Inhibition of prenylated KRAS in a lipid environment

RAS mutations lead to a constitutively active oncogenic protein that signals through multiple effector pathways. We describe a novel coupled biochemical assay that measures activation of the effector BRAF by prenylated KRASG12V in a lipid-dependent manner. Using this assay, we discovered compounds that block biochemical and cellular functions of KRASG12V with low single-digit micromolar potency. We characterized the structural basis for inhibition using NMR methods and showed that the compounds stabilized the inactive conformation of KRASG12V. When assays utilize full-length, prenylated KRAS in a lipid environment, cellular, biophysical, and biochemical potencies were similar, which demonstrates the importance of using biologically relevant constructs and assay conditions. These assays and ligands are valuable tools for further study of KRAS inhibition and drug discovery.