The P2X7 Receptor in Cancer: From Functional Receptor to Non-Functional P2X7

Abstract

The ATP-gated P2X7 receptors are abundantly expressed in immune cells, neurons, glial cells, and cancer cells. The P2X7 receptor performs distinct functions, depending on the extracellular ATP concentration and the duration of exposure to ATP. With brief ATP stimulation, the P2X7 receptor acts as an ion channel, and the movement of ions is associated with the regulation of cell proliferation and differentiation. Prolonged ATP exposure induces a conformational change in P2X7, allowing large molecules to pass through the membrane via the formation of macropores, thereby contributing to cell death. A novel function of P2X7 as a scavenger receptor was recently reported in the absence of both serum and ATP. However, the discovery of non-functional P2X7 in cancer reveals that this group of isoforms of P2X7 fails to form macropores upon ATP stimulation and cannot initiate ATP-induced cell death, allowing malignant cells to evade this regulatory mechanism and continue proliferating. We discuss the multifaceted functions of the P2X7 receptor in regulating diverse cell types, including cell growth, death, and clearance, and how the non-functional form of P2X7 disrupts this balance in cancer. Furthermore, the review explores the potential targeting of this aberrant isoform of P2X7 in the development of novel cancer therapies.