Phospholipase C-delta1 is a critical target for tumor necrosis factor receptor-mediated protection against adriamycin-induced cardiac injury

The Role of Oxidative Stress in Cardiac Disease: From Physiological Response to Injury Factor

Reactive oxygen species (ROS) are highly reactive chemical species containing oxygen, controlled by both enzymatic and nonenzymatic antioxidant defense systems. In the heart, ROS play an important role in cell homeostasis, by modulating cell proliferation, differentiation, and excitation-contraction coupling. Oxidative stress occurs when ROS production exceeds the buffering capacity of the antioxidant defense systems, leading to cellular and molecular abnormalities, ultimately resulting in cardiac dysfunction. In this review, we will discuss the physiological sources of ROS in the heart, the mechanisms of oxidative stress-related myocardial injury, and the implications of experimental studies and clinical trials with antioxidant therapies in cardiovascular diseases.

Noteworthy prognostic value of phospholipase C delta genes in early stage pancreatic ductal adenocarcinoma patients after pancreaticoduodenectomy and potential molecular mechanisms

The purpose of this investigation was to explore the prognostic value of phospholipase C delta (PLCD) genes in early stage pancreatic ductal adenocarcinoma (PDAC) and its potential molecular mechanisms. The prognostic value of PLCD genes in early stage PDAC was assessed using the Kaplan-Meier method and multivariate Cox proportional hazards regression model. Genome-wide correlation analysis was performed on PLCD3 to identify the highly correlated genes in the transcriptome. Then, PLCD3 and these correlated genes together underwent a bioinformatics analysis to elucidate the potential molecular biological functions of PLCD3 in PDAC. PLCD1 and PLCD3 are significantly overexpressed in PDAC. In PDAC patients, PLCD3 is overexpressed in certain groups of people with a history of alcoholism (P = .032). High expression of PLCD3 was found to be associated with lower overall survival (OS) of patients with early stage PDAC (P = .020; adjusted P = .016). A combination of PLCD3 and clinical variables was able to better predict the outcome of patients with early stage PDAC. These clinical variables are histological grade (P = .001; adjusted P = .001), targeted molecular therapy (P < .001; adjusted P < .001), radiation therapy (P = .002; adjusted P = .039), and residual resection (P = .001; adjusted P = .002). The bioinformatics analysis revealed that PLCD3 is associated with angiogenesis, intracellular signal transduction, and regulation of cell proliferation. In conclusion, PLCD3 may be a potential prognostic biomarker for early stage PDAC.

The triangle of death of neurons: Oxidative damage, mitochondrial dysfunction, and loss of choline-containing biomolecules in brains of mice treated with doxorubicin. Advanced insights into mechanisms of chemotherapy induced cognitive impairment ("chemobrain") involving TNF-α

Cancer treatments are developing fast and the number of cancer survivors could arise to 20 million in United State by 2025. However, a large fraction of cancer survivors demonstrate cognitive dysfunction and associated decreased quality of life both shortly, and often long-term, after chemotherapy treatment. The etiologies of chemotherapy induced cognitive impairment (CICI) are complicated, made more so by the fact that many anti-cancer drugs cannot cross the blood-brain barrier (BBB). Multiple related factors and confounders lead to difficulties in determining the underlying mechanisms. Chemotherapy induced, oxidative stress-mediated tumor necrosis factor-alpha (TNF-α) elevation was considered as one of the main candidate mechanisms underlying CICI. Doxorubicin (Dox) is a prototypical reactive oxygen species (ROS)-generating chemotherapeutic agent used to treat solid tumors and lymphomas as part of multi-drug chemotherapeutic regimens. We previously reported that peripheral Dox-administration leads to plasma protein damage and elevation of TNF-α in plasma and brain of mice. In the present study, we used TNF-α null (TNFKO) mice to investigate the role of TNF-α in Dox-induced, oxidative stress-mediated alterations in brain. We report that Dox-induced oxidative stress in brain is ameliorated and brain mitochondrial function assessed by the Seahorse-determined oxygen consumption rate (OCR) is preserved in brains of TNFKO mice. Further, we show that Dox-decreased the level of hippocampal choline-containing compounds and brain phospholipases activity are partially protected in TNFKO group in MRS study. Our results provide strong evidence that Dox-targeted mitochondrial damage and levels of brain choline-containing metabolites, as well as phospholipases changes decreased in the CNS are associated with oxidative stress mediated by TNF-α. These results are consistent with the notion that oxidative stress and elevated TNF-α in brain underlie the damage to mitochondria and other pathological changes that lead to CICI. The results are discussed with reference to our identifying a potential therapeutic target to protect against cognitive problems after chemotherapy.

Chemotherapy-Induced Cardiotoxicity: Overview of the Roles of Oxidative Stress

Chemotherapy-induced cardiotoxicity is a serious complication that poses a serious threat to life and limits the clinical use of various chemotherapeutic agents, particularly the anthracyclines. Understanding molecular mechanisms of chemotherapy-induced cardiotoxicity is a key to effective preventive strategies and improved chemotherapy regimen. Although no reliable and effective preventive treatment has become available, numerous evidence demonstrates that chemotherapy-induced cardiotoxicity involves the generation of reactive oxygen species (ROS). This review provides an overview of the roles of oxidative stress in chemotherapy-induced cardiotoxicity using doxorubicin, which is one of the most effective chemotherapeutic agents against a wide range of cancers, as an example. Current understanding in the molecular mechanisms of ROS-mediated cardiotoxicity will be explored and discussed, with emphasis on cardiomyocyte apoptosis leading to cardiomyopathy. The review will conclude with perspectives on model development needed to facilitate further progress and understanding on chemotherapy-induced cardiotoxicity.

PLCδ1 protein rescues ischemia-reperfused heart by the regulation of calcium homeostasis

Myocardial Ca(2+) overload induced by ischemia/reperfusion (I/R) is a major element of myocardial dysfunction in heart failure. Phospholipase C (PLC) plays important roles in the regulation of the phosphoinositol pathway and Ca(2+) homeostasis in various types of cells. Here, we investigated the protective role of PLCδ1 against myocardial I/R injury through the regulation of Ca(2+) homeostasis. To investigate its role, PLCδ1 was fused to Hph1, a cell-permeable protein transduction domain (PTD), and treated into rat neonatal cardiomyocytes and rat hearts under respective hypoxia-reoxygenation (H/R) and ischemia-reperfusion conditions. Treatment with Hph1-PLCδ1 significantly inhibited intracellular Ca(2+) overload, reactive oxygen species generation, mitochondrial permeability transition pore opening, and mitochondrial membrane potential elevation in H/R neonatal cardiomyocytes, resulting in the inhibition of apoptosis. Intravenous injections of Hph1-PLCδ1 in rats with I/R-injured myocardium caused significant reductions in infarct size and apoptosis and also improved systolic and diastolic cardiac functioning. Furthermore, a small ions profile obtained using time-of-flight secondary ion mass spectrometry showed that treatment with Hph1-PLCδ1 leads to significant recovery of calcium-related ions toward normal levels in I/R-injured myocardium. These results suggest that Hph1-PLCδ1 may manifest as a promising cardioprotective drug due to its inhibition of the mitochondrial apoptotic pathway in cells suffering from I/R injury.

Pharmacogenomics as a risk mitigation strategy for chemotherapeutic cardiotoxicity

Damage to the heart can result from both traditional chemotherapeutic agents, such as doxorubicin, and newer 'targeted' therapies, such as trastuzumab. This chemotherapeutic cardiotoxicity is potentially life-threatening and necessitates limiting or discontinuing an otherwise-effective cancer treatment. Clinical strategies focus on surveillance rather than prevention, although there are no specific therapies for this highly morbid adverse effect. Current models for prospectively predicting risk of chemotherapeutic cardiotoxicity are limited. Cardiotoxicity can occur idiosyncratically in patients without obvious demographic risk factors, suggesting a genetically determined susceptibility, and candidate-gene studies have identified a limited number of variants that increase risk. In this commentary we indicate a need for more powerful means to identify risk prospectively, and suggest that broad pharmacogenomic approaches may be fruitful.

Global changes in the rat heart proteome induced by prolonged morphine treatment and withdrawal

Morphine belongs among the most commonly used opioids in medical practice due to its strong analgesic effects. However, sustained administration of morphine leads to the development of tolerance and dependence and may cause long-lasting alterations in nervous tissue. Although proteomic approaches enabled to reveal changes in multiple gene expression in the brain as a consequence of morphine treatment, there is lack of information about the effect of this drug on heart tissue. Here we studied the effect of 10-day morphine exposure and subsequent drug withdrawal (3 or 6 days) on the rat heart proteome. Using the iTRAQ technique, we identified 541 proteins in the cytosol, 595 proteins in the plasma membrane-enriched fraction and 538 proteins in the mitochondria-enriched fraction derived from the left ventricles. Altogether, the expression levels of 237 proteins were altered by morphine treatment or withdrawal. The majority of changes (58 proteins) occurred in the cytosol after a 3-day abstinence period. Significant alterations were found in the expression of heat shock proteins (HSP27, α-B crystallin, HSP70, HSP10 and HSP60), whose levels were markedly up-regulated after morphine treatment or withdrawal. Besides that morphine exposure up-regulated MAPK p38 (isoform CRA_b) which is a well-known up-stream mediator of phosphorylation and activation of HSP27 and α-B crystallin. Whereas there were no alterations in the levels of proteins involved in oxidative stress, several changes were determined in the levels of pro- and anti-apoptotic proteins. These data provide a complex view on quantitative changes in the cardiac proteome induced by morphine treatment or withdrawal and demonstrate great sensitivity of this organ to morphine.

Alopecia in a viable phospholipase C delta 1 and phospholipase C delta 3 double mutant

BACKGROUND

Inositol 1,4,5trisphosphate (IP(3)) and diacylglycerol (DAG) are important intracellular signalling molecules in various tissues. They are generated by the phospholipase C family of enzymes, of which phospholipase C delta (PLCD) forms one class. Studies with functional inactivation of Plcd isozyme encoding genes in mice have revealed that loss of both Plcd1 and Plcd3 causes early embryonic death. Inactivation of Plcd1 alone causes loss of hair (alopecia), whereas inactivation of Plcd3 alone has no apparent phenotypic effect. To investigate a possible synergy of Plcd1 and Plcd3 in postnatal mice, novel mutations of these genes compatible with life after birth need to be found.

METHODOLOGY/PRINCIPAL FINDINGS

We characterise a novel mouse mutant with a spontaneously arisen mutation in Plcd3 (Plcd3(mNab)) that resulted from the insertion of an intracisternal A particle (IAP) into intron 2 of the Plcd3 gene. This mutation leads to the predominant expression of a truncated PLCD3 protein lacking the N-terminal PH domain. C3H mice that carry one or two mutant Plcd3(mNab) alleles are phenotypically normal. However, the presence of one Plcd3(mNab) allele exacerbates the alopecia caused by the loss of functional Plcd1 in Del(9)olt1Pas mutant mice with respect to the number of hair follicles affected and the body region involved. Mice double homozygous for both the Del(9)olt1Pas and the Plcd3(mNab) mutations survive for several weeks and exhibit total alopecia associated with fragile hair shafts showing altered expression of some structural genes and shortened phases of proliferation in hair follicle matrix cells.

CONCLUSIONS/SIGNIFICANCE

The Plcd3(mNab) mutation is a novel hypomorphic mutation of Plcd3. Our investigations suggest that Plcd1 and Plcd3 have synergistic effects on the murine hair follicle in specific regions of the body surface.

Tissue transglutaminase 2 promotes apoptosis of rat neonatal cardiomyocytes under oxidative stress

The role of tissue transglutaminase 2 (TG2) in cardiac myocyte apoptosis under oxidative stress induced by ischemic injury remains unclear. Here, we investigated the effects of TG2 on apoptosis of cardiomyocytes under oxidative stress. Ectopic expression of TG2 increased caspase-3 activity and calcium overload in cardiomyocytes. Expression levels of TG2 were significantly increased in H(2)O(2)-treated cardiomyocytes. Caspase-3 activity assay demonstrated its considerable correlation with TG2 expression, which supported that caspase-3 inhibitor inhibited the apoptosis induced by the ectopic overexpression of TG2. In addition, the other apoptotic signals, such as caspase-8, cytochrome c, and Bax, were increased dependent with TG2 expression in H(2)O(2)-treated cardiomyocytes. These results indicated that apoptotic signals had a positive correlation with TG2 expression. The decreased expression of phospholipase C (PLC)-δ1 and phospho-PKC in H(2)O(2)-treated cardiomyocytes were rescued by TG2 silencing. Together, our data strongly suggest that oxidative stress up-regulates TG2 expression in cardiomyocytes, leading to apoptosis.

TNF/TNFR1 signaling mediates doxorubicin-induced diaphragm weakness

Doxorubicin, a common chemotherapeutic agent, causes respiratory muscle weakness in both patients and rodents. Tumor necrosis factor-α (TNF), a proinflammatory cytokine that depresses diaphragm force, is elevated following doxorubicin chemotherapy. TNF-induced diaphragm weakness is mediated through TNF type 1 receptor (TNFR1). These findings lead us to hypothesize that TNF/TNFR1 signaling mediates doxorubicin-induced diaphragm muscle weakness. We tested this hypothesis by treating C57BL/6 mice with a clinical dose of doxorubicin (20 mg/kg) via intravenous injection. Three days later, we measured contractile properties of muscle fiber bundles isolated from the diaphragm. We tested the involvement of TNF/TNFR1 signaling using pharmaceutical and genetic interventions. Etanercept, a soluble TNF receptor, and TNFR1 deficiency protected against the depression in diaphragm-specific force caused by doxorubicin. Doxorubicin stimulated an increase in TNFR1 mRNA and protein (P < 0.05) in the diaphragm, along with colocalization of TNFR1 to the plasma membrane. These results suggest that doxorubicin increases diaphragm sensitivity to TNF by upregulating TNFR1, thereby causing respiratory muscle weakness.

The small GTPase Ral couples the angiotensin II type 1 receptor to the activation of phospholipase C-delta 1

The angiotensin II type 1 receptor (AT(1)R) plays an important role in cardiovascular function and as such represents a primary target for therapeutic intervention. The AT(1)R has traditionally been considered to be coupled to the activation of phospholipase C (PLC) beta via its association with G alpha(q/11), leading to increases in intracellular inositol phosphate (IP) and release of calcium from intracellular stores. In the present study, we investigated whether the small GTPase RalA contributed to the regulation of AT(1)R endocytosis and signaling. We find that neither RalA nor RalB is required for the endocytosis of the AT(1)R, but that RalA expression is required for AT(1)R-stimulated IP formation but not 5-HT(2A) receptor-mediated IP formation. AT(1)R-activated IP formation is lost in the absence of Ral guanine nucleotide dissociation stimulator (RalGDS), and requires the beta-arrestin-dependent plasma membrane translocation of RalGDS. G alpha(q/11) small interfering RNA (siRNA) treatment also significantly attenuates both AT(1)R- and 5-HT(2A) receptor-stimulated IP formation after 30 min of agonist stimulation. PLC-delta1 has been reported to be activated by RalA, and we show that AT(1)R-stimulated IP formation is attenuated after PLC-delta 1 siRNA treatment. Taken together, our results provide evidence for a G protein-coupled recepto-activated and RalGDS/Ral-mediated mechanism for PLC-delta 1 stimulation.

Toxicogenomics: transcription profiling for toxicology assessment

Toxicogenomics, the application of transcription profiling to toxicology, has been widely used for elucidating the molecular and cellular actions of chemicals and other environmental stressors on biological systems, predicting toxicity before any functional damages, and classification of known or new toxicants based on signatures of gene expression. The success of a toxicogenomics study depends upon close collaboration among experts in different fields, including a toxicologist or biologist, a bioinformatician, statistician, physician and, sometimes, mathematician. This review is focused on toxicogenomics studies, including transcription profiling technology, experimental design, significant gene extraction, toxicological results interpretation, potential pathway identification, database input and the applications of toxicogenomics in various fields of toxicological study.

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

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

Phenylbutyrate, a histone deacetylase inhibitor, protects against Adriamycin-induced cardiac injury

Cardiac injury is a major complication for oxidative-stress-generating anticancer agents exemplified by Adriamycin (ADR). Recently, several histone deacetylase inhibitors (HDACIs) including phenylbutyrate (PBA) have shown promise in the treatment of cancer with little known toxicity to normal tissues. PBA has been shown to protect against oxidative stress in normal tissues. Here, we examined whether PBA might protect heart against ADR toxicity in a mouse model. The mice were i.p. injected with ADR (20 mg/kg). PBA (400 mg/kg/day) was i.p. injected 1 day before and daily after the ADR injection for 2 days. We found that PBA significantly decreased the ADR-associated elevation of serum lactate dehydrogenase and creatine kinase activities and diminished ADR-induced ultrastructural damages of cardiac tissue by more than 70%. Importantly, PBA completely rescued ADR-caused reduction of cardiac functions exemplified by ejection fraction and fraction shortening, and increased cardiac manganese superoxide dismutase (MnSOD) protein and activity. Our results reveal a previously unrecognized role of HDACIs in protecting against ADR-induced cardiac injury and suggest that PBA may exert its cardioprotective effect, in part, by the increase of MnSOD. Thus, combining HDACIs with ADR could add a new mechanism to fight cancer while simultaneously decrease ADR-induced cardiotoxicity.