Curing the cure: utilizing exercise to limit cardiotoxicity

Exercise Cardio-Oncology: Exercise as a Potential Therapeutic Modality in the Management of Anthracycline-Induced Cardiotoxicity

Anthracyclines are one of the most effective chemotherapy agents and have revolutionized cancer therapy. However, anthracyclines can induce cardiac injuries through ‘multiple-hits', a series of cardiovascular insults coupled with lifestyle risk factors, which increase the risk of developing short- and long-term cardiac dysfunction and cardiovascular disease that potentially lead to premature mortality following cancer remission. Therefore, the management of anthracycline-induced cardiotoxicity is a serious unmet clinical need. Exercise therapy, as a non-pharmacological intervention, stimulates numerous biochemical and physiologic adaptations, including cardioprotective effects, through the cardiovascular system and cardiac muscles, where exercise has been proposed to be an effective clinical approach that can protect or reverse the cardiotoxicity from anthracyclines. Many preclinical and clinical trials demonstrate the potential impacts of exercise on cardiotoxicity; however, the underlying mechanisms as well as how to implement exercise in clinical settings to improve or protect against long-term cardiovascular disease outcomes are not clearly defined. In this review, we summarize the current evidence in the field of “exercise cardio-oncology” and emphasize the utilization of exercise to prevent and manage anthracycline-induced cardiotoxicities across high-risk and vulnerable populations diagnosed with cancer.

Survivorship, Version 2.2018, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Survivorship provide screening, evaluation, and treatment recommendations for common physical and psychosocial consequences of cancer and cancer treatment to help healthcare professionals who work with survivors of adult-onset cancer in the posttreatment period. This portion of the guidelines describes recommendations regarding the management of anthracycline-induced cardiotoxicity and lymphedema. In addition, recommendations regarding immunizations and the prevention of infections in cancer survivors are included.

The beneficial role of exercise in mitigating doxorubicin-induced Mitochondrionopathy

Doxorubicin (DOX) is a widely used antineoplastic agent for a wide range of cancers, including hematological malignancies, soft tissue sarcomas and solid tumors. However, DOX exhibits a dose-related toxicity that results in life-threatening cardiomyopathy. In addition to the heart, there is evidence that DOX toxicity extends to other organs. This general toxicity seems to be related to mitochondrial network structural, molecular and functional impairments. Several countermeasures for these negative effects have been proposed, being physical exercise, not only one of the most effective non-pharmacologic strategy but also widely recommended as booster against cancer-related fatigue. It is widely accepted that mitochondria are critical sensors of tissue functionality, both modulated by DOX and exercise. Therefore, this review focuses on the current understanding of the mitochondrial-mediated mechanisms underlying the protective effect of exercise against DOX-induced toxicity, not only limited to the cardiac tissue, but also in other tissues such as skeletal muscle, liver and brain. We here analyze recent developments regarding the beneficial effects of exercise targeting mitochondrial responsive phenotypes against redox changes, mitochondrial bioenergetics, apoptotic, dynamics and quality control signalling affected by DOX treatment.

Can exercise training counteract doxorubicin-induced oxidative damage of testis proteome?

The use of the chemotherapeutic drug doxorubicin (DOX) is limited by its toxicity in several organs such as testes. So, we analyzed the effect of endurance treadmill exercise training (EX) performed before sub-chronic DOX treatment on sperm count and motility, testes markers of oxidative damage and apoptosis. Tissue profiling of proteins more susceptible to oxidation was made to identify the molecular pathways regulated by oxidative modifications, as nitration and carbonylation. Twenty-four adult male rats were divided into four groups (n=6/group): sedentary saline (SED+SAL), sedentary sub-chronically injected with DOX (2mg-kg-1 per week, during 7 weeks; SED+DOX), 12 weeks trained saline (EX+SAL) and trained treated with DOX (EX+DOX). DOX treatment started 5 weeks after the beginning of the exercise program. Testes caspase-3, -8 and -9, as well as aconitase activities, the content of malondialdehyde (MDA), sulfhydryl groups (-SH), carbonyl and nitrotyrosine derivatives were determined. Modified proteins were identified by 2D-Western blot followed by MALDI-TOF/TOF mass spectrometry, and bioinformatic analysis was performed to assess the biological processes regulated by these chemical modifications. The decreased sperm motility induced by DOX was not modified by exercise. Significant increases in MDA content in SED+DOX and in caspase-3 and -9 activities in EX+DOX were found. Despite no significant differences in the levels of carbonylated and nitrated proteins, exercise modulated testis proteome susceptibility to oxidation in DOX-treated group, with less modified proteins identified. Zinc finger Ran-binding domain-containing protein 2 (ZRAB2) and AN1-type zinc finger protein 3 (ZFAN3) were among the proteins found oxidativelly modified. Although no marked alterations in testes oxidative damage were noticed, proteomic analysis of oxidativelly modified proteins highlighted the protective role of exercise against oxidative damage of some proteins involved in metabolism and stress response against DOX.

Exercise Prevention of Cardiovascular Disease in Breast Cancer Survivors

Thanks to increasingly effective treatment, breast cancer mortality rates have significantly declined over the past few decades. Following the increase in life expectancy of women diagnosed with breast cancer, it has been recognized that these women are at an elevated risk for cardiovascular disease due in part to the cardiotoxic side effects of treatment. This paper reviews evidence for the role of exercise in prevention of cardiovascular toxicity associated with chemotherapy used in breast cancer, and in modifying cardiovascular risk factors in breast cancer survivors. There is growing evidence indicating that the primary mechanism for this protective effect appears to be improved antioxidant capacity in the heart and vasculature and subsequent reduction of treatment-related oxidative stress in these structures. Further clinical research is needed to determine whether exercise is a feasible and effective nonpharmacological treatment to reduce cardiovascular morbidity and mortality in breast cancer survivors, to identify the cancer therapies for which it is effective, and to determine the optimal exercise dose. Safe and noninvasive measures that are sensitive to changes in cardiovascular function are required to answer these questions in patient populations. Cardiac strain, endothelial function, and cardiac biomarkers are suggested outcome measures for clinical research in this field.

Physical exercise prior and during treatment reduces sub-chronic doxorubicin-induced mitochondrial toxicity and oxidative stress

Doxorubicin (DOX) is an anti-cancer agent whose clinical usage results in a cumulative and dose-dependent cardiotoxicity. We have previously shown that exercise performed prior to DOX treatment reduces the resulting cardiac(mito) toxicity. We sought to determine the effects on cardiac mitochondrial toxicity of two distinct chronic exercise models (endurance treadmill training-TM and voluntary free-wheel activity-FW) when used prior and during DOX treatment. Male-young Sprague-Dawley rats were divided into six groups (n=6 per group): SAL+SED (saline sedentary), SAL+TM (12-weeks TM), SAL+FW (12-weeks FW), DOX+SED (7-weeks of chronic DOX treatment 2mg/kg per week), DOX+TM and DOX+FW. DOX administration started 5weeks after the beginning of the exercise protocol. Heart mitochondrial ultrastructural alterations, mitochondrial function (oxygen consumption and membrane potential), semi-quantification of oxidative phosphorylation (OXPHOS) proteins and their in-gel activity, as well as proteins involved in mitochondrial oxidative stress (SIRT3, p66shc and UCP2), biogenesis (PGC1α and TFAM), acetylation and markers for oxidative damage (carbonyl groups, MDA,SH, aconitase, Mn-SOD activity) were evaluated. DOX treatment resulted in ultrastructural and functional alterations and decreased OXPHOS. Moreover, DOX decreased complex I activity and content, mitochondrial biogenesis (TFAM), increased acetylation and oxidative stress. TM and FW prevented DOX-induced alteration in OXPHOS, the increase in oxidative stress, the decrease in complex V activity and in complex I activity and content. DOX-induced decreases in TFAM and SIRT3 content were prevented by TM only. Both chronic models of physical exercise performed before and during the course of sub-chronic DOX treatment translated into an improved mitochondrial bioenergetic fitness, which may result in part from the prevention of mitochondrial oxidative stress and damage.

Overweight female rats selectively breed for low aerobic capacity exhibit increased myocardial fibrosis and diastolic dysfunction

The statistical association between endurance exercise capacity and cardiovascular disease suggests that impaired aerobic metabolism underlies the cardiovascular disease risk in men and women. To explore this connection, we applied divergent artificial selection in rats to develop low-capacity runner (LCR) and high-capacity runner (HCR) rats and found that disease risks segregated strongly with low running capacity. Here, we tested if inborn low aerobic capacity promotes differential sex-related cardiovascular effects. Compared with HCR males (HCR-M), LCR males (LCR-M) were overweight by 34% and had heavier retroperitoneal, epididymal, and omental fat pads; LCR females (LCR-F) were 20% heavier than HCR females (HCR-F), and their retroperitoneal, but not perireproductive or omental, fat pads were heavier as well. Unlike HCR-M, blood pressure was elevated in LCR-M, and this was accompanied by left ventricular (LV) hypertrophy. Like HCR-F, LCR-F exhibited normal blood pressure and LV weight as well as increased spontaneous cage activity compared with males. Despite normal blood pressures, LCR-F exhibited increased myocardial interstitial fibrosis and diastolic dysfunction, as indicated by increased LV stiffness, a decrease in the initial filling rate, and an increase in diastolic relaxation time. Although females exhibited increased arterial stiffness, ejection fraction was normal. Increased interstitial fibrosis and diastolic dysfunction in LCR-F was accompanied by the lowest protein levels of phosphorylated AMP-actived protein kinase [phospho-AMPK (Thr(172))] and silent information regulator 1. Thus, the combination of risk factors, including female sex, intrinsic low aerobic capacity, and overweightness, promote myocardial stiffness/fibrosis sufficient to induce diastolic dysfunction in the absence of hypertension and LV hypertrophy.

Exercise as a beneficial adjunct therapy during Doxorubicin treatment--role of mitochondria in cardioprotection

One of the mostly used chemotherapeutic drugs is the highly effective anthracycline Doxorubicin. However, its clinical use is limited by the dose-related and cumulative cardiotoxicity and consequent dysfunction. It has been proposed that the etiology of this toxicity is related to mitochondrial dysfunction. The present review aimed to analyze the promising results regarding the effect of several types of physical exercise in cardiac tolerance of animals treated with acute and sub-chronic doses of Doxorubicin (DOX), highlighting the importance of cardiac mitochondrial-related mechanisms in the process. Physical exercise positively modulates some important cardiac defense systems to antagonize the toxic effects caused by DOX treatment, including antioxidant capacity, the overexpression of heat shock proteins and other anti-apoptotic proteins. An important role in this protective phenotype afforded by exercise should be attributed to mitochondrial plasticity, as related adaptations could be translated into improved cardiac function in the setting of the DOX cardiomyopathy.