Chelsea Goodenough, HBSc

Breast cancer is the most common type of cancer that kills women world-wide [1]. Emerging out from under the emotional and financial burden of this disease is the united front of patients, families and researchers alike seeking to understand the complexity of this disease. With exercise's noted benefit to a 30-40% reduction in breast cancer risk, investigation into mechanisms that may be attributing to these findings have unveiled a frontrunner - microRNA. MicroRNA are small non-coding proteins that have the ability to affect what proteins are made by our body. They do this by attaching themselves to their larger counterparts, messenger RNA (mRNA) which code for proteins made in our body. While attached, they act as synthesis promoters or inhibitors of certain proteins. Breast cancer researchers believe that microRNA circulating in the body may seek out the messenger RNA coding for breast cancer promoter proteins, bind to them and halt their production. This would ultimately lead to protein reduction and thusly reduced size and proliferation of tumor cells. But how could these microRNA be related to exercise? Muscles. Our muscles are known as potent reservoirs of these microRNA and it may be possible for exercise to release them into our blood stream. During exercise, our muscles contract and release factors termed "myokines" into circulation that have demonstrated ability to alter signaling pathways associated with muscle health, which is compromised in cancer patients [2-6]. Micro RNA may now fall under the myokine umbrella. It is the hope that continual effort into connecting the inner working of breast cancer cells to a conserved muscle microRNA may provide a mechanistic basis for the benefits of exercise for breast cancer patients. Technologies and laboratory techniques that allow scientists to globally profile circulating microRNA against known cancer proteins is one of the first steps to establishing this connection. As such, the united front of women, families, and researchers continues to work towards understanding the complexity of breast cancer, with microRNA front and center.

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3. Pederson, B., Exercise-induced myokines and their role in chronic diseases. Brain Behaviour Immunology, 2011. 25: p. 811-816.

4. Munoz, R.M., et al., Isolation and Characterization of Muscle Fatigue Substance with Anti-Tumor Activities. Journal of Cancer, 2013. 4(4): p. 343-349.

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6. Aoi, W., et al., A novel myokine, secreted protein acidic and rich in cysteine (SPARC), suppresses colon tumorigenesis via regular exercise. Gut, 2012. 62: p. 882-889.