Structural Basis for Inhibition of Eg5 by Dihydropyrimidines: Stereoselectivity of Antimitotic Inhibitors Enastron, Dimethylenastron and Fluorastrol

Abstract

Human kinesin Eg5, which plays an essential role in mitosis by establishing the bipolar spindle, has proven to be an interesting drug target for the development of cancer chemotherapeutics. Here, we report the crystal structures of the Eg5 motor domain complexed with enastron, dimethylenastron, and fluorastrol. By comparing these structures to that of monastrol and mon-97, we identified the main reasons for increased potency of these new inhibitors, namely the better fit of the ligand to the allosteric binding site and the addition of fluorine atoms. We also noticed preferential binding of the S-enantiomer of enastron and dimethylenastron to Eg5, while the R-enantiomer of fluorastrol binds preferentially to Eg5. In addition, we performed a multidrug resistance (MDR) study in cell lines overexpressing P-glycoprotein (Pgp). We showed that one of these inhibitors may have the potential to overcome susceptibility to this efflux pump and hence overcome common resistance associated with tubulin-targeting drugs.

Analysis of the interaction of the Eg5 Loop5 with the nucleotide site

“…The function of L5 remains unresolved. Interest in L5 function has been heightened by X-ray crystallography observations that L5 is involved in the binding of small-molecule, allosteric inhibitors of Eg5 [11, 12, 14, 42]. The specificity of the allosteric inhibitors to kinesin-5 motors and the obligatory involvement of Eg5 in mitosis offer the potential for the development of novel anti-cancer therapies.…”

Synthesis, characterization and biological evaluation of dihydropyrimidine derivatives

“…They also act as inhibitors for the propagation of the malarial parasite (Chiang et al, 2009), calcium channel blocking agents (Manjula et al, 2004;Singh et al, 2009), inhibitor of rho kinase (ROCK1) (Sehon et al, 2008), inhibitor of human kinesin (Eg5) (Kaan et al, 2010) and as anti-HBV agents (Zhu et al, 2010).…”

Synthesis, Characterization and In Vitro Antimicrobial Evaluations of Bis-1,4-dihydropyrimidines

“…Among a wide variety of pyrimidine derivatives, 3,4-dihydropyrimidines-2-(1H)-ones (DHPMs) have attained unprecedented attention due to their therapeutic and pharmaceutical properties such as antimicrobial 1,2 , antitumor 3,4 , antiviral 5 , anti-inflammatory 6,7 , antihypertensive 8,9 , calcium channel blockers 10,11 and antioxidant 12 associated with them make them an interesting moiety and have always attracted a group of researchers. Variations in the basic scaffold of classical Biginelli structure have attracted much attention recently because these structural variations enhance the pharmacological activities of this motif.…”