Antimetastatic Potential of Quercetin Analogues with Improved Pharmacokinetic Profile: Pharmacoinformatic Preliminary Study

Background: Urokinase-type plasminogen activator (uPA) system is a crucial pathway for tumor invasion and metastasis. Recently, multiple anticancer effects of quercetin have been described, including inhibitory activity against uPA. However, the clinical use of this flavonoid has been limited due to its low oral bioavailability. Objective: The objectives of the study were to assess the antimetastatic potential of quercetin analogues by analyzing their binding affinity for uPA and to select the compounds with improved pharmacological profiles. Methods: Binding affinities of structural analogues of quercetin to uPA receptor were determined by molecular docking analysis using Molegro Virtual Docker software, and molecular descriptors relevant for estimating pharmacological profile were calculated from ligand structures using computational models. Results: Among 44 quercetin analogues, only one quercetin analogue (3,6,2’,4’,5’-pentahydroxyflavone) was found to possess both higher aqueous solubility and membrane permeability, and a stronger affinity for uPA than quercetin, which makes it the potential lead compound for anticancer drug development. Like quercetin, this compound has five hydroxyl groups but is arranged differently, which contributes to the higher aqueous solubility and higher amphiphilic moment compared to quercetin. Since membrane permeability is not recognized as the limiting factor for quercetin absorption, analogues with higher aqueous solubility and retained or stronger uPA inhibitory activity should also be further experimentally validated for potential therapeutic use. Conclusion: Identified quercetin analogues with better physicochemical and pharmacological properties have a high potential to succeed in later stages of research in biological systems as potential anticancer agents with antimetastatic activity.

Moscatilin Inhibits Metastatic Behavior of Human Hepatocellular Carcinoma Cells: A Crucial Role of uPA Suppression via Akt/NF-κB-Dependent Pathway

Hepatocellular carcinoma (HCC) frequently shows early invasion into blood vessels as well as intrahepatic metastasis. Innovations of novel small-molecule agents to block HCC invasion and subsequent metastasis are urgently needed. Moscatilin is a bibenzyl derivative extracted from the stems of a traditional Chinese medicine, orchid Dendrobium loddigesii. Although moscatilin has been reported to suppress tumor angiogenesis and growth, the anti-metastatic property of moscatilin has not been elucidated. The present results revealed that moscatilin inhibited metastatic behavior of HCC cells without cytotoxic fashion in highly invasive human HCC cell lines. Furthermore, moscatilin significantly suppressed the activity of urokinase plasminogen activator (uPA), but not matrix metalloproteinase (MMP)-2 and MMP-9. Interestingly, moscatilin-suppressed uPA activity was through down-regulation the protein level of uPA, and did not impair the uPA receptor and uPA inhibitory molecule (PAI-1) expressions. Meanwhile, the mRNA expression of uPA was inhibited via moscatilin in a concentration-dependent manner. In addition, the expression of phosphorylated Akt, rather than ERK1/2, was inhibited by moscatilin treatment. The expression of phosphor-IκBα, and -p65, as well as κB-luciferase activity were also repressed after moscatilin treatment. Transfection of constitutively active Akt (Myr-Akt) obviously restored the moscatilin-inhibited the activation of NF-κB and uPA, and cancer invasion in HCC cells. Taken together, these results suggest that moscatilin impedes HCC invasion and uPA expression through the Akt/NF-κB signaling pathway. Moscatilin might serve as a potential anti-metastatic agent against the disease progression of human HCC.

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.

Influence of urokinase gene-knockout in C57BL/6-PlautmI. IBugThisPlau6FDhu/GFDhu mice on growth factors in malignant melanoma

Purpose of the study. Studying characteristics of the growth factor dynamics in the intact skin, tumors and perifocal tissues of melanoma in urokinase (uPA) gene-knockout mice.Materials and methods. The study included male and female С57 ВL/6 mice (n=47) and C57BL/6‑Plautm1.1BugThisPlauGFDhu/GFDhu mice with uPA gene-knockout (n=31). В16/F10 melanoma was transplanted subcutaneously at a dose of 0.5 mL (1:10 in normal saline). Intact mice of the same strain served as controls. Levels of VEGFA, VEGFC, sVEGFR1, sVEGFR3, IGF1, IGF2, TGFβ1 and FGF21 were determined by ELISA in the skin, tumor and perifocal tissues isolated on the 21st day of the tumor growth.Results. uPA gene-knockout inhibited the growth (mostly in females) and metastasis (predominantly in males) of melanoma in mice. Inhibition of the migration of malignant cells in males could be due to low levels of TGF-β1 compared to С57 ВL/6 mice: in the skin – by 5.0 times, in tumors – by 1.8 times and in perifocal tissues – by 6.1 times. In uPA gene-knockout females, lower levels of TGF-β1 were observed in tumors – by 1.4 times inhibited metastasis, but not completely, and solitary metastatic foci were registered in the lungs. Нigh levels of IGF1 in tissues of all uPA gene-knockout mice (males: in tumors by 1.4 times, in perifocal tissues by 2.6 times, in the skin by 3.6 times; females: in tumors by 2.6 times, in perifocal tissues by 25.0 times, in the skin by 13.9 times, compared to С57 ВL/6 mice) could maintain the metastatic phenotype of cancer cells (in females) or hiher proliferative activity of melanoma cells (in males). Lower levels of FGF‑21 in tumors (males – by 5.3 times, females – by 18.4 times), perifocal tissues (males – by 9.6 times, females – by 8,5 times) and skin (males – by 6.7 times, females – by 3.3 times) in uPA gene-knockout animals could be due to the IGF‑1 growth, as their reciprocal interaction is known. Interestingly, a significant, although lesser than in mice with a normal genotype, accumulation of VEGFA in melanoma tissues was observed: in males – in tumors by 44.9 times, in perifocal tissues by 6.8 times, in the skin by 2.4 times; in females – in tumors by 5.6 times, in perifocal tissues by 2.6 times, in the skin by 3.3 times, compared to the corresponding intact controls, due to the probable involvement of the uPA receptor (uPAR) in the implementation of VEGF-induced processes.Conclusion. Changing the activity of a system of some growth factors, uPA gene-knockout modifies melanoma metabolism by inhibiting its growth and eliminating or reducing its metastatic activity.

Inhibitory Effects of a Reengineered Anthrax Toxin on Canine Oral Mucosal Melanomas

Canine oral mucosal melanomas (OMM) are the most common oral malignancy in dogs and few treatments are available. Thus, new treatment modalities are needed for this disease. Bacillus anthracis (anthrax) toxin has been reengineered to target tumor cells that express urokinase plasminogen activator (uPA) and metalloproteinases (MMP-2), and has shown antineoplastic effects both, in vitro and in vivo. This study aimed to evaluate the effects of a reengineered anthrax toxin on canine OMM. Five dogs bearing OMM without lung metastasis were included in the clinical study. Tumor tissue was analyzed by immunohistochemistry for expression of uPA, uPA receptor, MMP-2, MT1-MMP and TIMP-2. Animals received either three or six intratumoral injections of the reengineered anthrax toxin prior to surgical tumor excision. OMM samples from the five dogs were positive for all antibodies. After intratumoral treatment, all dogs showed stable disease according to the canine Response Evaluation Criteria in Solid Tumors (cRECIST), and tumors had decreased bleeding. Histopathology has shown necrosis of tumor cells and blood vessel walls after treatment. No significant systemic side effects were noted. In conclusion, the reengineered anthrax toxin exerted inhibitory effects when administered intratumorally, and systemic administration of this toxin is a promising therapy for canine OMM.

uPAR Knockout Results in a Deep Glycolytic and OXPHOS Reprogramming in Melanoma and Colon Carcinoma Cell Lines

Urokinase Plasminogen Activator (uPA) Receptor (uPAR) is a well-known GPI-anchored three-domain membrane protein with pro-tumor roles largely shown in all the malignant tumors where it is over-expressed. Here we have exploited the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 gene knock out approach to investigate its role in the oxidative metabolism in human melanoma and colon cancer as the consequences of its irreversible loss. Knocking out PLAUR, a uPAR-encoding gene, in A375p, A375M6 and HCT116, which are two human melanoma and a colon carcinoma, respectively, we have observed an increased number of mitochondria in the two melanoma cell lines, while we evidenced an immature biogenesis of mitochondria in the colon carcinoma culture. Such biological diversity is, however, reflected in a significant enhancement of the mitochondrial spare respiratory capacity, fueled by an increased expression of GLS2, and in a decreased glycolysis paired with an increased secretion of lactate by all uPAR KO cells. We speculated that this discrepancy might be explained by an impaired ratio between LDHA and LDHB.

Urokinase and its receptor uPAR is a critical component of pulmonary renal cascade and is significant for pulmonary function and contributes to the physiological regulation; relationship with Serpin E2

Many previous studies have shown that induction of uPA, uPA receptor (uPAR), and PAI-1 may occur in lung endothelial cells (ECs) through a uPA-mediated feedback pathway. Soluble urokinase-type plasminogen activator receptor (suPAR) is a soluble form of the urokinase plasminogen activator receptor (uPAR) that is produced upon cleavage of membrane-bound uPAR. It is found in various body fluids, including blood, urine and cerebrospinal fluid. It is now known that Pulmonary function in physiological and patho-physiological condition is regulated by these molecules. On the other hand, Protease nexin-1 or serine protease inhibitor (Serpin E2) is intricately linked in the physiological homeostasis and interacts with uPA system. These are the key elements of the pulmonary renal cascade regulating multiple physiological functions. Key words: Urokinase, suPAR, lungs, SERPIN, physiological, airways