Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombomodulin (TM), recognized as an essential vessel wall cofactor of the antithrombotic mechanism, is also expressed by a wide range of tumor cells. Tumor cell lines subcloned from four patients with malignant melanoma displayed a negative correlation between TM expression and cell proliferation in vitro and in vivo. Overexpression of wild-type TM decreased cell proliferation in vitro and tumor growth in vivo. TM mutants with altered protein C activation capacity lead to a similar effect. In contrast, transfection of melanoma cells with mutant TM constructs, in which a portion of the cytoplasmic or lectin domain was deleted, abrogated the antiproliferative effect associated with overexpression of wild-type TM. Experiments performed with either peptide agonists/antagonists of the thrombin receptor, with hirudin, or with inhibitors of thrombin-TM interaction did not alter the growth inhibitory effect of TM overexpression. These data suggest that TM exerts an effect on cell proliferation independent of thrombin and the thrombin receptor, possibly related to the binding of novel ligands to determinants in the lectin domain which might trigger signal transduction pathways dependent on the cytoplasmic domain.
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PMID:Thrombomodulin modulates growth of tumor cells independent of its anticoagulant activity. 952 72

We evaluated the in vivo anti-metastatic activity of recombinant Ancylostoma caninum Anticoagulant Peptide (rAcAP), a potent (Ki = 265 pM) and specific active site inhibitor of human coagulation factor Xa originally isolated from bloodfeeding hookworms. Subcutaneous injection of SCID mice with rAcAP (0.01-0.2 mg/mouse) prior to tail vein injection of LOX human melanoma cells resulted in a dose dependent reduction in pulmonary metastases. In order to elucidate potential mechanisms of rAcAP's anti-metastatic activity, experiments were carried out to identify specific interactions between factor Xa and LOX. Binding of biotinylated factor Xa to LOX monolayers was both specific and saturable (Kd = 15 nM). Competition experiments using antibodies to previously identified factor Xa binding proteins, including factor V/Va, effector cell protease receptor-1, and tissue factor pathway inhibitor failed to implicate any of these molecules as significant binding sites for Factor Xa. Functional prothrombinase activity was also supported by LOX, with a half maximal rate of thrombin generation detected at a factor Xa concentration of 2.4 nM. Additional competition experiments using an excess of either rAcAP or active site blocked factor Xa (EGR-Xa) revealed that most of the total factor Xa binding to LOX is mediated via interaction with the enzyme's active site, predicting that the vast majority of cell-associated factor Xa does not participate directly in thrombin generation. In addition to establishing two distinct mechanisms of factor Xa binding to melanoma, these data raise the possibility that rAcAP's antimetastatic effect in vivo might involve novel non-coagulant pathways, perhaps via inhibition of active-site mediated interactions between factor Xa and tumor cells.
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PMID:Ancylostoma caninum anticoagulant peptide blocks metastasis in vivo and inhibits factor Xa binding to melanoma cells in vitro. 960 44

We investigated the role of platelets in human melanoma cell (line 397) interaction with vascular endothelial cells (ECs) under flow conditions. The ability of the tumour cells to adhere to the EC monolayer was significantly reduced by application of flow at a shear rate of 250 s(-1). A 2.2-fold increase in tumour cell adhesion to ECs under flow was observed upon addition of thrombin receptor agonist peptide (TRAP)-activated platelets but not resting platelets. A similar increase (2.5-fold) in tumour cell adhesion to ECs under flow was observed when the tumour cells were incubated with resting platelets on thrombin-treated ECs. However, thrombin treatment of the ECs alone had no effect on tumour cell adhesion in the absence of platelets. The enhancement of tumour cell adhesion to ECs by TRAP-activated platelets was virtually abolished by blockade of the platelet glycoproteins P-selectin and GPIIb-IIIa by monoclonal antibodies. Blockade of P-selectin also inhibited the direct adhesion of TRAP-activated platelets to ECs, but did not affect the interaction of the tumour cells with platelets immobilized on subendothelial extracellular matrix (ECM). Blockade of GPIIb-IIIa inhibited both platelet-EC and platelet-tumor cell interactions. Our results indicate that tumour cell adhesion to the endothelium under flow is enhanced by platelets under conditions that allow platelet adhesion to ECs. Inhibition studies suggest that activated platelet adhesion to ECs is mediated by P-selectin and GPIIb-IIIA, and tumour cell adhesion to EC-bound platelets--mainly by GPIIb-IIIa.
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PMID:Thrombin promotes platelet-mediated melanoma cell adhesion to endothelial cells under flow conditions: role of platelet glycoproteins P-selectin and GPIIb-IIIA. 964 16

Several studies indicated that activation of the clotting system may promote the growth and the invasive behavior of tumor cells. In the present study, we evaluated the migratory response of various melanoma cell lines to several clotting factors and prothrombin derivatives (thrombin, fragment 1, fragment 2 and kringle 1 fragment). Prothrombin, thrombin and fragment 1 stimulated chemotaxis of the murine (K-1735 M2, X21) and human A375 (SM) melanoma cell lines. Prothrombin and prothrombin fragment 1 showed their maximal chemotactic activity at 0.5 approximately 1 microM. Chemotaxis induced by thrombin was inhibited by hirudin, but not that induced by prothrombin or fragment 1. Other clotting proteins and the fragment 2 and kringle 1 fragment of prothrombin did not elicit chemotactic activity. Checkerboard analysis indicated that motility was directional with a significant chemokinetic component. The K-1735 M2 cells also migrated in a concentration-dependent manner to substratum-bound insoluble prothrombin, thrombin or fragment 1. Ligand binding assays showed that both prothrombin and fragment 1 bound to K-1735 M2 cells with apparent Kds of 0.5 microM. This binding was inhibited by an excess concentration of unlabeled prothrombin and fragment 1 but not by similar concentrations of other prothrombin fragments. These findings suggest that prothrombin and its fragment 1 exert chemotactic activity on melanoma cells by different mechanisms and different binding sites from that induced by thrombin.
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PMID:Prothrombin and its derivatives stimulate motility of melanoma cells. 975 19

Thrombin-treated tumor cells induce a metastatic phenotype in experimental pulmonary murine metastasis. Thrombin binds to a unique protease-activated receptor (PAR-1) that requires N-terminal proteolytic cleavage for activation by its tethered end. A 14-mer thrombin receptor activation peptide (TRAP) of the tethered end induces the same cellular changes as thrombin. Four murine tumor cells (Lewis lung, CT26 colon CA, B16F10 melanoma, and CCL163 fibroblasts) contain PAR-1, as detected by reverse transcriptase-polymerase chain reaction (RT-PCR). B16F10 cells did not contain the two other thrombin receptors, PAR-3 and glycoprotein Ib. TRAP-treated B16F10 tumor cells enhance pulmonary metastasis 41- to 48-fold (n = 17). Thrombin-treated B16F10 cells transfected with full-length murine PAR-1 sense cDNA (S6, S7, S14, and S22) enhanced their adhesion to fibronectin 1.5- to 2.4-fold (n = 5, P <.04), whereas thrombin-treated wild-type cells do not. S6 (adhesion index, 1.5-fold) and S14 (index, 2.4-fold) when examined by RT-PCR and Northern analysis showed minimal expression of PAR-1 for S6 over wild-type and considerable expression for S14. Immunohistochemistry showed greater expression of PAR-1 for S14 compared with wild-type or empty-plasmid transfected cells. In vivo experiments with the thrombin-treated S14 transfectant showed a fivefold to sixfold increase in metastases compared with empty-plasmid transfected thrombin-treated naive cells or S6 cells (n = 20, P =.0001 to .02). Antisense had no effect on thrombin-stimulated tumor mass. Thus, PAR-1 ligation and expression enhances and regulates tumor metastasis.
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PMID:Protease-activated receptor 1 (PAR-1) is required and rate-limiting for thrombin-enhanced experimental pulmonary metastasis. 980 63

Two platelet aggregation inhibitors, ussuristatin 1 (US-1) and 2 (US-2), were newly isolated from the venom of Chinese viper (Agkistrodon ussuriensis) by SP-Toyopearl 650M column chromatography and reverse-phase HPLC. The Mrs of these polypeptides were estimated to be about 8,000 by SDS-PAGE. Analytical gel filtration revealed that US-2 exists as a dimer. Both polypeptides comprised 71 amino acids, whose sequences showed high similarities to those of other disintegrins. US-1 had a typical Arg-Gly-Asp (RGD) sequence, which is responsible for blocking the binding of fibrinogen to the receptor. In US-2, the corresponding sequence was Lys-Gly-Asp (KGD). US-1 strongly suppressed platelet aggregation induced by ADP, collagen, thrombin, and epinephrine with IC50 = 17-33 nM. US-2 also inhibited the platelet aggregation, but the IC50s were about ten times higher. US-1 also dose-dependently inhibited the adhesion of human melanoma cells to fibrinogen and fibronectin, while US-2 did not inhibit the cell adhesion to fibronectin. This indicates that the KGD-bearing disintegrin is a specific inhibitor for the fibrinogen receptor.
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PMID:Ussuristatin 2, a novel KGD-bearing disintegrin from Agkistrodon ussuriensis venom. 988 Jul 93

We have developed novel synthetic peptides that display both antithrombin and disintegrin activity. These peptides were derived from hirutonins, a class of potent proteolytically resistant thrombin inhibitors, in which a dipeptidyl sequence, Asp-Phe or Asp-Ser, was introduced after the proteolytically resistant ketomethylene arginyl glycine isostere. These modified hirutonins inhibited the amidolytic activity of alpha-thrombin (Ki approximately 35 nM), prevented fibrinogen clotting (dTT approximately 100 nM) and inhibited human platelet aggregation and 5-hydroxytryptamine secretion induced by alpha-thrombin (IC50 approximately 600 nM). Unlike their parent hirutonins, they inhibited SFLLR-NH2-induced human platelet aggregation (IC50 approximately 45 microM) without inhibition of 5-HT secretion. These peptides also competed for fibrinogen binding to purified GpIIbIIIa integrin (IC50 approximately microM) and prevented attachment of B16-F10 mouse melanoma cells to vitronectin. We conclude that addition of the dipeptidyl sequence, Asp-Phe or Asp-Ser, in hirutonin molecules confers disintegrin activity. However, this activity was not superior to the activity observed with the linear RGDS peptide and was achieved at the expense of direct antithrombin activity. Additional modifications around the RGD-like adhesion sequence may permit identification of the appropriate conformation for optimal binding to thrombin and to specific integrin receptors.
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PMID:Insertion of the Asp-Ser/Phe sequence in the P' position of hirutonin provides molecules having both antithrombin and disintegrin activity. 1006 72

The coagulation system plays a role in tumor invasion and metastasis. Prothrombin was previously found to stimulate the motility of melanoma cells. We compared the effect of prothrombin and thrombin on cell motility, calcium influx and actin stress filament contraction in highly metastatic osteosarcoma LM8 cells. Prothrombin and thrombin stimulated chemotaxis and chemokinesis of LM8 cells in a dose-dependent manner. Calcium influx was significantly increased after stimulation with thrombin and prothrombin. Thrombin and prothrombin markedly stimulated actin contraction in LM8 cells. Hirudin inhibited the effects of thrombin but not those of prothrombin. Prothrombin appears to stimulate cell locomotion, actin contraction, calcium influx in LM8 cells by different mechanism from thrombin.
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PMID:The zymogen prothrombin stimulates cell locomotion and calcium influx in murine osteosarcoma cells by different mechanism from thrombin. 1056 28

Because thrombin-treated tumor cell-induced metastasis increases tumor nodule volume(12) greater than nodule number, we studied the effect of thrombin on tumor cell growth in vitro and in vivo (murine B16F10 melanoma, human HCT8 colon carcinoma, DU145 prostate carcinoma). Tumor cell growth was measured after 3 to 7 days in 1% fetal calf serum (FCS) + RPMI 1640. We found that, whereas relatively low concentrations of thrombin, 0.1 to 0.5 U/mL (1-5 nmol/L) enhance tumor cell growth in vitro approximately 2- to 3-fold, higher concentrations, 0.5 to 1 U/mL (5-10 nmol/L) impaired cell growth approximately 2- to 4-fold. Impaired cell growth was associated with cell cycle arrest at G(2)M and increased pre-G(o) DNA, as well as apoptosis, measured by tumor cell binding to Annexin V and propidium iodide. Apoptosis was reversed with the general caspase inhibitor, FK-011. The enhancing and inhibiting effects were specific for thrombin (reversed with inactive diisopropyl-fluorophosphate [DFP]-thrombin) and mediated via the protease-activated receptor 1 (PAR-1). PAR-1 activation was demonstrated by (1) use of a cell line, B16F10, devoid of the 3 other thrombin receptors, PAR-3, PAR-4, and GPIb; and (2) greater sensitivity of PAR-1 transfected B16F10 and HCT8 cells to impaired cell growth/apoptosis, 3- and 14-fold, respectively. Thus, thrombin has a bimodal effect on PAR-1 in tumor cells: enhanced growth at low concentration, impaired growth/apoptosis at higher concentration.
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PMID:Concentration-dependent dual effect of thrombin on impaired growth/apoptosis or mitogenesis in tumor cells. 1080 79

Laboratory, histopathological, pharmacological and clinical evidence support the notion that a systemic activation of blood coagulation is often present in cancer patients. On the other hand, epidemiological studies provide evidence of an increased risk of cancer diagnosis following primary thromboembolism. Moreover, the metastatic ability of human breast cancer cells is correlated with the number of thrombin receptors of these cells, and thrombin treatment of B16 melanoma cells dramatically increases the number of lung metastases in rats. We have proposed that these tumour-promoting effects of thrombin can be explained by the ability of thrombin to activate angiogenesis, an essential requirement for tumour progression. Many of the cellular events involved in the angiogenic cascade can be activated by thrombin. At the molecular level, brief exposure of endothelial cells to thrombin causes an upregulation of the receptors (KDR and Flt-1) of VEGF, the key angiogenic mediator. This results in a synergistic effect of thrombin and VEGF in the activation of angiogenesis. In addition, thrombin activates cancer cells to secrete VEGF, thus causing a mutual stimulation between EC and CA cells. Cancer cells exposed to thrombin secrete metalloproteinase 92 KD and overexpress the integrin a(v)b(3), all of which are involved in tumour metastasis.
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PMID:Effects of thrombin/thrombosis in angiogenesis and tumour progression. 1096 95


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