Extracellular ATP is increased by release of ATP-loaded microparticles triggered by nutrient deprivation

• Published in: Theranostics Vol. 12; no. 2; pp. 859 - 874
• Main Authors: Vultaggio-Poma, Valentina, Falzoni, Simonetta, Chiozzi, Paola, Sarti, Alba Clara, Adinolfi, Elena, Giuliani, Anna Lisa, Sánchez-Melgar, Alejandro, Boldrini, Paola, Zanoni, Michele, Tesei, Anna, Pinton, Paolo, Di Virgilio, Francesco
• Format: Journal Article
• Language: English
• Published: Australia Ivyspring International Publisher Pty Ltd 2022; Ivyspring International Publisher
• Subjects: Adenosine Triphosphate - metabolism; Animals; Caloric Restriction; Cancer; Cell culture; Cell growth; Cell-Derived Microparticles - drug effects; Cell-Derived Microparticles - metabolism; Citrates - pharmacology; Colonic Neoplasms - metabolism; Dehydrogenases; Extracellular Space - metabolism; Male; Melanoma; Melanoma - metabolism; Metabolism; Mice; Mice, Inbred C57BL; Mitochondria; Mitochondria - metabolism; Neoplasms - metabolism; Nutrients; Potassium; Reagents; Research Paper; Tumor Cells, Cultured; United States > US; Italy; microparticles; tumor microenvironment; P2X7; nutrient deprivation; extracellular ATP
• ISSN: 1838-7640; 1838-7640
• DOI: 10.7150/thno.66274

: Caloric restriction improves the efficacy of anti-cancer therapy. This effect is largely dependent on the increase of the extracellular ATP concentration in the tumor microenvironment (TME). Pathways for ATP release triggered by nutrient deprivation are largely unknown.
The extracellular ATP (eATP) concentration was
measured in the tumor microenvironment of B16F10-inoculated C57Bl/6 mice with the pmeLuc probe. Alternatively, the pmeLuc-TG-mouse was used. Caloric restriction was
induced with hydroxycitrate (HC). B16F10 melanoma cells or CT26 colon carcinoma cells were
exposed to serum starvation to mimic nutrient deprivation. Energy metabolism was monitored by Seahorse. Microparticle release was measured by ultracentrifugation and by Nanosight.
: Nutrient deprivation increases eATP release despite the dramatic inhibition of intracellular energy synthesis. Under these conditions oxidative phosphorylation was dramatically impaired, mitochondria fragmented and glycolysis and lactic acid release were enhanced. Nutrient deprivation stimulated a P2X7-dependent release of ATP-loaded, mitochondria-containing, microparticles as well as of naked mitochondria.
: Nutrient deprivation promotes a striking accumulation of eATP paralleled by a large release of ATP-laden microparticles and of naked mitochondria. This is likely to be a main mechanism driving the accumulation of eATP into the TME.