INVITRO TRANSFORMATION OF SYRIAN-HAMSTER EPIDERMAL-CELLS BY "N-METHYLN'-NITRO-N-NITROSOGUANIDINE

  • 1 January 1981
    • journal article
    • research article
    • Vol. 41  (5) , 1669-1676
Abstract
The selection of Syrian hamster epidermal cells which do not terminally differentiate has provided a quantitative focus assay for in vitro chemical transformation. One day old Syrian hamster epidermal cells plated at 5 .times. 106/100 mm dish were treated for 5 h with various concentrations of N-methyl-N''-nitro-N-nitrosoguanidine. After 4 wk, the normal epidermal cells began to terminally differentiate to keratinized squamous cells and died, but transformed epidermal colonies grew to higher cell densities and appeared as darker areas against a lightly stained normal cell background. Transformed epidermal foci were isolated and subcultured for at least 15 passages, whereas normal epidermal cells could not be subcultured under the same conditions. The transformed cells assumed the typical cobblestone-like morphology of epithelial cells, retained desmosomes and tonofilaments, and were able to use citrulline in place of arginine. Argininosuccinate synthetase (EC 6.3.4.5) activity was significantly higher in the epidermal cells than in fibroblasts. The injection of 5 .times. 106 cells of 2 transformed epidermal cell lines into nude mice resulted in the formation of tumors which were identified as keratinizing squamous carcinomas.

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