title: miR-25 targets TNF-related apoptosis inducing ligand (TRAIL) death receptor-4 and promotes apoptosis resistance in cholangiocarcinoma.
abstract: It has been established that microRNA expression and function contribute to phenotypic features of malignant cells, including resistance to apoptosis. Although targets and functional roles for a number of microRNAs have been described in cholangiocarcinoma, many additional microRNAs dysregulated in this tumor have not been assigned functional roles. In this study, we identify elevated miR-25 expression in malignant cholangiocarcinoma cell lines as well as patient samples. In cultured cells, treatment with the Smoothened inhibitor, cyclopamine, reduced miR-25 expression, suggesting Hedgehog signaling stimulates miR-25 production. Functionally, miR-25 was shown to protect cells against TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. Correspondingly, antagonism of miR-25 in culture sensitized cells to apoptotic death. Computational analysis identified the TRAIL Death Receptor-4 (DR4) as a potential novel miR-25 target, and this prediction was confirmed by immunoblot, cell staining, and reporter assays.
  
  
  CONCLUSIONS
  These data implicate elevated miR-25 levels in the control of tumor cell apoptosis in cholangiocarcinoma. The identification of the novel miR-25 target DR4 provides a mechanism by which miR-25 contributes to evasion of TRAIL-induced cholangiocarcinoma apoptosis.
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Razumilava
authors.forename: Steve F
authors.initials: SF
authors.lastname: Bronk
authors.forename: Rory L
authors.initials: RL
authors.lastname: Smoot
authors.forename: Christian D
authors.initials: CD
authors.lastname: Fingas
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Werneburg
authors.forename: Lewis R
authors.initials: LR
authors.lastname: Roberts
authors.forename: Justin L
authors.initials: JL
authors.lastname: Mott
mesh_terms: D020413:3' Untranslated Regions; D017209:Apoptosis; D001650:Bile Duct Neoplasms / Q000378:metabolism*; D001653:Bile Ducts, Intrahepatic / Q000473:pathology*; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000378:metabolism*; D005786:Gene Expression Regulation; D053823:Hedgehog Proteins / Q000378:metabolism; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D020413:3' Untranslated Regions; D053823:Hedgehog Proteins; C542541:MIRN106 microRNA, human; C543351:MIRN25 microRNA, human; D035683:MicroRNAs; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human