title: Genome structure-based screening identified epigenetically silenced microRNA associated with invasiveness in non-small-cell lung cancer.
abstract: MicroRNA (miRNA) expression is frequently altered in human cancers. To search for epigenetically silenced miRNAs in non-small-cell lung cancer (NSCLC), we mapped human miRNAs on autosomal chromosomes and selected 55 miRNAs in silico. We treated six NSCLC cell lines with the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-aza-CdR) and determined the expressions of the 55 miRNAs. Fourteen miRNAs were decreased in the cancer cell lines and were induced after 5-aza-CdR treatment. After a detailed DNA methylation analysis, we found that mir-34b and mir-126 were silenced by DNA methylation. Mir-34b was silenced by the DNA methylation of its own promoter, whereas mir-126 was silenced by the DNA methylation of its host gene, EGFL7. A chromatin immunoprecipitation assay revealed H3K9me2 and H3K9me3 in mir-34b and EGFL7, and H3K27me3 in EGFL7. The overexpression of mir-34b and mir-126 decreased the expression of c-Met and Crk, respectively. The 5-aza-CdR treatment of lung cancer cell line resulted in increased mir-34b expression and decreased c-Met protein. We next analyzed the DNA methylation status of these miRNAs using 99 primary NSCLCs. Mir-34b and mir-126 were methylated in 41 and 7% of all the cases, respectively. The DNA methylation of mir-34b was not associated with c-Met expression determined by immunohistochemistry, but both mir-34b methylation (p = 0.007) and c-Met expression (p = 0.005) were significantly associated with lymphatic invasion in a multivariate analysis. The DNA methylation of mir-34b can be used as a biomarker for an invasive phenotype of lung cancer.
authors.affiliation: Department of Respiratory Medicine, The University of Tokyo Hospital, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kousuke
authors.initials: K
authors.lastname: Watanabe
authors.forename: Noriko
authors.initials: N
authors.lastname: Emoto
authors.forename: Emi
authors.initials: E
authors.lastname: Hamano
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Sunohara
authors.forename: Masanori
authors.initials: M
authors.lastname: Kawakami
authors.forename: Hidenori
authors.initials: H
authors.lastname: Kage
authors.forename: Kentaro
authors.initials: K
authors.lastname: Kitano
authors.forename: Jun
authors.initials: J
authors.lastname: Nakajima
authors.forename: Akiteru
authors.initials: A
authors.lastname: Goto
authors.forename: Masashi
authors.initials: M
authors.lastname: Fukayama
authors.forename: Takahide
authors.initials: T
authors.lastname: Nagase
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yatomi
authors.forename: Nobuya
authors.initials: N
authors.lastname: Ohishi
authors.forename: Daiya
authors.initials: D
authors.lastname: Takai
mesh_terms: D000328:Adult; D000368:Aged; D002135:Calcium-Binding Proteins; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology; D047369:Chromatin Immunoprecipitation; D019175:DNA Methylation; D066255:EGF Family of Proteins; D016228:Endothelial Growth Factors / Q000235:genetics; D044127:Epigenesis, Genetic; D005260:Female; D020868:Gene Silencing; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D008297:Male; D035683:MicroRNAs / Q000502:physiology*; D008875:Middle Aged; D009361:Neoplasm Invasiveness
chemical_list: D002135:Calcium-Binding Proteins; D066255:EGF Family of Proteins; C527877:EGFL7 protein, human; D016228:Endothelial Growth Factors; D035683:MicroRNAs