Adriamycin-induced heart failure: mechanism and modulation

Anthracyclines induce early changes in left ventricular systolic and diastolic function: A single centre study

AIMS

2 dimensional (2D) strain analysis detects subclinical left ventricular (LV) systolic dysfunction. Our aim was to evaluate changes in LV systolic and diastolic function in breast cancer patients early after anthracycline chemotherapy, and to identify predisposing factors.

METHODS AND RESULTS

140 patients were assessed by detailed echocardiography before and within seven days post treatment. LV ejection fraction (LVEF), global longitudinal strain (GLS), strain rate and radial and circumferential strain were assessed. Additionally, left atrial volumes and LV diastolic parameters were evaluated. LVEF although reduced after treatment, remained within the normal range (60±3% vs. 59±3%, p = 0.04). Triplane GLS was significantly reduced after treatment (-20.0±1.6% vs. -19.1±1.8%, p<0.001). Subclinical LV dysfunction (>11% reduction in GLS compared to before therapy) occurred in 22% (29/135). Impaired diastolic function grade significantly increased from 46% to 57% (p<0.001) after treatment. Furthermore, diastolic dysfunction was more common in the subgroup group with reduced systolic GLS compared to those without changes in GLS (30% vs. 11%; p = 0.04). No risk factors or clinical parameters were associated with the development of subclinical LV dysfunction; however the percentage change in early diastolic strain rate and the E velocity were independent predictors of >11% reduction in GLS.

CONCLUSION

Twenty two percent of patients had subclinical LV dysfunction by GLS, whilst none had cardiotoxicity defined by LVEF, demonstrating that GLS is more sensitive for detection of subclinical LV systolic dysfunction immediately after anthracycline therapy. Diastolic dysfunction increased, particularly in the group with reduced GLS, demonstrating the close pathophysiological relationship between systolic and diastolic function.

Synthesis and Biological Evaluation of Danshensu and Tetramethylpyrazine Conjugates as Cardioprotective Agents

Myocardial ischemia is a primary cause of sudden death worldwide. Numerous active ingredients of traditional Chinese medicines including danshensu (DSS) and tetramethylpyrazine (TMP) have been widely used for the treatment of myocardial ischemia. To enhance their therapeutic efficacy and improve their drugability, in this work, we designed new DSS and TMP conjugates. Their water solubility and protective effects were studied in vitro and in experimental animal models. The new compounds demonstrated higher activities than the positive control agents acetylated danshensu and tetramethylpyrazine conjugate (ADTM) and salvianolic acid B (SAB) in preventing cells from oxidative insult. Among the new compounds, 14, bearing two glycine moieties, was more water soluble. In addition, compound 14 was much more potent in preventing cells from oxidative injury, at least 10- and 20-fold as potent as ADTM and SAB, respectively. The protective effects of compound 14 may be attributed to its anti-radical activity and anti-apoptotic activity. These results suggest that compound 14 is a promising candidate for the treatment of myocardial ischemia.

Antioxidant and antiapoptotic effects of sea cucumber and valsartan against doxorubicin-induced cardiotoxicity in rats: The role of low dose gamma irradiation

Doxorubicin (DOX) is a highly effective antineoplastic drug; however, the clinical use of DOX is limited by its dose dependent cardiotoxicity. This study was conducted to evaluate the cardioprotective effect of sea cucumber and valsartan against DOX-induced cardiotoxicity in rats. Also, the role of exposure to low dose γ radiation (LDR) on each of them was investigated, since LDR could suppress various reactive oxygen species-related diseases. Rats received DOX (2.5mg/kg, ip) in six equal injections over a period of 2weeks, sea cucumber (14.4mg/kg, p.o) and valsartan (30mg/kg, p.o) for 8 successive weeks. Exposure to LDR (0.5Gy) was performed one day prior to DOX. Results revealed that DOX administration elevated serum levels of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK-MB) and troponin-I as well as increased cardiac lipid peroxide content and myeloperoxidase (MPO) activity. Additionally, it increased cardiac expressions of iNOS and caspase-3, accompanied by reduction in cardiac total protein and glutathione (GSH) contents. Treatment with sea cucumber or valsartan improved the cardiotoxicity of DOX. Their adjuvant therapy with LDR offers an additional benefit to the cardioprotection of the therapeutic drugs. These results confirmed by histopathological examination. In conclusion, sea cucumber and valsartan alone or combined with LDR attenuated DOX-induced cardiotoxicity via their antioxidant and anti-apoptotic activities and thus might be useful in the treatment of human patients under doxorubicin chemotherapy.

Cytotoxic Effect of Thymus caramanicus Jalas on Human Oral Epidermoid Carcinoma KB Cells

Abstract Identifying new chemotherapeutic agents with fewer side effects is a major concern for scientists today. Thymus caramanicus Jalas (Lamiaceae family) is one of the species of Thymus that grows wild in different regions of Iran. Traditionally, leaves of this plant are used in the treatment of diabetes, arthritis and cancer. Here was investigated the cytotoxic property of Thymus caramanicus essential oil and extract in human oral epidermoid carcinoma KB cells. Cell viability was measured by MTT and neutral red assays. The cells were exposed to different concentrations of essential oil (0.05-1 µL/mL) and extract (25-150 µg/mL) for 24 h. Doxorubicin was used as anticancer control drug. The data showed that the essential oil (IC50=0.44 µL/mL) and extract (IC50=105 µg/mL) induce potent cytotoxic property. Surprisingly, cytotoxic effects of essential oil and extract of this plant on KB cancer cells were greater than those on normal gingival HGF1-PI1 cell line. In addition, Thymus caramanicus could potentiate the effect of doxorubicin in sub-effective concentrations. The results of the present study indicate that essential oils and extracts of Thymus caramanicus have potential anti-proliferative property on KB cells and can be used as pharmaceutical case study for oral cancer treatments.

Short-term and long-term models of doxorubicin-induced cardiomyopathy in rats: A comparison of functional and histopathological changes

OBJECTIVES

Doxorubicin (DXR), an anthracyclic antineoplastic agent, is one of the most commonly drug utilized to induce dilated cardiomyopathy (DCM) and heart failure (HF), but the well optimized protocol for cardiomyopathy induction leading to development of cardiac systolic dysfunction is unclear. This study aims to critically compare short-term and long-term DXR injection protocols for the induction of DCM in rats.

METHODS

Animals were allocated into 3 experimental groups: a ST (short-term DXR injection) group, in which animals received 6 intraperitoneal (i.p.) injections of DXR (2.5mg/kg per dose) over a period of 2 weeks (cumulative dose of 15mg/kg); a LT (long-term DXR injection) group in which animals received weekly i.p. injections of DXR (2mg/kg per dose) over a period of 9 weeks (cumulative dose of 18mg/kg); and a control group in which animals received an appropriate volume of 0.9% saline i.p. All animals were submitted to echocardiography analysis at baseline and after completion treatment. Afterwards, the hearts were collected for conventional light microscopy and collagen quantification.

RESULTS

Morphological myocardial analysis of both DXR-treated groups showed an identical pattern of swollen and vacuolated cardiomyocytes and disorganization of myofibrils. There was pronounced interstitial fibrosis in both groups of DXR-treated hearts as compared to controls, as assessed by the interstitial collagen volume fraction. There was no difference in interstitial fibrosis between the ST and LT groups. The echocardiography analysis of the LT group showed structural and functional findings compatible with DCM, including increased left ventricular systolic (5.02±0.96mm) and diastolic (7.68±0.96mm) dimensions and reduction of ejection fraction (69.40±8.51%) as compared to the ST group (4.10±0.89mm, 7.32±0.84, and 79.68±7.23%, respectively) and control group (4.07±0.72mm, 7.17±0.68mm and 80.08±4.71%, respectively), ANOVA p<0.01.

CONCLUSIONS

These results indicate that LT injection of DXR is more effective than ST injection in inducing left ventricular dysfunction and structural cardiac changes resembling those found in dilated cardiomyopathy.

Rutin attenuates doxorubicin-induced cardiotoxicity via regulating autophagy and apoptosis

Doxorubicin as anticancer agent can cause dose-dependent cardiotoxicity and heart failure in the long term. Rutin as a polyphenolic flavonoid has been illustrated to protect hearts from diverse cardiovascular diseases. Its function is known to be related to its antioxidant and antiinflammatory activity which may regulate multiple cellular signal pathways. However, the role of rutin on doxorubicin-induced cardiotoxicity has yet to be discovered. In this study, we explored the protective role of rutin on doxorubicin-induced heart failure and elucidated the potential mechanisms of protective effects of rutin against cardiomyocyte death. We analyzed cardiac tissues at the time point of 8weeks after doxorubicin treatment. The results by echocardiography, TUNEL staining, Masson's trichrome staining as well as Western blot analysis revealed that doxorubicin induced remarkable cardiac dysfunction and cardiotoxicity in mice hearts and cardiomyocytes, which were alleviated by rutin treatment. Western blot analysis indicated that the underlying mechanisms included inhibition excessive autophagy and apoptosis mediated by Akt activation. Collectively, our findings suggest that suppression of autophagy and apoptosis by administration of rutin could attenuate doxorubicin-induced cardiotoxicity, which enhances our knowledge to explore new drugs and strategies for combating this devastating side effect induced by doxorubicin. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure - edited by Jun Ren & Megan Yingmei Zhang.

Characterization and cardioprotective activity of anthocyanins from Nitraria tangutorum Bobr. by-products

Anthocyanins from the industrial by-products ofN. tangutorumjuice were composed of 16 anthocyanins derived from six anthocyanidins, and exerted an excellent protective effect on DOX-injury of H9c2 myoblast cells through multi-pathway.

Successful recovery and allogeneic stem cell transplant following chemotherapy-induced severe cardiomyopathy: literature review of management and prognostic factors

Chemotherapy-induced cardiomyopathy is one of the major possible hazards that can result from potential cardiotoxic agents while treating cancer. Prognostic risk factors include the rate of drug administration, history of hypertension, female gender, extremes of age, previous history of mediastinal irradiation, cumulative dose and pre-existing heart disease. Close monitoring of the patients, timely diagnosis, use of well-known biomarkers including cardiac troponins, NT-ProBNP and imaging studies like 2D Echo or cardiac MRI are essential. Emerging biomarkers include carbonyl reductases (CBR1 and CBR3), aldo-keto reductases (AKR, type 1A1, 1C3, 7A2) and topoisomerase2β (Top2β). β blockers and ACE inhibitors have not only been shown to slow down the progression of cardiac dysfunction but also produce symptomatic improvement. Our case report describes a patient with acute myeloblastic leukaemia who developed severe cardiomyopathy acutely after starting the anthracycline-based regimen. Nevertheless, with timely intervention her symptoms improved and subsequently she successfully received allogeneic stem cell transplantation.

Effects of doxorubicin on cardiac muscle subsarcolemmal and intermyofibrillar mitochondria

Doxorubicin (DOX) is a highly effective chemotherapeutic used in the treatment of a broad spectrum of malignancies. However, clinical use of DOX is highly limited by cumulative and irreversible cardiomyopathy that occurs following DOX treatment. The pathogenesis of DOX-induced cardiac muscle dysfunction is complex. However, it has been proposed that the etiology of this myopathy is related to mitochondrial dysfunction, as a result of the dose-dependent increase in the mitochondrial accumulation of DOX. In this regard, cardiac muscle possesses two morphologically distinct populations of mitochondria. Subsarcolemmal (SS) mitochondria are localized just below the sarcolemma, whereas intermyofibrillar (IMF) mitochondria are found between myofibrils. Mitochondria in both regions exhibit subtle differences in biochemical properties, giving rise to differences in respiration, lipid composition, enzyme activities and protein synthesis rates. Based on the heterogeneity of SS and IMF mitochondria, we hypothesized that acute DOX administration would have distinct effects on each cardiac mitochondrial subfraction. Therefore, we isolated SS and IMF mitochondria from the hearts of female Sprague-Dawley rats 48h after administration of DOX. Our results demonstrate that while SS mitochondria appear to accumulate greater amounts of DOX, IMF mitochondria demonstrate a greater apoptotic and autophagic response to DOX exposure. Thus, the divergent protein composition and function of the SS and IMF cardiac mitochondria result in differential responses to DOX, with IMF mitochondria appearing more susceptible to damage after DOX treatment.

Krüppel-like Factor 13 Is a Major Mediator of Glucocorticoid Receptor Signaling in Cardiomyocytes and Protects These Cells from DNA Damage and Death

Glucocorticoid receptor (GR) signaling has recently been shown to play a direct role in the regulation of cardiomyocyte function. In this study, we investigated the potential role of KLF13 as a downstream effector of GR action utilizing both in vivo and in vitro approaches. Our data show that KLF13 mRNA and protein levels are significantly diminished in the hearts of mice lacking GR in cardiomyocytes. Glucocorticoid administration up-regulated Klf13 mRNA in the mouse heart, in isolated primary cardiomyocytes, and in immortal cardiomyocyte cell lines. Glucocorticoid Klf13 gene expression was abolished by treatment with a GR antagonist (RU486) or by knockdown of GR in cardiomyocytes. Moreover, glucocorticoid induction of Klf13 mRNA was resistant to de novo protein synthesis inhibition, demonstrating that Klf13 is a direct glucocorticoid receptor gene target. A glucocorticoid responsive element (GRE) was identified in the Klf13 gene and its function was verified by chromatin immunoprecipitation in HL-1 cells and mouse hearts. Functional studies showed that GR regulation of Klf13 is critical to protect cardiomyocytes from DNA damage and cell death induced by cobalt(II) chloride hexahydrate (CoCl2·6H2O) and the antineoplastic drug doxorubicin. These results established a novel role for GR and KLF13 signaling in adult cardiomyocytes with potential clinical implications for the prevention of cardiotoxicity induced heart failure.

Protective effect of N-acetylcysteine, caffeic acid and vitamin E on doxorubicin hepatotoxicity

The aim of this study was to compare the possible protective effects of N-acetylcysteine (NAC), caffeic acid (CAPE) and vitamin E (Vit-E) on doxorubicin-induced hepatotoxicity. Thirty-two male Wistar albino rats, weighing between 250 and 350 g were supplied and randomly divided into five groups. Animals in study groups were pretreated with a single dose of doxorubicin (Dox), which was administered intraperitoneally (i.p.). Control group (Group I) was treated with intraperitoneal saline injection. Group II did not received any antioxidant agent after the injection. Group III and Group IV were given CAPE and intraperitoneal vitamin E injection for eight days, respectively. Group V received NAC for eight days. The study was finished after 10 days. Tissue samples were collected from all animals and histopathological examination was performed. There was statistically significant difference between the experiment groups and controls by means of mononuclear cell infiltration and diameters of hepatic sinusoid, terminal hepatic venule (central vein) and portal area (portal canal). Changes related with hepatocellular damage were more prominent, whereas there was no significant difference between Dox and NAC given groups histopathologically. It was observed that structural changes were regressed after CAPE administration. However, this recovery was more prominent in vitamin E given group. These findings suggest that Dox induced liver damage could be efficiently reversed by vitamin E administration. It has been found that CAPE, but not NAC has protective effects on Dox-induced hepatocellular damage. Human & Experimental Toxicology (2007) 26, 519—525

Protection against doxorubicin-induced myocardial dysfunction in mice by cardiac-specific expression of carboxyl terminus of hsp70-interacting protein

Carboxyl terminus of Hsp70-interacting protein (CHIP) is a critical ubiquitin ligase/cochaperone to reduce cardiac oxidative stress, inflammation, cardiomyocyte apoptosis and autophage etc. However, it is unclear whether overexpression of CHIP in the heart would exert protective effects against DOX-induced cardiomyopathy. Cardiac-specific CHIP transgenic (CHIP-TG) mice and the wild-type (WT) littermates were treated with DOX or saline. DOX-induced cardiac atrophy, dysfunction, inflammation, oxidative stress and cardiomyocyte apoptosis were significantly attenuated in CHIP-TG mice. CHIP-TG mice also showed higher survival rate than that of WT mice (40% versus 10%) after 10-day administration of DOX. In contrast, knockdown of CHIP by siRNA in vitro further enhanced DOX-induced cardiotoxic effects. Global gene microarray assay revealed that after DOX-treatment, differentially expressed genes between WT and CHIP-TG mice were mainly involved in apoptosis, atrophy, immune/inflammation and oxidative stress. Mechanistically, CHIP directly promotes ubiquitin-mediated degradation of p53 and SHP-1, which results in activation of ERK1/2 and STAT3 pathways thereby ameliorating DOX-induced cardiac toxicity.

Curcumin Downregulates Phosphate Carrier and Protects against Doxorubicin Induced Cardiomyocyte Apoptosis

Aim. To explore the effects of curcumin on phosphate carrier (PiC) and its role in protection against doxorubicin induced myocyte toxicity. Methods. Using H9c2 cell line, the cardiotoxic effect of doxorubicin and its mitigation by curcumin were studied. H9c2 cells were cultured with doxorubicin and/or curcumin at various concentrations. Analysis for apoptosis of H9c2 was done using flow cytometry. Confocal laser scanning microscopy was used to record the fluorescence intensity ratios and to determine the mitochondrial permeability transition pore (MPTP) opening state. Oxidative stress was measured using glutathione level, superoxide dismutase activities, and malondialdehyde content. The effect of doxorubicin and curcumin on PiC gene expression was measured by real-time PCR. Results. Curcumin decreased mRNA of PiC and was partly protective against oxidative stress, loss of mitochondrial transmembrane potential, and apoptosis induced by doxorubicin. Interestingly, the effect was not clearly dose dependent and the concentration of 12 mg/L was more efficient than 15 and 10 mg/L. Conclusion. Curcumin downregulates PiC and partly protects against doxorubicin induced oxidative stress and myocyte apoptosis.

Doxorubicin cardiotoxicity and target cells: a broader perspective

The cardiotoxicity of doxorubicin is becoming an interdisciplinary point of interest given a growing population of cancer survivors. The complex and not completely understood pathogenesis of this complication makes difficult to design successful preventive or curative measures. Although cardiomyocyte has been considered a classical cellular target, other cells including various types of undifferentiated cells are involved in myocardial homeostasis. Such perspective may shed light on previously unrecognized aspects of cardiotoxicity and promote new experimental and clinical cardioprotective strategies. In this review, different cellular targets of doxorubicin are discussed with the focus on cardiac progenitor cells, oxidative stress, DNA damage, senescence and apoptosis all of which contribute to their compromised functional properties.

Differential Regulation of Bcl-xL Gene Expression by Corticosterone, Progesterone, and Retinoic Acid

Corticosterone (CT), progesterone (PG), and retinoic acid (RA) are capable of inhibiting Doxorubicin (Dox) from inducing apoptosis in rat cardiomyocytes. Mechanistically, CT, PG, and RA induce increases of Bcl-xL protein and mRNA, and activate a 3.2 kb bcl-x gene promoter. CT and RA, but not PG, induced the activity of a 0.9 kb bcl-x promoter, containing sequences for AP-1 and NF-kB binding. RA, but not CT or PG, induced NF-kB activation. CT, but not PG or RA, induced AP-1 activation, and induction of the 0.9 kb bcl-x reporter by CT was inhibited by dominant negative c-Jun TAM-67 or removal of AP-1 binding site. Therefore, although CT, PG, and RA all induce Bcl-xL mRNA and protein, three independent mechanisms are in operation: while CT induces Bcl-xL via AP-1 transcription factor, and RA induces NF-kB activation and bcl-x promoter activity, PG induces Bcl-xL via a mechanism independent of NF-kB or AP-1.

Protective effect of Sheng-Mai Yin, a traditional Chinese preparation, against doxorubicin-induced cardiac toxicity in rats

Background

Sheng-Mai Yin (SMY), a modern Chinese formula based on Traditional Chinese Medicine theory, has been used to treat cardiovascular diseases in Eastern Asia. Our study focuses on the cardioprotection of SMY against doxorubicin (DOX)-induced cardiac toxicity in vivo.

Methods

Rats were injected with DOX (2.5 mg/kg) in six injections over a 2-week period. SMY was administrated intragastrically at the dose of 8.35, 16.7 and 33.4 g/kg, or 16.7 g/kg only twice a day concurrently with DOX for the 2-weeks. A series of assays were performed to detect the effects of SMY on: (i) heart weight index (HWI) and left ventricular mass index (LVMI); (ii) cardiac function; (iii) heart tissue morphology; (iv) the contents of carboxy terminal propeptide of procollagen typeI (PICP), amino terminal propeptide of procollagen type III (PШNP), transforming growth factor-β1 (TGF-β1), B-type natriuretic peptide (BNP), monocyte chemoattractant protein-1 (MCP-1), interferon gamma (INF-γ) and interleukin 6 (IL-6) by ELISA; (v) the mRNA levels of TGF-β1 and toll-like receptor-2 (TLR2); and (vi) protein level of TGF-β1.

Results

Rats treated with SMY displayed the reductions of BNP and CK-MB increased by DOX in a dose-dependent manner. Moderate dose of SMY exhibited the correction for the increased HWI, LVMI, and the injured cardiac function, as well as the collagen accumulation. In addition, cardioprotection of SMY against DOX-induced cardiac toxicity was demonstrated by the reduction of myocardial fibrosis, characterized by the suppression of PICP, PШNP and TGF-β1, as well as the anti-inflammation and the regulation for cardiac immune microenvironment, characterized by the inhibition of TLR2, MCP-1, INF-γ and IL-6.

Conclusions

SMY may protect heart function through the restriction of myocardial fibrosis induced by DOX, which suggests the potentially therapeutic effect of SMY on DOX-induced cardiomyopathy.

Increase of miR-199a-5p by protoporphyrin IX, a photocatalyzer, directly inhibits E2F3, sensitizing mesenchymal tumor cells to anti-cancer agents

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths. Protoporphyrin IX (PPIX) has been used for photodynamic therapy. Mesenchymal cancer cells adapt to tumor microenvironments for growth and metastasis possibly in association with miRNA dysregulation. In view of the effect of PPIX on cancer-related genes, and its potential to inhibit tumor growth and migration/invasion, this study investigated whether PPIX enables mesenchymal liver tumor to restore dysregulated miRNAs, and if so, whether it sensitizes the cancer cells to chemotherapy. In addition, we explored new target(s) of the miRNA(s) that contribute to the anti-cancer effects. Of the ten miRNAs predicted by the 3′-UTR of HIF-1α mRNA, PPIX treatment increased miR-199a-5p, leading to the inhibition of E2F3 expression which is upregulated in mesenchymal liver tumor. miR-199a-5p levels were downregulated in HCC with E2F3 overexpression. An approach modulating epithelial-mesenchymal transition provided the expected changes in miR-199a-5p and E2F3 in vivo. PPIX prevented tumor cell growth and migration/invasion, and had a synergistic anti-cancer effect when combined with chemotherapeutics. In a xenograft model, PPIX treatment decreased overall growth and average tumor volume, which paralleled E2F3 inhibition. Overall, PPIX inhibited growth advantage and migratory ability of cancer cells and sensitized mesenchymal liver tumor cells to chemotherapeutics.

SIRT1 activation attenuates diastolic dysfunction by reducing cardiac fibrosis in a model of anthracycline cardiomyopathy

BACKGROUND

Doxorubicin (DOXO) is an effective anti-neoplastic drug but its clinical benefits are hampered by cardiotoxicity. Oxidative stress, apoptosis and myocardial fibrosis mediate the anthracycline cardiomyopathy. ROS trigger TGF-β pathway that activates cardiac fibroblasts promoting fibrosis. Myocardial stiffness contributes to diastolic dysfunction, less studied aspect of anthracycline cardiomyopathy. Considering the role of SIRT1 in the inhibition of the TGF-β/SMAD3 pathway, resveratrol (RES), a SIRT1 activator, might improve cardiac function by interfering with the development of cardiac fibrosis in a model of DOXO-induced cardiomyopathy.

METHODS

F344 rats received a cumulative dose of 15 mg/kg of DOXO in 2 weeks or DOXO+RES (DOXO and RES, 2.5mg/kg/day, concomitantly for 2 weeks and then RES alone for 1 more week). The effects of RES on cardiac fibroblasts were also tested in vitro.

RESULTS

Along with systolic dysfunction, DOXO was also responsible of diastolic abnormalities. Myocardial stiffness correlated with fibroblast activation and collagen deposition. DOXO+RES co-treatment significantly improved ± dP/dt and, more interestingly, ameliorated end-diastolic pressure/volume relationship. Treatment with RES resulted in reduced fibrosis and fibroblast activation and, most importantly, the mortality rate was significantly reduced in DOXO+RES group. Fibroblasts isolated from DOXO+RES-treated rats, in which SIRT1 was upregulated, showed decreased levels of TGF-β and pSMAD3/SMAD3 when compared to cells isolated from DOXO-exposed hearts.

CONCLUSIONS

Our findings reveal a key role of SIRT1 in supporting animal survival and functional parameters of the heart. SIRT1 activation by interfering with fibrogenesis can improve relaxation properties of myocardium and attenuate myocardial remodeling related to chemotherapy.

Hypothalamic energy metabolism is impaired by doxorubicin independently of inflammation in non-tumour-bearing rats

We sought to explore the effects of doxorubicin on inflammatory profiles and energy metabolism in the hypothalamus of rats. To investigate these effects, we formed two groups: a control (C) group and a Doxorubicin (DOXO) group. Sixteen rats were randomly assigned to either the control (C) or DOXO groups. The hypothalamus was collected. The levels of interleukin (IL)-1β, IL-6, IL-10, TNF-α and energy metabolism (malate dehydrogenase, complex I and III activities) were analysed in the hypothalamus. The DOXO group exhibited a decreased body weight (p < 0.01). Hypothalamic malate dehydrogenase activity was reduced when compared with control (p < 0.05). In addition, pro-inflammatory cytokine levels were unchanged. Therefore, our results demonstrate that doxorubicin leads to an impairment of \hypothalamic energy metabolism, but do not affect the inflammatory pathway. SIGNIFICANCE PARAGRAPH: The hypothalamus is a central organ that regulates a great number of functions, such as food intake, temperature and energy expenditure, among others. Doxorubicin can lead to deep anorexia and metabolic chaos; thus, we observed the effect of this chemotherapeutic drug on the inflammation and metabolism in rats after the administration of doxorubicin in order to understand the central effect in the hypothalamus. Drug treatment by doxorubicin is used as a cancer therapy; however the use of this drug may cause harmful alterations to the metabolism. Thus, further investigations are needed on the impact of drug therapy over the long term.

Epigallocatechin-3-gallate pretreatment attenuates doxorubicin-induced cardiotoxicity in rats: A mechanistic study

Doxorubicin (DOX) is a widely used chemotherapeutic agent however its clinical use is limited by cumulative cardiotoxicity. Epigallocatechin-3-gallate (EGCG), a main catechin in green tea, possesses a potent antioxidant, anti-apoptotic and anticancer properties. The current study aimed to investigate the potential protective effect of EGCG against DOX-induced cardiotoxicity. Firstly the potential cardioprotective dose of EGCG was screened at different doses (10, 20 and 40 mg/kg/day) against a single dose of DOX (15 mg/kg; i.p.). EGCG protected against DOX-induced ECG changes, leakage of cardiac enzymes (creatine kinase isoenzyme-MB, and lactate dehydrogenase) and histopathological changes. The dose of 40 mg/kg EGCG was selected for further assessment to address the EGCG cardioprotective mechanisms. EGCG was given orally 3 times/week for 4 consecutive weeks and DOX (2.5 mg/kg; i.p.) 3 times/week on the last 2 weeks. EGCG significantly ameliorated oxidative stress injury evoked by DOX as evidenced by inhibition of reduced glutathione depletion and lipid peroxidation as well as elevation of antioxidant enzyme activities. DOX caused down-regulation of ErbB2 expression while EGCG pretreatment significantly increased ErbB2 expression indicating its effect on pro-survival pathway. Furthermore, DOX provoked apoptotic responses evidenced by increasing the expression of nuclear factor kappa-B, tumor suppressor protein p53, calpain 2, caspases 3 and 12. Additionally basal level of Hsp70 was reduced in DOX-intoxicated group. EGCG pretreatment significantly ameliorated these apoptotic signals indicating its anti-inflammatory and anti-apoptotic actions. In conclusion, EGCG possesses cardioprotective action against DOX-induced cardiotoxicity by suppressing oxidative stress, inflammation and apoptotic signals as well as activation of pro-survival pathways.

A Novel Angiotensin Type I Receptor Antagonist, Fimasartan, Prevents Doxorubicin-induced Cardiotoxicity in Rats

Angiotensin receptor blockers (ARBs) have organ-protective effects in heart failure and may be also effective in doxorubicin-induced cardiomyopathy (DOX-CMP); however, the efficacy of ARBs on the prevention of DOX-CMP have not been investigated. We performed a preclinical experiment to evaluate the preventive effect of a novel ARB, fimasartan, in DOX-CMP. All animals underwent echocardiography and were randomly assigned into three groups: treated daily with vehicle (DOX-only group, n=22), 5 mg/kg of fimasartan (Low-fima group, n=22), and 10 mg/kg of fimasartan (High-fima group, n=19). DOX was injected once a week for six weeks. Echocardiography and hemodynamic assessment was performed at the 8th week using a miniaturized conductance catheter. Survival rate of the High-fima group was greater (100%) than that of the Low-fima (75%) and DOX-only groups (50%). Echocardiography showed preserved left ventricular (LV) ejection fraction in the High-fima group, but not in the DOX-only group (P=0.002). LV dimensions increased in the DOX-only group; however, remodeling was attenuated in the Low-fima and High-fima groups. Hemodynamic assessment showed higher dP/dt in the High-fima group compared with the DOX-only group. A novel ARB, fimasartan, may prevent DOX-CMP and improve survival rate in a dose-dependent manner in a rat model of DOX-CMP and could be a treatment option for the prevention of DOX-CMP.

Mitochondrial dynamics: Orchestrating the journey to advanced age

Aging is a degenerative process that unfortunately is an inevitable part of life and risk factor for cardiovascular disease including heart failure. Among the several theories purported to explain the effects of age on cardiac dysfunction, the mitochondrion has emerged a central regulator of this process. Hence, it is not surprising that abnormalities in mitochondrial quality control including biogenesis and turnover have such detrimental effects on cardiac function. In fact mitochondria serve as a conduit for biological signals for apoptosis, necrosis and autophagy respectively. The removal of damaged mitochondria by autophagy/mitophagy is essential for mitochondrial quality control and cardiac homeostasis. Defects in mitochondrial dynamism fission/fusion events have been linked to cardiac senescence and heart failure. In this review we discuss the impact of aging on mitochondrial dynamics and senescence on cardiovascular health. This article is part of a Special Issue entitled: CV Aging.

Gαq protein carboxyl terminus imitation polypeptide GCIP-27 improves cardiac function in chronic heart failure rats

Background

Gαq protein carboxyl terminus imitation polypeptide (GCIP)-27 has been shown to alleviate pathological cardiomyocyte hypertrophy induced by various factors. Pathological cardiac hypertrophy increases the morbidity and mortality of cardiovascular diseases while it compensates for poor heart function. This study was designed to investigate the effects of GCIP-27 on heart function in rats with heart failure induced by doxorubicin.

Methods and Results

Forty-eight rats were randomly divided into the following six groups receiving vehicle (control), doxorubicin (Dox), losartan (6 mg/kg, i.g.) and three doses of GCIP-27 (10, 30, 90 μg/kg; i.p., bid), respectively. Heart failure was induced by Dox, which was administered at a 20 mg/kg cumulative dose. After 10 weeks of treatment, we observed that GCIP-27 (30, 90 μg/kg) significantly increased ejection fraction, fraction shortening, stroke volume and sarcoplasmic reticulum Ca²⁺ ATPase activity of Dox-treated hearts. Additionally, GCIP-27 decreased myocardial injury, heart weight index and left ventricular weight index, fibrosis and serum cardiac troponin-I concentration in Dox-treated mice. Immunohistochemistry, western blotting and real-time PCR experiments indicated that GCIP-27 (10–90 μg/kg) could markedly upregulate the protein expression of myocardial α-myosin heavy chain (MHC), Bcl-2, protein kinase C (PKC) ε and phosphorylated extracellular signal-regulated kinase (p-ERK) 1/2 as well as the mRNA expression of α-MHC, but downregulated the expression of β-MHC, Bax and PKC βII, and the mRNA expression levels of β-MHC in Dox-treated mice. It was also found that GCIP-27 (30, 90 μg/L) decreased cell size and protein content of cardiomyocytes significantly in vitro by comparison of Dox group.

Conclusions

GCIP-27 could effectively ameliorate heart failure development induced by Dox. PKC–ERK1/2 signaling might represent the underlying mechanism of the beneficial effects of GCIP-27.

Increased mitochondrial emission of reactive oxygen species and calpain activation are required for doxorubicin-induced cardiac and skeletal muscle myopathy

Although doxorubicin (DOX) is a highly effective anti-tumour agent used to treat a variety of cancers, DOX administration is associated with significant side effects, including myopathy of both cardiac and skeletal muscles. The mechanisms responsible for DOX-mediated myopathy remain a topic of debate. We tested the hypothesis that both increased mitochondrial reactive oxygen species (ROS) emission and activation of the cysteine protease calpain are required for DOX-induced myopathy in rat cardiac and skeletal muscle. Cause and effect was determined by administering a novel mitochondrial-targeted anti-oxidant to prevent DOX-induced increases in mitochondrial ROS emission, whereas a highly-selective pharmacological inhibitor was exploited to inhibit calpain activity. Our findings reveal that mitochondria are a major site of DOX-mediated ROS production in both cardiac and skeletal muscle fibres and the prevention of DOX-induced increases in mitochondrial ROS emission protects against fibre atrophy and contractile dysfunction in both cardiac and skeletal muscles. Furthermore, our results indicate that DOX-induced increases in mitochondrial ROS emission are required to activate calpain in heart and skeletal muscles and, importantly, calpain activation is a major contributor to DOX-induced myopathy. Taken together, these findings show that increased mitochondrial ROS production and calpain activation are significant contributors to the development of DOX-induced myopathy in both cardiac and skeletal muscle fibres.

Profiling of skeletal muscle Ankrd2 protein in human cardiac tissue and neonatal rat cardiomyocytes

Muscle-specific mechanosensors Ankrd2/Arpp (ankyrin repeat protein 2) and Ankrd1/CARP (cardiac ankyrin repeat protein) have an important role in transcriptional regulation, myofibrillar assembly, cardiogenesis and myogenesis. In skeletal muscle myofibrils, Ankrd2 has a structural role as a component of a titin associated stretch-sensing complex, while in the nucleus it exerts regulatory function as transcriptional co-factor. It is also involved in myogenic differentiation and coordination of myoblast proliferation. Although expressed in the heart, the role of Ankrd2 in the cardiac muscle is completely unknown. Recently, we have shown that hypertrophic and dilated cardiomyopathy pathways are altered upon Ankrd2 silencing suggesting the importance of this protein in cardiac tissue. Here we provide the underlying basis for the functional investigation of Ankrd2 in the heart. We confirmed reduced Ankrd2 expression levels in human heart in comparison with Ankrd1 using RNAseq and Western blot. For the first time we demonstrated that, apart from the sarcomere and nucleus, both proteins are localized to the intercalated disks of human cardiomyocytes. We further tested the expression and localization of endogenous Ankrd2 in rat neonatal cardiomyocytes, a well-established model for studying cardiac-specific proteins. Ankrd2 was found to be expressed in both the cytoplasm and nucleus, independently from maturation status of cardiomyocytes. In contrast to Ankrd1, it is not responsive to the cardiotoxic drug Doxorubicin, suggesting that different mechanisms govern their expression in cardiac cells.

Bnip3 mediates doxorubicin-induced cardiac myocyte necrosis and mortality through changes in mitochondrial signaling

Doxorubicin (DOX) is widely used for treating human cancers, but can induce heart failure through an undefined mechanism. Herein we describe a previously unidentified signaling pathway that couples DOX-induced mitochondrial respiratory chain defects and necrotic cell death to the BH3-only protein Bcl-2-like 19 kDa-interacting protein 3 (Bnip3). Cellular defects, including vacuolization and disrupted mitochondria, were observed in DOX-treated mice hearts. This coincided with mitochondrial localization of Bnip3, increased reactive oxygen species production, loss of mitochondrial membrane potential, mitochondrial permeability transition pore opening, and necrosis. Interestingly, a 3.1-fold decrease in maximal mitochondrial respiration was observed in cardiac mitochondria of mice treated with DOX. In vehicle-treated control cells undergoing normal respiration, the respiratory chain complex IV subunit 1 (COX1) was tightly bound to uncoupling protein 3 (UCP3), but this complex was disrupted in cells treated with DOX. Mitochondrial dysfunction induced by DOX was accompanied by contractile failure and necrotic cell death. Conversely, shRNA directed against Bnip3 or a mutant of Bnip3 defective for mitochondrial targeting abrogated DOX-induced loss of COX1-UCP3 complexes and respiratory chain defects. Finally, Bnip3(-/-) mice treated with DOX displayed relatively normal mitochondrial morphology, respiration, and mortality rates comparable to those of saline-treated WT mice, supporting the idea that Bnip3 underlies the cardiotoxic effects of DOX. These findings reveal a new signaling pathway in which DOX-induced mitochondrial respiratory chain defects and necrotic cell death are mutually dependent on and obligatorily linked to Bnip3 gene activation. Interventions that antagonize Bnip3 may prove beneficial in preventing mitochondrial injury and heart failure in cancer patients undergoing chemotherapy.

Development of poly (I:C) modified doxorubicin loaded magnetic dendrimer nanoparticles for targeted combination therapy

The objective of this study was to develop and evaluate the anticancer activity and the safety of a combinational drug delivery system using polyamidoamine (PAMAM) dendrimer-coated iron oxide nanoparticles for doxorubicin and poly I:C delivery in vitro. Dendrimer-coated magnetic nanoparticles (DcMNPs) are suitable for drug delivery system as nanocarriers with their following properties, such as surface functional groups, symmetry perfection, internal cavities, nano-size and magnetization. These nanoparticles could be targeted to the tumor site under a magnetic field since they have a magnetic core. DcMNPs were found as a convenient vehicle for targeted doxorubicin delivery in cancer therapy. Poly (I:C) binding on doxorubicin loaded DcMNPs (DcMNPs-Dox) was reported for the first time in the literature. It was also demonstrated that loading of doxorubicin into the cavities of DcMNPs increases the binding efficiency of poly (I:C) to the surface functional groups of dendrimer up to 10 times. When we compare the in vitro cytotoxic properties of doxorubicin, poly (I:C) and poly (I:C) bound doxorubicin loaded DcMNPs (PIC-DcMNPs-Dox), it was observed that PIC-DcMNPs-Dox show the highest cytotoxic effect by passing the cell resistance mechanisms on doxorubicin resistant MCF7 (MCF7/Dox) cells. Results demonstrated that applying PIC-DcMNPs-Dox would improve the efficacy by increasing the biocompatibility of system in blood stream and the toxicity inside tumor cells. These results provide invaluable information and new insight for the design and optimization of a novel combinational drug delivery system for targeted cancer therapy.

Notch-1 mediated cardiac protection following embryonic and induced pluripotent stem cell transplantation in doxorubicin-induced heart failure

Doxorubicin (DOX), an effective chemotherapeutic drug used in the treatment of various cancers, is limited in its clinical applications due to cardiotoxicity. Recent studies suggest that transplanted adult stem cells inhibit DOX-induced cardiotoxicity. However, the effects of transplanted embryonic stem (ES) and induced pluripotent stem (iPS) cells are completely unknown in DOX-induced left ventricular dysfunction following myocardial infarction (MI). In brief, C57BL/6 mice were divided into five groups: Sham, DOX-MI, DOX-MI+cell culture (CC) media, DOX-MI+ES cells, and DOX-MI+iPS cells. Mice were injected with cumulative dose of 12 mg/kg of DOX and 2 weeks later, MI was induced by coronary artery ligation. Following ligation, 5×10⁴ ES or iPS cells were delivered into the peri-infarct region. At day 14 post-MI, echocardiography was performed, mice were sacrificed, and hearts were harvested for further analyses. Our data reveal apoptosis was significantly inhibited in ES and iPS cell transplanted hearts compared with respective controls (DOX-MI+ES: 0.48±0.06% and DOX-MI+iPS: 0.33±0.05% vs. DOX-MI: 1.04±0.07% and DOX-MI+CC: 0.96±0.21%; p<0.05). Furthermore, a significant increase in levels of Notch-1 (p<0.05), Hes1 (p<0.05), and pAkt (p<0.05) were observed whereas a decrease in the levels of PTEN (p<0.05), a negative regulator of Akt, was evident following stem cell transplantation. Moreover, hearts transplanted with stem cells demonstrated decreased vascular and interstitial fibrosis (p<0.05) as well as MMP-9 expression (p<0.01) compared with controls. Additionally, heart function was significantly improved (p<0.05) in both cell-transplanted groups. In conclusion, our data show that transplantation of ES and iPS cells blunt DOX-induced adverse cardiac remodeling, which is associated with improved cardiac function, and these effects are mediated by the Notch pathway.

Doxorubicin combined with celecoxib inhibits tumor growth of medullary thyroid carcinoma in xenografted mice

The aim of the present study was to investigate the antitumor effect of celecoxib (CXB) combined with doxorubicin (DOX) on the subcutaneous xenograft tumor of medullary thyroid carcinoma in nude mice, and to analyze the possible mechanism of action. Nude mice with xenografted medullary thyroid carcinoma (MTC) were randomly divided into the control, CXB, DOX and DOX plus CXB groups, and the drug treatment was administered for three weeks. It was found that the tumor inhibition rates and the apoptosis index in the treatment groups were higher than in the control group (P<0.01), and that these values were higher in the combination group compared with the single-drug group (P<0.01). DOX alone upregulated the cyclooxygenase-2 and multidrug-resistance 1 expression levels, and the combination of CXB and DOX or CXB alone notably decreased the expression level of the two proteins compared with no treatment. The results of the present study provide evidence that a combination of DOX and CXB is a potential drug candidate for the treatment of MTC.

Antimutagenic compounds and their possible mechanisms of action

Mutagenicity refers to the induction of permanent changes in the DNA sequence of an organism, which may result in a heritable change in the characteristics of living systems. Antimutagenic agents are able to counteract the effects of mutagens. This group of agents includes both natural and synthetic compounds. Based on their mechanism of action among antimutagens, several classes of compounds may be distinguished. These are compounds with antioxidant activity; compounds that inhibit the activation of mutagens; blocking agents; as well as compounds characterized with several modes of action. It was reported previously that several antitumor compounds act through the antimutagenic mechanism. Hence, searching for antimutagenic compounds represents a rapidly expanding field of cancer research. It may be observed that, in recent years, many publications were focused on the screening of both natural and synthetic compounds for their beneficial muta/antimutagenicity profile. Thus, the present review attempts to give a brief outline on substances presenting antimutagenic potency and their possible mechanism of action. Additionally, in the present paper, a screening strategy for mutagenicity testing was presented and the characteristics of the most widely used antimutagenicity assays were described.

Phosphodiesterase 5 inhibitors enhance chemotherapy killing in gastrointestinal/genitourinary cancer cells

The present studies determined whether clinically relevant phosphodiesterase 5 (PDE5) inhibitors interacted with clinically relevant chemotherapies to kill gastrointestinal/genitourinary cancer cells. In bladder cancer cells, regardless of H-RAS mutational status, at clinically achievable doses, PDE5 inhibitors interacted in a greater than additive fashion with doxorubicin/mitomycin C/gemcitabine/cisplatin/paclitaxel to cause cell death. In pancreatic tumor cells expressing mutant active K-RAS, PDE5 inhibitors interacted in a greater than additive fashion with doxorubicin/gemcitabine/paclitaxel to cause cell death. The most potent PDE5 inhibitor was sildenafil. Knock down of PDE5 expression recapitulated the combination effects of PDE5 inhibitor drugs with chemotherapy drugs. Expression of cellular FLICE-like inhibitory protein-short did not significantly inhibit chemotherapy lethality but did significantly reduce enhanced killing in combination with sildenafil. Overexpression of B-cell lymphoma-extra large suppressed individual and combination drug toxicities. Knock down of CD95 or Fas-associated death domain protein suppressed drug combination toxicity. Combination toxicity was also abolished by necrostatin or receptor interacting protein 1 knock down. Treatment with PDE5 inhibitors and chemotherapy drugs promoted autophagy, which was maximal at ∼24 hour posttreatment, and 3-methyl adenine or knock down of Beclin1 suppressed drug combination lethality by ∼50%. PDE5 inhibitors enhanced and prolonged the induction of DNA damage as judged by Comet assays and γhistone 2AX (γH2AX) and checkpoint kinase 2 (CHK2) phosphorylation. Knock down of ataxia telangiectasia mutated suppressed γH2AX and CHK2 phosphorylation and enhanced drug combination lethality. Collectively our data demonstrate that the combination of PDE5 inhibitors with standard of care chemotherapy agents for gastrointestinal/genitourinary cancers represents a novel modality.

d-limonene suppresses doxorubicin-induced oxidative stress and inflammation via repression of COX-2, iNOS, and NFκB in kidneys of Wistar rats

d-limonene is a naturally occurring monoterpene and has been found to posses numerous therapeutic properties. In this study, we used d-limonene as a protective agent against the nephrotoxic effects of anticancer drug doxorubicin (Dox). Rats were given d-limonene at doses of 5% and 10% mixed with diet for 20 consecutive days. Dox was give at the dose of 20 mg/kg body weight intraperitoneally. The protective effects of d-limonene on Dox-induced oxidative stress and inflammation were investigated by assaying oxidative stress biomarkers, lipid peroxidation, serum toxicity markers, proinflammatory cytokines, and expression of nuclear factor kappa B (NFκB), cyclo-oxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) and Nitrite levels. Administration of Dox (20 mg/kg body weight) in rats enhanced renal lipid peroxidation; depleted glutathione content and anti-oxidant enzymes; elevated levels of kidney toxicity markers viz. kidney injury molecule-1 (KIM-1), blood urea nitrogen (BUN), and creatinine; enhanced expression of NFκB, COX-2, and iNOS and nitric oxide. Treatment with d-limonene prevented oxidative stress by restoring the levels of antioxidant enzymes, further both doses of 5% and 10% showed significant decrease in inflammatory response. Both the doses of d-limonene significantly decreased the levels of kidney toxicity markers KIM-1, BUN, and creatinine. d-limonene also effectively decreased the Dox induced overexpression of NF-κB, COX-2, and iNOS and nitric oxide. Data from the present study indicate the protective role of d-limonene against Dox-induced renal damage.

AMP-activated protein kinase α2 and E2F1 transcription factor mediate doxorubicin-induced cytotoxicity by forming a positive signal loop in mouse embryonic fibroblasts and non-carcinoma cells

Doxorubicin is one of the most widely used anti-cancer drugs, but its clinical application is compromised by severe adverse effects in different organs including cardiotoxicity. In the present study we explored mechanisms of doxorubicin-induced cytotoxicity by revealing a novel role for the AMP-activated protein kinase α2 (AMPKα2) in mouse embryonic fibroblasts (MEFs). Doxorubicin robustly induced the expression of AMPKα2 in MEFs but slightly reduced AMPKα1 expression. Our data support the previous notion that AMPKα1 harbors survival properties under doxorubicin treatment. In contrast, analyses of Ampkα2(-/-) MEFs, gene knockdown of AMPKα2 by shRNA, and inhibition of AMPKα2 activity with an AMPK inhibitor indicated that AMPKα2 functions as a pro-apoptotic molecule under doxorubicin treatment. Doxorubicin induced AMPKα2 at the transcription level via E2F1, a transcription factor that regulates apoptosis in response to DNA damage. E2F1 directly transactivated the Ampkα2 gene promoter. In turn, AMPKα2 significantly contributed to stabilization and activation of E2F1 by doxorubicin, forming a positive signal amplification loop. AMPKα2 directly interacted with and phosphorylated E2F1. This signal loop was also detected in H9c2, C2C12, and ECV (human epithelial cells) cells as well as mouse liver under doxorubicin treatment. Resveratrol, which has been suggested to attenuate doxorubicin-induced cytotoxicity, significantly blocked induction of AMPKα2 and E2F1 by doxorubicin, leading to protection of these cells. This signal loop appears to be non-carcinoma-specific because AMPKα2 was not induced by doxorubicin in five different tested cancer cell lines. These results suggest that AMPKα2 may serve as a novel target for alleviating the cytotoxicity of doxorubicin.

Multimodal luminescent-magnetic boron nitride nanotubes@NaGdF4:Eu structures for cancer therapy

Boron nitride nanotubes@NaGdF4:Eu composites with core@shell structures were fabricated to trace and manipulate BNNTsin vitro.

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

Background/aim:

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

Method:

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

Results:

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

Conclusion:

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

Attenuation of doxorubicin-induced cardiotoxicity by mdivi-1: a mitochondrial division/mitophagy inhibitor

Doxorubicin is one of the most effective anti-cancer agents. However, its use is associated with adverse cardiac effects, including cardiomyopathy and progressive heart failure. Given the multiple beneficial effects of the mitochondrial division inhibitor (mdivi-1) in a variety of pathological conditions including heart failure and ischaemia and reperfusion injury, we investigated the effects of mdivi-1 on doxorubicin-induced cardiac dysfunction in naïve and stressed conditions using Langendorff perfused heart models and a model of oxidative stress was used to assess the effects of drug treatments on the mitochondrial depolarisation and hypercontracture of cardiac myocytes. Western blot analysis was used to measure the levels of p-Akt and p-Erk 1/2 and flow cytometry analysis was used to measure the levels p-Drp1 and p-p53 upon drug treatment. The HL60 leukaemia cell line was used to evaluate the effects of pharmacological inhibition of mitochondrial division on the cytotoxicity of doxorubicin in a cancer cell line. Doxorubicin caused a significant impairment of cardiac function and increased the infarct size to risk ratio in both naïve conditions and during ischaemia/reperfusion injury. Interestingly, co-treatment of doxorubicin with mdivi-1 attenuated these detrimental effects of doxorubicin. Doxorubicin also caused a reduction in the time taken to depolarisation and hypercontracture of cardiac myocytes, which were reversed with mdivi-1. Finally, doxorubicin caused a significant elevation in the levels of signalling proteins p-Akt, p-Erk 1/2, p-Drp1 and p-p53. Co-incubation of mdivi-1 with doxorubicin did not reduce the cytotoxicity of doxorubicin against HL-60 cells. These data suggest that the inhibition of mitochondrial fission protects the heart against doxorubicin-induced cardiac injury and identify mitochondrial fission as a new therapeutic target in ameliorating doxorubicin-induced cardiotoxicity without affecting its anti-cancer properties.

Cardiac expression of human type 2 iodothyronine deiodinase increases glucose metabolism and protects against doxorubicin-induced cardiac dysfunction in male mice

Altered glucose metabolism in the heart is an important characteristic of cardiovascular and metabolic disease. Because thyroid hormones have major effects on peripheral metabolism, we examined the metabolic effects of heart-selective increase in T3 using transgenic mice expressing human type 2 iodothyronine deiodinase (D2) under the control of the α-myosin heavy chain promoter (MHC-D2). Hyperinsulinemic-euglycemic clamps showed normal whole-body glucose disposal but increased hepatic insulin action in MHC-D2 mice as compared to wild-type (WT) littermates. Insulin-stimulated glucose uptake in heart was not altered, but basal myocardial glucose metabolism was increased by more than two-fold in MHC-D2 mice. Myocardial lipid levels were also elevated in MHC-D2 mice, suggesting an overall up-regulation of cardiac metabolism in these mice. The effects of doxorubicin (DOX) treatment on cardiac function and structure were examined using M-mode echocardiography. DOX treatment caused a significant reduction in ventricular fractional shortening and resulted in more than 50% death in WT mice. In contrast, MHC-D2 mice showed increased survival rate after DOX treatment, and this was associated with a six-fold increase in myocardial glucose metabolism and improved cardiac function. Myocardial activity and expression of AMPK, GLUT1, and Akt were also elevated in MHC-D2 and WT mice following DOX treatment. Thus, our findings indicate an important role of thyroid hormone in cardiac metabolism and further suggest a protective role of glucose utilization in DOX-mediated cardiac dysfunction.