P2X4R silence suppresses glioma cell growth through BDNF/TrkB/ATF4 signaling pathway.

Purinergic receptor P2X 4 (P2X4R), a member of purinergic channels family and a subtype of ionotropic adenosine triphosphate receptors, plays a critical role in tumorigenesis. Evidence suggested that P2X4R is expressed in rat C6 glioma model, however, its role and the underlying mechanism of action are still unclear in human glioblastoma multiforme (GBM). In the current study, our aim is to examine the function and the molecular basis of P2X4R in GBM. We first observed that GBM cells, U251, T98, U87, U373, and A172 were all high expressed P2X4R, when compared with the normal human astrocytes (NHA) cells. To gain the function of P2X4R, P2X4R silence cells were constructed by transfection with P2X4R small interfering RNA (siRNA). We found that P2X4R deletion impeded T98 and U87 cell viability and proliferation, and further studies indicated that cell apoptosis and caspase-3 activity was increased in T98 and U87 cell transfected with P2X4R siRNA. Subsequently, we confirmed that P2X4R silence suppressed brain-derived neurotrophic factor (BDNF), Trk receptor tyrosine kinases (TrkB), and activating transcription factor 4 (ATF4) expression in T98 and U87 cells. And P2X4R siRNA-induced ATF4-expression inhibition dependent on BDNF/TrkB signaling pathway. The impact of P2X4R silence on T98 and U87 cell growth and apoptosis was reversed by ATF4 overexpression. In summary, this study provides the first evidence that P2X4R plays important roles in GBM cell growth and apoptosis.