This study aims to investigate the effect of substances secreted or metabolized by vascular endothelial cells on epithelial-mesenchymal transition (EMT) of hepatocellular carcinoma cells under indirect co-culture condition. Human hepatocellular carcinoma cell line QGY-7703 was cultured , and then was co-cultured with conditioned medium of human umbilical vein endothelial cells (HUVEC). The morphological changes of QGY-7703 cells were observed by inverted phase contrast microscopy. The migration ability of QGY-7703 cells was analyzed by scratch-wound assays. The effect of conditioned medium on the expression and distribution of EMT related proteins was detected by Western blot and immunofluorescence assays, respectively. The results showed that the QGY-7703 cells gradually changed from polygonal to spindle shape, the migration ability promoted significantly, and both the expression and distribution of EMT related marker changed in a time-dependent manner after co-culturing. The results confirm that vascular endothelial cells can induce EMT in hepatocellular carcinoma cells under indirect co-culture condition.

The article aims to explore the optimal concentration of arsenic trioxide (As O ) on HepG2 of liver cancer cells, and the effect of As O on the migration, invasion and apoptosis of HepG2 cells. In this study, the activity of HepG2 cells treated with 0, 1, 2, 4, 8, 16, 32 μmol/L As O was tested by CCK-8 method, the semi-inhibitory concentration (IC50) was calculated, and the morphological changes of HepG2 cells were observed after the action of As O at IC50 concentration for 12, 24, 48 h. The effect of As O on cell migration and invasion ability was verified by wound healing experiment and Transwell invasion experiment. Western blot and qRT-PCR were used to detect the effects of As O on the gene and protein expression levels related to cell migration, invasion and apoptosis. The results showed that, compared with the control group, the activity of HepG2 cells decreased with the increase of the concentration of As O treatment, showing a dose-dependent effect, and its IC50 was 7.3 μmol/L. After 24 hours' treatment with 8 μmol/L As O , HepG2 cells underwent significant apoptosis, and its migration and invasion abilities were significantly reduced. In addition, the protein expression levels of RhoA, Cdc42, Rac1 and matrix metalloproteinase-9 (MMP-9) were down-regulated, the protein and mRNA expression levels of anti-apoptotic gene Bcl-2 were significantly down-regulated, and the protein and mRNA expression levels of pro-apoptotic genes Bax and Caspase-3 were significantly up-regulated. The above results indicate that certain concentration of As O can inhibit the migration and invasion of hepatocellular carcinoma cells and promote the apoptosis of hepatocellular carcinoma cells.