Impact of Tumor-Associated Glycosylation on the Multi-Functionality of TIMP-1(Tissue Inhibitor of Metalloproteinases-1)

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In order to define new targets for cancer therapy, it is necessary to understand the exact role of individual proteins in specific processes of tumor progression and metastasis. Beyond the era of genomics, it is now increasingly appreciated that protein variants resulting from expression from one gene do exhibit a multitude of differential functions (pleiotropism) as a consequence of post-translational modifications. Protein N-glycosylation is the most versatile post-translational modification occurring in a species-specific manner in eukaryotic cells and crucially contributes to the regulation of most diverse tumor-relevant cellular processes, such as signal transduction, immuno-modulation or cell-matrix interactions. Tumor-associated change of the ‘glycome’ of proteins was recently appreciated as crucial ‘Enabling Characteristic’ for the establishment of all hallmarks of cancer. Species- and tumor cell-specificity of the glycome is rather rarely considered in experimental set-ups in mice or in vitro, when recombinant proteins with undefined glycosylation pattern are employed in functional assays. Tissue inhibitor of metalloproteinases-1 (TIMP-1), a secreted multi-functional factor playing important roles in numerous cancer-associated patho-physiological processes, is a glycoprotein displaying specific N-glycosylation patterns under physiological conditions. Glycosylation-modified TIMP-1 from cancer patients exhibits reduced anti-proteolytic activity, thereby mediating pro-tumorigenic effects. In preliminary experiments, we could show that also the non-canonical tetraspanin (CD63)-mediated signaling function of human TIMP-1 is influenced by glycosylation. In the current project, we aim to unravel the impact of glycosylation on the multi-functionality of human TIMP-1. We will evaluate the macro-heterogeneous glycosylation-dependency of binding features, signaling activity, and anti-proteolytic function. Moreover, we aim to identify so-far unknown disease-associated glycosylation patterns of human TIMP-1 by N-glycome analysis in the context of pancreatic cancer. In the future these findings can be exploited for diagnostic and therapeutic approaches and will help to understand the contrary functions of TIMP-1 in cancer progression. The broader significance and conceptual advance of this study on TIMP-1 is that the impact of glycosylation on (multi-) functionality may be translated to other clinically relevant glycoproteins including cytokines and interleukins.