Filamentous protein of basal cell epithelioma: characteristics in vivo and in vitro.

The sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) pattern of the citrate-soluble fibrous protein isolated from human basal cell epitheliomas showed polypeptides with molecular weights of 43,000, 45,000, and 59,000. These polypeptides, found in the protein of normal epidermis, were present in a different proportion in this tumor tissue. Basal cell epitheliomas were cultured by the use of killed murine 3T3 feeder layers but only when 10(-9) M cholera toxin was present. The SDS-PAGE pattern of fibrous protein from cultured tumor cells was identical to the pattern of cultured normal human epidermal cells, and cornified cell envelopes were found in both types of cultures. Electron microscopy showed stratified cells that contained desmosomes, tonofilaments, and keratohyalin granules.