Abstract LB-187: Identification of CIT-0665, a novel inhibitor of LSD1

Abstract

Abstract Lysine-specific demethylase 1 (LSD1/AOF2/KDM1A) is a flavin-dependent histone demethylase that catalyzes the posttranslational oxidative demethylation of mono- and dimethylated lysines on histones. Methylation of lysine residues on histones can signal transcriptional activation or repression depending on the specific residue involved. H3K4me2 is a transcription-activating chromatin mark at gene promoters, and demethylation of this mark by LSD1 is thought to prevent expression of tumor suppressor genes important in human cancer. In contrast, methylation of H3K9 is a repressive mark and LSD1 activity has been shown to upregulate tumor promoting pathways. Thus, LSD1 is emerging as an important target for the development of specific inhibitors as a new class of antitumor drugs. Currently, only a few existing compounds, such as monoamine oxidase inhibitors, have been shown to act as inhibitors of LSD1. More potent and specific inhibitors of LSD1 are needed to advance LSD1 biology and test for potential efficacy in tumor models. We utilized the 3-D crystal structure of LSD1 to computationally dock more than 10 million virtual compounds into the active site of the protein. From the docking experiments, we physically screened 52 compounds in an LSD1 biochemical assay (resorufin-based assay measuring the amount of hydrogen peroxide generated by LSD1). The compound CIT-0665 was identified as a potent inhibitor of LSD1 enzymatic activity, with an IC50 of 290nM. Additionally, cell lines treated with CIT-0665 show increased levels of H3K4 methylation. A large panel of cancer cell lines was also tested for sensitivity to CIT-0665, using a cell viability assay. We are currently engaged in determining possible mechanisms of sensitivity from the cell line panel and making analogs of CIT-0665 with improved drug-like qualities. In conclusion, CIT-0665 is a novel LSD-1 inhibitor with activity in biochemical and cell-based assays. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-187. doi:10.1158/1538-7445.AM2011-LB-187