title: Mechanisms of CHD5 Inactivation in neuroblastomas.
abstract: OBJECTIVE
  Neuroblastomas (NBs) have genomic, biological, and clinical heterogeneity. High-risk NBs are characterized by several genomic changes, including MYCN amplification and 1p36 deletion. We identified the chromatin-remodeling gene CHD5 as a tumor suppressor gene that maps to 1p36.31. Low or absent CHD5 expression is associated with a 1p36 deletion and an unfavorable outcome, but the mechanisms of CHD5 inactivation in NBs are unknown.
  
  
  METHODS
  We examined (i) the CHD5 sequence in 188 high-risk NBs investigated through the TARGET initiative, (ii) the methylation status of the CHD5 promoter in 108 NBs with or without 1p36 deletion and/or MYCN amplification, and (iii) mRNA expression of CHD5 and MYCN in 814 representative NBs using TaqMan low-density array microfluidic cards.
  
  
  RESULTS
  We found no examples of somatically acquired CHD5 mutations, even in cases with 1p36 deletion, indicating that homozygous genomic inactivation is rare. Methylation of the CHD5 promoter was common in the high-risk tumors, and it was generally associated with both 1p deletion and MYCN amplification. High CHD5 expression was a powerful predictor of favorable outcome, and it showed prognostic value even in multivariable analysis after adjusting for MYCN amplification, 1p36 deletion, and/or 11q deletion.
  
  
  CONCLUSIONS
  We conclude that (i) somatically acquired CHD5 mutations are rare in primary NBs, so inactivation probably occurs by deletion and epigenetic silencing; (ii) CHD5 expression and promoter methylation are associated with MYCN amplification, suggesting a possible interaction between these 2 genes; and (iii) high CHD5 expression is strongly correlated with favorable clinical/biological features and outcome.
authors.affiliation: Division of Oncology, the Children's Hospital of Philadelphia, Philadelphia, PA, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Koyama
authors.forename: Tiangang
authors.initials: T
authors.lastname: Zhuang
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Light
authors.forename: Venkatadri
authors.initials: V
authors.lastname: Kolla
authors.forename: Mayumi
authors.initials: M
authors.lastname: Higashi
authors.forename: Patrick W
authors.initials: PW
authors.lastname: McGrady
authors.forename: Wendy B
authors.initials: WB
authors.lastname: London
authors.forename: Garrett M
authors.initials: GM
authors.lastname: Brodeur
mesh_terms: D045744:Cell Line, Tumor; D002648:Child; D002675:Child, Preschool; D002878:Chromosomes, Human, Pair 1; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D006801:Humans; D007223:Infant; D000071447:N-Myc Proto-Oncogene Protein; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009447:Neuroblastoma / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D015513:Oncogene Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D017384:Sequence Deletion; D014162:Transfection
chemical_list: C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D012333:RNA, Messenger; D004265:DNA Helicases; C471926:CHD5 protein, human