Formation of an oxidative DNA damage, 8-hydroxydeoxyguanosine, in mouse lung DNA after intratracheal instillation of diesel exhaust particles and effects of high dietary fat and beta-carotene on this process

Abstract

Diesel exhaust particles (DEP) cause tumors in the respiratory tracts of experimental animals. It was previously shown that DEP produced superoxide and hydroxyl radical. To examine whether oxygen radicals are involved in mouse lung tumorigenesis induced by DEP, formation of an oxidative DNA damage, 8-hydroxydeoxyguanosine (oh8dG), by DEP was investigated. Furthermore, the role of high dietary fat and beta-carotene on this process was studied. After intratracheal instillation of DEP, a significant increase of oh8dG in mouse lung DNA was observed. High dietary fat enhanced the formation of oh8dG in lung DNA. Intake of beta-carotene suppressed the formation of oh8dG in lung DNA, but the protective effect of beta-carotene against this process was not statistically significant. These results suggest that formation of oh8dG in lung DNA was induced by oxygen free radicals produced by DEP. Thus, it is possible that oh8dG is a promutagenic lesion in DEP-induced lung tumorigenesis in mice and high dietary fat enhances this process through the generation of oh8dG in mouse lung DNA.