Redox cycling of catechol estrogens generating apurinic/apyrimidinic sites and 8-oxo-deoxyguanosine via reactive oxygen species differentiates equine and human estrogens.
Abstract: Metabolic activation of estrogens to catechols and further oxidation to highly reactive o-quinones generates DNA damage including apurinic/apyrimidinic (AP) sites. 4-Hydroxyequilenin (4-OHEN) is the major catechol metabolite of equine estrogens present in estrogen replacement formulations, known to cause DNA strand breaks, oxidized bases, and stable and depurinating adducts. However, the direct formation of AP sites by 4-OHEN has not been characterized. In the present study, the induction of AP sites in vitro by 4-OHEN and the endogenous catechol estrogen metabolite, 4-hydroxyestrone (4-OHE), was examined by an aldehyde reactive probe assay. Both 4-OHEN and 4-OHE can significantly enhance the levels of AP sites in calf thymus DNA in the presence of the redox cycling agents, copper ion and NADPH. The B-ring unsaturated catechol 4-OHEN induced AP sites without added copper, whereas 4-OHE required copper. AP sites were also generated much more rapidly by 4-OHEN. For both catechol estrogens, the levels of AP sites correlated linearly with 8-oxo-dG levels, implying that depuriniation resulted from reactive oxygen species (ROS) rather than depurination of estrogen-DNA adducts. ROS modulators such as catalase, which scavenges hydrogen peroxide and a Cu(I) chelator, blocked the formation of AP sites. In MCF-7 breast cancer cells, 4-OHEN significantly enhanced the formation of AP sites with added NADH. In contrast, no significant induction of AP sites was detected in 4-OHE-treated cells. The greater redox activity of the equine catechol estrogen produces rapid oxidative DNA damage via ROS, which is enhanced by redox cycling agents and interestingly by NADPH-dependent quinone oxidoreductase.
Publication Date: 2010-06-01 PubMed ID: 20509668PubMed Central: PMC2922465DOI: 10.1021/tx1001282Google Scholar: Lookup
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Summary
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This study explores how the metabolic activation of estrogens into catechols and their further oxidation into o-quinones, such as 4-hydroxyequilenin (4-OHEN), can lead to DNA damage. The researchers discovered that both 4-OHEN and another common catechol estrogen metabolite, 4-hydroxyestrone (4-OHE), can increase levels of DNA damage in vitro when coupled with redox cycling agents. Notably, the research indicates that this DNA damage results from reactive oxygen species (ROS) rather than depurination of estrogen-DNA adducts.
Metabolic Activation of Estrogens
- The researchers investigated the metabolic activation of estrogens to catechols and their further oxidation to highly reactive o-quinones. These processes cause DNA damage, centering around apurinic/apyrimidinic (AP) sites.
- The primary catechol metabolite of equine estrogens, 4-hydroxyequilenin (4-OHEN), known to cause DNA strand breaks, oxidized bases, and stable and depurinating adducts was the focal point of this research.
Induction of DNA Damage in Vitro
- This study examined the in vitro generation of AP sites by 4-OHEN and 4-hydroxyestrone (4-OHE), another endogenous catechol estrogen metabolite, with the use of the aldehyde reactive probe assay.
- An interesting observation was that both 4-OHEN and 4-OHE can significantly enhance the levels of AP sites in calf thymus DNA in the presence of the redox cycling agents, a copper ion, and NADPH.
- Here, the 4-OHEN induced AP sites without the need for additional copper, unlike 4-OHE. Moreover, AP sites were generated more rapidly by 4-OHEN.
Role of Reactive Oxygen Species
- The research found that for both tested catechol estrogens, the levels of AP sites correlated linearly with 8-oxo-dG levels, indicating that the depurination resulted from reactive oxygen species (ROS) rather than depurination of estrogen-DNA adducts.
- The influence of ROS was further underpinned by the fact that the formation of AP sites was blocked by ROS modulators such as catalase, which scavenges hydrogen peroxide, and a Cu(I) chelator.
- In MCF-7 breast cancer cells, 4-OHEN considerably increased the formation of AP sites alongside added NADH. Comparatively, the treatment of cells with 4-OHE yielded no significant induction of AP sites.
The Significance of the Findings
- The implication of this research is the enlightening discovery of the redox cycling behavior of catechol estrogens, differentiating equine and human estrogens.
- Overall, the greater redox activity of the equine catechol estrogen results in rapid oxidative DNA damage via ROS, further potentiated by redox cycling agents and intriguingly by NADPH-dependent quinone oxidoreductase.
Cite This Article
APA
Wang Z, Chandrasena ER, Yuan Y, Peng KW, van Breemen RB, Thatcher GR, Bolton JL.
(2010).
Redox cycling of catechol estrogens generating apurinic/apyrimidinic sites and 8-oxo-deoxyguanosine via reactive oxygen species differentiates equine and human estrogens.
Chem Res Toxicol, 23(8), 1365-1373.
https://doi.org/10.1021/tx1001282 Publication
Researcher Affiliations
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612-7231, USA.
MeSH Terms
- 8-Hydroxy-2'-Deoxyguanosine
- Animals
- Cattle
- Cell Line, Tumor
- Chelating Agents / pharmacology
- Copper / chemistry
- Copper / metabolism
- DNA / metabolism
- DNA Damage
- DNA, Neoplasm / metabolism
- Deoxyguanosine / analogs & derivatives
- Deoxyguanosine / metabolism
- Equilenin / analogs & derivatives
- Equilenin / chemistry
- Equilenin / metabolism
- Estrogens, Catechol / chemistry
- Estrogens, Catechol / metabolism
- Estrogens, Catechol / pharmacology
- Free Radical Scavengers / pharmacology
- Horses
- Humans
- Hydrogen Peroxide / pharmacology
- Hydroxyestrones / chemistry
- Hydroxyestrones / metabolism
- Molecular Structure
- NADP / chemistry
- NADP / metabolism
- Oxidation-Reduction / drug effects
- Reactive Oxygen Species / metabolism
- Structure-Activity Relationship
Grant Funding
- R01 CA130037 / NCI NIH HHS
- R01 CA130037-05 / NCI NIH HHS
- CA130037 / NCI NIH HHS
References
This article includes 59 references
- Chen WY. Exogenous and endogenous hormones and breast cancer.. Best Pract Res Clin Endocrinol Metab 2008 Aug;22(4):573-85.
- Colditz GA, Hankinson SE, Hunter DJ, Willett WC, Manson JE, Stampfer MJ, Hennekens C, Rosner B, Speizer FE. The use of estrogens and progestins and the risk of breast cancer in postmenopausal women.. N Engl J Med 1995 Jun 15;332(24):1589-93.
- Key T, Appleby P, Barnes I, Reeves G. Endogenous sex hormones and breast cancer in postmenopausal women: reanalysis of nine prospective studies.. J Natl Cancer Inst 2002 Apr 17;94(8):606-16.
- Grodstein F, Stampfer MJ, Colditz GA, Willett WC, Manson JE, Joffe M, Rosner B, Fuchs C, Hankinson SE, Hunter DJ, Hennekens CH, Speizer FE. Postmenopausal hormone therapy and mortality.. N Engl J Med 1997 Jun 19;336(25):1769-75.
- Lupulescu A. Estrogen use and cancer incidence: a review.. Cancer Invest 1995;13(3):287-95.
- Service RF. New role for estrogen in cancer?. Science 1998 Mar 13;279(5357):1631-3.
- Vogel VG, Yeomans A, Higginbotham E. Clinical management of women at increased risk for breast cancer.. Breast Cancer Res Treat 1993 Nov;28(2):195-210.
- Zumoff B. Does postmenopausal estrogen administration increase the risk of breast cancer? Contributions of animal, biochemical, and clinical investigative studies to a resolution of the controversy.. Proc Soc Exp Biol Med 1998 Jan;217(1):30-7.
- Feigelson HS, Henderson BE. Estrogens and breast cancer.. Carcinogenesis 1996 Nov;17(11):2279-84.
- Henderson BE, Feigelson HS. Hormonal carcinogenesis.. Carcinogenesis 2000 Mar;21(3):427-33.
- Nandi S, Guzman RC, Yang J. Hormones and mammary carcinogenesis in mice, rats, and humans: a unifying hypothesis.. Proc Natl Acad Sci U S A 1995 Apr 25;92(9):3650-7.
- Flötotto T, Djahansouzi S, Gläser M, Hanstein B, Niederacher D, Brumm C, Beckmann MW. Hormones and hormone antagonists: mechanisms of action in carcinogenesis of endometrial and breast cancer.. Horm Metab Res 2001 Aug;33(8):451-7.
- Yager JD, Davidson NE. Estrogen carcinogenesis in breast cancer.. N Engl J Med 2006 Jan 19;354(3):270-82.
- Bolton JL, Thatcher GR. Potential mechanisms of estrogen quinone carcinogenesis.. Chem Res Toxicol 2008 Jan;21(1):93-101.
- Gaikwad NW, Yang L, Muti P, Meza JL, Pruthi S, Ingle JN, Rogan EG, Cavalieri EL. The molecular etiology of breast cancer: evidence from biomarkers of risk.. Int J Cancer 2008 May 1;122(9):1949-57.
- Li JJ, Li SA, Oberley TD, Parsons JA. Carcinogenic activities of various steroidal and nonsteroidal estrogens in the hamster kidney: relation to hormonal activity and cell proliferation.. Cancer Res 1995 Oct 1;55(19):4347-51.
- Cavalieri E, Chakravarti D, Guttenplan J, Hart E, Ingle J, Jankowiak R, Muti P, Rogan E, Russo J, Santen R, Sutter T. Catechol estrogen quinones as initiators of breast and other human cancers: implications for biomarkers of susceptibility and cancer prevention.. Biochim Biophys Acta 2006 Aug;1766(1):63-78.
- Bolton JL. Quinoids, quinoid radicals, and phenoxyl radicals formed from estrogens and antiestrogens.. Toxicology 2002 Aug 1;177(1):55-65.
- Cavalieri EL, Stack DE, Devanesan PD, Todorovic R, Dwivedy I, Higginbotham S, Johansson SL, Patil KD, Gross ML, Gooden JK, Ramanathan R, Cerny RL, Rogan EG. Molecular origin of cancer: catechol estrogen-3,4-quinones as endogenous tumor initiators.. Proc Natl Acad Sci U S A 1997 Sep 30;94(20):10937-42.
- Sarabia SF, Zhu BT, Kurosawa T, Tohma M, Liehr JG. Mechanism of cytochrome P450-catalyzed aromatic hydroxylation of estrogens.. Chem Res Toxicol 1997 Jul;10(7):767-71.
- Zhang F, Chen Y, Pisha E, Shen L, Xiong Y, van Breemen RB, Bolton JL. The major metabolite of equilin, 4-hydroxyequilin, autoxidizes to an o-quinone which isomerizes to the potent cytotoxin 4-hydroxyequilenin-o-quinone.. Chem Res Toxicol 1999 Feb;12(2):204-13.
- Spink DC, Zhang F, Hussain MM, Katz BH, Liu X, Hilker DR, Bolton JL. Metabolism of equilenin in MCF-7 and MDA-MB-231 human breast cancer cells.. Chem Res Toxicol 2001 May;14(5):572-81.
- Wang Z, Edirisinghe P, Sohn J, Qin Z, Geacintov NE, Thatcher GR, Bolton JL. Development of a liquid chromatography electrospray ionization tandem mass spectrometry method for analysis of stable 4-hydroxyequilenin-DNA adducts in human breast cancer cells.. Chem Res Toxicol 2009 Jun;22(6):1129-36.
- Yasui M, Matsui S, Laxmi YR, Suzuki N, Kim SY, Shibutani S, Matsuda T. Mutagenic events induced by 4-hydroxyequilin in supF shuttle vector plasmid propagated in human cells.. Carcinogenesis 2003 May;24(5):911-7.
- Chen Y, Liu X, Pisha E, Constantinou AI, Hua Y, Shen L, van Breemen RB, Elguindi EC, Blond SY, Zhang F, Bolton JL. A metabolite of equine estrogens, 4-hydroxyequilenin, induces DNA damage and apoptosis in breast cancer cell lines.. Chem Res Toxicol 2000 May;13(5):342-50.
- Pisha E, Lui X, Constantinou AI, Bolton JL. Evidence that a metabolite of equine estrogens, 4-hydroxyequilenin, induces cellular transformation in vitro.. Chem Res Toxicol 2001 Jan;14(1):82-90.
- Margalioth EJ, Schenker JG, Chevion M. Copper and zinc levels in normal and malignant tissues.. Cancer 1983 Sep 1;52(5):868-72.
- Prütz WA, Butler J, Land EJ. Interaction of copper(I) with nucleic acids.. Int J Radiat Biol 1990 Aug;58(2):215-34.
- Li Y, Trush MA, Yager JD. DNA damage caused by reactive oxygen species originating from a copper-dependent oxidation of the 2-hydroxy catechol of estradiol.. Carcinogenesis 1994 Jul;15(7):1421-7.
- Mobley JA, Bhat AS, Brueggemeier RW. Measurement of oxidative DNA damage by catechol estrogens and analogues in vitro.. Chem Res Toxicol 1999 Mar;12(3):270-7.
- Lin PH, Nakamura J, Yamaguchi S, Asakura S, Swenberg JA. Aldehydic DNA lesions induced by catechol estrogens in calf thymus DNA.. Carcinogenesis 2003 Jun;24(6):1133-41.
- Breen AP, Murphy JA. Reactions of oxyl radicals with DNA.. Free Radic Biol Med 1995 Jun;18(6):1033-77.
- Han X, Liehr JG. Microsome-mediated 8-hydroxylation of guanine bases of DNA by steroid estrogens: correlation of DNA damage by free radicals with metabolic activation to quinones.. Carcinogenesis 1995 Oct;16(10):2571-4.
- Chandrasena RE, Edirisinghe PD, Bolton JL, Thatcher GR. Problematic detoxification of estrogen quinones by NAD(P)H-dependent quinone oxidoreductase and glutathione-S-transferase.. Chem Res Toxicol 2008 Jul;21(7):1324-9.
- Wang Z, Wijewickrama GT, Peng KW, Dietz BM, Yuan L, van Breemen RB, Bolton JL, Thatcher GR. Estrogen Receptor {alpha} Enhances the Rate of Oxidative DNA Damage by Targeting an Equine Estrogen Catechol Metabolite to the Nucleus.. J Biol Chem 2009 Mar 27;284(13):8633-42.
- Ubezio P, Civoli F. Flow cytometric detection of hydrogen peroxide production induced by doxorubicin in cancer cells.. Free Radic Biol Med 1994 Apr;16(4):509-16.
- Thibodeau PA, Paquette B. DNA damage induced by catecholestrogens in the presence of copper (II): generation of reactive oxygen species and enhancement by NADH.. Free Radic Biol Med 1999 Dec;27(11-12):1367-77.
- Tan AS, Berridge MV. Differential effects of redox-cycling and arylating quinones on trans-plasma membrane electron transport.. Biofactors 2008;34(3):183-90.
- Lin PH, Pan WC, Kang YW, Chen YL, Lin CH, Lee MC, Chou YH, Nakamura J. Effects of naphthalene quinonoids on the induction of oxidative DNA damage and cytotoxicity in calf thymus DNA and in human cultured cells.. Chem Res Toxicol 2005 Aug;18(8):1262-70.
- Park JH, Gopishetty S, Szewczuk LM, Troxel AB, Harvey RG, Penning TM. Formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo) by PAH o-quinones: involvement of reactive oxygen species and copper(II)/copper(I) redox cycling.. Chem Res Toxicol 2005 Jun;18(6):1026-37.
- Li Y, Trush MA. DNA damage resulting from the oxidation of hydroquinone by copper: role for a Cu(II)/Cu(I) redox cycle and reactive oxygen generation.. Carcinogenesis 1993 Jul;14(7):1303-11.
- Son J, Pang B, McFaline JL, Taghizadeh K, Dedon PC. Surveying the damage: the challenges of developing nucleic acid biomarkers of inflammation.. Mol Biosyst 2008 Sep;4(9):902-8.
- Shen L, Pisha E, Huang Z, Pezzuto JM, Krol E, Alam Z, van Breemen RB, Bolton JL. Bioreductive activation of catechol estrogen-ortho-quinones: aromatization of the B ring in 4-hydroxyequilenin markedly alters quinoid formation and reactivity.. Carcinogenesis 1997 May;18(5):1093-101.
- Cavalieri EL, Rogan EG. Depurinating estrogen-DNA adducts in the etiology and prevention of breast and other human cancers.. Future Oncol 2010 Jan;6(1):75-91.
- Zhang Q, Aft RL, Gross ML. Estrogen carcinogenesis: specific identification of estrogen-modified nucleobase in breast tissue from women.. Chem Res Toxicol 2008 Aug;21(8):1509-13.
- Povirk LF, Steighner RJ. Oxidized apurinic/apyrimidinic sites formed in DNA by oxidative mutagens.. Mutat Res 1989 Sep;214(1):13-22.
- Lin CH, Leow HT, Huang SC, Nakamura J, Swenberg JA, Lin PH. Induction of cytotoxicity, aldehydic DNA lesions, and poly(ADP-ribose) polymerase-1 activation by catechol derivatives of pentachlorophenol in calf thymus DNA and in human breast cancer cells.. Chem Res Toxicol 2005 Feb;18(2):257-64.
- Spencer WA, Lehmler HJ, Robertson LW, Gupta RC. Oxidative DNA adducts after Cu(2+)-mediated activation of dihydroxy PCBs: role of reactive oxygen species.. Free Radic Biol Med 2009 May 15;46(10):1346-52.
- Yamamoto K, Kawanishi S. Hydroxyl free radical is not the main active species in site-specific DNA damage induced by copper (II) ion and hydrogen peroxide.. J Biol Chem 1989 Sep 15;264(26):15435-40.
- Gaikwad NW, Rogan EG, Cavalieri EL. Evidence from ESI-MS for NQO1-catalyzed reduction of estrogen ortho-quinones.. Free Radic Biol Med 2007 Nov 1;43(9):1289-98.
- Singh S, Zahid M, Saeed M, Gaikwad NW, Meza JL, Cavalieri EL, Rogan EG, Chakravarti D. NAD(P)H:quinone oxidoreductase 1 Arg139Trp and Pro187Ser polymorphisms imbalance estrogen metabolism towards DNA adduct formation in human mammary epithelial cells.. J Steroid Biochem Mol Biol 2009 Oct;117(1-3):56-66.
- Chen ZH, Na HK, Hurh YJ, Surh YJ. 4-Hydroxyestradiol induces oxidative stress and apoptosis in human mammary epithelial cells: possible protection by NF-kappaB and ERK/MAPK.. Toxicol Appl Pharmacol 2005 Oct 1;208(1):46-56.
- Liu X, Yao J, Pisha E, Yang Y, Hua Y, van Breemen RB, Bolton JL. Oxidative DNA damage induced by equine estrogen metabolites: role of estrogen receptor alpha.. Chem Res Toxicol 2002 Apr;15(4):512-9.
- Mobley JA, Brueggemeier RW. Increasing the DNA damage threshold in breast cancer cells.. Toxicol Appl Pharmacol 2002 May 1;180(3):219-26.
- Lavigne JA, Goodman JE, Fonong T, Odwin S, He P, Roberts DW, Yager JD. The effects of catechol-O-methyltransferase inhibition on estrogen metabolite and oxidative DNA damage levels in estradiol-treated MCF-7 cells.. Cancer Res 2001 Oct 15;61(20):7488-94.
- Felty Q, Xiong WC, Sun D, Sarkar S, Singh KP, Parkash J, Roy D. Estrogen-induced mitochondrial reactive oxygen species as signal-transducing messengers.. Biochemistry 2005 May 10;44(18):6900-9.
- Park SA, Na HK, Kim EH, Cha YN, Surh YJ. 4-hydroxyestradiol induces anchorage-independent growth of human mammary epithelial cells via activation of IkappaB kinase: potential role of reactive oxygen species.. Cancer Res 2009 Mar 15;69(6):2416-24.
- Zhang F, Swanson SM, van Breemen RB, Liu X, Yang Y, Gu C, Bolton JL. Equine estrogen metabolite 4-hydroxyequilenin induces DNA damage in the rat mammary tissues: formation of single-strand breaks, apurinic sites, stable adducts, and oxidized bases.. Chem Res Toxicol 2001 Dec;14(12):1654-9.
- Okamoto Y, Chou PH, Kim SY, Suzuki N, Laxmi YR, Okamoto K, Liu X, Matsuda T, Shibutani S. Oxidative DNA damage in XPC-knockout and its wild mice treated with equine estrogen.. Chem Res Toxicol 2008 May;21(5):1120-4.
Citations
This article has been cited 21 times.- Yin J, Gates KS, Wang Y. N-Methyl-N-nitrosourea Induced 3'-Glutathionylated DNA-Cleavage Products in Mammalian Cells.. Anal Chem 2022 Nov 15;94(45):15595-15603.
- McCoy MA, Spicer D, Wells N, Hoogewijs K, Fiedler M, Baud MGJ. Biophysical Survey of Small-Molecule β-Catenin Inhibitors: A Cautionary Tale.. J Med Chem 2022 May 26;65(10):7246-7261.
- Fernandez-Lazaro CI, Martínez-González MÁ, Aguilera-Buenosvinos I, Gea A, Ruiz-Canela M, Romanos-Nanclares A, Toledo E. Dietary Antioxidant Vitamins and Minerals and Breast Cancer Risk: Prospective Results from the SUN Cohort.. Antioxidants (Basel) 2021 Feb 24;10(3).
- Stojanovic A, Veselinovic M, Draginic N, Rankovic M, Andjic M, Bradic J, Bolevich S, Antovic A, Jakovljevic V. The Influence of Menopause and Inflammation on Redox Status and Bone Mineral Density in Patients with Rheumatoid Arthritis.. Oxid Med Cell Longev 2021;2021:9458587.
- Nair AR, Pillai AJ, Nair N. Cardiovascular Changes in Menopause.. Curr Cardiol Rev 2021;17(4):e230421187681.
- Lee I, Zhang G, Mesaros C, Penning TM. Estrogen receptor-dependent and independent roles of benzo[a]pyrene in Ishikawa cells.. J Endocrinol 2020 Nov;247(2):139-151.
- Wu HC, Brennan LA, Goldberg M, Chung WK, Wei Y, Santella RM, Terry MB. Influence of pubertal development on urinary oxidative stress biomarkers in adolescent girls in the New York LEGACY cohort.. Free Radic Res 2020 Jun;54(6):431-441.
- Majhi PD, Sharma A, Roberts AL, Daniele E, Majewski AR, Chuong LM, Black AL, Vandenberg LN, Schneider SS, Dunphy KA, Jerry DJ. Effects of Benzophenone-3 and Propylparaben on Estrogen Receptor-Dependent R-Loops and DNA Damage in Breast Epithelial Cells and Mice.. Environ Health Perspect 2020 Jan;128(1):17002.
- Bourgonje AR, Abdulle AE, Al-Rawas AM, Al-Maqbali M, Al-Saleh M, Enriquez MB, Al-Siyabi S, Al-Hashmi K, Al-Lawati I, Bulthuis MLC, Mulder DJ, Gordijn SJ, van Goor H, Saleh J. Systemic Oxidative Stress Is Increased in Postmenopausal Women and Independently Associates with Homocysteine Levels.. Int J Mol Sci 2020 Jan 2;21(1).
- Penning TM. Genotoxicity of ortho-quinones: reactive oxygen species versus covalent modification.. Toxicol Res (Camb) 2017;6(6):740-754.
- Yasuda MT, Sakakibara H, Shimoi K. Estrogen- and stress-induced DNA damage in breast cancer and chemoprevention with dietary flavonoid.. Genes Environ 2017;39:10.
- Bolton JL, Dunlap T. Formation and Biological Targets of Quinones: Cytotoxic versus Cytoprotective Effects.. Chem Res Toxicol 2017 Jan 17;30(1):13-37.
- Holmes S, Singh M, Su C, Cunningham RL. Effects of Oxidative Stress and Testosterone on Pro-Inflammatory Signaling in a Female Rat Dopaminergic Neuronal Cell Line.. Endocrinology 2016 Jul;157(7):2824-35.
- Amrita J, Mahajan M, Bhanwer AJ, Mohan G. Oxidative Stress: An Effective Prognostic Tool for an Early Detection of Cardiovascular Disease in Menopausal Women.. Biochem Res Int 2016;2016:6157605.
- Das Gupta S, Sae-tan S, Wahler J, So JY, Bak MJ, Cheng LC, Lee MJ, Lin Y, Shih WJ, Shull JD, Safe S, Yang CS, Suh N. Dietary γ-Tocopherol-Rich Mixture Inhibits Estrogen-Induced Mammary Tumorigenesis by Modulating Estrogen Metabolism, Antioxidant Response, and PPARγ.. Cancer Prev Res (Phila) 2015 Sep;8(9):807-16.
- Agacayak E, Basaranoglu S, Tunc SY, Icen MS, Findik FM, Kaplan I, Evliyaoglu O, Gul T. Oxidant/antioxidant status, paraoxonase activity, and lipid profile in plasma of ovariectomized rats under the influence of estrogen, estrogen combined with progesterone, and genistein.. Drug Des Devel Ther 2015;9:2975-82.
- Doshi SB, Agarwal A. The role of oxidative stress in menopause.. J Midlife Health 2013 Jul;4(3):140-6.
- Hemachandra LP, Patel H, Chandrasena RE, Choi J, Piyankarage SC, Wang S, Wang Y, Thayer EN, Scism RA, Michalsen BT, Xiong R, Siklos MI, Bolton JL, Thatcher GR. SERMs attenuate estrogen-induced malignant transformation of human mammary epithelial cells by upregulating detoxification of oxidative metabolites.. Cancer Prev Res (Phila) 2014 May;7(5):505-15.
- Christophersen OA. Should autism be considered a canary bird telling that Homo sapiens may be on its way to extinction?. Microb Ecol Health Dis 2012;23.
- Fleck SC, Hildebrand AA, Müller E, Pfeiffer E, Metzler M. Genotoxicity and inactivation of catechol metabolites of the mycotoxin zearalenone.. Mycotoxin Res 2012 Nov;28(4):267-73.
- Johnson KM, Price NE, Wang J, Fekry MI, Dutta S, Seiner DR, Wang Y, Gates KS. On the formation and properties of interstrand DNA-DNA cross-links forged by reaction of an abasic site with the opposing guanine residue of 5'-CAp sequences in duplex DNA.. J Am Chem Soc 2013 Jan 23;135(3):1015-25.
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