The Nogo-B receptor promotes human hepatocellular carcinoma cell growth via the Akt signal pathway.

Nogo-B receptor (NgBR) is a type I receptor with a single transmembrane domain and specifically binds to ligand Nogo-B. A previous study demonstrated that NgBR was highly expressed in human breast invasive ductal carcinoma and promoted epithelial-mesenchymal transition in breast tumor cells. Our recent work found that NgBR expression was associated with a poor prognosis in human patients with hepatocellular carcinoma (HCC). Here, we elucidate that the increased expression of NgBR contributes toward the increased cell growth of human HCC cells both in vitro and in vivo. Cell viability and clonogenic survival analysis results demonstrated that knockdown of NgBR inhibits the cell growth in human HCC cells, which correlates with a reduction in the phosphorylation of Akt levels. Furthermore, overexpression of NgBR by the cotransfected pIRES-NgBR plasmid together with NgBR siRNA in human HCC cells can rescue impaired phosphorylation of Akt levels in NgBR knockdown human HCC cells. In addition, cell viability analyses showed that NgBR overexpression can rescue the cell growth inhibition presented in human HCC NgBR knockdown cells. Taken together, our results suggest that NgBR potentially acts as an oncogene in HCC by increasing Akt activity. Thus, NgBR may represent a new potential diagnostic and therapeutic target for the treatment of HCC.