Wang et al. BMC Cancer 2010, 10:415 http://www.biomedcentral.com/1471-2407/10/415 CMV and TLR9 expression need further investigation. At present time, the relationship between inflammation and tumorigenesis is widely accepted. However, the cel- lular and molecular mechanism involved in this process is incompletely understood. Our study indicated that the TLR9 signaling pathway constitute an important cellular pathway mediating this interaction in glioma, however, other independent retrospective and prospective studies will be necessary before direct clinical application of the current findings. The exact pathophysiological role of TLR9 in glioma is not known but it may represent a useful prognostic biomarker in glioma patients. The expression of TLR9 in glioma tissues is a major factor, through them, glioma cells can recognize either micro- bial pathogens or cellular debris and promote the expression and secretion of chemokines and cytokines. We demonstrated the relationship between TLR9 expression and glioma progression. Better understanding of the function and regulation of the TLR signaling pathways in glioma may shed new lights on understand- ing the mechanisms of glioma formation and progres- sion, as well as provide new targets for more effective regimens to treat gliomas. Conclusions TLR9 recognizes the ODN with CpG motif. After bind- ing with the ligand, TLR9 signal pathway may induce the proinflammatory or progrowth microenvironment of tumor. Our data indicated that TLR9 is expressed in glioma cell lines and glioma tissues, and the expression of TLR9 in glioma cells is functional. CpG ODN can sig- nificantly enhance the invasion of GBM cells, we con- firmed that TLR9 signaling was responsible for the enhanced invasion of glioma cells induced by CpG ODN. Screening a large collection of human glioma samples in tissue array with immunohistochemistry, we found that TLR9 expression correlated to the malignancy of gliomas, and TLR9 expression is an independent prognostic factor to predict patient PFS in GBM. Our data indicated that TLR9 may relate to glioma progression and the prognosis of GBM patients. In addition, our findings warrant cau- tion in the directly injection of TLR9 agonist CpG ODN into glioma tissues for the glioma immunotherapy. Acknowledgements This work was supported by Chinese National Natural Science Foundation (30300100) and supported by NCET(NCET-08-0867, Program for New Century Excellent Talents in Chinese University). We thank Yuling Yang and Na Liu for tissue sample collection and clinical data retrieval. Author details 1Department of Neurosurgery, The First Affiliated Hospital of China Medical University, Shenyang, China. 2Department of Biological Chemistry, China Medical University, Shenyang, China. 3Central Lab, The First Affiliated Hospital of China Medical University, Shenyang, China. 4Department of Neurosurgery, Beijing Tiantan Neurosurgical Institute, Beijing, China. 5Department of Page 10 of 11 Radiology, The First Affiliated Hospital of China Medical University, Shenyang, China. Authors’ contributions WC: carried out the tissue array analysis, interpreted the data and drafted the manuscript; CS: Carried out the cell culture and immunoflurecence staing; YY: carried out the RT-PCR analysis; QY: supported in the tissue collection and statistical data analysis; JT: supported in the tissue collection; XK: participated in design and coordination of the study; WA: conceived and designed the study, participated in study coordination, data analysis, data interpretation and drafting of the manuscript. All authors read and approved the final manuscript Competing interests The authors declare that they have no competing interests. Received: 28 November 2009 Accepted: 10 August 2010 Published: 10 August 2010 References 1. Bondy ML, Scheurer ME, Malmer B, Barnholtz-Sloan JS, Davis FG, Il’yasova D, Kruchko C, McCarthy BJ, Rajaraman P, Schwartzbaum JA, et al: Brain tumor epidemiology: consensus from the Brain Tumor Epidemiology Consortium. 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