BASAL-CELL CARCINOMAS AND SQUAMOUS-CELL CARCINOMAS OF HUMAN SKIN SHOWDISTINCT PATTERNS OF CHROMOSOME LOSS

Although basal cell carcinomas and squamous cell carcinomas are clinic ally and pathologically distinct, the molecular basis for these differ ences is not clear. We have used polymorphic microsatellite markers to determine the pattern and extent of chromosome losses in a series of 44 basal cell carcinomas and 47 squamous cell neoplasms of the skin. B asal cell carcinomas showed a distinctive allelotype with chromosome l oss largely confined to a single chromosome arm, 9q (26 of 44 informat ive tumors). In contrast to the predominance of loss on a single chrom osome arm in basal cell carcinomas, squamous cell neoplasms showed mor e widespread loss with loss of heterozygosity of markers from 35 of 39 chromosome arms in one or more of the tumors studied. The pattern of loss was also different from basal cell carcinomas with frequent loss of heterozygosity of markers from 9p (41%), 139 (46%), 17p (33%), 17q (33%), and 3p (23%) in squamous cell neoplasms. The frequent loss of m arkers from these chromosome arms relative to other chromosome losses suggests that these arms may contain genes important in the developmen t of cutaneous squamous cell carcinomas.