Inhibitory Effect Of CpG ODN To Proliferation Of Human Lung Adenocarcinoma Cell A549

Lung cancer is the leading cause of cancer mortality, consisting of non-small cell lung cancer ( NSCLC ) and small cell lung caner ( SCLC ), NSCLC is about 80% of prevalence cases, but about 20% in SCLC. Although treatment with surgery, radiation ,chemotherapy or combination of them, the long-term survival for lung cancer patients remains low. Most of lung cancer patients lost the surgical opportunity or the tumor can not be cut off completely because of late stage. Lung cancer have various surface bio-markers, lacking of tumor specific antigen, this lead to difficulty of tumor therapy. biological therapy, molecular targeted therapy and gene therapy have been developed, the efficacy of therapy, however, is still not satisfied. As a result, new therapies are needed for lung cancer treatment.CpG ODN is oligodeoxynucleotid containing unmethylated cytosine-phosphorate-guanine (CpG) dinucleotides motifs, following internalization into cell, CpG motifs seem to be bound and recognized by TLR9, leading to the rapid recruitment and/or activation of the adaptor molecules, such as myeloid differentiation factor88 (MyD88), interleukin-1 receptor-associated kinase-1 (IRAK1), interferon regulatory factor-7 (IRF7), and tumour-necrosis factor-αreceptor activated factor-6 (TRAF6). This results in the rapid activation of several mitogen-activated protein kinases (MAPK), including extracellular receptor kinase (ERK), p38, and Jun N-terminal kinase, as well as the IκB complex, and these pathways converge on the nucleus to alter gene transcription.CpG ODN can activate B cell and plasmacytoid dendritic cell (pDC) both expressing TLR9, and stimulate NK cell, T cell, macrophage and indirectly, inducing innate immunity and a Th1 biased cellular and humoral effector functions of adaptive immunity. Therefore, CpG ODN is a potential adjuvant, furthermore ,it is also applied in therapy of tumor, infectious disease and asthma/allergy. However, no direct effect of CpG on tumor cells in vitro was reported, consequently, we investigate the direct effect of CpG ODN on human lung adenocarcinoma cell A549 in vitro.The direct effect of CpG ODN to human lung adenocarcinoma cell A549 in vitro was detected by cell counting assay, MTT assay and 3H-TdR incorporation assay, A549 cell apoptosis induced by CpG ODN was detected via flow cytometry ( FCM ).CpG ODN can inhibit proliferation of A549 cell according to results of cell counting assay, MTT assay and 3H-TdR incorporation assay; as all know, Although sensitivity of cell counting assay was lower, it is macroscopic and substantial, it is verified by observation under microscope that CpG ODN can inhibit A549 cell proliferation. In addition, the similar results was obtained by MTT assay on day 5 after administration of CpG ODN. Furthermore, the inhibitory effect of CpG ODN on A549 cell proliferation depended on dosage and time. From apoptosis assay through FCM, it is found that there are about 1% of A549 cells are apoptotic in absence of CpG ODN, and apoptotic cell increased to about 10% on day 5 after applied with CpG 2006, proving that CpG ODN may induced apoptosis of A549 cell in vitro. Moreover, it is also found that CpG ODN was no toxicity to A549 cell, and the impurity in CpG ODN have no influence on inhibitory effect of CpG ODN to A549 cell proliferation. Together, B-type CpG ODN can induce proliferation-inhibition and apoptosis of A549 cell, and More researches, such as signal transduction or CpG ODN localization , was needed to investigate the apoptotic mechanisms.