A New Recruitable E3 Ligase UHRF1 Supporting Targeted Protein Degradation: A Minimal Azide as a Recruitment Ligand

Targeted protein degradation represents a promising therapeutic strategy, yet its broader application is often limited by the scarcity of usable E3 ligases. Glutathione peroxidase 4 (GPX4) is a key target for inducing ferroptosis, but achieving sustained and potent inhibition remains challenging with conventional enzymatic inhibitors. Herein, we report the first small-molecule GPX4 degraders that incorporate either electrophilic warheads or a minimal azide group as an E3 recruitment ligand. The azide-based degrader DK-5070 effectively drives potent GPX4 degradation, achieving a DC₅₀ of 17.4 nM and a Dmax of 84%, thereby outperforming larger PROTAC-based degraders. Notably, DK‑5070 exhibits potent antitumor activity both in vitro (IC₅₀ = 47.21 nM) and in vivo (TGI = 41.8%), demonstrating significant efficacy as a GPX4 degrader. Mechanistic studies reveal that degradation is mediated through recruitment of the oncogenic E3 ligase UHRF1, which is frequently overexpressed in tumors, underscoring the potential for tumor-specific protein degradation. This demonstrated small-molecule degraders that recruit UHRF1 to facilitate targeted degradation of GPX4. In this system, the azide group functions as a minimal recruitment ligand, thereby expanding the E3 ligase toolbox and offering a promising strategy for targeted cancer therapy.