Chahlavi Ali, Rayman Patricia, Richmond Amy L, Biswas Kaushik, Zhang Renliang, Vogelbaum Michael, Tannenbaum Charles, Barnett Gene, Finke James H
Department of Neurosurgery, Brain Tumor Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
Cancer Res. 2005 Jun 15;65(12):5428-38. doi: 10.1158/0008-5472.CAN-04-4395.
Here we report that glioblastoma multiforme (GBM) mediates immunosuppression by promoting T-cell death via tumor-associated CD70 and gangliosides that act through receptor-dependent and receptor-independent pathways, respectively. GBM lines cocultured with T cells induced lymphocyte death. The GBM lines were characterized for their expression of CD70, Fas ligand (FasL), and tumor necrosis factor-alpha (TNF-alpha), and the possible participation of those molecules in T-cell killing was assessed by doing GBM/T cell cocultures in the presence of anti-CD70 antibodies, Fas fusion proteins, or anti-TNF-alpha antibodies. CD70 but not TNF-alpha or FasL is responsible for initiating T-cell death via the receptor-dependent pathway. Of the four GBM cell lines that induced T-cell death, three highly expressed CD70. Two nonapoptogenic GBM lines (CCF3 and U138), on the other hand, had only minimally detectable CD70 expression. Blocking experiments with the anti-CD70 antibody confirmed that elevated CD70 levels were involved in the apoptogenicity of the three GBM lines expressing that molecule. Gangliosides were found to participate in the induction of T-cell apoptosis, because the glucosylceramide synthase inhibitor (PPPP) significantly reduced the abilities of all four apoptogenic lines to kill the lymphocytes. High-performance liquid chromatography (HPLC) and mass spectroscopy revealed that GM2, GM2-like gangliosides, and GD1a were synthesized in abundance by all four apoptogenic GBM lines but not by the two GBMs lacking activity. Furthermore, gangliosides isolated from GBM lines as well as HPLC fractions containing GM2 and GD1a were directly apoptogenic for T cells. Our results indicate that CD70 and gangliosides are both products synthesized by GBMs that may be key mediators of T-cell apoptosis and likely contribute to the T-cell dysfunction observed within the tumor microenvironment.
在此我们报告，多形性胶质母细胞瘤（GBM）通过肿瘤相关的CD70和神经节苷脂分别经由受体依赖性和受体非依赖性途径促进T细胞死亡，从而介导免疫抑制。与T细胞共培养的GBM细胞系诱导淋巴细胞死亡。对GBM细胞系进行CD70、Fas配体（FasL）和肿瘤坏死因子-α（TNF-α）表达特征分析，并通过在抗CD70抗体、Fas融合蛋白或抗TNF-α抗体存在的情况下进行GBM/T细胞共培养，评估这些分子在T细胞杀伤中的可能作用。CD70而非TNF-α或FasL通过受体依赖性途径引发T细胞死亡。在诱导T细胞死亡的四种GBM细胞系中，有三种高表达CD70。另一方面，两种无凋亡活性的GBM细胞系（CCF3和U138）仅能检测到极低水平的CD70表达。用抗CD70抗体进行的阻断实验证实，CD70水平升高与表达该分子的三种GBM细胞系的凋亡活性有关。发现神经节苷脂参与T细胞凋亡的诱导，因为葡萄糖神经酰胺合酶抑制剂（PPPP）显著降低了所有四种具有凋亡活性的细胞系杀伤淋巴细胞的能力。高效液相色谱（HPLC）和质谱分析显示，所有四种具有凋亡活性的GBM细胞系均大量合成GM2、GM2样神经节苷脂和GD1a，而两种无活性的GBM细胞系则不合成。此外，从GBM细胞系分离的神经节苷脂以及含有GM2和GD1a的HPLC馏分对T细胞具有直接凋亡作用。我们的结果表明，CD70和神经节苷脂均为GBM合成的产物，它们可能是T细胞凋亡的关键介质，并可能导致肿瘤微环境中观察到的T细胞功能障碍。
