Effect of extracellular HSP70/HSP70-PCs on epithelial-mesenchymal transition of human hepatocellular carcinoma HepG2 cells

AIM：To investigate the effect of extracellular heat-shock protein 70 (HSP70)/HSP70-peptide complexes (HSP70-PCs) on epithelial-mesenchymal transition (EMT) of human hepatocellular carcinoma HepG2 cells and its probable mechanism. METHODS：HepG2 cells were divided into 3 groups: control group, HSP70/HSP70-PCs (2 mg/L) group and LY294002+HSP70/HSP70-PCs group. The mRNA and protein expression of epithelial cell surface marker E-cadherin, mesenchymal cell surface marker α-smooth muscle actin (α-SMA), phosphatidylinositol 3-kinase (PI3K) and hypoxia-inducible factor 1α (HIF-1α) was examined by real-time RT-PCR and Western blotting. RESULTS：Extracellular HSP70/HSP70-PCs promoted the initiation of EMT of HepG2 cells. The expression of HIF-1α and PI3K significantly increased in the process of EMT of HepG2 cells. After PI3K was blocked by LY294002, EMT did not occur and HIF-1α was not up-regulated in HepG2 cells. CONCLUSION：Extracellular HSP70/HSP70-PCs may promote EMT of hepatocellular carcinoma cells via PI3K/HIF-1α signaling pathway.