Expression and prognostic role of ubiquitination factor E4B in primary hepatocellular carcinoma

Ubiquitination factor E4B (UBE4B) has been speculated to have contradictory functions upon tumorigenesis as an oncogene or tumor suppressor in different types of cancers. We investigated the expression and prognostic role of UBE4B in primary hepatocellular carcinoma (HCC) using cell lines and 149 archived HCC samples. Correlation between the functions of UBE4B in HCC was also explored. We used human HCC cell lines (HepG2, Hep3B, SK-Hep1, Huh7, SMMC-7721, BEL-7402) and a normal hepatocyte cell line (LO2) along with HCC samples from patients who had undergone resection for HCC previously at our hospital. A battery of methods (real-time quantitative polymerase chain reaction; Western blotting; immunohistochjemical analyses; cell proliferation and colony formation assays; cell migration and cell invasion assays) were employed to assess various aspects of UBE4B.We found that UBE4B expression was upregulated aberrantly at mRNA and protein levels in human primary HCC tissues. Amplified expression of UBE4B was highly correlated with poor outcome. Silencing of UBE4B expression by siRNA inhibited the proliferation, colony formation, migration and invasion of HCC cells in vitro, and resulted in significant apoptosis that was associated with downregulation of expression of Bcl-2 and upregulation of expression of total p53, p-p53, Bax and Cleaved-Caspase3 in HCC cells. Our findings suggested that UBE4B might have an oncogenic role in human primary HCC, and that it could be used as a prognostic marker (as well as a potential molecular target) for the treatment of HCC.