A class of novel tubulin polymerization inhibitors exert effective anti-tumor activity via mitotic catastrophe

In current work, a class of novel 4,5-dihydro-1H-pyrazole-1-carboxylate derivatives (E01-E28) were designed, synthesized and evaluated. Among them, the most potent compound E24 exhibited comparable activity against a panel of cancer cells (GI₅₀ ranging 0.05-0.98 μM) and tubulin polymerization inhibition (IC₅₀ = 1.49 μM) with reference drug CA-4(P) (GI₅₀ ranging 0.019-0.32 μM, IC₅₀ = 2.18 μM). The following assays indicated that compound E24 disturbed the dynamics of tubulin catastrophe and rescue, which triggered G2/M arrest, leading to ROS accumulation, cleavage of PARP and apoptosis. Molecular dynamics simulation validated that compound E24 could tightly bind into tubulin heterodimers with β Lys 254 and β Cys 241 of tubulin in the docking pose. Metabolic stability and pharmacokinetics parameters were also determined. The half time (t_1/2) displayed species differences in three microsomes. The plasma elimination half-life (t_1/2), peak plasma concentration (C_max), mean retention time (MRT), the area under the curve (AUC_0-∞) and distribution volume (V_z) of E24 after intravenous administration were 0.90 ± 0.22 h, 594.50 ± 97.23 ng/mL, 1.09 ± 0.22 h, 413.67 ± 105.64 ng/mL*h and 5.03 ± 1.82 L/kg, respectively. In HeLa-xenografts, compound E24 exhibited obvious antitumor efficacy via the suppression of tumor growth without weight loss of body or organ. In brief, compound E24 might be a hopeful candidate with excellent properties for oncotherapy as tubulin polymerization inhibitor.