Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The L-type Ca(2+) channel is the primary voltage-dependent Ca(2+)-influx pathway in many excitable and secretory cells, and direct phosphorylation by different kinases is one of the mechanisms involved in the regulation of its activity. The aim of this study was to evaluate the participation of Ser/Thr kinases and tyrosine kinases (TKs) in depolarization-induced Ca(2+) influx in the endocrine somatomammotrope cell line GH3. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured using a spectrofluorometric method with fura 2-AM, and 12.5 mM KCl (K(+)) was used as a depolarization stimulus. K(+) induced an abrupt spike (peak) in [Ca(2+)](i) that was abolished in the presence of nifedipine, showing that K(+) enhances [Ca(2+)](i), preferably activating L-type Ca(2+) channels. H89, a selective PKA inhibitor, significantly reduced depolarization-induced Ca(2+) mobilization in a concentration-related manner when it was applied before or after K(+), and okadaic acid, an inhibitor of Ser/Thr phosphatases, which has been shown to regulate PKA-stimulated L-type Ca(2+) channels, increased K(+)-induced Ca(2+) entry. When PKC was activated by PMA, the K(+)-evoked peak in [Ca(2+)](i), as well as the plateau phase, was significantly reduced, and chelerythrine (a PKC inhibitor) potentiated the K(+)-induced increase in [Ca(2+)](i), indicating an inhibitory role of PKC in voltage-dependent Ca(2+) channel (VDCC) activity. Genistein, a TK inhibitor, reduced the K(+)-evoked increase in [Ca(2+)](i), but, unexpectedly, the tyrosine phosphatase inhibitor orthovanadate reduced not only basal Ca(2+) levels but, also, Ca(2+) influx during the plateau phase. Both results suggest that different TKs may act differentially on VDCC activation. Activation of receptor TKs with epidermal growth factor (EGF) or vascular endothelial growth factor potentiated K(+)-induced Ca(2+) influx, and AG-1478 (an EGF receptor inhibitor) decreased it. However, inhibition of the non-receptor TK pp60 c-Src enhanced K(+)-induced Ca(2+) influx. The present study strongly demonstrates that a complex equilibrium among different kinases and phosphatases regulates VDCC activity in the pituitary cell line GH3: PKA and receptor TKs, such as vascular endothelial growth factor receptor and EGF receptor, enhance depolarization-induced Ca(2+) influx, whereas PKC and c-Src have an inhibitory effect. These kinases modulate membrane depolarization and may therefore participate in the regulation of a plethora of intracellular processes, such as hormone secretion, gene expression, protein synthesis, and cell proliferation, in pituitary cells.
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PMID:Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells. 1750 32

Sorafenib, a novel drug for metastatic renal cancer, has broad-spectrum activity against multiple tyrosine kinases, including Raf-1, vascular endothelial growth factor receptor and platelet-derived growth factor receptor. However, little is known about its effects on the immune system. In this report, we examine the effects of sorafenib on the proliferation and activation of human peripheral blood T cells, as well as its effects on T-cell-mediated immune response in mice. At concentrations similar to those used in patients, sorafenib inhibited the proliferation of primary human T cells in vitro. At more than 10 microM, sorafenib caused an irrecoverable inhibition of proliferation, even after drug withdrawal. In addition, sorafenib induced T-cell apoptosis at concentrations higher than 10 muM. sorafenib also caused G(0)/G(1) phase arrest, inhibition of CD25 and CD69 expression, interleukin-2 production and LCK phosphorylation in the T cells; all of these effects exhibited dose and time dependence. When tested against contact dermatitis in mice, sorafenib significantly reduced the ear swelling induced by picryl chloride. These findings suggest that sorafenib may cause the loss of T-cell immune response by inducing apoptosis and targeting LCK. This could potentially lead to immunosuppression in patients with cancer.
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PMID:Sorafenib inhibits activation of human peripheral blood T cells by targeting LCK phosphorylation. 1833 60

Angiogenesis, the formation of new blood vessels, plays a crucial role in normal physiological processes and in various pathological conditions. In the present study, we have investigated the physiological function of a newly described serine/threonine protein kinase D2 (PKD2) in aspects of endothelial cell biology involved in angiogenesis. We found that PKD2 was expressed in primary human endothelial cells from different tissues and was a critical PKD isoform mediating the phosphorylation of PKD substrates in endothelial cells. By using small interference RNAs that target different PKD2 regions, we found that silencing PKD2, but not PKD1 isoform, markedly inhibited the proliferation, migration, and in vitro angiogenesis of endothelial cells cultured in EGM-2 complete medium. We further showed that PKD2, but not PKD1, was required for the expression of vascular endothelial growth factor receptor-2 and fibroblast growth factor receptor-1 that are two key growth factor receptors involved in angiogenesis. These findings indicate that PKD2 plays a pivotal role in endothelial cell proliferation and migration necessary for angiogenesis at least in part through modulation of the expression of vascular endothelial growth factor receptor-2 and fibroblast growth factor receptor-1.
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PMID:Identification of protein kinase D2 as a pivotal regulator of endothelial cell proliferation, migration, and angiogenesis. 1900 81

Protein kinases catalyse key phosphorylation reactions in signalling cascades that affect every aspect of cell growth, differentiation and metabolism. The kinases have become prime targets for drug intervention in the diseased state, especially in cancer. There are currently 10 drugs that have been approved for clinical use and many more in clinical trials. This review summarises the structural basis for protein kinase inhibition and discusses the mode of action for each of the approved drugs in the light of structural results. All but one of the approved compounds target the ATP binding site on the kinase. Both the active and inactive conformations of protein kinases have been used in strategies to produce potent and selective compounds. Targeting the inactive conformation can give high specificity. Targeting the active conformation is favourable where the diseased state has arisen from activating mutations, but such inhibitors generally target several protein kinases. Drug resistance mutations are a potential risk for both conformational states, where drug-binding regions are not directly involved in catalysis. Imatinib (Glivec), the most successful of protein kinase inhibitors, targets the inactive conformation of ABL tyrosine kinase. Newer compounds, such as dasatinib, which targets the ABL active state, have been developed to increase potency and have proved effective for some, but not all, drug-resistant mutations. The first epidermal growth factor receptor (EGFR) inhibitors in clinical use [gefitinib (Iressa) and erlotinib (Tarceva)] targeted the active form of the kinase, and this proved advantageous for patients whose cancer was caused by mutations that resulted in a constitutively active EGFR kinase domain. Newer approved compounds, such as lapatinib (Tykerb), target the inactive conformation with high potency. A further compound that forms a covalent attachment to the kinase has been found to overcome one of the major drug resistance mutations, where the effectiveness of the drug in vivo is dependent on its ability to compete successfully in the presence of cellular concentrations of ATP. Inhibitors of vascular endothelial growth factor receptor (VEGFR) kinase against cancer angiogenesis show the advantage of some relaxation in specificity. Sorafenib, originally developed as RAF inhibitor, is now in clinical use as a VEGFR inhibitor. Temsirolimus (a derivative of rapamycin) is the only example of a drug in clinical use that does not target the kinase ATP site. Instead rapamycin, when in complex with the protein FKBP12, effectively targets mTOR kinase at a site located on a domain, the FRB domain, that appears to be involved in localisation or substrate docking.
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PMID:Protein kinase inhibitors: contributions from structure to clinical compounds. 1929 66

Progression in pediatric brain tumor growth is thought to be the net result of signaling through various protein kinase-mediated networks driving cell proliferation. Defining new targets for treatment of human malignancies, without a priori knowledge on aberrant cell signaling activity, remains exceedingly complicated. Here, we introduce kinome profiling using flow-through peptide microarrays as a new concept for target discovery. Comprehensive tyrosine kinase activity profiles were identified in 29 pediatric brain tumors using the PamChip kinome profiling system. Previously reported activity of epidermal growth factor receptor, c-Met, and vascular endothelial growth factor receptor in pediatric brain tumors could be appreciated in our array results. Peptides corresponding with phosphorylation consensus sequences for Src family kinases showed remarkably high levels of phosphorylation compared with normal tissue types. Src activity was confirmed applying Phos-Tag SDS-PAGE. Furthermore, the Src family kinase inhibitors PP1 and dasatinib induced substantial tumor cell death in nine pediatric brain tumor cell lines but not in control cell lines. Thus, this study describes a new high-throughput technique to generate clinically relevant tyrosine kinase activity profiles as has been shown here for pediatric brain tumors. In the era of a rapidly increasing number of small-molecule inhibitors, this approach will enable us to rapidly identify new potential targets in a broad range of human malignancies.
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PMID:Kinome profiling in pediatric brain tumors as a new approach for target discovery. 1956 81

The approval of a multitargeted receptor tyrosine kinase inhibitor, sorafenib, with activity against vascular endothelial growth factor receptor-2 and -3, Raf-1 and B-Raf, platelet-derived growth factor receptor-alpha and -beta, and other kinases, has ushered in the era of molecular targeted agents in advanced hepatocellular carcinoma (HCC). Sunitinib malate is an oral, multitargeted inhibitor of vascular endothelial growth factor receptor-1, -2, and -3, platelet-derived growth factor receptor-alpha and -beta, and other kinases implicated in tumor growth, angiogenesis, and metastasis. Sunitinib has been approved in metastatic renal cell carcinoma and gastrointestinal stromal tumor and is undergoing active clinical development in HCC. Early evidence of antitumor activity and a promising safety profile for this agent have emerged from single arm phase II trials in United States, European, and Asian patients with advanced HCC. Correlative studies of imaging and circulating biomarkers have provided insights into the potential mechanism of action of sunitinib. Additional phase II studies using either single agent or in combination with chemotherapeutic agents are ongoing, and a phase III trial comparing sunitinib and sorafenib in advanced HCC is actively accruing patients. Here, we review the current progress and future directions for the development of sunitinib in advanced HCC.
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PMID:Development of sunitinib in hepatocellular carcinoma: rationale, early clinical experience, and correlative studies. 1967 41

Hepatocellular carcinoma (HCC) is a major global health problem, which has a grave morbidity and mortality. Over the past few decades, no effective systemic therapeutic modalities have been established for patients with the unresectable HCC in advanced stage. Sorafenib is a small molecule that blocks cancer cell proliferation by targeting the intracellular signaling pathway at the level of Raf-1 and B-Raf serine-threonine kinases, and exerts an anti-angiogenic effect by targeting the vascular endothelial growth factor receptor-1, 2 and 3, and platelet-derived growth factor receptor-beta tyrosine kinases. Recently, two clinical successful applications, SHARP and Asia-Pacific trial, of multikinase inhibitor sorafenib represent a significant advance in the treatment of advanced HCC patients without a curative chance. However, because the results of clinical trials show diverse responses in a subset of HCC patients, a molecular classification of HCC through the excavation of specific biomarkers related to its biological behavior is necessary for sorting HCC patients to each group with a biological homogeneity, ultimately leading to the most suitable individualization of molecular targeted therapy in HCC.
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PMID:Molecular targeting for treatment of advanced hepatocellular carcinoma. 1978 79

Sorafenib (Nexavar) is a novel oral Raf kinase and vascular endothelial growth factor receptor inhibitor. Most anticancer drugs are substrates for ATP-binding cassette efflux pumps especially for P-glycoprotein (P-gp). To evaluate the influence of P-gp on the pharmacokinetics of sorafenib substrate properties for this transporter were investigated. Therefore, permeability of sorafenib across Caco-2 and P-gp-overexpressing cells was determined. To determine the in vivo relevance of these in vitro findings, pharmacokinetics of sorafenib in mdr1a/1b(-/-) and wild-type (WT) mice was studied. Sorafenib is highly permeable and exhibits a slight efflux across Caco-2 cells. In P-gp-overexpressing cells, a small concentration-dependent efflux was observed, which was completely blocked by the addition of ivermectin. In mdr1a/1b(-/-) and WT mice, unchanged compound represented by far the majority of radioactivity in plasma. After intravenous and oral administration, brain/plasma concentration ratios in mdr1a/1b(-/-) mice were 1.3- to 1.5-fold higher than those in WT mice. However, after intravenous or oral administration, plasma concentrations were similar in both mouse strains. In conclusion, sorafenib is highly permeable and a weak P-gp substrate in vitro. These findings were confirmed by the small factor of 1.3 to 1.5 observed for the brain/plasma ratios in mdr1a/1b(-/-) versus WT mice in vivo. Based on these in vitro and in vivo results, it is unlikely that P-gp has a major effect on the plasma concentrations of sorafenib in humans. Because of the high permeability and low P-gp-mediated transport, sorafenib might be able to cross the blood-brain barrier and target tumors within the brain.
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PMID:In vitro to in vivo comparison of the substrate characteristics of sorafenib tosylate toward P-glycoprotein. 2041 26

One essential downstream signaling pathway of receptor tyrosine kinases (RTKs), such as vascular endothelial growth factor receptor (VEGFR) and the Tie2 receptor, is the phosphoinositide-3 kinase (PI3K)-phosphoinositide-dependent protein kinase 1 (PDK1)-Akt/protein kinase B (PKB) cascade that plays a critical role in development and tumorigenesis. However, the role of PDK1 in cardiovascular development remains unknown. Here, we deleted PDK1 specifically in endothelial cells in mice. These mice displayed hemorrhage and hydropericardium and died at approximately embryonic day 11.5 (E11.5). Histological analysis revealed defective vascular remodeling and development and disrupted integrity between the endothelium and trabeculae/myocardium in the heart. The atrioventricular canal (AVC) cushion and valves failed to form, indicating a defect in epithelial-mesenchymal transition (EMT), together with increased endothelial apoptosis. Consistently, ex vivo AVC explant culture showed impeded mesenchymal outgrowth. Snail protein was reduced and was absent from the nucleus in AVC cells. Delivery of the Snail S6A mutant to the AVC explant effectively rescued EMT defects. Furthermore, adenoviral Akt delivery rescued EMT defects in AVC explant culture, and deletion of PTEN delayed embryonic lethality of PDK1 endothelial deletion mice by 1 day and rendered normal development of the AVC cushion in the PDK1-deficient heart. Taken together, these results have revealed an essential role of PDK1 in cardiovascular development through activation of Akt and Snail.
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PMID:PDK1 regulates vascular remodeling and promotes epithelial-mesenchymal transition in cardiac development. 2045 9

Increasing evidence suggests that myeloid bone marrow-derived cells (BMDCs) play a critical role in lung metastasis. Blockade of VEGF receptor 1 (VEGFR1) has been proposed as a potential strategy to limit myeloid BMDC recruitment to tumors. However, preclinical evidence indicates that this strategy may not be effective in all tumors. Thus, establishing which molecular mechanisms are responsible for the "escape" of these BMDCs from VEGFR1 inhibition would facilitate development of strategies to control metastasis. Here, we report the complementary role of the chemokine (C-X-C motif) ligand 12/C-X-C chemokine receptor 4 (CXCR4) and VEGF/VEGFR1 pathways in promoting lung metastasis in mice via BMDC recruitment using chimeric mice with deficiency in CXCR4 and VEGFR1-tyrosine kinase in the BMDCs. We first demonstrate that CXCR4 activity is essential for recruitment of myeloid differentiation antigen (Gr-1)-positive BMDCs, whereas VEGFR1 activity is responsible for macrophage recruitment in established tumors. Inhibition of both VEGFR1 and CXCR4 signaling in myeloid BMDCs exerted greater effects on tumor vascular density, growth, and lung metastasis than inhibition of VEGFR1 alone. These effects were reproduced after pharmacologic inhibition of CXCR4 with AMD3100. VEGFR1 and CXCR4 independently exerted a promigratory effect in myeloid BMDCs by activating p38 mitogen-activating protein kinase. Thus, combining CXCR4 blockade with inhibition of VEGFR1 may induce greater tumor growth delay and prevent or inhibit metastasis.
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PMID:C-X-C receptor type 4 promotes metastasis by activating p38 mitogen-activated protein kinase in myeloid differentiation antigen (Gr-1)-positive cells. 2117 23


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