Butterfly Structure: A Privileged Scaffold Targeting Tubulin-Colchicine Binding Site

Angiogenesis and anti-leukaemia activity of novel indole derivatives as potent colchicine binding site inhibitors

The screened compound DYT-1 from our in-house library was taken as a lead (inhibiting tubulin polymerisation: IC₅₀=25.6 µM, anti-angiogenesis in Zebrafish: IC₅₀=38.4 µM, anti-proliferation against K562 and Jurkat: IC₅₀=6.2 and 7.9 µM, respectively). Further investigation of medicinal chemistry conditions yielded compound 29e (inhibiting tubulin polymerisation: IC₅₀=4.8 µM and anti-angiogenesis in Zebrafish: IC₅₀=3.6 µM) based on tubulin and zebrafish assays, which displayed noteworthily nanomolar potency against a variety of leukaemia cell lines (IC₅₀= 0.09–1.22 µM), especially K562 cells where apoptosis was induced. Molecular docking, molecular dynamics (MD) simulation, radioligand binding assay and cellular microtubule networks disruption results showed that 29e stably binds to the tubulin colchicine site. 29e significantly inhibited HUVEC tube formation, migration and invasion in vitro. Anti-angiogenesis in vivo was confirmed by zebrafish xenograft. 29e also prominently blocked K562 cell proliferation and metastasis in blood vessels and surrounding tissues of the zebrafish xenograft model. Together with promising physicochemical property and metabolic stability, 29e could be considered an effective anti-angiogenesis and -leukaemia drug candidate that binds to the tubulin colchicine site.

Discovery of novel tubulin/HDAC dual-targeting inhibitors with strong antitumor and antiangiogenic potency

A novel series of cis-diphenylethene and benzophenone derivatives as tubulin/HDAC dual-targeting inhibitors were designed and synthesized. Among them, compound 28g exhibited the most potent antiproliferative activities against six different human cancer cell lines, 28g could not only inhibited tubulin polymerization, disrupted cellular microtubule networks but also selectively inhibited class IIa HDACs, especially HDAC7 activity. Further molecular docking demonstrated 28g could occupy the binding pockets of tubulin and HDAC7 meanwhile. Cellular mechanism studies revealed that 28g could induce G2/M phase arrest by down-regulated expression of p-cdc2 and cell apoptosis by regulating mitochondrial membrane potential, reactive oxygen species (ROS) levels and apoptosis-related proteins (PARP, Caspase families) in a dose-dependent manner. Importantly, 28g significantly inhibited HUVEC tube formation, proliferation, migration and invasion. The inhibitory effect against angiogenesis in vivo was confirmed by zebrafish xenograft. Furthermore, 28g could effectively suppress the proliferation and metastasis of MGC-803 cells in vitro and in zebrafish xenograft. All above results indicated that 28g can act as a promising antitumor and antiangiogenic agent via targeting tubulin and class IIa HDACs.

Synthesis and biological evaluation of new 2-methoxyestradiol derivatives: Potent inhibitors of angiogenesis and tubulin polymerization

Here, we report the structural optimization of a hit natural compound, 2-ME₂ (2-methoxyestradiol), which exhibited inhibitory activity but low potency on tubulin polymerization, anti- angiogenesis, MCF-7 proliferation and metastasis in vitro and in vivo. A novel series of 3,17-modified and 17-modified analogs of 2-ME₂ were synthesized and investigated for their antiproliferative activity against MCF-7 and another five different human cancer cell lines leading to the discovery of 9i. 9i bind to tubulin colchicine site tightly, inhibited tubulin polymerization and disrupted cellular microtubule networks. Cellular mechanism studies revealed that 9i could induce G2/M phase arrest by down-regulated expression of p-Cdc2, P21 and cell apoptosis by regulating apoptosis-related proteins (Parp, Caspase families) in a dose-dependent manner. Importantly, 9i significantly inhibited HUVEC tube formation, proliferation, migration and invasion. The inhibitory effect against angiogenesis in vivo was confirmed by zebrafish xenograft. Furthermore, 9i could effectively inhibit the proliferation and metastasis of MCF-7 cells in vitro and in zebrafish xenograft. The satisfactory physicochemical property and metabolic stability of 9i further indicated that it can act as a promising and potent anti-angiogenesis, inhibiting proliferation and metastasis of breast cancer agent via targeting tubulin colchicine binding site.