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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.

Adenocarcinoma, Clear Cell↗
PubMed1995

The tumor suppressor maspin does not undergo the stressed to relaxed transition or inhibit trypsin-like serine proteases. Evidence that maspin is not a protease inhibitory serpin.

The role of tumor suppressor proteins in the development of malignancy has made the understanding of their molecular mechanisms of action of great importance. Maspin is a tumor suppressor produced by a number of cell types of epithelial origin. Exogenous recombinant maspin has been shown to block the growth, motility, and invasiveness of breast tumor cell lines in vitro and in vivo. Although belonging to the the serine proteinase inhibitor (serpin) superfamily of proteins, the molecular mechanism of maspin is currently unknown. Here we show that the reactive site loop of maspin exists in an exposed conformation that does not require activation by cofactors. The reactive site loop of maspin, however, does not act as an inhibitor of proteinases such as chymotrypsin, elastase, plasmin, thrombin, and trypsin but rather as a substrate. Maspin is also unable to inhibit tissue and urokinase type plasminogen activators. Stability studies show that maspin cannot undergo the stressed-relaxed transition typical of proteinase-inhibitory serpins, and the protein is capable of spontaneous polymerization induced by changes in pH. It is likely, therefore, that maspin is structurally more closely related to ovalbumin and angiotensinogen, and its tumor suppressor activity is independent of a latent or intrinsic trypsin-like serine proteinase-inhibitory activity.

Amino Acid Sequence↗