High frequency of microsatellite instability in intestinal-type gastric cancer in Korean patients.
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.
Choe
Won Hyuk
WH
Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Lee
Sun-Young
SY
Lee
Jun Haeng
JH
Shim
Sang Goon
SG
Kim
Young-Ho
YH
Rhee
Poong-Lyul
PL
Rhee
Jong Chul
JC
Ki
Chang-Seok
CS
Kim
Jong-Won
JW
Song
Sang Yong
SY
Kim
Jae J
JJ
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
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