A strategy for the selective imaging and inhibition of MT1-MMP to assess its functional roles in breast cancer invasion and metastasis

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Matrix metallo proteases (MMPs) facilitate tumor cell invasion and angiogenesis by mediating degradation of the extracellular matrix, making them promising anti-cancer drug targets. The family of MMPs consists of 23 members with high structural homology but diverse functions in tumor progression. This high degree of structural homology has made the development of specific inhibitors and other chemical tools to study MMPs challenging. Furthermore, in contrast to serine or cysteine proteases, MMPs do not use a protein bound nucleophile to catalyze cleavage of the amide bond. Thus, they lack a nucleophile that can be targeted by inhibitors to covalently modify the enzyme. The group of Prof. Matthew Bogyo has recently developed a new approach that overcomes these limitations and allows specific targeting of individual MMP proteases. The strategy involves the introduction of a functionally silent mutation into a MMP protease to generate a nucleophile for covalent modification by small molecule inhibitors and optical probes that have been designed to target the newly introduced residue. Thus, probes can be generated to be absolutely selective for the engineered MMP allowing specific imaging and selective inhibition of the desired protease with a high degree of temporal control. In addition this protease engineering/probe approach avoids limitations of previous knock out studies targeting MMPs like issues of compensation and lethality. In this proposal I outline plans to apply this newly developed technology to a mouse model of breast cancer to study the function of membrane type 1-matrix metalloproteinase 1 (MT1-MMP) in cancer progression. MT1-MMP is the most potent collagenase among the MMPs and is critical for cancer cell invasion through stromal collagen matrices. This outstanding role among the collagenases is most likely based on its localization at the cell membrane enabling focused ECM remodeling. However, a more complete understanding of MT1-MMP function and especially the consequences of its specific inhibition will be required to both dissect its specific role in tumorigenesis and to validate it as a relevant drug target. To accomplish this goal I will use mice that underwent CRISPR/Cas based genome editing to express the engineered MT1-MMP crossed with a transgenic model for metastasizing breast cancer. This model combined with an engineered inhibitor will allow me to evaluate the effect of specific MT1-MMP inhibition on tumor progression and metastatic seeding. Furthermore, direct visualization of active MT1-MMP localization by a selective probe during primary tumor development and at metastatic sites will provide insight into its primary function in disease pathology. I believe that with the help of these highly novel and powerful chemical tools, it will be possible to revisit MT1-MMP as a drug target in cancer treatment and provide a better understanding of MT1-MMP function so that more effective treatment strategies can be developed.