Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein C inhibitor (PCI) is a heparin-dependent serpin present in a native form in plasma at concentrations of 5 micrograms/mL. In vitro, PCI inhibits activated protein C (APC), thrombin, plasma kallikrein (KK) and urokinase-(uPA) and tissue-type plasminogen activator (tPA), and we have shown in vivo inhibition of APC, uPA and KK by PCI. In order to further characterize the physiological role of PCI, we have measured the level of PCI in several biological fluids. PCI antigen was assayed by ELISA and PCI activity was measured by its capability to form complexes with APC in the presence of heparin. Seminal plasma from voluntary donors had PCI levels (160 +/- 20 micrograms/mL, mean +/- SD) about 30 or 40 times higher than those found in blood plasma. Patients under a fertilization program had significantly reduced PCI seminal levels (110 +/- 35 micrograms/mL). Seminal plasma PCI retained about 45% of its activity immediately after ejaculation, and the activity rapidly decreased following incubation of seminal plasma at 37 degrees C, in parallel with the appearance of complexes of PCI with prostate-specific antigen (PSA). PCI was present in seminal vesicle secretion, obtained by autopsy, at concentration similar to that observed in semen, was mostly active and was not inactivated by incubation of secretion at 37 degrees C. The mean functional and antigen levels of PCI in urine from normal donors were 0.58 and 0.25 micrograms/mL, respectively, whereas in saliva these levels were 20 and 0.8 ng/mL, respectively. Amniotic fluid contained PCI antigen levels of 2.1 +/- 0.2 microgram/mL. These results show that PCI is secreted in the seminal vesicles in a functional form, and suggest that PSA, a major secretory component of the prostate, is responsible for its inactivation. They also suggest a physiological role of PCI in reproduction, and show that PCI is present in various biological fluids.
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PMID:Functionally active protein C inhibitor/plasminogen activator inhibitor-3 (PCI/PAI-3) is secreted in seminal vesicles, occurs at high concentrations in human seminal plasma and complexes with prostate-specific antigen. 172 27

The serine protease inhibitor protein C inhibitor is present in semen at a relatively high concentration and forms in vivo complexes with two plasminogen activators also present in semen, urokinase-type and tissue-type plasminogen activators. Therefore, the fact that prostate-specific antigen (PSA), a major prostate enzyme, complexes and inactivates protein C inhibitor (PCI) in semen could have implications in human reproduction. The present study was undertaken to develop an enzyme-linked immunosorbent assay (ELISA) for complexes of PSA with PCI (PSA:PCI) with purified PSA:PCI complexes as a standard. Seminal plasma was utilized as the starting material for purification of complexes by affinity chromatography on heparin-Sepharose and gel filtration. The final preparation contained equimolar concentrations of PSA and PCI and was used for calibration of an ELISA for PSA:PCI complexes involving polyclonal anti-PSA and horseradish peroxidase-labeled anti-PCI antibodies. The ELISA had a detection limit of about 0.2 ng/ml of complex and was specific for PSA:PCI complexes because no color was developed at PSA or PCI concentrations up to 100 microgram/ml. Normal plasma or plasma from patients with prostate carcinoma who had high PSA levels had no detectable PSA:PCI complexes. Seminal plasma from voluntary donors collected in the absence of inhibitors and incubated at room temperature for at least 3 hours had PSA:PCI complex levels ranging from 30 to 46 micrograms/ml, accounting for up to 34% of the total PCI in seminal plasma.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A quantitative ELISA for the measurement of complexes of prostate-specific antigen with protein C inhibitor when using a purified standard. 750 42

Prostate-specific antigen (PSA) increases in the plasma of patients with prostate cancer, and has therefore been used as a reliable tumor marker. It has been demonstrated that prostate cancer cells over-express urokinase-type plasminogen activator (uPA), which plays an important role in tumor invasion and metastasis. We found that PSA converts the single-chain proform of urokinase-type plasminogen activator (scuPA) to an active 2-chain form. The active 2-chain uPA generated from scuPA by PSA was measured by hydrolyzation of S-2444, a synthetic substrate for uPA. PSA activated scuPA time- and dose-dependently. SDS-PAGE analysis revealed that, after incubation with PSA, the intensity of the 55-kDa band of scuPA decreased concomitantly with increases in the intensity of the 2 bands at 33 kDa and 22 kDa. Amino-acid-sequence analysis indicated that PSA cleaved Lys158-Ile159, which corresponds with the site cleaved by plasmin. PSA did not enhance or impair the activity of the 2-chain form of uPA. These findings imply that PSA could be an initiator of the protease cascade involved in prostate-cancer invasion and metastasis.
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PMID:Prostate-specific antigen activates single-chain urokinase-type plasminogen activator. 884 46

We found 5 cases of prostatic carcinoma with metastasis with alpha 2 macroglobulin (alpha 2 M) concentration below approximately 40 mg/dl in serum. All these patients had bone metastasis, and none of them had DIC. We found no other cases with such a low concentration of alpha 2 M. Their alpha 2 M level increased to normal level after treatment with transurethral resection of prostate or hormone agents, and the level was correlated with the clinical symptom. During the clinical course, their alpha 2 M level was negatively correlated with prostate-specific antigen (PSA) and prostatic acid phosphate (PAP). All these results suggest that alpha 2 M concentration in serum reflects the severity of prostatic carcinoma with metastasis and that alpha 2 M deficiency is an indicator of metastasis. The acute phase proteins of CRP and serum amyloid A did not increase in spite of the presence of metastasis in these patients with extremely low alpha 2 M level (< 20 mg/dl), suggesting that alpha 2 M is involved in the metabolism of these acute phase proteins. On immunohistochemical studies, their specimens of prostatic carcinoma gave positive stain for PSA and urokinase-type plasminogen activator (u-PA). Both PSA and u-PA formed a complex with alpha 2 M in vitro. The alpha 2 M deficiency in these patients might be due to the complex formation between alpha 2 M and these prostate-originated proteases and to the rapid disappearance of the complex.
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PMID:[Studies on alpha 2 macroglobulin deficiency in association with cancer metastasis]. 910 63

Our work was undertaken to compare the relative efficiency of 2 purified prostatic kallikreins, namely, hK2 and prostate-specific antigen (PSA or hK3), in the activation of single-chain urokinase (scuPA). We found that hK2 converts scuPA into an active enzyme with an efficiency equal to approximately 1/50 that of plasmin. During the activation of scuPA by hK2, two fragments of 33 and 22 kDa were generated. The NH2-terminal amino acid sequence of the 33 kDa fragment showed that hK2 cleaved scuPA between Lys158 and Ile159. In contrast to a previous report by another group, our purified hK3 preparation containing no trypsin-like contaminants was totally unable to activate scuPA. Our results show that kallikrein hK2 has plasmin-like activity and suggest that it could be the initiator of a proteolytic cascade leading to prostatic cancer invasion.
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PMID:Prostatic kallikrein hK2, but not prostate-specific antigen (hK3), activates single-chain urokinase-type plasminogen activator. 918 Jan 62

The precursor or zymogen form of prostate-specific antigen (pro-PSA) is composed of 244 amino acid residues including an amino-terminal propiece of 7 amino acids. Recombinant pro-PSA was expressed in Escherichia coli, isolated from inclusion bodies, refolded, and purified. The zymogen was readily activated by trypsin at a weight ratio of 50:1 to generate PSA, a serine protease that cleaves the chromogenic chymotrypsin substrate 3-carbomethoxypropionyl-L-arginyl-L-prolyl-L-tyrosine-p-nitroanili ne- HCl (S-2586). In this activation, the amino-terminal propiece Ala-Pro-Leu-Ile-Leu-Ser-Arg was released by cleavage at the Arg-Ile peptide bond. The recombinant pro-PSA was also activated by recombinant human glandular kallikrein, another prostate-specific serine protease, as well as by a partially purified protease(s) from seminal plasma. The recombinant PSA was inhibited by alpha1-antichymotrypsin, forming an equimolar complex with a molecular mass of approximately 100 kDa. The recombinant PSA failed to activate single chain urokinase-type plasminogen activator, in contrast to the recombinant hK2, which readily activated single chain urokinase-type plasminogen activator. These results indicate that pro-PSA is converted to an active serine protease by minor proteolysis analogous to the activation of many of the proteases present in blood, pancreas, and other tissues. Furthermore, PSA is probably generated by a cascade system involving a series of precursor proteins. These proteins may interact in a stepwise manner similar to the generation of plasmin during fibrinolysis or thrombin during blood coagulation.
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PMID:Characterization of the precursor of prostate-specific antigen. Activation by trypsin and by human glandular kallikrein. 926 Nov 79

Human prostatic epithelial cells constitutively secrete prostate-specific antigen (PSA), a kallikrein-like serine protease, which is a normal component of the seminal plasma. PSA is currently used as a specific diagnostic marker for the early detection of prostate cancer. We demonstrate that PSA degrades extracellular matrix glycoproteins fibronectin and laminin and, thus, may facilitate invasion by prostate cancer cells. Blocking PSA proteolytic activity with PSA-specific mAb results in a dose-dependent decrease in vitro in the invasion of the reconstituted basement membrane Matrigel by LNCaP human prostate carcinoma cells which secrete high levels of PSA. A novel PSA-SDS-PAGE zymography method for the detection of matrix degrading ability of PSA is also described. We propose that: (a) because of the dysplastic cellular disorganization in early neoplastic lesions called prostatic intraepithelial neoplasia (PIN), PSA may be secreted not only at the luminal end but also, abnormally, at the cell-basement membrane interface, causing matrix degradation and facilitating invasion; and (b) PSA, along with urokinase, another serine protease secreted by prostatic epithelium, may be involved in the proteolytic cascade during prostate cancer invasion and metastasis. The discovery of the extracellular matrix degrading ability of PSA not only makes it a marker for early detection but also a target for prevention and intervention in prostate cancer.
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PMID:Prostate-specific antigen, a serine protease, facilitates human prostate cancer cell invasion. 981 98

Human kallikrein 2 (hK2) is a serine protease expressed predominantly in the prostate which has 80% homology to prostate-specific antigen (PSA). hK2 is an active trypsin-like protease which has been shown by immuno-histochemical staining to be more highly expressed in prostate carcinoma than in benign prostate tissue. Unlike PSA, hK2 activates pro-PSA , pro-hK2 and the zymogen form of urokinase-type plasminogen activator (uPA), an extracellular protease correlated with prostate cancer and metastasis. We show here that hK2 rapidly forms a complex with plasminogen activator inhibitor-1 (PAI-1), the primary inhibitor of uPA in tissues. In addition, hK2 inactivated 6 to 7 mol of PAI-1 by cleavage at Arg346-Met347 for every mole of hK2-PAI-1 complex formed. In contrast with hK2, PSA neither complexed with nor inactivated PAI-1. PAI-1 inhibited hK2 comparably with protein C inhibitor (PCI) and at least 20 times more rapidly than alpha1-anti-chymotrypsin (ACT). N-Terminal sequencing shows that hK2 forms a covalent complex with PAI-1, PCI and ACT after cleavage at Arg346-Met347, Arg354-Ser355 and Leu358-Ser359, respectively. During complex formation, hK2 inactivated PAI-1 but did not inactivate ACT or PCI. Our current results suggest that the increased hK2 expression in prostate cancer tissues could influence cancer biology not only by activation of uPA but also by inactivation of its primary inhibitor, PAI-1.
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PMID:Prostatic human kallikrein 2 inactivates and complexes with plasminogen activator inhibitor-1. 1020 59

Human glandular kallikrein 2 (hK2) is a serine protease expressed by the prostate gland with 80% identity in primary structure to prostate-specific antigen (PSA). Recently, hK2 was shown to activate the zymogen form of PSA (proPSA) in vitro and is likely to be the physiological activator of PSA in the prostate. hK2 is also able to activate urokinase and effectively cleave fibronectin. We studied the substrate specificity of hK2 and regulation of its activity by zinc and extracellular protease inhibitors present in the prostate and seminal plasma. The enzymatic activity and substrate specificity was studied by determining hK2 cleavage sites in the major gel proteins in semen, semenogelin I and II, and by measuring hydrolysis of various tripeptide aminomethylcoumarin substrates. HK2 cleaves substrates C-terminal of single or double arginines. Basic amino acids were also occasionally found at several other positions N-terminal of the cleavage site. Therefore, the substrate specificity of hK2 fits in well with that of a processor of protein precursors. Possible regulation mechanisms were studied by testing the ability of Zn2+ and different protease inhibitors to inhibit hK2 by kinetic measurements. Inhibitory constants were determined for the most effective inhibitors PCI and Zn2+. The high affinity of PCI for hK2 (kass = 2.0 x 10(5) M-1 x s-1) and the high concentrations of PCI (4 microM) and hK2 (0.2 microM) in seminal plasma make hK2 a very likely physiological target protease for PCI. hK2 is inhibited by Zn2+ at micromolar concentrations well below the 9 mM zinc concentration found in the prostate. The enzymatic activity of hK2 is likely to be reversibly regulated by Zn2+ in prostatic fluid. This regulation may be impaired in CAP and advanced metastatic cancer resulting in lack of control of the hK2 activity and a need for other means of control.
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PMID:Enzymatic action of human glandular kallikrein 2 (hK2). Substrate specificity and regulation by Zn2+ and extracellular protease inhibitors. 1041 40

Tumor-associated proteases play a major role in determining the biologic behavior and aggressiveness of prostate cancer. Several authors have described the association between the increased levels of urokinase plasminogen activator in the plasma and in the malignant prostatic tissue with the metastatic potential of prostate cancer. However, the direct effect of this activity in producing fibronogenolysis in patients with prostate cancer has not been addressed. To evaluate the role of chemotherapy in reversing fibrinogenolysis in patients with prostate cancer, eight patients with hormone-refractory prostate cancer, bleeding, and laboratory evidence of primary hyperfibrinogenolysis were treated with docetaxel. The drug was given 48 hr after initiation of all supportive measures. Laboratory data, including plasminogen, alpha 2-antiplasmin, and fibrinogen, were recorded before and after treatment. Prostate-specific antigen (PSA) was measured at the time of referral and before subsequent cycles (3 weeks). Five patients had resolution of the fibrinolytic process after one cycle of treatment with docetaxel. This was demonstrated by improvement in both the laboratory parameters and the bleeding episodes. Further follow-up showed stabilization of the hematologic parameters and reduction in PSA values in these patients. Two patients died from uncontrolled bleeding despite all supportive measures. One patient did not demonstrate response to this treatment in terms of normalization of the fibrinolytic indicators or reduction in PSA. Primary fibrinogenolysis associated with metastatic prostate cancer is a serious complication. Docetaxel appears to be effective in reversing this process in some hormone-refractory patients. Although this response appears to be due to antitumor activity, a direct effect on the fibrinolytic pathway induced by the tumor cannot be excluded. Further work in this area is warranted.
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PMID:Reversion of primary hyperfibrinogenolysis in patients with hormone-refractory prostate cancer using docetaxel. 1075 87


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