Immediate early response protein 2 regulates hepatocellular carcinoma cell adhesion and motility via integrin ß1-mediated signaling pathway.

Human immediate early response 2 (IER2) has been reported to function as a potential transcriptional factor or transcriptional co­activator and seems to play a pivotal role in tumor cell motility and metastasis, however, its role and underlying mechanisms in hepatocellular carcinoma (HCC) remain unknown. Herein, we demonstrated that overexpression of IER2 in HCC cells increased cell adhesion to fibronectin, migration and invasion, whereas knockdown of IER2 displayed the opposite effects. In agreement with this phenotype, IER2 expression was positively correlated with the metastatic potential and integrin ß1 (ITGB1) expression in HCC cell lines. Moreover, we demonstrated a critical role for IER2 in regulation of HCC cell­extracellular matrix (ECM) adhesion and motility by the transcriptionally promoted ITGB1. Furthermore, we showed that ITGB1­focal adhesion kinase (FAK)­Src­paxillin signal pathway activated by IER2 may contribute to the HCC cell­ECM adhesion and motility. These results demonstrated that IER2 promoted HCC cell adhesion and motility probably by directly increasing ITGB1 expression and subsequently activating the ITGB1­FAK­Src­paxillin signal pathway.