title: The epigenetic regulation of Dicer and microRNA biogenesis by Panobinostat.
abstract: microRNAs (miRs) are small noncoding RNAs that regulate/fine tune many cellular protein networks by targeting mRNAs for either degradation or translational inhibition. Dicer, a type III endoribonuclease, is a critical component in miR biogenesis and is required for mature microRNA production. Abnormal Dicer expression occurs in numerous cancer types and correlates with poor patient prognosis. Recent reports have demonstrated that epigenetic agents, including histone deacetylase inhibitors (HDACi), may regulate Dicer and miR expression. HDACi are a class of epigenetic agents used to treat cancer, viral infections, and inflammatory disorders. However, little is known regarding the epigenetic regulation of miR biogenesis and function. We therefore investigated whether clinically successful HDACi modulated Dicer expression and found that Panobinostat, a clinically approved HDACi, enhanced Dicer expression via posttranscriptional mechanisms. Studies using proteasome inhibitors suggested that Panobinostat regulated the proteasomal degradation of Dicer. Further studies demonstrated that Panobinostat, despite increasing Dicer protein expression, decreased Dicer activity. This suggests that Dicer protein levels do not necessarily correlate with Dicer activity and mature miR levels. Taken together, we present evidence here that Panobinostat posttranscriptionally regulates Dicer/miR biogenesis and suggest Dicer as a potential therapeutic target in cancer.
authors.affiliation: a Laboratory of Molecular Medicine, Department of Immunology , Roswell Park Cancer Institute , Buffalo , NY , USA.
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Hoffend
authors.affiliation: a Laboratory of Molecular Medicine, Department of Immunology , Roswell Park Cancer Institute , Buffalo , NY , USA.|b Department of Microbiology & Immunology , School of Medicine and Biomedical Sciences, State University of New York , Buffalo , NY , USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Magner
authors.affiliation: a Laboratory of Molecular Medicine, Department of Immunology , Roswell Park Cancer Institute , Buffalo , NY , USA.|b Department of Microbiology & Immunology , School of Medicine and Biomedical Sciences, State University of New York , Buffalo , NY , USA.|c Department of Medicine , School of Medicine and Biomedical Sciences, State University of New York , Buffalo , NY , USA.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Tomasi
mesh_terms: D044127:Epigenesis, Genetic; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006367:HeLa Cells; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology*; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D000077767:Panobinostat; D043244:Ribonuclease III / Q000235:genetics* / Q000378:metabolism
chemical_list: D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D007211:Indoles; D035683:MicroRNAs; D000077767:Panobinostat; D043244:Ribonuclease III
keywords: Dicer; HDACi; Panobinostat; microRNA; posttranscriptional