Effect of HIF-1αby RNAi on radiosensitivity in esophageal squamous carcinoma cell line Eca109 under hypoxia

OBJECTIVE:To investigate the expression of HIF-1αand EGFR in esophageal squamous carcinoma cell line Eca109 under hypoxia,in order to explore the effect of HIF-1αon radiosensitivity and its possible molecular mechanism.METHODS:CoCl_2 was used to mimic hypoxic tumor microcnvironment.mRNA levels of HIF- 1αand EGFR under hypoxia were detected by reverse transcription-polymerase chain reaction(RT-PCR),and protein levels were measured by immunohistochemistry.The effect silenced of HIF-1αgene on EGFR expression was assayed by Western blot.Radiosensitivity was evaluated via detection of apoptosis after radiation by flow cytometer(FCM),and then the effect of silencing HIF-1αon radiosensitivity was measured.RESULTS:Under hypoxia,HIF-1αmRNA had no significant change(P0.05),while its protein increased obviously.EGFR mRNA was up-regulated(P0.05),and its protein also increased accordingly.The siRNA targeting HIF-1αgene down-regulated HIF-1αin Eeal09 cells efficiently under hypoxia,and EGFR protein levels were down-regulated as well(P0.05).The radiosensitivity in esophageal carcinoma cell line Eca109 was lower under hypoxia than that in normoxia.The siRNA targeting HIF-1αcould partially reverse radioresistance.CONCLUSION:Hypoxia could increase HIF-1αprotein expression in esophageal squamous carcinoma Eca109 cell.Resistance to radiation enhanced in Eca109 cells maybe correlated with HIF-1αup-regulating the expression of EGFR mRNA and protein levels.Radiosensitivity could be augmented if HIF-1αwas effectively suppressed.