Glioblastoma Relapses Show Increased Markers of Vulnerability to Ferroptosis

Helena Kram; Georg Prokop; Bernhard Haller; Jens Gempt; Yang Wu; Friederike Schmidt-Graf; Jürgen Schlegel; Marcus Conrad; Friederike Liesche-Starnecker

doi:10.3389/fonc.2022.841418

Glioblastoma Relapses Show Increased Markers of Vulnerability to Ferroptosis

Front Oncol. 2022 Apr 21:12:841418. doi: 10.3389/fonc.2022.841418. eCollection 2022.

Authors

Helena Kram¹, Georg Prokop¹, Bernhard Haller², Jens Gempt³, Yang Wu¹, Friederike Schmidt-Graf⁴, Jürgen Schlegel¹, Marcus Conrad^{5

6}, Friederike Liesche-Starnecker¹

Affiliations

¹ Department of Neuropathology, Institute of Pathology, School of Medicine, Technical University of Munich, Munich, Germany.
² Institute of AI and Informatics in Medicine, School of Medicine, Technical University of Munich, Munich, Germany.
³ Department of Neurosurgery, School of Medicine, Technical University of Munich, Munich, Germany.
⁴ Department of Neurology, School of Medicine, Technical University of Munich, Munich, Germany.
⁵ Institute of Metabolism and Cell Death, Helmholtz Zentrum München, Neuherberg, Germany.
⁶ Laboratory of Experimental Oncology, Pirogov Russian National Research Medical University, Moscow, Russia.

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Keywords: cell death; ferroptosis; glioblastoma; glioma; immunohistochemistry; protein expression; relapse; therapy resistance.