Revealing the Roles of the SH3GLB1-Hydrogen Peroxide Axis in Glioblastoma Multiforme Cells

Glioblastoma (GBM) is a prevalent malignant brain tumor prone to drug resistance. We previously found a strong correlation between SH3 domain GRB2-like endophilin B1 (SH3GLB1) and superoxide dismutase 2 (SOD2), which converts O₂ to hydrogen peroxide (H₂O₂). Prior studies show that H₂O₂ redox signaling is vital for physiological processes and can drive tumor progression. Therefore, we aim to define how H₂O₂ signaling regulates SH3GLB1 and AKT (protein kinase B) pathways in GBM and to assess whether modulating H₂O₂ reverses temozolomide (TMZ) resistance.

We used cultured cells and pharmacological inhibitors and activators to confirm the significance of H₂O₂ signaling. GBM cells were used to verify the role of H₂O₂ signaling in cell state transitions and animal experiments identified optimal treatment strategies.

We found that SOD2 acts as an upstream regulator of SH3GLB1. When SOD inhibitors and TMZ were combined, cells showed reduced SH3GLB1 and autophagy levels. SH3GLB1 was found to be regulated by H₂O₂ via AKT signaling using redox homeostasis-regulating experiments. Although treatment-induced changes in mitochondrial H₂O₂ levels mirrored those in the cytosol, parental and resistant cells exhibited divergent fates, highlighting cell-fate plasticity. TMZ combined with a redox modulator reduced resistant tumor cell growth (about 2/3 reduction of tumor size; p < 0.05) and suppressed SH3GLB1 and autophagy levels in animal models. The TMZ-induced increase in SH3GLB1 expression was reversed by HgCl₂, which inhibited the aquaporin-9/AKT signaling.

Overall, these findings underscore the importance of H₂O₂-SH3GLB1 signaling in GBM and may inform future therapeutic strategies for overcoming TMZ resistance.