TRANSFORMATION OF MOUSE C3H-10T1-2 CELLS BY SINGLE AND FRACTIONATED DOSES OF X-RAYS AND FISSION-SPECTRUM NEUTRONS

Abstract

A mouse embryo-derived cell line, C3H/10T1/2, was used to measure the frequency of in vitro neoplastic transformation induced by 50 kVp X-rays and by fission-spectrum neutrons from the JANUS reactor at the Argonne National Laboratory. The transformation frequency after single X-ray doses rises exponentially, reaching a plateau at about 3 .times. 10-3 transformant/survivor. The induction curve following single neutron doses, while qualitatively similar, initially rises more steeply and levels off at a maximum of about 6 .times. 10-3 transformant/survivor. For both radiations, transformation frequency varies with changes in the number of viable cells per dish, showing about a 10-fold decrease in transformation frequency when the number of viable cells per 90 mm dish was increased from 300 to about 1000. Fractionation of a total X-ray dose of 700 rad results in an approximately 6-fold increase in survival and reduction in transformation frequency over a 16 h interval. Fractionation of the total neutron dose of 378 rad has no effect upon cell survival, and transformation frequency declines by a factor of only about 1.7 at most over a 24 h period. Cells derived from transformed foci formed fibrosarcomas when injected into appropriately treated mice.