Collagen serves as a structural scaffold and a barrier between tissues, and thus collagen catabolism (collagenolysis) is required to be a tightly regulated process in normal physiology. In turn, the destruction or damage of collagen during pathological states plays a role in tumor growth and invasion, cartilage degradation, or atherosclerotic plaque formation and rupture. Only a small number of proteases have been identified capable of efficient processing of triple-helical regions of collagens. Several members of the zinc metalloenzyme family, specifically matrix metalloproteinases (MMPs), possess collagenolytic activity. A mechanistic understanding of the cleavage of intact collagens has been pursued for many years;the results of such studies could lead to the development of truly selective MMP inhibitors. Our laboratory developed triple-helical peptides (THPs) as MMP substrates, with the goal of using these models to dissect collagenolytic behavior and develop selective MMP inhibitors. In the most recent funding period of the present project (04/01/08-present), we have experimentally derived the initial steps of collagenolysis and identified specific residues involved in this process, quantified the roles of specific collagen residues in MMP substrate specificity, and developed selective MMP inhibitors based on secondary binding sites (exosites), and demonstrated the in vivo use of such inhibitors. Our studies also revealed intriguing, unexpected behaviors of collagenolytic MMPs, such as MMPs bind the triple-helix using slightly different orientations, one can use exosite binding THPs to inhibit some, but not all, proteolytic activities for a given enzyme, which could significantly reduce side effects, and substrate selectivity seen for single-stranded peptides is not observed in the triple-helix. The research plan described herein focuses on further development of triple-helical probes for teasing out collagenolytic MMP sequence specificities, identifying selective MMP inhibitors, and advancing the mechanism of collagenolysis. To achieve these goals we propose to (a) identify THP sequence preferences for the MMP family utilizing positional scanning combinatorial libraries, (b) design and characterize MMP selective, homotrimeric and heterotrimeric triple-helical transition-state analog inhibitors, and (c) explore the latter steps of collagenolysis usin state-of-the-art NMR spectroscopic techniques and design exosite binding THPs. Select inhibitors will be tested in mouse models of breast carcinoma and melanoma. Ultimately, we would like to obtain inhibitors that target those proteases implicated in cancers such as melanoma and breast carcinoma (MMP-1, MMP-2, MMP-9, MMP-13, and MT1-MMP) while sparing proteases with host-beneficial functions (MMP-3 and MMP-8).

Public Health Relevance

The present study is designed to create a novel class of therapeutic agents to selectively stop the action of tumor-associated enzymes that degrade proteins (proteases). These proteases have been shown to be important for cancer progression, and thus blocking their function will impair the spread of cancer.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Drug Discovery and Molecular Pharmacology Study Section (DMP)
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Knowlton, John R
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Torrey Pines Institute for Molecular Studies
Port Saint Lucie
United States
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Zhang, Xuan; Bresee, Jamee; Fields, Gregg B et al. (2014) Near-infrared triple-helical peptide with quenched fluorophores for optical imaging of MMP-2 and MMP-9 proteolytic activity in vivo. Bioorg Med Chem Lett 24:3786-90
Tokmina-Roszyk, Michal; Tokmina-Roszyk, Dorota; Bhowmick, Manishabrata et al. (2014) Development of a Förster resonance energy transfer assay for monitoring bacterial collagenase triple-helical peptidase activity. Anal Biochem 453:61-9
Wang, Hongjie; Nefzi, Adel; Fields, Gregg B et al. (2014) AlphaLISA-based high-throughput screening assay to measure levels of soluble amyloid precursor protein ?. Anal Biochem 459:24-30
Zhang, Xuan; Bresee, Jamee; Cheney, Philip P et al. (2014) Evaluation of a triple-helical peptide with quenched FluorSophores for optical imaging of MMP-2 and MMP-9 proteolytic activity. Molecules 19:8571-88
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Onwuha-Ekpete, Lillian; Tack, Lisa; Knapinska, Anna et al. (2014) Novel pyrrolidine diketopiperazines selectively inhibit melanoma cells via induction of late-onset apoptosis. J Med Chem 57:1599-608
de Castro Brás, Lisandra E; Cates, Courtney A; DeLeon-Pennell, Kristine Y et al. (2014) Citrate synthase is a novel in vivo matrix metalloproteinase-9 substrate that regulates mitochondrial function in the postmyocardial infarction left ventricle. Antioxid Redox Signal 21:1974-85
Chavaroche, Anais; Cudic, Mare; Giulianotti, Marc et al. (2014) Glycosylation of a disintegrin and metalloprotease 17 affects its activity and inhibition. Anal Biochem 449:68-75
Fields, Gregg B (2013) Interstitial collagen catabolism. J Biol Chem 288:8785-93
Cerofolini, Linda; Fields, Gregg B; Fragai, Marco et al. (2013) Examination of matrix metalloproteinase-1 in solution: a preference for the pre-collagenolysis state. J Biol Chem 288:30659-71

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