title: Microsatellite instability in esophageal squamous cell carcinoma is not associated with hMLH1 promoter hypermethylation.
abstract: To test whether a subset of esophageal squamous cell carcinomas (SCC) develop through a deficiency in DNA mismatch repair, we examined microsatellite instability (MSI) using 11 microsatellite markers including BAT-26, hMLH1 protein expression by immunohistochemistry, and methylation status of the hMLH1 promoter by methylation-specific polymerase chain reaction (MSP). p53 mutations were also investigated. Microsatellite instability at one or more loci was observed in 40% (12/30) of esophageal SCC tumor samples, although only one of these tumors was categorized as high-frequency MSI (MSI-H) and none showed BAT-26 instability. While immunohistochemistry revealed decreased hMLH1 protein expression in 27% (8/30) of the tumors, hMLH1 promoter hypermethylation was not observed. Absence of hMLH1 protein expression was relatively common in well-differentiated (keratinizing-type) esophageal SCC, but was not associated with hMLH1 promoter hypermethylation. p53 mutation was detected in 37% (11/30) and loss of heterozygosity (LOH) in 90% (27/30) of esophageal SCC samples. Our results suggested that most esophageal SCC develop through defects in tumor suppressor genes (i.e. the suppressor pathway), and that MSI in esophageal SCC probably represent random replication errors rather than being associated with DNA mismatch repair deficiency.
authors.affiliation: Department of Pathology, Yamagata University School of Medicine, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hayashi
authors.forename: Gen
authors.initials: G
authors.lastname: Tamura
authors.forename: Zhe
authors.initials: Z
authors.lastname: Jin
authors.forename: Izumi
authors.initials: I
authors.lastname: Kato
authors.forename: Makoto
authors.initials: M
authors.lastname: Sato
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Shibuya
authors.forename: Suran
authors.initials: S
authors.lastname: Yang
authors.forename: Teiichi
authors.initials: T
authors.lastname: Motoyama
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D016158:Genes, p53; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011401:Promoter Regions, Genetic
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004273:DNA, Neoplasm; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000070957:MutL Protein Homolog 1