Both 17 beta-estradiol-2,3-quinone (E-2-2,3-Q) and 17 beta-estradiol-3,4-quinone (E-2-3,4-Q) are reactive metabolites of estrogen. Elevation of E-2-3,4-Q to E-2-2,3-Q ratio is thought to be an important indicator of estrogen-induced carcinogenesis. Our current study compared the cumulative body burden of these estrogen quinones in serum samples taken from Taiwanese women with breast cancer (n = 152) vs healthy controls (n = 75) by using albumin (Alb) adducts as biomarkers. Results clearly demonstrated the presence of cysteinyl adducts of E-2-2,3-Q-4-S-Alb and E-2-3,4-Q-2-S-Alb in all study population at levels ranging from 61.7-1330 to 66.6-1590 pmol/g, respectively. Correlation coefficient between E-2-2,3-Q-4-S-Alb and E-2-3,4-Q-2-S-Alb was 0.610 for controls and 0.767 for breast cancer patients (p < 0.001). We also noticed that in premenopausal subjects with body mass index (BMI) less than 27, background levels of E-2-3,4-Q-2-S-Alb was inversely proportional to BMI with about 25% increase in E-2-3,4-Q-2-S-Alb per 5 kg/m(2) decrease in BMI (p < 0.001). In addition, we confirmed that mean levels of E-2-3,4-Q-2-S-Alb in breast cancer patients were similar to 5-fold greater than in those of controls (p < 0.001). Overall, this evidence suggests that disparity in estrogen disposition and the subsequent elevation of cumulative body burden of E-2-3,4-Q may play a role in the development of breast cancer. (c) 2013 Elsevier Ireland Ltd. All rights reserved.
