Abstract A28: Identification of HDAC inhibitor potentiating targets in acute myeloid leukemia cells by large-scale RNA-interference

Abstract

Abstract The lysine deacetylase inhibitor suberoylanilide acid (SAHA) has shown promising but limited activity in the treatment of acute myeloid leukemia (AML). To identify potential targets for rational combination therapies that increase the efficacy of SAHA in AML, we used a functional RNA-interference (RNAi) screening approach to identify genes, that when inhibited, potentiate the in vitro anti-leukemic activity of SAHA. A total of 901 kinase, phosphatase and associated signaling genes were silenced, with four different siRNA sequences per gene, in combination with SAHA treatment. Log2 values of the ratio [(siRNA + SAHA)/(siRNA alone)] were calculated, with median and standard deviation determined on a per-plate basis. Hits were defined as ≥ 2 standard deviations from the log2 ratio median. Hit lists for each cell line were over-laid on an integrated functional relationship network. We applied a community detection algorithm to this sub-network and identified siRNA sensitive modules. Each module represents a highly connected set of genes in the integrated network. To identify the pathways represented by each module, we evaluated enrichment using the National Cancer Institute (NCI) Protein Interaction Database (PID) pathways. Several novel sensitizing targets, grouped into a small number of pathways, emerged from these screens. Some hits exhibit little to no anti-leukemic activity when silenced alone, indicative of synthetic lethal interaction with SAHA treatment. Initial validation experiments with siRNA and novel small molecule inhibitors confirm RNAi screen results and pharmacological sensitization is observed. The first reported large-scale HDAC inhibitor RNAi screen in leukemias has identified a novel rational combination that can be translated into design of a clinical trial. Citation Format: James M. Bogenberger, James E. Rudd, Donald Chow, Michelle Kassner, Holly Yin, Casey S. Greene, Raoul Tibes. Identification of HDAC inhibitor potentiating targets in acute myeloid leukemia cells by large-scale RNA-interference. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr A28.