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Metabolomic profiling unravels DNA adducts in human breast that are formed from peroxidase mediated activation of estrogens to quinone methides.

Gaikwad NW - PLoS ONE (2013)

Bottom Line: Surprisingly quinone methides were found to be stable with t1/2 of 20.8 and 4.5 min respectively.Incubation of estrogens with lactoperoxidase (LPO) and H2O2 resulted in formation of respective quinone methides (E1(E2)-QM).The error prone repair of the damaged DNA can result in mutation of critical genes and subsequently cancer.

View Article: PubMed Central - PubMed

Affiliation: Department of Nutrition and Department of Environmental Toxicology, University of California Davis, Davis, California, United States of America.

ABSTRACT
Currently there are three major hypotheses that have been proposed for estrogen induced carcinogenicity, however exact etiology remains unknown. Based on the chemical logic, studies were undertaken to investigate if estrogens could generate quinone methides in an oxidative environment which then could cause DNA damage in humans. In presence of MnO2 estrogens were oxidized to quinone methides. Surprisingly quinone methides were found to be stable with t1/2 of 20.8 and 4.5 min respectively. Incubation of estrogens with lactoperoxidase (LPO) and H2O2 resulted in formation of respective quinone methides (E1(E2)-QM). Subsequent addition of adenine to the assay mixture lead to trapping of E1(E2)-QM, resulting in formation of adenine adducts of estrogens, E1(E2)-9-N-Ade. Targeted ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) based metabolomic analysis of the breast tissue extracts showed the presence of adenine adducts of estrogens, E1(E2)-9-N-Ade, along with other estrogen related metabolites. Identity of E1(E2)-N-Ade in LPO assay extracts and breast tissue extracts were confirmed by comparing them to pure synthesized E1(E2)-9-N-Ade standards. From these results, it is evident that peroxidase enzymes or peroxidase-like activity in human breast tissue could oxidize estrogens to electrophilic and stable quinone methides in a single step that covalently bind to DNA to form adducts. The error prone repair of the damaged DNA can result in mutation of critical genes and subsequently cancer. This article reports evidence for hitherto unknown estrogen metabolic pathway in human breast, catalyzed by peroxidase, which could initiate cancer.

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Estrogens were oxidized by chemical means as described in Materials and method.UV spectra and plot presenting decay of estrone quinone methide (E1QM) (A) and estradiol quinone methide (E2QM) (B). Observed t 1/2 for E1QM and E2QM was 20.8 and 4.5 min respectively.
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pone-0065826-g002: Estrogens were oxidized by chemical means as described in Materials and method.UV spectra and plot presenting decay of estrone quinone methide (E1QM) (A) and estradiol quinone methide (E2QM) (B). Observed t 1/2 for E1QM and E2QM was 20.8 and 4.5 min respectively.

Mentions: The chemically synthesized E1QM and E2QM had UV absorbance at 330 and 323 nm (Fig. 2), whereas MS peak at M+1, 268.9 and 271.1 m/z (Fig. 3). Fragmentation patterns of peak at 268.9 and 271.1 m/z are presented in fig. 3. Surprisingly both E1QM and E2QM were found to be stable even at room temperature with t1/2 of 20.8 and 4.5 min’s respectively (Fig. 2). Once the presence of quinone methides in the reaction mixture was established, then their potential DNA adducts were synthesized in a one pot reaction. Both E1-9-N-Ade and E2-9-N-Ade adducts are reported here for the first time and were used to probe estrogen metabolic pathway in vitro and in humans.


Metabolomic profiling unravels DNA adducts in human breast that are formed from peroxidase mediated activation of estrogens to quinone methides.

Gaikwad NW - PLoS ONE (2013)

Estrogens were oxidized by chemical means as described in Materials and method.UV spectra and plot presenting decay of estrone quinone methide (E1QM) (A) and estradiol quinone methide (E2QM) (B). Observed t 1/2 for E1QM and E2QM was 20.8 and 4.5 min respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3675060&req=5

pone-0065826-g002: Estrogens were oxidized by chemical means as described in Materials and method.UV spectra and plot presenting decay of estrone quinone methide (E1QM) (A) and estradiol quinone methide (E2QM) (B). Observed t 1/2 for E1QM and E2QM was 20.8 and 4.5 min respectively.
Mentions: The chemically synthesized E1QM and E2QM had UV absorbance at 330 and 323 nm (Fig. 2), whereas MS peak at M+1, 268.9 and 271.1 m/z (Fig. 3). Fragmentation patterns of peak at 268.9 and 271.1 m/z are presented in fig. 3. Surprisingly both E1QM and E2QM were found to be stable even at room temperature with t1/2 of 20.8 and 4.5 min’s respectively (Fig. 2). Once the presence of quinone methides in the reaction mixture was established, then their potential DNA adducts were synthesized in a one pot reaction. Both E1-9-N-Ade and E2-9-N-Ade adducts are reported here for the first time and were used to probe estrogen metabolic pathway in vitro and in humans.

Bottom Line: Surprisingly quinone methides were found to be stable with t1/2 of 20.8 and 4.5 min respectively.Incubation of estrogens with lactoperoxidase (LPO) and H2O2 resulted in formation of respective quinone methides (E1(E2)-QM).The error prone repair of the damaged DNA can result in mutation of critical genes and subsequently cancer.

View Article: PubMed Central - PubMed

Affiliation: Department of Nutrition and Department of Environmental Toxicology, University of California Davis, Davis, California, United States of America.

ABSTRACT
Currently there are three major hypotheses that have been proposed for estrogen induced carcinogenicity, however exact etiology remains unknown. Based on the chemical logic, studies were undertaken to investigate if estrogens could generate quinone methides in an oxidative environment which then could cause DNA damage in humans. In presence of MnO2 estrogens were oxidized to quinone methides. Surprisingly quinone methides were found to be stable with t1/2 of 20.8 and 4.5 min respectively. Incubation of estrogens with lactoperoxidase (LPO) and H2O2 resulted in formation of respective quinone methides (E1(E2)-QM). Subsequent addition of adenine to the assay mixture lead to trapping of E1(E2)-QM, resulting in formation of adenine adducts of estrogens, E1(E2)-9-N-Ade. Targeted ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) based metabolomic analysis of the breast tissue extracts showed the presence of adenine adducts of estrogens, E1(E2)-9-N-Ade, along with other estrogen related metabolites. Identity of E1(E2)-N-Ade in LPO assay extracts and breast tissue extracts were confirmed by comparing them to pure synthesized E1(E2)-9-N-Ade standards. From these results, it is evident that peroxidase enzymes or peroxidase-like activity in human breast tissue could oxidize estrogens to electrophilic and stable quinone methides in a single step that covalently bind to DNA to form adducts. The error prone repair of the damaged DNA can result in mutation of critical genes and subsequently cancer. This article reports evidence for hitherto unknown estrogen metabolic pathway in human breast, catalyzed by peroxidase, which could initiate cancer.

Show MeSH
Related in: MedlinePlus