title: Reversible LSD1 inhibition interferes with global EWS/ETS transcriptional activity and impedes Ewing sarcoma tumor growth.
abstract: OBJECTIVE
  Ewing sarcoma is a pediatric bone tumor that absolutely relies on the transcriptional activity of the EWS/ETS family of fusion oncoproteins. While the most common fusion, EWS/FLI, utilizes lysine-specific demethylase 1 (LSD1) to repress critical tumor suppressors, small-molecule blockade of LSD1 has not yet been thoroughly explored as a therapeutic approach for Ewing sarcoma. We therefore evaluated the translational potential of potent and specific LSD1 inhibition with HCI2509 on the transcriptional program of both EWS/FLI and EWS/ERG as well as the downstream oncogenic phenotypes driven by EWS/ETS fusions in both in vitro and in vivo models of Ewing sarcoma.
  
  
  METHODS
  RNA-seq was used to compare the transcriptional profiles of EWS/FLI, EWS/ERG, and treatment with HCI2509 in both EWS/FLI- and EWS/ERG-containing cell lines. We then evaluated morphologic phenotypes of treated cells with immunofluorescence. The induction of apoptosis was evaluated using caspase-3/7 activation and TUNEL staining. Colony forming assays were used to test oncogenic transformation and xenograft studies with patient-derived cell lines were used to evaluate the effects of HCI2509 on tumorigenesis.
  
  
  RESULTS
  HCI2509 caused a dramatic reversal of both the up- and downregulated transcriptional profiles of EWS/FLI and EWS/ERG accompanied by the induction of apoptosis and disruption of morphologic and oncogenic phenotypes modulated by EWS/FLI. Importantly, HCI2509 displayed single-agent efficacy in multiple xenograft models.
  
  
  CONCLUSIONS
  These data support epigenetic modulation with HCI2509 as a therapeutic strategy for Ewing sarcoma, and highlight a critical dual role for LSD1 in the oncogenic transcriptional activity of EWS/ETS proteins.
authors: Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, Utah.
authors: Savita
authors: S
authors: Sankar
authors: Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah. Department of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, University of Utah, Salt Lake City, Utah.
authors: Emily R
authors: ER
authors: Theisen
authors: Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
authors: Jared
authors: J
authors: Bearss
authors: University of Utah School of Medicine, Salt Lake City, Utah.
authors: Timothy
authors: T
authors: Mulvihill
authors: Department of Biology, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
authors: Laura M
authors: LM
authors: Hoffman
authors: Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
authors: Venkataswamy
authors: V
authors: Sorna
authors: Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, Utah. Department of Biology, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
authors: Mary C
authors: MC
authors: Beckerle
authors: Center for Investigational Therapeutics at Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah. Division of Medical Oncology, University of Utah School of Medicine, Salt Lake City, Utah.
authors: Sunil
authors: S
authors: Sharma
authors: Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, Utah. Center for Children's Cancer Research at Huntsman Cancer Institute, Salt Lake City, Utah. Division of Pediatric Hematology/Oncology, University of Utah School of Medicine, Salt Lake City, Utah. stephen.lessnick@hci.utah.edu.
authors: Stephen L
authors: SL
authors: Lessnick
mesh_terms: D017209:Apoptosis / Q000235:genetics; D001859:Bone Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D044127:Epigenesis, Genetic; D015972:Gene Expression Regulation, Neoplastic; D056466:Histone Demethylases / Q000037:antagonists & inhibitors / Q000235:genetics*; D006801:Humans; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D050784:Proto-Oncogene Protein c-ets-1 / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics; D034802:RNA-Binding Protein EWS / Q000235:genetics*; D012512:Sarcoma, Ewing / Q000235:genetics* / Q000473:pathology; D015534:Trans-Activators / Q000235:genetics; D000071230:Transcriptional Regulator ERG
chemical_list: C072312:ERG protein, human; D015514:Oncogene Proteins, Fusion; D050784:Proto-Oncogene Protein c-ets-1; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D056466:Histone Demethylases; C495195:KDM1A protein, human