Secreted CD44-Fc oHSV Is Associated with One-Carbon Metabolic Changes and AKT/MAPK Shifts in Glioblastoma

Glioblastoma (GBM) remains one of the deadliest primary brain tumors due to its aggressive nature, adaptability, and resistance to standard therapies. This study explores the mechanism by which an engineered oncolytic herpes simplex virus (oHSV-CD44)—expressing a secreted CD44-Fc decoy that modulates CD44-ligand interactions in the tumor microenvironment; viral entry receptors are unchanged and the construct does not retarget entry to CD44 cells—affects one-carbon metabolism and its subsequent impact on AKT and MAPK signaling pathways in glioblastoma stem cells (GSCs). Applying proteomics and experimental data from in vitro assays, we elucidate how metabolic disruptions in one-carbon metabolism interplay with key survival pathways to impair GSC maintenance. Our results indicate that the downregulation of enzymes involved in one-carbon metabolism, specifically MTHFD1 and SHMT2, leads to impaired redox balance and nucleotide synthesis, which in turn modulates AKT and MAPK signaling dynamics, altering GSC proliferation and survival. These findings highlight the interconnected nature of metabolic and signaling pathways in GSCs and present a novel perspective on targeting GBM metabolism alongside signaling for effective therapy.