Hyperthermia inhibits hypoxia-induced epithelial-mesenchymal transition in HepG2 hepatocellular carcinoma cells

AIM: To investigate the effect of hyperthermia on hypoxia-induced epithelial-rnesenchymal transition (EMT) in HepG2 hepatocellular carcinoma (HCC) cells, and its mechanism. METHODS: Cells were treated with hyperthermia at 43 degrees C for 0.5 h, followed by incubation under hypoxic or normoxic conditions for 72 h. Cell morphology was observed. Expressions of E-cadherin and vimentin were determined by immunofluorescence assay or Western blot. The protein and mRNA expressions of Snail were also determined by Western blot and reverse transcription-polymerase chain reaction. Cell migratory capacity was evaluated. RESULTS: Hypoxia induced EMT in HepG2 cells, which was evidenced by morphological, molecular and functional changes, including the formation of a spindle shape and the loss of cell contact. The expression of E-cadherin was decreased but the expression of vimentin was increased; also, the migratory capability was increased by 2.2 +/- 0.20-fold as compared with normoxia. However, those effects were inhibited by hyperthermia pretreatment. Furthermore, protein synthesis and mRNA expression of Snail in the cells were enhanced by hypoxia as compared with normoxia, and also significantly inhibited by hyperthermia pretreatment. CONCLUSION: Hyperthermia may inhibit hypoxia-induced EMT in HepG2 HCC cells, and the mechanism may involve inhibition of induced expression of Snail. (C) 2012 Baishideng. All rights reserved.