Immunological characterization of cell-surface and soluble forms of membrane type 1 matrix metalloproteinase in human breast cancer cells and in fibroblasts

• Published in: Molecular carcinogenesis 1998-06, Vol.22 (2), p.84-94
• Main Authors: Li, Hui, Bauzon, Delbert E., Xu, Xinyun, Tschesche, Harald, Cao, Jian, Sang, QingXiang Amy
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; antibody production; Antibody Specificity; Breast Neoplasms - enzymology; Cell Membrane - enzymology; Enzyme Activation; Enzyme Precursors - immunology; Enzyme Precursors - metabolism; Fibroblasts - enzymology; gelatinase A; Gelatinases - immunology; Gelatinases - metabolism; Humans; invasion and metastasis; Isoenzymes - immunology; Isoenzymes - metabolism; matrilysin; Matrix Metalloproteinases, Membrane-Associated; Metalloendopeptidases - immunology; Metalloendopeptidases - metabolism; Molecular Sequence Data; proteinase processing; Solubility; Tumor Cells, Cultured
• ISSN: 0899-1987; 1098-2744
• DOI: 10.1002/(SICI)1098-2744(199806)22:2<84::AID-MC3>3.0.CO;2-K

Membrane type (MT) 1 matrix metalloproteinase (MMP) activates progelatinase A (pro–MMP‐2), a type IV collagenase, on the cell surface of tumors; however, its function in breast cancer progression and metastasis is not fully understood. To examine the expression of MT1‐MMP in breast cancer cells and fibroblasts, a specific rabbit antibody (Ab) directed against a unique synthetic peptide derived from the human MT1‐MMP catalytic domain was produced, purified, and characterized. This Ab is not likely to cross‐react with MT2‐, MT3‐, or MT4‐MMP or any other MMPs. MT1‐MMP expression and pro–MMP‐2 activation were stimulated by concanavalin A in two human breast carcinoma cell lines (BT549 and MDA‐MB‐231) and in normal human fetal‐lung fibroblasts (HFL‐1) and were slightly upregulated by breast cancer cell–fibroblast interactions. Both pro‐MT1‐MMP in plasma membrane (63.4 kDa) and the soluble forms of the enzyme in culture medium (57.6 and 25–30 kDa) were detected by immunoblot analysis, suggesting that cell‐surface MT1‐MMP exhibits an active conformation without the removal of its propeptide domain and that the mature enzyme is shed into the medium. In breast cancer cells, MT1‐MMP and a recombinant catalytic domain of MT1‐MMP were unable to activate pro‐matrilysin, indicating that MT1‐MMP is not a universal activator of all MMPs. MT1‐MMP may play an important role in the invasive growth and spread of breast cancer cells by specifically activating pro–MMP‐2 to cleave the connective‐tissue barrier. Furthermore, use of the specific Ab may aid in the investigation of the role of MT1‐MMP in human tumors. Mol. Carcinog. 22:84–94, 1998. © 1998 Wiley‐Liss, Inc.