Initial studies have shown that the structure of the estrogen ligand can dictate the range of genes induced and the concentration limits for the ligand to stimulate an estrogen response in MCF-7 human breast cancer cells. Structural modifications to the 17beta-estradiol (E2) molecule in the A and D rings are influential in discriminating among the range of estrogen responsive genes. The proposed studies are designed to first evaluate the effects of these E2 derivatives on induction of four E2-responsive genes (pS2, progesterone receptor, tissue plasminogen activator, and cathepsin D) and MCF-7 cell growth. Further """"""""mapping"""""""" of the estrogen molecule for other components which may be important in the induction of responsive genes will be carried out with a series of B-and C-ring based derivatives of E2. Studies of the aberrant ER complex formed with E2 analogues will be pursued by documenting structural alterations in the analogue-receptor complex in solution by sucrose density gradient analysis and when bound to the estrogen responsive element (ERE) by gel retardation analysis. It is hypothesized that ER complexed with structurally altered estrogens may bind with different affinities and/or conformations to the consensus ERE and functional EREs that vary from it by one or more nucleotides. Furthermore, the possibility that analogue-ER complexes may be interacting with other regulatory elements known to influence estrogen responsive gene expression will be considered. Investigations concerned with the gene-specific induction exhibited by E2 isomers will be pursued by examining the ability of each estrogen analogue to activate the CAT gene in MCF-7 cells transfected with plasmid constructs in which CAT expression is regulated by different EREs or other regulatory elements. The abnormal activity of specific estrogen analogues will also be examined in experiments which document variances in transcription rate, half-life of mRNAs of gene products, and the effect of estrogen structure on ER dimer formation. Knowledge gained from these studies will contribute to the understanding of gene regulation by estrogens and aid in the design of attenuated estrogens for use in the treatment of hormone dependent neoplasms.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA044771-06
Application #
3187564
Study Section
Reproductive Endocrinology Study Section (REN)
Project Start
1987-04-15
Project End
1994-12-31
Budget Start
1993-01-01
Budget End
1993-12-31
Support Year
6
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Wayne State University
Department
Type
Schools of Medicine
DUNS #
City
Detroit
State
MI
Country
United States
Zip Code
48202
Brooks, Sam C; Skafar, Debra F (2004) From ligand structure to biological activity: modified estratrienes and their estrogenic and antiestrogenic effects in MCF-7 cells. Steroids 69:401-18
Davis, M D; VanderKuur, J A; Brooks, S C (1999) Ligand structure influences autologous downregulation of estrogen receptor-alpha messenger RNA. J Steroid Biochem Mol Biol 70:27-37
Schwartz, J A; Liu, G; Brooks, S C (1998) Genistein-mediated attenuation of tamoxifen-induced antagonism from estrogen receptor-regulated genes. Biochem Biophys Res Commun 253:38-43
Schwartz, J A; Brooks, S C (1997) Neutral mutations to three acidic AF2 residues in the mouse estrogen receptor confer agonist activity to A-ring isomers of estradiol. J Steroid Biochem Mol Biol 62:173-84
Wiese, T E; Polin, L A; Palomino, E et al. (1997) Induction of the estrogen specific mitogenic response of MCF-7 cells by selected analogues of estradiol-17 beta: a 3D QSAR study. J Med Chem 40:3659-69
Palomino, E; Heeg, M J; Pilat, M J et al. (1996) Crystal structure, receptor binding, and gene regulation of 2- and 4-nitroestradiols. Steroids 61:670-6
Pilat, M J; Christman, J K; Brooks, S C (1996) Characterization of the estrogen receptor transfected MCF10A breast cell line 139B6. Breast Cancer Res Treat 37:253-66
Wiese, T E; Dukes, D; Brooks, S C (1995) A molecular modeling analysis of diethylstilbestrol conformations and their similarity to estradiol-17 beta. Steroids 60:802-8
Davis, M D; Butler, W B; Brooks, S C (1995) Induction of tissue plasminogen activator mRNA and activity by structurally altered estrogens. J Steroid Biochem Mol Biol 52:421-30
Christman, J K; Nehls, S; Polin, L et al. (1995) Relationship between estrogen structure and conformational changes in estrogen receptor/DNA complexes. J Steroid Biochem Mol Biol 54:201-10

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