MICA: Un-jamming the Ras switch - blocking Ras nucleotide exchange and promoting GTP hydrolysis

A protein called Ras has, for many years, been an extremely important therapeutic target in many types of cancers, yet the ability to target Ras with drugs is still elusive. Under normal conditions Ras acts as a switch that turns on and off, regulating major cellular processes such as growth, division and migration. In a high proportion of cancers the Ras switch is broken and remains in a 'on' state causing uncontrolled cellular growth. This process is often a result of Ras mutations causing the protein to avoid the normal regulatory mechanisms which usually turn it off or regulate it being on in the first place. As part of an Innovate feasability grant in collaboration with a company (Tecrea) our group generated reagents, termed Affimers, that blocked Ras function. Interestingly the reagents can either block Ras from being turned on in the first place or specifically target mutant Ras and turn it off. This represents a very exciting development in understanding the ability to specifically target mutant Ras proteins and could aid the design of drugs to mimic the Affimers or be used as drugs per se. However, the aim of this proposal is to determine how the Affimers are inhibiting Ras function, to try improve on this ability by modifying the Affimers and test their ability to modulate Ras function in cells.

We have developed modulators of Ras activity using novel artificial binding proteins, termed Adhirons (or commercially known as Affimer type II). Each Affimer constrains two nine amino acid variable loop regions for molecular recognition and our group has developed very high quality phage display libraries each comprising greater than 10^10 individual clones. Typically, reagents isolated using phage display have low nanomolar binding affinities and tend to bind in protein binding hot spots. In this project we aim to characterise a suite of Affimers already shown to inhibit Ras activity and Ras protein-protein interactions in vitro. Affimers have been isolated from phage display libraries that modulate Ras activation through 1) inhibiting nucleotide exchange caused by SOScat, 2) and promoting hydrolysis of GTP. These reagents will provide new mechanistic insights into the molecular regulation of Ras, providing novel therapeutic strategies to slow Ras-addicted tumour growth, and will develop our basic understanding of Ras biology and function

The ease with which Affimer technology can be developed greatly enhances their utility compared to other technologies. The implications for health and disease and the ability to develop new drugs when applied to humans will be important for industrial beneficiaries through the potential for development of molecules that modulate protein-protein interactions and for other healthcare products including diagnostics. Similarly the development of agriculturally and environmentally important reagents and products can be envisaged and is currently being explored with academic and industrial partners (submitted NERC grant). Hence, we already have an established network of academic partners in numerous Universities and have funding with industry eg Tecrea (Innovate feasability grant), Pfizer (CASE studentship), Fera (CASE studentship) and Avacta Life Sciences (CASE studentship, license agreement). Some of the Affimers generated in our laboratory for Avacta Life Science are available to purchase and we regularly screen targets for Avacta's industrial collaborators and clients. Some of our unpublished results have generated commercial interest and investment in the Affimer brand which recently helped Avacta fund raise for a therapeutic programme, some of which will be fed back into the academic projects at Leeds. This demonstrating our drive to develop impact through the Affimer technology. This porfolio of collaborators is only likely to grow after publication of the ability to modulate oncogenes providing further impact for our research.

The project thus has the potential to make a significant impact on the wider public, and also on the UK economy. Leeds have services focused upon building appropriate relationships with businesses and other external organisations. There are mechanisms in place for protecting and managing intellectual property that may be produced and for assisting in the exploitation of outputs from the research. We have existing links with Avacta Life Sciences in relation to the Affimer Technology through the University of Leeds. The strong interactions with both industrial partners will provide opportunities for exploring technology and reagent deployment, and create further opportunities such as CASE studentships.