To present our recent observations obtained from the continuing characterization of the TSP50 gene pertaining to its evolutionary importance and behavior in human testicular germ cell tumors. Previous studies have reported that expression of the human TSP50 gene is testes specific. Its product is similar to many serine proteases but possesses its own unique features. In addition, TSP50 is abnormally activated in most tested patients with breast cancer.

Testicular tissue from rats, mice, and humans was obtained through biopsy or orchiectomy. The expression of the TSP50 protein was determined using immunohistochemical staining and Western blotting techniques.

The Western blot results showed that the polyclonal anti-human TSP50antibody reaction pattern in both rodent testes was the same as that observed in the human testes. In addition, the immunohistochemical staining patterns in the human, mouse, and rat testes were similar. We also discovered that expression of TSP50 was largely downregulated in all testicular germ cell tumors examined by immunohistochemical analysis.

The results of our studies suggest that the TSP50 gene could be of evolutionary importance in mammalian reproduction. Unlike the results generated from patients with breast cancer, in whom upregulation of the TSP50 gene correlates with disease development, the TSP50 gene was downregulated in patients with seminoma. This information indicates that altered expression levels of the TSP50 gene in different microenvironments are associated with different or distinct types of human cancer.