Validation of an in Vitro Mismatch Repair Assay Used in the Functional Characterization of Mismatch Repair Variants

Publication date: Available online 25 December 2019Source: The Journal of Molecular DiagnosticsAuthor(s): Maribel González-Acosta, Inga Hinrichsen, Anna Fernández, Conxi Lázaro, Marta Pineda, Guido Plotz, Gabriel CapelláA significant proportion of DNA-mismatch repair (MMR) variants are classified as of unknown significance, precluding diagnosis. The in vitro MMR assay is used to assess their MMR capability, likely the most important function of an MMR protein. However, the robustness of the assay, crucial for its use in the clinical setting, has been rarely evaluated. The aim of the present work was to validate an in vitro MMR assay approach to the functional characterization of MMR variants, as a first step to meeting quality standards of diagnostic laboratories. The MMR assay was optimized by testing a variety of reagents and experimental conditions. Reference materials and standard operating procedures were established. To determine the intra- and interexperimental variability of the assay and its reproducibility among centers, independent transfections of six previously characterized DNA-mismatch repair protein MLH1 variants were performed in two independent laboratories. Reagents and conditions optimal for performing the in vitro MMR assay were determined. The validated assay demonstrated no significant intra- or interexperimental variability and good reproducibility between centers. We set up a robust in vitro MMR assay th...
Source: The Journal of Molecular Diagnostics - Category: Pathology Source Type: research

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Authors: Blosser WD, Dempsey JA, McNulty AM, Rao X, Ebert PJ, Lowery CD, Iversen PW, Webster YW, Donoho GP, Gong X, Merzoug FF, Buchanan S, Boehnke K, Yu C, You XT, Beckmann RP, Wu W, McNeely SC, Lin AB, Martinez R Abstract The combined influence of oncogenic drivers, genomic instability, and/or DNA damage repair deficiencies increases replication stress in cancer. Cells with high replication stress rely on the upregulation of checkpoints like those governed by CHK1 for survival. Previous studies of the CHK1 inhibitor prexasertib demonstrated activity across multiple cancer types. Therefore, we sought to (1) identi...
Source: Oncotarget - Category: Cancer & Oncology Tags: Oncotarget Source Type: research
Authors: Melloul S, Mosnier JF, Masliah-Planchon J, Lepage C, Le Malicot K, Gornet JM, Edeline J, Dansette D, Texereau P, Delattre O, Laurent Puig P, Taieb J, J-F E Abstract SMARCB1 is a tumor suppressor gene, which is part of SWI/SNF complex involved in transcriptional regulation. Recently, loss of SMARCB1 expression has been reported in gastrointestinal carcinomas. Our purpose was to evaluate the incidence and prognostic value of SMARCB1 loss in colon carcinoma (CC). Patients with stage III CC (n= 1695), and a second cohort of 23 patients with poorly differentiated CC were analyzed. Immunohistochemistry for SMARC...
Source: Cancer Biomarkers - Category: Cancer & Oncology Tags: Cancer Biomark Source Type: research
This article presents her outstanding character and most important lines of research. The focus of her studies covered alkylative and oxidative damage to DNA bases, in particular mutagenic and carcinogenic properties of purines with an open imidazole ring and 8-oxo-7,8-dihydroguanine (8-oxoGua). They also included analysis of mutagenic properties and pathways for the repair of DNA adducts of lipid peroxidation (LPO) products arising in large quantities during inflammation. Professor Tudek did all of this in the hope of deciphering the mechanisms of DNA damage removal, in particular by the base excision repair (BER) pathway...
Source: Mutation Research Genetic Toxicology and Environmental Mutagenesis - Category: Genetics & Stem Cells Source Type: research
Conclusions: Niraparib effectively radiosensitizes HNSCCs with a greater benefit seen in HPV(-). HPV status also plays a role in response to MK-8776 or MK-1775 when combined with niraparib due to differences in DNA repair mechanisms. This study suggests that using cell cycle abrogators in combination with PARP inhibitors may be a beneficial treatment option in HNSCC, but also emphasizes the importance of HPV status when considering effective treatment strategies. PMID: 32073931 [PubMed - as supplied by publisher]
Source: International Journal of Radiation Biology - Category: Radiology Tags: Int J Radiat Biol Source Type: research
AbstractAnti ‐programmed cell death 1 (PD‐1) and its ligand (PD‐L1) has emerged as a novel immunotherapy for non‐small cell lung cancer (NSCLC). However, the proportion of patients who may benefit from immunotherapy is limited and the factors sensitive or resistant to immunotherapy are not completely cle ar. Therefore, to identify reliable biomarkers as predictors of clinical response and resistance to anti‐PD‐1/PD‐L1 therapies have become increasingly important. Here, we report a case of a patient with bone metastatic NSCLC, who achieved a pathologic complete response after preoperative pembr olizumab treatm...
Source: Thoracic Cancer - Category: Cancer & Oncology Authors: Tags: CASE REPORT Source Type: research
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Source: Mutation Research Fundamental and Molecular Mechanisms of Mutagenesis - Category: Cytology Source Type: research
Quinolinate (Quin) is a classic example of a biochemical double-edged sword, acting as both essential metabolite and potent neurotoxin. Quin is an important metabolite in the kynurenine pathway of tryptophan catabolism leading to the de novo synthesis of nicotinamide adenine dinucleotide (NAD+). As a precursor for NAD+, Quin can direct a portion of tryptophan catabolism toward replenishing cellular NAD+ levels in response to inflammation and infection. Intracellular Quin levels increase dramatically in response to immune stimulation [e.g., lipopolysaccharide (LPS) or pokeweed mitogen (PWM)] in macrophages, microglia, dendr...
Source: Frontiers in Immunology - Category: Allergy & Immunology Source Type: research
Immune checkpoint blockade (ICB) therapies that target programmed cell death 1 (PD1) and PD1 ligand 1 (PDL1) have demonstrated promising benefits in lung adenocarcinoma (LUAD), and tumor mutational burden (TMB) is the most robust biomarker associated with the efficacy of PD-1-PD-L1 axis blockade in LUAD, but the assessment of TMB by whole-exome sequencing (WES) is rather expensive and time-consuming. Although targeted panel sequencing has been developed and approved by the US Food and Drug Administration (FDA) to estimate TMB, we found that its predictive accuracy for ICB response was significantly lower than WES in LUAD. ...
Source: Frontiers in Oncology - Category: Cancer & Oncology Source Type: research
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Source: Meta Gene - Category: Genetics & Stem Cells Source Type: research
Conclusions: Pediatric CRC presented advanced disease and poor prognosis. These tumors had distinct histologic and molecular presentations, resembling features from different carcinogenic pathways, thus suggesting a heterogenous nature.
Source: Journal of Pediatric Hematology Oncology - Category: Hematology Tags: Original Articles Source Type: research
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