Novel Small Molecule Antagonists of the Interaction of the Androgen Receptor and Transcriptional Co-regulators
Annual summary rept. 1 Jan 2007-31 Dec 2008
SAINT JUDE CHILDREN'S RESEARCH HOSPITAL MEMPHIS TN
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Androgens, mediated by the Androgen Receptor AR, play a crucial role in prostate cancer. Current treatments are focused on anti-androgenic drugs competing with natural androgens and antagonizing the transcriptional activity of the AR. Although widely used, these drugs have shown significant side effects and in addition, tumors have become resistant suggesting mutations of the receptor. Regulation of gene expression by AR requires the binding to androgens or to its natural ligand, dihydrotestosterone DHT, and assembly of coregulatory proteins CoR. The blockage of the interaction between DHTliganded AR and CoR by small molecules has been shown to inhibit gene transcription. Thus, novel approaches to inhibit AR activity by means other than ligand binding could have a significant clinical impact. Preliminary data revealed that non-steroidal anti-inflammatory drugs, like flufenamic acid FLF, block AR transcriptional activity but dont displace androgens. We developed small molecule structural analogs of FLF that inhibit AR transcription activity in the nanomolar range and act on AR target genes. We demonstrated an AR antagonism in vitro transcription assays, binding assays that is different from ligand competition. Multiple lines of evidence presented here suggest that compounds function by a distinct mechanism than the current marketed anti-androgens drug combination studies. An early pharmacological profile of these small inhibitors has been characterized cytotoxicity, cell permeability. We provide the first class of small molecules able to inhibit AR transcription activity without androgen competition. Those small molecule inhibitors represent powerful assets to study the mechanism of AR transcriptional function and a new potential therapeutic modality for prostate cancer treatment.
- Genetic Engineering and Molecular Biology
- Anatomy and Physiology
- Medicine and Medical Research