Targeting CDK-2 With Novel Indole-Pyrazole Hybrids: Discovery of Potent Anticancer Agents Supported by Mechanistic...

The current study devised and synthesized a novel class of pyrazole derivatives based on indole as possible inhibitors of cyclin-dependent kinase-2 (CDK-2). ¹H NMR, ¹³C NMR, NOESY, HMQC, and elemental analysis were used to confirm the structural integrity of the synthesized compounds. Promising CDK-2 inhibitory activity was observed in biological assays, and numerous compounds exhibited sub-micromolar IC₅₀ values. Compound 5 d outperformed the reference inhibitor Roscovitine (IC₅₀ = 0.716 µM) as the most potent inhibitor (IC₅₀ = 0.536 µM), followed by compound 9 g (IC₅₀ = 0.675 µM). SAR analysis showed that the observed activity was significantly influenced by the electronic nature of the added substituents as well as the orientation of the indole bond, with brominated derivatives exhibiting greater potency. The antiproliferative activity of the most potent compounds against the cancer cell lines HepG2, HCT-116, and MCF-7 was further assessed. In addition to having an enhanced selectivity index for normal MCF-10A cells (SI = 8.00 vs. 4.96 for Roscovitine), compound 5 d had the greatest activity against MCF-7 cells (IC₅₀ = 6.78 µM), surpassing Roscovitine (IC₅₀ = 8.11 µM). According to mechanistic investigations, compound 5 d significantly reduced the S-phase population, markedly promoted apoptosis, and caused G1 and G2/M cell-cycle arrest. Additionally, the consistent binding of compound 5 d within the ATP-binding pocket of CDK-2 was confirmed by molecular docking and molecular dynamics simulations, and attractive drug-like and pharmacokinetic features, similar to those of Roscovitine, were demonstrated by in silico ADMET predictions. All of these results point to compound 5 d as a promising lead scaffold for developing potent CDK-2-targeted anticancer agents.