Irisin is the reason that exercise protects against cancer

The best non-medical cancer therapy is exercise, but we don’t know exactly how exercise protects against cancer. Molecular biologists at the University of New Mexico will soon publish in the International Journal of Cancer the results of a fundamental study that should change this situation.

Cancer and exercise

Cellulite occurs when fat in the subcutaneous layers develops a grainy structure. This can happen when the compartments of which fat tissue is composed – researchers call this subcutaneous tissue fascicles – become enlarged.

Studies have shown that there are non-medical anti-cancer strategies that work, and the most effective of these is physical exercise. It doesn’t matter really what your favourite kind of exercise is as long as you do lots of it and often. The more, the better. For an overview of our posts on the cancer-inhibiting qualities of physical exercise go to the bottom of this page.

Exactly how physical exercise messes up cancer cells’ lives is not really known, but scientists have put forward a few theories. One of these is that during exertion muscle tissue secretes anti-cancer substances. These are called myokines, and one of the most studied ones of these is irisin [see right]. Irisin is found in the body in several forms: a non-active form that is secreted by the muscles [IM] and an active form that is created from the inactive form [INM].


Researchers at the University of New Mexico wondered whether irisin could explain why exercise reduces the chance of developing cancer or the disease returning. To answer this question they exposed aggressive MDA-MB-231 breast cancer cells to active and non-active irisin. And hey presto: active irisin reduced the vitality of the cancer cells. Some of the cells self destructed.


In addition, both forms of irisin reduced the ability of the cancer cells to spread.


In another experiment the researchers exposed the cancer cells to a mix of active irisin and the cancer medicine doxorubicin. Irisin made the cancer cells more vulnerable to the medicine.



“Exercise has been shown to result in reduced cancer risk and improved prognosis of cancer patients”, the researchers write. “Our data provides possible insights into potential mechanisms underlying these observations. Moreover, our data supports the hypothesis that irisin may play an important role in future cancer therapeutics, warranting the need for further investigation.”

Effects of the exercise-inducible myokine irisin on malignant and non-malignant breast epithelial cell behavior in vitro.


Exercise has been shown to reduce risk and improve prognosis of several types of cancers. Irisin is a myokine linked to exercise and lean body mass, which is thought to favorably alter metabolism systemically, potentially providing benefit for metabolic disease (including cancer). We evaluated the effects of various concentrations of irisin (with and without post-translational modifications) on malignant and non-malignant breast epithelial cell number, migration and viability. Irisin significantly decreased cell number, migration and viability in malignant MDA-MB-231 cells, without affecting non-malignant MCF-10a cells. Moreover, irisin enhanced the cytotoxic effect of doxorubicin (Dox) when added to a wide spectrum of irisin concentrations in the malignant cell type (with simultaneous reduction in Dox uptake), which was not observed in non-malignant MCF-10a cells. Additionally, we found that irisin decreases malignant cell viability in part through stimulation of caspase activity leading to apoptotic death. Interestingly, we found that irisin suppresses NF?B activation, an opposite effect of other myokines such as tumor necrosis factor alpha (TNF-?). Our observations suggest that irisin may offer therapeutic benefits for breast cancer prevention and treatment possibly through an anti-inflammatory response, induction of apoptotic cell death, or through enhanced tumor sensitivity to common antineoplastic agents such as Dox.

PMID: 25124080 [PubMed – as supplied by publisher]