30 Years of NF-κB: A Blossoming of Relevance to Human Pathobiology

How do cancer cells replenish their fuel supply?

BACKGROUND

Multiple genetic changes, availability of cellular nutrients and metabolic alterations play a pivotal role in oncogenesis AIMS: We focus on cancer cell's metabolic properties, and we outline the cross talks between cellular oncogenic growth pathways in cancer metabolism. The review also provides a synopsis of the relevant cancer drugs targeting metabolic activities that are at various stages of clinical development.

METHODS

We review literature published within the last decade to include select articles that have highlighted energy metabolism crucial to the development of cancer phenotypes.

RESULTS

Cancer cells maintain their potent metabolism and keep a balanced redox status by enhancing glycolysis and autophagy and rerouting Krebs cycle intermediates and products of β-oxydation.

CONCLUSIONS

The processes underlying cancer pathogenesis are extremely complex and remain elusive. The new field of systems biology provides a mathematical framework in which these homeostatic dysregulation principles may be examined for better understanding of cancer phenotypes. Knowledge of key players in cancer-related metabolic reprograming may pave the way for new therapeutic metabolism-targeted drugs and ultimately improve patient care.

Inflammatory cell death in intestinal pathologies

The intestinal tract is a site of intense immune cell activity that is poised to mount an effective response against a pathogen and yet maintain tolerance toward commensal bacteria and innocuous dietary antigens. The role of cell death in gut pathologies is particularly important as the intestinal epithelium undergoes self-renewal every 4-7 days through a continuous process of cell death and cell division. Cell death is also required for removal of infected, damaged, and cancerous cells. Certain forms of cell death trigger inflammation through release of damage-associated molecular patterns. Further, molecules involved in cell death decisions also moonlight as critical nodes in immune signaling. The manner of cell death is, therefore, highly instructive of the immunological consequences that ensue. Perturbations in cell death pathways can impact the regulation of the immune system with deleterious consequences. In this review, we discuss the various forms of cell death with a special emphasis on lytic cell death pathways of pyroptosis and necroptosis and their implications in inflammation and cancer in the gut. Understanding the implications of distinct cell death pathways will help in the development of therapeutic interventions in intestinal pathologies.

Shared and independent functions of aPKCλ and Par3 in skin tumorigenesis

The polarity proteins Par3 and aPKC are key regulators of processes altered in cancer. Par3/aPKC are thought to dynamically interact with Par6 but increasing evidence suggests that aPKC and Par3 also exert complex-independent functions. Whereas aPKCλ serves as tumor promotor, Par3 can either promote or suppress tumorigenesis. Here we asked whether and how Par3 and aPKCλ genetically interact to control two-stage skin carcinogenesis. Epidermal loss of Par3, aPKCλ, or both, strongly reduced tumor multiplicity and increased latency but inhibited invasion to similar extents, indicating that Par3 and aPKCλ function as a complex to promote tumorigenesis. Molecularly, Par3/aPKCλ cooperate to promote Akt, ERK and NF-κB signaling during tumor initiation to sustain growth, whereas aPKCλ dominates in promoting survival. In the inflammatory tumorigenesis phase Par3/aPKCλ cooperate to drive Stat3 activation and hyperproliferation. Unexpectedly, the reduced inflammatory signaling did not alter carcinogen-induced immune cell numbers but reduced IL-4 Receptor-positive stromal macrophage numbers in all mutant mice, suggesting that epidermal aPKCλ and Par3 promote a tumor-permissive environment. Importantly, aPKCλ also serves a distinct, carcinogen-independent role in controlling skin immune cell homeostasis. Collectively, our data demonstrates that Par3 and aPKCλ cooperate to promote skin tumor initiation and progression, likely through sustaining growth, survival, and inflammatory signaling.

Aqueous extracts from Uncaria tomentosa (Willd. ex Schult.) DC. reduce bronchial hyperresponsiveness and inflammation in a murine model of asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Uncaria tomentosa (Willd. Ex Schult) DC is used by indigenous tribes in the Amazonian region of Central and South America to treat inflammation, allergies and asthma. The therapeutic properties of U. tomentosa have been attributed to the presence of tetracyclic and pentacyclic oxindole alkaloids and to phenolic acids.

AIMS OF THE STUDY

To characterize aqueous bark extracts (ABE) and aqueous leaf extracts (ALE) of U. tomentosa and to compare their anti-inflammatory effects.

MATERIALS AND METHODS

Constituents of the extracts were identified by ultra performance liquid chromatography-mass spectrometry. Anti-inflammatory activities were assessed in vitro by exposing lipopolysaccharide-stimulated macrophage cells (RAW264.7-Luc) to ABE, ALE and standard mitraphylline. In vivo assays were performed using a murine model of ovalbumin (OVA)-induced asthma. OVA-sensitized animals were treated with ABE or ALE while controls received dexamethasone or saline solution. Bronchial hyperresponsiveness, production of Th1 and Th2 cytokines, total and differential counts of inflammatory cells in the bronchoalveolar lavage (BAL) and lung tissue were determined.

RESULTS

Mitraphylline, isomitraphylline, chlorogenic acid and quinic acid were detected in both extracts, while isorhyncophylline and rutin were detected only in ALE. ABE, ALE and mitraphylline inhibited the transcription of nuclear factor kappa-B in cell cultures, ALE and mitraphylline reduced the production of interleukin (IL)-6, and mitraphylline reduced production of tumor necrosis factor-alpha. Treatment with ABE and ALE at 50 and 200 mg kg^-1, respectively, reduced respiratory elastance and tissue damping and elastance. ABE and ALE reduced the number of eosinophils in BAL, while ALE at 200 mg kg^-1 reduced the levels of IL-4 and IL-5 in the lung homogenate. Peribronchial inflammation was significantly reduced by treatment with ABE and ALE at 50 and 100 mg kg^-1 respectively.

CONCLUSION

The results clarify for the first time the anti-inflammatory activity of U. tomentosa in a murine model of asthma. Although ABE and ALE exhibited distinct chemical compositions, both extracts inhibited the production of pro-inflammatory cytokines in vitro. In vivo assays revealed that ABE was more effective in treating asthmatic inflammation while ALE was more successful in controlling respiratory mechanics. Both extracts may have promising applications in the phytotherapy of allergic asthma.

The Crosstalk of Endoplasmic Reticulum (ER) Stress Pathways with NF-κB: Complex Mechanisms Relevant for Cancer, Inflammation and Infection

Stressful conditions occuring during cancer, inflammation or infection activate adaptive responses that are controlled by the unfolded protein response (UPR) and the nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB) signaling pathway. These systems can be triggered by chemical compounds but also by cytokines, toll-like receptor ligands, nucleic acids, lipids, bacteria and viruses. Despite representing unique signaling cascades, new data indicate that the UPR and NF-κB pathways converge within the nucleus through ten major transcription factors (TFs), namely activating transcription factor (ATF)4, ATF3, CCAAT/enhancer-binding protein (CEBP) homologous protein (CHOP), X-box-binding protein (XBP)1, ATF6α and the five NF-κB subunits. The combinatorial occupancy of numerous genomic regions (enhancers and promoters) coordinates the transcriptional activation or repression of hundreds of genes that collectively determine the balance between metabolic and inflammatory phenotypes and the extent of apoptosis and autophagy or repair of cell damage and survival. Here, we also discuss results from genetic experiments and chemical activators of endoplasmic reticulum (ER) stress that suggest a link to the cytosolic inhibitor of NF-κB (IκB)α degradation pathway. These data show that the UPR affects this major control point of NF-κB activation through several mechanisms. Taken together, available evidence indicates that the UPR and NF-κB interact at multiple levels. This crosstalk provides ample opportunities to fine-tune cellular stress responses and could also be exploited therapeutically in the future.

Pterostilbene and 4'-Methoxyresveratrol Inhibited Lipopolysaccharide-Induced Inflammatory Response in RAW264.7 Macrophages

Pterostilbene (Pte) and 4′-Methoxyresveratrol (4MR) are methylated derivatives of resveratrol. We investigated the anti-inflammatory effect of Pte and 4MR in lipopolysaccharide (LPS)-stimulated RAW264.7 murine macrophages. Both Pte and 4MR significantly reduced LPS-induced nitric oxide release by inhibiting the inducible nitric oxide synthase mRNA expression. Moreover, both of them inhibited LPS-induced mRNA expression of inflammatory cytokines including monocyte chemoattractant protein (MCP)-1, interleukin (IL)-6 and IL-1β, and tumor necrosis factor α (TNF-α), and attenuated LPS-induced nuclear factor-κB (NF-κB) activation by decreasing p65 phosphorylation. In addition, 4MR but not Pte inhibited LPS-induced the activator protein (AP)-1 pathway in RAW 264.7 macrophages. Further study suggested that Pte had an inhibitory effect on extracellular regulated protein kinases (ERK) and p38 activation, but not on c-Jun N-terminal kinase (JNK), while 4MR had an inhibitory effect on JNK and p38 activation, but not on ERK. Taken together, our data suggested that Pte induced anti-inflammatory activity by blocking mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways, while 4MR showed anti-inflammatory activity through suppression of MAPK, AP-1, and NF-κB signaling pathways in LPS-treated RAW 264.7 macrophages.

Suppression of lung inflammation by the methanol extract of Spilanthes acmella Murray is related to differential regulation of NF-κB and Nrf2

ETHNOPHARMACOLOGICAL RELEVANCE

Although Spilanthes acmella has been used to relieve inflammation, fever, pain, or infection in traditional Asian medicine, experimental evidence supporting these functions is scarce. Here, we examined an anti-inflammatory function and a possible underlying mechanism of S. acmella Murray (SAM).

MATERIALS AND METHOD

The methanol extract of SAM was fingerprinted by HPLC. C57BL/6 mice were administered with a single intratracheal (i.t.) LPS and 2 h later with a single i.t. SAM. The effect of SAM on lung inflammation was assessed by histology, semi-quantitative RT-PCR, and MPO assay of lung tissue. The effects of SAM on a pro-inflammatory factor NF-κB and an anti-inflammatory factor Nrf2 were analyzed by immunoblotting of nuclear proteins and by semi-quantitative RT-PCR analysis of mRNA of the genes governed by these transcription factors. V5-Nrf2 was precipitated by an anti-V5 antibody and the ubiquitinated V5-Nrf2 was revealed by immunoblotting of HA-tagged ubiquitin.

RESULTS

The i.t. SAM robustly diminished a neutrophilic lung inflammation induced by i.t. LPS treatment of mice. In RAW 264.7 cells, SAM suppressed the nuclear localization of NF-κB and the expression of NF-κB-dependent cytokine genes. SAM increased the level of Nrf2 in the nucleus and the expression of Nrf2-dependent genes while suppressing ubiquitination of Nrf2.

CONCLUSION

Our results suggest that SAM can suppress a neutrophilic inflammation in mouse lungs, which is associated with suppressed NF-κB and activated Nrf2. Our results provide experimental evidence supporting the anti-inflammatory function of S. acmella.

Hepatoprotective Effect of Wedelolactone against Concanavalin A-Induced Liver Injury in Mice

Eclipta prostrata L. is a traditional Chinese herbal medicine that has been used in the treatment of liver diseases. However, its biological mechanisms remain elusive. The current study aimed to investigate the hepatoprotective effect of wedelolactone, a major coumarin ingredient of Eclipta prostrata L., on immune-mediated liver injury. Using the well-established animal model of Concanavalin A (ConA)-induced hepatitis (CIH), we found that pretreatment of mice with wedelolactone markedly reduced both the serum levels of transaminases and the severity of liver damage. We further investigated the mechanisms of the protective effect of wedelolactone. In mice treated with wedelolactone prior to the induction of CIH, increases of serum concentrations of tumor necrosis factor (TNF)-[Formula: see text], interferon (IFN)-[Formula: see text], and interleukin (IL)-6 were dramatically attenuated. Additionally, expressions of the interferon-inducible chemokine (C-X-C motif) ligand 10 gene CXCL10 and intercellular adhesion molecule 1 gene ICAM1 were lower in livers of the treated mice. Moreover, wedelolactone-treated CIH mice exhibited reduced leukocyte infiltration and T-cell activation in liver. Furthermore, wedelolactone suppressed the activity of nuclear factor-kappa B (NF-[Formula: see text]B), a critical transcriptional factor of the above-mentioned inflammatory cytokines by limiting the phosphorylation of I kappa B alpha (I[Formula: see text]B[Formula: see text] and p65. In conclusion, these findings demonstrate the inhibitory potential of wedelolactone in immune-mediated liver injury in vivo, and show that this protection is associated with modulation of the NF-[Formula: see text]B signaling pathway.

Inhibition of v-rel-Induced Oncogenesis through microRNA Targeting

Several studies have shown that microRNA-targeting is an effective strategy for the selective control of tissue-tropism and pathogenesis of both DNA and RNA viruses. However, the exploitation of microRNA-targeting for the inhibition of transformation by oncogenic viruses has not been studied. The v-rel oncoprotein encoded by reticuloendotheliosis virus T strain (Rev-T) is a member of the rel/NF-κB family of transcription factors capable of transforming primary chicken spleen and bone marrow cells. Here, by engineering the target sequence of endogenous microRNA miR-142 downstream of the v-rel gene in a Replication-Competent ALV (avian leukosis virus) long terminal repeat (LTR) with a splice acceptor (RCAS) vector and using a v-rel-induced transformation model of chicken embryonic splenocyte cultures, we show that hematopoietic-specific miR-142 can inhibit the v-rel-induced transformation, and that this inhibition effect is due to the silencing of v-rel expression. The data supports the idea that microRNA-targeting can be used to inhibit viral oncogene-induced oncogenesis.

Therapeutic Potential of Sclareol in Experimental Models of Rheumatoid Arthritis

Previous studies have shown that the natural diterpene compound, sclareol, potentially inhibits inflammation, but it has not yet been determined whether sclareol can alleviate inflammation associated with rheumatoid arthritis (RA). Here, we utilized human synovial cell line, SW982, and an experimental murine model of rheumatoid arthritis, collagen-induced arthritis (CIA), to evaluate the therapeutic effects of sclareol in RA. Arthritic DBA/1J mice were dosed with 5 and 10 mg/kg sclareol intraperitoneally every other day over 21 days. Arthritic severity was evaluated by levels of anti-collagen II (anti-CII) antibody, inflammatory cytokines, and histopathologic examination of knee joint tissues. Our results reveal that the serum anti-CII antibody, cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-17, as well as Th17 and Th1 cell population in inguinal lymph nodes, were significantly lower in sclareol-treated mice compared to the control group. Also, the sclareol treatment groups showed reduced swelling in the paws and lower histological arthritic scores, indicating that sclareol potentially mitigates collagen-induced arthritis. Furthermore, IL-1β-stimulated SW982 cells secreted less inflammatory cytokines (TNF-α and IL-6), which is associated with the downregulation of p38-mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), and NF-κB pathways. Overall, we demonstrate that sclareol could relieve arthritic severities by modulating excessive inflammation and our study merits the pharmaceutical development of sclareol as a therapeutic treatment for inflammation associated with RA.

Need (more than) two to Tango: Multiple tools to adapt to changes in oxygen availability

Oxygen is a fundamental element for the life of a large number of living organisms allowing an efficient energetic utilization of substrates. Organisms relying on oxygen evolved complex structures for oxygen delivery and biochemical machineries dealing with its safe utilization and the ability to overcome the potentially harmful consequences of changes in oxygen availability. On fact, cells composing complex Eukaryotic organisms are set to live within an optimum narrow range of oxygen, quite specific for each cell type. Minute modifications of oxygen availability, either positive or negative, induce the expression of specific genes, the major actors of this responses being the transcription factors HIF and Nrf2 that control the attempt to cope with low oxygen (hypoxia) or to either high oxygen or to an oxygen "overflow," respectively. This review describes the interaction between these two transcription factors and their interaction with the transcription factor NF-κB acting as a pivotal determinant of final cell response. © 2018 BioFactors, 44(3):207-218, 2018.

Versatile and efficient chromatin pull-down methodology based on DNA triple helix formation

The goal of present paper is to develop a reliable DNA-based method for isolation of protein complexes bound to DNA (Isolation of DNA Associated Proteins: IDAP). We describe a robust and versatile procedure to pull-down chromatinized DNA sequences-of-interest by formation of a triple helix between a sequence tag present in the DNA and a complementary triple helix forming oligonucleotide (TFO) coupled to a desthiobiotin residue. Following optimization to insure efficient recovery of native plasmids via TFO probe in vitro, the procedure is shown to work under various experimental situations. For instance, it allows capture proteins associated to plasmids hosted in E. coli, and is also successfully applied to recovering nucleosomes in vitro opening many possibilities to study post translational modifications of histones in a genuine nucleosome context. Incubation in human nuclear extracts of a plasmid carrying a NF-κB model promoter is shown to pull-down a specific transcription factor. Finally, isolation of a specific locus from human genomic chromatin has been successfully achieved (Chromatin-of-Interest Fragment Isolation: CoIFI). In conclusion, the methodology can be implemented for capturing proteins that specifically bind to any sequence-of-interest, DNA adduct or secondary structure provided a short sequence tag for triple helix formation is located nearby.

The Many Roles of Ubiquitin in NF-κB Signaling

The nuclear factor κB (NF-κB) signaling pathway ubiquitously controls cell growth and survival in basic conditions as well as rapid resetting of cellular functions following environment changes or pathogenic insults. Moreover, its deregulation is frequently observed during cell transformation, chronic inflammation or autoimmunity. Understanding how it is properly regulated therefore is a prerequisite to managing these adverse situations. Over the last years evidence has accumulated showing that ubiquitination is a key process in NF-κB activation and its resolution. Here, we examine the various functions of ubiquitin in NF-κB signaling and more specifically, how it controls signal transduction at the molecular level and impacts in vivo on NF-κB regulated cellular processes.

SAMHD1 suppresses innate immune responses to viral infections and inflammatory stimuli by inhibiting the NF-κB and interferon pathways

Sterile alpha motif and HD-domain-containing protein 1 (SAMHD1) blocks replication of retroviruses and certain DNA viruses by reducing the intracellular dNTP pool. SAMHD1 has been suggested to down-regulate IFN and inflammatory responses to viral infections, although the functions and mechanisms of SAMHD1 in modulating innate immunity remain unclear. Here, we show that SAMHD1 suppresses the innate immune responses to viral infections and inflammatory stimuli by inhibiting nuclear factor-κB (NF-κB) activation and type I interferon (IFN-I) induction. Compared with control cells, infection of SAMHD1-silenced human monocytic cells or primary macrophages with Sendai virus (SeV) or HIV-1, or treatment with inflammatory stimuli, induces significantly higher levels of NF-κB activation and IFN-I induction. Exogenous SAMHD1 expression in cells or SAMHD1 reconstitution in knockout cells suppresses NF-κB activation and IFN-I induction by SeV infection or inflammatory stimuli. Mechanistically, SAMHD1 inhibits NF-κB activation by interacting with NF-κB1/2 and reducing phosphorylation of the NF-κB inhibitory protein IκBα. SAMHD1 also interacts with the inhibitor-κB kinase ε (IKKε) and IFN regulatory factor 7 (IRF7), leading to the suppression of the IFN-I induction pathway by reducing IKKε-mediated IRF7 phosphorylation. Interactions of endogenous SAMHD1 with NF-κB and IFN-I pathway proteins were validated in human monocytic cells and primary macrophages. Comparing splenocytes from SAMHD1 knockout and heterozygous mice, we further confirmed SAMHD1-mediated suppression of NF-κB activation, suggesting an evolutionarily conserved property of SAMHD1. Our findings reveal functions of SAMHD1 in down-regulating innate immune responses to viral infections and inflammatory stimuli, highlighting the importance of SAMHD1 in modulating antiviral immunity.

Strategies targeting cellular senescence

Cellular senescence is a physiological phenomenon that has both beneficial and detrimental consequences. Senescence limits tumorigenesis and tissue damage throughout the lifetime. However, at the late stages of life, senescent cells increasingly accumulate in tissues and might also contribute to the development of various age-related pathologies. Recent studies have revealed the molecular pathways that preserve the viability of senescent cells and the ones regulating their immune surveillance. These studies provide essential initial insights for the development of novel therapeutic strategies for targeting senescent cells. At the same time they stress the need to understand the limitations of the existing strategies, their efficacy and safety, and the possible deleterious consequences of senescent cell elimination. Here we discuss the existing strategies for targeting senescent cells and upcoming challenges in translating these strategies into safe and efficient therapies. Successful translation of these strategies could have implications for treating a variety of diseases at old age and could potentially reshape our view of health management during aging.

An Autoimmune Disease-Associated Risk Variant in the TNFAIP3 Gene Plays a Protective Role in Brucellosis That Is Mediated by the NF-κB Signaling Pathway

Naturally occurring functional variants (rs148314165 and rs200820567, collectively referred to as TT>A) reduce the expression of the tumor necrosis factor alpha-induced protein 3 (TNFAIP3) gene, a negative regulator of NF-κB signaling, and predispose individuals to autoimmune disease. In this analysis, we conducted a genetic association study of the TT>A variants in 1,209 controls and 150 patients with brucellosis, an infectious disease, and further assessed the role of the variants in brucellosis. Our data demonstrated that the TT>A variants were correlated with cases of brucellosis (P = 0.002; odds ratio [OR] = 0.34) and with individuals who had a positive serum agglutination test (SAT) result (titer of >1/160) (P = 4.2 × 10-6; OR = 0.23). A functional study demonstrated that brucellosis patients carrying the protective allele (A) showed significantly lower expression levels of the TNFAIP3 gene in their peripheral blood mononuclear cells and showed increased NF-κB signaling. Monocytes from individuals carrying the A allele that were stimulated with Brucella abortus had lower mRNA levels of TNFAIP3 and produced more interleukin-10 (IL-10), IL-6, and IL-1β than those from TT allele carriers. These data showed that autoimmune disease-associated risk variants, TT>A, of the TNFAIP3 locus play a protective role in the pathogenesis of brucellosis. Our findings suggest that a disruption of the normal function of the TNFAIP3 gene might serve as a therapeutic target for the treatment of brucellosis.

Kaempferol attenuates hyperglycemia-induced cardiac injuries by inhibiting inflammatory responses and oxidative stress

PURPOSE

Suppression of inflammation and oxidative stress is an attractive strategy to against diabetic cardiomyopathy (DCM). Kaempferol (KPF) exerts both anti-inflammatory and antioxidant pharmacological properties. However, little is known about the effect of KPF on protecting myocardial injury in diabetes. The present study aimed to investigate the effect of KPF on DCM and underlying mechanism.

METHODS

Anti-inflammation and anti-oxidative stress activities of KPF were evaluated in H9c2 cells or primary cardiomyocytes by real-time quantitate PCR, immunoblotting, immunofluorescence, ELISA, and FACS. Streptozotocin (STZ)-induced type 1 diabetes mellitus mice were constructed. Corresponding to experiments in vitro, the therapeutic effect of KPF was also assessed using heart tissues from mice.

RESULTS

KPF significantly inhibited high glocose (HG) induced expression of inflammatory cytokines and generation of ROS, leading to reduced fibrotic responses and cell apoptosis in vitro. KPF mediated DCM protective effects through inhibiting nuclear factor-κB (NF-κB) nucleus translocation and activating nuclear factor-erythroid 2 p45-related factor-2 (Nrf-2). In STZ-induced type 1 diabetic mouse model, KPF prevented diabetes-induced cardiac fibrosis and apoptosis. These changes were also accompanied by reducing inflammation and oxidative stress in diabetic mice hearts.

CONCLUSION

KPF is a potential therapeutic agent for the treatment of DCM, mechanically linked to inhibition of NF-κB and Nrf-2 activation.

Molecular Classification of Primary Immunodeficiencies of T Lymphocytes

Proper regulation of the immune system is required for protection against pathogens and preventing autoimmune disorders. Inborn errors of the immune system due to inherited or de novo germline mutations can lead to the loss of protective immunity, aberrant immune homeostasis, and the development of autoimmune disease, or combinations of these. Forward genetic screens involving clinical material from patients with primary immunodeficiencies (PIDs) can vary in severity from life-threatening disease affecting multiple cell types and organs to relatively mild disease with susceptibility to a limited range of pathogens or mild autoimmune conditions. As central mediators of innate and adaptive immune responses, T cells are critical orchestrators and effectors of the immune response. As such, several PIDs result from loss of or altered T cell function. PID-associated functional defects range from complete absence of T cell development to uncontrolled effector cell activation. Furthermore, the gene products of known PID causal genes are involved in diverse molecular pathways ranging from T cell receptor signaling to regulators of protein glycosylation. Identification of the molecular and biochemical cause of PIDs can not only guide the course of treatment for patients, but also inform our understanding of the basic biology behind T cell function. In this chapter, we review PIDs with known genetic causes that intrinsically affect T cell function with particular focus on perturbations of biochemical pathways.

Recent advances in understanding the biology of marginal zone lymphoma

There are three different marginal zone lymphomas (MZLs): the extranodal MZL of mucosa-associated lymphoid tissue (MALT) type (MALT lymphoma), the splenic MZL, and the nodal MZL. The three MZLs share common lesions and deregulated pathways but also present specific alterations that can be used for their differential diagnosis. Although trisomies of chromosomes 3 and 18, deletions at 6q23, deregulation of nuclear factor kappa B, and chromatin remodeling genes are frequent events in all of them, the three MZLs differ in the presence of recurrent translocations, mutations affecting the NOTCH pathway, and the transcription factor Kruppel like factor 2 ( KLF2) or the receptor-type protein tyrosine phosphatase delta ( PTPRD). Since a better understanding of the molecular events underlying each subtype may have practical relevance, this review summarizes the most recent and main advances in our understanding of the genetics and biology of MZLs.

Nuclear Factor-κB Promotes Urothelial Tumorigenesis and Cancer Progression via Cooperation with Androgen Receptor Signaling

We investigated the role of NF-κB in the development and progression of urothelial cancer as well as cross-talk between NF-κB and androgen receptor (AR) signals in urothelial cells. Immunohistochemistry in surgical specimens showed that the expression levels of NF-κB/p65 (P = 0.015)/phospho-NF-κB/p65 (P < 0.001) were significantly elevated in bladder tumors, compared with those in nonneoplastic urothelial tissues. The rates of phospho-NF-κB/p65 positivity were also significantly higher in high-grade (P = 0.015)/muscle-invasive (P = 0.033) tumors than in lower grade/non-muscle-invasive tumors. Additionally, patients with phospho-NF-κB/p65-positive muscle-invasive bladder cancer had significantly higher risks of disease progression (P < 0.001) and cancer-specific mortality (P = 0.002). In immortalized human normal urothelial SVHUC cells stably expressing AR, NF-κB activators and inhibitors accelerated and prevented, respectively, their neoplastic transformation induced by a chemical carcinogen 3-methylcholanthrene. Bladder tumors were identified in 56% (mock), 89% (betulinic acid), and 22% (parthenolide) of N-butyl-N-(4-hydroxybutyl)nitrosamine-treated male C57BL/6 mice at 22 weeks of age. NF-κB activators and inhibitors also significantly induced and reduced, respectively, cell proliferation/migration/invasion of AR-positive bladder cancer lines, but not AR-knockdown or AR-negative lines, and their growth in xenograft-bearing mice. In both nonneoplastic and neoplastic urothelial cells, NF-κB activators/inhibitors upregulated/downregulated, respectively, AR expression, whereas AR overexpression was associated with increases in the expression levels of NF-κB/p65 and phospho-NF-κB/p65. Thus, NF-κB appeared to be activated in bladder cancer, which was associated with tumor progression. NF-κB activators/inhibitors were also found to modulate tumorigenesis and tumor outgrowth in AR-activated urothelial cells. Accordingly, NF-κB inhibition, together with AR inactivation, has the potential of being an effective chemopreventive and/or therapeutic approach for urothelial carcinoma. Mol Cancer Ther; 17(6); 1303-14. ©2018 AACR.

Mycobacterium tuberculosis Mce2E suppresses the macrophage innate immune response and promotes epithelial cell proliferation

The intracellular pathogen Mycobacterium tuberculosis (Mtb) can survive in the host and cause disease by interfering with a variety of cellular functions. The mammalian cell entry 2 (mce2) operon of Mtb has been shown to contribute to tuberculosis pathogenicity. However, little is known about the regulatory roles of Mtb Mce2 family proteins towards host cellular functions. Here we show that the Mce2 family protein Mce2E suppressed the macrophage innate immune response and promoted epithelial cell proliferation. Mce2E inhibited activation of the extracellular signal-regulated kinase (ERK) and Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) signaling pathways in a non-canonical D motif (a MAPK-docking motif)-dependent manner, leading to reduced expression of TNF and IL-6 in macrophages. Furthermore, Mce2E promoted proliferation of human lung epithelium-derived lung adenoma A549 cells by inhibiting K48-linked polyubiquitination of eEF1A1 in a β strand region-dependent manner. In summary, Mce2E is a novel multifunctional Mtb virulence factor that regulates host cellular functions in a niche-dependent manner. Our data suggest a potential novel target for TB therapy.

Emerging Alphaviruses Are Sensitive to Cellular States Induced by a Novel Small-Molecule Agonist of the STING Pathway

The type I interferon (IFN) system represents an essential innate immune response that renders cells resistant to virus growth via the molecular actions of IFN-induced effector proteins. IFN-mediated cellular states inhibit growth of numerous and diverse virus types, including those of known pathogenicity as well as potentially emerging agents. As such, targeted pharmacologic activation of the IFN response may represent a novel therapeutic strategy to prevent infection or spread of clinically impactful viruses. In light of this, we employed a high-throughput screen to identify small molecules capable of permeating the cell and of activating IFN-dependent signaling processes. Here we report the identification and characterization of N-(methylcarbamoyl)-2-{[5-(4-methylphenyl)-1,3,4-oxadiazol-2-yl]sulfanyl}-2-phenylacetamide (referred to as C11), a novel compound capable of inducing IFN secretion from human cells. Using reverse genetics-based loss-of-function assays, we show that C11 activates the type I IFN response in a manner that requires the adaptor protein STING but not the alternative adaptors MAVS and TRIF. Importantly, treatment of cells with C11 generated a cellular state that potently blocked replication of multiple emerging alphavirus types, including chikungunya, Ross River, Venezuelan equine encephalitis, Mayaro, and O'nyong-nyong viruses. The antiviral effects of C11 were subsequently abrogated in cells lacking STING or the type I IFN receptor, indicating that they are mediated, at least predominantly, by way of STING-mediated IFN secretion and subsequent autocrine/paracrine signaling. This work also allowed characterization of differential antiviral roles of innate immune signaling adaptors and IFN-mediated responses and identified MAVS as being crucial to cellular resistance to alphavirus infection.IMPORTANCE Due to the increase in emerging arthropod-borne viruses, such as chikungunya virus, that lack FDA-approved therapeutics and vaccines, it is important to better understand the signaling pathways that lead to clearance of virus. Here we show that C11 treatment makes human cells refractory to replication of a number of these viruses, which supports its value in increasing our understanding of the immune response and viral pathogenesis required to establish host infection. We also show that C11 depends on signaling through STING to produce antiviral type I interferon, which further supports its potential as a therapeutic drug or research tool.

Induction of INKIT by Viral Infection Negatively Regulates Antiviral Responses through Inhibiting Phosphorylation of p65 and IRF3

The transcription factors p65 and IRF3 play key roles in the induction of cellular antiviral responses. Phosphorylation of p65 and IRF3 is required for their activity and constitutes a key checkpoint. Here we report that viral infection induced upregulation of INKIT, an inhibitor for NF-κB and IRF3 that restricted innate antiviral responses by blocking phosphorylation of p65 and IRF3. INKIT overexpression inhibited virus-induced phosphorylation of p65 and IRF3 and expression of downstream genes. In contrast, knockdown or knockout of INKIT had the opposite effect: Inkit^-/- mice produced elevated levels of type I interferons and proinflammatory cytokines and were more resistant to lethal viral infection compared to wild-type. INKIT interacted with IKKα/β and TBK1/IKKɛ, impairing the recruitment and phosphorylation of p65 and IRF3. Viral infection induced IKK-mediated phosphorylation of INKIT at Ser58, resulting in its dissociation from the IKKs. Our findings thus uncover INKIT as a regulator of innate antiviral responses.

TAK1 restricts spontaneous NLRP3 activation and cell death to control myeloid proliferation

The NLRP3 inflammasome protects the host against microbial infections. In this study, Malireddi et al. demonstrate the critical role of TAK1 in restricting RIPK1 signaling to inhibit spontaneous NLRP3 inflammasome activation and cell death, which may be targeted for treatment of myeloid proliferation.

The NOD-like receptor (NLR)–P3 inflammasome is a global sensor of infection and stress. Elevated NLRP3 activation levels are associated with human diseases, but the mechanisms controlling NLRP3 inflammasome activation are largely unknown. Here, we show that TGF-β activated kinase-1 (TAK1) is a central regulator of NLRP3 inflammasome activation and spontaneous cell death. Absence of TAK1 in macrophages induced spontaneous activation of the NLRP3 inflammasome without requiring toll-like receptor (TLR) priming and subsequent activating signals, suggesting a distinctive role for TAK1 in maintaining NLRP3 inflammasome homeostasis. Autocrine tumor necrosis factor (TNF) signaling in the absence of TAK1 induced spontaneous RIPK1-dependent NLRP3 inflammasome activation and cell death. We further showed that TAK1 suppressed homeostatic NF-κB and extracellular signal–related kinase (ERK) activation to limit spontaneous TNF production. Moreover, the spontaneous inflammation resulting from TAK1-deficient macrophages drives myeloid proliferation in mice, and was rescued by RIPK1 deficiency. Overall, these studies identify a critical role for TAK1 in maintaining NLRP3 inflammasome quiescence and preserving cellular homeostasis and survival.

A poly(beta-amino ester) activates macrophages independent of NF-κB signaling

Nucleic acid delivery vehicles are poised to play an important role in delivering gene therapy for vaccines and immunotherapies, and in delivering nucleic acid based adjuvants. A number of common polymeric delivery vehicles used in nucleic acid delivery have recently been shown to interact with immune cells and directly stimulate immunogenic responses, particularly in particle form. Poly(beta-amino esters) were designed for nucleic acid delivery and have demonstrated promising performance in a number of vaccine and therapeutic studies. Yet, little work has characterized the mechanisms by which these polymers activate immune cells. Here we demonstrate that a poly(beta-amino ester) activates antigen presenting cells in soluble and particulate forms, and that these effects are independent of TLR signaling pathways. Moreover, we show the polymers induce activation independent of NF-κB signaling, but do activate IRF, an important innate inflammatory pathway. New knowledge linking physicochemical features of poly(beta-amino esters) or other polymeric carriers to inflammatory mechanisms could support more rational design approaches for vaccines and immunotherapies harnessing these materials.

SIGNIFICANCE STATEMENT

The last several years have brought exciting work exploring biomaterials as delivery vehicles for immunotherapies, vaccines, and gene therapies. However, a gap remains between the striking finding that many biomaterials exhibit intrinsic immunogenic features, and the specific structural properties that drive these responses. The results in the current study indicate PBAEs cause macrophage activation by pathways that are distinct from pathways activated by common vaccine and immunotherapies components, such as toll-like receptor agonists. Thus, the work reveals new mechanistic details that can be exploited in investigating other materials, and to support more rational design of future biomaterial vaccines and immunotherapy carriers.

Effects of Natural Polyphenols on the Expression of Drug Efflux Transporter P-Glycoprotein in Human Intestinal Cells

The drug efflux transporter P-glycoprotein, which is encoded by MDR1 (ABCB1), plays important roles in drug absorption, distribution, and elimination. We previously reported that dietary polyphenols such as quercetin, curcumin, honokiol, magnolol, caffeic acid phenetyl ester (CAPE), xanthohumol, and anacardic acid inhibit P-glycoprotein-mediated drug transport. In the present study, we investigated the effects of polyphenols on the expression of P-glycoprotein using human intestinal epithelial LS174T cells and a reporter plasmid expressing 10.2 kbp of the upstream regulatory region of MDR1. Honokiol, magnolol, CAPE, xanthohumol, and anacardic acid activated the MDR1 promoter in LS174T cells, and the cellular uptake of rhodamine 123 and calcein-AM, fluorescent substrates of P-glycoprotein, decreased in polyphenol-treated LS174T cells. These results suggest that dietary natural polyphenols can induce the drug efflux transporter P-glycoprotein and have the potential to promote food-drug interactions.

Ginkgolide C Alleviates Myocardial Ischemia/Reperfusion-Induced Inflammatory Injury via Inhibition of CD40-NF-κB Pathway

Increasing evidence shows that inflammation plays a vital role in the occurrence and development of ischemia/reperfusion (I/R). Suppression of excessive inflammation can ameliorate impaired cardiac function, which shows therapeutic potential for clinical treatment of myocardial ischemia/reperfusion (MI/R) diseases. In this study, we investigated whether Ginkgolide C (GC), a potent anti-inflammatory flavone, extenuated MI/R injury through inhibition of inflammation. In vivo, rats with the occlusion of the left anterior descending (LAD) coronary artery were applied to mimic MI/R injury. In vitro, primary cultured neonatal ventricular myocytes exposed to hypoxia/reoxygenation (H/R) were applied to further discuss the anti-H/R injury property of GC. The results revealed that GC significantly improved the symptoms of MI/R injury, as evidenced by reducing infarct size, preventing myofibrillar degeneration and reversing the mitochondria dysfunction. Moreover, histological analysis and Myeloperoxidase (MPO) activity measurement showed that GC remarkably suppressed Polymorphonuclears (PMNs) infiltration and ameliorated the histopathological damage. Furthermore, GC pretreatment was shown to improve H/R-induced ventricular myocytes viability and enhance tolerance of inflammatory insult, as evidenced by suppressing expression of CD40, translocation of NF-κB p65 subunit, phosphorylation of IκB-α, as well as the activity of IKK-β. In addition, downstream inflammatory cytokines modulated by NF-κB signaling were effectively down-regulated both in vivo and in vitro, as determined by immunohistochemistry and ELISA. In conclusion, these results indicate that GC possesses a beneficial effect against MI/R injury via inflammation inhibition that may involve suppression of CD40-NF-κB signal pathway and downstream inflammatory cytokines expression, which may offer an alternative medication for MI/R diseases.

A major chromatin regulator determines resistance of tumor cells to T cell-mediated killing

Many human cancers are resistant to immunotherapy, for reasons that are poorly understood. We used a genome-scale CRISPR-Cas9 screen to identify mechanisms of tumor cell resistance to killing by cytotoxic T cells, the central effectors of antitumor immunity. Inactivation of >100 genes-including Pbrm1, Arid2, and Brd7, which encode components of the PBAF form of the SWI/SNF chromatin remodeling complex-sensitized mouse B16F10 melanoma cells to killing by T cells. Loss of PBAF function increased tumor cell sensitivity to interferon-γ, resulting in enhanced secretion of chemokines that recruit effector T cells. Treatment-resistant tumors became responsive to immunotherapy when Pbrm1 was inactivated. In many human cancers, expression of PBRM1 and ARID2 inversely correlated with expression of T cell cytotoxicity genes, and Pbrm1-deficient murine melanomas were more strongly infiltrated by cytotoxic T cells.

The interplay of IKK, NF-κB and RIPK1 signaling in the regulation of cell death, tissue homeostasis and inflammation

Regulated cell death pathways have important functions in host defense and tissue homeostasis. Studies in genetic mouse models provided evidence that cell death could cause inflammation in different tissues. Inhibition of RIPK3-MLKL-dependent necroptosis by FADD and caspase-8 was identified as a key mechanism preventing inflammation in epithelial barriers. Moreover, the interplay between IKK/NF-κB and RIPK1 signaling was recognized as a critical determinant of tissue homeostasis and inflammation. NEMO was shown to regulate RIPK1 kinase activity-mediated apoptosis by NF-κB-dependent and -independent functions, which are critical for averting chronic tissue injury and inflammation in the intestine and the liver. In addition, RIPK1 was shown to exhibit kinase activity-independent functions that are essential for preventing cell death, maintaining tissue architecture and inhibiting inflammation. In the intestine, RIPK1 acts as a scaffold to prevent epithelial cell apoptosis and preserve tissue integrity. In the skin, RIPK1 functions via its RHIM to counteract ZBP1/DAI-dependent activation of RIPK3-MLKL-dependent necroptosis and inflammation. Collectively, these studies provided evidence that the regulation of cell death signaling plays an important role in the maintenance of tissue homeostasis, and suggested that cell death could be causally involved in the pathogenesis of inflammatory diseases.

Enzymatic Self-Assembly Confers Exceptionally Strong Synergism with NF-κB Targeting for Selective Necroptosis of Cancer Cells

As a promising molecular process for selectively inhibiting cancer cells without inducing acquired drug resistance, enzyme-instructed self-assembly (EISA) usually requires relatively high dosages. Despite its discovery 30 years ago, the translation of the knowledge about NF-κB signaling into clinic remains complicated due to the broad roles of NF-κB in cellular regulation. Here we show that integrating EISA and NF-κB targeting boosts the efficacy of EISA over an order of magnitude without compromising selectivity against cancer cells. That is, in situ enzymatic self-assembly of a tetrapeptide results in nanofibers, which hardly affect cell viability, but lead to inductive expression of tumor necrosis factor receptor 2 (TNFR2) and decreased expression of three key proteins at the upstream of NF-κB pathway in the cancer cells. Adding the inhibitors targeting NF-κB further decreases the expressions of those upstream proteins, which turns the otherwise innocuous nanofibers to being lethal to the cancer cells, likely causing necroptosis. As the first case of using supramolecular processes to enable synthetic lethality, this work illustrates a versatile approach to translate key regulatory circuits into promising therapeutic targets.

Modulating inflammation through the negative regulation of NF-κB signaling

Immune system activation is essential to thwart the invasion of pathogens and respond appropriately to tissue damage. However, uncontrolled inflammation can result in extensive collateral damage underlying a diverse range of auto-inflammatory, hyper-inflammatory, and neoplastic diseases. The NF-κB signaling pathway lies at the heart of the immune system and functions as a master regulator of gene transcription. Thus, this signaling cascade is heavily targeted by mechanisms designed to attenuate overzealous inflammation and promote resolution. Mechanisms associated with the negative regulation of NF-κB signaling are currently under intense investigation and have yet to be fully elucidated. Here, we provide an overview of mechanisms that negatively regulate NF-κB signaling through either attenuation of signal transduction, inhibition of posttranscriptional signaling, or interference with posttranslational modifications of key pathway components. While the regulators discussed for each group are far from comprehensive, they exemplify common mechanistic approaches that inhibit this critical biochemical signaling cascade. Despite their diversity, a commonality among these regulators is their selection of specific targets at key inflection points in the pathway, such as TNF-receptor-associated factor family members or essential kinases. A better understanding of these negative regulatory mechanisms will be essential to gain greater insight related to the maintenance of immune system homeostasis and inflammation resolution. These processes are vital elements of disease pathology and have important implications for targeted therapeutic strategies.

NF-κB in Oxidative Stress

The transcription factor nuclear factor-κB (NF-κB) modulates gene expression in diverse cellular processes such as innate immune response, embryogenesis and organ development, cell proliferation and apoptosis, and stress responses to a variety of noxious stimuli. When cellular production of reactive oxygen species (ROS) overwhelms its antioxidant capacity, it leads to a state of oxidative stress, which in turn contributes to the pathogenesis of several human diseases. Different models of oxidative stress have been studied to elucidate the effects of oxidant stress on NF-κB related activities. ROS can both activate and repress NF-κB signaling in a phase and context dependent manner. The NF-κB pathway can have both anti- and pro-oxidant roles in the setting of oxidative stress. In this review, we focus on role of oxidative stress on different mediators of the NF-κB pathway, and the role of NF-κB activation in the modulation of oxidative stress. A greater understanding of the complex interplay between the NF-κB signaling and oxidative stress may lead to the development of therapeutic strategies for the treatment of a myriad of human diseases for which oxidative stress has an etiologic role.

NF-κB in the crosshairs: Rethinking an old riddle

Constitutive NF-κB signalling has been implicated in the pathogenesis of most human malignancies and virtually all non-malignant pathologies. Accordingly, the NF-κB pathway has been aggressively pursued as an attractive therapeutic target for drug discovery. However, the severe on-target toxicities associated with systemic NF-κB inhibition have thus far precluded the development of a clinically useful, NF-κB-targeting medicine as a way to treat patients with either oncological or non-oncological diseases. This minireview discusses some of the more promising approaches currently being developed to circumvent the preclusive safety liabilities of global NF-κB blockade by selectively targeting pathogenic NF-κB signalling in cancer, while preserving the multiple physiological functions of NF-κB in host defence responses and tissue homeostasis.

B7-Homolog 4 Promotes Epithelial-Mesenchymal Transition and Invasion of Bladder Cancer Cells via Activation of Nuclear Factor-κB

B7-homolog 4 (B7-H4), a member of the B7 family of costimulatory molecules, has been reported to be upregulated in urothelial cell carcinoma. This study was conducted to explore the biological role of B7-H4 in the aggressiveness of bladder cancer and the associated molecular mechanism. We found that the mRNA and protein levels of B7-H4 were significantly greater in bladder cancer cell lines than in SV-HUC-1 (normal human urothelial cells). Overexpression of B7-H4 significantly promoted bladder cancer cell migration and invasion, whereas knockdown of B7-H4 exerted an opposite effect. However, the growth of bladder cancer cells was not altered by B7-H4 overexpression or knockdown. Overexpression of B7-H4 promoted epithelial–mesenchymal transition (EMT), as evidenced by decreased E-cadherin and increased vimentin expression. The EMT inducers Twist1 and Snail were upregulated by B7-H4 overexpression and downregulated by B7-H4 silencing. Mechanistically, overexpression of B7-H4 induced the activation of NF-κB signaling. Pharmacological inhibition of NF-κB partially prevented B7-H4-mediated bladder cancer cell invasion. Taken together, B7-H4/NF-κB signaling is involved in the EMT and invasion of bladder cancer cells and represents a new candidate target for the treatment of bladder cancer.

Differential Regulation of NF-κB and Nrf2 by Bojungikki-Tang Is Associated with Suppressing Lung Inflammation

Bojungikki-tang (BT), an Asian herbal remedy, has been prescribed to increase the vitality of debilitated patients. Since a compromised, weakened vitality often leads to illness, BT has been widely used to treat various diseases. However, little is known about the mechanism by which BT exerts its effect. Given that BT ameliorates inflammatory pulmonary diseases including acute lung injury (ALI), we investigated whether BT regulates the function of key inflammatory factors such as NF-κB and Nrf2, contributing to suppressing inflammation. Results show that BT interrupted the nuclear localization of NF-κB and suppressed the expression of the NF-κB-dependent genes in RAW 264.7 cells. In similar experiments, BT induced the nuclear localization of Nrf2 and the expression of the Nrf2-dependent genes. In a lipopolysaccharide-induced ALI mouse model, a single intratracheal administration of BT to mouse lungs ameliorated alveolar structure and suppressed the expression of proinflammatory cytokine genes and neutrophil infiltration to mouse lungs. Therefore, our findings suggest that suppression of NF-κB and activation of Nrf2, by which BT suppresses inflammation, are ways for BT to exert its effect.

Modeling the therapeutic efficacy of NFκB synthetic decoy oligodeoxynucleotides (ODNs)

BACKGROUND

Transfection of NF κB synthetic decoy Oligodeoxynucleotides (ODNs) has been proposed as a promising therapeutic strategy for a variety of diseases arising from constitutive activation of the eukaryotic transcription factor NF κB. The decoy approach faces some limitations under physiological conditions notably nuclease-induced degradation.

RESULTS

In this work, we show how a systems pharmacology model of NF κB regulatory networks displaying oscillatory temporal dynamics, can be used to predict quantitatively the dependence of therapeutic efficacy of NF κB synthetic decoy ODNs on dose, unbinding kinetic rates and nuclease-induced degradation rates. Both deterministic mass action simulations and stochastic simulations of the systems biology model show that the therapeutic efficacy of synthetic decoy ODNs is inversely correlated with unbinding kinetic rates, nuclease-induced degradation rates and molecular stripping rates, but is positively correlated with dose. We show that the temporal coherence of the stochastic dynamics of NF κB regulatory networks is most sensitive to adding NF κB synthetic decoy ODNs having unbinding time-scales that are in-resonance with the time-scale of the limit cycle of the network.

CONCLUSIONS

The pharmacokinetics/pharmacodynamics (PK/PD) predicted by the systems-level model should provide quantitative guidance for in-depth translational research of optimizing the thermodynamics/kinetic properties of synthetic decoy ODNs.

IKKβ is a β-catenin kinase that regulates mesenchymal stem cell differentiation

Mesenchymal stem cells (MSCs) can give rise to both adipocytes and osteoblasts, but the molecular mechanisms underlying MSC fate determination remain poorly understood. IκB kinase β (IKKβ), a central coordinator of inflammation and immune responses through activation of NF-κB, has been implicated as a critical molecular link between obesity and metabolic disorders. Here, we show that IKKβ can reciprocally regulate adipocyte and osteoblast differentiation of murine and human MSCs through an NF-κB-independent mechanism. IKKβ is a β-catenin kinase that phosphorylates the conserved degron motif of β-catenin to prime it for β-TrCP-mediated ubiquitination and degradation, thereby increasing adipogenesis and inhibiting osteogenesis in MSCs. Animal studies demonstrated that deficiency of IKKβ in BM mesenchymal stromal cells increased bone mass and decreased BM adipocyte formation in adult mice. In humans, IKKβ expression in adipose tissue was also positively associated with increased adiposity and elevated β-catenin phosphorylation. These findings suggest IKKβ as a key molecular switch that regulates MSC fate, and they provide potentially novel mechanistic insights into the understanding of the cross-regulation between the evolutionarily conserved IKKβ and Wnt/β-catenin signaling pathways. The IKKβ-Wnt axis we uncovered may also have important implications for development, homeostasis, and disease pathogenesis.

Effects of a novel microtubule-depolymerizer on pro-inflammatory signaling in RAW264.7 macrophages

The Nuclear Factor-kappa B (NF-κB) pathway is vital for immune system regulation and pro-inflammatory signaling. Many inflammatory disorders and diseases, including cancer, are linked to dysregulation of NF-κB signaling. When macrophages recognize the presence of a pathogen, the signaling pathway is activated, resulting in the nuclear translocation of the transcription factor, NF-κB, to turn on pro-inflammatory genes. Here, we demonstrate the effects of a novel microtubule depolymerizer, NT-07-16, a polysubstituted pyrrole compound, on this process. Treatment with NT-07-16 decreased the production of pro-inflammatory cytokines in RAW264.7 mouse macrophages. It appears that the reduction in pro-inflammatory mediators produced by the macrophages after exposure to NT-07-16 may be due to activities upstream of the translocation of NF-κB into the nucleus. NF-κB translocation occurs after its inhibitory protein, IκB-α is phosphorylated which signals for its degradation releasing NF-κB so it is free to move into the nucleus. Previous studies from other laboratories indicate that these processes are associated with the microtubule network. Our results show that exposure to the microtubule-depolymerizer, NT-07-16 reduces the phosphorylation of IκB-α and also decreases the association of NF-κB with tubulin which may affect the ability of NF-κB to translocate into the nucleus. Therefore, the anti-inflammatory activity of NT-07-16 may be explained, at least in part, by alterations in these steps in the NF-κB signaling pathway leading to less NF-κB entering the nucleus and reducing the production of pro-inflammatory mediators by the activated macrophages.

Prolactin inhibits the progression of intervertebral disc degeneration through inactivation of the NF-κB pathway in rats

Intervertebral disc degeneration (IVDD) is one of the key predisposing factors for low back pain. Although the exact mechanism remains unclear, inflammatory response and nucleus pulposus (NP) apoptosis are known to play important roles in this process. Prolactin protects against inflammation-associated chondrocyte apoptosis in arthritis. Based on prior studies, we hypothesized that prolactin might have therapeutic effects on IVDD by inhibiting the apoptosis of degenerative human disc NP cells. An experimental model of IVDD was established in 3-month-old Sprague-Dawley rats by submitting them to percutaneous disc puncture with a 20-gauge needle on levels 7–8 and 8–9 of the coccygeal vertebrae. Then the rats were injected with 20 or 200 ng prolactin on a weekly basis. Radiologic and histologic analyses were performed on days 4, 7, 14, and 28. The expression of prolactin and its receptor was analyzed in human tissue obtained from symptomatic patients undergoing microencoscopy discectomy, or from scoliosis patients undergoing deformity correction surgery. The results showed that intradiscal injection of prolactin maintained disc height and the mean signal intensity of the punctured disc. Histological analysis indicated that prolactin treatment significantly retained the complete structure of the NP and annulus fibrosus compared with the vehicle group. In addition, more collagen II, but fewer collagen I-containing tissues were detected in the prolactin treatment groups compared to the vehicle group. Moreover, low levels of tumor necrosis factor-α, interleukin-1β, cleaved-caspase 3, and TUNEL staining were observed in the prolactin treatment groups. We also demonstrated that prolactin impaired puncture-induced inflammation and cell apoptosis by downregulating activation of the NF-κB pathway. The degenerated NP tissues from patients had decreased expression of prolactin and its receptor, whereas expression was increased in the NP tissues removed from scoliosis patients. These results suggest that prolactin may be a novel therapeutic target for the treatment of IVDD.

The NALP3 inflammasome is required for collagen synthesis via the NF‑κB pathway

The NALP3 inflammasome interacts with various immune and cell metabolic pathways and may participate in pulmonary fibrosis. However, little is known on its regulatory mechanism with respect to collagen synthesis. The objective of the present study was to investigate whether NALP3 inflammasome activation is involved in H2O2‑mediated collagen synthesis, in addition to examining the possible cell signaling mechanisms underlying this effect. It was demonstrated that the NF‑κB signaling pathway was activated under conditions of H2O2‑mediated oxidative stress in NIH‑3T3 mouse embryonic fibroblasts. H2O2‑exposed fibroblasts exhibited activated NALP3 inflammasomes via increased NALP3, apoptosis‑associated Speck‑like protein and caspase‑1 expression and the secretion of interleukin‑1β. H2O2 also elevated α‑SMA and type I collagen expression. In vitro silencing of NALP3 attenuated the degradation of IκBα and decreased the synthesis of type I collagen. Furthermore, the NALP3 inflammasome was found to be activated in bleomycin‑induced pulmonary fibrosis in mice, and this activation was relieved by a nuclear factor (NF)‑κB inhibitor. Taken together, these findings indicate that the NALP3 inflammasome is involved in H2O2‑induced type I collagen synthesis, which is mediated by the NF‑κB signaling pathway. Additionally, the NALP3 inflammasome contributes to the development of bleomycin‑induced pulmonary fibrosis.

TRAF3 regulation of inhibitory signaling pathways in B and T lymphocytes by kinase and phosphatase localization

This brief review presents current understanding of how the signaling adapter protein TRAF3 can both induce and block inhibitory signaling pathways in B and T lymphocytes, via association with kinases and phosphatases, and subsequent regulation of their localization within the cell. In B lymphocytes, signaling through the interleukin 6 receptor (IL-6R) induces association of TRAF3 with IL-6R-associated JAK1, to which TRAF3 recruits the phosphatase PTPN22 (protein tyrosine phosphatase number 22) to dephosphorylate JAK1 and STAT3, inhibiting IL-6R signaling. An important biological consequence of this inhibition is restraining the size of the plasma cell compartment, as their differentiation is IL-6 dependent. Similarly, in T lymphocytes, interleukin 2 receptor (IL-2R) signaling recruits TRAF3, which in turn recruits the phosphatase TCPTP (T cell protein tyrosine phosphatase) to dephosphorylate JAK3. The resulting inhibition of IL-2R signaling limits the IL-2-dependent size of the T regulatory cell (Treg) compartment. TRAF3 also inhibits type 1 IFN receptor (IFNαR) signaling to T cells by this mechanism, restraining expression of IFN-stimulated gene expression. In contrast, TRAF3 association with two inhibitors of TCR signaling, C-terminal Src kinase (Csk) and PTPN22, promotes their localization to the cytoplasm, away from the membrane TCR complex. TRAF3 thus enhances TCR signaling and downstream T cell activation. Implications are discussed for these regulatory roles of TRAF3 in lymphocytes, as well as potential future directions.

Redox regulation of microRNAs in cancer

Dysregulation of microRNAs (miRNAs) has long been implicated in tumorigenesis, whereas the underlying mechanisms remain largely unknown. Oxidative stress is a hallmark of cancer that involved in multiple pathophysiological processes, including the aberrant regulation of miRNAs. Compelling evidences have implied complicated interplay between reactive oxygen species (ROS) and miRNAs. Indeed, ROS induces carcinogenesis through either reducing or increasing the miRNA level, leading to the activation of oncogenes or silence of tumor suppressors, respectively. In turn, miRNAs target ROS productive genes or antioxidant responsive elements to affect cellular redox balance, which contributes to establishing a microenvironment favoring cancer cell growth and metastasis. Both miRNAs and ROS have been identified as potential biomarkers and therapeutic targets in human malignancies, and comprehensive understanding of the molecular events herein will facilitate the development of novel cancer therapeutic strategies.

Cyclin-Dependent Kinase 8: A New Hope in Targeted Cancer Therapy?

Cyclin-dependent kinase 8 (CDK8) plays a vital role in regulating transcription either through its association with the Mediator complex or by phosphorylating transcription factors. Myriads of genetic and biochemical studies have established CDK8 as a key oncogenic driver in many cancers. Specifically, CDK8-mediated activation of oncogenic Wnt-β-catenin signaling, transcription of estrogen-inducible genes, and suppression of super enhancer-associated genes contributes to oncogenesis in colorectal, breast, and hematological malignancies, respectively. However, while most research supports the role of CDK8 as an oncogene, other work has raised the possibility of its contrary function. The diverse biological functions of CDK8 and its seemingly context-specific roles in different types of cancers have spurred a great amount of interest and perhaps an even greater amount of controversy in the development of CDK8 inhibitors as potential cancer therapeutic agents. Herein, we review the latest landscape of CDK8 biology and its involvement in carcinogenesis. We dissect current efforts in discovering CDK8 inhibitors and attempt to provide an outlook at the future of CDK8-targeted cancer therapies.

Targeting oncogenic transcription factors by polyphenols: A novel approach for cancer therapy

Inflammation is one of the major causative factor of cancer and chronic inflammation is involved in all the major steps of cancer initiation, progression metastasis and drug resistance. The molecular mechanism of inflammation driven cancer is the complex interplay between oncogenic and tumor suppressive transcription factors which include FOXM1, NF-kB, STAT3, Wnt/β- Catenin, HIF-1α, NRF2, androgen and estrogen receptors. Several products derived from natural sources modulate the expression and activity of multiple transcription factors in various tumor models as evident from studies conducted in cell lines, pre-clinical models and clinical samples. Further combination of these natural products along with currently approved cancer therapies added an additional advantage and they considered as promising targets for prevention and treatment of inflammation and cancer. In this review we discuss the application of multi-targeting natural products by analyzing the literature and future directions for their plausible applications in drug discovery.

Role of nuclear factor κB in multiple sclerosis and experimental autoimmune encephalomyelitis

The transcription factor nuclear factor κB (NF-κB) plays major roles in inflammatory diseases through regulation of inflammation and cell viability. Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system (CNS). It has been shown that NF-κB is activated in multiple cell types in the CNS of MS patients, including T cells, microglia/macrophages, astrocytes, oligodendrocytes, and neurons. Interestingly, data from animal model studies, particularly studies of experimental autoimmune encephalomyelitis, have suggested that NF-κB activation in these individual cell types has distinct effects on the development of MS. In this review, we will cover the current literature on NF-κB and the evidence for its role in the development of MS and its animal model experimental autoimmune encephalomyelitis.

Nuclear Factor-kappaB in Autoimmunity: Man and Mouse

NF-κB (nuclear factor-kappa B) is a transcription complex crucial for host defense mediated by innate and adaptive immunity, where canonical NF-κB signaling, mediated by nuclear translocation of RelA, c-Rel, and p50, is important for immune cell activation, differentiation, and survival. Non-canonical signaling mediated by nuclear translocation of p52 and RelB contributes to lymphocyte maturation and survival and is also crucial for lymphoid organogenesis. We outline NF-κB signaling and regulation, then summarize important molecular contributions of NF-κB to mechanisms of self-tolerance. We relate these mechanisms to autoimmune phenotypes described in what is now a substantial catalog of immune defects conferred by mutations in NF-κB pathways in mouse models. Finally, we describe Mendelian autoimmune syndromes arising from human NF-κB mutations, and speculate on implications for understanding sporadic autoimmune disease.