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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This manuscript reviews the molecular aspects of tumor cell invasion of extracellular matrix. The changes in cell:substrate and cell:cell receptors that characterize motile cells are discussed for their importance not only in mediating invasive cell behavior, but also as diagnostic markers for invasive potential. Autocrine motility and scatter factors probably have key roles in initiating migratory behavior, while specific and non-specific extracellular matrix alterations can facilitate cell locomotion. The manuscript reviews reported changes, such as induction of cell motility, matrix degrading enzymes, and invasive/metastatic potential, which can follow transfection with ras oncogenes, and details the key roles of metalloproteinases, heparanase, and plasminogen activator in matrix degradation. Enzymatic inhibitors of initial steps in extracellular matrix degradation, such as rTIMP, and synthetic blockers of adhesive steps in tumor cell invasion represent types of reagent with potential as anti-metastatic agents. Their potential usefulness may be increased if they can be incorporated into a novel, long-term, non-traditional delivery system.
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PMID:Cell-matrix interactions during tumor invasion. 225 11

The effect of plasminogen on the ability of highly metastatic ESb mouse lymphoma cells to degrade heparan sulfate (HS) in the subendothelial extracellular matrix (ECM) was studied. A metabolically sulfate-labeled ECM was incubated with the lymphoma cells, and labeled degradation products were analyzed by gel filtration on Sepharose 6B. Heparanase-mediated release of low-Mr (0.5 less than Kav less than 0.85) HS cleavage products was stimulated fourfold in the presence of plasminogen. Incubation of plasminogen alone with the ECM resulted in its conversion into plasmin, which released high-Mr (Kav less than 0.33) labeled proteoglycans from the ECM. Heating the ECM (80 degrees C, 1 hr) abolished its ability to convert plasminogen into plasmin, yet plasminogen stimulated, through its activation by the ESb plasminogen activator, heparanase-mediated release of low-Mr HS fragments. Heparin inhibited both the basal and plasminogen-stimulated degradation of HS side chains but not the total amount of labeled material released from the ECM. In contrast, aprotinin inhibited the plasminogen-stimulated release of high- as well as low-Mr material. In the absence of plasminogen, degradation of heated ECM by ESb cells was completely inhibited by aprotinin, but there was only a partial inhibition of the degradation of native ECM and no effect on the degradation of soluble HS proteoglycan. These results demonstrate that proteolytic activity and heparanase participate synergistically in the sequential degradation of ECM HS and that the ESb proteolytic activity is crucial for this degradation when the ECM-associated protease is inactivated. Plasminogen may serve as a source for the proteolytic activity that produces a more accessible substrate to the heparanase.
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PMID:Involvement of both heparanase and plasminogen activator in lymphoma cell-mediated degradation of heparan sulfate in the subendothelial extracellular matrix. 242 87

Incubation of plasminogen with the subendothelial extracellular matrix (ECM) synthesized by cultured bovine corneal and aortic endothelial cells resulted in generation of fibrinolytic activity, indicated by proteolysis of 125I-fibrin in a time- and dose-dependent manner. Both tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA) were identified in the ECM by fibrin zymography, immunoblotting, and inhibition of plasminogen activation by anti-u-PA and anti-t-PA antibodies. Most of the ECM-resident plasminogen activator (PA) activity did not originate from intracellular PA release occurring when the endothelial cells were lyzed and the ECM exposed, since a comparable amount of PA was associated with the ECM when the cells were lyzed with Triton X-100 or removed intact by treatment with 2 M urea. Active u-PA and t-PA were released from ECM by treatment with heparanase (endo-beta-D-glucuronidase), indicating that some of the ECM-resident PA activity is sequestered by heparan sulfate side chains. These results indicate that both u-PA and t-PA produced by endothelial cells are firmly sequestered in an active form by the subendothelial ECM. It is suggested that ECM-resident plasminogen activators participate in sequential matrix degradation during cell invasion and tumor metastasis. PA activity may also function in release of ECM-bound growth factors (i.e., basic fibroblast growth factor) and activation of proenzymes (i.e., prothrombin), resulting in modulation of the ECM growth-promoting and thrombogenic properties.
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PMID:Extracellular matrix produced by cultured corneal and aortic endothelial cells contains active tissue-type and urokinase-type plasminogen activators. 843 96

To investigate the role of the transcription factor nuclear factor kappaB (NFkappaB) in tumor metastasis, we generated a murine lung alveolar carcinoma cell line (Line 1) defective in NFkappaB-signaling by retroviral delivery of a dominant negative inhibitor of NFkappaB. The NFkappaB signal blockade resulted in the down-regulation of prometastatic matrix metalloproteinase 9, a urokinase-like plasminogen activator, and heparanase and reciprocal up-regulation of antimetastatic tissue inhibitors of matrix metalloproteinases 1 and 2 and plasminogen activator inhibitor 2. NFkappaB signal blockade did not affect tumor cell proliferation in vitro or in vivo but prevented intravasation of tumor cells in an in vivo chick chorioallantoic membrane model of metastasis as well as spontaneous metastasis in a murine model. These findings suggest that NFkappaB plays a central and specific role in the regulation of tumor metastasis and may be an important therapeutic target for development of antimetastatic cancer treatments.
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PMID:Tumor metastasis and the reciprocal regulation of prometastatic and antimetastatic factors by nuclear factor kappaB. 1111 32

Diabetic nephropathy (DN) is a serious complication in diabetes. Major typical morphological changes are the result of changes in the extracellular matrix (ECM). Thus, basement membranes are thickened and the glomerular mesangial matrix and the tubulointerstitial space are expanded, due to increased amounts of ECM. One important ECM component, the proteoglycans (PGs), shows a more complex pattern of changes in DN. PGs in basement membranes are decreased but increased in the mesangium and the tubulointerstitial space. The amounts and structures of heparan sulfate chains are changed, and such changes affect levels of growth factors regulating cell proliferation and ECM synthesis, with cell attachment affecting endothelial cells and podocytes. Enzymes modulating heparan sulfate structures, such as heparanase and sulfatases, are implicated in DN. Other enzyme classes also modulate ECM proteins and PGs, such as matrix metalloproteinases (MMPs) and serine proteases, such as plasminogen activator, as well as their corresponding inhibitors. The levels of these enzymes and inhibitors are changed in plasma and in the kidneys in DN. Several growth factors, signaling pathways, and hyperglycemia per se affect ECM synthesis and turnover in DN. Whether ECM components can be used as markers for early kidney changes is an important research topic, whereas at present, the clinical use remains to be established.
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PMID:Diabetic nephropathy and extracellular matrix. 2310 23