A comparative study between catalase gene therapy and the cardioprotector monohydroxyethylrutoside (MonoHER) in protecting against doxorubicin-induced cardiotoxicity in vitro

Cardiotoxicity of chloroquine and hydroxychloroquine through mitochondrial pathway

BACKGROUND

Medical therapies can cause cardiotoxicity. Chloroquine (QC) and hydroxychloroquine (HQC) are drugs used in the treatment of malaria and skin and rheumatic disorders. These drugs were considered to help treatment of coronavirus disease (COVID-19) in 2019. Despite the low cost and availability of QC and HQC, reports indicate that this class of drugs can cause cardiotoxicity. The mechanism of this event is not well known, but evidence shows that QC and HQC can cause cardiotoxicity by affecting mitochondria and lysosomes.

METHODS

Therefore, our study was designed to investigate the effects of QC and HQC on heart mitochondria. In order to achieve this aim, mitochondrial function, reactive oxygen species (ROS) level, mitochondrial membrane disruption, and cytochrome c release in heart mitochondria were evaluated. Statistical significance was determined using the one-way and two-way analysis of variance (ANOVA) followed by post hoc Tukey to evaluate mitochondrial succinate dehydrogenase (SDH) activity and cytochrome c release, and Bonferroni test to evaluate the ROS level, mitochondrial membrane potential (MMP) collapse, and mitochondrial swelling.

RESULTS

Based on ANOVA analysis (one-way), the results of mitochondrial SDH activity showed that the IC₅₀ concentration for CQ is 20 µM and for HCQ is 50 µM. Based on two-way ANOVA analysis, the highest effect of CQ and HCQ on the generation of ROS, collapse in the MMP, and mitochondrial swelling were observed at 40 µM and 100 µM concentrations, respectively (p < 0.05). Also, the highest effect of these two drugs has been observed in 60 min (p < 0.05). The statistical results showed that compared to CQ, HCQ is able to cause the release of cytochrome c from mitochondria in all applied concentrations (p < 0.05).

CONCLUSIONS

The results suggest that QC and HQC can cause cardiotoxicity which can lead to heart disorders through oxidative stress and disfunction of heart mitochondria.

Restoring strategy of ethanolic extract of Moringa oleifera leaves against Tilmicosin-induced cardiac injury in rats: Targeting cell apoptosis-mediated pathways

Tilmicosin (Til), an effective macrolide antibiotic, is widely used against respiratory diseases in livestock; however, its treatment is associated with cardiac tissue impairments. In this study, the ethanolic extract of Moringa oleifera (MO) leaves was investigated at two doses (400 and 800 mg/kg body weight [bw], orally) to determine its role in counteracting the effects of Til treatment (75 mg/kg bw) on the cardiac tissue in rats, exploring the oxidative stress-mediated damage and apoptosis. A high dose of MO ethanolic extract elicits considerable changes in the body weight, reduces the mortality rate, neutralizes the impaired cardiac injury markers, improves antioxidant endpoints (total antioxidant capacity, superoxide dismutase, catalase activity, and reduced glutathione level). Also it attenuates the oxidative stress indices (total reactive oxygen species, 8-hydroxy-2-deoxyguanosine, lipid peroxides [malondialdehyde], and protein carbonyl levels) that are associated with Til injection. The co-administration of MO ethanolic extract with Til considerably modulates the expression of apoptosis pathway-encoding genes (Bcl-2, caspase-3, Bax, p53, apoptosis-inducing factor, and Apaf-1), particularly in the high-dose group. Our results support that the concurrent administration of MO ethanolic extract with Til at a dose of 800 mg/kg bw increases the protective activity of the antioxidant system and delays or slows the pathological development of cardiotoxicity mediated by Til injection.

Inflammatory and oxidative injury is induced in cardiac and pulmonary tissue following fipronil exposure in Japanese quail: mRNA expression of the genes encoding interleukin 6, nuclear factor kappa B, and tumor necrosis factor-alpha

The phenylpyrazole insecticide, fipronil, isused for the eradication of insects in agriculture, which also exposes various non-target groups such as birds and animals. Our aim was to assess the cardiac and pulmonary consequences of sub-acute administration of fipronil (¹∕₅ LD₅₀; 2.26 mg/kg) in the Japanese quail for fifteen days and to determine the tissue recovery over a period of 60 days. Fipronil exposure led to a significant decrease in the body weight of the treated birds. Its exposure also induced cardiac and pulmonary damage of varying degrees. Fipronil increased the lipid peroxide (LPO) and nitric oxide (NO) contents as well as indices of tissue injury in the serum of exposed birds. Furthermore, it decreased the antioxidant indices in both the organs. Most of these changes gradually reversed and the histological changes, particularly of the heart, reversed completely by day-60 of recovery. Furthermore, alterations in the mRNA gene expressions of Nuclear factor kappa B (NF-κB), Interleukin 6 (IL-6), and Tumor necrosis factor-alpha (TNF-α) were monitored by quantitative polymerase chain reaction (RT-PCR). In both the tissues, a significant up-regulation of the transcripts was recorded after fipronil administration, which was reversed during the recovery period in the heart tissue except for TNF-α, while the transcripts in the lung tissue declined non-significantly. This study showed that the exposure of Japanese quail to fipronil has a profound negative impact on heart and lung including oxidative injury and tissue inflammation. Fipronil can induce the activity of NF-κB inflammatory -signaling pathway that play a role in the associated tissue inflammation. Although most of the cardiac changes could be reversed after a recovery period of sixty days, the pulmonary changes did not reverse much.

Aspalathin, a dihydrochalcone C-glucoside, protects H9c2 cardiomyocytes against high glucose induced shifts in substrate preference and apoptosis

SCOPE

Energy deprivation in the myocardium is associated with impaired heart function. This study aims to investigate if aspalathin (ASP) can ameliorate hyperglycemic-induced shift in substrate preference and protect the myocardium against cell apoptosis.

METHODS AND RESULTS

H9c2 cells were exposed to, either normal (5.5 mM) or high (33 mM) glucose concentrations for 48 h. Thereafter, cells exposed to 33 mM glucose were treated with metformin (1 μM) or ASP (1 μM), as well as a combination of metformin and ASP for 6 h. In vitro studies revealed that ASP improved glucose metabolism by decreasing fatty acid uptake and subsequent β-oxidation through the decreased expression of adenosine monophosphate-activated protein kinase threonine 172 (pAMPK (Thr172)) and carnitine palmitoyltransferase 1 (CPT1), while increasing acetyl-CoA carboxylase (ACC) and glucose transporter 4 (GLUT4) expression. ASP inhibited high glucose induced loss of membrane potential in H9c2 cells as observed by an increase in 5' ,6,6'-tetrachloro-1,1',3,3' -tetraethylbenzimidazolyl-carbocyanine iodide (JC-1) ratio (orange\red fluorescence) and decreased apoptosis by reducing intracellular reactive oxygen species and DNA nick formation, while increasing glutathione, superoxide dismutase, uncoupling protein 2 (UCP2), and Bcl-2\Bax ratio.

CONCLUSION

Our study provides evidence that ASP increases glucose oxidation and modulates fatty acid utilization producing a favorable substrate shift in H9c2 cardiomyocytes exposed to high glucose. Such a favorable shift will be of importance in the protection of cardiomyocytes in the diabetic heart.

Iron chelators with topoisomerase-inhibitory activity and their anticancer applications

SIGNIFICANCE

Iron and topoisomerases are abundant and essential cellular components. Iron is required for several key processes such as DNA synthesis, mitochondrial electron transport, synthesis of heme, and as a co-factor for many redox enzymes. Topoisomerases serve as critical enzymes that resolve topological problems during DNA synthesis, transcription, and repair. Neoplastic cells have higher uptake and utilization of iron, as well as elevated levels of topoisomerase family members. Separately, the chelation of iron and the cytotoxic inhibition of topoisomerase have yielded potent anticancer agents.

RECENT ADVANCES

The chemotherapeutic drugs doxorubicin and dexrazoxane both chelate iron and target topoisomerase 2 alpha (top2α). Newer chelators such as di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone and thiosemicarbazone -24 have recently been identified as top2α inhibitors. The growing list of agents that appear to chelate iron and inhibit topoisomerases prompts the question of whether and how these two distinct mechanisms might interplay for a cytotoxic chemotherapeutic outcome.

CRITICAL ISSUES

While iron chelation and topoisomerase inhibition each represent mechanistically advantageous anticancer therapeutic strategies, dual targeting agents present an attractive multi-modal opportunity for enhanced anticancer tumor killing and overcoming drug resistance. The commonalities and caveats of dual inhibition are presented in this review.

FUTURE DIRECTIONS

Gaps in knowledge, relevant biomarkers, and strategies for future in vivo studies with dual inhibitors are discussed.

Dose- and time-dependent effects of doxorubicin on cytotoxicity, cell cycle and apoptotic cell death in human colon cancer cells

The cytostatic drug doxorubicin is a well-known chemotherapeutic agent which is used in treatment of a wide variety of cancers. A key factor in the response of cancer cells to chemotherapeutic drugs is the activation of the apoptotic pathway, a pathway that is often impaired in chemoresistant colon cancer cells. The aim of the present study was to investigate the effects of doxorubicin in Hct-116 human colon carcinoma cells in order to clarify if a time/concentration range for optimal doxorubicin-induced apoptosis exists. We compared a treatment schedule were cells were bolus incubated for 3h with doxorubicin followed by 24h in drug-free medium, with a continuous doxorubicin treatment schedule for 24h. Bolus incubation was carried out to determine effects of doxorubicin accumulated during the first 3h, whereas continuous incubation allowed further (continuous) exposure to doxorubicin. We found that bolus (3h) treatment with doxorubicin resulted in a dose-dependent decrease of viable cells and concomitant increase of apoptosis. Additionally, bolus (3h) doxorubicin incubation led to phosphorylation of p53 at serine 392, induction of p21, G2 arrest and increase of proapoptotic protein Bax. In contrast, continuous (24h) treatment with doxorubicin reduced the number of living cells with no parallel raise in the amount of dead cells. Continuous (24h) treatment with 5 microM doxorubicin resulted in cell cycle arrest in G0/G1 phase that was neither accompanied by phosphorylation and activation of p53 nor enhanced expression of p21. These results suggest that doxorubicin is able to induce cell death by apoptosis only at particular dose and treatment conditions and imply a completely different cellular response following bolus or continuous exposure to doxorubicin.

Maternally transmitted milk containing recombinant human catalase provides protection against oxidation for mouse offspring during lactation

Catalase plays an important role in protecting organisms against oxidative damage caused by reactive oxygen species (ROS) by degrading surplus hydrogen peroxide. Addition of exogenous catalase can alleviate injuries caused by ROS. Thus, production of human catalase through genetic engineering will meet the increasing therapeutic demand for this enzyme. In this study, we successfully expressed the recombinant gene in mouse mammary gland, and biologically active human catalase was secreted into the milk of the transgenic mice. The peroxisomal targeting sequence (PTS) within the catalase gene had no significant negative effect on the secretion of the recombinant protein. Intake of the transgenic milk by the pups was found to decrease lipid peroxidation, increase the total superoxide dismutase (T-SOD) activity in the brain, and enhance the total antioxidative capacity (T-AOC) of brain, liver, and serum. To our knowledge, this is the first example of efficient production of biologically active human catalase in the milk of transgenic animals. Our study suggests that scaled-up production in transgenic farm animals would yield sufficient human catalase for biomedical research and clinical therapies.

Iron is not involved in oxidative stress-mediated cytotoxicity of doxorubicin and bleomycin

BACKGROUND AND PURPOSE

The anticancer drugs doxorubicin and bleomycin are well-known for their oxidative stress-mediated side effects in heart and lung, respectively. It is frequently suggested that iron is involved in doxorubicin and bleomycin toxicity. We set out to elucidate whether iron chelation prevents the oxidative stress-mediated toxicity of doxorubicin and bleomycin and whether it affects their antiproliferative/proapoptotic effects.

EXPERIMENTAL APPROACH

Cell culture experiments were performed in A549 cells. Formation of hydroxyl radicals was measured in vitro by electron paramagnetic resonance (EPR). We investigated interactions between five iron chelators and the oxidative stress-inducing agents (doxorubicin, bleomycin and H(2)O(2)) by quantifying oxidative stress and cellular damage as TBARS formation, glutathione (GSH) consumption and lactic dehydrogenase (LDH) leakage. The antitumour/proapoptotic effects of doxorubicin and bleomycin were assessed by cell proliferation and caspase-3 activity assay.

KEY RESULTS

All the tested chelators, except for monohydroxyethylrutoside (monoHER), prevented hydroxyl radical formation induced by H(2)O(2)/Fe(2+) in EPR studies. However, only salicylaldehyde isonicotinoyl hydrazone and deferoxamine protected intact A549 cells against H(2)O(2)/Fe(2+). Conversely, the chelators that decreased doxorubicin and bleomycin-induced oxidative stress and cellular damage (dexrazoxane, monoHER) were not able to protect against H(2)O(2)/Fe(2+).

CONCLUSIONS AND IMPLICATIONS

We have shown that the ability to chelate iron as such is not the sole determinant of a compound protecting against doxorubicin or bleomycin-induced cytotoxicity. Our data challenge the putative role of iron and hydroxyl radicals in the oxidative stress-mediated cytotoxicity of doxorubicin and bleomycin and have implications for the development of new compounds to protects against this toxicity.

Cardioprotective Effects of a Novel Iron Chelator, Pyridoxal 2-Chlorobenzoyl Hydrazone, in the Rabbit Model of Daunorubicin-Induced Cardiotoxicity

Iron chelation is the only pharmacological intervention against anthracycline cardiotoxicity whose effectiveness has been well documented both experimentally and clinically. In this study, we aimed to assess whether pyridoxal 2-chlorobenzoyl hydrazone (o-108, a strong iron chelator) can provide effective protection against daunorubicin (DAU)-induced chronic cardiotoxicity in rabbits. First, using the HL-60 leukemic cell line, it was shown that o-108 has no potential to blunt the antiproliferative efficacy of DAU. Instead, o-108 itself moderately inhibited cell proliferation. In vivo, chronic DAU treatment (3 mg/kg weekly for 10 weeks) induced mortality (33%), left ventricular (LV) dysfunction, a troponin T rise, and typical morphological LV damage. In contrast, all animals treated with 10 mg/kg o-108 before DAU survived without a significant drop in the LV ejection fraction (63.2 +/- 0.5 versus 59.2 +/- 1.0%, beginning versus end, not significant), and their cardiac contractility (dP/dt(max)) was significantly higher than in the DAU-only group (1131 +/- 125 versus 783 +/- 53 kPa/s, p < 0.05), which corresponded with histologically assessed lower extent and intensity of myocardial damage. Although higher o-108 dose (25 mg/kg) was well tolerated when administered alone, in combination with DAU it led to rather paradoxical and mostly negative results regarding both cardioprotection and overall mortality. In conclusion, we show that shielding of free intracellular iron using a potent lipophilic iron chelator is able to offer a meaningful protection against chronic anthracycline cardiotoxicity. However, this approach lost its potential with the higher chelator dose, which suggests that iron might play more complex role in the pathogenesis of this disease than previously assumed.

Thrombopoietin protects against in vitro and in vivo cardiotoxicity induced by doxorubicin

BACKGROUND

Doxorubicin (DOX) is an important antineoplastic agent. However, the associated cardiotoxicity, possibly mediated by the production of reactive oxygen species, has remained a significant and dose-limiting clinical problem. Our hypothesis is that the hematopoietic/megakaryocytopoietic growth factor thrombopoietin (TPO) protects against DOX-induced cardiotoxicity and might involve antiapoptotic mechanism exerted on cardiomyocytes.

METHODS AND RESULTS

In vitro investigations on H9C2 cell line and spontaneously beating cells of primary, neonatal rat ventricle, as well as an in vivo study in a mouse model of DOX-induced acute cardiomyopathy, were performed. Our results showed that pretreatment with TPO significantly increased viability of DOX-injured H9C2 cells and beating rates of neonatal myocytes, with effects similar to those of dexrazoxane, a clinically approved cardiac protective agent. TPO ameliorated DOX-induced apoptosis of H9C2 cells as demonstrated by assays of annexin V, active caspase-3, and mitochondrial membrane potential. In the mouse model, administration of TPO (12.5 microg/kg IP for 3 alternate days) significantly reduced DOX-induced (20 mg/kg) cardiotoxicity, including low blood cell count, cardiomyocyte lesions (apoptosis, vacuolization, and myofibrillar loss), and animal mortality. Using Doppler echocardiography, we observed increased heart rate, fractional shortening, and cardiac output in animals pretreated with TPO compared with those receiving DOX alone.

CONCLUSIONS

These data have provided the first evidence that TPO is a protective agent against DOX-induced cardiac injury. We propose to further explore an integrated program, incorporating TPO with other protocols, for treatment of DOX-induced cardiotoxicity and other forms of cardiomyopathy.

The influence of the time interval between monoHER and doxorubicin administration on the protection against doxorubicin-induced cardiotoxicity in mice

PURPOSE

Despite its well-known cardiotoxicity, the anthracyclin doxorubicin (DOX) continues to be an effective and widely used chemotherapeutic agent. DOX-induced cardiac damage presumably results from the formation of free radicals by DOX. Reactive oxygen species particularly affect the cardiac myocytes because these cells seem to have a relatively poor antioxidant defense system. The semisynthetic flavonoid monohydroxyethylrutoside (monoHER) showed cardioprotection against DOX-induced cardiotoxicity through its radical scavenging and iron chelating properties. Because of the relatively short final half-life of monoHER (about 30 min), it is expected that the time interval between monoHER and DOX might be of influence on the cardioprotective effect of monoHER. Therefore, the aim of the present study was to investigate this possible effect.

METHODS

Six groups of 6 BALB/c mice were treated with saline, DOX alone or DOX (4 mg/kg i.v.) preceded by monoHER (500 mg/kg i.p.) with an interval of 10, 30, 60 or 120 min. After a 6-week treatment period and additional observation for 2 weeks, the mice were sacrificed. Their cardiac tissues were processed for light microscopy, after which cardiomyocyte damage was evaluated according to Billingham (in Cancer Treat Rep 62(6):865-872, 1978). Microscopic evaluation revealed that treatment with DOX alone induced significant cardiac damage in comparison to the saline control group (P<0.001).

RESULTS

The number of damaged cardiomyocytes was 9.6-fold (95% CI 4.4-21.0) higher in mice treated with DOX alone than that in animals of the control group. The ratio of aberrant cardiomyocytes in mice treated with DOX preceded by monoHER and those in mice treated with saline ranged from 1.6 to 2.8 (mean 2.2, 95% CI 1.2-4.1, P=0.019). The mean protective effect by adding monoHER before DOX led to a significant 4.4-fold reduction (P<0.001, 95% CI 2.3-8.2) of abnormal cardiomyocytes. This protective effect did not depend on the time interval between monoHER and DOX administration (P=0.345).

CONCLUSION

The results indicate that in an outpatient clinical setting monoHER may be administered shortly before DOX.

Protective effect ofSpirulina against doxorubicin-induced cardiotoxicity

The generation of reactive oxygen species and mitochondrial dysfunction has been implicated in doxorubicin (DOX)-induced cardiotoxicity. The aim of the present study was to determine whether Spirulina, a blue-green algae, could serve as a cardioprotective agent during DOX treatment in a mouse model. Mice were treated with DOX (4 mg/kg bw, intraperitoneally), weekly, for 4 weeks. Spirulina was administered orally for 3 days twice daily, then for 7 weeks along with the four equal injections of DOX. Cardiotoxicity was assessed, at 3 weeks after the end of the DOX-treatment period, by mortality, volume of ascites, liver congestion, oxidative stress and ultrastructural changes of heart tissue. The DOX-treated animals showed higher mortality (53%) and more ascites. Myocardial damage, as assessed by ultrastructural changes, showed loss of myofibrils, cytoplasmic vacuolization and mitochondrial swelling. Myocardial superoxide dismutase and glutathione peroxidase activities were decreased and lipid peroxidation was increased. Pretreatment with Spirulina significantly protected the mice from DOX-induced cardiotoxic effects as evidenced from lower mortality (26%), less ascites, lower levels of lipid peroxidation, normalization of antioxidant enzymes and ultrastructural studies showing minimal damage to the heart. In vitro cytotoxic studies using ovarian cancer cells demonstrated that Spirulina did not compromise the anti-tumor activity of doxorubicin. These results suggest that Spirulina has a protective effect against cardiotoxicity induced by DOX and it may, therefore, improve the therapeutic index of DOX.