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Mismatch repair

Pingping Jia, Weihang Chai
Genome instability gives rise to cancer. MLH1, commonly known for its important role in mismatch repair (MMR), DNA damage signaling and double-strand break (DSB) repair, safeguards genome stability. Recently we have reported a novel role of MLH1 in preventing aberrant formation of interstitial telomeric sequences (ITSs) at intra-chromosomal regions. Deficiency in MLH1, in particular its N-terminus, leads to an increase of ITSs. Here, we identify that the ATPase activity in the MLH1 N-terminal domain is important for suppressing the formation of ITSs...
March 7, 2018: DNA Repair
Benjamin L Solomon, Ignacio Garrido-Laguna
The advent of immune checkpoint inhibitors (PD-1, PD-L1 and CTLA-4) has resulted in unprecedented long-term remissions of unresectable cancers. The efficacy of checkpoint inhibitors was recently demonstrated in gastrointestinal malignancies with mismatch repair deficiencies (dMMR). Pembrolizumab became the first tissue-agnostic US FDA-approved drug based on the presence of the predictive biomarker dMMR. In addition, the FDA in 2017 approved pembrolizumab for PD-L1-positive advanced gastric cancer in third-line and second-line hepatocellular therapy...
March 15, 2018: Future Oncology
Margareta Heby, Sebastian Lundgren, Björn Nodin, Jacob Elebro, Jakob Eberhard, Karin Jirström
BACKGROUND: Periampullary adenocarcinomas, including pancreatic cancer, are a heterogeneous group of tumors with poor prognosis, where classification into intestinal type (I-type) or pancreatobiliary type (PB-type) is a relevant prognostic factor. The clinical significance of deficient mismatch repair (dMMR) in periampullary adenocarcinoma is comparatively unexplored. Herein, we examined the associations of MMR immunophenotype with long-term survival in patients with resected periampullary adenocarcinoma, with particular reference to morphology and adjuvant treatment response...
March 14, 2018: Journal of Translational Medicine
Takahiro Nakagomi, Taichiro Goto, Yosuke Hirotsu, Daichi Shikata, Yujiro Yokoyama, Rumi Higuchi, Kenji Amemiya, Kenichiro Okimoto, Toshio Oyama, Hitoshi Mochizuki, Masao Omata
Objectives: Pulmonary sarcomatoid carcinomas are rare and generally aggressive tumors composed of carcinomatous and sarcomatous components; however, the evolution of sarcomatoid cancer has not been elucidated. Here, we aimed to evaluate the mutational profiles and phylogeny of sarcomatoid carcinomas using next generation sequencing and in-silico analysis to facilitate the development of novel therapies. Methods: Four patients who underwent surgery for sarcomatoid cancer were enrolled...
February 13, 2018: Oncotarget
Emily C Sheppard, Rikke Brandstrup Morrish, Michael J Dillon, Rebecca Leyland, Richard Chahwan
Epigenetic modifications, such as histone modifications, DNA methylation status, and non-coding RNAs (ncRNA), all contribute to antibody maturation during somatic hypermutation (SHM) and class-switch recombination (CSR). Histone modifications alter the chromatin landscape and, together with DNA primary and tertiary structures, they help recruit Activation-Induced Cytidine Deaminase (AID) to the immunoglobulin (Ig) locus. AID is a potent DNA mutator, which catalyzes cytosine-to-uracil deamination on single-stranded DNA to create U:G mismatches...
2018: Frontiers in Immunology
Peter van Balen, Boris van der Zouwen, Alwine B Kruisselbrink, Matthijs Eefting, Karoly Szuhai, Ekaterina S Jordanova, J H F Falkenburg, Inge Jedema
Introduction: Conditioning regimens preceding allogeneic stem cell transplantation (alloSCT) can cause tissue damage and acceleration of the development of graft-versus-host disease (GVHD). T-cell-depleted alloSCT with postponed donor lymphocyte infusion (DLI) may reduce GVHD, because tissue injury can be restored at the time of DLI. In this study, we investigated the presence of tissue injury and inflammation in skin during the period of hematologic recovery and immune reconstitution after alloSCT...
2018: Frontiers in Immunology
Marina A Pereira, Marcus F K P Ramos, Sheila F Faraj, Andre R Dias, Osmar K Yagi, Bruno Zilberstein, Ivan Cecconello, Venancio A F Alves, Evandro S de Mello, Ulysses Ribeiro
BACKGROUND AND OBJECTIVES: Gastric cancer (GC) has recently been categorized in molecular subtypes, which include Epstein-Barr (EBV)-positive and microsatellite instability (MSI) tumors. This distinction may provide prognostic information and identifies therapeutic targets. The aim of this study was to evaluate EBV, MSI, and PD-L1 immunoexpression in GC and its relationship with clinicopathological characteristics and patient's prognosis. METHODS: We evaluated 287 GC patients who underwent D2-gastrectomy through immunohistochemistry for DNA mismatch repair proteins and PD-L1, and in situ hybridization for EBV detection utilizing tissue microarray...
March 13, 2018: Journal of Surgical Oncology
Xia Cao, Hetong Wang, Defeng Zhuang, He Zhu, Yanli Du, Zhibo Cheng, Weina Cui, Hilary J Rogers, Qianru Zhang, Chunjun Jia, Yuesuo Yang, Peidong Tai, Futi Xie, Wan Liu
DNA mismatch repair (MMR) proteins have been implicated in sensing and correcting DNA damage, and in governing cell cycle progression in the presence of structurally anomalous nucleotide lesions induced by different stresses in mammalian cells. Here, Arabidopsis seedlings were grown hydroponically on 0.5 × MS media containing cadmium (Cd) at 0-4.0 mg L-1 for 5 d. Flow cytometry results indicated that Cd stress induced a G2/M cell cycle arrest both in MLH1-, MSH2-, MSH6-deficient, and in WT roots, associated with marked changes of G2/M regulatory genes, including ATM, ATR, SOG1, BRCA1, WEE1, CYCD4; 1, MAD2, CDKA;1, CYCB1; 2 and CYCB1; 1...
March 3, 2018: Chemosphere
Christina M Nagle, Tracy A O'Mara, Yen Tan, Daniel D Buchanan, Andreas Obermair, Penny Blomfield, Michael A Quinn, Penelope M Webb, Amanda B Spurdle
OBJECTIVE: The risk of developing endometrial cancer (EC) and/or survival following a diagnosis of EC might differ by tumor DNA mismatch repair (MMR) status. We assessed the association between tumor MMR status (classified as MMR-proficient, somatic MMR-deficient, germline MMR-deficient) and the risk of developing EC and survival following a diagnosis of EC. METHODS: We analyzed data from women who participated in the Australian National Endometrial Cancer Study (ANECS) conducted between 2005 and 2007...
February 23, 2018: Journal of Gynecologic Oncology
Devin C Flaherty, John R Jalas, Myung S Sim, Alexander Stojadinovic, Mladjan Protic, Delphine J Lee, Anton J Bilchik
BACKGROUND: The association between tumor mismatch repair status and obesity in colon cancer is not well understood. The authors of this study hypothesized that mismatch repair deficiency in colon cancer may be associated with a lower Body Mass Index (BMI) and improved patient outcome due to an enhanced tumor immune microenvironment. METHODS: For this study, 70 patients were randomly selected from a prospective trial evaluating nodal ultrastaging for colon cancer...
March 12, 2018: Annals of Surgical Oncology
Mehrdad Zeinalian, Morteza Hashemzadeh-Chaleshtori, Rasoul Salehi, Mohammad Hassan Emami
Microsatellite instability (MSI) is a molecular hallmark for some colorectal cancers (CRCs) in which short tandem repeats are prone to mutations along with DNA sequences. It is due to DNA-mismatch-repair system deficiency because of a germline/somatic mutation in mismatch-repair (MMR) genes. The germline mutations lead to Lynch syndrome (LS) while epigenetic gene silencing results in sporadic CRC tumors. We discuss in our paper the most important clinical aspects of MSI testing in CRCs. We reviewed the most reliable relevant studies and clinical trials according to their high-quality methods, particularly within two recent decades...
2018: Advanced Biomedical Research
Marinus H van IJzendoorn, Marian J Bakermans-Kranenburg
Attachment is transmitted from one generation to the next. Adult attachment has been shown to predict the security or insecurity of children's attachment relationship with their parents. In search for the mechanism of intergenerational transmission of attachment sensitive parenting has been the main focus of research during the past four decades. Meta-analytic work confirmed the role of sensitive parenting, but a large explanatory gap remains to be explained. Parental mentalization has not yet fulfilled its promise as a bridge across the transmission gap...
February 27, 2018: Current Opinion in Psychology
Anasheh Halabi, Kayla T B Fuselier, Ed Grabczyk
DNA repeat expansion underlies dozens of progressive neurodegenerative disorders. While the mechanisms driving repeat expansion are not fully understood, increasing evidence suggests a central role for DNA mismatch repair. The mismatch repair recognition complex MutSβ (MSH2-MSH3) that binds mismatched bases and/or insertion/deletion loops has previously been implicated in GAA•TTC, CAG•CTG and CGG•CCG repeat expansion, suggesting a shared mechanism. MutSβ has been studied in a number of models, but the contribution of subsequent steps mediated by the MutL endonuclease in this pathway is less clear...
February 26, 2018: Nucleic Acids Research
Veronica L Cox, Anas A Saeed Bamashmos, Wai Chin Foo, Shiva Gupta, Sireesha Yedururi, Naveen Garg, Hyunseon Christine Kang
Lynch syndrome is the most common hereditary cancer syndrome, the most common cause of heritable colorectal cancer, and the only known heritable cause of endometrial cancer. Other cancers associated with Lynch syndrome include cancers of the ovary, stomach, urothelial tract, and small bowel, and less frequently, cancers of the brain, biliary tract, pancreas, and prostate. The oncogenic tendency of Lynch syndrome stems from a set of genomic alterations of mismatch repair proteins. Defunct mismatch repair proteins cause unusually high instability of regions of the genome called microsatellites...
March 2018: Radiographics: a Review Publication of the Radiological Society of North America, Inc
Alexander N Yatsenko, Paul J Turek
PURPOSE: To examine current evidence of the known effects of advanced paternal age on sperm genetic and epigenetic changes and associated birth defects and diseases in offspring. METHODS: Review of published PubMed literature. RESULTS: Advanced paternal age (> 40 years) is associated with accumulated damage to sperm DNA and mitotic and meiotic quality control mechanisms (mismatch repair) during spermatogenesis. This in turn causes well-delineated abnormalities in sperm chromosomes, both numerical and structural, and increased sperm DNA fragmentation (3%/year of age) and single gene mutations (relative risk, RR 10)...
March 9, 2018: Journal of Assisted Reproduction and Genetics
Michael Hornsey, David W Wareham
Multidrug-resistant lineages of Acinetobacter baumannii (MDRAB) are important nosocomial pathogens. As tigecycline remains active against most MDRAB we sought to investigate whether tigecycline resistance impacts biological fitness. The effects of treatment-emergent tigecycline resistance were investigated in vitro and in vivo using two pre- (AB210; W6976) and post-therapy (AB211; W7282) clinical pairs, recovered from individual patients, where tigecycline resistance was associated with up-regulated efflux activity...
March 9, 2018: Scientific Reports
Mohamed E Salem, Alberto Puccini, Axel Grothey, Derek Raghavan, Richard M Goldberg, Joanne Xiu, W Michael Korn, Benjamin A Weinberg, Jimmy J Hwang, Anthony F Shields, John L Marshall, Philip A Philip, Heinz-Josef Lenz
The efficacy of immunotherapy varies widely among different gastrointestinal cancers. Response to immune checkpoint inhibitors is shown to correlate with tumor mutation load (TML), mismatch repair deficiency (dMMR) status, and programmed cell death-ligand 1 (PD-L1) expression. Herein, we quantify TML, dMMR, and PD-L1 expression and determine their interrelationship in gastrointestinal cancers. Here, a total of 4125 tumors from 14 different gastrointestinal cancer sites were studied using validated assays. Next-generation sequencing (NGS) was performed on genomic DNA isolated from formalin-fixed paraffin-embedded (FFPE) tumor specimens using the NextSeq platform...
March 9, 2018: Molecular Cancer Research: MCR
Alexander J Brown, Aneesa T Al-Soodani, Miles Saul, Stephanie Her, Juan C Garcia, Dale A Ramsden, Chengtao Her, Steven A Roberts
The mechanistic understanding of how DNA double-strand breaks (DSB) are repaired is rapidly advancing in part due to the advent of inducible site-specific break model systems as well as the employment of next-generation sequencing (NGS) technologies to sequence repair junctions at high depth. Unfortunately, the sheer volume of data produced by these methods makes it difficult to analyze the structure of repair junctions manually or with other general-purpose software. Here, we describe methods to produce amplicon libraries of DSB repair junctions for sequencing, to map the sequencing reads, and then to use a robust, custom python script, Hi-FiBR, to analyze the sequence structure of mapped reads...
2018: Methods in Enzymology
Kang-Yi Su, Liang-In Lin, Steven D Goodman, Rong-Syuan Yen, Cho-Yuan Wu, Wei-Chen Chang, Ya-Chien Yang, Wern-Cherng Cheng, Woei-Horng Fang
Deamination of adenine can occur spontaneously under physiological conditions to generate the highly mutagenic lesion, deoxyinosine (hypoxanthine deoxyribonucleotide, dI). In DNA, dI preferably pairs with cytosine rather than thymine and results in A:T to G:C transition mutations after DNA replication. The deamination of adenine is enhanced by ROS from exposure of DNA to ionizing radiation, UV light, nitrous acid, or heat. In Escherichia coli, dI repair is initiated by endonuclease V (endo V; nfi gene product) nicking but a complete repair mechanism has yet to be elucidated...
February 17, 2018: DNA Repair
Micah J McCauley, Leah Furman, Catherine A Dietrich, Ioulia Rouzina, Megan E Núñez, Mark C Williams
One of the most common DNA lesions is created when reactive oxygen alters guanine. 8-oxo-guanine may bind in the anti-conformation with an opposing cytosine or in the syn-conformation with an opposing adenine paired by transversion, and both conformations may alter DNA stability. Here we use optical tweezers to measure the stability of DNA hairpins containing 8-oxoguanine (8oxoG) lesions, comparing the results to predictive models of base-pair energies in the absence of the lesion. Contrasted with either a canonical guanine-cytosine or adenine-thymine pair, an 8oxoG-cytosine base pair shows significant destabilization of several kBT...
March 7, 2018: Nucleic Acids Research
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