title: Tumor-associated endothelial cells display GSTP1 and RARbeta2 promoter methylation in human prostate cancer.
abstract: BACKGROUND
  A functional blood supply is essential for tumor growth and proliferation. However, the mechanism of blood vessel recruitment to the tumor is still poorly understood. Ideally, a thorough molecular assessment of blood vessel cells would be critical in our comprehension of this process. Yet, to date, there is little known about the molecular makeup of the endothelial cells of tumor-associated blood vessels, due in part to the difficulty of isolating a pure population of endothelial cells from the heterogeneous tissue environment.
  
  
  METHODS
  Here we describe the use of a recently developed technique, Expression Microdissection, to isolate endothelial cells from the tumor microenvironment. The methylation status of the dissected samples was evaluated for GSTP1 and RARbeta2 promoters via the QMS-PCR method.
  
  
  RESULTS
  Comparing GSTP1 and RARbeta2 promoter methylation data, we show that 100% and 88% methylation is detected, respectively, in the tumor areas, both in epithelium and endothelium. Little to no methylation is observed in non-tumor tissue areas.
  
  
  CONCLUSIONS
  We applied an accurate microdissection technique to isolate endothelial cells from tissues, enabling DNA analysis such as promoter methylation status. The observations suggest that epigenetic alterations may play a role in determining the phenotype of tumor-associated vasculature.
authors.affiliation: Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA. grovera@mail.nih.gov
authors.forename: Amelia C
authors.initials: AC
authors.lastname: Grover
authors.forename: Michael A
authors.initials: MA
authors.lastname: Tangrea
authors.forename: Karen G
authors.initials: KG
authors.lastname: Woodson
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Wallis
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Hanson
authors.forename: Rodrigo F
authors.initials: RF
authors.lastname: Chuaqui
authors.forename: John W
authors.initials: JW
authors.lastname: Gillespie
authors.forename: Heidi S
authors.initials: HS
authors.lastname: Erickson
authors.forename: Robert F
authors.initials: RF
authors.lastname: Bonner
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Pohida
authors.forename: Michael R
authors.initials: MR
authors.lastname: Emmert-Buck
authors.forename: Steven K
authors.initials: SK
authors.lastname: Libutti