TY - JOUR
T1 - Estrogen metabolism and formation of estrogen-DNA adducts in estradiol-treated MCF-10F cells. The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin induction and catechol-O-methyltransferase inhibition
AU - Lu, Fang
AU - Zahid, Muhammad
AU - Saeed, Muhammad
AU - Cavalieri, Ercole L.
AU - Rogan, Eleanor G.
N1 - Funding Information:
F. Lu was supported by a fellowship from the University of Nebraska Environmental Toxicology Graduate Program. This study was supported by U.S.P.H.S. grant P01 CA49210 from the National Cancer Institute and Department of Defense grant DAMD17-03-1-0299 from the U.S. Army Breast Cancer Research Program. Core support at the Eppley Institute was provided by grant P30 CA36727 from the National Cancer Institute.
PY - 2007/6
Y1 - 2007/6
N2 - Formation of estrogen metabolites that react with DNA is thought to be a mechanism of cancer initiation by estrogens. The estrogens estrone (E1) and estradiol (E2) can form catechol estrogen (CE) metabolites, catechol estrogen quinones [E1(E2)-3,4-Q], which react with DNA to form predominantly depurinating adducts. This may lead to mutations that initiate cancer. Catechol-O-methyltransferase (COMT) catalyzes an inactivation (protective) pathway for CE. This study investigated the effect of inhibiting COMT activity on the levels of depurinating 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua adducts in human breast epithelial cells. MCF-10F cells were treated with TCDD, a cytochrome P450 inducer, then with E2 and Ro41-0960, a COMT inhibitor. Estrogen metabolites and depurinating DNA adducts in culture medium were analyzed by HPLC with electrochemical detection. Pre-treatment of cells with TCDD increased E2 metabolism to 4-OHE1(E2) and 4-OCH3E1(E2). Inclusion of Ro41-0960 and E2 in the medium blocked formation of methoxy CE, and depurinating adducts were observed. With Ro41-0960, more adducts were detected in MCF-10F cells exposed to 1 μM E2, whereas without the inhibitor, no increases in adducts were detected with E2 ≤ 10 μM. We conclude that low COMT activity and increased formation of depurinating adducts can be critical factors leading to initiation of breast cancer.
AB - Formation of estrogen metabolites that react with DNA is thought to be a mechanism of cancer initiation by estrogens. The estrogens estrone (E1) and estradiol (E2) can form catechol estrogen (CE) metabolites, catechol estrogen quinones [E1(E2)-3,4-Q], which react with DNA to form predominantly depurinating adducts. This may lead to mutations that initiate cancer. Catechol-O-methyltransferase (COMT) catalyzes an inactivation (protective) pathway for CE. This study investigated the effect of inhibiting COMT activity on the levels of depurinating 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua adducts in human breast epithelial cells. MCF-10F cells were treated with TCDD, a cytochrome P450 inducer, then with E2 and Ro41-0960, a COMT inhibitor. Estrogen metabolites and depurinating DNA adducts in culture medium were analyzed by HPLC with electrochemical detection. Pre-treatment of cells with TCDD increased E2 metabolism to 4-OHE1(E2) and 4-OCH3E1(E2). Inclusion of Ro41-0960 and E2 in the medium blocked formation of methoxy CE, and depurinating adducts were observed. With Ro41-0960, more adducts were detected in MCF-10F cells exposed to 1 μM E2, whereas without the inhibitor, no increases in adducts were detected with E2 ≤ 10 μM. We conclude that low COMT activity and increased formation of depurinating adducts can be critical factors leading to initiation of breast cancer.
KW - 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)
KW - Catechol-O-methyltransferase
KW - Depurinating estrogen-DNA adducts
KW - Estrogen metabolism
KW - MCF-10F cells
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U2 - 10.1016/j.jsbmb.2006.12.102
DO - 10.1016/j.jsbmb.2006.12.102
M3 - Article
C2 - 17582757
AN - SCOPUS:34547697291
SN - 0960-0760
VL - 105
SP - 150
EP - 158
JO - Journal of Steroid Biochemistry and Molecular Biology
JF - Journal of Steroid Biochemistry and Molecular Biology
IS - 1-5
ER -