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
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- Published online on: June 1, 2010 https://doi.org/10.3892/ijo_00000637
- Pages: 1503-1512
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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-α signaling pathway was the most significant pathway modulated by differentially expressed genes. STAT1 and STAT2 are core proteins in the IFN-α 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-α signaling after knockdown of miR-221/222 cluster in U251 glioma cells.