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Management of clinically aggressive meningiomas is a considerable challenge. PD-L1 induced immune suppression has increasingly gained attention in clinical management of cancer; however, to date, the clinical significance and regulatory mechanisms of PD-L1 in meningioma is not yet fully characterized. We sought to characterize PD-L1 expression in meningioma and elucidate its regulatory mechanisms. Immunohistochemical staining of PD-L1 expression in meningiomas showed 43% positivity in both tumor and immune cells and we observed intra and inter tumoral heterogeneity. Univariate and multivariate analyses confirmed that PD-L1 protein expression is an independent prognostic marker for worse recurrence free survival in meningioma. Furthermore, our transcriptomic analysis revealed a strong association between PD-L1 expression and that of NFKB2 and carbonic anhydrase 9 (CA9). We also demonstrated that both of these markers, when co-expressed with PD-L1, predict tumor progression. Our studies on several meningioma cell lines cultured in hypoxic conditions validated the association of CA9 and PD-L1 expression. Here we show the clinical significance of PD-L1 in meningioma as a marker that can predict tumor recurrence. We also show an association PD-L1 expression with NFKB2 expression and its induction under hypoxic conditions. These findings may open new avenues of molecular investigation in pathogenesis of meningioma.

In murine bone-marrow stromal microenvironment cells and in human multipotent mesenchymal stromal cells (MMSCs), proinflammatory cytokine interleukin-1 beta (IL-1β) serves as a growth factor. In murine bone tissue, IL-1β expression increases in vivo after irradiation. Here, we have presented our evaluation of the effects of exogenous IL-1β on the expression of NF-kB transcription factors in human MMSCs and stromal layer cells of murine long-term bone marrow cultures (LTBMCs). The cytokine signaling pathway was also activated in murine LTBMC by braking electron radiation in doses of 3-12 Gy. The level of expression of genes that code for IL-1β, IL-1β type-I receptor and NF-kB and IKK protein families have been studied at different time points post exposure. In both human and murine stromal cells, exogenous IL-1β led to an increase in the level of expression of its own gene, while levels of expression of NF-kB and IKK gene families were not substantially changed. Nevertheless, in human cells, a significant correlation between levels of expression of IL-1β and all NF-kB family genes was detected. It points to a similarity in IL-1β signal pathways in mesenchymal and hematopoietic cells, where the posttranslational modifications of NF-kB transcription factors play a major role. The irradiation of murine LTBMC resulted in a transient increase in the expression of genes that code NF-kB transcription factors and IL-1β. These results indicate an important role of Rel, Rela, Relb, and Nfkb2 genes in the induction of IL-1β signal pathway in murine stromal cells. An increase in IL-1β expression after the irradiation of stromal cells may be related to both the induction of inflammation due to massive cell death and to a profound stimulation of the expression of this proinflammatory cytokine expression.

Enhancer of Zeste homologue 2 (EZH2) belongs to the polycomb repressive complex 2 and catalyzes the methylation of histone H3 lysine 27. These pivotal epigenetic marks are altered in many cancers, including melanoma, as a result of EZH2 overexpression. Here, we show that the non-canonical-NF-kB pathway accounts for most of the NF-kB activity in melanoma cells, in contrast to non-cancer cells. We identify the non-canonical-NF-kB pathway as a key regulator of EZH2 expression in melanoma. We show a striking correlation between NF-kB2 and EZH2 expression in human melanoma metastases. We demonstrate that inhibition of the non-canonical NF-kB pathway by targeting NF-kB2/p52 or the upstream kinase NIK restores the senescence program in melanoma cells through the decrease of EZH2. On the contrary, the overexpression of NF-kB2/p52 in normal human melanocytes prevents stress- and oncogene-induced senescence. Finally, we show in mouse models that the inhibition of the non-canonical NF-kB pathway restores senescence and induces a dramatic reduction in tumor growth compared with controls, thus providing potential drug targets for the re-induction of senescence in melanoma and other cancers where EZH2 is overexpressed.

Objective: Nuclear factor kappa B (NF-κB) is an important transcription factor in cancer and NF-κB activation has been seen in angiogenesis, tumor progression, and metastasis. Relationships between specific NF-κB gene networks, leukemogenesis, and radiation exposure are still unknown. Our aim was to study the expression levels of the NF-κB1, NF-κB2, and Rel genes in hematological malignancies in the post-Chernobyl period., Materials and Methods: We analyzed gene expression levels of NF-κB1, NF-κB2, and Rel in 49 B-cell chronic lymphocytic leukemia, 8 B-cell non-Hodgkin's lymphoma, 3 acute myeloid leukemia, 3 chronic myeloid leukemia, 2 hairy cell leukemia, 2 myelodysplastic syndrome, and 2 T-cell large granular lymphocytic leukemia patients using real-time polymerase chain reaction., Results: Expression levels of NF-κB1, NF-κB2, and Rel genes were found to be deregulated., Conclusion: These results could be accepted as specific gene traces to radiation-induced leukemia or as potential candidates for new diagnostic biomarker studies. Larger experiments and non-exposed control malignant cell populations are needed to clarify these suggestions.

Although numerous studies have demonstrated a critical role for canonical NF-κB signaling in inflammation and disease, the function of the noncanonical NF-κB pathway remains ill-defined. In lung tissue from patients with acute respiratory distress syndrome, we identified increased expression of the noncanonical pathway component p100/p52. To investigate the effects of p52 expression in vivo, we generated a novel transgenic mouse model with inducible expression of p52 in Clara cell secretory protein-expressing airway epithelial cells. Although p52 overexpression alone did not cause significant inflammation, p52 overexpression caused increased lung inflammation, injury, and mortality following intratracheal delivery of Escherichia coli LPS. No differences in cytokine/chemokine expression were measured between p52-overexpressing mice and controls, but increased apoptosis of Clara cell secretory protein-positive airway epithelial cells was observed in transgenic mice after LPS stimulation. In vitro studies in lung epithelial cells showed that p52 overexpression reduced cell survival and increased the expression of several proapoptotic genes during cellular stress. Collectively, these studies demonstrate a novel role for p52 in cell survival/apoptosis of airway epithelial cells and implicate noncanonical NF-κB signaling in the pathogenesis of acute respiratory distress syndrome., (Copyright © 2016 by The American Association of Immunologists, Inc.)

Overexpression of the antiviral DNA cytosine deaminase APOBEC3B has been linked to somatic mutagenesis in many cancers. Human papillomavirus infection accounts for APOBEC3B upregulation in cervical and head/neck cancers, but the mechanisms underlying nonviral malignancies are unclear. In this study, we investigated the signal transduction pathways responsible for APOBEC3B upregulation. Activation of protein kinase C (PKC) by the diacylglycerol mimic phorbol-myristic acid resulted in specific and dose-responsive increases in APOBEC3B expression and activity, which could then be strongly suppressed by PKC or NF-κB inhibition. PKC activation caused the recruitment of RELB, but not RELA, to the APOBEC3B promoter, implicating noncanonical NF-κB signaling. Notably, PKC was required for APOBEC3B upregulation in cancer cell lines derived from multiple tumor types. By revealing how APOBEC3B is upregulated in many cancers, our findings suggest that PKC and NF-κB inhibitors may be repositioned to suppress cancer mutagenesis, dampen tumor evolution, and decrease the probability of adverse outcomes, such as drug resistance and metastasis., (©2015 American Association for Cancer Research.)

Signaling by hormonal vitamin D, 1,25-dihydroxyvitamin D (1,25D) has attracted increasing interest because of its non-classical actions, particularly its putative anticancer properties and its role in controlling immune system function. Notably, the hormone-bound vitamin D receptor (VDR) suppresses signaling by pro-inflammatory NF-κB transcription factors, although the underlying mechanisms have remained elusive. Recently, the VDR was shown to enhance the turnover of the oncogenic transcription factor cMYC mediated by the E3 ligase and tumor suppressor FBW7. As FBW7 also controls the turnover of the p100 (NF-κB2) subunit of the family, we determined whether the 1,25D enhanced FBW7-dependent turnover of NF-κB subunits p100, p105 (NF-κB1) and p65 (RELA). Protein levels of all three subunits declined markedly in the presence of 1,25D in multiple cell lines in the absence of substantial changes in mRNA expression. The VDR coimmunoprecipitated with all three subunits, and 1,25D treatment accelerated subunit turnover in cycloheximide-treated cells. Importantly, we observed an association of FBW7 with p105 and p65, as well as p100, and knockdown of FBW7 eliminated 1,25D-dependent subunit turnover. Moreover, expression of NF-κB target genes was elevated in FBW7-depleted cells. These results reveal that 1,25D signaling suppresses NF-κB function by enhancing FBW7-dependent subunit turnover.

NF-κB-inducing kinase (NIK) is a primary regulator of the noncanonical NF-κB signaling pathway, which plays a vital role downstream of BAFF, CD40L, lymphotoxin, and other inflammatory mediators. Germline deletion or inactivation of NIK in mice results in the defective development of B cells and secondary lymphoid organs, but the role of NIK in adult animals has not been studied. To address this, we generated mice containing a conditional allele of NIK. Deletion of NIK in adult mice results in decreases in B cell populations in lymph nodes and spleen, similar to what is observed upon blockade of BAFF. Consistent with this, B cells from mice in which NIK is acutely deleted fail to respond to BAFF stimulation in vitro and in vivo. In addition, mice with induced NIK deletion exhibit a significant decrease in germinal center B cells and serum IgA, which is indicative of roles for NIK in additional pathways beyond BAFF signaling. Our conditional NIK-knockout mice may be broadly useful for assessing the postdevelopmental and cell-specific roles of NIK and the noncanonical NF-κB pathway in mice., (Copyright © 2015 by The American Association of Immunologists, Inc.)

Endotoxin tolerance (ET) is a state of reduced responsiveness to endotoxin stimulation after a primary bacterial insult. This phenomenon has been described in several pathologies, including sepsis, in which an endotoxin challenge results in reduced cytokine production. In this study, we show that the NFκ L chain enhancer of activated B cells 2 (NFκB2)/p100 was overexpressed and accumulated in a well-established in vitro human monocyte model of ET. The p100 accumulation in these cells inversely correlated with the inflammatory response after LPS stimulation. Knocking down NFκB2/p100 using small interfering RNA in human monocytes further indicated that p100 expression is a crucial factor in the progression of ET. The monocytes derived from patients with sepsis had high levels of p100, and a downregulation of NFκB2/p100 in these septic monocytes reversed their ET status., (Copyright © 2014 by The American Association of Immunologists, Inc.)

Effects of blocking toll-like receptor-2 (TLR-2) on the survival of Staphylococcus aureus (S. aureus) and cytokine production in peritoneal macrophages of Swiss albino mice were analysed. Macrophages were infected with S. aureus in the presence and absence of anti-TLR-2 antibody. Tumour necrosis factor-α (TNF-α) interleukin-6 (IL-6), interferon-gamma (IFN-γ), interleukin-1β (IL-1β), interleukin-12 (IL-12) and interleukin-10 (IL-10) concentrations were measured. Expressions of TLR-2, NF-κB, MyD 88 were analysed by Western Blot. Expression of TLR-2 was increased in S. aureus-infected macrophages with respect to control and was MyD 88 independent. TLR2 blocking significantly reduced TNF-α, IL-6, IL-1β and IL-10 and increased IFN-γ and IL-12 production. Decreased catalase activity and increased superoxide dismutase (SOD) by S. aureus with concomitant increase in H2 O2 and nitric oxide (NO) were observed in the case of prior TLR-2 blocking. To understand whether catalase contributing in the intracellular survival, was of bacterial origin or not, 3-amino, 1, 2, 4-triazole (ATZ) was used to inhibit specifically macrophage-derived catalase. Catalase enzyme activity from the whole staphylococcal cells in the presence of ATZ suggested that the released catalase were of extracellular origin. From the intracellular survival assay, it was evident that pretreatment of macrophages with ATZ reduces the bacterial burden in macrophages when infected with the recovered bacteria only from the anti-TLR-2 antibody-treated macrophages after phagocytosis. Catalase protein expression from the whole staphylococcal cells recovered after phagocytosis also indicated the catalase release from S. aureus. Capturing of S. aureus via TLR-2 induces inflammatory reactions through activation of NF-κB-signalling pathways which was MyD88-independent., (© 2014 John Wiley & Sons Ltd.)

Decitabine, a demethylating drug, is the first-line treatment for myelodysplastic syndromes and gains better overall survival, which is based on epigenetic mechanism. Activated by promoter demethylation, melanoma-associated antigens-A (MAGE-A), cancer-testis antigens are attractive targets for immunotherapy. Our purpose was to investigate whether decitabine could show anti-tumor effects for esophageal cancer and explore its mechanism. In addition, we aimed to examine its modulation for most MAGE-A members. The results showed the baseline expression were MAGE-A2, -3,-9, and -10 in Eca109 cells and decitabine (0.5 μM) could induce MAGE-A8 and -A4 whereas reduce MAGE-A9 and -A10. Moreover, decitabine (0.5 μM) inhibited cell proliferation, migration and invasive ability by 15%, 34% and 47.2%, respectively and decreased expressions of NF-κB2 and MMP2. Our results demonstrated that low-dose decitabine induced the expression of MAGE-A8 and -A4, and inhibited cell invasion through decreasing expression of MMP2 and NF-κB2, which provides possibilities for combing decitabine with immunotherapy targeting MAGE-A to treat advanced esophageal squamous cell carcinoma., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Fucoxanthin is a carotenoid present in the chloroplasts of brown seaweeds. When ingested, it is metabolized mainly to fucoxanthinol in the gastrointestinal tract by digestive enzymes. These compounds have been shown to have many beneficial health effects. The present study was designed to evaluate the molecular mechanisms of action of fucoxanthin and/or of its metabolite fucoxanthinol against viability of estrogen-sensitive MCF-7 and estrogen-resistant MDA-MB-231 breast cancer cell lines. Fucoxanthin and fucoxanthinol reduced the viability of MCF-7 and MDA-MB-231 cells in dose- and time-dependent manners as a result of increased apoptosis. Furthermore, fucoxanthinol-induced apoptosis was more potent than that of fucoxanthin and correlated, for MDA-MB-231 cells, with inhibitory actions on members of the NF-κB pathway p65, p50, RelB, and p52. Being overexpressed and regulated by NF-κB in different types of cancers, the transcription factor SOX9 was also decreased at the nuclear level by fucoxanthin and fucoxanthinol in MDA-MB-231. Taken together, the current results suggest that fucoxanthinol and fucoxanthin could be potentially effective for the treatment and/or prevention of different types of cancers, including breast cancer.

HMGB1 is a chromatin architectural protein that is released by dead or damaged cells at sites of tissue injury. Extracellular HMGB1 functions as a proinflammatory cytokine and chemoattractant for immune effector and progenitor cells. Previously, we have shown that the inhibitor of NF-κB kinase (IKK)β- and IKKα-dependent NF-κB signaling pathways are simultaneously required for cell migration to HMGB1. The IKKβ-dependent canonical pathway is needed to maintain expression of receptor for advanced glycation end products, the ubiquitously expressed receptor for HMGB1, but the target of the IKKα non-canonical pathway was not known. In this study, we show that the IKKα-dependent p52/RelB noncanonical pathway is critical to sustain CXCL12/SDF1 production in order for cells to migrate toward HMGB1. Using both mouse bone marrow-derived macrophages and mouse embryo fibroblasts (MEFs), it was observed that neutralization of CXCL12 by a CXCL12 mAb completely eliminated chemotaxis to HMGB1. In addition, the HMGB1 migration defect of IKKα KO and p52 KO cells could be rescued by adding recombinant CXCL12 to cells. Moreover, p52 KO MEFs stably transduced with a GFP retroviral vector that enforces physiologic expression of CXCL12 also showed near normal migration toward HMGB1. Finally, both AMD3100, a specific antagonist of CXCL12's G protein-coupled receptor CXCR4, and an anti-CXCR4 Ab blocked HMGB1 chemotactic responses. These results indicate that HMGB1-CXCL12 interplay drives cell migration toward HMGB1 by engaging receptors of both chemoattractants. This novel requirement for a second receptor-ligand pair enhances our understanding of the molecular mechanisms regulating HMGB1-dependent cell recruitment to sites of tissue injury.

Activation of nuclear factor-kappa B (NF-kappaB) signaling is considered an important mechanism in the development of prostate cancers. A recent study revealed that IkappaB kinase epsilon (IKKepsilon), an activator of NF-kappaB, was overexpressed in breast cancers and acted as an oncogene. Expression of NF-kappaB members has been reported in prostate cancer tissues, but expression of IKKepsilon has not yet been studied in prostate cancers. In this study, we attempted to explore as to whether expressions of IKKepsilon and NF-kappaB members p50/105, p52/p100 and RelA are altered in prostate cancers. We analyzed the expression of IKKepsilon, p50/105, p52/p100 and RelA in 107 prostate adenocarcinoma tissues by immunohistochemistry using a tissue microarray (TMA) method. In the TMA, IKKepsilon is expressed in basal cells, but not in alveolar cells in normal prostate glands. IKKepsilon is expressed in 60.0% of prostate intraepithelial neoplasm (PIN) and 70.1% of the prostate cancers in the cytoplasm. Nuclear immunostainings of NF-kappaB members p50/105, p52/p100 and RelA, which are considered activation of NF-kappaB signaling, were observed respectively in 28.0%, 18.7% and 37.4% of the cancers. Nuclear staining was detected neither in normal alveolar cells nor in PIN. However, none of the expression of p50/105 nor p52/p100 nor RelA nor IKKepsilon was associated with pathologic characteristics, including size of the cancers, age, Gleason score and stage. The increased cytoplasmic expression of IKKepsilon as well as the increased nuclear expressions of p50/105, p52/p100 and RelA in the prostate cancers compared to normal alveolar cells suggested that overexpression of these proteins may be related to activation of the NF-kappaB pathway and might play a role in tumorigenesis of prostate cancers.

Viral infections induce signaling pathways in mammalian cells that stimulate innate immune responses and affect cellular processes, such as apoptosis, mitosis, and differentiation. Here, we report that the ribosomal protein S6 kinase alpha 3 (RSK2), which is activated through the "classical" mitogen-activated protein kinase pathway, plays a role in innate immune responses to influenza virus infection. RSK2 functions in the regulation of cell growth and differentiation but was not known to play a role in the cellular antiviral response. We have found that knockdown of RSK2 enhanced viral polymerase activity and growth of influenza viruses. Influenza virus infection stimulates NK-kappaB- and beta interferon-dependent promoters. This stimulation was reduced in RSK2 knockdown cells, suggesting that RSK2 executes its effect through innate immune response pathways. Furthermore, RSK2 knockdown suppressed influenza virus-induced phosphorylation of the double-stranded RNA-activated protein kinase PKR, a known antiviral protein. These findings establish a role for RSK2 in the cellular antiviral response.

Normal development of the immune system requires regulated processing of NF-kappaB2 p100 to p52, which activates NF-kappaB2 signaling. Constitutive production of p52 has been suggested as a major mechanism underlying lymphomagenesis induced by NF-kappaB2 mutations, which occur recurrently in a variety of human lymphoid malignancies. To test the hypothesis, we generated transgenic mice with targeted expression of p52 in lymphocytes. In contrast to their counterparts expressing the tumor-derived NF-kappaB2 mutant p80HT, which develop predominantly B cell tumors, p52 transgenic mice are not prone to lymphomagenesis. However, they are predisposed to inflammatory autoimmune disease characterized by multiorgan infiltration of activated lymphocytes, high levels of autoantibodies in the serum, and immune complex glomerulonephritis. p52, but not p80HT, represses Bim expression, leading to defects in apoptotic processes critical for elimination of autoreactive lymphocytes and control of immune response. These findings reveal distinct signaling pathways for actions of NF-kappaB2 mutants and p52 and suggest a causal role for sustained NF-kappaB2 activation in the pathogenesis of autoimmunity.

In mice, acquisition of Ly49 receptors characterizes one of the developmental stages of NK cells. We previously described a novel Ly49 promoter, Pro1, involved in Ly49 gene regulation in immature NK cells. Pro1 transcriptional activity requires a NF-kappaB binding site; however, only NF-kappaB/p50 binding to this element was observed. Cotransfection of NF-kappaB/p65 with Ly49g Pro1 in LNK cells induced a decrease in the transcriptional activity of the core promoter. Moreover, decreasing NF-kappaB/p65 protein expression by RNA interference increases Pro1 transcriptional activity. A high rate of NF-kappaB/p65 degradation in LNK cells correlates with Pro1 activity, since treatment with the proteasome inhibitor MG132 increased levels of NF-kappaB/p65 protein and decreased Pro1 activity. In addition, analysis of the Ly49 repertoire in NF-kappaB/p50 null mice reveals a decrease in the proportion of NK cells expressing a given Ly49 molecule. The defect in Ly49 expression is observed in the bone marrow and the spleen with a similar altered pattern of developmental stages in each tissue. The frequency of Ly49 expression in NF-kappaB/p52 null mice is slightly increased, indicating the specific role of NF-kappaB/p50 in Ly49 gene activation. These results suggest that NF-kappaB p50/p65 plays a major role in the initiation of Ly49 gene expression in NK cells.

Overexpression of mutant p53 is a common theme in tumors, suggesting a selective pressure for p53 mutation in cancer development and progression. To determine how mutant p53 expression may lead to survival advantage in human cancer cells, we generated stable cell lines expressing p53 mutants p53-R175H, -R273H, and -D281G by use of p53-null human H1299 (lung carcinoma) cells. Compared to vector-transfected cells, H1299 cells expressing mutant p53 showed a survival advantage when treated with etoposide, a common chemotherapeutic agent; however, cells expressing the transactivation-deficient triple mutant p53-D281G (L22Q/W23S) had significantly lower resistance to etoposide. Gene expression profiling of cells expressing transcriptionally active mutant p53 proteins revealed the striking pattern that all three p53 mutants induced expression of approximately 100 genes involved in cell growth, survival, and adhesion. The gene NF-kappaB2 is a prominent member of this group, whose overexpression in H1299 cells also leads to chemoresistance. Treatment of H1299 cells expressing p53-R175H with small interfering RNA specific for NF-kappaB2 made these cells more sensitive to etoposide. We have also observed activation of the NF-kappaB2 pathway in mutant p53-expressing cells. Thus, one possible pathway through which mutants of p53 may induce loss of drug sensitivity is via the NF-kappaB2 pathway.