ABSTRACT
ATP and adenosine (ADO) are critical players in the context of cancer. In the tumor microenvironment, the signaling dependent on these molecules, and immune cells, is regulated by an enzymatic chain and purinergic receptors called purinome. Primarily, the A2A receptor (A2AR) has a pro-tumor action since it reduces the immune response and favors the growth of malignant melanoma. Therefore, this study aimed to verify the effects of A2AR antagonism with Istradefylline (IST) on the purinergic signaling profile of the melanoma tumor and immunological compartments. We observed reduced tumor growth of melanoma in IST-treated animals. IST inhibited AKT/mTOR pathway, which is involved with tumor growth. In the tumor, spleen, and thymus, the modulation of purinergic enzymes (CD39, CD73, and E-ADA) characterized a pro-inflammatory profile since it favored increased extracellular concentrations of ATP to the detriment of ADO. A2AR inhibition generated a compensatory feedback process with increased A2AR expression at the tumor level. However, there was also an increase in the expression of the P2X7 receptor (P2X7R), which culminated in an increase in pro-inflammatory pathways with the release of IL-1ß and pro-inflammatory cytokines such as IFN-γ and TNF-α. Our data evidence the cross-involvement between expression and action of the A2AR and P2X7R. We suggest that IST is a promising drug for off-label use in cancer since it promotes an anti-tumoral response by producing pro-inflammatory cytokines and blocking of AKT/mTOR tumor growth pathway.
