Prostasin regulates iNOS and cyclin D1 expression by modulating protease-activated receptor-2 signaling in prostate epithelial cells.

BACKGROUND

Prostasin is down-regulated during inflammation and in invasive cancers, and plays a role in regulation of inflammatory gene expression and invasion.

METHODS

We used the human benign prostatic hyperplasia cell line BPH-1 to investigate gene expression changes associated with siRNA-mediated loss of prostasin expression. Quantitative PCR and/or western blotting were used to evaluate the expression changes of iNOS, ICAM-1, cyclin D1, IL-6, and IL-8. Gene expression changes were also evaluated in the presence of a PAR-2 antagonist. The PC-3 human prostate cancer cell line was used for evaluation of gene expression in response to prostasin re-expression.

RESULTS

Prostasin silencing in BPH-1 was associated with up-regulation of iNOS, ICAM-1, IL-6, and IL-8, and down-regulation of cyclin D1; as well as reduced proliferation and invasion. The iNOS up-regulation and cyclin D1 down-regulation associated with prostasin silencing were inhibited by a PAR-2 antagonist. Re-expression of prostasin, a serine active-site mutant, and a GPI-anchor-free mutant, in the PC-3 cells resulted in PAR-2 and cyclin D1 transcription up-regulation. Transcription up-regulation of IL-6 and IL-8 was associated with re-expression of the serine active-site mutant prostasin in the PC-3 cells. Transcription up-regulation of IL-8, but to a lesser extent, was also observed in PC-3 cells expressing the wild-type prostasin. Expression of a serine protease active prostasin, GPI-anchored or anchor-free, prevented the IL-6 induction in response to PAR-2. The GPI-anchor-free prostasin also prevented the IL-8 induction.

CONCLUSIONS

Prostasin plays a negative regulatory role on PAR-2-mediated signaling in prostate epithelial cells.