Synthesis and characterization of estradiol analog conjugates

Compared to other types of cancer, breast cancer has one the highest mortality rates for women in the United States. Two major classes of drugs used to treat estrogen receptor (ER) positive breast cancer are the selective estrogen receptor modulators (SERMs), which include drugs such as tamoxifen, and the selective estrogen receptor downregulator (SERD) drugs, such as fulvestrant. While the two classes of drugs seem to differ in how they affect ER stability, the exact mechanisms of SERD and SERM action on cellular estrogen signaling have yet to be determined. Our major goal is to study the effect of subcellular localization on the ability of SERDs to affect cellular estrogen signaling. The overall goal of this project is to develop a fluorescent conjugate that can act as a SERD to be used as a tool to both visualize the fate of a SERD compound in the cell and potentially restrict its subcellular localization. I first developed a novel 11-beta substituted estradiol analog that was able to bind to estrogen receptor in vitro and regulate ER-mediated transcription in cell-based assays. Next, two novel fluorescent conjugates were synthesized and tested for their binding affinity and ability to regulate ER-mediated transcriptional activity. Both conjugates were able to bind to ER in vitro and stimulate ER-mediated transcription in cells, which contradicted our initial design goal of making SERD-like antagonists and our secondary goal of having at least one of them be cell-impermeable. However, this finding may be useful because we have been able to develop an estrogen analog where the attachment of flourescent moeity still allows for the retention of the agonistic activity of estradiol. This can be useful for studying the effect of localization on initial estrogen signaling and the eventual fate of an agonist ligand. Future work is proposed to exploit this finding as well as overcome the technical hurdles in developing a fluorescent SERD