Selective AR Modulators that Distinguish Proliferative from Differentiative Gene Promoters
Technical Report,30 Jul 2016,29 Jul 2017
University of Michigan Ann Arbor United States
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Androgen signaling via the androgen receptor, AR, is a key therapeutic target in prostate cancer. Our goal is to inhibit AR target genes that drive cancer but not normal cell growth to avoid resistance. Our hypothesis is that these genes differ in androgen response elements AREs, with genes driving proliferation relying on consensus inverted repeats cARE and genes promoting differentiation relying on AR-selective direct repeats or half-sites sAREs. To identify compounds that affect ARDNA recognition, we performed a high-throughput screen for compounds eliciting differential AR activity on cARE vs. sARE reporters. Of 10,000 compounds, doxorubicin proved best at differentially affecting AR-driven gene expression, by interacting with DNA rather than directly with AR. This differential effect was pronounced at low doses of dox, leading to induction of sARE-driven genes in contrast to inhibition of cARE-driven genes, in multiple cell lines. Doxorubicin elicits DNA damage response, a pathway also influenced by AR. We used protein-DNA inter-action assays to show the differential effect of dox onAR binding in vitro, and extended this to show selectivity of AR binding in vivo by chromatin immunoprecipitation ChIPstudies. Bioinformatic analysis of ChIP-seq data is ongoing to define genome-wide the set of genes sensitive to low dose dox.
- Medicine and Medical Research