Adenosine receptors regulate exosome production

Exosomes, small-sized extracellular vesicles, carry components of the purinergic pathway. The production by cells of exosomes carrying this pathway remains poorly understood. Here, we asked whether type 1, 2A, or 2B adenosine receptors (A 1 Rs, A 2A Rs, and A 2B Rs, respectively) expressed by producer cells are involved in regulating exosome production. Preglomerular vascular smooth muscle cells (PGVSMCs) were isolated from wildtype, A 1 R −/− , A 2A R −/− , and A 2B R −/− rats, and exosome production was quantified under normal or metabolic stress conditions. Exosome production was also measured in various cancer cells treated with pharmacologic agonists/antagonists of A 1 Rs, A 2A Rs, and A 2B Rs in the presence or absence of metabolic stress or cisplatin. Functional activity of exosomes was determined in Jurkat cell apoptosis assays. In PGVSMCs, A 1 R and A 2A R constrained exosome production under normal conditions ( p = 0.0297; p = 0.0409, respectively), and A 1 R, A 2A R, and A 2B R constrained exosome production under metabolic stress conditions. Exosome production from cancer cells was reduced ( p = 0.0028) by the selective A 2A R agonist CGS 21680. These exosomes induced higher levels of Jurkat apoptosis than exosomes from untreated cells or cells treated with A 1 R and A 2B R agonists ( p = 0.0474). The selective A 2A R antagonist SCH 442416 stimulated exosome production under metabolic stress or cisplatin treatment, whereas the selective A 2B R antagonist MRS 1754 reduced exosome production. Our findings indicate that A 2A Rs suppress exosome release in all cell types examined, whereas effects of A 1 Rs and A 2B Rs are dependent on cell type and conditions. Pharmacologic targeting of cancer with A 2A R antagonists may inadvertently increase exosome production from tumor cells.