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Open Access Short report

Methylation of cancer related genes in tumor and peripheral blood DNA from the same breast cancer patient as two independent events

Tomasz K Wojdacz123*, Britta B Thestrup3, Jens Overgaard23 and Lise Lotte Hansen3

Author Affiliations

1 The Lundbeck Foundation Centre for International Research in Radiation Oncology, Nørrebrogade 44, Building no. 5, Aarhus University Hospital, DK-8000 Aarhus C, Denmark

2 Department of Experimental Clinical Oncology, Aarhus University Hospital, Nørrebrogade 44, Building no. 5, DK-8000 Aarhus C, Denmark

3 Department of Biomedicine, University of Aarhus, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark

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Diagnostic Pathology 2011, 6:116  doi:10.1186/1746-1596-6-116

Published: 30 November 2011

Abstract

Background

Recently it has been suggested that acquisition of methylation of the BRCA1 promoter detectable in peripheral blood (PB) DNA, could give raise to development of breast cancer. In this study, we aimed to investigate a relationship between methylation of three breast cancer related genes in PB DNA, and tumor specific (somatic) methylation of these genes in the same individual.

Findings

We have examined methylation status of the BRCA1, APC and RASSF1A promoter regions in a panel of 75 breast tumor and PB DNA samples from the same individual. In our study group, 4.0% of the patients displayed methylation of BRCA1 and APC in both tumor and the corresponding PB DNA. At the same time despite of marked methylation in tumor DNA, no methylation of BRCA1 and APC was seen in PB DNA of 4.3% and 2.7% of the patients respectively. The RASSF1A promoter did not show methylation in PB DNA.

Conclusions

Our results show that for at least a subset of cancer patients methylation of certain cancer related genes in PB DNA does not seem to be directly linked to somatic methylation of the same genes in tumor DNA, and therefore may only be specific to PB DNA.

Keywords:
Methylation; cancer predisposition; BRCA1; APC; RASSF1A.