Leshchiner, E.S., Parkhitko, A., Bird, G.H., Luccarelli, J., Bellairs, J.A., Escudero, S., Opoku-Nsiah, K., Godes, M., Perrimon, N., Walensky, L.D. (2015). Direct inhibition of oncogenic KRAS by hydrocarbon-stapled SOS1 helices.  Proc. Natl. Acad. Sci. U.S.A. 112(6): 1761--1766.

FBrf0227559

Research paper

Activating mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) underlie the pathogenesis and chemoresistance of ∼30% of all human tumors, yet the development of high-affinity inhibitors that target the broad range of KRAS mutants remains a formidable challenge. Here, we report the development and validation of stabilized alpha helices of son of sevenless 1 (SAH-SOS1) as prototype therapeutics that directly inhibit wild-type and mutant forms of KRAS. SAH-SOS1 peptides bound in a sequence-specific manner to KRAS and its mutants, and dose-responsively blocked nucleotide association. Importantly, this functional binding activity correlated with SAH-SOS1 cytotoxicity in cancer cells expressing wild-type or mutant forms of KRAS. The mechanism of action of SAH-SOS1 peptides was demonstrated by sequence-specific down-regulation of the ERK-MAP kinase phosphosignaling cascade in KRAS-driven cancer cells and in a Drosophila melanogaster model of Ras85D(V12) activation. These studies provide evidence for the potential utility of SAH-SOS1 peptides in neutralizing oncogenic KRAS in human cancer.

PMC4330742 (PMC) (EuropePMC)