Prostate cancer (PC) is the most common cancer in men and the third leading cause of cancer death. In dogs, PC is an uncommon disease, presenting independency of androgen stimulation, with high metastasis rate and high Gleason score. Thus, dogs can be considered a good model for human PC with high Gleason and refractory to hormonal therapy. In men, prostatic specific antigen (PSA) is considered one of the main serum markers for diagnosis of response to therapy. In dogs, serum PSA is not associated with diagnosis and/or prognosis. Some researchers have demonstrated the expression of PSA in canine prostate tissue samples to identify the cell origin of canine PC. However, the expression of PSA by prostatic tissue is controversial. Previously, our research group demonstrated the expression of PSA in canine prostatic tissue and metastases. Indicating PSA immunohistochemistry to identify the prostatic origin in metastases of carcinomas of unknown origin. Due the ambiguous role of PSA expression in canine prostatic tissue, this research aims to identify, characterize and validate PSA as a diagnostic marker of canine prostatic tissue samples. For this, we propose to perform proteomics techniques to identify and characterize the PSA protein in the dog, and then, perform the mass spectrometry to validate the cross-reaction of anti-human PSA antibody with the PSA protein in dogs. After identification and characterization of the PSA in the dog, we also propose the protein validation of the antibody in a large group of canine samples (80 samples) arranged on a TMA slide. Establishing the PSA expression pattern in different canine prostatic lesions. With the results of the research, we intend to establish the PSA as a diagnostic marker of different canine prostatic lesions, supporting the identification of the origin (luminal cell versus urothelial cell) of PC in dogs.
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