Discovery of Novel Allosteric Eg5 Inhibitors Through Structure‐Based Virtual Screening

Abstract

Mitotic kinesin Eg5 is an attractive anti-cancer drug target. Discovery of Eg5 inhibitors has been focused on targeting the “monastrol-binding site”. However, acquired drug resistance has been reported for such inhibitors. Therefore, identifying new Eg5 inhibitors which function through a different mechanism(s) could complement current drug candidates and improve drug efficacy. In this study, we explored a novel allosteric site of Eg5 and identified new Eg5 inhibitors through structure-based virtual screening. Experiments with the Saturation-Transfer Difference (STD) NMR demonstrated that the identified Eg5 inhibitor SRI35566 binds directly to Eg5 without involving microtubules. Moreover, SRI35566 and its two analogs significantly induced monopolar spindle formation in colorectal cancer HCT116 cells and suppressed cancer cell viability and colony formation. Together, our findings reveal a new allosteric regulation mechanism of Eg5 and a novel drug targeting site for cancer therapy.

Effective Synthesis and Biological Evaluation of Natural and Designed Bis(indolyl)methanes via Taurine-Catalyzed Green Approach

“…In particular, owing to the emergence of specific drug-resistant mutations (D130A and L214A), the therapeutic future of monstrol binding site targeting allosteric inhibitors is uncertain. 64 Interestingly, the synthesized BIM derivatives 3k and 3b also dock at the same monastrol binding site, which is at the interface of α3 helix, α2 helix, and Loop 5 (L5) of the Eg5 motor domain ( Figure 2 A, all panels, and Figure 2 B, leftmost panel). The common 3k and 3b binding sites are approximately 12 and 10 Å away from the nucleotide binding site and catalytic Mg 2+ binding sites of the Eg5 motor domain, respectively.…”

“… 59 − 61 Intriguingly, the synthesized BIM derivatives were found to dock at one of the well-established allosteric inhibitor (monastrol) binding sites of the Eg5 motor domain which also houses two other distinct allosteric inhibitor-binding sites. 62 − 64 The monastrol binding allosteric site offers high target specificity but suffers from the emergence of recently reported drug-resistant mutations (D130A and L214A). 65 Hence, since the discovery of monastrol site targeting resistance, resistant therapeutic leads are in high demand to confront drug-resistant Eg5 mutations.…”

Mechanisms by Which Kinesin-5 Motors Perform Their Multiple Intracellular Functions

“…These inhibitors arrest cells in mitosis, producing characteristic monoastral spindles [108,109,149], and lead to apoptosis in proliferative tissues either by binding to loop 5 or other allosteric sites and inhibiting ATPase activity [30,102,103,111,149,272]. To develop and test promising Eg5 inhibitors, different approaches are used, including in silico drug-design predictive tools that seek to bridge computational modeling with drug design and cancer therapy [259,273,274]. Based on these studies, several kinesin-5 inhibitors are currently in clinical trial [29,[275][276][277].…”

Identification of Potential Inhibitors of Cathepsin‐B using Shape & Pharmacophore‐based Virtual Screening, Molecular Docking and Explicit Water Thermodynamics

“…On the computational side, high throughput docking or virtual screening is an asset when it comes to finding small molecule ligands of proteins . Considerable number of reports does suggest that virtual screening, docking and dynamics combined have been successfully employed for identification of inhibitors against many validated drug targets . Utilizing the co‐crystallized structure of the nitroxoline (a potent, selective and reversible inhibitor of catB) with the active site of catB (PDB id – 3AI8), common hit molecules were identified using pharmacophore based model screening, shape based screening and docking based approach.…”

“…[15][16][17] Considerable number of reports does suggest that virtual screening, docking and dynamics combined have been successfully employed for identification of inhibitors against many validated drug targets. [18][19][20] Utilizing the co-crystallized structure of the nitroxoline (a potent, selective and reversible inhibitor of catB) with the active site of catB (PDB id -3AI8), [4] common hit molecules were identified using pharmacophore based model screening, shape based screening and docking based approach. Further, the catB inhibitor conjugated to a highly biocompatible liposomal nanocarrier can increase the efficacy of these inhibitors.…”