Overview of estrogen metabolism-induced DNA adduct formation and subsequent DNA repair by BER. The top sequence of reactions shows the CYP1B1-mediated oxidative estrogen metabolism resulting in estrogen-deoxyribonucleoside adduct formation. The bottom sequence of reactions shows the BER pathway with its two branches, the predominant short-patch pathway (left) and the alternate long-patch pathway (right). Not shown is the formation of the catechol estrogen 2-OH, which yields stable adducts, and the redox cycling of catechol estrogens and estrogen quinones, which generates reactive oxygen species capable of producing oxidative DNA adducts.
