Methylation of a panel of microRNA genes is a novel biomarker for detection of bladder cancer

Eur Urol. 2013 Jun;63(6):1091-100. doi: 10.1016/j.eururo.2012.11.030. Epub 2012 Nov 23.


Background: Dysregulation of microRNAs (miRNAs) has been implicated in bladder cancer (BCa), although the mechanism is not fully understood.

Objective: We aimed to explore the involvement of epigenetic alteration of miRNA expression in BCa.

Design, setting, and participants: Two BCa cell lines (T24 and UM-UC-3) were treated with 5-aza-2'-deoxycytidine (5-aza-dC) and 4-phenylbutyric acid (PBA), after which their miRNA expression profiles were analyzed using a TaqMan array (Life Technologies, Carlsbad, CA, USA). Bisulfite pyrosequencing was used to assess miRNA gene methylation in 5 cancer cell lines, 83 primary tumors, and 120 preoperative and 47 postoperative urine samples.

Outcome measurements and statistical analysis: Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic performance of the miRNA gene panel.

Results and limitations: Of 664 miRNAs examined, 146 were upregulated by 5-aza-dC plus PBA. CpG islands were identified in the proximal upstream of 23 miRNA genes, and 12 of those were hypermethylated in cell lines. Among them, miR-137, miR-124-2, miR-124-3, and miR-9-3 were frequently and tumor-specifically methylated in primary cancers (miR-137: 68.7%; miR-124-2: 50.6%; miR-124-3: 65.1%; miR-9-3: 45.8%). Methylation of the same four miRNAs in urine specimens enabled BCa detection with 81% sensitivity and 89% specificity; the area under the ROC curve was 0.916. Ectopic expression of silenced miRNAs in BCa cells suppressed growth and cell invasion.

Conclusions: Our results indicate that epigenetic silencing of miRNA genes may be involved in the development of BCa and that methylation of miRNA genes could be a useful biomarker for cancer detection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / urine
  • Carcinoma, Transitional Cell / diagnosis
  • Carcinoma, Transitional Cell / genetics*
  • Carcinoma, Transitional Cell / urine
  • Cell Line, Tumor
  • CpG Islands
  • DNA Methylation*
  • Epigenesis, Genetic
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic*
  • Gene Silencing
  • Humans
  • Male
  • MicroRNAs / genetics*
  • MicroRNAs / urine
  • Middle Aged
  • ROC Curve
  • Real-Time Polymerase Chain Reaction
  • Sensitivity and Specificity
  • Urinary Bladder Neoplasms / diagnosis
  • Urinary Bladder Neoplasms / genetics*
  • Urinary Bladder Neoplasms / urine


  • Biomarkers, Tumor
  • MicroRNAs