Competitive Inhibition of a Tumour Cell Surface Protease. A Rapid Technique for in Vitro Testing of Selective Targeting Systems

Abstract

The active centre of a protease on the surface of tumour cells can be located by its affinity for an active site - directed inhibitor, 9-amino acridine. Cells which have uninhibited proteases, bind 9-amino acridine and fluoresce in resin sections. The leukaemic rat was used as a model system to provide tumour cells in a well defined location. Drugs when coupled to a ligand (directed to the active centre of the protease) compete for this binding site with 9-amino acridine. Thus, competitive inhibition of the tumour cell surface protease provides a rapid technique for demonstrating the delivery of liganded molecules to the surface of tumour cells in vitro.

Key Words: :

• Protease
• tumour cell
• targeting
• 9-aminoacridine
• guanidinobenzoatase
• mitomycin C