Hypoxic extracellular vesicles (EVs) regulate mitochondrial metabolic reprogramming in neuroblastoma tumor via miR-210-3p

Neuroblastoma (NB) is a common childhood tumor arising from embryonic neural crest cells that can lead to widely metastatic disease. Mitochondria play a crucial role in cellular functions such as energy metabolism, survival, and proliferation. The reprogramming of mitochondrial metabolism is a hallmark of cancer, which contributes to the adaptation of fast-growing cancer cells to their increasing energy demands. Hypoxia, a condition of low oxygen tension, can directly regulate mitochondrial metabolism and composition. Tumor cells present in the hypoxic core extensive communicate with their microenvironment to establish favorable conditions for their survival, growth, and metastatic potential. The communication is facilitated by hypoxia-induced secretion of extracellular vesicles (EVs) that regulate mitochondrial function by releasing various cargos, such as growth factors, proteins, RNAs, microRNAs (miRNAs), and lipids. miRNAs, a class of small non-coding RNAs, are capable of regulating multiple cellular pathways including those related to differentiation, apoptosis, and stem cell maintenance. In this study we analyzed the effects of EVs isolated from SK-N-AS and IMR-32 NB cell lines cultured in normoxia (20% O2) and hypoxia (1.5% O2) conditions on naïve NB cells. We focused on EVs-mediated mitochondrial function regulation, and on its possible mechanisms. By analyzing metabolic fluxes through the mitochondria, we were able to demonstrate that vesicles produced by neuroblastoma cells under hypoxic conditions can regulate mitochondrial activity by reducing its oxygen consumption. To further investigate the mechanism by which molecules contained in hypoxic vesicles may induce such changes, we specifically analyzed the role of miR-210-3p, a miRNA whose levels are modulated by hypoxia, in the reprogramming of mitochondrial behavior by acting on potential downstream targets such as NDUFA4 and ISCU.