Overexpression of testisin, a serine protease expressed by testicular germ cells, in epithelial ovarian tumor cells.

OBJECTIVE

In a continued effort to identify and characterize secreted proteases that are overexpressed in ovarian carcinomas, we discovered the testisin protease as such a candidate. When this discovery was originally made, no data existed in the literature or in the GenBank database that identified such a gene. Our main objective was to determine whether this gene was overexpressed exclusively in ovarian tumor tissues compared with normal ovary and whether it was expressed in any other normal tissues.

METHODS

mRNA was isolated and cDNA was prepared from 34 ovarian tumors (four adenomas, three low malignant potential tumors, and 27 carcinomas) and seven normal ovaries. The testisin mRNA expression level relative to internal control, beta-tubulin, was determined by Northern blot analysis and semiquantitative polymerase chain reaction (PCR).

RESULTS

Northern blot hybridization showed that the testisin transcript was abundant in ovarian carcinoma but was not detected in normal ovary. On examination of Northern blots from normal fetal and adult tissues, only adult testis showed abundant transcripts of testisin. Semiquantitative PCR examination showed that the testisin mRNA levels in ovarian tumors of low malignant potential and in ovarian carcinomas were significantly higher than in normal ovaries (P <.01). Testisin mRNA level in ovarian carcinomas was also significantly higher than in ovarian adenomas (P <.05). Testisin overexpression rates in advanced stage (stage 2 or 3) diseases were significantly higher than that in early stage diseases (stage 1) in ovarian carcinoma samples (P <.05).

CONCLUSIONS

The induction of the testisin transcript might contribute to the development, progression, and invasive or metastatic capacity of ovarian carcinomas.