| 16256111 |
Toyooka T, Ibuki Y: Co-exposure to benzo [a] pyrene and UVA induces phosphorylation of histone H2AX. FEBS Lett. 2005 Nov 21;579(28):6338-42. Epub 2005 Oct 21.
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. |
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