ATM orchestrates the DNA-damage response to counter toxic non-homologous end-joining at broken replication forks

• Published in: Nature communications Vol. 10; no. 1; pp. 87 - 18
• Main Authors: Balmus, Gabriel, Pilger, Domenic, Coates, Julia, Demir, Mukerrem, Sczaniecka-Clift, Matylda, Barros, Ana C., Woods, Michael, Fu, Beiyuan, Yang, Fengtang, Chen, Elisabeth, Ostermaier, Matthias, Stankovic, Tatjana, Ponstingl, Hannes, Herzog, Mareike, Yusa, Kosuke, Martinez, Francisco Munoz, Durant, Stephen T., Galanty, Yaron, Beli, Petra, Adams, David J., Bradley, Allan, Metzakopian, Emmanouil, Forment, Josep V., Jackson, Stephen P.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.01.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 13/100; 13/106; 14; 49; 631/208; 631/67; 631/80; 692/4028/67/1059/2326; 82/58; Adenosine diphosphate; Animals; Antineoplastic Agents - pharmacology; Antineoplastic Agents - therapeutic use; Ataxia Telangiectasia Mutated Proteins - genetics; Ataxia Telangiectasia Mutated Proteins - metabolism; BRCA1 protein; BRCA1 Protein - metabolism; Breast cancer; Cell Line, Tumor; Cell Survival - genetics; Chemotherapy; CRISPR; CRISPR-Cas Systems - genetics; Damage; Deoxyribonucleic acid; Disruption; DNA; DNA biosynthesis; DNA Breaks, Double-Stranded - drug effects; DNA damage; DNA End-Joining Repair - genetics; DNA Ligase ATP - metabolism; DNA Replication - drug effects; DNA Replication - genetics; DNA topoisomerase; Drug Resistance, Neoplasm - genetics; Female; Genetic suppression; Genomes; Homologous recombination; Homology; Humanities and Social Sciences; Humans; Hypersensitivity; Inhibitors; LIG4 protein; Mice; Mice, Inbred NOD; Mice, Knockout; Mouse Embryonic Stem Cells; multidisciplinary; Mutation; Neoplasms, Experimental - drug therapy; Neoplasms, Experimental - genetics; Neoplasms, Experimental - pathology; Non-homologous end joining; Phthalazines - pharmacology; Phthalazines - therapeutic use; Piperazines - pharmacology; Piperazines - therapeutic use; Poly(ADP-ribose) polymerase; Replication; Replication forks; Ribose; Science; Science (multidisciplinary); Screens; Topotecan; Topotecan - pharmacology; Topotecan - therapeutic use; Toxicity; Tumor suppressor genes
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-07729-2

Mutations in the ATM tumor suppressor gene confer hypersensitivity to DNA-damaging chemotherapeutic agents. To explore genetic resistance mechanisms, we performed genome-wide CRISPR-Cas9 screens in cells treated with the DNA topoisomerase I inhibitor topotecan. Thus, we here establish that inactivating terminal components of the non-homologous end-joining (NHEJ) machinery or of the BRCA1-A complex specifically confer topotecan resistance to ATM-deficient cells. We show that hypersensitivity of ATM -mutant cells to topotecan or the poly-(ADP-ribose) polymerase (PARP) inhibitor olaparib reflects delayed engagement of homologous recombination at DNA-replication-fork associated single-ended double-strand breaks (DSBs), allowing some to be subject to toxic NHEJ. Preventing DSB ligation by NHEJ, or enhancing homologous recombination by BRCA1-A complex disruption, suppresses this toxicity, highlighting a crucial role for ATM in preventing toxic LIG4-mediated chromosome fusions. Notably, suppressor mutations in ATM -mutant backgrounds are different to those in BRCA1 -mutant scenarios, suggesting new opportunities for patient stratification and additional therapeutic vulnerabilities for clinical exploitation. Mutations in the ATM tumor suppressor gene confer hypersensitivity to DNA-damaging chemotherapeutic agents. Here, the authors provide evidence that these hypersensitivities reflect a crucial role for ATM at damaged replication forks being to prevent toxic DNA end-joining leading to chromosome fusions and cell death.