ESTIMATION OF TUMOR SENSITIVITY IN VITRO .I. COMPARATIVE STUDIES WITH JENSEN SARCOMA IN VIVO AND IN VITRO AFTER 1-HOUR-INCUBATION

In a first series of experiments concerning testing of the sensitivity of tumors in vitro, small pieces of fresh isolated Jensen-sarcoma were incubated with the following drugs: Actinomycin C, Rubidomycin, N-Mustard, Triaziquon, Amethopterin, 5-Fluorouracil, Colcemid, and Vinblastin. In order to study the nucleic acid metabolism, the incubation medium contained 3H-thymidine for DNA and 3H-cytidine or 3H-uridine for RNA. In parallel experiments the action of these drugs on tumor growth in vivo was studied. The amount of radioactive material incorporated was evaluated by means of autoradiography and measured by the liquidscintillation technique. The results were expressed in per cent of controls without cytostatic agent. The effects observed corresponded well with the biochemical mode of action of each drug. The importance of a knowledge of the specific mode of action is discussed taking as example the increased incorporation of 3H-thymidine using Amethopterin and 5-Fluorouracil. A comparison of the results of the experiments in vivo and in vitro shows a certain correlationship between depression of RNA synthesis in vitro and retardation of tumor growth by the same drug in vivo. Further investigations with tumors of different sensitivity are needed. © 1969 Springer-Verlag.