title: Co-exposure to benzo[a]pyrene and UVA induces phosphorylation of histone H2AX.
abstract: Phosphorylation of histone H2AX (termed gamma-H2AX) was recently identified as an early event after induction of DNA double strand breaks (DSBs). We have previously shown that co-exposure to benzo[a]pyrene (BaP), a wide-spread environmental carcinogen, and ultraviolet A (UVA), a major component of solar UV radiation, induced DSBs in mammalian cells. In the present study, we examined whether co-exposure to BaP and UVA generates gamma-H2AX in CHO-K1 cells. Single treatment with BaP (10(-9)-10(-7)M) or UVA ( approximately 2.4 J/cm(2)) did not result in gamma-H2AX, however, co-exposure drastically induced foci of gamma-H2AX in a dose-dependent manner. gamma-H2AX could be detected even at very low concentration of BaP (10(-9)M) plus UVA (0.6J/cm(2)), which did not change cell survival rates. NaN(3) effectively inhibited the formation of gamma-H2AX induced by co-exposure, indicating the contribution of singlet oxygen. This is the first evidence that co-exposure to BaP and UVA induced DSBs, involving gamma-H2AX.
authors.affiliation: Laboratory of Radiation Biology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1, Yada, Shizuoka-shi 422-8526, Japan.
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Toyooka
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ibuki
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D016166:Free Radical Scavengers / Q000494:pharmacology; D006657:Histones / Q000378:metabolism*; D010766:Phosphorylation; D026082:Singlet Oxygen / Q000378:metabolism; D019810:Sodium Azide / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D016166:Free Radical Scavengers; D006657:Histones; D026082:Singlet Oxygen; D001564:Benzo(a)pyrene; D019810:Sodium Azide