Cigarette Smoke and Asbestos Activate Poly-ADP-Ribose Polymerase in Alveolar Epithelial Cells

• Published in: Journal of investigative medicine Vol. 49; no. 1; pp. 68 - 76
• Main Authors: Kamp, David W., Srinivasan, Malathi, Weitzman, Sigmund A.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.01.2001; Sage Publications Ltd; SLACK INCORPORATED
• Subjects: Antioxidants - pharmacology; Asbestos, Amosite - toxicity; Carcinoma, Bronchogenic - etiology; Cell Line; Enzyme Activation - drug effects; Epithelial Cells - drug effects; Epithelial Cells - enzymology; Humans; Hydrogen Peroxide - toxicity; Poly(ADP-ribose) Polymerases - metabolism; Pulmonary Alveoli - drug effects; Pulmonary Alveoli - enzymology; Smoking - adverse effects; Smoking - metabolism; alveolar epithelial cells; asbestos; lung injury; DNA damage; reactive oxygen species; cigarette smoke; DNA repair
• ISSN: 1081-5589; 1708-8267
• DOI: 10.2310/6650.2001.34092

AbstractBackgroundCigarette smoke augments asbestos-induced bronchogenic carcinoma in a synergistic manner by mechanisms that are not established. One important mechanism may involve alveolar epithelial cell (AEC) injury resulting from oxidant-induced DNA damage that subsequently activates poly (ADP-ribose) polymerase (PARP), an enzyme involved in DNA repair that can deplete cellular energy stores. We previously showed that whole aqueous cigarette smoke extracts (CSE) augment amosite asbestos-induced DNA damage and cytotoxicity to cultured AEC in part by generating iron-induced free radicals. We hypothesized that CSE increase asbestos-induced AEC injury by triggering PARP activation resulting from DNA damage caused by iron-induced free radicals.MethodsAqueous CSE were prepared fresh on the day of each experiment. PARP activity in WI-26 (a type I-like cell line) and A549 (a type II-like cell line) cells was assessed by the uptake of labeled NAD over 4 hours and confirmed on the basis of the reduction of PARP levels in the presence of a PARP inhibitor, 3-aminobenzamide (3-ABA). Cell survival was assessed by trypan blue dye exclusion.ResultsHydrogen peroxide (H2O2; 1-250 μM), CSE (0.4-10 vol%), and amosite asbestos (5-250 μg/cm2) each caused PARP activation in WI-26 and A549 cells. The combination of asbestos (5 μg/cm2) and CSE (0.04-10%) induced WI-26 and A549 cell PARP activation without evidence of synergism. 3-ABA significantly attenuated WI-26 and A549 cell PARP activity and cell death after exposure to H2O2, CSE, and asbestos. Phytic acid, an iron chelator, catalase, and superoxide dismutase each decreased WI-26 cell PARP activation caused by asbestos and CSE.ConclusionsCSE and asbestos induce PARP activation in cultured AEC in a nonsynergistic manner. These data provide further support that asbestos and cigarette smoke are genotoxic to relevant lung target cells and that iron-induced free radicals in part cause these effects.