title: p53 Loss in MYC-Driven Neuroblastoma Leads to Metabolic Adaptations Supporting Radioresistance.
abstract: Neuroblastoma is the most common childhood extracranial solid tumor. In high-risk cases, many of which are characterized by amplification of MYCN, outcome remains poor. Mutations in the p53 (TP53) tumor suppressor are rare at diagnosis, but evidence suggests that p53 function is often impaired in relapsed, treatment-resistant disease. To address the role of p53 loss of function in the development and pathogenesis of high-risk neuroblastoma, we generated a MYCN-driven genetically engineered mouse model in which the tamoxifen-inducible p53ER(TAM) fusion protein was expressed from a knock-in allele (Th-MYCN/Trp53(KI)). We observed no significant differences in tumor-free survival between Th-MYCN mice heterozygous for Trp53(KI) (n = 188) and Th-MYCN mice with wild-type p53 (n = 101). Conversely, the survival of Th-MYCN/Trp53(KI/KI) mice lacking functional p53 (n = 60) was greatly reduced. We found that Th-MYCN/Trp53(KI/KI) tumors were resistant to ionizing radiation (IR), as expected. However, restoration of functional p53ER(TAM) reinstated sensitivity to IR in only 50% of Th-MYCN/Trp53(KI/KI) tumors, indicating the acquisition of additional resistance mechanisms. Gene expression and metabolic analyses indicated that the principal acquired mechanism of resistance to IR in the absence of functional p53 was metabolic adaptation in response to chronic oxidative stress. Tumors exhibited increased antioxidant metabolites and upregulation of glutathione S-transferase pathway genes, including Gstp1 and Gstz1, which are associated with poor outcome in human neuroblastoma. Accordingly, glutathione depletion by buthionine sulfoximine together with restoration of p53 activity resensitized tumors to IR. Our findings highlight the complex pathways operating in relapsed neuroblastomas and the need for combination therapies that target the diverse resistance mechanisms at play. Cancer Res; 76(10); 3025-35. ©2016 AACR.
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Orli
authors.initials: O
authors.lastname: Yogev
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Karen
authors.initials: K
authors.lastname: Barker
authors.affiliation: Department of Surgery and Cancer, Imperial College, London, United Kingdom.
authors.forename: Arti
authors.initials: A
authors.lastname: Sikka
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom. Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Gilberto S
authors.initials: GS
authors.lastname: Almeida
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Albert
authors.initials: A
authors.lastname: Hallsworth
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Smith
authors.affiliation: Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Yann
authors.initials: Y
authors.lastname: Jamin
authors.affiliation: Division of Cancer Therapeutics, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Ruth
authors.initials: R
authors.lastname: Ruddle
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Alexander
authors.initials: A
authors.lastname: Koers
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Hannah T
authors.initials: HT
authors.lastname: Webber
authors.affiliation: Division of Cancer Therapeutics, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Florence I
authors.initials: FI
authors.lastname: Raynaud
authors.affiliation: Division of Cancer Therapeutics, The Institute of Cancer Research, London, United Kingdom. Department of Molecular Pathology, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Sergey
authors.initials: S
authors.lastname: Popov
authors.affiliation: Division of Cancer Therapeutics, The Institute of Cancer Research, London, United Kingdom. Department of Molecular Pathology, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Jones
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Kevin
authors.initials: K
authors.lastname: Petrie
authors.affiliation: Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Robinson
authors.affiliation: Department of Surgery and Cancer, Imperial College, London, United Kingdom.
authors.forename: Hector C
authors.initials: HC
authors.lastname: Keun
authors.affiliation: Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom. louis.chesler@icr.ac.uk.
authors.forename: Louis
authors.initials: L
authors.lastname: Chesler
mesh_terms: D000222:Adaptation, Physiological / Q000528:radiation effects*; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D015153:Blotting, Western; D049109:Cell Proliferation / Q000528:radiation effects; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D000071447:N-Myc Proto-Oncogene Protein / Q000502:physiology*; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology* / Q000532:radiotherapy; D012333:RNA, Messenger / Q000235:genetics; D011836:Radiation Tolerance; D011839:Radiation, Ionizing; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
chemical_list: C571825:MYCN protein, mouse; D000071447:N-Myc Proto-Oncogene Protein; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53