Activation of rat androgen receptor by androgenic ligands is unaffected by antiandrogens in Saccharomyces cerevisiae

The E. coli lacZ has been utilized as a reporter to evaluate ligand-mediated activation of the rat androgen receptor (AR) in Saccharomyces cerevisiae strain YCR1. β-galactosidase activity was androgen-specific and was found to be inducible ∼260-fold by dihydrotestosterone (DHT), testosterone and R1881. None of the antiandrogens tested was able to antagonize the DHT-dependent induction of β-galactosidase activity. In the gel retardation assay, exposure of the receptor to DHT in vitro led to the formation of a protein–DNA complex that was not detected in yeast extracts unexposed to hormone. However, activation of AR by a steroidal (cyproterone acetate) and a non-steroidal antiandrogen (flutamide) either alone or in combination with DHT also results in a similar migration pattern. Additionally, LEM1, the ABC transporter that selectively modulates the biological potency of steroids in yeast, although operative in YCR1, was not responsible for antiandrogen resistance. These results thus indicate the involvement of other non-receptor factor(s) in mediating the effect of antiandrogens in yeast.