Glutathione S-transferase overexpression protects against anthracycline-induced H9C2 cell death

The Critical Assessment of Oxidative Stress Parameters as Potential Biomarkers of Carbon Monoxide Poisoning

In conventional clinical toxicology practice, the blood level of carboxyhemoglobin is a biomarker of carbon monoxide (CO) poisoning but does not correspond to the complete clinical picture and the severity of the poisoning. Taking into account articles suggesting the relationship between oxidative stress parameters and CO poisoning, it seems reasonable to consider this topic more broadly, including experimental biochemical data (oxidative stress parameters) and patients poisoned with CO. This article aimed to critically assess oxidative-stress-related parameters as potential biomarkers to evaluate the severity of CO poisoning and their possible role in the decision to treat. The critically set parameters were antioxidative, including catalase, 2,2-diphenyl-1-picryl-hydrazyl, glutathione, thiol and carbonyl groups. Our preliminary studies involved patients (n = 82) admitted to the Toxicology Clinical Department of the University Hospital of Jagiellonian University Medical College (Kraków, Poland) during 2015-2020. The poisoning was diagnosed based on medical history, clinical symptoms, and carboxyhemoglobin blood level. Blood samples for carboxyhemoglobin and antioxidative parameters were collected immediately after admission to the emergency department. To evaluate the severity of the poisoning, the Pach scale was applied. The final analysis included a significant decrease in catalase activity and a reduction in glutathione level in all poisoned patients based on the severity of the Pach scale: I°-III° compared to the control group. It follows from the experimental data that the poisoned patients had a significant increase in level due to thiol groups and the 2,2-diphenyl-1-picryl-hydrazyl radical, with no significant differences according to the severity of poisoning. The catalase-to-glutathione and thiol-to-glutathione ratios showed the most important differences between the poisoned patients and the control group, with a significant increase in the poisoned group. The ratios did not differentiate the severity of the poisoning. The carbonyl level was highest in the control group compared to the poisoned group but was not statistically significant. Our critical assessment shows that using oxidative-stress-related parameters to evaluate the severity of CO poisoning, the outcome, and treatment options is challenging.

Pediatric Acute Promyelocytic Leukemia: Epidemiology, Molecular Features, and Importance of GST-Theta 1 in Chemotherapy Response and Outcome

Previous studies have suggested a variation in the incidence of acute promyelocytic leukemia (APL) among the geographic regions with relatively higher percentages in the Latin American population. We aimed to explore the population burden of pediatric APL, gathering information from the population-based cancer registry (PBCR) and the diagnosis of APL obtained through incident cases from a hospital-based cohort. The homozygous deletion in glutathione S-transferases (GSTs) leads to a loss of enzyme detoxification activity, possibly affecting the treatment response. Mutations in the RAS pathway genes are also considered to be a key component of the disease both in the pathogenesis and in the outcomes. We have assessed mutations in a RAS-MAP kinase pathway (FLT3, PTPN11, and K-/NRAS) and GST variant predisposition risk in the outcome. Out of the 805 children and adolescents with acute myeloid leukemia (AML) who are registered in the PBCR, 35 (4.3%) were APL cases. The age-adjusted incidence rate (AAIR) was 0.03 per 100,000 person-years. One-hundred and sixty-three patients with APL were studied out of 931 AML cases (17.5%) from a hospital-based cohort. Mutations in FLT3, KRAS, and NRAS accounted for 52.1% of the cases. Patients with APL presented a 5-year probability of the overall survival (OS) of 67.3 ± 5.8%. A GST-theta 1 (GSTT1) null genotype conferred adverse prognosis, with an estimated hazard ratio of 2.8, 95% confidence interval (CI) 1.2-6.9. We speculate that the GSTT1 polymorphism is associated with therapeutics and would allow better OS of patients with APL with a GSTT1 null genotype.

Protective Role of Freshwater and Marine Rotifer Glutathione S-Transferase Sigma and Omega Isoforms Transformed into Heavy Metal-Exposed Escherichia coli

Glutathione S-transferases (GSTs) play an important role in phase II of detoxification to protect cells in response to oxidative stress generated by exogenous toxicants. Despite their important role in defense, studies on invertebrate GSTs have mainly focused on identification and characterization. Here, we isolated omega and sigma classes of GSTs from the freshwater rotifer Brachionus calyciflorus and the marine rotifer Brachionus koreanus and explored their antioxidant function in response to metal-induced oxidative stress. The recombinant Bc- and Bk-GSTs were successfully transformed and expressed in Escherichia coli. Their antioxidant potential was characterized by measuring kinetic properties and enzymatic activity in response to pH, temperature, and chemical inhibitor. In addition, a disk diffusion assay, reactive oxygen species assay, and morphological analysis revealed that GST transformed into E. coli significantly protected cells from oxidative stress induced by H₂O₂ and metals (Hg, Cd, Cu, and Zn). Stronger antioxidant activity was exhibited by GST-S compared to GST-O in both rotifers, suggesting that GST-S plays a prominent function as an antioxidant defense mechanism in Brachionus spp. Overall, our study clearly shows the antioxidant role of Bk- and Bc-GSTs in E. coli and provides a greater understanding of GST class-specific and interspecific detoxification in rotifer Brachionus spp.

Chlorogenic acid analogues from Gynura nepalensis protect H9c2 cardiomyoblasts against H2O2-induced apoptosis

AIM

Chlorogenic acid has shown protective effect on cardiomyocytes against oxidative stress-induced damage. Herein, we evaluated nine caffeoylquinic acid analogues (1-9) isolated from the leaves of Gynura nepalensis for their protective effect against H₂O₂-induced H9c2 cardiomyoblast damage and explored the underlying mechanisms.

METHODS

H9c2 cardiomyoblasts were exposed to H₂O₂ (0.3 mmol/L) for 3 h, and cell viability was detected with MTT assay. Hoechst 33342 staining was performed to evaluate cell apoptosis. MMPs (mitochondrial membrane potentials) were measured using a JC-1 assay kit, and ROS (reactive oxygen species) generation was measured using CM-H₂ DCFDA. The expression levels of relevant proteins were detected using Western blot analysis.

RESULTS

Exposure to H₂O₂ markedly decreased the viability of H9c2 cells and catalase activity, and increased LDH release and intracellular ROS production; accompanied by a loss of MMP and increased apoptotic rate. Among the 9 chlorogenic acid analogues as well as the positive control drug epigallocatechin gallate (EGCG) tested, compound 6 (3,5-dicaffeoylquinic acid ethyl ester) was the most effective in protecting H9c2 cells from H₂O₂-induced cell death. Pretreatment with compound 6 (1.56-100 μmol/L) dose-dependently alleviated all the H₂O₂-induced detrimental effects. Moreover, exposure to H₂O₂ significantly increased the levels of Bax, p53, cleaved caspase-8, and cleaved caspase-9, and decreased the level of Bcl-2, resulting in cell apoptosis. Exposure to H₂O₂ also significantly increased the phosphorylation of p38, JNK and ERK in the H9c2 cells. Pretreatment with compound 6 (12.5 and 25 μmol/L) dose-dependently inhibited the H₂O₂-induced increase in the level of cleaved caspase-9 but not of cleaved caspase-8. It also dose-dependently suppressed the H₂O₂-induced phosphorylation of JNK and ERK but not that of p38.

CONCLUSION

Compound 6 isolated from the leaves of Gynura nepalensis potently protects H9c2 cardiomyoblasts against H₂O₂-induced apoptosis, possibly by inhibiting intrinsic apoptosis and the ERK/JNK pathway.

Transcriptomic alterations in the heart of non-obese type 2 diabetic Goto-Kakizaki rats

Background

There is a spectacular rise in the global prevalence of type 2 diabetes mellitus (T2DM) due to the worldwide obesity epidemic. However, a significant proportion of T2DM patients are non-obese and they also have an increased risk of cardiovascular diseases. As the Goto-Kakizaki (GK) rat is a well-known model of non-obese T2DM, the goal of this study was to investigate the effect of non-obese T2DM on cardiac alterations of the transcriptome in GK rats.

Methods

Fasting blood glucose, serum insulin and cholesterol levels were measured at 7, 11, and 15 weeks of age in male GK and control rats. Oral glucose tolerance test and pancreatic insulin level measurements were performed at 11 weeks of age. At week 15, total RNA was isolated from the myocardium and assayed by rat oligonucleotide microarray for 41,012 genes, and then expression of selected genes was confirmed by qRT-PCR. Gene ontology and protein–protein network analyses were performed to demonstrate potentially characteristic gene alterations and key genes in non-obese T2DM.

Results

Fasting blood glucose, serum insulin and cholesterol levels were significantly increased, glucose tolerance and insulin sensitivity were significantly impaired in GK rats as compared to controls. In hearts of GK rats, 204 genes showed significant up-regulation and 303 genes showed down-regulation as compared to controls according to microarray analysis. Genes with significantly altered expression in the heart due to non-obese T2DM includes functional clusters of metabolism (e.g. Cyp2e1, Akr1b10), signal transduction (e.g. Dpp4, Stat3), receptors and ion channels (e.g. Sln, Chrng), membrane and structural proteins (e.g. Tnni1, Mylk2, Col8a1, Adam33), cell growth and differentiation (e.g. Gpc3, Jund), immune response (e.g. C3, C4a), and others (e.g. Lrp8, Msln, Klkc1, Epn3). Gene ontology analysis revealed several significantly enriched functional inter-relationships between genes influenced by non-obese T2DM. Protein–protein interaction analysis demonstrated that Stat is a potential key gene influenced by non-obese T2DM.

Conclusions

Non-obese T2DM alters cardiac gene expression profile. The altered genes may be involved in the development of cardiac pathologies and could be potential therapeutic targets in non-obese T2DM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0424-3) contains supplementary material, which is available to authorized users.

Metabolomics Analysis of Hormone-Responsive and Triple-Negative Breast Cancer Cell Responses to Paclitaxel Identify Key Metabolic Differences

To date, no targeted therapies are available to treat triple negative breast cancer (TNBC), while other breast cancer subtypes are responsive to current therapeutic treatment. Metabolomics was conducted to reveal differences in two hormone receptor-negative TNBC cell lines and two hormone receptor-positive Luminal A cell lines. Studies were conducted in the presence and absence of paclitaxel (Taxol). TNBC cell lines had higher levels of amino acids, branched-chain amino acids, nucleotides, and nucleotide sugars and lower levels of proliferation-related metabolites like choline compared with Luminal A cell lines. In the presence of paclitaxel, each cell line showed unique metabolic responses, with some similarities by type. For example, in the Luminal A cell lines, levels of lactate and creatine decreased while certain choline metabolites and myo-inositol increased with paclitaxel. In the TNBC cell lines levels of glutamine, glutamate, and glutathione increased, whereas lysine, proline, and valine decreased in the presence of drug. Profiling secreted inflammatory cytokines in the conditioned media demonstrated a greater response to paclitaxel in the hormone-positive Luminal cells compared with a secretion profile that suggested greater drug resistance in the TNBC cells. The most significant differences distinguishing the cell types based on pathway enrichment analyses were related to amino acid, lipid and carbohydrate metabolism pathways, whereas several biological pathways were differentiated between the cell lines following treatment.

Pharmacogenomics and the treatment of acute myeloid leukemia

Acute myeloid leukemia (AML) is a clinically and biologically heterogeneous malignancy that is primarily treated with combinations of cytarabine and anthracyclines. Although this scheme remains effective in most of the patients, variability of outcomes in patients has been partly related with their genetic variability. Several pharmacogenetic studies have analyzed the impact of polymorphisms in genes encoding transporters, metabolizers or molecular targets of chemotherapy agents. A systematic review on all eligible studies was carried out in order to estimate the effect of polymorphisms of anthracyclines and cytarabine pathways on efficacy and toxicity of AML treatment. Other emerging genes recently studied in AML, such as DNA repair genes, genes potentially related to chemotherapy response or AML prognosis, have also been included.

Genetic variants in SLC22A17 and SLC22A7 are associated with anthracycline-induced cardiotoxicity in children

AIM

To identify novel variants associated with anthracycline-induced cardiotoxicity and to assess these in a genotype-guided risk prediction model.

PATIENTS & METHODS

Two cohorts treated for childhood cancer (n = 344 and 218, respectively) were genotyped for 4578 SNPs in drug ADME and toxicity genes.

RESULTS

Significant associations were identified in SLC22A17 (rs4982753; p = 0.0078) and SLC22A7 (rs4149178; p = 0.0034), with replication in the second cohort (p = 0.0071 and 0.047, respectively). Additional evidence was found for SULT2B1 and several genes related to oxidative stress. Adding the SLC22 variants to the prediction model improved its discriminative ability (AUC 0.78 vs 0.75 [p = 0.029]).

CONCLUSION

Two novel variants in SLC22A17 and SLC22A7 were significantly associated with anthracycline-induced cardiotoxicity and improved a genotype-guided risk prediction model, which could improve patient risk stratification.

The effect of a preparation of minerals, vitamins and trace elements on the cardiac gene expression pattern in male diabetic rats

Background

Diabetic patients have an increased risk of developing cardiovascular diseases, which are the leading cause of death in developed countries. Although multivitamin products are widely used as dietary supplements, the effects of these products have not been investigated in the diabetic heart yet. Therefore, here we investigated if a preparation of different minerals, vitamins, and trace elements (MVT) affects the cardiac gene expression pattern in experimental diabetes.

Methods

Two-day old male Wistar rats were injected with streptozotocin (i.p. 100 mg/kg) or citrate buffer to induce diabetes. From weeks 4 to 12, rats were fed with a vehicle or a MVT preparation. Fasting blood glucose measurement and oral glucose tolerance test were performed at week 12, and then total RNA was isolated from the myocardium and assayed by rat oligonucleotide microarray for 41012 oligonucleotides.

Results

Significantly elevated fasting blood glucose concentration and impaired glucose tolerance were markedly improved by MVT-treatment in diabetic rats at week 12. Genes with significantly altered expression due to diabetes include functional clusters related to cardiac hypertrophy (e.g. caspase recruitment domain family, member 9; cytochrome P450, family 26, subfamily B, polypeptide; FXYD domain containing ion transport regulator 3), stress response (e.g. metallothionein 1a; metallothionein 2a; interleukin-6 receptor; heme oxygenase (decycling) 1; and glutathione S-transferase, theta 3), and hormones associated with insulin resistance (e.g. resistin; FK506 binding protein 5; galanin/GMAP prepropeptide). Moreover the expression of some other genes with no definite cardiac function was also changed such as e.g. similar to apolipoprotein L2; brain expressed X-linked 1; prostaglandin b2 synthase (brain). MVT-treatment in diabetic rats showed opposite gene expression changes in the cases of 19 genes associated with diabetic cardiomyopathy. In healthy hearts, MVT-treatment resulted in cardiac gene expression changes mostly related to immune response (e.g. complement factor B; complement component 4a; interferon regulatory factor 7; hepcidin).

Conclusions

MVT-treatment improved diagnostic markers of diabetes. This is the first demonstration that MVT-treatment significantly alters cardiac gene expression profile in both control and diabetic rats. Our results and further studies exploring the mechanistic role of individual genes may contribute to the prevention or diagnosis of cardiac complications in diabetes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-015-0248-6) contains supplementary material, which is available to authorized users.

The tell-tale heart: molecular and cellular responses to childhood anthracycline exposure

Since the modern era of cancer chemotherapy that began in the mid-1940s, survival rates for children afflicted with cancer have steadily improved from 10% to current rates that approach 80% (60). Unfortunately, many long-term survivors of pediatric cancer develop chemotherapy-related health effects; 25% are afflicted with a severe or life-threatening medical condition, with cardiovascular disease being a primary risk (96). Childhood cancer survivors have markedly elevated incidences of stroke, congestive heart failure (CHF), coronary artery disease, and valvular disease (96). Their cardiac mortality is 8.2 times higher than expected (93). Anthracyclines are a key component of most curative chemotherapeutic regimens used in pediatric cancer, and approximately half of all childhood cancer patients are exposed to them (78). Numerous epidemiologic and observational studies have linked childhood anthracycline exposure to an increased risk of developing cardiomyopathy and CHF, often decades after treatment. The acute toxic effects of anthracyclines on cardiomyocytes are well described; however, myocardial tissue is comprised of additional resident cell types, and events occurring in the cardiomyocyte do not fully explain the pathological processes leading to late cardiomyopathy and CHF. This review will summarize the current literature regarding the cellular and molecular responses to anthracyclines, with an important emphasis on nonmyocyte cardiac cell types as well as those that mediate the myocardial injury response.

Amelioration of adriamycin-induced cardiotoxicity by Salsola kali aqueous extract is mediated by lowering oxidative stress

OBJECTIVES

To assess the cardioprotective effect of the Salsola kali aqueous extract against adriamycin (ADR)-induced cardiotoxicity in male Swiss albino mice.

METHODS

The aqueous extract of S. kali was phytochemically screened by traditional methods for different classes and further evaluated for antioxidant activity in vitro. In vivo, cardioprotective evaluation of the extract was designed to have four groups of mice: (1) control group (distilled water, orally; normal saline, intraperitoneally (i.p.)); (2) ADR group (15 mg/kg, i.p.); (3) aqueous S. kali extract (200 mg/kg, orally); and (4) ADR + S. kali group. ADR (5 mg/kg) was injected three times over 2 weeks while S. kali was orally administered daily for 3 weeks (1 week before and 2 weeks during ADR treatment). Cardioprotective properties were assessed using biochemical and histopathological approaches.

RESULTS

ADR caused a significant increase in serum enzymes (lactate dehydrogenase, creatine phosphokinase, aspartate aminotransferase, and alanine aminotransferase). Myocardial levels of malondialdehyde, nitric oxide, and reduced glutathione, as well as the activities of superoxide dismutase and catalase increased while the activities of glutathione peroxidase and glutathione S-transferase declined. Histopathological examination of heart sections revealed that ADR caused myofibrils loss, necrosis and cytoplasmic vacuolization.

DISCUSSION

Pretreatment with S. kali aqueous extract normalized serum and antioxidant enzymes minimized lipid peroxidation and cardiac damage. These results have suggested that the extract has antioxidant activity, indicating that the mechanism of cardioprotection during ADR treatment is mediated by lowering oxidative stress.

Oxidative stress on cardiotoxicity after treatment with single and multiple doses of doxorubicin

The mechanism of doxorubicin (DOX)-induced cardiotoxicity remains controversial. Wistar rats ( n = 66) received DOX injections intraperitoneally and were randomly assigned to 2 experimental protocols: (1) rats were killed before (−24 h, n = 8) and 24 h after (+24 h, n = 8) a single dose of DOX (4 mg/kg body weight) to determine the DOX acute effect and (2) rats ( n = 58) received 4 injections of DOX (4 mg/kg body weight/week) and were killed before the first injection (M0) and 1 week after each injection (M1, M2, M3, and M4) to determine the chronological effects. Animals used at M0 ( n = 8) were also used at moment −24 h of acute study. Cardiac total antioxidant performance (TAP), DNA damage, and morphology analyses were carried out at each time point. Single dose of DOX was associated with increased cardiac disarrangement, necrosis, and DNA damage (strand breaks (SBs) and oxidized pyrimidines) and decreased TAP. The chronological study showed an effect of a cumulative dose on body weight ( R = −0.99, p = 0.011), necrosis ( R = 1.00, p = 0.004), TAP ( R = 0.95, p = 0.049), and DNA SBs ( R = −0.95, p = 0.049). DNA SBs damage was negatively associated with TAP ( R = −0.98, p = 0.018), and necrosis ( R = −0.97, p = 0.027). Our results suggest that oxidative damage is associated with acute cardiotoxicity induced by a single dose of DOX only. Increased resistance to the oxidative stress is plausible for the multiple dose of DOX. Thus, different mechanisms may be involved in acute toxicity versus chronic toxicity.

Complications of chemotherapy, a basic science update

Anthracyclines, discovered 50 years ago, are antibiotics widely used as antineoplastic agents and are among the most successful anticancer therapies ever developed to treat a wide range of cancers, including hematological malignancies, soft tissue sarcomas and solid tumors. However, some anthracyclines, including doxorubicin, exhibit major signs of cardiotoxicity that may ultimately lead to heart failure (HF). Despite intensive research on doxorubicine-induced cardiotoxicity, the underlying mechanisms responsible for doxorubicin-induced cardiotoxicity have not been fully elucidated yet. Published literature so far has focused mostly on mitochondria dysfunction with consequent oxidative stress, Ca(2+) overload, and cardiomyocyte death as doxorubicin side effects, leading to heart dysfunction. This review focuses on the current understanding of the molecular mechanisms underlying doxorubicin-induced cardiomyocyte death (i.e.: cardiomyocyte death, mitochondria metabolism and bioenergetic alteration), but we will also point to new directions of possible mechanisms, suggesting potent prior or concomitant alterations of specific signaling pathways with molecular actors directly targeted by the anticancer drugs itself (i.e. calcium homeostasis or cAMP signaling cascade). The mechanisms of anticancer cardiac toxicity may be more complex than just mitochondria dysfunction. Partnership of both basic and clinical research is needed to promote new strategies in diagnosis, therapies with concomitant cardioprotection in order to achieve cancer treatment with acceptable cardiotoxicity along life span.

The clinically relevant pharmacogenomic changes in acute myelogenous leukemia

Acute myelogenous leukemia (AML) is an extremely heterogeneous neoplasm with several clinical, pathological, genetic and molecular subtypes. Combinations of various doses and schedules of cytarabine and different anthracyclines have been the mainstay of treatment for all forms of AMLs in adult patients. Although this combination, with the addition of an occasional third agent, remains effective for treatment of some young-adult patients with de novo AML, the prognosis of AML secondary to myelodysplastic syndromes or myeloproliferative neoplasms, treatment-related AML, relapsed or refractory AML, and AML that occurs in older populations remains grim. Taken into account the heterogeneity of AML, one size does not and should not be tried to fit all. In this article, the authors review currently understood, applicable and relevant findings related to cytarabine and anthracycline drug-metabolizing enzymes and drug transporters in adult patients with AML. To provide a prime-time example of clinical applicability of pharmacogenomics in distinguishing a subset of patients with AML who might be better responders to farnesyltransferase inhibitors, the authors also reviewed findings related to a two-gene transcript signature consisting of high RASGRP1 and low APTX, the ratio of which appears to positively predict clinical response in AML patients treated with farnesyltransferase inhibitors.

Pummelo protects Doxorubicin-induced cardiac cell death by reducing oxidative stress, modifying glutathione transferase expression, and preventing cellular senescence

Citrus flavonoids have been shown to reduce cardiovascular disease (CVD) risks prominently due to their antioxidant effects. Here we investigated the protective effect of pummelo (Citrus maxima, CM) fruit juice in rat cardiac H9c2 cells against doxorubicin (DOX-) induced cytotoxicity. Four antioxidant compositions (ascorbic acid, hesperidin, naringin, and gallic acid) were determined by HPLC. CM significantly increased cardiac cell survival from DOX toxicity as evaluated by MTT assay. Reduction of cellular oxidative stress was monitored by the formation of DCF fluorescent product and total glutathione (GSH) levels. The changes in glutathione-S-transferase (GST) activity and expression were determined by enzyme activity assay and Western blot analysis, respectively. Influence of CM on senescence-associated β-galactosidase activity (SA-β-gal) was also determined. The mechanisms of cytoprotection involved reduction of intracellular oxidative stress, maintaining GSH availability, and enhanced GST enzyme activity and expression. DOX-induced cellular senescence was also attenuated by long-term CM treatment. Thus, CM fruit juice can be promoted as functional fruit to protect cells from oxidative cell death, enhance the phase II GSTP enzyme activity, and decrease senescence phenotype population induced by cardiotoxic agent such as DOX.

Metabolic syndrome influences cardiac gene expression pattern at the transcript level in male ZDF rats

BACKGROUND

Metabolic syndrome (coexisting visceral obesity, dyslipidemia, hyperglycemia, and hypertension) is a prominent risk factor for cardiovascular morbidity and mortality, however, its effect on cardiac gene expression pattern is unclear. Therefore, we examined the possible alterations in cardiac gene expression pattern in male Zucker Diabetic Fatty (ZDF) rats, a model of metabolic syndrome.

METHODS

Fasting blood glucose, serum insulin, cholesterol and triglyceride levels were measured at 6, 16, and 25 wk of age in male ZDF and lean control rats. Oral glucose tolerance test was performed at 16 and 25 wk of age. At week 25, total RNA was isolated from the myocardium and assayed by rat oligonucleotide microarray for 14921 genes. Expression of selected genes was confirmed by qRT-PCR.

RESULTS

Fasting blood glucose, serum insulin, cholesterol and triglyceride levels were significantly increased, glucose tolerance and insulin sensitivity were impaired in ZDF rats compared to leans. In hearts of ZDF rats, 36 genes showed significant up-regulation and 49 genes showed down-regulation as compared to lean controls. Genes with significantly altered expression in the heart due to metabolic syndrome includes functional clusters of metabolism (e.g. 3-hydroxy-3-methylglutaryl-Coenzyme A synthase 2; argininosuccinate synthetase; 2-amino-3-ketobutyrate-coenzyme A ligase), structural proteins (e.g. myosin IXA; aggrecan1), signal transduction (e.g. activating transcription factor 3; phospholipase A2; insulin responsive sequence DNA binding protein-1) stress response (e.g. heat shock 70kD protein 1A; heat shock protein 60; glutathione S-transferase Yc2 subunit), ion channels and receptors (e.g. ATPase, (Na+)/K+ transporting, beta 4 polypeptide; ATPase, H+/K+ transporting, nongastric, alpha polypeptide). Moreover some other genes with no definite functional clusters were also changed such as e.g. S100 calcium binding protein A3; ubiquitin carboxy-terminal hydrolase L1; interleukin 18. Gene ontology analysis revealed several significantly enriched functional inter-relationships between genes influenced by metabolic syndrome.

CONCLUSIONS

Metabolic syndrome significantly alters cardiac gene expression profile which may be involved in development of cardiac pathologies in the presence of metabolic syndrome.

Pharmacokinetic characterization of amrubicin cardiac safety in an ex vivo human myocardial strip model. II. Amrubicin shows metabolic advantages over doxorubicin and epirubicin

Anthracycline-related cardiotoxicity correlates with cardiac anthracycline accumulation and bioactivation to secondary alcohol metabolites or reactive oxygen species (ROS), such as superoxide anion (O₂·⁻) and hydrogen peroxide H₂O₂). We reported that in an ex vivo human myocardial strip model, 3 or 10 μM amrubicin [(7S,9S)-9-acetyl-9-amino-7-[(2-deoxy-β-D-erythro-pentopyranosyl)oxy]-7,8,9,10-tetrahydro-6,11-dihydroxy-5,12-napthacenedione hydrochloride] accumulated to a lower level compared with equimolar doxorubicin or epirubicin (J Pharmacol Exp Ther 341:464-473, 2012). We have characterized how amrubicin converted to ROS or secondary alcohol metabolite in comparison with doxorubicin (that formed both toxic species) or epirubicin (that lacked ROS formation and showed an impaired conversion to alcohol metabolite). Amrubicin and doxorubicin partitioned to mitochondria and caused similar elevations of H₂O₂, but the mechanisms of H₂O₂ formation were different. Amrubicin produced H₂O₂ by enzymatic reduction-oxidation of its quinone moiety, whereas doxorubicin acted by inducing mitochondrial uncoupling. Moreover, mitochondrial aconitase assays showed that 3 μM amrubicin caused an O₂·⁻-dependent reversible inactivation, whereas doxorubicin always caused an irreversible inactivation. Low concentrations of amrubicin therefore proved similar to epirubicin in sparing mitochondrial aconitase from irreversible inactivation. The soluble fraction of human myocardial strips converted doxorubicin and epirubicin to secondary alcohol metabolites that irreversibly inactivated cytoplasmic aconitase; in contrast, strips exposed to amrubicin failed to generate its secondary alcohol metabolite, amrubicinol, and only occasionally exhibited an irreversible inactivation of cytoplasmic aconitase. This was caused by competing pathways that favored formation and complete or near-to-complete elimination of 9-deaminoamrubicinol. These results characterize amrubicin metabolic advantages over doxorubicin and epirubicin, which may correlate with amrubicin cardiac safety in preclinical or clinical settings.

Mitochondria death/survival signaling pathways in cardiotoxicity induced by anthracyclines and anticancer-targeted therapies

Anthracyclines remain the cornerstone of treatment in many malignancies but these agents have a cumulative dose relationship with cardiotoxicity. Development of cardiomyopathy and congestive heart failure induced by anthracyclines are typically dose-dependent, irreversible, and cumulative. Although past studies of cardiotoxicity have focused on anthracyclines, more recently interest has turned to anticancer drugs that target many proteins kinases, such as tyrosine kinases. An attractive model to explain the mechanism of this cardiotoxicity could be myocyte loss through cell death pathways. Inhibition of mitochondrial transition permeability is a valuable tool to prevent doxorubicin-induced cardiotoxicity. In response to anthracycline treatment, activation of several protein kinases, neuregulin/ErbB2 signaling, and transcriptional factors modify mitochondrial functions that determine cell death or survival through the modulation of mitochondrial membrane permeability. Cellular response to anthracyclines is also modulated by a myriad of transcriptional factors that influence cell fate. Several novel targeted chemotherapeutic agents have been associated with a small but worrying risk of left ventricular dysfunction. Agents such as trastuzumab and tyrosine kinase inhibitors can lead to cardiotoxicity that is fundamentally different from that caused by anthracyclines, whereas biological effects converge to the mitochondria as a critical target.

Role of hypoxia-inducible factors in the dexrazoxane-mediated protection of cardiomyocytes from doxorubicin-induced toxicity

BACKGROUND AND PURPOSE

Iron aggravates the cardiotoxicity of doxorubicin, a widely used anticancer anthracycline, and the iron chelator dexrazoxane is the only agent protecting against doxorubicin cardiotoxicity; however, the mechanisms underlying the role of iron in doxorubicin-mediated cardiotoxicity and the protective role of dexrazoxane remain to be established. As iron is required for the degradation of hypoxia-inducible factors (HIF), which control the expression of antiapoptotic and protective genes, we tested the hypothesis that dexrazoxane-dependent HIF activation may mediate the cardioprotective effect of dexrazoxane.

EXPERIMENTAL APPROACH

Cell death, protein levels (by immunoblotting) and HIF-mediated transcription (using reporter constructs) were evaluated in the rat H9c2 cardiomyocyte cell line exposed to low doses of doxorubicin with or without dexrazoxane pretreatment. HIF levels were genetically manipulated by transfecting dominant-negative mutants or short hairpin RNA.

KEY RESULTS

Treatment with dexrazoxane induced HIF-1α and HIF-2α protein levels and transactivation capacity in H9c2 cells. It also prevented the induction of cell death and apoptosis by exposure of H9c2 cells to clinically relevant concentrations of doxorubicin. Suppression of HIF activity strongly reduced the protective effect of dexrazoxane. Conversely, HIF-1α overexpression protected against doxorubicin-mediated cell death and apoptosis also in cells not exposed to the chelator. Exposure to dexrazoxane increased the expression of the HIF-regulated, antiapoptotic proteins survivin, Mcl1 and haem oxygenase.

CONCLUSIONS AND IMPLICATIONS

Our results showing HIF-dependent prevention of doxorubicin toxicity in dexrazoxane-treated H9c2 cardiomyocytes suggest that HIF activation may be a mechanism contributing to the protective effect of dexrazoxane against anthracycline cardiotoxicity.

Relationship of drug metabolizing enzyme genotype to plasma levels as well as myelotoxicity of cyclophosphamide in breast cancer patients

PURPOSE

The cytotoxic drug cyclophosphamide (CP) is bioactivated into 4-hydroxy-cyclophosphamide (4-OH-CP) through cytochrome P450 enzymes and cleared through aldehyde dehydrogenase and glutathione S-transferase. This prospective study analyzes the influence of drug metabolizing enzyme genotype on (1) plasma 4-OH-CP:CP ratio and (2) myelotoxicity in breast cancer patients on 500 mg/m(2) cyclophosphamide.

METHODS

Sixty-eight female breast cancer patients on FAC (fluorouracil, adriamycin, cyclophosphamide) were included. Genotyping of cytochrome P450 enzymes CYP2B6, CYP2C9, CYP2C19, CYP3A5, aldehyde dehydrogenase (ALDH3A1), and glutathione S-transferase (GSTA1) was done either through RFLP or pyrosequencing. Plasma CP and 4-OH-CP were measured immediately and 1 and 2 h after the end of infusion through LC-MS. The leukocyte count was determined on day 10 and 20 after chemotherapy.

RESULTS

At CP dose of 500 mg/m(2), the 4-OH-CP:CP ratio was negatively affected by CYP2C19*2 genotype (p = 0.039) showing a gene-dose effect. Moreover ALDH3A1*2 genotype increased 4-OH-CP:CP ratio (p = 0.037). These effects did not remain significant in a univariate analysis of variance including all genotypes. GSTA1*B carriers were at increased risk of severe leucopenia (OR 6.94; 95% CI 1.75-27.6, p = 0.006).

CONCLUSION

The myelotoxicity in patients receiving FAC is related to the activity of the phase-II enzyme GSTA1 but is independent of the formation of 4-OH-CP.

Effect of hypothermia on doxorubicin-induced cardiac myoblast signaling and cell death

BACKGROUND

Anthracyclines (AC) are useful chemotherapeutic agents whose principal limitation is cardiac toxicity, which may progress to heart failure, transplantation or even death. We have shown that this toxicity involves oxidative stress-induced activation of the DNA damage pathway. Hypothermia has been shown to be protective against other diseases involving oxidative stress but has not been studied in models of AC toxicity.

METHODS

In the current experiments, H9C2 cardiac myoblasts were treated with varying concentrations of the AC doxorubicin (DOX) during normothermia (37°C) or mild hypothermia (35°C). Total cell death was assayed using trypan blue exclusion and apoptosis by terminal deoxynucleotidyl transferase-mediated deoxyuridine-biotin nick end labeling (TUNEL) staining. Oxidative stress was assayed using the fluorescent indicator 2'7'-dichlorofluorescein diacetate. DNA damage pathway activation was assayed by immunostaining for H2AX and p53. Mitochondrial membrane potential was assayed by JC-1 staining.

RESULTS

At all concentrations of DOX examined (1, 2.5 and 5 μM), hypothermia reduced oxidative stress, activation of H2AX and p53, loss of mitochondrial membrane potential and total and apoptotic cell death (P=.001-.03 for each observation).

CONCLUSIONS

The reduction of oxidative stress-induced activation of the DNA damage pathway and consequent cell death by mild hypothermia supports a possible protective role to reduce the clinical impact of DOX-induced cardiac toxicity. Such an approach may allow expanded use of these effective chemotherapeutic agents to increase cancer cure rates.

Protective effects of decursin and decursinol angelate against amyloid β-protein-induced oxidative stress in the PC12 cell line: the role of Nrf2 and antioxidant enzymes

The protective effects of decursin (D) and decursinol angelate (DA) purified from Angelica gigas Nakai on amyloid β-protein (Aβ)-induced neurotoxicity and the underlying mechanisms were investigated. Aβ plays a major role in the pathogenesis of Alzheimer's disease (AD) by eliciting oxidative stress. It significantly increased cytotoxicity and lipid peroxidation, but decreased glutathione contents and antioxidant enzyme activities. All of these results were markedly reversed by pretreatment with D or DA. Nuclear transcription factor Nrf2, which regulates the expression of antioxidant enzymes, was significantly increased by D or DA pretreatment. Furthermore, D and DA suppressed Aβ aggregation. These results suggest that D and DA increase cellular resistance to Aβ-induced oxidative injury in the rat pheochromocytoma (PC12) cells, presumably through not only the induction of Nrf2 and related antioxidant enzymes, but also the anti-aggregation of Aβ. Thus D and DA have therapeutic potential in treating AD and other oxidative stress-related diseases.

Activation of the aryl hydrocarbon receptor by doxorubicin mediates cytoprotective effects in the heart

AIMS

Doxorubicin (DOX) is a highly effective chemotherapeutic agent; however, cumulative dose-dependent cardiotoxicity is a significant side effect of this therapy. Because DOX is a polyaromatic hydrocarbon, we hypothesized that it will be metabolized by the activation of the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor that is involved in the metabolism of numerous xenobiotic agents. These studies were performed to determine whether DOX activates AhR and whether this activation modulates the toxicity of DOX in cardiomyocytes.

METHODS AND RESULTS

Treatment with DOX induced AhR migration to the nucleus, increased AhR binding with its co-factor, aryl hydrocarbon receptor nuclear translocator-1 (ARNT1), and increased the expression of AhR-regulated phase I (CYP1A1) and phase II (GSTA1) drug-metabolizing enzymes in both cardiomyocytes and in the intact heart. Knockdown of AhR in H9C2 cells abolished DOX-induced increases in CYP1A1 and GSTA1 expression. Similar results were obtained by treating adult rat ventricular myocytes with the AhR antagonist, CH-223191. Taken together, these findings indicate that DOX-induced upregulation of CYP1A1 and GSTA1 expression is AhR dependent. AhR null mice treated with 10 mg/kg DOX did not show any activation of CYP1A1 or GSTA1 expression. Moreover, lack of AhR in vivo resulted in a significant decrease in left ventricular function compared with wild-type animals, and increased p53 activation and apoptosis in the heart after treatment with DOX.

CONCLUSIONS

These findings indicate that AhR plays an important role in DOX metabolism by the heart and further demonstrate that AhR is cardioprotective against DOX-induced cardiotoxicity.

GSTT1, GSTM1, and GSTP1 polymorphisms and chemotherapy response in locally advanced breast cancer

The glutathione S-transferase (GST) family consists of phase II detoxification enzymes that catalyze the conjugation of toxic substances, such as chemotherapeutic agents, to glutathione. We examined whether GSTT1/GSTT1"null", GSTM1/GSTM1"null" and GSTP1Ile105Ile/GSTP1Ile105Val polymorphisms are associated with different response rates to neoadjuvant chemotherapy in the treatment of stage II and III breast cancer. Forty Brazilian women with invasive ductal adenocarcinoma of the breast submitted to neoadjuvant chemotherapy, using 5-fluorouracil, epirubicin and cyclophosphamide, were genotyped for the GSTT1, GSTM1 and GSTP1 genes. Clinical response was assessed by RECIST criteria. Comparisons were made for the three genes alone and in pairs, as polymorphic and as wild-type combinations and polymorphic/wild-type combinations. We analyzed all possible combinations and their response rate. Patients with the GSTT1/GSTP1105Ile combination were found to have a significantly better response than GSTT1"null"/GSTP1105Val (P = 0.0209) and GSTT1/GSTM1 (P = 0.0376) combinations. Analysis of all possible combinations showed the GSTM1"null" polymorphic genotype to be present in four, and the wild-type GSTP1105Ile in six of the combinations associated with the largest number of responding patients. We found that patients with the GSTT1/GSTP1105Ile wild-type combination had a significantly higher response rate to chemotherapy than patients with the respective polymorphic GSTT1"null"/GSTP1105Val combination or patients with the wild-type GSTT1/GSTM1. The six gene combinations associated with the largest number of responding patients were found to contain the wild-type GSTP1105Ile and the polymorphic-type GSTM1"null". These specific combinations were virtually absent in the combinations with few responding patients.

Epigallocatechin gallate protects H9c2 cardiomyoblasts against hydrogen dioxides- induced apoptosis and telomere attrition

Epigallocatechin gallate (EGCG), the major component of polyphenols in green tea, has recently attracted considerable attention for its cardioprotective effects. Telomere signalling plays a role in regulating cardiomyocyte apoptosis during cardiac dysfunction. The purpose of this study was to investigate the effects of EGCG on oxidative stress-induced apoptosis and telomere attrition in cardiomyocytes. H9c2 cells were incubated with EGCG, 50 and 100 mg/l, for 24 h. Apoptosis induced by 200 micromol/l hydrogen dioxide (H(2)O(2)) was analyzed by DAPI nuclear staining, electron microscopy, electrophoresis of DNA fragments and flow cytometry. When H9c2 cells were incubated with H(2)O(2) for 12-24 h, the intracellular and extracellular H(2)O(2) concentrations were not affected by the presence of EGCG. Chromatin condensation, DNA fragmentation and apoptotic body formation were observed in H(2)O(2)-induced injury. Flow cytometry analysis showed that the apoptotic rate increased remarkably. EGCG significantly inhibited H(2)O(2)-induced apoptotic morphological changes and apoptotic rate. When H9c2 cells were incubated with H(2)O(2), the telomere length shortened and the protein expression of telomere repeat-binding factor 2 (TRF(2)) decreased gradually, while the protein levels of p53 and p21 increased. EGCG significantly inhibited telomere attrition, TRF(2) loss and p53, p21 upregulation induced by H(2)O(2). These results suggested that EGCG might suppress oxidative stress-induced cardiomyocyte apoptosis through inhibiting telomere dependent apoptotic pathway.

Cardiac side-effects of cancer chemotherapy

The spectrum of cardiac side-effects of cancer chemotherapy has expanded with the development of combination, adjuvant and targeted chemotherapies. Their administration in multiple regimens has increased greatly, including in older patients and in patients with cardiovascular and/or coronary artery disease (CAD). Cardiac toxicity of anthracyclines involves oxidative stress and apoptosis. Early detection combines 2D-echocardiography and/or radionuclide angiography and recent methods such as tissue Doppler imaging, strain rate echocardiography and sampling of serial troponin and/or NT-proBNP levels. Dexrazoxane has proven effective in the prevention of dose-related toxicity in children and adults. High doses of the alkylating drugs cyclophosphamide and ifosfamide may result in a reversible heart failure and in life-threatening arrhythmias. Myocardial ischemia induced by the antimetabolites 5-fluorouracil and capecitabine impacts prognosis of patients with prior CAD. Severe arrhythmias may complicate administration of microtubule inhibitors. Targeted therapies with the antibody-based tyrosine kinases (TK) inhibitors trastuzumab and, to a lesser extent, alemtuzumab induce heart failure or asymptomatic LV dysfunction in 1-4% and 10%, respectively. Cetuximab and rituximab induce hypotension, whereas bevacizumab may promote severe hypertension and venous thromboembolism. Small molecule TK inhibitors may also elicit LV dysfunction, in only few patients treated with imatinib mesylate, but in a substantially higher proportion of those receiving the multitargeted TK inhibitor sunitinib or the recently approved drugs erlotinib, lapatinib and dasatinib. Management of patients at increased cardiovascular risk associated with advancing age, previous CAD or targeted therapies may be optimized by referral to a cardiologist in a cross-specialty teamwork.

Adverse effects of high glucose and free fatty acid on cardiomyocytes are mediated by connective tissue growth factor

Diabetic cardiomyopathy is characterized by interstitial fibrosis and cardiomyocyte hypertrophy and apoptosis. Also known as CCN2, connective tissue growth factor (CTGF) is implicated in the fibrosis; however, whether it contributes to cardiomyocytes changes and adverse effects of high glucose and lipids on these cells remains unknown. Hearts from streptozotocin-induced diabetic rats had elevated CTGF and changes of pathological myocardial hypertrophy, fibrosis, and cardiomyocyte apoptosis. Rat H9c2 cardiomyocytes were then treated with recombinant human (rh)CTGF, high glucose, or the saturated free fatty acid palmitate. Each reagent induced cell hypertrophy, as indicated by the ratio of total protein to cell number, cell size, and gene expression of cardiac hypertrophy marker genes atrial natriuretic peptide (ANP), and α-skeletal actin. Each treatment also caused apoptosis measured by increased caspase3/7 activity, apoptotic cells by transferase-mediated dUTP nick end labeling (TUNEL) assay, and lower viable cell number. Further studies showed CTGF mRNA was rapidly induced by high glucose and palmitate in H9c2 cells and in mouse neonatal cardiomyocyte primary cultures. small interfering RNA against CTGF blocked the high glucose and palmitate induction of hypertrophy and apoptosis. In addition, these CTGF effects were through the tyrosine kinase A (TrkA) receptor with tyrosine kinase activity, which has previously been implicated in CTGF signaling: TrkA was phosphorylated by CTGF, and a specific TrkA blocker abrogated CTGF-induced effects on hypertrophy and apoptosis. For the first time in any system, fatty acid is newly identified as a regulator of CTGF, and this work implicates autocrine CTGF as a mediator of adverse effects of high glucose and fatty acids in cardiomyocytes.

N-acetylcysteine amide decreases oxidative stress but not cell death induced by doxorubicin in H9c2 cardiomyocytes

Background

While doxorubicin (DOX) is widely used in cancer chemotherapy, long-term severe cardiotoxicity limits its use. This is the first report of the chemoprotective efficacy of a relatively new thiol antioxidant, N-acetylcysteine amide (NACA), on DOX-induced cell death in cardiomyocytes. We hypothesized that NACA would protect H9c2 cardiomyocytes from DOX-induced toxicity by reducing oxidative stress. Accordingly, we determined the ability of NACA to mitigate the cytotoxicity of DOX in H9c2 cells and correlated these effects with the production of indicators of oxidative stress.

Results

DOX at 5 μM induced cardiotoxicity while 1) increasing the generation of reactive oxygen species (ROS), 2) decreasing levels and activities of antioxidants and antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase) and 3) increasing lipid peroxidation. NACA at 750 μM substantially reduced the levels of ROS and lipid peroxidation, as well as increased both GSH level and GSH/GSSG ratio. However, treating H9c2 cells with NACA did little to protect H9c2 cells from DOX-induced cell death.

Conclusion

Although NACA effectively reduced oxidative stress in DOX-treated H9c2 cells, it had minimal effects on DOX-induced cell death. NACA prevented oxidative stress by elevation of GSH and CYS, reduction of ROS and lipid peroxidation, and restoration of antioxidant enzyme activities. Further studies to identify oxidative stress-independent pathways that lead to DOX-induced cell death in H9c2 are warranted.

N-acetylcysteine amide decreases oxidative stress but not cell death induced by doxorubicin in H9c2 cardiomyocytes

BACKGROUND

While doxorubicin (DOX) is widely used in cancer chemotherapy, long-term severe cardiotoxicity limits its use. This is the first report of the chemoprotective efficacy of a relatively new thiol antioxidant, N-acetylcysteine amide (NACA), on DOX-induced cell death in cardiomyocytes. We hypothesized that NACA would protect H9c2 cardiomyocytes from DOX-induced toxicity by reducing oxidative stress. Accordingly, we determined the ability of NACA to mitigate the cytotoxicity of DOX in H9c2 cells and correlated these effects with the production of indicators of oxidative stress.

RESULTS

DOX at 5 microM induced cardiotoxicity while 1) increasing the generation of reactive oxygen species (ROS), 2) decreasing levels and activities of antioxidants and antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase) and 3) increasing lipid peroxidation. NACA at 750 microM substantially reduced the levels of ROS and lipid peroxidation, as well as increased both GSH level and GSH/GSSG ratio. However, treating H9c2 cells with NACA did little to protect H9c2 cells from DOX-induced cell death.

CONCLUSION

Although NACA effectively reduced oxidative stress in DOX-treated H9c2 cells, it had minimal effects on DOX-induced cell death. NACA prevented oxidative stress by elevation of GSH and CYS, reduction of ROS and lipid peroxidation, and restoration of antioxidant enzyme activities. Further studies to identify oxidative stress-independent pathways that lead to DOX-induced cell death in H9c2 are warranted.

Oxidative modulation of marcaine and lekoptin in H9C2 rat myoblasts

AIM

The cytotoxicity of marcaine was estimated in combination with a calcium channel blocker. In addition, the influence of marcaine and marcaine plus lekoptin on a model system using the H9C2 cardiac cell line was investigated.

METHODS

Cells were incubated for five hours with marcaine, lekoptin, or with both drugs simultaneously. Apoptotic cells were detected using the TUNEL assay and the alkaline comet assay. Mitochondrial cell function after drug uptake was examined using the MTT assay. The concentration of MDA (malondialdehyde) -- the final product of fatty-acid peroxidation, was quantified spectrophotometrically. The expression of glutathione S-transferase pi (GST-pi) was detected by immunofluorescence (IF) and Western blotting (WB) and inducible nitric oxide synthase (iNOS) was assessed by immunocytochemical staining (ABC).

RESULTS

Incubation with marcaine resulted in the highest number of apoptotic cells. After incubation with both marcaine and lekoptin, moderate damage to cells (54.2%+/-1.775% of DNA destruction) was observed. The highest levels of iNOS and GST-pi expression were observed in cells treated with marcaine and marcaine plus lekoptin. The characteristic nuclear GST-pi expression was observed in cells treated with both drugs.

CONCLUSION

Lekoptin stimulated cells to proliferate. Marcaine caused membrane damage and ultimately cell death.

Hexane/ethanol extract of Glycyrrhiza uralensis licorice suppresses doxorubicin-induced apoptosis in H9c2 rat cardiac myoblasts

Doxorubicin (DOX) is an anthracycline antibiotic, and has been recognized as one of the most effective anti-neoplastic agents in cancer chemotherapy. However, its usefulness is limited by its profound cardiotoxicity. Licorice is one of the most frequently prescribed agents in traditional herbal medicine, and is also employed as a natural sweetening additive. In traditional Chinese medicine, licorice root is added to a variety of herbal preparations to detoxify the effects of the other herbs in the preparation. In the present study, we explored the possibility that Glycyrrhiza uralensis licorice may alleviate DOX-induced cardiotoxicity. The hexane/ethanol extract of Glycyrrhiza uralensis (HEGU), which lacks glycyrrhizin, was prepared because glycyrrhizin intake has previously been reported to induce hypertension. In an effort to determine whether HEGU ameliorates DOX-induced cytotoxicity in H9c2 rat cardiac myoblasts, the cells were pretreated with 0-15 mg/L HEGU, then treated with doxorubicin. The pretreatment of cells with HEGU resulted in a significant mitigation of DOX-induced reductions in cell numbers (34 +/- 7%) and increases in apoptosis (53 +/- 1%). The Western blot analysis of cell lysates showed that HEGU suppressed DOX-induced increases in the levels of p53, phospho-p53 (Ser 15), and Bax. In addition, HEGU induced an increase in the levels of Bcl-xL, regardless of DOX-treatment. HEGU inhibited the DOX-induced cleavage of caspases 9, 3, and 7, as well as DOX-induced poly(ADP-ribose) polymerase cleavage. Furthermore, HEGU caused reductions in the viable cell numbers of HT-29 human colon cancer cells (IC50 = 10.7 +/- 0.3 mg/L), MDA-MB-231 human breast cancer cells (IC50 = 7.5 +/- 0.1 mg/L), and DU145 human prostate cancer cells (IC50 = 4.7 +/- 0.5 mg/L). HEGU augmented DOX-induced reductions in the viability of DU145 cells (15 +/- 1%). These results indicate that HEGU may potentially be an effective agent for the alleviation of DOX-induced cardiotoxicity.

Reactive oxygen species-independent apoptosis in doxorubicin-treated H9c2 cardiomyocytes: role for heme oxygenase-1 down-modulation

Increased oxidative stress and apoptosis have been implicated in the cardiotoxicity that limits the clinical use of doxorubicin (DOX) as an anti-tumoral drug, but the mechanism of DOX-mediated apoptosis remains unclear. We examined the interplay between oxidative stress and cell death in cardiac-derived H9c2 myocytes exposed to DOX doses in the range of the plasma levels found in patients undergoing chemotherapy. A low DOX concentration (0.25 microM) induced apoptosis, whereas the cells treated with the high dose of 2 microM also showed necrosis. The production of reactive oxygen species (ROS) and induction of oxidative stress markers was increased in the cells treated with 2 microM DOX but not in those treated with the low dose. Surprisingly, heme oxygenase (HO-1) expression was down-modulated in the cells exposed to 0.25 microM DOX, and its Bach 1 transcriptional repressor was induced. In line with the role of HO-1 as an anti-apoptotic protein, inhibiting HO-1 activity with SnPPIX was sufficient to induce apoptosis and increased DOX-mediated apoptosis, whereas hemin-induced HO-1 activation prevented DOX-mediated apoptotic cell death. In brief, our findings do not support the hypothesis that oxidative stress plays a role in the apoptotic cell death occurring in cardiomyocytes exposed to low concentrations of DOX, but suggest that DOX may facilitate the apoptosis of cardiomyocytes by inhibiting the anti-apoptotic HO-1.

Differential protein expression during aging in ventricular myocardium of Fischer 344 x Brown Norway hybrid rats

The aging heart undergoes well characterized structural changes associated with functional decline, though the underlying mechanisms are not understood. The aim of this study was to determine to what extent ventricular myocardial protein expression was altered with age and which proteins underwent protein nitration. Fischer 344 x Brown Norway F1 hybrid (FBN) rats of four age groups were used, 4, 12, 24, and 34 months. Differential protein expression was determined by 2-DE and proteins were identified by peptide mass fingerprinting. Altered protein nitration with age was assessed by immunoblotting. Over 1000 protein spots per sample were detected, and 255 were found to be differentially expressed when all aged groups were compared to young rats (4 months) (p0.05). A strong positive correlation between differential protein expression and increasing age (p=0.03, R(2)=0.997) indicated a progressive, rather than abrupt, change with age. Of 46 differentially expressed proteins identified, seventeen have roles in apoptosis, ten in hypertrophy, seven in fibrosis, and three in diastolic dysfunction, aging-associated processes previously reported in both human and FBN rat heart. Protein expression alterations detected here could have beneficial effects on cardiac function; thus, our data indicate a largely adaptive change in protein expression during aging. In contrast, differential protein nitration increased abruptly, rather than progressively, at 24 months of age. Altogether, the results suggest that differential myocardial protein expression occurs in a progressive manner during aging, and that a proteomic-based approach is an effective method for the identification of potential therapeutic targets to mitigate aging-related myocardial dysfunction.

HSP27 regulates p53 transcriptional activity in doxorubicin-treated fibroblasts and cardiac H9c2 cells: p21 upregulation and G2/M phase cell cycle arrest

Treatment of cancer patients with anthracyclin-based chemotherapeutic drugs induces congestive heart failure by a mechanism involving p53. However, it is not known how p53 aggravates doxorubicin (Dox)-induced toxicity in the heart. On the basis of in vitro acute toxicity assay using heat shock factor-1 (HSF-1) wild-type (HSF-1(+/+)) and HSF-1-knockout (HSF-1(-/-)) mouse embryonic fibroblasts and neonatal rat cardiomyocyte-derived H9c2 cells, we demonstrate a novel mechanism whereby heat shock protein 27 (HSP27) regulates transcriptional activity of p53 in Dox-treated cells. Inhibition of p53 by pifithrin-alpha (PFT-alpha) provided different levels of protection from Dox that correlate with HSP27 levels in these cells. In HSF-1(+/+) cells, PFT-alpha attenuated Dox-induced toxicity. However, in HSF-1(-/-) cells (which express a very low level of HSP27 compared with HSF-1(+/+) cells), there was no such attenuation, indicating an important role of HSP27 in p53-dependent cell death. On the other hand, immunoprecipitation of p53 was found to coimmunoprecipitate HSP27 and vice versa (confirmed by Western blotting and matrix-assisted laser desorption/ionization time of flight), demonstrating HSP27 binding to p53 in Dox-treated cells. Moreover, upregulation of p21 was observed in HSF-1(+/+) and H9c2 cells, indicating that HSP27 binding transactivates p53 and enhances transcription of p21 in response to Dox treatment. Further analysis with flow cytometry showed that increased expression of p21 results in G(2)/M phase cell cycle arrest in Dox-treated cells. Overall, HSP27 binding to p53 attenuated the cellular toxicity by upregulating p21 and prevented cell death.

Tanshinone IIA protects neonatal rat cardiomyocytes from adriamycin-induced apoptosis

Tanshinone IIA (TSN) is a monomer extracted from the Chinese herb Danshen. In this study, we examined the effect of Tanshinone IIA on adriamycin (ADR)-induced apoptosis in neonatal rat cardiomyocytes and underlying molecular mechanisms. Primary cultured cardiomyocytes were treated with 1 micromol/L of adriamycin for 24 h with or without pretreatment with Tanshinone IIA (0.5-2 micromol/L) for 2 h. 3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Hoechst staining, and flow cytometry measurement were used to assess cell viability and apoptosis. Fluorescent probes 2',7'-dichlorofluorescein diacetate and dihydroethidium were used to detect the production of reactive oxygen species. Western blotting was used to evaluate the expression of Bcl-2 and Bax proteins. Adriamycin significantly induced apoptosis in cardiomyocytes. Tanshinone IIA (0.5-2 micromol/L) ameliorated apoptosis induced by adriamycin in a dose-dependent manner. Tanshinone IIA (2 micromol/L) markedly attenuated adriamycin-induced reactive oxygen species production. Western blotting revealed that Tanshinone IIA prevented the adriamycin-mediated reduction of the ratio of Bcl-2/Bax. In conclusion, Tanshinone IIA significantly inhibits adriamycin-induced cardiomyocyte apoptosis in a dose-dependent manner, and this effect is at least partly caused by its antioxidant properties.

Induction of glutathione transferase in insulin-like growth factor type I receptor-overexpressed hepatoma cells

Insulin-like growth factor type I receptor (IGF-IR) is frequently overexpressed in human hepatocellular carcinoma cells (HCC), and this overexpression has been correlated with increased tumor growth. The protective response of HCC to reactive oxygen species (ROS) produced by chemotherapeutic agents is mediated with the induction of phase II detoxifying genes including glutathione transferase (GST). To understand the roles of IGF-IR overexpression in HCC in terms of its detoxifying effect on ROS and conferred resistance to chemotherapy, we analyzed whether IGF-IR overexpressions affect IGF-1-inducible GST expression. GSTalpha was induced by exposure to IGF-1 in IGF-IR cells but not in cells expressing normal levels of IGF-IR. Furthermore, IGF-IR-overexpressed HCCs (IR-HCC) are more resistant to doxorubicin than control HCC cells, which was associated with the increased GST induction by IGF-1. Molecular analyses using GSTA2 promoter supported the involvement of xenobiotic response element (XRE) in GSTalpha induction. IGF-1 caused the nuclear translocation of CCAAT/enhancer-binding protein beta (C/EBPbeta), which might be responsible for XRE activation. In addition, IGF-1 increased the activities of phosphatidylinositol 3-kinase (PI3-kinase) and extracellular signal-regulated kinase in IR-HCCs. Moreover, the inhibition of PI3-kinase completely abolished the nuclear translocation of C/EBPbeta and the up-regulation of GSTalpha protein in IR-HCC treated with IGF-1. However, specific inhibitors against extracellular signal-regulated kinase, c-Jun N-terminal kinase, or p38 kinase did not alter IGF-1-inducible GSTalpha expression. These results provide evidence that one of the pathological consequences of IGF-IR overexpression in HCCs is the potentiation of GSTalpha inducibility by IGF-1. Moreover, this potentiation of GST may be associated with decreased susceptibility to chemotherapeutic agents such as doxorubicin.

Doxorubicin-induced cardiotoxicity: direct correlation of cardiac fibroblast and H9c2 cell survival and aconitase activity with heat shock protein 27

The use of doxorubicin (Dox) and its derivatives as chemotherapeutic drugs to treat patients with cancer causes dilated cardiomyopathy and congestive heart failure due to Dox-induced cardiotoxicity. In this work, using heat shock factor-1 wild-type (HSF-1(+/+)) and HSF-1 knockout (HSF-1(-/-)) mouse fibroblasts and embryonic rat heart-derived cardiac H9c2 cells, we show that the magnitude of protection from Dox-induced toxicity directly correlates with the level of the heat shock protein 27 (HSP27). Western blot analysis of normal and heat-shocked cells showed the maximum expression of HSP27 in heat-shocked cardiac H9c2 cells and no HSP27 in HSF-1(-/-) cells (normal or heat-shocked). Correspondingly, the cell viability, measured [with (3,4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay] after treatment with various concentrations of Dox, was the highest in heat-shocked H9c2 cells and the lowest in HSF-1(-/-) cells. Depleting HSP27 in cardiac H9c2 cells by small interfering (si)RNA also reduced the viability against Dox, confirming that HSP27 does protect cardiac cells against the Dox-induced toxicity. The cells that have lower HSP27 levels such as HSF-1(-/-), were found to be more susceptible for aconitase inactivation. Based on these results we propose a novel mechanism that HSP27 plays an important role in protecting aconitase from Dox-generated O(2)*(-), by increasing SOD activity. Such a protection of aconitase by HSP27 eliminates the catalytic recycling of aconitase released Fe(II) and its deleterious effects in cardiac cells.

Change in TNF-alpha receptor expression is a relevant event in doxorubicin-induced H9c2 cardiomyocyte cell death

Doxorubicin (Doxo) is a widely used anticancer drug given for the treatment of leukemias, lymphomas, and solid tumors. Despite its potent antitumor effects, the cardiotoxicity of this drug limits its clinical use. The biochemical mechanisms of Doxo-induced cardiotoxicity remain unclear. Doxo has been shown to induce apoptosis in cardiomyocytes that seems to be responsible, at least in part, for Doxo cardiotoxicity. In this study, we investigated tumor necrosis factor-alpha (TNF-alpha) receptor-mediated signaling to better understand the causes of Doxo-induced cardiotoxicity. Here, we report that Doxo is a potent inducer of apoptosis in both H9c2 cardiomyocytes and U2OS osteosarcoma tumor cells, with significant differences in terms of kinetics and caspase activation between the two cell lines. Interestingly, Doxo-induced apoptosis is accompanied by relevant changes in TNF-alpha receptor levels in H9c2 cardiomyocytes but not in U2OS cells. Moreover, treatment with exogenous TNF-alpha strongly potentiates the apoptotic effect of Doxo in H9c2 cardiomyocytes but not in U2OS cells. Our findings show that the function of TNF receptors I and II is affected by Doxo to ultimately modulate apoptosis and cell survival in H9c2 cardiomyocytes, reinforcing the recent evidence of the relevant role of TNF-alpha receptor-mediated signaling in cardiotoxicity induced by anthracyclines.

Proteomic approach to study the effects of various oxidatively modified low-density lipoprotein on regulation of protein expression in human umbilical vein endothelial cell

Circulating low-density lipoprotein (LDL) isolated by our laboratory, a new form of modified LDL and designated as L5, has been reported to be cytotoxic by inducing apoptosis of vascular endothelial cells in vitro. The objective of this study was to compare the biological functions of three different forms of oxidatively modified LDL on human umbilical vein endothelial cells (HUVEC) by proteomic approaches. HUVEC were incubated with serum-free medium, native LDL (N-LDL), L5 isolated from familial hypercholesterolemic subjects (FH-L5), copper-oxidized LDL (Cu-ox-LDL), and atheroma-derived LDL (a-LDL) at 37 degrees C for 24 h. We found that HUVEC incubated with FH-L5 expressed approximately 3 fold higher concentration of MCP-1 than did cells subject to other treatments. All modified LDL significantly suppressed ATP synthase, Grp58, Grp78, and Prdx3. However, the expression of hnRNP C1/C2 was significantly enhanced by FH-L5 and a-LDL; glutathione transferase was significantly enhanced only by FH-L5. A concordant pattern of protein expression was observed between immunoblotting and 2D electrophoresis. Different forms of oxidatively modified LDL regulated HUVEC protein expression in different patterns, suggesting different roles for different oxLDL forms in inducing atherogenesis.

Genotyping the risk of anthracycline-induced cardiotoxicity

Anthracyclines belong to the most successful antineoplastic drugs, but they are cardiotoxic, which may result in congestive heart failure (CHF). The CHF risk increases with the cumulative anthracycline dose, but it seems also to be modified by individual factors. A role of the individual genetic background is consistent with the altered sensitivity to anthracyclines observed in many transgenic and knockout mouse strains. First clinical data obtained in humans suggest the existence of predisposing variants in genes involved in the oxidative stress, and in the metabolism and transport of anthracyclines. These data will have to be verified in further clinical trials before any attempts of their application in the individual cardiotoxicity prediction can be undertaken. In the meantime, anthracycline-induced cardiotoxicity can be best reduced by application of liposomal anthracycline formulations or by a co-medication with the cardioprotective iron chelator dexrazoxane.

Heat shock protects cardiac cells from doxorubicin-induced toxicity by activating p38 MAPK and phosphorylation of small heat shock protein 27

Doxorubicin (DOX) and its derivatives are used as chemotherapeutic drugs to treat cancer patients. However, production of DOX-mediated reactive oxygen species (ROS) by prolonged use of these drugs has been found to cause dilative cardiomyopathy and congestive heart failure. Thus various preventive modalities have been developed to avoid this side effect. We have found that the DOX-mediated oxidant-induced toxicity in cardiac cells could be minimized by hyperthermia-induced small heat shock protein 27 (HSP27); that is, this protein acts as an endogenous antioxidant against DOX-derived oxidants such as H(2)O(2). Heat shock-induced HSP27 was found to act as an antiapoptotic protein (reducing ROS and Bax-to-Bcl2 ratio) against DOX, and its phosphorylated isoforms stabilized F-actin remodeling in DOX-treated cardiac cells and, hence, attenuated the toxicity. Protein kinase assays and proteomic analyses suggested that higher expression of HSP27 and its phosphorylation are responsible for the protection in heat-shocked cells. Two-dimensional gel electrophoresis showed six isoforms (nonphosphorylated and phosphorylated) of HSP27. Matrix-assisted laser desorption/ionization time of flight analyses showed alpha- and beta-isoforms of HSP27, which are phosphorylated by various protein kinases. Ser(15) and Ser(85) phosphorylation of HSP27 by MAPK-assisted protein kinase 2 was found to be the key mechanism in reduction of apoptosis and facilitation of F-actin remodeling. The present study illustrates that hyperthermia protects cells from DOX-induced death through induction and phosphorylation of HSP27 and its antiapoptotic and actin-remodeling activities.

The role of aryl hydrocarbon receptor in the pathogenesis of cardiovascular diseases

Numerous experimental and epidemiological studies have demonstrated that polycyclic aromatic hydrocarbons (PAHs), which are major constituents of cigarette tobacco tar, are strongly involved in the pathogenesis of the cardiovascular diseases (CVDs). Knowing that PAH-induced toxicities are mediated by the activation of a cytosolic receptor, aryl hydrocarbon receptor (AhR), which regulates the expression of a group of xenobiotic metabolizing enzymes (XMEs) such as CYP1A1, CYP1A2, CYP1B1, NQO1, and GSTA1, suggests a direct link between AhR-regulated XMEs and CVDs. Therefore, identifying the localization and expression of the AhR and its regulated XMEs in the cardiovascular system (CVS) is of major importance in understanding their physiological and pathological roles. Generally, it was believed that the levels of AhR-regulated XMEs are lower in the CVS than in the liver; however, it has been shown that similar or even higher levels of expression are demonstrated in the CVS in a tissue- and species-specific manner. Moreover, most, if not all, AhR-regulated XMEs are differentially expressed in most of the CVS, particularly in the endothelium cells, aorta, coronary arteries, and ventricles. Although the exact mechanisms of PAH-mediated cardiotoxicity are not fully understood, several mechanisms are proposed. Generally, induction of CYP1A1, CYP1A2, and CYP1B1 is considered cardiotoxic through generating reactive oxygen species (ROS), DNA adducts, and endogenous arachidonic acid metabolites. However the cardioprotective properties of NQO1 and GSTA1 are mainly attributed to the antioxidant effect by decreasing ROS and increasing the levels of endogenous antioxidants. This review provides a clear understanding of the role of AhR and its regulated XMEs in the pathogenesis of CVDs, in which imbalance in the expression of cardioprotective and cardiotoxic XMEs is the main determinant of PAH-mediated cardiotoxicity.

DNA damage is an early event in doxorubicin-induced cardiac myocyte death

Anthracyclines are antitumor agents the main clinical limitation of which is cardiac toxicity. The mechanism of this cardiotoxicity is thought to be related to generation of oxidative stress, causing lethal injury to cardiac myocytes. Although protein and lipid oxidation have been documented in anthracycline-treated cardiac myocytes, DNA damage has not been directly demonstrated. This study was undertaken to determine whether anthracyclines induce cardiac myocyte DNA damage and whether this damage is linked to a signaling pathway culminating in cell death. H9c2 cardiac myocytes were treated with the anthracycline doxorubicin at clinically relevant concentrations, and DNA damage was assessed using the alkaline comet assay. Doxorubicin induced DNA damage, as shown by a significant increase in the mean tail moment above control, an effect ameliorated by inclusion of a free radical scavenger. Repair of DNA damage was incomplete after doxorubicin treatment in contrast to the complete repair observed in H2O2-treated myocytes after removal of the agent. Immunoblot analysis revealed that p53 activation occurred subsequent in time to DNA damage. By a fluorescent assay, doxorubicin induced loss of mitochondrial membrane potential after p53 activation. Chemical inhibition of p53 prevented doxorubicin-induced cell death and loss of mitochondrial membrane potential without preventing DNA damage, indicating that DNA damage was proximal in the events leading from doxorubicin treatment to cardiac myocyte death. Specific doxorubicin-induced DNA lesions included oxidized pyrimidines and 8-hydroxyguanine. DNA damage therefore appears to play an important early role in anthracycline-induced lethal cardiac myocyte injury through a pathway involving p53 and the mitochondria.

Multiple actions of pifithrin-alpha on doxorubicin-induced apoptosis in rat myoblastic H9c2 cells

Doxorubicin (Dox) is a chemotherapeutic agent that causes significant cardiotoxicity. We showed previously that Dox activates p53 and induces apoptosis in mouse hearts. This study was designed to elucidate the molecular events that lead to p53 stabilization, to examine the pathways involved in Dox-induced apoptosis, and to evaluate the effectiveness of pifithrin-alpha (PFT-alpha), a p53 inhibitor, in blocking apoptosis of rat H9c2 myoblasts. H9c2 cells that were exposed to 5 muM Dox had elevated levels of p53 and phosphorylated p53 at Ser15. Dox also triggered a transient activation of p38, p42/p44ERK, and p46/p54JNK MAP kinases. Caspase activity assays and Western blot analysis showed that H9c2 cells treated with Dox for 16 h had marked increase in the levels of caspases-2, -3, -8, -9, -12, Fas, and cleaved poly(ADP ribose) polymerase (PARP). There was a concomitant increase in p53 binding activity, cytochrome c release, and apoptosis. These results suggest that Dox can trigger intrinsic, extrinsic, and endoplasmic reticulum-associated apoptotic pathways. Pretreatment of cells with PFT-alpha followed by Dox administration attenuated Dox-induced increases in p53 levels and p53 binding activity and partially blocked the activation of p46/p54JNK and p42/p44ERK. PFT-alpha also led to decreased levels of caspases-2, -3, -8, -9, -12, Fas, PARP, cytochrome c release, and apoptosis. Our results suggest that p53 stabilization is a focal point of Dox-induced apoptosis and that PFT-alpha interferes with multiple steps of Dox-induced apoptosis.

Heat shock-induced attenuation of hydroxyl radical generation and mitochondrial aconitase activity in cardiac H9c2 cells

A mild heat shock (hyperthermia) protects cells from apoptotic and necrotic deaths by inducing overexpression of various heat shock proteins (Hsps). These proteins, in combination with the activation of the nitric oxide synthase (NOS) enzyme, play important roles in the protection of the myocardium against a variety of diseases. In the present work we report that the generation of potent reactive oxygen species (ROS), namely ·OH in cardiac H9c2 cells, is attenuated by heat shock treatment (2 h at 42°C). Western blot analyses showed that heat shock treatment induced overexpression of Hsp70, Hsp60, and Hsp25. The observed ·OH was found to be derived from the superoxide (O2−·) generated by the mitochondria. Whereas the manganese superoxide dismutase (MnSOD) activity was increased in the heat-shocked cells, the mitochondrial aconitase activity was reduced. The mechanism of O2−· conversion into ·OH in mitochondria is proposed as follows. The O2−· leaked from the electron transport chain, oxidatively damages the mitochondrial aconitase, releasing a free Fe2+. The aconitase-released Fe2+combines with H2O2to generate ·OH via a Fenton reaction and the oxidized Fe3+recombines with the inactivated enzyme after being reduced to Fe2+by other cellular reductants, turning it over to be active. However, in heat-shocked cells, because of higher MnSOD activity, the excess H2O2causes irreversible damage to the mitochondrial aconitase enzyme, thus inhibiting its activity. In conclusion, we propose that attenuation of ·OH generation after heat shock treatment might play an important role in reducing the myocardial ischemic injury, observed in heat shock-treated animals.

C-Phycocyanin Ameliorates Doxorubicin-Induced Oxidative Stress and Apoptosis in Adult Rat Cardiomyocytes

Doxorubicin (DOX), a potent antineoplastic agent, poses limitations for its therapeutic use due to the associated risk of developing cardiomyopathy and congestive heart failure. The cardiotoxicity of doxorubicin is associated with oxidative stress and apoptosis. We have recently shown that Spirulina, a blue-green alga with potent antioxidant properties, offered significant protection against doxorubicin-induced cardiotoxicity in mice. The aim of the present study was to establish the possible protective role of C-phycocyanin, one of the active ingredients of Spirulina, against doxorubicin-induced oxidative stress and apoptosis. The study was carried out using cardiomyocytes isolated from adult rat hearts. Doxorubicin significantly enhanced the formation of reactive oxygen species (ROS) in cells as measured by the 2',7'-dichlorodihydrofluorescein diacetate and dihydroethidium fluorescence. The doxorubicin-induced reactive oxygen species formation was significantly attenuated in cells pretreated with C-phycocyanin. It was further observed that the doxorubicin-induced DNA fragmentation and apoptosis, as assayed by TUNEL assay and flow cytometry coupled with BrdU-FITC/propidium iodide staining, were markedly attenuated by C-phycocyanin. C-phycocyanin also significantly attenuated the doxorubicin-induced increase in the expression of Bax protein, release of cytochrome c, and increase in the activity of caspase-3 in cells. In summary, C-phycocyanin ameliorated doxorubicin-induced oxidative stress and apoptosis in cardiomyocytes. This study further supports the crucial role of the antioxidant nature of C-phycocyanin in its cardioprotection against doxorubicin-induced oxidative stress and apoptosis.