Cannabidiol Protects against Doxorubicin-Induced Cardiomyopathy by Modulating Mitochondrial Function and Biogenesis

Doxorubicin (DOX) is a widely used, potent chemotherapeutic agent; however, its clinical application is limited because of its dose-dependent cardiotoxicity. DOX’s cardiotoxicity involves increased oxidative/nitrative stress, impaired mitochondrial function in cardiomyocytes/endothelial cells and cell death. Cannabidiol (CBD) is a nonpsychotropic constituent of marijuana, which is well tolerated in humans, with antioxidant, antiinflammatory and recently discovered antitumor properties. We aimed to explore the effects of CBD in a well-established mouse model of DOX-induced cardiomyopathy. DOX-induced cardiomyopathy was characterized by increased myocardial injury (elevated serum creatine kinase and lactate dehydrogenase levels), myocardial oxidative and nitrative stress (decreased total glutathione content and glutathione peroxidase 1 activity, increased lipid peroxidation, 3-nitrotyrosine formation and expression of inducible nitric oxide synthase mRNA), myocardial cell death (apoptotic and poly[ADP]-ribose polymerase 1 [PARP]-dependent) and cardiac dysfunction (decline in ejection fraction and left ventricular fractional shortening). DOX also impaired myocardial mitochondrial biogenesis (decreased mitochondrial copy number, mRNA expression of peroxisome proliferator-activated receptor γ coactivator 1-alpha, peroxisome proliferator-activated receptor alpha, estrogen-related receptor alpha), reduced mitochondrial function (attenuated complex I and II activities) and decreased myocardial expression of uncoupling protein 2 and 3 and medium-chain acyl-CoA dehydrogenase mRNA. Treatment with CBD markedly improved DOX-induced cardiac dysfunction, oxidative/nitrative stress and cell death. CBD also enhanced the DOX-induced impaired cardiac mitochondrial function and biogenesis. These data suggest that CBD may represent a novel cardioprotective strategy against DOX-induced cardiotoxicity, and the above-described effects on mitochondrial function and biogenesis may contribute to its beneficial properties described in numerous other models of tissue injury.     

Sirtuin-3 (SIRT3) Protein Attenuates Doxorubicin-induced Oxidative Stress and Improves Mitochondrial Respiration in H9c2 Cardiomyocytes

Doxorubicin (DOX) is a chemotherapeutic agent effective in the treatment of many cancers. However, cardiac dysfunction caused by DOX limits its clinical use. DOX is believed to be harmful to cardiomyocytes by interfering with the mitochondrial phospholipid cardiolipin and causing inefficient electron transfer resulting in the production of reactive oxygen species (ROS). Sirtuin-3 (SIRT3) is a class III lysine deacetylase that is localized to the mitochondria and regulates mitochondrial respiration and oxidative stress resistance enzymes such as superoxide dismutase-2 (SOD2). The purpose of this study was to determine whether SIRT3 prevents DOX-induced mitochondrial ROS production. Administration of DOX to mice suppressed cardiac SIRT3 expression, and DOX induced a dose-dependent decrease in SIRT3 and SOD2 expression in H9c2 cardiomyocytes. SIRT3-null mouse embryonic fibroblasts produced significantly more ROS in the presence of DOX compared with wild-type cells. Overexpression of wild-type SIRT3 increased cardiolipin levels and rescued mitochondrial respiration and SOD2 expression in DOX-treated H9c2 cardiomyocytes and attenuated the amount of ROS produced following DOX treatment. These effects were absent when a deacetylase-deficient SIRT3 was expressed in H9c2 cells. Our results suggest that overexpression of SIRT3 attenuates DOX-induced ROS production, and this may involve increased SOD2 expression and improved mitochondrial bioenergetics. SIRT3 activation could be a potential therapy for DOX-induced cardiac dysfunction.     

Attenuation of doxorubicin-induced contractile and mitochondrial dysfunction in mouse heart by cellular glutathione peroxidase

The cardiac toxicity of doxorubicin (DOX), a potent anticancer anthracycline antibiotic, is believed to be mediated through the generation of reactive oxygen species (ROS) in cardiomyocytes. This study aims to determine the function of cellular glutathione peroxidase (Gpx1), which is located in both mitochondria and cytosol, in defense against DOX-induced cardiomyopathy using a line of transgenic mice with cardiac overexpression of Gpx1. The Gpx1-overexpressing hearts were markedly more resistant than nontransgenic hearts to DOX-induced acute functional derangements, including impaired contractility and diastolic properties, decreased coronary flow rate, and reduced heart rate. In addition, DOX treatment impairs mitochondrial function of nontransgenic hearts as evident in a decreased rate of NAD-linked State 3 respiration, presumably a result of inactivation of complex I activity. This is associated with increases in the rates of NAD- and FAD-linked State 4 respiration and declines in P/O ratio, suggesting that the electron transfer and oxidative phosphorylation are uncoupled in these mitochondrial samples. These functional deficits of mitochondria could be largely prevented by Gpx1 overexpression. Taken together, these studies provide new evidence to further support the role of ROS, particularly H(2)O(2) and/or fatty acid hydroperoxides, in causing contractile and mitochondrial dysfunction in mouse hearts acutely exposed to DOX.     

Resveratrol prevents doxorubicin cardiotoxicity through mitochondrial stabilization and the Sirt1 pathway

Doxorubicin (DOX) is one of the most effective chemotherapeutic drugs; however, its incidence of cardiotoxicity compromises its therapeutic index. DOX-induced heart failure is thought to be caused by reduction/oxidation cycling of DOX to generate oxidative stress and cardiomyocyte cell death. Resveratrol (RV), a stilbene found in red wine, has been reported to play a cardioprotective role in diseases associated with oxidative stress. The objective of this study was to test the ability of RV to protect against DOX-induced cardiomyocyte death. We hypothesized that RV protects cardiomyocytes from DOX-induced oxidative stress and subsequent cell death through changes in mitochondrial function. DOX induced a rapid increase in reactive oxygen species (ROS) production in cardiac cell mitochondria, which was inhibited by pretreatment with RV, most likely owing to an increase in MnSOD activity. This effect of RV caused additional polarization of the mitochondria in the absence and presence of DOX to increase mitochondrial function. RV pretreatment also prevented DOX-induced cardiomyocyte death. The protective ability of RV against DOX was abolished when Sirt1 was inhibited by nicotinamide. Our data suggest that RV protects against DOX-induced oxidative stress through changes in mitochondrial function, specifically the Sirt1 pathway leading to cardiac cell survival.     

Doxorubicin-induced thiol-dependent alteration of cardiac mitochondrial permeability transition and respiration

Doxorubicin (DOX) is a highly effective treatment for several forms of cancer. However, clinical experience shows that DOX induces a cumulative and dose-dependent cardiomyopathy that has been ascribed to redox-cycling of the drug on the mitochondrial respiratory chain generating free radicals and oxidative stress in the process. Mitochondrial dysfunction including induction of the mitochondrial permeability transition (MPT) and inhibition of mitochondrial respiration have been implicated as major determinants in the pathogenesis of DOX cardiotoxicity. The present work was aimed at investigating whether the inhibition of mitochondrial respiration occurs secondarily to MPT induction in heart mitochondria isolated from DOX-treated rats and whether one or both consequences of DOX treatment are related with oxidation of protein thiol residues. DOX-induced oxidative stress was associated with the accumulation of products of lipid peroxidation and the depletion of alpha-tocopherol in cardiac mitochondrial membranes. No changes in mitochondrial coenzyme Q9 and Q10 concentrations were detected in hearts of DOX-treated rats. Cardiac mitochondria from DOX-treated rats were more susceptible to diamide-dependent induction of the MPT. Although DOX treatment did not affect state 4 respiration, state 3 respiration was decreased in heart mitochondria isolated from DOX-treated rats, which was reversed in part by adding either cyclosporin A or dithiothreitol, but not Trolox. The results suggest that in DOX-treated rats, (i) induction of the MPT is at least in part responsible for decreased mitochondrial respiration, (ii) heart mitochondria are more susceptible to diamide induced-MPT, (iii) thiol-dependent alteration of mitochondrial respiration is partially reversible ex vivo with dithiothreitol. Collectively, these data are consistent with the thesis that thiol-dependent alteration of MPT and respiration is an important factor in DOX-induced mitochondrial dysfunction.     

Doxorubicin-induced cardiomyocyte apoptosis: Role of mitofusin 2

BackgroundDoxorubicin (DOX) is an anti-tumor agent that is widely used in clinical setting for cancer treatment. The application of the DOX, however, is limited by its cardiac toxicity which can induce heart failure through an undefined mechanism. Mitofusin 2 (Mfn2) is a mitochondrial GTPase fusion protein that is located on the outer membrane of mitochondria (OMM). The Mfn2 plays an important role in mitochondrial fusion and fission. The aim of this study is to identify the role of the Mfn2 in DOX-induced cardiomyocyte apoptosis.MethodsCultured neonatal rat cardiomyocytes were used in this study. Mfn2 expression in cardiomyocytes was determined after the cardiomyocytes were challenged with DOX. Cardiomyocyte mitochondrial fission, mitochondrial reactive oxygen species (ROS) production was assessed with mitochondrial fragmentation and MitoSOX fluorescence probe, respectively. Cardiomyocyte apoptosis was determined with caspase3 activity and TUNEL staining.ResultsChallenging of the cardiomyocytes with DOX resulted in increasing in cardiomyocyte oxidative stress and apoptosis. In addition, levels of Mfn2 in cardiomyocytes were decreased after the cells were challenged with DOX which was associated with increased mitochondrial fission (fragmentation) and mitochondrial ROS production. An increase in cardiomyocyte levels of Mfn2 attenuated the DOX-induced increase in mitochondrial fission and prevented cardiomyocyte mitochondrial ROS production. An increase in cardiomyocyte levels of Mfn2 or pretreatment of cardiomyocytes with an anti-oxidant, Mito-tempo, also prevented the DOX-induced cardiomyocyte apoptosis.ConclusionOur results indicate that DOX results in a decreased cardiomyocyte Mfn2 expression which promotes mitochondrial fission and ROS production further leads to cardiomyocyte apoptosis.     

Glutathione peroxidase 1-deficient mice are more susceptible to doxorubicin-induced cardiotoxicity

Doxorubicin (DOX)-induced cardiotoxicity is thought to be mediated by the generation of superoxide anion radicals (superoxide) from redox cycling of DOX in cardiomyocyte mitochondria. Reduction of superoxide generates H(2)O(2), which diffuses throughout the cell and potentially contributes to oxidant-mediated cardiac injury. The mitochondrial and cytosolic glutathione peroxidase 1 (Gpx1) primarily functions to eradicate H(2)O(2). In this study, we hypothesize that Gpx1 plays a pivotal role in the clearance of H(2)O(2) generated by DOX. To test this hypothesis, we compared DOX-induced cardiac dysfunction, mitochondrial injury, protein nitration, and apoptosis in Gpx1-deficient and wild type mouse hearts. The Gpx1-deficient hearts showed increased susceptibility to DOX-induced acute functional derangements than wild type hearts, including impaired contractility and diastolic properties, decreased coronary flow rate, and reduced heart rate. In addition, DOX treatment impaired the mitochondrial function of Gpx1-deficient hearts. Specifically, Gpx1-deficient hearts treated with DOX demonstrated an increased rate of NAD-linked state 4 respiration and a decline in the P/O ratio relative to wild type hearts, suggesting that DOX uncouples the electron transfer chain and oxidative phosphorylation in Gpx1-deficient hearts. Finally, apoptosis and protein nitration were significantly increased in Gpx1-deficient mouse hearts compared to wild type hearts. These studies suggest that Gpx1 plays significant roles in protecting DOX-induced mitochondrial impairment and cardiac dysfunction in the acute phase.     

Ferritin heavy chain as main mediator of preventive effect of metformin against mitochondrial damage induced by doxorubicin in cardiomyocytes

The efficacy of doxorubicin (DOX) as an antitumor agent is greatly limited by the induction of cardiomyopathy, which results from mitochondrial dysfunction and iron-catalyzed oxidative stress in the cardiomyocyte. Metformin (MET) has been seen to have a protective effect against the oxidative stress induced by DOX in cardiomyocytes through its modulation of ferritin heavy chain (FHC), the main iron-storage protein. This study aimed to assess the involvement of FHC as a pivotal molecule in the mitochondrial protection offered by MET against DOX cardiotoxicity. The addition of DOX to adult mouse cardiomyocytes (HL-1 cell line) increased the cytosolic and mitochondrial free iron pools in a time-dependent manner. Simultaneously, DOX inhibited complex I activity and ATP generation and induced the loss of mitochondrial membrane potential. The mitochondrial dysfunction induced by DOX was associated with the release of cytochrome c to the cytosol, the activation of caspase 3, and DNA fragmentation. The loss of iron homeostasis, mitochondrial dysfunction, and apoptosis induced by DOX were prevented by treatment with MET 24 h before the addition of DOX. The involvement of FHC and NF-κB was determined through siRNA-mediated knockdown. Interestingly, the presilencing of FHC or NF-κB with specific siRNAs blocked the protective effect induced by MET against DOX cardiotoxicity. These findings were confirmed in isolated primary neonatal rat cardiomyocytes. In conclusion, these results deepen our knowledge of the protective action of MET against DOX-induced cardiotoxicity and suggest that therapeutic strategies based on FHC modulation could protect cardiomyocytes from the mitochondrial damage induced by DOX by restoring iron homeostasis.     

Resveratrol treatment protects against doxorubicin-induced cardiotoxicity by alleviating oxidative damage

The possible protective effects of resveratrol (RVT) against cardiotoxicity were investigated in Wistar albino rats treated with saline, saline+doxorubicin (DOX; 20 mg/kg) or RVT (10 mg/kg)+DOX. Blood pressure and heart rate were recorded on the 1^st week and on the 7^th week, while cardiomyopathy was assessed using transthoracic echocardiography before the rats were decapitated. DOX-induced cardiotoxicity resulted in decreased blood pressure and heart rate, but lactate dehydrogenase, creatine phosphokinase, total cholesterol, triglyceride, aspartate aminotransferase and 8-OHdG levels were increased in plasma. Moreover, DOX caused a significant decrease in plasma total antioxidant capacity along with a reduction in cardiac superoxide dismutase, catalase and Na⁺,K⁺-ATPase activities and glutathione contents, while malondialdehyde, myelopreoxidase activity and the generation of reactive oxygen species were increased in the cardiac tissue. On the other hand, RVT markedly ameliorated the severity of cardiac dysfunction, while all oxidant responses were prevented; implicating that RVT may be of therapeutic use in preventing oxidative stress due to DOX toxicity.     

Nitric oxide and oxidative stress in brain and heart of normal rats treated with doxorubicin: role of aminoguanidine

Doxorubicin (DOX) is a potent antitumor antibiotic drug known to cause severe cardiac toxicity. Moreover, its adverse effects were found to be extended to the cerebral tissue. Several mechanisms for this toxicity have been ascribed. Currently, one of the most accepted mechanisms is through free radicals; however, the exact role of nitric oxide (NO) is still unclear. Accordingly, a NO-synthase inhibitor with some antioxidant property, aminoguanidine (AG), was selected to examine its potential protective effect against DOX-induced toxicity. Male Wistar albino rats (150-200 g) were allocated into a normal control group, DOX-induced toxicity group, and DOX + AG-treated group. DOX was injected i.p. at a dose of 10 mg/kg divided into four equal injections over a period of 2 weeks. AG was injected i.p. at a dose of 100 mg/kg 1 h before each DOX injection. The animals were sacrificed 24 h after the last DOX injection and the following parameters were measured: serum lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) activities, cardiac and cerebral contents of malondialdehyde (MDA), conjugated diene (CD), glutathione (GSH), NO, and cytosolic calcium, as well as superoxide dismutase (SOD) and glutathione peroxidase (GSHP(X)) activities. Cardiotoxicity was manifested by a marked increase in serum LDH and CPK in addition to the sharp increase in MDA reaching eightfolds the basal level. This was accompanied by significant increase in CD, NO, cytosolic calcium, SOD, and GSHP(X) content/activity by 69, 85, 76, 125, and 41% respectively as compared to normal control. On the other hand, GSH was significantly depressed. In brain, only significant increase in MDA and GSHP(X) and decrease in GSH were obtained but to a lesser extent than the cardiac tissue. AG treatment failed to prevent the excessive release of cardiac enzymes; however, it alleviated the adverse effects of DOX in heart. AG administration resulted in marked decrease in the elevated levels of MDA, NO, SOD, and GSHP(X), however, MDA level was still pathological. The altered parameters in brain were restored by AG. It is concluded that, AG could not provide complete protection against DOX-induced toxicity. Therefore, it is recommended that, maintenance of the endogenous antioxidant, GSH, and regulation of calcium homeostasis must be considered, rather than NO formation, to guard against DOX-induced toxicity.     

Attenuation of doxorubicin-induced cardiotoxicity and genotoxicity by an indole-based natural compound 3,3′-diindolylmethane (DIM) through activation of Nrf2/ARE signaling pathways and inhibiting apoptosis

The most crucial complication related to doxorubicin (DOX) therapy is nonspecific cytotoxic effect on healthy normal cells. The clinical use of this broad-spectrum chemotherapeutic agent is restricted due to development of severe form of cardiotoxicity, myelosuppression, and genotoxicity which interfere with therapeutic schedule, compromise treatment outcome and may lead to secondary malignancy. 3,3′-diindolylmethane (DIM) is a naturally occurring plant alkaloid formed by the hydrolysis of indolylmethyl glucosinolate (glucobrassicin). Therefore, the present study was undertaken to investigate the protective role of DIM against DOX-induced toxicity in mice. DOX was administered (5?mg/kg b.w., i.p.) and DIM was administered (25?mg/kg b.w., p.o.) in concomitant and 15 days pretreatment schedule. Results showed that DIM significantly attenuated DOX-induced oxidative stress in the cardiac tissues by reducing the levels of free radicals and lipid peroxidation, and by enhancing the level of glutathione (reduced) and the activity of antioxidant enzymes. The chemoprotective potential of DIM was confirmed by histopathological evaluation of heart and bone marrow niche. Moreover, DIM considerably mitigated DOX-induced clastogenicity, DNA damage, apoptosis, and myeloid hyperplasia in bone marrow niche. In addition, oral administration of DIM significantly (p?相似文献   

Redox proteomic identification of HNE-bound mitochondrial proteins in cardiac tissues reveals a systemic effect on energy metabolism after doxorubicin treatment

Doxorubicin (DOX), one of the most effective anticancer drugs, is known to generate progressive cardiac damage, which is due, in part, to DOX-induced reactive oxygen species (ROS). The elevated ROS often induce oxidative protein modifications that result in alteration of protein functions. This study demonstrates that the level of proteins adducted by 4-hydroxy-2-nonenal (HNE), a lipid peroxidation product, is significantly increased in mouse heart mitochondria after DOX treatment. A redox proteomics method involving two-dimensional electrophoresis followed by mass spectrometry and investigation of protein databases identified several HNE-modified mitochondrial proteins, which were verified by HNE-specific immunoprecipitation in cardiac mitochondria from the DOX-treated mice. The majority of the identified proteins are related to mitochondrial energy metabolism. These include proteins in the citric acid cycle and electron transport chain. The enzymatic activities of the HNE-adducted proteins were significantly reduced in DOX-treated mice. Consistent with the decline in the function of the HNE-adducted proteins, the respiratory function of cardiac mitochondria as determined by oxygen consumption rate was also significantly reduced after DOX treatment. Treatment with Mn(III) meso-tetrakis(N-n-butoxyethylpyridinium-2-yl)porphyrin, an SOD mimic, averted the doxorubicin-induced mitochondrial dysfunctions as well as the HNE–protein adductions. Together, the results demonstrate that free radical-mediated alteration of energy metabolism is an important mechanism mediating DOX-induced cardiac injury, suggesting that metabolic intervention may represent a novel approach to preventing cardiac injury after chemotherapy.     

Cardiolipin nanodisks confer protection against doxorubicin-induced mitochondrial dysfunction

Doxorubicin (DOX) is an aqueous soluble anthracycline therapeutic widely used in cancer treatment. Although DOX anti-cancer activity is dose-dependent, increased dosage enhances the risk of cardiotoxicity. Despite intensive investigation, the molecular basis of this undesirable side effect has yet to be established. In addition to serving as a DNA intercalation agent, DOX is known to bind to the signature mitochondrial phospholipid, cardiolipin (CL). Consistent with this, DOX associates with aqueous soluble nanoparticles, termed nanodisks (ND), comprised solely of CL and an apolipoprotein scaffold. Fluorescence microscopy analysis revealed that DOX uptake, and targeting to the nucleus of cultured hepatocarcinoma (HepG2) or breast cancer (MCF7) cells, was unaffected by its association with CL-ND. Subsequent studies revealed that free DOX and DOX-CL-ND were equivalent in terms of growth inhibition activity in both cell lines. By contrast, in studies with H9C2 cardiomyocytes, DOX-CL-ND induced a lesser concentration-dependent decline in cell viability than free DOX. Whereas incubation of H9C2 cardiomyocytes with free DOX caused a steep decline in maximal oxygen consumption rate, DOX-CL-ND treated cells were largely unaffected. The data indicate that association of DOX with CL-ND does not diminish its cancer cell growth inhibition activity yet confers protection to cardiomyocytes from DOX-induced effects on aerobic respiration. This study illustrates that interaction with CL plays a role in DOX-induced mitochondrial dysfunction and suggests CL-ND provide a tool for investigating the mechanistic basis of DOX-induced cardiotoxicity.     

Attenuation of doxorubicin-induced hypothalamic-pituitary-testicular axis dysfunction by diphenyl diselenide involves suppression of hormonal deficits,oxido-inflammatory stress and caspase 3 activity in rats

BackgroundDoxorubicin (DOX) is one of the popular anti-cancer drugs in the world and several literatures have implicated it in various toxicities especially cardiotoxicity and reproductive toxicity. Diphenyl diselenide (DPDS) is well acknowledged for its compelling pharmacological effects in numerous disease models and chemically-mediated toxicity. This study was carried out to investigate the effect of DPDS on DOX-induced changes in the reproductive indices of male Wistar rats.MethodsRats were intraperitoneally injected with 7.5 mg/kg body weight of DOX alone once followed by treatment with DPDS at 5 and 10 mg/kg for seven successive days. Excised hypothalamus, testes and epididymis were processed for biochemical and histological analyses.ResultsDPDS treatment significantly (p < 0.05) abated DOX-induced oxidative damage by decreasing the levels of oxidative stress indices such as hydrogen peroxide, reactive oxygen and nitrogen species, and lipid peroxidation with a respective improvement in the level of glutathione in the hypothalamic, testicular and epididymal tissues of DOX-treated rats. The activities of antioxidant enzymes such as catalase, superoxide dismutase, glutathione S-transferase and glutathione peroxidase were upregulated in the DPDS co-treated group. DPDS co-treatment alleviates the burden of DOX-induced inflammation by significant reductions in myeloperoxidase activity, levels of nitric oxide and tumor necrosis factor alpha with concomitant decline in the activity of caspase-3, an apoptotic biomarker. Consequently, significant improvement in the spermiogram, levels of reproductive hormones (follicle stimulating hormone, luteinizing hormone, prolactin, serum testosterone and intra-testicular testosterone) levels in the DPDS co-treatment group in comparison to DOX alone-treated group were observed. Histology results of the testes and epididymis showed that DPDS significantly alleviated pathological lesions induced by DOX in the animals.ConclusionDPDS may modulate reproductive toxicity associated with DOX therapy in male cancer patients.     

Protective role of atorvastatin against doxorubicin-induced cardiotoxicity and testicular toxicity in mice

Doxorubicin (DOX), a potent chemotherapeutic agent, is widely used for the treatment of various malignancies. However, its clinical uses are limited due to its dose-dependent adverse effects particularly cardiac and testicular toxicities. DOX-induced toxicity is mainly due to the induction of oxidative stress. Atorvastatin (ATV), a 3-hydroxy 3-methyl glutaryl coenzyme A reductase inhibitor, with lipid-lowering activity, acts as an antioxidant at lower doses. It possesses pleiotropic effects independent of cholesterol-lowering property usually shown at lower doses, which include antioxidant and anti-inflammatory activities. The present study was aimed to investigate the possible protection exerted by atorvastatin against oxidative stress and DNA damage induced by DOX in the heart and testes of mice. The protective role of ATV in the heart and testes of DOX-treated mice was evident from the amelioration of oxidative stress, DNA and cellular damage. The present study clearly indicates that ATV offers a significant protection against DOX-induced oxidative stress and DNA damage in the heart and testes of mice.     

The beneficial role of exercise in mitigating doxorubicin-induced Mitochondrionopathy

Doxorubicin (DOX) is a widely used antineoplastic agent for a wide range of cancers, including hematological malignancies, soft tissue sarcomas and solid tumors. However, DOX exhibits a dose-related toxicity that results in life-threatening cardiomyopathy. In addition to the heart, there is evidence that DOX toxicity extends to other organs. This general toxicity seems to be related to mitochondrial network structural, molecular and functional impairments. Several countermeasures for these negative effects have been proposed, being physical exercise, not only one of the most effective non-pharmacologic strategy but also widely recommended as booster against cancer-related fatigue.It is widely accepted that mitochondria are critical sensors of tissue functionality, both modulated by DOX and exercise. Therefore, this review focuses on the current understanding of the mitochondrial-mediated mechanisms underlying the protective effect of exercise against DOX-induced toxicity, not only limited to the cardiac tissue, but also in other tissues such as skeletal muscle, liver and brain. We here analyze recent developments regarding the beneficial effects of exercise targeting mitochondrial responsive phenotypes against redox changes, mitochondrial bioenergetics, apoptotic, dynamics and quality control signalling affected by DOX treatment.     

Mitochondrionopathy phenotype in doxorubicin-treated Wistar rats depends on treatment protocol and is cardiac-specific

Although doxorubicin (DOX) is a very effective antineoplastic agent, its clinical use is limited by a dose-dependent, persistent and cumulative cardiotoxicity, whose mechanism remains to be elucidated. Previous works in animal models have failed to use a multi-organ approach to demonstrate that DOX-associated toxicity is selective to the cardiac tissue. In this context, the present work aims to investigate in vivo DOX cardiac, hepatic and renal toxicity in the same animal model, with special relevance on alterations of mitochondrial bioenergetics. To this end, male Wistar rats were sub-chronically (7 wks, 2 mg/Kg) or acutely (20 mg/Kg) treated with DOX and sacrificed one week or 24 hours after the last injection, respectively. Alterations of mitochondrial bioenergetics showed treatment-dependent differences between tissues. No alterations were observed for cardiac mitochondria in the acute model but decreased ADP-stimulated respiration was detected in the sub-chronic treatment. In the acute treatment model, ADP-stimulated respiration was increased in liver and decreased in kidney mitochondria. Aconitase activity, a marker of oxidative stress, was decreased in renal mitochondria in the acute and in heart in the sub-chronic model. Interestingly, alterations of cardiac mitochondrial bioenergetics co-existed with an absence of echocardiograph, histopathological or ultra-structural alterations. Besides, no plasma markers of cardiac injury were found in any of the time points studied. The results confirm that alterations of mitochondrial function, which are more evident in the heart, are an early marker of DOX-induced toxicity, existing even in the absence of cardiac functional alterations.