title: Dickkopf-1 is down-regulated by MYCN and inhibits neuroblastoma cell proliferation.
abstract: Neuroblastomas are tumors of the developing peripheral sympathetic nervous system, which originates from the neural crest. Twenty percent of neuroblastomas show amplification of the MYCN oncogene, which correlates with poor prognosis. The MYCN transcription factor can activate and repress gene expression. To broaden our insight in the spectrum of genes down-regulated by MYCN, we generated gene expression profiles of the neuroblastoma cell lines SHEP-21N and SKNAS-NmycER, in which MYCN activity can be regulated. In this study, we show that MYCN suppresses the expression of Dickkopf-1 (DKK1) in both cell lines. DKK1 is a potent inhibitor of the wnt/beta-catenin signalling cascade, which is known to function in neural crest cell migration. We generated a DKK1 inducible cell line, IMR32-DKK1, which showed impaired proliferation upon DKK1 expression. Surprisingly, DKK1 expression did not inhibit the canonical wnt/beta-catenin signalling, suggesting a role of DKK1 in an alternative route of the wnt pathway. Gene expression profiling of two IMR32-DKK1 clones showed that only a few genes, amongst which SYNPO2, were up-regulated by DKK1. SYNPO2 encodes an actin-binding protein and was previously found to inhibit proliferation and invasiveness of prostate cancer cells. These results suggest that MYCN might stimulate cell proliferation by inhibiting the expression of DKK1. DKK1 might exert part of its growth suppressive effect by induction of SYNPO2 expression.
authors.affiliation: Department of Human Genetics, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands.
authors.forename: Arjen
authors.initials: A
authors.lastname: Koppen
authors.forename: Rachida
authors.initials: R
authors.lastname: Ait-Aissa
authors.forename: Saskia
authors.initials: S
authors.lastname: Hopman
authors.forename: Jan
authors.initials: J
authors.lastname: Koster
authors.forename: Franciska
authors.initials: F
authors.lastname: Haneveld
authors.forename: Rogier
authors.initials: R
authors.lastname: Versteeg
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Valentijn
mesh_terms: D049109:Cell Proliferation; D015536:Down-Regulation; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008840:Microfilament Proteins / Q000378:metabolism; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D013997:Time Factors; D014162:Transfection; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
chemical_list: C495270:CTNNB1 protein, human; C501126:DKK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; C459801:MYCN protein, human; D008840:Microfilament Proteins; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D012333:RNA, Messenger; C503979:SYNPO2 protein, human; D051153:Wnt Proteins; D051176:beta Catenin