Involvement of oncogenes in radon-induced lung tumors in rats

Several oncogenes, notably those of the ras and myc family, have been implicated in the induction of lung tumors. Although inhalation of radon and radon daughters has been shown to result in a high incidence of lung tumors, the role of oncogenes in these tumors (if any) remains unknown. In certain cases of chemically induced carcinogenesis, unique point mutations in the 12th, 59th, and 61st codons of H-ras and Ki-ras have been found to transform ras proto-oncogenes to dominant-acting oncogenes. We have isolated DNA from fixed, archived, radon-induced tumors in rats, amplified the oncogene of interest by polymerase chain reaction, and analyzed it by sequencing. Although we have not found any of the classically described point mutations in the H-ras gene, preliminary evidence indicates that several common mutations occur with high frequency in the second exon. These point mutations have not been seen in any open-quotes spontaneouslyclose quotes occurring tumors. At present we theorize that these mutations represent one of the secondary effects of a multi-step process in the development of these lung tumors. As this project expands, we are making a systematic effort to correlate the molecular data with the pathological data derived from the original studies of these archived tumors