P2X7 receptor activity landscape in rat and human glioma cell lines

Abstract

P2X7 is a commonly expressed purinergic receptor, which functions as a cation-permeable channel in the plasma membrane. In certain circumstances, the receptor may also form a large transmembrane pore what results in cell death. P2X7 receptors control numerous physiological and pathological cellular processes and their overexpression is often associated with cancer progression. As nucleotides are important signaling molecules in the central nervous system, P2X7 plays also an important but ambiguous role in glioma biology with contrary observations originating from different glioma models. Therefore, the aim of our research was to investigate P2X7 receptor expression and functions in three human (U-87 MG, U-138 MG, U-251 MG) and one rat (C6) glioma cell lines. Although the receptor mRNA and protein were present in all the studied cells, we found profound differences in their level. We also encountered a problem with one human cell lines authenticity (U-87 MG) and excluded it from most of the experiments. Interestingly, there was no clear dependency between P2X7 receptor level, calcium signal and pore formation ability in the studied glioma lines. In U-138 human cell line, the receptor seemed to be inactive, while in U-251 human and C6 rat cell line its activation resulted in calcium influx and large pore formation. However, the viability of studied cells upon the administration of specific P2X7 agonist -BzATP -was not affected for U-138 and U-251, whereas for C6 cells a stimulatory effect was observed. Our results stress the variability of P2X7 signaling in glioma models and the need for future research which would take into account the complicated landscape of the receptor signaling in the brain.

Inhibition of purinergic P2X receptor 7 (P2X7R) decreases granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in U251 glioblastoma cells

“…The antibodies used have been validated previously in multiple studies 24,44,45 . These findings are consistent with previous published data that have demonstrated that P2X7R is present in other glioblastoma cell lines, human glioma samples and orthotopic glioma animal models 16,27,29,46 . The GM-CSF receptor consists of both an α and a β subunit which are necessary for receptor function and signaling 33 .…”

P2X7 receptor: the regulator of glioma tumor development and survival

“…Human glioma cell lines U-251 and U-138 are characterized by a low P2X7 expression when compared to rat glioma C6 cells, as was described previously [43]. Nevertheless, we observed an increase of p38 MAPK phosphorylation and increase of HSPA1 and CD133 protein level in U-138 glioma cells stimulated with 100 μM of BzATP for 24 h (Fig.…”

“…In our previous study, we did not observe P2X7 stimulant effect on human U-251 and U-138 glioma cell proliferation. Moreover, P2X7 receptor seemed to be inactive in U-138 glioma cells [43]. In the present study, we showed the stimulant effect of P2X7 on p38 MAPK phosphorylation and CD133 and HSPA1 expression in U-138 cells.…”

“…Continuous activation of P2X7 by BzATP led to an increase of P2X7 protein level in rat C6 glioma cells. The activation also promoted the pore formation, evidenced by ethidium bromide uptake, and increased calcium signal in C6 glioma cells [43]. Also, P2X7 activation stimulated massive extracellular ATP release from C6 cells into the culture medium.…”

Enteric nervous system and inflammatory bowel diseases: Correlated impacts and therapeutic approaches through the P2X7 receptor

“…In response to inflammation[ 14 , 128 ], trauma or injury[ 91 , 141 ], the elevation of ATP causes a prolonged stimulus that induces the transition of the ion channel to a nonselective membrane pore[ 101 , 142 , 143 ], making the cell permeable to molecules up to 900 daltons[ 94 , 101 , 142 , 143 ]. In association, massive calcium influx[ 144 ] can contribute to cell death[ 85 , 137 , 145 ], with subsequent release of greater amounts of ATP[ 146 - 148 ].…”