Anti-rheumatic compound aurothioglucose inhibits tumor necrosis factor-alpha-induced HIV-1 replication in latently infected OM10.1 and Ach2 cells

Next Generation Gold Drugs and Probes: Chemistry and Biomedical Applications

The gold drugs, gold sodium thiomalate (Myocrisin), aurothioglucose (Solganal), and the orally administered auranofin (Ridaura), are utilized in modern medicine for the treatment of inflammatory arthritis including rheumatoid and juvenile arthritis; however, new gold agents have been slow to enter the clinic. Repurposing of auranofin in different disease indications such as cancer, parasitic, and microbial infections in the clinic has provided impetus for the development of new gold complexes for biomedical applications based on unique mechanistic insights differentiated from auranofin. Various chemical methods for the preparation of physiologically stable gold complexes and associated mechanisms have been explored in biomedicine such as therapeutics or chemical probes. In this Review, we discuss the chemistry of next generation gold drugs, which encompasses oxidation states, geometry, ligands, coordination, and organometallic compounds for infectious diseases, cancer, inflammation, and as tools for chemical biology via gold-protein interactions. We will focus on the development of gold agents in biomedicine within the past decade. The Review provides readers with an accessible overview of the utility, development, and mechanism of action of gold-based small molecules to establish context and basis for the thriving resurgence of gold in medicine.

Triphenylphosphine gold(I) derivatives promote antiviral effects against the Chikungunya virus

Herein a systematic series of four [AuLL']n+ n = 0, +1 complexes, where L = 1,3-bis(mesityl)imidazole-2-ylidene (IMes), or triphenylphosphine (PPh3), and L' = chloride, or 4-dimethylaminopyridine (DMAP), had their in vitro antiviral activity assessed against Chikungunya virus (CHIKV). The PPh3 derivatives inhibited viral replication by 99%, whereas the IMes derivatives about 50%. The lipophilicity of the PPh3 derivatives is higher than the IMes-bearing compounds, which can be related to their more prominent antiviral activities. The dissociation of DMAP is faster than chloride in solution for both IMes and PPh3 derivatives; however, it does not significantly affect their in vitro activities, showing a higher dependence on the nature of L rather than L' towards their antiviral effects. All complexes bind to N-acetyl-L-cysteine, with the Ph3P-bearing complexes coordinating at a faster rate to this amino acid. The binding constants to bovine serum albumin (BSA) are in the order of 104, slightly higher for the DMAP complexes in both PPh3 and IMes derivatives. Mechanistic investigations of the PPh3 complexes showed a ubiquitous protective effect of the compounds in the pre-treatment, early stages, and post-entry assays. The most significant inhibition was observed in post-entry activity, in which the complexes blocked viral replication in 99%, followed by up to 95% inhibition of the early stages of infection. Pre-treatment assays showed a 92% and 80% replication decrease for the chloride and DMAP derivatives, respectively. dsRNA binding assays showed a significant interaction of the compounds with dsRNA, an essential biomolecule to viral replication.

U1 and OM10.1. Myeloid Cell Lines as Surrogate Models of Reversible Proviral Latency

As already discussed for T cell lines, also myeloid cell lines as served as the earliest models of chronic HIV infection. They were particularly relevant in the late 1980s and early 1990s when most experimental in vitro infections were based on laboratory-adapted "T-cell tropic" strains of HIV-1, such as LAI/IIIB or others, that later were found to rely upon CXCR4 as coreceptor for viral entry in addition to CD4 as primary receptor. Although primary macrophages do express CXCR4 together with CD4, virus replication is much less efficient than that observed with CCR5-using "macrophage-tropic" strains, as discussed separately in this book. Although different myeloid cell lines have been used to generate models of chronic HIV-1 infection that could be used to investigate features of proviral reactivation, as reviewed in (Cassol et al. J Leukoc Biol 80:1018-1030, 2006), two cell lines in particular have been broadly used and will be here discussed: the U937-derived U1 and HL-60-derived OM-10.1.

Gold Metallodrugs to Target Coronavirus Proteins: Inhibitory Effects on the Spike-ACE2 Interaction and on PLpro Protease Activity by Auranofin and Gold Organometallics*

Gold complexes have a long tradition in medicine and for many examples antirheumatic, anticancer or anti-infective effects have been confirmed. Herein, we evaluated the lead compound Auranofin and five selected gold organometallics as inhibitors of two relevant drug targets of severe acute respiratory syndrome coronaviruses (SARS-CoV). The gold metallodrugs were effective inhibitors of the interaction of the SARS-CoV-2 spike protein with the angiotensin converting enzyme 2 (ACE2) host receptor and might thus interfere with the viral entry process. The gold metallodrugs were also efficient inhibitors of the papain-like protease (PLpro) of SARS-CoV-1 and SARS-CoV-2, which is a key enzyme in the viral replication. Regarding PLpro from SARS-CoV-2, the here reported inhibitors are among the very first experimentally confirmed examples with activity against this target enzyme. Importantly, the activity of the complexes against both PLpro enzymes correlated with the ability of the inhibitors to remove zinc ions from the labile zinc center of the enzyme. Taken together, the results of this pilot study suggest further evaluation of gold complexes as SARS-CoV antiviral drugs.

Platelet IκB kinase-β deficiency increases mouse arterial neointima formation via delayed glycoprotein Ibα shedding

OBJECTIVE

On the luminal surface of injured arteries, platelet activation and leukocyte-platelet interactions are critical for the initiation and progression of arterial restenosis. The transcription factor nuclear factor-κB is a critical molecule in platelet activation. Here, we investigated the role of the platelet nuclear factor-κB pathway in forming arterial neointima after arterial injury.

METHODS AND RESULTS

We performed carotid artery wire injuries in low-density lipoprotein receptor-deficient (LDLR(-/-)) mice with a platelet-specific deletion of IκB kinase-β (IKKβ) (IKKβ(fl/fl)/PF4(cre)/LDLR(-/-)) and in control mice (IKKβ(fl/fl)/LDLR(-/-)). The size of the arterial neointima was 61% larger in the IKKβ(fl/fl)/PF4(cre)/LDLR(-/-) mice compared with the littermate control IKKβ(fl/fl)/LDLR(-/-) mice. Compared with the control mice, the IKKβ(fl/fl)/PF4(cre)/LDLR(-/-) mice exhibited more leukocyte adhesion at the injured area. The extent of glycoprotein Ibα shedding after platelet activation was compromised in the IKKβ-deficient platelets. This effect was associated with a low level of the active form of A Disintegrin And Metalloproteinase 17, the key enzyme involved in mediating glycoprotein Ibα shedding in activated IKKβ-deficient platelets.

CONCLUSIONS

Platelet IKKβ deficiency increases the formation of injury-induced arterial neointima formation. Thus, nuclear factor-κB-related inhibitors should be carefully evaluated for use in patients after an arterial intervention.

Gene expression profiling of macrophages: implications for an immunosuppressive effect of dissolucytotic gold ions

Background

Gold salts has previously been used in the treatment of rheumatoid arthritis but have been replaced by biologicals such as TNF-α inhibitors. The mechanisms behind the anti-inflammatory effect of metallic gold ions are still unknown, however, recent data showed that charged gold atoms are released from pure metallic gold implants by macrophages via a dissolucytosis membrane, and that gold ions are taken up by local macrophages, mast cells and to some extent fibroblasts. These findings open the question of possible immunomodulatory effects of metallic gold and motivate efforts on a deeper understanding of the effect of metallic gold on key inflammatory cells as macrophages.

Methods

Human macrophage cells (cell line THP-1) were grown on gold foils and intracellular uptake was analysed by autometallography. The impact of phagocytised gold ions on viability of THP-1 cells was investigated by trypan blue staining and TUNEL assay. The global gene expression profile of THP-1 cells after incorporation of gold ions was studied using microarray analysis comprising approximately 20,000 genes. The gene expression data was confirmed by measurement of secreted proteins.

Results

Autometallography showed intracellular uptake of gold ions into THP-1 cells. No significant effect on viability of THP-1 cells was demonstrated. Our data revealed a unique gene expression signature of dissolucytotic THP-1 cells that had taken up gold ions. A large number of regulated genes were functionally related to immunomodulation. Gold ion uptake induced downregulation of genes involved in rheumatoid arthritis such as hepatocyte growth factor, tenascin-C, inhibitor of DNA binding 1 and 3 and matrix metalloproteinase 13.

Conclusion

The data obtained in this study offer new insights into the mode of action of gold ions and suggest for the investigation of effects on other key cells and a possible future role of metallic gold as implants in rheumatoid arthritis or other inflammatory conditions.

Glutathione and glutaredoxin act as a backup of human thioredoxin reductase 1 to reduce thioredoxin 1 preventing cell death by aurothioglucose

Thioredoxin reductase 1 (TrxR1) in cytosol is the only known reductant of oxidized thioredoxin 1 (Trx1) in vivo so far. We and others found that aurothioglucose (ATG), a well known active-site inhibitor of TrxR1, inhibited TrxR1 activity in HeLa cell cytosol but had no effect on the viability of the cells. Using a redox Western blot analysis, no change was observed in redox state of Trx1, which was mainly fully reduced with five sulfhydryl groups. In contrast, auranofin killed cells and oxidized Trx1, also targeting mitochondrial TrxR2 and Trx2. Combining ATG with ebselen gave a strong synergistic effect, leading to Trx1 oxidation, reactive oxygen species accumulation, and cell death. We hypothesized that there should exist a backup system to reduce Trx1 when only TrxR1 activity was lost. Our results showed that physiological concentrations of glutathione, NADPH, and glutathione reductase reduced Trx1 in vitro and that the reaction was strongly stimulated by glutaredoxin1. Simultaneous depletion of TrxR activity by ATG and glutathione by buthionine sulfoximine led to overoxidation of Trx1 and loss of HeLa cell viability. In conclusion, the glutaredoxin system and glutathione have a backup role to keep Trx1 reduced in cells with loss of TrxR1 activity. Monitoring the redox state of Trx1 shows that cell death occurs when Trx1 is oxidized, followed by general protein oxidation catalyzed by the disulfide form of thioredoxin.

Effects of dissolucytotic gold ions on recovering brain lesions

Recent experimental research has shown that metallic gold releases charged gold atoms when placed intracerebrally and that the liberated gold ions affect inflammation in the brain. The observations suggest that metallic gold can be used as a safe suppressor of inflammation in the central nervous system.

Tetra-chloro-(bis-(3,5-dimethylpyrazolyl)methane)gold(III) chloride: An HIV-1 reverse transcriptase and protease inhibitor

The title compound ([3,5-Me(2)bpzaH(2)][AuCl(4)]Cl, 1) (Me(2)bpza=bis(3,5-dimethylpyrazolyl)acetic acid), was prepared by reacting H[AuCl(4)] with 3,5-Me(2)bpza; and spectroscopically and structurally characterized. In the solid state structure of 1, the pyrazolyl ligand is doubly protonated to form two strong charge assisted hydrogen bonds of the type N(+)Hcdots, three dots, centeredCl(-) with the single chloride anion whilst the [AuCl(4)](-) anion remains discrete. The anti-HIV-1 activity of 1 was determined by a colorimetric direct enzyme reverse transcriptase (RT) assay and a fluorogenic protease (PR) assay. Compound 1 significantly (p<0.05) inhibited RT over a concentration range of 5-250muM and inhibited HIV-1 protease at 100muM. Compound 1 inhibited two very important HIV-1 enzymes (RT and PR) in direct enzyme assays and therefore warrants further evaluation.

In vitro liberation of charged gold atoms: autometallographic tracing of gold ions released by macrophages grown on metallic gold surfaces

The present study demonstrates that cultured macrophages are able to liberate gold ions from metallic gold surfaces, a process suggested to be called "dissolucytosis", in a way analogous to the release taking place when metallic implants are placed in a body. Using the ultra-sensitive autometallographic (AMG) technique, we demonstrate that murine macrophages grown on a surface of metallic gold liberate gold ions. Ultra-structural AMG reveals that the gold ions are located in an ultra-thin membrane-like structure, "the dissolution membrane", intervened between the macrophages and the metal surface. The presence of AMG silver enhanced gold nanoparticles in the dissolution membrane proves that the release of charged gold atoms takes place extracellularly. The dissolution membrane is most likely secreted and chemically controlled by the "dissolucytes", here macrophages, and the membrane is essential for the dissolution of metal implants and particles, which cannot be phagocytosed. Our findings support the notion that whenever a metallic gold surface is attacked by dissolucytes, gold ions are liberated and taken up by surrounding cells. As gold ions can suppress the inflammatory process, it is reasonable to expect that when dissolucytosis takes place in the living organism the liberated gold ions will cause local immunosuppression.

Rheumatic manifestations of human immunodeficiency virus infection

Rheumatic complaints are common in patients with HIV, and HIV positivity confers an increased susceptibility in populations with similar risk factors for HIV infection. With the advent of the modern combined antiretroviral treatment, HAART has had a profound beneficial effect on survival in HIV-infected patients, with lifelong control of HIV infection and normalization of life expectancy; but it has also contributed to both an altered frequency and a different nature of rheumatic complications now being observed in this population, with new rheumatic complications, such as osteoporosis, osteonecrosis, gout, mycobacterial, mycotic osteoarticular infections, and neoplasia perhaps more prevalent. Rheumatologists, internists, and general physicians need to be aware of these changes to provide optimal diagnosis and how to disclose the results to their patients. They also need to be familiar with the management of HIV infection and to direct careful attention to the prevention of HIV transmission in health care facilities.

A single-nucleotide synonymous mutation in the gag gene controlling human immunodeficiency virus type 1 virion production

Viral factors as well as host ones play major roles in the disease progression of human immunodeficiency virus type 1 (HIV-1) infection. We have examined cytotoxic T-lymphocyte activity and HIV-1 DNA PCR results of 312 high-risk seronegative drug users in northern Thailand and identified four seronegative cases positive for both assays. Furthermore, we have identified a synonymous mutation in nucleotide position 75 of the gag p17 gene (A426G) of HIV-1 that belongs to the CRF01_AE virus circulating in Thailand. The replication-competent HIV-1 clone containing the A426G mutation demonstrated a dramatic reduction of virion production and perturbation of viral morphogenesis without affecting viral protein synthesis in cells.

Silver enhancement of quantum dots resulting from (1) metabolism of toxic metals in animals and humans, (2) in vivo, in vitro and immersion created zinc–sulphur/zinc–selenium nanocrystals, (3) metal ions liberated from metal implants and particles

Autometallographic (AMG) silver enhancement is a potent histochemical tool for tracing a variety of metal containing nanocrystals, e.g. pure gold and silver nanoclusters and quantum dots of silver, mercury, bismuth or zinc, with sulphur and/or selenium. These nanocrystals can be created in many different ways, e.g. (1) by manufacturing colloidal gold or silver particles, (2) by treating an organism in vivo with sulphide or selenide ions, (3) as the result of a metabolic decomposition of bismuth-, mercury- or silver-containing macromolecules in cell organelles, or (4) as the end product of histochemical processing of tissue sections. Such nano-sized AMG nanocrystals can then be silver-amplified several times of magnitude by being exposed to an AMG developer, i.e. a normal photographic developer enriched with silver ions. The present monograph attempts to provide a review of the autometallographic silver amplification techniques known today and their use in biology. After achieving a stronghold in histochemistry by Timm's introduction of the "silver-sulphide staining" in 1958, the AMG technique has evolved and expanded into several different areas of research, including immunocytochemistry, tracing of enzymes at LM and EM levels, blot staining, retrograde axonal tracing of zinc-enriched (ZEN) neurons, counterstaining of semithin sections, enhancement of histochemical reaction products, marking of phagocytotic cells, staining of myelin, tracing of gold ions released from gold implants, and visualization of capillaries. General technical comments, protocols for the current AMG methods and a summary of the most significant scientific results obtained by this wide variety of AMG histochemical approaches are included in the present article.

Inhibition of human immunodeficiency virus type 1 replication in latently infected cells by a novel IkappaB kinase inhibitor

In human immunodeficiency virus type 1 (HIV-1) latently infected cells, NF-kappaB plays a major role in the transcriptional induction of HIV-1 replication. Hence, downregulation of NF-kappaB activation has long been sought for effective anti-HIV therapy. Tumor necrosis factor alpha (TNF-alpha) stimulates IkappaB kinase (IKK) complex, a critical regulator in the NF-kappaB signaling pathway. A novel IKK inhibitor, ACHP {2-amino-6-[2-(cyclopropylmethoxy)-6-hydroxyphenyl]-4-piperidin-4-yl-nicotinonitrile}, was developed and evaluated as a potent and specific inhibitor for IKK-alpha and IKK-beta. In this study, we examined the ability of this compound to inhibit HIV-1 replication in OM10.1 cells latently infected with HIV. When these cells were pretreated with ACHP, TNF-alpha-induced HIV-1 replication was dramatically inhibited, as measured by the HIV p24 antigen levels in the culture supernatants. Its 50% effective concentration was approximately 0.56 microM, whereas its 50% cytotoxic concentration was about 15 microM. Western blot analysis revealed inhibition of IkappaBalpha phosphorylation, IkappaBalpha degradation, p65 nuclear translocation, and p65 phosphorylation. ACHP was also found to suppress HIV-1 long terminal repeat (LTR)-driven gene expression through the inhibition of NF-kappaB activation. Furthermore, ACHP inhibited TNF-alpha-induced NF-kappaB (p65) recruitment to the HIV-1 LTR, as assessed by chromatin immunoprecipitation assay. These findings suggest that ACHP acts as a potent suppressor of TNF-alpha-induced HIV replication in latently infected cells and that this inhibition is mediated through suppression of IKK activity.

Gold compounds inhibit adhesion of human cancer cells to vascular endothelial cells

Transcription factor NF-kappaB controls the expression of a number of genes including those for cell adhesion molecules such as E-selectin, ICAM-1 and VCAM-1. These cell adhesion molecules are known to play important roles in a critical step of tumor metastasis; the arrest of tumor cells on the venous or capillary bed of the target organ. NF-kappaB is activated by extracellular signals such as those elicited by the proinflammatory cytokines, TNF and IL-1. Here we demonstrate that IL-1beta induces nuclear translocation of NF-kappaB in human umbilical vein endothelial cells (HUVEC) followed by induction of cell surface expression of E-selectin, ICAM-1 and VCAM-1, and subsequently augments adhesion of cancer cells expressing sialyl Lewis antigen, a ligand of E-selectin. We also demonstrated that the adhesion of tumor cells to IL-1beta-treated HUVEC was inhibited by gold compounds such as aurothioglucose and aurothiomalate. These observations indicate the involvement of NF-kappaB in cancer metastasis and suggest the feasibility of using gold compounds to prevent metastasis.

Calpain is involved in the HIV replication from the latently infected OM10.1 cells

Treatment of OM10.1 cells latently infected with human immunodeficiency virus type 1 (HIV-1) with phorbol ester and calcium ionophore (A23187) induced virus replication which was blocked by N-Ac-Leu-Leu-norleucinal (ALLnL), a calpain inhibitor I, and not by lactacystin, a specific proteasome inhibitor. When the purified NF-kappa B/I kappa B complex was treated with mu-calpain, the specific DNA-binding activity was demonstrated by using electrophoretic mobility shift assay in vitro. This effect of mu-calpain was inhibited by ALLnL and calpastatin and not by lactacystin. In fact, we found that mu-calpain efficiently degraded I kappa B alpha. Furthermore, our Western blotting analysis has revealed that mu-calpain cleaves I kappa B alpha at its N-terminal and C-terminal regions that were previously reported to be involved in the interaction with NF-kappa B p65. These observations indicate that in monocyte/macrophage cells calcium signaling is involved in NF-kappa B activation through activation of calpain and thus calpain inhibitors may be effective in inhibiting the activation of latently infected HIV.

Rheumatic manifestations of human immunodeficiency virus infection

Rheumatic complaints are common in patients with human immunodeficiency virus (HIV) infection. With the advent of the modern combined antiretroviral treatment, life-long control of HIV infection and normalization of life expectancy in HIV-positive patients have become realistic perspectives, but new rheumatic complications, such as osteoporosis, osteonecrosis, gout, and mycobacterial and mycotic osteoarticular infections may be more prevalent. Rheumatologists, internists, and general physicians need to be familiar with the presentation and treatment of these conditions in HIV-positive patients.

RelA-associated inhibitor blocks transcription of human immunodeficiency virus type 1 by inhibiting NF-kappaB and Sp1 actions

RelA-associated inhibitor (RAI) is an inhibitor of nuclear factor kappaB (NF-kappaB) newly identified by yeast two-hybrid screen as an interacting protein of the p65 (RelA) subunit. In this study, we attempted to examine the effect of RAI on transcription and replication of human immunodeficiency virus type 1 (HIV-1). We found that RAI inhibited gene expression from the HIV-1 long terminal repeat (LTR) even at the basal level. Upon in vitro DNA-binding reactions, RAI could directly block the DNA-binding of p65 subunit of NF-kappaB but not that of the p50 subunit or AP1. We found that RAI could also inhibit the DNA-binding of Sp1 and thus inhibit the basal HIV-1 promoter activity. We further examined the effects of RAI on Sp1 and found that RAI colocalizes with Sp1 in the nucleus and interacts with Sp1 in vitro and in vivo. Moreover, we found that RAI efficiently blocked the HIV-1 replication when cotransfected with a full-length HIV-1 clone. These findings indicate that RAI acts as an efficient inhibitor of HIV-1 gene expression in which both NF-kappaB and Sp1 play major roles.

Inhibitory effects of IFN-gamma on HIV-1 replication in latently infected cells

The progress in the use of HAART for the treatment of HIV-infected individuals has been limited by the development of viral resistance and the maintenance of viral latency. New therapeutic strategies geared toward improvement in the host's immune response are now being considered. We found that IFN-gamma induces CIITA through the JAK-STAT pathway and inhibits HIV-1 replication in latently infected cells. Its effect appears to be mediated through the reciprocal action of Tat and CIITA. With this beneficial effect, IFN-gamma and its inducers can be considered as an adjunct to the currently available therapy. We also addressed the safety of using simvastatin, an HMG-CoA reductase inhibitor, to treat dyslipidemia often associated with the use of protease inhibitors. Simvastatin did not show any unfavorable effects on HIV replication, thus could be used safely unless there are any drug interactions when administered.

Therapeutic targeting of human immunodeficiency virus type-1 latency: current clinical realities and future scientific possibilities

Factors affecting HIV-1 latency present formidable obstacles for therapeutic intervention. As these obstacles have become a clinical reality, even with the use of potent anti-retroviral regimens, the need for novel therapeutic strategies specifically targeting HIV-1 latency is evident. However, therapeutic targeting of HIV-1 latency requires an understanding of the mechanisms regulating viral quiescence and activation. These mechanisms have been partially delineated using chronically infected cell models and, clearly, HIV-1 activation from latency involves several key viral and cellular components. Among these distinctive therapeutic targets, cellular factors involved in HIV-1 transcription especially warrant further consideration for rational drug design. Exploring the scientific possibilities of new therapies targeting HIV-1 latency may hold new promise of eventual HIV-1 eradication.

Ethanol enhances TNF-alpha-inducible NFkappaB activation and HIV-1-LTR transcription in CD4+ Jurkat T lymphocytes

During the latent phase of human immunodeficiency virus type 1 (HIV-1) infection, CD4+ T cells carrying replication-competent proviral HIV-1 DNA play an important role in persistence of the virus. Several cofactors can induce and or amplify HIV-1 replication and negatively affect disease progression and pathogenesis. Ethanol consumption is an important risk factor for HIV-1 infection, and it has been implicated in increased HIV-1 replication and progression of infection. Because tumor necrosis factor-alpha (TNF-alpha) is an important modulator of HIV-1 replication, in the present study we examined the possible effects of ethanol on TNF-alpha-inducible signaling associated with HIV-1 replication in human CD4+ T cells (Jurkat E6-1). We demonstrate that clinically relevant ethanol concentrations significantly potentiate TNF-alpha-inducible NFkappaB. Although ethanol effectively collaborated with TNF-alpha, by itself it did not have a direct effect on NFkappaB activation. The ethanol-dependent potentiation of TNF-alpha-inducible NFkappaB nuclear translocation was observed to involve the enhanced degradation of IkappaBalpha. Additionally, the ethanol-mediated potentiation of TNF-alpha-inducible NFkappaB activation was abrogated by the known antioxidant pyrrolidinedithiocarbamate, suggesting an important mechanistic role for reactive oxygen species in this process. In correspondence with its effect on NFkappaB, ethanol was also observed to significantly enhance HIV-1 long terminal repeat-dependent transcription induced by TNF-alpha. Overall, the data provide a molecular basis for the possible role of ethanol as a cofactor that can adversely affect HIV-1 infection and pathogenesis.

Evidence that de novo protein synthesis is dispensable for anti-apoptotic effects of NF-kappaB

The transcription factor NF-kappaB is a positive transcription factor for a number of genes and has been recognized as an anti-apoptotic regulator. However, the mechanism by which NF-kappaB blocks apoptosis is still controversial. Here, we demonstrate the evidence that NF-kappaB could attenuate the TNF-alpha-induced apoptosis without de novo protein synthesis using human pancreatic cancer cell lines, MIA PaCa-2 and Capan-2. The TNF-alpha-induced apoptosis was blocked by IL-1beta, a potent inducer of NF-kappaB activation. This inhibitory effect of IL-1beta was evident when cells were treated with protein synthesis inhibitors such as cycloheximide (CHX). Moreover, NF-kappaB decoy oligonucleotides could not block the anti-apoptotic effect of IL-1beta at doses sufficient to block the NF-kappaB-dependent transcription induced by IL-1beta. To confirm the role of NF-kappaB in blocking apoptosis, we generated stable cell lines expressing IkappaBdeltaN, a highly stable form of IkappaBalpha, a cytoplasmic inhibitor of NF-kappaB. In these stable transfectants, the antiapoptotic effect of IL-1beta was totally abolished, indicating that the anti-apoptotic action of IL-1beta could be ascribed to the NF-kappaB action. These findings show that de novo protein synthesis is dispensable for anti-apoptotic effects of NF-kappaB and support the possibility that NF-kappaB could exert its anti-apoptotic action through protein-protein interaction.

Inhibition of IL-6 and IL-8 induction from cultured rheumatoid synovial fibroblasts by treatment with aurothioglucose

Gold compounds have long been used in the treatment of rheumatoid arthritis (RA). However, their actions in RA have not been clarified. In this study, we examined the effect of one of the monovalent gold compounds, aurothioglucose (AuTG), on the IL-1-induced production of IL-6, IL-8 and granulocyte macrophage colony stimulating factor (GM-CSF) from rheumatoid synovial fibroblasts (RSF) isolated from three RA patients. IL-6 and IL-8 induction but not GM-CSF induction was inhibited in most of the RSF after pretreatment with AuTG. Since gene expression of these cytokines is known to be under the control of a common transcription factor, NF-kappaB, the effect of AuTG on the cellular localization of NF-kappaB (p65 subunit) and on NF-kappaB-DNA binding was examined. Although AuTG treatment did not prevent NF-kappaB nuclear translocation, AuTG blocked the DNA-binding activity of NF-kappaB when examined in vitro. Morphologically, both metal-specific cell staining using p-dimethylaminobenzylidene rhodamine and transmission electron microscopic examinations demonstrated the accumulation of metal gold in the cytoplama and some organella (mitochondria and lysosomes) of the AuTG-treated RSF. These results indicate that one of the anti-rheumatic actions of AuTG might be through its inhibitory action on NF-kappaB.