Trisomy #15 in Murine Thymomas Induced by Chemical Carcinogens, X-Irradiation, and an Endogenous Murine Leukemia Virus2

Abstract

Chromosome banding techniques were used to examine the karyotype of tumor cells from thymic lymphomas induced by three different carcinogens (X-irradiation, polycyclic aromatic hydrocarbons, and an endogenous leukemogenic virus) after injection into neonatal mice of 2 different inbred mouse strains (CFW/D and C57BL/Ka). A total of 89 tumors were studied, and of these 85.4% were characterized by a modal chromosome number of 41. The additional chromosome was the result of a specific abnormality identified as trisomy of chromosome #15. The results obtained were independent of the carcinogenic agents and the strain of mouse used. Of the 13 tumors found to have a normal chromosome complement, 4 were induced by X-Irradiation and the remaining 9 by the chemical carcinogens. All 15 virus-induced tumors analyzed had a modal chromosome number of 41.