Prostate Specific Antigen research, Prostate Specific Antigen source

Prostate-specific antigen (PSA) is an androgen-regulated serine protease produced by both prostate epithelial cells and prostate cancer (PCa) and is the most commonly used serum marker for cancer. Prostate specific antigen (PSA) is a protein produced by the cells of the prostate gland. Prostate-specific antigen is present in small quantities in the serum of normal men, and is often elevated in the presence of prostate cancer and in other prostate disorders.

PSA is a major protein in semen , where its function is to cleave semenogelins in the seminal coagulum. PSA is secreted into prostatic ducts as an inactive 244–amino acid proenzyme (proPSA) that is activated by cleavage of seven N-terminal amino acids. PSA that enters the circulation intact is rapidly bound by protease inhibitors, primarily alpha1-antichymotrypsin, although a fraction is inactivated in the lumen by proteolysis and circulates as free PSA

A PSA blood test is the most effective test currently available for the early detection of prostate cancer. Higher than normal levels of PSA are associated with both localized and metastatic prostate cancer (CaP).