Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Deciphering the Wnt-dependent gene signature in colorectal cancer cells

ABSTRACT: Microarray-based gene expression data were generated from RNA from Ls174T colorectal carcinoma cell lines in which Wnt-dependent transcriptional activity can be abrogated by inducible overexpression of a dominant-negative form of Tcf4 or siRNA against M-NM-2-catenin. shRNA against M-NM-2-catenin, or a dominant-negative Tcf4 transgene, were induced in Ls174T cells for 72 or 24 hours, respectively. Uninduced cells were used as a control. Three replicates per condition.

ORGANISM(S): Homo sapiens

SUBMITTER: Rogier Versteeg

PROVIDER: E-GEOD-18560 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Integrated genome-wide analysis of transcription factor occupancy, RNA polymerase II binding and steady-state RNA levels identify differentially regulated functional gene classes.

Mokry Michal M Hatzis Pantelis P Schuijers Jurian J Lansu Nico N Ruzius Frans-Paul FP Clevers Hans H Cuppen Edwin E

Nucleic acids research 20110913 1

Routine methods for assaying steady-state mRNA levels such as RNA-seq and micro-arrays are commonly used as readouts to study the role of transcription factors (TFs) in gene expression regulation. However, cellular RNA levels do not solely depend on activity of TFs and subsequent transcription by RNA polymerase II (Pol II), but are also affected by RNA turnover rate. Here, we demonstrate that integrated analysis of genome-wide TF occupancy, Pol II binding and steady-state RNA levels provide impo ...[more]

PMID: 21914722

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Project description:Background: Wnt signaling maintains the undifferentiated state of intestinal crypt progenitor cells by inducing the formation of nuclear TCF4/beta-catenin complexes. In colorectal cancer, activating mutations in Wnt pathway components cause inappropriate activation of TCF4/beta-catenin -driven transcription. Despite the passage of a decade after the discovery of TCF4 and beta-catenin as the molecular effectors of the Wnt signal, few transcriptional activators essential and unique to the regulation of this transcription program have been found. Methodology/Principal Findings: Using proteomics, we identified the leukemia-associated Mllt10/Af10 and the methyltransferase Dot1l, as Tcf4/beta-catenin interactors in mouse small intestinal crypts. Mllt10/Af10-Dot1l, essential for transcription elongation, are recruited to Wnt target genes in a beta-catenin -dependent manner, resulting in H3K79 methylation over their coding regions in vivo in proliferative crypts of mouse small intestine, in colorectal cancer and Wnt-inducible HEK293T cells. Depletion of MLLT10/AF10 in colorectal cancer and Wnt-inducible HEK293T cells followed by expression array analysis identifies MLLT10/AF10 and DOT1L as essential activators dedicated to Wnt target gene regulation. In contrast, previously published b-catenin coactivators p300 and beta-catenin displayed a more pleiotropic target gene expression profile controlling Wnt and other pathways. tcf4, mllt10/af10 and dot1l are co-expressed in Wnt-driven tissues in zebrafish and essential for Wnt-reporter activity. Intestinal differentiation defects in apc-mutant zebrafish can be rescued by depletion of Mllt10 and Dot1l, establishing these genes as activators downstream of Apc in Wnt target gene activation in vivo. Morpholino-depletion of mllt10/af10-dot1l in zebrafish results in defects in intestinal homeostasis and a significant reduction in the in vivo expression of direct Wnt target genes and in the number of proliferative intestinal epithelial cells. Conclusions/Significance: We conclude that Mllt10/Af10-Dot1l are essential, dedicated activators of Wnt-dependent transcription, critical for maintenance of intestinal proliferation and homeostasis. The methyltransferase Dot1l may present an attractive candidate for drug targeting in colorectal cancer. 6 samples for Ls174T cells: si-b-catenin against si-control and dyeswap of it, si-control, si-MLLT10, si-BRG1 and si-P300 are hybridized against common reference RNA; 6 samples of HEK293T cells: Wnt3A or control medium (CM) induction for 9 hours, si-MLLT10, si-DOT1L, si-BRG1 and si-P300 upon 9 hour Wnt3A induction are all hybridized against common reference RNA

Project description:Most available CRC cell lines have lost their TGF-beta response through the acquisition of mutations either in TGF-beta type II receptor (TGFBR2) or the intracellular mediator SMAD4 (Reviewed in Markowitz et al. 2002). To study the effect of TGF-beta in CRC epithelial cells, we restored wild-type TGFBR2 expression in the CRC cell line LS174T (LS). Ls174T cells are mutant for beta-catenin and therefore exhibit constitutive Wnt activity, which results in the expression of a genetic profile similar to that of intestinal epithelial progenitor cells (van de Wetering, Sancho et al. 2002). They thus reflect tumor cells at the initial stages of tumorogenesis. In addition, Ls174T cells bear mutations in the TGF-beta receptor II (TGFBR2) sequence at the BATRII locus (Grady and Markowitz 2002). This mutation gives rise to a non-functional truncated form of the receptor lacking the transmembrane domain and the serine-threonine kinase domain (Parsons, Myeroff et al. 1995). We generated inducible clones of Ls174T cells, where the expression of TGFBR2 could be controlled at will by the presence or absence of doxycycline (LSTGFBR2 cell line). Re-expression of wild-type receptor in Ls174T cells (LSTGFBR2) restored TGF-beta signalling resulting in strong phosphorylation of SMADs and activation of SMAD-binding reporter activity. Functionally, TGF-beta signalling in LSTGFBR2 resulted in a strong cytostatic response. By genome wide expression profiling using microarrays we investigated genes regulated by TGF-beta in this cell line. LsTGFBR2 inducible cells were generated by the Invitrogen T-Rex system following manufacturers instructions. LSTGFBR2 were seeded at 60% confluence in the presence or absence of Doxycycline and treated with TGF-M-NM-21 for 16 hours. Gene expression profiles were measured in duplicate using HG-U133 plus 2.0. We used RMA background correction, quantile normalization and RMA summarization (Gautier et al., 2004). A TGF-M-NM-2 response signature was obtained by selecting genes with limma P-value < 0.05 and at least two fold up-regulation in TGF-M-NM-2 treated LSTGFBR2 cells.

Dataset Information

Deciphering the Wnt-dependent gene signature in colorectal cancer cells

Publications

Integrated genome-wide analysis of transcription factor occupancy, RNA polymerase II binding and steady-state RNA levels identify differentially regulated functional gene classes.

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