Project description:The NF-κB pathway is a critical regulator of the immune system and has been implicated in cellular transformation and tumorigenesis. NF-κB response is regulated by the activation state of the IκB kinase (IKK) complex and triggered by a wide spectrum of stimuli. We previously reported that NF-κB is downstream of Notch1 in T cell acute lymphoblastic leukaemia (T-ALL), however both the mechanisms involving Notch1-induced NF-κB activation and the potential importance of NF-κB in the maintenance of the disease are unknown. Here we visualize Notch-induced NF-κB activation using both human T-ALL cell lines and animal models of this type of leukemia. We show that it is not Notch1 itself but Hes1, a canonical Notch target, the responsible for sustaining IKK activation in T-ALL. Hes1 exerts its effects by a direct transcriptional repression of the deubiquitinating enzyme CYLD, a well-characterized IKK inhibitor. Consistently, CYLD expression is significantly reduced in primary T-ALL leukemias. Finally, we demonstrate that IKK complex inhibition is a promising option for the targeted therapy of T-ALL as suppression of IKK function affected both the survival of human T-ALL cells in vitro and the maintenance of the disease in vivo. Transcriptional consequences of NF-kB inactivation in human T-ALL1 cell line
Project description:The NF-M-NM-:B pathway is a critical regulator of the immune system and has been implicated in cellular transformation and tumorigenesis. NF-M-NM-:B response is regulated by the activation state of the IM-NM-:B kinase (IKK) complex and triggered by a wide spectrum of stimuli. We previously reported that NF-M-NM-:B is downstream of Notch1 in T cell acute lymphoblastic leukaemia (T-ALL), however both the mechanisms involving Notch1-induced NF-M-NM-:B activation and the potential importance of NF-M-NM-:B in the maintenance of the disease are unknown. Here we visualize Notch-induced NF-M-NM-:B activation using both human T-ALL cell lines and animal models of this type of leukemia. We show that it is not Notch1 itself but Hes1, a canonical Notch target, the responsible for sustaining IKK activation in T-ALL. Hes1 exerts its effects by a direct transcriptional repression of the deubiquitinating enzyme CYLD, a well-characterized IKK inhibitor. Consistently, CYLD expression is significantly reduced in primary T-ALL leukemias. Finally, we demonstrate that IKK complex inhibition is a promising option for the targeted therapy of T-ALL as suppression of IKK function affected both the survival of human T-ALL cells in vitro and the maintenance of the disease in vivo. Transcriptional consequences of NF-kB inactivation in human T-ALL1 cell line Twenty samples were analyzed: human T-ALL, CEM, KOPT-K, DND41, HPB-ALL cells lines have been treated at 100uM for 16 hours with control peptide or IKKM-NM-3 Nemo binding domain (NBD) inhibitory peptide, that specifically block the canonical NF-M-NM-:B activity by disrupting the interaction of IKKM-NM-3 to IKKM-NM-2 and IKKM-NM-1
Project description:Notch signaling plays both oncogenic and tumor suppressor roles, depending on cell type. In contrast to T cell acute lymphoblastic leukemia (T-ALL), where Notch activation promotes leukemogenesis, induction of Notch signaling in B-ALL leads to growth arrest and apoptosis. The Notch target Hairy/Enhancer of Split1 (HES1) is sufficient to reproduce this tumor suppressor phenotype in B-ALL, however the mechanism is not yet known. Here we report that HES1 regulates pro-apoptotic signals via the novel interacting protein Poly ADP-Ribose Polymerase1 (PARP1) in a cell type-specific manner. The interaction of HES1 with PARP1 inhibits HES1 function, induces PARP1 activation and results in PARP1 cleavage in B-ALL. HES1-induced PARP1 activation leads to self-ADP ribosylation of PARP1, consumption of NAD+, diminished ATP levels, and translocation of the Apoptosis Inducing Factor (AIF) from mitochondria to the nucleus, resulting in apoptosis in B-ALL, but not T-ALL. Importantly, induction of Notch signaling via the Notch agonist peptide DSL can reproduce these events and leads to BALL apoptosis. The novel interaction of HES1 and PARP1 in B-ALL modulates the function of the HES1 transcriptional complex and signals through PARP1 to induce apoptosis. This mechanism reveals a cell type-specific pro-apoptotic pathway which may lead to Notch agonist-based cancer therapeutics. Study involved the gene expression profiling of human acute lymphoblastic leukemia samples, and comparison of the levels of expression NOTCH1 pathway genes and targets across ALL subtypes
Project description:In this study, we describe a novel relationship between glioblastoma CSCs and the Notch pathway, which involves the constitutive activation of STAT3 and NF-κB signaling. We demonstrate that adherent glioma CSCs exhibit characteristics previously described for CSCs grown in suspension culture. The expression of CD133, Sox2 and Nestin increased when compared to glioma cells grown in monolayer, and the adherent CSCs were ~100 times more tumorigenic in vivo than monolayer cultured glioma cells. We also found that while the STAT3 and NF-κB signaling pathways are constitutively activated in glioma lines, these pathways are dramatically activated in glioma CSCs. Treatment with STAT3 inhibitors led to a loss of nuclear activation of STAT3 signaling and suppression of growth in both monolayer and CSC conditions. There was a markedly greater growth suppressive effect on glioma CSCs, suggesting that targeted therapy of these key pathways in glioma CSCs may be possible. To further investigate potential biomarkers in glioma CSCs, microarray analysis was performed and revealed deregulation of the Notch signaling pathway. This constitutive activation of STAT3, NF-κB, and Notch pathways in glioma CSCs helps identify novel therapeutic targets for the treatment of glioma. GBM6 cells were continuously maintained as subcutaneous xenografts in NSG mice, and monolayer and CSC cultures were derived from freshly harvested tumor tissue. A total of 6 samples were subjected to microarray analysis, with three biological replicates for each experimental condition.
Project description:Notch signaling plays both oncogenic and tumor suppressor roles, depending on cell type. In contrast to T cell acute lymphoblastic leukemia (T-ALL), where Notch activation promotes leukemogenesis, induction of Notch signaling in B-ALL leads to growth arrest and apoptosis. The Notch target Hairy/Enhancer of Split1 (HES1) is sufficient to reproduce this tumor suppressor phenotype in B-ALL, however the mechanism is not yet known. Here we report that HES1 regulates pro-apoptotic signals via the novel interacting protein Poly ADP-Ribose Polymerase1 (PARP1) in a cell type-specific manner. The interaction of HES1 with PARP1 inhibits HES1 function, induces PARP1 activation and results in PARP1 cleavage in B-ALL. HES1-induced PARP1 activation leads to self-ADP ribosylation of PARP1, consumption of NAD+, diminished ATP levels, and translocation of the Apoptosis Inducing Factor (AIF) from mitochondria to the nucleus, resulting in apoptosis in B-ALL, but not T-ALL. Importantly, induction of Notch signaling via the Notch agonist peptide DSL can reproduce these events and leads to BALL apoptosis. The novel interaction of HES1 and PARP1 in B-ALL modulates the function of the HES1 transcriptional complex and signals through PARP1 to induce apoptosis. This mechanism reveals a cell type-specific pro-apoptotic pathway which may lead to Notch agonist-based cancer therapeutics.
Project description:<p>Nasopharyngeal carcinoma (NPC) is an aggressive head and neck cancer characterized by Epstein-Barr virus (EBV) infection and dense lymphocyte infiltration. The scarcity of NPC genomic data hinders the understanding of NPC biology, disease progression, and rational therapy design. Here, we performed whole-exome sequencing (WES) on 111 micro-dissected EBV-positive NPCs, with 15 cases subjected to further whole-genome sequencing (WGS), to determine its mutational landscape. We identified enrichment for genomic aberrations of multiple negative regulators of the NF-kB pathway in a total of 41% of cases including CYLD, TRAF3, NFKBIA and NLRC5. Functional analysis confirmed novel inactivating CYLD mutations as drivers for NPC cell growth. The EBV oncoprotein latent member protein 1 (LMP1) functions to constitutively activate NF-kB signaling, and we observed mutual exclusivity among somatic NF-kB pathway aberrations and LMP1-overexpression, suggesting that NF-kB activation is selected for by both somatic and viral events during NPC pathogenesis.</p>
Project description:In this study, we describe a novel relationship between glioblastoma CSCs and the Notch pathway, which involves the constitutive activation of STAT3 and NF-κB signaling. We demonstrate that adherent glioma CSCs exhibit characteristics previously described for CSCs grown in suspension culture. The expression of CD133, Sox2 and Nestin increased when compared to glioma cells grown in monolayer, and the adherent CSCs were ~100 times more tumorigenic in vivo than monolayer cultured glioma cells. We also found that while the STAT3 and NF-κB signaling pathways are constitutively activated in glioma lines, these pathways are dramatically activated in glioma CSCs. Treatment with STAT3 inhibitors led to a loss of nuclear activation of STAT3 signaling and suppression of growth in both monolayer and CSC conditions. There was a markedly greater growth suppressive effect on glioma CSCs, suggesting that targeted therapy of these key pathways in glioma CSCs may be possible. To further investigate potential biomarkers in glioma CSCs, microarray analysis was performed and revealed deregulation of the Notch signaling pathway. This constitutive activation of STAT3, NF-κB, and Notch pathways in glioma CSCs helps identify novel therapeutic targets for the treatment of glioma.
Project description:The NF-κB pathway is a master regulator of inflammatory processes and is implicated in insulin resistance and pancreatic beta cell dysfunction in the metabolic syndrome. While canonical NF-κB signaling is well studied, there is little information on the divergent non-canonical NF-κB pathway in the context of pancreatic islet dysfunction in diabetes. Here, we demonstrate that pharmacological activation of the non-canonical NF-κB inducing kinase (NIK) disrupts glucose homeostasis in zebrafish in vivo. Further, we identify NIK as a critical negative regulator of beta cell function as pharmacological NIK activation results in impaired glucose-stimulated insulin secretion in mouse and human islets. NIK levels are elevated in pancreatic islets isolated from diet-induced obese (DIO) mice, which exhibit increased processing of non-canonical NF-κB components p100 to p52, and accumulation of RelB. Tumor necrosis factor α (TNFα) and receptor activator of NF-κB ligand (RANKL), two ligands associated with diabetes, induce NIK in islets. Mice with constitutive beta cell intrinsic NIK activation present impaired insulin secretion with DIO. NIK activation triggers the non-canonical NF-κB transcriptional network to induce genes identified in human type 2 diabetes genome-wide association studies linked to beta cell failure. These studies reveal that NIK contributes a central mechanism for beta cell failure in diet-induced obesity. We identify a role for Nuclear Factor inducing κB (NIK) in pancreatic beta cell failure. NIK activation disrupts glucose homeostasis in zebrafish in vivo and impairs glucose-stimulated insulin secretion in mouse and human islets in vitro. NIK activation also perturbs beta cell insulin secretion in a diet-induced obesity mouse model. These studies reveal that NIK contributes a central mechanism for beta cell failure in obesity. To uncover the role of NIK in pancreatic beta cells, we performed a gene expression microarray analysis comparing pancreatic islets with constitutive beta cell intrinsicNIK activation from the 16 week old mice (beta cell specific TRAF2 and TRAF2 knockout mice) to their controls (n=3 per group).
Project description:Mesenchymal stem cells (MSCs) are known to induce the conversion of activated T-cells into regulatory T-cells in vitro. The marker CD69 is a target of canonical NF-κB signaling and is transiently expressed upon activation; however, stable CD69 expression defines cells with immunoregulatory properties. Given its enormous therapeutic potential, we explored the molecular mechanisms underlying the induction of regulatory cells by MSCs. Peripheral blood CD3+ T-cells were activated and cultured in the presence or absence of MSCs. CD4+ cell mRNA expression was then characterized by microarray analysis. The drug BAY11-7082 and a siRNA against RELB were used to explore the differential roles of canonical and non-canonical NF-κB signaling, respectively. Flow cytometry and real-time PCR were used for analyses. Genes with immunoregulatory functions, CD69 and non-canonical NF-κB subunits (RELB and NFKB2) were all expressed at higher levels in lymphocytes co-cultured with MSCs. The frequency of CD69+ cells among lymphocytes cultured alone progressively decreased after activation. In contrast, the frequency of CD69+ cells increased significantly following activation in lymphocytes co-cultured with MSCs. Inhibition of canonical NF-κB signaling by BAY immediately following activation blocked the induction of CD69; however, inhibition of canonical NF-κB signaling on the 3rd day further induced the expression of CD69. Furthermore, late expression of CD69 was inhibited by RELB siRNA. These results indicate that the canonical NF-κB pathway controls the early expression of CD69 after activation; however, in an immunoregulatory context, late and sustained CD69 expression is promoted by the non-canonical pathway and is inhibited by canonical NF-κB signaling. In order to study the molecular basis by which Multipotent Mesenchymal Stromal/Stem Cells (MSC) exert their immune regulatory function, immunomagnetically purified CD3+ T-cells from the peripheral blood of 3 individuals were activated and cultured in the presence or absence of MSCs. Following 5 days, CD4+ and CD8+ T-cells were further immunomagnetically selected and their gene expression profiles were obtained by microarrays and compared. Paired samples from 3 individuals were used for this analysis.
Project description:Previous studies linked mac activation with the ubiquitination (ub) status of key proteins in inflammatory signal pathways. Lysine-48 ub (K48-ub) of the NF-κB inhibitor (IκB), the final checkpoint of the NFκB pathway, leads to IκB degradation and consequent NF-κB-associated inflammation. In contrast, TRAF6, an upstream positive regulator of the NF-κB pathway, is modulated by K63-ub, leading to its conformational change and activation. However, a comprehensive analysis of ub profiles of polarized macs has not been reported. If a unique ub signature is associated with individual mac subsets is not known.