Publication

Abstract : Objectives: Activation of proMMP-2 by membrane type matrix metalloproteinase-1 (MT1-MMP) requires formation of an activation complex involving the hemopexin-like domain of proMMP-2 (PEX), the carboxyl-terminal domain of TIMP-2 (C-TIMP-2) and MT1-MMP. The goal of these experiments was to demonstrate that excess of extraneous recombinant (r) PEX or rC-TIMP-2 may interrupt the activation complex and therefore inhibit MMP-2 activation. Methods: rC-TIMP-2 and rPEX were expressed in E. coli and purified to homogeneity by Ni3+ affinity chromatography as determined by SDS-PAGE. Human fibrosarcoma (HT1080) and rat osteosarcoma (ROS) cell lines were co-cultured with a concentration range of either purified rC-TIMP-2 or rPEX for 24 hours. The level of activation of proMMP-2 secreted into the culture medium was analyzed by gelatin zymography for relative amounts of latent 66 kDa and activated 59-kDa forms of MMP-2. Gel images were digitized and intensities of the two forms of MMP-2 were quantified.Results: With concanavlin-A induction, the ratio of active:latent MMP-2 was 78.6 in HT1080 and 2.5 in ROS culture media. When treated with 7 μM rC-TIMP-2, these ratios decreased to 2.8 in HT1080 and 0.5 in ROS conditioned media, reflecting 96% and 80% inhibition of proMMP-2 activation for HT1080 and ROS cells, respectively. Addition of 2.2 μM rPEX decreased the ratio to 1.5 and 0.22 for HT1080 and ROS, respectively, corresponding to 98% and 91% inhibition of proMMP-2 activation. The inhibition of proMMP-2 activation by rC-TIMP-2 and rPEX was concentration dependent.Conclusion: These results showed that rC-TIMP-2 and rPEX can inhibit activation of proMMP-2 in cancer cells by a mechanism that most likely involves competitive interruption of the interactions between PEX and TIMP-2. This approach constitutes a potential future strategy for MMP-2 inhibition in periodontal disease and oral cancer. (Supported by DE 017139 (COSTAR), DE 018135 and DE 017139).