TM-01 * IDENTIFICATION OF GLUCOSE-6-PHOSPHATASE ALPHA AS A KEY METABOLIC REGULATOR FOR GLIOBLASTOMA CELL INVASION

Abstract

Glioblastoma (GBM) remains the most aggressive primary brain cancer in adults. Similar to other cancers, GBM cells undergo metabolic reprogramming to promote proliferation and survival. Glycolytic inhibition is widely used to target such reprogramming. However, the stability of glycolytic inhibition in GBM remains unclear. In this study, we found that the expression of glucose-6-phosphatase-α (G6PC) was elevated in GBM when compared to normal brain ) (p < 0.001). Human-derived brain tumor initiating cells (BTICs) utilize this enzyme to counteract glycolytic inhibition induced by 2-Deoxy-D-glucose (2DG) and sustain malignant progression. Down-regulation of G6PC renders the majority of these cells unable to survive glycolytic inhibition, and promotes glycogen accumulation through the activation of glycogen synthase (GYS1) and inhibition of glycogen phosphorylase (PYGL). Moreover, BTICs that survive G6PC knockdown are less aggressive (reduced migration, invasion, proliferation, and increased astrocytic differentiation) (p < 0.001). Interestingly, after performing immunohistochemistry staining for G6PC in brain sections derived from animals implanted with G6PC knockdown cells for a survival study, we found a complete rescue of its expression in the tumor cells of these animals. These results explain the absence of survival differences observed between G6PC knockdown and wild type mice. Furthermore, these findings also suggest a very important role for G6PC in cell survival, since only the cells that carried G6PC where able to survive and invade in our animal model. Collectively, our findings establish G6PC as a key enzyme with pro-malignant functional consequences that has not been previously reported in GBM and identify it as a potential therapeutic target.