The stratum corneum chymotryptic enzyme that mediates shedding and desquamation of skin cells is highly overexpressed in ovarian tumor cells

BACKGROUND Proteases play essential roles in the process of tumor invasion and metastasis. The serine protease stratum corneum chymotryptic enzyme (SCCE) has been purified from human stratum corneum and is known to contribute to the cell shedding process by catalyzing the degradation of intercellular cohesive structures at the skin surface. The presence of SCCE on the surface of tumor cells suggests it also may contribute to the process of tumor cell shedding, resulting in early metastasis of carcinoma. METHODS Gene expression of SCCE was investigated in 44 ovarian tumors (12 low malignant potential tumors and 32 carcinomas) and 10 normal ovaries by quantitative polymerase chain reaction (PCR). The PCR product was labeled with 32P and a phosphoimager was used to determine the relative expression of SCCE compared with an internal control B‐tubulin. mRNA transcripts were studied by Northern blot hybridization and protein expression and localization was examined by Western blot analysis and immunohistochemistry. RESULTS mRNA expression levels of SCCE were elevated significantly in 66.7% of 12 low malignant potential tumors and 78.1% of 32 carcinomas. Furthermore, SCCE protein was abundant in tumor cells and tumor cell lines that overexpressed the mRNA transcript. CONCLUSIONS The results of the current study suggest that SCCE frequently is overexpressed in ovarian tumors and therefore may contribute to tumor cell growth, tumor spread, and the metastatic potential of ovarian tumor cells. Cancer 1999;86:2074–82. © 1999 American Cancer Society. The serine protease stratum corneum chymotryptic enzyme, which is expressed abundantly in mature keratinocytes and is responsible for the shedding of these skin cells, is reactivated in transformed ovarian epithelial cells.