The Role of Pyruvate Dehydrogenase Kinase in Diabetes and Obesity

The pyruvate dehydrogenase complex (PDC) is an emerging target for the treatment of metabolic syndrome. To maintain a steady-state concentration of adenosine triphosphate during the feed-fast cycle, cells require efficient utilization of fatty acid and glucose, which is controlled by the PDC. The PDC converts pyruvate, coenzyme A (CoA), and oxidized nicotinamide adenine dinucleotide (NAD+) into acetyl-CoA, reduced form of nicotinamide adenine dinucleotide (NADH), and carbon dioxide. The activity of the PDC is up- and down-regulated by pyruvate dehydrogenase kinase and pyruvate dehydrogenase phosphatase, respectively. In addition, pyruvate is a key intermediate of glucose oxidation and an important precursor for the synthesis of glucose, glycerol, fatty acids, and nonessential amino acids.

Prognostic Significance of Glycolytic Metabolic Change Related to HIF-1alpha in Oral Squamous Cell Carcinomas

BACKGROUND: Growing tumors adapt to a hypoxic environment and increase anaerobic glycolysis. This metabolic switch is related to aggressive behavior. We investigated the relationship between glycolytic metabolism biomarkers associated with hypoxia-inducible factor (HIF)-1alpha and prognosis. METHODS: We performed immunohistochemical staining of HIF-1alpha, pyruvate dehydrogenase kinase (PDK) 1 and lactate dehydrogenase (LDH) 5 in 74 patients with oral squamous cell carcinoma (SCC) who had received curative radical resection. RESULTS: High reactivity of HIF-1alpha, PDK 1 and LDH 5 was observed in 29 (39.2%), 32 (43.2%) and 54 (73.0%) patients, respectively. Expression levels of the three biomarkers were significantly correlated. All three markers were highly expressed in 16 (21.6%) patients. Elevated expression of the three markers was associated with increased invasiveness (p = 0.043) and recurrence (p = 0.017) of tumors. In survival analysis, upregulation of the three markers was additionally associated with shorter disease free survival (DFS, p = 0.001) and overall survival (OS, p = 0.002). High expression of all three markers was a strong independent prognostic factor for DFS (p = 0.030) and OS (p = 0.026). CONCLUSIONS: Oral SCC with altered glycolytic metabolism exhibits a more invasive and aggressive phenotype. Our results indicate that glycolytic metabolism biomarkers related to HIF-1alpha may be independent prognostic factors in patients with oral SCC.