Reversible LSD1 inhibition interferes with global EWS/ETS transcriptional activity and impedes Ewing sarcoma tumor growth

Clin Cancer Res. 2014 Sep 1;20(17):4584-97. doi: 10.1158/1078-0432.CCR-14-0072. Epub 2014 Jun 24.

Abstract

Purpose: 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.

Experimental design: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / genetics
  • Bone Neoplasms / genetics*
  • Bone Neoplasms / pathology
  • Cell Line, Tumor
  • Cell Proliferation
  • Cell Transformation, Neoplastic / genetics
  • Epigenesis, Genetic
  • Gene Expression Regulation, Neoplastic
  • Histone Demethylases / antagonists & inhibitors
  • Histone Demethylases / genetics*
  • Humans
  • Oncogene Proteins, Fusion / genetics*
  • Proto-Oncogene Protein c-ets-1 / genetics*
  • Proto-Oncogene Protein c-fli-1 / genetics
  • RNA-Binding Protein EWS / genetics*
  • Sarcoma, Ewing / genetics*
  • Sarcoma, Ewing / pathology
  • Trans-Activators / genetics
  • Transcriptional Regulator ERG

Substances

  • ERG protein, human
  • Oncogene Proteins, Fusion
  • Proto-Oncogene Protein c-ets-1
  • Proto-Oncogene Protein c-fli-1
  • RNA-Binding Protein EWS
  • Trans-Activators
  • Transcriptional Regulator ERG
  • Histone Demethylases
  • KDM1A protein, human