Identification of protein targets underlying dietary nitrate-induced protection against doxorubicin cardiotoxicity

Enduring metabolic modulation in the cardiac tissue of elderly CD-1 mice two months post mitoxantrone treatment

Mitoxantrone (MTX) is a therapeutic agent used in the treatment of solid tumors and multiple sclerosis, recognized for its cardiotoxicity, with underlying molecular mechanisms not fully disclosed. The cardiotoxicity is influenced by risk factors, including age. Our study intended to assess the molecular effect of MTX on the cardiac muscle of old male CD-1 mice. Mice aged 19 months received a total cumulative dose of 4.5 mg/kg of MTX (MTX group) or saline solution (CTRL group). Two months post treatment, blood was collected, animals sacrificed, and the heart removed. MTX caused structural cardiac changes, which were accompanied by extracellular matrix remodeling, as indicated by the increased ratio between matrix metallopeptidase 2 and metalloproteinase inhibitor 2. At the metabolic level, decreased glycerol levels were found, together with a trend towards increased content of the electron transfer flavoprotein dehydrogenase. In contrast, lower glycolysis, given by the decreased content of glucose transporter GLUT4 and phosphofructokinase, seemed to occur. The findings suggest higher reliance on fatty acids oxidation, despite no major remodeling occurring at the mitochondrial level. Furthermore, the levels of glutamine and other amino acids (although to a lesser extent) were decreased, which aligns with decreased content of the E3 ubiquitin-protein ligase Atrogin-1, suggesting a decrease in proteolysis. As far as we know, this was the first study made in old mice with a clinically relevant dose of MTX, evaluating its long-term cardiac effects. Even two months after MTX exposure, changes in metabolic fingerprint occurred, highlighting enduring cardiac effects that may require clinical vigilance.

Insights on the molecular targets of cardiotoxicity induced by anticancer drugs: A systematic review based on proteomic findings

Several anticancer agents have been associated with cardiac toxic effects. The currently proposed mechanisms to explain cardiotoxicity differ among anticancer agents, but in fact, the specific modulation is not completely elucidated. Thus, this systematic review aims to provide an integrative perspective of the molecular mechanisms underlying the toxicity of anticancer agents on heart muscle while using a high-throughput technology, mass spectrometry (MS)-based proteomics. A literature search using PubMed database led to the selection of 27 studies, of which 13 reported results exclusively on animal models, 13 on cardiomyocyte-derived cell lines and only one included both animal and a cardiomyocyte line. The reported anticancer agents were the proteasome inhibitor carfilzomib, the anthracyclines daunorubicin, doxorubicin, epirubicin and idarubicin, the antimicrotubule agent docetaxel, the alkylating agent melphalan, the anthracenedione mitoxantrone, the tyrosine kinase inhibitors (TKIs) erlotinib, lapatinib, sorafenib and sunitinib, and the monoclonal antibody trastuzumab. Regarding the MS-based proteomic approaches, electrophoretic separation using two-dimensional (2D) gels coupled with tandem MS (MS/MS) and liquid chromatography-MS/MS (LC-MS/MS) were the most common. Overall, the studies highlighted 1826 differentially expressed proteins across 116 biological processes. Most of them were grouped in larger processes and critically analyzed in the present review. The selection of studies using proteomics on heart muscle allowed to obtain information about the anticancer therapy-induced modulation of numerous proteins in this tissue and to establish connections that have been disregarded in other studies. This systematic review provides interesting points for a comprehensive understanding of the cellular cardiotoxicity mechanisms of different anticancer drugs.

Chemotherapy-Induced Myopathy: The Dark Side of the Cachexia Sphere

Simple Summary

In addition to cancer-related factors, anti-cancer chemotherapy treatment can drive life-threatening body wasting in a syndrome known as cachexia. Emerging evidence has described the impact of several key chemotherapeutic agents on skeletal muscle in particular, and the mechanisms are gradually being unravelled. Despite this evidence, there remains very little research regarding therapeutic strategies to protect muscle during anti-cancer treatment and current global grand challenges focused on deciphering the cachexia conundrum fail to consider this aspect—chemotherapy-induced myopathy remains very much on the dark side of the cachexia sphere. This review explores the impact and mechanisms of, and current investigative strategies to protect against, chemotherapy-induced myopathy to illuminate this serious issue.

Abstract

Cancer cachexia is a debilitating multi-factorial wasting syndrome characterised by severe skeletal muscle wasting and dysfunction (i.e., myopathy). In the oncology setting, cachexia arises from synergistic insults from both cancer–host interactions and chemotherapy-related toxicity. The majority of studies have surrounded the cancer–host interaction side of cancer cachexia, often overlooking the capability of chemotherapy to induce cachectic myopathy. Accumulating evidence in experimental models of cachexia suggests that some chemotherapeutic agents rapidly induce cachectic myopathy, although the underlying mechanisms responsible vary between agents. Importantly, we highlight the capacity of specific chemotherapeutic agents to induce cachectic myopathy, as not all chemotherapies have been evaluated for cachexia-inducing properties—alone or in clinically compatible regimens. Furthermore, we discuss the experimental evidence surrounding therapeutic strategies that have been evaluated in chemotherapy-induced cachexia models, with particular focus on exercise interventions and adjuvant therapeutic candidates targeted at the mitochondria.

Exploring the aging effect of the anticancer drugs doxorubicin and mitoxantrone on cardiac mitochondrial proteome using a murine model

Current cancer therapies are successfully increasing the lifespan of cancer patients. Nevertheless, cardiotoxicity is a serious chemotherapy-induced adverse side effect. Doxorubicin (DOX) and mitoxantrone (MTX) are cardiotoxic anticancer agents, whose toxicological mechanisms are still to be identified. This study focused on DOX and MTX's cardiac mitochondrial damage and their molecular mechanisms. As a hypothesis, we also sought to compare the cardiac modulation caused by 9 mg/kg of DOX or 6 mg/kg of MTX in young adult mice (3 months old) with old control mice (aged control, 18-20 months old) to determine if DOX- and MTX-induced damage had common links with the aging process. Cardiac homogenates and enriched mitochondrial fractions were prepared from treated and control animals and analyzed by immunoblotting and enzymatic assays. Enriched mitochondrial fractions were also characterized by mass spectrometry-based proteomics. Data obtained showed a decrease in mitochondrial density in young adults treated with DOX or MTX and aged control, as assessed by citrate synthase (CS) activity. Furthermore, aged control had increased expression of the peroxisome proliferator-activated receptor γ coactivator 1 α (PGC1α) and manganese superoxide dismutase (MnSOD). Regarding the enriched mitochondrial fractions, DOX and MTX led to downregulation of proteins related to oxidative phosphorylation, fatty acid oxidation, amino acid metabolic process, and tricarboxylic acid cycle. MTX had a greater impact on malate dehydrogenase (MDH2) and pyruvate dehydrogenase E1 component subunit α (PDHA1). No significant proteomic changes were observed in the enriched mitochondrial fractions of aged control when compared to young control. To conclude, DOX and MTX promoted changes in several mitochondrial-related proteins in young adult mice, but none resembling the aged phenotype.

Sodium nitrate co-supplementation does not exacerbate low dose metronomic doxorubicin-induced cachexia in healthy mice

The purpose of this study was to determine whether (1) sodium nitrate (SN) treatment progressed or alleviated doxorubicin (DOX)-induced cachexia and muscle wasting; and (2) if a more-clinically relevant low-dose metronomic (LDM) DOX treatment regimen compared to the high dosage bolus commonly used in animal research, was sufficient to induce cachexia in mice. Six-week old male Balb/C mice (n = 16) were treated with three intraperitoneal injections of either vehicle (0.9% NaCl; VEH) or DOX (4 mg/kg) over one week. To test the hypothesis that sodium nitrate treatment could protect against DOX-induced symptomology, a group of mice (n = 8) were treated with 1 mM NaNO₃ in drinking water during DOX (4 mg/kg) treatment (DOX + SN). Body composition indices were assessed using echoMRI scanning, whilst physical and metabolic activity were assessed via indirect calorimetry, before and after the treatment regimen. Skeletal and cardiac muscles were excised to investigate histological and molecular parameters. LDM DOX treatment induced cachexia with significant impacts on both body and lean mass, and fatigue/malaise (i.e. it reduced voluntary wheel running and energy expenditure) that was associated with oxidative/nitrostative stress sufficient to induce the molecular cytotoxic stress regulator, nuclear factor erythroid-2-related factor 2 (NRF-2). SN co-treatment afforded no therapeutic potential, nor did it promote the wasting of lean tissue. Our data re-affirm a cardioprotective effect for SN against DOX-induced collagen deposition. In our mouse model, SN protected against LDM DOX-induced cardiac fibrosis but had no effect on cachexia at the conclusion of the regimen.

Hydrogen Sulfide Therapy Suppresses Cofilin-2 and Attenuates Ischemic Heart Failure in a Mouse Model of Myocardial Infarction

AIMS

Hydrogen sulfide (H2S) protects against ischemic and inflammatory injury following myocardial ischemia via induction of microRNA (miR)-21. We sought to determine whether H2S attenuates ischemic heart failure with reduced ejection fraction (HFrEF) and interrogate the role of cofilin-2, a target of miR-21, in this protective process.

METHODS AND RESULTS

Adult male mice underwent myocardial infarction (MI) by coronary artery ligation after baseline echocardiography. Following MI, mice were treated with Na2S (100 μg/kg/day; intraperitoneal [IP]) or saline up to 28 days. End-diastolic pressure, measured by Millar catheter, was significantly increased (P < .05 vs sham) at 3 days post-MI in the saline group, which was attenuated with Na2S. Left ventricular (LV) fractional shortening decreased significantly at 28 days post-MI in the saline group but was preserved with Na2S and LV infarct scar size was smaller in Na2S group as compared to control. Apoptotic signaling, measured by Bcl-2/Bax ratio, was significantly increased in the saline group but was mitigated with Na2S. Survival rate was 2-fold higher in Na2S group compared to saline control (P < .05). Proteomic analysis and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (TOF)/TOF tandem mass spectrometry identified significant changes in proapoptotic cofilin-2 expression, a specific target of miR-21, between saline- and sodium sulfide -treated mice at 28 days post-MI. Western blot analysis confirmed a significant increase in cofilin-2 after MI, which was suppressed with Na2S treatment. Chronic Na2S treatment also attenuated inflammasome formation and activation leading to reduction of maladaptive signaling.

CONCLUSION

Na2S treatment after MI preserves LV function and improves survival through attenuation of inflammasome-mediated adverse remodeling. We propose H2S donors as promising therapeutic tools for ischemic HFrEF.

Potential Therapeutic Strategies for Hypertension-Exacerbated Cardiotoxicity of Anticancer Drugs

Despite their recognized cardiotoxic effects, anthracyclines remain an essential component in many anticancer regimens due to their superior antitumor efficacy. Epidemiologic data revealed that about one-third of cancer patients have hypertension, which is the most common comorbidity in cancer registries. The purpose of this review is to assess whether anthracycline chemotherapy exacerbates cardiotoxicity in patients with hypertension. A link between hypertension comorbidity and anthracycline-induced cardiotoxicity (AIC) was first suggested in 1979. Subsequent preclinical and clinical studies have supported the notion that hypertension is a major risk factor for AIC, along with the cumulative anthracycline dosage. There are several common or overlapping pathological mechanisms in AIC and hypertension, such as oxidative stress. Current evidence supports the utility of cardioprotective modalities as adjunct treatment prior to and during anthracycline chemotherapy. Several promising cardioprotective approaches against AIC pathologies include dexrazoxane, early hypertension management, and dietary supplementation of nitrate with beetroot juice or other medicinal botanical derivatives (e.g., visnagin and Danshen), which have both antihypertensive and anti-AIC properties. Future research is warranted to further elucidate the mechanisms of hypertension and AIC comorbidity and to conduct well-controlled clinical trials for identifying effective clinical strategies to improve long-term prognoses in this subgroup of cancer patients.

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.

Hydrogen sulfide attenuates doxorubicin-induced cardiotoxicity by inhibiting the expression of peroxiredoxin III in H9c2 cells

Doxorubicin (DOX) is a widely used chemotherapeutic agent, which can give rise to severe cardiotoxicity, limiting its clinical use. Preliminary evidence suggests that hydrogen sulfide (H2S) may exert protective effects on DOX‑induced cardiotoxicity. Therefore, the aim of the present study was to investigate whether peroxiredoxin III is involved in the cardioprotection of H2S against DOX‑induced cardiotoxicity. The results demonstrated that DOX not only markedly induced injuries, including cytotoxicity and apoptosis, it also increased the expression levels of peroxiredoxin III. Notably, pretreatment with sodium hydrosulfide significantly attenuated the DOX‑induced decrease in cell viability and increase in apoptosis, and also reversed the increased expression levels of peroxiredoxin III in H9c2 cardiomyocytes. In addition, pretreatment of the H9c2 cells with N‑acetyl‑L‑cysteine, a scavenger of reactive oxygen species, prior to exposure to DOX markedly decreased the expression levels of peroxiredoxin III. In conclusion, the results of the present study suggested that exogenous H2S attenuates DOX‑induced cardiotoxicity by inhibiting the expression of peroxiredoxin III in H9c2 cells. In the present study, the apoptosis of H9c2 cardiomyocytes was assessed using an methyl thiazolyl tetrazolium assay and Hoechst staining. The levels of Prx III and cystathionine-γ-lyase were examined by western blotting.

Upregulation of peroxiredoxin III in doxorubicin-induced cytotoxicity and the FoxO3a-dependent expression in H9c2 cardiac cells

Doxorubicin (DOX) is an efficient drug used in cancer therapy; however, it produces reactive oxygen species (ROS) that induce severe cytotoxicity, limiting its clinical application. The aim of the present study was to investigate the role of peroxiredoxin III (Prx III) in DOX-induced H9c2 cell injuries. Following DOX treatment, the expression of phosphorylated-FoxO3a (p-FoxO3a) was decreased and Prx III expression was increased in H9c2 cells. In order to detect whether oxidative stress was involved in the induction of Prx III expression by FoxO3a, exogenous H₂O₂ was used to induce oxidative stress in the H9c2 cells. Apoptosis of H9c2 cardiomyocytes was assessed using methyl thiazolyl tetrazolium assay and Hoechst staining. The levels of Prx III and p-FoxO3a were evaluated using western blot analysis. As expected, H₂O₂ was found to mimic the effect of DOX, decreasing the expression of p-FoxO3a and increasing the expression of Prx III. In addition, the study evaluated whether the transcription factor FoxO3a was essential for the expression of Prx III. Pretreatment of H9c2 cells with N-acetyl-L-cysteine (NAC), a scavenger of ROS, prior to exposure to DOX dramatically increased the phosphorylation of FoxO3a and led to a marked reduction in Prx III expression in the H9c2 cells. In conclusion, the results of the current study suggest that FoxO3a mediates the expression of Prx III in DOX-induced injuries.

Beetroot juice reduces infarct size and improves cardiac function following ischemia-reperfusion injury: Possible involvement of endogenous H2S

Ingestion of high dietary nitrate in the form of beetroot juice (BRJ) has been shown to exert antihypertensive effects in humans through increasing cyclic guanosine monophosphate (cGMP) levels. Since enhanced cGMP protects against myocardial ischemia-reperfusion (I/R) injury through upregulation of hydrogen sulfide (H2S), we tested the hypothesis that BRJ protects against I/R injury via H2S. Adult male CD-1 mice received either regular drinking water or those dissolved with BRJ powder (10 g/L, containing ∼ 0.7 mM nitrate). Seven days later, the hearts were explanted for molecular analyses. Subsets of mice were subjected to I/R injury by occlusion of the left coronary artery for 30 min and reperfusion for 24 h. A specific inhibitor of H2S producing enzyme--cystathionine-γ-lyase (CSE), DL-propargylglycine (PAG, 50 mg/kg) was given i.p. 30 min before ischemia. Myocardial infarct size was significantly reduced in BRJ-fed mice (15.8 ± 3.2%) versus controls (46.5 ± 3.5%, mean ± standard error [SE], n = 6/group, P < .05). PAG completely blocked the infarct-limiting effect of BRJ. Moreover, BRJ significantly preserved ventricular function following I/R. Myocardial levels of H2S and its putative protein target--vascular endothelial growth factor receptor 2 (VEGFR2) were significantly increased by BRJ intake, whereas CSE mRNA and protein content did not change. Interestingly, the BRJ-induced cardioprotection was not associated with elevated blood nitrate-nitrite levels following I/R nor induction of cardiac peroxiredoxin 5, a mitochondrial antioxidant enzyme previously linked to nitrate-induced cardioprotection. We conclude that BRJ ingestion protects against post-I/R myocardial infarction and ventricular dysfunction possibly through CSE-mediated endogenous H2S generation. BRJ could be a promising natural and inexpensive nutraceutical supplement to reduce cardiac I/R injury in patients.

Inorganic nitrite supplementation for healthy arterial aging

Aging is the major risk factor for cardiovascular diseases (CVD). This is attributable primarily to adverse changes in arteries, notably, increases in large elastic artery stiffness and endothelial dysfunction mediated by inadequate concentrations of the vascular-protective molecule, nitric oxide (NO), and higher levels of oxidative stress and inflammation. Inorganic nitrite is a promising precursor molecule for augmenting circulating and tissue NO bioavailability because it requires only a one-step reduction to NO. Nitrite also acts as an independent signaling molecule, exerting many of the effects previously attributed to NO. Results of recent studies indicate that nitrite may be effective in the treatment of vascular aging. In old mice, short-term oral sodium nitrite supplementation reduces aortic pulse wave velocity, the gold-standard measure of large elastic artery stiffness, and ameliorates endothelial dysfunction, as indicated by normalization of NO-mediated endothelium-dependent dilation. These improvements in age-related vascular dysfunction with nitrite are mediated by reductions in oxidative stress and inflammation, and may be linked to increases in mitochondrial biogenesis and health. Increasing nitrite levels via dietary intake of nitrate appears to have similarly beneficial effects in many of the same physiological and clinical settings. Several clinical trials are being performed to determine the broad therapeutic potential of increasing nitrite bioavailability on human health and disease, including studies related to vascular aging. In summary, inorganic nitrite, as well as dietary nitrate supplementation, represents a promising therapy for treatment of arterial aging and prevention of age-associated CVD in humans.

Mammalian target of rapamycin (mTOR) inhibition with rapamycin improves cardiac function in type 2 diabetic mice: potential role of attenuated oxidative stress and altered contractile protein expression

Elevated mammalian target of rapamycin (mTOR) signaling contributes to the pathogenesis of diabetes, with increased morbidity and mortality, mainly because of cardiovascular complications. Because mTOR inhibition with rapamycin protects against ischemia/reperfusion injury, we hypothesized that rapamycin would prevent cardiac dysfunction associated with type 2 diabetes (T2D). We also investigated the possible mechanisms and novel protein targets involved in rapamycin-induced preservation of cardiac function in T2D mice. Adult male leptin receptor null, homozygous db/db, or wild type mice were treated daily for 28 days with vehicle (5% DMSO) or rapamycin (0.25 mg/kg, intraperitoneally). Cardiac function was monitored by echocardiography, and protein targets were identified by proteomics analysis. Rapamycin treatment significantly reduced body weight, heart weight, plasma glucose, triglyceride, and insulin levels in db/db mice. Fractional shortening was improved by rapamycin treatment in db/db mice. Oxidative stress as measured by glutathione levels and lipid peroxidation was significantly reduced in rapamycin-treated db/db hearts. Rapamycin blocked the enhanced phosphorylation of mTOR and S6, but not AKT in db/db hearts. Proteomic (by two-dimensional gel and mass spectrometry) and Western blot analyses identified significant changes in several cytoskeletal/contractile proteins (myosin light chain MLY2, myosin heavy chain 6, myosin-binding protein C), glucose metabolism proteins (pyruvate dehydrogenase E1, PYGB, Pgm2), and antioxidant proteins (peroxiredoxin 5, ferritin heavy chain 1) following rapamycin treatment in db/db heart. These results show that chronic rapamycin treatment prevents cardiac dysfunction in T2D mice, possibly through attenuation of oxidative stress and alteration of antioxidants and contractile as well as glucose metabolic protein expression.

Identification of the Transmembrane Glucose Regulated Protein 78 as a Biomarker for the Brain Cancer Glioblastoma Multiforme by Gene Expression and Proteomic Studies

The prognosis of patients with Glioblastoma Multiforme (GBM), the most malignant adult glial brain tumor, remains poor in spite of advances in treatment procedures, including surgical resection, irradiation and chemotherapy. Genetic heterogeneity of GBM warrants extensive studies to gain a thorough understanding of the biology of this tumor. While there have been several studies of global transcript profiling of glioma with the identification of gene signatures for diagnosis and disease management, translation into clinics is yet to happen. In the present study, we report a novel proteomic approach by using two-dimensional difference gel electrophoresis (2D-DIGE) followed by spot picking and analysis of proteins/peptides by Mass Spectrometry. We report Glucose Regulated Protein 78 (GRP78) as a differentially expressed protein in the GBM cell line compared to human normal Astrocyte cells.

In addition to proteomic studies, we performed microarray analysis which further confirmed up regulation of GRP78 in GBM cells compared to human normal Astrocyte cells.

GRP78 has long been recognized as a molecular chaperone in the endoplasmic reticulum (ER) and can be induced by the ER stress response. Besides its location in the ER, GRP78 has been found in cell plasma membrane, cytoplasm, mitochondria, nucleus and other cellular secretions. GRP78 is implicated in tumor cell proliferation, apoptosis resistance, immune escape, metastasis and angiogenesis, and its elevated expression usually correlates with a variety of tumor micro environmental stresses, including hypoxia, glucose deprivation, lactic acidosis and inflammatory response. GRP78 protein acts as a centrally located sensor of stress, which senses and facilitates the adaptation to the tumor microenvironment.

Our findings showed differential expression of this gene in brain cancer GBM and thus confirm similarities in findings in existing transcriptional and translational studies. Thus, these findings could be of further importance for diagnostic, therapeutic and prognostic approaches for dealing with this highly malignant cancer.

Type 2 diabetic obese db/db mice are refractory to myocardial ischaemic post-conditioning in vivo: potential role for Hsp20, F1-ATPase δ and Echs1

Ischaemic post-conditioning (PostC) is a clinically relevant cardioprotective modality that has been confirmed in many species including human. It remains unknown if PostC can still protect heart in Type 2 diabetes, a rapidly growing disease in the world. This study investigated the efficacy of PostC in the leptin receptor–deficient db/db mice, which possess Type 2 diabetic characteristics including obesity, hyperglycaemia and hyperleptinaemia. Adult male C57BL/6J wild-type (WT) and db/db mice were anaesthetized, mechanically ventilated and subjected to left coronary artery occlusion for 30 min. followed by 24 hrs of reperfusion. For the PostC groups, the hearts underwent six cycles of 10 sec. of reperfusion and 10 sec. of re-occlusion at the onset of reperfusion. The mice were sacrificed at the end of 24 hrs reperfusion for infarct size measurement. PostC significantly reduced infarct size in WT mice (n = 6/group; P < 0.05), but not in the db/db mice. To identify alterations in protein expression by PostC, proteomic analyses were performed in the heart samples using two-dimensional differential in-gel electrophoresis with three CyDye labelling, followed by mass spectrometry. The results show that mitochondrial proteins (F₁-ATPase γ and Echs1) were down-regulated by PostC in WT heart. Such change was absent in the db/db heart. On the other hand, PostC reduced Hsp20 in the diabetic heart. In summary, PostC fails to protect Type 2 diabetic mice against ischaemia-reperfusion injury. The potential protein targets for the loss of PostC may include F₁-ATPase γ, Echs1 and Hsp20 that could regulate cellular ATP consumption/production and defense response to ischaemic stress.

Search for a diagnostic/prognostic biomarker for the brain cancer glioblastoma multiforme by 2D-DIGE-MS technique

The prognosis of patients with glioblastoma multiforme, the most malignant adult glial brain tumor, remains poor in spite of advances in treatment procedures, including surgical resection, irradiation, and chemotherapy. Genetic heterogeneity of glioblastoma warrants extensive studies to gain a thorough understanding of the biology of this tumor. While there have been several studies of global transcript profiling of glioma with the identification of gene signatures for diagnosis and disease management, translation into clinics is yet to happen. In the present study, we report a novel proteomic approach by using two-dimensional difference gel electrophoresis followed by spot picking and analysis of proteins/peptides by Mass spectrometry. We report at least ten different novel proteins/peptides as identified by this technique which are differentially expressed in this cancer and could be of further importance for diagnostic, therapeutic, and prognostic approaches.

Dietary inorganic nitrate alleviates doxorubicin cardiotoxicity: mechanisms and implications

Doxorubicin (DOX) is one of the most powerful and widely prescribed chemotherapeutic agents to treat divergent human cancers. However, the clinical use of DOX is restricted due to its severe cardiotoxic side-effects. There has been ongoing search for cardioprotectants against DOX toxicity. Inorganic nitrate has emerged as a bioactive compound that can be reduced into nitrite and nitric oxide in vivo and in turn plays a therapeutic role in diseases associated with nitric oxide insufficiency or dysregulation. In this review, we describe a novel concept of using dietary supplementation of inorganic nitrate to reduce DOX-induced cardiac cellular damage and dysfunction, based on our recent promising studies in a mouse model of DOX cardiotoxicity. Our data show that chronic oral ingestion of sodium nitrate, at a dose equivalent to ~400% of the Acceptable Daily Intake of the World Health Organization, alleviated DOX-induced left ventricular dysfunction and mitochondrial respiratory chain damage. Such cardioprotective effects were associated with reduction of cardiomyocyte necrosis/apoptosis, tissue lipid peroxidation, and mitochondrial H(2)O(2) generation following DOX treatment. Furthermore, proteomic studies revealed enhanced cardiac expression of mitochondrial antioxidant enzyme - peroxiredoxin 5 in the nitrate-treated animals. These studies suggest that inorganic nitrate could be an inexpensive therapeutic agent for long-term oral administration in preventing DOX-induced cardiac toxicity and myopathy during the prolonged pathological process. Future clinical trials in the cancer patients undergoing DOX chemotherapy are warranted to translate these experimental findings into an effective new therapy in preventing the DOX-induced cardiomyopathy.

Chronic treatment with long acting phosphodiesterase-5 inhibitor tadalafil alters proteomic changes associated with cytoskeletal rearrangement and redox regulation in Type 2 diabetic hearts

Diabetic patients are prone to metabolic perturbations that progressively contribute to structural, functional and proteomic alterations in the myocardium. Phosphodiesterase-5 (PDE-5) inhibitors exhibit cardioprotective effects against ischemic/reperfusion injury, however the effects of chronic administration of PDE-5 inhibitors, particularly under diabetic conditions, remain unknown. Hence, the present study was designed to identify novel protein targets related to long-acting PDE-5 inhibitor tadalafil-induced cardioprotection in diabetes. Using two-dimensional differential in-gel electrophoresis with 3 CyDye labeling and MALDI-TOF/TOF tandem mass spectrometry we identified alterations in the expressions of cardiac proteins in diabetic db/db mice treated with tadalafil. Tadalafil reversed the coordinated alterations of cytoskeletal/contractile proteins such as myosin light chain (MLY) 2 and 4, myosin heavy chain α and myosin-binding protein C which contributes to contractile dysfunction. The expression of intermediate filament protein vimentin and extra-cellular matrix proteins like cysteine and glycine rich protein-3 and collagen type VI α were upregulated in db/db mice indicating cardiac remodeling in diabetes. These detrimental proteomic alterations were reflected in cardiac function which were reversed in tadalafil treated mice. Tadalafil also enhanced antioxidant enzyme glutathione S-transferase Kappa-1 (GSKT-1) and downregulated redox regulatory chaperones like heat shock protein 8 (HSPA8), and 75 kD glucose regulatory protein (75GRP). Furthermore, tadalafil treatment significantly attenuated GSSG/GSH ratio and improved the metabolic status of db/db mice. Chronic treatment with tadalafil in db/db mice modulates proteins involved in cytoskeletal rearrangement and redox signaling of the heart, which may explain the beneficial effects of PDE-5 inhibition in diabetes.