Suppression of TNF-alpha-induced apoptosis by NF-kappaB

Cytokeratin-17 as a Potential Marker for Squamous Cell Carcinoma of the Larynx

To assess cytokeratin-17 (CK17) as an immunohistochemical marker for squamous cell carcinoma of the larynx, we stained 63 tissue samples from 63 consecutive patients who were believed or suspected to have squamous cell carcinoma of the larynx for CK17 and analyzed them by computerized histomorphometry. The mean staining intensity for CK17 was significantly stronger (p < .01) in cancerous cells, dysplasia, and normal epithelium proximal to the tumor than in distal normal epithelium and polyps. The percentage of stained area, within samples taken from a single patient, was significantly higher in malignancy and dysplasia as compared to distal normal epithelium and in malignancy as compared to dysplasia and proximal normal epithelium (p < .001). The integrated optical density was significantly higher in the malignant epithelium, dysplasia, polyps, and proximal normal epithelium than in distal normal epithelium (p < .0001). We conclude that CK17 is a highly sensitive and specific immunohistochemical marker for premalignant and malignant transformation in the larynx. Further investigation is warranted in order to assess the role of CK17 in determining safe resection borders.

Vascular-targeted TNFα and IFNγ inhibits orthotopic colorectal tumor growth

Background

Tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ) were originally identified to show potent anti-tumor activity and immunomodulatory capability. Unfortunately, several clinical studies of relevant cancer therapy did not observe significant response in maximum tolerated dose whether given alone or in combination. We have identified a tumor vasculature homing peptide (TCP-1 peptide) which targets only the vasculature of colorectal tumors but not normal blood vessels in animals and humans. In the current study, the antitumor effect of TCP-1/TNFα and TCP-1/IFNγ alone or in combination was studied in orthotopic colorectal tumor model.

Methods

TCP-1/TNFα and TCP-1/IFNγ recombinant proteins were prepared and i.v. injected to study the in vivo anticancer effect in orthotopic colorectal tumor model. Tumor apoptosis was determined by TUNEL staining and cleaved caspase-3 immunofluorescent staining. Tumor infiltrating lymphocytes were analyzed by immunofluorescent staining and flow cytometry. Western-blot was performed to examine the expression of proteins. Cell apoptosis was measured by Annexin V/PI flow cytometry.

Results

Targeted delivery of TNFα or IFNγ by TCP-1 peptide exhibited better antitumor activity than unconjugated format by inducing more tumor apoptosis and also enhancing antitumor immunity shown by increased infiltration of T lymphocytes inside the tumor. More importantly, combination therapy of TCP-1/TNFα and TCP-1/IFNγ synergistically suppressed tumor growth and alleviated systematic toxicity associated with untargeted therapy. This combination therapy induced massive apoptosis/secondary necrosis in the tumor.

Conclusions

Taken together, our data demonstrate TCP-1 is an efficient drug carrier for targeted therapy of colorectal cancer (CRC). TCP-1/TNFα combined with TCP-1/IFNγ is a promising combination therapy for CRC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0944-3) contains supplementary material, which is available to authorized users.

Cloaked in ubiquitin, a killer hides in plain sight: the molecular regulation of RIPK1

In the past decade, studies have shown how instrumental programmed cell death (PCD) can be in innate and adaptive immune responses. PCD can be a means to maintain homeostasis, prevent or promote microbial pathogenesis, and drive autoimmune disease and inflammation. The molecular machinery regulating these cell death programs has been examined in detail, although there is still much to be explored. A master regulator of programmed cell death and innate immunity is receptor-interacting protein kinase 1 (RIPK1), which has been implicated in orchestrating various pathologies via the induction of apoptosis, necroptosis, and nuclear factor-κB-driven inflammation. These and other roles for RIPK1 have been reviewed elsewhere. In a reflection of the ability of tumor necrosis factor (TNF) to induce either survival or death response, this molecule in the TNF pathway can transduce either a survival or a death signal. The intrinsic killing capacity of RIPK1 is usually kept in check by the chains of ubiquitin, enabling it to serve in a prosurvival capacity. In this review, the intricate regulatory mechanisms responsible for restraining RIPK1 from killing are discussed primarily in the context of the TNF signaling pathway and how, when these mechanisms are disrupted, RIPK1 is free to unveil its program of cellular demise.

The Tumor Suppressor Hace1 Is a Critical Regulator of TNFR1-Mediated Cell Fate

The HECT domain E3 ligase HACE1 has been identified as a tumor suppressor in multiple cancers. Here, we report that HACE1 is a central gatekeeper of TNFR1-induced cell fate. Genetic inactivation of HACE1 inhibits TNF-stimulated NF-κB activation and TNFR1-NF-κB-dependent pathogen clearance in vivo. Moreover, TNF-induced apoptosis was impaired in hace1 mutant cells and knockout mice in vivo. Mechanistically, HACE1 is essential for the ubiquitylation of the adaptor protein TRAF2 and formation of the apoptotic caspase-8 effector complex. Intriguingly, loss of HACE1 does not impair TNFR1-mediated necroptotic cell fate via RIP1 and RIP3 kinases. Loss of HACE1 predisposes animals to colonic inflammation and carcinogenesis in vivo, which is markedly alleviated by genetic inactivation of RIP3 kinase and TNFR1. Thus, HACE1 controls TNF-elicited cell fate decisions and exerts tumor suppressor and anti-inflammatory activities via a TNFR1-RIP3 kinase-necroptosis pathway.

•

Hace1 deficiency impairs TNF-driven NF-κB activation and apoptosis

•

Necroptosis via RIP1/RIP3/MLKL is still functional in the absence of Hace1

•

Hace1^–/– animals show enhanced severity of colitis and colon cancer

•

Genetic inactivation of RIP3 and TNFR1 reverts the phenotype of hace1^–/– mice

Tirofiban counteracts endothelial cell apoptosis through the VEGF/VEGFR2/pAkt axis

Tirofiban is used in the treatment of patients with acute coronary syndrome submitted to percutaneous coronary intervention (PCI). We have, previously, shown that tirofiban stimulates VEGF expression and promotes proliferation of endothelial cells. VEGF is a well known inhibitor of endothelial cell apoptosis. TNF-α is a pro-apoptotic cytokine released in the site of a vascular injury, including balloon angioplasty. We thought to investigate whether tirofiban was able to protect endothelial cells from cell death induced by TNF-α. For this study, we used human umbilical vein endothelial cells (HUVEC). Analysis of apoptosis was performed by propidium iodide incorporation, annexin V staining and measure of active caspase 3 levels. Western blot served for a semiquantitative measure of Akt activation, VEGF, and the pro-apoptotic Bim and Bak. Our results show that TNF-α was unable to activate caspase 3 and produce cell death in the presence of tirofiban. Activation of apoptosis was preceded by upregulation of Bim and Bak that resulted decreased after addition of tirofiban. The anti-apoptosis effect of tirofiban was reproduced by VEGF and counteracted by VEGFR2 blockade and the cation chelating agent ethylene glycol tetraacetic acid (EGTA). The use of p-Akt inhibitor, BEZ235,and Akt knockdown, suggested that pAkt mediated the prosurvival effect of tirofiban. In conclusion, tirofiban protects endothelial cells from apoptosis stimulated by TNF-α, due to its ability to stimulate VEGF production.

KHF16 is a Leading Structure from Cimicifuga foetida that Suppresses Breast Cancer Partially by Inhibiting the NF-κB Signaling Pathway

Triterpenoids extracted from Cimicifuga foetida have been reported to inhibit cancer by inducing cell cycle arrest and apoptosis. In this study, KHF16 (24-acetylisodahurinol-3-O-β-D-xylopyranoside), a cycloartane triterpenoid isolated from the rhizomes of C. foetida, showed potent anti-cancer activity in multiple ERα/PR/HER2 triple-negative breast cancer (TNBC) cell lines. KHF16 significantly induces cell cycle G2/M phase arrest and apoptosis in both MDA-MB-468 and SW527 TNBC cell lines. KHF16 reduces the expression levels of XIAP, Mcl-1, Survivin and Cyclin B1/D1 proteins. Importantly, KHF16 inhibits TNFα-induced IKKα/β phosphorylation, IKBα phosphorylation, p65 nuclear translocation and NF-κB downstream target gene expression, including XIAP, Mcl-1 and Survivin, in TNBC cells. These results suggest that KHF16 may inhibit TNBC by blocking the NF-κB signaling pathway in part.

Poly-ubiquitination in TNFR1-mediated necroptosis

Tumor necrosis factor (TNF) is a master pro-inflammatory cytokine, and inappropriate TNF signaling is implicated in the pathology of many inflammatory diseases. Ligation of TNF to its receptor TNFR1 induces the transient formation of a primary membrane-bound signaling complex, known as complex I, that drives expression of pro-survival genes. Defective complex I activation results in induction of cell death, in the form of apoptosis or necroptosis. This switch occurs via internalization of complex I components and assembly and activation of secondary cytoplasmic death complexes, respectively known as complex II and necrosome. In this review, we discuss the crucial regulatory functions of ubiquitination—a post-translational protein modification consisting of the covalent attachment of ubiquitin, and multiples thereof, to target proteins—to the various steps of TNFR1 signaling leading to necroptosis.

Roles of NF-κB in Cancer and Inflammatory Diseases and Their Therapeutic Approaches

Nuclear factor-κB (NF-κB) is a transcription factor that plays a crucial role in various biological processes, including immune response, inflammation, cell growth and survival, and development. NF-κB is critical for human health, and aberrant NF-κB activation contributes to development of various autoimmune, inflammatory and malignant disorders including rheumatoid arthritis, atherosclerosis, inflammatory bowel diseases, multiple sclerosis and malignant tumors. Thus, inhibiting NF-κB signaling has potential therapeutic applications in cancer and inflammatory diseases.

Cell shape and the microenvironment regulate nuclear translocation of NF-κB in breast epithelial and tumor cells

Although a great deal is known about the signaling events that promote nuclear translocation of NF-κB, how cellular biophysics and the microenvironment might regulate the dynamics of this pathway is poorly understood. In this study, we used high-content image analysis and Bayesian network modeling to ask whether cell shape and context features influence NF-κB activation using the inherent variability present in unperturbed populations of breast tumor and non-tumor cell lines. Cell–cell contact, cell and nuclear area, and protrusiveness all contributed to variability in NF-κB localization in the absence and presence of TNFα. Higher levels of nuclear NF-κB were associated with mesenchymal-like versus epithelial-like morphologies, and RhoA-ROCK-myosin II signaling was critical for mediating shape-based differences in NF-κB localization and oscillations. Thus, mechanical factors such as cell shape and the microenvironment can influence NF-κB signaling and may in part explain how different phenotypic outcomes can arise from the same chemical cues.

Titanium dioxide nanoparticles augment allergic airway inflammation and Socs3 expression via NF-κB pathway in murine model of asthma

Titanium dioxide nanoparticles (nTiO2) previously considered to possess relatively low toxicity both in vitro and in vivo, although classified as possibly carcinogenic to humans. Also, their adjuvant potential has been reported to promote allergic sensitization and modulate immune responses. Previously, in OVA induced mouse model of asthma we found high expression of Socs3 and low expression of Stat3 and IL-6. However, a clear understanding regarding the signaling pathways associated with nTiO2 adjuvant effect in mouse model of asthma is lacking. In the present study we investigated the status of Stat3/IL-6 and Socs3 and their relationship with NF-κB, with nTiO2 as an adjuvant in mouse model of asthma. nTiO2 when administered with ovalbumin (OVA) during sensitization phase augmented airway hyper-responsiveness (AHR), biochemical markers of lung damage and a mixed Th2/Th1 dependent immune response. At the same time, we observed significant elevation in the levels of Stat3, Socs3, NF-κB, IL-6 and TNF-α. Furthermore, transient in vivo blocking of NF-κB by NF-κB p65 siRNA, downregulated the expression of Socs3, IL-6 and TNF-α. Our study, thus, shows that nTiO2 exacerbate the inflammatory responses in lungs of pre-sensitized allergic individuals and that these changes are regulated via NF-κB pathway.

Study of pathway cross-talk interactions with NF-κB leading to its activation via ubiquitination or phosphorylation: A brief review

NFκB has been known to be a necessary transcription factor for the functioning of nearly all cells in a living organism. For its proper functioning, it talks to several other molecular cofactors and interacts with their functionalities resulting in a convoluted cross talking mesh of signalling networks. To completely understand the working of nuclear factor-kappa B protein, one needs to understand the interactions that occur during its lifecycle, with cofactors from various biological processes. This study attempts to elaborate and bridge the gaps on the cross-talk interactions that NFkB is a part of, during its activation pathway. For this Cytoscape and its various plugins (Cytocopter, Allegro, AgilentLitSearch and Styles) are employed. Other related pathways were also collated and analysed for cross-talk between NfκB and interacting molecules. NFκB was found to mainly interact with E3 ubiquitin ligase, NIK, RIP, TCR, IRAK-1, TLR, TRAF-6, NLR and IL-1, details of which are discussed as a part of this study.

Human MicroRNA miR-532-5p Exhibits Antiviral Activity against West Nile Virus via Suppression of Host Genes SESTD1 and TAB3 Required for Virus Replication

West Nile virus (WNV) is a mosquito-transmitted flavivirus that naturally circulates between mosquitos and birds but can also infect humans, causing severe neurological disease. The early host response to WNV infection in vertebrates primarily relies on the type I interferon pathway; however, recent studies suggest that microRNAs (miRNAs) may also play a notable role. In this study, we assessed the role of host miRNAs in response to WNV infection in human cells. We employed small RNA sequencing (RNA-seq) analysis to determine changes in the expression of host miRNAs in HEK293 cells infected with an Australian strain of WNV, Kunjin (WNVKUN), and identified a number of host miRNAs differentially expressed in response to infection. Three of these miRNAs were confirmed to be significantly upregulated in infected cells by quantitative reverse transcription (qRT)-PCR and Northern blot analyses, and one of them, miR-532-5p, exhibited a significant antiviral effect against WNVKUN infection. We have demonstrated that miR-532-5p targets and downregulates expression of the host genes SESTD1 and TAB3 in human cells. Small interfering RNA (siRNA) depletion studies showed that both SESTD1 and TAB3 were required for efficient WNVKUN replication. We also demonstrated upregulation of mir-532-5p expression and a corresponding decrease in the expression of its targets, SESTD1 and TAB3, in the brains of WNVKUN -infected mice. Our results show that upregulation of miR-532-5p and subsequent suppression of the SESTD1 and TAB3 genes represent a host antiviral response aimed at limiting WNVKUN infection and highlight the important role of miRNAs in controlling RNA virus infections in mammalian hosts.

IMPORTANCE

West Nile virus (WNV) is a significant viral pathogen that poses a considerable threat to human health across the globe. There is no specific treatment or licensed vaccine available for WNV, and deeper insight into how the virus interacts with the host is required to facilitate their development. In this study, we addressed the role of host microRNAs (miRNAs) in antiviral response to WNV in human cells. We identified miR-532-5p as a novel antiviral miRNA and showed that it is upregulated in response to WNV infection and suppresses the expression of the host genes TAB3 and SESTD1 required for WNV replication. Our results show that upregulation of miR-532-5p and subsequent suppression of the SESTD1 and TAB3 genes represent an antiviral response aimed at limiting WNV infection and highlight the important role of miRNAs in controlling virus infections in mammalian hosts.

The Type I IFN-Induced miRNA, miR-21

The interferon (IFN) family of cytokines not only has antiviral properties at various steps in the viral replication cycle, but also anticancer activity through multiple pathways that include inhibiting cell proliferation, regulating cellular responses to inducers of apoptosis and modulating angiogenesis and the immune system. IFNs are known to induce their biological activity through the induction of protein encoding IFN-stimulated genes. However, recent studies have established that IFNs also induce the expression of microRNAs (miRNAs), which are small endogenous non-coding RNAs that suppress gene expression at the post-transcriptional level. MiRNAs play critical roles in tumorigenesis and have been implicated to act as either oncogenes or tumor suppressors in various human cancers. Therefore, IFN-induced miRNAs play an important role, not only in the host response to innate immune response to cancer, but also in the tumorigenic process itself. Furthermore, IFN-induced miRNAs may participate in and/or orchestrate antiviral defense in certain viral infections. In this review, we describe our recent studies on the induction of miR-21 by type I IFN, the role of the STAT3 and NFκB signaling pathways in IFN-induced miR-21 expression, the role of miR-21 in different cancers and the role of miR-21 in regulating the antiviral response.

Rap1 GTPase Inhibits Tumor Necrosis Factor-α-Induced Choroidal Endothelial Migration via NADPH Oxidase- and NF-κB-Dependent Activation of Rac1

Macrophage-derived tumor necrosis factor (TNF)-α has been found in choroidal neovascularization (CNV) surgically removed from patients with age-related macular degeneration. However, the role of TNF-α in CNV development remains unclear. In a murine laser-induced CNV model, compared with un-lasered controls, TNF-α mRNA was increased in retinal pigment epithelial and choroidal tissue, and TNF-α colocalized with lectin-stained migrating choroidal endothelial cells (CECs). Inhibition of TNF-α with a neutralizing antibody reduced CNV volume and reactive oxygen species (ROS) level around CNV. In CECs, pretreatment with the antioxidant apocynin or knockdown of p22phox, a subunit of NADPH oxidase, inhibited TNF-α-induced ROS generation. Apocynin reduced TNF-α-induced NF-κB and Rac1 activation, and inhibited TNF-α-induced CEC migration. TNF-α-induced Rac1 activation and CEC migration were inhibited by NF-κB inhibitor Bay11-7082. Overexpression of Rap1a prevented TNF-α-induced ROS generation and reduced NF-κB and Rac1 activation. Activation of Rap1 by 8-(4-chlorophenylthio)adenosine-2'-O-Me-cAMP prevented TNF-α-induced CEC migration and reduced laser-induced CNV volume, ROS generation, and activation of NF-κB and Rac1. These findings provide evidence that active Rap1a inhibits TNF-α-induced CEC migration by inhibiting NADPH oxidase-dependent NF-κB and Rac1 activation and suggests that Rap1a de-escalates CNV development by interfering with ROS-dependent signaling in several steps of the pathogenic process.

Myocardial NF-κB activation is essential for zebrafish heart regeneration

Heart regeneration offers a novel therapeutic strategy for heart failure. Unlike mammals, lower vertebrates such as zebrafish mount a strong regenerative response following cardiac injury. Heart regeneration in zebrafish occurs by cardiomyocyte proliferation and reactivation of a cardiac developmental program, as evidenced by induction of gata4 regulatory sequences in regenerating cardiomyocytes. Although many of the cellular determinants of heart regeneration have been elucidated, how injury triggers a regenerative program through dedifferentiation and epicardial activation is a critical outstanding question. Here, we show that NF-κB signaling is induced in cardiomyocytes following injury. Myocardial inhibition of NF-κB activity blocks heart regeneration with pleiotropic effects, decreasing both cardiomyocyte proliferation and epicardial responses. Activation of gata4 regulatory sequences is also prevented by NF-κB signaling antagonism, suggesting an underlying defect in cardiomyocyte dedifferentiation. Our results implicate NF-κB signaling as a key node between cardiac injury and tissue regeneration.

Simultaneous detection of mRNA and protein in single cells using immunofluorescence-combined single-molecule RNA FISH

Although the concept of combining immunofluorescence (IF) with single-molecule RNA fluorescence in situ hybridization (smRNA FISH) seems obvious, the specific materials used during IF and smRNA FISH make it difficult to perform these procedures simultaneously on the same specimen. Even though there are reports where IF and smRNA FISH were combined with success, these were insufficient in terms of signal intensities, staining patterns, and GFP-compatibility, and a detailed exploration of the various factors that influence IF and smRNA FISH outcome has not been published yet. Here, we report a detailed study of conditions and reagents used in classic IF and smRNA FISH that allowed us to establish an easy, robust, and GFP-compatible procedure. Our protocol enables simultaneous detection of mRNA and protein quantity as well as the subcellular distribution of these molecules in single cells by combining an RNase-free modification of the IF technique and the more recent smRNA FISH method. Using this procedure, we have shown the direct interaction of RNase MCPIP1 with IL-6 mRNA. We also demonstrate the use of our protocol in heterogeneous cell population analysis, revealing cell-to-cell differences in mRNA and protein content.

Galectin 3 regulates HCC cell invasion by RhoA and MLCK activation

Hepatocellular carcinoma (HCC) carries a poor prognosis with no effective treatment available other than liver transplantation for selected patients. Vascular invasion of HCC is one of the most important negative predictor of survival. As the regulation of invasion of HCC cells is not well understood, our aim was to study the mechanisms by which galectin 3, a β-galactosidase-binding lectin mediates HCC cell migration. HCC was induced by N-diethylnitrosamine in wild-type and galectin 3(-/-) mice, and tumor formation, histology, and tumor cell invasion were assessed. The galectin 3(-/-) mice developed significantly smaller tumor burden with a less invasive phenotype than the wild-type animals. Galectin 3 was upregulated in the wild-type HCC tumor tissue, but not in the surrounding parenchyma. Galectin 3 expression in HCC was induced by NF-κB transactivation as determined by chromatin immunoprecipitation assays. In vitro studies assessed the pro-migratory effects of galectin 3. The migration of hepatoma cells was significantly decreased after transfection by the galectin 3 siRNA and also after using the Rho kinase inhibitor Y-27632. The reorganization of the actin cytoskeleton, RhoA GTPase activity and the phosphorylation of MLC2 (myosin light chain 2) were decreased in the galectin 3 siRNA-transfected cells. In addition, in vitro and in vivo evidence showed that galectin 3 deficiency reduced hepatoma cell proliferation and increased their apoptosis rate. In conclusion, galectin 3 is an important lectin that is induced in HCC cells, and promotes hepatoma cell motility and invasion by an autocrine pathway. Targeting galectin 3 therefore could be an important novel treatment strategy to halt disease progression.

H. pylori-Induced DNA Strand Breaks Are Introduced by Nucleotide Excision Repair Endonucleases and Promote NF-κB Target Gene Expression

The human bacterial pathogen Helicobacter pylori exhibits genotoxic properties that promote gastric carcinogenesis. H. pylori introduces DNA double strand breaks (DSBs) in epithelial cells that trigger host cell DNA repair efforts. Here, we show that H. pylori-induced DSBs are repaired via error-prone, potentially mutagenic non-homologous end-joining. A genome-wide screen for factors contributing to DSB induction revealed a critical role for the H. pylori type IV secretion system (T4SS). Inhibition of transcription, as well as NF-κB/RelA-specific RNAi, abrogates DSB formation. DSB induction further requires β1-integrin signaling. DSBs are introduced by the nucleotide excision repair endonucleases XPF and XPG, which, together with RelA, are recruited to chromatin in a highly coordinated, T4SS-dependent manner. Interestingly, XPF/XPG-mediated DNA DSBs promote NF-κB target gene transactivation and host cell survival. In summary, H. pylori induces XPF/XPG-mediated DNA damage through activation of the T4SS/β1-integrin signaling axis, which promotes NF-κB target gene expression and host cell survival.

Experimental study of the protective effects of SYVN1 against diabetic retinopathy

Genetic factors play an important role in the pathogenesis of diabetic retinopathy (DR). While many studies have focused on genes that increase susceptibility to DR, herein, we aimed to explore genes that confer DR resistance. Previously, we identified Hmg CoA reductase degradation protein 1 (SYVN1) as a putative DR protective gene via gene expression analysis. Transgenic mice overexpressing SYVN1 and wild-type (WT) mice with streptozotocin-induced diabetes were used in this experiment. Retinal damage and vascular leakage were investigated 6 months after induction of diabetes by histopathological and retinal cell apoptosis analyses and by retinal perfusion of fluorescein isothiocyanate-conjugated dextran. Compared with diabetic WT mice, diabetic SYVN1 mice had significantly more cells and reduced apoptosis in the retinal ganglion layer. Retinal vascular leakage was significantly lower in diabetic SYVN1 mice than in diabetic WT mice. The expression levels of endoplasmic reticulum (ER) stress-related, pro-inflammatory, and pro-angiogenic genes were also analyzed. Lower expression levels were observed in diabetic SYVN1 mice than in WT controls, suggesting that SYVN1 may play an important role in inhibiting ER stress, chronic inflammation, and vascular overgrowth associated with DR. Thus, these results strongly supported our hypothesis that SYVN1 confers DR resistance.

Therapeutic applications of TRAIL receptor agonists in cancer and beyond

TRAIL/Apo-2L is a member of the TNF superfamily first described as an apoptosis-inducing cytokine in 1995. Similar to TNF and Fas ligand, TRAIL induces apoptosis in caspase-dependent manner following TRAIL death receptor trimerization. Because tumor cells were shown to be particularly sensitive to this cytokine while normal cells/tissues proved to be resistant along with being able to synthesize and release TRAIL, it was rapidly appreciated that TRAIL likely served as one of our major physiologic weapons against cancer. In line with this, a number of research laboratories and pharmaceutical companies have attempted to exploit the ability of TRAIL to kill cancer cells by developing recombinant forms of TRAIL or TRAIL receptor agonists (e.g., receptor-specific mAb) for therapeutic purposes. In this review article we will describe the biochemical pathways used by TRAIL to induce different cell death programs. We will also summarize the clinical trials related to this pathway and discuss possible novel uses of TRAIL-related therapies. In recent years, the physiological importance of TRAIL has expanded beyond being a tumoricidal molecule to one critical for a number of clinical settings - ranging from infectious disease and autoimmunity to cardiovascular anomalies. We will also highlight some of these conditions where modulation of the TRAIL/TRAIL receptor system may be targeted in the future.

NF-κB-Independent Role of IKKα/IKKβ in Preventing RIPK1 Kinase-Dependent Apoptotic and Necroptotic Cell Death during TNF Signaling

TNF is a master pro-inflammatory cytokine. Activation of TNFR1 by TNF can result in both RIPK1-independent apoptosis and RIPK1 kinase-dependent apoptosis or necroptosis. These cell death outcomes are regulated by two distinct checkpoints during TNFR1 signaling. TNF-mediated NF-κB-dependent induction of pro-survival or anti-apoptotic molecules is a well-known late checkpoint in the pathway, protecting cells from RIPK1-independent death. On the other hand, the molecular mechanism regulating the contribution of RIPK1 to cell death is far less understood. We demonstrate here that the IKK complex phosphorylates RIPK1 at TNFR1 complex I and protects cells from RIPK1 kinase-dependent death, independent of its function in NF-κB activation. We provide in vitro and in vivo evidence that inhibition of IKKα/IKKβ or its upstream activators sensitizes cells to death by inducing RIPK1 kinase-dependent apoptosis or necroptosis. We therefore report on an unexpected, NF-κB-independent role for the IKK complex in protecting cells from RIPK1-dependent death downstream of TNFR1.

p53 modulates NF-κB mediated epithelial-to-mesenchymal transition in head and neck squamous cell carcinoma

OBJECTIVES

To investigate the role of p53 in NF-κB mediated epithelial-to-mesenchymal (EMT) in head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

We utilized HNSCC and normal oral epithelial cell lines as our model system. We used a lentiviral shRNA system to silence the expression of p65 and p53 in these cell lines. Mutant and wild-type (WT) p53 background genotypes were analyzed. The expression of epithelial and mesenchymal markers was determined using western blotting and quantitative PCR assays. Cell morphology, growth, and invasion were determined using a 3-dimensional spheroid culture and anchorage independent growth (AIG) assays.

RESULTS

In HNSCC cells with mutant p53 we found that silencing p65 expression promoted EMT. In contrast, in the context of WT p53, ectopic p65 over-expression promoted EMT. Ablation of WT p53 in normal oral epithelial cells blocked EMT induced by p65 over-expression. We demonstrate that AIG and apoptosis induced by NF-κB activation is regulated by p53.

CONCLUSION

Our data demonstrates that p53 mutational status is critical in determining the outcome of NF-κB activation in HNSCC. In the presence of WT p53, excess p65 signal can promote EMT. Conversely, ablation of p65 in the context of mutant p53 drives EMT. These results demonstrate that p53 mutational status alters the outcome of NF-κB signaling. These results, though preliminary, demonstrate the critical role of p53 mutational status in determining the outcome of NF-κB signaling and suggest that monitoring p53 status may inform the utility of NF-κB inhibitor treatment in HNSCC.

Regulation of tumour necrosis factor signalling: live or let die

Tumour necrosis factor (TNF) is a pro-inflammatory cytokine that has important roles in mammalian immunity and cellular homeostasis. Deregulation of TNF receptor (TNFR) signalling is associated with many inflammatory disorders, including various types of arthritis and inflammatory bowel disease, and targeting TNF has been an effective therapeutic strategy in these diseases. This Review focuses on the recent advances that have been made in understanding TNFR signalling and the consequences of its deregulation for cellular survival, apoptosis and regulated necrosis. We discuss how TNF-induced survival signals are distinguished from those that lead to cell death. Finally, we provide a brief overview of the role of TNF in inflammatory and autoimmune diseases, and we discuss up-to-date and future treatment strategies for these disorders.

The Role of miR-21 in Cancer

MicroRNAs (miRNAs) are small endogenous noncoding RNAs that suppress gene expression at the post-transcriptional level. In the past decade, miRNAs have been extensively studied in a number of different human cancers. MiRNAs have been identified to act both as oncogenes and as tumor suppressors. In addition, miRNAs are associated with the intrinsic resistance of cancer to various forms of therapy, and they are implicated in both tumor progression and metastasis. The characterization of the specific alterations in the patterns of miRNA expression in cancer has great potential for identifying biomarkers for early cancer detection, as well as for potential therapeutic intervention in cancer treatment. In this chapter, we describe the ever-expanding role of miR-21 and its target genes in different cancers, and provide insight into how this oncogenic miRNA regulates cancer cell proliferation, migration, and apoptosis by suppressing the expression of tumor suppressors.

Induction of apoptotic cell death by betulin in multidrug-resistant human renal carcinoma cells

Betulin, a triterpene from the bark of various species of birch tree, has various biological effects, including antiviral, antifungal and anticancer activities. The aim of the present study was to elucidate the mechanisms underlying the apoptotic effect of betulin in RCC4 multidrug-resistant human renal carcinoma cells. To evaluate anticancer activity, we performed cell viability and caspase activity assays, a proteome profiler array and western blot analysis in RCC4 cells. Betulin significantly decreased RCC4 cell viability in a time- and concentration-dependent manner. Betulin activated caspase family proteins, including caspase-3, -7, -8 and -9, and increased the expression of apoptosis-related proteins, including PARP and Bcl-2 family members. In an apoptosis array, betulin activated the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors TRAIL R1/DR4 and R2/DR5, and tumour necrosis factor receptor 1 (TNFR1), suggesting that betulin treatment leads to induction of apoptosis through both intrinsic and extrinsic apoptosis pathways in RCC4 cells. Notably, betulin significantly enhanced cytotoxicity and PARP cleavage in etoposide-treated RCC4 cells, and downregulated the expression of multidrug resistance protein 1 (MDR1). Taken together, our findings suggest that the anticancer effects of betulin involve induction of apoptosis and sensitisation of RCC4 cells, providing potentially useful information applicable to the use of betulin in renal cancer treatment.

Hepatitis C virus NS5A drives a PTEN-PI3K/Akt feedback loop to support cell survival

BACKGROUND & AIMS

Decreased levels of phosphatase and tensin homologue (PTEN) are associated with hepatocellular carcinoma (HCC) pathogenesis and poor prognosis in hepatitis C virus (HCV)-infected HCC patients. The molecular processes governing the reduction in PTEN and outcome of PTEN dysfunction in hepatocytes are poorly understood.

METHODS

The levels of proteins and mRNA were assessed by real time PCR and immunoblot. PTEN promoter activity was measured by reporter assay. Signalling pathways were perturbed using siRNAs or pharmacological inhibitors.

RESULTS

Here, we report that HCV down-regulates PTEN expression at the transcriptional level by decreasing its promoter activity, mRNA transcription, and protein levels. We further identify NS5A protein as a key determinant of PTEN reduction among HCV proteins. NS5A-mediated down-regulation of PTEN occurs through a cooperation of reactive oxygen species (ROS)-dependent Nuclear Factor- kappa B (NF-κB) and ROS-independent phosphoinositol-3-kinase (PI3K) pathways. Moreover, NS5A protects cells against apoptosis. In addition, we found that down-regulation of PTEN relieves its inhibitory effect on PI3K-Akt pathway and triggers cumulative activation of Akt. This PTEN-PI3K/Akt feedback network mediates the suppression of cell apoptosis caused by NS5A.

CONCLUSIONS

These data demonstrate that HCV NS5A down-regulates PTEN expression through a cooperation of ROS-dependent and -independent pathways that subsequently drives a PTEN-PI3K/Akt feedback loop to support cell survival. Our findings provide new insights suggesting that NS5A contributes to HCV-related hepatocarcinogenesis.

Environmental immune disruptors, inflammation and cancer risk

An emerging area in environmental toxicology is the role that chemicals and chemical mixtures have on the cells of the human immune system. This is an important area of research that has been most widely pursued in relation to autoimmune diseases and allergy/asthma as opposed to cancer causation. This is despite the well-recognized role that innate and adaptive immunity play as essential factors in tumorigenesis. Here, we review the role that the innate immune cells of inflammatory responses play in tumorigenesis. Focus is placed on the molecules and pathways that have been mechanistically linked with tumor-associated inflammation. Within the context of chemically induced disturbances in immune function as co-factors in carcinogenesis, the evidence linking environmental toxicant exposures with perturbation in the balance between pro- and anti-inflammatory responses is reviewed. Reported effects of bisphenol A, atrazine, phthalates and other common toxicants on molecular and cellular targets involved in tumor-associated inflammation (e.g. cyclooxygenase/prostaglandin E2, nuclear factor kappa B, nitric oxide synthesis, cytokines and chemokines) are presented as example chemically mediated target molecule perturbations relevant to cancer. Commentary on areas of additional research including the need for innovation and integration of systems biology approaches to the study of environmental exposures and cancer causation are presented.

Parthenolide induces apoptosis in colitis-associated colon cancer, inhibiting NF-κB signaling

Recently, the nuclear factor (NF)-κB inhibitor parthenolide (PT) was identified as a promising anticancer agent for the promotion of cancer cell apoptosis. Additionally, our previous study demonstrated that PT administration suppresses tumor growth in a xenograft model of colorectal cancer cells via regulation of the B-cell lymphoma-2 (Bcl-2) family. However, the role of PT in the development of colitis-associated colon cancer (CAC) is poorly understood. Therefore, the aim of the present study was to investigate the effects of PT administration on CAC using a murine model. Azoxymethane (AOM) and dextran sulfate sodium (DSS) were administered to induce experimental CAC in the following three groups of treated mice: i) AOM and DSS plus vehicle; ii) AOM, DSS and 2 mg/kg PT; and iii) AOM, DSS and 4 mg/kg PT. It was demonstrated that the histological acuteness of AOM/DSS-induced CAC was significantly reduced following the administration of PT, resulting in decreased NF-κB p65 expression levels via a blockade of phosphorylation and subsequent degradation of inhibitor of κB-α (IκBα). Furthermore, PT administration appeared to enhance the process of carcinogenesis via the downregulation of the antiapoptotic proteins Bcl-2 and Bcl-extra large, mediated by inhibition of NF-κB activation. Apoptosis and caspase-3 expression were markedly increased in the PT-treated group. These findings indicate that PT inhibits IκBα phosphorylation and NF-κB activation, resulting in the initiation of apoptosis and the eventual suppression of CAC development. The beneficial effects of PT treatment observed in the experimental CAC model indicate the potential chemopreventive and therapeutic role of PT in CAC.

Vitamin D attenuates pro-inflammatory TNF-α cytokine expression by inhibiting NF-кB/p65 signaling in hypertrophied rat hearts

A growing body of evidence suggests that immune activation and inflammatory mediators may play a key role in the development and progression of left ventricle (LV) hypertrophy. The present study was designed to test the hypothesis that the cardioprotective effect of cholecalciferol (Vit-D3) is mediated via the regulation of messenger RNA (mRNA) expression of pro-inflammatory cytokines. Rats were randomly divided into four groups: control group received normal saline (0.9 % NaCl) i.p. for 14 days; Vit-D3 group received Vit-D3 at a dose of 12 μg/kg/day by gavage for 14 days; ISO group received saline for 7 days, and at day 7, ISO (5 mg/kg/day) was injected i.p. for 7 consecutive days to induce cardiac hypertrophy; and Vit-D3 + ISO group was treated with Vit-D3 for 14 days, and at day 7, ISO was administered for 7 consecutive days. Heart/body weight ratio, troponin-T, creatine kinase-MB, and tumor necrosis factor-α (TNF-α) levels of LV tissue were estimated. Levels of mRNA expression of NF-кB (NF-кB)/p65 and inhibitory kappa B (IкB)-α were determined by real-time PCR. Vit-D3 administration before and during induction of cardiac hypertrophy significantly reduced (P < 0.001) cardiac biomarkers. The histopathological examination further confirmed these results. In addition, Vit-D3 significantly decreased (P < 0.001) NF-кB-p65 mRNA expression and increased (P < 0.01) IкB-α mRNA expression in LV tissues compared to ISO group. Based on these findings, it was concluded that the administration of cholecalciferol markedly attenuated the development of ISO-induced cardiac hypertrophy likely through downregulation of TNF-α /NF-кb/p65 signaling pathways. However, it should be pointed out that other signaling pathways may contribute to the cardioprotective effect of Vit-D3 which requires further investigation.

Tumor necrosis factor, tumor necrosis factor inhibition, and cancer risk

OBJECTIVE

Tumor necrosis factor (TNF) is a highly pleiotropic cytokine with multiple activities other than its originally discovered role of tumor necrosis in rodents. TNF is now understood to play a contextual role in driving either tumor elimination or promotion. Using both animal and human data, this review examines the role of TNF in cancer development and the effect of TNF and TNF inhibitors (TNFis) on malignancy risk.

RESEARCH DESIGN

A literature review was performed using relevant search terms for TNF and malignancy.

RESULTS

Although administration of TNF can cause tumor regression in specific rodent tumor models, human expression polymorphisms suggest that TNF can be a tumor-promoting cytokine, whereas blocking the TNF pathway in a variety of tumor models inhibits tumor growth. In addition to direct effects of TNF on tumors, TNF can variously affect immunity and the tumor microenvironment. Whereas TNF can promote immune surveillance designed to eliminate tumors, it can also drive chronic inflammation, autoimmunity, angiogenesis, and other processes that promote tumor initiation, growth, and spread. Key players in TNF signaling that shape this response include NF-κB and JNK, and malignant-inflammatory cell interactions, each of which may have different responses to TNF signaling. Focusing on rheumatoid arthritis (RA) patients, where clinical experience is most extensive, a review of the clinical literature shows no increased risk of overall malignancy or solid tumors such as breast and lung cancers with exposure to TNFis. Lymphoma rates are not increased with use of TNFis. Conflicting data exist regarding the risks of melanoma and nonmelanoma skin cancer. Data regarding the risk of recurrent malignancy are limited.

CONCLUSIONS

Overall, the available data indicate that elevated TNF is a risk factor for cancer, whereas its inhibition in RA patients is not generally associated with an increased cancer risk. In particular, TNF inhibition is not associated with cancers linked to immune suppression. A better understanding of the tumor microenvironment, molecular events underlying specific tumors, and epidemiologic studies of malignancies within specific disease indications should enable more focused pharmacovigilance studies and a better understanding of the potential risks of TNFis.

Fenofibrate in cancer: mechanisms involved in anticancer activity

Objective: To review the mechanisms of anti-cancer activity of fenofibrate (FF) and other Peroxisome Proliferator Activator Receptor α (PPARα) agonists based on evidences reported in the published literature.Methods: We extensively reviewed the literature concerning FF as an off target anti-cancer drug. Controversies regarding conflicting findings were also addressed.Results: The main mechanism involved in anti-cancer activity is anti-angiogenesis through down-regulation of  Vascular Endothelial Growth Factor (VEGF), Vascular Endothelial Growth Factor Receptor (VEGFR) and Hypoxia Inducible factor-1 α (HIF-1α), inhibition of endothelial cell migration, up-regulation of endostatin and thrombospondin-1, but there are many other contributing mechanisms like apoptosis and cell cycle arrest, down-regulation of Nuclear Factor Kappa B (NF-kB) and Protein kinase B (Akt) and decrease of cellular energy by impairing mitochondrial function. Growth impairment is related to down-regulation of Phospho-Inositol 3 Kinase (PI3K)/Akt axis and down-regulation of the p38 map kinase (MAPK) cascade. A possible role should be assigned to FF stimulated over-expression of Tribbles Homolog-3 (TRIB3) which inhibits Akt phosphorylation. Important anti-cancer and anti-metastatic activities are due to down-regulation of MCP-1 (monocyte chemotactic protein-1), decreased Metalloprotease-9 (MMP-9) production, weak down-regulation of adhesion molecules like E selectin, intercellular adhesion molecules (ICAM) and Vascular Endothelial Adhesion Molecules (VCAM), and decreased secretion of chemokines like Interleukin-6 (IL-6), and down-regulation of cyclin D-1. There is no direct link between FF activity in lipid metabolism and anticancer activity, except for the fact that many anticancer actions are dependent from PPARα agonism. FF exhibits also PPARα independent anti-cancer activities.Conclusions: There are strong evidences indicating that FF can disrupt growth-related activities in many different cancers, due to anti-angiogenesis and anti-inflammatory effects. Therefore FF may be useful as a complementary adjunct treatment of cancer, particularly included in anti-angiogenic protocols like those currently increasingly used in glioblastoma. There are sound reasons to initiate well planned phase II clinical trials for FF as a complementary adjunct treatment of cancer.

Necroptosis: Pathway diversity and characteristics

Regulated cell death is a physiological process that controls organismal homeostasis. Deregulation of cell death can lead to the development of a number of human diseases and tissue damage. Apoptosis is a best-known model of caspase-dependent regulated cell death, but recently necroptosis has garnered a lot of attention as a form of regulated cell death not mediated by caspases. Different stimuli can trigger necroptosis, and all of them converge at the activation of the protein kinase RIP3 (receptor-interacting protein 3) and the pseudokinase MLKL (mixed lineage kinase domain-like). Necroptosis activation relies on the unique protein-interaction motif RHIM (RIP homology interaction motif). Different RHIM-containing proteins (RIP1, DAI and TRIF) transduce necroptotic signals from the cell death trigger to the cell death mediators RIP3-MLKL. RIP1 has a particularly important and complex role in necroptotic cell death regulation ranging from cell death activation to inhibition, often in a cell type and context dependent fashion.

Amyloid-β reduces the expression of neuronal FAIM-L, thereby shifting the inflammatory response mediated by TNFα from neuronal protection to death

The brains of patients with Alzheimer's disease (AD) present elevated levels of tumor necrosis factor-α (TNFα), a cytokine that has a dual function in neuronal cells. On one hand, TNFα can activate neuronal apoptosis, and on the other hand, it can protect these cells against amyloid-β (Aβ) toxicity. Given the dual behavior of this molecule, there is some controversy regarding its contribution to the pathogenesis of AD. Here we examined the relevance of the long form of Fas apoptotic inhibitory molecule (FAIM) protein, FAIM-L, in regulating the dual function of TNFα. We detected that FAIM-L was reduced in the hippocampi of patients with AD. We also observed that the entorhinal and hippocampal cortex of a mouse model of AD (PS1_M146LxAPP_751sl) showed a reduction in this protein before the onset of neurodegeneration. Notably, cultured neurons treated with the cortical soluble fractions of these animals showed a decrease in endogenous FAIM-L, an effect that is mimicked by the treatment with Aβ-derived diffusible ligands (ADDLs). The reduction in the expression of FAIM-L is associated with the progression of the neurodegeneration by changing the inflammatory response mediated by TNFα in neurons. In this sense, we also demonstrate that the protection afforded by TNFα against Aβ toxicity ceases when endogenous FAIM-L is reduced by short hairpin RNA (shRNA) or by treatment with ADDLs. All together, these results support the notion that levels of FAIM-L contribute to determine the protective or deleterious effect of TNFα in neuronal cells.

Fas and TRAIL 'death receptors' as initiators of inflammation: Implications for cancer

Fas (CD95/APO-1) and TRAIL (CD253, TNFSF10, APO2) are members of a subset of the TNF receptor superfamily known as 'death receptors'. To date, the overwhelming majority of studies on Fas and TRAIL (TNF-related apoptosis-inducing ligand) have explored the role of these receptors as initiators of apoptosis. However, sporadic reports also suggest that engagement of the Fas and TRAIL receptors can lead to other outcomes such as cytokine and chemokine production, cell proliferation, cell migration and differentiation. Indeed, although transformed cells frequently express Fas and TRAIL, most do not undergo apoptosis upon engagement of these receptors and significant effort has been devoted toward exploring how to sensitize such cells to the pro-apoptotic effects of 'death receptor' stimulation. Moreover, the expression of Fas and TRAIL receptors is greatly elevated in many cancer types such as hepatocellular carcinoma, renal carcinoma and ovarian cancer, suggesting that such tumors benefit from the expression of these receptors. Furthermore, several studies have shown that tumor proliferation, progression and invasion can be impaired through blocking or downregulation of Fas expression, but the mechanistic basis for these effects is largely unknown. Thus, the characterization of Fas and TRAIL as 'death receptors' is a gross oversimplification, especially in the context of cancer. It is becoming increasingly clear that 'death receptor' engagement can lead to outcomes, other than apoptosis, that become subverted by certain tumors to their benefit. Here we will discuss death-independent outcomes of Fas and TRAIL signaling and their implications for cancer.

Fine-tuning of NFκB by glycogen synthase kinase 3β directs the fate of glomerular podocytes upon injury

NFκB is regulated by a myriad of signaling cascades including glycogen synthase kinase (GSK) 3β and plays a Janus role in podocyte injury. In vitro, lipopolysaccharide or adriamycin elicited podocyte injury and cytoskeletal disruption, associated with NFκB activation and induced expression of NFκB target molecules, including pro-survival Bcl-xL and podocytopathic mediators like MCP-1, cathepsin L and B7-1. Broad range inhibition of NFκB diminished the expression of all NFκB target genes, restored cytoskeleton integrity, but potentiated apoptosis. In contrast, blockade of GSK3β by lithium or TDZD-8, mitigated the expression of podocytopathic mediators, ameliorated podocyte injury, but barely affected Bcl-xL expression or sensitized apoptosis. Mechanistically, GSK3β was sufficient and essential for RelA/p65 phosphorylation specifically at serine 467, which specifies the expression of selective NFκB target molecules, including podocytopathic mediators, but not Bcl-xL. In vivo, lithium or TDZD-8 therapy improved podocyte injury and proteinuria in mice treated with lipopolysaccharide or adriamycin, concomitant with suppression of podocytopathic mediators but retained Bcl-xL in glomerulus. Broad range inhibition of NFκB conferred similar but much weakened antiproteinuric and podoprotective effects accompanied with a blunted glomerular expression of Bcl-xL and marked podocyte apoptosis. Thus, the GSK3β dictated fine-tuning of NFκB may serve as a novel therapeutic target for podocytopathy.

Necroptosis suppresses inflammation via termination of TNF- or LPS-induced cytokine and chemokine production

TNF promotes a regulated form of necrosis, called necroptosis, upon inhibition of caspase activity in cells expressing RIPK3. Because necrosis is generally more pro-inflammatory than apoptosis, it is widely presumed that TNF-induced necroptosis may be detrimental in vivo due to excessive inflammation. However, because TNF is intrinsically highly pro-inflammatory, due to its ability to trigger the production of multiple cytokines and chemokines, rapid cell death via necroptosis may blunt rather than enhance TNF-induced inflammation. Here we show that TNF-induced necroptosis potently suppressed the production of multiple TNF-induced pro-inflammatory factors due to RIPK3-dependent cell death. Similarly, necroptosis also suppressed LPS-induced pro-inflammatory cytokine production. Consistent with these observations, supernatants from TNF-stimulated cells were more pro-inflammatory than those from TNF-induced necroptotic cells in vivo. Thus necroptosis attenuates TNF- and LPS-driven inflammation, which may benefit intracellular pathogens that evoke this mode of cell death by suppressing host immune responses.

Ophiobolin O isolated from Aspergillus ustus induces G1 arrest of MCF-7 cells through interaction with AKT/GSK3β/cyclin D1 signaling

Ophiobolin O is a member of ophiobolin family, which has been proved to be a potent anti-tumor drug candidate for human breast cancer. However, the anti-tumor effect and the mechanism of ophiobolin O remain unclear. In this study, we further verified ophiobolin O-induced G1 phase arrest in human breast cancer MCF-7 cells, and found that ophiobolin O reduced the phosphorylation level of AKT and GSK3β, and induced down-regulation of cyclin D1. The inverse docking (INVDOCK) analysis indicated that ophiobolin O could bind to GSK3β, and GSK3β knockdown abolished cyclin D1 degradation and G1 phase arrest. Pre-treatment with phosphatase inhibitor sodium or thovanadate halted dephosphorylation of AKT and GSK3β, and blocked ophiobolin O-induced G1 phase arrest. These data suggest that ophiobolin O may induce G1 arrest in MCF-7 cells through interaction with AKT/GSK3β/cyclin D1 signaling. In vivo, ophiobolin O suppressed tumor growth and showed little toxicity in mouse xenograft models. Overall, these findings provide theoretical basis for the therapeutic use of ophiobolin O.

MicroRNA-7 protects against 1-methyl-4-phenylpyridinium-induced cell death by targeting RelA

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra. Mitochondrial complex I impairment in PD is modeled in vitro by the susceptibility of dopaminergic neurons to the complex I inhibitor 1-methyl-4-phenylpyridinium (MPP+). In the present study, we demonstrate that microRNA-7 (miR-7), which is expressed in tyrosine hydroxylase-positive nigral neurons in mice and humans, protects cells from MPP+-induced toxicity in dopaminergic SH-SY5Y cells, differentiated human neural progenitor ReNcell VM cells, and primary mouse neurons. RelA, a component of nuclear factor-κB (NF-κB), was identified to be downregulated by miR-7 using quantitative proteomic analysis. Through a series of validation experiments, it was confirmed that RelA mRNA is a target of miR-7 and is required for cell death following MPP+ exposure. Further, RelA mediates MPP+-induced suppression of NF-κB activity, which is essential for MPP+-induced cell death. Accordingly, the protective effect of miR-7 is exerted through relieving NF-κB suppression by reducing RelA expression. These findings provide a novel mechanism by which NF-κB suppression, rather than activation, underlies the cell death mechanism following MPP+ toxicity, have implications for the pathogenesis of PD, and suggest miR-7 as a therapeutic target for this disease.

Multidirectional and simultaneous evaluation of gastroschisis-related intestinal damage in chick embryos

PURPOSE

In a chick model of gastroschisis, we aimed to investigate the morphological/cellular, molecular, and ultrastructural changes taking place in gastroschisis-related intestinal damage (GRID).

METHODS

13-Day fertilized eggs were divided into two groups.

CONTROL GROUP

chorio-amnio-allontoic membranes opened and abdominal wall exposed. Gastroschisis group: an anterior abdominal wall defect created after opening membranes. Embryos from both groups were surgically removed on post-fertilization day 19. Intestinal samples were obtained for histopathology, immunohistochemistry, molecular biology, and electron microscopy.

RESULTS

The histopathological grade of intestinal damage which primarily involved mucosal structures was significantly higher in the gastroschisis group when compared to the control group (p<0.001). Immunohistochemically, E-cadherin and synaptophysin immunoreactivity in the gastroschisis group was significantly lower than control group (p<0.05 and p<0.01, respectively), whereas there was no significant difference in laminin and type-4 collagen immunoreactivity between the groups (p>0.05). Molecular analyses indicated a significant decrease in NFκB and IκB expression in the gastroschisis group (p<0.05 and p=0.001, respectively). Electron microscopy showed that the gastroschisis group had considerable ultrastructural damage, manifested by apoptosis in all layers.

CONCLUSIONS

GRID affected all layers but was more prominent in mucosa. The damage may depend on E-cadherin and synaptophysin downregulation. Increased apoptotic activity, associated with decreased NFκB and IκB expression, may be an important component of this multifactorial damaging process.

The cell death response to enteropathogenic Escherichia coli infection

Given the critical roles of inflammation and programmed cell death in fighting infection, it is not surprising that many bacterial pathogens have evolved strategies to inactivate these defences. The causative agent of infant diarrhoea, enteropathogenic Escherichia coli (EPEC), is an extracellular, intestinal pathogen that blocks both inflammation and programmed cell death. EPEC attaches to enterocytes, remains in the gut lumen and utilizes a type III secretion system (T3SS) to inject multiple virulence effector proteins directly into the infected cell, many of which subvert host antimicrobial processes through the disruption of signalling pathways. Recently, T3SS effector proteins from EPEC have been identified that inhibit death receptor-induced apoptosis. Here we review the mechanisms used by EPEC T3SS effectors to manipulate apoptosis and promote host cell survival and discuss the role of these activities during infection.

Tumor necrosis factor alpha promotes the proliferation of human nucleus pulposus cells via nuclear factor-κB, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase

Although tumor necrosis factor alpha (TNF-α) is known to play a critical role in intervertebral disc (IVD) degeneration, the effect of TNF-α on nucleus pulposus (NP) cells has not yet been elucidated. The aim of this study was to explore the effect of TNF-α on proliferation of human NP cells. NP cells were treated with different concentrations of TNF-α. Cell proliferation was determined by cell counting kit-8 (CCK-8) analysis and Ki67 immunofluorescence staining, and expression of cyclin B1 was studied by quantitative real-time RT-PCR. Cell cycle was measured by flow cytometry and cell apoptosis was analyzed using an Annexin V-fluorescein isothiocyanate (FITC) & propidium iodide (PI) apoptosis detection kit. To identify the mechanism by which TNF-α induced proliferation of NP cells, selective inhibitors of major signaling pathways were used and Western blotting was carried out. Treatment with TNF-α increased cell viability (as determined by CCK-8 analysis) and expression of cyclin B1 and the number of Ki67-positive and S-phase NP cells, indicating enhancement of proliferation. Consistent with this, NP cell apoptosis was suppressed by TNF-α treatment. Moreover, inhibition of NF-κB, c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) blocked TNF-α-stimulated proliferation of NP cells. In conclusion, the current findings suggest that the effect of TNF-α on IVD degeneration involves promotion of the proliferation of human NP cells via the NF-κB, JNK, and p38 MAPK pathways.

Peripheral noxious stimulation reduces withdrawal threshold to mechanical stimuli after spinal cord injury: role of tumor necrosis factor alpha and apoptosis

We previously showed that peripheral noxious input after spinal cord injury (SCI) inhibits beneficial spinal plasticity and impairs recovery of locomotor and bladder functions. These observations suggest that noxious input may similarly affect the development and maintenance of chronic neuropathic pain, an important consequence of SCI. In adult rats with a moderate contusion SCI, we investigated the effect of noxious tail stimulation, administered 1 day after SCI on mechanical withdrawal responses to von Frey stimuli from 1 to 28 days after treatment. In addition, because the proinflammatory cytokine tumor necrosis factor alpha (TNFα) is implicated in numerous injury-induced processes including pain hypersensitivity, we assessed the temporal and spatial expression of TNFα, TNF receptors, and several downstream signaling targets after stimulation. Our results showed that unlike sham surgery or SCI only, nociceptive stimulation after SCI induced mechanical sensitivity by 24h. These behavioral changes were accompanied by increased expression of TNFα. Cellular assessments of downstream targets of TNFα revealed that nociceptive stimulation increased the expression of caspase 8 and the active subunit (12 kDa) of caspase 3, indicative of active apoptosis at a time point consistent with the onset of mechanical allodynia. In addition, immunohistochemical analysis revealed distinct morphological signs of apoptosis in neurons and microglia at 24h after stimulation. Interestingly, expression of the inflammatory mediator NFκB was unaltered by nociceptive stimulation. These results suggest that noxious input caudal to the level of SCI can increase the onset and expression of behavioral responses indicative of pain, potentially involving TNFα signaling.

Crohn's disease-associated Escherichia coli survive in macrophages by suppressing NFκB signaling

BACKGROUND

Epidemiological and genetic studies suggest a role for enteric flora in the pathogenesis of Crohn's disease (CD). Crohn's disease-associated Escherichia coli (CDEC) is characterized by their ability to invade epithelial cells and survive and induce high concentration of TNF-α from infected macrophages. However, the molecular mechanisms of CDEC survival in infected macrophages are not completely understood.

METHODS

Intracellular survival of CDEC strain LF82 isolated from inflamed ileum tissue, 13I isolated from inflamed colonic tissue, and control E. coli strains were tested in the murine macrophage cell line, J774A.1 by Gentamicin protection assay. Modulation of intracellular cell signaling pathways by the E. coli strains were assessed by western blot analysis and confocal microscopy.

RESULTS

13I demonstrated increased survival in macrophages with 2.6-fold higher intracellular bacteria compared with LF82, yet both strains induced comparable levels of TNF-α. LF82 and 13I differentially modulated key mitogen-activated protein kinase pathways during the acute phase of infection; LF82 activated all 3 mitogen-activated protein kinase pathways, whereas 13I activated ERK1/2 pathway but not p38 and JNK pathways. Both 13I and LF82 suppressed nuclear translocation of NFκB compared with noninvasive E. coli strains during the acute phase of infection. However, unlike noninvasive E. coli strains, 13I and LF82 infection resulted in chronic activation of NFκB during the later phase of infection.

CONCLUSIONS

Our results showed that CDEC survive in macrophages by initially suppressing NFκB activation. However, persistence of bacterial within macrophages induces chronic activation of NFκB, which correlates with increased TNF-α secretion from infected macrophages.

Comparison of hematopoietic cancer stem cells with normal stem cells leads to discovery of novel differentially expressed SSRs

Tandem repeat expansion in the transcriptomics level has been considered as one of the underlying causes of different cancers. Cancer stem cells are a small portion of cancer cells within the main neoplasm and can remain alive during chemotherapy and re-induce tumor growth. The EST-SSR background of cancer stem cells and possible roles of expressed SSRs in altering normal stem cells to cancer ones have not been investigated yet. Here, SSR distributions in hematopoietic normal and cancer stem cells were compared based on the expressed EST-SSR. One hundred eighty nine and 223 EST-SSRs were identified in cancer and normal stem cells, respectively. The EST-SSR expression pattern was significantly different between normal and cancer stem cells. The frequencies of AC/GT and TA/TA EST-SSRs were about 10% higher in cancer than normal stem cells. Remarkably, the number of triplets in cancer stem cells was 1.5 times higher than that in normal stem cells. GAT EST-SSR was frequent in cancer stem cells, but, conversely, normal stem cells did not express GAT EST-SSR. We suggest this EST-SSR as a novel triplet in cancer stem cell induction. Translating EST-SSRs to amino acids demonstrated that Asp and Ile were more abundant in cancer stem cells compared to normal stem cells. Finally, Gene Ontology (GO) enrichment analysis was carried out on genes containing triplet SSRs and showed that SSRs intentionally visit some specific GO classes. Interestingly, a NF-kappa (nuclear factor-kB) binding transcription factor was significantly hit by SSR instability which is a hallmark for leukemia stem cells. NF-kappa is an over represented transcription factor during cancer progression. It seems that there is a crosstalk between the NF-kB transcription factor and expressed GAT tandem repeat which negatively regulate apoptosis. In addition to better understanding of tumorigenesis, the findings of this study offer new DNA markers for diagnostic purposes and identifying at risk populations. In addition, a new approach for gene discovery in cancer by target analysis of differentially expressed EST-SSRs between cancer and normal stem cells is presented here.

Necroptotic signaling in adaptive and innate immunity

The vertebrate immune system is highly dependent on cell death for efficient responsiveness to microbial pathogens and oncogenically transformed cells. Cell death pathways are vital to the function of many immune cell types during innate, humoral and cellular immune responses. In addition, cell death regulation is imperative for proper adaptive immune self-tolerance and homeostasis. While apoptosis has been found to be involved in several of these roles in immunity, recent data demonstrate that alternative cell death pathways are required. Here, we describe the involvement of a programmed form of cellular necrosis called "necroptosis" in immunity. We consider the signaling pathways that promote necroptosis downstream of death receptors, type I transmembrane proteins of the tumor necrosis factor (TNF) receptor family. The involvement of necroptotic signaling through a "RIPoptosome" assembled in response to innate immune stimuli or genotoxic stress is described. We also characterize the induction of necroptosis following antigenic stimulation in T cells lacking caspase-8 or FADD function. While necroptotic signaling remains poorly understood, it is clear that this pathway is an essential component to effective vertebrate immunity.