title: Promoter methylation in epithelial-enriched and epithelial-depleted cell populations isolated from breast milk.
abstract: BACKGROUND
  Breast cancer is the most frequently diagnosed cancer among Turkish women and both the incidence and associated mortality appear to be increasing. Of particular concern is the percentage of young women diagnosed with breast cancer; roughly 20% of all breast cancer diagnoses in Turkey are in women younger than 40 years. Increased DNA methylation in the promoter region of tumor suppressor genes is a promising molecular biomarker, and human milk provides exfoliated breast epithelial cells appropriate for DNA methylation analyses. Comparisons between DNA methylation patterns in epithelial (epithelial-enriched) and nonepithelial (epithelial-depleted) cell fractions from breast milk have not been reported previously.
  
  
  OBJECTIVE
  In the present study, we examined promoter methylation of 3 tumor suppressor genes in epithelial-enriched and epithelial-depleted cell fractions isolated from breast milk of 43 Turkish women.
  
  
  METHODS
  Percentage methylation in the promoter region of Rass association domain family 1 (RASSF1), secreted frizzle related protein 1 (SFRP1), and glutathione-S-transferase class pi 1 was determined by pyrosequencing of the epithelial-enriched and epithelial-depleted cell fractions.
  
  
  RESULTS
  Pyrosequencing identified a few subjects with significantly increased methylation in 1 or more genes. There was little correlation between the 2 cell fractions within individuals; only 1 woman had increased methylation for 1 gene (SFRP1) in both her enriched and depleted cell fractions. Methylation was positively associated with age for SFRP1 (epithelial-depleted fraction) and with body mass index for RASSF1 (epithelial-enriched cell fraction), respectively.
  
  
  CONCLUSIONS
  Overall, results show that the methylation signals vary between different cell types in breast milk and suggest that breast milk can be used to assess DNA methylation patterns associated with increased breast cancer risk.
authors.affiliation: Department of Veterinary & Animal Science, University of Massachusetts Amherst, Amherst, MA, USA.
authors.forename: Eva P
authors.initials: EP
authors.lastname: Browne
authors.affiliation: Department of Physiology, Faculty of Medicine, Yeditepe University, Istanbul, Turkey.
authors.forename: Signem E
authors.initials: SE
authors.lastname: Dinc
authors.affiliation: Department of Veterinary & Animal Science, University of Massachusetts Amherst, Amherst, MA, USA.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Punska
authors.affiliation: Department of Physiology, Faculty of Medicine, Yeditepe University, Istanbul, Turkey.
authors.forename: Sami
authors.initials: S
authors.lastname: Agus
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Yeditepe University, Istanbul, Turkey.
authors.forename: Ayca
authors.initials: A
authors.lastname: Vitrinel
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Yeditepe University, Istanbul, Turkey.
authors.forename: Gulay Ciler
authors.initials: GC
authors.lastname: Erdag
authors.affiliation: Department of Sociology, University of South Carolina, Columbia, SC, USA.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Anderton
authors.affiliation: Department of Veterinary & Animal Science, University of Massachusetts Amherst, Amherst, MA, USA.
authors.forename: Kathleen F
authors.initials: KF
authors.lastname: Arcaro
authors.affiliation: Department of Physiology, Faculty of Medicine, Yeditepe University, Istanbul, Turkey bayram2353@yahoo.com.
authors.forename: Bayram
authors.initials: B
authors.lastname: Yilmaz
mesh_terms: D000293:Adolescent; D000328:Adult; D001943:Breast Neoplasms / Q000235:genetics; D019175:DNA Methylation; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D020022:Genetic Predisposition to Disease; D051549:Glutathione S-Transferase pi / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D007774:Lactation; D008565:Membrane Proteins / Q000235:genetics; D008895:Milk, Human / Q000166:cytology*; D011795:Surveys and Questionnaires; D025521:Tumor Suppressor Proteins / Q000235:genetics*; D014421:Turkey; D044465:White People; D055815:Young Adult; 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
keywords: GSTP1; Istanbul; RASSF1; SFRP1; breast epithelial cells; breast milk; breastfeeding; promoter methylation; pyrosequencing