Abstract Diffuse midline glioma (DMG) is a highly invasive and fatal pediatric brain tumor originating in the pons of the brainstem. Despite focal radiation therapy, DMG has a poor prognosis, with a median survival of less than 10 months. A significant challenge in treating DMG is the blood-brain barrier (BBB), which restricts therapeutic agents from reaching the brain at effective concentrations. Previous studies from the Lawler lab showed that the indirubin derivative 6-bromoindirubin-3′-acetoxime(BIO-acetoxime/BIA) has anti-invasive properties and enhances survival in glioblastoma xenograft models. We investigated BIA’s effects in pediatric glioma models using various assays. In an in vitro scratch migration assay, BIA at 1 µM significantly slowed cell migration in pediatric glioma cells over 72 hours. Additionally, BIA was shown to modulate tumor vasculature and improve drug delivery to tumors by targeting tight junctions in tumor-associated endothelium. BIA treatment increased dextran uptake into 3D BBB models and lowered endothelial cell permeability in vitro by reducing the expression of tight junction proteins, as shown by staining and a decrease in TEER values. Furthermore, BIA’s anti-angiogenic effects were demonstrated through staining, showing significant alterations in angiogenesis-related protein expression. To explore potential synergistic therapies, a drug screen was performed on a panel of pediatric glioma cell lines which identified several FDA-approved drugs that pair well with BIA. Among these, Vorinostat, an HDAC inhibitor, showed promise, significantly enhancing cell killing in SU-DIPG 36 cells. Time-course analysis revealed that BIA modulates signaling pathways, with reduced AKT expression and dynamic changes in ERK phosphorylation in both KNS42 and endothelial cells. These findings suggest BIA impacts key tumor and vascular pathways. Our hypothesis is that BIA could be an effective therapeutic agent for DMG by targeting tumor invasion, angiogenesis, and improving drug delivery. Future studies will focus on elucidating the underlying mechanisms and developing drug formulations for in vivo studies to assess the translational potential of this approach
Clark et al. (2025) studied this question.