Abstract
Preclinical and early clinical trials indicate that synthetic oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG ODN) have potent immunostimulatory effects and can enhance the anticancer activity of a variety of cancer treatments. In this study, CpG ODN1826 was used to increase the radiosensitivity of human pulmonary adenocarcinoma cell line A549, and some underlying mechanisms were also detected. With the treatment of CpG ODN on A549 cells, there was an upregulation of CD40, CD80, CD86, and MHC-II on A549 cells in association with Th1 cytokine production. Further, the protein level of toll-like receptor (TLR)-4 was decreased, whereas TLR-9 was enhanced. Flow cytometry results showed that CpG ODN could increase mitochondrial membrane potential and subsequently promote the apoptosis of A549 cells, resulting in increased radiosensitivity. These results suggest a regulatory role of CpG ODN1826 in enhancing the radiosensitivity of A549 cells by activating the adaptive and innate immune responses, thereby providing a new potential strategy to the treatment of malignant tumors.