TUMOR-GROWTH AND MELANOGENESIS IN HAMSTER TUMORS INVIVO AND INVITRO - GROWTH, CYTOCHEMISTRY AND ULTRASTRUCTURE OF TISSUE-CULTURE CELL LINES

  • 1 January 1976
    • journal article
    • research article
    • Vol. 11  (1) , 27-37
Abstract
Cell lines were established from 3 hamster melanomas. One was a spontaneous melanotic tumor which lost its ability to produce pigment. Two were induced with DMBA (9,10-dimethyl 1,2-benz(a)anthracene). One of these was pigmented. The 2 amelanotic lines (CHT-1 and 2) produced highly malignant amelanotic tumors after reimplantation of tissue culture cells. EM showed that melanin forming organelles were absent. Tyrosinase activity was also absent. The line established from the pigmented tumor (CHT-8) retained its pigment production for the first 8 transfers. Cells from these cultures produced slow growing pigmented tumors. Cells from the 7th to the 35th transfer, a period of 28 wk, failed to produce tumors but cells from the 36th and subsequent transfers produced slow growing amelanotic tumors. The change in tumorigenicity was not related to changes in the growth rate of the cells in vitro: this remained constant after the 11th transfer generation. Tyrosinase activity and a whole range of melanin forming organelles were present in cells of transfers 1-7 but absent from subsequent transfers. Type A and H virus particles were present in the 2 amelanotic cell lines, CHT-1 and 2. Although the 2 amelanotic lines produced highly malignant tumors the loss of a differentiated character, melanin production, was not invariably associated with increased malignancy. The 3 cell lines should provide a good system for studying the relationship between tumor differentiation and growth.

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