Implications of tempol in pyruvate dehydrogenase kinase 3 targeted anticancer therapeutics: Computational, spectroscopic, and calorimetric studies

Protein kinase inhibitors are currently being used as a major therapeutic option to target cancer, diabetes and neurodegenerative diseases. In recent years, pyruvate dehydrogenase kinase 3 (PDK3) has emerged as an attractive drug target for cancer therapy. In the present study, we have discovered tempol as a potent inhibitor of PDK3, adding to the pool of already existing list of kinase inhibitors. Molecular docking study revealed a strong binding affinity of tempol with PDK3. Further, 100 ns all atom molecular dynamics (MD) simulation study provided deeper insights into the structural dynamics and stability of the PDK3-tempol complex. We observed that tempol forms a stable complex with PDK3 without any significant structural alterations. Binding affinity of tempol with PDK3 was measured by fluorescence binding and isothermal titration calorimetry studies. Thermodynamic analysis revealed the hydrogen bonding and van der Waals forces are major players driving the PDK3-tempol interaction making the process seemingly specific. Additionally, kinase inhibition assay suggested significant inhibition of PDK3 by tempol, revealing an excellent inhibitory action of tempol towards PDK3 (IC₅₀ = 5.43 μM). In conclusion, this study establishes tempol as a potent PDK3 inhibitor implicated in therapeutics targeting PDK3-related pathologies.