NR8383 ALVEOLAR MACROPHAGE TOXIC GROWTH ARREST BY HYDROGEN-PEROXIDE IS ASSOCIATED WITH INDUCTION OF GROWTH-ARREST AND DNA DAMAGE-INDUCIBLE GENES GADD45 AND GADD153

Breathing air exposes humans and other mammals to various toxic agents including oxidative contaminants associated with fine particles of le ss than 2.5 mu m which may be deposited in the deep lung and have been implicated in the increased morbidity and mortality correlated with a ir pollution. Oxidative damage from inhaled particles may include dama ge 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 exoge nous hydrogen peroxide, an oxidant naturally produced in cellular resp iration and phagocytosis. Mercaptosuccinate, a specific inhibitor of t he antioxidant enzyme glutathione peroxidase, also inhibited cell grow th. Genes known to be coordinatively regulated in response to growth a rrest 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 g lutathione peroxidase was inhibited by mercaptosuccinate resulted in e ven greater induction of both GADD genes. This approach using the NR83 83 alveolar macrophage cell line provides a model for studying genotox icity at the mechanistic level at which stress-responsive genes involv ed in growth arrest and DNA-damage response are modulated. (C) 1997 Ac ademic Press.