N-ras gene point mutations in childhood acute lymphocytic leukemia correlate with a poor prognosis.

Ras genes can be altered by point mutations at critical portions of their coding regions to acquire transforming ability in vitro. These point mutations have been detected in a variety of human malignancies. However, their relevance for the clinical and biologic behavior of the subgroups of patients exhibiting these mutations in unclear.

Production of 1 alpha,25-dihydroxyvitamin D3 by hematopoietic cells.

Perhaps, 1 alpha,25(OH)2D3 plays a role as a co-factor in the communication between lymphocytes and macrophages. A schematic representation of that proposed interaction is shown in Figure 2. (Formula: see text).

Expression of retinoic acid receptor mRNA in hematopoietic cells.

Retinoic acid (RA) has profound effects upon the proliferation and differentiation of many hematopoietic cells. The mechanism by which RA acts is unclear. Recently, several retinoic acid receptors (RAR) have been cloned.

Role of lymphotoxin in expression of interleukin 6 in human fibroblasts. Stimulation and regulation.

IL-6 is a cytokine with a number of biological functions, including stimulation of immunoglobulin synthesis and proliferation of early hematopoietic stem cells. We showed that lymphotoxin stimulated accumulation of IL-6 mRNA in human fibroblasts (W138) in a dose-responsive fashion; tumor necrosis factor-alpha (TNF-alpha) was about threefold more potent than lymphotoxin. Further experiments suggested that stimulation by lymphotoxin was independent of protein kinase C activity, did not require new protein synthesis, and was at least in part a result of increased stabilization of IL-6 mRNA.

Lymphotoxin: stimulation and regulation of colony-stimulating factors in fibroblasts.

Colony-stimulating factors (CSFs) are pivotal for proliferation and function of hematopoietic cells. We found that lymphotoxin, a product of activated lymphocytes, stimulates accumulation of granulocyte-macrophage (GM)-CSF and macrophage (M)-CSF proteins and mRNAs in fibroblasts. An increase in GM- and M-CSF mRNA levels occurred within 2 hours after addition of 1,000 U/mL lymphotoxin and levels plateaued over the next 24 hours.

Multiple mechanisms control the expression of granulocyte-macrophage colony-stimulating factor by human fibroblasts.

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) has in vitro and in vivo effects on hemopoiesis and enhances the function of circulating mature myeloid cells. Unstimulated fibroblasts show low level GM-CSF transcription but no accumulation of GM-CSF mRNA or protein, whereas fibroblasts stimulated by TNF-alpha, IL-1, and phorbol diester have been shown to produce and secrete GM-CSF. To determine the mechanisms controlling the expression of GM-CSF in human fibroblasts, we used a transient transfection assay to look at the effect of TNF-alpha, IL-1 and phorbol diester on GM-CSF promoter sequences.

Granulocyte-macrophage colony-stimulating factor: signals for its mRNA accumulation.

Granulocyte-monocyte colony-stimulating factor (GM-CSF) is an important hematopoietic growth factor. Mesenchymal cells produce abundant GM-CSF in response to tumor necrosis factor alpha (TNF). We wished to determine (1) what cellular pathways enhanced levels of GM-CSF mRNA, and (2) if TNF used any of these pathways.

Novel vitamin D analogs that modulate leukemic cell growth and differentiation with little effect on either intestinal calcium absorption or bone mobilization.

Induction of terminal differentiation of leukemic and preleukemic cells is a therapeutic approach to leukemia and preleukemia. The 1 alpha, 25-dihydroxyvitamin D3 [1,25(OH)2D3], the hormonally active form of vitamin D3, can induce differentiation and inhibit proliferation of leukemia cells, but concentrations required to achieve these effects cause life-threatening hypercalcemia. Seven new analogs of 1,25(OH)2D3 were discovered to be either equivalent or more potent than 1,25(OH)2D3 as assessed by: (a) inhibition of clonal proliferation of HL-60, EM-2, U937, and patients' myeloid leukemic cells: and (b) induction of differentiation of HL-60 promyelocytes.

Regulation of levels of IL-1 mRNA in human fibroblasts.

Interleukin-1 (IL-1) has a crucial role in host defenses, inflammatory processes, and tissue homeostasis. A wide variety of cells produce this protein in response to a number of extracellular stimuli including microorganisms, antigenic stimuli, and products from other cells. Regulation of IL-1 production at the molecular level is poorly understood.

Evidence for a pretranslational defect in hereditary and acquired myeloperoxidase deficiency.

Myeloperoxidase (MPO) is a heme containing enzyme involved in the oxygen-dependent microbicidal activity of human polymorphonuclear leukocytes (PMN). Complete hereditary and acquired MPO deficiencies are defined as lack of peroxidase activity in PMN. Using this criterion, we studied a patient with complete hereditary MPO deficiency, and a MPO deficient variant cell line of HL-60 (HL-60-A7), which we used as a model for acquired MPO deficiency.

Expression, methylation and chromatin structure of the p53 gene in untransformed and human T-cell leukemia virus type I-transformed human T-lymphocytes.

p53 is a nuclear protein associated with cellular transformation and normal cellular proliferation. Some transformed cells have been found to have one or several quantitative or qualitative abnormalities of p53. We studied expression, kinetics, phosphorylation, DNA methylation and chromatin structure of p53 in resting and proliferating untransformed T-lymphocytes and in human T-cell leukemia virus type I transformed T-lymphocytes from the same individuals.

Modulation by retinoids and interferons of alkaline phosphatase activity in granulocytes induced by granulocyte colony-stimulating factor.

We have previously shown that a factor termed NAP-IF has the capacity to induce neutrophil alkaline phosphatase (NAP) in postmitotic granulocytes (PMGs). Recently, this factor found in cystic fluid of a human squamous cell carcinoma was shown to be identical to granulocyte colony-stimulating factor (G-CSF). In this study we examined whether NAP activity inducible with G-CSF could be modulated by other factors that are present in vivo or those that are known to induce differentiation of hemopoietic cells.

Rearrangement and expression of beta-T-cell receptor and immunoglobulin genes in established Ph1 chronic myelogenous leukemia cell lines.

We have determined the arrangement and expression of immunoglobulin (Ig) and beta-T-cell receptor (TCR) genes in six established Philadelphia chromosome-positive (Ph1) chronic myelogenous leukemia (CML) cell lines, and correlated these results with their phenotypic characteristics. Three cell lines with nonlymphoid characteristics, EM2, EM3, and K562, did not demonstrate rearrangement or expression of Ig or beta-TCR genes. A new cell line, MB, with a mature B-cell phenotype recently established in our laboratory, contained light and heavy chain immunoglobulin gene rearrangements and expressed mature Ig RNA.

A Ph1 chromosome positive B cell line expresses the fusion protein P 210.

We established a B lymphocyte line from bone marrow cultures of a patient with Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia. The cell line (MB) is positive for Ph1 and has the phenotype of mature B lymphocytes transformed by the Epstein-Barr virus (EBV). When DNA was isolated and hybridized to specific cDNA probes, a rearranged immunoglobulin gene and EBV-sequences were detected.

Identification of neutrophil alkaline phosphatase-inducing factor in cystic fluid of a human squamous cell carcinoma as granulocyte colony-stimulating factor.

We have previously shown that a factor termed neutrophil alkaline phosphatase-inducing factor (NAP-IF) has the capacity to induce neutrophil alkaline phosphatase (NAP) in postmitotic granulocytes (PMGs). This factor has characteristics similar to those of granulocyte colony-stimulating factor (G-CSF), suggesting that the two factors assayed by different methods may be attributable to an identical macromolecule. In a preliminary experiment, we showed that purified natural G-CSF (nG-CSF) could induce NAP in vitro in the presence of 10% (v/v) fetal calf serum (FCS).

Regulation of gene expression of myeloperoxidase during myeloid differentiation.

Myeloperoxidase (MPO) is a major heme enzyme involved in inflammatory responses of polymorphonuclear leukocytes. Using cDNA and intron specific probes for MPO we studied the regulation of MPO expression during myeloid differentiation of the promyelocytic HL-60 leukemia cell line. Mature MPO mRNA species of 3.

Transcriptional and posttranscriptional modulation of myeloid colony-stimulating factor expression by tumor necrosis factor and other agents.

Granulocyte (G) and granulocyte-macrophage (GM) colony-stimulating factors (CSF) are necessary for proliferation and differentiation of myeloid hematopoietic cells. Fibroblasts stimulated by tumor necrosis factor alpha (TNF alpha) and several other agents are a rich source of these CSF. The GM-CSF synthesized by these cells had the same molecular weight and glycosylation pattern as that produced by activated T lymphocytes, as shown by [35S]methionine labeling studies.

1,25-Dihydroxyvitamin D3 modulates the expression of a lymphokine (granulocyte-macrophage colony-stimulating factor) posttranscriptionally.

We recently showed that 1,25(OH)2D3 sensitively inhibited the expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) in normal human mitogen-activated peripheral blood lymphocytes and in the human T lymphotropic virus I immortalized T cell line known as S-LB1 at the levels of both mRNA and protein. Using S-LB1 cells as a model system the present paper identifies at least in part the mechanisms by which 1,25(OH)2D3 regulates the expression of GM-CSF. Time-course studies demonstrated that by 6 and 48 h of exposure of S-LB1 cells to 1,25(OH)2D3 (10(-8) M) the GM-CSF mRNA levels were reduced by 50 and 90%, respectively.

Myeloid cell lines: tools for studying differentiation of normal and abnormal hematopoietic cells.

Acute myeloid leukemia is caused by one or several transforming events which usually result in a block of myeloid precursor cell maturation. Human cell lines can serve as model for hematopoietic cells arrested at different stages of myeloid differentiation. These homogeneous populations help to dissect the cellular and molecular events involved in leukemogenesis, such as proto-oncogene activation.

Recombinant gibbon interleukin-3 acts synergistically with recombinant human G-CSF and GM-CSF in vitro.

Recombinant gibbon interleukin-3 (IL-3) is a multilineage hematopoietic colony-stimulating factor (CSF) that recently was cloned and found to be highly homologous with human IL-3. Gibbon IL-3, as well as human granulocyte-CSF (G-CSF) and human granulocyte-macrophage CSF (GM-CSF), stimulated normal human bone marrow cells to form myeloid colonies in soft agar in a sigmoidal dose-response manner. When IL-3 was added to increasing concentrations of G-CSF or GM-CSF, synergistic colony formation occurred as compared with the effects of each CSF alone.

Modulation of Mr 53,000 protein with induction of differentiation of human neuroblastoma cells.

LA-N-5 human neuroblastoma cells were found to express high levels of an Mr 53,000 cellular tumor antigen (p53), a protein that has been implicated as playing a fundamental role in the control of cell division and differentiation processes in a variety of tumor systems. When LA-N-5 cells are treated with retinoic acid, they undergo growth and morphological, biochemical, and electrophysiological changes that are characteristic of neuronal maturation and a reduction of the malignant phenotype. We find that these retinoic acid-induced changes are accompanied by a marked decrease in the levels of p53 and p53 mRNA.

p53 in chronic myelogenous leukemia. Study of mechanisms of differential expression.

The p53 is a nuclear protein that is associated with normal cellular proliferation and can cooperate with Ha-ras in causing cellular transformation in vitro. Lineage association is known to exist between p53 expression and normal lymphopoiesis, but not myelopoiesis. We studied the expression of p53 using chronic myelogenous leukemia (CML) cell lines, somatic hybrids of these cells, and leukemic cells from CML patients.