Unique loss of heterozygosity of murine thymic lymphomas as a candidate of radiation signature

Signature(s) of prior exposure to carcinogens have immediate application to the identification of environmental risk factors. Such signatures have been sought to aid in developing policies for the protection from risks of environmental carcinogens. Although ionizing radiation is a potent carcinogenic agent, little is known about possible radiation signatures. This is because radiation induces a broad spectrum of DNA lesions. Here we describe a diversity of K-ras mutations and a unique locus with frequent loss of heterozygisity (LOH) on chromosome 11 of radiation induced thymic lymphomas. The latter locus has never been observed to be similarly altered in either ethylnitrosourea-induced or spontaneously developed lymphomas. These results describe, to our knowledge for the first time, a molecular basis for radiation signature. (author)