title: Rapid Diminution in the Level and Activity of DNA-Dependent Protein Kinase in Cancer Cells by a Reactive Nitro-Benzoxadiazole Compound.
abstract: The expression and activity of DNA-dependent protein kinase (DNA-PK) is related to DNA repair status in the response of cells to exogenous and endogenous factors. Recent studies indicate that Epidermal Growth Factor Receptor (EGFR) is involved in modulating DNA-PK. It has been shown that a compound 4-nitro-7-[(1-oxidopyridin-2-yl)sulfanyl]-2,1,3-benzoxadiazole (NSC), bearing a nitro-benzoxadiazole (NBD) scaffold, enhances tyrosine phosphorylation of EGFR and triggers downstream signaling pathways. Here, we studied the behavior of DNA-PK and other DNA repair proteins in prostate cancer cells exposed to compound NSC. We showed that both the expression and activity of DNA-PKcs (catalytic subunit of DNA-PK) rapidly decreased upon exposure of cells to the compound. The decline in DNA-PKcs was associated with enhanced protein ubiquitination, indicating the activation of cellular proteasome. However, pretreatment of cells with thioglycerol abolished the action of compound NSC and restored the level of DNA-PKcs. Moreover, the decreased level of DNA-PKcs was associated with the production of intracellular hydrogen peroxide by stable dimeric forms of Cu/Zn SOD1 induced by NSC. Our findings indicate that reactive oxygen species and electrophilic intermediates, generated and accumulated during the redox transformation of NBD compounds, are primarily responsible for the rapid modulation of DNA-PKcs functions in cancer cells.
authors.affiliation: UFIP CNRS UMR 6286, Mechanism and Regulation of DNA Repair Team, Faculté des Sciences et des Techniques, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes, France. vivianeaos@gmail.com.
authors.forename: Viviane A O
authors.initials: VA
authors.lastname: Silva
authors.affiliation: UFIP CNRS UMR 6286, Mechanism and Regulation of DNA Repair Team, Faculté des Sciences et des Techniques, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes, France. florian.lafont@etu.univ-nantes.fr.
authors.forename: Florian
authors.initials: F
authors.lastname: Lafont
authors.affiliation: UFIP CNRS UMR 6286, Mechanism and Regulation of DNA Repair Team, Faculté des Sciences et des Techniques, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes, France. houda.benhelli@univ-nantes.fr.
authors.forename: Houda
authors.initials: H
authors.lastname: Benhelli-Mokrani
authors.affiliation: UFIP CNRS UMR 6286, Mechanism and Regulation of DNA Repair Team, Faculté des Sciences et des Techniques, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes, France. magali.lebreton@univ-nantes.fr.
authors.forename: Magali Le
authors.initials: ML
authors.lastname: Breton
authors.affiliation: Plate-forme MicroPICell SFR Santé F. Bonamy-FED 4203/Inserm UMS016/CNRS UMS3556, 44007 Nantes, France. philippe.hulin@univ-nantes.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Hulin
authors.affiliation: UFIP CNRS UMR 6286, Mechanism and Regulation of DNA Repair Team, Faculté des Sciences et des Techniques, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes, France. thomas.chabot1@etu.univ-nantes.fr.
authors.forename: Thomas
authors.initials: T
authors.lastname: Chabot
authors.affiliation: UMR 892 Inserm-6299 CNRS, team 14, 44007 Nantes, France. francois.paris@inserm.fr.
authors.forename: François
authors.initials: F
authors.lastname: Paris
authors.affiliation: IICiMed EA-1155, Faculté de Pharmacie, Faculté des Sciences et des Techniques, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes, France. vehary.sakanyan@univ-nantes.fr.|ProtNeteomix, 29 rue de Provence, 44700 Orvault, France. vehary.sakanyan@univ-nantes.fr.
authors.forename: Vehary
authors.initials: V
authors.lastname: Sakanyan
authors.affiliation: UFIP CNRS UMR 6286, Mechanism and Regulation of DNA Repair Team, Faculté des Sciences et des Techniques, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes, France. fabrice.fleury@univ-nantes.fr.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Fleury
mesh_terms: D045744:Cell Line, Tumor; D004260:DNA Repair / Q000187:drug effects; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects*; D005990:Glycerol / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008297:Male; D010069:Oxadiazoles / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D054875:Ubiquitination
chemical_list: C542965:7-nitrobenzoxadiazole; D010069:Oxadiazoles; C009465:thioglycerol; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D051747:DNA-Activated Protein Kinase; D005990:Glycerol
keywords: DNA repair; DNA-PKcs; SOD1; chemiosensitization; hydrogen peroxide; nitro-benzoxadiazole; prostate cancer; protein targeting