CpG oligodeoxynucleotide induces apoptosis and cell cycle arrest in A20 lymphoma cells via TLR9-mediated pathways.
Recent studies have suggested that the anti-cancer activity of CpG-oligodeoxynucleotides (CpG-ODNs) is owing to their immunomodulatory effects in tumor-bearing host. The purpose of this study is to investigate the directly cytotoxic activity of KSK-CpG, a novel CpG-ODN with an alternative CpG motif, against A20 and EL4 lymphoma cells in comparison with previously used murine CpG motif (1826-CpG). To evaluate the potential cytotoxic effects of KSK-CpG on lymphoma cells, cell viability assay, confocal microscopy, flow cytometry, DNA fragmentation, Western blotting, and reverse transcription-polymerase chain reaction (RT-PCR) analysis were used. We found that KSK-CpG induced direct cytotoxicity in A20 lymphoma cells, but not in EL4 lymphoma cells, at least in part via TLR9-mediated pathways. Apoptotic cell death was demonstrated to play an important role in CpG-ODNs-induced cytotoxicity. In addition, both mitochondrial membrane potential decrease and G1-phase arrest were involved in KSK-CpG-induced apoptosis in A20 cells. The activities of apoptotic molecules such as caspase-3, PARP, and Bax were increased, but the activation of p27 Kip1 and ERK were decreased in KSK-CpG-treated A20 cells. Furthermore, autocrine IFN-γ partially contributed to apoptotic cell death in KSK-CpG-treated A20 cells. Collectively, our findings suggest that KSK-CpG induces apoptotic cell death in A20 lymphoma cells at least in part by inducing G1-phase arrest and autocrine IFN-γ via increasing TLR9 expression, without the need for immune system of tumor-bearing host. This new understanding supports the development of TLR9-targeted therapy with CpG-ODN as a direct therapeutic agent for treating B lymphoma.
Key Laboratory for Regenerative Medicine of the Ministry of Education, Department of Developmental & Regenerative Biology, Ji Nan University School of Life Science and Technology, Guangzhou 510632, People's Republic of China. qixufeng@jnu.edu.cn
Xu-Feng
XF
Qi
Li
L
Zheng
Cheol-Su
CS
Kim
Kyu-Jae
KJ
Lee
Dong-Heui
DH
Kim
Dong-Qing
DQ
Cai
Jun-Wen
JW
Qin
Yan-Hong
YH
Yu
Zheng
Z
Wu
Soo-Ki
SK
Kim
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase / Q000187:drug effects / Q000235:genetics; D007371:Interferon-gamma / Q000235:genetics / Q000378:metabolism; D008223:Lymphoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000235:genetics; D051379:Mice; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
C408982:CPG-oligonucleotide; D009838:Oligodeoxyribonucleotides; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9; D051028:bcl-2-Associated X Protein; D050760:Cyclin-Dependent Kinase Inhibitor p27; D007371:Interferon-gamma; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3