CHARACTERIZATION OF A NOVEL, MEMBRANE-BOUND, 80-KDA MATRIX-DEGRADING PROTEASE FROM HUMAN BREAST-CANCER CELLS - MONOCLONAL-ANTIBODY PRODUCTION, ISOLATION, AND LOCALIZATION
Cy. Lin et al., CHARACTERIZATION OF A NOVEL, MEMBRANE-BOUND, 80-KDA MATRIX-DEGRADING PROTEASE FROM HUMAN BREAST-CANCER CELLS - MONOCLONAL-ANTIBODY PRODUCTION, ISOLATION, AND LOCALIZATION, The Journal of biological chemistry, 272(14), 1997, pp. 9147-9152
A major, apparently novel extracellular matrix-degrading protease was
previously identified and partially isolated from hormone-dependent bu
t not from hormone-independent human breast cancer cells (Shi, Y. E.,
Torri, J., Yieh, L., Wellstein, A., Lippman, M. E., and Dickson, R. B.
(1993) Cancer Res. 53, 1409-1415). Although initially the 80-kDa prot
ease was identified from breast cancer cell-conditioned medium, immuno
fluorescence staining of breast cancer cells with anti-80-kDa protease
monoclonal antibody 21-9 showed that in addition to its detection in
intracellular compartments, the protease was uniformly localized aroun
d periphery of the cells with more intensive staining on the pseudopod
ia and membrane ruffles. A surface biotinylation technique confirmed t
he plasma membrane localization of the protease. In addition, the 80-k
Da protease could not be washed from the membrane fraction of homogeni
zed breast cancer cells with high concentrations of salts or with EDTA
. The 80-kDa protease may noncovalently associate with other protein(s
) to form complexes, the 95- and 110-kDa proteases. Both complexes sho
wed gelatinolytic activity and bore the epitopes recognized by monoclo
nal antibody 21-9. Furthermore, both complexes could be converted to 8
0-kDa forms by boiling in SDS in the absence of reducing agents. Expre
ssion of this novel, integral membrane gelatinase could allow breast c
ancer cells an alternative to other previously described matrix-degrad
ing enzymes for degradation of the extracellular matrix in close proxi
mity to their surfaces.