Soluble urokinase plasminogen activator receptor as a prognostic marker in men participating in prostate cancer screening

Soluble Urokinase Plasminogen Activator Receptor (suPAR) as a Biomarker of Systemic Chronic Inflammation

Systemic chronic inflammation (SCI) is persistent, health-damaging, low-grade inflammation that plays a major role in immunosenescence and in development and progression of many diseases. But currently, there are no recognized standard biomarkers to assess SCI levels alone, and SCI is typically measured by combining biomarkers of acute inflammation and infection, e.g., CRP, IL-6, and TNFα. In this review, we highlight 10 properties and characteristics that are shared by the blood protein soluble urokinase plasminogen activator receptor (suPAR) and SCI, supporting the argument that suPAR is a biomarker of SCI: (1) Expression and release of suPAR is upregulated by immune activation; (2) uPAR and suPAR exert pro-inflammatory functions; (3) suPAR is associated with the amount of circulating immune cells; (4) Blood suPAR levels correlate with the levels of established inflammatory biomarkers; (5) suPAR is minimally affected by acute changes and short-term influences, in contrast to many currently used markers of systemic inflammation; (6) Like SCI, suPAR is non-specifically associated with multiple diseases; (7) suPAR and SCI both predict morbidity and mortality; (8) suPAR and SCI share the same risk factors; (9) suPAR is associated with risk factors and outcomes of inflammation above and beyond other inflammatory biomarkers; (10) The suPAR level can be reduced by anti-inflammatory interventions and treatment of disease. Assessing SCI has the potential to inform risk for morbidity and mortality. Blood suPAR is a newer biomarker which may, in fact, be a biomarker of SCI since it is stably associated with inflammation and immune activation; shares the same risk factors as many age-related diseases; is both elevated by and predicts age-related diseases. There is strong evidence that suPAR is a prognostic marker of adverse events, morbidity, and mortality. It is associated with immune activity and prognosis across diverse conditions, including kidney disease, cardiovascular disease, cancer, diabetes, and inflammatory disorders. Thus, we think it likely represents a common underlying disease-process shared by many diseases; that is, SCI. We review the supporting literature and propose a research agenda that can help test the hypothesis that suPAR indexes SCI, with the potential of becoming the new gold standard for measuring SCI.

Use of a Recombinant Biomarker Protein DDA Library Increases DIA Coverage of Low Abundance Plasma Proteins

Credible detection and quantification of low abundance proteins from human blood plasma is a major challenge in precision medicine biomarker discovery when using mass spectrometry (MS). In this proof-of-concept study, we employed a mixture of selected recombinant proteins in DDA libraries to subsequently identify (not quantify) cancer-associated low abundance plasma proteins using SWATH/DIA. The exemplar DDA recombinant protein spectral library (rPSL) was derived from tryptic digestion of 36 recombinant human proteins that had been previously implicated as possible cancer biomarkers from both our own and other studies. The rPSL was then used to identify proteins from nondepleted colorectal cancer (CRC) EDTA plasmas by SWATH-MS. Most (32/36) of the proteins used in the rPSL were reliably identified from CRC plasma samples, including 8 proteins (i.e., BTC, CXCL10, IL1B, IL6, ITGB6, TGFα, TNF, TP53) not previously detected using high-stringency protein inference MS according to PeptideAtlas. The rPSL SWATH-MS protocol was compared to DDA-MS using MARS-depleted and postdigestion peptide fractionated plasmas (here referred to as a human plasma DDA library). Of the 32 proteins identified using rPSL SWATH, only 12 could be identified using DDA-MS. The 20 additional proteins exclusively identified using the rPSL SWATH approach were almost exclusively lower abundance (i.e., <10 ng/mL) proteins. To mitigate justified FDR concerns, and to replicate a more typical library creation approach, the DDA rPSL library was merged with a human plasma DDA library and SWATH identification repeated using such a merged library. The majority (33/36) of the low abundance plasma proteins added from the rPSL were still able to be identified using such a merged library when high-stringency HPP Guidelines v3.0 protein inference criteria were applied to our data set. The MS data set has been deposited to ProteomeXchange Consortium via the PRIDE partner repository (PXD022361).

Urokinase receptor deficiency results in EGFR-mediated failure to transmit signals for cell survival and neurite formation in mouse neuroblastoma cells

Urokinase-type plasminogen activator uPA and its receptor (uPAR) are the central players in extracellular matrix proteolysis, which facilitates cancer invasion and metastasis. EGFR is one of the important components of uPAR interactome. uPAR/EGFR interaction controls signaling pathways that regulate cell survival, proliferation and migration. We have previously established that uPA binding to uPAR stimulates neurite elongation in neuroblastoma cells, while blocking uPA/uPAR interaction induces neurite branching and new neurite formation. Here we demonstrate that blocking the uPA binding to uPAR with anti-uPAR antibody decreases the level of pEGFR and its downstream pERK1/2, but does increase phosphorylation of Akt, p38 and c-Src Since long-term uPAR blocking results in a severe DNA damage, accompanied by PARP-1 proteolysis and Neuro2a cell death, we surmise that Akt, p38 and c-Src activation transmits a pro-apoptotic signal, rather than a survival. Serum deprivation resulting in enhanced neuritogenesis is accompanied by an upregulated uPAR mRNA expression, while EGFR mRNA remains unchanged. EGFR activation by EGF stimulates neurite growth only in uPAR-overexpressing cells but not in control or uPAR-deficient cells. In addition, AG1478-mediated inhibition of EGFR activity impedes neurite growth in control and uPAR-deficient cells, but not in uPAR-overexpressing cells. Altogether these data implicate uPAR as an important regulator of EGFR and ERK1/2 signaling, representing a novel mechanism which implicates urokinase system in neuroblastoma cell survival and differentiation.

Prognostic effects of SuPAR and Neopterin Levels on Patients with Lung Cancer

Background: Two unique biomarkers, soluble form of the urokinase-type plasminogen activator receptor (suPAR) and neopterin, play a crucial role in inflammatory processes. This study aimed to reveal whether it is possible to utilize these biomarkers in predicting tumor prognosis in patients with lung cancers.

Methods: The present study was designed as a single center, prospective, and controlled research. The study was conducted with forty patients with lung cancer (case group) and 41 healthy individuals (control group) in Kırıkkale University, Faculty of Medicine between 2016-2020. The case group was also divided into two of the early and advanced stages. The blood samples were drawn to evaluate suPAR and neopterin levels, and these parameters were compared between the case and control groups. Also, the prognostic effects of age, stage of the tumor, and the levels of mentioned parameters were investigated with the survival analysis.

Results: The median duration of the follow-up was 32 (4-75) months. suPAR and neopterin levels were found to be higher in the case group than in the control group. Cox regression showed that the high levels of neopterin and suPAR increased mortality risk [p=0.002, HR: 1.25 (1.08-1.45 95%CI) and p=0.023, HR:1.07 (1.01-1.13), respectively]. Finally, age and stage of the tumor were found to have no relationship with survival.

Conclusion: suPAR and neopterin as members of the inflammatory pathway were found to be higher in cancer cases. Furthermore, both suPAR and neopterin levels were found to be predictive for the mortality of patients with lung cancers; therefore, they are thought to be used for the management of cancer.

Designing tracers for PET imaging of the urokinase-type plasminogen activator receptor from a cyclic uPA-derived peptide: first in vitro evaluations

The treatment of cancer remains a major challenge, especially after tumour cell dissemination and metastases formation. Expression of the urokinase-type plasminogen activation system including urokinase (uPA) and its receptor (uPAR) has been associated with the complex process of cell migration, a tumour's invasive potential as well as a reduced overall and disease-free survival of patients with solid cancers and haematological disorders. A cyclic peptide cyclo[21,29][d-Cys²¹ ,Cys²⁹ ]-uPA_21-30 was designed from the growth factor-like domain (GFD) of urokinase whose binding to uPAR was found to inhibit tumour growth and spread of human ovarian cancer cells in mice. With the aim of visualising uPAR expression using PET imaging to attempt an estimate on the tumour's aggressiveness, the cyclic peptide was modified with an either C- or N-terminally attached variable spacer and chelator. The free ligands were evaluated for their binding affinities to the isolated human uPAR and labelled with ⁶⁸ Ga and ¹⁷⁷ Lu to assess their lipophilicities and stabilities in human serum. Although retaining the full binding potential displayed by cyclo[21,29][d-Cys²¹ ,Cys²⁹ ]-uPA_21-30 to its target was found to be a challenging task upon both C- and N-terminal modification, chelator-bearing ligands were identified that can serve as promising starting points in the development of uPAR-addressing PET tracers.

Multifaceted Role of the Urokinase-Type Plasminogen Activator (uPA) and Its Receptor (uPAR): Diagnostic, Prognostic, and Therapeutic Applications

The plasminogen activator (PA) system is an extracellular proteolytic enzyme system associated with various physiological and pathophysiological processes. A large body of evidence support that among the various components of the PA system, urokinase-type plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitor-1 and -2 (PAI-1 and PAI-2) play a major role in tumor progression and metastasis. The binding of uPA with uPAR is instrumental for the activation of plasminogen to plasmin, which in turn initiates a series of proteolytic cascade to degrade the components of the extracellular matrix, and thereby, cause tumor cell migration from the primary site of origin to a distant secondary organ. The components of the PA system show altered expression patterns in several common malignancies, which have identified them as ideal diagnostic, prognostic, and therapeutic targets to reduce cancer-associated morbidity and mortality. This review summarizes the various components of the PA system and focuses on the role of uPA-uPAR in different biological processes especially in the context of malignancy. We also discuss the current state of knowledge of uPA-uPAR-targeted diagnostic and therapeutic strategies for various malignancies.

The urokinase-type plasminogen activator system and its role in tumor progression

In the multistage process of carcinogenesis, the key link in the growth and progression of the tumor is the invasion of malignant cells into normal tissue and their distribution and the degree of destruction of tissues. The most important role in the development of these processes is played by the system of urokinase-type plasminogen activator (uPA system), which consists of several components: serine proteinase – uPA, its receptor – uPAR and its two endogenous inhibitors – PAI-1 and PAI-2. The components of the uPA system are expressed by cancer cells to a greater extent than normal tissue cells. uPA converts plasminogen into broad spectrum, polyfunctional protease plasmin, which, in addition to the regulation of fibrinolysis, can hydrolyze a number of components of the connective tissue matrix (СTM), as well as activate the zymogens of secreted matrix metalloproteinases (MMР) – pro-MMР. MMРs together can hydrolyze all the main components of the СTM, and thus play a key role in the development of invasive processes, as well as to perform regulatory functions by activating and releasing from STM a number of biologically active molecules that are involved in the regulation of the main processes of carcinogenesis. The uPA system promotes tumor progression not only through the proteolytic cascade, but also through uPAR, PAI-1 and PAI-2, which are involved in both the regulation of uPA/uPAR activity and are involved in proliferation, apoptosis, chemotaxis, adhesion, migration and activation of epithelial-mesenchymal transition pathways. All of the above processes are aimed at regulating invasion, metastasis and angiogenesis. The components of the uPA system are used as prognostic and diagnostic markers of many cancers, as well as serve as targets for anticancer therapy.

Biomarkers to Predict Cardiovascular Death

This article reviews biomarkers that have been shown to identify subjects at increased risk for cardiovascular death within the general population, in those with established coronary artery disease, and in those with heart failure. Use of biomarkers for risk stratification for sudden cardiac death continues to evolve. It seems that a multimarker strategy for risk stratification using simple measures of circulating proteins and usual clinical risk factors, particularly in patients with known coronary artery disease, can be used to identify patients at near-term risk of death. Whether similar strategies in the general population will prove to be cost-effective needs to be investigated.

Pathway-Specific Aggregate Biomarker Risk Score Is Associated With Burden of Coronary Artery Disease and Predicts Near-Term Risk of Myocardial Infarction and Death

BACKGROUND

Inflammation, coagulation, and cell stress contribute to atherosclerosis and its adverse events. A biomarker risk score (BRS) based on the circulating levels of biomarkers C-reactive protein, fibrin degradation products, and heat shock protein-70 representing these 3 pathways was a strong predictor of future outcomes. We investigated whether soluble urokinase plasminogen activator receptor (suPAR), a marker of immune activation, is predictive of outcomes independent of the aforementioned markers and whether its addition to a 3-BRS improves risk reclassification.

METHODS AND RESULTS

C-reactive protein, fibrin degradation product, heat shock protein-70, and suPAR were measured in 3278 patients undergoing coronary angiography. The BRS was calculated by counting the number of biomarkers above a cutoff determined using the Youden's index. Survival analyses were performed using models adjusted for traditional risk factors. A high suPAR level ≥3.5 ng/mL was associated with all-cause death and myocardial infarction (hazard ratio, 1.83; 95% confidence interval, 1.43-2.35) after adjustment for risk factors, C-reactive protein, fibrin degradation product, and heat shock protein-70. Addition of suPAR to the 3-BRS significantly improved the C statistic, integrated discrimination improvement, and net reclassification index for the primary outcome. A BRS of 1, 2, 3, or 4 was associated with a 1.81-, 2.59-, 6.17-, and 8.80-fold increase, respectively, in the risk of death and myocardial infarction. The 4-BRS was also associated with severity of coronary artery disease and composite end points.

CONCLUSIONS

SuPAR is independently predictive of adverse outcomes, and its addition to a 3-BRS comprising C-reactive protein, fibrin degradation product, and heat shock protein-70 improved risk reclassification. The clinical utility of using a 4-BRS for risk prediction and management of patients with coronary artery disease warrants further study.

Plasma levels of intact and cleaved urokinase plasminogen activator receptor (uPAR) in men with clinically localised prostate cancer

AIMS

Lymph node metastasis (N1) is an adverse prognostic factor for men with clinically localised prostate cancer (PCa), but the prediction of N1 disease remains difficult. Urokinase plasminogen activator receptor (uPAR) plays an important role in angiogenesis and tumorigenesis. We analysed whether plasma levels of the soluble uPAR forms uPAR(I-III), uPAR(II-III) and uPAR(I) were associated with the risk of N1 disease in men with clinically localised PCa.

METHODS

The present study includes all men (n=518) who underwent radical prostatectomy (RP) for clinically localised PCa, 29 of whom had N1 disease. Soluble uPAR forms were measured using three time-resolved fluorescence immunoassays. The prognostic value of the different uPAR forms together with clinicopathological parameters for N1 disease were analysed using logistic regression, receiver operating characteristic (ROC) regression analysis and quantified using the areas under the ROC curve (AUC).

RESULTS

All soluble uPAR levels were significantly (p=0.03) higher in patients with N1 disease compared with patients with N0/x disease. ROC curves including clinical tumour stage, biopsy Gleason score, prostate-specific antigen and percent positive biopsies had an AUC of 87.7% for prediction of N1 disease. With the addition of uPAR(I) to the model, the AUC increased to 88.4%.

CONCLUSIONS

Addition of uPAR(I) level to known diagnostic parameters did not increase the prediction of N1 disease following RP in men with clinically localised PCa. Our results indicate that the plasma levels at diagnosis of the different uPAR forms do not hold important predictive or prognostic information in men with clinically localised PCa.

Soluble urokinase-type plasminogen activator receptor and urokinase-type plasminogen activator receptor contribute to chemoresistance in leukemia

The soluble urokinase-type plasminogen activator receptor (suPAR) and the urokinase-type plasminogen activator receptor (uPAR) have been proposed as useful biomarkers of tumor progression. Recently, suPAR was associated with chemoresistance in lung cancer. However, its clinical significance in leukemia has not previously been investigated. The present study examined the plasma levels of suPAR and the expression of the uPAR on bone marrow (BM) cells in 86 patients with leukemia at diagnosis prior to chemotherapy and 26 normal subjects (control group). The plasma suPAR levels were measured using ELISA, whilst uPAR expression was assayed by flow cytometry analysis. In addition, cell surface uPAR expression on K562 and multidrug-resistant K562/ADM cell lines was studied by western blotting. On admission and follow-up, the levels of suPAR in patients with leukemia were significantly increased compared with controls. Systemic levels of suPAR were strongly associated with the numbers of white blood cells. A case was defined as uPAR-positive (uPAR+) if >20% of the gated cells expressed uPAR. In comparison with 26 healthy BM samples that were negative for uPAR expression, 48 (55.8%) of the 86 leukemia patients were uPAR+. uPAR expression on the cell surface of multidrug-resistant K562/ADM cells was increased compared with that on K562 cells. In conclusion, plasma suPAR expression may be a useful marker for subtype classification of patients with leukemia and cell surface uPAR may be associated with resistance to chemotherapy or disease progression.

Imaging of Prostate Cancer Using Urokinase-Type Plasminogen Activator Receptor PET

Urokinase-type plasminogen activator receptor (uPAR) overexpression is an important biomarker for aggressiveness in cancer including prostate cancer (PC) and provides independent clinical information in addition to prostate-specific antigen and Gleason score. This article focuses on uPAR PET as a new diagnostic and prognostic imaging biomarker in PC. Many preclinical uPAR-targeted PET imaging studies using AE105 in cancer models have been undertaken with promising results. A major breakthrough was obtained with the recent human translation of uPAR PET in using ⁶⁴Cu- and ⁶⁸Ga-labelled versions of AE105, respectively. Clinical results from patients with PC included in these studies are encouraging and support continuation with large-scale clinical trials.

Urokinase-type plasminogen activator receptor promotes proliferation and invasion with reduced cisplatin sensitivity in malignant mesothelioma

Malignant mesothelioma (MM) is a rare neoplasm associated with asbestos exposure. The prognosis of MM is poor because it is aggressive and highly resistant to chemotherapy. Using a rat model of asbestos-induced MM, we found elevated urokinase-type plasminogen activator receptor (uPAR; Plaur) expression in rat tissues, which was associated with poor prognosis. The proliferation, migration and invasion of MM cells were suppressed by uPAR knockdown and increased by overexpression experiments, irrespective of urokinase-type plasminogen activator (uPA; Plau) levels. More importantly, we found that uPAR expression is associated with sensitivity to cisplatin in MM through the PI3K/AKT pathway, which was demonstrated with specific inhibitors, LY294002 and Akti-1/2. uPAR knockdown significantly increased sensitivity to cisplatin whereas its overexpression significantly decreased cisplatin sensitivity. Furthermore, sera and tissues from MM patients showed significantly high uPAR levels, which suggested the pathogenic role of uPAR in the tumor biology of human MM. In conclusion, our findings indicate that uPAR levels are associated with malignant characteristics and cisplatin sensitivity of MM. In addition to the potential use of uPAR as a prognostic marker, the combination of uPAR abrogation and cisplatin may reveal a promising therapeutic approach for MM.

PET imaging of urokinase-type plasminogen activator receptor (uPAR) in prostate cancer: current status and future perspectives

Overexpression of urokinase-type plasminogen activator receptors (uPAR) represents an important biomarker for aggressiveness in most common malignant diseases, including prostate cancer (PC). Accordingly, uPAR expression either assessed directly in malignant PC tissue or assessed directly in plasma (intact/cleaved forms)—provides independent additional clinical information to that contributed by PSA, Gleason score, and other relevant pathological and clinical parameters. In this respect, non-invasive molecular imaging by positron emission tomography (PET) offers a very attractive technology platform, which can provide the required quantitative information on the uPAR expression profile, without the need for invasive procedures and the risk of missing the target due to tumor heterogeneity. These observations support non-invasive PET imaging of uPAR in PC as a clinically relevant diagnostic and prognostic imaging method. In this review, we will focus on the recent development of uPAR PET and the relevance within prostate cancer imaging. Novel antibody and small-molecule radiotracers-targeting uPAR, including a series of uPAR-targeting PET ligands, based on the high affinity peptide ligand AE105, have been synthesized and tested in vitro and in vivo in preclinical murine xenograft models and, recently, in a first-ever clinical uPAR PET study in cancer patients, including patients with PC. In this phase I study, a high and specific uptake of the tracer ⁶⁴Cu-DOTA-AE105 was found in both primary tumors and lymph node metastases. The results are encouraging and support large-scale clinical trials to determine the utility of uPAR PET in the management of patients with PC with the goal of improving outcome.

Copenhagen uPAR prostate cancer (CuPCa) database: protocol and early results

AIM

Urokinase plasminogen activator receptor (uPAR) plays a central role during cancer invasion by facilitating pericellular proteolysis. We initiated the prospective 'Copenhagen uPAR Prostate Cancer' study to investigate the significance of uPAR levels in prostate cancer (PCa) patients.

METHODS

Plasma samples and clinical data from patients with newly diagnosed PCa have been collected prospectively. The uPAR forms have been measured in plasma using time-resolved fluorescence immunoassays.

RESULTS

The level of intact uPAR(I-III) did not differ. Plasma uPAR(I-III) + uPAR(II-III) levels and uPAR(I) levels were significantly higher in hormone-naive and castrate-resistant patients compared with patients with localized disease (both: p < 0.0001).

CONCLUSION

Our results show that cleaved uPAR forms are significantly increased in patients with advanced PCa.

Soluble urokinase plasminogen activator receptor level is an independent predictor of the presence and severity of coronary artery disease and of future adverse events

Introduction

Soluble urokinase plasminogen activator receptor (suPAR) is an emerging inflammatory and immune biomarker. Whether suPAR level predicts the presence and the severity of coronary artery disease (CAD), and of incident death and myocardial infarction (MI) in subjects with suspected CAD, is unknown.

Methods and Results

We measured plasma suPAR levels in 3367 subjects (67% with CAD) recruited in the Emory Cardiovascular Biobank and followed them for adverse cardiovascular (CV) outcomes of death and MI over a mean 2.1±1.1 years. Presence of angiographic CAD (≥50% stenosis in ≥1 coronary artery) and its severity were quantitated using the Gensini score. Cox's proportional hazard survival and discrimination analyses were performed with models adjusted for established CV risk factors and C‐reactive protein levels. Elevated suPAR levels were independently associated with the presence of CAD (P<0.0001) and its severity (P<0.0001). A plasma suPAR level ≥3.5 ng/mL (cutoff by Youden's index) predicted future risk of MI (hazard ratio [HR]=3.2; P<0.0001), cardiac death (HR=2.62; P<0.0001), and the combined endpoint of death and MI (HR=1.9; P<0.0001), even after adjustment of covariates. The C‐statistic for a model based on traditional risk factors was improved from 0.72 to 0.74 (P=0.008) with the addition of suPAR.

Conclusion

Elevated levels of plasma suPAR are associated with the presence and severity of CAD and are independent predictors of death and MI in patients with suspected or known CAD.

uPAR targeted radionuclide therapy with (177)Lu-DOTA-AE105 inhibits dissemination of metastatic prostate cancer

The urokinase-type plasminogen activator receptor (uPAR) is implicated in cancer invasion and metastatic development in prostate cancer and provides therefore an attractive molecular target for both imaging and therapy. In this study, we provide the first in vivo data on an antimetastatic effect of uPAR radionuclide targeted therapy in such lesions and show the potential of uPAR positron emission tomography (PET) imaging for identifying small foci of metastatic cells in a mouse model of disseminating human prostate cancer. Two radiolabeled ligands were generated in high purity and specific activity: a uPAR-targeting probe ((177)Lu-DOTA-AE105) and a nonbinding control ((177)Lu-DOTA-AE105mut). Both uPAR flow cytometry and ELISA confirmed high expression levels of the target uPAR in PC-3M-LUC2.luc cells, and cell binding studies using (177)Lu-DOTA-AE105 resulted in a specific binding with an IC50 value of 100 nM in a competitive binding experiment. In vivo, uPAR targeted radionuclide therapy significantly reduced the number of metastatic lesions in the disseminated metastatic prostate cancer model, when compared to vehicle and nontargeted (177)Lu groups (p < 0.05) using bioluminescence imaging. Moreover, we found a significantly longer metastatic-free survival, with 65% of all mice without any disseminated metastatic lesions present at 65 days after first treatment dose (p = 0.047). In contrast, only 30% of all mice in the combined control groups treated with (177)Lu-DOTA-AE105mut or vehicle were without metastatic lesions. No treatment-induced toxicity was observed during the study as evaluated by observing animal weight and H&E staining of kidney tissue (dose-limiting organ). Finally, uPAR PET imaging using (64)Cu-DOTA-AE105 detected all small, disseminated metastatic foci when compared with bioluminescence imaging in a cohort of animals during the treatment study. In conclusion, uPAR targeted radiotherapy resulted in a significant reduction in the number of metastatic lesions in a human metastatic prostate cancer model. Furthermore, we have provided the first evidence of the potential for identification of small metastatic lesions using uPAR PET imaging in disseminated prostate cancer, illustrating the promising strategy of uPAR theranostics in prostate cancer.

Expression of uPAR in tumor-associated stromal cells is associated with colorectal cancer patient prognosis: a TMA study

Background

The receptor for urokinase-type plasminogen activator (uPAR) is associated with cancer development and progression. Within the tumor microenvironment uPAR is expressed by malignant cells as well as tumor-associated stromal cells. However, the contribution of uPAR expression in these stromal cells to malignancy and patient survival in colorectal cancer is still unclear. This study compares the association of uPAR expression in both colorectal tumor-associated stromal cells and neoplastic cells with clinico-pathological characteristics and patient survival using tissue micro arrays (TMA).

Methods

Immunohistochemical staining of uPAR expression was performed on tumor tissue from 262 colorectal cancer patients. Kaplan-Meier, log rank, and uni- and multivariate Cox’s regression analyses were used to calculate associations between uPAR expression and patient survival.

Results

In the colorectal tumor-associated stromal microenvironment, uPAR is expressed in macrophages, (neoangiogenic) endothelial cells and myofibroblasts. uPAR expression in tumor-associated stromal cells and neoplastic cells (and both combined) were negatively associated with overall survival (OS) and Disease Free Survival (DFS). Uni- and multivariate Cox’s regression analysis for combined uPAR expression in tumor-associated stromal and neoplastic cells showed significant and independent negative associations with OS and DFS. Only uPAR expression in tumor-associated stromal cells showed independent significance in the uni- and multivariate analysis for DFS.

Conclusion

This study demonstrates a significant independent negative association between colorectal cancer patient survival and uPAR expression in especially tumor-associated stromal cells.

Involvement of urokinase-type plasminogen activator system in cancer: an overview

Currently, there are several studies supporting the role of urokinase-type plasminogen activator (uPA) system in cancer. The association of uPA to its receptor triggers the conversion of plasminogen into plasmin. This process is regulated by the uPA inhibitors (PAI-1 and PAI-2). Plasmin promotes degradation of basement membrane and extracellular matrix (ECM) components as well as activation of ECM latent matrix metalloproteases. Degradation and remodeling of the surrounding tissues is crucial in the early steps of tumor progression by facilitating expansion of the tumor mass, release of tumor growth factors, activation of cytokines as well as induction of tumor cell proliferation, migration, and invasion. Hence, many tumors showed a correlation between uPA system component levels and tumor aggressiveness and survival. Therefore, this review summarizes the structure of the uPA system, its contribution to cancer progression, and the clinical relevance of uPA family members in cancer diagnosis. In addition, the review evaluates the significance of uPA system in the development of cancer-targeted therapies.

Prostate cancer biomarkers: an update

Many aspects of prostate cancer diagnosis and treatment could be greatly advanced with new, effective biomarkers. Prostate-specific antigen (PSA) has multiple weaknesses as a biomarker, such as not distinguishing well between cancer and benign prostatic hyperplasia or between indolent and aggressive cancers, thus leading to overtreatment, especially unnecessary biopsies. PSA also often fails to indicate accurately which patients are responding to a given treatment. Yet PSA is the only prostate cancer biomarker routinely used by urologists. Here, we provide updated information on the most relevant of the other biomarkers currently in use or in development for prostate cancer. Recent research shows improvement over using PSA alone by comparing total PSA (tPSA) or free PSA (fPSA) with new, related markers, such as prostate cancer antigen (PCA) 3, the individual molecular forms of PSA (proPSA, benign PSA, and intact PSA), and kallikreins other than PSA. Promising results have also been seen with the use of the fusion gene TMPRSS2:ERG and with various forms of the urokinase plasminogen activation receptor. Initially, there were high hopes for early PCA, but those data were not reproducible and thus research on early PCA has been abandoned. Much work remains to be done before any of these biomarkers are fully validated and accepted. Currently, the only markers discussed in this paper with Food and Drug Administration-approved tests are PCA 3 and an isoform of proPSA, [-2]proPSA. Assays are in development for most of the other biomarkers described in this paper. While the biomarker validation process can be long and filled with obstacles, the rewards will be great-in terms of both patient care and costs to the health care system.

Diagnostic and prognostic significance of CA IX and suPAR in gastric cancer

This study was intended to evaluate the prognostic and diagnostic significance of carbonic anhydrase IX (CA IX) and soluble urokinase plasminogen activator receptor (suPAR) levels in gastric cancer patients. CA IX and suPAR were analyzed from serum and plasma samples of gastric cancer patients. Fifty patients and 34 controls were enrolled. CA IX and suPAR levels were statistically significantly higher in the patient group (patient; 182.5 ± 212.4, control; 47.3 ± 32, P = 0.0001 and patient; 5.74 ± 5.3, control; 2.27 ± 0.77, P = 0.0001, respectively). CA IX and suPAR levels were higher in metastatic subjects (metastatic; 227.1 ± 273.5, non-metastatic; 147.4 ± 144.1, P > 0.05). Prognosis was worse in the patient group with elevated suPAR. CA IX and especially suPAR are correlated with the presence and stage of the disease. High suPAR levels indicate a poorer prognosis in gastric cancer patients.

Usefulness of soluble urokinase plasminogen activator receptor to predict repeat myocardial infarction and mortality in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous intervention

The plasma level of the inflammatory biomarker soluble urokinase plasminogen activator receptor (suPAR) is an independent predictor of cardiovascular disease and all-cause mortality in healthy subjects. The prognostic capability of suPAR, its temporal course, and its relation to plasma C-reactive protein (CRP) in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous intervention (PCI) is unknown. Therefore, the plasma suPAR and CRP levels were measured in 296 consecutive patients with ST-segment elevation myocardial infarction admitted for primary PCI at baseline and every 6 to 8 hours thereafter until the cardiac biomarker levels had peaked. The end points were all-cause mortality and fatal or nonfatal recurrent myocardial infarction (MI). During a median follow-up period of 5.75 years, 69 deaths and 48 nonfatal and 14 fatal recurrent MIs occurred. All-cause mortality increased significantly from 8.1% to 41.5% across increasing quartiles of suPAR levels at the end of follow-up (log-rank p <0.0001). After adjustment for other independent prognostic factors, a highly significant increase was seen in all-cause mortality (hazard ratio 1.45, 95% confidence interval, 1.19 to 1.76; p <0.001) and recurrent MI (hazard ratio 1.53, 95% confidence interval 1.16 to 2.01; p <0.01) for each standard deviation increment of suPAR levels). In contrast to plasma CRP, the suPAR levels remained stable after primary PCI. Furthermore, CRP did not predict mortality or reinfarction after adjustment for age and gender (p = 0.34). In conclusion, suPAR is a stable plasma biomarker after ST-segment elevation myocardial infarction treated with primary PCI that predicts all-cause mortality and recurrent MI.

Soluble urokinase plasminogen activator receptor is associated with inflammation in the vulnerable human atherosclerotic plaque

BACKGROUND AND PURPOSE

Recently, plasma soluble urokinase plasminogen activator receptor (suPAR) has gained interest as a marker of cardiovascular risk. suPAR is released through the cleavage of urokinase plasminogen activator receptor (uPAR), which is found in monocytes, activated T-lymphocytes and endothelial cells, all involved in atherosclerosis. suPAR levels have been well studied in plasma, but no studies have focused on suPAR in human atherosclerotic plaques. The aim of this study was to determine whether suPAR measured in the plaque is associated with symptomatic plaques and plaque inflammation.

METHODS

Plasma and carotid plaques from 162 patients were analyzed. Lipids, collagen, uPAR, and macrophages were measured histologically. Cytokines and suPAR were measured in homogenized plaque extracts using multiplex immunoassay and ELISA, respectively. Plasma levels of suPAR were analysed with ELISA. CD3, CD4, as well as uPAR mRNA expression were assessed with quantitative real-time polymerase chain reaction in plaque homogenates from 123 patients.

RESULTS

Plaque and plasma suPAR levels were higher in symptomatic patients compared with asymptomatic patients. Plaque suPAR levels correlated with plaque content of lipids and macrophages and with proinflammatory chemokines and cytokines monocyte chemoattractant protein 1, tumor necrosis factor α, interleukin 1β, interleukin 6, platelet-derived growth factor AB/BB, monocyte inflammatory protein 1β, regulated on activation normal T-cell expressed and secreted, and s-CD40L. uPAR mRNA and histological staining for uPAR correlated with plaque content of suPAR.

CONCLUSIONS

This study shows that suPAR in human carotid plaques and plasma is associated with the presence of symptoms and that plaque suPAR is associated with the vulnerable inflammatory plaque. These findings strengthen the hypothesis of suPAR as a future marker of vulnerable atherosclerotic plaques.