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Lin C, Chen DR, Kuo SJ, Feng CY, Chen DR, Hsieh WC, Lin PH. Profiling of Protein Adducts of Estrogen Quinones in 5-Year Survivors of Breast Cancer Without Recurrence. Cancer Control 2022; 29:10732748221084196. [PMID: 35303784 PMCID: PMC8935573 DOI: 10.1177/10732748221084196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aims The aim of this study was to simultaneously analyze estrogen quinone-derived adducts, including 17β-estradiol-2,3-quinone (E2-2,3-Q) and 17β-estradiol-3,4-quinone (E2-3,4-Q), in human albumin (Alb) and hemoglobin (Hb) derived from breast cancer patients with five-year postoperative treatment without recurrence in Taiwan and to evaluate the treatment-related effects on the production of these adducts. Settings and Design Cohort Methods and Material: Blood samples derived from breast cancer 5-year survivors without recurrence were collected. Albumin and hemoglobin adducts of E2-3,4-Q and E2-2,3-Q were analyzed to evaluate the degree of disposition of estrogen to quinones and to compare these adduct levels with those in patients before treatment. Statistical Analysis All data are expressed as mean ± standard deviation of three determinations. We used Student’s t-test to examine subgroups. Data were transformed to the natural logarithm and tested for normal distribution for parametric analyses. Linear correlations were investigated between individual adduct levels by simple regression. Statistical analysis was performed using the SPSS Statistics 20.0. Results Result confirmed that logged levels of E2-2,3-Q-derived adducts correlated significantly with those of E2-3,4-Q-derived adducts (correlation coefficient r=.336-.624). Mean levels of E2-2,3-Q-4-S-Alb and E2-3,4-Q-2-S-Alb in 5-year survivors were reduced by 60-70% when compared to those in the breast cancer patients with less than one year of diagnosis/preoperative treatment (P<.001). Conclusions Our findings add support to the theme that hormonal therapy including aromatase inhibitors and Tamoxifen may dramatically reduce burden of estrogen quinones. We hypothesize that combination of treatment-related effects and environmental factors may modulate estrogen homeostasis and diminish the production of estrogen quinones in breast cancer patients.
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Affiliation(s)
- Che Lin
- Comprehensive Breast Cancer Center, 36596Changhua Christian Hospital, Changhua, Taiwan.,Department of Optometry, 89578Chung Hwa University of Medical Technology, Tainan, Taiwan
| | - Ding-Ru Chen
- Comprehensive Breast Cancer Center, 36596Changhua Christian Hospital, Changhua, Taiwan
| | - Shou-Jen Kuo
- Comprehensive Breast Cancer Center, 36596Changhua Christian Hospital, Changhua, Taiwan
| | - Chi-Yen Feng
- Department of Surgery, 89578Da-Chien Health Medical System, Taiwan
| | - Dar-Ren Chen
- Comprehensive Breast Cancer Center, 36596Changhua Christian Hospital, Changhua, Taiwan
| | - Wei-Chung Hsieh
- Department of Laboratory Medicine, 384207Da-Chien General Hospital, Miaoli, Taiwan
| | - Po-Hsiung Lin
- Department of Environmental Engineering, 34916National Chung Hsing University, Taichung, Taiwan
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Abstract
Chemicals are measured regularly in air, food, the environment, and the workplace. Biomonitoring of chemicals in biological fluids is a tool to determine the individual exposure. Blood protein adducts of xenobiotics are a marker of both exposure and the biologically effective dose. Urinary metabolites and blood metabolites are short term exposure markers. Stable hemoglobin adducts are exposure markers of up to 120 days. Blood protein adducts are formed with many xenobiotics at different sites of the blood proteins. Newer methods apply the techniques developed in the field of proteomics. Larger adducted peptides with 20 amino acids are used for quantitation. Unfortunately, at present the methods do not reach the limits of detection obtained with the methods looking at single amino acid adducts or at chemically cleaved adducts. Therefore, to progress in the field new approaches are needed.
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Jen HH, Kafeenah H, Chang TY, Lin YM, Shan YS, Wu CH, Chen SH. Quantification of the Endogenous Adduction Level on Hemoglobin and Correlation with Albumin Adduction via Proteomics: Multiple Exposure Markers of Catechol Estrogen. J Proteome Res 2021; 20:4248-4257. [PMID: 34406011 DOI: 10.1021/acs.jproteome.1c00097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Catechol estrogens (CEs) are genotoxic metabolites whose detection is challenging due to their low concentrations and high variability in the blood. By intact protein and free CE measurement of the spiked hemolysate, endogenous CEs were revealed to mainly (>99%) exist as hemoglobin (Hb) adducts in red blood cells. In order to detect endogenous CE-Hb adducts, we developed a two-step method that involved protein precipitation and solid phase extraction to purify Hb from red blood cells, and the method was coupled with proteomics using liquid chromatography-tandem mass spectrometry. Using bottom-up proteomics and standard additions, we identified C93 and C112 of Hb-β as the main adduction sites of Hb, and this accounted for CE-induced oxidization of adducted peptides by sample preparation. The non-adducted, adducted, and oxidized tryptic peptides that covered the same Hb-β sequences were targeted by parallel reaction monitoring to determine the adduction level in red blood cells. A quantification limit (S/N < 8) below the endogenous CE-Hb adduction level with relative standard errors that ranged from 5 to 22% was achieved and applied to clinical samples. The human serum albumin (HSA) adduction levels from the same patient were also determined using a previously developed method (Anal. Chem. 2019, 91, 15922-15931). A positive correlation (R2 = 0.673) between the CE-HSA and CE-Hb adduction level was obtained from all clinical samples, and both levels were significantly (p < 0.005) higher for patients with breast cancer compared to healthy controls. However, double indexes derived from the red blood cell and the serum, respectively, provide higher precision and confidence in predicting cancer risk than the single index. This study reported an efficient sample preparation for proteomics-based Hb adducts and revealed the potential of using multiple blood proteins for developing more reliable and specific markers based on protein adductomics.
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Affiliation(s)
- Hung-Hsiang Jen
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Husam Kafeenah
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Ting-Yao Chang
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Yu-Min Lin
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Yan-Shen Shan
- Department of Surgical Medicine, National Cheng Kung University Hospital, Tainan 704, Taiwan
| | - Chih-Hsing Wu
- Department of Family Medicine, National Cheng Kung University Hospital, Tainan 704, Taiwan
| | - Shu-Hui Chen
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
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Hartwig A, Arand M, Epe B, Guth S, Jahnke G, Lampen A, Martus HJ, Monien B, Rietjens IMCM, Schmitz-Spanke S, Schriever-Schwemmer G, Steinberg P, Eisenbrand G. Mode of action-based risk assessment of genotoxic carcinogens. Arch Toxicol 2020; 94:1787-1877. [PMID: 32542409 PMCID: PMC7303094 DOI: 10.1007/s00204-020-02733-2] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 03/31/2020] [Indexed: 12/16/2022]
Abstract
The risk assessment of chemical carcinogens is one major task in toxicology. Even though exposure has been mitigated effectively during the last decades, low levels of carcinogenic substances in food and at the workplace are still present and often not completely avoidable. The distinction between genotoxic and non-genotoxic carcinogens has traditionally been regarded as particularly relevant for risk assessment, with the assumption of the existence of no-effect concentrations (threshold levels) in case of the latter group. In contrast, genotoxic carcinogens, their metabolic precursors and DNA reactive metabolites are considered to represent risk factors at all concentrations since even one or a few DNA lesions may in principle result in mutations and, thus, increase tumour risk. Within the current document, an updated risk evaluation for genotoxic carcinogens is proposed, based on mechanistic knowledge regarding the substance (group) under investigation, and taking into account recent improvements in analytical techniques used to quantify DNA lesions and mutations as well as "omics" approaches. Furthermore, wherever possible and appropriate, special attention is given to the integration of background levels of the same or comparable DNA lesions. Within part A, fundamental considerations highlight the terms hazard and risk with respect to DNA reactivity of genotoxic agents, as compared to non-genotoxic agents. Also, current methodologies used in genetic toxicology as well as in dosimetry of exposure are described. Special focus is given on the elucidation of modes of action (MOA) and on the relation between DNA damage and cancer risk. Part B addresses specific examples of genotoxic carcinogens, including those humans are exposed to exogenously and endogenously, such as formaldehyde, acetaldehyde and the corresponding alcohols as well as some alkylating agents, ethylene oxide, and acrylamide, but also examples resulting from exogenous sources like aflatoxin B1, allylalkoxybenzenes, 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx), benzo[a]pyrene and pyrrolizidine alkaloids. Additionally, special attention is given to some carcinogenic metal compounds, which are considered indirect genotoxins, by accelerating mutagenicity via interactions with the cellular response to DNA damage even at low exposure conditions. Part C finally encompasses conclusions and perspectives, suggesting a refined strategy for the assessment of the carcinogenic risk associated with an exposure to genotoxic compounds and addressing research needs.
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Affiliation(s)
- Andrea Hartwig
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany.
| | - Michael Arand
- Institute of Pharmacology and Toxicology, University of Zurich, 8057, Zurich, Switzerland
| | - Bernd Epe
- Institute of Pharmacy and Biochemistry, University of Mainz, 55099, Mainz, Germany
| | - Sabine Guth
- Department of Toxicology, IfADo-Leibniz Research Centre for Working Environment and Human Factors, TU Dortmund, Ardeystr. 67, 44139, Dortmund, Germany
| | - Gunnar Jahnke
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Alfonso Lampen
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Hans-Jörg Martus
- Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Bernhard Monien
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Simone Schmitz-Spanke
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuremberg, Henkestr. 9-11, 91054, Erlangen, Germany
| | - Gerlinde Schriever-Schwemmer
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Pablo Steinberg
- Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Haid-und-Neu-Str. 9, 76131, Karlsruhe, Germany
| | - Gerhard Eisenbrand
- Retired Senior Professor for Food Chemistry and Toxicology, Kühler Grund 48/1, 69126, Heidelberg, Germany.
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Chen SH, Li CW. Detection and Characterization of Catechol Quinone-Derived Protein Adducts Using Biomolecular Mass Spectrometry. Front Chem 2019; 7:571. [PMID: 31497592 PMCID: PMC6712063 DOI: 10.3389/fchem.2019.00571] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 07/29/2019] [Indexed: 12/14/2022] Open
Abstract
The catechol quinone (CQ) motif is present in many biologically relevant molecules throughout endogenous metabolic products, foods, drugs, and environmental pollutants. The CQ derivatives may undergo Michael addition, and has been shown to yield covalent bonds with nucleophilic sites of cysteine, lysine, or histidine residue of proteins. The CQ-adducted proteins may exhibit cytotoxicity or biological functions different from their un-adducted forms. Identification, characterization, and quantification of relevant protein targets are essential but challenging goals. Mass spectrometry (MS) is well-suited for the analysis of proteins and protein modifications. Technical development of bottom-up proteomics has greatly advanced the field of biomolecular MS, including protein adductomics. This mini-review focuses on the use of biomolecular MS in (1) structural and functional characterization of CQ adduction on standards of proteins, (2) identification of endogenous adduction targets, and (3) quantification of adducted blood proteins as exposure index. The reactivity and outcome of CQ adduction are discussed with emphases on endogenous species, such as dopamine and catechol estrogens. Limitations and advancements in sample preparation, MS instrumentation, and software to facilitate protein adductomics are also discussed.
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Affiliation(s)
- Shu-Hui Chen
- Department of Chemistry, National Cheng Kung University, Tainan, Taiwan
| | - Chun-Wei Li
- Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
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Lin PH, Yang HJ, Hsieh WC, Lin C, Chan YC, Wang YF, Yang YT, Lin KJ, Lin LS, Chen DR. Albumin and hemoglobin adducts of estrogen quinone as biomarkers for early detection of breast cancer. PLoS One 2018; 13:e0201241. [PMID: 30222738 PMCID: PMC6141067 DOI: 10.1371/journal.pone.0201241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 07/11/2018] [Indexed: 12/21/2022] Open
Abstract
Cumulative estrogen concentration is an important determinant of the risk of developing breast cancer. Estrogen carcinogenesis is attributed to the combination of receptor-driven mitogenesis and DNA damage induced by quinonoid metabolites of estrogen. The present study was focused on developing an improved breast cancer prediction model using estrogen quinone-protein adduct concentrations. Blood samples from 152 breast cancer patients and 71 healthy women were collected, and albumin (Alb) and hemoglobin (Hb) adducts of estrogen-3,4-quinone and estrogen-2,3-quinone were extracted and evaluated as potential biomarkers of breast cancer. A multilayer perceptron (MLP) was used as the predictor model and the resultant prediction of breast cancer was more accurate than other existing detection methods. A MLP using the logarithm of the concentrations of the estrogen quinone-derived adducts (four input nodes, 10 hidden nodes, and one output node) was used to predict breast cancer risk with accuracy close to 100% and area under curve (AUC) close to one. The AUC value of one showed that both data sets were separable. We conclude that Alb and Hb adducts of estrogen quinones are promising biomarkers for the early detection of breast cancer.
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Affiliation(s)
- Po-Hsiung Lin
- Department of Environmental Engineering, National Chung Hsing University, South Dist., Taichung, Taiwan, R.O.C
| | - Hui-Ju Yang
- Department of Dermatology, Changhua Christian Hospital, Changhua, Taiwan, R.O.C
| | - Wei-Chung Hsieh
- Department of Internal Medicine, Da-Chien General Hospital, Miaoli, Taiwan, R.O.C
| | - Che Lin
- Comprehensive Breast Cancer Center, Changhua Christian Hospital, Changhua, Taiwan, R.O.C
| | - Ya-Chi Chan
- Cancer Research Center, Department of Research, Changhua Christian Hospital, Changhua, Taiwan, R.O.C
| | - Yu-Fen Wang
- Cancer Research Center, Department of Research, Changhua Christian Hospital, Changhua, Taiwan, R.O.C
| | - Yuan-Ting Yang
- Department of Pharmacy, Changhua Christian Hospital, Changhua, Taiwan, R.O.C
| | - Kuo-Juei Lin
- Department of Surgery, E-Da Hospital, I-Shou University, Kaohsiung, Taiwan, R.O.C
| | - Li-Sheng Lin
- Department of Breast Surgery, the Affiliated Hospital (Group) of Putian University, Putian, Fujian, China
| | - Dar-Ren Chen
- Comprehensive Breast Cancer Center, Changhua Christian Hospital, Changhua, Taiwan, R.O.C
- Cancer Research Center, Department of Research, Changhua Christian Hospital, Changhua, Taiwan, R.O.C
- School of Medicine, Chung Shan Medical University, South Dist., Taichung, Taiwan, R.O.C
- * E-mail:
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Visvanathan K, Yager JD. Ethnic Variations in Estrogen and Its Metabolites: Sufficient to Explain Differences in Breast Cancer Incidence Rates? J Natl Cancer Inst 2016; 108:djw223. [PMID: 27737914 DOI: 10.1093/jnci/djw223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 05/09/2016] [Indexed: 11/15/2022] Open
Affiliation(s)
- Kala Visvanathan
- Departments of Epidemiology (KV) and Environmental Science (JY), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD (KV, JY) Department of Epidemiology (KV) and Department of Environmental Science (JY)
| | - James D Yager
- Departments of Epidemiology (KV) and Environmental Science (JY), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD (KV, JY) Department of Epidemiology (KV) and Department of Environmental Science (JY)
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Hsieh WC, Lin C, Chen DR, Yu WF, Chen GJ, Hu SW, Liu CC, Ge MH, Ruan CS, Chen CY, Lin CH, Lin PH. Genetic polymorphisms in APE1 Asp148Glu(rs3136820) as a modifier of the background levels of abasic sites in human leukocytes derived from breast cancer patients and controls. Breast Cancer 2016; 24:420-426. [PMID: 27539671 DOI: 10.1007/s12282-016-0719-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 08/08/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Apurinic/apyrimidinic (abasic/AP) sites are among the most common endogenous DNA lesions. AP sites, if not repaired, could result in genomic instability as well as chromosome aberrations. Information regarding the direct assay of the number of abasic sites in human leukocytes and its association with risk of breast cancer has not been reported. METHODS In this study, we investigated the association between certain risk factors for breast cancer and the background levels of AP sites in leukocytes derived from 148 Taiwanese women with breast cancer and 140 cancer-free controls. The risk factors studied include age, body mass index (BMI), and polymorphisms of apurinic/apyrimidinic endonuclease (APE1) [APE1 Asp148Glu(rs3136820)]. RESULTS Mean levels of AP sites were estimated to be 23.3 and 50.3 per 106 nucleotides in controls and breast cancer patients, respectively (~twofold, p < 0.001). In subjects with age <50 or BMI < 27 (kg/m2), the levels of AP sites in breast cancer patients were ~2-3-fold greater than those of controls (p < 0.05). Additionally, results from the AP site 3'-cleavage assay indicated that the AP sites detected in both controls and patients were likely to be oxidant-mediated 5'-cleaved AP sites (~61-64 %). The number of AP sites in breast cancer patients was ~twofold greater in subjects with Asp/Glu + Glu/Glugenotypes than those with Asp/Asp genotype (p < 0.001). CONCLUSIONS We confirmed that cumulative body burden of AP sites is a significant predictor of the risk of developing breast cancer and that genetic predisposition and environment factors may modulate the induction of oxidative DNA lesions in breast cancer patients.
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Affiliation(s)
- Wei-Chung Hsieh
- Department of Laboratory Medicine, Da-Chien General Hospital, Miaoli, Taiwan
| | - Che Lin
- Comprehensive Breast Cancer Center, Changhua Christian Hospital, Changhua, Taiwan
| | - Dar-Ren Chen
- Comprehensive Breast Cancer Center, Changhua Christian Hospital, Changhua, Taiwan
| | - Wen-Fa Yu
- Department of Laboratory Medicine, Da-Chien General Hospital, Miaoli, Taiwan
| | - Guan-Jie Chen
- Department of Environmental Engineering, National Chung Hsing University, Taichung, 402, Taiwan
| | - Suh-Woan Hu
- College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Chin-Chen Liu
- Department of Environmental Engineering, National Chung Hsing University, Taichung, 402, Taiwan
| | - Mao-Huei Ge
- Department of Environmental Engineering, National Chung Hsing University, Taichung, 402, Taiwan
| | - Chang-Sin Ruan
- Department of Environmental Engineering, National Chung Hsing University, Taichung, 402, Taiwan
| | - Cheng-You Chen
- Department of Environmental Engineering, National Chung Hsing University, Taichung, 402, Taiwan
| | - Chia-Hua Lin
- Department of Biotechnology, National Formosa University, Yunlin, 63208, Taiwan
| | - Po-Hsiung Lin
- Department of Environmental Engineering, National Chung Hsing University, Taichung, 402, Taiwan.
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Visvanathan K, Yager JD. Ethnic Variations in Estrogen and Its Metabolites: Sufficient to Explain Differences in Breast Cancer Incidence Rates? J Natl Cancer Inst 2016; 108:djw147. [PMID: 27381625 DOI: 10.1093/jnci/djw147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 05/09/2016] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kala Visvanathan
- Departments of Epidemiology (KV) and Environmental Science (JY), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD (KV, JY) Department of Epidemiology (KV) and Department of Environmental Science (JY)
| | - James D Yager
- Departments of Epidemiology (KV) and Environmental Science (JY), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD (KV, JY) Department of Epidemiology (KV) and Department of Environmental Science (JY)
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Yager JD. Mechanisms of estrogen carcinogenesis: The role of E2/E1-quinone metabolites suggests new approaches to preventive intervention--A review. Steroids 2015; 99:56-60. [PMID: 25159108 PMCID: PMC4339663 DOI: 10.1016/j.steroids.2014.08.006] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 06/06/2014] [Indexed: 12/21/2022]
Abstract
UNLABELLED Studies in hamsters, mice and rats have demonstrated that estradiol (E2), its interconvertible metabolite estrone (E1) and their catechol metabolites, in particular 4-hydroxy E2/E1, are carcinogenic in the kidney, uterus and mammary gland. Observational studies and clinical trials consistently show that sustained exposure to E2/E1 is associated with the development of sporadic breast cancer. The weight of evidence supports the contribution of two complementary pathways in the initiation, promotion and progression of breast cancer. One pathway involves activation of nuclear and cytoplasmic signaling pathways through the binding of estrogen to nuclear and membrane-bound estrogen receptors leading to increased cell proliferation. The other pathway involves the oxidative metabolism of E2/E1 to catechols and then reactive quinones that can contribute to oxidative DNA damage and form specific, mutagenic depurinating adducts with adenine and guanine which then in turn can serve as biomarkers for the occurrence of these processes. Both pathways can serve as portals to preventive intervention. Antiestrogens are used clinically to block receptor-mediated signaling to block tumor growth. Various chemopreventive agents such as sulforaphane (SFN) and resveratrol have been shown in cell culture to block oxidative metabolism of E2/E1 and thus prevent DNA damage. Pretreatment of MCF-7 and MCF-10F cells with and inhibitor of catechol-O-methyltransferase (COMT) followed by treatment with E2 or 4-OH E2 caused increased oxidative DNA damage (8-oxo-dG) and depurinating DNA adducts showing the importance of E2-catechol O-methylation by COMT as a protective pathway. E2 treatment of MCF-10A cells with E2 or 4-OH E2 caused an increase in E2-adenine and guanine adducts. Treatment with sulforaphane increased NAD(P)H quinone oxidoreductase 1 (NQO1) and glutathione-S-transferase A1 (GSTA1) expression without affecting expression of catechol-O-methyltransferase (COMT) or cytochrome P450 1B1. Pretreatment with SFN decreased depurinating DNA adducts while increasing levels of 4-OCH3E1/2 and 4-OHE1/2-glutathione conjugates. Treatment of MCF-10F cells with E2 or 4-OH-E2 also caused increased depurinating DNA adducts and neoplastic transformation while pretreatment with resveratrol caused a reduction in adduct levels and neoplastic transformation. Increased levels of estrogen-quinone conjugates and DNA adducts have also been detected in urine of women at increased risk for and with breast cancer. These observations support the notion that targeting the estrogen/estrone metabolism pathway may be another way to reduce breast cancer risk.
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Affiliation(s)
- James D Yager
- Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Rm. 6527, Baltimore, MD 21205, United States.
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