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Cell surface receptors play major roles in the mobilization and homing of progenitor cells from the bone marrow to peripheral tissues. CXCR4 is an important receptor that regulates homing of leucocytes and endothelial progenitors in response to the chemokine stromal cell-derived factor-1 (SDF-1). Ionic calcium is also known to regulate chemotaxis of selective bone marrow cells (BMCs) through the calcium-sensing receptor, CaR. Here we show that calcium regulates CXCR4 expression and BMC responses to SDF-1. CaCl(2) treatment of BMC induced a time- and dose-dependent increase in both the transcription and cell surface expression of CXCR4. BMC subpopulations expressing VEGFR2(+), CD34(+) and cKit(+)/Sca-1(+) were especially sensitive to calcium. The effects were blocked by calcium influx inhibitors, anti-CaR antibody and the protein synthesis inhibitor cycloheximide, but not by the CXCR4 antagonist AMD3100. Calcium treatment also enhanced SDF-1-mediated CXCR4 internalization. These changes were reflected in significantly improved chemotaxis by SDF-1, which was abolished by AMD3100 and by antibody against CXCR4. Calcium pre-treatment improved homing of CD34(+) BMCs to ischemic muscle in vivo, and enhanced revascularization in ischemic mouse hindlimbs. Our results identify calcium as a positive regulator of CXCR4 expression that promotes stem cell mobilization, homing and therapy.
J Cell Mol Med 2009 Sep
PMID:Extracellular calcium increases CXCR4 expression on bone marrow-derived cells and enhances pro-angiogenesis therapy. 1922 May 81

To elucidate the molecular pathways that modulate renal cyst growth in ADPKD, we performed global gene profiling on cysts of different size (<1 ml, n = 5; 10-20 ml, n = 5; >50 ml, n = 3) and minimally cystic tissue (MCT, n = 5) from five PKD1 human polycystic kidneys using Affymetrix HG-U133 Plus 2.0 arrays. We used gene set enrichment analysis to identify overrepresented signaling pathways and key transcription factors (TFs) between cysts and MCT. We found down-regulation of kidney epithelial restricted genes (e.g. nephron segment-specific markers and cilia-associated cystic genes such as HNF1B, PKHD1, IFT88 and CYS1) in the renal cysts. On the other hand, PKD1 cysts displayed a rich profile of gene sets associated with renal development, mitogen-mediated proliferation, cell cycle progression, epithelial-mesenchymal transition, hypoxia, aging and immune/inflammatory responses. Notably, our data suggest that up-regulation of Wnt/beta-catenin, pleiotropic growth factor/receptor tyrosine kinase (e.g. IGF/IGF1R, FGF/FGFR, EGF/EGFR, VEGF/VEGFR), G-protein-coupled receptor (e.g. PTGER2) signaling was associated with renal cystic growth. By integrating these pathways with a number of dysregulated networks of TFs (e.g. SRF, MYC, E2F1, CREB1, LEF1, TCF7, HNF1B/ HNF1A and HNF4A), our data suggest that epithelial dedifferentiation accompanied by aberrant activation and cross-talk of specific signaling pathways may be required for PKD1 cyst growth and disease progression. Pharmacological modulation of some of these signaling pathways may provide a potential therapeutic strategy for ADPKD.
Hum Mol Genet 2009 Jul 01
PMID:Systems biology of autosomal dominant polycystic kidney disease (ADPKD): computational identification of gene expression pathways and integrated regulatory networks. 1934 36

The growth and metastasis of solid tumors is dependent on angiogenesis. The vascular endothelial growth factor (VEGF) and its cell surface receptor in human KDR (kinase domain containing receptor or VEGFR-2) have particular interest because of their importance in angiogenesis. The development of novel inhibitors of VEGFR-2 would be helpful to check the growth of tumors. Quantitative structure activity relationship (QSAR) analyses used to understand the structural factors affecting inhibitory potency of thiazole-substituted pyrazolone derivatives. Several pharmacophore-based models indicated the importance of steric, hydrophobic and hydrogen bond acceptor groups to inhibitory activity. The comparative molecular field analyses (CoMFA) and comparative molecular similarity indices analyses (CoMSIA) based 3D-QSAR models were derived using pharmacophore-based alignment. Both CoMFA (q(2)=0.70, r(2)=0.97 and r(predictive)(2)=0.61) and CoMSIA (q(2)=0.54, r(2)=0.82 and r(predictive)(2)=0.66) gave reasonable results. The molecular docking (receptor-guided technique) with a recently reported receptor structure (PDB=1YWN) were performed. The docked alignment was subsequently used for 3D-QSAR (CoMFA; q(2)=0.56, r(2)=0.97, r(predictive)(2)=0.82, CoMSIA; q(2)=0.58 r(2)=0.91, r(predictive)(2)=0.69). The overall both studies were indicated, steric, electrostatic and hydrogen bond acceptor effects contribute to the inhibitory activity. CoMFA and CoMSIA models suggested that a positive bulk with hydrophobic effect is desirable around position 4 and 5 and hydrogen bond acceptor groups around pyrazolones ring will be helpful.
J Mol Graph Model 2009 Aug
PMID:Pharmacophore and docking-based combined in-silico study of KDR inhibitors. 1944 57

On vascular endothelial growth factor (VEGF) stimulation, both VEGF R1 and R2 receptors were phosphorylated in ovine fetoplacental artery endothelial (oFPAE) cells. Treatment with VEGF stimulated both time- and dose-dependent activation of ERK2/1 in oFPAE cells. VEGF-induced ERK2/1 activation was mediated by VEGFR2, but not VEGFR1, and was linked to intracellular calcium, protein kinase C, and Raf-1. VEGF stimulated oFPAE cell proliferation, migration, and tube formation in vitro. Blockade of ERK2/1 pathway attenuated VEGF-induced cell proliferation and tube formation but failed to inhibit migration in oFPAE cells. Disruption of caveolae by cholesterol depletion with methyl-beta-cyclodextrin or by down-regulation of its structural protein caveolin-1 blunted VEGF-induced ERK2/1 activation, proliferation, and tube formation in oFPAE cells, indicating an essential role of integral caveolae in these VEGF-induced responses. Adenoviral overexpression of caveolin-1 and addition of a caveolin scaffolding domain peptide also inhibited VEGF-stimulated ERK2/1 activation, cell proliferation, and tube formation in oFPAE cells. Furthermore, molecules comprising the ERK2/1 signaling module, including VEGFR2, protein kinase Calpha, Raf-1, MAPK kinase 1/2, and ERK2/1, resided with caveolin-1 in caveolae. VEGF transiently stimulated ERK2/1 activation in the caveolae similarly as in intact cells. Caveolae disruption greatly diminished ERK2/1 activation by VEGF in oFPAE cell caveolae. We conclude that caveolae function as a platform for compartmentalizing the VEGF-induced ERK2/1 signaling module. Caveolin-1 and caveolae play a paradoxical role in regulating VEGF-induced ERK2/1 activation and in vitro angiogenesis as evidenced by the similar inhibitory effects of down-regulation and overexpression of caveolin-1 and disruption of caveolae in oFPAE cells.
Mol Endocrinol 2009 Sep
PMID:Compartmentalizing VEGF-induced ERK2/1 signaling in placental artery endothelial cell caveolae: a paradoxical role of caveolin-1 in placental angiogenesis in vitro. 1947 52

Angiogenesis, the development of new blood vessel from pre-existing vessels, is a key process in the formation of the granulation tissue during wound healing. The appropriate development of new blood vessels, along with their subsequent maturation and differentiation, establishes the foundation for functional wound neovasculature. We performed studies in vivo and used a variety of cellular and molecular approaches in vitro to show that insulin stimulates angiogenesis and to elucidate the signalling mechanisms by which this protein stimulates microvessel development. Mice skin injected with insulin shows longer vessels with more branches, along with increased numbers of associated alpha-smooth muscle actin-expressing cells, suggesting the appropriate differentiation and maturation of the new vessels. We also found that insulin stimulates human microvascular endothelial cell migration and tube formation, and that these effects occur independently of VEGF/VEGFR signalling, but are dependent upon the insulin receptor itself. Downstream signalling pathways involve PI3K, Akt, sterol regulatory element-binding protein 1 (SREBP-1) and Rac1; inhibition of these pathways results in elimination of endothelial cell migration and tube formation and significantly decreases the development of microvessels. Our findings strongly suggest that insulin is a good candidate for the treatment of ischaemic wounds and other conditions in which blood vessel development is impaired.
J Cell Mol Med
PMID:Cell and molecular mechanisms of insulin-induced angiogenesis. 1960 55

Delphinidin has been reported to inhibit EGFR signalling. To determine whether other receptor tyrosine kinases (RTKs) are also influenced by delphinidin, we examined its ability to inhibit the kinase activity of EGFR, ErbB2, VEGFR-2, VEGFR-3 and IGF1R in a cell-free test system. We found that delphinidin strongly inhibited the protein tyrosine kinase activity of all tested RTKs at low micromolar concentrations. In A431 and PAE cells, ligand-induced phosphorylation of the receptors was also potently suppressed, with a preference for the suppression of the activity of ErbB3 (IC(50) approximately 100 nM) and VEGFR-3 (IC(50) < 50 microM). Thus the inhibition of RTKs by delphinidin is not limited to cell-free assays but is also of relevance in the cellular context. The results indicate that delphinidin acts as a broad-spectrum inhibitor of RTKs. Given the crucial role of the receptors in tumour growth and metastasis, we conclude that delphinidin has the potential to act directly against tumour cells as well as to interfere with key tumour-host interactions, although the suitability of delphinidin as a drug in cancer management may be compromised by its limited stability. Nevertheless, delphinidin may represent a novel lead compound for the development of chemopreventative and chemotherapeutic intervention strategies.
Mol Nutr Food Res 2009 Sep
PMID:Delphinidin inhibits a broad spectrum of receptor tyrosine kinases of the ErbB and VEGFR family. 1965 23

The effect of vascular endothelial growth factor (VEGF) ligands and cediranib on tumor cell proliferation, migration, and invasion was determined. It has recently been suggested that autocrine signaling through the VEGF receptor (VEGFR) pathway may play a role in tumor cell survival, invasion, and migration. The purpose of the present study was to determine the expression of VEGFRs and VEGFR ligands in a panel of gastrointestinal carcinoma cells. Additionally, we evaluated the effects of VEGF autocrine signaling on tumor cell proliferation, migration, and invasion utilizing cediranib (AZD2171), a pan-VEGFR inhibitor. Five colorectal, three pancreatic, and two hepatocellular carcinoma cell lines were screened for VEGFR and VEGF expression by several methods. Expression of VEGFR-1 and VEGFR-3 was cell line-dependent, whereas VEGFR-2 was not detected. Secretion of VEGF-A was detected in the supernatants of all cell lines whereas VEGF-C secretion was detected in the Panc-1, MiaPaca2, and Hep1 cells only. Tumor cells showed increased migratory activity, but not proliferation, when stimulated with VEGFs. The pan-VEGFR inhibitor cediranib (100 nmol/L) inhibited tumor cell migration and invasion, with no effects on proliferation. Cediranib decreased VEGFR-1 and VEGFR-3 phosphorylation as well as activation of downstream effectors. VEGFR-1 and VEGFR-3 expression was detected in all the gastrointestinal carcinoma cells evaluated. Although activation of the VEGF pathway did not affect cell proliferation, our data indicate that this pathway seems to play a role in tumor cell migration and invasion in these cell lines. Therefore, inhibition of VEGFR by cediranib may represent a clinically relevant treatment option for gastrointestinal tumors.
Mol Cancer Ther 2009 Sep
PMID:Targeting vascular endothelial growth factor receptor-1 and -3 with cediranib (AZD2171): effects on migration and invasion of gastrointestinal cancer cell lines. 1975 10

Infiltration of bone marrow derived cells is part of the angiogenic switch required for uncontrolled tumour growth. However, the nature of the tumour-infiltrating cells from bone marrow has not been fully elucidated. To investigate the phenotype of bone marrow derived cells within a tumour, we employed the Lewis lung carcinoma (LLC) murine tumour model. We followed bone marrow derivation of tumour-infiltrating cells through transplantation of CD45.2 bone marrow cells into pre-irradiated CD45.1 mice. We found robust CD45.2 donor type chimerism in bone marrow and blood of CD45.1 recipient tumour-bearing mice. Flow cytometric analysis of LLC tumours showed, in addition to previously described pro-angiogenic CD45(+)VEGFR2(+)'endothelial progenitor cells' (EPC), or CD45(+)Tie2(+)'Tie2-expressing monocytes' (TEM), incorporation of donor type lineage marker negative (Lin(-)) and Lin(-)Sca1(+) undifferentiated haematopoietic cell types. Immunohistochemical analysis confirmed the extravasal location of the primitive haematopoietic cells. Flow-cytometric sorting of bone marrow cells and subsequent analysis in haematopoietic colony-forming assays revealed that cells with a Lin(-)Sca1(+) phenotype, which were initially negative for VEGFR2 and Tie2, gave rise to VEGFR2(+) and/or Tie2(+) cells. Moreover, Lin(-) bone marrow cells pre-labelled with the membrane dye PKH26 (a red fluorochrome) and transplanted i.v. into tumour-bearing mice were found to extravasate and incorporate into LLC tumours within 24 hrs. Thus, primitive haematopoietic precursors which are thought to be precursors of EPC and TEMs, constitute a part of the tumour microenvironment. This makes them an attractive target cell population for tumour-directed cellular therapies.
J Cell Mol Med 2010 Jul
PMID:Bone marrow derived cells in the tumour microenvironment contain cells with primitive haematopoietic phenotype. 1976 71

Targeted mAbs to VEGFR and EGFR are well-established therapies for the treatment of colorectal cancer. The costs and toxicities associated with these novel treatments are not insignificant, and therefore molecular markers that predict treatment efficacy are needed to individualize the therapy administered to each patient. Recent data in this research field support KRAS mutation testing to guide the selection of EGFR inhibitors for the treatment of colorectal cancer. This review discusses the evidence that KRAS mutation analysis can indicate a beneficial response to EGFR inhibitors, and the potential and limitations of other mutations in the VEGF and EGF signaling pathways as predictive molecular markers in this setting.
Curr Opin Mol Ther 2009 Dec
PMID:Predictive biomarkers of clinical response to targeted antibodies in colorectal cancer. 2007 38

Farnesiferol C (FC) is one of the major compounds isolated from Ferula assafoetida, an Asian herbal spice used for cancer treatment as a folk remedy. Here, we examined the hypothesis that novel antiangiogenic activities of FC contribute to anticancer efficacy. In human umbilical vein endothelial cells (HUVEC), exposure to the 10 to 40 mumol/L concentration range of FC inhibited vascular endothelial growth factor (VEGF)-induced cell proliferation, migration, invasion, tube formation, and the expression of matrix metalloproteinase-2. In addition, FC inhibited the angiogenic sprouting of VEGF-treated rat aorta in an ex vivo model. Furthermore, FC inhibited the in vivo growth of mouse Lewis lung cancer allograft model by 60% (P < 0.001) at a daily i.p. dosage of 1 mg/kg body weight without any negative effect on the weight of the host mice. Immunohistochemistry staining showed decreased microvessel density (CD34) and proliferative index (Ki-67) without affecting the apoptotic (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) index. Mechanistically, FC decreased the binding of VEGF to VEGFR1/Flt-1, but not to VEGFR2/KDR/Flk-1. In terms of early signaling, FC exerted a rapid inhibitory action (examined within 10 minutes) on VEGF-induced autophosphorylation of VEGFR1 without affecting that of VEGFR2. Nevertheless, FC decreased the phosphorylation of most of the kinases downstream of VEGFR2: focal adhesion kinase, Src, extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and c-jun-NH(2)-kinase without affecting AKT. Computer simulation suggests that FC may inhibit Src or focal adhesion kinase protein activities directly through its docking to their ATP-binding sites. Taken together, the multitargeting actions of FC, particularly VEGFR1 inhibition, may make it a novel drug candidate to complement current VEGF/VEGFR2-targeting antiangiogenic modalities for cancer.
Mol Cancer Ther 2010 Feb
PMID:Herbal compound farnesiferol C exerts antiangiogenic and antitumor activity and targets multiple aspects of VEGFR1 (Flt1) or VEGFR2 (Flk1) signaling cascades. 2010 98


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