Background – Many studies have documented that exercise and nutrition both have regulatory effects upon carcinogenesis. Indeed the progression of lesions and cancers can be reduced or eliminated. Both soy and whey proteins have been shown to have additional health benefits beyond their basic nutritional value, including anti- carcinogenic properties against colorectal, breast and prostate cancers. At present, limited knowledge exists of the mechanisms by which exercise and/or in combination with nutrition exhibit these anti-carcinogenic properties and whether anti-tumour properties extend to other tissues.
Objective – To determine the effects of moderate voluntary exercise on the incidence and progression of N- nitrosodiethylamine (NDEA)-induced, pre-neoplastic lesions and gene expression in the liver.
Design – Pre-neoplastic lesions were induced in the livers of Wistar rats by NDEA injections (25mg/kg body weight, 2 times week for 3 weeks). Rats (9 per treatment) were then allowed voluntary access to exercise for up to 12 weeks. Following euthanasia, liver samples were obtained and the total area occupied by preneoplastic lesions was determined by immunohistochemical staining for GST-yp. DNA microarray analysis was undertaken to investigate the effect of exercise upon gene expression.
Outcomes – This study found that pre-neoplastic lesions failed to progress after 9 and 12 weeks of exercise (P<0.01). Exercising also resulted in altered gene expression profiles which were consistent with enhancement of the immune system. Exercise also counteracted many of the effects upon gene expression due to the presence of lesions.
Conclusions – Moderate exercise has prevented the progression of NDEA-induced preneoplastic lesions in liver compared to sedentary controls possibly via a mechanism involving modulation of gene expression. The interactive effects of exercise with dietary change is being further investigated.