Tumor suppression via inhibition of SWI/SNF complex-dependent NF-kappaB activation
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE93770 | GEO | 2017/09/22
SECONDARY ACCESSION(S): PRJNA362335
REPOSITORIES: GEO
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Project description:The transcription factor NF-κB is constitutively activated in many epithelial tumors but few NF-κB inhibitors are suitable for cancer therapy because of its broad biological effects. We previously reported that the d4-family proteins (DPF1, DPF2, DPF3a/b) function as adaptor proteins linking NF-κB with the SWI/SNF complex. Here, using epithelial tumor cell lines, A549 and HeLaS3, we demonstrate that exogenous expression of the highly-conserved N-terminal 84-amino acid region (designated "CT1") of either DPF2 or DPF3a/b has stronger inhibitory effects on anchorage-independent growth than the single knockdown of any d4-family protein. This indicates that CT1 can function as an efficient dominant-negative mutant of the entire d4-family proteins. By in situ proximity ligation assay, CT1 was found to retain full adaptor function, indicating that the C-terminal region of d4-family proteins lacking in CT1 would include essential domains for SWI/SNF-dependent NF-κB activation. Microarray analysis revealed that CT1 suppresses only a portion of the NF-κB target genes, including representative SWI/SNF-dependent genes. Among these genes, IL6 was shown to strongly contribute to anchorage-independent growth. Finally, exogenous CT1 expression efficiently suppressed tumor formation in a mouse xenograft model, suggesting that the d4-family proteins are promising cancer therapy targets.
| S-EPMC5603518 | biostudies-literature
Project description:The transcription factor NF-kappaB is constitutively activated in many epithelial tumors but few NF-kappaB inhibitors are suitable for cancer therapy because of the broad biological effects of NF-κB. We previously reported that the d4 family (DPF1, DPF2, DPF3a/b) function as adaptor proteins linking NF-kappaB with the SWI/SNF complex. Here, we demonstrate that in epithelial tumor cell lines, exogenous expression of the highly conserved N-terminal 84-amino acid region of either DPF2 or DPF3a/b (designated “CT1”) has stronger inhibitory effects on anchorage-independent growth than single knockdown of any d4 protein, indicating that CT1 can function as an efficient dominant-negative mutant of the entire d4 family. By proximity ligation assays, CT1 was further shown to retain full function as an adaptor. Microarray analysis categorized NF-kappaB target genes by their CT1 sensitivity. Among CT1-sensitive genes, IL-6 was shown to strongly contribute to the anchorage-independent growth. Finally, exogenous CT1 expression efficiently suppressed tumor formation in a mouse xenograft model, suggesting that the d4 protein family could be a promising cancer therapy target.
2017-09-22 | GSE93768 | GEO
Project description:The transcription factor NF-kappaB is constitutively activated in many epithelial tumors but few NF-kappaB inhibitors are suitable for cancer therapy because of the broad biological effects of NF-κB. We previously reported that the d4 family (DPF1, DPF2, DPF3a/b) function as adaptor proteins linking NF-kappaB with the SWI/SNF complex. Here, we demonstrate that in epithelial tumor cell lines, exogenous expression of the highly conserved N-terminal 84-amino acid region of either DPF2 or DPF3a/b (designated “CT1”) has stronger inhibitory effects on anchorage-independent growth than single knockdown of any d4 protein, indicating that CT1 can function as an efficient dominant-negative mutant of the entire d4 family. By proximity ligation assays, CT1 was further shown to retain full function as an adaptor. Microarray analysis categorized NF-kappaB target genes by their CT1 sensitivity. Among CT1-sensitive genes, IL-6 was shown to strongly contribute to the anchorage-independent growth. Finally, exogenous CT1 expression efficiently suppressed tumor formation in a mouse xenograft model, suggesting that the d4 protein family could be a promising cancer therapy target. TNF-alpha induced gene expression in HeLaS3 cells was measured at 0 and 1 hour after the treatment of TNF-alpha (10 ng/ml). Beforehand, the cells were transduced with either lentivirus vector expressing a dominant-negative mutant of d4-family protein (named CT1) or with empty vector (control).
2017-09-22 | GSE93769 | GEO
Project description:Tumor suppression via inhibition of SWI/SNF complex-dependent NF-kappaB activation
| PRJNA362335 | ENA
Project description:The SWI/SNF chromatin remodeling complex plays pivotal roles in mammalian transcriptional regulation. In this study, we identify the human requiem protein (REQ/DPF2) as an adaptor molecule that links the NF-kappaB and SWI/SNF chromatin remodeling factor. Through in vitro binding experiments, REQ was found to bind to several SWI/SNF complex subunits and also to the p52 NF-kappaB subunit through its nuclear localization signal containing the N-terminal region. REQ, together with Brm, a catalytic subunit of the SWI/SNF complex, enhances the NF-kappaB-dependent transcriptional activation that principally involves the RelB/p52 dimer. Both REQ and Brm were further found to be required for the induction of the endogenous BLC (CXCL13) gene in response to lymphotoxin stimulation, an inducer of the noncanonical NF-kappaB pathway. Upon lymphotoxin treatment, REQ and Brm form a larger complex with RelB/p52 and are recruited to the BLC promoter in a ligand-dependent manner. Moreover, a REQ knockdown efficiently suppresses anchorage-independent growth in several cell lines in which the noncanonical NF-kappaB pathway was constitutively activated. From these results, we conclude that REQ functions as an efficient adaptor protein between the SWI/SNF complex and RelB/p52 and plays important roles in noncanonical NF-kappaB transcriptional activation and its associated oncogenic activity.
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Project description:Expression of the adenovirus E1A243 oncoprotein in Saccharomyces cerevisiae produces a slow-growth phenotype with accumulation of cells in the G1 phase of the cell cycle. This effect is due to the N-terminal and CR1 domains of E1A243, which in rodent cells are involved in triggering cellular transformation and also in binding to the cellular transcriptional coactivator p300. A genetic screen was undertaken to identify genes required for the function of E1A243 in S. cerevisiae. This screen identified SNF12, a gene encoding the 73-kDa subunit of the SWI/SNF transcriptional regulatory complex. Mutation of genes encoding known members of the SWI/SNF complex also led to loss of E1A function, suggesting that the SWI/SNF complex is a target of E1A243. Moreover, expression of E1A in wild-type cells specifically blocked transcriptional activation of the INO1 and SUC2 genes, whose activation pathways are distinct but have a common requirement for the SWI/SNF complex. These data demonstrate a specific functional interaction between E1A and the SWI/SNF complex and suggest that a similar interaction takes place in rodent and human cells.
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Project description:Transcriptional activation of yeast INO1 requires SWI/SNF and INO80 for nucleosome disruption at the promoter. However, the cooperative interplay among remodelers and their recruitment dynamics in activation have thus far been vague. Here, we showed, using chromatin immunoprecipitation, that both SWI/SNF and INO80 are present at the promoter and are restricted to the promoter, indicating that they directly participate in localized INO1 chromatin remodeling. Furthermore, both SWI/SNF and INO80 are absent at the INO1 promoter in ino2Delta cells, suggesting that these are activator-dependent remodelers. We have also found that the presence of INO80 is required for SWI/SNF recruitment, indicating that INO80 arrives first at the promoter followed by SWI/SNF. In light of these findings, we proposed a model which describes the order of events in INO1 activation.
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Project description:LncRNAs have been shown to be direct players in chromatin regulation, but little is known about their role at active genomic loci. We investigate the role of lncRNAs in gene activation by profiling the RNA interactome of SMARCB1-containing SWI/SNF complexes in proliferating and senescent conditions. The isolation of SMARCB1-associated transcripts, together with chromatin profiling, shows prevalent association to active regions where SMARCB1 differentially binds locally transcribed RNAs. We identify SWINGN, a lncRNA interacting with SMARCB1 exclusively in proliferating conditions, exerting a pro-oncogenic role in some tumor types. SWINGN is transcribed from an enhancer and modulates the activation of GAS6 oncogene as part of a topologically organized region, as well as a larger network of pro-oncogenic genes by favoring SMARCB1 binding. Our results indicate that SWINGN influences the ability of the SWI/SNF complexes to drive epigenetic activation of specific promoters, suggesting a SWI/SNF-RNA cooperation to achieve optimal transcriptional activation.
| S-EPMC7028943 | biostudies-literature
Project description:We have previously shown that DPF2 (requiem/REQ) functions as a linker protein between the SWI/SNF complex and RelB/p52 NF-?B heterodimer and plays important roles in NF-?B transactivation via its noncanonical pathway. Using sensitive 293FT reporter cell clones that had integrated a SWI/SNF-dependent NF-?B reporter gene, we find in this study that the overexpression of DPF1, DPF2, DPF3a, DPF3b, and PHF10 significantly potentiates the transactivating activity of typical NF-?B dimers. Knockdown analysis using 293FT reporter cells that endogenously express these five proteins at low levels clearly showed that DPF3a and DPF3b, which are produced from the DPF3 gene by alternative splicing, are the most critical for the RelA/p50 NF-?B heterodimer transactivation induced by TNF-? stimulation. Our data further show that this transactivation requires the SWI/SNF complex. DPF3a and DPF3b are additionally shown to interact directly with RelA, p50, and several subunits of the SWI/SNF complex in vitro and to be co-immunoprecipitated with RelA/p50 and the SWI/SNF complex from the nuclear fractions of cells treated with TNF-?. In ChIP experiments, we further found that endogenous DPF3a/b and the SWI/SNF complex are continuously present on HIV-1 LTR, whereas the kinetics of RelA/p50 recruitment after TNF-? treatment correlate well with the viral transcriptional activation levels. Additionally, re-ChIP experiments showed DPF3a/b and the SWI/SNF complex associate with RelA on the endogenous IL-6 promoter after TNF-? treatment. In conclusion, our present data indicate that by linking RelA/p50 to the SWI/SNF complex, DPF3a/b induces the transactivation of NF-?B target gene promoters in relatively inactive chromatin contexts.
| S-EPMC3320940 | biostudies-literature
Project description:BackgroundSilicosis is a complex lung disease for which no successful treatment is available and therefore lung transplantation is a potential alternative. Tumor necrosis factor alpha (TNFalpha) plays a central role in the pathogenesis of silicosis. TNFalpha signaling is mediated by the transcription factor, Nuclear Factor (NF)-kappaB, which regulates genes controlling several physiological processes including the innate immune responses, cell death, and inflammation. Therefore, inhibition of NF-kappaB activation represents a potential therapeutic strategy for silicosis.Methods/findingsIn the present work we evaluated the lung transplant database (May 1986-July 2007) at the University of Pittsburgh to study the efficacy of lung transplantation in patients with silicosis (n = 11). We contrasted the overall survival and rate of graft rejection in these patients to that of patients with idiopathic pulmonary fibrosis (IPF, n = 79) that was selected as a control group because survival benefit of lung transplantation has been identified for these patients. At the time of lung transplantation, we found the lungs of silica-exposed subjects to contain multiple foci of inflammatory cells and silicotic nodules with proximal TNFalpha expressing macrophage and NF-kappaB activation in epithelial cells. Patients with silicosis had poor survival (median survival 2.4 yr; confidence interval (CI): 0.16-7.88 yr) compared to IPF patients (5.3 yr; CI: 2.8-15 yr; p = 0.07), and experienced early rejection of their lung grafts (0.9 yr; CI: 0.22-0.9 yr) following lung transplantation (2.4 yr; CI:1.5-3.6 yr; p<0.05). Using a mouse experimental model in which the endotracheal instillation of silica reproduces the silica-induced lung injury observed in humans we found that systemic inhibition of NF-kappaB activation with a pharmacologic inhibitor (BAY 11-7085) of IkappaB alpha phosphorylation decreased silica-induced inflammation and collagen deposition. In contrast, transgenic mice expressing a dominant negative IkappaB alpha mutant protein under the control of epithelial cell specific promoters demonstrate enhanced apoptosis and collagen deposition in their lungs in response to silica.ConclusionsAlthough limited by its size, our data support that patients with silicosis appear to have poor outcome following lung transplantation. Experimental data indicate that while the systemic inhibition of NF-kappaB protects from silica-induced lung injury, epithelial cell specific NF-kappaB inhibition appears to aggravate the outcome of experimental silicosis.
| S-EPMC2682759 | biostudies-literature