Protein kinase C-alpha coordinately regulates cytosolic phospholipase A(2) activity and the expression of cyclooxygenase-2 through different mechanisms in mouse keratinocytes

Anti-inflammatory, healing and antiophidic potential of Jatropha mollissima (Pohl) Baill. (Euphorbiaceae): From popular use to pharmaceutical formulation in gel

Jatropha mollissima (Pohl) Baill. (Euphorbiaceae) is widely used in traditional medicine to treat inflammatory disorders. So, a topical gel containing the hydroethanolic extract of its leaves was developed and evaluated for its anti-inflammatory, wound healing, and antiophidic properties in mice. First, the chemical profile of different parts of the plant was characterized by liquid chromatography coupled to mass spectrometry (LC-MS) using molecular networking. In the leaf extract, 11 compounds were characterized, with a particular emphasis on the identification of flavonoids. The gel efficiently inhibited carrageenan-induced paw edema, as well as acute and chronic croton oil-induced ear edema models, thereby reducing inflammatory and oxidative parameters in inflamed tissues. Besides anti-inflammatory activity, the herbal gel showed significant wound healing activity. The edematogenic, hemorrhagic and dermonecrotic activities induced by Bothrops jararaca snake venom were effectively inhibited by the treatment with J. mollissima gel. The association with the herbal gel improved in up to 90% the efficacy of commercial snake antivenom in reduce venom-induced edema. Additionally, while antivenom was not able to inhibit venom-induced dermonecrosis, treatment with herbal gel reduced in 55% the dermonocrotic halo produced. These results demonstrate the pharmacological potential of the herbal gel containing J. mollissima extract, which could be a strong candidate for the development of herbal products that can be used to complement the current antivenom therapy against snake venom local toxicity.

Fat of the Gut: Epithelial Phospholipids in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD) comprise a distinct set of clinical symptoms resulting from chronic inflammation within the gastrointestinal (GI) tract. Despite the significant progress in understanding the etiology and development of treatment strategies, IBD remain incurable for thousands of patients. Metabolic deregulation is indicative of IBD, including substantial shifts in lipid metabolism. Recent data showed that changes in some phospholipids are very common in IBD patients. For instance, phosphatidylcholine (PC)/phosphatidylethanolamine (PE) and lysophosphatidylcholine (LPC)/PC ratios are associated with the severity of the inflammatory process. Composition of phospholipids also changes upon IBD towards an increase in arachidonic acid and a decrease in linoleic and a-linolenic acid levels. Moreover, an increase in certain phospholipid metabolites, such as lysophosphatidylcholine, sphingosine-1-phosphate and ceramide, can result in enhanced intestinal inflammation, malignancy, apoptosis or necroptosis. Because some phospholipids are associated with pathogenesis of IBD, they may provide a basis for new strategies to treat IBD. Current attempts are aimed at controlling phospholipid and fatty acid levels through the diet or via pharmacological manipulation of lipid metabolism.

Anti-Inflammatory Comparison of Melatonin and Its Bromobenzoylamide Derivatives in Lipopolysaccharide (LPS)-Induced RAW 264.7 Cells and Croton Oil-Induced Mice Ear Edema

The pineal gland is a neuroendocrine organ that plays an important role in anti-inflammation through the hormone melatonin. The anti-inflammatory effects of melatonin and its derivatives have been reported in both in vitro and in vivo models. Our previous study reported the potent antioxidant and neuroprotective activities of bromobenzoylamide substituted melatonin. In silico analysis successfully predicted that melatonin bromobenzoylamid derivatives were protected from metabolism by CYP2A1, which is a key enzyme of the melatonin metabolism process. Therefore, the anti-inflammatory activities of melatonin and its bromobenzoylamide derivatives BBM and EBM were investigated in LPS-induced RAW 264.7 macrophages and croton oil-induced ear edema in mice. The experiments showed that BBM and EBM significantly reduced production of the inflammatory mediators interleukin-6 (IL-6), prostaglandin E2 (PGE₂), and nitric oxide (NO) in a dose-dependent manner, but only slightly affected TNF-α in LPS-induced RAW 264.7 macrophages. This suggests that modifying melatonin at either the N1-position or the N-acetyl side chain affected production of NO, PGE₂ and IL-6 in in vitro model. In the croton oil-induced mouse ear edema model, BBM, significantly decreased ear edema thickness at 2-4 h. It leads to conclude that bromobenzoylamide derivatives of melatonin may be one of the potential candidates for a new type of anti-inflammatory agent.

Anti-inflammatory and antinociceptive activity profile of a new lead compound - LQFM219

LQFM219 is a molecule designed from celecoxibe (COX-2 inhibitor) and darbufelone (inhibitor of COX-2 and 5-LOX) lead compounds through a molecular hybridisation strategy. Therefore, this work aimed to investigate the antinociceptive and anti-inflammatory activities of this new hybrid compound. The acute oral systemic toxicity of LQFM219 was evaluated via the neutral red uptake assay. Acetic acid-induced abdominal writhing and CFA-induced mechanical hyperalgesia were performed to evaluate the antinociceptive activity, and the anti-oedematogenic activity was studied by CFA-induced paw oedema and croton oil-induced ear oedema. Moreover, the acute anti-inflammatory activity was determined by carrageenan-induced pleurisy. In addition, cell migration, myeloperoxidase enzyme activity, and TNF-α and IL-1β levels were determined in pleural exudate. Moreover, a redox assay was conducted using electroanalytical and DPPH methods. The results demonstrated that LQFM219 was classified as GHS category 4, and it showed better free radical scavenger activity compared to BHT. Besides, LQFM219 decreased the number of writhings induced by acetic acid and the response to the mechanical stimulus in the CFA-induced mechanical hyperalgesia test. Furthermore, LQFM219 reduced oedema formation, cell migration, and IL-1β and TNF-α levels in the pleural cavity and inhibited myeloperoxidase enzyme activity. Thus, our study provides that the new pyrazole derivative, LQFM219, demonstrated low toxicity, antinociceptive and anti-inflammatory potential in vitro and in vivo.

Vincetoxicum arnottianum ameliorate inflammation by suppressing oxidative stress and pro-inflammatory mediators in rat

ETHNOPHARMACOLOGICAL RELEVANCE

Aerial parts of Vincetoxicum arnottianum (Wight) Wight (Family Apocynaceae) are used by local communities for inflammation, healing of wound and injuries and also for urticaria.

AIM OF STUDY

Extract/fractions of V. arnottianum were evaluated for potential anti-inflammatory activity in rat.

METHODS

Methanol extract of aerial parts of V. arnottianum (VAM) was partitioned on polarity for n-hexane (VAH), ethyl acetate (VAE), butanol (VAB) and aqueous (VAA) fractions. The extract/fractions were evaluated during in vitro assay for protection against heat induced protein denaturation and Carrageenan induced paw inflammation in rat. VAM and VAE were evaluated for anti-inflammatory potential against formalin and Freund's complete adjuvant (FCA) induced inflammation in paw of rat while croton oil induced inflammation in ear of rat, respectively. The level of inflammatory mediators; IL-17, IL-1β, IL-6, TNF-α and nitric oxide (NO) was estimated in serum of rat.

RESULTS

All the extract/fractions used in this study exhibited anti-inflammatory activity. However, VAE (300 mg/kg) exhibited potential anti-inflammatory activity in carrageenan (78.06 ± 4.6%), formalin (54.71 ± 0.34%) and croton oil (73.12 ± 1.9%) induced edema in rat. In FCA induced inflammation model VAM and VAE showed admiring proficiencies against alteration of body weight and organ weight indices, paw edema and histological studies. In serum increased level of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-17) and NO during adjuvant-induced inflammation were more efficiently restored with VAE treatment to rat. Presence of polyphenolics; rutin, gallic acid, caffeic acid, apigenin, myricetin and quercetin was indicated in VAE.

CONCLUSION

The results suggest the presence of anti-inflammatory constituents in V. arnottianum.

Phytochemical screening and anti-inflammatory properties of Algerian Hertia cheirifolia methanol extract

CONTEXT

Hertia cheirifolia L. (Asteraceae) is traditionally used in Northern Africa to treat various inflammatory infections. However, few studies on this plant have been reported.

OBJECTIVE

The anti-inflammatory activity of methanol extract of H. cheirifolia leaves was investigated using different experimental models.

MATERIALS AND METHODS

Phytochemical analysis was performed to determine phenolic compounds. Acute toxicity of the extract (2000 mg/kg) was examined in Swiss albino mice for 14 days, before croton oil-induced ear oedema in mice, carrageenan-induced paw oedema in Swiss albino rats, cotton pellet-induced granuloma in rats and carrageenan-induced air pouch in mice were conducted. The IL-1β and TNF-α release from concanavalin A-stimulated monocytes was measured by ELISA.

RESULTS

Methanol extract of H. cheirifolia is rich in polyphenols and flavonoids. Cinnamic acid and rutin represent the major constituents. Methanol extract up to 2000 mg/kg did not produce any toxic effects. Topical application of 2 mg/ear of the extract produced 78.7% of inhibition on ear swilling. Oral pre-treatment of rats with 200 and 400 mg/kg of the extract inhibited paw oedema by 70% and 89%, respectively. At 200 mg/kg, granuloma dry and wet weights were reduced by 41.85% and 61.72%, respectively. Moreover, the treatment with methanol extract at 1 mg/kg exerted 62.7% of inhibition on leucocytes migrated into the ear pouch. TNF-α and IL-1β release was reduced by 69% and 78%, respectively, with 1 μg/mL of the extract.

CONCLUSION

Methanol extract of H. cheirifolia possesses a strong anti-inflammatory activity and may be considered an interesting source of effective anti-inflammatory compounds.

MET signaling in keratinocytes activates EGFR and initiates squamous carcinogenesis

The receptor tyrosine kinase MET is abundant in many human squamous cell carcinomas (SCCs), but its functional significance in tumorigenesis is not clear. We found that the incidence of carcinogen-induced skin squamous tumors was substantially increased in transgenic MT-HGF (mouse metallothionein-hepatocyte growth factor) mice, which have increased abundance of the MET ligand HGF. Squamous tumors also erupted spontaneously on the skin of MT-HGF mice that were promoted by wounding or the application of 12-O-tetradecanoylphorbol 13-acetate, an activator of protein kinase C. Carcinogen-initiated tumors had Ras mutations, but spontaneous tumors did not. Cultured keratinocytes from MT-HGF mice and oncogenic RAS-transduced keratinocytes shared phenotypic and biochemical features of initiation that were dependent on autocrine activation of epidermal growth factor receptor (EGFR) through increased synthesis and release of EGFR ligands, which was mediated by the kinase SRC, the pseudoproteases iRhom1 and iRhom2, and the metallopeptidase ADAM17. Pharmacological inhibition of EGFR caused the regression of MT-HGF squamous tumors that developed spontaneously in orthografts of MT-HGF keratinocytes combined with dermal fibroblasts and implanted onto syngeneic mice. The global gene expression profile in MET-transformed keratinocytes was highly concordant with that in RAS-transformed keratinocytes, and a core RAS/MET coexpression network was activated in precancerous and cancerous human skin lesions. Tissue arrays revealed that many human skin SCCs have abundant HGF at both the transcript and protein levels. Thus, through the activation of EGFR, MET activation parallels a RAS pathway to contribute to human and mouse cutaneous cancers.

Structural optimization of 10-methyl-aplog-1, a simplified analog of debromoaplysiatoxin, as an anticancer lead

Aplog-1 is a simplified analog of debromoaplysiatoxin (DAT) with potent tumor-promoting and proinflammatory activities. Aplog-1 and DAT exhibited anti-proliferative activities against several human cancer cell lines, whereas aplog-1 did not have tumor-promoting nor proinflammatory activities. We have recently found 10-methyl-aplog-1 (1) to have strong anti-proliferative activity compared with aplog-1. To further investigate the structural factors involved in the tumor-promoting, proinflammatory, and anti-proliferative activities, two dimethyl derivatives of aplog-1 (2, 3) were synthesized, where two methyl groups were installed at positions 4 and 10 or 10 and 12. 10,12-Dimethyl-aplog-1 (2) had stronger inhibitory effects on the growth of several human cancer cell lines than 1 and DAT, but exhibited no tumor-promoting and proinflammatory activities. In contrast, 4,10-dimethyl-aplog-1 (3) displayed weak tumor-promoting and proinflammatory activities along with anti-proliferative activity similar to that of 1 and DAT. Compound 2 would be the optimized seed for anticancer drugs among the simplified analogs of DAT.

Chemopreventive effect of a novel, selective TACE inhibitor on DMBA- and TPA-induced skin carcinogenesis

Abstract Context: Tumor necrosis factor (TNF)-α, a potent proinflammatory cytokine, plays a major role in the pathogenesis of cancer. TNF-α converting enzyme (TACE) mediates processing and release of biologically active TNF-α.

OBJECTIVE

We aimed to investigate the effect of a novel, selective TACE inhibitor (compound 11p) on skin inflammation and associated tumorigenesis in mice.

METHODS

Skin edema was induced in mice by dermal application 12-O-tetradecanoylphorbol-13-acetate (TPA) solution in acetone on to the ear and the effect of post-treatment of compound 11p (topical application) was evaluated. Edema and inflammation was assessed by measuring ear thickness, weight of skin punch and cytokine levels. Skin cancer in mice was initiated by single topical application of 7,12-dimethylbenz[a]anthracene (DMBA) and promoted by repeated TPA application for 20 weeks. The effect of compound 11p on papilloma incidence and multiplicity was evaluated.

RESULTS

Treatment with compound 11p strongly suppressed TPA-induced elevation in skin thickness and weight. A dose-dependent suppression in TPA-mediated TNF-α, IL-6, IFN-γ, IL-17 and PGE2 levels which was associated with a decrease in infiltration of inflammatory cells was also observed with the treatment. Moreover, compound 11p treatment delayed the onset, markedly reduced the papilloma incidence and multiplicity persuaded by DMBA and TPA.

DISCUSSION AND CONCLUSION

These findings suggest that selective blockade of TACE suppresses TPA-induced epidermal hyperplasia, inflammatory cell infiltration and cytokine level. Inhibition of inflammatory events related to tumor growth might have led to the anti-tumor effect in mouse skin cancer model induced by DMBA and TPA.

p50-associated COX-2 extragenic RNA (PACER) activates COX-2 gene expression by occluding repressive NF-κB complexes

Deregulated expression of COX-2 has been causally linked to development, progression, and outcome of several types of human cancer. We describe a novel fundamental level of transcriptional control of COX-2 expression. Using primary human mammary epithelial cells and monocyte/macrophage cell lines, we show that the chromatin boundary/insulator factor CTCF establishes an open chromatin domain and induces expression of a long non-coding RNA within the upstream promoter region of COX-2. Upon induction of COX-2 expression, the lncRNA associates with p50, a repressive subunit of NF-κB, and occludes it from the COX-2 promoter, potentially facilitating interaction with activation-competent NF-κB p65/p50 dimers. This enables recruitment of the p300 histone acetyltransferase, a domain-wide increase in histone acetylation and assembly of RNA Polymerase II initiation complexes. Our findings reveal an unexpected mechanism of gene control by lncRNA-mediated repressor occlusion and identify the COX-2-lncRNA, PACER, as a new potential target for COX-2-modulation in inflammation and cancer.

DOI:http://dx.doi.org/10.7554/eLife.01776.001

To produce a protein a cell must first transcribe the DNA in a gene to make a messenger RNA molecule, which is then translated to make the protein. However, cells also produce other types of RNA molecules which do not become proteins. MicroRNAs, for example, regulate the expression of genes as proteins, while the role of other RNA molecules called long non-coding RNAs (lncRNAs) is not well understood.

Now Krawczyk and Emerson have found an lncRNA that controls a gene called COX-2 that is often implicated in breast, colon, prostate, and lung cancer. This RNA molecule, which is called PACER, originates near the start of the COX-2 gene, but it cannot be messenger RNA because it does not contain the instructions to make the COX-2 protein, and it is too long to be a microRNA. Further experiments showed that the newly discovered lncRNA activates the expression of the COX-2 gene.

Krawczyk and Emerson found that PACER attracts enzymes that spotlight genes that need to be activated, thus increasing the transcription of these genes to make messenger RNA. Genes can also be switched on and off by various molecules binding to nearby DNA, and PACER encourages the activation of COX-2 by keeping away the molecules that might switch it off.

In addition to shedding new light on the role of lncRNAs, these results suggest that PACER could be a suitable therapeutic target in cancers that involve the COX-2 gene.

DOI:http://dx.doi.org/10.7554/eLife.01776.002

Topical anti-inflammatory effect of Caryocar coriaceum Wittm. (Caryocaraceae) fruit pulp fixed oil on mice ear edema induced by different irritant agents

AIM OF THE STUDY

Caryocar coriaceum Wittm. fruit pulp fixed oil (CCFO) has been widely employed by communities from Brazil Northeastern in the treatment of skin inflammation, respiratory affections, wound healing and muscle pain. In this study, we evaluated the topical effect of CCFO against different irritant agents in vivo, in order to verify its antiedematous effect as well to unravel its tentative mechanisms of action.

MATERIALS AND METHODS

CCFO was obtained from Caryocar coriaceum fruits using ethyl acetate as solvent. Ear edema provoked by the application of Croton oil (single and multiple applications), arachidonic acid (AA), capsaicin, phenol and histamine to Swiss mice was used to evaluate the topical anti-inflammatory effect of CCFO. Histological analysis from mice ears sensitized with Croton oil and AA single application was also performed.

RESULTS

Crude CCFO (20μL/ear) demonstrated significant topical antiedematous effect against Croton oil single (inhibition of 32.0%; P<0.05) and multiple (41.4% after 9 days, P<0.001) applications, AA (inhibition of 49.7%; P<0.01) and phenol (inhibition of 38.8%; P<0.001). In contrast, CCFO did not antagonize the edema caused by topical treatment with capsaicin and histamine when compared to control group (P>0.05). Histological analysis also revealed that CCFO was able to reduce the edema and the influx of inflammatory cells in mice ears sensitized with Croton oil and AA.

CONCLUSIONS

CCFO exhibited a similar profile of topical anti-inflammatory activity to that of drugs that classically modulate the production of arachidonic acid metabolites. The study also indicates the potential application of CCFO as an important herbal medicine to be used against skin inflammatory diseases.

Chlorogenic acids from Tithonia diversifolia demonstrate better anti-inflammatory effect than indomethacin and its sesquiterpene lactones

ETHNOPHARMACOLOGICAL RELEVANCE

T. diversifolia (Hemsl.) A. Gray (Asteraceae) has been used in the traditional medicine in several countries as anti-inflammatory and against other illnesses. It is important to evaluate the anti-inflammatory activity of extracts from the leaves of this species, including an infusion, to identify the main constituents of the extracts, observe their effects and correlate them with the anti-inflammatory activity.

MATERIALS AND METHODS

An infusion, a leaf rinse extract (LRE) and a polar extract from the rinsed leaves (PE) were obtained and analysed by HPLC-UV-DAD and infrared spectroscopy. The major compounds of these extracts were quantified. The three obtained extracts were evaluated for their anti-inflammatory activities using the paw oedema and croton oil ear oedema assays in mice. Furthermore, neutrophil migration was measured by evaluating myeloperoxidase activity.

RESULTS

The PE consists primarily of chlorogenic acids (CAs) and lacks sesquiterpene lactones (STLs). The LRE is rich in STLs and includes a few flavonoids. The infusion is chemically similar to the PE but also contains very low amounts of STLs. The PE and LRE have better mechanisms of action than non-steroidal anti-inflammatory drugs (NSAIDs). Unlike NSAIDs, both the PE and LRE inhibit oedema and neutrophil migration. The pool of CAs from the PE of T. diversifolia has an additional mechanism of action, and its anti-inflammatory effect was greater than what is described in the literature for this class of compounds using the same evaluation models. The similar chemical compositions observed for the infusion and the PE, contrasted with the different activities observed, suggests the presence of antagonist compounds produced during the extraction procedure (infusion); the infusion did not inhibit oedema, however it inhibited neutrophil migration. It suggests that although the great majority of plants present CAs, the category of anti-inflammatory effect of their extracts depends on a suitable pool of compounds and an absence of antagonists, among other factors.

CONCLUSIONS

CAs from T. diversifolia comprise a good pool of anti-inflammatory compounds with better activity mechanisms than NSAIDs, other active compounds from the leaf extracts (STLs and flavonoids) and CAs from other plant sources. Thus, the PE of T. diversifolia has high potential for the development of new anti-inflammatory phytomedicines. The infusion probably contains antagonists, and therefore it can be useful to treat inflammation processes where neutrophil recruitment is involved and oedema is not.

Neutrophil gelatinase-associated lipocalin in gastric carcinoma cells and its induction by TPA are controlled by C/EBPβ

Neutrophil gelatinase-associated lipocalin (NGAL) expression has been found to be upregulated in a variety of tumors, but the mechanism of NGAL elevation in gastric carcinoma remains unknown. Here, immunohistochemistry was applied to analyze NGAL expression in gastric carcinoma patients. Reverse transcription PCR, Western blot, and enzyme-linked immunosorbent assay (ELISA) were performed to evaluate NGAL mRNA and protein levels before and after 12-O-tetradecanoylphorbol-13-acetate (TPA) induction. Luciferase reporter assay was carried out to identify the core cis element in NGAL promoter. The binding ability and specificity of transcription factors were analyzed by electrophoretic mobility-shift assay (EMSA) and chromatin immunoprecipitation (ChIP), respectively. Results showed that NGAL was overexpressed in gastric tumor tissues. Gastric cancer cells treated with TPA resulted in the transactivation of NGAL promoter and the upregulation of its mRNA and protein levels. We identified the -110 to -79 sequence segment upstream from the transcription initiation site of NGAL as a TPA responsive element (TRE) and confirmed that C/EBPβ was able to bind to the -87 to -79 segment. Forced expression of C/EBPβ significantly increased the promoter activity of NGAL as well as its mRNA level. These results suggest that NGAL is overexpressed in gastric cancer, the binding of C/EBPβ to the TRE of its gene promoter mediates its TPA-induced overexpression in gastric carcinoma cells.

Anti-inflammatory effect of crude extract and isolated compounds from Baccharis illinita DC in acute skin inflammation

ETHNOPHARMACOLOGYCAL RELEVANCE: The tea from the leaves of Baccharis illinita DC (Asteraceae family) is commonly used by the population as anti-inflammatory (including topically), protective gastric and anti-infectious. However, no studies have been done with this species to confirm its topical anti-inflammatory action.

AIM

This study evaluated he topical effects of crude extract of leaves (CE) and its active constituents in 12-O-tetradecanoylphorbol acetate (TPA)-induced ear oedema.

METHODOLOGY

CE and compounds effects were tested in commonly used models of TPA-, arachidonic acid (AA)- and capsaicin-ear oedema. Polymorphonuclear (PMN) cell migration was evaluated by mieloperoxidase and analyzed histologically.

RESULTS

CE (0.1-1 mg/ear) caused a dose-related inhibition of TPA-induced ear oedema and PMN influx similarly to that produced by topical application of the steroidal anti-inflammatory drug dexamethasone. The active constituents of the AcOEt fraction kaurenoic acid, alpha-spinasterol, oleanolic acid and baurenol also inhibited TPA-induced ear edema. Histological analysis of the ear of CE-treated animals confirmed the reduction of edema and of PMN infiltration. Both CE and the nosteroidal anti-inflammatory drug indomethacin inhibited the AA-induced ear oedema, but did not change capsaicin-induced oedema.

CONCLUSION

These results indicate that the CE and the active constituents have a topical anti-inflammatory effect and the possible mechanisms for the pharmacological effects are discussed.

Role of protein kinase C in regulation of Na+- and K +-dependent ATPase activity and pump function in corneal endothelial cells

PURPOSE

Na+- and K+-dependent ATPase (Na,K-ATPase) plays an important role in the pump function of the corneal endothelium. We investigated the possible role of protein kinase C (PKC) in regulation of Na,K-ATPase activity and pump function in corneal endothelial cells.

METHODS

Confluent monolayers of mouse corneal endothelial cells were exposed to phorbol 12,13-dibutyrate (PDBu) to induce activation of PKC. ATPase activity of the cells was evaluated by using ammonium molybdate in spectrophotometric measurement of phosphate released from ATP, with Na,K-ATPase activity being defined as the portion of total ATPase activity sensitive to ouabain. Pump function of the cells was measured with a Ussing chamber, with the pump function attributable to Na,K-ATPase activity being defined as the portion of the total short-circuit current sensitive to ouabain.

RESULTS

PDBu (10(-7) M) increased the Na,K-ATPase activity and pump function of the cultured cells. These effects of PDBu were potentiated by the cyclooxygenase inhibitor indomethacin and the cytochrome P(450) inhibitor resorufin and were blocked by okadaic acid, an inhibitor of protein phosphatases 1 and 2A.

CONCLUSIONS

Our results suggest that PKC bidirectionally regulates Na,K-ATPase activity in mouse corneal endothelial cells: it inhibits Na,K-ATPase activity in a cyclooxygenase- and cytochrome P(450)-dependent manner, whereas it stimulates such activity by activating protein phosphatases 1 or 2A.

Chloroform extract of cigarette smoke induces proliferation of human esophageal squamous-cell carcinoma cells: modulation by beta-adrenoceptors

The present study aimed to delineate the actions of cigarette smoke extracts on esophageal squamous-cell carcinoma cell growth in vitro. Both chloroform- and ethanol-extracts from cigarette smoke stimulated human esophageal squamous carcinoma EC109 cell proliferation. Chloroform- and ethanol-extracts also upregulated beta-adrenoceptors expression in EC109 cells. Cyclo-oxygenase-2 (COX-2) expression was increased by chloroform-extract. The stimulatory actions of chloroform-extract on cell proliferation and COX-2 expression were abolished by beta(1)- and beta(2)-adrenoceptor selective antagonists, implicating that COX-2 was downstream to the beta-adrenoceptors. Collectively, the promoting action of chloroform-extract from cigarette smoke on esophageal squamous-cell carcinoma cell proliferation is beta-adrenoceptor- and COX-2-dependent.

Estradiol activates mast cells via a non-genomic estrogen receptor-alpha and calcium influx

BACKGROUND

Allergic airway diseases are more common in females than in males during early adulthood. A relationship between female hormones and asthma prevalence and severity has been suggested, but the cellular and molecular mechanisms are not understood.

OBJECTIVE

To elucidate the mechanism(s) by which estrogens enhance the synthesis and release of mediators of acute hypersensitivity.

METHODS

Two mast cell/basophil cell lines (RBL-2H3 and HMC-1) and primary cultures of bone marrow derived mast cells, all of which naturally express estrogen receptor-alpha, were examined. Cells were incubated with physiological concentrations of 17-beta-estradiol with and without IgE and allergens. Intracellular Ca(2+) concentrations and the release of beta-hexosaminidase and leukotriene C(4) were quantified.

RESULTS

Estradiol alone induced partial release of the preformed, granular protein beta-hexosaminidase from RBL-2H3, BMMC and HMC-1, but not from BMMC derived from estrogen receptor-alpha knock-out mice. The newly synthesized LTC(4) was also released from RBL-2H3. Estradiol also enhanced IgE-induced degranulation and potentiated LTC(4) production. Intracellular Ca(2+) concentration increased prior to and in parallel with mediator release. Estrogen receptor antagonists or Ca(2+) chelation inhibited these estrogenic effects.

CONCLUSION

Binding of physiological concentrations of estradiol to a membrane estrogen receptor-alpha initiates a rapid onset and progressive influx of extracellular Ca(2+), which supports the synthesis and release of allergic mediators. Estradiol also enhances IgE-dependent mast cell activation, resulting in a shift of the allergen dose response.

p63 and p73, members of the p53 gene family, transactivate PKCδ

The p53 family comprises three genes that encode for p53, p63 and p73. These genes have a significant degree of sequence homology, especially in the central sequence-specific DNA-binding domain. The high homology among the three DNA-binding domains indicates that these transcription factors have identical residues interacting with DNA, and thus potentially can recognize the same transcriptional targets. In this study, we demonstrate that PKCdelta is induced by p63 and p73 in Saos2 cells. The putative human PKCdelta promoter harbours three p53-like binding sites (RE I, RE II, RE III). In order to confirm the transactivation of PKCdelta by p53 family members, we performed transcription assays using the entire or selected regions of the promoter upstream of a luciferase reporter gene. The results obtained demonstrated that, at least in vitro, the p53 family members tested (TAp63alpha, TAp73alpha, DeltaNp63alpha, but not DeltaNp73alpha) were able to drive transcription from the PKCdelta promoter.

Amyloid β peptide (25–35) activates protein kinase C leading to cyclooxygenase-2 induction and prostaglandin E2 release in primary midbrain astrocytes

Prostaglandins (PGs) are generated by the enzymatic activity of cyclooxygenase-1 and -2 (COX-1/2) and modulate several functions in the CNS such as the generation of fever, the sleep/wake cycle, and the perception of pain. Moreover, the induction of COX-2 and the generation of PGs has been linked to neuroinflammatory aspects of Alzheimer's disease (AD). Non-steroidal anti-inflammatory drugs (NSAIDs) that block COX enzymatic activity have been shown to reduce the incidence of AD in various epidemiological studies. While several reports investigated the expression of COX-2 in neurons and microglia, expression of COX-2 in astroglial cells has not been investigated in detail. Here we show that amyloid beta peptide 25-35 (Abeta(25-35)) induces COX-2 mRNA and protein synthesis and a subsequent release of prostaglandin E(2) (PGE(2)) in primary midbrain astrocytes. We further demonstrate that protein kinase C (PKC) is involved in Abeta(25-35)-induced COX-2/PGE(2) synthesis. PKC-inhibitors prevent Abeta(25-35)-induced COX-2 and PGE(2) synthesis. Furthermore Abeta(25-35) rapidly induces the phosphorylation and enzymatic activation of PKC in primary rat midbrain glial cells and in primary human astrocytes from post mortem tissue. Our data suggest that the PKC isoforms alpha and/or beta are most probably involved in Abeta(25-35)-induced expression of COX-2 in midbrain astrocytes. The potential role of astroglial cells in the phagocytosis of amyloid and the involvement of PGs in this process suggests that a modulation of PGs synthesis may be a putative target in the prevention of amyloid deposition.

Cocoa polyphenols inhibit phorbol ester-induced superoxide anion formation in cultured HL-60 cells and expression of cyclooxygenase-2 and activation of NF-kappaB and MAPKs in mouse skin in vivo

We investigated the antioxidant and antiinflammatory activities of a flavonoid-rich polyphenolic fraction of cocoa. Cocoa polyphenol (CP) was fractionated from commercial cocoa powder and contained 468 mg/g of gallic acid-equivalent phenolics and 413 mg/g epicatechin-equivalent flavonoids. CP exhibited a dose-dependent free radical-scavenging activity as determined by both 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2'-diphenyl-1-picrylhydrazyl radical scavenging assays. CP also dose-dependently inhibited xanthine oxidase activity and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced superoxide-anion generation in cultured human promyeolcytic leukemia HL-60 cells. Oral administering of CP (4, 20, 40, and 200 mg/kg body weight) to ICR mice 1 h prior to TPA (10 nmol) inhibited ear edema at 5 h in a dose-dependent manner. The levels of COX-2 expression induced in mouse skin after 4-h treatment with topical TPA (10 nmol) was also diminished significantly by pretreating CP (40 or 200 mg/kg) for 30 min. CP at the same doses inhibited TPA-induced nuclear translocation of p65 and subsequent DNA binding of NF-kappaB at 1 h by blocking the degradation of IkappaBalpha in mouse skin. Moreover, phosphorylation of p38 mitogen-activated protein kinase in ICR mouse skin, measured 4 h after TPA treatment, was suppressed by oral pretreatment of CP (40 or 200 mg/kg). Although extracellular signal-regulated protein kinase 1/2 phosphorylation was unaffected, CP inhibited the catalytic activity of extracellular signal-regulated protein kinase 1/2 in TPA-stimulated mouse skin. Since cellular proinflammatory and prooxidant states are closely linked to tumor promotion, the antioxidant and antiinflammatory properties of CP may constitute the basis of possible antitumor promoting effects of this phytochemical.

Involvement of tumor necrosis factor (TNF)-α in phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin edema in mice

Topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) to mouse ear induced a prolonged skin inflammation. Histological analysis revealed that the early stage (approximately 3 h) and later stage (6-24 h) of the skin reaction are characterized by dermal edema and cell accumulation, respectively. Topical application with TPA also induced increase in the level of TNF-alpha and prostagrandin E2 (PGE2) at the application site. The increase of TNF-alpha was transient with a peak at approximately 5 h, followed by a gradual elevation of PGE2 level in the skin. An in vitro study with human keratinocytes as well as immunohistochemical analysis suggested that TNF-alpha induction in the skin might be produced by epidermis treated with TPA. Administration of a cyclooxygenase inhibitor indomethacin inhibited the later stage of the TPA-induced edema. In contrast, TNF-alpha antagonist etanercept inhibited exclusively the early stage of the reaction. Taken together, these data demonstrate that the prolongation of the skin inflammation induced by TPA may be due to the sequential production of proinflammatory mediators such as eicosanoids and cytokines, and show for the first time the importance of TNF-alpha in the TPA-induced dermatitis especially at the stage where dermal edema is significant.

Estrogen induces phospholipase A2 activation through ERK1/2 to mobilize intracellular calcium in MCF-7 cells

The principal secreted estrogen, 17beta-estradiol rapidly activates signaling cascades that regulate important physiological processes including ion transport across membranes, cytosolic pH and cell proliferation. These effects have been extensively studied in the MCF-7 estrogen-responsive human breast carcinoma cell line. Here, we demonstrate that a physiological concentration of 17beta-estradiol caused a rapid, synchronous and transient increase in intracellular calcium concentration in a confluent monolayer of MCF-7 cells 2-3 min after treatment. This response was abolished when cells were pre-incubated with the phospholipase A(2) (PLA(2)) inhibitor quinacrine or with the cyclooxygenase inhibitor indomethacin. The translocation of GFP-cPLA(2)alpha to perinuclear membranes occurred 1-2 min after 17beta-estradiol treatment; this translocation was concurrent with the transient phosphorylation of cPLA(2)alpha at serine residue 505. The phosphorylation and translocation of cPLA(2) were sensitive to inhibition of the extracellular signal regulated kinase (ERK) signaling cascade and occurred simultaneously with a transient activation of ERK. The phosphorylation of cPLA(2) could be stimulated by membrane impermeable 17beta-estradiol conjugated to bovine serum albumen and was blocked by an antagonist of the classical estrogen receptor. Here we show, for the first time, that PLA(2) and the eicosanoid biosynthetic pathway are involved in the 17beta-estradiol induced rapid calcium responses of breast cancer cells.

A downstream role for protein kinase Calpha in the cytosolic phospholipase A2-dependent protective signalling mediated by peroxynitrite in U937 cells

Exposure to an otherwise non-toxic concentration of peroxynitrite (ONOO-) promotes toxicity in U937 cells supplemented with pharmacological inhibitors of protein kinase C (PKC). This effect is not associated with enhanced formation of H2O2 and is in fact causally linked to inhibition of the cytoprotective signalling driven by endogenous arachidonic acid (AA). The outcome of various approaches using PKC or phospholipase A2 inhibitors, cytosolic phospholipase A2 or PKCalpha antisense-oligonucleotide-transfected cells and supplementation with exogenous AA or tetradecanoylphorbol acetate, as well as PKC down-regulated cells, indicated that ONOO- promotes AA-dependent cytosol to membrane translocation of PKCalpha, an event critical for the cytoprotective signalling under investigation. Evidence for a similar mechanism regulating survival of human monocytes exposed to ONOO- is also presented. These results, along with our previous work on this topic, contribute to the definition of the mechanism whereby monocytes survive to ONOO- in inflamed tissues.

Signal transduction network leading to COX-2 Induction: a road map in search of cancer chemopreventives

Cancer is still a major global health concern even after an everlasting strive in conquering this dread disease. Emphasis is now given to chemoprevention to reduce the risk of cancer and also to improve the quality of life among cancer afflicted individuals. Recent progress in molecular biology of cancer has identified key components of the cellular signaling network, whose functional abnormality results in undesired alterations in cellular homeostasis, creating a cellular microenvironment that favors premalignant and malignant transformation. Multiple lines of evidence suggest an elevated expression of cyclooxygenase-2 (COX-2) is causally linked to cancer. In response to oxidative/pro-inflammatory stimuli, turning on unusual signaling arrays mediated through diverse classes of kinases and transcription factors results in aberrant expression of COX-2. Population-based as well as laboratory studies have explored a broad spectrum of chemopreventive agents including selective COX-2 inhibitors and a wide variety of anti-inflammatory phytochemicals, which have been shown to target cellular signaling molecules as underlying mechanisms of chemoprevention. Thus, unraveling signaling pathways regulating aberrant COX-2 expression and targeted blocking of one or more components of those signal cascades may be exploited in searching chemopreventive agents in the future.

Targeting signal transduction pathways by chemopreventive agents

Cancer is a dynamic process that involves many complex factors, which may explain why a "magic bullet" cure for cancer has not been found. Death rates are still rising for many types of cancers, which possibly contributes to the increased interest in chemoprevention as an alternative approach to the control of cancer. This strategy for cancer control is based on the presumption that because cancer develops through a multi-step process, each step may be a prospective target for reversing or suppressing the process. Thus, the design and development of chemopreventive agents that act on specific and/or multiple molecular and cellular targets is gaining support as a rational approach to control cancer. Nutritional or dietary factors have attracted a great deal of interest because of their perceived ability to act as highly effective chemopreventive agents. They are professed as being generally safe and may have efficacy as chemopreventive agents by preventing or reversing premalignant lesions and/or reducing second primary tumor incidence. Many of these dietary compounds appear to act on multiple target signaling pathways. Some of the most interesting and well documented are resveratrol and components of tea, including EGCG, theaflavins and caffeine. This review will focus on recent work regarding three well-accepted cellular/molecular mechanisms that may at least partially explain the effectiveness of selected food factors, including those indicated above, as chemopreventive anti-promotion agents. These food compounds may act by: (1) inducing apoptosis in cancer cells; (2) inhibiting neoplastic transformation through the inhibition of AP-1 and/or NF-kappaB activation; and/or (3) suppressing COX-2 overexpression in cancer cells.

Signal transduction pathways regulating cyclooxygenase-2 expression: potential molecular targets for chemoprevention

Expression of cyclooxygenase-2 (COX-2) has been reported to be elevated in human colorectal adenocarcinoma and other tumors, including those of breast, cervical, prostate, and lung. Genetic knock-out or pharmacological inhibition of COX-2 has been shown to protect against experimentally-induced carcinogenesis. Results from epidemiological and laboratory studies indicate that regular intake of selective COX-2 inhibitors reduces the risk of several forms of human malignancies. Thus, it is conceivable that targeted inhibition of abnormally or improperly elevated COX-2 provides one of the most effective and promising strategies for cancer chemoprevention. The COX-2 promoter contains a TATA box and binding sites for several transcription factors including nuclear factor-kappaB (NF-kappaB), nuclear factor for interleukin-6/CCAAT enhancer-binding protein (NF-IL6/C/EBP) and cyclic AMP response element (CRE) binding protein. Upregulation of COX-2 is mediated by a variety of stimuli including tumor promoters, oncogenes, and growth factors. Stimulation of either protein kinase C (PKC) or Ras signaling enhances mitogen-activated protein kinase (MAPK) activity, which, in turn, activates transcription of cox-2. Celecoxib, the first US FDA approved selective COX-2 inhibitor, initially developed for the treatment of adult rheumatoid arthritis and osteoarthritis, has been reported to reduce the formation of polyps in patients with familial adenomatous polyposis. This COX-2 specific inhibitor also protects against experimentally-induced carcinogenesis, but the underlying molecular mechanisms are poorly understood. The present review covers the signal transduction pathways responsible for regulating COX-2 expression as novel molecular targets of chemopreventive agents with celecoxib as a specific example.

Hyaluronan-CD44 interaction with Rac1-dependent protein kinase N-gamma promotes phospholipase Cgamma1 activation, Ca(2+) signaling, and cortactin-cytoskeleton function leading to keratinocyte adhesion and differentiation

In this study we have investigated hyaluronan (HA)-CD44 interaction with protein kinase N-gamma (PKNgamma), a small GTPase (Rac1)-activated serine/threonine kinase in human keratinocytes. By using a variety of biochemical and molecular biological techniques, we have determined that CD44 and PKNgamma kinase (molecular mass approximately 120 kDa) are physically linked in vivo. The binding of HA to keratinocytes promotes PKNgamma kinase recruitment into a complex with CD44 and subsequently stimulates Rac1-mediated PKNgamma kinase activity. The Rac1-activated PKNgamma in turn increases threonine (but not serine) phosphorylation of phospholipase C (PLC) gamma1 and up-regulates PLCgamma1 activity leading to the onset of intracellular Ca(2+) mobilization. HA/CD44-activated Rac1-PKNgamma also phosphorylates the cytoskeletal protein, cortactin, at serine/threonine residues. The phosphorylation of cortactin by Rac1-PKNgamma attenuates its ability to cross-link filamentous actin in vitro. Further analyses indicate that the N-terminal antiparallel coiled-coil (ACC) domains of PKNgamma interact directly with Rac1 in a GTP-dependent manner. The binding of HA to CD44 induces PKNgamma association with endogenous Rac1 and its activity in keratinocytes. Transfection of keratinocytes with PKNgamma-ACCcDNA reduces HA-mediated recruitment of endogenous Rac1 to PKNgamma and blocks PKNgamma activity. These findings suggest that the PKNgamma-ACC fragment acts as a potent competitive inhibitor of endogenous Rac1 binding to PKNgamma in vivo. Most important, the PKNgamma-ACC fragment functions as a strong dominant-negative mutant that effectively inhibits HA/CD44-mediated PKNgamma phosphorylation of PLCgamma1 and cortactin as well as keratinocyte signaling (e.g. Ca(2+) mobilization and cortactin-actin binding) and cellular functioning (e.g. cell-cell adhesion and differentiation). Taken together, these findings strongly suggest that hyaluronan-CD44 interaction with Rac1-PKNgamma plays a pivotal role in PLCgamma1-regulated Ca(2+) signaling and cortactin-cytoskeleton function required for keratinocyte cell-cell adhesion and differentiation.

Cyclooxygenases in the skin: pharmacological and toxicological implications

Cyclooxygenase (COX), a prostaglandin-endoperoxide synthase (PTGS), catalyzes the formation of prostaglandins from arachidonic acid. Prostaglandins are lipid signaling mediators that play a central role in a broad range of diverse physiological and pathophysiological processes, including inflammation, reproduction, nocioception, and gastrointestinal protection. Inhibition of cyclooxygenase activity is the mechanism by which nonsteroidal antiinflammatory drugs (NSAIDS) exert their analgesic, antipyretic, antiinflammatory, and antithrombotic effects. COX is currently believed to exist in three isoforms. In this review, we provide a concise state-of-the-art description of the role of COX in pharmacology and toxicology of skin including its involvement in normal physiology, cutaneous inflammation, nociception, wound healing, and tumorigenesis. COX-dependent pathways influence keratinocyte differentiation, hair follicle development, and hair growth. The critical role of COX-2 in pathophysiology of skin is also addressed. COX-2 mediates inflammatory processes in skin, including inflammatory hyperalgesia and nociception, and administration of specific COX-2 inhibitors reduces edema, vascular permeability, and other markers of cutaneous inflammation. A number of studies in animal models and in humans show that COX-2 inhibitors possess cancer chemopreventive properties. Selective COX-2 inhibitors have a more favorable side-effect profile. Topical formulations of COX-2 inhibitors are being developed as a novel pharmacologic approach for the treatment of COX-2 mediated skin diseases.

Activation of cutaneous protein kinase C alpha induces keratinocyte apoptosis and intraepidermal inflammation by independent signaling pathways

Skin keratinocytes are major mediators of host immune responses. The skin is also a target for immunologically based inflammation in many pathological states. Activation of protein kinase C (PKC) can induce cutaneous inflammation, but the precise role of each of six cutaneous PKC isoforms (alpha, delta, epsilon, eta, zeta, mu) that regulate normal skin homeostasis or contribute to skin pathology has not been clarified. We generated transgenic mice that overexpress PKCalpha in the basal layer of the epidermis and the outer root sheath of hair follicles under the regulation of the bovine keratin 5 promoter. K5-PKCalpha transgenic mice exhibit severe intraepidermal neutrophilic inflammation and disruption of the epidermis and upper hair follicles when treated topically with 12-O-tetradecanoylphorbol-13-acetate (TPA). Both TPA and UVB cause apoptosis in transgenic skin, but only TPA evokes intraepidermal inflammation. TPA also induces apoptosis in cultured transgenic keratinocytes, and this is prevented by an AP-1 dominant-negative construct. However, inhibiting AP-1 in vivo does not abrogate intraepidermal inflammation. Transcripts for specific cytokines and chemokines are elevated in TPA-treated cultured transgenic keratinocytes, and conditioned culture medium from these cells promotes neutrophil migration in vitro. Chemokine expression and neutrophil migration are not diminished by inhibiting AP-1. Thus, PKCalpha activation induces keratinocyte apoptosis via an AP-1-dependent pathway and mediates chemokine induction and intraepidermal inflammation independently. This model system will be useful to define specific chemokines regulated by PKCalpha that promote intraepidermal neutrophilic inflammation, a condition that characterizes several human cutaneous diseases such as pustular psoriasis and acute generalized exanthematous pustulosis.

A Galphas protein-coupled membrane receptor, distinct from the classical oestrogen receptor, transduces rapid effects of oestradiol on [Ca2+]i in female rat distal colon

We examined the hypothesis whether rapid non-genomic effects of oestradiol (E2) on [Ca(2+)](i) are mediated via a membrane-located oestrogen receptor (ER) and further elucidated the signalling pathways involved in rapid non-genomic effects of E2 on [Ca(2+)](i) in distal colonic crypts. Basal [Ca(2+)](i) was significantly increased, within minutes, in response to physiological concentrations of E2. Oestradiol linked to bovine serum albumin (E2-BSA), which renders the E2 membrane impermeable, rapidly increased [Ca(2+)](i) suggesting mediation by a membrane surface receptor. A classical ER is not involved however, as no inhibition of either the E2 or E2-BSA [Ca(2+)](i) response was seen in the presence of the classical ER antagonist ICI 182,780. Treatment with the Galphas inhibitor cholera toxin abolished both E2 and E2-BSA induced Ca(2+) increases. In contrast, treatment with pertussis toxin, an inhibitor of Galphai and Galphao, had no inhibitory effect. Following subsequent additions of E2 and E2-BSA, no further increases in [Ca(2+)](i) were observed, indicating receptor desensitisation. The E2-induced increase in [Ca(2+)](i) was completely abolished by the PKCdelta-specific inhibitor rottlerin, whereas Go6976, an inhibitor of Ca(2+)-sensitive PKC isoforms, was without inhibitory effect. The phospholipase A2 antagonist, quinacrine, and the COX1 inhibitor, indomethacin, abolished the E2-induced increase in [Ca(2+)](i). MAP kinase activation is not involved in rapid stimulatory effects of E2 on [Ca(2+)](i) as the specific inhibitor PD98059 did not inhibit the E2 response. These results demonstrate that rapid E2-induced stimulation of [Ca(2+)](i), in femal rat distal colonic crypts, occurs via a CTx-sensitive Galphas-coupled membrane receptor distinct from the classical ER. PKCdelta and fatty acids are involved in the E2 signalling pathway. In contrast, PKCalpha and MAP kinase are not required.

Epidermal anti-Inflammatory properties of 5,11,14 20:3: effects on mouse ear edema, PGE2 levels in cultured keratinocytes, and PPAR activation

BACKGROUND

5,11,14 20:3 is similar to 20:4n-6 but lacks the internal Delta8 double bond essential for prostaglandin and eicosanoid synthesis. When previously fed to laboratory animals as a gymnosperm seed oil component it has shown anti-inflammatory properties.

RESULTS

Herein, topically applied Podocarpus nagi methyl esters (containing 26% 5,11,14 20:3) were incorporated into mouse ear phospholipids, reduced 20:4n-6, and reduced 20:4n-6- and TPA-induced mouse ear edema. Purified 5,11,14 20:3 was taken up by cultured human skin keratinocytes, reduced 20:4n-6, and reduced PGE2 levels dramatically. Purified 5,11,14 20:3 did not affect PPARalpha, PPARgamma, or PPARdelta transactivation.

CONCLUSIONS

Topical application of 5,11,14 20:3 to skin surfaces can thus reduce inflammatory processes, most likely by displacing 20:4n-6 from phospholipid pools and reducing downstream inflammatory products derived from 20:4n-6 such as PGE2 and leukotrienes. It could have potential use in treating clinical skin disorders resulting from overproduction of 20:4n-6-derived eicosanoid products.

Protein kinase C-epsilon mediates bradykinin-induced cyclooxygenase-2 expression in human airway smooth muscle cells

We previously reported that proinflammatory mediator bradykinin (BK) induces cyclooxygenase (COX)-2 expression in human airway smooth muscle (HASM), but the mechanism is unknown in any biological system. Here, we studied the role of specific protein kinase C (PKC) isozyme(s) in COX-2 expression. Among the eight PKC isozymes present in HASM cells, the Ca2+-independent PKC-delta and -epsilon and the Ca2+-dependent PKC-alpha and -betaI were translocated to the nucleus upon BK stimulation. BK-induced COX-2 expression and prostaglandin E2 (PGE2) accumulation were mimicked by the direct PKC activator phorbol 12-myristate 13-acetate (PMA) and inhibited by the broad spectrum PKC inhibitor bisindolylmaleimide I. However, the selective Ca2+-dependent PKC isozyme inhibitor Go 6976 had no effect. Furthermore, the membrane-permeable calcium chelator BAPTA-AM had no effect on BK-induced COX-2 expression and COX activity despite its inhibition of PGE2 accumulation, suggesting the involvement of Ca2+-independent PKC isozymes. Rottlerin, a PKC-delta inhibitor, also had no effect, likely implicating PKC-epsilon. BK-stimulated transcriptional activation of a COX-2 promoter reporter construct was enhanced by overexpression of wild-type PKC-epsilon and abolished by a dominant negative PKC-epsilon, but it was not affected by wild-type or dominant negative PKC-alpha or -delta. Collectively, our results demonstrate that PKC-e mediates BK-induced COX-2 expression in HASM cells.

Anti-tumor promoting potential of selected spice ingredients with antioxidative and anti-inflammatory activities: a short review

A wide variety of phenolic substances derived from spice possess potent antimutagenic and anticarcinogenic activities. Examples are curcumin, a yellow colouring agent, contained in turmeric (Curcuma longa L., Zingiberaceae), [6]-gingerol, a pungent ingredient present in ginger (Zingiber officinale Roscoe, Zingiberaceae) and capsaicin, a principal pungent principle of hot chili pepper (Capsicum annuum L, Solanaceae). The chemopreventive effects exerted by these phytochemicals are often associated with their antioxidative and anti-inflammatory activities. Cyclo-oxygenase-2 (COX-2) has been recognized as a molecular target of many chemopreventive as well as anti-inflammatory agents. Recent studies have shown that COX-2 is regulated by the eukaryotic transcription factor NF-kappaB. This short review summarizes the molecular mechanisms underlying chemopreventive effects of the aforementioned spice ingredients in terms of their effects on intracellular signaling cascades, particularly those involving NF-kappaB and mitogen-activated protein kinases.

Cyclooxygenase-2 expression in murine and human nonmelanoma skin cancers: implications for therapeutic approaches

Inflammatory stimuli result in the production of cutaneous eicosanoids, which are known to contribute to the process of tumor promotion. Cyclooxygenase (COX), the rate-limiting enzyme for the production of prostaglandins (PG) from arachidonic acid, exists in at least two isoforms, COX-1 and COX-2. COX-1 is constitutively expressed in most tissues and plays various physiological roles, whereas increased COX-2 expression is known to occur in several types of epithelial neoplasms. Enhanced PG synthesis is a potential contributing factor in UVB-induced nonmelanoma skin cancers (NMSC). Increased COX-2 staining occurs in murine skin neoplasms after chronic exposure to carcinogenic doses of UVB. In this study, immunohistochemical and Western blot analyses were employed to assess longitudinally COX-2 expression in a standard mouse UVB complete carcinogenesis protocol and in human basal cell carcinomas (BCC) and squamous cell carcinomas (SCC). During UVB irradiation of mice, COX-2 expression consistently increased in the hyperplastic skin, the benign papillomas and the SCC. COX-2 expression was also increased in human actinic keratoses, SCC and BCC as well as in murine SCC and BCC. The pattern of COX-2 expression was quite variable, occurring in a patchy distribution in some lesions with staining confined mainly to suprabasal cell layers. In general, COX-2 expression progressively became more extensive in benign papillomas and well-differentiated murine SCC. The staining was predominantly cytoplasmic and perinuclear in some focal areas in tissue stroma around both murine and human tumors. Western blot analysis confirmed negative COX-2 expression in normal skin, whereas acute UVB exposure resulted in increased enzyme expression, which continued to increase in developing papillomas and SCC. Because of the evidence indicating a pathogenic role for eicosanoids in murine and human skin neoplasms, we performed studies to assess the anti-inflammatory and anticarcinogenic effects of green tea extracts, which are potent antioxidants. Acute exposure of the human skin to UVB (minimum erythema dose x 4) caused a transient enhancement of the COX-2 expression, which reverted to baseline within hours; however, in murine skin the expression persisted for several days. Pretreatment with the topically applied green tea extract (1 mg/cm2) largely abrogated the acute COX-2 response to UVB in mice or humans. In summary, enhanced COX-2 expression serves as a marker of epidermal UVB exposure for murine and human NMSC. These results suggest that COX-2 inhibitors could have potent anticarcinogenic effects in UVB-induced skin cancer.

Calgranulins S100A8 and S100A9 are negatively regulated by glucocorticoids in a c-Fos-dependent manner and overexpressed throughout skin carcinogenesis

The two calgranulins S100A8 and S100A9 were found to be differentially expressed at sites of acute and chronic inflammation. Here we have employed the phorbol ester-induced multistage skin carcinogenesis protocol in mice to determine the expression of both genes in inflamed skin and in skin tumors. We show that expression is coordinately induced by the phorbol ester TPA in epithelial cells as well as infiltrating leukocytes. By comparing S100A8 and S100A9 mRNA levels in wild type and c-Fos deficient mice (c-fos(-/-)) we found that expression is negatively regulated by c-Fos/AP-1. Glucocorticoids, which exhibit potent anti-inflammatory and anti-tumor promoting activities repressed TPA-mediated S100A8 and S100A9 induction in wild type, but not in c-fos(-/-) mice, thus identifying both genes as the first examples of AP-1 target genes whose repression of TPA-induced transcription by glucocorticoids depends on c-Fos. Finally, we show that enhanced expression is not restricted to the initial TPA-induced inflammatory response but is observed at all stages of skin carcinogenesis. These data identify S100A8 and S100A9 as novel, tumor-associated genes and may point to an as yet unrecognized function of both genes in the development of epithelial skin tumors.

Calcium-dependent involucrin expression is inversely regulated by protein kinase C (PKC)alpha and PKCdelta

Calcium is an important physiologic regulator of keratinocyte function that may regulate keratinocyte differentiation via modulation of protein kinase C (PKC) activity. PKCalpha and PKCdelta are two PKC isoforms that are expressed at high levels in keratinocytes. In the present study, we examine the effect of PKCdelta and PKCalpha on calcium-dependent keratinocyte differentiation as measured by effects on involucrin (hINV) gene expression. Our studies indicate that calcium increases hINV promoter activity and endogenous hINV gene expression. This response requires PKCdelta, as evidenced by the observation that treatment with dominant-negative PKCdelta inhibits calcium-dependent hINV promoter activity, whereas wild type PKCdelta increases activity. PKCalpha, in contrast, inhibits calcium-dependent hINV promoter activation, a finding that is consistent with the ability of dominant-negative PKCalpha and the PKCalpha inhibitor, Go6976, to increase hINV gene expression. The calcium-dependent regulatory response is mediated by an AP1 transcription factor-binding site located within the hINV promoter distal regulatory region that is also required for PKCdelta-dependent regulation; moreover, both calcium and PKCdelta produce similar, but not identical, changes in AP1 factor expression. A key question is whether calcium directly influences PKC isoform function. Our studies show that calcium does not regulate PKCalpha or delta levels or cause a marked redistribution to membranes. However, tyrosine phosphorylation of PKCdelta is markedly increased following calcium treatment. These findings suggest that PKCalpha and PKCdelta are required for, and modulate, calcium-dependent keratinocyte differentiation in opposing directions.

Regulation of cyclooxygenase-2 expression by phospholipase D in human amnion-derived WISH cells

Prostaglandins (PGs) are known to play a key role in the initiation of labor, but the mechanisms regulating their synthesis in amnion are largely unknown. In this study, the regulatory mechanisms for PGE(2) production during phospholipase D (PLD) and p38-dependent activation of WISH cells were investigated. We found that the stimulation of WISH cells with interleukin (IL)-1 beta elicited dose-dependent synthesis of cyclooxygenase-2 (COX-2) mRNA, protein, and their products, PGE(2). Moreover, the treatment of [(3)H]myristate-labeled cells in the presence of 1-butanol caused the dose-dependent formation of [(3)H]phosphatidylbutanol (PBt), a product specific to PLD activity. Pretreating the cells with 1-butanol and Ro 31-8220 inhibited the IL-1 beta-induced COX-2 expression, but 3-butanol did not affect this response. In addition, evidence that PLD was involved in the stimulation of COX-2 expression was provided by the observations that COX-2 expression was stimulated by the dioctanoyl phosphatidic acid (PA) and that the prevention of PA dephosphorylation by 1-propranolol potentiated COX-2 expression by IL-1 beta. Moreover, IL-1 beta stimulation of the cells caused the phosphorylation of p38 and extracellular signal-regulated kinase (ERK), and IL-1 beta-induced COX-2 expression was inhibited by the pretreatment of WISH cells with a p38 inhibitor, in contrast ERK upstream inhibitor had no effect. Furthermore, Ro 31-8220 inhibited IL-1 beta-induced p38 phosphorylation but not ERK phosphorylation. The results of this study indicate that in human amnion cells, IL-1 beta might activate PLD through an upstream protein kinase C to elicit p38 and finally induce COX-2 expression.