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Transcription profiling by array of HCC cells with RNAi knock-down of YAP

ABSTRACT: siRNA-mediated inhibition compared to untreated cells and cells transfected with nonsense siRNA. Loss of contact inhibition and anchorage-independent growth are hallmarks of cancer cells. In this context, frequent inactivation of the Hippo pathway and subsequent nuclear enrichment of the transcriptional coactivator yes-associated protein (YAP) uncouple cell proliferation and anti-apoptosis from contact inhibition, associated with uncontrolled tumor growth and tumor cell dissemination. However, general molecular mechanisms of tumor-supporting YAP activity remain unclear. In this study, we show that overexpression and nuclear accumulation of YAP in hepatocytes and hepatocellular carcinoma (HCC) cells leads to an induction of the Notch pathways through transcriptional activation of the Notch ligand jagged-1 (Jag-1). This induction of Jag-1 strictly depends on binding of YAP to TEAD4 and does not rely on WNT/β-catenin pathway activity. Co-activation of YAP, TEAD4, Jag-1, and the Notch target gene Hes-1 was significantly higher in HCC from patients with poor prognosis. High-level expression and nuclear accumulation of YAP correlates with Jag-1/Notch activation not only in human HCC tissues, but also in colon and pancreatic cancer tissues. Thus, our data demonstrate that YAP-driven co-activation of the Jag-1/Notch pathway in part facilitates oncogenic properties of the oncogene YAP not only in HCC but also in different gastrointestinal malignancies. Expression profiling of untreated HCC cell lines (control 1), cells transfected with scrambled/nonsense siRNA (control 2), and after siRNA-mediated YAP inhibition.

ORGANISM(S): Homo sapiens

SUBMITTER: Sticht Carsten

PROVIDER: S-ECPF-GEOD-35004 | biostudies-other |

REPOSITORIES: biostudies-other

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Project description:"Bmi-1 and Mel-18 are close structural homologues that belong to the polycomb group (PcG) of transcriptional regulators of homeotic gene expression in development. They are believed to stably maintain repression of gene expression by altering the state of chromatin at specific promoters. A number of clinical and experimental observations have also implicated Bmi-1 in tumorigenesis and stem cell maintenance. Bmi-1 overexpression or amplification has been observed in a number of human malignancies, particularly in B-cell lymphomas, medulloblastomas and breast cancer. We report here that shRNA-mediated knock-down of either Bmi-1 or Mel-18 in human medulloblastoma DAOY cells results in the inhibition of proliferation, loss of clonogenic survival and anchorage-independent growth, and suppression of xenograft tumor formation in nude mice. Furthermore, overexpression of both Bmi-1 and Mel-18 significantly increased clonogenic survival of Rat1 fibroblasts. In contrast, stable downregulation of Bmi-1 or Mel-18 alone did not affect the growth of SK-OV-3 or U2OS cancer cell lines or normal human WI38 fibroblasts. Gene expression analysis of shRNA-expressing DAOY cells has demonstrated a significant overlap in the Bmi-1- and Mel-18-regulated genes and revealed novel gene targets under their control. Taken together, these results suggest that Bmi-1 and Mel-18 might have overlapping functions in human tumorigenesis. Experiment Overall Design: DAOY cells were transduced with the indicated lentiviral shRNA and stable cell lines were generated by selection in puromycin (1 µg/ml). 2 x 105 cells of each stable cell line were plated onto 60 mm dishes in triplicates and harvested 4 days later. Triplicate total RNA samples from shRNA-expressing and mock-transduced DAOY cells were isolated using affinity resin (Qiagen RNeasy Mini Kit, Qiagen AG). RNA Integrity and purity were assessed with the RNA 6000 Nano LabChip system on Bioanalyzer 2100 (Agilent Technologies). Gene array analysis was conducted at the Genomics Factory at Novartis PHARMA AG, Basel, Switzerland using Gene Chip Human Genome 133 2.0 Plus Expression Array (Affymetrix Inc.)."

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Transcription profiling by array of HCC cells with RNAi knock-down of YAP

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