Wang et al. BMC Cancer 2010, 10:415 http://www.biomedcentral.com/1471-2407/10/415 R E S E A R C H A R T I C L E Open Access TLR9 expression in glioma tissues correlated to glioma progression and the prognosis of GBM patients Chao Wang1,4, Shouqiang Cao1, Ying Yan2, Qiao Ying3, Tao Jiang4, Ke Xu5, Anhua Wu1* Abstract Background: Our study aims to evaluate the expression of TLR9 in glioma tissues, examine the association between TLR9 expression, clinicopathological variables, and glioma patient outcome, we further characterized the direct effects of TLR9 agonist CpG ODN upon the proliferation and invasion of glioma cells in vitro. Methods: RT-PCR and immunofluorescence were used to determine the expression of TLR9 in glioma cell lines and clinical glioma samples. Tissue microarry and immunohistochemistry were applied to evaluated TLR9 expression in 292 newly diagnosed glioma and 13 non-neoplastic brain tissues. We further investigated the effect of CpG ODN on the proliferation and invasion of glioma cells in vitro with MTT assays and matrigel transwell assay respectively. Results: RT-PCR showed that TLR9 expressed in all the glioma samples and glioma cell lines we examined. The tissue array analysis indicated that TLR9 expression is correlated with malignancy of glioma (p < 0.01). Multivariate Cox regression analysis revealed that TLR9 expression is an independent prognostic factor for PFS of GBM patients (P = 0.026). TLR9 agonist CpG ODN has no significant effect on glioma proliferation, but matrigel transwell analysis showed that TLR9 agonist CpG ODN can significantly enhance glioma invasion in vitro. Conclusions: Our data indicated that TLR9 expression increases according to the histopathological grade of glioma, and the TLR9 expression level is related to the PFS of GBM patients. In addition, our findings warrant caution in the directly injection of TLR9 agonist CpG ODN into glioma tissues for the glioma immunotherapy. Background Glioma is the most common brain tumor, although with the combined treatment strategy including surgery, radiotherapy and chemotherapy, prognosis for high grade glioma especially glioblastoma multiform (GBM) altered little over the past 10 years, with a median survi- val only about 1 year[1], thus new treatment strategy are urgently needed. Immunotherapy is a promising treat- ment strategy for gliomas since the activated lymphocyte can specifically target and destroy tumor cells[2]. Recently, CpG based immunotherapy are intensively investigated. CpG is synthetic ODN with unmethylated CG dinucleotides within particular sequence contexts [3], CpG ODN has been used in clinical trials as a * Correspondence: anhuawu@yahoo.com 1Department of Neurosurgery, The First Affiliated Hospital of China Medical University, Shenyang, China Full list of author information is available at the end of the article vaccine adjuvant for immunotherapy of cancer since it can mimic microbial DNA and activate immune system through the binding of TLR9. TLR9 belong to TLRs families which are evolutionarily well conserved trans- membrane proteins that recognize microbe derived molecular patterns [4]. TLR9 resides in the endoplasmic reticulum and its activation results in increased produc- tion of inflammatory mediators [5,6], Except plasmacy- toid DC and B cells, TLR9 can also expressed in breast [7], gastric [8], lung [9] and prostate [10] cancer cells. Accumulating data indicated that TLR9 agonist CpG ODN can promote tumor development and metastasis [7,10-12]. We proposed that TLR9 signal pathway may also be important in glioma growth and progression. However its precise role in glioma remains unclear with studies supporting both glioma promotion and glioma inhibition results, there is report that local CpG immu- notherapy can prolong the survival of mouse with © 2010 Wang et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.