Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0677930 (primary tumor)
 20,210 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Normal human melanocytes and five human melanoma cell lines were analyzed for production of platelet-derived growth factor (PDGF)-like activity. Three of the melanoma cell lines released an activity that inhibited binding of 125I-labeled PDGF to human foreskin fibroblasts and stimulated [3H]thymidine incorporation in such cells. These activities were inhibited by the addition of anti-PDGF antibodies. All three factor-producing cell lines were derived from the same patient--one originated from the primary tumor (WM 115), and two were from individual lymph-node metastases (WM 239A and WM 266-4). The factor produced by WM 266-4 cells was characterized biochemically in detail. Immunoprecipitated, the metabolically labeled factor migrated in NaDod-SO4/gel electrophoresis as a homogeneous Mr 31,000 species, which under reducing conditions was resolved into two species of Mr 16,500 and Mr 17,000, implying a dimeric structure of the molecule. The factor was purified to homogeneity. Analysis by reverse-phase high-pressure liquid chromatography of reduced and alkylated factor revealed an elution pattern identical to that of PDGF A chains. Thus, the native molecule appears to be a homodimer of PDGF A chains. Blot-hybridization analysis of poly(A)+ RNA from the cell lines with 32P-labeled PDGF A chain and B chain (SIS product) cDNA probes revealed a relative abundance of B chain transcripts in the cell line originating from the primary tumor tissue only but expression of A chain in all three cell lines. We conclude that the two structural genes encoding each of the subunit chains of PDGF can be expressed in human melanoma cells and that the two genes can be independently expressed in such cells.
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PMID:Human melanoma cell lines of primary and metastatic origin express the genes encoding the chains of platelet-derived growth factor (PDGF) and produce a PDGF-like growth factor. 302 May 39

The role of platelets in cancer metastasis was studied by investigating the effects of the antiplatelet agents ticlopidine, diltiazem, dipyridamole and trapidil on artificial and spontaneous pulmonary metastases in mice. These agents were tested at their optimal inhibitory doses on adenosine diphosphate-induced platelet aggregation; namely, 100 mg/kg for ticlopidine, 2 mg/kg for diltiazem, 180 mg/kg for trapidil and 60 mg/kg for dipyridamole. At these doses, trapidil caused moderate inhibition of thrombin-induced platelet aggregation in mice, but the other agents had only slight effects. Artificial pulmonary metastasis was produced by inoculation of Lewis lung carcinoma (LLC) or B16 melanoma (B16) cells into C57BL/6 mice. For induction of spontaneous pulmonary metastases, these tumor cells were implanted subcutaneously into the footpads of mice. The resulting primary tumors of LLC and B16 were removed 9-10 and 17 days later, respectively. Artificial pulmonary metastases were inhibited significantly by all the antiplatelet agents tested. Spontaneous pulmonary metastases were markedly reduced only when these agents were given after removal of the primary tumor. The role of platelets is discussed with respect to thrombus formation in the lodgement of tumor cells and the participation of platelet-derived growth factor in the growth of metastatic foci.
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PMID:Effects of antiplatelet agents on pulmonary metastases. 672 29

We used standard karyotypic analyses of first-division cells to identify a subpopulation of cells in primary malignant gliomas with over-representation of chromosomes 7 and 22. These cells are a minor subpopulation in the primary tumor but become the dominant population after treatment in vitro of the cells with the chemotherapeutic agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). The selection for a cell with this specific karyotypic abnormality suggests that these chromosomes contain genes important to the growth of BCNU-resistant cells. Southern blot hybridization analyses demonstrate an increased copy number of the genes encoding platelet-derived growth factor (PDGF) A-chain and B-chain, which have been mapped to chromosomes 7 and 22, respectively. Reverse transcription followed by polymerase chain reaction (RT-PCR) analysis demonstrates increased expression of these genes. In addition, these cells secrete a mitogenic factor that stimulates 3H-thymidine uptake in NIH 3T3 cells. This factor is sensitive to anti-PDGF antibodies and beta-mercaptoethanol, but not to anti-EGF antibodies. These data suggest that autocrine and/or paracrine mechanisms occur in human malignant gliomas, and that over-expression of PDGF may play a role in the growth of BCNU-resistant cells in these tumors.
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PMID:BCNU-resistant human glioma cells with over-representation of chromosomes 7 and 22 demonstrate increased copy number and expression of platelet-derived growth factor genes. 750 21

Cancer has been proposed to develop by a process of stepwise accumulation of growth-advantageous genetic alterations which result in the evolution of clones which are outgrowths of such rare cells [1]. This model has recently been extensively tested in human gliomas, the most common primary tumor of the adult central nervous system. Temporal disease progression involves an interplay between growth-suppressing and growth-promoting genes. Specifically for gliomas, genetic studies have indicated loss of germline heterozygosity for chromosome 17p; mutation of the p53 gene; overexpression of the platelet-derived growth factor-alpha receptor; allelic losses of chromosomes 22q, 13q, and 19q; deletion of the interferon-alpha and beta and CDKN2 loci on chromosome 9p; amplification and rearrangement of the epidermal growth factor receptor gene, and monosomy of chromosome 10. The following discussion details these genetic alterations and their consequences for the biology of glioma progression with the ultimate aim of providing new avenues for clinical intervention.
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PMID:Molecular biology of malignant degeneration of astrocytoma. 881 14

Amplification and/or mutations of the epidermal growth factor (EGF) receptor have been frequently reported in human malignant gliomas, the most common primary tumor of the adult central nervous system. We have analyzed a panel of established human glioma cell lines for EGF receptor expression. The EGF receptor was expressed in all of the glioma cell lines tested, with highest levels found in the cell line U343MG-a. In addition, various amounts of a truncated form of the EGF receptor were detected. The platelet-derived growth factor (PDGF) alpha receptor, analyzed for comparison, was expressed at low levels in human glioma cells, with the exception of U-118MG and U-373MG cells. The truncated form of the EGF receptor has been discussed as a constitutively active variant of the receptor. Using antibodies directed against the active form of the EGF receptor, we show here that the truncated variant of the EGF receptor in U343MG-a cells is not in the active conformation. However, the full-length EGF receptor, highly expressed in U343MG-a cells, was very rapidly activated following EGF treatment. In line with this, phosphorylation and activation of the mitogen-activated protein kinase/extracellular signal-regulated protein kinase (ERK) in U343MG-a cells required administration of EGF. Moreover, using highly specific riboprobes we observed that EGF signaling increased the Egr-1 mRNA concentration in human glioma cells within 30 min. The increase in the Egr-1 mRNA concentration was followed by a transient synthesis of the Egr-1 protein. Likewise, Egr-1 mRNA and protein concentrations were increased in U-118MG and U-373MG cells treated with PDGF. The synthesis of Egr-1 in human glioma cells as a result of EGF or PDGF stimulation indicates that Egr-1 may be an important "late" part of the EGF and PDGF-initiated signaling cascades suggesting that Egr-1 functions as a "third messenger" in glioma cells connecting growth factor stimulation with changes in gene transcription.
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PMID:Epidermal growth factor and platelet-derived growth factor induce expression of Egr-1, a zinc finger transcription factor, in human malignant glioma cells. 1153 37

We have evaluated the expression of Kit, a receptor encoded by the c-kit protooncogene, and platelet-derived growth factor-receptors (PDGF-R) alpha and beta in cholangiocarcinoma specimens from 13 separate patients, and provide a case report of a therapeutic trial of imatinib mesylate in one patient. Archived pathologic samples from 13 patients with cholangiocarcinoma were obtained. Tissue sections were hybridized with anti-Kit, anti-PDGF-Ralpha and anti-PDGF-Rbeta monoclonal antibodies. Kit, PDGF-Ralpha and PDGF-Rbeta expression was seen in 31, 69 and 46% of samples, respectively. All patients with PDGF-Rbeta expression also expressed PDGF-Ralpha. Three out of four patients with Kit expression did not express either PDGF receptor and only one patient exhibiting expression of PDGF expressed Kit. Cohen's kappa statistic demonstrated that PDGF and Kit expression were inversely correlated with borderline significance (p=0.052; kappa=-0.4742, 95% confidence interval -0.9821 to 0.03364). In one case, strong Kit expression was noted in a tumor from a metastatic lymph node, but was absent in the primary tumor, suggesting that Kit may be related to invasive or metastatic potential. Given the high level of expression defined in this study, a prospective clinical trial incorporating imatinib mesylate, alone or in combination with cytotoxic chemotherapy, and especially in chemotherapy-naive patients, should be considered for patients with cholangiocarcinoma.
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PMID:Expression of Kit and platelet-derived growth factor receptors alpha and beta in cholangiocarcinoma, and case report of therapy with imatinib mesylate (STI571). 1450 88

Sunitinib (SU-11248, Sutent) inhibits at least eight receptor protein-tyrosine kinases including vascular endothelial growth factor receptors 1-3 (VEGFR1-VEGFR3), platelet-derived growth factor receptors (PDGFRalpha and PDGFRbeta), stem cell factor receptor (Kit), Flt-3, and colony-stimulating factor-1 receptor (CSF-1R). VEGFR1 and VEGFR2 play key roles in vasculogenesis and angiogenesis. PDGFRbeta, which is found in pericytes that surround capillary endothelial cells, plays a pivotal role in stabilizing the vascular endothelium. Sunitinib inhibits angiogenesis by diminishing signaling through VEGFR1, VEGFR2, and PDGFRbeta. Renal cell cancers that have metastasized, or spread from the primary tumor, exhibit extensive vascularity, and sunitinib is approved for the treatment of these neoplasms. Activating Kit mutations occur in about 85% of gastrointestinal stromal tumors and activating PDGFRalpha mutations occur in about 5% of these tumors. Sunitinib is approved for the treatment of those tumors that are resistant to imatinib (STI-571, Gleevec), another Kit and PDGFRalpha protein-tyrosine kinase inhibitor. Both sunitinib and imatinib bind reversibly to the ATP binding site of their target kinases and thereby inhibit their catalytic activity.
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PMID:Sunitinib: a VEGF and PDGF receptor protein kinase and angiogenesis inhibitor. 1736 63

The Forkhead/Fox transcription factor Foxc2 is a critical regulator of vascular development. However, the role of Foxc2 in pathological angiogenesis in cancer remains unknown. Here we show that FoxC2 is highly expressed in human breast and colonic tumors and in the tumor endothelium in human and mouse melanomas. Using the B16 melanoma tumor model, we investigated the function of Foxc2 in tumor angiogenesis. After subcutaneous injection of B16 melanoma cells, primary tumor growth as well as neovascularization was markedly reduced in mice lacking one copy of the Foxc2 gene (Foxc2+/-). Consistently, expression levels of several angiogenic factors, including vascular endothelial growth factor (Vegf), matrix metallopeptidase 2 (Mmp2), and platelet-derived growth factor-B (Pdgfb), were significantly decreased in B16 tumors grown in Foxc2+/- mice, and tumor blood vessels formed in Foxc2+/- mice showed reduced coverage of mural cells and endothelial cell apoptosis. In addition, the tumor tissue in Foxc2+/- mice had an accumulation of necrotic cells. Taken together, these findings demonstrate that haplodeficiency of Foxc2 results in impaired formation of tumor blood vessels as well as reduced tumor growth and thereby provide evidence that Foxc2 is critical for tumor development and angiogenesis.
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PMID:The Foxc2 transcription factor regulates tumor angiogenesis. 2006 Aug 10

Prostate adenocarcinoma is the second leading cause of cancer death among men, due primarily to the fact that the majority of prostate cancers will eventually spread to the skeleton. Metastatic dissemination requires a complex series of coordinated events that result in cells that escape from the primary tumor into the circulation and eventually colonize a distant organ. The ability of these cells to evolve into macroscopic metastases depends strongly on their compatibility with, and ability to utilize, this new microenvironment. We previously showed that bone-metastatic prostate cancer cells exposed to human bone marrow respond by activation of cell survival pathways, such as phosphoinositide 3-kinase/Akt, and that these events are mediated by the alpha-receptor for platelet-derived growth factor (PDGFRalpha). Our studies and others have shown that PDGFRalpha may be activated by mechanisms independent of PDGF ligand binding. Here, we provide conclusive evidence that soluble components of human bone marrow can activate PDGFRalpha through a mechanism that does not require the canonical binding of PDGF ligand(s) to the receptor. In particular, we found that dimerization of PDGFRalpha monomers is not induced by human bone marrow, but this does not prevent receptor phosphorylation and downstream signaling from occurring. To establish the relevance of this phenomenon in vivo, we used a PDGFRalpha mutant lacking the extracellular ligand-binding domain. Our studies show that this truncated PDGFRalpha is able to restore bone-metastatic potential of prostate cancer cells as effectively as the full-length form of the receptor.
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PMID:The alpha-receptor for platelet-derived growth factor confers bone-metastatic potential to prostate cancer cells by ligand- and dimerization-independent mechanisms. 2044 96

The extracellular matrix protein Laminin B1 (LamB1) regulates tumor cell migration and invasion. Carcinoma cells acquire invasive properties by epithelial to mesenchymal transition (EMT), which is a fundamental step in dissemination of metastatic cells from the primary tumor. Recently, we showed that enhanced translation of LamB1 upon EMT of malignant hepatocytes is mediated by an internal ribosome entry site (IRES). We demonstrated that the IRES transacting factor La binds the minimal IRES motif and positively modulates IRES activity of LamB1. Here, we show that platelet-derived growth factor (PDGF) enhances IRES activity of LamB1 by the increasing cytoplasmic localization of La during EMT. Accordingly, cells expressing dominant negative PDGF receptor display reduced cytoplasmic accumulation of La and show no elevation of IRES activity or endogenous LamB1 levels after stimulation with PDGF. Furthermore, La-mediated regulation of LamB1 IRES activity predominantly depends on MAPK/ERK signaling downstream of PDGF. Notably, LamB1 expression is not significantly downregulated by the impairment of the translation initiation factor eIF4E. In vivo, knockdown of La associated with decreased LamB1 expression and reduced tumor growth. Together, these data suggest that PDGF is required for the cytoplasmic accumulation of La that triggers IRES-dependent translation of LamB1 during EMT.
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PMID:PDGF enhances IRES-mediated translation of Laminin B1 by cytoplasmic accumulation of La during epithelial to mesenchymal transition. 2290 67


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