Methylation of CpG sites in exon 2 of the bcl-2 gene occurs in colorectal carcinoma

Anticancer Res. Jul-Aug 2001;21(4A):2809-14.


Background: Aberrant bcl-2 expression frequently occurs in colorectal carcinoma. The current study investigated if CpG sites in bcl-2 were methylated in colorectal carcinoma and if methylation correlated with loss of expression of bcl-2 mRNA.

Methods: Methylation was assessed in 23 matched normal mucosae and colonic carcinomas by Southern blotting with methylation-sensitive enzymes. Expression of bcl-2 mRNA was assessed by Northern blotting.

Results: A SacII site in exon 2 of the bcl-2 gene was methylated in 5 carcinomas, plus an adjacent HpaII sites in 1 tumour. SacII site in the bcl-2 promoter were not methylated. Elevated levels of bcl-2 mRNA were detected in 3 carcinomas, 5 showed decreased expression and 4 were unchanged.

Conclusions: De novo methylation of CpG sites in exon 2 of the bcl-2 gene occurs during the development of colorectal carcinoma. However, there was no relationship between expression of bc1-2 mRNA and methylation of specific CpG sites.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Northern
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / metabolism
  • Colorectal Neoplasms / pathology
  • CpG Islands*
  • DNA Methylation*
  • DNA-Cytosine Methylases / metabolism
  • Deoxyribonucleases, Type II Site-Specific / metabolism
  • Exons
  • Gene Expression Regulation, Neoplastic
  • Genes, bcl-2 / genetics*
  • Humans
  • Neoplasm Staging
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins c-bcl-2 / biosynthesis
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics


  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • DNA modification methylase HpaII
  • DNA-Cytosine Methylases
  • CCGCGG-specific type II deoxyribonucleases
  • Deoxyribonucleases, Type II Site-Specific