Login to Access Video or Poster Abstract: MP17-03
Sources of Funding: Urology Care Foundation, SESAUA and Miami VA Medical Center

Introduction

The pathogenesis of benign prostatic hyperplasia (BPH) has been associated with various factors including hormonal imbalance, inflammation-induced cell proliferation and epithelial-to-mesenchymal transition. We have previously demonstrated that prostatic GHRH and its receptors are upregulated in a rat testosterone-induced BPH model and GHRH antagonists suppress the levels of proinflammatory cytokines. Based on these findings, we investigated the role of GHRH in inflammation-induced proliferation of prostate epithelial cells in vitro and prostate enlargement in experimental autoimmune prostatitis.

Methods

Autoimmune inflammation in the prostates of Balb/c mice was induced by subcutaneous injections of rat male tissue homogenate. Changes in prostate volume were measured with the VEVO® 1100 ultrasound imaging system. Human BPH-1 and primary prostate epithelial cells were used in matrigel-embedded 3D cultures and average sphere diameters were evaluated. Chronic inflammation was mimicked by treating cells with THP-1 macrophage-conditioned medium or Il-17A, whereas EMT was triggered with TGF-?1 or TGF-?2 peptides. The role of secreted GHRH in inflammation-induced proliferation was determined by using GHRH antagonists developed in our lab. Changes in the protein levels were determined by western blot.

Results

Experimental autoimmune prostatitis increased the volume of the ventral prostate by 92% at week 8 compared to control (p<0.001). A 1-month daily treatment with GHRH antagonists caused a significant, 48% reduction in prostate volume. Macrophage-conditioned medium induced a 26% increase (p<0.001) in the average diameter of cells and elevation in the expression of mesenchymal markers. The mRNA and protein expression of GHRH were significantly increased by macrophage-conditioned medium. GHRH antagonist reduced inflammation- and TGF-?2-induced increase in diameter by 64% (p<0.01) and by 67% (p<0.001), respectively, and reduced the expression of n-cadherin. The stimulatory effect of TGF-?2 was abolished when GHRH receptor expression was silenced by stable transfection of shRNA. IL-17A stimulation of the growth of primary epithelial cells were also significantly reduced by GHRH antagonists.

Conclusions

Our results indicate that GHRH is a key factor in prostatic inflammation-induced prostate enlargement and EMT and suggest that GHRH antagonists have beneficial effects in chronic prostatitis and BPH.

Funding

Urology Care Foundation, SESAUA and Miami VA Medical Center