Host: The Japan Radiation Research Society
Co-host: City of Kitakyushu, University of Occupational and Environmental Health, Japan
X-ray induces myeloid leukemia in C3H/He mice with the incidence of 20-25% at 3Gy. Mutation of Sfpi1 (PU.1) is crucial in the development of myeloid leukemia. The mutation, however, is mostly specific point mutations in the DNA-binding Ets domain of PU.1, and they are unlikely to be a direct consequence of radiation-induced DNA damage. To elucidate when and how often this type of mutation arises in hematopoietic cells, we have developed a technique that is capable of detecting a small number of mutated cells in the vast majority of non-mutated cells. The technique is based on the wild-type blocking PCR, in which LNA (locked nucleic acid) oligonucleotide blocks amplification of wild-type DNA during PCR while permitting amplification of mutants. The PCR followed by restriction enzyme digestion has enabled to detect mutant DNA in 104 times amount of wild-type DNA. This technique is being applied to DNA samples from C3H/He mice that were exposed to 3Gy of x-rays and were maintained for more than a year. Among 12 exposed mice and 6 age-matched controls analyzed so far, the mutation has been detected in a sample from the spleen of an exposed mouse.
