Project description:The tetraspanin CD63 is implicated in pro-metastatic signaling pathways, but so far, it is unclear how CD63 levels affect the tumor cell phenotype. Here, we investigated the effect of CD63 modulation in different metastatic tumor cell lines. In vitro, knock down of CD63 induced a more epithelial-like phenotype concomitant with increased E-cadherin expression, downregulation of its repressors Slug and Zeb1, and decreased N-cadherin. In addition, β-catenin protein was markedly reduced, negatively affecting expression of the target genes MMP-2 and PAI-1. β-catenin inhibitors mimicked the epithelial phenotype induced by CD63 knock down. Inhibition of β-catenin upstream regulators PI3K/AKT or GSK3β could rescue the mesenchymal phenotype underlining the importance of the β-catenin pathway in CD63-regulated cell plasticity. CD63 knock down-induced phenotypical changes correlated with a decrease of experimental metastasis, while CD63 overexpression enhanced the tumor cell-intrinsic metastatic potential. Taken together, our data show that CD63 is a crucial player in the regulation of the tumor cell-intrinsic metastatic potential by affecting cell plasticity. Stable knock down of CD63 was performed in SKOV3ipL ovarian carcinoma cell line using 2 shRNAs lentiviral constructs (sh49 and sh51), and as a negative control, a shNT construct. Parental cells, control shNT and the 2 shCD63 cell lines were seeded 24 hours prior to RNA isolation on a 10 cm dish, labelling and hybridization on microarrays. One color experiment with 2 biological replicates of the 4 experimental conditions: SKOV3ipL, SKOV3ipL_shNT, SKOV3ipL_sh49 and SKOV3ipL_sh51.
Project description:The tetraspanin CD63 is implicated in pro-metastatic signaling pathways, but so far, it is unclear how CD63 levels affect the tumor cell phenotype. Here, we investigated the effect of CD63 modulation in different metastatic tumor cell lines. In vitro, knock down of CD63 induced a more epithelial-like phenotype concomitant with increased E-cadherin expression, downregulation of its repressors Slug and Zeb1, and decreased N-cadherin. In addition, β-catenin protein was markedly reduced, negatively affecting expression of the target genes MMP-2 and PAI-1. β-catenin inhibitors mimicked the epithelial phenotype induced by CD63 knock down. Inhibition of β-catenin upstream regulators PI3K/AKT or GSK3β could rescue the mesenchymal phenotype underlining the importance of the β-catenin pathway in CD63-regulated cell plasticity. CD63 knock down-induced phenotypical changes correlated with a decrease of experimental metastasis, while CD63 overexpression enhanced the tumor cell-intrinsic metastatic potential. Taken together, our data show that CD63 is a crucial player in the regulation of the tumor cell-intrinsic metastatic potential by affecting cell plasticity.
Project description:Deregulation of canonical Wnt/beta-catenin pathway is one of the earliest events in the pathogenesis of colon cancer. Mutations in APC or CTNNB1 (beta-catenin gene) are highly frequent in colon cancer and cause aberrant stabilization of b-catenin, which activates the transcription of Wnt target genes by binding to chromatin via the TCF/LEF transcription factors. Here we report an integrative analysis of genome-wide chromatin occupancy of b-catenin by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) and gene expression profiling by microarray analysis upon RNAi-mediated knockdown of beta-catenin in colon cancer cells (GSE53656). Immunoprecipitated samples from human colon cancer SW480 cells with antibodies against beta-catenin and control IgG respectively were used for ChIP-seq experiments.
Project description:Transcription factors harbour defined intrinsically disordered regulatory regions, which raises the question of how they mediate binding to structured co-regulators and how this regulates activity. Here, we present a detailed molecular regulatory mechanism of Forkhead box O4 (FOXO4) by the structured transcriptional co-regulator β-catenin. We find that the largely disordered FOXO4 C-terminal region, which contains its transactivation domain binds β-catenin through two defined interaction sites, and this is regulated by combined PKB/AKT- and CK1-mediated phosphorylation. Binding of β-catenin competes with the auto-inhibitory interaction of the FOXO4 disordered region with its DNA-binding forkhead domain, and thereby enhances FOXO4 transcriptional activity. Furthermore, we show that binding of the β-catenin inhibitor protein ICAT is compatible with FOXO4 binding to β-catenin, suggesting that ICAT acts as a molecular switch between anti-proliferative FOXO and pro-proliferative Wnt/TCF/LEF signalling. Together these data illustrate how the interplay of intrinsically disordered regions, post-translational modifications and co-factor binding contribute to transcription factor function. Highlights • The interaction network between FOXO4 and β-catenin was deciphered • FOXO4 auto-inhibition interferes with DNA binding and is counter-acted by β-catenin • FOXO4 exists in multiple conformations regulated by phosphorylation and co-factors • ICAT switches between FOXO4 and TCF/LEF transcription factors
Project description:The main cause of malignancy-related mortality is metastasis. While metastatic progression is driven by diverse tumor-intrinsic mechanisms, there is a growing appreciation for the contribution of tumor-extrinsic elements of the tumor microenvironment (TME), especially macrophages. Recruited macrophages infiltrating the TME are correlated with worse outcomes, because they are rendered pro-tumorigenic through defined tumor-driven transcription factor-mediated programs. However, the pathways that govern the dysregulation of tissue-resident macrophages (TRMs) are less well understood. Alveolar macrophages (AMs) are a TRM population with critical roles in both tissue homeostasis and metastasis. Wnt/β-catenin signaling is a hallmark of cancer and has been identified as a pathologic regulator of AMs in infection. We tested the hypothesis that β-catenin expression in AMs enhances metastasis in solid tumor models. Using a novel genetic β-catenin gain-of-function approach, we demonstrated that 1) enhanced β-catenin in AMs heightened lung metastasis; 2) β-catenin activity in AMs drove a dysregulated inflammatory program strongly associated with Tnf expression; and 3) localized TNF blockade abrogated this metastatic outcome. Lastly, CTNNB1 and TNF expression were positively correlated in AMs of lung cancer patients. Overall, our findings revealed a novel Wnt/β-catenin–TNF-α pro-metastatic axis in AMs with potential therapeutic implications against tumors refractory to TNF-α induced necrosis.
Project description:The tetraspanin protein CD63 has been recently described as a key factor in extracellular vesicle (EV) production and endosomal cargo sorting. In this study, we assemble a global scope of CD63-dependent protein trafficking into small secreted vesicles.
Project description:Gain-of-function mutations in exon 3 of beta-catenin (CTNNB1) are specific for Wilms' tumors that have lost WT1, but 50% of WT1-mutant cases lack such "hot spot" mutations. To ask whether stabilization of beta-catenin might be essential after WT1 loss, and to identify downstream target genes, we compared expression profiles in WT1-mutant versus WT1 wild-type Wilms' tumors. Supervised and nonsupervised hierarchical clustering of the expression data separated these two classes of Wilms' tumor. The WT1-mutant tumors overexpressed genes encoding myogenic and other transcription factors (MOX2, LBX1, SIM2), signaling molecules (TGFB2, FST, BMP2A), extracellular Wnt inhibitors (WIF1, SFRP4), and known beta-catenin/TCF targets (FST, CSPG2, CMYC). Beta-Catenin/TCF target genes were overexpressed in the WT1-mutant tumors even in the absence of CTNNB1 exon 3 mutations, and complete sequencing revealed gain-of-function mutations elsewhere in the CTNNB1 gene in some of these tumors, increasing the overall mutation frequency to 75%. Lastly, we identified and validated a novel direct beta-catenin target gene, GAD1, among the WT1-mutant signature genes. These data highlight two molecular classes of Wilms' tumor, and indicate strong selection for stabilization of beta-catenin in the WT1-mutant class. Beta-Catenin stabilization can initiate tumorigenesis in other systems, and this mechanism is likely critical in tumor formation after loss of WT1. Experiment Overall Design: Identification of WNT/Beta-Catenin or WT1 target genes. 39 individual samples.
Project description:Deregulation of canonical Wnt/beta-catenin pathway is one of the earliest events in the pathogenesis of colon cancer. Mutations in APC or CTNNB1 (beta-catenin gene) are highly frequent in colon cancer and cause aberrant stabilization of b-catenin, which activates the transcription of Wnt target genes by binding to chromatin via the TCF/LEF transcription factors. Here we report an integrative analysis of genome-wide chromatin occupancy of b-catenin by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) and gene expression profiling by microarray analysis upon RNAi-mediated knockdown of beta-catenin in colon cancer cells (GSE53656).
Project description:Malignant melanoma is characterized by frequent metastasis, however specific changes that regulate this process have not been clearly delineated. Although it is well known that Wnt signaling is frequently dysregulated in melanoma, the functional implications of this observation are unclear. By modulating beta-catenin levels in a mouse model of melanoma that is based on melanocyte-specific Pten loss and BrafV600E mutation, we demonstrate that beta-catenin is a central mediator of melanoma metastasis to lymph node and lung. In addition to altering metastasis, beta-catenin levels control tumor differentiation and regulate both MAPK/Erk and PI3K/Akt signaling. Highly metastatic tumors with beta-catenin stabilization are very similar to a subset of human melanomas; together these findings establish Wnt signaling as a metastasis regulator in melanoma. MoGene-1_0-st-v1: Four samples total. Two biological replicates of uncultured Pten/Braf murine melanomas and two biological replicates of uncultured Pten/Braf/Bcat-STA murine melanomas. MoEx-1_0-st-v1: Two samples total. Dissociated tumor and FACS-enriched Pten/Braf and Pten/Braf/Bcat-STA murine melanoma.
Project description:Deregulation of the canonical Wnt/beta-catenin pathway is one of the earliest events in the pathogenesis of colon cancer. Mutations in APC or CTNNB1 are frequent in colon cancer and cause aberrant stabilization of beta-catenin, which activates Wnt target genes by binding to chromatin via TCF/LEF transcription factors. In a comprehensive study, we conducted an integrative analysis of genome-wide chromatin occupancy of beta-catenin by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) along with gene expression profiling changes resulting from RNAi-mediated knockdown of beta-catenin in colon cancer cells. This experiment series represents the gene expression changes detected by microarray as a result of CTNNB1 perturbation. SW480 cells were transfected with control and beta-catenin siRNAs. Twenty-four hours after transfection, RNA was extracted from the cells using the RNeasy kit (Qiagen, Valencia, CA) and genome-wide cDNA microarray expression analysis was performed. The data reported here are the microarray data as processed by the standard Rosetta Resolver(R) ratio method for Agilent microarrays.