New Insights Into Pyridoxal Kinase Inhibitors and Their Antileukemic Effects.

Pyridoxal kinase (PDXK) plays a pivotal role as an essential enzyme in cellular processes. It catalyzes the phosphorylation of pyridoxal, pyridoxamine, and pyridoxine to generate pyridoxal 5'-phosphate (PLP), the bioactive form of vitamin B6. An intriguing link has emerged between elevated expression levels of PDXK and PLP and various types of carcinomas, including leukemia. Leukemic cells have an increased need for vitamin B6 to sustain their survival and rapid growth, highlighting the potential of targeting PDXK-PLP as a promising therapeutic target in cancer treatment. To discover a novel and promising PDXK inhibitor, we conducted a comprehensive screening of compounds derived from both natural sources and drug-like databases. Our approach involved employing structure-based virtual screening and molecular docking techniques to attenuate the phosphorylation of PLP. Among the top six compounds, ZINC095099376 (referred to as C03) emerged as the most potent inhibitor of PDXK, primarily due to its exceptional binding affinity and remarkable specificity for the target protein. Furthermore, our investigation revealed that compound C03 establishes crucial interactions with key residues within the substrate binding site, indicating that it binds at the same site as the co-crystallized ligand. Remarkably, compound C03 inhibited the endogenous PDXK expression, showed anti-proliferative activity, and triggered an intrinsic pathway for apoptosis via the activation of key apoptotic factors in leukemic cells. In summary, these findings strongly indicate that compound C03 holds promise as a novel inhibitor of PDXK, offering the potential for the development of effective treatments for leukemia.