Objectives: To investigate the expression of androgen receptor (AR) coactivators in the human prostate for a better understanding of androgen action in prostate cancer.
Methods: Using reverse transcriptase-polymerase chain reaction, we examined the expression levels of AR coactivators (ARA55, SRC1, ARA54, TIF2, RAC3) in four prostate cancer cell lines (DU145, PC3, LNCaP, and LN-TR2), nine benign prostatic tissue samples, and 21 prostate cancer tissue specimens.
Results: In the cell lines, SRC1 was expressed ubiquitously at almost equal amounts. Contrary to this, ARA55, ARA54, TIF2, and RAC3 displayed cell line-specific expression. In the LN-TR2 cells, established from LNCaP cells by long-term treatment with tumor necrosis factor-alpha, the expression levels of ARA55 and TIF2 were much higher than those in the LNCaP cells. In every prostatic tissue specimen, the expression levels of TIF2 and RAC3 were very low. The expression levels of ARA55 and SRC1 were higher in the cancer specimens with a higher grade or poor response to endocrine therapy than in those with a lower grade or good response to endocrine therapy.
Conclusions: Prostate cancer cells express AR coactivators. Long-term stimulation by tumor necrosis factor-alpha could increase ARA55 and TIF2 expression in LNCaP cells. The different expression of coactivators may contribute to the different response of prostate cancer to androgenic stimulation or endocrine therapy.