Mutation of RAS oncogene in atomic bomb radiation-exposed leukemia.

To determine what the role of RAS oncogene is in radiation-induced leukemia, we investigated the frequency of mutations and the sites of the base substitution of activated N- and K-RAS oncogenes in 25 leukemic patients who had been exposed to the atomic bomb and compared the results with those for 47 non-exposed leukemic patients. To detect the presence of mutated RAS oncogene, we used the PCR method to analyze DNAs from leukemic cells and from nude mouse tumors formed by in vivo selection assay. Eight of the 25 exposed leukemic patients (32%) and 13 of the 47 non-exposed leukemic patients (27.6%) had RAS oncogene mutations. No significant differences were found between the exposed and non-exposed groups in frequency of mutation and the sites of base substitution on the RAS oncogene sequence. This study should prove valuable for understanding the role of RAS oncogene mutation in the genesis of radiation-induced leukemias.