Abstract: Objective To explore expression and function of EMS1/cortactin in HCC cell line HepG2. Methods RT-qQPCR was used to detect expression of EMS1. Location of cortactin (protein encoded by EMS1 gene) was detected with immunofluorescence assay. L02 (normal liver cell) was used as control. Then a short-hairpin-RNA -expression plasmid against EMS1 (pS-EMS1) was constructed and transfected into HepG2. The downregulation of EMS1 and cortactin were tested by RT-qPCR and Western blot analysis. The proliferation, division capacity, migration and invasion of HepG2 were tested through CCK8 assay, flow cytometry assay, wound healing and transwell invasion assays, respectively. Results As compared with L02， the level of EMS1 gene in HepG2 was 10.5 (relative fold units). Confocal microscopy showed that cortactin in HepG2 accumulated to a high extent in the cell-substratum contact sites while it diffusely distributed in the cytoplasm in LO2. As compared with untreated group, RNAi-mediated suppression of EMS1/ cortactin in HepG2 cells was 68.00% in mRNA level, and 52.80% in protein level. In CCK8 assay, the inhibiting rate was 9.50% while in flow cytometry assay，reduction in the S phase was 37.89%.Inhibiting rates of migration and invasion were 45.40% and 64.91% (P<0.05, respectively). Conclusions EMS1/ cortactin plays a more important role in cellular invasive potential of HCC cell line HepG2.

Key words: EMS1/cortactin, location,migration, invasion, RNAi