Methylation of homeobox genes is a frequent and early epigenetic event in breast cancer

Breast Cancer Res. 2009;11(1):R14. doi: 10.1186/bcr2233. Epub 2009 Feb 27.


Introduction: Aberrant methylation of CpG islands is a hallmark of cancer and occurs at an early stage in breast tumorigenesis. However, its impact on tumor development is not fully determined, and its potential as a diagnostic biomarker remains to be validated. Methylation profiling of invasive breast carcinoma has been largely explored. Conversely, very little and sparse information is available on early-stage breast cancer. To gain insight into the epigenetic switches that may promote and/or contribute to the initial neoplastic events during breast carcinogenesis, we have analyzed the DNA methylation profile of ductal carcinoma in situ, a premalignant breast lesion with a great potential to progress toward invasive carcinoma.

Methods: We have utilized a comprehensive and sensitive array-based DNA mapping technique, the methylated-CpG island recovery assay, to profile the DNA methylation pattern in ductal carcinoma in situ. Differential methylation of CpG islands was compared genome-wide in tumor DNA versus normal DNA utilizing a statistical linear model in the LIMMA software package.

Results: Using this approach, we have identified 108 significant CpG islands that undergo aberrant DNA methylation in ductal carcinoma in situ and stage I breast tumors, with methylation frequencies greater than or comparable with those of more advanced invasive carcinoma (50% to 93%). A substantial fraction of these hypermethylated CpG islands (32% of the annotated CpG islands) is associated with several homeobox genes, such as the TLX1, HOXB13, and HNF1B genes. Fifty-three percent of the genes hypermethylated in early-stage breast cancer overlap with known Polycomb targets and include homeobox genes and other developmental transcription factors.

Conclusions: We have identified a series of new potential methylation biomarkers that may help elucidate the underlying mechanisms of breast tumorigenesis. More specifically, our results are suggestive of a critical role of homeobox gene methylation in the insurgence and/or progression of breast cancer.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology
  • Carcinoma, Ductal, Breast / genetics*
  • Carcinoma, Ductal, Breast / secondary
  • CpG Islands
  • DNA Methylation*
  • Epigenesis, Genetic*
  • Gene Expression Regulation, Neoplastic*
  • Genome, Human
  • Homeodomain Proteins / genetics*
  • Humans
  • Oligonucleotide Array Sequence Analysis
  • Prognosis
  • Promoter Regions, Genetic / genetics


  • Homeodomain Proteins