Gliomas are the most lethal
tumors of central nervous system.
ATP is an important signaling molecule in CNS and it is a selective P2X7
purinergic receptor ligand at high concentrations. Herein, we investigated whether the activation of P2X7R might be implicated in death of a radiosensitive human
glioma lineage. The effects of P2X7R agonists (
ATP and
BzATP) and irradiation (2 Gy) on
glioma cells were analyzed by MTT assay and
annexin-V/PI determination, whereas
mRNA and
protein P2X7R expression was assessed by qRT-PCR and flow cytometry, respectively. P2X7R pore formation was functionality examined by analyzing
ethidium bromide uptake. The human
glioma cells U-138 MG and U-251 MG were resistant to death when treated with either
ATP (5 mM) or
BzATP (100 μM), but the radiosensitive M059J
glioma cells displayed a significant decrease of cell viability (32.4 ± 4.1 % and 25.6 ± 3.3 %, respectively). The M059J lineage expresses significantly higher
mRNA P2X7R levels when compared to the U-138 MG and U-251 cell lines (0.40 ± 0.00; 0.28 ± 0.01, and 0.31 ± 0.01, respectively), and irradiation upregulated P2X7R expression (0.55 ± 0.08) in this lineage. Noteworthy, P2X7R
protein doubled after irradiation on M059J lineage, and increased in 50 % and 42.6 % when comparing M059J-irradiated to irradiated U-138 MG and U-251 MG cells, respectively.
Ethidium bromide uptake was significantly increased in 104 % and 77.8 % when comparing M059J to U-138 MG and U-251MG, respectively. Finally, the selective P2X7R antagonist
A740003 significantly decreased the cell death caused by irradiation. We provide novel evidence indicating that M059J human
glioma cell line is ATP-P2X7R sensitive, pointing out the relevance of the purinergic P2X7R on
glioma radiosensitivity.