Aberrant promoter methylation and tumor suppressive activity of the DFNA5 gene in colorectal carcinoma

Oncogene. 2008 Jun 5;27(25):3624-34. doi: 10.1038/sj.onc.1211021. Epub 2008 Jan 28.


To identify novel methylated gene promoters, we compared differential RNA expression profiles of colorectal cancer (CRC) cell lines with or without treatment of 5-aza-2'-deoxycytidine (5-aza-dC). Out of 1776 genes that were initially 'absent (that is, silenced)' by gene expression array analysis, we selected 163 genes that were increased after 5-aza-dC treatment in at least two of three CRC cell lines. The microarray results were confirmed by Reverse Transcription-PCR, and CpG island of the gene promoters were amplified and sequenced for examination of cancer-specific methylation. Among the genes identified, the deafness, autosomal dominant 5 gene, DFNA5, promoter was found to be methylated in primary tumor tissues with high frequency (65%, 65/100). Quantitative methylation-specific PCR of DFNA5 clearly discriminated primary CRC tissues from normal colon tissues (3%, 3/100). The mRNA expression of DFNA5 in four of five colon cancer tissues was significantly downregulated as compared to normal tissues. Moreover, forced expression of full-length DFNA5 in CRC cell lines markedly decreased the cell growth and colony-forming ability whereas knockdown of DFNA5 increased cell growth in culture. Our data implicate DFNA5 as a novel tumor suppressor gene in CRC and a valuable molecular marker for human cancer.

MeSH terms

  • Carcinoma / genetics*
  • Cell Line, Tumor
  • Cell Proliferation
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology*
  • Colorectal Neoplasms / genetics*
  • DNA Methylation
  • Gene Expression Regulation, Neoplastic*
  • Gene Silencing
  • Genes, Tumor Suppressor
  • Humans
  • Models, Biological
  • Oligonucleotide Array Sequence Analysis
  • Promoter Regions, Genetic*
  • Receptors, Estrogen / genetics*
  • Receptors, Estrogen / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction


  • GSDME protein, human
  • Receptors, Estrogen