Therapeutic targeting of KDM1A/LSD1 in Ewing sarcoma engages the ER-stress response I

The purpose of this study was to define biomarkers of sensitivty and mechanisms of resistance to the KDM1A/LSD1 inhibtor SP-2509 (HCI-2509) in Ewing sarcoma cell lines. We report that regardless of drug sensitivity all cell lines engage the UPR and ER-stress response following treatment with SP-2509 resulting in apoptotic cytotoxicity. In addition hypersentsitive cell lines shared a common basal transcriptnomic profile, with hypersensitive cell lines signficantly inducing ETS1 which was not observed in sensitive cell lines. Overall design: 6 Ewing sarcoma cell lines were treated with either vehicle control (DMSO) or the reversible LSD1/KDM1A inhibitor SP-2509 (2uM) for 48hrs. Three SP-2509 hypersensitive (IC50< 300nM)(A673, TC32, TC252) and three SP-2509 sensitive (IC50>900nM) (EWS-502, ES-2 and TC71) cell lines were investigated. Paired RNA from three indpendent experiments per cell line was analyzed.