2-Alkoxycarbonyl-3-arylamino-5-substituted thiophenes as a novel class of antimicrotubule agents: Design, synthesis, cell growth and tubulin polymerization inhibition

• DOI: 10.1016/j.ejmech.2017.11.096
• Publication Date: 2017-12-02T01:02:14Z
• Authors: Romeo Romagnoli; Maria Kimatrai Sa...; Santiago Schiaffi...; Pier Giovanni Bar...; Paola Oliva; Stefania Baraldi; Luisa Carlota Lop...; Andrea Brancale; Salvatore Ferla; Ernest Hamel; Jan Balzarini; Sandra Liekens; Elena Mattiuzzo; Giuseppe Basso; Giampietro Viola
• Keywords: Models, Molecular; Antineoplastic Agents; Apoptosis; Thiophenes; Antiproliferative agents; Colchicine site; Microtubule; Structure-activity relationship; Tubulin polymerization inhibitors; Pharmacology; Drug Discovery3003 Pharmaceutical Science; Organic Chemistry; Antiproliferative agents; Colchicine site; Microtubule; Structure-activity relationship; Tubulin polymerization inhibitors; Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Membrane Potential, Mitochondrial; Mice; Microtubules; Models, Molecular; Molecular Structure; Polymerization; Reactive Oxygen Species; Structure-Activity Relationship; Thiophenes; Tubulin; Tubulin Modulators; Drug Design; Pharmacology; Drug Discovery3003 Pharmaceutical Science; Organic Chemistry; Microtubules; Polymerization; Mice; Structure-Activity Relationship; 03 medical and health sciences; Tubulin; Cell Line, Tumor; Animals; Humans; Cell Proliferation; Membrane Potential, Mitochondrial; 0303 health sciences; Dose-Response Relationship, Drug; Molecular Structure; 540; Tubulin Modulators; 620; 3. Good health; Drug Design; Drug Screening Assays, Antitumor; Reactive Oxygen Species

Microtubules are recognized as crucial components of the mitotic spindle during cell division, and, for this reason, the microtubule system is an attractive target for the development of anticancer agents. Continuing our search strategy for novel tubulin targeting-compounds, a new series of 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)-5-aryl/heteroarylthiophene derivatives was designed, synthesized and demonstrated to act as tubulin polymerization inhibitors at the colchicine site. A structure-activity relationship study on the phenyl at the 5-position of the thiophene ring was performed by introducing a variety of substituents containing electron-releasing and electron-withdrawing groups, with the 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)thiophene scaffold being the minimum structural requirement for activity. Of the tested compounds, derivatives 4a, 4c, 4i and 4k possessed the highest overall potency and displayed high antiproliferative activities at submicromolar concentrations, with IC50 values ranging from 0.13 to 0.84 μM against four different cancer cell lines. Three agents (4a, 4c and 4i) in the present series had similar effects, and these were comparable to those of the reference compound combretastatin A-4 (CA-4) as inhibitors of tubulin assembly. The antitubulin effects correlated with the cytostatic activities and indicate that these compounds inhibit cell growth through inhibition of tubulin polymerization by binding at the colchicine site. Compound 4c, containing the 2'-thienyl ring at the 5-position of the 2-methoxycarbonyl-3-(3',4',5'-trimethoxyanilino)thiophene scaffold, exhibited substantial antiproliferative activity with a mean IC50 value of 140 nM, inhibited tubulin polymerization with an IC50 value of 1.2 μM, similar to that of CA-4 (IC50: 1.1 μM), and induced apoptosis in HeLa cells.