Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027627 (metastases)
 103,950 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The processes of lymphocyte-endothelial cell interaction and the in vitro assays employed in their study are the subjects of this review. In motility assays in porous filters and gel matrices, it has been shown that lymphocyte migration can be modulated by interleukin-2 (IL-2), IL-3, IL-4, IL-6, and IL-8. Cytokines can also modulate lymphocyte-endothelial adhesion. Endothelial intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) are induced or upregulated by IL-1 or tumor necrosis factor. In addition, interferon-gamma upregulates ICAM-1, and IL-4 can induce VCAM-1. The roles of these cytokines and adhesion molecules in transendothelial migration may be studied in assays in which lymphocytes penetrate layers of cultured endothelial cells. These models can distinguish lymphocyte adhesion from subsequent migration. Using such models, we and others have obtained evidence that both lymphocyte function-associated antigen-1 (LFA-1)/ICAM-1 and very late activation antigen 4 (VLA-4)/VCAM-1 interactions mediate lymphocyte adhesion to endothelial cells, but that LFA-1/ICAM-1 interactions play a greater role in transendothelial migration.
Invasion Metastasis 1992
PMID:In vitro models of lymphocyte transendothelial migration. 138 72

Human carcinomas of the oesophagus, stomach, colorectum, and their liver metastases were previously shown to have increased levels of the urokinase-type plasminogen activator (u-PA). The proteolytic activity of u-PA on the surface of tumour cells is thought to play a key role in invasion and metastasis of malignancies. Therefore, in this study we quantitatively determined the presence of specific u-PA receptors in human gastrointestinal carcinomas, premalignant colonic adenomas, liver metastases, and adjacent normal tissues. All carcinomas showed a 2- to 13-fold higher level of u-PA receptor than their corresponding normal tissues at both the antigen level (ELISA) and the mRNA level (Northern blotting). Colonic adenomas also showed enhanced levels of the u-PA receptor protein. The state of occupancy of the u-PA receptors was determined using a specific ligand-binding assay in which free u-PA receptors were cross-linked with 125I-u-PA and visualized by autoradiography. Colonic carcinomas and liver metastases contained higher levels of free u-PA receptor compared to their corresponding normal tissues. Acid treatment of the receptors prior to cross-linking did not enhance the u-PA/u-PA receptor complex formation. The free u-PA receptor levels in colonic adenomas and in oesophageal and stomach carcinomas showed less difference compared with their normal reference tissues. The increased presence of specific receptors for u-PA in gastrointestinal carcinomas, particularly primary colonic carcinomas and their metastatic lesions in the liver, emphasizes the involvement of the urokinase pathway of plasminogen activation in gastrointestinal carcinogenesis and renders it a putative target for clinical intervention.
Invasion Metastasis 1993
PMID:Increased urokinase receptor levels in human gastrointestinal neoplasia and related liver metastases. 786 Feb 21

In tumour development, proteases such as plasminogen activators (PAs) play a role in degradation of the extracellular matrix and other tissue barriers. Recently, we demonstrated that plasminogen activators, their inhibitors, and urokinase receptor emerge in late stages of cutaneous melanocytic tumour progression. In this study we investigated the expression and distribution of the various components of the PA system and the presence of PA enzyme activity in 45 freshly frozen primary uveal melanoma with known follow-up (14 spindle and 31 non-spindle type) and in metastases (n = 5). Tissue-type PA (t-PA) was found in endothelium of blood vessels and in tumour cells in almost all lesions, and was markedly present at the invasive front (towards the sclera and Bruch's membrane), but no correlation with tumour-related death could be established. Urokinase PA (u-PA) was expressed focally, by only five non-spindle cell melanomas but in all metastases. u-PA expression correlated with occurrence of metastasis. u-PA receptor (u-PAR) was present in one-third of all the tumours examined. Plasminogen activator inhibitors (PAI-1 and PAI-2) were found only focally in approximately 10 per cent of the lesions. Staining of t-PA, u-PA, and PAI was observed in all the metastases. We conclude that in uveal melanoma, u-PA expression may be associated with metastatic disease and accordingly with a poor prognosis. Further research on a larger group of tumours with known follow-up is needed to establish whether u-PA positivity is of additional prognostic value in uveal melanoma.
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PMID:Components of the plasminogen activation system in uveal melanoma--a clinico-pathological study. 789 Dec 28

Degradation of the extracellular matrix and other tissue barriers by proteases like plasminogen activators (PAs) is a prerequisite for neoplastic growth and metastasis. Recently, we reported that highly metastatic behavior of human melanoma cells in nude mice correlates with urokinase-type PA (u-PA) expression and activity and with PA inhibitor type 1 and 2 (PAI-1, PAI-2) expression. Here we report on the occurrence of components of the PA system in the various stages of human melanoma tumor progression in situ. We studied the protein distribution on freshly frozen lesions of common nevocellular nevi (n = 25), dysplastic (= atypical) nevi (n = 16), early primary melanomas (n = 8), advanced primary melanomas (n = 11), and melanoma metastases (n = 17). Tissue-type PA was present in endothelial cells in all lesions, whereas in metastases it could be detected in tumor cells in a minority of the lesions. u-PA, its receptor, PAI-1, and PAI-2 could not be detected in benign and in early stages but appeared frequently in advanced primary melanoma and melanoma metastasis lesions. u-PA was detected in stromal cells and in tumor cells at the invasive front, the u-PA receptor and PAI-2 in tumor cells, and PAI-1 in the extracellular matrix surrounding tumor cells. Localization of the corresponding messenger RNAs and enzyme activities revealed a similar distribution. We conclude that plasminogen activation is a late event in melanoma tumor progression.
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PMID:Plasminogen activators, their inhibitors, and urokinase receptor emerge in late stages of melanocytic tumor progression. 829 13

The plasminogen activator urokinase (u-PA) mediates proteolysis by a variety of human tumor cells. Competitive displacement of u-PA from cellular binding sites results in decreased proteolysis in vitro, suggesting that the cell surface is the preferred site for u-PA-mediated protein degradation. We studied the effect of u-PA receptor blockade on the metastatic capacity of human PC3 prostate carcinoma cells, using transfectants which expressed chloramphenicol acetyl-transferase (CAT). Eight weeks after subcutaneous inoculation of these cells into nude mice, CAT activity was detected in regional lymph nodes, femurs, lungs, and brain, thereby mimicking the organ tropism observed for naturally occurring metastases of prostate cancer. In a second transfection, CAT-expressing PC3 cells received cDNA encoding a mutant u-PA (Ser356-->Ala) which lacks enzymatic activity but which retains full receptor binding affinity. Three mutant u-PA expressors, each with < 5% of wild-type cell-associated u-PA activity, were compared in vivo with independently derived controls. Primary tumor growth was similar in each group of animals and all tumors expressed comparable CAT activity. In contrast, metastasis (as assessed by CAT activity) was markedly inhibited when cell surface u-PA activity was blocked. Levels of CAT activity were reduced by a factor of > 300 in regional lymph nodes, 40-100 in brain tissue, and 10-20 in lung tissue. Metastatic capacity was inhibited similarly when animals were given intermittent intraperitoneal injections of a u-PA/IgG fusion protein capable of displacing u-PA activity from the tumor cell surface. Our results indicate that cell surface u-PA activity is essential to the metastatic process. In addition, the assay system employed in these experiments may be generally useful in testing other therapeutic modalities to limit the spread of primary tumors.
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PMID:Prevention of metastasis by inhibition of the urokinase receptor. 838 64

We have investigated the localization of urokinase-type plasminogen activator (u-PA), type-1 plasminogen-activator inhibitor (PAI-1), u-PA receptor (u-PAR) and alpha(2)-macroglobulin- receptor/low-density-lipoprotein-receptor-related protein (alpha(2)MR/LRP) in human breast tumors by immunohistochemical methods. Frozen sections of 133 primary breast carcinomas, 6 ductal carcinomas in situ and 33 lymph-node metastases were stained with monoclonal antibodies. Formalin-fixed sections of 15 primary tumors and 2 lymph-node metastases were stained with polyclonal antibodies. In primary tumors, u-PA and PAI-1 immunoreactivities were intense in macrophages and mast cells, and moderate in benign and malignant epithelial cells as well as in myofibroblasts and endothelial cells. A sub-group of poorly differentiated tumors showed particularly strong staining of stromal fibroblasts. u-PA immunoreactivity was also present in lymphocytes. alpha(2)MR/LRP and u-PAR immunoreactivities were intense in macrophages, but apart from these cells, alpha(2)MR/LRP was found only in fibroblasts, and u-PAR only in tumor cells located peripherally in tumor-cell clusters and glands and some myofibroblasts in the adjacent stroma. Lymph-node metastases showed staining for u-PA and PAI-1 both of cancer cells and of stromal fibroblasts, also staining for u-PA of lymphocytes. Similarly to some of the poorly differentiated primary tumors, approximately half of the metastases showed very strong staining of stromal fibroblasts, and extracts of these metastases had higher u-PA and PAI-1 levels, as determined by ELISA, than extracts of metastases without this staining pattern. alpha(2)MR/LRP was present only in fibroblasts and u-PAR only in some tumor cells. The presence of u-PA, PAI-1, alpha(2)MR/LRP and u-PAR was controlled biochemically by immunoblotting analyses, ligand-blotting analyses, and direct and reverse zymography. The spatial distribution and the variation in concentration of the various components of the plasminogen-activation system point to a complex, multifunctional role for the 4 proteins in and/or during the development and spread of breast cancer.
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PMID:Immunohistochemical localization of urokinase-type plasminogen activator, type-1 plasminogen-activator inhibitor, urokinase receptor and alpha(2)-macroglobulin receptor in human breast carcinomas. 863 58

In order to invade and spread cancer cells must degrade extracellular matrix proteins. This degradation is catalysed by the concerted action of several enzymes, including the serine protease plasmin. Several experimental studies have shown that inhibition of plasmin formation reduces cancer cell invasion and metastasis, indicating a critical role of this proteolytic pathway in these processes. In order to further study the role of plasmin in cancer progression, we have characterized urokinase-type plasminogen activator (uPA) mediated plasmin formation in three human breast cancer cell lines. Using monoclonal antibodies against uPA and its receptor uPAR, we have investigated the contribution of uPA and uPAR to invasive capacity in an in vitro invasion assay. MDA-MB-231 BAG cells were found to express high protein levels of uPA, uPAR and PAI-1. MDA-MB 435 BAG cells produced low amounts of uPA, PAI-1 and moderate amounts of uPAR, whereas MCF-7 BAG cells showed low levels of uPA, uPAR and PAI-1 protein. In a plasmin generation assay MDA-MB-231 BAG cells were highly active in mediating plasmin formation, which could be abolished by adding either an anticatalytic monoclonal antibody to uPA (clone 5) or an anti-uPAR monoclonal antibody (clone R3), which blocks binding of uPA to uPAR. The two other cell lines lacked the capacity to mediate plasmin formation. In the Matrigel invasion assay the cells showed activity in this order: MCF-7 BAG < MDA-MB-435 BAG < MDA-MB-231 BAG. Testing MDA-MB-231 BAG cells in the Matrigel invasion assay revealed that invasion could be inhibited in a dose-dependent manner either by the clone 5 uPA antibody or by the clone R3 uPAR antibody, suggesting that the cell surface uPA system is actively involved in this invasive process. It is concluded that these three cell lines constitute a valuable model system for in vitro studies of the role of cell surface uPA in cancer cell invasion and has application in the search for novel compounds which inhibit mechanisms involved in uPA-mediated plasmin generation on cancer cells.
Clin Exp Metastasis 1996 May
PMID:Urokinase-type plasminogen activation in three human breast cancer cell lines correlates with their in vitro invasiveness. 867 84

The urokinase-type plasminogen activator (uPA) is considered to play a key role in the process of invasion and metastasis. In several independent studies, in a variety of cancer types (e.g. of the breast, colon, stomach, lung, ovary), high antigen levels of uPA in tumour extracts have been associated with rapid disease progression. In these studies, different sets of antibodies and standards (often as commercially available uPA ELISA kits) have been used. The standards provided with the different uPA ELISA kits are different from each other in both composition and source. In addition, the different uPA ELISA kits use antibodies which differ in specificity and affinity for the various forms of uPA including pro-uPA, HMW-uPA, LMW-uPA, the aminoterminal fragment (ATF) and complexes with inhibitors (PAI-1 and PAI-2) and the receptor (uPAR). Further, the composition of tumour tissue extraction buffers differ significantly among the published studies. Thus, it is not surprising that the ranges of cytosolic uPA levels reported differ considerably even when measured within the same tumour type. These discrepancies led the EORTC Receptor and Biomarker Study Group, in conjunction with the BIOMED-1 consortium on 'Clinical Relevance of Proteases in Tumour Invasion and Metastasis', to organise a workshop to study the characteristics associated with six different uPA immunoassays (ELISA) used in clinical studies reported in the literature. Although the absolute uPA antigen values measured with the respective uPA ELISA kits differed, high correlations were obtained for any two of the four uPA ELISA kits finally applied to sets of breast cancer cytosol preparations. The preparations used at present as standards in the various uPA ELISA kits are not representative of actual human breast cancer cytosols. Thus absolute standardisation is only possible by using a common reference sample (breast cancer cytosol) and similarly composed ELISA uPA kits. Then it will be possible to generate comparable data on clinical tissue as well as to check for batch-to-batch variations within particular ELISA kits.
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PMID:Immunoassays (ELISA) of urokinase-type plasminogen activator (uPA): report of an EORTC/BIOMED-1 workshop. 886 2

Considerable evidence links urokinase plasminogen activator (uPA) bound to its surface receptor (uPAR) with enhanced invasiveness of cancer cells. By blocking uPAR expression in human epidermoid carcinoma cells (HEp3), we have now identified an additional and novel in vivo function for this receptor by showing that receptor-deficient cells enter a state of dormancy reminiscent of that observed in human cancer metastasis. Its main characteristic is survival without signs of progressive growth. Five clones transfected with a vector expressing uPAR antisense RNA under the beta-actin promoter were isolated and shown to have uPAR (at the mRNA and protein levels) reduced by 50 to 80%; four clones, transfected with vector alone and having uPAR levels similar to those of parental cells, served as controls. In confirmation of our previous results, reduced uPAR always coincided with a significantly reduced invasiveness. Each of the control clones produced rapidly growing, highly metastatic tumors within 2 wk of inoculation on chorioallantoic membranes (CAMs) of chick embryos. In contrast, each of the clones with low surface uPAR, whose proliferation rate in culture was indistinguishable from controls, remained dormant for up to 5 mo when inoculated on CAMs. Thus, the reduction in uPAR altered the phenotype of HEp3 tumor cells from tumorigenic to dormant. Although protracted, tumor dormancy was not permanent since in spite of maintaining low uPAR levels, each of the in vivo-passaged antisense clones eventually reemerged from dormancy to initiate progressive growth and to form metastases at a level of 20 to 90% of that of fully malignant control. This observation suggested that other factors, whose expression is dependent on cumulative and prolonged in vivo effects, can compensate for the lack of a full complement of surface uPAR required for the expression of malignant properties. These "reemerged," uPAR-deficient clones were easily distinguishable from the vector-transfected controls by the fact that after only 1 wk in culture, the invasion of CAM by all five clones and tumorigenicity of four of the five clones were reduced back to the values observed before in vivo maintenance. In contrast, dissociated and in vitro-grown cells of control tumors were fully invasive and produced large, metastatic tumors when reinoculated on CAMs. Quantitation of the percent of apoptotic and S-phase cells in vivo, in the control and uPAR-deficient, dormant clones, showed that the mechanism responsible for the dormancy was a diminished proliferation.
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PMID:Reduction in surface urokinase receptor forces malignant cells into a protracted state of dormancy. 915 80

Numerous studies have demonstrated the importance of urokinase plasminogen activator (uPA) and its receptor, uPAR, in the processes of tumor progression and metastasis. Thus, the uPA/uPAR interaction may represent an important target for inhibiting metastatic disease. The baculovirus expression system was used to produce high levels of a secreted uPA-Immunoglobulin G fusion protein (uPA-IgG) which could then be used for displacing uPA from the surface of tumor cells. The recombinant uPA-IgG fusion protein was placed under the control of either the viral polyhedrin promoter or a copy of the viral basic protein promoter. Recombinant viruses were then used to infect Sf9 and BTI-Tn-5B1-4 cells. Infection of both cell types resulted in the production of secreted uPA-IgG. The molecular mass of the secreted protein as determined by SDS-PAGE was approximately 40 kDa. The highest level of secreted uPA-IgG, 444 microg/ml, was found in the culture medium of BTI-Tn-5B1-4 cells 72 h post-infection with the basic protein promoter-uPA-IgG virus. In the case of Sf9 cells, the highest level of secreted protein was 195 microg/ml. The amount of cell-associated uPA-IgG in infected BTI-Tn-5B1-4 cells was significantly less than that of infected Sf9 cells, reflecting the superior secretory capability of the BTI-Tn-5B1-4 cells. The uPA-IgG was readily purified using a combination of zinc chelate and sephacryl S-100 column chromatography. Routinely, greater than 100 mg of greater than 95% pure protein could be obtained per liter of culture medium collected at 72 h post-infection of BTI-Tn-5B1-4 cells with the basic protein promoter virus. BIAcore analysis and competition binding assays using LOX human malignant melanoma cells expressing uPAR indicated that the purified recombinant protein possessed similar ligand binding characteristics to that of human uPA.
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PMID:Production of a urokinase plasminogen activator-IgG fusion protein (uPA-IgG) in the baculovirus expression system. 918 59


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