Identification of a farnesol analog as a Ras function inhibitor using both an in vivo Ras activation sensor and a phenotypic screening approach

Exploring the interactions of the RAS family in the human protein network and their potential implications in RAS-directed therapies

RAS proteins are the founding members of the RAS superfamily of GTPases. They are involved in key signaling pathways regulating essential cellular functions such as cell growth and differentiation. As a result, their deregulation by inactivating mutations often results in aberrant cell proliferation and cancer. With the exception of the relatively well-known KRAS, HRAS and NRAS proteins, little is known about how the interactions of the other RAS human paralogs affect cancer evolution and response to treatment. In this study we performed a comprehensive analysis of the relationship between the phylogeny of RAS proteins and their location in the protein interaction network. This analysis was integrated with the structural analysis of conserved positions in available 3D structures of RAS complexes. Our results show that many RAS proteins with divergent sequences are found close together in the human interactome. We found specific conserved amino acid positions in this group that map to the binding sites of RAS with many of their signaling effectors, suggesting that these pairs could share interacting partners. These results underscore the potential relevance of cross-talking in the RAS signaling network, which should be taken into account when considering the inhibitory activity of drugs targeting specific RAS oncoproteins. This study broadens our understanding of the human RAS signaling network and stresses the importance of considering its potential cross-talk in future therapies.

Farnesyltransferase-Mediated Delivery of a Covalent Inhibitor Overcomes Alternative Prenylation to Mislocalize K-Ras

Mutationally activated Ras is one of the most common oncogenic drivers found across all malignancies, and its selective inhibition has long been a goal in both pharma and academia. One of the oldest and most validated methods to inhibit overactive Ras signaling is by interfering with its post-translational processing and subsequent cellular localization. Previous attempts to target Ras processing led to the development of farnesyltransferase inhibitors, which can inhibit H-Ras localization but not K-Ras due to its ability to bypass farnesyltransterase inhibition through alternative prenylation by geranylgeranyltransferase. Here, we present the creation of a neo-substrate for farnesyltransferase that prevents the alternative prenlation by geranylgeranyltransferase and mislocalizes oncogenic K-Ras in cells.