GCLC Deficiency Enhances Cellular Uptake of BNCT Agents via Oxidative Stress-Induced Macropinocytosis

Abstract Boron neutron capture therapy (BNCT) is a promising targeted radiotherapy for osteosarcoma, offering selective tumor cytotoxicity and localized energy deposition, but its efficacy is limited by heterogeneous intratumoral boron distribution. Using a genome-wide CRISPR-Cas9 screen in U2OS osteosarcoma cells, we identified genetic regulators of boron uptake. GCLC deficiency markedly enhanced internalization of boron-containing agents. Mechanistically, GCLC loss depleted glutathione, triggered oxidative stress, and potentiated macropinocytosis, thereby boosting boron compound uptake. This effect was preferentially observed in tumor cells, as GCLC deficiency profoundly enhanced the uptake of boron delivery agents in tumor cells (such as U2OS and MDA-MB-231), far exceeding its impact on normal osteoblasts (HOB-SV40). In U2OS xenografts, GCLC silencing significantly enhanced preferential boron accumulation in tumors without altering normal tissue biodistribution. Our findings nominate GCLC as a druggable target to overcome boron delivery barriers in BNCT, providing a translatable strategy to improve efficacy for osteosarcoma, especially refractory cases.