Association of tissue mRNA and serum antigen levels of members of the urokinase-type plasminogen activator system with clinical and prognostic parameters in prostate cancer

Explication of the roles of prostate health index (PHI) and urokinase plasminogen activator (uPA) as diagnostic and predictor tools for prostate cancer in equivocal PSA range of 4-10 ng/mL

Background

Prostate cancer (PCa) is one of the most commonly encountered cancers and the leading cause of death worldwide. Currently used biomarkers accounts difficulties in discriminating benign from malignant cases or predicting outcome, so investigating new biomarkers performance is needed.

Objectives

Assessment of diagnostic and predictor roles of prostate health index (PHI) and urokinase plasminogen activator (uPA) in PCa.

Methods

194 males with initial tPSA of 4-10 ng/mL were categorized into three groups: PCa, benign prostatic hyperplasia (BPH) and healthy control. Serum levels of tPSA, fPSA, p2PSA, and uPA were performed by ELISA with calculation of PHI as (p2PSA/fPSA) × √PSA.

Results

PHI and uPA were significantly higher in PCa patients relevant to BPH and healthy control (p ≤ 0.001). Both markers outperformed all assessed biomarkers and showed the highest area under the curve (AUC) in ROC curve analysis. Both were significantly higher in PCa patients with {Gleason score ≥ 7, late stages (cT2b,c; T3), LN extension and distant metastasis}relative to their counterparts. Additionally, PHI and uPA and were independent predictors of distant metastasis and Gleason score ≥ 7, while PHI was predictor of LN invasion (β = 0.25, p = 0.004).

Conclusion

PHI and uPA would be of potential value in discriminating between PCa, BPH and healthy men in addition, both are promising as independent predictors of adverse pathological features.

Determination of urokinase-type plasminogen activator serum levels in healthy and oncologic cats

The urokinase plasminogen activator system (uPAS) has been poorly investigated in veterinary oncology. The aim of this study was to determine uPA serum concentrations in healthy and oncologic cats to understand the potential value of uPA as a cancer biomarker. Serum samples were collected from 19 healthy cats and 18 cats with spontaneous malignant neoplasms and uPA was measured through a specific enzyme-linked immunosorbent assay kit. The differences between uPA values and their relation with intrinsic factors and clinicopathological parameters were analyzed using an analysis of variance (ANOVA) and independent t-test. The average serum concentration of uPA in cancerous cats (0.54 ± 0.22 ng/mL) differed from that of healthy cats (1.10 ± 1.16 ng/mL) but was not significantly influenced by cats' clinicopathological parameters or by the presence of metastases. This study describes, for the first time, the serum concentrations of uPA in cats and proposes directions for future studies to uncover the relevance of uPAS in feline carcinogenesis.

Exploring the MIR143-UPAR Axis for the Inhibition of Human Prostate Cancer Cells In Vitro and In Vivo

MIR143 is pathologically downregulated and may function as a tumor suppressor in prostate cancer. Likewise, the urokinase plasminogen activator receptor (UPAR) is overexpressed in prostate carcinoma, representing a negative prognostic marker and putative therapeutic target gene. In this paper, we establish UPAR as a new direct target of MIR143. Luciferase reporter gene constructs identify one of the two in silico-predicted binding sites as functionally relevant for direct MIR143 binding to the 3′ UTR, and, concomitantly, transfection of MIR143 reduces UPAR protein levels in prostate carcinoma cells in vitro. Inhibitory effects on cell proliferation and colony formation, spheroid growth and integrity, and cell viability are extensively analyzed, and they are compared to direct small interfering RNA (siRNA)-mediated uPAR knockdown or combined microRNA (miRNA)-siRNA treatment. Switching to a therapeutically more relevant in vivo model, we demonstrate tumor-inhibitory effects of MIR143 replacement therapy by systemic treatment of mice bearing subcutaneous PC-3 tumor xenografts with MIR143 formulated in polymeric nanoparticles. This efficient, nanoparticle-mediated delivery of intact MIR143 mediates the marked downregulation of uPAR protein, but not mRNA levels, thus indicating translational inhibition rather than mRNA degradation. In summary, we identify UPAR as a direct target gene of MIR143, and we establish the therapeutic anti-tumor potential of nanoparticle-based MIR143 replacement in prostate cancer.

The prognostic relevance of urokinase-type plasminogen activator (uPA) in the blood of patients with metastatic breast cancer

In breast cancer (BC), elevated levels of urokinase-type plasminogen activator (uPA) in tumor tissue have been confirmed as a strong prognostic factor in level-of-evidence-1 studies. The aim of the present study was to evaluate the clinical relevance of uPA levels in serum of metastatic BC patients and to compare uPA with other blood-based biomarkers. 252 patients were enrolled in this prospective, multicentre study. Blood samples were collected before begin of first-line or later-line systemic treatment. Serum uPA was quantified by a commercially available ELISA. Circulating tumor cells (CTCs) were detected using CellSearch; other biomarkers (EGFR, VEGF, HER2, RAS p21, TIMP1, CAIX) by ELISA. Using the ROC analysis, the optimal cut-off value (determined by the Youden index) of serum uPA was 2.52 ng/ml. Using this value, 26% of patients had elevated uPA levels. Patients with visceral metastasis and more than one metastatic site were significantly more likely to present with elevated uPA levels. CTC status, serum HER2, RAS p21, CAIX, TIMP1 and VEGF correlated significantly with uPA levels. Elevated uPA levels predicted shorter overall and progression-free survival in univariate analysis (median OS: 7.5 months [95%-CI 4.5–10.5 months] vs. not reached, p < 0.001; PFS: 4.8 [95%-CI: 3.1–6.5] vs. 9.1 [7.4–10.8] months, p < 0.001). In multivariate analysis, elevated uPA, presence of ≥5 CTCs, elevated RAS p21, higher grading and higher line of therapy were independent predictors of shorter OS, while elevated CTC counts, higher line of therapy and negative estrogen receptor status were independent predictors of shorter PFS. In conclusion, elevated uPA levels independently predict reduced overall survival and improved prognostication in patients with known CTC status. Whether high serum uPA might identify patients most likely to benefit from therapies targeting uPA, remains to be evaluated in future trials.

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.

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.

Isothiocyanate-Functionalized Bifunctional Chelates and fac-[M(I)(CO)3](+) (M = Re, (99m)Tc) Complexes for Targeting uPAR in Prostate Cancer

Developing new strategies to rapidly incorporate the fac-[M(I)(CO)3](+) (M = Re, (99m)Tc) core into biological targeting vectors in radiopharmaceuticals continues to expand as molecules become more complex and as efforts to minimize nonspecific binding increase. This work examines a novel isothiocyanate-functionalized bifunctional chelate based on 2,2'-dipicolylamine (DPA) specifically designed for complexing the fac-[M(I)(CO)3](+) core. Two strategies (postlabeling and prelabeling) were explored using the isothiocyanate-functionalized DPA to determine the effectiveness of assembly on the overall yield and purity of the complex with amine containing biomolecules. A model amino acid (lysine) examined (1) amine conjugation of isothiocyanate-functionalized DPA followed by complexation with fac-[M(I)(CO)3](+) (postlabeling) and (2) complexation of fac-[M(I)(CO)3](+) with isothiocyanate-functionalized DPA followed by amine conjugation (prelabeling). Conducted with stable Re and radioactive (99m)Tc analogs, both strategies formed the product in good to excellent yields under macroscopic and radiotracer concentrations. A synthetic peptide (AE105) which targets an emerging biomarker in CaP prognosis, urokinase-type plasminogen activator receptor (uPAR), was also explored using the isothiocyanate-functionalized DPA strategy. In vitro PC-3 (uPAR+) cell uptake assays with the (99m)Tc-labeled peptide (8a) showed 4.2 ± 0.5% uptake at 4 h. In a murine model bearing PC-3 tumor xenografts, in vivo biodistribution of 8a led to favorable tumor uptake (3.7 ± 0.7% ID/g) at 4 h p.i. with relatively low accumulation (<2% ID/g) in normal organs not associated with normal peptide excretion. These results illustrate the promise of the isothiocyanate-functionalized approach for labeling amine containing biological targeting vectors with fac-[M(I)(CO)3](+).

The combined serum levels of miR-375 and urokinase plasminogen activator receptor are suggested as diagnostic and prognostic biomarkers in prostate cancer

This study aimed to assess the applicability of miR-375 in combination with the soluble urokinase plasminogen activator receptor (suPAR) protein as a diagnostic and/or prognostic biomarker for prostate cancer (PCa) patients. miR-375 levels by qRT-PCR and suPAR levels by ELISA were evaluated in serum samples from 146 PCa patients, 35 benign prostate hyperplasia (BPH) patients and 18 healthy controls. Antigen levels of suPAR differed between healthy controls and PCa or BPH patients, whereas miR-375 levels differed between PCa and BPH patients or healthy controls (p < 0.001). Additionally, suPAR levels differed between the Gleason sum groups GS = 7 versus GS > 7, with higher levels in the latter group (p = 0.011), and miR-375 levels were higher in the tumor stage group T3-T4 compared with the T1-T2 group (p = 0.039). A high concentration of suPAR was associated with a poor disease-specific survival (DSS; p = 0.039). The combination of suPAR and miR-375 levels identified a patient group possessing high levels for both parameters. This was associated with a poorer 10-year overall survival (OS) and DSS, with a 6.38-fold increased risk of death and a 7.68-fold increased risk of tumor-related death (p = 0.00026 and p = 0.014; univariate Cox's regression analysis). In a multivariate Cox's regression analysis PCa patients with high levels of suPAR and miR-375 showed a 5.72-fold increased risk of death in OS (p = 0.006). In summary, the differences between the PCa/BPH/healthy control cohorts for either suPAR and miR-375 levels in conjunction with the association of combined high suPAR/miR-375 levels with a poor prognosis suggest a diagnostic and prognostic impact for PCa patients.