Integrins and basement membrane proteins in skin carcinomas

The topography of some integrins and basement membrane proteins in cutaneous basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) has been studied by immunohistochemistry. The typical cell-to-cell distribution of α2β1 and α3β1 of normal epidermis becomes pericellular in both BCC and SCC cells. BCC and SCC also showed different patterns of expression of α6β4, the integrin normally located at the basal surface of basal epidermal keratinocytes. SCC showed high expression and pericellular distribution of α6β4, while BCC did not express α6β4 at all also in Western blotting. The basement membrane was markedly different in the two tumor types. Laminin and collagen type IV were conserved in the basement membrane zone of both tumors while nicein/kalinin was absent from BCC cells. The simultaneous loss of expression of α6β4 and nicein/kalinin in BCC cells but not in SCC cells indicates that α6β4 and one potential ligand may be co-regulated in both BCC and SCC. We suggest a role for this phenomenon in the pathogenesis of these epidermal tumors.