Cell Membrane-Associated MT1-MMP Dependent Activation of MMP-2 in SiHa (Human Cervical Cancer) Cells

Abstract

Among the soluble MMPs, MMP-2 (gelatinase A) is particularly important in the invasive property of tumor cells. Cell membrane-associated MMP-2 activation is one of the challenging areas in tumor biology. In the present communication, we studied the membrane dependent activation of MMP-2 in SiHa cells. Activation of pro-MMP-2 by membrane fraction, membrane extract, and live SiHa cells was studied by gelatin zymography. The role of MT1-MMP in MMP-2 activation was studied by incubating SiHa cells and cell membrane fractions with anti-MT1-MMP antibody. Activation of purified pro-MMP-2 by membrane fraction isolated from SiHa cells, by SiHa cell membrane extract and by SiHa cells, pro-MMP-2 from Con A treated HT-1080 conditioned medium by SiHa cells, and pro-MMP-2 from serum free culture medium of SiHa cells and cervical tissue homogenate by SiHa cell membrane fraction was shown by gelatin zymography. SiHa membrane fraction activated only pro-MMP-2 from purified MMP-9/MMP-2 mixture, indicating that the activation is specific for MMP-2. Inhibition of MMP-2 activation in the presence of anti-MT1-MMP antibody strongly indicated that the cell membrane mediated MMP-2 activation is MT1-MMP dependent. Immunocytochemistry of SiHa cells demonstrated expression of MT1-MMP at focal points. Invasion assay showed that invasiveness of anti-MT1-MMP antibody treated SiHa cells through Matrigel was drastically reduced compared to control SiHa cells. Our findings furnish an example of the cell membrane-associated MT1-MMP mediated MMP-2 activation in SiHa cells and suggest that this MT1-MMP mediated MMP-2 activation is of importance in tumor invasion and metastasis. This MT1-MMP mediated MMP-2 activation on tumor cell surface could be a realistic target for managing metastatic diseases.