Cigarette
smoke contains a variety of
carcinogens, cocarcinogens,
mutagens, and
tumor promoters. In addition to polycyclic aromatic
carcinogens and tobacco-specific
nitrosamines, cigarette
smoke also contains an abundance of
catechols,
aldehydes, and other constituents, which are
DNA damaging directly or indirectly; therefore, they can also contribute to cigarette
smoke-mediated carcinogenicity. In this study, we investigated the potential of cigarette
smoke constituents to induce oxidative damage to
DNA through their capacity to redox cycle. When
DNA (300 μg/mL) was incubated with cigarette
smoke condensate (0.2 mg of tobacco
particulate matter/mL) and CuCl(2) as a catalyst (50-100 μM), a variety of oxidative
DNA adducts were detected by (32)P-postlabeling/TLC. Of the total adduct burden (2114 ± 419 adducts/10(6)
nucleotides), over 40% of all adducts were attributed to the benchmark oxidative DNA lesion, 8-oxodeoxyguanosine (8-oxodG). Adducts were formed dose dependently. Essentially, similar adduct profiles were obtained when cigarette
smoke condensate was substituted with ortho- and
para-dihydroxybenzenes. Vehicle treatment with Cu(2+) or CSC alone did not induce any significant amount of oxidative DNA damage. Furthermore, coincubation of cigarette
smoke condensate and ortho-dihydroxybenzene with
DNA resulted in a higher amount of oxidative
DNA adducts than obtained with the individual entity, suggesting that adducts presumably originated from
catechols or
catechol-like compounds in cigarette
smoke condensate. Adducts resulting from both cigarette
smoke condensate and pure dihydroxybenzenes were chromatographically identical to adducts formed by reaction of
DNA with H(2)O(2), which is known to produce
8-oxodG, and many other oxidative
DNA adducts. When the cigarette
smoke condensate-
DNA reaction was performed in the presence of
ellagic acid, a known
antioxidant, the adduct formation was inhibited dose dependently, further suggesting that adducts originated from oxidative pathway. Our data thus provide evidence of the capacity of
catechols or
catechol-like constituents in cigarette
smoke to produce oxidative DNA damage, which may contribute to the
tumor-promoting activity of cigarette
smoke.