Histochemical analysis of testis specific gene 13 in human normal and malignant tissues.

Testis-specific gene 13 (TSGA13) is abundantly expressed in testis. As previous studies of TSGA13 expression pattern have all been based on mRNA analysis, it is imperative to investigate its actual protein expression. Here, we first examined TSGA13 gene tree and protein homology among species, and found that TSGA13 is relatively well conserved. Next, we detected its protein expression in normal human tissues as well as in a limited number of malignant tumors by immunohistochemistry (IHC). It was demonstrated that, in addition to testis, high expression of TSGA13 could also be observed in multiple normal tissues, including stomach, larynx, spleen, bladder, tonsil, liver and thyroid. Notably, most types of human carcinoma tissues displayed reduced expression of TSGA13 rather than their adjacent normal tissues except glioblastoma and lung cancer. Hence, the data from the current study strongly suggest the association between TSGA13 and tumor malignancy.