Role of mtDNA lesions in anthracycline cardiotoxicity

Mitochondrial DNA damage, repair, and replacement in cancer

Mitochondria are vital organelles with their own DNA (mtDNA). mtDNA is circular and composed of heavy and light chains that are structurally more accessible than nuclear DNA (nDNA). While nDNA is typically diploid, the number of mtDNA copies per cell is higher and varies considerably during development and between tissues. Compared with nDNA, mtDNA is more prone to damage that is positively linked to many diseases, including cancer. Similar to nDNA, mtDNA undergoes repair processes, although these mechanisms are less well understood. In this review, we discuss the various forms of mtDNA damage and repair and their association with cancer initiation and progression. We also propose horizontal mitochondrial transfer as a novel mechanism for replacing damaged mtDNA.

The Role of Nrf2 and Inflammation on the Dissimilar Cardiotoxicity of Doxorubicin in Two-Time Points: a Cardio-Oncology In Vivo Study Through Time

Doxorubicin (DOX) is a topoisomerase II inhibitor used in cancer therapy. Despite its efficacy, DOX causes serious adverse effects, such as short- and long-term cardiotoxicity. This work aimed to assess the short- and long-term cardiotoxicity of DOX and the role of inflammation and antioxidant defenses on that cardiotoxicity in a mice model. Adult CD-1 male mice received a cumulative dose of 9.0 mg/kg of DOX (2 biweekly intraperitoneal injections (ip), for 3 weeks). One week (1W) or 5 months (5M) after the last DOX administration, the heart was collected. One week after DOX, a significant increase in p62, tumor necrosis factor receptor (TNFR) 2, glutathione peroxidase 1, catalase, inducible nitric oxide synthase (iNOS) cardiac expression, and a trend towards an increase in interleukin (IL)-6, TNFR1, and B-cell lymphoma 2 associated X (Bax) expression was observed. Moreover, DOX induced a decrease on nuclear factor erythroid-2 related factor 2 (Nrf2) cardiac expression. In both 1W and 5M, DOX led to a high density of infiltrating M1 macrophages, but only the 1W-DOX group had a significantly higher number of nuclear factor κB (NF-κB) p65 immunopositive cells. As late effects (5M), an increase in Nrf2, myeloperoxidase, IL-33, tumor necrosis factor-α (TNF-α), superoxide dismutase 2 (SOD2) expression, and a trend towards increased catalase expression were observed. Moreover, B-cell lymphoma 2 (Bcl-2), cyclooxygenase-2 (COX-2), and carbonylated proteins expression decreased, and a trend towards decreased p38 mitogen-activated protein kinase (MAPK) expression were seen. Our study demonstrated that DOX induces adverse outcome pathways related to inflammation and oxidative stress, although activating different time-dependent response mechanisms.

Cardiotoxicity of anti-cancer drugs: cellular mechanisms and clinical implications

Cardio-oncology is an emerging field that seeks to enhance quality of life and longevity of cancer survivors. It is pertinent for clinicians to understand the cellular mechanisms of prescribed therapies, as this contributes to robust understanding of complex treatments and off-target effects, improved communication with patients, and guides long term care with the goal to minimise or prevent cardiovascular complications. Our aim is to review the cellular mechanisms of cardiotoxicity involved in commonly used anti-cancer treatments and identify gaps in literature and strategies to mitigate cardiotoxicity effects and guide future research endeavours.

Revisiting treatment-related cardiotoxicity in patients with malignant lymphoma-a review and prospects for the future

Treatment of malignant lymphoma has for years been represented by many cardiotoxic agents especially anthracyclines, cyclophosphamide, and thoracic irradiation. Although they are in clinical practice for decades, the precise mechanism of cardiotoxicity and effective prevention is still part of the research. At this article we discuss most routinely used anti-cancer drugs in chemotherapeutic regiments for malignant lymphoma with the focus on novel insight on molecular mechanisms of cardiotoxicity. Understanding toxicity at molecular levels may unveil possible targets of cardioprotective supportive therapy or optimization of current therapeutic protocols. Additionally, we review novel specific targeted therapy and its challenges in cardio-oncology.

EPAC1 inhibition protects the heart from doxorubicin-induced toxicity

Anthracyclines, such as doxorubicin (Dox), are widely used chemotherapeutic agents for the treatment of solid tumors and hematologic malignancies. However, they frequently induce cardiotoxicity leading to dilated cardiomyopathy and heart failure. This study sought to investigate the role of the exchange protein directly activated by cAMP (EPAC) in Dox-induced cardiotoxicity and the potential cardioprotective effects of EPAC inhibition. We show that Dox induces DNA damage and cardiomyocyte cell death with apoptotic features. Dox also led to an increase in both cAMP concentration and EPAC1 activity. The pharmacological inhibition of EPAC1 (with CE3F4) but not EPAC2 alleviated the whole Dox-induced pattern of alterations. When administered in vivo, Dox-treated WT mice developed a dilated cardiomyopathy which was totally prevented in EPAC1 knock-out (KO) mice. Moreover, EPAC1 inhibition potentiated Dox-induced cell death in several human cancer cell lines. Thus, EPAC1 inhibition appears as a potential therapeutic strategy to limit Dox-induced cardiomyopathy without interfering with its antitumoral activity.

The beneficial role of exercise in preventing doxorubicin-induced cardiotoxicity

Doxorubicin is a highly effective chemotherapeutic agent widely used to treat a variety of cancers. However, the clinical application of doxorubicin is limited due to its adverse effects on several tissues. One of the most serious side effects of doxorubicin is cardiotoxicity, which results in life-threatening heart damage, leading to reduced cancer treatment success and survival rate. Doxorubicin-induced cardiotoxicity results from cellular toxicity, including increased oxidative stress, apoptosis, and activated proteolytic systems. Exercise training has emerged as a non-pharmacological intervention to prevent cardiotoxicity during and after chemotherapy. Exercise training stimulates numerous physiological adaptations in the heart that promote cardioprotective effects against doxorubicin-induced cardiotoxicity. Understanding the mechanisms responsible for exercise-induced cardioprotection is important to develop therapeutic approaches for cancer patients and survivors. In this report, we review the cardiotoxic effects of doxorubicin and discuss the current understanding of exercise-induced cardioprotection in hearts from doxorubicin-treated animals.

A Comprehensive Review of Dilated Cardiomyopathy in Pre-clinical Animal Models in Addition to Herbal Treatment Options and Multi-modality Imaging Strategies

Dilated cardiomyopathy (DCM) is distinguished by ventricular chamber expansion, systolic dysfunction, and normal left ventricular (LV) wall thickness, and is mainly caused due to genetic or environmental factors; however, its aetiology is undetermined in the majority of patients. The focus of this work is on pathogenesis, small animal models, as well as the herbal medicinal approach, and the most recent advances in imaging modalities for patients with dilated cardiomyopathy. Several small animal models have been proposed over the last few years to mimic various pathomechanisms that contribute to dilated cardiomyopathy. Surgical procedures, gene mutations, and drug therapies are all characteristic features of these models. The pros and cons, including heart failure stimulation of extensively established small animal models for dilated cardiomyopathy, are illustrated, as these models tend to procure key insights and contribute to the development of innovative treatment techniques for patients. Traditional medicinal plants used as treatment in these models are also discussed, along with contemporary developments in herbal therapies. In the last few decades, accurate diagnosis, proper recognition of the underlying disease, specific risk stratification, and forecasting of clinical outcome, have indeed improved the health of DCM patients. Cardiac magnetic resonance (CMR) is the bullion criterion for assessing ventricular volume and ejection fraction in a reliable and consistent direction. Other technologies, like strain analysis and 3D echocardiography, have enhanced this technique's predictive and therapeutic potential. Nuclear imaging potentially helps doctors pinpoint the causative factors of left ventricular dysfunction, as with cardiac sarcoidosis and amyloidosis.

Current Status and Trends of Research on Anthracycline-Induced Cardiotoxicity from 2002 to 2021: A Twenty-Year Bibliometric and Visualization Analysis

Anthracyclines constitute the cornerstone of numerous chemotherapy regimens for various cancers. However, the clinical application of anthracyclines is significantly limited to their dose-dependent cardiotoxicity. A comprehensive understanding of the current status of anthracycline-induced cardiotoxicity is necessary for in-depth research and optimal clinical protocols. Bibliometric analysis is widely applied in depicting development trends and tracking frontiers of a specific field. The present study is aimed at revealing the status and trends of anthracycline-induced cardiotoxicity during the past two decades by employing bibliometric software including R-bibliometric, VOSviewer, and CiteSpace. A total of 3504 publications concerning anthracycline-induced cardiotoxicity from 2002 to 2021 were collected from the Web of Science Core Collection database. Results showed significant growth in annual yields from 90 records in 2002 to 304 papers in 2021. The United States was the most productive country with the strongest collaboration worldwide in the field. Charles University in the Czech Republic was the institution that contributed the most papers, while 7 of the top 10 productive institutions were from the United States. The United States Department of Health and Human Services and the National Institutes of Health are the two agencies that provide financial support for more than 50% of sponsored publications. The research categories of included publications mainly belong to Oncology and Cardiac Cardiovascular Systems. The Journal of Clinical Oncology had a comprehensive impact on this research field with the highest IF value and many publications. Simunek Tomas from Charles University contributed the most publications, while Lipshultz Steven E. from the State University of New York possessed the highest H-index. In addition, the future research frontiers of anthracycline-induced cardiotoxicity might include early detection, pharmacogenomics, molecular mechanism, and cardiooncology. The present bibliometric analysis may provide a valuable reference for researchers and practitioners in future research directions.

Saponins and their derivatives: Potential candidates to alleviate anthracycline-induced cardiotoxicity and multidrug resistance

Anthracyclines (ANTs) continue to play an irreplaceable role in oncology treatment. However, the clinical application of ANTs has been limited. In the first place, ANTs can cause dose-dependent cardiotoxicity such as arrhythmia, cardiomyopathy, and congestive heart failure. In the second place, the development of multidrug resistance (MDR) leads to their chemotherapeutic failure. Oncology cardiologists are urgently searching for agents that can both protect the heart and reverse MDR without compromising the antitumor effects of ANTs. Based on in vivo and in vitro data, we found that natural compounds, including saponins, may be active agents for other both natural and chemical compounds in the inhibition of anthracycline-induced cardiotoxicity (AIC) and the reversal of MDR. In this review, we summarize the work of previous researchers, describe the mechanisms of AIC and MDR, and focus on revealing the pharmacological effects and potential molecular targets of saponins and their derivatives in the inhibition of AIC and the reversal of MDR, aiming to encourage future research and clinical trials.

Beyond hypertension: Diastolic dysfunction associated with cancer treatment in the era of cardio-oncology

Cancer patients are at an increased risk of cardiovascular events. Both old-generation cytostatics/cytotoxics and new-generation "targeted" drugs can in fact damage cardiomyocytes, endothelial cells of veins and arteries, specialized cells of the conduction system, pericardium, and valves. A new discipline, cardio-oncology, has therefore developed with the aim of protecting cancer patients from cardiovascular events, while also providing them with the best possible oncologic treatment. Anthracyclines have long been known to elicit cardiotoxicity that, depending on treatment- or patient-related factors, may progress with a variable velocity toward cardiomyopathy and systolic heart failure. However, early compromise of diastolic function may precede systolic dysfunction, and a progression of early diastolic dysfunction to diastolic rather than systolic heart failure has been documented in long-term cancer survivors. This chapter first describes general notions about hypertension in the cancer patient and then moves on reviewing the pathophysiology and clinical trajectories of diastolic dysfunction, and the molecular mechanisms of anthracycline-induced diastolic dysfunction. Diastolic dysfunction can in fact be caused and/or aggravated by hypertension. Pharmacologic foundations and therapeutic opportunities to prevent or treat diastolic dysfunction before it progresses toward heart failure are also reviewed, with a special emphasis on the mechanisms of action of drugs that raised hopes to treat diastolic dysfunction in the general population (sacubitril/valsartan, guanylyl cyclase activators, phosphodiesterase inhibitors, ranolazine, inhibitors of type-2 sodium-glucose-inked transporter). Cardio-oncologists will be confronted with the risk:benefit ratio of using these drugs in the cancer patient.

Major vault protein attenuates cardiomyocyte injury in doxorubicin-induced cardiomyopathy through activating AKT

Background

Doxorubicin (DOX) has limited chemotherapy application for malignancies due to cardiotoxicity. The pathogenesis of DOX-induced cardiomyopathy (DiCM) is yet to be elucidated. Increasing studies proved that activation of AKT prevented cardiomyocyte apoptosis and cardiac dysfunction in response to DOX insult. Our previous studies indicated that major vault protein (MVP) deficiency was accompanied by suppressed phosphorylation of AKT in metabolic diseases. This study aimed to investigate the role and underlying mechanism of MVP on cardiomyocyte apoptosis in DiCM.

Methods

Mice were intraperitoneally injected with DOX 5 mg/kg, once a week for 5 weeks, the total cumulative dose was 25 mg/kg. Cardiomyocyte-specific MVP overexpression was achieved using an adeno-associated virus system under the cTnT promoter after the fourth DOX injection. Cardiac function was examined by echocardiography followed by euthanasia. Tissue and serum were collected for morphology analysis and biochemical examination.

Results

Herein, we found that MVP expression was upregulated in DOX-treated murine hearts. Cardiac-specific MVP overexpression alleviated DOX-induced cardiac dysfunction, oxidative stress and fibrosis. Mechanistically, MVP overexpression activated AKT signaling and decreased cardiomyocyte apoptosis in DiCM.

Conclusions

Based on these findings, we supposed that MVP was a potential therapeutic agent against DiCM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02517-9.

Cardiotoxicity in pediatric lymphoma survivors

INTRODUCTION

Over the past five decades, the diagnosis and management of children with various malignancies have improved tremendously. As a result, an increasing number of children are long-term cancer survivors. With improved survival, however, has come an increased risk of treatment-related cardiovascular complications that can appear decades later.

AREAS COVERED

This review discusses the pathophysiology, epidemiology and effects of treatment-related cardiovascular complications from anthracyclines and radiotherapy in pediatric lymphoma survivors. There is a paucity of evidence-based recommendations for screening for and treatment of cancer therapy-induced cardiovascular complications. We discuss current preventive measures and strategies for their treatment.

EXPERT OPINION

Significant cardiac adverse effects occur due to radiation and chemotherapy received by patients treated for lymphoma. Higher lifetime cumulative doses, female sex, longer follow-up, younger age, and preexisting cardiovascular disease are associated with a higher incidence of cardiotoxicity. With deeper understanding of the mechanisms of these adverse cardiac effects and identification of driver mutations causing these effects, personalized cancer therapy to limit cardiotoxic effects while ensuring an adequate anti-neoplastic effect would be ideal. In the meantime, expanding the use of cardioprotective agents with the best evidence such as dexrazoxane should be encouraged and further studied.

Instability in NAD+ metabolism leads to impaired cardiac mitochondrial function and communication

Poly(ADP-ribose) polymerase (PARP) enzymes initiate (mt)DNA repair mechanisms and use nicotinamide adenine dinucleotide (NAD⁺) as energy source. Prolonged PARP activity can drain cellular NAD⁺ reserves, leading to de-regulation of important molecular processes. Here, we provide evidence of a pathophysiological mechanism that connects mtDNA damage to cardiac dysfunction via reduced NAD⁺ levels and loss of mitochondrial function and communication. Using a transgenic model, we demonstrate that high levels of mice cardiomyocyte mtDNA damage cause a reduction in NAD⁺ levels due to extreme DNA repair activity, causing impaired activation of NAD⁺-dependent SIRT3. In addition, we show that myocardial mtDNA damage in combination with high dosages of nicotinamideriboside (NR) causes an inhibition of sirtuin activity due to accumulation of nicotinamide (NAM), in addition to irregular cardiac mitochondrial morphology. Consequently, high doses of NR should be used with caution, especially when cardiomyopathic symptoms are caused by mitochondrial dysfunction and instability of mtDNA.

Oxidative stress and inflammation: determinants of anthracycline cardiotoxicity and possible therapeutic targets

Chemotherapy with anthracycline-based regimens remains a cornerstone of treatment of many solid and blood tumors but is associated with a significant risk of cardiotoxicity, which can manifest as asymptomatic left ventricular dysfunction or overt heart failure. These effects are typically dose-dependent and cumulative and may require appropriate screening strategies and cardioprotective therapies in order to minimize changes to anticancer regimens or even their discontinuation. Our current understanding of cardiac damage by anthracyclines includes a central role of oxidative stress and inflammation. The identification of these processes through circulating biomarkers or imaging techniques might then be helpful for early diagnosis and risk stratification. Furthermore, therapeutic strategies relieving oxidative stress and inflammation hold promise to prevent heart failure development or at least to mitigate cardiac damage, although further evidence is needed on their efficacy, either alone or as part of combination therapies with neurohormonal antagonists, which are the current adopted standard.

The implications of mitochondria in doxorubicin treatment of cancer in the context of traditional and modern medicine

Doxorubicin (DOX) is an antibiotic anthracycline extensively used in the treatment of different malignancies, such as breast cancer, lymphomas and leukemias. The cardiotoxicity induced by DOX is one of the most important pathophysiological events that limit its clinical application. Accumulating evidence highlights mitochondria as a central role in this process. Modulation of mitochondrial functions as therapeutic strategy for DOX-induced cardiotoxicity has thus attracted much attention. In particular, emerging studies investigated the potential of natural mitochondria-targeting compounds from Traditional Chinese Medicine (TCM) as adjunct or alternative treatment for DOX-induced toxicity. This review summarizes studies about the mechanisms of DOX-induced cardiotoxicity, evidencing the importance of mitochondria and presenting TCM treatment alternatives for DOX-induced cardiomyopathy.

Molecular mechanisms of anthracycline cardiovascular toxicity

Anthracyclines are effective chemotherapeutic agents, commonly used in the treatment of a variety of hematologic malignancies and solid tumors. However, their use is associated with a significant risk of cardiovascular toxicities and may result in cardiomyopathy and heart failure. Cardiomyocyte toxicity occurs via multiple molecular mechanisms, including topoisomerase II-mediated DNA double-strand breaks and reactive oxygen species (ROS) formation via effects on the mitochondrial electron transport chain, NADPH oxidases (NOXs), and nitric oxide synthases (NOSs). Excess ROS may cause mitochondrial dysfunction, endoplasmic reticulum stress, calcium release, and DNA damage, which may result in cardiomyocyte dysfunction or cell death. These pathophysiologic mechanisms cause tissue-level manifestations, including characteristic histopathologic changes (myocyte vacuolization, myofibrillar loss, and cell death), atrophy and fibrosis, and organ-level manifestations including cardiac contractile dysfunction and vascular dysfunction. In addition, these mechanisms are relevant to current and emerging strategies to diagnose, prevent, and treat anthracycline-induced cardiomyopathy. This review details the established and emerging data regarding the molecular mechanisms of anthracycline-induced cardiovascular toxicity.

Genetics of Anthracycline Cardiomyopathy in Cancer Survivors: JACC: CardioOncology State-of-the-Art Review

Anthracyclines are an integral part of chemotherapy regimens used to treat a variety of childhood-onset and adult-onset cancers. However, the development of cardiac dysfunction and heart failure often compromises the clinical utility of anthracyclines. The risk of cardiac dysfunction increases with anthracycline dose. This anthracycline-cardiac dysfunction association is modified by several demographic and clinical factors, such as age at anthracycline exposure (<4 years and ≥65 years); female sex; chest radiation; presence of cardiovascular risk factors (diabetes, hypertension); and concurrent use of cyclophosphamide, paclitaxel, and trastuzumab. However, the clinical variables alone yield modest predictive power in detecting cardiac dysfunction. Recently, attention has focused on the molecular basis of anthracycline-related cardiac dysfunction, providing an initial understanding of the mechanism of anthracycline-related cardiomyopathy. This review describes the current state of knowledge with respect to the pathogenesis of anthracycline-related cardiomyopathy and identifies the critical next steps to mitigate this problem.

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Anthracycline chemotherapy results in an increased risk of cardiac dysfunction.

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Most recent studies have suggested that there is a genetic basis for anthracycline-related cardiac dysfunction.

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Integration of genetics with the clinical characteristics may be used to enhance the ability to predict the risk for anthracycline-related cardiomyopathy.

Cardiac Damage in Anthracyclines Therapy: Focus on Oxidative Stress and Inflammation

Significance: Despite their serious side effects, anthracyclines (ANTs) are the most prescribed chemotherapeutic drugs because of their strong efficacy in both solid and hematological tumors. A major limitation to ANTs clinical application is the severe cardiotoxicity observed both acutely and chronically. The mechanism underlying cardiac dysfunction under chemotherapy is mainly dependent on the generation of oxidative stress and systemic inflammation, both of which lead to progressive cardiomyopathy and heart failure. Recent Advances: Over the years, the iatrogenic ANTs-induced cardiotoxicity was believed to be simply given by iron metabolism and reactive oxygen species production; however, several experimental data indicate that ANTs may use alternative damaging mechanisms, such as topoisomerase 2β inhibition, inflammation, pyroptosis, immunometabolism, and autophagy. Critical Issues: In this review, we aimed at discussing ANTs-induced cardiac injury from different points of view, updating and focusing on oxidative stress and inflammation, since these pathways are not exclusive or independent from each other but they together importantly contribute to the complexity of ANTs-induced multifactorial cardiotoxicity. Future Directions: A deeper understanding of the mechanistic signaling leading to ANTs side effects could reveal crucial targeting molecules, thus representing strategic knowledge to promote better therapeutic efficacy and lower cardiotoxicity during clinical application.

Utilizing Synergistic Potential of Mitochondria-Targeting Drugs for Leukemia Therapy

Acute myeloid leukemia (AML) is an aggressive group of cancers with high mortality rates and significant relapse risks. Current treatments are insufficient, and new therapies are needed. Recent discoveries suggest that AML may be particularly sensitive to chemotherapeutics that target mitochondria. To further investigate this sensitivity, six compounds that target mitochondria [IACS-010759, rotenone, cytarabine, etoposide, ABT-199 (venetoclax), and carbonyl cyanide m-chlorophenylhydrazone] were each paired with six compounds with other activities, including tyrosine kinase inhibitors (midostaurin and dasatinib), glycolytic inhibitors (2-deoxy-D-glucose, 3-bromopyruvate, and lonidamine), and the microtubule destabilizer vinorelbine. The 36 resulting drug combinations were tested for synergistic cytotoxicity against MOLM-13 and OCI-AML2 AML cell lines. Four combinations (IACS-010759 with vinorelbine, rotenone with 2-deoxy-D-glucose, carbonyl cyanide m-chlorophenylhydrazone with dasatinib, and venetoclax with lonidamine) showed synergistic cytotoxicity in both AML cell lines and were selective for tumor cells, as survival of healthy PBMCs was dramatically higher. Among these drug pairs, IACS-010759/vinorelbine decreased ATP level and impaired mitochondrial respiration and coupling efficiency most profoundly. Some of these four treatments were also effective in K-562, KU812 (chronic myelogenous leukemia) and CCRF-CEM, MOLT-4 (acute lymphoblastic leukemia) cells, suggesting that these treatments may have value in treating other forms of leukemia. Finally, two of the four combinations retained high synergy and strong selectivity in primary AML cells from patient samples, supporting the potential of these treatments for patients.

Bioinformatic analysis of peripheral blood miRNA of breast cancer patients in relation with anthracycline cardiotoxicity

BACKGROUND

The current diagnostic methods and treatments still fail to lower the incidence of anthracycline-induced cardiotoxicity effectively. In this study, we aimed to (1) analyze the cardiotoxicity-related genes after breast cancer chemotherapy in gene expression database and (2) carry out bioinformatic analysis to identify cardiotoxicity-related abnormal expressions, the biomarkers of such abnormal expressions, and the key regulatory pathways after breast cancer chemotherapy.

METHODS

Cardiotoxicity-related gene expression data (GSE40447) after breast cancer chemotherapy was acquired from the Gene Expression Omnibus (GEO) database. The biomarker expression data of women with chemotherapy-induced cardiotoxicity (group A), chemotherapy history but no cardiotoxicity (group B), and confirmatory diagnosis of breast cancer but normal ejection fraction before chemotherapy (group C) were analyzed to obtain the mRNA with differential expressions and predict the micro RNAs (miRNAs) regulating the differential expressions. The miRanda formula and functional enrichment analysis were used to screen abnormal miRNAs. Then, the Gene Ontology (GO) analysis was adapted to further screen the miRNAs related to cardiotoxicity after breast cancer chemotherapy.

RESULT

The data of differential analysis of biomarker expression of groups A, B, and C using the GSE40447-related gene expression profile database showed that there were 30 intersection genes. The differentially expressed mRNAs were predicted using the miRanda and Target Scan software, and a total of 2978 miRNAs were obtained by taking the intersections. Further, the GO analysis and targeted regulatory relationship between miRNA and target genes were used to establish miRNA-gene interaction network to screen and obtain seven cardiotoxicity-related miRNAs with relatively high centrality, including hsa-miR-4638-3p, hsa-miR-5096, hsa-miR-4763-5p, hsa-miR-1273 g-3p, hsa-miR6192, hsa-miR-4726-5p and hsa-miR-1273a. Among them, hsa-miR-4638-3p and hsa-miR-1273 g-3p had the highest centrality. The PCR verification results were consistent with those of the chip data. There are differentially expressed miRNAs in the peripheral blood of breast cancer patients with anthracycline cardiotoxicity. Among them, hsa-miR-4638-3p and hsa-miR-1273 g-3p are closely associated with the onset of anthracycline cardiotoxicity in patients with breast cancer. The signaling pathway is mainly concentrated in TGF-β signaling pathway and adhesion signaling pathway.

CONCLUSIONS

Changes in expression of hsa-miR-4638-3p and hsa-miR-1273 g-3p may contribute to the detection of anthracyclines induced cardiac toxicity, and their potential function may be related to TGF-β signaling pathway and adhesion signaling pathway.

Doxorubicin-Induced Cardiomyopathy in Children

Doxorubicin-induced cardiotoxicity in childhood cancer survivors is a growing problem. The population of patients at risk for cardiovascular disease is steadily increasing, as five-year survival rates for all types of childhood cancers continue to improve. Doxorubicin affects the developing heart differently from the adult heart and in a subset of exposed patients, childhood exposure leads to late, irreversible cardiomyopathy. Notably, the prevalence of late-onset toxicity is increasing in parallel with improved survival. By the year 2020, it is estimated that there will be 500,000 childhood cancer survivors and over 50,000 of them will suffer from doxorubicin-induced cardiotoxicity. The majority of the research to-date, concentrated on childhood cancer survivors, has focused mostly on clinical outcomes through well-designed epidemiological and retrospective cohort studies. Preclinical studies have elucidated many of the cellular mechanisms that elicit acute toxicity in cardiomyocytes. However, more research is needed in the areas of early- and late-onset cardiotoxicity and more importantly improving the scientific understanding of how other cells present in the cardiac milieu are impacted by doxorubicin exposure. The overall goal of this review is to succinctly summarize the major clinical and preclinical studies focused on doxorubicin-induced cardiotoxicity. As the prevalence of patients affected by doxorubicin exposure continues to increase, it is imperative that the major gaps in existing research are identified and subsequently utilized to develop appropriate research priorities for the coming years. Well-designed preclinical research models will enhance our understanding of the pathophysiology of doxorubicin-induced cardiotoxicity and directly lead to better diagnosis, treatment, and prevention. © 2019 American Physiological Society. Compr Physiol 9:905-931, 2019.

Leveraging the Cardio-Protective and Anticancer Properties of Resveratrol in Cardio-Oncology

Cardio-oncology is a clinical/scientific discipline which aims to prevent and/or treat cardiovascular diseases in cancer patients. Although a large number of cancer treatments are known to cause cardiovascular toxicity, they are still widely used because they are highly effective. Unfortunately, therapeutic interventions to prevent and/or treat cancer treatment-induced cardiovascular toxicity have not been established yet. A major challenge for such interventions is to protect the cardiovascular system without compromising the therapeutic benefit of anticancer medications. Intriguingly, the polyphenolic natural compound resveratrol and its analogs have been shown in preclinical studies to protect against cancer treatment-induced cardiovascular toxicity. They have also been shown to possess significant anticancer properties on their own, and to enhance the anticancer effect of other cancer treatments. Thus, they hold significant promise to protect the cardiovascular system and fight the cancer at the same time. In this review, we will discuss the current knowledge regarding the cardio-protective and the anticancer properties of resveratrol and its analogs. Thereafter, we will discuss the challenges that face the clinical application of these agents. To conclude, we will highlight important gaps of knowledge and future research directions to accelerate the translation of these exciting preclinical findings to cancer patient care.

Management of Cancer Therapeutics-Related Cardiac Dysfunction

Improvements in detection and treatment of cancer have resulted in a significant increase in cancer survivors. However, cancer survivorship comes with long-term risk of adverse effects of cancer therapies, including cardiomyopathy, heart failure, arrhythmias, ischemic heart disease, atherosclerosis, thrombosis, and hypertension. There is a renewed interest in understanding the pathophysiology of cancer therapeuticserelated cardiac dysfunction. In recent years, efforts have been directed to the management of cancer therapeuticserelated cardiac dysfunction. This article discusses the pathophysiology and molecular mechanisms that contribute to cancer therapeutics-related cardiac dysfunction and presents an napproach to the evaluation and treatment of these patients.

Mitochondrial DNA repair: a novel therapeutic target for heart failure

Mitochondria play a crucial role in a variety of cellular processes ranging from energy metabolism, generation of reactive oxygen species (ROS) and Ca(2+) handling to stress responses, cell survival and death. Malfunction of the organelle may contribute to the pathogenesis of neuromuscular, cancer, premature aging and cardiovascular diseases (CVD), including myocardial ischemia, cardiomyopathy and heart failure (HF). Mitochondria contain their own genome organized into DNA-protein complexes, called "mitochondrial nucleoids," along with multiprotein machineries, which promote mitochondrial DNA (mtDNA) replication, transcription and repair. Although the mammalian organelle possesses almost all known nuclear DNA repair pathways, including base excision repair, mismatch repair and recombinational repair, the proximity of mtDNA to the main sites of ROS production and the lack of protective histones may result in increased susceptibility to various types of mtDNA damage. These include accumulation of mtDNA point mutations and/or deletions and decreased mtDNA copy number, which will impair mitochondrial function and finally, may lead to CVD including HF.

Time course of changes in oxidative stress and stress-induced proteins in cardiomyocytes exposed to doxorubicin and prevention by vitamin C

We previously reported that Vitamin C (Vit C) protects against doxorubicin (Dox)-induced cardiotoxicity by reducing oxidative stress, p38 mitogen-activated kinase (MAPK) and p53 activation and rescuing cell death in isolated adult cardiomyocytes. The pattern of activation and the role of oxidative stress as well as down-stream mechanisms for such protection remain elusive. Therefore the present study aims to analyze time-dependant generation of reactive oxygen species (ROS) and the activation of stress induced signalling pathways in cardiomyocytes treated with Dox and Vit C. The data provides further understanding of heart pathophysiology in response to Dox at the cellular level, and may help to optimize the timing of various therapeutic approaches. Cardiomyocytes isolated from adult Sprague-Dawley rats were exposed to Dox (10 μM), Vit C (25 μM), and Dox + Vit C for different time intervals up to 24 h. p38-JNK (SB203580) and p53 (pifithrin-α) inhibitors were used to determine the role of each respective signalling protein. Dox administration to cardiomyocytes increased the levels of ROS in a time-dependent manner that followed the activation of stress-induced proteins p53, p38 and JNK MAPKs, culminating in an increase in autophagy and apoptosis markers. Dox-induced increase in ROS was alleviated by Vit C adjuvant treatment at all time-points and this was also correlated with blunting of the activation of the studied signaling pathways leading to the prevention of apoptosis and preservation of cell viability. Protective effect of Vit C against the activation of stress induced proteins, autophagy and apoptosis was mainly attributed to its antioxidant properties even though blockage of p38, JNK and p53 by pharmacological inhibitors also suppressed Dox-induced apoptosis. ROS is defined as a key inducer of cardiomyocyte damage under Dox exposure; Vit C could effectively counteract all Dox-induced changes in cardiomyocytes and may potentially be used as an antioxidant adjuvant therapy to protect against Dox-induced cardiomyopathy.

Photodynamic Synergistic Effect of Pheophorbide a and Doxorubicin in Combined Treatment against Tumoral Cells

A combination of therapies to treat cancer malignancies is at the forefront of research with the aim to reduce drug doses (ultimately side effects) and diminish the possibility of resistance emergence given the multitarget strategy. With this goal in mind, in the present study, we report the combination between the chemotherapeutic drug doxorubicin (DOXO) and the photosensitizing agent pheophorbide a (PhA) to inactivate HeLa cells. Photophysical studies revealed that DOXO can quench the excited states of PhA, detracting from its photosensitizing ability. DOXO can itself photosensitize the production of singlet oxygen; however, this is largely suppressed when bound to DNA. Photodynamic treatments of cells incubated with DOXO and PhA led to different outcomes depending on the concentrations and administration protocols, ranging from antagonistic to synergic for the same concentrations. Taken together, the results indicate that an appropriate combination of DOXO with PhA and red light may produce improved cytotoxicity with a smaller dose of the chemotherapeutic drug, as a result of the different subcellular localization, targets and mode of action of the two agents.

Pathways of cardiac toxicity: comparison between chemotherapeutic drugs doxorubicin and mitoxantrone

Anthracyclines, e.g., doxorubicin (DOX), and anthracenediones, e.g., mitoxantrone (MTX), are drugs used in the chemotherapy of several cancer types, including solid and non-solid malignancies such as breast cancer, leukemia, lymphomas, and sarcomas. Although they are effective in tumor therapy, treatment with these two drugs may lead to side effects such as arrhythmia and heart failure. At the same clinically equivalent dose, MTX causes slightly reduced cardiotoxicity compared with DOX. These drugs interact with iron to generate reactive oxygen species (ROS), target topoisomerase 2 (Top2), and impair mitochondria. These are some of the mechanisms through which these drugs induce late cardiomyopathy. In this review, we compare the cardiotoxicities of these two chemotherapeutic drugs, DOX and MTX. As described here, even though they share similarities in their modes of toxicant action, DOX and MTX seem to differ in a key aspect. DOX is a more redox-interfering drug, while MTX induces energy imbalance. In addition, DOX toxicity can be explained by underlying mechanisms that include targeting of Top2 beta, mitochondrial impairment, and increases in ROS generation. These modes of action have not yet been demonstrated for MTX, and this knowledge gap needs to be filled.

The Protective Role of Phenolic Compounds Against Doxorubicin-induced Cardiotoxicity: A Comprehensive Review

Although doxorubicin (DOX) is among the most widely used anticancer agents, its clinical application is hampered owing to its cardiotoxicity. Adjuvant therapy with an antioxidant has been suggested as a promising strategy to reduce DOX-induced adverse effects. In this context, many phenolic compounds have been reported to protect against DOX-induced cardiotoxicity. The cardioprotective effects of phenolic compounds are exerted via multiple mechanisms including inhibition of reactive oxygen species generation, apoptosis, NF-κB, p53, mitochondrial dysfunction, and DNA damage. In this review, we present a summary of the in vitro, in vivo, and clinical findings on the protective mechanisms of phenolic compounds against DOX-induced cardiotoxicity.

Mitochondrial Function, Biology, and Role in Disease: A Scientific Statement From the American Heart Association

Cardiovascular disease is a major leading cause of morbidity and mortality in the United States and elsewhere. Alterations in mitochondrial function are increasingly being recognized as a contributing factor in myocardial infarction and in patients presenting with cardiomyopathy. Recent understanding of the complex interaction of the mitochondria in regulating metabolism and cell death can provide novel insight and therapeutic targets. The purpose of this statement is to better define the potential role of mitochondria in the genesis of cardiovascular disease such as ischemia and heart failure. To accomplish this, we will define the key mitochondrial processes that play a role in cardiovascular disease that are potential targets for novel therapeutic interventions. This is an exciting time in mitochondrial research. The past decade has provided novel insight into the role of mitochondria function and their importance in complex diseases. This statement will define the key roles that mitochondria play in cardiovascular physiology and disease and provide insight into how mitochondrial defects can contribute to cardiovascular disease; it will also discuss potential biomarkers of mitochondrial disease and suggest potential novel therapeutic approaches.

Sulfur Dioxide Contributes to the Cardiac and Mitochondrial Dysfunction in Rats

Epidemiological studies have demonstrated an association between sulfur dioxide (SO2) and an increase of morbidity and mortality of cardiovascular diseases, such as ischemic heart disease, heart failure, and arrhythmia. Mitochondrion is the most sensitive organelle in myocardium of animals exposed to SO2 Here we study the molecular characterization of mitochondrial dysfunction in cardiac muscles of rat after SO2 exposure. We found that the cytochrome c oxidase (COX) activity, mitochondrial membrane potential (ΔΨm), ATP contents, mitochondrial DNA (mtDNA) contents, and mRNA expression of complexes IV and V subunits encoded by mtDNA were decreased after NaHSO3 treatment in vitro or SO2 inhalation in vivo The mitochondrial dysfunctions were accompanied by depressions of co-activator of peroxisome proliferator activated receptor gamma (PGC-1α), nuclear respiratory factor 1, and mitochondrial transcription factor A (TFAM) mRNA and protein. We observed swollen mitochondria and lower amounts of cristae in hearts of rats after 3.5 mg/m(3) SO2 inhalation for 30 days. Interestingly, NaHSO3 induced mitochondrial dysfunctions marked by ΔΨm and ATP reduction could be inhibited by an antioxidant N-acetyl-L-cysteine (NALC), accompanied by the restoration of transcriptional factors expressions. The cardiac mitochondrial dysfunctions could also be alleviated by overexpression of TFAM. SO2 induced abnormal left ventricular function was restored by NALC in vivo Our findings demonstrate that SO2 induces cardiac and mitochondrial dysfunction. And inhibition of reactive oxygen species and enhancing the transcriptional network controlling mitochondrial biogenesis can mitigate the SO2-induced mitochondrial dysfunction.

Impaired mitochondrial function is abrogated by dexrazoxane in doxorubicin-treated childhood acute lymphoblastic leukemia survivors

BACKGROUND

Impaired cardiac function in doxorubicin-treated childhood cancer survivors is partly mediated by the disruption of mitochondrial energy production. Doxorubicin intercalates into mitochondrial DNA (mtDNA) and disrupts genes encoding for polypeptides that make adenosine triphosphate.

METHODS

This cross-sectional study examined mtDNA copy numbers per cell and oxidative phosphorylation (OXPHOS) in peripheral blood mononuclear cells (PBMCs) in 64 childhood survivors of high-risk acute lymphoblastic leukemia (ALL) who had been treated on Dana-Farber Cancer Institute childhood ALL protocols and had received doxorubicin alone (42%) or doxorubicin with the cardioprotectant dexrazoxane (58%). The number of mtDNA copies per cell and the OXPHOS enzyme activity of nicotinamide adenine dinucleotide dehydrogenase (complex I [CI]) and cytochrome c oxidase (complex IV [CIV]) were measured with quantitative real-time polymerase chain reaction immunoassays and thin-layer chromatography, respectively.

RESULTS

At a median follow-up of 7.8 years after treatment, the median number of mtDNA copies per cell for patients treated with doxorubicin alone (1106.3) was significantly higher than the median number for those who had also received dexrazoxane (310.5; P = .001). No significant differences were detected between the groups for CI or CIV activity.

CONCLUSIONS

Doxorubicin-treated survivors had an increased number of PBMC mtDNA copies per cell, and concomitant use of dexrazoxane was associated with a lower number of mtDNA copies per cell. Because of a possible compensatory increase in mtDNA copies per cell to maintain mitochondrial function in the setting of mitochondrial dysfunction, overall OXPHOS activity was not different between the groups. The long-term sustainability of this compensatory response in these survivors at risk for cardiac dysfunction over their lifespan is concerning.

Increasing role of the cancer chemotherapeutic doxorubicin in cellular metabolism

OBJECTIVES

The use of doxorubicin, a drug utilised for many years to treat a wide variety of cancers, has long been limited due to the significant toxicity that can occur not only during, but also years after treatment. It has multiple mechanisms of action including the intercalation of DNA, inhibition of topoisomerase II and the production of free radicals. We review the literature, with the aim of highlighting the role of drug concentration being an important determinant on the unfolding cell biological events that lead to cell stasis or death.

METHODS

The PubMed database was consulted to compile this review.

KEY FINDINGS

It has been found that the various mechanisms of action at the disposal of doxorubicin culminate in either cell death or cell growth arrest through various cell biological events, such as apoptosis, autophagy, senescence and necrosis. Which of these events is the eventual cause of cell death or growth arrest appears to vary depending on factors such as the patient, cell and cancer type, doxorubicin concentration and the duration of treatment.

CONCLUSIONS

Further understanding of doxorubicin's influence on cell biological events could lead to an improvement in the drug's efficacy and reduce toxicity.

Early transcriptional changes in cardiac mitochondria during chronic doxorubicin exposure and mitigation by dexrazoxane in mice

Identification of early biomarkers of cardiotoxicity could help initiate means to ameliorate the cardiotoxic actions of clinically useful drugs such as doxorubicin (DOX). Since DOX has been shown to target mitochondria, transcriptional levels of mitochondria-related genes were evaluated to identify early candidate biomarkers in hearts of male B6C3F1 mice given a weekly intravenous dose of 3mg/kg DOX or saline (SAL) for 2, 3, 4, 6, or 8 weeks (6, 9, 12, 18, or 24 mg/kg cumulative DOX doses, respectively). Also, a group of mice was pretreated (intraperitoneally) with the cardio-protectant, dexrazoxane (DXZ; 60 mg/kg) 30 min before each weekly dose of DOX or SAL. At necropsy a week after the last dose, increased plasma concentrations of cardiac troponin T (cTnT) were detected at 18 and 24 mg/kg cumulative DOX doses, whereas myocardial alterations were observed only at the 24 mg/kg dose. Of 1019 genes interrogated, 185, 109, 140, 184, and 451 genes were differentially expressed at 6, 9, 12, 18, and 24 mg/kg cumulative DOX doses, respectively, compared to concurrent SAL-treated controls. Of these, expression of 61 genes associated with energy metabolism and apoptosis was significantly altered before and after occurrence of myocardial injury, suggesting these as early genomics markers of cardiotoxicity. Much of these DOX-induced transcriptional changes were attenuated by pretreatment of mice with DXZ. Also, DXZ treatment significantly reduced plasma cTnT concentration and completely ameliorated cardiac alterations induced by 24 mg/kg cumulative DOX. This information on early transcriptional changes during DOX treatment may be useful in designing cardioprotective strategies targeting mitochondria.

Effect of Remote Ischaemic Conditioning in Oncology Patients Undergoing Chemotherapy: Rationale and Design of the ERIC-ONC Study--A Single-Center, Blinded, Randomized Controlled Trial

Cancer survival continues to improve, and thus cardiovascular consequences of chemotherapy are increasingly important determinants of long‐term morbidity and mortality. Conventional strategies to protect the heart from chemotherapy have important hemodynamic or myelosuppressive side effects. Remote ischemic conditioning (RIC) using intermittent limb ischemia‐reperfusion reduces myocardial injury in the setting of percutaneous coronary intervention. Anthracycline cardiotoxicity and ischemia‐reperfusion injury share common biochemical pathways in cardiomyocytes. The potential for RIC as a novel treatment to reduce subclinical myocyte injury in chemotherapy has never been explored and will be investigated in the Effect of Remote Ischaemic Conditioning in Oncology (ERIC‐ONC) trial (clinicaltrials.gov NCT 02471885). The ERIC‐ONC trial is a single‐center, blinded, randomized, sham‐controlled study. We aim to recruit 128 adult oncology patients undergoing anthracycline‐based chemotherapy treatment, randomized in a 1:1 ratio into 2 groups: (1) sham procedure or (2) RIC, comprising 4, 5‐minute cycles of upper arm blood pressure cuff inflations and deflations, immediately before each cycle of chemotherapy. The primary outcome measure, defining cardiac injury, will be high‐sensitivity troponin‐T over 6 cycles of chemotherapy and 12 months follow‐up. Secondary outcome measures will include clinical, electrical, structural, and biochemical endpoints comprising major adverse cardiovascular clinical events, incidence of cardiac arrhythmia over 14 days at cycle 5/6, echocardiographic ventricular function, N‐terminal pro‐brain natriuretic peptide levels at 3 months follow‐up, and changes in mitochondrial DNA, micro‐RNA, and proteomics after chemotherapy. The ERIC‐ONC trial will determine the efficacy of RIC as a novel, noninvasive, nonpharmacological, low‐cost cardioprotectant in cancer patients undergoing anthracycline‐based chemotherapy.

Reduced Glucose Sensation Can Increase the Fitness of Saccharomyces cerevisiae Lacking Mitochondrial DNA

Damage to the mitochondrial genome (mtDNA) can lead to diseases for which there are no clearly effective treatments. Since mitochondrial function and biogenesis are controlled by the nutrient environment of the cell, it is possible that perturbation of conserved, nutrient-sensing pathways may successfully treat mitochondrial disease. We found that restricting glucose or otherwise reducing the activity of the protein kinase A (PKA) pathway can lead to improved proliferation of Saccharomyces cerevisiae cells lacking mtDNA and that the transcriptional response to mtDNA loss is reduced in cells with diminished PKA activity. We have excluded many pathways and proteins from being individually responsible for the benefits provided to cells lacking mtDNA by PKA inhibition, and we found that robust import of mitochondrial polytopic membrane proteins may be required in order for cells without mtDNA to receive the full benefits of PKA reduction. Finally, we have discovered that the transcription of genes involved in arginine biosynthesis and aromatic amino acid catabolism is altered after mtDNA damage. Our results highlight the potential importance of nutrient detection and availability on the outcome of mitochondrial dysfunction.

The differential effects of green tea on dose-dependent doxorubicin toxicity

Background

Doxorubicin (DOX) is an anticancer drug displaying cardiac and hepatic adverse effects mostly dependent on oxidative stress. Green tea (GT) has been reported to play a protective role in diseases resulting from oxidative stress.

Objective

The objective of this study was to evaluate if GT protects against DOX-induced oxidative stress, heart and liver morphological changes, and metabolic disorders.

Methods

Male Wistar rats received intraperitoneal injection of DOX (1.0 or 2.0 mg/kg b.w.) for 7 weeks or concomitantly GT extract soluble in drinking water.

Results

There were multidirectional effects of GT on blood metabolic parameters changed by DOX. Among all tested biochemical parameters, statistically significant protection of GT against DOX-induced changes was revealed in case of blood fatty acid–binding protein, brain natriuretic peptide, and superoxide dismutase.

Conclusion

DOX caused oxidative stress in both organs. It was inhibited by GT in the heart but remained unchanged in the liver. DOX-induced general toxicity and histopathological changes in the heart and in the liver were mitigated by GT at a higher dose of DOX and augmented in rats treated with a lower dose of the drug.

Taurine zinc solid dispersions attenuate doxorubicin-induced hepatotoxicity and cardiotoxicity in rats

The clinical efficacy of anthracycline anti-neoplastic agents is limited by cardiac and hepatic toxicities. The aim of this study was to assess the hepatoprotective and cardioprotective effects of taurine zinc solid dispersions, which is a newly-synthesized taurine zinc compound, against doxorubicin-induced toxicity in Sprague-Dawley rats intraperitoneally injected with doxorubicin hydrochloride (3mg/kg) three times a week (seven injections) over 28 days. Hemodynamic parameters, levels of liver toxicity markers and oxidative stress were assessed. Taurine zinc significantly attenuated the reductions in blood pressure, left ventricular pressure and ± dp/dtmax, increases in serum alanine aminotransferase and aspartate aminotransferase activities, and reductions in serum Zn(2+) and albumin levels (P<0.05 or 0.01) induced by doxorubicin. In rats treated with doxorubicin, taurine zinc dose-dependently increased liver superoxide dismutase activity and glutathione concentration, and decreased malondialdehyde level (P<0.01). qBase(+) was used to evaluate the stability of eight candidate reference genes for real-time quantitative reverse-transcription PCR. Taurine zinc dose-dependently increased liver heme oxygenase-1 and UDP-glucuronyl transferase mRNA and protein expression (P<0.01). Western blotting demonstrated that taurine zinc inhibited c-Jun N-terminal kinase phosphorylation by upregulating dual-specificity phosphoprotein phosphatase-1. Additionally, taurine zinc inhibited cardiomyocyte apoptosis as there was decreased TUNEL/DAPI positivity and protein expression of caspase-3. These results indicate that taurine zinc solid dispersions prevent the side-effects of anthracycline-based anticancer therapy. The mechanisms might be associated with the enhancement of antioxidant defense system partly through activating transcription to synthesize endogenous phase II medicine enzymes and anti-apoptosis through inhibiting JNK phosphorylation.

Accumulation of Mitochondrial DNA Mutations Disrupts Cardiac Progenitor Cell Function and Reduces Survival

Transfer of cardiac progenitor cells (CPCs) improves cardiac function in heart failure patients. However, CPC function is reduced with age, limiting their regenerative potential. Aging is associated with numerous changes in cells including accumulation of mitochondrial DNA (mtDNA) mutations, but it is unknown how this impacts CPC function. Here, we demonstrate that acquisition of mtDNA mutations disrupts mitochondrial function, enhances mitophagy, and reduces the replicative and regenerative capacities of the CPCs. We show that activation of differentiation in CPCs is associated with expansion of the mitochondrial network and increased mitochondrial oxidative phosphorylation. Interestingly, mutant CPCs are deficient in mitochondrial respiration and rely on glycolysis for energy. In response to differentiation, these cells fail to activate mitochondrial respiration. This inability to meet the increased energy demand leads to activation of cell death. These findings demonstrate the consequences of accumulating mtDNA mutations and the importance of mtDNA integrity in CPC homeostasis and regenerative potential.

Anthracycline treatment and ventricular remodeling in left ventricular assist device patients

Nonischemic cardiomyopathy can complicate antineoplastic therapy and lead to irreversible heart failure. We evaluated structural changes at the time of left ventricular assist device implantation in heart failure patients who had been exposed to anthracycline, and we correlated those changes with clinical presentation. We retrospectively studied left ventricular core samples taken at implantation of the HeartMate II left ventricular assist device in 12 heart failure patients (mean age, 46 ± 16 yr) who had histories of anthracycline exposure. We evaluated those samples for hypertrophy, myocytolysis, and fibrosis. Histopathologic findings showed moderate-to-severe myocyte hypertrophy, moderate myocytolysis, and perivascular and interstitial fibrosis with areas of replacement fibrosis. Ultrastructural studies revealed marked decreases in myofibrils, diffuse mitochondrial swelling, and disorganization of the sarcoplasmic reticulum. The interval between anthracycline therapy and heart failure was a mean of 6.8 ± 5.7 years; duration of heart failure symptoms, 38 ± 47 months; and duration of device support, 414 ± 266 days. Four patients are continuing on device support, 3 have undergone transplantation, 3 have undergone device explantation, and 2 have died. The time of heart failure onset and the duration of symptoms did not correlate with the severity and extent of the histopathologic changes. The histopathologic findings and the clinical course varied in heart failure patients with anthracycline exposure. No correlation was observed between anthracycline therapy and the development or duration of heart failure symptoms, severity of histopathologic changes, or outcomes.

Current Views on Anthracycline Cardiotoxicity in Childhood Cancer Survivors

Owing to their high efficacy, anthracycline antibiotics are included in numerous chemotherapeutic regimens used-often in combination with radiation therapy and/or surgery-in treatment of solid tumours and blood malignancies, both in children and adults. However, the efficacy of modern cancer treatments, owing to which the population of cancer survivors has been on the rise in recent years, may be limited by the risk of serious complications involving multiple organs and systems, including the cardiovascular system. Being an important side effect of anthracyclines, cardiotoxicity may limit the efficacy of cancer therapies in the acute phase (i.e. during the treatment) and induce the long-term sequelae, observed years after treatment completion in childhood cancer survivors. It is very important to understand the cardiotoxicity-associated mechanisms and to determine its risk factors in order to develop and/or improve the effective countermeasures. Based on published data, the paper provides an outline of current views on anthracycline cardiotoxicity and discusses such aspects as molecular mechanisms of cardiotoxicity and its clinical manifestations as well as the new preventive strategies and diagnostic techniques used for the assessment of cardiovascular abnormalities. The widespread awareness of cancer treatment-related cardiotoxicity among the healthcare professionals may significantly improve the quality of life of the childhood cancer survivors.

Ophiopogonin D attenuates doxorubicin-induced autophagic cell death by relieving mitochondrial damage in vitro and in vivo

It has been reported that ophiopogonin D (OP-D), a steroidal glycoside and an active component extracted from Ophiopogon japonicas, promotes antioxidative protection of the cardiovascular system. However, it is unknown whether OP-D exerts protective effects against doxorubicin (DOX)-induced autophagic cardiomyocyte injury. Here, we demonstrate that DOX induced excessive autophagy through the generation of reactive oxygen species (ROS) in H9c2 cells and in mouse hearts, which was indicated by a significant increase in the number of autophagic vacuoles, LC3-II/LC3-I ratio, and upregulation of the expression of GFP-LC3. Pretreatment with OP-D partially attenuated the above phenomena, similar to the effects of treatment with 3-methyladenine. In addition, OP-D treatment significantly relieved the disruption of the mitochondrial membrane potential by antioxidative effects through downregulating the expression of both phosphorylated c-Jun N-terminal kinase and extracellular signal-regulated kinase. The ability of OP-D to reduce the generation of ROS due to mitochondrial damage and, consequently, to inhibit autophagic activity partially accounts for its protective effects in the hearts against DOX-induced toxicity.

Quercetin attenuates doxorubicin cardiotoxicity by modulating Bmi-1 expression

BACKGROUND AND PURPOSE

Doxorubicin-based chemotherapy induces cardiotoxicity, which limits its clinical application. We previously reported the protective effects of quercetin against doxorubicin-induced hepatotoxicity. In this study, we tested the effects of quercetin on the expression of Bmi-1, a protein regulating mitochondrial function and ROS generation, as a mechanism underlying quercetin-mediated protection against doxorubicin-induced cardiotoxicity.

EXPERIMENTAL APPROACH

Effects of quercetin on doxorubicin-induced cardiotoxicity was evaluated using H9c2 cardiomyocytes and C57BL/6 mice. Changes in apoptosis, mitochondrial function, oxidative stress and related signalling were evaluated in H9c2 cells. Cardiac function, serum enzyme activity and reactive oxygen species (ROS) generation were measured in mice after a single injection of doxorubicin with or without quercetin pre-treatment.

KEY RESULTS

In H9c2 cells, quercetin reduced doxorubicin-induced apoptosis, mitochondrial dysfunction, ROS generation and DNA double-strand breaks. The quercetin-mediated protection against doxorubicin toxicity was characterized by decreased expression of Bid, p53 and oxidase (p47 and Nox1) and by increased expression of Bcl-2 and Bmi-1. Bmi-1 siRNA abolished the protective effect of quercetin against doxorubicin-induced toxicity in H9c2 cells. Furthermore, quercetin protected mice from doxorubicin-induced cardiac dysfunction that was accompanied by reduced ROS levels and lipid peroxidation, but enhanced the expression of Bmi-1 and anti-oxidative superoxide dismutase.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that quercetin decreased doxorubicin-induced cardiotoxicity in vitro and in vivo by reducing oxidative stress by up-regulation of Bmi-1 expression. The findings presented in this study have potential applications in preventing doxorubicin-induced cardiomyopathy.

An update on cardio-oncology

Over the past decades, there have been great advancements in the survival outcome of patients with cancer. As a consequence, treatment regimens are being extended to patient populations that would not have qualified in the past based on comorbidities and age. Furthermore, the anti-cancer regimens, which have been and are being used, can cause considerable morbidity and even mortality. In fact, new drugs such as tyrosine kinase inhibitors have yielded unanticipated side effects in frequency and severity. The cardiovascular disease spectrum is an important element in all of these. In order to optimize the outcome of cancer patients with cardiovascular diseases existing prior to cancer treatment or developing as a consequence of it, a new discipline called "cardio-oncology" has evolved over the past few years. Herein, we review the latest developments in this field including cardiotoxicities, vascular toxicities, and arrhythmias. This field is taking on more shape as cardiologists, oncologists, and hematologists are forming alliances, programs, and clinics, supported by the development of expert consensus statements on best management approaches and care of the cancer patient with cardiovascular diseases.

Evaluation and management of patients with heart disease and cancer: cardio-oncology

The care for patients with cancer has advanced greatly over the past decades. A combination of earlier cancer diagnosis and greater use of traditional and new systemic treatments has decreased cancer-related mortality. Effective cancer therapies, however, can result in short- and long-term comorbidities that can decrease the net clinical gain by affecting quality of life and survival. In particular, cardiovascular complications of cancer treatments can have a profound effect on the health of patients with cancer and are more common among those with recognized or unrecognized underlying cardiovascular diseases. A new discipline termed cardio-oncology has thus evolved to address the cardiovascular needs of patients with cancer and optimize their care in a multidisciplinary approach. This review provides a brief introduction and background on this emerging field and then focuses on its practical aspects including cardiovascular risk assessment and prevention before cancer treatment, cardiovascular surveillance and therapy during cancer treatment, and cardiovascular monitoring and management after cancer therapy. The content of this review is based on a literature search of PubMed between January 1, 1960, and February 1, 2014, using the search terms cancer, cardiomyopathy, cardiotoxicity, cardio-oncology, chemotherapy, heart failure, and radiation.

Mitochondrial topoisomerase I (top1mt) is a novel limiting factor of doxorubicin cardiotoxicity

PURPOSE

Doxorubicin is one of the most effective chemotherapeutic agents. However, up to 30% of the patients treated with doxorubicin suffer from congestive heart failure. The mechanism of doxorubicin cardiotoxicity is likely multifactorial and most importantly, the genetic factors predisposing to doxorubicin cardiotoxicity are unknown. On the basis of the fact that mtDNA lesions and mitochondrial dysfunctions have been found in human hearts exposed to doxorubicin and that mitochondrial topoisomerase 1 (Top1mt) specifically controls mtDNA homeostasis, we hypothesized that Top1mt knockout (KO) mice might exhibit hypersensitivity to doxorubicin.

EXPERIMENTAL DESIGN

Wild-type (WT) and KO Top1mt mice were treated once a week with 4 mg/kg doxorubicin for 8 weeks. Heart tissues were analyzed one week after the last treatment.

RESULTS

Genetic inactivation of Top1mt in mice accentuates mtDNA copy number loss and mtDNA damage in heart tissue following doxorubicin treatment. Top1mt KO mice also fail to maintain respiratory chain protein production and mitochondrial cristae ultrastructure organization. These mitochondrial defects result in decreased O2 consumption, increased reactive oxygen species production, and enhanced heart muscle damage in animals treated with doxorubicin. Accordingly, Top1mt KO mice die within 45 days after the last doxorubicin injection, whereas the WT mice survive.

CONCLUSIONS

Our results provide evidence that Top1mt, which is conserved across vertebrates, is critical for cardiac tolerance to doxorubicin and adaptive response to doxorubicin cardiotoxicity. They also suggest the potential of Top1mt single-nucleotide polymorphisms testing to investigate patient susceptibility to doxorubicin-induced cardiotoxicity.