DNA demethylase is expressed in ovarian cancers and the expression correlates with demethylation of CpG sites in the promoter region of c-erbB-2 and survivin genes

Cancer Lett. 2001 Aug 28;169(2):155-64. doi: 10.1016/s0304-3835(01)00499-2.


The objectives of this study were to examine DNA demethylase (dMTase) expression in ovarian cancers and evaluate methylation of CpG sites in the promoter of the c-erbB-2 gene and survivin gene exon 1. Forty-three epithelial ovarian cancers and 43 non-cancerous ovarian tissues were studied for dMTase expression by RT-PCR. Genomic DNA was extracted and digested with HindIII and then HpaII. CpG site-sensitive primers were constructed to amplify the promoter of the c-erbB-2 gene and survivin gene exon 1. Immunohistochemical evaluation of ErbB-2 protein and RT-PCR for survivin were also performed. dMTase was positive in 88.4% of ovarian cancers but only in 9.3% of non-cancerous ovaries (P<0.001, Fisher's exact test). The expression was similarly observed in both early stage (stage I+II: 17/19) and advanced stage (stage III+IV: 21/24) groups of ovarian malignancy. It was found that 78.9% of dMTase-positive cancers had both c-erbB-2 promoter and survivin gene exon 1 unmethylated, whereas 40% of dMTase-negative cancers had both sites methylated. In non-cancerous ovaries, these sites were mostly methylated (90.6%) and the difference from cancer cases was highly significant (P<0.001). Immunohistochemical evaluation of ErbB-2 showed significant correlation of unmethylated c-erbB-2 promoter and ErbB-2 expression. The RT-PCR for survivin expression showed that 86% of cancers were positive and six cases were negative. Exon 1 was methylated in 83% of the survivin-negative cases. This is the first report of dMTase expression in ovarian cancers. The correlation of dMTase expression with unmethylation of c-erbB-2 promoter and survivin gene exon 1 suggests that these sites may be targets for demethylation by the enzyme. The up-regulation of oncogenes may be the consequence of epigenetic control of gene expression by the dMTase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • CpG Islands*
  • DNA / metabolism
  • DNA Methylation*
  • DNA, Complementary / metabolism
  • Exons
  • Female
  • Humans
  • Immunohistochemistry
  • Inhibitor of Apoptosis Proteins
  • Microtubule-Associated Proteins*
  • Middle Aged
  • Neoplasm Proteins
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / metabolism*
  • Ovary / pathology
  • Oxidoreductases, O-Demethylating / biosynthesis*
  • Polymerase Chain Reaction
  • Promoter Regions, Genetic*
  • Proteins / genetics*
  • Receptor, ErbB-2 / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Survivin
  • Temperature


  • BIRC5 protein, human
  • DNA, Complementary
  • Inhibitor of Apoptosis Proteins
  • Microtubule-Associated Proteins
  • Neoplasm Proteins
  • Proteins
  • Survivin
  • DNA
  • Oxidoreductases, O-Demethylating
  • methyl-CpG DNA demethylase
  • Receptor, ErbB-2