Basic Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Stem Cells. Nov 26, 2020; 12(11): 1410-1428
Published online Nov 26, 2020. doi: 10.4252/wjsc.v12.i11.1410
Glutathione metabolism is essential for self-renewal and chemoresistance of pancreatic cancer stem cells
Petra Jagust, Sonia Alcalá, Bruno Sainz Jr, Christopher Heeschen, Patricia Sancho
Petra Jagust, Molecular Pathology Programme, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
Sonia Alcalá, Bruno Sainz Jr, Department of Biochemistry, Autónoma University of Madrid, Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-UAM, Madrid 28029, Spain
Christopher Heeschen, Center for Single-Cell Omics & Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
Patricia Sancho, Hospital Universitario Miguel Servet, IIS Aragon, Zaragoza 50009, Spain
Author contributions: Jagust P and Sancho P performed the experiments, acquired and analyzed data; Alcalá S and Sainz Jr B compiled and validated the samples for RNAseq analysis; Heeschen C and Sancho P interpreted data, designed the study and wrote the manuscript; all authors approved the final version of the manuscript.
Supported by ERC Advanced Investigator Grant, No. Pa-CSC 233460; European Community's Seventh Framework Programme, No. 602783; Instituto de Salud Carlos III and European Funds (FSE: “el FSE invierte en tu futuro” and FEDER: “una manera de hacer Europa”) Miguel Servet Fellowship, No. CP16/00121; and Fondo Investigaciones Sanitarias, No. PI17/00082.
Institutional review board statement: The study was reviewed and approved by the IIS Aragon Institutional Review Board.
Conflict-of-interest statement: Authors declare no conflict of interest.
Data sharing statement: RNAseq dataset E-MTAB-3808 is available at https://www.ebi.ac.uk/arrayexpress/.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Patricia Sancho, PhD, Senior Scientist, Hospital Universitario Miguel Servet, IIS Aragon, Isabel la Católica 1-3, Zaragoza 50009, Spain. psancho@iisaragon.es
Received: July 10, 2020
Peer-review started: July 10, 2020
First decision: August 9, 2020
Revised: August 19, 2020
Accepted: September 25, 2020
Article in press: September 25, 2020
Published online: November 26, 2020
Processing time: 139 Days and 0.8 Hours
ARTICLE HIGHLIGHTS
Research background

Redox metabolism modulates stem cell and cancer stem cell (CSC) functionality in different model systems, regardless of their dominant metabolic phenotype.  In fact, CSCs from several cancer types show increased glutathione content and associated enzymes.

Research motivation

Identification of metabolic vulnerabilities of highly aggressive CSCs can lead to the development of more effective treatment strategies for pancreatic cancer.

Research objectives

The present study aimed to determine the importance of glutathione metabolism for pancreatic CSCs as compared to their differentiated counterparts.

Research methods

Comparisons between CSCs and non-CSCs in primary pancreatic cancer cells of patient-derived xenografts were carried out by culturing in adherent or CSC-enriching sphere conditions and confirmed by CD133 staining by flow cytometry.  Gene expression analyses were performed by RNAseq or real-time PCR. Public TCGA and GTEx RNAseq data from pancreatic cancer vs normal tissue samples were analyzed using the webserver GEPIA2. Staining for measurement of glutathione (monochlorobimane), cell cycle (propidium iodide) or apoptosis (Annexin-V) were determined by fluorimetry or flow cytometry. Pharmacological glutathione depletion was achieved with inhibitors of glutathione synthesis (buthionine-sulfoximine) and recycling (6-Aminonicotinamide). Self-renewal was assessed by sphere formation assay and response to gemcitabine treatment was used as a readout for chemoresistance.

Research results

Several glutathione metabolism genes were upregulated in pancreatic CSCs, and their expression correlates with a stemness signature and predicts survival in clinical samples. Increased glutathione concentration in CSCs promotes viability, cell cycle progression and pluripotency gene expression. Inhibition of glutathione synthesis or recycling impairs CSC functionalities such as self-renewal and chemoresistance.

Research conclusions

Our data suggest that pancreatic CSCs depend on glutathione metabolism. Pharmacological targeting of this pathway showed that high GSH (glutathione in its reduced form) content is essential to maintain CSC functionality in terms of self-renewal and chemoresistance.

Research perspectives

Our data demonstrate a targetable metabolic vulnerability of this aggressive subpopulation of cancer cells, which could be exploited for therapeutic purposes.