Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51812 (mitogen-activated protein)
 10,636 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Curcumin (diferuloylmethane) is one of the phytophenolic compounds found in the turmeric plant with anti-inflammatory and anticarcinogenic activities. One possible mechanism for these activities is the inhibition of prostaglandin (PG) E(2) formation. In this study and other reports, curcumin suppresses interleukin-1beta-induced formation of prostaglandin E(2) in a concentration-dependent manner. Interleukin-1beta-induced microsomal prostaglandin E synthase 1 (mPGES-1) and cyclooxygenase-2 were attenuated by curcumin at the protein and mRNA levels, but a more dramatic inhibition of mPGES-1 expression was observed at lower concentrations of curcumin in A549 human lung epithelial cells. The inhibition of mPGES-1 expression by curcumin shifted the arachidonic acid profile from PGE(2) to PGF(2alpha) and 6-keto-PGF(1alpha) as major metabolites. The expression of early growth response gene 1 (EGR-1), a key transcription factor of cytokine-induced mPGES-1, was inhibited by curcumin. Incubation with siRNA for EGR-1 inhibited interleukin (IL)-1beta-induced mPGES-1, and the controlled expression of EGR-1 increased the mPGES-1 expression. Several proinflammatory signaling molecules, such as nuclear factor kappaB (NF-kappaB) and mitogen-activated protein kinases, are also known to affect curcumin-regulated gene expression. Curcumin inhibited IkappaBalpha phosphorylation and degradation and thus reduced the expression of mPGES-1. Curcumin suppressed cytokine-induced mPGES-1 by inhibiting phosphorylation of Jun N-terminal kinase (JNK)1/2. However, EGR-1 expression was suppressed by lower concentrations of curcumin, as compared with JNK1/2 and IkappaBalpha. These results indicate that curcumin inhibits IL-1beta-induced PGE(2) formation by inhibiting the expression of mPGES-1 that is mediated by suppression of EGR-1 expression as well as NF-kappaB and JNK1/2.
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PMID:Curcumin suppresses interleukin 1beta-mediated microsomal prostaglandin E synthase 1 by altering early growth response gene 1 and other signaling pathways. 1608 77

The root of Stellera chamaejasme L. is a traditional Chinese herb termed Rui Xiang Lang Du and has been used to treat solid tumors, tuberculosis and psoriasis. Exactly how S. chamaejasme L. regulates cellular responses remains unclear. We examined four biflavonoids isolated from S. chamaejasme L., including isochamaejasmin, two of its stereo-isomers and a methyl derivative, in functional assays originally designed to screen ligands for the G protein-coupled formyl peptide receptor-like 1 (FPRL1). Isochamaejasmin was found to induce the expression of a nuclear factor (NF)-kappaB-directed reporter gene in transfected HeLa cells with an EC50 of 3.23 microM, independently of FPRL1. The isochamaejasmin-stimulated NF-kappaB reporter activity was accompanied by nuclear translocation of NF-kappaB proteins and was blocked by a dominant-negative construct of IkappaBalpha. Isochamaejasmin also induced time-dependent phosphorylation of the mitogen-activated protein kinases extracellular signal-regulated kinase 1/2 and p38, and a novel protein kinase C (PKCdelta). Likewise, inhibition of these kinases with the respective pharmacological inhibitors significantly reduced the isochamaejasmin-stimulated NF-kappaB activation. It is noteworthy that the two stereoisomers and the methyl derivative did not induce detectable activation of NF-kappaB and were more cytotoxic than isochamaejasmin, which could partially rescue cycloheximide-induced apoptosis. Inhibition of NF-kappaB activation reversed the anti-apoptotic effect of isochamaejasmin. These results provide the first evidence for a potential mechanism of action by S. chamaejasme L., and indicate that structurally similar compounds derived from S. chamaejasme L. may have different pharmacological properties.
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PMID:Stereospecific induction of nuclear factor-kappaB activation by isochamaejasmin. 1614 13

Aberrant expression of cyclooxygenase-2 (COX-2) has been implicated in tumor promotion. Resveratrol, a phytoalexin present in grapes, was reported to inhibit multistage mouse skin carcinogenesis. In the present study, we found that topically applied resveratrol significantly inhibited COX-2 expression induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Resveratrol-suppressed phosphorylation and subsequent degradation of IkappaBalpha, thereby inhibiting activation of nuclear factor-kappaB (NF-kappaB) in TPA-stimulated mouse skin. Pretreatment with resveratrol also suppressed TPA-induced phosphorylation of extracellular signal-regulated protein kinase (ERK) and p38 mitogen-activated protein (MAP) kinase. Resveratrol blunted TPA-induced phosphorylation of p65 and its interaction with CBP/p300, rendering NF-kappaB transcriptionally inactive. To get further insights into the molecular basis of NF-kappaB inactivation by resveratrol, we examined the role of IkappaB kinase (IKK) in mediating TPA-induced activation of NF-kappaB and COX-2 expression. TPA treatment led to rapid induction of IKK activity in mouse skin, which was abolished either by resveratrol or an IKK inhibitor Bay 11-7082. Topical application of Bay 11-7082 also abrogated TPA-induced NF-kappaB activation and COX-2 expression, supporting the involvement of IKK in TPA-induced COX-2 expression. Taken together, the above findings suggest that resveratrol targets IKK in blocking TPA-induced NF-kappaB activation and COX-2 expression in mouse skin in vivo.
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PMID:Resveratrol inhibits phorbol ester-induced expression of COX-2 and activation of NF-kappaB in mouse skin by blocking IkappaB kinase activity. 1647 81

Lnk, with APS and SH2-B (Src homology 2-B), belongs to a family of SH2-containing proteins with potential adaptor functions. Lnk regulates growth factor and cytokine receptor-mediated pathways implicated in lymphoid, myeloid, and platelet homeostasis. We have previously shown that Lnk is expressed and up-regulated in vascular endothelial cells (ECs) in response to tumor necrosis factor-alpha (TNFalpha). In this study, we have shown that, in ECs, Lnk down-regulates the expression, at both mRNA and protein levels, of the proinflammatory molecules VCAM-1 and E-selectin induced by TNFalpha. Mechanistically, our data indicated that, in response to TNFalpha, NFkappaB/p65 phosphorylation and translocation as well as IkappaBalpha phosphorylation and degradation were unchanged, suggesting that Lnk does not modulate NFkappaB activity. However, Lnk activates phosphatidylinositol 3-kinase (PI3K) as reflected by Akt phosphorylation. Our results identify endothelial nitric-oxide synthase as a downstream target of Lnk-mediated activation of the PI3K/Akt pathway and HO-1 as a new substrate of Akt. We found that sustained Lnk-mediated activation of PI3K in TNFalpha-activated ECs correlated with the inhibition of ERK1/2 phosphorylation, whereas phosphorylation of p38 and c-Jun NH(2)-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs) was unchanged. ERK1/2 inhibition decreases VCAM-1 expression in TNFalpha-treated ECs. Collectively, our results identify the adaptor Lnk as a negative regulator in the TNFalpha-signaling pathway mediating ERK inhibition and suggest a role for Lnk in the interplay between PI3K and ERK triggered by TNFalpha in ECs.
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PMID:The adaptor molecule Lnk negatively regulates tumor necrosis factor-alpha-dependent VCAM-1 expression in endothelial cells through inhibition of the ERK1 and -2 pathways. 1664 35

Double-stranded RNA-dependent protein kinase (PKR), a ubiquitously expressed serine/threonine kinase, has been implicated in the regulation or modulation of cell growth through multiple signaling pathways, but how PKR regulates tumor necrosis factor (TNF)-induced signaling pathways is poorly understood. In the present study, we used fibroblasts derived from PKR gene-deleted mice to investigate the role of PKR in TNF-induced activation of nuclear factor-kappaB (NF-kappaB), mitogen-activated protein kinases (MAPKs) and growth modulation. We found that in wild-type mouse embryonic fibroblast (MEF), TNF induced NF-kappaB activation as measured by DNA binding but deletion of PKR abolished this activation. This inhibition was associated with suppression of inhibitory subunit of NF-kappaB (IkappaB)alpha kinase (IKK) activation, IkappaBalpha phosphorylation and degradation, p65 phosphorylation and nuclear translocation, and NF-kappaB-dependent reporter gene transcription. TNF-induced Akt activation needed for IKK activation was also abolished by deletion of PKR. NF-kappaB activation was diminished in PKR-deleted cells transfected with TNF receptor (TNFR) 1, TNFR-associated death domain and TRAF2 plasmids; NF-kappaB activated by NF-kappaB-inducing kinase, IKK or p65, however, was minimally affected. Among the MAPKs, it was interesting that whereas TNF-induced c-Jun N-terminal kinase (JNK) activation was abolished, activation of p44/p42 MAPK and p38 MAPK was potentiated in PKR-deleted cells. TNF induced the expression of NF-kappaB-regulated gene products cyclin D1, c-Myc, matrix metalloproteinase-9, survivin, X-linked inhibitor-of-apoptosis protein (IAP), IAP1, Bcl-x(L), A1/Bfl-1 and Fas-associated death domain protein-like IL-1beta-converting enzyme-inhibitory protein in wild-type MEF but not in PKR-/- cells. Similarly, TNF induced the proliferation of wild-type cells, but this proliferation was completely suppressed in PKR-deleted cells. Overall, our results indicate that PKR differentially regulates TNF signaling; IKK, Akt and JNK were positively regulated, whereas p44/p42 MAPK and p38 MAPK were negatively regulated.
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PMID:Genetic deletion of PKR abrogates TNF-induced activation of IkappaBalpha kinase, JNK, Akt and cell proliferation but potentiates p44/p42 MAPK and p38 MAPK activation. 1692 32

The inhibitor of apoptosis protein (IAP) family of molecules regulates apoptotic processes triggered by various stimuli. However, the mechanisms involved in the regulation of the IAP genes are not fully understood. In this report, we examined roles of nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein (MAP) kinases in tumor necrosis factor-alpha (TNF-alpha)-induced expression of IAP genes. In human endothelial cells, TNF-alpha induced c-IAP1 and c-IAP2, but not XIAP and TIAP/Survivin, at the transcriptional level. Inactivation of NF-kappaB by overexpression of a super-repressor mutant of IkappaBalpha did not affect the induction of IAPs by TNF-alpha. In contrast, extracellular signal-regulated kinase, p38 MAP kinase, and c-Jun N-terminal kinase were activated after stimulation with TNF-alpha, and inhibition of each kinase by PD098059, SB203580, curcumin, or SP600125 substantially attenuated the TNF-alpha-induced c-IAP1 and c-IAP2 expression. To examine whether the MAP kinases-mediated induction of IAPs contributes to survival of TNF-alpha-exposed cells, cells were pretreated with MAP kinase inhibitors and stimulated with TNF-alpha. Treatment with kinase inhibitors alone did not induce apoptosis but enhanced markedly TNF-alpha-triggered apoptosis. Furthermore, overexpression of either c-IAP1 or c-IAP2 diminished the apoptosis-promoting effects of MAP kinase inhibitors. These data indicated that TNF-alpha induced expression of c-IAP1 and c-IAP2 via MAP kinases, but not via NF-kappaB, and that MAP kinases participated in the inhibition of apoptosis by induction of c-IAPs in TNF-alpha-stimulated endothelial cells.
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PMID:MAP kinase-dependent, NF-kappaB-independent regulation of inhibitor of apoptosis protein genes by TNF-alpha. 1713 55

Humulone, a bitter acid derived from hop (Humulus lupulus L.), possesses antioxidative, anti-inflammatory and other biologically active activities. Although humulone has been reported to inhibit chemically induced mouse skin tumor promotion, the underlying mechanisms are yet to be elucidated. Since an inappropriate over-expression of cyclooxygenase-2 (COX-2) is implicated in carcinogenesis, we investigated effects of humulone on COX-2 expression in mouse skin stimulated with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Topical application of humulone (10 mumol) significantly inhibited TPA-induced epidermal COX-2 expression. Humulone also diminished TPA-induced DNA binding of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). Pre-treatment with humulone attenuated TPA-induced phosphorylation of p65 and nuclear translocation of NF-kappaB subunit proteins. Humulone blunted TPA-induced activation of inhibitory kappaB (IkappaB) kinase (IKK) in mouse skin, which accounts for its suppression of phosphorylation and subsequent degradation of IkappaBalpha. An in vitro kinase assay revealed that humulone could directly inhibit the catalytic activity of IKKbeta. Humulone suppressed the activation of mitogen-activated protein kinases (MAPKs) in TPA-treated mouse skin. The roles of extracellular signal-regulated protein kinase-1/2 and p38 MAPK in TPA-induced activation of NF-kappaB in mouse skin had been defined in our previous studies. The present study revealed that topical application of SP600125, a pharmacological inhibitor of c-Jun-N-terminal kinase (JNK), abrogated the activation of AP-1 and the expression of COX-2 in TPA-treated mouse skin. Taken together, humulone suppressed TPA-induced activation of NF-kappaB and AP-1 and subsequent expression of COX-2 by blocking upstream kinases IKK and JNK, respectively, which may account for its antitumor-promoting effects on mouse skin carcinogenesis.
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PMID:Humulone inhibits phorbol ester-induced COX-2 expression in mouse skin by blocking activation of NF-kappaB and AP-1: IkappaB kinase and c-Jun-N-terminal kinase as respective potential upstream targets. 1737 74

The cholecystokine (CCK) analogue cerulein causes pathophysiological, morphological, and biochemical events similar to various aspects of human pancreatitis. Doses of CCK or cerulein beyond those that cause the maximum pancreatic secretion of amylase and lipase result in pancreatitis, which is characterized by a dysregulation of the digestive enzyme production and cytoplasmic vacuolization and the death of acinar cells, edema formation, and an infiltration of inflammatory cells into the pancreas. This study aims to investigate whether cerulein induces IL-8 expression in pancreatic acinar cells, and whether cerulein-induced IL-8 expression is inhibited in the cells transfected with mutant genes for c-jun (TAM-67), or IkappaBalpha (MAD-3) or treated inhibitors of mitogen-activated protein kinases (MAPKs). As a result, cerulein induced IL-expression, which was inhibited in the cells transfected with TAM-67 or MAD-3 or treated inhibitors of MAPK. In conclusion, activation of MAPK, nuclear factor-kappaB (NF-kappaB), and activator protein-1 (AP-1) may be the upstream signaling for cerulein-induced IL-8 expression in pancreatic acinar cells.
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PMID:Role of mitogen-activated protein kinases, NF-kappaB, and AP-1 on cerulein-induced IL-8 expression in pancreatic acinar cells. 1738 81

To develop novel mechanism-based preventive approaches for lung cancer, we examined the effect of oral consumption of a human achievable dose of pomegranate fruit extract (PFE) on growth, progression, angiogenesis, and signaling pathways in two mouse lung tumor protocols. Benzo(a)pyrene [B(a)P] and N-nitroso-tris-chloroethylurea (NTCU) were used to induce lung tumors, and PFE was given in drinking water to A/J mice. Lung tumor yield was examined on the 84th day and 140 days after B(a)P dosing and 240 days after NTCU treatment. Mice treated with PFE and exposed to B(a)P and NTCU had statistically significant lower lung tumor multiplicities than mice treated with carcinogens only. Tumor reduction was 53.9% and 61.6% in the B(a)P + PFE group at 84 and 140 days, respectively, compared with the B(a)P group. The NTCU + PFE group had 65.9% tumor reduction compared with the NTCU group at 240 days. Immunoblot analysis and immunohistochemistry were used to determine effect on cell survival pathways and markers of cellular proliferation and angiogenesis. PFE treatment caused inhibition of (a) activation of nuclear factor-kappaB and IkappaBalpha kinase, (b) degradation and phosphorylation of IkappaBalpha, (c) phosphorylation of mitogen-activated protein kinases (extracellular signal-regulated kinase 1/2, c-Jun NH(2)-terminal kinase 1/2, and p38), (d) phosphatidylinositol 3-kinase (p85 and p110), (e) phosphorylation of Akt at Thr(308), (f) activation of mammalian target of rapamycin signaling, (g) phosphorylation of c-met, and (h) markers of cell proliferation (Ki-67 and proliferating cell nuclear antigen) and angiogenesis (inducible nitric oxide synthase, CD31, and vascular endothelial growth factor) in lungs of B(a)P- and NTCU-treated mice. Thus, our data show that PFE significantly inhibits lung tumorigenesis in A/J mice and merits investigation as a chemopreventive agent for human lung cancer.
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PMID:Oral consumption of pomegranate fruit extract inhibits growth and progression of primary lung tumors in mice. 1738 58

The modulation of intracellular signaling network involved in an inappropriate expression of cyclooxygenase-2 (COX-2) is a pragmatic approach for chemoprevention with a wide variety of dietary phytochemicals. Epigallocatechin gallate (EGCG), a major green tea polyphenol, is one of the most extensively investigated chemopreventive agents. Our previous study revealed that EGCG inhibited expression of COX-2 and activation of mitogen-activated protein kinases (MAPKs) in mouse skin stimulated with a prototype tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA). This study was aimed at identifying transcription factors as molecular targets of EGCG in downregulating COX-2 expression. We found that EGCG inhibited TPA-induced DNA binding of NF-kappaB and CREB in mouse skin in vivo. EGCG also suppressed TPA-induced phosphorylation and subsequent degradation of IkappaBalpha, and prevented nuclear translocation of p65. We also examined whether extracellular signal-regulated protein kinase (ERK) and p38 MAPK, which are known to regulate activation of NF-kappaB, can also modulate CREB DNA binding. Pretreatment with U0126 and SB203580, pharmacological inhibitors of ERK and p38 MAPK, respectively, showed that SB203580, but not U0126, attenuated TPA-induced CREB DNA binding in mouse skin. Taken together, EGCG inhibited TPA-induced DNA binding of NF-kappaB and CREB by blocking activation of p38 MAPK, which may provide a molecular basis of COX-2 inhibition by EGCG in mouse skin in vivo.
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PMID:Epigallocatechin gallate inhibits phorbol ester-induced activation of NF-kappa B and CREB in mouse skin: role of p38 MAPK. 1740 63


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