抄録
C3H/He mice develop acute myeloid leukemia (AML) after whole-body irradiation, and typical chromosome 2 deletions are found in the leukemic cells. While the AML-type deletions are found in the bone marrow cells just after irradiation, the frequency of the individuals bearing the deletions rises after a year or so. These findings have suggested a hypothesis that the AML-type deletions in the primitive stem cells could result from delayed chromosomal aberrations. To test this hypothesis, we have cytogenetically examined primitive hematopoietic cells of irradiated animals. Ten-week male C3H/He mice were exposed to 3Gy x-rays and sacrificed after one or ninety days after irradiation. Bone marrow cells collected from each animal were divided into two batches. One batch was cultured in methylcellulose medium, and metaphase spreads were prepared from each growing colony. The other batch was sorted to obtain Lin+ and Lin-Sca1+ cells, which were analyzed with FISH for the AML-type deletions. Non-clonal aberrations were found in colonies in methylcellulose medium, and its frequency was higher at 90 days after irradiation. However, no aberration has been observed in chromosome 2. FISH analysis of the sorted cells detected AML-type deletions in Lin-Sca1+ subpopulation at one day after irradiation, and the deletions were retained in some individuals even after 90 days. These results do not necessarily support involvement of delayed chromosomal aberrations in radiation-induced AML in mice.
