PLK1-mediated PDHA1 phosphorylation drives metabolic reprogramming in lung cancer.

Although the involvement of polo-like kinase 1 (PLK1) in metabolic reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis has been previously described, the underlying molecular mechanism remains unclear. Pyruvate dehydrogenase (PDH) catalyzes the conversion of pyruvate into acetyl-CoA, the starting material for the tricarboxylic acid (TCA) cycle. In a companion study by Zhang et al., we demonstrated that PLK1 phosphorylation of PDHA1 at threonine 57 (PDHA1-T57) drives its protein degradation via mitophagy activation. Using a stable-isotope resolved metabolomics (SIRM) approach, we now show that PLK1 phosphorylation of PDHA1-T57 results in metabolic reprogramming from OXPHOS to glycolysis. Notably, cells mimicking PDHA1-T57 phosphorylation rely more on the aspartate-malate shuttle than on glucose-derived pyruvate to sustain the TCA cycle. This metabolic shift was also observed in mouse embryonic fibroblasts (MEFs) and transgenic mice conditionally expressing the PDHA1-T57D variant, highlighting the role of PLK1 in metabolic reprogramming in vivo. It is well-established that pyruvate dehydrogenase kinase (PDK)-mediated phosphorylation of PDH leads to its inactivation and that dichloroacetic acid (DCA), a PDK inhibitor, has been investigated in preclinical and early clinical studies as a potential therapeutic agent for lung cancer. We demonstrated that DCA combined with Onvansertib, a PLK1 inhibitor, synergistically inhibits lung tumor growth by enhancing mitochondrial ROS, inhibiting glycolysis, and inducing apoptosis. This study aims to elucidate how PLK1-associated activity drives the metabolic reprogramming from OXPHOS to glycolysis during cellular transformation, thereby contributing to lung carcinogenesis. Our results provide support for a clinical trial to evaluate the efficacy of Onvansertib plus DCA in treating lung cancer.