The majority of human
prostate cancer cell lines, including the two "classical" cell lines DU-145 and PC-3, are reported to be
androgen receptor (AR)-negative. However, other studies have provided evidence that the DU-145 and PC-3 cell lines express AR
mRNA. These contradictory observations prompted us to investigate whether DU-145 and PC-3 cell lines express the
androgen receptor. Using antipeptide
antibodies directed against three distinct regions of the
human AR protein and an improved method to detect AR
protein in immunoblotting, we report that DU-145 and PC-3 cell lines express AR
protein. We found that the relative levels of the AR
mRNA and
protein that were detected in DU-145 and PC-3 cell lines were lower than the LNCaP, an AR-positive cell line. Moreover, the antibody directed against the non-variant region (
amino acids 299-315), but not the variant N- or C-terminal region (
amino acids 1-20 and 900-919, respectively) of the
human AR protein, detected the expression of AR in all
prostate cancer cell lines. Notably, treatment of these cell lines with
dihydrotestosterone (DHT) resulted in measurable increases in the AR
protein levels and considerable nuclear accumulation. Although, treatment of DU-145 and PC-3 cells with DHT did not result in stimulation of the activity of an AR-responsive reporter, knockdown of AR expression in PC-3 cells resulted in decreases in p21(CIP1)
protein levels, and a measurable decrease in the activity of the p21-luc-reporter. Our observations demonstrate the expression of AR
protein in DU-145 and PC-3
prostate cancer cell lines.