Overexpression of Cystine/Glutamate Antiporter xCT Correlates with Nutrient Flexibility and ZEB1 Expression in Highly Clonogenic Glioblastoma Stem-like Cells (GSCs)

Katharina Koch; Rudolf Hartmann; Abigail Kora Suwala; Dayana Herrera Rios; Marcel Alexander Kamp; Michael Sabel; Hans-Jakob Steiger; Dieter Willbold; Amit Sharma; Ulf Dietrich Kahlert; Jarek Maciaczyk

doi:10.3390/cancers13236001

Overexpression of Cystine/Glutamate Antiporter xCT Correlates with Nutrient Flexibility and ZEB1 Expression in Highly Clonogenic Glioblastoma Stem-like Cells (GSCs)

Cancers (Basel). 2021 Nov 29;13(23):6001. doi: 10.3390/cancers13236001.

Authors

Katharina Koch^{1

2}, Rudolf Hartmann³, Abigail Kora Suwala^{4

5

6}, Dayana Herrera Rios^{1

7}, Marcel Alexander Kamp⁸, Michael Sabel¹, Hans-Jakob Steiger¹, Dieter Willbold^{3

9}, Amit Sharma¹⁰, Ulf Dietrich Kahlert^{1

11}, Jarek Maciaczyk^{10

12}

Affiliations

¹ Department of Neurosurgery, University Hospital Duesseldorf, 40225 Duesseldorf, Germany.
² IUF-Leibniz Research Institute for Environmental Medicine, 40225 Duesseldorf, Germany.
³ Institute of Biological Information Processing (IBI-7) Structural Biochemistry, Forschungszentrum Juelich, 52425 Juelich, Germany.
⁴ Department of Neurological Surgery, Helen Diller Research Center, University of California San Francisco, San Francisco, CA 94158, USA.
⁵ Department of Neuropathology, Institute of Pathology, Heidelberg University Hospital, 69120 Heidelberg, Germany.
⁶ Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), German Consortium for Translational Cancer Research (DKTK), 69120 Heidelberg, Germany.
⁷ Skin Cancer Unit of the Dermatology Department, West German Cancer Center, University Duisburg-Essen, 45147 Essen, Germany.
⁸ Department of Neurosurgery, Centre of Neuro-Oncology, Jena University Hospital, Friedrich-Schiller-University Jena, 07747 Jena, Germany.
⁹ Institut für Physikalische Biologie, Heinrich-Heine-University Duesseldorf, 40225 Duesseldorf, Germany.
¹⁰ Department of Neurosurgery, University Hospital Bonn, 53127 Bonn, Germany.
¹¹ Department of Molecular and Experimental Surgery, Clinic of General, Visceral, Vascular and Transplant Surgery, Faculty of Medicine, Otto-von-Guericke University and University Hospital Magdeburg, 39120 Magdeburg, Germany.
¹² Department of Surgical Sciences, University of Otago, Dunedin 9054, New Zealand.

Abstract

Cancer stem-like cells mediate tumor initiation, progression, and therapy resistance; however, their identification and selective eradication remain challenging. Herein, we analyze the metabolic dependencies of glioblastoma stem-like cells (GSCs) with high-resolution proton nuclear magnetic resonance (¹H-NMR) spectroscopy. We stratify our in vitro GSC models into two subtypes primarily based on their relative amount of glutamine in relationship to glutamate (Gln/Glu). Gln/Glu^High GSCs were found to be resistant to glutamine deprivation, whereas Gln/Glu^Low GSCs respond with significantly decreased in vitro clonogenicity and impaired cell growth. The starvation resistance appeared to be mediated by an increased expression of the glutamate/cystine antiporter SLC7A11/xCT and efficient cellular clearance of reactive oxygen species (ROS). Moreover, we were able to directly correlate xCT-dependent starvation resistance and high Gln/Glu ratios with in vitro clonogenicity, since targeted differentiation of GSCs with bone morphogenic protein 4 (BMP4) impaired xCT expression, decreased the Gln/Glu ratio, and restored the sensitivity to glutamine starvation. Moreover, significantly reduced levels of the oncometabolites lactate (Lac), phosphocholine (PC), total choline (tCho), myo-inositol (Myo-I), and glycine (Gly) were observed in differentiated GSCs. Furthermore, we found a strong association between high Gln/Glu ratios and increased expression of Zinc finger E-box-binding homeobox 1 (ZEB1) and xCT in primary GBM tumor tissues. Our analyses suggest that the inhibition of xCT represents a potential therapeutic target in glioblastoma; thus, we could further extend its importance in GSC biology and stress responses. We also propose that monitoring of the intracellular Gln/Glu ratio can be used to predict nutrient stress resistance.

Keywords: NMR spectroscopy; ZEB1; cancer stem cells; glioblastoma; glutamine; metabolism; oncometabolites; xCT.