Doxorubicin-induced Cardiac Dysfunction Research Articles

The protective role of Baz2b ablation in aging-related heart failure

Abstract Background The elderly population is increasing year by year. Aging has become an important risk factor for cardiac dysfunction and heart failure. Previous studies have found that bromodomain adjacent to zinc finger 2B (Baz2b) is closely associated with neurodegeneration, but its role in aging-related heart failure remains unclear. Purpose We aim to explore the mechanism of Baz2b in aging-induced heart failure and doxorubicin-induced heart failure. We also investigate whether Baz2b and its downstream mechanism can serve as targets for clinical intervention. Methods We injected doxorubicin intraperitoneally in Baz2b knockout and cardiac-specific Baz2b knockdown mice to produce in vivo models. The effects of Baz2b and its downstream regulators were further explored via RNA-sequence, chromatin immunoprecipitation-sequence (ChIP-seq) and assay for transposase-accessible chromatin-sequence (ATAC-seq). Besides, we elucidated the function of Baz2b in alpha-myosin heavy chain-induced myocarditis. Results we found that Baz2b expression was upregulated in both aged and doxorubicin-induced mice heart. Baz2b knockout resulted in cardiac function recovery accompanied by a decline in apoptosis in aged mice and doxorubicin-induced mice. In contrast to control mice, cardiac-specific Baz2b knockdown alleviated doxorubicin-induced cardiac dysfunction and apoptosis. Mechanistically, Baz2b was closely associated with inflammatory responses in heart. It regulates Stat1, an important inflammatory downstream regulator via H3k4me3. Furthermore, the overexpression of Stat1 was able to abolish the protective role of Baz2b in doxorubicin-induced cardiotoxicity. Besides, cardiac-specific Baz2b knockdown could alleviated myocarditis, in line with the fact that Baz2b was linked to inflammation. Conclusion Taken together, this study provides new insights that Baz2b plays an important role in aging-related heart dysfunction. Since epigenetic readers were previously unrecognized, these findings may shed on novel clinical therapeutic choice for patients with chemotherapy-induced cardiotoxicity.The schematic diagram of Baz2b in heart

Small-molecule mediated MuRF1 inhibition protects from doxorubicin-induced cardiac atrophy and contractile dysfunction

Cancer chemotherapy induces cell stress in rapidly dividing cancer cells to trigger their growth arrest and apoptosis. However, adverse effects related to cardiotoxicity underpinned by a limited regenerative potential of the heart limits clinical application: In particular, chemotherapy with doxorubicin (DOXO) causes acute heart injury that can transition to persisting cardiomyopathy (DOXO-CM). Here, we tested if MuRF1 inhibition (“MuRFi”) was able to attenuate DOXO-CM. To mimic DOXO chemotherapy, we treated mice over four weeks with five DOXO injections, resulting in a cumulative dosage of 25 mg/kg. At day 28, mice had lower body and heart weights, reduced cardiac cross-sectional myofibrillar areas (CSAs), and disturbed functional ejection fractions (EFs) and fractional shortenings (FS) as indicated by echocardiography (ECHO). In contrast, mice with a 1 g/kg Myomed#205 spiked diet, a previously described experimental MuRFi therapy, showed lower DOXO-CM at day 28, and also reduced acute DOXO cardiac injury at day 7 (single DOXO dose; 15 mg/kg). Underlying molecular signatures using Western blot (WB) assays showed at day 28 reduced phospho-AKT (AKTp) and phospo-4EBP1 (4 EBP1p) levels following DOXO that were normalized following MuRFi treatment. Taken together, our data suggest that MuRFi treatment is suitable to attenuate DOXO-CM by preserving AKTp and 4 EBP1p levels in DOXO stressed cardiomyocytes, thereby supporting de novo protein translation and cardiomyocyte survival under translational arrest stress.

Cytotoxic T cells drive doxorubicin-induced cardiac fibrosis and systolic dysfunction.

Doxorubicin, the most prescribed chemotherapeutic drug, causes dose-dependent cardiotoxicity and heart failure. However, our understanding of the immune response elicited by doxorubicin is limited. Here we show that an aberrant CD8+ T cell immune response following doxorubicin-induced cardiac injury drives adverse remodeling and cardiomyopathy. Doxorubicin treatment in non-tumor-bearing mice increased circulating and cardiac IFNγ+CD8+ T cells and activated effector CD8+ T cells in lymphoid tissues. Moreover, doxorubicin promoted cardiac CD8+ T cell infiltration and depletion of CD8+ T cells in doxorubicin-treated mice decreased cardiac fibrosis and improved systolic function. Doxorubicin treatment induced ICAM-1 expression by cardiac fibroblasts resulting in enhanced CD8+ T cell adhesion and transformation, contact-dependent CD8+ degranulation and release of granzyme B. Canine lymphoma patients and human patients with hematopoietic malignancies showed increased circulating CD8+ T cells after doxorubicin treatment. In human cancer patients, T cells expressed IFNγ and CXCR3, and plasma levels of the CXCR3 ligands CXCL9 and CXCL10 correlated with decreased systolic function.

IF1 Knockout Protects Against Doxorubicin-Induced Cardiac Dysfunction by Improving Cardiomyocyte Energetics

Doxorubicin (DOX), a member of the Anthracycline antibiotics class, has been used as a potent chemotherapy agent against solid tumors. However, its use is limited by its cardiotoxicity. It is well-documented that mitochondrial dysfunction is one of the main mechanisms of DOX-induced cardiotoxicity. ATP synthase inhibitory subunit 1 (ATPIF1, or IF1) is an endogenous inhibitor of mitochondrial ATP synthase. Recent studies indicate that IF1 may suppress mitochondrial respiration via inhibiting ATP synthase. Others and our previous studies demonstrated that IF1 inactivation exerts hepatic and cardiac protective effects. We hypothesize that the absence of IF1 protects the heart from DOX-induced cardiotoxicity by improving mitochondrial energy metabolism. We first investigate the impact of IF1 KO on mitochondrial respiration using the high-resolution respirometer (OROBOROS) on freshly isolated cardiac mitochondria from IF1 KO and WT mice. IF1 KO mitochondria did show substantially increased state 2, state 3, and state 4 respiration rates compared with those of WT. We then investigated if WT and IF1 KO mice respond differently to DOX treatment. WT and IF1 KO mice at the ages of 12-16 weeks either received DOX 3mg/kg/every other day or vehicle intraperitoneally for two weeks. In vivo, cardiac function was evaluated using the VEVO F2 Echocardiographic system (Visual Sonic) 4 and 6 weeks after initiation of DOX and vehicle administration. Compared with the vehicle-treated WT mice, left ventricular ejection fraction (LVEF) was substantially decreased in DOX-treated WT mice compared with vehicle-treated WT mice. In contrast, LVEF in DOX-IF1 KO mice was substantially less reduced compared with vehicle-treated IF1 KO mice. We next investigated if improving cellular energetics is the critical mechanism underlying the protective effects of IF1 KO. Mouse neonatal cardiomyocyte (NMCM) isolated from WT and IF1 KO mice were cultured and treated with 0.5 and 1mM Dox for 24 hours. Cellular energetics were measured with the Mito stress assay using the Seahorse Bioanalyzer (96Xpro, Agilent). Basal, maximal, and ATP production-linked oxygen consumption rates were markedly decreased in DOX-treated-NMCM but not in DOX-treated IF1 KO NMCM compared with Vehicle-treated NMCM. In summary, the above in vivo and in vitro investigations support that IF1 inactivation is protective against DOX cardiac toxicity, at least partly, via improving cellular energetics; therefore, inactivating IF1 may be a potential therapeutic target to prevent and mitigate DOX-induced cardiomyopathy in patients. This research was supported by project number 5R01HL160969 from the National Heart Lung and Blood Institute at the NIH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Semaglutide attenuates doxorubicin-induced cardiotoxicity by ameliorating BNIP3-Mediated mitochondrial dysfunction

AimsDoxorubicin is a powerful chemotherapeutic agent for cancer, whose use is limited due to its potential cardiotoxicity. Semaglutide (SEMA), a novel analog of glucagon-like peptide-1 (GLP-1), has received widespread attention for the treatment of diabetes. However, increasing evidence has highlighted its potential therapeutic benefits on cardiac function. Therefore, the objective of this study was to examine the efficacy of semaglutide in ameliorating doxorubicin-induced cardiotoxicity. Methods and resultsDoxorubicin-induced cardiotoxicity is an established model to study cardiac function. Cardiac function was studied by transthoracic echocardiography and invasive hemodynamic monitoring. The results showed that semaglutide significantly ameliorated doxorubicin-induced cardiac dysfunction. RNA sequencing suggested that Bnip3 is the candidate gene that impaired the protective effect of semaglutide in doxorubicin-induced cardiotoxicity. To determine the role of BNIP3 on the effect of semaglutide in doxorubicin-induced cardiotoxicity, BNIP3 with adeno-associated virus serotype 9 (AAV9) expressing cardiac troponin T (cTnT) promoter was injected into tail vein of C57/BL6J mice to overexpress BNIP3, specifically in the heart. Overexpression of BNIP3 prevented the improvement in cardiac function caused by semaglutide. In vitro experiments showed that semaglutide, via PI3K/AKT pathway, reduced BNIP3 expression in the mitochondria, improving mitochondrial function. ConclusionSemaglutide ameliorates doxorubicin-induced mitochondrial and cardiac dysfunction via PI3K/AKT pathway, by reducing BNIP3 expression in mitochondria. The improvement in mitochondrial function reduces doxorubicin-mediated cardiac injury and improves cardiac function. Therefore, semaglutide is a potential therapy to reduce doxorubicin-induced acute cardiotoxicity.

Sex-related differences in delayed doxorubicin-induced cardiac dysfunction in C57BL/6 mice.

Cancer survivors may experience long-term cardiovascular complications due to chemotherapeutic drugs such as doxorubicin (DOX). The exact mechanism of delayed DOX-induced cardiotoxicity has not been fully elucidated. Sex is an important risk factor for DOX-induced cardiotoxicity. In the current study, we identified sex differences in delayed DOX-induced cardiotoxicity and determined the underlying molecular determinants of the observed sexual dimorphism. Five-week-old male and female mice were administered intraperitoneal injections of DOX (4mg/kg/week) or saline for 6weeks. Echocardiography was performed 5weeks after the last dose of DOX to evaluate cardiac function. Thereafter, mice were sacrificed and gene expression of markers of apoptosis, senescence, and inflammation was measured by PCR in hearts and livers. Proteomic profiling of the heart from both sexes was conducted to determine differentially expressed proteins (DEPs). Only DOX-treated male, but not female, mice demonstrated cardiac dysfunction, cardiac atrophy, and upregulated cardiac expression of Nppb and Myh7. No sex-related differences were observed in DOX-induced expression of most apoptotic, senescence, and pro-inflammatory markers. However, the gene expression of Trp53 was significantly reduced in hearts of DOX-treated female mice only. The anti-inflammatory marker Il-10 was significantly reduced in hearts of DOX-treated male mice only, while the pro-inflammatory marker Il-1α was significantly reduced in livers of DOX-treated female mice only. Gene expression of Tnf-α was reduced in hearts of both DOX-treated male and female mice. Proteomic analysis identified several DEPs after DOX treatment in a sex-specific manner, including anti-inflammatory acute phase proteins. This is the first study to assess sex-specific proteomic changes in a mouse model of delayed DOX-induced cardiotoxicity. Our proteomic analysis identified several sexually dimorphic DEPs, many of which are associated with the anti-inflammatory marker Il-10.

Aging-Associated ALKBH5-m6A Modification Exacerbates Doxorubicin-Induced Cardiomyocyte Apoptosis Via AT-Rich Interaction Domain 2.

Chemotherapy-induced cardiovascular disease is a growing concern in the elderly population who have survived cancer, yet the underlying mechanism remains poorly understood. We investigated the role of ALKBH5 (AlkB homolog 5), a primary N6-methyladenosine (m6A) demethylase, and its involvement in m6A methylation-mediated regulation of targets in aging-associated doxorubicin-induced cardiotoxicity. To validate the relationship between doxorubicin-induced cardiotoxicity and aging, we established young and old male mouse models. ALKBH5 expression was modulated through adeno-associated virus 9 (in vivo), Lentivirus, and siRNAs (in vitro) to examine its impact on cardiomyocyte m6A modification, doxorubicin-induced cardiac dysfunction, and remodeling. We performed mRNA sequencing, methylated RNA immunoprecipitation sequencing, and molecular assays to unravel the mechanism of ALKBH5-m6A modification in doxorubicin-induced cardiotoxicity. Our data revealed an age-dependent increase in doxorubicin-induced cardiac dysfunction, remodeling, and injury. ALKBH5 expression was elevated in aging mouse hearts, leading to reduced global m6A modification levels. Through mRNA sequencing and methylated RNA immunoprecipitation sequencing analyses, we identified ARID2 (AT-rich interaction domain 2) as the downstream effector of ALKBH5-m6A modulation in cardiomyocytes. Further investigations revealed that ARID2 modulates DNA damage response and enhances doxorubicin-induced cardiomyocyte apoptosis. Our findings provide insights into the role of ALKBH5-m6A modification in modulating doxorubicin-induced cardiac dysfunction, remodeling, and cardiomyocyte apoptosis in male mice. These results highlight the potential of ALKBH5-targeted treatments for elderly patients with cancer in clinical settings.

WGX50 mitigates doxorubicin-induced cardiotoxicity through inhibition of mitochondrial ROS and ferroptosis

BackgroundDoxorubicin (DOX)-induced cardiotoxicity (DIC) is a major impediment to its clinical application. It is indispensable to explore alternative treatment molecules or drugs for mitigating DIC. WGX50, an organic extract derived from Zanthoxylum bungeanum Maxim, has anti-inflammatory and antioxidant biological activity, however, its function and mechanism in DIC remain unclear.MethodsWe established DOX-induced cardiotoxicity models both in vitro and in vivo. Echocardiography and histological analyses were used to determine the severity of cardiac injury in mice. The myocardial damage markers cTnT, CK-MB, ANP, BNP, and ferroptosis associated indicators Fe2+, MDA, and GPX4 were measured using ELISA, RT-qPCR, and western blot assays. The morphology of mitochondria was investigated with a transmission electron microscope. The levels of mitochondrial membrane potential, mitochondrial ROS, and lipid ROS were detected using JC-1, MitoSOX™, and C11-BODIPY 581/591 probes.ResultsOur findings demonstrate that WGX50 protects DOX-induced cardiotoxicity via restraining mitochondrial ROS and ferroptosis. In vivo, WGX50 effectively relieves doxorubicin-induced cardiac dysfunction, cardiac injury, fibrosis, mitochondrial damage, and redox imbalance. In vitro, WGX50 preserves mitochondrial function by reducing the level of mitochondrial membrane potential and increasing mitochondrial ATP production. Furthermore, WGX50 reduces iron accumulation and mitochondrial ROS, increases GPX4 expression, and regulates lipid metabolism to inhibit DOX-induced ferroptosis.ConclusionTaken together, WGX50 protects DOX-induced cardiotoxicity via mitochondrial ROS and the ferroptosis pathway, which provides novel insights for WGX50 as a promising drug candidate for cardioprotection.Graphic abstract

Eupatilin attenuates doxorubicin-induced cardiotoxicity by activating the PI3K-AKT signaling pathway in mice.

Eupatilin is a pharmacologically active flavonoid with a variety of biological activities, such as anticancer, anti-inflammatory, antioxidant, neuroprotective, anti-allergic and cardioprotective effects. However, whether eupatilin has protective effects on doxorubicin-induced cardiotoxicity remains unknown. Thus, this study aimed to investigate the role of eupatilin in doxorubicin-induced cardiotoxicity. Mice were exposed to a single dose of doxorubicin (15mg/kg) to generate doxorubicin-induced cardiotoxicity or normal saline as a control. To explore the protective effects, mice were intraperitoneally injected with eupatilin daily for 7 days. Then, we examined the changes in cardiac function, inflammation, apoptosis, and oxidative stress to evaluate the effects of eupatilin on doxorubicin-induced cardiotoxicity. Additionally, RNA-seq analysis was introduced to explore the potential molecular mechanisms. Eupatilin ameliorated doxorubicin-induced cardiotoxicity by attenuating inflammation, oxidative stress, and cardiomyocyte apoptosis and ameliorated doxorubicin-induced cardiac dysfunction. Mechanistically, eupatilin activated the PI3K-AKT signaling pathway, as evidenced by RNA-seq analysis and Western blot analysis. This study provides the first evidence that eupatilin ameliorates doxorubicin-induced cardiotoxicity by attenuating inflammation, oxidative stress, and apoptosis. Pharmacotherapy with eupatilin provides a novel therapeutic regimen for doxorubicin-induced cardiotoxicity.

Astragaloside IV Inhibits NLRP3 Inflammasome-Mediated Pyroptosis via Activation of Nrf-2/HO-1 Signaling Pathway and Protects against Doxorubicin-Induced Cardiac Dysfunction.

Doxorubicin (DOX) is an effective broad-spectrum antitumor drug, but its clinical application is limited due to the side effects of cardiac damage. Astragaloside IV (AS-IV) is a significant active component of Astragalus membranaceus that exerts cardioprotective effects through various pathways. However, whether AS-IV exerts protective effects against DOX-induced myocardial injury by regulating the pyroptosis is still unknown and is investigated in this study. The myocardial injury model was constructed by intraperitoneal injection of DOX, and AS-IV was administered via oral gavage to explore its specific protective mechanism. Cardiac function and cardiac injury indicators, including lactate dehydrogenase (LDH), cardiac troponin I (cTnI), creatine kinase isoenzyme (CK-MB), and brain natriuretic peptide (BNP), and histopathology of the cardiomyocytes were assessed 4 weeks post DOX challenge. Serum levels of IL-1β, IL-18, superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione (GSH) and the expression of pyroptosis and signaling proteins were also determined. Cardiac dysfunction was observed after the DOX challenge, as evidenced by reduced ejection fraction, increased myocardial fibrosis, and increased BNP, LDH, cTnI, and CK-MB levels (p < 0.05, N = 3-10). AS-IV attenuated DOX-induced myocardial injury. The mitochondrial morphology and structure were also significantly damaged after DOX treatment, and these changes were restored after AS-IV treatment. DOX induced an increase in the serum levels of IL-1β, IL-18, SOD, MDA and GSH as well as an increase in the expression of pyroptosis-related proteins (p < 0.05, N = 3-6). Besides, AS-IV depressed myocardial inflammatory-related pyroptosis via activation of the expressions of nuclear factor E2-related factor 2 (Nrf-2) and heme oxygenase 1 (HO-1) (p < 0.05, N = 3). Our results showed that AS-IV had a significant protective effect against DOX-induced myocardial injury, which may be associated with the activation of Nrf-2/HO-1 to inhibit pyroptosis.

Combined Therapy of Low-Dose Angiotensin Receptor-Neprilysin Inhibitor and Sodium-Glucose Cotransporter-2 Inhibitor Prevents Doxorubicin-Induced Cardiac Dysfunction in Rodent Model with Minimal Adverse Effects.

Although cancer-therapy-related cardiac dysfunction (CTRCD) is a critical issue in clinical practice, there is a glaring lack of evidence regarding cardiotoxicity management. To determine an effective and suitable dosage of treatment using angiotensin receptor-neprilysin inhibitors (ARNI) with sodium-glucose cotransporter 2 inhibitors (SGLT2i), we adopted a clinically relevant rodent model with doxorubicin, which would mimic cardiac dysfunction in CTRCD patients. After the oral administration of drugs (vehicle, SGLT2i, ARNI, Low-ARNI/SGLT2i, ARNI/SGLT2i), several physiologic parameters, including hemodynamic change, cardiac function, and histopathology, were evaluated. Bulk RNA-sequencing was performed to obtain insights into the molecular basis of a mouse heart response to Low-ARNI/SGLT2i treatment. For the first time, we report that the addition of low-dose ARNI with SGLT2i resulted in greater benefits than ARNI, SGLT2i alone or ARNI/SGLT2i combination in survival rate, cardiac function, hemodynamic change, and kidney function against doxorubicin-induced cardiotoxicity through peroxisome proliferator-activated receptor signaling pathway. Low-dose ARNI with SGLT2i combination treatment would be practically beneficial for improving cardiac functions against doxorubicin-induced heart failure with minimal adverse effects. Our findings suggest the Low-ARNI/SGLT2i combination as a feasible novel strategy in managing CTRCD patients.

A circular RNA derived from the insulin receptor locus protects against doxorubicin-induced cardiotoxicity.

Cardiotoxicity leading to heart failure (HF) is a growing problem in many cancer survivors. As specific treatment strategies are not available, RNA discovery pipelines were employed and a new and powerful circular RNA (circRNA)-based therapy was developed for the treatment of doxorubicin-induced HF. The circRNA sequencing was applied and the highly species-conserved circRNA insulin receptor (Circ-INSR) was identified, which participates in HF processes, including those provoked by cardiotoxic anti-cancer treatments. Chemotherapy-provoked cardiotoxicity leads to the down-regulation of Circ-INSR in rodents and patients, which mechanistically contributes to cardiomyocyte cell death, cardiac dysfunction, and mitochondrial damage. In contrast, Circ-INSR overexpression prevented doxorubicin-mediated cardiotoxicity in both rodent and human cardiomyocytes in vitro and in a mouse model of chronic doxorubicin cardiotoxicity. Breast cancer type 1 susceptibility protein (Brca1) was identified as a regulator of Circ-INSR expression. Detailed transcriptomic and proteomic analyses revealed that Circ-INSR regulates apoptotic and metabolic pathways in cardiomyocytes. Circ-INSR physically interacts with the single-stranded DNA-binding protein (SSBP1) mediating its cardioprotective effects under doxorubicin stress. Importantly, in vitro transcribed and circularized Circ-INSR mimics also protected against doxorubicin-induced cardiotoxicity. Circ-INSR is a highly conserved non-coding RNA which is down-regulated during cardiotoxicity and cardiac remodelling. Adeno-associated virus and circRNA mimics-based Circ-INSR overexpression prevent and reverse doxorubicin-mediated cardiomyocyte death and improve cardiac function. The results of this study highlight a novel and translationally important Circ-INSR-based therapeutic approach for doxorubicin-induced cardiac dysfunction.

A Novel Locus on 6p21.2 for Cancer Treatment-Induced Cardiac Dysfunction Among Childhood Cancer Survivors.

Adult survivors of childhood cancer are at increased risk of cardiac late effects. Using whole-genome sequencing data from 1870 survivors of European ancestry in the St. Jude Lifetime Cohort (SJLIFE) study, genetic variants were examined for association with ejection fraction (EF) and clinically assessed cancer therapy-induced cardiac dysfunction (CCD). Statistically significant findings were validated in 301 SJLIFE survivors of African ancestry and 4020 survivors of European ancestry from the Childhood Cancer Survivor Study. All statistical tests were 2-sided. A variant near KCNK17 showed genome-wide significant association with EF (rs2815063-A: EF reduction = 1.6%; P = 2.1 × 10-8) in SJLIFE survivors of European ancestry, which replicated in SJLIFE survivors of African ancestry (EF reduction = 1.5%; P = .004). The rs2815063-A also showed a 1.80-fold (P = .008) risk of severe or disabling or life-threatening CCD and replicated in 4020 Childhood Cancer Survivor Study survivors of European ancestry (odds ratio = 1.40; P = .04). Notably, rs2815063-A was specifically associated among survivors exposed to doxorubicin only, with a stronger effect on EF (3.3% EF reduction) and CCD (2.97-fold). Whole blood DNA methylation data in 1651 SJLIFE survivors of European ancestry showed statistically significant correlation of rs2815063-A with dysregulation of KCNK17 enhancers (false discovery rate <5%), which replicated in 263 survivors of African ancestry. Consistently, the rs2815063-A was associated with KCNK17 downregulation based on RNA sequencing of 75 survivors. Leveraging the 2 largest cohorts of childhood cancer survivors in North America and survivor-specific polygenomic functional data, we identified a novel risk locus for CCD, which showed specificity with doxorubicin-induced cardiac dysfunction and highlighted dysregulation of KCNK17 as the likely molecular mechanism underlying this genetic association.

Mitochondrial Sirtuin-3 (SIRT3) Prevents Doxorubicin-Induced Dilated Cardiomyopathy by Modulating Protein Acetylation and Oxidative Stress.

High doses of doxorubicin put cancer patients at risk for developing dilated cardiomyopathy. Previously, we showed that doxorubicin treatment decreases SIRT3 (sirtuin 3), the main mitochondrial deacetylase and increases protein acetylation in rat cardiomyocytes. Here, we hypothesize that SIRT3 expression can attenuate doxorubicin induced dilated cardiomyopathy in vivo by preventing the acetylation of mitochondrial proteins. Nontransgenic, M3-SIRT3 (truncated SIRT3; short isoform), and M1-SIRT3 (full-length SIRT3; mitochondrial localized) transgenic mice were treated with doxorubicin for 4 weeks (8 mg/kg body weight per week). Echocardiography was performed to assess cardiac structure and function and validated by immunohistochemistry and immunofluorescence (n=4-10). Mass spectrometry was performed on cardiac mitochondrial peptides in saline (n=6) and doxorubicin (n=5) treated hearts. Validation was performed in doxorubicin treated primary rat and human induced stem cell derived cardiomyocytes transduced with adenoviruses for M3-SIRT3 and M1-SIRT3 and deacetylase deficient mutants (n=4-10). Echocardiography revealed that M3-SIRT3 transgenic mice were partially resistant to doxorubicin induced changes to cardiac structure and function whereas M1-SIRT3 expression prevented cardiac remodeling and dysfunction. In doxorubicin hearts, 37 unique acetylation sites on mitochondrial proteins were altered. Pathway analysis revealed these proteins are involved in energy production, fatty acid metabolism, and oxidative stress resistance. Increased M1-SIRT3 expression in primary rat and human cardiomyocytes attenuated doxorubicin-induced superoxide formation, whereas deacetylase deficient mutants were unable to prevent oxidative stress. Doxorubicin reduced SIRT3 expression and markedly affected the cardiac mitochondrial acetylome. Increased M1-SIRT3 expression in vivo prevented doxorubicin-induced cardiac dysfunction, suggesting that SIRT3 could be a potential therapeutic target for mitigating doxorubicin-induced dilated cardiomyopathy.

SIRT1 in the cardiomyocyte counteracts doxorubicin-induced cardiotoxicity via regulating histone H2AX.

Cardiotoxicity by doxorubicin predicts worse prognosis of patients. Accumulation of damaged DNA has been implicated in doxorubicin-induced cardiotoxicity. SIRT1, an NAD+-dependent histone/protein deacetylase, protects cells by deacetylating target proteins. We investigated whether SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating Ser139 phosphorylation of histone H2AX, a critical signal of the DNA damage response. Doxorubicin (5 mg/kg per week, x4) was administered to mice with intact SIRT1 (Sirt1f/f) and mice that lack SIRT1 activity in cardiomyocytes (Sirt1f/f;MHCcre/+). Reductions in left ventricular fractional shortening and ejection fraction by doxorubicin treatment were more severe in Sirt1f/f;MHCcre/+ than in Sirt1f/f. Myocardial expression level of type-B natriuretic peptide was 2.5-fold higher in Sirt1f/f;MHCcre/+ than in Sirt1f/f after doxorubicin treatment. Sirt1f/f;MHCcre/+ showed larger fibrotic areas and higher nitrotyrosine levels in the heart after doxorubicin treatment. Although doxorubicin-induced DNA damage evaluated by TUNEL staining was enhanced in Sirt1f/f;MHCcre/+, the myocardium from Sirt1f/f;MHCcre/+ showed blunted Ser139 phosphorylation of H2AX by doxorubicin treatment. In H9c2 cardiomyocytes, SIRT1 knockdown attenuated Ser139 phosphorylation of H2AX, increased DNA damage, and enhanced caspase-3 activation under doxorubicin treatment. Immunostaining revealed that acetylation level of H2AX at Lys5 was higher in hearts from Sirt1f/f;MHCcre/+. In H9c2 cells, acetyl-Lys5-H2AX level was increased by SIRT1 knockdown and reduced by SIRT1 overexpression. Ser139 phosphorylation in response to doxorubicin treatment was blunted in a mutant H2AX with substitution of Lys5 to Gln (K5Q) that mimics acetylated lysine compared with that in wild-type H2AX. Expression of K5Q-H2AX as well as S139A-H2AX, which cannot be phosphorylated at Ser139, augmented doxorubicin-induced caspase-3 activation. Treatment of mice with resveratrol, a SIRT1 activator, attenuated doxorubicin-induced cardiac dysfunction, which was associated with a reduction in acetyl-Lys5-H2AX level and a preserved phospho-Ser139-H2AX level. These findings suggest that SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating H2AX phosphorylation through its deacetylation in cardiomyocytes.

Sacubitril/valsartan reduces endoplasmic reticulum stress in a rat model of doxorubicin-induced cardiotoxicity.

The induction of endoplasmic reticulum (ER) stress has been reported as a key contributor to the cardiotoxicity of doxorubicin. Previous in vitro and in vivo studies suggest that sacubitril/valsartan, a novel angiotensin receptor-neprilysin inhibitor, could be effective against doxorubicin-induced cardiotoxicity. However, the precise mechanisms are not fully understood. Therefore, we investigated whether the cardioprotective effects of sacubitril/valsartan are associated with ER stress modulation in a rat model of doxorubicin-induced cardiotoxicity. Male Sprague-Dawley rats were treated with intraperitoneal injections of doxorubicin (15mg/kg; cumulative) or saline for 3weeks. From the day before the first treatment, control animals were gavaged daily with water (n = 8), whereas doxorubicin-treated animals were gavaged daily with water (n = 8) or sacubitril/valsartan (60mg/kg/day; n = 8) for 6weeks. Echocardiography was performed 6weeks after the initiation of doxorubicin. In addition, serum troponin I and N-terminal brain natriuretic peptide levels were determined, and the extent of apoptosis and protein levels related to ER stress in the cardiac tissue and doxorubicin-treated H9c2 cardiomyocytes were analyzed. Sacubitril/valsartan significantly reduced doxorubicin-induced cardiac dysfunction and apoptosis in the myocardium. In addition, sacubitril/valsartan significantly downregulated the expression levels of proteins related to apoptosis and ER stress, including BAX, caspase 3, GRP78, PERK, IRE-1α, ATF-6, eIF-2α, ATF-4, and CHOP, in the myocardium of a rat model of doxorubicin-induced cardiotoxicity in vivo and doxorubicin-treated H9c2 cardiomyocytes in vitro. Sacubitril/valsartan significantly alleviated doxorubicin-induced cardiotoxicity, which may be associated with the reduction of ER stress.

Salidroside inhibits doxorubicin-induced cardiomyopathy by modulating a ferroptosis-dependent pathway

BackgroundDoxorubicin-induced cardiotoxicity (DIC) limits the clinical application of the drug in treatment of cancers and imposes a severe health burden on the patients. Therefore, there is an urgent need to develop alternative therapeutic strategies or drugs to minimize DIC. Salidroside is a phenylpropanoid glycoside extracted from Rhodiola rosea with multiple biological effects such as anti-inflammation and antioxidant properties. However, its mechanism of action in DIC is still poorly understood. PurposeThe present study was aimed to investigate the role of salidroside in DIC and associated mechanism of action for the described effects. MethodsCardiac dysfunction was induced through treatment of mice with doxorubicin in vivo and in vitro. The mechanism of action of salidroside was investigated using western blot assay, qPCR, immunofluorescence, histochemistry, echocardiography, and high-content imaging system. ResultsResults of the current study found that treatment of mice with salidroside significantly improved doxorubicin-induced cardiac dysfunction, ferroptosis-like cell damage, and fibrosis in vivo. Further, it was noted that salidroside inhibited ferroptosis in vivo and in vitro by limiting iron accumulation, restoring GPX4-dependent antioxidant capacity, and preventing lipid peroxidation at the cellular or mitochondrial levels. Mechanistically, salidroside inhibited DOX-induced mitochondrial ROS, Fe2+, and lipid peroxidation as well as restored mitochondrial membrane potential by promoting mitochondrial biogenesis, improving mitochondrial iron-sulfur clusters, and restoring mitochondrial OXPHOS complexes, thereby improving mitochondrial function. In addition, AMPK is a key protein that coordinates mitochondria, metabolism, and ferroptosis. Therefore, it was found that compound C (CC), an AMPK inhibitor, disrupted the regulation of cellular lipid metabolism and mitochondrial function of salidroside as well as led to failure of the protective effect of salidroside against ferroptotic cell death. ConclusionsThe present study evidently demonstrated the cardioprotective effects of salidroside against doxorubicin-induced cardiomyopathy. Further, salidroside markedly down-regulated ferroptotic cell death by activating AMPK-dependent signaling pathways including regulating abnormal fatty acid metabolism and maintaining mitochondrial function. Therefore, salidroside is can be exploited to develop a novel medication for clinical DIC and salidroside may represent a novel treatment that improves recovery from DIC by targeting ferroptosis.

CIRBP-OGFR axis safeguards against cardiomyocyte apoptosis and cardiotoxicity induced by chemotherapy

Cold-inducible RNA-binding protein (CIRBP) is documented to be required for maintaining cardiac function, however, its role in chemotherapy-induced cardiotoxicity remains obscured. Herein, we report that CIRBP decreases cardiomyocyte apoptosis and attenuates cardiotoxicity through disrupting OGF-OGFR signal. CIRBP deficiency is involved in diverse chemotherapeutic agents induced cardiomyocyte apoptosis. Delivery of exogenous CIRBP to the mouse myocardium significantly mitigated doxorubicin-induced cardiac apoptosis and dysfunction. Specifically, OGFR was identified as a downstream core effector responsible for chemotherapy-induced cardiomyocyte apoptosis. CIRBP was shown to interact with OGFR mRNA and to repress OGFR expression by reducing mRNA stability. CIRBP-mediated cytoprotection against doxorubicin-induced cardiac apoptosis was demonstrated to largely involve OGFR repression by CIRBP. NTX as a potent antagonist of OGFR successfully rescued CIRBP ablation-rendered susceptibility to cardiac dyshomeostasis upon exposure to doxorubicin, whereas another antagonist ALV acting only on opioid receptors did not. Taken together, our results demonstrate that CIRBP confers myocardium resistance to chemotherapy-induced cardiac apoptosis and dysfunction by dampening OGF/OGFR axis, shedding new light on the mechanisms of chemo-induced cardiotoxicity and providing insights into the development of an efficacious cardioprotective strategy for cancer patients.

Targeting Oxidative Stress, NLRP3 Inflammasome, and Autophagy by Fraxetin to Combat Doxorubicin-Induced Cardiotoxicity.

Doxorubicin belongs to the class of anthracycline antibiotics that is widely used in the treatment protocols of a wide range of malignancies. The major deleterious effect of doxorubicin use is the possible occurrence of cardiotoxicity. This study aimed to delineate the possible effects of targeting oxidative stress, NLRP3 inflammasome, and autophagy by fraxetin on doxorubicin-induced cardiac dysfunction in rats. In a model of doxorubicin-induced cardiotoxicity, the effects of different doses of fraxetin were assessed by determination of biochemical, histopathological, immunohistochemical, and electron microscopic changes. Fraxetin, in a dose-dependent manner, was found to have the ability to mitigate the harmful effects of oxidative stress and inflammation on myocardial muscles with significant decrease in NLRP3 inflammasome, augmentation of autophagy, and amelioration of the apoptotic signaling pathways. In addition, fraxetin, in a dose-dependent manner, had the ability to combat the echocardiographic, histopathological, immunohistochemical, and electron microscopic changes induced by doxorubicin in cardiomyocytes. As a result, fraxetin may be put into consideration as a new adjuvant line of therapy on the way to mitigate doxorubicin-induced cardiotoxicity.

A quantitative systems pharmacology approach to predict the safe‐equivalent dose of doxorubicin in patients with cardiovascular comorbidity

Patients with cardiovascular comorbidity are less tolerant to cardiotoxic drugs and should be treated with reduced doses to prevent cardiotoxicity. However, the safe‐equivalent dose of antitumor drugs in patients with cardiovascular disease/risk is difficult to predict because they are usually excluded from clinical trials as a result of ethical considerations. In this study, a translational quantitative system pharmacology‐pharmacokinetic‐pharmacodynamic (QSP‐PK‐PD) model was developed based on preclinical study to predict the safe‐equivalence dose of doxorubicin in patients with or without cardiovascular disease. Virtual clinical trials were conducted to validate the translational QSP‐PK‐PD model. The model replicated several experimental and clinical observations: the left ventricular ejection fraction (LVEF) was reduced and the left ventricular end‐diastolic volume (LVEDV) was elevated in systolic dysfunction rats, the LVEF was preserved and LVEDV reduced in diastolic dysfunction rats, and patients with preexisting cardiovascular disease were more vulnerable to doxorubicin‐induced cardiac dysfunction than cardiovascular healthy patients. A parameter sensitivity analysis showed that doxorubicin‐induced cardiovascular dysfunction was mainly determined by the sensitivity of cardiomyocytes to cardiotoxic drugs and the baseline value of LVEDV, reflected in LVEF change percentage from the baseline. Blood pressure was the least sensitive factor affecting doxorubicin‐induced cardiotoxicity.