Cytokeratins in human basal and squamous cell carcinomas: biochemical, immunohistological findings and comparisons with normal epithelia

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Abstract
The nature of human epithelial cell cytokeratins from epidermal basal cell carcinomas (BCC) (8 cases) and squamous cell carcinomas (SCC) (5 cases) was investigated by biochemical and immunological analysis. Cytokeratin proteins were extracted with high salt buffer and triton X 100 and were comparatively analyzed by SDS (sodium dodecyl sulfate) polyacrylamide gel electrophoresis. Both types of tumor showed either an absence or a very low amount (5% of the total protein) of the major protein band (MW 67,000) present in normal human epidermis. This correlated well with results of immunolabeling showing that 67,000 keratin antisera only reacted with some dysteratotic cells in sections of these tumors. Gel electrophoresis showed in BCC and SCC, 3 distinct groups of predominant polypeptide bands of apparent relative MWP: 60-62,000, 54-56,000, and 49,000, representing, respectively, about 43.0%, 31.0% and 20.4% of the total proteins. Antibodies raised in animals against polypeptide bands C1 (MW 62,000), C2 (MW 56,000) and C3 (MW 49,000) from SCC strongly labeled (indirect immunofluoresence) all malignant cells present in the 2 kinds of tumors. These antisera showed a preferential reaction with the basal epithelial cells, in sections of human and animal epidermis and mucosa, suggesting numerous common antigenic determinants between epithelial cells from diverse origins. Strong differences between mucosal and epidermal upper layers were noted with C1, C2, C3 and 67,000 antisera. The results are further evidence for the existence of different pathways of keratinization in epidermis and mucosa.