Novel colchicine conjugate with unusual effect on the microtubules of cancer cells

Abstract

Abstract Colchicine derivative bearing substituted bispidine moiety, namely N-{7-(3,7-Di-(tert-butoxycarbonyl)-1,5-dimethyl-3,7-diazabicyclo[3.3.1]nonan-9-yl)-oxy-7-oxoheptanoyl}-N-deacetylcolchicine, was synthesized and tested for its effect on the net of microtubules (MT) in lung cancer cells A549. The compound induced not only MT depolymerization but stimulated the formation of small tubulin aggregates and long tubulin fibrils localized mainly around nuclei. The assemblies were morphologically different from tubulin clusters induced by structurally related anticancer agent tubuloclustin. The biotests data demonstrate that the depolymerization takes place for both pure tubulin and tubulin in cellulo, while fibrils are formed only in the cells. The research data of structure–activity relationship for several similar colchicine derivatives synthesized in the work give evidence for the proposition that the initial conjugate may interact not only with tubulin and MT in the cells, but also with MT-associated proteins, involved in the process of tubulin polymerization. The ability to affect simultaneously MAP – tubulin interactions opens attractive prospects in the design of novel anticancer agents.