Prospective randomized study of the role of N-acetyl cysteine in reversing doxorubicin-induced cardiomyopathy

Interplay of Reactive Oxygen Species (ROS) and Epigenetic Remodelling in Cardiovascular Diseases Pathogenesis: A Contemporary Perspective

Cardiovascular diseases (CVDs) continue to be the leading cause of mortality worldwide, necessitating the development of novel therapies. Despite therapeutic advancements, the underlying mechanisms remain elusive. Reactive oxygen species (ROS) show detrimental effects at high concentrations but act as essential signalling molecules at physiological levels, playing a critical role in the pathophysiology of CVD. However, the link between pathologically elevated ROS and CVDs pathogenesis remains poorly understood. Recent research has highlighted the remodelling of the epigenetic landscape as a crucial factor in CVD pathologies. Epigenetic changes encompass alterations in DNA methylation, post-translational histone modifications, adenosine triphosphate (ATP)-dependent chromatin modifications, and noncoding RNA transcripts. Unravelling the intricate link between ROS and epigenetic changes in CVD is challenging due to the complexity of epigenetic signals in gene regulation. This review aims to provide insights into the role of ROS in modulating the epigenetic landscape within the cardiovascular system. Understanding these interactions may offer novel therapeutic strategies for managing CVD by targeting ROS-induced epigenetic changes. It has been widely accepted that epigenetic modifications are established during development and remain fixed once the lineage-specific gene expression pattern is achieved. However, emerging evidence has unveiled its remarkable dynamism. Consequently, it is now increasingly recognized that epigenetic modifications may serve as a crucial link between ROS and the underlying mechanisms implicated in CVD.

PCSK9 Inhibitors and Anthracyclines: The Future of Cardioprotection in Cardio-Oncology

The field of cardio-oncology is an expanding frontier within cardiovascular medicine, and the need for evidence-based guidelines is apparent. One of the emerging focuses within cardio-oncology is the concomitant use of medications for cardioprotection in the setting of chemotherapy regimens that have known cardiovascular toxicity. While clinical trials focusing on cardioprotection during chemotherapy are sparse, an inaugural trial exploring the prophylactic potential of Sodium-Glucose Cotransporter-2 inhibitors (SGLT2is) for anthracycline (ANT)-induced cardiotoxicity has recently commenced. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, though less studied in this oncology demographic, have exhibited promise in preclinical studies for conferring cardiac protection during non-ischemic toxic insults. While primarily used to reduce low-density lipoprotein, PCSK9 inhibitors exhibit pleiotropic effects, including the attenuation of inflammation, reactive oxygen species, and endothelial dysfunction. In ANT-induced cardiotoxicity, these same processes are accelerated, resulting in premature termination of treatment, chronic cardiovascular sequelae, heart failure, and/or death. This review serves a dual purpose: firstly, to provide a concise overview of the mechanisms implicated in ANT-induced cardiotoxicity, and, finally, to summarize the existing preclinical data supporting the theoretical possibility of the cardioprotective effects of PCSK9 inhibition in ANT-induced cardiotoxicity.

Comparative In Vitro Study of the Cytotoxic Effects of Doxorubicin's Main Metabolites on Cardiac AC16 Cells Versus the Parent Drug

Doxorubicin (DOX; also known as adriamycin) serves as a crucial antineoplastic agent in cancer treatment; however, its clinical utility is hampered by its' intrinsic cardiotoxicity. Although most DOX biotransformation occurs in the liver, a comprehensive understanding of the impact of DOX biotransformation and its' metabolites on its induced cardiotoxicity remains to be fully elucidated. This study aimed to explore the role of biotransformation and DOX's main metabolites in its induced cardiotoxicity in human differentiated cardiac AC16 cells. A key discovery from our study is that modulating metabolism had minimal effects on DOX-induced cytotoxicity: even so, metyrapone (a non-specific inhibitor of cytochrome P450) increased DOX-induced cytotoxicity at 2 µM, while diallyl sulphide (a CYP2E1 inhibitor) decreased the 1 µM DOX-triggered cytotoxicity. Then, the toxicity of the main DOX metabolites, doxorubicinol [(DOXol, 0.5 to 10 µM), doxorubicinone (DOXone, 1 to 10 µM), and 7-deoxydoxorubicinone (7-DeoxyDOX, 1 to 10 µM)] was compared to DOX (0.5 to 10 µM) following a 48-h exposure. All metabolites evaluated, DOXol, DOXone, and 7-DeoxyDOX caused mitochondrial dysfunction in differentiated AC16 cells, but only at 2 µM. In contrast, DOX elicited comparable cytotoxicity, but at half the concentration. Similarly, all metabolites, except 7-DeoxyDOX impacted on lysosomal ability to uptake neutral red. Therefore, the present study showed that the modulation of DOX metabolism demonstrated minimal impact on its cytotoxicity, with the main metabolites exhibiting lower toxicity to AC16 cardiac cells compared to DOX. In conclusion, our findings suggest that metabolism may not be a pivotal factor in mediating DOX's cardiotoxic effects.

A review of the pathophysiological mechanisms of doxorubicin-induced cardiotoxicity and aging

The population of cancer survivors is rapidly increasing due to improving healthcare. However, cancer therapies often have long-term side effects. One example is cancer therapy-related cardiac dysfunction (CTRCD) caused by doxorubicin: up to 9% of the cancer patients treated with this drug develop heart failure at a later stage. In recent years, doxorubicin-induced cardiotoxicity has been associated with an accelerated aging phenotype and cellular senescence in the heart. In this review we explain the evidence of an accelerated aging phenotype in the doxorubicin-treated heart by comparing it to healthy aged hearts, and shed light on treatment strategies that are proposed in pre-clinical settings. We will discuss the accelerated aging phenotype and the impact it could have in the clinic and future research.

N-Acetylcysteine and Atherosclerosis: Promises and Challenges

Atherosclerosis remains a leading cause of cardiovascular diseases. Although the mechanism for atherosclerosis is complex and has not been fully understood, inflammation and oxidative stress play a critical role in the development and progression of atherosclerosis. N-acetylcysteine (NAC) has been used as a mucolytic agent and an antidote for acetaminophen overdose with a well-established safety profile. NAC has antioxidant and anti-inflammatory effects through multiple mechanisms, including an increase in the intracellular glutathione level and an attenuation of the nuclear factor kappa-B mediated production of inflammatory cytokines like tumor necrosis factor-alpha and interleukins. Numerous animal studies have demonstrated that NAC significantly decreases the development and progression of atherosclerosis. However, the data on the outcomes of clinical studies in patients with atherosclerosis have been limited and inconsistent. The purpose of this review is to summarize the data on the effect of NAC on atherosclerosis from both pre-clinical and clinical studies and discuss the potential mechanisms of action of NAC on atherosclerosis, as well as challenges in the field.

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

Mitochondrial-Targeted Therapy for Doxorubicin-Induced Cardiotoxicity

Anthracyclines, such as doxorubicin, are effective chemotherapeutic agents for the treatment of cancer, but their clinical use is associated with severe and potentially life-threatening cardiotoxicity. Despite decades of research, treatment options remain limited. The mitochondria is commonly considered to be the main target of doxorubicin and mitochondrial dysfunction is the hallmark of doxorubicin-induced cardiotoxicity. Here, we review the pathogenic mechanisms of doxorubicin-induced cardiotoxicity and present an update on cardioprotective strategies for this disorder. Specifically, we focus on strategies that can protect the mitochondria and cover different therapeutic modalities encompassing small molecules, post-transcriptional regulators, and mitochondrial transfer. We also discuss the shortcomings of existing models of doxorubicin-induced cardiotoxicity and explore advances in the use of human pluripotent stem cell derived cardiomyocytes as a platform to facilitate the identification of novel treatments against this disorder.

Protective Effect of Qiliqiangxin against Doxorubicin-Induced Cardiomyopathy by Suppressing Excessive Autophagy and Apoptosis

Background

Doxorubicin (DOX) is one of the most potent and widely prescribed antitumor agents; however, its clinical use is limited by cardiac side effects. In this study, we aimed to clarify the protective effects of Qiliqiangxin (QL), a traditional Chinese medicine formulation, on DOX-induced cardiotoxicity and to explore the underlying mechanisms in a rat model.

Methods

Male Sprague-Dawley rats were randomly assigned to three groups with different interventions (control, DOX, and DOX plus QL) for 31 days. Cardiac function was monitored. The levels of oxidative stress in plasm were detected, the activities of autophagy and apoptosis in rat hearts were determined, and then, the related PI3K/AKT/mTOR signal pathway regulating apoptosis and autophagy was investigated.

Results

QL improved cardiac dysfunction and decreased the increased level of cardiac enzymes in plasm caused by DOX. Moreover, DOX exposure resulted in oxidative stress enhancement, which was suppressed by QL treatment. Then, we discovered that DOX intervention caused the apoptosis of cardiomyocytes by activating the mitochondrial-dependent apoptotic pathway which was strongly inhibited by QL treatment. Furthermore, there was a significant increase in autophagic activities in the DOX-stimulated myocardium. Administration of QL substantially inhibited the enhanced autophagic activities, which might be attributed to the activation of PI3K/AKT/mTOR cascade, followed by suppression of ULK1 activity.

Conclusions

QL exhibited protective roles against DOX-induced cardiotoxicity possibly via mediating the PI3K/AKT/mTOR pathway, leading to inhibition of autophagy and subsequent apoptosis activities.

Oxidative stress-responsive apoptosis inducing protein (ORAIP) plays a critical role in doxorubicin-induced apoptosis in rat cardiac myocytes

BACKGROUND

Oxidative stress is implicated in the pathogenesis of doxorubicin-induced apoptosis in cardiac myocytes. However, the precise mechanism remains uncertain. We identified an apoptosis-inducing humoral factor, in a conditioned medium from cardiac myocytes subjected to hypoxia/reoxygenation, to be 69th tyrosine-sulfated eukaryotic translation initiation factor 5A (eIF5A). We named this novel secreted form of eIF5A, Oxidative stress-Responsive Apoptosis Inducing Protein (ORAIP). We confirmed that ischemia/reperfusion, ultraviolet-irradiation, and ionizing radiation significantly increased plasma levels of ORAIP in vivo, supporting that secretion of ORAIP is specific to the oxidative stress. To investigate the role of ORAIP in doxorubicin-induced apoptosis of cardiac myocytes.

METHODS

We analyzed plasma levels of ORAIP in rats treated with doxorubicin (10 mg/Kg) in vivo, and the effects of neutralizing anti-ORAIP monoclonal antibody (mAb) on doxorubicin-induced apoptosis of cardiac myocytes in vitro.

RESULTS

The (mean ± SE) plasma ORAIP levels before doxorubicin administration were (13.7 ± 2.7) ng/mL, they markedly increased with peak levels ([178.6 ± 6.5] ng/mL, p < 0.00001, vs. before administration) at 20 to 60 min after doxorubicin administration, then gradually decreased to (118.0 ± 4.8) ng/mL at 120 min. Treatment with a neutralizing anti-ORAIP mAb significantly (nearly 50%) suppressed doxorubicin-induced apoptosis of cardiac myocytes.

CONCLUSIONS

These data indicate that doxorubicin induces oxidative stress resulting in the strong expression of ORAIP in cardiac myocytes and marked secretion of ORAIP into peripheral circulation. This strongly suggests that ORAIP can be a novel sensitive biomarker as well as a possible therapeutic target for doxorubicin-induced cell injury in anti-cancer therapy.

Oral N-acetylcysteine as an adjunct to standard medical therapy improved heart function in cases with stable class II and III systolic heart failure

BACKGROUND

This research attempted to assess whether N-acetylcysteine (NAC) as adjunctive therapy can be useful in the treatment of patients with heart failure (HF).

METHODS

Fifty-five cases with diagnosed systolic HF and stable symptomatic New York Heart Association (NYHA) functional class II and III and on optimal medical treatment of HF for at least 3 months were assigned for receiving oral NAC (600 mg twice daily) or placebo for 12 weeks. The outcomes were changes in the echocardiographic hemodynamic indices as well as the patients' functional capacity assessed by NYHA classification over a 12-week treatment.

RESULTS

Compared to placebo, NAC more significantly improved the systolic left ventricular (LV) function expressed as the ejection fraction and Tei index. These changes are accompanied by more improvement in other LV echocardiographic indices including LV end-diastolic volume index and LV global longitudinal strain in the patients receiving NAC in comparison with those receiving placebo. In parallel with the improvement of LV function, right ventricular (RV) function expressed as RV fractional area change and RV Tei-index also got more improvement in those receiving NAC than those receiving placebo. However, the change in RV global longitudinal strain did not show a significant difference between study groups. Additionally, at week 12, the distribution of the NYHA functional class also shifted toward a better outcome in the NAC group in comparison with the placebo group; however, it was not significant.

CONCLUSIONS

These preliminary data support experimental findings showing that NAC supplementation is able to improve heart function.

TRIAL REGISTRATION

The registration of the trial was done at the Iranian Registry of Clinical Trials ( www.irct.ir ). Identifier code: IRCT20120215009014N333. Registration date: 2020-01-11.

CYP1B1 as a therapeutic target in cardio-oncology

Cardiovascular complications have been frequently reported in cancer patients and survivors, mainly because of various cardiotoxic cancer treatments. Despite the known cardiovascular toxic effects of these treatments, they are still clinically used because of their effectiveness as anti-cancer agents. In this review, we discuss the growing body of evidence suggesting that inhibition of the cytochrome P450 1B1 enzyme (CYP1B1) can be a promising therapeutic strategy that has the potential to prevent cancer treatment-induced cardiovascular complications without reducing their anti-cancer effects. CYP1B1 is an extrahepatic enzyme that is expressed in cardiovascular tissues and overexpressed in different types of cancers. A growing body of evidence is demonstrating a detrimental role of CYP1B1 in both cardiovascular diseases and cancer, via perturbed metabolism of endogenous compounds, production of carcinogenic metabolites, DNA adduct formation, and generation of reactive oxygen species (ROS). Several chemotherapeutic agents have been shown to induce CYP1B1 in cardiovascular and cancer cells, possibly via activating the Aryl hydrocarbon Receptor (AhR), ROS generation, and inflammatory cytokines. Induction of CYP1B1 is detrimental in many ways. First, it can induce or exacerbate cancer treatment-induced cardiovascular complications. Second, it may lead to significant chemo/radio-resistance, undermining both the safety and effectiveness of cancer treatments. Therefore, numerous preclinical studies demonstrate that inhibition of CYP1B1 protects against chemotherapy-induced cardiotoxicity and prevents chemo- and radio-resistance. Most of these studies have utilized phytochemicals to inhibit CYP1B1. Since phytochemicals have multiple targets, future studies are needed to discern the specific contribution of CYP1B1 to the cardioprotective and chemo/radio-sensitizing effects of these phytochemicals.

Cardiotoxic Effect of Modern Anthracycline Dosing on Left Ventricular Ejection Fraction: A Systematic Review and Meta-Analysis of Placebo Arms From Randomized Controlled Trials

Background

Anthracyclines are a key chemotherapeutic agent used against hematological and solid organ malignancies. However, their benefits in cancer survival are limited by cumulative, dose‐related cardiotoxicity. The impact of anthracyclines on left ventricular ejection fraction (LVEF), in the era of modern chemotherapy regimens, remains unclear.

Methods and Results

Three databases (CENTRAL, MEDLINE, and SCOPUS) were systematically searched for randomized trials evaluating cardioprotective agents against placebo, in preventing cardiotoxicity. Echocardiography or magnetic resonance measured LVEF pre‐ and post‐anthracycline‐based chemotherapy was abstracted from placebo trial arms. The key terms included “anthracycline,” “cardiotoxicity” and “randomized.” A doxorubicin equivalent anthracycline dose metric was calculated to compare different anthracyclines. A random‐effects model was used to pool mean difference in LVEF after anthracycline. Meta‐regressions were calculated to identify variation sources. We included 660 patients from 19 trials. The weighted mean baseline LVEF across studies was 62.6%, and follow‐up LVEF assessment was performed at 6 months. The pooled mean decline in LVEF among placebo arms was 5.4% (95% CI, 3.5%–7.3%) with a doxorubicin equivalent anthracycline dose of 385 mg/m². Meta‐regression analysis showed no significant difference in LVEF against doxorubicin equivalent anthracycline dose as continuous (P=0.29) or against published cut‐offs for cardiotoxicity (250 mg/m², P=0.21; 360 mg/m², P=0.40; and 400 mg/m², P=0.66). The differences in mean LVEF were not associated with sex, adjunct chemotherapy, or cancer type.

Conclusions

The magnitude of LVEF impairment post‐anthracycline therapy appears less than previously described with modern dosing regimens. This may improve the accuracy of power calculation for future clinical trials assessing the role of cardioprotective therapy.

New insights into the activities and toxicities of the old anticancer drug doxorubicin

The anthracycline drug doxorubicin is among the most used—and useful—chemotherapeutics. While doxorubicin is highly effective in the treatment of various hematopoietic malignancies and solid tumours, its application is limited by severe adverse effects, including irreversible cardiotoxicity, therapy‐related malignancies and gonadotoxicity. This continues to motivate investigation into the mechanisms of anthracycline activities and toxicities, with the aim to overcome the latter without sacrificing the former. It has long been appreciated that doxorubicin causes DNA double‐strand breaks due to poisoning topoisomerase II. More recently, it became clear that doxorubicin also leads to chromatin damage achieved through eviction of histones from select sites in the genome. Evaluation of these activities in various anthracycline analogues has revealed that chromatin damage makes a major contribution to the efficacy of anthracycline drugs. Furthermore, the DNA‐damaging effect conspires with chromatin damage to cause a number of adverse effects. Structure–activity relationships within the anthracycline family offer opportunities for chemical separation of these activities towards development of effective analogues with limited adverse effects. In this review, we elaborate on our current understanding of the different activities of doxorubicin and their contributions to drug efficacy and side effects. We then offer our perspective on how the activities of this old anticancer drug can be amended in new ways to benefit cancer patients, by providing effective treatment with improved quality of life.

Heart Failure in Relation to Anthracyclines and Other Chemotherapies

Anthracyclines are the cornerstone of therapy for a wide range of solid and hematologic malignancies; however, their use is limited by the risk of chemotherapy-induced cardiotoxicity leading to cardiomyopathy and heart failure. The incidence of cardiotoxicity in the literature depends on the definition being used, anthracycline dose, duration of follow-up, and surveillance methods used to identify cardiac injury. The reported risk of clinical heart failure has been around 2% to 4% with low-dose anthracycline regimens, whereas the incidence of cardiac injury defined by an abnormal increase in cardiac biomarkers has been reported as high as 35%. Multiple mechanisms have been proposed for anthracycline cardiotoxicity, including the deleterious effects of oxidative stress and reactive oxygen species and the inhibition of topoisomerase II beta, which leads to cardiomyocyte death. In addition, genetic susceptibility is an emerging field that is currently generating active research. The risk factors associated with anthracycline cardiotoxicity include lifetime cumulative dose, age, prior cardiac dysfunction, and the presence of cardiovascular risk factors, in particular hypertension. In this review, we summarize the incidence, mechanisms, and risk factors for anthracycline-mediated left ventricular dysfunction and discuss the role of risk stratification and early detection in patient management.

Effects of doxorubicin-induced cardiotoxicity on cardiac mitochondrial dynamics and mitochondrial function: Insights for future interventions

Anthracyclines is an effective chemotherapeutic treatment used for many types of cancer. However, high cumulative dosage of anthracyclines leads to cardiac toxicity and heart failure. Dysregulation of mitochondrial dynamics and function are major pathways driving this toxicity. Several pharmacological and non‐pharmacological interventions aiming to attenuate cardiac toxicity by targeting mitochondrial dynamics and function have shown beneficial effects in cell and animal models. However, in clinical practice, there is currently no standard therapy for the prevention of anthracycline‐induced cardiotoxicity. This review summarizes current reports on the impact of anthracyclines on cardiac mitochondrial dynamics and mitochondrial function and potential interventions targeting these pathways. The roles of mitochondrial dynamics and mitochondrial function in the development of anthracycline‐induced cardiotoxicity should provide insights in devising novel strategies to attenuate the cardiac toxicity induced by anthracyclines.

MicroRNAs in Cancer Treatment-Induced Cardiotoxicity

Cancer treatment has made significant progress in the cure of different types of tumors. Nevertheless, its clinical use is limited by unwanted cardiotoxicity. Aside from the conventional chemotherapy approaches, even the most newly developed, i.e., molecularly targeted therapy and immunotherapy, exhibit a similar frequency and severity of toxicities that range from subclinical ventricular dysfunction to severe cardiomyopathy and, ultimately, congestive heart failure. Specific mechanisms leading to cardiotoxicity still remain to be elucidated. For instance, oxidative stress and DNA damage are considered key players in mediating cardiotoxicity in different treatments. microRNAs (miRNAs) act as key regulators in cell proliferation, cell death, apoptosis, and cell differentiation. Their dysregulation has been associated with adverse cardiac remodeling and toxicity. This review provides an overview of the cardiotoxicity induced by different oncologic treatments and potential miRNAs involved in this effect that could be used as possible therapeutic targets.

Anthracycline and Peripartum Cardiomyopathies

Anthracycline-associated cardiomyopathy and peripartum cardiomyopathy are nonischemic cardiomyopathies that often afflict previously healthy young patients; both diseases have been well described since at least the 1970s and both occur in the settings of predictable stressors (ie, cancer treatment and pregnancy). Despite this, the precise mechanisms and the ability to reliably predict who exactly will go on to develop cardiomyopathy and heart failure in the face of anthracycline exposure or childbirth have proven elusive. For both cardiomyopathies, recent advances in basic and molecular sciences have illuminated the complex balance between cardiomyocyte and endothelial homeostasis via 3 broad pathways: reactive oxidative stress, interference in apoptosis/growth/metabolism, and angiogenic imbalance. These advances have already shown potential for specific, disease-altering therapies, and as our mechanistic knowledge continues to evolve, further clinical successes are expected to follow.

Platycodon grandiflorum Protects Against Anthracycline-Induced Cardiotoxicity in Early Breast Cancer Patients

Background: Anthracycline-based chemotherapy is an effective treatment used for early-stage breast cancer patients. However, anthracycline use is limited due to its cardiotoxic effects. Recent studies have shown that Platycodon grandiflorum (PG) protects the heart from anthracycline-induced cardiotoxicity. However, no randomized, placebo-controlled clinical trial has been performed to investigate the clinical use of PG to prevent anthracycline-induced cardiotoxicity. This study aimed to evaluate the cardioprotective effects and safety of PG in early breast cancer patients receiving anthracycline-based chemotherapy. Methods: A total of 125 early breast cancer patients receiving anthracycline-based chemotherapy were enrolled and randomized into a PG group or placebo group in a 1:1 ratio. Results: Only 2 (3.1%) participants in the placebo group and 1 (1.6%) participant in the PG group experienced NYHA (New York Heart Association) class III or IV heart failure. There were no significant differences observed between the 2 groups. However, compared with the placebo group, patients in the PG group showed a lower incidence of subclinical heart failure (21.9% vs 8.2%, respectively, P = .033), as well as lower cardiac troponin T levels (48.4% vs 31.1%, respectively, P = .002). Importantly, there were no differences observed in the antitumor effects of anthracycline between the 2 groups (disease-free survival: hazards ratio = 1.09, 95% confidence interval = 0.45-2.62, P = .84; overall survival: hazards ratio = 1.46, 95% confidence interval = 0.33-6.43, P = .62). Conclusion: PG prevents anthracycline-induced acute and chronic cardiac injury in early-stage breast cancer patients without compromising the antitumor effects of chemotherapy.

Chrysophanol protects against doxorubicin-induced cardiotoxicity by suppressing cellular PARylation

The clinical application of doxorubicin (DOX) in cancer chemotherapy is limited by its life-threatening cardiotoxic effects. Chrysophanol (CHR), an anthraquinone compound isolated from the rhizome of Rheum palmatum L., is considered to play a broad role in a variety of biological processes. However, the effects of CHR׳s cardioprotection in DOX-induced cardiomyopathy is poorly understood. In this study, we found that the cardiac apoptosis, mitochondrial injury and cellular PARylation levels were significantly increased in H9C2 cells treated by Dox, while these effects were suppressed by CHR. Similar results were observed when PARP1 activity was suppressed by its inhibitors 3-aminobenzamide (3AB) and ABT888. Ectopic expression of PARP1 effectively blocked this CHR׳s cardioprotection against DOX-induced cardiomyocyte injury in H9C2 cells. Furthermore, pre-administration with both CHR and 3AB relieved DOX-induced cardiac apoptosis, mitochondrial impairment and heart dysfunction in Sprague-Dawley rat model. These results revealed that CHR protects against DOX-induced cardiotoxicity by suppressing cellular PARylation and provided critical evidence that PARylation may be a novel target for DOX-induced cardiomyopathy.

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.

Establishment of an in vitro cytotoxicity assay platform using primary monkey cardiomyocytes

To establish an in vitro cytotoxicity assay platform using monkey cardiomyocytes, we isolated primary cardiomyocytes from fetal cynomolgus monkeys at different gestation days (from day 39 to 90) using the trypsin and collagenase digestion method, which was identical to the standard procedure for rat cardiomyocytes. Under these conditions, the primary cells obtained from monkeys at gestation day 63 or earlier showed spontaneous beating, with >80% cells being viable from all fetuses. Transcriptome analysis of the monkey cardiomyocytes indicated that the cells have essential components of cardiac functions, such as myosins, α-actin, cardiac troponins, and calcium-related molecules. The susceptibility to doxorubicin-induced cytotoxicity in monkey cardiomyocytes was comparable to that in rat cardiomyocytes, as evaluated based on intracellular ATP levels. Microarray analysis with Ingenuity Pathway Analysis revealed that doxorubicin predominantly increased the expression of several key genes involved in the endoplasmic reticulum stress pathway in monkey cardiomyocytes than in rat cardiomyocytes. In conclusion, we isolated primary monkey cardiomyocytes that showed similar sensitivity to doxorubicin as compared with rat cardiomyocytes. This in vitro monkey cardiomyocyte assay platform would serve as a powerful tool for the investigation of the interspecies differences in drug-induced cardiotoxicity and its underlying mechanism.

Chemotherapeutic Drugs and Mitochondrial Dysfunction: Focus on Doxorubicin, Trastuzumab, and Sunitinib

Many cancer therapies produce toxic side effects whose molecular mechanisms await full elucidation. The most feared and studied side effect of chemotherapeutic drugs is cardiotoxicity. Also, skeletal muscle physiology impairment has been recorded after many chemotherapeutical treatments. However, only doxorubicin has been extensively studied for its side effects on skeletal muscle. Chemotherapeutic-induced adverse side effects are, in many cases, mediated by mitochondrial damage. In particular, trastuzumab and sunitinib toxicity is mainly associated with mitochondria impairment and is mostly reversible. Vice versa, doxorubicin-induced toxicity not only includes mitochondria damage but can also lead to a more robust and extensive cell injury which is often irreversible and lethal. Drugs interfering with mitochondrial functionality determine the depletion of ATP reservoirs and lead to subsequent reversible contractile dysfunction. Mitochondrial damage includes the impairment of the respiratory chain and the loss of mitochondrial membrane potential with subsequent disruption of cellular energetic. In a context of increased stress, AMPK has a key role in maintaining energy homeostasis, and inhibition of the AMPK pathway is one of the proposed mechanisms possibly mediating mitochondrial toxicity due to chemotherapeutics. Therapies targeting and protecting cell metabolism and energy management might be useful tools in protecting muscular tissues against the toxicity induced by chemotherapeutic drugs.

Antiangiogenic Activity of Chemopreventive Drugs

Tumors growing within the host form dynamic aberrant tissue that consists of host components, including the stroma, an expanding vasculature and often chronic inflammation, in addition to the tumor cells themselves. These host components can contribute to, rather than limit, tumor expansion, whereas deprivation of vessel formation has the potential to confine tumors in small, clinically silent foci. Therapeutic inhibition of vessel formation could be best suited to preventive strategies aimed at the suppression of angiogenesis in primary tumors in subjects at risk, or of micrometastases after surgical removal of a primary tumor. Our analysis of potential cancer chemopreventive molecules including N-acetylcysteine, green tea flavonoids and 4-hydroxyphenyl-retinamide has identified antiangiogenic activities that could account -at least in part - for the tumor prevention effects observed with these compounds. These drugs appear to target common mechanisms of tumor angiogenesis that may permit identification of critical targets for antiangiogenic therapy and antiangiogenic chemoprevention.

Protective Effects of ω-3 PUFA in Anthracycline-Induced Cardiotoxicity: A Critical Review

It has been demonstrated that ω-3 polyunsaturated fatty acids (ω-3 PUFA) may exert a beneficial role as adjuvants in the prevention and treatment of many disorders, including cardiovascular diseases and cancer. Particularly, several in vitro and in vivo preclinical studies have shown the antitumor activity of ω-3 PUFA in different kinds of cancers, and several human studies have shown that ω-3 PUFA are able to decrease the risk of a series of cardiovascular diseases. Several mechanisms have been proposed to explain their pleiotropic beneficial effects. ω-3 PUFA have also been shown to prevent harmful side-effects (including cardiotoxicity and heart failure) induced by conventional and innovative anti-cancer drugs in both animals and patients. The available literature regarding the possible protective effects of ω-3 PUFA against anthracycline-induced cardiotoxicity, as well as the mechanisms involved, will be critically discussed herein. The study will analyze the critical role of different levels of ω-3 PUFA intake in determining the results of the combinatory studies with anthracyclines. Suggestions for future research will also be considered.

Precision cardio-oncology: understanding the cardiotoxicity of cancer therapy

Current oncologic treatments have brought a strong reduction in mortality in cancer patients. However, the cancer therapy-related cardiovascular complications, in particular chemo-therapy and radiation therapy-induced cardiotoxicities are a major cause of morbidity and mortality in people living with or surviving cancer. The simple fact is that all antineoplastic agents and radiation therapy target tumor cells but also result in collateral damage to other tissues including the cardiovascular system. The commonly used anthracycline chemotherapy agents can induce cardiomyopathy and congestive heart failure. Targeted therapies with human epidermal growth factor antibodies, tyrosine kinase inhibitors or vascular endothelial growth factor antibodies, and the antimetabolites also have shown to induce cardiomyopathy and myocardial ischemia. Cardiac arrhythmias and hypertension have been well described with the use of tyrosine kinase inhibitors and antimicrotubule agents. Pericarditis can happen with the use of cyclophosphamide or cytarabine. Mediastinal radiation can cause constrictive pericarditis, myocardial fibrosis, valvular lesions, and coronary artery disease. Despite significant progresses in the understanding of the molecular and pathophysiologic mechanisms behind the cardiovascular toxicity of cancer therapy, there is still lack of evidence-based approach for the monitoring and management of patients. This review will focus mainly on the recent advances in the molecular mechanisms of cardiotoxicity related to common cancer therapies while introducing the concept of cardio-oncology service. Applying the general principles of multi-disciplinary approaches toward the diagnosis, prevention, monitoring, and treatment of cancer therapy-induced cardiomyopathy and heart failure will also be discussed.

Cardioprotective effect of Platycodon grandiflorum in patients with early breast cancer receiving anthracycline-based chemotherapy: study protocol for a randomized controlled trial

Background

Anthracyclines, alone or in combination with other drugs, are among the most effective chemotherapeutic agents to treat breast cancer both in the adjuvant and neoadjuvant setting. Unfortunately, anthracycline-associated dose-dependent cardiotoxicity is a limiting factor in clinical use. Extensive efforts have been devoted to identifying strategies to prevent anthracycline-induced cardiotoxicity. However, most cardioprotective agents have shown little effect in clinical trials. Herbal medicines are pure, natural substances that have been used for centuries in many countries, including China. This trial aims to evaluate the cardioprotective effects and safety of Platycodon grandiflorum granules compared to placebo granules in patients with early breast cancer receiving anthracycline-based chemotherapy.

Method/design

This study is a single-center, double-blinded, randomized, placebo-controlled, parallel-group trial. A total of 120 patients will be randomly allocated in a 1:1 ratio to receive either P. grandiflorum granules or placebo granules twice daily for 12 weeks. The primary outcome is heart failure (either clinical or subclinical). The secondary outcomes include all-cause mortality, cardiac death, electrocardiogram (ECG) findings, left ventricular diastolic function, longitudinal systolic strain and velocities measured by tissue Doppler imaging, cardiac biomarkers, such as troponin I (TnI), brain natriuretic peptide (BNP), and creatine kinase isoenzymes (CK-MB). Assessments will be performed at baseline (before randomization) and 3, 6, 9, 12, 16, and 20 weeks after randomization.

Discussion

This will be the first clinical trial to evaluate the cardioprotective effects and safety of P. grandiflorum in patients with early breast cancer receiving anthracycline-based chemotherapy. We are also performing this trial to assess the feasibility of a larger-scale clinical trial in the future.

Trail registration

Chinese Clinical Trial Registry, ChiCTR-IPR-16009256. Registered on 23 September 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2140-z) contains supplementary material, which is available to authorized users.

The effect of N-acetylcysteine (NAC) on human cognition - A systematic review

Oxidative stress, neuroinflammation and neurogenesis are commonly implicated as cognitive modulators across a range of disorders. N-acetylcysteine (NAC) is a glutathione precursor with potent antioxidant, pro-neurogenesis and anti-inflammatory properties and a favourable safety profile. A systematic review of the literature specifically examining the effect of NAC administration on human cognition revealed twelve suitable articles for inclusion: four examining Alzheimer's disease; three examining healthy participants; two examining physical trauma; one examining bipolar disorder, one examining schizophrenia, and one examining ketamine-induced psychosis. Heterogeneity of studies, insufficiently powered studies, infrequency of cognition as a primary outcome, heterogeneous methodologies, formulations, co-administered treatments, administration regimes, and assessment confounded the drawing of firm conclusions. The available data suggested statistically significant cognitive improvements following NAC treatment, though the paucity of NAC-specific research makes it difficult to determine if this effect is meaningful. While NAC may have a positive cognitive effect in a variety of contexts; larger, targeted studies are warranted, specifically evaluating its role in other clinical disorders with cognitive sequelae resulting from oxidative stress and neuroinflammation.

Anthracycline Chemotherapy and Cardiotoxicity

Anthracycline chemotherapy maintains a prominent role in treating many forms of cancer. Cardiotoxic side effects limit their dosing and improved cancer outcomes expose the cancer survivor to increased cardiovascular morbidity and mortality. The basic mechanisms of cardiotoxicity may involve direct pathways for reactive oxygen species generation and topoisomerase 2 as well as other indirect pathways. Cardioprotective treatments are few and those that have been examined include renin angiotensin system blockade, beta blockers, or the iron chelator dexrazoxane. New treatments exploiting the ErbB or other novel pro-survival pathways, such as conditioning, are on the cardioprotection horizon. Even in the forthcoming era of targeted cancer therapies, the substantial proportion of today's anthracycline-treated cancer patients may become tomorrow's cardiac patient.

Oncocardiology-Past, Present, and Future: A Review

Importance

Oncocardiology is a medical discipline that focuses on the identification, prevention, and treatment of cardiovascular complications related to cancer therapy. This discipline has gained interest from the cardiology community in recent years because of a remarkable increase in the number of cancer survivors and the proliferation of new cancer therapies causing cardiovascular complications, such as hypertension, heart failure, vascular complications, and cardiac arrhythmia. In this review, we provide historical perspectives, highlight new discoveries, and speculate on the opportunity created by merging the research interests and clinical practices of cardiology and oncology.

Observations

The old paradigm of anthracycline cardiotoxic effects is replaced by new insights that anthracycline targets topoisomerase II β to cause DNA double-strand breaks and a profound change in the transcriptome leading to the generation of reactive oxygen species and the development of mitochondriopathy. Prevention of anthracycline cardiotoxic effects should be based on inhibiting or degrading topoisomerase II β. New challenges were posed by the introduction of trastuzumab and tyrosine kinase inhibitors that revolutionized cancer therapy. The on-target cardiotoxic effects of trastuzumab were owing to a prosurvival benefit of Her2 that binds to neuregulin, whereas the off-target effect of multitargeted tyrosine kinase inhibitors may be mediated by disruption of the vascular endothelial growth factor signaling pathway or the stress-induced angiogenesis. Sensitive imaging techniques, such as global strain, and biomarkers have allowed for early detection of cardiotoxic effects. Early treatment with heart failure medications may be beneficial in preventing the development of late cardiotoxic effects.

Conclusions and Relevance

Close collaboration between cardiologists and oncologists is required to meet the demand of an increasing number of cancer survivors. New insights based on mechanistic studies or genetic discoveries will pave the way for better prevention, diagnosis, and treatment of cancer therapy-induced cardiovascular complications.

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.

Drug Resistance of Endocardial Endothelial Cells is Related to Higher Endogenous ABCG2

Endocardial endothelial cells (EECs), when compared with endothelial cells of arteries and veins, possess higher resistance to apoptosis-inducing anticancer agents. The mechanism of this resistance property is unknown. We have investigated the molecular mechanism, which contributes to increased cell survival capacity in EECs. We explored whether the resistance to apoptosis is associated with the cellular expression of ATP-binding cassette transporters such as P-glycoprotein, MRP-1, and ABCG2. We used primary and immortalized porcine endocardial endothelial cells (PEECs and hTERT PEECs) and compared the results with that in porcine aortic endothelial cells (PAECs), left atrioventricular valve endothelial cells (PVECs), and human umbilical vein endothelial cell line (EA.hy926). FACS and immunoblot analysis revealed a significantly higher expression of ABCG2 in PEECs and hTERT PEECs compared to PAECs, PVECs, and EA.hy926. Using apoptosis-inducing anticancer agents such as doxorubicin and camptothecin, through chromatin condensation assay and immunoblot analysis, we demonstrated a higher resistance to apoptosis in EECs compared to PAECs, PVECs, and EA.hy926. Interestingly, resistance in EECs reversed in presence of ABCG2 specific inhibitor, fumitremorgin C. Our observations suggest that an inherently high expression of ABCG2 in EECs protects them against apoptosis in presence of anticancer agents.

High Throughput Screening Identifies a Novel Compound Protecting Cardiomyocytes from Doxorubicin-Induced Damage

Antracyclines are effective antitumor agents. One of the most commonly used antracyclines is doxorubicin, which can be successfully used to treat a diverse spectrum of tumors. Application of these drugs is limited by their cardiotoxic effect, which is determined by a lifetime cumulative dose. We set out to identify by high throughput screening cardioprotective compounds protecting cardiomyocytes from doxorubicin-induced injury. Ten thousand compounds of ChemBridge's DIVERSet compound library were screened to identify compounds that can protect H9C2 rat cardiomyocytes against doxorubicin-induced cell death. The most effective compound proved protective in doxorubicin-treated primary rat cardiomyocytes and was further characterized to demonstrate that it significantly decreased doxorubicin-induced apoptotic and necrotic cell death and inhibited doxorubicin-induced activation of JNK MAP kinase without having considerable radical scavenging effect or interfering with the antitumor effect of doxorubicin. In fact the compound identified as 3-[2-(4-ethylphenyl)-2-oxoethyl]-1,2-dimethyl-1H-3,1-benzimidazol-3-ium bromide was toxic to all tumor cell lines tested even without doxorubicine treatment. This benzimidazole compound may lead, through further optimalization, to the development of a drug candidate protecting the heart from doxorubicin-induced injury.

Dihydromyricetin prevents cardiotoxicity and enhances anticancer activity induced by adriamycin

Adriamycin, a widely used anthracycline antibiotic in multiple chemotherapy regimens, has been challenged by the cardiotoxicity leading to fatal congestive heart failure in the worst condition. The present study demonstrated that Dihydromyricetin, a natural product extracted from ampelopsis grossedentat, exerted cardioprotective effect against the injury in Adriamycin-administrated ICR mice. Dihydromyricetin decreased ALT, LDH and CKMB levels in mice serum, causing a significant reduction in the toxic death triggered by Adriamycin. The protective effects were also indicated by the alleviation of abnormal electrocardiographic changes, the abrogation of proliferation arrest and apoptotic cell death in primary myocardial cells. Further study revealed that Dihydromyricetin-rescued loss of anti-apoptosis protein ARC provoked by Adriamycin was involved in the cardioprotection. Intriguingly, the anticancer activity of Adriamycin was not compromised upon the combination with Dihydromyricetin, as demonstrated by the enhanced anticancer effect achieved by Adriamycin plus Dihydromyricetin in human leukemia U937 cells and xenograft models, in a p53-dependent manner. These results collectively promised the potential value of Dihydromyricetin as a rational cardioprotective agent of Adriamycin, by protecting myocardial cells from apoptosis, while potentiating anticancer activities of Adriamycin, thus further increasing the therapeutic window of the latter one.

Prevention of anthracycline-induced cardiotoxicity: challenges and opportunities

Anthracycline compounds are major culprits in chemotherapy-induced cardiotoxicity, which is the chief limiting factor in delivering optimal chemotherapy to cancer patients. Although extensive efforts have been devoted to identifying strategies to prevent anthracycline-induced cardiotoxicity, there is little consensus regarding the best approach. Recent advances in basic mechanisms of anthracycline-induced cardiotoxicity provided a unified theory to explain the old reactive-oxygen species hypothesis and identified topoisomerase 2β as the primary molecular target for cardioprotection. This review outlines current strategies for primary and secondary prevention of anthracycline-induced cardiotoxicity resulting from newly recognized molecular mechanisms and identifies knowledge gaps requiring further investigation.

N-acetylcysteine reduces oxidative stress, nuclear factor‑κB activity and cardiomyocyte apoptosis in heart failure

The roles of oxidative stress on nuclear factor (NF)‑κB activity and cardiomyocyte apoptosis during heart failure were examined using the antioxidant N‑acetylcysteine (NAC). Heart failure was established in Japanese white rabbits with intravenous injections of doxorubicin, with ten rabbits serving as a control group. Of the rabbits with heart failure, 12 were not treated (HF group) and 13 received NAC (NAC group). Cardiac function was assessed using echocardiography and hemodynamic analysis. Myocardial cell apoptosis, apoptosis‑related protein expression, NF‑κBp65 expression and activity, total anti‑oxidative capacity (tAOC), 8‑iso‑prostaglandin F2α (8‑iso‑PGF2α) expression and glutathione (GSH) expression levels were determined. In the HF group, reduced tAOC, GSH levels and Bcl‑2/Bax ratios as well as increased 8‑iso‑PGF2α levels and apoptosis were observed (all P<0.05), which were effects that were attenuated by the treatment with NAC. NF‑κBp65 and iNOS levels were significantly higher and the P‑IκB‑α levels were significantly lower in the HF group; expression of all three proteins returned to pre‑HF levels following treatment with NAC. Myocardial cell apoptosis was positively correlated with left ventricular end-diastolic pressure (LVEDP), NF‑κBp65 expression and 8‑iso‑PGF2α levels, but negatively correlated with the maximal and minimal rates of increase in left ventricular pressure (+dp/dtmax and ‑dp/dtmin, respectively) and the Bcl‑2/Bax ratio (all P<0.001). The 8‑iso‑PGF2α levels were positively correlated with LVEDP and negatively correlated with +dp/dtmax and ‑dp/dtmin (all P<0.001). The present study demonstrated that NAC increased the antioxidant capacity, decreased the NF‑κB activation and reduced myocardial cell apoptosis in an in vivo heart failure model.

Topoisomerase 2β: a promising molecular target for primary prevention of anthracycline-induced cardiotoxicity

Anthracyclines are powerful chemotherapy agents that are still widely used today. However, their clinical use is limited by the development of dose-dependent cardiotoxicity. Recently, we showed that topoisomerase 2β (Top2β) is required for anthracycline to induce DNA double-strand breaks and changes in the transcriptome, leading to mitochondrial dysfunction and generation of reactive oxygen species. Furthermore, deleting Top2β from cardiomyocytes prevented the development of anthracycline-induced cardiotoxicity in mice. On the basis of this molecular insight, new strategies should be developed to prevent anthracycline-induced cardiotoxicity. First, Top2α-specific anthracyclines should be tested to determine whether they will spare the heart. Second, Top2β should be studied as a potential biomarker to predict risk of developing cardiotoxicity before anthracycline treatment. Third, inhibiting and deleting Top2β in the heart should also be tested as primary prevention strategies. We propose that Top2β is a promising molecular target that can be used to design interventions to prevent anthracycline-induced cardiotoxicity.

Early and delayed cardioprotective intervention with dexrazoxane each show different potential for prevention of chronic anthracycline cardiotoxicity in rabbits

Despite incomplete understanding to its mechanism of action, dexrazoxane (DEX) is still the only clearly effective cardioprotectant against chronic anthracycline (ANT) cardiotoxicity. However, its clinical use is currently restricted to patients exceeding significant ANT cumulative dose (300mg/m(2)), although each ANT cycle may induce certain potentially irreversible myocardial damage. Therefore, the aim of this study was to compare early and delayed DEX intervention against chronic ANT cardiotoxicity and study the molecular events involved. The cardiotoxicity was induced in rabbits with daunorubicin (DAU; 3mg/kg/week for 10 weeks); DEX (60mg/kg) was administered either before the 1st or 7th DAU dose (i.e. after ≈300mg/m(2) cumulative dose). While both DEX administration schedules prevented DAU-induced premature deaths and severe congestive heart failure, only the early intervention completely prevented the left ventricular dysfunction, myocardial morphological changes and mitochondrial damage. Further molecular analyses did not support the assumption that DEX cardioprotection is based and directly proportional to protection from DAU-induced oxidative damage and/or deletions in mtDNA. Nevertheless, DAU induced significant up-regulation of heme oxygenase 1 pathway while heme synthesis was inversely regulated and both changes were schedule-of-administration preventable by DEX. Early and delayed DEX interventions also differed in ability to prevent DAU-induced down-regulation of expression of mitochondrial proteins encoded by both nuclear and mitochondrial genome. Hence, the present functional, morphological as well as the molecular data highlights the enormous cardioprotective effects of DEX and provides novel insights into the molecular events involved. Furthermore, the data suggests that currently recommended delayed intervention may not be able to take advantage of the full cardioprotective potential of the drug.

Oxidative stress, redox signaling, and metal chelation in anthracycline cardiotoxicity and pharmacological cardioprotection

SIGNIFICANCE

Anthracyclines (doxorubicin, daunorubicin, or epirubicin) rank among the most effective anticancer drugs, but their clinical usefulness is hampered by the risk of cardiotoxicity. The most feared are the chronic forms of cardiotoxicity, characterized by irreversible cardiac damage and congestive heart failure. Although the pathogenesis of anthracycline cardiotoxicity seems to be complex, the pivotal role has been traditionally attributed to the iron-mediated formation of reactive oxygen species (ROS). In clinics, the bisdioxopiperazine agent dexrazoxane (ICRF-187) reduces the risk of anthracycline cardiotoxicity without a significant effect on response to chemotherapy. The prevailing concept describes dexrazoxane as a prodrug undergoing bioactivation to an iron-chelating agent ADR-925, which may inhibit anthracycline-induced ROS formation and oxidative damage to cardiomyocytes.

RECENT ADVANCES

A considerable body of evidence points to mitochondria as the key targets for anthracycline cardiotoxicity, and therefore it could be also crucial for effective cardioprotection. Numerous antioxidants and several iron chelators have been tested in vitro and in vivo with variable outcomes. None of these compounds have matched or even surpassed the effectiveness of dexrazoxane in chronic anthracycline cardiotoxicity settings, despite being stronger chelators and/or antioxidants.

CRITICAL ISSUES

The interpretation of many findings is complicated by the heterogeneity of experimental models and frequent employment of acute high-dose treatments with limited translatability to clinical practice.

FUTURE DIRECTIONS

Dexrazoxane may be the key to the enigma of anthracycline cardiotoxicity, and therefore it warrants further investigation, including the search for alternative/complementary modes of cardioprotective action beyond simple iron chelation.

Chemotherapy-induced weakness and fatigue in skeletal muscle: the role of oxidative stress

SIGNIFICANCE

Fatigue is one of the most common symptoms of cancer and its treatment, manifested in the clinic through weakness and exercise intolerance. These side effects not only compromise patient's quality of life (QOL), but also diminish physical activity, resulting in limited treatment and increased morbidity.

RECENT ADVANCES

Oxidative stress, mediated by cancer or chemotherapeutic agents, is an underlying mechanism of the drug-induced toxicity. Nontargeted tissues, such as striated muscle, are severely affected by oxidative stress during chemotherapy, leading to toxicity and dysfunction.

CRITICAL ISSUES

These findings highlight the importance of investigating clinically applicable interventions to alleviate the debilitating side effects. This article discusses the clinically available chemotherapy drugs that cause fatigue and oxidative stress in cancer patients, with an in-depth focus on the anthracycline doxorubicin. Doxorubicin, an effective anticancer drug, is a primary example of how chemotherapeutic agents disrupt striated muscle function through oxidative stress.

FUTURE DIRECTIONS

Further research investigating antioxidants could provide relief for cancer patients from debilitating muscle weakness, leading to improved quality of life.

In vivo and in vitro assessment of the role of glutathione antioxidant system in anthracycline-induced cardiotoxicity

The clinical usefulness of anthracycline antineoplastic drugs is limited by their cardiotoxicity. Its mechanisms have not been fully understood, although the induction of oxidative stress is widely believed to play the principal role. Glutathione is the dominant cellular antioxidant, while glutathione peroxidase (GPx) together with glutathione reductase (GR) constitutes the major enzymatic system protecting the cardiac cells from oxidative damage. Therefore, this study aimed to assess their roles in anthracycline cardiotoxicity. Ten-week intravenous administration of daunorubicin (DAU, 3 mg/kg weekly) to rabbits induced heart failure, which was evident from decreased left ventricular ejection fraction and release of cardiac troponins to circulation. However, no significant changes in either total or oxidized glutathione contents or GR activity were detected in left ventricular tissue of DAU-treated rabbits when compared with control animals. GPx activity in the cardiac tissue significantly increased. In H9c2 rat cardiac cells, 24-h DAU exposure (0.1-10 μM) induced significant dose-dependent toxicity. Cellular content of reduced glutathione was insignificantly decreased, oxidized glutathione and GR activity were unaffected, and GPx activity was significantly increased. Neither buthionine sulfoximine (BSO, glutathione biosynthesis inhibitor) nor 2-oxo-4-thiazolidine-carboxylic acid (OTC, glutathione biosynthetic precursor) had significant effects on DAU cytotoxicity. This contrasted with model oxidative injury induced by hydrogen peroxide, which cytotoxicity was increased by BSO and decreased by OTC. In conclusion, our results suggest that the dysfunction of glutathione antioxidant system does not play a causative role in anthracycline cardiotoxicity.

Cardiotoxicity of anticancer drugs: the need for cardio-oncology and cardio-oncological prevention

Due to the aging of the populations of developed countries and a common occurrence of risk factors, it is increasingly probable that a patient may have both cancer and cardiovascular disease. In addition, cytotoxic agents and targeted therapies used to treat cancer, including classic chemotherapeutic agents, monoclonal antibodies that target tyrosine kinase receptors, small molecule tyrosine kinase inhibitors, and even antiangiogenic drugs and chemoprevention agents such as cyclooxygenase-2 inhibitors, all affect the cardiovascular system. One of the reasons is that many agents reach targets in the microenvironment and do not affect only the tumor. Combination therapy often amplifies cardiotoxicity, and radiotherapy can also cause heart problems, particularly when combined with chemotherapy. In the past, cardiotoxic risk was less evident, but it is increasingly an issue, particularly with combination therapy and adjuvant therapy. Today's oncologists must be fully aware of cardiovascular risks to avoid or prevent adverse cardiovascular effects, and cardiologists must now be ready to assist oncologists by performing evaluations relevant to the choice of therapy. There is a need for cooperation between these two areas and for the development of a novel discipline, which could be termed cardio-oncology or onco-cardiology. Here, we summarize the potential cardiovascular toxicities for a range of cancer chemotherapeutic and chemopreventive agents and emphasize the importance of evaluating cardiovascular risk when patients enter into trials and the need to develop guidelines that include collateral effects on the cardiovascular system. We also discuss mechanistic pathways and describe several potential protective agents that could be administered to patients with occult or overt risk for cardiovascular complications.