Increased Expression of Early B-cell Factor 3 in Human Hepatocellular Carcinoma and the Effect of EBF3 Overexpression on HepG2 Cell Cycling

Abstract

Background: Previous studies suggested that early B-cell factor 3 (EBF3) might be a tumor suppressor. Methods: To explore the biological function of EBF3 in hepatocellular carcinoma (HCC) tissues, we measured the expression of EBF3 at mRNA level in 20 cases of HCC using realtime polymerase chain reaction (PCR) and the expression of EBF3 at protein level in nuclear extracts in 5 cases of HCC using Western blot. Results: The results showed that EBF3 mRNA was expressed in all HCC tissues, and only in 10 whole paired distant noncancerous tissues. The ratio of EBF3 mRNA to b 2 M mRNA in HCC tissues was significantly higher than that in distant liver noncancerous tissues (0.55 ± 0.12 versus 0.22 ± 0.23, t=5.69, P<0.001). EBF3 protein in nuclear extracts of HCC tissues was about 4-fold that in distant noncancerous tissues (26.35 ± 14.06 versus 7.86 ± 8.47, t=2.52, P=0.036). We also successfully constructed a eukaryotic expression vector for human EBF3 fused with enhanced green fluorescent protein (EGFP) and expressed EBF3-EGFP fusion protein in HepG2 cells. It was found that expression of EBF3-EGFP fusion protein in HepG2 induced cell proliferation by increasing the number of cells in S phase. Conclusion: These findings suggested that the expression of EBF3 at both mRNA and protein levels was up-regulated in HCC tissues, and that EBF3 may play a critical pathological role in HCC.