A large-scale screening strategy using induced protein proximity to identify regulators of Wnt signalling in colorectal cancer

• Applicant: Dr. Lucie Wolf
• Subject Area: General Genetics and Functional Genome Biology ; Cell Biology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 533617596

Colorectal cancer is a major contributor to global disease burden and nearly all cases present with activating mutations in the beta-catenin dependent Wnt signalling pathway. Nevertheless, no treatment for diseases with increased Wnt target gene transcription is currently in clinical practice, emphasising the need for novel therapeutic strategies. Recent advancements in targeted protein degradation provided such new approaches with the development of small molecule degraders that induce physical proximity between a Protein Of Interest (POI) and a component of the proteasomal degradation machinery (e.g. an E3 Ubiquitin Ligase), resulting in POI degradation. However, the scope of application of these degraders is limited. This is because only a small number of E3s are being used for protein regulation and a systematic approach to find further candidates, possibly even including alternative protein classes and working mechanisms, is missing. Here, I propose to use the induced-proximity concept in a near proteome-wide screening strategy for beta-catenin activity in colon cancer cells to discover novel regulators of Wnt signalling. To this end, I want to conduct two screens, one for beta-catenin function and one for beta-catenin protein abundance. Hits for follow-up experiments are going to be selected from the overlap of both screens (which potentially regulate beta-catenin by degradation) or from the functional screen alone (potentially regulate beta-catenin through a different mechanism). Both screens combine endogenously green fluorescent protein (GFP)-tagged beta-catenin with an Open Reading Frame (ORF) library allowing targeted recruitment of any GFP-tagged protein into proximity of over 15,000 ORFs. Thus, I aim for a more comprehensive understanding of how the induced proximity concept can be leveraged in the context of cancer and for expanding the toolbox of targeted protein degradation. The overall goal based on these insights is the discovery of novel strategies to target beta-catenin dependent Wnt signalling and to lay the groundwork for novel treatment options for colorectal cancer.

• DFG Programme: WBP Fellowship
• International Connection: Canada
• Host: Professor Dr. Stéphane Angers