title: The role of poly (adenosine 5'-diphosphate-ribose) polymerase in the response of pituitary tumor cells to reactive oxygen species.
abstract: As an enzyme implicated in the stress response, we investigated poly(ADP-ribose) polymerase (PARP) in the response of GH3 rat pituitary tumor cells to oxidants. These cells are unusual in that they undergo rapid cell death (90 min) with low doses of the prooxidant, H2O2 (50-200 microm), whereas at higher doses (1 mm), death occurs some hours later (4-5 h). Measurement of PARP activity shows that low doses of H2O2 (50-200 microm) fail to increase the activity of PARP, whereas at 0.5 and 1 mm, the enzyme becomes activated. In parallel with the activation of PARP, cellular ATP concentrations fall at high H2O2 doses and the PARP inhibitors, 3-aminobenzamide and nicotinamide (NIC) partially prevent this fall. Using NIC to inhibit PARP activity, we show that treatment of cells with NIC before the addition of H2O2 (0.5-1 mm), results in rapid cell death (90 min). In contrast, prior exposure to H2O2 (0.5-1 mm) for 1 h, before withdrawal and exposure to 1 mm NIC, allows cell survival for many hours. These data suggest that PARP is involved in blocking rapid death of GH3 cells in response to oxidants. In contrast to other cell types tested here, in which inhibitor studies show that PARP is activated at low H2O2 doses and this decreases the extent of apoptosis, GH3 cells are unable to sufficiently activate PARP to prevent rapid cell death.
authors.affiliation: Max-Planck-Institute of Psychiatry, Neuroendocrinology Group, Kraepelinstr. 10, D-80804 Munich, Germany.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Newton
authors.forename: Dennis
authors.initials: D
authors.lastname: Bilko
authors.forename: Maria
authors.initials: M
authors.lastname: Tichomirowa
authors.forename: Ulrich
authors.initials: U
authors.lastname: Renner
authors.forename: Günter K
authors.initials: GK
authors.lastname: Stalla
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D001549:Benzamides / Q000494:pharmacology; D016923:Cell Death; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008564:Membrane Potentials; D008928:Mitochondria / Q000473:pathology; D009536:Niacinamide / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D010911:Pituitary Neoplasms / Q000201:enzymology* / Q000473:pathology*; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D051381:Rats; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D001549:Benzamides; D016877:Oxidants; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D009536:Niacinamide; C025160:3-aminobenzamide; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D011065:Poly(ADP-ribose) Polymerases; C022616:thiazolyl blue; D005947:Glucose