Colorectal Cancer and Purinergic Signalling: An Overview.

Colorectal cancer (CRC) is among the most common cancers and exhibits a high fatality rate. Gut inflammation is related to CRC, with loss of homeostasis in immune cell activities. The cells of the innate and adaptive immune system, including macrophages, neutrophils, mast cells, and lymphocytes, are present in most solid tumors. Purinergic signaling allows for communication between immune cells within the tumor microenvironment (TME) and can alter the TME to promote tumor progression. This system is regulated by the availability of extracellular purines to activate purinoceptors (P1 and P2) and is tightly controlled by ectonucleotidases (E-NPP, CD73/CD39, ADA) and kinases, which interact with and modify nucleotides and nucleosides availability. In this review, we compiled articles detailing the relationship of the purinergic system with CRC progression. We found that increased expression of CD73 leads to the suppression of effector immune cell functions and tumor progression in CRC. The P1 family purinoceptors A1, A2A, and A2B were positively associated with tumor progression, but A2B resulted in increased cancer cell apoptosis. The P2 family purinoceptors P2X5, P2X7, P2Y, P2Y, and P2Y were factors primarily associated with promoting CRC progression. In summary, CD39/CD73 axis and the purinergic receptors exhibit diagnostic and prognostic value and have potential as therapeutic targets in CRC.