Journal Article DKFZ-2025-00594

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Lower degree of microsatellite instability in colorectal carcinomas from MSH6-associated Lynch syndrome patients.

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2025
Nature Publishing Group London

Modern pathology 38(7), 100757 () [10.1016/j.modpat.2025.100757]
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Abstract: Numerous observational and molecular studies focusing on Lynch syndrome (LS) have revealed significant variation in the phenotype and molecular characteristics among carriers of pathogenic variants in mismatch repair genes (path_MMR). Recently, we demonstrated that colorectal carcinomas in path_MSH6 carriers exhibit fewer insertion/deletion mutations compared to CRCs from other MMR groups, raising the question of whether MSH6-mutated CRCs might display a relatively lower degree of microsatellite instability (MSI). Mutations at twenty coding microsatellites (cMS) were analyzed in 39 MSH6-, 18 MLH1-, 16 MSH2- and 22 PMS2-mutated CRCs and 35 sporadic MSI CRCs, and mutation frequencies and mutant allele ratios were compared among the different MMR-deficient groups. Considering factors such as HLA-A*02:01 type, B2M status, and the anticipated immunogenicity of frameshift peptides derived from cMS mutations, the identified cMS mutation profiles of MSH6-mutated CRCs were further investigated to assess their potential impact on immunotherapeutic strategies. MSH6-mutated CRCs exhibited lower mutation frequencies and mutant allele ratios across most cMS. Variation in cMS mutation patterns was observed both between different tumor regions and between tumor tissue and adjacent adenomatous tissue. The cMS mutations in MSH6-mutated CRCs demonstrated inverse correlations with the predicted immunogenicity of the resulting frameshift peptides, which may suggest negative selection of cell clones bearing highly immunogenic frameshift peptides. Overall, MSH6-mutated CRCs display a relatively lower degree of MSI and represent a biologically distinct subgroup of LS-associated CRCs. This lower MSI level may implicate an altered immune response compared to other MSI CRCs, which could have theoretical implications for the success of immunotherapy in MSH6-mutated CRCs. Future studies should carefully evaluate this possibility. If confirmed, these results would reinforce the notion of classifying LS as distinct syndromes associated with specific MMR genes.

Keyword(s): Lynch syndrome ; coding microsatellites ; colorectal cancer ; frameshift peptides ; microsatellite instability ; mismatch repair

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Note: #LA:D470# / Volume 38, Issue 7, July 2025, 100757

Contributing Institute(s):
  1. KKE Angewandte Tumorbiologie (D470)
Research Program(s):
  1. 314 - Immunologie und Krebs (POF4-314) (POF4-314)

Appears in the scientific report 2025
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Medline ; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Clinical Medicine ; Current Contents - Life Sciences ; DEAL Springer ; Essential Science Indicators ; IF >= 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection
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 Record created 2025-03-24, last modified 2025-04-11



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