Mechanism of notch signaling pathway involved in invasion and migration of hepatocellular carcinoma by regulating Snail/E-cadherin

Objective To investigate the mechanism of Notch signaling pathway in invasion and migration of hepatocellular carcinoma (HCC) cells. Methods The mRNA and protein expression levels of Snail and E-cadherin in hepatoma cells (HepG2) and non-tumor liver cell line (HL-7702) were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting respectively. Western blotting was used to detect the expression of NICD protein. The expression of Snail and E-cadherin mRNA and protein was detected by RT-PCR and Western blotting respectively after HepG2 cells were treated with 200 pmol small interfering RNA (siRNA)-Snail siRNA-Snail and 5 μmol/L DAPT. The invasive ability of HepG2 cells was examined by Transwell chamber. Results The expression levels of Snail mRNA and protein in HepG2 cells were significantly higher than those in HL-7702 cells (0.11±0.06 vs. 0.08±0.02, P=0.021; 0.46±0.06 vs. 0.21±0.04, P=0.032). The expression levels of E-cadherin mRNA and protein in HepG2 cells were significantly lower than those in HL-7702 cells (0.47±0.11 vs. 0.83±0.05, P=0.012; 0.17±0.03 vs. 0.25±0.06, P=0.004). As compared with the negative control group, the expression levels of Snail mRNA (0.76±0.13 vs. 0.25±0.06, P=0.031) and protein (0.81±0.24 vs. 0.27±0.08, P=0.024) in siRNA-Snail-treated group (Ss) decreased significantly, and the expression levels of E-cadherin mRNA (0.33±0.06 vs. 0.85±0.18, P=0.015) and protein (0.14±0.02 vs. 0.52±0.07, P=0.031) increased significantly, and the invasive ability (93.42±12.33 vs. 39.66±8.33, P=0.011) and migration (375.66±65.21 vs. 98.52±12.76, P=0.008) decreased significantly. The expression levels of NICD protein in HepG2 cells were significantly higher than those in HL-7702 cells (0.26±0.04 vs. 0.11±0.02, P=0.004). As compared with NT group, the expression of NICD protein was significantly inhibited by Notch pathway selective inhibitor DAPT (0.22±0.05 vs. 0.12±0.02, P=0.020), indicating that DAPT can effectively inhibit the activation of notch signaling pathway. The expression levels of Snail mRNA (0.56±0.08 vs. 0.23±0.05, P=0.004) and protein (0.72±0.06 vs. 0.27±0.04, P=0.030) could be down-regulated, and the expression levels of E-cadherin mRNA (0.21±0.03 vs. 0.54±0.06, P=0.011) and protein (0.32±0.07 vs. 0.77±0.08, P=0.021) could be upregulated by DAPT. Furthermore, DAPT could inhibit cell invasion (87.33±9.33 vs. 32.21±6.63, P=0.008) and migration (384.23±43.33 vs. 78.31±9.33, P=0.012) in HepG2 cells. Conclusion Notch signaling pathway plays an important role in invasion and migration of HCC cells probably through the regulation of Snail/E-cadherin. Key words: Carcinoma, hepatocellular; Notch signaling pathway; Snail; Invasion; Migration