title: Increased promoter methylation in exfoliated breast epithelial cells in women with a previous breast biopsy.
abstract: Accurately identifying women at increased risk of developing breast cancer will provide greater opportunity for early detection and prevention. DNA promoter methylation is a promising biomarker for assessing breast cancer risk. Breast milk contains large numbers of exfoliated epithelial cells that are ideal for methylation analyses. Exfoliated epithelial cells were isolated from the milk obtained from each breast of 134 women with a history of a non-proliferative benign breast biopsy (Biopsy Group). Promoter methylation of three tumor suppressor genes, RASSF1, SFRP1 and GSTP1, was assessed by pyrosequencing of bisulfite-modified DNA. Methylation scores from the milk of the 134 women in the Biopsy Group were compared to scores from 102 women for whom a breast biopsy was not a recruitment requirement (Reference Group). Mean methylation scores for RASSF1 and GSTP1 were significantly higher in the Biopsy than in the Reference Group. For all three genes the percentage of outlier scores was greater in the Biopsy than in the Reference Group but reached statistical significance only for GSTP1. A comparison between the biopsied and non-biopsied breasts of the Biopsy Group revealed higher mean methylation and a greater number of outlier scores in the biopsied breast for both SFRP1 and RASSF1, but not for GSTP1. This is the first evidence of CpG island methylation in tumor suppressor genes of women who may be at increased risk of developing breast cancer based on having had a prior breast biopsy.
authors.affiliation: Department of Veterinary and Animal Science, University of Massachusetts at Amherst, Amherst, MA, USA.
authors.forename: Eva P
authors.initials: EP
authors.lastname: Browne
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Punska
authors.forename: Sarah
authors.initials: S
authors.lastname: Lenington
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Otis
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Anderton
authors.forename: Kathleen F
authors.initials: KF
authors.lastname: Arcaro
mesh_terms: D000293:Adolescent; D000328:Adult; D001940:Breast / Q000378:metabolism* / Q000473:pathology; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D016147:Genes, Tumor Suppressor; D051549:Glutathione S-Transferase pi / Q000235:genetics; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D008895:Milk, Human / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic; D025521:Tumor Suppressor Proteins / Q000235:genetics; D000094742:Secreted Frizzled-Related Proteins
chemical_list: D051549:Glutathione S-Transferase pi; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D025521:Tumor Suppressor Proteins; C411762:RASSF1 protein, human; C117636:SFRP1 protein, human; D000094742:Secreted Frizzled-Related Proteins; C496556:GSTP1 protein, human