NFkappaB1/p50 is not required for tumor necrosis factor-stimulated growth of primary mammary epithelial cells: implications for NFkappaB2/p52 and RelB

LTBP2 regulates cisplatin resistance in GC cells via activation of the NF-κB2/BCL3 pathway

Gastric cancer (GC) often develops resistance to cisplatin treatment, but while latent transforming growth factor β-binding protein (LTBP2) is recognized as a potential regulator in GC, its specific role in cisplatin resistance is not fully understood. This study investigated LTBP2's impact on cisplatin resistance in GC. LTBP2 expression was assessed in various GC cell lines, and its correlation with cisplatin sensitivity was determined through cell viability assays. Lentivirus-mediated LTBP2 silencing in HGC-27 cells demonstrated enhanced cisplatin sensitivity, reduced cell proliferation, and inhibition of the NF-κB2/Bcl-3/cyclin D1 pathway. Additionally, transient transfection overexpressed the NFκB2 gene in LTBP2-silenced HGC-27/DDPR cells, restoring cisplatin sensitivity and upregulating p52/Bcl-3/cyclin D1. In conclusion, silencing LTBP2 could effectively inhibit cell proliferation and mitigate cisplatin resistance via the NFKB noncanonical pathway NFKB2 p52/Bcl-3/cyclin D1. These findings propose LTBP2 as a potential therapeutic target for overcoming cisplatin resistance in GC patients.

Suppression of Bcl3 Disrupts Viability of Breast Cancer Cells through Both p53-Dependent and p53-Independent Mechanisms via Loss of NF-κB Signalling

The NF-κB co-factor Bcl3 is a proto-oncogene that promotes breast cancer proliferation, metastasis and therapeutic resistance, yet its role in breast cancer cell survival is unclear. Here, we sought to determine the effect of Bcl3 suppression alone on breast cancer cell viability, with a view to informing future studies that aim to target Bcl3 therapeutically. Bcl3 was suppressed by siRNA in breast cancer cell lines before changes in viability, proliferation, apoptosis and senescence were examined. Bcl3 suppression significantly reduced viability and was shown to induce apoptosis in all cell lines tested, while an additional p53-dependent senescence and senescence-associated secretory phenotype was also observed in those cells with functional p53. The role of the Bcl3/NF-κB axis in this senescence response was confirmed via siRNA of the non-canonical NF-κB subunit NFKB2/p52, which resulted in increased cellular senescence and the canonical subunit NFKB1/p50, which induced the senescence-associated secretory phenotype. An analysis of clinical data showed a correlation between reduced relapse-free survival in patients that expressed high levels of Bcl3 and carried a p53 mutation. Together, these data demonstrate a dual role for Bcl3/NF-κB in the maintenance of breast cancer cell viability and suggests that targeting Bcl3 may be more beneficial to patients with tumours that lack functional p53.

Genome-wide CRISPR screen identifies noncanonical NF-κB signaling as a regulator of density-dependent proliferation

Epithelial cells possess intrinsic mechanisms to maintain an appropriate cell density for normal tissue morphogenesis and homeostasis. Defects in such mechanisms likely contribute to hyperplasia and cancer initiation. To identify genes that regulate the density-dependent proliferation of murine mammary epithelial cells, we developed a fluorescence-activated cell sorting assay based on fluorescence ubiquitination cell cycle indicator, which marks different stages of the cell cycle with distinct fluorophores. Using this powerful assay, we performed a genome-wide CRISPR/Cas9 knockout screen, selecting for cells that proliferate normally at low density but continue to divide at high density. Unexpectedly, one top hit was Traf3, a negative regulator of NF-κB signaling that has never previously been linked to density-dependent proliferation. We demonstrate that loss of Traf3 specifically activates noncanonical NF-κB signaling. This in turn triggers an innate immune response and drives cell division independently of known density-dependent proliferation mechanisms, including YAP/TAZ signaling and cyclin-dependent kinase inhibitors, by blocking entry into quiescence.

Oroxylin A Suppresses the Cell Proliferation, Migration, and EMT via NF-κB Signaling Pathway in Human Breast Cancer Cells

Oroxylin A is a natural extract and has been reported to have a remarkable anticancer function. However, the mechanism of its anticancer activity remains not quite clear. In this study, we examined the inhibiting effects of Oroxylin A on breast cancer cell proliferation, migration, and epithelial-mesenchymal transition (EMT) and its possible molecular mechanism. The cytoactive and inflammatory factors were analyzed via Cell Counting Kit-8 assay and ELISA assay, respectively. Flow cytometry and western blotting were used to assess the cell proliferation. In addition, a wound healing assay and transwell assay were used to detect cell invasion and migration. qRT-PCR and western blot were employed to determine the effect of Oroxylin A on the EMT formation. Moreover, expression level of protein related to NF-κB signaling pathway was determined by western blot. The results revealed that Oroxylin A attenuated the cytoactivity of MDA-MB-231 cells in a dose- and a time-dependent manner. Moreover, cell proliferation, invasion, and migration of breast cancer cells were inhibited by Oroxylin A compared to the control. The mRNA and protein expression levels of E-cadherin were remarkably increased while N-cadherin and Vimentin remarkably decreased. Besides, Oroxylin A suppressed the expression of inflammatory factors and NF-κB activation. Furthermore, we also found that supplement of TNF-α reversed the effects of Oroxylin A on the cell proliferation, invasion, migration, and EMT in breast cancer cells. Taken together, our results suggested that Oroxylin A inhibited the cell proliferation, invasion, migration, and EMT through inactivating NF-κB signaling pathway in human breast cancer cells. These findings strongly suggest that Oroxylin A could be a therapeutic potential candidate for the treatment of breast cancer.

BCL-3 promotes a cancer stem cell phenotype by enhancing β-catenin signalling in colorectal tumour cells

To decrease bowel cancer incidence and improve survival, we need to understand the mechanisms that drive tumorigenesis. Recently, B-cell lymphoma 3 (BCL-3; a key regulator of NF-κB signalling) has been recognised as an important oncogenic player in solid tumours. Although reported to be overexpressed in a subset of colorectal cancers (CRCs), the role of BCL-3 expression in colorectal tumorigenesis remains poorly understood. Despite evidence in the literature that BCL-3 may interact with β-catenin, it is perhaps surprising, given the importance of deregulated Wnt/β-catenin/T-cell factor (TCF) signalling in colorectal carcinogenesis, that the functional significance of this interaction is not known. Here, we show for the first time that BCL-3 acts as a co-activator of β-catenin/TCF-mediated transcriptional activity in CRC cell lines and that this interaction is important for Wnt-regulated intestinal stem cell gene expression. We demonstrate that targeting BCL-3 expression (using RNA interference) reduced β-catenin/TCF-dependent transcription and the expression of intestinal stem cell genes LGR5 and ASCL2. In contrast, the expression of canonical Wnt targets Myc and cyclin D1 remained unchanged. Furthermore, we show that BCL-3 increases the functional stem cell phenotype, as shown by colorectal spheroid and tumoursphere formation in 3D culture conditions. We propose that BCL-3 acts as a driver of the stem cell phenotype in CRC cells, potentially promoting tumour cell plasticity and therapeutic resistance. As recent reports highlight the limitations of directly targeting cancer stem cells (CSCs), we believe that identifying and targeting drivers of stem cell plasticity have significant potential as new therapeutic targets.

This article has an associated First Person interview with the first author of the paper.

Summary: BCL-3 acts as a co-activator of β-catenin/TCF-mediated transcriptional activity, driving a stem-cell-like phenotype in colorectal cancer cells, with implications for tumour cell plasticity and therapeutic resistance.

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

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

Inhibition of PHLPP2/cyclin D1 protein translation contributes to the tumor suppressive effect of NFκB2 (p100)

Although the precursor protein of NFκB2 (p100) is thought to act as a tumor suppressor in mammalian cells, the molecular mechanism of its anti-tumor activity is far from clear. Here, we are, for the first time, to report that p100 protein expression was dramatically decreased in bladder cancers of N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-treated mice and human patients. Knockdown of p100 in cultured human bladder cancer cells promoted anchorage-independent growth accompanied with elevating abundance of cell-cycle-related proteins and accelerated cell-cycle progression. Above effects could be completely reversed by ectopically expression of p100, but not p52. Mechanistically, p100 inhibited Cyclin D1 protein translation by activating the transcription of LARP7 and its hosted miR-302d, which could directly bind to 3'-UTR of cyclin d1 mRNA and inhibited its protein translation. Furthermore, p100 suppressed the expression of PHLPP2 (PH domain and leucine-rich repeat protein phosphatases 2), thus promoting CREB phosphorylation at Ser133 and subsequently leading to miR-302d transcription. Taken together, our studies not only for the first time establish p100 as a key tumor suppressor of bladder cancer growth, but also identify a novel molecular cascade of PHLPP2/CREB/miR-302d that mediates the tumor suppressive function of p100.

Uncaria tomentosa (Willd. ex Schult.) DC (Rubiaceae) Sensitizes THP-1 Cells to Radiation-induced Cell Death

Background:

Uncaria tomentosa (Willd. ex Schult.) DC (Rubiaceae), known as Cat's Claw or Uña de gato, is a traditionally used medicinal plant native to Peru. Some studies have shown that U. tomentosa can act as an antiapoptotic agent and enhance DNA repair in chemotherapy-treated cells although others have shown that U. tomentosa enhanced apoptosis.

Objective:

To determine if treatment with U. tomentosa can significantly enhance cell death in THP-1 cells exposed to ionizing radiation.

Materials and Methods:

THP-1 monocyte-like cells were treated with ethanolic extracts of U. tomentosa in the presence or absence of bacterial lipopolysaccharide and then exposed to ionizing radiation. Cell proliferation was assessed by MTT and clonogenic assays and the effects on cell cycle measured by flow cytometry and immunoblotting. Changes in cell signaling were determined by immunoblotting and cytokine ELISA and activation of apoptosis measured by caspase activation and DNA fragmentation analysis.

Results:

Treatment of THP-1 cells with U. tomentosa had a small effect on cell proliferation. However, when the U. tomentosa-pretreated cells were also subjected to 5–9 Gy ionizing radiation, they showed a significant decrease in cell proliferation and increased cellular apoptosis as measured by DNA fragmentation and caspase activation. Treatment with U. tomentosa also decreased the expression of Cyclin E and Cyclin B, key regulators of normal cell cycle progression, and decreased the phosphorylation of various stress-activated, cell survival proteins including p38, ERK, and SAP/JNK kinase.

Conclusions:

These results suggest that U. tomentosa could be useful in enhancing cell death following anticancer therapies including ionizing radiation.

SUMMARY

Treatment of THP-1 cells with Uncaria tomentosa increases their susceptibility to X-rays. The combination of Uncaria tomentosa and X-ray exposure strongly inhibits cell signaling and promotes apoptosis.

Abbreviations Used: LPS: Lipopolysaccharide, TNF: Tumor necrosis factor: IL-1, Interleukin-1: SDS: Sodium dodecylsulphate, TBS: Tris-buffered saline.

A Synthetic Loop Replacement Peptide That Blocks Canonical NF-κB Signaling

Aberrant canonical NF-κB signaling is implicated in diseases from autoimmune disorders to cancer. A major therapeutic challenge is the need for selective inhibition of the canonical pathway without impacting the many non-canonical NF-κB functions. Here we show that a selective peptide-based inhibitor of canonical NF-κB signaling, in which a hydrogen bond in the NBD peptide is synthetically replaced by a non-labile bond, shows an about 10-fold increased potency relative to the original inhibitor. Not only is this molecule, NBD2, a powerful tool for dissection of canonical NF-κB signaling in disease models and healthy tissues, the success of the synthetic loop replacement suggests that the general strategy could be useful for discovering modulators of the many protein-protein interactions mediated by such structures.

Shh and p50/Bcl3 signaling crosstalk drives pathogenesis of BCCs in Gorlin syndrome

Nevoid basal cell carcinoma syndrome (NBCCS) is a rare autosomal dominant disorder that is due, in large measure, to aberrant Shh signaling driven by mutations in the tumor suppressor gene Ptch1. Here, we describe the development of Ptch1+/-/ SKH-1 mice as a novel model of this disease. These animals manifest many features of NBCCS, including developmental anomalies and are remarkably sensitive to both ultraviolet (UVB) and ionizing radiation that drive the development of multiple BCCs. Just as in patients with NBCCS, Ptch1+/-/SKH-1 also spontaneously develops BCCs and other neoplasms such as rhabdomyomas/rhabdomyosarcomas. Administration of smoothened inhibitors (vismodegib/itraconazole/cyclopamine) or non-steroidal anti-inflammatory drug (sulindac/sulfasalazine) each result in partial resolution of BCCs in these animals. However, combined administration of these agents inhibits the growth of UVB-induced BCCs by >90%. Employing small molecule- and decoy-peptide-based approaches we further affirm that complete remission of BCCs could only be achieved by combined inhibition of p50-NFκB/Bcl3 and Shh signaling. We posit that Ptch1+/-/SKH-1 mice are a novel and relevant animal model for NBCCS. Understanding mechanisms that govern genetic predisposition to BCCs should facilitate our ability to identify and treat NBCCS gene carriers, including those at risk for sporadic BCCs while accelerating development of novel therapeutic modalities for these patients.

Lack of Oestrogenic Inhibition of the Nuclear Factor-κB Pathway in Somatolactotroph Tumour Cells

Activation of nuclear factor (NF)-κB promotes cell proliferation and inhibits apoptosis. We have previously shown that oestrogens sensitise normal anterior pituitary cells to the apoptotic effect of tumour necrosis factor (TNF)-α by inhibiting NF-κB nuclear translocation. In the present study, we examined whether oestrogens also modulate the NF-κB signalling pathway and apoptosis in GH3 cells, a rat somatolactotroph tumour cell line. As determined by Western blotting, 17β-oestradiol (E2 ) (10(-9) m) increased the nuclear concentration of NF-κB/p105, p65 and p50 in GH3 cells. However, E2 did not modify the expression of Bcl-xL, a NF-κB target gene. TNF-α induced apoptosis of GH3 cells incubated in either the presence or absence of E2 . Inhibition of the NF-kB pathway using BAY 11-7082 (BAY) (5 μm) decreased the viability of GH3 cells and increased the percentage of terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)-positive GH3 cells. BAY also increased TNF-α-induced apoptosis of GH3 cells, an effect that was further increased by an inhibitor of the c-Jun N-terminal protein kinase pathway, SP600125 (10 μm). We also analysed the role of the NF-κB signalling pathway on proliferation and apoptosis of GH3 tumours in vivo. The administration of BAY to nude mice bearing GH3 tumours increased the number of TUNEL-positive cells and decreased the number of proliferating GH3 cells. These findings suggest that GH3 cells lose their oestrogenic inhibitory action on the NF-κB pathway and that the pro-apoptotic effect of TNF-α on these tumour pituitary cells does not require sensitisation by oestrogens as occurs in normal pituitary cells. NF-κB was required for the survival of GH3 cells, suggesting that pharmacological inhibition of the NF-κB pathway could interfere with pituitary tumour progression.

NF-κB and the cell cycle

The NF-κB (nuclear factor κB) transcription factor family is a pleiotropic regulator of many cellular pathways, providing a mechanism for the cell to respond to a wide variety of stimuli and environmental challenges. It is not surprising therefore that an important component of NF-κB's function includes regulation of the cell cycle. However, this aspect of its behaviour is often overlooked and receives less attention than its ability to induce inflammatory gene expression. In the present article, we provide an updated review of the current state of our knowledge about integration of NF-κB activity with cell cycle regulation, including newly characterized direct and indirect target genes in addition to the mechanisms through which NF-κB itself can be regulated by the cell cycle.

Differential regulation of cyclin D1 expression by protein kinase C α and ϵ signaling in intestinal epithelial cells

Cellular accumulation of cyclin D1, a key regulator of cell proliferation and tumorigenesis, is subject to tight control. Our previous studies have identified PKCα as a negative regulator of cyclin D1 in the intestinal epithelium. However, treatment of non-transformed IEC-18 ileal crypt cells with PKC agonists has a biphasic effect on cyclin D1 expression. Initial PKCα-mediated down-regulation is followed by recovery and subsequent accumulation of the cyclin to levels markedly higher than those seen in untreated cells. Using protein overexpression strategies, siRNA, and pharmacological inhibitors, we now demonstrate that the recovery and hyperinduction of cyclin D1 reflect the combined effects of (a) loss of negative signals from PKCα due to agonist-induced PKCα down-regulation and (b) positive effects of PKCϵ. PKCϵ-mediated up-regulation of cyclin D1 requires sustained ERK stimulation and transcriptional activation of the proximal cyclin D1 (CCDN1) promoter, without apparent involvement of changes in protein stability or translation. PKCϵ also up-regulates cyclin D1 expression in colon cancer cells, through mechanisms that parallel those in IEC-18 cells. Although induction of cyclin D1 by PKCϵ is dependent on non-canonical NF-κB activation, the NF-κB site in the proximal promoter is not required. Instead, cyclin D1 promoter activity is regulated by a novel interaction between NF-κB and factors that associate with the cyclic AMP-response element adjacent to the NF-κB site. The differential effects of PKCα and PKCϵ on cyclin D1 accumulation are likely to contribute to the opposing tumor-suppressive and tumor-promoting activities of these PKC family members in the intestinal epithelium.

NF-κB inducing kinase, a central signaling component of the non-canonical pathway of NF-κB, contributes to ovarian cancer progression

Ovarian cancer is one of the leading causes of female death and the development of novel therapeutic approaches is urgently required. Nuclear factor-κB (NF-κB) is constitutively activated in several types of cancer including ovarian cancer and is known to support the survival of cancer cells. However, molecular mechanisms of persistent activation of NF-κB in ovarian cancer remain largely unknown. We report here that, in addition to the previously reported canonical activation, NF-κB is activated through the noncanonical pathway in ovarian cancer cells. RNA interference-mediated silencing of NF-κB inducing kinase (NIK), a central regulator of the noncanonical pathway, reduced the NF-κB2/p52 DNA binding activity and NF-κB-dependent reporter gene expression as well as NF-κB target gene expression. Notably, anchorage-dependent and -independent cell growth was impaired in NIK-depleted cells. Depletion of NIK also suppressed tumor formation in the nude mouse xenograft assay. These results indicate that NIK plays a key role in constitutive NF-κB activation and the progression of ovarian cancer cells and suggest that NIK represents an attractive therapeutic target for ovarian cancer.

Identifying grade/stage-related active modules in human co-regulatory networks: a case study for breast cancer

The histological grade/stage of tumor is widely acknowledged as an important clinical prognostic factor for cancer progression. Recent experimental studies have explored the following two topics at the molecular level: (1) whether or not gene expression levels vary by different degrees among different tumor grades/stages, and (2) whether some well-defined modules could distinguish one grade/stage from another. In this article, using breast cancer as an example, we investigated this topic and identified grade/stage-related active modules under the framework of a weighted network integrated from a human protein interaction network and a transcriptional regulatory network. Our results enabled us to draw the conclusion that the gene expression profile could provide more clues about tumor grade, but reveals less evidence about tumor stage. In addition, we found that our modular biomarker method had additional advantages in identifying some tumor grade/stage-related genes with slightly altered expression. According to our case study, the framework we introduced could be used for other cancers to identify their modules during grading or staging.

NF-κB signaling pathways: role in nervous system physiology and pathology

Intracellular pathways related to cell survival regulate neuronal physiology during development and neurodegenerative disorders. One of the pathways that have recently emerged with an important role in these processes is nuclear factor-κB (NF-κB). The activity of this pathway leads to the nuclear translocation of the NF-κB transcription factors and the regulation of anti-apoptotic gene expression. Different stimuli can activate the pathway through different intracellular cascades (canonical, non-canonical, and atypical), contributing to the translocation of specific dimers of the NF-κB transcription factors, and each of these dimers can regulate the transcription of different genes. Recent studies have shown that the activation of this pathway regulates opposite responses such as cell survival or neuronal degeneration. These apparent contradictory effects depend on conditions such as the pathway stimuli, the origin of the cells, or the cellular context. In the present review, the authors summarize these findings and discuss their significance with respect to survival or death in the nervous system.

Terminalia chebula extract acts as a potential NF-κB inhibitor in human lymphoblastic T cells

Terminalia chebula (TC) is native to southern Asia to southwestern China and is used in traditional medicine for the treatment of human ailments including malignant tumors and diabetes. This plant also has antibacterial and immunomodulatory properties. Nuclear factor kappa-light chain-enhancer of activated B cells (NF-κB) is responsible for the expression of numerous genes involved in cell survival, proliferation, angiogenesis, inflammation, invasion and metastasis, among other processes. This study aims to assess the NF-κB inhibitory effect of TC extract in human lymphoblastic T (Jurkat) cells. The effects of TC extract were investigated using the FRET-based Gene Blazer technique in transfected Jurkat-NF-κB-RE-bla cells. The concentration of TC extract required for NF-κB inhibition was determined by a cell proliferation assay. Treatment with TC extract (50 μg/mL) inhibited NF-κB activity and protected against IκBα degradation and strongly suppressed IκBα phosphorylation in Jurkat-NF-κB-RE-bla cells. This treatment might be crucial for inhibiting NF-κB translocation and activation. In addition, the TC extract downregulated certain NF-κB regulated genes, including IL-8 and MCP-1, in Jurkat-NF-κB-RE-bla cells. Moreover, gallic acid was identified from the TC extract demonstrating its ability to inhibit NF-κB activity in Jurkat-NF-κB-RE-bla cells. Further studies to identify the role of gallic acid in NF-κB inhibition may uncover the crucial antiinflammatory and antitumor properties of the TC extract.

Characterization of Prox1 and VEGFR-3 expression and lymphatic phenotype in normal organs of mice lacking p50 subunit of NF-κB

OBJECTIVE

Inflammation and NF-κB are highly associated with lymphangiogenesis but the underlying mechanisms remain unclear. We recently established that activated NF-κB p50 subunit increases expression of the main lymphangiogenic mediators, VEGFR-3 and its transcriptional activator, Prox1. To elucidate the role of p50 in lymphatic vasculature, we compared LVD and phenotype in p50 KO and WT mice.

METHODS

Normal tissues from KO and WT mice were stained for LYVE-1 to calculate LVD. VEGFR-3 and Prox1 expressions were analyzed by immunofluorescence and qRT-PCR.

RESULTS

Compared with WT, LVD in the liver and lungs of KO mice was reduced by 39% and 13%, respectively. This corresponded to 25-44% decreased VEGFR-3 and Prox1 expression. In the MFP, LVD was decreased by 18% but VEGFR-3 and Prox1 expression was 80-140% higher than in WT. Analysis of p65 and p52 NF-κB subunits and an array of inflammatory mediators showed a significant increase in p50 alternative pathways in the MFP but not in other organs.

CONCLUSIONS

These findings demonstrate the role of NF-κB p50 in regulating the expression of VEGFR-3, Prox1 and LVD in the mammary tissue, liver, and lung.

Rimonabant reduces keratinocyte viability by induction of apoptosis and exerts topical anti-inflammatory activity in mice

BACKGROUND AND PURPOSE

There is growing evidence that the cannabinoid CB(1) receptor antagonist, rimonabant (SR141716) exerts potential anti-proliferative and anti-inflammatory actions. Here, we have assessed the effects of rimonabant in vitro in murine immortalized keratinocytes and in vivo by assaying the topical anti-inflammatory activity.

EXPERIMENTAL APPROACH

Cell viability and death in a keratinocyte cell line (C5N cells) were measured by Trypan blue exclusion assay and cytotoxicity by sulphorhodamine B test. Cell cycle progression was assessed by flow cytometry and the expression of apoptotic and anti-apoptotic markers, cyclins, pathways of signal transduction and CB1 receptor levels were evaluated by Western blot. The topical anti-inflammatory properties of rimonabant were analysed by inhibition of croton oil-induced ear dermatitis in mice.

KEY RESULTS

Rimonabant reduced cell viability and induced apoptosis as shown by the enhanced number of cells in the subG0 phase of the cell cycle, the expression of Bax and reduced levels of Bcl-2 and X-inhibitor of apoptosis protein. In addition, reduced levels of phosphorylated serine/threonine protein kinase Akt and nuclear factor-kappa B were detected associated with regulation of total nuclear factor-kappa B and inhibitor of kappa B-α, phosphorylated inhibitor of kappa B-α, cyclins D1, E and A. In croton oil-induced ear dermatitis, rimonabant significantly reduced oedema and leukocyte infiltrate.

CONCLUSIONS AND IMPLICATIONS

Rimonabant reduced cell viability, inducing cell death in keratinocytes and decreased croton oil-induced ear dermatitis. Our findings suggest a potential application of rimonabant as a topical anti-inflammatory drug. We did not assess the involvement of CB(1) receptors in these effects of rimonabant.

t10,c12-CLA decreases adiposity in peripubertal mice without dose-related detrimental effects on mammary development, inflammation status, and metabolism

The trans 10, cis 12-conjugated linoleic acid (10,12-CLA) isomer reduces adiposity in several animal models. In the mouse, however, this effect is associated with adipose tissue inflammation, hyperinsulinemia and hepatic lipid accumulation. Moreover, 10,12-CLA was recently shown to promote mammary ductal hyperplasia and ErbB2/Her2-driven mammary cancer in the mouse. Reasons for detrimental effects of 10,12-CLA on the mouse mammary gland could relate to its effect on the mammary fat pad (MFP), which is essential for normal development. Accordingly, we hypothesized that mammary effects of 10,12-CLA were mediated through the MFP in a dose-dependent manner. Female FVB mice were fed 10,12-CLA at doses of 0%, 0.1%, 0.2%, or 0.5% of the diet from day 24 of age, and effects on mammary development and metabolism were measured on day 49. The 0.5% dose reduced ductal elongation and caused premature alveolar budding. These effects were associated with increased expression of inflammatory markers and genes shown to alter epithelial growth (IGF binding protein-5) and alveolar budding (TNF-α and receptor of activated NF-κB ligand). The 0.5% dose also caused hyperinsulinemia and hepatic lipid accumulation. In contrast, the 0.1% 10,12-CLA dose had no adverse effects on mammary development, metabolic events, and inflammatory responses, but remained effective in decreasing adipose weights and lipogenic gene expression. These results show that a low dose of 10,12-CLA reduces adiposity in the mouse without negative effects on mammary development, inflammation, and metabolism, and suggest that previously reported detrimental effects relate to the use of excessive doses.

Regulation of cyclin D1 gene expression

Cyclin D1 is a key regulator of cell proliferation and its expression is subject to both transcriptional and post-transcriptional regulation. In different cellular contexts, different pathways assume a dominant role in regulating its expression, whereas their disregulation can contribute to overexpression of cyclin D1 in tumorigenesis. Here, we discuss the ability of the NF-kappaB (nuclear factor kappaB)/IKK [IkappaB (inhibitor of NF-kappaB) kinase] pathways to regulate cyclin D1 gene transcription and also consider the newly discovered role of the SNARP (SNIP1/SkIP-associated RNA processing) complex as a co-transcriptional regulator of cyclin D1 RNA stability.

Increased H2O2 level in exhaled breath condensate in primary breast cancer patients

PURPOSE

This study was designed to assess exhaled hydrogen peroxide (H(2)O(2)), blood serum antioxidant capacity, and tumor necrosis factor-alpha (TNFalpha) in primary breast cancer (PBC).

METHODS

The study included 34 consecutive, non-smoking PBC patients (aged 62.5 +/- 13.5 at surgery) prior to the treatments, qualified for modified radical mastectomy and not undergoing any adjuvant systemic therapy, and 33 healthy controls. The post surgery pathological assessment included tissue expression of estrogen (ER) and progesterone (PR) receptors, and epidermal growth factor receptor type 2 (HER-2/neu). Exhaled H(2)O(2) was determined fluorometrically in the exhaled breath condensate (EBC). Blood serum antioxidant capacity and TNFalpha levels were assessed with ferric reducing ability of plasma (FRAP) and ELISA immunoassay, respectively.

RESULTS

In PBC patients, 10 ER, 11 PR, and 9 HER-2/neu positive tumors were identified and HER-2/neu score was 2+ in 20% of all tumors. Median (Me) H(2)O(2) was increased up to 0.44 microM (interquartile range IR: 0.20-1.25 microM) compared with healthy control of 0.36 microM (IR: 0.12-0.48 microM; p < 0.05). The H(2)O(2) concentration in EBC was significantly correlated (tau = 0.27; p = 0.03) and increased in cases with nodal metastases (n = 12; p = 0.04). Serum TNFalpha was increased up to 51.7 +/- 21.0 pg/ml compared with controls 17.2 +/- 3.65 pg/ml (p < 0.05). FRAP was increased to 1.41 +/- 0.37 mM Fe(2+) compared with control 1.19 +/- 0.17 mM Fe(2+); (p = 0.006).

CONCLUSIONS

This is the first study to demonstrate increased H(2)O(2) in exhaled breath condensate in patients with localized breast malignancy and its relation with clinical severity.

Tumor necrosis factor deficiency inhibits mammary tumorigenesis and a tumor necrosis factor neutralizing antibody decreases mammary tumor growth in neu/erbB2 transgenic mice

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic cytokine that is synthesized and secreted by cells of the immune system, as well as by certain epithelia and stroma. Based on our previous studies demonstrating TNF-stimulated proliferation of normal and malignant mammary epithelial cells, we hypothesized that TNF might promote the growth of breast cancer in vivo. To test this, we generated bigenic mice that overexpressed activated neu/erbB2 in the mammary epithelium and whose TNF status was wild-type, heterozygous, or null. Mammary tumorigenesis was significantly decreased in TNF-/- mice (n = 30) compared with that in TNF+/+ mice (n = 27), with a palpable tumor incidence of 10.0% and 44.4%, and palpable tumors/mouse of 0.10 +/- 0.06 and 0.67 +/- 0.17, respectively. Tumorigenesis in the heterozygous group fell between that in the TNF+/+ and TNF-/- groups, but was not significantly different from either of the homozygous groups. The decreased tumor development in the TNF-/- mice was associated with a decreased proliferative index in the lobular and ductal mammary epithelium. To further investigate the role of TNF in breast cancer, mammary tumor-bearing mice whose tumors overexpressed wild-type neu/erbB2 were treated with a TNF-neutralizing antibody or a control antibody for 4 weeks (n = 20/group). Mammary tumor growth was significantly inhibited in mice treated with the anti-TNF antibody compared with the control antibody. Together, these data show a stimulatory role for TNF in the growth of breast tumors and suggest that TNF antagonists may be effective in a subset of patients with breast cancer.

A new cross-talk between the aryl hydrocarbon receptor and RelB, a member of the NF-kappaB family

The discovery of the new crosstalk between the aryl hydrocarbon receptor (AhR) and the NF-kappaB subunit RelB may extend our understanding of the biological functions of the AhR and at the same time raises a number of questions, which will be addressed in this review. The characteristics of this interaction differ from that of AhR with RelA in that the latter appears to be mostly negative unlike the collaborative interactions of AhR/RelB. The AhR/RelB dimer is capable of binding to DNA response elements including the dioxin response element (DRE) as well as NF-kappaB binding sites supporting the activation of target genes of the AhR as well as NF-kappaB pathway. Further studies show that AhR/RelB complexes can be found not only in lymphoid cells but also in a human hepatoma cell line (HepG2) or breast cancer cell line (MDA-MB-231). RelB has been implicated in carcinogenesis of breast cancer for instance and RelB is known to be a critical factor for the function and differentiation of dendritic cells; interestingly the participation of AhR in both processes has been suggested recently, which offers the great potential to expand the scope of the physiological roles of the AhR. There is evidence indicating that RelB may serve as a pro-survival factor, including its ability to promote "inflammation resolution" besides the association of RelB with inflammatory disorders. Based on such information, a hypothesis has been proposed in this review that AhR together with RelB functions as a coordinator of inflammatory responses.

Altered glycosylation of Tamm-Horsfall glycoprotein derived from renal allograft recipients leads to changes in its biological function

BACKGROUND

Human urinary Tamm-Horsfall glycoprotein (THP) is a pleotropic protein that binds different cytokines and stimulates various immunocompetent cells. It is unclear whether these important functions of THP are altered in renal transplant patients.

METHODS

We purified THPs from normal individuals (N-THP) and renal transplant patients receiving potent immunosuppressants (R-THP). The carbohydrate (CHO) compositions of THPs were probed by lectin-blotting and lectin-binding ELISA. The functions of THP were assessed by immune cell-stimulation as well as C1q, IL-1beta, IL-8 and TNF-alpha-binding assays. The roles of CHO moieties in THPs were analyzed using CHO-degrading enzyme digestion.

RESULTS

Compared to that of N-THP, the binding capacity of R-THP to Maackia amurensis, Galanthus nivalis and Datura stamonium decreased, indicating that R-THP contained lesser amount of Siaalpha(2,3)Gal/GalNAc, mannose residues, and beta(1,4)GlcNAc, but not GlcNAc/branched mannose. The binding capacity of R-THP to complement C1q and tumor necrosis factor (TNF)-alpha was also decreased. The stimulating effect of R-THP on mononuclear cell (MNC) proliferation and polymorphonuclear neutrophil (PMN) phagocytosis was less potent than that of N-THP. We found that the defective MNC-stimulation by R-THP was due to impaired NF-kappaB p52 nuclear translocation. The cell-stimulating effects of N- and R-THP could be abolished by digesting them with CHO-degrading enzymes, beta-galactosidase and neuraminidase. Interestingly, a potent apoptosis-inducing effect of R-THP on MNC and PMN was noted.

CONCLUSIONS

R-THP is not only modified in glycosylation but bears an apoptosis-inducing capacity on MNC and PMN, leading to an impaired immune function in renal transplant patients.

A cell cycle regulatory network controlling NF-kappaB subunit activity and function

Aberrantly active NF-kappaB complexes can contribute to tumorigenesis by regulating genes that promote the growth and survival of cancer cells. We have investigated NF-kappaB during the cell cycle and find that its ability to regulate the G1-phase expression of key proto-oncogenes is subject to regulation by the integrated activity of IkappaB kinase (IKK)alpha, IKKbeta, Akt and Chk1. The coordinated binding of NF-kappaB subunits to the Cyclin D1, c-Myc and Skp2 promoters is dynamic with distinct changes in promoter occupancy and RelA(p65) phosphorylation occurring through G1, S and G2 phases, concomitant with a switch from coactivator to corepressor recruitment. Akt activity is required for IKK-dependent phosphorylation of NF-kappaB subunits in G1 and G2 phases, where Chk1 is inactive. However, in S-phase, Akt is inactivated, while Chk1 phosphorylates RelA and associates with IKKalpha, inhibiting the processing of the p100 (NF-kappaB2) subunit, which also plays a critical role in the regulation of these genes. These data reveal a complex regulatory network integrating NF-kappaB with the DNA-replication checkpoint and the expression of critical regulators of cell proliferation.