Browsing by Author "Ohtsuka, Masahisa"

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    H19 Noncoding RNA, an Independent Prognostic Factor, Regulates Essential Rb-E2F and CDK8-β-Catenin Signaling in Colorectal Cancer
    (Elsevier, 2016-11) Ohtsuka, Masahisa; Ling, Hui; Ivan, Cristina; Pichler, Martin; Matsushita, Daisuke; Goblirsch, Matthew; Stiegelbauer, Verena; Shigeyasu, Kunitoshi; Zhang, Xinna; Chen, Meng; Vidhu, Fnu; Bartholomeusz, Geoffrey A.; Toiyama, Yuji; Kusunoki, Masato; Doki, Yuichiro; Mori, Masaki; Song, Shumei; Gunther, Jillian R.; Krishnan, Sunil; Slaby, Ondrej; Goel, Ajay; Ajani, Jaffer A.; Radovich, Milan; Calin, George A.; Department of Surgery, IU School of Medicine
    The clinical significance of long noncoding RNAs (lncRNAs) in colorectal cancer (CRC) remains largely unexplored. Here, we analyzed a large panel of lncRNA candidates with The Cancer Genome Atlas (TCGA) CRC dataset, and identified H19 as the most significant lncRNA associated with CRC patient survival. We further validated such association in two independent CRC cohorts. H19 silencing blocked G1-S transition, reduced cell proliferation, and inhibited cell migration. We profiled gene expression changes to gain mechanism insight of H19 function. Transcriptome data analysis revealed not only previously identified mechanisms such as Let-7 regulation by H19, but also RB1-E2F1 function and β-catenin activity as essential upstream regulators mediating H19 function. Our experimental data showed that H19 affects phosphorylation of RB1 protein by regulating gene expression of CDK4 and CCND1. We further demonstrated that reduced CDK8 expression underlies changes of β-catenin activity, and identified that H19 interacts with macroH2A, an essential regulator of CDK8 gene transcription. However, the relevance of H19-macroH2A interaction in CDK8 regulation remains to be experimentally determined. We further explored the clinical relevance of above mechanisms in clinical samples, and showed that combined analysis of H19 with its targets improved prognostic value of H19 in CRC.
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    MicroRNAs: Clinical Relevance in Colorectal Cancer
    (MDPI, 2015) Thomas, Joe; Ohtsuka, Masahisa; Pichler, Martin; Ling, Hui
    Colorectal cancer is one of the most common cancer diagnoses and causes of mortality worldwide. MicroRNAs are a class of small, non-coding regulatory RNAs that have shown strong associations with colorectal cancer. Through the repression of target messenger RNAs, microRNAs modulate many cellular pathways, such as those involved in cell proliferation, apoptosis, and differentiation. The utilization of microRNAs has shown significant promise in the diagnosis and prognosis of colorectal cancer, owing to their unique expression profile associations with cancer types and malignancies. Moreover, microRNA therapeutics with mimics or antagonists show great promise in preclinical studies, which encourages further development of their clinical use for colorectal cancer patients. The unique ability of microRNAs to affect multiple downstream pathways represents a novel approach for cancer therapy. Although still early in its development, we believe that microRNAs can be used in the near future as biomarkers and therapeutic targets for colorectal cancer.