TY - JOUR
T1 - N-acetylcysteine blocks formation of cancer-initiating estrogen-DNA adducts in cells
AU - Zahid, Muhammad
AU - Saeed, Muhammad
AU - Ali, Mohammed F.
AU - Rogan, Eleanor G.
AU - Cavalieri, Ercole L.
N1 - Funding Information:
The authors thank Dr. Fang Lu and Dr. Nilesh W. Gaikwad for their contribution to these experiments. This research was supported by Prevention, LLC. Core support at the Eppley Institute was supported by Grant CA P30 36727 from the National Cancer Institute.
PY - 2010/8
Y1 - 2010/8
N2 - Catechol estrogens, especially 4-hydroxylated metabolites of 17β-estradiol (E2), are responsible for estrogen-induced carcinogenesis. 4-Hydroxyestradiol (4-OHE2), a major metabolite of E2 formed preferentially by cytochrome P-450 1B1, is oxidized to E2-3,4-quinone, which can react with DNA to yield the depurinating adducts 4-OHE2-1-N3Ade and 4-OHE2-1-N7Gua. The apurinic sites generated by the loss of these depurinating adducts induce mutations that could lead to cancer initiation. In this study, we have evaluated the effects of N-acetylcysteine (NAcCys) on the metabolism of two cell lines, MCF-10F (a normal human breast epithelial cell line) and E6 (a normal mouse mammary epithelial cell line), treated with 4-OHE2 or its reactive metabolite, E2-3,4-quinone. Extensive HPLC with electrochemical detection and UPLC-MS/MS analyses of the cell media demonstrated that the presence of NAcCys very efficiently shifted the estrogen metabolism toward protective methoxylation and conjugation pathways in multiple ways, whereas formation of depurinating DNA adducts was inhibited. Protection by NAcCys seems to be similar in both cell lines, irrespective of their origin (human or mouse) or the presence of estrogen receptor-α. This finding suggests that NAcCys, a common dietary supplement, could be used as a potential chemopreventive agent to block the initial step in the genotoxicity caused by catechol estrogen quinones.
AB - Catechol estrogens, especially 4-hydroxylated metabolites of 17β-estradiol (E2), are responsible for estrogen-induced carcinogenesis. 4-Hydroxyestradiol (4-OHE2), a major metabolite of E2 formed preferentially by cytochrome P-450 1B1, is oxidized to E2-3,4-quinone, which can react with DNA to yield the depurinating adducts 4-OHE2-1-N3Ade and 4-OHE2-1-N7Gua. The apurinic sites generated by the loss of these depurinating adducts induce mutations that could lead to cancer initiation. In this study, we have evaluated the effects of N-acetylcysteine (NAcCys) on the metabolism of two cell lines, MCF-10F (a normal human breast epithelial cell line) and E6 (a normal mouse mammary epithelial cell line), treated with 4-OHE2 or its reactive metabolite, E2-3,4-quinone. Extensive HPLC with electrochemical detection and UPLC-MS/MS analyses of the cell media demonstrated that the presence of NAcCys very efficiently shifted the estrogen metabolism toward protective methoxylation and conjugation pathways in multiple ways, whereas formation of depurinating DNA adducts was inhibited. Protection by NAcCys seems to be similar in both cell lines, irrespective of their origin (human or mouse) or the presence of estrogen receptor-α. This finding suggests that NAcCys, a common dietary supplement, could be used as a potential chemopreventive agent to block the initial step in the genotoxicity caused by catechol estrogen quinones.
KW - Breast epithelial cells
KW - Cancer prevention
KW - Catechol estrogen quinones
KW - Depurinating estrogen-DNA adducts
KW - Free radicals
KW - Homeostasis of estrogen metabolism
KW - N-acetylcysteine
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U2 - 10.1016/j.freeradbiomed.2010.04.028
DO - 10.1016/j.freeradbiomed.2010.04.028
M3 - Article
C2 - 20472053
AN - SCOPUS:77954144592
VL - 49
SP - 392
EP - 400
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
SN - 0891-5849
IS - 3
ER -