title: Alternative NHEJ Pathway Components Are Therapeutic Targets in High-Risk Neuroblastoma.
abstract: In neuroblastoma, MYCN genomic amplification and segmental chromosomal alterations including 1p or 11q loss of heterozygocity and/or 17q gain are associated with progression and poor clinical outcome. Segmental alterations are the strongest predictor of relapse and result from unbalanced translocations attributable to erroneous repair of chromosomal breaks. Although sequence analysis of affected genomic regions suggests that these errors arise by nonhomologous end-joining (NHEJ) of DNA double-strand breaks (DSB), abnormalities in NHEJ have not been implicated in neuroblastoma pathogenesis. On this basis, the hypothesis that an error-prone mechanism of NHEJ is critical for neuroblastoma cell survival was tested. Plasmid-based DSB repair assays demonstrated efficient NHEJ activity in human neuroblastoma cells with repair products that were error-prone relative to nontransformed cells. Neuroblastoma cells derived from tumorigenic neuroblastic phenotypes had differential DNA repair protein expression patterns compared with nontumorigenic cells. Tumorigenic neuroblastoma cells were deficient in DNA ligase IV (Lig4) and Artemis (DCLRE1C), mediators of canonical NHEJ. Conversely, enzymes required for an error-prone alternative NHEJ pathway (alt-NHEJ), DNA Ligase IIIα (Lig3), DNA Ligase I (Lig1), and PARP1 protein were upregulated. Inhibition of Lig3 and Lig1 led to DSB accumulation and cell death, linking alt-NHEJ to cell survival in neuroblastoma. Neuroblastoma cells demonstrated sensitivity to PARP1 inhibition (PARPi) that paralleled PARP1 expression. In a dataset of human neuroblastoma patient tumors, overexpression of genes encoding alt-NHEJ proteins associated with poor survival.
  
  
  CONCLUSIONS
  These findings provide an insight into DNA repair fidelity in neuroblastoma and identify components of the alt-NHEJ pathway as promising therapeutic targets.
authors.affiliation: Department of Surgery, C.S. Mott Children and Women's Hospital, Translational Oncology Program, The University of Michigan Medical School, Ann Arbor, Michigan. eanewman@med.umich.edu.
authors.forename: Erika A
authors.initials: EA
authors.lastname: Newman
authors.affiliation: Department of Surgery, C.S. Mott Children and Women's Hospital, Translational Oncology Program, The University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Fujia
authors.initials: F
authors.lastname: Lu
authors.affiliation: Department of Surgery, C.S. Mott Children and Women's Hospital, Translational Oncology Program, The University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Daniela
authors.initials: D
authors.lastname: Bashllari
authors.affiliation: Department of Pediatrics, C.S. Mott Children and Women's Hospital, Translational Oncology Program, The University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Obstetrics and Gynecology, C.S. Mott Children and Women's Hospital, The University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Opipari
authors.affiliation: Department of Pediatrics, C.S. Mott Children and Women's Hospital, Translational Oncology Program, The University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Valerie P
authors.initials: VP
authors.lastname: Castle
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D059766:DNA End-Joining Repair / Q000187:drug effects; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009447:Neuroblastoma / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011379:Prognosis
chemical_list: D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D045643:DNA Repair Enzymes