Protective Properties of Radio-Chemoresistant Glioblastoma Stem Cell Clones Are Associated with Metabolic Adaptation to Reduced Glucose Dependence.

Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
PLoS ONE (Impact Factor: 3.53). 11/2013; 8(11):e80397. DOI: 10.1371/journal.pone.0080397
Source: PubMed

ABSTRACT Glioblastoma stem cells (GSC) are a significant cell model for explaining brain tumor recurrence. However, mechanisms underlying their radiochemoresistance remain obscure. Here we show that most clonogenic cells in GSC cultures are sensitive to radiation treatment (RT) with or without temozolomide (TMZ). Only a few single cells survive treatment and regain their self-repopulating capacity. Cells re-populated from treatment-resistant GSC clones contain more clonogenic cells compared to those grown from treatment-sensitive GSC clones, and repeated treatment cycles rapidly enriched clonogenic survival. When compared to sensitive clones, resistant clones exhibited slower tumor development in animals. Upregulated genes identified in resistant clones via comparative expression microarray analysis characterized cells under metabolic stress, including blocked glucose uptake, impaired insulin/Akt signaling, enhanced lipid catabolism and oxidative stress, and suppressed growth and inflammation. Moreover, many upregulated genes highlighted maintenance and repair activities, including detoxifying lipid peroxidation products, activating lysosomal autophagy/ubiquitin-proteasome pathways, and enhancing telomere maintenance and DNA repair, closely resembling the anti-aging effects of caloric/glucose restriction (CR/GR), a nutritional intervention that is known to increase lifespan and stress resistance in model organisms. Although treatment-introduced genetic mutations were detected in resistant clones, all resistant and sensitive clones were subclassified to either proneural (PN) or mesenchymal (MES) glioblastoma subtype based on their expression profiles. Functional assays demonstrated the association of treatment resistance with energy stress, including reduced glucose uptake, fatty acid oxidation (FAO)-dependent ATP maintenance, elevated reactive oxygen species (ROS) production and autophagic activity, and increased AMPK activity and NAD(+) levels accompanied by upregulated mRNA levels of SIRT1/PGC-1α axis and DNA repair genes. These data support the view that treatment resistance may arise from quiescent GSC exhibiting a GR-like phenotype, and suggest that targeting stress response pathways of resistant GSC may provide a novel strategy in combination with standard treatment for glioblastoma.

1 Bookmark
  • [Show abstract] [Hide abstract]
    ABSTRACT: Primary cell lines derived as neurospheres, enriched in cancer stem cells, are currently the focus of interest in glioblastoma to test new drugs, because of their tumor initiating abilities and resistance to conventional therapies. However, not all glioblastoma samples are propagatable under neurosphere culture and not all neurosphere cell lines are tumorigenic. These cells therefore cannot recapitulate the heterogeneity of glioblastoma samples. We have conducted a proteomic analysis of primary glioblastoma cell lines derived either as adherent cells in the presence of serum (n=11) or as neurospheres (n=12). A total of 963 proteins were identified by nano-LC/Q-TOF MS: 342 proteins were only found in neurosphere lines and were mostly implicated in various metabolic and cellular processes, while 112 proteins were only found in adherent cells and mostly linked to cell adhesion. A protein signature of 10 proteins, 9 of them involved in a cell adhesion pathway, characterized adherent lines. Neurospheres were characterized by 73 proteins mostly linked to DNA metabolic processes associated to cell cycle and protein metabolism. In the Repository of Molecular Brain Neoplasia Data, expression of genes coding for several proteins related to adherent cells or neurospheres were of prognostic relevance for glioblastoma.
    Journal of Proteomics 07/2014; · 3.93 Impact Factor

Full-text (2 Sources)

Available from
Jul 30, 2014