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

Tomasz K Wojdacz,Lise Lotte Hansen,Britta B Thestrup,Jens Overgaard

doi:10.1186/1746-1596-6-116

Tomasz K Wojdacz, Lise Lotte Hansen + Show 2 more

Open Access

https://doi.org/10.1186/1746-1596-6-116

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Abstract

BackgroundRecently 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.FindingsWe 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.ConclusionsOur 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.

Highlights

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
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 may only be specific to PB DNA
Much attention is paid to the phenomenon of hypermethylation of disease related genes in peripheral blood (PB) DNA and its involvement in the pathology of cancer and other diseases [1,2,3,4,5,6]

Summary

Introduction

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 those studies the authors have examined methylation status of the BRCA1 promoter in PB and paired tumor DNA, only a subset of the tumors, developed by patients with PB BRCA1 methylation, harbored tumor specific methylation of BRCA1 [2,17]. The study by Wong et al [2] involved 12 breast cancer patients with paired tumor and PB DNA samples.

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