Abstract 373: An siRNA screen identifies CHD4 as a target for epigenetic therapy

In this study, we used an unbiased screen to investigate therapeutic targets which might be effective combination with DNMT inhibitors in reactivating hypermethylated genes. Methods: We screened an siRNA library targeting 188 gene predicted as epigenetic regulators using colon cancer cells that harbor a GFP locus stably integrated and silenced by a hypermethylated cytomegalovirus (CMV) promoter. GFP-positive cell percentages were measured using Guava EasyCyte Plus flow analyzer software. For genome wide gene expression analysis, affymetrix microarrays were performed. DNA methylation status was evaluated by pyrosequencing analysis and Digital Restriction Enzyme Analysis of Methylation (DREAM), based on next generation sequencing analysis. To access biological effect of the combination therapy, we evaluated cell growth using several cell lines. Results: We identified the chromodomain helicase DNA-binding protein 4 (CHD4) as a target; CHD4 depletion in combination with DNMT inhibition synergistically reactivated expression of GFP and endogenously methylated genes. Synergy was most pronounced for genes with very low basal expression. DREAM analysis revealed that methylated genes with promoter CpG islands were enriched among reactivated genes compared to background genes (57% vs 27%, P

Source: Cancer Research - September 30, 2014 Category: Cancer & Oncology Authors: Okamoto, Y., Yamazaki, J., Sato, T., Cesaroni, M., Chung, W., Garriga, J., Jelinek, J., Katz, R. A., Issa, J.-P. Tags: Molecular and Cellular Biology Source Type: research