journal contribution
posted on 2023-03-31, 00:40 authored by Johanna Kondelin, Alexandra E. Gylfe, Sofie Lundgren, Tomas Tanskanen, Jiri Hamberg, Mervi Aavikko, Kimmo Palin, Heikki Ristolainen, Riku Katainen, Eevi Kaasinen, Minna Taipale, Jussi Taipale, Laura Renkonen-Sinisalo, Heikki Järvinen, Jan Böhm, Jukka-Pekka Mecklin, Pia Vahteristo, Sari Tuupanen, Lauri A. Aaltonen, Esa Pitkänen The median coverage at different genes in the MiSeq data. frequency and significance in exome and MiSeq data (per microsatellite and per gene) as well as the NAFs in the MiSeq data.
Funding
Academy of Finland
Jane and Aatos Erkko Foundation
Biomedicum Helsinki Foundation
Otto Malm Foundation
Ida Montin Foundation
Orion-Farmos Research Foundation
Oskar Öflunds Stiftelse
Maud Kuistila Memorial Foundation
University of Helsinki
NIASC
NordForsk
History
ARTICLE ABSTRACT
Approximately 15% of colorectal cancers exhibit microsatellite instability (MSI), which leads to accumulation of large numbers of small insertions and deletions (indels). Genes that provide growth advantage to cells via loss-of-function mutations in microsatellites are called MSI target genes. Several criteria to define these genes have been suggested, one of them being simple mutation frequency. Microsatellite mutation rate, however, depends on the length and nucleotide context of the microsatellite. Therefore, assessing the general impact of mismatch repair deficiency on the likelihood of mutation events is paramount when following this approach. To identify MSI target genes, we developed a statistical model for the somatic background indel mutation rate of microsatellites to assess mutation significance. Exome sequencing data of 24 MSI colorectal cancers revealed indels at 54 million mononucleotide microsatellites of three or more nucleotides in length. The top 105 microsatellites from 71 genes were further analyzed in 93 additional MSI colorectal cancers. Mutation significance and estimated clonality of mutations determined the most likely MSI target genes to be the aminoadipate-semialdehyde dehydrogenase AASDH and the solute transporter SLC9A8. Our findings offer a systematic profiling of the somatic background mutation rate in protein-coding mononucleotide microsatellites, allowing a full cataloging of the true targets of MSI in colorectal cancer. Cancer Res; 77(15); 4078–88. ©2017 AACR.
