Expression of urokinase-type plasminogen activator receptor and plasminogen activator inhibitor-1 in gastric cancer

In gastric cancer, the urokinase-type plasminogen activator (uPA) system plays important roles in invasion and metastasis, processes which entail proteolysis and adhesion. Both the urokinasetype plasminogen activator receptor (uPAR) and the plasminogen activator inhibitor-1 (PAI-1) are thought to be important factors in this system. To clarify the relationship between these two factors and gastric cancer invasiveness, we evaluated the expression of uPAR and PAI-1 in 91 cases of gastric cancer by immunohistochemistry and in situ hybridization. Urokinase-type plasminogen activator receptor-mRNA, PAI-1-mRNA, uPAR and PAI-1 protein were diffusely distributed in the cytoplasm of the cancer cells and concentrated at invasive foci. Urokinase-type plasminogen activator receptor protein expression correlated with lymphatic, venous invasion (P<.01) and lymph node metastasis (P<0.05); uPAR-mRNA expression correlated with lymphatic, venous invasion and lymph node metastasis (P<0.05). Plasminogen activator inhibitor-1 protein expression correlated with lymphatic, venous invasion, lymph node metastasis and depth of invasion (P<0.01); PAI-1-mRNA expression was linked to lymphatic, venous invasion (P<0.01), lymph node metastasis and depth of invasion (P<0.05). This suggests that the proteolytic activity of uPAR and the cellular motility of PAI-1 in gastric cancer cells may determine penetration of lymphatic and blood vessels, whereby lymph node metastasis may be promoted and that the promotion of cellular motility by PAI-1 may influence the depth of cancer invasion.     

Expression of urokinase-type plasminogen activator and its receptor in gastric fibroblasts and effects of nonsteroidal antiinflammatory drugs and prostaglandin

In acute inflammatory condition, little is known about the expression of the urokinase-type plasminogen activator (uPA) and its receptor (uPAR) in the gastric fibroblasts. To clarify the role of human gastric fibroblasts in acute inflammatory conditions such as gastric ulcer, the effects of interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha on the expression of uPA and uPAR, which were suggested to be associated with tissue remodeling, in gastric fibroblasts were investigated. The expression level of uPA mRNA and the amount of uPA antigen increased significantly on treatment with each concentration of IL-1beta (1 and 10 ng/ml) and 10 ng/ml TNF-alpha. On the other hand, the amounts of uPA antigen on cell surfaces were not affected significantly by IL-1beta and TNF-alpha stimulation. The expression level of uPAR mRNA increased in a dose-dependent manner on IL-1beta stimulation. The effect of indomethacin on uPA and uPAR expression in these cells was also examined. When gastric fibroblasts were treated with 50 microM indomethacin, the expression level of uPA mRNA decreased significantly, and the amount of uPA antigen in the culture medium and on cell surfaces decreased significantly with indomethacin in a dose-dependent manner. The increased uPAR mRNA expression caused by IL-1beta was reduced to the basal level by treatment with 50 microM indomethacin. Furthermore, we investigated the role of prostaglandin E2 (PGE2), which is suggested to play major roles in acute inflammation of the stomatch, on uPA and uPAR expression in gastric fibroblasts. The expression level of uPAR mRNA and the amount of uPA antigen on cell surfaces increased in a dose-dependent manner on treatment with PGE2 (10 and 50 ng/ml). These results suggest that uPA and uPAR expression in gastric fibroblasts is involved in the regulating system of PGE2 and that NSAIDs may delay healing of gastric mucosal injury in part through suppressing uPA production via inhibition of endogenous PG production.     

类风湿关节炎中尿激酶型纤溶酶原激活物及其受体蛋白和基因的表达

目的　检测尿激酶型纤溶酶原激活物 (uPA)及其受体 (uPAR)蛋白和mRNA在类风湿关节炎 (RA)的表达 ,探讨uPA、uPAR基因在RA细胞外基质降解中的作用。方法　采用免疫组化和cDNA mRNA原位分子杂交技术分别检测了 2 4例RA、18例骨关节炎 (OA)和 6例正常滑膜组织中uPA、uPAR蛋白和mRNA的分布及表达情况。结果　 2 4例RA滑膜组织均呈uPA、uPAR蛋白和mRNA的阳性表达 ,uPA、uPAR蛋白的强阳性率高于mRNA。uPA、uPAR蛋白和mRNA阳性信号主要分布在RA滑膜衬里细胞、滑膜下层单核细胞、巨噬细胞样细胞及血管内皮细胞 ;18例OA滑膜组织中 ,uPA、uPAR蛋白和mRNA的表达部位类似于RA ,但阳性率、阳性程度及分布范围均明显低于RA滑膜组织 ,两组之间蛋白和mRNA表达的差异均有显著性 (P <0 0 1或P <0 0 0 1)。 6例正常滑膜组织呈阴性反应。结论　RA滑膜组织存在高水平uPA、uPAR蛋白和mRNA的表达 ,提示在RA的发生发展过程中 ,uPA和uPAR基因起着重要作用 ;RA和OA中uPA、uPAR基因表达水平的差异 ,可能与这两种疾病软骨和骨基质降解的程度及进程等临床表现密切相关     

Single-chain urokinase-type plasminogen activator bound to its receptor is relatively resistant to plasminogen activator inhibitor type 1

Urokinase-type plasminogen activator (uPA) is synthesized as single- chain protein (scuPA) with little intrinsic activity. scuPA is activated when it is converted to two-chain urokinase (tcuPA) by plasmin or when it binds as a single-chain molecule to its cellular receptor (uPAR). Previous data indicate that complexes between scuPA and its receptor have somewhat higher affinity for plasminogen than does tcuPA. The current study indicates that plasminogen activator activity of scuPA bound to recombinant, soluble uPAR (suPAR) is also fivefold less sensitive to inhibition by plasminogen activator type 1 (PAI-1) than is soluble or receptor-bound tcuPA. Binding of PaI-1 to suPAR/scuPA complexes is totally reversible and can be overcome by increasing the concentration of plasminogen, suggesting a competitive mechanism of inhibition (Ki = 18 nmol/L). Binding of scuPA to suPAR also retards its cleavage by plasmin. These results indicates that binding of single-chain urokinase to its receptor promotes its activity, retards its inhibition, and protects it from conversion to a two-chain form of the enzyme, a step that may precede its inactivation and clearance from cell surfaces. These results are consistent with a physiologic role for receptor-bound single-chain urokinase as a cellular plasminogen activator.     

肺癌患者血浆尿激酶受体的检测及其临床意义

目的　研究肺癌患者血浆中尿激酶受体 (uPAR)的表达 ,探讨uPAR与肺癌浸润转移及预后的关系。方法　2 0 0 2 - 0 4 2 0 0 2 - 12苏州大学附属第二医院采用酶联免疫吸附试验方法 (ELISA)检测 2 6名正常健康者及 5 4例肺癌患者血浆中可溶性尿激酶受体 (suPAR)的质量浓度。结果　肺癌患者血浆suPAR质量浓度显著高于健康对照组 (P <0 0 0 1) ,并与TNM分期 (Ⅱ、Ⅲ、Ⅳ期 )相关 (P <0 0 5 )。结论　suPAR在肺癌的生长、侵袭转移过程中起着重要的作用 ,检测其在血浆中的表达有助于判断患者的病情及预后     

Unique secretory dynamics of tissue plasminogen activator and its modulation by plasminogen activator inhibitor-1 in vascular endothelial cells

We analyzed the secretory dynamics of tissue plasminogen activator (tPA) in EA.hy926 cells, an established vascular endothelial cell (VEC) line producing GFP-tagged tPA, using total internal reflection-fluorescence (TIR-F) microscopy. tPA-GFP was detected in small granules in EA.hy926 cells, the distribution of which was indistinguishable from intrinsically expressed tPA. Its secretory dynamics were unique, with prolonged (> 5 minutes) retention of the tPA-GFP on the cell surface, appearing as fluorescent spots in two-thirds of the exocytosis events. The rapid disappearance (mostly by 250 ms) of a domain-deletion mutant of tPA-GFP possessing only the signal peptide and catalytic domain indicates that the amino-terminal heavy chain of tPA-GFP is essential for binding to the membrane surface. The addition of PAI-1 dose-dependently facilitated the dissociation of membrane-retained tPA and increased the amounts of tPA-PAI-1 high-molecular-weight complexes in the medium. Accordingly, suppression of PAI-1 synthesis in EA.hy926 cells by siRNA prolonged the dissociation of tPA-GFP, whereas a catalytically inactive mutant of tPA-GFP not forming complexes with PAI-1 remained on the membrane even after PAI-1 treatment. Our results provide new insights into the relationship between exocytosed, membrane-retained tPA and PAI-1, which would modulate cell surface-associated fibrinolytic potential.     

Hyperglycemia is associated with lower levels of urokinase-type plasminogen activator and urokinase-type plasminogen activator receptor in wound fluid

AimsWounds in patients with hyperglycemia show impaired healing. Plasminogen activation is crucial in several overlapping phases of wound healing process. In this study, we aimed i) to compare acute wound fluid in patients with hyperglycemia and normoglycemia, ii) to focus on the elements of plasminogen activation in the wound fluid, and iii) to determine if the acute wound fluid characteristics are associated with surgical site infections.MethodsIn a cohort of 54 patients, a closed suction drain was placed in the wound above the anterior abdominal wall fascia under the skin in order to collect postoperative acute wound fluid samples for 3 following days after colorectal surgery. Patients were classified as normoglycemic (n = 25) or hyperglycemic (n = 29; 17 with type 2 diabetes and 12 with stress induced hyperglycemia). Surgical site infection was defined according to the Centers for Disease Control criteria. The levels of urokinase-type plasminogen activator (uPA), urokinase-type plasminogen activator receptor (uPAr), plasminogen activator inhibitor-1 (PAI-1), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and fibroblast growth factor-1 (FGF-1) were measured in the wound fluid.ResultsCompared to normoglycemic subjects, patients with hyperglycemia had significantly lower levels of uPA and uPAr in the wound fluid despite similar or even higher circulating levels. There was no significant difference in IL-1β, TNF-α, PAI-1 and FGF-1 levels. In the whole study population, the wound fluid levels of uPA and uPAr were negatively correlated with circulating glucose levels. No difference was detected in the wound fluid characteristics of patients with and without surgical site infection.ConclusionPatients with hyperglycemia exhibit decreased levels of uPA and uPAr in the wound fluid, suggesting a local failure in plasminogen activation at the wound site.     

Helicobacter pylori neutrophil-activating protein stimulates tissue factor and plasminogen activator inhibitor-2 production by human blood mononuclear cells

Helicobacter pylori neutrophil-activating protein (HP-NAP) is a virulence factor that activates phagocytic NADPH-oxidase. The effect of HP-NAP on the production of tissue factor (TF), plasminogen activator inhibitor-2 (PAI-2), and urokinase-type plasminogen activator (u-PA) by human blood mononuclear cells (MNC) was evaluated by using functional and immunological assays and mRNA analysis. HP-NAP induced time- and dose-dependent increases in TF and PAI-2, with a maximal effect at 300 nmol/L (>15-fold increase in antigens). No changes in u-PA were observed. When whole bacteria were used, an H. pylori mutant lacking HP-NAP was significantly less active than the wild-type strain. MNC from a patient with chronic granulomatous disease behaved as do normal cells, which indicates that HP-NAP effects can occur independently of NADPH-oxidase. HP-NAP, by inducing the coordinate expression of cell procoagulant and antifibrinolytic activities, might favor fibrin deposition and contribute to the inflammatory reaction of gastric mucosa elicited by H. pylori.     

FDP D-dimer induces the secretion of interleukin-1, urokinase-type plasminogen activator, and plasminogen activator inhibitor-2 in a human promonocytic leukemia cell line.

We studied the effect of fibrinogen degradation products D, E, and D-dimer on a human promonocytic leukemia cell line, NOMO-1. After exposure to a 10(-5)-mol/L fragment D or D-dimer, the cells displayed macrophage-like characteristics, such as adherence to plastic surfaces, and showed approximately a twofold increase in response to the nitroblue tetrazolium reduction test. The secretion of interleukin-1 alpha (IL-1 alpha) into the medium was markedly stimulated by a 10(-5)-mol/L fragment D, E, and D-dimer, whereas a significant increase in IL-1 beta secretion was observed only in D-dimer-stimulated cells. In addition, D-dimer induced a rapid increase in urokinase-type plasminogen activator on day 1 (0.52 +/- 0.02 ng/mL v 0.07 +/- 0.01 ng/mL in the control culture) and a slow increase in plasminogen activator inhibitor-2 on day 5 (3.9 +/- 1.6 ng/mL v 1.2 +/- 0.2 ng/mL in the control culture). An increase in tissue factor (TF) was also demonstrated on the cell surface of NOMO-1 cells exposed to fragment D or D-dimer by indirect immunofluorescence using an anti-TF monoclonal antibody. Scatchard plot analysis showed that fragment D and D-dimer bound to the NOMO-1 cells with a kd of 3.3 nmol/L and 2.7 nmol/L, respectively. These results suggest that fragment D-dimer specifically stimulates cells of monocyte-macrophage lineage to secrete key substances that regulate blood coagulation, fibrinolysis, and inflammation.     

Tissue plasminogen activator,plasminogen activator inhibitor-1 and von willebrand factor in rheumatoid arthritis

Summary Tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF), all of endothelial origin and active in the haemostasis, were analysed in 74 patients with rheumatoid arthritis. The concentrations were related to extra-articular disease and to the incidence of thromboembolic events (TE) registered in a 2-year follow-up period. Patients with extra-articular disease had a significant increase in PAI-1 activity and reduced tPA release in the venous occlusion test. von Willebrand factor, PAI-1 and also haptoglobin and triglycerides were significantly increased in the group of patients who later suffered from TE. In a multiple regression model, in which cholesterol, triglycerides and lipoprotein (a) showed significant association with TE, vWF had the strongest additive explanatory value. No distinct acute phase pattern of PAI-1 was found in any patient subgroup.     

Effect of combined AT1 receptor and aldosterone receptor antagonism on plasminogen activator inhibitor-1

Aldosterone enhances angiotensin II (Ang II)-induced plasminogen activator inhibitor (PAI)-1 expression in vitro. This study tested the hypothesis that angiotensin II type 1 (AT(1)) and aldosterone receptor antagonism interact to decrease PAI-1 in humans. Effects of candesartan (16 mg/d), spironolactone (25 mg/d), or combined candesartan/spironolactone on mean arterial pressure (MAP), endocrine, and fibrinolytic variables were measured in 18 normotensive subjects [age 33.7 yr (95% confidence interval 29.3, 38.0), body mass index 26.6 (24.7, 28.4) kg/m(2)] in whom the renin-angiotensin-aldosterone system was activated by furosemide (20 mg/d). Candesartan [83.3 mm Hg (78.9, 87.7)], but not spironolactone [89.4 mm Hg (85.4, 93.5)], decreased MAP, compared with baseline [92.2 mm Hg (88.9, 95.5), P < 0.001] and furosemide alone [89.1 mm Hg (85.7, 92.4), P = 0.002]. Coadministration of spironolactone with candesartan did not further decrease MAP. Candesartan dramatically increased Ang II [177.9 pg/ml (113.3, 242.6)], compared with baseline [34.8 pg/ml (29.3, 40.4), P = 0.002] and furosemide alone [40.6 pg/ml (29.7, 51.5), P = 0.003]. Spironolactone increased Ang II [51.5 pg/ml (41.3, 61.7), P = 0.014 vs. baseline, P = 0.004 vs. candesartan]. There was no additive effect of candesartan and spironolactone on Ang II [197.6 pg/ml (134.2, 261.0)]. Aldosterone was lower during candesartan [8.9 ng/dl (7.3, 10.6), P = 0.007] than during furosemide alone [14.1 ng/dl (10.9, 17.3), P = 0.007], spironolactone [18.7 ng/dl (14.5, 22.9), P = 0.002], or combined candesartan/spironolactone [13.9 ng/dl (11.8, 15.9), P = 0.006]. Furosemide increased PAI-1 antigen [27.8 ng/ml (20.6, 35.0), P = 0.002 vs. 19.3 ng/ml (13.4, 25.2) baseline], even in the presence of candesartan [27.2 ng/ml (16.5, 37.8), P = 0.042 vs. baseline] or spironolactone [27.3 ng/ml (17.9, 36.8), P = 0.015 vs. baseline]. However, coadministration of AT(1) and aldosterone receptor antagonists prevented the furosemide-induced increase in PAI-1 [19.2 ng/ml (9.8, 28.6), P = 0.974 vs. baseline, P < 0.05 vs. candesartan, spironolactone or furosemide alone]. This study evidences an interactive effect of endogenous Ang II and aldosterone on PAI-1 production in humans.     

The structure of the urokinase-type plasminogen activator receptor gene

The cellular receptor for urokinase-type plasminogen activator (uPAR) is a glycosylphosphatidylinositol (GPI)-anchored membrane protein that plays a central role in pericellular plasminogen activation. It contains 313 amino acid residues, including 28 cysteine residues in a pattern of three homologous repeats. The cysteine residue pattern suggests that uPAR belongs to a superfamily of proteins including CD59, murine Ly-6, and a variety of elapid snake venom toxins. A novel 1.7-kb uPAR cDNA was isolated that is missing exon 5 and that contains 380 bp not previously reported at the 5' end. This cDNA was used to probe a human genomic library from which three clones were isolated and analyzed. The uPAR gene consists of 7 exons spread over 23 kb of genomic DNA. Exons 2, 4, and 6 code for homologous domains within the mature protein, as do exons 3, 5, and 7; CD59-like homologous pairs are encoded by exons 2-3, 4-5, and 6-7, respectively. The structure of the gene for uPAR further confirms the relationship of this molecule to the superfamily containing CD59, Ly-6, and the elapid snake venom toxins.     

肝硬化患者尿激酶型纤溶酶原激活物及其受体测定的临床意义

目的检测肝硬化患者血浆中尿激酶型纤溶酶原激活物(u-PA)及其受体(u-PAR)的含量,分析代偿期和失代偿期肝硬化患者纤溶活化的变化情况。方法 ELISA法检测48例肝硬化和30名健康志愿者的血浆中u-PA及其受体的含量。结果失代偿期肝硬化患者u-PA(1362±481ng.l~(-1))及u-PAR(1037±357ng.l~(-1))均明显高于对照(P<0.05,P<0.05),且u-PA高于代偿期肝硬化患者(P<0.05)结论肝硬化患者存在明显的纤溶活性增强,并随病情的加重而增加。     

Invasion and metastasis of hepatocellular carcinoma in relation to urokinase-type plasminogen activator, its receptor and inhibitor

This study was designed to investigate the relationship of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), and plasminogen activator inhibitor type-1 (PAI-1) to invasion and metastasis of hepatocellular carcinoma (HCC). The expression of uPA, uPAR, and PAI-1 in HCC was determined by immunohistochemistry, Northern blot, and an LCI-D20 nude mouse metastatic model of HCC. The over-expression of uPA, uPAR, and PAI-1 was found in HCC, especially in the patients with portal cancer embolus, tumor invasion, and metastasis. Immunohistochemistry results showed that the rate of positive staining of uPA, uPAR, and PAI-1 were higher in HCC than those in the control groups consisting of cancer-adjacent tissue and normal liver tissue. In the case of HCC invasion, positive uPA and uPAR were seen in 16 and 19 out of 22 patients, respectively (P < 0.01 and P < 0.001, respectively, as compared with the patients without invasion). In those with portal cancer embolus and tumor metastasis, positive uPAR was eight out of eight and six out of six patients. In those with tumor recurrence, positive uPAR was 15 out of 17 patients (P < 0.01 vs no recurrence). In patients who died within 2 years after surgery, positive uPAR was 12 out of 12 patients (P < 0.01 vs survival), and positive PAI-1 was nine out of 12 patients (P < 0.05 vs survival). In those in which uPA, uPAR, and PAI-1 were all positive staining, stronger cancer invasiveness and higher mortality were found (P < 0.05 vs patients with all negative staining). In 30 patients tested with Northern blot analysis, the results were similar to those tested with immunohistochemistry. Higher expression of uPA mRNA and PAI-1 mRNA were detected in tumor tissues and embolus. In the patients with positive signals of uPA mRNA and PAI-1 mRNA, invasive cases were found in seven out of 19 and eight out of 18 patients, respectively, which were significantly higher than those showing negative signals (P < 0.05). In the LCI-D20 nude mouse metastatic model of HCC (MMHCC), PAI-1 activity in plasma and tumor tissue increased with tumor growth, invasion, and metastasis. At an advanced stage of MMHCC, PAI-1 activity rose to 15.4 ± 0.7 Au/ml in plasma and 0.8 ± 0.3 Au/mg in tumor extracts, which was significantly higher than 6.2 ± 1.8 Au/ml in plasma and 0.4 ± 0.1 Au/mg in extracts at an early stage (P < 0.05). PAI-1 activity related to the changes of serum AFP and tumor progress were r=0.9544 and r=0.9648, respectively (P < 0.05). The data suggest that the expression of uPA, uPAR, and PAI-1 is increased in HCC, and related to the invasiveness, metastasis, and prognosis of HCC. Received: 30 September 1999 / Accepted: 10 March 2000     

Interleukin-1beta regulates urokinase plasminogen activator (u-PA), u-PA receptor, soluble u-PA receptor, and plasminogen activator inhibitor-1 messenger ribonucleic acid expression in cultured human endometrial stromal cells

The interleukin-1 (IL-1) system plays an integral role in local intercellular interactions during implantation. In addition, the plasminogen activator system, especially urokinase plasminogen activator (u-PA), plasminogen activator inhibitor (PAI-1), and u-PA receptor (u-PAR), are crucial during embryo implantation. Decidualization and implantation are complex processes dependent upon several proteases, including u-PA, and IL-1 is known to affect PA activity in several cell types. We investigated the role of IL-1beta in regulating u-PA, PAI-1, u-PAR, and soluble u-PAR messenger ribonucleic acid (mRNA) expression in cultured human endometrial stromal cells using quantitative competitive PCR. For confirmation of the mRNA data, we measured PAI-1 and u-PAR protein by enzyme-linked immunosorbent assay. Confluent stromal cell cultures treated with progesterone and estradiol for 9 days were stimulated with IL-1beta, and IL-1beta plus IL-1beta antibody for an additional 24 h. Total RNA was extracted, reverse transcribed, and coamplified using quantitative and competitive PCR with internal standards. IL-1beta increased PAI-1, u-PAR, and soluble u-PAR expression in a dose-dependent manner, and this result was reversed by anti-IL-1beta antibody treatment. u-PA mRNA expression was not dependent on IL-1beta. These results suggest that IL-1 may be important in regulating PAI-1 and u-PAR during stromal cell decidualization before implantation.     

Expression and functional role of urokinase-type plasminogen activator receptor in normal and acute leukaemic cells

Urokinase-type plasminogen activator receptor (UPA-R-CD87) is a GPI-anchored membrane protein which promotes the generation of plasmin on the surface of many cell types, probably facilitating cellular extravasation and tissue invasion. A flow cytometric quantitative analysis of expression levels for UPA-R was performed on fresh blast cells from patients with acute myeloid leukaemia (AML, n = 74), acute lymphoblastic leukaemia (ALL, n = 24), and biphenotypic leukaemia (BAL, n = 3) using two CD87 monoclonal antibodies (McAbs) (3B10 and VIM5). Peripheral blood and bone marrow (BM) cells from 15 healthy adults served as controls. Using 3B10 McAb, UPA-R was expressed (>99%) by blood monocytes, neutrophils, and BM myelomonocytic precursors in controls, whereas resting T and B lymphocytes, and CD34⁺ cells were UPA-R negative. We also attempted to clarify whether UPA-R has a role in mediating neutrophil functions. Oriented locomotion induced by different chemotaxins and lysozyme release by granules stimulated with fMLP or PMA were significantly decreased when UPA-R was neutralized by CD87 McAb. In contrast, the anti-UPA-R McAb had no effect on superoxide anion generation of normal neutrophils. Blasts from AML showed a heterogenous pattern of expression for the UPA-R McAbs, with reactivity strictly dependent on FAB subtype. The highest UPA-R expression was seen in the M5 group: all patients tested (n = 20) showed strong positivity for the UPA-R McAb whereas only 12% (3/24) of ALL patients were CD87 positive, and 2/3 of BAL patients showed a dim expression for CD87. The number of receptors expressed by blast cells in 6/74 (8.1%) AML patients was higher than those of normal samples; in addition, since co-expression of UPA-R and CD34 was not found in normal haemopoietic cells, it may be postulated that CD87 can be used alone (when overexpressed) or in combination with CD34 for the detection of minimal residual disease. Results also indicated that patients with UPA-receptors >12 × 10³ ABC/cell, irrespective of FAB subtype, had a greater tendency for cutaneous and tissue infiltration and a higher frequency of chromosome abnormalities, thus suggesting the concept that cellular UPA-R content positively correlates with the invasive potential of AML cells. The combination of higher UPA-R positivity, abnormalities of chromosome 11, and M5 FAB morphology may identify a peculiar subset of AML, characterized by a more aggressive clinical course.     

Regulation of plasminogen activator inhibitor-1 secretion by urokinase and tissue plasminogen activator in rat epithelioid-type smooth muscle cells

Tissue plasminogen activator (tPA) and urokinase (uPA) are targets of plasminogen activator inhibitor-1 (PAI-1) inhibition. We have previously shown that both proteases can also induce PAI-1 secretion in rat smooth muscle cells (SMCs). We now report that both proteases appear to use very similar cellular mechanisms for signal transduction. They induced PAI-1 secretion using a pathway(s) involving protein kinase C (PKC). They also activated the Raf/Mek/mitogen-activated protein kinase (MAPK) pathway, which lies downstream of PKC activation. Activation of protein kinase A (PKA), however, lowered PAI-1 secretion induced by uPA and tPA, as a result of an inhibition of the PKC pathway and inhibition of Raf, Mek and MAPK phosphorylations. Src and syk family non-receptor tyrosine kinases (TK) were also involved in PAI-1 induction. The mechanisms of interaction of these tyrosine kinases with other pathways appeared to be quite different: src appeared to act within the PKC and PKA pathways, while syk operated independently of these pathways. Furthermore, whereas src inhibition resulted in inhibition of Raf/Mek/Erk phosphorylations, syk inhibition could only inhibit Mek and Erk phosphorylations but not the phosphorylation of Raf. These multiple pathways utilized by uPA and tPA to modulate PAI-1 secretion might be involved in determining the proteolytic or antiproteolytic potential of the SMCs under different pathophysiological conditions.     

Lysophosphatidylcholine induces urokinase-type plasminogen activator and its receptor in human macrophages partly through redox-sensitive pathway

Urokinase-type plasminogen activator (uPA) and its cell surface receptor (uPAR) have been shown to be expressed in macrophages in atherosclerotic arterial walls, but the regulatory mechanisms of their expression remain unclear. The present study was performed to examine the effects of lysophosphatidylcholine (lysoPC), an important atherogenic lipid, on the expression of uPA and uPAR in human monocyte-derived macrophages. LysoPC upregulated the mRNA expression of uPA and uPAR, and it increased the protein expression of uPA in the culture medium and bound to the cell surface and of uPAR in the particulate fraction of the cells. LysoPC significantly increased the binding of the amino-terminal fragment of uPA to the treated cells and the cell-associated plasminogen activator activity. LysoPC stimulated superoxide anion production and increased intracellular oxidant levels in the cells. The combined incubation with reduced glutathione diethyl ester or N-acetylcysteine, antioxidants, suppressed the upregulation of uPA and uPAR mRNA and the increase in plasminogen activator activity by lysoPC. uPA and uPAR mRNA expression was also induced by the incubation with xanthine and xanthine oxidase, a superoxide anion-generating system. The results suggest that lysoPC increased the expression of uPA and uPAR and their functional activities in human monocyte-derived macrophages, at least in part through a redox-sensitive mechanism. This coordinate increase in the expression of uPA and uPAR in human macrophages by lysoPC could play an important role in plaque formation and disruption, arterial remodeling, and angiogenesis in atherosclerotic arterial walls.