Selective Inhibition of Murine Cytomegalovirus Viral Gene Expression by the Antiviral Peptide TAT-I24

The effect of the antiviral peptide TAT-I24 on viral gene expression in cells infected with murine cytomegalovirus (MCMV) was investigated. The expression of immediate-early, early and late genes was highly induced upon infection with MCMV. In the presence of the peptide, the expression of all tested genes was sustainably reduced to a similar extent, independent of whether they were immediate-early, early or late genes. In contrast, the expression of host genes, such as NF-κB inhibitor alpha (Nfkbia), interferon-induced protein with tetratricopeptide repeats 1 (Ifit1), chemokine (C-X-C motif) ligand 10 (Cxcl10), chemokine (C-C motif) ligand 7 (Ccl7) and chemokine (C-C motif) ligand 5 (Ccl5), which are induced early upon virus infection, was only transiently suppressed in peptide-treated cells. The expression of other host genes which are affected by MCMV infection and play a role in endoplasmic reticulum stress or DNA-damage repair was not inhibited by the peptide. A combination of TAT-I24 with the nucleoside analogue cidofovir showed enhancement of the antiviral effect, demonstrating that viral replication can be more efficiently inhibited with a combination of drugs acting at different stages of the viral life-cycle.

A Novel, Broad-Acting Peptide Inhibitor of Double-Stranded DNA Virus Gene Expression and Replication

Viral infections are a global disease burden with only a limited number of antiviral agents available. Due to newly emerging viral pathogens and increasing occurrence of drug resistance, there is a continuous need for additional therapeutic options, preferably with extended target range. In the present study, we describe a novel antiviral peptide with broad activity against several double-stranded DNA viruses. The 22-mer peptide TAT-I24 potently neutralized viruses such as herpes simplex viruses, adenovirus type 5, cytomegalovirus, vaccinia virus, and simian virus 40 in cell culture models, while being less active against RNA viruses. The peptide TAT-I24 therefore represents a novel and promising drug candidate for use against double-stranded DNA viruses.

Novel avian single-chain fragment variable (scFv) targets dietary gluten and related natural grain prolamins, toxic entities of celiac disease

BACKGROUND

Celiac disease (CD) is a chronic, small intestinal inflammatory disease mediated by dietary gluten and related prolamins. The only current therapeutic option is maintenance of a strict life-long gluten-free diet, which implies substantial burden for CD patients. Different treatment regimes might be feasible, including masking of toxic celiac peptides with blocking antibodies or fragments thereof. The objective of this study was therefore to select and produce a recombinant avian single-chain fragment variable (scFv) directed against peptic-tryptic digested gliadin (PT-Gliadin) and related celiac toxic entities.

RESULTS

Gluten-free raised chicken of same age were immunized with PT-Gliadin. Chicken splenic lymphocytes, selected with antigen-coated magnetic beads, served as RNA source for the generation of cDNA. Chicken VH and VL genes were amplified from the cDNA by PCR to generate full-length scFv constructs consisting of VH and VL fragments joined by a linker sequence. ScFv constructs were ligated in a prokaryotic expression vector, which provides a C-terminal hexahistidine tag. ScFvs from several bacterial clones were expressed in soluble form and crude cell lysates screened for binding to PT-Gliadin by ELISA. We identified an enriched scFv motif, which showed reactivity to PT-Gliadin. One selected scFv candidate was expressed and purified to homogeneity. Polyclonal anti-PT-Gliadin IgY, purified from egg yolk of immunized chicken, served as control. ScFv binds in a dose-dependent manner to PT-Gliadin, comparable to IgY. Furthermore, IgY competitively displaces scFv from PT-Gliadin and natural wheat flour digest, indicating a common epitope of scFv and IgY. ScFv was tested for reactivity to different gastric digested dietary grain flours. ScFv detects common and khorasan wheat comparably with binding affinities in the high nanomolar range, while rye is detected to a lesser extent. Notably, barley and cereals which are part of the gluten-free diet, like corn and rice, are not detected by scFv. Similarly, the pseudo-grain amaranth, used as gluten-free alternative, is not targeted by scFv. This data indicate that scFv specifically recognizes toxic cereal peptides relevant in CD.

CONCLUSION

ScFv can be of benefit for future CD treatment regimes.

Inhibition of Vascular Endothelial Growth Factor Cotranslational Translocation by the Cyclopeptolide CAM741

The cyclopeptolide CAM741 inhibits cotranslational translocation of vascular cell adhesion molecule 1 (VCAM1), which is dependent on its signal peptide. We now describe the identification of the signal peptide of vascular endothelial growth factor (VEGF) as the second target of CAM741. The mechanism by which the compound inhibits translocation of VEGF is very similar or identical to that of VCAM1, although the signal peptides share no obvious sequence similarities. By mutagenesis of the VEGF signal peptide, two important regions, located in the N-terminal and hydrophobic segments, were identified as critical for compound sensitivity. CAM741 alters positioning of the VEGF signal peptide at the translocon, and increasing hydrophobicity in the h-region reduces compound sensitivity and causes a different, possibly more efficient, interaction with the translocon. Although CAM741 is effective against translocation of both VEGF and VCAM1, the derivative NFI028 is able to inhibit only VCAM1, suggesting that chemical derivatization can alter not only potency, but also the specificity of the compounds.

Cotranslocational degradation protects the stressed endoplasmic reticulum from protein overload

The ER's capacity to process proteins is limited, and stress caused by accumulation of unfolded and misfolded proteins (ER stress) contributes to human disease. ER stress elicits the unfolded protein response (UPR), whose components attenuate protein synthesis, increase folding capacity, and enhance misfolded protein degradation. Here, we report that P58(IPK)/DNAJC3, a UPR-responsive gene previously implicated in translational control, encodes a cytosolic cochaperone that associates with the ER protein translocation channel Sec61. P58(IPK) recruits HSP70 chaperones to the cytosolic face of Sec61 and can be crosslinked to proteins entering the ER that are delayed at the translocon. Proteasome-mediated cytosolic degradation of translocating proteins delayed at Sec61 is cochaperone dependent. In P58(IPK-/-) mice, cells with a high secretory burden are markedly compromised in their ability to cope with ER stress. Thus, P58(IPK) is a key mediator of cotranslocational ER protein degradation, and this process likely contributes to ER homeostasis in stressed cells.

The translocation inhibitor CAM741 interferes with vascular cell adhesion molecule 1 signal peptide insertion at the translocon

The cyclopeptolide CAM741 selectively inhibits cotranslational translocation of vascular cell adhesion molecule 1 (VCAM1), a process that is dependent on its signal peptide. In this study we identified the C-terminal (C-) region upstream of the cleavage site of the VCAM1 signal peptide as most critical for inhibition of translocation by CAM741, but full sensitivity to the compound also requires residues of the hydrophobic (h-) region and the first amino acid of the VCAM1 mature domain. The murine VCAM1 signal peptide, which is less susceptible to translocation inhibition by CAM741, can be converted into a fully sensitive signal peptide by two amino acid substitutions identified as critical for compound sensitivity of the human VCAM1 signal peptide. Using cysteine substitutions of non-critical residues in the human VCAM1 signal peptide and chemical cross-linking of targeted short nascent chains we show that, in the presence of CAM741, the N- and C-terminal segments of the VCAM1 signal peptide could be cross-linked to the cytoplasmic tail of Sec61beta, indicating altered positioning of the VCAM1 signal peptide relative to this translocon component. Moreover, translocation of a tag fused N-terminal to the VCAM1 signal peptide is selectively inhibited by CAM741. Our data indicate that the compound inhibits translocation of VCAM1 by interfering with correct insertion of its signal peptide into the translocon.

Selective inhibition of cotranslational translocation of vascular cell adhesion molecule 1

Increased expression of vascular cell adhesion molecule 1 (VCAM1) is associated with a variety of chronic inflammatory conditions, making its expression and function a target for therapeutic intervention. We have recently identified CAM741, a derivative of a fungus-derived cyclopeptolide that acts as a selective inhibitor of VCAM1 synthesis in endothelial cells. Here we show that the compound represses the biosynthesis of VCAM1 in cells by blocking the process of cotranslational translocation, which is dependent on the signal peptide of VCAM1. CAM741 does not inhibit targeting of the VCAM1 nascent chains to the translocon channel but prevents translocation to the luminal side of the endoplasmic reticulum (ER), through a process that involves the translocon component Sec61beta. Consequently, the VCAM1 precursor protein is synthesized towards the cytosolic compartment of the cells, where it is degraded. Our results indicate that the inhibition of cotranslational translocation with low-molecular-mass compounds, using specificity conferred by signal peptides, can modulate the biosynthesis of certain secreted and/or membrane proteins. In addition, they highlight cotranslational translocation at the ER membrane as a potential target for drug discovery.

Negative cross-talk between the human orphan nuclear receptor Nur77/NAK-1/TR3 and nuclear factor-kappaB

The effect of orphan nuclear receptor Nur77 overexpression on activation of an interleukin-2 (IL-2) promoter-luciferase construct was analyzed in the human leukemic cell line Jurkat. Cotransfection of the IL-2 promoter construct together with the Nur77 expression plasmid resulted in a significant repression of IL-2 promoter activation compared to control cells. The repression by Nur77 requires the N-terminal activation function-1 domain. The repressive effect of Nur77 on IL-2 promoter activation is mediated through inhibition of the transcription factor complex nuclear factor-kappaB (NF-kappaB), since blocking or alteration of the IL-2 NF-kappaB binding sites resulted in abrogation of the repressive effect of Nur77. Moreover, further examination of a reporter gene construct containing multiple copies of the IL-2 CD28 response element (CD28RE) showed that Nur77 can inhibit transactivation mediated by the NF-kappaB components p65 and c-Rel. However, no effect of Nur77 was seen on p65-mediated transactivation of a construct containing multiple NF-kappaB binding sites of the HIV LTR. Our data suggest that Nur77 is able to block activation through NF-kappaB when bound to low-affinity NF-kappaB binding sites, such as those located in the IL-2 promoter.

Direct binding of Nur77/NAK-1 to the plasminogen activator inhibitor 1 (PAI-1) promoter regulates TNF alpha -induced PAI-1 expression

Plasminogen activator inhibitor 1 (PAI-1) is the main fibrinolysis inhibitor, and high plasma levels are associated with an increased risk for vascular diseases. Inflammatory cytokines regulate PAI-1 through a hitherto unclear mechanism. Using reporter gene analysis, we could identify a region in the PAI-1 promoter that contributes to basal expression as well as to tumor necrosis factor alpha (TNFalpha) induction of PAI-1 in endothelial cells. Using this region as bait in a genetic screen, we could identify Nur77 (NAK-1, TR3, NR4A1) as an inducible DNA-binding protein that binds specifically to the PAI-1 promoter. Nur77 drives transcription of PAI-1 through direct binding to an NGFI-B responsive element (NBRE), indicating monomeric binding and a ligand-independent mechanism. Nur77, itself, is transcriptionally up-regulated by TNFalpha. High expression levels of Nur77 and its colocalization with PAI-1 in atherosclerotic tissues indicate that the described mechanism for PAI-1 regulation may also be operative in vivo.

Human macrophage inflammatory protein-3alpha/CCL20/LARC/Exodus/SCYA20 is transcriptionally upregulated by tumor necrosis factor-alpha via a non-standard NF-kappaB site

The 5'-flanking sequences of the human macrophage inflammatory protein-3alpha/CCL20 gene were cloned and transfected into G-361 human melanoma cells in a luciferase reporter construct. Tumor necrosis factor-alpha (TNF-alpha) treatment stimulated luciferase expression, and promoter truncations demonstrated that TNF-alpha inducibility is conferred by a region between nt -111 and -77, which contains a non-standard nuclear factor-kappaB (NF-kappaB) binding site. The requirement for NF-kappaB was demonstrated as follows: (i) mutations in this NF-kappaB site abrogated TNF-alpha responsiveness; (ii) TNF-alpha activated a construct containing two copies of the CCL20 NF-kappaB binding site; (iii) overexpression of NF-kappaB p65 activated the CCL20 promoter; (iv) NF-kappaB from nuclear extracts of TNF-alpha-stimulated cells bound specifically to this NF-kappaB site.

Gewichtsentwicklung beim Kaninchen (Oryctolagus cuniculus) nach Transfer reziproker Kernkombinationen in eine neutrale Ammenlinie

Abstract. Title of the paper: Development of body weight in rabbits (Oryctolagus cuniculus) after embryo transfer of reciprocal nuclear combinations to a neutral line of recipients. Ihe article describes differences in the development of body weight ofthe Fl-generations in the rabbit, which oecured after embryo transfer from reciprocal nuclear combinations to a neutral line of reeipients. These differences can be explained as expression of maternal cyto-plasmatical and / or imprinting-effects. The two races – Deutsche Riesen and Farbzwerge –, which are extremly different in body weight were used for the reciprocal crosses. The neutral reeipients were a commercial breed „Zika". Results show a significant higher litter weight of the offspring which descended from the heavier mother race. On the 84th day of life exists no differences in weight between the crosses. Differences were within the crosses between the females and males and between the crosses reciprocal different. Causes for the reciprocal sexdimorphism can be A: extrachromosomal respectively cytoplasmatic factors or B: a sex-linked and a sex-influenced heredity, which coinside and are regulated by imprinting

Natural metabolites of 1alpha,25-dihydroxyvitamin D(3) retain biologic activity mediated through the vitamin D receptor

1alpha,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)), the active metabolite of vitamin D, mediates many of its effects through the intranuclear vitamin D receptor (VDR, NR1I1), that belongs to the large superfamily of nuclear receptors. Vitamin D receptor can directly regulate gene expression by binding to vitamin D response elements (VDREs) located in promoter or enhancer regions of various genes. Although numerous synthetic analogs of 1alpha,25(OH)(2)D(3) have been analysed for VDR binding and transactivation of VDRE-driven gene expression, the biologic activity of many naturally occurring metabolites has not yet been analyzed in detail. We therefore studied the transactivation properties of 1alpha,24R, 25-trihydroxyvitamin D(3) (1alpha,24R,25(OH)(3)D(3)), 1alpha, 25-dihydroxy-3-epi-vitamin D(3) (1alpha,25(OH)(2)-3-epi-D(3)), 1alpha,23S,25-trihydroxyvitamin D(3) (1alpha,23S,25(OH)(3)D(3)), and 1alpha-hydroxy-23-carboxy-24,25,26,27-tetranorvitamin D(3) (1alpha(OH)-24,25,26,27-tetranor-23-COOH-D(3); calcitroic acid) using the human G-361 melanoma cell line. Cells were cotransfected with a VDR expression plasmid and luciferase reporter gene constructs driven by two copies of the VDRE of either the mouse osteopontin promoter or the 1alpha,25(OH)(2)D(3) 24-hydroxylase (CYP24) promoter. Treatment with 1alpha,25(OH)(2)D(3) or the metabolites 1alpha,24R,25(OH)(3)D(3), 1alpha,25(OH)(2)-3-epi-D(3), and 1alpha,23S,25(OH)(3)D(3) resulted in transactivation of both constructs in a time- and dose-dependent manner, and a postitive regulatory effect was observed even for calcitroic acid in the presence of overexpressed VDR. The metabolites that were active in the reporter gene assay also induced expression of CYP24 mRNA in the human keratinocyte cell line HaCaT, although with less potency than the parent hormone. A ligand-binding assay based on nuclear extracts from COS-1 cells overexpressing human VDR demonstrated that the metabolites, although active in the reporter gene assay, were much less effective in displacing [(3)H]-labeled 1alpha,25(OH)(2)D(3) from VDR than the parent hormone. Thus, we report that several natural metabolites of 1alpha,25(OH)(2)D(3) retain significant biologic activity mediated through VDR despite their apparent low affinity for VDR.

Up-regulation of interleukin-1beta-stimulated interleukin-8 in human keratinocytes by nitric oxide

Nitric oxide (NO) is able to regulate the expression of a number of inflammatory mediators. In this study, the effect of NO on the expression of the chemokine interleukin-8 (IL-8) by primary human keratinocytes and the lines KB and HaCaT was examined. Incubation with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) for 24 hr increased IL-8 protein only in HaCaT cells, partly due to the presence of constitutive interleukin-1 (IL-1). However, in combination with IL-1beta, SNAP enhanced both IL-8 mRNA and protein in all three cell types. Transfection of cells with an IL-8 promoter reporter gene construct showed that the effect of NO was at least partly due to transcriptional activation. Despite small variations in the response to NO by the three cell types, these results demonstrate that NO can up-regulate IL-1beta-stimulated IL-8 expression in human keratinocytes. This study provides a regulatory mechanism which may be important in the context of skin inflammation, and supports the role of NO as an inflammatory mediator in the skin.

1Alpha,25-dihydroxyvitamin D3 decreases DNA binding of nuclear factor-kappaB in human fibroblasts

1Alpha,25-dihydroxyvitamin D3 (1,25-(OH)2-D3), the active metabolite of vitamin D, can inhibit NF-kappaB activity in human MRC-5 fibroblasts, targeting DNA binding of NF-kappaB but not translocation of its subunits p50 and p65. The partial inhibition of NF-kappaB DNA binding by 1,25-(OH)2-D3 is dependent on de novo protein synthesis, suggesting that 1,25-(OH)2-D3 may regulate expression of cellular factors which contribute to reduced DNA binding of NF-kappaB. Although NF-kappaB binding is decreased by 1,25-(OH)2-D3 in MRC-5 cells, IL-8 and IL-6 mRNA levels are only moderately downregulated, demonstrating that inhibition of NF-kappaB DNA binding alone is not sufficient for optimal downregulation of these genes.

1alpha,25-dihydroxyvitamin D3 and a variety of its natural metabolites transcriptionally repress nuclear-factor-kappaB-mediated interleukin-8 gene expression

Regulation of interleukin-8 (IL-8) gene transcription occurs mainly through the sequences -94 to -71 of the 5'-flanking region of the IL-8 gene, involving the transcription factors nuclear factor for interleukin-6 (NF-IL-6) and nuclear factor kappaB (NF-kappaB). The human melanoma cell line A3 was derived from G-361 cells by stable transfection with an IL-8 promoter-luciferase construct containing these sequences. 1alpha,25-Dihydroxyvitamin D3 (calcitriol) repressed IL-8 promoter activity induced by tumor necrosis factor-alpha (TNF-alpha) by 50%, compared to 30% inhibition using dexamethasone, an effect consistent with its effect on TNF-alpha-induced IL-8 release and IL-8 mRNA levels. A variety of vitamin D metabolites caused the same repressive effect on IL-8 promoter activation as calcitriol. However, only those metabolites which were able to transactivate a classical vitamin D response element had the ability to repress IL-8 promoter activation, suggesting that this repression is mediated via vitamin D receptor (VDR). Furthermore, overexpression of VDR in the parental G-361 cell line enhanced the repressive effect of calcitriol on activation of the IL-8 promoter by either TNF-alpha stimulation or overexpression of the NF-kappaB subunit p65. Electrophoretic mobility shift assays using nuclear extracts from A3 cells showed that calcitriol decreased the abundance of nuclear factors bound to the NF-kappaB binding site of the IL-8 promoter and this reduced binding of NF-kappaB proteins presumably contributes to its inhibitory action.

Synergistic activation of interleukin-8 gene transcription by all-trans-retinoic acid and tumor necrosis factor-alpha involves the transcription factor NF-kappaB

Induction of interleukin-8 (IL-8) by IL-1 or tumor necrosis factor (TNF), and repression by interferons or glucocorticoids have been shown to involve sequences between nucleotides -94 and -71 of the 5'-flanking region, and the transcription factors NF-IL-6 and NF-kappaB. The A3 cell line was derived from the human melanoma cell line G-361 by stable transfection with part of the IL-8 promoter (nucleotides -101 to +40 from transcription start) fused to the luciferase coding region. These regulatory sequences were sufficient for transcriptional activation by all-trans-retinoic acid (ATRA), 9-cis-retinoic acid, IL-1beta, or TNF-alpha. Simultaneous treatment of A3 cells with ATRA and TNF-alpha resulted in a dose- and time-dependent synergistic increase in luciferase expression and IL-8 mRNA levels. Transient transfections of the parental cell line demonstrated that the NF-kappaB binding site is essential for this synergistic transactivation. Electrophoretic mobility shift assays with nuclear extracts of A3 cells showed that stimulation with ATRA and TNF-alpha for more than 16 h resulted in enhanced NF-kappaB binding compared to that induced by TNF-alpha alone. The simultaneous treatment with ATRA and TNF-alpha also resulted in changes in the composition of NF-kappaB complexes bound to the IL-8 NF-kappaB site, preventing the formation of two TNF-alpha-inducible binding activities. We suggest that these complexes consist of repressive factors which, when removed, allow enhanced binding of NF-kappaB to its cognate site.

Genes related to growth and invasiveness are repressed by sodium butyrate in ovarian carcinoma cells

Down-regulation of oncogene expression is one of the hallmarks of the process whereby transformed cells are forced into differentiation and/or growth arrest by potent inducers and therefore can represent an interim end point in cancer treatment. The differentiation inducer sodium butyrate (NaB) arrested growth of N.1 ovarian carcinoma cells and repressed expression of cyclin D1/prad1 and the invasiveness-related protease plasminogen activator-urokinase (plau). This was accompanied by the acquisition of a differentiated morphology, all of which characteristics were maintained as long as N.1 cells were exposed to the inducer. In accordance with a differentiated phenotype was the finding that fibronectin expression was increased significantly. Recently, it was shown that NaB represses the transcription factor c-myc by blocking Ca2+ signals and modulating serine threonine kinase activity. We wanted to investigate NaB-mediated interference on signals contributing to the expression on prad1, plau and growth arrest-specific 6 (gas6). Protein kinase A (PKA) inactivation de-repressed prad1 and plau transcript levels. NaB had onlygeneral but no specific influence on PKA-modulated prad1 and plau expression however. Protein kinase C activation up-regulated plau transcript levels, but not that of prad1. Prad1 expression seemed to depend on Ca2+-triggered signals. Constitutive plau expression was insensitive to additional Ca2+-mediated signals, but it became responsive upon NaB treatment.

Bidirectional interactions between the estrogen receptor and the cerbB-2 signaling pathways: heregulin inhibits estrogenic effects in breast cancer cells

The responsiveness of estrogen receptor (ER)-positive breast cancer to endocrine therapy is frequently reduced in cells over-expressing c-erbB-2. Stimulation of ER suppresses c-erbB-2, indicating that estrogen controls the activity of c-erbB-2. Heregulin (HRG) has been described to bind to c-erbB-3/c-erbB-4 and to stimulate c-erbB-2. Here we describe the effects of HRG on cell growth and on ER and c-erbB-2 expression in breast cancer cell lines containing distinct levels of c-erbB-2 and ER (BT-474: c-erbB-2 , ER+; MDA-MB-361: c-erbB-2++, ER++; MCF-7: c-erbB-2+, ER ). Proliferation of estrogen-stimulated, c-erbB-2 and ER-positive cells is inhibited by HRG in a dose-dependent manner. In addition, HRG dose-dependently inhibits ER expression. Estrogen, however, inhibits c-erbB-2. Estrogen-mediated down-regulation of c-erbB-2 is most pronounced in MCF-7 but weaker in BT-474. In the latter cells HRG efficiently blocks the estrogenic effect on c-erbB-2. In MCF-7 cells, however, the inhibition of c-erbB-2 cannot be completely reverted by HRG. This modulation occurs in all 3 cell lines at protein, RNA and transcriptional levels, suggesting that the activity of the c-erbB-2 promoter, which contains an estrogen-responsive region, is affected by HRG. The intensity of the mutual inhibition between the HRG/c-erbB-2 and the estrogen/ER system depends on the relative levels of ER and c-erbB-2 expression in the respective cell lines.

Nitric oxide regulates IL-8 expression in melanoma cells at the transcriptional level

We investigated the role of nitric oxide (NO) in the expression of interleukin-8 (IL-8) in the human melanoma cell line, G361. Three NO donors, 3-morpholinosydnonimine hydrochloride (SIN-1), S-nitroso-N-acetylpenicillamine (SNAP), and S-nitroso-L-glutathione (SNOG), all caused an increase in both IL-8 protein secretion and promoter activity. Truncation of the promoter showed that 101 bp of the 5' flanking region proximal to the transcription start site are sufficient for the response to NO. Furthermore, mutation of the NF-kappa B and NF-IL-6 binding sites led to a significant decrease in NO-stimulated promoter activity. The nitric oxide synthase inhibitor, NG-amino-L-homoarginine (NAHA), inhibited TNF-alpha-stimulated IL-8 promoter activity by 60%. Addition of excess L- but not D-arginine partially reversed the NAHA-mediated inhibition. These results demonstrate that NO is an endogenous regulator of IL-8 production in G361 melanoma cells.

Macrophage colony-stimulating factor is expressed by an ovarian carcinoma subline and stimulates the c-myc proto-oncogene

A small, fast-growing and non-differentiated clone (N.1) derived from the heterogeneous human epithelial ovarian carcinoma cell line HOC-7 produces an autocrine/paracrine factor that is secreted into the cell culture supernatant. This factor is capable of enhancing mRNA levels of the proliferation-related oncogene c-myc in the more differentiated clone D3 and in normal human fibroblasts MRC.5, but also in N.1 cells themselves. Supernatants enriched for this paracrine/autocrine factor also confer a mitogenic stimulus as measured by [3H]thymidine incorporation. Trypsin can neutralise the stimulating activity of the secreted factor as well as monoclonal antibodies directed against macrophage colony-stimulating factor (M-CSF). We show that M-CSF and also M-CSF receptor are expressed in N.1 cells and that recombinant M-CSF induces c-myc transcript levels in N.1 cells. This investigation raises the possibility that M-CSF might be an autocrine growth factor in non-differentiated ovarian carcinomas. Inappropriate cytokine production could create a tumour-promoting microenvironment in this cancer type.

Retinoic acid induced death of ovarian carcinoma cells correlates with c-myc stimulation

In the ovarian adenocarcinoma subline N.I, all-trans retinoic acid (ATRA) induced substantial cell death. This response was elicited only at decreased serum levels. Exposure of N.I cells to increasing concentrations of ATRA was accompanied by a considerable up-regulation of c-myc transcript levels that correlated with the rate of cell killing, which itself was an active process as judged by sustained transcriptional expression. ATRA-triggered rounding and detaching of single cells from the substratum was accompanied by degradation of genomic DNA. We show that the N.I model cell line, which is otherwise highly ATRA-resistant, can undergo an ATRA-triggered suicide program when serum is limited. The accompanying c-myc up-regulation seems to be mediated by retinoic-acid-receptor-independent pathways involving membrane-associated phospholipases instead, because manoalide partly suppressed c-myc induction by ATRA but left constitutive c-myc expression unaffected.

Regulation of interleukin-8 gene expression by all-trans retinoic acid

We have studied the relationship between interleukin-8 (IL-8) and interleukin-1 alpha (IL-1 alpha) release after stimulation with all-trans retinoic acid (ATRA) and tumor necrosis factor-alpha (TNF-alpha) in the human epithelial ovarian cancer cell line HOC-7. Both IL-1 alpha and IL-8 protein release were enhanced by treatment with ATRA and TNF-alpha after 48 h exposure. Blocking of IL-1 alpha activity in HOC-7 cells with either IL-1 receptor antagonist (IL-1ra) or a neutralizing antibody directed against IL-1 alpha resulted in a dose-dependent decrease of IL-8 release by ATRA, TNF-alpha and IL-1 alpha treated HOC-7 cells. Expression of IL-8 mRNA was enhanced by the individual stimuli, whereas co-treatment with IL-1ra resulted in a loss of IL-8 specific transcripts, except in TNF-alpha treated cells. Inhibition of de novo protein synthesis by cycloheximide (CHX) and simultaneous blocking of IL-1 alpha activity by IL-1ra for 24 h revealed that ATRA controls IL-8 gene expression transcriptionally and that the extent of IL-8 protein release can be markedly influenced by cellular expressed IL-1 alpha.

Sodium butyrate inhibits c-myc splicing and interferes with signal transduction in ovarian carcinoma cells

Sodium butyrate (NaB), a physiologically produced short chain fatty acid, dramatically changes the growth rate and also the morphology of a fast growing subclone (N.1) derived from the heterogenous human ovarian carcinoma HOC-7. The mRNA of the growth related proto-oncogene c-myc, constitutively expressed in N.1 cells decreased significantly within 24 h of NaB treatment and remained suppressed until the NaB block was released. Down-regulation was accomplished partially by accelerating degradation of c-myc mRNA and by inhibiting splicing of c-myc transcripts. We demonstrated that NaB blocked general mechanisms in signal transduction, such as the release of Ca2+ from intracellular stores, and modulated the activity of serine/threonine kinases. The multiple effects of sodium butyrate on HOC-7 derivatives, as well as on a variety of other cell types investigated by others, may be due to interference with general mechanisms of signal transduction.

Two-dimensional gel electrophoresis for controlling and comparing culture supernatants of mammalian cell culture productions systems

A recombinant Chinese hamster ovary cell line, producing human erythropoietin, was cultivated in a continuous mode in a stirred tank reactor applying different dilution rates. In order to monitor the stability of this expression system, product and non-product proteins of the cell culture supernatant were analyzed by two-dimensional electrophoresis. The consistency of the isoforms of the recombinant product was determined by western blot combined with specific staining. The same cell line was propagated in a high cell density cultivation system based on macro-cell-aggregates. The patterns of secreted proteins of the cell line cultivated in the different systems were compared in order to detect modifications in protein expression of the product and of non product proteins relevant for cell culture supernatant. Hardly any alterations in two-dimensional pattern were detectable. The isoforms of erythropoietin, as well as the overall pattern of secreted proteins, detectable with the two-dimensional electrophoresis method were remarkably stable under different cultivation conditions.

Retinoic acid receptors in retinoid responsive ovarian cancer cell lines detected by polymerase chain reaction following reverse transcription

The growth inhibitory effects of all-trans and 13-cis retinoic acid (RA) and of the synthetic retinoids TTNPB, TTNPB-ethylester and TTNN were studied on seven human epithelial ovarian cancer cell lines and one ovarian teratocarcinoma cell line. Six of seven ovarian adenocarcinoma cell lines were inhibited in their growth by RA and by synthetic retinoids in a dose dependent manner. No response to these substances was observed for the ovarian teratocarcinoma cell line. The knowledge that RA and retinoids exert their action on the cells via nuclear receptors led us to examine the expression of RAR-alpha, -beta and -gamma mRNA by these cell lines by polymerase chain reaction following reverse transcription. All cell lines expressed RAR-alpha and -gamma mRNA and six of the eight cell lines were found to express additionally RAR-beta mRNA, among them the ovarian teratocarcinoma cell line. Our data indicate that there was no direct association between the presence of RAR subtype transcripts and the response to retinoids in ovarian cancer cell lines.

Two-dimensional electrophoresis as a tool for control of quality and consistency in production systems using animal cells

A nonrecombinant human melanoma cell line and recombinant chinese hamster ovary (CHO) cells were used as examples for long-term in vitro cultivation in protein-free media. The method used to monitor the consistency of protein release by these mammalian cells was two-dimensional electrophoresis with immobilized pH gradient. Secreted proteins from a melanoma cell line cultivated in a continuous fermentation system over a period of 22 months were monitored. Two-dimensional patterns of secreted proteins were compared and the stability of their composition was determined over a period of nearly 14 months, with significant pattern variation being observed after 14 months. The protein pattern from this extended in vitro culture was compared to those of the very same melanoma cell line recultivated after being frozen in liquid nitrogen for more than 2 years. Due to the high resolution of complex polypeptide mixtures and the possibility to detect even minor differences in the composition of protein patterns, we propose the two-dimensional electrophoresis as a tool for quality assessment in animal cell culture technology.

Flow cytometry and two-dimensional electrophoresis (2-DE) for system evaluation of long term continuous perfused animal cell cultures in macroporous beads

Immobilization of r-CHO cells at high density using macroporous polyethylene carriers in a modular fluidized bed reactor is demonstrated. Specific growth rates of the cells are measured by incorporation of BrdU. At a cell density of about 10(8) cells/ml a stable growth rate of 0.004 h-1 was established. Total release of proteins into the culture supernatant during protein-free perfusion was analyzed by 2-DE in various phases of the long-term culture showing very similar patterns indicating a constant pattern of gene expression.