title: miR-221 overexpression contributes to liver tumorigenesis.
abstract: MicroRNA (miRNAs) are negative regulators of gene expression and can function as tumor suppressors or oncogenes. Expression patterns of miRNAs and their role in the pathogenesis of hepatocellular carcinoma (HCC) are still poorly understood. We profiled miRNA expression in tissue samples (104 HCC, 90 adjacent cirrhotic livers, 21 normal livers) as well as in 35 HCC cell lines. A set of 12 miRNAs (including miR-21, miR-221/222, miR-34a, miR-519a, miR-93, miR-96, and let-7c) was linked to disease progression from normal liver through cirrhosis to full-blown HCC. miR-221/222, the most up-regulated miRNAs in tumor samples, are shown to target the CDK inhibitor p27 and to enhance cell growth in vitro. Conversely, these activities can be efficiently inhibited by an antagomiR specific for miR-221. In addition, we show, using a mouse model of liver cancer, that miR-221 overexpression stimulates growth of tumorigenic murine hepatic progenitor cells. Finally, we identified DNA damage-inducible transcript 4 (DDIT4), a modulator of mTOR pathway, as a bona fide target of miR-221. Taken together, these data reveal an important contribution for miR-221 in hepatocarcinogenesis and suggest a role for DDIT4 dysregulation in this process. Thus, the use of synthetic inhibitors of miR-221 may prove to be a promising approach to liver cancer treatment.
authors.affiliation: Nuclear Organization and Oncogenesis Unit, Institut National de Santé et de Recherche Médicale U579, Institut Pasteur, 75724 Paris Cedex 15, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Pineau
authors.forename: Stefano
authors.initials: S
authors.lastname: Volinia
authors.forename: Katherine
authors.initials: K
authors.lastname: McJunkin
authors.forename: Agnès
authors.initials: A
authors.lastname: Marchio
authors.forename: Carlo
authors.initials: C
authors.lastname: Battiston
authors.forename: Benoît
authors.initials: B
authors.lastname: Terris
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Mazzaferro
authors.forename: Scott W
authors.initials: SW
authors.lastname: Lowe
authors.forename: Carlo M
authors.initials: CM
authors.lastname: Croce
authors.forename: Anne
authors.initials: A
authors.lastname: Dejean
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism; D003937:Diagnosis, Differential; D005355:Fibrosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008099:Liver / Q000473:pathology / Q000502:physiology; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D046228:Microarray Analysis; D015203:Reproducibility of Results; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D050760:Cyclin-Dependent Kinase Inhibitor p27; D035683:MicroRNAs; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; C469991:DDIT4 protein, human; C525709:MIR221, human