Design, synthesis, and bioevaluation of diarylpyrimidine derivatives as novel microtubule destabilizers

Abstract

In this work, a series of new diarylpyrimidine derivatives as microtubule destabilizers were designed, synthesized, and evaluated for anticancer activities. Based on restriction configuration strategy, we introduced the pyrimidine moiety containing the hydrogen-bond acceptors as cis-olefin bond of CA-4 analogs to improve structural stability. Compounds 11a-t exerted antiproliferative activities against three human cancer cell lines (SGC-7901, HeLa, and MCF-7), due to tubulin polymerization inhibition, showing high selectivity toward cancer cells in comparison with non-tumoral HSF cells, as evidenced by MTT assays. In mechanistic investigations, compound 11s remarkably inhibited tubulin polymerization and disorganized microtubule in SGC-7901 cells by binding to tubulin. Moreover, 11s caused G2/M phase cell cycle arrest in SGC-7901 cells in a concentration-dependent manner. Furthermore, molecular modeling analysis revealed that 11s interacts with tubulin through binding to the colchicine site. In addition, the prediction of physicochemical properties disclosed that 11s conformed well to the Lipinski's rule of five. This work offered a fresh viewpoint for the discovery of new tubulin-targeting anticancer drugs.

Keywords: antiproliferative activity; combretastatin A-4; microtubule destabilizer; molecular docking; pyrimidine.

FIGURE 1

Chemical structures of some microtubule destabilizers.

FIGURE 2

Chemical structures of some pyrimidine-based microtubule destabilizers.

FIGURE 3

The rational design of target compounds.

SCHEME 1

Reagents and conditions (a) POCl₃, NEt₃, reflux; (b) 3,4,5-trimethoxyphenylboric acid, Pd(PPh₃)₄, K₂CO₃, 1,4-dioxane/H₂O, N₂ atmosphere,110°C, M.W.; (c) Substituted phenylboronic acid, Pd(PPh₃)₄, K₂CO₃, 1,4-dioxane/H₂O, N₂ atmosphere,126°C, M.W.

FIGURE 4

Effects of compound 11s on tubulin polymerization.

FIGURE 5

Effects of compound 11s and CA-4, on the cellular microtubule network and microtubule reassemble by immunofluorescence.

FIGURE 6

Effects of compound 11s on cell cycle. SGC-7901 cell lines were treated with compound 11s for 24 h.

FIGURE 7

Analyses of apoptosis induction in SGC-7901 cells. Cells were harvested and stained with Annexin-V/PI for analysis after treatment with different concentrations of compound 11s and control for 48 h. The diverse cell stages were given as live (Q4), early apoptotic (Q3), late apoptotic (Q2), and necrotic cells (Q1).

FIGURE 8

Proposed binding modes for 11s (A, C) in comparison with CA-4 (A, B) at the colchicine site. Carbon atoms are shown in cyan for CA-4 and in magenta for 11s. The residues from the α-tubulin chain are shown in pale yellow, whereas residues from β-tubulin are colored in gray.