Attenuation of the development of murine solid leukemia tumor by physical exercise

The active involvement of physical exercise in the evolution of a variety of cancers is well documented. However, its role in solid leukemia tumor development is essentially unknown. Solid leukemia tumor cells were transplanted into 21 hybrid BDF1 control mice, exercise-trained mice that did not exercise during leukemia and exercise-trained mice that exercised during leukemia. The tumor size of the continuously exercising group was ~50% of that of control and exercise-terminated animals 18 days after the transplantation. The activity of antioxidant enzymes and the levels of lipid peroxidation and 8-hydroxy-2'-deoxyguanosine were not different in the tumors of the three groups. The level of carbonylated proteins was smaller in tumors of continuously exercising animals. The mutant form of cell regulatory protein p53 and vascular endothelial growth factor were present in similar amounts in the tumor cells of each group. On the other hand, the protooncogene Ras and I-kappaB proteins were present in higher concentrations in tumors of continuously exercising rats. The present data suggest that exercise during leukemia attenuates the development of tumors in mice. The selective alteration of regulatory proteins might play a role in the beneficial effects of exercise during leukemia.