Triggering of the TRPV2 channel by cannabidiol sensitizes glioblastoma cells to cytotoxic chemotherapeutic agents.

The aggressive behavior of Glioblastoma multiforme (GBM) is mainly due to high invasiveness and proliferation rate as well as to high resistance to standard chemotherapy. Several chemotherapeutic agents like temozolomide (TMZ), carmustine (BCNU) or doxorubicin (DOXO) have been employed for treatment of GBM, but they display limited efficacy. Therefore, it is important to identify new treatment modalities to improve therapeutic effects and enhance GBM chemosensitivity. Recently, activation of the transient receptor potential vanilloid type 2 (TRPV2) has been found to inhibit human GBM cell proliferation and overcome BCNU resistance of GBM cells. Herein, we evaluated the involvement of cannabidiol (CBD)-induced TRPV2 activation, in the modulation of glioma cell chemosensitivity to TMZ, BCNU and DOXO. We found that CBD increases TRPV2 expression and activity. CBD by triggering TRPV2-dependent Ca(2+) influx increases drug uptake and synergizes with cytotoxic agents to induce apoptosis of glioma cells, whereas no effects were observed in normal human astrocytes. Moreover, as the pore region of transient receptor potential (TRP) channels is critical for ion channel permeation, we demonstrated that deletion of TRPV2 poredomain inhibits CBD-induced Ca(2+) influx, drug uptake and cytotoxic effects. Overall, we demonstrated that co-administration of cytotoxic agents together with the TRPV2 agonist CBD increases drug uptake and parallelly potentiates cytotoxic activity in human glioma cells.