RRC ID 78657
Author Zou B, Chim CS, Zeng H, Leung SY, Yang Y, Tu SP, Lin MC, Wang J, He H, Jiang SH, Sun YW, Yu LF, Yuen ST, Kung HF, Wong BC.
Title Correlation between the single-site CpG methylation and expression silencing of the XAF1 gene in human gastric and colon cancers.
Journal Gastroenterology
Abstract BACKGROUND & AIMS:X-linked inhibitor of apoptosis protein (XIAP)-associated factor 1 (XAF1) antagonizes the anti-caspase activity of XIAP. XAF1 messenger RNA is present in normal tissues but undetectable in various cancers and thus poses a potential tumor suppressor gene. The aim of this study was to examine the novel pattern of methylation of XAF1 in gastric and colon cancers and locate the important CpG sites for transcriptional regulation and tumor progression.
METHODS:XAF1 expression was detected by reverse-transcription polymerase chain reaction (PCR) and Western blot analysis. Four different fragments around the transcription start site of XAF1 were cloned and examined putative promoter activities by luciferase reporter assay. Each CpG site in fragment F291 was mutated by site-directed mutagenesis technique, and the change of promoter activity of this fragment was detected by luciferase reporter assay. Methylation status of XAF1 was determined by methylation-specific PCR (MSP) and bisulfite DNA sequencing PCR analysis.
RESULTS:Down-regulation of XAF1 in association with hypermethylation was detected in 3 of 4 human gastric cancer cell lines and 6 of 8 colon cancer cell lines. Of the 4 promoter fragments, F291 showed the highest promoter activity, which could be down-regulated obviously by the mutation of particular CpG sites. Moreover, aberrant hypermethylation of these important CpG sites was strongly associated with the development of gastric and colon cancers.
CONCLUSIONS:A cluster of methylated CpG sites instead of CpG islands located in the promoter area resulted in gene silencing of XAF1, and CpGs at -2nd, -1st, and +3rd positions are functionally more important in its transcriptional regulation.
Volume 131(6)
Pages 1835-43
Published 2006-12-1
DOI 10.1053/j.gastro.2006.09.050
PII S0016-5085(06)02218-9
PMID 17087954
MeSH Adaptor Proteins, Signal Transducing Adult Aged Aged, 80 and over Antimetabolites, Antineoplastic / pharmacology Apoptosis Regulatory Proteins Azacitidine / analogs & derivatives Azacitidine / pharmacology Cell Line, Tumor Colonic Neoplasms / genetics* Colonic Neoplasms / metabolism CpG Islands DNA Methylation* DNA, Neoplasm / genetics* Decitabine Down-Regulation / drug effects Female Gene Expression Regulation, Neoplastic* / drug effects Gene Silencing* Humans Hydroxamic Acids / pharmacology Intracellular Signaling Peptides and Proteins Male Middle Aged Neoplasm Proteins / genetics* Neoplasm Proteins / metabolism Promoter Regions, Genetic / genetics Protein Synthesis Inhibitors / pharmacology RNA, Messenger / genetics RNA, Messenger / metabolism Stomach Neoplasms / genetics* Stomach Neoplasms / metabolism
IF 17.373
Resource
Human and Animal Cells MKN45(RCB1001)