University of New Mexico UNM Digital Repository Biomedical Sciences ETDs Electronic Theses and Dissertations 5-1-2010 Identification and characterization of steroid receptor ligands Megan Dennis Follow this and additional works at: https://digitalrepository.unm.edu/biom_etds Recommended Citation Dennis, Megan. "Identification and characterization of steroid receptor ligands." (2010). https://digitalrepository.unm.edu/ biom_etds/11 This Dissertation is brought to you for free and open access by the Electronic Theses and Dissertations at UNM Digital Repository. It has been accepted for inclusion in Biomedical Sciences ETDs by an authorized administrator of UNM Digital Repository. For more information, please contact [email protected]. i by DISSERTATION Submitted in Partial Fulfillment of the Requirements for the Degree of The University of New Mexico Albuquerque, New Mexico ii ACKNOWLDEGEMENTS First, I would like to thank my parents, Mary and Greg. Without their guidance and support throughout the years this document would not exist. Thank you. Secondly, I would like to thank my mentor, Dr. Eric Prossnitz. Eric has always been involved to the perfect degree in my research, staying out of the way and letting me learn to be an independent researcher but also always there to give advice and help me find my way. Throughout my career, I hope to be as effective a mentor to students as Eric has been for me. Next, I would like to acknowledge my committee members, who have all been involved extensively with different parts of this work. Dr. Larry Sklar taught me a great many things about flow cytometry, presenting data and fielding questions. He also told me very early in my graduate work to keep my computer files organized and as I near the end of my time as a student, I realize that this may be the most valuable lesson of all. Dr. Todd Thompson has introduced me to the world of the androgen receptor and developing the MARS assay with his group restored my faith in my own ability to be a successful scientist when estrogen research appeared bleak. His Star Trek references and conversations with Eric also provided me with endless entertainment during meetings. Finally, I must thank Dr. Helen Hathaway, who has always provided a view from the ‘mouse people’ and has helped keep me grounded in the bigger physiological picture beyond chemical compounds and cell lines. Finally, I would like to thank all of my co-workers, who are too numerous to name but who have all helped me with techniques, problems and making sense of the whole grad school experience. iii by ABSTRACT OF DISSERTATION Submitted in Partial Fulfillment of the Requirements for the Degree of The University of New Mexico Albuquerque, New Mexico iv IDENTIFICATION AND CHARACTERIZATION OF STEROID RECEPTOR LIGANDS by Megan Kathleen Dennis B.S., Biology, Gonzaga University, 2004 Ph.D., Biomedical Sciences, University of New Mexico, 2010 ABSTRACT This work focuses on steroid receptors, including the androgen receptor (AR), the estrogen receptors (ERs) ERα and ERβ, known as the classical ERs, and GPR30, a recently described G protein-coupled estrogen receptor. Each of these receptors plays a role in many normal tissues and disease pathologies and signaling through steroid receptors is required for growth of many cancers. Additionally, many tissues express more than one estrogen receptor, making delineation of the functions of individual receptors difficult. We have previously identified a GPR30-selective agonist, G-1, and this small molecule has been shown to mediate GPR30 function in a range of in vitro and in vivo systems. Thus, selective mediators of steroid receptor function do exist and will be useful in characterizing receptor function and in investigating therapeutic potential of each receptor individually. We hypothesize that the identification of novel estrogen and androgen receptor ligands will result in further elucidation of steroid receptor function in complex systems. To address the possibility that additional selective ligands for steroid receptors exist, we first optimized a series of AR assays for investigation of a v library of small molecules to search for novel AR-mediating functions. Subsequently, high-throughput screening was used to search for selective estrogen receptor ligands and this search identified a small molecule antagonist of GPR30, G15. Follow-up characterization of G15 as well as synthetic chemistry based on the structural similarities resulted in a second-generation GPR30 antagonist, G36, which has increased specificity for GPR30 versus ERα/ERβ. These compounds were used to probe the function of GPR30 in glioma and we find that GPR30 is the functionally important estrogen receptor in this system, regulating the response of glioma cells to both estrogen and tamoxifen. Finally, two series of GPR30-targeted in vivo imaging agents were generated and characterized for biological activity prior to small animal imaging. This work demonstrates the necessary processes involved for small molecule discovery and characterization, as well as several applications for receptor-specific small molecules beyond their initial identification. vi TABLE OF CONTENTS ACKNOWLDEGEMENTS .............................................................................................iii ABSTRACT....................................................................................................................... v TABLE OF CONTENTS ............................................................................................... vii LIST OF FIGURES .......................................................................................................xiii ABBREVIATIONS ........................................................................................................ xvi 1 INTRODUCTION........................................................................................................... 1 1.1 Physiological importance of steroid hormones .................................... 2 1.2 Receptors for E2 and DHT........................................................................... 5 1.3 Genomic signaling through estrogen and androgen receptors........ 9 1.4 Non-genomic signaling through estrogen and androgen receptors . ........................................................................................................................... 11 1.5 Introduction to aberrant signaling of steroid receptors in cancer . 16 1.6 Introduction to estrogen and androgen receptor ligands................. 23 1.7 Introduction to high throughput screening .......................................... 25 1.8 Introduction to in vivo tumor imaging.................................................... 28 1.9 Rationale for project.................................................................................... 32 2 ANDROGEN RECEPTOR SCREENING................................................................ 35 2.1 Introduction ................................................................................................... 35 2.2 A multifunctional androgen receptor screening (MARS) assay using the high-throughput HyperCyt® flow cytometry system .................. 40 2.2.1 ABSTRACT............................................................................................. 41 2.2.2 INTRODUCTION.................................................................................... 43 2.2.3 RESULTS................................................................................................ 47 2.2.4 DISCUSSION.......................................................................................... 53 2.2.5 MATERIALS & METHODS .................................................................. 61 2.2.5.1 Chemicals....................................................................................... 61 2.2.5.2 Expression vectors...................................................................... 61 2.2.5.3 Cell culture & transfection......................................................... 61 2.2.5.4 Transcriptional activation assays ........................................... 62 2.2.5.5 Microscopic analysis .................................................................. 62 2.2.5.6 HyperCyt® analysis..................................................................... 63 2.2.6 FIGURE LEGENDS............................................................................... 64 2.2.6.1 Figure 2.1. Methods of analysis using the MARS assay ... 64 2.2.6.2 Figure 2.2. MARS assay analyzed by microscopy .............. 64 2.2.6.3 Figure 2.3. Chemical structures of the test set of compounds used for MARS assay validation.......................................... 65 2.2.6.4 Figure 2.4. Androgenic activity of compounds in a single- dose MARS assay ............................................................................................ 65 2.2.6.5 Figure 2.5. Dose-response curves for AR agonists in the MARS assay....................................................................................................... 66 2.2.6.6 Figure 2.6. Dose-response curves for AR antagonists in the MARS assay ............................................................................................... 66 2.2.6.7 Table 2.1. EC50 and IC50 Values for MARS ............................. 66 2.3 Segue............................................................................................................... 74 vii 2.4 AR / ICCVAM Screening Section.............................................................. 75 2.4.1 ABSTRACT............................................................................................