DIFFERENTIAL EXPRESSION OF SKALP ELAFIN IN HUMAN EPIDERMAL TUMORS

Recently we described a new epidermal serine proteinase inhibitor, ski n-derived antileukoproteinase (SKALP), also known as elafin. SKALP/ela fin was found to be absent in normal human epidermis, but can be induc ed in vitro and in vivo under hyperproliferative conditions. Here we s tudied the expression of SKALP/elafin in several types of epidermal tu mors (basal cell carcinoma, squamous cell carcinoma, Bowen's disease, actinic keratosis, and keratoacanthoma). Using immunohistochemical sta ining SKALP/elafin appeared to be differentially expressed in these tu mors. Functional measurements of anti-proteinase activity, and Western blotting of tumor extracts confirmed our findings at the histological level In well differentiated squamous cell carcinoma, SKALP/elafin me ssenger RNA was demonstrated by non-radioactive in situ hybridization. We conclude that SKALP/elafin is a marker for abnormal or disturbed s quamous differentiation. A possible role of SKALP/elafin in the contro l of tumor cell invasion is discussed.