TM-02 * IDENTIFICATION OF THE AZOLE CLASS OF ANTIFUNGALS AS POTENT INHIBITORS OF HEXOKINASE II MEDIATED TUMOUR METABOLISM IN GLIOBLASTOMA

Abstract

Rapidly proliferating tumour cells preferentially use aerobic glycolysis over oxidative phosphorylation (OXPHOS) to support growth and survive unfavorable microenvironment conditions. This metabolic reprogramming is referred to as the “Warburg effect” and offers a novel way to target cancer cells including glioblastoma (GBM), the most common malignant brain tumor. Here we demonstrate that Hexokinase 2 (HK2) but not HK1 or HK3 is a critical mediator of metabolic reprograming in GBMs and its inhibition is a potential therapeutic strategy for sensitization of GBM tumors to radiation (RAD) and temozolomide (TMZ). In GBM xenografts, conditional HK2 loss sensitizes tumors to concomitant RAD/TMZ and results in a significant survival benefit. Loss of HK2 resulted in increased necrosis, hypoxia, inflammatory infiltration and reduced vascularization. Currently, no direct inhibitor of HK2 exists so we explored whether a system biology approach to identify gene networks associated with HK2 could lead to the identification of HK2 inhibitors. Using HK2 knockdown in established GBM cell lines and primary cultures we established gene signatures and networks associated with HK2 expression. Loss of HK2 led to attenuation of several pro GBM signaling pathways affecting tumour cell invasion, glucose metabolism and proliferation. Using a small drug screen targeting potential HK2 regulated gene expression networks we identified the azole class of antifungals as inhibitors of tumour metabolism by reducing proliferation, lactate production, glucose uptake in GBM cells but not primary normal human astrocytes or normal neural stem cells. Interestingly, several azole compounds were more potent at killing GBM cells in hypoxic conditions. Azoles in combination with further HK2 knockdown, RT or in combination with other metabolic therapeutics including pyruvate kinase M2 (PKM) activators led to synergistic tumour cell death. In summary, the azole class of antifungals may represent a new way of targeting tumour metabolism in tumours dependent on aerobic glycolysis.