Inhibition of ErbB2/neuregulin signaling augments paclitaxel-induced cardiotoxicity in adult ventricular myocytes

A new perspective in the prevention and treatment of antitumor therapy-related cardiotoxicity: Intestinal microecology

The continuous development of antitumor therapy has significantly reduced the mortality of patients with malignancies. However, the antitumor-related cardiotoxicity has become the leading cause of long-term mortality in patients with malignancies. Besides, the pathogenesis of antitumor-related cardiotoxicity is still unclear, and practical means of prevention and treatment are lacking in clinical practice. Therefore, the major challenge is how to combat the cardiotoxicity of antitumor therapy effectively. More and more studies have shown that antitumor therapy kills tumor cells while causing damage to sensitive tissues such as the intestinal mucosa, leading to the increased permeability of the intestine and the dysbiosis of intestinal microecology. In addition, the dysbiosis of intestinal microecology contributes to the development and progression of cardiovascular diseases through multiple pathways. Thus, the dysbiosis of intestinal microecology may be a potential mechanism and target for antitumor-related cardiotoxicity. We summarized the characteristics of intestinal microecology disorders induced by antitumor therapy and the association between intestinal microecological dysbiosis and CVD. And on this basis, we hypothesized the potential mechanisms of intestinal microecology mediating the occurrence of antitumor-related cardiotoxicity. Then we reviewed the previous studies targeting intestinal microecology against antitumor-associated cardiotoxicity, aiming to provide a reference for future studies on the occurrence and prevention of antitumor-related cardiotoxicity by intestinal microecology.

Evaluation of Expression Level of miR-3135b-5p in Blood Samples of Breast Cancer Patients Experiencing Chemotherapy-Induced Cardiotoxicity

The efficacy of chemotherapeutics in the treatment of breast cancer is limited by cardiotoxicity, which could lead to irreversible heart failure. The evaluation of miRNA levels as a vital biomarker could predict cardiotoxicity induced by chemotherapy. According to our previous meta-analysis study on patients with heart failure, we found that miR-3135b had a significant increase in patients with heart failure. Therefore, the present study aimed to evaluate the expression level of miR-3135b in the blood sample of patients experiencing chemotherapy-induced cardiotoxicity. Blood samples were collected from breast cancer patients or breast cancer patients who had received chemotherapy and had not experienced any chemotherapy-induced cardiotoxicity (N = 37, control group) and breast cancer patients experiencing chemotherapy-induced cardiotoxicity after chemotherapy (N = 33). The expression level of miR-3135b was evaluated using real-time polymerase chain reaction (RT-PCR). The 2-ΔCt values of miR-3135b were compared between two groups. We observed a significant increase in the expression level of miR-3135b between patients experiencing chemotherapy-induced cardiotoxicity and the control group (P = 0.0001). Besides, the ejection fraction parameter was correlated with the expression level of miR-3135b (r = 0.5 and P = 0.0001). To sum up, miR-3135b might be useful as a promising circulating biomarker in predicting cardiotoxicity induced by chemotherapy. However, more studies are needed to validate miR-3135b as a biomarker for the diagnosis of chemotherapy-induced cardiotoxicity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12291-022-01075-3.

Mechanisms of trastuzumab induced cardiotoxicity - is exercise a potential treatment?

The use of the adjuvant therapeutic antibody trastuzumab in breast cancer is associated with a range of cardiotoxic side effects despite successfully reducing the severity of outcomes cancer patients,. The most common cardiac effect, a reduction in left ventricular ejection fraction (LVEF), is a known precursor to heart failure and often requires interruption of chemotherapy to avoid endangering patients further. An understanding of trastuzumab's cardiac-specific interactions is therefore critical in devising new methods to not only avoid permanent cardiac damage, but also prolong treatment time, and therefore effectiveness, for breast cancer patients. Increasingly, the use of exercise as a treatment has been indicated across the field of cardio-oncology due to encouraging evidence that it can protect against LVEF reductions and heart failure. This review explores the mechanisms of trastuzumab-mediated cardiotoxicity, as well as the physiological effects of exercise on the heart, in order to assess the suitability of exercise intervention for breast cancer patients on trastuzumab antibody-therapy. We furthermore draw comparison to existing evidence for exercise intervention as a cardioprotective treatment in doxorubicin-induced cardiotoxicity. Although preclinical evidence seems to support exercise-based approaches also in trastuzumab-cardiotoxicity, current clinical evidence is too limited to confidently recommend it as a treatment, largely owing to issues of adherence. Future studies should therefore examine how the variety and duration of exercise can be adjusted to improve treatment effectiveness at a more personalised level.

The Preventive Effects of Naringin and Naringenin against Paclitaxel-Induced Nephrotoxicity and Cardiotoxicity in Male Wistar Rats

This study assessed the preventive properties of naringin and naringenin on paclitaxel-induced nephrotoxicity and cardiotoxicity in adult male Wistar rats. Intraperitoneal injection of paclitaxel 2 mg/kg body weight, two days/week on the 2nd and 5th days of each week, with or without oral administration of naringin and/or naringenin 10 mg/kg body weight every other day, was continued for six weeks. Treatment of rats with naringin and/or naringenin significantly reversed elevated serum creatinine, urea, and uric acid levels caused by paclitaxel, reflecting improved kidney function. Similarly, heart dysfunction induced by paclitaxel was alleviated after treatment with naringin and/or naringenin, as evidenced by significant decreases in elevated CK-MB and LDH activities. After drug administration, histopathological findings and lesion scores in the kidneys and heart were markedly decreased by naringin and/or naringenin. Moreover, the treatments reversed renal and cardiac lipid peroxidation and the negative impacts on antioxidant defenses via raising GSH, SOD, and GPx. The preventive effects of naringin and naringenin were associated with suppressing oxidative stress and reestablishing antioxidant defenses. A combination of naringin and naringenin was the most efficacious in rescuing organ function and structure.

Cardiovascular Toxicity With PD-1/PD-L1 Inhibitors in Cancer Patients: A Systematic Review and Meta-Analysis

Background

PD-1/PD-L1 inhibitors have significantly improved the outcomes of those patients with various malignancies. However, the incidence of adverse events also increased. This meta-analysis aims to systematically evaluate the risk of cardiovascular toxicity in patients treated with PD-1/PD-L1 inhibitors.

Materials and methods

We searched PubMed, Embase, the Cochrane Library databases for all randomized controlled trials (RCTs) comparing all-grade and grade 3-5 cardiovascular toxicity of single-agent PD-1/PD-L1 inhibitors to placebo/chemotherapy, PD-1/PD-L1 inhibitors combined with chemotherapy to chemotherapy, or PD-1/PD-L1 inhibitors combined with CTLA-4 inhibitors to single-agent immune checkpoint inhibitors (ICIs) and pooled our data in a meta-analysis stratified by tumor types and PD-1 or PD-L1 inhibitors. The Mantel-Haenszel method calculated the odds ratio (OR) and its corresponding 95% confidence intervals (CIs).

Results

A total of 50 trials were included in the analysis. Single-agent PD-1/PD-L1 inhibitors increased the risk of all-grade cardiotoxicity compared with placebo (OR=2.11, 95%CI 1.02-4.36, P=0.04). Compared with chemotherapy, patients receiving PD-1/PD-L1 inhibitors combined with chemotherapy had a significant higher risk of all-grade (OR=1.53, 95%CI 1.18-1.99, P=0.001) and grade 3-5 cardiotoxicity (OR=1.63, 95%CI 1.11-2.39, P=0.01) cardiotoxicity, especially patients with non-small cell lung cancer (NSCLC) [all-grade cardiotoxicity (OR=1.97, 95%CI 1.14-3.41, P=0.02) and grade 3-5 cardiotoxicity (OR=2.15, 95%CI 1.08-4.27, P=0.03)]. Subgroup analysis showed that PD-1 inhibitors combined with chemotherapy were associated with a higher risk of grade 3-5 cardiotoxicity (OR=2.08, 95%CI 1.18-3.66, P=0.01). Compared with placebo or chemotherapy, single-agent PD-1/PD-L1 inhibitors did not increase the risk of all-grade of myocarditis, arrhythmia and hypertension. However, PD-1/PD-L1 inhibitors combined with chemotherapy increased the risk of all-grade arrhythmia (OR=1.63, 95%CI 1.07-2.46, P=0.02) [PD-L1 inhibitor-containing treatment (OR=1.75, 95%CI 1.09-2.80, P=0.02)], and the risk of all-grade hypertension (OR=1.34, 95%CI 1.02-1.77, P=0.04) and grade 3-5 hypertension (OR=1.54, 95%CI 1.10-2.15, P=0.01).

Conclusions

Our results suggest that single-agent PD-1/PD-L1 inhibitors increase the risk of all-grade cardiotoxicity, PD-1/PD-L1 inhibitors combined with chemotherapy increase the risk of all-grade and grade 3-5 cardiotoxicity, especially in those patients treated with PD-1 inhibitor-containing treatment and those with NSCLC. In addition, PD-1/PD-L1 inhibitors combined with chemotherapy increase the risk of arrhythmia and hypertension. Therefore, this evidence should be considered when assessing the benefits and risks of PD-1/PD-L1 inhibitors in treating malignancies.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022303115.

Herceptin-Mediated Cardiotoxicity: Assessment by Cardiovascular Magnetic Resonance

Herceptin (trastuzumab) is a recombinant, humanized, monoclonal antibody that targets the human epidermal growth factor receptor 2 (HER2) and is used in the treatment of HER2-positive breast and gastric cancers. However, it carries a risk of cardiotoxicity, manifesting as left ventricular (LV) systolic dysfunction, conventionally assessed for by transthoracic echocardiography. Clinical surveillance of cardiac function and discontinuation of trastuzumab at an early stage of LV systolic dysfunction allow for the timely initiation of heart failure drug therapies that can result in the rapid recovery of cardiac function in most patients. Often considered the reference standard for the noninvasive assessment of cardiac volume and function, cardiac magnetic resonance (CMR) imaging has superior reproducibility and accuracy compared to other noninvasive imaging modalities. However, due to limited availability, it is not routinely used in the serial assessment of cardiac function in patients receiving trastuzumab. In this article, we review the diagnostic and prognostic role of CMR in trastuzumab-mediated cardiotoxicity.

Trastuzumab-Induced Negative Chronotropic and Lusitropic Effects in Cynomolgus Monkeys

ABSTRACT

Treatment with trastuzumab, an antihuman epidermal growth factor receptor type 2 humanized monoclonal antibody, has been associated with heart failure in certain patients with cancer; however, the mechanism underlying trastuzumab-induced cardiac dysfunction remains unclear. This study was conducted to clarify the cardiac effects of trastuzumab in cynomolgus monkeys, which are commonly used as cross-reactive species in preclinical safety evaluation. Monkeys were treated with trastuzumab weekly for 1 month (5 doses in total). At first and fifth doses for pressure-volume loop analysis, trastuzumab at 20 mg·kg-1·10 min-1, equivalent to the human therapeutic dose, was administered intravenously to isoflurane-anesthetized animals, followed by 60 mg·kg-1·10 min-1 at a 30-minute interval. The other doses were fixed at 80 mg·kg-1·10 min-1 under unanesthetized conditions. After the first dose, reduced heart rate, decreases in maximal rate of fall of left ventricular pressure, and prolonged time constant for isovolumic relaxation, which are predictors of drug-induced changes in lusitropy, were observed at 20 and 60 mg·kg-1. The changes after the fifth dose were comparable with those after the first dose, indicating trastuzumab did not show exacerbation of cardiac function during the 1-month trial. No significant changes in slope of preload recruitable stroke work, which is a load-independent inotropic parameter, were observed at either dose. In conclusion, trastuzumab-induced little inotropic effect but induced negative chronotropic or lusitropic effects in monkeys, which might be associated with impaired left ventricular diastolic function.

Cardiotoxicity of Epidermal Growth Factor Receptor 2-Targeted Drugs for Breast Cancer

Breast cancer is the most common form of cancer in women and its incidence has been increasing over the years. Human epidermal growth factor receptor 2 (HER2 or ErbB2) overexpression is responsible for 20 to 25% of invasive breast cancers, and is associated with poor prognosis. HER2-targeted therapy has significantly improved overall survival rates in patients with HER2-positive breast cancer. However, despite the benefits of this therapy, its cardiotoxicity is a major concern, especially when HER2-targeted therapy is used in conjunction with anthracyclines. At present, the mechanism of this cardiotoxicity is not fully understood. It is thought that HER2-targeting drugs inhibit HER2/NRG 1 dimer formation, causing an increase in ROS in the mitochondria of cardiomyocytes and inhibiting the PI3K/Akt and Ras/MAPK pathways, resulting in cell apoptosis. Antioxidants, ACE inhibitors, angiotensin II receptor blockers, β-blockers, statins and other drugs may have a cardioprotective effect when used with ErbB2-targeting drugs. NT-proBNP can be used to monitor trastuzumab-induced cardiotoxicity during HER2-targeted treatment and may serve as a biological marker for clinical prediction of cardiotoxicity. Measuring NT-proBNP is non-invasive, inexpensive and reproducible, therefore is worthy of the attention of clinicians. The aim of this review is to discuss the potential mechanisms, clinical features, diagnostic strategies, and intervention strategies related to cardiotoxicity of ErbB2-targeting drugs.

Anticancer Drug-Induced Cardiotoxicity: Insights and Pharmacogenetics

The advancement in therapy has provided a dramatic improvement in the rate of recovery among cancer patients. However, this improved survival is also associated with enhanced risks for cardiovascular manifestations, including hypertension, arrhythmias, and heart failure. The cardiotoxicity induced by chemotherapy is a life-threatening consequence that restricts the use of several chemotherapy drugs in clinical practice. This article addresses the prevalence of cardiotoxicity mediated by commonly used chemotherapeutic and immunotherapeutic agents. The role of susceptible genes and radiation therapy in the occurrence of cardiotoxicity is also reviewed. This review also emphasizes the protective role of antioxidants and future perspectives in anticancer drug-induced cardiotoxicities.

Current opinion on the pharmacogenomics of paclitaxel-induced toxicity

Introduction: Paclitaxel is a microtubule stabilizer that is currently one of the most utilized chemotherapeutic agents. Its efficacy in breast, uterine, lung and other neoplasms made its safety profile enhancement a subject of great interest. Neurotoxicity is the most common paclitaxel-associated toxicities. In addition, hypersensitivity reactions, hematological, gastrointestinal, and cardiac toxicities are all encountered.Areas covered: The current review explores paclitaxel-induced toxicities mechanisms and risk factors. Studies investigating these toxicities pharmacogenomic biomarkers are reviewed and summarized. There is a limited margin of consistency between the retrieved associations. Variants in genes related to neuro-sensitivity are the most promising candidates for future studies.Expert opinion: Genome-wide association studies highlighted multiple-candidate biomarkers relevant to neuro-sensitivity. Most of the identified paclitaxel-neurotoxicity candidate genes are derived from congenital neuropathy and diabetic-induced neurotoxicity pathways. Future studies should explore these sets of genes while considering the multifactorial nature of paclitaxel-induced neurotoxicity. In the absence of certain paclitaxel-toxicity biomarkers, future research should avoid earlier studies' caveats. Genes in paclitaxel's pharmacokinetic pathways could not provide consistent results in any of its associated toxicities. There is a need to dig deeper into toxicity-development mechanisms and personal vulnerability factors, rather than targeting only the genes suspected to affect drug exposure.

The mechanistic insights of the arrhythmogenic effect of trastuzumab

Cardiovascular diseases and cancers are the leading causes of deaths globally, and an increasing proportion of cancer patients is suffering from cardiac adverse effects of chemotherapeutic drugs. Trastuzumab, a monoclonal antibody that inhibits the activity of the human epidermal growth factor receptor 2 (HER2), is a potent targeted therapy for HER2-positive malignancies. Despite the impressive antineoplastic efficacy, the cardiotoxicity of trastuzumab frequently limits its use. Trastuzumab-induced cardiac contractile dysfunction has been extensively studied, yet the electrophysiological side effect of trastuzumab remains poorly characterized. Growing evidence from basic and clinical studies supports the link between trastuzumab treatment and arrhythmias. This review comprehensively summarizes relevant information from those reports, discusses their limitations, and suggests future research directions. We aim to encourage further investigations that will provide valuable insights to devise cardioprotective strategies against trastuzumab-induced cardiotoxicity.

Conventional cardiac risk factors associated with trastuzumab-induced cardiotoxicity in breast cancer: Systematic review and meta-analysis

BACKGROUND

Trastuzumab has had a major impact on the treatment of human epidermal growth factor receptor 2 (HER2) positive breast cancer patients. However, it is associated with cardiotoxicity, expressed as an asymptomatic decrease in left ventricular ejection fraction (LVEF) and less often as clinical HF. The aim of this meta-analysis is to identify the association of conventional cardiovascular risk factors with the development of trastuzumab-induced cardiotoxicity (TIC).

METHODS

A literature search of PubMed was conducted to identify studies examining the association between cardiovascular risk factors and TIC. Data were extracted and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated examining the odds of developing TIC for each of the risk factors.

RESULTS

A total of 35 studies were included in the analysis. Age (OR:0.7; 95%CI 0.318-1.09; P= 0.0004), hypertension (OR:0.69; 95%CI 0.26-1.12; P = 0.001), smoking(OR:0.35; 95%CI 0.01- 0.69; P = 0.038), diabetes mellitus (OR:0.44; 95%CI 0.24- 0.68; P = 0.0001) and family history of CAD (OR:5.51, 95%CI 1.76-17.25; P< 0.00001)were significantly associated with the development of cardiotoxicity. Known history of CAD (OR: 3.72; 95%CI 2.11-6.57; P = 0.0005) was also associated with the development of TIC.

CONCLUSION(S)

Identifying women at risk for TIC have several important potential applications. Clinicians may decide to assess LVEF more frequently in patients at highest risk for TIC in order to detect LV systolic dysfunction earlier. Additionally, this could help identify patients who would benefit most from prophylactic therapy for preventing TIC.

Microtubule Inhibitors and Cardiotoxicity

PURPOSE OF REVIEW

Cancer and heart disease are the leading causes of mortality in the USA. Advances in cancer therapies, namely, the development and use of chemotherapeutic agents alone or in combination, are becoming increasingly prevalent.

RECENT FINDINGS

Many chemotherapeutic agents have been associated with adverse cardiovascular manifestations. The mechanisms of these sequelae remain incompletely understood. In particular, microtubule inhibitor (MTI) agents have been related to the development of heart failure, myocardial ischemia, and conduction abnormalities. At present, there are no guidelines for patients undergoing MTI therapy as it pertains to both preventative and mitigatory strategies for cardiovascular complications. We conducted a literature review focusing on content related to the use of MTIs and their effect on the cardiovascular system. MTIs have been associated with various forms of cardiotoxicity, and fatal cardiotoxicities are rare. The most well-described cardiotoxicities are brady- and tachyarrhythmias. The co-administration of anthracycline-based agents with MTIs can increase the risk of cardiotoxicity.

Pathophysiological mechanisms of cardiotoxicity in chemotherapeutic agents

Certain success has been achieved in the treatment of cancer due to the development of various effective chemotherapeutic drugs. However, an increase in their effectiveness (aggressiveness) was associated with a growth of undesirable effects on the entire human body, in particular, on the cardiovascular system. The damage to the cardiovascular system from chemotherapy in many cases is more significant than from the underlying disease. In recent years, a new direction of medicine has been formed - cardio-oncology. The major groups of cardiotoxic chemotherapeutic agents are anthracyclines, inhibitors of epidermal growth factor receptor type 2 (anti-HER2), antimetabolites, microtubule inhibitors, proteasome inhibitors, platinum-based chemotherapeutic drugs, and angiogenesis inhibitors (inhibitors of vascular endothelial growth factor). This review discusses principal pathophysiological mechanisms of the cardiotoxicity of these chemotherapeutic drugs.

Molecular Mechanisms of Cardiomyocyte Death in Drug-Induced Cardiotoxicity

Homeostatic regulation of cardiomyocytes plays a crucial role in maintaining the normal physiological activity of cardiac tissue. Severe cardiotoxicity results in cardiac diseases including but not limited to arrhythmia, myocardial infarction and myocardial hypertrophy. Drug-induced cardiotoxicity limits or forbids further use of the implicated drugs. Such drugs that are currently available in the clinic include anti-tumor drugs (doxorubicin, cisplatin, trastuzumab, etc.), antidiabetic drugs (rosiglitazone and pioglitazone), and an antiviral drug (zidovudine). This review focused on cardiomyocyte death forms and related mechanisms underlying clinical drug-induced cardiotoxicity, including apoptosis, autophagy, necrosis, necroptosis, pryoptosis, and ferroptosis. The key proteins involved in cardiomyocyte death signaling were discussed and evaluated, aiming to provide a theoretical basis and target for the prevention and treatment of drug-induced cardiotoxicity in the clinical practice.

Human In Vitro Models for Assessing the Genomic Basis of Chemotherapy-Induced Cardiovascular Toxicity

Chemotherapy-induced cardiovascular toxicity (CICT) is a well-established risk for cancer survivors and causes diseases such as heart failure, arrhythmia, vascular dysfunction, and atherosclerosis. As our knowledge of the precise cardiovascular risks of each chemotherapy agent has improved, it has become clear that genomics is one of the most influential predictors of which patients will experience cardiovascular toxicity. Most recently, GWAS-led, top-down approaches have identified novel genetic variants and their related genes that are statistically related to CICT. Importantly, the advent of human-induced pluripotent stem cell (hiPSC) models provides a system to experimentally test the effect of these genomic findings in vitro, query the underlying mechanisms, and develop novel strategies to mitigate the cardiovascular toxicity liabilities due to these mechanisms. Here we review the cardiovascular toxicities of chemotherapy drugs, discuss how these can be modeled in vitro, and suggest how these models can be used to validate genetic variants that predispose patients to these effects.

Ponatinib-induced cardiotoxicity: delineating the signalling mechanisms and potential rescue strategies

AIMS

Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of chronic myelogenous leukaemia (CML). However, cardiotoxicity of these agents remains a serious concern. The underlying mechanism of these adverse cardiac effects is largely unknown. Delineation of the underlying mechanisms of TKIs associated cardiac dysfunction could guide potential prevention strategies, rescue approaches, and future drug design. This study aimed to determine the cardiotoxic potential of approved CML TKIs, define the associated signalling mechanism and identify potential alternatives.

METHODS AND RESULTS

In this study, we employed a zebrafish transgenic BNP reporter line that expresses luciferase under control of the nppb promoter (nppb:F-Luciferase) to assess the cardiotoxicity of all approved CML TKIs. Our in vivo screen identified ponatinib as the most cardiotoxic agent among the approved CML TKIs. Then using a combination of zebrafish and isolated neonatal rat cardiomyocytes, we delineated the signalling mechanism of ponatinib-induced cardiotoxicity by demonstrating that ponatinib inhibits cardiac prosurvival signalling pathways AKT and extra-cellular-signal-regulated kinase (ERK), and induces cardiomyocyte apoptosis. As a proof of concept, we augmented AKT and ERK signalling by administration of Neuregulin-1β (NRG-1β), and this prevented ponatinib-induced cardiomyocyte apoptosis. We also demonstrate that ponatinib-induced cardiotoxicity is not mediated by inhibition of fibroblast growth factor signalling, a well-known target of ponatinib. Finally, our comparative profiling for the cardiotoxic potential of CML approved TKIs, identified asciminib (ABL001) as a potentially much less cardiotoxic treatment option for CML patients with the T315I mutation.

CONCLUSION

Herein, we used a combination of in vivo and in vitro methods to systematically screen CML TKIs for cardiotoxicity, identify novel molecular mechanisms for TKI cardiotoxicity, and identify less cardiotoxic alternatives.

Mechanisms and potential interventions associated with the cardiotoxicity of ErbB2-targeted drugs: Insights from in vitro, in vivo, and clinical studies in breast cancer patients

Breast cancer is the most frequently occurring cancer among women worldwide. Human epidermal growth factor receptor 2 (HER2 or ErbB2) is overexpressed in between 20 and 25% of invasive breast cancers and is associated with poor prognosis. Trastuzumab, an anti-ErbB2 monoclonal antibody, reduces cancer recurrence and mortality in HER2-positive breast cancer patients, but unexpectedly induces cardiac dysfunction, especially when used in combination with anthracycline-based chemotherapy. Novel approved ErbB2-targeting drugs, including lapatinib, pertuzumab, and trastuzumab-emtansine, also potentially cause cardiotoxicity, although early clinical studies demonstrate their cardiac safety profile. Unfortunately, the mechanism involved in causing the cardiotoxicity is still not completely understood. In addition, the use of preventive interventions against trastuzumab-induced cardiac dysfunction, including angiotensin-converting enzyme inhibitors and beta-blockers, remain controversial. Thus, this review aims to summarize and discuss the evidence currently available from in vitro, in vivo, and clinical studies regarding the mechanism and potential interventions associated with the cardiotoxicity of ErbB2-targeted drugs.

Role of oxidative stress in cardiotoxicity of antineoplastic drugs

Tumors and heart disease are two of the leading causes of human death. With the development of anti-cancer therapy, the survival rate of cancer patients has been significantly improved. But at the same time, the incidence of cardiovascular adverse events caused by cancer treatment has also been considerably increased, such as arrhythmia, left ventricular (LV) systolic and diastolic dysfunction, and even heart failure (HF), etc., which seriously affects the quality of life of cancer patients. More importantly, the occurrence of adverse events may lead to the adjustment or the cessation of anti-cancer treatment, which affects the survival rate of patients. Understanding the mechanism of cardiotoxicity (CTX) induced by antineoplastic drugs is the basis of adequate protection of the heart without impairing the efficacy of antineoplastic therapy. Based on current research, a large amount of evidence has shown that oxidative stress (OS) plays an essential role in CTX induced by antineoplastic drugs and participates in its toxic reaction directly and indirectly. Here, we will review the mechanism of action of OS in cardiac toxicity of antineoplastic drugs, to provide new ideas for researchers, and provide further guidance for clinical prevention and treatment of cardiac toxicity of anti-tumor drugs in the future.

Pharmacogenetics of Chemotherapy-Induced Cardiotoxicity

PURPOSE OF REVIEW

The goal of this review is to summarize current understanding of pharmacogenetics and pharmacogenomics in chemotherapy-induced cardiotoxicity.

RECENT FINDINGS

Most of the studies rely on in vitro cytotoxic assays. There have been several smaller scale candidate gene approaches and a handful of genome-wide studies linking genetic variation to susceptibility to chemotherapy-induced cardiotoxicity. Currently, pharmacogenomic testing of all childhood cancer patients with an indication for doxorubicin or daunorubicin therapy for RARG rs2229774, SLC28A3 rs7853758, and UGT1A6*4 rs17863783 variants is recommended. There is no recommendation regarding testing in adults. There is clear evidence pointing to the role of pharmacogenetics and pharmacogenomics in cardiotoxicity susceptibility to chemotherapeutic agents. Larger scale studies are needed to further identify susceptibility markers and to develop pharmacogenomics-based risk profiling to improve quality of life and life expectancy in cancer survivors.

Characterization of cytoskeleton features and maturation status of cultured human iPSC-derived cardiomyocytes

Recent innovations in stem cell technologies and the availability of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have opened new possibilities for studies and drug testing on human cardiomyocytes in vitro. Still, there are concerns about the precise nature of such 'reprogrammed' cells. We have performed an investigation using immunocytochemistry and confocal microscopy on several cellular features using commercially available hiPSC-CMs. For some selected developmentally regulated or cardiac chamber-specific proteins, we have compared the results from hiPSC-derived cardiomyocytes with freshly isolated, ventricular cardiomyocytes from adult rats. The results show that all typical cardiac proteins are expressed in these hiPSC-CMs. Furthermore, intercalated disc-like structures, calcium cycling proteins, and myofibrils are present. However, some of these proteins are only known from early developmental stages of the ventricular myocardium or the diseased adult heart. A heterogeneous expression pattern in the cell population was noted for some muscle proteins, such as for myosin light chains, or incomplete organization in sarcomeres, such as for telethonin. These observations indicate that hiPSC-CMs can be considered genuine human cardiomyocytes of an early developmental state. The here described marker proteins of maturation may become instrumental in future studies attempting the improvement of cardiomyocyte in vitro models.

Trastuzumab cardiotoxicity: from clinical trials to experimental studies

Epidermal growth factor receptor-2 (HER-2) is overexpressed in 20 to 25% of human breast cancers, which is associated with aggressive tumour growth and poor prognosis. Trastuzumab (Herceptin®) is a humanized monoclonal antibody directed against HER-2, the first highly selective form of therapy targeting HER-2 overexpressing tumours. Although initial trials indicated high efficacy and a favourable safety profile of the drug, the first large, randomized trial prompted a retrospective analysis of cardiac dysfunction in earlier trials utilizing trastuzumab. There has been ongoing debate on the cardiac safety of trastuzumab ever since, initiating numerous clinical and preclinical investigations to better understand the background of trastuzumab cardiotoxicity and evaluate its effects on patient morbidity. Here, we have given a comprehensive overview of our current knowledge on the cardiotoxicity of trastuzumab, primarily focusing on data from clinical trials and highlighting the main molecular mechanisms proposed.

LINKED ARTICLES

This article is part of a themed section on New Insights into Cardiotoxicity Caused by Chemotherapeutic Agents. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.21/issuetoc.

The impact of paclitaxel and carboplatin chemotherapy on the autonomous nervous system of patients with ovarian cancer

Background

Paclitaxel-based regimens are frequently associated with the development of peripheral neuropathy. The autonomous nervous system (ANS) effects, however, of this chemotherapeutic agent remain unexplored.

Methods

We investigated a group of 31 female patients with ovarian cancer receiving treatment with paclitaxel and carboplatin, as well as a group of 16 healthy age- and gender-matched healthy volunteers. All study participants completed a questionnaire and were assessed neurophysiologically at three time points (baseline, 3–4 months and 6–8 months following the onset of chemotherapy). The evaluation of the ANS included assessment of the adrenergic cardiovascular function (orthostatic hypotension-OH), parasympathetic heart innervation (30/15 ratio) and sympathetic skin response (SSR).

Results

At the 3–4 months ANS assessment, 19.2 % of the patients had systolic OH and the same percentage had diastolic OH, but at the 6–8 months evaluation no patient had systolic OH and only 13.8 % had diastolic OH. The values of the 30/15 ratio were significantly reduced at both time points, whereas the SSR was not affected.

Conclusions

Combined paclitaxel and carboplatin chemotherapy is associated with significant effects on the parasympathetic heart innervation and occasionally with effects on the adrenergic cardiovascular reaction. The SSR remained unaffected. Physicians should be alert to the possibility of these treatment-emergent side effects, so as to monitor ANS parameters and introduce treatment modifications accordingly. Our findings however, should be validated in larger cohorts.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-016-0710-4) contains supplementary material, which is available to authorized users.

Cardio-Oncology: An Update on Cardiotoxicity of Cancer-Related Treatment

Through the success of basic and disease-specific research, cancer survivors are one of the largest growing subsets of individuals accessing the healthcare system. Interestingly, cardiovascular disease is the second leading cause of morbidity and mortality in cancer survivors after recurrent malignancy. This recognition has helped stimulate a collaboration between oncology and cardiology practitioners and researchers, and the portmanteau cardio-oncology (also known as onco-cardiology) can now be found in many medical centers. This collaboration promises new insights into how cancer therapies impact cardiovascular homeostasis and long-term effects on cancer survivors. In this review, we will discuss the most recent views on the cardiotoxicity related to various classes of chemotherapy agents and radiation. We will also discuss broadly the current strategies for treating and preventing cardiovascular effects of cancer therapy.

Neuregulin-1β promotes glucose uptake via PI3K/Akt in neonatal rat cardiomyocytes

Nrg1β is critically involved in cardiac development and also maintains function of the adult heart. Studies conducted in animal models showed that it improves cardiac performance under a range of pathological conditions, which led to its introduction in clinical trials to treat heart failure. Recent work also implicated Nrg1β in the regenerative potential of neonatal and adult hearts. The molecular mechanisms whereby Nrg1β acts in cardiac cells are still poorly understood. In the present study, we analyzed the effects of Nrg1β on glucose uptake in neonatal rat ventricular myocytes and investigated to what extent mTOR/Akt signaling pathways are implicated. We show that Nrg1β enhances glucose uptake in cardiomyocytes as efficiently as IGF-I and insulin. Nrg1β causes phosphorylation of ErbB2 and ErbB4 and rapidly induces the phosphorylation of FAK (Tyr(861)), Akt (Thr(308) and Ser(473)), and its effector AS160 (Thr(642)). Knockdown of ErbB2 or ErbB4 reduces Akt phosphorylation and blocks the glucose uptake. The Akt inhibitor VIII and the PI3K inhibitors LY-294002 and Byl-719 abolish Nrg1β-induced phosphorylation and glucose uptake. Finally, specific mTORC2 inactivation after knockdown of rictor blocks the Nrg1β-induced increases in Akt-p-Ser(473) but does not modify AS160-p-Thr(642) or the glucose uptake responses to Nrg1β. In conclusion, our study demonstrates that Nrg1β enhances glucose uptake in cardiomyocytes via ErbB2/ErbB4 heterodimers, PI3Kα, and Akt. Furthermore, although Nrg1β activates mTORC2, the resulting Akt-Ser(473) phosphorylation is not essential for glucose uptake induction. These new insights into pathways whereby Nrg1β regulates glucose uptake in cardiomyocytes may contribute to the understanding of its regenerative capacity and protective function in heart failure.

Progress in neuregulin/ErbB signaling and chronic heart failure

Heart failure is one of the leading causes of death today. It is a complex clinical syndrome in which the heart has a reduced contraction ability and decreased viable myocytes. Novel approaches to the clinical management of heart failure have been achieved through an understanding of the molecular pathways necessary for normal heart development. Neuregulin-1 (NRG-1) has emerged as a potential therapeutic target based on the fact that mice null for NRG-1 or receptors mediating its activity, ErbB2 and ErbB4, are embryonic lethal and exhibit severe cardiac defects. Preclinical studies performed with animal models of heart failure demonstrate that treatment with NRG-1 significantly improves heart function and survival. Clinical data further support NRG-1 as a promising drug candidate for the treatment of cardiac dysfunction in patients. Recent studies have revealed the mechanism underlying the therapeutic effects of NRG-1/ErbB signaling in the treatment of heart failure. Through activation of upstream signaling molecules such as phosphoinositide 3-kinase, mitogen-activated protein kinase, and focal adhesion kinase, NRG-1/ErbB pathway activation results in increased cMLCK expression and enhanced intracellular calcium cycling. The former is a regulator of the contractile machinery, and the latter triggers cell contraction and relaxation. In addition, NRG-1/ErbB signaling also influences energy metabolism and induces epigenetic modification in cardiac myocytes in a way that more closely resembles healthy heart. These observations reveal potentially new treatment options for heart failure.

Anthracyclines/trastuzumab: new aspects of cardiotoxicity and molecular mechanisms

Anticancer drugs continue to cause significant reductions in left ventricular ejection fraction resulting in congestive heart failure. The best-known cardiotoxic agents are anthracyclines (ANTHs) such as doxorubicin (DOX). For several decades cardiotoxicity was almost exclusively associated with ANTHs, for which cumulative dose-related cardiac damage was the use-limiting step. Human epidermal growth factor (EGF) receptor 2 (HER2; ErbB2) has been identified as an important target for breast cancer. Trastuzumab (TRZ), a humanized anti-HER2 monoclonal antibody, is currently recommended as first-line treatment for patients with metastatic HER2(+) tumors. The use of TRZ may be limited by the development of drug intolerance, such as cardiac dysfunction. Cardiotoxicity has been attributed to free-iron-based, radical-induced oxidative stress. Many approaches have been promoted to minimize these serious side effects, but they are still clinically problematic. A new approach to personalized medicine for cancer that involves molecular screening for clinically relevant genomic alterations and genotype-targeted treatments is emerging.

Breast cancer therapy and cardiovascular risk: focus on trastuzumab

Breast cancer is the most common cancer in the UK. Advances in the methods of early diagnosis as well as newer and more effective treatments have led to improvements of disease-free and overall survival over the last decade. Almost one-third of breast cancers present with an aggressive form characterized by increased expression of human epidermal growth receptor 2 (HER2) proteins. A targeted treatment using monoclonal antibodies against HER2 expression such as trastuzumab has been shown to improve survival. Unfortunately, there is a degree of cardiotoxicity associated with these agents, as inhibition of HER2 pathways can also impair cardioprotective pathways. In the present review, we discuss the mechanisms by which trastuzumab might affect vascular homeostasis leading to endothelial dysfunction. We also provide suggestions for future research examining the effects of trastuzumab on the vasculature in breast cancer.

Neuregulin as a heart failure therapy and mediator of reverse remodeling

The beta isoform of Neuregulin-1 (NRG-1β), along with its receptors (ErbB2-4), is required for cardiac development. NRG-1β, as well as the ErbB2 and ErbB4 receptors, is also essential for maintenance of adult heart function. These observations have led to its evaluation as a therapeutic for heart failure. Animal studies and ongoing clinical trials have demonstrated beneficial effects of two forms of recombinant NRG-1β on cardiac function. In addition to the possible role for recombinant NRG-1βs as heart failure therapies, endogenous NRG-1β/ErbB signaling appears to play a role in restoring cardiac function after injury. The potential mechanisms by which NRG-1β may act as both a therapy and a mediator of reverse remodeling remain incompletely understood. In addition to direct effects on cardiac myocytes NRG-1β acts on the vasculature, interstitium, cardiac fibroblasts, and hematopoietic and immune cells, which, collectively, may contribute to NRG-1β's role in maintaining cardiac structure and function, as well as mediating reverse remodeling.

The role of antioxidants in the era of cardio‑oncology

Although most chemotherapeutic drugs have the potential to exert cardiotoxicity, these drugs have been chosen for use in cancer treatment because survival and curability benefits outweigh the risk of these complications. Anthracyclines, for example, are a powerful class of chemotherapeutic agents; however, their use is restricted by dose-related cardiotoxicity. Experimental evidence strongly supports the role of reactive oxygen species in this process, suggesting that antioxidants may be effective in protecting the heart from toxicity. Clinical use of antioxidants to protect the heart during anthracycline chemotherapy has been controversial due to the potential for reduced cytotoxic efficacy toward cancer cells. Results from randomized clinical trials addressing whether antioxidants either reduce the incidence of clinical heart failure among patients undergoing anthracycline-based chemotherapy or reduce the response rates to anthracycline-based chemotherapy have been unclear. While anthracyclines are by far the most well-studied antitumor agents with cardiotoxic properties, evidence now shows that reactive oxygen species may play roles in cardiotoxicity induced by other chemotherapeutic agents such as cyclophosphamide, cisplatin, 5-fluorouracil, and trastuzumab. Thus, in the new era of combination therapy and long-term survival of cancer patients, the use of antioxidants to support cancer therapy should be revisited.

Trastuzumab alters the expression of genes essential for cardiac function and induces ultrastructural changes of cardiomyocytes in mice

Treatment with trastuzumab, a humanized monoclonal antibody directed against the extracellular domain of Human Epidermal Growth Factor Receptor 2 (HER2), very successfully improves outcomes for women with HER2-positive breast cancer. However, trastuzumab treatment was recently linked to potentially irreversible serious cardiotoxicity, the mechanisms of which are largely elusive. This study reports that trastuzumab significantly alters the expression of myocardial genes essential for DNA repair, cardiac and mitochondrial functions, which is associated with impaired left ventricular performance in mice coupled with significant ultrastructural alterations in cardiomyocytes revealed by electron microscopy. Furthermore, trastuzumab treatment also promotes oxidative stress and apoptosis in myocardium of mice, and elevates serum levels of cardiac troponin-I (cTnI) and cardiac myosin light chain-1 (cMLC1). The elevated serum levels of cMLC1 in mice treated with trastuzumab highlights the potential that cMLC1 could be a useful biomarker for trastuzumab-induced cardiotoxicity.

Gene transfer of human neuregulin-1 attenuates ventricular remodeling in diabetic cardiomyopathy rats

Neuregulin-1 (NRG-1) is a cardioactive growth factor released from endothelial cells. However, the effect of NRG-1 on ventricular remodeling in diabetic cardiomyopathy (DCM) remains unclear. The aim of the present study was to investigate the pathophysiological role of NRG-1 in a rat model of DCM. Rat cardiac microvascular endothelial cells (CMECs) were transfected with human NRG-1 (hNRG-1) lentivirus. The hNRG-1 medium was utilized to culture rat cardiomyocytes. The cardiomyocytes were counted with a hemacytometer to determine the proliferation index and Annexin V/propidium iodide double staining was employed to examine the apoptotic rate. A rat model of DCM was induced by an intraperitoneal injection of streptozotocin. The hNRG-1 lentivirus was injected into the myocardium of the DCM model rats. Four weeks after the lentiviral injection, cardiac catheterization was performed to evaluate the cardiac function. Apoptotic cells were determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. Left ventricular sections were stained with Masson’s trichrome to investigate the myocardial collagen content. The expression levels of related genes and proteins were analyzed. The results indicated that hNRG-1 conditioned medium stimulated the proliferation and counteracted the apoptosis of cardiomyocytes in vitro. In the rats with DCM, gene transfer of hNRG-1 to the myocardium improved heart function, as indicated by invasive hemodynamic measurements. In addition, hNRG-1 reduced the number of apoptotic cells, decreased the expression of bax and increased the expression of bcl-2 in the myocardium of the DCM model rats. Myocardial fibrosis and type I and III pro-collagen mRNA levels in the myocardium were significantly reduced by hNRG-1. hNRG-1 also increased the expression of phospho-Akt and phospho-eNOS in the myocardium. In conclusion, the gene transfer of hNRG-1 ameliorates cardiac dysfunction in diabetes. Although further studies are required, NRG-1 appears to protect cardiomyocytes against apoptosis and to reduce the extent of myocardial interstitial fibrosis.

Neuregulin-1 protects against doxorubicin-induced apoptosis in cardiomyocytes through an Akt-dependent pathway

In previous studies, it has been shown that recombinant human neuregulin-1(rhNRG-1) is capable of improving the survival rate in animal models of doxorubicin (DOX)-induced cardiomyopathy; however, the underlying mechanism of this phenomenon remains unknown. In this study, the role of rhNRG-1 in attenuating doxorubicin-induce apoptosis is confirmed. Neonatal rat ventricular myocytes (NRVMs) were subjected to various treatments, in order to both induce apoptosis and determine the effects of rhNRG-1 on the process. Activation of apoptosis was determined by observing increases in the protein levels of classic apoptosis markers (including cleaved caspase-3, cytochrome c, Bcl-2, BAX and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining). The activation of Akt was detected by means of western blot analysis. The study results showed that doxorubicin increased the number of TUNEL positive cells, as well as the protein levels of cleaved caspase-3 and cytochrome c, and reduced the ratio of Bcl-2/Bax. However, all of these effects were markedly antagonized by pretreament with rhNRG-1. It was then further demonstrated that the effects of rhNRG-1 could be blocked by the phosphoinositole-3-kinase inhibitor LY294002, indicating the involvement of the Akt process in mediating the process. RhNRG-1 is a potent inhibitor of doxorubicin-induced apoptosis, which acts through the PI3K-Akt pathway. RhNRG-1 is a novel therapeutic drug which may be effective in preventing further damage from occurring in DOX-induced damaged myocardium.

Neuregulin-1/ErbB signaling is impaired in the rat model of diabetic cardiomyopathy

BACKGROUND

Diabetic cardiomyopathy (DCP) is one of the leading causes of increased morbidity and mortality in the diabetic population. The neuregulin-1(NRG1)/ErbB signal system plays a critical role in maintenance of adult heart function. But little is known about the changes of NRG1/ErbB signal system in DCP. The aim of this study was to investigate the changes of the NRG1/ErbB signal system in DCP.

METHODS

A rat model of DCP was established using a single intraperitoneal injection of streptozotocin (STZ). Cardiac function was assessed using echocardiography. The left ventricle fibrosis was evaluated using Masson's trichrome staining. The mRNA expression profiles of ErbB2 and ErbB4 receptors were evaluated using real-time polymerase chain reaction. The protein expression of NRG1 and the phosphorylation of ErbB2 and ErbB4 receptors were assessed using Western blot analysis.

RESULTS

The results showed dramatic left ventricle fibrosis and impaired left ventricle systolic function at 12 weeks after STZ-induced diabetes. This study also showed that ErbB2 and ErbB4 mRNA expression and NRG1 protein expression in the left ventricular myocardium were significantly decreased. In addition, we observed decreased phosphorylation of the ErbB2 and ErbB4 receptors at 12 weeks after the induction of diabetes.

CONCLUSIONS

These findings suggest that NRG1/ErbB signaling is impaired in DCP, which may play some roles in the pathogenesis of DCP.

Cardio-oncology in targeting the HER receptor family: the puzzle of different cardiotoxicities of HER2 inhibitors

The HER family of tyrosine kinase receptors includes several members that are clinically important targets in cancer therapies, in particular HER1 (the EGF receptor) and HER2, other members include HER3 and HER4. Trastuzumab, a humanized monoclonal antibody and lapatinib, a tyrosine kinase inhibitor, are drugs that target HER2, which is highly expressed in 20-30% of breast cancers. Trastuzumab is recommended as an adjuvant therapy for lymph node positive, HER2-positive breast cancers, or node-negative cancer with high-risk of recurrence, as well as in stage IV cancers. One serious side effect of trastuzumab is cardiomyocyte dysfunction, resulting in reduced heart contractile efficiency. The incidence of collateral effects on the heart with trastuzumab therapy increases in people with cardiovascular risk factors, heart disease and when combined with other chemotherapeutics. When cardiotoxicity was observed with trastuzumab, several studies have addressed potential cardiac damage of trastuzumab itself and lapatinib. The differences in cardiovascular effects of these two compounds are somewhat unexpected and suggest distinct mechanisms of action, which have clear implications in clinical application and prevention of cardiotoxicity in cardio-oncological approaches.

Herceptin, a recombinant humanized anti-ERBB2 monoclonal antibody, induces cardiomyocyte death

P53 protein levels are elevated by trastuzumab and the biologically similar rat ERBB2/HER2/NEU antibody; and that this coincides with enhanced apoptosis, increased cleaved caspase-3 levels and diminished cardiac function. We also demonstrate that MDM2 may be a regulatory target of anti-ERBB2 thereby implicating the MDM2/p53 axis as a potential molecular component for the undesirable cardiac outcomes noted with trastuzumab. Finally, we show that these MDM2/p53-mediated events are independent of both the ERK1/2 and Akt systems. In conclusion, our findings suggest that the adverse cardiac events observed with trastuzumab may stem from its negative regulation of MDM2 events which impairs p53 degradation resultantly promoting apoptosis leading to cardiac dysfunction. These observations may have important therapeutic implications since they suggest that anticancer agents that inhibit MDM2 and its downstream actions may curb tumor progression at the expense of increasing cardiac stress.

Inhibition of ErbB2 by herceptin reduces viability and survival, induces apoptosis and oxidative stress in Calu-3 cell line

Human epidermal growth factor receptor 2 (ErbB2) amplification and overexpression has been seen in many cancer types including non-small cell lung cancer (NSCLC). Thus, ErbB2 is an important target for cancer therapies. Increased ErbB2 expression has been associated with drug resistance in cancer cells. Herceptin is a humanized monoclonal antibody that targets the extracellular domain of ErbB2. In this study, we aimed to block ErbB2 signaling with Herceptin and assess cytotoxicity and effects on apoptosis, oxidative stress, nuclear factor kappa-B (NF-kB), and Survivin expression in Calu-3 cell line. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay were used to assess cell viability as a marker of proliferation. Acridine orange/ethidium bromide (AO/EB) staining and caspase 3/7 activity were measured as the markers of apoptosis. The relative expressions of NF-kB-p50 and Survivin mRNAs were evaluated. Activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT), and the levels of glutathione (GSH) and reactive oxygen species (ROS) were determined in a time- and dose-dependent manner. Our results show that Herceptin treatment inhibits cell proliferation and activates apoptosis but without effects on Survivin and NF-kB expression in Calu-3 cell line. Intracellular glutathione levels and SOD and CAT activities were decreased in a time- and dose-dependent manner associated with oxidative stress. Also, ROS were increased at 24 h. These results provide evidence that Herceptin can be used as a cytotoxic and apoptotic agent in NSCLC.

Neuregulin-1beta1 rapidly modulates nitric oxide synthesis and calcium handling in rat cardiomyocytes

AIMS

The ErbB-neuregulin-1β1 (Nrg1β1) pathway is required for cardiac development and exerts chronic effects on the postnatal adult heart. Long-term application of Nrg1β1 results in hypertrophy and protection against oxidative stress and cytotoxic agents. We performed experiments with acute Nrg1β1 treatment to find evidence for a further protective role due to rapid modulation of adult cardiomyocyte function.

METHODS AND RESULTS

In confocal fluorimetric measurements, Nrg1β1 induced a calcium-independent increase in nitric oxide (NO) production in isolated adult rat ventricular myocytes (ARVCMs) that was blocked by the phosphoinositide-3-kinase (PI3K) inhibitor Wortmannin. Western blot analysis showed enhancement of endothelial nitric oxide synthase phosphorylation in Nrg1β1-treated ARVCMs, which was attenuated by Wortmannin. Nrg1β1 induced a significant increase in calcium transient amplitude (indo-1 ratiometric measurement) and accelerated the recovery of cytosolic calcium in the sarcoplasmic reticulum without affecting whole-cell L-type calcium current. Wortmannin or the protein kinase G inhibiting peptide (DT-2) abolished the increase in calcium transient amplitude and the acceleration of calcium recovery induced by Nrg1β1 treatment. Immunofluorescence analysis revealed that Nrg1β1 treatment increased phospholamban phosphorylation, and the effect was blocked by PI3K and protein kinase G inhibition. Caffeine-releasable sarcoplasmic reticulum calcium content was also higher during Nrg1β1 administration.

CONCLUSION

Rapid activation of PI3K, endothelial nitric oxide synthase and protein kinase G and a consequent improvement in diastolic calcium can be added to established Nrg1 protective roles.

A Phase II, randomized, double-blind, multicenter, based on standard therapy, placebo-controlled study of the efficacy and safety of recombinant human neuregulin-1 in patients with chronic heart failure

OBJECTIVES

The purpose of this study was to assess the safety and efficacy of recombinant human neuregulin-1 (rhNRG-1) in chronic heart failure (CHF) patients.

BACKGROUND

Neuregulin-1 plays important roles in maintaining cardiomyocyte structure and cardiac pumping functionality and physiology. Previously, rhNRG-1 was proven to be effective in treating heart failure in animals by reducing end-diastolic volume (EDV) and end-systolic volume (ESV) and increasing left ventricular ejection fraction (LVEF%).

METHODS

A total of 44 CHF patients designated as New York Heart Association functional class II or III were enrolled in a double-blind, randomized manner and treated with a placebo or rhNRG-1 (0.3, 0.6, or 1.2 microg/kg/day) for 10 days, in addition to standard therapies. The follow-up period was 90 days; left ventricular function and structure measured by magnetic resonance imaging were the primary end points.

RESULTS

Although not statistically different from placebo, the LVEF% was significantly increased by 27.11 +/- 31.12% (p = 0.009) at day 30 after rhNRG-1 treatment in the 0.6-microg/kg group, whereas it was only increased 5.83 +/- 25.75% in the placebo group (p = 0.49). In addition, there were decreases in ESV (-11.58 +/- 12.74%, p = 0.002) and EDV (-5.64 +/- 10.03%, p = 0.05) in the 0.6-microg/kg/day group at day 30; more importantly, both ESV and EDV levels continued to decrease at day 90 (-20.79 +/- 17.03% and -14.03 +/- 13.17%, respectively), accompanied by a sustained increase in LVEF%. This suggests that short-term treatment with rhNRG-1 results in a long-term reversal of remodeling. The effective dose was proven to be tolerable and safe for CHF patients.

CONCLUSIONS

rhNRG-1 improved the cardiac function of CHF patients by increasing the LVEF% and showed the capability of antiremodeling by decreasing ESV and EDV compared with pre-treatment. (A Randomized, Double-Blind, Multi-Center, Placebo Parallel controlled, Standard Therapy Based Phase II Clinical Trial to Evaluate the Efficacy and Safety of Recombinant Human Neuregulin-1 for Injection in Patients with Chronic Heart Failure; ChiCTR-TRC-00000414).

The vulnerability of the heart as a pluricellular paracrine organ: lessons from unexpected triggers of heart failure in targeted ErbB2 anticancer therapy

In this review, we address clinical aspects and mechanisms of ventricular dysfunction induced by anticancer drugs targeted to the ErbB2 receptor. ErbB2 antagonists prolong survival in cancer, but also interfere with homeostatic processes in the heart. ErbB2 is a coreceptor for ErbB4, which is activated by neuregulin-1. This epidermal growth factor-like growth factor is released from endothelial cells in the endocardium and in the myocardial microcirculation, hence contributing to intercellular crosstalk in the ventricle. We look at the physiological aspects of neuregulin-1/ErbB signaling in the ventricle, and review its (mal)adaptive responses in chronic heart failure. We also compare structural aspects of ErbB receptor activation in cancer and cardiac cells, and analyze the mode of action of current ErbB2 antagonists. This allows us to predict how these drugs interfere with paracrine processes in the ventricle. Differences in the mode of action of individual ErbB2 antagonists affect their impact on the function of the ventricle, considered to be "on-target" or "off-target." Establishing the relation between the cardiac side effects of ErbB2 antagonists and their impact on paracrine ventricular control mechanisms may direct the design of a next generation of ErbB2 inhibitors. For cardiologists, there are lessons to be learned from the unexpected side effects of ErbB2-targeted cancer therapy. The vulnerability of the heart as a pluricellular paracrine system appears greater than anticipated and intercellular crosstalk an essential component of its functional and structural integrity.

The role of cell death and myofibrillar damage in contractile dysfunction of long-term cultured adult cardiomyocytes exposed to doxorubicin

In failing hearts cardiomyocytes undergo alterations in cytoskeleton structure, contractility and viability. It is not known presently, how stress-induced changes of myofibrils correlate with markers for cell death and contractile function in cardiomyocytes. Therefore, we have studied the progression of contractile dysfunction, myofibrillar damage and cell death in cultured adult cardiomyocytes exposed to the cancer therapy doxorubicin. We demonstrate, that long-term cultured adult cardiomyocytes, a well-established model for the study of myofibrillar structure and effects of growth factors, can also be used to assess contractility and calcium handling. Adult rat ventricular myocytes (ARVM) were isolated and cultured for a total of 14 days in serum containing medium. The organization of calcium-handling proteins and myofibrillar structure in freshly isolated and in long-term cultured adult cardiomyocytes was studied by immunofluorescence and electron microscopy. Excitation contraction-coupling was analyzed by fura 2 and video edge detection in electrically paced cardiomyocytes forming a monolayer, and cell death and viability was measured by TUNEL assay, LDH release, MTT assay, and Western blot for LC3. Adult cardiomyocytes treated with Doxo showed apoptosis and necrosis only at supraclinical concentrations. Treated cells displayed merely alterations in cytoskeleton organization and integrity concomitant with contractile dysfunction and up-regulation of autophagosome formation, but no change in total sarcomeric protein content. We propose, that myofibrillar damage contributes to contractile dysfunction prior to cell death in adult cardiomyocytes exposed to clinically relevant concentrations of anthracyclines.