Project description:1. To identify potential effectors responsible for anti-tumorigenesis by targeting PLD1, we performed microarray in two Wnt-relevant colon cancer cells and analyzed transcriptional profile of genes that were differently expressed by inhibition and knockdown of PLD1 2. We also investigated potential downstream effectors of PLD1-E2F1 axis using microarray analysis in PLD1 and E2F1-depleted CRC cells.
Project description:The specific ablation of Rb1 gene in epidermis (RbF/F;K14cre) promotes proliferation and altered differentiation but does not produce spontaneous tumour development. These phenotypic changes are associated with increased expression of E2F members and E2F-dependent transcriptional activity. Here, we have focused on the possible dependence on E2F1 gene function. We have generated mice that lack Rb1 in epidermis in an inducible manner (RbF/F;K14creERTM). These mice are indistinguishable from those lacking pRb in this tissue in a constitutive manner (RbF/F;K14cre). In an E2F1-null background (RbF/F;K14creERTM; E2F1-/- mice), the phenotype due to acute Rb1 loss is not ameliorated by E2F1 loss, but rather exacerbated, indicating that pRb functions in epidermis do not rely solely on E2F1. On the other hand, RbF/F;K14creERTM;E2F1-/- mice develope spontaneous epidermal tumours of hair follicle origin with high incidence. These tumours, which retain a functional p19arf/p53 axis, also show aberrant activation of βcatenin/Wnt pathway. Gene expression studies revealed that these tumours display relevant similarities with specific human tumours. These data demonstrate that the Rb/E2F1 axis exerts essential functions not only in maintaining epidermal homeostasis, but also in suppressing tumour development in epidermis, and that the disruption of this pathway may induce tumour progression through specific alteration of developmental programs. Gene expression was compared between normal mouse skin, skin from transgenic RbF/F;K14creERTM; E2F1-/- , E2F1-/-, and RbF/F;K14creERTM; E2F1-/- mouse, and carcinomas arising in the skin of RbF/F;K14creERTM; E2F1-/- mouse. All mice were treated with tamoxifen.
Project description:Colon cancers typically contain tumor cell populations with differential WNT signaling activity. Colon cancer cells with high WNT-activity have been attributed increase tumorigenic potential and stem cell characteristics. We extracted tumor cells with differential WNT activity using fluorescent reporters from xenografted human colon cancer cell line tumors and primary human colon cancer xenografts and analysed their gene expression profiles.
Project description:In response to polarization cues, cultured Caco-2 cells, a human colon adenocarcinoma-derived cell line, form a polarized epithelium resembling normal enterocytes. We investigated potential signaling mechanisms activated by Caco-2 cells that might trigger the genome-wide transcriptional reprogramming that accompanies polarization (Saaf et al, submitted-I). cDNA microarrays were used to compare the transcriptional profile of Caco-2 polarization to the gene expression profiles of normal human colon and colon tumors. The transcript profile of proliferating, non-polarized Caco-2 cells has striking parallels to the gene expression profile of human colon cancer in vivo. However, as Caco-2 cells develop polarity, the gene expression profile shifts to one more closely resembling that of normal colon tissue, suggesting that the underlying regulatory mechanisms that mediate Caco-2 cell polarization are similar to those that occur during in vivo enterocyte differentiation. We show that transcriptional re-programming of Caco-2 cells during development of cell polarity occurs in the context of signaling pathways that are regulated in a manner that is remarkably similar to those in normal intestinal development. For example, transcriptional targets of the Wnt pathway are tightly regulated during Caco-2 cell polarization, mimicking the gradient of Wnt-mediated transcription in the crypt (high expression) to villus (low expression) axis in human intestine. However, Caco-2 cells lack full-length APC necessary for normal Wnt-regulated degradation of beta-catenin. Biochemical analysis indicates that regulation of the Wnt pathway occurs in the nucleus at the level of activation of target genes by the beta-catenin-TCF complex, revealing a novel additional mechanism by which intestinal cells may regulate Wnt signaling during their maturation. In addition, other signaling pathways including Notch, BMP, Hedgehog, and growth factor, were temporally regulated during Caco-2 cell polarization. Surprisingly, modulation of these signaling pathways in Caco-2 cells occurs in the absence of morphogen gradients and interactions with stromal cells characteristic of enterocyte differentiation in situ. This dataset contains gene expression profiles of 9 normal colon samples and 15 colon tumor samples. Samples of tumor and normal colon mucosa were collected from colon cancer resection from Department of Surgery, Queen Mary Hospital University of Hong Kong. Tissue was frozen in liquid nitrogen within 30 min of resection. Nonneoplastic mucosa from colon was dissected free of muscle and histologically confirmed to be tumor free by frozen section. Total RNA was extracted using Trizol (Invitrogen, Carlsbad, CA) from each tissue sample and processed for microarray hybridization. A disease state experiment design type is where the state of some disease such as infection, pathology, syndrome, etc is studied. Disease State: Tumor/Normal colon samples Using regression correlation
Project description:Colon cancers typically contain tumor cell populations with differential WNT signaling activity. Colon cancer cells with high WNT-activity have been attributed increase tumorigenic potential and stem cell characteristics. We extracted tumor cells with differential WNT activity using fluorescent reporters from xenografted human colon cancer cell line tumors and primary human colon cancer xenografts and analysed their gene expression profiles. Colon cancer cell lines and primary colon cancer xenografts were transduced with lentiviral TOP-GFP reporters, and grown as xenografts in NOD-SCID mice. We disaggregated these tumors, flow sorted for GFPhigh and GFPlow tumor cells and subjected these populations to gene expression profiling.
Project description:In response to polarization cues, cultured Caco-2 cells, a human colon adenocarcinoma-derived cell line, form a polarized epithelium resembling normal enterocytes. We investigated potential signaling mechanisms activated by Caco-2 cells that might trigger the genome-wide transcriptional reprogramming that accompanies polarization (Saaf et al, submitted-I). cDNA microarrays were used to compare the transcriptional profile of Caco-2 polarization to the gene expression profiles of normal human colon and colon tumors. The transcript profile of proliferating, non-polarized Caco-2 cells has striking parallels to the gene expression profile of human colon cancer in vivo. However, as Caco-2 cells develop polarity, the gene expression profile shifts to one more closely resembling that of normal colon tissue, suggesting that the underlying regulatory mechanisms that mediate Caco-2 cell polarization are similar to those that occur during in vivo enterocyte differentiation. We show that transcriptional re-programming of Caco-2 cells during development of cell polarity occurs in the context of signaling pathways that are regulated in a manner that is remarkably similar to those in normal intestinal development. For example, transcriptional targets of the Wnt pathway are tightly regulated during Caco-2 cell polarization, mimicking the gradient of Wnt-mediated transcription in the crypt (high expression) to villus (low expression) axis in human intestine. However, Caco-2 cells lack full-length APC necessary for normal Wnt-regulated degradation of beta-catenin. Biochemical analysis indicates that regulation of the Wnt pathway occurs in the nucleus at the level of activation of target genes by the beta-catenin-TCF complex, revealing a novel additional mechanism by which intestinal cells may regulate Wnt signaling during their maturation. In addition, other signaling pathways including Notch, BMP, Hedgehog, and growth factor, were temporally regulated during Caco-2 cell polarization. Surprisingly, modulation of these signaling pathways in Caco-2 cells occurs in the absence of morphogen gradients and interactions with stromal cells characteristic of enterocyte differentiation in situ. This dataset contains gene expression profiles of 9 normal colon samples and 15 colon tumor samples. Samples of tumor and normal colon mucosa were collected from colon cancer resection from Department of Surgery, Queen Mary Hospital University of Hong Kong. Tissue was frozen in liquid nitrogen within 30 min of resection. Nonneoplastic mucosa from colon was dissected free of muscle and histologically confirmed to be tumor free by frozen section. Total RNA was extracted using Trizol (Invitrogen, Carlsbad, CA) from each tissue sample and processed for microarray hybridization. A disease state experiment design type is where the state of some disease such as infection, pathology, syndrome, etc is studied. Disease State: Tumor/Normal colon samples Keywords: disease_state_design
Project description:To identify potential miRNA effectors responsible for anti-tumorigenesis by targeting PLD1, we performed miRNA microarray in Wnt-relevant colon cancer cells and analyzed miRNAs that were differently expressed by inhibition of PLD1
Project description:The specific ablation of Rb1 gene in epidermis (RbF/F;K14cre) promotes proliferation and altered differentiation but does not produce spontaneous tumour development. These phenotypic changes are associated with increased expression of E2F members and E2F-dependent transcriptional activity. Here, we have focused on the possible dependence on E2F1 gene function. We have generated mice that lack Rb1 in epidermis in an inducible manner (RbF/F;K14creERTM). These mice are indistinguishable from those lacking pRb in this tissue in a constitutive manner (RbF/F;K14cre). In an E2F1-null background (RbF/F;K14creERTM; E2F1-/- mice), the phenotype due to acute Rb1 loss is not ameliorated by E2F1 loss, but rather exacerbated, indicating that pRb functions in epidermis do not rely solely on E2F1. On the other hand, RbF/F;K14creERTM;E2F1-/- mice develope spontaneous epidermal tumours of hair follicle origin with high incidence. These tumours, which retain a functional p19arf/p53 axis, also show aberrant activation of βcatenin/Wnt pathway. Gene expression studies revealed that these tumours display relevant similarities with specific human tumours. These data demonstrate that the Rb/E2F1 axis exerts essential functions not only in maintaining epidermal homeostasis, but also in suppressing tumour development in epidermis, and that the disruption of this pathway may induce tumour progression through specific alteration of developmental programs.
Project description:The purpose of this study was to determine how IGF2BP1 affects non-transformed and colorectal cancer (CRC) cells' expression of the genes regulated by Wnt/β-catenin signaling. The study established that while the majority of upregulated genes in non-transformed cells were activated by Wnt ligand treatment independent of IGF2BP1, a subset of Wnt-induced genes was regulated by IGF2BP1, including 11 direct binding targets. In contrast, in CRC cells where Wnt signaling is constitutively active, the majority of downregulated genes upon β-catenin/Tcf7l2 blockage were regulated by IGF2BP1, and 17 of these genes were identified as direct binding targets of IGF2BP1. Our iCLIP study identified a shift in the binding regions along target transcriptomes with modulations in Wnt signaling. Furthermore, the study found a significant change in the enrichment of 6-mer motifs associated with IGF2BP1 binding in response to Wnt signaling in both cell types, suggesting a role for Wnt signaling in regulating IGF2BP1 binding specificity. The study also revealed a signature of IGF2BP1-regulated genes that are significantly associated with colon cancer-free survival in humans, as well as potential targets for colon cancer treatment, including MGAT5 and MET. Overall, this study highlights the complex and context-dependent regulation of Wnt signaling target genes by IGF2BP1 in non-transformed and CRC cells and identifies potential targets for colon cancer treatment.