Development of Non-Ethoxypropanoic Acid Type Cryptochrome Inhibitors with Circadian Molecular Clock-Enhancing Activity by Bioisosteric Replacement

Abstract

Circadian dysfunction is closely associated with an increased risk of various diseases. Considering that molecular clock machinery serves as an intrinsic time-keeping system underlying the circadian rhythm of biological processes, the modulation of the molecular clock machinery is an attractive therapeutic target with novel mechanisms of action. Based on the previous structure–activity relationship study of small molecule cryptochrome (CRY) inhibitors possessing an ethoxypropanoic acid moiety, non-ethoxypropanoic acid-type inhibitors have been developed by bioisosteric replacement. They were evaluated as potent and effective enhancers of E-box-mediated transcription, and, in particular, ester 5d and its hydrolysis product 2d exhibited desirable metabolic and pharmacokinetic profiles as promising drug candidates. Compound 2d directly bound to both CRY1 and 2 in surface plasmon resonance analyses, suggesting that the molecular target is CRY. Effects of compound 5d and 2d on suppressive action of CRY1 on CLOCK:BMAL1-activated E-box-LUC reporter activity revealed that both compounds inhibited the negative feedback actions of CRY on CLOCK:BMAL1. Most importantly, compounds 5d and 2d exhibited significant effects on molecular circadian rhythmicity to be considered circadian clock-enhancers, distinct from the previously developed CRY inhibitors possessing an ethoxypropanoic acid moiety.

A methylbenzimidazole derivative regulates mammalian circadian rhythms by targeting Cryptochrome proteins

“…2-ethoxypropanoic acid derivatives target both CRY isoforms and inhibit their repressive function, enhancing E-box-mediated transcription. 46 , 47 Furthermore, a recent study showed that structure-based drug design could be another useful approach to find CRY1 modulators. 48 In order to obtain further insights into the mechanisms of action of these small-molecules, it is necessary to determine the crystal structures in complex with CRY proteins.…”

A methylbenzimidazole derivative regulates mammalian circadian rhythms by targeting Cryptochrome proteins

“…2-ethoxypropanoic acid derivatives target both CRY isoforms and inhibit their repressive function, enhancing E-box-mediated transcription. 46,47 Furthermore, a recent study showed that structure-based drug design could be another useful approach to find CRY1 modulators. 48 In order to obtain further insights into the mechanisms of action of CRY-modulating small molecules, it is necessary to determine complex crystal structures.…”

Structural and Chemical Biology Approaches Reveal Isoform-Selective Mechanisms of Ligand Interactions in Mammalian Cryptochromes

“…KS15 has anti-proliferative effects on breast cancer MCF-7 cells by increasing p53 and Bax gene expression (Chun et al, 2015). Considering that CRY1 and CRY2 have been associated with p53 suppression or degradation in other cancers (Chan et al, 2021;Jia et al, 2021) and that Cry1 and Cry2 knockout in p53 mutant mice reduces cancer risk (Ozturk et al, 2009), KS15, or its derivatives (Jeong et al, 2021) may be efficacious in the treatment of several cancers, in addition to MCF-7 breast cancer. Together, these results identified CRYs as promising targets of small-molecule compounds.…”