Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0009402 (colorectal cancer)
 53,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Instability of microsatellite repeat sequences has been observed in colorectal carcinomas and in extracolonic malignancies, predominantly endometrial tumours, occurring in the context of hereditary non-polyposis colorectal cancer (HNPCC). Microsatellite instability (MSI) as a feature of human DNA mismatch repair (MMR)-driven tumourigenesis of the uterine mucosa has been studied primarily in sporadic tumours showing predominantly somatic hypermethylation of MLH1. The present study shows that all endometrial carcinomas (n=12) from carriers of MLH1 and MSH2 germline mutations demonstrate an MSI-high phenotype involving all types of repeat markers, while in endometrial carcinomas from MSH6 mutation carriers, only 36% (4 out of 11) demonstrate an MSI-high phenotype. Interestingly, an MSI-high phenotype was found in endometrial hyperplasias from MSH2 mutation carriers, in contrast to hyperplasias from MLH1 mutation carriers, which exhibited an MSI-stable phenotype. Instability of only mononucleotide repeat markers was found in both endometrial carcinomas and hyperplasias from MSH6 mutation carriers. In 29 out of 31 (94%) endometrial tumour foci, combined MSI and immunohistochemical analysis of MLH1, MSH2, and MSH6 could predict the identified germline mutation. The observation of MSI in endometrial hyperplasia and of altered protein staining for the MMR genes supports the idea that inactivation of MMR genes is an early event in endometrial tumourigenesis. A correlation was found between the variation in the extent and level of MSI and the age of onset of carcinoma, suggesting differences in the rate of tumour progression. A high frequency of MSI in hyperplasias, found only in MSH2 mutation carriers, might indicate a more rapid tumour progression, correlating with an earlier age of onset of carcinoma. The present study indicates that assessment of altered protein staining combined with MSI analysis of endometrial tumours might direct the mutational analysis of MMR genes.
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PMID:Prediction of a mismatch repair gene defect by microsatellite instability and immunohistochemical analysis in endometrial tumours from HNPCC patients. 1105 16

Lynch syndrome is the most common hereditary form of colorectal cancer (CRC). Its natural history has been investigated extensively, so that highly targeted surveillance and management strategies, melded to its natural history, have proven effective in cancer control. Most important is the early age of onset of cancer (approximately 44 years), involving CRC and the several extracolonic cancers that are integral to the syndrome. With respect to CRC, approximately 70% of cases occur proximal to the splenic flexure. Synchronous and metachronous CRCs are extremely common. Full colonoscopy should be initiated when the patient is between the ages of 20 and 25, and because of the accelerated carcinogenesis of CRC, it should be performed every 1 to 2 years. The presence of initial CRC requires subtotal colectomy, given the mentioned increased frequency of metachronous cancer. Options available for germ-line mutation carriers, in addition to cancer screening, include prophylactic colectomy as well as prophylactic total abdominal hysterectomy and bilateral salpingo-oophorectomy. The discovery of mismatch repair germ-line mutations (most commonly MSH2 or MLH1) has added significantly to the recognition of this disease as well as to the search for high-risk individuals throughout families who, with genetic counseling, may become candidates for germ-line mutation testing. Clearly, hereditary nonpolyposis colorectal cancer provides an excellent opportunity for learning about the etio-pathogenesis of cancer at the molecular and clinical levels and how this knowledge might ultimately be exploited for cancer control. A search for chemoprevention agents, such as cyclo-oxygenase 2 inhibitors, as well as for putative environmental effects and how they may interact with the genetic component in CRC etiology should abet this entire cancer control process.
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PMID:Lynch syndrome: genetics, natural history, genetic counseling, and prevention. 1106 Mar 21

Sarcomas, including the malignant fibrous histiocytomas (MFHs), are not known to be part of the tumour spectrum of hereditary non-polyposis colorectal cancer (HNPCC) as epidemiologically established. Therefore, occurrence of MFH in an HNPCC family may very well be coincidental. HNPCC is associated with germline mutations in DNA mismatch repair genes, including the MSH2 gene. We analysed an MFH diagnosed in a 45-year-old male HNPCC patient carrying a germline MSH2 mutation for HNPCC-associated molecular characteristics, to investigate a possible relationship between the tumour and that mutation. DNA analysis revealed microsatellite instability and loss of one MSH2 copy, and immunohistochemistry showed absence of nuclear MSH2 protein staining. To investigate whether this is a common finding in MFH, microsatellite instability and nuclear MSH2 protein staining was tested for in 5 and 6 sporadic MFHs, respectively. None showed microsatellite instability and all stained positively for MSH2. Together, these findings show that in rare cases, MFH may be part of the HNPCC tumour spectrum.
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PMID:Inclusion of malignant fibrous histiocytoma in the tumour spectrum associated with hereditary non-polyposis colorectal cancer. 1106 81

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant inherited cancer susceptibility syndrome signifying a very high risk of colorectal and endometrial cancer at young age. It also entails an increased risk of a variety of other tumours, such as ovarian, gastric, uroepithelial and biliary tract cancer. The underlying pathogenic mutation lies in one of the five known DNA mismatch repair genes (MSH2, MLH1, PMS1, PMS2, and MSH2). The majority of HNPCC patients and families can at present be identified and the underlying mutation detected by genetic diagnostics. This provides the opportunity for predictive genetic testing to exclude or identify the mutation carrier status of the family members at risk. Mutation-negative individuals can then be relieved from any extra cancer threat. For mutation-positive individuals a preventive surveillance programme offers substantial benefits in reducing the cancer incidence, almost precluding death of colorectal cancer and reducing overall mortality.
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PMID:Surveillance on mutation carriers of DNA mismatch repair genes. 1107 89

Germ-line mutations in MLH1 and MSH2 genes predispose to hereditary non-polyposis colorectal cancer (HNPCC) syndrome, but they do not predict a specific phenotype of the disease. We speculated that the ataxia-telangiectasia mutated gene (ATM) was a candidate gene to modulate the phenotypic expression of HNPCC, as heterozygous individuals for germ-line ATM mutations have been considered at higher risk of developing epithelial malignancies. The frequency of the ATM D1853N polymorphism was evaluated in 167 individuals from 20 HNPCC families in which MLH1 or MSH2 germ-line mutations co-segregated with the disease. Among the 67 MLH1 or MSH2 mutation carriers, the ATM 1853N variant was associated with a significantly higher incidence of colorectal and other HNPCC-related cancers, when compared with individuals carrying the ATM 1853D variant [12/13 (92%) vs. 31/54 (57.5%); p = 0.02]. MLH1 and MSH2 mutation carriers who concomitantly carried the ATM 1853N variant, had an 8 times increased risk of developing colorectal and other HNPCC-related cancers (OR: 8.9; p = 0.02), when compared with MLH1 or MSH2 mutation carriers with the ATM 1853D variant. Our results suggest that the ATM D1853N polymorphism modulates the penetrance of MLH1 and MSH2 germ-line mutations.
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PMID:A polymorphism in the ATM gene modulates the penetrance of hereditary non-polyposis colorectal cancer. 1109 16

PMS2 is one of a complex of genes encoding DNA repair proteins that includes MSH2, MLH1, MSH6 and MSH3. Mutation of any of these DNA mismatch repair genes leads to impairment of DNA repair and can lead to tumorigenesis. Germline mutation of PMS2 has been reported as a rare cause of hereditary nonpolyposis colorectal cancer (HNPCC) and Turcot's syndrome. The PMS2 gene is located on chromosome 7p22 and consists of 15 exons. Within exon 11 of PMS2 is a coding repeat of eight adenosines. This study reports on the finding of a nonexpressed pseudogene that is highly homologous to the PMS2 gene in this region. The pseudogene is polymorphic for two alterations in the repeat region: a 3 bp delAAA at a site corresponding to nucleotide 1231 in PMS2; and an AA-->GG change at nucleotide 1238. Due to the high homology in both intronic and exonic sequences, polymorphisms in this pseudogene could be mistaken for mutations in the PMS2 gene and erroneously thought to be a cause of HNPCC and/or Turcot's syndrome.
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PMID:Polymorphisms in a pseudogene highly homologous to PMS2. 1110 87

The most sensitive technique for the detection of germline mutations is exon by exon sequencing of the gene under investigation using genomic DNA as a template for analysis. This approach, however, has cost and sensitivity limitations that can, at least in part, be overcome by RNA-based analysis. Germline mutations of MLH1 and MSH2 are the most frequent cause of the inherited susceptibility to colorectal and other epithelial cancers known as hereditary non-polyposis colorectal cancer (HNPCC). We compared the analysis of the MLH1 and MSH2 genes using mRNA and genomic DNA as starting material from 21 HNPCC patients. All samples were investigated by RT-PCR, sequencing of cDNA and simultaneous sequencing of genomic DNA. The cDNA was generated using specific primers complementary to the ends of MLH1 and MSH2 genes, respectively. Mutations in MLH1 and MSH2 were detected in 11 out of 21 unrelated patients. In 10 out of 11 cases, mutations were detected independently of the type of primers used for reverse transcription (RT). One novel missense mutation (K751R) in MLH1 was detected using this method. One nonsense mutation (E205X) in MSH2 was only detectable when RT was performed using MSH2 gene-specific primers. Shorter PCR products indicative of alternatively spliced transcripts were not observed when MLH1 or MSH2 specific cDNA RT primers were employed to generate template, except in one case where exon skipping was observed for exons 9 and 10. In this report we demonstrate that primers specific for RT of MLH1 and MSH2 are crucial for increasing the sensitivity of cDNA analysis. DNA sequencing using RNA as a basis for template construction may be a valuable and economical alternative to genomic DNA sequencing.
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PMID:Optimization of experimental conditions for RNA-based sequencing of MLH1 and MSH2 genes. 1113 42

A woman is described who developed an ovarian adenocarcinoma, 3 metachronous colorectal adenocarcinomas, and a primary adrenocortical adenocarcinoma. Genetic investigation of the mismatch repair genes MLH1 and MSH2 showed a germline mutation in MSH2. Colorectal and ovarian carcinoma belong to the tumor spectrum of hereditary nonpolyposis colorectal cancer (HNPCC). Adrenocortical adenocarcinoma, however, has never been described as 1 of the HNPCC-associated tumors. To investigate whether the adrenocortical adenocarcinoma in this patient was caused by the MSH2 germline mutation, determination of microsatellite instability (MSI) and immunohistochemical analysis were performed on 1 of the colorectal tumors and the adrenocortical adenocarcinoma. MSI and general loss of MSH2 protein expression could be seen in the colorectal tumor but not in the adrenocortical adenocarcinoma. Therefore, it is highly unlikely that the adrenocortical adenocarcinoma found in this patient was due to her genetic predisposition for HNPCC. HUM PATHOL 31:1522-1527.
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PMID:Adrenocortical adenocarcinoma in an MSH2 carrier: coincidence or causal relation? 1115 Mar 79

Mismatch repair (MMR) gene mutations cause hereditary nonpolyposis colorectal cancer (HNPCC), a common form of familial colorectal cancer. Among MMR genes, germline MSH6 mutations are often observed in HNPCC-like families with an increased frequency of endometrial cancer. We have previously shown that a proportion of women affected with double primary cancers of the colorectum and endometrium carry germline MSH2 or MLH1 mutations and, thus, belong to HNPCC families. In this study, we have investigated the specific contribution of MSH6 defects to such double primary patients. By sequence analysis of the entire coding region of MSH6, three putative missense mutations were identified in patients with atypical family histories that do not meet HNPCC criteria. Moreover, one of these mutations, a novel substitution Arg901 His, was found in a patient previously shown to carry a truncating germline MLH1 mutation. Thus, MSH6 mutations are likely to contribute to the etiology of double primary cancers of the colorectum and endometrium.
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PMID:Do MSH6 mutations contribute to double primary cancers of the colorectum and endometrium? 1115 17

Muir-Torre syndrome is an autosomal-dominant inherited disorder predisposing to both sebaceous skin tumors and internal neoplasms. In a significant proportion of Muir-Torre syndrome patients skin tumors exhibit microsatellite instability as a hallmark of hereditary nonpolyposis colorectal cancer. Most individuals predisposed to hereditary nonpolyposis colorectal cancer harbor a germline mutation in the DNA mismatch repair genes MSH2 or MLH1. In Muir-Torre syndrome the vast majority of germline mutations have been identified in MSH2. Microsatellite instability in tumor tissue develops after somatic inactivation of the corresponding second mismatch repair allele ("second hit"). So far, the mechanisms of somatic inactivation of the second allele in microsatellite instability positive tumors from patients with known mismatch repair germline mutations are not well understood. We examined whether allele loss (loss of heterozygosity) is a frequent mechanism for inactivation of the second MSH2 allele in a sample of nine microsatellite instability positive skin tumors from eight unrelated Muir-Torre patients with known MSH2 germline mutations. Loss of heterozygosity was determined using microsatellite markers or heteroduplex analysis, respectively. Only one of the nine skin tumors exhibited loss of heterozygosity at the MSH2 locus. Thus, we could show in a sample of sebaceous tumors from patients with genetically proven Muir-Torre syndrome that loss of heterozygosity most probably is not the preferred mode of somatic inactivation of the second MSH2 allele.
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PMID:"Second hit" in sebaceous tumors from Muir-Torre patients with germline mutations in MSH2: allele loss is not the preferred mode of inactivation. 1123 23


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