Tripodal molecular propellers perturb microtubule dynamics: indole acts as a blade and plays a crucial role in anticancer activity

Tubulin Inhibitors Binding to Colchicine-Site: A Review from 2015 to 2019

Due to the three domains of the colchicine-site which is conducive to the combination with small molecule compounds, colchicine-site on the tubulin has become a common target for antitumor drug development, and accordingly, a large number of tubulin inhibitors binding to the colchicine-site have been reported and evaluated over the past years. In this study, tubulin inhibitors targeting the colchicine-site and their application as antitumor agents were reviewed based on the literature from 2015 to 2019. Tubulin inhibitors were classified into ten categories according to the structural features, including colchicine derivatives, CA-4 analogs, chalcone analogs, coumarin analogs, indole hybrids, quinoline and quinazoline analogs, lignan and podophyllotoxin derivatives, phenothiazine analogs, N-heterocycle hybrids and others. Most of them displayed potent antitumor activity, including antiproliferative effects against Multi-Drug-Resistant (MDR) cell lines and antivascular properties, both in vitro and in vivo. In this review, the design, synthesis and the analysis of the structure-activity relationship of tubulin inhibitors targeting the colchicine-site were described in detail. In addition, multi-target inhibitors, anti-MDR compounds, and inhibitors bearing antitumor activity in vivo are further listed in tables to present a clear picture of potent tubulin inhibitors, which could be beneficial for medicinal chemistry researchers.

Structural insights into the design of indole derivatives as tubulin polymerization inhibitors

Microtubules are composed of αβ-tubulin heterodimers, and drugs that interfere with microtubule dynamics are used widely in cancer chemotherapy. Small synthetic molecules with an indole nucleus as a core structure have been identified as microtubule inhibitors and recognized as anticancer agents. However, structural information for the interactions between indole derivatives and tubulin is sparse. Here, we present the 2.55 Å crystal structure of tubulin in complex with the indole derivative D64131. We compare the binding modes of D64131, colchicine, and five other indole derivatives to tubulin. These results reveal the interactions between the indole derivatives and tubulin, explain previous results of structure-activity-relationship (SAR) studies and, thus, provide insights into the development of new indole derivatives targeting the colchicine binding site.