title: MYCN enhances P-gp/MDR1 gene expression in the human metastatic neuroblastoma IGR-N-91 model.
abstract: Despite intensive high-dose chemotherapy and autologous hematopoietic stem cell transplantation, disseminated neuroblastoma (NB) frequently proves to be chemosensitive but not chemocurable, and more often so in NB-presenting MYCN amplification. To assess the direct relationship between the MYCN oncogene and chemoresistance acquisition during NB metastatic dissemination, we have studied MYCN and MDR1 genes using the human IGR-N-91 ectopic xenograft metastatic model. This characterized experimental in vitro model includes human neuroblasts derived from a subcutaneous primary tumor xenograft, disseminated blood cells, myocardium, and bone marrow (BM) metastatic cells. All IGR-N-91-derived neuroblasts harbor a consistent MYCN genomic content but, unlike primary tumor xenograft, BM, and myocardium, human neuroblasts elicit a concomitant increase in MYCN and MDR1 transcripts levels, consistent with chemoresistance phenotype and active P-gp. In contrast, no variation of MRP1 transcript level was associated with the metastatic process in this model. Using an MDR1 promoter-CAT construct, we have shown that the MycN protein activates MDR1 transcription both in exogenous transient MYCN-transfected SK-N-SH cells and in endogenous BM metastatic neuroblasts with an increase in the MYCN transcript level. Band-shift experiments indicate that IGR-N-91 cells enriched with the MycN transcription factor do bind to two E-box motifs localized within the MDR1 promoter. Overall, our data indicate that MYCN overexpression increment contributes to the acquired drug resistance that occurs throughout the NB metastatic process.
authors.affiliation: Centre National de la Recherche Scientifique, Unité Mixte de Recherche (8126), Université Paris-Sud 11, Institut Fédératif de Recherche, Villejuif, France.
authors.forename: Etienne
authors.initials: E
authors.lastname: Blanc
authors.forename: David
authors.initials: D
authors.lastname: Goldschneider
authors.forename: Eric
authors.initials: E
authors.lastname: Ferrandis
authors.forename: Michel
authors.initials: M
authors.lastname: Barrois
authors.forename: Gwenaëlle
authors.initials: G
authors.lastname: Le Roux
authors.forename: Stéphane
authors.initials: S
authors.lastname: Leonce
authors.forename: Sétha
authors.initials: S
authors.lastname: Douc-Rasy
authors.forename: Jean
authors.initials: J
authors.lastname: Bénard
authors.forename: Gilda
authors.initials: G
authors.lastname: Raguénez
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000627:therapeutic use; D002648:Child; D018432:Drug Resistance, Multiple / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D000071447:N-Myc Proto-Oncogene Protein; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D009447:Neuroblastoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins