Early Cancer Diagnosis- search hard and don’t let go Circulating Tumour Cells (CTCs) are cells from solid tumours which have spread into the blood, including at the earliest stages of the disease. Studying the genetics and behaviour of CTCs is going to have a major impact on choosing the best way to treat cancer, as well as on our understanding of how cancer develops and spreads. Capturing CTCs is difficult because they are very rare and variable. We have dissected the basic molecular interactions involved in magnetic capture of cancer cells. Weak links at each stage between the magnetic particle and the cell mean that often only the highest expressing cells are captured. From this work we have shown how to enable the capture of cancer cells expressing the lowest levels of tumour marker. We are further developing the speed and sensitivity of CTC capture. We are also studying how CTCs can guide us as to why responses to novel cancer therapies succeed or fail (or work only initially).                                Antibody Engineering Studying the limits of cancer cell capture made clear that even the best antibody interactions are not good enough. We are working to develop a new class of antibodies/affibodies that form covalent bonds to endogenous protein targets. Antibodies that never let go of their targets should reduce the detection limit of soluble biomarkers for early diagnosis, as well as helping CTC capture. A New Generation of Protein Interactions- Superglue from bacteria  We have harnessed an amazing feature of the hairs (pili) on the pathogenic bacterium Streptococcus pyogenes. This enabled us to achieve an irreversible isopeptide bond between genetically-encoded protein and peptide partners. This bond is stable over time, at high temperatures, and against the forces in biological systems (blood flow, cell migration, molecular motors). Our latest interaction, SpyTag with SpyCatcher, is the strongest protein interaction yet measured and is starting to be applied around the world for diverse areas of basic research and biotechnology. We are extending the scope of this reaction, to create new possibilities for synthetic biology: • peptide-peptide ligation with SpyLigase • protein tentacles for CTC capture • protein dendrimers for detecting anti-cancer immune responses • cyclised enzymes to produce robust diagnostic devices. Nano-Architectures for Cell Imaging and Stimulation We are re-designing one of the most useful interactions in the biosciences, streptavidin’s love of biotin: • removing cross-linking, with monovalent streptavidin (for single molecule imaging of growth factor receptor trafficking) • surpassing one of the strongest non-covalent interactions in nature, with our traptavidin mutant showing reduced off- rate and increased mechanical strength (tested at the single molecule level with Vincent Moy in Miami and by crash- testing DNA pumps with David Sherratt) • crystallographic analysis of the limits of non-covalent interaction, studying traptavidin and creating Love-Hate ligands • SpyAvidin hubs for bionanotechnology, enabling two ultrastable links from one hub as well as assemblies from 4 to 8 to 20 subunits (maximising T cell activation). Get in contact for further information about any of these projects, or to discuss the possibility of working on other projects in the area of bionanotechnology / cancer biology.
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