Down-regulation of androgen-receptor and PSA by phytochemicals.

The androgen receptor (AR) signaling pathway continues to be active in hormone resistant prostate cancer (HRPC) and can inappropriately activate transcription. Consequently the AR is a therapeutic target for HRPC. We reported that PC-SPES is active against HRPC, partly due to its actions in down-regulating AR protein expression and modulating cell cycle. Further investigation has identified five active anticancer compounds. This study describes the effects of three of these compounds (oridonin, isoliquiritigenin and wogonin) on cell proliferation, cell apoptosis, cell cycle parameters, AR and PSA protein expression. In each case, these compounds have independent activities which may partly contribute to the biological activity of PC-SPES.