Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1519670 (tumor angiogenesis)
 6,052 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha) stimulated cell migration, chemotaxis, and the expression of tissue-type plasminogen activator (t-PA) in human omental microvascular endothelial (HOME) cells. Hepatocyte growth factor (HGF) stimulated cell proliferation, but had a negligible stimulatory effect on cell migration, the expression of t-PA and tube-like formation into collagen gel in HOME cells. Basic fibroblast growth factor stimulated cell proliferation, cell migration, tubulogenesis and the expression of urokinase-type plasminogen activator (u-PA) in bovine aortic endothelial (BAE) cells. HOME and BAE cells had both high- and low-affinity receptors for HGF. In BAE cells, u-PA activity and tube-like structures in collagen gel were induced in the presence of HGF alone. In contrast, in HOME cells, t-PA activity and tube-like structures were induced in the presence of TGF-alpha alone, but not in the presence of HGF alone. However, we observed a marked induction of tube formation by HOME cells when both t-PA and HGF were added simultaneously. In the model system for tumor angiogenesis, when HOME cells were co-cultured with a renal cancer cell line, KPK13, tube-like structures were induced in the presence of HGF:KPK13 cells expressed large amounts of t-PA mRNA. Our present study suggested that HGF in concert with active t-PA could be angiogenic in HOME cells.
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PMID:Cooperative roles of hepatocyte growth factor and plasminogen activator in tubular morphogenesis by human microvascular endothelial cells. 750 7

A growing body of evidence has recently implicated TSP and TGF-beta in the process of malignancy, such as tumor cell proliferation, tumor angiogenesis, and metastasis. The purpose of the present study was to evaluate potential mechanisms of TSP and TGF-beta in tumor cell attachment and invasion. Our results indicate that both TSP and TGF-beta promoted tumor cell attachment and spreading in the presence of plasminogen. The mechanism for these effects appeared to be due, in part, to the capacity of TSP and TGF-beta to induce tumor cell production of (PAI-1). PAI-1, which is a natural inhibitor of tumor-cell associated urokinase-type plasminogen activator (uPA) activity, inhibited activation of plasminogen to plasmin in the growth media, thereby preventing plasmin-induced detachment of cells. The TSP-promoted production of PAI-1 could be inhibited not only by anti-TSP antibodies but also by a neutralizing antibody against TGF-beta. These results suggest that TSP by a mechanism involving TGF-beta can promote cell adhesion through stimulation of tumor cell secretion of PAI-1. These data provide evidence that TSP not only has the capacity of functioning as a matrix protein to directly promote cell-substratum adhesion but that TSP can also stimulate cell adhesion and spreading by modulating cell surface protease expression through stimulation of tumor-associated production of PAI-1.
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PMID:Thrombospondin (TSP) and transforming growth factor beta 1 (TGF-beta) promote human A549 lung carcinoma cell plasminogen activator inhibitor type 1 (PAI-1) production and stimulate tumor cell attachment in vitro. 809 68

The urokinase pathway of plasminogen activation is supposed to be involved in proteolytic degradation of the extracellular matrix during cancer invasion. The prognostic value of urokinase-type plasminogen activator (uPA) and type 1 plasminogen activator inhibitor (PAI-1) levels in cytosolic extracts of ductal breast carcinomas was studied, retrospectively, in 118 premenopausal and 72 postmenopausal high-risk patients entered into the protocol of Danish Breast Cancer Cooperative Group trials for adjuvant treatment of breast cancer. The median observation time was 8.5 years. uPA and PAI-1 levels were determined by sandwich enzyme-linked immunosorbent assays. There is a strong correlation between these levels (P < 0.001; r = 0.57). Univariate analysis showed that a high uPA level is significantly associated with short overall survival in both premenopausal (P < 0.001) and postmenopausal (P = 0.03) patients, while a high PAI-1 content significantly predicts shorter overall survival in premenopausal (P = 0.005) and postmenopausal (P < 0.001) patients and shorter relapse-free survival in postmenopausal patients (P < 0.001). When the levels of uPA and PAI-1 are related to those of other prognostic parameters, both high uPA and high PAI-1 levels are associated with grade of anaplasia in premenopausal patients and with number of tumor-positive lymph nodes in postmenopausal patients. A high PAI-1 level is associated with low estrogen and progesterone receptor levels in both pre- and postmenopausal patients. The prognostic value of uPA and PAI-1 levels was compared with that of established prognostic parameters by multivariate analysis. In premenopausal patients, high uPA is an independent prognostic parameter for shorter overall survival, the relative risk being 2.0 (95% confidence interval, 1.1-3.7). In postmenopausal patients, a high PAI-1 level is a strong and independent factor in predicting shorter overall survival with a relative risk of 2.9 (95% confidence interval, 1.5-5.8). In this group of patients a high PAI-1 level is also an independent predictor of shorter relapse-free survival (relative risk, 2.1; 95% confidence interval, 1.1-3.9). These data together with previous reports indicate that uPA and PAI-1 are potentially important prognostic factors in breast cancer. This is in good agreement with the supposed function of uPA in cancer invasion. It is proposed that PAI-1 plays a role in protecting the tumor against degrading itself. Alternatively, the PAI-1 level may be a biochemical marker of tumor angiogenesis.
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PMID:High levels of urokinase-type plasminogen activator and its inhibitor PAI-1 in cytosolic extracts of breast carcinomas are associated with poor prognosis. 838 17

At present the most used method to quantify tumor angiogenesis in human solid tumors is the count of intratumoral microvessels in the primary lesion. This method requires the use of specific markers to vascular endothelium and of immunohistochemical procedures to visualize microvessels. Several studies have found that intratumoral microvessel density (IMD) determined in the primary tumor is significantly associated with metastasis and prognosis in some solid neoplasia, particularly in operable breast carcinoma. The subjective evaluation of IMD made by two observers at the microscope is rapid and of low cost, but presents some difficulties, mainly the identification of the most vascularized area ("hot-spot") within each tumor. This method can be improved upon to attain a better reproducibility among different pathologists. For example, the use of a multiparametric computerized image analysis system (CIAS) seems to be a promising tool to improve accuracy, feasibility and reproducibility of microvessel counts, although there are still some open technical problems to completely automate its use. Angiogenic activity is the result of a balance between angiogenic stimuli and angio-inhibition. Therefore the determination of angiogenic peptides and/or natural angiogenesis inhibitors in the tumor tissue, serum, or urine of cancer patients seems to be a promising alternative to microvessel counting. At present it is possible to determine the expression of basic fibroblast growth factor (bFGF), vascular endothelial growth factor, and transforming growth factor beta using immunohistochemical methods. Serum and urine levels of bFGF can be assessed using an immunoenzymatic assay. Methods used to assess the expression and levels of urokinase-type plasminogen activator (uPA) or plasminogen activator inhibitor-1 (PAI-1) have also been developed, and correlate with angiogenic activity and prognosis of patients with breast cancer. Finally, some investigational methods to assess angiogenesis in vivo are presented and discussed. Angiogenesis is a very complex phenomenon. Thus it seems reasonable to hypothesize that its assessment by using concurrently several of the available methods may provide more valid, accurate, and comprehensive information on the angiogenic activity of each single tumor. For a reliable and reproducible assessment of angiogenesis for all of the assays, validation procedures and quality control protocols are mandatory.
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PMID:Novel methods for the determination of the angiogenic activity of human tumors. 853 66

Binding of the serine protease urokinase (u-PA) to its receptor on tumor cell surfaces facilitates proteolysis and tumor invasion. We undertook this study to determine whether the role of u-PA in prostate cancer induced angiogenesis and secondary tumor growth by developing a homologous, immunocompetent in vivo model in which the tumors cells secrete an inhibitor of the murine u-PA receptor. A mutant recombinant murine u-PA that retains receptor binding but not proteolytic activity was made by PCR mutagenesis. Mutant u-PA and a reporter gene pRK luciferase were transfected and stably expressed in the highly metastatic rat Dunning MAT-LyLu prostate cancer cell line. Several clones expressing mutant u-PA and luciferase were identified by Western blotting, plasminogen zymography, and reverse transcription-PCR. One of these clones, 5C4, was injected s.c. into Copenhagen rats. Compared to animals injected with clones expressing pRK luciferase alone, tumors in animals injected with 5C4 cells were significantly smaller. Moreover, there were fewer lung micrometastases in the 5C4 animals. Primary tumor angiogenesis was measured by microvessel quantification of tissue stained with antibodies against von Willebrand factor. Mean microvessel density in 5C4 tumors was 4.3-fold lower than that in animals with tumors derived from the control tumor cell line (P < 0.0001). Significant inhibition of tumor growth was also observed for two additional MAT-LyLu cell lines expressing mutant u-PA. These findings suggest that cell surface u-PA contributes to prostate cancer growth by enhancing angiogenesis.
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PMID:Inhibition of prostate cancer neovascularization and growth by urokinase-plasminogen activator receptor blockade. 927 33

Recent studies have shown that urokinase (uPA) is an independent prognostic marker in breast cancer. uPA plays a key role in the degradation of tumor matrix and promotes tumor progression. Macrophage expression of uPA appears to be important in this context. Our objective in the present study was to provide evidence that tumor growth factor-beta (TGF-beta) released from breast cancer cells markedly up-regulates uPA expression in tumor-associated macrophages (TAMs). TAMs from 32 breast carcinomas were cultured. Blood monocytes from healthy donors and breast cancer patients as well as tissue macrophages from patients with fibrocystic changes of the breast were also examined. After TGF-beta incubation, uPA levels were tested by ELISA, and uPA mRNA levels were determined by Northern blot analysis. TGF-beta receptor and uPA cell surface fluorescence intensities were determined by flow cytometry; TGF-beta receptors were determined by Western blot analysis. Protein kinase-C dependence was also examined, and immunohistochemical stainings for uPA and TGF-beta were performed. We have demonstrated that TGF-beta markedly up-regulates basal uPA expression (mRNA and protein) in TAMs but only modestly increases uPA production in blood monocytes and tissue macrophages. Exposure of macrophages to TGF-beta1 led to a rapid and sustained increase in uPA mRNA levels, which was independent of de novo protein synthesis and completely inhibited by actinomycin D. H7 markedly reduced the ability of TGF-beta to stimulate uPA expression. Likewise, okadaic acid potentiated the ability of TGF-beta to up-regulate macrophage uPA expression. We suggest that TAMs are more responsive to TGF-beta stimulation than are blood monocytes and tissue macrophages because of different TGF-beta receptor densities. TGF-beta stimulates transcription of the uPA gene, increases uPA-mRNA stability, and activates uPA expression via protein kinase-C-dependent mechanisms. The ability of TGF-beta to induce macrophage uPA expression may provide an indirect mechanism by which this growth factor stimulates angiogenesis. It may be, therefore, that TAMs promote tumor progression and tumor angiogenesis.
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PMID:Transforming growth factor-beta stimulates urokinase expression in tumor-associated macrophages of the breast. 946 Nov 22

We hypothesize that tumor angiogenesis can be limited by the reduction of enzymatic activity of the urokinase type plasminogen activator. The proposed mechanism is elimination of proteolytic activity by the advancing tip of capillaries which utilize proteolysis to produce space needed for vessel expansion. To test our hypothesis, we have investigated the angiostatic activity of synthetic low molecular weight inhibitors of urokinase: amiloride, benzamidine, EGCG, B428, and B623 using the chicken embryo corioallantoic membrane (CAM) model. We found that all tested inhibitors of urokinase cause a significant reduction of angiogenesis.
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PMID:Angiostatic activity of synthetic inhibitors of urokinase type plasminogen activator. 1020 85

The diuretic amiloride has been reported to inhibit both Na+-H+ antiport and the urokinase-type plasminogen activator. As a consequence of these inhibitions, neovascularization may also be inhibited. We hypothesized that if amiloride could be effectively delivered in a site-specific manner, a system might be developed that could inhibit localized angiogenesis. In order to evaluate this possibility we conducted a study that compared two different controlled-release systems into which amiloride had been incorporated. The effectiveness of amiloride release from each delivery system was determined by quantitating angiogenic patterns in a chick chorioallantoic membrane (CAM) system using a fractal analysis software program. The two delivery systems compared were sucrose acetate isobutyrate (SAIB) and calcium alginate. Initial HPLC laboratory tests confirmed that amiloride could be released from both SAIB and calcium alginate in vitro in a sustained manner for 72 h. The CAM studies confirmed that neither SAIB nor calcium alginate alone promoted or inhibited angiogenesis when compared to nontreated controls. The release of amiloride from each delivery vehicle resulted in a significant (P < 0.05) inhibition of angiogenesis following both 24 and 48 h of release compared to controls. There was no difference in inhibition of angiogenesis, however, when comparing SAIB + amiloride treated CAMs with calcium alginate + amiloride treated CAMs. These data suggest that both SAIB and calcium alginate may be useful delivery vehicles for the localized application of amiloride to control angiogenesis. Such a system could potentially control tumor angiogenesis without systemic effects.
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PMID:A comparison of two controlled-release delivery systems for the delivery of amiloride to control angiogenesis. 1038 98

The plasminogen (Plg)/plasminogen activator (PA) system plays a key role in cancer progression, presumably via mediating extracellular matrix degradation and tumor cell migration. Consequently, urokinase-type PA (uPA)/plasmin antagonists are currently being developed for suppression of tumor growth and angiogenesis. Paradoxically, however, high levels of PA inhibitor 1 (PAI-1) are predictive of a poor prognosis for survival of patients with cancer. We demonstrated previously that PAI-1 promoted tumor angiogenesis, but by an unresolved mechanism. We anticipated that PAI-1 facilitated endothelial cell migration via its known interaction with vitronectin (VN) and integrins. However, using adenoviral gene transfer of PAI-1 mutants, we observed that PAI-1 promoted tumor angiogenesis, not by interacting with VN, but rather by inhibiting proteolytic activity, suggesting that excessive plasmin proteolysis prevents assembly of tumor vessels. Single deficiency of uPA, tissue-type PA (tPA), uPA receptor, or VN, as well as combined deficiencies of uPA and tPA did not impair tumor angiogenesis, whereas lack of Plg reduced it. Overall, these data indicate that plasmin proteolysis, even though essential, must be tightly controlled during tumor angiogenesis, probably to allow vessel stabilization and maturation. These data provide insights into the clinical paradox whereby PAI-1 promotes tumor progression and warrant against the uncontrolled use of uPA/plasmin antagonists as tumor angiogenesis inhibitors.
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PMID:The plasminogen activator inhibitor PAI-1 controls in vivo tumor vascularization by interaction with proteases, not vitronectin. Implications for antiangiogenic strategies. 1126 68

Tumor angiogenesis progresses by a dynamic balance between tumor vascular regression and growth. Angiopoietin (Ang)-2 (the natural antagonist for the angiogenic Tie-2 receptor) and vascular endothelial growth factor (VEGF) are thought to be critical regulators in this process; therefore, these may play a critical role in cancer aggressiveness. The aim of this study was to clarify the clinical and biological significance of the expression of Ang-2 in human gastric cancers and to investigate the relationship between Ang-2 together with VEGF and the induction of proteases such as matrix metalloproteinases (MMPs) in the process of tumor development. Eighty-five individuals with gastric cancer, who had undergone surgery without preoperative treatment, were studied. A stable transfectant of the human MKN-7 gastric cancer cell lines with an Ang-2 expression vector was used for the experimental study. First, we examined the relationship between the mRNA expression of Angs by Northern blot analysis and clinicopathological features. High Ang-2-expression cases showed more frequent vascular involvement and more advanced stages of disease compared with low Ang-2-expression cases (P < 0.05). With regard to prognosis, the survival time for patients in the high-Ang-2 mRNA group was significantly shorter (P < 0.05). When we examined the localization of Ang-2 in human gastric cancers, immunohistochemical analysis revealed that this protein was expressed predominantly in cancer tissues when compared with normal tissues. Interestingly it was expressed not only in endothelia cells (ECs) but also in cancer cells. Second, Ang-2-transfected cells were implanted in vivo into the gastric walls of nude mice. Ang-2-transfectant mice developed highly metastatic tumors with hypervascularity as compared with MKN-7 or control vector-transfectant tumors. There was a significant correlation between Ang-2 mRNA expression and lower grade of vessel maturation. Third, on the basis of the in vivo data, we focused on production of proteases such as MMPs to investigate possible mechanisms in these processes. MMP-1, MMP-9, and urokinase-type plasminogen activator in ECs were strongly up-regulated by Ang-2 in the presence of VEGF in vitro. These data suggest that production of Ang-2 is implicated in tumor development in human gastric cancers. Its production may contribute to tumor angiogenesis by induction of proteases in ECs, which may be enhanced in the presence of VEGF.
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PMID:Angiopoietin-2 is related to tumor angiogenesis in gastric carcinoma: possible in vivo regulation via induction of proteases. 1128 Jul 79


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