The effect of single bout and prolonged aerobic exercise on tumor hypoxia in mice

Abstract

Objectives: The objectives were to investigate 1) the effect of acute aerobic exercise on tumour hypoxia and blood perfusion, 2) the impact of exercise intensity, 3) the duration of the effect, and 4) the effect of prolonged training on tumour hypoxia as well as tumour growth. Methods: Female CDF1 mice were inoculated with the C3H mammary carcinoma either in the mammary fat pad or subcutaneously in the back. For experiments on the effect of different intensities in a single exercise bout, mice were randomized to 30 min treadmill running low, moderate, or high intensity speeds or no exercise. To investigate the prolonged effect on hypoxia and tumour growth, tumour-bearing mice were randomized to no exercise (CON) or daily 30 min high-intensity exercise averaging two weeks (EX). Tumour hypoxic fraction was quantified using the hypoxia marker Pimonidazole. Results: Initially, high intensity exercise reduced tumour hypoxic fraction by 37% compared with CON (p=0.046; 95% CI: 0.1; 10.3) in fat pad tumours. Low and moderate intensities did not. Following experiments investigating the duration of the effect - as well as experiments in mice with back tumours - failed to show any exercise induced changes in hypoxia. Interestingly, prolonged daily training significantly reduced hypoxic fraction by 60% (p=0.002; 95% CI: 2.5;10.1) compared with CON. Conclusion: Despite diverging findings on the acute effect of exercise on hypoxia, our data indicate that if exercise has a diminishing effect, high-intensity exercise is needed. Prolonged training reduced tumour hypoxic fraction - cautiously suggesting a potential clinical potential.

Aerobic exercise training mitigates tumor growth and cancer-induced splenomegaly through modulation of non-platelet platelet factor 4 expression

“…Moreover, the studies have been focused on understanding the effects of exercise on platelet-derived Pf4 in the bloodstream 43 , 71 – 77 . Interestingly, it has been shown that exercise training can improve tumor angiogenesis and that it can be associated with the presence of functional blood vessels irrigating the tumor, therefore decreasing the hypoxia-reperfusion cycle 10 , 78 , 79 . Furthermore, we found that exercise training significantly reduced the percentage of hypoxic areas within the CT26 tumor compared to the CT26 tumor of untrained mice as measured using Hypoxyprobe (data not shown).…”

A study on lung cancer using nabla discrete fractional-order model

“…They performed a fixed point analysis to study the stability of the system and the sensitivity of the initial cell population. Other researchers have used fractional order models to investigate the effect of various factors on cancer growth such as the effects of hypoxia, the effects of radiotherapy, and the effects of anti-angiogenic therapy [40][41][42].…”