Investigation of glucose metabolism and apoptosis of cancer cells under hypoxia conditions

Many of the cancer cells produce energy with accelerated glycolysis and perform lactic acid production even under normoxic conditions called "Warburg effect". They benefit from reprogrammed metabolism so that the apoptosis mechanism is not triggered. In this thesis, human lung carcinoma cells (A549) were incubated in normoxic and hypoxic environment containing 5 mM glucose (Gli 5), 25 mM glucose (Gli 25) and 10 mM galactose (OXPHOS/aglicemic), and the bioenergetic pathway and apoptosis mechanism were investigated. It was determined that HIF-1a stabilization reached the maximum level at the 4th hour. It has been found that glycolytic cells produce approximately 20 times more lactate than OXPHOS cells under both normoxia and hypoxia conditions and 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 Gli 5 and Gli 25 cells have more ATP production under normoxia than Gli 5 and Gli 25 cells in hypoxia. OXPHOS cells showed more ATP production in hypoxia. In hypoxia condition, aglycemic OXPHOS cells increase in early apoptosis (15.5% ±7.1), caspase-3 (6.1% ± 0.9), caspase-9 (30.4% ± 0.9) activities and high cytochrome c expression level, while a decrease has been detected in mitochondrial membrane potential (51.9%±0.4). As a result of this study, it was determined that oxidative phosphorylation became functional in aglycemic environment and apoptosis was triggered despite the metabolic programming regulated by HIF-1a. These data are important in determining targets for therapeutic intervention.