Excerpt from InspireHealth Research Updates – February Edition

Research Updates is published once a month to provide the latest integrative cancer care research to patients, health care providers and the public.  

Each month we present five to six research abstracts and delve into the full text of each article to give you our interpretation. Our goal is to further educate our readers about the many facets of healthy living and provide a thorough, informative, and hopefully educational analysis of each research paper presented.  Below, we have chosen one abstract to feature followed by our interpretation.

February Featured Abstract 

Effect of Acute Exercise on Prostate Cancer Cell Growth

Source: PLoS One. July 2013; 8(7): e67579.
By: Rundqvist, H, M. Augsten, A. Stromberg, et al.

Physical activity is associated with reduced risk of several cancers, including aggressive prostate cancer. The mechanisms mediating the effects are not yet understood; among the candidates are modifications of endogenous hormone levels. Longterm exercise is known to reduce serum levels of growth stimulating hormones. In contrast, the endocrine effects of acute endurance exercise include increased levels of mitogenic factors such as GH and IGF-1. It can be speculated that the elevation of serum growth factors may be detrimental to prostate cancer progression into malignancy. The incentive of the current study is to evaluate the effect of acute exercise serum on prostate cancer cell growth. We designed an exercise intervention where 10 male individuals performed 60 minutes of bicycle exercise at increasing intensity. Serum samples were obtained before (rest serum) and after completed exercise (exercise serum). The established prostate cancer cell line LNCaP was exposed to exercise or rest serum. Exercise serum from 9 out of 10 individuals had a growth inhibitory effect on LNCaP cells. Incubation with pooled exercise serum resulted in a 31% inhibition of LNCaP growth and pre-incubation before subcutaneous injection into SCID mice caused a delay in tumor formation. Serum analyses indicated two possible candidates for the effect; increased levels of IGFBP-1 and reduced levels of EGF. In conclusion, despite the fear of possible detrimental effects of acute exercise serum on tumor cell growth, we show that even the short-term effects seem to add to the overall beneficial influence of exercise on neoplasia.

Our Interpretation

There is evidence that long-term exercise is beneficial for both prevention and progression of prostate cancer. The goal of this study was to evaluate the effects of a single bout of aerobic exercise on the growth of prostate cancer cells. To examine prostate cancer cell growth, an established prostate cancer cell line (LNCaP) was cultured with either 5% resting serum, or 5% post-exercise serum. Though the sample size was small, the results were statistically significant. Exercise serum inhibited growth of LNCaP cells in 9 of 10 subjects, with an average inhibition of 31%.

Additionally, these investigators measured the response of 23 different serum cytokines (small proteins that are important in cell to cell communication, especially in the immune system) and growth factors to the same bout of exercise. From the arterial blood samples compared at rest and post-exercise, there were two differences that may help explain the growth inhibition associated with the exercise serum.

First, insulin-like growth factor binding protein (IGFBP-1) levels were 35% higher in the exercise serum. IGFBP-1 reduces the amount of active circulating IGF, which regulates cell proliferation and programmed cell death. High levels of circulating IGF have been associated with increased risk of prostate cancer, whereas higher levels of IGFBP-1 are associated with reduced risk.

Second, Epidermal growth factor (EGF) levels were 18% lower in the exercise serum. EGF stimulates the growth and proliferation of many cell types, including LNCaP prostate cancer cells. To summarize, arterial serum taken after an acute bout of aerobic exercise reduced the growth of cultured LNCaP prostate cancer cells by 31%. This inhibition may be due to increases in circulating levels of IGFBP-1 and decreases in EGF.

These data suggest that even a short, single bout of aerobic exercise may help to reduce the risk of prostate cancer.

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Thank you to Mike Baird for the photo /CC BY

Research Updates are compiled by Josh McKay, M.Sc. with guidance from the editorial board—using InspireHealth’s Research Information System, a unique integrative cancer care knowledge management database. The editorial team selects authoritative articles based on their evidence and their relevance to this area of medicine. The editorial board includes: Dr. Hal Gunn, MD, CEO and Co-founder, Dr. Janice Wright, MD, Dr. Hannah Nette, MD, Dr. Lori McFarlane, MD.  For more information, email library@inspirehealth.ca