Molecular alteration of alpha-induced transformed Syrian hamster embryo cells

Syrian hamster embryo (SHE) cells are irradiated by alpha particles emitted from Plutonium-238 in vitro. Transfection frequencies of donor DNA derived from passaged cells, including monocloned cells from 20th passage cells, after irradiation are parallel with their tumorigenicity of donor cells. After transformation, expressions of H-ras and c-myc genes are in the state of activation, which might be resulted from occurrence of mutation in H-ras gene and hypomethylation of c-myc gene respectively, even though no alteration was observed on their restriction fragment length polymorphisms (RELP) patterns of both genes. On the other hand, expression of p53 gene is also found to be in the state of activation in transformant, but no heavy staining of p53 protein appeared in the transformant-derived tumor with p53 specific McAb HD 200. This might be result from the partial deletion of p53 cDNA in transformant by reverse transcriptional polymerase chain reaction (RT-PCR). These results imply that activation of H-ras and c-myc genes coupled with inactivation of p53 tumor suppressor gene play important role in alpha particle-induced cell transformation.