Alexander von Kriegsheim: Network Biology and Proteomics
We have identified multiple likely substrates of the hydroxylases PHD3 (EglN3) and FIH (Hif1AN) and several of these targets cluster in selected signalling pathways. We are currently validating these substrates and delineating the function of the hydroxylations. Our aim is to understand how the hypoxic micro/environment can shape cell fate decisions and survival in the context of cancer.
Regulation of breast cancer invasion and metastasis by ISG15
ISG15 is a small, ubiquitin-like protein modifier. As with ubiquitin, ISG15 can be covalently linked to substrates (ISGylation) through a cascade of E1-E3 ligases. Conversely, ISGylations can be removed by the action of de-isgylation/ubiquitination proteases (DUBs). Prominently ISG15 and ISGylation is upregulated in response to interferon signalling. More recently, a correlation between ISG15 and cancer progression was inferred. We have constructed cellular models of high/low/absent ISGylations and have characterised how these regulated signalling networks and cell biological traits. In addition, we have identified several hundred novel endogenous ISG15 substrates. We are currently integrating these data and validating the results in vivo and vitro as well as creating a mathematical model of the network (in collaboration with Lan Nguyen/Monash University, Melbourne, Australia).
Development of a drug target-deconvolution platform
Phenotypic Drug Discovery (PDD) and biotherapeutics are gaining increasing importance as drug discovery strategies where candidate small molecule drugs, or therapeutic antibodies, are identified by screening in disease-relevant biological assays and are selected based on phenotypic outcome prior to knowledge of drug target. It has been proposed that PDD in disease relevant assays may reduce late stage attrition rates and support the identification and prioritization of novel therapeutic targets for conventional Targeted Drug Discovery (TDD). The critical bottleneck in PDD and novel tAB development is fast and efficient target deconvolution.
Given the importance of identifying drug-target interaction partners, it is not surprising that considerable effort has been invested in establishing platforms that allow the identification of target interactions. In the field of therapeutic antibodies (tABs), target binders can be identified by probing protein or cell microarrays with the tAB. However, both approaches suffer from several limitations. Protein microarrays cannot capture the breadth of antigens present in biological samples as the immobilised proteins are expressed recombinantly. Thus, they typically represent only a fraction of proteins that can be expressed and purified in such fashion.
Given the limitations of these assays, we are now establishing a robust and unbiased assay that will allow determining tAB interactions with endogenous proteins within any biological sample. We are collaborating with MedImmune to test and validate this pipeline.