Pannexin 1 inhibition reduces tumorigenic properties of patient-derived glioblastoma cells through the HIPPO and Wnt signalling pathways

Glioblastoma multiforme (GBM) is the most prevalent type of primary brain tumor, with a median survival of merely 12-18 months, underscoring the urgent need for novel therapeutic targets. Researchers found that pannexin 1 (PANX1), a glycoprotein integral to purinergic signaling, is overexpressed in GBM as opposed to normal tissue and is present throughout the tumors in patients.

Analysis carried out on patient-derived GBM cell lines showed a significant increase in PANX1 expression within these primary lines when compared to brain tissue and glial cell controls. Gene expression analysis using bulk RNA-sequencing on GBM cells without PANX1, achieved through CRISPR/Cas9 deletion (PANX1-KO), versus control groups, showed that PANX1-KO in GBM cells impacts cell surface and junctional components, pathways, and processes, including the HIPPO pathway, as well as significantly reducing the mRNA levels of beta-catenin and other components of the Wnt pathway.

Elimination of PANX1 led to a disruption in the beta-catenin protein and a marked decrease in cell migration and proliferation. Pharmacological inhibition of PANX1 in GBM cells treated with probenecid (PBN) and spironolactone (SPIR) resulted in a substantial reduction in living cell numbers and migration, as evidenced by a scratch assay.

Both inhibitors led to a marked decrease in filament formation of F-actin, and the cellular localization of beta-catenin became more intracellular compared to control samples. Tumors derived from GBM treated with PBN exhibited a reduction in tumor cell viability via bioluminescent imaging and a decrease in hemorrhaging incidents.

These findings suggest that PANX1 could be a promising therapeutic target for GBM and could play a role in multiple cancer signaling pathways that govern this debilitating disease.