Daunorubicin-induced apoptosis in rat cardiac myocytes is inhibited by dexrazoxane

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

Evaluation of Ameliorative Effect of Quercetin and Candesartan in Doxorubicin-Induced Cardiotoxicity

BACKGROUND

Several mechanisms have been explored for the anthracycline myocardial toxicity. These are free-radical generation, myocyte apoptosis, lipid peroxidation, mitochondrial deterioration, and direct repression of muscle-specific gene expression. Adriamycin (Doxorubicin) is a potent anti-cancer agent. Adriamycin in prolonged use is fatal and generates free radicals that lead to dose-dependent cardiac toxicity.

OBJECTIVE

The intent of the study was to explore the protective activity of candesartan and quercetin in cardiomyopathy induced by doxorubicin in rats.

METHODS

To induce cardiac toxicity, rats were intraperitoneally treated with doxorubicin (06 equivalent injections of 2.5 mg/kg, i. p. at 48 hour interval for 02 consecutive weeks to achieve a cumulative dose of 15 mg/kg). Individual and combined oral treatment of candesartan (5 mg/kg/day) and quercetin (10 mg/kg/day) was administered for four weeks.

RESULTS

Following cardiomyopathy, heart/body weight ratio (3.526 × 10^-3), serum creatine kinase (352.4±16.99 IU/L), lactate dehydrogenase (661.7±20.45 IU/L) levels were elevated in addition to altered lipid profile (TC - 118.4±4.25 mg/dL, TG - 263.3±9.99 mg/dL, VLDL - 52.66±1.99 mg/dL, LDL - 52.99±5.80 mg/dL and HDL - 12.78±0.36 mg/dL). The pre-cotreatment of candesartan and quercetin significantly restored the values to normal. The increased level of lipid peroxides (33.12±1.63 µmol/mg protein), serum troponin-T (1.82 ± 0.11 pg/mL) and nitric oxide (13.33±0.73 nmol/mg protein) level along with attenuating antioxidant profile, ie catalase, glutathione and superoxide dismutase (1.43±0.12 nmol/mg protein, 8.48±0.42 nmol/mg protein and 2.09±0.031 U/mg protein) were reversed to normal. Morphometry and histopathologic changes represented a beneficial effect of single and combination pre-cotreatment of drugs which significantly decreases adriamycin cardiac toxicity.

CONCLUSION

The overall result depicts more beneficial and cardioprotective effect of quercetin and candesartan combination as compared to their individual effects in doxorubicin treated animals. Therefore, this combination might be a suitable option to treat the cardiotoxic effect of doxorubicin.

Exercise intervention decreases acute and late doxorubicin-induced cardiotoxicity

BACKGROUND

Doxorubicin (Dox) is one of the most effective chemotherapy agents used to treat adolescent and young adult sarcoma patients. Unfortunately, Dox causes cardiotoxicities that compromise long-term survival. We investigated whether exercise prevented cardiotoxicity and increased survival following myocardial infarction.

METHODS

Juvenile mice received Dox, Dox + exercise (Exer), Dox then exercise or were exercised during and after Dox. Mice were evaluated by echocardiography and histology immediately after therapy and 12 weeks later. Mice subjected to permanent ligation of the left anterior descending artery 90 days after therapy were assessed for survival at 45 and 100 days.

RESULTS

Mice treated with Dox, but not Dox + Exer, had decreased ejection fraction (EF) and fractional shortening (FS) immediately after Dox therapy, which continued to deteriorate over 12 weeks with the development of diastolic failure and fibrosis. Acute Dox-induced cardiotoxicity was documented by induction of autophagy and abnormal mitochondria and vascular architecture with decreased pericytes. These abnormalities persisted 12 weeks after therapy. These acute and late changes were not seen in the Dox + Exer group. Initiating exercise after Dox therapy promoted recovery of EF and FS with no functional or histologic evidence of Dox-induced damage 12 weeks after therapy. Survival rates at 100 days after MI were 67% for control mice, 22% for mice that received Dox alone, and 56% for mice that received Dox + Exer.

CONCLUSIONS

Exercise inhibited both early and late Dox-induced cardiotoxicity and increased recovery from an ischemic event. Exercise interventions have the potential to decrease Dox-induced cardiac morbidity.

Advances in the application of nanotechnology in reducing cardiotoxicity induced by cancer chemotherapy

Advances in the development of anti-tumour drugs and related technologies have resulted in a significant increase in the number of cancer survivors. However, the incidence of chemotherapy-induced cardiotoxicity (CIC) has been rising continuously, threatening their long-term survival. The integration of nanotechnology and biomedicine has brought about an unprecedented technological revolution and has promoted the progress of anti-tumour therapy. In this review, we summarised the possible mechanisms of CIC, evaluated the role of nanoparticles (including liposomes, polymeric micelles, dendrimers, and hydrogels) as drug carriers in preventing cardiotoxicity and proposed five advantages of nanotechnology in reducing cardiotoxicity: Liposomes cannot easily penetrate the heart's endothelial barrier; optimized delivery strategies reduce distribution in important organs, such as the heart; targeting the tumour microenvironment and niche; stimulus-responsive polymer nano-drug carriers rapidly iterate; better economic benefits were obtained. Nanoparticles can effectively deliver chemotherapeutic drugs to tumour tissues, while reducing the toxicity to heart tissues, and break through the dilemma of existing chemotherapy to a certain extent. It is important to explore the interactions between the physicochemical properties of nanoparticles and optimize the highly specific tumour targeting strategy in the future.

Tangeretin-Assisted Platinum Nanoparticles Enhance the Apoptotic Properties of Doxorubicin: Combination Therapy for Osteosarcoma Treatment

Osteosarcoma (OS) is the most common type of cancer and the most frequent malignant bone tumor in childhood and adolescence. Nanomedicine has become an indispensable field in biomedical and clinical research, with nanoparticles (NPs) promising to increase the therapeutic efficacy of anticancer drugs. Doxorubicin (DOX) is a commonly used chemotherapeutic drug against OS; however, it causes severe side effects that restrict its clinical applications. Here, we investigated whether combining platinum NPs (PtNPs) and DOX could increase their anticancer activity in human bone OS epithelial cells (U2OS). PtNPs with nontoxic, effective, thermally stable, and thermoplasmonic properties were synthesized and characterized using tangeretin. We examined the combined effects of PtNPs and DOX on cell viability, proliferation, and morphology, reactive oxygen species (ROS) generation, lipid peroxidation, nitric oxide, protein carbonyl content, antioxidants, mitochondrial membrane potential (MMP), adenosine tri phosphate (ATP) level, apoptotic and antiapoptotic gene expression, oxidative stress-induced DNA damage, and DNA repair genes. PtNPs and DOX significantly inhibited U2OS viability and proliferation in a dose-dependent manner, increasing lactate dehydrogenase leakage, ROS generation, and malondialdehyde, nitric oxide, and carbonylated protein levels. Mitochondrial dysfunction was confirmed by reduced MMP, decreased ATP levels, and upregulated apoptotic/downregulated antiapoptotic gene expression. Oxidative stress was a major cause of cytotoxicity and genotoxicity, confirmed by decreased levels of various antioxidants. Furthermore, PtNPs and DOX increased 8-oxo-dG and 8-oxo-G levels and induced DNA damage and repair gene expression. Combination of cisplatin and DOX potentially induce apoptosis comparable to PtNPs and DOX. To the best of our knowledge, this is the first report to describe the combined effects of PtNPs and DOX in OS.

Nucleolin protects against doxorubicin-induced cardiotoxicity via upregulating microRNA-21

Nucleolin is a multifunctional protein and participates in many important biological processes. Our previous study found that nucleolin protects the heart against myocardial ischemia-reperfusion injury. In this study, we aimed to investigate the role of nucleolin in doxorubicin (DOX)-induced cardiotoxicity. The expression pattern of nucleolin in hearts subjected to DOX injury was investigated, and we found that administration of DOX induced nucleolin expression significantly in vivo and in vitro. Gene transfection and RNA interference approaches were used in cardiomyocytes to investigate the function of nucleolin. Nucleolin overexpression protects cardiomyocytes against DOX-induced injury. Nucleolin-ablated cardiomyocytes become susceptible to the injury induced by DOX. The hearts of cardiac-myocyte-specific nucleolin transgenic mice are more resistant to DOX injury. Furthermore, nucleolin upregulates microRNA(miRNA)-21 expression in vivo and in vitro, and the miRNA-21 inhibitor negates the protective effect of nucleolin against injury induced by DOX. These results have demonstrated that nucleolin is involved in the regulation of DOX-induced cardiac injury and dysfunction via the regulation of miRNA-21 expression, and may be a novel therapeutic target for DOX-induced cardiotoxicity.

Simple discrimination of sub-cycling cells by propidium iodide flow cytometric assay in Jurkat cell samples with extensive DNA fragmentation

Human leukemia Jurkat T cells were analyzed for apoptosis and cell cycle by flow cytometry, using the Annexin V/propidium iodide (PI) standard assay, and a simple PI staining in Triton X-100/digitonin-enriched PI/RNase buffer, respectively. Cells treated with doxorubicin or menadione displayed a very strong correlation between the apoptotic cell fraction measured by the Annexin V/PI assay, and the weight of a secondary cell population that emerged on the forward scatter (FS)/PI plot, as well as on the side scatter (SS)/PI and FL1/PI plots generated from parallel cell cycle recordings. In both cases, the Pearson correlation coefficients were >0.99. In cell cycle determinations, PI fluorescence was detected on FL3 (620/30 nm), and control samples exhibited the expected linear dependence of FL3 on FL1 (525/40 nm) signals. However, increasing doses of doxorubicin or menadione generated a growing subpopulation of cells displaying a definite right-shift on the FS/FL3, SS/FL3 and FL1/FL3 plots, as well as decreased PI fluorescence, indicative of ongoing fragmentation and loss of nuclear DNA. By gating on these events, the resulting fraction of presumably sub-cycling cells (i.e. cells with cleaved DNA, counting sub-G0/G1, sub-S and sub-G2/M cells altogether) was closely similar to the apoptotic rate assessed by Annexin V/PI labeling. Taken together, these findings suggest a possible way to recognize the entire population of cells undergoing apoptotic DNA cleavage and simultaneously determine the cell cycle distribution of non-apoptotic cells in PI-labeled cell samples with various degrees of DNA fragmentation, using a simple and reproducible multiparametric analysis of flow cytometric recordings.

Protective effects of curcumin against doxorubicin-induced toxicity and resistance: A review

Doxorubicin (DOX)-induced toxicity and resistance are major obstacles in chemotherapeutic approaches. Despite effective in the treatment of numerous malignancies, some clinicians have voiced concern that DOX has the potential to cause debilitating consequences in organ tissues, especially the heart. The mechanisms of toxicity and resistance are respectively related to induction of reactive oxygen species (ROS) and up-regulation of ATP-binding cassette (ABC) transporter. Curcumin (CUR) with several biological and pharmacological properties is expected to restore DOX-mediated impairments to tissues. This review is intended to address the current knowledge on DOX adverse effects and CUR protective actions in the heart, kidneys, liver, brain, and reproductive organs. Coadministration of CUR and DOX is capable of ameliorating DOX toxicity pertained to antioxidant, apoptosis, autophagy, and mitochondrial permeability.

The Platinum(II) Complexes Induced Oxidative Stress of Isolated Rat Heart

Interest for the clinical application of transition metal complexes as chemotherapeutic agents initially started with discovery of cisplatin. Despite the remarkable clinical success, cisplatin treatment is limited due to its resistance and side effects. Over the last 40 years, numerous transition metal complexes were synthesized and investigated in vitro and in vivo in order to establish a metallopharmaceutical that will exert less toxicity and equal or higher potency. We have compared the cardiotoxicity of 2 platinum complexes, one ligand, and a starting salt for complex synthesis using an experimental model of an isolated, perfused rat heart according to the Langendorfftechnique. The cardiotoxicity was assessed by comparison of oxidative stress induced following the perfusion of the following compounds: Dichloro(1,2-diaminocyclohexane)platinum(II), cisplatin, potassium-tetra-chloroplatinum(II) and 1,2-diaminocyclohexane, which were perfused at increasing concentrations from 10−8 to 10−4 M for 30 minutes. The oxidative stress was assessed by determination of superoxide anion radical, hydrogen peroxide, thiobarbituric acid reactive substances, and nitric oxide from the coronary venous effluent. Our results showed that the levels of oxidative stress parameters were not significantly affected by perfusion with all the tested compounds and were not dose-dependent. These results could be of importance to further investigations concerning the effects of platinum-based potential anticancer drugs on the heart.

Long-term arterial complications of chemotherapy in patients with cancer

The number of cancer survivors has gradually increased in recent decades. However, the cancer survivors are at risk for conditions related to their initial disease and its treatment, i.e. surgery, systemic treatment or radiotherapy. Cardiovascular complications, such as myocardial infarction, are common side effects of these therapies. Cardiovascular damage can occur during treatment or month to years after the initial treatment, as late effect of the cancer treatment. The pathophysiology of these effects is not yet fully understood, but an important part of the cardiovascular complications are thought to be the result of effects of anticancer agents on the structural and functional properties of the endothelium. Because these conditions can result in a high degree of morbidity and mortality, understanding how to improve the prevention, recognition, and treatment of vascular disease is an important medical priority in the care for cancer survivors. This review will focus on the long-term arterial complications of chemotherapy in cancer survivors. It will summarize the epidemiology and pathophysiology of these complications. Furthermore, important long-term clinical conditions related to these effects will be outlined, including cardiovascular risk management in terms of prevention, evaluation and therapy.

Cardioprotective Effect of Grape Seed Extract on Chronic Doxorubicin-Induced Cardiac Toxicity in Wistar Rats

Purpose: The aim of the present study was to determine the ability of grape seed extract (GSE) as a powerful antioxidant in preventing adverse effect of doxorubicin (DOX) on heart function. Methods: Male rats were divided into three groups: control, DOX (2 mg/kg/48h, for 12 days) and GSE (100 mg/kg/24h, for 16 days) plus DOX. Left ventricular (LV) function and hemodynamic parameters were assessed using echocardiography, electrocardiography and a Millar pressure catheter. Histopathological analysis and in vitro antitumor activity were also evaluated. Results: DOX induced heart damage in rats through decreasing the left ventricular systolic and diastolic pressures, rate of rise/decrease of LV pressure, ejection fraction, fractional shortening and contractility index as demonstrated by echocardiography, electrocardiography and hemodynamic parameters relative to control group. Our data demonstrated that GSE treatment markedly attenuated DOX-induced toxicity, structural changes in myocardium and improved ventricular function. Additionally, GSE did not intervene with the antitumor effect of DOX. Conclusion: Collectively, the results suggest that GSE is potentially protective against DOX-induced toxicity in rat heart and maybe increase therapeutic index of DOX in human cancer treatment.

Salvianolic acid B protects against doxorubicin induced cardiac dysfunction via inhibition of ER stress mediated cardiomyocyte apoptosis

Salvia miltiorrhiza Bunge is a well-known medicinal plant in China. Salvianolic acid B (Sal B) is the most abundant bioactive compound extracted from the root of S. miltiorrhiza. The present study investigates the effect of Sal B on cardiac function and cardiomyocyte apoptosis in doxorubicin (DOX)-treated mice. After pretreatment with Sal B (2 mg kg-1 iv) for 7 d, male BALB/c mice were injected with a single dose of DOX (20 mg kg-1 ip). The cardioprotective effect of Sal B was observed on the 7th day after DOX treatment. DOX caused retarded body growth, apoptotic damage, and Bcl-2 expression disturbance. In contrast, Sal B pretreatment (2 mg kg-1 iv before DOX administration) attenuated the DOX induced apoptotic damage in heart tissues. Further study indicated that Sal B protected against DOX induced cardiotoxicity, at least, partially, by inhibiting endoplasmic reticulum stress, and by being involved in the PI3K/Akt pathway. These findings clarified the potential of Sal B as a promising reagent for treating DOX induced cardiotoxicity.

The TGF-β pathway mediates doxorubicin effects on cardiac endothelial cells

Elevated ALK4/5 ligands including TGF-β and activins have been linked to cardiovascular remodeling and heart failure. Doxorubicin (Dox) is commonly used as a model of cardiomyopathy, a condition that often precedes cardiovascular remodeling and heart failure. In 7-8-week-old C57Bl/6 male mice treated with Dox we found decreased capillary density, increased levels of ALK4/5 ligand and Smad2/3 transcripts, and increased expression of Smad2/3 transcriptional targets. Human cardiac microvascular endothelial cells (HCMVEC) treated with Dox also showed increased levels of ALK4/5 ligands, Smad2/3 transcriptional targets, a decrease in proliferation and suppression of vascular network formation in a HCMVEC and human cardiac fibroblasts co-culture assay. Our hypothesis is that the deleterious effects of Dox on endothelial cells are mediated in part by the activation of the TGF-β pathway. We used the inhibitor of ALK4/5 kinases SB431542 (SB) in concert with Dox to ascertain the role of TGF-β pathway activation in doxorubicin induced endothelial cell defects. SB prevented the suppression of HCMVEC proliferation in the presence of TGF-β2 and activin A, and alleviated the inhibition of HCMVEC proliferation by Dox. SB also prevented the suppression of vascular network formation in co-cultures of HCMVEC and human cardiac fibroblasts treated with Dox. Our results show that the inhibition of the TGF-β pathway alleviates the detrimental effects of Dox on endothelial cells in vitro.

Analysis of redox and apoptotic effects of anthracyclines to delineate a cardioprotective strategy

PURPOSE

Cardiotoxic side effects of anthracyclines limit their use as effective chemotherapeutics. One mechanistic model of anthracycline-induced cardiotoxicity is attributed to the generation of intracellular reactive oxygen species (ROS). However, this theory has been questioned because several cardioprotective strategies have included the use of antioxidants without significant clinical benefit. We sought to determine whether measurement of intracellular reactive oxygen species after anthracycline exposure in vivo and in vitro could provide a means for designing more effective antioxidant-based cardioprotective schemes.

METHODS

Intracellular levels of ROS were assessed in peripheral blood mononuclear cells from leukemia bearing mice exposed to anthracyclines and in patients receiving anthracyclines. Comparison of cell death induction and ROS levels were also conducted in vitro in cardiomyocyte and leukemia lines. ROS blockade using antioxidants was conducted, and effects on cell death were assessed.

RESULTS

Elevated ROS in blood of mice and representative patient samples correlated with cardiomyocyte necrosis and decreased ejection fraction. In vitro, comparison of the cytotoxic effects of anthracyclines in acute leukemia cells and in cardiomyocytes revealed distinct kinetics of cell death induction and dependence upon oxidative stress. Although apoptotic cell death was observed in both acute leukemia cells and cardiomyocytes, the antioxidant N-acetylcysteine protected cardiomyocytes but not acute leukemia cells from anthracycline cytotoxicity.

CONCLUSIONS

Our findings point toward revisiting the use of NAC as a cardioprotective agent since it does not appear to interfere with the cytotoxic action of anthracyclines. NAC has been evaluated clinically for cardioprotective activity but future trials must ensure that adequate dose, scheduling and incorporation of markers of oxidative stress are included.

Tumor-targeted and pH-controlled delivery of doxorubicin using gold nanorods for lung cancer therapy

Background

In lung cancer, the efficacy of conventional chemotherapy is limited due to poor drug accumulation in tumors and nonspecific cytotoxicity. Resolving these issues will increase therapeutic efficacy.

Methods

GNR-Dox-Tf-NPs (gold nanorod-doxorubicin-transferrin-nanoparticles) were prepared by different chemical approaches. The efficacy of these nanoparticles was carried out by cell viability in lung cancer and primary coronary artery smooth muscle cells. The receptor-mediated endocytosis studies were done with human transferrin and desferrioxamine preincubation. The GNR-Dox-Tf nanoparticles induced apoptosis, and DNA damage studies were done by Western blot, H2AX foci, and comet assay.

Results

We developed and tested a gold nanorod-based multifunctional nanoparticle system (GNR-Dox-Tf-NP) that carries Dox conjugated to a pH-sensitive linker and is targeted to the transferrin receptor overexpressed in human lung cancer (A549, HCC827) cells. GNR-Dox-Tf-NP underwent physicochemical characterization, specificity assays, tumor uptake studies, and hyperspectral imaging. Biological studies demonstrated that transferrin receptor-mediated uptake of the GNR-Dox-Tf-NP by A549 and HCC827 cells produced increased DNA damage, apoptosis, and cell killing compared with nontargeted GNR-Dox-NP. GNR-Dox-Tf-NP-mediated cytotoxicity was greater (48% A549, 46% HCC827) than GNR-Dox-NP-mediated cytotoxicity (36% A549, 39% HCC827). Further, GNR-Dox-Tf-NP markedly reduced cytotoxicity in normal human coronary artery smooth muscle cells compared with free Dox.

Conclusion

Thus, GNR-Dox-Tf nanoparticles can selectively target and deliver Dox to lung tumor cells and alleviate free Dox-mediated toxicity to normal cells.

Sulforaphane protects the heart from doxorubicin-induced toxicity

Cardiotoxicity is one of the major side effects encountered during cancer chemotherapy with doxorubicin (DOX) and other anthracyclines. Previous studies have shown that oxidative stress caused by DOX is one of the primary mechanisms for its toxic effects on the heart. Since the redox-sensitive transcription factor, Nrf2, plays a major role in protecting cells from the toxic metabolites generated during oxidative stress, we examined the effects of the phytochemical sulforaphane (SFN), a potent Nrf2-activating agent, on DOX-induced cardiotoxicity. These studies were carried out both in vitro and in vivo using rat H9c2 cardiomyoblast cells and wild type 129/sv mice, and involved SFN pretreatment followed by SFN administration during DOX exposure. SFN treatment protected H9c2 cells from DOX cytotoxicity and also resulted in restored cardiac function and a significant reduction in DOX-induced cardiomyopathy and mortality in mice. Specificity of SFN induction of Nrf2 and protection of H9c2 cells was demonstrated in Nrf2 knockdown experiments. Cardiac accumulation of 4-hydroxynonenal (4-HNE) protein adducts, due to lipid peroxidation following DOX-induced oxidative stress, was significantly attenuated by SFN treatment. The respiratory function of cardiac mitochondria isolated from mice exposed to DOX alone was repressed, while SFN treatment with DOX significantly elevated mitochondrial respiratory complex activities. Co-administration of SFN reversed the DOX-associated reduction in nuclear Nrf2 binding activity and restored cardiac expression of Nrf2-regulated genes at both the RNA and protein levels. Together, our results demonstrate for the first time that the Nrf2 inducer, SFN, has the potential to provide protection against DOX-mediated cardiotoxicity.

Sulforaphane prevents doxorubicin-induced oxidative stress and cell death in rat H9c2 cells

Sulforaphane, a natural isothiocyanate compound found in cruciferous vegetables, has been shown to exert cardioprotective effects during ischemic heart injury. However, the effects of sulforaphane on cardiotoxicity induced by doxorubicin are unknown. Thus, in the present study, H9c2 rat myoblasts were pre-treated with sulforaphane and its effects on cardiotoxicity were then examined. The results revealed that the pre-treatment of H9c2 rat myoblasts with sulforaphane decreased the apoptotic cell number (as shown by trypan blue exclusion assay) and the expression of pro-apoptotic proteins (Bax, caspase-3 and cytochrome c; as shown by western blot analysis and immunostaining), as well as the doxorubicin-induced increase in mitochondrial membrane potential (measured by JC-1 assay). Furthermore, sulforaphane increased the mRNA and protein expression of heme oxygenase-1 (HO-1, measured by RT-qPCR), which consequently reduced the levels of reactive oxygen species (ROS, measured using MitoSOX Red reagent) in the mitochondria which were induced by doxorubicin. The cardioprotective effects of sulforaphane were found to be mediated by the activation of the Kelch-like ECH-associated protein 1 (Keap1)/NF-E2-related factor-2 (Nrf2)/antioxidant-responsive element (ARE) pathway, which in turn mediates the induction of HO-1. Taken together, the findings of this study demonstrate that sulforaphane prevents doxorubicin-induced oxidative stress and cell death in H9c2 cells through the induction of HO-1 expression.

Total Flavonoids from Clinopodium chinense (Benth.) O. Ktze Protect against Doxorubicin-Induced Cardiotoxicity In Vitro and In Vivo

Doxorubicin has cardiotoxic effects that limit its clinical benefit in cancer patients. This study aims to investigate the protective effects of the total flavonoids from Clinopodium chinense (Benth.) O. Ktze (TFCC) against doxorubicin- (DOX-) induced cardiotoxicity. Male rats were intraperitoneally injected with a single dose of DOX (3 mg/kg) every 2 days for three injections. Heart samples were collected 2 weeks after the last DOX dose and then analyzed. DOX delayed body and heart growth and caused cardiac tissue injury, oxidative stress, apoptotic damage, mitochondrial dysfunction, and Bcl-2 expression disturbance. Similar experiments in H9C2 cardiomyocytes showed that doxorubicin reduced cell viability, increased ROS generation and DNA fragmentation, disrupted mitochondrial membrane potential, and induced apoptotic cell death. However, TFCC pretreatment suppressed all of these adverse effects of doxorubicin. Signal transduction studies indicated that TFCC suppressed DOX-induced overexpression of p53 and phosphorylation of JNK, p38, and ERK. Studies with LY294002 (a PI3K/AKT inhibitor) demonstrated that the mechanism of TFCC-induced cardioprotection also involves activation of PI3K/AKT. These findings indicated the potential clinical application of TFCC in preventing DOX-induced cardiac oxidative stress.

The role of TNF-α, Fas/Fas ligand system and NT-proBNP in the early detection of asymptomatic left ventricular dysfunction in cancer patients treated with anthracyclines

Background

Anthracycline-induced cardiotoxicity typically presents as congestive heart failure (CHF). As immuno-inflammatory activation and apoptosis are important mechanisms in the process of heart failure, the use of biomarkers that could detect cardiovascular toxicity before the clinical presentation is of great importance. We studied whether sTNF-a, sTNF-RI, sTNF-RII, Fas/FasLigand system and NT-proBNP associate with early cardiac dysfunction in patients receiving cardiotoxic drugs.

Methods

Two groups of breast cancer patients—group A with metastatic disease under chemotherapy with epirubicin and group B with no residual disease under a less cardiotoxic regimen—as well as healthy women were included in this prosprective study. NT-proBNP, sTNF-a, sTNF-RI, sTNF-RII, sFas, sFas-Ligand and left ventricular ejection fraction (LVEF) were determined in all patients before and after the completion of chemotherapy.

Results

In Group A, an increase in sFas levels (p < 0.001), a decrease in the sFasL levels (p = 0.010), an NT-proBNP increase (p < 0.001) and a significant reduction of LVEF (p < 0.001) was recorded post-chemotherapy. The decrease in LVEF correlated significantly with the increase in sFas, the decrease in sFasL and the rise in NT-proBNP levels. In Group B, TNF-RI levels were higher (p = 0.024) and mean sFas-L levels lower (p = 0.021) post chemotherapy with no LVEF drop. Two of group A (7.6%) patients developed symptomatic CHF 12 and 14 months respectively after the end of chemotherapy.

Conclusion

SFas, sFas-L and NT-proBNP correlate with reductions in LVEF and could be used as sensitive biochemical indices for the detection of asymptomatic left ventricular dysfunction in cancer patients under cardiotoxic chemotherapy.

A systematic review of the pathophysiology of 5-fluorouracil-induced cardiotoxicity

Background

Cardiotoxicity is a serious side effect to treatment with 5-fluorouracil (5-FU), but the underlying mechanisms are not fully understood. The objective of this systematic review was to evaluate the pathophysiology of 5-FU- induced cardiotoxicity.

Methods

We systematically searched PubMed for articles in English using the search terms: 5-FU OR 5-fluorouracil OR capecitabine AND cardiotoxicity. Papers evaluating the pathophysiology of this cardiotoxicity were included.

Results

We identified 27 articles of 26 studies concerning the pathophysiology of 5-FU-induced cardiotoxicity. The studies demonstrated 5-FU-induced: hemorrhagic infarction, interstitial fibrosis and inflammatory reaction in the myocardium; damage of the arterial endothelium followed by platelet aggregation; increased myocardial energy metabolism and depletion of high energy phosphate compounds; increased superoxide anion levels and a reduced antioxidant capacity; vasoconstriction of arteries; changes in red blood cell (RBC) structure, function and metabolism; alterations in plasma levels of substances involved in coagulation and fibrinolysis and increased endothelin-1 levels and N-terminal-pro brain natriuretic peptide levels. Based on these findings the proposed mechanisms are: endothelial injury followed by thrombosis, increased metabolism leading to energy depletion and ischemia, oxidative stress causing cellular damage, coronary artery spasm leading to myocardial ischemia and diminished ability of RBCs to transfer oxygen resulting in myocardial ischemia.

Conclusions

There is no evidence for a single mechanism responsible for 5-FU-induced cardiotoxicity, and the underlying mechanisms might be multifactorial. Further research is needed to elucidate the pathogenesis of this side effect.

Glucocorticoid induced leucine zipper inhibits apoptosis of cardiomyocytes by doxorubicin

Doxorubicin (Dox) is an indispensable chemotherapeutic agent for the treatment of various forms of neoplasia such as lung, breast, ovarian, and bladder cancers. Cardiotoxicity is a major concern for patients receiving Dox therapy. Previous work from our laboratory indicated that glucocorticoids (GCs) alleviate Dox-induced apoptosis in cardiomyocytes. Here we have found glucocorticoid-induced leucine zipper (GILZ) to be a mediator of GC-induced cytoprotection. GILZ was found to be induced in cardiomyocytes by GC treatment. Knocking down of GILZ using siRNA resulted in cancelation of GC-induced cytoprotection against apoptosis by Dox treatment. Overexpressing GILZ by transfection was able to protect cells from apoptosis induced by Dox as measured by caspase activation, Annexin V binding and morphologic changes. Western blot analyses indicate that GILZ overexpression prevented cytochrome c release from mitochondria and cleavage of caspase-3. When bcl-2 family proteins were examined, we found that GILZ overexpression causes induction of the pro-survival protein Bcl-xL. Since siRNA against Bcl-xL reverses GC induced cytoprotection, Bcl-xL induction represents an important event in GILZ-induced cytoprotection. Our data suggest that GILZ functions as a cytoprotective gene in cardiomyocytes.

Mitochondrial translocator protein (TSPO) ligands prevent doxorubicin-induced mechanical dysfunction and cell death in isolated cardiomyocytes

Contractile dysfunction and subsequent development of cardiomyopathies are well known limiting factors in the treatment of cancer with doxorubicin and have been linked to mitochondrial dysfunction. Here, using adult isolated paced cardiomyocytes, we have demonstrated that ligands of translocator protein (TSPO) 4'-chlorodiazepam and TRO40303 prevented the doxorubicin-induced alterations in contractility and improved cardiomyocyte viability. This cardioprotective effect was closely associated with both a potent reduction in reactive oxygen species production and inhibition of mitochondrial permeability transition pore opening. Thus, preventive administration of TSPO ligands may represent a novel pharmacological strategy to protect the heart during doxorubicin treatment.

Cardioprotective effects of fish omega-3 fatty acids on doxorubicin-induced cardiotoxicity in rats

The aim of this study was to investigate the protective effects of fish omega-3 (n-3) fatty acids on doxorubicin (DOX)-induced acute cardiotoxicity. A total of 24 rats were divided into three groups: control, DOX-treated, and DOX treated with fish n-3 fatty acids. Control group received 0.4 ml/kg/day of saline intragastrically. The rats in the fish n-3 fatty acid-pretreated group were given 400 mg/kg/day fish n-3 fatty acids for 30 days by intragastric intubation. To induce acute cardiotoxicity, DOX (30 mg/kg) was injected intraperitoneally by a single dose and the rats were killed after 48 h. DOX treatment caused severe damage in heart tissues. Disorganization of myocardial muscle fibers, myofibrillar loss, and cardiotoxic myocardial fibers with cytoplasmic vacuoles were seen. Fish n-3 fatty acid-treated rats showed an improved histological appearance in the DOX-treated group. Our data indicate a significant reduction in the activity of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling in cardiomyocytes of the DOX-treated group with fish n-3 fatty acids therapy. The DOX-treated with fish n-3 fatty acids group showed a significant decrease in malondialdehyde levels, and an increase in superoxide dismutase and glutathione peroxidase activities in comparison with the DOX-treated group. This study showed that fish n-3 fatty acids may be a suitable cardioprotector against acute toxic effects of DOX.

Rodent models of heart failure: an updated review

Heart failure (HF) is one of the major health and economic burdens worldwide, and its prevalence is continuously increasing. The study of HF requires reliable animal models to study the chronic changes and pharmacologic interventions in myocardial structure and function and to follow its progression toward HF. Indeed, during the past 40 years, basic and translational scientists have used small animal models to understand the pathophysiology of HF and find more efficient ways of preventing and managing patients suffering from congestive HF (CHF). Each species and each animal model has advantages and disadvantages, and the choice of one model over another should take them into account for a good experimental design. The aim of this review is to describe and highlight the advantages and drawbacks of some commonly used HF rodents models, including both non-genetically and genetically engineered models, with a specific subchapter concerning diastolic HF models.

Early and delayed cardioprotective intervention with dexrazoxane each show different potential for prevention of chronic anthracycline cardiotoxicity in rabbits

Despite incomplete understanding to its mechanism of action, dexrazoxane (DEX) is still the only clearly effective cardioprotectant against chronic anthracycline (ANT) cardiotoxicity. However, its clinical use is currently restricted to patients exceeding significant ANT cumulative dose (300mg/m(2)), although each ANT cycle may induce certain potentially irreversible myocardial damage. Therefore, the aim of this study was to compare early and delayed DEX intervention against chronic ANT cardiotoxicity and study the molecular events involved. The cardiotoxicity was induced in rabbits with daunorubicin (DAU; 3mg/kg/week for 10 weeks); DEX (60mg/kg) was administered either before the 1st or 7th DAU dose (i.e. after ≈300mg/m(2) cumulative dose). While both DEX administration schedules prevented DAU-induced premature deaths and severe congestive heart failure, only the early intervention completely prevented the left ventricular dysfunction, myocardial morphological changes and mitochondrial damage. Further molecular analyses did not support the assumption that DEX cardioprotection is based and directly proportional to protection from DAU-induced oxidative damage and/or deletions in mtDNA. Nevertheless, DAU induced significant up-regulation of heme oxygenase 1 pathway while heme synthesis was inversely regulated and both changes were schedule-of-administration preventable by DEX. Early and delayed DEX interventions also differed in ability to prevent DAU-induced down-regulation of expression of mitochondrial proteins encoded by both nuclear and mitochondrial genome. Hence, the present functional, morphological as well as the molecular data highlights the enormous cardioprotective effects of DEX and provides novel insights into the molecular events involved. Furthermore, the data suggests that currently recommended delayed intervention may not be able to take advantage of the full cardioprotective potential of the drug.

Daunomycin, an antitumor DNA intercalator, influences histone-DNA interactions

Although daunomycin and adriamycin are considered effective antitumor drugs and have been used in the clinic for over 40 years, their mechanism of action is still a matter of debate. We investigated the influence of daunomycin on interaction between linker or core histones and DNA in live HeLa cells in vitro, using image and flow cytometry. Exposure to daunomycin at clinically relevant concentrations (25-250 nM) caused dissociation of wild-type H1.1 as well as 4 H1 point mutants from DNA, followed by their accumulation in nucleoli and aggregation of chromatin. A detectable dissociation of H2B core histones occurred only at much higher concentrations of the drug (500 nM). Replication of DNA and synthesis of RNA were not halted by daunomycin (up to 2500 nM); however the characteristic subnuclear distribution of sites of transcription and replication was lost. Dissociation of the H1.1 linker histones and subsequent loss of higher order chromatin structures may constitute an important component of the mechanism of cytotoxicity of daunomycin.

Oxidative stress, redox signaling, and metal chelation in anthracycline cardiotoxicity and pharmacological cardioprotection

SIGNIFICANCE

Anthracyclines (doxorubicin, daunorubicin, or epirubicin) rank among the most effective anticancer drugs, but their clinical usefulness is hampered by the risk of cardiotoxicity. The most feared are the chronic forms of cardiotoxicity, characterized by irreversible cardiac damage and congestive heart failure. Although the pathogenesis of anthracycline cardiotoxicity seems to be complex, the pivotal role has been traditionally attributed to the iron-mediated formation of reactive oxygen species (ROS). In clinics, the bisdioxopiperazine agent dexrazoxane (ICRF-187) reduces the risk of anthracycline cardiotoxicity without a significant effect on response to chemotherapy. The prevailing concept describes dexrazoxane as a prodrug undergoing bioactivation to an iron-chelating agent ADR-925, which may inhibit anthracycline-induced ROS formation and oxidative damage to cardiomyocytes.

RECENT ADVANCES

A considerable body of evidence points to mitochondria as the key targets for anthracycline cardiotoxicity, and therefore it could be also crucial for effective cardioprotection. Numerous antioxidants and several iron chelators have been tested in vitro and in vivo with variable outcomes. None of these compounds have matched or even surpassed the effectiveness of dexrazoxane in chronic anthracycline cardiotoxicity settings, despite being stronger chelators and/or antioxidants.

CRITICAL ISSUES

The interpretation of many findings is complicated by the heterogeneity of experimental models and frequent employment of acute high-dose treatments with limited translatability to clinical practice.

FUTURE DIRECTIONS

Dexrazoxane may be the key to the enigma of anthracycline cardiotoxicity, and therefore it warrants further investigation, including the search for alternative/complementary modes of cardioprotective action beyond simple iron chelation.

Cardiac side effects of anticancer treatments: new mechanistic insights

Damage to heart cells leading to heart failure is a known complication of well-established cancer therapies including anthracycline antibiotics and radiation therapy, and the cardiovascular complications of these therapies has been controlled in large part through dose limitations and modifications of delivery methods. Recent research into the cellular and molecular mechanisms for the cardiovascular effects of these therapies may lead to other cardioprotective strategies that improve effectiveness of cancer treatments. Newer cancer therapies that have been developed based upon specifically targeting oncogene signaling also have been associated with heart failure. Rapid development of a detailed understanding of how these agents cause cardiac dysfunction promises to improve outcomes in cancer patients, as well as stimulate concepts of cardiovascular homeostasis that will likely accelerate development of cardiovascular therapies.

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.

Overexpression of Nrdp1 in the heart exacerbates doxorubicin-induced cardiac dysfunction in mice

Background

Cardiac cell death and generation of oxidative stress contribute to doxorubicin (DOX)-induced cardiac dysfunction. E3 ligase Nrdp1 plays a critical role in the regulation of cell apoptosis, inflammation and production of reactive oxygen species (ROS), which may contribute to heart failure. However, the role of Nrdp1 in DOX-induced cardiac injury remains to be determined.

Methods and Results

We examined the effect of Nrdp1 overexpression with DOX treatment in rat neonatal cardiomyocytes and mouse heart tissue. Cardiomyocytes were infected with adenovirus containing GFP (Ad-GFP), Nrdp1 wild-type (Ad-Nrdp1) or the dominant-negative form of Nrdp1 (Ad-Dn-Nrdp1), then treated with DOX for 24 hr. DOX treatment increased cell death and apoptosis, with Ad-Nrdp1 infection enhancing these actions but Ad-Dn-Nrdp1 infection attenuating these effects. Furthermore, 5 days after a single injection of DOX (20 mg/kg, intraperitoneally), Nrdp1 transgenic mice (TG) showed decreased cardiac function and increased apoptosis, autophagy and oxidative stress as compared with wild-type (WT) mice (P<0.01). Survival rate was significantly lower in Nrdp1 TG mice than in WT mice 10 days after DOX injection (P<0.01).

Conclusions/Significance

These results were associated with decreased activation of Akt, extracellular signal-regulated kinase 1/2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3) signaling pathways. Nrdp1 may be a key mediator in the development of cardiac dysfunction after DOX treatment and associated with inhibition of Akt, ERK1/2 and STAT3. Nrdp1 may be a new therapeutic target in protecting against the cardiotoxic effects of DOX.

Mechanisms of anthracycline cardiotoxicity and strategies to decrease cardiac damage

Anthracyclines are common chemotherapeutic agents used to treat many different types of cancer. Unfortunately, the use of anthracyclines is limited by their cardiotoxic effects, which may become manifest as late as 20 years from initial exposure. Studies in cells and animals suggest that the mechanism of anthracycline-induced cardiotoxicity (AIC) is multifactorial. Anthracyclines induce multiple forms of cellular injury by free radical production. In addition, anthracyclines alter nucleic acid biology by intercalation into DNA and modulate intracellular signaling, leading to cell death and the disruption of homeostatic processes such as sarcomere maintenance. In an effort to decrease AIC, many strategies have been tested, but no specific therapies are universally acknowledged to prevent or treat anthracycline-induced cardiac dysfunction. Newer imaging modalities and cardiac biomarkers may be useful in improving early detection of cardiac injury and dysfunction. As long as there is no cardiac-specific therapy for AIC, evidence suggests that high-risk patients will benefit from prophylactic treatment with neurohormonal blockade by angiotensin-converting enzyme inhibitors and beta-adrenergic receptor blockers.

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.

Beneficial effects of carbon monoxide-releasing molecule-2 (CORM-2) on acute doxorubicin cardiotoxicity in mice: role of oxidative stress and apoptosis

Doxorubicin (DXR) has been used in variety of human malignancies for decades. Despite its efficacy in cancer, clinical usage is limited because of its cardiotoxicity, which has been associated with oxidative stress and apoptosis. Carbon monoxide-releasing molecules (CORMs) have been shown to reduce the oxidative damage and apoptosis. The present study investigated the effects of CORM-2, a fast CO-releaser, against DXR-induced cardiotoxicity in mice using biochemical, histopathological and gene expression approaches. CORM-2 (3, 10 and 30 mg/kg/day) was administered intraperitoneally (i.p.) for 10 days and terminated the study on day 11. DXR (20 mg/kg, i.p.) was injected before 72 h of termination. Mice treated with DXR showed cardiotoxicity as evidenced by elevation of serum creatine kinase (CK) and lactate dehydrogenase (LDH), tissue malondialdehyde (MDA), caspase-3 and decrease the level of total antioxidant status (TAS) in heart tissues. Pre- and post-treatment with CORM-2 (30 mg/kg, i.p.) elicited significant improvement in CK, LDH, MDA, caspase-3 and TAS levels. Histopathological studies showed that cardiac damage with DXR has been reversed with CORM-2+DXR treatment. There was dramatic decrease in hematological count in DXR-treated mice, which has been improved with CORM-2. Furthermore, there was also elevation of mRNA expression of heme oxygenase-1, hypoxia inducible factor-1 alpha, vascular endothelial growth factor and decrease in inducible-nitric oxide synthase expression upon treatment with CORM-2 that might be linked to cardioprotection. These data suggest that CORM-2 treatment provides cardioprotection against acute doxorubicin-induced cardiotoxicity in mice and this effect may be attributed to CORM-2-mediated antioxidant and anti-apoptotic properties.

Safety of concurrent administration of dexrazoxane and doxorubicin in the canine cancer patient

Doxorubicin may cause a rare but serious cardiotoxicity. Dexrazoxane is a cardioprotectant drug used to reduce the risk of cardiotoxicity in human patients. In this study, 25 tumour-bearing dogs were treated with concurrent doxorubicin and dexrazoxane. The total number of doses of dexrazoxane given was 54 (range 1-5 doses per dog, median 2 doses). Five dogs received more than 165 mg m(2) cumulative doxorubicin dose before starting dexrazoxane. Haematologic, gastrointestinal and cardiovascular toxicities were considered tolerable. The combination of doxorubicin with dexrazoxane was well tolerated with minimal side-effects in this patient cohort. Future studies are required to evaluate potential cardioprotective effects of dexrazoxane given concurrently with doxorubicin.

Cancer therapy-associated cardiotoxicity and signaling in the myocardium

The cardiotoxic potential of cytotoxic cancer chemotherapy is well known. Prime examples are the anthracyclines, which are highly efficacious agents for hemopoietic malignancies and solid tumors, but their clinical use is limited primarily by cardiotoxicity. Besides the conventional chemotherapeutics, new cancer drugs were developed in the last decade with the goal to specifically inhibit selected molecular targets such as growth factor receptors or intracellular tyrosine kinases in cancer cells. However, the outcome of combining conventional and newer cancer therapies could have unexpected side effects not anticipated so far and the long-term outcome is not known. Sometimes, however, unexpected side effects also shed light on previously unknown physiological functions. For example, the anti-HER2 cancer therapeutic trastuzumab (Herceptin), which can induce cardiac dysfunction, has demonstrated the importance of the ErbB/neuregulin signaling system in the adult heart. Subsequently, the role of endothelial-myocardial communication in maintaining phenotype and survival of adult cardiomyocytes has increasingly been recognized.