Different sensitivity to actinomycin D of biopsies of human tumors cultivated in vitro

Abstract Primary cultures of 16 human carcinomas, 8 osteogenic sarcomas, 12 sarcomas of different origin have been studied morphologically during the first week of culture. The lethal concentration of actinomycin D after a 24 -hr treatment was established for both the malignant and the normal population of stromal cells. Results indicate that normal cells have a low sensitivity to actinomycin D in a narrow range of doses, while cancer cells show a higher sensitivity in a significantly wider range of doses. In osteogenic sarcomas the L.E. ranged from 0·1 to 100 μg/ml in the different patients.