title: Poly(ADP-ribose) polymerase-independent potentiation of nitrosourea cytotoxicity by 3-aminobenzamide in human malignant glioma cells.
abstract: Poly(ADP-ribose) polymerase is a zinc-finger DNA-binding protein that detects specifically DNA strand breaks generated by genotoxic agents and is thought to be involved in DNA repair. Here, we examined the effects of 3-aminobenzamide, a poly(ADP-ribose) polymerase inhibitor, on the chemosensitivity of human malignant glioma cells. 3-Aminobenzamide selectively potentiated the cytotoxicity of the nitrosoureas, nimustine, carmustine and lomustine in 10 of 12 human malignant glioma cell lines. In contrast, 3-aminobenzamide did not modulate the cytotoxic effects of doxorubicine, teniposide, vincristine, camptothecin or cytarabine. The nitrosoureas did not induce poly(ADP-ribose) polymerase activity in the glioma cells. Ectopic expression of truncated poly(ADP-ribose) polymerase containing the poly(ADP-ribose) polymerase DNA-binding domain, which acts as a dominant-negative mutant, in LN-18 or LN-229 cells did not alter the 3-aminobenzamide effect on nitrosourea-mediated cytotoxicity. Thus, 3-aminobenzamide may target another nicotinamide adenine dinucleotide (NAD)-requiring enzyme, but not poly(ADP-ribose) polymerase, when enhancing nitrosourea cytotoxicity in human malignant glioma cells. Carmustine cytotoxicity was associated with a G2/M arrest. Coexposure to carmustine and 3-aminobenzamide overcame this G2/M arrest in T98G cells, which are sensitized to carmustine by 3-aminobenzamide, but not in U251MG cells, which are refractory to 3-aminobenzamide-mediated sensitization to carmustine. Thus, 3-aminobenzamide-mediated sensitization to carmustine cytotoxicity may result from interference with the stable G2/M arrest response to carmustine in human glioma cells.
authors.affiliation: Laboratory of Molecular Neuro-Oncology, Department of Neurology, University of Tübingen, Medical School, Tübingen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Winter
authors.forename: M
authors.initials: M
authors.lastname: Weller
mesh_terms: D001549:Benzamides / Q000494:pharmacology*; D001665:Binding Sites; D002330:Carmustine / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D016195:G2 Phase / Q000187:drug effects; D005910:Glioma / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D008130:Lomustine / Q000494:pharmacology; D008770:Methylnitrosourea / Q000494:pharmacology; D008938:Mitosis / Q000187:drug effects; D015376:Nimustine / Q000494:pharmacology; D009607:Nitrosourea Compounds / Q000494:pharmacology*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D001549:Benzamides; D004791:Enzyme Inhibitors; D009607:Nitrosourea Compounds; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D015376:Nimustine; D008770:Methylnitrosourea; D008130:Lomustine; C025160:3-aminobenzamide; D011065:Poly(ADP-ribose) Polymerases; D002330:Carmustine