title: Effects of side-stream tobacco smoke and smoke extract on glutathione- and oxidative DNA damage repair-deficient mice and blood cells.
abstract: Cigarette smoke causes direct oxidative DNA damage as well as indirect damage through inflammation. Epidemiological studies show a strong relationship between secondhand smoke and cancer; however, the mechanisms of secondhand smoke-induced cancer are not well understood. Animal models with either (i) deficient oxidative DNA damage repair, or (ii) a decreased capacity to combat oxidative stress may help determine the pathways important in mitigating damage caused by smoke. In this study, we used mice lacking Ogg1 and Myh, both of which are involved in base excision repair by removing oxidatively damaged DNA bases. Gclm-deficient mice, which have decreased levels of glutathione (GSH), were used to look at the role of smoke-induced oxidative damage. Ex vivo experiments show significantly elevated levels of DNA single-strand breaks and chromosomal aberrations in peripheral blood lymphocytes from Ogg1(-/-)Myh(-/-) double knockout mice compared to wild type (WT) mice after 24h of exposure to cigarette smoke extract (CSE). The average γH2AX foci per cell was significantly elevated 3h after exposure to CSE in cells from Ogg1(-/-)Myh(-/-) double knockout mice compared to wildtype mice. In vivo we found that all mice had increased markers of DNA damage after exposure to side-stream tobacco smoke (SSTS). Ogg1(-/-)Myh(-/-) and Gclm(-/-) mice had altered levels of peripheral blood glutathione after SSTS exposure whereas wild type mice did not. This may be due to differential regulation of glutathione synthesis in the lung. We also found that Ogg1(-/-)Myh(-/-) mice had a decreased lifespan after oral gavage with benzo[a]pyrene compared to wildtype mice and sham-exposed Ogg1(-/-)Myh(-/-) mice. Our results are important in investigating the roles of oxidative stress and oxidative DNA damage repair in cigarette smoke-induced cancers and characterizing the role of genetic polymorphisms in smoke-related disease susceptibility.
authors.affiliation: David Geffen School of Medicine at UCLA, Department of Pathology, Los Angeles, CA, United States; David Geffen School of Medicine at UCLA, Department of Environmental Health, Los Angeles, CA, United States; Pfizer Inc., Experimental Medicine, South San Francisco, California 94080, United States.
authors.forename: Mitsuko L
authors.initials: ML
authors.lastname: Yamamoto
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Chapman
authors.forename: Robert H
authors.initials: RH
authors.lastname: Schiestl
mesh_terms: D000818:Animals; D001773:Blood Cells / Q000187:drug effects* / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects / Q000235:genetics; D045647:DNA Glycosylases / Q000235:genetics; D049914:DNA Repair-Deficiency Disorders / Q000097:blood / Q000235:genetics* / Q000473:pathology; D005260:Female; D005721:Glutamate-Cysteine Ligase / Q000235:genetics; D005978:Glutathione / Q000172:deficiency* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics*; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution; D045647:DNA Glycosylases; C485990:Ogg1 protein, mouse; C061738:mutY adenine glycosylase; C560749:GCLM protein, mouse; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione
keywords: CSE; DNA damage; DNA repair; DSBs; ETS; Glutathione; MN; Myh; OMM; Ogg1; Ogg1(−/−)Myh(−/−); SSTS; WT; cigarette smoke extract; double stranded breaks; environmental tobacco smoke; micro-nucleus; side stream tobacco smoke; wild type