P02.16.B COMPENSATORY CROSS-TALK BETWEEN AUTOPHAGY AND GLYCOLYSIS REGULATES SENESCENCE AND STEMNESS IN HETEROGENEOUS GLIOBLASTOMA TUMOR SUBPOPULATIONS
Journal Articles
Overview
Research
Identity
Additional Document Info
View All
Overview
abstract
AbstractBACKGROUNDDespite tremendous research efforts, the successful targeting of aberrant tumor metabolism in clinical practice has remained elusive. Tumor heterogeneity and metabolic plasticity may play a role in the clinical failure of metabolism-targeting interventions for treating cancer patients. Moreover, compensatory growth-related processes and adaptive responses exhibited by heterogeneous tumor subpopulations to metabolic inhibitors are poorly understood. Hence, a deeper understanding of the cellular adaptations in response to metabolic interventions is urgently required to develop more effective therapeutic options against deadly glioblastoma (GBM) brain tumors.MATERIAL AND METHODSUsing clinically-relevant patient-derived GBM models, we discovered a cross-talk between glycolysis, autophagy, and senescence. Protein and mRNA expression of glycolytic enzymes and stemness markers were measured using western blot and bioinformatic analysis, respectively. We were able to measure senescence with the use of β-galactosidase staining and upregulation of cell cycle regulators, such as p21/CDKN1A and p16/CDKN2A. Autophagy flux and EGFP-MAP1LC3B+ puncta formation analysis was used to determine autophagy induction.RESULTSWe found that stem cell-like GBM tumor subpopulations possessed higher basal levels of glycolytic activity and increased expression of several glycolysis-related enzymes including, GLUT1/SLC2A1, PFKP, ALDOA, GAPDH, ENO1, PKM2, and LDH, compared to their non-stem-like counterparts. Importantly, the mRNA expression of glycolytic enzymes positively correlates with stemness markers (CD133/PROM1 and SOX2) in patient GBM tumors. While treatment with glycolysis inhibitors induced senescence in stem cell-like GBM tumor subpopulations, these cells maintained their aggressive stemness features and failed to undergo apoptotic cell death. Moreover, we determined that inhibition of glycolysis led to the induction of autophagy in stem cell-like GBM tumor subpopulations, but not in their non-stem-like counterparts. Similarly, blocking autophagy in stem cell-like GBM tumor subpopulations induced senescence-associated growth arrest without hampering stemness capacity or triggering apoptosis while reciprocally upregulating glycolytic activity. Combinatorial treatment of stem cell-like GBM tumor subpopulations with autophagy and glycolysis inhibitors blocked the induction of senescence while drastically impairing their stemness capacity which drove cells towards apoptotic cell death.CONCLUSIONThese findings identify a novel and complex compensatory interplay between glycolysis, autophagy, and senescence that helps maintain stemness in heterogeneous GBM tumor subpopulations and provides a survival advantage during metabolic stress. This work was supported by the Cancer Research Society (CRS).
