title: MYCN-regulated microRNAs repress estrogen receptor-alpha (ESR1) expression and neuronal differentiation in human neuroblastoma.
abstract: MYCN, a proto-oncogene normally expressed in the migrating neural crest, is in its amplified state a key factor in the genesis of human neuroblastoma (NB). However, the mechanisms underlying MYCN-mediated NB progression are poorly understood. Here, we present a MYCN-induced miRNA signature in human NB involving the activation and transrepression of several miRNA genes from paralogous clusters. Several family members derived from the miR-17 approximately 92 cluster, including miR-18a and miR-19a, were among the up-regulated miRNAs. Expression analysis of these miRNAs in NB tumors confirmed increased levels in MYCN-amplified samples. Specifically, we show that miR-18a and miR-19a target and repress the expression of estrogen receptor-alpha (ESR1), a ligand-inducible transcription factor implicated in neuronal differentiation. Immunohistochemical staining demonstrated ESR1 expression in human fetal sympathetic ganglia, suggesting a role for ESR1 during sympathetic nervous system development. Concordantly, lentiviral restoration of ESR1 in NB cells resulted in growth arrest and neuronal differentiation. Moreover, lentiviral-mediated inhibition of miR-18a in NB cells led to severe growth retardation, outgrowth of varicosity-containing neurites, and induction of neuronal sympathetic differentiation markers. Bioinformatic analyses of microarray data from NB tumors revealed that high ESR1 expression correlates with increased event-free survival in NB patients and favorable disease outcome. Thus, MYCN amplification may disrupt estrogen signaling sensitivity in primitive sympathetic cells through deregulation of ESR1, thereby preventing the normal induction of neuroblast differentiation. Collectively, our findings demonstrate the molecular consequences of abnormal miRNA transcription in a MYCN-driven tumor and offer unique insights into the pathology underlying MYCN-amplified NB.
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: Jakob
authors.initials: J
authors.lastname: Lovén
authors.forename: Nikolay
authors.initials: N
authors.lastname: Zinin
authors.forename: Therese
authors.initials: T
authors.lastname: Wahlström
authors.forename: Inga
authors.initials: I
authors.lastname: Müller
authors.forename: Petter
authors.initials: P
authors.lastname: Brodin
authors.forename: Erik
authors.initials: E
authors.lastname: Fredlund
authors.forename: Ulf
authors.initials: U
authors.lastname: Ribacke
authors.forename: Andor
authors.initials: A
authors.lastname: Pivarcsi
authors.forename: Sven
authors.initials: S
authors.lastname: Påhlman
authors.forename: Marie
authors.initials: M
authors.lastname: Henriksson
mesh_terms: D020413:3' Untranslated Regions; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D020413:3' Untranslated Regions; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; C000715470:MAS1 protein, human; C459801:MYCN protein, human; D035683:MicroRNAs; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D000090063:Proto-Oncogene Mas