HBx and HBs regulate RhoC expression by upregulating transcription factor Ets-1.

The available evidence suggests that HBV proteins play an important role in the development of hepatocellular carcinoma (HCC). RhoC, a member of the Rho subfamily of the Ras superfamily of homologous genes, had been implicated in tumorigenesis and tumor progression. In a previous study, we demonstrated that HBx and HBs could up-regulate RhoC expression by enhancing its promoter activity. However, the specific mechanisms remain unclear. Here, we demonstrate that overexpression of Ets-1 results in upregulation of RhoC promoter activity and mRNA and protein levels. Expression of transcription factor Ets-1 was significantly higher in HepG2.2.15 cells than that in HepG2 cells. Meanwhile, infection of HepG2 cells with an HBV-adenovirus recombinant virus led to up-regulation of Ets-1. Of the four HBV proteins, HBx and HBs, could increase expression of Ets-1, which consequently contributed to the upregulation of RhoC. These findings might provide a novel insight into HBV-induced HCC metastasis.