Expression of the protease inhibitor antileukoprotease and the serine protease stratum corneum chymotryptic enzyme (SCCE) is coordinated in ovarian tumors.

We have previously reported that the stratum corneum chymotryptic enzyme (SCCE) is overexpressed in ovarian cancers and that SCCE has potential as a useful marker and/or a therapeutic target for ovarian carcinoma. Antileukoprotease (ALP) has been shown to be a specific inhibitor of SCCE. The objective of this study was to investigate the potential cotranscription and overexpression of ALP in carcinoma of the ovary. The expression of ALP transcript was evaluated by Northern blot hybridization and by semiquantitative polymerase chain reaction (PCR) technique. The presence of the ALP protein in ovarian tumor cells was evaluated by immunohistochemistry. Northern blot hybridization showed that the ALP transcript was abundant in ovarian carcinomas but was not detected in the normal ovary. Semi-quantitative PCR examination revealed that the mRNA level of ALP was significantly elevated in low-malignant-potential tumors and in ovarian carcinomas compared with that in normal ovaries (P < 0.01). There was significant positive correlation between SCCE and ALP mRNA overexpression status in ovarian tumor cases (P < 0.01). Immunohistochemical expression of ALP protein was observed in ovarian tumor cells, whereas little or no staining was observed in normal ovarian surface epithelium. Like SCCE, ALP is highly overexpressed in ovarian tumor cells, which begs the question of whether it remains an effective inhibitor of SCCE or whether it is discordant in time or space and is ineffective as an inhibitor of the SCCE enzyme.