CELL-TYPE RELATED AND SPATIAL VARIATION IN THE EXPRESSION OF INTEGRINS IN CUTANEOUS TUMORS

Integrins constitute a group of transmembrane proteins which mediate c ell-cell and cell-matrix interactions. Previous studies have shown bot h increased and decreased expression of integrins in relation to malig nancy and invasion. In the present study, we investigated integrin dis tribution in cutaneous tumors by using monoclonal antibodies on frozen tissue sections. Antibodies to integrin subunits alpha nu, alpha 3, a lpha 4, alpha 5, alpha 6, beta 1 and beta 3 were used. The study was d esigned to explore (i) the association between integrin expression and the tumor type, and (ii) the effect on the integrin expression of the location of the tumor, i.e. whether it grows intraepidermally or with in various compartments of the dermis (papillary or reticular). beta 1 , beta 3 and alpha 3 were strongly or moderately expressed in the epit helial and stromal cells of basal cell carcinomas (BCC), seborrheic ke ratoses, solar keratoses, dermatofibromas (DF), and showed a variable expression in the nevic cells of benign and dysplastic nevocellular ne vi. alpha nu and in alpha 5 appeared strongly expressed in the stromal cells of BCC and DF, while only a focal, often weak staining was seen in nevic cells and in the epithelial cells of BCCs. In some nevocellu lar nevi, they were only expressed, together with alpha 4, in the deep -seated nevic cells in the reticular dermis. alpha 6 was expressed by tumor cells of BCCs and nevocellular nevi only within the dermo-epider mal junction. In seborrheic keratosis and solar keratosis a basement m embrane-associated staining pattern for alpha 6 was seen in the basal cell layer, with focal discontinuities in solar keratosis. In conclusi on, the results indicate a wide expression of various types of integri ns in cutaneous tumors. The expression is distinctly tumor-type and ce ll-type dependent but is also influenced e.g. by the depth of the stro mal infiltration in BCC (alpha 6) and in nevocellular tumors (alpha nu , 4, 5, 6, beta 3), probably reflecting adaptation to the variable mic roenvironmental influences.