EXPRESSION OF TETRA-SPANS TRANSMEMBRANE FAMILY (CD9, CD37, CD53, CD63, CD81 AND CD82) IN NORMAL AND NEOPLASTIC HUMAN KERATINOCYTES - AN ASSOCIATION OF CD9 WITH ALPHA-3-BETA-1 INTEGRIN

Tetra-spans transmembrane family (TSTF) members (CD9, CD37, CD53, CD63 , CD81 and CD82) have potent effects on cell growth, motility and adhe sion in various cells. However, little is known about their expression in human skis, Using immunohistological techniques, we have studied t he localization of all six members of TSTF in normal and carcinomatous human keratinocytes, CD9, CD81 and CD82 were expressed in the entire living layers of the epidermis. Their staining pattern las quite simil ar and Ras mainly intercellular with occasional intracellular immunore activity: CD53 expression was confined to the intercellular spaces of the upper spinous or granular layer in the normal epidermis. No clear- cut express-ion of CD63 could be detected in the epidermis, CD37 was n ot detected at all. Cultured human keratinocytes also expressed CD9, C D81 and CD82 at the surface membrane of cell-cell boundaries, Expressi on of CD37 and CD53 was negative in cultured keratinocytes, while CD63 was clearly localized in the cytoplasmic lysosomes. An immunoprecipit ation assay revealed that alpha 3 beta 1 integrin is molecularly assoc iated with CD9. The expression of CD9, CD81 and CD82 was markedly down -regulated in basal cell carcinoma but not in Bowen's disease, The abu ndant and differential expression of TSTF molecules and the selective association of CD9 with alpha 3 beta 1 integrin suggest that the TSTF molecules may be involved in the regulation of epidermal differentiati on and integrity in vivo.