Kram Helena, Prokop Georg, Haller Bernhard, Gempt Jens, Wu Yang, Schmidt-Graf Friederike, Schlegel Jürgen, Conrad Marcus, Liesche-Starnecker Friederike
Department of Neuropathology, Institute of Pathology, School of Medicine, Technical University of Munich, Munich, Germany.
Institute of AI and Informatics in Medicine, School of Medicine, Technical University of Munich, Munich, Germany.
Front Oncol. 2022 Apr 21;12:841418. doi: 10.3389/fonc.2022.841418. eCollection 2022.
Despite the availability of various therapy options and being a widely focused research area, the prognosis of glioblastoma (GBM) still remains very poor due to therapy resistance, genetic heterogeneity and a diffuse infiltration pattern. The recently described non-apoptotic form of cell death ferroptosis may, however, offer novel opportunities for targeted therapies. Hence, the aim of this study was to investigate the potential role of ferroptosis in GBM, including the impact of treatment on the expression of the two ferroptosis-associated players glutathione-peroxidase 4 (GPX4) and acyl-CoA-synthetase long-chain family number 4 (ACSL4). Furthermore, the change in expression of the recently identified ferroptosis suppressor protein 1 (FSP1) and aldehyde dehydrogenase (ALDH) 1A3 was investigated.
Immunohistochemistry was performed on sample pairs of primary and relapse GBM of 24 patients who had received standard adjuvant treatment with radiochemotherapy. To identify cell types generally prone to undergo ferroptosis, co-stainings of ferroptosis susceptibility genes in combination with cell-type specific markers including glial fibrillary acidic protein (GFAP) for tumor cells and astrocytes, as well as the ionized calcium-binding adapter molecule 1 (Iba1) for microglial cells were performed, supplemented by double stains combining GPX4 and ACSL4.
While the expression of GPX4 decreased significantly during tumor relapse, ACSL4 showed a significant increase. These results were confirmed by analyses of data sets of the Cancer Genome Atlas. These profound changes indicate an increased susceptibility of relapsed tumors towards oxidative stress and associated ferroptosis, a cell death modality characterized by unrestrained lipid peroxidation. Moreover, ALDH1A3 and FSP1 expression also increased in the relapses with significant results for ALDH1A3, whereas for FSP1, statistical significance was not reached. Results obtained from double staining imply that ferroptosis occurs more likely in GBM tumor cells than in microglial cells.
Our study implies that ferroptosis takes place in GBM tumor cells. Moreover, we show that recurrent tumors have a higher vulnerability to ferroptosis. These results affirm that utilizing ferroptosis processes might be a possible novel therapy option, especially in the situation of recurrent GBM.
尽管存在多种治疗选择且是一个广泛关注的研究领域，但由于治疗抗性、基因异质性和弥漫性浸润模式，胶质母细胞瘤（GBM）的预后仍然很差。然而，最近描述的非凋亡形式的细胞死亡——铁死亡，可能为靶向治疗提供新的机会。因此，本研究的目的是探讨铁死亡在GBM中的潜在作用，包括治疗对两种与铁死亡相关的蛋白——谷胱甘肽过氧化物酶4（GPX4）和酰基辅酶A合成酶长链家族成员4（ACSL4）表达的影响。此外，还研究了最近鉴定出的铁死亡抑制蛋白1（FSP1）和醛脱氢酶（ALDH）1A3表达的变化。
对24例接受了标准放化疗辅助治疗的原发性和复发性GBM患者的样本对进行免疫组织化学检测。为了确定通常易于发生铁死亡的细胞类型，将铁死亡易感性基因与细胞类型特异性标志物进行共染色，包括用于肿瘤细胞和星形胶质细胞的胶质纤维酸性蛋白（GFAP），以及用于小胶质细胞的离子钙结合衔接分子1（Iba1），并辅以结合GPX4和ACSL4的双重染色。
虽然GPX4的表达在肿瘤复发期间显著降低，但ACSL4却显著增加。癌症基因组图谱数据集的分析证实了这些结果。这些深刻的变化表明复发肿瘤对氧化应激和相关铁死亡的易感性增加，铁死亡是一种以不受控制的脂质过氧化为特征的细胞死亡方式。此外，ALDH1A3和FSP1的表达在复发时也增加，ALDH1A3的结果具有统计学意义，而FSP1未达到统计学意义。双重染色结果表明，铁死亡在GBM肿瘤细胞中比在小胶质细胞中更易发生。
我们的研究表明铁死亡发生在GBM肿瘤细胞中。此外，我们表明复发性肿瘤对铁死亡更敏感。这些结果证实，利用铁死亡过程可能是一种新的治疗选择，尤其是在复发性GBM 的情况下。
