It is clear from the results of the Women's Health Initiative that there is an unmet medical need for estrogens that manifest their activity in a tissue-selective manner. Indeed, drugs with these properties like the SERMs raloxifene, bazedoxifene and lazofoxifene have already been developed. Unfortunately, none of these SERMs can treat the climacteric symptoms associated with estrogen deprivation. Furthermore, there is concern that long-term exposure to the available SERMs, while reducing the incidence of breast cancer in some women may actually facilitate the growth of cancers in others. Obviously, the next advance in this field will be the development of truly specific SERMs. This will be accomplished by defining the specific coactivators involved in a given process and selectively regulating these interactions with small molecules. With over 40 known ER-interacting proteins already identified, it may seem hard to believe that further discovery in this area is needed. However, our data suggests that there are important gaps in our understanding of ER action and that at least two additional classes of coactivators remain to be identified. To address this issue we have developed a high-throughput protein-protein interaction screen that will allow us to efficiently probe a large number of ER responsive tissues/cells for cofactors involved in determining the molecular pharmacology of estrogens and antiestrogens. In addition, we propose to investigate the mechanism(s) by which the RNA-binding protein RTAa,a cofactor recently identified by our laboratory, exerts its regulatory activities on ERa and determine its role in regulating the cellular responses to estrogens, antiestrogens and SERMs. Reflecting these objectives, we propose the following specific aims:
Aim 1. Identification of factors that interact with ERa-tamoxifen and ERa-estradiol complexes in a manner that is distinct from those previously identified.
Aim 2. Evaluation of the biological consequences of differential ERa-coactivator recruitment.
Aim 3. Elucidation of the molecular mechanism(s) underlying the tissueselective agonist/antagonist activities of tamoxifen.
Aim 4. Definition of the molecular mechanism by which the RNA binding protein RTAct/FXH-1 manifests its regulatory activity on ERa pharmacology.
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|McDonnell, D P; Chang, C-Y; Nelson, E R (2014) The estrogen receptor as a mediator of the pathological actions of cholesterol in breast cancer. Climacteric 17 Suppl 2:60-5|
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|Wardell, Suzanne E; Nelson, Erik R; McDonnell, Donald P (2014) From empirical to mechanism-based discovery of clinically useful Selective Estrogen Receptor Modulators (SERMs). Steroids 90:30-8|
|Nelson, Erik R; Wardell, Suzanne E; Jasper, Jeff S et al. (2013) 27-Hydroxycholesterol links hypercholesterolemia and breast cancer pathophysiology. Science 342:1094-8|
|Wardell, Suzanne E; Nelson, Erik R; Chao, Christina A et al. (2013) Bazedoxifene exhibits antiestrogenic activity in animal models of tamoxifen-resistant breast cancer: implications for treatment of advanced disease. Clin Cancer Res 19:2420-31|
|Nelson, Erik R; Wardell, Suzanne E; McDonnell, Donald P (2013) The molecular mechanisms underlying the pharmacological actions of estrogens, SERMs and oxysterols: implications for the treatment and prevention of osteoporosis. Bone 53:42-50|
|Hu, Peng; Herrmann, Rolf; Bednar, Amanda et al. (2013) Aryl hydrocarbon receptor deficiency causes dysregulated cellular matrix metabolism and age-related macular degeneration-like pathology. Proc Natl Acad Sci U S A 110:E4069-78|
|Pollock, Julie A; Larrea, Michelle D; Jasper, Jeff S et al. (2012) Lysine-specific histone demethylase 1 inhibitors control breast cancer proliferation in ERýý-dependent and -independent manners. ACS Chem Biol 7:1221-31|
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