Mitochondria electron transport chain complexes adaptative responses to cellular stress

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PROJECT SUMMARY Radiotherapy is the most effective nonsurgical treatment for glioblastoma; however, therapeutic efficacy is severely limited due to the development of radioresistance (RR). In the hope of overcoming this urgent clinical problem, significant research has focused on defining the molecular mechanisms underlying RR. The overall objective of this application is to confirm the assembly of the ETC into mitochondrial respiratory supercomplexes (SCs) as a novel mechanism of RR. The central hypothesis of this proposal is that RR in GBM is the result of a rearrangement of the ETC complexes into SCs triggered by the expression of COX4-1, which promotes reprograming of glioma cell bioenergetics from predominantly aerobic glycolysis to mitochondrial oxidative phosphorylation and, consequently, reduces the mitochondrial production of reactive oxygen species (ROS). The specific aims proposed will use established glioma cell lines, patient-derived xenograft lines, preclinical animal models, and patient tumor samples to rigorously assess the validity of this hypothesis. Aim 1 will determine the role of CcO in SC assembly and mitochondrial metabolism. Aim 2 will evaluated the effects of SC on the regulation of ROS. Aim 3 will evaluate the role of SCs in the response of IR. We expect that data generated will vertically advance our understanding of how respiratory SCs affect outcomes in GBM and reveal the therapeutic vulnerability in RR GBM than can be exploited by SC- disrupting agents.