Downregulation of EphA7 by hypermethylation in colorectal cancer.
A significant reduction of EphA7 expression in human colorectal cancers was shown using semiquantitative reverse transcription-polymerase chain reaction analysis in 59 colorectal cancer tissues, compared to corresponding normal mucosas (P=0.008), and five colon cancer cell lines. To investigate the mechanism of EphA7 downregulation in colorectal cancer, we examined the methylation status of the 5'CpG island around the translation start site in five colon cancer cell lines using restriction enzymes, methylation-specific PCR, and bisulfite sequencing and found evidence of aberrant methylation. The expression of EphA7 in colon cancer cell lines was restored after treatment with 5-aza-2'-deoxycytidine. Analysis of methylation status in totally 75 tumors compared to clinicopathological parameters revealed that hypermethylation of colorectal cancers was more frequent in male than in female (P=0.0078), and in moderately differentiated than in well-differentiated adenocarcinomas (P=0.0361). There was a tendency that hypermethylation in rectal cancers was more frequent than in colon cancers (P=0.0816). Hypermethylation was also observed in colorectal adenomas. This is the first report describing the downregulation of an Eph family gene in a solid tumor via aberrant 5'CpG island methylation. It provides the evidence that EphA7 gene is involved in human colorectal carcinogenesis.
Wang
Jiandong
J
Department of Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu 431-3192, Japan.
Kataoka
Hideki
H
Suzuki
Masaya
M
Sato
Naomi
N
Nakamura
Ritsuko
R
Tao
Hong
H
Maruyama
Keiji
K
Isogaki
Jun
J
Kanaoka
Shigeru
S
Ihara
Megumi
M
Tanaka
Masamitsu
M
Kanamori
Masao
M
Nakamura
Toshio
T
Shinmura
Kazuya
K
Sugimura
Haruhiko
H
D000368:Aged; D002460:Cell Line; D015179:Colorectal Neoplasms / Q000145:classification / Q000235:genetics* / Q000473:pathology; D018899:CpG Islands; D019175:DNA Methylation; D015536:Down-Regulation / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D036141:Receptor, EphA7 / Q000235:genetics*; D012727:Sex Characteristics
D012333:RNA, Messenger; D036141:Receptor, EphA7