Signatures of TOP1 transcription-associated mutagenesis in cancer and germline

The mutational landscape is shaped by many processes. Genic regions are vulnerable to mutation but are preferentially protected by transcription-coupled repair1. In microorganisms, transcription has been demonstrated to be mutagenic2,3; however, the impact of transcription-associated mutagenesis remains to be established in higher eukaryotes4. Here we show that ID4—a cancer insertion–deletion (indel) mutation signature of unknown aetiology5 characterized by short (2 to 5 base pair) deletions —is due to a transcription-associated mutagenesis process. We demonstrate that defective ribonucleotide excision repair in mammals is associated with the ID4 signature, with mutations occurring at a TNT sequence motif, implicating topoisomerase 1 (TOP1) activity at sites of genome-embedded ribonucleotides as a mechanistic basis. Such TOP1-mediated deletions occur somatically in cancer, and the ID-TOP1 signature is also found in physiological settings, contributing to genic de novo indel mutations in the germline. Thus, although topoisomerases protect against genome instability by relieving topological stress6, their activity may also be an important source of mutations in the human genome.
We thank S. Jinks-Robertson for suggesting the traffic light reporter approach; H. Klein for guidance on fluctuation assays; R. van Boxtel for sharing sequencing data for MLH1-KO organoids; A. Bretherick, O. B. Reina and G. Kudla for advice on HygroR re-coding; staff at the IGC core services (L. Murphy, C. Nicol, C. Warnock, E. Freyer, S. Brown and J. Joseph), C. Logan, A. Fluteau, A. Robertson and the staff at Edinburgh Genomics for technical assistance; staff at Liverpool CLL Biobank (funded by Blood Cancer UK) for samples used to generate GEL WGS data; A. Ewing, C.-A. Martin, N. Hastie and W. Bickmore for discussions. Funding for this work: UK Medical Research Council Human Genetics Unit core grants (MC_UU_00007/5 to A.P.J., MC_UU_00007/11 to M.S.T.); Edinburgh Clinical Academic Track PhD programme (Wellcome Trust 204802/Z/16/Z) to T.C.W.; 2021 AACR-Amgen Fellowship in Clinical/Translational Cancer Research (grant number 21-40-11-NADE) to F.N.; a CRUK Brain Tumour Centre of Excellence Award (C157/A27589) to M.D.N.; EKFS research grant (2019_A09), Wilhelm Sander-Stiftung (2019.046.1) to K.A., CRUK programme grant (C20807/A2864) to T.S.; La Caixa Foundation (CLLEvolution-LCF/PR/HR17/52150017, Health Research 2017 Program HR17-00221) to E.C.; E.C. is an Academia Researcher of the Institució Catalana de Recerca i Estudis Avançats of the Generalitat de Catalunya. Edinburgh Genomics is partly supported by NERC (R8/H10/56), MRC (MR/K001744/1) and BBSRC (BB/J004243/1). This research was made possible through access to the data and findings generated by the 100,000 Genomes Project. The 100,000 Genomes Project is managed by Genomics England Limited (a wholly owned company of the Department of Health and Social Care). The 100,000 Genomes Project is funded by the National Institute for Health Research and NHS England. The Wellcome Trust, Cancer Research UK and the Medical Research Council have also funded research infrastructure. The 100,000 Genomes Project uses data provide
Peer Reviewed
"Article signat per 22 autors/es: Martin A. M. Reijns, David A. Parry, Thomas C. Williams, Ferran Nadeu, Rebecca L. Hindshaw, Diana O. Rios Szwed, Michael D. Nicholson, Paula Carroll, Shelagh Boyle, Romina Royo, Alex J. Cornish, Hang Xiang, Kate Ridout, The Genomics England Research Consortium, Colorectal Cancer Domain UK 100,000 Genomes Project, Anna Schuh, Konrad Aden, Claire Palles, Elias Campo, Tatjana Stankovic, Martin S. Taylor & Andrew P. Jackson "
Postprint (published version)