title: Serum DNA hypermethylation in patients with kidney cancer: results of a prospective study.
abstract: OBJECTIVE
  No reliable biomarker for renal cell carcinoma (RCC) exists. The purpose of this study was to analyze the value of CpG island hypermethylation of cell-free (cf) circulating serum DNA in patients with RCC as a potential biomarker.
  
  
  METHODS
  In total 35 patients with RCC and 54 healthy individuals were enrolled in this study. Cell-free DNA (cFDNA) in serum was isolated and digested with methylation-sensitive restriction enzymes (Bsh1236I, HpaII and HinP1I) to quantify the amount of methylated Adenomatosis-poliposis-coli gene (APC), Gluthation-a-transferase-protein 1 gene (GSTP1), ARF tumor suppressor protein gene (p14(ARF)), cyclin-dependent kinase inhibitor 2A (p16), Retinoid-acid-receptor-beta gene (RAR-B), RAS-association domain family-1 gene (RASSF1), Tissue inhibitor of metalloproteinase-gene (TIMP3) and Prostaglandin-endoperoxid synthase 2 (PTGS2) DNA fragments.
  
  
  RESULTS
  In 30 of 35 investigated patients with RCC, at least one gene was methylated within the serum cfDNA. The methylation frequency ranged from 14.3% for p14(ARF) to 54.3% for APC. All genes, except p16 and TIMP3, were significantly more frequently methylated in patients with RCC compared to healthy individuals. Receiver operator characteristic analysis showed a high specificity for serum cfDNA methylation [between 85.2% for RAR-B and 100% for p14(ARF)], but the sensitivity was low in single-gene analysis [range-14.3% for p14(ARF) to 54.3% for APC]. The combined analysis of multiple genes increased the diagnostic sensitivity (i.e. APC, PTGS2 and GSTP1, 62.9%) at a high specificity (87%). DNA hypermethylation of APC was correlated with advanced tumor stage.
  
  
  CONCLUSIONS
  The detection of hypermethylated cfDNA in serum may be helpful for the identification of RCC; the combinatorial analysis of multiple genes may increase the diagnostic accuracy.
authors.affiliation: Department of Urology, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany. Stefan.Hauser@uni-bonn.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Hauser
authors.forename: Tobias
authors.initials: T
authors.lastname: Zahalka
authors.forename: Guido
authors.initials: G
authors.lastname: Fechner
authors.forename: Stefan C
authors.initials: SC
authors.lastname: Müller
authors.forename: Jörg
authors.initials: J
authors.lastname: Ellinger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D002292:Carcinoma, Renal Cell / Q000097:blood* / Q000175:diagnosis / Q000235:genetics; D016022:Case-Control Studies; D018899:CpG Islands; D004247:DNA / Q000097:blood* / Q000235:genetics; D019175:DNA Methylation; D005260:Female; D052138:Genes, Neoplasm; D006801:Humans; D007680:Kidney Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000235:genetics; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D004247:DNA
keywords: Cell-free DNA; CpG-island; biomarker; hypermethylation; kidney cancer; serum