Mechanism of doxorubicin-induced inhibition of sarcoplasmic reticulum Ca(2+)-ATPase gene transcription

Cell-Permeable Microprotein from Panax Ginseng Protects Against Doxorubicin-Induced Oxidative Stress and Cardiotoxicity

(1) Background: Doxorubicin (DOX) is a frontline chemotherapeutic, but its side-effects from oxidative stress, leading to cardiotoxicity, pose significant challenges to its clinical use. We recently discovered a novel family of proteolysis-resistant, cystine-dense, and cell-penetrating microproteins from Panax ginseng that we term ginsentides. Ginsentides, such as the 31-residue TP1, coordinate multiple biological systems to prevent vascular dysfunction and endoplasmic reticulum stress induced by internal and external stressors. (2) Methods: We assessed the protective effects of ginsentide TP1 on DOX-induced cardiotoxicity using both in vitro functional studies on H9c2 cardiomyocytes and in vivo animal models by zebrafish and ICR mouse models. In these models, we examined oxidative stress, apoptosis, intracellular calcium levels, mitochondrial function, inflammatory responses, and cardiac function. (3) Results: We show that ginsentide TP1 protects against DOX-induced cytotoxicity in the mitochondria-rich H9c2 cardiomyocytes and reduces myocardial injury in zebrafish and mice by mitigating oxidative stress, inflammation, calcium, and mitochondrial dysfunction, as well as apoptosis-mediated cell death. Importantly, TP1 preserves cellular homeostasis without compromising the anticancer potency of DOX in breast cancer cells. (4) Conclusions: our findings highlight a specific antioxidative function of ginsentide TP1 in managing DOX-induced cardiotoxicity during cancer treatment and provide a promising lead for developing cardioprotective peptides and microproteins against oxidative stress.

Early detection of anthracycline-induced cardiotoxicity

Although anthracyclines are important anticancer agents, their use is limited due to various adverse effects, particularly cardiac toxicity. Mechanisms underlying anthracycline-induced cardiotoxicity (AIC) are complex. Given the irreplaceable role of anthracyclines in treatment of malignancies and other serious diseases, early monitoring of AIC is paramount. In recent years, multiple studies have investigated various biomarkers for early detection of AIC. Currently, the two most common are cardiac troponin and B-type natriuretic peptide. In addition, a range of other molecules, including RNAs, myeloperoxidase (MPO), C-reactive protein (CRP), various genes, and others, also play roles in AIC prediction. Unfortunately, current research indicates a need to validate their sensitivity and specificity of these biomarkers especially in large study populations. In this review, we summarize the mechanisms and potential biomarkers of AIC, although some remain preliminary.

Alterations in the gut microbiome and metabolism with doxorubicin-induced heart failure severity

Objective

This study aimed to explore the changes in gut microbiota and its metabolites in different pathophysiological stages of doxorubicin (DOX)-induced heart failure (DIHF) and the relationship between gut microbiota and metabolites in various degrees of DIHF.

Materials and methods

C57BL/6 J mice were injected intraperitoneally with 5 mg/kg of DOX once a week for 5 consecutive weeks. At different times after injection, the cardiac function and histopathological analysis was conducted, the serum levels of creatine kinase (CK), CK-MB, lactic dehydrogenase, and cardiac troponin T were determined. 16S rRNA gene sequencing of feces and the nontargeted metabolomics analysis of serum were performed. Multi-omics analyses were used to explore the correlation between gut microbiota and serum metabolites.

Results

The results showed that DOX caused cardiac contractile dysfunction and left ventricular (LV) dilation. The levels of myocardial enzymes significantly increase in 3 and 5 weeks after DOX injection. DOX-treated mice showed significant differences in the composition and abundance of gut microorganisms, and the levels of serum metabolites at different times of treatment. Multi-omics analyses showed that intestinal bacteria were significantly correlated with the differential metabolites. Some bacteria and metabolites can be used as biomarkers of DIHF (AUC > 0.8). KEGG analyses showed the involvement of different metabolic pathways in various degrees of DIHF.

Conclusion

Marked differences were found in the composition and abundance of gut microorganisms, the levels of serum metabolites and metabolic pathways in different degrees of DIHF. The intestinal bacteria were significantly correlated with differential metabolites in different degrees of DIHF. The gut microbiota may serve as new targets for the treatment of DIHF.

MiR-24-3p modulates cardiac function in doxorubicin -induced heart failure via the Sp1/PI3K signaling pathway

PURPOSE

The goal of this research was to explore the role of miR-24-3p in heart failure (HF), with a focus on its impact on the specificity protein 1 (Sp1)/phosphoinositide 3-kinase (PI3K) pathway.

METHODS

HF rat and HF cell models were established using doxorubicin(Dox). Cardiac function was assessed through echocardiography, while histological changes were observed via hematoxylin-eosin (HE) staining. To further investigate the underlying mechanisms, HF cell models were treated with either an Sp1 inhibitor or a PI3K inhibitor. Additionally, models with miR-24-3p overexpression or silencing were constructed. N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were determined by ELISA. Cell apoptosis was evaluated using TUNEL staining, and lactate dehydrogenase (LDH) levels were measured by colorimetry. Reactive oxygen species (ROS) production was analyzed using flow cytometry. Related gene and protein expressions were assessed via qRT-PCR and Western blotting. Finally, the relationship between miR-24-3p and Sp1 was confirmed through dual-luciferase assays.

RESULTS

Dox treatment increased the left ventricular internal diameter (LVIDd) while decreasing ejection fraction (EF) and fractional shortening (FS), leading to disorganized cardiomyocyte arrangement, cellular edema, and necrosis in rats. In HF rats, NT-proBNP, Caspase-3, and miR-24-3p expression levels were elevated, whereas Sp1 and PI3K mRNA and protein expression levels were decreased. Similarly, Dox-induced damage in H9c2 cardiomyocytes resulted in increased NT-proBNP, apoptosis, Caspase-3, LDH, ROS, and miR-24-3p expression, along with decreased Sp1 and PI3K expression. Treatment with either Sp1 or PI3K inhibitors exacerbated the Dox-induced cardiomyocyte damage, further elevating NT-proBNP, apoptosis, Caspase-3, LDH, ROS, and miR-24-3p expression levels. Notably, Sp1 inhibition reduced PI3K expression, and PI3K inhibition, in turn, suppressed Sp1 expression. Overexpression of miR-24-3p worsened Dox-induced cardiomyocyte damage, characterized by increased NT-proBNP, apoptosis, Caspase-3, LDH, and ROS expression, alongside reduced Sp1 and PI3K expression. In contrast, silencing miR-24-3p mitigated these detrimental effects and increased Sp1 and PI3K expression. Dual-luciferase assays confirmed that miR-24-3p directly targets Sp1.

CONCLUSION

Dox induces cardiomyocyte damage, impairs cardiac function, and promotes cardiomyocyte apoptosis and oxidative stress. Silencing miR-24-3p offers a protective effect by activating the Sp1/PI3K signaling pathway in heart failure.

The Abl1 tyrosine kinase is a key player in doxorubicin-induced cardiomyopathy and its p53/p73 cell death mediated signaling differs in atrial and ventricular cardiomyocytes

BACKGROUND

Doxorubicin is an important anticancer drug, however, elicits dose-dependently cardiomyopathy. Given its mode of action, i.e. topoisomerase inhibition and DNA damage, we investigated genetic events associated with cardiomyopathy and searched for mechanism-based possibilities to alleviate cardiotoxicity. We treated rats at clinically relevant doses of doxorubicin. Histopathology and transmission electron microscopy (TEM) defined cardiac lesions, and transcriptomics unveiled cardiomyopathy-associated gene regulations. Genomic-footprints revealed critical components of Abl1-p53-signaling, and EMSA-assays evidenced Abl1 DNA-binding activity. Gene reporter assays confirmed Abl1 activity on p53-targets while immunohistochemistry/immunofluorescence microscopy demonstrated Abl1, p53&p73 signaling.

RESULTS

Doxorubicin treatment caused dose-dependently toxic cardiomyopathy, and TEM evidenced damaged mitochondria and myofibrillar disarray. Surviving cardiomyocytes repressed Parkin-1 and Bnip3-mediated mitophagy, stimulated dynamin-1-like dependent mitochondrial fission and induced anti-apoptotic Bag1 signaling. Thus, we observed induced mitochondrial biogenesis. Transcriptomics discovered heterogeneity in cellular responses with minimal overlap between treatments, and the data are highly suggestive for distinct cardiomyocyte (sub)populations which differed in their resilience and reparative capacity. Genome-wide footprints revealed Abl1 and p53 enriched binding sites in doxorubicin-regulated genes, and we confirmed Abl1 DNA-binding activity in EMSA-assays. Extraordinarily, Abl1 signaling differed in the heart with highly significant regulations of Abl1, p53 and p73 in atrial cardiomyocytes. Conversely, in ventricular cardiomyocytes, Abl1 solely-modulated p53-signaling that was BAX transcription-independent. Gene reporter assays established Abl1 cofactor activity for the p53-reporter PG13-luc, and ectopic Abl1 expression stimulated p53-mediated apoptosis.

CONCLUSIONS

The tyrosine kinase Abl1 is of critical importance in doxorubicin induced cardiomyopathy, and we propose its inhibition as means to diminish risk of cardiotoxicity.

Doxorubicin conjugates: a practical approach for its cardiotoxicity alleviation

INTRODUCTION

Doxorubicin (DOX) emerges as a cornerstone in the arsenal of potent chemotherapeutic agents. Yet, the clinical deployment of DOX is tarnished by its proclivity to induce severe cardiotoxic effects, culminating in heart failure and other consequential morbidities. In response, a panoply of strategies has undergone rigorous exploration over recent decades, all aimed at attenuating DOX's cardiotoxic impact. The advent of encapsulating DOX within lipidic or polymeric nanocarriers has yielded a dual triumph, augmenting DOX's therapeutic efficacy while mitigating its deleterious side effects.

AREAS COVERED

Recent strides have spotlighted the emergence of DOX conjugates as particularly auspicious avenues for ameliorating DOX-induced cardiotoxicity. These conjugates entail the fusion of DOX through physical or chemical bonds with diminutive natural or synthetic moieties, polymers, biomolecules, and nanoparticles. This spectrum encompasses interventions that impinge upon DOX's cardiotoxic mechanism, modulate cellular uptake and localization, confer antioxidative properties, or refine cellular targeting.

EXPERT OPINION

The endorsement of DOX conjugates as a compelling stratagem to mitigate DOX-induced cardiotoxicity resounds from this exegesis, amplifying safety margins and the therapeutic profile of this venerated chemotherapeutic agent. Within this ambit, DOX conjugates stand as a beacon of promise in the perpetual pursuit of refining chemotherapy-induced cardiac compromise.

Drug-induced atrial fibrillation. A narrative review of a forgotten adverse effect

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an increased morbidity and mortality. There is clinical evidence that an increasing number of cardiovascular and non-cardiovascular drugs, mainly anticancer drugs, can induce AF either in patients with or without pre-existing cardiac disorders, but drug-induced AF (DIAF) has not received the attention that it might deserve. In many cases DIAF is asymptomatic and paroxysmal and patients recover sinus rhythm spontaneously, but sometimes, DIAF persists, and it is necessary to perform a cardioversion. Furthermore, DIAF is not mentioned in clinical guidelines on the treatment of AF. The risk of DIAF increases in elderly and in patients treated with polypharmacy and with risk factors and comorbidities that commonly coexist with AF. This is the case of cancer patients. Under these circumstances ascribing causality of DIAF to a given drug often represents a clinical challenge. We review the incidence, the pathophysiological mechanisms, risk factors, clinical relevance, and treatment of DIAF. Because of the limited information presently available, further research is needed to obtain a deeper insight into DIAF. Meanwhile, it is important that clinicians are aware of the problem that DIAF represents, recognize which drugs may cause DIAF, and consider the possibility that a drug may be responsible for a new-onset AF episode.

Empagliflozin treatment of cardiotoxicity: A comprehensive review of clinical, immunobiological, neuroimmune, and therapeutic implications

Cancer and cardiovascular disorders are known as the two main leading causes of mortality worldwide. Cardiotoxicity is a critical and common adverse effect of cancer-related chemotherapy. Chemotherapy-induced cardiotoxicity has been associated with various cancer treatments, such as anthracyclines, immune checkpoint inhibitors, and kinase inhibitors. Different methods have been reported for the management of chemotherapy-induced cardiotoxicity. In this regard, sodium-glucose cotransporter-2 inhibitors (SGLT2i), a class of antidiabetic agents, have recently been applied to manage heart failure patients. Further, SGLT2i drugs such as EMPA exert protective cardiac and systemic effects. Moreover, it can reduce inflammation through the mediation of major inflammatory components, such as Nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasomes, Adenosine 5'-monophosphate-activated protein kinase (AMPK), and c-Jun N-terminal kinase (JNK) pathways, Signal transducer and activator of transcription (STAT), and overall decreasing transcription of proinflammatory cytokines. The clinical outcome of EMPA administration is related to improving cardiovascular risk factors, including body weight, lipid profile, blood pressure, and arterial stiffness. Intriguingly, SGLT2 suppressors can regulate microglia-driven hyperinflammation affecting neurological and cardiovascular disorders. In this review, we discuss the protective effects of EMPA in chemotherapy-induced cardiotoxicity from molecular, immunological, and neuroimmunological aspects to preclinical and clinical outcomes.

Poly (ADP-ribose) polymerase pathway inhibitor (Olaparib) upregulates SERCA2a expression and attenuates doxorubicin-induced cardiomyopathy in mice

The cardiotoxicity induced by doxorubicin is dose-dependent. The present study tested the potential cardioprotective effect of Poly ADP Ribose Polymerase (PARP) pathway inhibitor "olaparib" in a mouse model of doxorubicin-induced cardiomyopathy (DOX-CM). Seventy-two male BALB/c mice were randomized into six equal groups; control, DOX-CM, dexrazoxane-treated, and three olaparib-treated groups (5, 10, and 50 mg/kg/day). Cardiomyopathy was assessed by heart weight/Tibial length (HW/TL) ratio, cardiac fibrosis, oxidative stress, and electron microscope. Myocardial expression of SERCA2a mRNA and cleaved PARP-1 protein were also assessed. Similar to dexrazoxane, olaparib (10 mg/kg/day) significantly ameliorated oxidative stress, and preserved cardiac structure. It also suppressed myocardial PARP-1 protein expression and boosted SERCA2a mRNA expression. Olaparib (5 or 50 mg/kg/day) failed to show comparable effects. The current study detected the cardioprotective effect of olaparib at a dosage of 10 mg/kg/day. Also, the present study discovered a new cardioprotective mechanism of dexrazoxane by targeting PARP-1 in the heart.

Hydrogen sulfide alleviates mitochondrial damage and ferroptosis by regulating OPA3-NFS1 axis in doxorubicin-induced cardiotoxicity

Ferroptosis is a major cause of cardiotoxicity induced by doxorubicin (DOX). Previous studies have shown that hydrogen sulfide (H₂S) inhibits ferroptosis in cardiomyocytes and myoblasts, but the underlying mechanism has not been fully elucidated. In this study, we investigated the role of H₂S in protecting against DOX-induced cardiotoxicity both in vivo and in vitro, and elucidated the potential mechanisms involved. We found that DOX downregulated the expression of glutathione peroxidase 4 (GPX4) and NFS1, and upregulated the expression of acyl-coenzyme A synthetase long-chain family member 4 (ACSL4) expression level, resulting in increased lipid peroxidation and ferroptosis. Additionally, DOX inhibited MFN2 expression and increased DRP1 and FIS1 expression, leading to abnormal mitochondrial structure and function. In contrast, exogenous H₂S inhibited DOX-induced ferroptosis by restoring GPX4 and NFS1 expression, and reducing lipid peroxidation in H9C2 cells. This effect was similar to that of the ferroptosis antagonist ferrostatin-1 (Fer-1) in protecting against DOX-induced cardiotoxicity. We further demonstrated that the protective effect of H₂S was mediated by the key mitochondrial membrane protein optic atrophy 3 (OPA3), which was downregulated by DOX and restored by exogenous H₂S. Overexpression of OPA3 alleviated DOX-induced mitochondrial dysfunction and ferroptosis both in vivo and in vitro. Mechanistically, NFS1 has an inhibitory effect on ferroptosis, and NFS1 deficiency increases the susceptibility of cardiomyocytes to ferroptosis. OPA3 is involved in the regulation of ferroptosis by interacting with NFS1. Post-translationally, DOX promoted OPA3 ubiquitination, while exogenous H₂S antagonized OPA3 ubiquitination by promoting OPA3 s-sulfhydration. In summary, our findings suggested that H₂S protects against DOX-induced cardiotoxicity by inhibiting ferroptosis via targeting the OPA3-NFS1 axis. This provides a potential therapeutic strategy for the treatment of DOX-induced cardiotoxicity.

18F-FDG PET/MRI Imaging in a Preclinical Rat Model of Cardiorenal Syndrome-An Exploratory Study

Cardiorenal syndrome (CRS) denotes the bidirectional interaction of chronic kidney disease and heart failure with an adverse prognosis but with a limited understanding of its pathogenesis. This study correlates biochemical blood markers, histopathological and immunohistochemistry features, and 2-deoxy-2-fluoro-D-glucose positron emission tomography (¹⁸F-FDG PET) metabolic data in low-dose doxorubicin-induced heart failure, cardiorenal syndrome, and renocardiac syndrome induced on Wistar male rats. To our knowledge, this is the first study that investigates the underlying mechanisms for CRS progression in rats using ¹⁸F-FDG PET. Clinical, metabolic cage monitoring, biochemistry, histopathology, and immunohistochemistry combined with PET/MRI (magnetic resonance imaging) data acquisition at distinct points in the disease progression were employed for this study in order to elucidate the available evidence of organ crosstalk between the heart and kidneys. In our CRS model, we found that chronic treatment with low-dose doxorubicin followed by acute 5/6 nephrectomy incurred the highest mortality among the study groups, while the model for renocardiac syndrome resulted in moderate-to-high mortality. ¹⁸F-FDG PET imaging evidenced the doxorubicin cardiotoxicity with vascular alterations, normal kidney development damage, and impaired function. Given the fact that standard clinical markers were insensitive to early renal injury, we believe that the decreasing values of the ¹⁸F-FDG PET-derived renal marker across the groups and, compared with their age-matched controls, along with the uniform distribution seen in healthy developing rats, could have a potential diagnostic and prognostic yield in cardiorenal syndrome.

Exploration of the amino acid metabolic signature in anthracycline-induced cardiotoxicity using an optimized targeted metabolomics approach based on UPLC-MS/MS

Although anthracyclines improve the long-term survival rate of patients with cancer, severe and irreversible myocardial damage limits their clinical application. Amino acid (AA) metabolism in cardiomyocytes can be altered under pathological conditions. Therefore, exploring the AA metabolic signature in anthracycline-induced cardiotoxicity (AIC) is important for identifying novel mechanisms. We established mouse and cellular models of Adriamycin (ADR)-induced cardiac injury. We observed a decreased expression of troponins I (cTnI) after ADR treatment and ADR accelerated the degradation of cTnI, implying that AA metabolism could be altered in AIC. Using a targeted AA metabolomics approach based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), the AA metabolic signatures in the sera of AIC mice and supernatant samples of ADR-treated H9c2 cardiomyocytes were analyzed. The levels of 14 AA metabolites were altered in ADR-treated mice (p < 0.05). Via bioinformatics analysis, we identified nine differential AA metabolites in mice and five differential AA metabolites in ADR-treated H9c2 cardiomyocytes. Three AAs with increased levels (L-glutamate, L-serine, and L-tyrosine) overlapped in the two models, suggesting a possible mechanism of AA metabolic impairment during AIC. The metabolic pathways perturbed by AIC involved aminoacyl-tRNA biosynthesis and alanine, aspartate, and glutamate metabolism. Our data suggests that ADR perturbed AA metabolism in AIC models. Moreover, the targeted AA metabolomics approach based on UPLC-MS/MS can be a unique platform to provide new clues for the prevention and treatment of AIC.

Statins Protect Against Early Stages of Doxorubicin-induced Cardiotoxicity Through the Regulation of Akt Signaling and SERCA2

Background

Doxorubicin-induced cardiomyopathy (DICM) is one of the complications that can limit treatment for a significant number of cancer patients. In animal models, the administration of statins can prevent the development of DICM. Therefore, the use of statins with anthracyclines potentially could enable cancer patients to complete their chemotherapy without added cardiotoxicity. The precise mechanism mediating the cardioprotection is not well understood. The purpose of this study is to determine the molecular mechanism by which rosuvastatin confers cardioprotection in a mouse model of DICM.

Methods

Rosuvastatin was intraperitoneally administered into adult male mice at 100 μg/kg daily for 7 days, followed by a single intraperitoneal doxorubicin injection at 10 mg/kg. Animals continued to receive rosuvastatin daily for an additional 14 days. Cardiac function was assessed by echocardiography. Optical calcium mapping was performed on retrograde Langendorff perfused isolated hearts. Ventricular tissue samples were analyzed by immunofluorescence microscopy, Western blotting, and quantitative polymerase chain reaction.

Results

Exposure to doxorubicin resulted in significantly reduced fractional shortening (27.4% ± 1.11% vs 40% ± 5.8% in controls; P < 0.001) and re-expression of the fetal gene program. However, we found no evidence of maladaptive cardiac hypertrophy or adverse ventricular remodeling in mice exposed to this dose of doxorubicin. In contrast, rosuvastatin-doxorubicin-treated mice maintained their cardiac function (39% ± 1.26%; P < 0.001). Mechanistically, the effect of rosuvastatin was associated with activation of Akt and phosphorylation of phospholamban with preserved sarcoplasmic/endoplasmic reticulum Ca²⁺ transporting 2 (SERCA2)-mediated Ca²⁺ reuptake. These effects occurred independently of perturbations in ryanodine receptor 2 function.

Conclusions

Rosuvastatin counteracts the cardiotoxic effects of doxorubicin by directly targeting sarcoplasmic calcium cycling.

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

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

MicroRNA-194-5p Attenuates Doxorubicin-Induced Cardiomyocyte Apoptosis and Endoplasmic Reticulum Stress by Targeting P21-Activated Kinase 2

Objective

Many studies have reported that microRNAs (miRs) are involved in the regulation of doxorubicin (DOX)-induced cardiotoxicity. MiR-194-5p has been reported significantly upregulated in patients with myocardial infarction; however, its role in myocardial diseases is still unclear. Various stimuluses can trigger the endoplasmic reticulum (ER) stress and it may activate the apoptosis signals eventually. This study aims to explore the regulatory role of miR-194-5p in DOX-induced ER stress and cardiomyocyte apoptosis.

Methods

H9c2 was treated with 2 μM DOX to induce apoptosis, which is to stimulate the DOX-induced cardiotoxicity model. The expression of miR-194-5p was detected by quantitative real-time PCR (qRT-PCR); the interaction between miR-194-5p and P21-activated kinase 2 (PAK2) was tested by dual luciferase reporter assay; terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and caspase-3/7 activity were used to assess apoptosis; trypan blue staining was applied to measure cell death; Western blotting was performed to detect protein expressions; and ER-related factors splicing X-box binding protein 1 (XBP1s) was detected by polyacrylamide gel electrophoresis and immunofluorescence to verify the activation of ER stress.

Results

MiR-194-5p was upregulated in cardiomyocytes and mouse heart tissue with DOX treatment, while the protein level of PAK2 was downregulated. PAK2 was predicted as the target of miR-194-5p; hence, dual luciferase reporter assay indicated that miR-194-5p directly interacted with PAK2 and inhibited its expression. TUNEL assay, caspase-3/7 activity test, and trypan blue stain results showed that either inhibition of miR-194-5p or overexpression of PAK2 reduced DOX-induced cardiomyocyte apoptosis. Silencing of miR-194-5p also improved DOX-induced cardiac dysfunction. In addition, DOX could induce ER stress in H9c2, which led to XBP1 and caspase-12 activation. The expression level of XBP1s with DOX treatment increased first then decreased. Overexpression of XBP1s suppressed DOX-induced caspase-3/7 activity elevation as well as the expression of cleaved caspase-12, which protected cardiomyocyte from apoptosis. Additionally, the activation of XBP1s was regulated by miR-194-5p and PAK2.

Conclusion

Our findings revealed that silencing miR-194-5p could alleviate DOX-induced cardiotoxicity via PAK2 and XBP1s in vitro and in vivo. Thus, the novel miR-194-5p/PAK2/XBP1s axis might be the potential prevention/treatment targets for cancer patients receiving DOX treatment.

Calcium dysregulation in heart diseases: Targeting calcium channels to achieve a correct calcium homeostasis

Intracellular calcium signaling is a universal language source shared by the most part of biological entities inside cells that, all together, give rise to physiological and functional anatomical units, the organ. Although preferentially recognized as signaling between cell life and death processes, in the heart it assumes additional relevance considered the importance of calcium cycling coupled to ATP consumption in excitation-contraction coupling. The concerted action of a plethora of exchangers, channels and pumps inward and outward calcium fluxes where needed, to convert energy and electric impulses in muscle contraction. All this without realizing it, thousands of times, every day. An improper function of those proteins (i.e., variation in expression, mutations onset, dysregulated channeling, differential protein-protein interactions) being part of this signaling network triggers a short circuit with severe acute and chronic pathological consequences reported as arrhythmias, cardiac remodeling, heart failure, reperfusion injury and cardiomyopathies. By acting with chemical, peptide-based and pharmacological modulators of these players, a correction of calcium homeostasis can be achieved accompanied by an amelioration of clinical symptoms. This review will focus on all those defects in calcium homeostasis which occur in the most common cardiac diseases, including myocardial infarction, arrhythmia, hypertrophy, heart failure and cardiomyopathies. This part will be introduced by the state of the art on the proteins involved in calcium homeostasis in cardiomyocytes and followed by the therapeutic treatments that to date, are able to target them and to revert the pathological phenotype.

Carfilzomib Treatment Causes Molecular and Functional Alterations of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Background Anticancer therapies have significantly improved patient outcomes; however, cardiac side effects from cancer therapies remain a significant challenge. Cardiotoxicity following treatment with proteasome inhibitors such as carfilzomib is known in clinical settings, but the underlying mechanisms have not been fully elucidated. Methods and Results Using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) as a cell model for drug-induced cytotoxicity in combination with traction force microscopy, functional assessments, high-throughput imaging, and comprehensive omic analyses, we examined the molecular mechanisms involved in structural and functional alterations induced by carfilzomib in hiPSC-CMs. Following the treatment of hiPSC-CMs with carfilzomib at 0.01 to 10 µmol/L, we observed a concentration-dependent increase in carfilzomib-induced toxicity and corresponding morphological, structural, and functional changes. Carfilzomib treatment reduced mitochondrial membrane potential, ATP production, and mitochondrial oxidative respiration and increased mitochondrial oxidative stress. In addition, carfilzomib treatment affected contractility of hiPSC-CMs in 3-dimensional microtissues. At a single cell level, carfilzomib treatment impaired Ca²⁺ transients and reduced integrin-mediated traction forces as detected by piconewton tension sensors. Transcriptomic and proteomic analyses revealed that carfilzomib treatment downregulated the expression of genes involved in extracellular matrices, integrin complex, and cardiac contraction, and upregulated stress responsive proteins including heat shock proteins. Conclusions Carfilzomib treatment causes deleterious changes in cellular and functional characteristics of hiPSC-CMs. Insights into these changes could be gained from the changes in the expression of genes and proteins identified from our omic analyses.

Cardioprotective effects of dantrolene in doxorubicin-induced cardiomyopathy in mice

BACKGROUND

Doxorubicin (Dox) is a potent chemotherapeutic agent, but its usage is limited by dose-dependent cardiotoxicity. Intracellular calcium dysregulation has been reported to be involved in doxorubicin-induced cardiomyopathy (DICM). The cardioprotective role of RyR stabilizer dantrolene (Dan) on the calcium dynamics of DICM has not yet been explored.

OBJECTIVE

To evaluate the effects of dantrolene on intracellular calcium dysregulation and cardiac contractile function in a DICM model.

METHODS

Adult male C57BL/6 mice were randomized into 4 groups: (1) Control, (2) Dox Only, (3) Dan Only, and (4) Dan + Dox. Fractional shortening (FS) and left ventricular ejection fraction (LVEF) were assessed by echocardiography. In addition, mice were sacrificed 2 weeks after doxorubicin injection for optical mapping of the heart in a Langendorff setup.

RESULTS

Treatment with Dox was associated with a reduction in both FS and LVEF at 2 weeks (P < .0001) and 4 weeks (P < .006). Dox treatment was also associated with prolongation of calcium transient durations CaTD50 (P = .0005) and CaTD80 (P < .0001) and reduction of calcium amplitude alternans ratio (P < .0001). Concomitant treatment with Dan prevented the Dox-induced decline in FS and LVEF (P < .002 at both 2 and 4 weeks). Dan also prevented Dox-induced prolongation of CaTD50 and CaTD80 and improved the CaT alternans ratio (P < .0001). Finally, calcium transient rise time was increased in the doxorubicin-treated group, indicating RyR2 dyssynchrony, and dantrolene prevented this prolongation (P = .02).

CONCLUSION

Dantrolene prevents cardiac contractile dysfunction following doxorubicin treatment by mitigating dysregulation of calcium dynamics.

One-dimensional scanning multiphoton imaging reveals prolonged calcium transient and sarcomere contraction in a zebrafish model of doxorubicin cardiotoxicity

Doxorubicin (DOX) is a potent chemotherapeutic agent known to induce cardiotoxicity. Here we applied one-dimensional scanning multiphoton imaging to investigate the derangement of cardiac dynamics induced by DOX on a zebrafish model. DOX changed the cell morphology and significantly prolonged calcium transient and sarcomere contraction, leading to an arrhythmia-like contractile disorder. The restoration phase of calcium transient dominated the overall prolongation, indicating that DOX perturbed primarily the protein functions responsible for recycling cytosolic calcium ions. This novel finding supplements the existing mechanism of DOX cardiotoxicity. We anticipate that this approach should help mechanistic studies of drug-induced cardiotoxicity or heart diseases.

Exercise, but Not Metformin Prevents Loss of Muscle Function Due to Doxorubicin in Mice Using an In Situ Method

Though effective in treating various types of cancer, the chemotherapeutic doxorubicin (DOX) is associated with skeletal muscle wasting and fatigue. The purpose of this study was to assess muscle function in situ following DOX administration in mice. Furthermore, pre-treatments with exercise (EX) or metformin (MET) were used in an attempt to preserve muscle function following DOX. Mice were assigned to the following groups: control, DOX, DOX + EX, or DOX + MET, and were given a single injection of DOX (15 mg/kg) or saline 3 days prior to sacrifice. Preceding the DOX injection, DOX + EX mice performed 60 min/day of running for 5 days, while DOX + MET mice received 5 daily oral doses of 500 mg/kg MET. Gastrocnemius–plantaris–soleus complex function was assessed in situ via direct stimulation of the sciatic nerve. DOX treatment increased time to half-relaxation following contractions, indicating impaired recovery (p < 0.05). Interestingly, EX prevented any increase in half-relaxation time, while MET did not. An impaired relaxation rate was associated with a reduction in SERCA1 protein content (p = 0.07) and AMPK phosphorylation (p < 0.05). There were no differences between groups in force production or mitochondrial respiration. These results suggest that EX, but not MET may be an effective strategy for the prevention of muscle fatigue following DOX administration in mice.

Sublethal doxorubicin promotes migration and invasion of breast cancer cells: role of Src Family non-receptor tyrosine kinases

BACKGROUND

Doxorubicin (Dox) is a widely used chemotherapy, but its effectiveness is limited by dose-dependent side effects. Although lower Dox doses reduce this risk, studies have reported higher recurrence of local disease with no improvement in survival rate in patients receiving low doses of Dox. To effectively mitigate this, a better understanding of the adverse effects of suboptimal Dox doses is needed.

METHODS

Effects of sublethal dose of Dox on phenotypic changes were assessed with light and confocal microscopy. Migratory and invasive behavior were assessed by wound healing and transwell migration assays. MTT and LDH release assays were used to analyze cell growth and cytotoxicity. Flow cytometry was employed to detect cell surface markers of cancer stem cell population. Expression and activity of matrix metalloproteinases were probed with qRT-PCR and zymogen assay. To identify pathways affected by sublethal dose of Dox, exploratory RNAseq was performed and results were verified by qRT-PCR in multiple cell lines (MCF7, ZR75-1 and U-2OS). Regulation of Src Family kinases (SFK) by key players in DNA damage response was assessed by siRNA knockdown along with western blot and qRT-PCR. Dasatinib and siRNA for Fyn and Yes was employed to inhibit SFKs and verify their role in increased migration and invasion in MCF7 cells treated with sublethal doses of Dox.

RESULTS

The results show that sublethal Dox treatment leads to increased migration and invasion in otherwise non-invasive MCF7 breast cancer cells. Mechanistically, these effects were independent of the epithelial mesenchymal transition, were not due to increased cancer stem cell population, and were not observed with other chemotherapies. Instead, sublethal Dox induces expression of multiple SFK-including Fyn, Yes, and Src-partly in a p53 and ATR-dependent manner. These effects were validated in multiple cell lines. Functionally, inhibiting SFKs with Dasatinib and specific downregulation of Fyn suppressed Dox-induced migration and invasion of MCF7 cells.

CONCLUSIONS

Overall, this study demonstrates that sublethal doses of Dox activate a pro-invasive, pro-migration program in cancer cells. Furthermore, by identifying SFKs as key mediators of these effects, our results define a potential therapeutic strategy to mitigate local invasion through co-treatment with Dasatinib.

Understanding doxorubicin associated calcium remodeling during triple-negative breast cancer treatment: an in silico study

Aim:

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer with high heterogeneity, rapid progression, and paucity of treatment options. The most effective chemotherapeutic drug used to treat TNBC is doxorubicin (Doxo) which is an anthracycline antibiotic. However, Doxo treatment alters cytosolic calcium dynamics leading to drug-resistance condition. The aim of this study is to capture the alterations in the activity of various calcium channels and pumps during Doxo treatment and their consequences on cytosolic calcium dynamics that ultimately result in drug resistance.

Methods:

In the present study, a mathematical model is proposed to capture the complex dynamical landscape of intracellular calcium during Doxo treatment. This study provides an insight into Doxo remodeling of calcium dynamics and associated drug-resistance effect. The model was first analyzed analytically and then explored through numerical simulation using techniques like global sensitivity analysis, parameter recalibration, etc.

Results:

The model is used to predict the potential combination therapy for Doxo that can overcome Doxo associated drug resistance. The results show targeting the dysregulated Ca²⁺ channels and pumps might provide efficient chemotherapy in TNBC. It was also observed that the indispensability of calcium influx rate is paramount in the Doxo drug resistance. Finally, three drugs were identified from existing literature that could be used as a combination therapy along with Doxo.

Conclusions:

The investigation highlights the importance of integrating the calcium signaling of various calcium regulating compounds for their effective anti-tumor effects deliverance along with chemotherapeutic agents. The results from this study might provide a new direction to the experimental biologists to explore different combination therapies with Doxo to enhance its anti-tumor effect.

Human Pluripotent Stem Cells for Modeling of Anticancer Therapy-Induced Cardiotoxicity and Cardioprotective Drug Discovery

Anticancer chemotherapies have been shown to produce severe side effects, with cardiotoxicity from anthracycline being the most notable. Identifying risk factors for anticancer therapy-induced cardiotoxicity in cancer patients as well as understanding its underlying mechanism is essential to improving clinical outcomes of chemotherapy treatment regimens. Moreover, cardioprotective agents against anticancer therapy-induced cardiotoxicity are scarce. Human induced pluripotent stem cell technology offers an attractive platform for validation of potential single nucleotide polymorphism with increased risk for cardiotoxicity. Successful validation of risk factors and mechanism of cardiotoxicity would aid the development of such platform for novel drug discovery and facilitate the practice of personalized medicine.

Protective effect of nanocurcumin against neurotoxicity induced by doxorubicin in rat's brain

Cognitive impairment is one of the serious side effects that cancer-treated patients suffer from after treatment by doxorubicin (DOX). Investigating the mechanisms underlying this impairment is crucial for its treatment or prevention. The current study investigates the cortical and hippocampal neurochemical changes induced by an acute dose of DOX (20 mg/kg, i.p.) and evaluates the neuroprotective effect of nanocurcumin (NC) (50 mg/kg, p.o.) against these changes. Animals were randomly divided into four groups, control, rats treated with either NC or DOX, and the fourth group treated with NC prior to DOX. Cortical dopamine level has significantly increased (71.88 %) after DOX injection. This was associated with a significant rise in the levels of lipid peroxidation (183.99 %, 201.4 %) and nitric oxide (36.54 %, 55 %) and a significant reduction in reduced glutathione (13 %, 21.44 %) in the cortex and hippocampus, respectively. In addition, DOX inhibited the cortical and hippocampal activities of acetylcholinesterase (94.82 %, 62.75 %) and monoamine oxidase (64.40 %, 68.84 %), respectively. Protection with NC mitigates the changes induced in the oxidative stress parameters by DOX. However, the effect on the activities of AchE and MAO was insignificant. This was reflected in the level of dopamine that showed non-significant changes in comparison to control and DOX-treated rats. The present findings indicate that oxidative stress, inhibition in AchE, MAO, and the subsequent elevation in dopamine could have a crucial role in mediating the chemo-brain adverse effects induced by DOX. In addition, protection with NC mitigated some of these adverse effects thus rendering DOX more tolerable.

Noncoding RNAs in doxorubicin-induced cardiotoxicity and their potential as biomarkers and therapeutic targets

Anthracyclines, such as doxorubicin (DOX), are well known for their high efficacy in treating multiple cancers, but their clinical usage is limited due to their potential to induce fatal cardiotoxicity. Such detrimental effects significantly impact the overall physical condition or even induce the morbidity and mortality of cancer survivors. Therefore, it is extremely important to understand the mechanisms of DOX-induced cardiotoxicity to develop methods for the early detection of cytotoxicity and therapeutic applications. Studies have shown that many molecular events are involved in DOX-induced cardiotoxicity. However, the precise mechanisms are still not completely understood. Recently, noncoding RNAs (ncRNAs) have been extensively studied in a diverse range of regulatory roles in cellular physiological and pathological processes. With respect to their roles in DOX-induced cardiotoxicity, microRNAs (miRNAs) are the most widely studied, and studies have focused on the regulatory roles of long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), which have been shown to have significant functions in the cardiovascular system. Recent discoveries on the roles of ncRNAs in DOX-induced cardiotoxicity have prompted extensive interest in exploring candidate ncRNAs for utilization as potential therapeutic targets and/or diagnostic biomarkers. This review presents the frontier studies on the roles of ncRNAs in DOX-induced cardiotoxicity, addresses the possibility and prospects of using ncRNAs as diagnostic biomarkers or therapeutic targets, and discusses the possible reasons for related discrepancies and limitations of their use.

Cardioprotective effect of Malva verticillata against doxorubicin -induced toxicity in rats

Background

M. verticillata (Malvaceae) is a medicinal plant used in the treatment of wounds, boils, and liver injuries. The plant leaf extracts possess anti-inflammatory and antioxidant activities. Doxorubicin (DOX) is a potent chemotherapeutic agent used in the treatment of various cancers, but its clinical use is limited by acute and chronic cardiotoxicity. This study aims to evaluate the possible cardioprotective role of Malva verticillata against doxorubicin-induced cardiotoxicity.

Method

Thirty-six male albino rats were divided into six groups, (n = 6): G1: normal control (was given 1 ml/kg of NaCl, 0.9%, twice a week IP), G2: cardiotoxic group (was given 1 mg/kg of DOX twice a week IP). G3 and G4 were given 250 mg/kg and 500 mg/kg of M. verticillata, respectively, while G5 and G6: were given 250, 500 mg/kg of M. verticillata PO and 1 mg/kg IP of DOX. for 6 weeks. Total body weight was taken weekly and Heart: body weight ratio was calculated. Blood samples were collected for determination of serum lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and Troponin, the hearts were removed and processed for histopathological examination.

Results

M. verticillata showed a significant dose-dependent reduction in the cardiac enzyme levels, LDH, CPK activities, and Troponin levels. The histopathological studies in rat hearts also supported those findings.

Conclusion

The present study suggests that M. verticillata may have a novel and worthwhile cardioprotective effect against DOX-induced cardiotoxicity.

Cardio-protective impact of gabapentin against doxorubicin-induced myocardial toxicity in rats; emphasis on modulation of inflammatory-apoptotic signaling

PURPOSE

Cardiotoxicity is one of the most commonly encountered adverse effects observed alongside the therapeutic use of doxorubicin (DOX), thus curbing its therapeutic utility.

METHODS

The current study was conducted to evaluate the cardioprotective effect of gabapentin (Gaba), a Ca + 2 channel blocker with emerging pharmacological merits, against DOX-induced cardiotoxicity. Gaba was orally administered at two dose levels (10 and 30 mg/kg) for 21 days parallel to DOX injection.

RESULTS

DOX induced significant functional, biochemical, and histopathological injury to the myocardium. Gaba treatment revealed a cardioprotective effect as manifested in the significant restoration of electrocardiogram parameters, including the heart rate, ST segment elevation, QRS and T wave amplitudes, and QT and PR intervals. The biomarkers of myocardial injury, namely serum creatine kinase, aspartate aminotransferase, and lactate dehydrogenase activities, significantly declined as well as the concomitant improvement of the myocardial oxidative status. Mechanistically, Gaba treatment significantly reduced the myocardial contents of c-Jun N-terminal kinase (JNK), the major modulator of inflammatory/apoptotic signaling. However, the myocardial contents of the apoptotic biomarkers caspase-8 and TRAIL also significantly declined. In isolated cardiomyocytes, Gaba treatment maintained the morphological characteristics of the cardiomyocytes and preserved their spontaneous beating characteristics. Nevertheless, the protein expression of caspase-8, JNK 1/2, and CD95L significantly declined with Gaba treatment.

CONCLUSION

Gaba confers cardioprotective effects against DOX-induced myocardial injury and cardiotoxicity by modulating the inflammatory/apoptotic signaling pathway.

Vitamin C: historical perspectives and heart failure

Vitamin C (Vit C) is an ideal antioxidant as it is easily available, water soluble, very potent, least toxic, regenerates other antioxidants particularly Vit E, and acts as a cofactor for different enzymes. It has received much attention due to its ability in limiting reactive oxygen species, oxidative stress, and nitrosative stress, as well as it helps to maintain some of the normal metabolic functions of the cell. However, over 140 clinical trials using Vit C in different pathological conditions such as myocardial infarction, gastritis, diabetes, hypertension, stroke, and cancer have yielded inconsistent results. Such a divergence calls for new strategies to establish practical significance of Vit C in heart failure or even in its prevention. For a better understanding of Vit C functioning, it is important to revisit its transport across the cell membrane and subcellular interactions. In this review, we have highlighted some historical details of Vit C and its transporters in the heart with a particular focus on heart failure in cancer chemotherapy.

A short review: Doxorubicin and its effect on cardiac proteins

Doxorubicin (DOX) is a boon for cancer-suffering patients. However, the undesirable effect on health on vital organs, especially the heart, is a limiting factor, resulting in an increased number of patients with cardiac dysfunction. The present review focuses on the contractile machinery and associated factors, which get affected due to DOX toxicity in chemo-patients for which they are kept under life-long investigation for cardiac function. DOX-induced oxidative stress disrupts the integrity of cardiac contractile muscle proteins that alter the rhythmic mechanism and oxygen consumption rate of the heart. DOX is an oxidant and it is further discussed that oxidative stress prompts the damage of contractile components and associated factors, which include Ca²⁺ load through Ca²⁺ ATPase, SERCA, ryanodine receptor-2, phospholamban, and calsequestrin, which ultimately results in left ventricular ejection and dilation. Based on data and evidence, the associated proteins can be considered as clinical markers to develop medications for patients. Even with the advancement of various diagnosing tools and modified drugs to mitigate DOX-induced cardiotoxicity, the risk could not be surmounted with survivors of cancer.

Signaling Pathways Underlying Anthracycline Cardiotoxicity

Significance: The cardiac side effects of hematological treatments are a major issue of the growing population of cancer survivors, often affecting patient survival even more than the tumor for which the treatment was initially prescribed. Among the most cardiotoxic drugs are anthracyclines (ANTs), highly potent antitumor agents, which still represent a mainstay in the treatment of hematological and solid tumors. Unfortunately, diagnosis, prevention, and treatment of cardiotoxicity are still unmet clinical needs, which call for a better understanding of the molecular mechanism behind the pathology. Recent Advances: This review article will discuss recent findings on the pathomechanisms underlying the cardiotoxicity of ANTs, spanning from DNA and mitochondrial damage to calcium homeostasis, autophagy, and apoptosis. Special emphasis will be given to the role of reactive oxygen species and their interplay with major signaling pathways. Critical Issues: Although new promising therapeutic targets and new drugs have started to be identified, their efficacy has been mainly proven in preclinical studies and requires clinical validation. Future Directions: Future studies are awaited to confirm the relevance of recently uncovered targets, as well as to identify new druggable pathways, in more clinically relevant models, including, for example, human induced pluripotent stem cell-derived cardiomyocytes.

Acylated Ghrelin Protects the Hearts of Rats from Doxorubicin-Induced Fas/FasL Apoptosis by Stimulating SERCA2a Mediated by Activation of PKA and Akt

This study investigated if the cardioprotective effect of acylated ghrelin (AG) against doxorubicin (DOX)-induced cardiac toxicity in rats involves inhibition of Fas/FasL-mediated cell death. It also investigated if such an effect is mediated by restoring Ca⁺² homeostasis from the aspect of stimulation of SERCA2a receptors. Adult male Wistar rats were divided into 4 groups (20 rats/each) as control, control + AG, DOX, and DOX + AG. AG was co-administered to all rats consecutively for 35 days. In addition, isolated cardiomyocytes were cultured and treated with AG in the presence or absence of DOX with or without pre-incubation with [D-Lys3]-GHRP-6 (a AG receptor antagonist), VIII (]an Akt inhibitor), or KT-5720 (a PKA inhibitor). AG increased LVSP, dp/dt_max, and dp/dt_min in both control and DOX-treated animals and improved cardiac ultrastructural changes in DOX-treated rats. It also inhibited ROS in control rats and lowered LVEDP, intracellular levels of ROS and Ca²⁺, and activity of calcineurin in LVs of DOX-treated rats. Concomitantly, it inhibited LV NFAT-4 nuclear translocation and downregulated their protein levels of Fas and FasL. Mechanistically, in control or DOX-treated hearts or cells, AG upregulated the levels of SERCA2a and increased the activities of PKA and Akt, leading to increase phosphorylation of phospholamban at Ser¹⁶ and Thr¹⁷. All these effects were abolished by D-Lys3-GHRP-6, VIII, or KT-5720 and were independent of food intake or GH/IGF-1. In conclusion, AG cardioprotection against DOX involves inhibition of extrinsic cell death and restoring normal Ca⁺² homeostasis.

The Role of Oxidative Stress in Cardiac Disease: From Physiological Response to Injury Factor

Reactive oxygen species (ROS) are highly reactive chemical species containing oxygen, controlled by both enzymatic and nonenzymatic antioxidant defense systems. In the heart, ROS play an important role in cell homeostasis, by modulating cell proliferation, differentiation, and excitation-contraction coupling. Oxidative stress occurs when ROS production exceeds the buffering capacity of the antioxidant defense systems, leading to cellular and molecular abnormalities, ultimately resulting in cardiac dysfunction. In this review, we will discuss the physiological sources of ROS in the heart, the mechanisms of oxidative stress-related myocardial injury, and the implications of experimental studies and clinical trials with antioxidant therapies in cardiovascular diseases.

Suppression of Ca2+ signals by EGR4 controls Th1 differentiation and anti-cancer immunity in vivo

While the zinc finger transcription factors EGR1, EGR2, and EGR3 are recognized as critical for T-cell function, the role of EGR4 remains unstudied. Here, we show that EGR4 is rapidly upregulated upon TCR engagement, serving as a critical "brake" on T-cell activation. Hence, TCR engagement of EGR4^-/- T cells leads to enhanced Ca²⁺ responses, driving sustained NFAT activation and hyperproliferation. This causes profound increases in IFNγ production under resting and diverse polarizing conditions that could be reversed by pharmacological attenuation of Ca²⁺ entry. Finally, an in vivo melanoma lung colonization assay reveals enhanced anti-tumor immunity in EGR4^-/- mice, attributable to Th1 bias, Treg loss, and increased CTL generation in the tumor microenvironment. Overall, these observations reveal for the first time that EGR4 is a key regulator of T-cell differentiation and function.

Mitochondrial Determinants of Doxorubicin-Induced Cardiomyopathy

Anthracycline-based chemotherapy can result in the development of a cumulative and progressively developing cardiomyopathy. Doxorubicin is one of the most highly prescribed anthracyclines in the United States due to its broad spectrum of therapeutic efficacy. Interference with different mitochondrial processes is chief among the molecular and cellular determinants of doxorubicin cardiotoxicity, contributing to the development of cardiomyopathy. The present review provides the basis for the involvement of mitochondrial toxicity in the different functional hallmarks of anthracycline toxicity. Our objective is to understand the molecular determinants of a progressive deterioration of functional integrity of mitochondria that establishes a historic record of past drug treatments (mitochondrial memory) and renders the cancer patient susceptible to subsequent regimens of drug therapy. We focus on the involvement of doxorubicin-induced mitochondrial oxidative stress, disruption of mitochondrial oxidative phosphorylation, and permeability transition, contributing to altered metabolic and redox circuits in cardiac cells, ultimately culminating in disturbances of autophagy/mitophagy fluxes and increased apoptosis. We also suggest some possible pharmacological and nonpharmacological interventions that can reduce mitochondrial damage. Understanding the key role of mitochondria in doxorubicin-induced cardiomyopathy is essential to reduce the barriers that so dramatically limit the clinical success of this essential anticancer chemotherapy.

Single-nucleotide polymorphisms in a short basic motif in the ABC transporter ABCG2 disable its trafficking out of endoplasmic reticulum and reduce cell resistance to anticancer drugs

ATP-binding cassette (ABC) subfamily G member 2 (ABCG2) belongs to the ABC transporter superfamily and has been implicated in multidrug resistance of cancers. Although the structure and function of ABCG2 have been extensively studied, little is known about its biogenesis and the regulation thereof. In this study, using mutagenesis and several biochemical analyses, we show that the positive charges in the vicinity of the RKR motif downstream of the ABC signature drive trafficking of nascent ABCG2 out of the endoplasmic reticulum (ER) onto plasma membranes. Substitutions of and naturally occurring single-nucleotide polymorphisms within these positively charged residues disabled the trafficking of ABCG2 out of the ER. A representative ABCG2 variant in which the RKR motif had been altered underwent increased ER stress-associated degradation. We also found that unlike WT ABCG2, genetic ABCG2 RKR variants have disrupted normal maturation and do not reduce accumulation of the anticancer drug mitoxantrone and no longer confer resistance to the drug. We conclude that the positive charges downstream of the ABC signature motif critically regulate ABCG2 trafficking and maturation. We propose that single-nucleotide polymorphisms of these residues reduce ABCG2 expression via ER stress-associated degradation pathway and may contribute to reduced cancer drug resistance, improving the success of cancer chemotherapy.

Major obstacles to doxorubicin therapy: Cardiotoxicity and drug resistance

Background

Doxorubicin is one of the most commonly prescribed and time-tested anticancer drugs. Although being considered as a first line drug in different types of cancers, the two main obstacles to doxorubicin therapy are drug-induced cardiotoxicity and drug resistance.

Method

The study utilizes systemic reviews on publications of previous studies obtained from scholarly journal databases including PubMed, Medline, Ebsco Host, Google Scholar, and Cochrane. The study utilizes secondary information obtained from health organizations using filters and keywords to sustain information relevancy. The study utilizes information retrieved from studies captured in the peer-reviewed journals on “doxorubicin-induced cardiotoxicity” and “doxorubicin resistance.”

Discussion and results

The exact mechanisms of cardiotoxicity are not known; various hypotheses are studied. Doxorubicin can lead to free radical generation in various ways. The commonly proposed underlying mechanisms promoting doxorubicin resistance are the expression of multidrug resistance proteins as well as other causes.

Conclusion

In this review, we have described the major obstacles to doxorubicin therapy, doxorubicin-induced cardiotoxicity as well as the mechanisms of cancer drug resistance and in following the treatment failures.

Effects of Resistance Exercise Training on Doxorubicin-Induced Cardiotoxicity

Although highly effective, doxorubicin (DOX) use is limited by a dose-dependent cardiotoxicity. The purpose of this study was to determine whether resistance training (RT) would protect against DOX-induced cardiac dysfunction and determine whether any observed functional preservation is a result of reduced lipid peroxidation or a preservation of the cardiac myosin heavy chain (MHC) isoform distribution. Rats were resistance-trained or remained sedentary for 12 weeks, then treated with 12.5 mg/kg DOX or 0.9% saline. Five days after DOX exposure, cardiac function, lipid peroxidation, and MHC isoform expression were quantified. RT preserved cardiac function and attenuated the α-to β-MHC shift that occurs with DOX treatment. No significant differences in lipid peroxidation were observed between sedentary and RT animals treated with DOX. These data suggest that resistance-type exercise can provide protection against DOX-induced cardiac dysfunction, which may be a result of a preservation of the cardiac MHC isoform distribution.

Muscle contractility dysfunction precedes loss of motor unit connectivity in SOD1(G93A) mice

INTRODUCTION

Electrophysiological measurements are used in longitudinal clinical studies to provide insight into the progression of amyotrophic lateral sclerosis (ALS) and the relationship between muscle weakness and motor unit (MU) degeneration. Here, we used a similar longitudinal approach in the Cu/Zn superoxide dismutase (SOD1[G93A]) mouse model of ALS.

METHODS

In vivo muscle contractility and MU connectivity assays were assessed longitudinally in SOD1(G93A) and wild type mice from postnatal days 35 to 119.

RESULTS

In SOD1(G93A) males, muscle contractility was reduced by day 35 and preceded MU loss. Muscle contractility and motor unit reduction were delayed in SOD1(G93A) females compared with males, but, just as with males, muscle contractility reduction preceded MU loss.

DISCUSSION

The longitudinal contractility and connectivity paradigm employed here provides additional insight into the SOD1(G93A) mouse model and suggests that loss of muscle contractility is an early finding that may precede loss of MUs and motor neuron death. Muscle Nerve 59:254-262, 2019.

EGR-mediated control of STIM expression and function

Ca²⁺ is a ubiquitous, dynamic and pluripotent second messenger with highly context-dependent roles in complex cellular processes such as differentiation, proliferation, and cell death. These Ca²⁺ signals are generated by Ca²⁺-permeable channels located on the plasma membrane (PM) and endoplasmic reticulum (ER) and shaped by PM- and ER-localized pumps and transporters. Differences in the expression of these Ca²⁺ homeostasis proteins contribute to cell and context-dependent differences in the spatiotemporal organization of Ca²⁺ signals and, ultimately, cell fate. This review focuses on the Early Growth Response (EGR) family of zinc finger transcription factors and their role in the transcriptional regulation of Stromal Interaction Molecule (STIM1), a critical regulator of Ca²⁺ entry in both excitable and non-excitable cells.

Untying the knot: protein quality control in inherited cardiomyopathies

Mutations in genes encoding sarcomeric proteins are the most important causes of inherited cardiomyopathies, which are a major cause of mortality and morbidity worldwide. Although genetic screening procedures for early disease detection have been improved significantly, treatment to prevent or delay mutation-induced cardiac disease onset is lacking. Recent findings indicate that loss of protein quality control (PQC) is a central factor in the disease pathology leading to derailment of cellular protein homeostasis. Loss of PQC includes impairment of heat shock proteins, the ubiquitin-proteasome system, and autophagy. This may result in accumulation of misfolded and aggregation-prone mutant proteins, loss of sarcomeric and cytoskeletal proteins, and, ultimately, loss of cardiac function. PQC derailment can be a direct effect of the mutation-induced activation, a compensatory mechanism due to mutation-induced cellular dysfunction or a consequence of the simultaneous occurrence of the mutation and a secondary hit. In this review, we discuss recent mechanistic findings on the role of proteostasis derailment in inherited cardiomyopathies, with special focus on sarcomeric gene mutations and possible therapeutic applications.

Anticancer drug-induced cardiac rhythm disorders: Current knowledge and basic underlying mechanisms

Significant advances in cancer treatment have resulted in decreased cancer related mortality for many malignancies with some cancer types now considered chronic diseases. Despite these improvements, there is increasing recognition that many cancer patients or cancer survivors can develop cardiovascular diseases, either due to the cancer itself or as a result of anticancer therapy. Much attention has focused on heart failure; however, other cardiotoxicities, notably cardiac rhythm disorders, can occur without underlying cardiomyopathy. Supraventricular tachycardias occur in cancer patients treated with cytotoxic chemotherapy (anthracyclines, gemcitabine, cisplatin and alkylating-agents) or kinase-inhibitors (KIs) such as ibrutinib. Ventricular arrhythmias, with a subset of them being torsades-de-pointes (TdP) favored by QTc prolongation have been reported: this may be the result of direct hERG-channel inhibition or a more recently-described mechanism of phosphoinositide-3-kinase inhibition. The major anticancer drugs responsible for QTc prolongation in this context are KIs, arsenic trioxide, anthracyclines, histone deacetylase inhibitors, and selective estrogen receptor modulators. Anticancer drug-induced cardiac rhythm disorders remain an underappreciated complication even by experienced clinicians. Moreover, the causal relationship of a particular anticancer drug with cardiac arrhythmia occurrence remains challenging due in part to patient comorbidities and complex treatment regimens. For example, any cancer patient may also be diagnosed with common diseases such as hypertension, diabetes or heart failure which increase an individual's arrhythmia susceptibility. Further, anticancer drugs are generally usually used in combination, increasing the challenge around establishing causation. Thus, arrhythmias appear to be an underappreciated adverse effect of anticancer agents and the incidence, significance and underlying mechanisms are now being investigated.

Recent progress in doxorubicin-induced cardiotoxicity and protective potential of natural products

BACKGROUND

As an anthracycline antibiotic, doxorubicin (DOX) is one of the most potent and widely used chemotherapeutic agents for various types of solid tumors. Unfortunately, clinical application of this drug results in severe side effects of cardiotoxicity.

PURPOSE

We aim to review the research focused on elimination or reduction of DOX cardiotoxicity without affecting its anticancer efficacy by natural products.

METHODS

This study is based on pertinent papers that were retrieved by a selective search using relevant keywords in PubMed and ScienceDirect. The literature mainly focusing on natural products and herb extracts with therapeutic efficacies against experimental models both in vitro and in vivo was identified.

RESULTS

Current evidence revealed that multiple molecules and signaling pathways, such as oxidative stress, iron metabolism, and inflammation, are associated with DOX-induced cardiotoxicity. Based on these knowledge, various strategies were proposed, and thousands of compounds were screened. A number of natural products and herb extracts demonstrated potency in limiting DOX cardiotoxicity toward cultured cells and experimental animal models.

CONCLUSIONS

Though a panel of natural products and herb extracts demonstrate protective effects on DOX-induced cardiotoxicity in cells and animal models, their therapeutic potentials for clinical needs further investigation.

Cardioprotective action of the aqueous extract of Terminalia arjuna bark against toxicity induced by doxorubicin

BACKGROUND

The aqueous extract of Terminalia arjuna (TA) bark (TA_AqE) has been shown to have a direct inotropic effect on ventricular myocytes. Active constituents of TA_AqE contain various flavonoids and proanthocyanidins, some of which are known to have antioxidant activities. Whether TA_AqE affords a cardioprotective action against oxidative stress (OS) remains unclear.

PURPOSE

Increased OS is one of the major mechanisms underlying cardiotoxicity induced by doxorubicin (DOX), a commonly-used anticancer agent. The aim of the present study was to investigate potential cardioprotective effect of TA_AqE against DOX-induced OS and cardiac dysfunction.

METHODS

OS and cytotoxicity were induced by 1 µM DOX for 24 h in H9c2 cells, a cardiac tissue-derived cell line, and left ventricular (LV) dysfunction was induced by intrapleural injection of DOX (accumulative 20 mg/kg body weight) to mice. Cellular oxidative levels and morphology were assessed using microscopy and oxidative-sensitive fluorescent dyes with and without co-treatment with TA_AqE. LV function was monitored weekly with echocardiography.

RESULTS

TA_AqE reduced OS and preserved mitochondria and cell growth of H9c2 cells against DOX treatment. TA_AqE (in drinking water) attenuated the decreased LV function and altered myocardial structure caused by DOX treatment.

CONCLUSION

TA_AqE exerts a protective action against cardiotoxicity caused by DOX in part via suppression of OS. Thus, TA_AqE is a promising cardiotonic in adjuvant cancer chemotherapy.

The Formin, DIAPH1, is a Key Modulator of Myocardial Ischemia/Reperfusion Injury

The biochemical, ionic, and signaling changes that occur within cardiomyocytes subjected to ischemia are exacerbated by reperfusion; however, the precise mechanisms mediating myocardial ischemia/reperfusion (I/R) injury have not been fully elucidated. The receptor for advanced glycation end-products (RAGE) regulates the cellular response to cardiac tissue damage in I/R, an effect potentially mediated by the binding of the RAGE cytoplasmic domain to the diaphanous-related formin, DIAPH1. The aim of this study was to investigate the role of DIAPH1 in the physiological response to experimental myocardial I/R in mice. After subjecting wild-type mice to experimental I/R, myocardial DIAPH1 expression was increased, an effect that was echoed following hypoxia/reoxygenation (H/R) in H9C2 and AC16 cells. Further, compared to wild-type mice, genetic deletion of Diaph1 reduced infarct size and improved contractile function after I/R. Silencing Diaph1 in H9C2 cells subjected to H/R downregulated actin polymerization and serum response factor-regulated gene expression. Importantly, these changes led to increased expression of sarcoplasmic reticulum Ca2+ ATPase and reduced expression of the sodium calcium exchanger. This work demonstrates that DIAPH1 is required for the myocardial response to I/R, and that targeting DIAPH1 may represent an adjunctive approach for myocardial salvage after acute infarction.

Thrombopoietin protects H9C2 cells from excessive autophagy and apoptosis in doxorubicin-induced cardiotoxicity

Cardiac toxicity has been the major concern when using doxorubicin (DOX) in cancer therapy. Thrombopoietin (TPO) protects cardiac cells from DOX-induced cell damage; however, its molecular mechanism remains exclusive. The anti-autophagic and anti-apoptotic effects of TPO upon DOX treatment were studied in the cardiac H9C2 cell line, with bafilomycin A1 treatment as a positive control for autophagy inhibition. Cell viability was measured by Cell Counting Kit-8 assay in different treatment groups. The mRNA and/or protein levels of apoptotic markers and autophagy-associated factors were detected. The mean number of microtubule-associated protein 1A/1B-light chain 3 (LC3) puncta per cell was quantified to indicate autophagosomes and autolysosomes, of which the ones co-stained with lysosomal-associated membrane protein 1 were considered as autolysosomes. DOX treatment (5 µg/ml, 24 h) significantly impaired H9C2 cell viability compared with the control, while TPO pretreatment (10 ng/ml, 36 h) improved cell viability upon DOX treatment. DOX exposure markedly increased LC3 puncta in H9C2 cells, and TPO pretreatment reduced the number of autophagosomes, but showed no significant inhibitory effect on autolysosome formation. The autophagy inhibition by TPO upon DOX treatment was confirmed according to protein quantification of LC3-II and nucleoporin 62. TPO also suppressed autophagy-promoting protein Beclin-1, and elevated the anti-autophagic factors GATA-binding protein-4 and B cell lymphoma-2. Furthermore, TPO reduced DOX-induced apoptosis in H9C2 cells, as reflected by the amount changes of caspase-3. Taken together, these results revealed that TPO has a protective role in H9C2 cells from DOX-induced autophagy as well as apoptosis, and indicated that TPO may act as a cardioprotective drug in DOX-treated patients.

Effects of ranolazine in a model of doxorubicin-induced left ventricle diastolic dysfunction

BACKGROUND AND PURPOSE

Doxorubicin is a highly effective anticancer drug, but its clinical application is hampered by cardiotoxicity. Asymptomatic diastolic dysfunction can be the earliest manifestation of doxorubicin cardiotoxicity. Therefore, a search for therapeutic intervention that can interfere with early manifestations and possibly prevent later development of cardiotoxicity is warranted. Increased doxorubicin-dependent ROS may explain, in part, Ca²⁺ and Na⁺ overload that contributes to diastolic dysfunction and development of heart failure. Therefore, we tested whether the administration of ranolazine, a selective blocker of late Na⁺ current, immediately after completing doxorubicin therapy, could affect diastolic dysfunction and interfere with the progression of functional decline.

EXPERIMENTAL APPROACH

Fischer 344 rats received a cumulative dose of doxorubicin of 15 mg·kg^-1 over a period of 2 weeks. After the assessment of diastolic dysfunction, the animals were treated with ranolazine (80 mg·kg^-1 , daily) for the following 4 weeks.

KEY RESULTS

While diastolic and systolic function progressively deteriorated in doxorubicin-treated animals, treatment with ranolazine relieved diastolic dysfunction and prevented worsening of systolic function, decreasing mortality. Ranolazine lowered myocardial NADPH oxidase 2 expression and oxidative/nitrative stress. Expression of the Na⁺ /Ca²⁺ exchanger 1 and Na_v 1.5 channels was reduced and of the sarcoplasmic/endoplasmic reticulum Ca²⁺ -ATPase 2 protein was increased. In addition, ranolazine lowered doxorubicin-induced hyper-phosphorylation and oxidation of Ca²⁺ /calmodulin-dependent protein kinase II, and decreased myocardial fibrosis.

CONCLUSIONS AND IMPLICATIONS

Ranolazine, by the increased Na⁺ influx, induced by doxorubicin, altered cardiac Ca²⁺ and Na⁺ handling and attenuated diastolic dysfunction induced by doxorubicin, thus preventing the progression of cardiomyopathy.

LINKED ARTICLES

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

Protein Quality Control Dysfunction in Cardiovascular Complications Induced by Anti-Cancer Drugs

Cardiovascular complications, including heart failure, hypertension, ischemic syndromes and venous thromboembolism, have been identified in patients treated with anti-cancer drugs. Oxidative stress, mitochondrial dysfunction and DNA synthesis inhibition are considered to be responsible for the cardiotoxicity induced by these agents. Protein quality control (PQC) has 3 major components, including the endoplasmic reticulum (ER), the ubiquitin-proteasome system (UPS) and the autophagy-lysosome system, and participates in protein folding and degradation to maintain protein homeostasis. We have demonstrated that PQC dysfunction is a new causal mechanism for the development of cardiac hypertrophy and failure. Increasing evidence shows that anti-cancer drugs, such as tyrosine kinase inhibitors, proteasome inhibitors, anthracyclines and autophagy inhibitors, cause PQC dysfunction. Here, we provide an overview of the potential role of PQC dysfunction in the development of cardiovascular complications induced by anti-cancer drugs.

Mechanisms of transcription factor acetylation and consequences in hearts

Acetylation of proteins as a post-translational modification is gaining rapid acceptance as a cellular control mechanism on par with other protein modification mechanisms such as phosphorylation and ubiquitination. Through genetic manipulations and evolving proteomic technologies, identification and consequences of transcription factor acetylation is beginning to emerge. In this review, we summarize the field and discuss newly unfolding mechanisms and consequences of transcription factor acetylation in normal and stressed hearts. This article is part of a Special Issue entitled: The role of post-translational protein modifications on heart and vascular metabolism edited by Jason R.B. Dyck & Jan F.C. Glatz.

Pentoxifylline abrogates cardiotoxicity induced by the administration of a single high dose or multiple low doses of doxorubicin in rats

Doxorubicin (DOX) possesses a broad-spectrum antineoplastic activity; however, its clinical application is impeded by cardiotoxicity. This study aimed to investigate the protective effect of pentoxifylline (PXF), which possesses antioxidant and anti-inflammatory properties against cardiotoxicity induced by a single high dose (15 mg/kg, i.p.) or multiple low doses (2.5 mg/kg, i.p., three times per week for 2 weeks) of DOX. At the end of the experimental period, the serum creatine kinase (CK)-MB and lactate dehydrogenase (LDH) activities were measured. The hearts were then removed for evaluating TNF-α, NO, malondialdehyde (MDA), and reduced glutathione (GSH) levels, superoxide dismutase (SOD) and catalase (CAT) activities, and the expression of iNOS, NF-κB, Fas ligand (FasL), and caspase-3. The administration of DOX in both dose regimens caused increases in serum CK-MB and LDH activities, in cardiac TNF-α, NO and MDA levels, as well as in the cardiac expression of iNOS, NF-κB, FasL and caspase-3, whereas it significantly reduced the cardiac GSH level, as well as SOD and CAT activities (P < 0.05). Prophylactic treatment of rats with PXF diminished DOX-induced alterations in theses parameters. Our results warrant the clinical use of PXF as an adjuvant therapy to abrogate cardiotoxicity of DOX and extend its clinical applications.