Project description:Only a small proportion of cases suspected to have Lynch Syndrome (LS) can be explained by mutation in the mismatch repair (MMR) genes. This study aimed to identify rare CNVs that may contribute to an increased risk for hereditary colorectal cancer in patients with MMR proficiency.
Project description:Only a small proportion of cases suspected to have Lynch Syndrome (LS) can be explained by mutation in the mismatch repair (MMR) genes. This study aimed to identify rare CNVs that may contribute to an increased risk for hereditary colorectal cancer in patients with MMR proficiency.
Project description:Lynch syndrome, caused by germline heterozygous mutations of the DNA mismatch repair genes MLH1, MSH2, MSH6 and PMS2, or deletions affecting the EPCAM gene upstream of MSH2, is characterized by a predisposition to early-onset colorectal and additional extracolonic cancers. An alternative but rare cause of Lynch syndrome is a constitutional epimutation of MLH1, which is characterized by promoter methylation and transcriptional silencing of a single allele in normal tissues. Worldwide, five families with autosomal dominant transmission of a constitutional MLH1 epimutation linked to an MLH1 haplotype with two single nucleotide variants (c.-27C>A and c.85G>T) have been identified. Array-based genotyping using Affymetrix SNP 6.0 data in four of these families revealed a shared haplotype extending across a ≤2.6 Mb region of chromosome 3p22 encompassing MLH1 and additional flanking genes, indicating common ancestry. Genomic DNA from 5 carriers of the c.-27C>A and c.85G>T variants was hybridized on Affymetrix SNP6.0 array according to manufacturer's procedures
Project description:Lynch syndrome and Familial colorectal cancer type X (FCCTX) are clinically diagnosed using the same criteria, but genomic differences exist between these two groups and the genomic profiles share similarities with their sporadic counterparts, mismatch repair (MMR) deficient and proficient tumors, respectively. Array-based comparative genomic hybridization was performed on 91 tumors, comprising 23 Lynch syndrome (AH), 23 FCCTX (AA), 23 sporadic MMR deficient (AM) and 22 sporadic MMR proficient tumors, in order to identify differences between Lynch syndrome and FCCTX.
Project description:Colorectal carcinomas arising in the context of Lynch syndrome, the most common inherited cancer syndrome, typically show deficiency of the DNA MMR (mismatch repair) system. Lack of functional MMR leads to accumulation of frameshift mutations at micosatellites (microsatellite instability, MSI). High load of highly immunogenic tumor-specific frameshift neoantigens results in strong immune response against Lynch syndrome MSI cancers. Previous studies have shown systemic immune responses against frameshift neoantigens in Lynch syndrome carriers long before tumor manifestation. In the present study, we analyzed the immune profile of normal colorectal mucosa in Lynch syndrome carriers without current or previous cancer history and in Lynch syndrome colorectal cancer patients, as well as of Lynch syndrome colorectal carcinomas. The unsupervised cluster analysis of gene expression data revealed a sharp differentiation between normal mucosa from Lynch syndrome individuals with and without manifest cancer as well as between normal mucosa in general and Lynch syndrome cancer tissue. Deconvolution analysis for predicting the prevalence of immune cell population among the three groups revealed 10 out of 14 investigated populations to be significantly different between the three tissue types (FDR=10%). In contrast to normal mucosa samples, tumor tissue showed overrepresentation of immune-suppressive cell populations, such as regulatory T cells and neutrophils. Taken together with the quantitative T cell density analysis on the basis of immunohistochemical T cell stainings, our data show strong immune infiltration of the normal colorectal mucosa in Lynch syndrome individuals even in the absence of a manifest cancer.
Project description:Lynch syndrome, caused by germline heterozygous mutations of the DNA mismatch repair genes MLH1, MSH2, MSH6 and PMS2, or deletions affecting the EPCAM gene upstream of MSH2, is characterized by a predisposition to early-onset colorectal and additional extracolonic cancers. An alternative but rare cause of Lynch syndrome is a constitutional epimutation of MLH1, which is characterized by promoter methylation and transcriptional silencing of a single allele in normal tissues. Worldwide, five families with autosomal dominant transmission of a constitutional MLH1 epimutation linked to an MLH1 haplotype with two single nucleotide variants (c.-27C>A and c.85G>T) have been identified. Array-based genotyping using Affymetrix SNP 6.0 data in four of these families revealed a shared haplotype extending across a ≤2.6 Mb region of chromosome 3p22 encompassing MLH1 and additional flanking genes, indicating common ancestry.
Project description:DNA mismatch repair deficiency (MMRD) drives microsatellite instability (MSI). Cells with MSI accumulate numerous frameshift mutations. Frameshift mutations affecting cancer-related genes may promote tumorigenesis and, therefore, are shared among independently arising MSI tumors. Consequently, such recurrent frameshift mutations can give rise to shared immunogenic frameshift peptides (FSPs) that represent ideal candidates for a vaccine against MSI cancer. Pathogenic germline variants of mismatch repair genes cause Lynch syndrome (LS), a hereditary cancer syndrome affecting approximately 20-25 million individuals worldwide. LS individuals are at high risk of developing MSI cancer. Previously, we demonstrated safety and immunogenicity of an FSP-based vaccine in a Phase I/IIa clinical trial. However, the cancer-preventive effect of FSP vaccination in the scenario of LS has not been demonstrated so far.
Project description:Lynch syndrome and Familial colorectal cancer type X (FCCTX) are clinically diagnosed using the same criteria, but genomic differences exist between these two groups and the genomic profiles share similarities with their sporadic counterparts, mismatch repair (MMR) deficient and proficient tumors, respectively.
