Project Summary: Glioblastoma multiforme is the most common primary brain tumor with about 8500 cases diagnosed each year in the United States. Within a time frame of 15 month virtually all patients succumb to this detrimental disease despite treatment efforts. Therefore, novel, ideally tumor specific approaches are necessary to combat these tumors. While single reagents may efficiently target other tumors, such as hematological malignancies, Glioblastoma is strikingly different since it is a tumor that is characterized by extensive heterogeneity, demanding the simultaneous inhibition of ideally several deregulated pathways. Our previous research has shown that targeting mitochondrial matrix chaperones displays significant anti-glioma effects. In this proposal, an accomplished team of investigators will be characterizing a novel treatment concept for glioblastoma by dual targeting of two deregulated pathways in tumor mitochondria. In the first specific aim we will test this novel treatment concept, utilizing several in vitro model systems of glioblastoma with a special focus on so called stem cell-like glioma cells, a population of tumor cells that drive therapeutic resistance in these neoplasms. Our preliminary data indicate that our treatment concept efficiently targets this pivotal cell population. In order to further improve our treatment concept we will study the cell death mechanisms involved in the combination treatment. In the second aim, we will characterize the mechanisms that are involved in this treatment approach, which is a centerpiece of our proposal and may further allow us to better understand and tailor treatments and potentially to stratify patients that in particular may benefit from this treatment approach. In the third specific aim we will test this treatment concept in current in vivo model systems of glioblastoma, which will extend our preliminary data that suggest that this treatment concept is active in vivo. Overall, this research may enhance our understanding about the treatment of brain tumors and may potentially allow us to formulate a novel treatment strategy for glioblastoma.