title: Two independent epigenetic biomarkers predict survival in neuroblastoma.
abstract: BACKGROUND
  Neuroblastoma (NB) is the most common extracranial pediatric solid tumor with a highly variable clinical course, ranging from spontaneous regression to life-threatening disease. Survival rates for high-risk NB patients remain disappointingly low despite multimodal treatment. Thus, there is an urgent clinical need for additional biomarkers to improve risk stratification, treatment management, and survival rates in children with aggressive NB.
  
  
  RESULTS
  Using gene promoter methylation analysis in 48 neuroblastoma tumors with microarray technology, we found a strong association between survival and gene promoter hypermethylation (P = 0.036). Hypermethylation of 70 genes significantly differentiated high-risk survivor patients from those who died during follow-up time. Sixteen genes with relevant roles in cancer biology were further validated in an additional cohort of 83 neuroblastoma tumors by bisulfite pyrosequencing. High promoter methylation rates of these genes were found in patients with metastatic tumors (either stage metastatic (M) or metastatic special (MS)), 18 months or older at first diagnosis, MYCN amplification, relapsed, and dead. Notably, the degree of methylation of retinoblastoma 1 (RB1) and teratocarcinoma-derived growth factor 1 (TDGF1) predicts event-free and overall survival independently of the established risk factors. In addition, low RB1 mRNA expression levels associate with poor prognosis suggesting that promoter methylation could contribute to the transcriptional silencing of this gene in NB.
  
  
  CONCLUSIONS
  We found a new epigenetic signature predictive for NB patients' outcome: the methylation status of RB1 and TDGF1 associate with poorer survival. This information is useful to assess prognosis and improve treatment selection.
authors.affiliation: Pediatric Oncology Unit, Hospital Universitari i Politècnic La Fe, Avda Fernando Abril Martorell, Valencia, 46026 Spain.
authors.forename: Yania
authors.initials: Y
authors.lastname: Yáñez
authors.affiliation: Pediatric Oncology Unit, Hospital Universitari i Politècnic La Fe, Avda Fernando Abril Martorell, Valencia, 46026 Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Grau
authors.affiliation: Chromatin and Disease Group, Cancer Epigenetics and Biology Programme (PEBC) Bellvitge Biomedical Research Institute (IDIBELL), Gran Via de L'Hospitalet, Barcelona, 08908 Spain.
authors.forename: Virginia C
authors.initials: VC
authors.lastname: Rodríguez-Cortez
authors.affiliation: Biostatistics Unit, Instituto de Investigación Sanitaria La Fe, Avda Fernando Abril Martorell, Valencia, 46026 Spain.
authors.forename: David
authors.initials: D
authors.lastname: Hervás
authors.affiliation: Genomics of Gene Expression Lab, Centro de Investigaciones Príncipe Felipe, Carrer d'Eduardo Primo Yúfera, Valencia, 46012 Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Vidal
authors.affiliation: Department of Pathology, Medical School, University of Valencia, Avda Blasco Ibáñez, Valencia, 46010 Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Noguera
authors.affiliation: Department of Pathology, Hospital Universitari i Politècnic La Fe, Avda Fernando Abril Martorell, Valencia, 46026 Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Hernández
authors.affiliation: Pediatric Oncology Unit, Hospital Universitari i Politècnic La Fe, Avda Fernando Abril Martorell, Valencia, 46026 Spain.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Segura
authors.affiliation: Pediatric Oncology Unit, Hospital Universitari i Politècnic La Fe, Avda Fernando Abril Martorell, Valencia, 46026 Spain.
authors.forename: Adela
authors.initials: A
authors.lastname: Cañete
authors.affiliation: Genomics of Gene Expression Lab, Centro de Investigaciones Príncipe Felipe, Carrer d'Eduardo Primo Yúfera, Valencia, 46012 Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Conesa
authors.affiliation: Laboratory of Cellular and Molecular Biology, Instituto de Investigación Sanitaria La Fe, Avda Fernando Abril Martorell, Valencia, 46026 Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Font de Mora
authors.affiliation: Pediatric Oncology Unit, Hospital Universitari i Politècnic La Fe, Avda Fernando Abril Martorell, Valencia, 46026 Spain.
authors.forename: Victoria
authors.initials: V
authors.lastname: Castel
keywords: Epigenetic biomarkers; Neuroblastoma; Promoter methylation