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

Proteolysis of extracellular matrix (ECM) and basement membrane is an essential mechanism used by cancer cells for their invasion and metastasis. The ECM proteinases are divided into three groups: metalloproteinases, cysteine proteinases and serine proteinases. The urokinase plasminogen activator (uPA) system is one of the serine proteinase systems involved in ECM degradation. Members of this system, including uPA and its receptor (uPAR), are overexpressed in several malignant tumors. This system plays a major role in adhesion, migration, invasion and metastasis of cancer cells, thus making it an important target for anticancer drug therapy. Several strategies, including the use of antisense oligodeoxynucleotides, ribozymes, DNAzyme, RNAi, uPA inhibitors, soluble uPAR, catalytically inactive uPA fragments, synthetic peptides and synthetic hybrids are under study, as they interfere with the expression and/or activity of uPA or uPAR in tumor cells. Herein, we discuss the various pharmaceutical strategies under investigation to combat the uPA activity in cancer.

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Severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection is the cause of a worldwide pandemic, currently with limited therapeutic options. The spike glycoprotein and envelope protein of SARS-CoV-2, containing disulfide bridges for stabilization, represent an attractive target as they are essential for binding to the ACE2 receptor in host cells present in the nasal mucosa. Bromelain and Acetylcysteine (BromAc) has synergistic action against glycoproteins by breakage of glycosidic linkages and disulfide bonds. We sought to determine the effect of BromAc on the spike and envelope proteins and its potential to reduce infectivity in host cells. Recombinant spike and envelope SARS-CoV-2 proteins were disrupted by BromAc. Spike and envelope protein disulfide bonds were reduced by Acetylcysteine. In in vitro whole virus culture of both wild-type and spike mutants, SARS-CoV-2 demonstrated a concentration-dependent inactivation from BromAc treatment but not from single agents. Clinical testing through nasal administration in patients with early SARS-CoV-2 infection is imminent.

Background: Pseudomyxoma peritonei (PMP) is a rare disease with excess intraperitoneal mucin secretion. Treatment involves laparotomy, cytoreduction and chemotherapy that is very invasive with patients often acquiring numerous compromises. Hence a mucolytic comprising of bromelain and N-acetyl cystein has been developed to solubilise mucin in situ for removal by catherization. Owing to differences in mucin appearance and hardness, dissolution varies. Therefore the current study investigates the inter-mucin physical and chemical characteristics, in order to reformulate an effective mucolytic for all mucin.Method: PMP mucin, from the three categories (soft, semi hard and hard mucin) was solubilised and then various physical characteristics such as turbidity, density, kinematic viscosity were measured. The water content and the density of solid mucin were also determined. This was followed by the determination of sialic acid, glucose, lipid, Thiol (S-S and S-H) content of the samples. Lastly, the distribution of MUC2, MUC5B and MUC5AC was determined using western blot technique.Results: Both turbidity and kinematic viscosity and sialic acid content increased linearly as the hardness of mucin increased. However, density, hydration, protein, glucose, lipid and sulfhydryl and disulphide content decreased linearly as hardness of mucin increased. The distribution ratio of mucins (MUC2:MUC5B:MUC5AC) in soft mucin is 2.25:1.5:1.0, semi hard mucin is 1:1:1 and hard mucin is 3:2:1.Conclusion: The difference in texture and hardness of mucin may be due to cellular content, hydration, glucose, protein, lipids, thiol and MUC distribution. Soft mucin is solely made of glycoprotein whilst the others contained cellular materials.

Abstract. The urokinase-type plasminogen activator receptor (uPAR) has diverse biological functions including roles in proteolysis, cell adhesion and cellular signaling. We identified a heat shock protein MRJ (DNAJB6) as a novel uPAR-interacting protein in a yeast two-hybrid screen and confirmed the interaction and co-localization by GST-pull down assays, and co-immunoprecipitation in cells transfected with MRJ. Endogenous interaction between uPAR and MRJ was also detected in breast cancer MDA-MB-231 cells. Deletion mapping demonstrated that the C-terminal region of MRJ is required to mediate its interaction with uPAR. To understand the biological function of the uPAR-MRJ complex, we determined whether MRJ regulated uPAR mediated adhesion to vitronectin in human embryonic kidney (HEK) 293 cells stably transfected with uPAR. After transfection with full length MRJ, there was a 50% increase in cell adhesion compared to the mock transfected control (p<0.01). This increase in adhesion is dependent on the uPAR/full length MRJ interaction as cells transfected with the mutant construct containing only N-terminal region or C-terminal region of MRJ had no increase in cell adhesion. The observed increase in adhesion to vitronectin by MRJ was also blocked by an anti-uPAR domain I antibody suggesting that the induced adhesion is at least in part contributed by uPAR on the cell surface. These data provide a novel mechanism by which uPAR plays a role in cell adhesion to vitronectin. IntroductionUrokinase-type plasminogen activator (uPA) receptor (uPAR) has been implicated in multiple cellular pathways, including proteolysis, cell adhesion and signal transduction. The uPAR protein sequence has three repeats which form three homologous domains with ~90 amino acids each. These have been designated DI, DII and DIII from the N-terminal end (1). These domains are homologous to the CD59/Ly6 family (2) and have two short linker regions between DI and DII, as well as DII and DIII. Cleavage of uPAR by both chymotrypsin and uPA occurs in the linker region between DI and DII at residues 87 and 84, respectively, to result in a cleaved form of uPAR (3). There is also a soluble variant of uPAR that has been found in the media of cell lines and body fluids from cancer patients. This soluble form may be either the full-length receptor or a truncated form DIIDIII (4). Binding of uPA to its receptor can activate signal transduction pathways including the Ras/ERK pathway by a mechanism that requires FAK, Src, and Shc activation and induction of transient c-fos gene expression (5,6). In addition to the binding of uPA, several proteins have been found to be associated with uPAR functions or signalling pathways. These include integrins ß1/2/3, vitronectin, cytokeratins 8/18, EGFR (epidermal growth factor receptor), PDGFR (platelet derived growth factor receptor), LDLR-(low density lipoprotein receptor-) related protein, FPR (FMLP-receptor), UPARAP and G-protein coupled receptors FPRL1 (FMLP-receptor-like protein 1). These interactions with uPAR res...

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