Abstract 3510: Novel lysine demethylase LSD1 inhibitors promote differentiation and apoptosis of glioma stem cells

Abstract

Abstract Glioblastoma (GBM) is the most common and devastating primary tumor of the central nervous system with dismal prognosis. GBM development is a multistep process, involving alterations in genetic and epigenetic mechanisms. Understanding the mechanisms and enzymes that promote epigenetic changes in GBM are urgently needed to identify novel therapeutic targets. Recent studies demonstrated that Glioma Stem Cells (GSCs) play central roles in GBM development and responsible for tumor propagation, invasion and chemo/radiation resistance. GSCs elimination is critical for development of efficient therapeutic strategies for GBM. Recently, we showed that lysine demethylase LSD1 is overexpressed in GBM and its inhibition reduces proliferation of GBM cells. In this study, we tested whether, LSD1 modulates GSCs differentiation and novel LSD1 inhibitors (NCL-1 and NCD-38) promote differentiation and apoptosis of GSCs. We have isolated GSCs using well established stem markers (CD133 and CD15) from two established and two patient derived GBM cells. Functionality of GSCs was established using self-renewal assays, and by profiling stem cell marker expression. Western analysis of purified GSCs showed that LSD1 is highly expressed in purified GSCs. Differentiation of GSCs resulted in decreased expression of LSD1. Down regulation of LSD1 expression using lentiviral LSD1-shRNA or by pharmacological inhibition (NCL-1 and NCD-38) significantly reduced the proliferation, neurosphere formation and self-renewal ability of GSCs with little or no effect on normal astrocytes and differentiated cells. Accordingly, treatment of GSCs with LSD1 inhibitors resulted in a dramatic reduction in the expression of stemness markers and promoted induction of differentiation markers. RNA sequencing analysis of GSCs treated with or without LSD1 inhibitors, revealed that LSD1 inhibitors modulate several pathways related to stem ness, differentiation and apoptosis. The expression of top five genes and three pathways were validated using q-RT-PCR, and western blot analysis. Chromatin Immunoprecipitation assays confirmed significant alternations in epigenetic markers at LSD1 target genes. Further, LSD1 inhibitors significantly reduced the growth of GSC driven tumors in vivo. Taken together, these results provided the evidence that induction of GSCs differentiation and apoptosis following LSD1 inhibition as a promising approach to eradicate GSCs. Citation Format: Gangadhara R. Sareddy, Takayoshi Suzuki, Andrew J. Brenner, Ratna K. Vadlamdui. Novel lysine demethylase LSD1 inhibitors promote differentiation and apoptosis of glioma stem cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3510. doi:10.1158/1538-7445.AM2015-3510