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Biomedical subjects

F Herrmann

Publications and source records attributed to F Herrmann.

At least 127 records · Page 7Linked to original sources
PubMed1993

Phorbol ester 12-O-tetradecanoylphorbol-13-acetate down-regulates expression of the c-kit proto-oncogene product.

Modulation of expression of the c-kit proto-oncogene product, the receptor for the recently identified stem cell factor, was studied on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated cultures of CD34+ normal bone marrow progenitor cells, blast cells from patients with primary acute myelogenous leukemia, cells from the leukemia cell lines HEL and MO7E, as well as cultured HMC-1 mast cells. Expression of c-kit was assessed on both RNA and protein level employing standard Northern blotting, reverse transcription, and polymerase chain reaction-based Southern blotting, as well as cell surface labeling with anti-c-kit mAb YB5.B8. Treatment of virtually all cell types with nontoxic concentrations of TPA (10(-9) M) for at least 48 h was associated with down-regulation of synthesis of c-kit transcripts and stem cell factor-receptor surface expression. Studies on the mechanism of action of TPA utilizing the HEL erythroleukemia line showed that TPA was primarily acting by accelerating the turnover of c-kit RNA most likely through induction of a destabilizing protein. The effect of TPA on c-kit expression levels was independent of TPA-mediated induction of differentiation since other compounds including IFN-gamma, vitamin D3, retinoic acid, arabinofuranosylcytosine, butyric acid, and camptothecin, which also effectively induced differentiation of HEL cells, failed to alter levels of c-kit expression.

Base Sequence↗
PubMed1993

Transforming growth factor-beta 1 interferes with the proliferation-inducing activity of stem cell factor in myelogenous leukemia blasts through functional down-regulation of the c-kit proto-oncogene product.

Blast cells, obtained from patients with acute myelogenous leukemia (AML), that express surface binding sites for human stem cell factor (SCF) respond proliferatively upon exposure to this molecule. In the presence of human transforming growth factor-beta 1 (TGF-beta 1) the capacity of SCF to augment the proliferative state of AML blasts was, however, almost completely abolished. This inhibitory action of TGF-beta 1 could be reversed by a neutralizing anti-TGF-beta 1 antibody. Studies on the mechanism of TGF-beta 1 inhibition of SCF-induced proliferation of AML blasts revealed that TGF-beta 1 treatment of these cells was associated with down-regulation of SCF receptor surface expression, as detected with a specific monoclonal antibody, which appeared to be preferentially due to an acceleration of decay of mRNA for the c-kit proto-oncogene encoding the SCF receptor, without an effect on the overall transcriptional activity of the c-kit gene. Direct evidence to prove the importance of c-kit down-regulation in the inhibitory effect of TGF-beta 1 on AML growth came also from experiments demonstrating that signal transduction of SCF could be significantly diminished in the presence of TGF-beta 1, as demonstrated by measuring c-kit kinase-associated phosphorylation of target proteins.

Cell Division↗
PubMed1993

Transcriptional activation of the macrophage colony-stimulating factor gene by IL-2 is associated with secretion of bioactive macrophage colony-stimulating factor protein by monocytes and involves activation of the transcription factor NF-kappa B.

Human peripheral blood monocytes (Mo) constitutively display the beta-chain of the receptor for IL-2, whereas expression of the IL-2R alpha-chain is not constitutive but inducible with IL-2. Here we report that binding of human IL-2 to its binding site leads to transcriptional activation of the macrophage CSF (M-CSF) gene in Mo resulting in accumulation of M-CSF mRNA and subsequent release of bioactive M-CSF protein as demonstrated by ELISA and inhibition of IL-2 induced release of an activity-stimulating growth of monocyte-type colonies by a neutralizing anti-M-CSF antibody. Transcriptional activation of the M-CSF gene by IL-2 is preceded by enhanced binding activity of the transcription factor NF-kappa B to its recognition sequence in the 5' regulatory enhancer region of the M-CSF gene. Moreover, using a heterologous promoter (herpes thymidine kinase) construct containing the NF-kappa B consensus sequence, it is shown that NF-kappa B binding by an IL-2-induced monocyte-derived nuclear protein confers reporter gene (human growth hormone) activity. Taken together, our findings indicate that IL-2 induces gene expression of M-CSF in human blood-derived Mo and provide evidence for involvement of NF-kappa B in transcriptional regulation of this gene.

Animals↗
PubMed1993

Ionizing radiation induces expression of interleukin 6 by human fibroblasts involving activation of nuclear factor-kappa B.

We here report that human lung fibroblasts respond to x-ray treatment (XRT) with release of interleukin (IL)-6. Synthesis of IL-6 upon ionizing radiation is preceded by an increase of IL-6 transcript levels resulting from transcriptional activation of the IL-6 gene. Analysis of deleted fragments of the IL-6 promoter indicated that transcriptional activation of the IL-6 promoter was due to enhanced binding activity of the transcription factor nuclear factor (NF)-kappa B. Although AP-1 did not participate in the rapid induction of the IL-6 promoter, its binding activity was also enhanced by XRT. In contrast to binding kinetics observed with NF-kappa B, AP-1 binding following XRT was biphasic with the second peak being dependent on de novo protein synthesis. In contrast, however, NF-IL-6 activity was not enhanced by XRT in fibroblasts. The introduction of both the NF-kappa B- and the AP-1 recognition sequence conferred inducibility by XRT to a heterologous promoter, with reporter gene activity being maximal 24 or 48 h following XRT, respectively. Sequential activation of two distinct transcription factors might thus contribute to synchronize transcriptional activation of different genes participating in the x-ray response.

Base Sequence↗
PubMed1993

The mitogenic response of T cells to interleukin-2 requires Raf-1.

The product of the c-raf-1 proto-oncogene, Raf-1, is known to encode a 74-kDa ubiquitously expressed cytoplasmic serine/threonine kinase. Various growth factors such as epidermal growth factor, acidic fibroblast growth factor, platelet-derived growth factor, insulin, granulocyte-macrophage colony-stimulating factor, interleukin (IL)-2, IL-3 and erythropoietin have been shown to induce phosphorylation of Raf-1, thereby activating Raf-1 kinase. Raf-1 is, thus, believed to play a role in coupling growth factor receptors to proliferation. We have examined the role of Raf-1 in the mitogenic response of human peripheral blood-derived IL-2 receptor expressing T cells to human recombinant IL-2 employing c-raf antisense (AS) oligodeoxyribonucleotide. Uptake studies of oligonucleotides indicated that incorporation of oligomers was maximal at 4 h and oligodeoxynucleotides remained stable in these cells for up to 24 h. Treatment of T cells with the AS oligodeoxyribonucleotide in intracellular duplex formation followed by efficient translation blockade of c-raf-1. In contrast, sense (S) and nonsense (NS) oligodeoxynucleotides failed to form intracellular duplexes and did not interfere with translation of c-raf-1, suggesting specific elimination of c-raf-1 by the AS oligomer. Proliferation of T cells ([3H]thymidine incorporation) following exposure to IL-2 was substantially reduced when the c-raf-1 AS oligodeoxyribonucleotide was added to cultures, while the mitogenic response to this factor remained almost unaffected in the presence of S and NS oligodeoxyribonucleotides.

Base Sequence↗
PubMed1993

The mitogenic response to tumor necrosis factor alpha requires c-Jun/AP-1.

In the present study, we addressed the role of the c-jun proto-oncogene in the mitogenic response of human fibroblasts and primary acute myelogenous leukemia blasts to tumor necrosis factor alpha (TNF-alpha). Our data indicate that TNF-alpha treatment of these cells is associated with transcriptional activation of c-jun, resulting in accumulation of c-jun mRNA and protein expression. In order to elucidate the role of c-Jun/AP-1 in TNF-mediated growth stimulation, the antisense (AS) technique was used. Uptake studies of oligonucleotides were performed with fibroblasts, demonstrating that incorporation of oligomers was maximal at 4 h. Oligodeoxynucleotides remained stable in these cells for up to 24 h. Treatment of fibroblasts with the AS oligonucleotide resulted in intracellular duplex formation followed by an efficient translation blockade of c-Jun/AP-1. In contrast, sense (S) and nonsense (NS) oligodeoxynucleotides failed to form intracellular duplexes and also did not interfere with translation of c-Jun/AP-1, suggesting specific elimination of c-Jun/AP-1 by the AS oligomer. Fibroblasts cultured in the presence of the AS oligonucleotide but not those cultured in the presence of the S or NS oligonucleotide failed to respond proliferatively to TNF-alpha. These findings could be confirmed by experiments with primary acute myelogenous leukemia blasts, which also demonstrated that TNF-induced growth stimulation required c-Jun/AP-1 function. Taken together, our results indicate that activation of c-Jun/AP-1 plays a pivotal role in the signaling cascade initiated by TNF, which leads to a proliferative response of its target cells.

Base Sequence↗
PubMed1993

Mithramycin selectively inhibits collagen-alpha 1(I) gene expression in human fibroblast.

The products of the collagen-alpha 1(I) and -alpha 2(I) genes form the triple helical molecule collagen type I, which constitutes the major ECM protein in tissue fibrosis. The collagen-alpha 1(I) gene is mainly transcriptionally regulated, and its promoter activity depends on the interaction of the transcription factors NF-I and Sp1 with a tandem repeat of evolutionary conserved NF-I/Sp1 switch elements. An increased affinity of Sp1 to these elements has been observed in experimental liver fibrosis. Here, we demonstrate that the DNA binding drug mithramycin displays a high affinity binding to the GC-rich elements in the collagen-alpha 1(I) promoter as measured by DNAse I protection and gel retardation assays. Mithramycin interferes with Sp1 but not with NF-I binding to these sites. At a concentration of 100 nM, mithramycin efficiently reduces basal and TGF-beta-stimulated alpha 1(I) gene expression in human primary fibroblasts. The transcriptional activity and mRNA steady state levels of other genes, including the collagenase gene, as well as the growth rate of fibroblasts remained unchanged on exposure to this drug. Taken together, our results indicate that the transcriptional activity of the type I collagen gene highly depends on its GC-rich regulatory elements, and further, that these elements can be differentially blocked, thereby changing the balance between ECM structural and degrading gene activities in human fibroblasts.

Blotting, Northern↗
PubMed1993

Modulation of cytotoxicity and differentiation-inducing potential of arabinofuranosylcytosine in myeloid leukemia cells by hematopoietic cytokines.

Hematopoietic growth factors may be useful in improving the clinical effectiveness of arabinofuranosylcytosine (ara-C). In vitro studies have indicated that interleukin 3(IL-3) and, to a lesser extent, granulocyte-macrophage colony-stimulating factor (GM-CSF), but not G-CSF or M-CSF, may be capable of specifically augmenting the ability of ara-C to kill leukemic myeloid cells by pharmacological and cytokinetic mechanisms including increase of intracellular ara-CTP/dCTP pool ratios and enhanced ara-C DNA incorporation in leukemic blast cells, decrease of IC 90 of ara-C for leukemic colony-forming cells (CFC) as compared with normal CFC growth, and recruitment of quiescent leukemic cells into the cell cycle. In contrast, the combination of ara-C with M-CSF or with the leukemia inhibitory factor (LIF) appears to be useful in overcoming the block in differentiation of leukemic blast, while the effects of GM-CSF and IL-3 on ara-C-induced differentiation appear limited. The combined treatment of human myeloid leukemia cells by ara-C and LIF is associated with down-regulation of c-myc gene expression, transcriptional activation of jun/fos gene expression, and features of functional differentiation (e.g., the capability to reduce nitroblue tetrazolium, to express lysozyme, or to display differentiation-related surface receptors including C3bi and the c-fms protein). On the basis of these in vitro studies first clinical trials are underway that are examining the efficacy of ara-C combinations with these molecules for the treatment of myeloid disorders.

Acute Disease↗
PubMed1993

Serum levels of circulating ICAM-1 are increased in Hodgkin's disease.

The intercellular adhesion molecule 1 (ICAM-1) is the ligand for the lymphocyte function-associated antigen 1 (LFA-1). The ICAM-1/LFA-1 complex mediates cell-cell and cell-matrix interactions and is believed to be crucial for several immunological functions, including non-MHC-restricted cytotoxicity. Recently, a circulating form of the surface ICAM-1 molecule, the 82 kDa cICAM, has been identified. Using enzyme-linked immunosorbent assay (ELISA) we have examined 82 kDa cICAM-1 levels in the sera of 45 age- and sex-matched healthy subjects and 130 consecutive patients with Hodgkin's disease (HD). The mean +/- SD concentration of the 82 kDa cICAM-1 was significantly higher (p < 0.001) in HD patients (725.6 +/- 141 ng/ml) than in healthy controls (403.5 +/- 54.5 ng/ml). Patients with B-symptoms (n = 66) had higher cICAM-1 levels than patients without systemic symptoms (n = 64) (825.1 +/- 202.9 ng/ml versus 671.7 +/- 164.9 ng/ml; p < 0.001). Serum levels of cICAM-1 were also significantly higher (p < 0.05) in patients with disseminated disease (stage III and IV) than in those with localized disease (stage I and II). The HD patients in stage III and IV with B-symptoms had significantly higher (p < 0.001 and p < 0.02, respectively) cICAM-1 levels then stage III/IV patients lacking B-symptoms. The increase of cICAM-1 concentrations was positively correlated to increases of soluble receptors for interleukin-2 (sIL-2R) (r = 0.69; p < 0.001). Since cICAM-1 is functionally able to bind to LFA-1, increased serum levels of this molecule could be a mechanism for promoting de-adhesion and inability of Hodgkin and Reed-Sternberg cells (H-RS) to be recognized by cytotoxic effector cells, and could thus represent a way for these cells to escape immunosurveillance and for progression and spreading of disease.

Adolescent↗
PubMed1993

N-RAS gene activation in acute myeloid leukemia: association with expression of interleukin-6.

The 21 kDa proteins encoded by RAS genes are thought to be involved in intracellular signal transduction. Expression of RAS genes activated by point mutations after transfection into mammalian cells can modulate the response of these cells to exogenously added growth factors and their expression patterns of growth factors. We analyzed leukemic cells from 50 patients with acute myeloid leukemia (AML) for the presence of activating point mutations of the N-RAS gene using polymerase chain reaction (PCR) and differential oligonucleotide hybridization. This assay allows semiquantitative determination of the relative abundance of cells carrying N-RAS mutations. Clonal activation of N-RAS, noted in the large majority of leukemic cells of the six of these patients, was correlated significantly (p = 0.0003) with the ability of these cells to express interleukin 6 (IL-6), previously shown to be expressed at high levels in approximately 30% of primary AML cells. In 16 patients, the presence of N-RAS mutations was observed only in subpopulations of leukemic cells. The 'subclonal' involvement of some but not all leukemic cells was further demonstrated by PCR analysis of individual clones grown in soft agar culture. We investigated whether additional, complementary changes in oncogene structure occurred in cells exhibiting clonal activation of N-RAS. For instance, concomitant activation of N-RAS and amplification or rearrangement of c-MYC have been observed in various tumor tissues. Southern blot analysis did not, however, reveal gross alternations of MYC gene structure or copy number in these cells.

Base Sequence↗
PubMed1993

The mitogenic response of AML blasts to tumor necrosis factor-alpha requires functional c-jun/AP-1.

The c-jun proto-oncogene belongs to the family of immediate early response genes and is inducible by serum growth factors and Tumor Necrosis Factor (TNF). In the present study we have addressed the role of c-jun for the mitogenic response of primary acute myelogenous leukemia (AML) blasts to TNF-alpha. Our data indicate that TNF-alpha treatment of these cells is associated with transcriptional activation of c-jun and accumulation of c-jun mRNA. In order to elucidate the role of c-jun for TNF-mediated growth stimulation, an antisense (AS) oligomer directed towards the translation initiation site of c-jun was instrumental. Uptake studies of oligonucleotides showed that incorporation of oligomers was maximal at 4 hours. Oligodeoxynucleotides remained stable in these cells for up to 24 hours. Treatment of AML blasts with the AS oligonucleotide resulted in intracellular duplex formation followed by efficient translation blockade of c-jun/AP-1. In contrast, sense (S) and none-sense (NS) oligodeoxynucleotides failed to form intracellular duplexes and also did not interfere with translation of c-jun/AP-1, suggesting specific elimination of c-jun/AP-1 by the AS oligomer. AML blasts cultured in the presence of AS to c-jun, but not of S or NS, failed to proliferatively respond to TNF-alpha stimulation. Taken together, our results indicate that activation of c-jun/AP-1 plays a pivotal role in the signaling cascade initiated by TNF which leads to a proliferative response of its target cells.

Base Sequence↗
PubMed1993

The significance of serum levels of soluble 60kDa receptors for tumor necrosis factor in patients with Hodgkin's disease.

Soluble forms of the two molecular species of the cell surface receptors (Rs) for tumor necrosis factor (TNF) have been detected in normal urine and serum including type I and type II TNF-Rs. Using enzyme-linked immunosorbent assay we have determined type I 60 kDa sTNF-R levels in the sera of 45 age- and sex-matched healthy subjects and 106 patients with Hodgkin's disease (HD). HD patients were either previously untreated (n = 76) or were in complete remission for at least 3 years after remission induction treatment (n = 30). The mean +/- SD concentrations of the 60 kDa type sTNF-R were significantly higher in HD patients than in healthy controls (1.32 +/- 0.19 ng/ml versus 0.6 +/- 0.13 ng/ml; p < 0.001). The extent of increase correlated with the disease stage. Soluble 60 KDa TNF-Rs were found to be significantly higher in stage III and IV (1.42 +/- 0.21 ng/ml) than in stages I and II (1.08 +/- 0.15 ng/ml). Patients with B-symptoms (n = 33) had higher levels (1.67 +/- 0.20 ng/ml) than patients without systemic symptoms (1.02 +/- 0.11 ng/ml; p < 0.001). In 52 patients evaluable for response, the complete remission (CR) rate of patients with 60 kDa sTNF-Rs < 1.2 ng/ml was higher (88%) than in those with 60 kDa sTNF-Rs > 1.2 ng/ml (64%; p < 0.01). A significant increase in serum levels of 60 kDa sTNF-R levels was also observed in HD patients in long-standing CR (1.04 +/- 0.10 ng/ml). Our data suggest that the pretreatment serum concentration of 60 kDa sTNF-Rs in HD may bear prognostic relevance. Increased 60 kDa sTNF-R levels seen in HD patients in remission may point to the defect in cellular immunity characteristic of HD patients.

Adolescent↗
PubMed1993

The Rani of Chitor: the face.

In this paper the author introduces a psychoanalytic concept: the face. This concept has two aspects: it is the particular form in which the subject's identity is revealed to him, and it also demonstrates how the analyst works in the sense of allowing the patient to discover who he is. For this purpose the author makes use of a Hindu legend, which he does not interpret conventionally but narrates, inviting the reader to learn with it. The foundations of this approach lie in the results of his research on the psychoanalytic method and in his consequent position with respect to psychoanalysis: field theory. Fixed interpretive keys are not used; the material, the legend, throws light on an aspect of psychoanalysis itself, while psychoanalysis illuminates the material. The theoretical and methodological reorganisation suggested here helps us to understand the nature of psychoanalytic interpretation and how analysis works in the investigation of the face of human desire.

Cultural Characteristics↗
PubMed1992

Prolongation of survival of human polymorphonuclear neutrophils by granulocyte-macrophage colony-stimulating factor is caused by inhibition of programmed cell death.

In the absence of appropriate stimuli, polymorphonuclear neutrophils (PMN) undergo programmed cell death (PCD), also termed apoptosis. We show that granulocyte-macrophage colony-stimulating factor (GM-CSF), but not the chemotactic factors formyl-methionyl-leucyl-phenylalanine (FMLP), recombinant human (rh) C5a, transforming growth factor (TGF)-beta, and interleukin-8 (IL-8), or other cytokines including IL-3, IL-4, IL-6, and G-CSF, maintains viability of PMN in culture by preventing these cells from undergoing PCD. Prevention from PCD by GM-CSF was associated with induction of RNA and protein synthesis in PMN. Inhibition of RNA and protein synthesis by actinomycin-D and cycloheximide impeded the protection of apoptosis by GM-CSF. Similarly, neutralization of GM-CSF biologic activity by a specific antiserum abrogated GM-CSF-mediated inhibition of PCD.

Apoptosis↗
PubMed1992

Involvement of nuclear factor-kappa B in induction of the interleukin-6 gene by leukemia inhibitory factor.

Recent studies have indicated that the leukemia inhibitory factor (LIF) induces secretion of interleukin-6 (IL-6) in myeloid cells. We here show that synthesis of IL-6 by human mononuclear phagocytes exposed to recombinant human (rh) LIF is preceded by an increase of IL-6 transcript levels as a result of transcriptional activation of the IL-6 gene. Analysis of deleted fragments of the IL-6 promoter indicated that transcriptional activation of the IL-6 promoter was associated with enhanced binding activity of the transcription factor nuclear factor (NF)-kappa B. Binding of activation protein (AP)-1 and NF-IL-6, also known to transcriptionally activate the IL-6 promoter, was not inducible by LIF. Furthermore, introduction of the NF-kappa B sequence into a heterologous promoter construct, but not of AP-1- and NF-IL-6-binding sequences, conferred inducibility by LIF to this promoter. Deletion of the NF-kappa B binding site in the IL-6 promoter was associated with loss of inducibility by LIF, lending further support for the notion that the NF-kappa B binding site is crucial for LIF-mediated induction of the IL-6 promoter. Taken together, our results show that rhLIF induces IL-6 gene expression in mononuclear phagocytes through transcriptional gene activation involving NF-kappa B.

Binding Sites↗
PubMed1992

A switch toward demethylation is associated with the expression of myeloperoxidase in acute myeloblastic and promyelocytic leukemias.

Expression of numerous genes encoding myeloid-specific proteins is tightly regulated during normal myeloid differentiation. This heterogeneous group of genes thus offers a tool for dissection of different maturational steps of myelopoiesis. We have previously shown that the human myeloperoxidase (MPO) gene is modified at numerous CpG residues in normal myeloid cells and in myeloid cell lines in a development-specific and expression-associated manner. In the present work, we have applied this type of methylation analysis to primary leukemia myeloid cell samples. We found that expression of MPO messenger RNA (mRNA) is grossly limited to leukemias of late myeloblastic and promyelocytic stages; expression is thus associated with progressive demethylation in the 5' region of the MPO gene. This modification was not global. Low-level induction of MPO mRNA expression in very immature leukemic cells using phorbol ester was not accompanied by progressive demethylation. This type of methylation analysis of a myeloid-specific gene may yield a molecular indicator for different types of myeloid leukemias.

Blotting, Northern↗