Functional cell surface expression of Toll-like receptor 9 promotes cell proliferation and survival in human hepatocellular carcinomas
Functional cell surface expression of Toll-like receptor 9 promotes cell proliferation and survival in human hepatocellular carcinomas
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DOI：
10.3892/ijo_00000730
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发表时间：
2010-10-01
影响因子：
5.2
通讯作者：
Takei, Yoshiyuki
中科院分区：
文献类型：
--
作者：
Tanaka, Junichiro;Sugimoto, Kazushi;Takei, Yoshiyuki
Toll 样受体 9 (TLR9) 是一种模式识别受体，参与免疫信号传导，通过识别包括未甲基化 CpG-DNA 在内的各种细菌和病毒成分，在细胞生存中发挥着至关重要的作用。 TLR9 在癌细胞中的表达和功能尚不清楚。我们研究了用 CpG 寡脱氧核苷酸 (ODN) 刺激后肝细胞癌细胞 (HCC) 中 TLR9 的表达以及 TLR9 信号传导的功能。在 85.7% 的 HCC 组织中观察到 TLR9 免疫组织化学染色阳性。 Western blot分析显示TLR9在HCC细胞系的细胞膜和细胞质中均表达。全长TLR9主要在膜上表达，而不是在细胞质中，而多切割形式的TLR9主要在细胞质中表达，而不是在膜上表达。在 HCC 细胞系中，TLR9 的细胞表面刺激促进细胞增殖，此外，TLR9 激动剂 CpG-ODN 通过上调细胞凋亡抑制剂（如 survivin、Bcl-xL、XIAP 和 cFLIP）降低抗癌药物阿霉素 (ADM) 的细胞毒性。尽管TLR9的细胞表面刺激不会激活NF-kappa B信号通路或I型IFN分泌通路，但基因芯片微阵列分析表明TLR9激动剂密切调节参与肿瘤发生和癌症进展的多个肿瘤相关基因和转录因子。总之，我们的结果表明，人 HCC 中 TLR9 的功能性细胞表面表达可能在肿瘤发生和癌症进展中发挥重要作用。
Toll-like receptor 9 (TLR9) is a pattern-recognition receptor that is involved in immune signaling and plays a crucial role in cell survival through recognition of various bacterial and viral components including unmethylated CpG-DNA. TLR9 expression and function in cancer cells are not well understood. We investigated the expression of TLR9, and the function of TLR9 signaling, in hepatocellular carcinoma (HCC) cells following stimulation with CpG-oligo-deoxynucleotides (ODNs). Positive immunohistochemical staining for TLR9 was observed in 85.7% of HCC tissues. Western blot analysis revealed that TLR9 was expressed both on the cell membrane and in the cytoplasm of HCC cell lines. Full-length TLR9 was predominantly expressed on the membrane rather than in the cytoplasm, whereas multiple cleaved forms of TLR9 were predominantly expressed in the cytoplasm rather than on the membrane. Cell surface stimulation of TLR9 promoted cell proliferation, and, furthermore, the TLR9 agonists, CpG-ODNs, reduced the cytotoxicity of the anti-cancer drug adriamycin (ADM) via up-regulation of apoptosis inhibitors such as survivin, Bcl-xL, XIAP and cFLIP, in HCC cell lines. Although cell surface stimulation of TLR9 did not activate either the NF-kappa B signaling pathway or the type-I IFN secretion pathway, gene chip microarray analysis indicated that TLR9 agonists closely regulated multiple oncology-related genes and transcription factors involved in tumorigenesis and cancer progression. In conclusion, our results indicate that functional cell surface expression of TLR9 in human HCC may play an important role in tumorigenesis and cancer progression.