A Hydrogel Tethered Inhibitor of Matrix Metalloproteinases

1. A Hydrogel Tethered Inhibitor of Matrix Metalloproteinases Yang Cao, Tristan I. Croll, Gary K. Shooter, Zee Upton, Tim R. Dargaville* Tissue Repair and Regeneration Program, Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology (QUT) 60 Musk Av, Kelvin Grove, Brisbane, QLD t.dargaville@qut.edu.au Introduction Matrix metalloproteinases(MMPs) are a family of zinc ion-containing proteolytic peptidases. During tissue repair of wounds they play an important role in the degradation of extracellular matrix (ECM), growth factor activation and immune system regulation. Over expression of several MMPs including MMP-1, 2, 3, 8, 9 and MMP-10, combined with abnormally high levels of activation and/or low expression of TIMPs, may contribute to excessive degradation of connective tissue and formation of chronic ulcers.1 A wide range of MMP inhibitors have been designed in the past due to their initial promise in the treatment of MMP-related diseases such as cancer and their great success in pre- clinical trials using animal models at the early stage of cancer progression. Four major types of MMP inhibitors for cancer treatment that have been clinically evaluated are hydroxamates, carboxylates, thiols and the tetracycline analogs (doxycyclines). These compounds typically inactivate MMPs by chelating or coordinating to the zinc ion in the active site cleft. In this study we explore how a tethered MMP inhibitor might be used to neutralise MMPs over-expressed in chronic wounds. Figure 1 – Docking of the inhibitor with MMP-2 showing chelation of the Zn2+. MMP Inhibition Figure 4 – The inhibitory effect of free inhibitor on active MMPs in solution. Figure 5 – The inhibitory effect of inhibitor-gels on active MMPs. Tethering and Network Formation Figure 2 – Acryl-PEGylation of the inhibitor. Figure 3 – Incorporation of the inhibitor into a PEG gel based on Michael type addtion.3 Aim To develop a scaffold / bandage comprising of a tethered MMP inhibitor for treatment of chronic wounds. • Conclusions • We have designed a new broad spectrum hydroxamic acid-based MMP inhibitor with IC50 values less than 10nM. • Inhibition (albeit diminished) of MMPs has been demonstrated after incorporated into a PEG hydrogel. • Current work is aimed at improving activity after tethering. • Inhibitor Design • Requirements2: • functional group (e.g., carboxylic acid, hydroxamic acid, etc.) capable of chelating the active-site zinc(II) ion • at least one functional group which provides a hydrogen bond interaction with the enzyme backbone • one or more side chains which undergo effective van der Waals interactions with the enzyme sub-sites. References Rayment, E.A., Upton, Z., Shooter, G.K., British J Dermatology 2008, 158, 951; Whittaker, M., Floyd, C.D., Brown, P., Gearing, A.J.H., Chem Rev 1999, 99, 2735; Elbert, D.L., Pratt, A.B., Lutolf, M.P., Halstenberg, S., Hubbell, J.A., J Controlled Release 2001, 76, 11 Acknowledgements: Queensland State Government for Smart State Fellowships for TD and ZU; NHMRC Development Grant 497266; Tissue Therapies Ltd; Dr Simone Rizzi for 8-arm PEG and PEG-SH2 and helpful discussions.