E-Cadherin gene promoter hypermethylation in primary human gastric carcinomas.
BACKGROUND
E (epithelial)-cadherin, the cell adhesion molecule also considered a potential invasion/metastasis suppressor, is mutationally inactivated in nearly half of all undifferentiated-scattered (diffuse-type) gastric carcinomas. In addition, silencing of E-cadherin by CpG methylation within its promoter region has been reported in several gastric carcinoma cell lines. We investigated the methylation status of the E-cadherin promoter region in 53 primary human gastric carcinomas.


METHODS
Hypermethylation of the E-cadherin promoter was determined by utilizing methylation-specific polymerase chain reaction (PCR)-single-strand conformation polymorphism (MSP-SSCP) analysis followed by direct sequencing of PCR products. Expression of E-cadherin was studied by western blot analysis. All statistical tests were two-sided.


RESULTS
Hypermethylation of the E-cadherin promoter was evident in 27 (51%) of 53 primary gastric carcinomas examined by MSP-SSCP. It occurred more frequently in carcinomas of the undifferentiated-scattered type (in 15 [83%] of 18) than in other histologic subtypes (in 12 [34%] of 35) (P =.0011, Fisher's exact test), and it was present at similar rates in early (in six [60%] of 10) versus advanced (in 21 [49%] of 43) carcinomas (P =.73, Fisher's exact test). Methylation occurring at all cytosine-guanosine sequences (CpGs) near the transcriptional start site was confirmed in six of six tumors examined by bisulfite-DNA sequencing, including two early gastric carcinomas. In addition, loss or diminished expression of E-cadherin was confirmed by western blotting in four of the six tumor tissues demonstrating hypermethylation.


CONCLUSIONS
The E-cadherin promoter frequently undergoes hypermethylation in human gastric cancers, particularly those of the undifferentiated-scattered histologic subtype. E-cadherin promoter hypermethylation is associated with decreased expression and may occur early in gastric carcinogenesis.
Tamura
G
G
Department of Medicine, Gastroenterology Division, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Yin
J
J
Wang
S
S
Fleisher
A S
AS
Zou
T
T
Abraham
J M
JM
Kong
D
D
Smolinski
K N
KN
Wilson
K T
KT
James
S P
SP
Silverberg
S G
SG
Nishizuka
S
S
Terashima
M
M
Motoyama
T
T
Meltzer
S J
SJ
D015153:Blotting, Western; D015820:Cadherins / Q000235:genetics*; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism*; D003596:Cytosine / Q000378:metabolism; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000737:chemistry; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006151:Guanosine / Q000378:metabolism; D006801:Humans; D008745:Methylation; D016133:Polymerase Chain Reaction / Q000379:methods; D018807:Polymorphism, Single-Stranded Conformational; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism*
D015820:Cadherins; D017931:DNA Primers; D004273:DNA, Neoplasm; D006151:Guanosine; D003596:Cytosine