Doxorubicin-based chemotherapy is limited by the development of dose-dependent left ventricular dysfunction and congestive heart failure caused by reactive oxygen species (ROS). Uncoupling proteins (UCP) can inhibit mitochondrial ROS production as well as decrease myocyte damage from exogenous ROS. Prior studies have shown that cardiac UCP2 and UCP3 mRNA expression is decreased with acute doxorubicin treatment. However, the expression of UCP protein in hearts with doxorubicin cardiotoxicity and the resultant changes in mitochondrial function and oxidant stress have not been determined.
Heart failure was induced in Sprague-Dawley rats with intraperitoneal injections of doxorubicin (2 mg/kg t.i.w., total dose: 18 mg/kg). Mitochondria were isolated from mice receiving doxorubicin or saline injections for determination of UCP2 and UCP3 expression. In addition, mitochondrial respiration, ATP synthesis and ROS production were determined.
Doxorubicin-induced heart failure was associated with significant decreases in UCP2 and UCP3 protein expression compared to nonfailing hearts (p<0.05). While the rates of state 3 and state 4 respiration and ATP synthesis were lower in mitochondria isolated from failing hearts, the respiratory control ratio was 15% higher (p<0.05) and the ratio of ATP production to oxygen consumption was 25% higher (p<0.05) in mitochondria from failing hearts, indicating greater coupling between citric acid cycle flux and mitochondrial ATP synthesis. However, the decrease in UCP expression was associated with 50% greater mitochondrial ROS generation (p<0.05).
Downregulation of myocardial UCP2 and UCP3 in the setting of doxorubicin-induced heart failure is associated with improved efficiency of ATP synthesis, which might compensate for abnormal energy metabolism. However, this beneficial effect is counterbalanced by greater oxidant stress.
cardiotoxicity; mitochondria; reactive oxygen species; energetics
Doxorubicin is a widely used chemotherapy drug, but its application is associated with cardiotoxicity. Free radical generation and mitochondrial dysfunction are thought to contribute to doxorubicin-induced cardiac failure. Angiotensin-converting enzyme (ACE) inhibitors are commonly used as cardioprotective agents and have recently been shown in clinical studies to be efficacious in the prevention of anthracycline induced heart failure. Here we evaluated a mechanism for these protective effects by testing the ability of the ACE inhibitor enalapril to preserve mitochondrial function in a model of chronic doxorubicin treatment in rats.
Sprague Dawley rats were divided into three groups and followed for a total of 10 weeks: a) control-untreated, b) Doxorubicin treated (Dox), and c) Doxorubicin + Enalapril treated (DE). Doxorubicin was administered via intraperitoneal injection at weekly intervals from week 2 through week 7. Enalapril was administered in the drinking water of the DE group for the study duration.
Doxorubicin treatment produced a significant loss in left ventricular contractility (P< 0.05), decrease in mitochondrial function via impairment of state-3 respiration, decrease in the cytosolic fraction of ATP, and up-regulation of free radical production. Enalapril significantly attenuated the decrease in percent fractional shortening (P< 0.05) and prevented the doxorubicin-associated reduction in respiratory efficiency and cytosolic ATP content (P< 0.05). Importantly, enalapril also abolished the robust doxorubicin-induced increase in free radical formation.
Administration of enalapril attenuates doxorubicin-induced cardiac dysfunction via preservation of mitochondrial respiratory efficiency and reduction in doxorubicin-associated free radical generation.
doxorubicin; mitochondria; cardiotoxicity; ACE inhibitor; free radicals
Oxidative stress and disorders in calcium balance play a crucial role in the doxorubicin-induced cardiotoxicity. Moreover, many cardiotoxic targets of doxorubicin are regulated by iodothyronine hormones. The aim of the study was to evaluate effects of tetraiodothyronine (0.2, 2 mg/L) on oxidative stress in the cardiac muscle as well as contractility and cardiomyocyte damage markers in rats receiving doxorubicin (1.5 mg/kg) once a week for ten weeks. Doxorubicin was administered alone (DOX) or together with a lower (0.2T4 + DOX) and higher dose of tetraiodothyronine (2T4 + DOX). Two groups received only tetraiodothyronine (0.2T4, 2T4). Coadministration of tetraiodothyronine and doxorubicin increased the level of lipid peroxidation products and reduced RyR2 level when compared to untreated control and group exposed exclusively to doxorubicin. Insignificant differences in SERCA2 and occasional histological changes were observed. In conclusion, an increase of tetraiodothyronine level may be an additional risk factor of redox imbalance and RyR2 reduction in anthracycline cardiotoxicity.
Doxorubicin is an antibiotic broadly used in treatment of different types of solid tumors. The present study investigates whether L-carnitine, antioxidant agent, can reduce the hepatic damage induced by doxorubicin. Male Wistar albino rats were divided into six groups: group 1 was intraperitoneal injected with normal saline for 10 consecutive days; group 2, 3 and 4 were injected every other day with doxorubicin (3 mg/kg, i.p.), to obtain treatments with cumulative doses of 6, 12 and 18 mg/kg. The fifth group was injected with L-carnitine (200 mg/kg, i.p.) for 10 consecutive days and the sixth group was received doxorubicin (18 mg/kg) and L-carnitine (200 mg/kg). High cumulative dose of doxorubicin (18 mg/kg) significantly increases the biochemical levels of alanine transaminase, alkaline phosphatase, total bilirubin, thiobarbituric acid reactive substances (TBARs), total nitrate/nitrite (NOx) p < 0.05 and decrease in glutathione (GSH ), superoxide dismutase (SOD), glutathione peroxidase (GSHP x), glutathione-s-transferase (GST), glutathione reductase (GR) and catalase (CAT) activity p < 0.05. The effect of doxorubicin on the activity of antioxidant genes was confirmed by real time PCR in which the expression levels of these genes in liver tissue were significantly decrease compared to control p < 0.05. Interestingly, L-carnitine supplementation completely reversed the biochemical and gene expression levels induced by doxorubicin to the control values. In conclusion, data from this study suggest that the reduction of antioxidant defense during doxorubicin administration resulted in hepatic injury could be prevented by L-carnitine supplementation by decreasing the oxidative stress and preserving both the activity and gene expression level of antioxidant enzymes.
Interaction of doxorubicin DOX with iron and the consequent generation of reactive oxygen species (ROS) is a major player in DOX-induced cardiomyopathy. Accordingly, this study has been initiated to investigate the preventive effect of the iron chelator, desferrioxamine (DFX), against DOX-induced acute cardiotoxicity in rats. Male Wistar albino rats were divided into four groups and were injected intraperitoneally (I.P.) with normal saline, a single dose of DOX (15 mg/kg), a single dose of DFX (250 mg/kg) and a combined treatment with DFX (250 mg/kg) 30 min prior to a single dose of DOX, (15 mg/kg). A single dose of DOX significantly increased mRNA expression of TGF-β, Smad2, Smad4, CDKN2A and p53 and significantly decreased Samd7 and Mdm2 mRNA expression levels. Administration of DFX prior to DOX resulted in a complete reversal of DOX-induced alteration in cardiac enzymes and gene expression to normal levels. Data from this study suggest that (1) DOX induces its acute cardiotoxicity secondary to increasing genes expression of TGF-β/Smad pathway. (2) DOX increases apoptosis through upregulation of CDKN2A and p53 and downregulation of Mdm2 gene expression. (3) The preventive effect of DFX against DOX-induced cardiotoxicity is mediated via the TGF-β1/Smad pathway.
To mitigate the cardiotoxicity of anthracycline antibiotics without compromising their anticancer activities is still an issue to be solved. We previously demonstrated that schisandrin B (Sch B) could protect against doxorubicin (Dox)-induced acute cardiotoxicity via enhancing cardiomyocytic glutathione redox cycling that could attenuate oxidative stress generated from Dox. In this study, we attempted to prove if Sch B could also protect against Dox-induced chronic cardiotoxicity, a more clinically relevant issue, without compromising its anticancer activity.
Rat was given intragastrically either vehicle or Sch B (50 mg/kg) two hours prior to i.p. Dox (2.5 mg/kg) weekly over a 5-week period with a cumulative dose of Dox 12.5 mg/kg. At the 6th and 12th week after last dosing, rats were subjected to cardiac function measurement, and left ventricles were processed for histological and ultrastructural examination. Dox anticancer activity enhanced by Sch B was evaluated by growth inhibition of 4T1, a breast cancer cell line, and S180, a sarcoma cell line, in vitro and in vivo.
Pretreatment with Sch B significantly attenuated Dox-induced loss of cardiac function and damage of cardiomyocytic structure. Sch B substantially enhanced Dox cytotoxicities toward S180 in vitro and in vivo in mice, and increased Dox cytotoxcity against 4T1 in vitro. Although we did not observe this enhancement against the implanted 4T1 primary tumor, the spontaneous metastasis to lung was significantly reduced in combined treatment group than Dox alone group.
Sch B is capable of protecting Dox-induced chronic cardiotoxicity and enhancing its anticancer activity. To the best of our knowledge, Sch B is the only molecule ever proved to function as a cardioprotective agent as well as a chemotherapeutic sensitizer, which is potentially applicable for cancer treatment.
To study the preventive role of curcumin against doxorubicin (Dox)-induced myocardial toxicity in rats.
Materials and Methods:
Cardiotoxicity was produced by cumulative administration of Dox (15 mg/kg for two weeks). Curcumin (200 mg/kg, po) was administered as pretreatment for two weeks and then for two alternate weeks with Dox. The general observations, mortality, histopathology, biomarker enzymes like lactate dehydrogenase (LDH) and creatine phosphokinase (CPK), biochemical parameters such as aspartate aminotransferase (AST) alanine aminotransferase (ALT) and alkaline phosphatase (ALP), antioxidant enzymes such as glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were monitored after three weeks of last dose.
The repeated administration of Dox induced cardiomyopathy associated with an antioxidant deficit and increased level biomarkers. Pretreatment with the curcumin significantly protected myocardium from the toxic effects of Dox by reducing the elevated level of biomarker enzymes like LDH and CPK and biochemical parameters such as AST, ALT and ALP back to normal. Curcumin increased the reduced level of GSH, SOD and CAT and decreased the elevated level of malondialdehyde (MDA) in cardiac tissue.
The biochemical and histopathology reports support the cardioprotective effect of curcumin which could be attributed to antioxidant.
Antioxidant; cardiotoxicity; curcumin; doxorubicin; free radicals
The repercussion of the heated dispute on cyclooxygenase-2 (COX-2) selective nonsteroidal anti-inflammatory drugs (NSAIDs) led to the national and international withdrawal of several of the recently introduced coxibs. Further debate and research have highlighted risks of the classical NSAIDs too. There is much controversy about the cardiovascular safety of a nonselective NSAID naproxen (NAP) and its possible cardioprotective effect.
The study was undertaken to determine the cardiovascular effects of NAP on doxorubicin-induced cardiomyopathy in rats.
Materials and Methods:
Male albino rats received a single i.p. injection of normal saline (normal control group) and doxorubicin (DOX) 15 mg/kg (toxic control group). Naproxen was administered alone (50 mg/kg/day, p.o.) and in combination with DOX and DOX + trimetazidine (TMZ) (10 mg/kg/day, p.o.) for 5 days after 24 h of DOX treatment. DOX-induced cardiomyopathy was assessed in terms of increased activities of serum lactate dehydrogenase (LDH), tissue thiobarbituric acid reactive substances (TBARS) and decreased activities of myocardial glutathione, superoxide dismutase and catalase, followed by transmission electron microscopy of the cardiac tissue.
Doxorubicin significantly increased oxidative stress as evidenced by increased levels of LDH and TBARS and decreased antioxidant enzymes levels. Both biochemical and electron microscopic studies revealed that NAP itself was cardiotoxic and aggravated DOX-induced cardiomyopathy and abolished the protective effect of TMZ in rats.
This study indicates that NAP has the potential to worsen the situation in patients with cardiovascular disease. Therefore, it should be used cautiously in patients with compromised cardiac function.
Apoptosis; cardiomyopathy; enzyme (kinetics); free radicals; nonsteroidal anti-inflammatory drugs
Doxorubicin (DOX) is one of the most widely used and successful antitumor drugs, but its cumulative and dose-dependent cardiac toxicity has been the major concern of oncologists in cancer therapeutic practice for decades. With the increasing population of cancer survivals, there is a growing need to develop preventive strategies and effective therapies against DOX-induced cardiotoxicity, in particular, the late onset cardiomyopathy. Although intensive investigations on the DOX-induced cardiotoxicity have been continued for decades, the underlying mechanisms responsible for DOX-induced cardiotoxicity have not been completely elucidated. A rapidly expanding body of evidence supports that cardiomyocyte death by apoptosis and necrosis is a primary mechanism of DOX-induced cardiomyopathy and other types of cell death, such as autophagy and senescence/aging, may participate in this process. In this review, we will focus on the current understanding of molecular mechanisms underlying DOX-induced cardiomyocyte death, including the major primary mechanism of excess production of reactive oxygen species (ROS) and other recently discovered ROS-independent mechanisms. Different sensitivity to DOX-induced cell death signals between adult and young cardiomyocytes will also be discussed.
cardiomyocyte; doxorubicin; apoptosis; necrosis; autophagy
Doxorubicin (DOX) causes long-term cardiomyopathy that is dependent on oxidative stress and contractility disorders. Tirapazamine (TP), an experimental adjuvant drug, passes the same red-ox transformation as DOX. The aim of the study was to evaluate an effect of tirapazamine on oxidative stress, contractile protein level, and cardiomyocyte necrosis in rats administered doxorubicin. Rats were intraperitoneally injected six times once a week with tirapazamine in two doses, 5 (5TP) and 10 mg/kg (10TP), while doxorubicin was administered in dose 1.8 mg/kg (DOX). Subsequent two groups received both drugs simultaneously (5TP+DOX and 10TP+DOX). Tirapazamine reduced heart lipid peroxidation and normalised RyR2 protein level altered by doxorubicin. There were no significant changes in GSH/GSSG ratio, total glutathione, cTnI, AST, and SERCA2 level between DOX and TP+DOX groups. Cardiomyocyte necrosis was observed in groups 10TP and 10TP+DOX.
Doxorubicin-induced cardiotoxicity is widely known to occur at cumulative doses exceeding 450 mg/m2. However, very few studies have reported incidence of cardiac dysfunction in patients on chemotherapy with lower cumulative doses. To the best of our knowledge, there is no study carried out so far that has reported the incidence of cardiac dysfunction in adult Indian patients receiving doxorubicin. This study was undertaken to determine the incidence of doxorubicin-induced cardiotoxicity by serial resting echocardiography in patients on chemotherapy and identify risk factors associated with cardiotoxicity.
Materials and Methods:
Patients that were started on doxorubicin-based chemotherapy in the period from January 2000 to June 2001 and had completed at least 300 mg/m2 cumulative dose were taken in the study. Electrocardiography, chest X-ray and echocardiography were done at baseline, at 300 mg/m2 and at 450 mg/m2 cumulative doses of doxorubicin. All patients were evaluated for the presence of the following risk factors: Age>70 years, female sex, preexisting cardiac disease, hypertension, chest wall irradiation, body mass index (BMI)<20 kg/m2 , Karnofsky performance status, combination chemotherapy with cyclophosphamide and presence of liver disease. Subclinical cardiac dysfunction was defined as ejection fraction fall greater than 10% on follow-up echocardiography.
Thirty patients satisfied the criterion for being considered for evaluation. One (3%) patient developed congestive cardiac failure, while 8 (27%) patients developed subclinical cardiac dysfunction. Concomitant use of cyclophosphamide significantly increased the risk of cardiac dysfunction (P = 0.048), while low BMI (<20 kg/m2) and preexisting cardiac disease showed a trend towards increased risk of cardiac dysfunction (P = 0.07 for both).
Twenty-seven percent of the patients developed subclinical cardiac dysfunction in the cumulative dose range of 300-450 mg/m2 . This entails regular monitoring for cardiac dysfunction by echocardiography during treatment.
Doxurubicin; cardiotoxicity; echocardiographic monitoring
Doxorubicin (DOX) is used to treat childhood and adult cancer. DOX treatment is associated with both acute and chronic cardiotoxicity. The cardiotoxic effects of DOX are cumulative, limiting its chemotherapeutic dose. Free radical generation and p53-dependent apoptosis are thought to contribute to DOX-induced cardiotoxicity.
Methods and Results
Adult transgenic (MHC-CB7) mice expressing cardiomyocyte-restricted dominant-interfering p53 and their non-transgenic (NON-TXG) littermates were treated with DOX (20 mg/kg cumulative dose). NON-TXG mice exhibited reduced left ventricular (LV) systolic function (pre-DOX Fractional Shortening, FS, = 61 ± 2%, post-DOX FS = 45 ± 2%, mean +/- SEM, p<0.008), reduced cardiac mass, and high levels of cardiomyocyte apoptosis 7 days after the initiation of DOX treatment. In contrast, DOX-treated MHC-CB7 mice exhibited normal LV systolic function (pre-DOX FS = 63 ± 2%, post-DOX FS = 60 ± 2%, p>0.008), normal cardiac mass, and low levels of cardiomyocyte apoptosis. Western blot analyses indicated mTOR signaling was inhibited in DOX-treated NON-TXG mice, but not in DOX-treated MHC-CB7 mice. Accordingly, transgenic mice with cardiomyocyte-restricted constitutively active mTOR expression (MHC-mTORca) were studied. LV systolic function (pre-DOX FS = 64 +/- 2%, post-DOX FS 60 +/- 3%, p>0.008) and cardiac mass were normal in DOX-treated MHC-mTORca mice, despite similar levels of cardiomyocyte apoptosis as seen in DOX-treated NON-TXG mice.
These data suggest that DOX treatment induces acute cardiac dysfunction and reduces cardiac mass via p53-dependent inhibition of mTOR signaling, and that loss of myocardial mass, and not cardiomyocyte apoptosis, is the major contributor to acute DOX cardiotoxicity.
heart failure; apoptosis; myocytes
Increased oxidative stress is involved in the pathogenesis of diabetic nephropathy and neuropathy. Angiotensin II is a know factor in the pathogenesis of diabetic complications. The protective effects of ACEIs is known in diabetic nephropathy. Thus, Angiotensin receptor antagonists may have the same role. In this study, possible antidiabetic effect of Telmisartan and its tissues antioxidant effect in (STZ) induced diabetic rats, were studied
The present study was done on 40 rats. They were divided into 2 main groups. Group I: 10 rats as control group, received distilled water. Group II: 30 rats subdivided into 3 equal subgroups as follow: Subgroup IIA: control diabetic group, received 55 mg/kg STZ intraperitoneally. Sub group IIB: diabetic rats, received 10 mg/kg telmisartan daily intragastrically. Sub group IIC: diabetic rats received 10mg/kg gliclazide daily intragastrically. Diabetes was induced by intraperitoneal injection of 55 mg/kg STZ for 8 weeks evidenced by significant increase in serum glucose, HBA1c and decreased Hb levels.
Diabetic rats showed a significant increase in tissue TBARs and a significant decrease in tissue (GSH) and (SOD) enzymes. Telmisartan or Gliclazide in diabetic rats produced a beneficial effect on serum glucose, Hb, HBA1c and restored tissue GSH and SOD with a fall in tissues TBARS.
Telmisartan might be proved useful in the treatment of diabetes and its complications, as Gliclazide is restricted by its secondary failure rate and side effects.
Doxorubicin (DOX) is considered as one of the best antineoplastic agents. However, its clinical use is restricted by its associated cardiotoxicity, which is mediated by the production of reactive oxygen species. In this study, 20(S)-ginsenoside Rh2 (Rh2) was explored whether it had protective effects against DOX-induced cardiotoxicity. In vitro study on H9C2 cell line, as well as in vivo investigation in one mouse and one rat model of DOX-induced cardiomyopathy, was carried out. The results showed that pretreatment with Rh2 significantly increased the viability of DOX-injured H9C2 cells. In the mouse model, Rh2 could suppress the DOX-induced release of the cardiac enzymes into serum and improved the occurred pathological changes through ameliorating the decreased antioxidant biomolecules and the cumulated lipid peroxidation malondialdehyde in heart tissues. In the rat model, Rh2 could attenuate the change of ECG resulting from DOX administration. Furthermore, Rh2 enhanced the antitumor activity of DOX in A549 cells. Our findings thus demonstrated that Rh2 pretreatment could effectively alleviate heart injury induced by DOX, and Rh2 might act as a novel protective agent in the clinical usefulness of DOX.
Doxorubicin (DOX) is the most active cytotoxic agents having efficacy in malignancies either alone or combined with other cytocidal agents. The clinical usefulness of the anthracycline drug has been precluded by cardiac toxicity. Many therapeutic interventions have been attempted to improve the therapeutic benefits of the drug. This study is based on the possible protective effects of combination of p-coumaric acid (PC) and naringenin (NR) on DOX induced cardiac toxicity in male Swiss albino rats.
Total nine groups of Swiss albino rats were used, Group I (vehicle control) receive saline solution daily and Group II (disease control) receive saline solution daily up to 29th day and at 30th day a single dose of DOX (15 mg/kg i.p.) is given. PC alone (100 mg/kg/day p.o.) and (200 mg/kg/day p.o.) also NR alone (15 mg/kg/day) orally administer for 30 days. Similarly a standard drug Vit. E (100 mg/kg/day) administers alone for 30 days. Group PC/DOX and PC and NR/DOX receive PC (200 mg/kg/day) and combine PC (200 mg/kg/day).
Doxorubicin induced marked biochemical alterations characteristic of cardiac toxicity including increase in MDA level and decrease SOD, CAT & GSH level but prior administration of combination of PC & NR ahead of doxorubicin challenge ameliorated all these biochemical markers.
The study proves the beneficial effects of combination of PC and NR in protecting animal against DOX induced cardiotoxicity.
Antioxidents; cardiotoxicity; doxorubicine; naringenin; p-coumaric acid
Doxorubicin is one of the most effective anti-cancer drugs but its use is limited by cumulative cardiotoxicity that restricts lifetime dose. Redox damage is one of the most accepted mechanisms of toxicity, but not fully substantiated. Moreover doxorubicin is not an efficient redox cycling compound due to its low redox potential. Here we used genomic and chemical systems approaches in vivo to investigate the mechanisms of doxorubicin cardiotoxicity, and specifically test the hypothesis of redox cycling mediated cardiotoxicity.
Mice were treated with an acute dose of either doxorubicin (DOX) (15 mg/kg) or 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) (25 mg/kg). DMNQ is a more efficient redox cycling agent than DOX but unlike DOX has limited ability to inhibit gene transcription and DNA replication. This allowed specific testing of the redox hypothesis for cardiotoxicity. An acute dose was used to avoid pathophysiological effects in the genomic analysis. However similar data were obtained with a chronic model, but are not specifically presented. All data are deposited in the Gene Expression Omnibus (GEO). Pathway and biochemical analysis of cardiac global gene transcription and mRNA translation data derived at time points from 5 min after an acute exposure in vivo showed a pronounced effect on electron transport chain activity. This led to loss of ATP, increased AMPK expression, mitochondrial genome amplification and activation of caspase 3. No data gathered with either compound indicated general redox damage, though site specific redox damage in mitochondria cannot be entirely discounted.
These data indicate the major mechanism of doxorubicin cardiotoxicity is via damage or inhibition of the electron transport chain and not general redox stress. There is a rapid response at transcriptional and translational level of many of the genes coding for proteins of the electron transport chain complexes. Still though ATP loss occurs with activation caspase 3 and these events probably account for the heart damage.
Doxorubicin (Dox) is one of the most effective chemotherapeutic agents; however, it causes dose-dependent cardiotoxicity. Evaluation of left ventricular function relies on measurements based on M-mode echocardiography. A new technique based on quantification of myocardial motion and deformation, strain echocardiography, has been showed promising profile for early detection of cardiac dysfunction. Different therapy strategies, such as flavonoid plant extracts and stem cells, have been investigated to improve heart function in toxic cardiomyopathy. This work aimed to assess early cardiac function improvement after treatments with either flavonoid extract from Camellia sinensis or mesenchymal stem cells in Dox cardiotoxicity using strain echocardiography. Twenty Wistar rats were randomly assigned to four groups. They received water (control, Dox, Dox + stem cells) or 100 mg/kg C. sinensis extract (Dox + C. sinensis) via gavage, daily, for four weeks. Animals also received saline (control) or 5 mg/kg doxorubicin (Dox, Dox + C. sinensis, Dox + stem cells) via intraperitoneal injection, weekly, for four weeks. Stem cells were injected (3 × 106 cells) through tail vein prior the beginning of the experiment (Dox + stem cells). Animals were evaluated by hematological, electrocardiography, echocardiography, and histopathological examinations. Dox cardiotoxicity was only diagnosed with strain echocardiography, detecting a decrease in ventricular function. C. sinensis extract did not prevent ventricular dysfunction induced by Dox. However, strain echocardiography examination revealed that Dox cardiotoxicity was significantly suppressed in rats treated with stem cells. In conclusion, strain echocardiography was able to detect precocity signs of heart failure and stem cell therapy showed cardioprotection effect against Dox cardiotoxicity.
Echocardiography; Cardiotoxicity; Stem cell therapy; Flavonoid
Doxorubicin is one of the most effective chemotherapeutic agents; however, it causes dose-dependent cardiomyopathy that may lead to heart failure. Conventional measures of ventricular function, such as fractional shortening, are insensitive in detecting early doxorubicin cardiomyopathy. We tested whether novel 2-dimensional radial strain echocardiography (2DSE) can detect early doxorubicin injury following chronic administration in a rat model. 14 male Sprague Dawley rats (240−260 g) received doxorubicin 2.5 mg/k IV per week for 10 (n=4) or 12 weeks (n=10); 17 controls received saline (10 weeks, n=7 and 12 weeks, n=10). Serial 2DSE from 0−12 weeks was done at the mid left ventricle using Vivid 7 echo (General Electric, Waukesha, WI, USA). With Q analysis software, radial strain was obtained. From the 2D image, anatomical M-mode through the anterior/inferior walls was used to measure fractional shortening. Fibrosis (Masson's trichrome) and caspase-3 activity were measured from excised hearts. Radial strain was lower in the doxorubicin group (12 week: 26.7±3 vs. 38.3±2.6%, p=0.006), with significant difference by 8 weeks whereas fractional shortening was lower with doxorubicin only after 12 weeks (30.2±1.7 vs. 37.6±1.4%, p=0.02). Doxorubicin group had lower cardiac mass (0.85±0.09 vs. 1.14±0.04 g, p=0.001), higher caspase-3 activity (1.95±0.2 fold increase over control, p<0.0001) and fibrosis (3.9±0.7 vs. 0.7±0.1%, p=0.005). Radial strain was related directly to cardiac mass (R=0.61, p=0.0007) and inversely to caspase-3 activity (R=−0.5, p=0.005). 2-dimensional radial strain echocardiography is useful in the early detection of doxorubicin cardiac injury and the reduction in radial strain is associated with histologic markers of doxorubicin cardiomyopathy.
echocardiography; cardiomyopathy; heart failure; ventricular function; apoptosis
To investigate the preventive and curative role of ascorbic acid on doxorubicin (dox)-induced myocardial toxicity in rats.
Materials and Methods:
Animals were divided into five groups of six animals each. Group I served as normal control and received saline 5 ml/kg/day intraperitoneal (i.p.) for a period of 15 days. Group II animals received ascorbic acid 20 mg/kg per oral (p.o.) for 15 days as a pretreatment control (PR). Group III animals received dox 2.5 mg/kg body weight (b.w.), i.p., in six equal injections for two weeks for a total cumulative dose of 15 mg/kg b.w. Group IV animals received ascorbic acid 20 mg/kg p.o. for 15 days as a pretreatment followed by dox 2.5 mg/kg b.w., i.p., in six equal injections for two weeks for a total cumulative dose of 15 mg/kg body weight. Group V animals received dox 2.5 mg/kg b.w., i.p., in six equal injections for two weeks for a total cumulative dose of 15 mg/kg b.w. followed by ascorbic acid 20 mg/kg p.o for 15 days as post-treatment control (CR). The biochemical parameters such as tissue glutathione (GSH), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD), and enzyme biomarkers such as creatine phosphokinase (CPK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were monitored.
Pretreatment with ascorbic acid (20 mg/kg p.o.) significantly protected the myocardium from the toxic effect of dox (PR), by increasing the levels of antioxidant enzymes such as GSH, SOD, and CAT toward normal and decreased the levels of MDA, CPK, LDH, AST, and ALT as compared with dox-treated rats. Post-treatment with ascorbic acid to dox-treated group (CR) significantly increased the levels of tissue GSH, SOD, CAT and significantly decreased the level of MDA as compared with dox-treated group. It also reduced the severity of cellular damage of the myocardium as confirmed by histopathology. The restoration of the endogenous antioxidant system clearly depicts that ascorbic acid produced its protective effect by scavenging the reactive oxygen species.
The results obtained in this study provide evidence for the usefulness of the ascorbic acid as a cardioprotective agent.
Ascorbic acid; cardiotoxicity; doxorubicin; free radicals
The cardiotoxicity of doxorubicin limits its clinical use in the treatment of a variety of malignancies. Previous studies suggest that doxorubicin-associated cardiotoxicity is mediated by reactive oxygen species (ROS)-induced apoptosis. We therefore investigated if baicalein, a natural antioxidant component of Scutellaria baicalensis, could attenuate ROS generation and cell death induced by doxorubicin. Using an established chick cardiomyocyte model, doxorubicin (10 μM) increased cell death in a concentration- and time-dependent manner. ROS generation was increased in a dose-response fashion and associated with loss of mitochondrial membrane potential. Doxorubicin also augmented DNA fragmentation and increased the phosphorylation of ROS-sensitive pro-apoptotic kinase c-Jun N-terminal kinase (JNK). Adjunct treatment of baicalein (25 μM) and doxorubicin for 24 h significantly reduced both ROS generation (587 ± 89 a.u. vs. 932 a.u. ± 121 a.u., P < 0.01) and cell death (30.6 ± 5.1% vs. 46.8 ± 8.3%, P < 0.01). The dissipated mitochondrial potential and increased DNA fragmentation were also ameliorated. Along with the reduction of ROS and apoptosis, baicalein attenuated phosphorylation of JNK induced by doxorubicin (1.7 ± 0.3 vs. 3.0 ± 0.4 fold, P < 0.05). Co-treatment of cardiomyocytes with doxorubicin and JNK inhibitor SP600125 (10 μM; 24 h) reduced JNK phosphorylation and enhanced cell survival, suggesting that the baicalein protection against doxorubicin cardiotoxicity was mediated by JNK activation. Importantly, concurrent baicalein treatment did not interfere with the anti-proliferative effects of doxorubicin in human breast cancer MCF-7 cells. In conclusion, baicalein adjunct treatment confers anti-apoptotic protection against doxorubicin-induced cardiotoxicity without compromising its anti-cancer efficacy.
BAICALEIN; DOXORUBICIN; OXIDATIVE STRESS; APOPTOSIS; JNK; ANTIPROLIFERATIVE EFFECT
Doxorubicin (DOX) is associated with premature cardiovascular events including myocardial infarction. This study was performed to determine if the weekly administration of DOX influenced coronary arteriolar medial and/or adventitial wall thickening.
Thirty-two male Sprague-Dawley rats aged 25.1± 2.4 weeks were randomly divided into three groups and received weekly intraperitoneal injections of normal saline (saline, n = 7), or low (1.5 mg/kg to 1.75 mg/kg, n = 14) or high (2.5 mg/kg, n = 11) doses of DOX. The animals were treated for 2–12 weeks, and euthanized at pre-specified intervals (2, 4, 7, or 10+ weeks) to obtain histopathologic assessments of coronary arteriolar lumen diameter, medial wall thickness, adventitial wall thickness, and total wall thickness (medial thickness + adventitial thickness).
Lumen diameter was similar across all groups (saline: 315±34 µm, low DOX: 286±24 µm, high DOX: 242±27 µm; p = 0.22). In comparison to animals receiving weekly saline, animals receiving weekly injections of 2.5 mg/kg of DOX experienced an increase in medial (23±2µm vs. 13±3µm; p = 0.005), and total wall thickness (51±4µm vs. 36±5µm; p = 0.022), respectively. These increases, as well as adventitial thickening became more prominent after normalizing for lumen diameter (p<0.05 to p<0.001) and after adjusting for age, weight, and total cumulative DOX dose (p = 0.02 to p = 0.01). Animals receiving low dose DOX trended toward increases in adventitial and total wall thickness after normalization to lumen diameter and accounting for age, weight, and total cumulative DOX dose (p = 0.06 and 0.09, respectively).
In conclusion, these data demonstrate that weekly treatment of rats with higher doses of DOX increases coronary arteriolar medial, adventitial, and total wall thickness. Future studies are warranted to determine if DOX related coronary arteriolar effects are reversible or preventable, exacerbate the known cardiomyopathic effects of DOX, influence altered resting or stress-induced myocardial perfusion, or contribute to the occurrence of myocardial infarction.
The clinical use of doxorubicin (DOX), a potent antineoplastic agent, is limited by its serious side-effects, which include acute and chronic cumulative dose-related cardiotoxicity. Berberine (BER), a botanical alkaloid, has been reported to possess cardioprotective and antitumor effects. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-tetrazolium bromide (MTT) assay was used to detect the cell viability of A549, HeLa and HepG2 cells after each cell line was treated with DOX, BER or a combination of DOX and BER for 24 h. Apoptosis was evaluated by acridine orange staining. The results showed that BER and DOX exhibited dose-dependent inhibitory effects on A549 and HeLa cells which were likely mediated by inducing apoptosis. The same result was found in the combination group. Isobologram illustration and combination index (CI) analyses revealed that the combination of DOX and BER generates synergistic effects in A549 (CI=0.61) and HeLa (CI=0.73) cells. These findings indicate that BER sensitizes cells to the anticancer effects of DOX.
berberine; doxorubicin; synergistic effect; A549; HeLa
The anthracycline doxorubicin (DOX) is an effective chemotherapeutic agent used to treat pediatric cancers, but is associated with cardiotoxicity which can manifest many years after the initial exposure. To date, very little is known about the mechanism of this late onset cardiotoxicity.
Methods and Results
To understand this problem, we developed a pediatric model of late onset DOX-induced cardiotoxicity, where juvenile mice were exposed to DOX, using a cumulative dose that did not induce acute cardiotoxicity. These mice developed normally and had no obvious cardiac abnormalities as adults. However, evaluation of the vasculature revealed that juvenile DOX exposure impaired vascular development resulting in abnormal vascular architecture in the hearts with less branching and decreased capillary density. Both physiological and pathological stress induced late onset cardiotoxicity in the adult DOX mice. Moreover, adult mice subjected to myocardial infarction (MI) developed rapid heart failure which correlated with a failure to increase capillary density in the injured area. Progenitor cells participate in regeneration and blood vessel formation after an MI, but DOX mice had fewer progenitor cells in the infarct border zone. Interestingly, DOX treatment reduced proliferation and differentiation of the progenitor cells into cells of cardiac lineages.
Our data suggest that anthracycline treatment impairs vascular development as well as progenitor cell function in the young heart, resulting in an adult heart that is more susceptible to stress.
anthracyclines; heart failure; vascularization; cardiac progenitor cells
Doxorubicin (DOX) is a potent anti-tumor agent. DOX can also induce cardiotoxicity, and high cumulative doses are associated with recalcitrant heart failure. Children are particularly sensitive to DOX-induced heart failure. The ability to genetically modify mice makes them an ideal experimental system to study the molecular basis of DOX-induced cardiotoxicity. However, most mouse DOX studies rely on acute drug administration in adult animals, which typically are analyzed within one week. Here we describe a juvenile mouse model of chronic DOX-induced cardiac dysfunction. DOX treatment was initiated at 2 weeks of age and continued for a period of 5 weeks (25 mg/kg cumulative dose). This resulted in a decline in cardiac systolic function, which was accompanied by marked atrophy of the heart, low levels of cardiomyocyte apoptosis, and decreased growth velocity. Other animals were allowed to recover for 13 weeks following the final DOX injection. Cardiac systolic function improved during this recovery period but remained depressed as compared to the saline injected controls, despite the reversal of cardiac atrophy. Interestingly, increased levels of cardiomyocyte apoptosis and concomitant myocardial fibrosis were observed following DOX withdrawal. These data suggest that different mechanisms contribute to cardiac dysfunction during the treatment and recovery phases.
heart failure; chemotherapy; genetically modified mice
The clinical use of doxorubicin, an anthracycline chemotherapeutic agent, is limited by cardiotoxicity, particularly when combined with herceptin, an antibody that blocks the HER2 receptor. Doxorubicin induces cyclooxygenase–2 (COX-2) activity in rat neonatal cardiomyocytes. This expression of COX-2 limits doxorubicin-induced cardiac cell injury, raising the possibility that the administration of a prostaglandin may protect the heart during the in vivo administration of doxorubicin. Doxorubicin (15 mg/kg) administered to adult male Sprague Dawley rats induced COX-2 expression and activity in cardiac tissue. Prostacyclin generation measured as the excretion of 2,3-dinor-6-keto-PGF1α also increased, and this was blocked by a COX-2 inhibitor, SC236. In contrast, administration of a COX-1 inhibitor SC560 at a dose that reduced serum thromboxane B2 by more than 80% did not prevent the doxorubicin-induced increase in prostacyclin generation. Doxorubicin increased cardiac injury, detected as a rise in plasma cardiac troponin T, serum lactate dehydrogenase, and cardiomyocyte apoptosis; this was aggravated by coadministration of SC236 but not SC560. The degree of injury in animals treated with a combination of doxorubicin and SC236 was attenuated by prior administration of the prostacyclin analogue iloprost. These data raise the possibility of protecting the heart during the administration of doxorubicin by prior administration of prostacyclin.