Bone is the most common metastatic site for prostate cancer. Once these tumors have spread to bone, the cancer becomes incurable, thus we need to better understand how tumors get to and grow in the bone. We have recently established a cross Canada collaboration with an expert in protease activated receptor (PAR) proteins. These proteins can regulate many processes that are required to promote growth of tumors that have spread to other parts of the body, but to date no one has shown they affect prostate tumor growth in the bone. We will examine whether genetic deletion of two of these PAR proteins, PAR1 and PAR2, in prostate tumor cells affects their abilty to spread to and grow in the bone. We will also test whether blocking the activity of these proteins using available drugs affects prostate tumor growth in the bone. In this way we will generate data that would be required to move forward to test whether these PAR proteins could be targets to help prevent prostate tumor growth in the bone in patients in the future.