Targeted degradation of Werner syndrome helicase (WRN) via ligand-directed covalent hydrophobic tagging

The Werner syndrome RecQ helicase (WRN) has recently emerged as a novel synthetic lethality target for microsatellite instability-high (MSI-H) cancers. However, available WRN inhibitors or degraders is still lacking so far. Particularly, chemically designed probes capable of degrading WRN irrespective of microsatellite status remain unexplored. Herein, we developed an innovative ligand-directed covalent hydrophobic tagging (LdCHT) strategy leveraging a proximity-activated sulfonamide pyrimidine warhead to achieve precise WRN proteolysis. LdCHT 14c demonstrated high selectivity for WRN and induced phenotype-agnostic WRN degradation across MSI-H and microsatellite stability (MSS) cells. Mechanistic studies revealed that 14c covalently conjugates to C727 within the WRN helicase domain, forming an adamantane-tagged adduct that initiates sustained proteasomal degradation. Notably, 14c demonstrated superior efficacy over the parental WRN inhibitor in suppressing MSI-H cell growth and migration by inducing more profound transcriptional regulation. This study presents a first-in-class WRN degrader to interrogate the atypical roles of WRN and expands the covalent hydrophobic tagging toolbox for biomedical applications.