Identification of indole-grafted pyrazolopyrimidine and pyrazolopyridine derivatives as new anti-cancer agents: Synthesis, biological assessments, and molecular modeling insights

In the current medical era, developing new PIM-1 inhibitors stands as a significant approach to cancer management due to the pivotal role of PIM-1 kinase in promoting cell survival, proliferation, and drug resistance in various cancers. This study involved designing and synthesizing new derivatives of pyrazolo[1,5-a]pyrimidines (6a–i) and pyrazolo[3,4-b]pyridines (10a–i) as potential anti-cancer agents targeting PIM-1 kinase. The cytotoxicity was screened on three cancer cell lines: A-549 (lung), PANC-1 (pancreatic), and A-431 (skin), alongside MRC5 normal lung cells to assess selectivity. Several pyrazolo[1,5-a]pyrimidines (6b, 6c, 6g, 6h, and 6i) and pyrazolo[3,4-b]pyridine (10f) demonstrated notable anticancer properties, particularly against A-549 lung cancer cells (IC₅₀ range: 1.28–3.52 μM), also they exhibited significantly lower toxicity towards MRC5 normal cells. Thereafter, the compounds were evaluated for their inhibitory activity against PIM-1 kinase. Notably, 10f, bearing a 4-methoxyphenyl moiety, demonstrated good inhibition of PIM-1 with an IC₅₀ of 0.18 μM. Additionally, 10f induced apoptosis and arrested cell cycle progression in A-549 cells. Molecular docking and dynamics simulations provided insights into the binding interactions and compounds’ stability with PIM-1 kinase. The results highlight these compounds, especially 10f, as promising selective anticancer agents targeting PIM-1 kinase.