Academic literature on the topic 'NF-kB activity'

Abstract [Purpose] NF-kB has a key function in the transformation, proliferation and invasion of cancer cells as well as in resistance to radiotherapy and chemotherapy. Although constitutive NF-kB activation has been reported in many human tumors, the underlying factors and mechanisms responsible for constitutive NF-kB activation in myeloma cells has not been known. The purpose of this study was to determine the mechanism of constitutive NF-kB activity in myeloma cell lines and quantification of NF-kB activity in primary myeloma cells by expression of CD54 (a NF-kB target gene). [Methods] We checked the constitutive expression of NF-kB family proteins by western blot analysis and possible dimer formation of different NF-kB family members by Immunoprecipitation-western blot reaction. Constitutive NF-kB DNA-binding activity and dimers that are responsible for NF-kB activity were analyzed by electrophoretic mobility shift assay (EMSA). Moreover, expression of different NF-kB target genes was done by RT-PCR. [Results and discussion] Constitutive NF-kB activity was determined in myeloma cell lines and our results suggested that p50/RelB, p50/p50, p50/p52 dimers might be responsible for this. We also analyzed several NF-kB target gene expressions and found that the intensity of CD54 expression was positively correlated with total NF-kB DNA binding activity. Although there is no method to quantified NF-kB activity, it can be determine in terms of its target genes e.g. CD54. Therefore, this study provide the frame work for understanding the molecular mechanism of constitutive activation of NF-kB and would help to quantify NF-kB activation in primary myeloma cells.

Abstract [Purpose] It is considered that human myeloma cells have the constitutively high NF-kB activity involved in survival and proliferation. PPAR (Peroxisome proliferator-activated receptor) ß is ubiquitously expressed in all cells and considered to be involved in the lipid metabolism and regulating the inflammatory response and cell proliferation. We already have found that adrenal cortex hormones (DHEA and DHEA-S etc), dexamethasone (Dex) and baicalein augmented the expression of reporter gene. However, it remain to be clarified the role of PPARß in human myeloma cells. We focus on the mechanism of PPARß suppressed NF-kB activity. [Method] To know NF-kB activity of human myeloma cells, we performed EMSA with NF-kB consensus oligo. To investigate NF-kB and PPARß after stimulation of PPAR agonist, we did EMSA with NF-kB and PPAR consensus oligo. To confirm whether it is repression according the NF-kB activity suppression accompanying PPARß activation to the interaction of PPARß and NF-kB, we conducted immunoprecipitation - western blot analysis. To check whether the expression of NF-kB target genes (cIAP1, Bcl-xL, etc) were suppressed after stimulation of PPAR agonist, we performed RT-PCR analysis. [Result and discussion] It was suggested that human myeloma cell lines have constitutive NF-kB activity, and its activity mainly regulated p50. NF-kB activity and its target genes were repressed by stimulation of PPAR agonist. From the above, it was suggested that the activated PPARß interacted NF-kB and then its activity was suppressed.

Abstract Purpose Activation of canonical and noncanonical NF-kB pathways plays a key role in multiple myeloma (MM) pathogenesis. Recent studies have shown that constitutive activation of NF-kB pathways is present in ∼15-20 % of newly diagnosed MM patients. Bortezomib is a potent selective inhibitor of NF-kB activation; however its cytotoxicity is mainly due to inhibition of the noncanonical NF-kB pathway. We have previously shown that the achievement of very good partial response (VGPR) after induction therapy prior to frontline autologous stem cell transplantation (ASCT) was a favourable prognostic factor for progression-free survival (Moreau et al, Blood 2011;117:3041-3044). Our aim was to correlate NF-kB activity, reflected by a gene signature of well-known NF-kB targets, with the response rate achieved with a bortezomib-based induction regimen prior to high-dose therapy and ASCT performed as part of frontline treatment in patients with symptomatic multiple myeloma. Patients and methods One hundred and ninety-nine patients with symptomatic MM were enrolled in the prospective randomized IFM2007-02 trial comparing 4 cycles of bortezomib-dexamethasone (VD) induction therapy versus 4 cycles of the triplet combination bortezomib-thalidomide-dexamethasone (VTD) prior to ASCT. Among these 199 patients, 114 included in the present study were available for gene expression profile testing and therefore analysed for NF-kB activity. For each patient, the NF-kB(10) index, a reliable measure of NF-kB activity in MM tumor cells (Demchenko et al, Blood 2010; 115: 3541-3552) was calculated. NF-kB(10) index is based on a transcription signature of 10 genes: IL2RG, NFKB2,TNFAIP3, NFKBIE, NFKBIA, RELB, CD74, PLEK, MALT1 and WNT10. Gene expression signature was obtained from Affymetrix Exon1.0 normalized data. A high level of NF-kB activity was defined by the NF-kB(10) index found in a cohort of 20 MM patients with biallelic deletions, identified by using Affymetrix SNP6.0 data, that inactivate negative regulators (cIAP1/2) of NF-kB pathways. Response to induction therapy was evaluated according to the IMWG criteria. Results Responses to induction therapy are shown in Table 1. In this subgroup analysis, the CR plus VGPR rates were not statistically different in both arms of the trial: 24 / 54 (44%) in the VTD arm versus 21 / 60 (35%) in the VD arm, P = .35. We subsequently analyzed the correlation between NF-kB activity and response in the whole cohort of 114 patients regardless of induction treatment. We found that the level of NF-kB activity, based NF-kB(10) index, tested as a continuous variable, was strongly correlated with the quality of response, i.e. VGPR or better (P = .007 Wilcoxon test). We also investigated the cut-off value of NF-kB(10) index that could impact the response rate. Since high NF-kB(10) index was found in MM cells with known NF-kB mutations, we calculated the NF-kB(10) index in a control cohort of MM patients deleted in cIAP1/2. Patients of IFM2007-02 trial with a NF-kB(10) index (< 70.5) lower than the index of the control cohort were assigned to the low NF-kB activity group (50/114, 44%); therefore the remaining cases (64/114, 56%) presented with a high NF-kB activity. We found that patients with a reduced NF-kB(10) index displayed a significantly higher response rate (27/50; 54% vs 18/64; 28%, P= .007), as shown in Figure 1, indicating that the vast majority of patients with high NF-kB were not able to achieve at least VGPR. Conclusion Our results show that a low level NF-kB activity is associated with a higher response rate (>VGPR) to bortezomib-based induction regimen. Patients with low NF-kB(10) index represent 44% of the cohort studied. Since NK-kB activity is related to both canonical and noncanonical pathways, and knowing that bortezomib-induced cytotoxicity is mostly due to the inhibition of the noncanonical pathway only, our data strongly suggest that bortezomib should be combined with drug also targeting the canonical pathway in order to induce a high response rate in patients with increased NF-kB activity, as shown in preclinical studies (Fabre et al, Clin Cancer Res. 2012;18:4669-4681. Disclosures: Moreau: CELGENE: Honoraria, Speakers Bureau; JANSSEN: Honoraria, Speakers Bureau. Off Label Use: FRONTLINE TREATMENT WITH CARFIZOMIB. Attal:CELGENE: Honoraria, Speakers Bureau; JANSSEN: Honoraria, Speakers Bureau. Facon:Janssen and Celgene: Speakers Bureau; Millennium, Onyx, Novartis, BMS, Amgen: Membership on an entity's Board of Directors or advisory committees.

Abstract Constitutive activation of NF-kB via Bcr-Abl has been demonstrated in primary blast cells and cell lines derived from Philadelphia chromosome (Ph) -positive acute lymphoblastic leukemia (Ph-ALL). However, the microenvironmental (cytokine and/or stroma cell) regulation of NF-kB activity in Ph-ALL has not been clarified. To gain insight into these unsolved issues, we lentivirally transduced IMS-PhL1 cells with NF-kB/luciferase (kB/Luc) reporter construct and established a bioluminescence imaging model of Ph-ALL for in vitro and in vivo analysis. Unstimulated PhL1-kB/Luc cells revealed a weak but significant Luc activity over the background, verifying constitutive activation of NF-kB. Among a panel of cytokines, only TNFa potently up-regulated Luc activity in PhL1-kB/Luc cells about 10-fold over the basal level. DHMEQ, a specific inhibitor of nuclear translocation of p65, eradicated constitutive and TNFa-inducible NF-kB activity of PhL1 cells and induced their substantial apoptosis dose-dependently. A series of Ph-ALL cell lines were similarly sensitive to treatment with DHMEQ, suggesting the critical role of constitutive NF-kB activity in survival of Ph-ALL cells. When PhL1-kB/Luc cells were seeded onto a layer of murine HESS-5 stroma cells, Luc activity was not changed. Intriguingly, TNFa stimulation of PhL1-kB/Luc cells in the presence of HESS-5 cells caused synergistic enhancement of Luc activity up to 20 fold over the basal level. This up-regulation was canceled by blocking cell to cell contact with a transwell membrane, suggesting that the direct cell contact may be essential for such a synergistic effect. In HESS-5 cells, NF-kB activity was markedly augmented in response to TNFa, but this up-regulation was not sensitive to DHMEQ. Furthermore, the inhibitory effects of DHMEQ on Luc activity as well as viability of TNFa-treated PhL1-kB/Luc cells were significantly alleviated in the presence of HESS-5 cells. (Fig 1) Taken together, TNFa-triggered HESS-5 cells are likely to up-regulate NF-kB activity of PhL1 cells through DHMEQ-insensitive alternate pathway. Finally, PhL1-kB/Luc cells were transplanted into NOD-SCID mice and subjected to periodic monitoring with a CCD camera. (Fig 2) We successfully detected constitutive and TNFa-inducible bioluminescent signals of leukemia cells. Unexpectedly, by far the strongest constitutive signal was captured in the liver, although massive leukemic infiltration was observed in bone marrow and spleen, implying that hepatic microenvironment may offer proper stimuli to activate NF-kB and constitute leukemic niche. In conclusion, p65-dependent and independent pathways are involved in microenvironmental up-regulation of NF-kB activity, which contribute to survival, expansion and presumably drug-resistance of Ph-ALL cells. The present bioimaging model helps us to dissect the regulatory mechanism of NF-kB signal by cytokines and cellular interactions. Fig. 1 Up-regulation of NF-κB activity in Ph-ALL cells by cytokines and/or stroma. Fig. 2 In vivo imaging of NF-κB activity in Ph-ALL cells Fig. 1. Up-regulation of NF-κB activity in Ph-ALL cells by cytokines and/or stroma. . / Fig. 2 In vivo imaging of NF-κB activity in Ph-ALL cells

ABSTRACT Human metapneumovirus, a leading cause of respiratory tract infections in infants, encodes a small hydrophobic (SH) protein of unknown function. In this study, we showed that infection of airway epithelial cells or mice with recombinant human metapneumovirus lacking SH expression (rhMPV-ΔSH) enhanced secretion of proinflammatory mediators, including interleukin 6 (IL-6) and IL-8, encoded by two NF-kB-dependent genes, compared to infection with wild-type rhMPV. RhMPV-ΔSH infection resulted in enhanced NF-kB-dependent gene transcription and in increased levels of phosphorylated and acetylated NF-kB without affecting its nuclear translocation, identifying a possible novel mechanism by which paramyxovirus SH proteins modulate NF-kB activation.

Abstract The activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) is a very aggressive lymphoma characterized by constitutive NF-kB activation, but whether miRNAs dysfunction contributes to this event, and their exact function and mechanism remain unclear. Starting from an integrative screening strategy, we revealed that there were some interactions between the NF-kB signaling and miR-17~92 cluster, which was essential for B-cell development and commonly gained and/or overexpressed in ABC-DLBCL. Several important NF-kB negative regulators including TNFAIP3 (A20), CYLD and Rnf11 were predicted and validated to be the direct targets of miR-17~92. Conditional knock-down of miR-17~92 using sponge could suppress NF-kB activity and elevate the A20, CYLD and Rnf11 expression in 293T cells. Furthermore, we demonstrated that enforced overexpression of miR-17~92 could also decrease the A20, CYLD and Rnf11 expression in ABC-DLBCL cells. Conditional overexpression of miR-17~92 could promote ABC-DLBCL cells growth, accelerate the cells G1/G0 phase to S phase transition, and suppress NF-kB inhibitor-induced apoptosis. Conversely, conditional knock-down of miR-17~92 could inhibit ABC-DLBCL cells growth and sensitize the cells to NF-kB inhibitor-induced apoptosis. The miR-17~92 could induce the IkB-a and NF-kB p65 phosphorylation, leading to the NF-kB activation and aberrant expression of NF-kB transcriptional target genes. However, miR-17~92 did not regulate the NF-kB p52/p100 phosphorylation. Overexpression of miR-17~92 enhanced K63-linked ubiquitination and reduced K48-linked ubiquitination of the TNFa receptor 1 complex including RIP1. Importantly, we found that high expression level of miR-17~92 was associated with poorer survival in ABC-DLBCL patients. Our results uncovered a novel mechanism for the canonical but not the non-canonical transcription factor NF-kB pathway by modulation of miR-17~92 in ABC-DLBCL, and suggested that targeting the miR-17~92 might be novel bio-therapeutic strategies, which could be single-agent or combined with NF-kB inhibitor treatment, for ABC-DLBCL patients. Figure 1. Inhibition of miR-17~92 blocks the activity of NF-kB in HER293T cells: (A) The schematic representation of reporter constructs involved in assay. (B) HEK293T cells were co-transfected with Dul-Luciferase reporter constructs and the miR-17~92 sponge plasmid. TNF-a stimulation or without stimulation for 18 h. Figure 1. Inhibition of miR-17~92 blocks the activity of NF-kB in HER293T cells: (A) The schematic representation of reporter constructs involved in assay. (B) HEK293T cells were co-transfected with Dul-Luciferase reporter constructs and the miR-17~92 sponge plasmid. TNF-a stimulation or without stimulation for 18 h. Figure 2. miR-17~92 directly regulates A20, CYLD and Rnf11 in ABC-DLBCL cells. (A) Fluorescence images of tranduced ABC-DLBCL cells. (B) Expression of sponge or miR-17~92 in tranduced ABC-DLBCL cells. (C) Inhibition of miR-17~92 increase the expression of A20, CYLD and Rnf11. Overexpression of miR-17~92 reduce the expression of A20, CYLD and Rnf11 in ABC-DLBCL cells. Figure 2. miR-17~92 directly regulates A20, CYLD and Rnf11 in ABC-DLBCL cells. (A) Fluorescence images of tranduced ABC-DLBCL cells. (B) Expression of sponge or miR-17~92 in tranduced ABC-DLBCL cells. (C) Inhibition of miR-17~92 increase the expression of A20, CYLD and Rnf11. Overexpression of miR-17~92 reduce the expression of A20, CYLD and Rnf11 in ABC-DLBCL cells. Figure 3. miR-17~92 modulate mediate NF-kB activity in ABC-DLBCL. (A) Immunoblot analysis of IkB-a, NF-kB p65, NF-kB p100/p52 and their phosphorylation. (B) Heat-map display of quantitative real-time RT-PCR measurements of six independent NF-kB transcriptional targets show significantly lower expression in sponge expressing cells and higher expression in miR-17~92 expressing cells. Figure 3. miR-17~92 modulate mediate NF-kB activity in ABC-DLBCL. (A) Immunoblot analysis of IkB-a, NF-kB p65, NF-kB p100/p52 and their phosphorylation. (B) Heat-map display of quantitative real-time RT-PCR measurements of six independent NF-kB transcriptional targets show significantly lower expression in sponge expressing cells and higher expression in miR-17~92 expressing cells. Disclosures No relevant conflicts of interest to declare.

Based on the methodology of artificial neural networks, models describing the dependence of the level of RAGE inhibitory activity on the affinity of compounds for target proteins of the RAGE-NF-kB signal pathway have been costructed. A validated database of the structures and activity levels of 183 known compounds, which were tested for RAGE inhibitory activity was formed. The analysis of the AGE-RAGE signaling pathways was carried out, 14 key RAGE-NF-kB signal pathway nodes were found, for which 34 relevant target proteins were identified. A database of 66 valid 3D models of 22 target proteins of the RAGE-NF-kB signal chain was compiled. Ensemble molecular docking of 3D models of 183 known RAGE inhibitors into sites of 66 valid 3D models of 22 relevant RAGE target proteins was performed and minimum docking energies for each compound were determined for each target. According to the method of artificial multilayer perceptron neural networks, classification models were constructed to predict level of RAGE inhibitory activity based on the calculated affinity of compounds for significant target proteins of the RAGE-NF-kB signaling chain. The prognostic ability of these models of RAGE-inhibitory activity was evaluated, the maximum accuracy according to ROC-analysis was 90% for a high level of activity. The sensitivity analysis of the developed multitarget models were carried out, the most significant targets of the RAGE-NF-kB signal transmission chain were determined. It was found that for high level of RAGE inhibitory activity, the most significant biotargets are not AGE receptors, but eight signaling kinases of the RAGE-NF-kB pathway and transcription factor NF-kB1. Thus, it is suggested that known compounds with high RAGE-inhibitory activity are preferential inhibitors of signal kinases.

Abstract Abstract 1962 Poster Board I-985 Introduction: AML1/Runx1 is one of the most frequent targets of chromosomal abnormalities in human leukemia. Functional impairment of AML1 caused by point mutation is also reported in patients with leukemia or myelodysplastic syndrome (MDS). However, molecular basis for leukemogenesis caused by functional impairment of AML1 is still elusive. In this study, we clarified the deregulated signaling pathway induced by loss of AML1. Results: To find the direct target of AML1, we compared gene expression profile between AML1-conditionally deleted and normal KSL cells using Cre-ER system. Gene set enrichment analysis (GSEA) using molecular signature database (MSigDB) clarified enhanced expression of NF-kB target genes in AML1 deficient cells. In addition, NF-kB inhibitor attenuated the enhanced colony forming activity of bone marrow cells from AML1 conditional knockout (cKO) mice. These data indicate the aberrant activation of NF-kB signaling pathway in stem/progenitor cells of AML1 deficient mice. NF-kB is a transcription factor which is involved in many physiological phenomena including proliferation, survival, and inflammation. Because deregulated activation of NF-kB signaling has been reported to be responsible for many types of tumors including hematological malignancies, we assumed that lack of AML1-mediated suppression of NF-kB signaling lead to malignant transformation of hematopoietic cells. p65, one of the major components of NF-kB stays in cytoplasm with IkB in a steady state. Once receiving stimulating signals from cell surface receptors such as TNF-a receptor, IkB is phosphorylated by IKK complex and subsequently degraded through the ubiquitin-proteasome pathway, resulting in nuclear translocation of p65 and transactivation of NF-kB target genes. First, we found that AML1 inhibits nuclear translocation of p65 and that nuclear localization of p65 is enhanced in AML1 deficient cells, which is cancelled by NF-kB inhibitors. In addition, AML1 inhibited p65 phosphorylation at serine 536, which is important for its activation. We found that AML1 physically interacts with IKK complex and thus suppresses its kinase activity, which accounts for a mechanistic basis for inhibition of NF-kB signaling by AML1. Suppression of IKK kinase activity by AML1 results in inhibition of both nuclear translocation of p65 and activation of NF-kB target genes. Next, we examined how leukemia-related AML1 mutants affect NF-kB signaling. Remarkably, AML1 D171N mutant found in MDS neither inhibited nuclear translocation of p65 nor attenuated the kinase activity of IKK complex. Similar results were obtained with AML1/ETO generated in leukemia with t(8;21). Mouse bone marrow cells immortalized by AML1/ETO showed enhanced nuclear localization of p65 compared with those immortalized by MLL/ENL, another leukemia-related fusion protein. Indeed, AML1/ETO immortalized cells are more sensitive to NF-kB inhibitor-mediated growth suppression, indicating a critical role of NF-kB signaling in transformation by AML1/ETO. To verify the activation of NF-kB signaling by AML1/ETO in human hematopoietic cells, we analyzed the gene expression data reported by Valk et al. in silico. We found that NF-kB signaling is distinctly activated in AML1-related leukemia patients. These results suggest that aberrant activation of NF-kB signaling induced by functional impairment of AML1 may contribute to the development of leukemia via proliferation signals. Conclusions: We found that AML1 is a cytoplasmic attenuator of NF-kB signaling pathway. Functional impairment of AML1 caused by genetic disruption results in distinct activation of NF-kB signaling by altering IKK kinetic activity. This aberrant activation may play a central role in pathogenesis of AML1-related leukemia and MDS. Therefore, NF-kB signaling is one of the attractive candidates for molecular targeted therapy against AML1-related hematological disorders. Disclosures: No relevant conflicts of interest to declare.

In the last decade there has been a thriving development of quantitative methods in the field of biomedical physics, both in the modeling of biological complex systems and in the statistical analysis of experimental results. In this thesis we examine the effect of a variety of stimuli on the NF-kB activity's oscillation in metastatic colorectal cancer cells using probabilistic models such as the Chemical Master Equation and the Bayesian statistics. After a brief introduction we explain the theoretical foundations of the Master Equation approach and of the Bayesian inference, together with a brief dip in the subject of Hamiltonian Monte Carlo methods. In the continuation we create a solvable model using the Master Equation approach and we gain insights concerning its eigenvalues distribution in the complex plane. We therefore build a Bayesian regression model and we use it to analyze the oscillating autocorrelation function of the previous stochastic model in order to test the capabilities of the statistical model. Finally we analyze the biological data using the previously created and tested statistical model, exploring and commenting the results and outlining further research directions.

Stimulation of Toll-like receptors (TLRs) in cells of the innate immune system activates the expression of a proinflammatory and antimicrobial gene program controlled by a network of transcriptional regulators. We show that NFAT5, which belongs to the Rel family of transcription factors and was previously characterized as an osmostress responsive factor, is required for the expression of a group of TLR-responsive genes in macrophages, such as Nos2, Il6 and Tnf. NFAT5 recruitment to its target genes is dependent on IKKβ activity, de novo protein synthesis and is sensitive to histone deacetylases. Interestingly, NFAT5 is essential in the response to low doses of TLR ligands, regulating specific gene subsets depending on the stimulus strength. We also show that macrophages use NFAT5 to facilitate chromatin accessibility, allowing the recruitment of transcriptional regulators such as p65/NF-κB, c-Fos and p300 to its target regions. We use Nos2 as a gene whose induction is NFAT5-dependent especially at low doses of LPS to demonstrate that NFAT5 controls the recruitment of p65 by facilitating the activity of H3K27 demethylases, without influencing the binding of Polycomb repressive complex 2 or JMJD3. Altogether, this thesis characterizes NFAT5 as a novel regulator of the immune response to low pathogen load involved in the control of local chromatin accessibility.
En las células del sistema inmunitario innato, la estimulación de los receptores de tipo Toll (TLR) activa la expresión de un programa génico pro-inflamatorio y antimicrobiano que está controlado por una red de reguladores transcripcionales. Hemos demostrado que el NFAT5, perteneciente a la familia de factores de transcripción Rel y previamente caracterizado como un factor de respuesta a estrés osmótico, es importante para la expresión de un grupo de genes de respuesta a TLRs, entre ellos Nos2, Il6 y Tnf. El reclutamiento del NFAT5 a sus genes diana requiere la actividad de IKKβ, la síntesis de novo de proteínas y es sensible a la acción de las deacetilasas de histonas. Resulta interesante el hecho de que el NFAT5 es esencial para responder a bajas dosis de ligando de los TLRs, y que regula grupos de genes específicos dependiendo de la intensidad del estímulo. También mostramos que NFAT5 facilita la accesibilidad de la cromatina en macrófagos, permitiendo el reclutamiento de reguladores transcripcionales como p65/NF-kB, c-Fos y p300 a sus regiones diana. Utilizando Nos2 como un gen cuya inducción es más dependiente de NFAT5 a bajas dosis de LPS, demostramos que el NFAT5 controla el reclutamiento de p65 gracias a que facilita la actividad de las demetilasas de H3K27, pero sin influir en la unión del complejo Polycomb 2 ni JMJD3. En conclusión, esta tesis caracteriza al NFAT5 como un nuevo regulador del sistema inmunitario implicado en el control de la accesibilidad local de la cromatina en respuesta a baja carga de patógenos.

La maggior parte dei tumori riescono ad evadere il sistema immunitario inibendo l’espressione di antigeni tumorali associati alle molecole del complesso maggiore di istocompatibilità di classe I (MHC I) sulla superficie cellulare. La mancata espressione di questi complessi è spesso dovuta alla presenza di difetti strutturali dei geni codificanti le molecole MHC I, oppure all’aberrante espressione delle molecole responsabili del processamento degli antigeni legati alle molecole MHC I. Il neuroblastoma (NB), il tumore extracraniale solido più comune dell’infanzia, non è un’eccezione. Sia la maggior parte delle linee cellulari di NB, che i tumori primari esprimono bassi, se non nulli, livelli di MHC I che possono essere aumentati trattando le cellule con l’interferone-gamma (IFN-γ). Questo fenotipo è compatibile con la presenza di difetti nella regolazione trascrizionale delle molecole coinvolte nel processamento e nella presentazione dell’antigene. Il presente studio ha lo scopo di indagare il meccanismo molecolare che determina la mancata o ridotta espressione delle molecole MHC I, e delle due aminopeptidasi del reticolo endoplasmatico ERAP1 ed ERAP2. Le forme più aggressive di NB sono caratterizzate dall’amplificazione dell’oncogene MYCN. Sebbene una correlazione inversa tra l’espressione di MYCN le molecole MHC I nelle linee cellulari umane di NB sia stata riportata, un coinvolgimento diretto di MYCN nella regolazione di MHC I non è stato dimostrato. I nostri risultati dimostrano che MYCN non è responsabile dei bassi livelli di MHC I, ERAP1 ed ERAP2 nelle cellule di NB analizzate, infatti la loro espressione non è influenzata nè dalla forzata espressione ne dall’inibizione di MYCN. Abbiamo invece identificato due fattori di trascrizione, NF-kB e IRF1, che sono direttamente coinvolti nella regolazione delle proteine MHC I ed ERAPs. Mediante il saggio di immunoprecipitazione della cromatina abbiamo dimostrato che il reclutamento di p65 (una subunità di NF-kB) sui promotori di MHC I, ERAP1 ed ERAP2 è direttamente proporzionale all’espressione di questi geni. Inoltre, il fenotipo negativo per MHC I, ERAP1 ed ERAP2, caratteristico delle forme più aggressive di NB, coincide con una bassa attività nucleare di NF-kB ed IRF1. L’overespressione dei due fattori trascrizionali da soli è in grado di recuperare solo parzialmente l’espressione di MHC I, ERAP1 ed ERAP2, inoltre il risultato dipende dalla linea cellulare trasfettata. Comunque, la trasfezione contemporanea di NF-kB ed IRF1 produce un incremento sinergico dei geni target in tutte le linee trasfettate. Degno di nota è il fatto che l’espressione di p65 nei tumori primari di neuroblastoma è simile a quella osservata nelle linee cellulari. Infatti, solo le cellule gangliari, ovvero le cellule più differenziate presenti nel tessuto tumorale, esprimono sia l’MHC I che il p65 nucleare. Quindi, questo studio mette in luce il meccanismo molecolare responsabile della mancata espressione delle molecole MHC I, ERAP1 ed ERAP2 nei tumori di neuroblastoma più aggressivi fornendo un importante punto di partenza per lo sviluppo di protocolli immunoterapeutici più efficaci basati sull’utilizzo delle cellule T.
Low expression of major histocompatibility complex class I (MHC I) molecules on the cell surface allows tumors to evade the host T cell-based immune response. These abnormalities are often related to either genetic defects of MHC I genes or aberrant expression of antigen processing machinery (APM) components. Neuroblastoma (NB), the most common solid extracranial cancer of childhood, is not an exception. MHC I surface expression is virtually undetectable in the most NB cell lines and primary tumors, and upregulated by gamma-interferon (IFN-γ). This phenotype is compatible with defects in the regulation of antigen processing and presentation components. In this study, the molecular mechanism underlying low immunogenicity in neuroblastoma was investigated. Amplification of the MYCN oncogene characterizes the most aggressive forms of NB and is believe to downregulate expression of MHC class I molecules. Although an inverse correlation between MYCN and MHC I has been reported in human NB cell lines, a direct demonstration of the MYCN-mediated down-regulation of MHC I expression has been questioned. Herein, we demonstrate that MYCN is not responsible for low MHC I, ERAP1 and ERAP2 protein levels in human NB cell lines, since their expression is not affected by neither transfection-mediated overexpression nor siRNA suppression of MYCN. Instead, we identified NF-kB and IRF1 as the main factors involved in the transcriptional regulation of MHC I and ERAPs proteins. By chromatin immunoprecipitation assay, we show a recruitment of p65 NF-kB to the MHC I, ERAP1 and ERAP2 promoters that is proportional with the expression of these genes. Moreover, low nuclear activity of both NF-kB and IRF1 factors correlated with the MHC I, ERAP1 and ERAP2-low phenotype of the most aggressive NB cell lines. Overexpression of either the transcription factors alone rescued the MHC I, ERAP1 and ERAP2-low phenotype, but only partially and in a cell-type depending manner. Important, the co-transfection of both NF-kB and IRF1 cooperated to strongly enhance the transactivation of MHC I, ERAP1 and ERAP2 in any cell lines. Notheworthy, NF-kB and IRF1 acted in a synergistic manner. We found an intriguing parallel in primary NB tumors, in fact, nuclear p65 was detected in the maturing neuroblastic cells (i.e. ganglionic cells) which express higher levels of MHC I molecules in human NB specimens. These findings provide molecular insight into defective MHC I expression in NB tumors and indicate that activating NF-kB and IRF1 in MHC I-low, aggressive NB cells could be instrumental for successful application of T cell-based immunotherapy.

Thesis (Ph. D.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains xi, 147 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 128-143).

The tumor necrosis factor (TNF) receptor-associated factors (TRAFs) were initially discovered as proteins that inducibly interact with the intracellular region of TNF receptors (TNFRs). Because the TNFRs lack intrinsic catalytic activity, the TRAFs are hypothesized to orchestrate signaling activation downstream of the TNFR superfamily, however their mechanism of activation remains unclear (Inoue et al., 2000; Bishop, 2004). Originally, the TRAFs were compared to the signal transducers and activators of transcription (STAT) protein family, due to their sequence homology, and the presence of multiple RING- and zinc-finger domains, suggesting that their function may be to regulate transcriptional activity (Rothe et al., 1994; Hu et al., 1994; Sato et al. 1995; Cheng et al., 1995). However, subsequent research focused predominantly on their cytoplasmic functions, and more recently on their function as E3 ubiquitin ligases (Pineda et al., 2007). In my research, I analyzed the subcellular localizations of the TRAFs following CD40 ligand (CD40L)-stimulation, and found that TRAF2 and 3 rapidly translocate into the nucleus of primary neurons and Neuro2a cells. Interestingly, similar analysis conducted in pre-B lymphocytes (Daudi cells) revealed a different response to CD40L-stimulation, with TRAF2 and 3 being rapidly degraded within 5-minutes of stimulation. These findings are significant because they demonstrate for the first time that the TRAFs translocate into the nucleus and suggest that they may function within the nucleus in a cell-specific manner. I next analyzed the ability of TRAF2 and 3 to bind to DNA, and found that they both bind to chromatin and the NF-kappaB consensus element in Neuro2a cells, following CD40L-stimulation. Similar analyses of the chromatin binding of TRAF2 and 3 in Daudi cells revealed that they were rapidly degraded, similar to the results from my analysis of their subcellular localization. These findings show for the first time that the TRAFs interact with DNA, and therefore support the hypothesis that the TRAFs may function within the nucleus as transcriptional regulators. Finally, I analyzed the ability of the TRAFs to regulate transcriptional activity by luciferase assay. Previous studies showed that overexpression of TRAF2 and 6 could induce NF-kappaB transcriptional activity; however researchers have not been able to determine the mechanism by which they do so. In my studies, I found that every TRAF can directly regulate transcriptional activity either as co-activators or co-repressors of transcription, in a cell- and target protein-specific manner. Additionally, I found that TRAF2 can act as a transcriptional activator, and that its ability to regulate transcription is largely dependent upon the presence of its RING-finger domain. In conclusion, these studies have revealed an entirely novel function for the TRAFs as immediate-early transcriptional regulators. Future research into the genes that are regulated by the specific TRAF complexes will further elucidate how the TRAFs regulate TNFR signaling, as well as whether dysfunctions in TRAF signaling may be associated with known disorders. If specific TRAF complexes are found to regulate specific genes, then pharmacological targeting of the individual TRAF complexes may allow for the highly specific inhibition of signaling events downstream of the TNFRs, without compromising overall receptor signaling, transcription factor pathways, or cellular systems.

INTRODUCTION AGEs and ALEs (Advanced Glycoxidation/Lipoxidation End products) are covalently modified proteins that can act as pathogenic factors in several chronic diseases, like diabetes and cardiovascular diseases. These covalent adducts are formed by different mechanisms. AGEs are proteins covalently modified by reducing sugars or their oxidative degradation products, involving the Maillard reaction. ALEs are proteins modified by reactive carbonyl species (RCS) generated by lipid peroxidation. AGEs/ALEs can be the basis of many different pathologies, underlining the importance for good analytical methods for identification and characterization for the use of biomarkers, but also as a drug target. However, the identification, characterization and quantification of AGEs/ALEs remains to be very challenging due to heterogeneous precursors (sugars, lipids) leading to heterogeneous AGEs/ALEs, present in low concentrations and being very complex analytes. Various techniques to identify and characterize AGEs/ALEs have been described, making use of an isolation/enrichment step based on reactive groups, like carbonyls. However, not all AGEs/ALEs retain reactive groups and therefore can not be isolated and identified using these techniques, indicating the need for a new strategy. The strategy that has been employed in our laboratory is to use the soluble domain of the RAGE receptor, VC1, to affinity enrich AGEs. Using this approach, AGEs/ALEs will be enriched independently of the protein and type of modification. Moreover, a ligand of RAGE can be identified, which could be a potential biomarker of a disease caused by oxidative stress. RAGE is a type I cell surface receptor that is expressed in several cells, such as endothelial cells, smooth muscle cells, but also dendritic cells and T-lymphocytes and is predominantly located in the lungs. The receptor has been implicated in many different pathologies with a marked oxidative base, such as diabetes, atherosclerosis and neurodegenerative diseases. One of the pathways that can be activated is the Nf-κB pathway. The Nf-κB pathway is the ideal signaling pathway to investigate the binding and activation of RAGE by AGEs or ALEs. For this purpose, a cell line was obtained with and without overexpression of RAGE. Furthermore, the cell lines were transfected with a Nf-κB reporter gene, providing us with a fast and high-throughput assay for the evaluation of a pro-inflammatory response upon stimulation with AGEs/ALEs. AIM OF THE PROJECT The identification and characterization of AGEs/ALEs has proven to be crucial in the onset and development of many pathologies. Therefore, good analytical strategies need to be developed/optimized for better understanding of the exact nature of modification, to understand the role they play in disease progression. Identified AGEs/ALEs can serve as biomarker, as well as drug targets. The VC1 technique was proven to be a promising technique to accommodate the need for enrichment of AGEs for better characterization. The first aim of the project was therefore to investigate whether also ALEs are binder of RAGE, since they share the same structural properties than AGEs, and also have been shown to activate the Nf-κB pathway, implicating a role for receptors, like RAGE. Furthermore, to gain a deeper insight into the molecular mechanisms involved in the protein-protein engagement. Since a successful enrichment strategy was developed, the second aim of this project was focused on identifying AGEs/ALEs in biological samples. The first part was focused on oxidizing healthy human plasma in-vitro using AAPH as a radical initiator, and the incubation of plasma directly with RCS, anticipating the production of AGEs/ALEs. The VC1 technique was then used to identify which AGEs/ALEs are produced. Simultaneously, other variables during the sample preparation and analysis were optimized. As explained before, AGEs/ALEs are present in very low concentrations in biological samples, hence the need for very sensitive methods and instrumentation allowing identification. Since human serum albumin (HSA) is the main protein present in plasma, around 50-60%, and has multiple nucleophilic targets, it represents the best model for characterizing AGEs/ALEs. For this reason, the focus was on extracting HSA from plasma, using the newest generation of tribrid MS for the analysis of AGEs/ALEs in plasma samples. AGEs are ligands for RAGE, meaning, they can bind and activate the receptor, inducing a signaling pathway and pro-inflammatory response. ALEs have also been shown to induce a pro-inflammatory response; however, no specific receptor has been linked to this cellular event. Using a cell line with and without RAGE, we aimed to determine whether ALEs can bind and activate the Nf-κB pathway through RAGE. RESULTS AND DISCUSSION ALEs as binder of RAGE In order to investigate the interaction between RAGE and ALEs, different ALEs were produced in-vitro by incubating HSA with different concentrations of well-known lipid derived RCS and in particular: ACR, MDA and HNE. After 24, 48 and 72 h, aliquots of the incubation mixtures were withdrawn, and the reaction was stopped by removing the excess of RCS by ultrafiltration. Intact protein analysis by direct infusion MS was used to evaluate the extent of HSA modifications and demonstrated that by using a wide range of molar ratios and different time-points a quite wide array of ALEs for each tested RCS was generated. In order to characterize ALEs selectively enriched by RAGE, a VC1 pull-down assay was performed as previously described. HSA and HSA treated with MDA, ACR or HNE were assayed for binding to VC1-resins and to control resin. As expected, unmodified HSA was not retained by the VC1-resin. At increasing molar ratios and incubation time, higher amounts of albumin modified with MDA or ACR were eluted from the VC1 resin, with a predominance of the high molecular weight (HMW) species. The modified albumins were retained by the VC1-resin, but not by the control resin. ALEs in the reaction mixtures and those enriched by VC1 were analyzed by bottom-up MS in order to identify the PTMs and to localize the amino acid residues involved in the protein adduct formation. With regard to MDA, only di-hydropyridine adducts on lysines (DHPK), and N-2-pyrimidyl-ornithine adducts on arginines (NPO) were retained by VC1-domain. The n-propenal modifications of lysine (NPK), largely identified before enrichment, were not identified after the enrichment. ACR induced a set of modifications which were identified only after VC1 enrichment and in particular the N-(3-formyl-3,4-dehydro-piperidinyl) lysine (FDPK) modifications, the Michael adduct on cysteines, the double Michael adduct of lysines, the Michael adduct of histidine, the N-2-(4 hydroxy-tetrahydro-pyrimidyl) ornitine (propane-arginine, HTPO) and the Nε-(3-methylpyridinium)-lysine (MP-lysine). Most of the ALEs generated by HNE were found both before or after enrichment, with the exception of a few Michael adducts which were selectively retained by VC1 (not detected before enrichment). With a view to rationalizing the key factors influencing the RAGE binding of the monitored adducts, in silico studies were performed. They were focused on the adducts on arginine and lysine residues as formed by ACR and MDA since they are numerous, with a very broad range of affinity, thus allowing the development of clear structure-affinity relationships. RAGE-ligand interacting regions are characterized by a rich set of positively charged residues which can bind acidic regions of a protein. The mechanism identified using in silico studies, involves a basic amino acid at the center of carboxylic acids like glutamate and aspartate, which forms a set of ionic bridges. Once the basic amino acid is modified by ACR or MDA to an adduct with a neutral charge, the carboxylic acids become available to freely contact the RAGE positive residues. Identification of AGEs/ALEs in biological samples The VC1 technique has proven to be successful in enriching AGEs and ALEs, so the next step was to exploit this technique in biological samples. In order to identify proteins prone to be modified due to oxidative pathways, and possibly serve as biomarker, healthy human plasma was oxidized using the radical initiator AAPH. Different concentrations of AAPH and different timepoints were tested for the presence of protein carbonyl groups, an indicator for protein oxidation and possibly the formation of AGEs/ALEs. A time and concentration dependent formation of carbonyl groups is observed in plasma. Next, samples were analyzed using a bottom-up approach. Results obtained were showing many oxidation products, such as amino side chain oxidation, however no AGEs/ALEs were identified. Thus, a new approach was adopted, including the incubation of plasma directly with RCS, such as HNE, MDA and ACR. This resulted in the formation of AGEs/ALEs in plasma samples, however, they could not be retained by the VC1 domain. Instead of using the VC1 technique to enrich AGEs/ALEs from biological samples, other variables throughout the experimental set-up were optimized. Previously, peptides were analyzed using the Orbitrap LTQ XL, a very powerful instrument. Nonetheless, the newest generation of tribrid MS offers even higher resolution, and it increases protein coverage due to parallel isolation and detection, and faster analyzers. Moreover, we focused on AGEs/ALEs from HSA and using NaBH4 to reduce and stabilize adducts throughout the analysis. This new approach permitted us to identify many AGEs/ALEs in both healthy human plasma samples, but also AGEs/ALEs only present in heart failure samples. Glycation on lysine residues was the main modification identified, present in both healthy and heart failure plasma samples. Important is the HNE Michael adduct, specifically identified in only heart failure samples. Moreover, the importance of stabilizing adducts is underlined by the fact that the acrolein Michael adduct could only be identified after reduction with NaBH4. Development of a cellular assay to determine pro-inflammatory activity of RAGE binders Another part of this project was focused on elucidating whether AGEs/ALEs induce an inflammatory response in cells. For this purpose, a collaboration was started with the Laboratory of Vascular Biology and Regenerative Medicine, Centro Cardiologico Monzino. Using a rat epithelial lung cell line overexpressing RAGE, and a control cell line not expressing RAGE, it could be detected if AGEs/ALEs exhibit an effect by binding to RAGE. Moreover, both cell lines were transfected with a Nf-κB reporter gene allowing us a fast and sensitive method for determining if binding of RAGE induces a down-stream signaling pathway. This system implies a firefly luciferase gene downstream from the Nf-κB gene. When the Nf-κB pathway is activated, independently from RAGE, it produces the firefly luciferase enzyme. After adding a luciferin substrate, firefly luciferase is able to convert this substrate into another substrate with light as by-product, which can be measured by a luminometer. IL-1α was used as a positive control, since it induces a strong inflammatory response through Nf-κB. Moreover, known ligands of RAGE able to activate the Nf-κB pathway, were used to validate the cellular experiment, including HSA modified with fructose (AGE), and HMGB1. Results show that Nf-κB is already increased in untreated cells with RAGE and that AGEs induce the Nf-κB pathway independently from RAGE. Moreover, the difference between control and RAGE cells is not significantly increased in the presence of HMGB1 compared to untreated. However, the positive control seemed to induce a much stronger activity in cells with RAGE. Overall, this cellular assay is good for assessing pro-inflammatory activity, however, it is not optimized yet for distinguishing a RAGE-dependent mechanism. CONCLUSION In summary, by using an integrated MS (intact protein and bottom-up approach) and computational approach we have found that some ALEs generated from lipid peroxidation RCS are RAGE binders. We have also found the basic features that ALEs from HNE, MDA and ACR must have to be a RAGE binder: 1) the covalent adducts should greatly reduce or abolish the basicity of the target amino acid, 2) the basic amino acid should be at the center of a set of carboxylic acids which, once the residue is modified, become available to freely contact the RAGE positive residues. Next step was to use the VC1 technique to enrich AGEs/ALEs in biological samples. First, oxidized human plasma was used, however, using the Orbitrap LTQ XL, it was not sufficient to identify AGEs/ALEs. Therefore, analysis was moved to a higher resolution mass spectrometer, which allowed us to identify AGEs/ALEs in plasma samples of heart failure patients, showing the powerfulness of this new generation MS. Important was to understand whether ALEs could induce pro-inflammatory activity through RAGE, since we showed that ALEs are RAGE binders. Unfortunately, the cellular assay that was set up is efficiently in determining Nf-κB dependent pro-inflammatory activity, but not if it is RAGE dependent.

Le rôle important des facteurs de transcription tels que STAT3 et NF-kB dans les processus biologiques, ainsi que leur implication dans l’oncogenèse, justifient les nombreuses études consacrées à ces facteurs. Inhiber leurs activités semble présenter un grand intérêt thérapeutique. Dans un premier temps, nous avons montré que STAT3 est activé dans le cancer du côlon et qu’il est associé à des facteurs histopronostiques. Dans un deuxième temps, nous nous sommes intéressés à l’inhibition de facteurs de transcription STAT3 et NF-kB par des oligonucléotides leurres (ODN) comportant les séquences consensus de ces facteurs. Les ODN leurres induisent la mort d’une lignée cellulaire de cancer du côlon dont la croissance est sous la dépendance de STAT3 et NF-kB. Cependant, l’ODN anti-STAT3 peut interagir avec STAT1 et bloquer l’action de l’IFN. Ainsi, il est intéressant d’inhiber des facteurs de transcription dans les cellules tumorales mais les questions de spécificité ne sont pas résolues
The important role of transcription factors such as STAT3 and Nf-kB in biological processes, and their involvement in oncogenesis, justifies the numerous studies on these factors. To inhibit and control their activities appears to be promising therapeutic approach. Firstly, we have shown that STAT3 is constitutively activated in colon cancer and is associated with histopronostics features. In secondly, we inhibited the transcription factors STAT3 and NF-kB in cancer cell lines, we using decoy oligonucleotide containing the consensus target ssequences of these two factors. The decoy oligonucleotides induce the death of a cell line of colon cancer (SW480), however, the decoy ODN of STAT3 was found to interact with STAT1 and prevent IFNy action. Thus, it's of interest to inhibit transcription factors in tumor cells but specific issues are not resolved