Study of cell kinetics in anaplastic thyroid carcinoma transplanted to nude mice

The cell kinetics of the transplantable human anaplastic thyroid carcinoma were studied in athymic nude mice using bromodeoxyuridine (BrdU) pulse labeling. In order to estimate the cell cycle time in this study, the percent labeled mitosis curve was prepared with immunoperoxidase staining using monoclonal antibody to BrdU instead of 3[H]thymidine autoradiography. This technique was considered to be very useful because it can be done for a short term and can still be changed to the autoradiographic method. Comparing the results in this study with already reported data on various xenografts of human carcinomas in nude mice, the tumor doubling time (117.5 hr) and the cell cycle time (23.5 hr) were rather short, but the growth fraction (54%) and the cell loss factor (68%) were nearly equivalent to the median value. These findings suggest that the very rapid growth rate of this tumor was mainly due to the shortness of the cell cycle time.