Tumorbiological Laboratory, Department of Neurosurgery, Ludwig-Maximilians-University, Klinikum Grosshadern, Marchioninistr. 15, 81377, Munich, Germany.
Department of Radiation Oncology, Klinikum Rechts der Isar, Technical University (TU) Munich, Ismaninger Str. 22, 81675, Munich, Germany.
J Neurooncol. 2017 Dec;135(3):443-452. doi: 10.1007/s11060-017-2600-z. Epub 2017 Aug 28.
A unique feature in several non-CNS-tumors is the overexpression of heat shock protein 70 (Hsp70, HSPA1A) in the cytosol, but also its unusual plasma membrane expression and release. Although in gliomas, cytosolic Hsp70 levels are not associated with histological grading, the role of membrane bound and released Hsp70 is still completely unknown. Membrane bound as well as cytosolic Hsp70 can be detected in viable tumor cells with the monoclonal antibody (mAb) cmHsp70.1. Herein, we analysed membrane bound Hsp70 levels in primary and secondary gliomas of different grades and on isolated glioma subpopulations (endothelial cells, CD133-positive cells, primary cultures) by immunohistochemistry and flow cytometry using cmHsp70.1 mAb. Extracellular Hsp70 was determined by a commercial Hsp70 sandwich ELISA (R&D) in plasma samples of glioblastoma patients and healthy volunteers. We found an overexpression of Hsp70 in primary glioblastomas compared to low-grade, anaplastic, or secondary gliomas as determined by immunohistochemistry. Especially in flow cytometry, a strong plasma membrane Hsp70 expression was only observed in primary but not secondary glioblastomas. Within the heterogeneous tumor mass, CD133-positive tumor-initiating and primary glioblastoma cells showed a high membrane Hsp70 expression density, whereas endothelial cells, isolated from glioblastoma tissues only showed a weak staining pattern. Also in plasma samples, secreted Hsp70 protein was significantly increased in patients harbouring primary glioblastomas compared to those with secondary and low grade glioblastomas. Taken together, we show for the first time that cytosolic, membrane bound and extracellular Hsp70 is uniquely overexpressed in primary glioblastomas.
在几种非中枢神经系统肿瘤中，一个独特的特征是热休克蛋白 70（Hsp70，HSPA1A）在细胞质中的过度表达，但也存在其异常的质膜表达和释放。尽管在神经胶质瘤中，细胞质 Hsp70 水平与组织学分级无关，但膜结合和释放的 Hsp70 的作用仍然完全未知。膜结合和细胞质 Hsp70 都可以用单克隆抗体（mAb）cmHsp70.1 在存活的肿瘤细胞中检测到。在此，我们通过免疫组织化学和使用 cmHsp70.1 mAb 的流式细胞术分析了不同分级的原发性和继发性神经胶质瘤以及分离的神经胶质瘤亚群（内皮细胞、CD133 阳性细胞、原代培养物）中的膜结合 Hsp70 水平。在胶质母细胞瘤患者和健康志愿者的血浆样本中，通过商业 Hsp70 夹心 ELISA（R&D）测定细胞外 Hsp70。我们发现，与低级别、间变性或继发性神经胶质瘤相比，原发性神经胶质母细胞瘤中 Hsp70 的表达过度。特别是在流式细胞术中，仅在原发性神经胶质母细胞瘤中观察到强烈的质膜 Hsp70 表达，而在继发性神经胶质母细胞瘤中则没有。在异质肿瘤块中，CD133 阳性的肿瘤起始细胞和原发性神经母细胞瘤细胞表现出高的膜 Hsp70 表达密度，而内皮细胞从神经母细胞瘤组织中仅显示出弱的染色模式。在血浆样本中，与患有继发性和低级别神经胶质瘤的患者相比，原发性神经胶质母细胞瘤患者的分泌性 Hsp70 蛋白显著增加。总之，我们首次表明，细胞质、膜结合和细胞外 Hsp70 在原发性神经胶质母细胞瘤中过度表达。
