Correlation of prekaratin peptides and ultrastructure in epithelial cells of human skin tumors in vivo and in vitro.

Prekeratin was reduced in human skin malignancies comparing Bowen's carcinoma (BC), basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) with normal epidermis. This observation correlated with ultrastructural appearance and frequency of tonofilaments. Gel electrophoresis of tumor extracts revealed the decrease or loss of larger prekeratin peptides (65 to 68 K daltons) prominent in the epidermis. Biopsies, particularly from BC, resembled normal keratinocytes in culture with respect to their prekeratin patterns (48 to 61 K daltons). The pattern was most different, and prekeratin lowest, in SCC and derived cultures. In BCC-cultures, however, prekeratin (almost identical to keratinocytes) and filament formation significantly exceeded the respective tumor levels.