Effects of suppression hypoxia-inducible factor-1α expression by small interfering RNA on glycolysis in esophageal carcinoma / 中华消化杂志

ABSTRACT

Objective To investigate the effects of hypoxia-inducible factor (HIF)-1α on glycolysis of human esophageal squamous carcinoma cells and the possible mechanism.Methods TE13 and Eca109 cells were cultured under normal oxygen (20％O2) and hypoxia (1％O2) conditions.The hypoxia was duration 6 hours,12 hours,24 hours and 48 hours.HIF-1α gene was stable silented by RNA interference method and TE13/small interfering HIF cells and Eca109/siHIF cells were obtained.The cell culture condition and time was same as TE13 and Eca109 cells.The changes of HIF-1α expression were detected by Western-blot.The changes of lactic acid concentration in cell culture supernatant were determined by Spectrophotometry.The changes of glucose transporter-1 (GLUT-1) and lactic dehydrogenase A (LDHA) expression at mRNA level were examined by realtime polymerase chain reaction.The changes of GLUT-1 and LDHA expression at protein level were tested by Western blot.Using t or t' test to analyze the effects of hypoxia duration on HIF-1αexpression at protein level.One-way ANOVA was applied for the difference analysis between the groups.Results In TE13 and Eca109 cells,the HIF-1α expression significantly increased under hypoxia condition and reached the peak at 12 hour (t=6.11,8.31; both P＜0.05).The lactic acid secretion of TE13/siHIF cells and Eca109/siHIF cells was (1.24±0.33) and (1.28±0.37) mmol/L,which significantly decreased when compared with TE13 and Eca109 cells [(3.25±1.34) and (4.91±1.69) mmol/L,t=2.53,3.59,both P＜0.05].The lactic acid secretion of TE13 and Eca109 cells significantly increased after hypoxia [(6.48±1.73) and (8.02± 1.95) mmol/L,t=2.715,2.050,both P＜0.05].There was no significant lactic acid secretion in TE13/siHIF cells and Eca109/siHIF cells after hypoxia (P ＞ 0.05).The expressions of GLUT-1 and LDHA at mRNA level were significantly suppressed in TE13/siHIF cells and Eca109/siHIF cells (normal oxygen:t=6.98,3.92,7.25,3.67,all P＜0.05).The expression of GLUT-1 at protein level remarkably weaked (normal oxygen:t=4.57、16.56,hypoxia:t=6.19、6.09,all P＜0.05),while the expression of LDHA at protein level slightly decreased (P＞0.05).Conclusions The level of glycolysis can be lowered by suppression HIF-1α expression in human esophageal squamous carcinoma cells.The pathway may be involved in the suppression of GLUT-1 and LDHA expression.Except for HIF-1α,there may be other regulating factors in LDHA protein expression at same time.