To date, the rodent ventral prostate (VP) has been the focus of many studies on
androgen action, less attention has been directed to the lateral prostate (LP) and the dorsal prostate (DP). The rodent VP has no clear homologous counterpart in the human prostate. The rodent LP and DP is the only prostate lobe comparable to the peripheral zone of the human prostate, where
hormone-induced
prostate cancer mainly occurs. To explore its utility for prostate targeting, we have studied the gene expression of PSP94 with rat
probasin (rPB), a gene commonly used for prostate targeting in
prostate cancer research and a gene typically responsive to
androgen regulation. Firstly, we demonstrated PSP94 gene transcription being more specific to the LP and DP lobes than rPB, where rPB
RNA was detected in the LP and DP and other lobes at different levels. Secondly, we found that PSP94 gene transcription decreased relatively slowly in response to
androgen deprivation but recovered rapidly in response to
testosterone replacement after complete ablation of PSP94 transcription. In the VP, gene transcripts of rPB were specifically responsive to
androgen deprivation; however, they responded relatively slowly in the LP and DP.
RNase protection experiments indicated that the slow response was not due to abnormal persistence of PSP94
messenger RNA specifically in the DP and LP lobes in comparison with rPB. Thirdly, Western blot analysis revealed that both PSP94 and rPB expression is specific to the LP and DP at the
protein level, exhibiting slow responses to
testosterone replacement after
castration. We conclude that PSP94 gene expression at the transcriptional level is more specific to the LP and DP than rPB and thus less sensitive to
androgen ablation. This may have clinical implications for strategies to target the prostate in
cancer therapy.