The role of P38 MAPK and PKC in BLP induced TNF-alpha release, apoptosis, and NFkappaB activation in THP-1 monocyte cells

Role of MAPK/MNK1 signaling in virus replication

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Viruses are known to exploit cellular signaling pathways.

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MAPK is a major cell signaling pathway activated by diverse group of viruses.

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MNK1 regulates both cap-dependent and IRES-mediated mRNA translation.

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This review discuss the role of MAPK, particularly the role of MNK1 in virus replication.

Viruses are obligate intracellular parasites; they heavily depend on the host cell machinery to effectively replicate and produce new progeny virus particles. Following viral infection, diverse cell signaling pathways are initiated by the cells, with the major goal of establishing an antiviral state. However, viruses have been shown to exploit cellular signaling pathways for their own effective replication. Genome-wide siRNA screens have also identified numerous host factors that either support (proviral) or inhibit (antiviral) virus replication. Some of the host factors might be dispensable for the host but may be critical for virus replication; therefore such cellular factors may serve as targets for development of antiviral therapeutics. Mitogen activated protein kinase (MAPK) is a major cell signaling pathway that is known to be activated by diverse group of viruses. MAPK interacting kinase 1 (MNK1) has been shown to regulate both cap-dependent and internal ribosomal entry sites (IRES)-mediated mRNA translation. In this review we have discuss the role of MAPK in virus replication, particularly the role of MNK1 in replication and translation of viral genome.

Expression of Indoleamine 2,3-Dioxygenase Induced by IFN-γ and TNF-α as Potential Biomarker of Prostate Cancer Progression

Inflammation has been suggested to play an important role in onset and progression of prostate cancer (PCa). Histological analysis of prostatectomy specimens has revealed focal inflammation in early stage lesions of this malignancy. We addressed the role of inflammatory stimuli in the release of PCa-specific, tumor-derived soluble factors (PCa-TDSFs) already reported to be mediators of PCa morbidity, such as indoleamine 2,3-dioxygenase (IDO) and interleukin (IL)-6. Inflammation-driven production and functions of PCa-TDFSs were tested "in vitro" by stimulating established cell lines (CA-HPV-10 and PC3) with IFN-γ or TNF-α. Expression of genes encoding IDO, IL-6, IFN-γ, TNF-α, and their receptors was investigated in tumor tissues of PCa patients undergoing radical prostatectomy, in comparison with benign prostatic hyperplasia (BPH) specimens. IFN-γ and TNF-α-treatment resulted in the induction of IDO and IL-6 gene expression and release in established cell lines, suggesting that the elicitation of PCa-TDSFs by these cytokines might contribute to progression of cancer into an untreatable phenotype. An analysis based on timing of biochemical recurrence revealed the prognostic value of IDO but not IL-6 gene expression in predicting recurrence-free survival in patients (RFS) with PCa. In addition, a urine-based mRNA biomarker study revealed the diagnostic potential of IDO gene expression in urines of men at risk of PCa development.

Involvement of PI3K/Akt and p38 MAPK in the induction of COX-2 expression by bacterial lipopolysaccharide in murine adrenocortical cells

Previous studies from our laboratory demonstrated the involvement of COX-2 in the stimulation of steroid production by LPS in murine adrenocortical Y1 cells, as well as in the adrenal cortex of male Wistar rats. In this paper we analyzed signaling pathways involved in the induction of this key regulatory enzyme in adrenocortical cells and demonstrated that LPS triggers an increase in COX-2 mRNA levels by mechanisms involving the stimulation of reactive oxygen species (ROS) generation and the activation of p38 MAPK and Akt, in addition to the previously demonstrated increase in NFκB activity. In this sense we showed that: (1) inhibition of p38 MAPK or PI3K/Akt (pharmacological or molecular) prevented the increase in COX-2 protein levels by LPS, (2) LPS induced p38 MAPK and Akt phosphorylation, (3) antioxidant treatment blocked the effect of LPS on p38 MAPK phosphorylation and in COX-2 protein levels, (4) PI3K inhibition with LY294002 prevented p38 MAPK phosphorylation and, (5) the activity of an NFκB reporter was decreased by p38 MAPK or PI3K inhibition. These results suggest that activation of both p38 MAPK and PI3K/Akt pathways promote the stimulation of NFκB activity and that PI3K/Akt activity might regulate both p38 MAPK and NFκB signaling pathways. In summary, in this study we showed that in adrenal cells, LPS induces COX-2 expression by activating p38 MAPK and PI3K/Akt signaling pathways and that both pathways converge in the modulation of NFκB transcriptional activity.

Regulation of IL-8 promoter activity by verrucarin A in human monocytic THP-1 cells

Macrocyclic trichothecenes have been frequently detected in fungi in water-damaged buildings and exhibited higher toxicity than the well-studied trichothecenes; however, the mechanism underlying their toxicity has been poorly understood. In this study, transcriptional regulation of the cytokine interleukin (IL)-8 by a macrocyclic trichothecene, verrucarin A (VA), in human monocytic THP-1 cells is reported. Consistent with previous findings, VA was 100-fold more cytotoxic than deoxynivalenol (DON), while ochratoxin A (OA) was not cytotoxic. In cells transduced with the wild-type IL-8 promoter luciferase construct, VA induced a biphasic dose response composed of an upregulation of luciferase expression at low concentrations of 0.01-1 ng/ml and a downregulation at high levels of 10 ng/ml and higher. In contrast, DON induced a sigmoid-shaped dose response with the EC50 of 11.6 ng/ml, while OA did not markedly affect the IL-8 expression. When cells were transduced with IL-8 promoter with a mutation of transcription factor nuclear factor-κB (NF-κB)-binding site, VA (1 ng/ml), DON (1000 ng/ml), and tumor necrosis factor (TNF) α (20 ng/ml)-induced luciferase expression were impaired. In addition, the NF-κB inhibitor caffeic acid phenethyl ester inhibited VA-, DON-, and TNFα-induced luciferase expression. Mutation of the CCAAT/enhancer-binding protein (CEBP) β binding site of the IL-8 promoter affected only DON-, but not VA- and TNFα-induced luciferase expression. Taken together, these results suggested that VA activated IL-8 promoter via an NF-κB-dependent, but not CEBPβ-dependent, pathway in human monocytes.

Differential gene expressions of the MAPK signaling pathway in enterovirus 71-infected rhabdomyosarcoma cells

Background

Mitogen-activated protein kinase (MAPK) signaling pathway plays an important role in response to viral infection. The aim of this study was to explore the function and mechanism of MAPK signaling pathway in enterovirus 71 (EV71) infection of human rhabdomyosarcoma (RD) cells.

Methods

Apoptosis of RD cells was observed using annexin V-FITC/PI binding assay under a fluorescence microscope. Cellular RNA was extracted and transcribed to cDNA. The expressions of 56 genes of MAPK signaling pathway in EV71-infected RD cells at 8 h and 20 h after infection were analyzed by PCR array. The levels of IL-2, IL-4, IL-10, and TNF-α in the supernatant of RD cells infected with EV71 at different time points were measured by ELISA.

Results

The viability of RD cells decreased obviously within 48 h after EV71 infection. Compared with the control group, EV71 infection resulted in the significantly enhanced releases of IL-2, IL-4, IL-10 and TNF-α from infected RD cells (p < 0.05). At 8 h after infection, the expressions of c-Jun, c-Fos, IFN-β, MEKK1, MLK3 and NIK genes in EV71-infected RD cells were up-regulated by 2.08–6.12-fold, whereas other 19 genes (e.g. AKT1, AKT2, E2F1, IKK and NF-κB1) exhibited down-regulation. However, at 20 h after infection, those MAPK signaling molecules including MEKK1, ASK1, MLK2, MLK3, NIK, MEK1, MEK2, MEK4, MEK7, ERK1, JNK1 and JNK2 were up-regulated. In addition, the expressions of AKT2, ELK1, c-Jun, c-Fos, NF-κB p65, PI3K and STAT1 were also increased.

Conclusion

EV71 infection induces the differential gene expressions of MAPK signaling pathway such as ERK, JNK and PI3K/AKT in RD cells, which may be associated with the secretions of inflammatory cytokines and host cell apoptosis.

Inflammatory cytokine gene expression in THP-1 cells exposed to Stachybotrys chartarum and Aspergillus versicolor

Very little is known about the mechanisms that occur in human cells upon exposure to fungi as well as their mycotoxins. A better understanding of toxin-regulated gene expression would be helpful to identify safe levels of exposure and could eventually be the basis for establishing guidelines for remediation scenarios following a water intrusion event. In this research, cytokine mRNA expression patterns were investigated in the human monocytic THP-1 cell line exposed to fungal extracts of various fragment sizes obtained from Stachybotrys chartarum RTI 5802 and/or Aspergillus versicolor RTI 3843, two common and well-studied mycotoxin producing fungi. Cytokine mRNA expression was generally upregulated 2-10 times following a 24 h exposure to fungal extracts. Expression of the proinflammatory interleukin-1β, interleukin-8, and tumor necrosis factor-α genes increased while the anti-inflammatory gene interleukin-10 also increased albeit at very low level, suggesting that negative feedback regulation mechanism of production of proinflammatory cytokines initiated upon 24 h of incubation. In addition, submicron size extracts of A. versicolor caused significant death of THP-1 cells, whereas extracts of S. chartarum caused no cell death while the mixture of the two fungi had an intermediate effect. There was no general correlation between gene expression and fragment sizes, which suggests that all submicron fragments may contribute to inflammatory response.

A novel pathway responsible for lipopolysaccharide-induced translational regulation of TNF-α and IL-6 expression involves protein kinase C and fascin

Fascin, as a substrate of protein kinase C (PKC), is a well-known cytoskeletal regulatory protein required for cell migration, invasion, and adhesion in normal and cancer cells. In an effort to identify the role of fascin in PKC-mediated cellular signaling, its expression was suppressed by stable transfection of specific short hairpin RNAs (shRNAs) in mouse monocytic leukemia RAW264.7 cells. Suppression of fascin expression resulted in impaired cellular migration and invasion through extracellular matrix proteins. Unexpectedly, the specific shRNA transfectants exhibited a marked reduction in LPS-induced expression of TNF-α and IL-6 by blocking the translation of their mRNAs. Transient transfection assay using a luciferase expression construct containing the 3' untranslated region of TNF-α or IL-6 mRNA revealed a significant reduction in both LPS- and PMA- (the direct activator of PKC) induced reporter activity in cells transfected with fascin-specific shRNA, indicating that fascin-mediated translational regulation targeted 3' untranslated region. Furthermore, LPS-induced translational activation of reporter expression was blocked by a pharmacological inhibitor of PKC, and the dominant-negative form of PKCα attenuated LPS-induced translational activation. The same type of regulation was also observed in the human monocytic leukemia cell line THP-1 and in mouse peritoneal macrophages. These data demonstrate the involvement of fascin in the PKC-mediated translational regulation of TNF-α and IL-6 expression during the LPS response.

ST6Gal-I regulates macrophage apoptosis via α2-6 sialylation of the TNFR1 death receptor

Macrophages play a central role in innate immunity, however mechanisms regulating macrophage survival are not fully understood. Herein we describe a novel apoptotic pathway involving α2-6 sialylation of the TNFR1 death receptor by the ST6Gal-I sialyltransferase. Variant glycosylation of TNFR1 has not previously been implicated in TNFR1 function, and little is known regarding the TNFR1 glycan composition. To study sialylation in macrophages, we treated U937 monocytic cells with PMA, which stimulates both macrophage differentiation and apoptosis. Interestingly, macrophage differentiation induces ST6Gal-I down-regulation, leading to reduced α2-6 sialylation of selected receptors. To prevent loss of α2-6 sialylation, we forced constitutive expression of ST6Gal-I, and found that this strongly inhibited PMA-induced apoptosis. Given that PMA-mediated apoptosis is thought to result from up-regulation of TNFα, which then activates TNFR1, we next evaluated the α2-6 sialylation of TNFR1. U937 cells with forced ST6Gal-I displayed TNFR1 with elevated α2-6 sialylation, and this was associated with diminished TNFα-stimulated apoptosis. Correspondingly, removal of α2-6 sialylation from TNFR1 through either neuraminidase treatment or expression of ST6Gal-I shRNA markedly enhanced TNFα-mediated apoptosis. To confirm the physiologic importance of TNFR1 sialylation, we generated overexpressing ST6Gal-I transgenic mice. Peritoneal macrophages from transgenic lines displayed TNFR1 with elevated α2-6 sialylation, and these cells were significantly protected against TNFα-stimulated apoptosis. Moreover, greater numbers of thioglycollate-induced peritoneal cells were observed in transgenic mice. These collective results highlight a new mechanism of TNFR1 regulation, and further intimate that loss of α2-6 sialylation during macrophage differentiation may limit macrophage lifespan by sensitizing cells to TNFα-stimulated apoptosis.

Biosynthesis of promatrix metalloproteinase-9/chondroitin sulphate proteoglycan heteromer involves a Rottlerin-sensitive pathway

Background

Previously we have shown that a fraction of the matrix metalloproteinase-9 (MMP-9) synthesized by the macrophage cell line THP-1 was bound to a chondroitin sulphate proteoglycan (CSPG) core protein as a reduction sensitive heteromer. Several biochemical properties of the enzyme were changed when it was bound to the CSPG.

Methodology/Principal Findings

By use of affinity chromatography, zymography, and radioactive labelling, various macrophage stimulators were tested for their effect on the synthesis of the proMMP-9/CSPG heteromer and its components by THP-1 cells. Of the stimulators, only PMA largely increased the biosynthesis of the heteromer. As PMA is an activator of PKC, we determined which PKC isoenzymes were expressed by performing RT-PCR and Western Blotting. Subsequently specific inhibitors were used to investigate their involvement in the biosynthesis of the heteromer. Of the inhibitors, only Rottlerin repressed the biosynthesis of proMMP-9/CSPG and its two components. Much lower concentrations of Rottlerin were needed to reduce the amount of CSPG than what was needed to repress the synthesis of the heteromer and MMP-9. Furthermore, Rottlerin caused a minor reduction in the activation of the PKC isoenzymes δ, ε, θ and υ (PKD3) in both control and PMA exposed cells.

Conclusions/Significance

The biosynthesis of the proMMP-9/CSPG heteromer and proMMP-9 in THP-1 cells involves a Rottlerin-sensitive pathway that is different from the Rottlerin sensitive pathway involved in the CSPG biosynthesis. MMP-9 and CSPGs are known to be involved in various physiological and pathological processes. Formation of complexes may influence both the specificity and localization of the enzyme. Therefore, knowledge about biosynthetic pathways and factors involved in the formation of the MMP-9/CSPG heteromer may contribute to insight in the heteromers biological function as well as pointing to future targets for therapeutic agents.

BAFF and APRIL induce inflammatory activation of THP-1 cells through interaction with their conventional receptors and activation of MAPK and NF-κB

BACKGROUND

BAFF and APRIL, as closely related members of the TNF superfamily, are important regulators of B-cell survival. They share two receptors, TACI and BCMA, and BAFF can stimulate an additional receptor, BAFF-R. Although these molecules have been under intense investigation in order to identify their role in immune reactions, the effect of BAFF and APRIL on macrophage function has not been tested.

METHODS

The human macrophage-like cell line THP-1, which expresses BAFF/APRIL and all three of their receptors, was stimulated with recombinant human BAFF or APRIL or monoclonal antibodies against the receptors and the resulting cellular responses were investigated. Treatment of the cells with these agents induced the expression of pro-inflammatory mediators such as matrix metalloproteinase (MMP)-9 and IL-8. Suppression of the expression of these receptors using specific siRNAs resulted in the blocking of the response, confirming that these responses require specific interaction between BAFF/APRIL and their receptors. Inhibitors of MAPK and NF-κB blocked the expression of IL-8. Furthermore, inhibitors of MAPK blocked the BAFF-induced specific DNA binding activity of NF-κB.

CONCLUSION

These data indicate that BAFF and APRIL can induce inflammatory activation of THP-1 cells through the activation of MAPK, which leads to the subsequent activation of NF-κB.

Casein α s1 is expressed by human monocytes and upregulates the production of GM-CSF via p38 MAPK

Caseins are major constituents of mammalian milks that are thought to be exclusively expressed in mammary glands and to function primarily as a protein source, as well as to ameliorate intestinal calcium uptake. In addition, proinflammatory and immunomodulatory properties have been reported for bovine caseins. Our aim was to investigate whether human casein α s1 (CSN1S1) is expressed outside the mammary gland and possesses immunomodulatory functions in humans as well. For this purpose, CSN1S1 mRNA was detected in primary human monocytes and CD4(+) and CD8(+) T cells, but not in CD19(+) B cells. CSN1S1 protein was traceable in supernatants of cultured primary human CD14(+) monocytes by ELISA. Similarly, CSN1S1 mRNA and protein were detected in the human monocytic cell lines HL60, U937, and THP1 but not in Mono Mac 6 cells. Moreover, permeabilized human monocytes and HL60 cells could be stained by immunofluorescence, indicating intracellular expression. Recombinant human CSN1S1 was bound to the surface of Mono Mac 6 cells and upregulated the expression of GM-CSF mRNA in primary human monocytes and Mono Mac 6 cells in a time- and concentration-dependent manner. A similar increase in GM-CSF protein was found in the culture supernatants. CSN1S1-dependent upregulation of GM-CSF was specifically blocked by the addition of the p38 MAPK inhibitor ML3403. Our results indicated that human CSN1S1 may possess an immunomodulatory role beyond its nutritional function in milk. It is expressed in human monocytes and stimulates the expression of the proinflammatory cytokine GM-CSF.

Effects of dahuangzhechong pills on cytokines and mitogen activated protein kinase activation in rats with hepatic fibrosis

RELEVANCE TO ETHNOPHARMACOLOGY: Dahuangzhechong pill (DHZCP), a well-known and canonical Chinese medicine formula from "The Synopsis of Prescriptions of the Golden Chamber", is officially approved and recommended by Chinese association of integrative medicine for the prevention and treatment of hepatic fibrosis in China.

AIM OF THE STUDY

To test the hypothesis that therapeutic effects of DHZCP on hepatic fibrosis are conferred by regulating cytokine profile through a mitogen activated protein kinase (MAPK) pathway.

MATERIALS AND METHODS

Hepatic fibrosis is inducted by carbon tetrachloride (CCl(4)) in rats which then were randomly divided into six groups: hepatic fibrosis model group, high dose DHZCP group, low dose DHZCP group, Fufang Biejia Ruangan Pian (FBRP) group, Colchicine group and control group. Pathological, immunohistochemical, multiplex immunoassay and protein expression studies (Western blotting) are performed.

RESULTS

DHZCP significantly decreases the levels of alanine aminotransferase, aspartate aminotransferase, hyaluronic acid, laminin, type IV collagen and procollagen III, and reverses hepatic fibrosis in rat model. DHZCP also could reduce the expression of α-smooth muscle actin, and lower the serum level of tumor necrosis factor alpha (TNF-α) and interleukin 13 (IL-13). The expressions of phosphorylated p38 MAPK and extracellular signal-regulated kinase (ERK) are down-regulated, while no significant changes are found in phosphorylation of c-Jun N-terminal kinase (JNK).

CONCLUSIONS

DHZCP can alleviate hepatic fibrosis induced by CCl(4). The anti-fibrotic effects of DHZCP are conferred by decreasing the secretion of TNF-α and IL-13 through down-regulating p38 and ERK phosphorylation.

p38 MAP kinase inhibition promotes primary tumour growth via VEGF independent mechanism

Background

The surgical insult induces an inflammatory response that activates P38 MAP kinases and solid tumours can also release cytokines. Therfore inhibition of these pathways may reduce tumour growth We set out to examine the effects of P38-MAPK inhibition on apoptosis, proliferation, VEGF release and cell cycle effects in-vitro and on primary tumour growth in-vivo.

Methods

4T-1 cells (2 × 10⁵cells/well) were incubated, in 24 well plates with control, 25, 50 or 100 ng/ml of SB-202190 for 24 hours. Cells were subsequently asessed for apoptosis, proliferation, VEGF release and cell cycle analysis. Balb-c mice each received 1 × 10⁶ 4T1 cells subcutaneously in the flank and were then randomised to receive control or SB202190 (2.5 μM/kg) by intraperitoneal injection daily. Tumour size was measured alternate days and at day 24 animals were sacrificed and serum VEGF assessed.

Results

P38-MAPK inhibition in-vitro resulted in a significant reduction in proliferation (75.2 ± 8.4% vs. 100 ± 4.3%, p < 0.05) and G₁ cell cycle phase(35.9 ± 1.1% vs. 32.5 ± 0.6%, p < 0.05) but no significant changes in apoptosis or VEGF levels. In-vivo, P38-MAPK inhibition resulted in an increase in primary tumour growth (155.6 ± 34.9 vs. 86.7 ± 18.2 mm³, p < 0.05). P38-MAPK inhibition also lowered circulating VEGF levels but this difference was not significant (101.9 ± 27.1 ηg/ml compared to 158.6 ± 27.1 ηg/ml)

Conclusion

These findings demonstrate that P38-MAPK inhibition in-vitro reduces proliferation and G₁ cell cycle phase as well as promoting primary tumour growth in-vivo. These effects would appear to be independent of VEGF.

Lipopolysaccharide induces alteration of serotonin transporter in human intestinal epithelial cells

Intestinal serotoninergic activity and serotonin transporter (SERT) function have been shown to be altered in intestinal inflammatory diseases. Serotonin (5-HT) plays a critical role in the regulation of gastrointestinal physiology. Activity of 5-HT depends on its extracellular availability, partly modulated by SERT that transports 5-HT into the cell. Lipopolysaccharide (LPS) is a component of Gram-negative bacteria outer membrane, which acts as a potent activator of the inflammatory system in the intestine. The aim of this work was to determine, in the enterocyte-like cell line Caco-2, whether LPS treatment affects serotoninergic activity by acting on SERT. The results demonstrate that LPS treatment diminishes SERT activity in a dose- and period-dependent way. The kinetic study shows that V(max) was significantly reduced after treatment with LPS. The LPS effect on 5-HT uptake was, in part, mediated by protein kinase C (PKC) activation. The molecular expression of SERT revealed that LPS treatment did not affect the mRNA level or the SERT protein content in cell homogenate. The level of SERT protein, however, was reduced on brush border membrane. The LPS effect might be due to an alteration of the intracellular traffic of SERT which may, in part, be mediated by PKC activity.

Effects of NF-kappaB inhibitor on titanium particulate-induced inflammation in a murine model

BACKGROUND

Activation of nuclear factor kappa B (NF-kappaB) signaling in response to implant particulates may be critical in the pathogenesis of implant loosening after joint arthroplasty. The purpose of this study was to investigate the inhibitory effects of pyrrolidine dithiocarbamate (PDTC) in a murine model of inflammation induced by titanium (Ti) particulates.

MATERIALS AND METHODS

Ti particulates were introduced into established air pouches on C57BL/6J mice. Mice were injected intraperitoneally with either high-dose PDTC (100 mg/kg) or low-dose PDTC (50 mg/kg). Mice without drug treatment, as well as mice injected with saline alone were included. Each group consisted of sixteen mice. The membranes and lavage fluid were harvested 2 d or 7 d after injection of particulate suspension for histological and molecular analysis.

RESULTS

Histologic analysis showed that PDTC reduced inflammatory responses in air pouches, that is, thinner membrane and decreased cellular infiltration. In addition, PDTC reduced the release of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in the lavage fluid or supernatant of homogenates as evaluated by ELISA.

CONCLUSION

These results suggest that PDTC inhibits Ti particulate-induced inflammatory responses in the murine model; thus it represents a promising therapeutic candidate for the prevention and treatment of implant loosening.

6-Gingerol inhibits ROS and iNOS through the suppression of PKC-alpha and NF-kappaB pathways in lipopolysaccharide-stimulated mouse macrophages

Inflammation is involved in numerous diseases, including chronic inflammatory diseases and the development of cancer. Many plants possess a variety of biological activities, including antifungal, antibacterial and anti-inflammatory activities. However, our understanding of the anti-inflammatory effects of 6-gingerol is very limited. We used lipopolysaccharide (LPS)-stimulated macrophages as a model of inflammation to investigate the anti-inflammatory effects of 6-gingerol, which contains phenolic structure. We found that 6-gingerol exhibited an anti-inflammatory effect. 6-Gingerol could decrease inducible nitric oxide synthase and TNF-alpha expression through suppression of I-kappaB alpha phosphorylation, NF-kappaB nuclear activation and PKC-alpha translocation, which in turn inhibits Ca(2+) mobilization and disruption of mitochondrial membrane potential in LPS-stimulated macrophages. Here, we demonstrate that 6-gingerol acts as an anti-inflammatory agent by blocking NF-kappaB and PKC signaling, and may be developed as a useful agent for the chemoprevention of cancer or inflammatory diseases.