Neoplastic transformation dose response of oncogene-transfected rat embryo cells by gamma rays or 6 MeV alpha particles

We measured a dose-response relationship for induction of neoplastic transformation by 6 MeV α particles and 137 Cs γ rays in REC:myc and REC:ras cells, that is, rat embryo cells (REC) transfected with the c-myc or the Ha-ras oncogenes. The 6 MeV α particles simulated 222Rn emissions for risk assessment relative to low-LET radiations. The dose of γ rays was approximately twice that of α particles for a neoplastic transformation frequency of 10-3. The survival of the REC cells containing oncogenes was comparable to that of the commonly used C3H 10T1/2 cells for the same dose, but the former were more refractory to radiation-induced neoplastic transformation. Neoplastic transformation frequency measured in REC cells was 3 times lower than those typically measured in C3H 10T1/2 cells at a γ-ray dose of 6 Gy, and 5-10 times lower at an α-particle dose of 3 Gy. 29 refs., 3 figs., 2 tabs