Alkylation potency and protein specificity of aromatic urea derivatives and bioisosteres as potential irreversible antagonists of the colchicine-binding site

• Published in: Bioorganic & medicinal chemistry 2007-07, Vol.15 (13), p.4456-4469
• Main Authors: Fortin, Jessica S., Lacroix, Jacques, Desjardins, Michel, Patenaude, Alexandre, Petitclerc, Éric, C.-Gaudreault, René
• Format: Article
• Language: English
• Subjects: Alkylating agents; Anticancer drugs; Antineoplastic agents; Antineoplastic Agents, Alkylating - chemical synthesis; Antineoplastic Agents, Alkylating - pharmacology; Antitubulin agents; Binding Sites - drug effects; Biological and medical sciences; Blotting, Western; Cell Cycle - drug effects; Cell Line, Tumor; Cell Proliferation - drug effects; Colchicine - metabolism; Colchicine-binding site ligands; General aspects; HT29 Cells; Humans; Indicators and Reagents; Magnetic Resonance Spectroscopy; Medical sciences; N-Aryl 2-amino-oxazoline; Pharmacology. Drug treatments; Phenyl chloroethylurea; Protein Binding; Proteins - chemistry; Proteins - drug effects; Structure-Activity Relationship; Substrate Specificity; Tubulin - drug effects; Tubulin - metabolism; Urea - analogs & derivatives; Urea - chemical synthesis; Urea - pharmacology
• ISSN: 0968-0896; 1464-3391
• DOI: 10.1016/j.bmc.2007.04.028

A number of N-phenyl- N′-(2-chloroethyl)ureas ( CEUs) have been shown to be potent antimitotics through their covalent binding to the colchicine-binding site on intracellular β-tubulin. The present communication aimed to evaluate the role of the electrophilic 2-chloroethyl amino moiety of CEU on cell growth inhibition and the specificity of the drugs as irreversible antagonists of the colchicine-binding site. To that end, several N-phenyl- N′-(2-ethyl)urea ( EU), N-phenyl- N′-(2-chloroethyl)urea ( CEU), N-aryl amino-2-oxazoline ( OXA), and N-phenyl- N′-(2-chloroacetyl)urea ( CAU) derivatives were prepared and tested for their antiproliferative activity, their effect on the cell cycle, and their irreversible binding to β-tubulin. EU derivatives were devoid of antiproliferative activity. CEUs ( 2h– 2i, 2k, 2l, OXA 3e, 3h, 3i, 3k, 3l, tBCEU, and ICEU), OXA ( 3h, 3i, 3k, 3l, tBOXA, and IOXA), and CAU ( 4a– 4m, tBCAU, and ICAU) had GI 50 between 1.7 and 10 μM on three tumor cell lines. Cytotoxic CEU and OXA arrested the cell cycle in G 2/M phase, while the corresponding CAU were not phase specific. Finally, Western blot analysis clearly showed that only CEUs 2h, 2k, 2l, tBCEU, ICEU and OXA 3h, 3i, 3k, 3l, tBOXA ,and IOXA were able to bind irreversibly to the colchicine-binding site. Our results suggest that increasing the potency of the electrophilic moiety of the aromatic ureas enhances their antiproliferative activity but decreases significantly their capacity to covalently bind to the colchicine-binding site.