Adriamycin-induced heart failure: mechanism and modulation

Long-acting phosphodiesterase-5 inhibitor tadalafil attenuates doxorubicin-induced cardiomyopathy without interfering with chemotherapeutic effect

Doxorubicin (DOX) is one of the most effective anticancer drugs. However, its cardiotoxicity remains a clinical concern that severely restricts its therapeutic usage. We designed this study to investigate whether tadalafil, a long-acting phosphodiesterase-5 (PDE-5) inhibitor, protects against DOX-induced cardiotoxicity. We also sought to delineate the cellular and molecular mechanisms underlying tadalafil-induced cardioprotection. Male CF-1 outbred mice were randomized into three groups (n = 15-24/group) to receive either saline (0.2 ml i.p.), DOX (15 mg/kg, given by a single intraperitoneal injection), or tadalafil (4 mg/kg p.o. daily for 9 days) plus DOX. Left ventricular function was subsequently assessed by transthoracic echocardiography and Millar conductance catheter. Cardiac contractile function was impaired by DOX, and it was significantly improved by cotreatment with tadalafil. Tadalafil attenuated DOX-induced apoptosis and depletion of prosurvival proteins, including Bcl-2 and GATA-4, in myocardium. Cardiac oxidative stress was attenuated and antioxidant capacity was enhanced by tadalafil possibly via up-regulation of mitochondrial superoxide dismutase (MnSOD). Moreover, the tadalafil-treated group demonstrated increased cardiac cGMP level and protein kinase G (PKG) activity. Tadalafil did not interfere with the efficacy of DOX in killing human osteosarcoma cells in vitro or its antitumor effect in vivo in tumor xenograft model. We conclude that tadalafil improved left ventricular function and prevented cardiomyocyte apoptosis in DOX-induced cardiomyopathy through mechanisms involving up-regulation of cGMP, PKG activity, and MnSOD level without interfering with the chemotherapeutic benefits of DOX.

ZAK is required for doxorubicin, a novel ribotoxic stressor, to induce SAPK activation and apoptosis in HaCaT cells

Doxorubicin is an anthracycline drug that is one of the most effective and widely used anticancer agents for the treatment of both hematologic and solid tumors. The stress-activated protein kinases (SAPKs) are frequently activated by a number of cancer chemotherapeutics. When phosphorylated, the SAPKs initiate a cascade that leads to the production of proinflammatory cytokines. Some inhibitors of protein synthesis, known as ribotoxic stressors, coordinately activate SAPKs and lead to apoptotic cell death. We demonstrate that doxorubicin effectively inhibits protein synthesis, activates SAPKs, and causes apoptosis. Ribotoxic stressors share a common mechanism in that they require ZAK, an upstream MAP3K, to activate the pro-apoptotic and proinflammatory signaling pathways that lie downstream of SAPKs. By employing siRNA mediated knockdown of ZAK or administration of sorafenib and nilotinib, kinase inhibitors that have a high affinity for ZAK, we provide evidence that ZAK is required for doxorubicin-induced proinflammatory and apoptotic responses in HaCaT cells, a pseudo-normal keratinocyte cell line, but not in HeLa cells, a cancerous cell line. ZAK has two different isoforms, ZAK-α (91 kDa) and ZAK-β (51 kDa). HaCaT or HeLa cells treated with doxorubicin and immunoblotted for ZAK displayed a progressive decrease in the ZAK-α band and the appearance of ZAK-β bands of larger size. Abrogation of these changes after exposure of cells to sorafenib and nilotinib suggests that these alterations occur following stimulation of ZAK. We suggest that ZAK inhibitors such as sorafenib or nilotinib may be effective when combined with doxorubicin to treat cancer patients.

Enhanced toxicity and ROS generation by doxorubicin in primary cultures of cardiomyocytes from neonatal metallothionein-I/II null mice

The clinical use of doxorubicin (Dox), a potent anticancer drug, is limited by its concurrent dose-dependent cardiotoxicity. We previously found that metallothionein-I/II (MT-I/II) null mice are more vulnerable to Dox-induced cardiomyopathy, but it is unknown whether depletion of MT would sensitize cardiomyocytes to Dox toxicity in vitro since the protective effect of MT still remains controversial. In the present study, a primary culture system of cardiomyocytes from neonatal MT-I/II null (MT(-/-)) and corresponding wild type (MT(+/+)) mice was established to unequivocally determine the effect of MT deficiency on Dox-induced toxicity. MT concentrations in the MT(-/-) cardiomyocytes were about 2.5-fold lower than those in MT(+/+) cardiomyocytes. MT(-/-) cardiomyocytes were more sensitive to Dox-induced cytotoxicity than MT(+/+) cardiomyocytes as measured by morphological alterations, lactate dehydrogenase leakage, cell viability, and apoptosis. Dox time- and concentration-dependently increased reactive oxygen species (ROS) formation in MT(+/+) cardiomyocytes, and this effect was exaggerated in MT(-/-) cardiomyocytes. Antioxidant N-acetylcysteine (NAC) and glutathione (GSH) significantly rescued MT(+/+) but not MT(-/-)cardiomyocytes from Dox-induced cell death and ROS generation. These findings suggest that basal MT provide protection against Dox-induced toxicity in cardiomyocytes, particularly highlight the important role of MT as a cellular antioxidant on scavenging ROS.

Native and reconstituted HDL protect cardiomyocytes from doxorubicin-induced apoptosis

AIMS

We analysed the impact of native and reconstituted HDL on doxorubicin-induced cardiomyocyte apoptosis. While it is an effective anti-cancer agent, doxorubicin has serious cardiotoxic side effects. HDL has been shown to protect cardiomyocytes, notably against oxidative stress.

METHODS AND RESULTS

Cultured neonatal rat ventricular cardiomyocytes were subjected to doxorubicin-induced stress, monitored as caspase3 activation, apoptotic DNA fragmentation and cell viability. The protective effects of HDL and sphingosine-1-phosphate (S1P) were investigated using native HDL, reconstituted HDL of varied composition and agonists and antagonists of S1P receptors. Anti-apoptotic signalling pathways were identified with specific inhibitors. Native and reconstituted HDL significantly decreased doxorubicin-induced cardiomyocyte apoptosis, essentially due to the S1P component of HDL. The latter was mediated by the S1P2 receptor, but not the S1P1 or S1P3 receptors. The extracellular signal-regulated kinases 1 and 2 (ERK1/2) signalling pathway was required for the anti-apoptotic effects of HDL and S1P. The transcription factor Stat3 also played an important role, as inhibition of its activity compromised the protective effects of HDL and S1P on doxorubicin-induced apoptosis.

CONCLUSION

HDL and its sphingosine-1-phosphate component can protect cardiomyocytes against doxorubicin toxicity and may offer one means of reducing cardiotoxic side effects during doxorubicin therapy. The study identified anti-apoptotic pathways that could be exploited to improve cardiomyocyte survival.

Determination of the absolute configurations of synthetic daunorubicin analogues using vibrational circular dichroism spectroscopy and density functional theory

The absolute configurations of three synthesized anthracycline analogues have been determined using vibrational circular dichroism (VCD) spectroscopy and the density functional theory (DFT) calculations. The experimental VCD spectra of the three compounds have been measured for the first time in the film state, prepared from their CDCl(3) solutions. Conformational searches for the monomers and some dimers of the three compounds have been performed at the DFT level using the B3LYP functional and the 6-311G** and 6-311++G** basis sets. The corresponding vibrational absorption and VCD spectra have been calculated. The good agreement between the experimental and the calculated spectra allows one to assign the absolute configurations of the three compounds with high confidence. In addition, the dominant conformers of the three compounds have also been identified.

TVP1022 protects neonatal rat ventricular myocytes against doxorubicin-induced functional derangements

Our recent studies demonstrated that propargylamine derivatives such as rasagiline (Azilect, Food and Drug Administration-approved anti-Parkinson drug) and its S-isomer TVP1022 protect cardiac and neuronal cell cultures against apoptotic-inducing stimuli. Studies on structure-activity relationship revealed that their neuroprotective effect is associated with the propargylamine moiety, which protects mitochondrial viability and prevents apoptosis by activating Bcl-2 and protein kinase C-epsilon and by down-regulating the proapoptotic protein Bax. Based on the established cytoprotective and neuroprotective efficacies of propargylamine derivatives, as well as on our recent study showing that TVP1022 attenuates serum starvation-induced and doxorubicin-induced apoptosis in neonatal rat ventricular myocytes (NRVMs), we tested the hypothesis that TVP1022 will also provide protection against doxorubicin-induced NRVM functional derangements. The present study demonstrates that pretreatment of NRVMs with TVP1022 (1 microM, 24 h) prevented doxorubicin (0.5 microM, 24 h)-induced elevation of diastolic [Ca(2+)](i), the slowing of [Ca(2+)](i) relaxation kinetics, and the decrease in the rates of myocyte contraction and relaxation. Furthermore, pretreatment with TVP1022 attenuated the doxorubicin-induced reduction in the protein expression of sarco/endoplasmic reticulum calcium (Ca(2+)) ATPase, Na(+)/Ca(2+) exchanger 1, and total connexin 43. Finally, TVP1022 diminished the inhibitory effect of doxorubicin on gap junctional intercellular coupling (measured by means of Lucifer yellow transfer) and on conduction velocity, the amplitude of the activation phase, and the maximal rate of activation (dv/dt(max)) measured by the Micro-Electrode-Array system. In summary, our results indicate that TVP1022 acts as a novel cardioprotective agent against anthracycline cardiotoxicity, and therefore potentially can be coadmhence, theinistered with doxorubicin in the treatment of malignancies in humans.

Alterations in brain antioxidant enzymes and redox proteomic identification of oxidized brain proteins induced by the anti-cancer drug adriamycin: implications for oxidative stress-mediated chemobrain

Adriamycin (ADR) is a chemotherapeutic for the treatment of solid tumors. This quinone-containing anthracycline is well known to produce large amounts of reactive oxygen species (ROS) in vivo. A common complaint of patients undergoing long-term treatment with ADR is somnolence, often referred to as "chemobrain." While ADR itself does not cross the blood brain barrier (BBB), we recently showed that ADR administration causes a peripheral increase in tumor necrosis factor alpha (TNF-alpha), which migrates across the BBB and leads to inflammation and oxidative stress in brain, most likely contributing to the observed decline in cognition. In the current study, we measured levels of the antioxidant glutathione (GSH) in brains of mice injected intraparitoneally (i.p.) with ADR, as well as the levels and activities of several enzymes involved in brain GSH metabolism. We observed significantly decreased GSH levels, as well as altered GSH/GSSG ratio in brains of ADR treated mice relative to saline-treated controls. Also observed in brains of ADR treated mice were increased levels of glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GR). We also observed increased activity of GPx, but a significant reduction in GST and GR activity in mice brain, 72 h post i.p. injection of ADR (20 mg/kg body weight). Furthermore, we used redox proteomics to identify specific proteins that are oxidized and/or have differential levels in mice brains as a result of a single i.p. injection of ADR. Visinin like protein 1 (VLP1), peptidyl prolyl isomerase 1 (Pin1), and syntaxin 1 (SYNT1) showed differential levels in ADR treated mice relative to saline-treated controls. Triose phosphate isomerase (TPI), enolase, and peroxiredoxin 1 (PRX-1) showed significantly increased specific carbonylation in ADR treated mice brain. These results further support the notion ADR induces oxidative stress in brain despite not crossing the BBB, and that antioxidant intervention may prevent ADR-induced cognitive dysfunction.

Skeletal Muscle for Endomyocardial Biopsy: Comparable Stress Response in Doxorubicin Cardio-myopathy

In the present study, we compared the cell damage response in skeletal and cardiac muscle tissue when exposed to doxorubicin. This was carried out by means of a less invasive informative substitute to endomyocardiac biopsy based on Hsp70 immunodetection and a subcellular analysis of the nucleolus. Male Sprague Dawley rats (62 g body weight) were randomly distributed into 3 group, the control and doxorubicin I and doxorubicin II groups, in which 15 and 25 mg/kg body weight of doxorubicin (0.1 ml, i.v.) was administered, respectively. After 15, 30, 45 and 60 minutes, portions of the left and right ventricle wall and interventricle wall, together with skeletal muscle from the posterior and anterior member, were prepared for Hsp70 immunodetection by Western blot analysis and ultrastructural study using the thin cut technique. Differential cell response between the control and treated groups was observed in Hsp70 immunodetection and at the subcellular level. In the control group, the Hsp70 recognition levels and typical normal nucleolar morphology were similar, while the treated groups showed variable-dependent Hsp70 recognition and segregation of nucleolar components, forming ring-like figures of a variable-independent nature. Comparison of cardiac and skeletal muscle tissue cell response to doxorubicin toxic aggression revealed parallelism in terms of Hsp70 accumulation in certain regions of both tissues (15 mg/kg body weight of doxorubicin), which suggests that replacing endomyocardiac biopsy analysis with skeletal muscle analysis may be a safe option.

Improving outcome of chemotherapy of metastatic breast cancer by docosahexaenoic acid: a phase II trial

BACKGROUND

Breast cancer becomes lethal when visceral metastases develop. At this stage, anti-cancer treatments aim at relieving symptoms and delaying death without resulting in additional toxicity. On the basis of their differential anti-oxidant defence level, tumour cells can be made more sensitive to chemotherapy than non-tumour cells when membrane lipids are enriched with docosahexaenoic acid (DHA), a peroxidisable and oxidative-stress-inducing lipid of marine origin.

METHODS

This open-label single-arm phase II study evaluated the safety and efficacy (response rate), as primary end points, of the addition of 1.8 g DHA daily to an anthracycline-based chemotherapy (FEC) regimen in breast cancer patients (n = 25) with rapidly progressing visceral metastases. The secondary end points were time to progression (TTP) and overall survival (OS).

RESULTS

The objective response rate was 44%. With a mean follow-up time of 31 months (range 2-96 months), the median TTP was 6 months. Median OS was 22 months and reached 34 months in the sub-population of patients (n = 12) with the highest plasma DHA incorporation. The most common grade 3 or 4 toxicity was neutropaenia (80%).

CONCLUSION

DHA during chemotherapy was devoid of adverse side effects and can improve the outcome of chemotherapy when highly incorporated. DHA has a potential to specifically chemosensitise tumours.

A concise description of cardioprotective strategies in doxorubicin-induced cardiotoxicityThis article is one of a selection of papers published in a special issue celebrating the 125th anniversary of the Faculty of Medicine at the University of Manitoba

Doxorubicin (Dox) is frequently used as a frontline chemotherapeutic agent against a variety of cancers. Tremendous progress has been made on its optimal usage over the last 40 years. However, cardiotoxicity still remains a major concern. The great promise in this matter is that the mechanisms leading to antitumor activity appear to be different from those leading to Dox-induced cardiomyopathy. In this regard, various cardioprotective agents have been discussed. Attention should be drawn to probucol, a lipid-lowering agent with potent antioxidant properties, which provides complete protection against Dox-induced cardiomyopathy in rats without interfering with the antitumor properties of Dox in an experimental setting. Clinical trials employing Dox therapy in combination with probucol are needed to determine whether the outstanding findings in animal experiments can be extrapolated to clinical results. We have much further to go before the establishment of cancer therapies without any risk of cardiac side effects.

Synthesis and DNA-binding affinity studies of glycosylated intercalators designed as functional mimics of the anthracycline antibiotics

Anthracycline antibiotics such as daunomycin (Dauno) and doxorubicin (Dox) are well-known clinically used cancer chemotherapeutics, which, among other mechanisms, bind to DNA, thereby triggering a cascade of biological responses leading to cell death. However, anthracyclines are cardiotoxic, and drug resistance develops rapidly, thus limiting their clinical use. We report here the synthesis and DNA-binding affinity of a novel class of functional anthracycline mimetics consisting of an aromatic moiety linked to a carbohydrate (1-12). In the targets, the aromatic core consists of a 2-phenylbenzo[b]furan-3-yl, 2-phenylbenzo[b]thiophen-3-yl, 1-tosyl-2-phenylindol-3-yl, or 2-phenylindol-3-yl group that is bound to one of three aminosugars (daunosamine, acosamine, or 4-amino-2,3,4,6-tetradeoxy-alpha-l-hexopyranoside) via a propargyl linker. The DNA binding affinity of these twelve compounds has been evaluated by using both direct and indirect fluorescence measurements. Compared to Dauno and Dox, the DNA binding affinity of these analogues is weaker. However, both aromatic and aminosugar motifs are critical to DNA binding, with more influence coming from the structural features of the aromatic portion.

Astragalus Improved Cardiac Function of Adriamycin-Injured Rat Hearts by Upregulation of SERCA2a Expression

The traditional Chinese medical herb Astragalus, the dried root of Astragalus membranaceus (Fisch.) Bge., has been widely applied to treat patients with cardiovascular disease in China and has profound cardioprotective effects. This study investigated the effect of Astragalus on hemodynamic changes in adriamycin (ADR)-injured rat hearts and its underlying molecular mechanism. Sprague-Dawley rats were divided into four groups: control, ADR only, ADR + low dose of Astragalus and ADR + high dose of Astragalus. Rats were injected intraperitoneally with 6 equal doses of ADR (cumulative dose, 12 mg/kg) over a period of 2 weeks. Treatment of Astragalus began 1 day before the onset of ADR injection and was given orally once a day for 50 days (3.3 or 10 g/kg/day). Five weeks after the final injection of ADR, rats treated with ADR only showed a significant inhibition of cardiac diastolic function accompanied by the presence of ascites, a remarkable reduction in body weight and heart weight as well as survival rate compared to the controls. Moreover, SERCA2a mRNA and protein expressions in hearts were obviously downregulated by ADR. However, this impaired cardiac function was significantly improved in both doses of Astragalus feeding groups. The amount of ascites was also reduced in a similar extent in these 2 groups. Only the high dose treatment of Astragalus significantly attenuated the changes of SERCA2a expression in injured hearts and improved survival. These results indicated that Astragalus could improve cardiac function of ADR-injured rat hearts, which was partly mediated by upregulation of SERCA2a expression.

NADPH oxidases participate to doxorubicin-induced cardiac myocyte apoptosis

Cumulative doses of doxorubicin, a potent anticancer drug, lead to serious myocardial dysfunction. Numerous mechanisms including apoptosis have been proposed to account for its cardiotoxicity. Cardiac apoptosis induced by doxorubicin has been related to excessive reactive oxygen species production by the mitochondrial NADH dehydrogenase. Here, we explored whether doxorubicin treatment activates other superoxide anion generating systems such as the NADPH oxidases, membrane-embedded flavin-containing enzymes, and whether the subsequent oxidative stress contributes to apoptosis. We showed that doxorubicin treatment of rat cardiomyoblasts H9c2 triggers increases in caspase-3 like activity and hypoploid cells, both common features of apoptosis. Doxorubicin exposure also leads to a rapid superoxide production through NADPH oxidase activation. Inhibition of these enzymes using diphenyliodonium and apocynin reduces doxorubicin-induced reactive oxygen species production, caspase-3 like activity and sub-G1 cell population. In conclusion, NADPH oxidases participate to doxorubicin-induced cardiac apoptosis.

Concurrent decline of several antioxidants and markers of oxidative stress during combination chemotherapy for small cell lung cancer

OBJECTIVES

To investigate the oxidant effects of adriamycin-containing chemotherapy (CT), we evaluated various antioxidants, total antioxidant capacity (TRAP) and different parameters of oxidative and nitrosative stress during combination CT.

DESIGN AND METHODS

Blood samples were obtained from 16 small cell lung cancer patients at baseline and several times during the first, second and sixth CT cycles.

RESULTS

There were significant decreases in serum urate and serum proteins during all cycles, serum TRAP during the first two cycles, plasma ascorbic acid and serum TBARS during the first cycle, and serum conjugated dienes and plasma alphatocopherol during the last cycle. The baseline levels of tocopherols increased significantly between the first and sixth CT cycles. Higher levels of baseline plasma thiols were associated with better overall survival (p=0.008).

CONCLUSIONS

Adriamycin-containing CT causes significant oxidative stress as implied by reduced levels of protective antioxidants. Long-term CT treatment seems to enhance lipid peroxidation.

Overexpression of CYP2J2 provides protection against doxorubicin-induced cardiotoxicity

Human cytochrome P-450 (CYP)2J2 is abundant in heart and active in biosynthesis of epoxyeicosatrienoic acids (EETs). Recently, we demonstrated that these eicosanoid products protect myocardium from ischemia-reperfusion injury. The present study utilized transgenic (Tr) mice with cardiomyocyte-specific overexpression of human CYP2J2 to investigate protection toward toxicity resulting from acute (0, 5, or 15 mg/kg daily for 3 days, followed by 24-h recovery) or chronic (0, 1.5, or 3.0 mg/kg biweekly for 5 wk, followed by 2-wk recovery) doxorubicin (Dox) administration. Acute treatment resulted in marked elevations of serum lactate dehydrogenase and creatine kinase levels that were significantly greater in wild-type (WT) than CYP2J2 Tr mice. Acute treatment also resulted in less activation of stress response enzymes in CYP2J2 Tr mice (catalase 750% vs. 300% of baseline, caspase-3 235% vs. 165% of baseline in WT vs. CYP2J2 Tr mice). Moreover, CYP2J2 Tr hearts exhibited less Dox-induced cardiomyocytes apoptosis (measured by TUNEL) compared with WT hearts. After chronic treatment, comparable decreases in body weight were observed in WT and CYP2J2 Tr mice. However, cardiac function, assessed by measurement of fractional shortening with M-mode transthoracic echocardiography, was significantly higher in CYP2J2 Tr than WT hearts after chronic Dox treatment (WT 37 +/- 2%, CYP2J2 Tr 47 +/- 1%). WT mice also had larger increases in beta-myosin heavy chain and cardiac ankryin repeat protein compared with CYP2J2 Tr mice. CYP2J2 Tr hearts had a significantly higher rate of Dox metabolism than WT hearts (2.2 +/- 0.25 vs. 1.6 +/- 0.50 ng.min(-1).100 microg protein(-1)). In vitro data from H9c2 cells demonstrated that EETs attenuated Dox-induced mitochondrial damage. Together, these data suggest that cardiac-specific overexpression of CYP2J2 limited Dox-induced toxicity.

Two nonsynonymous single nucleotide polymorphisms of human carbonyl reductase 1 demonstrate reduced in vitro metabolism of daunorubicin and doxorubicin

Carbonyl reductases (CBRs) are a group of metabolic enzymes belonging to the short-chain dehydrogenase family with NADPH-dependent oxidoreductase activity. These enzymes are known to metabolize the anthracyclines doxorubicin (DOX) and daunorubicin (DAUN). Both DOX and DAUN are highly effective in cancer therapy; however, there is considerable interpatient variability in adverse effects seen in patients undergoing treatment with these drugs. This may be attributed to altered metabolism associated with nonsynonymous single nucleotide polymorphisms (ns-SNPs) in the genes encoding for CBRs. In this study, we examine the effect of the V88I and P131S mutations in the human CBR1 gene on the metabolism of anthracyclines to their respective major metabolites, doxorubicinol and daunorubicinol. Kinetic studies using purified, histidine-tagged, recombinant enzymes in a high-performance liquid chromatography-fluorescence assay demonstrated that the V88I mutation leads to a significantly reduced maximal rate of activity (V(max)) (2090 +/- 112 and 257 +/- 11 nmol/min x mg of purified protein for DAUN and DOX, respectively) compared with that for the wild-type (3430 +/- 241 and 364 +/- 37 nmol/min x mg of purified protein for DAUN and DOX, respectively). In the case of the P131S mutation, a significant increase in substrate affinity (K(m)) was observed for DAUN only (89 +/- 13 microM) compared with that for the wild-type (51 +/- 13 microM). In the presence of either anthracycline, both variants exhibited a 20 to 40% decrease in catalytic efficiency (k(cat)/K(m)) compared with that for the wild-type enzyme. Therefore, the ns-SNPs generating both these mutations may alter bioavailability of these anthracyclines in cancer patients and should be examined in clinical studies as potential biomarkers for DAUN- and DOX-induced adverse effects.

Role of superoxide, nitric oxide, and peroxynitrite in doxorubicin-induced cell death in vivo and in vitro

Doxorubicin (DOX) is a potent available antitumor agent; however, its clinical use is limited because of its cardiotoxicity. Cell death is a key component in DOX-induced cardiotoxicity, but its mechanisms are elusive. Here, we explore the role of superoxide, nitric oxide (NO), and peroxynitrite in DOX-induced cell death using both in vivo and in vitro models of cardiotoxicity. Western blot analysis, real-time PCR, immunohistochemistry, flow cytometry, fluorescent microscopy, and biochemical assays were used to determine the markers of apoptosis/necrosis and sources of NO and superoxide and their production. Left ventricular function was measured by a pressure-volume system. We demonstrated increases in myocardial apoptosis (caspase-3 cleavage/activity, cytochrome c release, and TUNEL), inducible NO synthase (iNOS) expression, mitochondrial superoxide generation, 3-nitrotyrosine (NT) formation, matrix metalloproteinase (MMP)-2/MMP-9 gene expression, poly(ADP-ribose) polymerase activation [without major changes in NAD(P)H oxidase isoform 1, NAD(P)H oxidase isoform 2, p22(phox), p40(phox), p47(phox), p67(phox), xanthine oxidase, endothelial NOS, and neuronal NOS expression] and decreases in myocardial contractility, catalase, and glutathione peroxidase activities 5 days after DOX treatment to mice. All these effects of DOX were markedly attenuated by peroxynitrite scavengers. Doxorubicin dose dependently increased mitochondrial superoxide and NT generation and apoptosis/necrosis in cardiac-derived H9c2 cells. DOX- or peroxynitrite-induced apoptosis/necrosis positively correlated with intracellular NT formation and could be abolished by peroxynitrite scavengers. DOX-induced cell death and NT formation were also attenuated by selective iNOS inhibitors or in iNOS knockout mice. Various NO donors when coadministered with DOX but not alone dramatically enhanced DOX-induced cell death with concomitant increased NT formation. DOX-induced cell death was also attenuated by cell-permeable SOD but not by cell-permeable catalase, the xanthine oxidase inhibitor allopurinol, or the NADPH oxidase inhibitors apocynine or diphenylene iodonium. Thus, peroxynitrite is a major trigger of DOX-induced cell death both in vivo and in vivo, and the modulation of the pathways leading to its generation or its effective neutralization can be of significant therapeutic benefit.

In vivo amelioration of adriamycin induced oxidative stress in plasma by gamma-glutamylcysteine ethyl ester (GCEE)

Adriamycin (ADR) is a common chemotherapeutic known to generate significant amounts of reactive oxygen species (ROS). Although ROS generation is one of several means by which ADR attacks cancerous tissues, oxidative stress-related toxicity has been documented in several non-targeted organs as a result of anthracycline chemotherapy. Oxidative damage to tissues has been shown in the past to be minimized with co-administration of various antioxidants. Gamma-glutamylcysteine ethyl ester (GCEE) is an antioxidant and precursor to glutathione that has been shown to successfully defend brain against ADR-induced oxidative stress. The current study shows ADR in vivo also causes oxidative stress in plasma in the form of protein oxidation [indexed by protein carbonyls and protein bound 3-nitrotyrosine] and lipid peroxidation [indexed by protein-bound-4-hydroxynonenal]. All three markers of oxidative stress are significantly suppressed with in vivo co-administration of GCEE. This work further supports the concept that administration of GCEE can protect patients undergoing anthracycline chemotherapy from non-targeted oxidative damage.

Pretreatment with statin attenuates the cardiotoxicity of Doxorubicin in mice

Cardiotoxicity, which may result from intense cardiac oxidative stress and inflammation, is the main limiting factor of the anticancer therapy using doxorubicin. Because statins might exert beneficial pleiotropic cardiovascular effects, among other things, by anti-inflammatory and antioxidative mechanisms, we investigated whether or not fluvastatin pretreatment can attenuate doxorubicin-induced cardiotoxicity. Five days after a single injection of doxorubicin (20 mg/kg; i.p.), left ventricular (LV) function was measured in fluvastatin-treated (DoxStatin; 100 mg/kg/day, p.o.) and saline-treated (doxorubicin) mice (n = 8 per group) by a micro conductance catheter. Untreated mice served as controls (placebo; n = 8 per group). After measurement of cardiac function, LV tissues were analyzed by molecular biological and immunohistologic methods. Injection resulted in significantly impaired LV function (LV pressure, -29%; dp/dtmax, -45%; cardiac output, -68%; P < 0.05) when compared with placebo. This was associated with a significant increase in cardiac oxidative stress, inflammation and apoptotic mechanisms, as indicated by significant increased cardiac lipid peroxidation activity, protein expression of nitrotyrosine, tumor necrosis factor alpha and Bax (P < 0.05). In contrast, DoxStatin mice showed improved LV function (LV pressure, +24%; dp/dtmax, +87%; cardiac output, +87%; P < 0.05) when compared with untreated doxorubicin mice. This was associated with reduced cardiac expression of nitrotyrosine, enhanced expression of the mitochondrial located antioxidative SOD 2, attenuated mitochondrial apoptotic pathways, and reduced cardiac inflammatory response. Statin pretreatment attenuates doxorubicin-induced cardiotoxicity via antioxidative and anti-inflammatory effects.

Trastuzumab and Doxorubicin-Related Cardiotoxicity and the Cardioprotective Role of Exercise

Women diagnosed with breast cancer typically undergo a multimodal approach to treating their disease. The treatments used often result in sequelae such as fatigue, hair loss, nausea and vomiting, and functional impairment. Many of these sequelae can be controlled or eliminated with pharmacological, physical, or social interventions. However, 2 effective cytotoxic agents, doxorubicin and trastuzumab, are associated with a potentially life-threatening sequela, cardiotoxicity. Currently, these agents are dosage and duration limited to circumvent cardiac damage. Exercise prior to and during the administration of these agents is emerging as a possible cardioprotective intervention based on the findings of animal model studies. Incorporating exercise into the breast cancer treatment trajectory may eliminate the dosage and duration restrictions of these antineoplastic agents and ultimately affect survival and quality of life. The authors present the pharmacological mechanism for each agent and the exciting results of animal model studies that lay the groundwork for future clinical trials.

Aqueous fish extract increases survival in the mouse model of cytostatic toxicity

Background

Treatment of cancer patients with anthracycline antibiotic doxorubicin (DOX) may be complicated by development of acute and chronic congestive heart failure (CHF), malignant arrhythmias and death. The aim of this study was to test whether an aqueous low molecular weight (LMW) extract from cod muscle decreases acute mortality in the mouse model of acute CHF caused by DOX.

Methods

A LMW fraction (<500 Da) of the aqueous phase of cod light muscle (AOX) was used for treatment of male BALB/c mice (~25 g, n = 70). The animals were divided into four groups, DOX + AOX (n = 20), DOX + saline (NaCl) (n = 30), NaCl + AOX (n = 10) and NaCl only (n = 10). Echocardiography was performed in the separate subgroups (DOX treated n = 6 and controls n = 6) to verify the presence and the grade of acute CHF. The cod extract was delivered by subcutaneously implanted osmotic minipumps over the period of 2 weeks. High-dose injection of DOX was administered to randomly selected animals. The animals received single intraperitoneal injection of DOX (25 mg/kg) and were followed over two weeks for mortality.

Results

Mortality rate was 68% lower (p < 0.05) in the mice treated with the extract. The analyses of cod extract have shown strong antioxidative effect in vitro.

Conclusion

The aqueous LMW cod muscles extract decreases mortality in the mouse model of DOX induced acute CHF. This effect may be mediated by cardioprotection through antioxidative mechanisms.

Heat shock protein 20 interacting with phosphorylated Akt reduces doxorubicin-triggered oxidative stress and cardiotoxicity

Doxorubicin (DOX) is a widely used antitumor drug, but its application is limited because of its cardiotoxic side effects. Heat shock protein (Hsp)20 has been recently shown to protect cardiomyocytes against apoptosis, induced by ischemia/reperfusion injury or by prolonged beta-agonist stimulation. However, it is not clear whether Hsp20 would exert similar protective effects against DOX-induced cardiac injury. Actually, DOX treatment was associated with downregulation of Hsp20 in the heart. To elucidate the role of Hsp20 in DOX-triggered cardiac toxicity, Hsp20 was first overexpressed ex vivo by adenovirus-mediated gene delivery. Increased Hsp20 levels conferred higher resistance to DOX-induced cell death, compared to green fluorescent protein control. Furthermore, cardiac-specific overexpression of Hsp20 in vivo significantly ameliorated acute DOX-triggered cardiomyocyte apoptosis and animal mortality. Hsp20 transgenic mice also showed improved cardiac function and prolonged survival after chronic administration of DOX. The mechanisms underlying these beneficial effects were associated with preserved Akt phosphorylation/activity and attenuation of DOX-induced oxidative stress. Coimmunoprecipitation studies revealed an interaction between Hsp20 and phosphorylated Akt. Accordingly, BAD phosphorylation was preserved, and cleaved caspase-3 was decreased in DOX-treated Hsp20 transgenic hearts, consistent with the antiapoptotic effects of Hsp20. Parallel ex vivo experiments showed that either infection with a dominant-negative Akt adenovirus or preincubation of cardiomyocytes with the phosphatidylinositol 3-kinase inhibitors significantly attenuated the protective effects of Hsp20. Taken together, our findings indicate that overexpression of Hsp20 inhibits DOX-triggered cardiac injury, and these beneficial effects appear to be dependent on Akt activation. Thus, Hsp20 may constitute a new therapeutic target in ameliorating the cardiotoxic effects of DOX treatment in cancer patients.

A mouse model for juvenile doxorubicin-induced cardiac dysfunction

Doxorubicin (DOX) is a potent antitumor 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 1 wk. Here, we describe a juvenile mouse model of chronic DOX-induced cardiac dysfunction. DOX treatment was initiated at 2 wk of age and continued for a period of 5 wk (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 wk after the final DOX injection. Cardiac systolic function improved during this recovery period but remained depressed compared with the saline injected controls, despite the reversal of cardiac atrophy. Interestingly, increased levels of cardiomyocyte apoptosis and concomitant myocardial fibrosis were observed after DOX withdrawal. These data suggest that different mechanisms contribute to cardiac dysfunction during the treatment and recovery phases.

Angiogenesis without functional outcome after mononuclear stem cell transplant in a doxorubicin-induced dilated myocardiopathy murine model

OBJECTIVES

Cell transplantation is considered a novel approach in the treatment of myocardiopathy. The objective of this study was to evaluate the effects of autologous mononuclear stem cell therapy in doxorubicin-induced dilated myocardiopathy by conducting both functional and histopathologic analysis.

METHODS

Seventy male rats were doxorubicin injected intraperitoneally for 2 weeks. At 1 month, the animals that had demonstrated left ventricular ejection fractions less than 40% were randomly divided into a mononuclear stem cell group and controls. Mononuclear stem cells were isolated. All animals underwent echocardiographic study: baseline, pre-cell therapy, and at 1 month post-cell therapy, and analyzed by the nonparametric Mann-Whitney test. Transplants were performed by subepicardial injections. Standard staining was performed.

RESULTS

Twenty-three animals were randomly treated: mononuclear stem cell and control groups, with 11 rats completing the study. Cell viability was 85%. Mononuclear stem cells (n=5; 5x106 cells /300 microL medium) and control (n=6; 300 microL medium) were used. The resulting left ventricular ejection fraction in the cell therapy group was not significantly different compared with controls (p=0.54). New vessels were demonstrated in the subepicardial region.

CONCLUSIONS

Autologous mononuclear stem cell therapy was not functionally effective in doxorubicin-induced dilated myocardiopathy in the animal model under study with the experimental conditions, despite occurrence of angiogenic activity.

ERKs/p53 signal transduction pathway is involved in doxorubicin-induced apoptosis in H9c2 cells and cardiomyocytes

The cardiotoxic effects of doxorubicin, a potent chemotherapeutic agent, have been linked to DNA damage, oxidative mitochondrial damage, and nuclear translocation of p53, but the exact molecular mechanisms causing p53 transactivation and doxorubicin-induced cardiomyopathy are not clear. The present study was carried out to determine whether extracellular signal-regulated kinases (ERKs), which are known to be activated by DNA damaging agents, are responsible for doxorubicin-induced p53 activation and oxidative mitochondrial damage in H9c2 cells. Cell death was measured by terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling, annexin V-fluorescein isothiocyanate, activation of caspase-9 and -3, and cleavage of poly(ADP-ribose) polymerase (PARP). We found that doxorubicin produced cell death in H9c2 cells in a time-dependent manner, beginning at 6 h, and these changes are associated decreased expression of Bcl-2, increases in Bax and p53 upregulated modulator of apoptosis-alpha expression, and collapse of mitochondria membrane potential. The changes in cell death and Bcl-2 family proteins, however, were preceded by earlier activation and nuclear translocation of ERKs, followed by increased phosphorylation at Ser15 and nuclear translocation of the phosphorylated p53. The functional importance of ERK1/2 and p53 in doxorubicin-induced toxicity was further demonstrated by the specific ERK inhibitor U-0126 and p53 inhibitor pifithrin (PFT)-alpha, which abrogated the changes in Bcl-2 family proteins and cell death produced by doxorubicin. U-0126 blocked the phosphorylation and nuclear translocation of both ERK1/2 and p53, whereas PFT-alpha blocked only the changes in p53. Doxorubicin and ERK inhibitors produced similar changes in ERK1/2-p53, PARP, and caspase-3 in neonatal rat cultured cardiomyocytes. Thus we conclude that ERK1/2 are functionally linked to p53 and that the ERK1/2-p53 cascade is the upstream signaling pathway responsible for doxorubicin-induced cardiac cell apoptosis. ERKs and p53 may be considered as novel therapeutic targets for the treatment of doxorubicin-induced cardiotoxicity.

Cognitive dysfunction induced by chronic administration of common cancer chemotherapeutics in rats

Although cognitive dysfunction manifested by severe memory and attention deficits has been reported in up to 70% of cancer patients undergoing chemotherapy, the mechanisms of this serious side effect have not been defined. In particular, it has not been decisively resolved whether the dysfunction is attributable to the chemotherapy or to the malignancy itself. In the present study we tested whether cognitive dysfunction can be induced in an experimental setting by the administration of commonly used chemotherapeutics to rats. Female 10 month old Sprague-Dawley rats were injected intraperitoneally with a combination of 2.5 mg/kg of adriamycin (ADR) and 25 mg/kg of cytoxan (CTX). A total of four doses were given at weekly intervals. The control group was treated with saline only. No mortality and no apparent morbidity were observed in either group. However, the chemotherapeutic treatment severely impaired memory function of rats as measured by a passive avoidance test. This memory deficiency was fully prevented by the administration of an antioxidant, N-acetyl cysteine (NAC) injected subcutaneously three times a week at 200 mg/kg in the course of chemotherapeutic treatment. These results indicate that chemotherapeutic agents alone, i.e., in the absence of malignancy, damage the brain resulting in memory dysfunction. Moreover, the results strongly indicate that the damaging effect is mediated by oxidative stress, as memory dysfunction is preventable by the co-administration of NAC.

Protective effect of Zingiber officinale roscoe against anticancer drug doxorubicin-induced acute nephrotoxicity

Oxidative stress due to abnormal production of reactive oxygen species has been implicated in the nephrotoxicity induced by a commonly used anticancer antibiotic doxorubicin (DXN). The nephroprotective effect of aqueous ethanol extract of Zingiber officinale (200 and 400mg/kg, p.o) was evaluated against doxorubicin-induced (15mg/kg, i.p) acute renal damage in rat. Serum urea and creatinine levels were evaluated as the markers of renal failure. Renal antioxidant status such as activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and level of reduced glutathione (GSH) were determined. Level of lipid peroxidation as equivalents of malondialdehyde (MDA), and glutathione-S-transferase (GST) activity were determined in the kidneys. Serum urea and creatinine levels were reduced in the Z. officinale (200 and 400mg/kg, p.o) plus DXN treated groups. The renal antioxidant enzymes activities such as SOD, CAT GPx, levels of GSH and GST activity were restored and that of MDA declined significantly (p<0.001) in the Z. officinale (400mg/kg) plus DXN treated group. The nephroprotection is mediated by preventing the DXN-induced decline of renal antioxidant status, and also by increasing the activity of GST.

Melatonin controls oxidative stress and modulates iron, ferritin, and transferrin levels in adriamycin treated rats

AIM

Chemotherapy with adriamycin (ADR) is limited by its iron-mediated pro-oxidant toxicity. Because melatonin (MLT) is a broad spectrum antioxidant, we investigated the ability of MLT to control iron, its binding proteins, and the oxidative damage induced by ADR.

MAIN METHODS

ADR was given as single i.p. dose of 10 mg kg(-1) body weight into male rats. MLT at a dose of 15 mg kg(-1) was injected daily for 5 days before ADR treatment followed by another injection for 5 days. Biochemical methods were used for this investigation.

KEY FINDINGS

ADR injection caused elevations in plasma creatine kinase isoenzyme, lactic dehydrogenase, and aminotransferases, iron, ferritin, and transferrin. These changes were associated with increases in lipid peroxidation and protein oxidation as well as decreases in glutathione (GSH) levels and glutathione-S-transferase (GST) activity, while glutathione peroxidase (GSH-Px), and catalase (CAT) activity were elevated in the heart and liver of ADR treated rats. In the MLT+ADR group, the cardiac and hepatic function parameters and the levels of iron, transferrin and ferritin in plasma were normalized to control levels. The rats that were subjected to MLT+ADR had normalized CAT and GSH-Px activity and decreased TBARS and protein carbonyl levels compared the group only treated with ADR. GST activity and GSH concentration in the heart and liver were normalized when MLT accompanied ADR treatment.

SIGNIFICANCE

MLT ameliorated oxidative stress by controlling iron, and binding protein levels in ADR treated rats demonstrating the usefulness of adriamycin in cancer chemotherapy and allowing a better management of iron levels.

Two allelic variants of aldo-keto reductase 1A1 exhibit reduced in vitro metabolism of daunorubicin

Aldo-keto reductases (AKRs) are a class of NADPH-dependent oxidoreductases that have been linked to metabolism of the anthracyclines doxorubicin (DOX) and daunorubicin (DAUN). Although widely used, cardiotoxicity continues to be a serious side effect that may be linked to metabolites or reactive intermediates generated in their metabolism. In this study we examine the little known effects of nonsynonymous single nucleotide polymorphisms of human AKR1A1 on the metabolism of these drugs to their alcohol metabolites. Expressed and purified from bacteria using affinity chromatography, the AKR1A1 protein with a single histidine (6x-His) tag exhibited the greatest activity using two test substrates: p-nitrobenzaldehyde (5.09 +/- 0.16 micromol/min/mg of purified protein) and DL-glyceraldehyde (1.24 +/- 0.17 micromol/min/mg). These activities are in agreement with published literature values of nontagged human AKR1A1. The 6x-His-tagged AKR1A1 wild type and allelic variants, E55D and N52S, were subsequently examined for metabolic activity using DAUN and DOX. The tagged variants showed significantly reduced activities (1.10 +/- 0.42 and 0.72 +/- 0.47 nmol of daunorubicinol (DAUNol) formed/min/mg of purified protein for E55D and N52S, respectively) compared with the wild type (2.34 +/- 0.71 nmol/min/mg). The wild type and E55D variant metabolized DOX to doxorubicinol (DOXol); however, the levels fell below the limit of quantitation (25 nM). The N52S variant yielded no detectable DOXol. A kinetic analysis of the DAUN reductase activities revealed that both amino acid substitutions lead to reduced substrate affinity, measured as significant increases in the measured K(m) for the reduction reaction by AKR1A1. Hence, it is possible that these allelic variants can act as genetic biomarkers for the clinical development of DAUN-induced cardiotoxicity.

Enhanced anti-tumor effects achieved in a murine tumor model using combination therapy of recombinant human manganese superoxide dismutase and adriamycin

Manganese superoxide dismutase (MnSOD) is the only primary antioxidant enzyme in mitochondria that scavenges superoxide radicals. Overexpressing MnSOD in cancer cells by cDNA transfection suppresses tumor formation and reverses malignant growth. In this study, we examined the effect of recombinant human manganese superoxide dismutase (rhMnSOD) alone and in combination with adriamycin (ADR) against solid tumors of sarcoma 180 in Institute of Cancer Research (ICR) mice. Administration of rhMnSOD alone and in combination with ADR significantly inhibited tumor growth in a dose-dependent manner. The use of rhMnSOD in combination with ADR enhanced ADR's anti-tumor potency without increasing toxicity. Histopathological examination provided evidence of the anti-tumor effect. In addition, we found lymphocyte infiltration of the tumors, with an increase in both CD4- and CD8-positive cells in the treated tumors. The expression of CD4 and CD8 was up-regulated with increasing dose of rhMnSOD, and the combination treatment with ADR further enhanced this up-regulation. Collectively, these data indicate that rhMnSOD may exhibit an anti-tumor effect by stimulating the immune system and promoting the recruitment of lymphocytes into the tumor to kill tumor cells. Thus MnSOD may constitute a potential new therapeutic agent to be exploited as an adjuvant in cancer therapy.

Cardioprotective effects of fullerenol C(60)(Oh)(24) on a single dose doxorubicin-induced cardiotoxicity in rats with malignant neoplasm

The therapeutic utility of the anthracycline antibiotic doxorubicin is limited due to its cardiotoxicity. Our aim was to investigate the efficacy of fullerenol C(60)(OH)(24) in preventing single, high-dose doxorubicin-induced cardiotoxicity in rats with malignant neoplasm. Experiment was performed on adult female Sprague Dawley rats with chemically induced mammary carcinomas. The animals were sacrificed two days after the application of doxorubicin and/or fullerenol, and the serum activities of CK, LDH and alpha-HBDH, as well as the levels of MDA, GSH, GSSG, GSH-Px, SOD, CAT, GR, and TAS in the heart, were determined. The results obtained from the enzymatic activity in the serum show that the administration of a single dose of 8 mg/kg in all treated groups induces statistically significant damage. There are significant changes in the enzymes of LDH and CK (p < 0.05), after an i.p. administration of doxorubicin/fullerenol and fullerenol. Comparing all groups with untreated control group, point to the conclusion that in the case of a lower alpha-HBDH/LDH ratio, results in more serious the liver parenchymal damage. The results revealed that doxorubicin induced oxidative damage and that the fullerenol antioxidative influence caused significant changes in MDA, GSH, GSSG, GSH-Px, SOD, CAT, GR, and TAS level in the heart (p < 0.05). Therefore, it is suggested that fullerenol might be a potential cardioprotector in doxorubicin-treated individuals.

Doxorubicin-induced myocardial failure in rats with malignant neoplasm: Protective role of fullerenol C60(OH)24

The therapeutic utility of the anthracycline antibiotic doxorubicin is limited due to its cardiotoxicity. Our aim was to investigate the efficacy of fullerenol C60(OH)24 in preventing single, high-dose doxorubicin-induced cardiotoxicity in rats with malignant neoplasm. In vitro and in vivo studies have shown that fullerenol C60(OH)24, has strong antioxidative potential. Experiment was performed on adult female Sprague Dawley rats with chemically induced mammary carcinomas. All 32 rats (2-5 groups) received i.p. applications of 1-methyl-l-nitrosourea (MNU; 50 mg/kg body weight) on the 50th and 113th day of age. Animals were randomly divided into five groups as follows: (1) Untreated control group - rats received saline only; (2) Cancer control group - rats received MNU and saline; (3) Dox group - rats received MNU and Dox 8 mg/kg; (4) Full/Dox group -rats received MNU and Full 100 mg/kg 30 min before Dox 8 mg/kg; (5) Full group - rats received MNU and Full 100 mg/kg. Tumor incidence was 4.94 +- 0.576 per rat. The animals were sacrificed 2 days after the application of doxorubicin and/or fullerenol, and the serum activities of CK, LDH and ?-HBDH, as well as the levels of MDA, GSH, GSSG, GSH-Px, SOD, CAT, GR and TAS in the heart, were determined. The results obtained from the enzymatic activity in the serum show that the administration of a single dose of 8 mg/kg in all treated groups induces statistically significant damage. There are significant changes in the enzymes of LDH and CK (p < 0.05), after an i.p. administration of doxorubicin/fullerenol and fullerenol. Comparing all groups with untreated control group, point to the conclusion that in the case of a lower oc-HBDH/LDH ratio, results in more serious the liver parenchymal damage. The results revealed that doxorubicin induced oxidative damage and that the fullerenol antioxidative influence caused significant changes in MDA, GSH, GSSG, GSH-Px, SOD, CAT, GR and TAS level in the heart (p < 0.05). Ultra structural analysis of heart tissues from rats treated with doxorubicin and indicated that the hearts of the rats were protected from doxorubicin-induced subcellular damage. Doxorubicin/fullerenol rats did not appear to show significant cardiac damage although occasional focal loss of cristae in the mitochondria was observed. Therefore, it is suggested that fullerenol might be a potential cardioprotector in doxorubicin-treated individuals.

Persistent alterations to the gene expression profile of the heart subsequent to chronic Doxorubicin treatment

Doxorubicin (DOX, Adriamycin) is a potent antineoplastic agent used to treat a number of cancers. Despite its utility, DOX causes a cumulative, irreversible cardiomyopathy that may become apparent shortly after treatment or years subsequent to therapy. Numerous studies have been conducted to elucidate the basis of DOX cardiotoxicity, but the precise mechanism responsible remains elusive. This investigation was designed to assess global gene expression using microarrays in order to identify the full spectrum of potential molecular targets of DOX cardiotoxicity to further delineate the underlying pathological mechanism(s) responsible for this dose-limiting cardiomyopathy. Male, Sprague-Dawley rats received 6 weekly injections of 2 mg/kg (s.c.) DOX followed by a 5 week drug-free period prior to analysis of cardiac tissue transcripts. Ontological evaluation in terms of subcellular targets identified gene products involved in mitochondrial processes are significantly suppressed, consistent with the well-established persistent mitochondrial dysfunction. Further classification of genes into biochemical networks revealed several pathways modulated by DOX, including glycolysis and fatty acid metabolism, supporting the notion that mitochondria are key targets in DOX toxicity. In conclusion, this comprehensive transcript profile provides important insights into critical targets and molecular adaptations that characterize the persistent cardiomyopathy associated with long-term exposure to DOX.

Late echocardiography assessment of systolic and diastolic function of the left ventricle in pediatric cancer survivors after anthracycline therapy

BACKGROUND

The usefulness of daunorubicin (DAUNO) and doxorubicin, members of the anthracycline class of anticancer drugs, is limited by their cardiotoxicity. The purpose of our echocardiographic study was to assess the left ventricular (LV) function in long-term pediatric cancer survivors who had received DAUNO and dox as part of their therapy.

PATIENTS AND METHODS

Seventy patients and 70 age, sex, and body surface area matched healthy controls were evaluated. Among the patients, the mean cumulative anthracycline dose was 321.6 (range, 150 to 868 mg/m); the mean interval from cancer diagnosis to evaluation was 13.9 years (range, 7 to 30 y).

RESULTS

Fifteen of the 70 (21.4%) patients had a reduced ejection fraction (EF). Compared with the healthy controls, the mean EF and E/A were decreased to low normal levels in the patients, whereas deceleration time and isovolumetric relaxation time were prolonged. The E/A and deceleration time were significantly different for the females but not the males. The Tissue Doppler Index was normal but the Myocardial Performance Index was prolonged and correlated with EF (r=-0.499, P<0.001). There was a correlation between EF with cumulative anthracycline dose (r=-0.306; P=0.010) and time off therapy (r=-0.281; P=0.019). Diastolic indices suggested a tendency toward abnormal LV relaxation. Myocardial Performance Index seems to be a good index for monitoring LV status, because it was prolonged as EF decreased.

CONCLUSIONS

This study suggests that long-term survivors who received doxorubicin and DAUNO may be found to have subclinical features of myocardial dysfunction when evaluated years after the completion of therapy.

Peroxisomal proliferator-activated receptor-alpha protects renal tubular cells from doxorubicin-induced apoptosis

Peroxisome proliferator-activated receptor-alpha (PPAR-alpha) is a transcription factor and has been reported to inhibit cisplatin-mediated proximal tubule cell death. In addition, doxorubicin (Adriamycin)-induced nephrosis in rats is a commonly used experimental model for pharmacological studies of human chronic renal diseases. In this study, we investigated the protective effect of PPAR-alpha on doxorubicin-induced apoptosis and its detailed mechanism in NRK-52E cells and animal models. The mRNA level of PPAR-alpha was found to be reduced by doxorubicin treatment in NRK-52E cells. PPAR-alpha overexpression in NRK-52E cells significantly inhibited doxorubicin-induced apoptosis and the quantity of cleaved caspase-3. Endogenous prostacyclin (PGI(2)) augmentation, which has been reported to protect NRK-52E cells from doxorubicin-induced apoptosis, induced the translocation and activation of PPAR-alpha. The transformation of PPAR-alpha short interfering RNA was applied to silence the PPAR-alpha gene, which abolished the protective effect of PGI(2) augmentation in doxorubicin-treated cells. To confirm the protective role of PPAR-alpha in vivo, PPAR-alpha activator docosahexaenoic acid (DHA) was administered to doxorubicin-treated mice, and it has been shown to significantly reduce the doxorubicin-induced apoptotic cells in renal cortex. However, this protective effect of DHA did not exist in PPAR-alpha-deficient mice. In NRK-52E cells, the overexpression of PPAR-alpha elevated the activity of catalase and superoxide dismutase and inhibited doxorubicin-induced reactive oxygen species (ROS). PPAR-alpha overexpression also inhibited the doxorubicin-induced activity of nuclear factor-kappaB (NF-kappaB), which was associated with the interaction between PPAR-alpha and NF-kappaB p65 subunit as revealed in immunoprecipitation assays. Therefore, PPAR-alpha is capable of inhibiting doxorubicin-induced ROS and NF-kappaB activity and protecting NRK-52E cells from doxorubicin-induced apoptosis.

Cytoprotective effect of anthocyanins against doxorubicin-induced toxicity in H9c2 cardiomyocytes in relation to their antioxidant activities

The effect of six anthocyanidins and seven anthocyanins against doxorubicin (Dox)-induced cardiotoxicity in relation to their antioxidant properties was investigated in H9c2 cardiomyocytes. The exposure to Dox, a highly effective cytotoxic agent against cancer cells, induced significant cell death, intracellular reactive oxygen species (ROS), and lipid peroxidation in non-tumorigenic cardiac cell culture. All anthocyanidins (50 and/or 100 microM) significantly increased cell survival up to 40% compared to the Dox-treated controls. Especially, cyanidin and delphinidin, which have an ortho-dihydroxyl moiety (3',4'-OH) on the flavylium skeleton, demonstrated the most potent protection against cytotoxicity (EC(50) of 113 and 179 microM, respectively) as well as lipid peroxidation induced by Dox treatment. In contrast, seven anthocyanins having a glycosidic moiety showed little effect in cytoprotection and lipid peroxidation, although they markedly blocked intracellular ROS generation. All anthocyanidins and anthocyanins had higher TEAC values than ascorbic acid, and efficaciously scavenged superoxide anion (O(2)(-)), hydrogen peroxide (H(2)O(2)), peroxynitrite (ONOO(-)) and nitric oxide (NO), but not hydroxyl radical (OH()). Their O(2)(-) scavenging activity was well correlated with the observed cytoprotection (r=0.67, p<0.05). These results suggest that anthocyanidins can ameliorate Dox-induced cardiotoxicity by, at least in part, scavenging of O(2)(-) generated by Dox.

Corticotropin-releasing factor family and its receptors: tumor therapeutic targets?

Urocortin (UCN) and corticotropin-releasing factor (CRF) are members of CRF family. Though CRF is mainly distributed in central nervous system (CNS), UCN has been reported to play biologically diverse roles in several systems such as cardiovascular, respiratory, digestive, reproductive, stress, immunologic system, etc. UCN and CRF bind to two known receptors, CRFR1 and CRFR2, to function. Both CRF receptors are distributed in CNS and periphery tissues, and their expression in cancer tissues has been reported. Now there are many documents indicating UCN/CRF play an important role in the regulation of carcinogenesis. There is also evidence indicating UCN/CRF have anticancer effects via CRFRs. This paper will review the effects of CRF family in cancers.