Hypermethylation downregulates P2X(7) receptor expression in astrocytoma

The present study investigated the altered expression of p2X purinoceptor (P2X(7)R) in astrocytoma. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were used to determine the P2X(7)R expression in glioblastoma (GBM) and surrounding normal brain tissue. DNA methylation levels of P2X(7)R gene promoter in GBM were analyzed using a Sequenom MassARRAY(®) System. Immunohistochemistry (IHC) was used to detect the expression of P2X(7)R in astrocytoma at different malignancy grades, including diffuse astrocytoma, anaplastic astrocytoma and GBM. P2X(7)R mRNA and protein were significantly decreased in GBM compared with normal brain tissues. IHC results showed a negative correlation between P2X(7)R expression and tumor grade. The decreased P2X(7)R expression was mostly attributed to hypermethylation of its promoter. Therefore, P2X(7)R was found to perform an important role in tumorigenesis and progression of astrocytoma.