Abstract: Objective To investigate the effects of neurotrophin receptor-mediated melanoma antigen-encoding gene homology (NRAGE) on proliferation of human dental pulp cells (hDPCs) and MDPC-23. Methods Cells were infected by recombinant lentivirus to stably knock down the expression of NRAGE, then in vitro tissue explant method was used to conduct the primary culture of the hDPCs and MDPC-23, and the biological effects of NRAGE on the hDPCs and MDPC-23 were detected. Cell Counting Kit-8 was used to analyze effects of NRAGE on hDPCs and MDPC-23 proliferation, then the cell cycle distributions and apoptosis of hDPCs and MDPC-23 were performed by flow cytometric analysis. Simultaneously, the cell cycle and apoptosis were also detected after cells treated with IKK inhibitor.Then, mRNA and protein levels of NRAGE and nuclear factor-κB (NF-κB) protein expression were detected. Immunofluorescence assay was used to detect expression and location of NRAGE and NF-κB. Results The mRNA and protein levels of NRAGE decreased significantly after infected by recombinant lentivirus. Knockdown of NRAGE inhibited the proliferation and apoptosis of hDPCs and MDPC-23. Knockdown of NRAGE showed significant G0G1 retention in hDPCs, while no significant difference in MDPC- 23. Meanwhile, knockdown of NRAGE activated the NF-κB signaling pathway. After treated with IKK inhibitor, the effect of NRAGE knockdown on apoptosis was reversed in both hDPCs and MDPC-23. Conclusion Knockdown of NRAGE can inhibit proliferation of hDPCs and MDPC-23. NRAGE is a potent regulator for cell cycle and apoptosis of hDPCs. Knockdown of NRAGE can inhibit apoptosis of hDPCs and MDPC-23 through the NF-κB signaling pathway.

Key words: NRAGE, human dental pulp cells, MDPC-23, cell cycle, apoptosis, NF-κB signaling