Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA repair is of fundamental importance for protection of the genetic material against mutations in an interplay with mechanisms that regulate the cell cycle, gene expression, and programmed cell death. Defects in DNA repair, or in processes in tegrated with DNA repair, may give cells a hyper mutable phenotype that increases the likelihood of mutations in genes controlling cell growth. Two principally different DNA repair mechanisms are known; (a) direct repair of a damaged base by a single enzyme without using information from the complementary strand, and (b) excision repair, in which DNA containing the damage is removed and replaced by new DNA using DNA repair synthesis. Mechanisms for excision repair are complex and comprise base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), and recombination repair. In addition, the cell has mechanisms for repair of strand breaks. It has recently become clear that defective MMR is the cause of hereditary nonpolyposis colon cancer (HNPCC), and probably some 15% of the cases of sporadic colon cancer. There is also evidence that defective repair may be a primary cause of certain other forms of cancer.
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PMID:[DNA repair enzymes and their genes]. 965 90

MSH5 (MutS homologue 5) is a member of a family of proteins known to be involved in DNA mismatch repair. Germline mutations in MSH2, MLH1 and GTBP (also known as MSH6) cause hereditary non-polyposis colon cancer (HNPCC) or Lynch syndrome. Inactivation of Msh2, Mlh1, Gtmbp (also known as Msh6) or Pms2 in mice leads to hereditary predisposition to intestinal and other cancers. Early studies in yeast revealed a role for some of these proteins, including Msh5, in meiosis. Gene targeting studies in mice confirmed roles for Mlh1 and Pms2 in mammalian meiosis. To assess the role of Msh5 in mammals, we generated and characterized mice with a null mutation in Msh5. Msh5-/- mice are viable but sterile. Meiosis in these mice is affected due to the disruption of chromosome pairing in prophase I. We found that this meiotic failure leads to a diminution in testicular size and a complete loss of ovarian structures. Our results show that normal Msh5 function is essential for meiotic progression and, in females, gonadal maintenance.
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PMID:Mammalian MutS homologue 5 is required for chromosome pairing in meiosis. 991 5

The true incidence of rectal cancer in HNPCC is still unknown. In our retrospective series analyzing 42 probands from HNPCC families, we found rectal cancer primaries in 29% of our probands. Patients with a first cancer diagnosed in the rectum developed metachronous colon cancer in 54% of the cases. These numbers indicate a requirement to discuss the most appropriate surgical procedure for preventive intervention (ileorectal anastomosis versus ileoanal pouch procedure).
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PMID:[Rectal carcinomas in HNPCC]. 993 14

The large bowel is a leading site for cancers in developed countries whereas small bowel cancers are rare worldwide. The incidence rates of both large and small bowel cancer are low in India, and rectal cancer is more common than colon cancer. The incidence rates of colon cancer in eight population registries vary from 3.7 to 0.7/100,000 among men and 3 to 0.4/100,000 among women. For rectal cancer the incidence rates range from 5.5 to 1.6/100,000 among men and 2.8 to 0/100,000 among women. One intriguing observation is the occurrence of rectal cancer in young Indians. Rural incidence rates for large bowel cancers in India are approximately half of urban rates. Based on data from eight registries, we estimate that, in the year 2001, the incidence of large bowel cancer in India will be 18,427 in men and 13,092 in women. Immigrant studies reveal an increase in incidence as compared to the rates in native counterparts. Reliable time trends for India are available only from the Bombay registry. Significant increase in the incidence of colon cancer has been reported for both men and women over two decades, but the rates of rectal cancer are steady. The low incidence of large bowel cancers in Indians can be attributed to high intake of starch and the presence of natural antioxidants such as curcumin in Indian cooking. The role of hereditary factors has been evaluated in a few studies. Some studies have reported the occurrence of both FAP and HNPCC in India. There are no Indian studies on large bowel cancer prevention. The prevalence of adenomas is rare in elderly Indians undergoing colonoscopy, even in those with large bowel cancers. Small bowel cancers are extremely rare in India and no analytical studies have been published. Hospital-based data suggest that lymphomas of small bowel are more common than carcinomas. In conclusion, the incidence of large and small bowel adenomas and cancers is low in Indians. Increase in the incidence of large bowel cancers in immigrants and urban Indians compared to rural populations supports a role for environmental risk factors including diet. High rates of rectal cancers in young Indians could suggest a different etiopathogenesis, which is neither inherited nor traditional diet-related.
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PMID:Epidemiology of digestive tract cancers in India. V. Large and small bowel. 1040 66

The authors report a case of non-polyposis colon cancer in a seventeen year old female without prior polyposis or family history. Since it was the first case in this family, HNPCC was suspected. The polymerase chain reaction (PCR) of the tumor revealed changes in four polymorphic regions. Analysis of two of them, indicated the loss of genetic material confirming instability suggestive of HNPCC. The patient underwent ileorectal anastomosis and adjuvant chemotherapy with a good outcome. The authors discuss the importance of family history, genetic and immunohistochemistry studies, and the instability of microsatellites in adolescents with colorectal cancer.
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PMID:Genetics and colorectal cancer (HNPCC) in adolescence. A case report. 1043 36

A patient who had triple cancer (colon cancer, endometrial cancer, and ovarian cancer) in HNPCC kindred is reported. Her family history revealed the occurrence of colon cancer in her paternal aunt and in two cousins, fulfilling the minimum HNPCC criteria. Microsatellite instability analysis revealed replication error (RER)+ in all cancer lesions at 2 microsatellite loci (D1S191, BAT 40). SSCP analysis suggested germline mutation in exon 2 of the hMSH2 gene. This case showed the importance of complete family-history investigations to identify HNPCC patients. In the near future, definitive diagnosis of HNPCC will be possible on the basis of DNA studies.
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PMID:Microsatellite instability and hMSH2 gene mutation in a triple cancer (colon cancer, endometrial cancer, ovarian cancer) patient in hereditary non-polyposis colorectal cancer (HNPCC) kindred. 1068 Mar 34

Lynch syndrome is a peculiar disease, accounting for 5% of the total burden of colon cancer. Characteristics of this disease are autosomal dominant transmission, early onset, and frequent right colon localization. Diagnostic criteria, aimed to collaborative studies, are based on these features (so called Amsterdam criteria). Lynch syndrome has specific biomolecular features (microsatellite instability); mismatch repair genes have been identified as responsible of this syndrome. Lynch syndrome causes high risk for extracolonic malignancies, particularly for endometrial cancer, supposed to be related to mutation of hMSH2 gene. Another feature of Lynch syndrome tumours is better survival with respect to sporadic counterpart. Genetic test allows identifying the state of mutation carriers and selects the patients to submit to screening. Endoscopic screening has been demonstrated to reduce incidence of colorectal malignancies in this syndrome.
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PMID:[The Lynch syndrome]. 1068 68

Familial risk of colon cancer is a commonly encountered issue, involving both rare inherited syndromes of colon cancer and common familial clustering of cases. The genes that give rise to the rare syndromes of FAP and HNPCC are now known and current research is addressing the cellular mechanisms of these genes and the proper application of genetic testing in families with one of the syndromes. Common familial clustering of cases appears to arise from an interaction of mildly to moderately severe inherited susceptibility factors with certain environmental factors to give rise to adenomatous polyps and then finally colorectal cancer. Research in this area involves identification of these purportedly more common susceptibility genes, and determination of how each interacts with environmental factors to give rise to polyps and cancer. Optimal application of varying degrees of familial risk to screening strategies is also being determined.
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PMID:Familial association. 1070 79

Deficiencies in DNA mismatch repair (MMR) have been found in hereditary colon cancers (hereditary non-polyposis colon cancer, HNPCC) as well as in sporadic cancers, illustrating the importance of MMR in maintaining genomic integrity. We have examined the interactions of specific mismatch repair proteins in human nuclear extracts. Western blot and co-immunoprecipitation studies indicate two complexes as follows: one consisting of hMSH2, hMSH6, hMLH1, and hPMS2 and the other consisting of hMSH2, hMSH6, hMLH1, and hPMS1. These interactions occur without the addition of ATP. Furthermore, the protein complexes specifically bind to mismatched DNA and not to a similar homoduplex oligonucleotide. The protein complex-DNA interactions occur primarily through hMSH6, although hMSH2 can also become cross-linked to the mismatched substrate when not participating in the MMR protein complex. In the presence of ATP the binding of hMSH6 to mismatched DNA is decreased. In addition, hMLH1, hPMS2, and hPMS1 no longer interact with each other or with the hMutSalpha complex (hMSH2 and hMSH6). However, the ability of hMLH1 to co-immunoprecipitate mismatched DNA increases in the presence of ATP. This interaction is dependent on the presence of the mismatch and does not appear to involve a direct binding of hMLH1 to the DNA.
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PMID:Identification of mismatch repair protein complexes in HeLa nuclear extracts and their interaction with heteroduplex DNA. 1074 59

The APC I1307K gene mutation is associated with increased colorectal cancer (CRC) risk in Ashkenazi Jews. Factors predicting acceptance of this and other hereditary colon cancer mutation tests in a clinical setting are unknown. We analyzed sex, age, family history, personal history, and gene test results of patients at increased risk for cancer who sought cancer risk counseling at the Johns Hopkins (JH) CRC Risk Assessment Clinic (n = 91), and those submitting samples to the JH Pathology Molecular Diagnostic Laboratory (n = 256) for APC I1307K testing. Of patients seen at the JH Clinic, 77/91 (84.6%) elected APC I1307K testing after pretest counseling (acceptors). There were no statistically significant differences in demographic characteristics between acceptors and decliners. In comparison, only 8 of 57 (14.0%) patients offered HNPCC testing proceeded with testing (P < 0.001). Of 256 individuals tested at the JH laboratory, most were male (61.3%) and most had a personal or family history of colorectal cancer or polyps. Test positivity correlated with increasing risk of colorectal cancer. Acceptance of testing for the APC I1307K mutation is high, with more men than women pursuing counseling and testing. The reported association between the APC I1307K mutation and colon cancer risk was supported by a correlation in these data between personal or family history of CRC or polyps and a gene mutation.
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PMID:Response to genetic counseling and testing for the APC I1307K mutation. 1075 45


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