De Marchi, E. | bioRxiv Science

bioRxiv2022

A2A Receptor contributes to tumor progression in P2X7 null mice

ATP and adenosine are key constituents of the tumor niche where they exert opposite and complementary roles. ATP promotes tumor growth but also immune eradicating responses mainly via the P2X7 receptor (P2X7R), while adenosine acts as a potent immune suppressor and facilitates neovascularization thanks to A2A receptor (A2AR) activity. However, studies exploring the interplay between P2X7R and A2AR in the tumor microenvironment are as yet missing. Here we investigated tumor growth in C57/bl6 P2X7 null mice inoculated with B16-F10 melanoma cells, showing that several pro-inflammatory cytokines (IL1-{beta}, TNF-, IL-6, IL-12, IL-17, IFN-{gamma}) were significantly decreased while the immune suppressant TGF-{beta} was almost three-fold increased. Interestingly, tumors growing in P2X7-null mice also upregulated tumor-associated and splenic A2AR, suggesting that immunosuppression associated to lack of the P2X7R might depend upon A2AR overexpression. Immunohistochemical analysis showed that tumor cells A2AR expression was increased, especially around necrotic areas, and that VEGF and the endothelial marker CD31 were also upregulated. The A2AR antagonist SCH-58261 reduced tumor growth similarly in the P2X7 WT, or null mice strain. However, SCH-58261only reduced VEGF in the P2X7-KO mice, thus supporting the hypothesis of an A2AR mediated increase in vascularisation in P2X7-null host. SCH-58261 administration also significantly reduced intratumor TGF-{beta}, thus supporting a key immune suppressive role of A2AR in our model. This study shows a novel direct correlation between P2X7R and A2AR in oncogenesis and paves the way for new combined therapies promoting anti-cancer immune responses and reducing tumor vascularization.

cancer biology↗

bioRxiv2021

The P2RX7B splice variant modulates osteosarcoma cell behaviour and metastatic properties

Osteosarcoma (OS) is the most common type of primary bone cancer affecting children and adolescents. OS has a high propensity to spread, meaning the disease is often incurable and fatal. There have been no improvements in survival rates for decades. This highlights an urgent need for development of novel therapeutic strategies. In this study, we have produced in vitro and in vivo data that demonstrates the role of purinergic signalling, specifically, the B isoform of the purinergic receptor P2RX7 (herein termed " P2RX7B"), in OS progression and metastasis. Our data shows that P2RX7B expression confers a survival advantage in TE85+P2RX7B and MNNG-HOS+ P2RX7B human OS cell lines in vitro that is minimised following treatment with A740003, a specific P2RX7 antagonist. P2RX7B expression reduced cell adhesion and P2RX7B activation promoted invasion and migration in vitro, suggesting a probable metastatic phenotype. Using an in vivo OS xenograft model, MNNG-HOS+P2RX7B tumours exhibited ectopic bone formation that was abrogated with A740003 treatment. An increased metastatic phenotype was further demonstrated in vivo as expression of P2RX7B in primary tumour cells increased the propensity of the tumour to metastasise to the lungs. RNA-seq identified a novel gene axis, FN1/LOX/PDGFB/IGFBP3/BMP4, downregulated in response to A740003 treatment. In conclusion, our data indicates for the first time a role for P2RX7B in OS tumour growth, progression and metastasis. We show that P2RX7B is a potential therapeutic target in human OS. Novelty and ImpactWe provide evidence for the pro-tumorigenic role of the B isoform of the P2RX7 purinergic receptor in osteosarcoma (OS). In addition to increasing proliferation, P2RX7B increases the cancerous properties of OS cells, reducing adhesion and increasing migration and invasion. In vivo, P2RX7B does not affect primary tumour growth, but does lead to an increased propensity to metastasize. RNA-seq revealed a new axis of oncogenic genes inhibited by the P2RX7 antagonist and this data could potentially lead to new targets for OS treatment.

cancer biology↗