In Vitro Effects of Irradiation Combined with Actinomycin D

Publisher Website
Google Scholar
Abstract
Investigators in recent years have cited the combined effects of drug therapy and irradiation (1). D'Angio et at. have reported on the potentiation of x-ray effects by actinomycin D in mice and patients. They mention, however, that clinically it is difficult to assess the synergistic action because of varying responses of individuals and histologically similar tumors (2). Cobb studied the effect of actinomycin D on tissue cultures without irradiation (3). The purpose of this communication is to confirm the additive effects of actinomycin D and x-rays in vitro and furthermore to propose a method for the study of such in vitro effects as a means of primary screening. Method The first part of the experiment consisted of an investigation of the growth of HeLa cells on cover-glasses and the effect of the drug and radiation upon them. Six coverglasses, 10 × 50 mm., were mounted with plasma clot on one of the flat surfaces of an S-ounce Neutraglas screw-cap bottle. Fifteen milliliters of LAH medium with 10 per cent Bovine serum containing one million HeLa cells were introduced into each bottle. Twenty-four hours later, a monolayer growth of HeLa cells was observed on the coverglasses. Actinomycin D was added in a concentration of 0.001 μg. per ml. The qualities of radiation used were 2.2 mm. Cu h.v.l. with the 240-kv machine and the electron beam of the betatron at a 21-Mev energy level. On the basis of the treatment received, the material was divided into groups: (a) controls; (b) irradiated with the 200-r electron beam at 21 Mev; (c) irradiated with 200 r with the 240-kv machine; (d) treated with actinomycin D; (e) treated with actinomycin D plus 200 r with the electron beam; (f) treated with actinomycin D plus 200 r with the 240-kv machine. After being exposed once to the radiations, the cover-glasses were observed daily for seven days. Every day one of the coverglasses was removed, fixed, and stained with H and E stains. Significant qualitative and quantitative changes were recorded (Figs. 1–3). The second part of the experiment was concerned with protein determinations, proposed by Oyama and Eagle (4) and Smith et al. (5) as an index of quantitative cellular growth. A suspension of HeLa cells containing 50,000 cells per milliliter was prepared in the usual fashion and was placed in plastic containers, 6 × 3 × 2 cm., made by Falcon Plastic Company. The total culture medium and cell volume was 5 c.c. per container. The groups were similar to those listed above, but no coverslips were used. After exposure to each quality of radiation, the protein content of each container was determined at twenty-four and seventy-two hours. Results Evidence for the potentiating effect of actinomycin D on x-rays was seen in both parts of the experiment.

This publication has 0 references indexed in Scilit: