Cloning of tumor-associated differentially expressed gene-14, a novel serine protease overexpressed by ovarian carcinoma

The family of enzymes known as serine proteases supports many biological fu nctions for cancer cells, including activation of growth and angiogenic fac tors and activation of other proteases for invasion and metastasis, In addi tion, many of these serine proteases are secreted by cells into the extrace llular space to serve these functions. Therefore, serine proteases are exce llent candidate tumor markers. To examine serine proteases expressed by ova rian carcinoma, we designed degenerate PCR primers corresponding to the con served regions of these genes and used them in reverse transcriptase-PCR ex periments with normal and tumor cDNA as a template, The PCR products were s ubcloned and sequenced, and one of these clones was found to encode a novel serine protease, named tumor-associated differentially expressed gene-14 ( TADG14), Northern blot analysis indicated that the mRNA for TADG14 is 1.4 k b long and that it is highly overexpressed in ovarian carcinoma compared wi th normal ovary, The entire cDNA has been obtained, and based on sequence h omology, it encodes a 260-amino acid serine protease, Semiquantitative PCR indicates that TADG14 is overexpressed in 24 of 40 tumors studied. Northern blot data confirm this overexpression, and immunohistochemical staining su ggests that this protein is secreted, As such, the TADG14 protease may be u seful as a diagnostic tool or as a molecular target for therapy.