Quantitative proteomic identification of novel, bioactive substrates of matrix metalloproteinase (MMP)-11 and system-wide identification of new proteases involved in breast cancer progression and metastasis

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Rather than just cleaving extracellular matrix as their name suggests, proteolytic enzymes such as matrix metalloproteinases (MMPs) modulate angiogenesis, growth, invasion, metastasis, and phenotypic evolution of cancer cells by the irreversible processing of bioactive proteins and signaling molecules. One member of the MMP family, MMP-11, was first discovered in the reactive stroma of invasive breast carcinoma, and since then in over 200 publications is very strongly correlated with poor patient outcome in breast carcinoma. But despite extensive characterization, MMP-11 has no known natural substrates to account for its pivotal activities in breast cancer. Therefore, I will employ novel, systemwide quantitative proteomic technologies developed in the laboratory of Prof. Christopher Overall to identify and characterize bioactive substrates of MMP-11 in breast carcinogenesis. To understand the role of proteases in breast cancer development and metastasis it is not only important to define the substrate spectrum of an individual protease but also to identify and characterize new proteases involved in these processes. Therefore, in a second project I will determine the protease degradome, that is the expression levels of all proteases in a murine breast cancer model. For this purpose, an oligonucleotide microarray termed the CLIP-CHIPTM comprising all known human and murine proteases, inactive homologues and inhibitors that was designed and made in the host laboratory will be used. Interesting proteases that are highly expressed in cancer or reactive stromal tissues will be analyzed for their spectrum of substrates termed the substrate degradome. These experiments will provide further insight into the role of proteases including matrix metalloproteinases in cancer progression, especially how they modify the activity of drug target substrates and so contribute to drug target validation in breast cancer.