title: Methylation of the RASSF1A promoter is predictive of poor outcome among patients with Wilms tumor.
abstract: BACKGROUND
  Wilms tumor (WT) has a survival rate of 90% following multimodality therapy. Nevertheless, there are some groups of patients with event-free survival rates less than 75%. In addition to clinical prognostic factors, loss of heterozygosity at 1p and/or 16q has been used to determine treatment intensity. However, the incidence of this abnormality is low, and new biomarkers are still needed.
  
  
  METHODS
  We analyzed methylation status of three tumor suppressor genes; Ras-association domain family 1 protein, isoform A (RASSF1A), DCR2, and CASP8, in 84 WTs using conventional methylation-specific PCR (cMSP), and the results were correlated with outcome. Furthermore, we analyzed the methylation status of RASSF1A by quantitative MSP (qMSP) in 171 WTs, and evaluated clinical and genetic differences between the methylated and unmethylated tumors.
  
  
  RESULTS
  RASSF1A was the most frequently methylated gene identified by cMSP, and associated with a poor outcome. Patients with a RASSF1A-methylated tumor had shorter overall and event-free survival periods (P = 0.043 and 0.018, respectively), when a cut-off value of 7% by qMSP was used. The methylation was more frequent in tumors of older children than younger children (P < 0.001), and in advanced-stage tumors than early stage tumors (P = 0.001). However, multivariate analysis could not confirm the prognostic significance of RASSF1A methylation, possibly because of a small number of advanced stage tumors examined. RASSF1A methylation was correlated with LOH at 1p and/or 16q (P = 0.017), but not with WT1 abnormality, suggesting the methylation and LOH to involve the same tumorigenic pathway.
  
  
  CONCLUSIONS
  The methylation status of RASSF1A might be a novel biomarker to predict outcome of WT patients.
authors.affiliation: Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Saitama, Japan.
authors.forename: Junjiro
authors.initials: J
authors.lastname: Ohshima
authors.forename: Masayuki
authors.initials: M
authors.lastname: Haruta
authors.forename: Yuiko
authors.initials: Y
authors.lastname: Fujiwara
authors.forename: Naoki
authors.initials: N
authors.lastname: Watanabe
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Arai
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ariga
authors.forename: Hajime
authors.initials: H
authors.lastname: Okita
authors.forename: Tsugumichi
authors.initials: T
authors.lastname: Koshinaga
authors.forename: Takaharu
authors.initials: T
authors.lastname: Oue
authors.forename: Shiro
authors.initials: S
authors.lastname: Hinotsu
authors.forename: Hisaya
authors.initials: H
authors.lastname: Nakadate
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Horie
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fukuzawa
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kaneko
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D002648:Child; D019175:DNA Methylation; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D011379:Prognosis; D011401:Promoter Regions, Genetic; D016896:Treatment Outcome; D025521:Tumor Suppressor Proteins / Q000235:genetics*; D009396:Wilms Tumor / Q000235:genetics* / Q000401:mortality
chemical_list: D014408:Biomarkers, Tumor; C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins