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A growing body of evidence suggests that the plasminogen activator (PA) system is crucially involved in reproductive physiology in both sexes. Certain factors of the PA system have been found to be present in organs of the male reproductive tract in various species, and the presence of several of the factors was recently demonstrated in monkey testis. The present morphological study was therefore designed to investigate the occurrence and distribution of the tissue and urokinase plasminogen activators (t-PA and u-PA), the u-PA receptor (u-PAR) and the plasminogen activator inhibitors (PAI-1 and PAI-2) in normal human testis. Intraoperative specimens from seven patients undergoing orchidectomy or testicular biopsy were studied using in-situ hybridization (ISH) and immunohistochemistry (IHC). All five factors studied could be detected with both the ISH and IHC procedures. The ISH signals were localized to sites in the testicular tubules in a stage-specific manner. There was good correlation between results obtained with the two methods, though in IHC the tubules were stained more uniformly. The findings provide support for the involvement of the PA system in human male reproductive physiology. [ABSTRACT FROM AUTHOR]

The objective of this study was to elucidate the mechanisms involved in the formation of a functional decidua. The concentrations of plasminogen activators and plasminogen activator inhibitors in intrauterine decidua from normal and ectopic pregnancies were compared. Intrauterine decidua was obtained by curettage from 17 women with ectopic pregnancies and from five women with normal pregnancies. The gestational age was similar in the two groups. The antigen concentrations of plasminogen activators and plasminogen activator inhibitors in decidua homogenate were determined by ELISA and fibrinolytic activity was measured on fibrin plates. Localization was determined by immunohistochemical staining and mRNA was identified by in situ hybridization. Fibrinolytic activity was absent in decidua from normal pregnancies but present in the intrauterine decidua from ectopic pregnancies. High antigen concentrations of the inhibitors of fibrinolysis, PAI-1 and PAI-2, were found in normal decidua in contrast to low concentrations in decidua from ectopic pregnancies. Staining for PAI-1 as well as PAI-2 was positive in decidual cells. In situ hybridization resulted in high intensity signals for PAI-1 as well as for PAI-2 mRNA in decidua from normal pregnancies in contrast to very low intensity signals in decidua from ectopic pregnancies. The absence of proteolytic activity and high expression of PAI-1 and PAI-2 in normal decidua might facilitate attachment of the fertilized ovum and might also prevent detachment of the decidua.

Urokinase plasminogen activator (u-PA) plays a pivotal role in tissue degradation during tumor spread and metastasis. We have quantitated u-PA in tissue homogenates of 31 serous ovarian tumors and localized u-PA and its mRNA in tissue sections of 26 serous ovarian tumors. The content of u-PA was higher in malignant than in benign tumors, with the highest levels being found in poorly differentiated cancers. In tissue sections, the u-PA mRNA was hybridized with a radiolabeled RNA probe. Signals were almost exclusively found in the epithelium in benign and borderline tumors and in well-differentiated cancers. Poorly differentiated tumors and metastases exhibited prominent stromal expression of u-PA mRNA, whereas epithelial expression was weak or absent. Immuno-histochemical staining co-localized u-PA antigen with its mRNA in the epithelium of benign and borderline tumors and in well-differentiated cancers. Poorly differentiated malignant tumors showed extensive immunostaining in the epithelium in addition to stromal staining. The u-PA mRNA-expressing and u-PA-immunostained cells in the stroma were not tumor cells since no cells in the stroma were positive for cytokeratin. Poorly differentiated tumors had increased numbers of stromal macrophages (CD68), and they co-localized with some of the u-PA-positive cells. The presence of u-PA antigen and the absence of u-PA mRNA in tumor epithelium of poorly differentiated tumors and metastases together with the presence of u-PA mRNA in the stroma suggests production in stromal cells and subsequent binding to receptor sites in tumor cells.

The concentrations of the specific activators (u-PA and t-PA) and the specific inhibitors (PAI-1 and PAI-2) of the fibrinolytic system were analyzed in the peritoneal fluid in women suffering from intra-abdominal adhesions, endometriosis or pelvic inflammatory diseases (PID). Peritoneal fluids were collected from ten women in whom a laparotomy was performed and an additional 108 in whom a laparoscopy was carried out. In comparison with the normal control patients all activators and inhibitors were significantly increased in cases of PID and when a second-look laparoscopy was performed one week after laparotomy with adhesiolysis. At laparoscopies, when adhesions were verified, u-PA in the peritoneal fluid was significantly increased and in cases of endometriosis PAI-2 was significantly reduced. The start of a laparotomy in order to remove adhesions, initiates a process, resulting in a significant increase of PAI-2 antigen in the pelvic fluid. The results imply that the fibrinolytic system is comprehensively activated in the peritoneal cavity during ongoing inflammatory reaction, and after adhesiolysis. The increase in plasminogen activators in the peritoneal fluid in established cases of pelvic adhesions or endometriosis may indicate that the fibrinolytic system is continuously active to inhibit the further formation of adhesions.

Marked changes in the hemostasis system, especially increases in PAI-2, are observed during pregnancy and at delivery. This inhibitor is produced by placental trophoblasts and by macrophages. PAI-2 occurs in two forms, a LMW and a HMW form. LMW PAI-2 is intracellular, HMW PAI-2 is secreted. PAI-2 inhibits both u-PA and two-chain t-PA. PAI-2 seems to be involved in the processes of invasion and remodeling of fetal and uterine tissues. It may protect against premature placental separation and secure hemostasis at parturition. Excess levels of PAI-2 in amniotic fluid may protect membranes from premature rupture. An imbalance between fibrinolytic activators and inhibitors may also be related to intracranial hemorrhage in premature infants. During preeclampsia t-PA and PAI-1 levels are markedly increased in plasma, and in cases of intrauterine growth retardation, u-PA and PAI-2 levels are decreased. While elevated PAI-1 concentrations might be helpful markers of severity of preeclampsia, decreased PAI-2 levels seem to indicate decreased placental function and intrauterine growth retardation.

Malignant cells possess a high degree of proteolytic activity in which the plasminogen activator system plays an important role. An increased expression of urokinase type plasminogen activator (uPA) is of significance for degradation of the extracellular tumor matrix, facilitating invasiveness and growth. Inhibition of the active site of uPA makes it possible to evaluate the significance of uPA in tumor growth. We report here experiments on a uPA-producing human prostate xenograft (DU 145) using a competitive inhibitor of uPA, p-aminobenzamidine. In vitro experiments with DU 145 cells showed that p-aminobenzamidine caused a dose-dependent inhibition of uPA activity. DU 145 cells were inoculated s.c. in SCID mice and, once tumors were established, treatment with p-aminobenzamidine added to drinking water was started and lasted for 23 days. Mice receiving 250 mg/kg/day of p-aminobenzamidine showed a clear decrease in tumor-growth rate compared to the non-treated mice, resulting in 64% lower final tumor weight. In addition, uPA-antigen levels in the membrane fractions of DU 145 tumors from p-aminobenzamidine-treated mice were found to be decreased by 59%. We also show that p-aminobenzamidine has an anti-proliferative effect in cell culture at low cell number, correlating with a dose-dependent decrease in uPA production. In conclusion, we show that a low-molecular-weight uPA-inhibitor, p-aminobenzamidine, has a growth-inhibitory effect on a solid uPA-producing tumor.

Prostate cancer has a slow growing noninvasive phase, but, in general, is invasive on diagnosis. An initial step in the invasion of surrounding normal tissue is the activity of proteolytic enzymes such as components of the plasminogen activator system (PA). In cell culture, the primary human prostate cancer cell line 1013L expressed no urokinase type-PA (uPA), while DU 145, a cell line derived from a metastatic lesion, expressed high levels of uPA. The DU 145 cells grew easily as xenografts but the establishment of 1013L in the SCID mice was possible only with the aid of a gelatin sponge (Spongostan). The latency period was 42-64 days, followed by a slow growth phase before a fast growth phase occurred. This fast growth phase was characterized by rapid degeneration of tumor tissue, while high proliferation occurred around the blood vessels. On serial transplantation of tumor material, the growth pattern was similar. Furthermore, the 1013L tumor was encapsulated by connective tissue and no invasiveness could be detected. We found that 1013L tumor homogenates had hardly detectable levels of uPA, i.e., 300-fold lower than we found in the invasive prostate xenograft DU 145. In addition, no expression of uPA was found in the plasma of 1013L tumor-bearing mice whilst uPA antigen was detected in the plasma of DU 145 tumor-bearing mice. In conclusion, the 1013L cell line, which exhibits a nonaggressive pattern, could be a good model for studying progression of prostate cancer to a more aggressive phenotype in vivo and in vitro.

High concentrations of tissue plasminogen activator (t-PA) and placental type plasminogen activator inhibitor (PAI-2) have previously been found in gingival crevicular fluid (GCF) of adults and children. In the present study, intra-individual comparisons were made of the concentrations of t-PA, urokinase type plasminogen activator (u-PA), PAI-1, and PAI-2 in GCF from the same sites before and after periodontal treatment in eight healthy male volunteers aged 35-46 yr. The gingival state was assessed by exudate measurement, bleeding on standardized probing, and the gingival index of Löe & Silness 3 days before the start of the trial and on the day after completing a 21-day preventive program consisting of instruction and professional cleaning once a week. Eight sites per subject were selected for enzyme analyses, all showing improvement in gingival state during the period. Sampling of GCF at the start and at the end of the trial was done with small disks of Millipore-filter. t-PA and PAI-2 were analyzed with enzyme-linked immunosorbent assays with low method errors. The mean concentrations of t-PA were 0.73 mg/l before treatment and 0.49 mg/l after treatment. The mean concentrations of u-PA were 84.4 micrograms/l before treatment and 101.6 micrograms/l after treatment. PAI-1 was found in three subjects at the detection level. The mean PAI-2 concentrations were 2.19 mg/l before and 1.13 mg/l after treatment. The mean molar ratio PAs/PAI-2 was 0.47 before and 0.48 after treatment. This insignificant change implies a maintained proteolytic balance and indicates that PAI-2 is an important inhibitor of tissue proteolysis.