Regulation of PDE 5 expression in normal prostate, benign prostatic hyperplasia, and adenocarcinoma

Background Type 5 phosphodiesterase ( PDE 5) expression in the normal and pathological prostate is controversial. Objectives This study aimed at identifying the cell type/s, if any, expressing PDE 5 in human healthy or pathological prostate sections in order to further validate the rationale of PDE 5 inhibitor ( PDE 5i) treatment of benign prostatic hyperplasia ( BPH ) and their safety in the treatment of erectile dysfunction following prostate cancer ( PC a) surgery. Materials and methods By immunohistochemical analysis, we studied PDE 5 expression in tissue microarrays containing sections obtained from healthy, BPH , and PC a samples. Results Our results showed that PDE 5 is barely expressed in the epithelial or stromal compartment of normal human prostates, but it is highly expressed in the stromal compartment of BPH sections. We also found that a low but significant number of PC a samples (22%) expressed PDE 5 in the epithelial cancer cells but not in stromal cells and that such expression was not correlated with the tumor aggressiveness, according to their Gleason score. Discussion and conclusion PDE 5 overexpression in the stromal compartment of BPH samples supports the rationale of PDE 5 as a target in lower urinary tract symptoms of BPH . PDE 5 expression in a significant percentage of PC a samples but the lack of correlation with the Gleason score suggests that this enzyme is not correlated with tumor aggressiveness; however, a role of PDE 5 in the minimal residual disease of PC a cannot be excluded.