WX-132-18B, a novel microtubule inhibitor, exhibits promising anti-tumor effects

Abstract

Cancer drug researchers have been seeking microtubule-inhibiting agents (MIAs) with higher bioactivity and lower toxicity than currently marketed drugs. WX-132-18B, a novel structural compound synthesized at our institute, specifically bound to the colchicine-binding site on tubulin rather than the vinblastine site, and concentrationdependently reduced microtubule content via depolymerization. It exhibited the same cellular phenotypic profiles as the classic MIAs (colchicine, vincristine, and taxol), including inducing cell cycle arrest at the G2/M phase, triggering tumor cell apoptosis, promoting nuclear membrane permeability, reducing mitochondrial membrane potential, and disrupting the redox system balance. Importantly, WX- 132-18B displayed more potent in vitro bioactivity (IC50 0.45-0.99 nM) than did the classic MIAs; it inhibited the proliferation of human umbilical vein endothelial cells and seven types of human tumor cells, especially the taxol-resistant breast cancer cells MX-1/T. WX-132-18B also dose-dependently inhibited mice sarcoma, human lung, and gastric cancer xenograft tumors and the formation of tumor blood vessels in mice. In conclusion, WX-132-18B is a novel microtubule-depolymerizing agent that selectively acts on the colchicine-binding site of tubulin and exerts potent in vitro and in vivo anti-tumor effects. These characteristics, along with its anti-angiogenesis and anti-drug resistance properties, make WX-132-18B a promising anti-tumor drug candidate.