EXTH-104. Dual Targeting of KDM1A/LSD1 and Endoplasmic Reticulum Stress Pathways as a Therapeutic Strategy in Glioblastoma

BACKGROUND Glioblastoma is the lethal primary brain tumor, with glioblastoma stem cells (GSCs) playing a critical role in tumor heterogeneity, drug resistance, and recurrence. Understanding the mechanisms underlying glioblastoma stemness and identifying therapeutic agents to suppress it may improve patient survival. In this study, we investigated the critical role of histone demethylase KDM1A/LSD1 in modulating endoplasmic reticulum (ER) stress and evaluated its therapeutic potential in combination with ER stress-inducing agents. METHODS The combinatorial effects of KDM1A knockdown or pharmacological inhibition with NCD38, together with ER stress inducers thapsigargin and brefeldin A, were assessed using cell viability, neurosphere formation, extreme limiting dilution, and apoptosis assays. Mechanistic studies were conducted using CUT&Tag-seq for KDM1A, H3K4me2, H3K4me3, and H3K27Ac, as well as RNA-seq, transmission electron microscopy, ChIP, Western blotting, and qPCR. The in vivo efficacy of combined NCD38 and thapsigargin treatment was tested in orthotopic GSC models. RESULTS KDM1A knockdown or inhibition induced ER stress in patient-derived GSCs and enhanced the efficacy of ER stress inducers by reducing GSC viability and stemness and promoting apoptosis. CUT&Tag-seq analysis revealed that KDM1A is enriched near the transcription start sites (TSS) of unfolded protein response (UPR) pathway genes and its inhibition increased the enrichment of active histone mark H3K4me2 and acetylation mark H3K27Ac at UPR gene promoters, thereby upregulating their expression. Notably, KDM1A inhibition reduced the expression of the sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2/ATP2A2) by increasing the repressive histone mark H3K9me2 at its promoter. Knockdown of ATP2A2 synergized with KDM1A inhibition to further suppress GSC viability and stemness. Furthermore, combined treatment with a KDM1A inhibitor and ER stress inducer significantly improved survival in tumor-bearing mice. CONCLUSIONS Our findings demonstrate that KDM1A inhibition induces ER stress in GSCs and targeting KDM1A in combination with ER stress induction represents a promising therapeutic strategy for glioblastoma.