Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Trastuzumab, a monoclonal antibody that is selective for cells that overexpress the erbB2 receptor protein tyrosine kinase, is a promising targeted therapy for the treatment of breast cancer. Surprisingly, toxic cardiovascular side effects were discovered in late-phase clinical trials, and these effects were most prominent when trastuzumab was combined with anthracycline chemotherapy. We review recent data focusing on how erbB2 monoclonal antibodies could exert a cardiotoxic effect through unique cardiomyocyte cell surface and intracellular structural features, and how an individual's cardiac susceptibility to erbB2 monoclonal antibodies may be dictated by the ability of erbB2 monoclonal antibodies to bind cardiomyocytes. In addition, we discuss ways that anthracyclines may also affect erbB2/erbB4/neuregulin receptor signaling, explaining the apparent synergistic effect. Further investigation of the role of normal and aberrant erbB2 signaling in the development of cardiac dysfunction could lead to an improved understanding of the pathophysiology of cardiac dysfunction and may lead to novel therapies for the treatment of heart failure, regardless of etiology. Understanding the nature and specificity of trastuzumab's cardiotoxic effects is important in better defining clinical criteria for inclusion and exclusion of patients who can safely receive trastuzumab for the treatment of breast cancer, or possibly other malignancies.
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PMID:Trastuzumab cardiotoxicity: Speculations regarding pathophysiology and targets for further study. 1213 94

Experimental work during the past 15 years has demonstrated that endothelial cells in the heart play an obligatory role in regulating and maintaining cardiac function, in particular, at the endocardium and in the myocardial capillaries where endothelial cells directly interact with adjacent cardiomyocytes. The emerging field of targeted gene manipulation has led to the contention that cardiac endothelial-cardiomyocytal interaction is a prerequisite for normal cardiac development and growth. Some of the molecular mechanisms and cellular signals governing this interaction, such as neuregulin, vascular endothelial growth factor, and angiopoietin, continue to maintain phenotype and survival of cardiomyocytes in the adult heart. Cardiac endothelial cells, like vascular endothelial cells, also express and release a variety of auto- and paracrine agents, such as nitric oxide, endothelin, prostaglandin I(2), and angiotensin II, which directly influence cardiac metabolism, growth, contractile performance, and rhythmicity of the adult heart. The synthesis, secretion, and, most importantly, the activities of these endothelium-derived substances in the heart are closely linked, interrelated, and interactive. It may therefore be simplistic to try and define their properties independently from one another. Moreover, in relation specifically to the endocardial endothelium, an active transendothelial physicochemical gradient for various ions, or blood-heart barrier, has been demonstrated. Linkage of this blood-heart barrier to the various other endothelium-mediated signaling pathways or to the putative vascular endothelium-derived hyperpolarizing factors remains to be determined. At the early stages of cardiac failure, all major cardiovascular risk factors may cause cardiac endothelial activation as an adaptive response often followed by cardiac endothelial dysfunction. Because of the interdependency of all endothelial signaling pathways, activation or disturbance of any will necessarily affect the others leading to a disturbance of their normal balance, leading to further progression of cardiac failure.
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PMID:Cardiac endothelial-myocardial signaling: its role in cardiac growth, contractile performance, and rhythmicity. 1250 27

The proto-oncogene ErbB2 (also known as c-neu or HER2 in humans) encodes a receptor tyrosine kinase that is frequently overexpressed in human tumors. It is the target of a novel and effective antibody-based therapy for malignant mammary tumors (trastuzumab/Herceptin). Biochemical and genetic experiments have shown that ErbB2 acts as a coreceptor for other members of the ErbB family of receptor tyrosine kinases. In particular, signals are transduced by ErbB2/ErbB4, ErbB2/ErbB3, and ErbB2/EGF receptor heteromers. ErbB2/4 and ErbB2/ErbB3 heteromers transmit neuregulin-1 signals in the developing and adult heart, and in the peripheral nervous system, respectively. Of particular medical relevance are recent findings that relied on tissue-specific mutation of ErbB2 in cardiomyocytes, which revealed an essential function of ErbB2 in normal heart physiology and demonstrated that loss of cardiac ErbB2 can cause dilated cardiomyopathy in adult mice. Thus, ErbB2 is important not only in development, but also for the correct functioning of the differentiated myocardium. The conditional ErbB2 mutant mice provide a model for the principal side effects--cardiomyopathy and heart failure--that can be observed in patients undergoing chemotherapy with Trastuzumab.
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PMID:ErbB2 pathways in heart and neural diseases. 1258 44

The neuregulin-1 family of growth factors regulates nicotinic acetylcholine receptor synthesis in skeletal muscle, but its role in cardiac myogenesis remains unclear. Here, we investigate the involvement of neuregulins in the development of cardiac cholinergic responsiveness. Treatment of chick cardiac myocytes with neuregulin-1 inhibited mRNA expression of the M4 muscarinic receptor, but not the M2 receptor. In addition, mRNA levels of GIRK1 were reduced in myocytes by treatment with neuregulin-1. Activation of cholinergic receptors in cultured chick atrial myocytes by carbachol produced an outward potassium current (I(K(ACh))), which was attenuated by 24-48-h pre-treatment with neuregulin-1. These data suggest that neuregulins can regulate cardiac parasympathetic tone and may be involved in the pathogenesis of cardiac arrhythmias and heart failure.
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PMID:Neuregulin-1 suppresses muscarinic receptor expression and acetylcholine-activated muscarinic K+ channels in cardiac myocytes. 1289 Apr 74

Membrane-bound and secreted neuregulin isoforms induce growth, survival and differentiation by activating erbB tyrosine kinase receptors. In cultured cardiomyocytes, erbB2 and erbB4 receptors regulate apoptosis by controlling bcl-x splicing, and conditional elimination of erbB2 induces dilative cardiomyopathy in vivo. Therefore, we analyzed expression and activation of erbB receptors in left ventricular myocardium from 32 heart failure patients, from 10 organ donors, and from 15 heart failure patients prior to and following unloading by ventricular assist devices. ErbB receptors, expressed in cardiomyocytes and noncardiomyocytes, are downregulated in failing myocardium as mRNA (which is renormalized by hemodynamic unloading) and as protein (erbB2: -25%; erbB4: -70%), their phosphorylation is reduced and bcl-x splicing is shifted towards 6.7-fold augmentation of proapoptotic Bcl-xS, compatible with attenuated erbB signaling. However, secreted and membrane-anchored neuregulin-1 isoforms, preferentially expressed in microvascular endothelium, are induced and not lowered with heart failure, while expression of erbB-inhibitory neuregulin isoforms or of autoinhibitory soluble erbB isoforms could not be demonstrated as potential causes of erbB receptor inhibition. We conclude that erbB receptor inactivation by unknown mechanisms results in altered splicing of bcl-x towards enhanced formation of proapoptotic Bcl-xS, thereby contributing to enhanced apoptotic susceptibility of failing human myocardium.
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PMID:Neuregulin receptors erbB2 and erbB4 in failing human myocardium -- depressed expression and attenuated activation. 1568 97

During chemotherapy with anthracyclines, attenuated neuregulin signaling by the erbB2 receptor inactivating antibody Trastuzumab enhances the heart failure risk. We compared the effects of attenuated neuregulin/erbB signaling and of daunorubicin on splicing of the Bcl-x gene and on mitochondrial activation of apoptosis in cardiomyocytes. Attenuating erbB signals in cultured neonatal rat cardiomyocytes by the erbB2 antagonist tyrphostin AG825, by the erbB1/4 antagonist AG1478 or by antisense-induced lowering of erbB2 receptors resulted in an augmented Bcl-xS/Bcl-xL ratio, mitochondrial release of cytochrome c, activation of caspase 9 and caspase 3, and nucleosome-sized DNA fragmentation. A similar DNA fragmentation and caspase 3 activation was induced by TNF-alpha, but without Bcl-xS/Bcl-xL increase, cytochrome c release or caspase 9 activation. A BH4-domain containing HIV TAT fusion protein added to cardiomyocytes under attenuated erbB signaling lowered the enhanced Bcl-xS/Bcl-xL ratio, the cytochrome c release, the caspase 3 activation and the DNA fragmentation, while apoptosis was not modified by the fusion protein in TNF-alpha treated cardiomyocytes. Enhancement of Bcl-xS/Bcl-xL by reducing Bcl-xL via siRNA transfection mimicked the mitochondrial apoptotic activation due to erbB signal attenuation. Daunorubicin also caused Bcl-xS/Bcl-xL enhancement and mitochondrial apoptotic activation in cultured cardiomyocytes; this was attenuated by BH4-fusion protein or by neuregulin-1 and augmented by siRNA-mediated Bcl-xL lowering. We conclude that activation of mitochondrial apoptosis due to altered Bcl-x splicing contributes as a common mechanism of anthracyclines and erbB signal attenuation to the enhanced heart failure risk under this combination.
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PMID:Apoptosis-modulating interaction of the neuregulin/erbB pathway with anthracyclines in regulating Bcl-xS and Bcl-xL in cardiomyocytes. 1573 8

The neuregulin/ErbB system is a growth factor/receptor cascade that has been proven to be essential in the development of the heart and the sympathetic nervous system. However, the basis of the specificity of ligand-receptor recognition remains to be elucidated. In this study, the structures of NRG-1beta/ErbB3 and NRG-1beta/ErbB4 complexes were modeled based on the available structures of the homologous proteins. The binding free energies of NRG-1beta to ErbB3 and ErbB4 were calculated using the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) computational method. In addition, computational alanine-scanning mutagenesis was performed in the binding site of NRG-1beta and the difference in the binding free energies between NRG-1beta mutants and the receptors was calculated. The results specify the contribution of each residue at the interaction interfaces to the binding affinity of NRG-1beta with ErbB3 and ErbB4, identifying several important interaction residue pairs that are in agreement with previously acquired experimental data. This indicates that the presented structural models of NRG-1beta/ErbB3 and NRG-1beta/ErbB4 complexes are reliable and could be used to guide future studies, such as performing desirable mutations on NRG-1beta to increase the binding affinity and selectivity to the receptor and discovering new therapeutic agents for the treatment of heart failure.
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PMID:Computational analysis of molecular basis of 1:1 interactions of NRG-1beta wild-type and variants with ErbB3 and ErbB4. 1582 27

Treatment of metastatic breast cancer with doxorubicin (Doxo) in combination with trastuzumab, an antibody targeting the ErbB2 receptor, results in an increased incidence of heart failure. Doxo therapy induces reactive oxygen species (ROS) and alterations of calcium homeostasis. Therefore, we hypothesized that neuregulin-1 beta (NRG), a ligand of the cardiac ErbB receptors, reduces Doxo-induced alterations of EC coupling by triggering antioxidant mechanisms. Adult rat ventricular cardiomyocytes (ARVM) were isolated and treated for 18-48 h. SERCA protein was analyzed by Western blot, EC coupling parameters by fura-2 and video edge detection, gene expression by RT-PCR, and ROS by DCF-fluorescence microscopy. At clinically relevant doses Doxo reduced cardiomyocytes contractility, SERCA protein and SR calcium content. NRG, similarly as the antioxidant N-acetylcystein (NAC), did not affect EC coupling alone, but protected against Doxo-induced damage. NRG and Doxo showed an opposite modulation of glutathione reductase gene expression. NRG, similarly as NAC, reduced peroxide- or Doxo-induced oxidative stress. Specific inhibitors showed, that the antioxidant action of NRG depended on signaling via the ErbB2 receptor and on the Akt- and not on the MAPK-pathway. Therefore, NRG attenuates Doxo-induced alterations of EC coupling and reduces oxidative stress in ARVM. Inhibition of the ErbB2/NRG signaling pathway by trastuzumab in patients concomitantly treated with Doxo might prevent beneficial effects of NRG in the myocardium.
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PMID:Neuregulin-1 beta attenuates doxorubicin-induced alterations of excitation-contraction coupling and reduces oxidative stress in adult rat cardiomyocytes. 1700 95

Grb2-associated binder (Gab) family of scaffolding adaptor proteins coordinate signaling cascades downstream of growth factor and cytokine receptors. In the heart, among EGF family members, neuregulin-1beta (NRG-1beta, a paracrine factor produced from endothelium) induced remarkable tyrosine phosphorylation of Gab1 and Gab2 via erythroblastic leukemia viral oncogene (ErbB) receptors. We examined the role of Gab family proteins in NRG-1beta/ErbB-mediated signal in the heart by creating cardiomyocyte-specific Gab1/Gab2 double knockout mice (DKO mice). Although DKO mice were viable, they exhibited marked ventricular dilatation and reduced contractility with aging. DKO mice showed high mortality after birth because of heart failure. In addition, we noticed remarkable endocardial fibroelastosis and increase of abnormally dilated vessels in the ventricles of DKO mice. NRG-1beta induced activation of both ERK and AKT in the hearts of control mice but not in those of DKO mice. Using DNA microarray analysis, we found that stimulation with NRG-1beta upregulated expression of an endothelium-stabilizing factor, angiopoietin 1, in the hearts of control mice but not in those of DKO mice, which accounted for the pathological abnormalities in the DKO hearts. Taken together, our observations indicated that in the NRG-1beta/ErbB signaling, Gab1 and Gab2 of the myocardium are essential for both maintenance of myocardial function and stabilization of cardiac capillary and endocardial endothelium in the postnatal heart.
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PMID:Gab family proteins are essential for postnatal maintenance of cardiac function via neuregulin-1/ErbB signaling. 1757 Nov 62

The molecular and cellular mechanisms that cause cumulative dose-dependent anthracycline-cardiotoxicity remain controversial and incompletely understood. Studies examining the effects of anthracyclines in cardiac myocytes inA vitro have demonstrated several forms of cellular injury. Cell death in response to anthracyclines can be observed by one of several mechanisms including apoptosis and necrosis. Cell death by apoptosis can be inhibited by dexrazoxane, the iron chelator that is known to prevent clinical development of heart failure at high cumulative anthracycline exposure. Together with clinical evidence for myocyte death after anthracycline exposure, in the form of elevations in serum troponin, make myocyte cell death a probable mechanism for anthracycline-induced cardiac injury. Other mechanisms of myocyte injury include the development of cellular \'sarcopenia\' characterized by disruption of normal sarcomere structure. Anthracyclines suppress expression of several cardiac transcription factors, and this may play a role in the development of myocyte death as well as sarcopenia. Degradation of the giant myofilament protein titin may represent an important proximal step that leads to accelerated myofilament degradation. Titin is an entropic spring element in the sarcomere that regulates length-dependent calcium sensitivity. Thus titin degradation may lead to impaired diastolic as well as systolic dysfunction, as well as potentiate the effect of suppression of transcription of sarcomere proteins. An interesting interaction has been noted clinically between anthracyclines and newer cancer therapies that target the erbB2 receptor tyrosine kinase. Studies of erbB2 function in viro suggest that signaling through erbB2 by the growth factor neuregulin may regulate cardiac myocyte sarcomere turnover, as well as myocyte-myocyte/myocyte-matrix force coupling. A combination of further in vitro studies, with more careful monitoring of cardiac function after exposure to these cancer therapies, may help to understand to what extent these mechanisms are at work during clinical exposure of the heart to these important pharmaceuticals.
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PMID:Molecular and cellular mechanisms of anthracycline cardiotoxicity. 1765 15


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