title: Interdependent regulation of p53 and miR-34a in chronic lymphocytic leukemia.
abstract: Chronic lymphocytic leukemia (CLL) has an incidence 4/1,00,000 people in the western world and is one of the first cancers reported to be associated with deregulated miRNA expression. microRNAs are small non coding RNAs that are important regulators of protein expression through binding to their untranslated 3'-UTR region. The miR-34 family was demonstrated to be induced by the tumor suppressor p53 and to elicit p53-like responses like senescence, cell cycle arrest and apoptosis depending on the cell type. We have shown in a recent paper that miR-34a is severely increased in the TCL1-mouse model of CLL. This finding was reflected in human CLL. Moreover, it is demonstrated that its expression is dependent on the presence of the SNP309 in the intronic promoter of the MDM2 gene. In addition, low miR-34a expression was associated with shorter time to treatment (log-rank p = 0.003) in CLL. When reintroduced into CLL cells, miR-34a was able to induce apoptosis. Interestingly, this was dependent on an intact p53 pathway. Here, we present data showing that knockdown of p53 in HCT-116 cells severely reduces miR-34a induced apoptosis. In conclusion, miR-34a is proposed as a marker for the activity of the p53 pathway in CLL.
authors.affiliation: Laboratory for Immunological and Molecular Cancer Research, IIIrd Medical Department with Hematology, Medical Oncology, Hemostaseology, Rheumatology and Infectiology of the Paracelsus Medical University Salzburg, Salzburg, Austria. o.merkel@salk.at
authors.forename: Olaf
authors.initials: O
authors.lastname: Merkel
authors.forename: Daniela
authors.initials: D
authors.lastname: Asslaber
authors.forename: Josefina D
authors.initials: JD
authors.lastname: Piñón
authors.forename: Alexander
authors.initials: A
authors.lastname: Egle
authors.forename: Richard
authors.initials: R
authors.lastname: Greil
mesh_terms: D017209:Apoptosis; D045325:HCT116 Cells; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism*; D035683:MicroRNAs / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: C522425:MIRN34 microRNA, human; D035683:MicroRNAs; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2