Flüh Charlotte, Chitadze Guranda, Adamski Vivian, Hattermann Kirsten, Synowitz Michael, Kabelitz Dieter, Held-Feindt Janka
Department of Neurosurgery, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Straße 3, Haus 41, 24105, Kiel, Germany.
Institute of Immunology, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Straße 3, Haus 17, 24105, Kiel, Germany.
Histochem Cell Biol. 2018 Mar;149(3):219-233. doi: 10.1007/s00418-018-1633-5. Epub 2018 Jan 22.
Glioblastoma multiforme (GBM) is a highly malignant brain tumor. Tumor stem cells have a major influence on tumor malignancy, and immunological escape mechanisms, involving the Natural Killer Group 2, member D (NKG2D) receptor-ligand-system, are key elements in tumor immuno-surveillance. We analyzed the expression profile and localization of NKG2D ligands (NKG2DL) and embryonic and neural stem cell markers in solid human GBM and stem-like cells isolated from glioma cell lines by qRT-PCR and immunohistochemistry, including quantitative analysis. We also evaluated the effect of Temozolomide (TMZ), the standard chemotherapeutic agent used in GBM therapy, on NKG2DL expression. NKG2DL-positive cells were mostly found scattered and isolated, were detectable in glial fibrillary acidic protein (GFAP)-positive tumor regions and partly in the penumbra of tumor vessels. NKG2DL were found in a distinct tumor stem-like cell subpopulation and were broadly costained with each other. Quantitative analysis revealed, that dependent on the individual NKG2DL investigated, cell portions costained with different stem cell markers varied between small (Musashi-1) and high (KLf-4) amounts. However, a costaining of NKG2DL with CD3γ, typically found in T cells, was also observable, whereas CD11b as a marker for tumor micoglia cells was only rarely costained with NKG2DL. Stem-like cells derived from the glioma cell lines T98G and U251MG showed a distinct expression pattern of NKG2DL and stem cell markers, which seemed to be balanced in a cell line-specific way. With differentiation, T98G displayed less NKG2DL, whereas in U251MG, only expression of most stem cell markers decreased. In addition, stimulation with TMZ led to a significant upregulation of NKG2DL in stem-like cells of both lines. As stem-like glioma cells tend to show a higher expression of NKG2DL than more differentiated tumor cells and TMZ treatment supports upregulation of NKG2DL, the NKG2D system might play an important role in tumor stem cell survival and in GBM therapy.
多形性胶质母细胞瘤（GBM）是一种高度恶性的脑肿瘤。肿瘤干细胞对肿瘤恶性程度有重大影响，而涉及自然杀伤细胞2族D成员（NKG2D）受体-配体系统的免疫逃逸机制是肿瘤免疫监视的关键要素。我们通过qRT-PCR和免疫组织化学（包括定量分析）分析了人实体GBM和从胶质瘤细胞系分离的干细胞样细胞中NKG2D配体（NKG2DL）以及胚胎和神经干细胞标志物的表达谱和定位。我们还评估了GBM治疗中使用的标准化疗药物替莫唑胺（TMZ）对NKG2DL表达的影响。NKG2DL阳性细胞大多呈散在和孤立分布，在胶质纤维酸性蛋白（GFAP）阳性肿瘤区域以及部分肿瘤血管的半暗带中可检测到。NKG2DL存在于一个独特的肿瘤干细胞样细胞亚群中，并且彼此广泛共染。定量分析显示，根据所研究的个体NKG2DL，与不同干细胞标志物共染的细胞比例在少量（Musashi-1）和大量（KLf-4）之间变化。然而，也观察到NKG2DL与通常在T细胞中发现的CD3γ共染，而作为肿瘤小胶质细胞标志物的CD11b很少与NKG2DL共染。源自胶质瘤细胞系T98G和U251MG的干细胞样细胞显示出NKG2DL和干细胞标志物的独特表达模式，这似乎以细胞系特异性方式保持平衡。随着分化，T98G显示出较少的NKG2DL，而在U251MG中，只有大多数干细胞标志物的表达下降。此外，用TMZ刺激导致这两种细胞系的干细胞样细胞中NKG2DL显著上调。由于干细胞样胶质瘤细胞往往比分化程度更高的肿瘤细胞显示出更高的NKG2DL表达，并且TMZ治疗支持NKG2DL上调，NKG2D系统可能在肿瘤干细胞存活和GBM治疗中发挥重要作用。
