Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

At cellular surfaces, urokinase-type plasminogen activator (uPA) is bound to a specific receptor (uPA-R). When bound to this receptor, uPA activates plasminogen, which is derived from plasma or the interstitial fluids. Thus, plasmin is provided for proteolysis of pericellular proteinaceous substrates. Here we demonstrate by immunocytology and laser scan microscopy that in the human keratinocyte cell line HaCaT uPA-R and uPA are localized together with the integrin alpha v beta 5 in focal contacts. Via the integrin alpha v beta 5, HaCaT cells adhere to vitronectin in a RGD-dependent manner. Plasmin interfered with the alpha v beta 5-mediated keratinocyte adhesion to vitronectin, most likely via cleavage of vitronectin and destruction of its cell binding function. Our findings demonstrate that plasmin, when generated by the uPA-dependent cell surface-associated pathway of plasminogen activation, can abrogate the cell-binding function of vitronectin and can thus disturb the adhesive interaction with this matrix molecule. In focal contacts molecules are assembled that are crucial for adhesion to vitronectin (i.e., the integrin alpha v beta 5), as well as for the generation of plasmin (i.e., uPA-R and uPA), which can negatively influence the binding interaction. We suggest that the plasmin-mediated abrogation of the interaction between the integrin alpha v beta 5 and vitronectin is a pathway of negative regulation; the codistribution of uPA-R/uPA and alpha v beta 5 in focal contacts may restrict this process to areas of cell/matrix contact.
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PMID:Plasmin abrogates alpha v beta 5-mediated adhesion of a human keratinocyte cell line (HaCaT) to vitronectin. 755 34

Since homeobox-containing genes (HOX genes) are a family of transcriptional regulators, which give cells positional information in morphogenesis, cancer metastasis can be explained as a heterotopic expression of HOX genes. In the present study, I transfected HOXD3 gene into human lung cancer A549 cells and investigated alterations of adhesiveness, migration and invasiveness of the tumor cells. Overexpression of the HOXD3 gene enhanced expressions of integrin alpha 3, alpha 4 and beta 3 subunits, and increased adhesive and migratory activities toward fibronectin and vitronectin. It was suggested that the increased migration of the tumor cells resulted from enhanced expression and activation of integrin alpha v beta 3. Furthermore, the overexpression of HOXD3 increased mRNA expressions of urokinase-type plasminogen activator and transcription factors ets-1 and -2. Most of these molecules, which increased with overexpression of HOXD3, are well-known factors associated with tumor invasion and metastasis. Indeed, HOXD3 transfectants revealed high invasive activity to matrigel, a basement membrane model, compared to their parent cells and control neo-transfectants. These findings suggest that abnormal expression of HOXD3 may enhance tumor invasion and metastasis through increased expressions of metastasis-related genes.
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PMID:[Overexpression of human homeobox gene in lung cancer A549 cells results in enhanced motile and invasive properties]. 1049 51

It has been questioned whether there are receptors for urokinase-type plasminogen activator (uPA) that facilitate plasminogen activation other than the high affinity uPA receptor (uPAR/CD87) since studies of uPAR knockout mice did not support a major role of uPAR in plasminogen activation. uPA also promotes cell adhesion, chemotaxis, and proliferation besides plasminogen activation. These uPA-induced signaling events are not mediated by uPAR, but mediated by unidentified, lower-affinity receptors for the uPA kringle. We found that uPA binds specifically to integrin alpha v beta 3 on CHO cells depleted of uPAR. The binding of uPA to alpha v beta 3 required the uPA kringle domain. The isolated uPA kringle domain binds specifically to purified, recombinant soluble, and cell surface alpha v beta 3, and other integrins (alpha 4 beta 1 and alpha 9 beta 1), and induced migration of CHO cells in an alpha v beta 3-dependent manner. The binding of the uPA kringle to alpha v beta 3 and uPA kringle-induced alpha v beta 3-dependent cell migration were blocked by homologous plasminogen kringles 1-3 or 1-4 (angiostatin), a known integrin antagonist. We studied whether the binding of uPA to integrin alpha v beta 3 through the kringle domain plays a role in plasminogen activation. On CHO cell depleted of uPAR, uPA enhanced plasminogen activation in a kringle and alpha v beta 3-dependent manner. Endothelial cells bound to and migrated on uPA and uPA kringle in an alpha v beta 3-dependent manner. These results suggest that uPA binding to integrins through the kringle domain plays an important role in both plasminogen activation and uPA-induced intracellular signaling. The uPA kringle-integrin interaction may represent a novel therapeutic target for cancer, inflammation, and vascular remodeling.
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PMID:Direct interaction of the kringle domain of urokinase-type plasminogen activator (uPA) and integrin alpha v beta 3 induces signal transduction and enhances plasminogen activation. 1652 82

The serine protease urokinase (uPA) binds to the urokinase receptor (uPAR) through its growth-factor domain (GFD, residues 1-49), affecting cell migration, adhesion and growth. Here, we show that uPA can promote cytoskeletal rearrangements and directional cell migration in a GFD-independent manner, through a new and specific interaction between an internal uPA domain coined ;connecting peptide' (residues 132-158) and cell-surface integrin alpha v beta 5. Remarkably, a peptide corresponding to this region (CPp, residues 135-158) retains the ability to bind to alpha v beta 5, eliciting cytoskeletal rearrangements and directing cell migration at a concentration as low as 1-10 pM. These effects are lost in cells not expressing uPAR, indicating that the uPAR is required for CPp-dependent signaling. Furthermore, the CPp-alpha v beta 5-integrin interaction enhances F-actin-enriched protrusions and cell migration induced by the well-established interaction between the uPAR-binding peptide (GFDp, residues 12-32) of uPA and uPAR. These results provide new insight into the function of uPA, which--through individual domains--can engage two different surface receptors (uPAR and alpha v beta 5 integrin), thus initiating and potentiating intracellular signaling and migration.
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PMID:Activation of urokinase receptor by a novel interaction between the connecting peptide region of urokinase and alpha v beta 5 integrin. 1688 93

Cancer-associated or reactive stromal cells are composed of endothelial and inflammatory cells as well as of spindle cells such as fibroblasts and myofibroblasts. In addition to participating to the tumor tissue frame, these cells contribute actively to tumor nutrition and progression through neo-angiogenesis and production of a variety of molecules including numerous proteases, of which a number (MMP14, MMP11, FAP and uPA) are almost exclusively produced by reactive stromal cells. Cancer cells interact with reactive stromal cells which involves a large number of proteases. Several molecules (TGFbeta, PDGF, EMMPRIN) produced by cancer cells induce the production of stromal proteases which in turn stimulate cancer cells through binding to a receptor (for example, MMP-2 and integrin alpha v beta 3). Our experience shows that protease overexpression by reactive stromal cells (cathepsin D, MMP-11, MMP-14) leads to an adverse clinical course in breast cancer. Phenotypic and genotypic differences were found between reactive stromal cells and fibroblasts of normal tissue and our research team found that reactive stromal cells also respond differently to similar stimulations in different individuals. These results support the hypothesis that the biologic behaviour of cancer is not only dependent on tumour characteristics but also on those of patients'stromal cells and that comparable tumours in two individuals may follow different clinical courses. These studies and our experience underscores the importance of characterising cancer-associated reactive stromal cells because of the therapeutic potential of this approach. Furthermore, reactive stromal cells should be genetically more stable that cancer cells and, in theory, should less likely develop mutations and treatment resistance.
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PMID:[Proteases by reactive stromal cells in cancer: an attractive therapeutic target]. 1698 Feb 37