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Browsing by Subject "DEAD-box RNA Helicases"
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Item Global microRNA expression is essential for murine mast cell development in vivo(Elsevier, 2014-10) Oh, Sun Young; Brandal, Stephanie; Kapur, Reuben; Zhu, Zhou; Takemoto, Clifford; Department of Pediatrics, IU School of MedicineMicroRNAs (miRNAs) are small, noncoding RNAs that have been shown to play a critical role in normal physiology and disease, such as hematopoietic development and cancer. However, their role in mast-cell function and development is poorly understood. The major objective of this study was to determine how global miRNA expression affects mast-cell physiology. The RNase III endonuclease, Dicer, is required for the processing of pre-miRNAs into mature miRNAs. To investigate the effect of global miRNA depletion on mast cells in vivo, we generated a mast-cell-specific knock out of Dicer in mice. Transgenic mice (Mcpt5-Cre) that express Cre selectively in connective tissue mast cells were crossed with mice carrying the floxed conditional Dicer allele (Dicer fl/fl). Mcpt5-Cre × Dicer fl/fl mice with homozygous Dicer gene deletion in mast cells were found to have a profound mast-cell deficiency with near complete loss of peritoneal, gastrointestinal, and skin mast cells. We examined the in vivo functional consequence of mast-cell-specific Dicer deletion using an immunoglobulin-E-dependent passive systemic anaphylaxis murine model. Immunoglobulin-E-sensitized wild type Mcpt5-Cre × Dicer +/+ and heterozygous Mcpt5-Cre × Dicer fl/+ mice show marked hypothermia with antigen; however, homozygous Mcpt5-Cre × Dicer fl/fl mice were completely unresponsive to antigen challenge. These studies suggest a critical role for Dicer and miRNA expression for establishment of tissue compartments of functional mast cells in vivoItem Hypoxia promotes stem cell phenotypes and poor prognosis through epigenetic regulation of DICER(Nature Publishing Group, 2014-10-29) van den Beucken, Twan; Koch, Elizabeth; Chu, Kenneth; Rupaimoole, Rajesha; Prickaerts, Peggy; Adriaens, Michiel; Voncken, Jan Willem; Harris, Adrian L.; Buffa, Francesca M.; Haider, Syed; Starmans, Maud H. W.; Yao, Cindy Q.; Ivan, Mircea; Ivan, Cristina; Pecot, Chad V.; Boutros, Paul C.; Sood, Anil K.; Koritzinsky, Marianne; Wouters, Bradly G.; Department of Medicine, IU School of MedicineMicroRNAs are small regulatory RNAs that post-transcriptionally control gene expression. Reduced expression of DICER, the enzyme involved in microRNA processing, is frequently observed in cancer and is associated with poor clinical outcome in various malignancies. Yet the underlying mechanisms are not well understood. Here, we identify tumor hypoxia as a regulator of DICER expression in large cohorts of breast cancer patients. We show that DICER expression is suppressed by hypoxia through an epigenetic mechanism that involves inhibition of oxygen-dependent H3K27me3 demethylases KDM6A/B and results in silencing of the DICER promoter. Subsequently, reduced miRNA processing leads to derepression of the miR-200 target ZEB1, stimulates the epithelial to mesenchymal transition and ultimately results in the acquisition of stem cell phenotypes in human mammary epithelial cells. Our study uncovers a previously unknown relationship between oxygen-sensitive epigenetic regulators, miRNA biogenesis and tumor stem cell phenotypes that may underlie poor outcome in breast cancer.Item Targeting 17q23 amplicon to overcome the resistance to anti-HER2 therapy in HER2+ breast cancer(Nature Research, 2018-11-09) Liu, Yunhua; Xu, Jiangsheng; Choi, Hyun Ho; Han, Cecil; Fang, Yuanzhang; Li, Yujing; Van der Jeught, Kevin; Xu, Hanchen; Zhang, Lu; Frieden, Michael; Wang, Lifei; Eyvani, Haniyeh; Sun, Yifan; Zhao, Gang; Zhang, Yuntian; Liu, Sheng; Wan, Jun; Huang, Cheng; Ji, Guang; Lu, Xiongbin; He, Xiaoming; Zhang, Xinna; Medical and Molecular Genetics, School of MedicineChromosome 17q23 amplification occurs in ~11% of human breast cancers. Enriched in HER2+ breast cancers, the 17q23 amplification is significantly correlated with poor clinical outcomes. In addition to the previously identified oncogene WIP1, we uncover an oncogenic microRNA gene, MIR21, in a majority of the WIP1-containing 17q23 amplicons. The 17q23 amplification results in aberrant expression of WIP1 and miR-21, which not only promotes breast tumorigenesis, but also leads to resistance to anti-HER2 therapies. Inhibiting WIP1 and miR-21 selectively inhibits the proliferation, survival and tumorigenic potential of the HER2+ breast cancer cells harboring 17q23 amplification. To overcome the resistance of trastuzumab-based therapies in vivo, we develop pH-sensitive nanoparticles for specific co-delivery of the WIP1 and miR-21 inhibitors into HER2+ breast tumors, leading to a profound reduction of tumor growth. These results demonstrate the great potential of the combined treatment of WIP1 and miR-21 inhibitors for the trastuzumab-resistant HER2+ breast cancers.