Prognostic impact of urokinase-type plasminogen activator (uPA) and its inhibitor (PAI-1) in cytosols and pellet extracts derived from 892 breast cancer patients

Prognostic significance of VEGF and components of the plasminogen activator system in endometrial cancer

Objective

The plasminogen activator system (PAS) and vascular endothelial growth factor (VEGF) are important in the carcinogenesis and play a key role in cancer invasion and mediating metastasis of carcinomas. The aim of the study was to evaluate the correlation of serum levels of VEGF and components of the PAS with clinicopathological risk factors and outcome in patients with endometrial cancer (EC).

Methods

Preoperative blood was collected from 173 patients treated for EC between 1999 and 2009. Serum concentrations of VEGF, urokinase plasminogen activator (uPA) tissue plasminogen activator (tPA), plasminogen activator inhibitor type-1 (PAI-1) and -2 (PAI-2) were assessed by enzyme-linked immunosorbent assays (ELISA).

Results

Serum levels of VEGF and components of the PAS were significantly associated with stage of the disease, tumor histology, tumor grade, myometrial invasion (MI), presence of lymphovascular space invasion (LVSI) and lymph node metastases (LNM). Preoperative serum levels of PAI-1 and -2 and tPA were higher in patients who experienced a recurrence than in patients who remained disease free (p < 0.01). PAI-1 and -2 and tPA were significantly independent prognostic factors for DFS with a HR of 3.85 (95% CI 1.84–8.07), 3.90 (95% CI 1.75–8.66) and 2.53 (95% CI 1.16–5.55), respectively. PAI-1 and tPA turned out to be independent prognostic factors for OS, with a HR of 2.09 (95% CI 1.08–4.05) and 2.16 (95% CI 1.06–4.44), respectively.

Conclusion

Serum levels of VEGF and components of the PAS at primary diagnosis were associated with well-known clinicopathological risk factors such as; FIGO stage, tumor histology, tumor grade, MI, LVSI and LNM. High concentrations of PAI-1 and-2 and tPA are independent factors for poor prognosis in patients with endometrial cancer.

Plasminogen activator inhibitor-1 in cancer research

[Despite as a major inhibitor of urokinase (uPA), paradoxically,] Plasminogen activator inhibitor-1 (PAI-1) has been validated to be highly expressed in various types of tumor biopsy tissues or plasma compared with controls based on huge clinical data bases analysis, more importantly, PAI-1 alone or in conjunction with uPA have been identified as prognostic for disease progression and relapse in certain cancer types. particularly in breast cancer. In addition to play important roles in cell adhesion, migration and invasion, PAI-1 has been reported to induce tumor vascularization and thus promote cell dissemination and tumor metastasis. Furthermore, there are many tumor promoting factors involved in the modulation of PAI-1 expression and activity, which will strengthen the pro-tumorigenic roles of PAI-1. Undoubtedly, PAI-1 may be a promising target for therapeutic intervention of specific cancer treatment. In fact, some PAI-1 inhibitors are currently being evaluated in cancer therapy, which may be developed to new antitumor agents in the future.

Serum Tumor Markers: Past, State of the Art, and Future

Serum determinations of tumor markers are indispensable in the diagnosis and management of cancer, and therefore play an important role in clinical practice. After a short historical survey, we systematically review a number of contemporary aspects of serum tumor markers related to various organ systems, and briefly indicate possible future developments.

Transforming Growth Factor β1 Stimulates Urokinase Plasminogen Activator System on Prostate Cancer Cells

The effect of TGFβ1 on the proliferation and plasminogen activator system (PA) of two prostate carcinoma cell lines, PC3 and DU145, was investigated. PA, particularly urokinase plasminogen activator (uPA), has been implicated in extracellular proteolysis, local invasiveness, metastatic spread and angiogenesis. High levels of uPA and plasminogen activator inhibitor-1 (PAI-1) correlate with poor prognosis in several cancers. TGFβ1 had no significant effect on the proliferation of either cell line. TGFβ1 increased the production of uPA in PC3 and DU145 cells. Despite the very low PAI-1 protein levels in both cell lines, TGFβ1 treatment resulted in a remarkable increase in PAI-1 secretion. PAI-2 protein was also increased by 59% in the PC3 cells. A divergent effect of TGFβ1 on the uPA enzyme activity was observed (28% decrease in PC3 and 131% increase in DU145 cells). Overall, TGFβ1 treatment did not affect the invasion of reconstituted basement membrane of PC3 cells. In addition to the uPA:PAI-1 ratio, the presence of PAI-2 may be an important factor in the determination of metastatic sites for prostate cancer cells. In conclusion, the potential contribution of TGFβ1 to tumor invasion may be considered as positive, based on both loss of growth inhibition and stimulation of components of the invasive system of prostate carcinoma.

The Effect of EGFR-Related Tyrosine Kinase Activity Inhibition on the Growth and Invasion Mechanisms of Prostate Carcinoma Cell Lines

Increased urokinase plasminogen activator (uPA) levels and epidermal growth factor receptor (EGFR)-related tyrosine kinase activity are associated with poor prognosis in several cancers. We studied the effect of epidermal growth factor (EGF) and a specific inhibitor of EGFR, ZM252868, on the growth and invasiveness of the prostate cancer cell lines PC3 and DU145. PC3 cell growth was stimulated by exogenous EGF but DU145 cell growth was not. EGFR-specific tyrosine kinase inhibitor significantly inhibited the growth of both cell types. EGF increased uPA protein level and uPA activity in both cell types. EGF stimulation also resulted in increased uPAR transcript in both cell lines. uPA production and activity were suppressed by the inhibitor to well below the levels in control cells. Matrigel invasion of PC3 cells was increased by EGF. ZM252868 also reversed the EGF-stimulated matrigel invasion by PC3 cells. Our results indicate that EGF is a potent stimulative agent for both growth and invasion in prostate cancer cells, and that targeting the EGFR function inhibits not only tumor growth but also invasiveness.

Prognostic impact of the inclusion of uPA/PAI-1 tumor levels in the current adjuvant treatment decision-making for early breast cancer

AIMS

Following the introduction of new adjuvant therapies we wanted to reappraise the prognostic and predictive value of uPA/PAI-1 in early breast cancer.

PATIENTS & METHODS

This monocentric retrospective study included 652 patients who had curative surgery between 2006 and 2011 and adjuvant treatment decision-making, taking into account uPA/PAI-1 tumor levels.

RESULTS

uPA and PAI-1 levels were associated with classical clinicopathological parameters and adjuvant chemotherapy decision, but not with peritumoral vascular invasion (PVI; also known as peritumoral vascular emboli). HER2 overexpression, PVI and uPA/PAI-1 levels were not significantly associated with relapse-free survival in univariate analysis. In multivariate analysis, T stage, N stage and progesterone receptors were the only independent relapse-free survival predictive factors.

CONCLUSION

The absence of an association between uPA/PAI-1 and PVI allows their concomitant consideration in adjuvant treatment discussion. The overall good prognosis of patients with high uPA/PAI-1 levels might be linked to the uPA/PAI-1 predictive value and the inclusion of these parameters in adjuvant guidelines.

Plasminogen activators are involved in angiostatin generation in vivo in benign and malignant ovarian tumor cyst fluids

In many tumor types, angiogenesis is the net result of pro- and anti-angiogenic mediators and correlated with metabolic activity, growth, and degree of malignancy. One of the first discovered anti-angiogenic compounds is angiostatin, a proteolytic fragment of plasminogen. The requirements for in vivo angiostatin generation have not yet been determined. We investigated the levels of plasminogen and angiostatin by western blotting and of components of the plasminogen activator complex by ELISA in cyst fluid derived from benign and malignant ovarian tumors. Fluid samples from functional ovarian follicles, dermoid cysts and endometriotic lesions were evaluated separately. When no or minimal amounts of plasminogen were present in the cyst fluids, angiostatin was generally absent as well, irrespective of plasminogen activator concentrations. When plasminogen was present, the degree of conversion of plasminogen to angiostatin was significantly correlated with the level of uPA, and, to a lesser extent, to the tPA level. However, angiostatin was also found in a number of cyst fluid samples with minimal or no plasminogen activators, suggesting the involvement of other angiostatin generating proteases in these samples. Conversely, no angiostatin was observed in a number of cyst fluid samples containing both plasminogen and plasminogen activators. The presence of an inhibitor of the enzymatic activity of uPA and/or tPA, like PAI-1, may explain this finding. Our data show that plasminogen activators are clearly involved in in vivo angiostatin formation in ovarian cysts. Most likely, however, other proteases, as well as inhibitors of plasminogen activators, are involved as well.

The tumor microenvironment in non-small-cell lung cancer

The tumor microenvironment (TME) of NSCLC is heterogeneous with variable blood flow through leaky immature vessels resulting in regions of acidosis and hypoxia. Hypoxia has been documented in NSCLC directly by polarographic needle electrodes and indirectly by assessing tissue and plasma hypoxia markers. In general, elevated expression of these markers portends poorer outcomes in NSCLC. Impaired vascularity and hypoxia can lead to increased metastasis and treatment resistance. Compounds that directly target hypoxic cells such as tirapazamine have been tested in clinical trials for NSCLC with mixed results. Preclinical data, however, suggest other ways of exploiting the abnormal TME in NSCLC for therapeutic gain. The inhibition of hypoxia-inducible factor-1alpha or vascular endothelial growth factor may increase local control after radiation. Inhibitors of the epidermal growth factor receptor (EGFR)/phosphatidylinositol 3-kinase (PI3K)/Akt pathway, such as erlotinib or PI-103, may "normalize" tumor vessels, allowing for increased chemotherapy delivery or improved oxygenation and radiation response. To select patients who may respond to these therapies and to evaluate the effects of these agents, a noninvasive means of imaging the TME is critical. Presently, there are several promising modalities to image hypoxia and the tumor vasculature; these include dynamic perfusion imaging and positron emission tomography scanning with radiolabled nitroimidazoles.

A human monoclonal antibody scFv to urokinase plasminogen activator

A human monoclonal antibody can be a good method for tumor diagnosis and treatment. This study is aimed at the generation of human antibody fragments against urokinase plasminogen activator (uPA) known to be related to tumor metastasis using the naive human antibody phage display library. Three clones--A2, A8, and E4--were selected from 1 x 10(10) sized human naïve antibody phage library using BIAcore rescue and screen. Clone A8 was finally selected by flow cytometry against Hep3 and HT1080, uPA overexpressing tumor cell lines. A8 clone consisted of 324 bp lambda and 402 bp heavy chains. The affinity (K(D)) of purified A8 antibody fragments was 1.44 x 10(-8) M(-1). The antibody fragment was reacted with HT1080 in a dose-dependent manner but not reacted with LS513 normal fibroblast. In this study, uPA specific human monoclonal antibody fragment A8 was made with BIAcore selection. Selected A8 was bound specifically to uPA expressed on the tumor cell surface. Further study for the application of A8 antibody clones will be needed.

Clinical biomarkers for hypoxia targeting

Tumor hypoxia or a reduction of the tissue oxygen tension is a key microenvironmental factor for tumor progression and treatment resistance in solid tumors. Because hypoxic tumor cells have been demonstrated to be more resistant to ionizing radiation, hypoxia has been a focus of laboratory and clinical research in radiation therapy for many decades. It is believed that proper detection of hypoxic regions would guide treatment options and ultimately improve tumor response. To date, most clinical efforts in targeting tumor hypoxia have yielded equivocal results due to the lack of appropriate patient selection. However, with improved understanding of the molecular pathways regulated by hypoxia and the discovery of novel hypoxia markers, the prospect of targeting hypoxia has become more tangible. This chapter will focus on the development of clinical biomarkers for hypoxia targeting.

The potential role of intrinsic hypoxia markers as prognostic variables in cancer

Tumor hypoxia is related to tumor progression and therapy resistance, which leads to poor patient outcome. It has been suggested that measuring the hypoxic status of a tumor helps to predict patient outcome and to select more targeted treatment. However, current methods using needle electrodes or exogenous markers have limitations due to their invasiveness or necessity for preinjection. Recent studies showed that hypoxia-regulated genes could be alternatively used as endogenous hypoxia markers. This is a review of 15 hypoxia-regulated genes, including hypoxia-inducible factor-1 and its targets, and their correlation with tumor hypoxia and patient outcome from 213 studies. Though most of the studies showed significance of these genes in predicting prognosis, there was no definitive prognostic and hypoxia marker. In conclusion, this review suggests the need for further studies with standardized methods to examine gene expression, as well as the use of multiple gene expressions.

Tissue detection of biomolecular predictors in breast cancer

One of the promises of modern biotechnology is to improve medical care by providing accurate diagnosis and targeted treatment to patients who will derive the maximum benefit. Delivery of this promise in the 21st century is the result of major advances in biotechnology over the past 20 years. Sequencing of the human genome and other high-volume data discovery has become possible, owing to relatively inexpensive computation power and automation. The same forces that drove the human genome project are now being focused on cataloging various disease processes at the DNA, RNA and protein levels. As these high-throughput technologies are entering the clinical care environment, the major task at hand is to integrate the complex data and derive clinically useful information. In spite of major breakthroughs in molecular approaches to the diagnosis and prognostication of cancer, there remain significant obstacles in applying these technologies to clinical samples. The time-honored conventional histopathology, for example, is still the backbone of tumor diagnosis and prognostication. The traditional fixation and processing methods are, however, rapidly losing ground, as they do not protect important tissue macromolecules. Formalin, the common universal fixative, is losing its place in histopathology. In addition to its toxicity, it alters macromolecules and renders the tissue unfit for most advanced molecular studies. This has prompted the use of fresh or fresh-frozen biopsy material for most biomolecular discoveries and clinical assays. This of course is impractical, or even impossible, in most clinical settings, particularly since tumors are being detected earlier and smaller. Also, many preneoplastic conditions are impossible to triage for freezing since their accurate diagnosis requires the use of the entire sample for detailed microscopic examination. The focus in this report is on breast cancer, where the value of the innovative approaches of the tissue detection of biomolecular predictors is examined. To this end, novel tissue handling platforms are introduced that are not only suitable for histological diagnosis, but allow the detection of tumor proteome and expression profiles on the same biopsy sample.

Protease Activity of Urokinase and Tumor Progression in a Syngeneic Mammary Cancer Model

BACKGROUND

We and others have previously shown that plasminogen activators generate endogenous angiogenesis inhibitors and induce antiangiogenic activity. Here we assessed the effects of plasminogen activator overexpression on tumor progression in a syngeneic mammary cancer model.

METHODS

Genes encoding murine tissue plasminogen activator (tPA), urokinase (uPA), and vector controls were stably transfected into 4T1 murine mammary cancer cells, and cell proliferation in vitro was analyzed. Cells were also implanted into female BALB/c mice (n = 12 per group), and tumor growth, lung metastases, and survival were compared. Tumor cell proliferation and microvessel formation were analyzed by immunohistochemistry using antibodies to proliferating cell nuclear antigen and CD31, respectively. 4T1 cells transfected with proteolytically inactive uPA mutants (A and B) were assayed for proliferation in vitro and tumor growth in vivo by using the same syngeneic model (eight to 10 mice per group). All statistical tests were two-sided.

RESULTS

In vitro growth of uPA- and tPA-overexpressing and control 4T1 cells was similar. In vivo, however, inhibition of tumor growth and lung metastasis were inhibited in the mice carrying tPA- and uPA-overexpressing tumors, compared with controls (tumor weight at day 34: control, mean = 1760 mg, 95% confidence interval [CI] = 1434 to 2087 mg; tPA, mean = 921, 95% CI = 624 to 1217 mg; P < .001; uPA, mean = 395 mg, 95% CI = 161 to 629 mg; P < .001; number of lung metastases at day 34: control, mean = 117, 95% CI = 74 to 159; tPA, mean = 33, 95% CI = 13 to 52; uPA, mean = 15, 95% CI = 4 to 25; P < .001). Median survival was 42 (95% CI = 36 to 44), 55 (95% CI = 48 to 61), and 73 (95% CI = 51 to 86) days in the control, tPA, and uPA groups, respectively (P < .001). uPA- and tPA-expressing tumors had reduced angiogenesis and cell proliferation compared with controls. Tumors overexpressing uPA mutants grew faster than tumors expressing wild-type uPA (tumor volume at day 30: wild-type uPA, mean = 203, 95% CI = 121 to 285 mm3; control, mean = 534, 95% CI = 460 to 608 mm3; P < .001; mutant A, mean = 600, 95% CI = 520 to 679 mm3; P < .001; and mutant B, mean = 435, 95% CI = 358.9 to 511 mm3; P = .005).

CONCLUSIONS

In this mouse model, uPA expression delayed tumor progression and had antiangiogenic and antiproliferative effects that may be mediated by uPA's protease activity. These results challenge the current dogma of proteases being exclusively tumor promoting and provide further rationale for exploring plasminogen activators as antitumor agents.

Parathyroid Hormone-related Protein Regulates Tumor-relevant Genes in Breast Cancer Cells

The effect of endogenous parathyroid hormone-related protein (PTHrP) on gene expression in breast cancer cells was studied. We suppressed PTHrP expression in MDA-MB-231 cells by RNA interference and analyzed changes in gene expression by microarray analysis. More than 200 genes showed altered expression in response to a PTHrP-specific small interfering (si) RNA (siPTHrP). Cell cycle-regulating gene CDC2 and genes (CDC25B and Tome-1) that control CDC2 activity showed increased expression in the presence of siPTHrP. CDC2 activity was also found to be higher in siPTHrP-treated cells. Studies with PTHrP peptides 1-34 and 67-86, forskolin, and a PTH1 receptor (PTH1R)-specific siRNA showed that PTHrP regulates CDC2 and CDC25B, at least in part, via PTH1R in a cAMP-independent manner. Other siPTHrP-responsive genes included integrin alpha6 (ITGA6), KISS-1, and PAI-1. When combined, siRNAs against ITGA6, PAI-1, and KISS-1 could mimic the negative effect of siPTHrP on migration, whereas siKISS-1 and siPTHrP similarly reduced the proliferative activity of the cells. Comparative expression analyses with 50 primary breast carcinomas revealed that the RNA level of ITGA6 correlates with that of PTHrP, and higher CDC2 and CDC25B values are found at low PTHrP expression. Our data suggest that PTHrP has a profound effect on gene expression in breast cancer cells and, as a consequence, contributes to the regulation of important cellular activities, such as migration and proliferation.

Targeting of urokinase plasminogen activator receptor in human pancreatic carcinoma cells inhibits c-Met- and insulin-like growth factor-I receptor-mediated migration and invasion and orthotopic tumor growth in mice

Pancreatic carcinomas express high levels of urokinase-type plasminogen activator (uPA) and its receptor (uPAR), both of which mediate cell migration and invasion. We investigated the hypotheses that (a) insulin-like growth factor-I (IGF-I)- and hepatocyte growth factor (HGF)-mediated migration and invasion of human pancreatic carcinoma cells require uPA and uPAR function and (b) inhibition of uPAR inhibits tumor growth, retroperitoneal invasion, and hepatic metastasis of human pancreatic carcinomas in mice. Using transwell assays, we investigated the effect of IGF-I and HGF on L3.6pl migration and invasion. We measured the induction of uPA and uPAR following treatment of cells with IGF-I and HGF using immunoprecipitation and Western blot analysis. The importance of uPA and uPAR on L3.6pl cell migration and invasion was studied by inhibiting their activities with amiloride and antibodies before cytokine treatment. In an orthotopic mouse model of human pancreatic carcinoma, we evaluated the effect of anti-uPAR monoclonal antibodies with and without gemcitabine on primary tumor growth, retroperitoneal invasion, and hepatic metastasis. IGF-I and HGF mediated cell migration and invasion in L3.6pl cells. In addition, IGF-I and HGF induced uPA and uPAR expression in L3.6pl cells. In vitro, blockade of uPA and uPAR activity inhibited IGF-I- and HGF-mediated cell migration and invasion. Treatment of mice with anti-uPAR monoclonal antibody significantly decreased pancreatic tumor growth and hepatic metastasis and completely inhibited retroperitoneal invasion. Our study shows the importance of the uPA/uPAR system in pancreatic carcinoma cell migration and invasion. These findings suggest that uPAR is a potential target for therapy in patients with pancreatic cancer.

Tissue-type plasminogen activator (tPA) in breast cancer: relationship with clinicopathological parameters and prognostic significance

BACKGROUND

Tissue-type plasminogen activator (tPA) is a serine protease primarily involved in the intravascular dissolution of blood clots. High intratumoral tPA levels are associated with prognosis in several human tumors. In addition, tPA has been shown to be an estrogen-inducible protein in human breast cancer cell lines. The aim of the present study was to analyze the cytosolic tPA content in primary breast carcinomas and its potential clinical value.

MATERIALS AND METHODS

tPA was measured by a solid-phase enzyme immunoassay in tumor cytosol samples obtained from 800 patients with breast cancer. The median follow-up period was of 49.2 months.

RESULTS

Cytosolic tPA levels ranged widely in breast carcinomas (median: 3.9; range: 0.1- 315.3 ng/mg protein). tPA levels were significantly lower in large tumors, as well as in those showing poor differentiation, estrogen (ER) or PgR-negativity, aneuploidy, or a high S-phase fraction. In addition, low tPA intratumoral levels were associated with a high probability of both shortened relapse-free and overall survival in all patients and in the subgroup with node-negative tumors. However, our results did not show any significant relationship between intratumoral tPA levels and prognosis in the different subgroups of patients, stratified according to the type of systemic adjuvant therapy received (chemotherapy, tamoxifen or chemotherapy plus sequential tamoxifen).

CONCLUSION

The results of the present investigation indicate that low intratumoral tPA levels are associated with aggressiveness and poor prognosis in breast cancer patients. However, the study suggests that tPA levels do not predict response to systemic adjuvant therapy.

Predictive impact of urokinase-type plasminogen activator: plasminogen activator inhibitor type-1 complex on the efficacy of adjuvant systemic therapy in primary breast cancer

One of the most thoroughly studied systems in relation to its prognostic relevance in patients with breast cancer, is the plasminogen activation system. This system comprises of, among others, the urokinase-type plasminogen activator (uPA) and its main inhibitor (PAI-1). In this study we investigated whether the uPA:PAI-1 complex is associated with the responsiveness of patients with primary breast cancer to adjuvant systemic therapy. Quantitative enzyme-linked immunosorbent assays were used to assess the levels of uPA, PAI-1, and uPA:PAI-1 complex in 1119 tumors of patients with primary invasive breast cancer. These patients were followed for a median follow-up time of 59 months (range, 2-267 months) after the primary diagnosis. Correlations with well-known clinicopathological factors, and univariate and multivariate survival analyses were performed. High uPA:PAI-1 complex levels were correlated with an adverse histological grade, and inversely associated with negative estrogen and progesterone receptor status. High tumor levels of uPA:PAI-1 complex predicted an early relapse in the univariate relapse-free survival analysis (P < 0.001). The multivariate analysis showed that high uPA:PAI-1 complex levels were associated with a decreased relapse-free survival time (P = 0.033), independently of age, tumor size, number of lymph nodes affected, progesterone receptor status, uPA, adjuvant endocrine, and chemotherapy. More important, it was demonstrated that there is a larger benefit from adjuvant chemotherapy for patients with higher versus lower tumor levels of uPA:PAI-1 complex. The results of this study imply that the expression of uPA:PAI-1 complex independently predicts the efficacy of adjuvant chemotherapy in patients with primary breast cancer.

Prognostic molecular markers in early breast cancer

A multitude of molecules involved in breast cancer biology have been studied as potential prognostic markers. In the present review we discuss the role of established molecular markers, as well as potential applications of emerging new technologies. Those molecules used routinely to make treatment decisions in patients with early-stage breast cancer include markers of proliferation (e.g. Ki-67), hormone receptors, and the human epidermal growth factor receptor 2. Tumor markers shown to have prognostic value but not used routinely include cyclin D1 and cyclin E, urokinase-like plasminogen activator/plasminogen activator inhibitor, and cathepsin D. The level of evidence for other molecular markers is lower, in part because most studies were retrospective and not adequately powered, making their findings unsuitable for choosing treatments for individual patients. Gene microarrays have been successfully used to classify breast cancers into subtypes with specific gene expression profiles and to evaluate prognosis. RT-PCR has also been used to evaluate expression of multiple genes in archival tissue. Proteomics technologies are in development.

High preoperative plasma concentration of tissue plasminogen activator (tPA) is an independent marker for shorter overall survival in patients with ovarian cancer

OBJECTIVE

The objective was to evaluate the preoperative blood concentration of tissue plasminogen activator (tPA) as a discriminator between malignant and benign ovarian tumors, and as a potential marker of postoperative prognosis in patients with ovarian cancer.

METHODS AND MATERIAL

The concentration of tPA was assayed with ELISA (Imulyse Biopool) in preoperative plasma samples obtained from 111 patients with adnexal lesions. Tumors were classified as benign (n = 25), borderline malignant (n = 11), well-differentiated (G1, n = 22), moderately differentiated (G2, n = 11), and poorly differentiated malignant (G3, n = 42). The median follow-up time of patients with malignant tumors was 5.6 years (range 2.1-13.2 years) and 37 patients died during the follow-up period.

RESULTS

Patients with moderately and poorly differentiated tumors had higher levels of plasma tPA compared to those with well-differentiated tumors (P = 0.004 and P = 0.005). No significant differences in the plasma tPA levels were observed between patients with benign, borderline, and well-differentiated tumors. The tPA levels were not different between stages nor within stage Ia-c. In a multivariate Cox proportional hazards model including stage, grade, age, and plasma tPA dichotomized at the median (> or =9 vs <9 ng/mL), high levels of tPA were significantly associated with shorter survival: HR = 4.4 (95% CI 2.0-9.8, P = 0.0003). In the univariate analyze high levels of tPA showed HR = 4.5 (95% CI 2.1-9.6, P = 0.0003).

CONCLUSIONS

High concentration of plasma tPA was an independent marker for poor prognosis in patients with ovarian cancer in our study. Plasma tPA did, however, not discriminate between benign and malignant adnexal lesions.

High tumor tissue concentration of urokinase plasminogen activator receptor is associated with good prognosis in patients with ovarian cancer

The urokinase plasminogen activator (uPA) system is involved in tumor growth and metastasis. We assayed the components of the uPA system in homogenates of 64 primary epithelial ovarian tumors and 5 metastases and evaluated the association of these parameters to prognosis in the 51 malignant cases. The levels of uPA, PAI-2 and the uPA:PAI-1 complex increased with progressive loss of histological differentiation (p(trend) <0.001, <0.05 and <0.001). The level of PAI-1 was higher in poorly than in well/moderately differentiated tumors (p = 0.03). The content of uPAR was lower in benign tumors as compared to borderline malignancies (p = 0.002), invasive primary tumors (p < 0.001), and metastases (p = 0.002). Surprisingly, the level of uPAR was lower in poorly differentiated as compared to both borderline (p = 0.01) and well differentiated malignant tumors (p = 0.005). Also, the level of uPAR was lower in advanced as compared to early stages of the disease (p(trend) = 0.002). The median follow-up time for patients was 5.8 years. High tumor tissue levels of uPAR were associated with longer postoperative survival (HR = 0.4, 95% CI = 0.2-0.8, p = 0.01). In contrast, shorter survival was evident in patients with high tumor levels of uPA from 2 years on after operation (HR = 4.6, 95% CI = 1.2-17, p = 0.02). High tPA levels tended to be associated with shorter overall survival after 2 years (HR = 2.9, 95% 95% CI = 0.9-9.8, p = 0.08). Although high tumor tissue content of uPAR was associated with a less aggressive phenotype characterized by well differentiated histology and longer survival, low content of uPAR in the poorly differentiated tumors and metastases presumably results from increased elimination of uPAR.

An ELISA avoiding interference by heterophilic antibodies in the measurement of components of the plasminogen activation system in blood

Endogenous heterophilic antibodies in blood are known to interfere with two-site enzyme-linked immunosorbent assays (ELISAs) evoking false positive signals. In the present study, we describe an assay for the assessment of components of the plasminogen activation system (uPA, tPA and PAI-1, and their complexes) in blood which is not susceptible to interference by heterophilic antibodies. In the ELISA format, two avian (duck, chicken) antibodies are employed in the pre-analyte and two mammalian (rabbit, goat) antibodies in the post-analyte stage. The assay is compared to our earlier reported ELISA for measuring uPA, tPA and PAI-1 components in tumor tissue extracts. Applying the so-called "nonsense formats", designed against non-existent components, to the NIBSC reference preparation of rheumatoid factor (RF), no response was found with the new assay, whereas a clear RF dose-dependent interfering signal was observed with the original assay designed for tumor tissue extracts. Analysis of tumor-tissue based international reference preparations (RBG EORTC 101094 and 040297), human anti-mouse antibodies (HAMA) containing sera, and sera from patients with rheumatoid arthritis (RA), also displayed no false positive signals. In conclusion, we have developed an ELISA that permits the determination of blood levels of components in the urokinase system, free from disturbance by endogenous heterophilic antibodies.

Molecular prognostic factors for breast cancer metastasis and survival

The biological characteristics of the tumor are used to estimate prognosis and select appropriate systemic therapy for patients with early-stage breast cancer. Well-established molecular prognostic factors include the estrogen and progesterone receptors, proliferation markers, and the HER2 gene. Novel tumor markers with potential clinical utility include molecules involved in cell transformation, invasion, and metastases. We review the available data supporting the utility of established prognostic and predictive molecular factors, and discuss challenges for integrating novel molecular markers into clinical practice.

Prognostic significance of tissue-type plasminogen activator (tPA) content in gastric cancer and surrounding mucosa

AIMS

We analyzed the tPA content in primary gastric carcinomas and surrounding mucosa in order to assess the relationship between tPA content, clinicopathological tumor characteristics, and estrogen and progesterone receptor content. We evaluated the prognostic value of this serine protease in gastric cancer patients.

PATIENTS AND METHODS

122 resected gastric neoplasms and 95 adjacent mucosa samples were studied. The tPA content was measured in cytosol by an ELISA method. Cytosolic ER and PgR were measured with a solid phase enzyme immunoassay.

RESULTS

Cytosolic tPA levels in neoplastic tissues (median 1.0 ng/mg prot) were significantly lower (p=0.002) than those found in paired mucosa samples (median 2.3 ng/mg prot). There was no significant association between tPA levels and clinicopathological parameters or PgR content, but tPA levels were significantly correlated with ER content. The intermediate-tPA-content group, corresponding to samples with between 0.3 and 1.70 ng/mg protein, proved to have a significantly high risk of relapse.

CONCLUSIONS

We found a wide variability in tPA levels in gastric carcinoma and adjacent mucosa samples, with significantly decreased levels in tumors and a significantly positive relationship between tPA levels and ER status. There was a non-monotonic relationship between tPA levels and prognosis in patients with gastric cancer.

Issues and barriers to development of clinically useful tumor markers: a development pathway proposal

There are few tumor markers that are clinically useful in predicting therapeutic responses or patient outcomes despite nearly 20 years of advances in molecular biology. We discuss a variety of issues and barriers that have affected movement of clinical tests from research into clinical practice. Studies of new markers frequently lack clear hypotheses and are generally underpowered to reach statistically valid conclusions. Relevant clinical endpoints may not be possible to evaluate, often leading to suboptimal study designs. Major stumbling blocks exist because studies are rarely comparable. This makes it difficult to determine why results vary from study to study. It also prevents pooling of small datasets for analysis. We propose a tumor marker development pathway that we think will be more efficient and effective. The pathway depends on developing statistically valid study designs, focusing on assay refinement and standardization early in the process, including assay details in publications, and providing data in a format that allows comparison with other studies. The process described should be applicable to development of new technologies that include analysis and interpretation of large, complex datasets. The proposed marker development pathway will require thoughtful refinement and expansion, but it should begin a productive dialog.

Prognostic impact of urokinase-type plasminogen activator receptor (uPAR) in cytosols and pellet extracts derived from primary breast tumours

Using a previously developed enzyme-linked immunosorbent assay (ELISA), the levels of the receptor for urokinase-type plasminogen activator (uPAR) were determined in cytosols and corresponding membrane pellets derived from 878 primary breast tumours. The levels of uPAR in the pellet extracts were more than 3-fold higher than those measured in the cytosols (P< 0.001). Moreover, the uPAR levels in the two types of extracts were weakly, though significantly, correlated with each other (rS= 0.20, P< 0.001). In Cox univariate analysis, high cytosolic levels of uPAR were significantly associated with reduced overall survival (OS) and relapse-free survival (RFS). The levels of uPAR in pellet extracts appeared not to be related with patient survival. In multivariate analysis, elevated levels of uPAR measured in cytosols and pellet extracts were found to be independent predictors of poor OS, not RFS. The prediction of poor prognosis on the basis of high uPAR levels emphasizes its important role in plasmin-mediated degradation of extracellular matrix proteins during cancer invasion and metastasis.

Dedifferentiation of serous ovarian cancer from cystic to solid tumors is associated with increased expression of mRNA for urokinase plasminogen activator (uPA), its receptor (uPAR) and its inhibitor (PAI-1)

The plasminogen activating system is involved in tumor growth and metastasis by degradation of extracellular matrix, and modulation of cell adhesion and migration. Benign and well-differentiated malignant ovarian tumors present as cystic lesions with preserved glandular morphology, whereas poorly differentiated tumors and metastases are solid with characteristic absence of glandular morphology. We analyzed the mRNAs for urokinase plasminogen activator (uPA), its receptor (uPAR), and inhibitor (PAI-1) in serous ovarian tumors by in situ hybridization and by densitometric scanning of Northern blots prepared from tissue extracts. The mRNA expressing cells in the in situ hybridization sections were evaluated and counted by two different observers. The number of mRNA expressing cells for uPA, uPAR and PAI-1 were all significantly increased in solid as compared with cystic malignant tumors. The increased expression of all three mRNA species was mainly located in the stroma of poorly differentiated tumors and metastases. Apart from being expressed in the stroma of these tumors, uPAR mRNA was also expressed by tumor cells located along the stromal/epithelial boarder. In addition, the tumor tissue content of uPA, uPAR and PAI-1 mRNAs as measured by Northern blots were higher in the solid as compared with the cystic tumors. Increased expression of uPA, uPAR and PAI-1 genes in the solid tumors suggest a correlation with a more aggressive phenotype.

Functional Evaluation of Plasmin Formation in Primary Breast Cancer

PURPOSE: Plasmin generation is controlled by the plasminogen activators (PA)/plasmin system, which comprises proteases (urokinase-type PA [uPA] and tissue-type PA [tPA]) and antiproteases (PA inhibitors, PAI-1 and PAI-2). The tumoral content of uPA and PAI-1 has been shown to carry prognostic value in breast cancer; however, because most assays used so far have relied on immunometric determinations, we have explored the enzymatic activities governing plasmin formation in breast cancer specimens.

PATIENTS AND METHODS: We applied semiquantitative histochemical zymography to 201 primary breast cancer tissue sections. Enzymatic activities were correlated with histopathologic parameters and clinical outcome. The median follow-up was 91 months.

RESULTS: A wide range of PA-mediated catalytic activities was detected. The overall survival was significantly worse for patients with tumors showing tPA in the lowest quartile of activity (P = .003). The 5-year overall survival of patients with tPA activity in the lowest quartile was 58% compared with 81% for patients with tPA value in the other three quartiles. Tumor size, axillary lymph node metastasis, histologic grade, lymphovascular infiltration, TP53 mutation, and tPA activity were all major risk factors in univariate analysis. tPA activity was an independent prognostic factor in a multivariate Cox regression model, both in the whole population (relative risk = 0.5, 95% confidence interval, 0.3 to 0.9; P = .02) and in the node-negative subgroup (relative risk = 0.2, 95% confidence interval, 0.08 to 0.6; P = .004).

CONCLUSION: By using a zymographic assay performed directly on primary tumor tissue sections, we demonstrate that reduced tPA-mediated plasmin production is an independent adverse prognostic factor in breast cancer.

Immunohistochemical expression of uPA, uPAR, and PAI-1 in breast carcinoma. Fibroblastic expression has strong associations with tumor pathology

The urokinase-type plasminogen activator (uPA) system has been implicated in tumor spread. We have used immunohistochemistry to examine three components of this system, ie, uPA, uPA receptor (uPAR), and plasminogen activator inhibitor-1 (PAI-1), in a pilot study on 142 cases of breast carcinoma. We wished to determine whether there were any relationships between expression of the proteins in either tumor cells or fibroblasts and clinical and pathological features. Strong uPA expression in each cell type was significantly related to high tumor grade (P = 0.013 and 0.008, respectively), and was more common in invasive than in in situ carcinomas (P < 0.0001). Fibroblastic expression of uPAR was only related to the presence of invasion (P < 0.0001). Strong PAI-1 expression in both cell types was seen in high-grade tumors (tumor cells, P = 0.012; fibroblasts, P < 0.001), but only fibroblastic expression was related to the presence of invasion (P = 0.042). Fibroblastic expression of both uPA and uPAR were positively correlated with tumor size. Although patients with strong fibroblastic expression of uPA showed a tendency toward a shorter time to relapse, none of the plasminogen activator proteins were significantly associated with relapse-free survival. These results suggest that strong expression of uPA, uPAR, and PAI-1 in fibroblasts rather than in tumor cells have the most impact on the clinical behavior of breast cancer. Larger prospective studies are needed to confirm these findings.

Prognostic value of tissue-type plasminogen activator (tPA) and its complex with the type-1 inhibitor (PAI-1) in breast cancer

The prognostic value of tissue-type plasminogen activator (tPA) measured in samples derived from 865 patients with primary breast cancer using a recently developed enzyme-linked immunosorbent assay (ELISA) was evaluated. Since the assay could easily be adapted to the assessment of the complex of tPA with its type-1 inhibitor (PAI-1), it was investigated whether the tPA:PAI-1 complex also provides prognostic information. To this end, cytosolic extracts and corresponding detergent extracts of 100,000 g pellets obtained after ultracentrifugation when preparing the cytosolic fractions for routine steroid hormone receptor determination were assayed. Statistically significant correlations were found between the cytosolic levels and those determined in the pellet extracts (Spearman correlation coefficient r(s) = 0.75, P < 0.001 for tPA and r = 0.50, P < 0.001 for tPA:PAI-1 complex). In both Cox univariate and multivariate analysis elevated levels of (total) tPA determined in the pellet extracts, but not in cytosols, were associated with prolonged relapse-free (RFS) and overall survival (OS). In contrast, high levels of the tPA:PAI-1 complex measured in cytosols, but not in the pellet extracts, were associated with a poor RFS and OS. The prognostic information provided by the cytosolic tPA:PAI-1 complex was comparable to that provided by cytosolic (total) PAI-1. Furthermore, the estimated levels of free, uncomplexed tPA and PAI-1, in cytosols and in pellet extracts, were related to patient prognosis in a similar way as the (total) levels of tPA and PAI-1 respectively. Determination of specific forms of components of the plasminogen activation system, i.e. tPA:PAI-1 complex and free, uncomplexed tPA and/or PAI-1, may be considered a useful adjunct to the analyses of the separate components (tPA and/or PAI-1) and provide valuable additional prognostic information with respect to survival of breast cancer patients.