Synergistic combination of cannabidiol and celecoxib or 2,5-dimethylcelecoxib exerts oxidative stress-mediated cytotoxicity and mitigates glioblastoma invasiveness

Glioblastoma remains one of the most aggressive and treatment-resistant malignancies. Current treatment options, such as radio- and chemotherapy, induce oxidative stress-mediated DNA damage leading to cancer cell death, but are also neurotoxic and not efficient in long term. Our study investigated the effects of cannabidiol, celecoxib and 2,5-dimethylcelecoxib, individually and in combinations, on U-138 MG glioblastoma cell survival, oxidative stress, canonical and non-canonical Nrf2 pathway activation, cell migration and apoptosis. Using the MTT and flow cytometry assay we found that the analyzed compounds and their combinations induce dose-dependent, synergistic, and oxidative stress-related cytotoxicity, with minimal impact (at the concentrations exhibiting anti-cancer effects) on non-cancerous human astrocyte (HA) cell line. The Nrf2 ELISA assay was used for the analysis of the nuclear binding of the nuclear factor-2 erythroid related factor-2 (Nrf2), which followed by the RT-qPCR and Western blot analysis, confirmed the antioxidant response of cells to the applied treatments. Diminished migratory potential, and increase of the autophagy-related p62, LC3 and apoptosis-related caspase-3 protein levels were also observed in response to the treatment with the analyzed compounds. Overall, our study provides evidence that cannabidiol combined with celecoxib or 2,5-dimethylcelecoxib may represent a promising strategy for glioblastoma treatment.