title: Combinatorial pharmacologic approaches target EZH2-mediated gene repression in breast cancer cells.
abstract: Polycomb protein EZH2-mediated gene silencing is implicated in breast tumorigenesis through methylation of histone H3 on Lysine 27 (H3K27). We have previously shown that S-adenosylhomocysteine hydrolase inhibitor 3-deazaneplanocin A can modulate histone methylation and disrupt EZH2 complex. Here, we used 3-deazaneplanocin A, together with other chromatin remodeling agents, as well as RNA interference-mediated EZH2 depletion, to probe the role of EZH2 in coordination with other epigenetic components in gene regulation in breast cancer cells. Through genome-wide gene expression analysis, coupled with extensive chromatin immunoprecipitation analysis of histone modifications, we have identified a variety of gene sets that are regulated either by EZH2 alone or through the coordinated action of EZH2 with HDAC and/or DNA methylation. We further found that tumor antigen GAGEs were regulated by distinct epigenetic mechanisms in a cell context-dependent manner, possibly reflecting mechanistic heterogeneity in breast cancer. Intriguingly, we found that EZH2 regulates a remarkable cohort of genes whose functions are highly enriched in immunoresponse and autocrine inflammation network, and that their transcriptional activation upon EZH2 perturbation is cancer specific, revealing a potential novel role of EZH2 in regulating cancer immunity. These findings show the complexity and diversity of epigenetic regulation in human cancer and underscore the importance for developing combinatorial pharmacologic approaches for effective epigenetic gene reactivation.
authors.affiliation: Cancer Biology and Pharmacology, Genome Institute of Singapore, 60 Biopolis Street, #02-01 Genome, Singapore 138672.
authors.forename: Feng
authors.initials: F
authors.lastname: Sun
authors.forename: Eli
authors.initials: E
authors.lastname: Chan
authors.forename: Zhenlong
authors.initials: Z
authors.lastname: Wu
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Yang
authors.forename: Victor E
authors.initials: VE
authors.lastname: Marquez
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yu
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D016000:Cluster Analysis; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D000077209:Decitabine; D000071221:Enhancer of Zeste Homolog 2 Protein; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids; D015151:Immunoblotting; D008745:Methylation / Q000187:drug effects; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D063151:Polycomb Repressive Complex 2; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; C095366:GAGE2A protein, human; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D009363:Neoplasm Proteins; D014157:Transcription Factors; C012589:trichostatin A; C048460:3-deazaneplanocin; D000077209:Decitabine; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D000241:Adenosine; D001374:Azacitidine