Protease, Serine 50 (PRSS50)

TSP50 DNA methylation correlated with lack of TSP50 expression in bladder, blood, breast, colon, lung, kidney, placenta, and ovary tissues, while demethylation correlated with its expression in testis. TSP50 was both abnormally hypomethylated and expressed in some breast and ovarian cancers, but not in the corresponding normal tissues.

While TSP50 shares significant identity with several serine proteases, the catalytic serine is replaced by threonine. Immunohistochemical analysis showed TSP50 expressed in spermatocytes, but not in mature sperm. Western blot analysis detected TSP50 in 92% of breast cancer samples tested, but not in normal matched tissues. In situ hybridization confirmed expression of TSP50 in malignant breast cancer cells.