Voluntary exercise suppresses tumor growth through exercise-directed recruitment and intratumoral infiltration of NK cells. Mus musculus

Voluntary exercise reduces the risk of cancer and lowers the risk of disease recurrence. Yet the mechanisms for this protection remain to be elucidated. Here we demonstrate that exercise halves tumor growth through an exercise-dependent mobilization and intratumoral infiltration of NK cells in malignant melanoma. Using voluntary wheel running, we show that exercise prior to and during B16 tumor challenge reduced tumor growth by 67%, and this reduction was associated with increased inflammation and immune cell infiltrates, especially NK cells, in the tumors from exercising mice. Depletion of NK cells blunted the exercise-dependent reduction in tumor growth. Moreover, during exercise, NK cells were engaged through an epinephrine-dependent mobilization to the circulation and redistributed to peripheral tissues through an IL-6 dependent mechanism. This study highlights the importance of exercise-dependent immune regulation in the control of malignant melanoma Overall design: Gene expression profile of melanoma tumor tissue from two groups of exercise and non-exercise mice