V-ATPase Sub-Classifies IDHwt Lowergrade Gliomas and Directs Extracellular Signaling Through Large Oncosomes and Homeobox Genes

Cancer cells use specific V-ATPase subunits to activate oncogenic pathways. We investigated deregulation of V-ATPase and associated signaling in aggressive gliomas. In vivo, we found that V-ATPase subunit expression correlates with glioma growth. Using patients' series, we observed that glioblastoma (GBM) and relapsed gliomas display a specific V-ATPase signature. Such signature resolves the heterogeneous class of IDH-wild type lower-grade gliomas, identifying the patients with worse prognosis.  Molecularly, GBM-like V-ATPase expression correlated with switch in epigenetic enzymes and upregulation of homeobox genes. GBM neurospheres influenced the non-neoplastic microenvironment by delivering the V-ATPase subunit V1G1 and homeobox genes HOXA7, HOXA10, and POU3F2 to recipient cells via large oncosomes (LO). LO reprogrammed recipient cells to grow as spheres and to migrate. Moreover, LO were particularly abundant in the circulation of GBM and of patients who died during follow-up. Finally, impairment of V-ATPase reduced LO activity.  These data identify a global cell fate change that underlies glioma aggressiveness and suggest new entry points for glioma stratification, follow-up, and therapy. Funding Statement: This work was supported by Fondazione Cariplo (2014-1148 to VV), Fondazione IRCCS Ca’ Granda, and Fondazione INGM Grant in Molecular Medicine 2014 (to VV) and by the Ricerca Corrente program 2017 (to SF). AMS and MF were supported by a Fellowship from the Doctorate School in Molecular and Translational Medicine of Milan University. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: Animal experiments were carried out in compliance with the institutional guidelines for the care and use of experimental animals (European Directive 2010/63/UE and the Italian law 26/2014), authorized by the Italian Ministry of Health and approved by the Animal Use and Care Committee of the University of Milan. The patient series of the study: The study was approved by an Institutional Review Board (IRB#275/2013) and signed informed consent was obtained from all patients.