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Receptor Tyrosine Kinase (receptor tyrosine + kinase)
Kinds of Receptor Tyrosine Kinase Terms modified by Receptor Tyrosine Kinase Selected AbstractsSynthesis and anti-Tyrosine Kinase Activity of 3-(Substituted-benzylidene)-1,3-dihydro-indolin Derivatives: Investigation of Their Role Against p60c-Src Receptor Tyrosine Kinase with the Application of Receptor Docking Studies.CHEMINFORM, Issue 46 2005Sureyya Olgen Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of C-Nucleosidic ATP Mimics as Potential FGFR3 InhibitorsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2006Patricia Busca Abstract Receptor tyrosine kinases (RTKs) play an important role in signal transduction pathways, and in particular, FGFR3 is one of the four RTKs related to the fibroblast growth factor family. This paper describes the synthesis of C-nucleosidic ATP mimics, as potential FGFR3 inhibitors, by nucleophilic epoxide ring-opening followed by in situ O -heterocyclization of 1,2:5,6-dianhydro-3,4-di- O -benzyl- D -mannitol or L -iditol. Cesium carbonate [Cs2CO3] was found to be the best catalyst for the reaction of purine derivatives with these bis-epoxides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Furo[2,3- d]pyrimidines and Oxazolo[5,4- d]pyrimidines as Inhibitors of Receptor Tyrosine Kinases (RTK)HELVETICA CHIMICA ACTA, Issue 4 2004Andreas Martin-Kohler Receptor tyrosine kinases such as VEGFR2 (vascular endothelial growth factor receptor 2, KDR) or EGFR (epidermal growth factor receptor) play crucial roles in a variety of diseases, such as cancer. Recently, some pyrrolopyrimidines were shown to be potent EGFR inhibitors. Therefore, new types of oxazolo[5,4- d]pyrimidines and furo[2,3- d]pyrimidines were synthesized (Schemes,1 and 2). Appropriately substituted derivatives of these classes of compounds inhibited VEGFR2 and EGFR with IC50 values in the low nanomolar range (see Table). Generally, the furopyrimidines were somewhat more active than the oxazolopyrimidines. The best inhibitors, 20m, 20p, and 20r, had an IC50 of 3,nM towards EGFR and showed a good selectivity, being distinctly less active towards VEGFR2. [source] THERAPEUTIC HOTLINE: A rare vandetanib-induced photo-allergic drug eruptionDERMATOLOGIC THERAPY, Issue 5 2010Paolo Fava ABSTRACT Vandetanib is an inhibitor of the vascular endothelial growth factor receptor 2 tyrosine kinase and the epidermal growth factor receptor tyrosine kinase, recently used in the treatment of different tumors. We describe a case of a photo-allergic reaction to vandetanib in an 80-year-old Caucasian woman affected by metastatic non-small cell lung cancer. Phototoxic reactions to vandetanib have been rarely reported in the literature. Dermatologists should be aware of this cutaneous side effect of vandetanib treatment and affected patients should be counseled to use adequate sun protection. [source] Opposing effects on TSC-22 expression by BMP and receptor tyrosine kinase signals in the developing feather tractDEVELOPMENTAL DYNAMICS, Issue 1 2002Cord E. Dohrmann Abstract TSC-22 (transforming growth factor-,,stimulated clone 22) belongs to a family of leucine zipper transcription factors that includes sequences from invertebrates and vertebrates. The single Drosophila family member, encoded by the bunched gene, serves to integrate opposing bone morphogenic protein (BMP) and epidermal growth factor (EGF) signals during oogenesis. Similarly, mammalian TSC-22 expression is regulated by several families of secreted signaling molecules in cultured cells. Here, we show that chick TSC-22 is dynamically expressed in the condensing feather bud, as well as in many tissues of the chick embryo. BMP-2/4, previously shown to inhibit bud development, repress TSC-22 expression during feather bud formation in vivo. Noggin, a BMP antagonist, promotes TSC-22 expression. EGF, TGF-,, and fibroblast growth factor all promote both feather bud development and TSC-22 expression; each can promote ectopic feather buds that are regularly spaced between existing feather buds. Thus, TSC-22 is a candidate to integrate small imbalances in receptor tyrosine kinase and BMP signaling during feather tract development to generate stable and reproducible morphogenetic responses. © 2001 Wiley-Liss, Inc. [source] Impaired behavioural flexibility and memory in mice lacking GDNF family receptor ,2EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2004Vootele Vőikar Abstract The glial cell line-derived neurotrophic factor (GDNF) family receptor GFR,2 is the binding receptor for neurturin (NRTN). The main biological responses of GFR,2 are mediated via the Ret receptor tyrosine kinase, although it may also signal independently of Ret via the neural cell adhesion molecule NCAM. GFR,2 is expressed in many neurons of both the central and peripheral nervous system. Mice lacking GFR,2 receptors do not exhibit any gross defects in the central nervous system structure. However, they display profound deficits in the parasympathetic and enteric nervous system, accompanied by significant reduction in body weight after weaning. Here we present the results of behavioural analysis of the GFR,2-knockout mice. The knockout mice did not differ from wild-type mice in basic tests of motor and exploratory activity. However, differences were established in several memory tasks. The knockout mice were not impaired in the acquisition of spatial escape strategy. However, the deficit in flexibility in establishing a new strategy was revealed during reversal learning with the platform in the opposite quadrant of the pool. Furthermore, the knockout mice displayed significant impairment in contextual fear conditioning and conditioned taste aversion tests of memory. The results suggest that GFR,2 signalling plays a role in the development or maintenance of cognitive abilities that help in solving complex learning tasks. [source] Brain-derived neurotrophic factor induces long-lasting Ca2+ -activated K+ currents in rat visual cortex neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2002Yoshito Mizoguchi Abstract Brain-derived neurotrophic factor (BDNF) increases postsynaptic intracellular Ca2+ and modulates synaptic transmission in various types of neurons. Ca2+ -activated K+ currents, opened mainly by intracellular Ca2+ elevation, contribute to hyperpolarization following action potentials and modulate synaptic transmission. We asked whether BDNF induces Ca2+ -activated K+ currents by postsynaptic elevation of intracellular Ca2+ in acutely dissociated visual cortex neurons of rats. Currents were analysed using the nystatin-perforated patch clamp technique and imaging of intracellular Ca2+ mobilization with fura-2. At a holding potential of ,50 mV, BDNF application (20 ng/mL) for 1,2 min induced an outward current (IBDNF-OUT; 80.0 ± 29.0 pA) lasting for more than 90 min without attenuation in every neuron tested. K252a (200 nm), an inhibitor of Trk receptor tyrosine kinase, and U73122 (3 ,m), a specific phospholipase C (PLC)-, inhibitor, suppressed IBDNF-OUT completely. IBDNF-OUT was both charybdotoxin- (600 nm) and apamin- (300 nm) sensitive, suggesting that this current was carried by Ca2+ -activated K+ channels. BAPTA-AM (150 ,m) gradually suppressed IBDNF-OUT. Fura-2 imaging revealed that a brief application of BDNF elicited a long-lasting elevation of intracellular Ca2+. These results show that BDNF induces long-lasting Ca2+ -activated K+ currents by sustained intracellular Ca2+ elevation in rat visual cortex neurons. While BDNF, likely acting through the Trk B receptor, was necessary for the induction of long-lasting Ca2+ -activated K+ currents via intracellular Ca2+ elevation, BDNF was not necessary for the maintenance of this current. [source] Host factor Ebp1: Selective inhibitor of influenza virus transcriptaseGENES TO CELLS, Issue 2 2007Ayae Honda Influenza virus RNA polymerase is composed of three virus-coded proteins, and is involved in both transcription and replication of the negative-strand genome RNA. Subunit PB1 plays key roles in both the RNA polymerase assembly and the catalytic function of RNA polymerization. Using yeast two-hybrid screening, a HeLa cell protein with the molecular mass of 45 kDa was identified. After cloning and sequencing, this protein was identified to be Ebp1, ErbB3-binding protein. Epb1 specifically interacts with PB1 both in vitro and in vivo, and Epb1 contact site on PB1 was mapped at its binding site of transcription primers. Ebp1 was found to interfere with in vitro RNA synthesis by influenza virus RNA polymerase (3P complex), but no inhibition was observed for capped RNA endonuclease and RNA-cap binding, the intrinsic activities of RNA polymerase. Since inhibition was not observed against other nucleic acid polymerases tested, we propose that Ebp1 is a selective inhibitor of influenza viral RNA polymerase. Accordingly over-expression of Ebp1 interfered with virus production. The PB1-contact site on Ebp1 overlaps with the interaction site with ErbB3 (epidermal receptor tyrosine kinase), androgen receptor (AR) and retinoblastoma gene product (Rb), which are involved in controlling cell proliferation and differentiation. [source] Expression and mutational analysis of MET in human solid cancersGENES, CHROMOSOMES AND CANCER, Issue 12 2008Patrick C. Ma MET receptor tyrosine kinase and its ligand hepatocyte growth factor (HGF) regulate a variety of cellular functions, many of which can be dysregulated in human cancers. Activated MET signaling can lead to cell motility and scattering, angiogenesis, proliferation, branching morphogenesis, invasion, and eventual metastasis. We performed systematic analysis of the expression of the MET receptor and its ligand HGF in tumor tissue microarrays (TMA) from human solid cancers. Standard immunohistochemistry (IHC) and a computerized automated scoring system were used. DNA sequencing for MET mutations in both nonkinase and kinase domains was also performed. MET was differentially overexpressed in human solid cancers. The ligand HGF was widely expressed in both tumors, primarily intratumoral, and nonmalignant tissues. The MET/HGF likely is functional and may be activated in autocrine fashion in vivo. MET and stem cell factor (SCF) were found to be positively stained in the bronchioalevolar junctions of lung tumors. A number of novel mutations of MET were identified, particularly in the extracellular semaphorin domain and the juxtamembrane domain. MET-HGF pathway can be assayed in TMAs and is often overexpressed in a wide variety of human solid cancers. MET can be activated through overexpression, mutation, or autocrine signaling in malignant cells. Mutations in the nonkinase regions of MET might play an important role in tumorigenesis and tumor progression. MET would be an important therapeutic antitumor target to be inhibited, and in lung cancer, MET may represent a cancer early progenitor cell marker. © 2008 Wiley-Liss, Inc. [source] Mechanisms of resistance to EGFR inhibitors in head and neck cancer,HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 8 2009Jonathan B. Cooper BS Abstract Epidermal growth factor receptor (EGFR), a receptor tyrosine kinase that activates multiple signaling pathways, including phosphatidylinositol-3-kinase/v-AKT murine thymoma viral oncogene homolog protein (Akt), has long been a target of novel therapies. Despite universal EGFR expression in head and neck squamous cell carcinoma (HNSCC), the majority of patients do not respond to EGFR inhibitors. This review focuses on mechanisms of resistance to these agents in HNSCC, and how these may be unique when compared with other malignancies such as non-small cell lung and colorectal cancers. Published studies and abstracts reveal that there are likely several mechanisms underlying resistance, suggesting that different strategies will be required to improve efficacy of EGFR inhibitors in HNSCC. © 2009 Wiley Periodicals, Inc. Head Neck, 2009 [source] Molecular characterization of the vascular features of focal nodular hyperplasia and hepatocellular adenoma: A role for angiopoietin-1,HEPATOLOGY, Issue 2 2010Annette S. H. Gouw Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are two hepatic nodular lesions of different etiologies. FNH, a polyclonal lesion, is assumed to be a regenerative reaction following a vascular injury, whereas HCA is a monoclonal, benign neoplastic lesion. In addition to features that are predominantly found in either FNH or HCA (e.g., dystrophic vessels in FNH and single arteries in HCA), FNH and HCA share morphological vascular abnormalities such as dilated sinusoids. We hypothesized that these anomalous vascular features are associated with altered expression of growth factors involved in vascular remodeling. This was based on reports of morphologically abnormal hepatic vasculature and nodular lesions in transgenic models of hepatocytic overexpression of angiopoietin-1 (Ang-1), a member of the angiopoietin family, which is crucially involved in vascular morphogenesis and homeostasis. We investigated gene and protein expression of members of the angiopoietin system and vascular endothelial growth factor A (VEGF-A) and its receptors in 9 FNH samples, 13 HCA samples, and 9 histologically normal livers. In comparison with normal samples, a significant increase in Ang-1 was found in FNH (P < 0.01) and HCA (P < 0.05), whereas no significant changes in Ang-2, receptor tyrosine kinase with immunoglobulin-like and EGF-like domains 2, VEGF-A, or vascular endothelial growth factor receptor 2 (VEGFR-2) were observed. Conclusion: Because of the different etiological contexts of a preceding vascular injury in FNH and a neoplastic growth in HCA, Ang-1 might exert different effects on the vasculature in these lesions. In FNH, it could predominantly stimulate recruitment of myofibroblasts and result in dystrophic vessels, whereas in HCA, it may drive vascular remodeling that produces enlarged vessels and arterial sprouting that generates single arteries. Hepatology 2010 [source] Role of vascular endothelial growth factor and angiopoietin systems in serum of Crohn's disease patientsINFLAMMATORY BOWEL DISEASES, Issue 1 2008Inés D. Pousa Abstract Background: The purposes of this study were to determine soluble angiogenic factors in Crohn's disease (CD) patients and to compare these factors according to the pathological behavior of the disease in order to establish a possible relationship with its evolution in patients with CD. Methods: Blood samples were collected from 70 patients with CD, grouped according to their phenotypic behavior, and from 30 healthy controls. Vascular endothelial growth factor (VEGF), placental growth factor (PlGF), angiopoietin 1 (Ang1), angiopoietin 2 (Ang2), and their cognate receptors [VEGFR1, VEGFR2, and angiopoietin receptor tyrosine kinase (Tie2)] were assayed by ELISA. Results: Circulating levels of VEGF, PlGF, VEGFR1, Ang2, and Tie2 were significantly higher in CD patients than in healthy controls (489 ± 271 versus 335 ± 118 pg/mL, P < 0.001; 31 ± 9 versus 23 ± 9 pg/mL, P < 0.001; 1.7 ± 0.4 versus 1.0 ± 0.3 ng/mL, P < 0.001; 4.8 ± 2.0 versus 3.9 ± 2.0 ng/mL, P < 0.05; and 36 ± 5 versus 22 ± 7 ng/mL, P < 0.001, respectively). Conversely, CD patients showed significantly lower serum levels of Ang1 than healthy controls (40 ± 12 versus 67 ± 22 ng/mL; P < 0.001). No differences between the groups were found in VEGFR2 serum level. The circulating levels of the angiogenic factors did not differ significantly when the CD patients were classified according to pathological phenotype. Conclusions: In comparison with healthy controls, CD patients were found to have an active angiogenic profile, as detected by significant alterations in levels of angiogenesis soluble markers. These patients did not differ in serum levels of angiogenic factors according to phenotypic disease behavior. (Inflamm Bowel Dis 2007) [source] Targeting the epidermal growth factor receptor by erlotinib (TarcevaÔ) for the treatment of esophageal cancerINTERNATIONAL JOURNAL OF CANCER, Issue 7 2006Andreas P. Sutter Abstract Esophageal cancer is the sixth most common cause of cancer-related death worldwide. Because of very poor 5-year survival new therapeutic approaches are mandatory. Erlotinib (TarcevaÔ), an inhibitor of epidermal growth factor receptor tyrosine kinase (EGFR-TK), potently suppresses the growth of various tumors but its effect on esophageal carcinoma, known to express EGFR, remains unexplored. We therefore studied the antineoplastic potency of erlotinib in human esophageal cancer cells. Erlotinib induced growth inhibition of the human esophageal squamous cell carcinoma (ESCC) cell lines Kyse-30, Kyse-70 and Kyse-140, and the esophageal adenocarcinoma cell line OE-33, as well as of primary cell cultures of human esophageal cancers. Combining erlotinib with the EGFR-receptor antibody cetuximab, the insulin-like growth factor receptor tyrosine kinase inhibitor tyrphostin AG1024, or the 3-hydroxy-3-methylglutaryl coenzyme. A reductase (HMG-CoAR) inhibitor fluvastatin resulted in additive or even synergistic antiproliferative effects. Erlotinib induced cell cycle arrest at the G1/S checkpoint. The erlotinib-mediated signaling involved the inactivation of EGFR-TK and ERK1/2, the upregulation of the cyclin-dependent kinase inhibitors p21Waf1/CIP1 and p27Kip1, and the downregulation of the cell cycle promoter cyclin D1. However, erlotinib did not induce immediate cytotoxicity or apoptosis in esophageal cancer cells. The inhibition of EGFR-TK by erlotinib appears to be a promising novel approach for innovative treatment strategies of esophageal cancer, as it powerfully induced growth inhibition and cell cycle arrest in human esophageal cancer cells and enhanced the antineoplastic effects of other targeted agents. © 2005 Wiley-Liss, Inc. [source] Molecular regulation of postsynaptic differentiation at the neuromuscular junctionIUBMB LIFE, Issue 11 2005Raghavan Madhavan Abstract The neuromuscular junction (NMJ) is a synapse that develops between a motor neuron and a muscle fiber. A defining feature of NMJ development in vertebrates is the re-distribution of muscle acetylcholine (ACh) receptors (AChRs) following innervation, which generates high-density AChR clusters at the postsynaptic membrane and disperses aneural AChR clusters formed in muscle before innervation. This process in vivo requires MuSK, a muscle-specific receptor tyrosine kinase that triggers AChR re-distribution when activated; rapsyn, a muscle protein that binds and clusters AChRs; agrin, a nerve-secreted heparan-sulfate proteoglycan that activates MuSK; and ACh, a neurotransmitter that stimulates muscle and also disperses aneural AChR clusters. Moreover, in cultured muscle cells, several additional muscle- and nerve-derived molecules induce, mediate or participate in AChR clustering and dispersal. In this review we discuss how regulation of AChR re-distribution by multiple factors ensures aggregation of AChRs exclusively at NMJs. IUBMB Life, 57: 719-730, 2005 [source] Deficiency of KIT-positive cells in the colon of patients with diabetes mellitusJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 6 2002MASANORI NAKAHARA Abstract Background Diabetes mellitus is a well-known cause of gastrointestinal dysmotility. The pathogenesis of diabetic gastroenteropathy is mainly considered to be a neuropathy, but the cause of dysmotility remains unknown. Interstitial cells of Cajal (ICC), which express c-kit receptor tyrosine kinase (KIT), are considered to be pacemaker cells for the gastrointestinal movement. Therefore, we investigated a possible involvement of ICC in the pathogenesis of diabetic gastroenteropathy in humans. Methods The KIT-positive cells in the proper muscle layer of the colon were detected by immunohistochemistry in patients with diabetes mellitus and normal control subjects. Mast cells, which are also known to express KIT, were detected by staining with Alcian blue. The numbers of KIT-positive cells and Alcian blue-positive cells in the proper muscle layer were counted under the microscope and the number of KIT-positive cells apart from Alcian blue-positive cells was calculated. Results In the normal control subjects, KIT-positive cells were located at the myenteric plexus region and in the circular muscle layer of the colon. Their distribution pattern was similar to that of ICC. The average number of KIT-positive cells, apart from mast cells (which reflects the number of ICC), in patients with diabetes mellitus was approximately 40% of that found in normal subjects. Conclusions Deficiency of ICC might be related to the pathogenesis of diabetic gastroenteropathy in humans. [source] The cell migration protein Grb7 associates with transcriptional regulator FHL2 in a Grb7 phosphorylation-dependent mannerJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2009Sharareh Siamakpour-Reihani Abstract Grb7 is an adaptor molecule that can mediate signal transduction from multiple cell surface receptors to various downstream signaling pathways. Grb7, along with Grb10 and Grb14, make up the Grb7 protein family. This protein family has been shown to be overexpressed in certain cancers and cancer cell lines. Grb7 and a receptor tyrosine kinase (RTK), erbB2, are overexpressed in 20,30% of breast cancers. Grb7 overexpression has been linked to enhanced cell migration and metastasis, though the participants in these pathways have not been determined. In this study, we report that Grb7 interacts with four and half lim domains isoform 2 (FHL2), a transcription regulator with an important role in oncogenesis, including breast cancer. Additionally, in yeast 2-hybrid (Y2H) assays, we show that the interaction is specific to the Grb7 RA and PH domains. We have also demonstrated that full-length (FL) Grb7 and FHL2 interact in mammalian cells and that Grb7 must be tyrosine phosphorylated for this interaction to occur. Immunofluorescent microscopy demonstrates possible co-localization of Grb7 and FHL2. A model with supporting NMR evidence of Grb7 autoinhibition is proposed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Identification of developmentally regulated expression of MuSK in astrocytes of the rodent retinaJOURNAL OF NEUROCHEMISTRY, Issue 2 2006Tatiana Cheusova Abstract One of the master regulators of postsynaptic neuromuscular synaptogenesis is the muscle-specific receptor tyrosine kinase (MuSK). In mammals prominent MuSK expression is believed to be restricted to skeletal muscle. Upon activation by nerve-derived agrin MuSK-dependent signalling participates in both the induction of genes encoding postsynaptic components and aggregation of nicotinic acetylcholine receptors (AChR) in the subsynaptic muscle membrane. Strikingly, expression of certain isoforms of nerve-derived agrin can also be detected in the CNS. In this study, we examined the expression of MuSK in the brain and eye of rodents. In the retina MuSK was expressed in astrocytes between postnatal days 7 and 14, i.e. at the time when the eyes open. We found that agrin was localized adjacent to MuSK-expressing astrocytes which in turn were detected close to the inner limiting membrane of the rodent retina. In summary, the presence of MuSK on retinal astrocytes suggests a novel role of MuSK signalling pathways in the CNS. [source] Discoidin domain receptor 1 mediates collagen-induced inflammatory activation of microglia in cultureJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2008Min-Chul Seo Abstract Discoidin domain receptor 1 (DDR1) is a nonintegrin collagen receptor tyrosine kinase with an extracellular domain homologous to discoidin 1 of a soil-living amoeba Dictyostelium discoideum. We have previously demonstrated that DDR1 mediates collagen-induced nitric oxide production in J774A.1 murine macrophages. Because collagen is one of the main components of extracellular matrix in the central nervous system, we hypothesized that collagen also induces inflammatory activation of brain microglia, and DDR1 may mediate collagen-induced microglial activation. Using BV-2 mouse microglial cells and mouse primary microglial cultures, we have demonstrated that (1) collagen induces inflammatory activation of microglia as evidenced by production of nitric oxide, expression of inducible nitric oxide synthase, COX-2, CD40, and matrix metalloproteinase,9; (2) DDR1 is expressed in microglia and is phosphorylated by collagen treatment; and (3) collagen-induced microglial activation is abrogated by DDR1 blockade but not by integrin neutralization. We have further shown that p38 MAPK, c-Jun N-terminal kinase, and nuclear factor,kappa B are involved in the collagen-DDR1-induced microglial activation. Our results suggest that collagen can induce inflammatory activation of brain microglia and that DDR1 mediates this effect of collagen in an integrin-independent manner. © 2007 Wiley-Liss, Inc. [source] Calcium channel upregulation in response to activation of neurotrophin and surrogate neurotrophin receptor tyrosine kinasesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2003Melony J. Black Abstract Modulation of calcium channel expression and function in the context of neurotrophin induced neuronal differentiation remains incompletely understood at a mechanistic level. We addressed this issue in the PC12 model neuronal system using patch clamp electrophysiology combined with ectopic expression of the human , platelet-derived growth factor (,PDGF) receptor as a surrogate neurotrophin receptor system. PC12 cells ectopically expressing the human ,PDGF receptor were treated with PDGF or nerve growth factor (NGF) for up to 7 days, and Ca2+ channel subtype expression was analyzed using selective pharmacological agents in both whole-cell and cell-attached single channel patch clamp configurations. PDGF-induced upregulation of N- and P/Q-type Ca2+ channel currents completely mimicked upregulation of these currents caused by NGF stimulation of the endogenous TrkA receptor tyrosine kinase (RTK). Neither PDGF nor NGF significantly altered L- or R-type currents. Single channel recordings together with immunocytochemistry implied that growth factor-induced increases in whole-cell Ca2+ currents were a result of synthesis of new channels, and that whereas increased N channel density was apparent in the soma, additional P/Q channels distributed preferentially to extrasomal locations, most likely the proximal neurites. Finally, specific signaling-deficient mutant forms of the ,PDGF receptor were used to show that activation of Src, PI3-kinase, RasGAP, PLC, or SHP-2 (some of which are implicated in certain other aspects of PC12 cell differentiation) by RTKs is not required for growth factor-induced Ca2+ channel upregulation. In contrast, activation of the Ras-related G-protein Rap1 was found critical to this process. © 2003 Wiley-Liss, Inc. [source] Ethanol Enhances the Interaction of Breast Cancer Cells Over-Expressing ErbB2 With FibronectinALCOHOLISM, Issue 5 2010Mei Xu Background:, Ethanol is a tumor promoter and may enhance the metastasis of breast cancer. However, the underlying cellular/molecular mechanisms remain unknown. Amplification of ErbB2 or HER2, a receptor tyrosine kinase of the ErbB family, is found in 20 to 30% of patients with breast cancer. We have previously demonstrated that the effect of ethanol on the migration/invasion of breast cancer cells positively correlated with the expression levels of ErbB2. Adhesion to the extracellular matrix (ECM) is an important initial step for cancer cell invasion and metastasis. In this study, we investigated the effects of ethanol on the adhesion of MCF7 breast cancer cells over-expressing ErbB2 (MCF7ErbB2) to human plasma fibronectin. Methods:, To test the hypothesis that ethanol may enhance the attachment of human breast cancer cells to fibronectin, an important component of the ECM, we evaluated the effect of ethanol on the expression of focal adhesions, cell attachment, and ErbB2 signaling in cultured MCF7ErbB2 cells. Results:, Exposure to ethanol drastically enhanced the adhesion of MCFErbB2 cells to fibronectin and increased the expression of focal adhesions. Ethanol induced phosphorylation of ErbB2 at Tyr1248, FAK at Tyr861, and cSrc at Try216. Ethanol promoted the interaction among ErbB2, FAK, and cSrc, and the formation of a focal complex. AG825, a selective ErbB2 inhibitor, attenuated the ethanol-induced phosphorylation of ErbB2 and its association with FAK. Furthermore, AG825 blocked ethanol-promoted cell/fibronectin adhesion as well as the expression of focal adhesions. Conclusions:, Our results suggest that ethanol enhances the adhesion of breast cancer cells to fibronectin in an ErbB2-dependent manner, and the FAK pathway plays an important role in ethanol-induced formation of a focal complex. [source] Quantitative mass spectrometry to investigate epidermal growth factor receptor phosphorylation dynamicsMASS SPECTROMETRY REVIEWS, Issue 1 2008Sven Schuchardt Abstract Identifying proteins of signaling networks has received much attention, because an array of biological processes are entirely dependent on protein cross-talk and protein,protein interactions. Protein posttranslational modifications (PTM) add an additional layer of complexity, resulting in complex signaling networks. Of particular interest to our working group are the signaling networks of epidermal growth factor (EGF) receptor, a transmembrane receptor tyrosine kinase involved in various cellular processes, including cell proliferation, differentiation, and survival. Ligand binding to the N -terminal residue of the extracellular domain of EGF receptor induces conformational changes, dimerization, and (auto)-phosphorylation of intracellular tyrosine residues. In addition, activated EGF receptor may positively affect survival pathways, and thus determines the pathways for tumor growth and progression. Notably, in many human malignancies exaggerated EGF receptor activities are commonly observed. An understanding of the mechanism that results in aberrant phosphorylation of EGF receptor tyrosine residues and derived signaling cascades is crucial for an understanding of molecular mechanisms in cancer development. Here, we summarize recent labeling methods and discuss the difficulties in quantitative MS-based phosphorylation assays to probe for receptor tyrosine kinase (RTK) activity. We also review recent advances in sample preparation to investigate membrane-bound RTKs, MS-based detection of phosphopeptides, and the diligent use of different quantitative methods for protein labeling. © 2007 Wiley Periodicals, Inc., Mass Spec Rev 27:51,65, 2008 [source] Development of anaplastic lymphoma kinase (ALK) small-molecule inhibitors for cancer therapyMEDICINAL RESEARCH REVIEWS, Issue 3 2008Rongshi Li Abstract Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase (RTK) involved in the genesis of several human cancers; indeed, ALK was initially identified in constitutively activated and oncogenic fusion forms,the most common being nucleophosmin (NPM)-ALK,in a non-Hodgkin's lymphoma (NHL) known as anaplastic large-cell lymphoma (ALCL) and subsequent studies identified ALK fusions in the human sarcomas called inflammatory myofibroblastic tumors (IMTs). In addition, two recent reports have suggested that the ALK fusion, TPM4-ALK, may be involved in the genesis of a subset of esophageal squamous cell carcinomas. While the cause-effect relationship between ALK fusions and malignancies such as ALCL and IMT is very well established, more circumstantial links implicate the involvement of the full-length, normal ALK receptor in the genesis of additional malignancies including glioblastoma, neuroblastoma, breast cancer, and others; in these instances, ALK is believed to foster tumorigenesis following activation by autocrine and/or paracrine growth loops involving the reported ALK ligands, pleiotrophin (PTN) and midkine (MK). There are no currently available ALK small-molecule inhibitors approved for clinical cancer therapy; however, recognition of the variety of malignancies in which ALK may play a causative role has recently begun to prompt developmental efforts in this area. This review provides a succinct summary of normal ALK biology, the confirmed and putative roles of ALK fusions and the full-length ALK receptor in the development of human cancers, and efforts to target ALK using small-molecule kinase inhibitors. © 2007 Wiley Periodicals, Inc. Med Res Rev, 28, No. 3, 372,412, 2008 [source] Fluorescence recovery after photobleaching and photoconversion in multiple arbitrary regions of interest using a programmable array microscope,MICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2009Guy M. Hagen Abstract Photomanipulation (photobleaching, photoactivation, or photoconversion) is an essential tool in fluorescence microscopy. Fluorescence recovery after photobleaching (FRAP) is commonly used for the determination of lateral diffusion constants of membrane proteins, and can be conveniently implemented in confocal laser scanning microscopy (CLSM). Such determinations provide important information on molecular dynamics in live cells. However, the CLSM platform is inherently limited for FRAP because of its inflexible raster (spot) scanning format. We have implemented FRAP and photoactivation protocols using structured illumination and detection in a programmable array microscope (PAM). The patterns are arbitrary in number and shape, dynamic and adjustable to and by the sample characteristics. We have used multispot PAM,FRAP to measure the lateral diffusion of the erbB3 (HER3) receptor tyrosine kinase labeled by fusion with mCitrine on untreated cells and after treatment with reagents that perturb the cytoskeleton or plasma membrane or activate coexpressed erbB1 (HER1, the EGF receptor EGFR). We also show the versatility of the PAM for photoactivation in arbitrary regions of interest, in cells expressing erbB3 fused with the photoconvertible fluorescent protein dronpa. dronpa. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc. [source] Melanoma development and pigment cell transformation in xiphophorusMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2002Claudia Wellbrock As early as 1927, it was recognised that hybridisation of platyfish (Xiphophorus maculatus) and swordtails (Xiphophorus helleri) results in offspring that develop tumours according to Mendelian laws. Most obviously, the primary event, namely the cell lineage-specific overexpression of a structurally altered receptor tyrosine kinase, finds its parallel in many tumours of birds and mammals. Once expressed at high levels, this receptor, the Xiphophorus melanoma inducing receptor kinase Xmrk, shows constitutive activation. By using different pathways, Xmrk induces both proliferative as well as anti-apoptotic signalling in pigment cells finally leading to cell transformation, tumour induction, and progression. Analyses of the different signalling cascades induced by the Xmrk-receptor led to the identification of the src-kinase Fyn, the MAP kinases ERK1 and ERK2, the "Signal Transducer and Activator of Transcription" STAT5, and the PI3-kinase as its major downstream substrates. This review describes some of the genetic findings, as well as the results from the recent molecular analyses of the factors involved in the initiation and manifestation of pigment cell transformation and melanoma development in Xiphophorus. Microsc. Res. Tech. 58:456,463, 2002. © 2002 Wiley-Liss, Inc. [source] Co-regulation of B-Myb expression by E2F1 and EGF receptor,MOLECULAR CARCINOGENESIS, Issue 1 2006Norihisa Hanada Abstract Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is frequently over-expressed in human cancers and is associated with tumorigenesis, and increased tumor proliferation and progression. Also found in breast tumors with high levels is B-Myb, a transcription factor whose expression is activated by E2F1/3 at the late G1 phase and the level is sustained through the S phase. Recent reports suggest a casual correlation between EGFR and B-Myb expression in primary breast carcinomas. However, the mechanism for such co-expression remains un-investigated. Here, we report that EGFR is important for B-Myb expression and the underlying mechanism involves cooperated effects from EGFR and E2F1. EGF stimulation and forced expression of EGFR significantly increase B-Myb gene activity and such increase occurs in the G1 phase. EGF-induced B-Myb expression was not significantly suppressed following inhibition of PI-3K and ERK, two major EGFR downstream pathways. In contrast, we observed EGF-induced in vivo association of nuclear EGFR to the B-Myb promoter and the association is only detected at the G1/S phase and is abolished by EGFR kinase inhibitor. As EGFR lacks DNA-binding domain but contains transactivational activity and E2F1 activates B-Myb expression in the G1/S phase, we further reasoned that nuclear EGFR might cooperate with E2F1 leading to activation of B-Myb. Indeed, we found that EGFR co-immunoprecipitated with E2F1 in an EGF-dependent manner and that EGF activated in vivo binding of E2F1 to the B-Myb promoter. Consistently, forced expression of both EGFR and E2F1 in EGFR-null CHO cells greatly enhanced B-Myb promoter activity, compared to the vector control and expression of EGFR or E2F1 alone. Promoter mutagenesis studies showed that EGF-induced activation of B-Myb promoter required both E2F and EGFR target sites. In summary, our data suggest that deregulated EGFR signaling pathway facilitate tumor cell proliferation partly via EGFR interaction with E2F1 and subsequent activation of B-Myb gene expression. © 2005 Wiley-Liss, Inc. [source] Selection for a dominant oncogene and large male size as a risk factor for melanoma in the Xiphophorus animal modelMOLECULAR ECOLOGY, Issue 15 2010ANDRÉ A. FERNANDEZ Abstract Adult height is a risk factor in numerous human cancers that involve aberrant receptor tyrosine kinase (RTK) signalling. However, its importance is debated due to conflicting epidemiological studies and the lack of useful in vivo models. In Xiphophorus fishes (Platyfishes/Swordtails), a functional RTK, Xiphophorus melanoma receptor kinase (Xmrk), serves as the dominant oncogene and has been maintained for several million years despite being deleterious and in an extremely unstable genomic region. Here we show that the Xmrk genotype is positively correlated with standard length in male and female wild caught Xiphophorus cortezi sampled throughout their phylogeographic distribution. Histopathology confirms the occurrence of malignant melanomas in both sexes; however, melanoma incidence was extremely male biased. Furthermore, males collected with malignant melanomas in the field were significantly larger than both Xmrk males collected without melanomas and wildtype (Xmrk deficient) males. These results not only provide a novel selective mechanism for the persistence of the germline Xmrk oncogene but also create an innovative avenue of melanoma research within the Xiphophorus fishes. Wildlife cancer in natural systems is a growing concern, therefore, future research investigating life history characteristics associated with certain phenotypes and genotypes that predispose an individual to cancer will be fundamental to increasing our understanding of the evolutionary biology of cancer in nature as well as in humans. [source] Stimulatory effects of the soy phytoestrogen genistein on noradrenaline transporter and serotonin transporter activityMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 4 2010Yumiko Toyohira Abstract We examined the effects of genistein, one of the major soy phytoestrogens, on the activity of noradrenaline transporter (NAT) and serotonin transporter. Treatment with genistein (10,nM,10,,M) for 20,min stimulated [3H]noradrenaline (NA) uptake by SK-N-SH cells. Genistein also stimulated [3H]NA uptake and [3H]serotonin uptake by NAT and serotonin transporter transiently transfected COS-7 cells, respectively. Kinetics analysis of the effect of genistein on NAT activity in NAT-transfected COS-7 cells revealed that genistein significantly increased the maximal velocity of NA transport with little or no change in the affinity. Scatchard analysis of [3H]nisoxetine binding to NAT-transfected COS-7 cells showed that genistein increased the maximal binding without altering the dissociation constant. Although genistein is also known to be an inhibitor of tyrosine kinases, daidzein, another soy phytoestrogen and an inactive genistein analogue against tyrosine kinases, had little effect on [3H]NA uptake by SK-N-SH cells. The stimulatory effects on NAT activity were observed by treatment of tyrphostin 25, an inhibitor of epidermal growth factor receptor tyrosine kinase, whereas orthovanadate, a protein tyrosine phosphatase inhibitor, suppressed [3H]NA uptake by NAT-transfected COS-7 cells. These findings suggest that genistein up-regulates the activity of neuronal monoamine transporters probably through processes involving protein tyrosine phosphorylation. [source] Na+/K+ATPase regulates sperm capacitation through a mechanism involving kinases and redistribution of its testis-specific isoformMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2010Larissa D. Newton Incubation of bovine sperm with ouabain, an endogenous cardiac glycoside that inhibits both the ubiquitous (ATP1A1) and testis-specific ,4 (ATP1A4) isoforms of Na+/K+ATPase, induces tyrosine phosphorylation and capacitation. The objectives of this study were to investigate: (1) fertilizing ability of bovine sperm capacitated by incubating with ouabain; (2) involvement of ATP1A4 in this process; and (3) signaling mechanisms involved in the regulation of sperm capacitation induced by inhibition of Na+/K+ATPase activity. Fresh sperm capacitated by incubating with ouabain (inhibits both ATP1A1 and ATP1A4) or with anti-ATP1A4 immunoserum fertilized bovine oocytes in vitro. Capacitation was associated with relocalization of ATP1A4 from the entire sperm head to the post-acrosomal region. To investigate signaling mechanisms involved in oubain-induced regulation of sperm capacitation, sperm preparations were pre-incubated with inhibitors of specific signaling molecules, followed by incubation with ouabain. The phosphotyrosine content of sperm preparations was determined by immunoblotting, and capacitation status of these sperm preparations were evaluated through an acrosome reaction assay. We inferred that Na+/K+ATPase was involved in the regulation of tyrosine phosphorylation in sperm proteins through receptor tyrosine kinase, nonreceptor type protein kinase, and protein kinases A and C. In conclusion, inhibition of Na+/K+ATPase induced tyrosine phosphorylation and capacitation through multiple signal transduction pathways, imparting fertilizing ability in bovine sperm. To our knowledge, this is the first report documenting both the involvement of ATP1A4 in the regulation of bovine sperm capacitation and that fresh bovine sperm capacitated by the inhibition of Na+/K+ATPase can fertilize oocytes in vitro. Mol. Reprod. Dev. 77: 136,148, 2010. © 2009 Wiley-Liss, Inc. [source] Immunohistochemical analysis of receptor tyrosine kinase signal transduction activity in chordomaNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 1 2008J. H. Fasig Aims: Currently, there are no effective chemotherapeutic protocols for chordoma. Reports of receptor tyrosine kinase (RTK) expression in chordoma suggest that these tumours may respond to kinase inhibitor therapy. However, RTK signalling activity has not been extensively investigated in chordoma. Methods: A tissue microarray containing 21 cases of chordoma was analysed for expression of a number of proteins involved in signal transduction from RTKs by immunohistochemistry. Results: Platelet-derived growth factor receptor-,, epidermal growth factor receptor (EGFR), KIT and HER2 were detected in 100%, 67%, 33% and 0% of cases, respectively. Platelet-derived growth factor receptor-, staining was of moderate-to-strong intensity in 20 of 21 cases. In contrast, KIT immunoreactivity was weak and focal in each of the seven positive cases. Total EGFR staining was variable; weak staining for phosphorylated EGFR was detected in nine cases. Phosphorylated isoforms of p44/42 mitogen-activated protein kinase, Akt and STAT3, indicative of tyrosine kinase activity, were detected in 86%, 76% and 67% of cases, respectively. Conclusions: Chordomas commonly express RTKs and activated signal transduction molecules. Although there were no statistically significant correlations between the expression of any of the markers studied and disease-free survival or tumour location, the results nonetheless indicate that chordomas may respond to RTK inhibitors or modulators of other downstream signalling molecules. [source] Activation of MET receptor tyrosine kinase in ulcer surface epithelial cells undergoing restitutionPATHOLOGY INTERNATIONAL, Issue 7 2008Miyuki Nagai No abstract is available for this article. [source] | |||||||||||||||||||||||||||||||||||||