Site-specific DNA methylation contributes to neurotensin/neuromedin N expression in colon cancers

Zizheng Dong, Xiaofu Wang, B. Mark Evers

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

The neurotensin/neuromedin N (NT/N) gene is expressed in fetal colon, repressed in newborn and adult colon, and reexpressed in ~25% of colon cancers. Our purpose was to determine the effect of gene methylation on NT/N silencing in colon cancers. We found that the NT/N gene was expressed in human colon cancer cell line KM12C but not in KM20 colon cancer cells. Bisulfite genomic sequencing demonstrated that all CpG dinucleotides in the region from -373 to +100 of the NT/N promoter, including a CpG site in a distal consensus AP-1 site, were methylated in KM20 but unmethylated in KM12C cells. Treatment of KM20 cells with demethylating agent 5-azacytidine induced NT/N expression, suggesting a role for DNA methylation in silencing of NT/N in colon cancers. To better elucidate the mechanisms responsible for NT/N repression by DNA methylation, we performed gel shift assays using an oligonucleotide probe corresponding to the distal AP-1 consensus sequence of the NT/N promoter. Methylation of the oligonucleotide probe inhibited protein binding to the distal AP-1 site of the NT/N promoter, suggesting a potential mechanism of NT/N gene repression in colon cancers. We show that DNA methylation plays a role in NT/N gene silencing in the human colon cancer KM20 and that NT/N expression in KM12C cells is associated with demethylation of the CpG sites. DNA methylation likely contributes to NT/N gene expression noted in human colon cancers.

Original languageEnglish (US)
Pages (from-to)G1139-G1147
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume279
Issue number6 42-6
DOIs
StatePublished - Jan 1 2000

Keywords

  • Colon cancer cells
  • Gene expression

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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