RPB5-mediating protein is required for the proliferation of hepatocellular carcinoma cells

Abstract

RPB5-mediating protein (RMP) is associated with the RNA polymerase II subunit RPB5. RMP functionally counteracts the transcriptional activation of hepatitis B virus X protein that has been shown to play a role in the development of hepatocellular carcinoma (HCC). However, the effect of RMP on the growth of HCCremains unclear. In this study, we characterized the potential role of RMP in the proliferation of human HCC cells using two cell lines, SMMC-7721 and HepG2. We found that RMP expression increased when HCC cells were treated with 60Co γ-irradiation. Cell growth and colony formation assays suggest that RMP plays an antiapoptotic role in the proliferation and growth of HCC cells.Wealso show that RMP depletion induced the G2 arrest of HCC cells characterized by the decreased expression of Cdk1 and Cyclin B. Tumor formation assays further confirmed the in vivo requirement of RMP during HCC growth. In conclusion, our results demonstrate that RMP is a radiation-sensitive factor, and it may play essential roles inHCC growth by affecting the proliferation and apoptosis of HCC cells. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.