Monoclonal Antibody Preparation and Purification of a Tumor Cell Collagenasestimulatory Factor

Abstract

Tumor cells from several sources produce a factor(s) which stimulates fibroblast collagenase production. Monoclonal antibodies have been raised against the tumor cell collagenase-stimulatory factor from LX-1 human lung carcinoma cells and have been used for purification of the factor from LX-1 cell membranes. These purified preparations stimulated fibroblast collagenase production, and 80% of these preparations contained a single M_r ∼58,000 protein detectable by immunoblotting; the other 20% contained an additional minor component with a molecular weight of 35,000. A single protein with a molecular weight of ∼58,000 was also detected in radiolabeled preparations of the purified factor by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Conditioned media from LX-1 cells contain several species with molecular weights lower than 58,000 which are immunologically crossreactive with the membrane-derived factor. Immunofluorescence analysis indicates that the tumor cell collagenase-stimulatory factor is distributed on the outer surface of LX-1 cells and is absent from the cell surface of fibroblasts. These and previous results indicate that the factor is present on the tumor cell surface, is released into conditioned media possibly after proteolytic cleavage, and appears to have an important role in inducing collagenolysis of host stroma during tumor invasion.