Upregulation of Epithelial-To-Mesenchymal Transition Markers and P2X7 Receptors Is Associated to Increased Invasiveness Caused by P2X7 Receptor Stimulation in Human Glioblastoma Stem Cells

• Main Authors: Sihana Ziberi, Mariachiara Zuccarini, Marzia Carluccio, Patricia Giuliani, Lucia Ricci-Vitiani, Roberto Pallini, Francesco Caciagli, Patrizia Di Iorio, Renata Ciccarelli
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Cells
• Subjects: glioblastoma stem cells (gscs); epithelial-to-mesenchymal transition (emt) markers; gsc invasiveness; transforming growth factor beta; bzatp; p2x7 receptor splice variants a and b
• Online Access: https://www.mdpi.com/2073-4409/9/1/85

Glioblastoma (GBM) stem cells (GSCs), which contribute to GBM unfavorable prognosis, show high expression levels of ATP/P2X7 receptors (P2X7R). Here, we reported that cells exposure to 2&#8217;(3&#8217;)-<i>O</i>-(4-benzoylbenzoyl)-ATP (BzATP), a P2X7R agonist, up-regulated the expression of markers associated to epithelial-to-mesenchymal transition (EMT), a process likely contributing to GSC malignancy, and increased GSC migration/invasiveness like the known EMT inducer, Transforming Growth Factor &#946;1 (TGF&#946;1). These effects were coupled to phosphorylation of SMAD2, a downstream effector in the TGF&#946; pathway, suggesting its involvement in P2X7R-mediated activity in GSCs. All BzATP effects, including a decrease in the caspase 3/7 activity in GSC medium, were mostly counteracted by the P2X7R antagonist A438079. Finally, BzATP increased the subunit expression of two main human P2X7R splice variants, the full-length P2X7A and the truncated P2X7B, lacking the carboxylic tail, which have different functional properties depending on their arrangement. Since up-regulation of A/B subunits might favor their assembly into a heterotrimeric P2X7R with great sensitivity towards agonists and cell energy support, this is in line with increased EMT markers expression, cell migration/invasion and GSC survival observed following P2X7R stimulation. As in GBM microenvironment extracellular ATP levels may activate P2X7R, our data suggest a P2X7R role in GBM recurrence/invasiveness.