title: MYCN gene expression is required for the onset of the differentiation programme in neuroblastoma cells.
abstract: Neuroblastoma is an embryonic tumour of the sympathetic nervous system and is one of the most common cancers in childhood. A high differentiation stage has been associated with a favourable outcome; however, the mechanisms governing neuroblastoma cell differentiation are not completely understood. The MYCN gene is considered the hallmark of neuroblastoma. Even though it has been reported that MYCN has a role during embryonic development, it is needed its decrease so that differentiation can be completed. We aimed to better define the role of MYCN in the differentiation processes, particularly during the early stages. Considering the ability of MYCN to regulate non-coding RNAs, our hypothesis was that N-Myc protein might be necessary to activate differentiation (mimicking embryonic development events) by regulating miRNAs critical for this process. We show that MYCN expression increased in embryonic cortical neural precursor cells at an early stage after differentiation induction. To investigate our hypothesis, we used human neuroblastoma cell lines. In LAN-5 neuroblastoma cells, MYCN was upregulated after 2 days of differentiation induction before its expected downregulation. Positive modulation of various differentiation markers was associated with the increased MYCN expression. Similarly, MYCN silencing inhibited such differentiation, leading to negative modulation of various differentiation markers. Furthermore, MYCN gene overexpression in the poorly differentiating neuroblastoma cell line SK-N-AS restored the ability of such cells to differentiate. We identified three key miRNAs, which could regulate the onset of differentiation programme in the neuroblastoma cells in which we modulated MYCN. Interestingly, these effects were accompanied by changes in the apoptotic compartment evaluated both as expression of apoptosis-related genes and as fraction of apoptotic cells. Therefore, our idea is that MYCN is necessary during the activation of neuroblastoma differentiation to induce apoptosis in cells that are not committed to differentiate.
authors.affiliation: CNR, Institute of Cell Biology and Neurobiology, Rome, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Guglielmi
authors.affiliation: CNR, Institute of Cell Biology and Neurobiology, Rome, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Cinnella
authors.affiliation: CNR, Institute of Cell Biology and Neurobiology, Rome, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Nardella
authors.affiliation: CNR, Institute of Cell Biology and Neurobiology, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Maresca
authors.affiliation: PTV, Laboratory Medicine and Internal Medicine Departments, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Valentini
authors.affiliation: CNR, Institute of Cell Biology and Neurobiology, Rome, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Mercanti
authors.affiliation: CNR, Institute of Cell Biology and Neurobiology, Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Felsani
authors.affiliation: CNR, Institute of Cell Biology and Neurobiology, Rome, Italy.
authors.forename: I
authors.initials: I
authors.lastname: D'Agnano
mesh_terms: D017209:Apoptosis; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D018507:Gene Expression Regulation, Developmental; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism; D000071447:N-Myc Proto-Oncogene Protein; D058953:Neural Stem Cells / Q000378:metabolism; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D013997:Time Factors; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D014408:Biomarkers, Tumor; C534451:MIRN20a microRNA, human; C541874:MIRN92 microRNA, human; C459801:MYCN protein, human; D035683:MicroRNAs; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D014212:Tretinoin