Estrogen-nucleic acid adducts: reaction of 3,4-estrone-o-quinone radical anion with deoxyribonucleosides.
Metabolic activation of estradiol leading to the formation of catechol estrogens is believed to be a prerequisite for its genotoxic effects. Previous studies have shown that 3,4-estronequinone (3,4-EQ) can redox-cycle and is capable of inducing exclusively single-strand DNA breaks in MCF-7 breast cancer cells [Nutter et al. (1991) J. Biol. Chem. 226, 16380-16386]. These studies, however, could not provide conclusive evidence about the mechanism of estrogen carcinogenesis. In order to explore this in more detail, we have shown previously that 3,4-EQ can react with adenine under electrochemical reductive conditions to yield an estrogen-nucleic acid adduct [Abul-Hajj et al. (1995) J. Am. Chem. Soc. 117, 6144-6145]. In this paper, we report the synthesis and identification of nine estrogen-nucleic acid adducts obtained from reaction of 3,4-EQ with deoxycytidine, deoxythymidine, deoxyadenosine, and deoxyguanosine. Purification of reaction mixtures using HPLC gave sufficient quantities of reaction products for identification using 1H-NMR and mass spectral determinations. Reaction of 3,4-EQ with dCyd, dThd, dAdo, and dGuo gave the following estrogen-nucleic acid adducts: N4-(4-hydroxyestron-1-yl)deoxycytidine, N4-(4-hydroxyestron-2-yl)deoxycytidine, N3-(4-hydroxyestron-1-yl)thymine, N3-(4-hydroxyestron-1-yl)deoxythymidine, N6-(4-hydroxyestron-1-yl)deoxyadenosine, 8-(4-hydroxyestron-1-yl)adenine, N2-(4-hydroxyestron-1-yl)deoxyguanosine, 8-(4-hydroxyestron-1-yl)guanine, and 8-(4-hydroxyestron-2-yl)guanine. Adduction through the NH2 group of dAdo, dGuo, and dCyd results in formation of chemically stable adducts. On the other hand, adduction at C-8 led to the formation of several depurination adducts identified as 4-OHE1-1-C8-Gua, 4-OHE1-2-C8-Gua, and 4-OHE1-1-C8-Ade.
Akanni
A
A
Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis 55455, USA.
Abul-Hajj
Y J
YJ
D000838:Anions; D002273:Carcinogens / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003839:Deoxyadenosines / Q000737:chemistry; D003841:Deoxycytidine / Q000737:chemistry; D003849:Deoxyguanosine / Q000737:chemistry; D003853:Deoxyribonucleosides / Q000138:chemical synthesis / Q000737:chemistry*; D004963:Estrenes / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D013936:Thymidine / Q000737:chemistry
D000838:Anions; D002273:Carcinogens; D003839:Deoxyadenosines; D003853:Deoxyribonucleosides; D004963:Estrenes; D005609:Free Radicals; D003841:Deoxycytidine; C044208:1,5(10)-estradiene-3,4,17-trione; D003849:Deoxyguanosine; D013936:Thymidine