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 t ransformation by 6 MeV alpha particles and Cs-137 gamma rays in REC:my c and REC:ras cells, that is, rat embryo cells (REC) transfected with the c-myc or the Ha-ras oncogenes. The 6 MeV particles simulated Rn-22 2 emissions for risk assessment relative to low-LET radiations. The do se of gamma rays was approximately twice that of alpha particles for a neoplastic transformation frequency of 10(-3). The survival of the RE C cells containing oncogenes was comparable to that of the commonly us ed C3H 10T1/2 cells for the same dose, but the former were more refrac tory to radiation-induced neoplastic transformation. Neoplastic transf ormation frequency measured in REC cells was 3 times lower than those typically measured in C3H 10T1/2 cells at a gamma-ray dose of 6 Gy, an d 5-10 times lower at an alpha-particle dose of 3 Gy.