title: Global changes of mRNA expression reveals an increased activity of the interferon-induced signal transducer and activator of transcription (STAT) pathway by repression of miR-221/222 in glioblastoma U251 cells.
abstract: MicroRNA (miR)-221 and miR-222 are frequently upregulated in various types of human malignancy including glioblastoma. Previous studies have identified some targets of miR-221 and miR-222, such as p27 and p57. Inter-relationship between miR-221 and miR-222 expression and global mRNA expression remains elusive. Here we knocked down miR-221 and miR-222 expression and found 158 differentially expressed genes with 2-fold changes in U251 glioma cells by microarray analysis. Using the KEGG pathway databases and BioCarta, we found that the IFN-alpha signaling pathway was the most significant pathway modulated by differentially expressed genes. STAT1 and STAT2 are core proteins in the IFN-alpha signaling pathway. By Western blotting and immunofluorescence, we found that STAT1 and STAT2 expression and phosphorylation were upregulated in U251 cells with knocked-down miR-221/222. Furthermore, tyrosine phosphorylation of STAT1 and STAT2 was present in the nucleus after repression of miR-221/222 expression in U251 cells. These data indicate for the first time a mechanism involving STAT1/2 upregulation under the transcriptional control of INF-alpha signaling after knockdown of miR-221/222 cluster in U251 glioma cells.
authors.affiliation: Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China.
authors.forename: Chunzhi
authors.initials: C
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Han
authors.forename: Anling
authors.initials: A
authors.lastname: Zhang
authors.forename: Weidong
authors.initials: W
authors.lastname: Yang
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhou
authors.forename: Peiyu
authors.initials: P
authors.lastname: Pu
authors.forename: Yue
authors.initials: Y
authors.lastname: Du
authors.forename: Huazong
authors.initials: H
authors.lastname: Zeng
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Kang
mesh_terms: D015153:Blotting, Western; D045744:Cell Line, Tumor; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D005909:Glioblastoma / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D016898:Interferon-alpha / Q000378:metabolism; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D050791:STAT Transcription Factors / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D016898:Interferon-alpha; D035683:MicroRNAs; D012333:RNA, Messenger; D050791:STAT Transcription Factors; C525709:MIR221, human; C525710:MIR222, human