Exercise training mitigates anthracycline-induced chronic cardiotoxicity in a juvenile rat model

Exercise Preconditioning Preserves Cardiac Function and Enhances Cardiac Recovery Following Dobutamine Stimulation in Doxorubicin-Treated Rat Hearts

ABSTRACT

Exercise preconditioning has been shown to protect against doxorubicin (DOX)-induced cardiac dysfunction when hearts are maintained under resting conditions. However, it is unclear whether this exercise-induced protective effect is maintained when the heart is challenged with the β 1 -adrenergic receptor agonist dobutamine (DOB), which mimics acute exercise stress. Fischer 344 rats were randomly assigned to sedentary (SED) or voluntary wheel running (WR) groups for 10 weeks. At week 11, rats were treated with either 15 mg/kg DOX or saline. Five days later, ex vivo cardiac function was assessed using an isolated working heart model at baseline, during the infusion of 7.5 μg·kg -1 ·min -1 DOB, and during recovery. DOB infusion significantly increased left ventricular developed pressure (LVDP), maximal (dP/dt max ) and minimal (dP/dt min ) rate of left ventricular pressure development, and heart rate in all groups ( P < 0.05). SED + DOX also showed a lower baseline and recovery LVDP than WR + DOX (83 ± 12 vs. 109 ± 6 mm Hg baseline, 76 ± 11 vs. 100 ± 10 mm Hg recovery, P < 0.05). WR + DOX showed higher dP/dt max and lower dP/dt min when compared with SED + DOX during DOB infusion (7311 ± 1481 vs. 5167 ± 1436 mm Hg/s and -4059 ± 1114 vs.-3158 ± 1176 mm Hg/s, respectively). SED + DOX dP/dt max was significantly lower during baseline and during recovery when compared with all other groups ( P < 0.05). These data suggest that exercise preconditioning preserved cardiac function after DOX exposure even when the heart is challenged with DOB, and it appeared to preserve the heart's ability to recover from this functional challenge.

The Impact of Exercise on Cardiotoxicity in Pediatric and Adolescent Cancer Survivors: A Scoping Review

Childhood and adolescent cancer survivors are disproportionately more likely to develop cardiovascular diseases from the late effects of cardiotoxic therapies (e.g., anthracycline-based chemotherapy and chest-directed radiotherapy). Currently, dexrazoxane is the only approved drug for preventing cancer treatment-related cardiac damage. While animal models highlight the beneficial effects of exercise cancer treatment-related cardiac dysfunction, few clinical studies have been conducted. Thus, the objective of this scoping review was to explore the designs and impact of exercise-based interventions for managing cancer treatment-related cardiac dysfunction in childhood and adolescent cancer survivors. Reviewers used Joanna Briggs Institute’s methodology to identify relevant literature. Then, 4616 studies were screened, and three reviewers extracted relevant data from six reports. Reviewers found that exercise interventions to prevent cancer treatment-related cardiac dysfunction in childhood and adolescent cancer survivors vary regarding frequency, intensity, time, and type of exercise intervention. Further, the review suggests that exercise promotes positive effects on managing cancer treatment-related cardiac dysfunction across numerous indices of heart health. However, the few clinical studies employing exercise interventions for childhood and adolescent cancer survivors highlight the necessity for more research in this area.

Health effects of outdoor water sports in chronic disease: a scoping review

Background

Although outdoor water sport activities are gaining increasing attention for their therapeutic potential in the social and care management of populations with chronic diseases, these practices are currently underutilised. Moreover, the available body of literature on the topic has not been critically and comprehensively assessed yet.

Aims

(1) To appraise the health effects of outdoor water sport activities for chronic disease populations; (2) to preliminarily assess the potential size and scope of the available research literature for this emerging field and identify potential gaps and avenues of development.

Methods

A literature search was performed scanning PubMed (including MEDLINE), Physiotherapy Evidence Database (PEDro) and Scopus from inception to December 2021. A scoping review was carried out by appraising all the available evidence on outdoor water sport interventions specifically designed for therapeutic purposes for individuals with chronic disease. The quality score of each study was calculated with the Tool for the assEssment of Study qualiTy and reporting in Exercise (TESTEX) tool.

Results

Fifteen studies (five RCTs, seven non-RCTs and three CTs with healthy subjects as controls) met the inclusion criteria and were assessed. Among the studies selected, two focused on canoa kayak, one on stand-up paddle, two on surfing, two on sailing activity, and eight on dragon boat padding. The median TESTEX score for study quality and reporting was 6/15, i.e., “very low” (range 5–8). Based on the qualitative analysis, the few individual studies that could be included reported generally positive results, ranging from improvements in antioxidant action and cardiovascular function for dragon boating, to beneficial effects on balance, postural control, and flexibility for on-water paddle board activities. Overall, outdoor water sport interventions were associated to higher rates of adherence than conventional trainings.

Conclusions

Very low to low quality evidence from a limited set of pilot studies seems to suggest beneficial effects of outdoor water sports for chronic disease populations. However, such preliminary findings need to be replicated through large, high-quality RCTs to be conducted in target populations. Avenues of development, scoping directions and translational perspectives for this specific research field are proposed and discussed.

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.

Dual integrin αvβ3 and αvβ5 blockade attenuates cardiac dysfunction by reducing fibrosis in a rat model of doxorubicin-induced cardiomyopathy

OBJECTIVE

The present study aimed to evaluate the protective role of cilengitide (CGT), an integrin αvβ3 and αvβ5 inhibitor, on doxorubicin (DOX)-induced myocardial fibrosis and cardiac dysfunction in a rat model. Methods. Forty male rats were randomly divided into four groups: DOX (n = 12), intraperitoneal (i.p.) injection of DOX 0.8 ∼ 1.0 mg/kg three times a week for up to 6 weeks, then saline i.p. three times a week for another 3 weeks; CGT (n = 8), CGT 10 mg/kg, i.p. three times a week for 9 weeks; DOX + CGT (n = 12), DOX and CGT co-administration as above for 6 weeks, then CGT alone for another 3 weeks; Control (n = 8), saline i.p. three times a week for 9 weeks. Echocardiography, serum procollagen I C-terminal propeptide (PICP) procollagen III N-terminal propeptide (PIIINP) and C telopeptide type I (CTX-I) were evaluated at baseline and 3, 6 and 9 weeks after initial DOX administration for all surviving rats. The heart tissues were then harvested for myocardial hydroxyproline (HYP) evaluation, qRT-PCR, and western blotting. Results. CGT attenuated DOX-induced eccentric remodeling by improving relative wall thickness at the 9th week. CGT also improved systolic function at the 9th week and diastolic function at the 6th and 9th week. CGT reduced myocardial HYP and serum PICP, PIIINP, CTX-I, and the PICP/PIIINP ratio. RT-PCR and western blot showed that CGT blocked the TGF-β1/SMAD3 pathway and mitigating extracellular matrix turnover. Conclusions. CGT exerted a cardioprotective effect against doxorubicin-induced fibrosis and improved cardiac function.

Efficacy of Physical Exercise to Offset Anthracycline-Induced Cardiotoxicity: A Systematic Review and Meta-Analysis of Clinical and Preclinical Studies

Background

Physical exercise is an intervention that might protect against doxorubicin‐induced cardiotoxicity. In this meta‐analysis and systematic review, we aimed to estimate the effect of exercise on doxorubicin‐induced cardiotoxicity and to evaluate mechanisms underlying exercise‐mediated cardioprotection using (pre)clinical evidence.

Methods and Results

We conducted a systematic search in PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases. Cochrane's and Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk‐of‐bias tools were used to assess the validity of human and animal studies, respectively. Cardiotoxicity outcomes reported by ≥3 studies were pooled and structured around the type of exercise intervention. Forty articles were included, of which 3 were clinical studies. Overall, in humans (sample sizes ranging from 24 to 61), results were indicative of exercise‐mediated cardioprotection, yet they were not sufficient to establish whether physical exercise protects against doxorubicin‐induced cardiotoxicity. In animal studies (n=37), a pooled analysis demonstrated that forced exercise interventions significantly mitigated in vivo and ex vivo doxorubicin‐induced cardiotoxicity compared with nonexercised controls. Similar yet slightly smaller effects were found for voluntary exercise interventions. We identified oxidative stress and related pathways, and less doxorubicin accumulation as mechanisms underlying exercise‐induced cardioprotection, of which the latter could act as an overarching mechanism.

Conclusions

Animal studies indicate that various exercise interventions can protect against doxorubicin‐induced cardiotoxicity in rodents. Less doxorubicin accumulation in cardiac tissue could be a key underlying mechanism. Given the preclinical evidence and limited availability of clinical data, larger and methodologically rigorous clinical studies are needed to clarify the role of physical exercise in preventing cardiotoxicity in patients with cancer.

Registration

URL: https://www.crd.york.ac.uk/prospero; Unique identifier: CRD42019118218.

Exercise, but Not Metformin Prevents Loss of Muscle Function Due to Doxorubicin in Mice Using an In Situ Method

Though effective in treating various types of cancer, the chemotherapeutic doxorubicin (DOX) is associated with skeletal muscle wasting and fatigue. The purpose of this study was to assess muscle function in situ following DOX administration in mice. Furthermore, pre-treatments with exercise (EX) or metformin (MET) were used in an attempt to preserve muscle function following DOX. Mice were assigned to the following groups: control, DOX, DOX + EX, or DOX + MET, and were given a single injection of DOX (15 mg/kg) or saline 3 days prior to sacrifice. Preceding the DOX injection, DOX + EX mice performed 60 min/day of running for 5 days, while DOX + MET mice received 5 daily oral doses of 500 mg/kg MET. Gastrocnemius–plantaris–soleus complex function was assessed in situ via direct stimulation of the sciatic nerve. DOX treatment increased time to half-relaxation following contractions, indicating impaired recovery (p < 0.05). Interestingly, EX prevented any increase in half-relaxation time, while MET did not. An impaired relaxation rate was associated with a reduction in SERCA1 protein content (p = 0.07) and AMPK phosphorylation (p < 0.05). There were no differences between groups in force production or mitochondrial respiration. These results suggest that EX, but not MET may be an effective strategy for the prevention of muscle fatigue following DOX administration in mice.

Doxorubicin Paradoxically Ameliorates Tumor-Induced Inflammation in Young Mice

Doxorubicin (DOX) is one of the most widely used chemo-therapeutic agents in pediatric oncology. DOX elicits an inflammatory response in multiple organs, which contributes to DOX-induced adverse effects. Cancer itself causes inflammation leading to multiple pathologic conditions. The current study investigated the inflammatory response to DOX and tumors using an EL4-lymphoma, immunocompetent, juvenile mouse model. Four-week old male C57BL/6N mice were injected subcutaneously with EL4 lymphoma cells (5 × 10⁴ cells/mouse) in the flank region, while tumor-free mice were injected with vehicle. Three days following tumor implantation, both tumor-free and tumor-bearing mice were injected intraperitoneally with either DOX (4 mg/kg/week) or saline for 3 weeks. One week after the last DOX injection, the mice were euthanized and the hearts, livers, kidneys, and serum were harvested. Gene expression and serum concentration of inflammatory markers were quantified using real-time PCR and ELISA, respectively. DOX treatment significantly suppressed tumor growth in tumor-bearing mice and caused significant cardiac atrophy in tumor-free and tumor-bearing mice. EL4 tumors elicited a strong inflammatory response in the heart, liver, and kidney. Strikingly, DOX treatment ameliorated tumor-induced inflammation paradoxical to the effect of DOX in tumor-free mice, demonstrating a widely divergent effect of DOX treatment in tumor-free versus tumor-bearing mice.

Evidence-based prediction and prevention of cardiovascular morbidity in adults treated for cancer

BACKGROUND

Cancer treatment-related morbidity relevantly compromises health status in cancer survivors, and efforts to optimise health-related outcomes in this population are vital to maximising healthy survivorship. A pre-treatment assessment - and possibly preventive management strategies - of cancer patients at increased risk for cardiovascular disease (CVD) seems a rational approach in this regard. Definitive evidence for such strategies is largely lacking, thereby impeding the formulation of firm recommendations.

RESULTS

The current scoping review aims to summarise and grade the evidence regarding strategies for prediction and prevention of CVD in adults in relation to oncological treatments. We conducted a scoping literature search for different strategies for primary prevention, such as medical and lifestyle interventions, as well as the use of predictive risk scores. We identified studies with moderate to good strength and up to now limited evidence to recommend primary preventive strategies in unselected patients treated with potentially cardiotoxic oncologic therapies.

CONCLUSION

Efforts to minimize the CVD burden in cancer survivors are needed to accomplish healthy survivorship. This can be done by means of robust models predictive for CVD events or application of interventions during or after oncological treatments. Up to now there is insufficient evidence to implement preventive strategies in an unselected group of patients treated with potential cardiotoxic oncological treatments. We conclude that randomised controlled trials are needed that evaluate medical and lifestyle interventions in groups at increased risk for complications, in order to be able to influence chronic illness risks, such as cardiovascular complications, for cancer survivors.

Cardioprotective effects of exercise training on doxorubicin-induced cardiomyopathy: a systematic review with meta-analysis of preclinical studies

Doxorubicin (DOX)-induced cardiotoxicity in chemotherapy is a major treatment drawback. Clinical trials on the cardioprotective effects of exercise in cancer patients have not yet been published. Thus, we conducted a systematic review and meta-analysis of preclinical studies for to assess the efficacy of exercise training on DOX-induced cardiomyopathy. We included studies with animal models of DOX-induced cardiomyopathy and exercise training from PubMed, Web of Sciences and Scopus databases. The outcome was the mean difference (MD) in fractional shortening (FS, %) assessed by echocardiography between sedentary and trained DOX-treated animals. Trained DOX-treated animals improved 7.40% (95% CI 5.75-9.05, p < 0.001) in FS vs. sedentary animals. Subgroup analyses revealed a superior effect of exercise training execution prior to DOX exposure (MD = 8.20, 95% CI 6.27-10.13, p = 0.010). The assessment of cardiac function up to 10 days after DOX exposure and completion of exercise protocol was also associated with superior effect size in FS (MD = 7.89, 95% CI 6.11-9.67, p = 0.020) vs. an echocardiography after over 4 weeks. Modality and duration of exercise, gender and cumulative DOX dose did were not individually associated with changes on FS. Exercise training is a cardioprotective approach in rodent models of DOX-induced cardiomyopathy. Exercise prior to DOX exposure exerts greater effect sizes on FS preservation.

Antioxidant Approach as a Cardioprotective Strategy in Chemotherapy-Induced Cardiotoxicity

Significance: Chemotherapy-induced cardiotoxicity (CTX) has been associated with redox signaling imbalance. In fact, redox reactions are crucial for normal heart physiology, whereas excessive oxidative stress can cause cardiomyocyte structural damage. Recent Advances: An antioxidant approach as a cardioprotective strategy in this setting has shown encouraging results in preventing anticancer drug-induced CTX. Critical Issues: In fact, traditional heart failure drugs as well as many other compounds and nonpharmacological strategies, with a partial effect in reducing oxidative stress, have been shown to counterbalance chemotherapy-induced CTX in this setting to some extent. Future Directions: Given the various pathways of toxicity involved in different chemotherapeutic schemes, interactions with redox balance need to be fine-tuned and a personalized cardioprotective approach seems to be required.

Aerobic Exercise and Cardiac Function of Murines Exposed to Doxorubicin: a Meta-Analysis

Fundamento:

A cardiotoxicidade pode ser uma consequência do tratamento com doxorrubicina (DOX).

Objetivos:

Verificar o efeito do exercício aeróbio na prevenção da disfunção cardíaca de murinos expostos à DOX.

Método:

Uma busca abrangente foi realizada em nove bases de dados, em dezembro de 2017. Estudos que avaliaram a função cardíaca de murinos expostos à DOX foram incluídos. O nível de significância adotado foi de 5%.

Resultados:

Na comparação entre 230 murinos submetidos a exercício aeróbio mais DOX e 222 controles (tratados somente com DOX), a fração de encurtamento mostrou uma melhora de 5,33% a favor do grupo experimental (p = 0,0001). A pressão desenvolvida no ventrículo esquerdo também mostrou um aumento de 24,84 mmHg a favor do grupo de 153 murinos que realizaram exercício em comparação com o grupo controle de 166 murinos (p = 0,00001).

Conclusão:

Estudos pré-clínicos incluídos nesta metanálise indicaram que o exercício é uma boa estratégia não farmacológica para preservar a função cardíaca pós-DOX.

Endurance Exercise Attenuates Doxorubicin-induced Cardiotoxicity

PURPOSE

Endurance exercise (EXE) preconditioning before DOX treatment confers cardioprotection; however, whether EXE postconditioning (i.e., EXE intervention after the completion of DOX treatment) is cardioprotective remains unknown. Thus, the aim of the present study was to investigate if EXE postconditioning provides cardioprotection by testing the hypothesis that EXE-autophagy upregulation and NADPH oxidase 2 (NOX2) downregulation would be linked to cardioprotection against DOX-induced cardiotoxicity.

METHODS

C57BL/6 male mice were assigned into three groups: control (CON, n = 10), doxorubicin (DOX, n = 10), and doxorubicin + endurance exercise (DOX + EXE, n = 10). Animals assigned to DOX and DOX + EXE groups were intraperitoneally injected with DOX (5 mg·kg each week for 4 wk). Forty-eight hours after the last DOX treatment, the mice assigned to DOX + EXE performed EXE on a motorized treadmill at a speed of 13-15 m·min for 60 min·d for 4 wk.

RESULTS

EXE prevented DOX-induced apoptosis and mitigated tissue damages. Although DOX did not modulate auto/mitophagy, EXE significantly enhanced its flux (increased LC3-II levels, reduced p62 levels, and increased autophagosomes with mitochondria) along with increased mitochondrial fission (DRP1) and reduced fusion markers (OPA1 and MFN2). Interestingly, EXE-induced autophagy against DOX occurred in the absence of alterations of autophagy inducer AMPK or autophagy inhibitor mTOR signaling. EXE prohibited DOX-induced oxidative damages by suppressing NOX2 levels but without modulating other key antioxidant enzymes including MnSOD, CuZnSOD, catalase, and GPX1/2.

CONCLUSION

Our data provide novel findings that EXE-induced auto/mitophagy promotion and NOX2 downregulation are linked to cardioprotection against DOX-induced cardiotoxicity. Importantly, our study shows that EXE postconditioning intervention is effective and efficacious to prevent DOX-induced cardiac injuries.

Mechanisms Involved in Cardioprotection Induced by Physical Exercise

Significance: Regular exercise training can reduce myocardial damage caused by acute ischemia/reperfusion (I/R). Exercise can reproduce the phenomenon of ischemic preconditioning, due to the capacity of brief periods of ischemia to reduce myocardial damage caused by acute I/R. In addition, exercise may also activate the multiple kinase cascade responsible for cardioprotection even in the absence of ischemia. Recent Advances: Animal and human studies highlighted the fact that, besides to reduce risk factors related to cardiovascular disease, the beneficial effects of exercise are also due to its ability to induce conditioning of the heart. Exercise behaves as a physiological stress that triggers beneficial adaptive cellular responses, inducing a protective phenotype in the heart. The factors contributing to the exercise-induced heart preconditioning include stimulation of the anti-radical defense system and nitric oxide production, opioids, myokines, and adenosine-5'-triphosphate (ATP) dependent potassium channels. They appear to be also involved in the protective effect exerted by exercise against cardiotoxicity related to chemotherapy. Critical Issues and Future Directions: Although several experimental evidences on the protective effect of exercise have been obtained, the mechanisms underlying this phenomenon have not yet been fully clarified. Further studies are warranted to define precise exercise prescriptions in patients at risk of myocardial infarction or undergoing chemotherapy.

Angiotensin-(1–7) reduces doxorubicin-induced cardiac dysfunction in male and female Sprague-Dawley rats through antioxidant mechanisms

Doxorubicin (Dox) is an effective chemotherapeutic for a variety of pediatric malignancies. Unfortunately, Dox administration often results in a cumulative dose-dependent cardiotoxicity that manifests with marked oxidative stress, leading to heart failure. Adjunct therapies are needed to mitigate Dox cardiotoxicity and enhance quality of life in pediatric patients with cancer. Angiotensin-(1–7) [Ang-(1–7)] is an endogenous hormone with cardioprotective properties. This study investigated whether adjunct Ang-(1–7) attenuates cardiotoxicity resulting from exposure to Dox in male and female juvenile rats. Dox significantly reduced body mass, and the addition of Ang-(1–7) had no effect. However, adjunct Ang-(1–7) prevented Dox-mediated diastolic dysfunction, including markers of decreased passive filling as measured by reduced early diastole mitral valve flow velocity peak ( E) ( P < 0.05) and early diastole mitral valve annulus peak velocity ( e′; P < 0.001) and increased E/e′ ( P < 0.001), an echocardiographic measure of diastolic dysfunction. Since Dox treatment increases reactive oxygen species (ROS), the effect of Ang-(1–7) on oxidative by-products and enzymes that generate or reduce ROS was investigated. In hearts of male and female juvenile rats, Dox increased NADPH oxidase 4 ( P < 0.05), a major cardiovascular NADPH oxidase isozyme that generates ROS, as well as 4-hydroxynonenal ( P < 0.001) and malondialdehyde ( P < 0.001), markers of lipid peroxidation; Ang-(1–7) prevented these effects of Dox. Cotreatment with Dox and Ang-(1–7) increased the antioxidant enzymes SOD1 (male: P < 0.05; female: P < 0.01) and catalase ( P < 0.05), which likely contributed to reduced ROS. These results demonstrate that Ang-(1–7) prevents diastolic dysfunction in association with a reduction in ROS, suggesting that the heptapeptide hormone may serve as an effective adjuvant to improve Dox-induced cardiotoxicity.

NEW & NOTEWORTHY Ang-(1–7) is a clinically safe peptide hormone with cardioprotective and antineoplastic properties that could be used as an adjuvant therapy to improve cancer treatment and mitigate the long-term cardiotoxicity associated with doxorubicin in pediatric patients with cancer.

Co-administration of resveratrol with doxorubicin in young mice attenuates detrimental late-occurring cardiovascular changes

Aims

Doxorubicin (DOX) is among the most effective chemotherapies used in paediatric cancer patients. However, the clinical utility of DOX is offset by its well-known cardiotoxicity, which often does not appear until later in life. Since hypertension significantly increases the risk of late-onset heart failure in childhood cancer survivors, we investigated whether juvenile DOX exposure impairs the ability to adapt to angiotensin II (Ang II)-induced hypertension later in life and tested a treatment that could prevent this.

Methods and results

Five-week-old male mice were administered a low dose of DOX (4 mg/kg) or saline once a week for 3 weeks and then allowed to recover for 5 weeks. Following the 5-week recovery period, mice were infused with Ang II or saline for 2 weeks. In another cohort, mice were fed chow containing 0.4% resveratrol 1 week before, during, and 1 week after the DOX administrations. One week after the last DOX administration, p38 mitogen-activated protein kinase (MAPK) was activated in hearts of DOX-treated mice demonstrating molecular signs of cardiac stress; yet, there was no change in cardiac function between groups. However, DOX-treated mice failed to develop compensatory cardiac hypertrophy in response to Ang II-induced hypertension later in life. Of importance, mice receiving DOX with resveratrol co-administration displayed normalization in p38 MAPK activation in the heart and a restored capacity for cardiac hypertrophy in response to Ang II-induced hypertension.

Conclusion

We have developed a juvenile mouse model of DOX-induced cardiotoxicity that displays no immediate overt physiological dysfunction; but, leads to an impaired ability of the heart to adapt to hypertension later in life. We also show that co-administration of resveratrol during DOX treatment was sufficient to normalize molecular markers of cardiotoxicity and restore the ability of the heart to undergo adaptive remodelling in response to hypertension later in life.

l-arginine alleviates doxorubicin-induced endothelium-dependent dysfunction by promoting nitric oxide generation and inhibiting apoptosis

BACKGROUND/AIMS

Patients with doxorubicin (Dox) treatment have a high risk of developing vascular toxicity with an unknown mechanism. l-arginine is a substrate for nitric oxide (NO). The decreased level of arginine-NO metabolite in Dox-treated cancer patients was associated with increased level of vascular damage, which promoted us to investigate the mechanism of Dox-induced vascular dysfunction and verify whether l-arginine supplement could alleviate this vasculotoxic effect.

METHOD

Within a mouse model of Dox injection (5 mg/kg i.p., 2 or 4 weeks), we measured vascular relaxation, blood pressure, vascular NO generation, apoptosis, and oxidative stress. We tested the efficacy of l-arginine (1.5 mg/g/day, 4 weeks) on Dox-induced vascular relaxation, blood pressure, vascular NO generation, apoptosis, as well as oxidative stress.

RESULTS

Dox induced endothelium-dependent vascular dysfunction, which was associated with increased reactive oxidative stress (ROS) production and reduced NO generation in the vessel. ROS was required for Dox-induced apoptosis of both smooth muscle cells and endothelial cells. Dox treatment in mice increased blood pressure, but had no effect on vascular inflammation and fibrosis. L-aringine restored Dox-induced vascular dysfunction via enhancing vascular NO production and alleviating ROS-mediated apoptosis.

CONCLUSION

We for the first time demonstrated l-arginine was effectively in suppressing Dox-induced vascular dysfunction, by attenuating vascular NO release and apoptosis. Our results provide a therapeutic target or a circulating marker for assessing vascular dysfunction which response to Dox treatment, and advance our understanding of the mechanisms of Dox-induced vascular dysfunction.

Clinical and preclinical evidence of sex-related differences in anthracycline-induced cardiotoxicity

Anthracyclines are very effective chemotherapeutic agents that are widely used to treat pediatric and adult cancer patients. Unfortunately, the clinical utility of anthracyclines is limited by cardiotoxicity. There are several established risk factors for anthracycline-induced cardiotoxicity (AIC), including total cumulative dose, very young and very old age, concomitant use of other cardiotoxic agents, and concurrent mediastinal radiation. However, the role of sex as a risk factor for AIC is not well defined. In pediatric cancer patients, most studies support the notion that female sex is a significant risk factor for AIC. Conversely, there is anecdotal evidence that female sex protects against AIC in adult cancer patients. The lack of consistency in study designs and the different definitions of cardiotoxicity preclude reaching consensus regarding the role of sex as a risk factor for AIC in both pediatric and adult cancer patients. Therefore, more clinical research using reliable techniques such as cardiac magnetic resonance imaging is needed to determine if there truly are sex differences in AIC. In adult preclinical rodent studies, however, there is unequivocal evidence that female sex confers significant protection against AIC, with a possible protective effect of female sex hormones and/or a detrimental role of the male sex hormones. Although findings of these rodent studies may not perfectly mirror the clinical scenario in adult anthracycline-treated cancer patients, understanding the mechanisms of this significant sexual dimorphism may reveal important cardioprotective mechanisms that can be therapeutically targeted.

Aerobic Exercise During Early Murine Doxorubicin Exposure Mitigates Cardiac Toxicity

We report the cardioprotective effects of moderate aerobic exercise from parallel pediatric murine models of doxorubicin (Doxo) exposure in non-tumor-bearing immune competent (NTB-IC) mice and tumor-bearing nude mice (TB-NM). In both models, animals at 4 weeks of age underwent Doxo treatment with or without 2 weeks of simultaneous exercise. In sedentary NTB-IC or TB-NM mice, Doxo treatment resulted in a statistically significant decrease in ejection fraction and fractional shortening compared with control animals. Interestingly, moderate aerobic exercise during Doxo treatment significantly mitigated decreases in ejection fraction and fractional shortening. In contrast, these protective effects of exercise were not observed when exercise was started after completion of Doxo treatments. Moreover, in the TB-NM model, Doxo caused a decrease in heart mass: tibia length and in body weight that was prevented by exercise, whereas NTB-IC mice exhibited no change in these measurements. Doxo delivery to the hearts of TB-NM was decreased by consistent moderate aerobic exercise before Doxo injection. These findings demonstrate the important but subtle differences in cardiotoxicity observed in different mouse models. Collectively, these results also strongly suggest that aerobic exercise during early-life Doxo exposure mitigates cardiotoxicity, possibly through altered delivery of Doxo to myocardial tissue.

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.

Creatine Supplementation and Doxorubicin-Induced Skeletal Muscle Dysfunction: An Ex Vivo Investigation

Supplementing the diet with creatine (Cr) to manage chemotherapy-induced skeletal muscle weakness and fatigue has potential, but little has been done exploring it as an intervention. This study examined the effects of Cr on skeletal muscle dysfunction induced by the chemotherapy drug doxorubicin (Dox). Soleus and extensor digitorum longus (EDL) from male Sprague-Dawley rats maintained in an organ bath were incubated in Krebs-Henseleit (KH) buffer with or without creatine monohydrate (25 mM) for 30 min. Skeletal muscle was then incubated in KH buffer with or without Dox (24 μM) for an additional 30 min. Baths were then refreshed with KH buffer, and a 100-s fatigue protocol was administered. At baseline (0 s time point), no significant differences in force production were observed in the slow, type I soleus, but the Dox-treated soleus fatigued quicker than the non-Dox-treated soleus; however, pretreatment with Cr extended the time to fatigue in the Dox-treated soleus. In the fast, type II EDL, Dox treatment decreased force production at baseline and increased fatigue, and Cr treatment prior to Dox attenuated this dysfunction. Creatine pretreatment mitigated Dox-induced skeletal muscle dysfunction ex vivo suggesting that Cr may play a role in managing Dox-induced skeletal muscle side effects.

Aerobic exercise in anthracycline-induced cardiotoxicity: a systematic review of current evidence and future directions

Cancer and cardiovascular disease are major causes of morbidity and mortality worldwide. Older cancer patients often wrestle with underlying heart disease during cancer therapy, whereas childhood cancer survivors are living long enough to face long-term unintended cardiac consequences of cancer therapies, including anthracyclines. Although effective and widely used, particularly in the pediatric population, anthracycline-related side effects including dose-dependent association with cardiac dysfunction limit their usage. Currently, there is only one United States Food and Drug Administration-approved drug, dexrazoxane, available for the prevention and mitigation of cardiotoxicity related to anthracycline therapy. While aerobic exercise has been shown to reduce cardiovascular complications in multiple diseases, its role as a therapeutic approach to mitigate cardiovascular consequences of cancer therapy is in its infancy. This systematic review aims to summarize how aerobic exercise can help to alleviate unintended cardiotoxic side effects and identify gaps in need of further research. While published work supports the benefits of aerobic exercise, additional clinical investigations are warranted to determine the effects of different exercise modalities, timing, and duration to identify optimal aerobic training regimens for reducing cardiovascular complications, particularly late cardiac effects, in cancer survivors exposed to anthracyclines.

EXercise to prevent AnthrCycline-based Cardio-Toxicity (EXACT) in individuals with breast or hematological cancers: a feasibility study protocol

BACKGROUND

Anthracyclines (AC), widely used and effective anticancer agents, are known to induce both acute and chronic declines in cardiovascular health, ranging in severity from asymptomatic, subclinical dysfunction to substantial cardiomyopathy leading to congestive heart failure and death. There is substantial evidence that physical activity, higher levels of cardiorespiratory fitness, and exercise therapy can help prevent cardiovascular disease. Moreover, animal studies have shown that exercise performed concomitantly with AC treatment may attenuate early cardiac damage that results from AC exposure. Our primary objective is to assess the feasibility of a 12-week aerobic exercise training (AET) program in patients receiving AC-based chemotherapy.

METHODS/DESIGN

This is a prospective, single-arm (pre-post-test design), feasibility study of a supervised 12-week progressive, light-to-moderate to moderate-to-vigorous intensity AET program for patients (18-65 years) receiving AC chemotherapeutic treatment for a primary/non-recurrent breast cancer or hematological malignancy. Both feasibility (e.g., participant recruitment, program adherence, safety) and intervention outcome (e.g., biological markers of cardiotoxicity, aerobic capacity, quality of life) measures will be collected. The AET program will include two, 45-min community-based exercise sessions (treadmill or cycle) per week for a total of 12 weeks. All exercise sessions will be supervised by trained exercise specialists.

DISCUSSION

Data from the EXACT study will be evaluated to determine the need to refine patient recruitment methods and general acceptability of the AET program. Preliminary data on the effects of the AET intervention on pertinent cardiac and health outcomes will also be evaluated and used to inform future studies in terms of the most appropriate outcome measure(s) to adopt and sample size estimation.

TRIAL REGISTRATION

ClinicalTrails.gov, NCT02471053.

Cardiotoxicity of anthracycline therapy: current perspectives

Anthracyclines, especially doxorubicin and daunorubicin, are the drugs of first choice in the treatment of patients with hematologic malignancies, soft-tissue sarcomas, and solid tumors. Unfortunately, the use of anthracyclines is limited by their dose-dependent and cumulative cardiotoxicity. The molecular mechanism responsible for anthracycline-induced cardiotoxicity remains poorly understood, although experimental and clinical studies have shown that oxidative stress plays the main role. Hence, antioxidant agents, especially dexrazoxane, and also other drug classes (statins, β-blockers) proved to have a beneficial effect in protecting against anthracycline-induced cardiotoxicity. According to previous clinical trials, the major high-risk factors for anthracycline-induced cardiotoxicity are age, body weight, female gender, radiotherapy, and other diseases such as Down syndrome, familial dilated cardiomyopathy, diabetes and hypertension. Consequently, further studies are needed to elucidate the molecular pathogenesis of anthracycline-induced cardiotoxicity and also to discover new cardioprotective agents against anthracycline-induced cardiotoxicity.

Exercise training does not affect anthracycline antitumor efficacy while attenuating cardiac dysfunction

Highly effective anthracyclines, like doxorubicin (DOX), have limited clinical use due to protracted cardiotoxic effects. While exercise is known to be cardioprotective, it is unclear whether exercise compromises chemotherapy treatment efficacy. To determine the effect of exercise training on DOX antitumor efficacy as well as DOX-induced cardiotoxicity, female Fisher 344 rats were randomly assigned to sedentary + saline (SED+SAL), SED+DOX, wheel run exercise training + SAL (WR+SAL), or WR+DOX. On week 11, animals were inoculated with 1×10(6) MatBIII tumor cells. Once tumors reached ∼1 cm in diameter, animals were treated with 12 mg/kg of DOX or SAL. Animals were killed 1, 3, or 5 days following treatment. Tumor growth and cardiac function were measured at each interval. DOX accumulation and multidrug resistance protein (MRP) expression were quantified in tumor and heart tissue. No significant difference (P > 0.05) existed between DOX-treated SED and WR groups for tumor measurements. Exercise preserved cardiac function up to 5 days following DOX treatment. Exercise reduced ventricular DOX accumulation and upregulated ventricular MPR1 and MPR2. In contrast, no differences were observed in DOX accumulation or MRP expression in tumors of SED and WR animals. Endurance exercise had no effect on DOX antitumor efficacy as evidenced by a definitive DOX-induced reduction in tumor growth in both the SED and WR groups. Although exercise did not affect the antitumor efficacy of DOX, it still provided protection against cardiac dysfunction. These effects may be mediated by the degree of DOX tissue accumulation secondary to the regulation of MRP expression.

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.

Concomitant low-dose doxorubicin treatment and exercise

Cardiotoxicity is a side effect for cancer patients treated with doxorubicin (DOX). We tested the hypothesis that low-intensity aerobic exercise concomitant with DOX treatment would offset DOX-induced cardiotoxicity while also improving the therapeutic efficacy of DOX on tumor progression. B16F10 melanoma cells (3 × 10(5)) were injected subcutaneously into the scruff of 6- to 8-wk-old male C57BL/6 mice (n = 48). A 4 mg/kg cumulative dose of DOX was administered over 2 wk, and exercise (EX) consisted of treadmill walking (10 m/min, 45 min/day, 5 days/wk, 2 wk). Four experimental groups were tested: 1) sedentary (SED) + vehicle, 2) SED + DOX, 3) EX + vehicle, and 4) EX + DOX. Tumor volume was attenuated in DOX and lowest in EX + DOX. DOX-treated animals had less gain in body weight, reduced heart weights (HW), smaller HW-to-body weight ratios, and shorter tibial lengths by the end of the protocol; and exercise did not reverse the cardiotoxic effects of DOX. Despite decreased left ventricular (LV) mass with DOX, cardiomyocyte cross-sectional area, β-myosin heavy chain gene expression, and whole heart systolic (fractional shortening) and diastolic (E/A ratio) function were similar among groups. DOX also resulted in increased LV fibrosis with lower LV end diastolic volume and stroke volume. Myocardial protein kinase B activity was increased with both DOX and EX treatments, and tuberous sclerosis 2 (TSC2) abundance was reduced with EX. Downstream phosphorylation of TSC2 and mammalian target of rapamycin were similar across groups. We conclude that exercise increases the efficacy of DOX in inhibiting tumor growth without mitigating subclinical DOX-induced cardiotoxicity in a murine model of melanoma.

Doxorubicin-induced vascular dysfunction and its attenuation by exercise preconditioning

Doxorubicin (DOX) is a highly effective anthracycline antibiotic used to treat a wide array of cancers. Its use is limited because of dose-dependent cardiovascular toxicity. Although exercise training has been shown to protect against DOX-induced cardiotoxicity, it is unclear as to whether exercise can attenuate DOX-induced vascular dysfunction. The purpose of this study was to determine if exercise training provides protection against the deleterious vascular effects of DOX treatment and if any changes in vascular function are related to the accumulation of DOX in vascular tissue. Male Sprague-Dawley rats remained sedentary (SED) or engaged in 14 weeks of voluntary wheel running (WR). After the 14-week period, animals received 15 mg DOX per kilogram of body mass or an equivalent volume of saline. Twenty-four hours after DOX/saline exposure, the aorta was isolated and was used to examine vascular function and aortic DOX accumulation. Aortic rings from WR + DOX animals contracted with significantly greater force and showed improved endothelium-independent relaxation when compared with rings from SED + DOX animals. In contrast, no significant differences in endothelium-dependent aortic function were noted between WR + DOX and SED + DOX. Furthermore, no significant differences in aortic DOX accumulation were observed between the DOX groups. These results suggest that chronic exercise attenuates vascular smooth muscle dysfunction associated with DOX treatment and seems to be independent of DOX accumulation in vascular tissue.

Exercise mitigates cardiac doxorubicin accumulation and preserves function in the rat

PURPOSE

Doxorubicin (DOX) is an effective antineoplastic agent with well-characterized cardiotoxic effects. Although exercise has been shown to protect against DOX cardiotoxicity, a clear and concise mechanism to explain its cardioprotective effects is lacking. The purpose of this study was to determine if exercise training reduces cardiac DOX accumulation, thereby providing a possible mechanism to explain the cardioprotective effects of exercise against DOX toxicity.

METHODS

Sprague-Dawley rats were randomly assigned to 1 of 3 primary experimental groups: sedentary (n = 77), wheel running (n = 65), or treadmill (n = 65). Animals in wheel running and treadmill groups completed 10 weeks of exercise before DOX treatment. DOX was administered 24 hours after the last training session as a bolus intraperitoneal injection at 10 mg/kg. Subgroups of rats from each primary group were killed at 1, 3, 5, 7, and 9 days after DOX exposure to assess cardiac function and DOX accumulation.

RESULTS

Ten weeks of exercise preconditioning reduced myocardial DOX accumulation, and this reduction in accumulation was associated with preserved cardiac function.

CONCLUSIONS

These data suggest that the cardioprotective effects of exercise against DOX-induced injury may be due, in part, to a reduction in myocardial DOX accumulation.

Voluntary wheel running in growing rats does not protect against doxorubicin-induced osteopenia

There is growing concern regarding the long-term negative side effects of chemotherapy in childhood cancer survivors. Doxorubicin (DOX) is commonly used in the treatment of childhood cancers and has been shown to be both cardiotoxic and osteotoxic. It is unclear whether exercise can attenuate the negative skeletal effects of this chemotherapy. Rat pups were treated with saline or DOX. Animals remained sedentary or voluntarily exercised. After 10 weeks, femoral bone mineral content and bone mineral density were measured using dual-energy x-ray absorptiometry. Cortical and cancellous bone architecture was then evaluated by microcomputed tomography. DOX had a profound negative effect on all measures of bone mass and cortical and cancellous bone architecture. Treatment with DOX resulted in shorter femora and lower femoral bone mineral content and bone mineral density, lower cross-sectional volume, cortical volume, marrow volume, cortical thickness, and principal (IMAX, IMIN) and polar (IPOLAR) moments of inertia in the femur diaphysis, and lower cancellous bone volume/tissue volume, trabecular number, and trabecular thickness in the distal femur metaphysis. Exercise failed to protect bones from the damaging effects of DOX. Other modalities may be necessary to mitigate the deleterious skeletal effects that occur in juveniles undergoing treatment with anthracyclines.

Tissue retention of doxorubicin and its effects on cardiac, smooth, and skeletal muscle function

Cancer-related fatigue is a pervasive syndrome experienced by a majority of cancer patients undergoing treatment, and muscular dysfunction may be a key component in the development and progression of this syndrome. Doxorubicin (DOX) is a commonly used antineoplastic agent used in the treatment of many cancers. The purpose of this study was to determine the effect of DOX exposure on the function of cardiac, skeletal, and smooth muscle tissues and examine the role accumulation of DOX may play in this process. In these studies, rats were treated with DOX and measurements of cardiac, skeletal, and smooth muscle function were assessed 1, 3, and 5 days after exposure. All muscular tissues showed significant and severe dysfunction, yet there was heterogeneity both in the time course of dysfunction and in the accumulation of DOX. Cardiac and skeletal muscle exhibited a time-dependent progressive decline in function during the 5 days following DOX treatment. In contrast, vascular function showed a decline in function that could be characterized as rapid onset and was sustained for the duration of the 5-day observation period. DOX accumulation was greatest in cardiac tissue, yet all muscular tissues showed a similar degree of dysfunction. Our data suggest that in muscular tissues both DOX-dependent and DOX-independent mechanisms may be involved with the muscular dysfunction observed following DOX treatment. Furthermore, this study highlights the fact that dysfunction of skeletal and smooth muscle may be an underappreciated aspect of DOX toxicity and may be a key component of cancer-related fatigue in these patients.