Differences in effects of oncogenes on resistance of gamma rays, ultraviolet light, and heat shock.

The effects of viral or activated cellular oncogenes on sensitivity to gamma rays, ultraviolet light, and heat shock were examined in SHOK (Syrian hamster Osaka-Kanazawa) cells and their transfectants. Resistance to gamma rays was conferred by the introduction of v-mos or c-cot genes, which coded serine/threonine kinase. Cells transfected with v-mos and c-cot genes increased their resistance to ultraviolet light and heat shock compared to their parent cells (SHOK cells). Of the activated ras genes, the N-ras gene developed a SHOK cell phenotype resistant to gamma rays and ultraviolet light. The Ha-ras gene produced SHOK cells resistant to ultraviolet light and heat shock, while introduction of the Ki-ras gene did not affect sensitivity. The v-erbB gene was found to be involved in the development of resistance to heat shock. Transfection with neo, c-myc, and v-fgr genes had little or no effect on cell survival. The karyotypes of SHOK cells and oncogene-containing cells were compared. No alterations were seen after the introduction of a foreign gene. Using cell cycle analysis, we found no apparent difference between SHOK cells and their transfectants. These results suggest that activation of serine/threonine kinase may be involved in common processes occurring after gamma-ray, ultraviolet-light, and heat-shock treatment, and that each oncogene may have a different effect on the development of a resistant phenotype.