Regulation of NF-kappaB activity by I kappaB-related proteins in adenocarcinoma cells

IKKα plays a major role in canonical NF-kB signalling in colorectal cells

Inhibitor of kappa B (IκB) kinase β (IKKβ) has long been viewed as the dominant IKK in the canonical nuclear factor-κB (NF-κB) signalling pathway, with IKKα being more important in non-canonical NF-κB activation. Here we have investigated the role of IKKα and IKKβ in canonical NF-κB activation in colorectal cells using CRISPR–Cas9 knock-out cell lines, siRNA and selective IKKβ inhibitors. IKKα and IKKβ were redundant for IκBα phosphorylation and turnover since loss of IKKα or IKKβ alone had little (SW620 cells) or no (HCT116 cells) effect. However, in HCT116 cells IKKα was the dominant IKK required for basal phosphorylation of p65 at S536, stimulated phosphorylation of p65 at S468, nuclear translocation of p65 and the NF-κB-dependent transcriptional response to both TNFα and IL-1α. In these cells, IKKβ was far less efficient at compensating for the loss of IKKα than IKKα was able to compensate for the loss of IKKβ. This was confirmed when siRNA was used to knock-down the non-targeted kinase in single KO cells. Critically, the selective IKKβ inhibitor BIX02514 confirmed these observations in WT cells and similar results were seen in SW620 cells. Notably, whilst IKKα loss strongly inhibited TNFα-dependent p65 nuclear translocation, IKKα and IKKβ contributed equally to c-Rel nuclear translocation indicating that different NF-κB subunits exhibit different dependencies on these IKKs. These results demonstrate a major role for IKKα in canonical NF-κB signalling in colorectal cells and may be relevant to efforts to design IKK inhibitors, which have focused largely on IKKβ to date.

Magnetic CuFe2O4 with intrinsic protease-like activity inhibited cancer cell proliferation and migration through mediating intracellular proteins

Protease has been widely used in biological and industrial fields. Developing efficient artificial enzyme mimics remains a major technical challenge due to the high stability of peptide bonds. Nanoenzymes with high stability, high activity and low cost, provided new opportunities to break through natural enzyme inherent limitations. However, compared with many nanomaterials with inherent peroxidase activity, the intrinsic mimic proteases properties of magnetic nanomaterials were seldom explored, let alone the interaction between magnetic nanomaterials and cellular proteins. Herein, we reported for the first time that magnetic CuFe₂O₄ possesses inherent protease activity to hydrolyze bovine serum albumin (BSA) and casein under physiological conditions, and the CuFe₂O₄ is more resistant to high temperature than the natural trypsin. It also exhibited significantly higher catalytic efficiency than other copper nanomaterials and can be recycled for many times. Protease participated in pathophysiological processes and all stages of tumor progression. Interesting, CuFe₂O₄ exhibited anti-proliferative effect on A549, SKOV3, HT-29, BABL-3T3 and HUVEC cells, as well as it was particularly sensitive against SKOV3 cells. CuFe₂O₄ was about 30 times more effective than conventional chemotherapy drugs oxaliplatin and artesunate against SKOV3 cells. In addition, CuFe₂O₄ also mediated the expression of intracellular proteins, such as MMP-2, MMP-9, F-actin, and NF-kB, which may be associated with global protein hydrolysis by CuFe₂O₄, leading to inhibition of cell migration. The merits of the high magnetic properties, good protease-mimic and antitumor activities make CuFe₂O₄ nanoparticles very prospective candidates for many applications such as proteomics and biotechnology.

UBE2S activates NF-κB signaling by binding with IκBα and promotes metastasis of lung adenocarcinoma cells

PURPOSE

Nuclear factor (NF)-κB signaling in cancer cells has been reported to be involved in tumorigenesis. Phosphorylation and degradation of inhibitor of NF-κBα (IκBα) is a canonical pathway of NF-κB signaling. Here, we aimed to identify and characterize noncanonical activation of NF-κB signaling by ubiquitin-conjugating enzyme E2S (UBE2S) in lung adenocarcinoma cells.

METHODS

TCGA and the Human Atlas Protein Database were used to analyze the survival rate of lung adenocarcinoma patients in conjunction with UBE2S expression. In addition, PC9, H460, H441 and A549 lung adenocarcinoma cells were used in this study. PC9 and H460 cells were selected for further analysis because they expressed different UBE2S protein levels. Specific IKK inhibitors, PS1145 and SC514, were used to assess IκBα phosphorylation. Western blot analysis was used to assess protein levels in PC9 and H460 cells. A scratch wound-healing assay was used to analyze the migrative abilities of PC9 and H460 cells. Overexpression and knockdown of UBE2S in H460 and PC9 cells were used to analyze their effects on downstream protein levels. Immunoprecipitation, immunofluorescent staining, glutathione S transferase (GST) pull-down and in vitro binding assays were used to analyze the interaction between UBE2S and IκBα. A luciferase assay was used to analyze activation of NF-κB signaling regulated by UBE2S. An in vivo zebrafish xenograft model was used to assess metastasis of PC9 cells regulated by UBE2S.

RESULTS

We found that UBE2S expression in lung adenocarcinoma patients was negatively related to survival rate. The protein level of UBE2S was higher in PC9 cells than in H460 cells, which was opposite to that observed for IκBα. PC9 cells showed a higher UBE2S expression and migrative ability than H460 cells. Phosphorylation of IκBα was not changed by treatment with the IKK-specific inhibitors PS1145 and SC514 in PC9 and H460 cells. Overexpression and knockdown of UBE2S in H460 and PC9 cells revealed that the protein levels of IκBα were inversely regulated. Immunoprecipitation, immunofluorescent staining, GST pull-down and in vitro binding assays revealed direct binding of UBE2S with IκBα. Nuclear P65 protein levels and luciferase assays showed that NF-κB signaling was regulated by UBE2S. The expression of epithelial-to-mesenchymal (EMT) markers and the migrative ability of lung adenocarcinoma cells were also regulated by UBE2S. A zebrafish xenograft tumor model showed a reduction in the metastasis of PC9 cells that was induced by UBE2S knockdown.

CONCLUSIONS

Higher UBE2S expression in lung adenocarcinomas may lead to increased binding with IκBα to activate NF-κB signaling and promote adenocarcinoma cell metastasis. UBE2S may serve as a potential therapeutic target for lung adenocarcinomas.

Meisoindigo attenuates dextran sulfate sodium-induced experimental colitis via its inhibition of TAK1 in macrophages

At present, inflammatory bowel disease (IBD) seriously threatens human health, and its treatment is a huge challenge for people. In our studies, we found that meisoindigo, a derivative of indirubin, significantly ameliorated dextran sulfate sodium (DSS)-induced experimental colitis in mice. Meisoindigo treatment markedly elevated the level of glutathione, while suppressed the activities of alkaline phosphatase and myeloperoxidase in colonic tissues. Moreover, the mRNA expression of vascular cell adhesion molecule 1, intercellular adhesion molecule 1, cyclooxygenase-2 which are important colitis-related molecules and the levels of the inflammatory cytokines interleukin (IL)-18, IL-1β, IL-6, tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS) were suppressed dose-dependently following treatment with meisoindigo. Immunofluorescence results indicated that meisoindigo inhibited macrophage infiltration and nuclear factor (NF)-κB activation in colons from DSS-treated mice. Therefore, mouse RAW264.7 and human THP-1 cells were treated with lipopolysaccharide (LPS) alone or combined adenosine triphosphate to activate NF-κB pathway in vitro. It was shown that meisoindigo reduced the elevated levels of NO, IL-18, IL-1β and TNF-α after LPS treatment in both cells. In addition, meisoindigo showed inhibitory effects on NF-κB by using a luciferase reporter gene that depends on NF-κB. Through molecular docking, microscale thermophoresis and cellular thermal shift assay. It was further found that meisoindigo targeted transforming growth factor β activated kinase-1 (TAK1), which is an important regulator in the upstream of NF-κB pathway. In conclusion, our findings show that meisoindigo can alleviate IBD effectively at low doses, and negatively regulate proinflammatory responses by inhibiting the activation of TAK1, which provides new ideas for clinical anti-inflammatory therapy.

NF-κB signaling and crosstalk during carcinogenesis

Transcription factors (TFs) are proteins that control the transcription of genetic information from DNA to mRNA by binding to specific DNA sequences either on their own or with other proteins as a complex. TFs thus support or suppress the recruitment of the corresponding RNA polymerase. In general, TFs are classified by structure or function. The TF, Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), is expressed in all cell types and tissues. NF-κB signaling and crosstalk are involved in several steps of carcinogenesis including in sequences involving pathogenic stimulus, chronic inflammation, fibrosis, establishment of its remodeling to the precancerous niche (PCN) and transition of a normal cell to a cancer cell. Triggered by various inflammatory cytokines, NF-κB is activated along with other TFs with subsequent stimulation of cell proliferation and inhibition of apoptosis. The involvement of NF-κB in carcinogenesis provides an opportunity to develop anti-NF-κB therapies. The complexity of these interactions requires that we elucidate those aspects of NF-κB interactions that play a role in carcinogenesis, the sequence of events leading to cancer.

Caffeic acid phenethyl ester attenuates neuropathic pain by suppressing the p38/NF-κB signal pathway in microglia

Background

Management of neuropathic pain is still a clinical challenge. Evidence has accumulated indicating that propolis is effective in attenuating neuropathic pain; however, the mechanism is not fully understood. Our present study investigated the effects and the possible mechanism of caffeic acid phenethyl ester (CAPE), the main ingredient of propolis, in improving neuropathic pain via its inhibition on p38/NF-κB signal pathway in microglia.

Materials and methods

Chronic constriction injury (CCI) mice model and the microglial cell line BV-2 were used to investigate the effects and the mechanism of CAPE. Cell signaling was measured by real-time PCR, Western blotting and immunofluorescence assay.

Results

CAPE relieved neuropathic pain behaviors induced by CCI in mice. CAPE also inhibited CCI-induced activation of microglia. Furthermore, CAPE suppressed the phosphorylation of p38 mitogen-activated protein kinase, inhibited the translocation of NF-κB and decreased the expression of proinflammatory cytokines tumor necrosis factor-α, IL-1β and IL-6.

Conclusion

CAPE was found to be an effective and safe drug candidate for alleviating neuropathic pain by its powerful inhibition on the P38/NF-κB signal pathway.

Alternative NF-κB signaling promotes colorectal tumorigenesis through transcriptionally upregulating Bcl-3

Multiple studies have shown that chronic inflammation is closely related to the occurrence and development of colorectal cancer (CRC). Classical NF-κB signaling, the key factor in controlling inflammation, has been found to be of great importance to CRC development. However, the role of alternative NF-κB signaling in CRC is still elusive. Here, we found aberrant constitutive activation of alternative NF-κB signaling both in CRC tissue and CRC cells. Knockdown of RelB downregulates c-Myc and upregulates p27^Kip1 protein level, which inhibits CRC cell proliferation and retards CRC xenograft growth. Conversely, overexpression of RelB increases proliferation of CRC cells. In addition, we revealed a significant correlation between Bcl-3 and RelB in CRC tissues. The expression of RelB was consistent with the expression of Bcl-3 and the phosphorylation of Bcl-3 downstream proteins p-Akt (S473) and p-GSK3β (S9). Bcl-3 overexpression can restore the phenotype changes caused by RelB knockdown. Importantly, we demonstrated that alternative NF-κB transcriptional factor (p52:RelB) can directly bind to the promoter region of Bcl-3 gene and upregulate its transcription. Moreover, the expression of RelB, NF-κB2 p52, and Bcl-3 was associated with poor survival of CRC patients. Taken together, these results represent that alternative NF-κB signaling may function as an oncogenic driver in CRC, and also provide new ideas and research directions for the pathogenesis, prevention, and treatment of other inflammatory-related diseases.

IRF-1 inhibits NF-κB activity, suppresses TRAF2 and cIAP1 and induces breast cancer cell specific growth inhibition

Interferon Regulatory Factor (IRF)-1, originally identified as a transcription factor of the human interferon (IFN)-β gene, mediates tumor suppression and may inhibit oncogenesis. We have shown that IRF-1 in human breast cancer cells results in the down-regulation of survivin, tumor cell death, and the inhibition of tumor growth in vivo in xenogeneic mouse models. In this current report, we initiate studies comparing the effect of IRF-1 in human nonmalignant breast cell and breast cancer cell lines. While IRF-1 in breast cancer cells results in growth inhibition and cell death, profound growth inhibition and cell death are not observed in nonmalignant human breast cells. We show that TNF-α or IFN-γ induces IRF-1 in breast cancer cells and results in enhanced cell death. Abrogation of IRF-1 diminishes TNF-α and IFN-γ-induced apoptosis. We test the hypothesis that IRF-1 augments TNF-α-induced apoptosis in breast cancer cells. Potential signaling networks elicited by IRF-1 are investigated by evaluating the NF-κB pathway. TNF-α and/or IFN-γ results in decreased presence of NF-κB p65 in the nucleus of breast cancer cells. While TNF-α and/or IFN-γ can induce IRF-1 in nonmalignant breast cells, a marked change in NF-κB p65 is not observed. Moreover, the ectopic expression of IRF-1 in breast cancer cells results in caspase-3, -7, -8 cleavage, inhibits NF-κB activity, and suppresses the expression of molecules involved in the NF-κB pathway. These data show that IRF-1 in human breast cancer cells elicits multiple signaling networks including intrinsic and extrinsic cell death and down-regulates molecules involved in the NF-κB pathway.

DMA(V) in Drinking Water Activated NF-κB Signal Pathway and Increased TGF-β and IL-1β Expressions in Bladder Epithelial Cells of Rats

Dimethylarsinic acid (DMA(V)) is the main product of arsenic methylation metabolism in vivo and is rat bladder carcinogen and tumor promoting agent. In this study, we measured the expressions of mRNA and proteins of NF-κB pathway members, IKKα, IKKβ, p65, and p50 in rat bladder epithelium by qRT-PCR and immunohistochemical analysis after rats received drinking water containing 100 and 200 ppm DMA(V) for 10 weeks. Transforming growth factor-β (TGF-β) immunoexpression in rat bladder epithelium and urine level of IL-1β also were determined. We found that DMA(V) dramatically increased the mRNA levels of NF-κB p50 and IKKα in the bladder epithelium of rats compared to the control group. Immunohistochemical examinations showed that DMA(V) increased immunoreactivities of IKKα, IKKβ, and phospho-NF-κB p50 in the cytoplasm and phospho-NF-κB p50 and p65 in nucleus of rat urothelial cells. In addition, DMA(V) treated rats exhibited significantly increased inflammatory factor TGF-β immunoreactivity in bladder epithelium and IL-1β secretion in urine. These data suggest that DMA(V) could activate NF-κB signal pathway and increase TGF-β and IL-1β expressions in bladder epithelial cells of rats.

IκΒα inhibits apoptosis at the outer mitochondrial membrane independently of NF-κB retention

IκBα resides in the cytosol where it retains the inducible transcription factor NF-κB. We show that IκBα also localises to the outer mitochondrial membrane (OMM) to inhibit apoptosis. This effect is especially pronounced in tumour cells with constitutively active NF-κB that accumulate high amounts of mitochondrial IκBα as a NF-κB target gene. 3T3 IκBα(-/-) cells also become protected from apoptosis when IκBα is specifically reconstituted at the OMM. Using various IκBα mutants, we demonstrate that apoptosis inhibition and NF-κB inhibition can be functionally and structurally separated. At mitochondria, IκBα stabilises the complex of VDAC1 and hexokinase II (HKII), thereby preventing Bax recruitment to VDAC1 and the release of cytochrome c for apoptosis induction. When IκBα is reduced in tumour cells with constitutively active NF-κB, they show an enhanced response to anticancer treatment in an in vivo xenograft tumour model. Our results reveal the unexpected activity of IκBα in guarding the integrity of the OMM against apoptosis induction and open possibilities for more specific interference in tumours with deregulated NF-κB.

Suppression of NF-κB signaling and NLRP3 inflammasome activation in macrophages is responsible for the amelioration of experimental murine colitis by the natural compound fraxinellone

Inflammatory bowel disease (IBD) affects millions of people worldwide. Although the etiology of this disease is uncertain, accumulating evidence indicates a key role for the activated mucosal immune system. In the present study, we examined the effects of the natural compound fraxinellone on dextran sulfate sodium (DSS)-induced colitis in mice, an animal model that mimics IBD. Treatment with fraxinellone significantly reduced weight loss and diarrhea in mice and alleviated the macroscopic and microscopic signs of the disease. In addition, the activities of myeloperoxidase and alkaline phosphatase were markedly suppressed, while the levels of glutathione were increased in colitis tissues following fraxinellone treatment. This compound also decreased the colonic levels of interleukin (IL)-1β, IL-6, IL-18 and tumor necrosis factor (TNF)-α in a concentration-dependent manner. These effects of fraxinellone in mice with experimental colitis were attributed to its inhibition of CD11b(+) macrophage infiltration. The mRNA levels of macrophage-related molecules in the colon, including intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2), were also markedly inhibited following fraxinellone treatment. The results from in vitro assays showed that fraxinellone significantly reduced lipopolysaccharide (LPS)-induced production of nitric oxide (NO), IL-1β and IL-18 as well as the activity of iNOS in both THP-1 cells and mouse primary peritoneal macrophages. The mechanisms responsible for these effects were attributed to the inhibitory role of fraxinellone in NF-κB signaling and NLRP3 inflammasome activation. Overall, our results support fraxinellone as a novel drug candidate in the treatment of colonic inflammation.

Resveratrol reduces morphine tolerance by inhibiting microglial activation via AMPK signalling

BACKGROUND

Evidence has accumulated indicating that microglia within the spinal cord play a critical role in morphine tolerance. The present study investigated the effects and possible mechanisms of 5' adenosine monophosphate-activated protein kinase (AMPK) activator resveratrol and AICAR to inhibit microglial activation and to limit the decrease in antinociceptive effects of morphine.

METHODS

The microglial cell line BV-2 was used. Cytokine expression was measured using quantitative polymerase chain reaction. Cell signalling was assayed by Western blot and immunohistochemistry. The antinociception and morphine tolerance were assessed in CD-1 mice using the hot plate and tail-flick tests.

RESULTS

(1) Morphine induces robust BV-2 cell activation, as evidenced by increased p38 mitogen-activated protein kinase phosphorylation, nuclear factor-κB translocation and mRNA expression of pro-inflammatory cytokines [including interleukin-1β (IL-1β), IL-6 and tumour necrosis factor-α], inducible nitric oxide synthase and Toll-like receptor-4, and these changes are inhibited by resveratrol. (2) Resveratrol activates AMPK to suppress morphine-induced BV-2 cell activation. AICAR, another AMPK activator, can mimic the effects of resveratrol, whereas compound C, an AMPK inhibitor, reverses the inhibitory effects of resveratrol treatment. (3) Systemic or spinal administration of resveratrol with morphine significantly blocks microglial activation in the spinal cord and then attenuates the development of acute and chronic morphine tolerance in both male and female mice.

CONCLUSION

Resveratrol directly suppresses morphine-induced microglial activation through activating AMPK, resulting in significant attenuation of morphine antinociceptive tolerance.

AMR-Me inhibits PI3K/Akt signaling in hormone-dependent MCF-7 breast cancer cells and inactivates NF-κB in hormone-independent MDA-MB-231 cells

AMR-Me, a C-28 methylester derivative of triterpenoid compound Amooranin isolated from Amoora rohituka stem bark and the plant has been reported to possess multitude of medicinal properties. Our previous studies have shown that AMR-Me can induce apoptosis through mitochondrial apoptotic and MAPK signaling pathways by regulating the expression of apoptosis related genes in human breast cancer MCF-7 cells. However, the molecular mechanism of AMR-Me induced apoptotic cell death remains unclear. Our results showed that AMR-Me dose-dependently inhibited the proliferation of MCF-7 and MDA-MB-231 cells under serum-free conditions supplemented with 1 nM estrogen (E2) with an IC50 value of 0.15 µM, 0.45 µM, respectively. AMR-Me had minimal effects on human normal breast epithelial MCF-10A + ras and MCF-10A cells with IC50 value of 6 and 6.5 µM, respectively. AMR-Me downregulated PI3K p85, Akt1, and p-Akt in an ERα-independent manner in MCF-7 cells and no change in expression levels of PI3K p85 and Akt were observed in MDA-MB-231 cells treated under similar conditions. The PI3K inhibitor LY294002 suppressed Akt activation similar to AMR-Me and potentiated AMR-Me induced apoptosis in MCF-7 cells. EMSA revealed that AMR-Me inhibited nuclear factor-kappaB (NF-κB) DNA binding activity in MDA-MB-231 cells in a time-dependent manner and abrogated EGF induced NF-κB activation. From these studies we conclude that AMR-Me decreased ERα expression and effectively inhibited Akt phosphorylation in MCF-7 cells and inactivate constitutive nuclear NF-κB and its regulated proteins in MDA-MB-231 cells. Due to this multifactorial effect in hormone-dependent and independent breast cancer cells AMR-Me deserves attention for use in breast cancer prevention and therapy.

Integrin αvβ3 promotes vitronectin gene expression in human ovarian cancer cells by implicating rel transcription factors

We previously showed that integrin αvβ3 expression upon engagement by its major ligand vitronectin (VN) correlated with enhanced human ovarian cancer cell adhesion, motility, and proliferation, by triggering intracellular signaling events, ultimately leading to altered gene expression. In the present study, we characterized cellular VN expression as a function of αvβ3 and noticed significant upregulation of VN protein which was reflected by elevated VN gene transcription. In order to identify specific transcription factors involved in the αvβ3-regulatory effect on VN, we generated different VN promoter mutants. We noticed that disruption of the DNA consensus motif for Rel proteins did not only prominently reduce VN promoter activity but, moreover, led to a loss of responsiveness to αvβ3, suggesting a crucial role of Rel proteins in αvβ3-provoked VN induction. In cell migration studies, we confirmed increased cell motility as a function of αvβ3/VN which was further enhanced by raising cellular Rel transcription factor levels. Thus, the data of the present study elucidated a positive feedback regulatory loop on VN expression by αvβ3 implicating transcription factors of the Rel family. Hence by altering the composition of the extracellular matrix upon additional VN synthesis and deposition, tumor cells might be enabled to modulate their surrounding reactive microenvironment towards enhanced αvβ3/VN-interactions and, consequently, intrinsic intracellular signaling events affecting cancer progression.

Curcumin promotes apoptosis, increases chemosensitivity, and inhibits nuclear factor kappaB in esophageal adenocarcinoma

The transcription factor, nuclear factor kappaB (NF-kappaB), plays a central role as a key mediator of cell survival and proliferation, and its activation may confer increased tumor chemoresistance. Curcumin, an orally available naturally occurring compound, has been shown to inhibit NF-kappaB and has a potential role in cancer chemoprevention. We investigated the effects of curcumin on NF-kappaB activity, on cell viability, and as a chemosensitizing agent with 5-fluorouracil (5-FU) or cisplatin (CDDP) in esophageal adenocarcinoma (EAC). Oligonucleotide microarray analysis of 46 cases, consisting of Barrett metaplasia, low-grade dysplasia, high-grade dysplasia and EAC, showed increased expression of NF-kappaB and IkappaB kinase subunits and decreased effector caspase expression in EAC compared with Barrett metaplasia. Stromal expression of both IkappaB and phospho-IkappaB was detected in several EAC samples by tissue microarray analysis. Curcumin alone inhibited NF-kappaB activity and induced apoptosis in both Flo-1 and OE33 EAC cell lines as determined by Western blot analysis, NF-kappaB reporter assays, and Caspase-Glo 3/7 assays. It also increased 5-FU- and CDDP-induced apoptosis in both cell lines. These data suggest that activation of NF-kappaB and inhibition of apoptosis may play a role in the progression from Barrett metaplasia to EAC. In addition, curcumin, a well-known inhibitor of NF-kappaB activity, was shown to increase apoptosis and enhance both 5-FU- and CDDP-mediated chemosensitivity, suggesting that it may have potential application in the therapy of patients with EAC.

Basic concepts of inflammation and its role in carcinogenesis

While the normal inflammatory cascade is self-limiting and crucial for host protection against invading pathogens and in the repair of damaged tissue, a wealth of evidence suggests that chronic inflammation is the engine driving carcinogenesis. Over a period of almost 150 years the link between inflammation and cancer development has been well established. In this chapter we discuss the fundamental concepts and mechanisms behind normal inflammation as it pertains to wound healing. We further discuss the association of inflammation and its role in carcinogenesis, highlighting the different stages of cancer development, namely tumour initiation, promotion and progression. With both the innate and adaptive arms of the immune system being central to the inflammatory process, we examine the role of a number of immune effectors in contributing to the carcinogenic process. In addition, we highlight the influences of host genetics in altering cancer risk.

Classical NF-kappaB activation negatively regulates noncanonical NF-kappaB-dependent CXCL12 expression

Ligation of the lymphotoxin-β receptor (LTβR) by LIGHT (lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpes virus entry mediator on T cells (TNFSF14)) activates the noncanonical (NC) NF-κB (nuclear factor-κB) pathway and up-regulates CXCL12 gene expression by human umbilical vein endothelial cells (HUVEC). In contrast, TNF only activates classical NF-κB signaling and does not up-regulate CXCL12. To determine whether cross-talk between the classical and NC pathways affects CXCL12 expression, we investigated the effects of TNF on LIGHT signaling in HUVEC. We show here that TNF inhibits both basal and LIGHT-induced CXCL12 expression. Negative regulation by TNF requires the classical NF-κB pathway as inhibition of basal and induced CXCL12 was reversed in HUVEC-expressing dominant negative IκB (inhibitor of NF-κB) kinase (IKK)β (IKKβ(K44M)). TNF did not inhibit the NC NF-κB pathway activation as LIGHT-induced p100 processing to p52 was intact; however, TNF either alone or together with LIGHT up-regulated p100 and RelB expression and induced the nuclear localization of p100-RelB complexes. Enhanced p100 and RelB expression was inhibited by IKKβ(K44M), which led us to question whether the IκB function of elevated p100 mediates the inhibition of CXCL12 expression by TNF. We retrovirally transduced HUVEC to express p100 at a level similar to that up-regulated by TNF; however, basal and LIGHT-induced CXCL12 expression was normal in the transduced cells. In contrast, ectopic RelB expression recapitulated the effects of TNF on NC signaling and inhibited basal and LIGHT-induced CXCL12 expression by HUVEC. Our findings therefore demonstrate that TNF-induced classical NF-κB signaling up-regulates RelB expression that inhibits both basal and NC NF-κB-dependent CXCL12 expression.

Brucea javanica oil induces apoptosis in T24 bladder cancer cells via upregulation of caspase-3, caspase-9, and inhibition of NF-kappaB and COX-2 expressions

The potential molecular mechanism of Brucea javanica oil in the induction of apoptosis of T24 bladder cancer cells was investigated in vitro. T24 cells were divided into two groups: one, treated with B. javanica oil and the other, untreated. The cells were maintained in Dulbecco's modified Eagle's medium (DMEM) containing 10% fetal calf serum (FCS) and 4 mM glutamine. The morphological characteristics of T24 cells were examined microscopically at the 2nd and 5th day of the culture. The drug toxicity spectrum (IC(50)) was estimated by the MTT assay, and viability of T24 cells was assessed on the basis of the percentage of T24 apoptotic cells, as determined by Annexin/PI staining and flow cytometric analysis. The expression of caspase-3, capase-9, NF-kappaB p65, and COX-2 was analyzed by Western blotting. Morphological characteristics of the cells on the 2nd day showed apoptosis of the treated T24 cells; it was more apparent in the cells on the 5th day. B. javanica oil decreased the cell viability at the testing concentrations spectrum (5-0.156 mg/ml), and this viability was significantly higher as compared to the control group. In this concentration spectrum, B. javanica oil also induced apoptosis of T24 cells, which was analyzed by annexin/PI staining and flow cytometric analysis. These results were also statistically significant as compared to those of the control group. The expressions of caspase-3 and caspase-9 were low in the control T24 cells, while the expressions of NF-kappaB and COX-2 were high in normal T24 cells. Treatment with B. javanica oil significantly induced the expressions of caspase-3 and caspase-9 proteins in T24 cells, whereas the expressions of NF-kappaB and COX-2 proteins were inhibited. B. javanica oil significantly reduced the viability of T24 cells and induced T24 cell apoptosis. The molecular mechanism underlying these effects may be the activation of caspase apoptotic pathway by upregulation of the expression of caspase-3 and caspase-9 proteins and inhibition of the expression of NF-kappaB and COX-2 proteins.

The repressing function of the oncoprotein BCL-3 requires CtBP, while its polyubiquitination and degradation involve the E3 ligase TBLR1

The nuclear and oncogenic BCL-3 protein activates or represses gene transcription when bound to NF-kappaB proteins p50 and p52, yet the molecules that specifically interact with BCL-3 and drive BCL-3-mediated effects on gene expression remain largely uncharacterized. Moreover, GSK3-mediated phosphorylation of BCL-3 triggers its degradation through the proteasome, but the proteins involved in this degradative pathway are poorly characterized. Biochemical purification of interacting partners of BCL-3 led to the identification of CtBP as a molecule required for the ability of BCL-3 to repress gene transcription. CtBP is also required for the oncogenic potential of BCL-3 and for its ability to inhibit UV-mediated cell apoptosis in keratinocytes. We also defined the E3 ligase TBLR1 as a protein involved in BCL-3 degradation through a GSK3-independent pathway. Thus, our data demonstrate that the LSD1/CtBP complex is required for the repressing abilities of an oncogenic I kappaB protein, and they establish a functional link between the E3 ligase TBLR1 and NF-kappaB.

NF-kappaB signalling proteins p50/p105, p52/p100, RelA, and IKKepsilon are over-expressed in oesophageal squamous cell carcinomas

AIMS

Nuclear factor-kappa B (NF-kappaB) activation has been recognised as an important mechanism in the development of cancers. However, expression status of NF-kappaB-related proteins in oesophageal squamous cell carcinoma (ESCC) tissues is largely unknown. In this study, we analysed expressions of NF-kappaB members (p50/105, p52/p100 and RelA) and IKKepsilon in ESCC tissues.

METHODS

We analysed the expression of p50/105, p52/p100, RelA and IKKepsilon in 58 ESCC patients' tissues by immunohistochemistry using a tissue microarray (TMA) method.

RESULTS

Normal oesophageal squamous cells expressed p50/105, p52/p100 and RelA in 5%, 79% and 10% of the tissues in cytoplasm, respectively; however, only p52/p100 was expressed in the nuclei (12%). The cancer tissues expressed p50/105, p52/p100 and RelA in 93%, 95% and 95% in cytoplasm and/or nuclei, respectively. Nuclear immunostainings of NF-kappaB members p50/105, p52/p100 and RelA, which are considered activation of NF-kappaB signalling, were observed in 34%, 60% and 26% of the cancers, respectively. IKKepsilon is expressed in cytoplasm in 50% of the normal squamous tissues and 84% of the cancer tissues. However, none of the expression of p50/105, p52/p100, RelA or IKKepsilon was associated with pathological characteristics, including differentiation, depth of invasion and TNM stage.

CONCLUSION

The increased nuclear expressions of p50/105, p52/p100 and RelA as well as increased cytoplasmic expression of IKKepsilon in the ESCC tissues compared to the normal squamous cells suggested that over-expression of these proteins may be related to activation of the NF-kappaB pathway and might play a role in the development of ESCC.

Expression of CARD6, an NF-kappaB activator, in gastric, colorectal and oesophageal cancers

AIMS

Activation of nuclear factor-kappa B (NF-kappaB) signalling is considered a crucial mechanism in the development of cancers. Caspase-associated recruitment domain 6 (CARD6) is a protein that activates NF-kappaB signalling evoked by RIP1, RIP2, Bcl-10 and MEKK. In this study, we analysed tissue expression of CARD6 protein in oesophageal squamous cell carcinoma (ESCC), gastric adenocarcinomas (GC) and colorectal adenocarcinomas (CRC).

METHODS

We analysed the expression of CARD6 protein in 58 ESCC, 100 GC and 103 CRC patients' tissues by immunohistochemistry using a tissue microarray (TMA) approach.

RESULTS

We found CARD6 immunostaining in cancer cells of ESCC (41/58; 70.7%), GC (45/100; 45.0%) and CRC (81/103; 78.6%). In the GC, intestinal-type GC (77.8%) showed higher expression of CARD6 than diffuse-type GC (20.0%) and mixed-type GC (50.0%). By contrast, corresponding normal epithelial cells of oesophagus (0%), stomach (8.0%) and colon (5.0%) displayed lower frequencies of CARD6 immunostaining. The CARD6 immunostaining was observed in nucleus/cytoplasm (ESCC) or cytoplasm (GC and CRC). The CARD6 expression was evident from an early TNM stage (stage I).

CONCLUSION

The increased expression of CARD6 in ESCC, GC and CRC tissues compared to their corresponding normal cells suggested that neoexpression of CARD6 might be related to activation of NF-kappaB pathway in the cancers and might play a role in the development of most types of gastrointestinal cancers.

Differential effects of NOD2 polymorphisms on colorectal cancer risk: a meta-analysis

INTRODUCTION

Since Kurzawski et al. described an association between the 3020insC NOD2 single nucleotide polymorphism and the risk of colorectal cancer(CRC) in 2004, reports published in the past several years have controversial results regarding the relationship between the development of CRC and NOD2 gene polymorphisms. To clarify the potential role of NOD2 P286S, R702W, G908R, and 3020insC polymorphisms in CRC patients, we have undertaken a systematic review and meta-analysis of published articles.

MATERIALS AND METHODS

Studies reporting on NOD2 polymorphisms and CRC were searched in the PubMed, EMBASE, and the Science Citation Index from the inception of each database to May, 2009. The search strategy included the keywords "CRC", "colon cancer", "rectal cancer", "polymorphism", and "NOD2/CARD15".

RESULT

Eight eligible case-control studies about Caucasians from four countries contributed data on 5,888 subjects (cases: 3,524; controls: 2,364). Compared to the wild genotype, the R702W, G908R, and 3020insC polymorphisms were associated with an increased risk of CRC (odds ratio (OR): 1.59, 1.98, 1.44; 95% confidence interval (CI): 1.09-2.32, 1.14-3.44, 1.13-1.84; P = 0.02, 0.01, 0.003). However, P268S polymorphism did not influence CRC risk (OR: 1.27; CI: 0.32-5.00; P = 0.73).

CONCLUSIONS

These findings indicate that NOD2 R702W, G908R, and 3020insC polymorphisms contribute to CRC susceptibility in Caucasians. Meta-analysis of these polymorphisms in NOD2 gene will help determine their role in CRC carcinogenesis.

Investigation into the controversial association of Streptococcus gallolyticus with colorectal cancer and adenoma

Background

The seroprevalence of IgG antibodies of Streptococcus gallolyticus subspecies gallolyticus, CIP 105428, was evaluated to investigate the controversial association of S. gallolyticus with colorectal carcinoma and adenoma in attempt to investigate the nature of such association if any, by exploring the mRNA expression of NF-κB and IL-8. Moreover, the serological behavior of S. gallolyticus IgG antibodies was compared to that of an indicator bacterium of bowel, Bacteroides fragilis.

Methods

ELISA was used to measure IgG antibodies of S. gallolyticus and B. fragilis in sera of 50 colorectal cancer, 14 colorectal adenoma patients, 30 age- and sex- matched apparently healthy volunteers (HV) and 30 age- and sex- matched colonoscopically-proven tumor-free control subjects. NF-κB and IL-8 mRNA expression was evaluated in tumorous and non-tumorous tissue sections of carcinoma and adenoma patients in comparison with that of control subjects by using in situ hybridization assay.

Results

Colorectal cancer and adenoma patients were associated with higher levels of serum S. gallolyticus IgG antibodies in comparison with HV and control subjects (P < 0.05) while no similar association was found with serum IgG antibodies of B. fragilis (P > 0.05). ELISA cutoff value for the seropositivity of S. gallolyticus IgG was calculated from tumor-free control group. The expression of NF-κB mRNA was higher in tumorous than non-tumorous tissue sections of adenoma and carcinoma, higher in carcinoma/adenoma sections than in control subjects, higher in tumorous sections of carcinoma than in adenoma patients, and higher in S. gallolyticus IgG seropositive than in seronegative groups in both tumorous and non-tumorous sections (P < 0.05). IL-8 mRNA expression in tumorous sections of adenoma and carcinoma was higher than in non-tumorous sections, higher in carcinoma/adenoma than in control subjects, and higher in S. gallolyticus IgG seropositive than in seronegative groups in tumorous rather than non-tumorous sections (P < 0.05).

Conclusion

S. gallolyticus most likely plays an essential role in the oncogenic progression of normal colorectal mucosa to adenoma and to CRC. This promoting/propagating role of S. gallolyticus might take place by utilizing certain inflammatory, anti-apoptotic, and angiogenic factors of transformation including NF-κB and IL-8.

Identification of a small molecule inhibitor of serine 276 phosphorylation of the p65 subunit of NF-kappaB using in silico molecular docking

NF-kappaB is activated in many types of cancer. Phosphorylation of p65 at serine 276 is required for the expression of a subset of NF-kappaB regulated genes, including vascular cell adhesion molecule-1 (VCAM-1) and interleukin-8 (IL-8). Thus, inhibition of serine 276 phosphorylation may prevent metastasis and angiogenesis in certain tumor types. Using in silico molecular docking, small molecules that are predicted to bind to a structural pocket near serine 276 were identified. One compound, NSC-127102, hinders serine 276 phosphorylation and the expression of IL-8 and VCAM-1. Small molecules such as NSC-127102 may be optimized for the future treatment of cancer.

Constitutive non-canonical NFkappaB signaling in pancreatic cancer cells

Constitutive classical NFkappaB activation has been implicated in the development of pancreatic cancer, and inhibition of classical NFkappaB signaling sensitizes pancreatic cancer cells to apoptosis. However, the role of the more recently described non-canonical NFkappaB pathway has not been specifically addressed in pancreatic cancer. The non-canonical pathway requires stabilization of NIK and IKKalpha-dependent phosphorylation and processing of NFkappaB2/p100 to p52. This leads to the activation of p52-RelB heterodimers that regulate genes encoding lymphoid-specific chemokines and cytokines. We performed qRT-PCR to detect gene expression in a panel of pancreatic ductal adenocarcinoma cell lines (BxPC-3, PCA-2, PANC-1, Capan-1, Hs-766T, AsPC-1, MiaPACA-2) and found only modest elevation of classical NFkappaB-dependent genes. In contrast, each of the tumor cell lines displayed dramatically elevated levels of subsets of the non-canonical NFkappaB target genes CCL19, CCL21, CXCL12, CXCL13 and BAFF. Consistent with activation of the non-canonical pathway, p52 and RelB co-localized in adenocarcinoma cells in sections of pancreatic tumor tissue, and each of the tumor cell lines displayed elevated p52 levels. Furthermore, p52 and RelB co-immunoprecipitated from pancreatic cancer cells and immunoblotting revealed that NIK was stabilized and p100 was constitutively phosphorylated in a subset of the cell lines. Finally, stable overexpression of dominant negative IKKalpha significantly inhibited non-canonical target gene expression in BxPC-3 cells. These findings therefore demonstrate that the non-canonical NFkappaB pathway is constitutively active and functional in pancreatic cancer cells.

Radiosensitization of HT-29 cells and xenografts by the nitric oxide donor DETANONOate

BACKGROUND

Mechanisms of radioresistance in rectal cancer remain unclear.

OBJECTIVES

To determine mechanisms of radioresistance in rectal cancer cells and to assess the role of the nitric oxide donor DETANONOate as a radiosensitizing agent.

METHODS

Survival was determined by clonogenic assays, apoptosis by PARP-1 cleavage, and phenotypic differences by Western blot analysis. SCID mice bearing HT-29 xenografts were treated with ionizing radiation (IR) [2.0 Gy x 5], DETANONOate [0.4 mg/kg i.p.], or combination treatment.

RESULTS

Colorectal cancer HT-29-p53-null cells were resistant and HCT-116-p53 wild-type cells sensitive to IR, which correlated with cleaved PARP-1. Increased levels of p21 occurred in HCT-116 cells, while Bcl-2 and survivin were elevated in HT-29 cells. Radiosensitization was achieved with a substantial elevation of cleaved PARP-1 in DETANONOate-HT-29-treated versus control cells, which was accompanied by elevation of p21, p27, and BAX, and a concomitant decrease in Bcl-2. SCID mice bearing HT-29 xenografts demonstrated a 37.6%, 51.1%, and 70.1% inhibition in tumor growth in mice receiving IR, DETANONOate, and combination treatment versus control, respectively.

CONCLUSIONS

Radioresistant HT-29 cells are p53-null and have substantially decreased levels of p21. DETANONOate radiosensitized HT-29 cells in vitro and in vivo by an additive effect in apoptosis.

Identification of a potent herbal molecule for the treatment of breast cancer

BACKGROUND

Breast cancer (BCa)-related mortality still remains the second leading cause of cancer-related deaths worldwide. Patients with BCa have increasingly shown resistance and high toxicity to current chemotherapeutic drugs for which identification of novel targeted therapies are required.

METHODS

To determine the effect of PDBD on BCa cells, estrogen-receptor positive (ER+)-MCF-7 and estrogen-receptor negative (ER-)-MDA 231 cells were treated with PDBD and the cell viability, apoptotic, cell cycle, Western blot and Promoter assays were performed.

RESULTS

PDBD inhibits cell viability of ER+ and ER- BCa cells by inducing apoptosis without causing significant toxicity in normal breast epithelial cells. While dissecting the mechanism of action of PDBD on BCa, we found that PDBD inhibits Akt signaling and its downstream targets such as NF-kappaB activation, IAP proteins and Bcl-2 expression. On the other hand, activation of JNK/p38 MAPK-mediated pro-apoptotic signaling was observed in both ER+ and ER- BCa cells.

CONCLUSION

These findings suggest that PDBD may have wide therapeutic application in the treatment of BCa.

Anti-NF-kappaB and anti-inflammatory activities of synthetic isothiocyanates: effect of chemical structures and cellular signaling

Many cancer chemopreventive agents have been associated with lower cancer risk by suppressing nuclear factor-kappaB (NF-kappaB) signaling pathways, which subsequently leads to attenuated pro-inflammatory mediators and activities. Of the natural compounds, the isothiocyanates (ITCs) found in cruciferous vegetables have received particular attention because of their potential anti-cancer effects. However, limited studies regarding the influence of ITCs structure on NF-kappaB transactivation and anti-inflammatory action are reported. In the present study, the anti-inflammatory potential of ten structurally divergent synthetic ITCs were evaluated in HT-29-N9 human colon cancer cells and RAW 264.7 murine macrophages. The effect of ITCs on the basal transcriptional activation of NF-kappaB and the inflammatory response to bacterial lipopolysaccharide (LPS) were assessed. The synthetic ITC analogs suppressed NF-kappaB-mediated pro-inflammatory gene transcription. Among the ITC analogs, tetrahydrofurfuryl isothiocyanate, methyl-3-isothiocyanatopropionate, 3-morpholinopropyl isothiocyanate and 3,4-methyelendioxybenzyl isothiocyanate showed stronger NF-kappaB inhibition as compared to the parent compound, phenylethyl isothiocyanate (PEITC). Molecular analysis revealed that several of the pro-inflammatory mediators and cytokines (iNOS, COX-2, IL-1beta, IL-6 and TNF-alpha) were reduced by ITCs, and correlated with the downregulation of NF-kappaB signaling pathways. Immunoblotting showed that ITCs suppressed LPS-induced phosphorylation and degradation of IkappaB alpha and decreased nuclear translocation of p65. In parallel, ITCs suppressed the phosphorylation of IkappaB kinase alpha/beta (IKKalpha/beta). Taken together, our findings provide the possibility that synthetic ITC analogs might have promising cancer chemopreventive potential, based on their stronger anti-NF-kappaB and anti-inflammatory activities, than the natural ITCs.

TNF/IL-1/NIK/NF-kappa B transduction pathway: a comparative study in normal and pathological human prostate (benign hyperplasia and carcinoma)

AIMS

Tumour necrosis factor (TNF)-alpha induces death or cell proliferation by activation of nuclear factor (NF)-kappaB, also activated by interleukin (IL)-1 alpha. The aim was to investigate upstream and downstream components of NIK transduction pathway in normal (NP), benign prostatic hyperplasia (BPH), prostatic intraepithelial neoplasia (PIN) and prostatic carcinoma (PC).

METHODS AND RESULTS

Immunohistochemistry and Western blotting were performed. In NP, the cytoplasm of epithelial cells was intensely immunoreactive to IL-1 receptor-associated kinase (IRAK), TNF receptor-associated factor (TRAF)-6, NF-kappaB inducing kinase (NIK), I kappa kappa alpha/beta, I kappaB alpha and p-I kappaB; weakly to NF-kappaB-p50; and negative to NF-kappaB-p65. BPH samples were intensely immunoreactive to IRAK, TRAF-6, NIK, I kappa kappa alpha/beta, I kappaB alpha, p-I kappaB; weakly to NF-kappaB-p50 and NF-kappaB-p65. Whereas low-grade PIN showed intermediate results between NP and BPH, results in high-grade PIN were similar to those found in PC (low Gleason). In PC, immunoreactivity was intense for IRAK, TRAF-6, NIK, I kappa kappa alpha/beta (increasing with Gleason), I kappaB alpha, p-I kappaB (decreasing with Gleason); weak for NF-kappaB-p50 and NF-kappaB-p65 (decreasing with Gleason). Nuclear NF-kappaB was observed in PC.

CONCLUSIONS

NF-kappaB enhances cell proliferation, but also ATF-2 or Elk-1. Since IL-1 and TNF-alpha are related to inflammation and their immunoexpression increases in PC, inhibition of these cytokines might be a possible target for PC treatment, because they decrease the activity of all transduction pathway members that activate transcription factors such as NF-kappaB, Elk-1 or ATF-2.

Clinical significance of nuclear factor (NF)-kappaB levels in urothelial carcinoma of the urinary bladder

Nuclear factor (NF)-kappaB has been reported to be constitutively activated in various human neoplasms. However, its clinical significance in bladder urothelial carcinoma (UC) remains an unresolved issue. We conducted this study trying to elucidate the role of NFkappaB in bladder UC and its potential prognostic significance, by quantifying immunohistochemically the levels of p65/RelA expression in paraffin-embedded tissue from 116 patients. Some of the cases had previously been stained for cellular FLICE-like inhibitory protein (c-FLIP) and bcl-2. Seventy-four cases displayed concurrent cytoplasmic and nuclear immunoreactivity, whereas 18 only nuclear immunoexpression and 21 only cytoplasmic immunoexpression, and the remaining three cases were negative for p65/RelA. Nuclear p65/RelA expression was positively associated with tumour grade and T-category (p=0.0001 in both cases). In addition, cytoplasmic p65/RelA expression was lower in advanced T-category (p=0.0030). Moreover, p65/RelA nuclear expression was positively correlated with c-FLIP (p=0.0109) and bcl-2 (p=0.0452). p65/RelA nuclear expression adversely affected survival in both univariate and multivariate analysis in superficial (Ta-T1; p=0.0010 and p=0.0008) as well as in muscle-invasive carcinomas (T2-T4; p=0.0004 and p=0.0003). Our results demonstrate that NF-kappaB nuclear expression is correlated with histologic grade and T category in bladder UC. Moreover, NF-kappaB nuclear expression emerges as an independent prognosticator of adverse significance, conveying information beyond that obtained by standard clinicopathological prognosticators.

Genetic aspects of inflammation and cancer

Chronic inflammation is involved in the pathogenesis of most common cancers. The aetiology of the inflammation is varied and includes microbial, chemical and physical agents. The chronically inflamed milieu is awash with pro-inflammatory cytokines and is characterized by the activation of signalling pathways that cross-talk between inflammation and carcinogenesis. Many of the factors involved in chronic inflammation play a dual role in the process, promoting neoplastic progression but also facilitating cancer prevention. A comprehensive understanding of the molecular and cellular inflammatory mechanisms involved is vital for developing preventive and therapeutic strategies against cancer. The purpose of the present review is to evaluate the mechanistic pathways that underlie chronic inflammation and cancer with particular emphasis on the role of host genetic factors that increase the risk of carcinogenesis.

Nuclear factor-kappaB activation: from bench to bedside

Nuclear factor-kappaB (NF-kappaB) is a proinflammatory transcription factor that has emerged as an important player in the development and progression of malignant cancers. NF-kappaB targets genes that promote tumor cell proliferation, survival, metastasis, inflammation, invasion, and angiogenesis. Constitutive or aberrant activation of NF-kappa is frequently encountered in many human tumors and is associated with a resistant phenotype and poor prognosis. The mechanism of such persistent NF-kappaB activation is not clear but may involve defects in signaling pathways, mutations, or chromosomal rearrangements. Suppression of constitutive NF-kappaB activation inhibits the oncogenic potential of transformed cells and thus makes NF-kappaB an interesting new therapeutic target in cancer.

Hypoxia regulates iNOS expression in human normal peritoneal and adhesion fibroblasts through nuclear factor kappa B activation mechanism

OBJECTIVE

To determine the mechanism by which hypoxia increases expression of iNOS in human normal peritoneal and adhesion fibroblasts.

DESIGN

Prospective experimental study.

SETTING

University medical center.

PATIENT(S)

Primary cultures of fibroblasts from normal peritoneum and adhesion tissues.

INTERVENTION(S)

Hypoxia-treated cells.

MAIN OUTCOME MEASURE(S)

We used real-time reverse transcription-polymerase chain reaction to quantify mRNA levels of iNOS and nuclear factor kappa B (NF-kappaB). Western blots were used to determine iNOS, NF-kappaB, IkappaB-alpha, and phospho-IkappaB expression levels in normal peritoneal and adhesion fibroblasts in response to hypoxia.

RESULT(S)

Hypoxia resulted in a significant increase in iNOS and NF-kappaB expression in normal and adhesion fibroblasts. Furthermore, both cell types manifested lower levels of NF-kappaB, cytoplasmic phospho-IkappaB-alpha, and iNOS proteins. In contrast, they manifested higher levels of cytoplasmic IkappaB-alpha and IkappaB-alpha/NF-kappaB ratios as well as a phosphorylated-IkappaB-alpha/NF-kappaB ratio. Under hypoxic conditions, both cell types exhibited significantly decreased cytoplasmic NF-kappaB, IkappaB-alpha levels, and significantly increased cytoplasmic phospho-IkappaB-alpha, iNOS, and NF-kappaB protein levels.

CONCLUSION(S)

Hypoxia increases iNOS expression by a mechanism involving activation of NF-kappaB. The ratio of IkappaB-alpha/NF-kappaB or IkappaB-alpha/p-IkappaB-alpha can be used to monitor activation.

NF-kappaB as a molecular target in the therapy of pancreatic carcinoma

The constitutive activation of the transcription factor nuclear-factor kappa B (NF-kappaB) is a hallmark of many highly malignant tumours such as the pancreatic ductal adenocarcinoma and accounts for profound chemoresistance. Inhibition of NF-kappaB activation has been shown to be a useful strategy for increasing the sensitivity towards cytostatic drug treatment in vitro and in vivo. Moreover, various pharmacological substances (e.g. thalidomide, bortezomib, sulphasalazine) have already entered clinical studies partially showing promising results for certain types of cancer. Further studies will be needed, in particular for pancreatic ductal adenocarcinoma, to evaluate the therapeutic efficacy of appropriate combinations of a NF-kappaB inhibitor and cytostatic drugs.

Expression of nuclear factor kappaB in human gastric carcinoma: relationship with I kappaB a and prognostic significance

Nuclear factor (NF)-kappaB is a transcription factor constitutively activated in various neoplasms, including gastric carcinoma. However, its clinical significance in the latter remains an unresolved issue, as published information is limited and controversial. Furthermore, no data is available about the interaction of NF kappaB with its inhibitory protein I kappaB a in gastric carcinoma cases. In this study, the expression of NF kappaB 1/p50 and p I kappaB a protein was evaluated immunohistochemically in paraffin-embedded tissues from 93 patients. The effect of NF kappaB 1/p50 and p I kappaB a on clinical outcome was assessed. Positive immunostaining was detected for nuclear NF kappaB 1/p50, cytoplasmic NF kappa B1/p50 and p I kappaB a in 91, 68 and 85.7% of cases, respectively. A positive correlation emerged between nuclear NF kappa B 1/p50 and p I kappaB a (p < 0.0001) and a negative one between cytoplasmic NF kappaB 1/p50 and p I kappaB a (p = 0.0033). Nuclear NF kappaB 1/p50 was associated with stage (p = 0.0388), the depth of invasion (p = 0.0382), World Health Organization (WHO; p = 0.0326) and Lauren's histological classification (p = 0.0046). NF kappaB 1/p50 nuclear expression adversely affected survival in both univariate and multivariate analysis (p < 0.0001 and p = 0.02, respectively). Our results suggest that NF kappaB 1/p50 nuclear expression and therefore activation is regulated by its interaction with I kappaB a and that the former may serve as a useful independent molecular marker for stratifying patients with gastric carcinoma in terms of prognosis.

Cell death in NF-kappaB-dependent tumour cell lines as a result of NF-kappaB trapping by linker-modified hairpin decoy oligonucleotide

The transcription factor NF-kappaB is frequently activated in cancer, and is therefore a valuable target for cancer therapy. Decoy oligodeoxynucleotides (ODNs) inhibit NF-kappaB by preventing its binding to the promoter region of target genes. Few studies have used NF-kappaB-targeting with ODNs in cancer. Using a hairpin NF-kappaB-decoy ODN we found that it induced growth inhibition and cell death in NF-kappaB-dependent tumour cell lines. The ODN colocalized with the p50 subunit of NF-kappaB in cells and directly interacted with it in nuclear extracts. In TNFalpha-treated cells the ODN and the p50 subunit were found in the cytoplasm suggesting that the complex did not translocate to the nucleus. Transcriptional activity of NF-kappaB was efficiently inhibited by the ODN, whereas a scrambled ODN was without effect on transcription. Thus, ODN-mediated inhibition of NF-kappaB can efficiently promote cell death in cancer cells providing a potentially powerful approach to tumour growth inhibition.

The potential of proteasome inhibition in the treatment of colon cancer

Proteasome inhibition is an entirely novel approach to the treatment of malignant disease. By interfering with the ubiquitin-proteasome degradation system, proteasome inhibitors affect numerous cellular processes that are commonly deregulated in cancer cells including gene transcription, cell-cycle regulation, apoptosis, cell migration and DNA repair. This review outlines the physiology of the ubiquitin-proteasome pathway, discusses preclinical and clinical data regarding the activity of proteasome inhibitors against colon cancer and evaluates the rationale for the use of proteasome inhibitors as monotherapy or in combination with other anticancer therapies (i.e., chemotherapy, radiation therapy and other molecular-targeted therapies) in colon cancer.

Effects of IkappaBalpha and its mutants on NF-kappaB and p53 signaling pathways

AIM

To study the effects of IkappaBalpha and its mutants (IkappaBalphaM, IkappaBalpha243N, IkappaBalphaM244C) on NF-kappaB, p53 and their downstream target genes. The relationship of NF-kappaB, p53, and IkappaBalpha was further discussed.

METHODS

pECFP-IkappaBalpha, pECFP-IkappaBalphaM (amino acides 1-317, Ser32, 36A), pECFP-IkappaBalpha243N (amino acides 1-243), pECFP-IkappaBalpha244C (amino acides 244-317), pEYFP-p65 and pp53-DsRed were constructed and transfected to ASTC-alpha-1 cells. Cells were transfected with pECFP-C1 as a control. 30 h after the transfection, location patterns of NF-kappaB, p53 and IkappaBalpha (IkappaBalphaM, IkappaBalpha243N, IkappaBalpha244C) were observed by a laser scanning microscope (LSM510/ConfoCor2, Zeiss). RNA extraction and reverse transcription were performed in cells transfected or co-transfected with different plasmids. Effects of IkappaBalpha and its mutants on the transprition level of NF-kappaB, NF-kappaB downstream target gene TNF-alpha, p53 and p53 downstream target gene Bax were observed by real time QT-PCR. In all experiments beta-actin was reference. Results are expressed as the target/reference ratio of the sample divided by the target/reference ratio of the control. Different transfected cells were incubated with CCK-8 for 2 h in the incubator. Then the absorbance at 450 nm was measured by using a microplate reader.

RESULTS

Cells that were transfected with p53-DsRed revealed a predominant nuclear localization. YFP-p65 mainly existed in the cytoplasm. Cells were transfected with CFP-IkappaBalpha, CFP-IkappaBalphaM, and CFP-IkappaBalpha243N respectively and revealed a predominant cytosolic localization. However, cells transfected of CFP-IkappaBalpha244C revealed a predominant nuclear localization. The mRNA levels of p65, TNF-alpha, p53 and Bax in CFP-IkappaBalpha transfected cells did not change significantly, while in YFP-p65/CFP-IkappaBalpha co-transfected cells, IkappaBalpha decreased the transcription of p65 downstream gene TNF-alpha (2.24+/-0.503) compared with the YFP-p65/CFP-C1 co-transfected cells (5.08+/-0.891) (P<0.05). Phosphorylation defective IkappaBalpha (IkappaBalphaM) decreased the transcription levels of all the four genes compared with the control (P<0.05). The N terminus of IkappaBalpha (IkappaBalpha243N) increased the transcription of NF-kappaB (1.84+/-0.176) and TNF-alpha (1.51+/-0.203) a little bit. However, the C terminus of IkappaBalpha (IkappaBalpha244C) increased the transcription of NF-kappaB, TNF-alpha, p53 and Bax significantly (8.29+/-1.662, 14.16+/-2.121, 10.2+/-0.621, 3.72+/-0.346) (P<0.05). The CCK-8 experiment also showed that IkappaBalpha244C and p53 synergistically mediate apoptosis.

CONCLUSIONS

IkappaBalpha and its mutants (IkappaBalphaM, IkappaBalpha243N, IkappaBalphaM244C) have different effects on NF-kappaB and p53 signaling pathways, according to their different structures. IkappaBalphaM bounds with NF-kappaB and p53 in cytoplasm steadily, and inhibits both of the two signaling pathways. p53 and IkappaBalpha244C may be co-factor in inducing apoptosis. The C terminal of IkappaBalpha enhanced cell death, which suggests that it may be a pro-apoptotic protein existed in cells.

NF-κB in solid tumors

Cancer is a multistep process during which cells acquire genetic alterations that drive the progressive transformation of normal cells into highly malignant cells. Self-sufficiency in growth, insensitivity to anti-growth signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, tissue invasion and metastasis, are signatures of transformed cells. NF-kappaB is a key actor in tumorigenesis given its ability to control the expression and the function of a number of genes involved in these processes. Indeed, constitutive activation of NF-kappaB is a common feature of many human tumors, while its sustained activation during inflammation predisposes normal cells to neoplastic transformation. Since suppression of NF-kappaB has been shown to inhibit oncogenic potential of transformed cells, targeting it should be effective in the prevention and treatment of cancer.

The alternative NF-kappaB pathway from biochemistry to biology: pitfalls and promises for future drug development

The past two decades have led to a tremendous work on the transcription factor NF-kappaB and its molecular mechanisms of activation. The nuclear translocation of NF-kappaB is controlled by two main pathways: the classical and the alternative NF-kappaB pathways. The classical NF-kappaB pathway activates the IKK complex that controls the inducible degradation of most IkappaB family members that are IkappaBalpha, IkappaBbeta, IkappaBvarepsilon and p105. The alternative NF-kappaB pathway induces p100 processing and p52 generation through the activation of at least two kinases, which are NIK and IKKalpha. Genetic studies have shown that IKKgamma is dispensable for the alternative pathway, which suggests the existence of an alternative IKKalpha-containing complex. It is noteworthy that activation of particular p52 heterodimers like p52/RelB requires solely the alternative pathway while activation of p52/p65 or p52/c-Rel involves a "hybrid pathway". Among others, LTbetaR, BAFF-R, CD40 and RANK have the ability to induce the alternative pathway. The latter plays some roles in biological functions controlled by these receptors, which are the development of secondary lymphoid organs, the proliferation, survival and maturation of B cell, and the osteoclastogenesis. Exacerbated activation of the alternative pathway is potentially associated to a wide range of disorders like rheumatoid arthritis, ulcerative colitis or B cell lymphomas. Therefore, inhibitors of the alternative pathway could be valuable tools for the treatment of inflammatory disorders and cancers.

NF-kappaB and Hsp70 are involved in the phospholipase Cgamma1 signaling pathway in colorectal cancer cells

The majority of deaths from colorectal cancer are due to tumor invasion and metastasis. Induced migration of tumor cell is generally considered to be one critical step in cancer progression to the invasive and metastatic stage. Phospholipase Cgamma1 (PLCgamma1) is a key molecular switch in the process. But, the mechanism and function of PLCgamma1 in colorectal cancer motility are unclear. We showed first in this report that epidermal growth factor (EGF) stimulated the phosphorylation of PLCgamma1 in human colorectal cancer cell line LoVo. Inhibition of PLCgamma1 with the pharmacologic agent U73122 decreased the migration of LoVo cells in a dose-dependent manner while EGF treatment reversed it partially. PLCgamma1 signaling pathway also upregulated the activity of NF-kappaB. Furthermore, expression of Hsp70 was increased by treatment with U73122 or pyrrolidine dithiocarbamate (PDTC), a NF-kappaB inhibitor. These data indicated that PLCgamma1 played a pivotal role in the migration of human colorectal cancer cell and first demonstrated that upregulation of NF-kappaB binding activity and downregulation of Hsp70 expression were PLCgamma1-dependent in LoVo cells.

Aberrant NF-kappaB2/p52 expression in Hodgkin/Reed-Sternberg cells and CD30-transformed rat fibroblasts

Overexpression of CD30 and constitutive nuclear factor-kappaB (NF-kappaB) activation are hallmarks of the malignant Hodgkin Reed-Sternberg (H-RS) cells. Previous investigations have demonstrated that both proliferation and survival of H-RS cells require constitutive NF-kappaB activity, which is comprised of the p50 and RelA subunits. We report here enhanced expression of NF-kappaB2/p52 and RelB-containing NF-kappaB DNA-binding activity in Epstein-Barr virus-negative H-RS cells. Kinetic studies revealed that a proteasome inhibitor MG132 induced p100 accumulation with reduced p52 expression in H-RS cells, suggesting proteasome-dependent processing of p100. In addition, treatment with a protein synthesis inhibitor cycloheximide rapidly downregulated inhibitor of NF-kappaB (IkappaB) kinase activity in H-RS cells. We also demonstrate that overexpression of CD30 in rat fibroblasts at levels comparable to those in H-RS cells results in constitutive IkappaB kinase activation, proteasome-dependent p100 processing, and NF-kappaB-dependent cell transformation. Our results thus indicate that CD30 triggers the noncanonical NF-kappaB activation pathway, and suggest that deregulated CD30 signaling contributes to the neoplastic features of H-RS cells.

Fish oil supplementation in the treatment of cachexia in pancreatic cancer patients

Patients with pancreatic cancer often experience a loss of weight and appetite, known as the anorexia-cachexia syndrome, which is associated with decreased quality of life and reduced survival. Research into the biological mechanisms of cachexia has demonstrated that an array of inflammatory mediators and tumor-derived factors cause appetite suppression, skeletal muscle proteolysis, and lipolysis,producing an overall hypercatabolic state that contributes to loss of fat and lean body mass. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been shown to modulate levels of proinflammatory cytokines, hepatic acute phase proteins, eicosanoids, and tumor-derived factors in animal models of cancer and may reverse some aspects of the process of cachexia. Results of clinical trials of n-3 PUFAs in the form of fish oils have been mixed, but should encourage further investigation into dietary fish oil supplementation, including the most effective route of administration and the proper dosage to promote optimal weight maintenance and to limit side effects. Concerns about standardization and quality control should also be considered. With the current available evidence, a recommendation for the use of omega 3 polyunsaturated fatty acids in pancreatic cancer cachexia is premature.

HTLV-I Tax induces a novel interaction between p65/RelA and p53 that results in inhibition of p53 transcriptional activity

Nuclear factor kappaB (NF-kappaB) activation plays a critical role in oncogenesis by human T-cell lymphotrophic virus type I (HTLV-I), the etiologic agent of adult T-cell leukemia (ATL), and is indispensable for maintenance of the malignant phenotype. In T lymphocytes, Tax-mediated p53 inhibition is dependent on Tax activation of the NF-kappaB pathway and is linked to p53 phosphorylation. We now report that blocking NF-kappaB transcriptional activation in HTLV-I-transformed cells restores p53 activity. Further, using mouse embryo fibroblast (MEF) null cells and antisense oligonucleotides to inhibit expression of NF-kappaB family members, we demonstrate that the p65 subunit of NF-kappaB is uniquely involved in p53 inhibition. Coimmunoprecipitation assays demonstrate an interaction between p65 and p53 in HTLV-I-transformed cells. In transient transfection assays, we demonstrate that Tax induces the p53-p65 interaction. Phosphorylation of p53 at serines 15 and 392 is critical for complex formation. Importantly, Tax-mediated p53 inhibition correlates with p65 and p53 interaction. By using chromatin immunoprecipitation (ChIP) assays, we find that in HTLV-I-transformed cells p53 and p65 form a complex on the inactive, p53-responsive murine double minute 2 (MDM2) promoter. Consistent with reduced transcriptional activity, transcription factor IID (TFIID) binding is not observed. These studies identify a unique mechanism for p53 regulation by the p65/RelA subunit of NF-kappaB.