Targeting mitochondria for therapies against MYCN-amplified neuroblastoma

High-risk neuroblastoma (NB) is a lethal pediatric solid tumor, with half of these cases driven by MYCN gene amplification (MNA). These tumors typically require high-dose chemotherapy, yet they frequently relapse, and current treatments are associated with severe long-term side effects. As MYCN, like many transcription factors, is considered undruggable, there is an urgent need for new therapies. Therefore, identifying and targeting downstream effector pathways presents a promising alternative approach for therapeutic intervention. MYCN drives various effects in the tumorigenic cell, including metabolic modifications that are essential for oncogenesis. Preliminary data from our group suggest that MYCN might regulate mitochondrial function, and that a complex I inhibitor of the mitochondria is effective against MNA cells in a MYCN-dependent fashion. Therefore, this project is built around the hypothesis that we can inhibit MNA NB growth by targeting mitochondrial function. In the first results chapter, we investigated the role of MYCN in the mitochondria of MNA cells. We performed proteomics and high-throughput microscopy analysis to uncover the binding partners of MYCN associated with mitochondrial regulation. Additionally, we assessed the effect of varying MYCN levels on mitochondrial function to understand how MYCN mediates its oncogenic effects in MNA NB. In the second chapter, we characterized the vulnerability of MNA cells to Diphenyleneiodonium chloride (DPI), a complex I inhibitor previously identified in a drug screen. Lastly, in chapter 3, we investigated a novel combination therapeutic approach targeting the metabolic vulnerabilities of MNA NB cells. By serendipity, we discovered that DPI synergizes with mitoquinone mesylate (MitoQ), a mitochondria targeted antioxidant in 2D and 3D in vitro odels of NB. In vivo experiments are currently being conducted to assess the efficacy of the triple combination in a transgenic mouse model of NB. Overall, this work demonstrates that interference with mitochondrial metabolism may represent an effective strategy to enhance the activity of chemotherapeutic drugs in MNA-NB. Moreover, we highlight key MYCN interactors that could potentially become drug targets.