Comparison of the malignant potential of 10T 1/2 cells and transformants with their survival responses to hyperthermia and to amphotericin B1.

Several responses of 10T 1/2 cells and of cells from strains transformed by X-irradiation or by methylcholanthrene exposure were examined. Malignant potential, as determined by the ability of the cells to initiate tumors in syngeneic hosts, either normal or rendered immunodeficient, varied by a factor of 10(6). The growth rate of tumors both in normal and in irradiated animals was closely correlated to malignant potential. The life spans of the animals were inversely correlated with malignant potential. Serum requirements were high for 10T 1/2 and for one of the X-ray transformants; neither of these cell strains gave rise to tumors when cells were injected into hosts. All malignant strains had uniformly lower serum requirements. While 10T 1/2 cells tended to be somewhat more heat resistant than were any of their transformed counterparts, this depended upon cell density (or state of growth) during heating. There was no correlation between malignant potential and heat sensitivity among the transformed strains. In fact, the most resistant transformant was also the most malignant; furthermore, its heat sensitivity was not modified by growth in vivo. No relationship between malignant potential and response to the polyene antibiotic amphotericin B could be observed.