Heat stress-activated P2X7 receptor induces astrocyte activation and regulates glioma tumor microenvironment via calcium signaling pathway.

BACKGROUND AND AIMS: The effects of adjuvant hyperthermia on glioblastoma-associated astrocytes remain poorly characterized. This study aimed to investigate the role of the purinergic P2X7 receptor, an ATP-gated ion channel, in mediating heat-induced astrocyte activation and its impact on tumor progression.

METHODS

Primary mouse astrocytes were subjected to heat stress (mild hyperthermia at 42°C). P2X7 signaling was examined using a specific antagonist (A-740003), siRNA-mediated knockdown, and live-cell calcium imaging. Astrocyte activation was evaluated by assessing Glial Fibrillary Acidic Protein (GFAP) expression and pro-inflammatory markers. The pro-tumorigenic potential of astrocyte-conditioned medium was tested on U87 glioblastoma cells. An orthotopic mouse model was used to validate the effects of local hyperthermia, with or without P2X7 inhibition.

RESULTS

Mild hyperthermia upregulated P2X7 expression in astrocytes and induced a substantial calcium influx, leading to activation of the Calcineurin-NFAT pathway. This process promoted a reactive astrocyte phenotype and a pro-tumorigenic secretory profile, enhancing U87 cell proliferation, migration, and invasion. In vivo, mild hyperthermia was associated with increased tumor progression, which was attenuated by pharmacological inhibition of P2X7.

CONCLUSION

Heat stress facilitates glioblastoma progression by activating astrocytes through the P2X7-mediated calcium-calcineurin-NFAT signaling pathway. These findings highlight P2X7 as a potential therapeutic target for optimizing hyperthermia-based strategies in glioblastoma treatment.