Hypermethylation of the p14(ARF) gene in ulcerative colitis-associated colorectal carcinogenesis.
The p14(ARF) protein directly inhibits the MDM-2 oncoprotein, which mediates degradation of the p53 protein. It has been shown that p14(ARF) expression is frequently down-regulated by p14(ARF) gene hypermethylation in colorectal cancer. To determine whether p14(ARF) inactivation was involved in ulcerative colitis (UC)-associated carcinogenesis, the frequency and timing of p14(ARF) methylation was investigated in four different histological stages of UC-associated carcinogenesis. Methylation-specific PCR and bisulfite sequencing were used to determine the prevalence of p14(ARF) gene methylation. p14(ARF) methylation was observed in 19 of 38 (50%) adenocarcinomas, 4 of 12 (33%) dysplasias, and 3 of the 5 (60%) nonneoplastic UC mucosae. In contrast, 3 of 40 (3.7%) normal tissues showed p14(ARF) methylation (chi(2) test: P = 0.0003). Bisulfite sequencing was used to analyze 28 CpGs of p14(ARF) gene in 20 samples. The number of methylated CpGs ranged from 0 to 4, 0 to 20, and 0 to 28 in the normal, dysplastic, and carcinomatous samples, respectively (Kruskall-Wallis test: P = 0.0005). Densely methylated alleles were detected only in carcinomas by bisulfite sequencing. In conclusion, our data suggest that methylation of p14(ARF) is a relatively common early event in UC-associated carcinogenesis. p14(ARF) offers potential as a biomarker for the early detection of cancer or dysplasia in UC. Finally, analyses of p14(ARF) methylation in other organs should explore not only frank cancers but other premalignant lesions.
Sato
Fumiaki
F
Gastroenterology Division, Department of Medicine, University of Maryland School of Medicine and Gastroenterology Service, Baltimore, Maryland 21201, USA.
Harpaz
Noam
N
Shibata
David
D
Xu
Yan
Y
Yin
Jing
J
Mori
Yuriko
Y
Zou
Tong-Tong
TT
Wang
Suna
S
Desai
Kena
K
Leytin
Anatoly
A
Selaru
Florin M
FM
Abraham
John M
JM
Meltzer
Stephen J
SJ
D001483:Base Sequence; D003093:Colitis, Ulcerative / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000209:etiology / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA / Q000379:methods; D013447:Sulfites; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics*
D013447:Sulfites; D025803:Tumor Suppressor Protein p14ARF