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Bani-Yaseen AD, Kawaguchi T, Price AK, Culbertson CT, Jankowiak R. Integrated microfluidic device for the separation and electrochemical detection of catechol estrogen-derived DNA adducts. Anal Bioanal Chem 2010; 399:519-24. [DOI: 10.1007/s00216-010-4386-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 10/21/2010] [Accepted: 10/24/2010] [Indexed: 10/18/2022]
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Cavalieri EL, Rogan EG. Is bisphenol A a weak carcinogen like the natural estrogens and diethylstilbestrol? IUBMB Life 2010; 62:746-51. [DOI: 10.1002/iub.376] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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53
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Trubicka J, Grabowska-Kłujszo E, Suchy J, Masojć B, Serrano-Fernandez P, Kurzawski G, Cybulski C, Górski B, Huzarski T, Byrski T, Gronwald J, Złowocka E, Kładny J, Banaszkiewicz Z, Wiśniowski R, Kowalska E, Lubinski J, Scott RJ. Variant alleles of the CYP1B1 gene are associated with colorectal cancer susceptibility. BMC Cancer 2010; 10:420. [PMID: 20701755 PMCID: PMC2929240 DOI: 10.1186/1471-2407-10-420] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2009] [Accepted: 08/11/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND CYP1B1 is a P450 enzyme which is involved in the activation of pro-carcinogens to carcinogens as well as sex hormone metabolism. Because differences in the activity of the enzyme have been correlated with variant alleles of single nucleotide polymorphisms (SNPs), it represents an attractive candidate gene for studies into colorectal cancer susceptibility. METHODS We genotyped 597 cancer patients and 597controls for three CYP1B1 SNPs, which have previously been shown to be associated with altered enzymatic activity. Using the three SNPs, eight different haplotypes were constructed. The haplotype frequencies were estimated in cases and controls and then compared. The odds ratio for each tumour type, associated with each haplotype was estimated, with reference to the most common haplotype observed in the controls. RESULTS The three SNPs rs10012, rs1056827 and rs1056836 alone did not provide any significant evidence of association with colorectal cancer risk. Haplotypes of rs1056827 and rs10012 or rs1056827 and rs1056836 revealed an association with colorectal cancer which was significantly stronger in the homozygous carriers. One haplotype was under represented in the colorectal cancer patient group compared to the control population suggesting a protective effect. CONCLUSION Genetic variants within the CYP1B1 that are associated with altered function appear to influence susceptibility to a colorectal cancer in Poland. Three haplotypes were associated with altered cancer risk; one conferred protection and two were associated with an increased risk of disease. These observations should be confirmed in other populations.
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Affiliation(s)
- Joanna Trubicka
- Department of Genetics and Pathology, International Hereditary Cancer Center, Pomeranian Medical University, Szczecin, Poland
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Zahid M, Saeed M, Ali MF, Rogan EG, Cavalieri EL. N-acetylcysteine blocks formation of cancer-initiating estrogen-DNA adducts in cells. Free Radic Biol Med 2010; 49:392-400. [PMID: 20472053 PMCID: PMC2900421 DOI: 10.1016/j.freeradbiomed.2010.04.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 03/31/2010] [Accepted: 04/26/2010] [Indexed: 12/29/2022]
Abstract
Catechol estrogens, especially 4-hydroxylated metabolites of 17beta-estradiol (E(2)), are responsible for estrogen-induced carcinogenesis. 4-Hydroxyestradiol (4-OHE(2)), a major metabolite of E(2) formed preferentially by cytochrome P-450 1B1, is oxidized to E(2)-3,4-quinone, which can react with DNA to yield the depurinating adducts 4-OHE(2)-1-N3Ade and 4-OHE(2)-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-OHE(2) or its reactive metabolite, E(2)-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-alpha. 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.
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Affiliation(s)
- Muhammad Zahid
- Eppley Institute for Research in Cancer and Allied Diseases, College of Public Health, University of Nebraska Medical Center, Omaha, NE 68198, USA
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La Merrill M, Harper R, Birnbaum LS, Cardiff RD, Threadgill DW. Maternal dioxin exposure combined with a diet high in fat increases mammary cancer incidence in mice. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:596-601. [PMID: 20435547 PMCID: PMC2866672 DOI: 10.1289/ehp.0901047] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 12/09/2009] [Indexed: 05/24/2023]
Abstract
BACKGROUND RESULTS from previous studies have suggested that breast cancer risk correlates with total lifetime exposure to estrogens and that early-life 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure or diets high in fat can also increase cancer risk. OBJECTIVES Because both TCDD and diet affect the estrogen pathway, we examined how TCDD and a high-fat diet (HFD) interact to alter breast cancer susceptibility. METHODS We exposed pregnant female FVB/NJ mice (12.5 days postcoitus) to 1 microg/kg TCDD or vehicle; at parturition, the dams were randomly assigned to a low-fat diet (LFD) or a high-fat diet (HFD). Female offspring were maintained on the same diets after weaning and were exposed to 7,12-dimethylbenz[a]anthracene on postnatal days (PNDs) 35, 49, and 63 to initiate mammary tumors. A second cohort of females was treated identically until PND35 or PND49, when mammary gland morphology was examined, or PND50, when mammary gland mRNA was analyzed. RESULTS We found that maternal TCDD exposure doubled mammary tumor incidence only in mice fed the HFD. Among HFD-fed mice, maternal TCDD exposure caused rapid mammary development with increased Cyp1b1 (cytochrome P450 1B1) expression and decreased Comt (catechol-O-methyltransferase) expression in mammary tissue. Maternal TCDD exposure also increased mammary tumor Cyp1b1 expression. CONCLUSIONS Our data suggest that the HFD increases sensitivity to maternal TCDD exposure, resulting in increased breast cancer incidence, by changing metabolism capability. These results provide a mechanism to explain epidemiological data linking early-life TCDD exposure and diets high in fat to increased risk for breast cancer in humans.
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Affiliation(s)
- Michele La Merrill
- Curriculum in Toxicology, Department of Genetics, Center for Environmental and Health Susceptibility, Lineberger Cancer Center, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rachel Harper
- Curriculum in Toxicology, Department of Genetics, Center for Environmental and Health Susceptibility, Lineberger Cancer Center, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Linda S. Birnbaum
- Experimental Toxicology Division, U.S. Environmental Protection Agency, Office of Research and Development/National Health and Environmental Effects Research Laboratory, Research Triangle Park, North Carolina, USA
- National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA
| | - Robert D. Cardiff
- Center for Comparative Medicine, Department of Pathology and Laboratory Medicine, University of California–Davis, Davis, California, USA
| | - David W. Threadgill
- Curriculum in Toxicology, Department of Genetics, Center for Environmental and Health Susceptibility, Lineberger Cancer Center, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, USA
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Cavalieri EL, Rogan EG. Depurinating estrogen-DNA adducts in the etiology and prevention of breast and other human cancers. Future Oncol 2010; 6:75-91. [PMID: 20021210 DOI: 10.2217/fon.09.137] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Experiments on estrogen metabolism, formation of DNA adducts, mutagenicity, cell transformation and carcinogenicity have led to and supported the hypothesis that the reaction of specific estrogen metabolites, mostly the electrophilic catechol estrogen-3,4-quinones, with DNA can generate the critical mutations to initiate breast and other human cancers. Analysis of depurinating estrogen-DNA adducts in urine demonstrates that women at high risk of, or with breast cancer, have high levels of the adducts, indicating a critical role for adduct formation in breast cancer initiation. Men with prostate cancer or non-Hodgkin lymphoma also have high levels of estrogen-DNA adducts. This knowledge of the first step in cancer initiation suggests the use of specific antioxidants that can block formation of the adducts by chemical and biochemical mechanisms. Two antioxidants, N-acetylcysteine and resveratrol, are prime candidates to prevent breast and other human cancers because in various M in vitro and in vivo experiments, they reduce the formation of estrogen-DNA adducts.
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Affiliation(s)
- Ercole L Cavalieri
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA.
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Gaikwad NW, Yang L, Weisenburger DD, Vose J, Beseler C, Rogan EG, Cavalieri EL. Urinary biomarkers suggest that estrogen-DNA adducts may play a role in the aetiology of non-Hodgkin lymphoma. Biomarkers 2010; 14:502-12. [PMID: 19863189 DOI: 10.3109/13547500903121715] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A variety of evidence suggests that estrogens may induce non-Hodgkin lymphoma (NHL). The reaction of catechol estrogen quinones with DNA to form depurinating estrogen-DNA adducts is hypothesized to initiate this process. These adducts are released from DNA, shed from cells into the bloodstream and excreted in urine. The aim of this study was to determine whether or not the depurinating estrogen-DNA adducts might be involved in the aetiology of human NHL. Estrogen metabolites, conjugates and depurinating DNA adducts were identified and quantified in spot urine samples from 15 men with NHL and 30 healthy control men by using ultraperformance liquid chromatography/tandem mass spectrometry. The levels of estrogen-DNA adducts were significantly higher in the men with NHL than in the healthy control men. Thus, formation of estrogen-DNA adducts may play a critical role in the aetiology of NHL, and these adducts could be potential biomarkers of NHL risk.
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Affiliation(s)
- Nilesh W Gaikwad
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-6805, USA
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Circulating sex steroids and breast cancer risk in premenopausal women. Discov Oncol 2010; 1:2-10. [PMID: 21761346 DOI: 10.1007/s12672-009-0003-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 12/17/2009] [Indexed: 12/21/2022] Open
Abstract
Evidence from both laboratory and epidemiologic studies indicate a key role of hormones in the etiology of breast cancer. In epidemiologic studies, indirect data, including the consistent associations observed between reproductive factors and breast cancer risk, support an important contribution of hormones to risk. Recently, the associations between circulating hormones in premenopausal women and subsequent risk of breast cancer have been evaluated. To date, both positive and null associations have been observed for estrogens and inverse and null associations for progesterone with breast cancer risk. For estrogens, the relationships may vary by menstrual cycle phase (e.g., follicular versus luteal phase), although this requires confirmation. Few studies have evaluated estrogen metabolites in relation to breast cancer risk; hence, no conclusions can yet be drawn. Findings for the largely adrenal-derived dehydroepiandrosterone (DHEA) and DHEA sulfate also are inconsistent and may vary by age. However, relatively consistent positive associations have been observed between testosterone (or free testosterone) levels and breast cancer risk; these associations are of similar magnitude to those confirmed among postmenopausal women. In this review, we summarize current evidence and identify gaps and inconsistencies that need to be addressed in future studies of sex steroids and premenopausal breast cancer risk.
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Zahid M, Saeed M, Rogan EG, Cavalieri EL. Benzene and dopamine catechol quinones could initiate cancer or neurogenic disease. Free Radic Biol Med 2010; 48:318-24. [PMID: 19909805 PMCID: PMC2818485 DOI: 10.1016/j.freeradbiomed.2009.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 10/22/2009] [Accepted: 11/04/2009] [Indexed: 01/21/2023]
Abstract
Catechol quinones of estrogens react with DNA by 1,4-Michael addition to form depurinating N3Ade and N7Gua adducts. Loss of these adducts from DNA creates apurinic sites that can generate mutations leading to cancer initiation. We compared the reactions of the catechol quinones of the leukemogenic benzene (CAT-Q) and N-acetyldopamine (NADA-Q) with 2'-deoxyguanosine (dG) or DNA. NADA was used to prevent intramolecular cyclization of dopamine quinone. Reaction of CAT-Q or NADA-Q with dG at pH 4 afforded CAT-4-N7dG or NADA-6-N7dG, which lost deoxyribose with a half-life of 3 h to form CAT-4-N7Gua or 4 h to form NADA-6-N7Gua. When CAT-Q or NADA-Q was reacted with DNA, N3Ade adducts were formed and lost from DNA instantaneously, whereas N7Gua adducts were lost over several hours. The maximum yield of adducts in the reaction of CAT-Q or NADA-Q with DNA at pH 4 to 7 was at pH 4. When tyrosinase-activated CAT or NADA was reacted with DNA at pH 5 to 8, adduct levels were much higher (10- to 15-fold), and the highest yield was at pH 5. Reaction of catechol quinones of natural and synthetic estrogens, benzene, naphthalene, and dopamine with DNA to form depurinating adducts is a common feature that may lead to initiation of cancer or neurodegenerative disease.
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Affiliation(s)
- Muhammad Zahid
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
| | - Muhammad Saeed
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
| | - Eleanor G. Rogan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
- Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE
| | - Ercole L. Cavalieri
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
- Ercole L. Cavalieri, Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 658198-6805, Telephone: 402-559-7237, Fax: 402-559-8068,
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Seeger H, Mueck AO. Are estradiol metabolites involved in gynaecological carcinogenesis? Horm Mol Biol Clin Investig 2010; 1:111-6. [PMID: 25961977 DOI: 10.1515/hmbci.2010.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 10/21/2009] [Indexed: 11/15/2022]
Abstract
Certain estradiol metabolites are biologically active, sometimes several times more potent than their parent substance. Highly sophisticated laboratory methods allow us to understand oestrogenic effects as a net effect of the corresponding metabolite pattern. Currently, research is focused on the anticancerogenic effects of 2-hydroxyestrone and particularly 2-methoxyestradiol, as well as the possible carcinogenic properties of 4-hydroxyoestrogens and 16α-hydroxyestrone. The clinical relevance of these activities, demonstrated in in-vitro and animal experiments, remains unclear - it is proven, however, that the metabolite production can be altered in certain malignancies such as endometrial-, breast- and cervical carcinoma. Clinical studies, including our studies, have demonstrated a negative correlation between the ratio of 2-hydroxyestrone to 16α-hydroxyestrone and breast cancer risk. However, the design and interpretation of such studies should consider factors influencing metabolic pattern such as diet, physical activity, smoking, as well as internal diseases and certain drugs.
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Depurination of Nucleosides and Calf Thymus DNA Induced by 2-Bromopropane at the Physiological Condition. B KOREAN CHEM SOC 2009. [DOI: 10.5012/bkcs.2009.30.10.2309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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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; 117:56-66. [PMID: 19628038 PMCID: PMC4425209 DOI: 10.1016/j.jsbmb.2009.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 06/25/2009] [Accepted: 07/14/2009] [Indexed: 12/01/2022]
Abstract
Estrogens (estrone, E(1); estradiol, E(2)) are oxidized in the breast first to catechols and then to form two ortho-quinones (E(1/2)-3,4-Q) that react with DNA to form depurinating adducts, which lead to mutations associated with breast cancer. NAD(P)H:quinone oxidoreductase 1 (NQO1) reduces these quinones back to catechols, and thus may protect against this mechanism. We examined whether the inheritance of two polymorphic variants of NQO1 (Pro187Ser or Arg139Trp) would result in poor reduction of E(1/2)-3,4-Q in normal human mammary epithelial cells (MCF-10F) and increased depurinating adduct formation. An isogenic set of stably transfected normal human breast epithelial cells (MCF-10F) that express a truncated (135Stop), the wild-type, the 139Trp variant or the 187Ser variant of human NQO1 cDNA was constructed. MCF-10F cells showed a low endogenous NQO1 activity. NQO1 expression was examined by RT-PCR and Western blotting, and catalytic activity of reducing E(2)-3,4-Q to 4-hydroxyE(1/2) and associated changes in the levels of quinone conjugates (4-methoxyE(1/2), 4-OHE(1/2)-2-glutathione, 4-OHE(1/2)-2-Cys and 4-OHE(1/2)-2-N-acetylcysteine) and depurinating DNA adducts (4-OHE(1/2)-1-N3Ade and 4-OHE(1/2)-1-N7Gua) were examined by HPLC with electrochemical detection, as well as by ultra-performance liquid chromatography with tandem mass spectrometry. The polymorphic variants transcribed comparably to the wild-type NQO1, but produced approximately 2-fold lower levels of the protein, suggesting that the variant proteins may become degraded. E(1/2)-3,4-Q toxicity to MCF-10F cells (IC50=24.74 microM) was increased (IC50=3.7 microM) by Ro41-0960 (3 microM), a catechol-O-methyltransferase inhibitor. Cells expressing polymorphic NQO1 treated with E(2)-3,4-Q with or without added Ro41-0960, showed lower ability to reduce the quinone ( approximately 50% lower levels of the free catechols and approximately 3-fold lower levels of methylated catechols) compared to the wild-type enzyme. The increased availability of the quinones in these cells did not result in greater glutathione conjugation. Instead, there was increased (2.5-fold) formation of the depurinating DNA adducts. Addition of Ro41-0960 increased the amounts of free catechols, quinone conjugates and depurinating DNA adducts. NQO1 polymorphic variants (Arg139Trp and Pro187Ser) were poor reducers of estrogen-3,4-quinones, which caused increased formation of estrogen-DNA adduct formation in MCF-10F cells. Therefore, the inheritance of these NQO1 polymorphisms may favor the estrogen genotoxic mechanism of breast cancer.
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Affiliation(s)
- Seema Singh
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, United States
| | - Muhammad Zahid
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, United States
| | - Muhammad Saeed
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, United States
| | - Nilesh W. Gaikwad
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, United States
| | - Jane L. Meza
- Preventive and Societal Medicine, 984350 Nebraska Medical Center, Omaha, NE 68198-4350, United States
| | - Ercole L. Cavalieri
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, United States
| | - Eleanor G. Rogan
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, United States
- Department of Environmental, Agricultural and Occupational Health, College of Public Health, Nebraska Medical Center, Omaha, NE 68198-5110, United States
| | - Dhrubajyoti Chakravarti
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, United States
- Corresponding author. Tel.: +1 402 559 2951; fax: +1 402 559 8068. (D. Chakravarti)
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Saeed M, Higginbotham S, Gaikwad N, Chakravarti D, Rogan E, Cavalieri E. Depurinating naphthalene-DNA adducts in mouse skin related to cancer initiation. Free Radic Biol Med 2009; 47:1075-81. [PMID: 19619639 PMCID: PMC4424927 DOI: 10.1016/j.freeradbiomed.2009.07.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 07/10/2009] [Accepted: 07/13/2009] [Indexed: 11/15/2022]
Abstract
Naphthalene has been shown to be a weak carcinogen in rats. To investigate its mechanism of metabolic activation and cancer initiation, mice were topically treated with naphthalene or one of its metabolites, 1-naphthol, 1,2-dihydrodiolnaphthalene (1,2-DDN), 1,2-dihydroxynaphthalene (1,2-DHN), and 1,2-naphthoquinone (1,2-NQ). After 4 h, the mice were sacrificed, the treated skin was excised, and the depurinating and stable DNA adducts were analyzed. The depurinating adducts were identified and quantified by ultraperformance liquid chromatography/tandem mass spectrometry, whereas the stable adducts were quantified by (32)P-postlabeling. For comparison, the stable adducts formed when a mixture of the four deoxyribonucleoside monophosphates was treated with 1,2-NQ or enzyme-activated naphthalene were also analyzed. The depurinating adducts 1,2-DHN-1-N3Ade and 1,2-DHN-1-N7Gua arise from reaction of 1,2-NQ with DNA. Similarly, the major stable adducts appear to derive from the 1,2-NQ. The depurinating DNA adducts are, in general, the most abundant. Therefore, naphthalene undergoes metabolic activation to the electrophilic ortho-quinone, 1,2-NQ, which reacts with DNA to form depurinating adducts. This is the same mechanism as other weak carcinogens, such as the natural and synthetic estrogens, and benzene.
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Affiliation(s)
- Muhammad Saeed
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
| | - Sheila Higginbotham
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
| | - Nilesh Gaikwad
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
| | - Dhrubajyoti Chakravarti
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
| | - Eleanor Rogan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
| | - Ercole Cavalieri
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
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Chakravarti D, Zahid M, Backora M, Myers EM, Gaikwad N, Weisenburger DD, Cavalieri EL, Rogan EG, Joshi SS. Ortho-quinones of benzene and estrogens induce hyperproliferation of human peripheral blood mononuclear cells. Leuk Lymphoma 2009; 47:2635-44. [PMID: 17169809 DOI: 10.1080/10428190600931937] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Benzene is a known leukemogen. It has been hypothesized that benzene and natural estrogens initiate cancer by forming ortho-quinones (catechol quinones) that react with DNA in cells. These quinones form depurinating DNA adducts that generate the mutations leading to cancer. This study examined whether the treatment of normal human peripheral blood mononuclear cells with the ortho-quinones of benzene or estradiol would form DNA adducts and elicit an alteration in the proliferation of these cells. Both estradiol-3,4-quinone and benzene ortho-quinone formed depurinating DNA adducts and significantly increased the mitogen-induced proliferation of normal blood mononuclear cells. Immunophenotyping of the estradiol-3,4-quinone-treated blood cells indicated that monocyte/macrophage, natural killer and T-cells were particularly prone to hyperproliferation. Thus, DNA damage induced by the ortho-quinones of benzene and estradiol may promote the growth of human blood mononuclear cells, including those that appear in large numbers in leukemia and lymphoma.
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Affiliation(s)
- Dhrubajyoti Chakravarti
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
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Lin PH, Chen DR, Wang TW, Lin CH, Chuang MC. Investigation of the cumulative tissue doses of naphthoquinones in human serum using protein adducts as biomarker of exposure. Chem Biol Interact 2009; 181:107-14. [PMID: 19505452 DOI: 10.1016/j.cbi.2009.05.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Revised: 05/20/2009] [Accepted: 05/21/2009] [Indexed: 10/20/2022]
Abstract
Both 1,2-naphthoquinone (1,2-NPQ) and 1,4-naphthoquinone (1,4-NPQ) are reactive metabolites of naphthalene that are thought to be responsible for the naphthalene-induced cytotoxicity and genotoxicity. The aim of this study was to investigate the cumulative tissue dose of 1,2-NPQ and 1,4-NPQ in human serum derived from blood donors in Taiwan via measurements of albumin adducts by a methodology, which employs trifluoroacetic acid anhydride and methanesulfonic acid to selectively cleave cysteinyl adducts on proteins. Both 1,2-NPQ and 1,4-NPQ adducts were detected in all male and female subjects (n=22). The median levels of 1,2-NPQ adduct in human subjects were estimated to be 268 (range 139-857) and 203 (range 128-1352) (pmol/g) in male (n=11) and female (n=11) subjects, respectively. In contrast, the median levels of 1,4-NPQ adduct were estimated to be 45.0 (range 22.0-117) and 38.9 (range 21.5-172) (pmol/g) in male and female subjects, respectively. We noticed that levels of 1,2-NPQ adduct were significantly correlated with those of 1,4-NPQ adduct (correlation coefficient r=0.643, p<0.01). Results from in vitro experiments confirmed that the production of naphthoquinones-derived adducts on serum albumin increased with increased concentration of naphthoquinones (0-100 microM). Linear relationships were observed over the range of concentration. Time-course experiments suggested that both 1,2-NPQ and 1,4-NPQ-derived adducts rapidly reached maximum values at 10 min mark and remained constant thereafter. The reaction rate constant analyses indicated that the second-order rate constants, representing in vitro reactions between naphthoquinones and cysteine residues of serum albumin, were estimated to be 0.0044/0.0002L(gprotein)(-1)h(-1), respectively. Overall, the cumulative tissue doses of 1,4-NPQ (217-316 nM h) in male and female subjects were approximately 3-fold greater than those of 1,2-NPQ (76-98 nM h) in the study population. The initial concentrations of serum 1,2-NPQ and 1,4-NPQ in the study population were estimated to be between 145-188 and 807-1175 nM, respectively. We conclude that the relatively large amounts of naphthoquinones present in human serum may point to toxicological consequences.
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Affiliation(s)
- Po-Hsiung Lin
- Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan.
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66
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Makridakis NM, Caldas Ferraz LF, Reichardt JKV. Genomic analysis of cancer tissue reveals that somatic mutations commonly occur in a specific motif. Hum Mutat 2009; 30:39-48. [PMID: 18623241 DOI: 10.1002/humu.20810] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Somatic mutations are hallmarks of cancer progression. We sequenced 26 matched human prostate tumor and constitutional DNA samples for somatic alterations in the SRD5A2, HPRT, and HSD3B2 genes, and identified 71 nucleotide substitutions. Of these substitutions, 79% (56/71) occur within a WKVnRRRnVWK sequence (a novel motif we call THEMIS [from the ancient Greek goddess of prophecy]: W=A/T, K=G/T, V=G/A/C, R=purine (A/G), and n=any nucleotide), with one mismatch allowed. Literature searches identified this motif with one mismatch allowed in 66% (37/56) of the somatic prostate cancer mutations and in 74% (90/122) of the somatic breast cancer mutations found in all human genes analyzed. We also found the THEMIS motif with one allowed mismatch in 88% (23/26) of the ras1 gene somatic mutations formed in the sensitive to skin carcinogenesis (SENCAR) mouse model, after induction of error-prone DNA repair following mutagenic treatment. The high prevalence of the motif in each of the above mentioned cases cannot be explained by chance (P<0.046). We further identified 27 somatic mutations in the error-prone DNA polymerase genes pol eta, pol kappa, and pol beta in these prostate cancer patients. The data suggest that most somatic nucleotide substitutions in human cancer may occur in sites that conform to the THEMIS motif. These mutations may be caused by "mutator" mutations in error-prone DNA polymerase genes.
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Affiliation(s)
- Nick M Makridakis
- Department of Biochemistry and Molecular Biology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California (USC), Los Angeles, California, USA.
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67
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Saeed M, Rogan E, Cavalieri E. Mechanism of metabolic activation and DNA adduct formation by the human carcinogen diethylstilbestrol: the defining link to natural estrogens. Int J Cancer 2009; 124:1276-84. [PMID: 19089919 PMCID: PMC2814601 DOI: 10.1002/ijc.24113] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Diethylstilbestrol (DES) is a human carcinogen, based on sufficient epidemiological evidence. DES is mainly metabolized to its catechol, 3'-hydroxyDES (3'-OH-DES), which can further oxidize to DES-3',4'-quinone (DES-3',4'-Q). Similarly to estradiol-3,4-quinone, the reaction of DES-3',4'-Q with DNA would form the depurinating 3'-OH-DES-6'-N3Ade and 3'-OH-DES-6'-N7Gua adducts. To prove this hypothesis, synthesis of DES-3',4'-Q by oxidation of 3'-OH-DES with Ag(2)O was tried; this failed due to instantaneous formation of a spiro-quinone. Oxidation of 3'-OH-DES by lactoperoxidase or tyrosinase in the presence of DNA led to the formation of 3'-OH-DES-6'-N3Ade and 3'-OH-DES-6'-N7Gua adducts. These adducts were tentatively identified by LC-MS/MS as 3'-OH-DES-6'-N3Ade, m/z = 418 [M+H](+), and 3'-OH-DES-6'-N7Gua, m/z = 434 [M+H](+). Demonstration of their structures derived from their oxidation by MnO(2) to the DES quinone adducts and subsequent tautomerization to the dienestrol (DIES) catechol adducts, which are identical to the standard 3'-OH-DIES-6'-N3Ade, m/z = 416 [M+H](+), and 3'-OH-DIES-6'-N7Gua, m/z = 432 [M+H](+), adducts. The reaction of DIES-3',4'-Q or lactoperoxidase-activated 3'-OH-DIES with DNA did not produce any depurinating adducts, due to the dienic chain being perpendicular to the phenyl planes, which impedes the intercalation of DIES into the DNA. Enzymic oxidation of 3'-OH-DES suggests that the catechol of DES intercalates into DNA and is then oxidized to its quinone to yield N3Ade and N7Gua adducts. These results suggest that the common denominator of tumor initiation by the synthetic estrogen DES and the natural estrogen estradiol is formation of their catechol quinones, which react with DNA to afford the depurinating N3Ade and N7Gua adducts.
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Affiliation(s)
- Muhammad Saeed
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-6805, USA
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68
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Park SA, Na HK, Kim EH, Cha YN, Surh YJ. 4-Hydroxyestradiol Induces Anchorage-Independent Growth of Human Mammary Epithelial Cells via Activation of IκB Kinase: Potential Role of Reactive Oxygen Species. Cancer Res 2009; 69:2416-24. [DOI: 10.1158/0008-5472.can-08-2177] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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69
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Gaikwad NW, Yang L, Rogan EG, Cavalieri EL. Evidence for NQO2-mediated reduction of the carcinogenic estrogen ortho-quinones. Free Radic Biol Med 2009; 46:253-62. [PMID: 18996184 PMCID: PMC2746554 DOI: 10.1016/j.freeradbiomed.2008.10.029] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 09/30/2008] [Accepted: 10/06/2008] [Indexed: 12/18/2022]
Abstract
The physiological function of NAD(P)H:quinone oxidoreductase (NQO1, DT-diaphorase) is to detoxify potentially reactive quinones by direct transfer of two electrons. A similar detoxification role has not been established for its homologue NRH:quinone oxidoreductase 2 (NQO2). Estrogen quinones, including estradiol(E(2))-3,4-Q, generated by estrogen metabolism, are thought to be responsible for estrogen-initiated carcinogenesis. In this investigation, we have shown for the first time that NQO2 catalyzes the reduction of electrophilic estrogen quinones and thereby may act as a detoxification enzyme. ESI and MALDI mass spectrometric binding studies involving E(2)-3,4-Q with NQO2 clearly support the formation of an enzyme-substrate physical complex. The problem of spontaneous reduction of substrate by cofactor, benzyldihydronicotinamide riboside (BNAH), was successfully overcome by taking advantage of the ping-pong mechanism of NQO2 catalysis. The involvement of the enzyme in the reduction of E(2)-3,4-Q was further supported by addition of the inhibitor quercetin to the assay mixture. NQO2 is a newly discovered binding site (MT3) of melatonin. However, addition of melatonin to the assay mixture did not affect the catalytic activity of NQO2. Preliminary kinetic studies show that NQO2 is faster in reducing estrogen quinones than its homologue NQO1. Both UV and liquid chromatography-tandem mass spectrometry assays unequivocally corroborate the reduction of estrogen ortho-quinones by NQO2, indicating that it could be a novel target for prevention of breast cancer initiation.
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Affiliation(s)
| | | | | | - Ercole L. Cavalieri
- Corresponding Author: Ercole L. Cavalieri, Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-6805, Tel. 402-559-7237, Fax 402-559-8068, e-mail:
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70
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Gaikwad NW, Yang L, Pruthi S, Ingle JN, Sandhu N, Rogan EG, Cavalieri EL. Urine biomarkers of risk in the molecular etiology of breast cancer. BREAST CANCER-BASIC AND CLINICAL RESEARCH 2009; 3:1-8. [PMID: 21556245 PMCID: PMC3086311 DOI: 10.4137/bcbcr.s2112] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Endogenous estrogens can be bio-activated to endogenous carcinogens via formation of estrogen quinones. Estrogen-3,4-quinones react with DNA to form mutagenic depurinating estrogen-DNA adducts. The carcinogenicity of endogenous estrogens is related to unbalanced estrogen metabolism leading to excess estrogen quinones and formation of depurinating DNA adducts. The present studies were initiated to confirm that relatively high levels of depurinating estrogen-DNA adducts are present in women at high risk for breast cancer or diagnosed with the disease. These adducts may be biomarkers for early detection of breast cancer risk. The estrogen metabolites, conjugates and depurinating DNA adducts were identified and quantified by using ultraperformance liquid chromatography/tandem mass spectrometry to analyze urine samples from 40 healthy control women, 40 high-risk women and 40 women with newly diagnosed breast cancer. Estrogen metabolism was shifted from protective methoxylation and conjugation pathways in healthy control women towards activating pathways leading to formation of depurinating DNA adducts in women at high risk or with breast cancer. These results support the hypothesis that breast cancer is initiated by mutations derived from depurination of estrogen-DNA adducts. Therefore, relative levels of depurinating estrogen-DNA adducts could become biomarkers for early detection of breast cancer risk and aid in determining preventive strategies.
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Affiliation(s)
- Nilesh W Gaikwad
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805
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71
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Eliassen AH, Missmer SA, Tworoger SS, Hankinson SE. Circulating 2-hydroxy- and 16alpha-hydroxy estrone levels and risk of breast cancer among postmenopausal women. Cancer Epidemiol Biomarkers Prev 2008; 17:2029-35. [PMID: 18708395 DOI: 10.1158/1055-9965.epi-08-0262] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Circulating estrogens are associated with breast cancer risk in postmenopausal women. Given that estrogen metabolites are potentially both mitogenic and genotoxic, it is possible that plasma levels of estrogen metabolites are related to breast cancer risk. We conducted a prospective, nested case-control study within the Nurses' Health Study. Blood samples, collected in 1989 to 1990, were assayed for 2-OH and 16alpha-OH estrone among 340 cases and 677 matched controls not taking postmenopausal hormones. Multivariate relative risks (RR) and 95% confidence intervals (95% CI) were calculated by conditional logistic regression, adjusting for breast cancer risk factors. Neither 2-OH nor 16alpha-OH estrone concentrations were significantly associated with breast cancer risk overall (top versus bottom quartile: RR, 1.19; 95% CI, 0.80-1.79; P(trend) = 0.40 for 2-OH estrone and RR, 1.04; 95% CI, 0.71-1.53; P(trend) = 0.81 for 16alpha-OH estrone). The ratio between the two metabolites (2-OH:16alpha-OH estrone) was similarly unrelated to risk overall (1.30; 95% CI, 0.87-1.95; P(trend) = 0.35). Although no associations were detected among women with estrogen receptor (ER)-positive/progesterone receptor (PR)-positive tumors, significant positive associations were observed for 2-OH estrone and the 2-OH:16alpha-OH estrone ratio among women with ER-negative/PR-negative tumors (RR, 3.65; 95% CI, 1.23-10.81; P(trend) = 0.01; P(heterogeneity) = 0.02 for 2-OH estrone; RR, 3.70; 95% CI, 1.24-11.09; P(trend) = 0.004; P(heterogeneity) = 0.005 for 2-OH:16alpha-OH estrone). These data do not support the hypothesized inverse associations with 2-OH estrone and the 2-OH:16alpha-OH estrone ratio or the hypothesized positive association with 16alpha-OH estrone. The significant positive associations with 2-OH estrone and the 2-OH:16-OH estrone ratio among women with ER-negative/PR-negative tumors needs to be replicated in future studies.
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Affiliation(s)
- A Heather Eliassen
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA.
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72
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Zahid M, Gaikwad NW, Ali MF, Lu F, Saeed M, Yang L, Rogan EG, Cavalieri EL. Prevention of estrogen-DNA adduct formation in MCF-10F cells by resveratrol. Free Radic Biol Med 2008; 45:136-45. [PMID: 18423413 PMCID: PMC2494714 DOI: 10.1016/j.freeradbiomed.2008.03.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 03/06/2008] [Accepted: 03/25/2008] [Indexed: 01/19/2023]
Abstract
Resveratrol (Resv), a natural occurring phytolexin present in grapes and other foods, possesses chemopreventive effects revealed by its striking modulation of diverse cellular events associated with tumor initiation, promotion, and progression. Catechol estrogens generated in the metabolism of estrogens are oxidized to catechol quinones that react with DNA to form predominantly depurinating estrogen-DNA adducts. This event can generate the mutations responsible for cancer initiation. In this regard, Resv acts as both an antioxidant and an inducer of the phase II enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1). In this report, we present the effects of Resv on the metabolism of estrogens in normal breast epithelial cells (MCF-10F) treated with 4-hydroxyestradiol (4-OHE(2)) or estradiol-3,4-quinone (E(2)-3,4-Q). Resv induced NQO1 in a dose- and time-dependent manner, but did not affect the expression of catechol-O-methyltransferase. Ultraperformance liquid chromatography/tandem mass spectrometry was used to determine the effects of Resv on estrogen metabolism. Preincubation of the cells with Resv for 48 h decreased the formation of depurinating estrogen-DNA adducts from 4-OHE(2) or E(2)-3,4-Q and increased formation of methoxycatechol estrogens. When Resv was also present with the 4-OHE(2) or E(2)-3,4-Q, even greater increases in methoxycatechol estrogens were observed, and the DNA adducts were undetectable. We conclude that Resv can protect breast cells from carcinogenic estrogen metabolites, suggesting that it could be used in breast cancer prevention.
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Affiliation(s)
| | | | | | | | | | | | | | - Ercole L. Cavalieri
- *To whom correspondence should be addressed. Ercole L. Cavalieri, Eppley Institute for Research in Cancer and Allied Diseases, UNMC, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, phone 402-559-7237, fax 402-559-8068, e-mail,
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73
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Possible genotoxic modes of action for naphthalene. Regul Toxicol Pharmacol 2008; 51:S43-50. [DOI: 10.1016/j.yrtph.2007.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 11/20/2007] [Accepted: 12/03/2007] [Indexed: 11/23/2022]
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74
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Lin PH, Lin CH, Huang CC, Fang JP, Chuang MC. 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Modulates the Induction of DNA Strand Breaks and Poly(ADP-ribose) Polymerase-1 Activation by 17β-Estradiol in Human Breast Carcinoma Cells Through Alteration of CYP1A1 and CYP1B1 Expression. Chem Res Toxicol 2008; 21:1337-47. [DOI: 10.1021/tx700396d] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Po-Hsiung Lin
- Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan
| | - Chia-Hua Lin
- Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan
| | - Chuan-Chen Huang
- Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan
| | - Ju-Pin Fang
- Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan
| | - Ming-Chieh Chuang
- Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan
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75
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Stack DE, Li G, Hill A, Hoffman N. Mechanistic insights into the Michael addition of deoxyguanosine to catechol estrogen-3,4-quinones. Chem Res Toxicol 2008; 21:1415-25. [PMID: 18547067 DOI: 10.1021/tx800071u] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction of catechol estrogen quinones with DNA to produce the depurinating adducts, 4-OHE 2(E 1)-1-N7Gua and 4-OHE 2(E 1)-1-N3Ade, has been linked to the initiation of breast and other human cancers. A better understanding into the mechanism of how these adducts are formed would be useful to studies aimed at correlating adduct formation to DNA damage. Possible reaction intermediates, produced as a result of Michael addition of deoxyguanosine (dG) to catechol estrogen-3,4-quninones, have been modeled using density functional theory to determine likely intermediates on the potential energy surface (PES) of this reaction. Specifically, the sequence of elimination events, glycosidic bond cleavage and rearomatization of the estrogen A ring, was explored. Consistent with known experimental procedures, B3LYP calculations indicate that a proton source is needed to effect the Michael addition. Calculations also indicate that a catalytic mechanism, where one catechol estrogen quinone could adduct multiple purine bases, is unlikely. Experimental investigation toward an observed cationic reaction intermediate was also consistent with a stoichiometric reaction between estrone-3,4-quinone (E 1-3,4-Q) and dG. HPLC-MS analysis indicates that the cationic reaction intermediate contains the 2'-deoxyribose moiety. Assay of 4-OHE 1-1-N7Gua adduct formation and 2'-deoxyribose formation at different times during the reaction of E 1-3,4-Q with dG indicates that equimolar amounts of each are produced, further supporting a stoichiometric process with respect the catechol estrogen quinone. Differences in the UV spectroscopy of cationic reaction intermediate and the 4-OHE 1-1-N7Gua adduct allowed for kinetic analysis of the glycosidic bond cleavage process. Kinetic scanning analysis indicates that the decomposition of the cationic reaction intermediate is a first-order process with a t 1/2 of 40 min at 30 degrees C. Measurement of the unimolecular rate constant k at different temperatures afforded an Arrhenius plot, which provided values for Delta H, Delta S, and Delta G of 24.7 kcal/mol, 7.2 eu, and 26.8 kcal/mol, respectively. The computational data in conjunction with experimental results are consistent with a mechanism that involves a proton-assisted Michael addition to form an alpha-ketoenol ring system, followed by slow loss of the proton at C1 to restore the aromatic A ring, then fast cleavage of the glycosidic bond to form the 4-OHE 1-1-N7Gua adduct.
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Affiliation(s)
- Douglas E Stack
- Department of Chemistry, University of Nebraska at Omaha, 6001 Dodge Street, Omaha, Nebraska 68182-0109, USA.
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76
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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; 122:1949-57. [PMID: 18098283 DOI: 10.1002/ijc.23329] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Estrogens can become endogenous carcinogens via formation of catechol estrogen quinones, which react with DNA to form specific depurinating estrogen-DNA adducts. The mutations resulting from these adducts can lead to cell transformation and the initiation of breast cancer. Estrogen metabolites, conjugates and depurinating DNA adducts in urine samples from 46 healthy control women, 12 high-risk women and 17 women with breast cancer were analyzed. The estrogen metabolites, conjugates and depurinating DNA adducts were identified and quantified by using ultraperformance liquid chromatography/tandem mass spectrometry. The levels of the ratios of depurinating DNA adducts to their respective estrogen metabolites and conjugates were significantly higher in high-risk women (p < 0.001) and women with breast cancer (p < 0.001) than in control subjects. The high-risk and breast cancer groups were not significantly different (p = 0.62). After adjusting for patient characteristics, these ratios were still significantly associated with health status. Thus, the depurinating estrogen-DNA adducts are possible biomarkers for early detection of breast cancer risk and response to preventive treatment.
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Affiliation(s)
- Nilesh W Gaikwad
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-6805, USA
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77
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Venugopal D, Zahid M, Mailander PC, Meza JL, Rogan EG, Cavalieri EL, Chakravarti D. Reduction of estrogen-induced transformation of mouse mammary epithelial cells by N-acetylcysteine. J Steroid Biochem Mol Biol 2008; 109:22-30. [PMID: 18226522 PMCID: PMC2722841 DOI: 10.1016/j.jsbmb.2007.12.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A growing number of studies indicate that breast cancer initiation is related to abnormal estrogen oxidation to form an excess of estrogen-3,4-quinones, which react with DNA to form depurinating adducts and induce mutations. This mechanism is often called estrogen genotoxicity. 4-Catechol estrogens, precursors of the estrogen-3,4-quinones, were previously shown to account for most of the transforming and tumorigenic activity. We examined whether estrogen-induced transformation can be reduced by inhibiting the oxidation of a 4-catechol estrogen to its quinone. We demonstrate that E6 cells (a normal mouse epithelial cell line) can be transformed by a single treatment with a catechol estrogen or its quinone. The transforming activities of 4-hydroxyestradiol and estradiol-3,4-quinone were comparable. N-Acetylcysteine, a common antioxidant, inhibited the oxidation of 4-hydroxyestradiol to the quinone and consequent formation of DNA adducts. It also drastically reduced estrogen-induced transformation of E6 cells. These results strongly implicate estrogen genotoxicity in mammary cell transformation. Since N-acetylcysteine is well tolerated in clinical studies, it may be a promising candidate for breast cancer prevention.
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MESH Headings
- Acetylcysteine/pharmacology
- Animals
- Cell Line
- Cell Transformation, Neoplastic/chemically induced
- Cell Transformation, Neoplastic/drug effects
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Colony-Forming Units Assay
- DNA Adducts/drug effects
- DNA Adducts/metabolism
- Epithelial Cells/drug effects
- Epithelial Cells/metabolism
- Epithelial Cells/pathology
- Estradiol/analogs & derivatives
- Estradiol/toxicity
- Estrogens, Catechol/antagonists & inhibitors
- Estrogens, Catechol/toxicity
- Female
- Genes, ras
- Mammary Glands, Animal/drug effects
- Mammary Glands, Animal/metabolism
- Mammary Glands, Animal/pathology
- Mice
- Mutation
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Affiliation(s)
- Divya Venugopal
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805
| | - Muhammad Zahid
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805
| | - Paula C Mailander
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805
| | - Jane L. Meza
- Preventive and Societal Medicine, 984350 Nebraska Medical Center, Omaha, NE 68198-4350
| | - Eleanor G. Rogan
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805
| | - Ercole L. Cavalieri
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805
| | - Dhrubajyoti Chakravarti
- Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805
- Address correspondence to: Dr. D. Chakravarti, Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, Tel: (402) 559-2951, Fax: (402) 559-8068, E-mail:
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78
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Huang Y, Fernandez SV, Goodwin S, Russo PA, Russo IH, Sutter TR, Russo J. Epithelial to mesenchymal transition in human breast epithelial cells transformed by 17beta-estradiol. Cancer Res 2008; 67:11147-57. [PMID: 18056439 DOI: 10.1158/0008-5472.can-07-1371] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The estrogen dependence of breast cancer has long been recognized; however, the role of 17beta-estradiol (E(2)) in cancer initiation was not known until we showed that it induces complete neoplastic transformation of the human breast epithelial cells MCF-10F. E(2) treatment of MCF-10F cells progressively induced high colony efficiency and loss of ductulogenesis in early transformed (trMCF) cells and invasiveness in Matrigel invasion chambers. The cells that crossed the chamber membrane were collected and identified as bsMCF; their subclones were designated bcMCF; and the cells harvested from carcinoma formation in severe combined immunodeficient mice were designated caMCF. These phenotypes correlated with gene dysregulation during the progression of the transformation. The highest number of dysregulated genes was observed in caMCF, being slightly lower in bcMCF, and lowest in trMCF. This order was consistent with the extent of chromosome aberrations (caMCF > bcMCF >>> trMCF). Chromosomal amplifications were found in 1p36.12-pter, 5q21.1-qter, and 13q21.31-qter. Losses of the complete chromosome 4 and 8p11.21-23.1 were found only in tumorigenic cells. In tumor-derived cell lines, additional losses were found in 3p12.1-14.1, 9p22.1-pter, and 18q11.21-qter. Functional profiling of dysregulated genes revealed progressive changes in the integrin signaling pathway, inhibition of apoptosis, acquisition of tumorigenic cell surface markers, and epithelial-mesenchymal transition. In tumorigenic cells, the levels of E-cadherin, epithelial membrane antigen, and various keratins were low and CD44E/CD24 were negative, whereas SNAI2, vimentin, S100A4, FN1, HRAS, transforming growth factor beta1, and CD44H were high. The phenotypic and genomic changes triggered by estrogen exposure that lead normal cells to tumorigenesis confirm the role of this steroid hormone in cancer initiation.
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Affiliation(s)
- Yong Huang
- W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee, USA
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79
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Thapa P, Sherchan J, Karki R, Jeong TC, Lee ES. Depurination of dA and dG Induced by 2-bromopropane at the Physiological Condition. Biomol Ther (Seoul) 2007. [DOI: 10.4062/biomolther.2007.15.4.224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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80
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Bolton JL, Thatcher GRJ. Potential mechanisms of estrogen quinone carcinogenesis. Chem Res Toxicol 2007; 21:93-101. [PMID: 18052105 DOI: 10.1021/tx700191p] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
There is a clear association between the excessive exposure to estrogens and the development of cancer in hormone-sensitive tissues (breast, endometrium). It has become clear that there are likely multiple overlapping mechanisms of estrogen carcinogenesis. One major pathway is the extensively studied hormonal pathway, by which estrogen stimulates cell proliferation through nuclear estrogen receptor (ER)-mediated signaling, thus resulting in an increased risk of genomic mutations during DNA replication. A similar "nongenomic pathway", potentially involving newly discovered membrane-associated ERs, also appears to regulate extranuclear estrogen signaling pathways. This perspective is focused on a third pathway involving the metabolism of estrogens to catechols mediated by cytochrome P450 and further oxidation of these catechols to estrogen o-quinones. Oxidative enzymes, metal ions, and in some cases molecular oxygen can catalyze o-quinone formation, so that these electrophilic/redox-active quinones can cause damage within cells by alkylation and/or oxidation of cellular proteins and DNA in many tissues. It appears that the endogenous estrogen quinones primarily form unstable N3-adenine or N7-guanine DNA adducts, ultimately resulting in mutagenic apurinic sites. In contrast, equine estrogen quinones, formed from estrogens present in popular hormone replacement therapy prescriptions, generate a variety of DNA lesions, including bulky stable adducts, apurinic sites, DNA strand cleavage, and oxidation of DNA bases. DNA damage induced by these equine quinones is significantly increased in cells containing ERs, leading us to hypothesize a mechanism involving ER binding/alkylation by the catchol/quinone, resulting in a "Trojan horse". The "Trojan horse" carries the highly redox-active catechol to estrogen -sensitive genes, where high amounts of reactive oxygen species are generated, causing selective DNA damage. Our data further suggest that other key protein targets for estrogen o-quinones could be redox-sensitive enzymes (i.e, GST P1-1, QR). These proteins are involved in stress response cascades that are known to contribute to the regulation of cell proliferation and apoptosis. Finally, it has been shown that catechol estrogens can transform breast epithelial cells into a tumorigenic phenotype and that these transformed cells had differential gene expression of several genes involved in oxidative stress. Given the direct link between excessive exposure to estrogens, metabolism of estrogens, and increased risk of breast cancer, it is crucial that factors that affect the formation, reactivity, and cellular targets of estrogen quinoids be thoroughly explored.
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Affiliation(s)
- Judy L Bolton
- Department of Medicinal Chemisry and Pharmacognosy (M/C 781), College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612-7231, USA.
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81
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Zahid M, Saeed M, Lu F, Gaikwad N, Rogan E, Cavalieri E. Inhibition of catechol-O-methyltransferase increases estrogen-DNA adduct formation. Free Radic Biol Med 2007; 43:1534-40. [PMID: 17964424 PMCID: PMC2096412 DOI: 10.1016/j.freeradbiomed.2007.08.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 07/23/2007] [Accepted: 08/09/2007] [Indexed: 01/18/2023]
Abstract
The association found between breast cancer development and prolonged exposure to estrogens suggests that this hormone is of etiologic importance in the causation of the disease. Studies on estrogen metabolism, formation of DNA adducts, carcinogenicity, cell transformation, and mutagenicity have led to the hypothesis that reaction of certain estrogen metabolites, predominantly catechol estrogen-3,4-quinones, with DNA forms depurinating adducts [4-OHE1(E2)-1-N3Ade and 4-OHE(1)(E2)-1-N7Gua]. These adducts cause mutations leading to the initiation of breast cancer. Catechol-O-methyltransferase (COMT) is considered an important enzyme that protects cells from the genotoxicity and cytotoxicity of catechol estrogens, by preventing their conversion to quinones. The goal of the present study was to investigate the effect of COMT inhibition on the formation of depurinating estrogen-DNA adducts. Immortalized human breast epithelial MCF-10F cells were treated with 4-OHE2 (0.2 or 0.5 microM) for 24 h at 120, 168, 216, and 264 h postplating or one time at 1-30 microM 4-OHE2 with or without the presence of COMT inhibitor (Ro41-0960). The culture media were collected at each point, extracted by solid-phase extraction, and analyzed by HPLC connected with a multichannel electrochemical detector. The results demonstrate that MCF-10F cells oxidize 4-OHE2 to E1(E2)-3,4-Q, which react with DNA to form the depurinating N3Ade and N7Gua adducts. The COMT inhibitor Ro41-0960 blocked the methoxylation of catechol estrogens, with concomitant 3- to 4-fold increases in the levels of the depurinating adducts. Thus, low activity of COMT leads to higher levels of depurinating estrogen-DNA adducts that can induce mutations and initiate cancer.
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Affiliation(s)
| | | | | | | | | | - Ercole Cavalieri
- Corresponding author: Ercole L. Cavalieri, Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805. Phone: 402-559-7237; Fax: 402-559-8068. E-mail:
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82
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Zahid M, Gaikwad NW, Rogan EG, Cavalieri EL. Inhibition of depurinating estrogen-DNA adduct formation by natural compounds. Chem Res Toxicol 2007; 20:1947-53. [PMID: 18039013 DOI: 10.1021/tx700269s] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Specific metabolites of estrogens, catechol estrogen-3,4-quinones, if produced in relatively large amounts, can become chemical carcinogens by reacting with DNA to form predominantly depurinating DNA adducts. Estradiol (E2)-3,4-quinone (Q) reacts with DNA to form predominantly the depurinating DNA adducts, 4-hydroxyestradiol (OHE2)-1-N3Ade and 4-OHE 2-1-N7Gua. The depurinating adducts induce mutations by error-prone repair. We have conducted a study in which selected natural chemopreventing agents, N-acetylcysteine (NAcCys), melatonin, reduced lipoic acid, and resveratrol, have been tested for their ability to prevent the reaction of E(2)-3,4-Q with DNA. When DNA was incubated with E(2)-3,4-Q or lactoperoxidase-activated 4-OHE2 in the presence of an antioxidant, the formation of the N3Ade and N7Gua adducts was reduced. E(2)-3,4-Q or lactoperoxidase-oxidized 4-OHE 2 (87 microM final concentration) was incubated with calf-thymus DNA and one of the antioxidants at different ratios (1:0, 1:0.3, 1:1, and 1:3 with respect to E(2)-3,4-Q or 4-OHE2) at 37 degrees C. After 10 h, the DNA was precipitated, and the supernatant was analyzed by using ultraperformance liquid chromatography/tandem mass spectrometry (LC/MS/MS). As anticipated, resveratrol and melatonin did not affect the formation of the depurinating adducts when E(2)-3,4-Q was reacted with DNA in their presence. On the other hand, NAcCys and lipoic acid (reduced form) showed a significant inhibition of the formation of the depurinating adducts by E(2)-3,4-Q. With reaction of lactoperoxidase-activated 4-OHE2 with DNA, resveratrol achieved the highest level of inhibition, NAcCys and reduced lipoic acid produced moderate inhibition, and melatonin had the least inhibition. These results demonstrate that all four selected compounds can inhibit the formation of depurinating estrogen-DNA adducts and set the stage for studies of their ability to inhibit adduct formation and malignant transformation in mammary epithelial cells. This approach is highly useful for identifying agents to prevent the initiation of human cancers, especially breast and prostate cancer.
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Affiliation(s)
- Muhammad Zahid
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha 68198-6805, USA
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83
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Gaikwad NW, Rogan EG, Cavalieri EL. Evidence from ESI-MS for NQO1-catalyzed reduction of estrogen ortho-quinones. Free Radic Biol Med 2007; 43:1289-98. [PMID: 17893042 PMCID: PMC2064005 DOI: 10.1016/j.freeradbiomed.2007.07.021] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 06/13/2007] [Accepted: 07/16/2007] [Indexed: 12/14/2022]
Abstract
Estrogen ortho-quinones have been implicated as ultimate carcinogenic metabolites of estrogens. The present conclusion that estrogen ortho-quinones are not substrates for NAD(P)H:quinone oxidoreductase (NQO1) stems from earlier reports. In this investigation, we were successful in circumventing the problem of nonenzymatic reduction of estrogen quinone by NAD(P)H, which led to the above conclusion, and for the first time we show that NQO1 catalyzes the reduction of estrogen quinones. Mass spectrometric binding studies involving estradiol-3,4-quinone or menadione with NQO1 clearly support the formation of an enzyme-substrate physical complex. However, the NQO1 mass spectrum did not alter after addition of cholesterol, the control. Two different strategies were employed to ascertain the NQO1 activity in estrogen quinone reduction. First, the ping-pong mechanism of NQO1 catalysis was utilized to overcome the problem of nonenzymatic reduction of the substrate by NADH. Second, tetrahydrofolic acid, which has a lower reducing potential, was used as an alternate cofactor. Both of these methods confirmed the reduction of estradiol-3,4-quinone by NQO1, when the assay mixtures were analyzed by UV or liquid chromatography-mass spectrometry. Furthermore, reduction of 9,10-phenanthrene quinone or menadione was observed using the reported assay conditions. Thus, clear evidence for the catalytic reduction of estrogen ortho-quinones by NQO1 has been obtained; its mechanism and implications are discussed.
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Affiliation(s)
| | | | - Ercole L. Cavalieri
- Corresponding Author Ercole L. Cavalieri, Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-6805, Tel. 402-559-7237, Fax 402-559-8068, e-mail:
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84
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Salama SA, Jamaluddin M, Kumar R, Hassan MH, Al-Hendy A. Progesterone regulates catechol-O-methyl transferase gene expression in breast cancer cells: distinct effect of progesterone receptor isoforms. J Steroid Biochem Mol Biol 2007; 107:253-61. [PMID: 17689241 PMCID: PMC2254140 DOI: 10.1016/j.jsbmb.2007.03.049] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 03/22/2007] [Indexed: 11/18/2022]
Abstract
There is strong evidence that catechol-O-methyl transferase (COMT) protects breast cells against estrogen-induced cancer by detoxifying catecholestrogens, the carcinogenic estrogen metabolites. COMT gene expression is controlled by two promoters - a proximal promoter (COMTP1) and a distal promoter (COMTP2) - that regulate the expression of soluble (S-COMT) and membrane-bound (MB-COMT) isoforms, respectively. We investigated the transcriptional regulation of the COMT gene by progesterone/progesterone receptors in breast cancer cells. Our results indicated that progesterone (P4) downregulates COMT gene expression in breast cancer cell lines. In addition, the COMTP1 and COMTP2 harbor several progesterone response elements (PREs). Electrophoretic mobility shift assay (EMSA) indicated that nuclear extracts of T47D cells bind to the identified PREs in COMTP1. Site-directed mutagenesis of PREs in COMTP1 not only reversed the P4-induced inhibition of COMTP1, but also increased its basal activity. The two progesterone receptor isoforms, PR-A and PR-B, were found to have opposite effects on the regulation of P4 in COMT expression; PR-A is associated with P4-induced upregulation of COMT, while PR-B is associated with P4-induced downregulation of COMT. In summary, our data demonstrated that P4 downregulates the COMT gene expression through multiple PREs in the COMT promoters and that different progesterone receptor isoforms have distinctive effects on COMT gene expression.
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Affiliation(s)
- Salama A Salama
- Department of Obstetrics and Gynecology, 301 University Blvd., University of Texas Medical Branch, Galveston, TX 77555-1066, USA.
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85
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Chakravarti D, Venugopal D, Mailander PC, Meza JL, Higginbotham S, Cavalieri EL, Rogan EG. The role of polycyclic aromatic hydrocarbon-DNA adducts in inducing mutations in mouse skin. Mutat Res 2007; 649:161-78. [PMID: 17931959 DOI: 10.1016/j.mrgentox.2007.08.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 08/17/2007] [Accepted: 08/31/2007] [Indexed: 11/29/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAH) form stable and depurinating DNA adducts in mouse skin to induce preneoplastic mutations. Some mutations transform cells, which then clonally expand to establish tumors. Strong clues about the mutagenic mechanism can be obtained if the PAH-DNA adducts can be correlated with both preneoplastic and tumor mutations. To this end, we studied mutagenesis in PAH-treated early preneoplastic skin (1 day after exposure) and in the induced papillomas in SENCAR mice. Papillomas were studied by PCR amplification of the H-ras gene and sequencing. For benzo[a]pyrene (BP), BP-7,8-dihydrodiol (BPDHD), 7,12-dimethylbenz[a]anthracene (DMBA) and dibenzo[a,l]pyrene (DB[a,l]P), the codon 13 (GGC to GTC) and codon 61 (CAA to CTA) mutations in papillomas corresponded to the relative levels of Gua and Ade-depurinating adducts, despite BP and BPDHD forming significant amounts of stable DNA adducts. Such a relationship was expected for DMBA and DB[a,l]P, as they formed primarily depurinating adducts. These results suggest that depurinating adducts play a major role in forming the tumorigenic mutations. To validate this correlation, preneoplastic skin mutations were studied by cloning H-ras PCR products and sequencing individual clones. DMBA- and DB[a,l]P-treated skin showed primarily A.T to G.C mutations, which correlated with the high ratio of the Ade/Gua-depurinating adducts. Incubation of skin DNA with T.G-DNA glycosylase eliminated most of these A.T to G.C mutations, indicating that they existed as G.T heteroduplexes, as would be expected if they were formed by errors in the repair of abasic sites generated by the depurinating adducts. BP and its metabolites induced mainly G.C to T.A mutations in preneoplastic skin. However, PCR over unrepaired anti-BPDE-N(2)dG adducts can generate similar mutations as artifacts of the study protocol, making it difficult to establish an adduct-mutation correlation for determining which BP-DNA adducts induce the early preneoplastic mutations. In conclusion, this study suggests that depurinating adducts play a major role in PAH mutagenesis.
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86
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Raoof JB, Kiani A, Ojani R, Khalilzadeh MA. Anodic Oxidation of Catechols in the Presence of 1,3-Indandione. A Green Electrosynthetic Approach to New Catechol Derivatives. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2007. [DOI: 10.1246/bcsj.80.1573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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87
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Abstract
Estrogen ortho-quinones have been implicated as ultimate carcinogenic metabolites of estrogens. The present conclusion that estrogen ortho-quinones are not substrates for NAD(P)H:quinone oxidoreductase (NQO1) stems from earlier reports. In this investigation, we were successful in circumventing the problem of nonenzymatic reduction of estrogen quinone by NAD(P)H, which led to the above conclusion, and for the first time we show that NQO1 catalyzes the reduction of estrogen quinones. Mass spectrometric binding studies involving estradiol-3,4-quinone or menadione with NQO1 clearly support the formation of an enzyme-substrate physical complex. However, the NQO1 mass spectrum did not alter after addition of cholesterol, the control. Two different strategies were employed to ascertain the NQO1 activity in estrogen quinone reduction. First, the ping-pong mechanism of NQO1 catalysis was utilized to overcome the problem of nonenzymatic reduction of the substrate by NADH. Second, tetrahydrofolic acid, which has a lower reducing potential, was used as an alternate cofactor. Both of these methods confirmed the reduction of estradiol-3,4-quinone by NQO1, when the assay mixtures were analyzed by UV or liquid chromatography-mass spectrometry. Furthermore, reduction of 9,10-phenanthrene quinone or menadione was observed using the reported assay conditions. Thus, clear evidence for the catalytic reduction of estrogen ortho-quinones by NQO1 has been obtained; its mechanism and implications are discussed.
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88
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Zhang Y, Gaikwad NW, Olson K, Zahid M, Cavalieri EL, Rogan EG. Cytochrome P450 isoforms catalyze formation of catechol estrogen quinones that react with DNA. Metabolism 2007; 56:887-94. [PMID: 17570247 DOI: 10.1016/j.metabol.2007.03.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Accumulating evidence suggests that specific metabolites of estrogens, namely, catechol estrogen quinones, react with DNA to form adducts and generate apurinic sites, which can lead to the mutations that induce breast cancer. Oxidation of estradiol (E(2)) produces 2 catechol estrogens, 4-hydroxyestradiol (4-OHE(2)) and 2-OHE(2) among the major metabolites. These, in turn, are oxidized to the quinones, E(2)-3,4-quinone (E(2)-3,4-Q) and E(2)-2,3-Q, which can react with DNA. Oxidation of E(2) to 2-OHE(2) is mainly catalyzed by cytochrome P450 (CYP) 1A1, and CYP3A4, whereas oxidation of E(2) to 4-OHE(2) in extrahepatic tissues is mainly catalyzed by CYP1B1 as well as some CYP3As. The potential involvement of CYP isoforms in the further oxidation of catechols to semiquinones and quinones has, however, not been investigated in detail. In this project, to identify the potential function of various CYPs in oxidizing catechol estrogens to quinones, we used different recombinant human CYP isoforms, namely, CYP1A1, CYP1B1, and CYP3A4, with the scope of oxidizing the catechol estrogens 2-OHE(2) and 4-OHE(2) to their respective estrogen quinones, which then reacted with DNA. The depurinating adducts 2-OHE(2)-6-N3Ade, 4-OHE(2)-1-N3Ade, and 4-OHE(2)-1-N7Gua were observed in the respective reaction systems by ultraperformance liquid chromatography/tandem mass spectrometry. Furthermore, more than 100-fold higher levels of estrogen-glutathione (GSH) conjugates were detected in the reactions. Glutathione conjugates were observed, in much smaller amounts, when control microsomes were used. Depurinating adducts, as well as GSH conjugates, were obtained when E(2)-3,4-Q was incubated with CYP1B1 or control microsomes in a 30-minute reaction, further demonstrating that GSH is present in these recombinant enzyme preparations. These experiments demonstrated that CYP1A1, CYP1B1, and CYP3A4 are able to oxidize catechol estrogens to their respective quinones, which can further react with GSH, protein, and DNA, the last resulting in depurinating adducts that can lead to mutagenesis.
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Affiliation(s)
- Yan Zhang
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
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89
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Tanaka Y, Hirata H, Chen Z, Kikuno N, Kawamoto K, Majid S, Tokizane T, Urakami S, Shiina H, Nakajima K, Dhir R, Dahiya R. Polymorphisms of catechol-O-methyltransferase in men with renal cell cancer. Cancer Epidemiol Biomarkers Prev 2007; 16:92-7. [PMID: 17220335 DOI: 10.1158/1055-9965.epi-06-0605] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The estrogen metabolite, 4-hydroxy-estrogen, has been shown to play a role in malignant transformation of male kidneys. To counteract the effects of this catechol-estrogen, the catechol-O-methyltransferase (COMT) enzyme is capable of neutralizing the genotoxic effects of this compound. A polymorphic variant of COMT has been shown to have a reduced enzyme activity, and thus, we hypothesize that single nucleotide polymorphisms of the COMT gene can be a risk factor for renal cell cancer (RCC). To determine this hypothesis, a study of a Japanese male population was used and the genetic distributions of COMT polymorphisms at codons 62 (C-->T), 72 (G-->T), and 158 (G-->A) were analyzed in 157 normal healthy subjects and 123 sporadic RCC (clear cell type) samples by using a sequence-specific PCR technique. These experiments show that the variant genotype (P = 0.025) and allele (P = 0.011) at codon 62 is a risk factor for RCC. The odds ratio and 95% confidence interval for cancer were 3.16 and 1.29 to 7.73, respectively, for the T/T genotype as compared with wild-type. No associations for renal cancer were found at either codons 72 or 158 in this Japanese male population. However, codons 62 and 158 were observed to be in linkage disequilibrium, and haplotype analysis shows the combined forms of T-A, T-G, and C-A to be associated with RCC as compared with C-G (P < 0.001). When evaluating the risk of COMT polymorphisms with grade of cancer, no associations were observed for any of the genotypes. This study is the first to report COMT polymorphism to be associated with RCC. These results are important in understanding the role of COMT polymorphisms in the pathogenesis of RCC.
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Affiliation(s)
- Yuichiro Tanaka
- Department of Urology, Veterans Affairs Medical Center and University of California at San Francisco, 4150 Clement Street, San Francisco, CA 94121, USA
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90
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Roy D, Cai Q, Felty Q, Narayan S. Estrogen-induced generation of reactive oxygen and nitrogen species, gene damage, and estrogen-dependent cancers. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2007; 10:235-57. [PMID: 17620201 DOI: 10.1080/15287390600974924] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In addition to the direct effect of estrogen on mitochondria and the redox cycling of catechol estrogen, estrogen-induced proinflammatory cytokines, such as interleukin-1 beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha), also generate reactive oxygen and nitrogen species (RO/NS). Different cellular signaling pathways may operate in response to varying levels of estrogen-induced RO/NS, leading to genotoxic damage, cell apoptosis, or cell growth. At high levels of RO/NS, cells receiving genotoxic insults, if not repaired, may engage the apoptotic pathways. There is increasing evidence supporting that estrogen-induced alterations in the genome of cells is produced by oxidative attack. Furthermore, ROS generated by estrogen exposure and/or active metabolites of estrogen in combination with receptor-mediated proliferation of genetically damaged cells may be involved in tumor development. This view is supported by the findings of DNA modifications produced in vitro or in vivo by natural and synthetic estrogens in the target organs of cancer both in experimental models and in humans. Interaction of estrogen-induced oxidants and estrogen metabolites with DNA was shown to generate mutations in genes. Cotreatment with an inhibitor of IL-1beta and TNF-alpha synthesis, pentoxifylline, decreased stilbene estrogen-induced levels of myeloperoxidase (MPO), 8-hydroxydeoxyguanosine formation, and gene mutations, and prevented stilbene estrogen-induced lesions. Stable MCF-7 clones overexpressing IL-1beta resulted in a high level of IL-1beta peptide secretion undergoing cell apoptosis, and an elevated level of p53 protein in response to high oxidative stress when compared to nontransfected cells, whereas MCF-7 clones overexpressing IL-1beta that resulted in a moderate level of IL-1beta secretion stimulated the clonal expansion of MCF-7 and TM3 cells. Estrogen-induced MCF-7 cell growth and cyclin D1 expression were suppressed by antioxidants and mitochondrial blockers. These studies support that in addition to ovarian estrogen-mediated ER signaling, mitogenic signals may also come from estrogen-induced RO/NS. Further validation of this concept that the concentration of the RO/NS within the cellular microenvironment determines its stimulatory or inhibitory growth signals as well as its genotoxic effects regulating the growth of estrogen-dependent tumors may result in novel preventive strategies.
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Affiliation(s)
- Deodutta Roy
- Department of Environmental and Occupational Health, Florida International University, Miami, Florida 33199, USA.
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91
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Lu F, Zahid M, Saeed M, Cavalieri EL, Rogan EG. 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. J Steroid Biochem Mol Biol 2007; 105:150-8. [PMID: 17582757 PMCID: PMC1986824 DOI: 10.1016/j.jsbmb.2006.12.102] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Accepted: 12/21/2006] [Indexed: 11/24/2022]
Abstract
Formation of estrogen metabolites that react with DNA is thought to be a mechanism of cancer initiation by estrogens. The estrogens estrone (E(1)) and estradiol (E(2)) can form catechol estrogen (CE) metabolites, catechol estrogen quinones [E(1)(E(2))-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-OHE(1)(E(2))-1-N3Ade and 4-OHE(1)(E(2))-1-N7Gua adducts in human breast epithelial cells. MCF-10F cells were treated with TCDD, a cytochrome P450 inducer, then with E(2) 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 E(2) metabolism to 4-OHE(1)(E(2)) and 4-OCH(3)E(1)(E(2)). Inclusion of Ro41-0960 and E(2) 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 microM E(2), whereas without the inhibitor, no increases in adducts were detected with E(2) < or =10 microM. We conclude that low COMT activity and increased formation of depurinating adducts can be critical factors leading to initiation of breast cancer.
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Affiliation(s)
- Fang Lu
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
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92
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Rivera-Portalatin NM, Vera-Serrano JL, Prokai-Tatrai K, Prokai L. Comparison of estrogen-derived ortho-quinone and para-quinol concerning induction of oxidative stress. J Steroid Biochem Mol Biol 2007; 105:71-5. [PMID: 17582759 PMCID: PMC2752863 DOI: 10.1016/j.jsbmb.2006.11.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Accepted: 11/13/2006] [Indexed: 01/13/2023]
Abstract
Ortho-quinones formed from catechol estrogens are considered prooxidants due to the production of superoxide radical anions through redox cycling via semiquinones. Para-quinols have been identified as novel metabolites of and as the major products of hydroxyl-radical scavenging by estrogens. Cycling of these compounds has also been discovered, because they are converted back to the parent estrogen via reductive aromatization in vitro and in vivo. We hypothesized that, unlike ortho-quinones, para-quinols do not induce oxidative stress due to this cycling. Like the estrogen itself, the 17beta-estradiol-derived para-quinol (10beta,17beta-dihydroxyestra-1,4-diene-3-one) did not induce oxidative stress, as the rate of hydrogen peroxide production during the incubations of the compounds in various tissue homogenates was not significantly different from that of the control experiments performed without the addition of a test compound. We also confirmed that the estrogen metabolite estra-1,5(10)-dien-3,4,17-trione (estrone 3,4-quinone) was a profound prooxidant due to redox cycling, especially in uterine tissue. Therefore, we concluded that para-quinols do not induce oxidative stress.
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Affiliation(s)
- Nilka M. Rivera-Portalatin
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610-0485, USA
| | - José L. Vera-Serrano
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Katalin Prokai-Tatrai
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Laszlo Prokai
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610-0485, USA
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- Corresponding author. Tel.: +1 817 7352206; fax: +1 817 7352651. (L. Prokai)
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93
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Abstract
The World Health Organization (WHO) classified oestrogens as carcinogenic in humans. One of the main arguments has been that oestrogens not only can promote cancers but also may initiate mutations caused by certain oestrogen metabolites. Indeed there is evidence that they can have biological properties even at very low concentrations which can exceed manifold those of their parent substance. Highly sophisticated laboratory methods will allow us to understand oestrogenic effects as a net effect of the corresponding metabolite pattern. Current research focuses on the possible carcinogenic properties of 4-hydroxyoestrogens and 16-alpha-hydroxyoestrone, but also on the anticancerogenic effects particularly of 2-methoxyoestradiol. Thus, potential toxic secondary metabolites like 4-quinones can be eliminated, e.g. by methylation. 2-methoxyoestradiol is a potent antiproliferative and antiangiogenic metabolite, and is currently tested in patients with refractory metastatic breast cancer. Observational trials have demonstrated that the ratio of 2- to 16-alpha-hydroxyoestrone is decreased in women with breast cancer. We have been able to demonstrate that oestradiol metabolism during HRT can be influenced by administration route, possibly also by certain progestogens. In in vitro and animal experiments certain oestrogen metabolites indeed can act as carcinogens. However, since for the formation of these metabolites the appearance of very special conditions is a prerequisite and also various protective mechanisms are present, this might only contribute to breast carcinogenesis in very rare cases. However, the clinical relevance remains unclear and it appears to be important to ascertain this issue.
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Affiliation(s)
- Alfred O Mueck
- University Women's Hospital of Tuebingen, Tuebingen, Germany
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94
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Matyjasik J, Cybulski C, Masojć B, Jakubowska A, Serrano-Fernandez P, Górski B, Debniak T, Huzarski T, Byrski T, Gronwald J, Złowocka E, Narod SA, Scott R, Lubinski J. CYP1B1 and predisposition to breast cancer in Poland. Breast Cancer Res Treat 2007; 106:383-8. [PMID: 17458695 DOI: 10.1007/s10549-007-9500-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Accepted: 01/01/2007] [Indexed: 11/26/2022]
Abstract
BACKGROUND The CYP1B1 gene is a polymorphic member of the P450 gene family and is considered to be a candidate gene for cancers of various types. OBJECTIVE We inquired whether four SNPs in the CYP1B1 gene, alone or in combination, might be associated with breast cancer risk in Poland. METHODS We genotyped 2017 cases of breast cancer and 876 controls, for four SNPs in the CYP1B1 gene. Genotype and haplotype frequencies were compared in cases and controls. RESULTS In combinations of the R48G, A119S and L432V SNPs, four of the eight CYP1B1 haplotypes were more common in controls than in cases and each of these appeared to have a significant protective effect. A large reduction in risk was observed for women who were homozygous for one of these four haplotypes (OR = 0.2; 95%; CI = 0.05-0.5; P = 0.001) compared to women who were homozygous for the most common haplotype. In contrast, women who were homozygous for the GTC haplotype were at increased risk (OR = 1.5; 95%; CI = 1.0-2.1; P = 0.03) compared to women with the most common haplotype. CONCLUSIONS The CYP1B1 gene appears to influence breast cancer susceptibility in Poland.
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Affiliation(s)
- Joanna Matyjasik
- Department of Genetics and Pathology, International Hereditary Cancer Center, Pomeranian Medical University, Szczecin, Poland
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95
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Saeed M, Rogan E, Fernandez SV, Sheriff F, Russo J, Cavalieri E. Formation of depurinating N3Adenine and N7Guanine adducts by MCF-10F cells cultured in the presence of 4-hydroxyestradiol. Int J Cancer 2007; 120:1821-4. [PMID: 17230531 DOI: 10.1002/ijc.22399] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Metabolic conversion of endogenous estrogens, estradiol (E2) and estrone (E1), to the catechol estrogens 4-hydroxyE1(E2) [4-OHE1(E2)] has been implicated in the initiation of cancer in rodents and humans. Evidence collected in our laboratories has shown that 4-OHE1(E2) are enzymatically oxidized to E1(E2)-3,4-quinones [E1(E2)-3,4-Q], which have the potential to damage DNA by forming predominantly depurinating adducts, 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua, leading to the accumulation of mutations and probably cell transformation. The human breast epithelial cell line MCF-10F has been transformed by treatment with E2 or 4-OHE2. We have used MCF-10F cells to study the presence of adducts and conjugates after treatment with 4-OHE2. To mimic the intermittent exposure of breast cells to endogenous estrogens, MCF-10F cells were treated with 1 microM 4-OHE2 for a 24-h period at 72, 120, 192 and 240 h postplating. Culture media were collected at each point, extracted by solid-phase extraction and analyzed by HPLC connected with a multichannel electrochemical detector and/or ultraperformance liquid chromatography/tandem mass spectrometry. Media from successive treatments with 4-OHE2 showed the formation of methoxy and cysteine conjugates, and the depurinating adducts 4-OHE1(E2)-1-N3Ade. The amount of 4-OHE1(E2)-1-N3Ade adducts was higher after the third treatment; smaller amounts of the 4-OHE1(E2)-1-N7Gua adducts were detected after the second and third treatments. These results demonstrate that MCF-10F cells oxidize 4-OHE2 to E1(E2)-3,4-Q, which react with DNA to form the depurinating N3Ade and N7Gua adducts. This DNA damage can play an important role in the 4-OHE2-induced mutations and transformation of MCF-10F cells to malignant cells.
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Affiliation(s)
- Muhammad Saeed
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE, USA
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96
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Mello MLS, Vidal BC, Russo IH, Lareef MH, Russo J. DNA content and chromatin texture of human breast epithelial cells transformed with 17-beta-estradiol and the estrogen antagonist ICI 182,780 as assessed by image analysis. Mutat Res 2007; 617:1-7. [PMID: 17270221 PMCID: PMC2614559 DOI: 10.1016/j.mrfmmm.2006.08.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Revised: 07/24/2006] [Accepted: 08/24/2006] [Indexed: 10/23/2022]
Abstract
The immortalized human breast epithelial MCF-10F cell line, although estrogen receptor alpha negative, develops cell proliferating activities and invasiveness indicative of neoplastic transformation, after treatment with 17-beta-estradiol (E-2). These effects are similar to those produced by benzo[a]pyrene (BP). Since we have previously reported changes in the nuclear parameters accompanying BP-induced tumorigenesis in MCF-10F cells, we have examined whether similar alterations occur in E-2-treated cells. We therefore studied DNA amounts and other nuclear parameters in Feulgen-stained MCF-10F cells after treatment with various concentrations of E-2, BP, the estrogen antagonist ICI 182,780, and E-2 in the presence of ICI 182,780. E-2 caused a certain loss of DNA and changes in the nuclear size and chromatin supraorganization of MCF-10F cells. Many of these changes were similar to those produced by BP and were indicative of neoplastic transformation. More intense chromatin remodelling was seen with 70 nM E-2. Since these changes were not abrogated totally or partially by ICI 182,780, the neoplastic transformation of MCF-10F cells stimulated by E-2 involved a process that was independent of estrogen alpha-receptors. The changes produced by ICI 182,780 alone were attributed to effects other than its well-known anti-estrogenic activity.
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Affiliation(s)
- Maria Luiza S Mello
- Department of Cell Biology, Institute of Biology, UNICAMP, 13083-863 Campinas, SP, Brazil.
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97
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Saeed M, Higginbotham S, Rogan E, Cavalieri E. Formation of depurinating N3adenine and N7guanine adducts after reaction of 1,2-naphthoquinone or enzyme-activated 1,2-dihydroxynaphthalene with DNA. Implications for the mechanism of tumor initiation by naphthalene. Chem Biol Interact 2006; 165:175-88. [PMID: 17224140 DOI: 10.1016/j.cbi.2006.12.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 12/04/2006] [Accepted: 12/05/2006] [Indexed: 11/29/2022]
Abstract
Naphthalene is considered by the US Environmental Protection Agency to be a carcinogenic compound based on inhalation studies in rats. The primary metabolite of naphthalene is naphthalene 1,2-arene oxide. This unstable intermediate can lead to formation of 1-naphthol and naphthalene-1,2-dihydrodiol. Secondary metabolites include 1,2-dihydroxynaphthalene (1,2-DHN), which can be further oxidized to 1,2-naphthoquinone (1,2-NQ). Based on the metabolism of naphthalene and its similarity to the metabolic activation of carcinogenic natural estrogens, synthetic estrogens and benzene, we hypothesize that naphthalene is activated to initiate cancer by reaction of 1,2-NQ with DNA to form the depurinating adducts 1,2-DHN-4-N3Ade and 1,2-DHN-4-N7Gua. These adducts were synthesized by reaction of 1,2-NQ with Ade or dG in acetic acid/water/DMF (1:1:1). 1,2-NQ was reacted with DNA, and the depurinating 1,2-DHN-4-N3Ade and 1,2-DHN-4-N7Gua adducts were analyzed by ultraperformance liquid chromatography/tandem mass spectrometry and HPLC with electrochemical detection. After the reaction of 1,2-NQ with DNA, the N3Ade and N7Gua adducts were found. Similarly, when 1,2-DHN was activated by tyrosinase in the presence of DNA, higher amounts of the N3Ade and N7Gua adducts were detected. These same adducts were also formed when 1,2-DHN was activated by prostaglandin H synthase or 3-methylcholanthrene-induced rat liver microsomes in the presence of DNA. These depurinating adducts are analogous to those obtained from the ortho-quinones of natural estrogens, synthetic estrogens and benzene. These results suggest that reaction of ortho-quinones with DNA by 1,4-Michael addition is a general mechanism of weak carcinogenesis that occurs with naphthalene and a number of other aromatic compounds.
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Affiliation(s)
- Muhammad Saeed
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA
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98
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Abstract
Estrogens are considered to play a major role in promoting the proliferation of both the normal and the neoplastic breast epithelium. Their role as breast carcinogens has long been suspected and recently confirmed by epidemiological studies. Three major mechanisms are postulated to be involved in their carcinogenic effects: stimulation of cellular proliferation through their receptor-mediated hormonal activity, direct genotoxic effects by increasing mutation rates through a cytochrome P450-mediated metabolic activation, and induction of aneuploidy. Recently it has been fully demonstrated that estrogens are carcinogenic in the human breast by testing in an experimental system the natural estrogen 17beta-estradiol (E(2)) by itself or its metabolites 2-hydroxy, 4-hydroxy, and 16-a-hydroxy-estradiol (2-OH-E(2), 4-OH-E(2), and 16-alpha-OH E(2)), respectively, by inducing neoplastic transformation of human breast epithelial cells (HBEC) MCF-10F in vitro to a degree at least similar to that induced by the chemical carcinogen benz(a)pyrene (BP). Neither Tamoxyfen (TAM) nor ICI-182,780 abrogated the transforming efficiency of estrogen or its metabolites. The E(2) induced expression of anchorage independent growth, loss of ductulogenesis in collagen, invasiveness in Matrigel, is associated with the loss of 9p11-13 and only invasive cells that exhibited a 4p15.3-16 deletion were tumorigenic. Tumors were poorly differentiated ER-alpha and progesterone receptor negative adenocarcinomas that expressed keratins, EMA and E-cadherin. The E(2) induced tumors and tumor-derived cell lines exhibited loss of chromosome 4, deletions in chromosomes 3p12.3-13, 8p11.1-21, 9p21-qter, and 18q, and gains in 1p, and 5q15-qter. The induction of complete transformation of the human breast epithelial cell MCF-10F in vitro confirms the carcinogenicity of E(2), supporting the concept that this hormone could act as an initiator of breast cancer in women. This model provides a unique system for understanding the genomic changes that intervene for leading normal cells to tumorigenesis and for testing the functional role of specific genomic events taking place during neoplastic transformation.
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Affiliation(s)
- J Russo
- Breast Cancer Research Laboratory, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA.
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99
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Crooke PS, Ritchie MD, Hachey DL, Dawling S, Roodi N, Parl FF. Estrogens, enzyme variants, and breast cancer: a risk model. Cancer Epidemiol Biomarkers Prev 2006; 15:1620-9. [PMID: 16985022 DOI: 10.1158/1055-9965.epi-06-0198] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Oxidative metabolites of estrogens have been implicated in the development of breast cancer, yet relatively little is known about the metabolism of estrogens in the normal breast. We developed a mathematical model of mammary estrogen metabolism based on the conversion of 17beta-estradiol (E(2)) by the enzymes cytochrome P450 (CYP) 1A1 and CYP1B1, catechol-O-methyltransferase (COMT), and glutathione S-transferase P1 into eight metabolites [i.e., two catechol estrogens, 2-hydroxyestradiol (2-OHE(2)) and 4-hydroxyestradiol (4-OHE(2)); three methoxyestrogens, 2-methoxyestradiol, 2-hydroxy-3-methoxyestradiol, and 4-methoxyestradiol; and three glutathione (SG)-estrogen conjugates, 2-OHE(2)-1-SG, 2-OHE(2)-4-SG, and 4-OHE(2)-2-SG]. When used with experimentally determined rate constants with purified enzymes, the model provides for a kinetic analysis of the entire metabolic pathway. The predicted concentration of each metabolite during a 30-minute reaction agreed well with the experimentally derived results. The model also enables simulation for the transient quinones, E(2)-2,3-quinone (E(2)-2,3-Q) and E(2)-3,4-quinone (E(2)-3,4-Q), which are not amenable to direct quantitation. Using experimentally derived rate constants for genetic variants of CYP1A1, CYP1B1, and COMT, we used the model to simulate the kinetic effect of enzyme polymorphisms on the pathway and identified those haplotypes generating the largest amounts of catechols and quinones. Application of the model to a breast cancer case-control population identified a subset of women with an increased risk of breast cancer based on their enzyme haplotypes and consequent E(2)-3,4-Q production. This in silico model integrates both kinetic and genomic data to yield a comprehensive view of estrogen metabolomics in the breast. The model offers the opportunity to combine metabolic, genetic, and lifetime exposure data in assessing estrogens as a breast cancer risk factor.
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Affiliation(s)
- Philip S Crooke
- Department of Pathology, TVC 4918, Vanderbilt University, Nashville, TN 37232, USA
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100
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Cavalieri E, Rogan E. Catechol Quinones of Estrogens in the Initiation of Breast, Prostate, and Other Human Cancers: Keynote Lecture. Ann N Y Acad Sci 2006; 1089:286-301. [PMID: 17261777 DOI: 10.1196/annals.1386.042] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Estrogens can be converted to electrophilic metabolites, particularly the catechol estrogen-3,4-quinones, estrone(estradiol)-3,4-quinone [E(1)(E(2))-3,4-Q], which react with DNA to form depurinating adducts. These adducts are released from DNA to generate apurinic sites. Error-prone repair of this damage leads to the mutations that initiate breast, prostate, and other types of cancer. The reaction of E(1)(E(2))-3,4-Q with DNA forms the depurinating adducts 4-hydroxyE(1)(E(2))-1-N3adenine [4-OHE(1)(E(2))-1-N3Ade] and 4-OHE(1)(E(2))-1-N7guanine(Gua). These two adducts constitute >99% of the total DNA adducts formed. The E(1)(E(2))-2,3-Q forms small amounts of the depurinating 2-OHE(1)(E(2))-6-N3Ade adducts. Reaction of the quinones with DNA occurs more abundantly when estrogen metabolism is unbalanced. Such an imbalance is the result of overexpression of estrogen-activating enzymes and/or deficient expression of deactivating (protective) enzymes. Excessive formation of E(1)(E(2))-3,4-Q is the result of this imbalance. Oxidation of catechols to semiquinones and quinones is a mechanism of tumor initiation not only for endogenous estrogens, but also for synthetic estrogens such as hexestrol and diethylstilbestrol, a human carcinogen. This mechanism is also involved in the initiation of leukemia by benzene, rat olfactory tumors by naphthalene, and neurodegenerative diseases such as Parkinson's disease by dopamine. In fact, dopamine quinone reacts with DNA similarly to the E(1)(E(2))-3,4-Q, forming analogous depurinating N3Ade and N7Gua adducts. The depurinating adducts that migrate from cells and can be found in body fluids can also serve as biomarkers of cancer risk. In fact, a higher level of estrogen-DNA adducts has been found in the urine of men with prostate cancer and in women with breast cancer compared to healthy controls. This unifying mechanism of the origin of cancer and other diseases suggests preventive strategies based on the level of depurinating DNA adducts that generate the first critical step in the initiation of diseases.
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Affiliation(s)
- Ercole Cavalieri
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 8198-6805, USA.
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