Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.10 (IKK)
 4,900 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tissue factor (TF) has been shown to be up-regulated in endothelial cells by the inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) as well as by the main angiogenic factor VEGF. Since both stimuli induce the transcription factor EGR-1, which is critically involved in TF gene regulation, we used EGR-1-dependent TF induction as a model to identify potential cross-talks between the various signal transduction cascades initiated by VEGF and TNF-alpha. The data show that at the MAP kinase level, VEGF mainly activates ERK1/2 and p38 MAP kinases in human endothelial cells. TNF-alpha is able to activate all three MAP kinase cascades as well as the classical inflammatory IkappaB/NFkappaB pathway. Furthermore, the MEK/ERK module of MAP kinases appears to act as the convergence point of VEGF- and TNF-alpha-initiated signaling cascades, which lead to the activation of EGR-1 and subsequent TF expression, whereas the upstream signals are distinct. We found that induction of TF by VEGF via EGR-1 is strongly PKC dependent. The TNF-alpha-initiated MEK/ERK cascade connected to EGR-1 and TF expression is clearly less sensitive to PKC inhibition. TNF-alpha-mediated activation of MEK/ERK and EGR-1 can be blocked by adenoviral expression of a dominant negative mutant of IKK2, whereas the VEGF signaling pathway is unaffected. Thus, our data demonstrate a new link between the classical inflammatory IKK/IkappaB and the MEK/ERK cascades triggered by TNF-alpha. The additional finding that EGF induces ERK and EGR-1 in a PKC-independent manner and that this signal is not sufficient to up-regulate TF emphasizes the importance of a VEGF-specific signaling pattern for the induction of TF.
 ...
PMID:Specificity, diversity, and convergence in VEGF and TNF-alpha signaling events leading to tissue factor up-regulation via EGR-1 in endothelial cells. 1114 11

Vascular endothelial cells are continuously exposed to mechanical (e.g., shear stress) and chemical (e.g., growth factors) stimuli. It is important to elucidate the mechanisms by which cells perceive and integrate these different stimuli to regulate the downstream signaling pathways. We (50) have previously reported the shear-induced interplay between two membrane receptors, integrins and Flk-1. In the present study, we investigated the molecular mechanisms regulating the downstream IkappaB kinase (IKK) pathway in response to shear stress and VEGF. Both shear stress and VEGF induced a transient increase of IKK activity. These effects were inhibited by SU-1498, a specific Flk-1 inhibitor, and by a negative mutant of Casitas B-lineage lymphoma (Cbl) with tyrosine-to-phenylalanine mutations at sites 700, 731, and 774 (Cbl(nm)). Because Flk-1 and Cbl form a complex upon shearing or VEGF applications (50), these results suggest that shear stress and VEGF activate IKK via the receptor Flk-1 and its recruitment of the adapter protein Cbl. The inhibition of the shear- and VEGF-induced IKK activities by a negative mutant of Akt indicates that Akt acts upstream to IKK in response to shear stress and VEGF. Furthermore, SU-1498 and Cbl(-nm) abolished the shear- and VEGF-induced Akt activity, indicating that Akt acts at a level downstream to Flk-1 and Cbl. Therefore, our results indicate that the signaling events induced by shear stress and VEGF converge at the membrane receptor Flk-1 and that these stimuli share the Flk-1/Cbl/Akt pathway in activating IKK activation.
 ...
PMID:Shear stress and VEGF activate IKK via the Flk-1/Cbl/Akt signaling pathway. 1455 Oct 58

The NF-kappaB family of transcription factors has been shown to be constitutively activated in various human malignancies, including leukemias, lymphomas, and a number of solid tumors. NF-kappaB is hypothesized to contribute to development and/or progression of malignancy by regulating the expression of genes involved in cell growth and proliferation, anti-apoptosis, angiogenesis, and metastasis. Prostate cancer cells have been reported to have constitutive NF-kappaB activity due to increased activity of the IkappaB kinase complex. Furthermore, an inverse correlation between androgen receptor (AR) status and NF-kappaB activity was observed in prostate cancer cell lines. NF-kappaB may promote cell growth and proliferation in prostate cancer cells by regulating expression of genes such as c-myc, cyclin D1, and IL-6. NF-kappaB may also inhibit apoptosis in prostate cancer cells through activation of expression of anti-apoptotic genes, such as Bcl-2, although pro-apoptotic activity of NF-kappaB has also been reported. NF-kappaB-mediated expression of genes involved in angiogenesis (IL-8, VEGF), and invasion and metastasis (MMP9, uPA, uPA receptor) may further contribute to the progression of prostate cancer. Constitutive NF-kappaB activity has also been demonstrated in primary prostate cancer tissue samples and suggested to have prognostic importance for a subset of primary tumors. The limited number of samples analyzed in those studies and the relative lack of NF-kappaB target genes identified in RNA expression microarray analyses of prostate cancer cells suggest that further studies will be required in order to determine if NF-kappaB actually plays a role in human prostate cancer development, and/or progression, and to characterize its potential as a therapeutic target.
 ...
PMID:NF-kappaB activation in human prostate cancer: important mediator or epiphenomenon? 1468 84

Nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1) transcription factors regulate many important biological and pathological processes. Activation of NF-kappaB is regulated by the inducible phosphorylation of NF-kappaB inhibitor IkappaB by IkappaB kinase. In contrast, Fos, a key component of AP-1, is primarily transcriptionally regulated by serum responsive factors (SRFs) and ternary complex factors (TCFs). Despite these different regulatory mechanisms, there is an intriguing possibility that NF-kappaB and AP-1 may modulate each other, thus expanding the scope of these two rapidly inducible transcription factors. To determine whether NF-kappaB activity is involved in the regulation of fos expression in response to various stimuli, we analyzed activity of AP-1 and expression of fos, fosB, fra-1, fra-2, jun, junB, and junD, as well as AP-1 downstream target gene VEGF, using MDAPanc-28 and MDAPanc-28/IkappaBalphaM pancreatic tumor cells and wild-type, IKK1-/-, and IKK2-/- murine embryonic fibroblast cells. Our results show that elk-1, a member of TCFs, is one of the NF-kappaB downstream target genes. Inhibition of NF-kappaB activity greatly decreased expression of elk-1. Consequently, the reduced level of activated Elk-1 protein by extracellular signal-regulated kinase impeded constitutive, serum-, and superoxide-inducible c-fos expression. Thus, our study revealed a distinct and essential role of NF-kappaB in participating in the regulation of elk-1, c-fos, and VEGF expression.
 ...
PMID:NF-kappaB and AP-1 connection: mechanism of NF-kappaB-dependent regulation of AP-1 activity. 1531 85

Guggulsterone, derived from Commiphora mukul and used to treat obesity, diabetes, hyperlipidemia, atherosclerosis, and osteoarthritis, has been recently shown to antagonize the farnesoid X receptor and decrease the expression of bile acid-activated genes. Because activation of NF-kappaB has been closely linked with inflammatory diseases affected by guggulsterone, we postulated that it must modulate NF-kappaB activation. In the present study, we tested this hypothesis by investigating the effect of this steroid on the activation of NF-kappaB induced by inflammatory agents and carcinogens. Guggulsterone suppressed DNA binding of NF-kappaB induced by tumor necrosis factor (TNF), phorbol ester, okadaic acid, cigarette smoke condensate, hydrogen peroxide, and interleukin-1. NF-kappaB activation was not cell type-specific, because both epithelial and leukemia cells were inhibited. Guggulsterone also suppressed constitutive NF-kappaB activation expressed in most tumor cells. Through inhibition of IkappaB kinase activation, this steroid blocked IkappaBalpha phosphorylation and degradation, thus suppressing p65 phosphorylation and nuclear translocation. NF-kappaB-dependent reporter gene transcription induced by TNF, TNFR1, TRADD, TRAF2, NIK, and IKK was also blocked by guggulsterone but without affecting p65-mediated gene transcription. In addition, guggulsterone decreased the expression of gene products involved in anti-apoptosis (IAP1, xIAP, Bfl-1/A1, Bcl-2, cFLIP, and survivin), proliferation (cyclin D1 and c-Myc), and metastasis (MMP-9, COX-2, and VEGF); this correlated with enhancement of apoptosis induced by TNF and chemotherapeutic agents. Overall, our results indicate that guggulsterone suppresses NF-kappaB and NF-kappaB-regulated gene products, which may explain its anti-inflammatory activities.
 ...
PMID:Guggulsterone inhibits NF-kappaB and IkappaBalpha kinase activation, suppresses expression of anti-apoptotic gene products, and enhances apoptosis. 1532 87

This study attempts to address an important clinical issue by identifying potential candidates of VEGF signaling through Flt-1 receptor that trigger angiogenic signal under ischemic stress. To determine the significance of VEGF-Flt-1 (VEGFR1) signaling in ischemic preconditioned (PC) myocardium, we used heterozygous Flt-1 knockout (KO) mice to dissect the pathway and identify candidate genes involved in VEGF signaling. DNA microarrays were employed to detect, characterize and distinguish altered myocardial gene expression by comparing between wild type (WT) CD-1 and heterozygous Flt-1 KO mice when exposed to ischemia (30 min) and reperfusion (2 h). Moreover, KO mice demonstrated reduced beneficial effects of PC when compared to the WT with PC. In the KO and WT mice, the % recovery of the left ventricular developed pressure and the maximum first derivative of the developed pressure after ischemia/reperfusion without PC were similar. However, when animals were subjected to PC, the left ventricular functional recovery throughout the reperfusion period was significantly lower in KO mice than in WT mice. These results indicate for the first time that in the heterozygous Flt-1 KO mice, PC is not as effective as that found in WT. This observation may be due to downregulation of several important genes such as growth-regulated oncogene 1 (Gro1), heat shock proteins (HSP), I kappa B kinase beta (IKK beta), colony-stimulating factor-1 (CSF-1) and annexin A7, suggesting the importance of VEGF-Flt-1 receptor signaling during PC.
 ...
PMID:Ischemic preconditioning-mediated cardioprotection is disrupted in heterozygous Flt-1 (VEGFR-1) knockout mice. 1569 41

Recent studies indicate that natural isothiocyanates, such as sulforaphane (SFN) and phenethyl isothiocyanate (PEITC) possess strong antitumor activities in vitro and in vivo. The nuclear factor kappa B (NF-kappaB) is believed to play an important role in cancer chemoprevention due to its involvement in tumor cell growth, proliferation, angiogenesis, invasion, apoptosis, and survival. In this study, we investigated the effects and the molecular mechanisms of SFN and PEITC on NF-kappaB transcriptional activation and NF-kappaB-regulated gene expression in human prostate cancer PC-3 C4 cells. Treatment with SFN (20 and 30 microM) and PEITC (5 and 7.5 microM) significantly inhibited NF-kappaB transcriptional activity, nuclear transloction of p65, and gene expression of NF-kappaB-regulated VEGF, cylcin D1, and Bcl-X(L) in PC-3 C4 cells. To further elucidate the mechanism, we utilized the dominant-negative mutant of inhibitor of NF-kappaB alpha (IkappaBalpha) (SR-IkappaBalpha). Analogous to treatments with SFN and PEITC, SR-IkappaBalpha also strongly inhibited NF-kappaB transcriptional activity as well as VEGF, cylcin D1, and Bcl-X(L) expression. Furthermore, SFN and PEITC also inhibited the basal and UVC-induced phosphorylation of IkappaBalpha and blocked UVC-induced IkappaBalpha degradation in PC-3 C4 cells. In examining the upstream signaling, we found that the dominant-negative mutant of IKKbeta (dnIKKbeta) possessed inhibitory effects similar to SFN and PEITC on NF-kappaB, VEGF, cylcin D1, Bcl-X(L) as well as IkappaBalpha phosphorylation. In addition, treatment with SFN and PEITC potently inhibited phosphorylation of both IKKbeta and IKKalpha and significantly inhibited the in vitro phosphorylation of IkappaBalpha mediated by IKKbeta. Taken together, these results suggest that the inhibition of SFN and PEITC on NF-kappaB transcriptional activation as well as NF-kappaB-regulated VEGF, cyclin D1, and Bcl-X(L) gene expression is mainly mediated through the inhibition of IKK phosphorylation, particularly IKKbeta, and the inhibition of IkappaBalpha phosphorylation and degradation, as well as the decrease of nuclear translocation of p65 in PC-3 cells.
 ...
PMID:Suppression of NF-kappaB and NF-kappaB-regulated gene expression by sulforaphane and PEITC through IkappaBalpha, IKK pathway in human prostate cancer PC-3 cells. 1585 23

A genome-wide phenotype screen was used to identify factors and pathways that induce proliferation of human umbilical vein endothelial cells (HUVEC). HUVEC proliferation is a recognized marker for factors that modulate vascularization. Screening "hits" included known proangiogenic factors, such as VEGF, FGF1, and FGF2 and additional factors for which a direct association with angiogenesis was not previously described. These include the kinase TBK1 as well as Toll-like receptor adaptor molecule and IFN regulatory factor 3. All three proteins belong to one signaling pathway that mediates induction of gene expression, including a mixture of secreted factors, which, in concert, mediate proliferative activity toward endothelial cells. TBK1 as the "trigger" of this pathway is induced under hypoxic conditions and expressed at significant levels in many solid tumors. This pattern of expression and the decreased expression of angiogenic factors in cultured cells upon RNA-interference-mediated ablation suggests that TBK1 is important for vascularization and subsequent tumor growth and a target for cancer therapy.
 ...
PMID:Identification of proangiogenic genes and pathways by high-throughput functional genomics: TBK1 and the IRF3 pathway. 1653 15

Celastrol, a quinone methide triterpene derived from the medicinal plant Tripterygium wilfordii, has been used to treat chronic inflammatory and autoimmune diseases, but its mechanism is not well understood. Therefore, we investigated the effects of celastrol on cellular responses activated by TNF, a potent proinflammatory cytokine. Celastrol potentiated the apoptosis induced by TNF and chemotherapeutic agents and inhibited invasion, both regulated by NF-kappaB activation. We found that TNF induced the expression of gene products involved in antiapoptosis (IAP1, IAP2, Bcl-2, Bcl-XL, c-FLIP, and survivin), proliferation (cyclin D1 and COX-2), invasion (MMP-9), and angiogenesis (VEGF) and that celastrol treatment suppressed their expression. Because these gene products are regulated by NF-kappaB, we postulated that celastrol mediates its effects by modulating the NF-kappaB pathway. We found that celastrol suppressed both inducible and constitutive NF-kappaB activation. Celastrol was found to inhibit the TNF-induced activation of IkappaBalpha kinase, IkappaBalpha phosphorylation, IkappaBalpha degradation, p65 nuclear translocation and phosphorylation, and NF-kappaB-mediated reporter gene expression. Recent studies indicate that TNF-induced IKK activation requires activation of TAK1, and we indeed found that celastrol inhibited the TAK1-induced NF-kappaB activation. Overall, our results suggest that celastrol potentiates TNF-induced apoptosis and inhibits invasion through suppression of the NF-kappaB pathway.
 ...
PMID:Celastrol, a novel triterpene, potentiates TNF-induced apoptosis and suppresses invasion of tumor cells by inhibiting NF-kappaB-regulated gene products and TAK1-mediated NF-kappaB activation. 1711 Apr 49

Gambogic acid (GA), a xanthone derived from the resin of the Garcinia hanburyi, has been recently demonstrated to bind transferrin receptor and exhibit potential anticancer effects through a signaling mechanism that is not fully understood. Because of the critical role of NF-kappaB signaling pathway, we investigated the effects of GA on NF-kappaB-mediated cellular responses and NF-kappaB-regulated gene products in human leukemia cancer cells. Treatment of cells with GA enhanced apoptosis induced by tumor necrosis factor (TNF) and chemotherapeutic agents, inhibited the expression of gene products involved in antiapoptosis (IAP1 and IAP2, Bcl-2, Bcl-x(L), and TRAF1), proliferation (cyclin D1 and c-Myc), invasion (COX-2 and MMP-9), and angiogenesis (VEGF), all of which are known to be regulated by NF-kappaB. GA suppressed NF-kappaB activation induced by various inflammatory agents and carcinogens and this, accompanied by the inhibition of TAK1/TAB1-mediated IKK activation, inhibited IkappaBalpha phosphorylation and degradation, suppressed p65 phosphorylation and nuclear translocation, and finally abrogated NF-kappaB-dependent reporter gene expression. The NF-kappaB activation induced by TNFR1, TRADD, TRAF2, NIK, TAK1/TAB1, and IKKbeta was also inhibited. The effect of GA mediated through transferrin receptor as down-regulation of the receptor by RNA interference reversed its effects on NF-kappaB and apoptosis. Overall our results demonstrate that GA inhibits NF-kappaB signaling pathway and potentiates apoptosis through its interaction with the transferrin receptor.
 ...
PMID:Gambogic acid, a novel ligand for transferrin receptor, potentiates TNF-induced apoptosis through modulation of the nuclear factor-kappaB signaling pathway. 2364 Sep 97


1 2 3 4 Next >>