High‐affinity urokinase‐derived cyclic peptides inhibiting urokinase/urokinase receptor‐interaction: effects on tumor growth and spread

Sato, Sumito; Kopitz, Charlotte; Schmalix, Wolfgang A.; Muehlenweg, Bernd; Kessler, Horst; Schmitt, Manfred; Krüger, Achim; Magdolen, Viktor

doi:10.1016/s0014-5793(02)03311-2

Cited by 53 publications

(33 citation statements)

References 25 publications

(48 reference statements)

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“…Our model raises the major concern that some small binding antagonists may in fact possess undesirable agonist effects on uPAR-mediated adhesion and migration on vitronectin-rich matrices. This ambiguity of action is illustrated by the inductive effects we observe for AE234, which actually was considered a potential lead compound for pharmaceutical intervention of uPA binding (42,46). Similar concerns are, however, less relevant for compounds belonging to the AE105-derived class of inhibitors.…”

Section: Resultsmentioning

confidence: 93%

Conformational Regulation of Urokinase Receptor Function

Gårdsvoll

Jacobsen

Kriegbaum

et al. 2011

Journal of Biological Chemistry

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The urokinase-type plasminogen activator receptor (uPAR) is a glycolipid-anchored membrane protein with an established role in focalizing uPA-mediated plasminogen activation on cell surfaces. Distinct from this function, uPAR also modulates cell adhesion and migration on vitronectin-rich matrices. Although uPA and vitronectin engage structurally distinct binding sites on uPAR, they nonetheless cooperate functionally, as uPA binding potentiates uPAR-dependent induction of lamellipodia on vitronectin matrices. We now present data advancing the possibility that it is the burial of the ␤-hairpin in uPA per se into the hydrophobic ligand binding cavity of uPAR that modulates the function of this receptor. Based on these data, we now propose a model in which the inherent interdomain mobility in uPAR plays a major role in modulating its function. Particularly one uPAR conformation, which is stabilized by engagement of the ␤-hairpin in uPA, favors the proper assembly of an active, compact receptor structure that stimulates lamellipodia induction on vitronectin. This molecular model has wide implications for drug development targeting uPAR function.Timely controlled cell migration is a decisive factor for a plethora of important biological processes that occur during development and adulthood. Controlled cell migration is thus intimately involved in both maintenance and dynamic remodeling of tissue architectures during, e.g. wound healing and mammary gland development (1). These processes are executed and tightly regulated via a complicated cross-talk between specific cell surface receptors (e.g. integrins) and insoluble protein components deposited in the extracellular matrix. The extracellular matrix is nonetheless thought to play a dual role in regulating cell migration, as it provides both the focal adhesion sites required for cellular traction and opposes migration by generating physical barriers (2, 3). Cell migration in vivo, therefore, requires a coordinated regulation of extracellular matrix proteolysis, adhesion, and signaling (4). The urokinase-type plasminogen activator receptor (uPAR) 2 may allegedly assist a rendezvous between these functions, as it has the potential to exert control at all three levels. Besides being responsible for focalizing uPA-mediated plasminogen activation on cell surfaces (5-7), uPAR also facilitates adherence to vitronectin embedded in the extracellular matrix (8 -10), and as a consequence, it promotes intracellular signaling (4, 11).The glycolipid-anchored uPAR is a modular glycoprotein composed of three homologous Ly6/uPAR-type (LU) protein domain repeats (5, 12). The far majority of proteins belonging to this domain family contain only a single copy of the LU module, as exemplified by the glycolipid-anchored CD59, the extracellular ligand binding domain in the TGF-␤ receptors, and the diverse group of secreted snake venom ␣-neurotoxins (13). In the human genome, five genes are recognized so far to encode proteins with multiple LU domains, and these are all confined to a small ...

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Section: Resultsmentioning

confidence: 93%

Conformational Regulation of Urokinase Receptor Function

Gårdsvoll

Jacobsen

Kriegbaum

et al. 2011

Journal of Biological Chemistry

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“…Synthetic cysteine proteinase inhibitors, selective for cathepsin B, have been shown to significantly reduce the invasiveness of MCF10AT cells (Bervar et al, 2003). Several studies using selective inhibitors of uPA or small, synthetic cyclic, competitive uPA antagonists derived from the binding sites of uPAR resulted in highly significant reduction of tumor burden (Evans et al, 1998;Sato et al, 2002). Very recent studies have also shown that fusion of diphtherotoxin with the ATF-uPA caused a statistically significant regression of glial tumors and was highly potent and selective at killing uPAR expressing glioblastoma cell lines (Vallera et al, 2002).…”

Section: Cathepsin B and Upar Sirna Suppresses Intracranial Tumor Growthmentioning

confidence: 99%

RNAi-mediated inhibition of cathepsin B and uPAR leads to decreased cell invasion, angiogenesis and tumor growth in gliomas

et al. 2004

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RNA interference (RNAi) provides a powerful method for gene silencing in eukaryotic cells, including proliferating mammalian cells. Here, we determined whether RNAi could be utilized to inhibit the expression of proteases implicated in the extracellular matrix degradation, which is characteristic of tumor progression. We have previously shown that antisense stable clones of uPAR and cathepsin B were less invasive and did not form tumors when injected intracranially ex vivo. Since antisense-mediated gene silencing does not completely inhibit the translation of target mRNA and high molar concentrations of antisense molecules are required to achieve gene silencing, we used the RNAi approach to silence uPAR and cathepsin B in this study. We found that the expression of doublestranded RNA leads to the efficient and specific inhibition of endogenous uPAR and cathepsin B protein expression in glioma cell lines as determined by Western blotting. We also found the RNAi of uPAR and cathepsin B reduces glioma cell invasion and angiogenesis in in vitro and in vivo models. Intratumoral injections of plasmid vectors expressing hpRNA for uPAR and cathepsin B resulted in the regression of pre-established intracranial tumors. Further, RNAi for uPAR and cathepsin B inhibited cell proliferation and reduced the levels of pERK and pFAK compared to controls. Taken together, our findings indicate for the first time that RNAi operates in human glioma cells with potential application for cancer gene therapy.

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“…10B,C) (Burgle et al, 1997;Magdolen et al, 2001). These cyclic peptides were able to compete with Sato et al, 2002). Down regulation of uPAR expression has also been achieved in pre-clinical models using anti-sense and gene therapy approaches leading to increased tumor dormancy, suppression of tumor growth and metastasis development (Kook et al, 1994;Li et al, 1998 and1999;Aguirre Ghiso et al, 1999, Mohan et al, 1999.…”

Section: Proteolytic Systems As Therapeutic Targetmentioning

confidence: 99%