Abstract 2026: KDM1A inhibition augment ER stress inducers efficacy to reduce glioblastoma stemness
Authors: He Yi , Venkata Prabhakar Pitta , Alejo Salvador , Chen Yihong , Palacios Bridgitte , Gray Gabrielle , Pratap Uday P. , Viswanadhapalli Suryavathi , Zheng Siyuan , Tekmal Rajeshwar R. , Brenner Andrew J. , Sareddy Gangadhara R. 
Published: July 2021

Background: Glioblastoma (GBM) is the most common malignant brain tumor with a dismal prognosis and median survival of 20 months. Standard therapy consists of surgical resection, external beam radiation therapy, adjuvant chemotherapy with temozolomide, and tumor-treating fields. Despite these therapies, GBM patients inevitably experience tumor progression and eventually succumb to their disease. Glioma stem cells (GSCs) play a central role in GBM development and contribute to treatment resistance. Recently we showed that lysine-specific histone demethylase 1A (KDM1A/LSD1) is essential for GSCs stemness, and inhibition of KDM1A induces unfolded protein response (UPR) in GSCs. In this study, we tested the hypothesis that inhibition of KDM1A sensitizes GSCs to ER stress inducers by inducing UPR.

Methods: KDM1A knockdown (KDM1A-KD) cells were generated using KDM1A specific shRNA. We studied the effect of KDM1A-KD or pharmacological KDM1A inhibitors (NCD38 and NCL-1) in combination with ER stress inducers (thapsigargin and brefeldin A) on GSCs viability using CellTiter-Glo assay. Stemness was determined using extreme limiting dilution analysis (ELDA) and sphere formation assays. Mechanistic studies were conducted using RNA-seq, ChIP, RT-qPCR, and Western blotting analysis. Furthermore, the in vivo efficacy of KDM1A inhibitor and ER stress inducer was studied using orthotopic models of GBM.

Results: Cell viability assays demonstrated that knockdown or inhibition of KDM1A sensitized GSCs to ER stress inducers thapsigargin and brefeldin A. Furthermore, KDM1A-KD, NCD38, or NCL-1, in combination with ER stress inducers, significantly decreased the stemness and sphere-forming ability of GSCs. RNA-seq analysis revealed that UPR was activated after knockdown or inhibition of KDM1A in GSCs. Western blot and RT-qPCR analysis showed that a combination of KDM1A inhibitors and ER stress inducers increased UPR signaling in GSCs. ChIP analysis indicated that KDM1A inhibition enriched the active histone methylation mark (H3K4me2) at the promoter of UPR target genes. In vivo studies showed that KDM1A inhibition activates UPR in tumors and improved overall survival.

Conclusions: Our results support that KDM1A knockdown or inhibition sensitizes GSCs to ER stress inducers and that the use of KDM1A inhibitors in conjunction with ER stress inducers is a potential novel therapy for GBM patients.

Citation Format: Yi He, Prabhakar Pitta Venkata, Salvador Alejo, Yihong Chen, Bridgitte Palacios, Gabrielle Gray, Uday P. Pratap, Suryavathi Viswanadhapalli, Siyuan Zheng, Rajeshwar R. Tekmal, Andrew J. Brenner, Gangadhara R. Sareddy. KDM1A inhibition augment ER stress inducers efficacy to reduce glioblastoma stemness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2026.