Background: Regular physical activity protects against the development of breast and colon cancer, as regular physical activity reduces the risk of developing these with 25-30%. During exercise, humoral factors are released from the working muscles for endocrinal signalling to other organs. We hypothesized that these myokines mediate some of the inhibitory effects of exercise on mammary cancer cell proliferation. Methods and results: Serum and muscles were collected from mice after a bout exercise. Incubation with exercise-conditioned serum inhibited MCF-7 cell proliferation by 52% and increased caspase activity with 54%. Similar increase in caspase activity was found after incubation of MCF-7 cells with conditioned media from electrically stimulated myotubes. PCR array analysis (CAPM-0838E, SABiosciences) revealed that 7 genes were up- regulated in the muscles after exercise, and of these Oncostatin M (OSM) proved to inhibit MCF-7 proliferation by 42%, increase caspase activity by 46% and induce apoptosis. Blocking OSM signalling with anti-OSM antibodies reduced the induction of caspase activity with 51%. To verify that OSM was a myokine, we that OSM was significantly up-regulated in serum and in 3 muscles: tibialis cranialis, gastronemius and soleus after an exercise bout. In contrast, OSM expression remained unchanged in subcutaneous and visceral adipose tissue, liver and spleen (mononuclear cells). Conclusion: Post exercise serum inhibits mammary cancer cell proliferation and induces apoptosis of these cells. We suggest that one or more myokines secreted from working muscles, may be mediating this effect and that OSM is a possible candidate. These findings emphasize that role of physical activity in cancer treatment, showing a direct link between exercise-induced humoral factors and decreased tumor cell growth.
- breast cancer
- physical activity
- anti-cancer effect
- Copyright © 2011, American Journal of Physiology - Endocrinology and Metabolism