title: miR-30e controls DNA damage-induced stress responses by modulating expression of the CDK inhibitor p21WAF1/CIP1 and caspase-3.
abstract: MicroRNAs (miRNAs), a class of small non-coding RNAs that usually cause gene silencing by translational repression or degradation of mRNAs, are implicated in DNA damage-induced stress responses. To identify senescence-associated miRNAs, we performed microarray analyses using wild-type and p53-deficient HCT116 colon carcinoma cells that following gamma-irradiation (γIR) are driven into senescence and apoptosis, respectively. Several miRNAs including miR-30e were found upregulated in a p53-dependent manner specifically in senescent cells, but not in apoptotic cells. Overexpression of miR-30e in HCT116 cells not only inhibited γIR-, etoposide- or miR-34a-induced caspase-3-like DEVDase activities and cell death, but greatly accelerated and augmented their senescent phenotype. Consistently, procaspase-3 protein, but not mRNA decreased in the presence of miR-30e, whereas expression of the cyclin-dependent kinase inhibitor p21 increased both at the mRNA and protein level. Performing luciferase reporter gene assays, we identified the 3'-UTR of the caspase-3 mRNA as a direct miR-30e target. In contrast, although miR-30e was unable to bind to the p21 mRNA, it increased expression of a luciferase construct containing the p21 promoter, suggesting that the miR-30e-mediated upregulation of p21 occurs indirectly at the transcriptional level. Interestingly, despite suppressing procaspase-3 expression, miR-30e was unable to protect RKO colon carcinoma cells from DNA damage-induced death or to induce senescence, as miR-30e completely fails to upregulate p21 in these cells. These data suggest that miR-30e functions in a cell type-dependent manner as an important molecular switch for DNA damage-induced stress responses and may thus represent a target of therapeutic value.
authors.affiliation: Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty of The Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Dennis
authors.initials: D
authors.lastname: Sohn
authors.affiliation: Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty of The Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Peters
authors.affiliation: Institute for Biochemistry and Molecular Biology II, Medical Faculty of The Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Roland P
authors.initials: RP
authors.lastname: Piekorz
authors.affiliation: Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty of The Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Wilfried
authors.initials: W
authors.lastname: Budach
authors.affiliation: Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty of The Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Reiner U
authors.initials: RU
authors.lastname: Jänicke
mesh_terms: D053148:Caspase 3 / Q000096:biosynthesis*; D016922:Cellular Senescence / Q000502:physiology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis*; D004249:DNA Damage / Q000502:physiology*; D005786:Gene Expression Regulation; D045325:HCT116 Cells; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C546086:MIRN30b microRNA, human; D035683:MicroRNAs; C505407:CASP3 protein, human; D053148:Caspase 3
keywords: apoptosis; caspase-3; microRNA-30e; p21; senescence