Yüksel Öğünç Keçeci1, Zerrin İncesu2. 1. Department of Biochemistry, Faculty of Pharmacy, Anadolu University, Eskisehir, Turkey. yukselogunc@anadolu.edu.tr. 2. Department of Biochemistry, Faculty of Pharmacy, Anadolu University, Eskisehir, Turkey.
Abstract
BACKGROUND: Normal cells produce energy (ATP) through mitochondrial oxidative phosphorylation in the presence of oxygen. However, many of the cancer cells produce energy with accelerated glycolysis and perform lactic acid production even under normoxic conditions called "The Warburg Effect". In this study, human lung carcinoma cells (A549) were incubated in either a normoxic or hypoxic environment containing 5 mM glucose (Glc 5), 25 mM glucose (Glc 25), or 10 mM galactose (OXPHOS/aglycemic), and then the bioenergetic pathway was anaylsed. METHODS AND RESULTS: HIF-1α stabilization of A549 cells with different metabolic conditions in normoxia and hypoxia (1% O2) was determined using the western blot method. After that, L-lactic acid analysis, p-PDH/PDH expression ratio, ATP analysis, and citrate synthase activity experiments were also performed. It was determined that HIF-1α stabilization reached the maximum level at the 4 h. It has been found that glycolytic cells produce approximately five times more lactate than OXPHOS cells under both normoxia and hypoxia conditions and also have a higher p-PDH/PDH ratio. It has been determined that citrate synthase activity in hypoxia of all metabolic conditions is lower than normoxia. It has been determined that Glc 5 and Glc 25 cells have more ATP production under normoxia than Glc 5 and Glc 25 cells in hypoxia. OXPHOS cells have showed more ATP production in hypoxia. CONCLUSION: It has been determined that oxidative phosphorylation became functional in a hypoxic aglycemic environment despite the metabolic programming regulated by HIF-1α. This data is important in determining targets for therapeutic intervention.
BACKGROUND: Normal cells produce energy (ATP) through mitochondrial oxidative phosphorylation in the presence of oxygen. However, many of the cancer cells produce energy with accelerated glycolysis and perform lactic acid production even under normoxic conditions called "The Warburg Effect". In this study, human lung carcinoma cells (A549) were incubated in either a normoxic or hypoxic environment containing 5 mM glucose (Glc 5), 25 mM glucose (Glc 25), or 10 mM galactose (OXPHOS/aglycemic), and then the bioenergetic pathway was anaylsed. METHODS AND RESULTS: HIF-1α stabilization of A549 cells with different metabolic conditions in normoxia and hypoxia (1% O2) was determined using the western blot method. After that, L-lactic acid analysis, p-PDH/PDH expression ratio, ATP analysis, and citrate synthase activity experiments were also performed. It was determined that HIF-1α stabilization reached the maximum level at the 4 h. It has been found that glycolytic cells produce approximately five times more lactate than OXPHOS cells under both normoxia and hypoxia conditions and also have a higher p-PDH/PDH ratio. It has been determined that citrate synthase activity in hypoxia of all metabolic conditions is lower than normoxia. It has been determined that Glc 5 and Glc 25 cells have more ATP production under normoxia than Glc 5 and Glc 25 cells in hypoxia. OXPHOS cells have showed more ATP production in hypoxia. CONCLUSION: It has been determined that oxidative phosphorylation became functional in a hypoxic aglycemic environment despite the metabolic programming regulated by HIF-1α. This data is important in determining targets for therapeutic intervention.
Authors: H Zhong; A M De Marzo; E Laughner; M Lim; D A Hilton; D Zagzag; P Buechler; W B Isaacs; G L Semenza; J W Simons Journal: Cancer Res Date: 1999-11-15 Impact factor: 12.701