Persistent inhibition of DNA synthesis after radiation exposure in four clones obtained from rat embryo fibroblasts by transfection with the oncogenes H-ras plus v-myc.

We have previously shown that two cell lines, 2.8 and 3.7, obtained from rat embryo fibroblasts (REF) by transfection with the oncogenes, H-ras plus v-myc, experience a prolonged inhibition of DNA replication after exposure to ionizing radiation as compared with normal REF, or REF expressing, H-ras or v-myc alone. We report here that four additional cell lines generated in our laboratory by cotransfection of REF with the same oncogenes also show prolonged inhibition of DNA replication after radiation exposure. These results indicate a regulatory mechanism for DNA replication in irradiated REF in which the products of the oncogenes H-ras and v-myc have a central role.