NF-kappaB DNA Binding Research Articles

Nuclear Factor-kappa B Is Not Involved in Titanium DioxideInduced Inflammation

Research over recent years have shown that titanium dioxide (TiO2) nanoparticles (NPs) induce inflammation in various lung, kidney, liver and brain cells. Although the mechanism of inflammation is unclear, existing literature suggests the underlying role of oxidative stress. On the other hand, it has also been shown that nuclear factor-kappa B (NF-kappaB) is activated in response to pro-inflammatory cytokines. In this study we investigated the involvement of NF-kappaB in TiO2-induced inflammation in human lung adenocarcinomic epithelial cells (A549 cells). After 24h of treatment, IL-8 protein release from A549 cells, induced by 10, 50 and 250 microg/ml of P25 TiO2 NPs, were statistically significantly raised, compared to that of the control. This finding corroborates existing literature in that TiO2 NPs induce a dose-dependent increase in the release of IL-8 protein when exposed to A549 cells. However, the binding of NF-kappaB DNA was not affected after 6 h of incubation with P25. Therefore, NF-kappaB DNA binding is not the likely transcription pathway that leads to TiO2-induced inflammation.

Abstract 5005: Combined targeting of IKKα and β effectively suppresses NF-κB activation, cell survival and migration in head and neck squamous cell cancers

Abstract Activation of the transcription factor NF-kappaB (NF-kB) has been found to be a key promoter of tumorigenesis and a contributor of chemotherapy resistance in many cancers, including head and neck squamous cell carcinomas (HNSCC). The NK-kB pathway is regulated through both canonical and noncanonical pathways involving the IkB kinases (IKK) α and β which together, have been implicated in cancer pathogenesis. However, the individual roles of the IKK subunits have not been previously elucidated and potential therapeutic targets still largely remain to be characterized. Endogenous IKKα and β expression and phosphorylation were analyzed by IHC staining and western blot in HNSCC tumor specimens and cell lines (UM-SCC 11A and 11B). Individual and dual overexpression and knockdown of IKKα and β were assessed for their effects on NF-kB activation by a luciferase reporter assay, and on tumor cell proliferation and migration in vitro via MTT and wound healing assays, respectively. HNSCC tissue and cell lines exhibited aberrant expression with increased nuclear localization and phosphorylation of IKKα and β when compared to normal controls. In a panel of 9 HNSCC cell lines, endogenous IKKα was more abundantly expressed than IKKβ. While individual overexpression of wt or constitutively activated IKKβ was more potent than IKKα, dual overexpression of IKKα and β exhibited the strongest induction of NF-kB activation. siRNA knockdown of either kinase resulted in decreased cell proliferation and migration and NF-kB activation, and a combinatorial effect was seen with double IKKα and β knockdown. Additionally, chemical inhibitors targeting IKKα and β were used to evaluate their potential for suppressing NF-kB activation and targeting the HNSCC malignant phenotype in vitro. Four small molecule inhibitors were studied that preferentially targeted IKKα>β (17-DMAG), IKKβ (MLN120b and SC514), or both IKKα and β (wedelolactone). Compared to the IKKβ specific inhibitor, MLN120b, 17-DMAG more potently inhibited NF-kB DNA binding in electromobility shift assays (EMSA) and NF-kB reporter gene activation. MTT proliferation assays and flow cytometric DNA cell cycle analysis demonstrated more potent effects of 17-DMAG and wedelolactone in inhibiting cell proliferation. We conclude that overexpression and signaling mediated by both IKKα and β contribute to NF-kB activation, and pathogenesis of proliferation and migration of HNSCC cells in vitro. Furthermore, dual siRNA silencing or chemical inhibition of IKKα and β kinases resulted in combinatorial inhibitory effects on NF-kB activation and the malignant phenotype. In the face of intrinsic and acquired chemoresistance limiting treatment options, IKKα/β represent promising novel therapeutic targets for fighting HNSCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5005. doi:10.1158/1538-7445.AM2011-5005

Hypoxia-Inducible Factor 1α Determines Gastric Cancer Chemosensitivity via Modulation of p53 and NF-κB

BackgroundReduced chemosensitivity of solid cancer cells represents a pivotal obstacle in clinical oncology. Hence, the molecular characterization of pathways regulating chemosensitivity is a central prerequisite to improve cancer therapy. The hypoxia-inducible factor HIF-1α has been linked to chemosensitivity while the underlying molecular mechanisms remain largely elusive. Therefore, we comprehensively analysed HIF-1α's role in determining chemosensitivity focussing on responsible molecular pathways.Methodology and Principal FindingsRNA interference was applied to inactivate HIF-1α or p53 in the human gastric cancer cell lines AGS and MKN28. The chemotherapeutic agents 5-fluorouracil and cisplatin were used and chemosensitivity was assessed by cell proliferation assays as well as determination of cell cycle distribution and apoptosis. Expression of p53 and p53 target proteins was analyzed by western blot. NF-κB activity was characterized by means of electrophoretic mobility shift assay. Inactivation of HIF-1α in gastric cancer cells resulted in robust elevation of chemosensitivity. Accordingly, HIF-1α-competent cells displayed a significant reduction of chemotherapy-induced senescence and apoptosis. Remarkably, this phenotype was completely absent in p53 mutant cells while inactivation of p53 per se did not affect chemosensitivity. HIF-1α markedly suppressed chemotherapy-induced activation of p53 and p21 as well as the retinoblastoma protein, eventually resulting in cell cycle arrest. Reduced formation of reactive oxygen species in HIF-1α-competent cells was identified as the molecular mechanism of HIF-1α-mediated inhibition of p53. Furthermore, loss of HIF-1α abrogated, in a p53-dependent manner, chemotherapy-induced DNA-binding of NF-κB and expression of anti-apoptotic NF-κB target genes. Accordingly, reconstitution of the NF-κB subunit p65 reversed the increased chemosensitivity of HIF-1α-deficient cells.Conclusion and SignificanceIn summary, we identified HIF-1α as a potent regulator of p53 and NF-κB activity under conditions of genotoxic stress. We conclude that p53 mutations in human tumors hold the potential to confound the efficacy of HIF-1-inhibitors in cancer therapy.

Fenofibrate induces effective apoptosis in mantle cell lymphoma by inhibiting the TNFα/NF-κB signaling axis

Mantle cell lymphoma (MCL) is a type of aggressive B-cell non-Hodgkin's lymphoma characterized by frequent resistance to conventional chemotherapy. In this study we provided evidence that fenofibrate, which is widely known as an agonist for peroxisome proliferator-activated receptor-alpha (PPARalpha), can induce effective apoptosis in treating MCL cells. Addition of fenofibrate to MCL cell lines significantly decreased the number of viable cells by 50% at approximately 20 microM at 72 h. This decrease in cell growth was due to apoptosis, as evidenced by the cleavage of caspase 3 and poly(ADP-ribose) polymerase. The fenofibrate-mediated effects were not significantly affected by GW6471, a specific PPARalpha antagonist. Using an apoptosis pathway-specific oligonucleotide array, we found that fenofibrate significantly downregulated several pro-survival genes, including tumor necrosis factor-alpha (TNFalpha). Importantly, addition of recombinant TNF-alpha conferred partial protection against fenofibrate-induced apoptosis. Fenofibrate also decreased the nuclear translocation of nuclear factor (NF)-kappaB-p65 and significantly inhibited the DNA binding of NF-kappaB in a dose-dependent manner. To conclude, fenofibrate shows efficacy against MCL, and the mechanism can be attributed to its inhibitory effects on the TNF-alpha/NF-kappaB signaling axis. In view of the documented safety of fenofibrate in humans, it may provide a valuable therapeutic option for MCL patients.

A Novel Fluid Resuscitation Strategy Modulates Pulmonary Transcription Factor Activation in a Murine Model of Hemorrhagic Shock

INTRODUCTION:Combining the hemodynamic and immune benefits of hypertonic saline with the anti-inflammatory effects of the phosphodiesterase inhibitor pentoxifylline (HSPTX) as a hemorrhagic shock resuscitation strategy reduces lung injury when compared with the effects of Ringer’s lactate (RL). We hypothesized that HSPTX exerts its anti-inflammatory effects by interfering with nuclear factor kappa B/cAMP response element-binding protein (NF-κB-CREB) competition for the coactivator CREB-binding protein (CBP) in lung tissue, thus affecting pro-inflammatory mediator production.METHODS:Male Sprague-Dawley rats underwent 60 minutes of hemorrhagic shock to reach a mean arterial blood pressure of 35 mmHg followed by resuscitation with either RL or HSPTX (7.5% HS + 25 mg/kg PTX). After four hours, lung samples were collected. NF-κB activation was assessed by measuring the levels of phosphorylated cytoplasmic inhibitor of kappa B (I-κB) and nuclear NF-κB p65 by western blot. NF-κB and CREB DNA-binding activity were measured by electrophoretic mobility shift assay (EMSA). Competition between NF-κB and CREB for the coactivator CBP was determined by immunoprecipitation. Interleukin-8 (IL-8) levels in the lung were measured by ELISA.RESULTS:RL resuscitation produced significantly higher levels of lung IL-8 levels, I-κB phosphorylation, p65 phosphorylation, and NF-κB DNA binding compared with HSPTX. NF-κB-CBP-binding activity was similar in both groups, whereas CREB-CBP-binding activity was significantly increased with HSPTX. CREB-DNA binding-activity increased to a greater level with HSPTX compared with RL.DISCUSSION:HSPTX decreases lung inflammation following hemorrhagic shock compared with conventional resuscitation using RL through attenuation of NF-κB signaling and increased CREB-DNA binding activity. HSPTX may have therapeutic potential in the attenuation of ischemia-reperfusion injury observed after severe hemorrhagic shock.

Anti–citrullinated protein antibodies bind surface‐expressed citrullinated Grp78 on monocyte/macrophages and stimulate tumor necrosis factor α production

Anti-citrullinated protein antibodies (ACPAs), which are the most specific autoantibody marker in patients with rheumatoid arthritis (RA), correlate with disease activity; however, the role of ACPAs in RA pathogenesis has not been elucidated. We hypothesized that ACPAs may directly stimulate mononuclear cells to produce inflammatory cytokines. Thus, we identified cognate antigens of ACPAs on monocyte/macrophages and examined their immunopathologic roles in the pathogenesis of RA. ACPAs were purified from pooled ACPA-positive RA sera by cyclic citrullinated peptide-conjugated affinity column. After coculture of U937 cells with ACPAs, the tumor necrosis factor alpha (TNFalpha) production and NF-kappaB DNA binding activity of the cells were measured by enzyme-linked immunosorbent assay. The cognate antigens of ACPAs on the U937 cell surface were probed by ACPAs, and the reactive bands were examined via proteomic analysis. ACPAs specifically enhanced TNFalpha production and increased the DNA-binding activity of NF-kappaB in U937 cells. Proteomic analysis revealed that Grp78 protein (72 kd) was one of the cognate antigens of ACPAs. The truncated form of cell surface-expressed Grp78 (55 kd) on U937 cells contained citrulline capable of binding with ACPAs. After citrullination, glutathione S-transferase-tagged recombinant Grp78 (97.52 kd) became a 72-kd fragment and bound with ACPAs. ACPAs also bound to human monocytes and lymphocytes to promote TNFalpha production. We clearly demonstrated that ACPAs enhance NF-kappaB activity and TNFalpha production in monocyte/macrophages via binding to surface-expressed citrullinated Grp78.

Abstract LB-168: Genistein sensitizes radio-resistant cancer cells through regulation of NF-kappaB

Abstract Background: NF-kappaB is a key transcription factor involved in the control of normal cellular and organismal processes, such as immune and inflammatory responses, developmental processes, cellular growth, and apoptosis. However, NF-kappaB is persistently active in a number of disease states, including cancer. It has been reported that chemo- or radio- resistant cancer cells had elevated NF-kappaB activity. Recent studies including ours have showed that genistein, a soy-derived isoflavonoid, has antitumor activity in various cancer cells. Objective: In this study, we evaluated whether genistein could sensitize ionizing radiation resistance of cervical cancer cells through regulation of NF-kappaB. Methods: Six cervical cancer cell lines (HeLa, CaSki, C33A, ME180, SiHa, HeLa229) were treated by 20 Gy radiation with 50 M genistein or not. Cell growth rate was measured by MTT assay and protein expression level was analyzed by western blotting. Protein localization was observed by confocal microscopic analysis. NF-kappaB transcriptional activity was measured by luciferase reporter gene assay. NF-kappaB DNA binding activity was evaluated by electophoretic mobility shift assay. Results: Among six cervical cancer cells, HeLa and HeLa229 cells showed radio-resistance accompanied by elevated NF-kappaB activity. Ionizing radiation induced NF-kappaB nuclear transclocation and stimulated NF-kappaB DNA binding and transcriptional activities. However, pretreatment with genistein inhibited radiation induced transcriptional activity coincident to decreased radio-resistancy. Genistein also inhibited radiation-induced NF-kappaB regulated anti-apoptotic gene expression including c-myc, Survivin, XIAP, Bcl-2, IAP-1, TRAF, A1/Bfl-1 and FLIP. Conclusion: Taken together, genistein can sensitize radio-resistant cancer cells through regulation of NF-kappaB and could be used as a radio-sensitizer for the treatment of cervical cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-168.

Abstract 550: Transcriptional regulation of the Fanconi Anemia/BRCA DNA repair pathway component FANCD2 following co-culture of bone marrow stroma with multiple myeloma cell lines

Abstract MM is an incurable B cell malignancy characterized by the acquisition of drug resistance. To this end, we have recently demonstrated that selected resistance to the melphalan correlated with a RelB/p50 mediated transactivation of FANCD2 in the 8226 LR5 MM cell line.(Oliveira et al. Cancer Res 2009) These results demonstrated a causal relationship between RelB/p50 transactivation of FANCD2, increased DNA repair, and acquired resistance to melphalan. Although numerous genetic alterations have been implicated in acquired MDR in MM, the bone marrow (BM) microenvironment has also been demonstrated to contribute to drug resistance-or environment-mediated drug resistance (EM-DR). Therefore, utilizing the HS-5 bone marrow stromal (BMS) cell line as a model of the EM-DR, we wished determine if co-culture with RPMI 8226 or 8226/LR5 affected expression of FA/BRCA DNA repair pathway components. Examination of drug sensitive, drug resistant MM, and stromal cell lines demonstrated differential enhancement of FA/BRCA DNA repair pathway protein expression. These preliminary results demonstrate that expression of FA/BRCA pathway components is regulated by cellular interactions in both MM cells and BMSC suggesting that juxtaposed bone marrow stroma influences FA/BRCA-mediated DNA repair and drug resistance. We previously demonstrated RelB/p50 specific transcriptional regulation of FANCD2 in drug selected MM cells. Here, we demonstrate that co-culture of MM cell lines with BMSCs facilitates NF-kappaB DNA binding activity (0-6hr), suggesting a similar RelB/p50 mediated- transactivation of FANCD2. To further examine this we have stably transfected HS-5 cells with luciferase reporter constructs under the control of the FANCD2 promoter. Following co-culture with RPMI 8226 or 8226 LR5 increased FANCD2 promoter activity was noted at early time points (0.5-6hours), but was diminished by 24 hours. FANCD2 promoter activity correlates with protein expression in HS-5 cells incubated with either cell line (0-6hrs). However, in HS-5 cells co-cultured with RPMI 8226 cells FANCD2 protein levels were maintained even after promoter activity had subsided. These data illustrate a novel transcriptional control of FANCD2 in under co-culture conditions. Moreover, these findings suggest that the FA/BRCA mediated DNA damage repair may be an important component of EM-DR. However, continued investigation will be needed to determine the breadth of transcriptional (and/or alternate) regulation of FAND2 and other members of the FA family. Further, future studies will examine a causal relationship between increased FANC expression and melphalan (and other drug) resistance seen in co-culture conditions. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 550.

Abstract 3674: Inhibition of noncanonical NF-kappa B activation by (−)-DHMEQ in vitro and in adult T-cell leukemia cells

Abstract [Objective and Rationale]Noncanonical NF-kappa B consisting of RelB and p52 is especially important for the maturation of B-lymphocytes and autoimmune diseases. In one hand, we have designed and synthesized a novel NF-kappa B inhibitor (−)-DHMEQ. It showed potent anti-inflammatory and anti cancer effects in animal models without any toxicity. We have reported (−)-DHMEQ covalently binds to the specific Cys residue of each NF-kappa B component and that it inhibits the DNA binding of canonical NF-kappa B components. However, the effects on noncanonical NF-kappa B has not been studied at the molecular level. In the present research we have studied theinhibitory effect of (−)-DHMEQ on noncanonical NF-kappa B in vitro and in cultured lymphoma cells in which noncanonical NF-kappa B is constitutively activated. [Experimental Design and Results]We prepared recombinant noncanonical NF-kappa B proteins, RelB and p52. (−)-DHMEQ was shown to covalently bind to Cys144 of RelB but not to p52 in MLADI-TOF/MS and mutation analysis. Either RelB or p52 does not form homodimer. Then, we prepared HeLa cells over–expressing full length RelB and p52. (−)-DHMEQ inhibited the NF-kappa B activity in RelB(wild type)/p52 cells but not in RelB(C144S)/p52 expressing cells in EMSA. Thus (−)-DHMEQ was shown to target Cys 144 of RelB in cultured cells to inhibit noncanonical NF-kappa B-DNA binding. It also inhibited RelB/p52 binding to DNA in vitro. Then, we looked for the cell line in which noncanonical NF-kappa B is constitutively activated using anti-RelB in EMSA. MT-1 cells are HTLV-1 transformed T-cells and often used for the adult T-cell leukemia (ATL) model. We found that the highly activated NF-kappa B is mainly consisting with noncanonical one in MT-1 cells. (−)-DHMEQ effectively inhibited the noncanonical NF-kappa B activity in MT-1 cells. [Conclusion] (−)-DHMEQ binds to RelB and effectively inhibited RelB/p52-DNA binding. We have found noncanonical NF-kappa B is highly activated ATL-like MT-1 cells, which was inhibited by (−)-DHMEQ. (−)-DHMEQ may be useful for the treatment of ATL and other diseases induced by noncanonical NF-kappaB activation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3674.

CK2 Modulation of NF-κB, TP53, and the Malignant Phenotype in Head and Neck Cancer by Anti-CK2 OligonucleotidesIn vitroorIn vivovia Sub–50-nm Nanocapsules

The aim of this study is to investigate the expression of CK2 subunits and CK2 effects on NF-kappaB-mediated and TP53-mediated signal activation and gene expression, the malignant phenotype, and chemosensitivity in head and neck squamous cell carcinoma (HNSCC) in vitro and in vivo. Protein expression of CK2 subunits was investigated by Western blot and immunohistochemistry. CK2 subunits were knocked down by small interfering RNA, and NF-kappaB activation was examined using DNA binding, Western blot, and luciferase reporter assays. Gene expression was measured by quantitative reverse transcription-PCR. Cell growth, survival, motility, and sensitivity to cisplatin were measured by MTT, flow cytometry, and migration assays. In vivo targeting of CK2alpha/alpha' in HNSCC xenograft models was achieved using anti-CK2alpha/alpha' oligodeoxynucleotide encapsulated in sub-50-nm tenfibgen nanocapsules. CK2 subunit proteins were overexpressed in HNSCC lines and tissues. Knockdown of CK2 subunits differentially inhibited IkappaBalpha degradation, NF-kappaB nuclear localization, phosphorylation, DNA binding, and reporter activity. CK2 subunits modulated gene expression and the malignant phenotype involved in cell cycle and migration, whereas CK2alpha is critical to promote proliferation, antiapoptosis, and cisplatin resistance in vitro. Furthermore, in vivo delivery of anti-CK2alpha/alpha' oligodeoxynucleotide nanocapsules significantly suppressed tumor growth in HNSCC xenograft models, in association with modulation of CK2 and NF-kappaB regulated molecules, TP53 family proteins, and induction of apoptosis. Our study reveals a novel role of CK2 in coregulating NF-kappaB activation, TP53/p63 expression, and downstream gene expression. Downregulation of CK2 in HNSCC models in vitro and in vivo shows antitumor effects as well as sensitization to cisplatin.

Effect of Toll-like receptor 4 inhibitor on LPS-induced lung injury

Toll-like receptor 4 (TLR4) plays important roles in the recognition of lipopolysaccharide (LPS) and the activation of inflammatory cascade. In this study, we evaluated the effect of TAK-242, a selective TLR4 signal transduction inhibitor, on acute lung injury (ALI). C57BL/6J mice were intravenously treated with TAK-242 15 min before the intratracheal administration of LPS or Pam3CSK4, a synthetic lipopeptide. Six hours after the challenge, bronchoalveolar lavage fluid was obtained for a differential cell count and the measurement of cytokine and myeloperoxidase levels. Lung permeability and nuclear factor-kappaB (NF-kappaB) DNA binding activity were also evaluated. TAK-242 effectively attenuated the neutrophil accumulation and activation in the lungs, the increase in lung permeability, production of inflammatory mediators, and NF-kappaB DNA-binding activity induced by the LPS challenge. In contrast, TAK-242 did not suppress inflammatory changes induced by Pam3CSK4. TAK-242 may be a promising therapeutic agent for ALI, especially injuries associated with pneumonia caused by Gram-negative bacteria.

Critical Need for Clinical Trials: An Example of a Pilot Human Intervention Trial of a Mixture of Natural Agents Protecting Lymphocytes Against TNF-α Induced Activation of NF-κB

Humans typically consume "natural agents" that are believed to be chemoprotective and are known to decrease inflammation biomarker NF-kappaB in vitro; however, no intervention studies in humans have been done to date. This commentary documents the in vivo results as a powerful example for supporting the superiority of a complex mixture of natural agents. Human volunteers consumed two 500 mg capsules (BID) containing a mixture of natural agents for a period of 2 weeks, and blood samples were collected pre- and post-intervention. The purified lymphocytes were subjected to ex-vivo exposure to TNF-alpha or kept as untreated control. The mean NF-kappaB DNA binding activity was increased upon TNF-alpha treatment in pre-intervention samples; however, TNF-alpha was unable to induce NF-kappaB in post-intervention samples, suggesting that the mixture of four important natural agents could be useful to protect humans against oxidative stress.

Inhibiting TRAF2-mediated Activation of NF-κB Facilitates Induction of AP-1

The compound 5-(4-methoxyarylimino)-2-N-(3,4-dichlorophenyl)-3-oxo-1,2,4-thiadiazolidine (P(3)-25) is known to possess anti-bacterial, anti-fungal, and anti-tubercular activities. In this report, we provide evidence that P(3)-25 inhibits NF-kappaB, known to induce inflammatory and tumorigenic responses. It activates AP-1, another transcription factor. It inhibits TRAF2-mediated NF-kappaB activation but not TRAF6-mediated NF-kappaB DNA binding by preventing its association with TANK (TRAF for NF-kappaB). It facilitates binding of MEKK1 with TRAF2 and thereby activates JNK and AP-1. We provide evidence, for the first time, that suggests that the interaction of P(3)-25 with TRAF2 leads to inhibition of the NF-kappaB pathway and activation of AP-1 pathway. These results suggest novel approaches to design of P(3)-25 as an anti-cancer/inflammatory drug for therapy through regulation of the TRAF2 pathway.

Cilostazol is anti‐inflammatory in BV2 microglial cells by inactivating nuclear factor‐kappaB and inhibiting mitogen‐activated protein kinases

Cilostazol is a specific inhibitor of 3'-5'-cyclic adenosine monophosphate (cAMP) phosphodiesterase, which is widely used to treat ischemic symptoms of peripheral vascular disease. Although cilostazol has been shown to exhibit vasodilator properties as well as antiplatelet and anti-inflammatory effects, its cellular mechanism in microglia is unknown. In the present study, we assessed the anti-inflammatory effect of cilostazol on the production of pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated murine BV2 microglia. We examined the effects of cilostazol on LPS-induced nuclear factor-kappaB (NF-kappaB) activation and phosphorylation of mitogen-activated protein kinases (MAPKs). Cilostazol suppressed production of nitric oxide (NO), prostaglandin E(2) (PGE(2)) and the proinflammatory cytokines, interleukin-1 (IL-1), tumour necrosis factor-alpha, and monocyte chemoattractant protein-1 (MCP-1), in a concentration-dependent manner. Inhibitory effects of cilostazol were not affected by treatment with an adenylate cyclase inhibitor, SQ 22536, indicating that these actions of cilostazol were cAMP-independent. Cilostazol significantly inhibited the DNA binding and transcriptional activity of NF-kappaB. Moreover, cilostazol blocked signalling upstream of NF-kappaB activation by inhibiting extracellular signal-regulated kinases 1 and 2 (ERK1/2) and c-Jun N-terminal kinase (JNK), but without affecting the activity of p38 MAPK. Our results demonstrate that suppression of the NF-kappaB, ERK, JNK signalling pathways may inhibit LPS-induced NO and PGE(2) production. Therefore, cilostazol may have therapeutic potential for neurodegenerative diseases by inhibiting pro-inflammatory mediators and cytokine production in activated microglia.

Azadirachtin Interacts with the Tumor Necrosis Factor (TNF) Binding Domain of Its Receptors and Inhibits TNF-induced Biological Responses

The role of azadirachtin, an active component of a medicinal plant Neem (Azadirachta indica), on TNF-induced cell signaling in human cell lines was investigated. Azadirachtin blocks TNF-induced activation of nuclear factor kappaB (NF-kappaB) and also expression of NF-kappaB-dependent genes such as adhesion molecules and cyclooxygenase 2. Azadirachtin inhibits the inhibitory subunit of NF-kappaB (IkappaB alpha) phosphorylation and thereby its degradation and RelA (p65) nuclear translocation. It blocks IkappaB alpha kinase (IKK) activity ex vivo, but not in vitro. Surprisingly, azadirachtin blocks NF-kappaB DNA binding activity in transfected cells with TNF receptor-associated factor (TRAF)2, TNF receptor-associated death domain (TRADD), IKK, or p65, but not with TNFR, suggesting its effect is at the TNFR level. Azadirachtin blocks binding of TNF, but not IL-1, IL-4, IL-8, or TNF-related apoptosis-inducing ligand (TRAIL) with its respective receptors. Anti-TNFR antibody or TNF protects azadirachtin-mediated down-regulation of TNFRs. Further, in silico data suggest that azadirachtin strongly binds in the TNF binding site of TNFR. Overall, our data suggest that azadirachtin modulates cell surface TNFRs thereby decreasing TNF-induced biological responses. Thus, azadirachtin exerts an anti-inflammatory response by a novel pathway, which may be beneficial for anti-inflammatory therapy.

Preventive Effect of a Proteasome Inhibitor on the Formation of Accelerated Atherosclerosis in Rabbits With Uremia

Inflammation plays a central role in the pathogenesis of atherosclerosis. This study investigated whether the proteasome inhibitor has the same preventive effect on the formation of accelerated atherosclerosis in rabbits with uremia compared with a NF-kappaB inhibitor. New Zealand white rabbits were subjected to five-sixths nephrectomy (chronic renal failure [CRF]) or to a sham operation. Rats in each group were randomly assigned into three subgroups (n = 24 in each group) and treated with repeated intramuscular injections of proteasome inhibitor MG132 or NF-kappaB inhibitor PDTC for a specified period. Compared with sham rabbits, CRF rabbits displayed typical atherosclerotic changes (endothelial cell damage, intimal thickens, and appearance of foam cells). CRF rabbits had significantly higher levels of proteasome activity, NF-kappaB mRNA, protein, and DNA binding activity as well as tumor necrosis factor-a and proliferative cell nuclear antigen protein expression in aortic wall cells. CRF rabbits also showed lower levels of IkappaBalpha. Compared with CRF rabbits, CRF rabbits treatment with proteasome inhibitor MG132 showed restoration of IkappaBalpha mRNA and protein expression and decreased NF-kappaB DNA binding activity and tumor necrosis factor-a expression. Treatment with either proteasome inhibitor MG132 or NF-kappaB inhibitor PDTC could reverse these pathologic changes in the aortic wall cells of CRF rabbits. A comparison between the inhibitory effects of the two treatments revealed no statistical difference. These results suggest that ubiquitin-proteasome activation play a pivotal role in the pathogenesis of uremia-accelerated atherosclerosis. The ubiquitin-proteasome signaling pathway in aortic cells may therefore be an important target for preventing uremia-accelerated atherosclerosis.

High‐throughput detection of nuclear factor‐kappaB activity using a sensitive oligo‐based chemiluminescent enzyme‐linked immunosorbent assay

Contemporary research on cellular signaling has undergone a shift of focus from qualitative measurements of single signaling pathways to high-throughput quantitation of comprehensive signaling networks. Notably, nuclear factor-kappaB (NFkappaB) is a family of transcription factors involved in immune and inflammatory responses, developmental processes, cellular growth and apoptosis and is deregulated in a number of disease states. We have established a chemiluminescent oligonucleotide-based enzyme-linked immunosorbent assay (co-ELISA) that is simple and quantitative. In contrast to currently used assays, it allows quantitation of all NFkappaB components (i.e., RelA, p50, p52, RelB and c-Rel). In addition, it can make use of whole extract and does not require cumbersome nuclear/cytosolic fractionation, saving time and resources. Co-ELISA has a 3.5- to 43-fold higher signal-over-noise ratio than currently available assays, whereas the percent relative standard deviation is 3- to 6-fold lower. Furthermore, the novel method is faster than electrophoretic mobility shift assay, not restricted to transfectable cells as is the case for luciferase reporter assays and 10 times more cost efficient than commercially available ELISA assays. Co-ELISA is a sensitive, fast and cost-efficient quantitation method for all DNA-binding NFkappaB proteins that can be used in high-throughput experimentation.

Inhibition of Inflammatory Cytokine Production from Rheumatoid Synovial Fibroblasts by a Novel IκB Kinase Inhibitor

Nuclear factor-kappaB (NF-kappaB) is involved in the pathophysiology of rheumatoid arthritis (RA) and is considered to be a feasible molecular target in treating patients. In the RA joint tissues, activation of NF-kappaB is often observed together with high amounts of the proinflammatory cytokines tumor necrosis factor (TNF)alpha and interleukin (IL)-1beta. TNFalpha and IL-1beta are known to stimulate NF-kappaB signaling and are produced as the effect of NF-kappaB signaling, thus forming a vicious cycle leading to a self-perpetuating nature of rheumatoid inflammation and expansion of such inflammatory response to other joints. Because a kinase called IkappaB kinase complex (IKK) is involved in the NF-kappaB activation cascade, we examined the effect of a novel IKK inhibitor, (7-[2-(cyclopropyl-methoxy)-6-hydroxyphenyl]-5-[(3S)-3-piperidinyl]-1,4-dihydro-2H-pyrido[2,3-d][1,3]oxazin-2-one hydrochloride; CHPD), on the production of inflammatory cytokines from rheumatoid synovial fibroblasts (RSF). TNFalpha stimulation induced production of inflammatory cytokines such as IL-6 and IL-8 in RSF, and the extent of IL-6 and IL-8 induction was dramatically reduced by CHPD under noncytotoxic concentrations. Likewise, expression of il-6 and il-8 genes was significantly reduced by CHPD. In addition, chromatin immunoprecipitation assays revealed that the DNA binding of NF-kappaB (p65) to il-8 promoter in RSF was induced after TNFalpha stimulation and that, upon CHPD treatment to RSF for 1 h, the NF-kappaB binding to il-8 promoter was significantly decreased. Here, we have demonstrated that an IKKbeta inhibitor, CHPD, acts as an effective inhibitor for the production of inflammatory cytokines in response to proinflammatory cytokines. These findings indicate that such a IKKbeta inhibitor could be a feasible candidate for an antirheumatic drug.

Dynamic and Selective Nucleosome Repositioning during Endotoxin Tolerance

Sepsis is encoded by a sequel of transcription activation and repression events that initiate, sustain, and resolve severe systemic inflammation. The repression/silencing phase occurs in blood leukocytes of animals and humans following the initiation of systemic inflammation due to developing endotoxin tolerance. We previously reported that NF-kappaB transcription factor RelB and histone H3 lysine methyltransferase G9a directly interact to induce facultative heterochromatin assembly and regulate epigenetic silencing during endotoxin tolerance, which is a major feature of sepsis. The general objective of this study was to assess whether dynamic temporal, structural, and positional changes of nucleosomes influence the sepsis phenotype. We used the THP-1 sepsis cell model to isolate mononucleosomes by rapid cell permeabilization and digestion of chromatin with micrococcal nuclease and then compared tumor necrosis factor alpha (TNFalpha) proximal promoter nucleosome alignment in endotoxin-responsive and -tolerant phenotypes. We found differential and dynamic repositioning of nucleosomes from permissive to repressive locations during the activation and silencing phases of transcription reprogramming and identified the following mechanisms that may participate in the process. 1) Two proximal nucleosomes repositioned to expose the primary NF-kappaB DNA binding site in endotoxin-responsive cells, and this "promoter opening" required the ATP-independent chaperone NAP1 to replace the core histone H2A with the H2A.Z variant. 2) During RelB-dependent endotoxin tolerance, the two nucleosomes repositioned and masked the primary NF-kappaB DNA binding site. 3) Small interfering RNA-mediated inhibition of RelB expression prevented repressive nucleosome repositioning and tolerance induction, but the "open" promoter required endotoxin-induced NF-kappaB p65 promoter binding to initiate transcription, supporting the known requirement of p65 posttranslational modifications for transactivation. 4) Sustaining the permissive promoter state after RelB knockdown required ATP-dependent nucleosome remodeler BAF complex. Moreover, we found that forced expression of RelB in responsive cells induced repressive nucleosome positioning and silenced TNFalpha transcription, demonstrating the plasticity of nucleosome remodeling and its dependence on RelB. Our data suggest that nucleosome repositioning controls both the induction and epigenetic silencing phases of TNFalpha transcription associated with sepsis.

Inhibition of NF‐κB signaling by fasudil as a potential therapeutic strategy for rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common systemic autoimmune disease and is characterized mainly by symmetric polyarticular joint disorders. The pathologic processes are mediated by a number of cytokines, chemokines, cell adhesion molecules, and matrix metalloproteinases. The expression of most of these molecules is controlled at the transcriptional level. In addition, activation of NF-kappaB is involved in RA pathogenesis. This study was performed to explore the role of a novel serine/threonine kinase inhibitor, fasudil, in the control of the NF-kappaB activation pathway and to investigate the therapeutic effects of fasudil on arthritis development in a rat model of RA. Fibroblast-like synoviocytes (FLS) from RA patients and human endothelial cells (ECs) were established and maintained. To study the role of fasudil on cytokine expression, various cytokines expressed in the RA FLS and human ECs were measured by enzyme-linked immunosorbent assay following stimulation of the cells with interleukin-1beta (IL-1beta) in the presence of various concentrations of fasudil. The role of fasudil on NF-kappaB activation was studied using a reporter gene assay, Western blotting of IkappaBalpha, immunofluorescence analysis of the p65 subunit of NF-kappaB, and electrophoretic mobility shift assay. The in vivo effects of fasudil on arthritis were studied in a rat adjuvant-induced arthritis (AIA) model. Fasudil inhibited cytokine expression in RA FLS and human ECs and also inhibited the activation of ECs, in a dose-dependent manner. Fasudil inhibited IL-1beta-induced activation of NF-kappaB independent of the inhibition of IkappaBalpha degradation and nuclear translocation of NF-kappaB, and inhibited IL-1beta-induced DNA binding of NF-kappaB. Finally, in vivo, fasudil ameliorated arthritis in rats with AIA, without any adverse effects. Serine/threonine kinase inhibitor fasudil inhibits the development of arthritis in a rat model of RA, and also inhibits the NF-kappaB signaling required for binding of NF-kappaB to specific DNA sequences through, for example, the phosphorylation of p65, suggesting that a specific target of fasudil might be a novel NF-kappaB kinase. Thus, fasudil serves as a novel strategy for the treatment of RA.