Fig. 1
The two ectonucleotidases CD39 and CD73 control the metabolic fate of ATP and adenosine in the extracellular environment. Extracellular ATP is converted into its metabolites ADP and AMP sequentially by CD39, which is then further metabolized to adenosine by CD73. Activated CD39/CD73/A2AR signaling within the TME will suppress the function of antitumor immune cells (T cells, B cells, NK cells, and DCs) but promote the activity of the regulatory immune cells (MDSCs and Tregs), thus giving rise to a immunosuppressive TME. Notes: TME: tumor microenvironment; NK: natural killer; DCs: dendritic cells; MDSC: myeloid-derived suppressor cells; Treg: regulatory T cells; Th17: T helper 17 cells