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Structural analysis of the interaction between urokinase-type plasminogen activator and its receptor: a potential
M Ploug1, H Gårdsvoll, T J D Jørgensen
1Finsen Laboratory, Strandboulevarden 49, DK-2100 Copenhagen, Denmark. mploug@finsenlab.dk
Abstract:
The ability to degrade the extracellular matrix by controlled proteolysis is an important property of malignant cancer cells, which enables them to invade the surrounding tissue and to gain access to the circulation by intravasation. One proteolytic system thought to be involved in these processes is urokinase-mediated plasminogen activation. Expression of a glycolipid-anchored receptor for urokinase-type plasminogen activator (uPA) targets this system to the cell surface. This receptor (uPAR) is composed of three homologous modules belonging to the Ly-6/uPAR/alpha-neurotoxin protein domain family. Integrity of the three-domain structure of uPAR is required for maintenance of its sub-nanomolar affinity for uPA, but the functional epitope for this interaction is primarily located in uPAR domain I. Using affinity maturation by combinatorial chemistry, we have recently identified a potent 9-mer peptide antagonist of the uPA-uPAR interaction having a high affinity for uPAR (K(d)< 1 nM). Photoaffinity labelling suggests that this peptide interacts with a composite binding site in uPAR involving both domains I and III. When tested in a chicken chorioallantoic membrane assay that was developed to quantify intravasation of human cells, this antagonist was able to reduce the intravasation of HEp-3 cancer cells by approx. 60%.
Insights
A novel peptide antagonist effectively blocks the interaction between urokinase plasminogen activator (uPA) and its receptor (uPAR), significantly reducing cancer cell intravasation by approximately 60%. This discovery offers potential new strategies for inhibiting cancer metastasis.
Area of Science:
- Molecular Biology
- Cancer Research
- Biochemistry
Background:
- Malignant cancer cells degrade the extracellular matrix for invasion and metastasis.
- Urokinase-mediated plasminogen activation is implicated in cancer cell invasion.
- Urokinase plasminogen activator receptor (uPAR) anchors this system to the cell surface.
Purpose of the Study:
- To identify and characterize a potent antagonist of the uPA-uPAR interaction.
- To evaluate the efficacy of this antagonist in reducing cancer cell intravasation.
Main Methods:
- Utilized affinity maturation by combinatorial chemistry to generate a peptide antagonist.
- Employed photoaffinity labeling to determine the binding site of the peptide.
- Assessed antagonist activity using a chicken chorioallantoic membrane assay for cancer cell intravasation.
Main Results:
- A 9-mer peptide antagonist with sub-nanomolar affinity for uPAR was identified.
- The peptide interacts with a composite binding site involving uPAR domains I and III.
- The antagonist reduced HEp-3 cancer cell intravasation by approximately 60%.
Conclusions:
- The identified peptide antagonist effectively inhibits the uPA-uPAR interaction.
- This peptide demonstrates potential as a therapeutic agent to impede cancer cell metastasis.
- Targeting the uPA-uPAR system is a viable strategy for controlling cancer cell invasion.
