The Novel Serine Protease Tumor-Associated Differentially Expressed Gene-15 (Matriptase/MT-SP1) Is Highly Overexpressed in Cervical Carcinoma

BACKGROUND. Tumor-associated differentially expressed gene-15 (TADG-15/matriptase/MT-SP1) is a novel transmembrane serine protease involved in numerous biologic processes, including activation of growth and angiogenic factors and degradation of extracellular matrix components. To assess the value of TADG-15 as a possible marker for tumor detection and/or as a target for therapeutic intervention, the authors investigated the frequency of expression of TADG-15 in human cervical tumors. METHODS. TADG-15 expression was evaluated in 19 cervical carcinoma cell lines (i.e., 11 primary tumor cell lines and 8 established cell lines) and in 8 normal cervical keratinocyte control cultures using reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, to validate gene expression data at the protein level, TADG-15 expression was evaluated by immunohistochemistry on paraffin embedded tissue from which all 11 primary tumor cell lines were established. RESULTS. TADG-15 was expressed at high levels in 8 of 11 (73%) primary cervical carcinoma cell lines and in 6 of 8 (75%) established cervical carcinoma cell lines by RT-PCR. Expression of TADG-15 was found in 6 of 6 (100%) primary squamous cell cervical carcinomas, whereas 2 of 5 (40%) primary adenocarcinomas expressed TADG-15. In contrast, none of the normal cervical keratinocyte control cultures (n = 4) or flash-frozen normal cervical biopsy specimens (n = 4) expressed TADG-15. Immunohistochemistry staining of paraffin embedded cervical carcinoma specimens confirmed TADG-15 expression in tumor cells and its absence on normal cervical epithelial cells. CONCLUSIONS. Cervical carcinoma cells expressed high levels of TADG-15, suggesting that this protease may play an important role in invasion and metastasis. Because TADG-15 appears only in abundance in squamous tumor tissue and contains a proteolytic cleavage site, suggesting that the TADG-15 protease domain is released, it may prove to be a useful diagnostic tool for the early detection of recurrent/persistent cervical carcinoma after standard treatment or as a novel molecular target for therapy in patients with cervical carcinoma.