Estrogens are known in induce tumors in laboratory animals. In humans, the administration of estrogens has been associated with a high incidence of endometrial carcinoma and, more recently, of breast cancer. In this project, we propose to synthesize and test several estrogens modified in a way to be hormonally highly potent yet completely noncarcinogenic. In our work during the past funding period, we demonstrated that hormonal potency of estrogens and carcinogenic activity are not inherently associated with each other but are separable properties of substances. It is expected that steroid estrogens which can not form any catechol metabolites, will lack carcinogenic activity. Such substances are needed to prove that catechol estrogens are the carcinogenic metabolites of estrogens and to provide 'safe' estrogen medication for human use. Specifically, we will synthesize 11beta-methoxy-4-fluoroestradiol, 11beta-methyl-4-fluoroestradiol, and 2- fluoro-6-methylestradiol and test these estrogens in vitro and in vivo for their estrogenic activity, toxicity and effect on metabolizing enzymes. The toxicity in vitro will be assessed by 1. measuring catechol formation by hamster liver and kidney microsomes using a product isolation assay, 2. determining the methylation of catechol metabolites synthesized from modified estrogens, 3. examining the influence of chronic administration of modified estrogens on hamster liver and kidney estrogen 2- and/or 4- hydroxylases, 4. measuring microsome-mediated DNA adduct formation in vitro using 32P-postlabeling analysis, 5. measuring microsome-mediated protein damage by a newly developed NaB3H4 reduction assay. In vivo the estrogenic potency and lack of carcinogenic activity will be tested in Syrian hamsters and in mice. Tissues from these animals will also be investigated for DNA adduct formation and protein damage, and concentrations of estrogen and catechol estrogen (if formed).

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA043232-07
Application #
3185356
Study Section
Metabolic Pathology Study Section (MEP)
Project Start
1986-02-01
Project End
1994-06-30
Budget Start
1992-07-17
Budget End
1993-06-30
Support Year
7
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Type
Schools of Medicine
DUNS #
041367053
City
Galveston
State
TX
Country
United States
Zip Code
77555
Zhu, B T; Evaristus, E N; Antoniak, S K et al. (1996) Metabolic deglucuronidation and demethylation of estrogen conjugates as a source of parent estrogens and catecholestrogen metabolites in Syrian hamster kidney, a target organ of estrogen-induced tumorigenesis. Toxicol Appl Pharmacol 136:186-93
Zhu, B T; Liehr, J G (1994) Quercetin increases the severity of estradiol-induced tumorigenesis in hamster kidney. Toxicol Appl Pharmacol 125:149-58
Zhu, B T; Roy, D; Liehr, J G (1993) The carcinogenic activity of ethinyl estrogens is determined by both their hormonal characteristics and their conversion to catechol metabolites. Endocrinology 132:577-83
Han, X L; Liehr, J G (1992) Induction of covalent DNA adducts in rodents by tamoxifen. Cancer Res 52:1360-3
Weisz, J; Bui, Q D; Roy, D et al. (1992) Elevated 4-hydroxylation of estradiol by hamster kidney microsomes: a potential pathway of metabolic activation of estrogens. Endocrinology 131:655-61
Liehr, J G; Folse, D S; Roy, D (1992) Lack of effectiveness of antiestrogens RU 39,411 or keoxifene in the prevention of estrogen-induced tumors in Syrian hamsters. Cancer Lett 64:23-9
Roy, D; Liehr, J G (1992) Target organ-specific inactivation of drug metabolizing enzymes in kidney of hamsters treated with estradiol. Mol Cell Biochem 110:31-9
Liehr, J G; Gladek, A; Macatee, T et al. (1991) DNA adduct formation in liver and kidney of male Syrian hamsters treated with estrogen and/or alpha-naphthoflavone. Carcinogenesis 12:385-9
Roy, D; Hachey, D L; Liehr, J G (1991) Determination of estradiol 2- and 4-hydroxylase activities by gas chromatography with electron-capture detection. J Chromatogr 567:309-18
Roy, D; Weisz, J; Liehr, J G (1990) The O-methylation of 4-hydroxyestradiol is inhibited by 2-hydroxyestradiol: implications for estrogen-induced carcinogenesis. Carcinogenesis 11:459-62

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