UNIPROT:P00750 - FACTA Search

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Query: UNIPROT:P00750 (PLA)
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We have expressed human tissue plasminogen activator (t-PA) gene at high levels in a mouse cell line. The t-PA cDNA with deletion of the long 3' untranslated region was inserted into a bovine papilloma virus (BPV) derived vector under the control of a mouse metallothionein promoter. The mouse metallothionein (mMT) gene also provided signals for splicing and polyadenylation. Mouse C127 cells transfected with this construct secreted t-PA at high levels into the cell culture medium. When an SV40 polyadenylation signal was inserted between the t-PA cDNA and the mMT splicing signals, the expression level increased by several fold. The expression levels did not increase further upon either introduction of Rous sarcoma virus LTR into the plasmid or mutation of the translation initiation context sequence to conform with the consensus one. Most of the plasmid appears to be integrated into the host chromosome. Cells producing high levels of t-PA tend to detach from the dish in a few days after passage. When grown on porous microcarriers, however, such cells can be maintained in culture for months and t-PA can be harvested continuously.
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PMID:High level expression of human tissue-type plasminogen activator gene in mouse C127 cell. 136 38

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

A number of hybrid plasminogen activator genes were constructed from the t-PA and u-PA cDNAs and expressed using a bovine papilloma virus vector and mouse C-127 cells. Hybrid A was constructed by replacing the finger (F) and EGF domains of t-PA with the EGF and Ku domains of u-PA, while hybrids B and C had an extra Ku inserted before or after the double kringle (K1-K2) region of t-PA respectively. While all the hybrids showed comparable enzymatic activities towards a small substrate (S-2288), they had different activities in binding to fibrin clots as well in the fibrin-dependent plasminogen activation, the order of activities being: t-PA greater than or equal to hybrid B greater than hybrid C greater than hybrid A. Carbohydrate analysis showed that while hybrid C, like rt-PA, had at least one high-mannose type sugar chain (probably at residue 117 in K1), the other hybrids had only complex-type carbohydrates suggesting that domain interaction in t-PA might influence glycan processing. Pharmacokinetic studies in dog showed that hybrid B had a significantly longer plasma half-life than rt-PA. Thrombolytic efficacies of hybrid B and rt-PA were compared in dog model using an artificially induced coronary thrombus. Complete thrombolysis was achieved with 18 mg and 50 mg dosages for hybrid B and rt-PA respectively. These data show the superior pharmacokinetic and thrombolytic properties of hybrid B compared to rt-PA.
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PMID:Biological properties of hybrid plasminogen activators. 212 69

Human tissue-type plasminogen activator (t-PA) cDNA was cloned from uterine tissue and engineered in expression vectors for production in mouse C127 cells. The vectors consisted of the bovine papilloma virus-1 (BPV-1) genome and t-PA transcriptional unit with a mouse metallothionein (MT-1) promoter at the 5' end and MT-1 genomic sequences or SV40 early introns and polyadenylation signals at the 3' end. Analysis of the expression vectors transfected into cells revealed that t-PA is expressed 100- to 200-fold more with an intronless vector utilizing the SV40 polyadenylation signal than with other, intron-containing vectors. RNA analysis of stable cell lines indicated that t-PA expression levels correlated with mRNA abundance. DNA copy number and transcriptional rate of the MT-1 promoter remained constant in cell lines transformed by different BPV expression vectors. Uterine t-PA produced by recombinant DNA means was enzymatically active and similar in properties to Bowes melanoma t-PA.
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PMID:Expression of human uterine tissue-type plasminogen activator in mouse cells using BPV vectors. 282 47

We have used two kinds of vectors to express a cDNA of human tissue plasminogen activator (t-PA) in mammalian cells. In one case, cDNAs inserted into vectors based on bovine papilloma virus were introduced into cultured murine cells and cell lines were established that efficiently and continuously secrete enzymatically active t-PA into the medium. Second, the t-PA gene was used to replace the sequences of the simian virus (SV40) genome that code for the viral coat proteins. Virus stocks were generated and used to infect a stable line of cultured simian cells. During the resulting lytic infection, expression of the t-PA gene is governed by the potent SV40 late promoter and enzymatically active t-PA accumulates rapidly in the medium. We have used these two vector systems to analyze the biosynthesis and transport of recombinant t-PA and to compare its properties with those of "natural" t-PA secreted by the Bowes line of human melanoma cells. t-PA secreted from all three sources is identical in specific activity (approximately 20,000 units/mg) despite differences in patterns of terminal glycosylation. Furthermore, non-glycosylated t-PA synthesized in the presence of tunicamycin was secreted efficiently and was indistinguishable in specific activity from glycosylated t-PAs.
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PMID:Expression of human tissue-type plasminogen activator from lytic viral vectors and in established cell lines. 303 88

Tissue-type plasminogen activator (t-PA) is a mosaic protein containing several distinct structural domains attached to the serine protease catalytic unit present at its COOH terminus. To investigate structure-function relationships in t-PA, we deleted the NH2-terminal domains, finger and epidermal growth factor, by genetic engineering. The genes for the parent and mutant t-PA were expressed in a bovine papilloma virus-dependent mammalian cell system. The secreted proteins were purified to homogeneity. The mutant protein was processed to the expected size of about 60 kDa compared to approximately 68 kDa for the parent t-PA, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fibrin autography. While the mutant t-PA had amidolytic activity comparable to native t-PA, it did not bind appreciably to fibrin. Consequently, fibrin-dependent enzymic activity, i.e. plasminogen activation in the presence of soluble fibrin and fibrinolysis were lower than with native recombinant t-PA. The effect of deletion of NH2-terminal domains on the plasma half-life (t1/2) was investigated by injecting native and mutant t-PA into mice. While the majority of the t-PA disappeared initially with a t1/2 of about 2 min, mutant t-PA cleared at a much slower rate with t1/2 of about 50 min. These findings suggest that the NH2-terminal domains of t-PA not only determine its specificity for binding to fibrin but also mediate its clearance from plasma in vivo. Furthermore, the catalytic unit in t-PA seems to function autonomously.
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PMID:Structure-function analysis with tissue-type plasminogen activator. Effect of deletion of NH2-terminal domains on its biochemical and biological properties. 312 83

Unlike cell lines transformed with Polyomaviruses, transformants derived by focus formation or colony formation in agarose medium after transfer into rat fibroblast cells (FR3T3 line) of Bovine Papilloma Type 1 (BPV1) DNA were consistently observed to grow poorly in suspension and to remain highly serum dependent for growth in culture. These cells did not produce detectable amounts of plasminogen activator, and kept the flat morphology and organized cytoskeleton characteristic of the normal fibroblast. However, they induced in syngeneic animals the development of tumors with a greater invasive potential than tumors induced by Polyomaviruses. By contrast with the original transformants, cells recovered from the tumors grew efficiently in suspension and produced high levels of plasminogen activator. They still had, however, extended cytoskeletal structures and remained completely dependent on high serum concentrations for growth in culture. The stepwise transformation process induced by BPV1 thus appears strikingly different from that previously observed with polyoma and SV40 viruses. The observed changes in transformation phenotype between transformed line and tumor cells do not correlate with any important modification of the number of autonomous copies of the viral genome, nor with any rearrangement of viral sequences detectable at the level of the blot analysis.
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PMID:The transformed phenotype in culture and tumorigenicity of Fischer rat fibroblast cells (FR3T3) transformed with bovine papilloma virus type 1. 633 Sep 80

The VX2 tumor is derived from a papilloma virus-induced rabbit epithelial cell line. If VX2 tumor cells (trapped in a plasma clot) are introduced intravenously into NZW rabbits, the cells lodge in the lung capillary bed and produce tumors. Independently of the tumor burden (ie, the total tumor weight per rabbit), approximately 15% of rabbits with VX2 lung tumors accumulate an effusion in the interpleural space and this pleural effusion contains products of hemostasis. We hypothesized that these products were of intra-tumoral origin and that they changed in concentration as tumor burden increased. Interrelationships among lung-, tumor-weights, and pleural effusion volumes, and the concentrations of fibrinolytic factors, their catabolic products, and other proteins of pleural effusions were measured in rabbits with a wide range of tumor burdens. Positive correlations between tumor burden and total lung weight and between pleural effusion volume and net lung weight suggested that interstitial fluid from the stroma of tumors passed directly into the extravascular space of the lung(s) and into the interpleural space(s). Analyses of pleural effusions indicated that plasminogen-, alpha(2)-antiplasmin-, and plasminogen activator inhibitor-1-related proteins, urokinase-like- and tissue-plasminogen activator activities, and vascular endothelial growth factor increased in concentration up to a tumor burden of approximately 20-25 g. Plasmin activity and intact fibrinogen were absent. The concentration of fibrin(ogen) degradation products did not change significantly up to a tumor burden of approximately 25 g but increased substantially as tumor burdens exceeded 25 g. In conclusion, interstitial fluid from tumors enters the extravascular space of the host and may accumulate with fluid from non-tumor sources as a pleural effusion. The concentrations of fibrinolytic factors and their products in pleural effusions reflect the tumor burden of the rabbit. Conceivably, the components of a malignant effusion contain much information about the extent of tumor growth.
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PMID:Relationships among tumor burden, tumor size, and the changing concentrations of fibrin degradation products and fibrinolytic factors in the pleural effusions of rabbits with VX2 lung tumors. 1644 2

Matrix metalloproteinases (MMP) play a key role in development of tumor invasion and metestasis. The purpose of the work is the elucidation of peculiarities of expression of MMP-1, MMP-2, MMP-9 and their activity regulators: plasminogen activator uPA and tissue inhibitors of MMPs - TIMP-1 and TIMP-2 in human cell lines of squoamous cell carcinoma (SCC). Comparative study of MMPs' expression was carried out on cell lines SCC which differed in HPV types (HPV-16 and HPV-18): SiHa, Caski - HPV16, Hela, C4-1 - HPV18). As a control, the C33A line was used where HPV copies were absent. The human papilloma viruses (HPV) of high risk--HPV-16, HPV-18, as etiological factors of initiation of cervical cancer, are most widespread and most aggressive among oncogenic HPVs. Study of MMP expression involved estimation of expression of mRNA using the RT-PCR method and determination of collagenolytic activity by hydrolysis of fluorogenic type 1 collagen and also by the zymography method. It was shown that: 1. In both types of cell lines, the MMP-1 expression was essentially increased (2 to 8 times), and in HPV18 lines it was most expressed. The exception was made by the SiHa line in which the decrease of expression of this enzyme was observed. MMP-2 expression was at the control level in both types of cell lines. 2. Expression of inhibitors generally was at the control level. The only exception was the C4-1 line where the expression of TIMP-1 and TIMP-2 was increased in 1,7 and 2,6 times accordingly. Expression of uPA was increased 2 to 4, 5 times in all cell lines except Siha where was lowered to 20%. 3. Collagenolytic activity in the Caski and Hela cell line was 2-3 times higher that it was in control, while the activity in the SiHa cell line was compatible with that in the control. Research of gelatinolytic activity also as well as the data on an expression MPHK has revealed only presence MMFP-2, but not MMP-9 in all cervical carcinoma cell lines. The data obtained provide evidence for a significant disturbance in transformed cells of enzyme/inhibitor/activator ratio--which occurs, for the most part, at the cost of elevated expression of MMP-1 and its activator whereas the expression of MMP-2 and inhibitors remains virtually unchanged, which leads to the increase of the destructive potential of transformed cells.
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PMID:[Matrix metalloproteinases (MMP)--MMP-1,-2,-9 and its endogenous activity regulators in transformed by E7 oncogene HPV16 and HPV18 cervical carcinoma cell lines]. 2447 43

Objective To investigate the difference in texture features on diffusion weighted imaging (DWI) images between breast benign and malignant tumors.Methods Patients including 56 with mass-like breast cancer, 16 with breast fibroadenoma, and 4 with intraductal papilloma of breast treated in the Hainan Hospital of Chinese PLA General Hospital were retrospectively enrolled in this study, and allocated to the benign group (20 patients) and the malignant group (56 patients) according to the post-surgically pathological results. Texture analysis was performed on axial DWI images, and five characteristic parameters including Angular Second Moment (ASM), Contrast, Correlation, Inverse Difference Moment (IDM), and Entropy were calculated. Independent sample t-test and Mann-Whitney U test were performed for intergroup comparison. Regression model was established by using Binary Logistic regression analysis, and receiver operating characteristic curve (ROC) analysis was carried out to evaluate the diagnostic efficiency.Results The texture features ASM, Contrast, Correlation and Entropy showed significant differences between the benign and malignant breast tumor groups (P_ASM=0.014, P_contrast=0.019, P_correlation=0.010, P_entropy=0.007). The area under the ROC curve was 0.685, 0.681, 0.754, and 0.683 respectively for the positive texture variables mentioned above, and that for the combined variables (ASM, Contrast, and Entropy) was 0.802 in the model of Logistic regression. Binary Logistic regression analysis demonstrated that ASM, Contrast and Entropy were considered as the specific imaging variables for the differential diagnosis of breast benign and malignant tumors.Conclusions The texture analysis of DWI may be a simple and effective tool in the differential diagnosis between breast benign and malignant tumors.
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PMID:Value of Magnetic Resonance Imaging Texture Analysis in the Differential Diagnosis of Benign and Malignant Breast Tumors. 3096 78

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