Targeting RAS phosphorylation in cancer therapy: Mechanisms and modulators

Abstract

RAS, a member of the small GTPase family, functions as a binary switch by shifting between inactive GDP-loaded and active GTP-loaded state. RAS gain-of-function mutations are one of the leading causes in human oncogenesis, accounting for ∼19% of the global cancer burden. As a well-recognized target in malignancy, RAS has been intensively studied in the past decades. Despite the sustained efforts, many failures occurred in the earlier exploration and resulted in an 'undruggable' feature of RAS proteins. Phosphorylation at several residues has been recently determined as regulators for wild-type and mutated RAS proteins. Therefore, the development of RAS inhibitors directly targeting the RAS mutants or towards upstream regulatory kinases supplies a novel direction for tackling the anti-RAS difficulties. A better understanding of RAS phosphorylation can contribute to future therapeutic strategies. In this review, we comprehensively summarized the current advances in RAS phosphorylation and provided mechanistic insights into the signaling transduction of associated pathways. Importantly, the preclinical and clinical success in developing anti-RAS drugs targeting the upstream kinases and potential directions of harnessing allostery to target RAS phosphorylation sites were also discussed.

Keywords: ABL, Abelson; APC, adenomatous polyposis coli; Allostery; CK1, casein kinase 1; CML, chronic myeloid leukemia; ER, endoplasmic reticulum; GAPs, GTPase-activating proteins; GEFs, guanine nucleotide exchange-factors; GSK3, glycogen synthase kinase 3; HVR, hypervariable region; IP3R, inositol trisphosphate receptors; LRP6, lipoprotein-receptor-related protein 6; OMM, outer mitochondrial membrane; PI3K, phosphatidylinositol 3-kinase; PKC, protein kinase C; PPIs, protein−protein interactions; Phosphorylation; Protein kinases; RAS; RIN1, RAB-interacting protein 1; SHP2, SRC homology 2 domain containing phosphatase 2; SOS, Son of Sevenless; STK19, serine/threonine-protein kinase 19; TKIs, tyrosine kinase inhibitors; Undruggable.