Activity of the proteolytic enzyme guanidinobenzoatase in human basal cell carcinoma

Basal cell carcinomas exhibit a characteristic pattern of aggressive invasion from the basal layer of skin epithelial cells. These tumour cells possess an enzyme, guanidinobenzoatase (GB), which is known to be associated with cell migration. The enzyme is inhibited by a fluorescent probe, 9-aminoacridine, and this can be used to locate cells possessing active guanidinobenzoatase. All basal cell carcinoma cells in frozen sections were located by their ability to bind 9-aminoacridine. Extracts of most tissues were shown to contain inhibitors of the GB associated with basal cell carcinoma cells. Extracts of skin, however, failed to inhibit this tumour-associated GB. The significance of these results is discussed in terms of the pathophysiology of basal cell carcinomas.