The decrease of NAD(P)H:quinone oxidoreductase 1 activity and increase of ROS production by NADPH oxidases are early biomarkers in doxorubicin cardiotoxicity

Mechanisms of Cardiovascular Toxicities Induced by Cancer Therapies and Promising Biomarkers for Their Prediction: A Scoping Review

AIM

With the advancement of anti-cancer medicine, cardiovascular toxicities due to cancer therapies are common in oncology patients, resulting in increased mortality and economic burden. Cardiovascular toxicities caused by cancer therapies include different severities of cardiomyopathy, arrhythmia, myocardial ischaemia, hypertension, and thrombosis, which may lead to left ventricular dysfunction and heart failure. This scoping review aimed to summarise the mechanisms of cardiovascular toxicities following various anti-cancer treatments and potential predictive biomarkers for early detection.

METHODS

PubMed, Cochrane, Embase, Web of Science, Scopus, and CINAHL databases were searched for original studies written in English related to the mechanisms of cardiovascular toxicity induced by anti-cancer therapies, including chemotherapy, targeted therapy, immunotherapy, radiation therapy, and relevant biomarkers. The search and title/abstract screening were conducted independently by two reviewers, and the final analysed full texts achieved the consensus of the two reviewers.

RESULTS

A total of 240 studies were identified based on their titles and abstracts. In total, 107 full-text articles were included in the analysis. Cardiomyocyte and endothelial cell apoptosis caused by oxidative stress injury, activation of cell apoptosis, blocking of normal cardiovascular protection signalling pathways, overactivation of immune cells, and myocardial remodelling were the main mechanisms. Promising biomarkers for anti-cancer therapies related to cardiovascular toxicity included placental growth factor, microRNAs, galectin-3, and myeloperoxidase for the early detection of cardiovascular toxicity.

CONCLUSION

Understanding the mechanisms of cardiovascular toxicity following various anti-cancer treatments could provide implications for future personalised treatment methods to protect cardiovascular function. Furthermore, specific early sensitive and stable biomarkers of cardiovascular system damage need to be identified to predict reversible damage to the cardiovascular system and improve the effects of anti-cancer agents.

Poncirus trifoliata Aqueous Extract Protects Cardiomyocytes against Doxorubicin-Induced Toxicity through Upregulation of NAD(P)H Dehydrogenase Quinone Acceptor Oxidoreductase 1

Doxorubicin (DOX), an anthracycline-based chemotherapeutic agent, is widely used to treat various types of cancer; however, prolonged treatment induces cardiomyotoxicity. Although studies have been performed to overcome DOX-induced cardiotoxicity (DICT), no effective method is currently available. This study investigated the effects and potential mechanisms of Poncirus trifoliata aqueous extract (PTA) in DICT. Changes in cell survival were assessed in H9c2 rat cardiomyocytes and MDA-MB-231 human breast cancer cells. The C57BL/6 mice were treated with DOX to induce DICT in vivo, and alterations in electrophysiological characteristics, serum biomarkers, and histological features were examined. The PTA treatment inhibited DOX-induced decrease in H9c2 cell viability but did not affect the MDA-MB-231 cell viability. Additionally, the PTA restored the abnormal heart rate, R-R interval, QT interval, and ST segment and inhibited the decrease in serum cardiac and hepatic toxicity indicators in the DICT model. Moreover, the PTA administration protected against myocardial fibrosis and apoptosis in the heart tissue of mice with DICT. PTA treatment restored DOX-induced decrease in the expression of NAD(P)H dehydrogenase quinone acceptor oxidoreductase 1 in a PTA concentration-dependent manner. In conclusion, the PTA inhibitory effect on DICT is attributable to its antioxidant properties, suggesting the potential of PTA as a phytotherapeutic agent for DICT.

Rafting on the Evidence for Lipid Raft-like Domains as Hubs Triggering Environmental Toxicants' Cellular Effects

The plasma membrane lipid rafts are cholesterol- and sphingolipid-enriched domains that allow regularly distributed, sub-micro-sized structures englobing proteins to compartmentalize cellular processes. These membrane domains can be highly heterogeneous and dynamic, functioning as signal transduction platforms that amplify the local concentrations and signaling of individual components. Moreover, they participate in cell signaling routes that are known to be important targets of environmental toxicants affecting cell redox status and calcium homeostasis, immune regulation, and hormonal functions. In this work, the evidence that plasma membrane raft-like domains operate as hubs for toxicants' cellular actions is discussed, and suggestions for future research are provided. Several studies address the insertion of pesticides and other organic pollutants into membranes, their accumulation in lipid rafts, or lipid rafts' disruption by polychlorinated biphenyls (PCBs), benzo[a]pyrene (B[a]P), and even metals/metalloids. In hepatocytes, macrophages, or neurons, B[a]P, airborne particulate matter, and other toxicants caused rafts' protein and lipid remodeling, oxidative changes, or amyloidogenesis. Different studies investigated the role of the invaginated lipid rafts present in endothelial cells in mediating the vascular inflammatory effects of PCBs. Furthermore, in vitro and in vivo data strongly implicate raft-localized NADPH oxidases, the aryl hydrocarbon receptor, caveolin-1, and protein kinases in the toxic mechanisms of occupational and environmental chemicals.

Essential Amino Acids-Rich Diet Increases Cardiomyocytes Protection in Doxorubicin-Treated Mice

BACKGROUND

Doxorubicin (Doxo) is a widely prescribed drug against many malignant cancers. Unfortunately, its utility is limited by its toxicity, in particular a progressive induction of congestive heart failure. Doxo acts primarily as a mitochondrial toxin, with consequent increased production of reactive oxygen species (ROS) and attendant oxidative stress, which drives cardiac dysfunction and cell death. A diet containing a special mixture of all essential amino acids (EAAs) has been shown to increase mitochondriogenesis, and reduce oxidative stress both in skeletal muscle and heart. So, we hypothesized that such a diet could play a favorable role in preventing Doxo-induced cardiomyocyte damage.

METHODS

Using transmission electron microscopy, we evaluated cells' morphology and mitochondria parameters in adult mice. In addition, by immunohistochemistry, we evaluated the expression of pro-survival marker Klotho, as well as markers of necroptosis (RIP1/3), inflammation (TNFα, IL1, NFkB), and defense against oxidative stress (SOD1, glutathione peroxidase, citrate synthase).

RESULTS

Diets with excess essential amino acids (EAAs) increased the expression of Klotho and enhanced anti-oxidative and anti-inflammatory responses, thereby promoting cell survival.

CONCLUSION

Our results further extend the current knowledge about the cardioprotective role of EAAs and provide a novel theoretical basis for their preemptive administration to cancer patients undergoing chemotherapy to alleviate the development and severity of Doxo-induced cardiomyopathy.

NSUN2 alleviates doxorubicin-induced myocardial injury through Nrf2-mediated antioxidant stress

Doxorubicin (DOX) is a commonly used antitumor drug, but its application has been limited because of its strong cardiac damage. This study aims to explore the role of NSUN2 in DOX-induced heart injury. C57BL/6J mice were intraperitoneally injected with 20 mg/Kg DOX to induce heart injury. After 3 days, the cardiac function, cardiac histopathology, myocardial apoptosis, and the expression level of NSUN2 were detected. In vitro, H9C2 cells were transfected with NSUN2 siRNA or overexpressed lentivirus and then treated with 500 ng/ml DOX. After 24 h, the changes in reactive oxygen species (ROS), apoptosis, and NSUN2 expression were detected. After DOX treatment, both in vitro and in vivo experiments showed that the cardiac function decreased, the number of apoptotic cells increased, and the expression level of NSUN2 increased. Interfering the expression of NSUN2 by siRNA promoted DOX-induced heart injury, while overexpression of NSUN2 could inhibit DOX-induced heart injury. Further study showed that NSUN2 promoted antioxidative stress by upregulating the Nrf2 protein level. In addition, NSUN2 overexpression could increase the half-life of Nrf2 mRNA. m5C RNA methylation immunoprecipitation (MeRIP) also showed that the level of Nrf2 m5C mRNA was significantly increased in NSUN2 overexpressed group when compared to the GFP group. NSUN2 enhances the expression of Nrf2 by promoting Nrf2 mRNA m5C modification and enhances its antioxidative stress effect to alleviate DOX-induced myocardial injury.

Piperlongumine as a Neuro-Protectant in Chemotherapy Induced Cognitive Impairment

Advances in the early diagnosis and treatment have led to increases in breast cancer survivorship. Survivors report cognitive impairment symptoms such as loss of concentration and learning and memory deficits which significantly reduce the patient's quality of life. Additional therapies are needed to prevent these side effects and, the precise mechanisms of action responsible are not fully elucidated. However, increasing evidence points toward the use of neuroprotective compounds with antioxidants and anti-inflammatory properties as tools for conserving learning and memory. Here, we examine the ability of piperlongumine (PL), an alkaloid known to have anti-inflammatory and antioxidant effects, to play a neuroprotective role in 16-week-old female C57BL/6J mice treated with a common breast cancer regimen of doxorubicin, cyclophosphamide, and docetaxel (TAC). During social memory testing, TAC-treated mice exhibited impairment, while TAC/PL co-treated mice did not exhibit measurable social memory deficits. Proteomics analysis showed ERK1/2 signaling is involved in TAC and TAC/PL co-treatment. Reduced Nrf2 mRNA expression was also observed. mRNA levels of Gria2 were increased in TAC treated mice and reduced in TAC/PL co-treated mice. In this study, PL protects against social memory impairment when co-administered with TAC via multifactorial mechanisms involving oxidative stress and synaptic plasticity.

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.

Role of oxidative stress in clofazimine-induced cardiac dysfunction in a zebrafish model

BACKGROUND

Clofazimine (CFZ), a riminophenazine, is now commonly used in the treatment of multidrug-resistant tuberculosis. However, its use may be potentially associated with cardiac dysfunction in some individuals. In this study, the zebrafish heart, by merit of its developmental and genetic characteristics being in homology with that of human, was chosen as an animal model for evaluation of such dysfunction.

METHODS

Morphological and physiological parameters were used to assess cardiac dysfunction. Transcriptome analysis was performed, followed by validation with real-time quantitative PCR, for delineation of the relevant genomics.

RESULTS

Exposure of 2 dpf zebrafish to 4 mg/L CFZ for 2 days, adversely affected cardiac functions including significant decreases in HR, SV, CO, and FS, with observable pathophysiological developments of pericardial effusion and blood accumulation in the heart, in comparison with the control group. In addition, genes which respond to xenobiotic stimulus, related to oxygen transport, glutathione metabolism and extracellular matrix -receptor interactions, were significantly enriched among the differentially up-regulated genes. Antioxidant response element motif was enriched in the 5000 base pair upstream regions of the differentially expressed genes. Co-administration of N-acetylcysteine was shown to protect zebrafish against the development of CFZ-induced cardiac dysfunction.

CONCLUSIONS

This study suggests an important role of oxidative stress as a major pathogenetic mechanism of riminophenazine-induced cardiac dysfunction.

Early Detection of Myocardial Damage: A Multimodality Approach

Cardiovascular diseases are possible complications of antineoplastic treatment and may lead to premature morbidity and mortality among cancer survivors. A symptom-based follow-up is ineffective, and there are growing evidences that early detection of myocardial damage in patients treated with antineoplastic drugs is the key point to prevent the occurrence of damage and improve the prognosis of these patients. Different techniques have been proposed to monitor cardiac function in oncologic patients such as cardiac imaging (echocardiography, nuclear imaging, and cardiac magnetic resonance) and biomarkers (troponin and natriuretic peptides). The European Association of Cardiovascular Imaging/American Society of Echocardiography consensus document encourages an integrated approach to early detect cardiotoxicity.

Cardamonin protects against doxorubicin-induced cardiotoxicity in mice by restraining oxidative stress and inflammation associated with Nrf2 signaling

The clinical application of doxorubicin (DOX) for cancer treatment is limited due to its cardiotoxicity. However, the basic pathophysiological molecular mechanisms underlying DOX-induced cardiomyopathy have not yet been completely clarified, and the disease-specific therapeutic strategies are lacking. The aim of the present study was to investigate the potential cardioprotective effect of cardamonin (CAR), a flavone found in Alpinia plant, on DOX-induced cardiotoxicity in a mouse model. At first, in DOX-treated mouse cardiomyocytes, CAR showed significantly cytoprotective effects through elevating nuclear factor erythroid-2 related factor 2 (Nrf2) signaling, and reducing the degradation of Nrf2. This process then improved the anti-oxidant system, as evidenced by the up-regulated expression levels of haem oxygenase-1 (HO1), NAD(P)H:quinone oxidoreductase 1 (NQO1), glutamate-cysteine ligase modifier subunit (GCLM), superoxide dismutase (SOD), glutathione (GSH) and catalase (CAT). In contrast, DOX-induced increases in malondialdehyde (MDA) and reactive oxygen species (ROS) were highly inhibited by CAR treatments. Additionally, DOX-induced apoptosis and inflammatory response in cardiomyocytes were diminished by CAR through reducing the Caspase-3 and nuclear factor-κB (NF-κB) signaling pathways, respectively. Then, in the DOX-induced animal model with cardiotoxicity, we confirmed that through improving Nrf2 signaling, CAR markedly suppressed oxidative stress, apoptosis and inflammatory response in hearts of mice, improving cardiac function eventually. Together, our findings demonstrated that CAR activated Nrf2-related cytoprotective system, and protected the heart from oxidative damage, apoptosis and inflammatory injury, suggesting that CAR might be a potential therapeutic strategy in the prevention of DOX-associated myocardiopathy.

Punicalagin protects H9c2 cardiomyocytes from doxorubicin-induced toxicity through activation of Nrf2/HO-1 signaling

Doxorubicin (DOX) is a wide-spectrum antitumor agent, but its clinical application is largely limited by its cardiotoxicity. Therefore, identification of effective agents against DOX-induced cardiotoxicity is of critical importance. The present study aimed to determine the beneficial role of punicalagin (PUN), a polyphenol isolated from pomegranate, in DOX-induced cardiotoxicity in vitro and explored the underlying mechanisms. H9c2 cardiomyocytes were pretreated with different concentrations (50, 100 and 200 μM) of PUN prior to DOX exposure. The results showed that PUN pretreatment significantly increased cell viability, inhibited lactate dehydrogenase (LDH) release and suppressed cell apoptosis induced by DOX. Additionally, PUN pretreatment attenuated the loss of mitochondrial membrane potential and cytochrome c release. Besides, PUN further enhanced the expression of nuclear Nrf2 and HO-1 in DOX-treated H9c2 cells, and the aforementioned beneficial effects of PUN were partially abolished by small interfering RNA (siRNA)-mediated Nrf2 knockdown. Hence, our findings clearly revealed that PUN might be a promising agent for alleviating the cardiotoxicity of DOX, and Nrf2/HO-1 signaling might serve a critical role during this process.

Advances in phytochemical delivery systems for improved anticancer activity

Natural compounds have significant anticancer pharmacological activities, but often suffer from low bioavailability and selectivity that limit therapeutic use. The present work critically analyzes the latest advances on drug delivery systems designed to enhance pharmacokinetics, targeting, cellular uptake and efficacy of anticancer phytoconstituents. Various phytochemicals, including flavonoids, resveratrol, celastrol, curcumin, berberine and camptothecins, carried by liposomes, nanoparticles, nanoemulsions and films showed promising results. Strategies to avoid drug metabolism, overcome physiological barriers and achieve higher concentration at cancer sites through skin, buccal, nasal, vaginal, pulmonary and colon targeted delivery are presented. Current limitations, challenges and future research directions are also discussed.

Possible roles of genetic variations in chemotherapy related cardiotoxicity in pediatric acute lymphoblastic leukemia and osteosarcoma

Background

The treatment of acute lymphoblastic leukemia (ALL) and osteosarcoma (OSC) is very effective: the vast majority of patients recover and survive for decades. However, they still need to face serious adverse effects of chemotherapy. One of these is cardiotoxicity which may lead to progressive heart failure in the long term. Cardiotoxicity is contributed mainly to the use of anthracyclines and might have genetic risk factors. Our goal was to test the association between left ventricular function and genetic variations of candidate genes.

Methods

Echocardiography data from medical records of 622 pediatric ALL and 39 OSC patients were collected from the period 1989–2015. Fractional shortening (FS) and ejection fraction (EF) were determined, 70 single nucleotide polymorphisms (SNPs) in 26 genes were genotyped. Multivariate logistic regression and multi-adjusted general linear model were performed to investigate the influence of genetic polymorphisms on the left ventricular parameters. Bayesian network based Bayesian multilevel analysis of relevance (BN-BMLA) method was applied to test for the potential interaction of the studied cofactors and SNPs.

Results

Our results indicate that variations in ABCC2, CYP3A5, NQO1, SLC22A6 and SLC28A3 genes might influence the left ventricular parameters. CYP3A5 rs4646450 TT was 17% among ALL cases with FS lower than 28, and 3% in ALL patients without pathological FS (p = 5.60E-03; OR = 6.94 (1.76–27.39)). SLC28A3 rs7853758 AA was 12% in ALL cases population, while only 1% among controls (p = 6.50E-03; OR = 11.56 (1.98–67.45)). Patients with ABCC2 rs3740066 GG genotype had lower FS during the acute phase of therapy and 5–10 years after treatment (p = 7.38E-03, p = 7.11E-04, respectively). NQO1 rs1043470 rare T allele was associated with lower left ventricular function in the acute phase and 5–10 years after the diagnosis (p = 4.28E-03 and 5.82E-03, respectively), and SLC22A6 gene rs6591722 AA genotype was associated with lower mean FS (p = 1.71E-03), 5–10 years after the diagnosis.

Conclusions

Genetic variants in transporters and metabolic enzymes might modulate the individual risk to cardiac toxicity after chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4629-6) contains supplementary material, which is available to authorized users.

Klotho Improves Cardiac Function by Suppressing Reactive Oxygen Species (ROS) Mediated Apoptosis by Modulating Mapks/Nrf2 Signaling in Doxorubicin-Induced Cardiotoxicity

Background

Anthracyclines-induced cardiotoxicity has become one of the major restrictions of their clinical applications. Klotho showed cardioprotective effects. This study aimed to investigate the effects and possible mechanisms of klotho on doxorubicin (DOX)-induced cardiotoxicity.

Material/Methods

Rats and isolated myocytes were exposed to DOX and treated with exogenous klotho. Specific inhibitors and siRNAs silencing MAPKs were also used to treat the animals and/or myocytes. An invasive hemodynamic method was used to determine cardiac functions. Intracellular ROS generation was evaluated by DHE staining. Western blotting was used to determine the phosphorylation levels of JNK, ERK, and p38 MAPKs in plasma extracts and Nrf2 in nuclear extracts. Nuclear translocation of Nrf2 in myocytes was evaluated by immunohistochemistry. Cell apoptosis was evaluated by TUNEL assay and flow cytometry.

Results

Klotho treatment improved DOX-induced cardiac dysfunction in rats. The DOX-induced ROS accumulation and cardiac apoptosis were attenuated by klotho. Impaired phosphorylations of MAPKs, Nrf2 translocation and expression levels of HO1 and Prx1 were also attenuated by klotho treatment. However, the anti-oxidant and anti-apoptotic effects of klotho on DOX-exposed myocardium and myocytes were impaired by both specific inhibitors and siRNAs against MAPKs. Moreover, the recovery effects of klotho on phosphorylations of MAPKs, Nrf2 translocation and expression levels of HO1 and Prx1 were also impaired by specific inhibitors and siRNAs against MAPKs.

Conclusions

By recovering the activation of MAPKs signaling, klotho improved cardiac function loss which was triggered by DOX-induced ROS mediated cardiac apoptosis.

Correlation between the potency of flavonoids for cytochrome c reduction and inhibition of cardiolipin-induced peroxidase activity

There are large differences between flavonoids to protect against apoptosis, a process in which cytochrome c (Cyt c) plays a key role. In this work, we show that 7 of 13 flavonoids studied have a capacity to reduce Cyt c similar or higher than ascorbate, the flavonols quercetin, kaempferol and myricetin, flavanol epigallocatechin-gallate, anthocyanidins cyanidin and malvidin, and the flavone luteolin. In contrast, the kaempferol 3(O)- and 3,4'(O)-methylated forms, the flavanone naringenin, and also apigenin and chrysin, had a negligible reducing capacity. Equilibrium dialysis and quenching of 1,6-diphenyl-1,3,5-hexatriene fluorescence experiments showed that flavonoids did not interfere with Cyt c binding to cardiolipin (CL)/phosphatidylcholine (PC) vesicles. However, the CL-induced loss of Cyt c Soret band intensity was largely attenuated by flavonoids, pointing out a stabilizing action against Cyt c unfolding in the complex. Moreover, flavonoids that behave as Cyt c reductants also inhibited the pro-apoptotic CL-induced peroxidase activity of Cyt c, indicating that modulation of Cyt c signaling are probable mechanisms behind the protective biological activities of flavonoids. © 2016 BioFactors, 43(3):451-468, 2017.

Effect of combined medicated thread moxibustion plus needle picking therapy of Zhuang nationality medicine on antioxidant levels in a rat model of sciatica

OBJECTIVE

To investigate the effect and underlying mechanisms of combined medicated thread moxibustion therapy plus needle picking therapy of Zhuang nationality medicine on antioxidant levels in a rat model of sciatica.

METHODS

One hundred Wistar rats, of specific pathogen free level, were randomly divided into five groups: normal control group, model group, medicated thread moxibustion group, needle picking group, and combination group. Each group contained 20 rats. In the model, medicated thread moxibustion, needle picking, and combination groups, sciatica models were established through chronic constriction injury of the sciatic nerve. After the model was established, the rats in the medicated thread moxibustion, needle picking, and combination groups were given the corresponding therapies for 21 days. The control and model groups received no treatment. Reactive oxygen species, superoxide dismutase, malondialdehyde, and total antioxidant capacity changes were determined. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit NADPH oxidases 4 (NOX4) mRNA expression and the morphology of cells were observed to detect apoptosis of gamma- aminobutyric acid ergic (GABAergic) neurons.

RESULTS

Compared with control group, reactive oxygen species and malondialdehyde levels rose significantly in the model group (P < 0.01), while superoxide dismutase and total antioxidant capacity levels were lowered (P < 0.05). Compared with the model group, reactive oxygen species and malondialdehyde decreased in the needle picking group (P < 0.05), while superoxide dismutase levels were increased (P < 0.05); reactive oxygen species and malondialdehyde significantly decreased in the combination group (P < 0.01). In addition, the model group had higher NOX4 mRNA expression than that of the control group (P < 0.05), and the combination group had lower expression levels than that of the model group (P < 0.05). Apoptosis of GABAergic neurons was observed in the model group, and was attenuated after combined therapy.

CONCLUSION

The medicated thread moxibustion therapy plus needle picking therapy of Zhuang nationality medicine can prevent oxidative damage in the rat model of sciatica via down-regulating NOX4 expression, improving antioxidant capacity, and inhibiting the oxidative damage pathway of GABAergic neurons.

Role of biomarkers in monitoring antiblastic cardiotoxicity

Early detection of anticancer drug-induced cardiotoxicity (CTX) has been evaluated by most international scientific cardiology and oncology societies. High expectations have been placed on the use of specific biomarkers. In recent years, conventional biomarkers and molecules of more recent interest have been tested and compared in the context of anticancer drug-related CTX. Encouraging results were obtained from studies on molecules of myocardial damage, such as troponin and markers of myocardial wall stress, including circulating natriuretic peptides, as well as from the assessment of the products of inflammation or circulating levels of free radicals. However, clear guidelines on their sensitivity, specificity, and accuracy are not yet available, and many challenges, such as the optimal time of assessing, optimal schedule for evaluation, optimal cut-off point for positivity with the highest level of specificity, and optimal comparability of different assays for the measurements, remain unresolved. Given the importance of having a reliable and accurate tool for monitoring anticancer drug-induced CTX, this review will focus on the available data on the most effective and widely used biomarkers and the studies that are currently underway that aim to identify the effectiveness of new approaches in this therapeutic setting.

The interplay between genetic background and sexual dimorphism of doxorubicin-induced cardiotoxicity

Background

Doxorubicin (DOX) is a very effective anticancer medication that is commonly used to treat hematological malignancies and solid tumors. Nevertheless, DOX is known to have cardiotoxic effects that may lead to cardiac dysfunction and failure. In experimental studies, female animals have been shown to be protected against DOX-induced cardiotoxicity; however, the evidence of this sexual dimorphism is inconclusive in clinical studies. Therefore, we sought to investigate whether genetic background could influence the sexual dimorphism of DOX-induced cardiotoxicity.

Methods

Male and female Wistar Kyoto (WKY) and Spontaneous Hypertensive Heart Failure (SHHF) rats were used. DOX was administered in eight doses of 2 mg/kg/week and the rats were followed for an additional 12 weeks. Cardiac function was assessed by trans-thoracic echocardiography, systolic blood pressure was measured by the tail cuff method, and heart and kidney tissues were collected for histopathology.

Results

Female sex protected against DOX-induced weight loss and increase in blood pressure in the WKY rats, whereas it protected against DOX-induced cardiac dysfunction and the elevation of cardiac troponin in SHHF rats. In both strains, female sex was protective against DOX-induced nephrotoxicity. There was a strong correlation between DOX-induced renal pathology and DOX-induced cardiac dysfunction.

Conclusions

This study highlights the importance of studying the interaction between sex and genetic background to determine the risk of DOX-induced cardiotoxicity. In addition, our findings suggest that DOX-induced nephrotoxicity may play a role in DOX-induced cardiac dysfunction in rodent models.

Role of Drug Metabolism in the Cytotoxicity and Clinical Efficacy of Anthracyclines

Many clinical studies involving anti-tumor agents neglect to consider how these agents are metabolized within the host and whether the creation of specific metabolites alters drug therapeutic properties or toxic side effects. However, this is not the case for the anthracycline class of chemotherapy drugs. This review describes the various enzymes involved in the one electron (semi-quinone) or two electron (hydroxylation) reduction of anthracyclines, or in their reductive deglycosidation into deoxyaglycones. The effects of these reductions on drug antitumor efficacy and toxic side effects are also discussed. Current evidence suggests that the one electron reduction of anthracyclines augments both their tumor toxicity and their toxicity towards the host, in particular their cardiotoxicity. In contrast, the two electron reduction (hydroxylation) of anthracyclines strongly reduces their ability to kill tumor cells, while augmenting cardiotoxicity through their accumulation within cardiomyocytes and their direct effects on excitation/contraction coupling within the myocytes. The reductive deglycosidation of anthracyclines appears to inactivate the drug and only occurs under rare, anaerobic conditions. This knowledge has resulted in the identification of important new approaches to improve the therapeutic index of anthracyclines, in particular by inhibiting their cardiotoxicity. The true utility of these approaches in the management of cancer patients undergoing anthracycline-based chemotherapy remains unclear, although one such agent (the iron chelator dexrazoxane) has recently been approved for clinical use.