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León TE, Rapoz-D'Silva T, Bertoli C, Rahman S, Magnussen M, Philip B, Farah N, Richardson SE, Ahrabi S, Guerra-Assunção JA, Gupta R, Nacheva EP, Henderson S, Herrero J, Linch DC, de Bruin RAM, Mansour MR. EZH2-Deficient T-cell Acute Lymphoblastic Leukemia Is Sensitized to CHK1 Inhibition through Enhanced Replication Stress. Cancer Discov 2020; 10:998-1017. [PMID: 32349972 PMCID: PMC7611258 DOI: 10.1158/2159-8290.cd-19-0789] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 03/13/2020] [Accepted: 04/24/2020] [Indexed: 11/16/2022]
Abstract
Loss-of-function mutations of EZH2, the enzymatic component of PRC2, have been associated with poor outcome and chemotherapy resistance in T-cell acute lymphoblastic leukemia (T-ALL). Using isogenic T-ALL cells, with and without CRISPR/Cas9-induced EZH2-inactivating mutations, we performed a cell-based synthetic lethal drug screen. EZH2-deficient cells exhibited increased sensitivity to structurally diverse inhibitors of CHK1, an interaction that could be validated genetically. Furthermore, small-molecule inhibition of CHK1 had efficacy in delaying tumor progression in isogenic EZH2-deficient, but not EZH2 wild-type, T-ALL cells in vivo, as well as in a primary cell model of PRC2-mutant ALL. Mechanistically, EZH2 deficiency resulted in a gene-expression signature of immature T-ALL cells, marked transcriptional upregulation of MYCN, increased replication stress, and enhanced dependency on CHK1 for cell survival. Finally, we demonstrate this phenotype is mediated through derepression of a distal PRC2-regulated MYCN enhancer. In conclusion, we highlight a novel and clinically exploitable pathway in high-risk EZH2-mutated T-ALL. SIGNIFICANCE: Loss-of-function mutations of PRC2 genes are associated with chemotherapy resistance in T-ALL, yet no specific therapy for this aggressive subtype is currently clinically available. Our work demonstrates that loss of EZH2 activity leads to MYCN-driven replication stress, resulting in increased sensitivity to CHK1 inhibition, a finding with immediate clinical relevance.This article is highlighted in the In This Issue feature, p. 890.
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Affiliation(s)
- Theresa E León
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Tanya Rapoz-D'Silva
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Cosetta Bertoli
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Sunniyat Rahman
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Michael Magnussen
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Brian Philip
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Nadine Farah
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Simon E Richardson
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Sara Ahrabi
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | | | - Rajeev Gupta
- Stem Cell Laboratory, UCL Cancer Institute, University College London, London, United Kingdom
| | - Elisabeth P Nacheva
- Health Service Laboratories LLP, UCL Cancer Institute, London, United Kingdom
| | - Stephen Henderson
- Bill Lyons Informatics Centre, UCL Cancer Institute, University College London, London, United Kingdom
| | - Javier Herrero
- Bill Lyons Informatics Centre, UCL Cancer Institute, University College London, London, United Kingdom
| | - David C Linch
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Robertus A M de Bruin
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Marc R Mansour
- Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom.
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