Role of urokinase receptor in tumor progression and development

Impact of Lipid-lowering Therapy on Cancer Risk: A Narrative Review

PURPOSE

There are inconsistent reports of an association between low cholesterol, use of lipid-lowering agents, and carcinogenesis. The purpose of this paper was to examine the relationship between cancer, lipids, statin use, and use of other lipid-lowering therapies.

METHODS

This comprehensive literature review incorporated article searches in electronic databases (Embase, PubMed, OVID) and reference lists of relevant articles, with the authors' expertise in lipidology. This review considered seminal and novel research looking at the relationship between cholesterol, lipid-lowering therapies, and cancer.

FINDINGS

Statin use has been reported to reduce the risk for incident cancer or progression of cancer; however, it is unknown whether this reduced risk of carcinogenesis is due to the pleotropic properties of statins or the effects of low cholesterol. The effect of ezetimibe on carcinogenesis has been regarded as neutral, despite earlier concerns of increased cancer risk with its use. Proprotein convertase subtilisin/kexin (PCSK)-9 monoclonal antibodies have been shown to have a neutral effect on carcinogenesis. Despite anti-cancer effects of fibrates in vitro, studies in humans have yielded inconsistent outcomes leaning toward protection against the development and progression of cancer.

IMPLICATIONS

Statins, fibrates, PCSK9 monoclonal antibodies, and ezetimibe have a neutral effect on cancer risk, and the first three may provide some protection. PSCK9 monoclonal antibodies have the potential to enhance the response to checkpoint inhibitor therapy for cancer. Further research is needed to determine which drugs can be issued in adjuvant therapy to improve outcomes in patients undergoing cancer treatment.

A Microfluidics-Assisted Double-Barreled Nanobioconjugate Synthesis Introducing Aprotinin as a New Moonlight Nanocarrier Protein: Tested toward Physiologically Relevant 3D-Spheroid Models

Proteins are promising substances for introducing new drug carriers with efficient blood circulation due to low possibilities of clearance by macrophages. However, such natural biopolymers have highly sophisticated molecular structures, preventing them from being assembled into nanoplatforms with manipulable payload release profiles. Here, we report a novel anticancer nanodrug carrier moonlighting protein, Aprotinin, to be used as a newly identified carrier for cytotoxic drugs. The Aprotinin-Doxorubicin (Apr-Dox) nanobioconjugate was prepared via a single-step microfluidics coflow mixing technique, a feasible and simple way to synthesize a carrier-based drug design with a double-barreled approach that can release and actuate two therapeutic agents simultaneously, i.e., Apr-Dox in 1:11 ratio (the antimetastatic carrier drug aprotinin and the chemotherapeutic drug DOX). With a significant stimuli-sensitive (i.e., pH) drug release ability, this nanobioconjugate achieves superior bioperformances, including high cellular uptake, efficient tumor penetration, and accumulation into the acidic tumor microenvironment, besides inhibiting further tumor growth by halting the urokinase plasminogen activator (uPA) involved in metastasis and tumor progression. Distinctly, in healthy human umbilical vein endothelial (HUVEC) cells, drastically lower cellular uptake of nanobioconjugates has been observed and validated compared to the anticancer agent Dox. Our findings demonstrate an enhanced cellular internalization of nanobioconjugates toward breast cancer, prostate cancer, and lung cancer both in vitro and in physiologically relevant biological 3D-spheroid models. Consequently, the designed nanobioconjugate shows a high potential for targeted drug delivery via a natural and biocompatible moonlighting protein, thus opening a new avenue for proving aprotinin in cancer therapy as both an antimetastatic and a drug-carrying agent.

Combined Antitumor Effect of the Serine Protease Urokinase Inhibitor Upamostat and the Sphingosine Kinase 2 Inhibitor Opaganib on Cholangiocarcinoma Patient-Derived Xenografts

Upamostat is an orally available small-molecule serine protease inhibitor that is a highly potent inhibitor of trypsin 1, trypsin 2, trypsin 3 (PRSS1/2/3), and the urokinase-type plasminogen activator (uPA). These enzymes are expressed in many cancers, especially during tissue remodeling and subsequent tumor cell invasion. Opaganib (ABC294640), a novel, orally available small molecule is a selective inhibitor of the phosphorylation of sphingosine to sphingosine-1-phosphate (S-1-P) by sphingosine kinase 2 (SPHK2). Both sphingosine kinase 1 (SPHK1) and SPHK2 are known to regulate the proliferation-inducing compound S-1-P. However, SPHK2 is more critical in cancer pathogenesis. The goal of this project was to investigate the potential antitumor effects of upamostat and opaganib, individually and in combination, on cholangiocarcinoma (CCA) xenografts in nude mice. PAX165, a patient-derived xenograft (PDX) from a surgically resected CCA, expresses substantial levels of SPHK2, PRSS1, PRSS2, and PRSS3. Four groups of 18 mice each were treated with upamostat, opaganib, both, or vehicle. Mouse weights and PAX165 tumor volumes were measured. Tumor volumes in the upamostat, opaganib, and upamostat plus opaganib groups were significantly decreased compared to the control group.

Circulating miR-10b, soluble urokinase-type plasminogen activator receptor, and plasminogen activator inhibitor-1 as predictors of non-small cell lung cancer progression and treatment response

BACKGROUND

Despite advances in lung cancer treatment, most lung cancers are diagnosed at an advanced stage. Expression of microRNA10b (miR-10b) and fibrinolytic activity, as reflected by soluble urokinase-type plasminogen activator receptor (suPAR) and plasminogen activator inhibitor 1 (PAI-1), are promising biomarker candidates.

OBJECTIVE

To assess the expression of miR-10b, and serum levels of suPAR and PAI-1 in advanced stage non-small cell lung cancer (NSCLC) patients, and their correlation with progression, treatment response and prognosis.

METHODS

The present prospective cohort and survival study was conducted at Dharmais National Cancer Hospital and included advanced stage NSCLC patients diagnosed between March 2015 and September 2016. Expression of miR-10b was quantified using qRT-PCR. Levels of suPAR and PAI-1 were assayed using ELISA. Treatment response was evaluated using the RECIST 1.1 criteria. Patients were followed up until death or at least 1 year after treatment.

RESULTS

Among the 40 patients enrolled, 25 completed at least four cycles of chemotherapy and 15 patients died during treatment. Absolute miR-10b expression ⩾ 592,145 copies/μL or miR-10b fold change ⩾ 0.066 were protective for progressive disease and poor treatment response, whereas suPAR levels ⩾ 4,237 pg/mL was a risk factor for progressive disease and poor response. PAI-1 levels > 4.6 ng/mL was a protective factor for poor response. Multivariate analysis revealed suPAR as an independent risk factor for progression (ORa⁢d⁢j, 13.265; 95% confidence intervals (CI), 2.26577.701; P= 0.006) and poor response (ORa⁢d⁢j, 15.609; 95% CI, 2.221-109.704; P= 0.006), whereas PAI-1 was an independent protective factor of poor response (ORa⁢d⁢j, 0.127; 95% CI, 0.019-0.843; P= 0.033).

CONCLUSIONS

Since miR-10b cannot be used as an independent risk factor for NSCLC progression and treatment response, we developed a model to predict progression using suPAR levels and treatment response using suPAR and PAI-1 levels. Further studies are needed to validate this model.

Urokinase-Type Plasminogen Activator Receptor (uPAR) Expression and [64Cu]Cu-DOTA-AE105 uPAR-PET/CT in Patient-Derived Xenograft Models of Oral Squamous Cell Carcinoma

PURPOSE

[64Cu]Cu-DOTA-AE105 urokinase-type plasminogen activator receptor (uPAR)-PET/CT is a novel and promising imaging modality for cancer visualization, although it has not been tested in head and neck cancer patients nor in preclinical models that closely resemble these heterogenous tumors, i.e., patient-derived xenograft (PDX) models. The aim of the present study was to establish and validate oral squamous cell carcinoma (OSCC) PDX models and to evaluate [64Cu]Cu-uPAR-PET/CT for tumor imaging in these models.

PROCEDURES

PDX flank tumor models were established by engrafting tumor tissue from three patients with locally advanced OSCC into immunodeficient mice. [64Cu]Cu-DOTA-AE105 was injected in passage 2 (P2) mice, and [64Cu]Cu-uPAR-PET/CT was performed 1 h and 24 h after injection. After the last PET scan, all animals were euthanized, and tumors dissected for autoradiography and immunohistochemical (IHC) staining.

RESULTS

Three PDX models were established, and all of them showed histological stability and unchanged heterogenicity, uPAR expression, and Ki67 expression through passages. A significant correlation between uPAR expression and tumor growth was found. All tumors of all models (n=29) showed tumor uptake of [64Cu]Cu-DOTA-AE105. There was a clear visual concordance between the distribution of uPAR expression (IHC) and [64Cu]Cu-DOTA-AE105 uptake pattern in tumor tissue (autoradiography). No significant correlation was found between IHC (H-score) and PET-signal (SUVmax) (r=0.34; p=0.07).

CONCLUSIONS

OSCC PDX models in early passages histologically mimic donor tumors and could serve as a valuable platform for the development of uPAR-targeted imaging and therapeutic modalities. Furthermore, [64Cu]Cu-uPAR-PET/CT showed target- and tumor-specific uptake in OSCC PDX models demonstrating the diagnostic potential of this modality for OSCC patients.

Smart nanoparticles for cancer therapy

Smart nanoparticles, which can respond to biological cues or be guided by them, are emerging as a promising drug delivery platform for precise cancer treatment. The field of oncology, nanotechnology, and biomedicine has witnessed rapid progress, leading to innovative developments in smart nanoparticles for safer and more effective cancer therapy. In this review, we will highlight recent advancements in smart nanoparticles, including polymeric nanoparticles, dendrimers, micelles, liposomes, protein nanoparticles, cell membrane nanoparticles, mesoporous silica nanoparticles, gold nanoparticles, iron oxide nanoparticles, quantum dots, carbon nanotubes, black phosphorus, MOF nanoparticles, and others. We will focus on their classification, structures, synthesis, and intelligent features. These smart nanoparticles possess the ability to respond to various external and internal stimuli, such as enzymes, pH, temperature, optics, and magnetism, making them intelligent systems. Additionally, this review will explore the latest studies on tumor targeting by functionalizing the surfaces of smart nanoparticles with tumor-specific ligands like antibodies, peptides, transferrin, and folic acid. We will also summarize different types of drug delivery options, including small molecules, peptides, proteins, nucleic acids, and even living cells, for their potential use in cancer therapy. While the potential of smart nanoparticles is promising, we will also acknowledge the challenges and clinical prospects associated with their use. Finally, we will propose a blueprint that involves the use of artificial intelligence-powered nanoparticles in cancer treatment applications. By harnessing the potential of smart nanoparticles, this review aims to usher in a new era of precise and personalized cancer therapy, providing patients with individualized treatment options.

Diagnostic Value of Preoperative uPAR-PET/CT in Regional Lymph Node Staging of Oral and Oropharyngeal Squamous Cell Carcinoma: A Prospective Phase II Trial

The detection of lymph node metastases is a major challenge in oral and oropharyngeal squamous cell carcinoma (OSCC and OPSCC). 68Ga-NOTA-AE105 is a novel positron emission tomography (PET) radioligand with high affinity to urokinase-type plasminogen activator receptor (uPAR), a receptor expressed on the surfaces of tumor cells. The aim of this study was to investigate the diagnostic value of uPAR-PET/CT (computerized tomography) in detecting regional metastatic disease in patients with OSCC and OPSCC compared to the current imaging work-up. In this phase II trial, patients with OSCC and OPSCC referred for surgical treatment were prospectively enrolled. Before surgery, 68Ga-NOTA-AE105 uPAR-PET/CT was conducted, and SUVmax values were obtained from the primary tumor and the suspected lymph nodes. Histology results from lymph nodes were used as the standard of truth of metastatic disease. The diagnostic values of 68Ga-uPAR-PET/CT were compared to conventional routine preoperative imaging results (CT and/or MRI). The uPAR expression in resected primary tumors and metastases was determined by immunohistochemistry and quantified digitally (H-score). A total of 61 patients underwent uPAR-PET/CT. Of the 25 patients with histologically verified lymph node metastases, uPAR-PET/CT correctly identified regional metastatic disease in 14 patients, with a median lymph node metastasis size of 14 mm (range 3-27 mm). A significant correlation was found between SUVmax and the product of the H-score and tumor depth (r = 0.67; p = 0.003). The sensitivity and specificity of uPAR-PET/CT in detecting regional metastatic disease were 56% and 100%, respectively. When added to CT/MRI, uPAR-PET was able to upstage 2/11 (18%) of patients with occult metastases and increase the sensitivity to 64%. The sensitivity and specificity of 68Ga-NOTA-AE105 uPAR-PET/CT were equivalent to those of CT/MRI. The significant correlation between SUVmax and uPAR expression verified the target specificity of 68Ga-NOTA-AE105. Despite the target specificity, the sensitivity of imaging is too low for nodal staging and it cannot replace neck dissection.

ICAM-1-suPAR-CD11b Axis Is a Novel Therapeutic Target for Metastatic Triple-Negative Breast Cancer

Accumulating evidence demonstrates that circulating tumor cell (CTC) clusters have higher metastatic ability than single CTCs and negatively correlate with cancer patient outcomes. Along with homotypic CTC clusters, heterotypic CTC clusters (such as neutrophil-CTC clusters), which have been identified in both cancer mouse models and cancer patients, lead to more efficient metastasis formation and worse patient outcomes. However, the mechanism by which neutrophils bind to CTCs remains elusive. In this study, we found that intercellular adhesion molecule-1 (ICAM-1) on triple-negative breast cancer (TNBC) cells and CD11b on neutrophils mediate tumor cell-neutrophil binding. Consequently, CD11b deficiency inhibited tumor cell-neutrophil binding and TNBC metastasis. Furthermore, CD11b mediated hydrogen peroxide (H2O2) production from neutrophils. Moreover, we found that ICAM-1 in TNBC cells promotes tumor cells to secrete suPAR, which functions as a chemoattractant for neutrophils. Knockdown of uPAR in ICAM-1+ TNBC cells reduced lung-infiltrating neutrophils and lung metastasis. Bioinformatics analysis confirmed that uPAR is highly expressed in TNBCs, which positively correlates with higher neutrophil infiltration and negatively correlates with breast cancer patient survival. Collectively, our findings provide new insight into how neutrophils bind to CTC to facilitate metastasis and discover a novel potential therapeutic strategy by blocking the ICAM-1-suPAR-CD11b axis to inhibit TNBC metastasis.

Albumin-based drug carrier targeting urokinase receptor for cancer therapy

Urokinase plasminogen activator receptor (uPAR) is a key participant in extracellular proteolysis, tissue remodeling and cell motility. uPAR overexpresses in most solid tumors and several hematologic malignancies, but has low levels on normal tissues, thus is advocated as a molecular target for cancer therapy. One of the obstacles for the evaluation of uPAR targeting agents in preclinical study is the species specificity, where targeting agents for human uPAR  usually not bind to murine uPAR. Here, we develop a targeting agent that binds to both murine and human uPAR. This targeting agent is genetically fused to human serum albumin, a commonly used drug carrier, and the final construct is named as uPAR targeting carrier (uPARTC). uPARTC binds specifically to uPAR-overexpressing 293T/huPAR and 293T/muPAR as demonstrated by flow cytometry. A cytotoxic compound, celastrol, is embedded into uPARTC non-covalently. The resulting macromolecular complex show effective proliferation inhibition on both murine and human uPAR overexpressing cells, and exhibit potent antitumor efficacy on hepatoma H22-bearing mice. This work demonstrates that uPARTC is a promising tumor targeting drug carrier, which address the species-specificity challenge of uPAR targeting agents and can be used to load other cytotoxic compounds.

Structural Dynamics-Driven Discovery of Anticancer and Antimetastatic Effects of Diltiazem and Glibenclamide Targeting Urokinase Receptor

Diltiazem and glibenclamide are commonly used hypotensive and antidiabetic drugs. This study reports the discovery of the potential antitumor and antimetastatic effects of these two drugs using a structural dynamics-driven virtual screening targeting urokinase receptor (uPAR). Owing to uPAR's high flexibility, currently resolved crystal structures of uPAR, all in ligand-bound states, provide limited representations of its physiological conformation. To improve the accuracy of screening, we performed a long-timescale molecular dynamics simulation and obtained the representative conformations of apo-uPAR as the targets for our screening. Experimentally, we demonstrated that diltiazem and glibenclamide bound uPAR with K_D values in the micromolar range. In addition, both compounds effectively suppressed tumor growth and metastasis in a uPAR-dependent manner in vitro and in vivo. This work not only provides two potent uPAR inhibitors but also reports a proof-of-concept study on the potential off-label antitumor and antimetastatic uses of diltiazem and glibenclamide.

Potential of uPAR, αvβ6 Integrin, and Tissue Factor as Targets for Molecular Imaging of Oral Squamous Cell Carcinoma: Evaluation of Nine Targets in Primary Tumors and Metastases by Immunohistochemistry

No clinically approved tumor-specific imaging agents for head and neck cancer are currently available. The identification of biomarkers with a high and homogenous expression in tumor tissue and minimal expression in normal tissue is essential for the development of new molecular imaging targets in head and neck cancer. We investigated the expression of nine imaging targets in both primary tumor and matched metastatic tissue of 41 patients with oral squamous cell carcinoma (OSCC) to assess their potential as targets for molecular imaging. The intensity, proportion, and homogeneity in the tumor and the reaction in neighboring non-cancerous tissue was scored. The intensity and proportion were multiplied to obtain a total immunohistochemical (IHC) score ranging from 0-12. The mean intensity in the tumor tissue and normal epithelium were compared. The expression rate was high for the urokinase-type plasminogen activator receptor (uPAR) (97%), integrin αvβ6 (97%), and tissue factor (86%) with a median total immunostaining score (interquartile range) for primary tumors of 6 (6-9), 12 (12-12), and 6 (2.5-7.5), respectively. For the uPAR and tissue factor, the mean staining intensity score was significantly higher in tumors compared to normal epithelium. The uPAR, integrin αvβ6, and tissue factor are promising imaging targets for OSCC primary tumors, lymph node metastases, and recurrences.

High-throughput optofluidic screening of single B cells identifies novel cross-reactive antibodies as inhibitors of uPAR with antibody-dependent effector functions

The urokinase-type plasminogen activator receptor (uPAR) is an essential regulator for cell signaling in tumor cell proliferation, adhesion, and metastasis. The ubiquitous nature of uPAR in many aggressive cancer types makes uPAR an attractive target for immunotherapy. Here, we present a rapid and successful workflow for developing cross-reactive anti-uPAR recombinant antibodies (rAbs) using high-throughput optofluidic screening of single B-cells from human uPAR-immunized mice. A total of 80 human and cynomolgus uPAR cross-reactive plasma cells were identified, and selected mouse VH/VL domains were linked to the trastuzumab (Herceptin®) constant domains for the expression of mouse-human chimeric antibodies. The resulting rAbs were characterized by their tumor-cell recognition, binding activity, and cell adhesion inhibition on triple-negative breast cancer cells. In addition, the rAbs were shown to enact antibody-dependent cellular cytotoxicity (ADCC) in the presence of either human natural killer cells or peripheral blood mononuclear cells, and were evaluated for the potential use of uPAR-targeting antibody-drug conjugates (ADCs). Three lead antibodies (11857, 8163, and 3159) were evaluated for their therapeutic efficacy in vivo and were shown to suppress tumor growth. Finally, the binding epitopes of the lead antibodies were characterized, providing information on their unique binding modes to uPAR. Altogether, the strategy identified unique cross-reactive antibodies with ADCC, ADC, and functional inhibitory effects by targeting cell-surface uPAR, that can be tested in safety studies and serve as potential immunotherapeutics.

The Role of Selected Serpins in Gastrointestinal (GI) Malignancies

Gastrointestinal (GI) cancers, which are a diverse group of malignant diseases, represent a major healthcare problem around the world. Due to the lack of specific symptoms in the early stages as well as insufficient diagnostic possibilities, these malignancies occupy the leading position in the causes of death worldwide. The currently available tests have too many limitations to be part of routine diagnostics. Therefore, new potential biomarkers that could be used as diagnostic and prognostic factors for these cancers are still being sought. Among the proteins that might fit this role are serpins, which are serine protease inhibitors. Although the serpins themselves have been known for many years, they have recently become the centre of attention for many authors, especially due to the fact that a number of proteins in this family are involved in many stages of neoplasia formation, from angiogenesis through tumour growth to progression. Therefore, the aim of this review is to present the current knowledge about the significance of serpins in GI malignancies, especially their involvement in the development and progression of oesophageal, gastric, pancreatic and colorectal cancers. This review summarises and confirms the important roles of selected serpins in the pathogenesis of various GI cancers and also points to their promising roles as therapeutic targets. However, due to the relatively nonspecific nature of serpins, future research should be carried out to elucidate the mechanisms involved in tumour pathogenesis in more detail.

Personalized Targeted Therapeutic Strategies against Oral Squamous Cell Carcinoma. An Evidence-Based Review of Literature

Oral squamous cell carcinoma (OSCC) is the most common type of malignant tumor in the head and neck, with a poor prognosis mainly due to recurrence and metastasis. Classical treatment modalities for OSCC like surgery and radiotherapy have difficulties in dealing with metastatic tumors, and together with chemotherapy, they have major problems related to non-specific cell death. Molecular targeted therapies offer solutions to these problems through not only potentially maximizing the anticancer efficacy but also minimizing the treatment-related toxicity. Among them, the receptor-mediated targeted delivery of anticancer therapeutics remains the most promising one. As OSCC exhibits a heterogeneous nature, selecting the appropriate receptors for targeting is the prerequisite. Hence, we reviewed the OSCC-associated receptors previously used in targeted therapy, focused on their biochemical characteristics and expression patterns, and discussed the application potential in personalized targeted therapy of OSCC. We hope that a better comprehension of this subject will help to provide the fundamental information for OSCC personalized therapeutic planning.

Expression patterns of uPAR, TF and EGFR and their potential as targets for molecular imaging in oropharyngeal squamous cell carcinoma

The clinical introduction of molecular imaging for the management of oropharyngeal squamous cell carcinoma (OPSCC) relies on the identification of relevant cancer-specific biomarkers. The application of three membrane-bound receptors, namely urokinase-type plasminogen activator receptor (uPAR), tissue factor (TF) and EGFR have been previously explored for targeted imaging and therapeutic strategies in a broad range of solid cancers. The present study aimed to investigate the expression patterns of uPAR, EGFR and TF by immunohistochemistry (IHC) to evaluate their potential for targeted imaging and prognostic value in OPSCC. In a retrospective cohort of 93 patients with primary OPSCC, who were balanced into the 45 human papillomavirus (HPV)-positive and 48 HPV-negative groups, the IHC-determined expression profiles of uPAR, TF and EGFR in large biopsy or tumor resection specimens were analyzed. Using the follow-up data, overall survival (OS) and recurrence-free survival were measured. Specifically, associations between survival outcome, biomarker expression and clinicopathological factors were examined using Cox proportional hazards model and log-rank test following Kaplan-Meier statistics. After comparing the expression pattern of biomarkers within the tumor compartment with that in the adjacent normal tissues, uPAR and TF exhibited a highly tumor-specific expression pattern, whereas EGFR showed a homogeneous expression within the tumor compartment as well as a consistent expression in the normal mucosal epithelium and salivary gland tissues. The positive expression rate of uPAR, TF and EGFR in the tumors was 98.9, 76.3 and 98.9%, respectively. No statistically significant association between biomarker expression and survival outcome could be detected. Higher uPAR expression levels had a trend towards reduced OS according to results from univariate analysis (P=0.07; hazard ratio=2.01; 95% CI=0.92-4.37). Taken together, these results suggest that uPAR, TF and EGFR may be suitable targets for molecular imaging and therapy in OPSCC. In particular, uPAR may be an attractive target owing to their high positive expression rates in tumors and a highly tumor-specific expression pattern.

Urokinase Receptor uPAR Downregulation in Neuroblastoma Leads to Dormancy, Chemoresistance and Metastasis

Simple Summary

uPAR is a membrane receptor that contributes to extracellular matrix remodeling and controls cellular adhesion, proliferation, survival, and migration. We demonstrate that the initially high uPAR expression predicts poor survival in neuroblastoma. However, relapsed neuroblastomas have a significantly decreased uPAR expression. uPAR downregulation in neuroblastoma cells leads to dormancy and resistance to chemotherapeutic drugs. In mice, low uPAR-expressing neuroblastoma cells formed smaller primary tumors but more frequent metastasis.

Abstract

uPAR is a membrane receptor that binds extracellular protease urokinase, contributes to matrix remodeling and plays a crucial role in cellular adhesion, proliferation, survival, and migration. uPAR overexpression in tumor cells promotes mitogenesis, opening a prospective avenue for targeted therapy. However, uPAR targeting in cancer has potential risks. We have recently shown that uPAR downregulation in neuroblastoma promotes epithelial-mesenchymal transition (EMT), potentially associated with metastasis and chemoresistance. We used data mining to evaluate the role of uPAR expression in primary and relapsed human neuroblastomas. To model the decreased uPAR expression, we targeted uPAR using CRISPR/Cas9 and shRNA in neuroblastoma Neuro2a cells and evaluated their chemosensitivity in vitro as well as tumor growth and metastasis in vivo. We demonstrate that the initially high PLAUR expression predicts poor survival in human neuroblastoma. However, relapsed neuroblastomas have a significantly decreased PLAUR expression. uPAR targeting in neuroblastoma Neuro2a cells leads to p38 activation and an increased p21 expression (suggesting a dormant phenotype). The dormancy in neuroblastoma cells can be triggered by the disruption of uPAR-integrin interaction. uPAR-deficient cells are less sensitive to cisplatin and doxorubicin treatment and exhibit lower p53 activation. Finally, low uPAR-expressing Neuro2a cells formed smaller primary tumors, but more frequent metastasis in mice. To the best of our knowledge, this is the first study revealing the pathological role of dormant uPAR-deficient cancer cells having a chemoresistant and motile phenotype.

Polymeric biocompatible iron oxide nanoparticles labeled with peptides for imaging in ovarian cancer

Compared with other nanomaterials, surface-modified iron oxide nanoparticles (IONPs) have gained attraction for cancer therapy applications due to its low toxicity, and long retention time. An innocuous targeting strategy was developed by generation of fluorescein isothiocyanate (FITC)-labeled peptide (growth factor domain (GFD) and somatomedin B domain (SMB)) functionalized, chitosan-coated IONPs (IONPs/C). It can be used to target urokinase plasminogen activator receptor (uPAR), which is a surface biomarker, in ovarian cancer. Binding affinity between uPAR and peptides (GFD and SMB) were revealed by in-silico docking studies. The biophysical characterizations of IONPs, IONPs/C, and IONPs/C/GFD-FITC or SMB-FITC nanoprobes were assessed via Vibrating Sample Magnetometer (VSM), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), and Fourier Transform Infrared Spectroscopy (FT-IR). Prussian Blue staining, fluorescence spectroscopy, and fluorescence imaging were performed to confirm the targeting of nanoprobes with the surface receptor uPAR. The combination of IONPs/C/GFD+SMB showed efficient targeting of uPAR in the tumor microenvironment, and thus can be implemented as a molecular magnetic nanoprobe for cancer cell imaging and targeting.

DNAzymes, Novel Therapeutic Agents in Cancer Therapy: A Review of Concepts to Applications

The past few decades have witnessed a rapid evolution in cancer drug research which is aimed at developing active biological interventions to regulate cancer-specific molecular targets. Nucleic acid-based therapeutics, including ribozymes, antisense oligonucleotides, small interference RNA (siRNA), aptamer, and DNAzymes, have emerged as promising candidates regulating cancer-specific genes at either the transcriptional or posttranscriptional level. Gene-specific catalytic DNA molecules, or DNAzymes, have shown promise as a therapeutic intervention against cancer in various in vitro and in vivo models, expediting towards clinical applications. DNAzymes are single-stranded catalytic DNA that has not been observed in nature, and they are synthesized through in vitro selection processes from a large pool of random DNA libraries. The intrinsic properties of DNAzymes like small molecular weight, higher stability, excellent programmability, diversity, and low cost have brought them to the forefront of the nucleic acid-based therapeutic arsenal available for cancers. In recent years, considerable efforts have been undertaken to assess a variety of DNAzymes against different cancers. However, their therapeutic application is constrained by the low delivery efficiency, cellular uptake, and target detection within the tumour microenvironment. Thus, there is a pursuit to identify efficient delivery methods in vivo before the full potential of DNAzymes in cancer therapy is realized. In this light, a review of the recent advances in the use of DNAzymes against cancers in preclinical and clinical settings is valuable to understand its potential as effective cancer therapy. We have thus sought to firstly provide a brief overview of construction and recent improvements in the design of DNAzymes. Secondly, this review stipulates the efficacy, safety, and tolerability of DNAzymes developed against major hallmarks of cancers tested in preclinical and clinical settings. Lastly, the recent advances in DNAzyme delivery systems along with the challenges and prospects for the clinical application of DNAzymes as cancer therapy are also discussed.

uPAR: An Essential Factor for Tumor Development

Tumorigenesis is closely related to the loss of control of many genes. Urokinase-type plasminogen activator receptor (uPAR), a glycolipid-anchored protein on the cell surface, is controlled by many factors in tumorigenesis and is expressed in many tumor tissues. In this review, we summarize the regulatory effects of the uPAR signaling pathway on processes and factors related to tumor progression, such as tumor cell proliferation, adhesion, metastasis, glycolysis, tumor microenvironment and angiogenesis. Overall, the evidence accumulated to date suggests that uPAR induction by tumor progression may be one of the most important factors affecting therapeutic efficacy. An improved understanding of the interactions between uPAR and its coreceptors in cancer will provide critical biomolecular information that may help to better predict the disease course and response to therapy.

The Urokinase Receptor (uPAR) as a "Trojan Horse" in Targeted Cancer Therapy: Challenges and Opportunities

Simple Summary

Discovered more than three decades ago, the urokinase-type plasminogen activator receptor (uPAR) has now firmly established itself as a versatile molecular target holding promise for the treatment of aggressive malignancies. The copious abundance of uPAR in virtually all human cancerous tissues versus their healthy counterparts has fostered a gradual shift in the therapeutic landscape targeting this receptor from function inhibition to cytotoxic approaches to selectively eradicate the uPAR-expressing cells by delivering a targeted cytotoxic insult. Multiple avenues are being explored in a preclinical setting, including the more innovative immune- or stroma targeting therapies. This review discusses the current state of these strategies, their potentialities, and challenges, along with future directions in the field of uPAR targeting.

Abstract

One of the largest challenges to the implementation of precision oncology is identifying and validating selective tumor-driving targets to enhance the therapeutic efficacy while limiting off-target toxicity. In this context, the urokinase-type plasminogen activator receptor (uPAR) has progressively emerged as a promising therapeutic target in the management of aggressive malignancies. By focalizing the plasminogen activation cascade and subsequent extracellular proteolysis on the cell surface of migrating cells, uPAR endows malignant cells with a high proteolytic and migratory potential to dissolve the restraining extracellular matrix (ECM) barriers and metastasize to distant sites. uPAR is also assumed to choreograph multiple other neoplastic stages via a complex molecular interplay with distinct cancer-associated signaling pathways. Accordingly, high uPAR expression is observed in virtually all human cancers and is frequently associated with poor patient prognosis and survival. The promising therapeutic potential unveiled by the pleiotropic nature of this receptor has prompted the development of distinct targeted intervention strategies. The present review will focus on recently emerged cytotoxic approaches emphasizing the novel technologies and related limits hindering their application in the clinical setting. Finally, future research directions and emerging opportunities in the field of uPAR targeting are also discussed.

Quercetin Inhibits the Epithelial to Mesenchymal Transition through Suppressing Akt Mediated Nuclear Translocation of β-Catenin in Lung Cancer Cell Line

Lung cancer is a first leading cause of cancer related death worldwide. Quercetin (QUE) has chemo-preventive effect against a variety of cancers. However, the molecular mechanism of QUE mediated inhibition of cancer cell migration and epithelial to mesenchymal transition (EMT) is not clear in lung cancer. Therefore, this study investigates the effect of QUE on EMT and metastasis of lung cancer cell line (A549). The MTT assay, scratch wound healing assay, Transwell migration and invasion assay performed to assess the cell viability and migration potential of lung cancer cells after treatment with different concentration of QUE. Further, chemokines gene expression was analyzed by qPCR and EMT markers were analyzed by immunocytochemistry and Western blot. QUE inhibits cell viability in a dose-dependent (10-80 μM) manner both at 24 and 48 h treatment. The Akt/MAPK/β-catenin and EMT marker protein expressions were decreased significantly, whereas TIMP-2 expression was increased upon QUE treatment. QUE inhibits cell migration and invasion of A-549 cells. In addition, Immunocytochemistry result showed that QUE can reduce nuclear translocalisation of β-catenin in A549 cells. Our results suggest that QUE can inhibit the metastatic potential in lung cancer by altering the Akt/MAPK/β-catenin signaling pathway and inhibiting the nuclear translocation of β-catenin.

Extrahepatic metastases from hepatocellular carcinoma: multimodality image evaluation

The most prevalent primary malignancy of the liver is hepatocellular carcinoma (HCC); its poor prognosis is mainly related to intrahepatic recurrence and extrahepatic metastases. However, survival from HCC has improved due to better control of the primary tumor, the development of newer treatment modalities, including liver transplant, together with advances in imaging techniques. Therefore, the significance of patient management as corresponds with distant metastases has increased; since the proper evaluation and detection of extrahepatic metastases is crucial to optimize potential therapy for patients. Conventional imaging like CT, MRI play crucial rule in patient's diagnosis and qualifying for a certain type of therapy. More recently, a molecular imaging tool with radiolabeled deoxyglucose and fluorocholine has proved its promising value as a complementary tool to conventional studies. In this review, the frequent sites of metastases and HCC spread are discussed as well as the imaging findings as seen by both conventional imaging techniques and by molecular imaging tools, namely 18F-Choline PET/CT, and FDG PET. The implications of guiding treatment planning have also been discussed.

The Urokinase Receptor: A Multifunctional Receptor in Cancer Cell Biology. Therapeutic Implications

Proteolysis is a key event in several biological processes; proteolysis must be tightly controlled because its improper activation leads to dramatic consequences. Deregulation of proteolytic activity characterizes many pathological conditions, including cancer. The plasminogen activation (PA) system plays a key role in cancer; it includes the serine-protease urokinase-type plasminogen activator (uPA). uPA binds to a specific cellular receptor (uPAR), which concentrates proteolytic activity at the cell surface, thus supporting cell migration. However, a large body of evidence clearly showed uPAR involvement in the biology of cancer cell independently of the proteolytic activity of its ligand. In this review we will first describe this multifunctional molecule and then we will discuss how uPAR can sustain most of cancer hallmarks, which represent the biological capabilities acquired during the multistep cancer development. Finally, we will illustrate the main data available in the literature on uPAR as a cancer biomarker and a molecular target in anti-cancer therapy.

A review of tumor-specific fluorescence-guided surgery for colorectal cancer

The present study reviews the use of tumor-specific antibodies conjugated to fluorescent dyes in preclinical and clinical studies to enhance visualization of primary tumors and metastases for fluorescence-guided surgery (FGS) in colorectal cancer (CRC). A search strategy was developed using the peer-reviewed National Center for Biotechnology Information (NCBI) database on PubMed. Studies using tumor-specific fluorescence imaging and FGS techniques on murine models of colorectal cell lines or patient-derived orthotopic xenograft (PDOX) colorectal cancer are reviewed. A total of 24 articles were identified that met the inclusion criteria, 21 preclinical and 3 clinical trials. The most widely used target antigen in preclinical and clinical trials was carcinoembryonic antigen (CEA). Mouse studies and clinical studies have demonstrated that the use of FGS in CRC can aid in decreased residual tumor and decreased rates of recurrence. As the mainstay of colorectal cancer treatment is surgery, the addition of intraoperative fluorescence imaging can help locate tumor margins, visualize occult micro-metastases, drive surgical decision making and improve patient outcomes.

Development of inhibitors for uPAR: blocking the interaction of uPAR with its partners

Urokinase-type plasminogen activator receptor (uPAR) mediates a multitude of biological activities, has key roles in several clinical indications, including malignancies and inflammation, and, thus, has attracted intensive research over the past few decades. The pleiotropic functions of uPAR can be attributed to its interaction with an array of partners. Many inhibitors have been developed to intervene with the interaction of uPAR with these partners. Here, we review the development of these classes of uPAR inhibitor and their inhibitory mechanisms to promote the translation of these inhibitors to clinical applications.

New Pieces in the Puzzle of uPAR Role in Cell Migration Mechanisms

The urokinase (uPA) receptor (uPAR) plays a key role in cell migration. We previously showed that uPAR-negative HEK-293 cells efficiently migrate toward serum but, after uPAR ectopic expression, migrate only in a uPAR-dependent manner. In fact, migration of uPAR-transfected HEK-293 (uPAR-293) cells is impaired by anti-uPAR antibodies, without recovery of the uPAR-independent migration mechanisms formerly active. Prostate carcinoma PC3 cells, which express high endogenous uPAR levels, migrated only through a uPAR-dependent mechanism; in fact, the silencing of uPAR expression inhibited their migration. We hypothesize a crucial role of the uPAR glycosyl-phosphatidyl-inositol (GPI) tail, which promotes uPAR partitioning to lipid rafts, in uPAR-controlled cell migration. Here, we show that removal of the uPAR GPI-tail, or lipid rafts disruption by methyl-beta-cyclodextrin impairs migration of PC3 cells, incapable of uPAR-independent migration, whereas it restores uPAR-independent migration in uPAR-293 cells. We then show that, in PC3 cells, both uPAR signaling partners, β1 integrins and receptors for formylated peptides (FPRs), partly associate with lipid rafts. Inhibition of their interaction with uPAR impairs this association and impairs cell migration. Interestingly, blocking uPAR association with FPRs also impairs β1 integrin partitioning to lipid rafts, whereas blocking its association with β1 integrins has no effect on FPRs partitioning. On these bases, we propose that uPAR controls cell migration by connecting β1 integrins and FPRs and, through its GPI tail, by driving them into lipid rafts, thus promoting pro-migratory signals. uPAR-mediated partitioning of integrins to lipid rafts is strictly dependent on uPAR association with FPRs.

The Association between Plasma Levels of Intact and Cleaved uPAR Levels and the Risk of Biochemical Recurrence after Radical Prostatectomy for Prostate Cancer

Radical prostatectomy (RP) is a curatively intended treatment option for clinically localized non-metastatic prostate cancer (PCa). Novel biomarkers could refine treatment choice based on a better identification of men at risk of biochemical recurrence (BCR) following therapy. The urokinase plasminogen activator receptor (uPAR) system is a promising biomarker of aggressiveness in many cancers. The predictive value of uPAR after curatively intended treatment for PCa remains to be elucidated. This was a prospective evaluation of uPAR analysis in men with prostate cancer (Copenhagen uPAR prostate cancer (CuPCA) database). Risk of BCR following RP was analyzed using cumulative incidences with competing risk and tested with Gray’s test. Associations between quartile groups of uPAR levels and BCR were assessed with uni- and multivariate Cox proportional hazards. In total, 532 men were included. With more advanced tumor stage, Gleason score (GS), and prostate-specific antigen (PSA) the uPAR I–III + II–III plasma levels increased. Quartile levels of plasma uPAR I–III, I–III + II–III showed no significant association between the risk of BCR and the plasma uPAR levels in uni- and multivariate analysis. Despite increased levels of uPAR I–III + II–III in advanced tumor stage, intact and cleaved uPAR levels were not associated with BCR and are not predictive biomarkers for BCR following curatively intended treatment of PCa. It is unlikely that further studies of uPAR in RP treated patients is needed.

Fluorescence guided intraluminal endoscopy in the gastrointestinal tract: A systematic review

BACKGROUND

Conventional endoscopy is based on full spectrum white light. However, different studies have investigated the use of fluorescence based endoscopy systems where the white light has been supplemented by infrared light and the use of relevant fluorophores. Fluorescence endoscopy utilizes the fluorescence emitted from a fluorophore, visualizing what is not visible to the naked eye.

AIM

To explore the feasibility of fluorescence endoscopy and evaluate its use in diagnosing and evaluating gastrointestinal disease.

METHODS

We followed the PRISMA guidelines for this systematic review. The research covered five databases; PubMed, Scopus, Web of Science, Embase, and the Cochrane Collection, including only studies in English and Scandinavian languages. Authors screened title and abstract for inclusion, subsequently full-text for inclusion according to eligibility criteria listed in the protocol. The risk of bias was assessed for all studies according to the Newcastle-Ottawa Scale. The authors extracted the data and reported the results in both text and tables.

RESULTS

We included seven studies in the systematic review after screening a total of 2769 papers. The most prominent fluorophore was indocyanine green (n = 6), and whereas one study (n = 1) used Bevacizumab 800-CW. Three studies investigated fluorescence endoscopy in detecting varices, adenomas in patients with familial adenomatous polyposis and neoplasms in the gastrointestinal tract. Four studies evaluated the usefulness of fluorescence endoscopy in assessing tumor invasion. Three of the four studies reported an exceptional diagnostic accuracy (93%, 89% and 88%) in assessing tumor invasion, thus representing better visualization and more correct diagnosis by fluorescence endoscopy compared with the conventional endoscopy. The relationship between the endoscopic findings, tumor invasion, and tumor vascularity was evaluated in two studies showing a significant correlation (^dP < 0.05 and ^bP < 0.01).

CONCLUSION

The use of fluorescence endoscopy is a promising method adding diagnostic value in the detection of neoplasia, adenomas, and assessment of tumor invasion within the gastrointestinal tract. More studies are needed to utilize the feasibility of fluorescence endoscopy compared with other endoscopic methods.

Differential Impact of Calcitriol and Its Analogs on Tumor Stroma in Young and Aged Ovariectomized Mice Bearing 4T1 Mammary Gland Cancer

(1) Background: Vitamin D compounds (VDC) are extensively studied in the field of anticancer properties, including breast cancer. Previously, we showed that calcitriol and its analogs (PRI-2191 and PRI-2205) stimulate metastasis in 4T1 murine mammary gland cancer models in young mice, whereas the reverse effect was observed in aged ovariectomized (OVX) mice; (2) Methods: We determined the phenotype of monocytes/macrophages using FACS and examined the expression of selected genes and proteins by Real-Time PCR and ELISA; (3) Results: Activities of VDC are accompanied by an increase in the percentage of Ly6Clow anti-inflammatory monocytes in the spleen of young and a decrease in aged OVX mice. Treatment of young mice with VDC resulted in an increase of CCL2 plasma and tumor concentration and Arg1 in tumor. In later stage of tumor progression the expression of genes related to metastasis in lung tissue was decreased or increased, in old OVX or young mice, respectively; (4) Conclusions: Pro- or anti-metastatic effects of calcitriol and its analogs in young or aged OVX mice, respectively, can be attributed to the differences in the effects of VDC on the tumor microenvironment, as a consequence of differences in the immunity status of young and aged mice.

Unconventional Secondary Structure Mimics: Ladder-Rungs

Secondary structures tend to be recognizable because they have repeating structural motifs, but mimicry of these does not have to follow such well-defined patterns. Bioinformatics studies to match side-chain orientations of a novel hydantoin triazole chemotype (1) to protein-protein interfaces revealed it tends to align well across parallel and antiparallel sheets, like rungs on a ladder. One set of these overlays was observed for the protein-protein interaction uPA⋅uPAR. Consequently, chemotype 1 was made with appropriate side-chains to mimic uPA at this interface. Biophysical assays indicate these compounds did in fact bind uPAR, and elicit cellular responses that affected invasion, migration, and wound healing.

CD49b, CD87, and CD95 Are Markers for Activated Cancer-Associated Fibroblasts Whereas CD39 Marks Quiescent Normal Fibroblasts in Murine Tumor Models

Fibroblasts are thought to be key players in the tumor microenvironment. Means to identify and isolate fibroblasts as well as an understanding of their cancer-specific features are essential to dissect their role in tumor biology. To date, the identification of cancer-associated fibroblasts is widely based on generic markers for activated fibroblasts in combination with their origin in tumor tissue. This study was focused on a deep characterization of the cell surface marker profile of cancer-associated fibroblasts in widely used mouse tumor models and defining aberrant expression profiles by comparing them to their healthy counterparts. We established a generic workflow to isolate healthy and cancer-associated fibroblasts from solid tissues, thereby reducing bias, and background noise introduced by non-target cells. We identified CD87, CD44, CD49b, CD95, and Ly-6C as cancer-associated fibroblast cell surface markers, while CD39 was identified to mark normal fibroblasts from healthy tissues. In addition, we found a functional association of most cancer-related fibroblast markers to proliferation and a systemic upregulation of CD87, and CD49b in tumor-bearing mice, even in non-affected tissues. These novel markers will facilitate the characterization of fibroblasts and shed further light in their functions and implication in cancer progression.

Basing on uPAR-binding fragment to design chimeric antigen receptors triggers antitumor efficacy against uPAR expressing ovarian cancer cells

Due to the success of chimeric antigen receptors (CARs) in hematological tumors, CARs are also being studied to treat solid tumors. Improving the ability of CARs to penetrate solid tumor tissues is one of the biggest challenges. As the most malignant cancer of the female reproductive system, the survival rate of ovarian cancer has not been significantly improved by traditional therapy methods; therefore, it is necessary to develop new therapeutic targets and new immunotherapy methods for ovarian cancer. UPAR is a glysocylphosphatidylinositol (GPI) anchoring membrane protein that is differentially expressed in normal tissues and ovarian cancer tissues. It has been shown that uPAR up-regulation promotes tumor development, proliferation, invasion, and metastasis, and uPAR is also up-regulated in tumor matrix components. In our study, CARs were designed using the natural ligand binding fragment of uPAR for ovarian cancer.

Vitronectin as a molecular player of the tumor microenvironment in neuroblastoma

Background

Vitronectin is a multifunctional glycoprotein known in several human tumors for its adhesive role in processes such as cell growth, angiogenesis and metastasis. In this study, we examined vitronectin expression in neuroblastoma to investigate whether this molecule takes part in cell-cell or cell-extracellular matrix interactions that may confer mechanical properties to promote tumor aggressiveness.

Methods

We used immunohistochemistry and image analysis tools to characterize vitronectin expression and to test its prognostic value in 91 neuroblastoma patients. To better understand the effect of vitronectin, we studied its in vitro expression using commercial neuroblastoma cell lines and in vivo using intra-adrenal gland xenograft models by immunohistochemistry.

Results

Digital image analysis allowed us to associate vitronectin staining intensity and location discriminating between territorial vitronectin and interterritorial vitronectin expression patterns. High territorial vitronectin expression (strong staining associated with pericellular and intracellular location) was present in tumors from patients with metastatic undifferentiating neuroblastoma, that were MYCN amplified, 11q deleted or with segmental chromosomal profiles, in the high-risk stratification group and with high genetic instability. In vitro studies confirmed that vitronectin is expressed in tumor cells as small cytoplasmic dot drops. In vivo experiments revealed tumor cells with high and dense cytoplasmic vitronectin expression.

Conclusions

These findings highlight the relevance of vitronectin in neuroblastoma tumor biology and suggest its potential as a future therapeutic target in neuroblastoma.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5693-2) contains supplementary material, which is available to authorized users.

Overview of tissue kallikrein and kallikrein-related peptidases in breast cancer

The kallikrein family comprises tissue kallikrein and 14 kallikrein-related peptidases (KLKs) recognized as a subgroup of secreted trypsin- or chymotrypsin-like serine proteases. KLKs are expressed in many cellular types where they regulate important physiological activities such as semen liquefaction, immune response, neural development, blood pressure, skin desquamation and tooth enamel formation. Tissue kallikrein, the oldest member and kinin-releasing enzyme, and KLK3/PSA, a tumor biomarker for prostate cancer are the most prominent components of the family. Additionally, other KLKs have shown an abnormal expression in neoplasia, particularly in breast cancer. Thus, increased levels of some KLKs may increase extracellular matrix degradation, invasion and metastasis; other KLKs modulate cell growth, survival and angiogenesis. On the contrary, KLKs can also inhibit angiogenesis and produce tumor suppression. However, there is a lack of knowledge on how KLKs are regulated in tumor microenvironment by molecules present at the site, namely cytokines, inflammatory mediators and growth factors. Little is known about the signaling pathways that control expression/secretion of KLKs in breast cancer, and further how activation of PAR receptors may contribute to functional activity in neoplasia. A better understanding of these molecular events will allow us to consider KLKs as relevant therapeutic targets for breast cancer.

PBK overexpression promotes metastasis of hepatocellular carcinoma via activating ETV4-uPAR signaling pathway

Invasion and metastasis are the predominant causes of lethal outcomes in patients with hepatocellular carcinoma (HCC). However, the molecular mechanism underlying the invasive or metastatic process are still insufficiently understood. Here, we first integrated several public databases and identified a novel protein kinase, PDZ-binding kinase (PBK) that was frequently upregulated and correlated with poor prognosis in patients with HCC. Gain- or loss-of-function analysis revealed that PBK promoted migration and invasion of HCC cells both in vitro and in vivo. Mechanistically, PBK enhanced uPAR expression by activating its promoter activity. Chromatin immunoprecipitation (ChIP) assay showed that ETV4 directly bound to the core region of uPAR promoter while PBK could enhance the binding of ETV4 to uPAR promoter. In orthotopic mouse model, PBK knockdown markedly inhibited the lung metastasis of HCC cells, while this effect was significantly restored by uPAR overexpression. Finally, there was a positive correlation between PBK and uPAR, ETV4 and uPAR in HCC clinical samples. Collectively, these findings revealed that PBK acted as a crucial kinase by promoting invasion and migration via the ETV4-uPAR signaling pathway, and it therefore could be a promising diagnostic biomarker and therapeutic target for HCC metastasis.

Targeting uPAR by CRISPR/Cas9 System Attenuates Cancer Malignancy and Multidrug Resistance

Urokinase plasminogen activator receptor (uPAR), a member of the lymphocyte antigen 6 protein superfamily, is overexpressed in different types of cancers and plays an important role in tumorigenesis and development. In this study, we successfully targeted uPAR by CRISPR/Cas9 system in two human cancer cell lines with two individual sgRNAs. Knockout of uPAR inhibited cell proliferation, migration and invasion. Furthermore, knockout of uPAR decreases resistance to 5-FU, cisplatin, docetaxel, and doxorubicin in these cells. Although there are several limitations in the application of CRISPR/Cas9 system for cancer patients, our study offers valuable evidences for the role of uPAR in cancer malignancy and drug resistance.

Evaluation of Plasma Urokinase-Type Plasminogen Activator Receptor (UPAR) in Patients With Chronic Hepatitis B, C and Non-Alcoholic Fatty Liver Disease (NAFLD) as Serological Fibrosis Marker

BACKGROUND/AIMS

Progressive hepatic fibrosis is the main predictor of outcome and prognosis in chronic liver diseases. The importance of the coagulation cascade has been defined in liver fibrosis; however, the role of the fibrinolytic pathway has not been clear yet. We aimed to evaluate the association between the plasma levels of soluble urokinase Plasminogen Activator Receptor (uPAR) and the severity of liver fibrosis in chronic hepatitis B, C and Non-Alcoholic Fatty Liver Disease (NAFLD).

METHODS

96 chronic hepatitis B, 22 chronic hepatitis C and 11 NAFLD patients together with 47 healthy controls were enrolled in the study. uPAR plasma levels were detected by Enzyme-Linked Immunosorbent Assay (ELISA) method.

RESULTS

The plasma levels of uPAR in patients with chronic hepatitis B and C significantly exceeded those of healthy controls (P < 0.001) while mean uPAR levels in patients with NAFLD were not different from healthy controls. Mean uPAR levels in chronic viral hepatitis patients with F1-F3 fibrosis and F4-F6 fibrosis were higher than those of control group (P < 0.001). Mean uPAR level in patients with F4-F6 fibrosis was significantly higher than that of patients with F1-F3 fibrosis (P < 0.001).

CONCLUSION

This is the first study that investigated uPAR as a fibrosis marker in NAFLD and chronic hepatitis B patients. It is suggested that plasma levels of uPAR are closely related to the fibrosis stage in chronic hepatitis B and C and that uPAR might be a noninvasive marker of liver fibrosis.

Silencing of uPAR via RNA interference inhibits invasion and migration of oral tongue squamous cell carcinoma

Overexpression of urokinase-type plasminogen activator receptor (uPAR) has been implicated in promoting tumor invasion in various cancer types, including oral tongue squamous cell carcinoma (OTSCC); therefore, the effect of suppressing uPAR expression on the invasive and metastatic potential of OTSCC was investigated. A total of 65 paraffin-embedded tissues were obtained from patients with OTSCC. Immunohistochemistry was used to determine the expression level of uPAR. The Ts cells transfected with short hairpin RNA targeting uPAR were constructed and validated. The cells were used in a number of in vitro analyses, including migration, invasion and western blot analysis assays. Furthermore, a mouse lung metastatic model was used to detect the metastatic ability of OTSCC cells in the lungs. OTSCC cell metastasis and relapse were determined to be associated with uPAR immunopositivity. Inhibition of uPAR expression in Ts cells demonstrated a 40% decrease in migration and a 60% decrease in invasion in vitro, with an associated downregulation of matrix metalloprotease (MMP)-2, MMP-9 and phosphorylated extracellular signal-regulated kinase. In vivo analysis indicated a 90% decrease in the number of mice bearing macroscopic lung metastases. In conclusion, the present study demonstrated that the targeting of uPAR-inhibited cellular proliferation and invasion would provide a potential treatment for OTSCC in the future.

A novel oncogenic role for urokinase receptor in leukemia cells: molecular sponge for oncosuppressor microRNAs

Urokinase receptor (uPAR) expression is up-regulated and represents a negative prognostic marker in most cancers. We previously reported that uPAR and CXCR4 can be regulated by common microRNAs in leukemia cells. Transcripts containing response elements for shared microRNAs in their 3’UTR may regulate their availability.

We investigated uPAR 3’UTR capability to recruit microRNAs, thus regulating the expression of their targets. uPAR 3’UTR transfection in KG1 leukemia cells up-regulates the expression of endogenous uPAR. Transfection of uPAR 3’UTR, inserted downstream a reporter gene, increases uPAR expression and simultaneously down-regulates the reporter gene expression. Transfection of uPAR 3’UTR also increases CXCR4 expression; accordingly, uPAR silencing induces down-regulation of CXCR4 expression, through a mechanism involving Dicer, the endoribonuclease required for microRNA maturation.

Transfection of uPAR 3’UTR also increases the expression of pro-tumoral factors and modulates cell adhesion and migration, consistently with the capability of uPAR3’UTR-recruited microRNAs to target several and different transcripts and, thus, functions.

Finally, we found 3’UTR-containing variants of uPAR transcript in U937 leukemia cells, which show higher levels of uPAR expression as compared to KG1 cells, in which these variants are not detected.

These results suggest that uPAR mRNA may recruit oncosuppressor microRNAs, allowing the expression of their targets.

Comparative profiling of analog targets: a case study on resveratrol for mouse melanoma metastasis suppression

Many plant-specialized metabolites have remedial properties and provide an endless chemical resource for drug discovery. However, most of these metabolites have promiscuous binding targets in mammalian cells and elicit a series of responses that collectively change the physiology of the cells. To explore the potential of these multi-functional and multi-targeted drugs, it is critical to understand the direct relationships between their key chemical features, the corresponding binding targets and the relevant biological effects, which is a prerequisite for future drug modification and optimization. Methods: We introduced and demonstrated a general workflow, called Comparative Profiling of Analog Targets (CPAT), to connect specific biological effects with defined chemical structures of drugs. Using resveratrol (RSV) as an example, we have synthesized and characterized a series of partial functional analogs of RSV. An analog (named RSVN) that specifically lost the inhibitory effect of RSV in cell migration was identified. The binding targets of RSVN and RSV was profiled and compared. Results: Comparative profiling of the RSV and RSVN binding targets showed that, unlike RSV, RSVN failed to target specific components involved in DNA methylation (histone deacetylase 1 [HDAC1] and DNA methyltransferase 3 alpha [DNMT3a]), suggesting that RSV suppresses cell migration through epigenetic regulation. Indeed, RSV treatment recruited HDAC1 and DNMT3a to the promoter region of the focal adhesion kinase (FAK), a key factor involved in cell adhesion, enhanced the promoter methylation, and thus attenuated the protein expression. The inhibitory effect of RSV in cell migration was diminished once FAK expression was restored. Thus, the mechanism of RSV in inhibiting cell migration could be largely accounted to epigenetically control of FAK expression. Conclusion: Our results showed that even though RSV exhibits promiscuous binding, its inhibitory effect on cell migration can be mechanistically understood. First, the presence of 4'-hydroxystilbene within the RSV structure is essential for this activity. Second, it inhibits cell migration through epigenetically based downregulation of FAK expression. Taken together, we propose that CPAT might also be adapted to delineate the specific function of other natural products (NPs) that exhibit binding promiscuity.

Synergistic potentiation of the anti-metastatic effect of anti EGFR mAb by its combination with immunotherapies targeting the ganglioside NGcGM3

Several Anti-EGFR mAbs are register for the treatment of human cancer. However, their impact on patients overall survival has been limited by tumor resistance. N-Glycolyl variant of GM3 ganglioside (NGcGM3) is specifically expressed in some human tumors, and it has been associated with a poor prognosis. Several reports have documented that GM3 physically associates to EGFR inhibiting its ligand depend phosphorylation, but it also facilitates an alternative/compensatory signaling cascade mediated by Uroquinase Plasminogen Activator Receptor (uPAR) and integrin α5β1 interaction. However, the difference between NGc and N-Acetylated (NAc) variants of GM3 regarding such interactions is unknown. We hypothesized that enrichment of NGcGM3 expression in tumors relates to advantages of this ganglioside, on ensuring both EGFR and uPAR pathways optimal function. We explored the impact of combining an anti-EGFR (7A7 mAb) with anti-NGcGM3 therapies: NGcGM3/VSSP vaccine or 14F7 mAb. Both combinations synergistically increase overall survival in two models of lung metastasis: 3LL-D122 and 4T1; but combination with NGcGM3/VSSP vaccine is significantly more effective. In 3LL-D122-metastasis, of mice treated with the best combination, both EGFR and uPAR/α5β1 integrin pathways are turn off (I.e expression of uPAR/α5β1; and phosphorylation of EGFR, Stat3, Src and FAK are reduced); and tumor angiogenesis is decreased. Interestingly, combination treatment increases tumor infiltrating CD4⁺T, CD8⁺T and NK⁺-cells. Furthermore, a positive clinical outcome is reported for a cancer patient treated with an anti-EGFR mAb and anti-NGcGM3 therapy. Overall, our results support the combination of anti EGFR antibodies with therapies targeting NGcGM3 to increase their efficacy in future clinical trials.

Tristetraprolin: A novel target of diallyl disulfide that inhibits the progression of breast cancer

Diallyl disulfide (DADS), a volatile component of garlic oil, has various biological properties, including antioxidant, antiangiogenic and anticancer effects. The present study aimed to explore novel targets of DADS that may slow or stop the progression of breast cancer. First, xenograft tumor models were created by subcutaneously injecting MCF-7 and MDA-MB-231 breast cancer cells into nude mice. Subsequently, western blot analysis was performed to investigate the expression of tristetraprolin (TTP), urokinase-type plasminogen activator (uPA) and matrix metalloproteinase-9 (MMP-9) in the xenograft tumors, and cell cultures. Tablet cloning, Transwell and wound healing assays revealed that DADS treatment significantly inhibited the proliferation, invasion and migration of breast cancer cells. In addition, DADS treatment led to significant downregulation of uPA and MMP-9 protein expression, but significantly upregulated TTP expression in vivo and in vitro. Knocking down TTP expression using small interfering RNA reversed the aforementioned effects of DADS, which suggests TTP is a key target of DADS in inhibiting the progression of breast cancer.

Integrin-uPAR signaling leads to FRA-1 phosphorylation and enhanced breast cancer invasion

Background

The Fos-related antigen 1 (FRA-1) transcription factor promotes tumor cell growth, invasion and metastasis. Phosphorylation of FRA-1 increases protein stability and function. We identify a novel signaling axis that leads to increased phosphorylation of FRA-1, increased extracellular matrix (ECM)-induced breast cancer cell invasion and is prognostic of poor outcome in patients with breast cancer.

Methods

While characterizing five breast cancer cell lines derived from primary human breast tumors, we identified BRC-31 as a novel basal-like cell model that expresses elevated FRA-1 levels. We interrogated the functional contribution of FRA-1 and an upstream signaling axis in breast cancer cell invasion. We extended this analysis to determine the prognostic significance of this signaling axis in samples derived from patients with breast cancer.

Results

BRC-31 cells display elevated focal adhesion kinase (FAK), SRC and extracellular signal-regulated (ERK2) phosphorylation relative to luminal breast cancer models. Inhibition of this signaling axis, with pharmacological inhibitors, reduces the phosphorylation and stabilization of FRA-1. Elevated integrin α_Vβ₃ and uPAR expression in these cells suggested that integrin receptors might activate this FAK-SRC-ERK2 signaling. Transient knockdown of urokinase/plasminogen activator urokinase receptor (uPAR) in basal-like breast cancer cells grown on vitronectin reduces FRA-1 phosphorylation and stabilization; and uPAR and FRA-1 are required for vitronectin-induced cell invasion. In clinical samples, a molecular component signature consisting of vitronectin-uPAR-uPA-FRA-1 predicts poor overall survival in patients with breast cancer and correlates with an FRA-1 transcriptional signature.

Conclusions

We have identified a novel signaling axis that leads to phosphorylation and enhanced activity of FRA-1, a transcription factor that is emerging as an important modulator of breast cancer progression and metastasis.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0936-8) contains supplementary material, which is available to authorized users.

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.

CMG2 Expression Is an Independent Prognostic Factor for Soft Tissue Sarcoma Patients

The capillary morphogenesis gene 2 (CMG2), also known as the anthrax toxin receptor 2 (ANTXR2), is a transmembrane protein putatively involved in extracellular matrix (ECM) adhesion and tissue remodeling. CMG2 promotes endothelial cell proliferation and exhibits angiogenic properties. Its downregulation is associated with a worsened survival of breast carcinoma patients. Aim of this study was to analyze the CMG2 mRNA and protein expression in soft tissue sarcoma and their association with patient outcome. CMG2 mRNA was measured in 121 tumor samples of soft tissue sarcoma patients using quantitative real-time PCR. CMG2 protein was evaluated in 52 tumor samples by ELISA. CMG2 mRNA was significantly correlated with the corresponding CMG2 protein expression (r_s = 0.31; p = 0.027). CMG2 mRNA expression was associated with the mRNA expressions of several ECM and tissue remodeling enzymes, among them CD26 and components of the uPA system. Low CMG2 mRNA expression was correlated with a worsened patients’ disease-specific survival in Kaplan-Meier analyses (mean patient survival was 25 vs. 96 months; p = 0.013), especially in high-stage tumors. A decreased CMG2 expression is a negative prognostic factor for soft tissue sarcoma patients. CMG2 may be an interesting candidate gene for the further exploration of soft tissue sarcoma genesis and progression.

Expression of a urokinase-type plasminogen activator during tumor growth leads to angiogenesis via galanin activation in tumor-bearing mice

Small-cell lung carcinoma releases progalanin. The released progalanin is activated via a nonclassical processing pathway, being processed into an active form of galanin (1-20) by plasmin in extracellular components. Plasmin is produced from plasminogen activators. To clarify the regulation of progalanin via plasminogen activation by urokinase and tissue-plasminogen activator (t-PA), we investigated the regulation mechanism for urokinase and t-PA expression and their effect on galanin activation. Additionally, we studied the effect of activated galanin on angiogenesis. To determine the effect of cell density, we measured the expression levels of urokinase and t-PA using real-time PCR and plasminogen/gelatin zymography in a cell culture. The urokinase expression increased under both high cell density and presence of cell membrane fractions. However, urokinase increments induced by conditioned medium were low. These results indicate that expression of plasminogen activators is regulated by cell membrane factors. We used tumor-bearing mice to clarify the expression of plasminogen activators and galanin activation. Real-time PCR showed that urokinase was substantially higher in the central parts of tumors compared to the periphery, and this was confirmed by plasminogen/gelatin zymography. To evaluate the biological effect of plasminogen activators on tumor growth, we used tranexamic acid as a plasminogen inhibitor. Tranexamic acid decreased galanin (1-20) and the hemoglobin content of tumors and suppressed tumor growth. Additionally, galanin had no effect on the hemoglobin content of tumors derived from cells lacking GALR2. These results demonstrate the regulation of urokinase expression in tumors through progalanin activation in extracellular compartments, and confirm that galanin plays a role in angiogenesis.

Prognostic value of urokinase plasminogen activator system in non-small cell lung cancer: A systematic review and meta-analysis

Current relevant research suggests there are significant differences between the expression of the urokinase plasminogen activator (uPA) system in cancer tissues and in normal tissues. However, the potential effectiveness of the uPA system as a prognostic biomarker of non-small cell lung cancer (NSCLC) remains unclear. In the present study, a systematic review and meta-analysis were performed to evaluate the relevance of the uPA system in the prognosis of patients with NSCLC. Using the PubMed, EMBASE, Web of Science and Cochrane Library databases, data from relevant academic journal articles were extracted and subjected to analysis. Associations between expression profiles pertaining to the uPA system and the overall survival (OS) of patients with NSCLC were analyzed. The study incorporated data from 11 independent journal articles and these reports included a total of 937 patients with NSCLC. The meta-analysis results revealed that increased expression of urokinase plasminogen activator (uPA) and PA inhibitor type 1 (PAI-1) exhibited no significant association with poor OS [hazard ratio (HR)-uPA=1.07 (0.87-1.31), P=0.53; HR-PAI-1=1.02 (0.63-1.65), P=0.94]. Similarly, reduced expression of PAI type 2 (PAI-2) did not significantly correlate with poor OS [HR-PAI-2=1.58 (0.64-3.90); P=0.32]. Notably, however, a significant association was observed between increased expression levels of uPA receptor (uPAR) and poor OS for NSCLC [HR-uPAR=1.50 (1.04-2.15); P=0.03]. Therefore, the expression of uPAR in the uPA system of patients with NSCLC could be used as a novel clinical biomarker to evaluate the prognosis of NSCLC. The utilization of this biomarker may provide a platform for the further development of targeted drugs for the treatment of NSCLC.

Anticancer effects of methanol extract of Myrmecodia platytyrea Becc. leaves against human hepatocellular carcinoma cells via inhibition of ERK and STAT3 signaling pathways

Myrmecodia platytyrea Becc., a member of the Rubiaceae family, is found throughout Southeast Asia and has been traditionally used to treat cancer. However, there is limited pharmacological information on this plant. We investigated the anticancer effects of the methanol extract of Myrmecodia platytyrea Becc. leaves (MMPL) and determined the molecular mechanisms underlying the effects of MMPL on metastasis in human hepatocellular carcinoma (HCC) cells. MMPL dose-dependently inhibited cell migration and invasion in SK‑Hep1 and Huh7 cells. In addition, MMPL strongly suppressed the enzymatic activity of matrix metalloproteinases (MMP‑2 and MMP‑9). Diminished telomerase activity by MMPL resulted in the suppression of both telomerase activity and telomerase-associated gene expression. The levels of urokinase-type plasminogen activator receptor (uPAR) expression as well as the phosphorylation levels of signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) were also attenuated by MMPL. The above results collectively suggest that MMPL has anticancer effects in HCC and that MMPL can serve as an effective therapeutic agent for treating human liver cancer.