Resveratrol and ω-3 PUFAs Promote Human Macrophage Differentiation and Function

Monocytes differentiate into M1 and M2 macrophages, which are classically activated by microbial products such as LPS or IFN-γ and interleukins (e.g., the anti-inflammatory and T_h2 promoting IL-4), respectively. The contribution of nutrients or nutrient-based substances such as ω-3 polyunsaturated fatty acids (ω-3 PUFAs) and resveratrol (Res) on the differentiation and function of M1 and M2 macrophages was evaluated. THP-1 cells and peripheral blood mononuclear cells (PBMCs) were differentiated into M1 and M2 cells and activated with LPS/IFN-γ or IL-4/IL-13. Macrophage lineage specific surface determinants (e.g., CD11b, CD11c, CD14, CD206, CD209, CD274, HLA-DR, CCR7, CCR2) were analysed by cytofluorometry. Res and ω-3 PUFAs altered CD14, CD206, CD274 and HL-DR surface expression patterns in M1 and M2 macrophages differentiated from PBMC. LPS/IFN-γ or IL-14/IL-13 activated macrophages subpopulations, which secreted cytokines and chemokines as measured by multiplex ELISA. Res and ω-3 PUFA reduced IL-1β, IL-6, TNF-α, CXCL10/IP-10, CCL13/MCP-4 and CCL20/MIP-3α in LPS/IFN-γ activated human leukaemia THP-1 cells, which is indicative of a dampening effect on M1 macrophages. However, Res increased M1 prototypic cytokines such as IL-1β or IL-6 in macrophages derived from PBMCs and also modified the expression of IL-12p70. Collectively, Res and ω-3 PUFAs distinctly promoted the differentiation and function of M1 and M2 macrophages. We conclude that these substances strengthen the macrophage-mediated effects on the innate and adaptive immune response.

The natural compound ascorbigen modulates NADPH-quinone oxidoreductase (NQO1) mRNA and enzyme activity levels in cultured liver cells and in laboratory rats

Ascorbigen (ABG) is a natural compound that represents a breakdown product of the glucosinolates that are present in Brassica vegetables. It is postulated that ABG may have anticarcinogenic activity; however, the underlying molecular and cellular mechanisms are largely unknown. In the present study we investigated the effect of ABG on the mRNA and enzyme activity levels of NADPH-quinone oxidoreductase (NQO1), which is centrally involved in the detoxification of xenobiotics, in cultured liver cells and in rats. The mRNA levels of NQO1 showed an increase of up to 100% in cultured liver cells (HepG2) following incubation with different concentrations of ABG (3-100 micromol/l) compared to control cells. Furthermore, NQO1 activity was elevated (up to 20%) by ABG treatment. The in vitro results were confirmed in rats who received either 5 mg/day ABG or vehicle for 7 days. Significantly higher mRNA (a 90% increase) and enzyme activity levels (a 40% increase) of NQO1 were detected in the liver of ABG-treated rats as compared to control animals. Current data indicate that ABG is a moderate inducer of the phase II enzyme NQO1, both in cultured hepatocytes and in vivo.

Sulfonylureas and glinides exhibit peroxisome proliferator-activated receptor gamma activity: a combined virtual screening and biological assay approach

Most drugs currently employed in the treatment of type 2 diabetes either target the sulfonylurea receptor stimulating insulin release (sulfonylureas, glinides), or target the peroxisome proliferator-activated receptor (PPARgamma) improving insulin resistance (thiazolidinediones). Our work shows that sulfonylureas and glinides additionally bind to PPARgamma and exhibit PPARgamma agonistic activity. This activity was predicted in silico by virtual screening and confirmed in vitro in a binding assay, a transactivation assay, and by measuring the expression of PPARgamma target genes. Among the measured compounds, gliquidone and glipizide (two sulfonylureas), as well as nateglinide (a glinide), exhibit PPARgamma agonistic activity at concentrations comparable with those reached under pharmacological treatment. The most active of these compounds, gliquidone, is shown to be as potent as pioglitazone at inducing PPARgamma target gene expression. This dual mode of action of sulfonylureas and glinides may open new perspectives for the molecular pharmacology of antidiabetic drugs, because it provides evidence that drugs can be designed that target both the sulfonylurea receptor and PPARgamma. Targeting both receptors could increase pancreatic insulin secretion and improve insulin resistance. Glinides, sulfonylureas, and other acidified sulfonamides may be promising leads in the development of new PPARgamma agonists. In addition, we provide a unified concept of the PPARgamma binding ability of seemingly disparate compound classes.

Methods and biomarkers for the diagnosis and prognosis of cancer and other diseases: towards personalized medicine

The rapid development of new diagnostic procedures, the mapping of the human genome, progress in mapping genetic polymorphisms, and recent advances in nucleic acid- and protein chip technologies are driving the development of personalized therapies. This breakthrough in medicine is expected to be achieved largely due to the implementation of "lab-on-the-chip" technology capable of performing hundreds, even thousands of biochemical, cellular and genetic tests on a single sample of blood or other body fluid. Focusing on a few disease-specific examples, this review discusses selected technologies and their combinations likely to be incorporated in the "lab-on-the-chip" and to provide rapid and versatile information about specific diseases entities. Focusing on breast cancer and after an overview of single-nucleotide polymorphism (SNP)-screening methodologies, we discuss the diagnostic and prognostic importance of SNPs. Next, using Duchenne muscular dystrophy (DMD) as an example, we provide a brief overview of powerful and innovative integration of traditional immuno-histochemistry techniques with advanced biophysical methods such as NMR-spectroscopy or Fourier-transformed infrared (FT-IR) spectroscopy. A brief overview of the challenges and opportunities provided by protein and aptamer microarrays follows. We conclude by highlighting novel and promising biochemical markers for the development of personalized treatment of cancer and other diseases: serum cytochrome c, cytokeratin-18 and -19 and their proteolytic fragments for the detection and quantitation of malignant tumor mass, tumor cell turn-over, inflammatory processes during hepatitis and Epstein-Barr virus (EBV)-induced hemophagocytic lymphohistiocytosis and apoptotic/necrotic cancer cell death.

[Apoptosis: no healthy multi-cellular organisms without regulated cell suicide]

In einem gesunden vielzelligen Organismus aktivieren gefährliche oder nicht mehr benötigte Zellen ein endogenes Selbstmordprogramm. Der daraus resultierende programmierte Zelltod oder Apoptose unterscheidet sich von der pathophysiologischen Form des Zelltodes, der Nekrose, vor allem in der Erhaltung der Zellmembranen. Phagozytierende Zellen beseitigen die Zellreste, sodass bei Apoptose keine Entzündungen auftreten. Störungen der Apoptose sind an der Ursache von vielen Krankheiten beteiligt, wie z.B. Krebs, neurodegenerative Erkrankungen, Autoimmunerkrankungen und Entzündungen. Proteine, die in Apoptose-Prozessen involviert sind, dienen daher als viel versprechende Angriffspunkte für Medikamente. Für einen raschen Erfolg muss das akkumulierte Wissen über die komplizierten Regelkreise der Apoptose in geeigneten «Wissens-Management-Systemen» gesammelt und evaluiert werden.

A streptavidin-biotin-based microarray platform for immunoassays

The authors describe a microarray system for disease diagnosis based on antibody-antigen interactions. Either biotinylated antibodies or antigens are coupled via streptavidin linkers onto a gold surface. This platform has been used to establish recombinant antibody-antigen interactions and to detect specific IgM antibodies in sera of patients suspected of Lyme borreliosis. Therefore, this microarray system can be adapted for further applications.

Advances in recombinant antibody microarrays

Antibody microarrays, one emerging class of proteomic technologies, have broad applications in proteome analysis, disease diagnostics and quantitative analysis. Compared to DNA microarrays, protein targets have significantly more complex interactions with their ligands such as antibodies. To introduce antibody microarrays for clinical diagnostics and thus to complement or replace conventional immunoassays, several new developments are addressed. We discuss different microarray surfaces, immobilization techniques, detection systems and advantages and disadvantages of antibody microarrays compared to standard clinical techniques. Currently, the probes with highest specificity, well-characterized binding properties, and the possibility of large-scale production using display libraries are recombinant antibodies.

ADRIS – The Adverse Drug Reactions Information Scheme

Under the Adverse Drug Reactions Information Scheme (ADRIS) data and knowledge relevant to the etiology of adverse drug reactions (ADRs) such as chemical structure of parent compounds, metabolites, covalent adducts, nucleic acid and protein sequences, protein structures, pharmaco-, toxico- and enzyme kinetics, pharmaco- and toxicodynamics, protein interactions, molecular pathways and complexes, as well as toxicological and clinical outcomes, are collected and logically and semantically related. ADRIS reflects the ontological prerequisite for the creation of databases and knowledge discovery systems for the abstraction and visualization of theragenomic concepts. A final outcome is the prediction of ADRs based on a profound knowledge of drug function and the molecular basics for personalized drug safety and eventually, personalized medicine. 2004

ADRIS ??? The Adverse Drug Reactions Information Scheme

Under the Adverse Drug Reactions Information Scheme (ADRIS) data and knowledge relevant to the etiology of adverse drug reactions (ADRs) such as chemical structure of parent compounds, metabolites, covalent adducts, nucleic acid and protein sequences, protein structures, pharmaco-, toxico- and enzyme kinetics, pharmaco- and toxicodynamics, protein interactions, molecular pathways and complexes, as well as toxicological and clinical outcomes, are collected and logically and semantically related. ADRIS reflects the ontological prerequisite for the creation of databases and knowledge discovery systems for the abstraction and visualization of theragenomic concepts. A final outcome is the prediction of ADRs based on a profound knowledge of drug function and the molecular basics for personalized drug safety and eventually, personalized medicine.

Measurement of the number of molecules of a single mRNA species in a complex mRNA preparation

The normalization of data obtained from hybridization experiments with DNA chips to determine mRNA expression and concentration (gene expression profiling) is an unsolved problem. Furthermore, slight changes in mRNA expression or small numbers of mRNA molecules which may be relevant to disease cannot be detected so far. We have designed a method to calculate the number of molecules of a single mRNA species in a complex mRNA preparation. The basic concept is the transformation of a quantitative problem into a qualitative problem. Individual molecules pertaining to the same molecular species (IMPSMS) are transformed to a mixture of new different molecular species (DMS) and amplified. We propose two implementations of the method. The first procedure is based on a method for cloning tagged nucleic acid molecules onto the surface of micro-beads. It should be possible to transform and determine up to 10(6) IMPSMS into new DMS. The second strategy uses multimeric linkers, a method frequently used in DNA computing to assemble random DNA. The second strategy should be easier to implement but is limited to a few hundred IMPSMS.

Differential calcium response in HeLa and HeLa-Fas cells by cytotoxic T lymphocytes

We constructed a CD95 overexpressing HeLa cell line which was extremely sensitive towards CD95 mediated apoptosis. In these CD95 overexpressing cells, CD95 blocks the nuclear calcium signal induced by perforin positive and CD95 ligand positive killer cells. This phenomenon is highly relevant in states of inflammatory syndromes such as systemic inflammatory response syndrome (SIRS) and sepsis which are associated with a high probability to reactivate latent viruses due to a functional deficiency of cytotoxic effectors.

Anticancer drugs of tomorrow: apoptotic pathways as targets for drug design

Apoptosis or programmed cell death is a set of ordered events that enables the selective removal of cells from tissue and is essential for homeostasis and proper function of multicellular organisms. Components of this signaling network, which include ligands, such as CD95, tumor necrosis factor (TNF) and TNF-related apoptosis-inducing ligand, as well as downstream molecules, such as caspases, Bcl-2 family members, and inhibitor-of-apoptosis proteins, which trigger and regulate apoptosis, are crucial targets for conventional drug development and gene therapy of cancer and other diseases. Here, we focus on apoptotic pathways and propose new potential molecular targets that could prove effective in controlling cell death in the clinical setting.

Microarray of recombinant antibodies using a streptavidin sensor surface self-assembled onto a gold layer

We have developed a sensitive method for the detection of recombinant antibody-antigen interactions in a microarray format. The biochip sensor platform used in this study is based on an oriented streptavidin monolayer that provides a biological interface with well-defined surface architecture that dramatically reduces nonspecific binding interactions. All the antibody or antigen probes were biotinylated and coupled onto streptavidin-coated biochip surfaces (1 microL total volume). The detection limits for the immobilized probes on the microarray surface were 0.5 microgram/mL (200 fmol/spot) for the peptide antigen and 0.1 microgram/mL (3 fmol/spot) for the recombinant antibodies. Optimal concentrations for the detection of the Cy5-labeled protein target were in the range of 20 micrograms/mL. Protein microchips were used to measure antibody-antigen kinetics, to find optimal temperature conditions, and to establish the shelf life of recombinant antibodies immobilized on the streptavidin surface. For recombinant antibody fragments with a kDa of 10-100 nM, we have established an easy and direct immunoassay. In addition, we developed an indirect method for antibody detection with no need for expensive and time-consuming antibody purifications and modifications. Such a method was shown to be useful for large-scale screening of recombinant antibody fragments directly after their functional expression in bacteria. Our data demonstrate that recombinant antibody fragments are suitable components in the construction of antibody chips.

Caspases--their role in apoptosis and other physiological processes as revealed by knock-out studies

Caspases are crucial mediators of apoptosis, a form of physiological cell death. Their activation is carefully controlled by a philogenetically conserved death program, which is indispensable for the homeostasis and development of higher organisms. Dysregulation of apoptosis contributes to the pathogenesis of many human diseases. As effectors of the apoptotic machinery, caspases are considered potential therapeutic targets. In vitro studies have demonstrated the requirement of caspase activity for both the triggering phase as well as the execution of apoptosis, thus providing a molecular base for the fine-tuning of this process by pharmacological agents. The precise roles of the individual caspases in vivo and their functional relation to each other have been best demonstrated in genetically modified animals. The generation of single caspase-deficient mice have confirmed most of the data obtained in vitro and exposed some new aspects previously undetected in the cell culture system. Interestingly, inactivation of many caspases revealed not only their expected participation in apoptotic events as well as in the maturation of cytokines, but also provided hints about the role of at least some caspases in cell differentiation and stimulatory responses. In this review we will discuss what these studies have unveiled about the role of individual caspases in development, apoptosis, and inflammation, with particular focus on their role beyond the apoptotic process.

HIPK2 associates with RanBPM

Using the yeast two-hybrid system, we have identified the Ran-binding protein (RanBPM) as an interaction partner of homeodomain-interacting protein kinase 2 (HIPK2). RanBPM has been described as a centrosomal protein through which Ran regulates the centrosomal function. HIPK2 is mainly a nuclear protein, which among other functions represses transcription mediated by homeodomain containing transcription factors. Here, we show that overexpressed wildtype HIPK2 and a kinase defective mutant of HIPK2 directly interact with RanBPM in the nucleus of mammalian cells. Overexpressed wildtype RanBPM and a kinase defective mutant of HIPK2 co-localise with HIPK2 in defined nuclear structures. A carboxy- and an amino-terminal deletion of HIPK2 do not seem to be able to bind to RanBPM.

HIPK2 overexpression leads to stabilization of p53 protein and increased p53 transcriptional activity by decreasing Mdm2 protein levels

BACKGROUND

HIPK2 (homeodomain-interacting protein kinase 2) has been identified as a nuclear serine/threonine kinase. A central function of HIPK2 is repressing transcription of homeodomain containing transcription factors.

RESULTS AND CONCLUSIONS

We show here that HIPK2 activates transcription mediated by tumor suppressor p53 responsive promoter elements. Overexpression of HIPK2 leads to an increase of p53 protein expression or stability, which becomes enhanced further in the presence of the DNA damaging drug doxorubicin. The effects of HIPK2 on p53 are not observed with kinase deficient HIPK2 mutants. However, HIPK2 is not sufficient for phosphorylation of three crucial serine residues of p53, suggesting that HIPK2-induced p53 activation does not involve phosphorylation of p53. Instead, HIPK2 leads to a downregulation of p53-induced Mdm2 protein and this may lead to stabilization of p53. Overexpression of HIPK2 does not lead to a change of Mdm2 mRNA expression. The data suggest that HIPK2 plays a critical role in p53 mediated cellular responses by removing the p53 inhibitor protein Mdm2 via modification of the protein itself or its intracellular movement.

Strategies for the development of a peptide computer

MOTIVATION

We devise a computational model using protein-protein interactions.

RESULTS

Peptide-antibody interactions can be used to perform a large number of small logical operations in parallel. We show for example how a sequence of operations can be used to compare the number of occurrences of an element in two sets and how to estimate the number of occurrences of an element in a set. Similar to DNA-computing, these techniques could in principle be extended to solve instances of NP-complete problems. We give as an example a procedure to solve examples of the satisfiability problem.

Isolation and characterization of cDNAs for the protein kinase HIPK2

HIPK2 (homeodomain-interacting protein kinase 2) is a CD95 binding partner in yeast. Its primary amino acid sequence is highly conserved between human and mouse. The highest HIPK2 mRNA expression is found in neuronal tissue. The HIPK2 gene is located on human chromosome 7q33-35 and the protein is mainly localized in the nucleus. HIPK2 has been described to play a role as a co-repressor for homeodomain transcription factors.

The serine/threonine kinase HIPK2 interacts with TRADD, but not with CD95 or TNF-R1 in 293T cells

HIPK2 has been described as a homoedomain-interacting protein kinase with a nuclear localization. Here we describe that HIPK2 can also associate with TRADD, a protein that interacts with tumor necrosis factor receptor type 1 (TNF-R1). Under the conditions where HIPK2/TRADD association was found, no direct interaction of HIPK2 with CD95, TNF-R1, FADD or caspase-8 could be detected. Therefore, HIPK2 may play a role in TNF-R1 mediated signaling.

A clinical evaluation of a locking orthodontic facebow

Standard orthodontic facebows may accidentally detach from the appliance buccal tubes at night; this could reduce the effectiveness of extra oral traction and occasionally cause an injury. To try and prevent facebow detachment at night a facebow with a locking mechanism was introduced. This study assessed the ability of 706 consecutively treated patients to learn to wear and use this facebow. The facebows were fitted in 9 different practices supervised by 12 orthodontists. Data from the patients and orthodontists were collected over a 2-year period and covered approximately 166,550 nights. All the orthodontists were able to fit and adjust the facebow; a total of 697 patients successfully used the facebow. Accidental detachment of the facebow at night was reported to be less than 1%. This indicates a significant improvement in the safety of the facebow and should help to improve compliance by increasing the number of hours of wear achieved by the patients.

Rhodamine 110-linked amino acids and peptides as substrates to measure caspase activity upon apoptosis induction in intact cells

Caspases (cysteine aspartate-specific proteases) are a structurally related group of cysteine proteases that cleave peptide bonds following specific recognition sequences. They play a central role in activating apoptosis of vertebrate cells. To measure apoptosis induced by various stimuli and at an early apoptotic stage, caspases are an ideal target. This is especially the case when apoptotic cells have to be analyzed ex vivo before phagocytes remove them. A new and sensitive caspase assay is based on a substrate that contains only aspartate residues linked to rhodamine 110. With this and similar substrates, we are able to detect intracellular caspase activation by flow cytometry after apoptosis induction in intact hematopoetic cell lines.

Hepatic failure and liver cell damage in acute Wilson's disease involve CD95 (APO-1/Fas) mediated apoptosis

Wilson's disease can result in fulminant liver failure due to hepatic copper overload. The CD95 system mediates apoptosis and has been demonstrated to be involved in liver disease. In this study CD95 mediated apoptosis was investigated in patients with fulminant hepatic failure in the course of Wilson's disease and in an in vitro model of copper treated human hepatoma cells. In patients, hepatic expression of CD95 and CD95L mRNA and apoptosis were detected. Copper overload in vitro resulted in hepatocytic apoptosis which could be reduced with a neutralizing anti-CD95L antibody. Copper treatment of hepatocytes results in activation of the CD95 system and induction of apoptosis which is operative during the course of hepatic failure in acute Wilson's disease.

Fas-mediated apoptosis in tumor formation and defense

Survival of cells that usually die by apoptosis contributes to tumor formation. Fas ligand is a specific death factor that induces apoptosis by binding to its receptor Fas. Expression of Fas ligand in tumor cells resistant to Fas-mediated apoptosis helps the tumor to escape surveillance by the immune system. It induces killing of Fas expressing tissue cells as well as killing of lymphocytes that attack and remove tumor cells. Inducing apoptosis in the attacking lymphocytes resembles the mechanism of how Fas ligand contributes to the maintenance of immune privilege. Some cytostatic drugs used in chemotherapy kill their target cells by upregulating expression of Fas and inducing Fas ligand expression in the same cell by different mechanisms. The cells then undergo suicide or fratricide. Tumor cells which became resistant to Fas-mediated apoptosis should be insensitive to cytotoxic drugs that kill drug-sensitive cells by inducing the Fas system. Therefore, depending on the cell type, the Fas system plays complex roles in the origin, survival and killing of tumors.

Reactive oxygen intermediates are involved in the induction of CD95 ligand mRNA expression by cytostatic drugs in hepatoma cells

Oxidative stress has been associated with the induction of programmed cell death. The CD95 ligand/receptor system is a specific mediator of apoptosis. We have used the model of drug-induced apoptosis to assess whether the CD95 ligand mRNA is induced by reactive oxygen intermediates. Treatment of HepG2 hepatoma cells with bleomycin induced the production of reactive oxygen intermediates and, as an additional parameter of oxidative stress, resulted in glutathione (GSH) depletion. In parallel, CD95 ligand mRNA expression was induced. In a similar fashion CD95 ligand mRNA expression increased after treatment with H2O2. Additional treatment with the antioxidant and GSH precursor N-acetylcysteine resulted in partial restoration of intracellular GSH levels and in reduced induction of CD95 ligand mRNA. Induction of CD95 ligand mRNA by bleomycin was further reduced by combined treatment with N-acetylcysteine and deferoxamine. These data suggest a direct role of oxygen radicals in the induction of the CD95 ligand.

Drug-induced apoptosis in hepatoma cells is mediated by the CD95 (APO-1/Fas) receptor/ligand system and involves activation of wild-type p53

Chemotherapeutic drugs are cytotoxic by induction of apoptosis in drug-sensitive cells. We investigated the mechanism of bleomycin-induced cytotoxicity in hepatoma cells. At concentrations present in the sera of patients during therapy, bleomycin induced transient accumulation of nuclear wild-type (wt) p53 and upregulated expression of cell surface CD95 (APO-1/Fas) receptor in hepatoma cells carrying wt p53 (HepG2). Bleomycin did not increase CD95 in hepatoma cells with mutated p53 (Huh7) or in hepatoma cells which were p53-/- (Hep3B). In addition, sensitivity towards CD95-mediated apoptosis was also increased in wt p53 positive HepG2 cells. Microinjection of wt p53 cDNA into HepG2 cells had the same effect. In contrast, bleomycin did not enhance susceptibility towards CD95-mediated apoptosis in Huh7 and in Hep3B cells. Furthermore, bleomycin treatment of HepG2 cells increased CD95 ligand (CD95L) mRNA expression. Most notably, bleomycin-induced apoptosis in HepG2 cells was almost completely inhibited by antibodies which interfere with CD95 receptor/ligand interaction. These data suggest that apoptosis induced by bleomycin is mediated, at least in part, by p53-dependent stimulation of the CD95 receptor/ligand system. The same applies to other anti-cancer drugs such as cisplatin and methotrexate. These data may have major consequences for drug treatment of cancer and the explanation of drug sensitivity and resistance.

Cloning and functional analysis of the hematopoietic cell-specific phospholipase C(gamma)2 promoter

Phospholipase C(gamma)2 (PLCgamma2) is a phospholipid-converting enzyme which, upon receptor stimulation, is activated within membrane-bound signalling complexes. In contrast to the highly ubiquitous PLCgamma1, PLCgamma2 is expressed predominantly in B-lymphocytes. Associated with antigen-coupling receptors it is activated by tyrosine phosphorylation after the triggering of B-cell surface immunoglobulin. We have cloned and sequenced the human PLCgamma2 promoter. Primer extension analysis reveals the existence of a major transcriptional start site. The TATA-less promoter contains G+C-rich stretches with a cluster of contiguous SP1 consensus sites, an NF1, and an AP2 site between bp -220 to -70. A construct containing the region from -189 to +78 confers full promoter activity, as shown by fusion to a luciferase reporter gene construct. The distal part of the promoter between bp -662 to -293 containing an SRE, EBF and CACCC box contributed negatively to promoter activity in the B-cell line Raji but not in three adherent cell lines. In Raji cells, PLCgamma2 mRNA is expressed at low levels with a half life greater than 4 h. After treatment with serum, TPA, retinoic acid, or with 5-azacytidine increased levels of PLCgamma2 mRNA were induced in B-cells.

Lymphocyte apoptosis induced by CD95 (APO-1/Fas) ligand-expressing tumor cells--a mechanism of immune evasion?

The CD95 (APO-1/Fas) system is an important mediator of T-cell cytotoxicity. We investigated this system in 22 hepatocellular carcinomas (HCCs) from patients. All HCCs had partially or completely lost the expression of the CD95 receptor constitutively expressed by normal liver cells and might thus evade CD95-mediated killing. We also considered a new mechanism of immune evasion, namely, the active destruction of T-lymphocytes by tumor cells expressing CD95 ligand (CD95L). CD95L messenger RNA and protein could be detected in the HCCs. In coculture experiments, HepG2 hepatoblastoma cells, expressing CD95L mRNA after treatment with cytostatic drugs, killed CD95+ Jurkat lymphocytes. Our data suggest that tumor cells can evade immune attack by down-regulation of the CD95 receptor and killing of lymphocytes through expression of CD95L.

Persistent membrane translocation of protein kinase C alpha during 12-0-tetradecanoylphorbol-13-acetate-induced apoptosis of LNCaP human prostate cancer cells

Others have reported that the phorbol ester 12-0-tetradecanoylphorbol-13-acetate (TPA), an activator and down-regulator of most protein kinase C (PKC) isozymes, can induce apoptotic cell death of androgen-sensitive LNCaP but not androgen-insensitive PC-3 or DU 145 human prostate cancer cells. As a first step toward uncovering the mechanism by which TPA induces apoptosis of LNCaP cells, we quantified expression of PKC isozyme mRNAs in unmodified and TPA-resistant LNCaP cells and in naturally TPA-resistant PC-3, PC-3M, and DU 145 cells. All of the cell lines and normal prostate expressed RNAs for PKC alpha, delta, epsilon, eta, and mu; only DU 145 cells and normal prostate expressed PKC beta and theta RNAs, and none expressed PKC gamma. The amount of PKC alpha RNA and protein was 6- to 38-fold lower, and PKC mu RNA was 4.5- to 16.5-fold higher in unmodified and TPA-resistant LNCaP cells than in the androgen-independent cells. We examined the effects of TPA on PKC alpha and mu mRNA levels and on membrane translocation of PKC alpha. Incubation with TPA for 6 h or more induced 95% inhibition of cell growth, a transient 12-fold increase and 5-fold decrease in PKC alpha and mu mRNA levels, respectively, and prolonged translocation of PKC alpha to non-nuclear membranes in unmodified LNCaP cells and in TPA-resistant LNCaP cells from which TPA had been removed for 10 days. TPA-resistant LNCaP cells in the continuous presence of TPA, or 24 h after removal of TPA, had down-regulated PKC alpha and remained resistant to re-addition of TPA. These data demonstrate a strong correlation of the presence and absence of membrane PKC alpha with apoptosis and resistance to apoptosis, respectively.

Different apoptotic pathways mediated by Fas and the tumor-necrosis-factor receptor. Cytosolic phospholipase A2 is not involved in Fas-mediated apoptosis

Fas is a cell-surface receptor that belongs to the tumor-necrosis factor (TNF)/nerve growth factor receptor family. Fas can transduce an apoptotic signal through the death domain in the cytoplasmic region, which has similarity with the corresponding region of the TNF type-I receptor. Here, we expressed human Fas in mouse L929 cells or its subline (C12), which express extremely low levels of cytosolic phospholipase A2 (cPLA2). L929 cells were sensitive to the cytotoxic activity of TNF, while C12 cells were resistant. Cross-linking of human Fas with anti-(human Fas antibody) Ig killed both L929 transformants and C12 transformants expressing human Fas. Various inhibitors of the arachidonate metabolism significantly inhibited the TNF-induced cytotoxicity in L929 cells, but they did not have any effect on Fas-mediated apoptosis. These results indicated that cPLA2 is required for TNF-induced apoptosis, whereas it is dispensable for Fas-mediated apoptosis, and suggested that the TNF receptor and Fas use different signaling pathways for apoptosis.

Involvement of an ICE-like protease in Fas-mediated apoptosis

Fas is a type-I membrane protein that transduces an apoptotic signal. Binding of Fas ligand or agonistic anti-Fas antibody to Fas kills the cells by apoptosis. Studies in the nematode Caenorhabditis elegans have suggested that proteases such as interleukin-1 beta-converting enzyme (ICE) or the product of the C. elegans cell-death gene ced-3 are involved in apoptotic signal transduction. The activity of ICE can be inhibited by the product of crmA, a cytokine-response modifier gene encoded by cowpox virus. We report here that expression of crmA inhibits cytotoxicity induced by anti-Fas antibody or tumour necrosis factor (TNF). We have found a specific ICE inhibitor tetrapeptide (acetyl-Tyr-Val-Ala-Asp-chloromethylketone) that also prevents apoptosis induced by anti-Fas antibody. These results suggest an involvement of an ICE-like protease in Fas-mediated apoptosis and TNF-induced cytotoxicity.

Differential expression of protein kinase C isoforms in human colorectal cancers

Protein kinase C (PKC), a serine/threonine kinase central to signal transduction, is implicated in tumor promotion. At present, 10 PKC isoforms have been cloned but their precise tissue-specific role has yet to be defined. In order to determine if PKC is reduced in colorectal cancers (CRC) and if specific PKC isoforms are altered in different stages of human CRC progression, total RNA was extracted from human primary CRC, liver metastases, paired normal mucosa, and liver as well as CRC cell lines and examined for specific PKC isoform mRNA expression. PKC-alpha, beta II, delta, epsilon, eta(L), theta, and zeta were expressed in all tissues examined, while PKC-beta I was not detected. PKC-alpha, beta II, delta, epsilon, and zeta were decreased in most primary CRC. However, the reduction in PKC-beta II was greatest in advanced primary CRC (P < 0.05). Although PKC-gamma was detected in about 29.6% of primary CRC and liver metastases, it was absent from all corresponding normal tissue. In addition, a second band hybridizing to our PKC-gamma probe was uniquely present only in cancerous tissue and not in brain control, suggestive of alternative splicing. PKC-alpha, delta, epsilon, and zeta were present in all cell lines. PKC-beta I/II were both uniformly absent from all cell lines. Since mRNA expression for most PKC isoforms is decreased in CRC, the previously reported decreases in overall PKC activity in CRC are not solely due to a post-translational enzyme modification.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of multiple isoforms of protein kinase C in normal human colon mucosa and colon tumors and decreased levels of protein kinase C beta and eta mRNAs in the tumors

Previous studies have suggested that protein kinase C (PKC) may play an important role in colon carcinogenesis and that human colon tumors have less total PKC enzyme activity than normal tissue. Because PKC is a multigene family that encodes for at least 11 distinct isoforms, in the study reported here we analyzed the expression of six of these isoforms at the mRNA level by northern blot hybridization in 22 pairs of primary colon tumors (of various stages), and adjacent normal mucosa samples. We found that the normal mucosa samples expressed the mRNAs of the following isoforms of PKC, in decreasing order of abundance: PKC delta > PKC eta > PKC alpha > PKC beta > PKC epsilon. There was no consistent difference in the levels of PKC alpha, PKC delta, and PKC epsilon mRNAs between the normal mucosa and the tumor samples. PKC gamma was expressed at a very low level in two of the colon tumors but could not be detected in the remaining tumors or any of the normal mucosa samples. The levels of both PKC beta and PKC eta mRNAs were significantly lower in the tumor samples than in the normal mucosa samples, and this was true of adenomas as well as Dukes' stage A, B, and C adenocarcinomas. Furthermore, the decrease in PKC eta mRNA appeared to be greater in the more poorly differentiated carcinomas. This finding is of interest because PKC eta is normally expressed in the more differentiated cells of epithelial tissues. The decreased levels of both PKC beta and PKC eta mRNAs occurred early in the multistage process of colon carcinogenesis, as it was also seen in adenomas. The functional significance of these changes remains to be determined.

No requirement of reactive oxygen intermediates in Fas-mediated apoptosis

Fas is a cell surface molecule that mediates apoptosis, but the intracellular mechanisms leading to apoptosis are not well understood. It is known that diethylmaleate (DEM)-induced cell death can be blocked by substances with antioxidant activity. Here we have studied whether antioxidants have any effect on Fas-mediated apoptosis and show that they are not able to block Fas-mediated apoptosis. Therefore, it seems that reactive oxygen intermediate (ROI)-dependent and -independent mechanisms which lead to apoptosis do exist. Fas-mediated apoptosis probably proceeds via a ROI-independent pathway.

Activation and substrate specificity of the human protein kinase C alpha and zeta isoenzymes

Protein kinase C (PKC), a class of serine/threonine kinases activated by Ca2+ and/or phospholipids, is involved in a variety of cellular processes such as proliferation, differentiation and secretion. Nine members of the PKC gene family are known; these are differentially expressed in eukaryotic cells and can be divided into two sub-groups: the Ca(2+)-dependent (classical) PKC isoenzymes alpha, beta I, beta II and gamma, and the Ca(2+)-independent neoPKC isoenzymes delta, epsilon, zeta, eta and theta. A detailed biochemical characterisation of these PKC isoenzymes is one prerequisite for the elucidation of their distinct roles within cellular signal transduction. In this study, we report the cloning of a human PKC-zeta cDNA, its expression in recombinant baculovirus-infected insect cells and the partial purification of the PKC-zeta isoenzyme. In comparison to highly purified human PKC alpha, a representative of the classical PKC subgroup, purified PKC zeta was characterised with respect to activator requirement, substrate specificity, proteolytic activation and sensitivity towards PKC inhibitors. In contrast to PKC alpha, PKC zeta exhibits a constitutive kinase activity which is independent of Ca2+, phosphatidylserine and diacylglycerol. Arachidonic acid alone or a combination of gamma-linolenic acid and phosphatidylserine slightly enhance PKC zeta activity. In the presence of the classical PKC activators phosphatidylserine/diacylglycerol, PKC alpha phosphorylates a PKC-alpha pseudosubstrate-derived peptide, an epidermal-growth-factor-receptor-derived peptide, histone III-S and myelin basic protein to an equal extent, whilst PKC zeta phosphorylates only the PKC-alpha-derived peptide. However, arachidonic acid greatly diminishes PKC-alpha activity towards the epidermal-growth-factor-receptor-derived peptide, histone III-S and myelin basic protein, but enhances PKC-zeta activity towards the PKC-alpha-derived peptide. These results indicate a possible modulation of substrate specificity of these two PKC isoenzymes by (the binding of) different activators (to their regulatory domains). In the case of PKC zeta, this finding is strengthened by the fact that the epidermal growth factor receptor-derived peptide, which is not a substrate for the holoenzyme, is significantly phosphorylated by a protein fragment generated by limited proteolysis and comprising only the kinase domain. Furthermore, PKC zeta, in contrast to PKC alpha, is insensitive to PKC inhibitors known to interfere either with the regulatory or the catalytic domain and cannot be activated by phorbol ester treatment of NIH 3T3 cells or insect cells, overexpressing the respective PKC isoenzyme. The potential implications of these findings on the mechanism(s) of activation and the substrate specificity of PKC zeta are discussed.

Selective inhibition of protein kinase C isozymes by the indolocarbazole Gö 6976

Indolocarbazoles have been identified as novel inhibitors of protein kinase C (PKC), with Gö 6976 as one of its most potent and selective representatives. Recombinant PKC isozymes alpha, beta 1, delta, epsilon, and zeta were used in in vitro kinase assays to investigate Gö 6976 with respect to isozyme-specific PKC inhibition. Gö 6850, identical with GF 109203X, another PKC-specific kinase inhibitor, was included in this study as a reference compound. Nanomolar concentrations of the indolocarbazole Gö 6976 inhibited the Ca(2+)-dependent isozymes alpha and beta 1, whereas even micromolar concentration of Gö 6976 had no effect on the kinase activity of the Ca(2+)-independent PKC subtypes delta, epsilon, and zeta. In contrast, the bisindolymaleimide Gö 6850 inhibited all PKC isozymes, however, with a ranked order of potency (alpha > beta 1 > epsilon > delta > zeta). Kinetic analysis revealed that PKC inhibition by Gö 6976 was competitive with respect to ATP, non-competitive with respect to the protein substrate, and mixed type with respect to phosphatidylserine. Further experiments in the presence of different amounts of free Ca2+ indicated that interference with Ca2+ or its binding site is not responsible for the differential inhibition of PKC isozymes by Gö 6976.

Activation of purified human protein kinase C alpha and beta I isoenzymes in vitro by Ca2+, phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate

The increasing number of eukaryotic protein kinase C (PKC) isoenzymes which have been described has raised great interest in potential differences in the cellular expression, the mode of activation and the substrate specificity of these isoenzymes. The last two aspects have mostly been studied with isoenzymes purified from rat or bovine brain or from recombinant-baculovirus-infected insect cells. In this study, we have expressed the human PKC isoenzymes alpha and beta I in recombinant-baculovirus-infected insect cells. The isoenzymes were purified to homogeneity by a four-step procedure which included a reversible Ca(2+)-dependent association/dissociation to and from the endogenous membranes of the lysed insect cells. Characterization of the purified enzymes with respect to ATP requirement and substrate specificity, using the epidermal-growth-factor receptor peptide and histone III-S respectively, revealed no isoenzyme-specific differences. Activation by trypsin or Ca2+ and a variety of different phospholipids and phosphoinositides (in a mixed-micellar assay) gave the following results. Proteolytic cleavage of the PKC isoenzymes by trypsin generated fully activated phospholipid-independent PKC beta I, whereas PKC alpha reached only 50% of the activity obtained in the presence of phospholipids. PKC alpha and beta I showed no difference in their dependence on Ca2+, diacylglycerol (DAG) and phosphatidylserine (PS). Replacement of either DAG or PS by phosphatidylglycerol, cardiolipin, phosphatidylcholine and several phosphoinositides revealed that PtdIns(4,5)P2 can act as a PKC activator similar to DAG, whereas PtdIns can substitute for PS as a cofactor of activation. Thus, at least for the PKC isoenzymes alpha and beta I, a combination of PtdIns and PtdIns(4,5)P2 can fully replace PS and DAG in vitro as the classical activators of PKC.

Protein kinase C isoenzymes: divergence in signal transduction?

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Synthesis and assembly of functionally active human vascular endothelial growth factor homodimers in insect cells

Vascular endothelial growth factor (VEGF) is an angiogenic growth factor with a target-cell specificity highly restricted to vascular endothelial cells. Recombinant baculovirus were constructed for the production of two different forms of the human VEGF protein in insect cells. VEGF165 and VEGF121 proteins produced by Sf158 cells underwent a similar processing compared with mammalian cells, including efficient glycosylation, formation of a disulfide-linked dimer and secretion into the media. Only one of these forms, VEGF165 had a high affinity for heparin and this characteristic was used to purify this form to homogenicity by a two-step heparin-affinity chromatography. The biological activity of the purified 43-kDa homodimer was demonstrated by high-affinity binding to VEGF receptors, and by the induction of DNA synthesis in vascular endothelial cells. A positive angiogenic activity in vivo was demonstrated by the day-13 chorioallantoic-membrane assay. The mitogenic potency of VEGF121 for human umbilical vein endothelial cells was very similar compared to VEGF165. These results demonstrate that an angiogenic growth factor whose normal processing requires glycosylation and disulfide-bridge formation can be efficiently expressed in high concentration (up to 5 micrograms/ml) in insects cells.

Platelet-derived growth factor-induced transcription of the vascular endothelial growth factor gene is mediated by protein kinase C

Platelet-derived growth factor and phorbol ester cause an increase in vascular endothelial growth factor (VEGF) mRNA expression in control NIH 3T3 fibroblasts and NIH 3T3 fibroblasts overexpressing human protein kinase C (PKC) alpha. In the case of phorbol ester-induced VEGF expression, the VEGF mRNA levels were significantly higher in cells overexpressing human PKC alpha as compared to control cells. In cells stimulated with platelet-derived growth factor or phorbol ester, induction of expression was lost after down-regulation of PKC. This indicates that PKC is involved in the signal transduction leading to VEGF expression.

Over-expression of human phospholipase C-gamma 2 enhances platelet-derived growth factor-induced mobilization of intracellular Ca2+ and the release of arachidonic acid and prostaglandins in NIH 3T3 fibroblasts

Over-expression of human phospholipase C-gamma 2 in murine NIH 3T3 fibroblasts has been shown to result in an increased platelet-derived growth factor-mediated formation of inositol phosphates. Here we show that phospholipase C-gamma 2 over-expression is associated with an increased platelet-derived growth factor-mediated release of arachidonic acid, prostaglandin E2, 6-keto prostaglandin F1 alpha and prostaglandin F2 alpha. The phorbol ester, calcium ionophore- and fluoride-induced release of arachidonate and its metabolites is not affected by phospholipase C-gamma 2 over-expression. Over-expression of phospholipase C-gamma 2 is also associated with an enhancement of platelet-derived growth factor-induced change in intracellular Ca2+. These results demonstrate that stimulation of recombinant human phospholipase C-gamma 2 induces a change in the intracellular Ca2+ concentration, a release of arachidonic acid and formation of prostaglandins in NIH 3T3 cells. In control cells platelet-derived growth factor-induced activation of arachidonic acid cascade is rate-limited by the endogenous phospholipase C.

[Lyme borreliosis: significance of the serological diagnosis of an infection with Borrelia burgdorferi in neurological diseases with inflammatory cerebrospinal fluid syndrome]

To look for a correlation between positive antibody-response against Borrelia burgdorferi (Bb) and an inflammatory CSF-syndrome, from May 1988 to May 1989 333 patients from the Neurological Department of the University of Bern underwent lumbar puncture with cell count, quantitative and qualitative protein analysis and antibody determination against Bb in serum and CSF. 6 patients with active syphilis were excluded. The results of the 333 remaining patients were analyzed using chi 2 or Fisher's exact test. The antibody determination was performed using an immunoperoxidase assay (IPA). Our results are calculated for three cut-off points: Bb-IgG 1:64, 1:128, 1:256 and/or Bb-IgM 1:16, 1:32, 1:64. We found 11.7% patients to be seropositive (Bb-IgG 1: greater than or equal to 256 and/or Bb-IgM 1: greater than or equal to 64). We demonstrated the following correlations: elevated cell count (greater than 10/mm3 cells CSF) versus elevated Bb-titer (1: greater than or equal to 256), elevated total protein of CSF (greater than 48 mg%) versus elevated Bb-titer, blood-brain-barrier dysfunction versus elevated Bb-titer. In diagnostic subgroups, the same correlations were only demonstrated for PNS disorders (n = 134), and especially PNS-disorders without compression. 8 cases showed the high risk constellation inflammatory CSF syndrome and highly positive titer (Bb-IgG 1: greater than or equal to 256). Only 2 had typical neuroborreliosis, while in 2 cases the possibility of neuroborreliosis was open. Patients with MS did not show a special risk for Bb-infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Inducible overexpression of human protein kinase C alpha in NIH 3T3 fibroblasts results in growth abnormalities

We have stably overexpressed the human protein kinase C alpha (hPKC alpha) in NIH 3T3 fibroblasts under the control of the interferon (IFN) type I inducible murine Mx promoter. These cells showed a 10-fold increase in the transcription of hPKC alpha mRNA after induction with interferon alpha. The increase in the amount and activity of protein kinase C (PKC)-protein in these cells was only about 3-fold after induction with interferon alpha. Compared to control cells which were transfected with the vector only, the NIH 3T3 fibroblasts transfected with the hPKC alpha cDNA showed already a slightly increased PKC-activity and amount of PKC-protein in the absence of interferon alpha. The hPKC alpha overexpressing cells had an altered, "transformed-like" morphology, which was reversed by staurosporine, an increased growth rate and a higher saturation density. The growth rate was further increased by treating the cells with interferon alpha. The hPKC alpha overexpressing cells were able to grow in soft agarose after treatment with phorbol ester such as TPA (12-O-tetradecanoylphorbol 13-acetate). After phorbol ester and interferon treatment a stronger expression of the protooncogene c-jun was detectable in the hPKC alpha overexpressing cells, whereas expression of c-fos and c-myc was not affected. Since these cells show a specific response pattern due to induced PKC alpha expression they might be useful as an assay system for the development of PKC isozyme-specific inhibitors and activators.

Inducible expression of human phospholipase C-gamma 2 and its activation by platelet-derived growth factor B-chain homodimer and platelet-derived growth factor A-chain homodimer in transfected NIH 3T3 fibroblasts

Growth factors such as platelet-derived growth factor (PDGF) have been shown to activate phospholipase C-gamma 1 (PLC-gamma 1). We have overexpressed the human PLC-gamma 2 (hPLC-gamma 2) cDNA in murine NIH 3T3 fibroblasts using the interferon-type-I inducible murine Mx promoter. Northern blot analysis revealed an induction of hPLC-gamma 2 mRNA by interferon (IFN) alpha of about 25-fold as compared to the uninduced transcript level. Western blot analysis with anti(bovine PLC-gamma 2) antiserum showed increased hPLC-gamma 2 protein levels in hPLC-gamma 2 transfected cells. Induction with IFN alpha resulted only in a slight further increase. After labelling the cells with [35S]methionine an increase of radioactive label in a protein migrating at 148 kDa could be detected in IFN-alpha-stimulated, hPLC-gamma 2 overexpressing cells. PLC activity in homogenates from hPLC-gamma 2 overexpressing cells was increased as compared to control cells transfected with the vector lacking the hPLC-gamma 2 cDNA insert. There was no difference between in vitro PLC activity in homogenates from PDGF B-chain homodimer (BB) treated and untreated cells. PLC activity was mainly present in the soluble fraction. After incubation of hPLC-gamma 2 overexpressing cells with IFN alpha, the in vitro activity of PLC increased significantly in the soluble fraction. Stimulation with PDGF BB increased inositol phosphate production about 3.5-fold in control cells and about 10-fold in hPLC-gamma 2 overexpressing cells. PDGF A-chain homodimer (AA) showed slightly smaller effects. These results demonstrate that human PLC-gamma 2 can be expressed functionally in murine NIH 3T3 fibroblasts and can be activated by both murine PDGF receptors, alpha and beta type.

Biochemical characterization of binding sites for dihydropyridine and omega-conotoxin in brain of adult chicken

Binding studies using the calcium channel blockers omega-conotoxin and dihydropyridine revealed a rather equal amount of binding sites in brain from adult chicken. The omega-conotoxin binding sites could be solubilized using digitonin, without substantial loss, whereas a great decrease in dihydropyridine binding sites was observed, indicating that both types of binding sites have different sensitivity to solubilization. In contrast to ion exchange chromatography where both binding sites comigrated, glycoprotein affinity chromatography led to a different partition of the binding sites in the flow through and eluate fractions. Our results indicate that both types of calcium channel blockers bind to different targets in adult chicken.

High-efficiency expression of rat protein kinase C-gamma in baculovirus-infected insect cells

We have expressed rat protein kinase C-gamma in insect cells using a baculovirus vector. The yield of expressed protein kinase C-gamma is about 4% of total protein. The recombinant protein shows a prominent band at about 80 kDa on SDS-polyacrylamide gels, which can be identified as protein kinase C-gamma by Western blotting using monoclonal antibodies against protein kinase C-gamma. Upon incubation with [gamma-32P]ATP and in the presence of Ca2+, phosphatidylserine and diacylglycerol this protein autophosphorylates. Its enzyme activity shows the characteristic properties of mammalian protein kinase C.