Engineered Antibody Fragment against the Urokinase Plasminogen Activator for Fast Delineation of Triple-Negative Breast Cancer by Positron Emission Tomography.

The urokinase plasminogen activator (uPA) and its cofactors are important regulators of tumor initiation and progression (including metastasis), and its overexpression is associated with unfavorable situations in cancer patients. We have previously used positron emission tomography (PET) imaging with a radiolabeled monoclonal antibody against the uPA (named ATN-291) to detect the uPA signaling activity in various cancer types; however, good tumor contrast can only be observed 24 h postinjection. To shorten the antibody circulation time and decrease interactions of ATN-291 with the mononuclear phagocyte system (MPS), our goal in this study is to develop an engineered antibody fragment (F(ab')2) from the parent antibody. By pepsin digestion and chromatography purification, ATN-291 F(ab')2 was obtained and characterized. Subsequently, it was conjugated with NOTA-Bn-NCS or fluorescein isothiocyanate (FITC) for PET imaging and fluorescence-mediated cellular analysis (i.e., flow cytometry or fluorescence microscopy). We confirmed that ATN-291 F(ab')2 still maintained a good targeting efficacy for the uPA in MDA-MB-231 cells (uPA+) and it had a faster blood clearance speed compared with ATN-291, while its interaction with MPS has been significantly decreased. In rodent tumor xenografts, radiolabeled ATN-291 F(ab')2 had a selective and persistent uptake in MDA-MB-231 tumors, with an early tumor-to-blood ratio of 1.3 ± 0.8 (n = 4) at 2 h postinjection from PET imaging. During our observation, radiolabeled ATN-291 F(ab')2 was excreted from both renal and hepatobiliary pathways. Radiolabeled ATN-291 F(ab')2 was also used for detecting uPA fluctuation during the tumor treatment in test animals. We concluded that radiolabeled ATN-291 F(ab')2 could be used as fast as PET cancer diagnostics with versatile applicability.

Arsenoplatin-1 Is a Dual Pharmacophore Anticancer Agent.

Arsenoplatins are adducts of two chemically important anticancer drugs, cisplatin and arsenic trioxide, that have a Pt(II) bond to an As(III) hydroxide center. Screens of the NCI-60 human tumor cell lines reveal that arsenoplatin-1 (AP-1), [Pt(µ-NHC(CH3)O)2ClAs(OH)2], the first representative of this novel class of anticancer agents, displays a superior activity profile relative to the parent drugs As2O3 or cisplatin in a majority of cancer cell lines tested. These activity profiles are important because the success of arsenic trioxide in blood cancers (such as APL) has not been seen in solid tumors due to the rapid clearance of arsenous acid from the body. To understand the biological chemistry of these compounds, we evaluated interactions of AP-1 with the two important classes of biomolecules-proteins and DNA. The first structural studies of AP-1 bound to model proteins reveal that platinum(II) binds the Nε of His in a manner that preserves the Pt-As bond. We find that AP-1 readily enters cells and binds to DNA with an intact Pt-As bond (Pt:As ratio of 1). At longer incubation times, however, the Pt:As ratio in DNA samples increases, suggesting that the Pt-As bond breaks and releases the As(OH)2 moiety. We conclude that arsenoplatin-1 has the potential to deliver both Pt and As species to a variety of hematological and solid cancers.

9-ING-41, a small-molecule glycogen synthase kinase-3 inhibitor, is active in neuroblastoma.

Advanced stage neuroblastoma is a very aggressive pediatric cancer with limited treatment options and a high mortality rate. Glycogen synthase kinase-3ß (GSK-3ß) is a potential therapeutic target in neuroblastoma. Using immunohistochemical staining, we observed positive GSK-3ß expression in 67% of human neuroblastomas (34 of 51 cases). Chemically distinct GSK-3 inhibitors (AR-A014418, TDZD-8, and 9-ING-41) suppressed the growth of neuroblastoma cells, whereas 9-ING-41, a clinically relevant small-molecule GSK-3ß inhibitor with broad-spectrum preclinical antitumor activity, being the most potent. Inhibition of GSK-3 resulted in a decreased expression of the antiapoptotic molecule XIAP and an increase in neuroblastoma cell apoptosis. Mouse xenograft studies showed that the combination of clinically relevant doses of CPT-11 and 9-ING-41 led to greater antitumor effect than was observed with either agent alone. These data support the inclusion of patients with advanced neuroblastoma in clinical studies of 9-ING-41, especially in combination with CPT-11.

Targeting melanoma with front-line therapy does not abrogate Nodal-expressing tumor cells.

Metastatic melanoma is a highly aggressive skin cancer with a poor prognosis. It is the leading cause of skin cancer deaths with a median overall survival for advanced-stage metastatic disease of <6 months. Despite advances in the field with conventional and targeted therapies, the heterogeneity of melanoma poses the greatest ongoing challenge, ultimately leading to relapse and progression to a more drug-resistant tumor in most patients. Particularly noteworthy are recent findings, indicating that these therapies exert selective pressure on tumors resulting in the activation of pathways associated with cancer stem cells that are unresponsive to current therapy. Our previous studies have shown how Nodal, an embryonic morphogen of the transforming growth factor-beta superfamily, is one of these critical factors that is reactivated in aggressive melanoma and resistant to conventional chemotherapy, such as dacarbazine. In the current study, we sought to determine whether BRAF inhibitor (BRAFi) therapy targeted Nodal-expressing tumor cells in uniquely matched unresectable stage III and IV melanoma patient samples before and after therapy that preceded their eventual death due to disease. The results demonstrate that BRAFi treatment failed to affect Nodal levels in melanoma tissues. Accompanying experiments in soft agar and in nude mice showed the advantage of using combinatorial treatment with BRAFi plus anti-Nodal monoclonal antibody to suppress tumor growth and metastasis. These data provide a promising new approach using front-line therapy combined with targeting a cancer stem cell-associated molecule-producing a more efficacious response than monotherapy.

α5ß1 integrin signaling mediates oxidized low-density lipoprotein-induced inflammation and early atherosclerosis.

OBJECTIVE: Endothelial cell activation drives early atherosclerotic plaque formation. Both fibronectin deposition and accumulation of oxidized low-density lipoprotein (oxLDL) occur early during atherogenesis, and both are implicated in enhanced endothelial cell activation. However, interplay between these responses has not been established. The objective of our study was to determine whether endothelial matrix composition modulates the inflammatory properties of oxLDL. APPROACH AND RESULTS: We now show that oxLDL-induced nuclear factor-κB activation, proinflammatory gene expression, and monocyte binding are significantly enhanced when endothelial cells are attached to fibronectin compared with basement membrane proteins. This enhanced response does not result from altered oxLDL receptor expression, oxLDL uptake, or reactive oxygen species production, but results from oxLDL-induced activation of the fibronectin-binding integrin α5ß1. Preventing α5ß1 signaling (blocking antibodies, knockout cells) inhibits oxLDL-induced nuclear factor-κB activation and vascular cell adhesion molecule-1 expression. Furthermore, oxLDL drives α5ß1-dependent integrin signaling through the focal adhesion kinase pathway, and focal adhesion kinase inhibition (PF-573228, small interfering RNA) blunts oxLDL-induced nuclear factor-κB activation, vascular cell adhesion molecule-1 expression, and monocyte adhesion. Last, treatment with the α5ß1 signaling inhibitor, ATN-161, significantly blunts atherosclerotic plaque development in apolipoprotein E-deficient mice, characterized by reduced vascular cell adhesion molecule-1 expression and macrophage accumulation without affecting fibrous cap size. CONCLUSIONS: Our data suggest that α5ß1-mediated cross-talk between fibronectin and oxLDL regulates inflammation in early atherogenesis and that therapeutics that inhibit α5 integrins may reduce inflammation without adversely affecting plaque structure.

Biodistribution and in vivo toxicity of aptamer-loaded gold nanostars.

This paper reports an in vivo evaluation of toxicology and biodistribution of a highly anisotropic Au nanoconstruct composed of a gold nanostar (AuNS) core and a ligand shell of a G-quadruplex DNA aptamer AS1411 (Apt) supporting both targeting and therapy capabilities. We examined the toxicity of the nanoconstructs (Apt-AuNS) at four different injected concentrations. At the highest dose tested (48 mg/kg), maximal tolerated dose was not reached. Clinical pathology showed no apparent signs of acute toxicity. Interestingly, the nanoconstructs circulated longer in female rats compared to male rats. In two different tumor models, the biodistribution of Apt-AuNS, especially tumor accumulation, was different. Accumulation of Apt-AuNS was 5 times higher in invasive breast cancer tumors compared to fibrosarcoma tumors. These results provide insight on identifying a tumor model and nanoconstruct for in vivo studies, especially when an in vitro therapeutic response is observed in multiple cancer cell lines. From the clinical editor: This study investigated the toxicity and distribution of aptamer loaded gold nanostars in a rodent model of invasive breast cancer and fibrosarcoma. Acute toxicity was not identified even in the highest studied doses. Fivefold accumulation was demonstrated in the breast cancer model compared to the fibrosarcoma model. Studies like this are critically important in further clarifying the potential therapeutic use of these nanoconstructs, especially when ex vivo effects are clearly demonstrated.

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

BACKGROUND: The receptor for urokinase-type plasminogen activator (uPAR) is associated with cancer development and progression. Within the tumor microenvironment uPAR is expressed by malignant cells as well as tumor-associated stromal cells. However, the contribution of uPAR expression in these stromal cells to malignancy and patient survival in colorectal cancer is still unclear. This study compares the association of uPAR expression in both colorectal tumor-associated stromal cells and neoplastic cells with clinico-pathological characteristics and patient survival using tissue micro arrays (TMA). METHODS: Immunohistochemical staining of uPAR expression was performed on tumor tissue from 262 colorectal cancer patients. Kaplan-Meier, log rank, and uni- and multivariate Cox's regression analyses were used to calculate associations between uPAR expression and patient survival. RESULTS: In the colorectal tumor-associated stromal microenvironment, uPAR is expressed in macrophages, (neoangiogenic) endothelial cells and myofibroblasts. uPAR expression in tumor-associated stromal cells and neoplastic cells (and both combined) were negatively associated with overall survival (OS) and Disease Free Survival (DFS). Uni- and multivariate Cox's regression analysis for combined uPAR expression in tumor-associated stromal and neoplastic cells showed significant and independent negative associations with OS and DFS. Only uPAR expression in tumor-associated stromal cells showed independent significance in the uni- and multivariate analysis for DFS. CONCLUSION: This study demonstrates a significant independent negative association between colorectal cancer patient survival and uPAR expression in especially tumor-associated stromal cells.

Glycogen synthase kinase 3 activity enhances liver inflammation in MASH.

Background & Aims: Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by excessive circulating toxic lipids, hepatic steatosis, and liver inflammation. Monocyte adhesion to liver sinusoidal endothelial cells (LSECs) and transendothelial migration (TEM) are crucial in the inflammatory process. Under lipotoxic stress, LSECs develop a proinflammatory phenotype known as endotheliopathy. However, mediators of endotheliopathy remain unclear. Methods: Primary mouse LSECs isolated from C57BL/6J mice fed chow or MASH-inducing diets rich in fat, fructose, and cholesterol (FFC) were subjected to multi-omics profiling. Mice with established MASH resulting from a choline-deficient high-fat diet (CDHFD) or FFC diet were also treated with two structurally distinct GSK3 inhibitors (LY2090314 and elraglusib [9-ING-41]). Results: Integrated pathway analysis of the mouse LSEC proteome and transcriptome indicated that leukocyte TEM and focal adhesion were the major pathways altered in MASH. Kinome profiling of the LSEC phosphoproteome identified glycogen synthase kinase (GSK)-3ß as the major kinase hub in MASH. GSK3ß-activating phosphorylation was increased in primary human LSECs treated with the toxic lipid palmitate and in human MASH. Palmitate upregulated the expression of C-X-C motif chemokine ligand 2, intracellular adhesion molecule 1, and phosphorylated focal adhesion kinase, via a GSK3-dependent mechanism. Congruently, the adhesive and transendothelial migratory capacities of primary human neutrophils and THP-1 monocytes through the LSEC monolayer under lipotoxic stress were reduced by GSK3 inhibition. Treatment with the GSK3 inhibitors LY2090314 and elraglusib ameliorated liver inflammation, injury, and fibrosis in FFC- and CDHFD-fed mice, respectively. Immunophenotyping using cytometry by mass cytometry by time of flight of intrahepatic leukocytes from CDHFD-fed mice treated with elraglusib showed reduced infiltration of proinflammatory monocyte-derived macrophages and monocyte-derived dendritic cells. Conclusion: GSK3 inhibition attenuates lipotoxicity-induced LSEC endotheliopathy and could serve as a potential therapeutic strategy for treating human MASH. Impact and Implications: LSECs under lipotoxic stress in MASH develop a proinflammatory phenotype known as endotheliopathy, with obscure mediators and functional outcomes. The current study identified GSK3 as the major driver of LSEC endotheliopathy, examined its pathogenic role in myeloid cell-associated liver inflammation, and defined the therapeutic efficacy of pharmacological GSK3 inhibitors in murine MASH. This study provides preclinical data for the future investigation of GSK3 pharmacological inhibitors in human MASH. The results of this study are important to hepatologists, vascular biologists, and investigators studying the mechanisms of inflammatory liver disease and MASH, as well as those interested in drug development.

Phase I Study of Elraglusib (9-ING-41), a Glycogen Synthase Kinase-3ß Inhibitor, as Monotherapy or Combined with Chemotherapy in Patients with Advanced Malignancies.

PURPOSE: The safety, pharmacokinetics, and efficacy of elraglusib, a glycogen synthase kinase-3ß (GSK-3ß) small-molecule inhibitor, as monotherapy or combined with chemotherapy, in patients with relapsed or refractory solid tumors or hematologic malignancies was studied. PATIENTS AND METHODS: Elraglusib (intravenously twice weekly in 3-week cycles) monotherapy dose escalation was followed by dose escalation with eight chemotherapy regimens (gemcitabine, doxorubicin, lomustine, carboplatin, irinotecan, gemcitabine/nab-paclitaxel, paclitaxel/carboplatin, and pemetrexed/carboplatin) in patients previously exposed to the same chemotherapy. RESULTS: Patients received monotherapy (n = 67) or combination therapy (n = 171) elraglusib doses 1 to 15 mg/kg twice weekly. The initial recommended phase II dose (RP2D) of elraglusib was 15 mg/kg twice weekly and was defined, without dose-limiting toxicity observation, due to fluid volumes necessary for drug administration. The RP2D was subsequently reduced to 9.3 mg/kg once weekly to reduce elraglusib-associated central/peripheral vascular access catheter blockages. Other common elraglusib-related adverse events (AE) included transient visual changes and fatigue. Grade ≥3 treatment-emergent AEs occurred in 55.2% and 71.3% of patients on monotherapy and combination therapy, respectively. Part 1 monotherapy (n = 62) and part 2 combination (n = 138) patients were evaluable for response. In part 1, a patient with melanoma had a complete response, and a patient with acute T-cell leukemia/lymphoma had a partial response (PR). In part 2, seven PRs were observed, and the median progression-free survival and overall survival were 2.1 [95% confidence interval (CI), 2-2.6] and 6.9 (95% CI, 5.7-8.4) months, respectively. CONCLUSIONS: Elraglusib had a favorable toxicity profile as monotherapy and combined with chemotherapy and was associated with clinical benefit supporting further clinical evaluation in combination with chemotherapy.

The apparent uPA/PAI-1 paradox in cancer: more than meets the eye.

The expression of several components of the plasminogen-plasmin (P-P) system in tumor tissues has been shown to have prognostic significance in many human cancers, including those of the breast, prostate, lung, brain, ovary, stomach, colon, rectum, oral cavity, kidney, and bone. Mechanisms of action of the individual components have been extensively studied in tumor cells in vitro and in animal models. By interrupting various putative pathways involved in tumor progression in several experimental tumor models in animals, varying degrees of tumor control have been achieved. However, these efforts have thus far not been able to exert any impact in oncologic clinical practice. A possible explanation is our incomplete understanding of the complex involvement of the P-P system and its interactions with other tumorigenic factors. In this article, the role of various members of the P-P system in cancer is reviewed. Proteolysis via the urokinase-type plasminogen activator-plasminogen activation pathway tends to enhance tumor growth and invasion, and its natural inhibitor plasminogen activator inhibitor type 1 may also enhance tumor growth through the inhibition of apoptosis, enhancing cell proliferation and the promotion of angiogenesis. Meaningful drug designs for therapeutic intervention require a thorough understanding of the role of all of the components involved in this complex mechanism of tumor progression.

Elevated PLAUR is observed in the airway epithelium of asthma patients and blocking improves barrier integrity.

BACKGROUND: Expression of the urokinase plasminogen activator receptor (uPAR) is elevated in the airway epithelium in asthma; however, the contribution of uPAR to asthma pathogenesis and scope for therapeutic targeting remains unknown. OBJECTIVES: To determine (i) the expression profile of uPAR in cultured human bronchial epithelial cells (HBEC) from asthma patients, (ii) the relationship between uPAR and the epithelial barrier, including blocking uPAR functions and (iii) the function of different uPAR isoforms. METHODS: uPAR levels in HBECs isolated from asthma patients and cells at air liquid interface (ALI) during differentiation were quantified. Transepithelial electrical resistance or electrical cell impedance sensing was used to relate uPAR levels to barrier properties, including effects of uPAR blocking antibodies. The functional effects of gain of function was determined using transcriptomics, in cells over-expressing membrane (muPAR), soluble cleaved (scuPAR) or soluble spliced (ssuPAR) isoforms. RESULTS: Elevated expression of uPAR was a feature of cultured HBECs from asthma patients, suggesting intrinsic alterations in asthma patient cells. Soluble uPAR levels inversely correlated with barrier properties of the HBEC layer in 2D and ALI. Blocking uPAR-integrin interactions enhanced barrier formation. The gain of function cells showed limited transcriptomic changes. CONCLUSION: This study provides a significant advance in our understanding of the relationship between asthma, uPAR and the epithelial barrier, where elevated circulating uPAR results in a reduced cell barrier, a phenotype prevalent in asthma.

Side-by-Side Comparison of uPAR-Targeting Optical Imaging Antibodies and Antibody Fragments for Fluorescence-Guided Surgery of Solid Tumors.

PURPOSE: Radical resection is paramount for curative oncological surgery. Fluorescence-guided surgery (FGS) aids in intraoperative identification of tumor-positive resection margins. This study aims to assess the feasibility of urokinase plasminogen activator receptor (uPAR) targeting antibody fragments for FGS in a direct comparison with their parent IgG in various relevant in vivo models. PROCEDURES: Humanized anti-uPAR monoclonal antibody MNPR-101 (uIgG) was proteolytically digested into F(ab')2 and Fab fragments named uFab2 and uFab. Surface plasmon resonance (SPR) and cell assays were used to determine in vitro binding before and after fluorescent labeling with IRDye800CW. Mice bearing subcutaneous HT-29 human colonic cancer cells were imaged serially for up to 120 h after fluorescent tracer administration. Imaging characteristics and ex vivo organ biodistribution were further compared in orthotopic pancreatic ductal adenocarcinoma (BxPc-3-luc2), head-and-neck squamous cell carcinoma (OSC-19-luc2-GFP), and peritoneal carcinomatosis (HT29-luc2) models using the clinical Artemis fluorescence imaging system. RESULTS: Unconjugated and conjugated uIgG, uFab2, and uFab specifically recognized uPAR in the nanomolar range as determined by SPR and cell assays. Subcutaneous tumors were clearly identifiable with tumor-to-background ratios (TBRs) > 2 after 72 h for uIgG-800F and 24 h for uFab2-800F and uFab-800F. For the latter two, mean fluorescence intensities (MFIs) dipped below predetermined threshold after 72 h and 36 h, respectively. Tumors were easily identified in the orthotopic models with uIgG-800F consistently having the highest MFIs and uFab2-800F and uFab-800F having similar values. In biodistribution studies, kidney and liver fluorescence approached tumor fluorescence after uIgG-800F administration and surpassed tumor fluorescence after uFab2-800F or uFab-800F administration, resulting in interference in the abdominal orthotopic mouse models. CONCLUSIONS: In a side-by-side comparison, FGS with uPAR-targeting antibody fragments compared with the parent IgG resulted in earlier tumor visualization at the expense of peak fluorescence intensity.

Lipoprotein receptor-related protein 1 regulates collagen 1 expression, proteolysis, and migration in human pleural mesothelial cells.

The low-density lipoprotein receptor-related protein 1 (LRP-1) binds and can internalize a diverse group of ligands, including members of the fibrinolytic pathway, urokinase plasminogen activator (uPA), and its receptor, uPAR. In this study, we characterized the role of LRP-1 in uPAR processing, collagen synthesis, proteolysis, and migration in pleural mesothelial cells (PMCs). When PMCs were treated with the proinflammatory cytokines TNF-α and IL-1ß, LRP-1 significantly decreased at the mRNA and protein levels (70 and 90%, respectively; P < 0.05). Consequently, uPA-mediated uPAR internalization was reduced by 80% in the presence of TNF-α or IL-1ß (P < 0.05). In parallel studies, LRP-1 neutralization with receptor-associated protein (RAP) significantly reduced uPA-dependent uPAR internalization and increased uPAR stability in PMCs. LRP-1-deficient cells demonstrated increased uPAR t(1/2) versus LRP-1-expressing PMCs. uPA enzymatic activity was also increased in LRP-1-deficient and neutralized cells, and RAP potentiated uPA-dependent migration in PMCs. Collagen expression in PMCs was also induced by uPA, and the effect was potentiated in RAP-treated cells. These studies indicate that TNF-α and IL-1ß regulate LRP-1 in PMCs and that LRP-1 thereby contributes to a range of pathophysiologically relevant responses of these cells.

Mesenchymal stromal cells enhance self-assembly of a HUVEC tubular network through uPA-uPAR/VEGFR2/integrin/NOTCH crosstalk.

Endothelial cells (ECs) degrade the extracellular matrix of vessel walls and contact surrounding cells to facilitate migration during angiogenesis, leading to formation of an EC-tubular network (ETN). Mesenchymal stromal cells (MSC) support ETN formation when co-cultured with ECs, but the mechanism is incompletely understood. We examined the role of the urokinase-type plasminogen activator (uPA) system, i.e. the serine protease uPA, its inhibitor PAI-1, receptor uPAR/CD87, clearance by the low-density lipoprotein receptor-related protein (LRP1) and their molecular partners, in the formation of ETNs supported by adipose tissue-derived MSC. Co-culture of human umbilical vein ECs (HUVEC) with MSC increased mRNA expression levels of uPAR, MMP14, VEGFR2, TGFß1, integrin ß3 and Notch pathway components (Notch1 receptor and ligands: Dll1, Dll4, Jag1) in HUVECs and uPA, uPAR, TGFß1, integrin ß3, Jag1, Notch3 receptor in MSC. Inhibition at several steps in the activation process indicates that uPA, uPAR and LRP1 cross-talk with αv-integrins, VEGFR2 and Notch receptors/ligands to mediate ETN formation in HUVEC-MSC co-culture. The urokinase system mediates ETN formation through the coordinated action of uPAR, uPA's catalytic activity, its binding to uPAR and its nuclear translocation. These studies identify potential targets to help control aberrant angiogenesis with minimal impact on healthy vasculature.

Superoxide dismutase 1 (SOD1) is essential for H2O2-mediated oxidation and inactivation of phosphatases in growth factor signaling.

Superoxide dismutase 1 (SOD1) is an abundant copper/zinc enzyme found in the cytoplasm that converts superoxide into hydrogen peroxide and molecular oxygen. Tetrathiomolybdate (ATN-224) has been recently identified as an inhibitor of SOD1 that attenuates FGF-2- and VEGF-mediated phosphorylation of ERK1/2 in endothelial cells. However, the mechanism for this inhibition was not elucidated. Growth factor (GF) signaling elicits an increase in reactive oxygen species (ROS), which inactivates protein tyrosine phosphatases (PTP) by oxidizing an essential cysteine residue in the active site. ATN-224-mediated inhibition of SOD1 in tumor and endothelial cells prevents the formation of sufficiently high levels of H(2)O(2), resulting in the protection of PTPs from H(2)O(2)-mediated oxidation. This, in turn, leads to the inhibition of EGF-, IGF-1-, and FGF-2-mediated phosphorylation of ERK1/2. Pretreatment with exogenous H(2)O(2) or with the phosphatase inhibitor vanadate abrogates the inhibition of ERK1/2 phosphorylation induced by ATN-224 or SOD1 siRNA treatments. Furthermore, ATN-224-mediated SOD1 inhibition causes the down-regulation of the PDGF receptor. SOD1 inhibition also increases the steady-state levels of superoxide, which induces protein oxidation in A431 cells but, surprisingly, does not oxidize phosphatases. Thus, SOD1 inhibition in A431 tumor cells results in both prooxidant effects caused by the increase in the levels of superoxide and antioxidant effects caused by lowering the levels of H(2)O(2). These results identify SOD1 as a master regulator of GF signaling and as a therapeutic target for the inhibition of angiogenesis and tumor growth.

The Landscape of Glycogen Synthase Kinase-3 Beta Genomic Alterations in Cancer.

Glycogen synthase kinase-3ß (GSK-3ß), a serine/threonine kinase, has been implicated in the pathogenesis of many cancers, with involvement in cell-cycle regulation, apoptosis, and immune response. Small-molecule GSK-3ß inhibitors are currently undergoing clinical investigation. Tumor sequencing has revealed genomic alterations in GSK-3ß, yet an assessment of the genomic landscape in malignancies is lacking. This study assessed >100,000 tumors from two databases to analyze GSK-3ß alterations. GSK-3ß expression and immune cell infiltrate data were analyzed across cancer types, and programmed death-ligand 1 (PD-L1) expression was compared between GSK-3ß-mutated and wild-type tumors. GSK-3ß was mutated at a rate of 1%. The majority of mutated residues were in the kinase domain, with frequent mutations occurring in a GSK-3ß substrate binding pocket. Uterine endometrioid carcinoma was the most commonly mutated (4%) tumor, and copy-number variations were most commonly observed in squamous histologies. Significant differences across cancer types for GSK-3ß-mutated tumors were observed for B cells (P = 0.018), monocytes (P = 0.002), dendritic cells (P = 0.005), neutrophils (P = 0.0003), and endothelial cells (P = 0.014). GSK-3ß mRNA expression was highest in melanoma. The frequency of PD-L1 expression was higher among GSK-3ß-mutated tumors compared with wild type in colorectal cancer (P = 0.03), endometrial cancer (P = 0.05), melanoma (P = 0.02), ovarian carcinoma (P = 0.0001), and uterine sarcoma (P = 0.002). Overall, GSK-3ß molecular alterations were detected in approximately 1% of solid tumors, tumors with GSK-3ß mutations displayed a microenvironment with increased infiltration of B cells, and GSK-3ß mutations were associated with increased PD-L1 expression in selected histologies. These results advance the understanding of GSK-3ß complex signaling network interfacing with key pathways involved in carcinogenesis and immune response.

A multimodal molecular imaging approach targeting urokinase plasminogen activator receptor for the diagnosis, resection and surveillance of urothelial cell carcinoma.

With a 5-year recurrence rate of 30-78%, urothelial cell carcinoma (UCC) rates amongst the highest of all solid malignancies. Consequently, after transurethral resection, patients are subjugated to life-long endoscopic surveillance. A multimodal near-infrared (NIR) fluorescence-based imaging strategy can improve diagnosis, resection and surveillance, hence increasing quality of life. METHODS: Expression of urokinase plasminogen activator receptor (uPAR) and epithelial cell adhesion molecule (EpCAM) are determined on paraffin-embedded human UCC using immunohistochemistry and on UCC cell lines by flow cytometry. MNPR-101, a humanised monoclonal antibody targeting uPAR is conjugated to IRDye800CW and binding is validated in vitro using surface plasmon resonance and cell-based binding assays. In vivo NIR fluorescence and photoacoustic three-dimensional (3D) imaging are performed with subcutaneously growing human UM-UC-3luc2 cells in BALB/c-nude mice. The translational potential is confirmed in a metastasising UM-UC-3luc2 orthotopic mouse model. Infliximab-IRDye800CW and rituximab-IRDye800CW are used as controls. RESULTS: UCCs show prominent uPAR expression at the tumour-stroma interface and EpCAM on epithelial cells. uPAR and EpCAM are expressed by 6/7 and 4/7 UCC cell lines, respectively. In vitro, MNPR-101-IRDye800CW has a picomolar affinity for domain 2-3 of uPAR. In vivo fluorescence imaging with MNPR-101-IRDye800CW, specifically delineates both subcutaneous and orthotopic tumours with tumour-to-background ratios reaching as high as 6.8, differing significantly from controls (p < 0.0001). Photoacoustic 3D in depth imaging confirms the homogenous distribution of MNPR-101-IRDye800CW through the tumour. CONCLUSIONS: MNPR-101-IRDye800CW is suitable for multimodal imaging of UCC, awaiting clinical translation.

The urokinase receptor supports tumorigenesis of human malignant pleural mesothelioma cells.

Malignant pleural mesothelioma (MPM) is a lethal neoplasm for which current therapy is unsatisfactory. The urokinase plasminogen activator receptor (uPAR) is associated with increased virulence of many solid neoplasms, but its role in the pathogenesis of MPM is currently unclear. We found that REN human pleural MPM cells expressed 4- to 10-fold more uPAR than MS-1 or M9K MPM cells or MeT5A human pleural mesothelial cells. In a new orthotopic murine model of MPM, we found that the kinetics of REN cell tumorigenesis is accelerated versus MS-1 or M9K cells, and that REN instillates generated larger tumors expressing increased uPAR, were more invasive, and caused earlier mortality. While REN, MS-1, and M9K tumors were all associated with prominent extravascular fibrin deposition, excised REN tumor homogenates were characterized by markedly increased uPAR at both the mRNA and protein levels. REN cells exhibited increased thymidine incorporation, which was attenuated in uPAR-silenced cells (P < 0.01). REN cells traversed three-dimensional fibrin gels while MS-1, M9K, and MeT5A cells did not. uPAR siRNA or uPAR blocking antibodies decreased REN cell migration and invasion, while uPA and fetal bovine serum augmented the effects. Transfection of relatively low uPAR expressing MS-1 cells with uPAR cDNA increased proliferation and migration in vitro and tumor formation in vivo. These observations link overexpression of uPAR to the pathogenesis of MPM, demonstrate that this receptor contributes to accelerated tumor growth in part through interactions with uPA, and suggest that uPAR may be a promising target for therapeutic intervention.

Regulation of urokinase receptor expression by p53: novel role in stabilization of uPAR mRNA.

We found that p53-deficient (p53(-/-)) lung carcinoma (H1299) cells express robust levels of cell surface uPAR and uPAR mRNA. Expression of p53 protein in p53(-/-) cells suppressed basal and urokinase (uPA)-induced cell surface uPAR protein and increased uPAR mRNA degradation. Inhibition of p53 by RNA silencing in Beas2B human airway epithelial cells conversely increased basal as well as uPA-mediated uPAR expression and stabilized uPAR mRNA. Purified p53 protein specifically binds to the uPAR mRNA 3' untranslated region (3'UTR), and endogenous uPAR mRNA associates with p53. The p53 binding region involves a 37-nucleotide uPAR 3'UTR sequence, and insertion of the p53 binding sequence into beta-globin mRNA destabilized beta-globin mRNA. Inhibition of p53 expression in these cells reverses decay of chimeric beta-globin-uPAR mRNA. These observations demonstrate a novel regulatory role for p53 as a uPAR mRNA binding protein that down-regulates uPAR expression, destabilizes uPAR mRNA, and thereby contributes to the viability of human airway epithelial or lung carcinoma cells.

uPAR antibody (huATN-658) and Zometa reduce breast cancer growth and skeletal lesions.

Urokinase plasminogen activator receptor (uPAR) is implicated in tumor growth and metastasis due to its ability to activate latent growth factors, proteases, and different oncogenic signaling pathways upon binding to different ligands. Elevated uPAR expression is correlated with the increased aggressiveness of cancer cells, which led to its credentialing as an attractive diagnostic and therapeutic target in advanced solid cancer. Here, we examine the antitumor effects of a humanized anti-uPAR antibody (huATN-658) alone and in combination with the approved bisphosphonate Zometa (Zoledronic acid) on skeletal lesion through a series of studies in vitro and in vivo. Treatment with huATN-658 or Zometa alone significantly decreased human MDA-MB-231 cell proliferation and invasion in vitro, effects which were more pronounced when huATN-658 was combined with Zometa. In vivo studies demonstrated that huATN-658 treatment significantly reduced MDA-MB-231 primary tumor growth compared with controls. In a model of breast tumor-induced bone disease, huATN-658 and Zometa were equally effective in reducing skeletal lesions. The skeletal lesions were significantly reduced in animals receiving the combination of huATN-658 + Zometa compared with monotherapy treatment. These effects were due to a significant decrease in osteoclastic activity and tumor cell proliferation in the combination treatment group. Transcriptome analysis revealed that combination treatment significantly changes the expression of genes from signaling pathways implicated in tumor progression and bone remodeling. Results from these studies provide a rationale for the continued development of huATN-658 as a monotherapy and in combination with currently approved agents such as Zometa in patients with metastatic breast cancer.