title: V-ATPase is a candidate therapeutic target for Ewing sarcoma.
abstract: Suppression of oxidative phosphorylation combined with enhanced aerobic glycolysis and the resulting increased generation of protons are common features of several types of cancer. An efficient mechanism to escape cell death resulting from intracellular acidification is proton pump activation. In Ewing sarcoma (ES), although the tumor-associated chimeric gene EWS-FLI1 is known to induce the accumulation of hypoxia-induced transcription factor HIF-1α, derangements in metabolic pathways have been neglected so far as candidate pathogenetic mechanisms. In this paper, we observed that ES cells simultaneously activate mitochondrial respiration and high levels of glycolysis. Moreover, although the most effective detoxification mechanism of proton intracellular storage is lysosomal compartmentalization, ES cells show a poorly represented lysosomal compartment, but a high sensitivity to the anti-lysosomal agent bafilomycin A1, targeting the V-ATPase proton pump. We therefore investigated the role of V-ATPase in the acidification activity of ES cells. ES cells with the highest GAPDH and V-ATPase expression also showed the highest acidification rate. Moreover, the localization of V-ATPase was both on the vacuolar and the plasma membrane of all ES cell lines. The acidic extracellular pH that we reproduced in vitro promoted high invasion ability and clonogenic efficiency. Finally, targeting V-ATPase with siRNA and omeprazole treatments, we obtained a significant selective reduction of tumor cell number. In summary, glycolytic activity and activation of V-ATPase are crucial mechanisms of survival of ES cells and can be considered as promising selective targets for the treatment of this tumor.
authors.affiliation: Laboratory for Orthopaedic Pathophysiology and Regenerative Medicine, Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136, Bologna, Italy. sofia.avnet@ior.it
authors.forename: Sofia
authors.initials: S
authors.lastname: Avnet
authors.forename: Gemma
authors.initials: G
authors.lastname: Di Pompo
authors.forename: Silvia
authors.initials: S
authors.lastname: Lemma
authors.forename: Manuela
authors.initials: M
authors.lastname: Salerno
authors.forename: Francesca
authors.initials: F
authors.lastname: Perut
authors.forename: Gloria
authors.initials: G
authors.lastname: Bonuccelli
authors.forename: Donatella
authors.initials: D
authors.lastname: Granchi
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Zini
authors.forename: Nicola
authors.initials: N
authors.lastname: Baldini
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D048708:Cell Growth Processes / Q000187:drug effects; D002460:Cell Line; D019069:Cell Respiration / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006019:Glycolysis / Q000187:drug effects / Q000235:genetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D058990:Molecular Targeted Therapy; D017494:Proton Pumps / Q000235:genetics / Q000378:metabolism; D011522:Protons; D012512:Sarcoma, Ewing / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D018942:Macrolides; D017494:Proton Pumps; D011522:Protons; C040929:bafilomycin A1; D000251:Adenosine Triphosphatases