Potential protective role of angiotensin-converting enzyme inhibitors captopril and enalapril against adriamycin-induced acute cardiac and hepatic toxicity in rats

Early detection of anthracycline-induced cardiotoxicity using [68 Ga]Ga-FAPI-04 imaging

PURPOSE

Anthracycline-induced cardiotoxicity (AIC), whose major manifestation is diffuse myocardial fibrosis, is an important clinical problem in cancer therapy. Therefore, early identification and treatment are clinically important. This study aims to explore the feasibility of using 68 Ga-labelled fibroblast activation protein (FAP) inhibitor ([68 Ga]Ga-FAPI) positron emission tomography/computed tomography (PET/CT) for the early identification of the fibrotic process and guidance of antifibrosis therapy in AIC.

METHODS

An AIC rat model was induced by the intravascular administration of doxorubicin (DOX) once per week for 1, 2, 3 and 6 weeks (2.5 mg/kg/injection, groups 1-4), whereas intravascular saline was administered to control rats. Experimental and control groups (n = 4) underwent [68 Ga]Ga-FAPI PET/CT following disease induction. Groups 5 and 6 received DOX injections for 3 and 6 weeks, treated with angiotensin-converting enzyme (ACE) inhibitor starting at 3 weeks, treated with enalapril (20 mg/kg, gastric gavage) daily and underwent echocardiography and [68 Ga]Ga-FAPI PET/CT at 3 weeks after treatment. Rat hearts were subjected to haematoxylin and eosin staining, FAP immunohistochemistry, Sirius red staining and Masson's trichrome staining to investigate the pathological changes and deposition of collagen fibres. Rat blood was sampled weekly for the enzyme-linked immunosorbent assay of various markers of myocardial injury, such as plasma cardiac troponin I, B-type natriuretic peptide and angiotensin II.

RESULTS

[68 Ga]Ga-FAPI-04 uptake by the heart was significantly higher in the cardiotoxicity group than in the control group at weeks 3 (SUVmax: 1.21 ± 0.23 vs 0.67 ± 0.01, P < 0.05) and 6 (SUVmax: 1.48 ± 0.28 vs 0.67 ± 0.08, P < 0.001), whereas left ventricle ejection fraction (LVEF) did not significantly differ between normal and AIC rats at week 3. FAP+ expression began to increase starting at week 3, before irreversible fibrotic changes were detected, until week 6. After 3 weeks of enalapril treatment, [68 Ga]Ga-FAPI-04 accumulation decreased in groups 5 and 6 (SUVmax decreased from 1.21 ± 0.23 to 0.77 ± 0.08 and 1.48 ± 0.28 to 1.09 ± 1.06, P < 0.05). Cardiac function was preserved (LVEF was 75.7% ± 7.38% in group 3 vs 74.5% ± 2.45% in group 5, P > 0.05) and improved (LVEF increased from 51.6% ± 9.03% in group 4 to 65.2% ± 4.27% in group 6, P < 0.05), and myocardial fibrosis attenuated (from 6.5% ± 1.2% in group 4 to 4.31% ± 0.37% in group 6, P < 0.01).

CONCLUSION

[68 Ga]Ga-FAPI PET/CT can be used for the early detection of active myocardial fibrosis in AIC and the evaluation of the efficacy of therapeutic interventions. Early treatment guided by [68 Ga]Ga-FAPI PET/CT may reduce anthracycline-induced myocardial injury and improve heart function.

An update of the molecular mechanisms underlying anthracycline induced cardiotoxicity

Anthracycline drugs mainly include doxorubicin, epirubicin, pirarubicin, and aclamycin, which are widely used to treat a variety of malignant tumors, such as breast cancer, gastrointestinal tumors, lymphoma, etc. With the accumulation of anthracycline drugs in the body, they can induce serious heart damage, limiting their clinical application. The mechanism by which anthracycline drugs cause cardiotoxicity is not yet clear. This review provides an overview of the different types of cardiac damage induced by anthracycline-class drugs and delves into the molecular mechanisms behind these injuries. Cardiac damage primarily involves alterations in myocardial cell function and pathological cell death, encompassing mitochondrial dysfunction, topoisomerase inhibition, disruptions in iron ion metabolism, myofibril degradation, and oxidative stress. Mechanisms of uptake and transport in anthracycline-induced cardiotoxicity are emphasized, as well as the role and breakthroughs of iPSC in cardiotoxicity studies. Selected novel cardioprotective therapies and mechanisms are updated. Mechanisms and protective strategies associated with anthracycline cardiotoxicity in animal experiments are examined, and the definition of drug damage in humans and animal models is discussed. Understanding these molecular mechanisms is of paramount importance in mitigating anthracycline-induced cardiac toxicity and guiding the development of safer approaches in cancer treatment.

Doxorubicin-induced cardiotoxicity and risk factors

Doxorubicin (DOX) is an anthracycline antibiotic widely used as a chemotherapeutic agent to treat solid tumours and hematologic malignancies. Although useful in the treatment of cancers, the benefit of DOX is limited due to its cardiotoxic effect that is observed in a large number of patients. In the literature, there is evidence that the presence of various factors may increase the risk of developing DOX-induced cardiotoxicity. A better understanding of the role of these different factors in DOX-induced cardiotoxicity may facilitate the choice of the therapeutic approach in cancer patients suffering from various cardiovascular risk factors. In this review, we therefore discuss the latest findings in both preclinical and clinical research suggesting a link between DOX-induced cardiotoxicity and various risk factors including sex, age, ethnicity, diabetes, dyslipidaemia, obesity, hypertension, cardiovascular disease and co-medications.

Cardio-Oncology: Mechanisms, Drug Combinations, and Reverse Cardio-Oncology

Chemotherapy, radiotherapy, targeted therapy, and immunotherapy have brought hope to cancer patients. With the prolongation of survival of cancer patients and increased clinical experience, cancer-therapy-induced cardiovascular toxicity has attracted attention. The adverse effects of cancer therapy that can lead to life-threatening or induce long-term morbidity require rational approaches to prevention and treatment, which requires deeper understanding of the molecular biology underpinning the disease. In addition to the drugs used widely for cardio-protection, traditional Chinese medicine (TCM) formulations are also efficacious and can be expected to achieve “personalized treatment” from multiple perspectives. Moreover, the increased prevalence of cancer in patients with cardiovascular disease has spurred the development of “reverse cardio-oncology”, which underscores the urgency of collaboration between cardiologists and oncologists. This review summarizes the mechanisms by which cancer therapy induces cardiovascular toxicity, the combination of antineoplastic and cardioprotective drugs, and recent advances in reverse cardio-oncology.

Rutin and Quercetin Counter Doxorubicin-Induced Liver Toxicity in Wistar Rats via Their Modulatory Effects on Inflammation, Oxidative Stress, Apoptosis, and Nrf2

The presented study was performed to verify whether rutin and/or quercetin can inhibit liver injury induced by doxorubicin (DXR) in male Wistar rats. In this study, male Wistar rats were treated via the oral route with rutin and quercetin (50 mg/kg) either alone or in combination every other day for five weeks concomitant with receiving intraperitoneal DXR (2 mg/kg) two times a week for five successive weeks. Quercetin, rutin, and their combination significantly improved the deteriorated serum AST, ALT, and ALP activities and total bilirubin level, as well as albumin, AFP, and CA 19.9 levels in DXR-injected rats. Treatments of the DXR-injected group with quercetin and rutin prevented the elevation in liver lipid peroxidation and the reduction in superoxide dismutase, glutathione-S-transferase and glutathione peroxidase activities, and glutathione content. Treatments with quercetin and rutin significantly repressed the elevated expression of liver p53 and TNF-α and enhanced Nrf2 expression. Furthermore, the treatments significantly reduced DXR-induced liver histological changes. In conclusion, rutin and quercetin either alone or in combination may have potential preventive effects against DXR-induced hepatotoxicity through inhibiting oxidative stress, inflammation, and apoptosis as well as modulating the Nrf2 expression.

Novel Therapeutics for Anthracycline Induced Cardiotoxicity

Anthracyclines remain an essential component of the treatment of many hematologic and solid organ malignancies, but has important implications on cardiovascular disease. Anthracycline induced cardiotoxicity (AIC) ranges from asymptomatic LV dysfunction to highly morbid end- stage heart failure. As cancer survivorship improves, the detection and treatment of AIC becomes more crucial to improve patient outcomes. Current treatment modalities for AIC have been largely extrapolated from treatment of conventional heart failure, but developing effective therapies specific to AIC is an area of growing research interest. This review summarizes the current evidence behind the use of neurohormonal agents, dexrazoxane, and resynchronization therapy in AIC, evaluates the clinical outcomes of advanced therapy and heart transplantation in AIC, and explores future horizons for treatment utilizing gene therapy, stem cell therapy, and mechanism-specific targets.

Cardiotoxicity of Anticancer Drugs: Molecular Mechanisms and Strategies for Cardioprotection

Chemotherapy and targeted therapies have significantly improved the prognosis of oncology patients. However, these antineoplastic treatments may also induce adverse cardiovascular effects, which may lead to acute or delayed onset of cardiac dysfunction. These common cardiovascular complications, commonly referred to as cardiotoxicity, not only may require the modification, suspension, or withdrawal of life-saving antineoplastic therapies, with the risk of reducing their efficacy, but can also strongly impact the quality of life and overall survival, regardless of the oncological prognosis. The onset of cardiotoxicity may depend on the class, dose, route, and duration of administration of anticancer drugs, as well as on individual risk factors. Importantly, the cardiotoxic side effects may be reversible, if cardiac function is restored upon discontinuation of the therapy, or irreversible, characterized by injury and loss of cardiac muscle cells. Subclinical myocardial dysfunction induced by anticancer therapies may also subsequently evolve in symptomatic congestive heart failure. Hence, there is an urgent need for cardioprotective therapies to reduce the clinical and subclinical cardiotoxicity onset and progression and to limit the acute or chronic manifestation of cardiac damages. In this review, we summarize the knowledge regarding the cellular and molecular mechanisms contributing to the onset of cardiotoxicity associated with common classes of chemotherapy and targeted therapy drugs. Furthermore, we describe and discuss current and potential strategies to cope with the cardiotoxic side effects as well as cardioprotective preventive approaches that may be useful to flank anticancer therapies.

The cardioprotective effects of perindopril in a model of polymicrobial sepsis: The role of radical oxygen species and the inflammation pathway

Mortality rates associated with myocardial dysfunction due to sepsis and septic shock are generally high across the world. The present study focused on the antioxidant and anti-inflammatory effects of perindopril (PER) for the purpose of preventing the adverse effects of sepsis on the myocardium and developing new alternatives in treatment. The control group received only saline solution via the oral route for 4 days. The second group underwent cecal ligation puncture (CLP), and the third underwent CLP and received PER (2 mg/kg). Rats in the third group received 2 mg/kg PER per oral (p.o.) from 4 days before induction of sepsis. Thiobarbituric acid reactive species (TBARS), total thiol (-SH), interleukin-1 beta (IL-1β), IL-6, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and nuclear factor kappa B (NF-κB/p65) levels increased in the CLP groups. In contrast, PER (2 mg/kg) decreased the levels of biochemical parameters other than total-SH and decreased 8-OHdG, NF-κB/p65 immunopositivity in rat heart tissues. The data from this study show that impairment of the oxidant/antioxidant balance and inflammatory cytokine levels in favor of inflammation in heart tissue under septic conditions results in severe tissue damage. PER administration before sepsis was shown to exhibit antioxidant and anti-inflammatory properties by reducing these effects. This in turn increased the importance of PER as new evidence of its protective effects in heart tissue.

Thyme Oil and Thymol Counter Doxorubicin-Induced Hepatotoxicity via Modulation of Inflammation, Apoptosis, and Oxidative Stress

Doxorubicin (DOX) is an effective anticancer agent with a wide spectrum of activities. However, it has many adverse effects on various organs especially on the liver. Thymol, one of the major components of thyme oil, has biological properties that include anti-inflammatory and antioxidant activities. Thus, this study was designed to examine thyme oil and thymol for their ability to prevent doxorubicin-induced hepatotoxicity in Wistar rats. Hepatotoxicity was induced by an intraperitoneal injection of doxorubicin, at a dose of 2 mg/kg bw/week, for seven weeks. Doxorubicin-injected rats were supplemented with thyme oil and thymol at doses 250 and 100 mg/kg bw, respectively, four times/week by oral gavage for the same period. Treatment of rats with thyme oil and thymol reversed the high serum activities of AST, ALT, and ALP and total bilirubin, AFP, and CA19.9 levels, caused by doxorubicin. Thyme oil and thymol also reduced the high levels of TNF-α and the decreased levels of both albumin and IL-4. These agents ameliorated doxorubicin-induced elevation in hepatic lipid peroxidation and associated reduction in GSH content and GST and GPx activities. Further, the supplementation with thyme oil and thymol significantly augmented mRNA expression of the level of antiapoptotic protein Bcl-2 and significantly downregulated nuclear and cytoplasmic levels of the hepatic apoptotic mediator p53. Thus, thyme oil and thymol successfully counteracted doxorubicin-induced experimental hepatotoxicity via their anti-inflammatory, antioxidant, and antiapoptotic properties.

Chemotherapy-associated cardiomyopathy: Mechanisms of toxicity and cardioprotective strategies

OBJECTIVE

To describe the proposed mechanisms of chemotherapy-associated cardiomyopathy (CAC) and potential cardioprotective therapies for CAC including a comprehensive review of existing systematic analyses, guideline recommendations, and ongoing clinical trials.

DATA SOURCES

A literature search of MEDLINE was performed (from 1990 to June 2020) using the following search terms: anthracycline, trastuzumab, cardiomyopathy, cardiotoxicity, primary prevention, angiotensin-converting enzyme inhibitor (ACEI), angiotensin receptor blocker (ARB), beta blocker, dexrazoxane (DEX) as well as using individual names from select therapeutic categories.

STUDY SELECTION AND DATA EXTRACTION

Existing English language systematic analyses and guidelines were considered.

DATA SYNTHESIS

The mechanisms of CAC are multifaceted, but various cardioprotective therapies target many of these pathways. To date, anthracyclines and HER-2 targeted therapies have been the focus of cardioprotective trials to date as they are the most commonly implicated therapies in CAC. While traditional neurohormonal antagonists (ACEIs, ARBs, and beta blockers) and DEX performed favorably in many small clinical trials, the quality of available evidence remains limited. Hence, major guidelines lack consensus on an approach to primary prevention of CAC. Given the uncertain role of preventive therapy, monitoring for a symptomatic or asymptomatic decline in LV function is imperative with prompt evaluation should this occur. Numerous ongoing randomized controlled trials seek to either confirm the findings of these previous studies or identify new therapeutic agents to prevent CAC. Clinical implications are derived from the available literature as well as current guideline recommendations for CAC cardioprotection.

CONCLUSION

At this time, no single therapy has a clear cardioprotective benefit in preventing CAC nor is any therapy strongly recommended by current guidelines. Additional studies are needed to determine the optimal preventative regimens.

Mechanism and prevention strategy of a bidirectional relationship between heart failure and cancer (Review)

The relationship between cancer and heart failure has been extensively studied in the last decade. These studies have focused on describing heart injury caused by certain cancer treatments, including radiotherapy, chemotherapy and targeted therapy. Previous studies have demonstrated a higher incidence of cancer in patients with heart failure. Heart failure enhances an over-activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system, and subsequently promotes cancer development. Other studies have found that heart failure and cancer both have a common pathological origin, flanked by chronic inflammation in certain organs. The present review aims to summarize and describe the recent discoveries, suggested mechanisms and relationships between heart failure and cancer. The current review provides more ideas on clinical prevention strategies according to the pathological mechanism involved.

Molecular mechanisms of anthracycline cardiovascular toxicity

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

Captopril downregulates expression of Bax/cytochrome C/caspase-3 apoptotic pathway, reduces inflammation, and oxidative stress in cisplatin-induced acute hepatic injury

Cisplatin (Cis) is an effective cancer therapy commonly employed in many therapeutic regimens. However, treatment regimens that contain either a high dose or cumulative doses of Cis could trigger liver damage. A unique study demonstrated that captopril (Cap) protects against Cis-induced liver toxicity, but only some liver function enzymes and some antioxidant enzymes were investigated in that study. Our study aims to elucidate the protective mechanism of Cap against Cis liver toxicity. Acute liver toxicity was induced in rats by injecting a single Cis dose (7.5 mg/kg) in three groups (n = 6). Two groups were pre-treated with low (50 mg/kg) and high (100 mg/kg) Cap doses for one week before Cis injection, and the third group was injected with Cis only. The high Cap dose significantly improved liver function markers (ALT, AST, and ALP) and hepatic tissue pathology. The low Cap dose significantly improved ALP and, to a lesser extent, hepatic tissue pathology. Both Cap doses significantly decreased liver contents of MDA, IL-1β, and cleaved caspase-3; and liver protein expression of TNF-α, Bax, and caspase-3. The high Cap dose significantly increased liver contents of GSH, GPx, CAT, and SOD, and the liver protein expression of Bcl2. Moreover, only the high Cap dose significantly decreased liver IL-6 content and cytochrome C protein expression. Cap did not inhibit the antitumor impact of Cis against HCT116 cancer cells. Therefore, Cap restricts Cis-induced liver toxicity by reducing inflammation and apoptosis and augmenting the antioxidant system.

Mechanisms of anthracycline-mediated cardiotoxicity and preventative strategies in women with breast cancer

While anthracyclines (ACs) are a class of chemotherapeutic agents that have improved the prognosis of many women with breast cancer, it is one of the most cardiotoxic agents used to treat cancer. Despite their reported dose-dependent cardiotoxicity, AC-based chemotherapy has become the mainstay of breast cancer therapy due to its efficacy. Elucidating the mechanisms of anthracycline-mediated cardiotoxicity and associated therapeutic interventions continue to be the main focus in the field of cardio-oncology. Herein, we summarized the current literature surrounding the mechanisms of anthracycline-induced cardiotoxicity, including the role of topoisomerase II inhibition, generation of reactive oxygen species, and elevations in free radicals. Furthermore, this review highlights the molecular mechanisms of potential cardioprotective interventions in this setting. The benefits of pharmaceuticals, including dexrazoxane, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, statins, and antioxidants in this setting, are reviewed. Finally, the mechanisms of emerging preventative interventions within this patient population including nutraceuticals and aerobic exercise are explored.

Antioxidant Approach as a Cardioprotective Strategy in Chemotherapy-Induced Cardiotoxicity

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

An Overview of Pharmacological and Non-Pharmacological Treatment as a Useful Tool for the Protection from Cardiotoxicity of Antineoplastic Drugs

Unfortunately, in patients with cancer disease, clinical application of antineoplastic drug results in severe side effects of cardiotoxicity.

We aim to review the research focused on elimination or reduction of antineoplastic drug-induced cardiotoxicity without affecting its anticancer efficacy by different agens.

This study is based on pertinent papers that were retrieved by a selective search using relevant keywords in PubMed and ScienceDirect. Based on mentioned purpose, various strategies were investigated and proposed, and thousands of compounds were screened. The literature mainly focusing on drugs, natural products and herb extracts with therapeutic efficacies as well as non-pharmacological treatment against differently induced cardiotoxicity during treatment in patients with cancers.

Larger future studies are necessary to reach a point of secure cytostatic therapy, improved patient survival and quality of life. Until that moment, baseline and serial cardiac evaluation is recommended to facilitate early identification and treatment of cardiotoxicity.

Prophylactic, single-drug cardioprotection in a comparative, experimental study of doxorubicin-induced cardiomyopathy

Background

Cardiomyopathy is a common side effect of doxorubicin (DOX) chemotherapy. Despite intensive research efforts in the field, there is still no evidence available for routine cardioprotective prophylaxis to prevent cardiotoxicity in the majority of oncological patients at low risk of cardiovascular disease. We have recently demonstrated the advantages of a prophylactic, combined heart failure therapy in an experimental model of DOX-induced cardiomyopathy. In the current work, we focus on individually applied prophylactic medications studied in the same translational environment to clarify their distinct roles in the prevention of DOX cardiotoxicity.

Methods

Twelve-week-old male Wistar rats were divided into 5 subgroups. Prophylactic β-blocker (BB, bisoprolol), angiotensin-converting enzyme inhibitor (ACEI, perindopril) or aldosterone antagonist (AA, eplerenone) treatments were applied 1 week before DOX administration, then 6 cycles of intravenous DOX chemotherapy were administered. Rats receiving only intravenous DOX or saline served as positive and negative controls. Blood pressure, heart rate, body weight, and echocardiographic parameters were monitored in vivo. Two months after the last DOX administration, the animals were sacrificed, and their heart and serum samples were frozen in liquid nitrogen for histological, mechanical, and biochemical measurements.

Results

All prophylactic treatments increased the survival of DOX-receiving animals. The lowest mortality rates were seen in the BB and ACEI groups. The left ventricular ejection fraction was only preserved in the BB group. The DOX-induced increase in the isovolumetric relaxation time could not be prevented by any prophylactic treatment. A decreased number of apoptotic nuclei and a preserved myocardial ultrastructure were found in all groups receiving prophylactic cardioprotection, while the DOX-induced fibrotic remodelling and the increase in caspase-3 levels could only be substantially prevented by the BB and ACEI treatments.

Conclusion

Primary prophylaxis with cardioprotective agents like BB or ACEI has a key role in the prevention of DOX-induced cardiotoxicity in healthy rats. Future human studies are necessary to implement this finding in the clinical management of oncological patients free of cardiovascular risk factors.

Anthracycline-induced cardiotoxicity and renin-angiotensin-aldosterone system-from molecular mechanisms to therapeutic applications

Few millions of new cancer cases are diagnosed worldwide every year. Due to significant progress in understanding cancer biology and developing new therapies, the mortality rates are decreasing with many of patients that can be completely cured. However, vast majority of them require chemotherapy which comes with high medical costs in terms of adverse events, of which cardiotoxicity is one of the most serious and challenging. Anthracyclines (doxorubicin, epirubicin) are a class of cytotoxic agents used in treatment of breast cancer, sarcomas, or hematological malignancies that are associated with high risk of cardiotoxicity that is observed in even up to 30% of patients and can be diagnosed years after the therapy. The mechanism, in which anthracyclines cause cardiotoxicity are not well known, but it is proposed that dysregulation of renin-angiotensin-aldosterone system (RAAS), one of main humoral regulators of cardiovascular system, may play a significant role. There is increasing evidence that drugs targeting this system can be effective in the prevention and treatment of anthracycline-induced cardiotoxicity what has recently found reflection in the recommendation of some scientific societies. In this review, we comprehensively describe possible mechanisms how anthracyclines affect RAAS and lead to cardiotoxicity. Moreover, we critically review available preclinical and clinical data on use of RAAS inhibitors in the primary and secondary prevention and treatment of cardiac adverse events associated with anthracycline-based chemotherapy.

Ameliorative effects of melatonin against solid Ehrlich carcinoma progression in female mice

The current work estimated the antitumour efficacy of melatonin (MLT) on the growth of Ehrlich ascites carcinoma cells inoculated intramuscularly into the hind limbs of female BALB/c mice and to compare its effects with those of adriamycin (ADR). After solid tumours developed, the animals were divided into the three following groups: the tumour-bearing control, MLT-treated (20 mg/kg body weight) and ADR-treated (10 mg/kg body weight) groups. The results showed a significant reduction in the tumour masses of the treated animals in comparison with those of the control group. There were a significant decrease in the malondialdehyde level and a significant elevation of the glutathione concentration and the superoxide dismutase and catalase activities in the MLT and ADR groups. The current study indicated the increased expression levels of P53, caspase-3 and caspase-9 and the decreased expression levels of the rRNA and Bcl2. The MLT and ADR treatments resulted in histological changes, such as a marked degenerative area, the necrosis of neoplastic cells, the appearance of different forms of apoptotic cells and giant cells with condensed chromatin, and a deeply eosinophilic cytoplasm. The MLT and ADR treatments also significantly decreased the Ki-67 protein and vascular endothelial growth factor (VEGF) expression levels in the tumour masses. In conclusion, similar to ADR-treated tumour-bearing mice, MLT suppressed the growth and proliferation of tumour by inducing apoptosis and by inhibiting tumour vascularization. The current data recommend MLT as a safe natural chemotherapeutic adjuvant to overcome cancer progression after a clinical trial validates these results.

From Molecular Mechanisms to Clinical Management of Antineoplastic Drug-Induced Cardiovascular Toxicity: A Translational Overview

Significance: Antineoplastic therapies have significantly improved the prognosis of oncology patients. However, these treatments can bring to a higher incidence of side-effects, including the worrying cardiovascular toxicity (CTX). Recent Advances: Substantial evidence indicates multiple mechanisms of CTX, with redox mechanisms playing a key role. Recent data singled out mitochondria as key targets for antineoplastic drug-induced CTX; understanding the underlying mechanisms is, therefore, crucial for effective cardioprotection, without compromising the efficacy of anti-cancer treatments. Critical Issues: CTX can occur within a few days or many years after treatment. Type I CTX is associated with irreversible cardiac cell injury, and it is typically caused by anthracyclines and traditional chemotherapeutics. Type II CTX is generally caused by novel biologics and more targeted drugs, and it is associated with reversible myocardial dysfunction. Therefore, patients undergoing anti-cancer treatments should be closely monitored, and patients at risk of CTX should be identified before beginning treatment to reduce CTX-related morbidity. Future Directions: Genetic profiling of clinical risk factors and an integrated approach using molecular, imaging, and clinical data may allow the recognition of patients who are at a high risk of developing chemotherapy-related CTX, and it may suggest methodologies to limit damage in a wider range of patients. The involvement of redox mechanisms in cancer biology and anticancer treatments is a very active field of research. Further investigations will be necessary to uncover the hallmarks of cancer from a redox perspective and to develop more efficacious antineoplastic therapies that also spare the cardiovascular system.

Management of Cancer Therapeutics-Related Cardiac Dysfunction

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

Anthracycline-induced cardiotoxicity: A multicenter randomised trial comparing two strategies for guiding prevention with enalapril: The International CardioOncology Society-one trial

BACKGROUND

Troponin changes over time have been suggested to allow for an early diagnosis of cardiac injury ensuing cancer chemotherapy; cancer patients with troponin elevation may benefit of therapy with enalapril. It is unknown whether a preventive treatment with enalapril may further increase the benefit.

METHODS

The International CardioOncology Society-one trial (ICOS-ONE) was a controlled, open-label trial conducted in 21 Italian hospitals. Patients were randomly assigned to two strategies: enalapril in all patients started before chemotherapy (CT; 'prevention' arm), and enalapril started only in patients with an increase in troponin during or after CT ('troponin-triggered' arm). Troponin was assayed locally in 2596 blood samples, before and after each anthracycline-containing CT cycle and at each study visit; electrocardiogram and echocardiogram were done at baseline, and at 1, 3, 6 and 12-month follow-up. Primary outcome was the incidence of troponin elevation above the threshold.

FINDINGS

Of the 273 patients, 88% were women, mean age 51 ± 12 years. The majority (76%) had breast cancer, 3% had a history of hypertension and 4% were diabetic. Epirubicin and doxorubicin were most commonly prescribed, with median cumulative doses of 360 [270-360] and 240 [240-240] mg/m², respectively. The incidence of troponin elevation was 23% in the prevention and 26% in the troponin-triggered group (p = 0.50). Three patients (1.1%) -two in the prevention, one in the troponin-triggered group-developed cardiotoxicity, defined as 10% point reduction of LV ejection fraction, with values lower than 50%.

INTERPRETATION

Low cumulative doses of anthracyclines in adult patients with low cardiovascular risk can raise troponins, without differences between the two strategies of giving enalapril. Considering a benefit of enalapril in the prevention of LV dysfunction, a troponin-triggered strategy may be more convenient.

Antineoplastic Drug-Induced Cardiotoxicity: A Redox Perspective

Antineoplastic drugs can be associated with several side effects, including cardiovascular toxicity (CTX). Biochemical studies have identified multiple mechanisms of CTX. Chemoterapeutic agents can alter redox homeostasis by increasing the production of reactive oxygen species (ROS) and reactive nitrogen species RNS. Cellular sources of ROS/RNS are cardiomyocytes, endothelial cells, stromal and inflammatory cells in the heart. Mitochondria, peroxisomes and other subcellular components are central hubs that control redox homeostasis. Mitochondria are central targets for antineoplastic drug-induced CTX. Understanding the mechanisms of CTX is fundamental for effective cardioprotection, without compromising the efficacy of anticancer treatments. Type 1 CTX is associated with irreversible cardiac cell injury and is typically caused by anthracyclines and conventional chemotherapeutic agents. Type 2 CTX, associated with reversible myocardial dysfunction, is generally caused by biologicals and targeted drugs. Although oxidative/nitrosative reactions play a central role in CTX caused by different antineoplastic drugs, additional mechanisms involving directly and indirectly cardiomyocytes and inflammatory cells play a role in cardiovascular toxicities. Identification of cardiologic risk factors and an integrated approach using molecular, imaging, and clinical data may allow the selection of patients at risk of developing chemotherapy-related CTX. Although the last decade has witnessed intense research related to the molecular and biochemical mechanisms of CTX of antineoplastic drugs, experimental and clinical studies are urgently needed to balance safety and efficacy of novel cancer therapies.

Preventing antiblastic drug-related cardiomyopathy: old and new therapeutic strategies

Because of the recent advances in chemotherapeutic protocols, cancer survival has improved significantly, although cardiovascular disease has become a major cause of morbidity and mortality among cancer survivors: in addition to the well-known cardiotoxicity (CTX) from anthracyclines, biologic drugs that target molecules that are active in cancer biology also interfere with cardiovascular homeostasis.Pharmacological and non-pharmacological strategies to protect the cardiovascular structure and function are the best approaches to reducing the prevalence of cardiomyopathy linked to anticancer drugs. Extensive efforts have been devoted to identifying and testing strategies to achieve this end, but little consensus has been reached on a common and shared operability.Timing, dose and mode of chemotherapy administration play a crucial role in the development of acute or late myocardial dysfunction. Primary prevention initiatives cover a wide area that ranges from conventional heart failure drugs, such as β-blockers and renin-angiotensin-aldosterone system antagonists to nutritional supplementation and physical training. Additional studies on the pathophysiology and cellular mechanisms of anticancer-drug-related CTX will enable the introduction of novel therapies.We present various typologies of prevention strategies, describing the approaches that have already been used and those that could be effective on the basis of a better understanding of pharmacokinetic and pharmacodynamic CTX mechanisms.

The angiotensin-converting enzyme inhibitor captopril rescues mice from endotoxin-induced lethal hepatitis

The renin–angiotensin system is classically regarded as a crucial regulator of circulatory homeostasis, but recent studies also revealed its pro-inflammatory roles. The beneficial effects of the angiotensin-converting enzyme inhibitor (ACEI) in severe inflammatory injury in the lung and heart have been previously reported, but its potential effects on lethal hepatitis were unknown. In this study, a mouse model with LPS/d-galactosamine (GalN)-induced fulminant hepatitis were used to test the protective potential of captopril, a representative ACEI. The results indicated that treatment with captopril significantly decreased the plasma level of alanine aminotransferase and aspartate aminotransferase, alleviated the histopathological damage of the liver tissue and improve the survival rate of LPS/GalN-challenged mice. These effects were accompanied by reduced mRNA levels of TNF-α and IL-6 in the liver, and decreased protein level of TNF-α and IL-6 in the plasma. In addition, the activation of caspases 3, 8 and 9, and the presence of TUNEL-positive apoptotic cells, were also suppressed by captopril treatment. The above evidence suggested that the renin–angiotensin system might be involved in the development of LPS/GalN-induced fulminant hepatitis and ACEI might have potential value in lethal hepatitis.

Doxorubicin-Mediated Cardiotoxicity: Role of Mitochondrial Connexin 43

Doxorubicin is the highly effective anthracycline, but its clinical use is limited by cardiotoxicity and consequent dysfunction. It has been proposed that the etiology of this is related to mitochondrial dysfunction. Connexin 43 (Cx43), the principal protein building block of cardiac gap junctions and hemichannels, plays an important role in cardioprotection. Recent reports confirmed the presence of Cx43 in the mitochondria as well. In this study, the role of mitochondrial Cx43 was evaluated 3 or 6 h after Doxorubicin administration to the rat heart cell line H9c2. Pharmacological inhibition of Hsp90 demonstrated that the mitochondrial Cx43 conferred cardioprotection by reducing cytosolic and mitochondrial reactive oxygen species production, mitochondrial calcium overload and mitochondrial membrane depolarization and cytochrome c release. In conclusion, our study demonstrates that Cx43 plays an important role in the protection of cardiac cells from Doxorubicin-induced toxicity.

The Cooperative Effect of Local Angiotensin-II in Liver with Adriamycin Hepatotoxicity on Mitochondria

BACKGROUND

Adriamycin (ADR) is a drug used clinically for anticancer treatment; however, it causes adverse effects in the liver. The mechanism by which these adverse effects occur remains unclear, impeding efforts to enhance the therapeutic effects of ADR. Its hepatotoxicity might be related to increasing reactive oxygen species (ROS) and mitochondrial dysfunction. The interaction between ADR and the local renin-angiotensin system (RAS) in the liver is unclear. ADR might activate the RAS. Angiotensin-II (Ang-II) leads to ROS production and mitochondrial dysfunction. In the present study we investigated whether ADR's hepatotoxicity interacts with local RAS in causing oxidative stress resulting from mitochondrial dysfunction in the rat liver.

MATERIAL/METHODS

Rats were divided into 5 groups: control, ADR, co-treated ADR with captopril, co-treated ADR with Aliskiren, and co-treated ADR with both captopril and Aliskiren. Mitochondria and cytosol were separated from the liver, then biochemical measurements were made from them. Mitochondrial membrane potential (MMP) and ATP levels were evaluated.

RESULTS

ADR remarkably decreased MMP and ATP in liver mitochondria (p<0.05). Co-administration with ADR and Aliskiren and captopril improved the dissipation of MMP (p<0.05). The decreased ATP level was restored by treatment with inhibitors of ACE and renin.

CONCLUSIONS

Angiotensin-II may contribute to hepatotoxicity of in the ADR via mitochondrial oxidative production, resulting in the attenuation of MMP and ATP production.

Cancer Therapy-Related Cardiac Dysfunction and Heart Failure: Part 2: Prevention, Treatment, Guidelines, and Future Directions

Success with oncologic treatment has allowed cancer patients to experience longer cancer-free survival gains. Unfortunately, this success has been tempered by unintended and often devastating cardiac complications affecting overall patient outcomes. Cardiac toxicity, specifically the association of several cancer therapy agents with the development of left ventricular dysfunction and cardiomyopathy, is an issue of growing concern. Although the pathophysiologic mechanisms behind cardiac toxicity have been characterized, there is currently no evidence-based approach for monitoring and management of these patients. In the first of a 2-part review, we discuss the epidemiologic, pathophysiologic, risk factors, and imaging aspects of cancer therapy-related cardiac dysfunction and heart failure. In this second part, we discuss the prevention and treatment aspects in these patients and conclude with highlighting the evidence gaps and future directions for research in this area.

Attenuation of lipopolysaccharide-induced acute lung injury after (pro)renin receptor blockade

PURPOSE/AIM

We performed a randomized, prospective animal study to investigate whether inhibiting the renin-angiotensin system with a (pro)renin receptor blocker (PRRB) prevents acute lung injury (ALI) in a rodent model.

MATERIALS

We used Thirty-six male Sprague-Dawley rats. We administered lipopolysaccharide (LPS; 2 mg/kg) intratracheally with or without PRRB pretreatment (1 mg/kg/d).

METHODS

We performed bronchoalveolar lavage (BAL) and lung removal at 4 h after LPS administration and measured levels of inflammatory cytokines, high mobility group box 1 (HMGB-1) protein, and total protein in bronchoalveolar lavage fluid (BALF). Myeloperoxidase (MPO) activity was detected in lung tissue homogenates using a sensitive ELISA. We performed hematoxylin and eosin staining and immunohistochemical staining for nonproteolytically activated prorenin in the left lung.

RESULTS

The PRRB decreased leukocyte counts and total protein, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-2, IL-6, and IL-10 levels in the BALF and MPO activity in lung tissue. The PRRB reduced interstitial edema, hemorrhage, and the neutrophil count in the lung tissues. Consistent with the reduction in lung tissue damage, immunohistochemical staining showed that the PRRB decreased the amount of nonproteolytically activated prorenin.

CONCLUSIONS

The PRRB blocked LPS-induced inflammatory response in the lung and protected against ALI. Therefore, it is a potential therapeutic agent for preventing ALI.

The role of renin angiotensin system antagonists in the prevention of doxorubicin and trastuzumab induced cardiotoxicity

Background

Cardio-Oncology is an evolving discipline that focuses on the management of cancer patients who develop cardiovascular complications as a result of their treatment. Although the current combination of surgical resection, radiation, and chemotherapy may lead to a cure in cancer patients, the administration of anti-cancer drugs, in particular Doxorubicin (DOX) and Trastuzumab (TRZ), is associated with an increased risk of cardiotoxicity. Little is known on the potential cardioprotective role of renin angiotensin system (RAS) antagonists in the prevention of DOX+TRZ mediated cardiotoxicity.

Objective

The aim of the study was to determine whether RAS antagonists would be useful in attenuating DOX+TRZ induced cardiotoxicity.

Methods

A total of 240 C57Bl/6 mice were randomized to prophylactic treatment with placebo, Aliskiren, Perindopril, or Valsartan for a total of 13 weeks. Within each arm, mice received treatment with either DOX, TRZ, or the combination of both drugs. Serial murine echocardiography was performed weekly to characterize the degree of cardiovascular remodeling within each group.

Results

In wild-type (WT) mice treated with DOX+TRZ, LV end diastolic internal diameter (LVID) increased from 3.1 ± 0.2 mm at baseline to 4.6 ± 0.3 mm at week 13 (p < 0.05) and the LV fractional shortening (FS) decreased from 52 ± 2% at baseline to 26 ± 2% at week 13 (p < 0.05). Prophylactic treatment with Aliskiren, Perindopril, or Valsartan attenuated the degree of LV cavity dilatation with LVID dimensions of 3.9 ± 0.2 mm, 4.1 ± 0.2 mm, and 4.2 ± 0.1 mm at week 13, respectively (p < 0.05). Similarly, prophylactic treatment with Aliskiren, Perindopril, or Valsartan was partially cardioprotective with FS of 40 ± 1%, 32 ± 1%, and 33 ± 2% at week 13, respectively (p < 0.05). As compared to WT mice receiving DOX+TRZ, prophylactic treatment with RAS inhibition was also associated with improved survival, corroborating the echocardiographic findings.

Conclusion

The cardiotoxic effects of DOX+TRZ were partially attenuated by the prophylactic administration of RAS antagonists in a chronic murine model of chemotherapy induced cardiac dysfunction.

Cardiac risk in the treatment of breast cancer: assessment and management

As the number of long-term breast cancer survivors has increased, the side effects of adjuvant cancer therapy, such as cardiac toxicity, remain clinically important. Although the cardiac toxicity due to anthracyclines, radiotherapy, or trastuzumab is well-documented, several issues need to be clarified and are the subjects of extensive ongoing clinical research. This review summarizes the incidence of cardiac toxicity due to breast cancer adjuvant therapy and highlights the current trends in early detection and management of cardiac toxicities.

Use of biomarkers for the assessment of chemotherapy-induced cardiac toxicity

OBJECTIVES

To review the evidence for the use of various biomarkers in the detection of chemotherapy associated cardiac damage.

DESIGN AND METHODS

Pubmed.gov was queried using the search words chemotherapy and cardiac biomarkers with the filters of past 10years, humans, and English language. An emphasis was placed on obtaining primary research articles looking at the utility of biomarkers for the detection of chemotherapy-mediated cardiac injury.

RESULTS

Biomarkers may help identify patients undergoing treatment who are at high risk for cardiotoxicity and may assist in identification of a low risk cohort that does not necessitate continued intensive screening. cTn assays are the best studied biomarkers in this context and may represent a promising and potentially valuable modality for detecting cardiac toxicity in patients undergoing chemotherapy. Monitoring cTnI levels may provide information regarding the development of cardiac toxicity before left ventricular dysfunction becomes apparent on echocardiography or via clinical symptoms. A host of other biomarkers have been evaluated for their utility in the field of chemotherapy related cardiac toxicity with intermittent success; further trials are necessary to determine what role they may end up playing for prediction and prognostication in this setting.

CONCLUSIONS

Biomarkers represent an exciting potential complement or replacement for echocardiographic monitoring of chemotherapy related cardiac toxicity which may allow for earlier realization of the degree of cardiac damage occurring during treatment, creating the opportunity for more timely modulation of therapy.

Can short-term fasting protect against doxorubicin-induced cardiotoxicity?

Doxorubicin (Dox) is one of the most effective chemotherapeutic agents used in the treatment of several types of cancer. However the use is limited by cardiotoxicity. Despite extensive investigation into the mechanisms of toxicity and preventative strategies, Dox-induced cardiotoxicity still remains a major cause of morbidity and mortality in cancer survivors. Thus, continued research into preventative strategies is vital. Short-term fasting has proven to be cardioprotective against a variety of insults. Despite the potential, only a few studies have been conducted investigating its ability to prevent Dox-induced cardiotoxicity. However, all show proof-of-principle that short-term fasting is cardioprotective against Dox. Fasting affects a plethora of cellular processes making it difficult to discern the mechanism(s) translating fasting to cardioprotection, but may involve suppression of insulin and insulin-like growth factor-1 signaling with stimulated autophagy. It is likely that additional mechanisms also contribute. Importantly, the literature suggests that fasting may enhance the antitumor activity of Dox. Thus, fasting is a regimen that warrants further investigation as a potential strategy to prevent Dox-induced cardiotoxicity. Future research should aim to determine the optimal regimen of fasting, confirmation that this regimen does not interfere with the antitumor properties of Dox, as well as the underlying mechanisms exerting the cardioprotective effects.

Chemotherapy-Induced Cardiotoxicity: Pathophysiology and Prevention

Along with the remarkable progress registered in oncological treatment that led to increased survival of cancer patients, treatment-related comorbidities have also become an issue for these long-term survivors. Of particular interest is the development of cardiotoxic events, which, even when asymptomatic, not only have a negative impact on the patient`s cardiac prognosis, but also considerably restrict therapeutic opportunities. The pathophysiology of cytostatic-induced cardiotoxicity implies a series of complex and intricate mechanisms, whose understanding enables the development of preventive and therapeutic strategies. Securing cardiac function is an ongoing challenge for the pharmaceutical industry and the physicians who have to deal currently with these adverse reactions. This review focuses on the main mechanism of cardiac toxicity induced by anticancer drugs and especially on the current strategies applied for preventing and minimizing the cardiac side effects.

Protective effects of onion (Allium cepa) extract against doxorubicin-induced hepatotoxicity in rats

Background/aim:

Doxorubicin (DOX) is a widely used and potent chemotherapeutic agent. However, serious dose-limiting toxicity through generation of free oxygen radicals is a commonly encountered clinical problem. The aim of the current study was to assess the protective role of onion ( Allium cepa) extract (ACE) against DOX-induced hepatotoxicity in rats.

Method:

A total of 24 rats were randomly divided into 3 equal experimental groups: (1) DOX; (2) ACE + DOX; and (3) control groups. ACE was given orally as 1 mL of fresh ACE juice for 14 consecutive days followed by DOX injection. DOX was injected intraperitoneally in a single dose of 30 mg/kg body weight to induce hepatotoxicity, and the rats were killed after 48 h from injection. Control group was given saline only.

Results:

In the ACE pretreated group (ACE + DOX), serum aspartate transaminase, alanine transaminase, and tissue malondialdehyde and glutathione levels were significantly lower, while superoxide dismutase and glutathione peroxidase were higher compared with the DOX group. The histopathological examination of liver specimens revealed parenchymal necrosis, proliferation of biliary duct in DOX group; while ACE pretreatment provided marked reduction in these changes.

Conclusion:

Our study indicates that pretreatment with ACE protects against DOX-induced hepatotoxicity due to the antioxidant properties of ACE. Further studies on efficacy of antioxidant treatment by ACE in DOX-mediated toxicity and underlying mechanisms would provide a better explanation.

Protective effect of spin-labeled 1-ethyl-1-nitrosourea against oxidative stress in liver induced by antitumor drugs and radiation

This study was carried out to investigate possible protection effect of 1-ethyl-3-[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)]-1-nitrosourea (SLENU), synthesized in our laboratory, against oxidative liver injuries induced in mice treated by antitumor drugs: doxorubicin (DOX), bleomycin (BLM), or gamma irradiation (R). Specifically, alterations in some biomarkers of oxidative stress, such as lipid peroxidation products measured as malondialdehyde (MDA) levels and activities of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), were studied in liver homogenates isolated from tumor bearing C57 black mice after i.p. treatment with solutions of DOX (60 mg/kg), BLM (60 mg/kg), or after total body gamma-irradiation with a single dose of 5 Gy. The same biomarkers were also measured after i.p. pretreatment of mice with SLENU (100 mg/kg). Statistical significant increased MDA levels and SOD and CAT enzymes activities were found in the liver homogenates of tumor bearing mice after alone treatment with DOX or gamma-irradiation compared to the control mice, while these parameters were insignificantly increased after BLM administration compared to the same controls.

Biocompatible microemulsion modifies the pharmacokinetic profile and cardiotoxicity of doxorubicin

Doxorubicin (DOX) is an anthracycline antibiotic with a broad antitumor spectrum. However, the clinical use of DOX is limited because of its cardiotoxicity, a dose-dependent effect. Colloidal drug delivery systems, such as microemulsions (MEs), allow the incorporation of drugs, modifying the pharmacokinetic (PK) profile and toxic effects. In this study, we evaluated the PK profile and cardiotoxicity of a new DOX ME (DOX-ME). The PK profile of DOX-ME was determined and compared with that of the conventional DOX after single-dose administration (6 mg/kg, intravenous) in male Wistar rats (n = 12 per group). The cardiotoxicity of DOX formulations was evaluated by serum creatine kinase MB (CKMB) activity in both animal groups before and after drug administration. The plasma DOX measurements were performed by high-performance liquid chromatography with fluorescence detection, and the CKMB levels were assayed using the CKMB Labtest® kit. The ME system showed a significant increase in plasma DOX concentrations and lower distribution volume when compared with conventional DOX. Serum CKMB activity increased after conventional DOX administration but was unchanged in the DOX-ME group. These results demonstrate modifications in drug access to susceptible sites using DOX-ME. DOX-ME displayed features that make it a promising system for future therapeutic application.

Metformin rescues the myocardium from doxorubicin-induced energy starvation and mitochondrial damage in rats

Clinical use of doxorubicin (DOX) is limited by its cardiotoxic side effects. Recent studies established that metformin (MET), an oral antidiabetic drug, possesses an antioxidant activity. However, whether it can protect against DOX-induced energy starvation and mitochondrial damage has not been reported. Our results, in a rat model of DOX-induced cardiotoxicity, show that DOX treatment significantly increased serum levels of LDH and CK-MB, indicators of cardiac injury, and induced expression of hypertrophic gene markers. DOX also caused marked decreases in the cardiac levels of glutathione, CoA-SH and ATP, and mRNA expression of catalase and NQO-1. These biochemical changes were associated with myocardial histopathological and ultrastructural deteriorations, as observed by light and electron microscopy, respectively. Cotreatment with MET (500 mg/kg) eliminated all DOX-induced biochemical, histopathological, and ultrastructural changes. These findings demonstrate that MET successfully prevents DOX-induced cardiotoxicity in vivo by inhibiting DOX-induced oxidative stress, energy starvation, and depletion of intramitochondrial CoA-SH.

Management of chemotherapy induced cardiomyopathy

Chemotherapy related cardiac dysfunction (CRCD) is a serious complication of anticancer therapy. CRCD can be classified into two types. Type I CRCD is exemplified by anthracyline- induced cardiac dysfunction and type II CRCD is exemplified by trastuzumab- induced cardiac dysfunction. The mechanism of cardiac toxicity in both types is not well defined. Certain risk factors may play a role in developing the cardiac injury, most importantly, the cumulative dose when dealing with anthracycline induced cardiotoxicity. Establishing an early diagnosis and initiating early treatment may be an important step in preventing irreversible cardiac injury especially in type I CRCD. Currently there are no guidelines developed specifically for the treatment of chemotherapy induced cardiomyopathy (CIC), however a few small studies support the use of neurohormonal antagonists in the treatment and prevention of CIC. Large multi- centers trials are needed to establish guidelines for CIC. Until then, we advocate following the American College of Cardiology/ American Heart Association (ACC/AHA) and Heart Failure Society of America (HFSA) guidelines. Additionally, a close collaboration between the patient's cardiologist and oncologist is strongly recommended in order to establish a long term plan for the patient.

Pretreatment with angiotensin-converting enzyme inhibitor improves doxorubicin-induced cardiomyopathy via preservation of mitochondrial function

OBJECTIVE

Doxorubicin is a widely used chemotherapy drug, but its application is associated with cardiotoxicity. Free radical generation and mitochondrial dysfunction are thought to contribute to doxorubicin-induced cardiac failure. Angiotensin-converting enzyme inhibitors are commonly used as cardioprotective agents and have recently been shown in clinical studies to be efficacious in the prevention of anthracycline-induced heart failure. This study evaluated a mechanism for these protective effects by testing the ability of the angiotensin-converting enzyme inhibitor enalapril to preserve mitochondrial function in a model of chronic doxorubicin treatment in rats.

METHODS

Sprague Dawley rats were divided into 3 groups and followed for a total of 10 weeks: (1) control-untreated, (2) doxorubicin treated, and (3) doxorubicin + enalapril treated. Doxorubicin was administered via intraperitoneal injection at weekly intervals from weeks 2 to 7. Enalapril was administered in the drinking water of the doxorubicin + enalapril group for the study duration.

RESULTS

Doxorubicin treatment produced a significant loss in left ventricular contractility (P < .05), decrease in mitochondrial function via impairment of state-3 respiration, decrease in the cytosolic fraction of adenosine triphosphate, and up-regulation of free radical production. Enalapril significantly attenuated the decrease in percent fractional shortening (P < .05) and prevented the doxorubicin-associated reduction in respiratory efficiency and cytosolic adenosine triphosphate content (P < .05). Enalapril also abolished the robust doxorubicin-induced increase in free radical formation.

CONCLUSIONS

Administration of enalapril attenuates doxorubicin-induced cardiac dysfunction via preservation of mitochondrial respiratory efficiency and reduction in doxorubicin-associated free radical generation.