title: CpG hypermethylation of the UCHL1 gene promoter is associated with pathogenesis and poor prognosis in renal cell carcinoma.
abstract: OBJECTIVE
  Aberrant DNA hypermethylation has been reported in renal cell carcinoma. We performed microarray analysis in the renal cancer cell line ACHN treated with the demethylating agent 5-aza-2'-deoxycytidine and investigated the UCHL1 gene involved in the regulation of cellular ubiquitin levels.
  
  
  METHODS
  We subjected 131 renal cell carcinoma and 61 corresponding normal kidney tissue samples to real-time reverse transcriptase-polymerase chain reaction, quantitative methylation specific polymerase chain reaction and immunohistochemistry. We also established a stable UCHL1 transfectant to evaluate cell growth.
  
  
  RESULTS
  We identified 10 genes that were up-regulated more than 2.5-fold in 5-aza-2'-deoxycytidine treated vs untreated ACHN cells. UCHL1 expression was increased 3.41-fold by 5-aza-2'-deoxycytidine treatment. In clinical samples the UCHL1 methylation index was significantly higher in renal cell carcinoma than in normal kidney tissue (p = 0.011). Conversely UCHL1 mRNA expression was significantly lower in renal cell carcinoma than in normal kidney tissue (p <0.0001). There was a negative correlation between mRNA expression and the UCHL1 methylation index (p = 0.017). The immunostaining score for UCHL1 was significantly higher in normal kidney tissue than in renal cell carcinoma (p <0.0001). Kaplan-Meier analysis showed that a positive UCHL1 methylation index had a significant adverse effect on prognosis (p = 0.048). Significant growth inhibition in UCHL1 transfectant compared to that in WT ACHN (p <0.0001) suggests that UCHL1 functions as a potential tumor suppressor gene in human renal cell carcinoma.
  
  
  CONCLUSIONS
  To our knowledge we report the first study demonstrating that the mechanism of UCHL1 down-regulation in renal cell carcinoma is through CpG hypermethylation of the promoter region and methylation of the UCHL1 gene is associated with a poor prognosis in patients with renal cell carcinoma.
authors.affiliation: Department of Urology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kagara
authors.forename: Hideki
authors.initials: H
authors.lastname: Enokida
authors.forename: Kazumori
authors.initials: K
authors.lastname: Kawakami
authors.forename: Ryouichirou
authors.initials: R
authors.lastname: Matsuda
authors.forename: Kazuki
authors.initials: K
authors.lastname: Toki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nishimura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Chiyomaru
authors.forename: Shuichi
authors.initials: S
authors.lastname: Tatarano
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Itesako
authors.forename: Ken
authors.initials: K
authors.lastname: Kawamoto
authors.forename: Kenryu
authors.initials: K
authors.lastname: Nishiyama
authors.forename: Naohiko
authors.initials: N
authors.lastname: Seki
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nakagawa
mesh_terms: D002292:Carcinoma, Renal Cell / Q000235:genetics*; D045744:Cell Line, Tumor; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics*; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D043222:Ubiquitin Thiolesterase / Q000235:genetics*
chemical_list: C482860:UCHL1 protein, human; D043222:Ubiquitin Thiolesterase