Search results for " mismatch"

DNA methylation changes and somatic mutations as tumorigenic events in Lynch syndrome-associated adenomas retaining mismatch repair protein expression

2018

Background: DNA mismatch repair (MMR) defects are a major factor in colorectal tumorigenesis in Lynch syndrome (LS) and 15% of sporadic cases. Some adenomas from carriers of inherited MMR gene mutations have intact MMR protein expression implying other mechanisms accelerating tumorigenesis. We determined roles of DNA methylation changes and somatic mutations in cancer-associated genes as tumorigenic events in LS-associated colorectal adenomas with intact MMR. Methods: We investigated 122 archival colorectal specimens of normal mucosae, adenomas and carcinomas from 57 LS patients. MMR-deficient (MMR-D, n 49) and MMR-proficient (MMR-P, n 18) adenomas were of particular interest and were inter…

The shared frameshift mutation landscape of microsatellite-unstable cancers suggests immunoediting during tumor evolution

2020

The immune system can recognize and attack cancer cells, especially those with a high load of mutation-induced neoantigens. Such neoantigens are abundant in DNA mismatch repair (MMR)-deficient, microsatellite-unstable (MSI) cancers. MMR deficiency leads to insertion/deletion (indel) mutations at coding microsatellites (cMS) and to neoantigen-inducing translational frameshifts. Here, we develop a tool to quantify frameshift mutations in MSI colorectal and endometrial cancer. Our results show that frameshift mutation frequency is negatively correlated to the predicted immunogenicity of the resulting peptides, suggesting counterselection of cell clones with highly immunogenic frameshift peptid…

Prognostic value of methylator phenotype in stage III colon cancer treated with oxaliplatin-based adjuvant chemotherapy

2017

Abstract Purpose: There are conflicting results concerning the prognostic value of the CpG island methylator phenotype (CIMP) in patients with nonmetastatic colon cancer. We studied this phenotype in stage III colon cancer characterized for mismatch repair (MMR), RAS, and BRAF status, and treated with adjuvant FOLFOX-based regimen. Experimental Design: Tumor samples of 1,907 patients enrolled in the PETACC-8 adjuvant phase III trial were analyzed. The method used was methylation-specific PCR, where CIMP+ status was defined by methylation of at least 3 of 5 following genes: IGF2, CACNA1G, NEUROG1, SOCS1, and RUNX3. Association between CIMP status and overall survival (OS), disease-free survi…

Associations of Pathogenic Variants in MLH1, MSH2, and MSH6 With Risk of Colorectal Adenomas and Tumors and With Somatic Mutations in Patients With L…

2020

Contains fulltext : 220040.pdf (Publisher’s version ) (Closed access) BACKGROUND & AIMS: Lynch syndrome is caused by variants in DNA mismatch repair (MMR) genes and associated with an increased risk of colorectal cancer (CRC). In patients with Lynch syndrome, CRCs can develop via different pathways. We studied associations between Lynch syndrome-associated variants in MMR genes and risks of adenoma and CRC and somatic mutations in APC and CTNNB1 in tumors in an international cohort of patients. METHODS: We combined clinical and molecular data from 3 studies. We obtained clinical data from 2747 patients with Lynch syndrome associated with variants in MLH1, MSH2, or MSH6 from Germany, the Net…

Does breast carcinoma belong to the Lynch syndrome tumor spectrum? : Somatic mutational profiles vs. ovarian and colorectal carcinomas

2020

// Noora K. Porkka 1 , Alisa Olkinuora 1 , Teijo Kuopio 2 , 3 , Maarit Ahtiainen 4 , Samuli Eldfors 5 , Henrikki Almusa 5 , Jukka-Pekka Mecklin 6 , 7 , 8 and Paivi Peltomaki 1 1 Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland 2 Department of Pathology, Jyvaskyla Central Hospital, Jyvaskyla, Finland 3 Department of Biological and Environmental Science, University of Jyvaskyla, Jyvaskyla, Finland 4 Department of Education and Research, Jyvaskyla Central Hospital and University of Eastern Finland, Jyvaskyla, Finland 5 Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland 6 Faculty of Sport and Health Sciences, University of J…

HSP110 T17 simplifies and improves the microsatellite instability testing in patients with colorectal cancer

2016

IF 5.65; International audience; Background Every colorectal cancer (CRC) patient should be tested for microsatellite instability (MSI, a marker for defective DNA mismatch repair) as a first screen for Lynch syndrome (LS). In this study, we investigated whether it may be possible to improve the detection of MSI in CRC. We examined whether the HT17 DNA repeat (critical for correct splicing of the chaperone HSP110) might constitute a superior marker for diagnosis of the MSI phenotype in patients with CRC compared with the standard panel of markers (pentaplex).Methods The HT17 polymorphism was analysed in germline DNA from 1037 multi-ethnic individuals. We assessed its sensitivity and specific…

Risk-reducing hysterectomy and bilateral salpingo-oophorectomy in female heterozygotes of pathogenic mismatch repair variants: a Prospective Lynch Sy…

2021

Abstract Purpose To determine impact of risk-reducing hysterectomy and bilateral salpingo-oophorectomy (BSO) on gynecological cancer incidence and death in heterozygotes of pathogenic MMR ( path_MMR ) variants. Methods The Prospective Lynch Syndrome Database was used to investigate the effects of gynecological risk-reducing surgery (RRS) at different ages. Results Risk-reducing hysterectomy at 25 years of age prevents endometrial cancer before 50 years in 15%, 18%, 13%, and 0% of path_MLH1 , path_MSH2 , path_MSH6 , and path_PMS2 heterozygotes and death in 2%, 2%, 1%, and 0%, respectively. Risk-reducing BSO at 25 years of age prevents ovarian cancer before 50 years in 6%, 11%, 2%, and 0% and…

The Role of Hydrophobic Mismatch on Transmembrane Helix Dimerization in Living Cells

2019

The sharedneoantigen landscape of MSI cancers reflects immunoediting during tumor evolution

2019

AbstractThe immune system can recognize and attack cancer cells, especially those with a high load of mutation-inducedneoantigens. Suchneoantigens are particularly abundant in DNA mismatch repair (MMR)-deficient, microsatellite-unstable (MSI) cancers. MMR deficiency leads to insertion/deletion (indel) mutations at coding microsatellites (cMS) and toneoantigen-inducing translational frameshifts. The abundance of mutationalneoantigens renders MSI cancers sensitive to immune checkpoint blockade. However, the neoantigen landscape of MMR-deficient cancers has not yet been systematically mapped. In the present study, we used a novel tool to monitorneoantigen-inducing indel mutations in MSI colore…

Visual mismatch negativity (vMMN): A review and meta-analysis of studies in psychiatric and neurological disorders

2016

The visual mismatch negativity (vMMN) response is an event-related potential (ERP) component, which is automatically elicited by events that violate predictions based on prior events. VMMN experiments use visual stimulus repetition to induce predictions, and vMMN is obtained by subtracting the response to rare unpredicted stimuli from those to frequent stimuli. One increasingly popular interpretation of the mismatch response postulates that vMMN, similar to its auditory counterpart (aMMN), represents a prediction error response generated by cortical mechanisms forming probabilistic representations of sensory signals. Here we discuss the physiological and theoretical basis of vMMN and review…