Nemopilema nomurai jellyfish venom exerts an anti-metastatic effect by inhibiting Smad- and NF-κB-mediated epithelial–mesenchymal transition in HepG2 cells

Epithelial–mesenchymal transition (EMT) is a key initial step in metastasis for malignant cancer cells to obtain invasive and motile properties. Inhibiting EMT has become a new strategy for cancer therapy. In our previous in vivo study, Nemopilema nomurai jellyfish venom (NnV) -treated HepG2 xenograft mice group showed that E-cadherin expression was strongly detected compared with non-treated groups. Therefore, this study aimed to determine whether NnV could inhibit the invasive and migratory abilities of HepG2 human hepatocellular carcinoma cells and to examine its effect on EMT. Our results revealed that transforming growth factor (TGF)-β1 induced cell morphological changes and downregulated E-cadherin and β-catenin expression, but upregulated N-cadherin and vimentin expression through the Smad and NF-κB pathways in HepG2 cells. Treatment of TGF-β1-stimulated HepG2 cells with NnV reversed the EMT-related marker expression, thereby inhibiting cell migration and invasion. NnV also significantly suppressed the activation of p-Smad3, Smad4, and p-NF-κB in a dose-dependent manner. These data indicated that NnV can significantly suppress cell migration and invasion by inhibiting EMT in HepG2 cells, and therefore might be a promising target for hepatocellular carcinoma therapeutics.