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Zou X, Koh GCC, Nanda AS, Degasperi A, Urgo K, Roumeliotis TI, Agu CA, Badja C, Momen S, Young J, Amarante TD, Side L, Brice G, Perez-Alonso V, Rueda D, Gomez C, Bushell W, Harris R, Choudhary JS, Jiricny J, Skarnes WC, Nik-Zainal S. A systematic CRISPR screen defines mutational mechanisms underpinning signatures caused by replication errors and endogenous DNA damage. Nat Cancer 2021; 2:643-657. [PMID: 34164627 PMCID: PMC7611045 DOI: 10.1038/s43018-021-00200-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 03/17/2021] [Indexed: 02/02/2023]
Abstract
Mutational signatures are imprints of pathophysiological processes arising through tumorigenesis. We generated isogenic CRISPR-Cas9 knockouts (Δ) of 43 genes in human induced pluripotent stem cells, cultured them in the absence of added DNA damage, and performed whole-genome sequencing of 173 subclones. ΔOGG1, ΔUNG, ΔEXO1, ΔRNF168, ΔMLH1, ΔMSH2, ΔMSH6, ΔPMS1, and ΔPMS2 produced marked mutational signatures indicative of being critical mitigators of endogenous DNA modifications. Detailed analyses revealed mutational mechanistic insights, including how 8-oxo-dG elimination is sequence-context-specific while uracil clearance is sequence-context-independent. Mismatch repair (MMR) deficiency signatures are engendered by oxidative damage (C>A transversions), differential misincorporation by replicative polymerases (T>C and C>T transitions), and we propose a 'reverse template slippage' model for T>A transversions. ΔMLH1, ΔMSH6, and ΔMSH2 signatures were similar to each other but distinct from ΔPMS2. Finally, we developed a classifier, MMRDetect, where application to 7,695 WGS cancers showed enhanced detection of MMR-deficient tumors, with implications for responsiveness to immunotherapies.
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Affiliation(s)
- Xueqing Zou
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
- Wellcome Sanger Institute, Hinxton, UK
| | - Gene Ching Chiek Koh
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
- Wellcome Sanger Institute, Hinxton, UK
| | - Arjun Scott Nanda
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
| | - Andrea Degasperi
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
- Wellcome Sanger Institute, Hinxton, UK
| | | | | | | | - Cherif Badja
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
- Wellcome Sanger Institute, Hinxton, UK
| | - Sophie Momen
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
| | - Jamie Young
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Tauanne Dias Amarante
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
| | - Lucy Side
- UCL Institute for Women's Health, Great Ormond Street Hospital, London, UK
- Wessex Clinical Genetics Service, Princess Anne Hospital, Southampton, UK
| | - Glen Brice
- Southwest Thames Regional Genetics Service, St George's University of London, London, UK
| | - Vanesa Perez-Alonso
- Pediatrics Department, Doce de Octubre University Hospital, i+12 Research Institute, Madrid, Spain
| | - Daniel Rueda
- Hereditary Cancer Laboratory, Doce de Octubre University Hospital, i+12 Research Institute, Madrid, Spain
| | | | | | - Rebecca Harris
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- Wellcome Sanger Institute, Hinxton, UK
| | - Jyoti S Choudhary
- The Institute of Cancer Research, Chester Beatty Laboratories, London, UK
| | - Josef Jiricny
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - William C Skarnes
- Wellcome Sanger Institute, Hinxton, UK
- William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Serena Nik-Zainal
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge, UK.
- MRC Cancer Unit, University of Cambridge, Cambridge, UK.
- Wellcome Sanger Institute, Hinxton, UK.
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Zou X, Koh G, Nanda S, Degasperi A, Urgo K, Bushell W, Agu C, Perez-Alonso V, Rueda D, Foreman J, Harris R, Jiricny J, Skarnes B, Nik-Zainal S. Abstract 4887: Direct mutational consequences of CRISPR-cas9 gene-edited DNA repair genes. Cancer Res 2020. [DOI: 10.1158/1538-7445.am2020-4887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Cancer whole-genome sequencing has revealed characteristic mutational signatures associated with defective DNA repair that underpin human genetic diseases. To define the direct mutagenic effects of DNA repair deficiency at the genome-wide level, we investigate mutational signatures generated by CRISPR-Cas9-based knockouts of 42 genes involved in DNA repair/replication using a human-induced pluripotent stem cell line. Knockouts (Δ) of nine DNA repair genes reveal substitution/indel mutational signatures. Notably, dissection of signatures of defective mismatch repair (MMR) uncovers gene-specific characteristics including distinguishing features of ΔMLH1, ΔMSH2, and ΔMSH6 from ΔPMS2. This gene-specificity is also exhibited by hIPSCs derived from patients with autosomal recessive Constitutional Mismatch Repair Deficiency (CMMRD) that carry biallelic germline mutations of MMR genes. Furthermore, gene-specificity manifests in whole genome sequenced primary human cancers. Additionally, detailed analyses reveal putative sources of endogenous DNA damage that contribute to MMR signatures, including guanine oxidation, errors of DNA polymerases and reversed template slippage or double slippage. Finally, we find that using all mutational signatures of MMR-deficiency as identified in this study results in improved sensitivity and specificity in classifying MMR-deficient tumors, critical for accurate patient stratification for therapeutic intervention.
Citation Format: Xueqing Zou, Gene Koh, Scott Nanda, Andrea Degasperi, Katie Urgo, Wendy Bushell, Chukwuma Agu, Vanesa Perez-Alonso, Daniel Rueda, Julia Foreman, Rebecca Harris, Josef Jiricny, Bill Skarnes, Serena Nik-Zainal. Direct mutational consequences of CRISPR-cas9 gene-edited DNA repair genes [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4887.
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Affiliation(s)
- Xueqing Zou
- 1University of Cambridge, Cambridge, United Kingdom
| | - Gene Koh
- 1University of Cambridge, Cambridge, United Kingdom
| | - Scott Nanda
- 1University of Cambridge, Cambridge, United Kingdom
| | | | - Katie Urgo
- 2Sanger Institute, Cambridge, United Kingdom
| | | | | | | | - Daniel Rueda
- 3Doce de Octubre University Hospital, Madrid, Spain
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