title: Promoter methylation primarily occurs in tumor cells of patients with non-small cell lung cancer.
abstract: BACKGROUND
  The distribution of promoter methylation throughout the lungs of patients with non-small cell lung cancer (NSCLC) is unknown. In this explorative study, we assessed the methylation status of the promoter region of 11 genes in brush samples of 3 well-defined endobronchial locations in patients with NSCLC and in brushes of former and current smokers without NSCLC.
  
  
  METHODS
  The methylation status of RASSF1A, GATA4, GATA5, SFRP1, RARbeta2, DAPK, MGMT, p16, p14, CHFR and APC2 was determined in all samples using real-time methylation-specific PCR.
  
  
  RESULTS
  Ten patients with NSCLC and 18 non-NSCLC controls were included. Eight patients had one or more methylated genes in their tumor brush. Promoter methylation of genes in proximal or contralateral locations was much less frequent than in tumor brushes, and almost exclusively occurred in normal tissue if the same gene was also methylated in the tumor brush.
  
  
  CONCLUSIONS
  Promoter methylation almost exclusively occurred in tumor cells of patients with NSCLC.
authors.affiliation: Department of Pulmonary Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. w.k.de.jong@int.umcg.nl
authors.forename: Wouter K
authors.initials: WK
authors.lastname: De Jong
authors.forename: Gonda F
authors.initials: GF
authors.lastname: Verpooten
authors.forename: Henk
authors.initials: H
authors.lastname: Kramer
authors.forename: Joost
authors.initials: J
authors.lastname: Louwagie
authors.forename: Harry J M
authors.initials: HJ
authors.lastname: Groen