title: The tumor-suppressive miR-497-195 cluster targets multiple cell-cycle regulators in hepatocellular carcinoma.
abstract: MicroRNAs (miRNAs) are key post-transcriptional regulators of gene expression and commonly deregulated in carcinogenesis. To explore functionally crucial tumor-suppressive (TS)-miRNAs in hepatocellular carcinoma (HCC), we performed integrative function- and expression-based screenings of TS-miRNAs in six HCC cell lines. The screenings identified seven miRNAs, which showed growth-suppressive activities through the overexpression of each miRNA and were endogenously downregulated in HCC cell lines. Further expression analyses using a large panel of HCC cell lines and primary tumors demonstrated four miRNAs, miR-101, -195, -378 and -497, as candidate TS-miRNAs frequently silenced in HCCs. Among them, two clustered miRNAs miR-195 and miR-497 showed significant growth-suppressive activity with induction of G1 arrest. Comprehensive exploration of their targets using Argonute2-immunoprecipitation-deep-sequencing (Ago2-IP-seq) and genome-wide expression profiling after their overexpression followed by pathway analysis, revealed a significant enrichment of cell cycle regulators. Among the candidates, we successfully identified CCNE1, CDC25A, CCND3, CDK4, and BTRC as direct targets for miR-497 and miR-195. Moreover, target genes frequently upregulated in HCC in a tumor-specific manner, such as CDK6, CCNE1, CDC25A and CDK4, showed an inverse correlation in the expression of miR-195 and miR-497, and their targets. These results suggest the molecular pathway regulating cell cycle progression to be integrally altered by downregulation of miR-195 and miR-497 expression, leading to the aberrant cell proliferation in hepatocarcinogenesis.
authors.affiliation: Department of Molecular Cytogenetics, Medical Research Institute and School of Biomedical Science, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Mayuko
authors.initials: M
authors.lastname: Furuta
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Kozaki
authors.forename: Kousuke
authors.initials: K
authors.lastname: Tanimoto
authors.forename: Shinji
authors.initials: S
authors.lastname: Tanaka
authors.forename: Shigeki
authors.initials: S
authors.lastname: Arii
authors.forename: Teppei
authors.initials: T
authors.lastname: Shimamura
authors.forename: Atsushi
authors.initials: A
authors.lastname: Niida
authors.forename: Satoru
authors.initials: S
authors.lastname: Miyano
authors.forename: Johji
authors.initials: J
authors.lastname: Inazawa
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology; D002453:Cell Cycle / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019295:Computational Biology; D003198:Computer Simulation; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D058977:Molecular Sequence Annotation; D005810:Multigene Family; D015203:Reproducibility of Results
chemical_list: C552722:MIRN195 microRNA, human; C559640:MIRN497 microRNA, human; D035683:MicroRNAs
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