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Zhu Y, Ong CS, Huttley GA. Machine Learning Techniques for Classifying the Mutagenic Origins of Point Mutations. Genetics 2020; 215:25-40. [PMID: 32193188 PMCID: PMC7198283 DOI: 10.1534/genetics.120.303093] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 03/05/2020] [Indexed: 11/18/2022] Open
Abstract
There is increasing interest in developing diagnostics that discriminate individual mutagenic mechanisms in a range of applications that include identifying population-specific mutagenesis and resolving distinct mutation signatures in cancer samples. Analyses for these applications assume that mutagenic mechanisms have a distinct relationship with neighboring bases that allows them to be distinguished. Direct support for this assumption is limited to a small number of simple cases, e.g., CpG hypermutability. We have evaluated whether the mechanistic origin of a point mutation can be resolved using only sequence context for a more complicated case. We contrasted single nucleotide variants originating from the multitude of mutagenic processes that normally operate in the mouse germline with those induced by the potent mutagen N-ethyl-N-nitrosourea (ENU). The considerable overlap in the mutation spectra of these two samples make this a challenging problem. Employing a new, robust log-linear modeling method, we demonstrate that neighboring bases contain information regarding point mutation direction that differs between the ENU-induced and spontaneous mutation variant classes. A logistic regression classifier exhibited strong performance at discriminating between the different mutation classes. Concordance between the feature set of the best classifier and information content analyses suggest our results can be generalized to other mutation classification problems. We conclude that machine learning can be used to build a practical classification tool to identify the mutation mechanism for individual genetic variants. Software implementing our approach is freely available under an open-source license.
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Affiliation(s)
- Yicheng Zhu
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Cheng Soon Ong
- Data61, CSIRO, Black Mountain Campus, Canberra, Australian Capital Territory 2601, Australia
- Research School of Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Gavin A Huttley
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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Negishi T, Yamada K, Miyamoto K, Mori E, Taira K, Fujii A, Goto Y, Arimoto-Kobayashi S, Okamoto K. Mismatch repair systems might facilitate the chromosomal recombination induced by N-nitrosodimethylamine, but not by N-nitrosodiethylamine, in Drosophila. Mutagenesis 2020; 35:197-206. [PMID: 32109288 DOI: 10.1093/mutage/geaa008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/03/2020] [Indexed: 11/14/2022] Open
Abstract
Mismatch repair (MMR) systems play important roles in maintaining the high fidelity of genomic DNA. It is well documented that a lack of MMR increases the mutation rate, including base exchanges and small insertion/deletion loops; however, it is unknown whether MMR deficiency affects the frequency of chromosomal recombination in somatic cells. To investigate the effects of MMR on chromosomal recombination, we used the Drosophila wing-spot test, which efficiently detects chromosomal recombination. We prepared MMR (MutS)-deficient flies (spel1(-/-)) using a fly line generated in this study. The spontaneous mutation rate as measured by the wing-spot test was slightly higher in MutS-deficient flies than in wild-type (spel1(+/-)) flies. Previously, we showed that N-nitrosodimethylamine (NDMA)-induced chromosomal recombination more frequently than N-nitrosodiethylamine (NDEA) in Drosophila. When the wing-spot test was performed using MMR-deficient flies, unexpectedly, the rate of NDMA-induced mutation was significantly lower in spel1(-/-) flies than in spel1(+/-) flies. In contrast, the rate of mutation induced by NDEA was higher in spel1(-/-) flies than in spel1(+/-) flies. These results suggest that in Drosophila, the MutS homologue protein recognises methylated DNA lesions more efficiently than ethylated ones, and that MMR might facilitate mutational chromosomal recombination due to DNA double-strand breaks via the futile cycle induced by MutS recognition of methylated lesions.
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Affiliation(s)
- Tomoe Negishi
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan.,Department of Pharmaceutical and Medical Business Sciences, Nihon Pharmaceutical University, Ina, Kita-Adachi-gun, Saitama, Japan
| | - Kenji Yamada
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Keiko Miyamoto
- Faculty of Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Emiko Mori
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Kentaro Taira
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Asei Fujii
- Faculty of Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Yuki Goto
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Sakae Arimoto-Kobayashi
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Keinosuke Okamoto
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
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Zheng L, Zhang Y, Hao S, Chen L, Sun Z, Yan C, Whitin JC, Jang T, Merchant M, McElhinney DB, Sylvester KG, Cohen HJ, Recht L, Yao X, Ling XB. A proteomic clock for malignant gliomas: The role of the environment in tumorigenesis at the presymptomatic stage. PLoS One 2019; 14:e0223558. [PMID: 31600288 PMCID: PMC6786640 DOI: 10.1371/journal.pone.0223558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 09/17/2019] [Indexed: 11/25/2022] Open
Abstract
Malignant gliomas remain incurable with a poor prognosis despite of aggressive treatment. We have been studying the development of brain tumors in a glioma rat model, where rats develop brain tumors after prenatal exposure to ethylnitrosourea (ENU), and there is a sizable interval between when the first pathological changes are noted and tumors become detectable with MRI. Our aim to define a molecular timeline through proteomic profiling of the cerebrospinal fluid (CSF) such that brain tumor commitment can be revealed earlier than at the presymptomatic stage. A comparative proteomic approach was applied to profile CSF collected serially either before, at and after the time MRI becomes positive. Elastic net (EN) based models were developed to infer the timeline of normal or tumor development respectively, mirroring a chronology of precisely timed, “clocked”, adaptations. These CSF changes were later quantified by longitudinal entropy analyses of the EN predictive metric. False discovery rates (FDR) were computed to control the expected proportion of the EN models that are due to multiple hypothesis testing. Our ENU rat brain tumor dating EN model indicated that protein content in CSF is programmed even before tumor MRI detection. The findings of the precisely timed CSF tumor microenvironment changes at presymptomatic stages, deviation from the normal development timeline, may provide the groundwork for the understanding of adaptation of the brain environment in tumorigenesis to devise effective brain tumor management strategies.
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Affiliation(s)
- Le Zheng
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California, United States of America
- Clinical and Translational Research Program, Betty Irene Moore Children's Heart Center, Lucile Packard Children’s Hospital, Palo Alto, California, United States of America
| | - Yan Zhang
- Department of Oncology, the First Hospital of Shijiazhuang, Shijiazhuang, Hebei, China
| | - Shiying Hao
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California, United States of America
- Clinical and Translational Research Program, Betty Irene Moore Children's Heart Center, Lucile Packard Children’s Hospital, Palo Alto, California, United States of America
| | - Lin Chen
- Department of Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - Zhen Sun
- Department of Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - Chi Yan
- Department of Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - John C. Whitin
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Taichang Jang
- Department of Neurology and Neurological Science, Stanford University School of Medicine, Stanford, California, United States of America
| | - Milton Merchant
- Department of Neurology and Neurological Science, Stanford University School of Medicine, Stanford, California, United States of America
| | - Doff B. McElhinney
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California, United States of America
- Clinical and Translational Research Program, Betty Irene Moore Children's Heart Center, Lucile Packard Children’s Hospital, Palo Alto, California, United States of America
| | - Karl G. Sylvester
- Department of Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - Harvey J. Cohen
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Lawrence Recht
- Department of Neurology and Neurological Science, Stanford University School of Medicine, Stanford, California, United States of America
| | - Xiaoming Yao
- Clinical and Translational Research Program, Betty Irene Moore Children's Heart Center, Lucile Packard Children’s Hospital, Palo Alto, California, United States of America
- Department of Surgery, Stanford University School of Medicine, Stanford, California, United States of America
| | - Xuefeng B. Ling
- Clinical and Translational Research Program, Betty Irene Moore Children's Heart Center, Lucile Packard Children’s Hospital, Palo Alto, California, United States of America
- Department of Surgery, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
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Díaz-Valdés N, Comendador MA, Sierra LM. Mus308 processes oxygen and nitrogen ethylation DNA damage in germ cells of Drosophila. J Nucleic Acids 2010; 2010. [PMID: 20936147 PMCID: PMC2948884 DOI: 10.4061/2010/416364] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Revised: 07/27/2010] [Accepted: 09/02/2010] [Indexed: 11/22/2022] Open
Abstract
The D. melanogaster mus308 gene, highly conserved among higher eukaryotes, is implicated in the repair of cross-links and of O-ethylpyrimidine DNA damage, working in a DNA damage tolerance mechanism. However, despite its relevance, its possible role on the processing of different DNA ethylation damages is not clear. To obtain data on mutation frequency and on mutation spectra in mus308 deficient (mus308−) conditions, the ethylating agent diethyl sulfate (DES) was analysed in postmeiotic male germ cells. These data were compared with those corresponding to mus308 efficient conditions. Our results indicate that Mus308 is necessary for the processing of oxygen and N-ethylation damage, for the survival of fertilized eggs depending on the level of induced DNA damage, and for an influence of the DNA damage neighbouring sequence. These results support the role of mus308 in a tolerance mechanism linked to a translesion synthesis pathway and also to the alternative end-joinig system.
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Affiliation(s)
- Nancy Díaz-Valdés
- Área de Genética, Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (IUOPA), University of Oviedo, 33006 Oviedo, Spain
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Louro H, Faustino I, Dias A, Boavida MG, Silva MJ. Poly (ADP-ribose) polymerase-1 deficiency does not affect ethylnitrosourea mutagenicity in liver and testis of lacZ transgenic mice. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:322-329. [PMID: 20196134 DOI: 10.1002/em.20555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Poly (ADP-ribose) polymerase-1 (Parp1) has been implicated in DNA base excision repair, single- and double-strand break repair pathways, as well as in cell death by apoptosis or necrosis. We used Parp1(-/-) lacZ plasmid-based transgenic mice to investigate whether Parp1 deficiency influences the in vivo mutagenic and clastogenic response to the alkylating agent N-ethyl-N-Nitrosourea (ENU) in somatic and germ-cell tissues. The comparison of the lacZ mutant frequencies (MFs) between Parp1(+/+) and Parp1(-/-) mice showed that the ablation of Parp1 does not affect the spontaneous or ENU-induced MFs in liver and testis. In addition, the spectrum of the ENU-induced mutations was not dependent on the Parp1 status, given that similar spectra, consisting mostly of point mutations and a small fraction of deletions/insertions, wereobserved in organs of both Parp1(-/-) and Parp1(+/+) mice. Sequencing of point mutations revealed a consistent significant increase in A:T --> T:A base substitutions, typically induced by ENU. Overall, we observed that neither the frequency nor the spectrum of ENU-induced mutations demonstrated a specificity that could be attributed to the Parp1 impairment in mice organs. The analysis of micronucleus frequency in peripheral blood reticulocytes showed that ENU was clastogenic in both Parp1(-/-) and Parp1(+/+) mice and had a strong cytotoxic effect in Parp1(-/-) mice only. The present data suggest that, at a whole-organism level, Parp1-independent repair mechanisms may be operative in the removal of ENU-induced DNA lesions or that highly damaged cells may be preferentially committed to death when Parp1 is inactivated.
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Affiliation(s)
- Henriqueta Louro
- Departamento de Genética, Instituto Nacional de Saúde Dr. Ricardo Jorge (INSA), 1649-016 Lisboa, Portugal.
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Jang T, Sathy B, Hsu YH, Merchant M, Recht B, Chang C, Recht L. A distinct phenotypic change in gliomas at the time of magnetic resonance imaging detection. J Neurosurg 2008; 108:782-90. [DOI: 10.3171/jns/2008/108/4/0782] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Although gliomas remain refractory to treatment, it is not clear whether this characteristic is fixed at the time of its origin or develops later. The authors have been using a model of neurocarcinogenesis to determine whether a time exists during a glioma's evolution during which it is detectable but still curable, thus providing a justification for exploring the clinical merits of an early detection and treatment strategy. The authors recently reported the presence of 2 distinct cellular subsets, 1 expressing nestin and the other both glial fibrillary acidic protein (GFAP) and osteopontin (OPN), within all examined gliomas that developed after in utero exposure to ethylnitrosourea.
Methods
In this study, the authors used magnetic resonance (MR) imaging to assess when these 2 subpopulations appeared during glioma evolution.
Results
Using T2-weighted and diffusion-weighted MR imaging, the authors observed that gliomas grew exponentially once detected at rates that were location-dependent. Despite large differences in growth rates, however, they determined by correlating histochemistry with imaging in a second series of animals, that all lesions initially detected on T2-weighted images contained both subsets of cells. In contrast, lesions containing only nestin-positive cells, which appeared on average 40 days before detection on MR images, were not detected.
Conclusions
The sequential appearance of first the nestin-positive cells followed several weeks later by those expressing GFAP/OPN suggests that all gliomas arise through common early steps in this model. Furthermore, the authors hypothesize that the expression of OPN, a molecule associated with cancer aggressiveness, at the time of T2-weighted detection signals a time during glioma development when the lesion becomes refractory to treatment.
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Affiliation(s)
- Taichang Jang
- 1Department of Neurology, Stanford University Medical School, Stanford, California
| | - Binulal Sathy
- 2Institute of Biomedical Science, Academia Sinica, Nan-Kan, Taipei, Taiwan; and
| | - Yi-Hua Hsu
- 2Institute of Biomedical Science, Academia Sinica, Nan-Kan, Taipei, Taiwan; and
| | - Milton Merchant
- 1Department of Neurology, Stanford University Medical School, Stanford, California
| | - Benjamin Recht
- 3Media Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Chen Chang
- 2Institute of Biomedical Science, Academia Sinica, Nan-Kan, Taipei, Taiwan; and
| | - Lawrence Recht
- 1Department of Neurology, Stanford University Medical School, Stanford, California
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Hernando J, Alvarez L, Ferreiro JA, Sancho I, Comendador MA, Sierra LM. Female germ cell mutagenicity of model chemicals in Drosophila melanogaster: mechanistic information and analysis of repair systems. Mutat Res 2004; 545:59-72. [PMID: 14698417 DOI: 10.1016/j.mrfmmm.2003.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In spite of differences between female and male germ cells, and although both of them contribute to the gene pool of future generations, most germ cell mutagenicity studies in higher eukaryotes have been carried out on males. To study the response of female germ cells to mutagen/carcinogen exposure, the mutagenicity of two model chemicals like diethyl sulfate (DES) and hexamethylphosphoramide (HMPA), and the monofunctional methylating chemotherapeutic drug streptozotocin (STZ), has been analysed on repair efficient females of Drosophila melanogaster. Results previously obtained with N-ethyl-N-nitrosourea (ENU), another model chemical, have also been included in the analysis. The activity of bypass tolerance mechanism (BTM; represented by the mus308 locus) and nucleotide excision repair (NER) on the removal of oxygen and nitrogen ethylations was studied by determining DES mutagenicity in NER deficient females, comparing it with existing results for ENU, and by analysing both chemicals on BTM deficient females. Results indicate that (1) all chemicals are mutagenic on repair efficient females; (2) a measure of mutagenic activity ranked from the lowest DES to STZ, HMPA, and ENU as the highest. This order correlates with the repair of the respectively induced DNA damages, and with the mutagenic and carcinogenic potency of these compounds, considering the toxicity of cross-linking agents; (3) NER efficiently repairs nitrogen ethylation damage and seems to contribute to the processing of oxygen damage in female germ cells; and (4) BTM is involved on the processing of oxygen ethylation damage, whereas the results on nitrogen ethylation are not clear. Finally, these results indicate that differences between male and female germ cells affect the response to chemical exposure, and therefore demonstrate the necessity of analysing also female cells in germinal mutagenicity studies. In addition, these studies can provide important mechanistic information about germ cell chemical mutagenesis, and even when the analysis of oogonia is not possible, since all female germ cells are pre-meiotic, studies of oocytes could be a model for pre-meiotic cells.
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Affiliation(s)
- Julia Hernando
- Area de Genética, Dpto. Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, University of Oviedo, C/ Julián Clavería s/n, 33006 Oviedo, Spain
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