title: Epigenetic therapy with 3-deazaneplanocin A, an inhibitor of the histone methyltransferase EZH2, inhibits growth of non-small cell lung cancer cells.
abstract: EZH2 (enhancer of zeste homolog 2) is the catalytic subunit of PRC2 (polycomb repressive complex 2), which mediates histone methyltransferase activity and functions as transcriptional repressor involved in gene silencing. EZH2 is involved in malignant transformation and biological aggressiveness of several human malignancies. We previously demonstrated that non-small cell lung cancers (NSCLCs) also overexpress EZH2 and that high expression of EZH2 correlates with poor prognosis. Growing evidence indicates that EZH2 may be an appropriate therapeutic target in malignancies, including NSCLCs. Recently, an S-adenosyl-l-homocysteine hydrolase inhibitor, 3-Deazaneplanocin A (DZNep), has been shown to deplete and inhibit EZH2. The aim of this study was to determine the effect of DZNep in NSCLC cells. Knockdown of EZH2 by small-interfering RNA (siRNA) resulted in decreased growth of four NSCLC cell lines. MTT assays demonstrated that DZNep treatment resulted in dose-dependent inhibition of proliferation in the NSCLC cell lines with a half maximal inhibitory concentration (IC50) ranging from 0.08 to 0.24 μM. Immortalized but non-cancerous bronchial epithelial and fibroblast cell lines were less sensitive to DZNep than the NSCLC cell lines. Soft agarose assays demonstrated that anchorage-independent growth was also reduced in all three NSCLC cell lines that were evaluated using this assay. Flow cytometry analysis demonstrated that DZNep induced apoptosis and G1 cell cycle arrest in NSCLC cells, which was partially associated with cyclin A decrease and p27(Kip1) accumulation. DZNep depleted cellular levels of EZH2 and inhibited the associated histone H3 lysine 27 trimethylation. These results indicated that an epigenetic therapy that pharmacologically targets EZH2 via DZNep may constitute a novel approach to treatment of NSCLCs.
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Kikuchi
authors.forename: Taichi
authors.initials: T
authors.lastname: Takashina
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kinoshita
authors.forename: Eiki
authors.initials: E
authors.lastname: Kikuchi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Jun
authors.initials: J
authors.lastname: Sakakibara-Konishi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Oizumi
authors.forename: Victor E
authors.initials: VE
authors.lastname: Marquez
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nishimura
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Dosaka-Akita
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000235:genetics; D045744:Cell Line, Tumor / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D000071221:Enhancer of Zeste Homolog 2 Protein; D044127:Epigenesis, Genetic / Q000187:drug effects; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D006657:Histones / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics; D008745:Methylation; D009363:Neoplasm Proteins; D063151:Polycomb Repressive Complex 2 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D034622:RNA Interference; D014157:Transcription Factors
chemical_list: D000970:Antineoplastic Agents; C491488:EED protein, human; D006657:Histones; D009363:Neoplasm Proteins; C430461:SUZ12 protein, human; D014157:Transcription Factors; D050760:Cyclin-Dependent Kinase Inhibitor p27; C048460:3-deazaneplanocin; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D000241:Adenosine