Methylation profiles of multiple CpG island loci in extrahepatic cholangiocarcinoma versus those of intrahepatic cholangiocarcinomas.
BACKGROUND
CpG island hypermethylation is attracting attention because of its importance as a tumor marker and its potential mechanism for the development of human cancers. Extrahepatic cholangiocarcinoma has been poorly investigated with respect to CpG island hypermethylation, and the number of genes known to be methylated in extrahepatic cholangiocarcinomas is fewer than 20.


OBJECTIVE
To generate methylation profiles of 24 CpG island loci in extrahepatic cholangiocarcinomas, to correlate methylation findings with clinicopathologic findings, and to compare these findings with those of intrahepatic cholangiocarcinomas.


METHODS
Sixty-three extrahepatic cholangiocarcinomas and 48 intrahepatic cholangiocarcinomas were investigated for hypermethylation in 24 CpG island loci by using methylation-specific polymerase chain reaction.


RESULTS
A total of 61 (96.8%) of 63 extrahepatic cholangiocarcinomas showed hypermethylation in at least one of the examined loci, and a high methylation frequency was seen in HOXA1 (95.2%), HPP1 (69.8%), and NEUROG1 (61.9%). The number of methylated CpG island loci was greater in extrahepatic cholangiocarcinomas with nodal metastasis than in those without nodal metastasis (P = .047), and hypermethylation of TIG1 was closely associated with nodal metastasis of extrahepatic cholangiocarcinomas (P = .007). CDH1 and NEUROG1 were more frequently methylated in extrahepatic cholangiocarcinoma than in intrahepatic cholangiocarcinoma, whereas CHFR, GSTP1, IGF2, MGMT, MINT31, p14, and RBP1 were more frequently methylated in intrahepatic cholangiocarcinoma: the differences was statistically significant (P < .05).


CONCLUSIONS
A close relationship exists between CpG island hypermethylation and nodal metastasis of extrahepatic cholangiocarcinomas. Methylation profiles of extrahepatic cholangiocarcinomas are somewhat similar to but distinct from those of intrahepatic cholangiocarcinomas.
Kim
Baek-Hee
BH
Department of Pathology, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744 South Korea.
Cho
Nam-Yun
NY
Choi
Minhee
M
Lee
Sun
S
Jang
Ja June
JJ
Kang
Gyeong Hoon
GH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001650:Bile Duct Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017734:Bile Ducts, Extrahepatic; D001653:Bile Ducts, Intrahepatic; D018281:Cholangiocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D004273:DNA, Neoplasm