Metallothionein protects against doxorubicin-induced cardiomyopathy through inhibition of superoxide generation and related nitrosative impairment

In vivo cardioprotective effect of zinc oxide nanoparticles against doxorubicin-induced myocardial infarction by enhancing the antioxidant system and nitric oxide production

BACKGROUND

Myocardial infarction (MI) is the result of reduced or stopped blood supply to a section of the myocardium. Regardless of its potential effectiveness in the treatment of several types of cancers, doxorubicin (DOX) capabilities are restricted because of its widespread cardiotoxic impact.

AIM

In this study, the protective effect of zinc oxide nanoparticles against doxorubicin-induced myocardial infarction in rats is examined.

METHODS

Zinc oxide nanoparticles (ZnO NPs) were synthesized and characterized using X-ray diffraction, transmission electron microscope, and UV-Vis spectral analysis. A total cumulative dose of DOX (18 mg/kg body weight, i.p.) was injected once daily on days 2, 4, 6, 8, 10, and 12 (i.p.) to induce MI in rats. 24 rats were divided into 4 groups; control, MI, and MI treated with two doses of ZnO NPs (45 and 22.5 mg/kg).

RESULTS

The treatment with ZnO NPs restored ST-segment near normal, ameliorated the changes in cardiac troponin T, creatine kinase, lactate dehydrogenase, aspartate aminotransferase, alanine amino transferase, alkaline phosphatase, total proteins, malondialdehyde, nitric oxide, reduced glutathione, and catalase.The histological investigation revealed that ZnO NPs treated group showed marked improvement in the examined cardiac muscle and liver in numerous sections.The lower dose of ZnO NPs (22.5 mg/kg) was significantly more effective than the higher dose (45 mg/kg).

CONCLUSION

The effect of ZnO NPs against doxorubicin-induced myocardial infarction in rats was assessed and the results revealed a successful cardioprotective potency through enhancing the antioxidant system and stimulating nitric oxide production in myocardial infarcted rats. This work implies that ZnO NPs could serve as promising agents for treating doxorubicin-induced cardiotoxicity.

Cardiac Damage in Anthracyclines Therapy: Focus on Oxidative Stress and Inflammation

Significance: Despite their serious side effects, anthracyclines (ANTs) are the most prescribed chemotherapeutic drugs because of their strong efficacy in both solid and hematological tumors. A major limitation to ANTs clinical application is the severe cardiotoxicity observed both acutely and chronically. The mechanism underlying cardiac dysfunction under chemotherapy is mainly dependent on the generation of oxidative stress and systemic inflammation, both of which lead to progressive cardiomyopathy and heart failure. Recent Advances: Over the years, the iatrogenic ANTs-induced cardiotoxicity was believed to be simply given by iron metabolism and reactive oxygen species production; however, several experimental data indicate that ANTs may use alternative damaging mechanisms, such as topoisomerase 2β inhibition, inflammation, pyroptosis, immunometabolism, and autophagy. Critical Issues: In this review, we aimed at discussing ANTs-induced cardiac injury from different points of view, updating and focusing on oxidative stress and inflammation, since these pathways are not exclusive or independent from each other but they together importantly contribute to the complexity of ANTs-induced multifactorial cardiotoxicity. Future Directions: A deeper understanding of the mechanistic signaling leading to ANTs side effects could reveal crucial targeting molecules, thus representing strategic knowledge to promote better therapeutic efficacy and lower cardiotoxicity during clinical application.

Ajwa Nanopreparation Prevents Doxorubicin-Associated Cardiac Dysfunction: Effect on Cardiac Ischemia and Antioxidant Capacity

Background: This study evaluated the cardioprotective effect of Ajwa nano-preparation against doxorubicin-associated cardiotoxicity. Methods: Twenty-four male Wistar rats (200-250 g) were divided into 3 groups. One group was given the nanopreparation containing both Ajwa fruit and pit in a dose of 1.4 g/kg orally 1 hour before doxorubicin infusion (Dates-DOX group). Another group was given the vehicle for 1 hour before doxorubicin infusion (DOX group). The third group received the vehicle but no DOX infusion (time control). Cardiac hemodynamics, blood pressure, cardiac contractility, and conductivity were recorded before and after 45 minutes of infusion of doxorubicin (15 mg/kg, slow intravenous over 45 minutes). Blood samples were collected before and after doxorubicin infusion. Heart tissue samples were collected and snap frozen until assay of reduced glutathione. Results: Rats pre-administered Ajwa nanopreparation were protected from doxorubicin-associated systolic and diastolic dysfunction based on the significant elevation in the rate of rise in left ventricular pressure (dp/dt_max) and (dp/dt_min) compared with the DOX group. In addition, it prevented the doxorubicin-associated ischemia based on the significant shortening in QT interval, JT interval, and T_peak-T_end interval versus the DOX group. There was no effect on atrial conductivity (PR interval and P duration). Ajwa pretreatment increased the antioxidant capacity of cardiac tissue, as evidenced by increasing the cardiac content of reduced glutathione compared with the untreated doxorubicin group. Conclusion: Ajwa nanopreparation protects from doxorubicin-associated cardiotoxicity through alleviating cardiac ischemia and increasing cardiac antioxidant capacity.

Pulmonary arterial hypertension and the potential roles of metallothioneins: A focused review

The pathophysiology of pulmonary arterial hypertension (PAH) is underlined by cell proliferation and vasoconstriction of pulmonary arterioles this involves multiple molecular factors or proteins, but it is not clear what the exact roles of these factors/proteins are. In addition, there may be other factors/proteins that have not been identified that contribute to PAH pathophysiology. Therefore, research has focused on investigating novel role players, in order to facilitate a better understanding of how PAH develop. Evidence suggest that mitochondrial regulators are key role players in PAH pathophysiology, but regulators that have not received sufficient attention in PAH are metallothioneins (MTs). In PAH patients, MT expression is elevated compared to healthy individuals, suggesting that MTs may be possible biomarkers. In other disease-models, MTs have been shown to regulate cell proliferation and vasoconstriction, processes that are instrumental in PAH pathophysiology. Due to the involvement of these processes in PAH pathophysiology and the ability of MTs to modulate them, this paper propose that cellular MTs may also play a role in PAH development. This paper suggests that PAH-research should perhaps begin to investigate the involvement of cellular MTs in the development of PAH.

The roles of metallothioneins in carcinogenesis

Metallothioneins (MTs) are small cysteine-rich proteins that play important roles in metal homeostasis and protection against heavy metal toxicity, DNA damage, and oxidative stress. In humans, MTs have four main isoforms (MT1, MT2, MT3, and MT4) that are encoded by genes located on chromosome 16q13. MT1 comprises eight known functional (sub)isoforms (MT1A, MT1B, MT1E, MT1F, MT1G, MT1H, MT1M, and MT1X). Emerging evidence shows that MTs play a pivotal role in tumor formation, progression, and drug resistance. However, the expression of MTs is not universal in all human tumors and may depend on the type and differentiation status of tumors, as well as other environmental stimuli or gene mutations. More importantly, the differential expression of particular MT isoforms can be utilized for tumor diagnosis and therapy. This review summarizes the recent knowledge on the functions and mechanisms of MTs in carcinogenesis and describes the differential expression and regulation of MT isoforms in various malignant tumors. The roles of MTs in tumor growth, differentiation, angiogenesis, metastasis, microenvironment remodeling, immune escape, and drug resistance are also discussed. Finally, this review highlights the potential of MTs as biomarkers for cancer diagnosis and prognosis and introduces some current applications of targeting MT isoforms in cancer therapy. The knowledge on the MTs may provide new insights for treating cancer and bring hope for the elimination of cancer.

Nrf2 expression and function, but not MT expression, is indispensable for sulforaphane-mediated protection against intermittent hypoxia-induced cardiomyopathy in mice

We reported previously that nuclear factor erythroid 2-related factor 2 (Nrf2) and metallothionein (MT) play critical roles in preventing intermittent hypoxia (IH)-induced cardiomyopathy. In addition, positive feedback regulation between Nrf2 and MT is required for the efficient compensative responses of the heart to IH. As an activator of Nrf2, sulforaphane (SFN) has attracted attention as a potential protective agent against cardiovascular disease. Here, we investigated whether SFN can up-regulate cardiac Nrf2 expression and function, as well as MT expression, to prevent IH-induced cardiomyopathy, and if so, whether Nrf2 and MT are indispensable for this preventive effect. Nrf2-knock-out (Nrf2-KO) or MT-KO mice and their wild-type (WT) equivalents were exposed to IH for 4 weeks with or without SFN treatment. SFN almost completely prevented IH-induced cardiomyopathy in WT mice, and this preventive effect was abolished in Nrf2-KO mice but retained in MT-KO mice. In IH-exposed WT mice, SFN induced significant increases in the expression levels of Nrf2 and its downstream antioxidant target genes, as well as those of MT, but these effects were not seen in IH-exposed Nrf2-KO mice. By contrast, KO of MT did not affect the ability of SFN to up-regulate the expression of Nrf2 and its downstream antioxidant targets. These results suggest that SFN-induced MT expression is Nrf2-dependent, and SFN prevents IH-induced cardiomyopathy in a Nrf2-dependent manner, for which MT is dispensable. This study provides important information that is relevant to the potential use of SFN to prevent IH-induced cardiomyopathy.

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Sulforaphane (SFN) protects from intermittent-hypoxia (IH)-induced cardiomyopathy;

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SFN can increase both Nrf2 and metallothionein (MT) but the latter is Nrf2 dependent.

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SFN protects the heart from IH in wild-type and MT-KO mice, but not in Nrf2 mice.

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Nrf2 is indispensable, but not MT, for SFN to protect from IH-induced cardiomyopathy.

Curcumin ameliorates doxorubicin-induced cardiotoxicity by abrogation of inflammation, apoptosis, oxidative DNA damage, and protein oxidation in rats

Doxorubicin (DXR) is a highly effective drug for chemotherapy. However, cardiotoxicity reduces its clinical utility in humans. The present study aimed to assess the ameliorative effect of curcumin against DXR-induced cardiotoxicity in rats. Rats were subjected to oral treatment of curcumin (100 and 200 mg/kg body weight) for 7 days. Cardiotoxicity was induced by single intraperitoneal injection of DXR (40 mg/kg body weight) on the 5th day and the rats sacrificed on 8th day. Curcumin ameliorated DXR-induced lipid peroxidation, glutathione depletion, decrease in antioxidant (superoxide dismutase, catalase, and glutathione peroxidase) enzyme activities, and cardiac toxicity markers (CK-MB, LDH, and cTn-I). Curcumin also attenuated activities of Caspase-3, cyclooxygenase-2, inducible nitric oxide synthase, and levels of nuclear factor kappa-B, tumor necrosis factor-α, and interleukin-1β, and cardiac tissue damages that were induced by DXR. Moreover, curcumin decreased the expression of 8-OHdG and 3,3'-dityrosine. This study demonstrated that curcumin has a multi-cardioprotective effect due to its antioxidant, anti-inflammatory, and antiapoptotic properties.

Metallothionein prevents doxorubicin cardiac toxicity by indirectly regulating the uncoupling proteins 2

Doxorubicin (Dox) is a broad-spectrum anticancer agent, but its clinical use is restricted due to irreversible cardiac toxicity. Metallothionein (MT) can inhibit Dox-induced cardiac toxicity. Applying a proteomics approach we determined that uncoupling proteins (UCPs) may be implicated in this process. This study was designed to examine the mechanisms of MT against Dox cardiac toxicity and the link between MT and UCP2. In vivo, wild-type (MT^+/+) and MT-I/II null (MT^-/-) mice were given a single dose of Dox (15 mg/kg, i.p.) and sacrificed at 4 days after Dox injection. In vitro, cardiomyocytes were prepared from MT^-/- and MT^+/+ neonatal mice and cardiomyocytes were pretreated with typical antioxidant NAC or the UCP2 inhibitor genipin followed by exposure to Dox. Based on the results, genipin enhanced Dox-induced oxidative injury, particularly in MT^-/- cardiomyocyte. UCP2 levels in MT^-/- mice were significantly lower compared to MT^+/+ mice treated with Dox. Co-immunoprecipitation demonstrated that MT did not directly bind to UCP2. The NAC and Nrf2 activator oltipraz inhibit the decrease of UCP2 expression induced by Dox. Therefore, attenuating free radical damage with UCP2 help MT antagonize the Dox-induced cardiac toxicity, but does not directly bind MT. MT may regulate UCP2 expression by up-regulating Nrf2.

Characterization of Fluorescein-Based Monoboronate Probe and Its Application to the Detection of Peroxynitrite in Endothelial Cells Treated with Doxorubicin

Boronate probes have emerged recently as a versatile tool for the detection of reactive oxygen and nitrogen species. Here, we present the characterization of a fluorescein-based monoboronate probe, a 4-(pinacol boronate)benzyl derivative of fluorescein methyl ester (FBBE), that proved to be useful to detect peroxynitrite in cell culture experiments. The reactivity of FBBE toward peroxynitrite as well hypochlorite, hydrogen peroxide, and tyrosyl hydroperoxide was determined. Second-order rate constants of the reactions of FBBE with peroxynitrite, HOCl, and H2O2 at pH 7.4 were equal to (2.8 ± 0.2) × 10(5) M(-1) s(-1), (8.6 ± 0.5) × 10(3) M(-1) s(-1), and (0.96 ± 0.03) M(-1) s(-1), respectively. The presence of glutathione completely blocked the oxidation of the probe by HOCl and significantly inhibited its oxidation by H2O2 and tyrosyl hydroperoxide but not by peroxynitrite. The oxidative conversion of the probe was also studied in the systems generating singlet oxygen, superoxide radical anion, and nitric oxide in the presence and absence of glutathione. Spectroscopic characterization of FBBE and its oxidation product has been also performed. The differences in the reactivity pattern were supported by DFT quantum mechanical calculations. Finally, the FBBE probe was used to study the oxidative stress in endothelial cells (Ea.hy926) incubated with doxorubicin, a quinone anthracycline antibiotic. In endothelial cells pretreated with doxorubicin, FBBE was oxidized, and this effect was reversed by PEG-SOD and L-NAME but not by catalase.

Protective effect of Sheng-Mai Yin, a traditional Chinese preparation, against doxorubicin-induced cardiac toxicity in rats

Background

Sheng-Mai Yin (SMY), a modern Chinese formula based on Traditional Chinese Medicine theory, has been used to treat cardiovascular diseases in Eastern Asia. Our study focuses on the cardioprotection of SMY against doxorubicin (DOX)-induced cardiac toxicity in vivo.

Methods

Rats were injected with DOX (2.5 mg/kg) in six injections over a 2-week period. SMY was administrated intragastrically at the dose of 8.35, 16.7 and 33.4 g/kg, or 16.7 g/kg only twice a day concurrently with DOX for the 2-weeks. A series of assays were performed to detect the effects of SMY on: (i) heart weight index (HWI) and left ventricular mass index (LVMI); (ii) cardiac function; (iii) heart tissue morphology; (iv) the contents of carboxy terminal propeptide of procollagen typeI (PICP), amino terminal propeptide of procollagen type III (PШNP), transforming growth factor-β1 (TGF-β1), B-type natriuretic peptide (BNP), monocyte chemoattractant protein-1 (MCP-1), interferon gamma (INF-γ) and interleukin 6 (IL-6) by ELISA; (v) the mRNA levels of TGF-β1 and toll-like receptor-2 (TLR2); and (vi) protein level of TGF-β1.

Results

Rats treated with SMY displayed the reductions of BNP and CK-MB increased by DOX in a dose-dependent manner. Moderate dose of SMY exhibited the correction for the increased HWI, LVMI, and the injured cardiac function, as well as the collagen accumulation. In addition, cardioprotection of SMY against DOX-induced cardiac toxicity was demonstrated by the reduction of myocardial fibrosis, characterized by the suppression of PICP, PШNP and TGF-β1, as well as the anti-inflammation and the regulation for cardiac immune microenvironment, characterized by the inhibition of TLR2, MCP-1, INF-γ and IL-6.

Conclusions

SMY may protect heart function through the restriction of myocardial fibrosis induced by DOX, which suggests the potentially therapeutic effect of SMY on DOX-induced cardiomyopathy.

Zinc-induced metallothionein overexpression prevents doxorubicin toxicity in cardiomyocytes by regulating the peroxiredoxins

1. Cardiotoxicity is an important factor that limits the clinical use of doxorubicin (Dox). Metallothionein (MT) can antagonize the Dox-induced cardiotoxicity. Using a proteomics approach we have detected that major peroxiredoxins (Prxs) may be involved in this process. In the present study, we further investigate the mechanisms of the MT effects against Dox-induced cytotoxicity and the interactions between MT and Prxs. 2. We have established a primary cardiomyocyte culture system from MT-I/II null (MT(-/-)) and corresponding wild type (MT(+/+)) neonatal mice, and pretreated the MT(+/+) cardiomyocytes with ZnCl2 to establish the MT overexpression cardiomyocyte model. 3. Based on the results, in MT(+/+) cardiomyocytes, ZnCl2 pretreatment significantly increased the cardiomyocytes MT levels and inhibited the cardiotoxicity of Dox; it can resist LDH leakage, cardiomyocyte apoptosis, DNA damage, ROS accumulation and inhibit the decrease in activity of antioxidant enzymes induced by Dox. Moreover, ZnCl2 enhanced the expression of Prx-2, -3, -5 and -6, it can inhibit the expression of Prxs decrease in MT(+/+) cardiomyocytes induced by Dox, but had no effect in MT(-/-) cardiomyocytes. 4. Therefore, the present study suggests that ZnCl2 can protect the cardiomyocytes from the Dox-induced oxidative injury and can inhibit the changes in Prxs expression through induced MT overexpression.

JAK2/STAT3 Pathway Mediates Protection of Metallothionein Against Doxorubicin-Induced Cytotoxicity in Mouse Cardiomyocytes

Doxorubicin (Dox) is one of the most important anticancer agents; however, its clinical application is limited by its severe cardiotoxicity. In our previous study, we found that the gene expression levels of the Janus-activated kinase/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway were different between MT(-/-) cardiomyocytes and MT(+/+) cardiomyocytes when they were treated with Dox. Thus, this study was intended to investigate the role of JAK2/STAT3 pathway in metallothionein (MT) protection of Dox-induced cardiotoxicity. Tyrphostin AG490 (α-cyano-(3,4-dihydroxy)-N-benzylcinnamide) is a synthetic protein tyrosine kinase inhibitor which at first has been considered as a specific JAK2 inhibitor and can inhibit the JAK2/STAT3 signaling pathway. In the present study, AG490 was used to assess the role of JAK2/STAT3 in MT protection against Dox-induced cardiotoxicity. The AG490 can attenuate the MT protection by increasing lactate dehydrogenase and the number of apoptotic cells. Interestingly, pretreated with AG490, MT(-/-) cardiomyocytes were more sensitive than MT(+/+) to Dox-induced cytotoxicity as measured by reactive oxygen species generation, lipid peroxidation, and protein carbonylation. Metallothionein 1 and MT-2 messenger RNA were upregulated by Dox, and AG490 decreased the protein expression of MT-1 and MT-2. After Dox treatment, the protein expression of p-Jak2 and p-Stat3 levels was significantly increased in MT(+/+) cardiomyocytes, suggesting that the JAK2/STAT3 pathway was partially involved in MT protection against Dox-induced cardiotoxicity.

Metallothioneins attenuate paraquat-induced acute lung injury in mice through the mechanisms of anti-oxidation and anti-apoptosis

Paraquat (PQ) is a widely used herbicide, and lung is the primary target of PQ poisoning. Metallothionein (MT) is a potent antioxidant and free radical scavenger, and has been shown to play a protective role in lung injury induced by different stressors. This study was undertaken to evaluate the protective potential of MT against PQ-induced acute lung injury using MT-I/II null (MT(-/-)) mice. Wild-type (MT(+/+)) mice and MT(-/-) mice were given one intragastric administration of 50mg/kg PQ for 24h, and it was revealed that MT(-/-) mice were more susceptible to PQ-induced acute lung injury than MT(+/+) mice evidenced by the following findings. As compared with MT(+/+) mice, MT(-/-) mice presented more severe histopathological lesions in the lung, higher pulmonary malondialdehyde content, and more reduced pulmonary antioxidative enzymes activities. PQ also induced more apoptosis in pneumocytes from MT(-/-) mice, and the expressions of apoptosis-related proteins Bax, Bcl-2, cleaved-caspase-3, and the ratio of Bax/Bcl-2 were all more significantly increased in PQ-treated MT(-/-) mice. Our results clearly demonstrate that endogenous MT can attenuate PQ-induced acute lung injury, possibly through the mechanisms of anti-oxidation and anti-apoptosis.

Protective effect of resveratrol against doxorubicin-induced cardiac toxicity and fibrosis in male experimental rats

The possible effectiveness of resveratrol, a polyphenol present in different plants comprising berries, grapes and peanuts, on the prevention of doxorubicin-induced cardiac toxicity and fibrosis was investigated. Forty adult male Wistar albino rats were divided into four groups. Group I received normal saline, group II gavaged with resveratrol (20 mg/kg, daily for 4 weeks), group III received doxorubicin (2.5 mg/kg i.p. in six injections for 2 weeks; accumulative dose of 15 mg/kg), and group IV received doxorubicin + resveratrol (starting resveratrol intake 2 weeks before doxorubicin administration). Resveratrol significantly alleviated the increase in left ventricular lipid peroxidation, hydroxyproline, and tumor necrosis factor alpha levels as well as serum creatine kinase-myocardial band (CK-MB) activity and prevented the decrease in body and heart weights in doxorubicin-treated group. However, a marked protection against reduced glutathione content depletion and superoxide dismutase activity reduction was observed in the left ventricles of rats pretreated with resveratrol in combination with doxorubicin. Resveratrol also ameliorated the up-regulation of left ventricular caspase-3 and transforming growth factor-beta1 gene expression as well as left ventricular histopathological changes including necrosis and fibrosis induced by doxorubicin. Collectively, our results suggest that resveratrol provides a significant protection against doxorubicin-induced cardiotoxicity and fibrosis in rats. Therefore, it may be used as a promising cardioprotective agent in patients treated with doxorubicin due to malignant diseases. So, further clinical trials are required to confirm these findings.

Cardioprotection against doxorubicin by metallothionein Is associated with preservation of mitochondrial biogenesis involving PGC-1α pathway

Metallothionein (MT) has been shown to inhibit cardiac oxidative stress and protect against the cardiotoxicity induced by doxorubicin (DOX), a potent and widely used chemotherapeutic agent. However, the mechanism of MT׳s protective action against DOX still remains obscure. Mitochondrial biogenesis impairment has been implicated to play an important role in the etiology and progression of DOX-induced cardiotoxicity. Increasing evidence indicates an intimate link between MT-mediated cardioprotection and mitochondrial biogenesis. This study was aimed to explore the possible contribution of mitochondrial biogenesis in MT׳s cardioprotective action against DOX. Adult male MT-I/II-null (MT(-/-)) and wild-type (MT(+/+)) mice were given a single dose of DOX intraperitoneally. Our results revealed that MT deficiency significantly sensitized mice to DOX-induced cardiac dysfunction, ultrastructural alterations, and mortality. DOX disrupted cardiac mitochondrial biogenesis indicated by mitochondrial DNA copy number and decreased mitochondrial number, and these effects were greater in MT(-/-) mice. Basal MT effectively protected against DOX-induced inhibition on the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a key regulator of mitochondrial biogenesis, and its downstream factors including mitochondrial transcription factor A. Moreover, MT was found to preserve the protein expression of manganese superoxide dismutase, a transcriptional target of PGC-1α. in vitro study showed that MT absence augmented DOX-induced increase of mitochondrial superoxide production in primary cultured cardiomyocytes. These findings suggest that MT׳s cardioprotection against DOX is mediated, at least in part, by preservation of mitochondrial biogenesis involving PGC-1α pathway.

Therapeutic applications of PARP inhibitors: anticancer therapy and beyond

The aim of this article is to describe the current and potential clinical translation of pharmacological inhibitors of poly(ADP-ribose) polymerase (PARP) for the therapy of various diseases. The first section of the present review summarizes the available preclinical and clinical data with PARP inhibitors in various forms of cancer. In this context, the role of PARP in single-strand DNA break repair is relevant, leading to replication-associated lesions that cannot be repaired if homologous recombination repair (HRR) is defective, and the synthetic lethality of PARP inhibitors in HRR-defective cancer. HRR defects are classically associated with BRCA1 and 2 mutations associated with familial breast and ovarian cancer, but there may be many other causes of HRR defects. Thus, PARP inhibitors may be the drugs of choice for BRCA mutant breast and ovarian cancers, and extend beyond these tumors if appropriate biomarkers can be developed to identify HRR defects. Multiple lines of preclinical data demonstrate that PARP inhibition increases cytotoxicity and tumor growth delay in combination with temozolomide, topoisomerase inhibitors and ionizing radiation. Both single agent and combination clinical trials are underway. The final part of the first section of the present review summarizes the current status of the various PARP inhibitors that are in various stages of clinical development. The second section of the present review summarizes the role of PARP in selected non-oncologic indications. In a number of severe, acute diseases (such as stroke, neurotrauma, circulatory shock and acute myocardial infarction) the clinical translatability of PARP inhibition is supported by multiple lines of preclinical data, as well as observational data demonstrating PARP activation in human tissue samples. In these disease indications, PARP overactivation due to oxidative and nitrative stress drives cell necrosis and pro-inflammatory gene expression, which contributes to disease pathology. Accordingly, multiple lines of preclinical data indicate the efficacy of PARP inhibitors to preserve viable tissue and to down-regulate inflammatory responses. As the clinical trials with PARP inhibitors in various forms of cancer progress, it is hoped that a second line of clinical investigations, aimed at testing of PARP inhibitors for various non-oncologic indications, will be initiated, as well.

Chemotherapy targeting by DNA capture in viral protein particles

AIM

This study tests the hypothesis that DNA intercalation and electrophilic interactions can be exploited to noncovalently assemble doxorubicin in a viral protein nanoparticle designed to target and penetrate tumor cells through ligand-directed delivery. We further test whether this new paradigm of doxorubicin targeting shows therapeutic efficacy and safety in vitro and in vivo.

MATERIALS & METHODS

We tested serum stability, tumor targeting and therapeutic efficacy in vitro and in vivo using biochemical, microscopy and cytotoxicity assays.

RESULTS

Self-assembly formed approximately 10-nm diameter serum-stable nanoparticles that can target and ablate HER2+ tumors at >10× lower dose compared with untargeted doxorubicin, while sparing the heart after intravenous delivery. The targeted nanoparticle tested here allows doxorubicin potency to remain unaltered during assembly, transport and release into target cells,while avoiding peripheral tissue damage and enabling lower, and thus safer, drug dose for tumor killing.

CONCLUSION

This nanoparticle may be an improved alternative to chemical conjugates and signal-blocking antibodies for tumor-targeted treatment.

Cardioprotective Activity of Methanol Extract of fruit of Trichosanthes cucumerina on Doxorubicin-induced Cardiotoxicity in Wistar Rats

AIM AND OBJECTIVE

The objective was to determine the activity of methanol extract of fruit of Trichosanthes cucumerina in doxorubicin-induced cardiotoxicity in rats.

MATERIALS AND METHODS

The methanol extract of fruit of T. cucumerina was prepared. Male Wistar rats were divided in four groups. Group I was vehicle control. Group II animals received doxorubicin 4 mg/kg i.p. on days 21, 28, 35, and 42. Group III and IV animals were treated with methanol extract of T. cucumerina (500 and 1000 mg/kg, respectively) for 49 days. Doxorubicin was administered on days 21, 28, 35, and 42 days. The parameters of study were body weight, serum biomarkers, ECG, blood pressure, and left ventricular function. At the end of the study, the histology of heart, liver, and kidney was carried out.

RESULTS

Cardiac toxicity by doxorubicin was manifested as body weight loss, elevated serum LDH and CK-MB, increased ST, QT and QRS complex, reduced blood pressure, and left ventricular function. The methanol extract of T. cucumerina significantly decreased LDH and CK-MB, reduced ST, QT interval and QRS complex, increased heart rate, restored blood pressure, and left ventricular function. Doxorubicin caused liver and kidney necrosis, cellular infiltration, and vascular changes that indicated injury.

CONCLUSION

T. cucumerina (1000 mg/kg) reduced the severity of doxorubicin-induced cardiac damage especially in heart. It is concluded that doxorubicin-induced cardiotoxicity is reduced by pretreatment with methanol extract of fruit of T. cucumerina.

Chemotherapy-induced weakness and fatigue in skeletal muscle: the role of oxidative stress

SIGNIFICANCE

Fatigue is one of the most common symptoms of cancer and its treatment, manifested in the clinic through weakness and exercise intolerance. These side effects not only compromise patient's quality of life (QOL), but also diminish physical activity, resulting in limited treatment and increased morbidity.

RECENT ADVANCES

Oxidative stress, mediated by cancer or chemotherapeutic agents, is an underlying mechanism of the drug-induced toxicity. Nontargeted tissues, such as striated muscle, are severely affected by oxidative stress during chemotherapy, leading to toxicity and dysfunction.

CRITICAL ISSUES

These findings highlight the importance of investigating clinically applicable interventions to alleviate the debilitating side effects. This article discusses the clinically available chemotherapy drugs that cause fatigue and oxidative stress in cancer patients, with an in-depth focus on the anthracycline doxorubicin. Doxorubicin, an effective anticancer drug, is a primary example of how chemotherapeutic agents disrupt striated muscle function through oxidative stress.

FUTURE DIRECTIONS

Further research investigating antioxidants could provide relief for cancer patients from debilitating muscle weakness, leading to improved quality of life.

Global gene expression profiles of MT knockout and wild-type mice in the condition of doxorubicin-induced cardiomyopathy

Increasing evidence from in vivo and in vitro studies has indicated that MT exerts protective effects against DOX-induced cardiotoxicity; however the underlying precise mechanisms still remain an enigma. Therefore, the present study was designed using MT knockout mice in concert with genomic approaches to explore the possible molecular and cellular mechanisms in terms of the genetic network changes. MT-I/II null (MT⁻/⁻) mice and corresponding wild-type mice (MT+/+) were administrated with a single dose of DOX (15 mg/kg, i.p.) or equal volume of saline. Animals were sacrificed on the 4th day after DOX administration and samples were collected for further analyses. Global gene expression profiles of cardiac mRNA from two genotype mice revealed that 381 characteristically MT-responsive genes were identified between MT+/+ mice and MT⁻/⁻ mice in response to DOX, including fos, ucp3, car3, atf3, map3k6, etc. Functional analysis implied MAPK signaling pathway, p53 signaling pathway, Jak-STAT signaling pathway, PPAR signaling pathway, Wnt signaling pathway, etc. might be involved to mediate the protection of DOX cardiomyopathy by MT. Results from the present study not only validated the previously reported possible mechanisms of MT protection against DOX toxicity, but also provided new clues into the molecular mechanisms involved in this process.

The ubiquitous role of zinc in health and disease

OBJECTIVE

To review zinc physiology and pathophysiology and the importance of zinc toxicity and deficiency in veterinary patients.

DATA SOURCES

A review of human and veterinary medical literature.

HUMAN DATA SYNTHESIS

There is a significant amount of original research in humans and animals on the role of zinc in multiple organ systems. There is also significant data available on human patients with zinc abnormalities.

VETERINARY DATA SYNTHESIS

Zinc deficiency has been studied in dogs with genetic disease and dietary deficiency leading to dermatological disease and immune deficiency. Zinc toxicity has been described after ingestion of metallic foreign bodies containing zinc.

CONCLUSIONS

Historically, the role of zinc in health and disease has been studied through patients with toxicity or severe deficiency with obvious clinical signs. As the ubiquitous contribution of zinc to structure and function in biological systems was discovered, clinically significant but subtle deficiency states have been revealed. In human medicine, mild zinc deficiencies are currently thought to cause chronic metabolic derangement leading to or exacerbating immune deficiency, gastrointestinal problems, endocrine disorders, neurologic dysfunction, cancer, accelerated aging, degenerative disease, and more. Determining the causal relationships between mild zinc deficiency and concurrent disease is complicated by the lack of sensitive or specific tests for zinc deficiency. The prevalence of zinc deficiency and its contribution to disease in veterinary patients is not well known. Continued research is warranted to develop more sensitive and specific tests to assess zinc status, to determine which patients are at risk for deficiency, and to optimize supplementation in health and disease.

Tumor detection and elimination by a targeted gallium corrole

Sulfonated gallium(III) corroles are intensely fluorescent macrocyclic compounds that spontaneously assemble with carrier proteins to undergo cell entry. We report in vivo imaging and therapeutic efficacy of a tumor-targeted corrole noncovalently assembled with a heregulin-modified protein directed at the human epidermal growth factor receptor (HER). Systemic delivery of this protein-corrole complex results in tumor accumulation, which can be visualized in vivo owing to intensely red corrole fluorescence. Targeted delivery in vivo leads to tumor cell death while normal tissue is spared. These findings contrast with the effects of doxorubicin, which can elicit cardiac damage during therapy and required direct intratumoral injection to yield similar levels of tumor shrinkage compared with the systemically delivered corrole. The targeted complex ablated tumors at >5 times a lower dose than untargeted systemic doxorubicin, and the corrole did not damage heart tissue. Complexes remained intact in serum and the carrier protein elicited no detectable immunogenicity. The sulfonated gallium(III) corrole functions both for tumor detection and intervention with safety and targeting advantages over standard chemotherapeutic agents.

Recent advances in protection against doxorubicin-induced toxicity

Anthracycline antibiotics are among the most effective and commonly used anticancer drugs. Unfortunately, their clinical use is restricted by dose-dependent toxicity. Doxorubicin is an anthracycline antibiotic and cytotoxic (antineoplastic) agent. It is commonly used against ovarian, breast, lung, uterine and cervical cancers, Hodgkin's disease, soft tissue and primary bone sarcomas, as well against in several other cancer types. It has been shown that free radicals are involved in doxorubicin-induced toxicity. Doxorubicin causes the generation of free radicals and the induction of oxidative stress, associated with cellular injury. This review illustrates recent applications of different natural products, drugs, drug delivery systems, and approaches for protection against doxorubicin-induced toxicity (2006-present).