Human mismatch repair protein hMutLα is required to repair short slipped-DNAs of trinucleotide repeats.

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Panigrahi, Gagan B; Slean, Meghan M; Simard, Jodie P; Pearson, Christopher E

2012-12-07

Mismatch repair (MMR) is required for proper maintenance of the genome by protecting against mutations. The mismatch repair system has also been implicated as a driver of certain mutations, including disease-associated trinucleotide repeat instability. We recently revealed a requirement of hMutSβ in the repair of short slip-outs containing a single CTG repeat unit (1). The involvement of other MMR proteins in short trinucleotide repeat slip-out repair is unknown. Here we show that hMutLα is required for the highly efficient in vitro repair of single CTG repeat slip-outs, to the same degree as hMutSβ. HEK293T cell extracts, deficient in hMLH1, are unable to process single-repeat slip-outs, but are functional when complemented with hMutLα. The MMR-deficient hMLH1 mutant, T117M, which has a point mutation proximal to the ATP-binding domain, is defective in slip-out repair, further supporting a requirement for hMLH1 in the processing of short slip-outs and possibly the involvement of hMHL1 ATPase activity. Extracts of hPMS2-deficient HEC-1-A cells, which express hMLH1, hMLH3, and hPMS1, are only functional when complemented with hMutLα, indicating that neither hMutLβ nor hMutLγ is sufficient to repair short slip-outs. The resolution of clustered short slip-outs, which are poorly repaired, was partially dependent upon a functional hMutLα. The joint involvement of hMutSβ and hMutLα suggests that repeat instability may be the result of aberrant outcomes of repair attempts.

Selecting patients with young-onset colorectal cancer for mismatch repair gene analysis

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Walker, M; O'Sullivan, B; Perakath, B

2007-01-01

BACKGROUND: Young patients with colorectal cancer are at increased risk of carrying a germline mutation in mismatch repair (MMR) genes. This study investigated the role of clinical criteria and immunohistochemistry for MMR proteins in selecting young patients for mutation testing. METHODS: A cohort...... of 56 consecutive patients with colorectal cancer aged less than 45 years were stratified into three groups based on clinical criteria: 'Amsterdam criteria', 'high risk' and 'young onset only'. Immunohistochemistry for four MMR proteins was carried out and the rate of compliance with clinical guidelines...

Microsatellite Instability Use in Mismatch Repair Gene Sequence Variant Classification

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Bryony A. Thompson

2015-03-01

Full Text Available Inherited mutations in the DNA mismatch repair genes (MMR can cause MMR deficiency and increased susceptibility to colorectal and endometrial cancer. Microsatellite instability (MSI is the defining molecular signature of MMR deficiency. The clinical classification of identified MMR gene sequence variants has a direct impact on the management of patients and their families. For a significant proportion of cases sequence variants of uncertain clinical significance (also known as unclassified variants are identified, constituting a challenge for genetic counselling and clinical management of families. The effect on protein function of these variants is difficult to interpret. The presence or absence of MSI in tumours can aid in determining the pathogenicity of associated unclassified MMR gene variants. However, there are some considerations that need to be taken into account when using MSI for variant interpretation. The use of MSI and other tumour characteristics in MMR gene sequence variant classification will be explored in this review.

A Database to Support the Interpretation of Human Mismatch Repair Gene Variants

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Ou, Jianghua; Niessen, Renee C.; Vonk, Jan; Westers, Helga; Hofstra, Robert M. W.; Sijmons, Rolf H.

Germline mutations in the mismatch repair (MMR) genes MLH1, MSH2, MSH6, or PMS2 can cause Lynch syndrome. This syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC), is an autosomal dominantly-inherited disorder predominantly characterized by colorectal and endometrial cancer.

DNA Mismatch Repair System: Repercussions in Cellular Homeostasis and Relationship with Aging

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Juan Cristóbal Conde-Pérezprina

2012-01-01

Full Text Available The mechanisms that concern DNA repair have been studied in the last years due to their consequences in cellular homeostasis. The diverse and damaging stimuli that affect DNA integrity, such as changes in the genetic sequence and modifications in gene expression, can disrupt the steady state of the cell and have serious repercussions to pathways that regulate apoptosis, senescence, and cancer. These altered pathways not only modify cellular and organism longevity, but quality of life (“health-span”. The DNA mismatch repair system (MMR is highly conserved between species; its role is paramount in the preservation of DNA integrity, placing it as a necessary focal point in the study of pathways that prolong lifespan, aging, and disease. Here, we review different insights concerning the malfunction or absence of the DNA-MMR and its impact on cellular homeostasis. In particular, we will focus on DNA-MMR mechanisms regulated by known repair proteins MSH2, MSH6, PMS2, and MHL1, among others.

Immunotherapy holds the key to cancer treatment and prevention in constitutional mismatch repair deficiency (CMMRD) syndrome.

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Westdorp, Harm; Kolders, Sigrid; Hoogerbrugge, Nicoline; de Vries, I Jolanda M; Jongmans, Marjolijn C J; Schreibelt, Gerty

2017-09-10

Monoallelic germline mutations in one of the DNA mismatch repair (MMR) genes cause Lynch syndrome, with a high lifetime risks of colorectal and endometrial cancer at adult age. Less well known, is the constitutional mismatch repair deficiency (CMMRD) syndrome caused by biallelic germline mutations in MMR genes. This syndrome is characterized by the development of childhood cancer. Patients with CMMRD are at extremely high risk of developing multiple cancers including hematological, brain and intestinal tumors. Mutations in MMR genes impair DNA repair and therefore most tumors of patients with CMMRD are hypermutated. These mutations lead to changes in the translational reading frame, which consequently result in neoantigen formation. Neoantigens are recognized as foreign by the immune system and can induce specific immune responses. The growing evidence on the clinical efficacy of immunotherapies, such as immune checkpoint inhibitors, offers the prospect for treatment of patients with CMMRD. Combining neoantigen-based vaccination strategies and immune checkpoint inhibitors could be an effective way to conquer CMMRD-related tumors. Neoantigen-based vaccines might also be a preventive treatment option in healthy biallelic MMR mutation carriers. Future studies need to reveal the safety and efficacy of immunotherapies for patients with CMMRD. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Somatic mutations in mismatch repair genes in sporadic gastric carcinomas are not a cause but a consequence of the mutator phenotype

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Pinto, Mafalda; Wub, Ying; Mensink, Rob G. J.; Cirnes, Luis; Seruca, Raquel; Hofstra, Robert M. W.

2008-01-01

In hereditary nonpolyposis colorectal cancer (HNPCC), patients' mismatch repair (MMR) gene mutations cause MMR deficiency, leading to microsatellite instability (MSI-H). MSI-H is also found in a substantial fraction of sporadic gastric carcinomas (SGC), mainly due to MLH1 promoter hypermethylation,

Diagnosis of Constitutional Mismatch Repair-Deficiency Syndrome Based on Microsatellite Instability and Lymphocyte Tolerance to Methylating Agents

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Bodo, Sahra; Colas, Chrystelle; Buhard, Olivier

2015-01-01

BACKGROUND & AIMS: Patients with bi-allelic germline mutations in mismatch repair (MMR) genes (MLH1, MSH2, MSH6, or PMS2) develop a rare but severe variant of Lynch syndrome called constitutional MMR deficiency (CMMRD). This syndrome is characterized by early-onset colorectal cancers, lymphomas...... or leukemias, and brain tumors. There is no satisfactory method for diagnosis of CMMRD because screens for mutations in MMR genes are noninformative for 30% of patients. MMR-deficient cancer cells are resistant to genotoxic agents and have microsatellite instability (MSI), due to accumulation of errors...

Znaczenie mechanizmu naprawy DNA błędnie sparowanych zasad azotowych (MMR w raku piersi

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Hanna Romanowicz

2010-04-01

Full Text Available Background: Microsatellite instability (MSI is due to defective DNA mismatch repair. Defects in DNA mismatch-repair (MMR genes lead to replication errors revealed as instability in microsatellite markers. Studieshave shown that breast cancer may be associated with mutations in mismatch repair genes, such as MSH2,MSH3, MSH4, MSH6, MLH1, MLH3, PMS1 and MUTYH. Aim: Results from studies that assayed MMR in sporadic breast cancer are reviewed. Conclusion: Several data suggest that microsatellite instability seems to be a risk factor for breast cancerin subjects belonging to HNPCC (hereditary non-polyposis colorectal cancer families with high incidence of thiscancer and sporadic breast cancer.

Human DNA polymerase delta double-mutant D316A;E318A interferes with DNA mismatch repair in vitro

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Liu, Dekang; Frederiksen, Jane H.; Liberti, Sascha Emilie

2017-01-01

DNA mismatch repair (MMR) is a highly-conserved DNA repair mechanism, whose primary role is to remove DNA replication errors preventing them from manifesting as mutations, thereby increasing the overall genome stability. Defects in MMR are associated with increased cancer risk in humans and other...... organisms. Here, we characterize the interaction between MMR and a proofreading-deficient allele of the human replicative DNA polymerase delta, PolδD316A;E318A, which has a higher capacity for strand displacement DNA synthesis than wild type Polδ. Human cell lines overexpressing PolδD316A;E318A display...

Mismatch repair deficiency does not enhance ENU mutagenesis in the zebrafish germ line.

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Feitsma, H.; de Bruijn, E.; van de Belt, J.; Nijman, I.J.; Cuppen, E.

2008-01-01

S(N)1-type alkylating agents such as N-ethyl-N-nitrosourea (ENU) are very potent mutagens. They act by transferring their alkyl group to DNA bases, which, upon mispairing during replication, can cause single base pair mutations in the next replication cycle. As DNA mismatch repair (MMR) proteins are

Influence of oxidized purine processing on strand directionality of mismatch repair.

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Repmann, Simone; Olivera-Harris, Maite; Jiricny, Josef

2015-04-17

Replicative DNA polymerases are high fidelity enzymes that misincorporate nucleotides into nascent DNA with a frequency lower than [1/10(5)], and this precision is improved to about [1/10(7)] by their proofreading activity. Because this fidelity is insufficient to replicate most genomes without error, nature evolved postreplicative mismatch repair (MMR), which improves the fidelity of DNA replication by up to 3 orders of magnitude through correcting biosynthetic errors that escaped proofreading. MMR must be able to recognize non-Watson-Crick base pairs and excise the misincorporated nucleotides from the nascent DNA strand, which carries by definition the erroneous genetic information. In eukaryotes, MMR is believed to be directed to the nascent strand by preexisting discontinuities such as gaps between Okazaki fragments in the lagging strand or breaks in the leading strand generated by the mismatch-activated endonuclease of the MutL homologs PMS1 in yeast and PMS2 in vertebrates. We recently demonstrated that the eukaryotic MMR machinery can make use also of strand breaks arising during excision of uracils or ribonucleotides from DNA. We now show that intermediates of MutY homolog-dependent excision of adenines mispaired with 8-oxoguanine (G(O)) also act as MMR initiation sites in extracts of human cells or Xenopus laevis eggs. Unexpectedly, G(O)/C pairs were not processed in these extracts and failed to affect MMR directionality, but extracts supplemented with exogenous 8-oxoguanine DNA glycosylase (OGG1) did so. Because OGG1-mediated excision of G(O) might misdirect MMR to the template strand, our findings suggest that OGG1 activity might be inhibited during MMR. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Determining the functional significance of mismatch repair gene missense variants using biochemical and cellular assays

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Heinen, Christopher D; Juel Rasmussen, Lene

2012-01-01

ABSTRACT: With the discovery that the hereditary cancer susceptibility disease Lynch syndrome (LS) is caused by deleterious germline mutations in the DNA mismatch repair (MMR) genes nearly 20 years ago, genetic testing can now be used to diagnose this disorder in patients. A definitive diagnosis...

Physical and functional interactions between Werner syndrome helicase and mismatch-repair initiation factors

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Saydam, Nurten; Kanagaraj, Radhakrishnan; Dietschy, Tobias

2007-01-01

is poorly understood. Here we show that WRN physically interacts with the MSH2/MSH6 (MutSalpha), MSH2/MSH3 (MutSbeta) and MLH1/PMS2 (MutLalpha) heterodimers that are involved in the initiation of mismatch repair (MMR) and the rejection of homeologous recombination. MutSalpha and MutSbeta can strongly...

Integrated analysis of mismatch repair system in malignant astrocytomas.

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Irene Rodríguez-Hernández

Full Text Available Malignant astrocytomas are the most aggressive primary brain tumors with a poor prognosis despite optimal treatment. Dysfunction of mismatch repair (MMR system accelerates the accumulation of mutations throughout the genome causing uncontrolled cell growth. The aim of this study was to characterize the MMR system defects that could be involved in malignant astrocytoma pathogenesis. We analyzed protein expression and promoter methylation of MLH1, MSH2 and MSH6 as well as microsatellite instability (MSI and MMR gene mutations in a set of 96 low- and high-grade astrocytomas. Forty-one astrocytomas failed to express at least one MMR protein. Loss of MSH2 expression was more frequent in low-grade astrocytomas. Loss of MLH1 expression was associated with MLH1 promoter hypermethylation and MLH1-93G>A promoter polymorphism. However, MSI was not related with MMR protein expression and only 5% of tumors were MSI-High. Furthermore, the incidence of tumors carrying germline mutations in MMR genes was low and only one glioblastoma was associated with Lynch syndrome. Interestingly, survival analysis identified that tumors lacking MSH6 expression presented longer overall survival in high-grade astrocytoma patients treated only with radiotherapy while MSH6 expression did not modify the prognosis of those patients treated with both radiotherapy and chemotherapy. Our findings suggest that MMR system alterations are a frequent event in malignant astrocytomas and might help to define a subgroup of patients with different outcome.

Mismatch repair and treatment resistance in ovarian cancer

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Helleman, Jozien; Staveren, Iris L van; Dinjens, Winand NM; Kuijk, Patricia F van; Ritstier, Kirsten; Ewing, Patricia C; Burg, Maria EL van der; Stoter, Gerrit; Berns, Els MJJ

2006-01-01

The treatment of ovarian cancer is hindered by intrinsic or acquired resistance to platinum-based chemotherapy. The aim of this study is to determine the frequency of mismatch repair (MMR) inactivation in ovarian cancer and its association with resistance to platinum-based chemotherapy. We determined, microsatellite instability (MSI) as a marker for MMR inactivation (analysis of BAT25 and BAT26), MLH1 promoter methylation status (methylation specific PCR on bisulfite treated DNA) and mRNA expression of MLH1, MSH2, MSH3, MSH6 and PMS2 (quantitative RT-PCR) in 75 ovarian carcinomas and eight ovarian cancer cell lines MSI was detected in three of the eight cell lines i.e. A2780 (no MLH1 mRNA expression due to promoter methylation), SKOV3 (no MLH1 mRNA expression) and 2774 (no altered expression of MMR genes). Overall, there was no association between cisplatin response and MMR status in these eight cell lines. Seven of the 75 ovarian carcinomas showed MLH1 promoter methylation, however, none of these showed MSI. Forty-six of these patients received platinum-based chemotherapy (11 non-responders, 34 responders, one unknown response). The resistance seen in the eleven non-responders was not related to MSI and therefore also not to MMR inactivation. No MMR inactivation was detected in 75 ovarian carcinoma specimens and no association was seen between MMR inactivation and resistance in the ovarian cancer cell lines as well as the ovarian carcinomas. In the discussion, the results were compared to that of twenty similar studies in the literature including in total 1315 ovarian cancer patients. Although no association between response and MMR status was seen in the primary tumor the possible role of MMR inactivation in acquired resistance deserves further investigation

Mismatch repair and treatment resistance in ovarian cancer

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Helleman, Jozien; Staveren, Iris L van [Department of Medical Oncology, Erasmus MC/Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Dinjens, Winand NM [Department of Pathology, Erasmus MC/Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Kuijk, Patricia F van; Ritstier, Kirsten [Department of Medical Oncology, Erasmus MC/Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Ewing, Patricia C [Department of Pathology, Erasmus MC/Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Burg, Maria EL van der; Stoter, Gerrit [Department of Medical Oncology, Erasmus MC/Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Berns, Els MJJ [Department of Medical Oncology, Erasmus MC/Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Erasmus MC, Department of Medical Oncology, Josephine Nefkens Institute, Room Be424, P.O. Box 1738, 3000 DR (Netherlands)

2006-07-31

The treatment of ovarian cancer is hindered by intrinsic or acquired resistance to platinum-based chemotherapy. The aim of this study is to determine the frequency of mismatch repair (MMR) inactivation in ovarian cancer and its association with resistance to platinum-based chemotherapy. We determined, microsatellite instability (MSI) as a marker for MMR inactivation (analysis of BAT25 and BAT26), MLH1 promoter methylation status (methylation specific PCR on bisulfite treated DNA) and mRNA expression of MLH1, MSH2, MSH3, MSH6 and PMS2 (quantitative RT-PCR) in 75 ovarian carcinomas and eight ovarian cancer cell lines MSI was detected in three of the eight cell lines i.e. A2780 (no MLH1 mRNA expression due to promoter methylation), SKOV3 (no MLH1 mRNA expression) and 2774 (no altered expression of MMR genes). Overall, there was no association between cisplatin response and MMR status in these eight cell lines. Seven of the 75 ovarian carcinomas showed MLH1 promoter methylation, however, none of these showed MSI. Forty-six of these patients received platinum-based chemotherapy (11 non-responders, 34 responders, one unknown response). The resistance seen in the eleven non-responders was not related to MSI and therefore also not to MMR inactivation. No MMR inactivation was detected in 75 ovarian carcinoma specimens and no association was seen between MMR inactivation and resistance in the ovarian cancer cell lines as well as the ovarian carcinomas. In the discussion, the results were compared to that of twenty similar studies in the literature including in total 1315 ovarian cancer patients. Although no association between response and MMR status was seen in the primary tumor the possible role of MMR inactivation in acquired resistance deserves further investigation.

Mismatch repair and treatment resistance in ovarian cancer

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van der Burg Maria EL

2006-07-01

Full Text Available Abstract Background The treatment of ovarian cancer is hindered by intrinsic or acquired resistance to platinum-based chemotherapy. The aim of this study is to determine the frequency of mismatch repair (MMR inactivation in ovarian cancer and its association with resistance to platinum-based chemotherapy. Methods We determined, microsatellite instability (MSI as a marker for MMR inactivation (analysis of BAT25 and BAT26, MLH1 promoter methylation status (methylation specific PCR on bisulfite treated DNA and mRNA expression of MLH1, MSH2, MSH3, MSH6 and PMS2 (quantitative RT-PCR in 75 ovarian carcinomas and eight ovarian cancer cell lines Results MSI was detected in three of the eight cell lines i.e. A2780 (no MLH1 mRNA expression due to promoter methylation, SKOV3 (no MLH1 mRNA expression and 2774 (no altered expression of MMR genes. Overall, there was no association between cisplatin response and MMR status in these eight cell lines. Seven of the 75 ovarian carcinomas showed MLH1 promoter methylation, however, none of these showed MSI. Forty-six of these patients received platinum-based chemotherapy (11 non-responders, 34 responders, one unknown response. The resistance seen in the eleven non-responders was not related to MSI and therefore also not to MMR inactivation. Conclusion No MMR inactivation was detected in 75 ovarian carcinoma specimens and no association was seen between MMR inactivation and resistance in the ovarian cancer cell lines as well as the ovarian carcinomas. In the discussion, the results were compared to that of twenty similar studies in the literature including in total 1315 ovarian cancer patients. Although no association between response and MMR status was seen in the primary tumor the possible role of MMR inactivation in acquired resistance deserves further investigation.

Microsatellites in the Eukaryotic DNA Mismatch Repair Genes as Modulators of Evolutionary Mutation Rate

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Chang, Dong Kyung; Metzgar, David; Wills, Christopher; Boland, C. Richard

2003-01-01

All "minor" components of the human DNA mismatch repair (MMR) system-MSH3, MSH6, PMS2, and the recently discovered MLH3-contain mononucleotide microsatellites in their coding sequences. This intriguing finding contrasts with the situation found in the major components of the DNA MMR system-MSH2 and MLH1-and, in fact, most human genes. Although eukaryotic genomes are rich in microsatellites, non-triplet microsatellites are rare in coding regions. The recurring presence of exonal mononucleotide repeat sequences within a single family of human genes would therefore be considered exceptional.

Inactivation of DNA mismatch repair by variants of uncertain significance in the PMS2 gene.

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Drost, Mark; Koppejan, Hester; de Wind, Niels

2013-11-01

Lynch syndrome (LS) is a common cancer predisposition caused by an inactivating mutation in one of four DNA mismatch repair (MMR) genes. Frequently a variant of uncertain significance (VUS), rather than an obviously pathogenic mutation, is identified in one of these genes. The inability to define pathogenicity of such variants precludes targeted healthcare. Here, we have modified a cell-free assay to test VUS in the MMR gene PMS2 for functional activity. We have analyzed nearly all VUS in PMS2 found thus far and describe loss of MMR activity for five, suggesting the applicability of the assay for diagnosis of LS. © 2013 WILEY PERIODICALS, INC.

Interdependence of DNA mismatch repair proteins MLH1 and MSH2 in apoptosis in human colorectal carcinoma cell lines.

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Hassen, Samar; Ali, Akhtar A; Kilaparty, Surya P; Al-Anbaky, Qudes A; Majeed, Waqar; Boman, Bruce M; Fields, Jeremy Z; Ali, Nawab

2016-01-01

The mammalian DNA mismatch repair (MMR) system consists of a number of proteins that play important roles in repair of base pair mismatch mutations and in maintenance of genomic integrity. A defect in this system can cause genetic instability, which can lead to carcinogenesis. For instance, a germline mutation in one of the mismatch repair proteins, especially MLH1 or MSH2, is responsible for hereditary non-polyposis colorectal cancer. These MMR proteins also play an important role in the induction of apoptosis. Accordingly, altered expression of or a defect in MLH1 or MSH2 may confer resistance to anti-cancer drugs used in chemotherapy. We hypothesized that the ability of these two MMR proteins to regulate apoptosis are interdependent. Moreover, a defect in either one may confer resistance to chemotherapy by an inability to trigger apoptosis. To this end, we studied three cell lines-SW480, LoVo, and HTC116. These cell lines were selected based on their differential expression of MLH1 and MSH2 proteins. SW480 expresses both MLH1 and MSH2; LoVo expresses only MLH1 but not MSH2; HCT116 expresses only MSH2 but not MLH1 protein. MTT assays, a measure of cytotoxicity, showed that there were different cytotoxic effects of an anti-cancer drug, etoposide, on these cell lines, effects that were correlated with the MMR status of the cells. Cells that are deficient in MLH1 protein (HCT116 cells) were resistant to the drug. Cells that express both MLH1 and MSH2 proteins (SW480 cells) showed caspase-3 cleavage, an indicator of apoptosis. Cells that lack MLH1 (HCT116 cells) did not show any caspase-3 cleavage. Expression of full-length MLH1 protein was decreased in MMR proficient (SW480) cells during apoptosis; it remained unchanged in cells that lack MSH2 (LoVo cells). The expression of MSH2 protein remained unchanged during apoptosis both in MMR proficient (SW480) and deficient (HCT116) cells. Studies on translocation of MLH1 protein from nucleus to cytosolic fraction, an

Involvement of the DNA mismatch repair system in cisplatin sensitivity of testicular germ cell tumours

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Rudolph, Christiane; Melau, Cecilie; Nielsen, John E.

2017-01-01

in the majority of tumours, although the underlying mechanism largely remains to be elucidated. The aim of this study was to investigate the role of the DNA mismatch repair (MMR) system in the cisplatin sensitivity of TGCT. MethodsThe expression pattern of key MMR proteins, including MSH2, MSH6, MLH1 and PMS2...... proteins, in particular MSH2 and MLH1, which are involved in the recognition of cisplatin adducts and in activation of the DNA damage response pathway to initiate apoptosis....

Pitfalls in molecular analysis for mismatch repair deficiency in a family with biallelic pms2 germline mutations.

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Leenen, C H M; Geurts-Giele, W R R; Dubbink, H J; Reddingius, R; van den Ouweland, A M; Tops, C M J; van de Klift, H M; Kuipers, E J; van Leerdam, M E; Dinjens, W N M; Wagner, A

2011-12-01

Heterozygous germline mutations in the mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2 cause Lynch syndrome. Biallelic mutations in the MMR genes are associated with a childhood cancer syndrome [constitutional mismatch repair deficiency (CMMR-D)]. This is predominantly characterized by hematological malignancies and tumors of the bowel and brain, often associated with signs of neurofibromatosis type 1 (NF1). Diagnostic strategies for selection of patients for MMR gene analysis include analysis of microsatellite instability (MSI) and immunohistochemical (IHC) analysis of MMR proteins in tumor tissue. We report the clinical characterization and molecular analyses of tumor specimens from a family with biallelic PMS2 germline mutations. This illustrates the pitfalls of present molecular screening strategies. Tumor tissues of five family members were analyzed for MSI and IHC. MSI was observed in only one of the analyzed tissues. However, IHC analysis of brain tumor tissue of the index patient and his sister showed absence of PMS2 expression, and germline mutation analyses showed biallelic mutations in PMS2: p.Ser46IIe and p.Pro246fs. The same heterozygous mutations were confirmed in the father and mother, respectively. These data support the conclusion that in case of a clinical phenotype of CMMR-D, it is advisable to routinely combine MSI analysis with IHC analysis for the expression of MMR proteins. With inconclusive or conflicting results, germline mutation analysis of the MMR genes should be considered after thorough counselling of the patients and/or their relatives. © 2011 John Wiley & Sons A/S.

Constitutional mismatch repair-deficiency syndrome: have we so far seen only the tip of an iceberg?

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Wimmer, Katharina; Etzler, Julia

2008-09-01

Heterozygous mutations in one of the mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2 cause the dominant adult cancer syndrome termed Lynch syndrome or hereditary non-polyposis colorectal cancer. During the past 10 years, some 35 reports have delineated the phenotype of patients with biallelic inheritance of mutations in one of these MMR genes. The patients suffer from a condition that is characterised by the development of childhood cancers, mainly haematological malignancies and/or brain tumours, as well as early-onset colorectal cancers. Almost all patients also show signs reminiscent of neurofibromatosis type 1, mainly café au lait spots. Alluding to the underlying mechanism, this condition may be termed as "constitutional mismatch repair-deficiency (CMMR-D) syndrome". To give an overview of the current knowledge and its implications of this recessively inherited cancer syndrome we summarise here the genetic, clinical and pathological findings of the so far 78 reported patients of 46 families suffering from this syndrome.

Alkylation damage causes MMR-dependent chromosomal instability in vertebrate embryos.

NARCIS (Netherlands)

Feitsma, H.; Akay, A.; Cuppen, E.

2008-01-01

S(N)1-type alkylating agents, like N-methyl-N-nitrosourea (MNU) and N-ethyl-N-nitrosourea (ENU), are potent mutagens. Exposure to alkylating agents gives rise to O(6)-alkylguanine, a modified base that is recognized by DNA mismatch repair (MMR) proteins but is not repairable, resulting in

Frameshift mutational target gene analysis identifies similarities and differences in constitutional mismatch repair-deficiency and Lynch syndrome.

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Maletzki, Claudia; Huehns, Maja; Bauer, Ingrid; Ripperger, Tim; Mork, Maureen M; Vilar, Eduardo; Klöcking, Sabine; Zettl, Heike; Prall, Friedrich; Linnebacher, Michael

2017-07-01

Mismatch-repair deficient (MMR-D) malignancies include Lynch Syndrome (LS), which is secondary to germline mutations in one of the MMR genes, and the rare childhood-form of constitutional mismatch repair-deficiency (CMMR-D); caused by bi-allelic MMR gene mutations. A hallmark of LS-associated cancers is microsatellite instability (MSI), characterized by coding frameshift mutations (cFSM) in target genes. By contrast, tumors arising in CMMR-D patients are thought to display a somatic mutation pattern differing from LS. This study has the main goal to identify cFSM in MSI target genes relevant in CMMR-D and to compare the spectrum of common somatic mutations, including alterations in DNA polymerases POLE and D1 between LS and CMMR-D. CMMR-D-associated tumors harbored more somatic mutations compared to LS cases, especially in the TP53 gene and in POLE and POLD1, where novel mutations were additionally identified. Strikingly, MSI in classical mononucleotide markers BAT40 and CAT25 was frequent in CMMR-D cases. MSI-target gene analysis revealed mutations in CMMR-D-associated tumors, some of them known to be frequently hit in LS, such as RNaseT2, HT001, and TGFβR2. Our results imply a general role for these cFSM as potential new drivers of MMR-D tumorigenesis. © 2017 Wiley Periodicals, Inc.

Mismatch repair deficiency: a temozolomide resistance factor in medulloblastoma cell lines that is uncommon in primary medulloblastoma tumours

NARCIS (Netherlands)

von Bueren, A. O.; Bacolod, M. D.; Hagel, C.; Heinimann, K.; Fedier, A.; Kordes, U.; Pietsch, T.; Koster, J.; Grotzer, M. A.; Friedman, H. S.; Marra, G.; Kool, M.; Rutkowski, S.

2012-01-01

BACKGROUND: Tumours are responsive to temozolomide (TMZ) if they are deficient in O-6-methylguanine-DNA methyltransferase (MGMT), and mismatch repair (MMR) proficient. METHODS: The effect of TMZ on medulloblastoma (MB) cell killing was analysed with clonogenic survival assays. Expression of DNA

The unstructured linker arms of Mlh1-Pms1 are important for interactions with DNA during mismatch repair

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Plys, Aaron J.; Rogacheva, Maria V.; Greene, Eric C.; Alani, Eric

2012-01-01

DNA mismatch repair (MMR) models have proposed that MSH proteins identify DNA polymerase errors while interacting with the DNA replication fork. MLH proteins (primarily Mlh1-Pms1 in baker’s yeast) then survey the genome for lesion-bound MSH proteins. The resulting MSH-MLH complex formed at a DNA lesion initiates downstream steps in repair. MLH proteins act as dimers and contain long (20 – 30 nanometers) unstructured arms that connect two terminal globular domains. These arms can vary between 100 to 300 amino acids in length, are highly divergent between organisms, and are resistant to amino acid substitutions. To test the roles of the linker arms in MMR, we engineered a protease cleavage site into the Mlh1 linker arm domain of baker’s yeast Mlh1-Pms1. Cleavage of the Mlh1 linker arm in vitro resulted in a defect in Mlh1-Pms1 DNA binding activity, and in vivo proteolytic cleavage resulted in a complete defect in MMR. We then generated a series of truncation mutants bearing Mlh1 and Pms1 linker arms of varying lengths. This work revealed that MMR is greatly compromised when portions of the Mlh1 linker are removed, whereas repair is less sensitive to truncation of the Pms1 linker arm. Purified complexes containing truncations in Mlh1 and Pms1 linker arms were analyzed and found to have differential defects in DNA binding that also correlated with the ability to form a ternary complex with Msh2-Msh6 and mismatch DNA. These observations are consistent with the unstructured linker domains of MLH proteins providing distinct interactions with DNA during MMR. PMID:22659005

Mismatch repair deficiency commonly precedes adenoma formation in Lynch Syndrome-Associated colorectal tumorigenesis.

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Sekine, Shigeki; Mori, Taisuke; Ogawa, Reiko; Tanaka, Masahiro; Yoshida, Hiroshi; Taniguchi, Hirokazu; Nakajima, Takeshi; Sugano, Kokichi; Yoshida, Teruhiko; Kato, Mamoru; Furukawa, Eisaku; Ochiai, Atsushi; Hiraoka, Nobuyoshi

2017-08-01

Lynch syndrome is a cancer predisposition syndrome caused by germline mutations in mismatch repair (MMR) genes. MMR deficiency is a ubiquitous feature of Lynch syndrome-associated colorectal adenocarcinomas; however, it remains unclear when the MMR-deficient phenotype is acquired during tumorigenesis. To probe this issue, the present study examined genetic alterations and MMR statuses in Lynch syndrome-associated colorectal adenomas and adenocarcinomas, in comparison with sporadic adenomas. Among the Lynch syndrome-associated colorectal tumors, 68 of 86 adenomas (79%) and all adenocarcinomas were MMR-deficient, whereas all the sporadic adenomas were MMR-proficient, as determined by microsatellite instability testing and immunohistochemistry for MMR proteins. Sequencing analyses identified APC or CTNNB1 mutations in the majority of sporadic adenomas (58/84, 69%) and MMR-proficient Lynch syndrome-associated adenomas (13/18, 72%). However, MMR-deficient Lynch syndrome-associated adenomas had less APC or CTNNB1 mutations (25/68, 37%) and frequent frameshift RNF43 mutations involving mononucleotide repeats (45/68, 66%). Furthermore, frameshift mutations affecting repeat sequences constituted 14 of 26 APC mutations (54%) in MMR-deficient adenomas whereas these frameshift mutations were rare in MMR-proficient adenomas in patients with Lynch syndrome (1/12, 8%) and in sporadic adenomas (3/52, 6%). Lynch syndrome-associated adenocarcinomas exhibited mutation profiles similar to those of MMR-deficient adenomas. Considering that WNT pathway activation sufficiently drives colorectal adenoma formation, the distinct mutation profiles of WNT pathway genes in Lynch syndrome-associated adenomas suggest that MMR deficiency commonly precedes adenoma formation.

Structural, molecular and cellular functions of MSH2 and MSH6 during DNA mismatch repair, damage signaling and other noncanonical activities

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Edelbrock, Michael A., E-mail: Edelbrock@findlay.edu [The University of Findlay, 1000 North Main Street, Findlay, OH 45840 (United States); Kaliyaperumal, Saravanan, E-mail: Saravanan.Kaliyaperumal@hms.harvard.edu [Division of Comparative Medicine and Pathology, New England Primate Research Center, One Pine Hill Drive, Southborough, MA 01772 (United States); Williams, Kandace J., E-mail: Kandace.williams@utoledo.edu [University of Toledo College of Medicine and Life Sciences, Department of Biochemistry and Cancer Biology, 3000 Transverse Dr., Toledo, OH 43614 (United States)

2013-03-15

The field of DNA mismatch repair (MMR) has rapidly expanded after the discovery of the MutHLS repair system in bacteria. By the mid 1990s yeast and human homologues to bacterial MutL and MutS had been identified and their contribution to hereditary non-polyposis colorectal cancer (HNPCC; Lynch syndrome) was under intense investigation. The human MutS homologue 6 protein (hMSH6), was first reported in 1995 as a G:T binding partner (GTBP) of hMSH2, forming the hMutSα mismatch-binding complex. Signal transduction from each DNA-bound hMutSα complex is accomplished by the hMutLα heterodimer (hMLH1 and hPMS2). Molecular mechanisms and cellular regulation of individual MMR proteins are now areas of intensive research. This review will focus on molecular mechanisms associated with mismatch binding, as well as emerging evidence that MutSα, and in particular, MSH6, is a key protein in MMR-dependent DNA damage response and communication with other DNA repair pathways within the cell. MSH6 is unstable in the absence of MSH2, however it is the DNA lesion-binding partner of this heterodimer. MSH6, but not MSH2, has a conserved Phe-X-Glu motif that recognizes and binds several different DNA structural distortions, initiating different cellular responses. hMSH6 also contains the nuclear localization sequences required to shuttle hMutSα into the nucleus. For example, upon binding to O{sup 6}meG:T, MSH6 triggers a DNA damage response that involves altered phosphorylation within the N-terminal disordered domain of this unique protein. While many investigations have focused on MMR as a post-replication DNA repair mechanism, MMR proteins are expressed and active in all phases of the cell cycle. There is much more to be discovered about regulatory cellular roles that require the presence of MutSα and, in particular, MSH6.

Structural, molecular and cellular functions of MSH2 and MSH6 during DNA mismatch repair, damage signaling and other noncanonical activities

International Nuclear Information System (INIS)

Edelbrock, Michael A.; Kaliyaperumal, Saravanan; Williams, Kandace J.

2013-01-01

The field of DNA mismatch repair (MMR) has rapidly expanded after the discovery of the MutHLS repair system in bacteria. By the mid 1990s yeast and human homologues to bacterial MutL and MutS had been identified and their contribution to hereditary non-polyposis colorectal cancer (HNPCC; Lynch syndrome) was under intense investigation. The human MutS homologue 6 protein (hMSH6), was first reported in 1995 as a G:T binding partner (GTBP) of hMSH2, forming the hMutSα mismatch-binding complex. Signal transduction from each DNA-bound hMutSα complex is accomplished by the hMutLα heterodimer (hMLH1 and hPMS2). Molecular mechanisms and cellular regulation of individual MMR proteins are now areas of intensive research. This review will focus on molecular mechanisms associated with mismatch binding, as well as emerging evidence that MutSα, and in particular, MSH6, is a key protein in MMR-dependent DNA damage response and communication with other DNA repair pathways within the cell. MSH6 is unstable in the absence of MSH2, however it is the DNA lesion-binding partner of this heterodimer. MSH6, but not MSH2, has a conserved Phe-X-Glu motif that recognizes and binds several different DNA structural distortions, initiating different cellular responses. hMSH6 also contains the nuclear localization sequences required to shuttle hMutSα into the nucleus. For example, upon binding to O 6 meG:T, MSH6 triggers a DNA damage response that involves altered phosphorylation within the N-terminal disordered domain of this unique protein. While many investigations have focused on MMR as a post-replication DNA repair mechanism, MMR proteins are expressed and active in all phases of the cell cycle. There is much more to be discovered about regulatory cellular roles that require the presence of MutSα and, in particular, MSH6

Completion of meiosis in male zebrafish (Danio rerio) despite lack of DNA mismatch repair gene mlh1

NARCIS (Netherlands)

Leal, M.C.; Feitsma, H.; Cuppen, E.; França, L.R.; Schulz, R.W.

2008-01-01

Mlh1 is a member of DNA mismatch repair (MMR) machinery and is also essential for the stabilization of crossovers during the first meiotic division. Recently, we have shown that zebrafish mlh1 mutant males are completely infertile because of a block in metaphase I, whereas females are fertile

Role of Cell Cycle Regulation and MLH1, A Key DNA Mismatch Repair Protein, In Adaptive Survival Responses. Final Report

Energy Technology Data Exchange (ETDEWEB)

David A. Boothman

1999-08-11

Due to several interesting findings on both adaptive survival responses (ASRs) and DNA mismatch repair (MMR), this grant was separated into two discrete Specific Aim sets (each with their own discrete hypotheses). The described experiments were simultaneously performed.

C-Terminal Fluorescent Labeling Impairs Functionality of DNA Mismatch Repair Proteins

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Brieger, Angela; Plotz, Guido; Hinrichsen, Inga; Passmann, Sandra; Adam, Ronja; Zeuzem, Stefan

2012-01-01

The human DNA mismatch repair (MMR) process is crucial to maintain the integrity of the genome and requires many different proteins which interact perfectly and coordinated. Germline mutations in MMR genes are responsible for the development of the hereditary form of colorectal cancer called Lynch syndrome. Various mutations mainly in two MMR proteins, MLH1 and MSH2, have been identified so far, whereas 55% are detected within MLH1, the essential component of the heterodimer MutLα (MLH1 and PMS2). Most of those MLH1 variants are pathogenic but the relevance of missense mutations often remains unclear. Many different recombinant systems are applied to filter out disease-associated proteins whereby fluorescent tagged proteins are frequently used. However, dye labeling might have deleterious effects on MutLα's functionality. Therefore, we analyzed the consequences of N- and C-terminal fluorescent labeling on expression level, cellular localization and MMR activity of MutLα. Besides significant influence of GFP- or Red-fusion on protein expression we detected incorrect shuttling of single expressed C-terminal GFP-tagged PMS2 into the nucleus and found that C-terminal dye labeling impaired MMR function of MutLα. In contrast, N-terminal tagged MutLαs retained correct functionality and can be recommended both for the analysis of cellular localization and MMR efficiency. PMID:22348133

C-terminal fluorescent labeling impairs functionality of DNA mismatch repair proteins.

Directory of Open Access Journals (Sweden)

Angela Brieger

Full Text Available The human DNA mismatch repair (MMR process is crucial to maintain the integrity of the genome and requires many different proteins which interact perfectly and coordinated. Germline mutations in MMR genes are responsible for the development of the hereditary form of colorectal cancer called Lynch syndrome. Various mutations mainly in two MMR proteins, MLH1 and MSH2, have been identified so far, whereas 55% are detected within MLH1, the essential component of the heterodimer MutLα (MLH1 and PMS2. Most of those MLH1 variants are pathogenic but the relevance of missense mutations often remains unclear. Many different recombinant systems are applied to filter out disease-associated proteins whereby fluorescent tagged proteins are frequently used. However, dye labeling might have deleterious effects on MutLα's functionality. Therefore, we analyzed the consequences of N- and C-terminal fluorescent labeling on expression level, cellular localization and MMR activity of MutLα. Besides significant influence of GFP- or Red-fusion on protein expression we detected incorrect shuttling of single expressed C-terminal GFP-tagged PMS2 into the nucleus and found that C-terminal dye labeling impaired MMR function of MutLα. In contrast, N-terminal tagged MutLαs retained correct functionality and can be recommended both for the analysis of cellular localization and MMR efficiency.

DNA Mismatch Repair Deficiency Promotes Genomic Instability in a Subset of Papillary Thyroid Cancers.

Science.gov (United States)

Javid, Mahsa; Sasanakietkul, Thanyawat; Nicolson, Norman G; Gibson, Courtney E; Callender, Glenda G; Korah, Reju; Carling, Tobias

2018-02-01

Efficient DNA damage repair by MutL-homolog DNA mismatch repair (MMR) enzymes, MLH1, MLH3, PMS1 and PMS2, are required to maintain thyrocyte genomic integrity. We hypothesized that persistent oxidative stress and consequent transcriptional dysregulation observed in thyroid follicles will lead to MMR deficiency and potentiate papillary thyroid tumorigenesis. MMR gene expression was analyzed by targeted microarray in 18 papillary thyroid cancer (PTC), 9 paracarcinoma normal thyroid (PCNT) and 10 normal thyroid (NT) samples. The findings were validated by qRT-PCR, and in follicular thyroid cancers (FTC) and follicular thyroid adenomas (FTA) for comparison. FOXO transcription factor expression was also analyzed. Protein expression was assessed by immunohistochemistry. Genomic integrity was evaluated by whole-exome sequencing-derived read-depth analysis and Mann-Whitney U test. Clinical correlations were assessed using Fisher's exact and t tests. Microarray and qRT-PCR revealed reduced expression of all four MMR genes in PTC compared with PCNT and of PMS2 compared with NT. FTC and FTA showed upregulation in MLH1, MLH3 and PMS2. PMS2 protein expression correlated with the mRNA expression pattern. FOXO1 showed lower expression in PMS2-deficient PTCs (log2-fold change -1.72 vs. -0.55, U = 11, p clinical characteristics. MMR deficiency, potentially promoted by FOXO1 suppression, may explain the etiology for PTC development in some patients. FTC and FTA retain MMR activity and are likely caused by a different tumorigenic pathway.

Completion of meiosis in male zebrafish (Danio rerio) despite lack of DNA mismatch repair gene mlh1.

NARCIS (Netherlands)

Leal, M.C.; Feitsma, H.; Cuppen, E.; Franca, L.R.; Schulz, R.W.

2008-01-01

Mlh1 is a member of DNA mismatch repair (MMR) machinery and is also essential for the stabilization of crossovers during the first meiotic division. Recently, we have shown that zebrafish mlh1 mutant males are completely infertile because of a block in metaphase I, whereas females are fertile but

Low frequency of defective mismatch repair in a population-based series of upper urothelial carcinoma

International Nuclear Information System (INIS)

Ericson, Kajsa M; Isinger, Anna P; Isfoss, Björn L; Nilbert, Mef C

2005-01-01

Upper urothelial cancer (UUC), i.e. transitional cell carcinomas of the renal pelvis and the ureter, occur at an increased frequency in patients with hereditary nonpolyposis colorectal cancer (HNPCC). Defective mismatch repair (MMR) specifically characterizes HNPCC-associated tumors, but also occurs in subsets of some sporadic tumors, e.g. in gastrointestinal cancer and endometrial cancer. We assessed the contribution of defective MMR to the development of UUC in a population-based series from the southern Swedish Cancer Registry, through microsatellite instability (MSI) analysis and immunohistochemical evaluation of expression of the MMR proteins MLH1, PMS2, MSH2, and MSH6. A MSI-high phenotype was identified in 9/216 (4%) successfully analyzed patients and a MSI-low phenotype in 5/216 (2%). Loss of MMR protein immunostaining was found in 11/216 (5%) tumors, and affected most commonly MSH2 and MSH6. This population-based series indicates that somatic MMR inactivation is a minor pathway in the development of UUC, but tumors that display defective MMR are, based on the immunohistochemical expression pattern, likely to be associated with HNPCC

Low frequency of defective mismatch repair in a population-based series of upper urothelial carcinoma

Energy Technology Data Exchange (ETDEWEB)

Ericson, Kajsa M; Isinger, Anna P [Departments of Oncology, University Hospital, Lund (Sweden); Isfoss, Björn L [Departments of Pathology, University Hospital, Lund (Sweden); Nilbert, Mef C [Departments of Oncology, University Hospital, Lund (Sweden)

2005-01-01

Upper urothelial cancer (UUC), i.e. transitional cell carcinomas of the renal pelvis and the ureter, occur at an increased frequency in patients with hereditary nonpolyposis colorectal cancer (HNPCC). Defective mismatch repair (MMR) specifically characterizes HNPCC-associated tumors, but also occurs in subsets of some sporadic tumors, e.g. in gastrointestinal cancer and endometrial cancer. We assessed the contribution of defective MMR to the development of UUC in a population-based series from the southern Swedish Cancer Registry, through microsatellite instability (MSI) analysis and immunohistochemical evaluation of expression of the MMR proteins MLH1, PMS2, MSH2, and MSH6. A MSI-high phenotype was identified in 9/216 (4%) successfully analyzed patients and a MSI-low phenotype in 5/216 (2%). Loss of MMR protein immunostaining was found in 11/216 (5%) tumors, and affected most commonly MSH2 and MSH6. This population-based series indicates that somatic MMR inactivation is a minor pathway in the development of UUC, but tumors that display defective MMR are, based on the immunohistochemical expression pattern, likely to be associated with HNPCC.

DNA Mismatch Binding and Antiproliferative Activity of Rhodium Metalloinsertors

Science.gov (United States)

Ernst, Russell J.; Song, Hang; Barton, Jacqueline K.

2009-01-01

Deficiencies in mismatch repair (MMR) are associated with carcinogenesis. Rhodium metalloinsertors bind to DNA base mismatches with high specificity and inhibit cellular proliferation preferentially in MMR-deficient cells versus MMR-proficient cells. A family of chrysenequinone diimine complexes of rhodium with varying ancillary ligands that serve as DNA metalloinsertors has been synthesized, and both DNA mismatch binding affinities and antiproliferative activities against the human colorectal carcinoma cell lines HCT116N and HCT116O, an isogenic model system for MMR deficiency, have been determined. DNA photocleavage experiments reveal that all complexes bind to the mismatch sites with high specificities; DNA binding affinities to oligonucleotides containing single base CA and CC mismatches, obtained through photocleavage titration or competition, vary from 104 to 108 M−1 for the series of complexes. Significantly, binding affinities are found to be inversely related to ancillary ligand size and directly related to differential inhibition of the HCT116 cell lines. The observed trend in binding affinity is consistent with the metalloinsertion mode where the complex binds from the minor groove with ejection of mismatched base pairs. The correlation between binding affinity and targeting of the MMR-deficient cell line suggests that rhodium metalloinsertors exert their selective biological effects on MMR-deficient cells through mismatch binding in vivo. PMID:19175313

Evaluating Mismatch Repair Deficiency in Pancreatic Adenocarcinoma: Challenges and Recommendations.

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Hu, Zishuo I; Shia, Jinru; Stadler, Zsofia K; Varghese, Anna M; Capanu, Marinela; Salo-Mullen, Erin; Lowery, Maeve A; Diaz, Luis A; Mandelker, Diana; Yu, Kenneth H; Zervoudakis, Alice; Kelsen, David P; Iacobuzio-Donahue, Christine A; Klimstra, David S; Saltz, Leonard B; Sahin, Ibrahim H; O'Reilly, Eileen M

2018-03-15

Purpose: Immune checkpoint inhibition has been shown to generate profound and durable responses in mismatch repair deficient (MMR-D) solid tumors and has elicited interest in detection tools and strategies to guide therapeutic decision-making. Herein we address questions on the appropriate screening, detection methods, patient selection, and initiation of therapy for MMR-D pancreatic ductal adenocarcinoma (PDAC) and assess the utility of next-generation sequencing (NGS) in providing additional prognostic and predictive information for MMR-D PDAC. Experimental Design: Archival and prospectively acquired samples and matched normal DNA from N = 833 PDAC cases were analyzed using a hybridization capture-based, NGS assay designed to perform targeted deep sequencing of all exons and selected introns of 341 to 468 cancer-associated genes. A computational program using NGS data derived the MSI status from the tumor-normal paired genome sequencing data. Available germline testing, IHC, and microsatellite instability (MSI) PCR results were reviewed to assess and confirm MMR-D and MSI status. Results: MMR-D in PDAC is a rare event among PDAC patients (7/833), occurring at a frequency of 0.8%. Loss of MMR protein expression by IHC, high mutational load, and elevated MSIsensor scores were correlated with MMR-D PDAC. All 7 MMR-D PDAC patients in the study were found to have Lynch syndrome. Four (57%) of the MMR-D patients treated with immune checkpoint blockade had treatment benefit (1 complete response, 2 partial responses, 1 stable disease). Conclusions: An integrated approach of germline testing and somatic analyses of tumor tissues in advanced PDAC using NGS may help guide future development of immune and molecularly directed therapies in PDAC patients. Clin Cancer Res; 24(6); 1326-36. ©2018 AACR . ©2018 American Association for Cancer Research.

Role of Cell Cycle Regulation and MLH1, A Key DNA Mismatch Repair Protein, In Adaptive Survival Responses. Final Report; FINAL

International Nuclear Information System (INIS)

David A. Boothman

1999-01-01

Due to several interesting findings on both adaptive survival responses (ASRs) and DNA mismatch repair (MMR), this grant was separated into two discrete Specific Aim sets (each with their own discrete hypotheses). The described experiments were simultaneously performed

DNA mismatch repair deficiency and hereditary syndromes in Latino patients with colorectal cancer.

Science.gov (United States)

Ricker, Charité N; Hanna, Diana L; Peng, Cheng; Nguyen, Nathalie T; Stern, Mariana C; Schmit, Stephanie L; Idos, Greg E; Patel, Ravi; Tsai, Steven; Ramirez, Veronica; Lin, Sonia; Shamasunadara, Vinay; Barzi, Afsaneh; Lenz, Heinz-Josef; Figueiredo, Jane C

2017-10-01

The landscape of hereditary syndromes and clinicopathologic characteristics among US Latino/Hispanic individuals with colorectal cancer (CRC) remains poorly understood. A total of 265 patients with CRC who were enrolled in the Hispanic Colorectal Cancer Study were included in the current study. Information regarding CRC risk factors was elicited through interviews, and treatment and survival data were abstracted from clinical charts. Tumor studies and germline genetic testing results were collected from medical records or performed using standard molecular methods. The mean age of the patients at the time of diagnosis was 53.7 years (standard deviation, 10.3 years), and 48.3% were female. Overall, 21.2% of patients reported a first-degree or second-degree relative with CRC; 3.4% met Amsterdam I/II criteria. With respect to Bethesda guidelines, 38.5% of patients met at least 1 criterion. Of the 161 individuals who had immunohistochemistry and/or microsatellite instability testing performed, 21 (13.0%) had mismatch repair (MMR)-deficient (dMMR) tumors. dMMR tumors were associated with female sex (61.9%), earlier age at the time of diagnosis (50.4 ± 12.4 years), proximal location (61.9%), and first-degree (23.8%) or second-degree (9.5%) family history of CRC. Among individuals with dMMR tumors, 13 (61.9%) had a germline MMR mutation (MutL homolog 1 [MLH1] in 6 patients; MutS homolog 2 [MSH2] in 4 patients; MutS homolog 6 [MHS6] in 2 patients; and PMS1 homolog 2, mismatch repair system component [PMS2] in 1 patient). The authors identified 2 additional MLH1 mutation carriers by genetic testing who had not received immunohistochemistry/microsatellite instability testing. In total, 5.7% of the entire cohort were confirmed to have Lynch syndrome. In addition, 6 individuals (2.3%) had a polyposis phenotype. The percentage of dMMR tumors noted among Latino individuals (13%) is similar to estimates in non-Hispanic white individuals. In the current study, the majority of

The dual nature of mismatch repair as antimutator and mutator: for better or for worse

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Sara Thornby Bak

2014-08-01

Full Text Available DNA is constantly under attack by a number of both exogenous and endogenous agents that challenge its integrity. Among the mechanisms that have evolved to counteract this deleterious action, mismatch repair (MMR has specialized in removing DNA biosynthetic errors that occur when replicating the genome. Malfunction or inactivation of this system results in an increase in spontaneous mutability and a strong predisposition to tumor development. Besides this key corrective role, MMR proteins are involved in other pathways of DNA metabolism such as mitotic and meiotic recombination and processing of oxidative damage. Surprisingly, MMR is also required for certain mutagenic processes. The mutagenic MMR has beneficial consequences contributing to the generation of a vast repertoire of antibodies through class switch recombination and somatic hypermutation processes. However, this non-canonical mutagenic MMR also has detrimental effects; it promotes repeat expansions associated with neuromuscular and neurodegenerative diseases and may contribute to cancer/disease-related aberrant mutations and translocations. The reaction responsible for replication error correction has been the most thoroughly studied and it is the subject to numerous reviews. This review describes briefly the biochemistry of MMR and focuses primarily on the non-canonical MMR activities described in mammals as well as emerging research implicating interplay of MMR and chromatin.

Spectrum of mismatch repair gene mutations and clinical presentation of Hispanic individuals with Lynch syndrome.

Science.gov (United States)

Sunga, Annette Y; Ricker, Charité; Espenschied, Carin R; Castillo, Danielle; Melas, Marilena; Herzog, Josef; Bannon, Sarah; Cruz-Correa, Marcia; Lynch, Patrick; Solomon, Ilana; Gruber, Stephen B; Weitzel, Jeffrey N

2017-04-01

Lynch syndrome (LS), the most common hereditary colorectal cancer syndrome, is caused by mismatch repair (MMR) gene mutations. However, data about MMR mutations in Hispanics are limited. This study aims to describe the spectrum of MMR mutations in Hispanics with LS and explore ancestral origins. This case series involved an IRB-approved retrospective chart review of self-identified Hispanic patients (n = 397) seen for genetic cancer risk assessment at four collaborating academic institutions in California, Texas, and Puerto Rico who were evaluated by MMR genotyping and/or tumor analysis. A literature review was conducted for all mutations identified. Of those who underwent clinical genetic testing (n = 176), 71 had MMR gene mutations. Nine mutations were observed more than once. One third (3/9) of recurrent mutations and two additional mutations (seen only once) were previously reported in Spain, confirming the influence of Spanish ancestry on MMR mutations in Hispanic populations. The recurrent mutations identified (n = 9) included both previously reported mutations as well as unique mutations not in the literature. This is the largest report of Hispanic MMR mutations in North America; however, a larger sample and haplotype analyses are needed to better understand recurrent MMR mutations in Hispanic populations. Copyright © 2017. Published by Elsevier Inc.

Simple detection of germline microsatellite instability for diagnosis of constitutional mismatch repair cancer syndrome.

Science.gov (United States)

Ingham, Danielle; Diggle, Christine P; Berry, Ian; Bristow, Claire A; Hayward, Bruce E; Rahman, Nazneen; Markham, Alexander F; Sheridan, Eamonn G; Bonthron, David T; Carr, Ian M

2013-06-01

Heterozygous mutations in DNA mismatch repair (MMR) genes result in predisposition to colorectal cancer (hereditary nonpolyposis colorectal cancer or Lynch syndrome). Patients with biallelic mutations in these genes, however, present earlier, with constitutional mismatch repair deficiency cancer syndrome (CMMRD), which is characterized by a spectrum of rare childhood malignancies and café-au-lait skin patches. The hallmark of MMR deficiency, microsatellite instability (MSI), is readily detectable in tumor DNA in Lynch syndrome, but is also present in constitutional DNA of CMMRD patients. However, detection of constitutional or germline MSI (gMSI) has hitherto relied on technically difficult assays that are not routinely applicable for clinical diagnosis. Consequently, we have developed a simple high-throughput screening methodology to detect gMSI in CMMRD patients based on the presence of stutter peaks flanking a dinucleotide repeat allele when amplified from patient blood DNA samples. Using the three different microsatellite markers, the gMSI ratio was determined in a cohort of normal individuals and 10 CMMRD patients, with biallelic germline mutations in PMS2 (seven patients), MSH2 (one patient), or MSH6 (two patients). Subjects with either PMS2 or MSH2 mutations were easily identified; however, this measure was not altered in patients with CMMRD due to MSH6 mutation. © 2013 Wiley Periodicals, Inc.

Distinct Clinicopathological Patterns of Mismatch Repair Status in Colorectal Cancer Stratified by KRAS Mutations.

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Wenbin Li

Full Text Available In sporadic colorectal cancer (CRC, the BRAFV600E mutation is associated with deficient mismatch repair (MMR status and inversely associated with to KRAS mutations. In contrast to deficient MMR (dMMR CRC, data on the presence of KRAS oncogenic mutations in proficient MMR (pMMR CRC and their relationship with tumor progression are scarce. We therefore examined the MMR status in combination with KRAS mutations in 913 Chinese patients and correlated the findings obtained with clinical and pathological features. The MMR status was determined based on detection of MLH1, MSH2, MSH6 and PMS2 expression. KRAS mutation and dMMR status were detected in 36.9% and 7.5% of cases, respectively. Four subtypes were determined by MMR and KRAS mutation status: KRAS (+/pMMR (34.0%, KRAS (+/dMMR (2.9%, KRAS (-/pMMR (58.5% and KRAS (-/dMMR (4.6%. A higher percentage of pMMR tumors with KRAS mutation were most likely to be female (49.0%, proximal located (45.5%, a mucinous histology (38.4%, and to have increased lymph node metastasis (60.3%, compared with pMMR tumors without BRAFV600E and KRAS mutations (36.0%, 29.3%, 29.4% and 50.7%, respectively; all P < 0.01. To the contrary, compared with those with KRAS(-/dMMR tumors, patients with KRAS(+/dMMR tumors demonstrated no statistically significant differences in gender, tumor location, pT depth of invasion, lymph node metastasis, pTNM stage, and histologic grade. This study revealed that specific epidemiologic and clinicopathologic characteristics are associated with MMR status stratified by KRAS mutation. Knowledge of MMR and KRAS mutation status may enhance molecular pathologic staging of CRC patients and metastatic progression in CRC can be estimated based on the combination of these biomarkers.

E. coli mismatch repair enhances AT-to-GC mutagenesis caused by alkylating agents.

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Nakano, Kota; Yamada, Yoko; Takahashi, Eizo; Arimoto, Sakae; Okamoto, Keinosuke; Negishi, Kazuo; Negishi, Tomoe

2017-03-01

Alkylating agents are known to induce the formation of O 6 -alkylguanine (O 6 -alkG) and O 4 -alkylthymine (O 4 -alkT) in DNA. These lesions have been widely investigated as major sources of mutations. We previously showed that mismatch repair (MMR) facilitates the suppression of GC-to-AT mutations caused by O 6 -methylguanine more efficiently than the suppression of GC-to-AT mutations caused by O 6 -ethylguanine. However, the manner by which O 4 -alkyT lesions are repaired remains unclear. In the present study, we investigated the repair pathway involved in the repair of O 4 -alkT. The E. coli CC106 strain, which harbors Δprolac in its genomic DNA and carries the F'CC106 episome, can be used to detect AT-to-GC reverse-mutation of the gene encoding β-galactosidase. Such AT-to-GC mutations should be induced through the formation of O 4 -alkT at AT base pairs. As expected, an O 6 -alkylguanine-DNA alkyltransferase (AGT) -deficient CC106 strain, which is defective in both ada and agt genes, exhibited elevated mutant frequencies in the presence of methylating agents and ethylating agents. However, in the UvrA-deficient strain, the methylating agents were less mutagenic than in wild-type, while ethylating agents were more mutagenic than in wild-type, as observed with agents that induce O 6 -alkylguanine modifications. Unexpectedly, the mutant frequencies decreased in a MutS-deficient strain, and a similar tendency was observed in MutL- or MutH-deficient strains. Thus, MMR appears to promote mutation at AT base pairs. Similar results were obtained in experiments employing double-mutant strains harboring defects in both MMR and AGT, or MMR and NER. E. coli MMR enhances AT-to-GC mutagenesis, such as that caused by O 4 -alkylthymine. We hypothesize that the MutS protein recognizes the O 4 -alkT:A base pair more efficiently than O 4 -alkT:G. Such a distinction would result in misincorporation of G at the O 4 -alkT site, followed by higher mutation frequencies in wild

Low frequency of defective mismatch repair in a population-based series of upper urothelial carcinoma

Directory of Open Access Journals (Sweden)

Isfoss Björn L

2005-03-01

Full Text Available Abstract Background Upper urothelial cancer (UUC, i.e. transitional cell carcinomas of the renal pelvis and the ureter, occur at an increased frequency in patients with hereditary nonpolyposis colorectal cancer (HNPCC. Defective mismatch repair (MMR specifically characterizes HNPCC-associated tumors, but also occurs in subsets of some sporadic tumors, e.g. in gastrointestinal cancer and endometrial cancer. Methods We assessed the contribution of defective MMR to the development of UUC in a population-based series from the southern Swedish Cancer Registry, through microsatellite instability (MSI analysis and immunohistochemical evaluation of expression of the MMR proteins MLH1, PMS2, MSH2, and MSH6. Results A MSI-high phenotype was identified in 9/216 (4% successfully analyzed patients and a MSI-low phenotype in 5/216 (2%. Loss of MMR protein immunostaining was found in 11/216 (5% tumors, and affected most commonly MSH2 and MSH6. Conclusion This population-based series indicates that somatic MMR inactivation is a minor pathway in the development of UUC, but tumors that display defective MMR are, based on the immunohistochemical expression pattern, likely to be associated with HNPCC.

Association of common variants in mismatch repair genes and breast cancer susceptibility: a multigene study

International Nuclear Information System (INIS)

Conde, João; Silva, Susana N; Azevedo, Ana P; Teixeira, Valdemar; Pina, Julieta Esperança; Rueff, José; Gaspar, Jorge F

2009-01-01

MMR is responsible for the repair of base-base mismatches and insertion/deletion loops. Besides this, MMR is also associated with an anti-recombination function, suppressing homologous recombination. Losses of heterozygosity and/or microsatellite instability have been detected in a large number of skin samples from breast cancer patients, suggesting a potential role of MMR in breast cancer susceptibility. We carried out a hospital-based case-control study in a Caucasian Portuguese population (287 cases and 547 controls) to estimate the susceptibility to non-familial breast cancer associated with some polymorphisms in mismatch repair genes (MSH3, MSH4, MSH6, MLH1, MLH3, PMS1 and MUTYH). Using unconditional logistic regression we found that MLH3 (L844P, G>A) polymorphism GA (Leu/Pro) and AA (Pro/Pro) genotypes were associated with a decreased risk: OR = 0.65 (0.45-0.95) (p = 0.03) and OR = 0.62 (0.41-0.94) (p = 0.03), respectively. Analysis of two-way SNP interaction effects on breast cancer revealed two potential associations to breast cancer susceptibility: MSH3 Ala1045Thr/MSH6 Gly39Glu - AA/TC [OR = 0.43 (0.21-0.83), p = 0.01] associated with a decreased risk; and MSH4 Ala97Thr/MLH3 Leu844Pro - AG/AA [OR = 2.35 (1.23-4.49), p = 0.01], GG/AA [OR = 2.11 (1.12-3,98), p = 0.02], and GG/AG [adjusted OR = 1.88 (1.12-3.15), p = 0.02] all associated with an increased risk for breast cancer. It is possible that some of these common variants in MMR genes contribute significantly to breast cancer susceptibility. However, further studies with a large sample size will be needed to support our results

Association of common variants in mismatch repair genes and breast cancer susceptibility: a multigene study

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Pina Julieta

2009-09-01

Full Text Available Abstract Background MMR is responsible for the repair of base-base mismatches and insertion/deletion loops. Besides this, MMR is also associated with an anti-recombination function, suppressing homologous recombination. Losses of heterozygosity and/or microsatellite instability have been detected in a large number of skin samples from breast cancer patients, suggesting a potential role of MMR in breast cancer susceptibility. Methods We carried out a hospital-based case-control study in a Caucasian Portuguese population (287 cases and 547 controls to estimate the susceptibility to non-familial breast cancer associated with some polymorphisms in mismatch repair genes (MSH3, MSH4, MSH6, MLH1, MLH3, PMS1 and MUTYH. Results Using unconditional logistic regression we found that MLH3 (L844P, G>A polymorphism GA (Leu/Pro and AA (Pro/Pro genotypes were associated with a decreased risk: OR = 0.65 (0.45-0.95 (p = 0.03 and OR = 0.62 (0.41-0.94 (p = 0.03, respectively. Analysis of two-way SNP interaction effects on breast cancer revealed two potential associations to breast cancer susceptibility: MSH3 Ala1045Thr/MSH6 Gly39Glu - AA/TC [OR = 0.43 (0.21-0.83, p = 0.01] associated with a decreased risk; and MSH4 Ala97Thr/MLH3 Leu844Pro - AG/AA [OR = 2.35 (1.23-4.49, p = 0.01], GG/AA [OR = 2.11 (1.12-3,98, p = 0.02], and GG/AG [adjusted OR = 1.88 (1.12-3.15, p = 0.02] all associated with an increased risk for breast cancer. Conclusion It is possible that some of these common variants in MMR genes contribute significantly to breast cancer susceptibility. However, further studies with a large sample size will be needed to support our results.

Mismatch repair deficiency does not enhance ENU mutagenesis in the zebrafish germ line.

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Feitsma, Harma; de Bruijn, Ewart; van de Belt, Jose; Nijman, Isaac J; Cuppen, Edwin

2008-07-01

S(N)1-type alkylating agents such as N-ethyl-N-nitrosourea (ENU) are very potent mutagens. They act by transferring their alkyl group to DNA bases, which, upon mispairing during replication, can cause single base pair mutations in the next replication cycle. As DNA mismatch repair (MMR) proteins are involved in the recognition of alkylation damage, we hypothesized that ENU-induced mutation rates could be increased in a MMR-deficient background, which would be beneficial for mutagenesis approaches. We applied a standard ENU mutagenesis protocol to adult zebrafish deficient in the MMR gene msh6 and heterozygous controls to study the effect of MMR on ENU-induced DNA damage. Dose-dependent lethality was found to be similar for homozygous and heterozygous mutants, indicating that there is no difference in ENU resistance. Mutation discovery by high-throughput dideoxy resequencing of genomic targets in outcrossed progeny of the mutagenized fish did also not reveal any differences in germ line mutation frequency. These results may indicate that the maximum mutation load for zebrafish has been reached with the currently used, highly optimized ENU mutagenesis protocol. Alternatively, the MMR system in the zebrafish germ line may be saturated very rapidly, thereby having a limited effect on high-dose ENU mutagenesis.

DNA mismatch repair protein deficient non-neoplastic colonic crypts: a novel indicator of Lynch syndrome.

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Pai, Rish K; Dudley, Beth; Karloski, Eve; Brand, Randall E; O'Callaghan, Neil; Rosty, Christophe; Buchanan, Daniel D; Jenkins, Mark A; Thibodeau, Stephen N; French, Amy J; Lindor, Noralane M; Pai, Reetesh K

2018-06-08

Lynch syndrome is the most common form of hereditary colorectal carcinoma. However, establishing the diagnosis of Lynch syndrome is challenging, and ancillary studies that distinguish between sporadic DNA mismatch repair (MMR) protein deficiency and Lynch syndrome are needed, particularly when germline mutation studies are inconclusive. The aim of this study was to determine if MMR protein-deficient non-neoplastic intestinal crypts can help distinguish between patients with and without Lynch syndrome. We evaluated the expression of MMR proteins in non-neoplastic intestinal mucosa obtained from colorectal surgical resection specimens from patients with Lynch syndrome-associated colorectal carcinoma (n = 52) and patients with colorectal carcinoma without evidence of Lynch syndrome (n = 70), including sporadic MMR protein-deficient colorectal carcinoma (n = 30), MMR protein proficient colorectal carcinoma (n = 30), and "Lynch-like" syndrome (n = 10). MMR protein-deficient non-neoplastic colonic crypts were identified in 19 of 122 (16%) patients. MMR protein-deficient colonic crypts were identified in 18 of 52 (35%) patients with Lynch syndrome compared to only 1 of 70 (1%) patients without Lynch syndrome (p Lynch-like" syndrome and harbored two MSH2-deficient non-neoplastic colonic crypts. MMR protein-deficient non-neoplastic colonic crypts were not identified in patients with sporadic MMR protein-deficient or MMR protein proficient colorectal carcinoma. Our findings suggest that MMR protein-deficient colonic crypts are a novel indicator of Lynch syndrome, and evaluation for MMR protein-deficient crypts may be a helpful addition to Lynch syndrome diagnostics.

DREMECELS: A Curated Database for Base Excision and Mismatch Repair Mechanisms Associated Human Malignancies.

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Ankita Shukla

Full Text Available DNA repair mechanisms act as a warrior combating various damaging processes that ensue critical malignancies. DREMECELS was designed considering the malignancies with frequent alterations in DNA repair pathways, that is, colorectal and endometrial cancers, associated with Lynch syndrome (also known as HNPCC. Since lynch syndrome carries high risk (~40-60% for both cancers, therefore we decided to cover all three diseases in this portal. Although a large population is presently affected by these malignancies, many resources are available for various cancer types but no database archives information on the genes specifically for only these cancers and disorders. The database contains 156 genes and two repair mechanisms, base excision repair (BER and mismatch repair (MMR. Other parameters include some of the regulatory processes that have roles in these disease progressions due to incompetent repair mechanisms, specifically BER and MMR. However, our unique database mainly provides qualitative and quantitative information on these cancer types along with methylation, drug sensitivity, miRNAs, copy number variation (CNV and somatic mutations data. This database would serve the scientific community by providing integrated information on these disease types, thus sustaining diagnostic and therapeutic processes. This repository would serve as an excellent accompaniment for researchers and biomedical professionals and facilitate in understanding such critical diseases. DREMECELS is publicly available at http://www.bioinfoindia.org/dremecels.

Both hMutSα and hMutSß DNA mismatch repair complexes participate in 5-fluorouracil cytotoxicity.

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Akihiro Tajima

Full Text Available Patients with advanced microsatellite unstable colorectal cancers do not show a survival benefit from 5-fluorouracil (5-FU-based chemotherapy. We and others have shown that the DNA mismatch repair (MMR complex hMutSα binds 5-FU incorporated into DNA. Although hMutSß is known to interact with interstrand crosslinks (ICLs induced by drugs such as cisplatin and psoralen, it has not been demonstrated to interact with 5-FU incorporated into DNA. Our aim was to examine if hMutSß plays a role in 5-FU recognition.We compared the normalized growth of 5-FU treated cells containing either or both mismatch repair complexes using MTT and clonogenic assays. We utilized oligonucleotides containing 5-FU and purified baculovirus-synthesized hMutSα and hMutSß in electromobility shift assays (EMSA and further analyzed binding using surface plasmon resonance.MTT and clonogenic assays after 5-FU treatment demonstrated the most cytotoxicity in cells with both hMutSα and hMutSß, intermediate cytotoxicity in cells with hMutSα alone, and the least cytotoxicity in cells with hMutSß alone, hMutSß binds 5-FU-modified DNA, but its relative binding is less than the binding of 5-FU-modified DNA by hMutSα.Cytotoxicity induced by 5-FU is dependent on intact DNA MMR, with relative cell death correlating directly with hMutSα and/or hMutSß 5-FU binding ability (hMutSα>hMutSß. The MMR complexes provide a hierarchical chemosensitivity for 5-FU cell death, and may have implications for treatment of patients with certain MMR-deficient tumors.

Functional analysis of rare variants in mismatch repair proteins augments results from computation-based predictive methods

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Arora, Sanjeevani; Huwe, Peter J.; Sikder, Rahmat; Shah, Manali; Browne, Amanda J.; Lesh, Randy; Nicolas, Emmanuelle; Deshpande, Sanat; Hall, Michael J.; Dunbrack, Roland L.; Golemis, Erica A.

2017-01-01

ABSTRACT The cancer-predisposing Lynch Syndrome (LS) arises from germline mutations in DNA mismatch repair (MMR) genes, predominantly MLH1, MSH2, MSH6, and PMS2. A major challenge for clinical diagnosis of LS is the frequent identification of variants of uncertain significance (VUS) in these genes, as it is often difficult to determine variant pathogenicity, particularly for missense variants. Generic programs such as SIFT and PolyPhen-2, and MMR gene-specific programs such as PON-MMR and MAPP-MMR, are often used to predict deleterious or neutral effects of VUS in MMR genes. We evaluated the performance of multiple predictive programs in the context of functional biologic data for 15 VUS in MLH1, MSH2, and PMS2. Using cell line models, we characterized VUS predicted to range from neutral to pathogenic on mRNA and protein expression, basal cellular viability, viability following treatment with a panel of DNA-damaging agents, and functionality in DNA damage response (DDR) signaling, benchmarking to wild-type MMR proteins. Our results suggest that the MMR gene-specific classifiers do not always align with the experimental phenotypes related to DDR. Our study highlights the importance of complementary experimental and computational assessment to develop future predictors for the assessment of VUS. PMID:28494185

DNA mismatch repair deficiency accelerates lung neoplasm development in K-rasLA1/+ mice: a brief report

International Nuclear Information System (INIS)

Downey, Charlene M; Jirik, Frank R

2015-01-01

Inherited as well as acquired deficiencies in specific DNA mismatch repair (MMR) components are associated with the development of a wide range of benign and malignant neoplasms. Loss of key members such as MSH2 and MLH1 severely cripples the ability of the cell to recognize and correct such lesions as base:base mismatches and replicative DNA polymerase errors such as slippages at repetitive sequences. Genomic instability resulting from MMR deficiency not only predisposes cells to malignant transformation but may also promote tumor progression. To test the latter, we interbred Msh2 −/− mice with the K-ras LA1/+ transgenic line that spontaneously develops a range of premalignant and malignant lung lesions. Compared to K-ras LA1/+ mice, K-ras LA1/+ ; Msh2 −/− mice developed lung adenomas and adenocarcinomas at an increased frequency and also demonstrated evidence of accelerated adenocarcinoma growth. Since MMR defects have been identified in some human lung cancers, the mutant mice may not only be of preclinical utility but they will also be useful in identifying gene alterations able to act in concert with Kras mutants to promote tumor progression

Risk of colorectal cancer for people with a mutation in both a MUTYH and a DNA mismatch repair gene

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Win, Aung Ko; Reece, Jeanette C.; Buchanan, Daniel D.; Clendenning, Mark; Young, Joanne P.; Cleary, Sean P.; Kim, Hyeja; Cotterchio, Michelle; Dowty, James G.; MacInnis, Robert J.; Tucker, Katherine M.; Winship, Ingrid M.; Macrae, Finlay A.; Burnett, Terrilea; Le Marchand, Loïc; Casey, Graham; Haile, Robert W.; Newcomb, Polly A.; Thibodeau, Stephen N.; Lindor, Noralane M.; Hopper, John L.; Gallinger, Steven; Jenkins, Mark A.

2015-01-01

The base excision repair protein, MUTYH, functionally interacts with the DNA mismatch repair (MMR) system. As genetic testing moves from testing one gene at a time, to gene panel and whole exome next generation sequencing approaches, understanding the risk associated with co-existence of germline mutations in these genes will be important for clinical interpretation and management. From the Colon Cancer Family Registry, we identified 10 carriers who had both a MUTYH mutation (6 with c.1187G>A p.(Gly396Asp), 3 with c.821G>A p.(Arg274Gln), and 1 with c.536A>G p.(Tyr179Cys)) and a MMR gene mutation (3 in MLH1, 6 in MSH2, and 1 in PMS2), 375 carriers of a single (monoallelic) MUTYH mutation alone, and 469 carriers of a MMR gene mutation alone. Of the 10 carriers of both gene mutations, 8 were diagnosed with colorectal cancer. Using a weighted cohort analysis, we estimated that risk of colorectal cancer for carriers of both a MUTYH and a MMR gene mutation was substantially higher than that for carriers of a MUTYH mutation alone [hazard ratio (HR) 21.5, 95 % confidence interval (CI) 9.19–50.1; p colorectal cancer for carriers of a MMR gene mutation alone. Our finding suggests MUTYH mutation testing in MMR gene mutation carriers is not clinically informative. PMID:26202870

Diagnostic criteria for constitutional mismatch repair deficiency syndrome

DEFF Research Database (Denmark)

Wimmer, Katharina; Kratz, Christian P; Vasen, Hans F A

2014-01-01

Constitutional mismatch repair deficiency (CMMRD) syndrome is a distinct childhood cancer predisposition syndrome that results from biallelic germline mutations in one of the four MMR genes, MLH1, MSH2, MSH6 or PMS2. The tumour spectrum is very broad, including mainly haematological, brain....... They include multiple hyperpigmented and hypopigmented skin areas, brain malformations, pilomatricomas, a second childhood malignancy, a Lynch syndrome (LS)-associated tumour in a relative and parental consanguinity. According to the scoring system, CMMRD should be suspected in any cancer patient who reaches...... patient. Tumours highly specific for CMMRD syndrome are assigned three points, malignancies overrepresented in CMMRD two points and all other malignancies one point. According to their specificity for CMMRD and their frequency in the general population, additional features are weighted with 1-2 points...

Dominant mutations in S. cerevisiae PMS1 identify the Mlh1-Pms1 endonuclease active site and an exonuclease 1-independent mismatch repair pathway.

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Smith, Catherine E; Mendillo, Marc L; Bowen, Nikki; Hombauer, Hans; Campbell, Christopher S; Desai, Arshad; Putnam, Christopher D; Kolodner, Richard D

2013-10-01

Lynch syndrome (hereditary nonpolypsis colorectal cancer or HNPCC) is a common cancer predisposition syndrome. Predisposition to cancer in this syndrome results from increased accumulation of mutations due to defective mismatch repair (MMR) caused by a mutation in one of the mismatch repair genes MLH1, MSH2, MSH6 or PMS2/scPMS1. To better understand the function of Mlh1-Pms1 in MMR, we used Saccharomyces cerevisiae to identify six pms1 mutations (pms1-G683E, pms1-C817R, pms1-C848S, pms1-H850R, pms1-H703A and pms1-E707A) that were weakly dominant in wild-type cells, which surprisingly caused a strong MMR defect when present on low copy plasmids in an exo1Δ mutant. Molecular modeling showed these mutations caused amino acid substitutions in the metal coordination pocket of the Pms1 endonuclease active site and biochemical studies showed that they inactivated the endonuclease activity. This model of Mlh1-Pms1 suggested that the Mlh1-FERC motif contributes to the endonuclease active site. Consistent with this, the mlh1-E767stp mutation caused both MMR and endonuclease defects similar to those caused by the dominant pms1 mutations whereas mutations affecting the predicted metal coordinating residue Mlh1-C769 had no effect. These studies establish that the Mlh1-Pms1 endonuclease is required for MMR in a previously uncharacterized Exo1-independent MMR pathway.

Dominant mutations in S. cerevisiae PMS1 identify the Mlh1-Pms1 endonuclease active site and an exonuclease 1-independent mismatch repair pathway.

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Catherine E Smith

2013-10-01

Full Text Available Lynch syndrome (hereditary nonpolypsis colorectal cancer or HNPCC is a common cancer predisposition syndrome. Predisposition to cancer in this syndrome results from increased accumulation of mutations due to defective mismatch repair (MMR caused by a mutation in one of the mismatch repair genes MLH1, MSH2, MSH6 or PMS2/scPMS1. To better understand the function of Mlh1-Pms1 in MMR, we used Saccharomyces cerevisiae to identify six pms1 mutations (pms1-G683E, pms1-C817R, pms1-C848S, pms1-H850R, pms1-H703A and pms1-E707A that were weakly dominant in wild-type cells, which surprisingly caused a strong MMR defect when present on low copy plasmids in an exo1Δ mutant. Molecular modeling showed these mutations caused amino acid substitutions in the metal coordination pocket of the Pms1 endonuclease active site and biochemical studies showed that they inactivated the endonuclease activity. This model of Mlh1-Pms1 suggested that the Mlh1-FERC motif contributes to the endonuclease active site. Consistent with this, the mlh1-E767stp mutation caused both MMR and endonuclease defects similar to those caused by the dominant pms1 mutations whereas mutations affecting the predicted metal coordinating residue Mlh1-C769 had no effect. These studies establish that the Mlh1-Pms1 endonuclease is required for MMR in a previously uncharacterized Exo1-independent MMR pathway.

Role of APC and DNA mismatch repair genes in the development of colorectal cancers

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Roy Deodutta

2003-12-01

Full Text Available Abstract Colorectal cancer is the third most common cause of cancer-related death in both men and women in the western hemisphere. According to the American Cancer Society, an estimated 105,500 new cases of colon cancer with 57,100 deaths will occur in the U.S. in 2003, accounting for about 10% of cancer deaths. Among the colon cancer patients, hereditary risk contributes approximately 20%. The main inherited colorectal cancers are the familial adenomatous polyposis (FAP and the hereditary nonpolyposis colorectal cancers (HNPCC. The FAP and HNPCC are caused due to mutations in the adenomatous polyposis coli (APC and DNA mismatch repair (MMR genes. The focus of this review is to summarize the functions of APC and MMR gene products in the development of colorectal cancers.

Loss of DNA mismatch repair imparts a selective advantage in planarian adult stem cells.

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Jessica P Hollenbach

Full Text Available Lynch syndrome (LS leads to an increased risk of early-onset colorectal and other types of cancer and is caused by germline mutations in DNA mismatch repair (MMR genes. Loss of MMR function results in a mutator phenotype that likely underlies its role in tumorigenesis. However, loss of MMR also results in the elimination of a DNA damage-induced checkpoint/apoptosis activation barrier that may allow damaged cells to grow unchecked. A fundamental question is whether loss of MMR provides pre-cancerous stem cells an immediate selective advantage in addition to establishing a mutator phenotype. To test this hypothesis in an in vivo system, we utilized the planarian Schmidtea mediterranea which contains a significant population of identifiable adult stem cells. We identified a planarian homolog of human MSH2, a MMR gene which is mutated in 38% of LS cases. The planarian Smed-msh2 is expressed in stem cells and some progeny. We depleted Smed-msh2 mRNA levels by RNA-interference and found a striking survival advantage in these animals treated with a cytotoxic DNA alkylating agent compared to control animals. We demonstrated that this tolerance to DNA damage is due to the survival of mitotically active, MMR-deficient stem cells. Our results suggest that loss of MMR provides an in vivo survival advantage to the stem cell population in the presence of DNA damage that may have implications for tumorigenesis.

The human cyclin B1 protein modulates sensitivity of DNA mismatch repair deficient prostate cancer cell lines to alkylating agents.

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Rasmussen, L J; Rasmussen, M; Lützen, A; Bisgaard, H C; Singh, K K

2000-05-25

DNA damage caused by alkylating agents results in a G2 checkpoint arrest. DNA mismatch repair (MMR) deficient cells are resistant to killing by alkylating agents and are unable to arrest the cell cycle in G2 phase after alkylation damage. We investigated the response of two MMR-deficient prostate cancer cell lines DU145 and LNCaP to the alkylating agent MNNG. Our studies reveal that DU145 cancer cells are more sensitive to killing by MNNG than LNCaP. Investigation of the underlying reasons for lower resistance revealed that the DU145 cells contain low endogenous levels of cyclin B1. We provide direct evidence that the endogenous level of cyclin B1 modulates the sensitivity of MMR-deficient prostate cancer cells to alkylating agents.

Tumor mismatch repair immunohistochemistry and DNA MLH1 methylation testing of patients with endometrial cancer diagnosed at age younger than 60 years optimizes triage for population-level germline mismatch repair gene mutation testing.

Science.gov (United States)

Buchanan, Daniel D; Tan, Yen Y; Walsh, Michael D; Clendenning, Mark; Metcalf, Alexander M; Ferguson, Kaltin; Arnold, Sven T; Thompson, Bryony A; Lose, Felicity A; Parsons, Michael T; Walters, Rhiannon J; Pearson, Sally-Ann; Cummings, Margaret; Oehler, Martin K; Blomfield, Penelope B; Quinn, Michael A; Kirk, Judy A; Stewart, Colin J; Obermair, Andreas; Young, Joanne P; Webb, Penelope M; Spurdle, Amanda B

2014-01-10

Clinicopathologic data from a population-based endometrial cancer cohort, unselected for age or family history, were analyzed to determine the optimal scheme for identification of patients with germline mismatch repair (MMR) gene mutations. Endometrial cancers from 702 patients recruited into the Australian National Endometrial Cancer Study (ANECS) were tested for MMR protein expression using immunohistochemistry (IHC) and for MLH1 gene promoter methylation in MLH1-deficient cases. MMR mutation testing was performed on germline DNA of patients with MMR-protein deficient tumors. Prediction of germline mutation status was compared for combinations of tumor characteristics, age at diagnosis, and various clinical criteria (Amsterdam, Bethesda, Society of Gynecologic Oncology, ANECS). Tumor MMR-protein deficiency was detected in 170 (24%) of 702 cases. Germline testing of 158 MMR-deficient cases identified 22 truncating mutations (3% of all cases) and four unclassified variants. Tumor MLH1 methylation was detected in 99 (89%) of 111 cases demonstrating MLH1/PMS2 IHC loss; all were germline MLH1 mutation negative. A combination of MMR IHC plus MLH1 methylation testing in women younger than 60 years of age at diagnosis provided the highest positive predictive value for the identification of mutation carriers at 46% versus ≤ 41% for any other criteria considered. Population-level identification of patients with MMR mutation-positive endometrial cancer is optimized by stepwise testing for tumor MMR IHC loss in patients younger than 60 years, tumor MLH1 methylation in individuals with MLH1 IHC loss, and germline mutations in patients exhibiting loss of MSH6, MSH2, or PMS2 or loss of MLH1/PMS2 with absence of MLH1 methylation.

The relationship between the PD-1/PD-L1 pathway and DNA mismatch repair in cervical cancer and its clinical significance

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Feng YC

2018-01-01

Full Text Available Yang-chun Feng,1,2 Wen-li Ji,3 Na Yue,3 Yan-chun Huang,2 Xiu-min Ma1 1Clinical Laboratory Center, The First Affiliated Hospital of Xinjiang Medical University, 2Clinical Laboratory Center, 3Clinical Pathology Center, Tumor Hospital Affiliated to Xinjiang Medical University, Urumqi, People’s Republic of China Background: According to recent clinical observations, deficient DNA mismatch repair (dMMR is capable of improving antitumor effects of the PD-1/PD-L1 pathway, suggesting that dMMR may act as a prognostic indicator of PD-1/PD-L1 antibody drugs. In this study, we examined the dMMR and PD-1/PD-L1 expression, as well as explored the correlation of dMMR status with PD-1/PD-L1 expression in cervical cancer patients, in order to optimize cervical cancer patient selection for PD-1/PD-L1 antibody drug treatment, which is helpful to avoid adverse effects and keep costs manageable. Methods: Sixty-six tissue samples from patients with squamous cell carcinoma were collected, and data of their clinical characteristics were also gathered. Based on these samples, the expression levels of MLH1, MSH2, and PD-L1 in cancer cells were tested by immunohistochemical assay (IHC. Moreover, PD-1/PD-L1 expression in tumor-invading lymphocytes (TILs was detected by IHC as well. Six single-nucleotide-repeat markers of microsatellite instability (MSI, including NR-27, MONO-27, BAT-25, NR-24, NR-21, and BAT-26, were tested by capillary electrophoresis sequencer analysis. According to expression of MLH1, MSH2 and the MSI test, all 66 cases were divided into dMMR or proficient DNA mismatch repair (pMMR groups. The comparisons of dMMR and PD-L1 in cancer cells and of PD-1/PD-L1 in TILs were conducted categorized by age, childbearing history, history of abortion, ethnicity, and cancer cell differentiation subgroup. Furthermore, PD-L1 levels in cancer cells and PD-1/PD-L1 in TILs were analyzed and compared in both dMMR and pMMR subgroups. Results: Of the patient samples, 25

[Constitutional mismatch repair deficiency syndrome

NARCIS (Netherlands)

Jongmans, M.C.J.; Gidding, C.E.M.; Loeffen, J.; Wesseling, P.; Mensenkamp, A.; Hoogerbrugge, N.

2015-01-01

BACKGROUND: Constitutional mismatch repair deficiency (CMMR-D) syndrome is characterised by a significantly increased risk for developing cancer in childhood. It arises when both parents have a mutation in the same mismatch repair gene and pass it on to their child. CASE DESCRIPTION: An 8-year-old

Elevated levels of the mismatch repair protein PMS2 are associated with prostate cancer.

Science.gov (United States)

Norris, Alixanna M; Woodruff, R D; D'Agostino, Ralph B; Clodfelter, Jill E; Scarpinato, Karin Drotschmann

2007-02-01

Defects in mismatch repair (MMR) proteins have been identified in various types of cancer. However, an association with prostate cancer has been controversial. Defective MMR results in genome instability with detrimental consequences that significantly contribute to tumorigenesis. This study determined alterations in key MMR protein levels in prostate cancer with the goal to identify prognostic markers. Prostatectomy samples were immunohistochemically stained and the relative presence or absence of key proteins MSH2, MLH1, and PMS2 determined. Cancer tissue of distinct grades was compared with the normal surrounding tissue. Microsatellite instability (MSI) in altered tissues was determined according to NCI guidelines. In contrast to reports that associate a lack of individual MMR proteins with tumorigenesis, a significant increase in PMS2 levels was identified in PIN lesions and prostate cancer tissue. This elevation in PMS2 was independent of changes in levels in its heterodimeric partner, MLH1. Prostate tumors with elevated levels of PMS2 were genetically unstable, which was corrected by MLH1 co-elevation. This is the first documentation of detrimental consequences associated with the increase in a MMR protein in human cancer. This study recognizes PMS2 elevation as a prognostic marker in pre-neoplastic and prostate cancer lesions. This result has significant implications for future diagnostic and treatment measures. (c) 2006 Wiley-Liss, Inc.

Inhibition of colorectal cancer genomic copy number alterations and chromosomal fragile site tumor suppressor FHIT and WWOX deletions by DNA mismatch repair

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Gelincik, Ozkan; Blecua, Pedro; Edelmann, Winfried; Kucherlapati, Raju; Zhou, Kathy; Jasin, Maria; Gümüş, Zeynep H.; Lipkin, Steven M.

2017-01-01

Homologous recombination (HR) enables precise DNA repair after DNA double strand breaks (DSBs) using identical sequence templates, whereas homeologous recombination (HeR) uses only partially homologous sequences. Homeologous recombination introduces mutations through gene conversion and genomic deletions through single-strand annealing (SSA). DNA mismatch repair (MMR) inhibits HeR, but the roles of mammalian MMR MutL homologues (MLH1, PMS2 and MLH3) proteins in HeR suppression are poorly characterized. Here, we demonstrate that mouse embryonic fibroblasts (MEFs) carrying Mlh1, Pms2, and Mlh3 mutations have higher HeR rates, by using 7,863 uniquely mapping paired direct repeat sequences (DRs) in the mouse genome as endogenous gene conversion and SSA reporters. Additionally, when DSBs are induced by gamma-radiation, Mlh1, Pms2 and Mlh3 mutant MEFs have higher DR copy number alterations (CNAs), including DR CNA hotspots previously identified in mouse MMR-deficient colorectal cancer (dMMR CRC). Analysis of The Cancer Genome Atlas CRC data revealed that dMMR CRCs have higher genome-wide DR HeR rates than MMR proficient CRCs, and that dMMR CRCs have deletion hotspots in tumor suppressors FHIT/WWOX at chromosomal fragile sites FRA3B and FRA16D (which have elevated DSB rates) flanked by paired homologous DRs and inverted repeats (IR). Overall, these data provide novel insights into the MMR-dependent HeR inhibition mechanism and its role in tumor suppression. PMID:29069730

Constitutional mismatch repair deficiency in a healthy child: On the spot diagnosis?

Science.gov (United States)

Suerink, M; Potjer, T P; Versluijs, A B; Ten Broeke, S W; Tops, C M; Wimmer, K; Nielsen, M

2018-01-01

Constitutional mismatch repair deficiency (CMMRD) is a rare, recessively inherited childhood cancer predisposition syndrome caused by biallelic germline mutations in one of the mismatch repair genes. The CMMRD phenotype overlaps with that of neurofibromatosis type 1 (NF1), since many patients have multiple café-au-lait macules (CALM) and other NF1 signs, but no germline NF1 mutations. We report of a case of a healthy 6-year-old girl who fulfilled the diagnostic criteria of NF1 with >6 CALM and freckling. Since molecular genetic testing was unable to confirm the diagnosis of NF1 or Legius syndrome and the patient was a child of consanguineous parents, we suspected CMMRD and found a homozygous PMS2 mutation that impairs MMR function. Current guidelines advise testing for CMMRD only in cancer patients. However, this case illustrates that including CMMRD in the differential diagnosis in suspected sporadic NF1 without causative NF1 or SPRED1 mutations may facilitate identification of CMMRD prior to cancer development. We discuss the advantages and potential risks of this CMMRD testing scenario. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Functional role of DNA mismatch repair gene PMS2 in prostate cancer cells.

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Fukuhara, Shinichiro; Chang, Inik; Mitsui, Yozo; Chiyomaru, Takeshi; Yamamura, Soichiro; Majid, Shahana; Saini, Sharanjot; Deng, Guoren; Gill, Ankurpreet; Wong, Darryn K; Shiina, Hiroaki; Nonomura, Norio; Lau, Yun-Fai C; Dahiya, Rajvir; Tanaka, Yuichiro

2015-06-30

DNA mismatch repair (MMR) enzymes act as proofreading complexes that maintains genomic integrity and MMR-deficient cells show an increased mutation rate. MMR has also been shown to influence cell signaling and the regulation of tumor development. MMR consists of various genes and includes post-meiotic segregation (PMS) 2 which is a vital component of mutL-alpha. In prostate, the functional role of this gene has never been reported and in this study, our aim was to investigate the effect of PMS2 on growth properties of prostate cancer (PCa) cells. Previous studies have shown PMS2 to be deficient in DU145 cells and this lack of expression was confirmed by Western blotting whereas normal prostatic PWR-1E and RWPE-1 cells expressed this gene. PMS2 effects on various growth properties of DU145 were then determined by creating stable gene transfectants. Interestingly, PMS2 caused decreased cell proliferation, migration, invasion, and in vivo growth; and increased apoptosis as compared to vector control. We further analyzed genes affected by PMS2 expression and observe the apoptosis-related TMS1 gene to be significantly upregulated whereas anti-apoptotic BCL2A1 was downregulated. These results demonstrate a functional role for PMS2 to protect against PCa progression by enhancing apoptosis of PCa cells.

Optic pathway glioma as part of a constitutional mismatch-repair deficiency syndrome in a patient meeting the criteria for neurofibromatosis type 1.

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Yeung, Jacky T; Pollack, Ian F; Shah, Sapana; Jaffe, Ronald; Nikiforova, Marina; Jakacki, Regina I

2013-01-01

Patients with constitutional mismatch repair-deficiency (CMMR-D) caused by the biallelic deletions of mismatch repair (MMR) genes have a high likelihood of developing malignancies of the bone marrow, bowel, and brain. Affected individuals often have phenotypic features of neurofibromatosis type 1 (NF-1), including café-au-lait spots. Optic pathway gliomas (OPGs), a common manifestation of NF-1, have not been reported. We report the case of a 3-year-old male with an extensive OPG who met the diagnostic criteria for NF-1. He was subsequently found to have multiple colonic polyps and bi-allelic loss of PMS2. Testing for NF-1 was negative. Copyright © 2012 Wiley Periodicals, Inc.

Prevalence of adenomas and hyperplastic polyps in mismatch repair mutation carriers among CAPP2 participants: report by the colorectal adenoma/carcinoma prevention programme 2

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Liljegren, Annelie; Barker, Gail; Elliott, Faye

2008-01-01

PURPOSE: To determine the prevalence of adenomatous and hyperplastic polyps in a large cohort of individuals with a germline mutation in a mismatch repair (MMR) gene, the major genetic determinant of hereditary nonpolyposis colorectal cancer (HNPCC). These prevalences have been estimated previously...... in smaller studies, and the results have been found to be variable. PATIENTS AND METHODS: Colorectal Adenoma/Carcinoma Prevention Programme 2 trial is a chemoprevention trial in people classified as having HNPCC. The 695 patients with a proven germline MMR mutation and documented screening history before...

Homozygous germ-line mutation of the PMS2 mismatch repair gene: a unique case report of constitutional mismatch repair deficiency (CMMRD)

OpenAIRE

Ramchander, N. C.; Ryan, N. A. J.; Crosbie, E. J.; Evans, D. G.

2017-01-01

BackgroundConstitutional mismatch repair deficiency syndrome results from bi-allelic inheritance of mutations affecting the key DNA mismatch repair genes: MLH1, MSH2, MSH6 or PMS2. Individuals with bi-allelic mutations have a dysfunctional mismatch repair system from birth; as a result, constitutional mismatch repair deficiency syndrome is characterised by early onset malignancies. Fewer than 150 cases have been reported in the literature over the past 20 years. This is the first report of th...

Mismatch repair gene mutation spectrum in the Swedish Lynch syndrome population

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Lagerstedt-Robinson, Kristina; Rohlin, Anna; Aravidis, Christos

2016-01-01

Lynch syndrome caused by constitutional mismatch‑repair defects is one of the most common hereditary cancer syndromes with a high risk for colorectal, endometrial, ovarian and urothelial cancer. Lynch syndrome is caused by mutations in the mismatch repair (MMR) genes i.e., MLH1, MSH2, MSH6 and PMS2...... Lynch syndrome families. These mutations affected MLH1 in 40%, MSH2 in 36%, MSH6 in 18% and PMS2 in 6% of the families. A large variety of mutations were identified with splice site mutations being the most common mutation type in MLH1 and frameshift mutations predominating in MSH2 and MSH6. Large...... deletions of one or several exons accounted for 21% of the mutations in MLH1 and MSH2 and 22% in PMS2, but were rare (4%) in MSH6. In 66% of the Lynch syndrome families the variants identified were private and the effect from founder mutations was limited and predominantly related to a Finnish founder...

Pms2 and uracil-DNA glycosylases act jointly in the mismatch repair pathway to generate Ig gene mutations at A-T base pairs.

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Girelli Zubani, Giulia; Zivojnovic, Marija; De Smet, Annie; Albagli-Curiel, Olivier; Huetz, François; Weill, Jean-Claude; Reynaud, Claude-Agnès; Storck, Sébastien

2017-04-03

During somatic hypermutation (SHM) of immunoglobulin genes, uracils introduced by activation-induced cytidine deaminase are processed by uracil-DNA glycosylase (UNG) and mismatch repair (MMR) pathways to generate mutations at G-C and A-T base pairs, respectively. Paradoxically, the MMR-nicking complex Pms2/Mlh1 is apparently dispensable for A-T mutagenesis. Thus, how detection of U:G mismatches is translated into the single-strand nick required for error-prone synthesis is an open question. One model proposed that UNG could cooperate with MMR by excising a second uracil in the vicinity of the U:G mismatch, but it failed to explain the low impact of UNG inactivation on A-T mutagenesis. In this study, we show that uracils generated in the G1 phase in B cells can generate equal proportions of A-T and G-C mutations, which suggests that UNG and MMR can operate within the same time frame during SHM. Furthermore, we show that Ung -/- Pms2 -/- mice display a 50% reduction in mutations at A-T base pairs and that most remaining mutations at A-T bases depend on two additional uracil glycosylases, thymine-DNA glycosylase and SMUG1. These results demonstrate that Pms2/Mlh1 and multiple uracil glycosylases act jointly, each one with a distinct strand bias, to enlarge the immunoglobulin gene mutation spectrum from G-C to A-T bases. © 2017 Girelli Zubani et al.

The Rate and Spectrum of Spontaneous Mutations in Mycobacterium smegmatis, a Bacterium Naturally Devoid of the Postreplicative Mismatch Repair Pathway.

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Kucukyildirim, Sibel; Long, Hongan; Sung, Way; Miller, Samuel F; Doak, Thomas G; Lynch, Michael

2016-07-07

Mycobacterium smegmatis is a bacterium that is naturally devoid of known postreplicative DNA mismatch repair (MMR) homologs, mutS and mutL, providing an opportunity to investigate how the mutation rate and spectrum has evolved in the absence of a highly conserved primary repair pathway. Mutation accumulation experiments of M. smegmatis yielded a base-substitution mutation rate of 5.27 × 10(-10) per site per generation, or 0.0036 per genome per generation, which is surprisingly similar to the mutation rate in MMR-functional unicellular organisms. Transitions were found more frequently than transversions, with the A:T→G:C transition rate significantly higher than the G:C→A:T transition rate, opposite to what is observed in most studied bacteria. We also found that the transition-mutation rate of M. smegmatis is significantly lower than that of other naturally MMR-devoid or MMR-knockout organisms. Two possible candidates that could be responsible for maintaining high DNA fidelity in this MMR-deficient organism are the ancestral-like DNA polymerase DnaE1, which contains a highly efficient DNA proofreading histidinol phosphatase (PHP) domain, and/or the existence of a uracil-DNA glycosylase B (UdgB) homolog that might protect the GC-rich M. smegmatis genome against DNA damage arising from oxidation or deamination. Our results suggest that M. smegmatis has a noncanonical Dam (DNA adenine methylase) methylation system, with target motifs differing from those previously reported. The mutation features of M. smegmatis provide further evidence that genomes harbor alternative routes for improving replication fidelity, even in the absence of major repair pathways. Copyright © 2016 Kucukyildirim et al.

The Rate and Spectrum of Spontaneous Mutations in Mycobacterium smegmatis, a Bacterium Naturally Devoid of the Postreplicative Mismatch Repair Pathway

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Sibel Kucukyildirim

2016-07-01

Full Text Available Mycobacterium smegmatis is a bacterium that is naturally devoid of known postreplicative DNA mismatch repair (MMR homologs, mutS and mutL, providing an opportunity to investigate how the mutation rate and spectrum has evolved in the absence of a highly conserved primary repair pathway. Mutation accumulation experiments of M. smegmatis yielded a base-substitution mutation rate of 5.27 × 10−10 per site per generation, or 0.0036 per genome per generation, which is surprisingly similar to the mutation rate in MMR-functional unicellular organisms. Transitions were found more frequently than transversions, with the A:T→G:C transition rate significantly higher than the G:C→A:T transition rate, opposite to what is observed in most studied bacteria. We also found that the transition-mutation rate of M. smegmatis is significantly lower than that of other naturally MMR-devoid or MMR-knockout organisms. Two possible candidates that could be responsible for maintaining high DNA fidelity in this MMR-deficient organism are the ancestral-like DNA polymerase DnaE1, which contains a highly efficient DNA proofreading histidinol phosphatase (PHP domain, and/or the existence of a uracil-DNA glycosylase B (UdgB homolog that might protect the GC-rich M. smegmatis genome against DNA damage arising from oxidation or deamination. Our results suggest that M. smegmatis has a noncanonical Dam (DNA adenine methylase methylation system, with target motifs differing from those previously reported. The mutation features of M. smegmatis provide further evidence that genomes harbor alternative routes for improving replication fidelity, even in the absence of major repair pathways.

Complex relationship between mismatch repair proteins and MBD4 during immunoglobulin class switch recombination.

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Grigera, Fernando; Bellacosa, Alfonso; Kenter, Amy L

2013-01-01

Mismatch repair (MMR) safeguards against genomic instability and is required for efficient Ig class switch recombination (CSR). Methyl CpG binding domain protein 4 (MBD4) binds to MutL homologue 1 (MLH1) and controls the post-transcriptional level of several MMR proteins, including MutS homologue 2 (MSH2). We show that in WT B cells activated for CSR, MBD4 is induced and interacts with MMR proteins, thereby implying a role for MBD4 in CSR. However, CSR is in the normal range in Mbd4 deficient mice deleted for exons 2-5 despite concomitant reduction of MSH2. We show by comparison in Msh2(+/-) B cells that a two-fold reduction of MSH2 and MBD4 proteins is correlated with impaired CSR. It is therefore surprising that CSR occurs at normal frequencies in the Mbd4 deficient B cells where MSH2 is reduced. We find that a variant Mbd4 transcript spanning exons 1,6-8 is expressed in Mbd4 deficient B cells. This transcript can be ectopically expressed and produces a truncated MBD4 peptide. Thus, the 3' end of the Mbd4 locus is not silent in Mbd4 deficient B cells and may contribute to CSR. Our findings highlight a complex relationship between MBD4 and MMR proteins in B cells and a potential reconsideration of their role in CSR.

Mlh2 is an accessory factor for DNA mismatch repair in Saccharomyces cerevisiae.

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Christopher S Campbell

2014-05-01

Full Text Available In Saccharomyces cerevisiae, the essential mismatch repair (MMR endonuclease Mlh1-Pms1 forms foci promoted by Msh2-Msh6 or Msh2-Msh3 in response to mispaired bases. Here we analyzed the Mlh1-Mlh2 complex, whose role in MMR has been unclear. Mlh1-Mlh2 formed foci that often colocalized with and had a longer lifetime than Mlh1-Pms1 foci. Mlh1-Mlh2 foci were similar to Mlh1-Pms1 foci: they required mispair recognition by Msh2-Msh6, increased in response to increased mispairs or downstream defects in MMR, and formed after induction of DNA damage by phleomycin but not double-stranded breaks by I-SceI. Mlh1-Mlh2 could be recruited to mispair-containing DNA in vitro by either Msh2-Msh6 or Msh2-Msh3. Deletion of MLH2 caused a synergistic increase in mutation rate in combination with deletion of MSH6 or reduced expression of Pms1. Phylogenetic analysis demonstrated that the S. cerevisiae Mlh2 protein and the mammalian PMS1 protein are homologs. These results support a hypothesis that Mlh1-Mlh2 is a non-essential accessory factor that acts to enhance the activity of Mlh1-Pms1.

A massive parallel sequencing workflow for diagnostic genetic testing of mismatch repair genes

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Hansen, Maren F; Neckmann, Ulrike; Lavik, Liss A S; Vold, Trine; Gilde, Bodil; Toft, Ragnhild K; Sjursen, Wenche

2014-01-01

The purpose of this study was to develop a massive parallel sequencing (MPS) workflow for diagnostic analysis of mismatch repair (MMR) genes using the GS Junior system (Roche). A pathogenic variant in one of four MMR genes, (MLH1, PMS2, MSH6, and MSH2), is the cause of Lynch Syndrome (LS), which mainly predispose to colorectal cancer. We used an amplicon-based sequencing method allowing specific and preferential amplification of the MMR genes including PMS2, of which several pseudogenes exist. The amplicons were pooled at different ratios to obtain coverage uniformity and maximize the throughput of a single-GS Junior run. In total, 60 previously identified and distinct variants (substitutions and indels), were sequenced by MPS and successfully detected. The heterozygote detection range was from 19% to 63% and dependent on sequence context and coverage. We were able to distinguish between false-positive and true-positive calls in homopolymeric regions by cross-sample comparison and evaluation of flow signal distributions. In addition, we filtered variants according to a predefined status, which facilitated variant annotation. Our study shows that implementation of MPS in routine diagnostics of LS can accelerate sample throughput and reduce costs without compromising sensitivity, compared to Sanger sequencing. PMID:24689082

Activation of Saccharomyces cerevisiae Mlh1-Pms1 Endonuclease in a Reconstituted Mismatch Repair System*

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Smith, Catherine E.; Bowen, Nikki; Graham, William J.; Goellner, Eva M.; Srivatsan, Anjana; Kolodner, Richard D.

2015-01-01

Previous studies reported the reconstitution of an Mlh1-Pms1-independent 5′ nick-directed mismatch repair (MMR) reaction using Saccharomyces cerevisiae proteins. Here we describe the reconstitution of a mispair-dependent Mlh1-Pms1 endonuclease activation reaction requiring Msh2-Msh6 (or Msh2-Msh3), proliferating cell nuclear antigen (PCNA), and replication factor C (RFC) and a reconstituted Mlh1-Pms1-dependent 3′ nick-directed MMR reaction requiring Msh2-Msh6 (or Msh2-Msh3), exonuclease 1 (Exo1), replication protein A (RPA), RFC, PCNA, and DNA polymerase δ. Both reactions required Mg2+ and Mn2+ for optimal activity. The MMR reaction also required two reaction stages in which the first stage required incubation of Mlh1-Pms1 with substrate DNA, with or without Msh2-Msh6 (or Msh2-Msh3), PCNA, and RFC but did not require nicking of the substrate, followed by a second stage in which other proteins were added. Analysis of different mutant proteins demonstrated that both reactions required a functional Mlh1-Pms1 endonuclease active site, as well as mispair recognition and Mlh1-Pms1 recruitment by Msh2-Msh6 but not sliding clamp formation. Mutant Mlh1-Pms1 and PCNA proteins that were defective for Exo1-independent but not Exo1-dependent MMR in vivo were partially defective in the Mlh1-Pms1 endonuclease and MMR reactions, suggesting that both reactions reflect the activation of Mlh1-Pms1 seen in Exo1-independent MMR in vivo. The availability of this reconstituted MMR reaction should now make it possible to better study both Exo1-independent and Exo1-dependent MMR. PMID:26170454

Activation of Saccharomyces cerevisiae Mlh1-Pms1 Endonuclease in a Reconstituted Mismatch Repair System.

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Smith, Catherine E; Bowen, Nikki; Graham, William J; Goellner, Eva M; Srivatsan, Anjana; Kolodner, Richard D

2015-08-28

Previous studies reported the reconstitution of an Mlh1-Pms1-independent 5' nick-directed mismatch repair (MMR) reaction using Saccharomyces cerevisiae proteins. Here we describe the reconstitution of a mispair-dependent Mlh1-Pms1 endonuclease activation reaction requiring Msh2-Msh6 (or Msh2-Msh3), proliferating cell nuclear antigen (PCNA), and replication factor C (RFC) and a reconstituted Mlh1-Pms1-dependent 3' nick-directed MMR reaction requiring Msh2-Msh6 (or Msh2-Msh3), exonuclease 1 (Exo1), replication protein A (RPA), RFC, PCNA, and DNA polymerase δ. Both reactions required Mg(2+) and Mn(2+) for optimal activity. The MMR reaction also required two reaction stages in which the first stage required incubation of Mlh1-Pms1 with substrate DNA, with or without Msh2-Msh6 (or Msh2-Msh3), PCNA, and RFC but did not require nicking of the substrate, followed by a second stage in which other proteins were added. Analysis of different mutant proteins demonstrated that both reactions required a functional Mlh1-Pms1 endonuclease active site, as well as mispair recognition and Mlh1-Pms1 recruitment by Msh2-Msh6 but not sliding clamp formation. Mutant Mlh1-Pms1 and PCNA proteins that were defective for Exo1-independent but not Exo1-dependent MMR in vivo were partially defective in the Mlh1-Pms1 endonuclease and MMR reactions, suggesting that both reactions reflect the activation of Mlh1-Pms1 seen in Exo1-independent MMR in vivo. The availability of this reconstituted MMR reaction should now make it possible to better study both Exo1-independent and Exo1-dependent MMR. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

DNA mismatch repair gene MLH1 induces apoptosis in prostate cancer cells.

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Fukuhara, Shinichiro; Chang, Inik; Mitsui, Yozo; Chiyomaru, Takeshi; Yamamura, Soichiro; Majid, Shahana; Saini, Sharanjot; Hirata, Hiroshi; Deng, Guoren; Gill, Ankurpreet; Wong, Darryn K; Shiina, Hiroaki; Nonomura, Norio; Dahiya, Rajvir; Tanaka, Yuichiro

2014-11-30

Mismatch repair (MMR) enzymes have been shown to be deficient in prostate cancer (PCa). MMR can influence the regulation of tumor development in various cancers but their role on PCa has not been investigated. The aim of the present study was to determine the functional effects of the mutL-homolog 1 (MLH1) gene on growth of PCa cells. The DU145 cell line has been established as MLH1-deficient and thus, this cell line was utilized to determine effects of MLH1 by gene expression. Lack of MLH1 protein expression was confirmed by Western blotting in DU145 cells whereas levels were high in normal PWR-1E and RWPE-1 prostatic cells. MLH1-expressing stable transfectant DU145 cells were then created to characterize the effects this MMR gene has on various growth properties. Expression of MLH1 resulted in decreased cell proliferation, migration and invasion properties. Lack of cell growth in vivo also indicated a tumor suppressive effect by MLH1. Interestingly, MLH1 caused an increase in apoptosis along with phosphorylated c-Abl, and treatment with MLH1 siRNAs countered this effect. Furthermore, inhibition of c-Abl with STI571 also abrogated the effect on apoptosis caused by MLH1. These results demonstrate MLH1 protects against PCa development by inducing c-Abl-mediated apoptosis.

Calibration of Multiple In Silico Tools for Predicting Pathogenicity of Mismatch Repair Gene Missense Substitutions

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Thompson, Bryony A.; Greenblatt, Marc S.; Vallee, Maxime P.; Herkert, Johanna C.; Tessereau, Chloe; Young, Erin L.; Adzhubey, Ivan A.; Li, Biao; Bell, Russell; Feng, Bingjian; Mooney, Sean D.; Radivojac, Predrag; Sunyaev, Shamil R.; Frebourg, Thierry; Hofstra, Robert M.W.; Sijmons, Rolf H.; Boucher, Ken; Thomas, Alun; Goldgar, David E.; Spurdle, Amanda B.; Tavtigian, Sean V.

2015-01-01

Classification of rare missense substitutions observed during genetic testing for patient management is a considerable problem in clinical genetics. The Bayesian integrated evaluation of unclassified variants is a solution originally developed for BRCA1/2. Here, we take a step toward an analogous system for the mismatch repair (MMR) genes (MLH1, MSH2, MSH6, and PMS2) that confer colon cancer susceptibility in Lynch syndrome by calibrating in silico tools to estimate prior probabilities of pathogenicity for MMR gene missense substitutions. A qualitative five-class classification system was developed and applied to 143 MMR missense variants. This identified 74 missense substitutions suitable for calibration. These substitutions were scored using six different in silico tools (Align-Grantham Variation Grantham Deviation, multivariate analysis of protein polymorphisms [MAPP], Mut-Pred, PolyPhen-2.1, Sorting Intolerant From Tolerant, and Xvar), using curated MMR multiple sequence alignments where possible. The output from each tool was calibrated by regression against the classifications of the 74 missense substitutions; these calibrated outputs are interpretable as prior probabilities of pathogenicity. MAPP was the most accurate tool and MAPP + PolyPhen-2.1 provided the best-combined model (R2 = 0.62 and area under receiver operating characteristic = 0.93). The MAPP + PolyPhen-2.1 output is sufficiently predictive to feed as a continuous variable into the quantitative Bayesian integrated evaluation for clinical classification of MMR gene missense substitutions. PMID:22949387

Replication Stalling and Heteroduplex Formation within CAG/CTG Trinucleotide Repeats by Mismatch Repair

KAUST Repository

Viterbo, David; Michoud, Gregoire; Mosbach, Valentine; Dujon, Bernard; Richard, Guy-Franck

2016-01-01

Trinucleotide repeat expansions are responsible for at least two dozen neurological disorders. Mechanisms leading to these large expansions of repeated DNA are still poorly understood. It was proposed that transient stalling of the replication fork by the repeat tract might trigger slippage of the newly-synthesized strand over its template, leading to expansions or contractions of the triplet repeat. However, such mechanism was never formally proven. Here we show that replication fork pausing and CAG/CTG trinucleotide repeat instability are not linked, stable and unstable repeats exhibiting the same propensity to stall replication forks when integrated in a yeast natural chromosome. We found that replication fork stalling was dependent on the integrity of the mismatch-repair system, especially the Msh2p-Msh6p complex, suggesting that direct interaction of MMR proteins with secondary structures formed by trinucleotide repeats in vivo, triggers replication fork pauses. We also show by chromatin immunoprecipitation that Msh2p is enriched at trinucleotide repeat tracts, in both stable and unstable orientations, this enrichment being dependent on MSH3 and MSH6. Finally, we show that overexpressing MSH2 favors the formation of heteroduplex regions, leading to an increase in contractions and expansions of CAG/CTG repeat tracts during replication, these heteroduplexes being dependent on both MSH3 and MSH6. These heteroduplex regions were not detected when a mutant msh2-E768A gene in which the ATPase domain was mutated was overexpressed. Our results unravel two new roles for mismatch-repair proteins: stabilization of heteroduplex regions and transient blocking of replication forks passing through such repeats. Both roles may involve direct interactions between MMR proteins and secondary structures formed by trinucleotide repeat tracts, although indirect interactions may not be formally excluded.

Replication Stalling and Heteroduplex Formation within CAG/CTG Trinucleotide Repeats by Mismatch Repair

KAUST Repository

Viterbo, David

2016-03-16

Trinucleotide repeat expansions are responsible for at least two dozen neurological disorders. Mechanisms leading to these large expansions of repeated DNA are still poorly understood. It was proposed that transient stalling of the replication fork by the repeat tract might trigger slippage of the newly-synthesized strand over its template, leading to expansions or contractions of the triplet repeat. However, such mechanism was never formally proven. Here we show that replication fork pausing and CAG/CTG trinucleotide repeat instability are not linked, stable and unstable repeats exhibiting the same propensity to stall replication forks when integrated in a yeast natural chromosome. We found that replication fork stalling was dependent on the integrity of the mismatch-repair system, especially the Msh2p-Msh6p complex, suggesting that direct interaction of MMR proteins with secondary structures formed by trinucleotide repeats in vivo, triggers replication fork pauses. We also show by chromatin immunoprecipitation that Msh2p is enriched at trinucleotide repeat tracts, in both stable and unstable orientations, this enrichment being dependent on MSH3 and MSH6. Finally, we show that overexpressing MSH2 favors the formation of heteroduplex regions, leading to an increase in contractions and expansions of CAG/CTG repeat tracts during replication, these heteroduplexes being dependent on both MSH3 and MSH6. These heteroduplex regions were not detected when a mutant msh2-E768A gene in which the ATPase domain was mutated was overexpressed. Our results unravel two new roles for mismatch-repair proteins: stabilization of heteroduplex regions and transient blocking of replication forks passing through such repeats. Both roles may involve direct interactions between MMR proteins and secondary structures formed by trinucleotide repeat tracts, although indirect interactions may not be formally excluded.

Overexpression of the DNA mismatch repair factor, PMS2, confers hypermutability and DNA damage tolerance.

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Gibson, Shannon L; Narayanan, Latha; Hegan, Denise Campisi; Buermeyer, Andrew B; Liskay, R Michael; Glazer, Peter M

2006-12-08

Inherited defects in genes associated with DNA mismatch repair (MMR) have been linked to familial colorectal cancer. Cells deficient in MMR are genetically unstable and demonstrate a tolerance phenotype in response to certain classes of DNA damage. Some sporadic human cancers also show abnormalities in MMR gene function, typically due to diminished expression of one of the MutL homologs, MLH1. Here, we report that overexpression of the MutL homolog, human PMS2, can also cause a disruption of the MMR pathway in mammalian cells, resulting in hypermutability and DNA damage tolerance. A mouse fibroblast cell line carrying a recoverable lambda phage shuttle vector for mutation detection was transfected with either a vector designed to express hPMS2 or with an empty vector control. Cells overexpressing hPMS2 were found to have elevated spontaneous mutation frequencies at the cII reporter gene locus. They also showed an increase in the level of mutations induced by the alkylating agent, methynitrosourea (MNU). Clonogenic survival assays demonstrated increased survival of the PMS2-overexpressing cells following exposure to MNU, consistent with the induction of a damage tolerance phenotype. Similar results were seen in cells expressing a mutant PMS2 gene, containing a premature stop codon at position 134 and representing a variant found in an individual with familial colon cancer. These results show that dysregulation of PMS2 gene expression can disrupt MMR function in mammalian cells and establish an additional carcinogenic mechanism by which cells can develop genetic instability and acquire resistance to cytotoxic cancer therapies.

Clinical problems of colorectal cancer and endometrial cancer cases with unknown cause of tumor mismatch repair deficiency (suspected Lynch syndrome).

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Buchanan, Daniel D; Rosty, Christophe; Clendenning, Mark; Spurdle, Amanda B; Win, Aung Ko

2014-01-01

Carriers of a germline mutation in one of the DNA mismatch repair (MMR) genes have a high risk of developing numerous different cancers, predominantly colorectal cancer and endometrial cancer (known as Lynch syndrome). MMR gene mutation carriers develop tumors with MMR deficiency identified by tumor microsatellite instability or immunohistochemical loss of MMR protein expression. Tumor MMR deficiency is used to identify individuals most likely to carry an MMR gene mutation. However, MMR deficiency can also result from somatic inactivation, most commonly methylation of the MLH1 gene promoter. As tumor MMR testing of all incident colorectal and endometrial cancers (universal screening) is becoming increasingly adopted, a growing clinical problem is emerging for individuals who have tumors that show MMR deficiency who are subsequently found not to carry an MMR gene mutation after genetic testing using the current diagnostic approaches (Sanger sequencing and multiplex ligation-dependent probe amplification) and who also show no evidence of MLH1 methylation. The inability to determine the underlying cause of tumor MMR deficiency in these "Lynch-like" or "suspected Lynch syndrome" cases has significant implications on the clinical management of these individuals and their relatives. When the data from published studies are combined, 59% (95% confidence interval [CI]: 55% to 64%) of colorectal cancers and 52% (95% CI: 41% to 62%) of endometrial cancers with MMR deficiency were identified as suspected Lynch syndrome. Recent studies estimated that colorectal cancer risk for relatives of suspected Lynch syndrome cases is lower than for relatives of those with MMR gene mutations, but higher than for relatives of those with tumor MMR deficiency resulting from methylation of the MLH1 gene promoter. The cause of tumor MMR deficiency in suspected Lynch syndrome cases is likely due to either unidentified germline MMR gene mutations, somatic cell mosaicism, or biallelic somatic

Evaluating the performance of clinical criteria for predicting mismatch repair gene mutations in Lynch syndrome: a comprehensive analysis of 3,671 families.

Science.gov (United States)

Steinke, Verena; Holzapfel, Stefanie; Loeffler, Markus; Holinski-Feder, Elke; Morak, Monika; Schackert, Hans K; Görgens, Heike; Pox, Christian; Royer-Pokora, Brigitte; von Knebel-Doeberitz, Magnus; Büttner, Reinhard; Propping, Peter; Engel, Christoph

2014-07-01

Carriers of mismatch repair (MMR) gene mutations have a high lifetime risk for colorectal and endometrial cancers, as well as other malignancies. As mutation analysis to detect these patients is expensive and time-consuming, clinical criteria and tumor-tissue analysis are widely used as pre-screening methods. The aim of our study was to evaluate the performance of commonly applied clinical criteria (the Amsterdam I and II Criteria, and the original and revised Bethesda Guidelines) and the results of tumor-tissue analysis in predicting MMR gene mutations. We analyzed 3,671 families from the German HNPCC Registry and divided them into nine mutually exclusive groups with different clinical criteria. A total of 680 families (18.5%) were found to have a pathogenic MMR gene mutation. Among all 1,284 families with microsatellite instability-high (MSI-H) colorectal cancer, the overall mutation detection rate was 53.0%. Mutation frequencies and their distribution between the four MMR genes differed significantly between clinical groups (p small-bowel cancer (p small-bowel cancer were clinically relevant predictors for Lynch syndrome. © 2013 UICC.

Comparison of the Mismatch Repair System between Primary and Metastatic Colorectal Cancers Using Immunohistochemistry

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Jiyoon Jung

2017-03-01

Full Text Available Background Colorectal cancer (CRC is one of the most common malignancies worldwide. Approximately 10%–15% of the CRC cases have defective DNA mismatch repair (MMR genes. Although the high level of microsatellite instability status is a predictor of favorable outcome in primary CRC, little is known about its frequency and importance in secondary CRC. Immunohistochemical staining (IHC for MMR proteins (e.g., MLH1, MSH2, MSH6, and PMS2 has emerged as a useful technique to complement polymerase chain reaction (PCR analyses. Methods In this study, comparison between the MMR system of primary CRCs and paired liver and lung metastatic lesions was done using IHC and the correlation with clinical outcomes was also examined. Results Based on IHC, 7/61 primary tumors (11.4% showed deficient MMR systems, while 13/61 secondary tumors (21.3% showed deficiencies. In total, 44 cases showed proficient expression in both the primary and metastatic lesions. Three cases showed deficiencies in both the primary and paired metastatic lesions. In 10 cases, proficient expression was found only in the primary lesions, and not in the corresponding metastatic lesions. In four cases, proficient expression was detected in the secondary tumor, but not in the primary tumor. Conclusions Although each IHC result and the likely defective genes were not exactly matched between the primary and the metastatic tumors, identical results for primary and metastatic lesions were obtained in 77% of the cases (47/61. These data are in agreement with the previous microsatellite detection studies that used PCR and IHC.

Genome-wide analysis of heteroduplex DNA in mismatch repair-deficient yeast cells reveals novel properties of meiotic recombination pathways.

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Emmanuelle Martini

2011-09-01

Full Text Available Meiotic DNA double-strand breaks (DSBs initiate crossover (CO recombination, which is necessary for accurate chromosome segregation, but DSBs may also repair as non-crossovers (NCOs. Multiple recombination pathways with specific intermediates are expected to lead to COs and NCOs. We revisited the mechanisms of meiotic DSB repair and the regulation of CO formation, by conducting a genome-wide analysis of strand-transfer intermediates associated with recombination events. We performed this analysis in a SK1 × S288C Saccharomyces cerevisiae hybrid lacking the mismatch repair (MMR protein Msh2, to allow efficient detection of heteroduplex DNAs (hDNAs. First, we observed that the anti-recombinogenic activity of MMR is responsible for a 20% drop in CO number, suggesting that in MMR-proficient cells some DSBs are repaired using the sister chromatid as a template when polymorphisms are present. Second, we observed that a large fraction of NCOs were associated with trans-hDNA tracts constrained to a single chromatid. This unexpected finding is compatible with dissolution of double Holliday junctions (dHJs during repair, and it suggests the existence of a novel control point for CO formation at the level of the dHJ intermediate, in addition to the previously described control point before the dHJ formation step. Finally, we observed that COs are associated with complex hDNA patterns, confirming that the canonical double-strand break repair model is not sufficient to explain the formation of most COs. We propose that multiple factors contribute to the complexity of recombination intermediates. These factors include repair of nicks and double-stranded gaps, template switches between non-sister and sister chromatids, and HJ branch migration. Finally, the good correlation between the strand transfer properties observed in the absence of and in the presence of Msh2 suggests that the intermediates detected in the absence of Msh2 reflect normal intermediates.

Peritumoral granulomatous reaction in endometrial carcinoma: association with DNA mismatch repair protein deficiency, particularly loss of PMS2 expression.

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Stewart, Colin J R; Pearn, Amy; Pachter, Nicholas; Tan, Adeline

2018-04-30

The observation of peritumoral granulomatous reactions (PGRs) in two endometrial carcinomas (ECs) with a PMS2-deficient/MLH1-intact expression pattern led us to investigate whether PGRs in EC were specifically associated with DNA mismatch repair (MMR) protein deficiency, particularly PMS2 loss. Hysterectomy specimens from 22 MMR protein-intact and 54 MMR protein-deficient ECs were reviewed with specific attention to the presence of a PGR and a tumour-associated lymphoid reaction [including tumour-infiltrating lymphocytes (TILs) and stromal lymphoid infiltrates]. The MMR protein-deficient ECs included 22 cases with combined MLH1/PMS2 loss, 11 with combined MSH2/MSH6 loss, 11 with isolated MSH6 loss, and 10 with PMS2 loss but intact MLH1 staining (including the two 'index' cases). Overall, PGRs were identified in seven of 54 (13%) MMR protein-deficient ECs, five of which showed a PMS2-deficient/MLH1-intact immunophenotype; three of these patients had germline PMS2 mutations and one additional patient had a germline MSH6 mutation. None of the MMR protein-intact tumours showed a PGR. Although five of the seven PGR-positive ECs had a high-grade histological component, six were stage I. Most ECs with PGRs also showed TILs and stromal lymphoid reactions, similarly to MMR protein-deficient ECs in general. MMR protein-deficient ECs, particularly those with PMS2 loss, occasionally show PGRs in addition to stromal lymphoid infiltrates and TILs. Therefore, PGRs could be considered to constitute a histological prompt for consideration of Lynch syndrome. The potential prognostic significance of PGRs in EC requires further study. © 2018 John Wiley & Sons Ltd.

DNA Mismatch Repair Deficiency in Rectal Cancer: Benchmarking Its Impact on Prognosis, Neoadjuvant Response Prediction, and Clinical Cancer Genetics.

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de Rosa, Nicole; Rodriguez-Bigas, Miguel A; Chang, George J; Veerapong, Jula; Borras, Ester; Krishnan, Sunil; Bednarski, Brian; Messick, Craig A; Skibber, John M; Feig, Barry W; Lynch, Patrick M; Vilar, Eduardo; You, Y Nancy

2016-09-01

DNA mismatch repair deficiency (dMMR) hallmarks consensus molecular subtype 1 of colorectal cancer. It is being routinely tested, but little is known about dMMR rectal cancers. The efficacy of novel treatment strategies cannot be established without benchmarking the outcomes of dMMR rectal cancer with current therapy. We aimed to delineate the impact of dMMR on prognosis, the predicted response to fluoropyrimidine-based neoadjuvant therapy, and implications of germline alterations in the MMR genes in rectal cancer. Between 1992 and 2012, 62 patients with dMMR rectal cancers underwent multimodality therapy. Oncologic treatment and outcomes as well as clinical genetics work-up were examined. Overall and rectal cancer-specific survival were calculated by the Kaplan-Meier method. The median age at diagnosis was 41 years. MMR deficiency was most commonly due to alterations in MSH2 (53%) or MSH6 (23%). After a median follow-up of 6.8 years, the 5-year rectal cancer-specific survival was 100% for stage I and II, 85.1% for stage III, and 60.0% for stage IV disease. Fluoropyrimidine-based neoadjuvant chemoradiation was associated with a complete pathologic response rate of 27.6%. The extent of surgical resection was influenced by synchronous colonic disease at presentation, tumor height, clinical stage, and pelvic radiation. An informed decision for a limited resection focusing on proctectomy did not compromise overall survival. Five of the 11 (45.5%) deaths during follow-up were due to extracolorectal malignancies. dMMR rectal cancer had excellent prognosis and pathologic response with current multimodality therapy including an individualized surgical treatment plan. Identification of a dMMR rectal cancer should trigger germline testing, followed by lifelong surveillance for both colorectal and extracolorectal malignancies. We herein provide genotype-specific outcome benchmarks for comparison with novel interventions. © 2016 by American Society of Clinical Oncology.

Establishment, characterization and chemosensitivity of three mismatch repair deficient cell lines from sporadic and inherited colorectal carcinomas.

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Claudia Maletzki

Full Text Available BACKGROUND: Colorectal cancer (CRC represents a morphologic and molecular heterogenic disease. This heterogeneity substantially impairs drug effectiveness and prognosis. The subtype of mismatch repair deficient (MMR-D CRCs, accounting for about 15% of all cases, shows particular differential responses up to resistance towards currently approved cytostatic drugs. Pre-clinical in vitro models representing molecular features of MMR-D tumors are thus mandatory for identifying biomarkers that finally help to predict responses towards new cytostatic drugs. Here, we describe the successful establishment and characterization of three patient-derived MMR-D cell lines (HROC24, HROC87, and HROC113 along with their corresponding xenografts. METHODOLOGY: MMR-D cell lines (HROC24, HROC87, and HROC113 were established from a total of ten clinicopathological well-defined MMR-D cases (120 CRC cases in total. Cells were comprehensively characterized by phenotype, morphology, growth kinetics, invasiveness, and molecular profile. Additionally, response to clinically relevant chemotherapeutics was examined in vitro and in vivo. PRINCIPAL FINDINGS: Two MMR-D lines showing CIMP-H derived from sporadic CRC (HROC24: K-ras(wt, B-raf(mut, HROC87: K-ras(wt, B-raf(mut, whereas the HROC113 cell line (K-ras(mut, B-raf(wt was HNPCC-associated. A diploid DNA-status could be verified by flow cytometry and SNP Array analysis. All cell lines were characterized as epithelial (EpCAM(+ tumor cells, showing surface tumor marker expression (CEACAM(+. MHC-class II was inducible by Interferon-γ stimulation. Growth kinetics as well as invasive potential was quite heterogeneous between individual lines. Besides, MMR-D cell lines exhibited distinct responsiveness towards chemotherapeutics, even when comparing in vitro and in vivo sensitivity. CONCLUSIONS: These newly established and well-characterized, low-passage MMR-D cell lines provide a useful tool for future investigations on the

Connections between constitutional mismatch repair deficiency syndrome and neurofibromatosis type 1.

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Wimmer, K; Rosenbaum, T; Messiaen, L

2017-04-01

Constitutional mismatch repair (MMR) deficiency (CMMRD) is a rare childhood cancer susceptibility syndrome resulting from biallelic germline loss-of-function mutations in one of the MMR genes. Individuals with CMMRD have high risk to develop a broad spectrum of malignancies and frequently display features reminiscent of neurofibromatosis type 1 (NF1). Evaluation of the clinical findings of genetically proven CMMRD patients shows that not only multiple café-au-lait macules but also any of the diagnostic features of NF1 may be present in a CMMRD patient. This phenotypic overlap may lead to misdiagnosis of CMMRD patients as having NF1, which impedes adequate management of the patients and their families. The spectrum of CMMRD-associated childhood malignancies includes high-grade glioma, acute myeloid leukaemia or rhabdomyosarcoma, also reported as associated with NF1. Reported associations between NF1 and these malignancies are to a large extent based on studies that neither proved the presence of an NF1 germline mutation nor ruled-out CMMRD in the affected. Hence, these associations are challenged by our current knowledge of the phenotypic overlap between NF1 and CMMRD and should be re-evaluated in future studies. Recent advances in the diagnostics of CMMRD should render it possible to definitely state or refute this diagnosis in these individuals. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Higher occurrence of childhood cancer in families with germline mutations in BRCA2, MMR and CDKN2A genes

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Magnusson, S.; Borg, A.; Kristoffersson, U.

2008-01-01

The contribution of hereditary factors for development of childhood tumors is limited to some few known syndromes associated with predominance of tumors in childhood. Occurrence of childhood tumors in hereditary cancer syndromes such as BRCA1/2 associated breast and ovarian cancer, DNA-mismatch r......-mismatch repair (MMR) genes associated hereditary non polyposis colorectal cancer and CDKN2A associated familial malignant melanoma are very little studied. Herein we report the prevalence of childhood tumors (diagnosed...

Systematic immunohistochemical screening for mismatch repair and ERCC1 gene expression from colorectal cancers in China: Clinicopathological characteristics and effects on survival.

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Pan Li

Full Text Available We performed a systematic screening of colorectal cancer (CRC tissues to investigate whether mismatch repair (MMR status and ERCC1 protein expression could be predictive of clinical outcomes for these patients following the recommendation of The Evaluation of Genomic Applications in Practice of Prevention (EGAPP.The expression of four MMR genes and ERCC1 were assessed by immunohistochemistry (IHC from cancer tissue samples of 2233 consecutive CRC patients.We observed that most CRC patients with a proficient MMR (pMMR status tended to have simultaneous ERCC1 protein expression (P< 0.001. Stage III CRC patients with deficient MMR (dMMR had higher prognoses than the same stage patients with pMMR (DFS: 74% vs 65%, P = 0.04; OS: 79% vs 69%, P = 0.04. Here, dMMR is also associated with poorer survival for stage II patients after chemotherapy (DFS: 66% vs 78%, P = 0.04. Stage II and III patients that were shown to express ERCC1 protein had higher DFS and OS than those that were deficient in expression (stage II, DFS: 83% vs 70%, P = 0.006; OS 85% vs 73%, P = 0.02. Stage III, DFS: 67% vs56%, P = 0.03; OS: 71% vs 57%, P = 0.04.Our results indicate that dMMR appeared to predictive of a survival benefit for stage III CRC patients. We also found the determination of ERCC1 expression to be useful for predicting DFS or OS for stage II and III CRC patients. In addition, the expression of MMR genes and ERCC1 showed a significant relationship.

Mismatch repair genes Mlh1 and Mlh3 modify CAG instability in Huntington's disease mice: genome-wide and candidate approaches.

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Pinto, Ricardo Mouro; Dragileva, Ella; Kirby, Andrew; Lloret, Alejandro; Lopez, Edith; St Claire, Jason; Panigrahi, Gagan B; Hou, Caixia; Holloway, Kim; Gillis, Tammy; Guide, Jolene R; Cohen, Paula E; Li, Guo-Min; Pearson, Christopher E; Daly, Mark J; Wheeler, Vanessa C

2013-10-01

The Huntington's disease gene (HTT) CAG repeat mutation undergoes somatic expansion that correlates with pathogenesis. Modifiers of somatic expansion may therefore provide routes for therapies targeting the underlying mutation, an approach that is likely applicable to other trinucleotide repeat diseases. Huntington's disease Hdh(Q111) mice exhibit higher levels of somatic HTT CAG expansion on a C57BL/6 genetic background (B6.Hdh(Q111) ) than on a 129 background (129.Hdh(Q111) ). Linkage mapping in (B6x129).Hdh(Q111) F2 intercross animals identified a single quantitative trait locus underlying the strain-specific difference in expansion in the striatum, implicating mismatch repair (MMR) gene Mlh1 as the most likely candidate modifier. Crossing B6.Hdh(Q111) mice onto an Mlh1 null background demonstrated that Mlh1 is essential for somatic CAG expansions and that it is an enhancer of nuclear huntingtin accumulation in striatal neurons. Hdh(Q111) somatic expansion was also abolished in mice deficient in the Mlh3 gene, implicating MutLγ (MLH1-MLH3) complex as a key driver of somatic expansion. Strikingly, Mlh1 and Mlh3 genes encoding MMR effector proteins were as critical to somatic expansion as Msh2 and Msh3 genes encoding DNA mismatch recognition complex MutSβ (MSH2-MSH3). The Mlh1 locus is highly polymorphic between B6 and 129 strains. While we were unable to detect any difference in base-base mismatch or short slipped-repeat repair activity between B6 and 129 MLH1 variants, repair efficiency was MLH1 dose-dependent. MLH1 mRNA and protein levels were significantly decreased in 129 mice compared to B6 mice, consistent with a dose-sensitive MLH1-dependent DNA repair mechanism underlying the somatic expansion difference between these strains. Together, these data identify Mlh1 and Mlh3 as novel critical genetic modifiers of HTT CAG instability, point to Mlh1 genetic variation as the likely source of the instability difference in B6 and 129 strains and suggest that MLH1

Mismatch repair genes Mlh1 and Mlh3 modify CAG instability in Huntington's disease mice: genome-wide and candidate approaches.

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Ricardo Mouro Pinto

2013-10-01

Full Text Available The Huntington's disease gene (HTT CAG repeat mutation undergoes somatic expansion that correlates with pathogenesis. Modifiers of somatic expansion may therefore provide routes for therapies targeting the underlying mutation, an approach that is likely applicable to other trinucleotide repeat diseases. Huntington's disease Hdh(Q111 mice exhibit higher levels of somatic HTT CAG expansion on a C57BL/6 genetic background (B6.Hdh(Q111 than on a 129 background (129.Hdh(Q111 . Linkage mapping in (B6x129.Hdh(Q111 F2 intercross animals identified a single quantitative trait locus underlying the strain-specific difference in expansion in the striatum, implicating mismatch repair (MMR gene Mlh1 as the most likely candidate modifier. Crossing B6.Hdh(Q111 mice onto an Mlh1 null background demonstrated that Mlh1 is essential for somatic CAG expansions and that it is an enhancer of nuclear huntingtin accumulation in striatal neurons. Hdh(Q111 somatic expansion was also abolished in mice deficient in the Mlh3 gene, implicating MutLγ (MLH1-MLH3 complex as a key driver of somatic expansion. Strikingly, Mlh1 and Mlh3 genes encoding MMR effector proteins were as critical to somatic expansion as Msh2 and Msh3 genes encoding DNA mismatch recognition complex MutSβ (MSH2-MSH3. The Mlh1 locus is highly polymorphic between B6 and 129 strains. While we were unable to detect any difference in base-base mismatch or short slipped-repeat repair activity between B6 and 129 MLH1 variants, repair efficiency was MLH1 dose-dependent. MLH1 mRNA and protein levels were significantly decreased in 129 mice compared to B6 mice, consistent with a dose-sensitive MLH1-dependent DNA repair mechanism underlying the somatic expansion difference between these strains. Together, these data identify Mlh1 and Mlh3 as novel critical genetic modifiers of HTT CAG instability, point to Mlh1 genetic variation as the likely source of the instability difference in B6 and 129 strains and suggest

Immunohistochemical null-phenotype for mismatch repair proteins in colonic carcinoma associated with concurrent MLH1 hypermethylation and MSH2 somatic mutations.

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Wang, Tao; Stadler, Zsofia K; Zhang, Liying; Weiser, Martin R; Basturk, Olca; Hechtman, Jaclyn F; Vakiani, Efsevia; Saltz, Lenard B; Klimstra, David S; Shia, Jinru

2018-04-01

Microsatellite instability, a well-established driver pathway in colorectal carcinogenesis, can develop in both sporadic and hereditary conditions via different molecular alterations in the DNA mismatch repair (MMR) genes. MMR protein immunohistochemistry (IHC) is currently widely used for the detection of MMR deficiency in solid tumors. The IHC test, however, can show varied staining patterns, posing challenges in the interpretation of the staining results in some cases. Here we report a case of an 80-year-old female with a colonic adenocarcinoma that exhibited an unusual "null" IHC staining pattern with complete loss of all four MMR proteins (MLH1, MSH2, MSH6, and PMS2). This led to subsequent MLH1 methylation testing and next generation sequencing which demonstrated that the loss of all MMR proteins was associated with concurrent promoter hypermethylation of MLH1 and double somatic truncating mutations in MSH2. These molecular findings, in conjunction with the patient's age being 80 years and the fact that the patient had no personal or family cancer history, indicated that the MMR deficiency was highly likely sporadic in nature. Thus, the stringent Lynch syndrome type surveillance programs were not recommended to the patient and her family members. This case illustrates a rare but important scenario where a null IHC phenotype signifies complex underlying molecular alternations that bear clinical management implications, highlighting the need for recognition and awareness of such unusual IHC staining patterns.

NPM-ALK mediates phosphorylation of MSH2 at tyrosine 238, creating a functional deficiency in MSH2 and the loss of mismatch repair

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Bone, K M; Wang, P; Wu, F; Wu, C; Li, L; Bacani, J T; Andrew, S E; Lai, R

2015-01-01

The vast majority of anaplastic lymphoma kinase-positive anaplastic large cell lymphoma (ALK+ALCL) tumors express the characteristic oncogenic fusion protein NPM-ALK, which mediates tumorigenesis by exerting its constitutive tyrosine kinase activity on various substrates. We recently identified MSH2, a protein central to DNA mismatch repair (MMR), as a novel binding partner and phosphorylation substrate of NPM-ALK. Here, using liquid chromatography–mass spectrometry, we report for the first time that MSH2 is phosphorylated by NPM-ALK at a specific residue, tyrosine 238. Using GP293 cells transfected with NPM-ALK, we confirmed that the MSH2 Y238F mutant is not tyrosine phosphorylated. Furthermore, transfection of MSH2 Y238F into these cells substantially decreased the tyrosine phosphorylation of endogenous MSH2. Importantly, gene transfection of MSH2 Y238F abrogated the binding of NPM-ALK with endogenous MSH2, re-established the dimerization of MSH2:MSH6 and restored the sensitivity to DNA mismatch-inducing drugs, indicative of MMR return. Parallel findings were observed in two ALK+ALCL cell lines, Karpas 299 and SUP-M2. In addition, we found that enforced expression of MSH2 Y238F into ALK+ALCL cells alone was sufficient to induce spontaneous apoptosis. In conclusion, our findings have identified NPM-ALK-induced phosphorylation of MSH2 at Y238 as a crucial event in suppressing MMR. Our studies have provided novel insights into the mechanism by which oncogenic tyrosine kinases disrupt MMR

Diagnosis of Constitutional Mismatch Repair-Deficiency Syndrome Based on Microsatellite Instability and Lymphocyte Tolerance to Methylating Agents.

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Bodo, Sahra; Colas, Chrystelle; Buhard, Olivier; Collura, Ada; Tinat, Julie; Lavoine, Noémie; Guilloux, Agathe; Chalastanis, Alexandra; Lafitte, Philippe; Coulet, Florence; Buisine, Marie-Pierre; Ilencikova, Denisa; Ruiz-Ponte, Clara; Kinzel, Miriam; Grandjouan, Sophie; Brems, Hilde; Lejeune, Sophie; Blanché, Hélène; Wang, Qing; Caron, Olivier; Cabaret, Odile; Svrcek, Magali; Vidaud, Dominique; Parfait, Béatrice; Verloes, Alain; Knappe, Ulrich J; Soubrier, Florent; Mortemousque, Isabelle; Leis, Alexander; Auclair-Perrossier, Jessie; Frébourg, Thierry; Fléjou, Jean-François; Entz-Werle, Natacha; Leclerc, Julie; Malka, David; Cohen-Haguenauer, Odile; Goldberg, Yael; Gerdes, Anne-Marie; Fedhila, Faten; Mathieu-Dramard, Michèle; Hamelin, Richard; Wafaa, Badre; Gauthier-Villars, Marion; Bourdeaut, Franck; Sheridan, Eamonn; Vasen, Hans; Brugières, Laurence; Wimmer, Katharina; Muleris, Martine; Duval, Alex

2015-10-01

Patients with bi-allelic germline mutations in mismatch repair (MMR) genes (MLH1, MSH2, MSH6, or PMS2) develop a rare but severe variant of Lynch syndrome called constitutional MMR deficiency (CMMRD). This syndrome is characterized by early-onset colorectal cancers, lymphomas or leukemias, and brain tumors. There is no satisfactory method for diagnosis of CMMRD because screens for mutations in MMR genes are noninformative for 30% of patients. MMR-deficient cancer cells are resistant to genotoxic agents and have microsatellite instability (MSI), due to accumulation of errors in repetitive DNA sequences. We investigated whether these features could be used to identify patients with CMMRD. We examined MSI by PCR analysis and tolerance to methylating or thiopurine agents (functional characteristics of MMR-deficient tumor cells) in lymphoblastoid cells (LCs) from 3 patients with CMMRD and 5 individuals with MMR-proficient LCs (controls). Using these assays, we defined experimental parameters that allowed discrimination of a series of 14 patients with CMMRD from 52 controls (training set). We then used the same parameters to assess 23 patients with clinical but not genetic features of CMMRD. In the training set, we identified parameters, based on MSI and LC tolerance to methylation, that detected patients with CMMRD vs controls with 100% sensitivity and 100% specificity. Among 23 patients suspected of having CMMRD, 6 had MSI and LC tolerance to methylation (CMMRD highly probable), 15 had neither MSI nor LC tolerance to methylation (unlikely to have CMMRD), and 2 were considered doubtful for CMMRD based on having only 1 of the 2 features. The presence of MSI and tolerance to methylation in LCs identified patients with CMMRD with 100% sensitivity and specificity. These features could be used in diagnosis of patients. Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.

An optimized pentaplex PCR for detecting DNA mismatch repair-deficient colorectal cancers.

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Ajay Goel

2010-02-01

Full Text Available Microsatellite instability (MSI is used to screen colorectal cancers (CRC for Lynch Syndrome, and to predict outcome and response to treatment. The current technique for measuring MSI requires DNA from normal and neoplastic tissues, and fails to identify tumors with specific DNA mismatch repair (MMR defects. We tested a panel of five quasi-monomorphic mononucleotide repeat markers amplified in a single multiplex PCR reaction (pentaplex PCR to detect MSI.We investigated a cohort of 213 CRC patients, comprised of 114 MMR-deficient and 99 MMR-proficient tumors. Immunohistochemical (IHC analysis evaluated the expression of MLH1, MSH2, PMS2 and MSH6. MSI status was defined by differences in the quasi-monomorphic variation range (QMVR from a pool of normal DNA samples, and measuring differences in allele lengths in tumor DNA.Amplification of 426 normal alleles allowed optimization of the QMVR at each marker, and eliminated the requirement for matched reference DNA to define MSI in each sample. Using > or = 2/5 unstable markers as the criteria for MSI resulted in a sensitivity of 95.6% (95% CI = 90.1-98.1% and a positive predictive value of 100% (95% CI = 96.6%-100%. Detection of MSH6-deficiency was limited using all techniques. Data analysis with a three-marker panel (BAT26, NR21 and NR27 was comparable in sensitivity (97.4% and positive predictive value (96.5% to the five marker panel. Both approaches were superior to the standard approach to measuring MSI.An optimized pentaplex (or triplex PCR offers a facile, robust, very inexpensive, highly sensitive, and specific assay for the identification of MSI in CRC.

Involvement of the DNA mismatch repair system in cisplatin sensitivity of testicular germ cell tumours.

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Rudolph, Christiane; Melau, Cecilie; Nielsen, John E; Vile Jensen, Kristina; Liu, Dekang; Pena-Diaz, Javier; Rajpert-De Meyts, Ewa; Rasmussen, Lene Juel; Jørgensen, Anne

2017-08-01

Testicular germ cell tumours (TGCT) are highly sensitive to cisplatin-based chemotherapy, but patients with tumours containing differentiated teratoma components are less responsive to this treatment. The cisplatin sensitivity in TGCT has previously been linked to the embryonic phenotype in the majority of tumours, although the underlying mechanism largely remains to be elucidated. The aim of this study was to investigate the role of the DNA mismatch repair (MMR) system in the cisplatin sensitivity of TGCT. The expression pattern of key MMR proteins, including MSH2, MSH6, MLH1 and PMS2, were investigated during testis development and in the pathogenesis of TGCT, including germ cell neoplasia in situ (GCNIS). The TGCT-derived cell line NTera2 was differentiated using retinoic acid (10 μM, 6 days) after which MMR protein expression and activity, as well as cisplatin sensitivity, were investigated in both undifferentiated and differentiated cells. Finally, the expression of MSH2 was knocked down by siRNA in NTera2 cells after which the effect on cisplatin sensitivity was examined. MMR proteins were expressed in proliferating cells in the testes, while in malignant germ cells MMR protein expression was found to coincide with the expression of the pluripotency factor OCT4, with no or low expression in the more differentiated yolk sac tumours, choriocarcinomas and teratomas. In differentiated NTera2 cells we found a significantly (p cisplatin sensitivity, compared to undifferentiated NTera2 cells. Also, we found that partial knockdown of MSH2 expression in undifferentiated NTera2 cells resulted in a significantly (p cisplatin sensitivity. This study reports, for the first time, expression of the MMR system in fetal gonocytes, from which GCNIS cells are derived. Our findings in primary TGCT specimens and TGCT-derived cells suggest that a reduced sensitivity to cisplatin in differentiated TGCT components could result from a reduced expression of MMR proteins, in

Crystal structure and DNA-binding property of the ATPase domain of bacterial mismatch repair endonuclease MutL from Aquifex aeolicus.

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Fukui, Kenji; Iino, Hitoshi; Baba, Seiki; Kumasaka, Takashi; Kuramitsu, Seiki; Yano, Takato

2017-09-01

DNA mismatch repair (MMR) system corrects mismatched bases that are generated mainly by DNA replication errors. The repair system excises the error-containing single-stranded region and enables the re-synthesis of the strand. In the early reactions of MMR, MutL endonuclease incises the newly-synthesized/error-containing strand of the duplex to initiate the downstream excision reaction. MutL endonuclease consists of the N-terminal ATPase and C-terminal endonuclease domains. In this study, we report the crystal structure of the ATPase domain of MutL endonuclease from Aquifex aeolicus. The overall structure of the domain was similar to those of human MutL homologs and Escherichia coli MutL, although E. coli MutL has no endonuclease activity. The ATPase domain was comprised of two subdomains: the N-terminal ATP-binding subdomain and the C-terminal α-β sandwich subdomain. Site-directed mutagenesis experiment identified DNA-interacting eight basic amino acid residues, which were distributed across both the two subdomains and formed a DNA-binding cleft. Docking simulation between the structures of the ATPase and endonuclease domains generated a reliable model structure for the full-length A. aeolicus MutL, which satisfies our previous result of small-angle X-ray scattering analysis. On the basis of the model structure and further experimental results, we concluded that the two separate DNA-binding sites in the full-length A. aeolicus MutL simultaneously bind a dsDNA molecule. Copyright © 2017 Elsevier B.V. All rights reserved.

[Constitutional mismatch repair deficiency syndrome].

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Jongmans, Marjolijn C; Gidding, Corrie E; Loeffen, Jan; Wesseling, Pieter; Mensenkamp, Arjen; Hoogerbrugge, Nicoline

2015-01-01

Constitutional mismatch repair deficiency (CMMR-D) syndrome is characterised by a significantly increased risk for developing cancer in childhood. It arises when both parents have a mutation in the same mismatch repair gene and pass it on to their child. An 8-year-old girl was diagnosed with CMMR-D syndrome after she developed a brain tumour at the age of 4 and a T-cell non-Hodgkin lymphoma at the age of 6. She had multiple hyperpigmented skin lesions and died of myelodysplastic syndrome at the age of 11. In children with cancer CMMR-D syndrome can be recognized particularly if there are multiple primary malignancies and skin hyperpigmentations and hypopigmentations. The parents of these children are at high risk for colorectal and endometrial cancer (Lynch syndrome), amongst others.

Homozygous germ-line mutation of the PMS2 mismatch repair gene: a unique case report of constitutional mismatch repair deficiency (CMMRD).

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Ramchander, N C; Ryan, N A J; Crosbie, E J; Evans, D G

2017-04-05

Constitutional mismatch repair deficiency syndrome results from bi-allelic inheritance of mutations affecting the key DNA mismatch repair genes: MLH1, MSH2, MSH6 or PMS2. Individuals with bi-allelic mutations have a dysfunctional mismatch repair system from birth; as a result, constitutional mismatch repair deficiency syndrome is characterised by early onset malignancies. Fewer than 150 cases have been reported in the literature over the past 20 years. This is the first report of the founder PMS2 mutation - NM_000535.5:c.1500del (p.Val501TrpfsTer94) in exon 11 and its associated cancers in this family. The proband is 30 years old and is alive today. She is of Pakistani ethnic origin and a product of consanguinity. She initially presented aged 24 with painless bleeding per-rectum from colorectal polyps and was referred to clinical genetics. Clinical examination revealed two café-au-lait lesions, lichen planus, and a dermoid cyst. Her sister had been diagnosed in childhood with an aggressive brain tumour followed by colorectal cancer. During follow up, the proband developed 37 colorectal adenomatous polyps, synchronous ovarian and endometrial adenocarcinomas, and ultimately a metachronous gastric adenocarcinoma. DNA sequencing of peripheral lymphocytes revealed a bi-allelic inheritance of the PMS2 mutation NM_000535.5:c.1500del (p.Val501TrpfsTer94) in exon 11. Ovarian tumour tissue demonstrated low microsatellite instability. To date, she has had a total abdominal hysterectomy, bilateral salpingo-oophorectomy, and a total gastrectomy. Aspirin and oestrogen-only hormone replacement therapy provide some chemoprophylaxis and manage postmenopausal symptoms, respectively. An 18-monthly colonoscopy surveillance programme has led to the excision of three high-grade dysplastic colorectal tubular adenomatous polyps. The proband's family pedigree displays multiple relatives with cancers including a likely case of 'true' Turcot syndrome. Constitutional mismatch repair

Mismatch repair genes in Lynch syndrome: a review

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Felipe Cavalcanti Carneiro da Silva

Full Text Available Lynch syndrome represents 1-7% of all cases of colorectal cancer and is an autosomal-dominant inherited cancer predisposition syndrome caused by germline mutations in deoxyribonucleic acid (DNA mismatch repair genes. Since the discovery of the major human genes with DNA mismatch repair function, mutations in five of them have been correlated with susceptibility to Lynch syndrome: mutS homolog 2 (MSH2; mutL homolog 1 (MLH1; mutS homolog 6 (MSH6; postmeiotic segregation increased 2 (PMS2; and postmeiotic segregation increased 1 (PMS1. It has been proposed that one additional mismatch repair gene, mutL homolog 3 (MLH3, also plays a role in Lynch syndrome predisposition, but the clinical significance of mutations in this gene is less clear. According to the InSiGHT database (International Society for Gastrointestinal Hereditary Tumors, approximately 500 different LS-associated mismatch repair gene mutations are known, primarily involving MLH1 (50% and MSH2 (40%, while others account for 10%. Much progress has been made in understanding the molecular basis of Lynch Syndrome. Molecular characterization will be the most accurate way of defining Lynch syndrome and will provide predictive information of greater accuracy regarding the risks of colon and extracolonic cancer and enable optimal cancer surveillance regimens.

DNA Mismatch Repair and Oxidative DNA Damage: Implications for Cancer Biology and Treatment

International Nuclear Information System (INIS)

Bridge, Gemma; Rashid, Sukaina; Martin, Sarah A.

2014-01-01

Many components of the cell, including lipids, proteins and both nuclear and mitochondrial DNA, are vulnerable to deleterious modifications caused by reactive oxygen species. If not repaired, oxidative DNA damage can lead to disease-causing mutations, such as in cancer. Base excision repair and nucleotide excision repair are the two DNA repair pathways believed to orchestrate the removal of oxidative lesions. However, recent findings suggest that the mismatch repair pathway may also be important for the response to oxidative DNA damage. This is particularly relevant in cancer where mismatch repair genes are frequently mutated or epigenetically silenced. In this review we explore how the regulation of oxidative DNA damage by mismatch repair proteins may impact on carcinogenesis. We discuss recent studies that identify potential new treatments for mismatch repair deficient tumours, which exploit this non-canonical role of mismatch repair using synthetic lethal targeting

DNA Mismatch Repair and Oxidative DNA Damage: Implications for Cancer Biology and Treatment

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Bridge, Gemma; Rashid, Sukaina; Martin, Sarah A., E-mail: sarah.martin@qmul.ac.uk [Centre for Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ (United Kingdom)

2014-08-05

Many components of the cell, including lipids, proteins and both nuclear and mitochondrial DNA, are vulnerable to deleterious modifications caused by reactive oxygen species. If not repaired, oxidative DNA damage can lead to disease-causing mutations, such as in cancer. Base excision repair and nucleotide excision repair are the two DNA repair pathways believed to orchestrate the removal of oxidative lesions. However, recent findings suggest that the mismatch repair pathway may also be important for the response to oxidative DNA damage. This is particularly relevant in cancer where mismatch repair genes are frequently mutated or epigenetically silenced. In this review we explore how the regulation of oxidative DNA damage by mismatch repair proteins may impact on carcinogenesis. We discuss recent studies that identify potential new treatments for mismatch repair deficient tumours, which exploit this non-canonical role of mismatch repair using synthetic lethal targeting.

Endometrial tumour BRAF mutations and MLH1 promoter methylation as predictors of germline mismatch repair gene mutation status: a literature review.

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Metcalf, Alexander M; Spurdle, Amanda B

2014-03-01

Colorectal cancer (CRC) that displays high microsatellite instability (MSI-H) can be caused by either germline mutations in mismatch repair (MMR) genes, or non-inherited transcriptional silencing of the MLH1 promoter. A correlation between MLH1 promoter methylation, specifically the 'C' region, and BRAF V600E status has been reported in CRC studies. Germline MMR mutations also greatly increase risk of endometrial cancer (EC), but no systematic review has been undertaken to determine if these tumour markers may be useful predictors of MMR mutation status in EC patients. Endometrial cancer cohorts meeting review inclusion criteria encompassed 2675 tumours from 20 studies for BRAF V600E, and 447 tumours from 11 studies for MLH1 methylation testing. BRAF V600E mutations were reported in 4/2675 (0.1%) endometrial tumours of unknown MMR mutation status, and there were 7/823 (0.9%) total sequence variants in exon 11 and 27/1012 (2.7%) in exon 15. Promoter MLH1 methylation was not observed in tumours from 32 MLH1 mutation carriers, or for 13 MSH2 or MSH6 mutation carriers. MMR mutation-negative individuals with tumour MLH1 and PMS2 IHC loss displayed MLH1 methylation in 48/51 (94%) of tumours. We have also detailed specific examples that show the importance of MLH1 promoter region, assay design, and quantification of methylation. This review shows that BRAF mutations occurs so infrequently in endometrial tumours they can be discounted as a useful marker for predicting MMR-negative mutation status, and further studies of endometrial cohorts with known MMR mutation status are necessary to quantify the utility of tumour MLH1 promoter methylation as a marker of negative germline MMR mutation status in EC patients.

Loss of Cdx2 expression in primary tumors and lymph node metastases is specific for mismatch repair-deficiency in colorectal cancer

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Heather eDawson

2013-10-01

Full Text Available Background: Approximately 20% of all colorectal cancers are hypothesized to arise from the serrated pathway characterized by mutation in BRAF, high-level CpG Island Methylator Phenotype (CIMP and microsatellite instability/mismatch repair (MMR-deficiency. MMR-deficient cancers show frequent losses of Cdx2, a homeodomain transcription factor. Here, we determine the predictive value of Cdx2 expression for MMR-deficiency and investigate changes in expression between primary cancers and matched lymph node metastases. Methods: Immunohistochemistry for Cdx2, Mlh1, Msh2, Msh6, and Pms2 was performed on whole tissue sections from 201 patients with primary colorectal cancer and 59 cases of matched lymph node metastases. Receiver operating characteristic (ROC curve analysis and Area under the Curve (AUC were investigated; association of Cdx2 with clinicopathological features and patient survival was carried out.Results Loss of Cdx2 expression was associated with higher tumor grade (p=0.0002, advanced pT (p=0.0166, and perineural invasion (p=0.0228. Cdx2 loss was an unfavorable prognostic factor in univariate (p=0.0145 and multivariate (p=0.0427; HR (95%CI: 0.58 (0.34-0.98 analysis. The accuracy (AUC for discriminating MMR-proficient and –deficient cancers was 87% (OR (95%CI:0.96 (0.95-0.98; p<0.0001. Specificity and negative predictive value for MMR-deficiency was 99.1% and 96.3%. 174 patients had MMR-proficient cancers, of which 60 (34.5% showed Cdx2 loss. Cdx2 loss in metastases was related to MMR-deficiency (p<0.0001. There was no difference in expression between primary tumors and matched metastases.Conclusion: Loss of Cdx2 is a sensitive and specific predictor of MMR-deficiency, but is not limited to these tumors, suggesting that events upstream of the development of MSI may impact Cdx2 expression.

Common variants in mismatch repair genes associated with increased risk of sperm DNA damage and male infertility

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Ji Guixiang

2012-05-01

Full Text Available Abstract Background The mismatch repair (MMR pathway plays an important role in the maintenance of the genome integrity, meiotic recombination and gametogenesis. This study investigated whether genetic variations in MMR genes are associated with an increased risk of sperm DNA damage and male infertility. Methods We selected and genotyped 21 tagging single nucleotide polymorphisms (SNPs in five MMR genes (MLH1, MLH3, PMS2, MSH4 and MSH5 using the SNPstream 12-plex platform in a case-control study of 1,292 idiopathic infertility patients and 480 fertile controls in a Chinese population. Sperm DNA damage levels were detected with the Tdt-mediated dUTP nick end labelling (TUNEL assay in 450 cases. Fluorescence resonance energy transfer (FRET and co-immunoprecipitation techniques were employed to determine the effects of functional variants. Results One intronic SNP in MLH1 (rs4647269 and two non-synonymous SNPs in PMS2 (rs1059060, Ser775Asn and MSH5 (rs2075789, Pro29Ser seem to be risk factors for the development of azoospermia or oligozoospermia. Meanwhile, we also identified a possible contribution of PMS2 rs1059060 to the risk of male infertility with normal sperm count. Among patients with normal sperm count, MLH1 rs4647269 and PMS2 rs1059060 were associated with increased sperm DNA damage. Functional analysis revealed that the PMS2 rs1059060 can affect the interactions between MLH1 and PMS2. Conclusions Our results provide evidence supporting the involvement of genetic polymorphisms in MMR genes in the aetiology of male infertility.

Café-au-lait macules and pediatric malignancy caused by biallelic mutations in the DNA mismatch repair (MMR) gene PMS2.

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Jackson, Carl-Christian; Holter, Spring; Pollett, Aaron; Clendenning, Mark; Chou, Shirley; Senter, Leigha; Ramphal, Raveena; Gallinger, Steven; Boycott, Kym

2008-06-01

A 14-year-old male presented with a T4 sigmoid adenocarcinoma, PMS2 protein and high frequency microsatellite instability. Germline analysis identified biallelic PMS2 missense mutations. A new cancer syndrome caused by biallelic mutations in the mismatch repair genes, including PMS2, is now emerging and is characterized by café-au-lait macules, colonic polyps and a distinctive tumor spectrum. (c) 2007 Wiley-Liss, Inc.

Genomic Instability Promoted by Overexpression of Mismatch Repair Factors in Yeast: A Model for Understanding Cancer Progression.

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Chakraborty, Ujani; Dinh, Timothy A; Alani, Eric

2018-04-13

Mismatch repair (MMR) proteins act in spellchecker roles to excise misincorporation errors that occur during DNA replication. Curiously, large-scale analyses of a variety of cancers showed that increased expression of MMR proteins often correlated with tumor aggressiveness, metastasis, and early recurrence. To better understand these observations, we used the TCGA and GENT databases to analyze MMR protein expression in cancers. We found that the MMR genes MSH2 and MSH6 are overexpressed more frequently than MSH3 , and that MSH2 and MSH6 are often co-overexpressed as a result of copy number amplifications of these genes. These observations encouraged us to test the effects of upregulating MMR protein levels in baker's yeast, where we can sensitively monitor genome instability phenotypes associated with cancer initiation and progression. Msh6 overexpression (2 to 4-fold) almost completely disrupted mechanisms that prevent recombination between divergent DNA sequences by interacting with the DNA polymerase processivity clamp PCNA and by sequestering the Sgs1 helicase. Importantly, co-overexpression of Msh2 and Msh6 (∼8-fold) conferred, in a PCNA interaction dependent manner, several genome instability phenotypes including increased mutation rate, increased sensitivity to the DNA replication inhibitor hydroxyurea and the DNA damaging agents methyl methanesulfonate and 4-nitroquinoline N-oxide, and elevated loss of heterozygosity. Msh2 and Msh6 co-overexpression also altered the cell cycle distribution of exponentially growing cells, resulting in an increased fraction of unbudded cells, consistent with a larger percentage of cells in G1. These novel observations suggested that overexpression of MSH factors affected the integrity of the DNA replication fork, causing genome instability phenotypes that could be important for promoting cancer progression. Copyright © 2018, Genetics.

Down-regulation of DNA mismatch repair enhances initiation and growth of neuroblastoma and brain tumour multicellular spheroids.

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Samuel L Collins

Full Text Available Multicellular tumour spheroid (MCTS cultures are excellent model systems for simulating the development and microenvironmental conditions of in vivo tumour growth. Many documented cell lines can generate differentiated MCTS when cultured in suspension or in a non-adhesive environment. While physiological and biochemical properties of MCTS have been extensively characterized, insight into the events and conditions responsible for initiation of these structures is lacking. MCTS are formed by only a small subpopulation of cells during surface-associated growth but the processes responsible for this differentiation are poorly understood and have not been previously studied experimentally. Analysis of gene expression within spheroids has provided clues but to date it is not known if the observed differences are a cause or consequence of MCTS growth. One mechanism linked to tumourigenesis in a number of cancers is genetic instability arising from impaired DNA mismatch repair (MMR. This study aimed to determine the role of MMR in MCTS initiation and development. Using surface-associated N2a and CHLA-02-ATRT culture systems we have investigated the impact of impaired MMR on MCTS growth. Analysis of the DNA MMR genes MLH1 and PMS2 revealed both to be significantly down-regulated at the mRNA level compared with non-spheroid-forming cells. By using small interfering RNA (siRNA against these genes we show that silencing of MLH1 and PMS2 enhances both MCTS initiation and subsequent expansion. This effect was prolonged over several passages following siRNA transfection. Down-regulation of DNA MMR can contribute to tumour initiation and progression in N2a and CHLA-02-ATRT MCTS models. Studies of surface-associated MCTS differentiation may have broader applications in studying events in the initiation of cancer foci.

Curcumin Chemosensitizes 5-Fluorouracil Resistant MMR-Deficient Human Colon Cancer Cells in High Density Cultures

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Shakibaei, Mehdi; Buhrmann, Constanze; Kraehe, Patricia; Shayan, Parviz; Lueders, Cora; Goel, Ajay

2014-01-01

OBJECTIVE: Treatment of colorectal cancer (CRC) remains a clinical challenge, as more than 15% of patients are resistant to 5-Fluorouracil (5-FU)-based chemotherapeutic regimens, and tumor recurrence rates can be as high as 50-60%. Cancer stem cells (CSC) are capable of surviving conventional chemotherapies that permits regeneration of original tumors. Therefore, we investigated the effectiveness of 5-FU and plant polyphenol (curcumin) in context of DNA mismatch repair (MMR) status and CSC ac...

Interobserver variability in the evaluation of mismatch repair protein immunostaining

DEFF Research Database (Denmark)

Klarskov, Louise Laurberg; Ladelund, Steen; Holck, Susanne

2010-01-01

Immunohistochemical staining for mismatch repair proteins has during recent years been established as a routine analysis in many pathology laboratories with the aim to identify tumors linked to the hereditary nonpolyposis colorectal cancer syndrome. Despite widespread application, data on reliabi......Immunohistochemical staining for mismatch repair proteins has during recent years been established as a routine analysis in many pathology laboratories with the aim to identify tumors linked to the hereditary nonpolyposis colorectal cancer syndrome. Despite widespread application, data...... on reliability are lacking. We therefore evaluated interobserver variability among 6 pathologists, 3 experienced gastrointestinal pathologists and 3 residents. In total, 225 immunohistochemically stained colorectal cancers were evaluated as having normal, weak, loss of, or nonevaluable mismatch repair protein...... variability was considerable, though experienced pathologists and residents reached the same level of consensus. Because results from immunohistochemical mismatch repair protein stainings are used for decisions on mutation analysis and as an aid in the interpretation of gene variants of unknown significance...

Measuring strand discontinuity-directed mismatch repair in yeast Saccharomyces cerevisiae by cell-free nuclear extracts.

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Yuan, Fenghua; Lai, Fangfang; Gu, Liya; Zhou, Wen; El Hokayem, Jimmy; Zhang, Yanbin

2009-05-01

Mismatch repair corrects biosynthetic errors generated during DNA replication, whose deficiency causes a mutator phenotype and directly underlies hereditary non-polyposis colorectal cancer and sporadic cancers. Because of remarkably high conservation of the mismatch repair machinery between the budding yeast (Saccharomyces cerevisiae) and humans, the study of mismatch repair in yeast has provided tremendous insights into the mechanisms of this repair pathway in humans. In addition, yeast cells possess an unbeatable advantage over human cells in terms of the easy genetic manipulation, the availability of whole genome deletion strains, and the relatively low cost for setting up the system. Although many components of eukaryotic mismatch repair have been identified, it remains unclear if additional factors, such as DNA helicase(s) and redundant nuclease(s) besides EXO1, participate in eukaryotic mismatch repair. To facilitate the discovery of novel mismatch repair factors, we developed a straightforward in vitro cell-free repair system. Here, we describe the practical protocols for preparation of yeast cell-free nuclear extracts and DNA mismatch substrates, and the in vitro mismatch repair assay. The validity of the cell-free system was confirmed by the mismatch repair deficient yeast strain (Deltamsh2) and the complementation assay with purified yeast MSH2-MSH6.

Risk of metachronous colon cancer following surgery for rectal cancer in mismatch repair gene mutation carriers.

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Win, Aung Ko; Parry, Susan; Parry, Bryan; Kalady, Matthew F; Macrae, Finlay A; Ahnen, Dennis J; Young, Graeme P; Lipton, Lara; Winship, Ingrid; Boussioutas, Alex; Young, Joanne P; Buchanan, Daniel D; Arnold, Julie; Le Marchand, Loïc; Newcomb, Polly A; Haile, Robert W; Lindor, Noralane M; Gallinger, Steven; Hopper, John L; Jenkins, Mark A

2013-06-01

Despite regular surveillance colonoscopy, the metachronous colorectal cancer risk for mismatch repair (MMR) gene mutation carriers after segmental resection for colon cancer is high and total or subtotal colectomy is the preferred option. However, if the index cancer is in the rectum, management decisions are complicated by considerations of impaired bowel function. We aimed to estimate the risk of metachronous colon cancer for MMR gene mutation carriers who underwent a proctectomy for index rectal cancer. This retrospective cohort study comprised 79 carriers of germline mutation in a MMR gene (18 MLH1, 55 MSH2, 4 MSH6, and 2 PMS2) from the Colon Cancer Family Registry who had had a proctectomy for index rectal cancer. Cumulative risks of metachronous colon cancer were calculated using the Kaplan-Meier method. During median 9 years (range 1-32 years) of observation since the first diagnosis of rectal cancer, 21 carriers (27 %) were diagnosed with metachronous colon cancer (incidence 24.25, 95 % confidence interval [CI] 15.81-37.19 per 1,000 person-years). Cumulative risk of metachronous colon cancer was 19 % (95 % CI 9-31 %) at 10 years, 47 (95 % CI 31-68 %) at 20 years, and 69 % (95 % CI 45-89 %) at 30 years after surgical resection. The frequency of surveillance colonoscopy was 1 colonoscopy per 1.16 years (95 % CI 1.01-1.31 years). The AJCC stages of the metachronous cancers, where available, were 72 % stage I, 22 % stage II, and 6 % stage III. Given the high metachronous colon cancer risk for MMR gene mutation carriers diagnosed with an index rectal cancer, proctocolectomy may need to be considered.

Integration of Principles of Systems Biology and Radiation Biology: Toward Development of in silico Models to Optimize IUdR-Mediated Radiosensitization of DNA Mismatch Repair Deficient (Damage Tolerant) Human Cancers

International Nuclear Information System (INIS)

Kinsella, Timothy J.; Gurkan-Cavusoglu, Evren; Du, Weinan; Loparo, Kenneth A.

2011-01-01

Over the last 7 years, we have focused our experimental and computational research efforts on improving our understanding of the biochemical, molecular, and cellular processing of iododeoxyuridine (IUdR) and ionizing radiation (IR) induced DNA base damage by DNA mismatch repair (MMR). These coordinated research efforts, sponsored by the National Cancer Institute Integrative Cancer Biology Program (ICBP), brought together system scientists with expertise in engineering, mathematics, and complex systems theory and translational cancer researchers with expertise in radiation biology. Our overall goal was to begin to develop computational models of IUdR- and/or IR-induced base damage processing by MMR that may provide new clinical strategies to optimize IUdR-mediated radiosensitization in MMR deficient (MMR − ) “damage tolerant” human cancers. Using multiple scales of experimental testing, ranging from purified protein systems to in vitro (cellular) and to in vivo (human tumor xenografts in athymic mice) models, we have begun to integrate and interpolate these experimental data with hybrid stochastic biochemical models of MMR damage processing and probabilistic cell cycle regulation models through a systems biology approach. In this article, we highlight the results and current status of our integration of radiation biology approaches and computational modeling to enhance IUdR-mediated radiosensitization in MMR − damage tolerant cancers.

Alcohol Consumption and the Risk of Colorectal Cancer for Mismatch Repair Gene Mutation Carriers.

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Dashti, S Ghazaleh; Buchanan, Daniel D; Jayasekara, Harindra; Ait Ouakrim, Driss; Clendenning, Mark; Rosty, Christophe; Winship, Ingrid M; Macrae, Finlay A; Giles, Graham G; Parry, Susan; Casey, Graham; Haile, Robert W; Gallinger, Steven; Le Marchand, Loïc; Thibodeau, Stephen N; Lindor, Noralane M; Newcomb, Polly A; Potter, John D; Baron, John A; Hopper, John L; Jenkins, Mark A; Win, Aung Ko

2017-03-01

Background: People with germline mutation in one of the DNA mismatch repair (MMR) genes have increased colorectal cancer risk. For these high-risk people, study findings of the relationship between alcohol consumption and colorectal cancer risk have been inconclusive. Methods: 1,925 MMR gene mutations carriers recruited into the Colon Cancer Family Registry who had completed a questionnaire on lifestyle factors were included. Weighted Cox proportional hazard regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between alcohol consumption and colorectal cancer. Results: Colorectal cancer was diagnosed in 769 carriers (40%) at a mean (SD) age of 42.6 (10.3) years. Compared with abstention, ethanol consumption from any alcoholic beverage up to 14 g/day and >28 g/day was associated with increased colorectal cancer risk (HR, 1.50; 95% CI, 1.09-2.07 and 1.69; 95% CI, 1.07-2.65, respectively; P trend = 0.05), and colon cancer risk (HR, 1.78; 95% CI, 1.27-2.49 and 1.94; 95% CI, 1.19-3.18, respectively; P trend = 0.02). However, there was no clear evidence for an association with rectal cancer risk. Also, there was no evidence for associations between consumption of individual alcoholic beverage types (beer, wine, spirits) and colorectal, colon, or rectal cancer risk. Conclusions: Our data suggest that alcohol consumption, particularly more than 28 g/day of ethanol (∼2 standard drinks of alcohol in the United States), is associated with increased colorectal cancer risk for MMR gene mutation carriers. Impact: Although these data suggested that alcohol consumption in MMR carriers was associated with increased colorectal cancer risk, there was no evidence of a dose-response, and not all types of alcohol consumption were associated with increased risk. Cancer Epidemiol Biomarkers Prev; 26(3); 366-75. ©2016 AACR . ©2016 American Association for Cancer Research.

Mismatch Repair Balances Leading and Lagging Strand DNA Replication Fidelity

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2012-10-11

Rev Mol Cell Biol 7: 335–346. 7. Li GM (2008) Mechanisms and functions of DNA mismatch repair. Cell Res 18: 85–98. 8. Pavlov YI, Mian IM, Kunkel TA...11: 165–170. 41. Li F, Tian L, Gu L, Li GM (2009) Evidence that nucleosomes inhibit mismatch repair in eukaryotic cells. J Biol Chem 284: 33056–33061

Relationship among mismatch repair deficiency, CDX2 loss, p53 and E-cadherin in colon carcinoma and suitability of using a double panel of mismatch repair proteins by immunohistochemistry.

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Sayar, Ilyas; Akbas, Emin Murat; Isik, Arda; Gokce, Aysun; Peker, Kemal; Demirtas, Levent; Gürbüzel, Mehmet

2015-09-01

Biomarkers such as mismatch repair proteins, CDX2, p53, and E-cadherin are blamed for colon cancers, but the relationships of these biomarkers with each other and with pathological risk factors in colon carcinoma are still not clear. The aim of this study was to evaluate the association of these biomarkers with each other by using immunohistochemical staining and to compare their expression with pathological risk factors for colonic adenocarcinoma. We also aimed to study the usability of a double panel of mismatch repair proteins. One hundred and eleven cases with colonic adenocarcinoma were examined. There was a statistically significant relationship between tumor histological differentiation and perineural invasion, vascular invasion, mismatch repair deficiency, p53, CDX2, and E-cadherin (p < 0.05). PMS2 and MSH6 loss covered 100% of cases with mismatch repair deficiency. Mismatch repair deficiency was correlated with CDX2 loss and E-cadherin expression (p < 0.05). It was also observed that cases with PMS2 loss covered all the cases with CDX2 loss. In conclusion, this double panel may be used instead of a quadruple panel for detecting mismatch repair deficiency. Association of CDX2 and PMS2 in the present study is necessary to conduct further genetic and pathological studies focusing on these two markers together.

Clinical problems of colorectal cancer and endometrial cancer cases with unknown cause of tumor mismatch repair deficiency (suspected Lynch syndrome

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Buchanan DD

2014-10-01

Full Text Available Daniel D Buchanan,1,2 Christophe Rosty,1,3,4 Mark Clendenning,1 Amanda B Spurdle,5 Aung Ko Win2 1Oncogenomics Group, Genetic Epidemiology Laboratory, Department of Pathology, The University of Melbourne, Parkville, VIC, Australia; 2Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Parkville, VIC, Australia; 3Envoi Specialist Pathologists, Herston, QLD, Australia; 4School of Medicine, University of Queensland, Herston, QLD, Australia; 5Molecular Cancer Epidemiology Laboratory, Genetics and Computational Biology Division, QIMR Berghofer Medical Research Institute, Herston, QLD, AustraliaAbstract: Carriers of a germline mutation in one of the DNA mismatch repair (MMR genes have a high risk of developing numerous different cancers, predominantly colorectal cancer and endometrial cancer (known as Lynch syndrome. MMR gene mutation carriers develop tumors with MMR deficiency identified by tumor microsatellite instability or immunohistochemical loss of MMR protein expression. Tumor MMR deficiency is used to identify individuals most likely to carry an MMR gene mutation. However, MMR deficiency can also result from somatic inactivation, most commonly methylation of the MLH1 gene promoter. As tumor MMR testing of all incident colorectal and endometrial cancers (universal screening is becoming increasingly adopted, a growing clinical problem is emerging for individuals who have tumors that show MMR deficiency who are subsequently found not to carry an MMR gene mutation after genetic testing using the current diagnostic approaches (Sanger sequencing and multiplex ligation-dependent probe amplification and who also show no evidence of MLH1 methylation. The inability to determine the underlying cause of tumor MMR deficiency in these "Lynch-like" or "suspected Lynch syndrome" cases has significant implications on the clinical management of these individuals and their relatives. When the

Distinct effects of the recurrent Mlh1G67R mutation on MMR functions, cancer, and meiosis

OpenAIRE

Avdievich, Elena; Reiss, Cora; Scherer, Stefan J.; Zhang, Yongwei; Maier, Sandra M.; Jin, Bo; Hou, Harry; Rosenwald, Andreas; Riedmiller, Hubertus; Kucherlapati, Raju; Cohen, Paula E.; Edelmann, Winfried; Kneitz, Burkhard

2008-01-01

Mutations in the human DNA mismatch repair (MMR) gene MLH1 are associated with hereditary nonpolyposis colorectal cancer (Lynch syndrome, HNPCC) and a significant proportion of sporadic colorectal cancer. The inactivation of MLH1 results in the accumulation of somatic mutations in the genome of tumor cells and resistance to the genotoxic effects of a variety of DNA damaging agents. To study the effect of MLH1 missense mutations on cancer susceptibility, we generated a mouse line carrying the ...

BRCA2, EGFR, and NTRK mutations in mismatch repair-deficient colorectal cancers with MSH2 or MLH1 mutations.

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Deihimi, Safoora; Lev, Avital; Slifker, Michael; Shagisultanova, Elena; Xu, Qifang; Jung, Kyungsuk; Vijayvergia, Namrata; Ross, Eric A; Xiu, Joanne; Swensen, Jeffrey; Gatalica, Zoran; Andrake, Mark; Dunbrack, Roland L; El-Deiry, Wafik S

2017-06-20

Deficient mismatch repair (MMR) and microsatellite instability (MSI) contribute to ~15% of colorectal cancer (CRCs). We hypothesized MSI leads to mutations in DNA repair proteins including BRCA2 and cancer drivers including EGFR. We analyzed mutations among a discovery cohort of 26 MSI-High (MSI-H) and 558 non-MSI-H CRCs profiled at Caris Life Sciences. Caris-profiled MSI-H CRCs had high mutation rates (50% vs 14% in non-MSI-H, P MLH1-mutant CRCs showed higher mutation rates in BRCA2 compared to non-MSH2/MLH1-mutant tumors (38% vs 6%, P MLH1-mutant CRCs included 75 unique mutations not known to occur in breast or pancreatic cancer per COSMIC v73. Only 5 deleterious BRCA2 mutations in CRC were previously reported in the BIC database as germ-line mutations in breast cancer. Some BRCA2 mutations were predicted to disrupt interactions with partner proteins DSS1 and RAD51. Some CRCs harbored multiple BRCA2 mutations. EGFR was mutated in 45.5% of MSH2/MLH1-mutant and 6.5% of non-MSH2/MLH1-mutant tumors (P MLH1-mutant CRC including NTRK1 I699V, NTRK2 P716S, and NTRK3 R745L. Our findings have clinical relevance regarding therapeutic targeting of BRCA2 vulnerabilities, EGFR mutations or other identified oncogenic drivers such as NTRK in MSH2/MLH1-mutant CRCs or other tumors with mismatch repair deficiency.

Clinicopathological characteristics of patients with upper urinary tract urothelial cancer with loss of immunohistochemical expression of the DNA mismatch repair proteins in universal screening.

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Urakami, Shinji; Inoshita, Naoko; Oka, Suguru; Miyama, Yu; Nomura, Sachio; Arai, Masami; Sakaguchi, Kazushige; Kurosawa, Kazuhiro; Okaneya, Toshikazu

2018-02-01

To assess the detection rate of putative Lynch syndrome-associated upper urinary tract urothelial cancer among all upper urinary tract urothelial cancers and to examine its clinicopathological characteristics. A total of 143 patients with upper urinary tract urothelial cancer who had received total nephroureterectomy were immunohistochemically stained for the expression of mismatch repair proteins MLH1, PMS2, MSH2 and MSH6. For all suspected mismatch repair-deficient cases, MMR genetic testing was recommended and clinicopathological features were examined. Loss of mismatch repair proteins was found in seven patients (5%) who were thus categorized as putative Lynch syndrome-associated upper urinary tract urothelial cancer. Five of these patients showed dual loss of MSH2/MSH6. Two patients were confirmed to be MSH2 germline mutation carriers. Histologically, all seven tumors were low-grade atypical urothelial carcinoma and showed its unique histological features, such as an inverted papilloma-like growth pattern and a villous to papillary structure with mild stratification of tumor cells. Six tumors had no invasion of the muscularis propria. No recurrence or cancer-related deaths were reported in these seven patients. Just three patients met the revised Amsterdam criteria. This is the first report that universally examined mismatch repair immunohistochemical screening for upper urinary tract urothelial cancers. The prevalence (5%) of putative Lynch syndrome-associated upper urinary tract urothelial cancers is much higher than we had expected. We ascertained that putative Lynch syndrome-associated upper urinary tract urothelial cancers were clinically in the early stage and histologically classified into low-grade malignancy with its characteristic pathological features. The clinicopathological characteristics that we found in the present study could become additional possible markers in the diagnosis of Lynch syndrome-associated upper urinary tract urothelial cancers

Characterization of a Highly Conserved Binding Site of Mlh1 Required for Exonuclease I-Dependent Mismatch Repair

DEFF Research Database (Denmark)

Dherin, Claudine; Gueneau, Emeric; Francin, Mathilde

2009-01-01

Mlh1 is an essential factor of mismatch repair (MMR) and meiotic recombination. It interacts through its C-terminal region with MutL homologs and proteins involved in DNA repair and replication. In this study, we identified the site of yeast Mlh1 critical for the interaction with Exo1, Ntg2......, and Sgs1 proteins, designated as site S2 by reference to the Mlh1/Pms1 heterodimerization site S1. We show that site S2 is also involved in the interaction between human MLH1 and EXO1 or BLM. Binding at this site involves a common motif on Mlh1 partners that we called the MIP-box for the Mlh1 interacting...... protein box. Direct and specific interactions between yeast Mlh1 and peptides derived from Exo1, Ntg2, and Sgs1 and between human MLH1 and peptide derived from EXO1 and BLM were measured with K(d) values ranging from 8.1 to 17.4 microM. In Saccharomyces cerevisiae, a mutant of Mlh1 targeted at site S2...

DNA Damage Induced by Alkylating Agents and Repair Pathways

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Kondo, Natsuko; Takahashi, Akihisa; Ono, Koji; Ohnishi, Takeo

2010-01-01

The cytotoxic effects of alkylating agents are strongly attenuated by cellular DNA repair processes, necessitating a clear understanding of the repair mechanisms. Simple methylating agents form adducts at N- and O-atoms. N-methylations are removed by base excision repair, AlkB homologues, or nucleotide excision repair (NER). O6-methylguanine (MeG), which can eventually become cytotoxic and mutagenic, is repaired by O6-methylguanine-DNA methyltransferase, and O6MeG:T mispairs are recognized by the mismatch repair system (MMR). MMR cannot repair the O6MeG/T mispairs, which eventually lead to double-strand breaks. Bifunctional alkylating agents form interstrand cross-links (ICLs) which are more complex and highly cytotoxic. ICLs are repaired by complex of NER factors (e.g., endnuclease xeroderma pigmentosum complementation group F-excision repair cross-complementing rodent repair deficiency complementation group 1), Fanconi anemia repair, and homologous recombination. A detailed understanding of how cells cope with DNA damage caused by alkylating agents is therefore potentially useful in clinical medicine. PMID:21113301

DNA mismatch repair, genome instability and cancer in zebrafish

NARCIS (Netherlands)

Feitsma, H.

2008-01-01

The objective of this study was to find out whether the zebrafish can be an appropriate model for studying DNA repair and cancer. For this purpose three fish lines were used that lack components of an important mechanism for the repair of small DNA damage: DNA mismatch repair. These fish are

Constitutional mismatch repair deficiency in a healthy child : On the spot diagnosis?

NARCIS (Netherlands)

Suerink, Manon; Potjer, Thomas P.; Versluijs, A. B.; Ten Broeke, Sanne W.; Tops, Carli M.; Wimmer, K.; Nielsen, M.

2018-01-01

Constitutional mismatch repair deficiency (CMMRD) is a rare, recessively inherited childhood cancer predisposition syndrome caused by biallelic germline mutations in one of the mismatch repair genes. The CMMRD phenotype overlaps with that of neurofibromatosis type 1 (NF1), since many patients have

Constitutional mismatch repair deficiency syndrome: Do we know it?

Science.gov (United States)

Ramachandra, C; Challa, Vasu Reddy; Shetty, Rachan

2014-04-01

Constitutional mismatch repair deficiency syndrome is a rare autosomal recessive syndrome caused by homozygous mutations in mismatch repair genes. This is characterized by the childhood onset of brain tumors, colorectal cancers, cutaneous manifestations of neurofibromatosis-1 like café au lait spots, hematological malignancies, and occasionally other rare malignancies. Here, we would like to present a family in which the sibling had glioblastoma, and the present case had acute lymphoblastic lymphoma and colorectal cancer. We would like to present this case because of its rarity and would add to literature.

Agenesis of the corpus callosum and gray matter heterotopia in three patients with constitutional mismatch repair deficiency syndrome.

Science.gov (United States)

Baas, Annette F; Gabbett, Michael; Rimac, Milan; Kansikas, Minttu; Raphael, Martine; Nievelstein, Rutger Aj; Nicholls, Wayne; Offerhaus, Johan; Bodmer, Danielle; Wernstedt, Annekatrin; Krabichler, Birgit; Strasser, Ulrich; Nyström, Minna; Zschocke, Johannes; Robertson, Stephen P; van Haelst, Mieke M; Wimmer, Katharina

2013-01-01

Constitutional mismatch repair deficiency (CMMR-D) syndrome is a rare inherited childhood cancer predisposition caused by biallelic germline mutations in one of the four mismatch repair (MMR)-genes, MLH1, MSH2, MSH6 or PMS2. Owing to a wide tumor spectrum, the lack of specific clinical features and the overlap with other cancer predisposing syndromes, diagnosis of CMMR-D is often delayed in pediatric cancer patients. Here, we report of three new CMMR-D patients all of whom developed more than one malignancy. The common finding in these three patients is agenesis of the corpus callosum (ACC). Gray matter heterotopia is present in two patients. One of the 57 previously reported CMMR-D patients with brain tumors (therefore all likely had cerebral imaging) also had ACC. With the present report the prevalence of cerebral malformations is at least 4/60 (6.6%). This number is well above the population birth prevalence of 0.09-0.36 live births with these cerebral malformations, suggesting that ACC and heterotopia are features of CMMR-D. Therefore, the presence of cerebral malformations in pediatric cancer patients should alert to the possible diagnosis of CMMR-D. ACC and gray matter heterotopia are the first congenital malformations described to occur at higher frequency in CMMR-D patients than in the general population. Further systematic evaluations of CMMR-D patients are needed to identify possible other malformations associated with this syndrome.

Balancing repair and tolerance of DNA damage caused by alkylating agents

OpenAIRE

Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D.

2012-01-01

Alkylating agents constitute a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER) and mismatch repair (MMR), respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial ...

Distinct mutational signatures characterize concurrent loss of polymerase proofreading and mismatch repair.

Science.gov (United States)

Haradhvala, N J; Kim, J; Maruvka, Y E; Polak, P; Rosebrock, D; Livitz, D; Hess, J M; Leshchiner, I; Kamburov, A; Mouw, K W; Lawrence, M S; Getz, G

2018-05-01

Fidelity of DNA replication is maintained using polymerase proofreading and the mismatch repair pathway. Tumors with loss of function of either mechanism have elevated mutation rates with characteristic mutational signatures. Here we report that tumors with concurrent loss of both polymerase proofreading and mismatch repair function have mutational patterns that are not a simple sum of the signatures of the individual alterations, but correspond to distinct, previously unexplained signatures: COSMIC database signatures 14 and 20. We then demonstrate that in all five cases in which the chronological order of events could be determined, polymerase epsilon proofreading alterations precede the defect in mismatch repair. Overall, we illustrate that multiple distinct mutational signatures can result from different combinations of a smaller number of mutational processes (of either damage or repair), which can influence the interpretation and discovery of mutational signatures.

Upper tract urothelial carcinomas: frequency of association with mismatch repair protein loss and lynch syndrome.

Science.gov (United States)

Harper, Holly L; McKenney, Jesse K; Heald, Brandie; Stephenson, Andrew; Campbell, Steven C; Plesec, Thomas; Magi-Galluzzi, Cristina

2017-01-01

Increased risk for upper tract urothelial carcinoma is described in patients with Lynch syndrome, caused by germline mutations in mismatch repair genes. We aimed to identify the frequency of mismatch repair protein loss in upper tract urothelial carcinoma and its potential for identifying an association with Lynch syndrome. We queried our database to identify upper tract urothelial carcinomas. Patients were cross-referenced for history of colorectal carcinoma or other common Lynch syndrome-associated neoplasms to enrich for potential Lynch syndrome cases. Tumor histopathologic characteristics were reviewed and each case was analyzed for loss of mismatch repair proteins, MLH1, MSH2, MSH6, and PMS2, by immunohistochemistry. Of 444 patients with upper tract urothelial carcinoma, a subset of 215 (encompassing 30 with upper tract urothelial carcinoma and another common Lynch syndrome-associated neoplasm) was analyzed for loss of mismatch repair protein expression. Of 30 patients with Lynch syndrome-associated neoplasms, six had documented Lynch syndrome, including two with Muir-Torre syndrome. Mismatch repair protein loss was identified in 7% of total upper tract urothelial carcinomas and 30% of patients with Lynch syndrome-associated neoplasms (including all patients with Lynch syndrome/Muir-Torre syndrome). Of patients without history of Lynch syndrome-associated neoplasms, 5 of 184 (2.7%) had loss of mismatch repair protein expression. Twelve cases with mismatch repair protein loss demonstrated loss of MSH2 and MSH6, and 2 had isolated loss of MSH6. MLH1 and PMS2 expression were consistently retained. Although increased intratumoral lymphocytes, inverted growth, pushing tumor-stromal interface, and lack of nuclear pleomorphism were more commonly seen in cases with mismatch repair protein loss, only intratumoral lymphocytes and presence of pushing borders were statistically significant. MLH1 and PMS2 testing appear to have little utility in upper tract urothelial

Mismatch Repair Deficiency Testing in Patients With Colorectal Cancer and Nonadherence to Testing Guidelines in Young Adults.

Science.gov (United States)

Shaikh, Talha; Handorf, Elizabeth A; Meyer, Joshua E; Hall, Michael J; Esnaola, Nestor F

2018-02-08

Mismatch repair (MMR) deficiency of DNA has been observed in up to 15% of sporadic colorectal cancers (CRCs) and is a characteristic feature of Lynch syndrome, which has a higher incidence in young adults (age, testing in adults with CRC and analyze nonadherence to long-standing testing guidelines in younger adults using a contemporary national data set to help identify potential risk factors for nonadherence to newly implemented universal testing guidelines. Adult (age, testing status were identified using the National Cancer Database. The study was conducted from March 16, 2016, to March 1, 2017. Patient sociodemographic, facility, tumor, and treatment characteristics. The primary outcome of interest was receipt of MMR deficiency testing. Multivariable logistic regression was used to identify independent predictors of testing in adult and/or young adult patients. A total of 152 993 adults with CRC were included in the study (78 579 [51.4%] men; mean [SD] age, 66.9 [13.9] years). Of these patients, only 43 143 (28.2%) underwent MMR deficiency testing; the proportion of patients tested increased between 2010 and 2012 (22.3% vs 33.1%; Ptesting; the proportion tested increased between 2010 and 2012 (36.1% vs 48.0%; P testing, whereas older age (OR, 0.31; 95% CI, 0.26-0.37); Medicare (OR, 0.89; 95% CI, 0.84-0.95), Medicaid (OR, 0.83; 95% CI, 0.73-0.93), or uninsured (OR, 0.78; 95% CI, 0.66-0.92) status; nonacademic vs academic/research facility type (OR, 0.44; 95% CI, 0.34-0.56); rectosigmoid or rectal tumor location (OR, 0.76; 95% CI, 0.68-0.86); unknown grade (OR, 0.61; 95% CI, 0.53-0.69); and nonreceipt of definitive surgery (OR, 0.33; 95% CI, 0.30-0.37) were associated with underuse of MMR deficiency testing. Despite recent endorsement of universal use of MMR deficiency testing in patients with CRC and well-established guidelines aimed at high-risk populations, overall utilization of testing is poor and significant underuse of testing among young adults

Physical interaction between components of DNA mismatch repair and nucleotide excision repair

International Nuclear Information System (INIS)

Bertrand, P.; Tishkoff, D.X.; Filosi, N.; Dasgupta, R.; Kolodner, R.D.

1998-01-01

Nucleotide excision repair (NER) and DNA mismatch repair are required for some common processes although the biochemical basis for this requirement is unknown. Saccharomyces cerevisiae RAD14 was identified in a two-hybrid screen using MSH2 as 'bait,' and pairwise interactions between MSH2 and RAD1, RAD2, RAD3, RAD10, RAD14, and RAD25 subsequently were demonstrated by two-hybrid analysis. MSH2 coimmunoprecipitated specifically with epitope-tagged versions of RAD2, RAD10, RAD14, and RAD25. MSH2 and RAD10 were found to interact in msh3 msh6 and mlh1 pms1 double mutants, suggesting a direct interaction with MSH2. Mutations in MSH2 increased the UV sensitivity of NER-deficient yeast strains, and msh2 mutations were epistatic to the mutator phenotype observed in NER-deficient strains. These data suggest that MSH2 and possibly other components of DNA mismatch repair exist in a complex with NER proteins, providing a biochemical and genetical basis for these proteins to function in common processes

Up-regulation of mismatch repair genes MSH6, PMS2 and MLH1 parallels development of genetic instability and is linked to tumor aggressiveness and early PSA recurrence in prostate cancer.

Science.gov (United States)

Wilczak, Waldemar; Rashed, Semin; Hube-Magg, Claudia; Kluth, Martina; Simon, Ronald; Büscheck, Franziska; Clauditz, Till Sebastian; Grupp, Katharina; Minner, Sarah; Tsourlakis, Maria Christina; Möller-Koop, Christina; Graefen, Markus; Adam, Meike; Haese, Alexander; Wittmer, Corinna; Sauter, Guido; Izbicki, Jakob Robert; Huland, Hartwig; Schlomm, Thorsten; Steurer, Stefan; Krech, Till; Lebok, Patrick

2017-01-01

DNA mismatch repair (MMR) is integral to the maintenance of genetic stability. We aimed to evaluate the clinical impact of MMR gene expression in prostate cancer. The MMR genes MSH6, MLH1 and PMS2 were analyzed by immunohistochemistry on a tissue microarray containing 11152 prostate cancer specimens. Results were compared with ETS-related gene status and deletions of PTEN, 3p13, 5q21 and 6q15. MSH6, MLH1 and PMS2 expression was detectable in 89.5%, 85.4% and 85.0% of cancers and was particularly strong in cancers with advanced pathological tumor stage (P < 0.0001 each), high Gleason grade (P < 0.0001 each), nodal metastasis (P ≤ 0.0083) and early biochemical recurrence (P < 0.0001). High levels of MMR gene expression paralleled features of genetic instability, such as the number of genomic deletions per cancer; strong expression of all three MMR genes was found in 24%, 29%, 30%, 33% and 42% of cancers with no, one, two, three or four to five deletions (P < 0.0001). The prognostic value of the analyzed MMR genes was largely driven by the subset of cancers lacking ERG fusion (P < 0.0001), while the prognostic impact of MMR gene overexpression was only marginal in ERG-positive cancers. Multivariate analyses suggested an independent prognostic relevance of MMR genes in ERG-negative prostate cancers when compared with prognostic parameters available at the time of initial biopsy. In conclusion, MMR overexpression is common in prostate cancer and is linked to poor outcome as well as features indicating genetic instability. ERG fusion should be analyzed along with MMR gene expression in potential clinical tests. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Methylation Analysis of DNA Mismatch Repair Genes Using DNA Derived from the Peripheral Blood of Patients with Endometrial Cancer: Epimutation in Endometrial Carcinogenesis

Directory of Open Access Journals (Sweden)

Takashi Takeda

2016-10-01

Full Text Available Germline mutation of DNA mismatch repair (MMR genes is a cause of Lynch syndrome. Methylation of MutL homolog 1 (MLH1 and MutS homolog 2 (MSH2 has been detected in peripheral blood cells of patients with colorectal cancer. This methylation is referred to as epimutation. Methylation of these genes has not been studied in an unselected series of endometrial cancer cases. Therefore, we examined methylation of MLH1, MSH2, and MSH6 promoter regions of peripheral blood cells in 206 patients with endometrial cancer using a methylation-specific polymerase chain reaction (MSP. Germline mutation of MMR genes, microsatellite instability (MSI, and immunohistochemistry (IHC were also analyzed in each case with epimutation. MLH1 epimutation was detected in a single patient out of a total of 206 (0.49%—1 out of 58 (1.72% with an onset age of less than 50 years. The patient with MLH1 epimutation showed high level MSI (MSI-H, loss of MLH1 expression and had developed endometrial cancer at 46 years old, complicated with colorectal cancer. No case had epimutation of MSH2 or MSH6. The MLH1 epimutation detected in a patient with endometrial cancer may be a cause of endometrial carcinogenesis. This result indicates that it is important to check epimutation in patients with endometrial cancer without a germline mutation of MMR genes.

Four novel germline mutations in the MLH1 and PMS2 mismatch repair genes in patients with hereditary nonpolyposis colorectal cancer.

Science.gov (United States)

Montazer Haghighi, Mahdi; Radpour, Ramin; Aghajani, Katayoun; Zali, Narges; Molaei, Mahsa; Zali, Mohammad Reza

2009-08-01

Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common cause of early onset hereditary colorectal cancer. In the majority of HNPCC families, microsatellite instability (MSI) and germline mutation in one of the DNA mismatch repair (MMR) genes are found. The entire coding sequence of MMR genes (MLH1, MLH2, MLH6, and PMS2) was analyzed using direct sequencing. Also, tumor tests were done as MSI and immunohistochemistry testing. We were able to find three novel MLH1 and one novel PMS2 germline mutations in three Iranian HNPCC patients. The first was a transversion mutation c.346A>C (T116P) and happened in the highly conserved HATPase-c region of MLH1 protein. The second was a transversion mutation c.736A>T (I246L), which caused an amino acid change of isoleucine to leucine. The third mutation (c.2145,6 delTG) was frameshift and resulted in an immature stop codon in five codons downstream. All of these three mutations were detected in the MLH1 gene. The other mutation was a transition mutation, c.676G>A (G207E), which has been found in exon six of the PMS2 gene and caused an amino acid change of glycine to glutamic acid. MSI assay revealed high instability in microsatellite for two patients and microsatellite stable for one patient. In all patients, an abnormal expression of the MMR proteins in HNPCC was related to the above novel mutations.

Mismatch repair protein deficient endometrioid adenocarcinomas, metastasizing to adrenal gland and lymph nodes: Unusual cases with diagnostic implications

Directory of Open Access Journals (Sweden)

Bharat Rekhi

2015-01-01

Full Text Available Recently, certain endometrial carcinomas have been found to be associated with mismatch repair (MMR protein defects/deficiency. A 39-year-old female presented with cough, decreased appetite and significant weight loss since 2 months. Earlier, she had undergone total abdominal hysterectomy with bilateral salpingo-oophorectomy (TAH-BSO for endometrioid adenocarcinoma. Imaging disclosed an 8 cm-sized adrenal mass that was surgically excised. Histopathology of the adrenal tumor, endocervical tumor, and endometrial biopsy revealed Federation of Gynecology and Obstetrics (FIGO Grade II to III endometrioid adenocarcinoma. By immunohistochemistry, tumor cells were positive for cytokeratin 7, epithelial membrane antigen, PAX8, MLH1 and PMS2 while negative for estrogen receptor (ER, progesterone receptor (PR, MSH2 and MSH6. She underwent adjuvant radiotherapy and chemotherapy. A 34-year-old lady presented with vaginal bleeding since 9 months. She underwent TAH-BSO, reported as FIGO Grade III endometrioid adenocarcinoma. By immunohistochemistry, tumor cells were negative for ER, PR, MLH1, and PMS2 while positive for MSH2 and MSH6. She underwent adjuvant radiotherapy and chemotherapy. However, she developed multiple nodal and pericardial metastases and succumbed to the disease within a year post-diagnosis. Certain high-grade endometrioid adenocarcinomas occurring in younger women are MMR protein deficient and display an aggressive clinical course. Adrenal metastasis in endometrial carcinomas is rare.

The role of the bacterial mismatch repair system in SOS-induced mutagenesis: a theoretical background

International Nuclear Information System (INIS)

Belov, O.V.; Kapralov, M.I.; Chuluunbaatar, O.; Sweilam, N.H.

2012-01-01

A theoretical study is performed of the possible role of the methyl-directed mismatch repair system in the ultraviolet-induced mutagenesis of Escherichia coli bacterial cells. For this purpose, a mathematical model of the bacterial mismatch repair system is developed. Within this model, the key pathways of this type of repair are simulated on the basis of modern experimental data related to its mechanisms. Here we have modelled in detail five main pathways of DNA misincorporation removal with different DNA exonucleases. Using our calculations, we have tested the hypothesis that the bacterial mismatch repair system is responsible for the removal of the nucleotides misincorporated by DNA polymerase V (the UmuD' 2 C complex) during ultraviolet-induced SOS response. For the theoretical analysis of the mutation frequency, we have combined the proposed mathematical approach with the model of SOS-induced mutagenesis in the E.coli bacterial cell developed earlier. Our calculations support the hypothesis that methyl-directed mismatch repair influences the mutagenic effect of ultraviolet radiation

Promoter methylation and expression of MGMT and the DNA mismatch repair genes MLH1, MSH2, MSH6 and PMS2 in paired primary and recurrent glioblastomas.

Science.gov (United States)

Felsberg, Jörg; Thon, Niklas; Eigenbrod, Sabina; Hentschel, Bettina; Sabel, Michael C; Westphal, Manfred; Schackert, Gabriele; Kreth, Friedrich Wilhelm; Pietsch, Torsten; Löffler, Markus; Weller, Michael; Reifenberger, Guido; Tonn, Jörg C

2011-08-01

Epigenetic silencing of the O(6) -methylguanine-DNA methyltransferase (MGMT) gene promoter is associated with prolonged survival in glioblastoma patients treated with temozolomide (TMZ). We investigated whether glioblastoma recurrence is associated with changes in the promoter methylation status and the expression of MGMT and the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2 in pairs of primary and recurrent glioblastomas of 80 patients, including 64 patients treated with radiotherapy and TMZ after the first operation. Among the primary tumors, the MGMT promoter was methylated in 31 patients and unmethylated in 49 patients. In 71 patients (89%), the MGMT promoter methylation status of the primary tumor was retained at recurrence. MGMT promoter methylation, but not MGMT protein expression, was associated with longer progression-free survival, overall survival and postrecurrence survival (PRS). Moreover, PRS was increased under salvage chemotherapy. Investigation of primary and recurrent glioblastomas of 43 patients did not identify promoter methylation in any of the four MMR genes. However, recurrent glioblastomas demonstrated significantly lower MSH2, MSH6 and PMS2 protein expression as detected by immunohistochemistry. In conclusion, reduced expression of MMR proteins, but not changes in MGMT promoter methylation, is characteristic of glioblastomas recurring after the current standards of care. Copyright © 2011 UICC.

Exonuclease 1 and its versatile roles in DNA repair

DEFF Research Database (Denmark)

Keijzers, Guido; Liu, Dekang; Rasmussen, Lene Juel

2016-01-01

Exonuclease 1 (EXO1) is a multifunctional 5' → 3' exonuclease and a DNA structure-specific DNA endonuclease. EXO1 plays roles in DNA replication, DNA mismatch repair (MMR) and DNA double-stranded break repair (DSBR) in lower and higher eukaryotes and contributes to meiosis, immunoglobulin...... maturation, and micro-mediated end-joining in higher eukaryotes. In human cells, EXO1 is also thought to play a role in telomere maintenance. Mutations in the human EXO1 gene correlate with increased susceptibility to some cancers. This review summarizes recent studies on the enzymatic functions...

MSH6- or PMS2-deficiency causes re-replication in DT40 B cells, but it has little effect on immunoglobulin gene conversion or on repair of AID-generated uracils

Science.gov (United States)

Campo, Vanina A.; Patenaude, Anne-Marie; Kaden, Svenja; Horb, Lori; Firka, Daniel; Jiricny, Josef; Di Noia, Javier M.

2013-01-01

The mammalian antibody repertoire is shaped by somatic hypermutation (SHM) and class switch recombination (CSR) of the immunoglobulin (Ig) loci of B lymphocytes. SHM and CSR are triggered by non-canonical, error-prone processing of G/U mismatches generated by activation-induced deaminase (AID). In birds, AID does not trigger SHM, but it triggers Ig gene conversion (GC), a ‘homeologous’ recombination process involving the Ig variable region and proximal pseudogenes. Because recombination fidelity is controlled by the mismatch repair (MMR) system, we investigated whether MMR affects GC in the chicken B cell line DT40. We show here that Msh6−/− and Pms2−/− DT40 cells display cell cycle defects, including genomic re-replication. However, although IgVλ GC tracts in MMR-deficient cells were slightly longer than in normal cells, Ig GC frequency, donor choice or the number of mutations per sequence remained unaltered. The finding that the avian MMR system, unlike that of mammals, does not seem to contribute towards the processing of G/U mismatches in vitro could explain why MMR is unable to initiate Ig GC in this species, despite initiating SHM and CSR in mammalian cells. Moreover, as MMR does not counteract or govern Ig GC, we report a rare example of ‘homeologous’ recombination insensitive to MMR. PMID:23314153

Explosive mutation accumulation triggered by heterozygous human Pol ε proofreading-deficiency is driven by suppression of mismatch repair

Science.gov (United States)

Campbell, Brittany B; Ungerleider, Nathan; Light, Nicholas; Wu, Tong; LeCompte, Kimberly G; Goksenin, A Yasemin; Bunnell, Bruce A; Tabori, Uri; Shlien, Adam

2018-01-01

Tumors defective for DNA polymerase (Pol) ε proofreading have the highest tumor mutation burden identified. A major unanswered question is whether loss of Pol ε proofreading by itself is sufficient to drive this mutagenesis, or whether additional factors are necessary. To address this, we used a combination of next generation sequencing and in vitro biochemistry on human cell lines engineered to have defects in Pol ε proofreading and mismatch repair. Absent mismatch repair, monoallelic Pol ε proofreading deficiency caused a rapid increase in a unique mutation signature, similar to that observed in tumors from patients with biallelic mismatch repair deficiency and heterozygous Pol ε mutations. Restoring mismatch repair was sufficient to suppress the explosive mutation accumulation. These results strongly suggest that concomitant suppression of mismatch repair, a hallmark of colorectal and other aggressive cancers, is a critical force for driving the explosive mutagenesis seen in tumors expressing exonuclease-deficient Pol ε. PMID:29488881

SERIES: Genomic instability in cancer Balancing repair and tolerance of DNA damage caused by alkylating agents

OpenAIRE

Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D

2012-01-01

Alkylating agents comprise a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER), and mismatch repair (MMR) respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial fo...

GLI1 interferes with the DNA mismatch repair system in pancreatic cancer through BHLHE41-mediated suppression of MLH1.

Science.gov (United States)

Inaguma, Shingo; Riku, Miho; Hashimoto, Mitsuyoshi; Murakami, Hideki; Saga, Shinsuke; Ikeda, Hiroshi; Kasai, Kenji

2013-12-15

The mismatch repair (MMR) system is indispensable for the fidelity of DNA replication, the impairment of which predisposes to the development and progression of many types of cancers. To date, GLI1 transcription factor, a key molecule of the Hedgehog signaling pathway, has been shown to regulate the expression of several genes crucial for a variety of cancer cell properties in many types of cancers, including pancreatic ductal adenocarcinoma (PDAC), but whether GLI1 could control the MMR system was not known. Here, we showed that GLI1 and GLI2 indirectly suppressed the expression of MLH1 in PDAC cells. Through GLI1 target gene screening, we found that GLI1 and GLI2 activated the expression of a basic helix-loop-helix type suppressor BHLHE41/DEC2/SHARP1 through a GLI-binding site in the promoter. Consistent with a previous report that BHLHE41 suppresses the MLH1 promoter activity, we found that the activation of GLI1 led to the BHLHE41-dependent suppression of MLH1, and a double knockdown of GLI1 and GLI2 conversely increased the MLH1 protein in PDAC cells. Using TALEN-based modification of the MLH1 gene, we further showed that GLI1 expression was indeed associated with an increased tolerance to a methylating agent, methylnitrosourea cooperatively with a lower copy number status of MLH1. Finally, GLI1 expression was immunohistochemically related positively with BHLHE41 and inversely with MLH1 in PDAC cells and precancerous lesions of the pancreas. On the basis of these results, we propose that GLI1 depresses the MMR activity and might contribute to the development and progression of PDAC. ©2013 AACR.

Nuclear translocation contributes to regulation of DNA excision repair activities

DEFF Research Database (Denmark)

Knudsen, Nina Østergaard; Andersen, Sofie Dabros; Lützen, Anne

2009-01-01

for regulation of nuclear import that is necessary for proper localization of the repair proteins. This review summarizes the current knowledge on nuclear import mechanisms of DNA excision repair proteins and provides a model that categorizes the import by different mechanisms, including classical nuclear import......DNA mutations are circumvented by dedicated specialized excision repair systems, such as the base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR) pathways. Although the individual repair pathways have distinct roles in suppressing changes in the nuclear DNA......, it is evident that proteins from the different DNA repair pathways interact [Y. Wang, D. Cortez, P. Yazdi, N. Neff, S.J. Elledge, J. Qin, BASC, a super complex of BRCA1-associated proteins involved in the recognition and repair of aberrant DNA structures, Genes Dev. 14 (2000) 927-939; M. Christmann, M...

Rhabdomyosarcoma in patients with constitutional mismatch-repair-deficiency syndrome.

Science.gov (United States)

Kratz, C P; Holter, S; Etzler, J; Lauten, M; Pollett, A; Niemeyer, C M; Gallinger, S; Wimmer, K

2009-06-01

Biallelic germline mutations in the mismatch repair genes MLH1, MSH2, MSH6 or PMS2 cause a recessive childhood cancer syndrome characterised by early-onset malignancies and signs reminiscent of neurofibromatosis type 1 (NF1). Alluding to the underlying genetic defect, we refer to this syndrome as constitutional mismatch repair-deficiency (CMMR-D) syndrome. The tumour spectrum of CMMR-D syndrome includes haematological neoplasias, brain tumours and Lynch syndrome-associated tumours. Other tumours, such as neuroblastoma, Wilm tumour, ovarian neuroectodermal tumour or infantile myofibromatosis, have so far been found only in individual cases. We analysed two consanguineous families that had members with suspected CMMR-D syndrome who developed rhabdomyosarcoma among other neoplasias. In the first family, we identified a pathogenic PMS2 mutation for which the affected patient was homozygous. In family 2, immunohistochemistry analysis showed isolated loss of PMS2 expression in all tumours in the affected patients, including rhabdomyosarcoma itself and the surrounding normal tissue. Together with the family history and microsatellite instability observed in one tumour this strongly suggests an underlying PMS2 alteration in family 2 also. Together, these two new cases show that rhabdomyosarcoma and possibly other embryonic tumours, such as neuroblastoma and Wilm tumour, belong to the tumour spectrum of CMMR-D syndrome. Given the clinical overlap of CMMR-D syndrome with NF1, we suggest careful examination of the family history in patients with embryonic tumours and signs of NF1 as well as analysis of the tumours for loss of one of the mismatch repair genes and microsatellite instability. Subsequent mutation analysis will lead to a definitive diagnosis of the underlying disorder.

Human Postmeiotic Segregation 2 Exhibits Biased Repair at Tetranucleotide Microsatellite Sequences

OpenAIRE

Shah, Sandeep N.; Eckert, Kristin A.

2009-01-01

The mismatch repair (MMR) system plays a major role in removing DNA polymerization errors, and loss of this pathway results in hereditary cancers characterized by microsatellite instability. We investigated microsatellite stability during DNA replication within human postmeiotic segregation 2 (hPMS2)–deficient and proficient human lymphoblastoid cell lines. Using a shuttle vector assay, we measured mutation rates at reporter cassettes containing defined mononucleotide, dinucleotide, and tetra...

Somatosensory mismatch response in young and elderly adults

Directory of Open Access Journals (Sweden)

Juho M. Strömmer

2014-10-01

Full Text Available Aging is associated with cognitive decline and alterations in early perceptual processes. Studies in the auditory and visual modalities have shown that the mismatch negativity (or the mismatch response, MMR, an event-related potential (ERP elicited by a deviant stimulus in a background of homogenous events, diminishes with aging and cognitive decline. However, the effects of aging on the somatosensory MMR are not known. In the current study, we recorded ERPs to electrical pulses to different fingers of the left hand in a passive oddball experiment in young (22–36 years and elderly (66–95 years adults engaged in a visual task. The MMR was found to deviants as compared to standards at two latency ranges: 180–220 ms and 250–290 ms post-stimulus onset. At 180–220 ms, within the young, the MMR was found at medial electrode sites, whereas aged did not show any amplitude difference between the stimulus types at the same latency range. At 250–290 ms, the MMR was evident with attenuated amplitude and narrowed scalp distribution among aged (Fz compared to young (fronto-centrally and lateral parietal sites. Hence, the results reveal that the somatosensory change detection mechanism is altered in aging. The somatosensory MMR can be used as a reliable measure of age-related changes in sensory-cognitive functions.

Constitutional mismatch repair deficiency syndrome: clinical description in a French cohort.

Science.gov (United States)

Lavoine, N; Colas, C; Muleris, M; Bodo, S; Duval, A; Entz-Werle, N; Coulet, F; Cabaret, O; Andreiuolo, F; Charpy, C; Sebille, G; Wang, Q; Lejeune, S; Buisine, M P; Leroux, D; Couillault, G; Leverger, G; Fricker, J P; Guimbaud, R; Mathieu-Dramard, M; Jedraszak, G; Cohen-Hagenauer, O; Guerrini-Rousseau, L; Bourdeaut, F; Grill, J; Caron, O; Baert-Dusermont, S; Tinat, J; Bougeard, G; Frébourg, T; Brugières, L

2015-11-01

Constitutional mismatch repair deficiency (CMMRD) syndrome is a childhood cancer predisposition syndrome involving biallelic germline mutations of MMR genes, poorly recognised by clinicians so far. Retrospective review of all 31 patients with CMMRD diagnosed in French genetics laboratories in order to describe the characteristics, treatment and outcome of the malignancies and biological diagnostic data. 67 tumours were diagnosed in 31 patients, 25 (37%) Lynch syndrome-associated malignancies, 22 (33%) brain tumours, 17 (25%) haematological malignancies and 3 (5%) sarcomas. The median age of onset of the first tumour was 6.9 years (1.2-33.5). Overall, 22 patients died, 9 (41%) due to the primary tumour. Median survival after the diagnosis of the primary tumour was 27 months (0.26-213.2). Failure rate seemed to be higher than expected especially for T-cell non-Hodgkin's lymphoma (progression/relapse in 6/12 patients). A familial history of Lynch syndrome was identified in 6/23 families, and consanguinity in 9/23 families. PMS2 mutations (n=18) were more frequent than other mutations (MSH6 (n=6), MLH1 (n=4) and MSH2 (n=3)). In conclusion, this unselected series of patients confirms the extreme severity of this syndrome with a high mortality rate mostly related to multiple childhood cancers, and highlights the need for its early detection in order to adapt treatment and surveillance. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

DNA mismatch repair and its many roles in eukaryotic cells

DEFF Research Database (Denmark)

Liu, Dekang; Keijzers, Guido; Rasmussen, Lene Juel

2017-01-01

in the clinic, and as a biomarker of cancer susceptibility in animal model systems. Prokaryotic MMR is well-characterized at the molecular and mechanistic level; however, MMR is considerably more complex in eukaryotic cells than in prokaryotic cells, and in recent years, it has become evident that MMR plays...... novel roles in eukaryotic cells, several of which are not yet well-defined or understood. Many MMR-deficient human cancer cells lack mutations in known human MMR genes, which strongly suggests that essential eukaryotic MMR components/cofactors remain unidentified and uncharacterized. Furthermore......, the mechanism by which the eukaryotic MMR machinery discriminates between the parental (template) and the daughter (nascent) DNA strand is incompletely understood and how cells choose between the EXO1-dependent and the EXO1–independent subpathways of MMR is not known. This review summarizes recent literature...

Review: Clinical aspects of hereditary DNA Mismatch repair gene mutations

NARCIS (Netherlands)

Sijmons, Rolf H.; Hofstra, Robert M. W.

Inherited mutations of the DNA Mismatch repair genes MLH1, MSH2, MSH6 and PMS2 can result in two hereditary tumor syndromes: the adult-onset autosomal dominant Lynch syndrome, previously referred to as Hereditary Non-Polyposis Colorectal Cancer (HNPCC) and the childhood-onset autosomal recessive

MSH3 mismatch repair protein regulates sensitivity to cytotoxic drugs and a histone deacetylase inhibitor in human colon carcinoma cells.

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Jae Myung Park

Full Text Available MSH3 is a DNA mismatch repair (MMR gene that undergoes frequent somatic mutation in colorectal cancers (CRCs with MMR deficiency. MSH3, together with MSH2, forms the MutSβ heteroduplex that interacts with interstrand cross-links induced by drugs such as cisplatin. To date, the impact of MSH3 on chemosensitivity is unknown.We utilized isogenic HCT116 (MLH1-/MSH3- cells where MLH1 is restored by transfer of chromosome 3 (HCT116+ch3 and also MSH3 by chromosome 5 (HCT116+3+5. We generated HCT116+3+5, SW480 (MLH1+/MSH3+ and SW48 (MLH1-/MSH3+ cells with shRNA knockdown of MSH3. Cells were treated with 5-fluorouracil (5-FU, SN-38, oxaliplatin, or the histone deacetylase (HDAC inhibitor PCI-24781 and cell viability, clonogenic survival, DNA damage and apoptosis were analyzed.MSH3-deficient vs proficient CRC cells showed increased sensitivity to the irinotecan metabolite SN-38 and to oxaliplatin, but not 5-FU, as shown in assays for apoptosis and clonogenic survival. In contrast, suppression of MLH1 attenuated the cytotoxic effect of 5-FU, but did not alter sensitivity to SN-38 or oxaliplatin. The impact of MSH3 knockdown on chemosensitivity to SN-38 and oxaliplatin was maintained independent of MLH1 status. In MSH3-deficient vs proficient cells, SN-38 and oxaliplatin induced higher levels of phosphorylated histone H2AX and Chk2, and similar results were found in MLH1-proficient SW480 cells. MSH3-deficient vs proficient cells showed increased 53BP1 nuclear foci after irradiation, suggesting that MSH3 can regulate DNA double strand break (DSB repair. We then utilized PCI-24781 that interferes with homologous recombination (HR indicated by a reduction in Rad51 expression. The addition of PCI-24781 to oxaliplatin enhanced cytotoxicity to a greater extent compared to either drug alone.MSH3 status can regulate the DNA damage response and extent of apoptosis induced by chemotherapy. The ability of MSH3 to regulate chemosensitivity was independent of MLH1

Curcumin chemosensitizes 5-fluorouracil resistant MMR-deficient human colon cancer cells in high density cultures.

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Mehdi Shakibaei

Full Text Available OBJECTIVE: Treatment of colorectal cancer (CRC remains a clinical challenge, as more than 15% of patients are resistant to 5-Fluorouracil (5-FU-based chemotherapeutic regimens, and tumor recurrence rates can be as high as 50-60%. Cancer stem cells (CSC are capable of surviving conventional chemotherapies that permits regeneration of original tumors. Therefore, we investigated the effectiveness of 5-FU and plant polyphenol (curcumin in context of DNA mismatch repair (MMR status and CSC activity in 3D cultures of CRC cells. METHODS: High density 3D cultures of CRC cell lines HCT116, HCT116+ch3 (complemented with chromosome 3 and their corresponding isogenic 5-FU-chemo-resistant derivative clones (HCT116R, HCT116+ch3R were treated with 5-FU either without or with curcumin in time- and dose-dependent assays. RESULTS: Pre-treatment with curcumin significantly enhanced the effect of 5-FU on HCT116R and HCR116+ch3R cells, in contrast to 5-FU alone as evidenced by increased disintegration of colonospheres, enhanced apoptosis and by inhibiting their growth. Curcumin and/or 5-FU strongly affected MMR-deficient CRC cells in high density cultures, however MMR-proficient CRC cells were more sensitive. These effects of curcumin in enhancing chemosensitivity to 5-FU were further supported by its ability to effectively suppress CSC pools as evidenced by decreased number of CSC marker positive cells, highlighting the suitability of this 3D culture model for evaluating CSC marker expression in a close to vivo setting. CONCLUSION: Our results illustrate novel and previously unrecognized effects of curcumin in enhancing chemosensitization to 5-FU-based chemotherapy on DNA MMR-deficient and their chemo-resistant counterparts by targeting the CSC sub-population. (246 words in abstract.

Curcumin chemosensitizes 5-fluorouracil resistant MMR-deficient human colon cancer cells in high density cultures.

Science.gov (United States)

Shakibaei, Mehdi; Buhrmann, Constanze; Kraehe, Patricia; Shayan, Parviz; Lueders, Cora; Goel, Ajay

2014-01-01

Treatment of colorectal cancer (CRC) remains a clinical challenge, as more than 15% of patients are resistant to 5-Fluorouracil (5-FU)-based chemotherapeutic regimens, and tumor recurrence rates can be as high as 50-60%. Cancer stem cells (CSC) are capable of surviving conventional chemotherapies that permits regeneration of original tumors. Therefore, we investigated the effectiveness of 5-FU and plant polyphenol (curcumin) in context of DNA mismatch repair (MMR) status and CSC activity in 3D cultures of CRC cells. High density 3D cultures of CRC cell lines HCT116, HCT116+ch3 (complemented with chromosome 3) and their corresponding isogenic 5-FU-chemo-resistant derivative clones (HCT116R, HCT116+ch3R) were treated with 5-FU either without or with curcumin in time- and dose-dependent assays. Pre-treatment with curcumin significantly enhanced the effect of 5-FU on HCT116R and HCR116+ch3R cells, in contrast to 5-FU alone as evidenced by increased disintegration of colonospheres, enhanced apoptosis and by inhibiting their growth. Curcumin and/or 5-FU strongly affected MMR-deficient CRC cells in high density cultures, however MMR-proficient CRC cells were more sensitive. These effects of curcumin in enhancing chemosensitivity to 5-FU were further supported by its ability to effectively suppress CSC pools as evidenced by decreased number of CSC marker positive cells, highlighting the suitability of this 3D culture model for evaluating CSC marker expression in a close to vivo setting. Our results illustrate novel and previously unrecognized effects of curcumin in enhancing chemosensitization to 5-FU-based chemotherapy on DNA MMR-deficient and their chemo-resistant counterparts by targeting the CSC sub-population. (246 words in abstract).

Prospective evaluation of fluorouracil chemotherapy based on the genetic makeup of colorectal cancer

OpenAIRE

Carethers, J M

2006-01-01

Evaluation of 5‐fluorouracil chemotherapy and survival, based on mismatch repair (MMR) status, indicates that patients with MMR proficient colorectal tumours benefit from 5‐fluorouracil treatment while patients with MMR deficient tumours do not

Alteration of cellular radiation response as a consequence of defective DNA mismatch repair

International Nuclear Information System (INIS)

Weese, Theodore L. de; Bucci, Jennifer M.; Larrier, Nicole A.; Cutler, Richard G.; Riele, Hein te; Nelson, William G.

1997-01-01

Purpose/Objective: A number of genes have been implicated in the response of mammalian cells to ionizing radiation. Among these include the genes P53 and P21. Disruption of these genes can alter the predicted cellular behavior following radiation-induced DNA damage. Similarly, cells defective in mismatch repair are known to be tolerant to the lethal effects of alkylating agents. We hypothesized that mammalian cells which are defective in mismatch repair and tolerant to alkylating DNA damage might also be tolerant to the effects of oxidative DNA damage inflicted by ionizing radiation. Materials and Methods: Mouse embryonic stem cells homozygous for disrupted Msh2 alleles (Msh2-/-), heterozygous for a disrupted Msh2 allele (Msh2+/-) or intact cells (Msh2+/+) were exposed to both acute dose (1 Gy/min) and low dose rate (LDR) radiation (0.004 Gy/min) and cell survival was determined by clonogenic assay. Apoptosis induced by LDR was assessed by a terminal transferase assay. Immunoblot analysis was performed in order to evaluate induction of the polypeptides p53 and p21. Another measure of radiation damage tolerance may be accumulation of oxidative DNA species. Therefore, we monitored levels of 8-hydroxyguanine (8-OHG) and 8-hydroxyadenine (8-OHA) by gas chromatography - mass spectrometry with selected ion monitoring (GC-MS/SIM). Results: Cells containing either one or two disrupted Msh2 alleles (Msh2+/-, Msh2-/-) were found to be less sensitive to LDR than cells containing a complete complement of Msh2 alleles (Msh2+/+). Interestingly, all three cell lines had a nearly identical radiosensitivity to acute dose ionizing radiation despite differences in mismatch repair capacity. Apoptosis after LDR also varied between cells, with the Msh2+/+ cells exhibiting higher levels of apoptosis as compared to either the Msh2+/- or Msh2-/- cell lines. In addition, GC-MS/SIM revealed the Msh2+/- and Msh2-/- cell lines to have an approximately ten fold greater accumulation of the

Frequent mismatch-repair defects link prostate cancer to Lynch syndrome

DEFF Research Database (Denmark)

Dominguez-Valentin, Mev; Joost, Patrick; Therkildsen, Christina

2016-01-01

were high-grade tumors with Gleason scores 8-10. Prostate cancer was associated with mutations in MSH2, MLH1 and MSH6 with loss of the respective mismatch repair protein in 69 % of the tumors, though a MSI-high phenotype was restricted to 13 % of the tumors. The cumulative risk of prostate cancer...

Developmental changes in mismatch responses to mandarin consonants and lexical tones from early to middle childhood.

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Huei-Mei Liu

Full Text Available The purpose of this study was to use mismatch responses (MMRs to explore the dynamic changes of Mandarin speech perception abilities from early to middle childhood. Twenty preschoolers, 18 school-aged children, and 26 adults participated in this study. Two sets of synthesized speech stimuli varying in Mandarin consonant (alveolo-palatal affricate vs. fricative and lexical tone features (rising vs. contour tone were used to examine the developmental course of speech perception abilities. The results indicated that only the adult group demonstrated typical early mismatch negativity (MMN responses, suggesting that the ability to discriminate specific speech cues in Mandarin consonant and lexical tone is a continuing process in preschool- and school-aged children. Additionally, distinct MMR patterns provided evidence indicating diverse developmental courses to different speech characteristics. By incorporating data from the two speech conditions, we propose using MMR profiles consisting of mismatch negativity (MMN, positive mismatch response (p-MMR, and late discriminative negativity (LDN as possible brain indices to investigate speech perception development.

Germline PMS2 mutation screened by mismatch repair protein immunohistochemistry of colorectal cancer in Japan.

Science.gov (United States)

Sugano, Kokichi; Nakajima, Takeshi; Sekine, Shigeki; Taniguchi, Hirokazu; Saito, Shinya; Takahashi, Masahiro; Ushiama, Mineko; Sakamoto, Hiromi; Yoshida, Teruhiko

2016-11-01

Germline PMS2 gene mutations were detected by RT-PCR/direct sequencing of total RNA extracted from puromycin-treated peripheral blood lymphocytes (PBL) and multiplex ligation-dependent probe amplification (MLPA) analyses of Japanese patients with colorectal cancer (CRC) fulfilling either the revised Bethesda Guidelines or being an age at disease onset of younger than 70 years, and screened by mismatch repair protein immunohistochemistry of formalin-fixed paraffin embedded sections. Of the 501 subjects examined, 7 (1.40%) showed the downregulated expression of the PMS2 protein alone and were referred to the genetic counseling clinic. Germline PMS2 mutations were detected in 6 (85.7%), including 3 nonsense and 1 frameshift mutations by RT-PCR/direct sequencing and 2 genomic deletions by MLPA. No mutations were identified in the other MMR genes (i.e. MSH2, MLH1 and MSH6). The prevalence of the downregulated expression of the PMS2 protein alone was 1.40% among the subjects examined and IHC results predicted the presence of PMS2 germline mutations. RT-PCR from puromycin-treated PBL and MLPA may be employed as the first screening step to detect PMS2 mutations without pseudogene interference, followed by the long-range PCR/nested PCR validation using genomic DNA. © 2016 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Mismatch repair deficiency in colorectal cancer patients in a low ...

African Journals Online (AJOL)

2013-02-06

Feb 6, 2013 ... This is 10% of the rate reported in First-World countries. In high-incidence areas, the rate of abnormal mismatch repair gene expression in colorectal cancers is 2 - 7%. Objectives. The aim of this study was to determine the prevalence of hMLH1- and hMSH2-deficient colorectal cancer in the. Northern Cape.

Complex DNA repair pathways as possible therapeutic targets to overcome temozolomide resistance in glioblastoma

International Nuclear Information System (INIS)

Yoshimoto, Koji; Mizoguchi, Masahiro; Hata, Nobuhiro; Murata, Hideki; Hatae, Ryusuke; Amano, Toshiyuki; Nakamizo, Akira; Sasaki, Tomio

2012-01-01

Many conventional chemotherapeutic drugs exert their cytotoxic function by inducing DNA damage in the tumor cell. Therefore, a cell-inherent DNA repair pathway, which reverses the DNA-damaging effect of the cytotoxic drugs, can mediate therapeutic resistance to chemotherapy. The monofunctional DNA-alkylating agent temozolomide (TMZ) is a commonly used chemotherapeutic drug and the gold standard treatment for glioblastoma (GBM). Although the activity of DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) has been described as the main modulator to determine the sensitivity of GBM to TMZ, a subset of GBM does not respond despite MGMT inactivation, suggesting that another DNA repair mechanism may also modulate the tolerance to TMZ. Considerable interest has focused on MGMT, mismatch repair (MMR), and the base excision repair (BER) pathway in the mechanism of mediating TMZ resistance, but emerging roles for the DNA strand-break repair pathway have been demonstrated. In the first part of this review article, we briefly review the significant role of MGMT, MMR, and the BER pathway in the tolerance to TMZ; in the last part, we review the recent publications that demonstrate possible roles of DNA strand-break repair pathways, such as single-strand break repair and double-strand break repair, as well as the Fanconi anemia pathway in the repair process after alkylating agent-based therapy. It is possible that all of these repair pathways have a potential to modulate the sensitivity to TMZ and aid in overcoming the therapeutic resistance in the clinic.

Complex DNA repair pathways as possible therapeutic targets to overcome temozolomide resistance in glioblastoma

Energy Technology Data Exchange (ETDEWEB)

Yoshimoto, Koji; Mizoguchi, Masahiro; Hata, Nobuhiro; Murata, Hideki; Hatae, Ryusuke; Amano, Toshiyuki; Nakamizo, Akira; Sasaki, Tomio, E-mail: kyoshimo@ns.med.kyushu-u.ac.jp [Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan)

2012-12-05

Many conventional chemotherapeutic drugs exert their cytotoxic function by inducing DNA damage in the tumor cell. Therefore, a cell-inherent DNA repair pathway, which reverses the DNA-damaging effect of the cytotoxic drugs, can mediate therapeutic resistance to chemotherapy. The monofunctional DNA-alkylating agent temozolomide (TMZ) is a commonly used chemotherapeutic drug and the gold standard treatment for glioblastoma (GBM). Although the activity of DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) has been described as the main modulator to determine the sensitivity of GBM to TMZ, a subset of GBM does not respond despite MGMT inactivation, suggesting that another DNA repair mechanism may also modulate the tolerance to TMZ. Considerable interest has focused on MGMT, mismatch repair (MMR), and the base excision repair (BER) pathway in the mechanism of mediating TMZ resistance, but emerging roles for the DNA strand-break repair pathway have been demonstrated. In the first part of this review article, we briefly review the significant role of MGMT, MMR, and the BER pathway in the tolerance to TMZ; in the last part, we review the recent publications that demonstrate possible roles of DNA strand-break repair pathways, such as single-strand break repair and double-strand break repair, as well as the Fanconi anemia pathway in the repair process after alkylating agent-based therapy. It is possible that all of these repair pathways have a potential to modulate the sensitivity to TMZ and aid in overcoming the therapeutic resistance in the clinic.

Distinct Gene Expression Signatures in Lynch Syndrome and Familial Colorectal Cancer Type X

DEFF Research Database (Denmark)

Valentin, Mev; Therkildsen, Christina; Veerla, Srinivas

2013-01-01

Heredity is estimated to cause at least 20% of colorectal cancer. The hereditary nonpolyposis colorectal cancer subset is divided into Lynch syndrome and familial colorectal cancer type X (FCCTX) based on presence of mismatch repair (MMR) gene defects.......Heredity is estimated to cause at least 20% of colorectal cancer. The hereditary nonpolyposis colorectal cancer subset is divided into Lynch syndrome and familial colorectal cancer type X (FCCTX) based on presence of mismatch repair (MMR) gene defects....

Interaction of proliferating cell nuclear antigen with PMS2 is required for MutLα activation and function in mismatch repair.

Science.gov (United States)

Genschel, Jochen; Kadyrova, Lyudmila Y; Iyer, Ravi R; Dahal, Basanta K; Kadyrov, Farid A; Modrich, Paul

2017-05-09

Eukaryotic MutLα (mammalian MLH1-PMS2 heterodimer; MLH1-PMS1 in yeast) functions in early steps of mismatch repair as a latent endonuclease that requires a mismatch, MutSα/β, and DNA-loaded proliferating cell nuclear antigen (PCNA) for activation. We show here that human PCNA and MutLα interact specifically but weakly in solution to form a complex of approximately 1:1 stoichiometry that depends on PCNA interaction with the C-terminal endonuclease domain of the MutLα PMS2 subunit. Amino acid substitution mutations within a PMS2 C-terminal 721 QRLIAP motif attenuate or abolish human MutLα interaction with PCNA, as well as PCNA-dependent activation of MutLα endonuclease, PCNA- and DNA-dependent activation of MutLα ATPase, and MutLα function in in vitro mismatch repair. Amino acid substitution mutations within the corresponding yeast PMS1 motif ( 723 QKLIIP) reduce or abolish mismatch repair in vivo. Coupling of a weak allele within this motif ( 723 AKLIIP) with an exo1 Δ null mutation, which individually confer only weak mutator phenotypes, inactivates mismatch repair in the yeast cell.

Reflex test reminders in required cancer synoptic templates decrease order entry error: An analysis of mismatch repair immunohistochemical orders to screen for Lynch syndrome.

Science.gov (United States)

Kilgore, Mark R; McIlwain, Carrie A; Schmidt, Rodney A; Norquist, Barbara M; Swisher, Elizabeth M; Garcia, Rochelle L; Rendi, Mara H

2016-01-01

Endometrial carcinoma (EC) is the most common extracolonic malignant neoplasm associated with Lynch syndrome (LS). LS is caused by autosomal dominant germline mutations in DNA mismatch repair (MMR) genes. Screening for LS in EC is often evaluated by loss of immunohistochemical (IHC) expression of DNA MMR enzymes MLH1, MSH2, MSH6, and PMS2 (MMR IHC). In July 2013, our clinicians asked that we screen all EC in patients ≤60 for loss of MMR IHC expression. Despite this policy, several cases were not screened or screening was delayed. We implemented an informatics-based approach to ensure that all women who met criteria would have timely screening. Reports are created in PowerPath (Sunquest Information Systems, Tucson, AZ) with custom synoptic templates. We implemented an algorithm on March 6, 2014 requiring pathologists to address MMR IHC in patients ≤60 with EC before sign out (S/O). Pathologists must answer these questions: is patient ≤60 (yes/no), if yes, follow-up questions (IHC done previously, ordered with addendum to follow, results included in report, N/A, or not ordered), if not ordered, one must explain. We analyzed cases from July 18, 2013 to August 31, 2016 preimplementation (PreImp) and postimplementation (PostImp) that met criteria. Data analysis was performed using the standard data package included with GraphPad Prism ® 7.00 (GraphPad Software, Inc., La Jolla, CA, USA). There were 147 patients who met criteria (29 PreImp and 118 PostImp). IHC was ordered in a more complete and timely fashion PostImp than PreImp. PreImp, 4/29 (13.8%) cases did not get any IHC, but PostImp, only 4/118 (3.39%) were missed ( P = 0.0448). Of cases with IHC ordered, 60.0% (15/25) were ordered before or at S/O PreImp versus 91.2% (104/114) PostImp ( P = 0.0004). Relative to day of S/O, the mean days of order delay were longer and more variable PreImp versus PostImp (12.9 ± 40.7 vs. -0.660 ± 1.15; P = 0.0227), with the average being before S/O PostImp. This algorithm

Reflex test reminders in required cancer synoptic templates decrease order entry error: An analysis of mismatch repair immunohistochemical orders to screen for Lynch syndrome

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Mark R Kilgore

2016-01-01

Full Text Available Background: Endometrial carcinoma (EC is the most common extracolonic malignant neoplasm associated with Lynch syndrome (LS. LS is caused by autosomal dominant germline mutations in DNA mismatch repair (MMR genes. Screening for LS in EC is often evaluated by loss of immunohistochemical (IHC expression of DNA MMR enzymes MLH1, MSH2, MSH6, and PMS2 (MMR IHC. In July 2013, our clinicians asked that we screen all EC in patients ≤60 for loss of MMR IHC expression. Despite this policy, several cases were not screened or screening was delayed. We implemented an informatics-based approach to ensure that all women who met criteria would have timely screening. Subjects and Methods: Reports are created in PowerPath (Sunquest Information Systems, Tucson, AZ with custom synoptic templates. We implemented an algorithm on March 6, 2014 requiring pathologists to address MMR IHC in patients ≤60 with EC before sign out (S/O. Pathologists must answer these questions: is patient ≤60 (yes/no, if yes, follow-up questions (IHC done previously, ordered with addendum to follow, results included in report, N/A, or not ordered, if not ordered, one must explain. We analyzed cases from July 18, 2013 to August 31, 2016 preimplementation (PreImp and postimplementation (PostImp that met criteria. Data analysis was performed using the standard data package included with GraphPad Prism® 7.00 (GraphPad Software, Inc., La Jolla, CA, USA. Results: There were 147 patients who met criteria (29 PreImp and 118 PostImp. IHC was ordered in a more complete and timely fashion PostImp than PreImp. PreImp, 4/29 (13.8% cases did not get any IHC, but PostImp, only 4/118 (3.39% were missed (P = 0.0448. Of cases with IHC ordered, 60.0% (15/25 were ordered before or at S/O PreImp versus 91.2% (104/114 PostImp (P = 0.0004. Relative to day of S/O, the mean days of order delay were longer and more variable PreImp versus PostImp (12.9 ± 40.7 vs. -0.660 ± 1.15; P = 0.0227, with the average

Balancing repair and tolerance of DNA damage caused by alkylating agents.

Science.gov (United States)

Fu, Dragony; Calvo, Jennifer A; Samson, Leona D

2012-01-12

Alkylating agents constitute a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER) and mismatch repair (MMR), respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for a favourable response of an organism to alkylating agents. Furthermore, the response of an individual to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity.

Screening of the DNA mismatch repair genes MLH1, MSH2 and MSH6 in a Greek cohort of Lynch syndrome suspected families

International Nuclear Information System (INIS)

Thodi, Georgia; Fountzilas, George; Yannoukakos, Drakoulis; Fostira, Florentia; Sandaltzopoulos, Raphael; Nasioulas, George; Grivas, Anastasios; Boukovinas, Ioannis; Mylonaki, Maria; Panopoulos, Christos; Magic, Mirjana Brankovic

2010-01-01

Germline mutations in the DNA mismatch repair genes predispose to Lynch syndrome, thus conferring a high relative risk of colorectal and endometrial cancer. The MLH1, MSH2 and MSH6 mutational spectrum reported so far involves minor alterations scattered throughout their coding regions as well as large genomic rearrangements. Therefore, a combination of complete sequencing and a specialized technique for the detection of genomic rearrangements should be conducted during a proper DNA-testing procedure. Our main goal was to successfully identify Lynch syndrome families and determine the spectrum of MLH1, MSH2 and MSH6 mutations in Greek Lynch families in order to develop an efficient screening protocol for the Greek colorectal cancer patients' cohort. Forty-two samples from twenty-four families, out of which twenty two of Greek, one of Cypriot and one of Serbian origin, were screened for the presence of germline mutations in the major mismatch repair genes through direct sequencing and MLPA. Families were selected upon Amsterdam criteria or revised Bethesda guidelines. Ten deleterious alterations were detected in twelve out of the twenty-four families subjected to genetic testing, thus our detection rate is 50%. Four of the pathogenic point mutations, namely two nonsense, one missense and one splice site change, are novel, whereas the detected genomic deletion encompassing exon 6 of the MLH1 gene has been described repeatedly in the LOVD database. The average age of onset for the development of both colorectal and endometrial cancer among mutation positive families is 43.2 years. The mutational spectrum of the MMR genes investigated as it has been shaped by our analysis is quite heterogeneous without any strong indication for the presence of a founder effect

DNA mismatch repair proteins MLH1 and PMS2 can be imported to the nucleus by a classical nuclear import pathway.

Science.gov (United States)

de Barros, Andrea C; Takeda, Agnes A S; Dreyer, Thiago R; Velazquez-Campoy, Adrian; Kobe, Boštjan; Fontes, Marcos R M

2018-03-01

MLH1 and PMS2 proteins form the MutLα heterodimer, which plays a major role in DNA mismatch repair (MMR) in humans. Mutations in MMR-related proteins are associated with cancer, especially with colon cancer. The N-terminal region of MutLα comprises the N-termini of PMS2 and MLH1 and, similarly, the C-terminal region of MutLα is composed by the C-termini of PMS2 and MLH1, and the two are connected by linker region. The nuclear localization sequences (NLSs) necessary for the nuclear transport of the two proteins are found in this linker region. However, the exact NLS sequences have been controversial, with different sequences reported, particularly for MLH1. The individual components are not imported efficiently, presumably due to their C-termini masking their NLSs. In order to gain insights into the nuclear transport of these proteins, we solved the crystal structures of importin-α bound to peptides corresponding to the supposed NLSs of MLH1 and PMS2 and performed isothermal titration calorimetry to study their binding affinities. Both putative MLH1 and PMS2 NLSs can bind to importin-α as monopartite NLSs, which is in agreement with some previous studies. However, MLH1-NLS has the highest affinity measured by a natural NLS peptide, suggesting a major role of MLH1 protein in nuclear import compared to PMS2. Finally, the role of MLH1 and PMS2 in the nuclear transport of the MutLα heterodimer is discussed. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

A multifactorial likelihood model for MMR gene variant classification incorporating probabilities based on sequence bioinformatics and tumor characteristics: a report from the Colon Cancer Family Registry.

Science.gov (United States)

Thompson, Bryony A; Goldgar, David E; Paterson, Carol; Clendenning, Mark; Walters, Rhiannon; Arnold, Sven; Parsons, Michael T; Michael D, Walsh; Gallinger, Steven; Haile, Robert W; Hopper, John L; Jenkins, Mark A; Lemarchand, Loic; Lindor, Noralane M; Newcomb, Polly A; Thibodeau, Stephen N; Young, Joanne P; Buchanan, Daniel D; Tavtigian, Sean V; Spurdle, Amanda B

2013-01-01

Mismatch repair (MMR) gene sequence variants of uncertain clinical significance are often identified in suspected Lynch syndrome families, and this constitutes a challenge for both researchers and clinicians. Multifactorial likelihood model approaches provide a quantitative measure of MMR variant pathogenicity, but first require input of likelihood ratios (LRs) for different MMR variation-associated characteristics from appropriate, well-characterized reference datasets. Microsatellite instability (MSI) and somatic BRAF tumor data for unselected colorectal cancer probands of known pathogenic variant status were used to derive LRs for tumor characteristics using the Colon Cancer Family Registry (CFR) resource. These tumor LRs were combined with variant segregation within families, and estimates of prior probability of pathogenicity based on sequence conservation and position, to analyze 44 unclassified variants identified initially in Australasian Colon CFR families. In addition, in vitro splicing analyses were conducted on the subset of variants based on bioinformatic splicing predictions. The LR in favor of pathogenicity was estimated to be ~12-fold for a colorectal tumor with a BRAF mutation-negative MSI-H phenotype. For 31 of the 44 variants, the posterior probabilities of pathogenicity were such that altered clinical management would be indicated. Our findings provide a working multifactorial likelihood model for classification that carefully considers mode of ascertainment for gene testing. © 2012 Wiley Periodicals, Inc.

Splicing analysis for exonic and intronic mismatch repair gene variants associated with Lynch syndrome confirms high concordance between minigene assays and patient RNA analyses

Science.gov (United States)

van der Klift, Heleen M; Jansen, Anne M L; van der Steenstraten, Niki; Bik, Elsa C; Tops, Carli M J; Devilee, Peter; Wijnen, Juul T

2015-01-01

A subset of DNA variants causes genetic disease through aberrant splicing. Experimental splicing assays, either RT-PCR analyses of patient RNA or functional splicing reporter minigene assays, are required to evaluate the molecular nature of the splice defect. Here, we present minigene assays performed for 17 variants in the consensus splice site regions, 14 exonic variants outside these regions, and two deep intronic variants, all in the DNA mismatch-repair (MMR) genes MLH1, MSH2, MSH6, and PMS2, associated with Lynch syndrome. We also included two deep intronic variants in APC and PKD2. For one variant (MLH1 c.122A>G), our minigene assay and patient RNA analysis could not confirm the previously reported aberrant splicing. The aim of our study was to further investigate the concordance between minigene splicing assays and patient RNA analyses. For 30 variants results from patient RNA analyses were available, either performed by our laboratory or presented in literature. Some variants were deliberately included in this study because they resulted in multiple aberrant transcripts in patient RNA analysis, or caused a splice effect other than the prevalent exon skip. While both methods were completely concordant in the assessment of splice effects, four variants exhibited major differences in aberrant splice patterns. Based on the present and earlier studies, together showing an almost 100% concordance of minigene assays with patient RNA analyses, we discuss the weight given to minigene splicing assays in the current criteria proposed by InSiGHT for clinical classification of MMR variants. PMID:26247049

SERIES: Genomic instability in cancer Balancing repair and tolerance of DNA damage caused by alkylating agents

Science.gov (United States)

Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D

2013-01-01

Alkylating agents comprise a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER), and mismatch repair (MMR) respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for an organism's favorable response to alkylating agents. Furthermore, an individual's response to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity. PMID:22237395

Mismatch repair proteins, meiosis, and mice: understanding the complexities of mammalian meiosis.

Science.gov (United States)

Svetlanov, Anton; Cohen, Paula E

2004-05-15

Mammalian meiosis differs from that seen in lower eukaryotes in several respects, not least of which is the added complexity of dealing with chromosomal interactions across a much larger genome (12 MB over 16 chromosome pairs in Saccharomyces cerevisiae compared to 2500 MB over 19 autosome pairs in Mus musculus). Thus, the recombination machinery, while being highly conserved through eukaryotes, has evolved to accommodate such issues to preserve genome integrity and to ensure propagation of the species. One group of highly conserved meiotic regulators is the DNA mismatch repair protein family that, as their name implies, were first identified as proteins that act to repair DNA mismatches that arise primarily during DNA replication. Their function in ensuring chromosomal integrity has also translated into a critical role for this family in meiotic recombination in most sexually reproducing organisms. In mice, targeted deletion of certain family members results in severe consequences for meiotic progression and infertility. This review will focus on the studies involving these mutant mouse models, with occasional comparison to the function of these proteins in other organisms.

Estrogen enhances mismatch repair by induction of MLH1 expression via estrogen receptor-β.

Science.gov (United States)

Lu, Jun-Yu; Jin, Peng; Gao, Wei; Wang, De-Zhi; Sheng, Jian-Qiu

2017-06-13

Epidemiological data demonstrated that hormone replace treatment has protective effect against colorectal cancer (CRC). Our previous studies showed that this effect may be associated with DNA mismatch repair. This study aims to investigate the mechanism of estrogen induction of MLH1, and whether colorectal tumor proliferation can be inhibited through induction of MLH1 by estrogen signal pathway. Human CRC cell lines were used to examine the regulation of MLH1 expression by over-expression and depletion of estrogen receptor-α (ERα) and estrogen receptor-β (ERβ), under the treatment with 17β-estradiol or β-Estradiol 6-(O-carboxy-methyl)oxime:BSA, followed by a real-time Q-PCR and Western blotting analysis. Luciferase reporter and chromatin immunoprecipitation assays were used to identify the estrogen response elements in the proximal promoter of MLH1 gene. Then, the influence of estrogen-induced MLH1 on CRC tumor growth were determined in vitro and in vivo. We found that mismatch repair ability and microsatellite stability of cells were enhanced by estrogen via induction of MLH1 expression, which was mediated by ERβ, through a transcriptional activation process. Furthermore, we identified that ERβ exerted an inhibitory effect on CRC tumor proliferation in vitro and in vivo, combined with 5-FU, through up-regulation of MLH1 expression. Finally, we concluded that estrogen enhances mismatch repair ability and tumor inhibition effect in vitro and in vivo, via induction of MLH1 expression mediated by ERβ.

Challenges in the identification of MSH6-associated colorectal cancer: rectal location, less typical histology, and a subset with retained mismatch repair function

DEFF Research Database (Denmark)

Klarskov, Louise; Holck, Susanne; Bernstein, Inge

2011-01-01

with MLH1/MSH2-mutant tumors and sporadic mismatch repair-deficient cancers. In the MSH6 subset, we confirmed a higher age (median, 56 y) at diagnosis and found a significantly larger proportion (25%) of rectal cancers. Presence of dirty necrosis was the sole histologic component that significantly...... differed between MSH6 and MLH1/MSH2 tumors. Compared with the sporadic mismatch repair-defective cohort, MSH6 cases had a lower prevalence of tumor-infiltrating lymphocytes and Crohn-like reactions. Mismatch repair defects were identified in 92% of MSH6 tumors, with high concordance between microsatellite...

Challenges in the Identification of MSH6-Associated Colorectal Cancer: Rectal Location, Less Typical Histology, and a Subset With Retained Mismatch Repair Function

DEFF Research Database (Denmark)

Klarskov, Louise Laurberg; Holck, Susanne; Bernstein, Inge Thomsen

2011-01-01

with MLH1/MSH2-mutant tumors and sporadic mismatch repair-deficient cancers. In the MSH6 subset, we confirmed a higher age (median, 56 y) at diagnosis and found a significantly larger proportion (25%) of rectal cancers. Presence of dirty necrosis was the sole histologic component that significantly...... differed between MSH6 and MLH1/MSH2 tumors. Compared with the sporadic mismatch repair-defective cohort, MSH6 cases had a lower prevalence of tumor-infiltrating lymphocytes and Crohn-like reactions. Mismatch repair defects were identified in 92% of MSH6 tumors, with high concordance between microsatellite...

Germ line mutations of mismatch repair genes in hereditary nonpolyposis colorectal cancer patients with small bowel cancer: International Society for Gastrointestinal Hereditary Tumours Collaborative Study

DEFF Research Database (Denmark)

Park, Jae-Gahb; Kim, Duck-Woo; Hong, Chang Won

2006-01-01

PURPOSE: The aim of study was to determine the clinical characteristics and mutational profiles of the mismatch repair genes in hereditary nonpolyposis colorectal cancer (HNPCC) patients with small bowel cancer (SBC). EXPERIMENTAL DESIGN: A questionnaire was mailed to 55 members of the Internatio......PURPOSE: The aim of study was to determine the clinical characteristics and mutational profiles of the mismatch repair genes in hereditary nonpolyposis colorectal cancer (HNPCC) patients with small bowel cancer (SBC). EXPERIMENTAL DESIGN: A questionnaire was mailed to 55 members...... of the International Society for Gastrointestinal Hereditary Tumours, requesting information regarding patients with HNPCC-associated SBC and germ line mismatch repair gene mutations. RESULTS: The study population consisted of 85 HNPCC patients with identified mismatch repair gene mutations and SBCs. SBC was the first...... HNPCC-associated malignancy in 14 of 41 (34.1%) patients for whom a personal history of HNPCC-associated cancers was available. The study population harbored 69 different germ line mismatch repair gene mutations, including 31 mutations in MLH1, 34 in MSH2, 3 in MSH6, and 1 in PMS2. We compared...

Variations in mismatch repair genes and colorectal cancer risk and clinical outcome

Czech Academy of Sciences Publication Activity Database

Vymetálková, Veronika; Pardini, B.; Rosa, F.; Di Gaetano, C.; Novotný, J.; Levý, M.; Buchler, T.; Slyšková, Jana; Vodičková, Ludmila; Naccarati, Alessio; Vodička, Pavel

2014-01-01

Roč. 29, č. 4 (2014), s. 259-265 ISSN 0267-8357 R&D Projects: GA ČR GPP304/11/P715; GA ČR GAP304/10/1286; GA MZd NT12025 Institutional support: RVO:68378041 Keywords : colorectal cancer , , * mismatch repair genes * miRNA Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.793, year: 2014

Approaches to diagnose DNA mismatch repair gene defects in cancer

DEFF Research Database (Denmark)

Peña-Diaz, Javier; Rasmussen, Lene Juel

2016-01-01

development was first observed in colorectal cancer patients that carried inactivating germline mutations in MMR genes and the disease was named as hereditary non-polyposis colorectal cancer (HNPCC). Currently, a growing list of cancers is found to be MMR defective and HNPCC has been renamed Lynch syndrome...

Development of in vitro and in vivo functional assays to enable diagnosis of Variants of Uncertain Significance in the common cancer predisposition Lynch syndrome

NARCIS (Netherlands)

Drost, Mark

2014-01-01

Lynch syndrome (LS) is caused by germline mutations in DNA mismatch repair (MMR) genes and is the most prevalent hereditary colorectal cancer syndrome. A significant proportion of variants identified in MMR and other common cancer susceptibility genes are missense or noncoding changes whose

The changing landscape of Lynch syndrome due to PMS2 mutations.

Science.gov (United States)

Blount, J; Prakash, A

2018-07-01

DNA repair pathways are essential for cellular survival as our DNA is constantly under assault from both exogenous and endogenous DNA damaging agents. Five major mammalian DNA repair pathways exist within a cell to maintain genomic integrity. Of these, the DNA mismatch repair (MMR) pathway is highly conserved among species and is well documented in bacteria. In humans, the importance of MMR is underscored by the discovery that a single mutation in any 1 of 4 genes within the MMR pathway (MLH1, MSH2, MSH6 and PMS2) results in Lynch syndrome (LS). LS is a autosomal dominant condition that predisposes individuals to a higher incidence of many malignancies including colorectal, endometrial, ovarian, and gastric cancers. In this review, we discuss the role of PMS2 in the MMR pathway, the evolving testing criteria used to identify variants in the PMS2 gene, the LS phenotype as well as the autosomal recessive condition called constitutional mismatch repair deficiency syndrome, and current methods used to elucidate the clinical impact of PMS2 mutations. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Constitutional mismatch repair deficiency and Lynch syndrome among consecutive Arab Bedouins with colorectal cancer in Israel.

Science.gov (United States)

Abu Freha, Naim; Leibovici Weissman, Yaara; Fich, Alexander; Barnes Kedar, Inbal; Halpern, Marisa; Sztarkier, Ignacio; Behar, Doron M; Arbib Sneh, Orly; Vilkin, Alex; Baris, Hagit N; Gingold, Rachel; Lejbkowicz, Flavio; Niv, Yaron; Goldberg, Yael; Levi, Zohar

2018-01-01

We assessed the molecular characteristics and the frequency of mutations in mismatch-repair genes among Bedouin patients with colorectal cancer (CRC) in Israel. Bedouin patients with a diagnosis of CRC at a major hospital in the southern part of Israel were deemed eligible for this study. The primary screening method was immunohistochemical staining for mismatch-repair proteins (MLH1, MSH2, MSH6, and PMS2). For subjects with abnormal immunohistochemical staining, we performed microsatellite instability (MSI) analyses, and for tumors with a loss of MLH1 expression we also performed BRAF testing. In MSI high cases we searched further for germline mutations. Of the 24 patients enrolled, four subjects (16.7%) had MSI high tumors: one subject was found to harbor a biallelic PMS2 mutation, one subject had Lynch syndrome (LS) with MSH6 mutation and two subjects had a loss of MLH1/PMS2 proteins/BRAF wild type /normal MLH1 sequence. Ten patients (41.7%) were younger than 50 at the time of diagnosis and none had first degree relatives with CRC. In conclusion, in this cohort of 24 consecutive Arab Bedouins with CRC, one patient was found to harbor a constitutional mismatch repair deficiency, one patient had LS with MSH6 mutation, and two patients had unresolved loss of MLH1/PMS2 proteins/BRAF wild type phenotype.

Role of DNA mismatch repair and p53 in signaling induction of apoptosis by alkylating agents.

Science.gov (United States)

Hickman, M J; Samson, L D

1999-09-14

All cells are unavoidably exposed to chemicals that can alkylate DNA to form genotoxic damage. Among the various DNA lesions formed, O(6)-alkylguanine lesions can be highly cytotoxic, and we recently demonstrated that O(6)-methylguanine (O(6)MeG) and O(6)-chloroethylguanine (O(6)CEG) specifically initiate apoptosis in hamster cells. Here we show, in both hamster and human cells, that the MutSalpha branch of the DNA mismatch repair pathway (but not the MutSbeta branch) is absolutely required for signaling the initiation of apoptosis in response to O(6)MeGs and is partially required for signaling apoptosis in response to O(6)CEGs. Further, O(6)MeG lesions signal the stabilization of the p53 tumor suppressor, and such signaling is also MutSalpha-dependent. Despite this, MutSalpha-dependent apoptosis can be executed in a p53-independent manner. DNA mismatch repair status did not influence the response of cells to other inducers of p53 and apoptosis. Thus, it appears that mismatch repair status, rather than p53 status, is a strong indicator of the susceptibility of cells to alkylation-induced apoptosis. This experimental system will allow dissection of the signal transduction events that couple a specific type of DNA base lesion with the final outcome of apoptotic cell death.

Expression of DNA mismatch repair proteins MLH1, MSH2, and MSH6 in recurrent glioblastoma.

Science.gov (United States)

Stark, Andreas M; Doukas, Alexander; Hugo, Heinz-Herrmann; Hedderich, Jürgen; Hattermann, Kirsten; Maximilian Mehdorn, H; Held-Feindt, Janka

2015-02-01

Methylated O6-methylguanin-DNA-methytransferase (MGMT) promoter methylation is associated with survival in patients with glioblastoma. Current evidence suggests that further mismatch repair genes play a pivotal role in the tumor response to treatment. Candidate genes are MLH1, MSH2, and MSH6. Formerly, we found evidence of prognostic impact of MLH1 and MSH6 immunohistochemical expression in a small series of patients with initial glioblastoma. Two hundred and eleven patients were included who underwent macroscopically total removal of primary glioblastoma and at least one re-craniotomy for recurrence. Immunohistochemical staining was performed on paraffin-embedded specimens of initial tumors with specific antibodies against MLH1, MSH2, and MSH6. RESULTS were compared to the Ki67 proliferation index and patient survival. Additionally, fresh frozen samples from 16 paired initial and recurrent specimens were examined using real-time reverse transcription polymerase chain reaction (RT-PCR) with specific primers against MLH1, MSH2, and MSH6. RESULTS were compared to MGMT status and survival. (1) Immunohistochemical expression of MSH6 was significantly associated with the Ki67 proliferation index (PMLH1, MLH2, and MSH6 over treatment combined with lacking MGMT methylation. In another two patients, decreased MLH1, MSH2, and MSH6 expression was observed in combination with MGMT promoter methylation. Our data indicate that there may be glioblastoma patient subgroups characterized by MMR-expression changes beyond MGMT promoter methylation. The immunohistochemical expression of MLH1, MSH2, and MSH6 in initial glioblastoma is not associated with patient survival.

Repair of DNA damage induced by anthanthrene, a polycyclic aromatic hydrocarbon (PAH) without bay or fjord regions

DEFF Research Database (Denmark)

Madsen, Claus Desler; Johannessen, Christian; Rasmussen, Lene Juel

2009-01-01

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants, formed during incomplete burning of coal, oil and gas. Several PAHs have carcinogenic and mutagenic potencies, but these compounds must be activated in order to exert their mutagenic effects. One of the principal pathways...... proposed for metabolic activation of PAHs involves the cytochrome P450 enzymes. The DNA damaging potential of cytochrome P450-activated PAHs is generally associated with their bay and fjord regions, and the DNA repair response of PAHs containing such regions has been thoroughly studied. However, little...... in response to DNA damage induced by cytochrome P450-activated anthanthrene. In cell extracts, functional nucleotide excision repair (NER) and mismatch repair (MMR) activities were necessary to trigger a response to anthanthrene metabolite-induced DNA damage. In cell cultures, NER was responsible...

Constitutional mismatch repair deficiency presenting in childhood as three simultaneous malignancies.

Science.gov (United States)

Walter, Andrew W; Ennis, Sara; Best, Hunter; Vaughn, Cecily P; Swensen, Jeffrey J; Openshaw, Amanda; Gripp, Karen W

2013-11-01

A 13-year-old child presented with three simultaneous malignancies: glioblastoma multiforme, Burkitt lymphoma, and colonic adenocarcinoma. She was treated for her diseases without success and died 8 months after presentation. Genetic analysis revealed a homozygous mutation in the PMS2 gene, consistent with constitutional mismatch repair deficiency. Her siblings and parents were screened: three of four siblings and both parents were heterozygous for this mutation; the fourth sibling did not have the mutation. Copyright © 2013 Wiley Periodicals, Inc.

Biological effects of simple changes in functionality on rhodium metalloinsertors

Science.gov (United States)

Weidmann, Alyson G.; Komor, Alexis C.; Barton, Jacqueline K.

2013-01-01

DNA mismatch repair (MMR) is crucial to ensuring the fidelity of the genome. The inability to correct single base mismatches leads to elevated mutation rates and carcinogenesis. Using metalloinsertors–bulky metal complexes that bind with high specificity to mismatched sites in the DNA duplex–our laboratory has adopted a new chemotherapeutic strategy through the selective targeting of MMR-deficient cells, that is, those that have a propensity for cancerous transformation. Rhodium metalloinsertors display inhibitory effects selectively in cells that are deficient in the MMR machinery, consistent with this strategy. However, a highly sensitive structure–function relationship is emerging with the development of new complexes that highlights the importance of subcellular localization. We have found that small structural modifications, for example a hydroxyl versus a methyl functional group, can yield profound differences in biological function. Despite similar binding affinities and selectivities for DNA mismatches, only one metalloinsertor shows selective inhibition of cellular proliferation in MMR-deficient versus -proficient cells. Studies of whole-cell, nuclear and mitochondrial uptake reveal that this selectivity depends upon targeting DNA mismatches in the cell nucleus. PMID:23776288

Purification, crystallization and preliminary X-ray diffraction analysis of the human mismatch repair protein MutSβ

International Nuclear Information System (INIS)

Tseng, Quincy; Orans, Jillian; Hast, Michael A.; Iyer, Ravi R.; Changela, Anita; Modrich, Paul L.; Beese, Lorena S.

2011-01-01

Human MutSβ is a 232 kDa heterodimer (MSH2–MSH3) involved in the lesion-recognition step of mismatch repair. Here, the overexpression, purification, biochemical characterization and cocrystallization of MutSβ with a duplex DNA substrate are reported. MutSβ is a eukaryotic mismatch repair protein that preferentially targets extrahelical unpaired nucleotides and shares partial functional redundancy with MutSα (MSH2–MSH6). Although mismatch recognition by MutSα has been shown to involve a conserved Phe-X-Glu motif, little is known about the lesion-binding mechanism of MutSβ. Combined MSH3/MSH6 deficiency triggers a strong predisposition to cancer in mice and defects in msh2 and msh6 account for roughly half of hereditary nonpolyposis colorectal cancer mutations. These three MutS homologs are also believed to play a role in trinucleotide repeat instability, which is a hallmark of many neurodegenerative disorders. The baculovirus overexpression and purification of recombinant human MutSβ and three truncation mutants are presented here. Binding assays with heteroduplex DNA were carried out for biochemical characterization. Crystallization and preliminary X-ray diffraction analysis of the protein bound to a heteroduplex DNA substrate are also reported

Detection of mismatch repair gene germline mutation carrier among Chinese population with colorectal cancer

International Nuclear Information System (INIS)

Jin, Hei-Ying; Zhao, Ronghua; Liu, Xiufang; Li, Vicky Ka Ming; Ding, Yijiang; Yang, Bolin; Geng, Jianxiang; Lai, Rensheng; Ding, Shuqing; Ni, Min

2008-01-01

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant syndrome. The National Cancer Institute (NCI) has recommended the Revised Bethesda guidelines for screening HNPCC. There has been a great deal of research on the value of these tests in other countries. However, literature about the Chinese population is scarce. Our objective is to detect and study microsatellite instability (MSI) and mismatch repair (MMR) gene germline mutation carriers among a Chinese population with colorectal cancer. In 146 prospectively recruited consecutive patients with clinically proven colorectal cancer, MSI carriers were identified by analysis of tumor tissue using multiplex fluorescence polymerase chain reaction (PCR) using the NCI recommended panel and classified into microsatellite instability-low (MSI-L), microsatellite instability-high (MSI-H) and microsatellite stable (MSS) groups. Immunohistochemical staining for MSH2, MSH6 and MLH1 on tissue microarrays (TMAs) was performed, and methylation of the MLH1 promoter was analyzed by quantitative methylation specific PCR (MSP). Germline mutation analysis of blood samples was performed for MSH2, MSH6 and MLH1 genes. Thirty-four out of the 146 colorectal cancers (CRCs, 23.2%) were MSI, including 19 MSI-H CRCs and 15 MSI-L CRCS. Negative staining for MSH2 was found in 8 CRCs, negative staining for MSH6 was found in 6 CRCs. One MSI-H CRC was negative for both MSH6 and MSH2. Seventeen CRCs stained negatively for MLH1. MLH1 promoter methylation was determined in 34 MSI CRCs. Hypermethylation of the MLH1 promoter occurred in 14 (73.7%) out of 19 MSI-H CRCs and 5 (33.3%) out of 15 MSI-L CRCs. Among the 34 MSI carriers and one MSS CRC with MLH1 negative staining, 8 had a MMR gene germline mutation, which accounted for 23.5% of all MSI colorectal cancers and 5.5% of all the colorectal cancers. Five patients harbored MSH2 germline mutations, and three patients harbored MSH6 germline mutations. None of the patients had an MLH

Do polymorphisms and haplotypes of mismatch repair genes modulate risk of sporadic colorectal cancer?

Czech Academy of Sciences Publication Activity Database

Tulupová, Elena; Kumar, R.; Hánová, Monika; Slyšková, Jana; Pardini, Barbara; Poláková, Veronika; Naccarati, Alessio; Vodičková, Ludmila; Novotný, J.; Halamková, J.; Hemminki, K.; Vodička, Pavel

2008-01-01

Roč. 648, 1-2 (2008), s. 40-45 ISSN 0027-5107 R&D Projects: GA ČR GA310/07/1430 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z50390703 Keywords : DNA mismatch repair * Genetic polymorphism * Haplotype analysis Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.198, year: 2008

Immunohistochemistry for PMS2 and MSH6 alone can replace a four antibody panel for mismatch repair deficiency screening in colorectal adenocarcinoma.

Science.gov (United States)

Hall, Geoffrey; Clarkson, Adele; Shi, Amanda; Langford, Eileen; Leung, Helen; Eckstein, Robert P; Gill, Anthony J

2010-01-01

Currently, testing for mismatch repair deficiency in colorectal cancers is initiated by performing immunohistochemistry with four antibodies (MLH1, PMS2, MSH2 and MSH6). If any one of these stains is negative the tumour is considered microsatellite unstable and, if clinical circumstances warrant it, the patient is offered genetic testing for Lynch's syndrome. Due to the binding properties of the mismatch repair heterodimer complexes, gene mutation and loss of MLH1 and MSH2 invariably result in the degradation of PMS2 and MSH6, respectively, but the converse is not true. We propose that staining for PMS2 and MSH6 alone will be sufficient to detect all cases of mismatch repair deficiency and should replace routine screening with all four antibodies. The electronic database of the department of Anatomical Pathology, Royal North Shore Hospital, Sydney, Australia, was searched for all colorectal carcinomas on which a four panel immunohistochemical microsatellite instability screen was performed. An audit of the slides for concordant loss of MLH1-PMS2 and MSH2-MSH6 was then undertaken. Unusual or discordant cases were reviewed and, in some cases, re-stained to confirm the staining pattern. Of 344 cases of colorectal cancer which underwent four antibody immunohistochemistry, 104 displayed loss of at least one mismatch repair protein. Of these, 100 showed concordant mismatch repair loss (i.e., loss of MLH1 and PMS2 or loss of MSH2 and MSH6). The four discordant cases comprised two single negative cases (1 MSH6 negative/MSH2 positive case, 1 PMS2 negative/MLH1 positive) and two triple negative (both MLH1/PMS2/MSH6 negative). The microsatellite instability (MSI) group showed a relatively high median age (69.3 years) due to the departmental policy of testing all cases with possible MSI morphology regardless of age. The sensitivity and specificity of a two panel test comprised of PMS2 and MSH6, compared to a four panel test, is 100%. No false negatives or positives were

PMS2 gene mutation results in DNA mismatch repair system failure in a case of adult granulosa cell tumor.

Science.gov (United States)

Wang, Wen-Chung; Lee, Ya-Ting; Lai, Yen-Chein

2017-03-27

Granulosa cell tumors are rare ovarian malignancies. Their characteristics include unpredictable indolent growth with malignant potential and late recurrence. Approximately 95% are of adult type. Recent molecular studies have characterized the FOXL2 402C > G mutation in adult granulosa cell tumor. Our previous case report showed that unique FOXL2 402C > G mutation and defective DNA mismatch repair system are associated with the development of adult granulosa cell tumor. In this study, the DNA sequences of four genes, MSH2, MLH1, MSH6, and PMS2, in the DNA mismatch repair system were determined via direct sequencing to elucidate the exact mechanism for the development of this granulosa cell tumor. The results showed that two missense germline mutations, T485K and N775L, inactivate the PMS2 gene. The results of this case study indicated that although FOXL2 402C > G mutation determines the development of granulosa cell tumor, PMS2 mutation may be the initial driver of carcinogenesis. Immunohistochemistry-based tumor testing for mismatch repair gene expression may be necessary for granulosa cell tumors to determine their malignant potential or if they are part of Lynch syndrome.

Molecular characteristics of mismatch repair genes in sporadic colorectal tumors in Czech patients

Czech Academy of Sciences Publication Activity Database

Vymetálková, Veronika; Slyšková, Jana; Korenková, Vlasta; Bielik, Ludovít; Langerová, Lucie; Procházka, Pavel; Rejhová, Alexandra; Schwarzová, L.; Pardini, B.; Naccarati, Alessio; Vodička, Pavel

2014-01-01

Roč. 15, č. 1 (2014), s. 17 ISSN 1471-2350 R&D Projects: GA AV ČR IAA500200917; GA ČR(CZ) GPP304/11/P715 Grant - others:GA MŠk(CZ) Prvouk-P27/LF1/1 Institutional support: RVO:68378041 ; RVO:86652036 Keywords : colorectal cancer * mismatch repair genes * expression levels Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.083, year: 2014

Biallelic PMS2 Mutation and Heterozygous DICER1 Mutation Presenting as Constitutional Mismatch Repair Deficiency With Corpus Callosum Agenesis: Case Report and Review of Literature.

Science.gov (United States)

Cheyuo, Cletus; Radwan, Walid; Ahn, Janice; Gyure, Kymberly; Qaiser, Rabia; Tomboc, Patrick

2017-10-01

Constitutional mismatch repair deficiency syndrome is a cancer predisposition syndrome caused by autosomal recessive biallelic (homozygous) germline mutations in the mismatch repair genes (MLH1, MSH2, MSH6, and PMS2). The clinical spectrum includes neoplastic and non-neoplastic manifestations. We present the case of a 7-year-old boy who presented with T-lymphoblastic lymphoma and glioblastoma, together with non-neoplastic manifestations including corpus callosum agenesis, arachnoid cyst, developmental venous anomaly, and hydrocephalus. Gene mutation analysis revealed pathogenic biallelic mutations of PMS2 and heterozygous DICER1 variant predicted to be pathogenic. This report is the first to allude to a possible interaction of the mismatch repair system with DICER1 to cause corpus callosum agenesis.

Apoptotic function of human PMS2 compromised by the nonsynonymous single-nucleotide polymorphic variant R20Q

OpenAIRE

Marinovic-Terzic, Ivana; Yoshioka-Yamashita, Atsuko; Shimodaira, Hideki; Avdievich, Elena; Hunton, Irina C.; Kolodner, Richard D.; Edelmann, Winfried; Wang, Jean Y. J.

2008-01-01

Mismatch repair (MMR) corrects replication errors during DNA synthesis. The mammalian MMR proteins also activate cell cycle checkpoints and apoptosis in response to persistent DNA damage. MMR-deficient cells are resistant to cisplatin, a DNA cross-linking agent used in chemotherapy, because of impaired activation of apoptotic pathways. It is shown that postmeiotic segregation 2 (PMS2), an MMR protein, is required for cisplatin-induced activation of p73, a member of the p53 family of transcrip...

The role of mismatch repair in small-cell lung cancer cells

DEFF Research Database (Denmark)

Hansen, L T; Thykjaer, T; Ørntoft, T F

2003-01-01

pattern of MMR gene expression. A significant correlation between the mRNA and protein levels was found. We demonstrate that low hMLH1 gene expression was not linked to promoter CpG methylation. One cell line (86MI) was found to be deficient in MMR and exhibited resistance to the alkylating agent MNNG...

TumorNext-Lynch-MMR: a comprehensive next generation sequencing assay for the detection of germline and somatic mutations in genes associated with mismatch repair deficiency and Lynch syndrome.

Science.gov (United States)

Gray, Phillip N; Tsai, Pei; Chen, Daniel; Wu, Sitao; Hoo, Jayne; Mu, Wenbo; Li, Bing; Vuong, Huy; Lu, Hsiao-Mei; Batth, Navanjot; Willett, Sara; Uyeda, Lisa; Shah, Swati; Gau, Chia-Ling; Umali, Monalyn; Espenschied, Carin; Janicek, Mike; Brown, Sandra; Margileth, David; Dobrea, Lavinia; Wagman, Lawrence; Rana, Huma; Hall, Michael J; Ross, Theodora; Terdiman, Jonathan; Cullinane, Carey; Ries, Savita; Totten, Ellen; Elliott, Aaron M

2018-04-17

The current algorithm for Lynch syndrome diagnosis is highly complex with multiple steps which can result in an extended time to diagnosis while depleting precious tumor specimens. Here we describe the analytical validation of a custom probe-based NGS tumor panel, TumorNext-Lynch-MMR, which generates a comprehensive genetic profile of both germline and somatic mutations that can accelerate and streamline the time to diagnosis and preserve specimen. TumorNext-Lynch-MMR can detect single nucleotide variants, small insertions and deletions in 39 genes that are frequently mutated in Lynch syndrome and colorectal cancer. Moreover, the panel provides microsatellite instability status and detects loss of heterozygosity in the five Lynch genes; MSH2 , MSH6 , MLH1 , PMS2 and EPCAM . Clinical cases are described that highlight the assays ability to differentiate between somatic and germline mutations, precisely classify variants and resolve discordant cases.

Value-based healthcare in Lynch syndrome

NARCIS (Netherlands)

Hennink, Simone D; Hofland, N.; Gopie, J.P.; van der Kaa, C.; de Koning, K.; Nielsen, M.; Tops, C.; Morreau, H.; de Vos Tot Nederveen Cappel, W.H.; Langers, A.M.; Hardwick, J.C.; Gaarenstroom, K.N.; Tollenaar, R.A.; Veenendaal, R.A.; Tibben, A.; Wijnen, J.; van Heck, M.; van Asperen, C.; Roukema, J.A.; Hommes, D.W.; Hes, F.J.; Vasen, H.F.A.

2013-01-01

Lynch syndrome (LS), one of the most frequent forms of hereditary colorectal cancer (CRC), is caused by a defect in one of the mismatch repair (MMR) genes. Carriers of MMR defects have a strongly increased risk of developing CRC and endometrial cancer. Over the last few years, value-based healthcare

Stabilization of the genome of the mismatch repair deficient Mycobacterium tuberculosis by context-dependent codon choice.

Science.gov (United States)

Wanner, Roger M; Güthlein, Carolin; Springer, Burkhard; Böttger, Erik C; Ackermann, Martin

2008-05-28

The rate at which a stretch of DNA mutates is determined by the cellular systems for DNA replication and repair, and by the nucleotide sequence of the stretch itself. One sequence feature with a particularly strong influence on the mutation rate are nucleotide repeats. Some microbial pathogens use nucleotide repeats in their genome to stochastically vary phenotypic traits and thereby evade host defense. However, such unstable sequences also come at a cost, as mutations are often deleterious. Here, we analyzed how these opposing forces shaped genome stability in the human pathogen Mycobacterium tuberculosis. M. tuberculosis lacks a mismatch repair system, and this renders nucleotide repeats particularly unstable. We found that proteins of M. tuberculosis are encoded by using codons in a context-dependent manner that prevents the emergence of nucleotide repeats. This context-dependent codon choice leads to a strong decrease in the estimated frame-shift mutation rate and thus to an increase in genome stability. These results indicate that a context-specific codon choice can partially compensate for the lack of a mismatch repair system, and helps to maintain genome integrity in this pathogen.

Stabilization of the genome of the mismatch repair deficient Mycobacterium tuberculosis by context-dependent codon choice

Directory of Open Access Journals (Sweden)

Ackermann Martin

2008-05-01

Full Text Available Abstract Background The rate at which a stretch of DNA mutates is determined by the cellular systems for DNA replication and repair, and by the nucleotide sequence of the stretch itself. One sequence feature with a particularly strong influence on the mutation rate are nucleotide repeats. Some microbial pathogens use nucleotide repeats in their genome to stochastically vary phenotypic traits and thereby evade host defense. However, such unstable sequences also come at a cost, as mutations are often deleterious. Here, we analyzed how these opposing forces shaped genome stability in the human pathogen Mycobacterium tuberculosis. M. tuberculosis lacks a mismatch repair system, and this renders nucleotide repeats particularly unstable. Results We found that proteins of M. tuberculosis are encoded by using codons in a context-dependent manner that prevents the emergence of nucleotide repeats. This context-dependent codon choice leads to a strong decrease in the estimated frame-shift mutation rate and thus to an increase in genome stability. Conclusion These results indicate that a context-specific codon choice can partially compensate for the lack of a mismatch repair system, and helps to maintain genome integrity in this pathogen.

Predictive genetic testing in children: constitutional mismatch repair deficiency cancer predisposing syndrome.

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Bruwer, Zandrè; Algar, Ursula; Vorster, Alvera; Fieggen, Karen; Davidson, Alan; Goldberg, Paul; Wainwright, Helen; Ramesar, Rajkumar

2014-04-01

Biallelic germline mutations in mismatch repair genes predispose to constitutional mismatch repair deficiency syndrome (CMMR-D). The condition is characterized by a broad spectrum of early-onset tumors, including hematological, brain and bowel and is frequently associated with features of Neurofibromatosis type 1. Few definitive screening recommendations have been suggested and no published reports have described predictive testing. We report on the first case of predictive testing for CMMR-D following the identification of two non-consanguineous parents, with the same heterozygous mutation in MLH1: c.1528C > T. The genetic counseling offered to the family, for their two at-risk daughters, is discussed with a focus on the ethical considerations of testing children for known cancer-causing variants. The challenges that are encountered when reporting on heterozygosity in a child younger than 18 years (disclosure of carrier status and risk for Lynch syndrome), when discovered during testing for homozygosity, are addressed. In addition, the identification of CMMR-D in a three year old, and the recommended clinical surveillance that was proposed for this individual is discussed. Despite predictive testing and presymptomatic screening, the sudden death of the child with CMMR-D syndrome occurred 6 months after her last surveillance MRI. This report further highlights the difficulty of developing guidelines, as a result of the rarity of cases and diversity of presentation.

Cell-Selective Biological Activity of Rhodium Metalloinsertors Correlates with Subcellular Localization

Science.gov (United States)

Komor, Alexis C.; Schneider, Curtis J.; Weidmann, Alyson G.; Barton, Jacqueline K.

2013-01-01

Deficiencies in the mismatch repair (MMR) pathway are associated with several types of cancers, as well as resistance to commonly used chemotherapeutics. Rhodium metalloinsertors have been found to bind DNA mismatches with high affinity and specificity in vitro, and also exhibit cell-selective cytotoxicity, targeting MMR-deficient cells over MMR-proficient cells. Ten distinct metalloinsertors with varying lipophilicities have been synthesized and their mismatch binding affinities and biological activities determined. Although DNA photocleavage experiments demonstrate that their binding affinities are quite similar, their cell-selective antiproliferative and cytotoxic activities vary significantly. Inductively coupled plasma mass spectrometry (ICP-MS) experiments have uncovered a relationship between the subcellular distribution of these metalloinsertors and their biological activities. Specifically, we find that all of our metalloinsertors localize in the nucleus at sufficient concentrations for binding to DNA mismatches. However, the metalloinsertors with high rhodium localization in the mitochondria show toxicity that is not selective for MMR-deficient cells, whereas metalloinsertors with less mitochondrial rhodium show activity that is highly selective for MMR-deficient versus proficient cells. This work supports the notion that specific targeting of the metalloinsertors to nuclear DNA gives rise to their cell-selective cytotoxic and antiproliferative activities. The selectivity in cellular targeting depends upon binding to mismatches in genomic DNA. PMID:23137296

Genome-Wide Analysis of Heteroduplex DNA in Mismatch Repair–Deficient Yeast Cells Reveals Novel Properties of Meiotic Recombination Pathways

Science.gov (United States)

Martini, Emmanuelle; Borde, Valérie; Legendre, Matthieu; Audic, Stéphane; Regnault, Béatrice; Soubigou, Guillaume; Dujon, Bernard; Llorente, Bertrand

2011-01-01

Meiotic DNA double-strand breaks (DSBs) initiate crossover (CO) recombination, which is necessary for accurate chromosome segregation, but DSBs may also repair as non-crossovers (NCOs). Multiple recombination pathways with specific intermediates are expected to lead to COs and NCOs. We revisited the mechanisms of meiotic DSB repair and the regulation of CO formation, by conducting a genome-wide analysis of strand-transfer intermediates associated with recombination events. We performed this analysis in a SK1 × S288C Saccharomyces cerevisiae hybrid lacking the mismatch repair (MMR) protein Msh2, to allow efficient detection of heteroduplex DNAs (hDNAs). First, we observed that the anti-recombinogenic activity of MMR is responsible for a 20% drop in CO number, suggesting that in MMR–proficient cells some DSBs are repaired using the sister chromatid as a template when polymorphisms are present. Second, we observed that a large fraction of NCOs were associated with trans–hDNA tracts constrained to a single chromatid. This unexpected finding is compatible with dissolution of double Holliday junctions (dHJs) during repair, and it suggests the existence of a novel control point for CO formation at the level of the dHJ intermediate, in addition to the previously described control point before the dHJ formation step. Finally, we observed that COs are associated with complex hDNA patterns, confirming that the canonical double-strand break repair model is not sufficient to explain the formation of most COs. We propose that multiple factors contribute to the complexity of recombination intermediates. These factors include repair of nicks and double-stranded gaps, template switches between non-sister and sister chromatids, and HJ branch migration. Finally, the good correlation between the strand transfer properties observed in the absence of and in the presence of Msh2 suggests that the intermediates detected in the absence of Msh2 reflect normal intermediates. PMID

Nuclear translocation of mismatch repair proteins MSH2 and MSH6 as a response of cells to alkylating agents.

Science.gov (United States)

Christmann, M; Kaina, B

2000-11-17

Mammalian mismatch repair has been implicated in mismatch correction, the prevention of mutagenesis and cancer, and the induction of genotoxicity and apoptosis. Here, we show that treatment of cells specifically with agents inducing O(6)-methylguanine in DNA, such as N-methyl-N'-nitro-N-nitrosoguanidine and N-methyl-N-nitrosourea, elevates the level of MSH2 and MSH6 and increases GT mismatch binding activity in the nucleus. This inducible response occurs immediately after alkylation, is long-lasting and dose-dependent, and results from translocation of the preformed MutSalpha complex (composed of MSH2 and MSH6) from the cytoplasm into the nucleus. It is not caused by an increase in MSH2 gene activity. Cells expressing the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT), thus having the ability to repair O(6)-methylguanine, showed no translocation of MutSalpha, whereas inhibition of MGMT by O(6)-benzylguanine provoked the translocation. The results demonstrate that O(6)-methylguanine lesions are involved in triggering nuclear accumulation of MSH2 and MSH6. The finding that treatment of cells with O(6)-methylguanine-generating mutagens results in an increase of MutSalpha and GT binding activity in the nucleus indicates a novel type of genotoxic stress response.

Constitutioneel ‘mismatch repair’-deficiëntiesyndroom

NARCIS (Netherlands)

Jongmans, Marjolijn C.; Gidding, Corrie E.; Loeffen, Jan; Wesseling, Pieter; Mensenkamp, Arjen; Hoogerbrugge, Nicoline

2015-01-01

Constitutional mismatch repair deficiency (CMMRD) syndrome is characterised by a significantly increased risk for developing cancer in childhood. It arises when both parents have a mutation in the same mismatch repair gene and pass it on to their child. Case description An 8yearold girl was

Strategy in clinical practice for classification of unselected colorectal tumours based on mismatch repair deficiency

DEFF Research Database (Denmark)

Jensen, Lars Henrik; Lindebjerg, J; Byriel, L

2007-01-01

were collected. Expression of the MMR proteins MLH1, MSH2, and MSH6 by immunohistochemistry (IHC) was compared with MSI DNA analysis. Methylation analysis of MLH1 and mutation analysis for BRAF V600E were compared in samples with MSI and/or lack of MLH1 expression to determine if the tumour was likely...... to be sporadic. Results Thirty-nine (14.9%) of the tumours showed MMR deficiency by IHC or by microsatellite analysis. Sporadic inactivation by methylation of MLH1 promoter was found in 35 patients whereby the BRAF activating V600E mutation, indicating sporadic origin, was found in 32 tumours. On the basis...... of molecular characteristics we found 223 patients with intact MMR, 35 patients with sporadic MMR deficiency, and four patients who were likely to have hereditary MMR deficiency. Conclusion To obtain the maximal benefit for patients and clinicians, MMR testing should be supplemented with MLH1 methylation...

Genetic etiology of hereditary colorectal cancer: new mechanisms and advanced mutation detection techniques

NARCIS (Netherlands)

Gazzoli, I.

2006-01-01

The human DNA mismatch repair (MMR) system functions to repair mispaired bases in DNA that result from DNA replication errors and thereby prevents the accumulation of mutations due to such replication errors. Hereditary nonpolyposis colorectal cancer (HNPCC), the most common form of inherited colon

Acute lymphoblastic leukemia and lymphoma in the context of constitutional mismatch repair deficiency syndrome.

Science.gov (United States)

Ripperger, Tim; Schlegelberger, Brigitte

2016-03-01

Constitutional mismatch repair deficiency (CMMRD) syndrome is one of the rare diseases associated with a high risk of cancer. Causative mutations are found in DNA mismatch repair genes PMS2, MSH6, MSH2 or MLH1 that are well known in the context of Lynch syndrome. CMMRD follows an autosomal recessive inheritance trait and is characterized by childhood brain tumors and hematological malignancies as well as gastrointestinal cancer in the second and third decades of life. There is a high risk of multiple cancers, occurring synchronously and metachronously. In general, the prognosis is poor. About one third of CMMRD patients develop hematological malignancies as primary (sometimes the only) malignancy or as secondary neoplasm. T-cell non-Hodgkin lymphomas, mainly of mediastinal origin, are the most frequent hematological malignancies. Besides malignant diseases, non-neoplastic features are frequently observed, e.g. café-au-lait spots sometimes resembling neurofibromatosis type I, hypopigmented skin lesions, numerous adenomatous polyps, multiple pilomatricomas, or impaired immunoglobulin class switch recombination. Within the present review, we summarize previously published CMMRD patients with at least one hematological malignancy, provide an overview of steps necessary to substantiate the diagnosis of CMMRD, and refer to the recent most relevant literature. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Functional implications of the p.Cys680Arg mutation in the MLH1 mismatch repair protein

DEFF Research Database (Denmark)

Dominguez-Valentin, Mev; Drost, Mark; Therkildsen, Christina

2014-01-01

>C missense mutation in exon 18 of the human MLH1 gene and biochemically characterization of the p.Cys680Arg mutant MLH1 protein to implicate it in the pathogenicity of the Lynch syndrome (LS). We show that the mutation is deficient in DNA mismatch repair and, therefore, contributing to LS in the carriers....

Nickel induces transcriptional down-regulation of DNA repair pathways in tumorigenic and non-tumorigenic lung cells.

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Scanlon, Susan E; Scanlon, Christine D; Hegan, Denise C; Sulkowski, Parker L; Glazer, Peter M

2017-06-01

The heavy metal nickel is a known carcinogen, and occupational exposure to nickel compounds has been implicated in human lung and nasal cancers. Unlike many other environmental carcinogens, however, nickel does not directly induce DNA mutagenesis, and the mechanism of nickel-related carcinogenesis remains incompletely understood. Cellular nickel exposure leads to signaling pathway activation, transcriptional changes and epigenetic remodeling, processes also impacted by hypoxia, which itself promotes tumor growth without causing direct DNA damage. One of the mechanisms by which hypoxia contributes to tumor growth is the generation of genomic instability via down-regulation of high-fidelity DNA repair pathways. Here, we find that nickel exposure similarly leads to down-regulation of DNA repair proteins involved in homology-dependent DNA double-strand break repair (HDR) and mismatch repair (MMR) in tumorigenic and non-tumorigenic human lung cells. Functionally, nickel induces a defect in HDR capacity, as determined by plasmid-based host cell reactivation assays, persistence of ionizing radiation-induced DNA double-strand breaks and cellular hypersensitivity to ionizing radiation. Mechanistically, we find that nickel, in contrast to the metalloid arsenic, acutely induces transcriptional repression of HDR and MMR genes as part of a global transcriptional pattern similar to that seen with hypoxia. Finally, we find that exposure to low-dose nickel reduces the activity of the MLH1 promoter, but only arsenic leads to long-term MLH1 promoter silencing. Together, our data elucidate novel mechanisms of heavy metal carcinogenesis and contribute to our understanding of the influence of the microenvironment on the regulation of DNA repair pathways. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A 30-Year-Old Man with Three Primary Malignancies: A Case of Constitutional Mismatch Repair Deficiency

OpenAIRE

Rengifo-Cam, William; Jasperson, Kory; Garrido-Laguna, Ignacio; Colman, Howard; Scaife, Courtney; Samowitz, Wade; Samadder, N. Jewel

2017-01-01

Constitutional mismatch repair deficiency (CMMRD) is a devastating cancer predisposition syndrome for which clinical manifestations, genetic screening, and cancer prevention strategies are limited. We report a case of CMMRD presenting with metachronous colorectal cancer and brain cancer. Oncologists and gastroenterologists should be aware of the CMMRD syndrome as a rare cause of very early-onset colorectal cancer.

A 30-Year-Old Man with Three Primary Malignancies: A Case of Constitutional Mismatch Repair Deficiency.

Science.gov (United States)

Rengifo-Cam, William; Jasperson, Kory; Garrido-Laguna, Ignacio; Colman, Howard; Scaife, Courtney; Samowitz, Wade; Samadder, N Jewel

2017-01-01

Constitutional mismatch repair deficiency (CMMRD) is a devastating cancer predisposition syndrome for which clinical manifestations, genetic screening, and cancer prevention strategies are limited. We report a case of CMMRD presenting with metachronous colorectal cancer and brain cancer. Oncologists and gastroenterologists should be aware of the CMMRD syndrome as a rare cause of very early-onset colorectal cancer.

Schizosaccharomyces pombe MutSα and MutLα Maintain Stability of Tetra-Nucleotide Repeats and Msh3 of Hepta-Nucleotide Repeats

Directory of Open Access Journals (Sweden)

Desirée Villahermosa

2017-05-01

Full Text Available Defective mismatch repair (MMR in humans is associated with colon cancer and instability of microsatellites, that is, DNA sequences with one or several nucleotides repeated. Key factors of eukaryotic MMR are the heterodimers MutSα (Msh2-Msh6, which recognizes base-base mismatches and unpaired nucleotides in DNA, and MutLα (Mlh1-Pms1, which facilitates downstream steps. In addition, MutSβ (Msh2-Msh3 recognizes DNA loops of various sizes, although our previous data and the data presented here suggest that Msh3 of Schizosaccharomyces pombe does not play a role in MMR. To test microsatellite stability in S. pombe and hence DNA loop repair, we have inserted tetra-, penta-, and hepta-nucleotide repeats in the ade6 gene and determined their Ade+ reversion rates and spectra in wild type and various mutants. Our data indicate that loops with four unpaired nucleotides in the nascent and the template strand are the upper limit of MutSα- and MutLα-mediated MMR in S. pombe. Stability of hepta-nucleotide repeats requires Msh3 and Exo1 in MMR-independent processes as well as the DNA repair proteins Rad50, Rad51, and Rad2FEN1. Most strikingly, mutation rates in the double mutants msh3 exo1 and msh3 rad51 were decreased when compared to respective single mutants, indicating that Msh3 prevents error prone processes carried out by Exo1 and Rad51. We conclude that Msh3 has no obvious function in MMR in S. pombe, but contributes to DNA repeat stability in MMR-independent processes.

An intact Pms2 ATPase domain is not essential for male fertility

OpenAIRE

Fischer, Jared M; Dudley, Sandra; Miller, Ashleigh J; Liskay, R Michael

2015-01-01

The DNA mismatch repair (MMR) machinery in mammals plays critical roles in both mutation avoidance and spermatogenesis. Meiotic analysis of knockout mice of two different MMR genes, Mlh1 and Mlh3, revealed both male and female infertility associated with a defect in meiotic crossing over. In contrast, another MMR gene knockout, Pms2 (Pms2ko/ko), which contained a deletion of a portion of the ATPase domain, produced animals that were male sterile but female fertile. However, the meiotic phenot...

Gene expression signatures for colorectal cancer microsatellite status and HNPCC

DEFF Research Database (Denmark)

Kruhøffer, M; Jensen, J L; Laiho, P

2005-01-01

The majority of microsatellite instable (MSI) colorectal cancers are sporadic, but a subset belongs to the syndrome hereditary non-polyposis colorectal cancer (HNPCC). Microsatellite instability is caused by dysfunction of the mismatch repair (MMR) system that leads to a mutator phenotype, and MSI...... of 101 stage II and III colorectal cancers (34 MSI, 67 microsatellite stable (MSS)) using high-density oligonucleotide microarrays. From these data, we constructed a nine-gene signature capable of separating the mismatch repair proficient and deficient tumours. Subsequently, we demonstrated...... is correlated to prognosis and response to chemotherapy. Gene expression signatures as predictive markers are being developed for many cancers, and the identification of a signature for MMR deficiency would be of interest both clinically and biologically. To address this issue, we profiled the gene expression...

Functional analysis of HNPCC-related missense mutations in MSH2

International Nuclear Information System (INIS)

Luetzen, Anne; Wind, Niels de; Georgijevic, Dubravka; Nielsen, Finn Cilius; Rasmussen, Lene Juel

2008-01-01

Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germline mutations in the human DNA mismatch repair (MMR) genes, most frequently MSH2 and MLH1. The majority of HNPCC mutations cause truncations and thus loss of function of the affected polypeptide. However, a significant proportion of MMR mutations found in HNPCC patients are single amino acid substitutions and the functional consequences of many of these mutations in DNA repair are unclear. We have examined the consequences of seven MSH2 missense mutations found in HNPCC families by testing the MSH2 mutant proteins in functional assays as well as by generating equivalent missense mutations in Escherichia coli MutS and analyzing the phenotypes of these mutants. Here we show that two mutant proteins, MSH2-P622L and MSH2-C697F confer multiple biochemical defects, namely in mismatch binding, in vivo interaction with MSH6 and EXO1, and in nuclear localization in the cell. Mutation G674R, located in the ATP-binding region of MSH2, appears to confer resistance to ATP-dependent mismatch release. Mutations D167H and H639R show reduced mismatch binding. Results of in vivo experiments in E. coli with MutS mutants show that one additional mutant, equivalent of MSH2-A834T that do not show any defects in MSH2 assays, is repair deficient. In conclusion, all mutant proteins (except for MSH2-A305T) have defects; either in mismatch binding, ATP-release, mismatch repair activity, subcellular localization or protein-protein interactions

Functional analysis of HNPCC-related missense mutations in MSH2

Energy Technology Data Exchange (ETDEWEB)

Luetzen, Anne [Department of Science, Systems and Models, Roskilde University, DK-4000 Roskilde (Denmark); Wind, Niels de; Georgijevic, Dubravka [Department of Toxicogenetics, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden (Netherlands); Nielsen, Finn Cilius [Department of Clinical Biochemistry, Rigshospitalet, DK-2100 Copenhagen (Denmark); Rasmussen, Lene Juel [Department of Science, Systems and Models, Roskilde University, DK-4000 Roskilde (Denmark)], E-mail: ljr@ruc.dk

2008-10-14

Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germline mutations in the human DNA mismatch repair (MMR) genes, most frequently MSH2 and MLH1. The majority of HNPCC mutations cause truncations and thus loss of function of the affected polypeptide. However, a significant proportion of MMR mutations found in HNPCC patients are single amino acid substitutions and the functional consequences of many of these mutations in DNA repair are unclear. We have examined the consequences of seven MSH2 missense mutations found in HNPCC families by testing the MSH2 mutant proteins in functional assays as well as by generating equivalent missense mutations in Escherichia coli MutS and analyzing the phenotypes of these mutants. Here we show that two mutant proteins, MSH2-P622L and MSH2-C697F confer multiple biochemical defects, namely in mismatch binding, in vivo interaction with MSH6 and EXO1, and in nuclear localization in the cell. Mutation G674R, located in the ATP-binding region of MSH2, appears to confer resistance to ATP-dependent mismatch release. Mutations D167H and H639R show reduced mismatch binding. Results of in vivo experiments in E. coli with MutS mutants show that one additional mutant, equivalent of MSH2-A834T that do not show any defects in MSH2 assays, is repair deficient. In conclusion, all mutant proteins (except for MSH2-A305T) have defects; either in mismatch binding, ATP-release, mismatch repair activity, subcellular localization or protein-protein interactions.

Identification of a mismatch-specific endonuclease in hyperthermophilic Archaea

OpenAIRE

Ishino, Sonoko; Nishi, Yuki; Oda, Soichiro; Uemori, Takashi; Sagara, Takehiro; Takatsu, Nariaki; Yamagami, Takeshi; Shirai, Tsuyoshi; Ishino, Yoshizumi

2016-01-01

The common mismatch repair system processed by MutS and MutL and their homologs was identified in Bacteria and Eukarya. However, no evidence of a functional MutS/L homolog has been reported for archaeal organisms, and it is not known whether the mismatch repair system is conserved in Archaea. Here, we describe an endonuclease that cleaves double-stranded DNA containing a mismatched base pair, from the hyperthermophilic archaeon Pyrococcus furiosus. The corresponding gene revealed that the act...

Identification of Lynch syndrome mutations in the MLH1-PMS2 interface that disturb dimerization and mismatch repair.

Science.gov (United States)

Kosinski, Jan; Hinrichsen, Inga; Bujnicki, Janusz M; Friedhoff, Peter; Plotz, Guido

2010-08-01

Missense alterations of the mismatch repair gene MLH1 have been identified in a significant proportion of individuals suspected of having Lynch syndrome, a hereditary syndrome that predisposes for cancer of colon and endometrium. The pathogenicity of many of these alterations, however, is unclear. A number of MLH1 alterations are located in the C-terminal domain (CTD) of MLH1, which is responsible for constitutive dimerization with PMS2. We analyzed which alterations may result in pathogenic effects due to interference with dimerization. We used a structural model of CTD of MLH1-PMS2 heterodimer to select 19 MLH1 alterations located inside and outside two candidate dimerization interfaces in the MLH1-CTD. Three alterations (p.Gln542Leu, p.Leu749Pro, p.Tyr750X) caused decreased coexpression of PMS2, which is unstable in the absence of interaction with MLH1, suggesting that these alterations interfere with dimerization. All three alterations are located within the dimerization interface suggested by our model. They also compromised mismatch repair, suggesting that defects in dimerization abrogate repair and confirming that all three alterations are pathogenic. Additionally, we provided biochemical evidence that four alterations with uncertain pathogenicity (p.Ala586Pro, p.Leu636Pro, p.Thr662Pro, and p.Arg755Trp) are deleterious because of poor expression or poor repair efficiency, and confirm the deleterious effect of eight further alterations.

14-3-3 checkpoint regulatory proteins interact specifically with DNA repair protein human exonuclease 1 (hEXO1) via a semi-conserved motif

DEFF Research Database (Denmark)

Andersen, Sofie Dabros; Keijzers, Guido; Rampakakis, Emmanouil

2012-01-01

Human exonuclease 1 (hEXO1) acts directly in diverse DNA processing events, including replication, mismatch repair (MMR), and double strand break repair (DSBR), and it was also recently described to function as damage sensor and apoptosis inducer following DNA damage. In contrast, 14-3-3 proteins...... are specifically induced by replication inhibition leading to protein ubiquitination and degradation. We demonstrate direct and robust interaction between hEXO1 and six of the seven 14-3-3 isoforms in vitro, suggestive of a novel protein interaction network between DNA repair and cell cycle control. Binding...... and most likely a second unidentified binding motif. 14-3-3 associations do not appear to directly influence hEXO1 in vitro nuclease activity or in vitro DNA replication initiation. Moreover, specific phosphorylation variants, including hEXO1 S746A, are efficiently imported to the nucleus; to associate...

The dual nature of mismatch repair as antimutator and mutator

DEFF Research Database (Denmark)

Bak, Sara Thornby; Sakellariou, Despoina; Pena Diaz, Javier

2014-01-01

MMR also has detrimental effects; it promotes repeat expansions associated with neuromuscular and neurodegenerative diseases and may contribute to cancer/disease-related aberrant mutations and translocations. The reaction responsible for replication error correction has been the most thoroughly...

No significant role for beta tubulin mutations and mismatch repair defects in ovarian cancer resistance to paclitaxel/cisplatin

International Nuclear Information System (INIS)

Mesquita, Bárbara; Veiga, Isabel; Pereira, Deolinda; Tavares, Ana; Pinto, Isabel M; Pinto, Carla; Teixeira, Manuel R; Castedo, Sérgio

2005-01-01

The mechanisms of chemoresistance in ovarian cancer patients remain largely to be elucidated. Paclitaxel/cisplatin combination is the standard chemotherapeutic treatment for this disease, although some patients do not respond to therapy. Our goals were to investigate whether TUBB mutations and mismatch repair defects underlie paclitaxel and cisplatin resistance. Thirty-four patients with primary ovarian carcinomas (26 serous and eight clear cell carcinomas) treated with paclitaxel/cisplatin were analysed. TUBB exon 4 was analysed by nested PCR after a first round PCR using intronic primers. Microsatellite analysis was performed with the quasimonomorphic markers BAT 26 and BAT 34. Twenty-two of the 34 ovarian cancers (64.7%) presented residual tumour after surgery, seven of which (7/22; 31.8%) were shown to be chemoresistant (five serous and two clear cell tumours). Sequence analysis did not find any mutation in TUBB exon 4. Microsatellite instability was not detected in any of the ovarian carcinomas. We conclude that TUBB exon 4 mutations and mismatch repair defects do not play a significant role in paclitaxel/cisplatin resistance

A rare case of Crohn's ileitis in a patient with constitutional mismatch repair deficiency.

Science.gov (United States)

Kaimakliotis, Pavlos; Giardiello, Francis; Eze, Ogechukwu; Truta, Brindusa

2017-01-01

Constitutional mismatch repair deficiency (CMMRD), a variant of Lynch syndrome, is a rare disease characterized by café-au-lait spots, oligopolyposis, glioblastoma and lymphoma. A 24-year-old male, under surveillance for CMMRD, developed Crohn's ileitis after total colectomy with end ileostomy for colorectal cancer and failed to respond to oral corticosteroids. The patient underwent induction and maintenance of remission with vedolizumab infusions. We report the first patient with CMMRD developing Crohn's disease. The choice of immunosuppressive therapy in these patients is challenging and needs to be made according to their risk for malignancy.

Early onset of colorectal cancer in a 13-year-old girl with Lynch syndrome.

Science.gov (United States)

Ahn, Do Hee; Rho, Jung Hee; Tchah, Hann; Jeon, In-Sang

2016-01-01

Lynch syndrome is the most common inherited colon cancer syndrome. Patients with Lynch syndrome develop a range of cancers including colorectal cancer (CRC) and carry a mutation on one of the mismatched repair (MMR) genes. Although CRC usually occurs after the fourth decade in patients with Lynch syndrome harboring a heterozygous MMR gene mutation, it can occur in children with Lynch syndrome who have a compound heterozygous or homozygous MMR gene mutation. We report a case of CRC in a 13-year-old patient with Lynch syndrome and congenital heart disease. This patient had a heterozygous mutation in MLH1 (an MMR gene), but no compound MMR gene defects, and a K-RAS somatic mutation in the cancer cells.

DNA mismatch repair related gene expression as potential biomarkers to assess cadmium exposure in Arabidopsis seedlings

International Nuclear Information System (INIS)

Liu Wan; Zhou Qixing; Li Peijun; Gao Hairong; Han, Y.P.; Li, X.J.; Yang, Y.S.; Li Yanzhi

2009-01-01

In the current study, Arabidopsis seedlings were hydroponically grown on MS media containing cadmium (Cd) of 0-2.0 mg L -1 for 60 h of treatment. Gene expression profiles were used to relate exposure to Cd with some altered biological responses and/or specific growth effects. RT-PCR analysis was used to quantitate mRNA expression for seven genes known to be involved in DNA mismatch repair (MMR) system and cell division. Results indicated that Cd concentrations of 0.25-2.0 mg L -1 cause increased total soluble protein levels in shoots of Arabidopsis seedlings in an inverted U-shaped dose-response manner. Exposure to 0.25 and 0.5 mg L -1 of Cd dramatically induced expression of four genes (i.e. proliferating cell nuclear antigen 2 (atPCNA 2), MutL1 homolog (atMLH1), MutS 2 homolog (atMSH2) and atMSH3) and five genes (i.e. atPCNA1,2, atMLH1 and atMSH2,7), respectively, in shoots of Arabidopsis seedlings; Exposure to 1.0 mg L -1 of Cd significantly elevated expression of only two genes (atMSH6,7), but caused prominent inhibition in expression of three genes (atPCNA2, atMLH1 and atMSH3) in shoots of Arabidopsis seedlings. The expression alterations of the above genes were independent of any biological effects such as survival, fresh weight and chlorophyll level of shoots. However, shoots of Arabidopsis seedlings exposed to 2.0 mg L -1 of Cd exhibited statistically prominent repression in expression of these seven genes, and showed incipient reduction of fresh weight and chlorophyll level. This research provides data concerning sensitivity of expression profiles of atMLH1, atMSH2,3,6,7 and atPCNA1,2 genes in Arabidopsis seedlings to Cd exposure, as well as the potential use of these gene expression patterns as representative molecular biomarkers indicative of Cd exposure and related biological effects.

DNA repair in neurons: So if they don't divide what's to repair?

International Nuclear Information System (INIS)

Fishel, Melissa L.; Vasko, Michael R.; Kelley, Mark R.

2007-01-01

Neuronal DNA repair remains one of the most exciting areas for investigation, particularly as a means to compare the DNA repair response in mitotic (cancer) vs. post-mitotic (neuronal) cells. In addition, the role of DNA repair in neuronal cell survival and response to aging and environmental insults is of particular interest. DNA damage caused by reactive oxygen species (ROS) such as generated by mitochondrial respiration includes altered bases, abasic sites, and single- and double-strand breaks which can be prevented by the DNA base excision repair (BER) pathway. Oxidative stress accumulates in the DNA of the human brain over time especially in the mitochondrial DNA (mtDNA) and is proposed to play a critical role in aging and in the pathogenesis of several neurological disorders including Parkinson's disease, ALS, and Alzheimer's diseases. Because DNA damage accumulates in the mtDNA more than nuclear DNA, there is increased interest in DNA repair pathways and the consequence of DNA damage in the mitochondria of neurons. The type of damage that is most likely to occur in neuronal cells is oxidative DNA damage which is primarily removed by the BER pathway. Following the notion that the bulk of neuronal DNA damage is acquired by oxidative DNA damage and ROS, the BER pathway is a likely area of focus for neuronal studies of DNA repair. BER variations in brain aging and pathology in various brain regions and tissues are presented. Therefore, the BER pathway is discussed in greater detail in this review than other repair pathways. Other repair pathways including direct reversal, nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination and non-homologous end joining are also discussed. Finally, there is a growing interest in the role that DNA repair pathways play in the clinical arena as they relate to the neurotoxicity and neuropathy associated with cancer treatments. Among the numerous side effects of cancer treatments, major clinical effects

Identification of a mismatch-specific endonuclease in hyperthermophilic Archaea.

Science.gov (United States)

Ishino, Sonoko; Nishi, Yuki; Oda, Soichiro; Uemori, Takashi; Sagara, Takehiro; Takatsu, Nariaki; Yamagami, Takeshi; Shirai, Tsuyoshi; Ishino, Yoshizumi

2016-04-20

The common mismatch repair system processed by MutS and MutL and their homologs was identified in Bacteria and Eukarya. However, no evidence of a functional MutS/L homolog has been reported for archaeal organisms, and it is not known whether the mismatch repair system is conserved in Archaea. Here, we describe an endonuclease that cleaves double-stranded DNA containing a mismatched base pair, from the hyperthermophilic archaeon Pyrococcus furiosus The corresponding gene revealed that the activity originates from PF0012, and we named this enzyme Endonuclease MS (EndoMS) as the mismatch-specific Endonuclease. The sequence similarity suggested that EndoMS is the ortholog of NucS isolated from Pyrococcus abyssi, published previously. Biochemical characterizations of the EndoMS homolog from Thermococcus kodakarensis clearly showed that EndoMS specifically cleaves both strands of double-stranded DNA into 5'-protruding forms, with the mismatched base pair in the central position. EndoMS cleaves G/T, G/G, T/T, T/C and A/G mismatches, with a more preference for G/T, G/G and T/T, but has very little or no effect on C/C, A/C and A/A mismatches. The discovery of this endonuclease suggests the existence of a novel mismatch repair process, initiated by the double-strand break generated by the EndoMS endonuclease, in Archaea and some Bacteria. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Telomeres and genomic damage repair. Their implication in human pathology

International Nuclear Information System (INIS)

Perez, Maria del R.; Dubner, Diana; Michelin, Severino; Gisone, Pablo; Carosella, Edgardo D.

2002-01-01

Telomeres, functional complexed that protect eukaryotic chromosome ends, participate in the regulation of cell proliferation and could play a role in the stabilization of genomic regions in response to genotoxic stress. Their significance in human pathology becomes evident in several diseases sharing genomic instability as a common trait, in which alterations of the telomere metabolism have been demonstrated. Many of them are also associated with hypersensitivity to ionizing radiation and cancer susceptibility. Besides the specific proteins belonging to the telomeric complex, other proteins involved in the DNA repair machinery, such as ATM, BRCA1, BRCA2, PARP/tankyrase system, DNA-PK and RAD50-MRE11-NBS1 complexes, are closely related with the telomere. This suggests that the telomere sequesters DNA repair proteins for its own structure maintenance, with could also be released toward damaged sites in the genomic DNA. This communication describes essential aspects of telomere structure and function and their links with homologous recombination, non-homologous end-joining (NHEJ), V(D)J system and mismatch-repair (MMR). Several pathological conditions exhibiting alterations in some of these mechanisms are also considered. The cell response to ionizing radiation and its relationship with the telomeric metabolism is particularly taken into account as a model for studying genotoxicity. (author)

Diagnostic criteria for constitutional mismatch repair deficiency syndrome: suggestions of the European consortium 'care for CMMRD' (C4CMMRD).

Science.gov (United States)

Wimmer, Katharina; Kratz, Christian P; Vasen, Hans F A; Caron, Olivier; Colas, Chrystelle; Entz-Werle, Natacha; Gerdes, Anne-Marie; Goldberg, Yael; Ilencikova, Denisa; Muleris, Martine; Duval, Alex; Lavoine, Noémie; Ruiz-Ponte, Clara; Slavc, Irene; Burkhardt, Brigit; Brugieres, Laurence

2014-06-01

Constitutional mismatch repair deficiency (CMMRD) syndrome is a distinct childhood cancer predisposition syndrome that results from biallelic germline mutations in one of the four MMR genes, MLH1, MSH2, MSH6 or PMS2. The tumour spectrum is very broad, including mainly haematological, brain and intestinal tract tumours. Patients show a variety of non-malignant features that are indicative of CMMRD. However, currently no criteria that should entail diagnostic evaluation of CMMRD exist. We present a three-point scoring system for the suspected diagnosis CMMRD in a paediatric/young adult cancer patient. Tumours highly specific for CMMRD syndrome are assigned three points, malignancies overrepresented in CMMRD two points and all other malignancies one point. According to their specificity for CMMRD and their frequency in the general population, additional features are weighted with 1-2 points. They include multiple hyperpigmented and hypopigmented skin areas, brain malformations, pilomatricomas, a second childhood malignancy, a Lynch syndrome (LS)-associated tumour in a relative and parental consanguinity. According to the scoring system, CMMRD should be suspected in any cancer patient who reaches a minimum of three points by adding the points of the malignancy and the additional features. The diagnostic steps to confirm or refute the suspected diagnosis are outlined. We expect that application of the suggested strategy for CMMRD diagnosis will increase the number of patients being identified at the time when they develop their first tumour. This will allow adjustment of the treatment modalities, offering surveillance strategies for second malignancies and appropriate counselling of the entire family. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Role of oxidative DNA damage in genome instability and cancer

International Nuclear Information System (INIS)

Bignami, M.; Kunkel, T.

2009-01-01

Inactivation of mismatch repair (MMR) is associated with a dramatic genomic instability that is observed experimentally as a mutator phenotype and micro satellite instability (MSI). It has been implicit that the massive genetic instability in MMR defective cells simply reflects the accumulation of spontaneous DNA polymerase errors during DNA replication. We recently identified oxidation damage, a common threat to DNA integrity to which purines are very susceptible, as an important cofactor in this genetic instability

Gastric Medullary Carcinoma with Sporadic Mismatch Repair Deficiency and a TP53 R273C Mutation: An Unusual Case with Wild-Type BRAF

Directory of Open Access Journals (Sweden)

Brett M. Lowenthal

2017-01-01

Full Text Available Medullary carcinoma has long been recognized as a subtype of colorectal cancer associated with microsatellite instability and Lynch syndrome. Gastric medullary carcinoma is a very rare neoplasm. We report a 67-year-old male who presented with a solitary gastric mass. Total gastrectomy revealed a well-demarcated, poorly differentiated carcinoma with an organoid growth pattern, pushing borders, and abundant peritumoral lymphocytic response. The prior cytology was cellular with immunohistochemical panel consistent with upper gastrointestinal/pancreaticobiliary origin. Overall, the histopathologic findings were consistent with gastric medullary carcinoma. A mismatch repair panel revealed a mismatch repair protein deficient tumor with loss of MLH1 and PMS2 expression. BRAF V600E immunostain (VE1 and BRAF molecular testing were negative, indicating a wild-type gene. Tumor sequencing of MLH1 demonstrated a wild-type gene, while our molecular panel identified TP53 c.817C>T (p.R273C mutation. These findings were compatible with a sporadic tumor. Given that morphologically identical medullary tumors often occur in Lynch syndrome, it is possible that mismatch repair loss is an early event in sporadic tumors with p53 mutation being a late event. Despite having wild-type BRAF, this tumor is sporadic and unrelated to Lynch syndrome. This case report demonstrates that coordinate ancillary studies are needed to resolve sporadic versus hereditary rare tumors.

Stripped-down DNA repair in a highly reduced parasite

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Fast Naomi M

2007-03-01

Full Text Available Abstract Background Encephalitozoon cuniculi is a member of a distinctive group of single-celled parasitic eukaryotes called microsporidia, which are closely related to fungi. Some of these organisms, including E. cuniculi, also have uniquely small genomes that are within the prokaryotic range. Thus, E. cuniculi has undergone a massive genome reduction which has resulted in a loss of genes from diverse biological pathways, including those that act in DNA repair. DNA repair is essential to any living cell. A loss of these mechanisms invariably results in accumulation of mutations and/or cell death. Six major pathways of DNA repair in eukaryotes include: non-homologous end joining (NHEJ, homologous recombination repair (HRR, mismatch repair (MMR, nucleotide excision repair (NER, base excision repair (BER and methyltransferase repair. DNA polymerases are also critical players in DNA repair processes. Given the close relationship between microsporidia and fungi, the repair mechanisms present in E. cuniculi were compared to those of the yeast Saccharomyces cerevisiae to ascertain how the process of genome reduction has affected the DNA repair pathways. Results E. cuniculi lacks 16 (plus another 6 potential absences of the 56 DNA repair genes sought via BLASTP and PSI-BLAST searches. Six of 14 DNA polymerases or polymerase subunits are also absent in E. cuniculi. All of these genes are relatively well conserved within eukaryotes. The absence of genes is not distributed equally among the different repair pathways; some pathways lack only one protein, while there is a striking absence of many proteins that are components of both double strand break repair pathways. All specialized repair polymerases are also absent. Conclusion Given the large number of DNA repair genes that are absent from the double strand break repair pathways, E. cuniculi is a prime candidate for the study of double strand break repair with minimal machinery. Strikingly, all of the

A novel germline POLE mutation causes an early onset cancer prone syndrome mimicking constitutional mismatch repair deficiency.

Science.gov (United States)

Wimmer, Katharina; Beilken, Andreas; Nustede, Rainer; Ripperger, Tim; Lamottke, Britta; Ure, Benno; Steinmann, Diana; Reineke-Plaass, Tanja; Lehmann, Ulrich; Zschocke, Johannes; Valle, Laura; Fauth, Christine; Kratz, Christian P

2017-01-01

In a 14-year-old boy with polyposis and rectosigmoid carcinoma, we identified a novel POLE germline mutation, p.(Val411Leu), previously found as recurrent somatic mutation in 'ultramutated' sporadic cancers. This is the youngest reported cancer patient with polymerase proofreading-associated polyposis indicating that POLE mutation p.(Val411Leu) may confer a more severe phenotype than previously reported POLE and POLD1 germline mutations. The patient had multiple café-au-lait macules and a pilomatricoma mimicking the clinical phenotype of constitutional mismatch repair deficiency. We hypothesize that these skin features may be common to different types of constitutional DNA repair defects associated with polyposis and early-onset cancer.

Synchronous glioblastoma and medulloblastoma in a child with mismatch repair mutation.

Science.gov (United States)

Amayiri, Nisreen; Al-Hussaini, Maysa; Swaidan, Maisa; Jaradat, Imad; Qandeel, Monther; Tabori, Uri; Hawkins, Cynthia; Musharbash, Awni; Alsaad, Khulood; Bouffet, Eric

2016-03-01

Synchronous primary malignant brain tumors are rare. We present a 5-year-old boy with synchronous glioblastoma and medulloblastoma. Both tumor samples had positive p53 stain and loss of PMS2 and MLH1 stains. The child had multiple café au lait spots and a significant family history of cancer. After subtotal resection of both tumors, he received craniospinal radiation with concomitant temozolomide followed by chemotherapy, alternating cycles of cisplatin/lomustine/vincristine with temozolomide. Then, he started maintenance treatment with cis-retinoic acid (100 mg/m(2)/day for 21 days). He remained asymptomatic for 34 months despite a follow-up brain MRI consistent with glioblastoma relapse 9 months before his death. Cis-retinoic acid may have contributed to prolong survival in this child with a probable biallelic mismatch repair syndrome.

TaMSH7: A cereal mismatch repair gene that affects fertility in transgenic barley (Hordeum vulgare L.

Directory of Open Access Journals (Sweden)

Langridge Peter

2007-12-01

Full Text Available Abstract Background Chromosome pairing, recombination and DNA repair are essential processes during meiosis in sexually reproducing organisms. Investigating the bread wheat (Triticum aestivum L. Ph2 (Pairing homoeologous locus has identified numerous candidate genes that may have a role in controlling such processes, including TaMSH7, a plant specific member of the DNA mismatch repair family. Results Sequencing of the three MSH7 genes, located on the short arms of wheat chromosomes 3A, 3B and 3D, has revealed no significant sequence divergence at the amino acid level suggesting conservation of function across the homoeogroups. Functional analysis of MSH7 through the use of RNAi loss-of-function transgenics was undertaken in diploid barley (Hordeum vulgare L.. Quantitative real-time PCR revealed several T0 lines with reduced MSH7 expression. Positive segregants from two T1 lines studied in detail showed reduced MSH7 expression when compared to transformed controls and null segregants. Expression of MSH6, another member of the mismatch repair family which is most closely related to the MSH7 gene, was not significantly reduced in these lines. In both T1 lines, reduced seed set in positive segregants was observed. Conclusion Results presented here indicate, for the first time, a distinct functional role for MSH7 in vivo and show that expression of this gene is necessary for wild-type levels of fertility. These observations suggest that MSH7 has an important function during meiosis and as such remains a candidate for Ph2.

Paediatric intestinal cancer and polyposis due to bi-allelic PMS2 mutations : Case series, review and follow-up guidelines

NARCIS (Netherlands)

Herkert, Johanna C; Niessen, Renée C; Olderode-Berends, Maria J W; Veenstra-Knol, Hermine E; Vos, Yvonne J; van der Klift, Heleen M; Scheenstra, Rene; Tops, Carli M J; Karrenbeld, Arend; Peters, Frans T M; Hofstra, Robert M W; Kleibeuker, Jan H; Sijmons, Rolf H

BACKGROUND: Bi-allelic germline mutations of one of the DNA mismatch repair genes, so far predominantly found in PMS2, cause constitutional MMR-deficiency syndrome. This rare disorder is characterised by paediatric intestinal cancer and other malignancies. We report the clinical, immunohistochemical

Thymidine selectively enhances growth suppressive effects of camptothecin/irinotecan in MSI+ cells and tumors containing a mutation of MRE11

DEFF Research Database (Denmark)

Rodriguez, Rene; Hansen, Lasse Tengbjerg; Phear, Geraldine

2008-01-01

to exploit the altered response of mismatch repair (MMR)-deficient colon cancer cells and tumors to camptothecin or irinotecan and thymidine by combining them to improve therapeutic response. EXPERIMENTAL DESIGN: A panel of colon cancer cell lines was assayed for response to camptothecin...

Ovarian cancer at young age: the contribution of mismatch-repair defects in a population-based series of epithelial ovarian

DEFF Research Database (Denmark)

Domanska, K; Malander, S; Måsbäck, A

2007-01-01

and endometrioid cancers were overrepresented and were diagnosed in 27% and 16% of the tumors, respectively. Immunostaining using antibodies against MLH1, PMS2, MSH2, and MSH6 was used to assess the mismatch-repair status and revealed loss of expression of MLH1/PMS2 in two cases, loss of MSH2/MSH6 in one case...

Induction d'un processus d'instabilité des microsatellites du génome dans des modèles murin et cellulaire : intérêt physiopathologique et clinique

OpenAIRE

Bodo , Sahra

2014-01-01

Inactivation of the MMR (mismatch repair) system promotes the oncogenic process of microsatellite instability (MSI). During my PhD, I firstly investigated the role of azathioprine (Aza) in the induction of MSI tumors in mice. Epidemiological studies reported a correlation between the occurrence of late MSI cancers in humans and long-term treatment with this immunosuppressant whose cytotoxicity was shown in vitro to be mediated by MMR activity. Using a dose-response study, I observed the occur...

DNA repair in neurons: So if they don't divide what's to repair?

Energy Technology Data Exchange (ETDEWEB)

Fishel, Melissa L. [Department of Pediatrics (Section of Hematology/Oncology), Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 W. Walnut, Room 302C, Indianapolis, IN 46202 (United States); Vasko, Michael R. [Department of Pharmacology and Toxicology, Indiana University School of Medicine, 1044 W. Walnut St., Indianapolis, IN 46202 (United States); Kelley, Mark R. [Department of Pediatrics (Section of Hematology/Oncology), Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 W. Walnut, Room 302C, Indianapolis, IN 46202 (United States) and Department of Pharmacology and Toxicology, Indiana University School of Medicine, 1044 W. Walnut St., Indianapolis, IN 46202 (United States) and Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 1044 W. Walnut, Room 302C, Indianapolis, IN 46202 (United States)]. E-mail: mkelley@iupui.edu

2007-01-03

Neuronal DNA repair remains one of the most exciting areas for investigation, particularly as a means to compare the DNA repair response in mitotic (cancer) vs. post-mitotic (neuronal) cells. In addition, the role of DNA repair in neuronal cell survival and response to aging and environmental insults is of particular interest. DNA damage caused by reactive oxygen species (ROS) such as generated by mitochondrial respiration includes altered bases, abasic sites, and single- and double-strand breaks which can be prevented by the DNA base excision repair (BER) pathway. Oxidative stress accumulates in the DNA of the human brain over time especially in the mitochondrial DNA (mtDNA) and is proposed to play a critical role in aging and in the pathogenesis of several neurological disorders including Parkinson's disease, ALS, and Alzheimer's diseases. Because DNA damage accumulates in the mtDNA more than nuclear DNA, there is increased interest in DNA repair pathways and the consequence of DNA damage in the mitochondria of neurons. The type of damage that is most likely to occur in neuronal cells is oxidative DNA damage which is primarily removed by the BER pathway. Following the notion that the bulk of neuronal DNA damage is acquired by oxidative DNA damage and ROS, the BER pathway is a likely area of focus for neuronal studies of DNA repair. BER variations in brain aging and pathology in various brain regions and tissues are presented. Therefore, the BER pathway is discussed in greater detail in this review than other repair pathways. Other repair pathways including direct reversal, nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination and non-homologous end joining are also discussed. Finally, there is a growing interest in the role that DNA repair pathways play in the clinical arena as they relate to the neurotoxicity and neuropathy associated with cancer treatments. Among the numerous side effects of cancer treatments, major

Comprehensive Mutation Analysis of PMS2 in a Large Cohort of Probands Suspected of Lynch Syndrome or Constitutional Mismatch Repair Deficiency Syndrome

NARCIS (Netherlands)

Klift, H.M. van der; Mensenkamp, A.R.; Drost, M.; Bik, E.C.; Vos, Y.J.; Gille, H.J.; Redeker, B.E.; Tiersma, Y.; Zonneveld, J.B.; Garcia, E.G.; Letteboer, T.G.; Olderode-Berends, M.J.; Hest, L.P. van; Os, T.A. van; Verhoef, S.; Wagner, A.; Asperen, C.J. van; Broeke, S.W. ten; Hes, F.J.; Wind, N. de; Nielsen, M.; Devilee, P.; Ligtenberg, M.J.L.; Wijnen, J.T.; Tops, C.M.

2016-01-01

Monoallelic PMS2 germline mutations cause 5%-15% of Lynch syndrome, a midlife cancer predisposition, whereas biallelic PMS2 mutations cause approximately 60% of constitutional mismatch repair deficiency (CMMRD), a rare childhood cancer syndrome. Recently improved DNA- and RNA-based strategies are

Comprehensive Mutation Analysis of PMS2 in a Large Cohort of Probands Suspected of Lynch Syndrome or Constitutional Mismatch Repair Deficiency Syndrome

NARCIS (Netherlands)

van der Klift, Heleen M.; Mensenkamp, Arjen R.; Drost, Mark; Bik, Elsa C.; Vos, Yvonne J.; Gille, Hans J. J. P.; Redeker, Bert E. J. W.; Tiersma, Yvonne; Zonneveld, Jose B. M.; Garcia, Encarna Gomez; Letteboer, Tom G. W.; Olderode-Berends, Maran J. W.; van Hest, Liselotte P.; van Os, Theo A.; Verhoef, Senno; Wagner, Anja; van Asperen, Christi J.; ten Broeke, Sanne W.; Hes, Frederik J.; de Wind, Niels; Nielsen, Maartje; Devilee, Peter; Ligtenberg, Marjolijn J. L.; Wijnen, Juul T.; Tops, Carli M. J.

Monoallelic PMS2 germline mutations cause 5%-15% of Lynch syndrome, a midlife cancer predisposition, whereas biallelic PMS2 mutations cause approximately 60% of constitutional mismatch repair deficiency (CMMRD), a rare childhood cancer syndrome. Recently improved DNA- and RNA-based strategies are

MSH2 mutation carriers are at higher risk of cancer than MLH1 mutation carriers : A study of hereditary nonpolyposis colorectal cancer families

NARCIS (Netherlands)

Vasen, HFA; Stormorken, A; Menko, FH; Nagengast, FM; Kleibeuker, JH; Griffioen, G; Taal, BG; Moller, P; Wijnen, JT

2001-01-01

Purpose: Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disease characterized by the clustering of colorectal cancer, endometrial cancer, and various other cancers. The disease is caused by mutations in DNA-mismatch-repair (MMR) genes, most frequently in MLH1, MSH2, and

Functional analysis of HNPCC-related missense mutations in MSH2

DEFF Research Database (Denmark)

Lützen, Anne; de Wind, Niels; Georgijevic, Dubravka

2008-01-01

Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germline mutations in the human DNA mismatch repair (MMR) genes, most frequently MSH2 and MLH1. The majority of HNPCC mutations cause truncations and thus loss of function of the affected polypeptide. However, a significant...

MSH2 mutation carriers are at higher risk of cancer than MLH1 mutation carriers: a study of hereditary nonpolyposis colorectal cancer families.

NARCIS (Netherlands)

Vasen, H.F.; Stormorken, A.; Menko, F.H.; Nagengast, F.M.; Kleibeuker, J.H.; Griffioen, G.; Taal, B.G.; Moller, P.; Wijnen, J.T.

2001-01-01

PURPOSE: Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disease characterized by the clustering of colorectal cancer, endometrial cancer, and various other cancers. The disease is caused by mutations in DNA-mismatch-repair (MMR) genes, most frequently in MLH1, MSH2, and

Transient overexpression of DNA adenine methylase enables efficient and mobile genome engineering with reduced off-target effects

DEFF Research Database (Denmark)

Lennen, Rebecca; Nilsson Wallin, Annika; Pedersen, Margit

2016-01-01

Homologous recombination of single-stranded oligonucleotides is a highly efficient process for introducing precise mutations into the genome of E. coli and other organisms when mismatch repair (MMR) is disabled. This can result in the rapid accumulation of off-target mutations that can mask desir...

Surveillance for urinary tract cancer in Lynch syndrome

DEFF Research Database (Denmark)

Bernstein, Inge Thomsen; Myrhøj, Torben

2013-01-01

Hereditary non-polyposis colorectal cancer (HNPCC) is an inherited multiorgan cancer syndrome, which when caused by a germline mutation in the mismatch repair (MMR) genes is known as Lynch syndrome (LS). Mutation carriers are at risk for developing cancers primarily in the colon, rectum...

Expression of DNA mismatch repair proteins in transformed non-Hodgkin's lymphoma: relationship to smoking

DEFF Research Database (Denmark)

Nandi, S; Yu, J; Reinert, Line

2006-01-01

leukemia (CLL/SLL), that have transformed to diffuse-large B-cell lymphoma (DLBCL). We correlated the presence or absence of DNA-mismatch repair enzymes by immunostaining as well as the p53 status to smoking history. Of all patients (n = 30), 37% showed negative immunostaining of MLH1, 16% showed negative...... for either MLH1 or MSH2 was 2.2 times higher in smokers than non-smokers (relative risk = 2.2041, 95% confidence interval: 0.89714, 5.41491). No direct correlation was found between smoking and the mutations in the p53 gene. These results suggest that cigarette smoking may play a role in the development...

Role of DNA mismatch repair and p53 in signaling induction of apoptosis by alkylating agents

OpenAIRE

Hickman, Mark J.; Samson, Leona D.

1999-01-01

All cells are unavoidably exposed to chemicals that can alkylate DNA to form genotoxic damage. Among the various DNA lesions formed, O6-alkylguanine lesions can be highly cytotoxic, and we recently demonstrated that O6-methylguanine (O6MeG) and O6-chloroethylguanine (O6CEG) specifically initiate apoptosis in hamster cells. Here we show, in both hamster and human cells, that the MutSα branch of the DNA mismatch repair pathway (but not the MutSβ branch) is absolutely required for signaling the ...

Mlh1-Mlh3, a Meiotic Crossover and DNA Mismatch Repair Factor, Is a Msh2-Msh3-stimulated Endonuclease*

Science.gov (United States)

Rogacheva, Maria V.; Manhart, Carol M.; Chen, Cheng; Guarne, Alba; Surtees, Jennifer; Alani, Eric

2014-01-01

Crossing over between homologous chromosomes is initiated in meiotic prophase in most sexually reproducing organisms by the appearance of programmed double strand breaks throughout the genome. In Saccharomyces cerevisiae the double-strand breaks are resected to form three prime single-strand tails that primarily invade complementary sequences in unbroken homologs. These invasion intermediates are converted into double Holliday junctions and then resolved into crossovers that facilitate homolog segregation during Meiosis I. Work in yeast suggests that Msh4-Msh5 stabilizes invasion intermediates and double Holliday junctions, which are resolved into crossovers in steps requiring Sgs1 helicase, Exo1, and a putative endonuclease activity encoded by the DNA mismatch repair factor Mlh1-Mlh3. We purified Mlh1-Mlh3 and showed that it is a metal-dependent and Msh2-Msh3-stimulated endonuclease that makes single-strand breaks in supercoiled DNA. These observations support a direct role for an Mlh1-Mlh3 endonuclease activity in resolving recombination intermediates and in DNA mismatch repair. PMID:24403070

A rhodium(III) complex for high-affinity DNA base-pair mismatch recognition

Science.gov (United States)

Junicke, Henrik; Hart, Jonathan R.; Kisko, Jennifer; Glebov, Oleg; Kirsch, Ilan R.; Barton, Jacqueline K.

2003-01-01

A rhodium(III) complex, rac-[Rh(bpy)2phzi]3+ (bpy, 2,2′-bipyridine; phzi, benzo[a]phenazine-5,6-quinone diimine) has been designed as a sterically demanding intercalator targeted to destabilized mismatched sites in double-helical DNA. The complex is readily synthesized by condensation of the phenazine quinone with the corresponding diammine complex. Upon photoactivation, the complex promotes direct strand scission at single-base mismatch sites within the DNA duplex. As with the parent mismatch-specific reagent, [Rh(bpy)2(chrysi)]3+ [chrysene-5,6-quinone diimine (chrysi)], mismatch selectivity depends on the helix destabilization associated with mispairing. Unlike the parent chrysi complex, the phzi analogue binds and cleaves with high affinity and efficiency. The specific binding constants for CA, CC, and CT mismatches within a 31-mer oligonucleotide duplex are 0.3, 1, and 6 × 107 M−1, respectively; site-specific photocleavage is evident at nanomolar concentrations. Moreover, the specificity, defined as the ratio in binding affinities for mispaired vs. well paired sites, is maintained. The increase in affinity is attributed to greater stability in the mismatched site associated with stacking by the heterocyclic aromatic ligand. The high-affinity complex is also applied in the differential cleavage of DNA obtained from cell lines deficient in mismatch repair vs. those proficient in mismatch repair. Agreement is found between photocleavage by the mismatch-specific probes and deficiency in mismatch repair. This mismatch-specific targeting, therefore, offers a potential strategy for new chemotherapeutic design. PMID:12610209

A reversible histone H3 acetylation cooperates with mismatch repair and replicative polymerases in maintaining genome stability.

Directory of Open Access Journals (Sweden)

Lyudmila Y Kadyrova

2013-10-01

Full Text Available Mutations are a major driving force of evolution and genetic disease. In eukaryotes, mutations are produced in the chromatin environment, but the impact of chromatin on mutagenesis is poorly understood. Previous studies have determined that in yeast Saccharomyces cerevisiae, Rtt109-dependent acetylation of histone H3 on K56 is an abundant modification that is introduced in chromatin in S phase and removed by Hst3 and Hst4 in G2/M. We show here that the chromatin deacetylation on histone H3 K56 by Hst3 and Hst4 is required for the suppression of spontaneous gross chromosomal rearrangements, base substitutions, 1-bp insertions/deletions, and complex mutations. The rate of base substitutions in hst3Δ hst4Δ is similar to that in isogenic mismatch repair-deficient msh2Δ mutant. We also provide evidence that H3 K56 acetylation by Rtt109 is important for safeguarding DNA from small insertions/deletions and complex mutations. Furthermore, we reveal that both the deacetylation and acetylation on histone H3 K56 are involved in mutation avoidance mechanisms that cooperate with mismatch repair and the proofreading activities of replicative DNA polymerases in suppressing spontaneous mutagenesis. Our results suggest that cyclic acetylation and deacetylation of chromatin contribute to replication fidelity and play important roles in the protection of nuclear DNA from diverse spontaneous mutations.

First report of a de novo germline mutation in the MLH1 gene

NARCIS (Netherlands)

Stulp, Rein P; Vos, Yvonne J; Mol, Bart; Karrenbeld, Arend; de Raad, Monique; van der Mijle, Huub J C; Sijmons, Rolf H

2006-01-01

Hereditary non-polyposis colorectal carcinoma (HNPCC) is an autosomal dominant disorder associated with colorectal and endometrial cancer and a range of other tumor types. Germline mutations in the DNA mismatch repair (MMR) genes, particularly MLH1, MSH2, and MSH6, underlie this disorder. The vast

Gene variants of unknown clinical significance in Lynch syndrome. An introduction for clinicians

NARCIS (Netherlands)

Sijmons, Rolf H.; Greenblatt, Marc S.; Genuardi, Maurizio

Clinicians referring patients for genetic testing for Lynch syndrome will sooner or later receive results for DNA Mismatch Repair (MMR) genes reporting DNA changes that are unclear from a clinical point of view. These changes are referred to as variants of unknown, or unclear, clinical significance

Inflammatory potential of the diet and colorectal tumor risk in persons with Lynch syndrome

NARCIS (Netherlands)

Brouwer, Jesca G.M.; Makama, Maureen; Woudenbergh, Van Geertruida J.; Vasen, Hans F.A.; Nagengast, Fokko M.; Kleibeuker, Jan H.; Kampman, Ellen; Duijnhoven, Van Fränzel J.B.

2017-01-01

Background: Persons with Lynch syndrome (LS) have high lifetime risk of developing colorectal tumors (CRTs) because of a germline mutation in one of their mismatch repair (MMR) genes. An important process in the development of CRTs is inflammation, which has been shown to be modulated by diet.

Cancer risk in hereditary nonpolyposis colorectal cancer due to MSH6 mutations: impact on counseling and surveillance

NARCIS (Netherlands)

Hendriks, Yvonne M. C.; Wagner, Anja; Morreau, Hans; Menko, Fred; Stormorken, Astrid; Quehenberger, Franz; Sandkuijl, Lodewijk; Møller, Pal; Genuardi, Maurizio; van Houwelingen, Hans; Tops, Carli; van Puijenbroek, Marjo; Verkuijlen, Paul; Kenter, Gemma; van Mil, Anneke; Meijers-Heijboer, Hanne; Tan, Gita B.; Breuning, Martijn H.; Fodde, Riccardo; Wijnen, Juul Th; Bröcker-Vriends, Annette H. J. T.; Vasen, Hans

2004-01-01

BACKGROUND & AIMS: Hereditary nonpolyposis colorectal carcinoma (HNPCC) is caused by a mutated mismatch repair (MMR) gene. The aim of our study was to determine the cumulative risk of developing cancer in a large series of MSH6 mutation carriers. METHODS: Mutation analysis was performed in 20

Lynch syndrome caused by germline PMS2 mutations: delineating the cancer risk

NARCIS (Netherlands)

Broeke, S.W. ten; Brohet, R.M.; Tops, C.M.; Klift, H.M. van der; Velthuizen, M.E.; Bernstein, I.; Capella Munar, G.; Garcia, E.; Hoogerbrugge, N.; Letteboer, T.G.; Menko, F.H.; Lindblom, A.; Mensenkamp, A.R.; Moller, P.; Os, T.A. van; Rahner, N.; Redeker, B.J.; Sijmons, R.H.; Spruijt, L.; Suerink, M.; Vos, Y.J.; Wagner, A.; Hes, F.J.; Vasen, H.F.A.; Nielsen, M.; Wijnen, J.T.

2015-01-01

PURPOSE: The clinical consequences of PMS2 germline mutations are poorly understood compared with other Lynch-associated mismatch repair gene (MMR) mutations. The aim of this European cohort study was to define the cancer risk faced by PMS2 mutation carriers. METHODS: Data were collected from 98

Pembrolizumab, Capecitabine, and Radiation Therapy in Treating Patients With Mismatch-Repair Deficient and Epstein-Barr Virus Positive Gastric Cancer

Science.gov (United States)

2017-11-15

Epstein-Barr Virus Positive; Gastric Adenocarcinoma; Mismatch Repair Protein Deficiency; Stage IB Gastric Cancer AJCC v7; Stage II Gastric Cancer AJCC v7; Stage IIA Gastric Cancer AJCC v7; Stage IIB Gastric Cancer AJCC v7; Stage III Gastric Cancer AJCC v7; Stage IIIA Gastric Cancer AJCC v7; Stage IIIB Gastric Cancer AJCC v7; Stage IIIC Gastric Cancer AJCC v7

Epigenetic silencing of MLH1 in endometrial cancers is associated with larger tumor volume, increased rate of lymph node positivity and reduced recurrence-free survival.

Science.gov (United States)

Cosgrove, Casey M; Cohn, David E; Hampel, Heather; Frankel, Wendy L; Jones, Dan; McElroy, Joseph P; Suarez, Adrian A; Zhao, Weiqiang; Chen, Wei; Salani, Ritu; Copeland, Larry J; O'Malley, David M; Fowler, Jeffrey M; Yilmaz, Ahmet; Chassen, Alexis S; Pearlman, Rachel; Goodfellow, Paul J; Backes, Floor J

2017-09-01

To determine the relationship between mismatch repair (MMR) classification and clinicopathologic features including tumor volume, and explore outcomes by MMR class in a contemporary cohort. Single institution cohort evaluating MMR classification for endometrial cancers (EC). MMR immunohistochemistry (IHC)±microsatellite instability (MSI) testing and reflex MLH1 methylation testing was performed. Tumors with MMR abnormalities by IHC or MSI and MLH1 methylation were classified as epigenetic MMR deficiency while those without MLH1 methylation were classified as probable MMR mutations. Clinicopathologic characteristics were analyzed. 466 endometrial cancers were classified; 75% as MMR proficient, 20% epigenetic MMR defects, and 5% as probable MMR mutations. Epigenetic MMR defects were associated with advanced stage, higher grade, presence of lymphovascular space invasion, and older age. MMR class was significantly associated with tumor volume, an association not previously reported. The epigenetic MMR defect tumors median volume was 10,220mm 3 compared to 3321mm 3 and 2,846mm 3 , for MMR proficient and probable MMR mutations respectively (PMLH1 methylation analysis defines a subset of tumors that have worse prognostic features and reduced RFS. Copyright © 2017 Elsevier Inc. All rights reserved.

Evolution and Adaptation in Pseudomonas aeruginosa Biofilms Driven by Mismatch Repair System-Deficient Mutators

DEFF Research Database (Denmark)

Luján, Adela M.; Maciá, María D.; Yang, Liang

2011-01-01

, which are rarely eradicated despite intensive antibiotic therapy. Current knowledge indicates that three major adaptive strategies, biofilm development, phenotypic diversification, and mutator phenotypes [driven by a defective mismatch repair system (MRS)], play important roles in P. aeruginosa chronic...... infections, but the relationship between these strategies is still poorly understood. We have used the flow-cell biofilm model system to investigate the impact of the mutS associated mutator phenotype on development, dynamics, diversification and adaptation of P. aeruginosa biofilms. Through competition...... diversification, evidenced by biofilm architecture features and by a wider range and proportion of morphotypic colony variants, respectively. Additionally, morphotypic variants generated in mutator biofilms showed increased competitiveness, providing further evidence for mutator-driven adaptive evolution...

A putative Lynch syndrome family carrying MSH2 and MSH6 variants of uncertain significance-functional analysis reveals the pathogenic one

DEFF Research Database (Denmark)

Kantelinen, Jukka; Hansen, Thomas V O; Kansikas, Minttu

2011-01-01

Inherited pathogenic mutations in the mismatch repair (MMR) genes, MSH2, MLH1, MSH6, and PMS2 predispose to Lynch syndrome (LS). However, the finding of a variant or variants of uncertain significance (VUS) in affected family members complicates the risk assessment. Here, we describe a putative LS...

Lynch syndrome-associated extracolonic tumors are rare in two extended families with the same EPCAM deletion

NARCIS (Netherlands)

Lynch, H.T.; Riegert-Johnson, D.L.; Snyder, C.; Lynch, J.F.; Hagenkord, J.; Boland, C.R.; Rhees, J.; Thibodeau, S.N.; Boardman, L.A.; Davies, J.; Kuiper, R.P.; Hoogerbrugge, N.; Ligtenberg, M.J.L.

2011-01-01

OBJECTIVES: The Lynch syndrome (LS) is an inherited cancer syndrome showing a preponderance of colorectal cancer (CRC) in context with endometrial cancer and several other extracolonic cancers, which is due to pathogenic mutations in the mismatch repair (MMR) genes, MLH1, MSH2, MSH6, and PMS2. Some

Lynch Syndrome Caused by Germline PMS2 Mutations: Delineating the Cancer Risk

NARCIS (Netherlands)

ten Broeke, Sanne W.; Brohet, Richard M.; Tops, Carli M.; van der Klift, Heleen M.; Velthuizen, Mary E.; Bernstein, Inge; Capellá Munar, Gabriel; Gomez Garcia, Encarna; Hoogerbrugge, Nicoline; Letteboer, Tom G. W.; Menko, Fred H.; Lindblom, Annika; Mensenkamp, Arjen R.; Moller, Pal; van Os, Theo A.; Rahner, Nils; Redeker, Bert J. W.; Sijmons, Rolf H.; Spruijt, Liesbeth; Suerink, Manon; Vos, Yvonne J.; Wagner, Anja; Hes, Frederik J.; Vasen, Hans F.; Nielsen, Maartje; Wijnen, Juul T.

2015-01-01

Purpose The clinical consequences of PMS2 germline mutations are poorly understood compared with other Lynch-associated mismatch repair gene (MMR) mutations. The aim of this European cohort study was to define the cancer risk faced by PMS2 mutation carriers. Methods Data were collected from 98 PMS2

Lynch Syndrome Caused by Germline PMS2 Mutations : Delineating the Cancer Risk

NARCIS (Netherlands)

ten Broeke, Sanne W.; Brohet, Richard M.; Tops, Carli M.; van der Klift, Heleen M.; Velthuizen, Mary E.; Bernstein, Inge; Capella Munar, Gabriel; Garcia, Encarna Gomez; Hoogerbrugge, Nicoline; Letteboer, Tom G. W.; Menko, Fred H.; Lindblom, Annika; Mensenkamp, Arjen R.; Moller, Pal; Van Os, Theo A.; Rahner, Nils; Redeker, Bert J. W.; Sijmons, Rolf H.; Spruijt, Liesbeth; Suerink, Manon; Vos, Yvonne J.; Wagner, Anja; Hes, Frederik J.; Vasen, Hans F.; Nielsen, Maartje; Wijnen, Juul T.

2015-01-01

Purpose The clinical consequences of PMS2 germline mutations are poorly understood compared with other Lynch-associated mismatch repair gene (MMR) mutations. The aim of this European cohort study was to define the cancer risk faced by PMS2 mutation carriers. Methods Data were collected from 98 PMS2

DNA demethylation by 5-aza-2-deoxycytidine treatment abrogates 17 beta-estradiol-induced cell growth and restores expression of DNA repair genes in human breast cancer cells.

Science.gov (United States)

Singh, Kamaleshwar P; Treas, Justin; Tyagi, Tulika; Gao, Weimin

2012-03-01

Prolonged exposure to elevated levels of estrogen is a risk factor for breast cancer. Though increased cell growth and loss of DNA repair capacity is one of the proposed mechanisms for estrogen-induced cancers, the mechanism through which estrogen induces cell growth and decreases DNA repair capacity is not clear. DNA hypermethylation is known to inactivate DNA repair genes and apoptotic response in cancer cells. Therefore, the objective of this study was to determine the role of DNA hypermethylation in estrogen-induced cell growth and regulation of DNA repair genes expression in breast cancer cells. To achieve this objective, the estrogen-responsive MCF-7 cells either pretreated with 5-aza-2-deoxycytidine (5-aza-dC) or untreated (as control) were exposed to 17 beta-estradiol (E2), and its effect on cell growth and expression of DNA repair genes were measured. The result revealed that 5-aza-dC abrogates the E2-induced growth in MCF-7 cells. An increased expression of OGG1, MSH4, and MLH1 by 5-aza-dC treatment alone, suggest the DNA hypermethylation as a potential cause for decreased expression of these genes in MCF-7 cells. The decreased expression of ERCC1, XPC, OGG1, and MLH1 by E2 alone and its restoration by co-treatment with 5-aza-dC further suggest that E2 reduces the expression of these DNA repair genes potentially through promoter hypermethylation. Reactivation of mismatch repair (MMR) gene MLH1 and abrogation of E2-induced cell growth by 5-aza-dC treatment suggest that estrogen causes increased growth in breast cancer cells potentially through the inhibition of MMR-mediated apoptotic response. In summary, this study suggests that estrogen increases cell growth and decreases the DNA repair capacity in breast cancer cells, at least in part, through epigenetic mechanism. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

PMS2 gene mutation results in DNA mismatch repair system failure in a case of adult granulosa cell tumor

OpenAIRE

Wang, Wen-Chung; Lee, Ya-Ting; Lai, Yen-Chein

2017-01-01

Background Granulosa cell tumors are rare ovarian malignancies. Their characteristics include unpredictable indolent growth with malignant potential and late recurrence. Approximately 95% are of adult type. Recent molecular studies have characterized the FOXL2 402C?>?G mutation in adult granulosa cell tumor. Our previous case report showed that unique FOXL2 402C?>?G mutation and defective DNA mismatch repair system are associated with the development of adult granulosa cell tumor. Findings In...

Immunohistochemical and DNA sequencing analysis on human mismatch repair gene MLH1 in cervical squamous cell carcinoma with LOH of this gene

NARCIS (Netherlands)

Hu, X.; Guo, Z.; Pang, T.; Li, Q.; Afink, G.; Pontén, J.

2000-01-01

BACKGROUND: The human MLH1 gene (hMLH1) is one of the DNA mismatch repair genes. Defects in these genes are believed to be the underlying cause of microsatellite instability (MSI). MSI has been demonstrated in many human cancers such as colon cancer and some female-specific tumors. The hMLH1 gene

RRAF-V600E is not involved in the colorectal tumorigenesis of HNPCC in patients with functional MLH1 and MSH2 genes

NARCIS (Netherlands)

Domingo, E; Niessen, RC; Oliveira, C; Alhopuro, P; Moutinho, C; Espin, E; Armengol, M; Sijmons, RH; Kleibeuker, JH; Seruca, R; Aaltonen, LA; Imai, K; Yamamoto, H; Schwartz, S; Hofstra, RMW

2005-01-01

Recently, it was shown that the oncogenic activation of BRAF, a member of the RAS/RAF family of kinases, by the V600E mutation is characteristic for sporadic colon tumors with microsatellite instability. Further, it was shown to associate with the silencing of the mismatch repair (MMR) gene MLH1 by

Down-regulation of DNA mismatch repair proteins in human and murine tumor spheroids: implications for multicellular resistance to alkylating agents.

Science.gov (United States)

Francia, Giulio; Green, Shane K; Bocci, Guido; Man, Shan; Emmenegger, Urban; Ebos, John M L; Weinerman, Adina; Shaked, Yuval; Kerbel, Robert S

2005-10-01

Similar to other anticancer agents, intrinsic or acquired resistance to DNA-damaging chemotherapeutics is a major obstacle for cancer therapy. Current strategies aimed at overcoming this problem are mostly based on the premise that tumor cells acquire heritable genetic mutations that contribute to drug resistance. Here, we present evidence for an epigenetic, tumor cell adhesion-mediated, and reversible form of drug resistance that is associated with a reduction of DNA mismatch repair proteins PMS2 and/or MLH1 as well as other members of this DNA repair process. Growth of human breast cancer, human melanoma, and murine EMT-6 breast cancer cell lines as multicellular spheroids in vitro, which is associated with increased resistance to many chemotherapeutic drugs, including alkylating agents, is shown to lead to a reproducible down-regulation of PMS2, MLH1, or, in some cases, both as well as MHS6, MSH3, and MSH2. The observed down-regulation is in part reversible by treatment of tumor spheroids with the DNA-demethylating agent, 5-azacytidine. Thus, treatment of EMT-6 mouse mammary carcinoma spheroids with 5-azacytidine resulted in reduced and/or disrupted cell-cell adhesion, which in turn sensitized tumor spheroids to cisplatin-mediated killing in vitro. Our results suggest that antiadhesive agents might sensitize tumor spheroids to alkylating agents in part by reversing or preventing reduced DNA mismatch repair activity and that the chemosensitization properties of 5-azacytidine may conceivably reflect its role as a potential antiadhesive agent as well as reversal agent for MLH1 gene silencing in human tumors.

MMR vaccination of children with egg allergy is safe

DEFF Research Database (Denmark)

Andersen, Dorthe Vestergård; Jørgensen, Inger Merete

2013-01-01

Measles, mumps and rubella (MMR) vaccination is part of the Danish Childhood Vaccination Programme. It is known that children may react with anaphylaxis to MMR vaccines containing traces of egg protein. In Denmark, national clinical guidelines recommend that children with egg allergy be referred...... to vaccination at a paediatric ward despite changed recommendations in other countries. The purpose of this study was to determine whether children with egg allergy presented with anaphylactic/allergic reactions to MMR vaccination and to discuss whether Danish recommendations should be upheld....

A putative Lynch syndrome family carrying MSH2 and MSH6 variants of uncertain significance-functional analysis reveals the pathogenic one

DEFF Research Database (Denmark)

Kantelinen, Jukka; Hansen, Thomas V O; Kansikas, Minttu

2011-01-01

Inherited pathogenic mutations in the mismatch repair (MMR) genes, MSH2, MLH1, MSH6, and PMS2 predispose to Lynch syndrome (LS). However, the finding of a variant or variants of uncertain significance (VUS) in affected family members complicates the risk assessment. Here, we describe a putative LS...... and the tumor pathological data suggested that the missense variation in MSH2, the more common susceptibility gene in LS, would be the predisposing alteration. However, MSH2 VUS was surprisingly found to be MMR proficient in an in vitro MMR assay and a tolerant alteration in silico. By supplying evidence...... identified VUS before predictive gene testing and genetic counseling are offered to a family....

Programmed Death Ligand 1 Expression Among 700 Consecutive Endometrial Cancers: Strong Association With Mismatch Repair Protein Deficiency.

Science.gov (United States)

Li, Zaibo; Joehlin-Price, Amy S; Rhoades, Jennifer; Ayoola-Adeola, Martins; Miller, Karin; Parwani, Anil V; Backes, Floor J; Felix, Ashley S; Suarez, Adrian A

2018-01-01

This study aims to determine the prevalence of programmed death ligand 1 (PD-L1) expression in endometrial carcinoma (EC) and determine clinical and pathological associations. Immunohistochemistry for PD-L1 was performed on sections of a triple-core tissue microarray of 700 ECs. Positive PD-L1 expression, defined as 1% of cells staining positive, was evaluated in tumor and stromal compartments. Using age-adjusted logistic regression, we estimated odds ratios and 95% confidence intervals for associations between PD-L1 expression (overall and by staining compartment) with clinical and tumor characteristics. Kaplan-Meier plots and log-rank tests were used to evaluate associations between PD-L1 expression and EC-specific survival. PD-L1 expression was observed in 100 cases (14.3%), including 27 (3.9%) with expression in tumor cells only, 35 (5.0%) with expression in both tumor cells and stroma, and 38 (5.4%) with expression in stroma only. Expression was observed in ECs of different histologic types. Tumors characterized by loss of mismatch repair proteins were significantly associated with tumoral PD-L1 expression (P < 0.0001), but not with stromal PD-L1 expression. Both tumoral and stromal PD-L1 expressions were associated with high-grade endometrioid histology, nonendometrioid histology, and lymphovascular space invasion. We observed no significant associations between PD-L1 expression and EC-specific survival. PD-L1 is expressed in a significant proportion of EC and is associated with mismatch repair deficiency, potentially representing a mechanism of tumor immune evasion and a therapeutic target in EC.

Metachronous T-Lymphoblastic Lymphoma and Burkitt Lymphoma in a Child With Constitutional Mismatch Repair Deficiency Syndrome.

Science.gov (United States)

Alexander, Thomas B; McGee, Rose B; Kaye, Erica C; McCarville, Mary Beth; Choi, John K; Cavender, Cary P; Nichols, Kim E; Sandlund, John T

2016-08-01

Constitutional mismatch repair deficiency (CMMRD) is a cancer predisposition syndrome associated with a high risk of developing early-onset malignancies of the blood, brain, and intestinal tract. We present the case of a patient with T-lymphoblastic lymphoma at the age of 3 years, followed by Burkitt lymphoma 10 years later. This patient also exhibited numerous nonmalignant findings including café au lait spots, lipomas, bilateral renal nodules, a nonossifying fibroma, multiple colonic adenomas, and a rapidly enlarging pilomatrixoma. The spectrum of malignant and nonmalignant neoplasms in this patient highlights the remarkable diversity, and early onset, of lesions seen in children with CMMRD. © 2016 Wiley Periodicals, Inc.

Single nucleotide polymorphisms of DNA mismatch repair genes MSH2 and MLH1 confer susceptibility to esophageal cancer.

Science.gov (United States)

Sun, Ming-Zhong; Ju, Hui-Xiang; Zhou, Zhong-Wei; Jin, Hao; Zhu, Rong

2014-01-01

Defects in DNA mismatch repair genes like MSH2 and MLH1 confer increased risk of cancers. Here, single nucleotide polymorphisms (SNPs) in MSH2 and MLH1 were investigated for their potential contribution to the risk of esophageal cancer. This study recruited 614 participants from Affiliated Yancheng Hospital, School of Medicine, Southeast University, of which 289 were patients with esophageal cancer, and the remainder was healthy individuals who served as a control group. Two SNPs, MSH2 c.2063T>G and MLH1 IVS14-19A>G, were genotyped using PCR-RFLP. Statistical analysis was performed using chi-square test and logistic regression analysis. Carriers of the MSH2 c.2063G allele were at significantly higher risk for esophageal cancer compared to individuals with the TT genotype [OR = 3.36, 95% confidence interval (CI): 1.18-11.03]. The MLH1 IVS14-19A>G allele also conferred significantly increased (1.70-fold) for esophageal cancer compared to the AA genotype (OR = 1.70, 95% CI: 1.13-5.06). Further, the variant alleles interacted such that individuals with the susceptible genotypes at both MSH2 and MLH1 had a significantly exacerbated risk for esophageal cancer (OR = 12.38, 95% CI: 3.09-63.11). In brief, SNPs in the DNA mismatch repair genes MSH2 and MLH1 increase the risk of esophageal cancer. Molecular investigations are needed to uncover the mechanism behind their interaction effect.

Tissue expression of MLH1, PMS2, MSH2, and MSH6 proteins and prognostic value of microsatellite instability in Wilms tumor: experience of 45 cases.

Science.gov (United States)

Diniz, Gulden; Aktas, Safiye; Cubuk, Cankut; Ortac, Ragip; Vergin, Canan; Olgun, Nur

2013-05-01

Although the importance of microsatellite instability (MSI) and mismatch repair genes (MMR) is strongly established in colorectal cancer seen in the Lynch syndrome, its significance has not been fully established in Wilms tumor (WT). The aim of this study was to determine the prognostic value of MSI and MMR proteins in WT. This study included 45 pediatric cases with nephroblastoma. Protein expression was analyzed by immunohistochemistry of archival tissue sections. Real-time PCR melting analysis and fluorescence capillary electrophoresis (FCE) were performed to evaluate the MSI markers BAT25, BAT26, NR21, NR24, MONO27, penta D, and penta C in DNA extracted from tumor and normal tissues. Lower levels of MSI were observed in six cases (13.3%). There were no statistically significant correlations between MSI and some clinical prognostic factors such as stage of the tumors, and survival rates. Nineteen tumors (42.2%) showed loss of protein expression of MLH1, PMS2, MSH2, or MSH6. MMR protein defects were correlated with size (P = .021), and stage (P = .019) of the tumor, and survival rates (P < .01).Similarly MSI was also correlated with the size of the tumor (P = .046). This study showed that a small proportion of WT might be associated with the presence of MSI, as is the case with defects of DNA mismatch repair genes in the pathogenesis of WT. However, there was no concordance with the frequency of tissue expression of MMR proteins and MSI. These findings suggest that MMR genes may play an important role in the development of WT via different pathways.

Guidelines for surveillance of individuals with constitutional mismatch repair-deficiency proposed by the European Consortium "Care for CMMR-D" (C4CMMR-D).

Science.gov (United States)

Vasen, H F A; Ghorbanoghli, Z; Bourdeaut, F; Cabaret, O; Caron, O; Duval, A; Entz-Werle, N; Goldberg, Y; Ilencikova, D; Kratz, C P; Lavoine, N; Loeffen, J; Menko, F H; Muleris, M; Sebille, G; Colas, C; Burkhardt, B; Brugieres, L; Wimmer, K

2014-05-01

Lynch syndrome (LS) is an autosomal dominant disorder caused by a defect in one of the DNA mismatch repair genes: MLH1, MSH2, MSH6 and PMS2. In the last 15 years, an increasing number of patients have been described with biallelic mismatch repair gene mutations causing a syndrome referred to as 'constitutional mismatch repair-deficiency' (CMMR-D). The spectrum of cancers observed in this syndrome differs from that found in LS, as about half develop brain tumours, around half develop digestive tract cancers and a third develop haematological malignancies. Brain tumours and haematological malignancies are mainly diagnosed in the first decade of life, and colorectal cancer (CRC) and small bowel cancer in the second and third decades of life. Surveillance for CRC in patients with LS is very effective. Therefore, an important question is whether surveillance for the most common CMMR-D-associated cancers will also be effective. Recently, a new European consortium was established with the aim of improving care for patients with CMMR-D. At a workshop of this group held in Paris in June 2013, one of the issues addressed was the development of surveillance guidelines. In 1968, criteria were proposed by WHO that should be met prior to the implementation of screening programmes. These criteria were used to assess surveillance in CMMR-D. The evaluation showed that surveillance for CRC is the only part of the programme that largely complies with the WHO criteria. The values of all other suggested screening protocols are unknown. In particular, it is questionable whether surveillance for haematological malignancies improves the already favourable outcome for patients with these tumours. Based on the available knowledge and the discussions at the workshop, the European consortium proposed a surveillance protocol. Prospective collection of all results of the surveillance is needed to evaluate the effectiveness of the programme.

Mismatch repair defective breast cancer in the hereditary nonpolyposis colorectal cancer syndrome

DEFF Research Database (Denmark)

Jensen, Uffe Birk; Sunde, Lone; Timshel, Susanne

2010-01-01

of MLH1, MSH2 or MSH6 corresponding to the mutations identified in 7 of the 16 cases investigated, and these tumors were diagnosed at mean 50 (33-66) years of age. The demonstration of defective MMR in a substantial proportion of the breast cancers studied links yet another tumor type to HNPCC. Though...

An Unusual Case of Constitutional Mismatch Repair Deficiency Syndrome With Anaplastic Ganglioglioma, Colonic Adenocarcinoma, Osteosarcoma, Acute Myeloid Leukemia, and Signs of Neurofibromatosis Type 1: Case Report.

Science.gov (United States)

Daou, Badih; Zanello, Marc; Varlet, Pascale; Brugieres, Laurence; Jabbour, Pascal; Caron, Olivier; Lavoine, Noémie; Dhermain, Frederic; Willekens, Christophe; Beuvon, Frederic; Malka, David; Lechapt-Zalcmann, Emmanuèle; Abi Lahoud, Georges

2015-07-01

Constitutional mismatch repair deficiency (CMMRD) syndrome is a disorder with recessive inheritance caused by biallelic mismatch repair gene mutations, in which mismatch repair defects are inherited from both parents. This syndrome is associated with multiple cancers occurring in childhood. The most common tumors observed with CMMRD include brain tumors, digestive tract tumors, and hematological malignancies. The aim of this study was to report new phenotypic expressions of CMMRD syndrome and add new insight to the existing knowledge about this disease. A review of the literature was conducted and recommendation for surveillance and follow-up in patients with CMMRD are proposed. We report for the first time in the literature, the case of a 22-year-old female patient who was diagnosed with CMMRD syndrome, with the development of 2 unusual tumors: an anaplastic ganglioglioma and an osteosarcoma. She presented initially with an anaplastic ganglioglioma and later developed several malignancies including colonic adenocarcinoma, osteosarcoma, and acute myeloid leukemia. The patient had an atypical course of her disease with development of the initial malignancy at an older age and a remarkably long survival period despite developing aggressive tumors. Many aspects of this disease are still unknown. We identified a case of CMMRD in a patient presenting with an anaplastic ganglioglioma, who underwent successful surgical resection, chemotherapy, and radiotherapy and has had one of the longest survival periods known with this disease. This case broadens the tumor spectrum observed with CMMRD syndrome with anaplastic ganglioglioma and osteosarcoma as new phenotypic expressions of this genetic defect.

Lynch syndrome and Lynch syndrome mimics: The growing complex landscape of hereditary colon cancer

Science.gov (United States)

Carethers, John M; Stoffel, Elena M

2015-01-01

Hereditary non-polyposis colorectal cancer (HNPCC) was previously synonymous with Lynch syndrome; however, identification of the role of germline mutations in the DNA mismatch repair (MMR) genes has made it possible to differentiate Lynch syndrome from other conditions associated with familial colorectal cancer (CRC). Broadly, HNPCC may be dichotomized into conditions that demonstrate defective DNA MMR and microsatellite instability (MSI) vs those conditions that demonstrate intact DNA MMR. Conditions characterized by MMR deficient CRCs include Lynch syndrome (germline MMR mutation), Lynch-like syndrome (biallelic somatic MMR mutations), constitutional MMR deficiency syndrome (biallelic germline MMR mutations), and sporadic MSI CRC (somatic biallelic methylation of MLH1). HNPCC conditions with intact DNA MMR associated with familial CRC include polymerase proofreading associated polyposis and familial colorectal cancer type X. Although next generation sequencing technologies have elucidated the genetic cause for some HNPCC conditions, others remain genetically undefined. Differentiating between Lynch syndrome and the other HNPCC disorders has profound implications for cancer risk assessment and surveillance of affected patients and their at-risk relatives. Clinical suspicion coupled with molecular tumor analysis and testing for germline mutations can help differentiate the clinical mimicry within HNPCC and facilitate diagnosis and management. PMID:26309352

Lynch syndrome and Lynch syndrome mimics: The growing complex landscape of hereditary colon cancer.

Science.gov (United States)

Carethers, John M; Stoffel, Elena M

2015-08-21

Hereditary non-polyposis colorectal cancer (HNPCC) was previously synonymous with Lynch syndrome; however, identification of the role of germline mutations in the DNA mismatch repair (MMR) genes has made it possible to differentiate Lynch syndrome from other conditions associated with familial colorectal cancer (CRC). Broadly, HNPCC may be dichotomized into conditions that demonstrate defective DNA MMR and microsatellite instability (MSI) vs those conditions that demonstrate intact DNA MMR. Conditions characterized by MMR deficient CRCs include Lynch syndrome (germline MMR mutation), Lynch-like syndrome (biallelic somatic MMR mutations), constitutional MMR deficiency syndrome (biallelic germline MMR mutations), and sporadic MSI CRC (somatic biallelic methylation of MLH1). HNPCC conditions with intact DNA MMR associated with familial CRC include polymerase proofreading associated polyposis and familial colorectal cancer type X. Although next generation sequencing technologies have elucidated the genetic cause for some HNPCC conditions, others remain genetically undefined. Differentiating between Lynch syndrome and the other HNPCC disorders has profound implications for cancer risk assessment and surveillance of affected patients and their at-risk relatives. Clinical suspicion coupled with molecular tumor analysis and testing for germline mutations can help differentiate the clinical mimicry within HNPCC and facilitate diagnosis and management.

Randomised cluster trial to support informed parental decision-making for the MMR vaccine

Directory of Open Access Journals (Sweden)

Bekker Hilary

2011-06-01

Full Text Available Abstract Background In the UK public concern about the safety of the combined measles, mumps and rubella [MMR] vaccine continues to impact on MMR coverage. Whilst the sharp decline in uptake has begun to level out, first and second dose uptake rates remain short of that required for population immunity. Furthermore, international research consistently shows that some parents lack confidence in making a decision about MMR vaccination for their children. Together, this work suggests that effective interventions are required to support parents to make informed decisions about MMR. This trial assessed the impact of a parent-centred, multi-component intervention (balanced information, group discussion, coaching exercise on informed parental decision-making for MMR. Methods This was a two arm, cluster randomised trial. One hundred and forty two UK parents of children eligible for MMR vaccination were recruited from six primary healthcare centres and six childcare organisations. The intervention arm received an MMR information leaflet and participated in the intervention (parent meeting. The control arm received the leaflet only. The primary outcome was decisional conflict. Secondary outcomes were actual and intended MMR choice, knowledge, attitude, concern and necessity beliefs about MMR and anxiety. Results Decisional conflict decreased for both arms to a level where an 'effective' MMR decision could be made one-week (effect estimate = -0.54, p Conclusions Whilst both the leaflet and the parent meeting reduced parents' decisional conflict, the parent meeting appeared to enable parents to act upon their decision leading to vaccination uptake.

Nucleotide sequence of the hexA gene for DNA mismatch repair in Streptococcus pneumoniae and homology of hexA to mutS of Escherichia coli and Salmonella typhimurium

International Nuclear Information System (INIS)

Priebe, S.D.; Hadi, S.M.; Greenberg, B.; Lacks, S.A.

1988-01-01

The Hex system of heteroduplex DNA base mismatch repair operates in Streptococcus pneumoniae after transformation and replication to correct donor and nascent DNA strands, respectively. A functionally similar system, called Mut, operates in Escherichia coli and Salmonella typhimurium. The nucleotide sequence of a 3.8-kilobase segment from the S. pneumoniae chromosome that includes the 2.7-kilobase hexA gene was determined. Chromosomal DNA used as donor to measure Hex phenotype was irradiated with UV light. An open reading frame that could encode a 17-kilodalton polypeptide (OrfC) was located just upstream of the gene encoding a polypeptide of 95 kilodaltons corresponding to HexA. Shine-Dalgarno sequences and putative promoters were identified upstream of each protein start site. Insertion mutations showed that only HexA functioned in mismatch repair and that the promoter for hexA transcription was located within the OrfC-coding region. The HexA polypeptide contains a consensus sequence for ATP- or GTP-binding sites in proteins. Comparison of the entire HexA protein sequence to that of MutS of S. typhimurium, showed the proteins to be homologous, inasmuch as 36% of their amino acid residues were identical. This homology indicates that the Hex and Mut systems of mismatch repair evolved from an ancestor common to the gram-positive streptococci and the gram-negative enterobacteria. It is the first direct evidence linking the two systems

Functional characterization of MLH1 missense variants identified in Lynch Syndrome patients

DEFF Research Database (Denmark)

Andersen, Sofie Dabros; Liberti, Sascha Emilie; Lützen, Anne

2012-01-01

Germline mutations in the human DNA mismatch repair (MMR) genes MSH2 and MLH1 are associated with the inherited cancer disorder Lynch Syndrome (LS), also known as Hereditary Nonpolyposis Colorectal Cancer or HNPCC. A proportion of MSH2 and MLH1 mutations found in suspected LS patients give rise...... localization and protein-protein interaction with the dimer partner PMS2 and the MMR-associated exonuclease 1. We show that a significant proportion of examined variant proteins have functional defects in either subcellular localization or protein-protein interactions, which is suspected to lead to the cancer...

Dissociating Long and Short-term Memory in Three-Month-Old Infants Using the Mismatch Response to Voice Stimuli.

Science.gov (United States)

Zinke, Katharina; Thöne, Leonie; Bolinger, Elaina M; Born, Jan

2018-01-01

Auditory event-related potentials (ERPs) have been successfully used in adults as well as in newborns to discriminate recall of longer-term and shorter-term memories. Specifically the Mismatch Response (MMR) to deviant stimuli of an oddball paradigm is larger if the deviant stimuli are highly familiar (i.e., retrieved from long-term memory) than if they are unfamiliar, representing an immediate change to the standard stimuli kept in short-term memory. Here, we aimed to extend previous findings indicating a differential MMR to familiar and unfamiliar deviants in newborns (Beauchemin et al., 2011), to 3-month-old infants who are starting to interact more with their social surroundings supposedly based on forming more (social) long-term representations. Using a voice discrimination paradigm, each infant was repeatedly presented with the word "baby" (400 ms, interstimulus interval: 600 ms, 10 min overall duration) pronounced by three different female speakers. One voice that was unfamiliar to the infants served as the frequently presented "standard" stimulus, whereas another unfamiliar voice served as the "unfamiliar deviant" stimulus, and the voice of the infant's mother served as the "familiar deviant." Data collection was successful for 31 infants (mean age = 100 days). The MMR was determined by the difference between the ERP to standard stimuli and the ERP to the unfamiliar and familiar deviant, respectively. The MMR to the familiar deviant (mother's voice) was larger, i.e., more positive, than that to the unfamiliar deviant between 100 and 400 ms post-stimulus over the frontal and central cortex. However, a genuine MMR differentiating, as a positive deflection, between ERPs to familiar deviants and standard stimuli was only found in the 300-400 ms interval. On the other hand, a genuine MMR differentiating, as a negative deflection, between ERPs to unfamiliar deviants from ERPs to standard stimuli was revealed for the 200-300 ms post-stimulus interval. Overall

Conformations of MutS in DNA mismatch repair

NARCIS (Netherlands)

F.S. Groothuizen (Flora)

2015-01-01

markdownabstract__Abstract__ Prior to cell division, the DNA containing the genetic information of a cell has to be copied. During this process, errors are sometimes incorporated (so-called mismatches), which may cause genetic abnormalities in future cells. To prevent this, cells contain a DNA

The Effect of Basepair Mismatch on DNA Strand Displacement

OpenAIRE

Broadwater, D.?W.?Bo; Kim, Harold?D.

2016-01-01

DNA strand displacement is a key reaction in DNA homologous recombination and DNA mismatch repair and is also heavily utilized in DNA-based computation and locomotion. Despite its ubiquity in science and engineering, sequence-dependent effects of displacement kinetics have not been extensively characterized. Here, we measured toehold-mediated strand displacement kinetics using single-molecule fluorescence in the presence of a single base pair mismatch. The apparent displacement rate varied si...

Using a multi-feature paradigm to measure mismatch responses to minimal sound contrasts in children with cochlear implants and hearing aids.

Science.gov (United States)

Uhlén, Inger; Engström, Elisabet; Kallioinen, Petter; Nakeva von Mentzer, Cecilia; Lyxell, Björn; Sahlén, Birgitta; Lindgren, Magnus; Ors, Marianne

2017-10-01

Our aim was to explore whether a multi-feature paradigm (Optimum-1) for eliciting mismatch negativity (MMN) would objectively capture difficulties in perceiving small sound contrasts in children with hearing impairment (HI) listening through their hearing aids (HAs) and/or cochlear implants (CIs). Children aged 5-7 years with HAs, CIs and children with normal hearing (NH) were tested in a free-field setting using a multi-feature paradigm with deviations in pitch, intensity, gap, duration, and location. There were significant mismatch responses across all subjects that were positive (p-MMR) for the gap and pitch deviants (F(1,43) = 5.17, p = 0.028 and F(1,43) = 6.56, p = 0.014, respectively) and negative (MMN) for the duration deviant (F(1,43) = 4.74, p = 0.035). Only the intensity deviant showed a significant group interaction with MMN in the HA group and p-MMR in the CI group (F(2,43) = 3.40, p = 0.043). The p-MMR correlated negatively with age, with the strongest correlation in the NH subjects. In the CI group, the late discriminative negativity (LDN) was replaced by a late positivity with a significant group interaction for the location deviant. Children with severe HI can be assessed through their hearing device with a fast multi-feature paradigm. For further studies a multi-feature paradigm including more complex speech sounds may better capture variation in auditory processing in these children. © 2017 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Sebaceous neoplasms and the immunoprofile of mismatch-repair proteins as a screening target for syndromic cases

DEFF Research Database (Denmark)

Boennelycke, Marie; Thomsen, Birthe M; Holck, Susanne

2015-01-01

(SAs) and 6 sebaceous carcinomas (SCs) were accrued. The expression of MLH1, MSH2, MSH6, and PMS2 was recorded. MLH1-deficient cases were tested for p16 status. RESULTS: Eighteen (56%) of the 32 specimens with SA or SC displayed MMR-protein deficiency, comprising 17 (65.4%) SAs (MSH2/MSH6 loss in 12......, MLH1/PMS2 loss in 3, MSH6 loss only in 2 cases) and 1 (16.7%) SC (MLH1/PMS2 loss). All 4 MLH1 deficient cases were p16-positive. CONCLUSION: A substantial proportion of sebaceous neoplasms were MMR-protein deficient and thus likely MTS candidates. Given the low prevalence of sebaceous neoplasms...

MUTYH Associated Polyposis (MAP)

DEFF Research Database (Denmark)

Poulsen, Marie Louise Mølgaard; Bisgaard, M L

2008-01-01

Adenomatous Polyposis (FAP) and to a lesser extend Lynch Syndrome, which are caused by germline mutations in the APC and Mismatch Repair (MMR) genes, respectively.Here we review research findings regarding MUTYH interactions, genotypic and phenotypic characteristics of MAP, as well as surveillance......MUTYH Associated Polyposis (MAP), a Polyposis predisposition caused by biallelic mutations in the Base Excision Repair (BER) gene MUTYH, confers a marked risk of colorectal cancer (CRC). The MAP phenotype is difficult to distinguish from other hereditary CRC syndromes. Especially from Familial...

Constitutional mismatch repair-deficiency syndrome presenting as colonic adenomatous polyposis: clues from the skin.

Science.gov (United States)

Jasperson, K W; Samowitz, W S; Burt, R W

2011-10-01

Constitutional mismatch repair-deficiency (CMMR-D) syndrome is an autosomal recessive condition characterized by hematologic malignancies, brain tumors, Lynch syndrome-associated cancers and skin manifestations reminiscent of neurofibromatosis type 1 (NF1). In contrast to Lynch syndrome, CMMR-D syndrome is exceptionally rare, onset typically occurs in infancy or early childhood and, as described in this report, may also present with colonic polyposis suggestive of attenuated familial adenomatous polyposis (AFAP) or MUTYH associated polyposis (MAP). Here we describe two sisters with CMMR-D syndrome due to germline bi-allelic MSH6 mutations. Both sisters are without cancer, are older than typical for this condition, have NF1 associated features and a colonic phenotype suspicious for an attenuated polyposis syndrome. This report highlights the role of skin examinations in leading to an underlying genetic diagnosis in individuals with colonic adenomatous polyposis, but without mutations associated with AFAP or MAP. © 2010 John Wiley & Sons A/S.

Identification of Factors Interacting with hMSH2 and hMLH1 in the Fetal Liver and Investigations of how Mitochondrial Dysfunction Creates a Mutator Phenotype

DEFF Research Database (Denmark)

Rasmussen, Anne Karin

mutations. Mutations in MMR genes cause hereditary non-polyposis colon cancer. In an effort to identify unidentified genes involved in MMR and tissue-specific MMRassociated factors, we employed the yeast two-hybrid system, using the human hMSH2 as bait and a human fetal liver cDNA library as prey. We...... between mitochondrial activity and genomic instability. Mitochondrial dysfunction and genetic instability are characteristic features of cancer cells. Furthermore, mitochondrial dysfunction is a key feature of aging due to accumulation of mutations in mtDNA. Our studies in a yeast model system suggest......Increased spontaneous mutation frequency is associated with increased cancer risk. However, the relative contribution of spontaneous endogenous mutagenesis to carcinogenesis is not known today. Defects in the postreplication DNA mismatch repair (MMR) pathway are recognized to increase spontaneous...

An effect from anticipation also in hereditary nonpolyposis colorectal cancer families without identified mutations

DEFF Research Database (Denmark)

Timshel, Susanne; Therkildsen, Christina; Bendahl, Pär-Ola

2009-01-01

Optimal prevention of hereditary cancer is central and requires initiation of surveillance programmes and/or prophylactic measures at a safe age. Anticipation, expressed as an earlier age at onset in successive generations, has been demonstrated in hereditary nonpolyposis colorectal cancer (HNPCC......). We specifically addressed anticipation in phenotypic HNPCC families without disease-predisposing mismatch repair (MMR) defects since risk estimates and age at onset are particularly difficult to determine in this cohort. The national Danish HNPCC register was used to identify families who fulfilled...... the Amsterdam criteria for HNPCC and showed normal MMR function and/or lack of disease-predisposing MMR gene mutation. In total, 319 cancers from 212 parent-child pairs in 99 families were identified. A paired t-test and a bivariate statistical model were used to assess anticipation. Both methods demonstrated...

Role for Genetic Anticipation in Lynch Syndrome

DEFF Research Database (Denmark)

Nilbert, Mef; Timshel, Susanne; Bernstein, Inge

2009-01-01

PURPOSE: Anticipation (ie, an earlier age at onset in successive generations) is linked to repeat expansion in neurodegenerative syndromes, whereas its role in hereditary cancer is unclear. We assessed anticipation in Lynch syndrome (hereditary nonpolyposis colorectal cancer [HNPCC]), in which DNA...... mismatch repair (MMR) defects cause early and accelerated tumor development with a broad tumor spectrum. PATIENTS AND METHODS: In the population-based Danish HNPCC registry, 407 MMR gene mutation carriers who had developed cancer associated with Lynch syndrome, were identified. These individuals formed 290....... The effect remained when cancers diagnosed at surveillance were excluded, applied to maternal as well as paternal inheritance, and was independent of the MMR gene mutated. CONCLUSION: The effect from anticipation demonstrated in this large, population-based Lynch syndrome cohort underscores the need...

Strategy for Imidazotetrazine Prodrugs with Anticancer Activity Independent of MGMT and MMR

Science.gov (United States)

2012-01-01

The imidazotetrazine ring is an acid-stable precursor and prodrug of highly reactive alkyl diazonium ions. We have shown that this reactivity can be managed productively in an aqueous system for the generation of aziridinium ions with 96% efficiency. The new compounds are potent DNA alkylators and have antitumor activity independent of the O6-methylguanine-DNA methyltransferase and DNA mismatch repair constraints that limit the use of Temozolomide. PMID:24900418

High frequency induction of mitotic recombination by ionizing radiation in Mlh1 null mouse cells

International Nuclear Information System (INIS)

Wang Qi; Ponomareva, Olga N.; Lasarev, Michael; Turker, Mitchell S.

2006-01-01

Mitotic recombination in somatic cells involves crossover events between homologous autosomal chromosomes. This process can convert a cell with a heterozygous deficiency to one with a homozygous deficiency if a mutant allele is present on one of the two homologous autosomes. Thus mitotic recombination often represents the second mutational step in tumor suppressor gene inactivation. In this study we examined the frequency and spectrum of ionizing radiation (IR)-induced autosomal mutations affecting Aprt expression in a mouse kidney cell line null for the Mlh1 mismatch repair (MMR) gene. The mutant frequency results demonstrated high frequency induction of mutations by IR exposure and the spectral analysis revealed that most of this response was due to the induction of mitotic recombinational events. High frequency induction of mitotic recombination was not observed in a DNA repair-proficient cell line or in a cell line with an MMR-independent mutator phenotype. These results demonstrate that IR exposure can initiate a process leading to mitotic recombinational events and that MMR function suppresses these events from occurring

PMS2 expression in epithelial ovarian cancer is posttranslationally regulated by Akt and essential for platinum-induced apoptosis.

Science.gov (United States)

Jia, Jinghui; Wang, Zehua; Cai, Jing; Zhang, Yuan

2016-03-01

Epithelial ovarian cancer (EOC) is the most lethal of the gynecologic malignancies, mainly due to the advanced stage at diagnosis and development of cisplatin resistance. The sensitivity of tumor cells to cisplatin is frequently affected by defect in DNA mismatch repair (MMR), which repairs mispaired DNA sequences and regulates DNA-damage-induced apoptosis. However, the role of postmeiotic segregation increased 2 (PMS2), a member of MMR protein family, in cisplatin resistance remains elusive. In the present study, we demonstrated the frequent deficiency of PMS2 and phosphorylation of Akt in EOC cell lines and tissues. Results of complex immunoprecipitation (co-IP) and protein stability assay indicated that activated Akt could directly bind to PMS2 and cause degradation of PMS2 in EOC cells. In addition, functional experiments revealed that PMS2 was required for cisplatin-induced apoptosis and cell cycle arrest in G2/M phase. These findings provide a novel insight into molecular mechanisms linking MMR with chemoresistance and suggest that stabilization of PMS2 expression may be useful in overcoming the cisplatin resistance in EOC.

Comprehensive Mutation Analysis of PMS2 in a Large Cohort of Probands Suspected of Lynch Syndrome or Constitutional Mismatch Repair Deficiency Syndrome.

Science.gov (United States)

van der Klift, Heleen M; Mensenkamp, Arjen R; Drost, Mark; Bik, Elsa C; Vos, Yvonne J; Gille, Hans J J P; Redeker, Bert E J W; Tiersma, Yvonne; Zonneveld, José B M; García, Encarna Gómez; Letteboer, Tom G W; Olderode-Berends, Maran J W; van Hest, Liselotte P; van Os, Theo A; Verhoef, Senno; Wagner, Anja; van Asperen, Christi J; Ten Broeke, Sanne W; Hes, Frederik J; de Wind, Niels; Nielsen, Maartje; Devilee, Peter; Ligtenberg, Marjolijn J L; Wijnen, Juul T; Tops, Carli M J

2016-11-01

Monoallelic PMS2 germline mutations cause 5%-15% of Lynch syndrome, a midlife cancer predisposition, whereas biallelic PMS2 mutations cause approximately 60% of constitutional mismatch repair deficiency (CMMRD), a rare childhood cancer syndrome. Recently improved DNA- and RNA-based strategies are applied to overcome problematic PMS2 mutation analysis due to the presence of pseudogenes and frequent gene conversion events. Here, we determined PMS2 mutation detection yield and mutation spectrum in a nationwide cohort of 396 probands. Furthermore, we studied concordance between tumor IHC/MSI (immunohistochemistry/microsatellite instability) profile and mutation carrier state. Overall, we found 52 different pathogenic PMS2 variants explaining 121 Lynch syndrome and nine CMMRD patients. In vitro mismatch repair assays suggested pathogenicity for three missense variants. Ninety-one PMS2 mutation carriers (70%) showed isolated loss of PMS2 in their tumors, for 31 (24%) no or inconclusive IHC was available, and eight carriers (6%) showed discordant IHC (presence of PMS2 or loss of both MLH1 and PMS2). Ten cases with isolated PMS2 loss (10%; 10/97) harbored MLH1 mutations. We confirmed that recently improved mutation analysis provides a high yield of PMS2 mutations in patients with isolated loss of PMS2 expression. Application of universal tumor prescreening methods will however miss some PMS2 germline mutation carriers. © 2016 WILEY PERIODICALS, INC.

MMR vaccine in 14 months old children, intramuscular versus subcutaneous administration

NARCIS (Netherlands)

Lafeber AF; Klis FRM van der; Marzec AHJO; Labadie J; Ommen R van; Strieder TG; Berbers GAM; Utrecht Stichting Thuiszorg; Amersfoort Stichting Thuiszorg Eemland (STE),; LVO

2001-01-01

In this study we compared the recommended subcutaneous administration of the RIVM MMR vaccine with the intramuscular administration for both safety and immunogenicity. Study subjects were 14 months old children, living in Amersfoort or Utrecht, who were eligible for their first MMR vaccination.

Dissociating Long and Short-term Memory in Three-Month-Old Infants Using the Mismatch Response to Voice Stimuli

Directory of Open Access Journals (Sweden)

Katharina Zinke

2018-01-01

Full Text Available Auditory event-related potentials (ERPs have been successfully used in adults as well as in newborns to discriminate recall of longer-term and shorter-term memories. Specifically the Mismatch Response (MMR to deviant stimuli of an oddball paradigm is larger if the deviant stimuli are highly familiar (i.e., retrieved from long-term memory than if they are unfamiliar, representing an immediate change to the standard stimuli kept in short-term memory. Here, we aimed to extend previous findings indicating a differential MMR to familiar and unfamiliar deviants in newborns (Beauchemin et al., 2011, to 3-month-old infants who are starting to interact more with their social surroundings supposedly based on forming more (social long-term representations. Using a voice discrimination paradigm, each infant was repeatedly presented with the word “baby” (400 ms, interstimulus interval: 600 ms, 10 min overall duration pronounced by three different female speakers. One voice that was unfamiliar to the infants served as the frequently presented “standard” stimulus, whereas another unfamiliar voice served as the “unfamiliar deviant” stimulus, and the voice of the infant’s mother served as the “familiar deviant.” Data collection was successful for 31 infants (mean age = 100 days. The MMR was determined by the difference between the ERP to standard stimuli and the ERP to the unfamiliar and familiar deviant, respectively. The MMR to the familiar deviant (mother’s voice was larger, i.e., more positive, than that to the unfamiliar deviant between 100 and 400 ms post-stimulus over the frontal and central cortex. However, a genuine MMR differentiating, as a positive deflection, between ERPs to familiar deviants and standard stimuli was only found in the 300–400 ms interval. On the other hand, a genuine MMR differentiating, as a negative deflection, between ERPs to unfamiliar deviants from ERPs to standard stimuli was revealed for the 200–300 ms

Reporting of MMR evidence in professional publications: 1988–2007

Science.gov (United States)

Hilton, S; Hunt, K; Langan, M; Hamilton, V; Petticrew, M

2009-01-01

Objective: To examine how journals and magazines disseminate research evidence and guidance on best practice to health professionals by aligning commentaries on measles, mumps, and rubella vaccine (MMR) evidence in journals with key events in the MMR controversy. Design: Content analysis. Data sources: Comment articles in six commonly read UK publications. Main outcome measures: Number of comment pieces by publication, year and article type; trends in the focus, tone and inclusion of recommendations on MMR. Results: 860 articles met the inclusion criteria (BMJ n = 104, Community Practitioner n = 45, Health Visitor n = 24, Practice Nurse n = 61, Nursing Standard n = 61 and Pulse n = 565). Of these 860 comment pieces, 264 made some reference to evidence endorsing the safety of MMR. Around one in 10 were rated as negative (10.9%, n = 29) or neutral (11.3%, n = 30) in relation to MMR safety, and nearly a quarter (22.7%, n = 60) were rated as mixed. Following the publication of Wakefield et al’s 1998 paper there was a period of neutrality. In 2000, despite growing public concerns and widespread media coverage, fewer than 20 comment pieces were published. Less than a quarter of comment pieces (n = 196, 22.7%) included recommendations. Conclusion: While a period of neutrality may reflect a professional response to uncertainty by holding back until consensus emerges, it may also represent a missed opportunity to promote evidence-based practice. PMID:19414434

Suspected Lynch syndrome associated MSH6 variants: A functional assay to determine their pathogenicity.

Directory of Open Access Journals (Sweden)

Hellen Houlleberghs

2017-05-01

Full Text Available Lynch syndrome (LS is a hereditary cancer predisposition caused by inactivating mutations in DNA mismatch repair (MMR genes. Mutations in the MSH6 DNA MMR gene account for approximately 18% of LS cases. Many LS-associated sequence variants are nonsense and frameshift mutations that clearly abrogate MMR activity. However, missense mutations whose functional implications are unclear are also frequently seen in suspected-LS patients. To conclusively diagnose LS and enroll patients in appropriate surveillance programs to reduce morbidity as well as mortality, the functional consequences of these variants of uncertain clinical significance (VUS must be defined. We present an oligonucleotide-directed mutagenesis screen for the identification of pathogenic MSH6 VUS. In the screen, the MSH6 variant of interest is introduced into mouse embryonic stem cells by site-directed mutagenesis. Subsequent selection for MMR-deficient cells using the DNA damaging agent 6-thioguanine (6TG allows the identification of MMR abrogating VUS because solely MMR-deficient cells survive 6TG exposure. We demonstrate the efficacy of the genetic screen, investigate the phenotype of 26 MSH6 VUS and compare our screening results to clinical data from suspected-LS patients carrying these variant alleles.

An Unusual Ligand Coordination Gives Rise to a New Family of Rhodium Metalloinsertors with Improved Selectivity and Potency

Science.gov (United States)

2015-01-01

Rhodium metalloinsertors are octahedral complexes that bind DNA mismatches with high affinity and specificity and exhibit unique cell-selective cytotoxicity, targeting mismatch repair (MMR)-deficient cells over MMR-proficient cells. Here we describe a new generation of metalloinsertors with enhanced biological potency and selectivity, in which the complexes show Rh–O coordination. In particular, it has been found that both Δ- and Λ-[Rh(chrysi)(phen)(DPE)]2+ (where chrysi =5,6 chrysenequinone diimmine, phen =1,10-phenanthroline, and DPE = 1,1-di(pyridine-2-yl)ethan-1-ol) bind to DNA containing a single CC mismatch with similar affinities and without racemization. This is in direct contrast with previous metalloinsertors and suggests a possible different binding disposition for these complexes in the mismatch site. We ascribe this difference to the higher pKa of the coordinated immine of the chrysi ligand in these complexes, so that the complexes must insert into the DNA helix with the inserting ligand in a buckled orientation; spectroscopic studies in the presence and absence of DNA along with the crystal structure of the complex without DNA support this assignment. Remarkably, all members of this new family of compounds have significantly increased potency in a range of cellular assays; indeed, all are more potent than cisplatin and N-methyl-N′-nitro-nitrosoguanidine (MNNG, a common DNA-alkylating chemotherapeutic agent). Moreover, the activities of the new metalloinsertors are coupled with high levels of selective cytotoxicity for MMR-deficient versus proficient colorectal cancer cells. PMID:25254630

Mutagenic effect of cadmium on tetranucleotide repeats in human cells

Energy Technology Data Exchange (ETDEWEB)

Slebos, Robbert J.C. [Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 (United States) and Department of Otolaryngology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 (United States)]. E-mail: r.slebos@vanderbilt.edu; Li Ming [Department of Biostatistics, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 (United States); Evjen, Amy N. [Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 (United States); Coffa, Jordy [Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 (United States); Shyr, Yu [Department of Biostatistics, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 (United States); Yarbrough, Wendell G. [Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 (United States); Department of Otolaryngology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232 (United States)

2006-12-01

Cadmium is a human carcinogen that affects cell proliferation, apoptosis and DNA repair processes that are all important to carcinogenesis. We previously demonstrated that cadmium inhibits DNA mismatch repair (MMR) in yeast cells and in human cell-free extracts (H.W. Jin, A.B. Clark, R.J.C. Slebos, H. Al-Refai, J.A. Taylor, T.A. Kunkel, M.A. Resnick, D.A. Gordenin, Cadmium is a mutagen that acts by inhibiting mismatch repair, Nat. Genet. 34 (3) (2003) 326-329), but cadmium also inhibits DNA excision repair. For this study, we selected a panel of three hypermutable tetranucleotide markers (MycL1, D7S1482 and DXS981) and studied their suitability as readout for the mutagenic effects of cadmium. We used a clonal derivative of the human fibrosarcoma cell line HT1080 to assess mutation levels in microsatellites after cadmium and/or N-methyl-N-nitro-N-nitrosoguanidine (MNNG) exposure to study effects of cadmium in the presence or absence of base damage. Mutations were measured in clonally expanded cells obtained by limiting dilution after exposure to zero dose, 0.5 {mu}M cadmium, 5 nM MNNG or a combination of 0.5 {mu}M cadmium and 5 nM MNNG. Exposure of HT1080-C1 to cadmium led to statistically significant increases in microsatellite mutations, either with or without concurrent exposure to MNNG. A majority of the observed mutant molecules involved 4-nucleotide shifts consistent with DNA slippage mutations that are normally repaired by MMR. These results provide evidence for the mutagenic effects of low, environmentally relevant levels of cadmium in intact human cells and suggest that inhibition of DNA repair is involved.

Identification of a novel PMS2 alteration c.505C>G (R169G) in trans with a PMS2 pathogenic mutation in a patient with constitutional mismatch repair deficiency.

Science.gov (United States)

Mork, Maureen E; Borras, Ester; Taggart, Melissa W; Cuddy, Amanda; Bannon, Sarah A; You, Y Nancy; Lynch, Patrick M; Ramirez, Pedro T; Rodriguez-Bigas, Miguel A; Vilar, Eduardo

2016-10-01

Constitutional mismatch repair deficiency syndrome (CMMRD) is a rare autosomal recessive predisposition to colorectal polyposis and other malignancies, often childhood-onset, that is caused by biallelic inheritance of mutations in the same mismatch repair gene. Here, we describe a patient with a clinical diagnosis of CMMRD based on colorectal polyposis and young-onset endometrial cancer who was identified to have two alterations in trans in PMS2: one known pathogenic mutation (c.1831insA; p.Ile611Asnfs*2) and one novel variant of uncertain significance (c.505C>G; p.Arg169Glu), a missense alteration. We describe the clinical and molecular features in the patient harboring this novel alteration c.505C>G, who meets clinical criteria for CMMRD and exhibits molecular evidence supporting a diagnosis of CMMRD. Although experimental validation is needed to confirm its pathogenicity, PMS2 c.505C>G likely has functional consequences that contributes to our patient's phenotype based on the patient's clinical presentation, tumor studies, and bioinformatics analysis.

Hsp27, Hsp70 and mismatch repair proteins hMLH1 and hMSH2 expression in peripheral blood lymphocytes from healthy subjects and cancer patients.

Science.gov (United States)

Nadin, Silvina Beatriz; Vargas-Roig, Laura M; Drago, Gisela; Ibarra, Jorge; Ciocca, Daniel R

2007-07-08

Mismatch repair (MMR) deficiency and higher expression levels of heat shock proteins (Hsps) have been implicated with drug resistance to topoisomerase II poisons (doxorubicin) and to platinum compounds (cisplatin). This study was designed to determine individual influences of doxorubicin and cisplatin treatment on the expression of Hsp27, Hsp70, hMLH1 and hMSH2 proteins and in the DNA damage status in peripheral blood lymphocytes (PBLs). In addition, we studied whether these proteins and the DNA damage correlated with the survival of cancer patients. PBLs from 10 healthy donors and 25 cancer patients (before and after three cycles of chemotherapy) were exposed to in vitro treatments: C (control), HS (heat shock at 42 degrees C), Do or Pt (doxorubicin or cisplatin alone), and HS+Do or HS+Pt (heat shock+doxorubicin or heat shock+cisplatin). PBLs were collected at time 0 (T0: immediately after drug treatment) and after 24h of repair (T24). Hsp27, Hsp70, hMLH1 and hMSH2 were studied by immunocytochemistry and the DNA damage by alkaline comet assay. Immunofluorescence studies and confocal microscopy revealed that hMLH1 and hMSH2 colocalized with Hsp27 and Hsp72 (inducible form of Hsp70). hMLH1 and hMSH2 were significantly induced by Pt and HS+Pt at T24 in cancer patients, but only modestly influenced by Do. Cancer patients presented higher basal expression of total and nuclear Hsp27 and Hsp70 than controls, and these proteins were also increased by HS, Do and HS+Do. The Hsp70 induction by Pt and HS+Pt was noted in cancer patients, especially nuclear Hsp70. In cancer patients, basal DNA damage was slightly higher than in healthy persons; and after Pt and HS+Pt treatments, DNA migration and number of apoptotic cells were higher than controls. Hsps accomplished a cytoprotective function in pre-chemotherapy PBLs (HS before Do or Pt), but not in post-chemotherapy samples. In Pt-treated patients the ratio N/C (nuclear/cytoplasmic) of Hsp27 was related to disease free survival

Complex pattern of immune evasion in MSI colorectal cancer.

Science.gov (United States)

Ozcan, Mine; Janikovits, Jonas; von Knebel Doeberitz, Magnus; Kloor, Matthias

2018-01-01

Mismatch repair (MMR)-deficient cancers accumulate multiple insertion/deletion mutations at coding microsatellites (cMS), which give rise to frameshift peptide neoantigens. The high mutational neoantigen load of MMR-deficient cancers is reflected by pronounced anti-tumoral immune responses of the host and high responsiveness towards immune checkpoint blockade. However, immune evasion mechanisms can interfere with the immune response against MMR-deficient tumors. We here performed a comprehensive analysis of immune evasion in MMR-deficient colorectal cancers, focusing on HLA class I-mediated antigen presentation. 72% of MMR-deficient colorectal cancers of the DFCI database harbored alterations affecting genes involved in HLA class I-mediated antigen presentation, and 54% of these mutations were predicted to abrogate function. Mutations affecting the HLA class I transactivator NLRC5 were observed as a potential new immune evasion mechanism in 26% (6% abrogating) of the analyzed tumors. NLRC5 mutations in MMR-deficient cancers were associated with decreased levels of HLA class I antigen expression. In summary, the majority of MMR-deficient cancers display mutations interfering with HLA class I antigen presentation that reflect active immune surveillance and immunoselection during tumor development. Clinical studies focusing on immune checkpoint blockade in MSI cancer should account for the broad variety of immune evasion mechanisms as potential biomarkers of therapy success.

Involvement of p53 Mutation and Mismatch Repair Proteins Dysregulation in NNK-Induced Malignant Transformation of Human Bronchial Epithelial Cells

Directory of Open Access Journals (Sweden)

Ying Shen

2014-01-01

Full Text Available Genome integrity is essential for normal cellular functions and cell survival. Its instability can cause genetic aberrations and is considered as a hallmark of most cancers. To investigate the carcinogenesis process induced by tobacco-specific carcinogen NNK, we studied the dynamic changes of two important protectors of genome integrity, p53 and MMR system, in malignant transformation of human bronchial epithelial cells after NNK exposure. Our results showed that the expression of MLH1, one of the important MMR proteins, was decreased early and maintained the downregulation during the transformation in a histone modification involved and DNA methylation-independent manner. Another MMR protein PMS2 also displayed a declined expression while being in a later stage of transformation. Moreover, we conducted p53 mutation analysis and revealed a mutation at codon 273 which led to the replacement of arginine by histidine. With the mutation, DNA damage-induced activation of p53 was significantly impaired. We further reintroduced the wild-type p53 into the transformed cells, and the malignant proliferation can be abrogated by inducing cell cycle arrest and apoptosis. These findings indicate that p53 and MMR system play an important role in the initiation and progression of NNK-induced transformation, and p53 could be a potential therapeutic target for tobacco-related cancers.

Discrimination of Fearful and Angry Emotional Voices in Sleeping Human Neonates: a Study of the Mismatch Brain Responses

Directory of Open Access Journals (Sweden)

Dandan eZhang

2014-12-01

Full Text Available Appropriate processing of human voices with different threat-related emotions is of evolutionarily adaptive value for the survival of individuals. Nevertheless, it is still not clear whether the sensitivity to threat-related information is present at birth. Using an oddball paradigm, the current study investigated the neural correlates underlying automatic processing of emotional voices of fear and anger in sleeping neonates. Event-related potential data showed that the frontocentral scalp distribution of the neonatal brain could discriminate fearful voices from angry voices; the mismatch response (MMR was larger in response to the deviant stimuli of anger, compared with the standard stimuli of fear. Furthermore, this fear-anger MMR discrimination was observed only when neonates were in active sleep state. Although the neonates’ sensitivity to threat-related voices is not likely associated with a conceptual understanding of fearful and angry emotions, this special discrimination in early life may provide a foundation for later emotion and social cognition development.

Involvement of mismatch repair proteins in adaptive responses induced by N-methyl-N'-nitro-N-nitrosoguanidine against {gamma}-induced genotoxicity in human cells

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Ayumi; Sakamoto, Yasuteru; Masumura, Kenichi; Honma, Masamitsu [Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501 (Japan); Nohmi, Takehiko, E-mail: nohmi@nihs.go.jp [Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501 (Japan)

2011-08-01

Highlights: {yields} Health effects of radiation should be evaluated in combination with chemicals. {yields} Here, we show that MNNG suppresses radiation-induced genotoxicity in human cells. {yields} Mismatch repair proteins play critical roles in the apparent adaptive responses. {yields} Chemical exposure may modulate radiation-induced genotoxicity in humans. - Abstract: As humans are exposed to a variety of chemical agents as well as radiation, health effects of radiation should be evaluated in combination with chemicals. To explore combined genotoxic effects of radiation and chemicals, we examined modulating effects of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a direct-acting methylating agent, against genotoxicity of {gamma}-radiation. Human lymphoblastoid TK6 cells and its mismatch-deficient derivative, i.e., MT1 cells, were treated with MNNG for 24 h before they were exposed to {gamma}-irradiation at a dose of 1.0 Gy, and the resulting genotoxicity was examined. In TK6 cells, the pretreatments with MNNG at low doses suppressed frequencies of the thymidine kinase (TK) gene mutation and micronucleus (MN) formation induced by {gamma}-irradiation and thus the dose responses of TK and MN assays were U-shaped along with the pretreatment doses of MNNG. In contrast, the genotoxic effects of MNNG and {gamma}-irradiation were additive in MT1 cells and the frequencies of TK mutations and MN induction increased along with the doses of MNNG. Apoptosis induced by {gamma}-radiation was suppressed by the pretreatments in TK6 cells, but not in MT1 cells. The expression of p53 was induced and cell cycle was delayed at G2/M phase in TK6, but not in MT1 cells, by the treatments with MNNG. These results suggest that pretreatments of MNNG at low doses suppress genotoxicity of {gamma}-radiation in human cells and also that mismatch repair proteins are involved in the apparent adaptive responses.

Assessment of single nucleotide polymorphisms in screening 52 DNA repair and cell cycle control genes in Fanconi anemia patients

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Petrović Sandra

2015-01-01

Full Text Available Fanconi anemia (FA is a rare genetically heterogeneous disorder associated with bone marrow failure, birth defects and cancer susceptibility. Apart from the disease- causing mutations in FANC genes, the identification of specific DNA variations, such as single nucleotide polymorphisms (SNPs, in other candidate genes may lead to a better clinical description of this condition enabling individualized treatment with improvement of the prognosis. In this study, we have assessed 95 SNPs located in 52 key genes involved in base excision repair (BER, nucleotide excision repair (NER, mismatch repair (MMR, double strand break (DSB repair and cell cycle control using a DNA repair chip (Asper Biotech, Estonia which includes most of the common variants for the candidate genes. The SNP genotyping was performed in five FA-D2 patients and in one FA-A patient. The polymorphisms studied were synonymous (n=10, nonsynonymous (missense (n=52 and in non-coding regions of the genome (introns and 5 ‘and 3’ untranslated regions (UTR (n=33. Polymorphisms found at the homozygous state are selected for further analysis. Our results have shown a significant inter-individual variability among patients in the type and the frequency of SNPs and also elucidate the need for further studies of polymorphisms located in ATM, APEX APE 1, XRCC1, ERCC2, MSH3, PARP4, NBS1, BARD1, CDKN1B, TP53 and TP53BP1 which may be of great importance for better clinical description of FA. In addition, the present report recommends the use of SNPs as predictive and prognostic genetic markers to individualize therapy of FA patients. [Projekat Ministarstva nauke Republike Srbije, br. 173046

Distinct DNA-binding surfaces in the ATPase and linker domains of MutLγ determine its substrate specificities and exert separable functions in meiotic recombination and mismatch repair.

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Corentin Claeys Bouuaert

2017-05-01

Full Text Available Mlh1-Mlh3 (MutLγ is a mismatch repair factor with a central role in formation of meiotic crossovers, presumably through resolution of double Holliday junctions. MutLγ has DNA-binding, nuclease, and ATPase activities, but how these relate to one another and to in vivo functions are unclear. Here, we combine biochemical and genetic analyses to characterize Saccharomyces cerevisiae MutLγ. Limited proteolysis and atomic force microscopy showed that purified recombinant MutLγ undergoes ATP-driven conformational changes. In vitro, MutLγ displayed separable DNA-binding activities toward Holliday junctions (HJ and, surprisingly, single-stranded DNA (ssDNA, which was not predicted from current models. MutLγ bound DNA cooperatively, could bind multiple substrates simultaneously, and formed higher-order complexes. FeBABE hydroxyl radical footprinting indicated that the DNA-binding interfaces of MutLγ for ssDNA and HJ substrates only partially overlap. Most contacts with HJ substrates were located in the linker regions of MutLγ, whereas ssDNA contacts mapped within linker regions as well as the N-terminal ATPase domains. Using yeast genetic assays for mismatch repair and meiotic recombination, we found that mutations within different DNA-binding surfaces exert separable effects in vivo. For example, mutations within the Mlh1 linker conferred little or no meiotic phenotype but led to mismatch repair deficiency. Interestingly, mutations in the N-terminal domain of Mlh1 caused a stronger meiotic defect than mlh1Δ, suggesting that the mutant proteins retain an activity that interferes with alternative recombination pathways. Furthermore, mlh3Δ caused more chromosome missegregation than mlh1Δ, whereas mlh1Δ but not mlh3Δ partially alleviated meiotic defects of msh5Δ mutants. These findings illustrate functional differences between Mlh1 and Mlh3 during meiosis and suggest that their absence impinges on chromosome segregation not only via reduced

A monofunctional platinum complex coordinated to a rhodium metalloinsertor selectively binds mismatched DNA in the minor groove.

Science.gov (United States)

Weidmann, Alyson G; Barton, Jacqueline K

2015-10-05

We report the synthesis and characterization of a bimetallic complex derived from a new family of potent and selective metalloinsertors containing an unusual Rh-O axial coordination. This complex incorporates a monofunctional platinum center containing only one labile site for coordination to DNA, rather than two, and coordinates DNA nonclassically through adduct formation in the minor groove. This conjugate displays bifunctional, interdependent binding of mismatched DNA via metalloinsertion at a mismatch as well as covalent platinum binding. DNA sequencing experiments revealed that the preferred site of platinum coordination is not the traditional N7-guanine site in the major groove, but rather N3-adenine in the minor groove. The complex also displays enhanced cytotoxicity in mismatch repair-deficient and mismatch repair-proficient human colorectal carcinoma cell lines compared to the chemotherapeutic cisplatin, and it triggers cell death via an apoptotic pathway, rather than the necrotic pathway induced by rhodium metalloinsertors.

Étude de l'impact des microARNs sur la carcinogenèse des cancers colorectaux instables sur les séquences répétées microsatellites du génome

OpenAIRE

El-Murr , Nizar

2014-01-01

MSI tumor progression (Microsatellite Instability) is depicted as a multistage process that results from mutations generated by a process of genetic instability affecting mostly DNA tandem repeats (known as microsatellites). These mutations contribute to tumorigenesis when they disrupt the function of oncogenes or tumor suppressor genes. As a phenotypic trait, MSI is the consequence of DNA mismatch repair inactivation (MMR). This work focused on the role microRNAs might play in MSI tumorigene...

Evaluation of MMR Vaccination and Autism Link

Directory of Open Access Journals (Sweden)

J Gordon Millichap

2002-11-01

Full Text Available A retrospective cohort study of autism in all children born in Denmark from January 1991 through December 1998 and those receiving measles, mumps, and rubella (MMR vaccination is reported from the Danish Epidemiology Science Center, Aarhus, Denmark.

Clinical Significance and Prognostic Relevance of Microsatellite Instability in Sporadic Colorectal Cancer Patients

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Angelika Copija

2017-01-01

Full Text Available Microsatellite instability (MSI is a marker of the replication error phenotype. It is caused by impaired DNA mismatch repair processes (MMR, resulting in ineffectiveness of the mechanisms responsible for the DNA replication precision and postreplicative DNA repair. MSI underlies the pathogenesis of 10%–20% of colorectal cancer (CRC cases. The data about the potential value of MMR status as a predictive factor for 5-fluorouracil (FU-based chemotherapy remain unclear. According to National Comprehensive Cancer Network updated guidelines, MSI testing is recommended for all patients with stage II CRC because patients with MSI-H (high-frequency MSI tumour may have a good prognosis and obtain no benefit from 5-FU-based adjuvant chemotherapy. The significance of the MSI status as a predictive factor for patients with metastatic disease was not confirmed. The association between the MSI status and the efficacy of the therapy based on anti-programmed death-1 receptor inhibitors requires further studies.

Image reconstruction of mMR PET data using the open source software STIR

Energy Technology Data Exchange (ETDEWEB)

Markiewicz, Pawel [Centre for Medical Image Computing, University College London, London (United Kingdom); Thielemans, Kris [Institute of Nuclear Medicine, University College London, London (United Kingdom); Burgos, Ninon [Centre for Medical Image Computing, University College London, London (United Kingdom); Manber, Richard [Institute of Nuclear Medicine, University College London, London (United Kingdom); Jiao, Jieqing [Centre for Medical Image Computing, University College London, London (United Kingdom); Barnes, Anna [Institute of Nuclear Medicine, University College London, London (United Kingdom); Atkinson, David [Centre for Medical Imaging, University College London, London (United Kingdom); Arridge, Simon R [Centre for Medical Image Computing, University College London, London (United Kingdom); Hutton, Brian F [Institute of Nuclear Medicine, University College London, London (United Kingdom); Ourselin, Sébastien [Centre for Medical Image Computing, University College London, London (United Kingdom); Dementia Research Centre, University College London, London (United Kingdom)

2014-07-29

Simultaneous PET and MR acquisitions have now become possible with the new hybrid Biograph Molecular MR (mMR) scanner from Siemens. The purpose of this work is to create a platform for mMR 3D and 4D PET image reconstruction which would be freely accessible to the community as well as fully adjustable in order to obtain optimal images for a given research task in PET imaging. The proposed platform is envisaged to prove useful in developing novel and robust image bio-markers which could then be adapted for use on the mMR scanner.

Image reconstruction of mMR PET data using the open source software STIR

International Nuclear Information System (INIS)

Markiewicz, Pawel; Thielemans, Kris; Burgos, Ninon; Manber, Richard; Jiao, Jieqing; Barnes, Anna; Atkinson, David; Arridge, Simon R; Hutton, Brian F; Ourselin, Sébastien

2014-01-01

Simultaneous PET and MR acquisitions have now become possible with the new hybrid Biograph Molecular MR (mMR) scanner from Siemens. The purpose of this work is to create a platform for mMR 3D and 4D PET image reconstruction which would be freely accessible to the community as well as fully adjustable in order to obtain optimal images for a given research task in PET imaging. The proposed platform is envisaged to prove useful in developing novel and robust image bio-markers which could then be adapted for use on the mMR scanner.

Is hospital based MMR vaccination for children with egg allergy here to stay?

LENUS (Irish Health Repository)

Hawkes, C P

2010-01-01

Egg allergy is incorrectly considered to constitute a contraindication to MMR in the community, despite a long history of its safe administration to egg allergic children. The product insert perpetuates this misinformation but the Irish guidelines from the RCPI are unequivocal. We reviewed all paediatric cases vaccinated in our hospital in 2007-2008. Forty seven of 91 children receiving vaccinations in hospital, had been referred for MMR due to concerns regarding egg allergy. In 32% (n=15), GP referral for vaccination was made despite correspondence from the clinic advising routine vaccination in the community. Nineteen were second MMR immunisations, which should all have occurred in the community. Unnecessary hospital referral for MMR vaccination is an extra burden on hospital resources, and causes unwarranted anxiety amongst parents of children with egg allergy. A change in practice seems difficult to achieve, as many referrals happen despite individualised correspondence to GPs and other referring clinicians outlining the current guidelines.

Recent advances in DNA repair and recombination.

Science.gov (United States)

Iwanejko, L A; Jones, N J

1998-09-11

The subjects of the talks at this 1-day DNA Repair Network meeting, held at City University, London on December 15, 1997, encompassed a range of topics and reflected some of the current areas of research in the United Kingdom. Topics included DNA double-strand break repair, V(D)J recombination, DNA ligases, the RecQ family of helicases and Bloom's syndrome, UVB and immunosuppression, the repair of oxidative damage and mismatch repair mechanisms.

Uncertainties in the Management of a Lynch Syndrome Patient: A Case Report

OpenAIRE

Campos, Sara; Amaro, Pedro; Cunha, Inês; Fraga, João; Cipriano, Maria Augusta; Tomé, Luís

2017-01-01

Introduction: Lynch syndrome (LS), the most common hereditary colorectal cancer syndrome, is characterized by mutations in mismatch repair (MMR) genes leading to an increased cancer risk, namely colorectal cancer. Case: In the context of surveillance colonoscopy, a 40-mm flat lesion (0-IIa+b, Paris classification) was identified and submitted to piecemeal mucosal endoscopic resection in a 64-year-old LS patient with an MLH1 germline mutation (262delATC) and two previous segmental resections d...

Association of apolipoprotein E polymorphisms and dietary factors in colorectal cancer

OpenAIRE

Mrkonjic, M; Chappell, E; Pethe, V V; Manno, M; Daftary, D; Greenwood, C M; Gallinger, S; Zanke, B W; Knight, J A; Bapat, B

2009-01-01

ApoE single nucleotide polymorphisms (SNPs) Cys112Arg (Epsilon-4), and Arg158Cys (Epsilon-2) have been implicated in cardiovascular and Alzheimer's disease, but their role in colorectal cancer (CRC) has not been extensively studied. We investigated whether ApoE polymorphisms alone or in combination with dietary factors selectively contribute to mismatch-repair (MMR) proficient (microsatellite stable/low or MSS/L) vs deficient (microsatellite unstable or MSI-H) CRCs. We carried out a case?cont...

DNA repair deficiency in neurodegeneration

DEFF Research Database (Denmark)

Jeppesen, Dennis Kjølhede; Bohr, Vilhelm A; Stevnsner, Tinna V.

2011-01-01

Deficiency in repair of nuclear and mitochondrial DNA damage has been linked to several neurodegenerative disorders. Many recent experimental results indicate that the post-mitotic neurons are particularly prone to accumulation of unrepaired DNA lesions potentially leading to progressive...... neurodegeneration. Nucleotide excision repair is the cellular pathway responsible for removing helix-distorting DNA damage and deficiency in such repair is found in a number of diseases with neurodegenerative phenotypes, including Xeroderma Pigmentosum and Cockayne syndrome. The main pathway for repairing oxidative...... base lesions is base excision repair, and such repair is crucial for neurons given their high rates of oxygen metabolism. Mismatch repair corrects base mispairs generated during replication and evidence indicates that oxidative DNA damage can cause this pathway to expand trinucleotide repeats, thereby...

Three molecular pathways model colorectal carcinogenesis in Lynch syndrome.

Science.gov (United States)

Ahadova, Aysel; Gallon, Richard; Gebert, Johannes; Ballhausen, Alexej; Endris, Volker; Kirchner, Martina; Stenzinger, Albrecht; Burn, John; von Knebel Doeberitz, Magnus; Bläker, Hendrik; Kloor, Matthias

2018-07-01

Lynch syndrome is caused by germline mutations of DNA mismatch repair (MMR) genes. MMR deficiency has long been regarded as a secondary event in the pathogenesis of Lynch syndrome colorectal cancers. Recently, this concept has been challenged by the discovery of MMR-deficient crypt foci in the normal mucosa. We aimed to reconstruct colorectal carcinogenesis in Lynch syndrome by collecting molecular and histology evidence from Lynch syndrome adenomas and carcinomas. We determined the frequency of MMR deficiency in adenomas from Lynch syndrome mutation carriers by immunohistochemistry and by systematic literature analysis. To trace back the pathways of pathogenesis, histological growth patterns and mutational signatures were analyzed in Lynch syndrome colorectal cancers. Literature and immunohistochemistry analysis demonstrated MMR deficiency in 491 (76.7%) out of 640 adenomas (95% CI: 73.3% to 79.8%) from Lynch syndrome mutation carriers. Histologically normal MMR-deficient crypts were found directly adjacent to dysplastic adenoma tissue, proving their role as tumor precursors in Lynch syndrome. Accordingly, mutation signature analysis in Lynch colorectal cancers revealed that KRAS and APC mutations commonly occur after the onset of MMR deficiency. Tumors lacking evidence of polypous growth frequently presented with CTNNB1 and TP53 mutations. Our findings demonstrate that Lynch syndrome colorectal cancers can develop through three pathways, with MMR deficiency commonly representing an early and possibly initiating event. This underlines that targeting MMR-deficient cells by chemoprevention or vaccines against MMR deficiency-induced frameshift peptide neoantigens holds promise for tumor prevention in Lynch syndrome. © 2018 UICC.

Human colon cancer profiles show differential microRNA expression depending on mismatch repair status and are characteristic of undifferentiated proliferative states

International Nuclear Information System (INIS)

Sarver, Aaron L; Cunningham, Julie M; Subramanian, Subbaya; Wang, Liang; Smyrk, Tom C; Rodrigues, Cecilia MP; Thibodeau, Stephen N; Steer, Clifford J; French, Amy J; Borralho, Pedro M; Thayanithy, Venugopal; Oberg, Ann L; Silverstein, Kevin AT; Morlan, Bruce W; Riska, Shaun M; Boardman, Lisa A

2009-01-01

Colon cancer arises from the accumulation of multiple genetic and epigenetic alterations to normal colonic tissue. microRNAs (miRNAs) are small, non-coding regulatory RNAs that post-transcriptionally regulate gene expression. Differential miRNA expression in cancer versus normal tissue is a common event and may be pivotal for tumor onset and progression. To identify miRNAs that are differentially expressed in tumors and tumor subtypes, we carried out highly sensitive expression profiling of 735 miRNAs on samples obtained from a statistically powerful set of tumors (n = 80) and normal colon tissue (n = 28) and validated a subset of this data by qRT-PCR. Tumor specimens showed highly significant and large fold change differential expression of the levels of 39 miRNAs including miR-135b, miR-96, miR-182, miR-183, miR-1, and miR-133a, relative to normal colon tissue. Significant differences were also seen in 6 miRNAs including miR-31 and miR-592, in the direct comparison of tumors that were deficient or proficient for mismatch repair. Examination of the genomic regions containing differentially expressed miRNAs revealed that they were also differentially methylated in colon cancer at a far greater rate than would be expected by chance. A network of interactions between these miRNAs and genes associated with colon cancer provided evidence for the role of these miRNAs as oncogenes by attenuation of tumor suppressor genes. Colon tumors show differential expression of miRNAs depending on mismatch repair status. miRNA expression in colon tumors has an epigenetic component and altered expression that may reflect a reversion to regulatory programs characteristic of undifferentiated proliferative developmental states

Association between perfluoroalkyl substance exposure and asthma and allergic disease in children as modified by MMR vaccination.

Science.gov (United States)

Timmermann, Clara Amalie Gade; Budtz-Jørgensen, Esben; Jensen, Tina Kold; Osuna, Christa Elyse; Petersen, Maria Skaalum; Steuerwald, Ulrike; Nielsen, Flemming; Poulsen, Lars K; Weihe, Pál; Grandjean, Philippe

2017-12-01

Perfluoroalkyl substances (PFASs) are highly persistent chemicals that might be associated with asthma and allergy, but the associations remain unclear. Therefore, this study examined whether pre- and postnatal PFAS exposure was associated with childhood asthma and allergy. Measles, mumps, and rubella (MMR) vaccination in early life may have a protective effect against asthma and allergy, and MMR vaccination is therefore taken into account when evaluating these associations. In a cohort of Faroese children whose mothers were recruited during pregnancy, serum concentrations of five PFASs - Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) - were measured at three timepoints (maternal serum in pregnancy week 34-36 and child serum at ages 5 and 13 years) and their association with immunoglobulin E (IgE) (cord blood and at age 7 years) and asthma/allergic diseases (questionnaires at ages 5 and 13 years and skin prick test at age 13 years) was determined. A total of 559 children were included in the analyses. Interactions with MMR vaccination were evaluated. Among 22 MMR-unvaccinated children, higher levels of the five PFASs at age 5 years were associated with increased odds of asthma at ages 5 and 13. The associations were reversed among MMR-vaccinated children. Prenatal PFAS exposure was not associated with childhood asthma or allergic diseases regardless of MMR vaccination status. In conclusion, PFAS exposure at age 5 was associated with increased risk of asthma among a small subgroup of MMR-unvaccinated children but not among MMR-vaccinated children. While PFAS exposure may impact immune system functions, this study suggests that MMR vaccination might be a potential effect-modifier.

The Effect of Basepair Mismatch on DNA Strand Displacement.

Science.gov (United States)

Broadwater, D W Bo; Kim, Harold D

2016-04-12

DNA strand displacement is a key reaction in DNA homologous recombination and DNA mismatch repair and is also heavily utilized in DNA-based computation and locomotion. Despite its ubiquity in science and engineering, sequence-dependent effects of displacement kinetics have not been extensively characterized. Here, we measured toehold-mediated strand displacement kinetics using single-molecule fluorescence in the presence of a single basepair mismatch. The apparent displacement rate varied significantly when the mismatch was introduced in the invading DNA strand. The rate generally decreased as the mismatch in the invader was encountered earlier in displacement. Our data indicate that a single base pair mismatch in the invader stalls branch migration and displacement occurs via direct dissociation of the destabilized incumbent strand from the substrate strand. We combined both branch migration and direct dissociation into a model, which we term the concurrent displacement model, and used the first passage time approach to quantitatively explain the salient features of the observed relationship. We also introduce the concept of splitting probabilities to justify that the concurrent model can be simplified into a three-step sequential model in the presence of an invader mismatch. We expect our model to become a powerful tool to design DNA-based reaction schemes with broad functionality. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Quantitative comparison of PET performance—Siemens Biograph mCT and mMR

Energy Technology Data Exchange (ETDEWEB)

Karlberg, Anna M.; Sæther, Oddbjørn [Department of Radiology and Nuclear Medicine, St. Olavs Hospital, Olav Kyrres gt 17, 7006 Trondheim (Norway); Eikenes, Live [Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Postbox 8905, 7491 Trondheim (Norway); Goa, Pål Erik [Department of Radiology and Nuclear Medicine, St. Olavs Hospital, Olav Kyrres gt 17, 7006 Trondheim (Norway); Department of Physics, Norwegian University of Science and Technology, Trondheim (Norway)

2016-02-25

Integrated clinical whole-body PET/MR systems were introduced in 2010. In order to bring this technology into clinical usage, it is of great importance to compare the performance with the well-established PET/CT. The aim of this study was to evaluate PET performance, with focus on image quality, on Siemens Biograph mMR (PET/MR) and Siemens Biograph mCT (PET/CT). A direct quantitative comparison of the performance characteristics between the mMR and mCT system was performed according to National Electrical Manufacturers Association (NEMA) NU 2-2007 protocol. Spatial resolution, sensitivity, count rate and image quality were evaluated. The evaluation was supplemented with additional standardized uptake value (SUV) measurements. The spatial resolution was similar for the two systems. Average sensitivity was higher for the mMR (13.3 kcps/MBq) compared to the mCT system (10.0 kcps/MBq). Peak noise equivalent count rate (NECR) was slightly higher for the mMR (196 kcps @ 24.4 kBq/mL) compared to the mCT (186 kcps @ 30.1 kBq/mL). Scatter fractions in the clinical activity concentration range yielded lower values for the mCT (34.9 %) compared to those for the mMR (37.0 %). Best image quality of the systems resulted in approximately the same mean hot sphere contrast and a difference of 19 percentage points (pp) in mean cold contrast, in favour of the mCT. In general, point spread function (PSF) increased hot contrast and time of flight (TOF) increased both hot and cold contrast. Highest hot contrast for the smallest sphere (10 mm) was achieved with the combination of TOF and PSF on the mCT. Lung residual error was higher for the mMR (22 %) than that for the mCT (17 %), with no effect of PSF. With TOF, lung residual error was reduced to 8 % (mCT). SUV was accurate for both systems, but PSF caused overestimations for the 13-, 17- and 22-mm spheres. Both systems proved good performance characteristics, and the PET image quality of the mMR was close to that of the m

Cadmium(Cd)-induced oxidative stress down-regulates the gene expression of DNA mismatch recognition proteins MutS homolog 2 (MSH2) and MSH6 in zebrafish (Danio rerio) embryos

Energy Technology Data Exchange (ETDEWEB)

Hsu, Todd, E-mail: toddhsu@mail.ntou.edu.tw [Institute of Bioscience and Biotechnology and Center of Excellence for Marine Bioenvironment and Biotechnology, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Huang, Kuan-Ming; Tsai, Huei-Ting; Sung, Shih-Tsung; Ho, Tsung-Nan [Institute of Bioscience and Biotechnology and Center of Excellence for Marine Bioenvironment and Biotechnology, National Taiwan Ocean University, Keelung 20224, Taiwan (China)

2013-01-15

DNA mismatch repair (MMR) of simple base mismatches and small insertion-deletion loops in eukaryotes is initiated by the binding of the MutS homolog 2 (MSH2)-MSH6 heterodimer to mismatched DNA. Cadmium (Cd) is a genotoxic heavy metal that has been recognized as a human carcinogen. Oxidant stress and inhibition of DNA repair have been proposed as major factors underlying Cd genotoxicity. Our previous studies indicated the ability of Cd to disturb the gene expression of MSH6 in zebrafish (Danio rerio) embryos. This study was undertaken to explore if Cd-induced oxidative stress down-regulated MSH gene activities. Following the exposure of zebrafish embryos at 1 h post fertilization (hpf) to sublethal concentrations of Cd at 3-5 {mu}M for 4 or 9 h, a parallel down-regulation of MSH2, MSH6 and Cu/Zn superoxide dismutase (Cu/Zn-SOD) gene expression was detected by real-time RT-PCR and the expression levels were 40-50% of control after a 9-h exposure. Cd exposure also induced oxidative stress, yet no inhibition of catalase gene activity was observed. Whole mount in situ hybridization revealed a wide distribution of msh6 mRNA in the head regions of 10 hpf embryos and pretreatment of embryos with antioxidants butylhydroxytoluene (BHT), D-mannitol or N-acetylcysteine (NAC) at 1-10 {mu}M restored Cd-suppressed msh6 expression. QPCR confirmed the protective effects of antioxidants on Cd-suppressed msh2/msh6 mRNA production. Down-regulated MSH gene activities reaching about 50% of control were also induced in embryos exposed to paraquat, a reactive oxygen species (ROS)-generating herbicide, or hydrogen peroxide at 200 {mu}M. Hence, Cd at sublethal levels down-regulates msh2/msh6 expression primarily via ROS as signaling molecules. The transcriptional activation of human msh6 is known to be fully dependent on the specificity factor 1 (Sp1). Cd failed to inhibit the DNA binding activity of zebrafish Sp1 unless at lethal concentrations based on band shift assay, therefore

Cross-calibration of the Siemens mMR

DEFF Research Database (Denmark)

Keller, Sune H; Jakoby, Björn; Svalling, Susanne

2016-01-01

BACKGROUND: We present a quick and easy method to perform quantitatively accurate PET scans of typical water-filled PET plastic shell phantoms on the Siemens Biograph mMR PET/MR system. We perform regular cross-calibrations (Xcal) of our PET systems, including the PET/MR, using a Siemens mCT water...

Topoisomerase-1 and -2A gene copy numbers are elevated in mismatch repair-proficient colorectal cancers

DEFF Research Database (Denmark)

Sønderstrup, Ida Marie Heeholm; Nygård, Sune Boris; Poulsen, Tim Svenstrup

2015-01-01

to MMR status by immunohistochemical analysis using validated antibodies for MLH1, MLH2, MSH6 and PMS2, and information on TOP1, CEN20, TOP2A and CEN17 status was previously published for this cohort. RESULTS: The observed TOP1 gene copy numbers in the 36 CRC test cohort were significantly greater (p

Nuclear localization of human DNA mismatch repair protein exonuclease 1 (hEXO1)

DEFF Research Database (Denmark)

Knudsen, Nina Østergaard; Nielsen, Finn Cilius; Vinther, Lena

2007-01-01

interaction with hMLH1 and we show that defective nuclear localization of hEXO1 mutant proteins could be rescued by hMLH1 or hMSH2. Both hEXO1 and hMLH1 form complexes with the nuclear import factors importin beta/alpha1,3,7 whereas hMSH2 specifically recognizes importin beta/alpha3. Taken together, we infer...... that hEXO1, hMLH1 and hMSH2 form complexes and are imported to the nucleus together, and that redundant NLS import signals in the proteins may safeguard nuclear import and thereby MMR activity....

Mlh1 is required for female fertility in Drosophila melanogaster: An outcome of effects on meiotic crossing over, ovarian follicles and egg activation.

Science.gov (United States)

Vimal, Divya; Kumar, Saurabh; Pandey, Ashutosh; Sharma, Divya; Saini, Sanjay; Gupta, Snigdha; Ravi Ram, Kristipati; Chowdhuri, Debapratim Kar

2018-03-01

Mismatch repair (MMR) system, a conserved DNA repair pathway, plays crucial role in DNA recombination and is involved in gametogenesis. The impact of alterations in MMR family of proteins (bacterial MutS and MutL homologues) on mammalian fertility is well documented. However, an insight to the role of MMR in reproduction of non-mammalian organisms is limited. Hence, in the present study, we analysed the impact of mlh1 (a MutL homologue) on meiotic crossing over/recombination and fertility in a genetically tractable model, Drosophila melanogaster. Using mlh1 e00130 hypomorphic allele, we report female specific adverse reproductive outcome for reduced mlh1 in Drosophila: mlh1 e00130 homozygous females had severely reduced fertility while males were fertile. Further, mlh1 e00130 females contained small ovaries with large number of early stages as well as significantly reduced mature oocytes, and laid fewer eggs, indicating discrepancies in egg production and ovulation. These observations contrast the sex independent and/or male specific sterility and normal follicular development as well as ovulation reported so far for MMR family proteins in mammals. However, analogous to the role(s) of mlh1 in meiotic crossing over and DNA repair processes underlying mammalian fertility, ovarian follicles from mlh1 e00130 females contained significantly increased DNA double strand breaks (DSBs) and reduced synaptonemal complex foci. In addition, large proportion of fertilized eggs display discrepancies in egg activation and fail to proceed beyond stage 5 of embryogenesis. Hence, reduction of the Mlh1 protein level leads to defective oocytes that fail to complete embryogenesis after fertilization thereby reducing female fertility. Copyright © 2017 Elsevier GmbH. All rights reserved.

Isolated loss of PMS2 immunohistochemical expression is frequently caused by heterogeneous MLH1 promoter hypermethylation in Lynch syndrome screening for endometrial cancer patients

OpenAIRE

Kato, Aya; Sato, Naoki; Sugawara, Tae; Takahashi, Kazue; Kito, Masahiko; Makino, Kenichi; Sato, Toshiharu; Shimizu, Dai; Shirasawa, Hiromitu; Miura, Hiroshi; Sato, Wataru; Kumazawa, Yukiyo; Sato, Akira; Kumagai, Jin; Terada, Yukihiro

2016-01-01

Lynch syndrome (LS) is an autosomal dominant inherited disorder mainly caused by a germline mutation in the DNA mismatch repair (MMR) genes (MLH1, MSH2, MSH6, PMS2) and is associated with increased risk of various cancers, particularly colorectal cancer and endometrial cancer (EC). Women with LS account for 2–6% of EC patients; it is clinically important to identify LS in such individuals for predicting and/or preventing additional LS-associated cancers. PMS2 germline mutation ...

Milestones of Lynch syndrome: 1895-2015.

Science.gov (United States)

Lynch, Henry T; Snyder, Carrie L; Shaw, Trudy G; Heinen, Christopher D; Hitchins, Megan P

2015-03-01

Lynch syndrome, which is now recognized as the most common hereditary colorectal cancer condition, is characterized by the predisposition to a spectrum of cancers, primarily colorectal cancer and endometrial cancer. We chronicle over a century of discoveries that revolutionized the diagnosis and clinical management of Lynch syndrome, beginning in 1895 with Warthin's observations of familial cancer clusters, through the clinical era led by Lynch and the genetic era heralded by the discovery of causative mutations in mismatch repair (MMR) genes, to ongoing challenges.

Predictive models for mutations in mismatch repair genes: implication for genetic counseling in developing countries

Energy Technology Data Exchange (ETDEWEB)

Monteiro Santos, Erika Maria [Graduation Program, AC Camargo Hospital, Sao Paulo (Brazil); International Center of Research and Training (CIPE), AC Camargo Hospital, Sao Paulo (Brazil); Silva Junior, Wilson Araujo da [Sao Paulo University, Department of Genetics, Medical School of Ribeirao Preto, Ribeirao Preto (Brazil); Carraro, Dirce Maria [Graduation Program, AC Camargo Hospital, Sao Paulo (Brazil); International Center of Research and Training (CIPE), AC Camargo Hospital, Sao Paulo (Brazil); Rossi, Benedito Mauro; Valentin, Mev Dominguez [Graduation Program, AC Camargo Hospital, Sao Paulo (Brazil); Carneiro, Felipe [Graduation Program, AC Camargo Hospital, Sao Paulo (Brazil); International Center of Research and Training (CIPE), AC Camargo Hospital, Sao Paulo (Brazil); Oliveira, Ligia Petrolini de [Graduation Program, AC Camargo Hospital, Sao Paulo (Brazil); Oliveira Ferreira, Fabio de; Junior, Samuel Aguiar [Graduation Program, AC Camargo Hospital, Sao Paulo (Brazil); Hereditary Colorectal Cancer Registry, AC Camargo Hospital, Sao Paulo (Brazil); Nakagawa, Wilson Toshihiko [Hereditary Colorectal Cancer Registry, AC Camargo Hospital, Sao Paulo (Brazil); Gomy, Israel [Graduation Program, AC Camargo Hospital, Sao Paulo (Brazil); Sao Paulo University, Department of Genetics, Medical School of Ribeirao Preto, Ribeirao Preto (Brazil); Faria Ferraz, Victor Evangelista de [Sao Paulo University, Department of Genetics, Medical School of Ribeirao Preto, Ribeirao Preto (Brazil)

2012-02-09

Lynch syndrome (LS) is the most common form of inherited predisposition to colorectal cancer (CRC), accounting for 2-5% of all CRC. LS is an autosomal dominant disease characterized by mutations in the mismatch repair genes mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), postmeiotic segregation increased 1 (PMS1), post-meiotic segregation increased 2 (PMS2) and mutS homolog 6 (MSH6). Mutation risk prediction models can be incorporated into clinical practice, facilitating the decision-making process and identifying individuals for molecular investigation. This is extremely important in countries with limited economic resources. This study aims to evaluate sensitivity and specificity of five predictive models for germline mutations in repair genes in a sample of individuals with suspected Lynch syndrome. Blood samples from 88 patients were analyzed through sequencing MLH1, MSH2 and MSH6 genes. The probability of detecting a mutation was calculated using the PREMM, Barnetson, MMRpro, Wijnen and Myriad models. To evaluate the sensitivity and specificity of the models, receiver operating characteristic curves were constructed. Of the 88 patients included in this analysis, 31 mutations were identified: 16 were found in the MSH2 gene, 15 in the MLH1 gene and no pathogenic mutations were identified in the MSH6 gene. It was observed that the AUC for the PREMM (0.846), Barnetson (0.850), MMRpro (0.821) and Wijnen (0.807) models did not present significant statistical difference. The Myriad model presented lower AUC (0.704) than the four other models evaluated. Considering thresholds of ≥ 5%, the models sensitivity varied between 1 (Myriad) and 0.87 (Wijnen) and specificity ranged from 0 (Myriad) to 0.38 (Barnetson). The Barnetson, PREMM, MMRpro and Wijnen models present similar AUC. The AUC of the Myriad model is statistically inferior to the four other models.

Predictive models for mutations in mismatch repair genes: implication for genetic counseling in developing countries

International Nuclear Information System (INIS)

Monteiro Santos, Erika Maria; Silva Junior, Wilson Araujo da; Carraro, Dirce Maria; Rossi, Benedito Mauro; Valentin, Mev Dominguez; Carneiro, Felipe; Oliveira, Ligia Petrolini de; Oliveira Ferreira, Fabio de; Junior, Samuel Aguiar; Nakagawa, Wilson Toshihiko; Gomy, Israel; Faria Ferraz, Victor Evangelista de

2012-01-01

Lynch syndrome (LS) is the most common form of inherited predisposition to colorectal cancer (CRC), accounting for 2-5% of all CRC. LS is an autosomal dominant disease characterized by mutations in the mismatch repair genes mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), postmeiotic segregation increased 1 (PMS1), post-meiotic segregation increased 2 (PMS2) and mutS homolog 6 (MSH6). Mutation risk prediction models can be incorporated into clinical practice, facilitating the decision-making process and identifying individuals for molecular investigation. This is extremely important in countries with limited economic resources. This study aims to evaluate sensitivity and specificity of five predictive models for germline mutations in repair genes in a sample of individuals with suspected Lynch syndrome. Blood samples from 88 patients were analyzed through sequencing MLH1, MSH2 and MSH6 genes. The probability of detecting a mutation was calculated using the PREMM, Barnetson, MMRpro, Wijnen and Myriad models. To evaluate the sensitivity and specificity of the models, receiver operating characteristic curves were constructed. Of the 88 patients included in this analysis, 31 mutations were identified: 16 were found in the MSH2 gene, 15 in the MLH1 gene and no pathogenic mutations were identified in the MSH6 gene. It was observed that the AUC for the PREMM (0.846), Barnetson (0.850), MMRpro (0.821) and Wijnen (0.807) models did not present significant statistical difference. The Myriad model presented lower AUC (0.704) than the four other models evaluated. Considering thresholds of ≥ 5%, the models sensitivity varied between 1 (Myriad) and 0.87 (Wijnen) and specificity ranged from 0 (Myriad) to 0.38 (Barnetson). The Barnetson, PREMM, MMRpro and Wijnen models present similar AUC. The AUC of the Myriad model is statistically inferior to the four other models

Localization of MLH3 at the Centrosomes

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Lennart M. Roesner

2014-08-01

Full Text Available Mutations in human DNA mismatch repair (MMR genes are commonly associated with hereditary nonpolyposis colorectal cancer (HNPCC. MLH1 protein heterodimerizes with PMS2, PMS1, and MLH3 to form MutLα, MutLβ, and MutLγ, respectively. We reported recently stable expression of GFP-linked MLH3 in human cell lines. Monitoring these cell lines during the cell cycle using live cell imaging combined with confocal microscopy, we detected accumulation of MLH3 at the centrosomes. Fluorescence recovery after photobleaching (FRAP revealed high mobility and fast exchange rates at the centrosomes as it has been reported for other DNA repair proteins. MLH3 may have a role in combination with other repair proteins in the control of centrosome numbers.

Elucidating the clinical significance of two PMS2 missense variants coexisting in a family fulfilling hereditary cancer criteria.

Science.gov (United States)

González-Acosta, Maribel; Del Valle, Jesús; Navarro, Matilde; Thompson, Bryony A; Iglesias, Sílvia; Sanjuan, Xavier; Paúles, María José; Padilla, Natàlia; Fernández, Anna; Cuesta, Raquel; Teulé, Àlex; Plotz, Guido; Cadiñanos, Juan; de la Cruz, Xavier; Balaguer, Francesc; Lázaro, Conxi; Pineda, Marta; Capellá, Gabriel

2017-10-01

The clinical spectrum of germline mismatch repair (MMR) gene variants continues increasing, encompassing Lynch syndrome, Constitutional MMR Deficiency (CMMRD), and the recently reported MSH3-associated polyposis. Genetic diagnosis of these hereditary cancer syndromes is often hampered by the presence of variants of unknown significance (VUS) and overlapping phenotypes. Two PMS2 VUS, c.2149G>A (p.V717M) and c.2444C>T (p.S815L), were identified in trans in one individual diagnosed with early-onset colorectal cancer (CRC) who belonged to a family fulfilling clinical criteria for hereditary cancer. Clinico-pathological data, multifactorial likelihood calculations and functional analyses were used to refine their clinical significance. Likelihood analysis based on cosegregation and tumor data classified the c.2444C>T variant as pathogenic, which was supported by impaired MMR activity associated with diminished protein expression in functional assays. Conversely, the c.2149G>A variant displayed MMR proficiency and protein stability. These results, in addition to the conserved PMS2 expression in normal tissues and the absence of germline microsatellite instability (gMSI) in the biallelic carrier ruled out a CMMRD diagnosis. The use of comprehensive strategies, including functional and clinico-pathological information, is mandatory to improve the clinical interpretation of naturally occurring MMR variants. This is critical for appropriate clinical management of cancer syndromes associated to MMR gene mutations.

Infrequent widespread microsatellite instability in hepatocellular carcinomas.

Science.gov (United States)

Yamamoto, H; Itoh, F; Fukushima, H; Kaneto, H; Sasaki, S; Ohmura, T; Satoh, T; Karino, Y; Endo, T; Toyota, J; Imai, K

2000-03-01

Widespread or high-frequency microsatellite instability (MSI) due to the defective DNA mismatch repair (MMR) occurs in the majority of hereditary non-polyposis colorectal cancer and a subset of sporadic malignant tumors. The incidence of MSI and underlying DNA MMR defects have been well characterized in gastrointestinal carcinogenesis, but not in hepatocarcinogenesis. To address the issue, we analyzed 55 Japanese hepatocellular carcinomas using several indicators of DNA MMR defects, such as microsatellite analysis, loss of heterozygosity (LOH) and mutation analysis of MMR genes, methylation of hMLH1 promoter, and frameshift mutations of mononucleotide repeat sequences within possible target genes. Mutation of beta2-microglobulin gene, which is presumably involved in MSI-positive tumor cell escape from immune surveillance was also examined. Some of these analyses were also carried out in 9 human liver cancer cell lines. None of the 3 quasi-monomorphic mononucleotide markers sensitive for MSI, BAT26, BAT25, and BAT34C4 presented shortened unstable alleles in any of the carcinoma, cirrhosis, chronic hepatitis tissues, or cell lines. LOH at MMR genes was infrequent (4.4 approximately 7.1%), and no mutations were detected. Neither hMLH1 hypermethylation nor frameshift mutation in the target genes was detected. No mutations were found in beta2-microglobulin. Widespread MSI due to the defective DNA MMR appears to play little if any part in Japanese hepatocarcinogenesis.

Cross calibration of the Siemens mMR: easily acquired accurate PET phantom measurements, long term stability and reproducibility

Energy Technology Data Exchange (ETDEWEB)

Keller, Sune H [Rigshospitalet, University of Copenhagen, Copenhagen (Denmark); Jakoby, Bjorn [University of Surrey, Guildford (United Kingdom); Hansen, Adam Espe; Svalling, Susanne; Klausen, Thomas L [Rigshospitalet, University of Copenhagen, Copenhagen (Denmark)

2015-05-18

We present a quick and easy method to perform quantitatively accurate PET scans of typical water-filled PET plastic shell phantoms on the Siemens mMR PET/MR scanner. We perform regular cross calibrations (Xcals) of our PET scanners, including the Siemens mMR PET/MR, with a Siemens mCT water phantom. We evaluate the mMR cross calibration stability over a 3-year period. Recently, the mMR software (VB20P) offered the option of using predefined μ-maps. We evaluated this option by using either the predefined μ-map of the long mMR water phantom or a system-integrated user defined CT-based μ-map of the mCT water phantom used for Xcal. On 54 cross calibrations that were acquired over 3 years, the mMR on average underestimated the concentration by 16% due to the use of MR-based μ-maps. The mMR produced the narrowest range and lowest standard deviation of the Xcal ratios, implying it and is the most stable of the 6 scanners included in this study over a 3 year period. With correctly segmented μ-maps, the mMR produced Xcal ratios of 1.00-1.02, well within the acceptance range [0.95-1.05]. Measuring the concentration in a centrally placed cylindrical VOI allows for some robustness against misregistration of the μ-maps but it should be no more than a few millimeters in the x-y plane, while the tolerance is larger on the z-axis (when, as always with PET, keeping clear of the axial edges of the FOV). The mMR is the most stable scanner in this study and the mean underestimation is no longer an issue with the easily accessible μ-map, which in all 7 tests resulted in correct Xcal ratios. We will share the user defined μ-map of the mCT phantom and the protocol with interested mMR users.

Cross calibration of the Siemens mMR: easily acquired accurate PET phantom measurements, long term stability and reproducibility

International Nuclear Information System (INIS)

Keller, Sune H; Jakoby, Bjorn; Hansen, Adam Espe; Svalling, Susanne; Klausen, Thomas L

2015-01-01

We present a quick and easy method to perform quantitatively accurate PET scans of typical water-filled PET plastic shell phantoms on the Siemens mMR PET/MR scanner. We perform regular cross calibrations (Xcals) of our PET scanners, including the Siemens mMR PET/MR, with a Siemens mCT water phantom. We evaluate the mMR cross calibration stability over a 3-year period. Recently, the mMR software (VB20P) offered the option of using predefined μ-maps. We evaluated this option by using either the predefined μ-map of the long mMR water phantom or a system-integrated user defined CT-based μ-map of the mCT water phantom used for Xcal. On 54 cross calibrations that were acquired over 3 years, the mMR on average underestimated the concentration by 16% due to the use of MR-based μ-maps. The mMR produced the narrowest range and lowest standard deviation of the Xcal ratios, implying it and is the most stable of the 6 scanners included in this study over a 3 year period. With correctly segmented μ-maps, the mMR produced Xcal ratios of 1.00-1.02, well within the acceptance range [0.95-1.05]. Measuring the concentration in a centrally placed cylindrical VOI allows for some robustness against misregistration of the μ-maps but it should be no more than a few millimeters in the x-y plane, while the tolerance is larger on the z-axis (when, as always with PET, keeping clear of the axial edges of the FOV). The mMR is the most stable scanner in this study and the mean underestimation is no longer an issue with the easily accessible μ-map, which in all 7 tests resulted in correct Xcal ratios. We will share the user defined μ-map of the mCT phantom and the protocol with interested mMR users.

Sporadic colorectal polyps and mismatch repair proteins

Directory of Open Access Journals (Sweden)

Mahsa Molaei

2011-01-01

Full Text Available Background: Colorectal cancers often arise from benign polyps. Adenomatous polyps and serrated polyps progress step by step to adenocarcinoma and change into malignant cancers. Genetic and epigenetic changes have correlation with specific stages of polyp-adenocarcinoma progression and colorectal cancer histopathological changes. Aims: In this study we used immunohistochemistry (IHC staining in sporadic colorectal polyps to assay functional status of MLH1, MSH2, MSH6, and PMS2 proteins, to track genetic/epigenetic roles of this issue in our patients. Materials and Methods: In this cross-sectional study we assessed all patients who were admitted with sporadic colorectal polyps and underwent polypectomy in endoscopy department during 2004-2008. Result: IHC results were abnormal in 6.8% cases for MLH1, in 4.5% cases for MSH2, in 3% for MSH6, and in 4.8% for PMS2. In all cases with abnormal PMS2, MLH1 was also reported as abnormal. Same results were reported for abnormal MSH2, which is accompanied with abnormal MSH6 in all cases (P values < 0.001. There is no significant difference between IHC staining results, gender, dysplasia grade, adenomatous type, and invasion. On the other hand, there was significant difference between IHC staining results, polyp location, and mean age of patients. The same significant difference was between adenomatous polyps and serrated adenoma polyps by MLH1 and PMS2 (P values < 0.05. Conclusion: According to our findings, maybe MMR dysfunction is the cause of sporadic colorectal polyps in younger age and its increasing risk of dysplasia progression and malignancy progression is only in serrated adenoma. Sporadic polyps in left colon had a higher risk to progress to malignancies, and abnormal IHC staining for MLH1 and PMS2 in serrated polyps is much more than in other adenomatous polyps.

The role of message framing in promoting MMR vaccination: evidence of a loss-frame advantage.

Science.gov (United States)

Abhyankar, Purva; O'Connor, Daryl B; Lawton, Rebecca

2008-01-01

This study examined the effects of message framing on intentions to obtain the measles, mumps and rubella (MMR) vaccine for one's child and investigated whether Theory of Planned Behaviour (TPB) and perceived outcome efficacy variables mediate and/or moderate message framing effects. One hundred and forty women read either a loss-framed or gain-framed message and then completed measures assessing their intentions to obtain the MMR vaccine for their child, and TPB and outcome efficacy variables. Exposure to the loss frame increased intentions to obtain the MMR vaccine and influenced perceptions of outcome efficacy. This suggests that outcome efficacy, but not other TPB variables may mediate framing effects within the context of MMR vaccination. Message frame, in addition to TPB variables, significantly predicted unique variance in behavioural intentions. These findings are discussed within the context of Prospect Theory, perceived risk and prevention/detection behaviours.

DNA repair: Dynamic defenders against cancer and aging

Energy Technology Data Exchange (ETDEWEB)

Fuss, Jill O.; Cooper, Priscilla K.

2006-04-01

(UV) component of sunlight. NER can be divided into two classes based on where the repair occurs. NER occurring in DNA that is not undergoing transcription (i.e., most of the genome) is called global genome repair (GGR or GGNER), while NER taking place in the transcribed strand of active genes is called transcription-coupled repair (TCR or TC-NER). We will explore NER in more detail below. Mismatch repair (MMR) is another type of excision repair that specifically removes mispaired bases resulting from replication errors. DNA damage can also result in breaks in the DNA backbone, in one or both strands. Single-strand breaks (SSBs) are efficiently repaired by a mechanism that shares common features with the later steps in BER. Double-strand breaks (DSBs) are especially devastating since by definition there is no intact complementary strand to serve as a template for repair, and even one unrepaired DSB can be lethal [3]. In cells that have replicated their DNA prior to cell division, the missing information can be supplied by the duplicate copy, or sister chromatid, and DSBs in these cells are faithfully repaired by homologous recombination involving the exchange of strands of DNA between the two copies. However, most cells in the body are non-dividing, and in these cells the major mechanism for repairing DSBs is by non-homologous end joining (NHEJ), which as the name implies involves joining two broken DNA ends together without a requirement for homologous sequence and which therefore has a high potential for loss of genetic information.

Germline truncating-mutations in BRCA1 and MSH6 in a patient with early onset endometrial cancer

International Nuclear Information System (INIS)

Kast, Karin; Schackert, Hans K; Neuhann, Teresa M; Görgens, Heike; Becker, Kerstin; Keller, Katja; Klink, Barbara; Aust, Daniela; Distler, Wolfgang; Schröck, Evelin

2012-01-01

Hereditary Breast and Ovarian Cancer Syndrome (HBOCS) and Hereditary Non-Polyposis Colorectal Cancer Syndrome (HNPCC, Lynch Syndrome) are two tumor predisposition syndromes responsible for the majority of hereditary breast and colorectal cancers. Carriers of both germline mutations in breast cancer genes BRCA1 or BRCA2 and in mismatch repair (MMR) genes MLH1, MSH2, MSH6 or PMS2 are very rare. We identified germline mutations in BRCA1 and in MSH6 in a patient with increased risk for HBOC diagnosed with endometrial cancer at the age of 46 years. Although carriers of mutations in both MMR and BRCA genes are rare in Caucasian populations and anamnestical and histopathological findings may guide clinicians to identify these families, both syndromes can only be diagnosed through a complete gene analysis of the respective genes

Germline truncating-mutations in BRCA1 and MSH6 in a patient with early onset endometrial cancer

Energy Technology Data Exchange (ETDEWEB)

Kast, Karin [Department of Gynecology and Obstetrics, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden (Germany); Schackert, Hans K [Department of Surgical Research, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden (Germany); Neuhann, Teresa M [Institute for Clinical Genetics, Technische Universität Dresden, Dresden (Germany); Medical Genetic Center, Munich (Germany); Görgens, Heike [Department of Surgical Research, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden (Germany); Becker, Kerstin [Institute for Clinical Genetics, Technische Universität Dresden, Dresden (Germany); Keller, Katja [Department of Gynecology and Obstetrics, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden (Germany); Klink, Barbara [Institute for Clinical Genetics, Technische Universität Dresden, Dresden (Germany); Aust, Daniela [Institute of Pathology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden (Germany); Distler, Wolfgang [Department of Gynecology and Obstetrics, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden (Germany); Schröck, Evelin [Institute for Clinical Genetics, Technische Universität Dresden, Dresden (Germany)

2012-11-20

Hereditary Breast and Ovarian Cancer Syndrome (HBOCS) and Hereditary Non-Polyposis Colorectal Cancer Syndrome (HNPCC, Lynch Syndrome) are two tumor predisposition syndromes responsible for the majority of hereditary breast and colorectal cancers. Carriers of both germline mutations in breast cancer genes BRCA1 or BRCA2 and in mismatch repair (MMR) genes MLH1, MSH2, MSH6 or PMS2 are very rare. We identified germline mutations in BRCA1 and in MSH6 in a patient with increased risk for HBOC diagnosed with endometrial cancer at the age of 46 years. Although carriers of mutations in both MMR and BRCA genes are rare in Caucasian populations and anamnestical and histopathological findings may guide clinicians to identify these families, both syndromes can only be diagnosed through a complete gene analysis of the respective genes.

Germline truncating-mutations in BRCA1 and MSH6 in a patient with early onset endometrial cancer.

Science.gov (United States)

Kast, Karin; Neuhann, Teresa M; Görgens, Heike; Becker, Kerstin; Keller, Katja; Klink, Barbara; Aust, Daniela; Distler, Wolfgang; Schröck, Evelin; Schackert, Hans K

2012-11-20

Hereditary Breast and Ovarian Cancer Syndrome (HBOCS) and Hereditary Non-Polyposis Colorectal Cancer Syndrome (HNPCC, Lynch Syndrome) are two tumor predisposition syndromes responsible for the majority of hereditary breast and colorectal cancers. Carriers of both germline mutations in breast cancer genes BRCA1 or BRCA2 and in mismatch repair (MMR) genes MLH1, MSH2, MSH6 or PMS2 are very rare. We identified germline mutations in BRCA1 and in MSH6 in a patient with increased risk for HBOC diagnosed with endometrial cancer at the age of 46 years. Although carriers of mutations in both MMR and BRCA genes are rare in Caucasian populations and anamnestical and histopathological findings may guide clinicians to identify these families, both syndromes can only be diagnosed through a complete gene analysis of the respective genes.

Selective tumor cell death induced by irradiated riboflavin through recognizing DNA G-T mismatch.

Science.gov (United States)

Yuan, Yi; Zhao, Yongyun; Chen, Lianqi; Wu, Jiasi; Chen, Gangyi; Li, Sheng; Zou, Jiawei; Chen, Rong; Wang, Jian; Jiang, Fan; Tang, Zhuo

2017-09-06

Riboflavin (vitamin B2) has been thought to be a promising antitumoral agent in photodynamic therapy, though the further application of the method was limited by the unclear molecular mechanism. Our work reveals that riboflavin was able to recognize G-T mismatch specifically and induce single-strand breaks in duplex DNA targets efficiently under irradiation. In the presence of riboflavin, the photo-irradiation could induce the death of tumor cells that are defective in mismatch repair system selectively, highlighting the G-T mismatch as potential drug target for tumor cells. Moreover, riboflavin is a promising leading compound for further drug design due to its inherent specific recognition of the G-T mismatch. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

MLH1 function is context dependent in colorectal cancers.

Science.gov (United States)

Jackson, Thomas; Ahmed, Mohamed A H; Seth, Rashmi; Jackson, Darryl; Ilyas, Mohammad

2011-02-01

Loss of mismatch repair (MMR) function in sporadic colorectal cancer occurs most commonly because of inactivation of MLH1, and it causes an increase in mutation rate. However, it is uncertain whether loss of MMR alters any other cellular function. The aim of this study was to investigate the role of MMR in regulating cell numbers and apoptosis. MLH1 protein levels were manipulated by (a) cloning and forcibly expressing MLH1 in HCT116 (a cell line with MLH1 mutation) and RKO (a cell line with MLH1 silencing), and (b) knockdown of MLH1 in SW480 (a cell line with normal MMR function). Cell number and apoptotic bodies were measured in standard and 'high stress' (ie, after staurosporine exposure) conditions. Restoration of MLH1 function in HCT116 and RKO resulted in increased cell number (pculture conditions. However, on induction of apoptotic stress, restoration of MLH1 resulted in reduced cell numbers (pcontext dependent: in 'low stress' conditions it may act to inhibit apoptosis, while in 'high stress' conditions it may induce apoptosis. However, within the context of chromosomal instability, the effect of MLH1 on cell numbers is limited.

Apoptotic function of human PMS2 compromised by the nonsynonymous single-nucleotide polymorphic variant R20Q.

Science.gov (United States)

Marinovic-Terzic, Ivana; Yoshioka-Yamashita, Atsuko; Shimodaira, Hideki; Avdievich, Elena; Hunton, Irina C; Kolodner, Richard D; Edelmann, Winfried; Wang, Jean Y J

2008-09-16

Mismatch repair (MMR) corrects replication errors during DNA synthesis. The mammalian MMR proteins also activate cell cycle checkpoints and apoptosis in response to persistent DNA damage. MMR-deficient cells are resistant to cisplatin, a DNA cross-linking agent used in chemotherapy, because of impaired activation of apoptotic pathways. It is shown that postmeiotic segregation 2 (PMS2), an MMR protein, is required for cisplatin-induced activation of p73, a member of the p53 family of transcription factors with proapoptotic activity. The human PMS2 is highly polymorphic, with at least 12 known nonsynonymous codon changes identified. We show here that the PMS2(R20Q) variant is defective in activating p73-dependent apoptotic response to cisplatin. When expressed in Pms2-deficient mouse fibroblasts, human PMS2(R20Q) but not PMS2 interfered with the apoptotic response to cisplatin. Correspondingly, PMS2 but not PMS2(R20Q) enhanced the cytotoxic effect of cisplatin measured by clonogenic survival. Because PMS2(R20Q) lacks proapoptotic activity, this polymorphic allele may modulate tumor responses to cisplatin among cancer patients.

Attitudinal and demographic predictors of measles-mumps-rubella vaccine (MMR uptake during the UK catch-up campaign 2008-09: cross-sectional survey.

Directory of Open Access Journals (Sweden)

Katrina Brown

Full Text Available BACKGROUND AND OBJECTIVE: Continued suboptimal measles-mumps-rubella (MMR vaccine uptake has re-established measles epidemic risk, prompting a UK catch-up campaign in 2008-09 for children who missed MMR doses at scheduled age. Predictors of vaccine uptake during catch-ups are poorly understood, however evidence from routine schedule uptake suggests demographics and attitudes may be central. This work explored this hypothesis using a robust evidence-based measure. DESIGN: Cross-sectional self-administered questionnaire with objective behavioural outcome. SETTING AND PARTICIPANTS: 365 UK parents, whose children were aged 5-18 years and had received <2 MMR doses before the 2008-09 UK catch-up started. MAIN OUTCOME MEASURES: Parents' attitudes and demographics, parent-reported receipt of invitation to receive catch-up MMR dose(s, and catch-up MMR uptake according to child's medical record (receipt of MMR doses during year 1 of the catch-up. RESULTS: Perceived social desirability/benefit of MMR uptake (OR = 1.76, 95% CI = 1.09-2.87 and younger child age (OR = 0.78, 95% CI = 0.68-0.89 were the only independent predictors of catch-up MMR uptake in the sample overall. Uptake predictors differed by whether the child had received 0 MMR doses or 1 MMR dose before the catch-up. Receipt of catch-up invitation predicted uptake only in the 0 dose group (OR = 3.45, 95% CI = 1.18-10.05, whilst perceived social desirability/benefit of MMR uptake predicted uptake only in the 1 dose group (OR = 9.61, 95% CI = 2.57-35.97. Attitudes and demographics explained only 28% of MMR uptake in the 0 dose group compared with 61% in the 1 dose group. CONCLUSIONS: Catch-up MMR invitations may effectively move children from 0 to 1 MMR doses (unimmunised to partially immunised, whilst attitudinal interventions highlighting social benefits of MMR may effectively move children from 1 to 2 MMR doses (partially to fully immunised. Older children may be

mlh3 mutations in baker's yeast alter meiotic recombination outcomes by increasing noncrossover events genome-wide.

Directory of Open Access Journals (Sweden)

Najla Al-Sweel

2017-08-01

Full Text Available Mlh1-Mlh3 is an endonuclease hypothesized to act in meiosis to resolve double Holliday junctions into crossovers. It also plays a minor role in eukaryotic DNA mismatch repair (MMR. To understand how Mlh1-Mlh3 functions in both meiosis and MMR, we analyzed in baker's yeast 60 new mlh3 alleles. Five alleles specifically disrupted MMR, whereas one (mlh3-32 specifically disrupted meiotic crossing over. Mlh1-mlh3 representatives for each class were purified and characterized. Both Mlh1-mlh3-32 (MMR+, crossover- and Mlh1-mlh3-45 (MMR-, crossover+ displayed wild-type endonuclease activities in vitro. Msh2-Msh3, an MSH complex that acts with Mlh1-Mlh3 in MMR, stimulated the endonuclease activity of Mlh1-mlh3-32 but not Mlh1-mlh3-45, suggesting that Mlh1-mlh3-45 is defective in MSH interactions. Whole genome recombination maps were constructed for wild-type and MMR+ crossover-, MMR- crossover+, endonuclease defective and null mlh3 mutants in an S288c/YJM789 hybrid background. Compared to wild-type, all of the mlh3 mutants showed increases in the number of noncrossover events, consistent with recombination intermediates being resolved through alternative recombination pathways. Our observations provide a structure-function map for Mlh3 that reveals the importance of protein-protein interactions in regulating Mlh1-Mlh3's enzymatic activity. They also illustrate how defective meiotic components can alter the fate of meiotic recombination intermediates, providing new insights for how meiotic recombination pathways are regulated.

Single-Nucleotide Polymorphisms of the MSH2 and MLH1 Genes, Potential Molecular Markers for Susceptibility to the Development of Basal Cell Carcinoma in the Brazilian Population.

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da Silva Calixto, Poliane; Lopes, Otávio Sérgio; Dos Santos Maia, Mayara; Herrero, Sylvia Satomi Takeno; Longui, Carlos Alberto; Melo, Cynthia Germoglio Farias; de Carvalho Filho, Ivan Rodrigues; Soares, Leonardo Ferreira; de Medeiros, Arnaldo Correia; Delatorre, Plínio; Khayat, André Salim; Burbano, Rommel Rodriguez; Lima, Eleonidas Moura

2018-07-01

Basal cell carcinoma - BCC is considered a multifactorial neoplasm involving genetic, epigenetic and environmental factors. Where UVB radiation is considered the main physical agent involved in BCC carcinogenesis. The Brazil and state of Paraíba are exposed to high levels of UVB rays. The mismatch repair - MMR is important DNA repair mechanisms to maintain replication fidelity. Therefore, single nucleotide polymorphisms (SNPs) in genes encoding proteins involved in MMR may be potential molecular markers of susceptibility to BCC. The objective of this study was to evaluate and describe for the first time the SNPs rs560246973, rs2303425 and rs565410865 and risk of developing BCC. The present study analyzed 100 samples of paraffin-embedded tissue from patients with histopathological diagnosis of BCC and 100 control samples. The results were obtained by genotyping method, Dideoxy Unique Allele Specific - PCR (DSASP). The SNPs rs2303425 were not associated with Basal Cell Carcinoma. However, the SNPs rs560246973 and rs565410865 was shown to be associated with the development of BCC when compared to control samples (P molecular markers for BCC.

A novel heterozygous germline deletion in MSH2 gene in a five generation Chinese family with Lynch syndrome

OpenAIRE

Wu, Bin; Ji, Wuyang; Liang, Shengran; Ling, Chao; You, Yan; Xu, Lai; Zhong, Min-Er; Xiao, Yi; Qiu, Hui-Zhong; Lu, Jun-Yang; Banerjee, Santasree

2017-01-01

Lynch syndrome (LS) is one of the most common familial forms of colorectal cancer predisposing syndrome with an autosomal dominant mode of inheritance. LS is caused by the germline mutations in DNA mismatch repair (MMR) genes including MSH2, MLH1, MSH6 and PMS2. Clinically, LS is characterized by high incidence of early-onset colorectal cancer as well as endometrial, small intestinal and urinary tract cancers, usually occur in the third to fourth decade of the life. Here we describe a five ge...

Alkylation damage in DNA and RNA--repair mechanisms and medical significance

DEFF Research Database (Denmark)

Drabløs, Finn; Feyzi, Emadoldin; Aas, Per Arne

2004-01-01

Alkylation lesions in DNA and RNA result from endogenous compounds, environmental agents and alkylating drugs. Simple methylating agents, e.g. methylnitrosourea, tobacco-specific nitrosamines and drugs like temozolomide or streptozotocin, form adducts at N- and O-atoms in DNA bases. These lesions...... are mainly repaired by direct base repair, base excision repair, and to some extent by nucleotide excision repair (NER). The identified carcinogenicity of O(6)-methylguanine (O(6)-meG) is largely caused by its miscoding properties. Mutations from this lesion are prevented by O(6)-alkylG-DNA alkyltransferase......, inactivation of the MMR system in an AGT-defective background causes resistance to the killing effects of O(6)-alkylating agents, but not to the mutagenic effect. Bifunctional alkylating agents, such as chlorambucil or carmustine (BCNU), are commonly used anti-cancer drugs. DNA lesions caused by these agents...

DNA repair in Haemophilus influenzae: isolation and characterization of an ultraviolet sensitive mutator mutant

International Nuclear Information System (INIS)

Walter, R.B.

1985-01-01

DNA repair in Haemophilus influenzae appears to be quite different from that seen in Escherichia coli in that H. influenzae shows neither SOS nor adaptation phenomena. Repair of DNA lesions in H. influenzae has been seen to occur via recombinational, excision, and mismatch repair pathways acting independently of one another. The author has isolated an ultraviolet (UV)-sensitive mutator mutant (mutB1) of H. influenzae Rd which shows deficiencies in both recombinational and mismatch repair pathways. This mutant is sensitive to a variety of DNA damaging agents as well as being hypermutable by alkylating agents and base analogues. MutB1 cells do not show post-UV DNA breakdown but do begin excision after UV irradiation. Genetic transformation with UV-irradiated DNA on mut B1 recipients shows that high (HE) and low (LE) efficiency markers are transformed at a ratio of 1.0 as in the mismatch repair deficient hex 1 mutant; however, kinetics of UV-inactivation experiments indicate that HE markers are sensitized and act as LE markers do on wild type recipients. Thus, the mutB gene product appears to play a role in both DNA repair and genetic transformation. A model is outlined which presents a role for a DNA helicase in both DNA repair and genetic transformation of H. influenzae

Radiotherapy Results of Midline Malignant Reticulosis (MMR)

International Nuclear Information System (INIS)

Yun, Sang Mo; Kim, Jae Cheol

1996-01-01

Purpose : This study was performed to evaluate survival, failure patterns, and prognositc factors of MMR patients after radiation therapy. We also discussed the need for chemotherapy. Materials and Methods : A retrospective analysis was done for 23 patients with MMR who were treated with radiation therapy form June 1985 to November 1992. There were 19 male and 4 female patients. The patients age ranged from 17 to 71 years(median 39 years). Systemic symptoms including fever, weight loss, or malaise were found in 30% of the patients. He nasal cavity was most frequently involved. No patients had nodal involvement at diagnosis. There were 2 patients with distant metastasis at presentation. Radiation therapy was delivered five times a week, 1.8 Gy daily, total 45∼54 Gy(median 50.4 Gy) using 6 MV X-ray. No patients received chemotherapy as initial treatment. Results : Overall 5-year and 10-year survival rates were 52.4% and 44.1%, respectively. Seventy percent(12/17) of the patients achieved complete response to radiotherapy., and 29.4%(5/17) achieved partial response. The patients with complete response showed a better 5-year survival rate than those with partial response (66.9% vs. 20%, p-0.004). Symptom duration before diagnosis, the presence of systemic symptom, ad the number of primary sites had no influence on survival. The patterns of failure were as flows: local failure(1), failure in adjacent site(1), local and distant failure(1), distant metastasis(2), and conversion to malignant lymphoma(1). W could not find factors associated with the patterns of failure. Conclusion : The most important factor associated with survival was the response to radiotherapy. Seventeen percent of the patients had distant metastasis, and the salvage after distant metastasis was not successful. However, about 50% of the patients could achieve long-term survival with local radiation therapy alone. Therefore, chemotherapy of MMR should be done after a prospective randomized study for

Ovarian cancer at young age: the contribution of mismatch-repair defects in a population-based series of epithelial ovarian

DEFF Research Database (Denmark)

Domanska, K; Malander, S; Måsbäck, A

2007-01-01

age is a hallmark of heredity, and ovarian cancers associated with HNPCC have been demonstrated to develop at a particularly early age. We used the Swedish Cancer Registry to identify a population-based series of 98 invasive epithelial ovarian cancers that developed before 40 years. Mucinous......At least one of ten patients with ovarian cancer is estimated to develop their tumor because of heredity with the breast and ovarian cancer syndrome due to mutations in the BRCA1 and BRCA2 genes and hereditary nonpolyposis colorectal cancer (HNPCC) being the major genetic causes. Cancer at young...... and endometrioid cancers were overrepresented and were diagnosed in 27% and 16% of the tumors, respectively. Immunostaining using antibodies against MLH1, PMS2, MSH2, and MSH6 was used to assess the mismatch-repair status and revealed loss of expression of MLH1/PMS2 in two cases, loss of MSH2/MSH6 in one case...

Persistence of DNA adducts, hypermutation and acquisition of cellular resistance to alkylating agents in glioblastoma.

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Head, R J; Fay, M F; Cosgrove, L; Y C Fung, K; Rundle-Thiele, D; Martin, J H

2017-12-02

Glioblastoma is a lethal form of brain tumour usually treated by surgical resection followed by radiotherapy and an alkylating chemotherapeutic agent. Key to the success of this multimodal approach is maintaining apoptotic sensitivity of tumour cells to the alkylating agent. This initial treatment likely establishes conditions contributing to development of drug resistance as alkylating agents form the O 6 -methylguanine adduct. This activates the mismatch repair (MMR) process inducing apoptosis and mutagenesis. This review describes key juxtaposed drivers in the balance between alkylation induced mutagenesis and apoptosis. Mutations in MMR genes are the probable drivers for alkylation based drug resistance. Critical to this interaction are the dose-response and temporal interactions between adduct formation and MMR mutations. The precision in dose interval, dose-responses and temporal relationships dictate a role for alkylating agents in either promoting experimental tumour formation or inducing tumour cell death with chemotherapy. Importantly, this resultant loss of chemotherapeutic selective pressure provides opportunity to explore novel therapeutics and appropriate combinations to minimise alkylation based drug resistance and tumour relapse.

The mutational profile and infiltration pattern of murine MLH1-/- tumors: concurrences, disparities and cell line establishment for functional analysis.

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Maletzki, Claudia; Beyrich, Franziska; Hühns, Maja; Klar, Ernst; Linnebacher, Michael

2016-08-16

Mice lines homozygous negative for one of the four DNA mismatch repair (MMR) genes (MLH1, MSH2, PMS2, MSH6) were generated as models for MMR deficient (MMR-D) diseases. Clinically, hereditary forms of MMR-D include Lynch syndrome (characterized by a germline MMR gene defect) and constitutional MMR-D, the biallelic form. MMR-D knockout mice may be representative for both diseases. Here, we aimed at characterizing the MLH1-/- model focusing on tumor-immune microenvironment and identification of coding microsatellite mutations in lymphomas and gastrointestinal tumors (GIT).All tumors showed microsatellite instability (MSI) in non-coding mononucleotide markers. Mutational profiling of 26 coding loci in MSI+ GIT and lymphomas revealed instability in half of the microsatellites, two of them (Rfc3 and Rasal2) shared between both entities. MLH1-/- tumors of both entities displayed a similar phenotype (high CD71, FasL, PD-L1 and CTLA-4 expression). Additional immunofluorescence verified the tumors' natural immunosuppressive character (marked CD11b/CD200R infiltration). Vice versa, CD3+ T cells as well as immune checkpoints molecules were detectable, indicative for an active immune microenvironment. For functional analysis, a permanent cell line from an MLH1-/- GIT was established. The newly developed MLH1-/- A7450 cells exhibit stable in vitro growth, strong invasive potential and heterogeneous drug response. Moreover, four additional MSI target genes (Nktr1, C8a, Taf1b, and Lig4) not recognized in the primary were identified in this cell line.Summing up, molecular and immunological mechanisms of MLH1-/- driven carcinogenesis correlate well with clinical features of MMR-D. MLH1-/- knockout mice combine characteristics of Lynch syndrome and constitutional MMR-D, making them suitable models for preclinical research aiming at MMR-D related diseases.

Measles, Mumps, and Rubella (MMR) Vaccination: What Everyone Should Know

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... information, see State Vaccination Requirements . How Can Parents Pay For MMR Vaccine? Most health insurance plans cover ... Word file Microsoft Excel file Audio/Video file Apple Quicktime file RealPlayer file Text file Zip Archive ...

Predictive models for mutations in mismatch repair genes: implication for genetic counseling in developing countries

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Monteiro Santos Erika

2012-02-01

Full Text Available Abstract Background Lynch syndrome (LS is the most common form of inherited predisposition to colorectal cancer (CRC, accounting for 2-5% of all CRC. LS is an autosomal dominant disease characterized by mutations in the mismatch repair genes mutL homolog 1 (MLH1, mutS homolog 2 (MSH2, postmeiotic segregation increased 1 (PMS1, post-meiotic segregation increased 2 (PMS2 and mutS homolog 6 (MSH6. Mutation risk prediction models can be incorporated into clinical practice, facilitating the decision-making process and identifying individuals for molecular investigation. This is extremely important in countries with limited economic resources. This study aims to evaluate sensitivity and specificity of five predictive models for germline mutations in repair genes in a sample of individuals with suspected Lynch syndrome. Methods Blood samples from 88 patients were analyzed through sequencing MLH1, MSH2 and MSH6 genes. The probability of detecting a mutation was calculated using the PREMM, Barnetson, MMRpro, Wijnen and Myriad models. To evaluate the sensitivity and specificity of the models, receiver operating characteristic curves were constructed. Results Of the 88 patients included in this analysis, 31 mutations were identified: 16 were found in the MSH2 gene, 15 in the MLH1 gene and no pathogenic mutations were identified in the MSH6 gene. It was observed that the AUC for the PREMM (0.846, Barnetson (0.850, MMRpro (0.821 and Wijnen (0.807 models did not present significant statistical difference. The Myriad model presented lower AUC (0.704 than the four other models evaluated. Considering thresholds of ≥ 5%, the models sensitivity varied between 1 (Myriad and 0.87 (Wijnen and specificity ranged from 0 (Myriad to 0.38 (Barnetson. Conclusions The Barnetson, PREMM, MMRpro and Wijnen models present similar AUC. The AUC of the Myriad model is statistically inferior to the four other models.

Association between perfluoroalkyl substance exposure and asthma and allergic disease in children as modified by MMR vaccination

DEFF Research Database (Denmark)

Timmermann, Clara Amalie Gade; Budtz-Jørgensen, Esben; Jensen, Tina Kold

2017-01-01

Perfluoroalkyl substances (PFASs) are highly persistent chemicals that might be associated with asthma and allergy, but the associations remain unclear. Therefore, this study examined whether pre- and postnatal PFAS exposure was associated with childhood asthma and allergy. Measles, mumps......, and rubella (MMR) vaccination in early life may have a protective effect against asthma and allergy, and MMR vaccination is therefore taken into account when evaluating these associations. In a cohort of Faroese children whose mothers were recruited during pregnancy, serum concentrations of five PFASs...... with immunoglobulin E (IgE) (cord blood and at age 7 years) and asthma/allergic diseases (questionnaires at ages 5 and 13 years and skin prick test at age 13 years) was determined. A total of 559 children were included in the analyses. Interactions with MMR vaccination were evaluated. Among 22 MMR...

[Lack of association between MMR vaccination and the incidence of autism in children: a case-control study].

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Mrozek-Budzyn, Dorota; Kiełtyka, Agnieszka; Majewska, Renata

2009-01-01

The matched case-control study has been undertook to investigate whether measles, mumps, and rubella (MMR) vaccine may be casually associated with autism in children. Cases were children to 14-year old with diagnosis of core autism or atypical autism. Controls were matched on age, sex and general practice. The 96 cases and 192 controls were included. The study provides strong evidence against association of autism with both MMR and a single measles individual vaccine. Additionally children vaccinated with MMR, regardless of age of vaccination (to 18th, 24th and 36th month of life), had risk equal half of that of single measles vaccinated (for vaccinated to 18th month OR=0.41 95%PU: 0.20-0.85). Our findings confirm that MMR vaccination is not associated with an increased risk of autism in children.

DNA methylation polymorphism in a set of elite rice cultivars and its possible contribution to inter-cultivar differential gene expression.

Science.gov (United States)

Wang, Yongming; Lin, Xiuyun; Dong, Bo; Wang, Yingdian; Liu, Bao

2004-01-01

RAPD (randomly amplified polymorphic DNA) and ISSR (inter-simple sequence repeat) fingerprinting on HpaII/MspI-digested genomic DNA of nine elite japonica rice cultivars implies inter-cultivar DNA methylation polymorphism. Using both DNA fragments isolated from RAPD or ISSR gels and selected low-copy sequences as probes, methylation-sensitive Southern blot analysis confirms the existence of extensive DNA methylation polymorphism in both genes and DNA repeats among the rice cultivars. The cultivar-specific methylation patterns are stably maintained, and can be used as reliable molecular markers. Transcriptional analysis of four selected sequences (RdRP, AC9, HSP90 and MMR) on leaves and roots from normal and 5-azacytidine-treated seedlings of three representative cultivars shows an association between the transcriptional activity of one of the genes, the mismatch repair (MMR) gene, and its CG methylation patterns.

Germline truncating-mutations in BRCA1 and MSH6 in a patient with early onset endometrial cancer

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Kast Karin

2012-11-01

Full Text Available Abstract Background Hereditary Breast and Ovarian Cancer Syndrome (HBOCS and Hereditary Non-Polyposis Colorectal Cancer Syndrome (HNPCC, Lynch Syndrome are two tumor predisposition syndromes responsible for the majority of hereditary breast and colorectal cancers. Carriers of both germline mutations in breast cancer genes BRCA1 or BRCA2 and in mismatch repair (MMR genes MLH1, MSH2, MSH6 or PMS2 are very rare. Case presentation We identified germline mutations in BRCA1 and in MSH6 in a patient with increased risk for HBOC diagnosed with endometrial cancer at the age of 46 years. Conclusions Although carriers of mutations in both MMR and BRCA genes are rare in Caucasian populations and anamnestical and histopathological findings may guide clinicians to identify these families, both syndromes can only be diagnosed through a complete gene analysis of the respective genes.

Genetic screens to identify pathogenic gene variants in the common cancer predisposition Lynch syndrome

DEFF Research Database (Denmark)

Drost, Mark; Lützen, Anne; van Hees, Sandrine

2013-01-01

In many individuals suspected of the common cancer predisposition Lynch syndrome, variants of unclear significance (VUS), rather than an obviously pathogenic mutations, are identified in one of the DNA mismatch repair (MMR) genes. The uncertainty of whether such VUS inactivate MMR, and therefore...... function. When a residue identified as mutated in an individual suspected of Lynch syndrome is listed as critical in such a reverse diagnosis catalog, there is a high probability that the corresponding human VUS is pathogenic. To investigate the applicability of this approach, we have generated....... Nearly half of these critical residues match with VUS previously identified in individuals suspected of Lynch syndrome. This aids in the assignment of pathogenicity to these human VUS and validates the approach described here as a diagnostic tool. In a wider perspective, this work provides a model...

Phosphorylation-dependent signaling controls degradation of DNA mismatch repair protein PMS2.

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Hinrichsen, Inga; Weßbecher, Isabel M; Huhn, Meik; Passmann, Sandra; Zeuzem, Stefan; Plotz, Guido; Biondi, Ricardo M; Brieger, Angela

2017-12-01

MutLα, a heterodimer consisting of MLH1 and PMS2, plays an important role in DNA mismatch repair and has been shown to be additionally involved in several other important cellular mechanisms. Previous work indicated that AKT could modulate PMS2 stability by phosphorylation. Still, the mechanisms of regulation of MutLα remain unclear. The stability of MutLα subunits was investigated by transiently overexpression of wild type and mutant forms of MLH1 and PMS2 using immunoblotting for measuring the protein levels after treatment. We found that treatment with the cell-permeable serine/threonine phosphatase inhibitor, Calyculin, leads to degradation of PMS2 when MLH1 or its C-terminal domain is missing or if amino acids of MLH1 essential for PMS2 interaction are mutated. In addition, we discovered that the C-terminal tail of PMS2 is relevant for this Calyculin-dependent degradation. A direct involvement of AKT, which was previously described to be responsible for PMS2 degradation, could not be detected. The multi-kinase inhibitor Sorafenib, in contrast, was able to avoid the degradation of PMS2 which postulates that cellular phosphorylation is involved in this process. Together, we show that pharmacologically induced phosphorylation by Calyculin can induce the selective proteasome-dependent degradation of PMS2 but not of MLH1 and that the PMS2 degradation could be blocked by Sorafenib treatment. Curiously, the C-terminal Lynch Syndrome-variants MLH1 L749P and MLH1 Y750X make PMS2 prone to Calyculin induced degradation. Therefore, we conclude that the specific degradation of PMS2 may represent a new mechanism to regulate MutLα. © 2017 Wiley Periodicals, Inc.

Different roles of eukaryotic MutS and MutL complexes in repair of small insertion and deletion loops in yeast.

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Nina V Romanova

2013-10-01

Full Text Available DNA mismatch repair greatly increases genome fidelity by recognizing and removing replication errors. In order to understand how this fidelity is maintained, it is important to uncover the relative specificities of the different components of mismatch repair. There are two major mispair recognition complexes in eukaryotes that are homologues of bacterial MutS proteins, MutSα and MutSβ, with MutSα recognizing base-base mismatches and small loop mispairs and MutSβ recognizing larger loop mispairs. Upon recognition of a mispair, the MutS complexes then interact with homologues of the bacterial MutL protein. Loops formed on the primer strand during replication lead to insertion mutations, whereas loops on the template strand lead to deletions. We show here in yeast, using oligonucleotide transformation, that MutSα has a strong bias toward repair of insertion loops, while MutSβ has an even stronger bias toward repair of deletion loops. Our results suggest that this bias in repair is due to the different interactions of the MutS complexes with the MutL complexes. Two mutants of MutLα, pms1-G882E and pms1-H888R, repair deletion mispairs but not insertion mispairs. Moreover, we find that a different MutL complex, MutLγ, is extremely important, but not sufficient, for deletion repair in the presence of either MutLα mutation. MutSβ is present in many eukaryotic organisms, but not in prokaryotes. We suggest that the biased repair of deletion mispairs may reflect a critical eukaryotic function of MutSβ in mismatch repair.

Evolution and adaptation in Pseudomonas aeruginosa biofilms driven by mismatch repair system-deficient mutators.

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Adela M Luján

Full Text Available Pseudomonas aeruginosa is an important opportunistic pathogen causing chronic airway infections, especially in cystic fibrosis (CF patients. The majority of the CF patients acquire P. aeruginosa during early childhood, and most of them develop chronic infections resulting in severe lung disease, which are rarely eradicated despite intensive antibiotic therapy. Current knowledge indicates that three major adaptive strategies, biofilm development, phenotypic diversification, and mutator phenotypes [driven by a defective mismatch repair system (MRS], play important roles in P. aeruginosa chronic infections, but the relationship between these strategies is still poorly understood. We have used the flow-cell biofilm model system to investigate the impact of the mutS associated mutator phenotype on development, dynamics, diversification and adaptation of P. aeruginosa biofilms. Through competition experiments we demonstrate for the first time that P. aeruginosa MRS-deficient mutators had enhanced adaptability over wild-type strains when grown in structured biofilms but not as planktonic cells. This advantage was associated with enhanced micro-colony development and increased rates of phenotypic diversification, evidenced by biofilm architecture features and by a wider range and proportion of morphotypic colony variants, respectively. Additionally, morphotypic variants generated in mutator biofilms showed increased competitiveness, providing further evidence for mutator-driven adaptive evolution in the biofilm mode of growth. This work helps to understand the basis for the specific high proportion and role of mutators in chronic infections, where P. aeruginosa develops in biofilm communities.

Tolerance of DNA Mismatches in Dmc1 Recombinase-mediated DNA Strand Exchange*

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Borgogno, María V.; Monti, Mariela R.; Zhao, Weixing; Sung, Patrick; Argaraña, Carlos E.; Pezza, Roberto J.

2016-01-01

Recombination between homologous chromosomes is required for the faithful meiotic segregation of chromosomes and leads to the generation of genetic diversity. The conserved meiosis-specific Dmc1 recombinase catalyzes homologous recombination triggered by DNA double strand breaks through the exchange of parental DNA sequences. Although providing an efficient rate of DNA strand exchange between polymorphic alleles, Dmc1 must also guard against recombination between divergent sequences. How DNA mismatches affect Dmc1-mediated DNA strand exchange is not understood. We have used fluorescence resonance energy transfer to study the mechanism of Dmc1-mediated strand exchange between DNA oligonucleotides with different degrees of heterology. The efficiency of strand exchange is highly sensitive to the location, type, and distribution of mismatches. Mismatches near the 3′ end of the initiating DNA strand have a small effect, whereas most mismatches near the 5′ end impede strand exchange dramatically. The Hop2-Mnd1 protein complex stimulates Dmc1-catalyzed strand exchange on homologous DNA or containing a single mismatch. We observed that Dmc1 can reject divergent DNA sequences while bypassing a few mismatches in the DNA sequence. Our findings have important implications in understanding meiotic recombination. First, Dmc1 acts as an initial barrier for heterologous recombination, with the mismatch repair system providing a second level of proofreading, to ensure that ectopic sequences are not recombined. Second, Dmc1 stepping over infrequent mismatches is likely critical for allowing recombination between the polymorphic sequences of homologous chromosomes, thus contributing to gene conversion and genetic diversity. PMID:26709229

Knowledge, attitudes and opinions towards measles and the MMR vaccine across two NSW cohorts.

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Brieger, Daniel; Edwards, Matthew; Mudgil, Poonam; Whitehall, John

2017-12-01

Although the number of national measles cases has greatly decreased since 1980s, there has been resurgence in disease incidence in recent years. While parental knowledge and attitudes toward both disease and vaccinations are known to influence vaccine uptake, the contribution of these factors toward vaccination rates in NSW populations has not been studied. The aim of this study was to investigate the knowledge and opinions on measles and MMR vaccine in NSW Central and North Coast regions. Parents (n=201) of children <12 years were surveyed with a purpose design survey at public beaches at the Central Coast and community markets at the North Coast. Eight per cent of respondents reported not immunising their child with MMR vaccine. Most respondents recognised that measles is a highly contagious disease. Non-immunisers were found to be older, had a lower perceived severity of measles, were less likely to agree with the efficacy and safety of the vaccine, and were more likely to have encountered someone who had suffered side-effects of the vaccine. There is considerable concern over safety of MMR vaccine among non-immunisers. Implications for public health: Improving confidence in MMR vaccine should be a target of future public health interventions. © 2017 The Authors.

The effect of S-substitution at the O6-guanine site on the structure and dynamics of a DNA oligomer containing a G:T mismatch.

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Elaine Ann Moore

Full Text Available The effect of S-substitution on the O6 guanine site of a 13-mer DNA duplex containing a G:T mismatch is studied using molecular dynamics. The structure, dynamic evolution and hydration of the S-substituted duplex are compared with those of a normal duplex, a duplex with S-substitution on guanine, but no mismatch and a duplex with just a G:T mismatch. The S-substituted mismatch leads to cell death rather than repair. One suggestion is that the G:T mismatch recognition protein recognises the S-substituted mismatch (GS:T as G:T. This leads to a cycle of futile repair ending in DNA breakage and cell death. We find that some structural features of the helix are similar for the duplex with the G:T mismatch and that with the S-substituted mismatch, but differ from the normal duplex, notably the helical twist. These differences arise from the change in the hydrogen-bonding pattern of the base pair. However a marked feature of the S-substituted G:T mismatch duplex is a very large opening. This showed considerable variability. It is suggested that this enlarged opening would lend support to an alternative model of cell death in which the mismatch protein attaches to thioguanine and activates downstream damage-response pathways. Attack on the sulphur by reactive oxygen species, also leading to cell death, would also be aided by the large, variable opening.

Human longevity and variation in DNA damage response and repair

DEFF Research Database (Denmark)

Debrabant, Birgit; Soerensen, Mette; Flachsbart, Friederike

2014-01-01

others. Data were applied on 592 SNPs from 77 genes involved in nine sub-processes: DNA-damage response, base excision repair (BER), nucleotide excision repair, mismatch repair, non-homologous end-joining, homologous recombinational repair (HRR), RecQ helicase activities (RECQ), telomere functioning...... in genotyping procedures and investigated SNPs, potentially inducing differences in the coverage of gene regions. Specifically, five genes were not covered at all in the German data. Therefore, investigations in additional study populations are needed before final conclusion can be drawn....

Pms2 suppresses large expansions of the (GAA·TTCn sequence in neuronal tissues.

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Rebecka L Bourn

Full Text Available Expanded trinucleotide repeat sequences are the cause of several inherited neurodegenerative diseases. Disease pathogenesis is correlated with several features of somatic instability of these sequences, including further large expansions in postmitotic tissues. The presence of somatic expansions in postmitotic tissues is consistent with DNA repair being a major determinant of somatic instability. Indeed, proteins in the mismatch repair (MMR pathway are required for instability of the expanded (CAG·CTG(n sequence, likely via recognition of intrastrand hairpins by MutSβ. It is not clear if or how MMR would affect instability of disease-causing expanded trinucleotide repeat sequences that adopt secondary structures other than hairpins, such as the triplex/R-loop forming (GAA·TTC(n sequence that causes Friedreich ataxia. We analyzed somatic instability in transgenic mice that carry an expanded (GAA·TTC(n sequence in the context of the human FXN locus and lack the individual MMR proteins Msh2, Msh6 or Pms2. The absence of Msh2 or Msh6 resulted in a dramatic reduction in somatic mutations, indicating that mammalian MMR promotes instability of the (GAA·TTC(n sequence via MutSα. The absence of Pms2 resulted in increased accumulation of large expansions in the nervous system (cerebellum, cerebrum, and dorsal root ganglia but not in non-neuronal tissues (heart and kidney, without affecting the prevalence of contractions. Pms2 suppressed large expansions specifically in tissues showing MutSα-dependent somatic instability, suggesting that they may act on the same lesion or structure associated with the expanded (GAA·TTC(n sequence. We conclude that Pms2 specifically suppresses large expansions of a pathogenic trinucleotide repeat sequence in neuronal tissues, possibly acting independently of the canonical MMR pathway.

Pms2 suppresses large expansions of the (GAA·TTC)n sequence in neuronal tissues.

Science.gov (United States)

Bourn, Rebecka L; De Biase, Irene; Pinto, Ricardo Mouro; Sandi, Chiranjeevi; Al-Mahdawi, Sahar; Pook, Mark A; Bidichandani, Sanjay I

2012-01-01

Expanded trinucleotide repeat sequences are the cause of several inherited neurodegenerative diseases. Disease pathogenesis is correlated with several features of somatic instability of these sequences, including further large expansions in postmitotic tissues. The presence of somatic expansions in postmitotic tissues is consistent with DNA repair being a major determinant of somatic instability. Indeed, proteins in the mismatch repair (MMR) pathway are required for instability of the expanded (CAG·CTG)(n) sequence, likely via recognition of intrastrand hairpins by MutSβ. It is not clear if or how MMR would affect instability of disease-causing expanded trinucleotide repeat sequences that adopt secondary structures other than hairpins, such as the triplex/R-loop forming (GAA·TTC)(n) sequence that causes Friedreich ataxia. We analyzed somatic instability in transgenic mice that carry an expanded (GAA·TTC)(n) sequence in the context of the human FXN locus and lack the individual MMR proteins Msh2, Msh6 or Pms2. The absence of Msh2 or Msh6 resulted in a dramatic reduction in somatic mutations, indicating that mammalian MMR promotes instability of the (GAA·TTC)(n) sequence via MutSα. The absence of Pms2 resulted in increased accumulation of large expansions in the nervous system (cerebellum, cerebrum, and dorsal root ganglia) but not in non-neuronal tissues (heart and kidney), without affecting the prevalence of contractions. Pms2 suppressed large expansions specifically in tissues showing MutSα-dependent somatic instability, suggesting that they may act on the same lesion or structure associated with the expanded (GAA·TTC)(n) sequence. We conclude that Pms2 specifically suppresses large expansions of a pathogenic trinucleotide repeat sequence in neuronal tissues, possibly acting independently of the canonical MMR pathway.

Parental decision-making in uptake of the MMR vaccination: a systematic review of qualitative literature.

Science.gov (United States)

Allan, N; Harden, J

2015-12-01

Controversy has surrounded MMR vaccination in the aftermath of Wakefield's 1998 paper suggesting links between MMR and the development of pervasive developmental disorder in children. The paper sparked off media debate and contributed to a lack of parental trust in health-care providers and reduction in MMR uptake. This review aims to identify and evaluate research on the subject, with a view to present the reasons behind, and influences on parental decision-making in relation to MMR. Systematic search strategy identified 14 relevant papers on which thematic analysis was performed. Themes identified were categorized as follows: perceptions of risk; roles and responsibility; experience and knowledge. There were limited changes in parental decision-making factors over the time period despite an increase in uptake. Many studies fail to differentiate between accepters and rejecters, making it difficult to draw out clear conclusions. Policymakers need to adapt information provided to address these concerns. Future research should focus more on distinguishing between accepters and rejecters to determine which factors can alter outcome. © The Author 2014. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

RNA-based mutation analysis identifies an unusual MSH6 splicing defect and circumvents PMS2 pseudogene interference.

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Etzler, J; Peyrl, A; Zatkova, A; Schildhaus, H-U; Ficek, A; Merkelbach-Bruse, S; Kratz, C P; Attarbaschi, A; Hainfellner, J A; Yao, S; Messiaen, L; Slavc, I; Wimmer, K

2008-02-01

Heterozygous germline mutations in one of the mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2 cause hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome, a dominantly inherited cancer susceptibility syndrome. Recent reports provide evidence for a novel recessively inherited cancer syndrome with constitutive MMR deficiency due to biallelic germline mutations in one of the MMR genes. MMR-deficiency (MMR-D) syndrome is characterized by childhood brain tumors, hematological and/or gastrointestinal malignancies, and signs of neurofibromatosis type 1 (NF1). We established an RNA-based mutation detection assay for the four MMR genes, since 1) a number of splicing defects may escape detection by the analysis of genomic DNA, and 2) DNA-based mutation detection in the PMS2 gene is severely hampered by the presence of multiple highly similar pseudogenes, including PMS2CL. Using this assay, which is based on direct cDNA sequencing of RT-PCR products, we investigated two families with children suspected to suffer from MMR-D syndrome. We identified a homozygous complex MSH6 splicing alteration in the index patients of the first family and a novel homozygous PMS2 mutation (c.182delA) in the index patient of the second family. Furthermore, we demonstrate, by the analysis of a PMS2/PMS2CL "hybrid" allele carrier, that RNA-based PMS2 testing effectively avoids the caveats of genomic DNA amplification approaches; i.e., pseudogene coamplification as well as allelic dropout, and will, thus, allow more sensitive mutation analysis in MMR deficiency and in HNPCC patients with PMS2 defects. (c) 2007 Wiley-Liss, Inc.

DNA repair systems as targets of cadmium toxicity

International Nuclear Information System (INIS)

Giaginis, Constantinos; Gatzidou, Elisavet; Theocharis, Stamatios

2006-01-01

Cadmium (Cd) is a heavy metal and a potent carcinogen implicated in tumor development through occupational and environmental exposure. Recent evidence suggests that proteins participating in the DNA repair systems, especially in excision and mismatch repair, are sensitive targets of Cd toxicity. Cd by interfering and inhibiting these DNA repair processes might contribute to increased risk for tumor formation in humans. In the present review, the information available on the interference of Cd with DNA repair systems and their inhibition is summarized. These actions could possibly explain the indirect contribution of Cd to mutagenic effects and/or carcinogenicity

The 116G > A MSH6 and IVS1-1121C > T PMS2 Genes Polymorphisms Modulate the Risk of the Sporadic Colorectal Cancer Development in Polish Population.

Science.gov (United States)

Zelga, Piotr; Przybyłowska-Sygut, Karolina; Zelga, Marta; Dziki, Adam; Majsterek, Ireneusz

2018-04-01

Colorectal cancer (CRC) is one of the most common cancers worldwide. DNA mismatch repair (MMR) is an evolutionarily conserved process that corrects mismatches generated during DNA replication. MMR defects were found to be associated with hereditary non-polyposis colorectal cancer (HNPCC) and a subset of sporadic colon cancers. The inheritance of common variations in MMR genes may influences individual susceptibility to the development of colorectal cancer. The purpose of the study was to evaluate the association between gene polymorphisms Glu39Gly (c.116G > A) of MSH6 gene and IVS1-1121C > T of PMS2 gene and sporadic colorectal cancer risk, in a case-control study comprising 200 patients and 200 controls origination from polish population. DNA was isolated from peripheral blood lymphocytes of enrolled patients, and gene polymorphisms were analysed by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) for MSH6 and TaqMan for PMS2. G/A variant of Glu39Gly (c.116G > A) genotype was associated with an increased risk of colorectal cancer (OR 1,65 95%CI:1,01-2,69 p = 0.44). Presence of A allele was also significantly higher in patient with CRC (OR 1,57 95% CI: 1,04-2,38 p = 0.032). Prevalence of this genotype was also markedly higher in females and patients above 60 years in CRC group (OR 2.25 95%CI: 1.22-4.14 p = 0.0098 and OR 2.74 95% CI: 1.27-5.93 p = 0.0097 respectively). None of such correlations was observed for genotype variants of IVS1-1121C > T PMS2. In conclusion, our data suggests thatMSH6 Glu39Gly polymorphism is associated with the risk of developing sporadic colorectal cancer in polish population. Linkage to the female gender, onset above 60 years old and further increase of risk when combined with wild-type allele of PMS2 IVS1-1121C > T polymorphism indicates defective mismatch repair system.

Single-molecule analysis reveals the kinetics and physiological relevance of MutL-ssDNA binding.

Directory of Open Access Journals (Sweden)

Jonghyun Park

2010-11-01

Full Text Available DNA binding by MutL homologs (MLH/PMS during mismatch repair (MMR has been considered based on biochemical and genetic studies. Bulk studies with MutL and its yeast homologs Mlh1-Pms1 have suggested an integral role for a single-stranded DNA (ssDNA binding activity during MMR. We have developed single-molecule Förster resonance energy transfer (smFRET and a single-molecule DNA flow-extension assays to examine MutL interaction with ssDNA in real time. The smFRET assay allowed us to observe MutL-ssDNA association and dissociation. We determined that MutL-ssDNA binding required ATP and was the greatest at ionic strength below 25 mM (K(D = 29 nM while it dramatically decreases above 100 mM (K(D>2 µM. Single-molecule DNA flow-extension analysis suggests that multiple MutL proteins may bind ssDNA at low ionic strength but this activity does not enhance stability at elevated ionic strengths. These studies are consistent with the conclusion that a stable MutL-ssDNA interaction is unlikely to occur at physiological salt eliminating a number of MMR models. However, the activity may infer some related dynamic DNA transaction process during MMR.

Tolerance of DNA Mismatches in Dmc1 Recombinase-mediated DNA Strand Exchange.

Science.gov (United States)

Borgogno, María V; Monti, Mariela R; Zhao, Weixing; Sung, Patrick; Argaraña, Carlos E; Pezza, Roberto J

2016-03-04

Recombination between homologous chromosomes is required for the faithful meiotic segregation of chromosomes and leads to the generation of genetic diversity. The conserved meiosis-specific Dmc1 recombinase catalyzes homologous recombination triggered by DNA double strand breaks through the exchange of parental DNA sequences. Although providing an efficient rate of DNA strand exchange between polymorphic alleles, Dmc1 must also guard against recombination between divergent sequences. How DNA mismatches affect Dmc1-mediated DNA strand exchange is not understood. We have used fluorescence resonance energy transfer to study the mechanism of Dmc1-mediated strand exchange between DNA oligonucleotides with different degrees of heterology. The efficiency of strand exchange is highly sensitive to the location, type, and distribution of mismatches. Mismatches near the 3' end of the initiating DNA strand have a small effect, whereas most mismatches near the 5' end impede strand exchange dramatically. The Hop2-Mnd1 protein complex stimulates Dmc1-catalyzed strand exchange on homologous DNA or containing a single mismatch. We observed that Dmc1 can reject divergent DNA sequences while bypassing a few mismatches in the DNA sequence. Our findings have important implications in understanding meiotic recombination. First, Dmc1 acts as an initial barrier for heterologous recombination, with the mismatch repair system providing a second level of proofreading, to ensure that ectopic sequences are not recombined. Second, Dmc1 stepping over infrequent mismatches is likely critical for allowing recombination between the polymorphic sequences of homologous chromosomes, thus contributing to gene conversion and genetic diversity. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

A homozygous PMS2 founder mutation with an attenuated constitutional mismatch repair deficiency phenotype.

Science.gov (United States)

Li, Lili; Hamel, Nancy; Baker, Kristi; McGuffin, Michael J; Couillard, Martin; Gologan, Adrian; Marcus, Victoria A; Chodirker, Bernard; Chudley, Albert; Stefanovici, Camelia; Durandy, Anne; Hegele, Robert A; Feng, Bing-Jian; Goldgar, David E; Zhu, Jun; De Rosa, Marina; Gruber, Stephen B; Wimmer, Katharina; Young, Barbara; Chong, George; Tischkowitz, Marc D; Foulkes, William D

2015-05-01

Inherited mutations in DNA mismatch repair genes predispose to different cancer syndromes depending on whether they are mono-allelic or bi-allelic. This supports a causal relationship between expression level in the germline and phenotype variation. As a model to study this relationship, our study aimed to define the pathogenic characteristics of a recurrent homozygous coding variant in PMS2 displaying an attenuated phenotype identified by clinical genetic testing in seven Inuit families from Northern Quebec. Pathogenic characteristics of the PMS2 mutation NM_000535.5:c.2002A>G were studied using genotype-phenotype correlation, single-molecule expression detection and single genome microsatellite instability analysis. This PMS2 mutation generates a de novo splice site that competes with the authentic site. In homozygotes, expression of the full-length protein is reduced to a level barely detectable by conventional diagnostics. Median age at primary cancer diagnosis is 22 years among 13 NM_000535.5:c.2002A>G homozygotes, versus 8 years in individuals carrying bi-allelic truncating mutations. Residual expression of full-length PMS2 transcript was detected in normal tissues from homozygotes with cancers in their 20s. Our genotype-phenotype study of c.2002A>G illustrates that an extremely low level of PMS2 expression likely delays cancer onset, a feature that could be exploited in cancer preventive intervention. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Role for cER and Mmr1p in anchorage of mitochondria at sites of polarized surface growth in budding yeast.

Science.gov (United States)

Swayne, Theresa C; Zhou, Chun; Boldogh, Istvan R; Charalel, Joseph K; McFaline-Figueroa, José Ricardo; Thoms, Sven; Yang, Christine; Leung, Galen; McInnes, Joseph; Erdmann, Ralf; Pon, Liza A

2011-12-06

Mitochondria accumulate at neuronal and immunological synapses and yeast bud tips and associate with the ER during phospholipid biosynthesis, calcium homeostasis, and mitochondrial fission. Here we show that mitochondria are associated with cortical ER (cER) sheets underlying the plasma membrane in the bud tip and confirm that a deletion in YPT11, which inhibits cER accumulation in the bud tip, also inhibits bud tip anchorage of mitochondria. Time-lapse imaging reveals that mitochondria are anchored at specific sites in the bud tip. Mmr1p, a member of the DSL1 family of tethering proteins, localizes to punctate structures on opposing surfaces of mitochondria and cER sheets underlying the bud tip and is recovered with isolated mitochondria and ER. Deletion of MMR1 impairs bud tip anchorage of mitochondria without affecting mitochondrial velocity or cER distribution. Deletion of the phosphatase PTC1 results in increased Mmr1p phosphorylation, mislocalization of Mmr1p, defects in association of Mmr1p with mitochondria and ER, and defects in bud tip anchorage of mitochondria. These findings indicate that Mmr1p contributes to mitochondrial inheritance as a mediator of anchorage of mitochondria to cER sheets in the yeast bud tip and that Ptc1p regulates Mmr1p phosphorylation, localization, and function. Copyright © 2011 Elsevier Ltd. All rights reserved.

A novel measles outbreak control strategy in the Netherlands in 2013-2014 using a national electronic immunization register: A study of early MMR uptake and its determinants.

Science.gov (United States)

Nic Lochlainn, Laura M; Woudenberg, Tom; van Lier, Alies; Zonnenberg, Irmgard; Philippi, Marvin; de Melker, Hester E; Hahné, Susan J M

2017-10-13

During a large measles outbreak in the Netherlands in 2013-2014, infants aged 6-14months living in municipalities with low (<90%) measles-mumps-rubella (MMR) coverage were individually invited for an early MMR using the national electronic immunization register, Præventis. We estimated uptake of early MMR prior to and during the 2013-2014 outbreak and assessed determinants for early MMR vaccination. We obtained vaccination records from Præventis, and defined early MMR as vaccination before 415days (13months) of age. A multi-level multivariable logistic regression model, restricted to infants with three diphtheria-pertussis-tetanus-polio (DPTP) vaccinations was used to examine the association between early MMR uptake and sex, parents' country of birth, socioeconomic status (SES; at postcode level) and voting proportions for the Reformed Political Party (SGP; at municipal level), used as a proxy for religious objections towards vaccination. In the 29 municipalities with low MMR coverage, uptake of early MMR was 0.5-2.2% prior to the outbreak. Between July 2013 and March 2014, 5,800 (57%) invited infants received an early MMR. Among infants with three DPTP, 70% received an early MMR. Only 1% of infants without prior DPTP received an early MMR. Lower early MMR uptake was associated with a higher SGP voter-ship (OR 0.89 per 5% increase, 95%CI 0.83-0.96), parents' with unknown country of birth (OR 0.66 95%CI 0.47-0.93) and compared with very high SES, high SES had significantly lower early MMR uptake (OR 0.66 95%CI 0.50-0.87). This is the first study describing use of Præventis during an outbreak and to assess determinants of early MMR uptake. More than half of invited infants obtained an early MMR. SES, parents' with unknown country of birth and religious objections towards vaccination were found to be associated with lower early MMR uptake. In future outbreaks, these determinants could be used to tailor intervention strategies. Copyright © 2017. Published by

Information, education, and health behaviors: Evidence from the MMR vaccine autism controversy.

Science.gov (United States)

Chang, Lenisa V

2018-05-02

In the wake of strong, although later refuted, claims of a link between autism and the measles-mumps-rubella (MMR) vaccine, I examine whether fewer parents immunized or delayed vaccinations for their children and if there was a differential response by mother's education level. Using various controls and a differencing strategy that compares in MMR take-up with other vaccines, I find that the MMR-autism controversy led to a decline in the immediate years and that there were negative spillovers onto other vaccines. I also find evidence that more highly educated mothers responded more strongly to the controversy either by not immunizing their children altogether or, to a lesser degree, delaying vaccination. Moreover, the educational gap was greater in states where there was greater media attention devoted to the controversy. This is consistent with the health allocative efficiency hypothesis whereby part of the education gradient in health outcomes is due to more-educated individuals absorbing and responding to health information more quickly. However, unlike in the United Kingdom, where previous studies find that the gap was eliminated after the link was refuted, the evidence for the United States suggests that the educational gap persisted. Copyright © 2018 John Wiley & Sons, Ltd.

Decreased transcription-coupled nucleotide excision repair capacity is associated with increased p53- and MLH1-independent apoptosis in response to cisplatin

International Nuclear Information System (INIS)

Stubbert, Lawton J; Smith, Jennifer M; McKay, Bruce C

2010-01-01

One of the most commonly used classes of anti-cancer drugs presently in clinical practice is the platinum-based drugs, including cisplatin. The efficacy of cisplatin therapy is often limited by the emergence of resistant tumours following treatment. Cisplatin resistance is multi-factorial but can be associated with increased DNA repair capacity, mutations in p53 or loss of DNA mismatch repair capacity. RNA interference (RNAi) was used to reduce the transcription-coupled nucleotide excision repair (TC-NER) capacity of several prostate and colorectal carcinoma cell lines with specific defects in p53 and/or DNA mismatch repair. The effect of small inhibitory RNAs designed to target the CSB (Cockayne syndrome group B) transcript on TC-NER and the sensitivity of cells to cisplatin-induced apoptosis was determined. These prostate and colon cancer cell lines were initially TC-NER proficient and RNAi against CSB significantly reduced their DNA repair capacity. Decreased TC-NER capacity was associated with an increase in the sensitivity of tumour cells to cisplatin-induced apoptosis, even in p53 null and DNA mismatch repair-deficient cell lines. The present work indicates that CSB and TC-NER play a prominent role in determining the sensitivity of tumour cells to cisplatin even in the absence of p53 and DNA mismatch repair. These results further suggest that CSB represents a potential target for cancer therapy that may be important to overcome resistance to cisplatin in the clinic

Decreased transcription-coupled nucleotide excision repair capacity is associated with increased p53- and MLH1-independent apoptosis in response to cisplatin

Directory of Open Access Journals (Sweden)

Smith Jennifer M

2010-05-01

Full Text Available Abstract Background One of the most commonly used classes of anti-cancer drugs presently in clinical practice is the platinum-based drugs, including cisplatin. The efficacy of cisplatin therapy is often limited by the emergence of resistant tumours following treatment. Cisplatin resistance is multi-factorial but can be associated with increased DNA repair capacity, mutations in p53 or loss of DNA mismatch repair capacity. Methods RNA interference (RNAi was used to reduce the transcription-coupled nucleotide excision repair (TC-NER capacity of several prostate and colorectal carcinoma cell lines with specific defects in p53 and/or DNA mismatch repair. The effect of small inhibitory RNAs designed to target the CSB (Cockayne syndrome group B transcript on TC-NER and the sensitivity of cells to cisplatin-induced apoptosis was determined. Results These prostate and colon cancer cell lines were initially TC-NER proficient and RNAi against CSB significantly reduced their DNA repair capacity. Decreased TC-NER capacity was associated with an increase in the sensitivity of tumour cells to cisplatin-induced apoptosis, even in p53 null and DNA mismatch repair-deficient cell lines. Conclusion The present work indicates that CSB and TC-NER play a prominent role in determining the sensitivity of tumour cells to cisplatin even in the absence of p53 and DNA mismatch repair. These results further suggest that CSB represents a potential target for cancer therapy that may be important to overcome resistance to cisplatin in the clinic.

Bi-directional routing of DNA mismatch repair protein human exonuclease 1 to replication foci and DNA double strand breaks

DEFF Research Database (Denmark)

Liberti, Sascha E; Andersen, Sofie Dabros; Wang, Jing

2011-01-01

(PIP-box) region on hEXO1 located in its COOH-terminal ((788)QIKLNELW(795)). This motif is essential for PCNA binding and co-localization during S-phase. Recruitment of hEXO1 to DNA DSB sites is dependent on the MMR protein hMLH1. We show that two distinct hMLH1 interaction regions of hEXO1 (residues...

MMR (measles, mumps, and rubella) vaccine - what you need to know

Science.gov (United States)

... taken in its entirety from the CDC MMR (Measles, Mumps, & Rubella) Vaccine Information Statement (VIS): www.cdc. ... Why get vaccinated? Measles, mumps, and rubella are viral diseases that can ... Before vaccines, these diseases were very common in ...

DNA repair in Mycobacterium tuberculosis revisited.

Science.gov (United States)

Dos Vultos, Tiago; Mestre, Olga; Tonjum, Tone; Gicquel, Brigitte

2009-05-01

Our understanding of Mycobacterium tuberculosis DNA repair mechanisms is still poor compared with that of other bacterial organisms. However, the publication of the first complete M. tuberculosis genome sequence 10 years ago boosted the study of DNA repair systems in this organism. A first step in the elucidation of M. tuberculosis DNA repair mechanisms was taken by Mizrahi and Andersen, who identified homologs of genes involved in the reversal or repair of DNA damage in Escherichia coli and related organisms. Genes required for nucleotide excision repair, base excision repair, recombination, and SOS repair and mutagenesis were identified. Notably, no homologs of genes involved in mismatch repair were identified. Novel characteristics of the M. tuberculosis DNA repair machinery have been found over the last decade, such as nonhomologous end joining, the presence of Mpg, ERCC3 and Hlr - proteins previously presumed to be produced exclusively in mammalian cells - and the recently discovered bifunctional dCTP deaminase:dUTPase. The study of these systems is important to develop therapeutic agents that can counteract M. tuberculosis evolutionary changes and to prevent adaptive events resulting in antibiotic resistance. This review summarizes our current understanding of the M. tuberculosis DNA repair system.

Differential cellular responses to prolonged LDR-IR in MLH1-proficient and MLH1-deficient colorectal cancer HCT116 cells.

Science.gov (United States)

Yan, Tao; Seo, Yuji; Kinsella, Timothy J

2009-11-15

MLH1 is a key DNA mismatch repair (MMR) protein involved in maintaining genomic stability by participating in the repair of endogenous and exogenous mispairs in the daughter strands during S phase. Exogenous mispairs can result following treatment with several classes of chemotherapeutic drugs, as well as with ionizing radiation. In this study, we investigated the role of the MLH1 protein in determining the cellular and molecular responses to prolonged low-dose rate ionizing radiation (LDR-IR), which is similar to the clinical use of cancer brachytherapy. An isogenic pair of MMR(+) (MLH1(+)) and MMR(-) (MLH1(-)) human colorectal cancer HCT116 cells was exposed to prolonged LDR-IR (1.3-17 cGy/h x 24-96 h). The clonogenic survival and gene mutation rates were examined. Cell cycle distribution was analyzed with flow cytometry. Changes in selected DNA damage repair proteins, DNA damage response proteins, and cell death marker proteins were examined with Western blotting. MLH1(+) HCT116 cells showed greater radiosensitivity with enhanced expression of apoptotic and autophagic markers, a reduced HPRT gene mutation rate, and more pronounced cell cycle alterations (increased late-S population and a G(2)/M arrest) following LDR-IR compared with MLH1(-) HCT116 cells. Importantly, a progressive increase in MLH1 protein levels was found in MLH1(+) cells during prolonged LDR-IR, which was temporally correlated with a progressive decrease in Rad51 protein (involved in homologous recombination) levels. MLH1 status significantly affects cellular responses to prolonged LDR-IR. MLH1 may enhance cell radiosensitivity to prolonged LDR-IR through inhibition of homologous recombination (through inhibition of Rad51).

[The relationship between MMR vaccination level and the number of new cases of autism in children].

Science.gov (United States)

Mrozek-Budzyn, Dorota; Kiełtyka, Agnieszka

2008-01-01

The MMR vaccination coverage in Malopolskie voivodeship improved rapidly and finally reached a high level during last years. The number of new cases of autism spectrum disorders in children during that time revealed a slightly rising but not significant trend, while the number of childhood autism were stable. Ecological study showed no correlation between MMR vaccination and an increased risk of childhood autism and autism spectrum disorders in children.

Intralesional tuberculin (PPD) versus measles, mumps, rubella (MMR) vaccine in treatment of multiple warts: a comparative clinical and immunological study.

Science.gov (United States)

Shaheen, Maha Adel; Salem, Samar Abdallah M; Fouad, Dina Adel; El-Fatah, Abeer Aly Abd

2015-01-01

Intralesional purified protein derivative (PPD) or mumps, measles, rubella (MMR) were not previously compared regarding their efficacy or mechanism of action in treatment of warts. We aimed to compare their efficacy in treatment of multiple warts and investigate their effect on serum interleukin (IL)-4 and IL-12. Thirty patients with multiple warts were included (10 treated with PPD, 10 with MMR, and 10 with normal saline (control)). Injection was done every 3 weeks until clearance or maximum of three treatments. Clinical response of target and distant warts was evaluated. Serum ILs-4 and -12 were assessed before and after treatment. A significantly higher rate of complete response was found in target and distant warts with PPD (60% each) and MMR (80%, 40%, respectively) compared with controls (0%), with no significant difference between both treatments. After treatment, the control group showed the lowest serum IL-12 and IL-4 levels compared with the MMR- and PPD-treated groups with statistically significant difference in between. MMR resulted in a significantly higher serum IL-12 than PPD. With PPD, IL-4 was increased with statistically significant change compared with pretreat-ment level. Intralesional PPD and MMR show comparable efficacy and safety in treatment of multiple warts. Serum ILs-4 and-12 increase following antigen injection. © 2015 Wiley Periodicals, Inc.

Detailed characterization of MLH1 p.D41H and p.N710D variants coexisting in a Lynch syndrome family with conserved MLH1 expression tumors.

Science.gov (United States)

Pineda, M; González-Acosta, M; Thompson, B A; Sánchez, R; Gómez, C; Martínez-López, J; Perea, J; Caldés, T; Rodríguez, Y; Landolfi, S; Balmaña, J; Lázaro, C; Robles, L; Capellá, G; Rueda, D

2015-06-01

Lynch syndrome (LS) is an autosomal dominant cancer-susceptibility disease caused by inactivating germline mutations in mismatch repair (MMR) genes. Variants of unknown significance (VUS) are often detected in mutational analysis of MMR genes. Here we describe a large family fulfilling Amsterdam I criteria carrying two rare VUS in the MLH1 gene: c.121G > C (p.D41H) and c.2128A > G (p.N710D). Collection of clinico-pathological data, multifactorial analysis, in silico predictions, and functional analyses were used to elucidate the clinical significance of the identified MLH1 VUS. Only the c.121G > C variant cosegregated with LS-associated tumors in the family. Diagnosed colorectal tumors were microsatellite unstable although immunohistochemical staining revealed no loss of MMR proteins expression. Multifactorial likelihood analysis classified c.2128A > G as a non-pathogenic variant and c.121G > C as pathogenic. In vitro functional tests revealed impaired MMR activity and diminished expression of c.121G > C. Accordingly, the N710 residue is located in the unconserved MLH1 C-terminal domain, whereas D41 is highly conserved and located in the ATPase domain. The obtained results will enable adequate genetic counseling of c.121G > C and c.2128A > G variant carriers and their families. Furthermore, they exemplify how cumulative data and comprehensive analyses are mandatory to refine the classification of MMR variants. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

DEVELOPMENT AND DEPLOYMENT ASSESSMENT OF A MELT-DOWN PROOF MODULAR MICRO REACTOR (MDP-MMR)

Energy Technology Data Exchange (ETDEWEB)

Hawari, Ayman I.; Venneri, Francesco

2018-04-02

The objective of this project is to perform feasibility assessment and technology gap analysis and establish a development roadmap for an innovative and highly compact Micro Modular Reactor (MMR) concept that integrates power production, power conversion and electricity generation in a single unit. The MMR is envisioned to use fully ceramic micro-encapsulated (FCM) fuel, a particularly robust form of TRISO fuel, and to be gas-cooled (e.g., He or CO2) and capable of generating power in the range of 10 to 40 MW-thermal. It is designed to be absolutely melt-down proof (MDP) under all circumstances including complete loss of coolant scenarios with no possible release of radioactive material, to be factory produced, to have a cycle length of greater than 20 years, and to be highly proliferation resistant. In addition, it will be transportable, retrievable and suitable for use in remote areas. As such, the MDP-MMR will represent a versatile reactor concept that is suitable for use in various applications including electricity generation, process heat utilization and propulsion.

A review of statistical methods for testing genetic anticipation: looking for an answer in Lynch syndrome

DEFF Research Database (Denmark)

Boonstra, Philip S; Gruber, Stephen B; Raymond, Victoria M

2010-01-01

the issue of multiplex ascertainment and its effect on the different methods. We then focus on exploring genetic anticipation in Lynch syndrome and analyze new data on the age of onset in affected parent-child pairs from families seen at the University of Michigan Cancer Genetics clinic with a mutation...... in one of the three main mismatch repair (MMR) genes. In contrast to the clinic-based population, we re-analyze data on a population-based Lynch syndrome cohort, derived from the Danish HNPCC-register. Both datasets indicate evidence of genetic anticipation in Lynch syndrome. We then expand our review...

The two-dose measles, mumps, and rubella (MMR) immunisation schedule: factors affecting maternal intention to vaccinate.

OpenAIRE

Pareek, M; Pattison, H M

2000-01-01

BACKGROUND: In the light of sub-optimal uptake of the measles, mumps, and rubella (MMR) vaccination, we investigated the factors that influence the intentions of mothers to vaccinate. METHOD: A cross-sectional survey of 300 mothers in Birmingham with children approaching a routine MMR vaccination was conducted using a postal questionnaire to measure: intention to vaccinate, psychological variables, knowledge of the vaccine, and socioeconomic status. The vaccination status of the children was ...

Autism occurrence by MMR vaccine status among US children with older siblings with and without autism.

Science.gov (United States)

Jain, Anjali; Marshall, Jaclyn; Buikema, Ami; Bancroft, Tim; Kelly, Jonathan P; Newschaffer, Craig J

2015-04-21

Despite research showing no link between the measles-mumps-rubella (MMR) vaccine and autism spectrum disorders (ASD), beliefs that the vaccine causes autism persist, leading to lower vaccination levels. Parents who already have a child with ASD may be especially wary of vaccinations. To report ASD occurrence by MMR vaccine status in a large sample of US children who have older siblings with and without ASD. A retrospective cohort study using an administrative claims database associated with a large commercial health plan. Participants included children continuously enrolled in the health plan from birth to at least 5 years of age during 2001-2012 who also had an older sibling continuously enrolled for at least 6 months between 1997 and 2012. MMR vaccine receipt (0, 1, 2 doses) between birth and 5 years of age. ASD status defined as 2 claims with a diagnosis code in any position for autistic disorder or other specified pervasive developmental disorder (PDD) including Asperger syndrome, or unspecified PDD (International Classification of Diseases, Ninth Revision, Clinical Modification 299.0x, 299.8x, 299.9x). Of 95,727 children with older siblings, 994 (1.04%) were diagnosed with ASD and 1929 (2.01%) had an older sibling with ASD. Of those with older siblings with ASD, 134 (6.9%) had ASD, vs 860 (0.9%) children with unaffected siblings (P siblings, vs 73% (n = 1409) at age 2 years and 86% (n = 1660) at age 5 years for children with affected siblings. MMR vaccine receipt was not associated with an increased risk of ASD at any age. For children with older siblings with ASD, at age 2, the adjusted relative risk (RR) of ASD for 1 dose of MMR vaccine vs no vaccine was 0.76 (95% CI, 0.49-1.18; P = .22), and at age 5, the RR of ASD for 2 doses compared with no vaccine was 0.56 (95% CI, 0.31-1.01; P = .052). For children whose older siblings did not have ASD, at age 2, the adjusted RR of ASD for 1 dose was 0.91 (95% CI, 0.67-1.20; P = .50) and at age 5

Intentions to use a novel Zika vaccine: the effects of misbeliefs about the MMR vaccine and perceptions about Zika.

Science.gov (United States)

Ophir, Yotam; Jamieson, Kathleen Hall

2018-03-15

People's intentions to use vaccines are influenced by their beliefs about both the specific vaccine and the disease it prevents. In the absence of firm beliefs about Zika virus (ZIKV), individuals may base their intentions to vaccinate against it on beliefs about other vaccines, and specifically the misbelief that MMR causes autism. A survey of 3337 Americans, using a random-digit-dialing sample of landline telephone households and cell-phones. Intentions to use a Zika vaccine were influenced by beliefs about Zika, science in general, and MMR. Intentions were positively influenced by perceived severity of and vulnerability to Zika, as well as belief in science's efficacy. However, intentions were negatively influenced by the belief that MMR causes autism in children. The misbelief about MMR and autism may reduce people's intentions to use a new Zika vaccine. However, perceptions of severity of and vulnerability to Zika may increase intentions. Implications for science educators and public health officials are discussed.