Time-Dependent Modulation of ISR and UPR in Glioblastoma Stem Cells Using a Curcumin-Inspired Bis-Chalcone Analog

Time-Dependent Modulation of ISR and UPR in Glioblastoma Stem Cells Using a Curcumin-Inspired Bis-Chalcone Analog

Alvin Sherman Library

Glioblastoma (GBM) is an aggressive brain tumor driven by therapy-resistant GBM stem cells (GSCs). GSC's rely on adaptive stress pathways like the Integrated Stress Response (ISR) and Unfolded Protein Response (UPR). Curcumin modulates these pathways but has poor bioavailability. We developed curcumin-inspired bis-clacone analogs with improved potency and selectivity against GSCs and tested efficiency using a time-course study. A series of bis-chalcone analogs were synthesized and tested against three patient-derived GSC lines using MTS assay (0.1-10 μM, 72 h). A lead derivative compound compatible with carbon dot nanoparticle conjugation was synthesized and evaluated for mechanistic consistency and GSC cytotoxicity. ISR/UPR modulation and apoptosis were analyzed by Western blot with a time-course study assessing these pathways at 2, 4, 6, 8,12, and 24 hours after treatment. The lead bis-chalcone analog showed potent GSC cytotoxicity (IC50 = 270 nM), approximately 100-fold stronger than curcumin (25 μM), with minimal toxicity to non-tumor cells. Mechanistic studies revealed ISR activation (increased phosphorylated eIF2α and robust ATF4 and CHOP expression) and UPR suppression (reduced ATF6 and no FRP78 induction). The carbon dot-compatible analog reproduced these effects and maintained selective GSC cytotoxicity. Through iterative synthesis, we developed a curcumin-inspired, bis-chalcone analog with stellar GSC cytotoxicity (IC50 = 270 nM) and minimal non-tumor toxicity, optimized to eliminate therapy-resistant GSCs. Mechanistic insights uncovered ISR activation and UPR suppression. The carbon dot-ready derivative retains this activity, providing a promising platform for advanced GBM therapies targeting resistant GSCs.