Muscle Contraction Arrests Tumor Growth
Final rept. 1 Sep 2005-31 Aug 2007
COLORADO UNIV HEALTH SCIENCES CENTER AURORA CO
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We examined the hypothesis that a fatigue factors is released by contracting muscle resulting in tumor inhibition. We used extracts from hind leg muscles stimulated STIM with moderate intensity to evaluate effects MCF7 and MDA MB 231 cells. The extracts were tested in vitro using 5-bromo-2-deoxyuridine incorporation and an apoptosis index based on morphology. STIM extracts increased apoptosis 127 MCF7 and 190 MDA MB 231 p 0.05 compared to SHAM, but had no effect on proliferation. No difference in effect was observed between cell lines. Based on the in vitro results, extracts were injected subcutaneously into female nude mice transplanted with breast tumor cells. Injections were daily for 4 weeks. Tumor size was measured 2xwk and animals sacrificed after 4 wks. Tumors were excised, weighed and analyzed to determine proliferation and apoptotic indices. Tumors in animals treated with STIM extracts were significantly smaller 172 51mm3 than the SHAM 336 49mm3 and had increased apoptosis, by morphology and by TUNEL assay p 0.03. It appears that muscle contraction releases a factor which increased tumor cell apoptosis and caused smaller slower growing tumors. This may be one of the mechanisms by which exercise inhibits breast cancer development.
- Medicine and Medical Research