In 2006, over three million new cases of cancer were diagnosed in Europe, a number that is increasing as a result of an ageing population. Cardiac dysfunction was recently suggested as an overlooked morbidity related to cancer that may occur in tandem with cachexia. Modifiable health behaviors might redress such morbidity. Among healthy behaviors, exercise training has been successfully implemented has a therapeutic strategy in patients with heart failure, rescuing them from cardiac dysfunction, maladaptive remodeling and from the loss of skeletal muscle mass. Still, the impact of exercise training on cancer-related cardiac dysfunction was never addressed. Envisioning the mechanistically justification of endurance training recommendation to oncologic patients as a complementary therapy to protect cardiac function, we propose an one-year project that comprises an experimental approach based on the functional, morphological and proteomic characterization of cardiac muscle, using an animal model of chemical carcinogenesis of urothelial carcinoma (N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN))-induced muscle wasting. Previous experience from our group support the use of this animal model to study muscle wasting, which seems to be induced, at least partially, by cytokines’ burst related to urothelial carcinoma. We recently verified that these cytokines, particularly myostatin and TWEAK, also target the heart resulting in morphological alterations as fibrosis. Four experimental groups are projected: i) mice with urothelial carcinoma induced by oral exposition to BBN for 12 weeks followed by 8 weeks of tap water (BBN+SED group); ii) mice with urothelial carcinoma induced by oral exposition to BBN for 12 weeks followed by 8 weeks of tap water and endurance training (BBN+EX group); iii) healthy mice, with free access to tap water during all the protocol (CONT+SED); iv) healthy mice, with free access to tap water, that start an exercise program 12 weeks after the beginning of the protocol (CONT+EX). Animals from EX groups will be exercised on a treadmill for 60min/day at a speed of 20m/min, 5days/week for 8 weeks, which is estimated to cause cardiovascular adaptations. Once finished the protocol, hemodynamic analysis will be performed for cardiac functionality assessment. In serum, biochemical markers of a wasting phenotype will be assayed. Small sections of the cardiac muscle will be used for morphological analysis and the remaining tissue for proteomics. Besides the signaling pathways modulated in heart by tumor burden-induced cytokines, emphasis will be given to the mitochondrial protein networks in heart modulated by cancer and/or exercise. This strategy was projected considering that mitochondria is the place of energy wasting and the observation that mitochondrial dysfunction occurs in muscle wasting. We will also look at phosphorylated proteins since mitochondrial plasticity relies on a range of reversible protein post-translational modifications as phosphorylation. Off-gel approaches coupled with MS and iTRAQs quantification will be used to identify the proteins and phosphoproteins differentially expressed between groups. The assignment of these proteins to the corresponding cellular pathways with bioinformatic tools will allow the identification of the molecular mechanisms modulated in heart by carcinogenesis and/or exercise. Proteomic results will be further correlated with morphological and biochemical data, aiming a global perspective of the molecular mechanisms modulated in heart by cancer and counteracted by exercise. We expect to mechanistically justify the recommendation of moderate endurance training once cancers-diagnose has been established, as a complementary therapy to protect cardiac function. For the successful accomplishment of the present proposal, we will take advantage of a multidisciplinary team with complementary scientific backgrounds, also supported by the laboratory facilities and equipment required through the involvement of different research units (CIAFEL/UP; QOPNA/UA; UTAD).
Universidade de Aveiro