title: MSH2 and MLH1 mutations in sporadic replication error-positive colorectal carcinoma as assessed by two-dimensional DNA electrophoresis.
abstract: Replication errors (RER) are frequently seen in both sporadic and hereditary forms of colorectal cancer. In hereditary nonpolyposis colorectal cancer (HNPCC), RER is associated with defects in DNA mismatch repair genes. Two of these genes, MSH2 and MLH1, account for a major share of this cancer syndrome. In order to assess the role of these genes in sporadic RER+ colorectal carcinoma, we have carried out a mutation analysis of MSH2 and MLH1 by two-dimensional (2-D) DNA electrophoresis, including heteroduplexing and separation in a denaturing gradient. All exons were amplified using multiplex PCR and were separated on the basis of both size and base pair composition under a single set of experimental conditions. Exons showing a spot position different from normal were sequenced. In screening 33 unselected, sporadic RER+ colorectal tumors, a germline mutation accompanied by loss of heterozygosity in tumor tissue was found in two patients. They were among the 4 patients out of the 33 screened that were diagnosed before the age of 50 years. In 8 of the remaining 31 tumors (26%), presence of somatic mutations (9 in total) could be demonstrated. While suggesting involvement of other genes in a substantial part of sporadic RER+ colorectal carcinomas, our results also demonstrate a clear role of MSH2 and MLH1 in these sporadic tumors and show that young sporadic RER+ colorectal carcinoma patients have a high probability of germline mutations. This has important implications for genetic testing and management of young colorectal cancer patients and their families.
authors.affiliation: Department of Medical Genetics, University of Groningen, The Netherlands.
authors.forename: Y
authors.initials: Y
authors.lastname: Wu
authors.forename: M
authors.initials: M
authors.lastname: Nyström-Lahti
authors.forename: J
authors.initials: J
authors.lastname: Osinga
authors.forename: M W
authors.initials: MW
authors.lastname: Looman
authors.forename: P
authors.initials: P
authors.lastname: Peltomäki
authors.forename: L A
authors.initials: LA
authors.lastname: Aaltonen
authors.forename: A
authors.initials: A
authors.lastname: de la Chapelle
authors.forename: R M
authors.initials: RM
authors.lastname: Hofstra
authors.forename: C H
authors.initials: CH
authors.lastname: Buys
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000368:Aged; D002352:Carrier Proteins; D002869:Chromosome Aberrations; D003001:Cloning, Molecular; D015179:Colorectal Neoplasms / Q000235:genetics*; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000032:analysis; D004268:DNA-Binding Proteins; D015180:Electrophoresis, Gel, Two-Dimensional; D018095:Germ-Line Mutation; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics*; D009687:Nuclear Proteins; D011110:Polymorphism, Genetic; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein