Targeting androgen receptor (AR) with a synthetic peptide increases apoptosis in triple negative breast cancer and AR-expressing prostate cancer cell lines.

BACKGROUND: The androgen receptor (AR) has been studied as an approach to cancer therapy. AIMS: We used human breast cancer-derived cells with high, low, and very low expression levels of AR, in addition to prostate cancer-derived LNCaP and DU-145 cells as a positive and negative controls to examine apoptosis caused by a synthetic peptide that targets ARs. METHODS AND RESULTS: The peptide was produced to inhibit AR transactivation in breast cancer cell lines. We then measured cell viability, caspase-3 activity, and the ratio of Bax/Bcl-2. The findings indicated that the peptide (100-500 nM) in the presence of dihydrotestosterone (DHT) reduced cell growth in cells with high and low expression level of AR (p < .001), but not in cells with very low levels of AR. Treatment with 100-500 nM of peptide activated caspase-3 and increased the ratio of Bax/Bcl-2 in cells with high and low expression levels of AR. Also, increasing concentrations of the peptide (100-500 nM) reduced BrdU incorporation in the presence of DHT and promoted apoptosis in cells with high and low expression levels of AR (p < .001). CONCLUSION: The findings indicate the peptide significantly increased apoptosis in cancer cells.