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Isolation and characterization of cell lines with reduced urokinase binding
1Department of Laboratory Medicine and Pathobiology, St. Michael's Hospital and University of Toronto, Ontario, Canada. lauh@smh.toronto.on.ca
Clinical & Experimental Metastasis
|February 24, 2001
Summary
Mutagenesis of HT-1080 fibrosarcoma cells yielded lines with reduced urokinase (uPA) binding, impacting proteolytic activity and signaling. These cell lines exhibit altered uPA receptor expression and binding characteristics, affecting cellular functions.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Oncology
Background:
- The urokinase plasminogen activator (uPA) system plays a critical role in extracellular matrix degradation and cell signaling.
- Dysregulation of uPA is implicated in various diseases, including cancer progression.
- Understanding the uPA receptor (uPAR) and its interactions is crucial for therapeutic targeting.
Purpose of the Study:
- To generate and characterize fibrosarcoma cell lines with altered urokinase (uPA) binding.
- To investigate the impact of reduced uPA binding on cellular proteolytic activity and signaling pathways.
- To analyze changes in the expression and binding properties of the uPA receptor.
Main Methods:
- Mutagenesis of HT-1080 fibrosarcoma cells followed by selection for reduced uPA binding.
- Limited dilution cloning to isolate single-cell clones.
- Assays for uPA binding, surface proteolytic activity, plasminogen activation, and MAP kinase activation.
- Immunoblotting and chemical cross-linking to analyze uPA receptor protein species.
- Equilibrium binding experiments to characterize uPA binding sites.
Main Results:
- Six HT-1080 cell lines with 10-65% reduced uPA binding were generated.
- These cell lines exhibited decreased surface-bound uPA activity and plasminogen activation.
- Reduced activation of MAP kinases by uPA was observed in some cell lines.
- Alterations in the proportion of uPA receptor protein species (53 kDa and 38 kDa) were detected.
- Equilibrium binding revealed changes in uPA binding site affinity and number.
Conclusions:
- Mutagenesis can effectively generate fibrosarcoma cell lines with modified uPA binding characteristics.
- Reduced uPA binding correlates with altered proteolytic activity and intracellular signaling.
- Changes in uPA receptor structure and binding properties likely underlie these functional modifications.
- These findings provide insights into the role of the uPA system in fibrosarcoma cell behavior.