DDEL-14 - Exploring the role of Wnt pathway inhibition on glioma stem cells progression and brain endothelial integrity

The blood–brain barrier (BBB) is a specialized neurovascular unit evolved to maintain brain homeostasis and prevent effective agents from reaching malignant brain tumors such as glioblastoma. The Wnt/β-catenin signaling pathway helps to ensure BBB integrity and previous studies demonstrate Wnt pathway inhibition increases BBB permeability. High grade gliomas express increased Wnt expression compared with normal tissue. We hypothesize that Wnt pathway inhibition in glioma stem cells (GSCs) will hinder progression, increase BBB permeability, and enhance overall treatment response. In this study, we transduced primary pediatric-derived glioma stem cells with lentiviral vectors overexpressing Wnt inhibitors (DKK1 or WIF1) and then characterized migration, proliferation, and cell cycle progression. WNT inhibition on brain endothelial cell integrity was evaluated with GSC conditioned media (GSC-CM) +/- CHIR99021 (Wnt pathway activator) for function via electrical cell-cell impedance and junctional expression. Wnt inhibitor overexpression was verified using RNAseq, proteomic analysis, and immunoblotting. We found that GSC-DKK1 demonstrated significantly decreased cell migration (p < 0.005) and proliferation (p < 0.0001). We also found that CHIR99021 treated GSC-CM endothelial cells displayed decreased tight junctional proteins and increased fenestration protein expression (p < 0.0005), correlating with a more porous endothelium. Overall, our studies showed Wnt inhibitor overexpressing GSCs impaired glioma progression in vitro and indirectly disrupted endothelial cell integrity. Future studies will evaluate orthotopic Wnt inhibitor overexpressing transplant rodent models to assess changes in BBB integrity, drug permeability, model survival, and treatment response. Further understanding of the Wnt pathway in both GSCs and the BBB has the potential for improved central nervous system treatment penetration and prolonged disease response.