Hypoxia-inducible factor-1α (HIF-1α) constitutes the principal mediator of cellular adaptation to hypoxia in humans. HIF-1α protein level and activity is tightly regulated by the ubiquitin E3 ligase von Hippel-Lindau (VHL). Here, we performed a structure-guided and bioactivity-driven design of new VHL inhibitors. Our iterative and combinatorial strategy focused on chemical variability at the phenylene unit and encompassed further points of diversity. The exploitation of tailored phenylene fragments and the stereoselective installation of the benzylic methyl group provided potent VHL ligands. Three high-resolution structures of VHL-ligand complexes were determined and bioactive conformations of these ligands were explored. The most potent inhibitor (30) exhibited dissociation constants lower than 40 nM, independently determined by fluorescence polarization and surface plasmon resonance and an enhanced cellular potency, as evidenced by its superior ability to induce HIF-1α transcriptional activity. Our work is anticipated to inspire future efforts towards HIF-1α stabilizers and new ligands for proteolysis-targeting chimeras.
Supporting Figures S1-S9. Supporting Tables S1-S2: mean IC50 values obtained from the FP assay; values kon and koff for selected VHL ligands determined by SPR. Supporting Schemes S1-S2: Synthesis of building blocks 41α-ε. 1H and 13C NMR Assignments. 1H and 13C NMR Spectra. LC-MS Traces of Final Compounds. Crystallographic Data for Co-crystal Structures of VCB in Complex with 30, 33, and 37.