title: Co-targeting deoxyribonucleic acid-dependent protein kinase and poly(adenosine diphosphate-ribose) polymerase-1 promotes accelerated senescence of irradiated cancer cells.
abstract: OBJECTIVE
  To examine the effects of combined blockade of DNA-dependent protein kinase (DNA-PK) and poly(adenosine diphosphate-ribose) polymerase-1 (PARP-1) on accelerated senescence in irradiated H460 and A549 non-small cell lung cancer cells.
  
  
  METHODS
  The effects of KU5788 and AG014699 (inhibitors of DNA-PK and PARP-1, respectively) on clonogenic survival, DNA double-strand breaks (DSBs), apoptosis, mitotic catastrophe, and accelerated senescence in irradiated cells were examined in vitro. For in vivo experiments, H460 xenografts established in athymic nude mice were treated with BEZ235 (a DNA-PK, ATM, and phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor) and AG014699 to determine effects on proliferation, DNA DSBs, and accelerated senescence after radiation.
  
  
  RESULTS
  Compared with either inhibitor alone, combination treatment with KU57788 and AG014699 reduced postradiation clonogenic survival and significantly increased persistence of Gamma-H2AX (γH2AX) foci in irradiated H460 and A549 cells. Notably, these effects coincided with the induction of accelerated senescence in irradiated cells as reflected by positive β-galactosidase staining, G2-M cell-cycle arrest, enlarged and flattened cellular morphology, increased p21 expression, and senescence-associated cytokine secretion. In irradiated H460 xenografts, concurrent therapy with BEZ235 and AG014699 resulted in sustained Gamma-H2AX (γH2AX) staining and prominent β-galactosidase activity.
  
  
  CONCLUSIONS
  Combined DNA-PK and PARP-1 blockade increased tumor cell radiosensitivity and enhanced the prosenescent properties of ionizing radiation in vitro and in vivo. These data provide a rationale for further preclinical and clinical testing of this therapeutic combination.
authors.affiliation: Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Pathology, St. Vincent's Hospital, University of Melbourne, Parkville, Victoria, Australia. Electronic address: arun.azad@bccancer.bc.ca.
authors.forename: Arun
authors.initials: A
authors.lastname: Azad
authors.affiliation: Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
authors.forename: Patricia
authors.initials: P
authors.lastname: Bukczynska
authors.affiliation: Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.
authors.forename: Susan
authors.initials: S
authors.lastname: Jackson
authors.affiliation: Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Ygal
authors.initials: Y
authors.lastname: Haupt
authors.affiliation: Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Ygal
authors.initials: Y
authors.lastname: Haput
authors.affiliation: Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Carleen
authors.initials: C
authors.lastname: Cullinane
authors.affiliation: Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Division of Cancer Medicine, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Parkville, Victoria, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Grant A
authors.initials: GA
authors.lastname: McArthur
authors.affiliation: Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Division of Cancer Medicine, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Parkville, Victoria, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Solomon
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D016922:Cellular Senescence; D002867:Chromones / Q000494:pharmacology*; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D004260:DNA Repair / Q000187:drug effects; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors*; D016195:G2 Phase / Q000187:drug effects; D006657:Histones / Q000032:analysis; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology*; D019394:Ki-67 Antigen / Q000032:analysis; D051379:Mice; D008819:Mice, Nude; D009025:Morpholines / Q000494:pharmacology*; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011804:Quinolines / Q000494:pharmacology; D011836:Radiation Tolerance / Q000187:drug effects* / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000032:analysis; D001616:beta-Galactosidase / Q000032:analysis
chemical_list: C499693:8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one; D002867:Chromones; D006657:Histones; D007093:Imidazoles; D007211:Indoles; D019394:Ki-67 Antigen; D009025:Morpholines; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D047428:Protein Kinase Inhibitors; D011804:Quinolines; D016159:Tumor Suppressor Protein p53; C475961:gamma-H2AX protein, mouse; C531549:rucaparib; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D051747:DNA-Activated Protein Kinase; D001616:beta-Galactosidase; C531198:dactolisib