Cellular proliferation and activation of NF kappa B are induced by autocrine production of tumor necrosis factor alpha in the human T lymphoma line HuT 78

Frequent and Persistent PLCG1 Mutations in Sézary Cells Directly Enhance PLCγ1 Activity and Stimulate NFκB, AP-1, and NFAT Signaling

Phospholipase C Gamma 1 (PLCG1) is frequently mutated in primary cutaneous T-cell lymphoma (CTCL). This study functionally interrogated nine PLCG1 mutations (p.R48W, p.S312L, p.D342N, p.S345F, p.S520F, p.R1158H, p.E1163K, p.D1165H, and the in-frame indel p.VYEEDM1161V) identified in Sézary Syndrome, the leukemic variant of CTCL. The mutations were demonstrated in diagnostic samples and persisted in multiple tumor compartments over time, except in patients who achieved a complete clinical remission. In basal conditions, the majority of the mutations confer PLCγ1 gain-of-function activity through increased inositol phosphate production and the downstream activation of NFκB, AP-1, and NFAT transcriptional activity. Phosphorylation of the p.Y783 residue is essential for the proximal activity of wild-type PLCγ1, but we provide evidence that activating mutations do not require p.Y783 phosphorylation to stimulate downstream NFκB, NFAT, and AP-1 transcriptional activity. Finally, the gain-of-function effects associated with the p.VYEEDM1161V indel suggest that the C2 domain may have a role in regulating PLCγ1 activity. These data provide compelling evidence to support the development of therapeutic strategies targeting mutant PLCγ1.

Analysis of the Effect of Gentian Violet on Apoptosis and Proliferation in Cutaneous T-Cell Lymphoma in an In Vitro Study

Importance

Triggering the extrinsic apoptotic pathway is an effective way to kill cutaneous T-cell lymphoma (CTCL) cells in vitro and ex vivo.

Objective

To compare small molecules that induce extrinsic apoptosis in CTCL to identify and analyze compounds that induce high levels of tumor cell death and block tumor cell growth.

Design, Setting, and Participants

From November 5, 2014, to January 30, 2018, this study performed high-throughput small molecule screening of 1710 compounds followed by detailed analysis of the ability of gentian violet (GV) to promote apoptosis and inhibit proliferation of CTCL cells.

Exposures

In vitro and ex vivo analyses using enzyme-linked immunosorbent assays, flow cytometry, and immunoblotting.

Main Outcomes and Measures

Apoptosis, cleaved caspases, extrinsic apoptotic death receptors and ligands, cell proliferation, nuclear factor-κB expression, and other factors.

Results

This study used high-throughput screening to detect cleaved caspase 8 induced in CTCL cells by 1710 unique compounds. The nonprescription, topical antimicrobial remedy GV induced more total apoptosis than did nitrogen mustard (mechlorethamine). Furthermore, GV induced 4 to 6 times greater apoptosis in CTCL lines than in normal keratinocytes, suggesting a favorable topical toxicity profile. In addition to increasing caspase 8, GV also upregulated death receptors 4 and 5, tumor necrosis factor (TNF)-related apoptosis-inducing ligand, and Fas ligand but not the Fas receptor, TNF receptor, or TNF-α ligand. These results are consistent with induction of extrinsic apoptosis via the Fas and TNF-related apoptosis-inducing ligand pathways. Increased phosphorylation of phospholipase C-γ1, Ca2+ influx, and reactive oxygen species were also detected, indicating that the mechanism of Fas ligand upregulation involves key elements of the activation-induced cell death pathway. In ex vivo studies, 1-μmol/L GV induced up to 90% CTCL apoptosis in Sézary blood cells. In addition, GV reduced expression of antiapoptotic myeloid cell leukemia 1 and proproliferative nuclear factor-κB components and increased inhibitory κB levels. This finding was associated with cell cycle arrest and reduced CTCL tumor cell proliferation. Furthermore, the CTCL killing associated with GV was augmented when used in combination with methotrexate.

Conclusions and Relevance

This study found that GV attacked tumor viability and growth in CTCL. Although purple at neutral pH, GV can be rendered colorless by altering its pH. These preclinical findings may help to broaden knowledge of the antineoplastic features of GV and provide a rationale for clinical studies of its use as a novel, inexpensive, topical therapy for CTCL that is available worldwide.

ONC201 selectively induces apoptosis in cutaneous T-cell lymphoma cells via activating pro-apoptotic integrated stress response and inactivating JAK/STAT and NF-κB pathways

Cutaneous T-cell lymphomas (CTCLs) are extremely symptomatic and still incurable, and more effective and less toxic therapies are urgently needed. ONC201, an imipridone compound, has shown efficacy in pre-clinical studies in multiple advanced cancers. This study was to evaluate the anti-tumor activity of ONC201 on CTCL cells. The effect of ONC201 on the cell growth and apoptosis were evaluated in CTCL cell lines (n=8) and primary CD4+ malignant T cells isolated from CTCL patients (n=5). ONC201 showed a time-dependent cell growth inhibition in all treated cell lines with a concentration range of 1.25-10.0 μM. ONC201 also induced apoptosis in tested cells with a narrow concentration range of 2.5-10.0 μM, evidenced by increased Annexin V+ cells, accompanied by accumulated sub-G1 portions. ONC201 only induced apoptosis in CD4+ malignant T cells, not in normal CD4+ T cells. The activating transcription factor 4 (ATF4), a hallmark of integrated stress response, was upregulated in response to ONC201 whereas Akt was downregulated. In addition, molecules in JAK/STAT and NF-κB pathways, as well as IL-32β, were downregulated following ONC201 treatment. Thus, ONC201 exerts a potent and selective anti-tumor effect on CTCL cells. Its efficacy may involve activating integrated stress response through ATF4 and inactivating JAK/STAT and NF-κB pathways.

Genetics of Cutaneous T Cell Lymphoma: From Bench to Bedside

OPINION STATEMENT

Cutaneous T cell lymphomas (CTCLs) are non-Hodgkin lymphomas of skin homing T cells. Although early-stage disease may be limited to the skin, tumor cells in later stage disease can populate the blood, the lymph nodes, and the visceral organs. Unfortunately, there are few molecular biomarkers to guide diagnosis, staging, or treatment of CTCL. Diagnosis of CTCL can be challenging and requires the synthesis of clinical findings, histopathology, and T cell clonality studies; however, none of these tests are entirely sensitive or specific for CTCL. Treatment of CTCL is often empiric and is not typically based on specific molecular alterations, as is common in other cancers. In part, limitations in diagnosis and treatment selection reflect the limited insight into the genetic basis of CTCL. Recent next-generation sequencing has revolutionized our understanding of the mutational landscape in this disease. These analyses have uncovered ultraviolet radiation and recombination activating gene (RAG) endonucleases as important mutagens. Furthermore, these studies have revealed potentially targetable oncogenic mutations in the T cell receptor complex, NF-κB, and JAK-STAT signaling pathways. Collectively, these somatic mutations drive lymphomagenesis via cancer-promoting changes in proliferation, apoptosis, and T cell effector function. We expect that these genetic findings will launch a new era of precision medicine in CTCL.

TNFα up-regulates COX-2 in chronic progressive nephropathy through nuclear accumulation of RelB and NF-κB2

OBJECTIVE

The pathogenesis of progressive nephropathies involves inflammatory factors. The inhibition of cyclooxygenase-2 (COX-2) can limit renal damage and inflammation. However, the mechanism of up-regulation of COX-2 in nephropathy is poorly defined.

MATERIALS AND METHODS

Here we found that tumor necrosis factor alpha (TNFα) was involved in expression of COX-2 in normal rat kidney (NRK) cell line.

RESULTS

TNFα stimulated COX-2 production in a time-dependent manner in NRK cells by inducing nuclear accumulation of RelB and nuclear factor kappa B2 (NF-κB2) and their association with COX-2 gene promoter. Depletion of IκB-inducing kinase alpha, a positive regulator of activation of p100 processing to active p52, attenuated TNFα-induced COX-2 production. Furthermore, TNFα induced COX-2 production and nuclear import in anti-thymocyte serum (ATS) nephropathy.

DISCUSSION AND CONCLUSION

These data suggest that TNFα-RelB/p52 pathway may be involved in the early stages of renal damage, in part by stimulating COX-2 and inflammatory responses.

Bortezomib inhibits expression of TGF-β1, IL-10, and CXCR4, resulting in decreased survival and migration of cutaneous T cell lymphoma cells

Increased expression of the immunosuppressive cytokines, TGF-β1 and IL-10, is a hallmark of the advanced stages of cutaneous T cell lymphoma (CTCL), where it has been associated with suppressed immunity, increased susceptibility to infections, and diminished antitumor responses. Yet, little is known about the transcriptional regulation of TGF-β1 and IL-10 in CTCL, and about their function in regulating the CTCL cell responses. In this article, we show that TGF-β1 and IL-10 expression in CTCL cells is regulated by NF-κB and suppressed by bortezomib (BZ), which has shown promising results in the treatment of CTCL. However, although the TGF-β1 expression is IκBα dependent and is regulated by the canonical pathway, the IL-10 expression is IκBα independent, and its inhibition by BZ is associated with increased promoter recruitment of p52 that characterizes the noncanonical pathway. TGF-β1 suppression decreases CTCL cell viability and increases apoptosis, and adding exogenous TGF-β1 increases viability of BZ-treated CTCL cells, indicating TGF-β1 prosurvival function in CTCL cells. In addition, TGF-β1 suppression increases expression of the proinflammatory cytokines IL-8 and IL-17 in CTCL cells, suggesting that TGF-β1 also regulates the IL-8 and IL-17 expression. Importantly, our results demonstrate that BZ inhibits expression of the chemokine receptor CXCR4 in CTCL cells, resulting in their decreased migration, and that the CTCL cell migration is mediated by TGF-β1. These findings provide the first insights into the BZ-regulated TGF-β1 and IL-10 expression in CTCL cells, and indicate that TGF-β1 has a key role in regulating CTCL survival, inflammatory gene expression, and migration.

Analysis of TGFβ1 and IL-10 transcriptional regulation in CTCL cells by chromatin immunoprecipitation

The immunosuppressive cytokines transforming growth factor β1 (TGFβ1) and interleukin-10 (IL-10) regulate a variety of biological processes including differentiation, proliferation, tissue repair, tumorigenesis, inflammation, and host defense. Aberrant expression of TGFβ1 and IL-10 has been associated with many types of autoimmune and inflammatory disorders, as well as with many types of cancer and leukemia. Patients with cutaneous T cell lymphoma (CTCL) have high levels of malignant CD4+ T cells expressing IL-10 and TGFβ1 that suppress the immune system and diminish the antitumor responses. The transcriptional regulation of TGFβ1 and IL-10 expression is orchestrated by several transcription factors, including NFκB. However, while the transcriptional regulation of pro-inflammatory and anti-apoptotic genes by NFκB has been studied extensively, much less is known about the NFκB regulation of immunosuppressive genes. In this chapter, we describe a protocol that uses chromatin immunoprecipitation (ChIP) to analyze the transcriptional regulation of TGFβ1 and IL-10 by measuring recruitment of NFκB p65, p50, c-Rel, Rel-B, and p52 subunits to TGFβ1 and IL-10 promoters in human CTCL Hut-78 cells.

The role of inflammation in leukaemia

Acute leukaemias are a group of malignancies characterised by the invasion of the bone marrow by immature haematopoietic precursors and differentiation arrest at various maturation steps. Multiplicity of intrinsic and extrinsic factors influences the transformation and progression of leukaemia. The intrinsic factors encompass genetic alterations of cellular pathways leading to the activation of, among others, inflammatory pathways (such as nuclear factor kappa B). The extrinsic components include, among others, the inflammatory pathways activated by the bone marrow microenvironment and include chemokines, cytokines and adhesion molecules. In this chapter, we review the role of inflammatory processes in the transformation, survival and proliferation of leukaemias, particularly the role of nuclear factor kappa B and its downstream signalling in leukaemias and the novel therapeutic strategies that exploit potentially unique properties of inflammatory signalling that offer interesting options for future therapeutic interventions.

Autocrine TNF-α production supports CML stem and progenitor cell survival and enhances their proliferation

Chronic myeloid leukemia (CML) stem cells are not dependent on BCR-ABL kinase for their survival, suggesting that kinase-independent mechanisms must contribute to their persistence. We observed that CML stem/progenitor cells (SPCs) produce tumor necrosis factor-α (TNF-α) in a kinase-independent fashion and at higher levels relative to their normal counterparts. We therefore investigated the role of TNF-α and found that it supports survival of CML SPCs by promoting nuclear factor κB/p65 pathway activity and expression of the interleukin 3 and granulocyte/macrophage-colony stimulating factor common β-chain receptor. Furthermore, we demonstrate that in CML SPCs, inhibition of autocrine TNF-α signaling via a small-molecule TNF-α inhibitor induces apoptosis. Moreover TNF-α inhibition combined with nilotinib induces significantly more apoptosis relative to either treatment alone and a reduction in the absolute number of primitive quiescent CML stem cells. These results highlight a novel survival mechanism of CML SPCs and suggest a new putative therapeutic target for their eradication.

AHI-1: a novel signaling protein and potential therapeutic target in human leukemia and brain disorders

Progress in the understanding of the molecular and cellular mechanisms of human cancer, including human leukemia and lymphomas, has been spurred by cloning of fusion genes created by chromosomal translocations or by retroviral insertional mutagenesis; a number of oncogenes and tumor suppressors involved in development of a number of malignancies have been identified in this manner. The BCR-ABL fusion gene, originating in a multipotent hematopoietic stem cell, is the molecular signature of chronic myeloid leukemia (CML). Discovery of this fusion gene has led to the development of one of the first successful targeted molecular therapies for cancer (Imatinib). It illustrates the advances that can result from an understanding of the molecular basis of disease. However, there still remain many as yet unidentified mutations that may influence the initiation or progression of human diseases. Thus, identification and characterization of the mechanism of action of genes that contribute to human diseases is an important and opportune area of current research. One promising candidate as a potential therapeutic target is Abelson helper integration site-1(Ahi-1/AHI-1) that was identified by retroviral insertional mutagenesis in murine models of leukemia/lymphomas and is highly elevated in certain human lymphoma and leukemia stem/progenitor cells. It encodes a unique protein with a SH3 domain, multiple SH3 binding sites and a WD40-repeat domain, suggesting that the normal protein has novel signaling activities. A new AHI-1-BCR-ABL-JAK2 interaction complex has recently been identified and this complex regulates transforming activities and drug resistance in CML stem/progenitor cells. Importantly, AHI-1 has recently been identified as a susceptibility gene involved in a number of brain disorders, including Joubert syndrome. Therefore, understanding molecular functions of the AHI-1 gene could lead to important and novel insights into disease processes involved in specific types of diseases. Ultimately, this knowledge will set the stage for translation into new and more effective diagnostic and treatment strategies.

Basic concepts of inflammation and its role in carcinogenesis

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

Predictors of response to extracorporeal photopheresis in advanced mycosis fungoides and Sézary syndrome

BACKGROUND

Extracorporeal photopheresis (ECP) has been utilized for more than 20 years to treat cutaneous T-cell lymphoma (CTCL), but a clinical response can take up to 9 months to manifest. This study was undertaken to determine whether clinical features, laboratory values, cytokine levels, or gene expression levels of tumor markers are useful to predict the subsequent response to ECP in CTCL patients with blood involvement.

METHODS

Twenty-one patients with CTCL treated with ECP as monotherapy for at least 6 months were retrospectively identified. Laboratory and clinical data and blood obtained at baseline, 3, and 6 months of treatment were used for analysis.

RESULTS

In pretreatment blood specimens, a lower percentage of Sézary cells and a higher absolute eosinophil count were associated with a favorable clinical response. Clinical evidence of an early response after 3 months of ECP did not reliably predict a favorable response at 6 months or beyond. Comparison of cytokines, gene transcripts, and other laboratory measures of disease did not correlate with the subsequent clinical response, although lactate dehydrogenase levels tended to decrease progressively in ECP-responsive cases and increase progressively in ECP-non-responsive cases. Additionally, serum levels of TNF-alpha significantly increased from baseline to 6 months of ECP, but was not found to correlate with the clinical response.

CONCLUSIONS

Although we found that increased eosinophils and decreased percentage of Sézary cells were associated with a favorable clinical response to ECP, we were not able to identify the predictors of ECP response within the first 3 months of treatment.

Deoxycholate induces COX-2 expression via Erk1/2-, p38-MAPK and AP-1-dependent mechanisms in esophageal cancer cells

Background

The progression from Barrett's metaplasia to adenocarcinoma is associated with the acquirement of an apoptosis-resistant phenotype. The bile acid deoxycholate (DCA) has been proposed to play an important role in the development of esophageal adenocarcinoma, but the precise molecular mechanisms remain undefined. The aim of this study was to investigate DCA-stimulated COX-2 signaling pathways and their possible contribution to deregulated cell survival and apoptosis in esophageal adenocarcinoma cells.

Methods

Following exposure of SKGT-4 cells to DCA, protein levels of COX-2, MAPK and PARP were examined by immunoblotting. AP-1 activity was assessed by mobility shift assay. DCA-induced toxicity was assessed by DNA fragmentation and MTT assay.

Results

DCA induced persistent activation of the AP-1 transcription factor with Fra-1 and JunB identified as the predominant components of the DCA-induced AP-1 complex. DCA activated Fra-1 via the Erk1/2- and p38 MAPK while Erk1/2 is upstream of JunB. Moreover, DCA stimulation mediated inhibition of proliferation with concomitant low levels of caspase-3-dependent PARP cleavage and DNA fragmentation. Induction of the anti-apoptotic protein COX-2 by DCA, via MAPK/AP-1 pathway appeared to balance the DCA mediated activation of pro-apoptotic markers such as PARP cleavage and DNA fragmentation. Both of these markers were increased upon COX-2 suppression by aspirin pretreatment prior to DCA exposure.

Conclusion

DCA regulates both apoptosis and COX-2-regulated cell survival in esophageal cells suggesting that the balance between these two opposing signals may determine the transformation potential of DCA as a component of the refluxate.

The role of NF-kappaB in lymphoid malignancies

Nuclear Factor kappaB (NF-kappaB) transcription factors are central regulators of lymphocyte proliferation, survival and development. Although normally subject to tight control, constitutive activation of NF-kappaB promotes inappropriate lymphocyte survival and proliferation, and is recognised as key pathological feature in various lymphoid malignancies. Inhibition of NF-kappaB may be an attractive therapeutic approach in these diseases. This review focuses on the mechanisms and functional consequences of NF-kappaB activation in lymphoid malignancies and potential therapeutic strategies for inhibition of NF-kappaB.

Variant-specific patterns and humoral regulation of HP1 proteins in human cells and tissues

We have examined the occurrence and distribution of HP1α and HP1β under in vivo, ex vivo and in vitro conditions. Consistent with a non-essential role in heterochromatin maintenance, both proteins are diminished or undetectable in several types of differentiated cells and are universally downregulated during erythropoiesis. Variant-specific patterns are observed in almost all human and mouse tissues examined. Yet, the most instructive example of HP1 plasticity is observed in the lymph nodes, where HP1α and HP1β exhibit regional patterns that are exactly complementary to one another. Furthermore, whereas HP1α shows a dispersed sub-nuclear distribution in the majority of peripheral lymphocytes, it coalesces into large heterochromatic foci upon stimulation with various mitogens and IL-2. The effect of inductive signals on HP1α distribution is reproduced by coculture of immortalized T- and B-cells and can be confirmed using specific markers. These complex patterns reveal an unexpected plasticity in HP1 variant expression and strongly suggest that the sub-nuclear distribution of HP1 proteins is regulated by humoral signals and microenvironmental cues.

Inflammation and cancer: How hot is the link?

Although inflammation has long been known as a localized protective reaction of tissue to irritation, injury, or infection, characterized by pain, redness, swelling, and sometimes loss of function, there has been a new realization about its role in a wide variety of diseases, including cancer. While acute inflammation is a part of the defense response, chronic inflammation can lead to cancer, diabetes, cardiovascular, pulmonary, and neurological diseases. Several pro-inflammatory gene products have been identified that mediate a critical role in suppression of apoptosis, proliferation, angiogenesis, invasion, and metastasis. Among these gene products are TNF and members of its superfamily, IL-1alpha, IL-1beta, IL-6, IL-8, IL-18, chemokines, MMP-9, VEGF, COX-2, and 5-LOX. The expression of all these genes are mainly regulated by the transcription factor NF-kappaB, which is constitutively active in most tumors and is induced by carcinogens (such as cigarette smoke), tumor promoters, carcinogenic viral proteins (HIV-tat, HIV-nef, HIV-vpr, KHSV, EBV-LMP1, HTLV1-tax, HPV, HCV, and HBV), chemotherapeutic agents, and gamma-irradiation. These observations imply that anti-inflammatory agents that suppress NF-kappaB or NF-kappaB-regulated products should have a potential in both the prevention and treatment of cancer. The current review describes in detail the critical link between inflammation and cancer.

Evidence for reprogramming global gene expression during zinc deficiency in the HUT-78 cell line

OBJECTIVE

Investigations using cell lines, primary cells, animal models, and human subjects have provided data to indicate that zinc-deficient conditions affect immune functioning of myeloid and lymphoid cells. We hypothesized that zinc-deficient conditions alone may induce the expression of genes in lymphoid cells, which favor enhanced responses to myeloid molecules even in the absence of myeloid cells or myeloid factors. Our objective was to investigate the effects of low zinc-induced alterations in gene expression in a single lymphoid cell line in the absence of influences from growth factors and/or cytokines generated by other cell types also being affected by low zinc status.

METHODS

Microarray analysis of non-stimulated and phytohemagglutinin-p/phorbol 12-myristate 13-acetate-stimulated zinc-deficient and zinc-adequate human-derived HUT-78 (TH(0)) lymphoblasts was used to identify changes in gene expressions associated solely with zinc-deficient status in these cells.

RESULTS

Overall, gene expression for molecules that would increase T-lymphocyte response to signals from myeloid cells such as cytokine receptors and selected adhesion molecules were upregulated, whereas those associated with T-lymphocyte-directed immune functions, interleukin-2 and interleukin-6 receptors, the cytokine interleukin-4, and zinc finger transcription factors were downregulated. Analysis of selected data obtained from healthy, but mildly zinc-deficient human subjects corroborated observations obtained from low zinc-altered gene expression in HUT-78 cells.

CONCLUSION

These data provide evidence for a shift in gene expression of molecules that would increase lymphoid responses to myeloid driven pathways during periods of zinc deficiency even in the absence of myeloid-derived stimuli.

Caffeic acid phenethyl ester modulates Helicobacter pylori-induced nuclear factor-kappa B and activator protein-1 expression in gastric epithelial cells

Caffeic acid phenethyl ester (CAPE), an active component of propolis from honeybee hives (honeybee resin), has anti-inflammatory, anti-carcinogenic and anti-bacterial properties. This study was designed to investigate the anti-inflammatory effects of CAPE on Helicobacter pylori-induced NF-kappaB and AP-1 in the gastric epithelial cell line AGS. Electrophoretic mobility shift assay was used to measure NF-kappaB- and AP-1-DNA binding activity. Western blotting was used to detect IkappaB-alpha and COX-2 expression in AGS cells cocultured with H. pylori. The antiproliferative effect of CAPE was measured by MTT assay. Our results showed that caffeic phenethyl ester inhibits H. pylori-induced NF-kappaB and AP-1 DNA-binding activity in a dose (0.1-25 microg ml(-1) approximately 0.35-88 microM) and time- (15-240 min) dependent manner in AGS cells. Maximum inhibition by CAPE was observed at concentrations of 25 microg ml(-1) ( approximately 88 microM) CAPE prevented H. pylori- and cytokine-induced degradation of IkappaB-alpha protein. Pretreatment of AGS cells with CAPE also blocked cytokine- and mitogen-induced NF-kappaB and AP-1 expression. Furthermore, CAPE suppressed H. pylori-induced cell proliferation and production of the cytokines TNF-alpha and IL-8. In addition, CAPE blocked H. pylori-induced COX-2 expression. The inhibition of such transcription by CAPE could result in suppression of many genes during H. pylori-induced inflammation, and also provide new insights into the anti-cancer and anti-inflammatory properties of CAPE.

Evidence for an oncogenic role of AHI-1 in Sezary syndrome, a leukemic variant of human cutaneous T-cell lymphomas

Ahi-1 (Abelson helper integration site 1) is a novel gene frequently activated by provirus insertional mutagenesis in murine leukemias and lymphomas. Its involvement in human leukemogenesis is demonstrated by gross perturbations in its expression in human leukemia cells, particularly in cutaneous T-cell lymphoma cell lines where increases in AHI-1 transcripts of 40-fold are seen. To test directly whether deregulated expression of AHI-1 contributes to their transformed properties, knockdown of AHI-1 expression in Hut78 cells, a cell line derived from a patient with Sezary syndrome (SS), was performed using retroviral-mediated RNA interference. Retroviral-mediated suppression specifically inhibited expression of AHI-1 and its isoforms in transduced cells by 80% and also reduced autocrine production of interleukin (IL)-2, IL-4 and tumor necrosis factor-alpha (TNFalpha) by up to 85%. It further significantly reduced their growth factor independence in vitro and the ability to produce tumors in immunodeficient mice. Interestingly, aberrant expression of AHI-1, particularly truncated isoforms, was present in CD4+CD7- Sezary cells from some patients with SS. Elevated expression of IL-2 and TNFalpha was also found in these cells. These findings provide strong evidence of the oncogenic activity of AHI-1 in human leukemogenesis and demonstrate that its deregulation may contribute to the development of SS.

Requirement of the human T-cell leukemia virus (HTLV-1) tax-stimulated HIAP-1 gene for the survival of transformed lymphocytes

Human T cell leukemia virus type 1 (HTLV-1), the cause of adult T cell leukemia (ATL), induces clonal expansion of infected T-cells in nonleukemic individuals and immortalizes T cells in vitro. The resistance against apoptotic stimuli of these cells hints at a viral survival function in addition to a proliferation-stimulating activity. Here we describe the up-regulation of the antiapoptotic HIAP-1/CIAP-2 gene as a consistent phenotype of HTLV-1-transformed and ATL-derived cultures and its stimulation by the viral oncoprotein Tax. Cotransfections revealed a 60-fold increase of HIAP-1 promoter activity mediated by Tax mainly via nuclear factor-kappaB (NF-kappaB) activation. To address the relevance of virally increased HIAP-1 levels for the survival of HTLV-1-transformed cells, its expression was RNA interference (RNAi) suppressed using a lentiviral transduction system. This resulted in a dramatic reduction of cell growth, a strong induction of apoptosis rates, and increased caspases 3/7 activity, which is known to be suppressed by HIAP-1. Thus, the Tax-mediated HIAP-1 overexpression is required to suppress endogenous apoptosis and, therefore, is essential for the survival of HTLV-1-transformed lymphocytes. Moreover, this points to HIAP-1 as an important target of the HTLV-1-mediated NF-kappaB activation.

Low pH and Helicobacter pylori increase nuclear factor kappa B binding in gastric epithelial cells: a common pathway for epithelial cell injury?

Helicobacter pylori infection results in peptic ulceration and chronic gastritis through mechanisms which are not fully elucidated. Live H. pylori activate the pro-inflammatory transcription factor NF-kappaB in gastric epithelial cells. Patients may have peptic ulcer disease in the absence of H. pylori infection; therefore other factors contribute to the inflammatory process. Maximal acid output in patients with H. pylori infection and duodenal ulceration is significantly increased indicating a role for acid in the pathogenesis of mucosal ulceration. The effect of low pH on NF-kappaB activation in gastric epithelial cells has not been studied. Human gastric epithelial cells (AGS) were exposed to a range of pH changes in the presence or absence of H. pylori. NF-kappaB DNA-binding and cytosolic IkappaB-alpha were measured using electrophoretic mobility shift assay and Western blotting. NF-kappaB DNA-binding in gastric epithelial cells dramatically increased when the pH of the culture medium decreased. Increases in NF-kappaB nuclear binding were paralleled by decreasing amounts of cytosolic IkappaB-alpha. These findings were similar but less potent than those observed when cells were exposed to H. pylori. Low pH resulted in enhancement of H. pylori-induced NF-kappaB nuclear binding. DNA binding of NF-kappaB activation secondary to low pH was attenuated by PD98059 but not by SB203580. Similar to H. pylori, low pH potently and independently augments NF-kappaB nuclear binding in AGS cells and such activation appears to be mediated through MEK1-dependant signaling pathways.

Biochemical effects of KH 1060 and anti-TNF monoclonal antibody on human peripheral blood mononuclear cells

The aim of this study was to investigate whether the vitamin D analogue KH 1060 could exert a suppressive action on Tumor necrosis factor-alpha (TNF-alpha). The chimeric anti-TNF-alpha monoclonal antibody (anti-TNF), alone or in combination with KH 1060, was also used. KH 1060 (0.01, 0.1, 1 nM) significantly inhibited cell proliferation, determined after 5 days by [3H]thymidine incorporation, when peripheral blood mononuclear cells (PBMC), obtained from healthy subjects, were stimulated with phytohaemagglutinin (PHA) and incubated for 24 h in the absence and in the presence of lipopolysaccharide (LPS). In the same experimental conditions, anti-TNF exerted a significant inhibition on PBMC proliferation, at the lowest doses (0.001, 0.01 microg/ml) in the absence of LPS, and at 0.001, 1, 10 microg/ml in its presence. A synergistic inhibition was registered combining KH 1060 and anti-TNF, at well-defined concentrations. 0.1 nM KH 1060 produced a significant decrease in TNF-alpha levels, determined by ELISA, although less remarkable than in the presence of anti-TNF. This decrease was synergistic, associating 0.1 nM KH 1060 and 0.1 microg/ml anti-TNF. VDR protein levels were increased by 0.1 nM KH 1060, 0.1 microg/ml anti-TNF or their combination. The protein levels of two oncogenes, Bax and Bcl-2, remained unchanged, when PBMC were incubated with KH 1060, anti-TNF or their combination in the absence of LPS, while, in its presence, an increase was registered. The demonstrated anti-TNF-alpha effect of KH 1060 may suggest for this compound an immunosuppressive action and the possibility to synergistically act with other drugs.

Direct ANP inhibition of hypoxia-induced inflammatory pathways in pulmonary microvascular and macrovascular endothelial monolayers

Atrial natriuretic peptide (ANP) has been shown to reduce hypoxia-induced pulmonary vascular leak in vivo, but no explanation of a mechanism has been offered other than its vasodilatory and natriuretic actions. Recently, data have shown that ANP can protect endothelial barrier functions in TNF-alpha-stimulated human umbilical vein endothelial cells. Therefore, we hypothesized that ANP actions would inhibit pulmonary vascular leak by inhibition of TNF-alpha secretion and F-actin formation. Bovine pulmonary microvascular (MVEC) and macrovascular endothelial cell (LEC) monolayers were stimulated with hypoxia, TNF-alpha, or bacterial endotoxin (LPS) in the presence or absence of ANP, and albumin flux, NF-kappa B activation, TNF-alpha secretion, p38 mitogen-activated protein kinase (MAPK), and F-actin (stress fiber) formation were assessed. In Transwell cultures, ANP reduced hypoxia-induced permeability in MVEC and TNF-alpha-induced permeability in MVEC and LEC. ANP inhibited hypoxia and LPS increased NF-kappa B activation and TNF-alpha synthesis in MVEC and LEC. Hypoxia decreased activation of p38 MAPK in MVEC but increased activation of p38 MAPK and stress fiber formation in LEC; TNF-alpha had the opposite effect. ANP inhibited an activation of p38 MAPK in MVEC or LEC. These data indicate that in endothelial cell monolayers, hypoxia activates a signal cascade analogous to that initiated by inflammatory agents, and ANP has a direct cytoprotective effect on the pulmonary endothelium other than its vasodilatory and natriuretic properties. Furthermore, our data show that MVEC and LEC respond differently to hypoxia, TNF-alpha-stimulation, and ANP treatment.

Nuclear factor-kappaB: a friend or a foe in cancer?

Nuclear transcription factor NF-kappaB, initially discovered as a factor in the nucleus of B cells that binds to the enhancer of the kappa light chain of immunoglobulin, has since been shown to be expressed ubiquitously in the cytoplasm of all cell types, conserved from Drosophila to man. It translocates to the nucleus only when activated, where it regulates the expression of over 200 genes that control the immune system, growth, and inflammation. The dysregulation of NF-kappaB can mediate a wide variety of diseases including cancer. Whether NF-kappaB activation is beneficial or harmful for cancer is controversial. The development of novel therapeutics targeting NF-kappaB requires full understanding of its role in pathology and physiology. The current review is an attempt to describe two sides of the NF-kappaB coin; viz, as a friend and as a foe.

Nuclear factor-kappaB: the enemy within

Numerous lines of investigation suggest that nuclear factor NF-kappaB, a proinflammatory transcription factor, could promote tumorigenesis. Various inflammatory agents, carcinogens, tumor promoters, and the tumor microenvironment activate NF-kappaB. NF-kappaB proteins themselves and proteins regulated by it have been linked to cellular transformation, proliferation, apoptosis suppression, invasion, angiogenesis, and metastasis. Constitutively activated NF-kappaB is common in wide variety of tumors. Furthermore, there exists genetic evidence that NF-kappaB mediates tumorigenesis. Thus, suppression of NF-kappaB activation should be effective in the prevention and treatment of cancer.

Nuclear factor-kappaB does not mediate the inhibitory effects of dexamethasone on granulocyte-macrophage colony-stimulating factor expression

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) reporter constructs containing up to 3.3 kb of upstream promoter sequence were transiently transfected into both Jurkat and HUT78 human T-cell lines. In Jurkat cells, stimulation with phorbol 12-myristate 13-acetate (PMA) plus phytohemaglutinin (PHA) produced robust increases in reporter activity, whereas HUT78 cells showed low levels of reporter induction attributable to constitutive nuclear factor (NF)-kappaB activity. Following mutation of either the proximal NF-kappaB site (-85/-76) or the activator protein1 (AP-1) motif within the conserved lymphokine element 0 (CLE0) site (-54/-31), reporter activity was markedly reduced in both cell lines. Despite this dependence on NF-kappaB and CLE0/AP-1, GM-CSF reporter activity was unaffected by dexamethasone in either cell line. Similarly, an NF-kappaB-dependent reporter was also not repressed by dexamethasone, yet GM-CSF release from HUT78 T cells was inhibited. These data therefore confirm a critical role for both NF-kappaB and CLE0 sites in GM-CSF promoter activation and indicate that NF-kappaB may not mediate glucocorticoid-dependent repression of GM-CSF in these cells.

Secretion of cytokines and growth factors as a general cause of constitutive NFkappaB activation in cancer

The constitutive activation of nuclear factor kappaB (NFkappaB) helps a variety of tumors to resist apoptosis and desensitizes them to chemotherapy, but the causes are still largely unknown. We have analysed this phenomenon in eight mutant cell lines derived from human 293 cells, selected for NFkappaB-dependent expression of a marker gene, and also in seven tumor-derived cell lines. Conditioned media from all of these cells stimulated the activation of NFkappaB (up to 30-fold) in indicator cells carrying an NFkappaB-responsive reporter. Therefore, secretion of extracellular factors as the cause of constitutive activation seems to be general. The mRNAs encoding several different cytokines and growth factors were greatly overexpressed in the tumor and mutant cells. The pattern of overexpression was distinct in each cell line, indicating that the phenomenon is complex. Two secreted factors whose roles in the constitutive activation of NFkappaB are not well defined were investigated further as pure proteins: transforming growth factor beta2 (TGFbeta2) and fibroblast growth factor 5 (FGF5) were both highly expressed in some mutant clones and tumor cell lines, each activated NFkappaB alone, and the combination was synergistic. Our data indicate that a group of different factors, expressed at abnormally high levels, can contribute singly and synergistically to the constitutive activation of NFkappaB in all of the mutant and tumor cell lines we studied. Since several NFkappaB target genes encode secreted proteins that induce NFkappaB, autocrine loops are likely to be ubiquitously important in the constitutive activation of NFkappaB in cancer. We provide the first evidence of the general, complex, and synergistic activation of NFkappaB in tumor and mutant cell lines through the action of secreted factors and suggest that the same explanation is likely for the constitutive activation of NFkappaB in cancers.

T Cell-Intrinsic Expression of c-Rel Regulates Th1 Cell Responses Essential for Resistance to Toxoplasma gondii

The ability of many microbial and inflammatory stimuli to activate members of the Rel/NF-kappaB family of transcription factors is associated with the regulation of innate and adaptive responses required to control infection. Individual family members play distinct roles during different infectious and inflammatory responses. For example, c-Rel is essential for the production of IL-12 in response to LPS, but dispensable for IL-12 production in response to Toxoplasma Ag. To assess the role of c-Rel during immunity to the intracellular pathogen Toxoplasma gondii, wild-type (WT) and c-Rel(-/-) mice were infected with Toxoplasma and the immune response was analyzed. c-Rel(-/-) mice developed severe toxoplasmic encephalitis with increased numbers of parasites compared with WT controls and succumbed to infection within 5-8 wk. Although increased susceptibility of c-Rel(-/-) mice was associated with decreased T cell activation, proliferation, and production of IFN-gamma, these mice were able to generate Th1 effector cells that were present in the brain during chronic infection. In vitro mixing studies using WT and c-Rel(-/-) dendritic cells and WT and c-Rel(-/-) TCR transgenic T cells indicated that c-Rel(-/-) dendritic cells are defective in their ability to stimulate T cell responses. However, when c-Rel(-/-) T cells were transferred into T cell-deficient hosts, early defects in T cell activation, proliferation, and IFN-gamma production persisted, and these mice remained susceptible to infection. Together, these studies indicate that although c-Rel is an important regulator of innate immune responses, it also plays an important role in optimization and maintenance of adaptive T cell responses during infection.

Map kinase signaling pathways and hematologic malignancies

Mitogen-activated protein (Map) kinases are widely expressed serine-threonine kinases that mediate important regulatory signals in the cell. Three major groups of Map kinases exist: the p38 Map kinase family, the extracellular signal-regulated kinase (Erk) family, and the c-Jun NH2-terminal kinase (JNK) family. The members of the different Map kinase groups participate in the generation of various cellular responses, including gene transcription, induction of cell death or maintenance of cell survival, malignant transformation, and regulation of cell-cycle progression. Depending on the specific family isoform involved and the cellular context, Map kinase pathways can mediate signals that either promote or suppress the growth of malignant hematopoietic cells. Over the last few years, extensive work by several groups has established that Map kinase pathways play critical roles in the pathogenesis of various hematologic malignancies, providing new molecular targets for future therapeutic approaches. In this review, the involvement of various Map kinase pathways in the pathophysiology of hematologic malignances is summarized and the clinical implications of the recent advances in the field are discussed.

The role of VEGF in normal and neoplastic hematopoiesis

VEGF is a secreted growth factor that mediates its biological effects by binding to two transmembrane tyrosine kinase receptors, VEGFR-1 and VEGFR-2. The VEGF/receptor signaling system is involved in the regulation of two fundamental processes in vertebrates: the formation of blood vessels (angiogenesis) and of blood cells (hematopoiesis). Hematopoietic stem cells, capable of giving rise to all blood cell lineages, are often found in clusters with endothelial cells, the key cell type involved in the formation of blood vessels. Despite such proximity of VEGF-responsive cells, hematopoiesis occurs independently of neoangiogenesis in the adult bone marrow, suggesting that VEGF regulates the two processes by different mechanisms. In support of this hypothesis, the recently identified autocrine loop by which VEGF may control hematopoietic stem cell survival and repopulation, is fundamentally different from its paracrine effects regulating angiogenesis. Furthermore, coexpression of VEGF and its receptors, the prerequisite for autocrine loops, is frequently found in lymphomas and myelomas, suggesting that autocrine loops also play a role in hematological malignancies. Several therapeutic strategies blocking VEGF or VEGF-induced signaling are currently being investigated for the treatment of neoplastic diseases. They differ in their potential to interfere with the autocrine or paracrine effector functions of VEGF during angiogenesis, hematopoiesis, and tumor cell proliferation, properties which may ultimately determine their therapeutic potential.

Zinc enhances the expression of interleukin-2 and interleukin-2 receptors in HUT-78 cells by way of NF-kappaB activation

Production of interleukin (IL)-2 is decreased in zinc-deficient human beings, and zinc is essential to IL-2-mediated T-cell activation. We used a human Th(0) malignant lymphoblastoid cell line, HUT-78, to study the effect of zinc on IL-2 production in PHA/PMA activated T-cells. In zinc-deficient cells, the gene expression of IL-2 was decreased by 50% compared with that in zinc-sufficient cells. The effect of zinc was specific and at the transcriptional level. We also showed a significant effect of zinc on the gene expression of IL-2 receptors alpha and beta. Binding of NF-kappaB (a zinc-dependent transcription factor) to DNA was decreased in zinc-deficient cells. Using transfection of expression vectors of anti-sense NF-kappaB p105 (precursor of NF-kappaB p50) in cells, we showed that a decrease in gene expression of IL-2 and IL-2 Ralpha may be partly due to decreased activation of NF-kappaB in zinc-deficient cells. Our studies demonstrate, for the first time, the role of zinc in gene expression of IL-2 and its receptors in HUT-78 cells. We also document that the binding of NF-kappaB to DNA was adversely affected, thereby decreasing the gene expression of IL-2 and IL-2 Ralpha in zinc-deficient HUT-78 cells.

Nuclear transcription factor-kappaB as a target for cancer drug development

Nuclear factor kappa B (NF-kappaB) is a family of inducible transcription factors found virtually ubiquitously in all cells. Since its discovery by Sen and Baltimore in 1986, much has been discovered about its mechanisms of activation, its target genes, and its function in a variety of human diseases including those related to inflammation, asthma, atherosclerosis, AIDS, septic shock, arthritis, and cancer. Due to its role in a wide variety of diseases, NF-kappaB has become one of the major targets for drug development. Here, we review our current knowledge of NF-kappaB, the possible mechanisms of its activation, its potential role in cancer, and various strategies being employed to target the NF-kappaB signaling pathway for cancer drug development.

Oxidative stress induces apoptosis in C6 glioma cells: involvement of mitogen-activated protein kinases and nuclear factor kappa B

Excessive oxidative stress has been implicated in the induction of cell death in a variety of neurodegenerative diseases. In the present study, hydrogen peroxide (H2O2)-induced cell death in rat C6 glioma cells was used as a model system for studying the molecular events associated with oxidative stress-induced cell death in glial cells. We demonstrate that exposure of C6 glioma cells to H2O2 results in apoptotic cell death in a concentration-dependent manner, and caused activation of a member of the caspase-3-like family of proteases resulting in cleavage of the DNA repair enzyme poly(ADP-ribose)polymerase, PARP. Furthermore, H2O2 induced a transient activation of the transcription factor, nuclear factor kappa B (NF(Kappa)B). Pre-treatment of cells with the antioxidant N-acetylcysteine, (NAC), prevented both the activation of NF(Kappa)B and the induction of apoptosis by H2O2, suggesting a possible role for this transcription factor in oxidant-induced apoptosis in glial cells. Exposure of the cells to H2O2 led to transient activation of both c-Jun N-terminal kinase (JNK) and p38 kinase but has no effect on extracellular regulated kinase (ERK) activity. Inhibition of p38 by SB203580 did not protect the cells against H2O2-induced apoptosis suggesting that activation of p38 is not essential for H2O2-mediated cell death in C6 glioma cells.

Cutting edge: protein kinase C beta expression is critical for export of Il-2 from T cells

Protein kinase C (PKC) plays an integral part in T cell activation and IL-2 secretion. We investigated the role of a particular PKC isoform, PKCbeta, in IL-2 production and secretion. The T cell lymphoma line HuT 78 secretes IL-2 in response to the phorbol ester PMA. A PKCbeta-deficient clone of HuT 78, K-4, did not secrete IL-2 in response to PMA stimulation. As assessed by RT-PCR, K-4 expressed mRNA for IL-2 following PMA activation, and intracellular IL-2 protein was detected by immunofluorescence. An enhanced green fluorescent protein-linked PKCbeta construct was microinjected into K-4 cells, which were then stimulated with PMA; those cells that expressed PKCbeta could secrete IL-2, as determined by an in situ immunofluorescent assay. This study demonstrates that PKCbeta is not necessary for transcription of the IL-2 gene or translation of mRNA to protein, but that expression of this PKC isoform is critical to the export of IL-2 molecules from T cells.

Activation of p38 mitogen-activated protein kinase is required for tumor necrosis factor-alpha -supported proliferation of leukemia and lymphoma cell lines

To elucidate mechanisms of tumor necrosis factor alpha (TNF-alpha)-induced proliferation of a number of human leukemia and lymphoma cell lines, we examined the role of p38 mitogen-activated protein kinase (MAPK) in TNF-alpha signaling in Mo7e and Hut-78 cells. TNF-alpha-dependent p38 MAPK activation was detected in both Mo7e and Hut-78 cells and was blocked by the p38 MAPK inhibitor, SB203580. Ablation of p38 MAPK activity by SB203580 abrogated TNF-alpha-induced Mo7e cell proliferation and TNF-alpha-dependent autocrine growth of Hut-78. As we have shown previously that activation of the nuclear factor kappaB (NF-kappaB) is also required for TNF-alpha-induced Mo7e cell proliferation, the involvement of p38 MAPK in NF-kappaB activation was assessed. SB203580 did not affect TNF-alpha-signaled nuclear translocation and DNA-binding activity of NF-kappaB, and inhibition of NF-kappaB function did not affect TNF-alpha-induced p38 MAPK activation, indicating that these events are not dependent on each other. However, SB203580 depressed the expression of NF-kappaB-dependent genes, as monitored by a kappaB-driven reporter gene. Our findings demonstrate that activation of both p38 MAPK and NF-kappaB plays a critical role in TNF-alpha-mediated survival and proliferation of human leukemia and lymphoma cells, and p38 MAPK acts at least in part by facilitating the transcriptional activation function of NF-kappaB.

Liposomal delivery of purified inhibitory-kappaBalpha inhibits tumor necrosis factor-alpha-induced human vascular smooth muscle proliferation

Vessel injury results in the elaboration of various cytokines, including tumor necrosis factor-alpha (TNF-alpha), which may influence vascular smooth muscle cell (VSMC) function and contribute to atherogenesis. We tested the hypothesis that TNF-alpha-induced VSMC proliferation requires activation of the transcription factor nuclear factor-kappaB (NF-kappaB), which could be prevented by delivery of the NF-kappaB inhibitory peptide, IkappaBalpha. TNF-alpha induced concentration-dependent human VSMC proliferation, and neutralizing antibody to interleukin-6 reduced TNF-alpha-induced VSMC proliferation by 65%. In TNF-alpha-stimulated VSMCs, there was a 3-fold increase in NF-kappaB-dependent luciferase reporter activity that was associated with degradation of IkappaBalpha. To determine an essential role for NF-kappaB in TNF-alpha-induced VSMC proliferation, recombinant IkappaBalpha was introduced into VSMCs via liposomal delivery. Under these conditions, TNF-alpha-induced NF-kappaB nuclear translocation and DNA binding were inhibited, NF-kappaB-dependent luciferase activity was reduced by 50%, there was no degradation of native IkappaBalpha detected, interleukin-6 production was reduced by 54%, and VSMC proliferation was decreased by 60%. In conclusion, the mitogenic effect of TNF-alpha on human arterial VSMCs is dependent on NF-kappaB activation and may be prevented by exogenously delivered IkappaBalpha. Furthermore, liposomal delivery of endogenous inhibitory proteins may represent a novel, therapeutically accessible method for selective transcriptional suppression in the response to vascular injury.

Interleukin-15 Is an Autocrine/Paracrine Viability Factor for Cutaneous T-Cell Lymphoma Cells

In this study we investigated the role of interleukin-15 (IL-15) in the immunobiology of cutaneous T-cell lymphoma (CTCL) cells. Using cell culture techniques, reverse transcriptase-polymerase chain reaction (RT-PCR), and immunhistochemistry we found that IL-15, like IL-7, is a growth factor for the Sézary cell line SeAx and that both cytokines prolonged the survival of malignant T cells directly isolated from Sézary syndrome (SS) patients. Both IL-15 and IL-7 were more potent than IL-2. IL-4 and IL-9, whose receptors share the same gamma chain with the receptors of IL-2, IL-7, and IL-15, did not sustain the growth of CTCL cells, indicating that signaling through the common gamma chain (γc) is not sufficient for continuous growth. IL-13 and tumor necrosis factor-α (TNF-α) had no effect. IL-7 and IL-15 also supported the growth of SeAx cells in the presence of the apoptosis inducing agents dexamethasone and retinoic acid. The analysis of patient Sézary cells and three CTCL cell lines by RT-PCR showed that all these cells expressed IL-15 mRNA, but only a few (25%) produced IL-7 mRNA. Immunohistological analyses of skin biopsy samples of SS and Mycosis fungoides patients showed immunoreactivity for IL-15 in basal cell layer keratinocytes and in the infiltrating lymphocytes. We conclude that IL-15 is a growth or viability factor for CTCL-derived cell lines or shortly cultivated Sézary cells. The findings that IL-15 mRNA can be detected in Sézary syndrome peripheral blood mononuclear cells and that the IL-15 protein is detected in skin sections from CTCL patients suggest that IL-15 plays an important role in the biology of CTCL.

Constitutive activation of NF-kappaB causes resistance to apoptosis in human cutaneous T cell lymphoma HuT-78 cells. Autocrine role of tumor necrosis factor and reactive oxygen intermediates

How tumor cells develop resistance to apoptosis induced by cytokines and chemotherapeutic agents is incompletely understood. In the present report, we investigated apoptosis induction by tumor necrosis factor (TNF) in two human T cell lines, Jurkat and HuT-78. While TNF inhibited the growth of Jurkat cells and activated caspase-3, it had no effect on HuT-78 cells. It was further found that HuT-78 cells constitutively expressed the nuclear transcription factor NF-kappaB. TNF activated NF-kappaB in Jurkat cells but not in HuT-78 cells. HuT-78 cells were also resistant to NF-kappaB activation induced by phorbol ester, H2O2, ceramide, endotoxin, and interleukin-1. Despite the presence of preactivated NF-kappaB, HuT-78 cells also expressed high levels of IkappaB-alpha, the inhibitory subunit of NF-kappaB and, unlike Jurkat cells, were resistant to TNF-induced degradation of IkappaB-alpha. Its half-life in HuT-78 cells was 12 h as opposed to 45 min in Jurkat cells. Antibodies against TNF blocked the constitutive activation of NF-kappaB and proliferation of HuT-78 cells but had no significant effect on Jurkat cells, suggesting an autocrine role for TNF. The antioxidant pyrrolidine dithiocarbamate also suppressed constitutive NF-kappaB activation and it reversed the cell's sensitivity to TNF-induced cytotoxicity and activation of caspase-3. Overall, these results suggest that constitutive activation of NF-kappaB, TNF, and prooxidant pathway in certain T cell lymphomas causes resistance to apoptosis, and this can be reversed by antioxidants.

Low environmental pH is responsible for the induction of nitric-oxide synthase in macrophages. Evidence for involvement of nuclear factor-kappaB activation

Stimulation of macrophages with endotoxin and/or cytokines is responsible for the expression of the inducible isoform of nitric oxide synthase (iNOS). Because macrophages are exposed to low pH within the microenvironment of inflammatory lesions, the potential role of acidic pH as an additional regulator of iNOS was investigated. Substitution of the culture medium of rat peritoneal macrophages at pH 7.4 with medium at pH 7.0 up-regulated iNOS activity, as reflected by a 2.5-fold increase in nitrite accumulation. The increase in iNOS activity was associated with a similar increase in iNOS mRNA expression that reflected an increase in iNOS mRNA synthesis rather than stability. Low environmental pH-induced iNOS gene transcription involved the activation of nuclear factor-kappaB (NF-kappaB) transcription factor since exposure of macrophages to low environmental pH both increased NF-kappaB binding activity in the nucleus and enhanced NF-kappaB-driven reporter gene expression. In addition, treatment of macrophages with pyrrolidine dithiocarbamate or n-acetyl-leucinyl-leucinyl-norleucinal, two drugs preventing NF-kappaB translocation to the nucleus, canceled low pH-induced nitrite accumulation. The overall mechanism required the synthesis of tumor necrosis factor alpha (TNFalpha). Indeed, 1) elevated TNFalpha bioactivity was observed in the medium of macrophages exposed to pH 7.0, and 2) incubation of macrophages with a neutralizing anti-TNFalpha antibody impaired both NF-kappaB activation and nitrite accumulation in response to acid challenge. In summary, exposure of macrophages to acidic microenvironment in inflammatory lesions leads to the up-regulation of iNOS activity through the activation of NF-kappaB.

Activation of the interleukin-10 gene in the human T lymphoma line HuT 78: identification and characterization of NF-kappa B binding sites in the regulatory region of the interleukin-10 gene

Interleukin-10 (IL-10) is a pleiotropic cytokine which has potent inhibitory effects on macrophages and T cells, and contributes to the regulation of proliferation and differentiation of B cells. Resting HuT 78, a T-cell line derived from a Sezary lymphoma, produced significant amounts of IL-10 compared with another T-cell line, Jurkat. To elucidate the mechanisms by which the IL-10 is expressed, we have analyzed their activity in human T-cell lines. We report here evidence that members of the family of transcription factors nuclear factor-kappa B (NF-kappa B)/Rel can specifically recognize 3 identical sequences located in the 5'-regulatory region of IL-10 gene in resting HuT 78 cells, whereas Jurkat cells expressed high levels of NF-kappa B consisting of p65 and p50 only upon activation with tumor necrosis factor-alpha (TNF-alpha). In HuT 78 cells, p50 was the major component in the NF-kappa B complexes. Exogenous TNF-alpha and the monoclonal antibody to TNF-alpha did not affect IL-10 production and constitutive NF-kappa B binding levels in HuT 78 cells. This study is the first demonstration of a role for NF-kappa B in the IL-10 gene expression, and suggests that its expression does not require TNF-alpha. These novel findings may account for the specific IL-10 gene expression in T cells.

Evidence for the Participation of Interleukin-2 (IL-2) and IL-4 in the Regulation of Autonomous Growth and Tumorigenesis of Transformed Cells of Lymphoid Origin

In the current study, we investigated the role of interleukin-2 (IL-2) and IL-4 as autocrine growth factors responsible for autonomous growth of four murine tumor cell lines: LSA, a radiation leukemia virus-induced T-cell lymphoma; EL-4, a chemically triggered T-cell lymphoma; PE-3T, a T-cell line that underwent spontaneous transformation ex vivo; and P815, a mastocytoma. All tumor cell lines screened constitutively expressed IL-2 receptor (IL-2R) and IL-4R genes. However, only LSA and PE-3T cells expressed IL-2 and IL-4 genes constitutively, whereas EL-4 and P815 tumor cells expressed only IL-4 but not IL-2. Monoclonal antibodies (MoAbs) against IL-2, IL-4, or a combination of these, as well as MoAbs against IL-2R significantly inhibited the proliferation of LSA but not that of other tumor cell lines ex vivo. To exclude the possibility that, in other tumor cell lines, the autocrine growth factor may interact with its receptor within the cell, the ability of antisense phosphorothioate oligonucleotides to inhibit the growth of the tumor cells was tested. The antisense phosphorothioate oligonucleotides specific for IL-2, IL-4, IL-2Rβ, or IL-2Rγ chains, added in culture, could markedly inhibit the growth of LSA but not that of the other tumor cell lines screened. Inasmuch as IL-2Rβ and IL-2Rγ subunits also serve as a component of the receptors for IL-4, IL-7, IL-9, and IL-15, the above data suggested that such cytokine redundancy was not responsible for autonomous growth of the other tumor cell lines. Addition of exogenous IL-2 or IL-4 to the tumor cell cultures caused significant enhancement in the proliferation of PE-3T cells, whereas other cell lines were either not significantly affected or slightly inhibited from growing. Interestingly, the LSA tumor growth in nude mice was significantly inhibited after treatment of these mice with a combination of MoAbs against IL-2 and IL-4. Together, our studies show for the first time that IL-2 and IL-4 may serve as autocrine growth factors in the autonomous proliferation of tumor cells, particularly those that are retrovirally induced. Second, some tumor cell lines, despite expressing certain cytokines and their receptors constitutively, may not depend exclusively on such factors for autocrine growth.

Alcohol and cytokine-inducible transcription factors

Cytokines, such as TNF alpha, modulate the behavior of many cells by regulating the expression of a wide array of genes. When a cytokine binds to its receptor on the cell surface, the receptor becomes activated and activates signal transduction cascades. These cascades typically involve a series of phosphorylation reactions that lead to sequential activation of various kinases. The targets of these kinases include DNA binding proteins that regulate the transcription of target genes. The activity of DNA binding proteins, such as c-Jun and NF-kappa B, titrates the transcriptional activity of cytokine-regulated genes. Both acute and chronic alcohol consumption of ethanol increase hepatic expression of TNF alpha. After acute ethanol consumption, this is associated with increased induction of several TNF-dependent regenerative events, including the activation of c-Jun and increased binding activity of NF-kappa B. However, chronic consumption of ethanol appears to impede TNF alpha signaling in the liver because it attenuates the increases in c-JUN activity and NF-kappa B binding, which normally follow partial hepatectomy. These results suggest that one mechanism by which ethanol influences liver cell behavior is by influencing local expression of TNF alpha and changing the activity of TNF-regulated transcription factors.

TNF2, a polymorphism of the tumour necrosis-alpha gene promoter, is a component of the celiac disease major histocompatibility complex haplotype

Celiac disease (CD) is an immune disease triggered by the cereal antigen gliadin, resulting in villous atrophy in the small intestine. Susceptibility to the development of CD is strongly influenced by genes in the major histocompatibility complex, in particular alleles of the DQ genes in the class II region. However recent evidence has suggested that the major histocompatibility complex (MHC) class III region may be linked to celiac disease independently of the class II region. Among the genes located in this area is TNF-alpha, which encodes the cytokine tumor necrosis factor-alpha which has a broad range of pro-inflammatory, immunomodulatory and catabolic activities. Therefore, aberrant expression of TNF-alpha could be important in the pathogenesis of MHC-associated immune disorders. A TNF-alpha variant with a polymorphism in its promoter region has been described and designated TNF2. TNF2 has been associated with a variety of MHC-linked diseases, including systemic lupus erythematosus, dermatitis herpetiformis and insulin-dependent diabetes mellitus (IDDM), as well as parasitic infections. TNF2 has previously been shown to be associated with the MHC haplotype HLA A1-B8-DR3-DQ2, which confers susceptibility to CD. We have analyzed the distribution of TNF2 alleles in a group of celiac patients (n = 52) compared to controls (n = 52) in an effort to evaluate its role, if any, in susceptibility to the condition. TNF2 has a frequency of 0.5000 (SE +/- 0.0490) in CD, compared to 0.1635 (+/- 0.0362) in a control sample (p < 10(-6)). Of 52 patients, 44 carried one or more TNF2 alleles. Analysis indicates that the distribution of TNF2 is best explained by assuming 100% allelic association between it and HLA-DQB1*0201 (frequency = 0.7791 +/- 0.0447). However, the number of TNF2 heterozygotes significantly exceeds expectations and measurements of linkage disequilibrium confirm that allelic associations spanning the DQ and TNF regions are strongly maintained in CD. Taken together, these results indicate that TNF2 may have a role in the pathogenesis of CD; however, since it is not an independent association, the possibility that TNF2 constitutes a passive component of the CD haplotype cannot be excluded.

Tumor necrosis factor alpha promotes nuclear localization of cytokine-inducible CCAAT/enhancer binding protein isoforms in hepatocytes

Hepatocytes were cultured in the presence of recombinant tumor necrosis factor (TNF) alpha or mutated TNF alpha peptides that specifically activate either p55 or p75 TNF receptors to determine if TNF alpha can activate cytokine-inducible CCAAT/enhancer binding protein (C/EBP) isoforms by post-transcriptional mechanisms that are initiated by TNF receptors. Within 5-10 min after treatment with any of these agents, nuclear concentrations of C/EBP beta and C/EBP delta double and remain 2-4-fold greater than control cultures for 30 min (p < 0.01). Consistent with these results, gel mobility shift assays demonstrate 3-fold increased nuclear C/EBP beta- and C/EBP delta-DNA binding activity in TNF alpha-treated cells, and immunocytochemistry confirms rapid redistribution of these C/EBP isoforms into the nucleus. In contrast, mRNA and whole cell protein concentrations of C/EBP beta and delta are not altered by TNF alpha exposure, and nuclear concentrations of another C/EBP isoform, C/EBP alpha, are decreased by 80%. This novel evidence that TNF alpha initiates post-transcriptional activation of cytokine-inducible C/EBP isoforms identifies a mechanism that enables hepatocytes to respond immediately to inflammatory stress.