Objective: 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 PCa1. Because proteases are involved in almost all cancer associated mechanisms such as cell proliferation, invasion and metastasis, we are interested in their modulation in PCa after ADT and their involvement in CRPC.
Method: First, we screened for protease expression in hormone sensitive prostate cancer cells (LNCaP) after ADT treatment using a custom PCa microarray. Secondly, using RT-qPCR, western-blots and immunofluorescence staining, we confirmed the deregulation of several interesting proteases which are repressed by androgen but induced after ADT. Then, using a model of LNCaP cells knock-down for androgen-receptor (AR), we confirmed involvement of this signaling pathway in regulation of their expression. Finally, we analyzed their expression in C4-2B cells (LNCaP derived CRPC), in other androgen sensitive PCa cell lines and in Oncomine database.
Results: We identified several proteases overexpressed in LNCaP cells after ADT since AR is involved in their expression regulation. Several of them, are already proposed as involved in the aggressiveness of PCa or other cancers: BMP1, TLL1 and TLL2, three proteases of the astacin family; MMP16, a membrane bound MMP; DPP7, a dipeptidyl-peptidase and KLK14, a protease of the same family as PSA. We also showed that several of these proteases are over-expressed in C4-2B cells compared to LNCaP cells and in clinical samples.
Conclusion: Androgen deprivation in PCa is conducive to the deregulation of protease gene expression with the overexpression of several proteases known to be associated with aggressiveness of PCa or other cancers2-5. In vitro and in vivo confirmation of their role in the androgen deprived environment as seen with ADT will determine their potential utilisation as therapeutic targets for CRPC.