Exercise Inhibits Prostate Cancer Cell Growth

The common wisdom (in this case, an actual truth) is that every man will eventually develop prostate tumors if he lives long enough. Prostate cancer is the most common type of cancer in men and the second leading cause of death among men in the U.S. In 2008, the National Cancer Institute recorded 186,000 new cases and 28,600 deaths - those numbers are likely to have increased around 10% since 2008, in part due to better detection.

A 2012 meta-analysis of studies up to the that year identified a modest but significant protective factor for exercise (a reduction in risk for developing cancer). Further, several studies examining physical activity in relation to aggressive prostate cancer (about 10% of all PCa) and prostate cancer mortality also reported a significant risk reduction.

This new study shows that changes in the body chemistry during and immediately after exercise create a more aversive environment for PCa, inhibiting its growth.

As if we need another reason to exercise regularly, this is surely a good reason to do so.

Effect of Acute Exercise on Prostate Cancer Cell Growth

Helene Rundqvist, Martin Augsten, Anna Strömberg, Eric Rullman, Sara Mijwel, Pedram Kharaziha, Theocharis Panaretakis, Thomas Gustafsson, Arne Östman

Abstract

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. Long-term exercise is known to reduce serum levels of growth stimulating hormones. In contrast, the endocrine effects of acuteendurance 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.

Full Citation: 

Rundqvist H, Augsten M, Strömberg A, Rullman E, Mijwel S, et al. (2013, Jul 5). Effect of Acute Exercise on Prostate Cancer Cell Growth. PLoS ONE 8(7): e67579. doi:10.1371/journal.pone.0067579

Introduction

Prostate cancer is the second most frequent cancer diagnose in men in the world today. The highest incidence rates are found in the developed western countries and are 20 fold higher than the incidence rates found e.g. in South Central Asia and western Africa [1]. The discrepancy is partly due to the established use of PSA testing but lately a significant impact of life-style effects are being recognized [2]. Physical activity is an adjustable life-style factor associated with a reduced risk of several cancers, including prostate cancer [3].

A recent meta analysis comprising studies until 2012 suggests that being physically active is associated with a modest but significant reduction in risk of prostate cancer [4]. In addition, studies examining physical activity in relation to high-grade prostate cancer and prostate cancer mortality also reported a significant risk reduction [5]–[7].

The mechanisms mediating the effects of physical activity are not yet understood, although some candidates including weight control, improved immune cell function and modifications of endogenous hormone levels such as leptin, insulin and insulin like growth factor -1 (IGF-1) have been put forward [8]. Elevated serum levels of leptin, insulin and IGF-1 are all associated with high risk of prostate cancer incidence and progression [8]–[12] and long-term exercise is known to reduce serum levels of these and other endogenous hormones [13], [14].

Serum from endurance trained individuals on a low-fat, high-fiber diet has been shown to inhibit growth of an established prostate cancer cell line when compared to control serum [15]. More recent studies from the same group suggest that the mechanism behind the effect is mediated through the IGF-1 axis [16].

In contrast to long-term exercise, the endocrine effects of acute endurance exercise include increased levels of mitogenic factors such as growth hormone (GH) [17], various cytokines [18]including IL-6 [19], [20] and also increased bioavailability of IGF-1 [21], [22].

It can be speculated that the increase in serum growth factors induced by acute exercise 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.

Read the whole study.