Estrogen‐related receptor alpha triggers the proliferation and migration of human non‐small cell lung cancer via interleukin‐6

Human non‐small cell lung cancer (NSCLC) is one of the leading causes of cancer deaths worldwide. Estrogenic signals have been suggested to be important for the growth and metastasis of NSCLC cells. Our present data showed that estrogen‐related receptor alpha (ERRα), while not ERRβ or ERRγ, was significantly elevated in NSCLC cell lines as compared with that in normal bronchial epithelial cell line BEAS‐2B. The expression of ERRα in clinical NSCLC tissues was significantly greater than that in their matched normal adjacent tissues. Over expression of ERRα can trigger the proliferation, migration, and invasion of NSCLC cells, while si‐ERRα or ERRα inhibitor showed opposite effects. ERRα can increase the mRNA and protein expression of IL‐6, while not IL‐8, IL‐10, IL‐22, VEGF, TGF‐β, or TNF‐α, in NSCLC cells. Silence of IL‐6 attenuated ERRα induced proliferation and cell invasion. Furthermore, our data revealed the inhibition of NF‐κB, while not ERK1/2 or PI3K/Akt, abolished ERRα induced production of IL‐6. This might be due to that overexpression of ERRα can increase the expression and nuclear translocation of p65 in NSCLC cells. Collectively, our data showed that activation of NF‐κB/IL‐6 is involved in ERRα induced migration and invasion of NSCLC cells. It suggested that ERRα might be a potential target for NSCLC treatment.     

2,3,7,8‐Tetrachlorodibenzo‐p‐dioxin promotes astrocyte activation and the secretion of tumor necrosis factor‐α via PKC/SSeCKS‐dependent mechanisms

2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) is a ubiquitous environmental pollutant that could induce significant toxic effects in the human nervous system. However, the underlying molecular mechanism has not been entirely elucidated. Reactive astrogliosis has implicated in various neurological diseases via the production of a variety of pro‐inflammatory mediators. Herein, we investigated the potential role of TCDD in facilitating astrocyte activation and the underlying molecular mechanisms. We showed that TCDD induced rapid astrocyte activation following TCDD exposure, which was accompanied by significantly elevated expression of Src‐Suppressed‐C Kinase Substrate (SSeCKS), a protein involved in protein kinase C (PKC)‐mediated Nuclear Factor kappa B signaling, suggesting a possible involvement of PKC‐induced SSeCKS activation in TCDD‐triggered reactive astroglia. In keeping with the finding, we found that the level of phosphorylated Nuclear Factor kappa B p65 was remarkably increased after TCDD treatment. Furthermore, interference of SSeCKS attenuated TCDD‐induced inducible nitric oxide synthase, glial fibrillary acidic protein, phospho‐p65 expression, and tumor necrosis factor‐α secretion in astrocytes. In addition, pre‐treatment with PKC inhibitor also attenuated TCDD‐induced astrocyte activation, as well as SSeCKS expression. Interestingly, we found that TCDD treatment could lead to SSeCKS perinuclear localization, which could be abolished after treatment with PKC inhibitor. Finally, we showed that inhibition of PKC activity or SSeCKS expression would impair TCDD‐triggered tumor necrosis factor‐α secretion. Our results suggested that TCDD exposure could lead to astrocyte activation through PKC/SSeCKS‐dependent mechanisms, highlighting that astrocytes might be important target of TCDD‐induced neurotoxicity.

     

Curcumin has immunomodulatory effects on RANKL‐stimulated osteoclastogenesis in vitro and titanium nanoparticle‐induced bone loss in vivo

Wear particle‐stimulated inflammatory bone destruction and the consequent aseptic loosening remain the primary causes of artificial prosthesis failure and revision. Previous studies have demonstrated that curcumin has a protective effect on bone disorders and inflammatory diseases and can ameliorate polymethylmethacrylate‐induced osteolysis in vivo. However, the effect on immunomodulation and the definitive mechanism by which curcumin reduces the receptor activators of nuclear factor‐kappa B ligand (RANKL)‐stimulated osteoclast formation and prevents the activation of osteoclastic signalling pathways are unclear. In this work, the immunomodulation effect and anti‐osteoclastogenesis capacities exerted by curcumin on titanium nanoparticle‐stimulated macrophage polarization and on RANKL‐mediated osteoclast activation and differentiation in osteoclastic precursor cells in vitro were investigated. As expected, curcumin inhibited RANKL‐stimulated osteoclast maturation and formation and had an immunomodulatory effect on macrophage polarization in vitro. Furthermore, studies aimed to identify the potential molecular and cellular mechanisms revealed that this protective effect of curcumin on osteoclastogenesis occurred through the amelioration of the activation of Akt/NF‐κB/NFATc1 pathways. Additionally, an in vivo mouse calvarial bone destruction model further confirmed that curcumin ameliorated the severity of titanium nanoparticle‐stimulated bone loss and destruction. Our results conclusively indicated that curcumin, a major biologic component of Curcuma longa with anti‐inflammatory and immunomodulatory properties, may serve as a potential therapeutic agent for osteoclastic diseases.     

The Importance of Toll‐like Receptors in NF‐κB Signaling Pathway Activation by Helicobacter pylori Infection and the Regulators of this Response

Helicobacter pylori (H. pylori) is a common pathogenic bacterium in the stomach that infects almost half of the population worldwide and is closely related to gastric diseases and some extragastric diseases, including iron‐deficiency anemia and idiopathic thrombocytopenic purpura. Both the Maastricht IV/Florence consensus report and the Kyoto global consensus report have proposed the eradication of H. pylori to prevent gastric cancer as H.pylori has been shown to be a major cause of gastric carcinogenesis. The interactions between H. pylori and host receptors induce the release of the proinflammatory cytokines by activating proinflammatory signaling pathways such as nuclear factor kappa B (NF‐κB), which plays a central role in inflammation, immune response, and carcinogenesis. Among these receptors, Toll‐like receptors (TLRs) are classical pattern recognition receptors in the recognition of H. pylori and the mediation of the host inflammatory and immune responses to H. pylori. TLR polymorphisms also contribute to the clinical consequences of H. pylori infection. In this review, we focus on the functions of TLRs in the NF‐κB signaling pathway activated by H. pylori, the regulators modulating this response, and the functions of TLR polymorphisms in H.pylori‐related diseases.     

Propofol inhibits proliferation and induces neuroapoptosis of hippocampal neurons in vitro via downregulation of NF‐κB p65 and Bcl‐2 and upregulation of caspase‐3

Propofol is widely used in paediatric anaesthesia and intensive care unit because of its essentially short‐acting anaesthetic effect. Recent data have shown that propofol induced neurotoxicity in developing brain. However, the mechanisms are not extremely clear. To gain a better insight into the toxic effects of propofol on hippocampal neurons, we treated cells at the days in vitro 7 (DIV 7), which were prepared from Sprague–Dawley embryos at the 18th day of gestation, with propofol (0.1–1000 μM) for 3 h. A significant decrease in neuronal proliferation and a remarkable increase in neuroapoptosis were observed in DIV 7 hippocampal neurons as measured by 3‐(4,5‐dimethylthiazole‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay and apoptosis assay respectively. Moreover, propofol treatment decreased the nuclear factor kappaB (NF‐κB) p65 expression, which was accompanied by a reduction in B‐cell lymphoma 2 (Bcl‐2) mRNA and protein levels, increased caspase‐3 mRNA and activation of caspase‐3 protein. These results indicated that downregulation of NF‐κB p65 and Bcl‐2 were involved in the potential mechanisms of propofol‐induced neurotoxicity. This likely led to the caspase‐3 activation, triggered apoptosis and inhibited the neuronal growth and proliferation that we have observed in our in vitro systems. Copyright © 2014 John Wiley & Sons, Ltd.     

A lucid review of Helicobacter pylori‐induced DNA damage in gastric cancer

Helicobacter pylori (H pylori) is the main risk factor for gastric cancer (GC). In recent years, many studies have addressed the effects of H pylori itself and of H pylori‐induced chronic inflammation on DNA damage. Unrepaired or inappropriately repaired DNA damage is one possible carcinogenic mechanism. We may conclude that H pylori‐induced DNA damage is one of the carcinogenic mechanisms of GC. In this review, we summarize the interactions between H pylori and DNA damage and the effects of H pylori‐induced DNA damage on GC. Then, focusing on oxidative stress, we introduce the application of antioxidants in GC. At the end of this review, we discuss the outlook for further research on H pylori‐induced DNA damage.     

Integrin‐linked kinase is involved in TNF‐α‐induced inducible nitric‐oxide synthase expression in myoblasts

Tumor necrosis factor‐α (TNF‐α) is a pleiotropic cytokine produced by activated macrophages. Nitric oxide (NO) is a highly reactive nitrogen radical implicated in inflammatory responses. We investigated the signaling pathway involved in inducible nitric oxide synthase (iNOS) expression and NO production stimulated by TNF‐α in cultured myoblasts. TNF‐α stimulation caused iNOS expression and NO production in myoblasts (G7 cells). TNF‐α‐mediated iNOS expression was attenuated by integrin‐linked kinase (ILK) inhibitor (KP392) and siRNA. Pretreatment with Akt inhibitor, mammalian target of rapamycin (mTOR) inhibitor (rapamycin), NF‐κB inhibitor (PDTC), and IκB protease inhibitor (TPCK) also inhibited the potentiating action of TNF‐α. Stimulation of cells with TNF‐α increased ILK kinase activity. TNF‐α also increased the Akt and mTOR phosphorylation. TNF‐α mediated an increase of NF‐κB‐specific DNA–protein complex formation, p65 translocation into nucleus, NF‐κB‐luciferase activity was inhibited by KP392, Akt inhibitor, and rapamycin. Our results suggest that TNF‐α increased iNOS expression and NO production in myoblasts via the ILK/Akt/mTOR and NF‐κB signaling pathway. J. Cell. Biochem. 109: 1244–1253, 2010. © 2010 Wiley‐Liss, Inc.     

p97/VCP promotes Cullin‐RING‐ubiquitin‐ligase/proteasome‐dependent degradation of IκBα and the preceding liberation of RelA from ubiquitinated IκBα

Cullin‐RING‐ubiquitin‐ligase (CRL)‐dependent ubiquitination of the nuclear factor kappa B (NF‐κB) inhibitor IκBα and its subsequent degradation by the proteasome usually precede NF‐κB/RelA nuclear activity. Through removal of the CRL‐activating modification of their cullin subunit with the ubiquitin (Ub)‐like modifier NEDD8, the COP9 signalosome (CSN) opposes CRL Ub‐ligase activity. While RelA phosphorylation was observed to mediate NF‐κB activation independent of Ub‐proteasome‐pathway (UPP)‐dependent turnover of IκBα in some studies, a strict requirement of the p97/VCP ATPase for both, IκBα degradation and NF‐κB activation, was reported in others. In this study, we thus aimed to reconcile the mechanism for tumour necrosis factor (TNF)‐induced NF‐κB activation. We found that inducible phosphorylation of RelA is accomplished in an IKK‐complex‐dependent manner within the NF‐κB/RelA‐IκBα‐complex contemporaneous with the phosphorylation of IκBα, and that RelA phosphorylation is not sufficient to dissociate NF‐κB/RelA from IκBα. Subsequent to CRL‐dependent IκBα ubiquitination functional p97/VCP is essentially required for efficient liberation of (phosphorylated) RelA from IκBα, preceding p97/VCP‐promoted timely and efficient degradation of IκBα as well as simultaneous NF‐κB/RelA nuclear translocation. Collectively, our data add new facets to the knowledge about maintenance of IκBα and RelA expression, likely depending on p97/VCP‐supported scheduled basal NF‐κB activity, and the mechanism of TNF‐induced NF‐κB activation.     

Alpha B‐crystallin promotes the invasion and metastasis of gastric cancer via NF‐κB‐induced epithelial‐mesenchymal transition

Alpha B‐crystallin (CRYAB) is overexpressed in a variety of cancers. However, little is known about its specific function and regulatory mechanism in gastric cancer. Here, we first explore the role of CRYAB in gastric cancer progression and metastasis. The expression of CRYAB was determined by western blot and immunohistochemistry in gastric cancer tissues. Besides, methods including stably transfected against CRYAB into gastric cancer cells, western blot, migration and invasion assays in vitro and metastasis assay in vivo were also conducted. The expression of CRYAB is up‐regulated in gastric cancer tissues compared with matched normal tissues. High expression level of CRYAB is closely correlated with cancer metastasis and shorter survival time in patients with gastric cancer. Additionally, CRYAB silencing significantly suppresses epithelial‐mesenchymal transition (EMT), migration and invasion of gastric cancer cells in vitro and in vivo, whereas CRYAB overexpression dramatically reverses these events. Mechanically, CRYAB facilitates gastric cancer cells invasion and metastasis via nuclear factor‐κ‐gene binding (NF‐κB)‐regulated EMT. These findings suggest that CRYAB expression predicts a poor prognosis in patients with gastric cancer. Besides, CRYAB contributes to gastric cancer cells migration and invasion via EMT, mediated by the NF‐κB signalling pathway, thus possibly providing a novel therapeutic target for gastric cancer.     

The protective effect of sinapic acid in osteoarthritis: In vitro and in vivo studies

The anti‐inflammatory effect of sinapic acid (SA) has been reported in several studies. However, whether SA has the same effect on osteoarthritis (OA) has yet to be clearly elucidated. We designed a series of in vitro and in vivo procedures to verify the above conjecture. Compared with controls, SA‐pretreated human chondrocytes showed lower levels of interleukin (IL)‐1β‐induced IL‐6, prostaglandin E2 (PGE2), nitric oxide (NO) and tumour necrosis factor‐α (TNF‐α) in vitro. Meanwhile, SA could also reverse the degradation of type II collage and aggrecan, as well as the overproduction of matrix metalloproteinase‐9 (MMP‐9) and matrix metalloproteinase‐13 (MMP‐13), inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)‐2 and a disintegrin and metalloproteinase thrombospondin motifs (ADAMTS)‐5. Furthermore, activation of nuclear factor κB (NF‐κB), which was induced by IL‐1β, was also inhibited by SA through the pathway of nuclear factor‐erythroid 2‐related factor‐2 (Nrf2)/heme oxygenase 1. In vivo, SA could delay the progress of mice OA models. We propose that SA may be applied as a potential therapeutic drug in OA treatment.     

Chemopreventive efficacy of green tea drinking against 1,2‐dimethyl hydrazine‐induced rat colon carcinogenesis

Colorectal cancer is one of the leading causes of tumour‐related deaths. In the present study, the chemopreventive effect of green tea on 1,2‐dimethylhydrazine (DMH)‐induced colon carcinogenesis was studied in male Wistar rats. The DMH group received subcutaneous injections of DMH (30 mg kg^?1 body weight) once a week for 30 weeks, the normal group received the vehicle of DMH, and the DMH + green tea group received DMH simultaneously with 1% green tea as their sole source of drinking fluid throughout the experimental period. In the DMH group treated with green tea, significant reductions in gene overexpressions of colonic nuclear factor κB (NF‐κB), tumour necrosis factor α, inducible nitric oxide synthase and cyclooxygenase 2, and NF‐κB immunostaining indicates the anti‐inflammatory effect of green tea in attenuating colon cancer. Moreover, the anti‐angiogenic and anti‐invasiveness effects of green tea were revealed as reductions of both vascular endothelial growth factor and matrix metalloproteinase‐7 mRNA expression levels. These effects were confirmed by the significant reduction of serum tumour necrosis factor α, C‐reactive protein levels, inhibition of tumour incidence, and nearly normal survival rate and colonic architecture. It can be concluded that green tea exerts a potent chemopreventive effect on colon carcinogenesis possibly due to the inhibition of NF‐κB. Copyright © 2012 John Wiley & Sons, Ltd.     

PMC,a potent hydrophilic α‐tocopherol derivative,inhibits NF‐κB activation via PP2A but not IκBα‐dependent signals in vascular smooth muscle cells

The hydrophilic α‐tocopherol derivative, 2,2,5,7,8‐pentamethyl‐6‐hydroxychromane (PMC), is a promising alternative to vitamin E in clinical applications. Critical vascular inflammation leads to vascular dysfunction and vascular diseases, including atherosclerosis, hypertension and abdominal aortic aneurysms. In this study, we investigated the mechanisms of the inhibitory effects of PMC in vascular smooth muscle cells (VSMCs) exposed to pro‐inflammatory stimuli, lipopolysaccharide (LPS) combined with interferon (IFN)‐γ. Treatment of LPS/IFN‐γ‐stimulated VSMCs with PMC suppressed the expression of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase‐9 in a concentration‐dependent manner. A reduction in LPS/IFN‐γ‐induced nuclear factor (NF)‐κB activation was also observed in PMC‐treated VSMCs. The translocation and phosphorylation of p65, protein phosphatase 2A (PP2A) inactivation and the formation of reactive oxygen species (ROS) were significantly inhibited by PMC in LPS/IFN‐γ‐activated VSMCs. However, neither IκBα degradation nor IκB kinase (IKK) or ribosomal s6 kinase‐1 phosphorylation was affected by PMC under these conditions. Both treatments with okadaic acid, a PP2A‐selective inhibitor, and transfection with PP2A siRNA markedly reversed the PMC‐mediated inhibition of iNOS expression, NF‐κB‐promoter activity and p65 phosphorylation. Immunoprecipitation analysis of the cellular extracts of LPS/IFN‐γ‐stimulated VSMCs revealed that p65 colocalizes with PP2A. In addition, p65 phosphorylation and PP2A inactivation were induced in VSMCs by treatment with H₂O₂, but neither IκBα degradation nor IKK phosphorylation was observed. These results collectively indicate that the PMC‐mediated inhibition of NF‐κB activity in LPS/IFN‐γ‐stimulated VSMCs occurs through the ROS‐PP2A‐p65 signalling cascade, an IKK‐IκBα‐independent mechanism. Therapeutic interventions using PMC may therefore be beneficial for the treatment of vascular inflammatory diseases.     

LIGHT/IFN‐γ triggers β cells apoptosis via NF‐κB/Bcl2‐dependent mitochondrial pathway

LIGHT recruits and activates naive T cells in the islets at the onset of diabetes. IFN‐γ secreted by activated T lymphocytes is involved in beta cell apoptosis. However, whether LIGHT sensitizes IFNγ‐induced beta cells destruction remains unclear. In this study, we used the murine beta cell line MIN6 and primary islet cells as models for investigating the underlying cellular mechanisms involved in LIGHT/IFNγ – induced pancreatic beta cell destruction. LIGHT and IFN‐γ synergistically reduced MIN6 and primary islet cells viability; decreased cell viability was due to apoptosis, as demonstrated by a significant increase in Annexin V⁺ cell percentage, detected by flow cytometry. In addition to marked increases in cytochrome c release and NF‐κB activation, the combination of LIGHT and IFN‐γ caused an obvious decrease in expression of the anti‐apoptotic proteins Bcl‐2 and Bcl‐xL, but an increase in expression of the pro‐apoptotic proteins Bak and Bax in MIN6 cells. Accordingly, LIGHT deficiency led to a decrease in NF‐κB activation and Bak expression, and peri‐insulitis in non‐obese diabetes mice. Inhibition of NF‐κB activation with the specific NF‐κB inhibitor, PDTC (pyrrolidine dithiocarbamate), reversed Bcl‐xL down‐regulation and Bax up‐regulation, and led to a significant increase in LIGHT‐ and IFN‐γ‐treated cell viability. Moreover, cleaved caspase‐9, ‐3, and PARP (poly (ADP‐ribose) polymerase) were observed after LIGHT and IFN‐γ treatment. Pretreatment with caspase inhibitors remarkably attenuated LIGHT‐ and IFNγ‐induced cell apoptosis. Taken together, our results indicate that LIGHT signalling pathway combined with IFN‐γ induces beta cells apoptosis via an NF‐κB/Bcl2‐dependent mitochondrial pathway.