title: High frequency of microsatellite instability in intestinal-type gastric cancer in Korean patients.
abstract: BACKGROUND
  Although there have been some reports on microsatellite alterations in gastric cancer, findings are inconsistent regarding the associations between histological classification and microsatellite instability (MSI). In the present study, we attempted to determine whether Lauren's histological subtypes are related with MSI status.
  
  
  METHODS
  Paraffin-embedded tissue samples from 14 diffuse-type and 14 intestinal-type gastric adenocarcinomas were matched up according to patient gender and age. Mononucleotide markers (BAT25 and BAT26) and dinucleotide markers (D2S123, D5S346, and D175S250) were used for MSI analyses. Microsatellite genotypes were categorized in terms of high MSI incidence (MSI-H, >30% positive marker) or low MSI incidence (MSI-L, <30% positive marker). Losses of hMLH1 and hMSH2 protein expression were immunohistochemically studied.
  
  
  RESULTS
  MSI-H was observed in 11 cases (78%) of the 14 intestinal-type cases as compared to 3 (21%) of the 14 diffuse-type cases (p=0.007). In MSI-H tumors, 10 cases (71%) showed losses of hMLH1 protein expression, while 2 cases (14%) in MSI-L tumors showed losses of hMLH1 protein expression (p=0.006).
  
  
  CONCLUSIONS
  MSI-H tumors are more frequently found in intestinal-type gastric cancer, which suggests the possibility that there are different pathogenic pathways in gastric carcinogenesis according to histologic type.
authors.affiliation: Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Won Hyuk
authors.initials: WH
authors.lastname: Choe
authors.forename: Sun-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Jun Haeng
authors.initials: JH
authors.lastname: Lee
authors.forename: Sang Goon
authors.initials: SG
authors.lastname: Shim
authors.forename: Young-Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Poong-Lyul
authors.initials: PL
authors.lastname: Rhee
authors.forename: Jong Chul
authors.initials: JC
authors.lastname: Rhee
authors.forename: Chang-Seok
authors.initials: CS
authors.lastname: Ki
authors.forename: Jong-Won
authors.initials: JW
authors.lastname: Kim
authors.forename: Sang Yong
authors.initials: SY
authors.lastname: Song
authors.forename: Jae J
authors.initials: JJ
authors.lastname: Kim
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000230:Adenocarcinoma / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D000368:Aged; D020137:Base Pair Mismatch / Q000235:genetics*; D002352:Carrier Proteins; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005838:Genotype; D006801:Humans; D015994:Incidence; D007723:Korea / Q000453:epidemiology; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics*; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins; D009363:Neoplasm Proteins / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; C088996:PMS1 protein, human; D012333:RNA, Messenger; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins