The dynamics of chromatin carcinogen interactions in the human cell.

Human lung epithelioid cells were treated with Benzo (a) pyrene diol epoxide (anti) in order to establish the binding and removal of covalent adducts in chromosomal components. Isolating two different classes of mononucleosomes, it was found that their DNA contained different concentrations of B(a)PDE-DNA adducts, while in both these mononucleosomal preparations only histones H2A and H3 contained detectable amounts of the carcinogen. Further analysis showed that in the intact human cell the carcinogen-DNA adduct distribution is constantly changing as a function of differential accessibility and repair. These results emphasize the dynamics of chromatin-carcinogen modifications.