EXERCISE SLOWS CANCER GROWTH.

There is a new benefit of exercise: mice who spent their free time on a running wheel were better able to shrink tumors (a 50% reduction in tumor size) compared to their less active counterparts. Researchers found that the surge of adrenaline that comes with a high-intensity workout helped to move cancer-killing immune (NK) cells toward lung, liver, or skin tumors implanted into the mice. "It is known that infiltration of natural killer (NK) immune cells can control and regulate the size of tumors, but nobody had looked at how exercise regulates the system," says senior study author Pernille Hojman, at the University of Copenhagen. "In our experiments, we tried to inject our mice with adrenaline to mimic this increase you see during exercise, and when we do that we see that the NK cells are mobilized to the bloodstream, and if there's a tumor present then the NK cells will find the tumor and home to it." "It is known that infiltration of natural killer (NK) immune cells can control and regulate the size of tumors, but nobody had looked at how exercise regulates the system," says senior study author Pernille Hojman, at the . "In our experiments, we tried to inject our mice with adrenaline to mimic this increase you see during exercise, and when we do that we see that the NK cells are mobilized to the bloodstream, and if there's a tumor present then the NK cells will find the tumor and home to it." The research group also discovered that an immune signaling molecule called IL-6 was the link between adrenaline-dependent mobilization of NK cells and tumor infiltration. It's known that IL-6 is released from muscle tissue during exercise, but Hojman presents evidence that adrenaline specifically aids IL-6 sensitive NK cells and that the IL-6 molecules helped guide the immune cells to the tumors. "That was actually a big surprise to us," she says, adding that IL-6 and its role in tumor biology can be a controversial topic. "In this study we show that the exercise-induced IL-6 seems to play a role in homing of NK cells to the tumor and also in the activation of those NK cells." This study appears Feb. 16, 2016 in Cell Metabolism, excerpts culled from science daily.