AP-1 Binding Activity Research Articles

Sulforaphane controls TPA-induced MMP-9 expression through the NF-κB signaling pathway, but not AP-1, in MCF-7 breast cancer cells

Sulforaphane [1-isothiocyanato-4-(methylsulfinyl)-butane] is an isothiocyanate found in some cruciferous vegetables, especially broccoli. Sulforaphane has been shown to display anti-cancer properties against various cancer cell lines. Matrix metalloproteinase-9 (MMP-9), which degrades the extracellular matrix (ECM), plays an important role in cancer cell invasion. In this study, we investigated the effect of sulforaphane on 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced MMP-9 expression and cell invasion in MCF-7 cells. TPA-induced MMP-9 expression and cell invasion were decreased by sulforaphane treatment. TPA substantially increased NF-κB and AP-1 DNA binding activity. Pre-treatment with sulforaphane inhibited TPA-stimulated NF-κB binding activity, but not AP-1 binding activity. In addition, we found that sulforaphane suppressed NF-κB activation, by inhibiting phosphorylation of IκB in TPA-treated MCF-7 cells. In this study, we demonstrated that the inhibition of TPA-induced MMP-9 expression and cell invasion by sulforaphane was mediated by the suppression of the NF-κB pathway in MCF-7 cells. [BMB Reports 2013; 46(4): 201-206]

Resveratrol Induces Long-Lasting IL-8 Expression and Peculiar EGFR Activation/Distribution in Human Keratinocytes: Mechanisms and Implications for Skin Administration

Anti-inflammatory and skin tumour preventing effects of resveratrol have been extensively studied pre-clinically and resveratrol has been proposed for clinical investigations. To provide a basis or/and limitations for topical administration to human skin, molecular mechanisms underlying resveratrol effects towards normal human epidermal keratinocytes (NHEK) were evaluated. NHEK were challenged by either resveratrol alone or by its combination with TNFalpha or TGFalpha, and time-dependent molecular events were monitored. Interleukin 8 (IL-8) expression and its mRNA stability, ERK1/2, p65/RelA, and EGFR phosphorylation were determined. Intracellular distribution of EGFR/P-EGFR was measured in the membrane, cytoplasmic, and nuclear fractions. Specific DNA binding activity of NFκB (p65/RelA) and AP-1(c-Fos), NHEK proliferation, and molecular markers of apoptosis/cell cycle were detected. Resveratrol induced delayed, long-lasting and steadily growing IL-8 gene and protein over-expression as well as enhanced EGFR phosphorylation, both abrogated by the EGFR kinase inhibitor PD168393. However, resveratrol did not act as a phosphatase inhibitor. ERK phosphorylation was transiently inhibited at early time-points and activated at 6–24 h. Accordingly, c-Fos-specific DNA binding was increased by resveratrol. Cellular distribution of EGFR/P-EGFR was shifted to membrane and nucleus while cytosolic levels were reduced concomitant with enhanced degradation. Notwithstanding high nuclear levels of EGFR/P-EGFR, spontaneous and TGFalpha-triggered cell proliferation was strongly suppressed by resveratrol mainly through cell cycle arrest.Conclusions/SignificanceResveratrol synergized with TNFα in the induction of delayed, long-lasting IL-8 expression through sustained EGFR-ERK axis activation. The time course indicates that resveratrol metabolites could be implicated. Topical administration of Resv to psoriatic patients over-expressing TNFα, IL-8 and EGFR-ERK in the skin should be cautiously considered. Since high nuclear levels of EGFR correspond to increased risk of tumorigenesis, chronic resveratrol application to the skin may be potentially dangerous. Wound healing acceleration by resveratrol could not be envisaged due to its anti-proliferative effects towards normal keratinocytes.

Thalidomide inhibits fibronectin production in TGF-β1-treated normal and keloid fibroblasts via inhibition of the p38/Smad3 pathway

Keloids are characterized by the vigorously continuous production of extracellular matrix protein and aberrant cytokine activity in the dermis. There is a growing body of evidence that thalidomide, α-N-phthalimidoglutarimide, has anti-fibrotic properties. The aims were to examine possible therapeutic effects of thalidomide on fibronectin expression in transforming growth factor-β1 (TGF-β1)-treated normal fibroblasts (NFs) and keloid-derived fibroblasts (KFs) and the underlying mechanism of action, especially the involvement of mitogen-activated protein kinase (MAPKs) and Sma- and Mad-related family (Smads) pathways. In surgically removed human tissues, TGF-β1 and fibronectin immunoreactivity was high in keloid tissue, but barely detectable in normal tissue. TGF-β1 induced significant fibronectin expression in NFs and KFs and the effect was inhibited by pretreatment with thalidomide. TGF-β1 also induced phosphorylation of MAPKs (ERK1/2, p38, and JNK) and Smad2/3 and pretreatment with PD98059 (an ERK1/2 inhibitor), SB203580 (a p38 inhibitor), or SP600125 (a JNK inhibitor) inhibited TGF-β1-induced fibronectin expression. Furthermore, pretreatment with thalidomide inhibited the TGF-β1-induced phosphorylation of p38 and Smad3, but not that of ERK1/2, JNK, and Smad2. In addition, thalidomide pretreatment inhibited the TGF-β-induced DNA binding activity of AP-1 and Smad3/4, caused fibronectin degradation by increasing the activity of matrix metalloproteinase 9, and decreased production of TGF-β1 and fibronectin and the number of fibroblasts in an in vivo keloid model. These results show that thalidomide has an antifibrotic effect on keloid fibroblasts that is caused by suppression of TGF-β1-induced p38 and Smad3 signaling. Our findings indicate that thalidomide may be a potential candidate drug for the treatment and prevention of keloids.

Suppressive effects of an ethanol extract of Gleditsia sinensis thorns on human SNU-5 gastric cancer cells

The thorns of Gleditsia sinensis are a traditional Oriental medicine used for the treatment of swelling, suppuration, carbuncle and skin diseases. In the present study, we identified a novel molecular mechanism by which an ethanol extract of Gleditsia sinensis thorns (EEGS) inhibits the growth of the SNU-5 human gastric cancer cell line. EEGS treatment inhibited cell growth and was associated with G1 phase cell cycle arrest at a concentration of 400µg/ml (IC50) in SNU-5 cells. Treatment with EEGS also stimulated p21WAF1 expression, which significantly decreased the expression of cyclins and cyclin-dependent kinases (CDKs). Further study suggested that p38 MAP kinase pathways may be involved in the inhibition of cell proliferation through p21WAF1‑dependent G1 phase cell cycle arrest in EEGS-treated cells. In addition, NF-κB and AP-1 transcription factor binding sites were identified as the cis-elements for tumor necrosis factor-α (TNF-α)-induced matrix metalloproteinase-9 (MMP-9) expression in SNU-5 cells, as determined by gel-shift assay. Treatment of cells with EEGS suppressed MMP-9 expression induced by TNF-α via a decrease in the binding activity of both NF-κB and AP-1 motifs. These data demonstrate that EEGS-mediated inhibition of cell growth appears to involve the activation of p38 MAP kinase, subsequently leading to the induction of p21WAF1 and the downregulation of cyclinD1/CDK4 and cyclin E/CDK2 complexes. Moreover, EEGS strongly inhibited TNF-α-induced MMP-9 expression by impeding the DNA binding activity of NF-κB and AP-1. Overall, these results provide a potential mechanism for EEGS in the treatment of gastric cancer.

Interleukin-20 Promotes Migration of Bladder Cancer Cells through Extracellular Signal-regulated Kinase (ERK)-mediated MMP-9 Protein Expression Leading to Nuclear Factor (NF-κB) Activation by Inducing the Up-regulation of p21WAF1 Protein Expression *

The role of inflammatory cytokine interleukin-20 (IL-20) has not yet been studied in cancer biology. Here, we demonstrated up-regulation of both IL-20 and IL-20R1 in muscle-invasive bladder cancer patients. The expressions of IL-20 and IL-20R1 were observed in bladder cancer 5637 and T-24 cells. We found that IL-20 significantly increased the expression of matrix metalloproteinase (MMP)-9 via binding activity of NF-κB and AP-1 in bladder cancer cells and stimulated the activation of ERK1/2, JNK, p38 MAPK, and JAK-STAT signaling. Among the pathways examined, only ERK1/2 inhibitor U0126 significantly inhibited IL-20-induced migration and invasion. Moreover, siRNA knockdown of IL-20R1 suppressed migration, invasion, ERK1/2 activation, and NF-κB-mediated MMP-9 expression induced by IL-20. Unexpectedly, the cell cycle inhibitor p21(WAF1) was induced by IL-20 treatment without altering cell cycle progression. Blockade of p21(WAF1) function by siRNA reversed migration, invasion, activation of ERK signaling, MMP-9 expression, and activation of NF-κB in IL-20-treated cells. In addition, IL-20 induced the activation of IκB kinase, the degradation and phosphorylation of IκBα, and NF-κB p65 nuclear translocation, which was regulated by ERK1/2. IL-20 stimulated the recruitment of p65 to the MMP-9 promoter region. Finally, the IL-20-induced migration and invasion of cells was confirmed by IL-20 gene transfection and by addition of anti-IL-20 antibody. This is the first report that p21(WAF1) is involved in ERK1/2-mediated MMP-9 expression via increased binding activity of NF-κB, which resulted in the induction of migration in IL-20/IL-20R1 dyad-induced bladder cancer cells. These unexpected results might provide a critical new target for the treatment of bladder cancer.

Activation of EGFR/MEK/ERK/AP-1 signaling mediated by 1,2-naphthoquinone, an atmospheric electrophile, in human pulmonary A549 cells

1,2-Naphthoquinone (1,2-NQ) is found to be an electrophile contaminated in the atmosphere. Although we found that 1,2-NQ activates epidermal growth factor receptor (EGFR) coupled to inhibition of protein tyrosine phosphatase 1B (PTP1B) activity through covalent modification of Cys121 in human epithelial A431 cells, modulation of its downstream signal transduction pathway caused by 1,2-NQ remains to be elucidated. In the present study, we examined whether 1,2-NQ could affect such cellular signaling in human pulmonary A549 cells. Exposure of A549 cells to 1,2-NQ increased EGFR phosphorylation, resulting in activation of MEK/ERK signaling that was blocked by either PD15035 or PD98059. As a result, DNA binding activity of transcription factor AP-1 was enhanced during exposure to 1,2-NQ in the cells. These results suggest that the atmospheric electrophile phosphorylates EGFR, thereby activating the MEK/ERK/AP-1 signal transduction pathway in A549 cells.

IL-17A Induces Pro-Inflammatory Cytokines Production in Macrophages via MAPKinases, NF-κB and AP-1

Background: Interleukin (IL)-17A, a newly identified cytokine, may participate in the transition of a stable plaque into an unstable plaque. Macrophages play a critical role in the destabilization of atherosclerotic plaque. Methods: RAW 264.7 cells were stimulated with IL-17A. The mRNA expression of inflammatory cytokines was determined by RT-PCR. The cytokines production in the supernatants was measured by ELISA. Small interfering RNA (siRNA) was used to confirm that IL-17A-induced pro-inflammatory cytokines production via IL-17RA signaling. The western blot assay was used to detect the phosphorylation of MAPKinases including p38 and ERK1/2. The DNA binding activity of nuclear factor NF-κB and AP-1 were detected by EMSA. Results: IL-17A induced the production of pro-inflammatory cytokines in macrophages in a time- and dose-dependent manner, such as tumor necrosis factor (TNF)-a, IL-1ß, and IL-6. Meanwhile, IL-17A resulted in the phosphorylation of p38 and ERK1/2 and increased DNA-binding activity of NF-κB and AP-1. Pharmacological inhibitors of p38 and ERK1/2 partly attenuated IL-17A-induced TNF-a, IL-1ß, and IL-6 production. Either NF-κB inhibitor or AP-1 inhibitor also partly decreased the IL-17A-induced cytokine production. Conclusions: IL-17A induces pro-inflammatory cytokines production in macrophages via MAPKinases, NF-κB and AP-1 pathway.

Combined Effects of PPARγAgonists and Epidermal Growth Factor Receptor Inhibitors in Human Proximal Tubule Cells

We aimed to determine whether epidermal growth factor receptor (EGFR) inhibition, in addition to a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, prevents high-glucose-induced proximal tubular fibrosis, inflammation, and sodium and water retention in human proximal tubule cells exposed to normal glucose; high glucose; high glucose with the PPARγ agonist pioglitazone or with the P-EGFR inhibitor, gefitinib; or high glucose with both pioglitazone and gefitinib. We have shown that high glucose increases AP-1 and NFκB binding activity, downstream phosphorylation of EGFR and Erk1/2, and fibronectin and collagen IV expression. Pioglitazone reversed these effects but upregulated NHE3 and AQP1 expression. Gefitinib inhibited high glucose induced fibronectin and collagen IV, and EGFR and Erk1/2 phosphorylation and reversed pioglitazone-induced increases in NHE3 and AQP1 expression. Our data suggests that combination of an EGFR inhibitor and a PPARγ agonist mitigates high-glucose-induced fibrosis and inflammation and reverses the upregulation of transporters and channels involved in sodium and water retention in human proximal tubule cells. Hence EGFR blockade may hold promise, not only in limiting tubulointerstitial pathology in diabetic nephropathy, but also in limiting the sodium and water retention observed in patients with diabetes and exacerbated by PPARγ agonists.

Mycophenolic acid regulates spleen tyrosine kinase to repress tumour necrosis factor-alpha-induced monocyte chemotatic protein-1 production in cultured human aortic endothelial cells

Atherosclerosis develops from cascades of inflammatory processes. Spleen tyrosine kinase (Syk) and monocyte chemotatic protein-1 (MCP-1) play important roles in the pathogenesis of atherosclerosis. Mycophenolic acid (MPA) has an anti-inflammatory effect. We have investigated whether MPA regulates Syk to repress tumour necrosis factor-α (TNF-α)-induced MCP-1 production in cultured human aortic endothelial cells. Expression of MCP-1 mRNA and its protein were measured by real time RT-PCR and ELISA, respectively. Reactive oxygen species (ROS) production were measured using 2'7'-dichlorofluorescein diacetate. Activation of AP-1 and NF-κB were assessed by electrophoretic mobility shift assay. Tyrosine phosphorylation of Syk was examined by Western blot analysis. TNF-α increased MCP-1 at both mRNA and protein levels. TNF-α-induced MCP-1 mRNA expression was inhibited by N-acetylcysteine (NAC), Syk inhibitor, Syk-siRNA and MPA. TNF-α-induced MCP-1 protein production was also inhibited by Syk inhibitor and MPA. TNF-α increased DNA binding activity of AP-1 and NF-κB, whereas both AP-1 and NF-κB decoy oligodeoxynucleotides downregulated TNF-α-induced MCP-1 mRNA expression. TNF-α increased ROS generation, which was inhibited by NAC and MPA, but not by Syk inhibitor. TNF-α increased tyrosine phosphorylation of Syk, which was attenuated by NAC and MPA. MPA and Syk inhibitor attenuated TNF-α-induced DNA binding activity of NF-κB and AP-1. TNF-α induced MCP-1 expression via activation of AP-1 and NF-κB. AP-1 and NF-κB were mediated through ROS, followed by Syk. MPA exerts anti-inflammatory effect by inhibiting MCP-1 expression via suppression of ROS and Syk.

2′-Benzoyloxycinnamaldehyde inhibits nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 cells via regulation of AP-1 pathway

Cinnamaldehyde, an active compound of cinnamon, has been reported to exert various biological functions such as anti-inflammatory and anti-tumor activities. Previously, we showed that 2′-hydroxycinnamaldehyde (HCA) has an inhibitory effect on nitric oxide (NO) production through the inhibition of NF-κB signaling. In an effort to find a more effective anti-atherosclerotic agent, here we evaluated the anti-inflammatory effect of 2′-benzoyloxycinnamaldehyde (BCA) in RAW 264.7 murine macrophage cells. We showed that BCA more effectively inhibited NO production than HCA with less cytotoxicity. We also demonstrated that BCA inhibited the lipopolysaccharide (LPS)-induced expression of iNOS in a concentration-dependent manner. Signal transduction studies showed that BCA significantly inhibited the phosphorylation of SAPK/JNK and AP-1-dependent reporter gene activity. LPS-induced expression levels of JunB, c-Jun and c-Fos were also decreased by BCA treatment. Moreover, the LPS-induced DNA binding activity of AP-1 was markedly inhibited by BCA. The direct injection of BCA into mice inhibited the LPS-induced increase in plasma nitrite levels, confirming the anti-inflammatory effect of BCA in vivo. Overall, these observations suggest that BCA has the potential for use as an anti-atherosclerotic agent.

Differential activation of the inflammasome in THP-1 cells exposed to chrysotile asbestos and Libby “six-mix” amphiboles and subsequent activation of BEAS-2B cells

Inflammatory responses of THP-1 cells (macrophage cell line) exposed to chrysotile asbestos (Chry) and Libby six-mix (LIB) and the subsequent impact on bronchial epithelial cells were determined. Direct treatment of THP-1 cells with Chry caused cell death, activation of caspase-1 and release of IL-1β, while the addition of caspase-1 inhibitor, Z-YVAD-FMK, reduced IL-1β, suggesting that Chry activated the caspase-1 mediated Nod-like receptor protein 3 (NLRP3) inflammasome; by comparison, LIB had less effects on all of these parameters. Expression of antioxidant enzymes, protein oxidation and nitration, and lipid peroxides in THP-1 cells treated with the two particles suggest that LIB generated more reactive oxygen species (ROS) than the same dose of Chry. Differences in fiber length and surface area suggest a possible role for particulate size in the differential activation of the inflammasome. BEAS-2B cells, representing the bronchial epithelium, treated with supernatants of medium from Chry- or LIB-treated THP-1 cells (conditioned medium) activated the MAPK cascade, increased phosphorylation of ERK and Cot (MAP3K8), increased AP-1 binding activity and induced IL-6 release. To verify that IL-1β from THP-1 cells was responsible for activation of BEAS-2B, conditioned medium with added IL-1Ra, an IL-1β antagonist, was applied to BEAS-2B. Results show that IL-1Ra attenuated effects of conditioned medium, supporting a role of IL-1β, as a secondary mediator, in the transduction of inflammatory signaling from the macrophage to epithelial cells. The effects of LIB-conditioned medium appeared to be less dependent on IL-1β. In conclusion, Chry and LIB induce differential inflammatory responses in THP-1 cells that subsequently lead to differential effects in epithelial cells.

Rapamycin-induced modulation of HIV gene transcription attenuates progression of HIVAN

HIV-associated nephropathy (HIVAN) is the manifestation of HIV gene expression by kidney cells in the presence of specific host factors. Recently, rapamycin (sirolimus) has been demonstrated to modulate the progression of HIVAN. We hypothesized that rapamycin would modulate the progression of HIVAN by attenuating HIV gene expression. To test our hypothesis, three weeks old Tg26 mice (n=6) were administered either vehicle or rapamycin (5mg/kg, every other day, intraperitoneal) for eight weeks. At the end of the experimental period, the kidneys were harvested. In in vitro studies, human podocytes were transduced with either HIV-1 (NL4-3) or empty vector (EV), followed by treatment with either vehicle or rapamycin. Total RNA and proteins were extracted from renal tissues/cellular lysates and HIV gene transcription/translation was measured by real time PCR and Western blotting studies. Renal histological slides were graded for glomerular sclerosis and tubular dilatation with microcyst formation. Rapamycin attenuated both glomerular and tubular lesions in Tg26 mice. Rapamycin decreased transcription of HIV genes both in renal tissues as well as in HIV-1 transduced podocytes. Our data strongly indicate that HIV-1 long terminal repeat-mediated transcriptional activity was targeted by rapamycin. Rapamycin enhanced podocyte NF-κB and CREB activities but then it decreased AP-1 binding activity. Since expression of HIV genes by kidney cells has been demonstrated to be the key factor in the development HIVAN, it appears that rapamycin-induced altered transcription of HIV genes might have partly contributed to its disease modulating effects.

Diallyl trisulfide induces apoptosis in human breast cancer cells through ROS-mediated activation of JNK and AP-1

Multiple lines of evidence support an inverse association between consumption of garlic and the risk of cancer. Chemopreventive effects of garlic have been attributed to its oil-soluble sulfur ingredients, such as diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS), but their underlying molecular mechanisms remain largely unresolved. In the present study, we found that DATS showed the most potent anti-proliferative effects in human breast cancer MCF-7 cells. MCF-7 cells treated with DATS underwent apoptotic death as revealed by a progressive increase in the proportion of the sub-G0/G1 cell population and a typical pattern of annexin V/propidium iodide staining. DATS induced phosphorylation of the antiapoptotic Bcl-2 and proteolytic cleavage of poly(ADP-ribose)polymerase (PARP) in MCF-7 cells. DATS treatment activated c-Jun N-terminal kinase (JNK). DATS-induced apoptosis was blunted in MCF-7 cells treated with a specific JNK inhibitor SP600125 or transiently transfected with dominant negative JNK. DATS treatment resulted in accumulation of reactive oxygen species (ROS). DATS-induced apoptosis as well as activation of JNK was abrogated by N-acetyl-l-cysteine (NAC). Furthermore, DATS induced phosphorylation and expression of c-Jun, which were attenuated by NAC. MCF-7 cells treated with DATS also exhibited increased DNA binding activity of AP-1, which was blocked by NAC and the JNK inhibitor. Proteolytic cleavage of PARP induced by DATS was abrogated in the cells transfected with c-jun siRNA. Oral administration of 5μmol/kg DATS to female Balb/c mice inhibited the growth of human MCF-7 cell tumor xenografts. These results suggest that DATS-induced apoptosis is mediated through ROS generation and subsequent activation of JNK and AP-1.

Insulin-like growth factor-I regulates the neonatal immune response in infection and maturation by suppression of IFN-γ

Disturbances in Insulin-like growth factor-I (IGF-I) and dysregulation in neonatal immune responses have been associated with typical neonatal diseases. Immunosuppression by IGF-I might be a key regulator of neonatal immune responses in infection and maturation. However, information on IGF-I serum levels, IGF-I-receptor (IGF-IR) and effects on functional properties of neonatal immune cells is scarce. Neonatal cord blood samples were stimulated with anti-CD3/anti-CD28, PMA/ionomycin or LPS in a whole-blood assay, while IGF-I serum levels and IGF-I receptor expression were assessed. Furthermore the effect of IGF-I on cytokine expression, apoptosis and the DNA binding activity of AP-1 and NFκB was evaluated. IGF-I serum levels were within normal range. The IGF-I-receptor was present on the surface of cord blood CD3+CD4+lymphocytes and cord blood CD14+monocytes. Upon stimulation the IGF-I-R expression on lymphocytes was significantly upregulated. The addition of IGF-I (100ng/ml) to whole blood cultures inhibited the secretion of IFN-γ from PMA/ionomycin-stimulated cord blood mononuclear cells (CBMC). While IGF-I did not influence apoptosis in our experimental setting, it led to a distinct decrease in anti-CD3/CD28-stimulated DNA binding activity of AP-1 and NFκB. Thus IGF-I may be a key regulator of neonatal immune responses in maturation processes and inflammation by suppressing proinflammatory Th1 responses. Future in vivo studies need to elucidate whether disturbances of the IGF-I serum level and IGF-IR expression are associated with susceptibility for infections and subsequent diseases in neonates.

Emerging nonanticoagulant role of low molecular weight heparins on extravillous trophoblast functions and on heparin binding–epidermal growth factor and cystein-rich angiogenic inducer 61 expression

To examine the effects of low molecular weight heparins (LMWHs) on extravillous trophoblast (EVTC) invasiveness and on EVTC expression/secretion of heparin binding-EGF (HB-EGF) and cystein-rich angiogenic inducer 61 (Cyr61), both of which are involved in the process of EVTC invasion. Furthermore, to investigate the intracellular DNA binding activity of activator protein (AP)-1. Experimental study. Department of Obstetrics Gynecology, Università Cattolica del Sacro Cuore, Rome, Italy. Cultures of primary EVTC cells isolated from patients with first trimester unexplained recurrent miscarriage. The effects of LMWHs on EVTC invasiveness were examined by an in vitro matrigel invasion assay. Matrix metalloprotease-2 activity (MMP-2) was examined by gelatin zimography. HB-EGF and Cyr61 expression and secretion were studied by Western blot analysis and ELISA assay. AP-1 activity was measured through a multiwell colorimetric assay. The EVTC invasiveness, the expression/secretion of HB-EGF and Cyr61 proteins, and the AP-1 DNA binding activity in the presence of increasing concentrations of LMWHs were investigated. Both LMWHs, and primarily tinzaparin, increased EVTC invasiveness, by enhancing the MMP-2 proteolytic activity, and induced the expression/secretion of HB-EGF and Cyr61 in EVTC. This effect was mediated by an increased DNA binding activity of AP-1. Both LMWHs are able to promote EVTC development because they are able to stimulate the EVTC invasive properties. Our results may provide a possible biological rationale for the clinical use of LMWH for placental-mediated pregnancy complications unrelated to prothrombotic disorders.

Role of the p38 MAPK signaling pathway in mediating interleukin-28A-induced migration of UMUC-3 cells

Although interleukin-28A (IL-28A) is believed to have an antiviral effect, its role in tumor migration requires further examination. The present study was intended to verify the effect of IL-28A on the migration of UMUC-3 bladder cancer cells. IL-28A and its receptor IL-28AR1 mRNA were detected in UMUC-3 cells. Although exogenous IL-28A showed no effect on cell proliferation, a wound-healing migration assay showed that the migration of UMUC-3 cells was induced by IL-28A. Furthermore, treatment of the cells with IL-28A significantly promoted MMP-9 expression via binding activities of NF-κB and AP-1. IL-28A also induced the activation of p38 MAPK and Jak2-Stat2 signaling. Using the p38 MAPK inhibitor SB203580 and the dominant-negative plasmid DN-p38, we found evidence that the inhibition of p38 MAPK signaling suppressed the effects of IL-28A including wound-healing migration and MMP-9 expression by activation of NF-κB and AP-1 binding in UMUC-3 cells. However, Jak-2 inhibition by AG490 did not affect IL-28A-induced migration of UMUC-3 cells. Collectively, we suggest for the first time that the p38 MAPK pathway mediates IL-28A-induced cell migration through MMP-9 expression by activating NF-κB and AP-1 binding motifs.

MEKK1-MKK4-JNK-AP1 Pathway Negatively Regulates Rgs4 Expression in Colonic Smooth Muscle Cells

Background Regulator of G-protein Signaling 4 (RGS4) plays an important role in regulating smooth muscle contraction, cardiac development, neural plasticity and psychiatric disorder. However, the underlying regulatory mechanisms remain elusive. Our recent studies have shown that upregulation of Rgs4 by interleukin (IL)-1β is mediated by the activation of NFκB signaling and modulated by extracellular signal-regulated kinases, p38 mitogen-activated protein kinase, and phosphoinositide-3 kinase. Here we investigate the effect of the c-Jun N-terminal kinase (JNK) pathway on Rgs4 expression in rabbit colonic smooth muscle cells.Methodology/Principal FindingsCultured cells at first passage were treated with or without IL-1β (10 ng/ml) in the presence or absence of the selective JNK inhibitor (SP600125) or JNK small hairpin RNA (shRNA). The expression levels of Rgs4 mRNA and protein were determined by real-time RT-PCR and Western blot respectively. SP600125 or JNK shRNA increased Rgs4 expression in the absence or presence of IL-1β stimulation. Overexpression of MEKK1, the key upstream kinase of JNK, inhibited Rgs4 expression, which was reversed by co-expression of JNK shRNA or dominant-negative mutants for MKK4 or JNK. Both constitutive and inducible upregulation of Rgs4 expression by SP600125 was significantly inhibited by pretreatment with the transcription inhibitor, actinomycin D. Dual reporter assay showed that pretreatment with SP600125 sensitized the promoter activity of Rgs4 in response to IL-1β. Mutation of the AP1-binding site within Rgs4 promoter increased the promoter activity. Western blot analysis confirmed that IL-1β treatment increased the phosphorylation of JNK, ATF-2 and c-Jun. Gel shift and chromatin immunoprecipitation assays validated that IL-1β increased the in vitro and ex vivo binding activities of AP1 within rabbit Rgs4 promoter.Conclusion/SignificanceActivation of MEKK1-MKK4-JNK-AP1 signal pathway plays a tonic inhibitory role in regulating Rgs4 transcription in rabbit colonic smooth muscle cells. This negative regulation may aid in maintaining the transient level of RGS4 expression.

Chitooligosaccharide elicits acute inflammatory cytokine response through AP-1 pathway in human intestinal epithelial-like (Caco-2) cells

Chitooligosaccharides (COSs) are bioactive carbohydrate derivatives that have numerous health benefits, including stimulation of the immune system. The objectives of this study were to evaluate the effect of chitooligosaccharide (COS) on expression of a specific panel of cytokine genes involved in inflammation and to delineate the signal transduction pathway underlying the COS mediated inflammatory response. Human intestinal epithelial-like (Caco-2) cells were treated with COS (5000–10,000Da) and expression of a panel of eighty-four cytokine genes was analyzed by quantitative real-time PCR. COS induced up-regulation of a total of 11 genes including CCL20 and IL8 and concurrent down-regulation of 10 genes including pro-inflammatory mediators CCL15, CCL25 and IL1B. To further establish the signal transduction pathway of COS mediated response in Caco-2 cells, two major inflammatory signal transduction pathways (NF-κB and AP-1) were investigated. COS had inhibitory effect (P<0.01) on TNF-α induced NF-κB binding activity while stimulatory effect (P<0.001) on AP-1 binding activity. COS also inhibited the expression of RELA (P<0.01) and IKBKB (P<0.01) genes of NF-κB pathway while stimulate the expression of JUN (P<0.05) gene of AP-1 pathway. In conclusion, COS elicits an acute inflammatory cytokine response in Caco-2 cells and hence it has the potential to stimulate the immune system in the gut epithelium.

Abstract 2296: Aldose reductase inhibition prevents human colon cancer cells growth by miR-21 and FOXO3a-mediated regulation of PTEN

Abstract We have shown earlier that the inhibition of aldose reductase (AR), a NADPH-dependent aldo-keto reductase, prevents growth factor-induced proliferation of colon cancer cells in vitro and in vivo. Recent studies indicate that changes in microRNA (miRNA) expression can contribute to cancer by modulating the functional expression of critical genes involved in cancer growth and metastasis. However, the molecular mechanism(s) by which AR regulates miRNA expression and their dependent mitogenic effects in cancer cells is not known. Therefore, we investigated how AR regulates growth factor -induced expression of miRNAs in colon cancer cells. Our results indicate that inhibition of AR significantly down-regulated growth factor-induced miR-21 expression in HT29, SW480 and Caco-2 human colon cancer cells. Further, AR inhibition also increased PTEN, a direct target of miR-21 that contributes cancer cell growth and invasion. Inhibition of AR also prevented the EGF-induced phosphorylation of PTEN and FOXO3a, which prevents cell proliferation. Treatment of human colon cancer cells with AR inhibitor, fidarestat, prevented the EGF-induced DNA binding activity of AP1, phosphorylation of PI3K, AKT, c-Jun and c-Fos. More importantly, in HT29 human colon adenocarcinoma xenograft tissues, miR-21 expression was lower, and PTEN and FOXO3a levels were significantly higher in AR inhibitor-treated mice compared to controls. Collectively, these results show a novel role of AR in mediation of growth factor-induced colon cancer cell proliferation by increasing miR-21 expression and inactivating or decreasing PTEN and FOXO3a through the ROS/PI3K/AKT/AP1 pathway, indicating that AR inhibitors could be used for the prevention/therapy of colon carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2296. doi:1538-7445.AM2012-2296

18α-Glycyrrhetinic Acid Down-Regulates Expression of Type I and III Collagen via TGF-Β1/Smad Signaling Pathway in Human and Rat Hepatic Stellate Cells

Objective: To investigate the effects of 18α-glycyrrhetinic acid (18α-GA) on the expression of type I and III collagen in human and rat hepatic stellate cells (HSC) and to explore the role of TGF-β1/Smad signaling pathway involved.Methods: Following 18α-GA treatment, the cell viability and cell growth were detected to determine the optimal concentration of 18α-GA. The expressions of TGF-β1/Smad signaling-related genes including type I and III collagen in human and rat HSCs before and after 18α-GA treatment were measured by real time PCR. The expression of related proteins was verified by western blot assay. The phosphorylation level of Smad2 and Smad3 was detected by immunocytochemistry. The DNA binding activities of SP-1, AP-1 and NF-κB were measured by both EMSA and ArrayStar transcription factor activity assay.Results: 18α-GA could decrease the mRNA and protein expression of Smad3, type I and III collagen, increase the Smad7 expression in human and rat HSCs (P<0.05), and reduce phosphorylation level of Smad3 at 24 h and 48 h after treatment. The DNA binding activities of transcription factors were suppressed by 18α-GA in human and rat HSCs at 24 h, and the activities reduced in a time dependent manner with the lowest activities at 48 h, especially for SP-1.Conclusion: 18α-GA could inhibit the mRNA and protein expression of type I and III collagen in human and rat HSCs, which may be attributed to down-regulation of Smad3, up-regulation of Smad7, and inhibition of DNA binding activities of SP-1, AP-1 and NF-κB.