Production of Adenosine by Ectonucleotidases: A Key Factor in Tumor Immunoescape

Figure 2

Hypoxia mediated expression of ectonucleotidases and adenosine receptors. HIF is induced under hypoxic conditions in cancer cells and directly increases the expression of (1) ectonucleotidases CD39 and CD73, which generate adenosine from ATP/ADP, (2) adenosine receptors that could, after binding of adenosine, activate HIF, and (3) angiogenic molecules VEGF and IL-8. These (again with 𝛽-FGF) also produced by endothelial cells (through binding of adenosine on specific receptors) could induce proliferation of these cells.