title: IGFBP3 impedes aggressive growth of pediatric liver cancer and is epigenetically silenced in vascular invasive and metastatic tumors.
abstract: BACKGROUND
  Hepatoblastoma (HB) is an embryonal liver neoplasm of early childhood with a poor prognosis for patients with distant metastases and vascular invasion. We and others have previously shown that the overexpression of insulin-like growth factor 2 (IGF2), loss of imprinting at the IGF2/H19 locus, and amplification of pleomorphic adenoma gene 1 (PLAG1) are common features in HB, suggesting a critical role of the IGF axis in hepatoblastomagenesis. In this study, we investigated the role of the insulin-like growth factor binding protein 3 (IGFBP3), a known competitor of the IGF axis, in pediatric liver cancers.
  
  
  RESULTS
  The IGFBP3 gene was highly expressed in normal pediatric livers but was heavily downregulated in four HB cell lines and the majority of HB primary tumors (26/36). Detailed methylation analysis of CpG sites in the IGFBP3 promoter region by bisulfite sequencing revealed a high degree of DNA methylation, which is causatively associated with the suppression of IGFBP3 in HB cell lines. Consequently, the treatment of HB cell lines with 5-aza-2'-deoxycytidine resulted in DNA demethylation and reactivation of the epigenetically silenced IGFBP3 expression. Interestingly, IGFBP3 promoter methylation predominantly occurred in metastatic HB with vascular invasion. Restoring IGFBP3 expression in HB cells resulted in reduced colony formation, migration, and invasion.
  
  
  CONCLUSIONS
  This study provides the first direct evidence that the reactivation of IGFBP3 decreases aggressive properties of pediatric liver cancer cells and that IGFBP3 promoter methylation might be used as an indicator for vessel-invasive tumor growth in HB patients.
authors.affiliation: Department of Pediatric Surgery, Dr, von Hauner Children's Hospital, Ludwig-Maximilians-University Munich, 80337 Munich, Federal Republic of Germany.
authors.forename: Ivonne
authors.initials: I
authors.lastname: Regel
authors.forename: Melanie
authors.initials: M
authors.lastname: Eichenmüller
authors.forename: Saskia
authors.initials: S
authors.lastname: Joppien
authors.forename: Johanna
authors.initials: J
authors.lastname: Liebl
authors.forename: Beate
authors.initials: B
authors.lastname: Häberle
authors.forename: Josef
authors.initials: J
authors.lastname: Müller-Höcker
authors.forename: Angelika
authors.initials: A
authors.lastname: Vollmar
authors.forename: Dietrich
authors.initials: D
authors.lastname: von Schweinitz
authors.forename: Roland
authors.initials: R
authors.lastname: Kappler
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics / Q000502:physiology; D002470:Cell Survival / Q000235:genetics / Q000502:physiology; D044127:Epigenesis, Genetic / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics*; D008113:Liver Neoplasms / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3