title: Overexpression of miR-214-3p in esophageal squamous cancer cells enhances sensitivity to cisplatin by targeting survivin directly and indirectly through CUG-BP1.
abstract: Based on its marked overexpression in multiple malignancies and its roles in promoting cell survival and proliferation, survivin is an attractive candidate for targeted therapy. Toward this end, a detailed understanding of the mechanisms regulating survivin expression in different cancer cells will be critical. We have previously shown that the RNA-binding protein (RBP) CUG-BP1 is overexpressed in esophageal cancer cells and post-transcriptionally regulates survivin in these cells. The objective of this study was to investigate the role of microRNAs (miRs) in regulating survivin expression in esophageal cancer cells. Using miR expression profiling analysis, we found that miR-214-3p is one of the most markedly downregulated miRs in two esophageal squamous cancer cell lines compared with esophageal epithelial cells. Interestingly, using miR target prediction programs, both survivin and CUG-BP1 mRNA were found to contain potential binding sites for miR-214-3p. Forced expression of miR-214-3p in esophageal cancer cells leads to a decrease in the mRNA and protein levels of both survivin and CUG-BP1. This effect is due to decreased mRNA stability of both targets. By contrast, silencing miR-214-3p in esophageal epithelial cells leads to an increase in both survivin and CUG-BP1 mRNA and protein. To determine whether the observed effect of miR-214-3p on survivin expression was direct, mediated through CUG-BP1, or both, binding studies utilizing biotin pull-down assays and heterologous luciferase reporter constructs were performed. These demonstrated that the mRNA of survivin and CUG-BP1 each contain two functional miR-214-3p-binding sites as confirmed by mutational analysis. Finally, forced expression of miR-214-3p enhances the sensitivity of esophageal cancer cells to cisplatin-induced apoptosis. This effect is abrogated with rescue expression of survivin or CUG-BP1. These findings suggest that miR-214-3p acts as a tumor suppressor and that its downregulation contributes to chemoresistance in esophageal cancer cells by targeting both survivin and CUG-BP1.
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: P
authors.initials: P
authors.lastname: Phatak
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Byrnes
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: D
authors.initials: D
authors.lastname: Mansour
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: S
authors.initials: S
authors.lastname: Cao
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: R
authors.initials: R
authors.lastname: Li
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: J N
authors.initials: JN
authors.lastname: Rao
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Turner
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.|Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: J-Y
authors.initials: JY
authors.lastname: Wang
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.|Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Donahue
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000067879:CELF1 Protein / Q000502:physiology*; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000473:pathology; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000502:physiology*; D035683:MicroRNAs / Q000235:genetics*; D000077022:Survivin
chemical_list: D000970:Antineoplastic Agents; C107489:BIRC5 protein, human; D000067879:CELF1 Protein; C102843:CELF1 protein, human; D051034:Inhibitor of Apoptosis Proteins; C547397:MIRN214 microRNA, human; D035683:MicroRNAs; D000077022:Survivin; D002945:Cisplatin