title: MYCN sensitizes human neuroblastoma to apoptosis by HIPK2 activation through a DNA damage response.
abstract: MYCN amplification occurs in approximately 20% of human neuroblastomas and is associated with early tumor progression and poor outcome, despite intensive multimodal treatment. However, MYCN overexpression also sensitizes neuroblastoma cells to apoptosis. Thus, uncovering the molecular mechanisms linking MYCN to apoptosis might contribute to designing more efficient therapies for MYCN-amplified tumors. Here we show that MYCN-dependent sensitization to apoptosis requires activation of p53 and its phosphorylation at serine 46. The p53(S46) kinase HIPK2 accumulates on MYCN expression, and its depletion by RNA interference impairs p53(S46) phosphorylation and apoptosis. Remarkably, MYCN induces a DNA damage response that accounts for the inhibition of HIPK2 degradation through an ATM- and NBS1-dependent pathway. Prompted by the rare occurrence of p53 mutations and by the broad expression of HIPK2 in our human neuroblastoma series, we evaluated the effects of the p53-reactivating compound Nutlin-3 on this pathway. At variance from other tumor histotypes, in MYCN-amplified neuroblastoma, Nutlin-3 further induced HIPK2 accumulation, p53(S46) phosphorylation, and apoptosis, and in combination with clastogenic agents purged virtually the entire cell population. Altogether, our data uncover a novel mechanism linking MYCN to apoptosis that can be triggered by the p53-reactivating compound Nutlin-3, supporting its use in the most difficult-to-treat subset of neuroblastoma.
authors.affiliation: Department of Experimental Medicine, Sapienza University of Rome, Policlinico Umberto I, Viale Regina Elena, 324, 00161, Rome, Italy.
authors.forename: Marialaura
authors.initials: M
authors.lastname: Petroni
authors.forename: Veronica
authors.initials: V
authors.lastname: Veschi
authors.forename: Andrea
authors.initials: A
authors.lastname: Prodosmo
authors.forename: Cinzia
authors.initials: C
authors.lastname: Rinaldo
authors.forename: Isabella
authors.initials: I
authors.lastname: Massimi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Carbonari
authors.forename: Carlo
authors.initials: C
authors.lastname: Dominici
authors.forename: Heather P
authors.initials: HP
authors.lastname: McDowell
authors.forename: Christian
authors.initials: C
authors.lastname: Rinaldi
authors.forename: Isabella
authors.initials: I
authors.lastname: Screpanti
authors.forename: Luigi
authors.initials: L
authors.lastname: Frati
authors.forename: Armando
authors.initials: A
authors.lastname: Bartolazzi
authors.forename: Alberto
authors.initials: A
authors.lastname: Gulino
authors.forename: Silvia
authors.initials: S
authors.lastname: Soddu
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Giannini
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D064007:Ataxia Telangiectasia Mutated Proteins; D001761:Bleomycin / Q000494:pharmacology; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009154:Mutation; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012694:Serine / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; C112156:NBN protein, human; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D001761:Bleomycin; D012694:Serine; C115114:HIPK2 protein, human; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases