The effect of sport and physical activity on transport proteins: implications for cancer prevention and control.

The present contribution briefly overviews the major biological functions of the plasma membrane and of the transport proteins (transporters), which enable the movement of different molecules and substrates (either charged or uncharged) by passive (facilitated diffusion) or active transport. In particular, transporters are overviewed at the level of the skeletal muscles, which represent a highly complex, heterogeneous, plastic and dynamic tissue and are one of the most abundant tissues in humans, accounting for up to 40% of their total weight and containing up to 50%-75% of all body proteins. Moreover, it is shown how sport and physical activity finely tune and modulate human proteome, especially in terms of structural and functional improvements concerning the density of the transport proteins. These changes are among the factors responsible for the positive outcomes of training, which involve mainly the cardiovascular and the endocrine/metabolic systems. Different kinds of training (strength and endurance) enable to achieve such improvements, even though there seems to exist a dose-relationship intensity-dependent effect, with responses after 6-8 weeks of exercise and disappearing in the chronic period (years of training). Finally, exercise-induced changes at the level of transporters can play a role in terms of cancer prevention and management. Regular physical activity and exercise can, indeed, counteract the side-effects of chemotherapy drugs, including doxorubicin and other anthracycline derivatives, which may impair the functions of cardiac and skeletal muscles, probably modulating the expression of multidrug resistance proteins.