Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This paper reports the effect of vitamin A and its derivatives, the retinoids, on plasminogen activator (PA) synthesis in chick embryo fibroblast cultures (CEF). Low concentrations of retinoic acid (RA) (10(-6)-10(-10) M) and the retinoids stimulated PA synthesis in CEF; the maximal stimulation achieved, 9--10 fold, was somewhat lower than that obtained with optimal concentrations of the potent tumor promoter phorbol myristate acetate (PMA). This action of RA required protein and mRNA synthesis but, in contrast to enzyme induction by PMA and/or sarcoma virus transformation, retinoid effects were not significantly inhibited by elevated concentrations of cAMP. In inducing and/or stimulating PA production, the effects of RA and sarcoma virus transformation were synergistic rather than additive. Analogous synergism was observed between RA and PMA, but only at suboptimal concentrations of the latter. RA did not affect PA production in normal or transformed cultures maximally stimulated by PMA. These findings may help to elucidate the role of retinoids in promoting tumor growth, tissue remodeling and teratogenesis.
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PMID:Plasminogen activator in chick fibroblasts: induction of synthesis by retinoic acid; synergism with viral transformation and phorbol ester. 21 37

Embryonal carcinoma cells, the stem cells of teratocarcinomas, usually undergo extensive differentiation in vivo and in vitro to a wide variety of cell types. There exist, however, several embryonal carcinoma cell lines that have almost completely lost the capacity to differentiate, so that the cells are propagated primarily as the stem cells. Using one such cell line, F9, we have found that retinoic acid at concentrations as low as 10(-9) M induces multiple phenotypic changes in the cultures in vitro. These changes include morphological alteration at the resolution of the light microscope, elevated levels of plasminogen activator production, sensitivity to cyclic AMP compounds and increased synthesis of collagen-like proteins. The nature of these changes, as well as their independence of the continued presence of retinoic acid, are consistent with the proposition that retinoic acid induces differentiation of embryonal carcinoma cells into endoderm.
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PMID:The induction of differentiation in teratocarcinoma stem cells by retinoic acid. 21 38

To explore the generality of the effects of sarcoma viruses, tumor-promoting phorbol esters and retinoic acid, we have studied plasminogen activator production in differentiating chick myogenic cultures. Although slightly higher than in chick fibroblast cultures, the level of spontaneously synthesized enzyme is low; it reaches a peak shortly after maximum cell fusion has been completed and then declines. Rous sarcoma virus (RSV) transformation of differentiating myotubes was accomplished by infecting myoblasts with a temperature-sensitive mutant, maintaining cultures at the nonpermissive temperature until completion of fusion and shifting to permissive temperatures at selected times thereafter. RSV transformation, phorbol myristate acetate (PMA) and retinoic acid all induced high levels of plasminogen activator production by differentiating myotubes in the absence of DNA synthesis. In comparison with fibroblasts, virus-induced enzyme synthesis by myogenic cultures proceeded more slowly but ultimately reached comparably high levels. Whereas cAMP strongly repressed RSV- and PMA-induced plasminogen activator production by chick fibroblasts, it weakly stimulated enzyme synthesis by myotubes. This suggests that enzyme induction by RSV and PMA is not mediated primarily through effects on cAMP metabolism.
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PMID:Plasminogen activator in chick embryo muscle cells: induction of enzyme by RSV, PMA and retinoic acid. 21 22

The regulation of plasminogen activators (PA) and their inhibitors (PAI) in the rat cell lines: HTC and L2 was studied. HTC plasminogen activator inhibitor type 1 (PAI-1) production was stimulated by dexamethasone, serum factors and insulin; that of tissue-type plasminogen activator (tPA) by cAMP raising agents. Retinoic acid, butyrate, phorbol ester and endotoxin did not affect net PA/PAI activity elaborated by HTC. L2 cells produced tPA, which production was stimulated by retinoic acid, phorbol myristate acetate, butyrate and cAMP; serum factors blunted their response, whereas in the synthetic serum substituting medium Ultraculture and with cocktail Ultroser the action of tPA stimulators was enhanced.
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PMID:Regulation of plasminogen activation in rat cell lines. 128 21

From a series of naphthalene and benzoic acid derivatives we have identified synthetic retinoic acid analogues exhibiting high selectivity for the nuclear retinoic acid receptors RAR alpha (Am 580), RAR beta (CD 2019) and RAR gamma (CD 437) as well as ligands sharing high affinities for all RAR subtypes (CD 367). The compounds were evaluated in two complementary screening systems: (1) binding to nuclear proteins extracted from COS-7 cells after transfection with the appropriate expression vectors, and (2) induction of plasminogen activator in the embryonic mouse teratocarcinoma cell line F9. All compounds behaved as retinoic acid agonists in the F9 test.
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PMID:Selective synthetic ligands for human nuclear retinoic acid receptors. 131 57

When F9 teratocarcinoma cells are treated with retinoic acid plus cyclic AMP (RACF9) they differentiate into parietal endoderm. Differentiation is accompanied by the acquisition of substrate adhesion sites and a change in the pattern of gene expression, including the synthesis of tissue-type plasminogen activator (tPA). We demonstrate here that dihydrocytochalasin B (DHCB) treatment of differentiating F9 cells prevents the assembly of a structured actin cytoskeleton and generates a more rounded and stellate cell morphology. This morphological change is accompanied by the accumulation of the usually visceral endoderm-specific marker urokinase-type plasminogen activator (uPA) and an increase in tPA levels in comparison to untreated RACF9 controls. The increase in tPA accumulation is preceded by an increase in tPA mRNA levels. These effects are reversible, with a lag, when DHCB is removed, and PA accumulation can be stimulated within 24 h when differentiated cells are exposed to DHCB. Exposure to the microtubule disrupting agent colchicine has no effect on uPA or tPA accumulation. In addition, antibody directed against the beta 1 integrin subunit can also specifically elicit increased PA production. Thus disturbing the cytoskeleton and cytoskeleton associated substrate adhesions promotes PA accumulation.
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PMID:Disruption of the cytoskeleton-extracellular matrix linkage promotes the accumulation of plasminogen activators in F9 derived parietal endoderm. 133 Jul 91

Several hormones and inducers of intracellular messengers, known to affect plasminogen-activator (PA) production in other systems, were investigated for putative effects on bovine embryos. Day 8 embryos were cultured for 5 days in a humidified atmosphere of 5% CO2 in air at 37 degrees C in media containing different concentrations of progesterone, oestradiol, dexamethasone, retinoic acid, dibutyryl cyclic AMP (dbcAMP) and phorbol myristate acetate (PMA). At intervals of 24 h, the medium was recovered for PA analysis and overall embryonic diameter was measured. While none of the hormones and agents tested affected PA production (P > 0.05), dimethyl sulfoxide, which was used to dissolve PMA, inhibited PA production during the first 72 h of culture (P < 0.05). PA production was affected by duration of culture (P < 0.05). Concentrations of plasminogen activator in the media were low during the first 48 h, had increased after 72 and 96 h in culture, and either remained high or decreased slightly toward the end of the culture period. With the exceptions of dbcAMP and PMA, the hormones tested in this study did not affect embryonic size. Dibutyryl cAMP caused a progressive decrease in embryonic diameter. PMA resulted in embryo death at high concentrations but at lower concentrations it enhanced overall embryonic diameter throughout the time of culture (P < 0.05). These results suggest that cultured bovine embryos produce PA in a fixed, time-dependent manner, independent of exogenous hormonal regulation.
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PMID:Lack of effect of hormones and inducers of intracellular messengers on plasminogen activator production by bovine embryos in vitro. 133 38

Atherosclerosis is probably caused by multiple interacting factors such as disturbed lipid metabolism; endothelial cell damage, leading to platelet aggregation and monocyte invasion with the release of mitogenic factors; and disorders of fibrin balance, leading to persisting fibrin deposits. Deficient fibrinolysis may (1) predispose to fibrin deposition and contribute to the pathogenesis of atherosclerosis and (2) contribute to occlusive thrombus formation on fissured plaque, provoking atherothrombosis. Prospective epidemiologic studies have so far not provided definitive evidence that deficient fibrinolysis constitutes a significant risk factor for the development of atherosclerosis. Two recent findings, however, strongly suggest a contribution: (1) Increased lipoprotein(a) levels that reduce tissue-type plasminogen activator (t-PA)-mediated clot lysis are a clear risk factor for atherosclerosis; and (2) increased plasminogen activator inhibitor-1 (PAI-1) levels in patients with disturbed glucose tolerance predispose to an accelerated development of atherosclerotic disease. However, deficient fibrinolysis constitutes a risk factor for the development of thrombotic complications (acute myocardial infarction) in patients with coronary artery disease. The potential role of deficient fibrinolysis in the pathogenesis of atherosclerosis and of atherothrombosis suggests that drugs normalizing deficient endogenous fibrinolysis by either reducing PAI-1 synthesis or by stimulating endogenous t-PA synthesis may be of clinical value. Although regulation of the gene expression of PAI-1 and t-PA is presently under active investigation, no potent specific and safe agents to downregulate PAI-1 or to upregulate t-PA have as yet been identified. Retinoic acid appears to be a specific inducer of t-PA synthesis in human endothelial cells in culture and may constitute a model for the development of drugs that stimulate endogenous t-PA synthesis.
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PMID:On the role of coagulation and fibrinolysis in atherosclerosis. 134 93

Retinoic acid induces tissue-type plasminogen activator (t-PA) but not plasminogen activator inhibitor-1 (PAI-1) expression in cultured human umbilical vein endothelial cells (HUVEC). To further investigate the relation between the structure of the retinoids and their ability to induce t-PA synthesis in vitro, 11 analogues were studied in HUVEC culture. The retinoid analogues were classified into one of three groups according to their t-PA-inducing potential. Group 1 showed little induction (0.9- to 1.9-fold after 48 h) at concentrations between 10(-8) and 10(-6) M. Group 2, which includes all-trans-retinoic acid, induced t-PA threefold to fivefold at 10(-6) M but had little effect at 10(-8) M (less than threefold). Group 3, which comprises arotinoid acid (RO-13-7410) and RO-13-6307, induced t-PA antigen secretion fivefold at 10(-8) M. The retinoids of groups 2 and 3 had a terminal carboxyl group and alkyl substitution of the lipophylic head of the retinoid skeleton. The group 3 retinoids also contained an aromatic ring. The t-PA-inducing activity of these third-generation retinoids correlates to some extent with other activities, including regression of papilloma, keratinization in vivo, and clonal inhibition of tumor cell lines in vitro. Some of the retinoids caused a small but significant (up to 1.5-fold at 24 h) increase in PAI-1 antigen secretion. The group 3 retinoids appear to be sufficiently potent inducers of t-PA secretion to warrant further investigation in in vivo animal models.
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PMID:Stimulation by retinoids of tissue-type plasminogen activator secretion in cultured human endothelial cells: relations of structure to effect. 138 May 92

Growth of the human breast cancer cell line MCF-7 is known to be inhibited both by antiestrogens such as 4-hydroxytamoxifen (OHTAM) and by retinoic acid (RA). Uncloned MCF-7 cells (UNC) and two cloned sublines, one sensitive to antiestrogens (E-3) and the other resistant to them (RR), were used in this study. Growth of UNC and E-3 was inhibited by either OHTAM (10(-7) M) or RA (10(-6) M), and this inhibition could not be overcome by the simultaneous addition of estradiol. Subline RR, which was originally selected for resistance to tamoxifen, was resistant to both OHTAM and RA as measured by either growth in culture or colony forming ability. RR was resistant to RA at all concentrations tested between 10(-9) M and 10(-6) M. The inhibition of uncloned MCF-7 cells by RA was dose dependent between 10(-9) M and 10(-6) M. Subline E-3, however, exhibited a mixed response to RA. At 10(-9) M and 10(-8) M, growth was stimulated, but at 10(-7) M and 10(-6) M it was inhibited. The level of estrogen receptor was measured in the same experiment by using a whole cell assay. In the uncloned MCF-7 cultures and in both the RR and E-3 sublines the level of estrogen receptor was increased between 50 and 200% by RA. The production of plasminogen activator by MCF-7 cells is stimulated by estrogen. RA had a dual effect on plasminogen activator production. In the absence of estrogen, RA inhibited production below the unstimulated level, but in cells stimulated by estrogen, RA increased plasminogen activator production. The results reported here support possible interactions between the mechanisms by which cells respond to estrogen, antiestrogens, and retinoids.
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PMID:Responses to retinoic acid of tamoxifen-sensitive and -resistant sublines of human breast cancer cell line MCF-7. 142 59


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