title: MYC-Driven Neuroblastomas Are Addicted to a Telomerase-Independent Function of Dyskerin.
abstract: The RNA-binding protein dyskerin, encoded by the DKC1 gene, functions as a core component of the telomerase holoenzyme as well as ribonuclear protein complexes involved in RNA processing and ribosome biogenesis. The diverse roles of dyskerin across many facets of RNA biology implicate its potential contribution to malignancy. In this study, we examined the expression and function of dyskerin in neuroblastoma. We show that DKC1 mRNA levels were elevated relative to normal cells across a panel of 15 neuroblastoma cell lines, where both N-Myc and c-Myc directly targeted the DKC1 promoter. Upregulation of MYCN was shown to dramatically increase DKC1 expression. In two independent neuroblastoma patient cohorts, high DKC1 expression correlated strongly with poor event-free and overall survival (P < 0.0001), independently of established prognostic factors. RNAi-mediated depletion of dyskerin inhibited neuroblastoma cell proliferation, including cells immortalized via the telomerase-independent ALT mechanism. Furthermore, dyskerin attenuation impaired anchorage-independent proliferation and tumor growth. Overexpression of the telomerase RNA component, hTR, demonstrated that this proliferative impairment was not a consequence of telomerase suppression. Instead, ribosomal stress, evidenced by depletion of small nucleolar RNAs and nuclear dispersal of ribosomal proteins, was the likely cause of the proliferative impairment in dyskerin-depleted cells. Accordingly, dyskerin suppression caused p53-dependent G1 cell-cycle arrest in p53 wild-type cells, and a p53-independent pathway impaired proliferation in cells with p53 dysfunction. Together, our findings highlight dyskerin as a new therapeutic target in neuroblastoma with crucial telomerase-independent functions and broader implications for the spectrum of malignancies driven by MYC family oncogenes. Cancer Res; 76(12); 3604-17. ©2016 AACR.
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Rosemary
authors.initials: R
authors.lastname: O'Brien
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Sieu L
authors.initials: SL
authors.lastname: Tran
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Michelle F
authors.initials: MF
authors.lastname: Maritz
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Bing
authors.initials: B
authors.lastname: Liu
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Cheng Fei
authors.initials: CF
authors.lastname: Kong
authors.affiliation: Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Purgato
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Chen
authors.initials: C
authors.lastname: Yang
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Jayne
authors.initials: J
authors.lastname: Murray
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Russell
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Claudia L
authors.initials: CL
authors.lastname: Flemming
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Georg
authors.initials: G
authors.lastname: von Jonquieres
authors.affiliation: Telomere Length Regulation Laboratory, Children's Medical Research Institute, Westmead, New South Wales, Australia.
authors.forename: Hilda A
authors.initials: HA
authors.lastname: Pickett
authors.affiliation: Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston, Massachusetts.
authors.forename: Wendy B
authors.initials: WB
authors.lastname: London
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Haber
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas.
authors.forename: Preethi H
authors.initials: PH
authors.lastname: Gunaratne
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Murray D
authors.initials: MD
authors.lastname: Norris
authors.affiliation: Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Perini
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia.
authors.forename: Jamie I
authors.initials: JI
authors.lastname: Fletcher
authors.affiliation: Children's Cancer Institute Australia, Randwick, Sydney, New South Wales, Australia. k.mackenzie@unsw.edu.au.
authors.forename: Karen L
authors.initials: KL
authors.lastname: MacKenzie
mesh_terms: D018797:Cell Cycle Proteins / Q000502:physiology*; D002478:Cells, Cultured; D059585:G1 Phase Cell Cycle Checkpoints; D006801:Humans; D009447:Neuroblastoma / Q000473:pathology*; D009687:Nuclear Proteins / Q000502:physiology*; D016271:Proto-Oncogene Proteins c-myc / Q000502:physiology*; D012270:Ribosomes / Q000502:physiology; D019098:Telomerase / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000502:physiology
chemical_list: D018797:Cell Cycle Proteins; C112148:DKC1 protein, human; D009687:Nuclear Proteins; D016271:Proto-Oncogene Proteins c-myc; D016159:Tumor Suppressor Protein p53; D019098:Telomerase