. Park
- Department of Pathology, Children's Hospital of Atlanta, Atlanta, Georgia
| | | | | | - Megan S. Lim
- Department of Pathology, Children's Hospital of Philadelphia, Philadelphia, Philadelphia
| | - Gerald B. Wertheim
- Department of Pathology, Children's Hospital of Philadelphia, Philadelphia, Philadelphia
| | - Matthew J. Barth
- Department of Pediatrics, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Terzah M. Horton
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Andriy Derkach
- Department of Epidemiology and Statistics, Memorial Sloan Kettering Cancer Center, New York, New York
| | | | | | - Yanming Zhang
- Memorial Sloan Kettering Cancer Center, New York, New York
| | - Ola Landgren
- Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
| | - Craig H. Moskowitz
- Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
| | | | - Marcin Imielinski
- Weill Cornell Medical College, New York, New York
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medical College, New York, New York
- Myeloma Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Olivier Elemento
- Weill Cornell Medical College, New York, New York
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medical College, New York, New York
| | - Mikhail Roshal
- Memorial Sloan Kettering Cancer Center, New York, New York
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Revollo JR, McKinzie PB, Robison TW, Dobrovolsky VN. Mutational signatures in T-lymphocytes of rats treated with N-propyl-N-nitrosourea and procarbazine. Environ Mol Mutagen 2021; 62:350-363. [PMID: 34117657 DOI: 10.1002/em.22448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/12/2021] [Accepted: 06/09/2021] [Indexed: 06/12/2023]
Abstract
We have used whole genome sequencing (WGS) to determine mutational signatures induced in the T-cells of rats treated in vivo with N-propyl-N-nitrosourea (PNU) or procarbazine (PCZ). The signatures from the treated rats were different from the signature of background mutations. The main component of the spontaneous T-cell mutational signature was C➔T transition with all other single base substitutions evenly distributed. The PNU-induced mutational signature showed relatively equal contributions from C➔T and T➔C transitions, and T➔A transversions. The PCZ-induced signature was characterized by T➔C transitions, T➔A and, to a smaller extent, T➔G transversions. C➔G transversions were infrequent in either the PNU or PCZ signatures. WGS not only allowed mutational signature detection, but also measured quantitative responses to mutagen treatment: 10-40× increases in the number of mutations per clone were detected in T-cell clones from treated rats. The overall strand specificity of induced mutations for annotated rat genes was comparable to the strand specificity of mutations determined previously for the endogenous X-linked Pig-a gene. Our results provide valuable reference data for future applications of WGS in safety research and risk assessment.
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Affiliation(s)
- Javier R Revollo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
| | - Page B McKinzie
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
| | - Timothy W Robison
- Division of Pulmonary, Allergy and Critical Care Products, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
| | - Vasily N Dobrovolsky
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
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Revollo JR, Dad A, Pearce MG, Mittelstaedt RA, Casildo A, Lapidus RG, Robison TW, Dobrovolsky VN. CD59-deficient bone marrow erythroid cells from rats treated with procarbazine and propyl-nitrosourea have mutations in the Pig-a gene. Environ Mol Mutagen 2020; 61:797-806. [PMID: 32729949 DOI: 10.1002/em.22402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/09/2020] [Accepted: 07/24/2020] [Indexed: 06/11/2023]
Abstract
Procarbazine (PCZ) and N-propyl-N-nitrosourea (PNU) are rodent mutagens and carcinogens. Both induce GPI-anchored marker-deficient mutant-phenotype red blood cells (RBCs) in the flow cytometry-based rat RBC Pig-a assay. In the present study, we traced the origin of the RBC mutant phenotype by analyzing Pig-a mutations in the precursors of RBCs, bone marrow erythroid cells (BMEs). Rats were exposed to a total of 450 mg/kg PCZ hydrochloride or 300 mg/kg PNU, and bone marrow was collected 2, 7, and 10 weeks later. Using a flow cell sorter, we isolated CD59-deficient mutant-phenotype BMEs from PCZ- and PNU-treated rats and examined their endogenous X-linked Pig-a gene by next generation sequencing. Pig-a mutations consistent with the properties of PCZ and PNU were found in sorted mutant-phenotype BMEs. PCZ induced mainly A > T transversions with the mutated A on the nontranscribed strand of the Pig-a gene, while PNU induced mainly T > A transversions with the mutated T on the nontranscribed strand. The treatment-induced mutations were distributed across the protein coding sequence of the Pig-a gene. The causal relationship between BMEs and RBCs and the agent-specific mutational spectra in CD59-deicient BMEs indicate that the rat RBC Pig-a assay, scoring CD59-deficient mutant-phenotype RBCs in peripheral blood, detects Pig-a gene mutation.
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Affiliation(s)
- Javier R Revollo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas, USA
| | - Azra Dad
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas, USA
| | - Mason G Pearce
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas, USA
| | - Roberta A Mittelstaedt
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas, USA
| | - Andrea Casildo
- Greenbaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Rena G Lapidus
- Greenbaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Timothy W Robison
- Division of Pulmonary, Allergy and Critical Care Products, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Vasily N Dobrovolsky
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas, USA
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Maurice C, Dertinger SD, Yauk CL, Marchetti F. Integrated In Vivo Genotoxicity Assessment of Procarbazine Hydrochloride Demonstrates Induction of Pig-a and LacZ Mutations, and Micronuclei, in MutaMouse Hematopoietic Cells. Environ Mol Mutagen 2019; 60:505-512. [PMID: 30592561 PMCID: PMC6618172 DOI: 10.1002/em.22271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 12/21/2018] [Accepted: 12/26/2018] [Indexed: 06/09/2023]
Abstract
Procarbazine hydrochloride (PCH) is a DNA-reactive hematopoietic carcinogen with potent and well-characterized clastogenic activity. However, there is a paucity of in vivo mutagenesis data for PCH, and in vitro assays often fail to detect the genotoxic effects of PCH due to the complexity of its metabolic activation. We comprehensively evaluated the in vivo genotoxicity of PCH on hematopoietic cells of male MutaMouse transgenic rodents using a study design that facilitated assessments of micronuclei and Pig-a mutation in circulating erythrocytes, and lacZ mutant frequencies in bone marrow. Mice were orally exposed to PCH (0, 6.25, 12.5, and 25 mg/kg/day) for 28 consecutive days. Blood samples collected 2 days after cessation of treatment exhibited significant dose-related induction of micronuclei in both immature and mature erythrocytes. Bone marrow and blood collected 3 and 70 days after cessation of treatment also showed significantly elevated mutant frequencies in both the lacZ and Pig-a assays even at the lowest dose tested. PCH-induced lacZ and Pig-a (immature and mature erythrocytes) mutant frequencies were highly correlated, with R2 values ≥0.956, with the exception of lacZ vs. Pig-a mutants in mature erythrocytes at the 70-day time point (R2 = 0.902). These results show that PCH is genotoxic in vivo and demonstrate that the complex metabolism and resulting genotoxicity of PCH is best evaluated in intact animal models. Our results further support the concept that multiple biomarkers of genotoxicity, especially hematopoietic cell genotoxicity, can be readily combined into one study provided that adequate attention is given to manifestation times. Environ. Mol. Mutagen. 60:505-512, 2019. © 2018 Her Majesty the Queen in Right of Canada.
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Affiliation(s)
- Clotilde Maurice
- Environmental Health Science and Research BureauHealth CanadaOttawaOntarioCanada
| | | | - Carole L. Yauk
- Environmental Health Science and Research BureauHealth CanadaOttawaOntarioCanada
| | - Francesco Marchetti
- Environmental Health Science and Research BureauHealth CanadaOttawaOntarioCanada
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Abstract
In this review, genotoxic and mutagenic effects of teratogenic chemical agents in both rat and mouse have been reviewed. Of these chemicals, 97 are drugs and 33 are pesticides or belong to other groups. Large literature searches were conducted to determine the effects of chemicals on chromosome abnormalities, sister chromatid exchanges, and micronucleus formation in experimental animals such as rats and mice. In addition, studies that include unscheduled DNA synthesis, DNA adduct formations, and gene mutations, which help to determine the genotoxicity or mutagenicity of chemicals, have been reviewed. It has been estimated that 46.87% of teratogenic drugs and 48.48% of teratogenic pesticides are positive in all tests. So, all of the teratogens involved in this group have genotoxic and mutagenic effects. On the other hand, 36.45% of the drugs and 21.21% of the pesticides have been found to give negative results in at least one test, with the majority of the tests giving positive results. However, only 4.16% of the drugs and 18.18% of the pesticides were determined to give negative results in the majority of the tests. Among tests with major negative results, 12.50% of the teratogenic drugs and 12.12% of the teratogenic pesticides were negative in all conducted tests.
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Affiliation(s)
- Eyyüp Rencüzoğulları
- a Department of Biology, Faculty of Science and Letters , Adiyaman University , Adiyaman , Turkey
| | - Muhsin Aydın
- a Department of Biology, Faculty of Science and Letters , Adiyaman University , Adiyaman , Turkey
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Revollo J, Bhalli JA, Tebbe C, Noteboom J, Thomas D, McKinzie P, Felton N, Pearce MG, Dobrovolsky VN. Spectrum of Pig-a mutations in T lymphocytes of rats treated with procarbazine. Mutagenesis 2017; 32:571-579. [DOI: 10.1093/mutage/gex032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/19/2017] [Indexed: 01/22/2023] Open
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7
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Phonethepswath S, Avlasevich SL, Torous DK, Mereness J, Bemis JC, Macgregor JT, Dertinger SD. Flow cytometric analysis of Pig-a gene mutation and chromosomal damage induced by procarbazine hydrochloride in CD-1 mice. Environ Mol Mutagen 2013; 54:294-298. [PMID: 23427001 DOI: 10.1002/em.21758] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 12/13/2012] [Accepted: 12/12/2012] [Indexed: 06/01/2023]
Abstract
Procarbazine is a genotoxic carcinogen whose DNA-damaging activities are not reliably detected in vitro. We evaluated the in vivo genotoxic effects of procarbazine on hematopoietic cells of male CD-1 mice using a multi-endpoint study design that scored micronucleated reticulocyte (MN-RET) frequency and gene mutation at the Pig-a locus. CD-1 mice were treated for 3 days with procarbazine, up to 150 mg/kg/day. Blood samples collected on Day 3 exhibited robust induction of MN-RETs, with the high dose group exhibiting a mean 29-fold increase. Blood collected 15 and 30 days after treatment began was analyzed for Pig-a mutation with a dual labeling method that facilitated mutant cell frequency measurements in both total erythrocytes and the reticulocyte subpopulation. Procarbazine significantly increased mutant reticulocyte frequencies by Day 15. Mutant erythrocyte responses were also apparent, with a peak incidence observed for the high dose group on Day 30. These results demonstrate that the complex metabolism and resulting genotoxicity of procarbazine is best evaluated in intact animal models, and show that the flow cytometric methods employed offer a means to efficiently monitor both in vivo chromosomal damage and mutation.
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Suzuki T, Uno Y, Idehara K, Baba T, Maniwa J, Ohkouchi A, Wang X, Hayashi M, Sofuni T, Tsuruoka M, Miyajima H, Kondo K. Procarbazine genotoxicity in the MutaMouse; strong clastogenicity and organ-specific induction of lacZ mutations. Mutat Res 1999; 444:269-81. [PMID: 10521668 DOI: 10.1016/s1383-5718(99)00060-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Procarbazine, a drug used for cancer chemotherapy, is carcinogenic in rodent bioassays. We analyzed the mutagenicity of procarbazine in various organs and the clastogenicity of the drug in hematopoietic cells of the lacZ transgenic MutaMouse. This was part of the second collaborative study of the Mammalian Mutagenesis Study Group of the Japanese Environmental Mutagen Society on the transgenic mouse mutation assay. At 50 mg kg(-1), procarbazine induced micronuclei in hematopoietic cells, but it did not increase the lacZ mutant frequency (MF) in bone marrow. It was also negative in liver, testis, spleen, kidney, and lung. Five daily administrations of 150 mg kg(-1) yielded highly positive responses in the drug's target organs for carcinogenesis (lung, bone marrow, and spleen). Lower positive responses were detected in kidney, which is a minor target organ. Liver showed only a slight increase in lacZ MF and brain showed no increase. The testis MF more than doubled which suggest that procarbazine is mutagenic to germ cells. Thus, we demonstrated that procarbazine has a strong clastogenic effect in hematopoietic cells and is mutagenic in a variety organs after high dose treatment. The induced MF was especially high in procarbazine's target organs for carcinogenesis, which supports the relevance of the transgenic mouse mutation assay for the assessment of potential genotoxins in vivo.
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Affiliation(s)
- T Suzuki
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, Japan.
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Abstract
We report two patients with acute myeloid leukemia (AML) following therapy for malignant glioma; one was a young women treated heavily with alkylating agents for glioblastoma and the other a young man treated with high doses of procarbazine, lomustine, and vincristine (PCV) for anaplastic astrocytoma. We found 26 other examples of therapy related leukemia in adult and pediatric brain tumor patients. Including our two, there were 12 patients with malignant glioma; median interval from treatment to diagnosis of AML was 31 months. Nine adult malignant glioma patients all received nitrosoureas, some as the sole form of chemotherapy. No definite cases occurred after radiotherapy alone. Based upon analogy with other cancers, the cumulative dose of chemotherapy, especially alkylating agents, is the major risk factor for development of secondary AML. Agents implicated include carmustine (BCNU), lomustine (CCNU), and procarbazine. Conventional radiotherapy appears not to confer additional risk. Progressive macrocytosis, early dose reductions for thrombocytopenia, and refractory anemia may provide early diagnostic clues. Current glioma therapy is leukemogenic but the number of patients who survive the interval required to induce AML is small; nevertheless, the identification of chemosensitive types of glioma, and subgroups of patients who derive the most benefit from chemotherapy, may result in increasing numbers of patients at risk of long term complications. If regimens such as PCV continue to prove valuable in neurooncology the risk of leukemia will require integration into the clinical decision process. A search for more effective therapy with minimal mutagenicity remains critical.
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Affiliation(s)
- J R Perry
- Division of Neurology, Duke University Medical Center, Durham, NC, USA
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Mitchell AD, Auletta AE, Clive D, Kirby PE, Moore MM, Myhr BC. The L5178Y/tk+/- mouse lymphoma specific gene and chromosomal mutation assay a phase III report of the U.S. Environmental Protection Agency Gene-Tox Program. Mutat Res 1997; 394:177-303. [PMID: 9434856 DOI: 10.1016/s1383-5718(97)00115-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The L5178Y/tk+/- (-)3.7.2C mouse lymphoma assay (MLA) which detects mutations affecting the heterozygous thymidine kinase (tk) locus is capable of responding to chemicals acting as clastogens as well as point mutagens. Improvements in the assay to enhance detection of this spectrum of genetic events are summarized, and criteria for evaluating the data are defined. Using these criteria, the Phase III Work Group reviewed and evaluated literature containing MLA results published from 1976 through 1993. The data base included 602 chemicals of which 343 were evaluated as positive, 44 negative, 18 equivocal, 54 apparently inappropriate for evaluation in this test system with the published protocols, and 142 that were inadequately tested, and thus a definitive call could not be made. The overall performance of the assay is summarized by chemical class, and the outcome of testing 260 chemicals in the MLA is compared with Gene-Tox and National Toxicology Program evaluations of rodent carcinogenesis bioassay results for the same chemicals. Based on the Work Group's evaluation of published MLA data for chemicals that were considered adequately tested, it is concluded that for most chemicals the L5178Y/tk+/- mouse lymphoma assay is eminently well suited for genotoxicity testing and for predicting the potential for carcinogenicity.
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Affiliation(s)
- A D Mitchell
- Genesys Research, Incorporated, Research Triangle Park, NC 27709, USA
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12
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Abstract
The phenotypic stability of over 2000 large- and small-colony trifluorothymidine-resistant (TFTres) variants of L5178Y/tk(+/-)-3.7.2C cells has been examined. All except 4 of 488 spontaneously arising small-colony variants analyzed (0.8%) retained the TFTres phenotype when rechallenged with TFT after growth for several generations in its absence. All of 558 spontaneous large-colony variants, and 440 small-colony or 487 large-colony variants arising from 13 different mutagens showed similar stability. These results attest to the completeness of TFT selection in the mouse-lymphoma assay when used at 1 microgram/ml in Fischer's medium supplemented with heat-inactivated serum and, together with previous cytogenetic and molecular studies, justify considering essentially all such TFTres variants as stable mutants. The implications of these results for those versions of the mouse lymphoma assay that fail to optimize the recovery and scoring of small-colony mutants is discussed.
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Affiliation(s)
- D Clive
- Burroughs Wellcome Co., Research Triangle Park, NC 27709
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Brockman HE, de Serres FJ. Mutagenic potency and specificity of procarbazine in the ad-3 forward-mutation test in growing cultures of heterokaryon 12 of Neurospora crassa. Mutat Res 1991; 246:193-204. [PMID: 1824718 DOI: 10.1016/0027-5107(91)90122-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Procarbazine (Natulan) was tested for its mutagenic potency and specificity in the ad-3 forward-mutation test in heterokaryon 12 (H-12) of Neurospora crassa. In these experiments, procarbazine was a weak mutagen when present in growing cultures but nonmutagenic when conidial suspensions (nongrowing conidia) were treated. A total of 208 ad-3 mutants recovered after exposure of growing cultures of H-12 to 1 mg of procarbazine/ml, and 2 ad-3 mutants of spontaneous origin, were characterized genetically. These tests distinguish among gene/point mutations (ad-3R) at the ad-3A or ad-3B locus, multilocus deletion mutations ([ad-3]IR) covering one or more loci in the ad-3 and immediately adjacent regions, and 3 different classes of multiple-locus mutations: gene/point ad-3 mutations with a recessive lethal mutation elsewhere in the genome (ad-3R + RL), gene/point mutations with a closely linked recessive lethal mutation (ad-3R + RLCL), and multilocus deletion mutations with a closely linked recessive lethal mutation ([ad-3]IR + RLCL). All of the procarbazine-induced ad-3 mutants resulted from gene/point mutations; 92.2% (200/217) resulted from gene/point mutations at the ad-3A or ad-3B locus, and 3.7% (8/217) resulted from gene/point mutations with a recessive lethal mutation elsewhere in the genome. Identical percentages (15.4% [20/130] and 15.4% [12/78]) of the sigma ad-3BR and sigma ad-3AR mutants were leaky, and a high percentage (71.5% [93/130]) of the sigma ad-3BR mutants had nonpolarized complementation patterns. These results indicate that procarbazine-induced ad-3 mutants of Neurospora crassa are composed solely of gene/point mutations (ad-3R) that resulted, predominantly or exclusively, from base-pair substitutions. The Neurospora specific-locus data on procarbazine-induced ad-3 mutants are compared with data from similar experiments with the mouse using the morphological specific-locus assay; marked similarities were found between the mutagenic effects of procarbazine in the 2 specific-locus assays.
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Affiliation(s)
- H E Brockman
- Department of Biological Sciences, Illinois State University, Normal 61761
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