Screening for Tumor Microtube-Targeting Drugs Identifies PKC Modulators as Multipotent Inhibitors of Glioblastoma Progression

Glioblastomas are incurable primary brain tumors that depend on neural-like cellular processes, tumor microtubes (TMs), to invade the brain. TMs also interconnect single tumor cells to a communicating multicellular network that resists current therapies. Here, we developed a combined, comprehensive in vitro/in vivo anti-TM drug screening approach, including machine-learning-based analysis tools. Two Protein Kinase C (PKC) modulators robustly inhibited TM formation and pacemaker tumor cell-driven, TM-mediated glioblastoma cell network communication. Since TM-unconnected tumor cells exhibited increased sensitivity to cytotoxic therapy, the PKC activator TPPB was combined with radiotherapy, and long-term intravital 2-photon microscopy paired with spatially resolved multiomics revealed anti-TM and anti-tumor effects. TPPB treatment also decreased the expression of tweety family member 1 (TTYH1), a key driver of invasive TMs. Our study establishes a novel screening pipeline for anti-TM drug development, identifies a TM master regulator pathway, and supports the approach of TM targeting for efficient brain tumor therapies.