Design, synthesis, and anti-breast cancer activity evaluation of novel 3-cyanopyridine derivatives as PIM-1 inhibitors

A novel series of cyanopyridines 7a-j were synthesized via a one-pot multicomponent reaction of arylidene 4 with ammonium acetate 5 and respective methylaryl/heterylketones 6a-j in ethanol using vanillin as a natural starting material. Moreover, the regioselective alkylation reaction was studied by the treatment of cyanopyridines 7a-f and 7j with CH₃I in the presence of K₂CO₃ in DMF to afford O-methylcyanopyridines 8a-g (major) and N-methylcyanopyridines 9a-g (minor), whereas bipyridine 7h gave bipyridinium iodide salt 10. All of the designed cyanopyridines were evaluated as anti-breast cancer (MCF-7) cell lines via PIM Kinase inhibitory activity, and the results displayed that some of them showed high activities, especially compounds 7h and 8f, which showed excellent activities against MCF-7 with IC₅₀ values of 1.89 and 1.69 μM, respectively, more potent than the reference drug doxorubicin. Mechanistically, compounds 7h and 8f exhibited strong in vitro PIM-1 kinase inhibitory activity with an IC₅₀ of 0.281 and 0.58 μM, respectively, compared to the reference staurosporine. Moreover, compound 7h arrested the tumor cells at the S phase and caused cell death mainly by inducing early and late apoptosis. Molecular docking studies against PIM-1 revealed good binding modes of the synthesized compound and showed agreement with the biological results.