Testosterone is a potential augmentor of antioxidant-induced apoptosis in human prostate cancer cells

We have investigated the effect of antioxidant-induced apoptosis in human prostate cancer cell lines that is augmented by testosterone (T). In this study, DU-145 (androgen unresponsive), ALVA-101 (partially androgen responsive), and LNCaP (androgen responsive) were grown in tissue culture with RPMI 1640 medium, 5–10% fetal bovine serum (FBS), antibiotics and 5% CO2. Treatment with 2.5–20 μg/ml of PDTC significantly (P<0.05, n=6) lowered cell growth in all three cells 2–60% following treatment for 1–7 days. T (10−12 M) alone enhances cell growth in androgen responsive cells. In contrast, the combination of PDTC and T significantly (P<0.05, n=6) augmented the PDTC induction of apoptosis in the androgen responsive cells, (ALVA-101 and LNCaP), but not in the androgen unresponsive cells (DU-145). PDTC reduced the nuclear NF-κB, as determined with an electrophoretic mobility shift assay (EMSA), to 50% of the control in LNCaP cells, 65% in ALVA-101 cells and 45% in DU-145 cells, but the combination of PDTC and T was not more potent than PDTC alone in any of the cell lines. PDTC suppressed both the AR mRNA and protein expression and reversed the stimulatory effect of T on androgen receptor (AR) protein synthesis in LNCaP and AVLA-101 cells. In conclusion, PDTC is a potent growth inhibitor and an inducer of apoptosis in human prostate cancer cells by reducing nuclear NF-κB and AR protein expression. PDTCs suppression of AR synthesis and nuclear NF-κB in response to T may contribute to its enhancement of apoptosis observed with T and PDTC compared to PDTC alone.