Targeting a cryptic allosteric site of SIRT6 with small-molecule inhibitors that inhibit the migration of pancreatic cancer cells

SIRT6 belongs to the conserved NAD^(+)-dependent deacetylase superfamily and mediates multiple biological and pathological processes.Targeting SIRT6 by allosteric modulators represents a novel direction for therapeutics,which can overcome the selectivity problem caused by the structural similarity of orthosteric sites among deacetylases.Here,developing a reversed allosteric strategy Allo Reverse,we identified a cryptic allosteric site,Pocket Z,which was only induced by the bi-directional allosteric signal triggered upon orthosteric binding of NAD^(+).Based on Pocket Z,we discovered an SIRT6 allosteric inhibitor named JYQ-42.JYQ-42 selectively targets SIRT6 among other histone deacetylases and effectively inhibits SIRT6 deacetylation,with an IC50 of 2.33μmol/L.JYQ-42 significantly suppresses SIRT6-mediated cancer cell migration and pro-inflammatory cytokine production.JYQ-42,to our knowledge,is the most potent and selective allosteric SIRT6 inhibitor.This study provides a novel strategy for allosteric drug design and will help in the challenging development of therapeutic agents that can selectively bind SIRT6.

Targeting RAS phosphorylation in cancer therapy:Mechanisms and modulators

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 w19%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.