title: Ubiquitous presence of O6-methylguanine in human peripheral and cord blood DNA.
abstract: O6-Methylguanine (O6-meG) is a powerful premutagenic lesion that can arise from exposure to methylating agents. Although it has been reported to occur in human DNA, no systematic epidemiological analysis of its occurrence in populations suffering general environmental exposure is available. We report here results from a study of the presence of O6-meG in maternal and cord blood leukocyte DNA of women not knowingly exposed to methylating agents. Using a modification of an already existing method capable of detecting the lesion at levels as low as 16 nmol/molG, the adduct was detected in 31 of 36 maternal and 30 of 36 cord samples, at levels ranging up to 192 nmol/molG. Adduct levels in maternal blood DNA were significantly higher than those in cord blood DNA (P < 0.05), and there was a strong correlation between adduct levels in the two tissues (P < 0.001). In bivariate analysis, no significant association of adduct levels in either tissue and residence air pollution, active and passive smoking status, or eating habits was found. However, intake of fruits/vegetables and of vitamin supplements showed nonstatistically significant trends toward being associated with lower adduct levels in both maternal and cord blood DNA. The same trend was observed after multivariate analysis where all the above variables were controlled for. These findings indicate that premutagenic methylation DNA damage is commonplace in individuals not known to have suffered excessive exposure to environmental methylating agents or their precursors and are compatible with an endogenous origin of this damage, possibly associated with endogenous nitrosation processes.
authors.affiliation: Laboratory of Chemical Carcinogenesis, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, Athens, Greece.
authors.forename: P
authors.initials: P
authors.lastname: Georgiadis
authors.forename: E
authors.initials: E
authors.lastname: Samoli
authors.forename: S
authors.initials: S
authors.lastname: Kaila
authors.forename: K
authors.initials: K
authors.lastname: Katsouyanni
authors.forename: S A
authors.initials: SA
authors.lastname: Kyrtopoulos
mesh_terms: D000328:Adult; D004247:DNA / Q000032:analysis*; D018736:DNA Adducts / Q000235:genetics*; D004249:DNA Damage / Q000235:genetics*; D004781:Environmental Exposure; D005260:Female; D005312:Fetal Blood; D006147:Guanine / Q000031:analogs & derivatives* / Q000032:analysis; D006801:Humans; D007962:Leukocytes; D011247:Pregnancy
chemical_list: D018736:DNA Adducts; D006147:Guanine; D004247:DNA; C008449:O-(6)-methylguanine