TNF a Humain (A61681)

Loss of WASF3 function in breast cancer cells results in loss of invasion phenotypes and reduced metastatic potential. By using oligonucleotide arrays, we now demonstrate that knockdown of WASF3 leads to the upregulation of the KISS1 metastasis suppressor gene with concomitant reduced invasion and loss of matrix metalloproteinases (MMP)-9 activity. Using a luciferase reporter, KISS1 transcription is significantly increased in the absence of WASF3. Knockdown of KISS1 in WASF3-silenced cells resulted in the recovery of the invasion phenotype. WASF3 knockdown also resulted in elevated IκBα levels in the cytoplasm and reduced levels of nuclear factor-kappa-B (NF-κB) p65/50 subunits in the nucleus. Tumor necrosis factor-alpha (TNF-α) has been associated with cell invasion through induction of MMP-9 production via KISS1 regulation of the NF-κB pathway. When WASF3 knockdown cells are treated with TNF-α, no effect is seen on invasion or nuclear translocation of NF-κB. Thus, coordinated expression patterns of the WASF3 metastasis promoter gene and the KISS1 metastasis suppressor gene appear to exert their influence through inhibition of NF-κB signaling, which in turn regulates MMP-9 production facilitating invasion.

Induced radioresistance in the surviving cancer cells after radiotherapy could be associated with clonal selection leading to tumor regrowth at the treatment site. Previously we reported that post-translational modification of IκBα activates NFκB in response to ionizing radiation (IR) and plays a key role in regulating apoptotic signaling. Herein, we investigated the orchestration of NFκB after IR in human neuroblastoma. Both in vitro (SH-SY5Y, SK-N-MC, and IMR-32) and in vivo (xenograft) studies showed that IR persistently induced NFκB DNA binding activity and NFκB-dependent TNFα transactivation and secretion. Approaches including silencing NFκB transcription, blocking post-translational NFκB nuclear import, muting TNF receptor, overexpression, and physiological induction of either NFκB or TNFα precisely demonstrated the initiation and occurrence of NFκB → TNFα → NFκB positive feedback cycle after IR that leads to and sustains NFκB activation. Selective TNF-dependent NFκB regulation was confirmed with futile inhibition of AP-1 and SP-1 in TNF receptor muted cells. Moreover, IR increased both transactivation and translation of Birc1, Birc2, and Birc5 and induced metabolic activity and clonal expansion. This pathway was further defined to show that IR-induced functional p65 transcription (not NFκB1, NFκB2, or c-Rel) is necessary for activation of these survival molecules and associated survival advantage. Together, these results demonstrate for the first time the functional orchestration of NFκB in response to IR and further imply that p65-dependent survival advantage and initiation of clonal expansion may correlate with an unfavorable prognosis of human neuroblastoma.

TNFα, a proinflammatory cytokine known to be involved in the pathogenesis of allergic asthma, has been shown to induce hyperalgesia in somatic tissue via a sensitizing effect on dorsal root ganglion neurons expressing transient receptor potential vanilloid type 1 receptor (TRPV1). Because TRPV1-expressing pulmonary sensory neurons play an important role in regulating airway function, this study was carried out to determine whether TNFα alters the sensitivity of these neurons to chemical activators. Responses of isolated nodose and jugular ganglion neurons innervating the rat lungs were determined by measuring the transient increase in intracellular Ca(2+) concentration ([Ca(2+)](i)). Our results showed the following. 1) A pretreatment with TNFα (50 ng/ml) for ∼24 h increased significantly the peak Δ[Ca(2+)](i) evoked by capsaicin (Cap) in these neurons. A pretreatment with the same concentration of TNFα for a longer duration (∼48 h) did not further increase the response, but pretreatment for a shorter duration (1 h) or with a lower concentration (25 ng/ml, 24 h) failed to enhance the Cap sensitivity. 2) The same TNFα pretreatment also induced similar but less pronounced and less uniform increases in the responses to acid (pH 6.5-5.5), 2-aminoethoxydiphenyl borate (2-APB), a common activator of TRPV1, V2, and V3 channels, and allyl isothiocyanate (AITC), a selective activator of TRPA1 channel. 3) In sharp contrast, the responses to ATP, ACh, and KCl were not affected by TNFα. 4) The TNFα-induced hypersensitivity to Cap was not prevented by pretreatment with indomethacin (30 μM). 5) The immunoreactivity to both TNF receptor types 1 and 2 were detected in rat vagal pulmonary sensory neurons. In conclusion, prolonged treatment with TNFα induces a pronounced potentiating effect on the responses of isolated pulmonary sensory neurons to TRPV1 activators. This action of TNFα may contribute in part to the airway hyperresponsiveness induced by this cytokine.

Rifampin increased nitric oxide production and inducible nitric oxide synthase expression in alveolar cells stimulated with cytokines. Nitric oxide concentrations after induction with cytokines, cytokines with 10 microg/ml rifampin, and cytokines with 50 microg/ml rifampin were 3.2, 4.5, and 8.8 microM, respectively (P < 0.02 versus cytokines alone). This indicates that rifampin modulates the immune response.

We have previously demonstrated that pretreatment of mice with Shigella dysenteriae sonicate enhanced their susceptibility to pentylenetetrazole-induced seizures and that tumor necrosis factor alpha (TNF-alpha) was proconvulsive in this respect. The present study shows that TNF-alpha, at high concentrations, may also exert a suppressive effect on Shigella-mediated seizures. This implies that high levels of TNF-alpha may play a protective role in neurologic complications of S. dysenteriae infection.

Type I interferons (IFNs) are known to cause neuropsychiatric side effects, which have been proposed to be mediated by either peripheral actions or activation of glial cells. In the present study, we have investigated whether these cytokines could act directly on neuronal cells and regulate signaling pathways involved in cell death. In human SH-SY5Y neuroblastoma cells, type I IFNs rapidly stimulated tyrosine phosphorylation of Janus kinase and signal transducer and activator of transcription (STAT) through type I IFN receptor. Prolonged exposure to IFN-β induced apoptotic cell death accompanied by cytochrome C release, cleavage of caspases 9, 7, 3 and poly-(ADP ribose) polymerase and DNA fragmentation. Janus kinase inhibition reduced IFN-β-stimulated TyK2 and STAT1 phosphorylation, STAT1 transcriptional activity, induction of double-stranded RNA-activated protein kinase (PKR) and caspase cleavage. PKR induction was associated with enhanced PKR activity and chemical inhibition of PKR reduced IFN-stimulated caspase activation. Moreover, long-term IFN-β treatment led to down-regulation of phosphatidylinositol 3-kinase/Akt signaling and IFN-β-induced apoptosis was attenuated in cells expressing constitutively active Akt. Similarly, in mouse primary neurons IFN-β induced STAT phosphorylation, caspase 3 cleavage and inhibition of Akt signaling. Thus, type I IFNs can directly impair neuronal survival by regulating multiple signaling molecules promoting the intrinsic apoptotic pathway. This effect may contribute to the cytokine neurotoxicity.

Cocoa polyphenols have antioxidant and anti-inflammatory effects. TNF-α is a pro-inflammatory cytokine that has a vital role in the pathogenesis of inflammatory diseases such as cancer and psoriasis. Vascular endothelial growth factor (VEGF) expression is associated with tumorigenesis, CVD, rheumatoid arthritis and psoriasis. We tested whether cocoa polyphenol extract (CPE) inhibited TNF-α-induced VEGF expression in promotion-sensitive JB6 mouse epidermal cells. CPE significantly inhibited TNF-α-induced up-regulation of VEGF via reducing TNF-α-induced activation of the nuclear transcription factors activator protein-1 (AP-1) and NF-κB, which are key regulators of VEGF expression. CPE also inhibited TNF-α-induced phosphorylation of protein kinase B (Akt) and extracellular signal-regulated kinase. CPE blocked activation of their downstream kinases, p70 kDa ribosomal protein S6 kinase and p90 kDa ribosomal protein S6 kinase. CPE suppressed phosphoinositide 3-kinase (PI3K) activity via binding PI3K directly. CPE did not affect TNF-α-induced phosphorylation of mitogen-activated protein kinase kinase-1 (MEK1) but suppressed TNF-α-induced MEK1 activity. Collectively, these results indicate that CPE reduced TNF-α-induced up-regulation of VEGF by directly inhibiting PI3K and MEK1 activities, which may contribute to its chemopreventive potential.

Progression of hematologic malignancies is strongly dependent on bidirectional interactions between tumor cells and stromal cells. Expression of members of the matrix metalloproteinase (MMP) family by stromal cells is a central event during these interactions. However, although several studies have focused on the mechanisms responsible for induction of MMP in stromal cells, the signals that negatively regulate their secretion of in these cells remain largely unknown. Here, we provide evidence that MMP-9 production by stromal cells is suppressed through activation of early growth response protein 1 (EGR-1), thereby inhibiting the growth of thymic lymphoma. We found that EGR-1 expression is induced in stromal cells after contact with lymphoma cells via epidermal growth factor (EGF). Moreover, development of thymic lymphoma was inhibited when induced by lymphoma cells overexpressing EGF compared with control lymphoma cells. Using transgenic mice containing MMP-9 promoter-driven luciferase transgene in its genome, we further demonstrated that EGF/EGR-1 repressed transcriptional activation of the MMP-9 gene by stromal cells. De novo expression of EGR-1 alone by gene transfer or exposure to recombinant human EGF also inhibited MMP-9 expression. Taken together, these results indicate that EGR-1 could be a source of novel targets for therapeutic intervention in lymphoid tumors in which MMP-9 plays a critical role.

The traditional Chinese medicinal mushroom, Ganoderma lucidum, has been used in Asia for several thousand years for the prevention and treatment of a variety of diseases, including cancer. In previous work, we purified ganoderic acid T (GA-T) from G. lucidum [28]. In the present study, we investigate the functions of GA-T in terms of its effects on invasion in vitro and metastasis in vivo. A trypan blue dye exclusion assay indicates that GA-T inhibits proliferation of HCT-116 cells, a human colon carcinoma cell line. Cell aggregation and adhesion assays show that GA-T promotes homotypic aggregation and simultaneously inhibits the adhesion of HCT-116 cells to the extracellular matrix (ECM) in a dose-dependent manner.Wound healing assays indicate that GA-T also inhibits the migration of HCT-116 cells in a dose-dependent manner, and it suppresses the migration of 95-D cells, a highly metastatic human lung tumor cell line, in a dose- and time-dependent manner. In addition, GA-T inhibits the nuclear translocation of nuclear factor-kappaB (NF-kappaB) and the degradation of inhibitor of kappaB-alpha (IkappaBalpha), which leads to down-regulated expression of matrix metalloproteinase-9 (MMP-9), inducible nitric oxide synthase (iNOS), and urokinase-type plasminogen activator (uPA). Animal and Lewis Lung Carcinoma (LLC) model experiments demonstrate that GA-T suppresses tumor growth and LLC metastasis and down-regulates MMP-2 and MMP-9 mRNA expression in vivo. Taken together, these results demonstrate that GA-T effectively inhibits cancer cell invasion in vitro and metastasis in vivo, and thus it may act as a potential drug for treating cancer.

Intracellular binding proteins can be applied as research tools for target validation and study of protein function in cells and potentially as therapeutics. The success of intracellular binding reagents depends on their affinity and specificity for target molecules, although their stability and functionality in the intracellular environment actually determine their usefulness for such application. Alternative binding proteins derived from scaffolds devoid of disulfide bonds are well suited for intracellular use, as their folding and stability are usually not impaired under reducing conditions. Here, we describe the generation of intracellular binding reagents called Affilin, based on the human gammaB-crystallin scaffold. The target was human papillomavirus E7 protein implicated in the development of cervical cancer. E7 binders were selected from the combinatorial gammaB-crystallin library by conventional phage display technique. Affilin variants specifically bound the E7 protein with affinities in the nanomolar range. Intracellular expression of Affilin molecules in E7-positive cells led to inhibition of cellular proliferation. The effect was specific, as the growth of E7-negative cells or cells expressing the wild-type gammaB-crystallin scaffold remained unaffected. These results demonstrate that the gammaB-crystallin scaffold allows the de novo generation of alternative binding proteins, which are suitable for intracellular applications as they retain their functionality in the reducing environment of mammalian cells.

Here we describe the first reported use of a Gram-positive bacterial system for the selection of affinity proteins from large combinatorial libraries displayed on the surface of Staphylococcus carnosus. An affibody library of 3 x 10(9) variants, based on a 58 residue domain from staphylococcal protein A, was pre-enriched for binding to human tumor necrosis factor-alpha (TNF-alpha) using one cycle of phage display and thereafter transferred to the staphylococcal host ( approximately 10(6) variants). The staphylococcal-displayed library was subjected to three rounds of flow-cytometric sorting, and the selected clones were screened and ranked by on-cell analysis for binding to TNF-alpha and further characterized using biosensor analysis and circular dichroism spectroscopy. The successful sorting yielded three different high-affinity binders (ranging from 95 pM to 2.2 nM) and constitutes the first selection of a novel affinity protein using Gram-positive bacterial display. The method combines the simplicity of working with a bacterial host with the advantages of displaying recombinant proteins on robust Gram-positive bacteria as well as using powerful flow cytometry in the selection and characterization process.

The current study was conducted to elucidate the mechanism through which TNF-alpha stimulates expression of MUC1, a membrane-tethered mucin. A549 human lung alveolar cells treated with TNF-alpha exhibited significantly higher MUC1 protein levels in detergent lysates compared with cells treated with vehicle alone. Increased MUC1 protein levels were correlated with significantly higher levels of MUC1 mRNA in TNF-alpha-treated cells compared with controls. However, TNF-alpha did not alter MUC1 transcript stability, implying increased de novo transcription induced by the cytokine. TNF-alpha increased MUC1 gene promoter activity in A549 cells transfected with a promoter-luciferase reporter plasmid. Both U0126, an inhibitor of MEK1/2, and dominant negative ERK1 prevented TNF-alpha-induced MUC1 promoter activation, and anti-TNFR1 antibody blocked TNF-alpha-stimulated ERK1/2 activation. MUC1 promoter activation by TNF-alpha also was blocked by mithramycin A, an inhibitor of Sp1, as well as either deletion or mutation of a putative Sp1 binding site in the MUC1 promoter located between nucleotides -99 and -90. TNF-alpha-stimulated binding of Sp1 to the MUC1 promoter in intact cells was demonstrated by chromatin immunoprecipitation assay. We conclude that TNF-alpha induces MUC1 gene transcription through a TNFR1 --> MEK1/2 --> ERK1 --> Sp1 pathway.

The Insulin Receptor Substrate (IRS) proteins are key players in insulin signal transduction and are the best studied targets of the insulin receptor. Ser/Thr phosphorylation of IRS proteins negatively modulates insulin signaling; therefore, the identification of IRS kinases and their target Ser phosphorylation sites is of physiological importance. Here we show that in Fao rat hepatoma cells, the IkappaB kinase beta (IKKbeta) is an IRS-1 kinase activated by selected inducers of insulin resistance, including sphingomyelinase, ceramide, and free fatty acids. Moreover, IKKbeta shares a repertoire of seven potential target sites on IRS-1 with protein kinase C zeta (PKCzeta), an IRS-1 kinase activated both by insulin and by inducers of insulin resistance. We further show that mutation of these seven sites (Ser-265, Ser-302, Ser-325, Ser-336, Ser-358, Ser-407, and Ser-408) confers protection from the action of IKKbeta and PKCzeta when they are overexpressed in Fao cells or primary hepatocytes. This enables the mutated IRS proteins to better propagate insulin signaling. These findings suggest that insulin-stimulated IRS kinases such as PKCzeta overlap with IRS kinases triggered by inducers of insulin resistance, such as IKKbeta, to phosphorylate IRS-1 on common Ser sites.

Liver fatty acid binding protein (L-FABP) contains amino acids that are known to possess antioxidant function. In this study, we tested the hypothesis that L-FABP may serve as an effective endogenous cytoprotectant against oxidative stress. Chang liver cells were selected as the experimental model because of their undetectable L-FABP mRNA level. Full-length L-FABP cDNA was subcloned into the mammalian expression vector pcDNA3.1 (pcDNA-FABP). Chang cells were stably transfected with pc-DNA-FABP or vector (pcDNA3.1) alone. Oxidative stress was induced by incubating cells with 400 micromol/L H2O2 or by subjecting cells to hypoxia/reoxygenation. Total cellular reactive oxygen species (ROS) was determined using the fluorescent probe DCF. Cellular damage induced by hypoxia/reoxygenation was assayed by lactate dehydrogenase (LDH) release. Expression of L-FABP was documented by regular reverse transcription polymerase chain reaction (RT-PCR), real-time RT-PCR, and Western blot. The pcDNA-FABP-transfected cells expressed full-length L-FABP mRNA, which was absent from vector-transfected control cells. Western blot showed expression of 14-kd L-FABP protein in pcDNA-FABP-transfected cells, but not in vector-transfected cells. Transfected cells showed decreased DCF fluorescence intensity under oxidative stress (H2O2 and hypoxia/reoxygenation) conditions versus control in inverse proportion to the level of L-FABP expression. Lower LDH release was observed in the higher L-FABP-expressed cells in hypoxia/reoxygenation experiments. In conclusion, we successfully transfected and cloned a Chang liver cell line that expressed the L-FABP gene. The L-FABP-expressing cell line had a reduced intracellular ROS level versus control. This finding implies that L-FABP has a significant role in oxidative stress.