CpG-oligodeoxynucleotides suppress the proliferation of A549 lung adenocarcinoma cells via toll-like receptor 9 signaling and upregulation of Runt-related transcription factor 3 expression

The aim of the present study was to investigate the effect of CpG-oligodeoxynucelotides (CpG-ODN) on the proliferation of the A549 human lung adenocarcinoma cell line and the expression of Runt-related transcription factor 3 (Runx3) and investigate the association between the toll-like receptor 9 (TLR9) signaling pathway and Runx3 expression during A549 cell proliferation. Different concentrations of CpG-ODN were used in this study to stimulate A549 cells and the expression of Runx3 at the mRNA or protein level was detected by reverse transcription-polymerase chain reaction or western blot analysis. Moreover, Runx3 siRNA was synthesized and transiently transfected into the A549 cells and the MTT assay was used to detect the effects of CpG-ODN on transfected cell growth. Our data demonstrated that CpG-ODN significantly inhibited the proliferation of A549 cells. The expression of Runx3 in the mRNA and protein level was increased in A549 cells stimulated by CpG-ODN. The CpG-ODN-stimulated cell proliferation was significantly inhibited in Runx3 siRNA-transfected A549 cells. In conclusion, CpG-ODN may bind to TLR9, inhibit the proliferation of A549 cells and upregulate the expression of Runx3.