Introduction: Understanding mechanisms associated with the emergence of castration resistant prostate cancer cells (CRPC) after androgen deprivation therapy (ADT) is essential to create new therapeutic agents to counteract this aggressive form of prostate cancer (PCa). We are interested in the modulation of proteases in PCa after ADT and their involvement in CRPC.
Method: We screened for protease expression in hormone sensitive PCa cells after ADT treatment using RNA-sequencing and confirmed protease dysregulation by RT-qPCR and western-blot in several PCa cell lines and in PCa cells knocked-down for the androgen-receptor. By exploiting publicly available databases, we identified that several of these proteases are associated with aggressiveness of PCa such as the kallikrein-related peptidase 14 (KLK14). To determine the function of this protease in PCa cells, we established an inducible KLK14 overexpression model in LNCaP cells. We analysed transcriptome modifications associated with KLK14 expression using microarray and confirmed the dysregulated genes and pathways by RT-qPCR and western blot. Finally, we performed functional assays using PCa cells overexpressing or knocked-down for KLK14 and a KLK14 inhibitor.
Results: We identified several proteases overexpressed in LNCaP cells after ADT. Here, we have focused our work on KLK14 which is upregulated in androgen insensitive and metastatic PCa cells, as well as in patients with high grade and metastatic PCa. We demonstrated that overexpression of KLK14 modulates genes and signalling pathways essential for PCa progression. In addition, we showed that KLK14 increases migration and invasion of PCa cells. Finally, using a specific KLK14 inhibitor, we demonstrated that neutralization of KLK14 proteolytic activity reduces KLK14-mediated aggressiveness of PCa cells.
Conclusion: ADT is conducive to the deregulation of proteases known to be associated with aggressiveness of PCa such KLK14. Targeting these proteases using specific neutralizing agents in combination with androgen-targeting therapy could be beneficial for patients with aggressive PCa.