title: Dickkopf-3 is regulated by the MYCN-induced miR-17-92 cluster in neuroblastoma.
abstract: Neuroblastoma (NB) is a paediatric tumour with a remarkable diverse clinical behaviour. Approximately half of the high stage aggressive tumours are characterized by MYCN gene amplification but our understanding of the role of MYCN in NB oncogenesis is incomplete. Previous studies have shown that MYCN expression is inversely correlated with expression of Dickkopf-3 (DKK3), a gene encoding an extracellular protein with presumed tumour suppressor activity, but direct MYCN regulation of DKK3 was excluded leaving the mechanism of regulation unexplained. Given the recently established role of MYCN-regulated miRNAs in downregulation of protein-coding genes and predicted seeds for miR-17-92 cluster members within the DKK3 3'UTR, we hypothesized that this mechanism would act in MYCN regulation of DKK3. To investigate this, we used a validated miR-17-92-inducible cellular system and could demonstrate robust downregulation of DKK3 mRNA and protein levels upon miR-17-92 overexpression. Next, two of the three predicted miRNAs, miR-19b and miR-92a, were shown to lower DKK3 protein levels, in addition to measurable DKK3 mRNA knock-down by miR-92a. Direct interaction between miR-19b or miR-92a and the 3'UTR of DKK3 was validated using luciferase reporter assays. In conclusion, this study demonstrates that the MYCN-induced downregulation of DKK3 results from direct upregulation of miR-17-92 components effecting both DKK3 mRNA stability and translation which further contributes to the pleiotropic oncogenic effect of elevated MYCN levels. The strict MYCN-mediated regulation of DKK3 is suggestive for an important downstream function of the MYCN protein and thus warrants further investigations to unravel the role of DKK3 in NB.
authors.affiliation: Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
authors.forename: Sara
authors.initials: S
authors.lastname: De Brouwer
authors.forename: Pieter
authors.initials: P
authors.lastname: Mestdagh
authors.forename: Irina
authors.initials: I
authors.lastname: Lambertz
authors.forename: Filip
authors.initials: F
authors.lastname: Pattyn
authors.forename: Anne
authors.initials: A
authors.lastname: De Paepe
authors.forename: Frank
authors.initials: F
authors.lastname: Westermann
authors.forename: Christina
authors.initials: C
authors.lastname: Schroeder
authors.forename: Johannes H
authors.initials: JH
authors.lastname: Schulte
authors.forename: Alexander
authors.initials: A
authors.lastname: Schramm
authors.forename: Katleen
authors.initials: K
authors.lastname: De Preter
authors.forename: Jo
authors.initials: J
authors.lastname: Vandesompele
authors.forename: Frank
authors.initials: F
authors.lastname: Speleman
mesh_terms: D020413:3' Untranslated Regions; D048868:Adaptor Proteins, Signal Transducing; D045744:Cell Line, Tumor; D018925:Chemokines; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D035683:MicroRNAs / Q000032:analysis / Q000502:physiology*; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000209:etiology / Q000235:genetics*; D009687:Nuclear Proteins / Q000502:physiology*; D015513:Oncogene Proteins / Q000502:physiology*; D062085:RNA, Long Noncoding; D015854:Up-Regulation
chemical_list: D020413:3' Untranslated Regions; D048868:Adaptor Proteins, Signal Transducing; D018925:Chemokines; C498624:DKK3 protein, human; D036341:Intercellular Signaling Peptides and Proteins; C568997:MIR17HG, human; C549214:MIRN19A microRNA, human; C459801:MYCN protein, human; D035683:MicroRNAs; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D062085:RNA, Long Noncoding