Computational and Structure-Based Development of High Potent Cell-Active Covalent Inhibitor Targeting the Peptidyl-Prolyl Isomerase NIMA-Interacting-1 (Pin1).

The unique proline isomerase peptidyl-prolyl isomerase NIMA-interacting-1 (Pin1) is reported to activate numerous cancer-driving pathways simultaneously, and aberrant Pin1 activation is present in many human cancers. Here, we identified a novel hit compound, , that covalently modified Pin1 at Cys113 with an half-maximal inhibitory concentration (IC) of 1.33 ± 0.07 μM through screening an in-house library. Crystallographic study drove the process of structure-guided optimization and led to the potent inhibitor with an IC of 0.067 ± 0.03 μM. We obtained four co-crystal structures of Pin1 complexed with inhibitors that elucidated the detailed binding mode of the derivatives with Pin1. Interestingly, the co-crystal of Pin1 with obtained by co-crystallization revealed the conformational change of Gln129 induced by the inhibitor. Furthermore, effectively inhibited the proliferation and downregulated the Pin1 substrates in MDA-MB-231 cells. Collectively, we developed a potent covalent inhibitor of Pin1, , which could be an effective probe for studying the functional roles of Pin1.