The actions of progesterone, a hormone of central importance in controlling the function and growth of female reproductive tissues, such as the breast and uterus, appear to be mediated via interaction with an intracellular protein, the progesterone receptor (PR). Although much is known about the nature of this protein, little is known about the synthesis and degradation of PR and factors that regulate these rates. Our initial studies have provided evidence for a biosynthetic, non hormone-binding precursor of PR and for differences in the form of PR when it is associated with the antiprogestin RU486 vs progestin.
Our aims are to study hormonal factors involved in regulation of PR levels and turnover, to investigate biosynthetic precursors of PR, and to examine the nature of nuclear PR complexes. We will use the density shift technique to examine how turnover kinetics are affected by the nature of the ligand (progestin vs antiprogestin) and the level of receptor occupancy. We will compare systems in which PR is under estrogen control (MCF-7 human breast cancer and rat uterine cells) and independent of estrogen (T47D human brease cancer cells). We will utilize a kinetic model, from which the PR precursor pool size and biosynthetic, activation and degradation rate constants can be derived, and we will attempt to characterize the precursor using monoclonal antibodies to PR. These approaches will also enable us to address the important issue of whether estradiol increases PR levels by changes in receptor synthesis, precursor activation, or stabilization of PR. Since we have found that nuclear PR complexes with antiprogestin sediment as 6 S species under conditions where the complexes with progestin are exclusively 4 S, we will examine factors that affect the 6 S/4 S ratio, determine the subunit composition of the 6 S species by crosslinking and photoaffinity labelling, and evaluate whether the 6 S species represents an """"""""unactivated"""""""" non-DNA binding form of PR. These studies should provide new information on the biosynthesis and degradation of this important regulatory protein, and on the receptor interactions that may underlie progestin antagonist action.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA051482-06
Application #
3196227
Study Section
Biochemical Endocrinology Study Section (BCE)
Project Start
1989-12-01
Project End
1994-11-30
Budget Start
1991-12-01
Budget End
1992-11-30
Support Year
6
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Illinois Urbana-Champaign
Department
Type
Schools of Arts and Sciences
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
Montano, M M; Ekena, K; Krueger, K D et al. (1996) Human estrogen receptor ligand activity inversion mutants: receptors that interpret antiestrogens as estrogens and estrogens as antiestrogens and discriminate among different antiestrogens. Mol Endocrinol 10:230-42
Kraus, W L; Weis, K E; Katzenellenbogen, B S (1995) Inhibitory cross-talk between steroid hormone receptors: differential targeting of estrogen receptor in the repression of its transcriptional activity by agonist- and antagonist-occupied progestin receptors. Mol Cell Biol 15:1847-57
Herman, M E; Katzenellenbogen, B S (1994) Alterations in transforming growth factor-alpha and -beta production and cell responsiveness during the progression of MCF-7 human breast cancer cells to estrogen-autonomous growth. Cancer Res 54:5867-74
Aronica, S M; Kraus, W L; Katzenellenbogen, B S (1994) Estrogen action via the cAMP signaling pathway: stimulation of adenylate cyclase and cAMP-regulated gene transcription. Proc Natl Acad Sci U S A 91:8517-21
Cho, H; Aronica, S M; Katzenellenbogen, B S (1994) Regulation of progesterone receptor gene expression in MCF-7 breast cancer cells: a comparison of the effects of cyclic adenosine 3',5'-monophosphate, estradiol, insulin-like growth factor-I, and serum factors. Endocrinology 134:658-64
Kraus, W L; Montano, M M; Katzenellenbogen, B S (1994) Identification of multiple, widely spaced estrogen-responsive regions in the rat progesterone receptor gene. Mol Endocrinol 8:952-69
Fujimoto, N; Katzenellenbogen, B S (1994) Alteration in the agonist/antagonist balance of antiestrogens by activation of protein kinase A signaling pathways in breast cancer cells: antiestrogen selectivity and promoter dependence. Mol Endocrinol 8:296-304
Le Goff, P; Montano, M M; Schodin, D J et al. (1994) Phosphorylation of the human estrogen receptor. Identification of hormone-regulated sites and examination of their influence on transcriptional activity. J Biol Chem 269:4458-66
Kraus, W L; Montano, M M; Katzenellenbogen, B S (1993) Cloning of the rat progesterone receptor gene 5'-region and identification of two functionally distinct promoters. Mol Endocrinol 7:1603-16
Cho, H; Katzenellenbogen, B S (1993) Synergistic activation of estrogen receptor-mediated transcription by estradiol and protein kinase activators. Mol Endocrinol 7:441-52

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