Using microarray-based profiling of isogenic prostate cancer xenograft models, we found that a modest (2-5 fold) increase in androgen receptor (AR) mRNA was the only expression change consistently associated with developing resistance to anti-androgen therapy. Increased levels of AR confer resistance to anti-androgens by amplifying signal output from low levels of residual ligand and altering the normal response to antagonists. This invention provides cell based assays for use in the examination of new therapeutic modalities and provides insight toward the design of novel anti-androgens.
