New tools for controlling nuclear receptor function

Nuclear receptors (NRs) are small molecule dependent transcription factors that play an important role in cell development and homeostasis. Due to NRs role in many diseases and normal physiological processes, they targets for the development of pharmacological agents. New methods are needed that target the function of NRs as well as in elucidating their function. The androgen receptor (AR) is a member of the steroid hormone receptor family and is the primary target for the treatment of advanced prostate cancer used as a model in the current study. All current antiandrogens are subject to clinical failure, due to the development of antiandrogen resistant prostate cancer. The ability for compounds to block AR nuclear localization is directly correlated with their ability to prevent formation of resistant colonies in vitro. To arrest the translocation of the AR to the nucleus, antiandrogen-dendrimer conjugates were developed which use multivalency and molecular size to inhibit the translocation. These conjugates were found to readily enter the cells but not the nucleus. Antiandrogen dendrimer conjugates were observed to inhibit the nuclear translocation of AR in the presence of dihydroxytestosterone (DHT). Acetylation of lysines on the surface of steroid hormone receptors has been known to modulate hormone responsive behavior and is associated with a number of drug resistant cancers. By using artificial acyl transferring agents charge on the surface of the protein could be changed and thereby protein function could be modulated. As natural protein acyltransferases function largely through proximity directed reactions, we have designed reactive ligand conjugates that bind to the AR and place reactive thioesters in proximity to surface lysines. These ligand-thioester conjugates effect a selective acyl transfer to AR which is not observed when the ligand and thioester are not covalently linked. The acylation was observed initially in whole cell lysates and the strategy has been extended in developing catalytic acetyl transferring agents that function inside the cells.