Cyanopyridinone- and Cyanopyridine-Based Cancer Cell Pim-1 Inhibitors: Design, Synthesis, Radiolabeling, Biodistribution, and Molecular Modeling Simulation

In this study, two new series of 3-cyanopyridinones (3a-e) and 3-cyanopyridines (4a-e) were synthesized and evaluated for their cytotoxicity and Pim-1 kinase inhibitory activity adopting 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay and in vitro Pim-1 kinase inhibition assay, respectively. Most of the tested compounds revealed promising cytotoxicity against HepG-2, HCT-116, MCF-7, and PC-3 cell lines. Among them, compounds 4c and 4d showed more potent cytotoxicity against the HePG2 cell line with IC₅₀ = 8.02 ± 0.38 and 6.95 ± 0.34 μM, respectively, than that of the reference 5-FU (IC₅₀ = 9.42 ± 0.46 μM). Moreover, compound 4c was more potent against HCT-116 (IC₅₀ = 7.15 ± 0.35 μM) than 5-FU (IC₅₀ = 8.01 ± 0.39 μM), while compound 4d with IC₅₀ = 8.35 ± 0.42 μM displayed comparable activity to that of the reference drug. Furthermore, high cytotoxic activity was manifested by compounds 4c and 4d against MCF-7 and PC3 cell lines. Our results have also indicated that compounds 4b, 4c, and 4d elicited remarkable inhibition of Pim-1 kinase; 4b and 4c showed equipotent inhibitory activity to that of the reference quercetagetin. Meanwhile, 4d displayed IC₅₀ = 0.46 ± 0.02 μM, showed the best inhibitory activity among the tested compounds, and was more potent than quercetagetin (IC₅₀ = 0.56 ± 0.03 μM). For optimization of the results, docking study of the most potent compounds 4c and 4d in the Pim-1 kinase active site was carried out and compared with both quercetagetin and the reported Pim-1 inhibitor A (VRV), and the results were consistent with those of the biological study. Consequently, compounds 4c and 4d are worthy of further investigations toward the discovery of Pim-1 kinase inhibitors as drug candidates for Cancer therapy. Compound 4b was successfully radiolabeled with radioiodine-131, and its biodistribution in Ehrlich ascites carcinoma (EAC)-bearing mice showed more observable uptake in tumor sites, and hence, it can be introduced as a new radiolabeled agent for tumor imaging and therapy.