Indexed on: 14 Nov '97Published on: 14 Nov '97Published in: Toxicology and Applied Pharmacology
Breathing air exposes humans and other mammals to various toxic agents including oxidative contaminants associated with fine particles of less than 2.5 micron which may be deposited in the deep lung and have been implicated in the increased morbidity and mortality correlated with air pollution. Oxidative damage from inhaled particles may include damage to DNA, thereby adversely affecting the immunosurveillance provided by alveolar macrophages. Using the rat alveolar macrophage cell line NR8383, we demonstrated that cell proliferation was inhibited by exogenous hydrogen peroxide, an oxidant naturally produced in cellular respiration and phagocytosis. Mercaptosuccinate, a specific inhibitor of the antioxidant enzyme glutathione peroxidase, also inhibited cell growth. Genes known to be coordinatively regulated in response to growth arrest and DNA damage, GADD45 and GADD153, were induced compared to the housekeeping gene beta-ACTIN by equitoxic doses of hydrogen peroxide and mercaptosuccinate. Hydrogen peroxide treatment of cells in which glutathione peroxidase was inhibited by mercaptosuccinate resulted in even greater induction of both GADD genes. This approach using the NR8383 alveolar macrophage cell line provides a model for studying genotoxicity at the mechanistic level at which stress-responsive genes involved in growth arrest and DNA-damage response are modulated.