title: Identification of microprocessor-dependent cancer cells allows screening for growth-sustaining micro-RNAs.
abstract: Micro-RNAs are deregulated in cancer cells, and some are either tumor suppressive or oncogenic. In addition, a link has been established between decreased expression of micro-RNAs and transformation, and several proteins of the RNA interference pathway have been shown to be haploinsufficient tumor suppressors. Oncogenic micro-RNAs (oncomiRs) could represent new therapeutic targets, and their identification is therefore crucial. However, structural and functional redundancy between micro-RNAs hampers approaches relying on individual micro-RNA inhibition. We reasoned that in cancer cells that depend on oncomiRs, impairing the micro-RNA pathway could lead to growth perturbation rather than increased tumorigenesis. Identifying such cells could allow functional analyses of individual micro-RNAs by complementation of the phenotypes observed upon global micro-RNA inhibition. Therefore, we developed episomal vectors coding for small hairpin RNAs targeting either Drosha or DGCR8, the two components of the microprocessor, the nuclear micro-RNA maturation complex. We identified cancer cell lines in which both vectors induced colony growth arrest. We then screened for individual micro-RNAs complementing this growth arrest, and identified miR-19a, miR-19b, miR-20a and miR-27b as major growth-sustaining micro-RNAs. However, the effect of miR-19a and miR-19b was only transient. In addition, embryonic stem cell-derived micro-RNAs with miR-20a seeds were much less efficient than miR-20a in sustaining cancer cell growth, a finding that contrasted with results obtained in stem cells. Finally, we showed that the tumor suppressor phosphatase and tensin homologue deleted on chromosome 10, a shared target of miR-19 and miR-20, was functionally involved in the growth arrest induced by microprocessor inhibition. We conclude that our approach allowed to identify microprocessor-dependent cancer cells, which could be used to screen for growth-sustaining micro-RNAs. This complementation screen unveiled functional differences between homologous micro-RNAs. Phenotypic characterization of the complemented cells will allow precise functional studies of these micro-RNAs.
authors: CEA, DSV, iRCM, Laboratoire de Génétique de la Radiosensibilité (LGR), Fontenay aux Roses, France.
authors: D
authors: D
authors: Peric
authors: K
authors: K
authors: Chvalova
authors: G
authors: G
authors: Rousselet
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism*; D009369:Neoplasms / Q000235:genetics* / Q000473:pathology; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D016601:RNA-Binding Proteins; D043244:Ribonuclease III / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C474043:DGCR8 protein, human; C549214:MIRN19A microRNA, human; C534451:MIRN20a microRNA, human; D035683:MicroRNAs; D011506:Proteins; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C517918:DROSHA protein, human; D043244:Ribonuclease III; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human