Published online May 28, 2016. doi: 10.3748/wjg.v22.i20.4868
Peer-review started: October 12, 2015
First decision: March 7, 2016
Revised: March 20, 2016
Accepted: April 15, 2016
Article in press: April 15, 2016
Published online: May 28, 2016
AIM: To investigate the influence of phosphatidylinositol-3-kinase protein kinase B (PI3K/AKT)-HIF-1α signaling pathway on glycolysis in esophageal carcinoma cells under hypoxia.
METHODS: Esophageal carcinoma cell lines Eca109 and TE13 were cultured under hypoxia environment, and the protein, mRNA and activity levels of hypoxia inducible factor-1 alpha (HIF-1α), glucose transporter 1, hexokinase-II, phosphofructokinase 2 and lactate dehydrogenase-A were determined. Supernatant lactic acid concentrations were also detected. The PI3K/AKT signaling pathway was then inhibited with wortmannin, and the effects of hypoxia on the expression or activities of HIF-1α, associated glycolytic enzymes and lactic acid concentrations were observed. Esophageal carcinoma cells were then transfected with interference plasmid with HIF-1α-targeting siRNA to assess impact of the high expression of HIF-1α on glycolysis.
RESULTS: HIF-1α is highly expressed in the esophageal carcinoma cell lines tested, and with decreasing levels of oxygen, the expression of HIF-1α and the associated glycolytic enzymes and the extracellular lactic acid concentration were enhanced in the esophageal carcinoma cell lines Eca109 and TE13. In both normoxia and hypoxic conditions, the level of glycolytic enzymes and the secretion of lactic acid were both reduced by wortmannin. The expression and activities of glycolytic enzymes and the lactic acid concentration in cells were reduced by inhibiting HIF-1α, especially the decreasing level of glycolysis was significant under hypoxic conditions.
CONCLUSION: The PI3K/AKT pathway and HIF-1α are both involved in the process of glycolysis in esophageal cancer cells.
Core tip: Fluorescence analysis, spectrophotometry, real-time PCR, Western blot and siRNA interference technology were used to investigate the influence of phosphatidylinositol-3-kinase protein kinase B-HIF-1α signaling pathway on glycolysis under hypoxia in esophageal carcinoma cells. The results obtained provide experimental evidence for the mechanism of glycolysis enhanced by hypoxia.