Abstract
The pathophysiological functions of the signaling molecules matrix metalloproteinase-14 (MMP-14) and integrin αvβ3 in various types of cancer are believed to derive from their collaborative activity in promoting invasion, metastasis, and angiogenesis, as shown in vitro and in vivo The two effectors act in concert in a cell-specific manner through the localization of pro-MMP-2 to the cell surface, where it is processed to intermediate and matured MMP-2. The matured MMP-2 product is localized to the cell surface via its binding to integrin αvβ3 The MMP-14/MMP-2/integrin αvβ3 axis thus constitutes an attractive putative target for therapeutic interventions, but the development of inhibitors that target this axis remains an unfulfilled task. To address the lack of such multitarget inhibitors, we have established a combinatorial approach that is based on flow cytometry screening of a yeast-displayed N-TIMP2 (N-terminal domain variant of tissue inhibitor of metalloproteinase-2) mutant library. On the basis of this screening, we generated protein monomers and a heterodimer that contain monovalent and bivalent binding epitopes to MMP-14 and integrin αvβ3 Among these proteins, the bi-specific heterodimer, which bound strongly to both MMP-14 and integrin αvβ3, exhibited superior ability to inhibit MMP-2 activation and displayed the highest inhibitory activity in cell-based models of a MMP-14-, MMP-2-, and integrin αvβ3-dependent glioblastoma and of endothelial cell invasiveness and endothelial capillary tube formation. These assays enabled us to show the superiority of the combined target effects of the inhibitors and to investigate separately the role each of the three signaling molecules in various malignant processes.