Establishment of a human cancer cell line from carcinoma of the gingiva.

A new human epithelial cell line (MK-1) has been established from a well differentiated squamous cell carcinoma of the gingiva. It has been subcultured 90 times during the past 23 months. The population doubling time of the MK-1 cell line was 28 h. A colony forming ability with 18% plating efficiency was shown. Chromosomal analysis revealed an aneuploid human male karyotype with 22 marker chromosomes. The model chromosome number was 75. Scanning electron micrographs of MK-1 cells showed numerous microvilli and intercellular bridges. Transmission electron micrographs of MK-1 cells showed epithelial characteristics with desmosomes, tonofilaments and membrane-coating granules. Hetero-transplantation of cultured MK-1 cells produced tumors, the histology of which was similar to that of original ones. The ultrastructure of the tumors showed the presence of abundant tonofibrils and keratohyalin granules. This MK-1 cell line is a model useful for the study of keratinization of squamous cell carcinomas.