CpG island methylation status in gastric carcinoma with and without infection of Epstein-Barr virus.
OBJECTIVE
EBV-associated gastric carcinoma shows global CpG island methylation of the promoter region of various cancer-related genes. To further clarify the significance of CpG island methylator phenotype (CIMP) status in gastric carcinoma, we investigated methylation profile and clinicopathologic features including overall survival in four subgroups defined by EBV infection and CIMP status: EBV-associated gastric carcinoma and EBV-negative/CIMP-high (H), EBV-intermediate (I), and EBV-negative (N) gastric carcinoma.


METHODS
Methylation-specific PCR was applied to 106 gastric carcinoma cases. CIMP-N, CIMP-I, and CIMP-H status was determined by the number (0, 1-3, and 4-5, respectively) of methylated marker genes (LOX, HRASLS, FLNc, HAND1, and TM), that were newly identified as highly methylated in gastric cancer cell lines. The methylation status of 10 other cancer-related genes (p14, p15, p16, p73, TIMP-3, E-cadherin, DAPK, GSTP1, hMLH1, and MGMT) was also evaluated.


RESULTS
Nearly all (14 of 15) of EBV-associated gastric carcinoma exhibited CIMP-H, constituting a homogenous group (14%). EBV-negative gastric carcinoma consisted of CIMP-H (24%), CIMP-I (38%), and CIMP-N (24%). EBV-associated gastric carcinoma showed significantly higher frequencies of methylation of cancer-related genes (mean number +/- SD = 6.9 +/- 1.5) even if compared with EBV-negative/CIMP-H gastric carcinoma (3.5 +/- 1.8). Among EBV-negative gastric carcinoma subgroups, CIMP-H gastric carcinoma showed comparatively higher frequency of methylation than CIMP-I or CIMP-N, especially of p16 and hMLH1. CIMP-N gastric carcinoma predominantly consisted of advanced carcinoma with significantly higher frequency of lymph node metastasis. The prognosis of the patients of CIMP-N was significantly worse compared with other groups overall by univariate analysis (P = 0.0313).


CONCLUSIONS
The methylation profile of five representative genes is useful to stratify gastric carcinomas into biologically different subgroups. EBV-associated gastric carcinoma showed global CpG island methylation, comprising a pathogenetically distinct subgroup in CIMP-H gastric carcinoma.
Chang
Moon-Sung
MS
Department of Pathology, Graduate School of Medicine and Genome Science Division, Research Center for Advanced Science and Technology, University of Tokyo, Bunkyo, Tokyo, Japan.
Uozaki
Hiroshi
H
Chong
Ja-Mun
JM
Ushiku
Tetsuo
T
Sakuma
Kazuya
K
Ishikawa
Shunpei
S
Hino
Rumi
R
Barua
Rita Rani
RR
Iwasaki
Yoshiaki
Y
Arai
Kuniyoshi
K
Fujii
Hideki
H
Nagai
Hideo
H
Fukayama
Masashi
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology / Q000821:virology*; D016022:Case-Control Studies; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D020031:Epstein-Barr Virus Infections; D005260:Female; D052138:Genes, Neoplasm; D005819:Genetic Markers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011401:Promoter Regions, Genetic; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology / Q000821:virology*; D016019:Survival Analysis; D014407:Tumor Cells, Cultured
D005819:Genetic Markers