title: Morphologically normal-appearing mammary epithelial cells obtained from high-risk women exhibit methylation silencing of INK4a/ARF.
abstract: OBJECTIVE
  p16(INK4a) has been appreciated as a key regulator of cell cycle progression and senescence. Cultured human mammary epithelial cells that lack p16(INK4a) activity have been shown to exhibit premalignant phenotypes, such as telomeric dysfunction, centrosomal dysfunction, a sustained stress response, and, most recently, a dysregulation of chromatin remodeling and DNA methylation. These data suggest that cells that lack p16(INK4a) activity would be at high risk for breast cancer development and may exhibit an increased frequency of DNA methylation events in early cancer.
  
  
  METHODS
  To test this hypothesis, the frequencies of INK4a/ARF promoter hypermethylation, as well as four additional selected loci, were tested in the initial random periareolar fine needle aspiration samples from 86 asymptomatic women at high risk for development of breast cancer, stratified using the Masood cytology index.
  
  
  RESULTS
  INK4a/ARF promoter hypermethylation was observed throughout all early stages of intraepithelial neoplasia and, importantly, in morphologically normal-appearing mammary epithelial cells; 29 of 86 subjects showed INK4a/ARF promoter hypermethylation in at least one breast. Importantly, INK4a/ARF promoter hypermethylation was not associated with atypia, and the frequency of hypermethylation did not increase with increasing Masood cytology score. The frequency of INK4a/ARF promoter hypermethylation was associated with the combined frequency of promoter hypermethylation of retinoic acid receptor-beta2, estrogen receptor-alpha, and breast cancer-associated 1 genes (P = 0.001).
  
  
  CONCLUSIONS
  Because INK4a/ARF promoter hypermethylation does not increase with age but increases with the frequency of other methylation events, we predict that INK4a/ARF promoter hypermethylation may serve as a marker of global methylation dysregulation.
authors.affiliation: Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Bean
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Bryson
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Pilie
authors.forename: Vanessa
authors.initials: V
authors.lastname: Goldenberg
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Baker
authors.forename: Catherine
authors.initials: C
authors.lastname: Ibarra
authors.forename: Danielle M U
authors.initials: DM
authors.lastname: Brander
authors.forename: Carolyn
authors.initials: C
authors.lastname: Paisie
authors.forename: Natalie R
authors.initials: NR
authors.lastname: Case
authors.forename: Mona
authors.initials: M
authors.lastname: Gauthier
authors.forename: Paul A
authors.initials: PA
authors.lastname: Reynolds
authors.forename: Eric
authors.initials: E
authors.lastname: Dietze
authors.forename: Julie
authors.initials: J
authors.lastname: Ostrander
authors.forename: Victoria
authors.initials: V
authors.lastname: Scott
authors.forename: Lee G
authors.initials: LG
authors.lastname: Wilke
authors.forename: Lisa
authors.initials: L
authors.lastname: Yee
authors.forename: Bruce F
authors.initials: BF
authors.lastname: Kimler
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Fabian
authors.forename: Carola M
authors.initials: CM
authors.lastname: Zalles
authors.forename: Gloria
authors.initials: G
authors.lastname: Broadwater
authors.forename: Thea D
authors.initials: TD
authors.lastname: Tlsty
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Seewaldt
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D019175:DNA Methylation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology / Q000378:metabolism*; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D012306:Risk
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16