Examination of the 75Se-affinity of the tumor cells, changes under the effect of radiation

The NaSeO3 accumulates in the tumor tissue. Authors examined this characteristic of 75Se-labelled sodium selenite in irradiated Ehrlich ascites carcinoma and Guerin carcinoma. The activity of the protein fraction insoluble in hot trichloroacetic acid was determined in the tumor cells after local X-irradiation (1750 R) and after i.p. and i.v. administration of 5-20 μCi of radioactive sodium selenite. Chromatography of the preparates was also performed. While in the control liver preparates the incorporation of selenium only slightly decreased as a result of irradiation, in Ehrlich ascites tumor cells the incorporation was only 71% and in Guerin tumor cells 63% of the corresponding values without irradiation. The chromatography showed that the mechanisms regulating the incorporation of the sodium selenite into the proteins change as a result of the radiation effect. Thus, according to the results, the radiation therapy influences the protein metabolism of the tumor cells, in a considerably smaller dose than it has been supposed yet. (U.E.)