title: p53 represses c-Myc through induction of the tumor suppressor miR-145.
abstract: The tumor suppressor p53 negatively regulates a number of genes, including the proto-oncogene c-Myc, in addition to activating many other genes. One mechanism of the p53-mediated c-Myc repression may involve transcriptional regulation. However, it is not clear whether microRNAs (miRNAs) play a role in the p53-mediated posttranscriptional regulation of c-Myc. In this study, we show that a putative tumor suppressor, miR-145, is expressed through the phosphoinositide-3 kinase (PI-3K)/Akt and p53 pathways. Importantly, p53 transcriptionally induces the expression of miR-145 by interacting with a potential p53 response element (p53RE) in the miR-145 promoter. We further show that c-Myc is a direct target for miR-145. Although miR-145 silences the expression of c-Myc, anti-miR-145 enhances its expression. This specific silencing of c-Myc by miR-145 accounts at least in part for the miR-145-mediated inhibition of tumor cell growth both in vitro and in vivo. Finally, the blockade of miR-145 by anti-miR-145 is able to reverse the p53-mediated c-Myc repression. Together, these results define the role of miR-145 in the posttranscriptional regulation of c-Myc by p53 and suggest that, as a new member of the p53 regulatory network, miR-145 provides a direct link between p53 and c-Myc in this gene regulatory network.
authors.affiliation: Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL 62794, USA.
authors.forename: Mohit
authors.initials: M
authors.lastname: Sachdeva
authors.forename: Shoumin
authors.initials: S
authors.lastname: Zhu
authors.forename: Fangting
authors.initials: F
authors.lastname: Wu
authors.forename: Hailong
authors.initials: H
authors.lastname: Wu
authors.forename: Vijay
authors.initials: V
authors.lastname: Walia
authors.forename: Sumit
authors.initials: S
authors.lastname: Kumar
authors.forename: Randolph
authors.initials: R
authors.lastname: Elble
authors.forename: Kounosuke
authors.initials: K
authors.lastname: Watabe
authors.forename: Yin-Yuan
authors.initials: YY
authors.lastname: Mo
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005786:Gene Expression Regulation; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000090063:Proto-Oncogene Mas; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: C000715470:MAS1 protein, human; D035683:MicroRNAs; D000090063:Proto-Oncogene Mas; D016271:Proto-Oncogene Proteins c-myc; D016159:Tumor Suppressor Protein p53; D051057:Proto-Oncogene Proteins c-akt