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)

We have identified a leukemia-differentiating activity (LDA) in medium conditioned by the LD-1 melanoma, a G-CSF secreting human tumor line. Partially-purified LDA induces HL-60 cells to produce superoxide, become phagocytic, and to develop macrophage-like morphology and surface markers. The LDA markedly suppresses clonal growth in agar of HL-60 cells, and cells of the human myeloid leukemia lines PBL 985 and K562, but does not suppress clonal growth of the B-lymphoblast lines Raji and Daudi. The molecular weight of this material is approx. 40,000 daltons. It can be separated from the bulk of the colony stimulating activity on phenyl sepharose chromatography. The LDA is not neutralized by antibodies to G-CSF, GM-CSF, IFN alpha, IFN gamma, TNF, urokinase, and tissue plasminogen activator, and is not inhibited by preincubation with aprotinin. The LDA in conditioned medium may be different from previously described differentiating factors, and may represent an additional class of human growth regulators.
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PMID:Leukemia-differentiating activity expressed by the human melanoma cell line LD-1. 316 98

Plasminogen activator (PA), a neutral protease whose primary function is to convert plasminogen to plasmin, is produced by various cells including macrophages, monocytes, endothelial cells, and tumor cells. This study reports the use of the chromogenic tripeptide substrate D-Val-Leu-Lys-p-nitroanilide (S-2251) and an automated microtiter plate reader spectrophotometer for the determination of PA activity in cells and fluids. There was a linear relationship between the time of incubation at 37 degrees C and the square root of the absorbance measured at 405 nm when urokinase was incubated with the substrate in the presence of plasminogen. There was no activity in the absence of plasminogen. The slopes of the lines (square root A 405/time) were directly related to the concentrations of urokinase, up through 0.05 CTA units. Using this assay, we determined the cellular activity of PA in human promyelocytic cells HL-60 (1.33 +/- 0.12 CTA units/mg), human monocytoid cells U937 (1.27 +/- 0.12 CTA units/mg), mouse myeloid leukemia cells RFM/UN (0.70 +/- 0.07 CTA units/mg), freshly isolated normal human monocytes (0.00 +/- 0.00 CTA units/mg), and human monocytes after 7 days in culture (5.66 +/- 0.38 CTA units/mg). There was a variable amount of activity expressed in freshly isolated cells or cell lysates of peritoneal macrophages from normal mice, or mice that had gotten intraperitoneal injections of peptone, thioglycollate, or NaIO4, but after 24 or 48 h of culture, these activities, in general, increased. Using this assay, PA levels in the euglobulin precipitates from human plasma prepared without venous occlusion (0.03 +/- 0.02 CTA units/mg protein) or after 5 min of venous occlusion of the arm (0.18 +/- 0.01 CTA units/mg) were comparable to those reported by others using different assays. Thus, this represents a simple, rapid, accurate assay of PA that should be useful to those in immunology, cell biology, and clinical medicine.
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PMID:Microassay for the photometric quantitation of cell-associated plasminogen activator using a chromogenic tripeptide substrate. 659 19

In myeloid leukemia, immature leukemic cells are able to egress into peripheral blood to infiltrate extra-medullary organs. We therefore analyzed the migrating and invasive potential of human HL-60 and NB4 cell lines, representative of acute myelogenous leukemia, their ability to express matrix metalloproteases (MMPs), tissue inhibitors of metalloproteases (TIMPs) and urokinase plasminogen activator (uPA) in response to differentiating agents. Granulocytic differentiation by all-trans-retinoic acid (ATRA) and aclacinomycin (ACLA) strongly increased HL-60 and NB4 cell migration and invasion. At mRNA and protein levels, these cell lines produced significant amounts of MMP-9 (HL-60<NB4). Granulocytic differentiation by ACLA increased both pro and active forms of MMP-9 whereas ATRA decreased them and stimulated uPA mRNAs. TIMP-1, the physiological MMP inhibitor, increased during granulocytic differentiation whereas TIMP-2 did not significantly vary. Use of Batimastat and aprotinin suggests that ATRA was active by modulating the uPA system while ACLA interfered with MMP expression. In conclusion, our data demonstrate that HL-60 and NB4 cells express MMPs and uPA which are differentially regulated by the differentiating agents ATRA and ACLA and suggest the clinical usefulness of MMPs and serine protease inhibitors in the prophylaxis and treatment of the ATRA syndrome.
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PMID:Matrix and serine protease expression during leukemic cell differentiation induced by aclacinomycin and all-trans-retinoic acid. 1184 92

We have previously shown that lysates from HL-60 myeloid leukemia cells or from peripheral blood monocytes are able to degrade alpha-actinin to form a 31-kDa amino-terminal fragment with monocyte/macrophage maturation promoting activity. In contrast, intact alpha-actinin, which is a 100-kDa actin-binding protein, has no differentiating activity. The aim of this study was to investigate the enzyme responsible for the degradation of alpha-actinin to form this fragment, named mactinin. The ability of cell lysates to degrade [125I]alpha-actinin in the presence of various enzyme inhibitors, including inhibitors of metalloproteinases, cysteine proteinases, and serine proteases, was measured. Phenylmethylsulfonyl fluoride (PMSF) was the only inhibitor able to prevent formation of mactinin by cell lysate degradation of alpha-actinin, suggesting that a serine protease is responsible for the digestion. Of the various serine proteases tested (thrombin, plasmin, and urokinase), only urokinase was able to produce a 31-kDa band. The urokinase-generated 31-kDa band promoted maturation in HL-60 cells. Amiloride, a specific inhibitor of urokinase, inhibited production of the 31-kDa alpha-actinin fragment by HL-60 cell lysates. For in vivo tests, inflammatory fluid (from bronchoalvelolar lavage) was collected from uPA (urokinase) knockout mice and their wild-type counterparts after intratracheal challenge with Pneumocystis carinii. Although most (6 of 8) wild-type mice had mactinin in their inflammatory fluid samples, none (0 of 8) of the uPA knockout mice had mactinin present (P<0.01). These results demonstrate that urokinase is necessary and sufficient for the formation of the monocyte/macrophage maturation promoting fragment, mactinin, in vitro and in vivo. These findings support the role of urokinase in the regulation of monocyte/macrophage functions, such as that occurring in inflammatory reactions.
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PMID:Urokinase is required for the formation of mactinin, an alpha-actinin fragment that promotes monocyte/macrophage maturation. 1218 60

HL-60, a cell line originating from a human myeloid leukemia, expresses urokinase-type plasminogen activator (uPA) on the mRNA level and secretes the protein into the culture supernatant. Additionally, uPA receptors (uPA-R) could be detected in HL-60 on both the mRNA and the protein level, whereas the lymphoblastic cell line Raji studied in parallel was uPA-R negative. The cell lines were further studied in their clonal growth in methylcellulose under the influence of rhuPA (rhpro-uPA). The growth of Raji cells was not influenced by rhuPA. Colony and cluster formation of HL-60 was not reproducibly affected by rhuPA in concentrations between 1-100 ng/ml. In some experiments however, there were higher numbers of colonies in the HL-60 cultures incubated with rhuPA which was due to a cluster-to-colony shift. Furthermore, the HL-60 colonies in the rhuPA incubated plates always showed morphological alterations including an adherent basis indicating functional differentiation. This assumption was further supported by the observation that the secondary plating efficiency (PE2) of HL-60 cells taken from single colonies of uPA-incubated plates decreased significantly when compared with PE2 of cells from colonies grown without the presence of uPA. In conclusion, the intact uPA molecule functions like an autocrine cytokine for a human leukemic cell line, which in addition to its effects in tumor invasion makes it an interesting target molecule for further studies on tumor suppression.
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PMID:Urokinase-type plasminogen-activator (upa), a protease with cytokine-like activity in human hl-60 leukemic-cell line. 2157 7