A small but robust study from researchers at Australia’s Edith Cowan University has discovered one way exercise can help suppress cancer growth. The study found exercise induces muscles to release a type of protein that can slow the growth of tumor cells.
It is no surprise to find a longstanding association between physical activity and lower rates of cancer. And cancer patients who exercise frequently generally have better treatment outcomes than those who don’t, but exactly how exercise can directly fight back against cancer is still unclear.
This new research recruited 10 prostate cancer patients and tasked them with a 12-week exercise program alongside their conventional treatment of androgen deprivation therapy. The 12-week program included a balance of aerobic and muscle-building exercises, and also was accompanied by protein supplements and a calorie-controlled diet. The main focus of the study was to investigate changes in blood myokine levels.
Myokines are proteins released by skeletal muscle cells in response to exercise. They are responsible for a number of healthy body functions and the new research hypothesized the proteins to have tumor suppression capabilities.
Compared to baseline blood tests, the researchers found myokine levels had significantly increased at the end of the 12-week intervention. To investigate whether these heightened myokine levels influenced tumor cells the researchers took the blood samples and applied them to cancer cells in the lab.
“When we took their pre-exercise blood and their post-exercise blood and placed it over living prostate cancer cells, we saw a significant suppression of the growth of those cells from the post-training blood,” says Robert Newton, an author on the new study. “That’s quite substantial indicating chronic exercise creates a cancer suppressive environment in the body.”
While the findings are by no means definitive they certainly offer clues to how exercise can be beneficial, both in preventing the development of cancer and as an adjunct to ongoing cancer therapy. Jin-Soo Kim, lead researcher on the project, says it is important to note myokines do not seem to directly kill cancer cells, so there is no suggestion exercise alone can cure cancer.
“Myokines in and of themselves don’t signal the cells to die,” notes Kim. “But they do signal our immune cells – T-cells – to attack and kill the cancer cells.”
Although the researchers suggest this mechanism should apply to all cancers, the study focused particularly on prostate cancer, a highly common form of the disease. All men in the study were undergoing androgen deprivation therapy to treat their cancer.
When we took their pre-exercise blood and their post-exercise blood and placed it over living prostate cancer cells, we saw a significant suppression of the growth of those cells from the post-training blood
This form of therapy can often result in a condition known as sarcopenic obesity, where a patient loses high volumes of lean muscle mass. The researchers note their findings indicate myokine expression directly correlated with changes in lean muscle mass, affirming the importance of maintaining those muscles during cancer therapies.
“These men have high disease burden, extensive treatment side-effects and are very unwell, but they still can produce anti-cancer medicine from within,” says Newton. “It’s important as it may indicate why men even with advanced cancer, if they’re physically active, don’t succumb as quickly.”
It is likely the myokine findings are just one piece in the larger exercise/cancer puzzle, and plenty more work is needed to better understand how to optimize exercise-induced myokine expression. Newton and colleagues have already started a longer six-month investigation into the influence of exercise on advanced-stage prostate cancer.
The new study was published in Medicine and Science in Sports and Exercise.
Source: Edith Cowan University
