HDAC6 inhibition reverses long-term doxorubicin-induced cognitive dysfunction by restoring microglia homeostasis and synaptic integrity.

Breast cancer is the most common female malignancy in both the developed and developing world. Doxorubicin is one of the most commonly used chemotherapies for breast cancer. Unfortunately, up to 60% of survivors report long-term chemotherapy-induced cognitive dysfunction (CICD) characterized by deficits in working memory, processing speed and executive function. Currently, no therapeutic standard for treating CICD exists. Here, we hypothesized that treatment with a blood-brain barrier permeable histone deacetylase 6 (HDAC6) inhibitor can successfully reverse long-term doxorubicin-induced cognitive dysfunction. Methods: The puzzle box test and novel object/place recognition test were used to assess cognitive function following a therapeutic doxorubicin dosing schedule in female mice. Mitochondrial function and morphology in neuronal synaptosomes were evaluated using the Seahorse XF24 extracellular flux analyzer and transmission electron microscopy, respectively. Hippocampal postsynaptic integrity was evaluated using immunofluorescence. Hippocampal microglia phenotype was determined using advanced imaging techniques and single-nucleus RNA sequencing. Results: A 14-day treatment with a blood-brain barrier permeable HDAC6 inhibitor successfully reversed long-term CICD in the domains of executive function, working and spatial memory. No significant changes in mitochondrial function or morphology in neuronal synaptosomes were detected. Long-term CICD was associated with a decreased expression of postsynaptic PSD95 in the hippocampus. These changes were associated with decreased microglial ramification and alterations in the microglia transcriptome that suggest a stage 1 disease-associated microglia (DAM) phenotype. HDAC6 inhibition completely reversed these doxorubicin-induced alterations, indicating a restoration of microglial homeostasis. Conclusion: Our results show that decreased postsynaptic integrity and a neurodegenerative microglia phenotype closely resembling stage 1 DAM microglia contribute to long-term CICD. Moreover, HDAC6 inhibition shows promise as an efficacious pharmaceutical intervention to alleviate CICD and improve quality of life of breast cancer survivors.

The diuretic amiloride attenuates doxorubicin-induced chemobrain in rats: Behavioral and mechanistic study.

Cognitive impairment or "chemobrain" is a troublesome adverse effect which had been increasingly reported by cancer patients after doxorubicin (DOX) chemotherapy. Notably, Hypertension, a very common comorbidity in cancer patients, could pose a greater risk for negative cognitive outcomes. Amiloride (AML) is an antihypertensive, potassium-sparing diuretic that has been proven to be neuroprotective in different experimental models; this can be attributed to its ability to inhibit different ion transporters such as Na+/H+ exchanger (NHE), which upon excessive activation can result in intracellular cationic overload, followed by oxidative damage and cellular death. Accordingly, this study was designed to investigate the potential neuroprotective effect of AML against DOX-induced chemobrain and to elucidate possible underlying mechanisms. Briefly, Histopathological examination and neurobehavioral testing (Morris water maze, Y maze and passive avoidance test) showed that AML co-treatment (10 mg/kg/day) markedly attenuated DOX (2 mg/kg/week)-induced neurodegeneration and memory impairment after 4 weeks of treatments. We found that DOX administration up-regulated NHE expression and increased lactic acid content in the hippocampus which were markedly opposed by AML. Moreover, AML mitigated DOX-induced neuroinflammation and decreased hippocampal tumor necrosis factor-α level, nuclear factor kappa-B, and cyclooxygenase-2 expression. Additionally, AML counteracted DOX-induced hippocampal oxidative stress as indicated by normalized malondialdehyde and glutathione levels. Furthermore, AML halted DOX-induced hippocampal apoptosis as evidenced by decreased caspase-3 activity and lower cytochrome c immunoexpression. Our results in addition to the previously reported antitumor effects of AML and its ability to mitigate cancer resistance to DOX therapy could point toward possible new repositioning scenarios of the diuretic AML especially regarding hypertensive cancer patients.

Curcumin-coated gold nanoparticles attenuate doxorubicin-induced cardiotoxicity via regulating apoptosis in a mouse model.

Doxorubicin (DOX) is one of the most widely used chemotherapy agents; however, its nonselective effect causes cardiotoxicity. Curcumin (Cur), a well known dietary polyphenol, could exert a significant cardioprotective effect, but the biological application of this substance is limited by its chemical insolubility. To overcome this limitation, in this study, we synthesised gold nanoparticles based on Cur (Cur-AuNPs). Ultraviolet-visible (UV-Vis) absorbance spectroscopy and transmission electron microscopy (TEM) were performed for the characterisation of synthesised NPs, and Fourier transform infrared (FTIR) spectroscopy were applied to detect Cur on the surface of AuNPs. Its cytotoxicity effect on H9c2 cells was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The biological efficacy of Cur-AuNPs was assessed after acute cardiotoxicity induction in BALB/c mice with DOX injection. The serum biomarkers, myocardial histological changes, and cardiomyocyte apoptosis were then measured. The results revealed that the heart protection by Cur-AuNPs is more effective than Cur alone. Heart protective effect of Cur-AuNPs was evident both in the short-term (24 hours) and long-term (14 days) study. The results of Cur-AuNPs400 after 24 hours of toxicity induction displayed the reduction of the cardiac injury serum biomarkers (LDH, CK-MB, cTnI, ADT, and ALT) and apoptotic proteins (Bax and Caspase-3), as well as increase of Bcl-2 anti-apoptotic proteins without any sign of interfibrillar haemorrhage and intercellular spaces in the heart tissue microscopic images. Our long-term study signifies that Cur-AuNPs400 in DOX-intoxicated mice could successfully inhibit body and heart weight loss in comparison to DOX group.

SNX17 protects the heart from doxorubicin-induced cardiotoxicity by modulating LMOD2 degradation.

Anthracyclines including doxorubicin (DOX) are still the most widely used and efficacious antitumor drugs, although their cardiotoxicity is a significant cause of heart failure. Despite considerable efforts being made to minimize anthracycline-induced cardiac adverse effects, little progress has been achieved. In this study, we aimed to explore the role and underlying mechanism of SNX17 in DOX-induced cardiotoxicity. We found that SNX17 was downregulated in cardiomyocytes treated with DOX both in vitro and in vivo. DOX treatment combined with SNX17 interference worsened the damage to neonatal rat ventricular myocytes (NRVMs). Furthermore, the rats with SNX17 deficiency manifested increased susceptibility to DOX-induced cardiotoxicity (myocardial damage and fibrosis, impaired contractility and cardiac death). Mechanistic investigation revealed that SNX17 interacted with leiomodin-2 (LMOD2), a key regulator of the thin filament length in muscles, via its C-TERM domain and SNX17 deficiency exacerbated DOX-induced cardiac systolic dysfunction by promoting aberrant LMOD2 degradation through lysosomal pathway. In conclusion, these findings highlight that SNX17 plays a protective role in DOX-induced cardiotoxicity, which provides an attractive target for the prevention and treatment of anthracycline induced cardiotoxicity.

Shenmai injection improves doxorubicin cardiotoxicity via miR-30a/Beclin 1.

BACKGROUND: Shenmai Injection (SMI) has been widely used in the treatment of cardiovascular diseases and can reduce side effects when combined with chemotherapy drugs. However, the potential protective mechanism of SMI on the cardiotoxicity caused by anthracyclines has not been clear. METHODS: We used network pharmacology methods to collect the compound components in SMI and myocardial injury targets, constructed a 'drug-disease' target interaction network relationship diagram, and screened the core targets to predict the potential mechanism of SMI in treating cardiotoxicity of anthracyclines. In addition, the rat model of doxorubicin cardiotoxicity was induced by injecting doxorubicin through the tail vein. The rats were randomized in the model group, miR-30a agomir group, SMI low-dose group, SMI high-dose group，and the control group. The cardiac ultrasound was used to evaluate the structure and function of the rat heart. HE staining was used to observe the pathological changes of the rat myocardium. Transmission electron microscopy was used to observe myocardial autophagosomes. The expression of miR-30a and Beclin 1 mRNA in the rat myocardium was detected by RT-qPCR. Western Blot detected the expression of LC3-II/LC3-I and p62 protein. RESULTS: The network pharmacological analysis found that SMI could act synergistically through multiple targets and multiple pathways, which might exert a myocardial protective effect through PI3K-Akt signaling pathways and cancer microRNAs. In vivo, compared with the control group, the treatment group could improve the cardiac structure and function, and reduce myocardial pathological damage and the number of autophagosomes. The expression of miR-30a in the myocardium of rats in miR-30a agomir group and SMI group increased (P < 0.01)，Beclin 1 mRNA was decreased (P < 0.01)，LC3-Ⅱ/LC3-I protein was decreased (P < 0.01 or P < 0.05)，and p62 protein was increased (P < 0.01 or P < 0.05). CONCLUSIONS: SMI has the characteristics of multi-component, multi-target, and multi-pathway. It can inhibit myocardial excessive autophagy by regulating the expression of miR-30a/Beclin 1 and alleviate the myocardial injury induced by doxorubicin.

Calycosin attenuates doxorubicin-induced cardiotoxicity via autophagy regulation in zebrafish models.

Anthracyclines are highly effective chemotherapeutics for antineoplastic treatment. However, cumulative cardiotoxicity is the main side effect with poor prognosis. No mechanism-based therapy is currently available to reverse chronic anthracycline-induced cardiotoxicity (AIC) after the deterioration of cardiac function. Calycosin (CA) is the main compound extracted from the traditional Chinese medicine Astragalus, and it has diverse beneficial effects, including autophagy modulation, anti-inflammatory and anti-tumor effects. Autophagy dysregulation is an important pathological event in AIC. Our study demonstrated a cardioprotective effect of CA in a zebrafish embryonic AIC model. To assess the effect of CA on late-onset chronic AIC, adult zebrafish were treated with CA 28 days after doxorubicin (DOX) injection, at which point heart function was obviously impaired. The results demonstrated that DOX blocked autophagic activity in adult zebrafish 8 weeks post-injection, and CA treatment improved heart function and restored autophagy. Further in vitro experiments demonstrated that atg7, which encodes an E1-like activating enzyme, may play an essential role in the CA regulation of autophagy. In conclusion, we used a rapid pharmacological screening system in embryo-adult zebrafish in vivo and elucidated the mechanism of gene targeting in vitro.

Roflumilast Attenuates Doxorubicin-Induced Cardiotoxicity by Targeting Inflammation and Cellular Senescence in Cardiomyocytes Mediated by SIRT1.

BACKGROUND AND PURPOSE: Cardiotoxicity is an important side effect of the treatment of a malignant tumor with Doxorubicin. Currently, decreasing the dosage of Doxorubicin to alleviate the side effects on cardiac function is the common method to deal with the cardiotoxicity induced by Doxorubicin. The present study aims to investigate the therapeutic effects of Roflumilast on Doxorubicin-induced inflammation and cellular senescence, as well as the potential mechanism in H9c2 myocardial cells. METHODS: The injured cardiac cell model was established by incubation with 5 µmol/L Doxorubicin. MTT was used to evaluate the cell viability of treated H9c2 cardiac cells. The expression of 4-HNE was determined using an immunofluorescence assay. The gene expression levels of IL-17, IL-6, TNF-α, IL-4, PAI-1, p21, and SIRT1 were evaluated using qRT-PCR and the protein levels of Gpx4, PAI-1, p21, and SIRT1 were determined using Western blot analysis. Secretions of IL-17, IL-6, TNF-α, IL-4, CK-MB, and cTnI were measured using ELISA. Cellular senescence was assessed using SA-ß-Gal staining. Si-RNA technology was used to knockdown the expression of SIRT1 in H9c2 cardiac cells. RESULTS: Cell viability of H9c2 cardiac cells was significantly inhibited by Doxorubicin but rescued by Roflumilast. The upregulated 4-HNE and downregulated Gpx4 were reversed by Roflumilast. The secretions of IL-6 and IL-17 were promoted by Doxorubicin and suppressed by Roflumilast. The increased SA-ß-Gal staining induced by Doxorubicin was inhibited by Roflumilast. P21 and PAI-1 were significantly upregulated and SIRT1 was greatly downregulated by Doxorubicin, all of which were reversed by Roflumilast. The anti-senescent effect of Roflumilast was abolished by knocking down SIRT1. CONCLUSION: Roflumilast might attenuate Doxorubicin-induced inflammation and cellular senescence in cardiomyocytes by upregulating SIRT1.

Features of Myocardial Remodeling and Changes in the Blood Lipid Spectrum in Experimental Doxorubicin-Induced Cardiomyopathy and Atorvastatin Administration.

Structural myocardial reorganization and changes in the blood lipid spectrum in rats were studied after administration of a single sublethal dose of doxorubicin (15 mg/kg) alone and in combination with atorvastatin (20 mg/kg/day over 7 days). It was established that doxorubicin induced the development of dyslipidemia in experimental animals (the concentrations of total cholesterol, triglycerides, and VLDL increased by 2.2, 2.0, and 1.96 times, respectively; the atherogenic coefficient increased by 3.4 times by day 7 of the experiment). In animals with experimental anthracycline cardiomyopathy treated with atorvastatin, the concentrations of the main components of the blood lipid spectrum increased less markedly. Atorvastatin alone induces moderate myocardial remodeling in comparison with more pronounced changes in the structural organization of the myocardium in rats treated with doxorubicin alone. Course treatment with atorvastatin under conditions of doxorubicin-induced cardiomyopathy reduced the severity of myocardial remodeling: the decrease in the volume density of cardiomyocytes and the increase in the volume density of the connective tissue were less pronounced in the dynamics of the experiment.

Ulinastatin reduces myocardial injury induced by doxorubicin in SD rats.

OBJECTIVE: The aim of this study was to observe the protective effect of Ulinastatin on myocardial injury induced by doxorubicin (DOX) in rats. MATERIALS AND METHODS: 30 male Sprague Dawley (SD) rats were divided into control group, DOX group, and Ulinastatin group by random number table method. The control group was intraperitoneally injected with saline, while the DOX group and the Ulinastatin group were injected intraperitoneally with DOX (2 mg/kg) once every other day to establish an acute myocardial injury (AMI) model. In the Ulinastatin group, Ulinastatin (1500 IU/100 mg) was injected intraperitoneally once a day for 2 weeks after the model was established. The changes in cardiac structure were observed with a light microscope, the changes in cardiac function in rats were detected with biochemical kits, and expression of oxidative stress and inflammatory response-related factors were detected by Western blotting, enzyme-linked immunosorbent assay (ELISA), and quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). RESULTS: Myocardial tissues in the control group were neatly arranged and dense, with complete and clear structure. The myocardial tissues in the DOX group were disorderly arranged, the interstitial fibrosis was evident, and the myocardial transverse striations broke and disappeared. The structure of tissues in Ulinastatin group was dramatically relieved compared with DOX group. The serum SOD and GSH-Px levels of the DOX groups were significantly lower than those of the control group, while the levels of MDA and ROS were dramatically higher than those of the control group. The serum SOD and GSH-Px level of Ulinastatin group were higher than that of DOX group, and the levels of MDA and ROS were lower than those of DOX group. LDH, AST, ALT, and CK levels were dramatically higher than those in the control group, while the above-mentioned serum myocardial zymogram levels in the Ulinastatin group were decreased. The expressions of IL-1ß, IL-6, TNF-α, and iNOS in the DOX and Ulinastatin groups were dramatically higher than those in the control group, while the expressions of the above inflammatory factors in the Ulinastatin group were all inhibited. CONCLUSIONS: Ulinastatin intervention can reduce myocardial injury in rats with DOX. The protective effect may be due to the elimination of oxygen free radicals, enhanced antioxidant enzyme activity, reduced lipid peroxidation and inflammatory responses, and thus repaired myocardial injury.

Caffeic acid phenethyl ester counteracts doxorubicin-induced chemobrain in Sprague-Dawley rats: Emphasis on the modulation of oxidative stress and neuroinflammation.

Chemotherapy-induced cognitive dysfunction (chemobrain) is one of the major complaints for cancer patients treated with chemotherapy such as Doxorubicin (DOX). The induction of oxidative stress and neuroinflammation were identified as major contributors to such adverse effect. Caffeic acid phenethyl ester (CAPE) is a natural polyphenolic compound, that exhibits unique context-dependent antioxidant activity. It exhibits pro-oxidant effects in cancer cells, while it is a potent antioxidant and cytoprotective in normal cells. The present study was designed to investigate the potential neuroprotective effects of CAPE against DOX-induced cognitive impairment. Chemobrain was induced in Sprague Dawley rats via systemic DOX administration once per week for 4 weeks (2 mg/kg/week, i.p.). CAPE was administered at 10 or 20 µmol/kg/day, i.p., 5 days per week for 4 weeks. Morris water maze (MWM) and passive avoidance tests were used to assess learning and memory functions. Oxidative stress was evaluated via the colorimetric determination of GSH and MDA levels in both hippocampal and prefrontal cortex brain regions. However, inflammatory markers, acetylcholine levels, and neuronal cell apoptosis were assessed in the same brain areas using immunoassays including either ELISA, western blotting or immunohistochemistry. DOX produced significant impairment in learning and memory as indicated by the data generated from MWM and step-through passive avoidance tests. Additionally DOX-triggered oxidative stress as evidenced from the reduction in GSH levels and increased lipid peroxidation. Treatment with DOX resulted in neuroinflammation as indicated by the increase in NF-kB (p65) nuclear translocation in addition to boosting the levels of pro-inflammatory mediators (COX-II/TNF-α) along with the increased levels of glial fibrillary acid protein (GFAP) in the tested tissues. Moreover, DOX reduced acetylcholine levels and augmented neuronal cell apoptosis as supported by the increased active caspase-3 levels. Co-treatment with CAPE significantly counteracted DOX-induced behavioral and molecular abnormalities in rat brain tissues. Our results provide the first preclinical evidence for CAPE promising neuroprotective activity against DOX-induced neurodegeneration and memory deficits.

Adiponectin agonist ADP355 ameliorates doxorubicin-induced cardiotoxicity by decreasing cardiomyocyte apoptosis and oxidative stress.

Doxorubicin (DOX) is an anthracycline derivative and widely used as an anticancer drug. However, the severe cardiotoxicity of DOX limits its application. ADP355 is an adiponectin-based active peptide with anti-liver fibrosis and atherosclerosis properties. It remains unclear the effects and involved mechanisms of ADP355 in DOX-induced cardiotoxicity. C57BL/6J mice were intraperitoneally injected DOX once a week to induce heart failure while receiving ADP355 treatment daily for 4 weeks. At the end of experiment, blood and heart tissues were collected. We found that ADP355 markedly improved DOX-induced cardiac dysfunction and histopathological damage, and decreased serum creatine kinase, lactate dehydrogenase and hydroxybutyrate dehydrogenase levels. The anti-apoptotic activity of ADP355 was indicated by reduction in TUNEL-positive cells and cleaved caspase-3 expression, along with decreased BCL2-associated X protein/B cell lymphoma 2 (BAX/BCL2) levels in heart tissues. Additionally, ADP355 markedly increased DOX-decreased cell viability by reducing BAX/BCL2, but inhibited reactive oxygen species production in H9c2 cells. Mechanistically, ADP355 attenuated expression of DOX-reduced nuclear factor-erythroid 2-related factor 2 (Nrf2) and superoxide dismutase 2, as well as mRNA levels of Nrf2 downstream targets. Furthermore, ADP355 activated sirtuin 2 and its target genes. In conclusion, we demonstrate that ADP355 alleviates DOX-induced cardiotoxicity by inhibiting myocardial apoptosis and oxidative stress through Nrf2 and sirtuin 2 signaling pathways. These findings suggest that ADP355 can be a promising candidate for the treatment of cardiac dysfunction.

Fucoidan from Fucus vesiculosus attenuates doxorubicin-induced acute cardiotoxicity by regulating JAK2/STAT3-mediated apoptosis and autophagy.

Doxorubicin (DOX) is well-known for its potent antitumor activity but limited by its multiple and serious adverse effects. A major adverse effect is acute cardiotoxicity; yet, its mechanism has not been elucidated. Fucoidan is a multifunctional and nontoxic polysaccharide that is widely studied because of its favorable biological activities and safety. Hence, we proposed that fucoidan may play a protective role in DOX-induced acute cardiotoxicity without causing additional side effects. Sprague-Dawley rats were injected intraperitoneally with a single high dose of DOX to induce acute cardiac injury. Fucoidan was administered orally before DOX injection and AG490, a JAK2 inhibitor, was applied to verify the participation of the JAK2/STAT3 pathway. In vitro, H9C2 cells were treated with the same drugs at different concentrations and intervention times. in vivo and in vitro results demonstrated that DOX administration induced myocardial damage accompanied by acceleratory apoptosis and deficient autophagy in heart tissues or cells, which could be significantly improved by fucoidan supplement. AG490 partly abolished the cardioprotective effects of fucoidan, suggesting the involvement of JAK2 signaling. Additionally, western blotting revealed DOX-induced JAK2/STAT3 pathway activation, which was enhanced by fucoidan and weaken by AG490. Hence, fucoidan exerted a favorable effect on DOX-induced cardiotoxicity by enhancing autophagy and suppressing apoptosis in a JAK2/STAT3-dependent manner, which may provide a promising and novel therapeutic strategy against negative chemotherapy-induced effects.

Glycyrrhizin improved autophagy flux via HMGB1-dependent Akt/mTOR signaling pathway to prevent Doxorubicin-induced cardiotoxicity.

Doxorubicin (DOX) is one of the most effective and irreplaceable chemotherapeutic agents but its clinical use is limited due to its cardiotoxicity. Glycyrrhizin(GL) has been applied to liver disorders for long. However, little is known that if GL could be meaningful in attenuating cardiotoxicity. The aim of this study is to investigate the cardioprotective effects of GL in DOX-induced cardiotoxicity (DIC) and the underlying mechanism. Here, H9c2 cardiomyoblasts, Neonatal rat cardiomyocytes (NRCMs), and Rats were introduced as test models. A single dose of 20 mg/kg DOX (i.p.) was applied to induce acute cardiotoxicity in vivo, as reflected by growth inhibition, increased levels of AST and CK-MB, and reduction of SOD activity, while GL (25 or 50 mg/kg/d, 14 d, i.p.) could counteract these effects. Moreover, pre-incubation with GL (0.8 mM for 12 h) in H9c2 cells protected against DOX-induced cytotoxicity, oxidative stress and depolarization of mitochondrial membrane potential (MMP). Besides, Western blot analysis showed that DOX upregulated the expression of LC3 II and p62 whereas GL reversed that both in vitro and in vivo and improved the obstructed autophagy flux in DOX-treated H9c2 cells with an autophagy inhibitor Bafilomycin A1 (Baf A1, 50 nM, 2 h). It has been previously documented that High-mobility group box 1 (HMGB1) was involved in DIC. In our work, knockdown of HMGB1 significantly increased cell viability and LC3 II level in H9c2, suggesting HMGB1 was crucial in DOX-induced autophagy-triggering cell death. Intriguingly, GL is a direct inhibitor of HMGB1. We found that GL downregulated Akt/mTOR autophagy signaling pathway in DOX-treated H9c2 cells. More importantly, in non-silencing H9c2 cells (transfected with negative control siRNA) cells, the expression of phospho-Akt, phospho-mTOR, p62, and LC3 II was significantly decreased with GL pretreament compared to DOX alone. However, in H9c2/HMGB1－(transfected with HMGB1 siRNA) cells exposed to DOX, the expression of p-Akt, p-mTOR, p62, LC3 II had no statistical difference with or without GL, revealing that HMGB1 mediated the cardioprotective action of GL in DIC. Taken together, our findings demonstrate that improved autophagy flux via HMGB1-dependent Akt/mTOR signaling pathway might contribute to attenuate DIC and go a novel insight into the underlying mechanisms of GL's cardioprotective action. GL could be a potential candidate for the prevention of DIC.

Paeonol Reverses Adriamycin Induced Cardiac Pathological Remodeling through Notch1 Signaling Reactivation in H9c2 Cells and Adult Zebrafish Heart.

Adriamycin is a commonly prescribed chemotherapeutic drug for a wide range of cancers. Adriamycin causes cardiotoxicity as an adverse effect that limits its clinical application in cancer treatment. Several mechanisms have been proposed to explain the toxicity it causes in heart cells. Disruption of inherent cardiac repair mechanism is the least understood mechanism of Adriamycin-induced cardiotoxicity. Adriamycin induces pathological remodeling in cardiac cells by promoting apoptosis, hypertrophy, and fibrosis. We found that Adriamycin inhibited Notch1 in a time- and dose-dependent manner in H9c2 cells. We used Paeonol, a Notch1 activator, and analyzed the markers of apoptosis, hypertrophy, and fibrosis in H9c2 cells in vitro and in adult zebrafish heart in vivo as model systems to study Adriamycin-induced cardiotoxicity. Paeonol activated Notch1 signaling and expression of its downstream target genes effectively in the Adriamycin-treated condition in vitro and in vivo. Also we detected that Notch activation using Paeonol protected the cells from apoptosis, collagen deposition, and hypertrophy response using functional assays. We conclude that Adriamycin induced cardiotoxicity by promoting the pathological cardiac remodeling through inhibition of Notch1 signaling and that the Notch1 reactivation by Paeonol protected the cells and reversed the cardiotoxicity.

Discovery of 3,3'-pyrrolidinyl-spirooxindoles as cardioprotectant prohibitin ligands.

The scaffold proteins prohibitins-1 and 2 (PHB1/2) play many important roles in coordinating many cell signaling pathways and represent emerging targets in cardiology and oncology. We previously reported that a family of natural products derivatives, flavaglines, binds to PHB1/2 to exert cardioprotectant and anti-cancer effects. However, flavaglines also target the initiation factor of translation eIF4A, which doesn't contribute to cardioprotection and may even induce some adverse effects. Herein, we report the development of a convenient and robust synthesis of the new PHB2 ligand 2'-phenylpyrrolidinyl-spirooxindole, and its analogues. We discovered that these compounds displays cardioprotective effect against doxorubicin mediated cardiotoxicity and uncovered the structural requirement for this activity. We identified in particular some analogues that are more cardioprotectant than flavaglines. Pull-down experiments demonstrated that these compounds bind not only to PHB2 but also PHB1. These novel PHB ligands may provide the basis for the development of new drugs candidates to protect the heart against the adverse effects of anticancer treatments.

Electrical stimulation prevents doxorubicin-induced atrophy and mitochondrial loss in cultured myotubes.

Muscle contraction may protect against the effects of chemotherapy to cause skeletal muscle atrophy, but the mechanisms underlying these benefits are unclear. To address this question, we utilized in vitro modeling of contraction and mechanotransduction in C2C12 myotubes treated with doxorubicin (DOX; 0.2 µM for 3 days). Myotubes expressed contractile proteins and organized these into functional myofilaments, as electrical field stimulation (STIM) induced intracellular calcium (Ca2+) transients and contractions, both of which were prevented by inhibition of membrane depolarization. DOX treatment reduced myotube myosin content, protein synthesis, and Akt (S308) and forkhead box O3a (FoxO3a; S253) phosphorylation and increased muscle RING finger 1 (MuRF1) expression. STIM (1 h/day) prevented DOX-induced reductions in myotube myosin content and Akt and FoxO3a phosphorylation, as well as increases in MuRF1 expression, but did not prevent DOX-induced reductions in protein synthesis. Inhibition of myosin-actin interaction during STIM prevented contraction and the antiatrophic effects of STIM without affecting Ca2+ cycling, suggesting that the beneficial effect of STIM derives from mechanotransductive pathways. Further supporting this conclusion, mechanical stretch of myotubes recapitulated the effects of STIM to prevent DOX suppression of FoxO3a phosphorylation and upregulation of MuRF1. DOX also increased reactive oxygen species (ROS) production, which led to a decrease in mitochondrial content. Although STIM did not alter DOX-induced ROS production, peroxisome proliferator-activated receptor-γ coactivator-1α and antioxidant enzyme expression were upregulated, and mitochondrial loss was prevented. Our results suggest that the activation of mechanotransductive pathways that downregulate proteolysis and preserve mitochondrial content protects against the atrophic effects of chemotherapeutics.

Protective effects of dimethyl itaconate in mice acute cardiotoxicity induced by doxorubicin.

Doxorubicin (DOX) is an antitumor drug widely used in hematological tumors and various solid tumors. However, the cardiotoxicity elicited by DOX severely limits its clinical treatment. Dimethyl itaconate (DI), a common form of itaconate, is found many potential targets for prevent heart injury. Here we employed wild type and Nrf2 knockout mice and induced a cardiotoxicity model by administration of DOX to clarify the effects of DI. After treatment with DI, we found that it could effectively alleviate the cardiotoxicity by analyzing morphology, LDH levels and heart weight/body weight ratio changes. Meanwhile we demonstrated that RIP3, a key protein of necrosis, was significantly decreased in DI treated group. Further we observed that treatment with DI could suppress oxidative stress by altering Nrf2/HO-1. Compared with vehicle group, DI could increase the tissue SOD and GSH, and reduce MDA levels, then DHE staining revealed that the level of ROS in DI group reduced by half. Finally, transmission electron microscope (TEM) data showed that treatment with DI obviously decreased the mitochondrial damage. While Nrf2 was ablated in mice, the protective effects of DI were vanished and SOD, GSH, MDA became unchanged related to vehicle group. This report provides the evidence for the protective effects of DI treatment in cardiotoxicity induced by DOX. On mechanisms, DI could reduce the oxidative stress by altering Nrf2/HO-1 pathway and prevent mitochondrial from damage. Taken together, these findings of this paper will afford the new therapeutic targets in DOX related cardiotoxicity.

Protective effects of five compounds from Livistona chinensis R. Brown leaves against hypoxia/reoxygenation, H2O2, or adriamycin-induced injury in H9c2 cells.

Purpose: Discovering new antimyocardial ischemia drug candidates that are highly efficient, have low toxicity, and originate from natural products is a popular trend for new cardiovascular drug development at present. The ethanol extract of Livistona chinensis leaves showed a favorable antioxidant activity in our preliminary screening test. This study aims to screen out antioxidants from the herb leaves further and evaluate their efficacy in acute myocardial ischemia treatment at the cellular level. Materials and methods: Guided with online 1, 1-diphenyl-2-picrylhydrazyl (DPPH)-high-performance liquid chromatography (HPLC) screening, antioxidants were first separated and isolated from the ethanol extract of L. chinensis leaves by preparative-HPLC. Subsequently, offline DPPH approach was used to validate the free radical scavenging activity of the components. Ultimately, the resulting antioxidants were evaluated against the hypoxia/reoxygenation (H/R)-, H2O2-, or adriamycin (ADM)-induced injury in H9c2 cells to verify their cardioprotective effects in vitro. Results: Five antioxidant ingredients, namely, orientin, isoorientin, vitexin, isovitexin, and tricin, were quickly distinguished and isolated from L. chinensis leaves. The IC50 values of these ingredients were further examined by offline DPPH assay, as follows: 15.51±0.22, 6.64±0.38, 11.86±0.24, 8.89±0.66, and 31.86±0.24 µg/mL, respectively. Out of these ingredients, isoorientin showed the strongest antioxidation, which was equivalent to that of the positive control drug (vitamin C, IC50: 6.99±0.62 µg/mL). Using H/R-, H2O2-, and ADM-induced H9c2 cell injury models, the five ingredients had different extents of cardioprotective effects in vitro. In particular, isoorientin showed the strongest protection. All the five ingredients also showed insignificant cytotoxic effect to normal H9c2 cells. Conclusion: The ethanol extract of L. chinensis leaves contained five antioxidants with low cardiac cytotoxicity. Isoorientin possessed the strongest antioxidation, which can predominantly account for the myocardial protection effects within the extract.

Pyrroloquinoline quinine ameliorates doxorubicin-induced autophagy-dependent apoptosis via lysosomal-mitochondrial axis in vascular endothelial cells.

The cardiotoxicity of doxorubicin (DOX) limits its clinical use in the treatment of a variety of solid tumors and malignant hematologic disease. However, the mechanism by which it causes cardiotoxicity is not fully understood. Apoptosis has been regarded as one of mechanisms underlying the cardiotoxic effects of DOX. In our study, we found that treatment of human umbilical vein endothelial cells (HUVECs) with DOX induced autophagy and apoptosis in a dose- and time-dependent manner. Treatment with DOX induced autophagy at earlier time (3 h), then lysosomal membrane permeabilization (LMP) altered after treatment for 12 h which followed by the release of cathepsin D (CTSD). Lysosome-associated membrane proteins-1 and -2 (LAMP1 and LAMP2) were decreased in DOX-treated cells. Additionally, DOX induced the collapse of mitochondrial transmembrane potential, reduction of translocase of the outer mitochondrial membrane-20 (TOM-20), and release of cytochrome c. Furthermore, autophagy inhibitor 3-MA relieved DOX-induced apoptosis as assessed by the expression of cleaved caspase-3, cleaved caspase-9 and TUNEL assay. CTSD inhibitor, pepstatin A, upregulated TOM-20 and suppressed the mitochondria release of cytochrome c as well as apoptosis under DOX stress. Pyrroloquinoline quinine (PQQ), a new B vitamin, ameliorated aforementioned phenomenon. In conclusion, our results suggested that DOX-induced apoptosis was autophagy-dependent via lysosomal-mitochondrial axis. PQQ had an ability to protect cell from autophagy-dependent apoptosis induced by DOX via lysosomal-mitochondrial axis to some extent. This study provided new mechanistic insight toward understanding the pathogenesis of DOX-induced cardiotoxicity and the protection effect of PQQ.

Exenatide alleviates adriamycin-induced heart dysfunction in mice: Modulation of oxidative stress, apoptosis and inflammation.

BACKGROUND: Adriamycin (ADR) is an effective antineoplastic drug; the clinical application of ADR is limited due to fatal heart dysfunction. Exenatide has antioxidant, anti-apoptotic and anti-inflammatory properties. It can alleviate heart damage induced by ischaemia-reperfusion injury. Thus, we assumed that exenatide would produce protective effects on ADR-induced heart dysfunction. METHOD: Mice were treated with exenatide 1 h prior to every ADR treatment for 20 days. Left ventricular function and performance were assessed by echocardiography. Additionally, H9c2 cells were pretreated with exenatide followed by ADR, and intracellular reactive oxygen species (ROS) and cell viability, as well as the lactate dehydrogenase (LDH) and the creatine kinase MB (CK-MB), were subsequently measured. Flow cytometry and TUNEL staining were applied to assess the effect of exenatide on cardiac damage caused by ADR. Western blot and RT-PCR were performed to detect the effect of exenatide on apoptosis-related genes (Bcl-2 and Bax) and inflammation-related genes and/or proteins (tumour necrosis factor-α, interleukin-6, nuclear factor-κB, and p53). RESULT: Echocardiography showed that cardiac dysfunction caused by ADR was significantly improved by treatment with exenatide. ADR mice had harmful changes in the levels of ROS and CK-MB/LDH production, as well as the targeted apoptotic and inflammatory molecules, and these effects were also reversed by exenatide. In vitro, exenatide mitigated ADR-induced oxidative stress and CK-MB/LDH production, as well as Annexin V+/PI+ and TUNEL+ apoptosis in H9c2 cells. CONCLUSION: In conclusion, our research demonstrated the potential protective effects of exenatide on ADR-induced heart dysfunction through suppressing oxidative stress, apoptosis and inflammation.