Selective AR Modulators that Distinguish Proliferative from Differentiative Gene Promoters
Technical Report,30 Jul 2015,29 Jul 2016
University of Michigan Ann Arbor United States
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Androgen signaling via its receptor, AR, is a key therapeutic target in prostate cancer. Despite new treatments, resistance is a huge problem. Our goal is to inhibit AR target genes that drive cancer growth but not those for normal cell survival. Our hypothesis is that these sets of genes differ in androgen response elements AREs, with genes driving proliferation relying on consensus inverted repeats cARE and genes promoting differentiation relying on selective direct repeats or half-sites sAREs. To identify compounds that may interact with AR to affect DNA recognition, we developed a high-throughput screen for compounds eliciting different AR activity on cARE vs. sARE reporters. Over 10,000 compounds were tested. Doxorubicin proved best at differentially affecting AR-dependent gene expression in LNCaP cells, by interacting with DNA rather than directly with AR. Doxorubicin is known to elicit DNA damage response, a pathway also influenced by AR. We used protein-DNA interaction assays to show the differential effect of dox on AR binding in vitro, and have extended this to show selectivity of AR binding in vivo by chromatin immunoprecipitation ChIP studies. Further, we have extended our findings of differential gene action by dox to novel regulatory interactions between AR and known tumor suppressors and oncogenes.
- Medicine and Medical Research