title: Methylation of cancer related genes in tumor and peripheral blood DNA from the same breast cancer patient as two independent events.
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.
  
  
  RESULTS
  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.
authors: The Lundbeck Foundation Centre for International Research in Radiation Oncology, Nørrebrogade 44, Building no, 5, Aarhus University Hospital, DK-8000 Aarhus C, Denmark. wojdacz@humgen.au.dk
authors: Tomasz K
authors: TK
authors: Wojdacz
authors: Britta B
authors: BB
authors: Thestrup
authors: Jens
authors: J
authors: Overgaard
authors: Lise Lotte
authors: LL
authors: Hansen
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics*; D019313:BRCA1 Protein / Q000235:genetics*; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000097:blood / Q000235:genetics* / Q000473:pathology; D004247:DNA / Q000097:blood / Q000235:genetics; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D006801:Humans; D011401:Promoter Regions, Genetic; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: C555337:APC protein, human; D025601:Adenomatous Polyposis Coli Protein; D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D004273:DNA, Neoplasm; C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins; D004247:DNA