Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0677930 (primary tumor)
 20,210 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to evaluate the relationship of plasminogen activator (PA) activity to the expression of estrogen (ER) and progesterone (PR) receptors, we assayed primary tumor specimens from 121 cases of female breast cancer. Other clinical and histopathological variables were also investigated with respect to their possible association with PA activity in the samples. Statistical correlations were examined by stratified analysis techniques and by multiple regression methods. PA activity was higher in tumors which were ER+PR+ than in those exhibiting other subsets of joint receptor expression, a finding which was particularly predominant in tumors from post-menopausal women. Of the other variables examined, only disease stage, nodal status and vascular infiltration presented marginal positive statistical associations with PA activity, although this was not confirmed by multivariate analysis. The latter technique showed that the presence of PR was sufficient to explain the variation in PA levels. However, ER emerged as the sole significantly explanatory factor when ER+PR- patients were removed from analysis. Both PR and age (negatively) were independent contributory factors for PA activity in the analysis of post-menopausal women. None of the variables examined emerged as being significantly associated with PA when data from pre-menopausal patients were used. These findings indicate that PA activity in breast tumor samples is statistically associated with the expression of functional estradiol receptors, although to a lesser extent than PR.
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PMID:Plasminogen activator expression and steroid hormone receptors in female breast cancer: a multifactorial study. 337 56

In the experimental model system where human tumor cells (HEp3) are implanted on the chorioallantoic membrane (CAM) of the chick embryo, metastasis of HEp3 cells to the embryonic lung occurs within a few days. Such rapidity in tumor dissemination makes this an attractive and potentially useful model for studying the metastatic process. The model, however, involves microvascular trauma at the site of implantation and thus tumor cells may accidentally enter the circulation during implantation or shortly thereafter. If these cells are the cause of the lung metastasis subsequently measured, the model would be in effect a colonization system and not a true, spontaneous metastasis system. The possible contribution of accidental lung colonization to secondary tumor growth was therefore critically examined in this model. In standard metastasis assays, HEp3 was inoculated onto the CAMs of 10-day embryos, which were then incubated for various periods of time. The embryos' lungs were passaged to a second group of CAMs, incubated for 7 days to allow expansion of any HEp3 cells present, and then assayed for HEp3 cells by both microscopy and measurement of human plasminogen activator (PA) activity. Metastasis was evidenced by PA values above background (30 mU/mg protein). Morphological analysis of HEp3 cells in the embryonic lung correlated closely with PA values. To focus on the early stages of tumor dissemination when colonization might occur, the primary tumor was surgically excised from 38 embryos at various intervals after tumor inoculation, and after the operation embryos were allowed to develop to day 17. This procedure increased estimated assay sensitivity down to the level of 1 to 10 cells per lung in embryos operated on within 2 days of inoculation. Median PA values in the transplanted lungs were 13, 3, 37, 1,290 and 3,765 mU/mg protein in the groups operated on at 4 hr, 1, 2, 3 and 4 days after inoculation, respectively. Thus very few or no HEp3 cells arrest and grow in the lungs during the first 24 to 48 hr, but extensive metastasis occurs by 72-96 hr. Accidental colonization therefore plays no major part in the rapid pulmonary spread of HEp3 in this model.
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PMID:Early spontaneous metastasis in the human epidermoid carcinoma HEp3/chick embryo model: contribution of incidental colonization. 374 94

A 6-thioguanine resistant (TGR) variant of the highly tumorigenic and metastatic mammary adenocarcinoma cell line 13762 was obtained. This variant was no longer tumorigenic or metastatic in normal syngeneic rats but did grow as a primary tumor in irradiated animals. Our results suggest that the TGR cell line was rejected by an irradiation-sensitive immunological mechanism. Although the TGR cells produced primary tumors in irradiated animals, there was no evidence of the extensive metastasis seen with the 13762 cells. This apparent inability to metastasize was confirmed by injecting the TGR cells intravenously. Whereas the 13762 cells produced large numbers of metastatic lung foci, there was no evidence of lung metastasis with the TGR cells, even in irradiated animals. Revertant cells for the 6-thioguanine-resistant phenotype were still non-tumorigenic and non-metastatic in normal rats, suggesting that 6-thioguanine resistance is not associated with the altered tumorigenic phenotype. From the TGR variant, cell lines were selected with an increased ability to produce tumors in normal rats. Although some of these revertants were capable of producing limited lung metastases in normal animals, extensive metastases were always seen when the cells were injected into irradiated animals. Differences between the 13762 and the TGR variants were also found in their ability to produce plasminogen activator. The TGR cells released far less plasminogen activator in culture than the 13762 cells. This could be a contributing factor in their different metastatic potentials.
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PMID:A 6-thioguanine-resistant variant of the 13762 cell line which is no longer tumorigenic or metastatic. 689 75

Dissemination of tumor cells includes several steps, such as: (a) detachment of tumor cells from the primary tumor, (b) traversement of the basement membrane, and (c) migration into the extracellular matrix. In these processes, at least two important categories of proteins are involved: proteases and adhesion molecules. In this contribution we describe the expression and function of components of the plasminogen activator (PA) system (proteases) and of integrins (cell-matrix adhesion molecules) in a panel of four human melanoma cell lines with different invasive and metastatic capacity. Regarding the components of the PA system, we found differences in expression of urokinase-type PA (uPA) and type 1 and 2 PA inhibitors (PAI-1 and -2) between metastasizing and nonmetastasizing cell lines. Both components were exclusively expressed in the highly invasive and metastatic cell lines. Interestingly, studies on the expression of PA components in fresh human melanocytic lesions, showed expression of these components exclusively in advanced primary melanomas and melanoma metastases. Regarding integrin expression we found elevated levels of VLA-2 and VLA-6 in the highly invasive and metastatic cell lines compared with normal cultured melanocytes and nonmetastatic melanoma cell lines. In addition, increased adhesion of the highly metastatic cell lines to laminin (LM) and collagen (COLL) was observed. Furthermore, reduced adhesion of normal melanocytes and nonmetastatic melanoma cells to LM and CO was mainly due to the fact that the integrins involved in adhesion to these matrix components were present in an inactive state. Finally, differences were observed in expression of integrins involved in adhesion to fibronectin.
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PMID:Properties of metastasizing and nonmetastasizing human melanoma cells. 759 84

Degradation of the extracellular matrix plays a crucial role in cancer invasion. This degradation is accomplished by the concerted action of several enzyme systems, including generation of the serine protease plasmin by the urokinase pathway of plasminogen activation, different types of collagenases and other metalloproteinases, and other extracellular enzymes. The degradative enzymes are involved also in tissue remodelling under non-malignant conditions, and the main difference appears to be that mechanisms which regulates these processes under normal conditions are defective in cancer. Specific inhibitors have been identified for most of the proteolytic enzymes, e.g. plasminogen activator inhibitors (PAI's) and tissue inhibitors of metalloproteinases (TIMP's). It has been contemplated that these inhibitors counteracted the proteolytic activity of the enzymes, thereby inhibiting extracellular tissue degradation which in turn should prevent tumor cell invasion. This review focuses on plasminogen inhibitor type 1 (PAI-1). It is described that PAI-1 is not produced by the epithelial cancer cell but by the stromal cells in the tumors, suggesting a concerted action between stroma and tumor cells in the processes controlling proteolysis in cancer. The specific localization of PAI-1 to the tumor stroma and in many cases to areas surrounding the tumor vessels has lead us to suggest that PAI-1 serves to protect the tumor stroma from the ongoing uPA-mediated proteolysis. This hypothesis is supported by recent clinical data showing increased levels of PAI-1 in metastases as compared to the primary tumor as well as data demonstrating that high levels of PAI-1 in tumor extracts from breast, lung, gastric and ovarian cancer is associated with a shorter overall survival.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Plasminogen activator inhibitor type 1 in cancer: therapeutic and prognostic implications. 766 68

Proteolytic enzymes are required to mediate tumor cell invasion of adjacent tissues and spread of primary tumors to distant sites. Our objective was to examine the activities and molecular forms of plasminogen activator (PA) and matrix metalloproteases (MP) in primary and secondary growths of SC tumors of three human prostatic cell lines (Du-145, PC-3, and 1-LN-PC-3-1A [1-LN], a subline of PC-3) grown in nude mice. The plasminogen activator activities were 1.7 +/- 1.3 (+/- SD), 6.2 +/- 2.8, and 11.5 +/- 4.2 for Du-145, PC-3, and 1-LN in primary SC tumors, respectively. Urokinase was the predominant molecular form of PA found in each tumor as determined from its molecular size (predominantly 54 kDa with a minor activity of 33 kDa) and sensitivity to amiloride. Prominent MP activities of approximately 68, 76, and 96 kDa as well as lesser activities of about 56, 59, 63, 84, 165, and 180 kDa were found in 1-LN tumors, whereas only less active MP of 59, 68, and 96 kDa were detected in the parental PC-3 cells. Du-145 tumors expressed MP activities of 59 and 96 kDa. Treatment of 1-LN tumor extracts with p-aminophenylmercuric acetate (APMA) significantly reduced the MP activities of 76 and 165 kDa while increasing activities of 56, 59, 65, 68, and 84 kDa. The 76 and 165 kDa MP activities thus appear to be prominent proenzyme forms of MP expressed in the 1-LN tumor. Secondary growths of tumor were subsequently found near the site of initial injection of PC-3 and 1-LN cells following removal of the primary tumor. There was a 42% increase in PA activity in the PC-3 secondary tumors, but only an 8% increase in 1-LN secondary tumors. However, there was no difference in the activities or number of molecular forms of MP in extracts of PC-3 or 1-LN primary or secondary tumors. The substantial expression of MP activities in the more aggressive 1-LN subline of the human prostatic PC-3 cell line indicates that induction of certain MP may be an important regulatory event in prostate tumor progression.
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PMID:Plasminogen activator and metalloprotease activities of Du-145, PC-3, and 1-LN-PC-3-1A human prostate tumors grown in nude mice: correlation with tumor invasive behavior. 795 14

Tumor cell invasion and metastasis is a complex, multistep process that is postulated to require degradation of extracellular matrix at several steps. Urokinase-type plasminogen activator (uPA) is expressed on the cell surface of B16 murine melanoma cells and is thought to contribute to the pericellular proteolysis necessary for tumor cell migration. In vitro modification of B16 melanoma cell surface uPA activity has been shown to alter the invasive and metastatic potential of these murine melanoma cells in vivo. Plasminogen activator inhibitor-1 (PAI-1), a rapid inhibitor of both uPA and tissue-type plasminogen activator (tPA) is the major physiologic regulator of plasminogen activator activity. To test the role of host PAI-1 in the invasive and metastatic capacity of B16 melanoma cells we analyzed local tumor growth and pulmonary metastasis in transgenic mice engineered to overexpress murine PAI-1 in multiple tissues including lung, and in mice completely deficient in PAI-1. No significant difference in the number of pulmonary metastases was observed after intravenous inoculation of tumor cells into PAI-1-overexpressing and PAI-1-deficient mice when compared with wild-type controls. Similarly, in a spontaneous metastasis model, PAI-1-overexpressing and PAI-1-deficient mice demonstrated no difference in primary tumor size or overall survival. These data demonstrate that wide variations of host PAI-1 expression, from complete absence to marked overexpression, does not significantly influence the metastatic potential of B16 melanoma cells in a murine model.
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PMID:Lack of plasminogen activator inhibitor-1 effect in a transgenic mouse model of metastatic melanoma. 863 41

Plasminogen activation has been proposed to play a critical role in cancer invasion and metastasis. The effects of complete ablation of plasminogen activation in cancer was studied by inoculation of a metastatic Lewis lung carcinoma expressing high levels of plasminogen activator into plasminogen-deficient (Plg-/-) mice and matched control mice. Primary tumors developed in all mice with no difference in the rate of appearance between Plg-/- and control mice. However, the primary tumors in Plg-/- mice were smaller and less hemorrhagic and displayed reduced skin ulceration. In addition, dissemination of the tumor to regional lymph nodes was delayed in Plg-/- mice. Surprisingly, no quantitative differences were observed in lung metastasis between Plg-/- and control mice. In addition, Plg deficiency was compatible with metastasis of the primary tumor to a variety of other organs. Nevertheless, Plg-/- mice displayed a moderately increased survival after primary tumor resection. These findings suggest that plasmin-mediated proteolysis contributes to the morbidity and mortality of Lewis lung carcinoma in mice, but sufficient proteolytic activity is generated in Plg-/- mice for efficient tumor development and metastasis.
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PMID:Growth and dissemination of Lewis lung carcinoma in plasminogen-deficient mice. 937 63

Proteases of the plasminogen-plasminogen activator (PA) system play an important role in cancer metastasis. We have examined the expression of these proteases and their cell surface receptors and inhibitors in neuroblastoma, a tumor that originates in cells of the neural crest and is the second most common solid tumor in children. This analysis was performed in seven established human cell lines and 20 primary tumor specimens. Urokinase PA and, in particular, tissue-type PA were expressed in cell lines and in tumor tissues; however, their levels of expression did not correlate with clinical stage. There was little evidence suggesting that neuroblastoma cells concentrate PA activity at their cell surface because urokinase-type PA receptor mRNA was detected in two cell lines and in 5 of 20 tumor samples by reverse transcription-PCR only. PA inhibitor (PAI)-2 was absent in all cell lines and tumor tissue samples examined. However, PAI-1, which was not expressed by the cell lines, was expressed by stromal cells and, specifically, endothelial cells in tumor tissue. By extending the analysis of PAI-1 expression in 64 primary tumor specimens, we found that high PAI-1 expression paradoxically correlated with metastatic stage and tumor recurrence. In vitro experiments indicated that the expression of PAI-1 by human microvascular endothelial cells was stimulated in the presence of SK-N-BE(2) human neuroblastoma cells and neuroblastoma culture medium. Recombinant PAI-1 also promoted SK-N-BE(2) cell detachment from vitronectin and migration from vitronectin toward fibronectin. From these data, we conclude that the up-regulation of PAI-1 expression in endothelial cells may promote rather than inhibit metastasis in neuroblastoma.
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PMID:The plasminogen-plasminogen activator (PA) system in neuroblastoma: role of PA inhibitor-1 in metastasis. 1009 67

Recombinant adenoviral vectors expressing u-PA, t-PA, PAI-1 and PAI-2 were employed to correlate the expression of components of the fibrinolytic system with the invasiveness of HT 1080 tumor cells. Migration through Transwell inserts in vitro in the presence of plasminogen was increased up to 22% by overexpression of u-PA, whereas t-PA had no effect. Gene transfer of PAI-1 or PAI-2 both reduced migration in a dose-dependent manner by up to 43% with PAI-1 and 29% with PAI-2. Two routes of gene transfer were used to alter metastasis of subcutaneously implanted HT 1080 cells expressing firefly luciferase in nude mice. Infection of cultured tumor cells with adenovirus expressing either PAI-1 or PAI-2 before implantation significantly reduced the incidence of lung metastasis by 60% compared with control virus. However, only PAI-2 reduced the incidence of lung and brain metastasis following liver gene transfer. Although PAI gene transfer by either route reduced primary tumor size, it had little effect on tumor vascularization or host survival. The migratory and metastatic phenotype of HT 1080 tumor cells is thus directly dependent on u-PA expression levels and can be altered by gene transfer of u-PA or plasminogen activator inhibitors.
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PMID:Reduction of tumor cell migration and metastasis by adenoviral gene transfer of plasminogen activator inhibitors. 1043 7


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