title: miR-17-92 cluster promotes cholangiocarcinoma growth: evidence for PTEN as downstream target and IL-6/Stat3 as upstream activator.
abstract: miR-17-92 is an oncogenic miRNA cluster implicated in the development of several cancers; however, it remains unknown whether the miR-17-92 cluster is able to regulate cholangiocarcinogenesis. This study was designed to investigate the biological functions and molecular mechanisms of the miR-17-92 cluster in cholangiocarcinoma. In situ hybridization and quantitative RT-PCR analysis showed that the miR-17-92 cluster is highly expressed in human cholangiocarcinoma cells compared with the nonneoplastic biliary epithelial cells. Forced overexpression of the miR-17-92 cluster or its members, miR-92a and miR-19a, in cultured human cholangiocarcinoma cells enhanced tumor cell proliferation, colony formation, and invasiveness, in vitro. Overexpression of the miR-17-92 cluster or miR-92a also enhanced cholangiocarcinoma growth in vivo in hairless outbred mice with severe combined immunodeficiency (SHO-Prkdc(scid)Hr(hr)). The tumor-suppressor, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), was identified as a bona fide target of both miR-92a and miR-19a in cholangiocarcinoma cells via sequence prediction, 3' untranslated region luciferase activity assay, and Western blot analysis. Accordingly, overexpression of the PTEN open reading frame protein (devoid of 3' untranslated region) prevented miR-92a- or miR-19a-induced cholangiocarcinoma cell growth. Microarray analysis revealed additional targets of the miR-17-92 cluster in human cholangiocarcinoma cells, including APAF-1 and PRDM2. Moreover, we observed that the expression of the miR-17-92 cluster is regulated by IL-6/Stat3, a key oncogenic signaling pathway pivotal in cholangiocarcinogenesis. Taken together, our findings disclose a novel IL-6/Stat3-miR-17-92 cluster-PTEN signaling axis that is crucial for cholangiocarcinogenesis and tumor progression.
authors.affiliation: Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Hanqing
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Chang
authors.initials: C
authors.lastname: Han
authors.affiliation: Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Lu
authors.affiliation: Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana. Electronic address: twu@tulane.edu.
authors.forename: Tong
authors.initials: T
authors.lastname: Wu
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D001650:Bile Duct Neoplasms / Q000473:pathology*; D001653:Bile Ducts, Intrahepatic / Q000473:pathology; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000473:pathology*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D064593:Heterografts; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D008297:Male; D051379:Mice; D016513:Mice, SCID; D035683:MicroRNAs / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D051059:PTEN Phosphohydrolase / Q000235:genetics*; D062085:RNA, Long Noncoding; D050796:STAT3 Transcription Factor / Q000235:genetics*; D015398:Signal Transduction; D059467:Transcriptome
chemical_list: D020413:3' Untranslated Regions; C508600:IL6 protein, human; D015850:Interleukin-6; C568997:MIR17HG, human; D035683:MicroRNAs; D062085:RNA, Long Noncoding; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human