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Daniels HG, Knicely BG, Miller AK, Thompson A, Plattner R, Goellner EM. Inhibition of ABL1 by tyrosine kinase inhibitors leads to a downregulation of MLH1 by Hsp70-mediated lysosomal protein degradation. Front Genet 2022; 13:940073. [PMID: 36338985 PMCID: PMC9631443 DOI: 10.3389/fgene.2022.940073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/03/2022] [Indexed: 01/07/2023] Open
Abstract
The DNA mismatch repair (MMR) pathway and its regulation are critical for genomic stability. Mismatch repair (MMR) follows replication and repairs misincorporated bases and small insertions or deletions that are not recognized and removed by the proofreading polymerase. Cells deficient in MMR exhibit an increased overall mutation rate and increased expansion and contraction of short repeat sequences in the genome termed microsatellite instability (MSI). MSI is often a clinical measure of genome stability in tumors and is used to determine the course of treatment. MMR is also critical for inducing apoptosis after alkylation damage from environmental agents or DNA-damaging chemotherapy. MLH1 is essential for MMR, and loss or mutation of MLH1 leads to defective MMR, increased mutation frequency, and MSI. In this study, we report that tyrosine kinase inhibitors, imatinib and nilotinib, lead to decreased MLH1 protein expression but not decreased MLH1 mRNA levels. Of the seven cellular targets of Imatinib and nilotinib, we show that silencing of ABL1 also reduces MLH1 protein expression. Treatment with tyrosine kinase inhibitors or silencing of ABL1 results in decreased apoptosis after treatment with alkylating agents, suggesting the level of MLH1 reduction is sufficient to disrupt MMR function. We also report MLH1 is tyrosine phosphorylated by ABL1. We demonstrate that MLH1 downregulation by ABL1 knockdown or inhibition requires chaperone protein Hsp70 and that MLH1 degradation can be abolished with the lysosomal inhibitor bafilomycin. Taken together, we propose that ABL1 prevents MLH1 from being targeted for degradation by the chaperone Hsp70 and that in the absence of ABL1 activity at least a portion of MLH1 is degraded through the lysosome. This study represents an advance in understanding MMR pathway regulation and has important clinical implications as MMR status is used in the clinic to inform patient treatment, including the use of immunotherapy.
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Affiliation(s)
- Hannah G. Daniels
- University of Kentucky, College of Medicine Department of Toxicology and Cancer Biology, Lexington, KY, United States
| | - Breanna G. Knicely
- University of Kentucky, College of Medicine Department of Toxicology and Cancer Biology, Lexington, KY, United States
| | - Anna Kristin Miller
- University of Kentucky, College of Medicine Department of Toxicology and Cancer Biology, Lexington, KY, United States
| | - Ana Thompson
- Berea College, Berea, KY, United States,University of Kentucky Markey Cancer Center, Lexington, KY, United States
| | - Rina Plattner
- University of Kentucky Markey Cancer Center, Lexington, KY, United States,University of Kentucky, College of Medicine Department of Pharmacology and Nutritional Sciences, Lexington, KY, United States
| | - Eva M. Goellner
- University of Kentucky, College of Medicine Department of Toxicology and Cancer Biology, Lexington, KY, United States,University of Kentucky Markey Cancer Center, Lexington, KY, United States,*Correspondence: Eva M. Goellner,
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Miller AK, Mao G, Knicely BG, Daniels HG, Rahal C, Putnam CD, Kolodner RD, Goellner EM. Rad5 and Its Human Homologs, HLTF and SHPRH, Are Novel Interactors of Mismatch Repair. Front Cell Dev Biol 2022; 10:843121. [PMID: 35784486 PMCID: PMC9243396 DOI: 10.3389/fcell.2022.843121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 05/16/2022] [Indexed: 12/02/2022] Open
Abstract
DNA mismatch repair (MMR) repairs replication errors, and MMR defects play a role in both inherited cancer predisposition syndromes and in sporadic cancers. MMR also recognizes mispairs caused by environmental and chemotherapeutic agents; however, in these cases mispair recognition leads to apoptosis and not repair. Although mutation avoidance by MMR is fairly well understood, MMR-associated proteins are still being identified. We performed a bioinformatic analysis that implicated Saccharomyces cerevisiae Rad5 as a candidate for interacting with the MMR proteins Msh2 and Mlh1. Rad5 is a DNA helicase and E3 ubiquitin ligase involved in post-replicative repair and damage tolerance. We confirmed both interactions and found that the Mlh1 interaction is mediated by a conserved Mlh1-interacting motif (MIP box). Despite this, we did not find a clear role for Rad5 in the canonical MMR mutation avoidance pathway. The interaction of Rad5 with Msh2 and Mlh1 is conserved in humans, although each of the Rad5 human homologs, HLTF and SHPRH, shared only one of the interactions: HLTF interacts with MSH2, and SHPRH interacts with MLH1. Moreover, depletion of SHPRH, but not HLTF, results in a mild increase in resistance to alkylating agents although not as strong as loss of MMR, suggesting gene duplication led to specialization of the MMR-protein associated roles of the human Rad5 homologs. These results provide insights into how MMR accessory factors involved in the MMR-dependent apoptotic response interact with the core MMR machinery and have important health implications into how human cells respond to environmental toxins, tumor development, and treatment choices of tumors with defects in Rad5 homologs.
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Affiliation(s)
- Anna K. Miller
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Guogen Mao
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Breanna G. Knicely
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Hannah G. Daniels
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Christine Rahal
- Ludiwg Institute for Cancer Research San Diego, San Diego, CA, United States
| | - Christopher D. Putnam
- Ludiwg Institute for Cancer Research San Diego, San Diego, CA, United States
- Department of Medicine, University of California San Diego, San Diego, CA, United States
| | - Richard D. Kolodner
- Ludiwg Institute for Cancer Research San Diego, San Diego, CA, United States
- Moores-UCSD Cancer Center, San Diego, CA, United States
- Institute of Genomic Medicine, San Diego, CA, United States
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, CA, United States
| | - Eva M. Goellner
- College of Medicine Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
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Wensink E, Bond M, Kucukkose E, May A, Vink G, Koopman M, Kranenburg O, Roodhart J. A review of the sensitivity of metastatic colorectal cancer patients with deficient mismatch repair to standard-of-care chemotherapy and monoclonal antibodies, with recommendations for future research. Cancer Treat Rev 2021; 95:102174. [PMID: 33721596 DOI: 10.1016/j.ctrv.2021.102174] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 02/17/2021] [Accepted: 02/19/2021] [Indexed: 12/29/2022]
Abstract
In 5% of metastatic colorectal cancer (mCRC) patients, tumours display a deficient mismatch repair (dMMR) system. Immunotherapy is beneficial in dMMR mCRC patients and has recently been approved by the Food and Drug Administration for patients with unresectable or metastatic dMMR CRC. Although dMMR and proficient MMR (pMMR) CRC tumours are biologically distinct, they are commonly treated with the same chemotherapy and monoclonal antibodies. This includes dMMR mCRC patients who did not respond to immunotherapy (20-30%). However, it is unclear if these treatments are equally beneficial in dMMR mCRC. Of note, dMMR mCRC patients have a worse prognosis compared to pMMR, which may in part be caused by a lower response to treatment. To avoid unnecessary exposure to ineffective treatments and their associated toxicity, it is important to identify which systemic treatments are most beneficial in dMMR mCRC patients, thus improving their outcome. Indeed, future treatment strategies are likely to involve combinations of immunotherapy, chemotherapy and monoclonal antibodies. In this evidence-based review, we summarize clinical trials reporting treatment efficacy of different types of chemotherapy and monoclonal antibodies in dMMR mCRC patients. We also review the biological rationale behind a potential differential benefit of chemotherapy with or without monoclonal antibodies in dMMR mCRC patients. A barrier in the interpretation of preclinical results is the choice of model systems. They largely comprise traditional models, including cell lines and xenografts, rather than more representative models, such as patient-derived organoids. We provide concrete recommendations for clinical investigators and fundamental researchers to accelerate research regarding which systemic therapy is most effective in dMMR mCRC patients.
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Affiliation(s)
- Emerens Wensink
- Department of Medical Oncology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584CX Utrecht, the Netherlands
| | - Marinde Bond
- Department of Medical Oncology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Universiteitsweg 100, 3584CX Utrecht, the Netherlands
| | - Emre Kucukkose
- Department of Surgical Oncology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584CX Utrecht, the Netherlands
| | - Anne May
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Universiteitsweg 100, 3584CX Utrecht, the Netherlands
| | - Geraldine Vink
- Department of Medical Oncology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Department of Research and Development, Netherlands Comprehensive Cancer Organisation, Godebaldkwartier 419, 3511DT Utrecht, the Netherlands
| | - Miriam Koopman
- Department of Medical Oncology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584CX Utrecht, the Netherlands
| | - Onno Kranenburg
- Department of Surgical Oncology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Utrecht Platform for Organoid Technology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584CX Utrecht, the Netherlands
| | - Jeanine Roodhart
- Department of Medical Oncology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584CX Utrecht, the Netherlands.
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Goellner EM. Chromatin remodeling and mismatch repair: Access and excision. DNA Repair (Amst) 2019; 85:102733. [PMID: 31698199 DOI: 10.1016/j.dnarep.2019.102733] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/06/2019] [Accepted: 10/09/2019] [Indexed: 01/03/2023]
Abstract
DNA mismatch repair (MMR) increases replication fidelity and genome stability by correcting DNA polymerase errors that remain after replication. Defects in MMR result in the accumulation of mutations and lead to human tumor development. Germline mutations in MMR cause the hereditary cancer syndrome, Lynch syndrome. After replication, DNA is reorganized into its chromatin structure and wrapped around histone octamers. DNA MMR is thought to be less efficient in recognizing and repairing mispairs packaged in chromatin, in which case MMR must either compete for access to naked DNA before histone deposition or actively move nucleosomes to access the mispair. This article reviews studies into the mechanistic and physical interactions between MMR and various chromatin-associated factors, including the histone deposition complex CAF1. Recent Xenopus and Saccharomyces cerevisiae studies describe a physical interaction between Msh2 and chromatin-remodeling ATPase Fun30/SMARCAD1, with potential mechanistic roles for SMARCAD1 in moving histones for both mispair access and excision tract elongation. The RSC complex, another histone remodeling complex, also potentially influences excision tract length. Deletion mutations of RSC2 point to mechanistic interactions with the MMR pathways. Together, these studies paint a picture of complex interactions between MMR and the chromatin environment that will require numerous additional genetic, biochemical, and cell biology experiments to fully understand. Understanding how these pathways interconnect is essential in fully understanding eukaryotic MMR and has numerous implications in human tumor formation and treatment.
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Affiliation(s)
- Eva M Goellner
- Department of Toxicology and Cancer Biology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40536, USA.
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Abstract
Lynch Syndrome (LS) is the most common dominantly inherited colorectal cancer (CRC) predisposition and is caused by a heterozygous germline defect in one of the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6, or PMS2. High microsatellite instability (MSI-H) and loss of MMR protein expression in tumours reflecting a defective MMR are indicators for LS, as well as a positive family history of early onset CRC. MSH2 and MSH6 form a major functional heterodimer, and MSH3 is an alternative binding partner for MSH2. So far, the role of germline MSH3 variants remains unclear, as to our knowledge heterozygous truncating variants are not regarded causative for LS, but were detected in patients with CRC, and recently biallelic MSH3 defects have been identified in two patients with adenomatous polyposis. By gene screening we investigated the role of MSH3 in 11 LS patients with truncating MSH6 germline variants and an unexplained MSH2 protein loss in their corresponding MSI-H tumours. We report the first two LS patients harbouring heterozygous germline variants c.1035del and c.2732T>G in MSH3 coincidentally with truncating variants in MSH6. In the patient with truncating germline variants in MSH3 and MSH6, two additional somatic second hits in both genes abrogate all binding partners for the MSH2 protein which might subsequently be degraded. The clinical relevance of MSH3 germline variants is currently under re-evaluation, and heterozygous MSH3 defects alone do not seem to induce a LS phenotype, but might aggravate the MSH6 phenotype in affected family members.
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Cama A, Genuardi M, Guanti G, Radice P, Varesco L. Molecular Genetics of Hereditary Non-Polyposis Colorectal Cancer (HNPCC). TUMORI JOURNAL 2018; 82:122-35. [PMID: 8644374 DOI: 10.1177/030089169608200206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The story of the molecular genetics of HNPCC is one of astonishingly rapid achievements. In just 16 months, from May 1993 to September 1994, four different genes, namely hMSH2, hMLH1, hPMS1 and hPMS2 have been identified and demonstrated to be associated with the disease. Their cloning was facilitated by the finding that tumor cells in HNPCC patients display a hypermutability of DNA short tandem repeats (microsatellite instability). In fact, HNPCC associated genes are the human counterparts of genetic elements known to control the fidelity of DNA replication in lower organisms. So far, more than 50 germline mutations of hMSH2 and hMLH1 genes have been reported in HNPCC kindreds. In addition, somatic mutations have been documented in hereditary as well as sporadic cancers. Unfortunately, the molecular diagnosis of HNPCC is hampered by the lack of mutational “hot spots” and of clearly defined genotype-phenotype correlations and different screening methods are to be employed for the analysis of affected and at-risk individuals.
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Affiliation(s)
- A Cama
- Cattedra di Patologia Generale, Università Gabriele D'Annuzio, Chieti,Italy
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Abstract
Starting from a survey of the studies on familial aggregation of colorectal cancer, we introduce the aims of genetic epidemiology. One of its main goals is to assess population frequency of cancer susceptibility genes and to determine the age-specific risks for carriers with respect to non-carriers. In section two, segregation analysis investigations are reviewed, and inferences on the relevance of genetic components of susceptibility to colorectal cancer are drawn. In section three, the HNPCC paradigm is discussed in the light of the Knudson model of tumorigenesis and recent advances of molecular research. In the last section we show an example of genotype/environment interaction in the etiology of a particular cancer and present a conceptual framework for studies on cancer genetic epidemiology in terms of attributable and relative risk.
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Affiliation(s)
- S Presciuttini
- Dipartimento di Scienze dell'Ambiente e del Territorio, Pisa, Italy
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Sveen A, Johannessen B, Tengs T, Danielsen SA, Eilertsen IA, Lind GE, Berg KCG, Leithe E, Meza-Zepeda LA, Domingo E, Myklebost O, Kerr D, Tomlinson I, Nesbakken A, Skotheim RI, Lothe RA. Multilevel genomics of colorectal cancers with microsatellite instability-clinical impact of JAK1 mutations and consensus molecular subtype 1. Genome Med 2017; 9:46. [PMID: 28539123 PMCID: PMC5442873 DOI: 10.1186/s13073-017-0434-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 05/03/2017] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Approximately 15% of primary colorectal cancers have DNA mismatch repair deficiency, causing a complex genome with thousands of small mutations-the microsatellite instability (MSI) phenotype. We investigated molecular heterogeneity and tumor immunogenicity in relation to clinical endpoints within this distinct subtype of colorectal cancers. METHODS A total of 333 primary MSI+ colorectal tumors from multiple cohorts were analyzed by multilevel genomics and computational modeling-including mutation profiling, clonality modeling, and neoantigen prediction in a subset of the tumors, as well as gene expression profiling for consensus molecular subtypes (CMS) and immune cell infiltration. RESULTS Novel, frequent frameshift mutations in four cancer-critical genes were identified by deep exome sequencing, including in CRTC1, BCL9, JAK1, and PTCH1. JAK1 loss-of-function mutations were validated with an overall frequency of 20% in Norwegian and British patients, and mutated tumors had up-regulation of transcriptional signatures associated with resistance to anti-PD-1 treatment. Clonality analyses revealed a high level of intra-tumor heterogeneity; however, this was not associated with disease progression. Among the MSI+ tumors, the total mutation load correlated with the number of predicted neoantigens (P = 4 × 10-5), but not with immune cell infiltration-this was dependent on the CMS class; MSI+ tumors in CMS1 were highly immunogenic compared to MSI+ tumors in CMS2-4. Both JAK1 mutations and CMS1 were favorable prognostic factors (hazard ratios 0.2 [0.05-0.9] and 0.4 [0.2-0.9], respectively, P = 0.03 and 0.02). CONCLUSIONS Multilevel genomic analyses of MSI+ colorectal cancer revealed molecular heterogeneity with clinical relevance, including tumor immunogenicity and a favorable patient outcome associated with JAK1 mutations and the transcriptomic subgroup CMS1, emphasizing the potential for prognostic stratification of this clinically important subtype. See related research highlight by Samstein and Chan 10.1186/s13073-017-0438-9.
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Affiliation(s)
- Anita Sveen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Bjarne Johannessen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Torstein Tengs
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Stine A. Danielsen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Ina A. Eilertsen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Guro E. Lind
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Kaja C. G. Berg
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Edward Leithe
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Leonardo A. Meza-Zepeda
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Department of Tumor Biology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Genomics Core Facility, Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
| | - Enric Domingo
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN UK
| | - Ola Myklebost
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Department of Tumor Biology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
| | - David Kerr
- Department of Oncology, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ UK
| | - Ian Tomlinson
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN UK
| | - Arild Nesbakken
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
- Department of Gastrointestinal Surgery, Oslo University Hospital, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Rolf I. Skotheim
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
| | - Ragnhild A. Lothe
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- K. G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Norwegian Cancer Genomics Consortium, Oslo University Hospital, P.O. Box 4953, Nydalen, NO-0424 Oslo Norway
- Centre for Cancer Biomedicine, Institute for Clinical Medicine, University of Oslo, P.O. Box 4950, Nydalen, NO-0424 Oslo Norway
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9
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Khan S. Potential role of Escherichia coli DNA mismatch repair proteins in colon cancer. Crit Rev Oncol Hematol 2015; 96:475-82. [PMID: 26014615 DOI: 10.1016/j.critrevonc.2015.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 03/15/2015] [Accepted: 05/05/2015] [Indexed: 02/07/2023] Open
Abstract
The epithelium of gastrointestinal tract organizes many innate defense systems against microbial intruders such as integrity of epithelial, rapid eviction of infected cells, quick turnover of epithelial cell, intrinsic immune responses and autophagy. However, Enteropathogenic Escherichia coli (EPEC) are equipped with well developed infectious tricks that evade the host defense systems and utilize the gastrointestinal epithelium as a multiplicative foothold. During multiplication on and within the epithelium, EPEC secrete various toxins that can weaken, usurp, and use many host cellular systems. However, the possible mechanisms of pathogenesis are still poorly elusive. Recent study reveals the existence of EPEC in colorectal cancer patients and their potential role in depletion of DNA mismatch repair (MMR) proteins of host cell in colonic cell lines. The EPEC colonised intracellularly in colon mucosa of colorectal carcinoma whereas extracellular strain was detected in mucosa of normal colon cells. Interestingly, alteration in MutS, MutL complexes and MUTYH of mammalian cells may be involved in development of CRC. These data propose that MMR of E. coli may be potential therapeutic targets and early detection biomarkers for CRC. This article reviews the potential role of E. coli MutS, MutL and MutY protein in CRC aetiology.
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Affiliation(s)
- Shahanavaj Khan
- Nanomedicine & Biotechnology Research Unit, Department of Pharmaceutics, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia.
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10
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Abstract
DNA mismatch repair (MMR) acts to repair mispaired bases resulting from misincorporation errors during DNA replication and also recognizes mispaired bases in recombination (HR) intermediates. Exonuclease 1 (Exo1) is a 5' → 3' exonuclease that participates in a number of DNA repair pathways. Exo1 was identified as an exonuclease that participates in Saccharomyces cerevisiae and human MMR where it functions to excise the daughter strand after mispair recognition, and additionally Exo1 functions in end resection during HR. However, Exo1 is not absolutely required for end resection during HR in vivo. Similarly, while Exo1 is required in MMR reactions that have been reconstituted in vitro, genetics studies have shown that it is not absolutely required for MMR in vivo suggesting the existence of Exo1-independent and Exo1-dependent MMR subpathways. Here, we review what is known about the Exo1-independent and Exo1-dependent subpathways, including studies of mutations in MMR genes that specifically disrupt either subpathway.
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Affiliation(s)
- Eva M Goellner
- Ludwig Institute for Cancer Research, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA
| | - Christopher D Putnam
- Ludwig Institute for Cancer Research, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA; Departments of Medicine, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA
| | - Richard D Kolodner
- Ludwig Institute for Cancer Research, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA; Departments of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA; Moores - UCSD Cancer Center, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA; Institute of Genomic Medicine, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA.
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Goellner EM, Smith CE, Campbell CS, Hombauer H, Desai A, Putnam CD, Kolodner RD. PCNA and Msh2-Msh6 activate an Mlh1-Pms1 endonuclease pathway required for Exo1-independent mismatch repair. Mol Cell 2014; 55:291-304. [PMID: 24981171 DOI: 10.1016/j.molcel.2014.04.034] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/09/2014] [Accepted: 04/28/2014] [Indexed: 11/17/2022]
Abstract
Genetic evidence has implicated multiple pathways in eukaryotic DNA mismatch repair (MMR) downstream of mispair recognition and Mlh1-Pms1 recruitment, including Exonuclease 1 (Exo1)-dependent and -independent pathways. We identified 14 mutations in POL30, which encodes PCNA in Saccharomyces cerevisiae, specific to Exo1-independent MMR. The mutations identified affected amino acids at three distinct sites on the PCNA structure. Multiple mutant PCNA proteins had defects either in trimerization and Msh2-Msh6 binding or in activation of the Mlh1-Pms1 endonuclease that initiates excision during MMR. The latter class of mutations led to hyperaccumulation of repair intermediate Mlh1-Pms1 foci and were enhanced by an msh6 mutation that disrupted the Msh2-Msh6 interaction with PCNA. These results reveal a central role for PCNA in the Exo1-independent MMR pathway and suggest that Msh2-Msh6 localizes PCNA to repair sites after mispair recognition to activate the Mlh1-Pms1 endonuclease for initiating Exo1-dependent repair or for driving progressive excision in Exo1-independent repair.
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Affiliation(s)
- Eva M Goellner
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Catherine E Smith
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Christopher S Campbell
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Hans Hombauer
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Arshad Desai
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Christopher D Putnam
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Richard D Kolodner
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Moores-UCSD Cancer Center, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Institute of Genomic Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
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12
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Srivatsan A, Bowen N, Kolodner RD. Mispair-specific recruitment of the Mlh1-Pms1 complex identifies repair substrates of the Saccharomyces cerevisiae Msh2-Msh3 complex. J Biol Chem 2014; 289:9352-64. [PMID: 24550389 DOI: 10.1074/jbc.m114.552190] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
DNA mismatch repair is initiated by either the Msh2-Msh6 or the Msh2-Msh3 mispair recognition heterodimer. Here we optimized the expression and purification of Saccharomyces cerevisiae Msh2-Msh3 and performed a comparative study of Msh2-Msh3 and Msh2-Msh6 for mispair binding, sliding clamp formation, and Mlh1-Pms1 recruitment. Msh2-Msh3 formed sliding clamps and recruited Mlh1-Pms1 on +1, +2, +3, and +4 insertion/deletions and CC, AA, and possibly GG mispairs, whereas Msh2-Msh6 formed mispair-dependent sliding clamps and recruited Mlh1-Pms1 on 7 of the 8 possible base:base mispairs, the +1 insertion/deletion mispair, and to a low level on the +2 but not the +3 or +4 insertion/deletion mispairs and not on the CC mispair. The mispair specificity of sliding clamp formation and Mlh1-Pms1 recruitment but not mispair binding alone correlated best with genetic data on the mispair specificity of Msh2-Msh3- and Msh2-Msh6-dependent mismatch repair in vivo. Analysis of an Msh2-Msh6/Msh3 chimeric protein and mutant Msh2-Msh3 complexes showed that the nucleotide binding domain and communicating regions but not the mispair binding domain of Msh2-Msh3 are responsible for the extremely rapid dissociation of Msh2-Msh3 sliding clamps from DNA relative to that seen for Msh2-Msh6, and that amino acid residues predicted to stabilize Msh2-Msh3 interactions with bent, strand-separated mispair-containing DNA are more critical for the recognition of small +1 insertion/deletions than larger +4 insertion/deletions.
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13
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Kanth VVR, Bhalsing S, Sasikala M, Rao GV, Pradeep R, Avanthi US, Reddy DN. Microsatellite instability and promoter hypermethylation in colorectal cancer in India. Tumour Biol 2014; 35:4347-55. [PMID: 24408015 DOI: 10.1007/s13277-013-1570-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 12/17/2013] [Indexed: 12/01/2022] Open
Abstract
Microsatellite instability (MSI) is an important factor in tumor development and is a hypermutable phenotype caused by the loss of DNA mismatch repair activity. It is important to identify tumors with microsatellite instability as the patients have a better prognosis and differ with response to chemotherapy. Limited data are available on the incidence of MSI in Indian colorectal cancers (CRCs). The objectives of this study were to identify the extent of MSI in Indian CRC patients below 50 years and to determine promoter methylation status of hMLH1 and hMSH2 in relation to MSI. A total of 450 patients were diagnosed with CRC, out of which 91 individuals were recruited as per Bethesda guidelines and were tested for instability by the NCI-recommended Bethesda panel (BAT25, BAT26, D2S123, D5S346, and D17S2720) using labeled primers. The fragments were separated and analyzed on a Beckman GeXP sequencer. Promoter methylation status was determined by restriction enzyme digestion and PCR. MSI (high and low) was seen in 48.4% (44/91) of CRC patients, out of which microsatellite instability-high (MSI-H) was detected in 13.2% (12/91) and microsatellite instability-low (MSI-L) in 35.2% (32/91) and the rest were microsatellite stable (MSS), 51.6% (47/91). Majority of the MSI-H tumors were adenocarcinomas (10/12), in the rectum (8/12), and moderately or poorly differentiated (12/12). Promoter hypermethylation was seen in 75% of the MSI-H, 56.24% of MSI-L, and only 23.4% of MSS individuals. MSI (high and low) was associated with 48.4% of CRC patients, and a significantly higher proportion of promoter hypermethylation of hMLH1 and hMSH2 genes was associated with instable tumors.
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14
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Promoter methylation and immunohistochemical expression of hMLH1 and hMSH2 in sporadic colorectal cancer: a study from India. Tumour Biol 2013; 35:3679-87. [PMID: 24317816 DOI: 10.1007/s13277-013-1487-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Accepted: 11/27/2013] [Indexed: 12/29/2022] Open
Abstract
To determine the etiological factors of human colorectal cancer (CRC) we assessed the frequency and prognostic significance of hMLH1 and hMSH2 genes in conjunction with hMLH1 and hMSH2 protein expression in 30 Indian CRC patients. The protein expression and promoter methylation of hMLH1 and hMSH2; Mismatch Repair genes (MMR) were analyzed by immunohistochemistry and methylation-specific PCR (MSP), respectively. A loss of hMLH1 expression was recognized in 4(13.3%) and loss of hMSH2 expression was recognized in 2(6.6%) of 30 CRC cases whereas 50% tumors showed reduced expression of hMLH1 and 33.3% showed reduced expression of hMSH2 protein. One tumor showed a loss of both hMLH1 and hMSH2 expression. Normal nuclear staining pattern of hMLH1 and hMSH2 was observed in almost all the adjoining and normal mucosa. Promoter hypermethylation of the hMLH1 gene was detected in 15 of 30 CRC cases (50%) and of hMSH2 gene was only in 3 of 30 CRC cases (10%). No promoter methylation of hMLH1 and hMSH2 genes was observed in adjoining and normal mucosa. Combination of methylation of hMLH1 and hMSH2 gene was observed in two tumors (6.6%). A significant correlation between histological grade of the tumor, methylation and expression of hMLH1 gene (p < 0.05) was observed. Normal expression of hMLH1 and hMSH2 was seen in all of the unmethylated tumors (100%). Nuclear staining and promoter methylation of hMLH1 and hMSH2 did not significantly influence survival. hMLH1 methylation was common and was significantly correlated with loss of hMLH1 protein expression. In contrast, hMSH2 methylation was infrequent. These findings suggest that the inactivation of MMR gene expression probably via hypermethylation may lead to inactivation of their functions which finally leads to tumor aggressiveness and the immunostaining of hMLH1 protein can be used as a prognostic factor for determining the grade of the tumor.
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15
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Smith CE, Mendillo ML, Bowen N, Hombauer H, Campbell CS, Desai A, Putnam CD, Kolodner RD. Dominant mutations in S. cerevisiae PMS1 identify the Mlh1-Pms1 endonuclease active site and an exonuclease 1-independent mismatch repair pathway. PLoS Genet 2013; 9:e1003869. [PMID: 24204293 PMCID: PMC3814310 DOI: 10.1371/journal.pgen.1003869] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/25/2013] [Indexed: 12/28/2022] Open
Abstract
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. 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. In addition to these genes, various DNA replication factors and the excision factor EXO1 function in the repair of damaged DNA by the MMR pathway. Although EXO1 is considered to be the major repair nuclease functioning in mismatch repair, the relatively low mutation rates caused by an exo1 deletion suggest otherwise. Here we used genetics, microscopy and protein biochemistry to analyze the model organism Saccharomyces cerevisiae to further characterize a poorly understood mismatch repair pathway that functions in the absence of EXO1 that is highly dependent on the Mlh1-Pms1 complex. Surprisingly, we found that the highly conserved metal binding site that is critical for the endonuclease activity of the Mlh1-Pms1 heterodimer is required for MMR in the absence of Exo1 to a much greater extent than in the presence of Exo1. Thus, this work establishes that there are at least two different polynucleotide excision pathways that function in MMR.
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Affiliation(s)
- Catherine E Smith
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
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16
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Donigan KA, Sun KW, Nemec AA, Murphy DL, Cong X, Northrup V, Zelterman D, Sweasy JB. Human POLB gene is mutated in high percentage of colorectal tumors. J Biol Chem 2012; 287:23830-9. [PMID: 22577134 PMCID: PMC3390656 DOI: 10.1074/jbc.m111.324947] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 05/10/2012] [Indexed: 12/11/2022] Open
Abstract
Previous small scale sequencing studies have indicated that DNA polymerase β (pol β) variants are present on average in 30% of human tumors of varying tissue origin. Many of these variants have been shown to have aberrant enzyme function in vitro and to induce cellular transformation and/or genomic instability in vivo, suggesting that their presence is associated with tumorigenesis or its progression. In this study, the human POLB gene was sequenced in a collection of 134 human colorectal tumors and was found to contain coding region mutations in 40% of the samples. The variants map to many different sites of the pol β protein and are not clustered. Many variants are nonsynonymous amino acid substitutions predicted to affect enzyme function. A subset of these variants was found to have reduced enzyme activity in vitro and failed to fully rescue pol β-deficient cells from methylmethane sulfonate-induced cytotoxicity. Tumors harboring variants with reduced enzyme activity may have compromised base excision repair function, as evidenced by our methylmethane sulfonate sensitivity studies. Such compromised base excision repair may drive tumorigenesis by leading to an increase in mutagenesis or genomic instability.
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Affiliation(s)
| | - Ka-wai Sun
- From the Departments of Therapeutic Radiology and Genetics and
| | | | - Drew L. Murphy
- From the Departments of Therapeutic Radiology and Genetics and
| | - Xiangyu Cong
- Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Veronika Northrup
- Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Daniel Zelterman
- Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Joann B. Sweasy
- From the Departments of Therapeutic Radiology and Genetics and
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17
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Zhang R, Qin W, Xu GL, Zeng FF, Li CX. A meta-analysis of the prevalence of somatic mutations in the hMLH1 and hMSH2 genes in colorectal cancer. Colorectal Dis 2012; 14:e80-9. [PMID: 21988782 DOI: 10.1111/j.1463-1318.2011.02858.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
AIM The study aimed to understand better the somatic mutations in the human MutL Homolog 1 (hMLH1) and human MutS Homolog 2 (hMSH2) genes in colorectal cancer (CRC) and to investigate the differences derived from ethnicity, family history, detection method and microsatellite instability (MSI). METHOD The terms 'hMSH2' or 'hMLH1' and 'colorectal cancer' 'colorectal carcinoma' or 'colorectal tumour' were searched in the PubMed, Springer, Lippincott, Williams & Wilkins and HighWire Press databases for the publication period December 1993 to September 2010. The Comprehensive Meta Analysis V2 software (Biostat Inc.) was used to explore the prevalence and 95% confidence intervals. RESULTS The prevalence of somatic mutations in the hMLH1 and hMSH2 genes in CRC was 0.15 (95% CI 0.10-0.22) and 0.10 (95% CI 0.07-0.16), respectively. A higher prevalence of somatic mutations in hMSH2 was found in hereditary non-polyposis CRC than in sporadic CRC: 0.36 (95% CI 0.14-0.67) and 0.10 (95% CI 0.07-0.13) respectively. In addition, a higher prevalence of somatic mutations in the hMLH1 gene was observed relative to hMSH2 in the European group. The prevalence was higher in the high-level instability (MSI-H) group than in both the low-level instability (MSI-L) and the microsatellite stable (MSS) groups. CONCLUSION Somatic mutations in the hMLH1 and hMSH2 genes play a vital role in CRC and a high prevalence was found in this meta-analysis. Furthermore, more studies are needed which focus on somatic mutations in the American population and in patients with MSI-L and MSS.
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Affiliation(s)
- R Zhang
- State Key Laboratory of Oncology in South China, Cancer Centre, Guangzhou, China
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18
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Tug E, Balaban YH, Sahin EK. Mapping of microsatellite instability in endoscopic normal colon. Genet Test Mol Biomarkers 2012; 16:388-95. [PMID: 22224632 DOI: 10.1089/gtmb.2011.0219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Genomic instability in colorectal cancer (CRC) occurs as either microsatellite instability (MSI) or chromosomal instability. The present study was aimed at examining the MSI for the MLH1 and MSH2 genes in normal colon and polyps, if detected. Four segments of the colon were sampled in 102 subjects during colonoscopy. DNA samples were analyzed for the MSI status according to the Bethesda consensus panel. Family history of any type of cancer or for colon cancer was present in 44.8% and 9.4% of the individuals, respectively. Forty-eight percent of individuals were microsatellite stable for all five markers at all locations, 20% had low MSI status (MSI-L), and 32% had high MSI status (MSI-H). The frequencies of MSI markers differed significantly from each other (p=0.003). The most frequent positive marker was D17S250. This is the first study which revealed that MSI is present in endoscopically normal-looking colon of normal individuals and, more frequently, in individuals with family histories of CRC. The detection of very early-stage CRC is possible by MSI analysis of DNA mismatch repair genes in colon tissues. This study has revealed crucial information for the use of molecular tests in CRC screening, such as high frequencies of MSI in endoscopically normal colon, which might cause false positivity.
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Affiliation(s)
- Esra Tug
- Department of Medical Genetics, Faculty of Medicine, Gazi University, Ankara, Turkey.
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19
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Chintharlapalli S, Papineni S, Lei P, Pathi S, Safe S. Betulinic acid inhibits colon cancer cell and tumor growth and induces proteasome-dependent and -independent downregulation of specificity proteins (Sp) transcription factors. BMC Cancer 2011; 11:371. [PMID: 21864401 PMCID: PMC3170653 DOI: 10.1186/1471-2407-11-371] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 08/24/2011] [Indexed: 12/31/2022] Open
Abstract
Background Betulinic acid (BA) inhibits growth of several cancer cell lines and tumors and the effects of BA have been attributed to its mitochondriotoxicity and inhibition of multiple pro-oncogenic factors. Previous studies show that BA induces proteasome-dependent degradation of specificity protein (Sp) transcription factors Sp1, Sp3 and Sp4 in prostate cancer cells and this study focused on the mechanism of action of BA in colon cancer cells. Methods The effects of BA on colon cancer cell proliferation and apoptosis and tumor growth in vivo were determined using standardized assays. The effects of BA on Sp proteins and Sp-regulated gene products were analyzed by western blots, and real time PCR was used to determine microRNA-27a (miR-27a) and ZBTB10 mRNA expression. Results BA inhibited growth and induced apoptosis in RKO and SW480 colon cancer cells and inhibited tumor growth in athymic nude mice bearing RKO cells as xenograft. BA also decreased expression of Sp1, Sp3 and Sp4 transcription factors which are overexpressed in colon cancer cells and decreased levels of several Sp-regulated genes including survivin, vascular endothelial growth factor, p65 sub-unit of NFκB, epidermal growth factor receptor, cyclin D1, and pituitary tumor transforming gene-1. The mechanism of action of BA was dependent on cell context, since BA induced proteasome-dependent and proteasome-independent downregulation of Sp1, Sp3 and Sp4 in SW480 and RKO cells, respectively. In RKO cells, the mechanism of BA-induced repression of Sp1, Sp3 and Sp4 was due to induction of reactive oxygen species (ROS), ROS-mediated repression of microRNA-27a, and induction of the Sp repressor gene ZBTB10. Conclusions These results suggest that the anticancer activity of BA in colon cancer cells is due, in part, to downregulation of Sp1, Sp3 and Sp4 transcription factors; however, the mechanism of this response is cell context-dependent.
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Affiliation(s)
- Sudhakar Chintharlapalli
- Department of Veterinary Physiology & Pharmacology, Texas A&M University, College Station, TX 77843, USA
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20
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Perrett CM, Harwood CA, McGregor JM, Warwick J, Cerio R, Karran P. Expression of DNA mismatch repair proteins and MSH2 polymorphisms in nonmelanoma skin cancers of organ transplant recipients. Br J Dermatol 2010; 162:732-42. [PMID: 19818066 DOI: 10.1111/j.1365-2133.2009.09550.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Organ transplant recipients (OTRs) have an increased risk of skin cancer. Treatment with azathioprine, commonly used in post-transplant immunosuppressive regimens, results in incorporation of 6-thioguanine (6-TG) into DNA. Mismatch repair (MMR)-defective cells are resistant to killing by 6-TG. Azathioprine exposure confers a survival advantage on MMR-defective cells, which are hypermutable and may therefore contribute to azathioprine-related nonmelanoma skin cancer, a phenomenon we have previously demonstrated in transplant-associated sebaceous carcinomas. The MSH2 protein is an important component of DNA MMR. The -6 exon 13 T>C MSH2 polymorphism is associated with impaired MMR, drug resistance and certain cancers. OBJECTIVES To investigate (i) whether loss of MMR protein expression and microsatellite instability are over-represented in squamous cell carcinomas (SCCs) from OTRs on azathioprine compared with SCCs from immunocompetent patients, and (ii) whether the MSH2 -6 exon 13 polymorphism is over-represented in OTRs with skin cancer on azathioprine. METHODS (i) Immunohistochemical staining was used to assess expression of the MMR proteins MSH2 and MLH1 in cutaneous SCCs from OTRs on azathioprine and from immunocompetent patients. (ii) Blood samples from OTRs on azathioprine with and without skin cancer were genotyped for the -6 exon 13 MSH2 polymorphism. RESULTS (i) MSH2 and MLH1 protein expression was not altered in SCCs from OTRs on azathioprine and there was no difference in expression between SCCs from OTRs and immunocompetent patients. (ii) There was no association between MSH2 polymorphism genotype frequency and OTR skin cancer status. CONCLUSIONS Despite previous findings in transplant-associated sebaceous carcinomas, defective MMR and the -6 exon 13 MSH2 polymorphism are unlikely to play a significant role in the development of SCC in OTRs on azathioprine.
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Affiliation(s)
- C M Perrett
- Centre for Cutaneous Research and Department of Dermatology, Institute of Cell and Molecular Science, Barts and The London School of Medicine and Dentistry, Queen Mary, University of London, 4 Newark Street, London E1 2AT, U.K.
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21
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Aissi-Ben Moussa S, Moussa A, Lovecchio T, Kourda N, Najjar T, Ben Jilani S, El Gaaied A, Porchet N, Manai M, Buisine MP. Identification and characterization of a novel MLH1 genomic rearrangement as the cause of HNPCC in a Tunisian family: evidence for a homologous Alu-mediated recombination. Fam Cancer 2008; 8:119-26. [PMID: 18792805 DOI: 10.1007/s10689-008-9215-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Accepted: 09/02/2008] [Indexed: 12/15/2022]
Abstract
High rates of early colorectal cancers are observed in Tunisia suggesting high genetic susceptibility. Nevertheless, up to now no molecular studies have been performed. Hereditary nonpolyposis colorectal cancer (HNPCC) is the most frequent cause of inherited colorectal cancer. It is caused by constitutional mutations in the DNA mismatch repair (MMR) genes. Here, we investigated a Tunisian family highly suspected of hereditary nonpolyposis colorectal cancer (HNPCC). Six patients were diagnosed with a colorectal or an endometrial cancer at an early age, including one young female who developed a colorectal cancer at 22 years and we tested for germline mutations in MMR genes. MMR genes were tested for rearrangements by MLPA (MLH1, MSH2) and the presence of point mutations by sequencing (MLH1, MSH2, MSH6). Moreover, tumors were analyzed for microsatellite instability and expression of MMR proteins, as well as for somatic rearrangements in MLH1 and MSH2 by MLPA. MMR gene analysis by MLPA revealed the presence of a large deletion in MLH1 removing exon 6. Sequence analysis of the breakpoint region showed that this rearrangement resulted from a homologous unequal recombination mediated by a repetitive Alu sequence. Moreover, tumors harbored biallelic deletion of MLH1 exon 6 and loss of heterozygosity at MLH1 intragenic markers, suggesting duplication of the rearranged allele in the tumor. This germline MLH1 rearrangement was associated to a severe phenotype in this family. This is the first report of a molecular analysis in a Tunisian family with HNPCC.
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Affiliation(s)
- Sana Aissi-Ben Moussa
- Laboratoire de Biochimie et Biologie Moléculaire, Faculté des Sciences de Tunis, Tunis, Tunisia
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Chang IY, Jin M, Yoon SP, Youn CK, Yoon Y, Moon SP, Hyun JW, Jun JY, You HJ. Senescence-dependent MutS alpha dysfunction attenuates mismatch repair. Mol Cancer Res 2008; 6:978-89. [PMID: 18567801 DOI: 10.1158/1541-7786.mcr-07-0380] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
DNA damage and mutations in the genome increase with age. To determine the potential mechanisms of senescence-dependent increases in genomic instability, we analyzed DNA mismatch repair (MMR) efficiency in young and senescent human colonic fibroblast and human embryonic lung fibroblast. It was found that MMR activity is significantly reduced in senescent cells. Western blot and immunohistochemistry analysis revealed that hMSH2 and MSH6 protein (MutS alpha complex), which is a known key component in the MMR pathway, is markedly down-regulated in senescent cells. Moreover, the addition of purified MutS alpha to extracts from senescent cells led to the restoration of MMR activity. Semiquantitative reverse transcription-PCR analysis exhibited that MSH2 mRNA level is reduced in senescent cells. In addition, a decrease in E2F transcriptional activity in senescent cells was found to be crucial for MSH2 suppression. E2F1 small interfering RNA expression reduced hMSH2 expression and MMR activity in young human primary fibroblast cells. Importantly, expression of E2F1 in quiescent cells restored the MSH2 expression as well as MMR activity, whereas E2F1-infected senescent cells exhibited no restoration of MSH2 expression and MMR activity. These results indicate that the suppression of E2F1 transcriptional activity in senescent cells lead to stable repression of MSH2, followed by a induction of MutS alpha dysfunction, which results in a reduced cellular MMR capacity in senescent cells.
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Affiliation(s)
- In-Youb Chang
- Korean DNA Repair Research Center, Republic of Korea (South Korea)
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23
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Pinto M, Wu Y, Mensink RGJ, Cirnes L, Seruca R, Hofstra RMW. Somatic mutations in mismatch repair genes in sporadic gastric carcinomas are not a cause but a consequence of the mutator phenotype. ACTA ACUST UNITED AC 2008; 180:110-4. [PMID: 18206535 DOI: 10.1016/j.cancergencyto.2007.09.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 09/26/2007] [Accepted: 09/26/2007] [Indexed: 12/20/2022]
Abstract
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, although somatic mutations in MMR genes have been described. We aimed to investigate which MMR defects are present in SGC. Twenty-nine MSI-H SGC investigated previously for MLH1 promoter hypermethylation were screened for somatic mutations in MLH1, MSH2, MSH6, MLH3, and MBD4 by denaturing gradient gel electrophoresis and sequencing. Five truncating mutations (three in MSH6, one in MLH3, and one in MBD4) and one missense mutation (MLH1) were identified. Of these, three truncating mutations were in MSI-H cases that lack MLH1 hypermethylation. As all truncating mutations were found in the coding poly-A tracts, it seems likely that they result from the MSI phenotype rather than cause it. In summary, somatic mutations in MMR genes are rare in SGC and do not explain the development of these tumors reflecting, rather than causing, the mutator phenotype. Other MMR genes are probably involved in MSI-H gastric cancer without MLH1 hypermethylation.
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Affiliation(s)
- Mafalda Pinto
- IPATIMUP- Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Rua Roberto Frias, 4200-465 Porto, Portugal.
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Naqvi RA, Hussain A, Deo SSV, Kukreti H, Chauhan M, Sarin R, Saxena A, Asim M, Shukla NK, Husain SA, Pasha ST, Basir SF. Hypermethylation analysis of mismatch repair genes (hmlh1 and hmsh2) in locally advanced breast cancers in Indian women. Hum Pathol 2008; 39:672-80. [PMID: 18329696 DOI: 10.1016/j.humpath.2007.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2007] [Revised: 09/11/2007] [Accepted: 09/14/2007] [Indexed: 12/31/2022]
Abstract
Alterations in protooncogenes and tumor-suppressor genes at the DNA and/or protein level, which indicate the biological properties of individual breast cancers, led us to design a study encompassing the dilemma of "epigenetic silencing-driven genomic instabilities." In this study, we analyzed the promoter methylation of potent mismatch repair genes (hmlh1 and hmsh2) for the first time in 232 Indian patients with primary breast cancer (using methylation-specific polymerase chain reaction and expressional analysis). The study evaluates the gamut of epigenetic aberrations as well as genomic instabilities (microsatellite instabilities and loss of heterozygosity) and includes analysis of BAT-25, BAT-26, D2S123, D5S346, and D17S250. We observed hypermethylation of the hmlh1 gene in 43.5% of patients with primary breast cancer, of whom 66.9% had locally advanced breast cancer (stage IIIA, IIIB, and IIIC) (P < .0001). Similarly, we also found hypermethylation of the hmsh 2 gene in 16% of primary breast cancer cases. Of these patients, 21.3% had locally advanced breast cancer (P = . 01). To determine the effect of methylation, we also performed expressional studies using reverse transcriptase polymerase chain reaction and Northern blotting, but we were unable to get any significant expression in the presence of hypermethylation of either gene (hmlh1 and hmsh2). Interestingly, statistical analysis revealed that hypermethylation of the hmlh1 gene is one of the peculiar attributes of locally advanced breast cancer. In addition, this study indicates that for more sensitive stage-specific diagnosis or prognosis, both methylation of promoter and expression studies must be considered in the analyses in a reproducible manner. Therefore, pinpointing the methylation fingerprints (5'CpG island methylation) of potent DNA repairing genes not only shows the specific attributes of locally advanced breast cancer but also provides important insight into the mode of therapy to be used by clinical oncologists.
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Affiliation(s)
- Raza Ali Naqvi
- Department of Biosciences, Jamia Millia Islamia, New Delhi 110025, India
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Oliart S, Martínez-Santos C, Moreno-Azcoita M, Cerquella C, Nejda N, Daimiel L, Iglesias D, Fernández-Peralta AM, González-Aguilera JJ. Do MSI-L Sporadic Colorectal Tumors Develop Through “Mild Mutator Pathway”? Am J Clin Oncol 2006; 29:364-70. [PMID: 16891863 DOI: 10.1097/01.coc.0000221428.35366.cb] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND The mutator pathway implied in the development of colorectal cancer (CRC) is characterized by microsatellite instability (MSI). MSI tumors can be subdivided according to the level of instability: MSI-H (high), MSI-L (low) or stable MSS. MSI-H CRC displays a well described distinct phenotype, but the true biologic significance of MSI-L is still uncertain. The objective of this study was to further clarify if the MSI-L phenotype could reflect a distinct pathway of tumor development with a different clinical behavior. METHODS We analyzed the clinicopathological and genetic variables of 156 patients with sporadic CRC in relation with the level of MSI of the tumors. RESULTS We have found that MSI-L tumors are someway in the middle of MSI-H and MSS CRC, as they share some features with each of the other 2 subgroups: left side location, lower incidence of LOH at MSH2 as MSS and Dukes B (stage II TNM) like MSI-H. Moreover, MSI-L tumors show higher incidence of KRAS mutations. CONCLUSION We believe that MSI-L tumors could be considered a distinct phenotype that develops through a "mild mutator pathway."
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Affiliation(s)
- Soledad Oliart
- Servicio de Cirugía, Hospital Central de la Cruz Roja San José y Santa Adela, Reina Victoria, Madrid, Spain
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Jung CY, Choi JE, Park JM, Chae MH, Kang HG, Kim KM, Lee SJ, Lee WK, Kam S, Cha SI, Kim CH, Han SB, Jung TH, Jeon SH, Park JY. Polymorphisms in the hMSH2 Gene and the Risk of Primary Lung Cancer. Cancer Epidemiol Biomarkers Prev 2006; 15:762-8. [PMID: 16614121 DOI: 10.1158/1055-9965.epi-05-0834] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Polymorphisms in the DNA repair genes may be associated with differences in the capacity to repair DNA damage, and so this can influence an individual's susceptibility to lung cancer. To test this hypothesis, we investigated the association of hMSH2 -118T>C, IVS1+9G>C, IVS10+12A>G, and IVS12-6T>C genotypes and their haplotypes with the risk of lung cancer in a Korean population. The hMSH2 genotypes were determined in 432 lung cancer patients and in 432 healthy controls who were frequency matched for age and gender. The hMSH2 haplotypes were estimated based on a Bayesian algorithm using the Phase program. The presence of at least one IVS10+12G allele was associated with a significantly decreased risk of adenocarcinoma, as compared with the IVS10+12AA genotype [adjusted odds ratio (OR), 0.59; 95% confidence interval (95% CI), 0.40-0.88; P = 0.01], and the presence of at least one IVS12-6C allele was associated with a significantly increased risk of adenocarcinoma, as compared with the IVS12-6TT genotype (adjusted OR, 1.52; 95% CI, 1.02-2.27; P = 0.04). Consistent with the results of the genotyping analysis, the TGGT haplotype with no risk allele was associated with a significantly decreased risk of adenocarcinoma, as compared with the TCAC haplotype with two risk allele [i.e., IVS10+12A and IVS12-6C allele; adjusted OR, 0.49; 95% CI, 0.30-0.78; P = 0.003 and P(c) (Bonferroni corrected P value) = 0.012]. The effect of the hMSH2 haplotypes on the risk of adenocarcinoma was statistically significant in the never smokers and younger individuals (adjusted OR, 0.45; 95% CI, 0.27-0.75; P = 0.002 and P(c) = 0.004; and adjusted OR, 0.44; 95% CI, 0.23-0.85; P = 0.014 and P(c) = 0.028, respectively) but not in the ever-smokers and older individuals. These results suggest that the hMSH2 polymorphisms and their haplotypes may be an important genetic determinant of adenocarcinoma of the lung, particularly in never smokers.
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Affiliation(s)
- Chi Young Jung
- Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Korea
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Woods MO, Hyde AJ, Curtis FK, Stuckless S, Green JS, Pollett AF, Robb JD, Green RC, Croitoru ME, Careen A, Chaulk JAW, Jegathesan J, McLaughlin JR, Gallinger SS, Younghusband HB, Bapat BV, Parfrey PS. High frequency of hereditary colorectal cancer in Newfoundland likely involves novel susceptibility genes. Clin Cancer Res 2006; 11:6853-61. [PMID: 16203774 DOI: 10.1158/1078-0432.ccr-05-0726] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Newfoundland has one of the highest rates of colorectal cancer in North America. The most common hereditary form of colorectal cancer is hereditary nonpolyposis colorectal cancer caused by mutations in genes involved in mismatch repair. Our purpose was to determine the proportion of hereditary colorectal cancer and to determine the genetic basis of disease in both population and clinically referred cohorts from Newfoundland. EXPERIMENTAL DESIGN Seventy-eight colorectal cancer patients were accrued over a 2-year period from the Avalon Peninsula of Newfoundland. We also examined 31 hereditary nonpolyposis colorectal cancer-like families, which had been referred to the Provincial Medical Genetics Program. Tumors from probands were tested by immunohistochemistry for deficiencies in MLH1, MSH2, and MSH6 proteins and tested for DNA microsatellite instability. Mutation analyses of MLH1, MSH2, and MSH6 were undertaken by direct sequencing and an assay to detect deletions, amplifications, and rearrangements in MSH2 and MLH1. RESULTS We identified eight population-based families that fulfill the Amsterdam I or II criteria, 4 (50%) of which seem to have hereditary cancer not attributable to the most commonly mutated mismatch repair genes. In addition, in 16 of 21 (76%) referred families fulfilling Amsterdam I or II criteria, no mutations were found in the three most commonly altered mismatch repair genes, and tumor analyses corroborated these findings. CONCLUSIONS It seems that strong and novel genetic causes of hereditary colorectal cancer are responsible for a high proportion of colorectal cancer in this population. Conditions are suitable for the identification of these genes by linkage studies of large Newfoundland cancer families.
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Affiliation(s)
- Michael O Woods
- Discipline of Genetics, Department of Genetics, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
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Abstract
The observation that mutations in tumor suppressor genes can have haploinsufficient, as well as gain of function and dominant negative, phenotypes has caused a reevaluation of the 'two-hit' model of tumor suppressor inactivation. Here we examine the history of haploinsufficiency and tumor suppressors in order to understand the origin of the 'two-hit' dogma. The two-hit model of tumor suppressor gene inactivation was derived from mathematical modeling of cancer incidence. Subsequent interpretations implied that tumor suppressors were recessive, requiring mutations in both alleles. This model has provided a useful conceptual framework for three decades of research on the genetics and biology of tumor suppressor genes. Recently it has become clear that mutations in tumor suppressor genes are not always completely recessive. Haploinsufficiency occurs when one allele is insufficient to confer the full functionality produced from two wild-type alleles. Haploinsufficiency, however, is not an absolute property. It can be partial or complete and can vary depending on tissue type, other epistatic interactions, and environmental factors. In addition to simple quantitative differences (one allele versus two alleles), gene mutations can have qualitative differences, creating gain of function or dominant negative effects that can be difficult to distinguish from dosage-dependence. Like mutations in many other genes, tumor suppressor gene mutations can be haploinsufficient, dominant negative or gain of function in addition to recessive. Thus, under certain circumstances, one hit may be sufficient for inactivation. In addition, the phenotypic penetrance of these mutations can vary depending on the nature of the mutation itself, the genetic background, the tissue type, environmental factors and other variables. Incorporating these new findings into existing models of the clonal evolution will be a challenge for the future.
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Affiliation(s)
- Shannon R Payne
- Fred Hutchinson Cancer Research Center, Seattle, WA 90109, USA
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29
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Abstract
Colorectal cancer is one of the major causes of cancer deaths in both men and women. It is estimated that approximately 5% to 10% of patients with colorectal cancer have an inherited germline mutation that predisposes them to cancer. Clinically, hereditary colorectal cancer syndromes can be divided into those associated with colonic polyposis (familial adenomatous polyposis, attenuated familial adenomatous polyposis, and MYH-associated polyposis) and those not associated with colonic polyposis (hereditary nonpolyposis colon cancer). Treatment options for these patients include multiple aggressive screening regimens, chemopreventive medications, and prophylactic surgery. Selection of the appropriate management approach is best made using information obtained from the patient's clinical examination, the family medical history, and genetic evaluation. Compliance is improved when patients completely understand their disease and participate fully in the formulation of the treatment plan. Although not proved, it seems reasonable that this approach may prevent the poor outcomes so frequently associated with inherited cancer syndromes.
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Affiliation(s)
- C Neal Ellis
- Department of Surgery, University of South Alabama, Mobile, AL 36617-2293, USA.
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Bjørheim J, Ekstrøm PO. Review of denaturant capillary electrophoresis in DNA variation analysis. Electrophoresis 2005; 26:2520-30. [PMID: 15934053 DOI: 10.1002/elps.200410403] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Analyses of germline and somatic single-nucleotide DNA variations are important in both population genetics research and clinical practice. Reliable and inexpensive methods that are flexible and designed for automation are required for these analyses. Present day DNA sequencing technology is too expensive for testing all 22-25 000 human genes in populations genetics studies or in scanning large numbers of tumors for novel mutations. Denaturant capillary electrophoresis (DCE) has the potential to meet the need for large-scale analysis of DNA variants. Several different analyses can be performed by DCE, including mutation analysis, single-nucleotide polymorphism (SNP) discovery in individual and pooled samples, detection of allelic imbalance, and determination of microhaplotypes. Here we review the theoretical background of the method, its sensitivity, specificity, detection limit, throughput, and repeatability in the light of current literature in the field.
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Affiliation(s)
- Jens Bjørheim
- Section for Immunotherapy, Department of Immunology, Institute for Cancer Research, University of Oslo, Oslo, Norway
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31
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Pickett HA, Baird DM, Hoff-Olsen P, Meling GI, Rognum TO, Shaw J, West KP, Royle NJ. Telomere instability detected in sporadic colon cancers, some showing mutations in a mismatch repair gene. Oncogene 2004; 23:3434-43. [PMID: 15048084 DOI: 10.1038/sj.onc.1207477] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Human telomeres are essential for genome stability and are composed of long simple tandem repeat arrays (STRs), comprising the consensus TTAGGG repeat interspersed, at the proximal end, with sequence-variant repeats. While the dynamics of telomere attrition through incomplete replication has been studied extensively, the effects on telomeres of error-prone DNA repair processes, known to affect other STRs, are poorly understood. We have compared the TTAGGG and sequence-variant interspersion patterns in the proximal 720 bp of telomeres in colon cancer and normal DNA samples. The frequency of telomere mutations was 5.8% per allele in a randomly collected panel of sporadic colon cancers, showing that telomere mutations occur in vivo. The mutation frequency rose to 18.6% per allele in sporadic tumours that exhibit instability at the polyA tract in the TGFbetaRII gene and to 35% per allele in tumours with somatic mutations in the hMSH2 gene. The majority of the characterized mutations resulted in the loss of one or a few repeats. If the mutation spectrum and frequency described here is reiterated in the rest of the array, there is the potential for extensive telomere destabilization especially in mismatch repair-defective cells. This may in turn lead to a greater requirement for telomere length maintenance earlier in tumourigenesis.
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Affiliation(s)
- Hilda Amelia Pickett
- Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK
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32
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Cederquist K, Emanuelsson M, Göransson I, Holinski-Feder E, Müller-Koch Y, Golovleva I, Grönberg H. Mutation analysis of the MLH1, MSH2 and MSH6 genes in patients with double primary cancers of the colorectum and the endometrium: a population-based study in northern Sweden. Int J Cancer 2004; 109:370-6. [PMID: 14961575 DOI: 10.1002/ijc.11718] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disorder that predisposes to predominantly colorectal and endometrial cancers due to germline mutations in DNA mismatch repair genes, mainly MLH1, MSH2 and in families with excess endometrial cancer also MSH6. In this population-based study, we analysed the mutation spectrum of the MLH1, MSH2 and MSH6 genes in a cohort of patients with microsatellite unstable double primary tumours of the colorectum and the endometrium by PCR, DHPLC and sequencing. Fourteen of the 23 patients (61%) had sequence variants in MLH1, MSH2 or MSH6 that likely affect the protein function. A majority (10/14) of the mutations was found among probands diagnosed before age 50. Five of the mutations (36%) were located in MLH1, 3 (21%) in MSH2 and 6 (43%) in MSH6. MSH6 seem to have larger impact in our population than in other populations, due to a founder effect since all of the MSH6 families originate from the same geographical area. MSH6 mutation carriers have later age of onset of both colorectal cancer (62 vs. 51 years) and endometrial cancer (58 vs. 48 years) and a larger proportion of endometrial cancer than MLH1 or MSH2 mutation carriers. We can conclude that patients with microsatellite unstable double primary cancers of the colorectum and the endometrium have a very high risk of carrying a mutation not only in MLH1 or MSH2 but also in MSH6, especially if they get their first cancer diagnosis before the age of 50.
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Affiliation(s)
- Kristina Cederquist
- Unit of Medical and Clinical Genetics, Department of Medical Biosciences, Umeå University, Sweden.
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Zhang QX, Ding Y, Le XP, Du P. Studies on microsatellite instability in p16 gene and expression of hMSH2 mRNA in human gastric cancer tissues. World J Gastroenterol 2003; 9:437-41. [PMID: 12632492 PMCID: PMC4621556 DOI: 10.3748/wjg.v9.i3.437] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To detect the loss of heterozygosity (LOH) frequency of microsatellite sites D9s171, D9s1604 of p16 gene and expression of hMSH2 mRNA in various differentiated types of gastric cancer, adjacent cancer tissues and normal gastric mucosa.
METHODS: LOH was detected by polymerase chain reaction (PCR)-denaturing polyacrylamide gel electrophoresis-silver staining. The expression of hMSH2 mRNA was examined with in situ hybridization.
RESULTS: The frequency rate of LOH was significantly higher in gastric cancers than that in adjacent cancer tissues (P = 0.032). No significant difference was noted among various differentiated types and various clinical stages of gastric cancers. The significantly reduced expression of hMSH2 mRNA positive signal cells exhibited in gastric cancers, in comparison with that in the adjacent cancer tissues and normal gastric mucosa, respectively (P = 0.001). No significant difference was noted among various clinical stages of gastric cancers (P > 0.05). The difference of positive signal cells in poorly differentiated cancers and those in well and moderately differentiated cancers were significant (P < 0.001).
CONCLUSION: The frequencies of LOH in two microsatellite sites, D9s171 and D9s1604, in p16 genome were associated with development of gastric cancer and no significant correlation was demonstrated between the LOH frequency and the cell differentiated types of tumor cells or clinical stages. There was a positive relationship between the expression of hMSH2 mRNA and the differentiated types of gastric cancer.
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Affiliation(s)
- Qin-Xian Zhang
- Molecular Cell Biology Research Center, Medical College of Zhengzhou University; 40 Daxue Lu, Zhengzhou 450052, Henan Province, China.
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Wang YC, Lu YP, Tseng RC, Lin RK, Chang JW, Chen JT, Shih CM, Chen CY. Inactivation of hMLH1 and hMSH2 by promoter methylation in primary non-small cell lung tumors and matched sputum samples. J Clin Invest 2003; 111:887-95. [PMID: 12639995 PMCID: PMC153761 DOI: 10.1172/jci15475] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We performed a genetic and epigenetic study of the hMLH1 and hMSH2 mismatch repair genes in resected primary tumors from 77 non-small cell lung cancer (NSCLC) patients. The molecular alterations examined included the loss of mRNA and protein expression as well as promoter methylation, and the allelic imbalance of the chromosomal regions that harbor the genes. We found that 78% and 26% of patients showed at least one type of molecular alteration within the hMLH1 and hMSH2 genes, respectively. Promoter methylation of the hMLH1 gene was present in 55.8% of tumors, and was significantly associated with the reduction in mRNA and protein expression (P = 0.001). A 72% concordance of aberrant methylation in sputum samples with matched resected tumors was found. In addition, a 93% consistency between the promoter methylation and the mRNA expression of the hMSH2 gene was found in 14 female NSCLC patients. However, no correlation was found between the expression of hMLH1 and hMSH2 proteins and the allelic imbalance of five microsatellite markers closely linked to the genes. Our results suggest that hMLH1 is the major altered mismatch repair gene involved in NSCLC tumorigenesis, and that promoter methylation is the predominant mechanism in hMLH1 and hMSH2 deregulation. In addition, promoter methylation of the hMLH1 gene may be identified in sputum samples to serve as a potential diagnostic marker of NSCLC.
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Affiliation(s)
- Yi-Ching Wang
- Department of Biology, National Taiwan Normal University, Taipei, Taiwan, Republic of China.
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35
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Miyakura Y, Sugano K, Konishi F, Fukayama N, Igarashi S, Kotake K, Matsui T, Koyama Y, Maekawa M, Nagai H. Methylation profile of the MLH1 promoter region and their relationship to colorectal carcinogenesis. Genes Chromosomes Cancer 2003; 36:17-25. [PMID: 12461746 DOI: 10.1002/gcc.10134] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Methylation of the MLH1 promoter region has been suggested to be a principal mechanism of gene inactivation in sporadic microsatellite instability (MSI)-positive colorectal carcinoma. Recently, we have shown a novel methylation profile of the MLH1 promoter region (i.e., full, partial, and no methylation), among which full methylation was strongly associated with MSI. In this study, to confirm whether methylation requires the involvement of both alleles, we studied the MLH1 promoter region concerning the methylation profile and allelic loss. Furthermore, we studied correlations of methylation profiles with genetic alternations such as loss of heterozygosity (LOH) of the TP53 locus and KRAS mutation. Eighty-eight tumors were classified as full (n = 14), partial (n = 26), and no methylation (n = 48). Full methylation was observed in 78% (14/18) of high-frequency MSI, in which all CpG sites in the promoter region were methylated. Full methylation differed significantly from partial methylation regarding absence of TP53 LOH (0/12) and KRAS mutation (0/14). In cases with full methylation, we could show biallelic methylation by use of a single-base nucleotide polymorphism in the promoter. However, this did not accompany LOH of the MLH1 locus. In contrast, there were no significant differences in molecular features between partial and no methylation, except for low frequencies of LOH of the MLH1 locus (P = 0.02). In conclusion, biallelic extensive methylation of the MLH1 promoter region plays a significant role in gene inactivation and is independent of KRAS mutation and TP53 LOH.
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Abstract
PURPOSE OF REVIEW The purpose of this review is to discuss early and recent reports investigating microsatellite instability and mismatch repair expression in prostate cancer. RECENT FINDINGS Human mismatch repair genes encode highly conserved interacting proteins that suppress genetic instability by correcting misincorporated nucleotides and insertion/deletion mispairs formed during DNA replication. Mismatch repair deficiency causes genetic instability at microsatellite sequences because of the cell's inability to correct errors caused by DNA polymerase slippage at repetitive sequences. Microsatellite instability is characteristic of mismatch repair deficiency, and has been used as a surrogate marker for the inactivation of mismatch repair genes. Inherited mismatch repair gene mutations predispose to gastrointestinal and genitourinary malignancies in a cancer predisposition syndrome known as hereditary non-polyposis colorectal carcinoma. Although strong evidence for an inherited predisposition to prostate cancer does not exist in hereditary non-polyposis colorectal carcinoma, mismatch repair deficiency and mismatch repair gene mutations have been described in sporadic prostate cancer and prostate cancer cell lines. Early reports detected microsatellite instability in prostate cancer, and correlated this genetic alteration to clinical and pathological findings in men diagnosed with this malignancy. Recent reports have identified mismatch repair gene mutations, mismatch repair deficiency and differential mismatch repair gene expression in prostate cancer. In addition, a prognostic role for mismatch repair gene expression in prostate cancer has been suggested. SUMMARY The early identification of microsatellite instability in prostate cancer led to more specific investigation of mismatch repair gene expression. Although additional research is required, mismatch repair gene expression may have important biological and clinical significance in prostate cancer.
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Affiliation(s)
- Fredrick S Leach
- Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 77030, USA.
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37
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Bjørheim J, Gaudernack G, Ekstrøm PO. Melting gel techniques in single nucleotide polymorphism and mutation detection: From theory to automation. J Sep Sci 2002. [DOI: 10.1002/1615-9314(20020701)25:10/11<637::aid-jssc637>3.0.co;2-l] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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38
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Abstract
BACKGROUND It is widely accepted that the adenoma-carcinoma sequence represents the process by which most, if not all, colorectal cancers arise. The evidence supporting this hypothesis has increased rapidly in recent years and the purpose of this article is to review this evidence critically and highlight its clinical significance. METHODS Medline searches were used to identify recent key articles relating to the adenoma-carcinoma sequence. Further pertinent articles were obtained by manual scanning of the reference lists of identified papers. RESULTS The evidence supporting the adenoma-carcinoma sequence can be classified as epidemiological, clinicopathological and genetic. The most recent and largest body of data relates to molecular genetic events and their cellular effects; however, many other approaches, such as cytogenetics, molecular cytogenetics and cytometry, have also yielded valuable information. CONCLUSION Recent work continues to support the adenoma-carcinoma sequence, but there is a paucity of data on the interrelationship between different genetic mutations and on the relationship between molecular and other types of genetic abnormalities. The clinical utility of the observations described has yet to be fully realized and global genetic analysis of colorectal tumours may prove to be central in rational adenoma management.
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Affiliation(s)
- A Leslie
- Department of Surgery and Molecular Oncology, University of Dundee, Ninewells Hospital, Dundee, UK.
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39
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Rossi BM, Lopes A, Oliveira Ferreira F, Nakagawa WT, Napoli Ferreira CC, Casali Da Rocha JC, Simpson CC, Simpson AJG. hMLH1 and hMSH2 gene mutation in Brazilian families with suspected hereditary nonpolyposis colorectal cancer. Ann Surg Oncol 2002; 9:555-61. [PMID: 12095971 DOI: 10.1007/bf02573891] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND The aim of this study was to search for mutations in the human mutS homolog 2 (hMSH2) and human mutL homolog 1 (hMLH1) genes in 25 unrelated Brazilian kindreds with suspected hereditary nonpolyposis colorectal cancer (HNPCC). METHODS The families were grouped according to the following clinical criteria: Amsterdam I or II; familial colorectal cancer (CRC); an early age of onset of CRC in the proband only; or with at least one or two relatives who had HNPCC-related cancers; CRC in the proband only. All patients were studied with direct sequencing. RESULTS Ten mutations were detected (10 of 25 [40%]); of nine different mutations, seven were novel. The hMLH1 gene had a higher mutation detection rate than hMSH2 (8 of 25 [32%] vs. 2 of 25 [8%]). Only 3 of these 10 families fulfilled the Amsterdam criteria. Two different polymorphisms were detected in the hMLH1 gene and four in the hMSH2 gene. CONCLUSIONS The hMLH1 gene had a higher mutation detection rate than hMSH2. The physician who deals with CRC must take into consideration the heredity issue with patients who present with an early age of onset or a familial history of CRC- or HNPCC-related cancers, including gastric cancer, even if they do not fulfill the former Amsterdam criteria.
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Affiliation(s)
- Benedito Mauro Rossi
- Department of Pelvic Surgery, the Hospital do Câncer A. C. Camargo, Fundação Antonio Prudente, São Paulo, Brazil
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Hatta Y, Koeffler HP. Role of tumor suppressor genes in the development of adult T cell leukemia/lymphoma (ATLL). Leukemia 2002; 16:1069-85. [PMID: 12040438 DOI: 10.1038/sj.leu.2402458] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2001] [Accepted: 12/31/2001] [Indexed: 01/11/2023]
Abstract
Adult T cell leukemia/lymphoma (ATLL) is one of the peripheral T cell malignant neoplasms strongly associated with human T cell leukemia virus type-I (HTLV-I). Although the viral transactivating protein Tax has been proposed to play a critical role in leukemogeneis as shown by its transforming activity in various experimental systems, additional cellular events are required for the development of ATLL. One of the genetic events in ATLL is inactivation of tumor suppressor genes. Among many candidates for tumor suppressor genes, the main genetic events have been reported to center around the cyclin-dependent kinase inhibitors ((CDKIs) p15INK4A, p16INK4B, p18INK4C, p19INK4D, p21WAF1, p27KIP1, and p57KIP2), p53 and Rb genes; all of them play a major regulatory role during G1 to S transition in the cell cycle. Acute/lymphomatous ATLL has frequent alterations of p15 (20%) and p16 (28-67%), while chronic/smoldering ATLL has fewer abnormalities of p15 (0-13%) and p16 (5-26%). Most of these changes are deletion of the genes; fewer samples have mutations. ATLL patients with deleted p15 and/or p16 genes have significantly shorter survival than those individuals with both genes preserved. Although genetic alterations of p18, p19, p21, p27 have rarely been reported, inactivation of these genes may contribute to the development of ATLL because low expression levels of these genes seem to mark ATLL. The p53 gene is mutated in 10-50% of acute/lymphomatous ATLL. Functional impairment of the p53 protein, even if the gene has wild-type sequences, has been suggested in HTLV-I infected cells. Each of these genetic events are mainly found in acute/lymphomatous ATLL, suggesting that alterations of these genes may be associated with transformation to an aggressive phenotype. The Rb tumor suppressor gene is infrequently structurally altered, but one half of ATLL cases have lost expression of this key protein. Notably, alterations of one of the CDKIs, p53 and Rb genes appear to obviate the need for inactivation of other genes in the same pathway. A novel tumor suppressor gene on chromosome 6q may also have a critical role in the pathogenesis of ATLL. Taken together, tumor suppressor genes are frequently altered in acute/lymphomatous ATLL and their alteration is probably the driving force fueling the transition from chronic/smoldering to acute/lymphomatous ATLL.
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Affiliation(s)
- Y Hatta
- First Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan
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Heinen CD, Wilson T, Mazurek A, Berardini M, Butz C, Fishel R. HNPCC mutations in hMSH2 result in reduced hMSH2-hMSH6 molecular switch functions. Cancer Cell 2002; 1:469-78. [PMID: 12124176 DOI: 10.1016/s1535-6108(02)00073-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Mutations in the human mismatch repair (MMR) gene hMSH2 have been linked to approximately 40% of hereditary nonpolyposis colorectal cancers (HNPCC). While the consequences of deletion or truncating mutations of hMSH2 would appear clear, the detailed functional defects associated with missense alterations are unknown. We have examined the effect of seven single amino acid substitutions associated with HNPCC that cover the structural subdomains of the hMSH2 protein. We show that alterations which produced a known cancer-causing phenotype affected the mismatch-dependent molecular switch function of the biologically relevant hMSH2-hMSH6 heterodimer. Our observations demonstrate that amino acid substitutions within hMSH2 that are distant from known functional regions significantly alter biochemical activity and the ability of hMSH2-hMSH6 to form a sliding clamp.
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Affiliation(s)
- Christopher D Heinen
- Genetics and Molecular Biology Program, Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Kruschewski M, Noske A, Haier J, Runkel N, Anagnostopoulos Y, Buhr HJ. Is reduced expression of mismatch repair genes MLH1 and MSH2 in patients with sporadic colorectal cancer related to their prognosis? Clin Exp Metastasis 2002; 19:71-7. [PMID: 11918085 DOI: 10.1023/a:1013853224644] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The majority of mutations in hereditary nonpolyposis colon carcinoma (HNPCC) patients affect the mismatch-repair genes (MMRG) MLHI and MSH2. In addition, mutations of these genes were found in about 15% of sporadic colorectal carcinomas which appear to be related to microsatellite instability (MSI). However, mutations in MMRG were not found in all MSI-positive carcinomas, but MMRG mutations may be relevant for the assessment of tumor characteristics and patients' prognosis. Therefore, we investigated the relationship between expression of MMRG, tumor biology and patients' survival. In 127 patients with sporadic colorectal carcinomas and a minimum of 5 years follow-up after curative surgery immunohistochemical detection of MLHI and MSH2 was analyzed semiquantitatively. Lost expression of MLHI has been found in tumor specimens from 10 patients, whereas MSH2 expression was missing in 5 patients. This reduced expression did not correlate with tumor stage, lymph node involvement, grading or tumor invasion into blood vessels. However, a significant correlation was found for lymphovascular invasion (P = 0.02) and localization within the colorectum (P = 0.003) in MLH1-negative carcinomas. In addition, although there was a clear tendency for longer overall survival (72 vs. 63 months) for patients with MLH1-negative carcinomas, significant differences for overall and recurrence-free survival were not seen. In conclusion of our results and a critical review of literature, the prognostic importance of the MMR genes in sporadic colorectal carcinomas remains controversial.
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Affiliation(s)
- Martin Kruschewski
- Department of Surgery, University Hospital Benjamin Franklin, Free University of Berlin, Germany.
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Velasco A, Hewitt SM, Albert PS, Hossein M, Rosenberg H, Martinez C, Sagalowsky AI, McConnell JD, Marston W, Leach FS. Differential expression of the mismatch repair gene hMSH2 in malignant prostate tissue is associated with cancer recurrence. Cancer 2002; 94:690-9. [PMID: 11857301 DOI: 10.1002/cncr.10247] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Mismatch repair (MMR) genes are responsible for coordinated correction of misincorporated nucleotides formed during DNA replication. Inactivating mutations in MMR genes have been described in sporadic cancers and a hereditary cancer predisposition syndrome. Mismatch repair deficiency causes instability at microsatellites and increased mutation rates. Although microsatellite instability (MSI) has been described in high-grade and lymph node positive prostate carcinoma specimens, an analysis comparing hMSH2 expression, MSI, and outcome in clinically organ confined prostate carcinoma has not been reported. METHODS Immunohistochemical analysis of benign and malignant prostate tissue from 101 patients was performed using a monoclonal antibody specific for the hMSH2 protein. Expression was correlated with MSI using dinucleotide repeat markers and laser-captured microdissected DNA from normal and tumor cells. hMSH2 protein expression and MSI were assessed with respect to pathologic stage, Gleason score, and time to detectable serum prostate specific antigen (PSA) after prostatectomy in patients with clinically localized prostate carcinoma. RESULTS In normal glands, hMSH2 staining was minimal to low and confined to the basal cell layer. In 32% of benign prostatic hyperplasia cases, hMSH2 staining was increased in the basal and luminal cell layers whereas 71% of cancer specimens had uniform moderate to high staining. Microsatellite instability was detected in 60% of absent to low staining and 26% of moderate to high staining prostate carcinoma specimens. Differential staining in benign versus malignant prostate tissues was statistically significant (P < 0.001) as was the correlation between absent to low hMSH2 staining and presence of MSI (P = 0.028). Decreased risk for PSA recurrence after radical prostatectomy correlated with absent to low hMSH2 staining in malignant prostate tissue but was only marginally significant (P = 0.05 for 24 month recurrence and P = 0.08 for overall time to PSA recurrence). CONCLUSIONS The results of the current study demonstrate differential hMSH2 expression in benign and malignant prostate tissue. Moreover, hMSH2 expression is altered in a subset of clinically localized prostate carcinoma specimens independent of pathologic stage and Gleason pattern. A statistically significant correlation between hMSH2 immunohistochemical staining intensity and MSI also was identified in prostate carcinoma specimens. Furthermore, the time to cancer recurrence as determined by detectable serum PSA after prostatectomy was associated with hMSH2 staining intensity. Taken together, our results suggest that hMSH2 gene expression in prostate carcinoma may be a useful prognostic marker for outcome in men with clinically organ confined prostate carcinoma.
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Affiliation(s)
- Alfredo Velasco
- Urologic Oncology Branch, National Cancer Institute, Bethesda, Maryland 20892-1501, USA
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Pibouin L, Villaudy J, Ferbus D, Muleris M, Prospéri MT, Remvikos Y, Goubin G. Cloning of the mRNA of overexpression in colon carcinoma-1: a sequence overexpressed in a subset of colon carcinomas. CANCER GENETICS AND CYTOGENETICS 2002; 133:55-60. [PMID: 11890990 DOI: 10.1016/s0165-4608(01)00634-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have identified a novel human cDNA overexpressed in a colon carcinoma cell line, TC7, established from a tumor with a normal karyotype arising in a patient with a hereditary nonpolyposis colorectal carcinoma. The OCC-1 (overexpressed in colon carcinoma-1) gene is composed of six exons and located in the q24.1 region of chromosome 12. It is transcribed as two mRNA species that differ in their 5'- and 3'-terminal ends. Abundant accumulation of both transcripts was found in placenta, skeletal muscle, kidney, and pancreas tissues. Absent or very faint expression was observed in heart, brain, lung and liver tissues. Overexpressed in colon carcinoma-1 cDNA direct in vitro translation of several polypeptides whose size is shorter than 9 kDa. Attempts to produce antibodies against these synthesized polypeptides in Escherichia coli failed. The absence of sequences at the mRNA and DNA levels hybridizing with mouse sequences together with the absence of a large open reading frame raise the possibility that OCC-1 sequences appeared recently in evolution and are transcribed as two noncoding regulatory RNA. Elevated levels of OCC-1 mRNA were observed in three of eight colon carcinomas as compared to normal mucosa of the same patient. Since these tumors shared the same characteristics of having a near diploid karyotype, OCC-1 overexpression may be a hallmark of this subset of colon carcinomas.
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Affiliation(s)
- Laurence Pibouin
- Laboratoire d'Oncogenèse, UMR147 CNRS, Institut Curie, 26, rue d'Ulm, 75248, Cedex 05, Paris, France
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Fearnhead NS, Wilding JL, Bodmer WF. Genetics of colorectal cancer: hereditary aspects and overview of colorectal tumorigenesis. Br Med Bull 2002; 64:27-43. [PMID: 12421723 DOI: 10.1093/bmb/64.1.27] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Familial adenomatous polyposis and hereditary non-polyposis colorectal cancer are dominantly inherited conditions with 100% and 80% life-time risk of developing colorectal cancer, respectively. The genetic mutations responsible for these two conditions lie in the adenomatous polyposis coli (APC) and mismatch repair genes. These same genes also play a key role in the formation of sporadic colorectal cancers, which arise on a background of a similar spectrum of mutations to the hereditary cancers. This article examines the genetic mechanisms underlying the hereditary colorectal cancers, as well as genetic predisposition to colorectal cancer in the general population in the absence of a clear-cut genetic syndrome. Colorectal cancer arises as the cumulative effect of multiple mutations within the cell, allowing it to escape growth and regulatory control mechanisms. This step-wise progression of mutations facilitates the histological transition from normal mucosa to adenoma to carcinoma. The latter part of this paper focuses on the key genetic events underlying this process and provides an overview of the genetic mechanisms responsible for colorectal tumorigenesis.
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Affiliation(s)
- Nicola S Fearnhead
- Cancer Research UK, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DZ, UK
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Kuwada SK, Neklason DW, Burt RW. Biology and Molecular Genetics of Colorectal Cancer. COLORECTAL CANCER 2002. [DOI: 10.1007/978-1-59259-160-2_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Amin NS, Nguyen MN, Oh S, Kolodner RD. exo1-Dependent mutator mutations: model system for studying functional interactions in mismatch repair. Mol Cell Biol 2001; 21:5142-55. [PMID: 11438669 PMCID: PMC87239 DOI: 10.1128/mcb.21.15.5142-5155.2001] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2001] [Accepted: 04/20/2001] [Indexed: 12/24/2022] Open
Abstract
EXO1 interacts with MSH2 and MLH1 and has been proposed to be a redundant exonuclease that functions in mismatch repair (MMR). To better understand the role of EXO1 in mismatch repair, a genetic screen was performed to identify mutations that increase the mutation rates caused by weak mutator mutations such as exo1Delta and pms1-A130V mutations. In a screen starting with an exo1 mutation, exo1-dependent mutator mutations were obtained in MLH1, PMS1, MSH2, MSH3, POL30 (PCNA), POL32, and RNR1, whereas starting with the weak pms1 allele pms1-A130V, pms1-dependent mutator mutations were identified in MLH1, MSH2, MSH3, MSH6, and EXO1. These mutations only cause weak MMR defects as single mutants but cause strong MMR defects when combined with each other. Most of the mutations obtained caused amino acid substitutions in MLH1 or PMS1, and these clustered in either the ATP-binding region or the MLH1-PMS1 interaction regions of these proteins. The mutations showed two other types of interactions: specific pairs of mutations showed unlinked noncomplementation in diploid strains, and the defect caused by pairs of mutations could be suppressed by high-copy-number expression of a third gene, an effect that showed allele and overexpressed gene specificity. These results support a model in which EXO1 plays a structural role in MMR and stabilizes multiprotein complexes containing a number of MMR proteins. A similar role is proposed for PCNA based on the data presented.
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Affiliation(s)
- N S Amin
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, California 92093-0660, USA
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Thykjaer T, Christensen M, Clark AB, Hansen LR, Kunkel TA, Ørntoft TF. Functional analysis of the mismatch repair system in bladder cancer. Br J Cancer 2001; 85:568-75. [PMID: 11506498 PMCID: PMC2364098 DOI: 10.1054/bjoc.2001.1949] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
In bladder cancer the observed microsatellite instability indicates that mismatch repair deficiency could be a frequently involved factor in bladder cancer progression. To investigate this hypothesis we analysed extracts of seven bladder cancer cell lines and, as a novel approach, five clinical cancer samples for mismatch repair activity. We found that one cell line (T24) and three of the clinical samples had a reduced repair capacity, measured to approximately 20% or less. The T24 cell extract was unable to repair a G-G mismatch and showed reduced repair of a 2-base loop, consistent with diminished function of the MSH2-MSH6 heterodimer. The functional assay was combined with measurement for mutation frequency, microsatellite analysis, sequencing, MTT assay, immunohistochemical analysis and RT-PCR analysis of the mismatch repair genes MSH2, MSH3, MSH6, PMS1, PMS2 and MLH1. A >7-fold relative increase in mutation frequency was observed for T24 compared to a bladder cancer cell line with a fully functional mismatch repair system. Neither microsatellite instability, loss of repair nor mismatch repair gene mutations were detected. However, RT-PCR analysis of mRNA levels did detect changes in the ratio of expression of the Mut S and Mut L homologues. The T24 cell line had the lowest MSH6 expression level of the cell lines tested. Identical RT-PCR analysis of seventeen clinical samples (normal urothelium, 7; pTa low stage, 5; and pT1-4 high stage, 5) indicated a significant change in the expression ratio between MSH3/MSH6 (P< 0.004), MSH2/MSH3 (P< 0.012) and PMS2/MLH1 P< 0.005, in high stage bladder tumours compared to normal urothelium and low stage tumours. Collectively, the data suggest that imbalanced expression of mismatch repair genes could lead to partial loss of mismatch repair activity that is associated with invasive bladder cancer.
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Affiliation(s)
- T Thykjaer
- Department of Clinical Biochemistry, Skejby University Hospital, 8200 Aarhus N, Denmark
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Potocnik U, Glavac D, Golouh R, Ravnik-Glavac M. Causes of microsatellite instability in colorectal tumors: implications for hereditary non-polyposis colorectal cancer screening. ACTA ACUST UNITED AC 2001; 126:85-96. [PMID: 11376800 DOI: 10.1016/s0165-4608(00)00399-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Microsatellite instability (MSI) analysis was performed using a "reference panel" of microsatellite markers in 345 unselected primary colorectal cancers (CRC). Thirty-five (10%) tumors were classified as high MSI (MSI-H). We identified 6 (17%) MSI-H tumors with germline mutations in mismatch repair (MMR) genes (tumors from patients with hereditary non-polyposis colorectal cancer (HNPCC) syndrome) and 29 (83%) MSI-H tumors without germline MMR mutations (sporadic MSI-H tumors). Hypermethylation of the hMLH1 promoter was found in 26/29 (90%) sporadic MSI-H tumors but only in 1/6 (17%) HNPCC tumors (P<.001). Somatic alterations were identified in both MMR genes in HNPCC tumors but mainly in the hMSH2 gene in sporadic MSI-H tumors. LOH at MMR loci was detected in 3/6 (50%) HNPCC tumors and in 4/26 (15%) informative sporadic MSI-H tumors. These results together indicate different mode of inactivation of MMR genes in sporadic MSI-H tumors versus MSI-H tumors in HNPCC patients. We therefore propose that MSI analysis of newly diagnosed primary CRC followed by methylation analysis of hMLH1 promoter in MSI-H tumors and mutational analysis of MMR genes in MSI-H tumors lacking hMLH1 promoter methylation might be an efficient molecular genetic approach for HNPCC screening.
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Affiliation(s)
- U Potocnik
- Laboratory of Molecular Genetics, Institute of Pathology, Medical Faculty, Ljubljana, Slovenia
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