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Biomedical subjects

L Sachs

Publications and source records attributed to L Sachs.

At least 163 records · Page 9Linked to original sources
PubMed1983

Control of in vivo differentiation of myeloid leukemic cells. III. Regulation by T lymphocytes and inflammation.

Mouse and human (HL-60) MGI+D+ myeloid leukemic cells were induced to differentiate to mature cells in diffusion chambers implanted into the peritoneal cavity of normal mice when a xenogeneic source of serum was added to the diffusion chambers. Differentiation was inhibited in immune deficient mice including congenitally athymic nude and neonatally thymectomized mice, and mice treated with cyclophosphamide, hydrocortisone, or X-irradiation. There was no such inhibition of differentiation in mice with various genetic defects in their B lymphocytes, granulocytes, erythrocytes and natural killer cells. Differentiation in cyclophosphamide-treated mice was restored by a single intravenous injection of normal spleen cells highly enriched for T lymphocytes. Conditions permissive for differentiation were associated with a higher number of eosinophils in the peritoneum that conditions that inhibited differentiation. Intraperitoneal injections of inflammatory peritoneal exudate cells, peritoneal granulocytes, or the inflammation inducer sodium caseinate, restored the ability of defective mice to induce differentiation. Injections into defective mice of the normal mouse macrophage and granulocyte differentiation-inducing protein (MGI-2) restored differentiation of the mouse myeloid leukemic cells but not of the human myeloid leukemic cells. Differentiation of normal mouse bone marrow myeloid precursors to mature cells and of differentiation-defective (MGI-D-) mouse myeloid leukemic cells to intermediate stages of differentiation were not affected by the conditions that inhibited differentiation of the MGI+D+ myeloid leukemic cells. The results indicate: 1) that the intraperitoneal accumulation of inflammatory cells, including eosinophils, can induce differentiation of MGI+D+ leukemic cells in the peritoneal cavity; 2) that this response requires T lymphocytes and can be regulated by xenogeneic serum in the chamber; 3) that in vivo differentiation of normal and MGI+D+ myeloid leukemic cells can be regulated in different ways; and 4) that the in vivo differentiation of the mouse MGI+D+ leukemic cells, human MGI+D+ leukemic cells and mouse MGI-D- leukemic cells were induced by different compounds, so that differentiation of different types of leukemic cells may be differently regulated in vivo depending on which compounds induce differentiation.

Animals↗
PubMed1983

Coupling of growth and differentiation in normal myeloid precursors and the breakdown of this coupling in leukemia.

Normal myeloid precursors are dependent on the macrophage and granulocyte growth-inducing protein MGI-1 for cell viability and multiplication. MGI-1 also induces production of the differentiation-inducing protein MGI-2, and this induction of a differentiation-inducing protein by a growth-inducing protein provides a mechanism for the normal coupling of growth and differentiation. It is shown that this induction of MGI-2 by MGI-1 occurs in the myeloid precursors and not in some other cells in the normal bone marrow, that the induced MGI-2 can be detected 6 h after the addition of MGI-1, and that MGI-2 can be induced in these cells by purified MGI-1. There are clones of myeloid leukemic cells that no longer require MGI-1 for cell viability and multiplication, but in which this requirement for MGI-1 can be restored after induction of differentiation by MGI-2. A similar concentration of MGI-1 was required for the optimum induction of growth in these differentiating leukemic cells and in normal myeloid precursors. In the presence of MGI-1 these differentiating leukemic cells multiplied and then lost their differentiation-associated properties. In contrast to normal myeloid cells, MGI-1 did not induce MGI-2 in the MGI-1 requiring differentiating myeloid leukemic cells. This lack of induction of MGI-2 by MGI-1 occurred in cells cultured in serum-containing or serum-free-medium, and can explain the loss of differentiation-associated properties. The results indicate that there has been a genetic breakdown of the normal coupling mechanism between growth and differentiation in these leukemic cells so that MGI-1 can no longer induce MGI-2.

Animals↗
PubMed1983

Control of endogenous cell regulators by the second-stage tumor promoter phorbol-12-retinoate 13-acetate.

The phorbol esters phorbol 12-retinoate 13-acetate (RPA) and 12-O-tetradecanoyl phorbol 13-acetate (TPA) were used to investigate the role of tumor promoters in the control of hormone response in normal and leukemic myeloid cells. RPA and TPA inhibited the binding of [20-3H]phorbol 12,13-dibutyrate to the leukemic cells in a competitive manner with 50% inhibition values of 5.2 +/- 1.3 and 1.1 +/- 0.6 nM, respectively. RPA, like TPA, enhanced (1) prostaglandin E1-induced cyclic AMP synthesis, (2) the differentiation of leukemic cells induced by the normal myeloid differentiation-inducing protein, and (3) the formation of normal myeloid cells colonies induced by the normal myeloid growth-inducing protein. Both compounds can thus control endogenous cell regulators. Since RPA functions in the second stage of tumor promotion in mouse skin, it is suggested that the control of such endogenous regulators may involve biochemical pathways similar to those that are activated in the second stage of tumor promotion.

Animals↗
PubMed1983

Synchrony of gene expression and the differentiation of myeloid leukemic cells: reversion from constitutive to inducible protein synthesis.

There are mutant myeloid leukemic cells that cannot be induced to differentiate in serum-free culture medium, or medium with calf serum by the macrophage and granulocyte differentiation-inducing protein (MGI-2) that induces differentiation in normal myeloid cells. These mutants can be induced to differentiate by MGI-2 in medium with mouse serum. The mechanism of this induction of differentiation has been analysed by using two-dimensional gel electrophoresis to study changes in the synthesis of cytoplasmic proteins. In calf serum, 46 of the protein changes that were induced by MGI-2 in normally differentiating cells were constitutive in the differentiation-defective mutant cells. Treatment with mouse serum reverted 13 of these proteins from the constitutive to the non-constitutive state. This reversion was associated with a gain of inducibility for various differentiation-associated properties, so that 23 proteins were induced by MGI-2 for the same type of change as in normal differentiation. A normal developmental program requires synchrony of gene expression. The existence of constitutive instead of inducible gene expression can produce asynchrony in this program and thus produce blocks in differentiation. The results indicate that it is possible to treat these mutant cells so as to induce the reversion of specific proteins from the constitutive to the non-constitutive state, and that this can then restore the synchrony required for induction of differentiation. It is suggested that this mechanism may also allow induction of differentiation in other types of differentiation-defective cells.

Animals↗
PubMed1983

DNA-binding protein that induces cell differentiation.

Macrophage and granulocyte-inducing (MGI) proteins regulate the growth and differentiation of myeloid hematopoietic cells. One class of these proteins (MGI-1) induces cell growth and another class (MGI-2) induces cell differentiation. Results obtained with DNA-cellulose column chromatography have shown that the differentiation-inducing protein MGI-2 can bind to double-stranded cellular DNA, but that there was no such binding under the same conditions by the growth-inducing protein MGI-1. DNA binding may thus be used to separate MGI-2 from MGI-1. The MGI-2 from mouse bound to DNA from mouse and calf. There were different elution peaks of the MGI-2 bound to DNA suggesting a heterogeneity of MGI-2 molecules, and the last peak eluted from the DNA cellulose column was enriched for one of the molecular forms of MGI-2. After one further step of purification by polyacrylamide gel electrophoresis, this molecular form of MGI-2 was active at a concentration of 6.5 X 10(-11) M. In normal development MGI-1 induces MGI-2. This induction of a DNA-binding differentiation-inducing protein by a growth-inducing protein is an efficient mechanism for the normal coupling of growth and differentiation. It is suggested that this may also be a mechanism for the normal coupling of growth and differentiation in other types of cells.

Cell Differentiation↗
PubMed1983

Klippel-Trenaunay-Weber syndrome: appearance in utero.

We were able to detect hemihypertrophy of a fetus in a routine prenatal ultrasound examination. The presence of hemangiomas and varicose veins in the hypertrophied left lower extremity at birth enabled us to diagnose the Klippel-Trenaunay-Weber syndrome. The possibility of a congenital arteriovenous fistula causing the constellation of findings was ruled out by a nuclear flow study and a thorough physical examination. A computerized tomographic scan revealed that the hemangiomas were superficial in the hypertrophied left lower extremity and did not interrupt the deep muscle bundles.

Adult↗
PubMed1982

A highly specific aminotripeptidase of rat brain cytosol. Substrate specificity and effects of inhibitors.

An aminopeptidase preferentially hydrolyzing Leu- or Ala-Gly-Gly was purified from rat brain cytosol and detailed studies have been performed on its substrate specificity and the effects of inhibitors. The enzyme was devoid of di- and oligopeptidase contamination. Biologically active tripeptides such as Met-Leu-Tyr (chemotactic factor), Gly-His-Lys (liver growth factor) and Thr-Val-leu central nervous system tripeptide) were hydrolyzed at rates 0.05-0.15-times that of Leu-Gly-Gly. Melanostatin (Pro-Leu-GlyNH2) did not serve as a substrate. Substrates bearing N-terminal charged groups, or ones with proline in positions 2 or 3, or those with D-amino acid in positions 1 or 2, or with C-terminal CONH2, were poorly hydrolyzed or did not act as substrates, providing information on subsites involved in enzyme catalysis. The enzyme was inhibited competitively by bestatin (Ki 10-7 M) and by Captopril (2.5.10-7 M, D-3-thio-2-methylpropanyl proline) and by low concentrations of Zn2+ or PCMB, and at higher concentrations by TPCK and PMSF. Inhibition was observed for the chemotactic factor (I50 13 microM) and for the central nervous system tripeptide (195 microM). The enhanced action of Captopril was attributed to the presence of the -SH and -CH3 groups, since inhibition was shared by di- and tripeptides with proline in positions 2 and 3. The specificity pattern of brain enzyme was different from that reported for kidney and intestine.

Amino Acid Sequence↗
PubMed1982

Role of phospholipase A2 and prostaglandin E in growth and differentiation of myeloid leukemic cells.

Phospholipase A2 activity and prostaglandin E synthesis have been studied in different clones of myeloid leukemic cells, which differ in their competence to be induced to differentiate by the macrophage and granulocyte differentiation-inducing protein or the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA). Clones that could be induced to differentiate by this protein showed a higher basal phospholipase A2 activity than clones that could not be induced to differentiate by this protein inducer. Cell competence to be induced to differentiate by TPA did not show this correlation, and the clone with the least ability to respond to TPA showed the lowest number of binding sites for [20-3H]phorbol 12,13-dibutyrate. Differentiation induced by the protein was accompanied by a 7-14-fold increase in prostaglandin E synthesis, whereas differentiation induced by TPA did not show this increase. Externally added prostaglandin E1 did not induce differentiation but inhibited cell proliferation and the degree of inhibition in the different clones was related to the basal phospholipase A2 activity. The results indicate that increase of prostaglandin E synthesis was not an essential pre-requisite for differentiation, that prostaglandin E seems to be involved in the inhibition of cell proliferation in association with phospholipase A2, and that the differentiation-inducing protein and TPA can induce differentiation by different pathways. The amount of basal phospholipase A2 activity was also related to previously found differences in the ability of the clones to develop desensitization to beta-adrenergic hormones or prostaglandin E1.

Animals↗
PubMed1982

Enhancement of hormone action by a phorbol ester and anti-tubulin alkaloids involves different mechanisms.

The tumor-promoting phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) enhanced 1-isoproterenol and prostaglandin E1 stimulated cyclic AMP formation in clones of mouse myeloid leukemic cells. The enhancement was found up to 3h after TPA treatment and had disappeared after 24h, indicating its reversibility. The effect of TPA was not inhibited by removal of extracellular Ca2+ or pre-treatment with the calcium ionophore A23187. This enhancement by TPA seems to involve a different pathway than enhancement of response to the same hormones after treatment with the anti-tubulin alkaloids colchicine or vinblastine, since a myeloid leukemic cell mutant clone that was non-responsive to the anti-tubulin alkaloids responded to TPA. Furthermore, combined treatment of colchicine-sensitive cells with TPA and colchicine showed an additive stimulating effect. The enhancement of cell response to hormones by TPA was found in myeloid leukemic cell clones that either were or were not induced to differentiate after treatment with TPA. This suggests that enhancement of the effect of these and possibly other hormones by TPA may be an initial step of TPA action, but that this enhancement is not sufficient to induce the wide repertoire of TPA effects including induction of differentiation.

Alprostadil↗
PubMed1982

Regulation and role of different macrophage-and granulocyte-inducing proteins in normal and leukemic myeloid cells.

It has previously been shown that there are different molecular forms of macrophage-and granulocyte-inducing (MGI) proteins; one form, MGI-l, induced the formation of colonies with differentiated cells from normal myeloblasts and another form, MGI-2, induced normal differentiation in MGI+D+ leukemic myeloblasts that no longer require MGI-l to form colonies. The present results indicate that MGI-2 can also induce differentiation (without inducing colony formation) in the normal cells, and that MGI-l induced MIG-2 in the normal but not in the leukemic cells. It is suggested from these results that MGI-2 is the differentiation-inducing protein for normal and leukemic cells whereas MGI-l is the growth-inducing protein that induces colony formation by the normal cells, and that induction of differentiation in the normal cell colonies is due to induction of MGI-2 by MGI-l.

Animals↗
PubMed1982

Autoinduction of differentiation in myeloid leukemic cells: restoration of normal coupling between growth and differentiation in leukemic cells that constitutively produce their own growth-inducing protein.

Growth and differentiation of normal myeloid haematopoietic cells are regulated by a family of macrophage- and granulocyte-inducing (MGI) proteins. Some of these proteins (MGI-1) induce cell growth and others (MGI-2) induce cell differentiation. Addition of MGI-1 to normal myeloid cells induces growth and also induces the endogenous production of MGI-2. This induction of differentiation-inducing protein by growth-inducing protein then ensures the coupling between growth and differentiation found in normal cells. There are myeloid leukemic cells that constitutively produce their own MGI-1, but the cells do not differentiate in culture medium containing horse or calf serum. By removing serum from the medium, or in medium with mouse or rat serum, these leukemic cells are induced to differentiate to mature cells, which like normal mature cells, then no longer multiply. Leukemic cells with constitutive production of MGI-1 continuously cultured in serum-free medium with transferrin were also induced to differentiate by removing transferrin. This induction of differentiation was in all these cases associated with the endogenous production of MGI-2 by the cells. The results indicate that changes in specific constituents of the culture medium can result in autoinduction of differentiation in these leukemic cells due to restoration of the induction of MGI-2 by MGI-1, which then restores the normal coupling of growth and differentiation.

Animals↗
PubMed1982

Control of growth and normal differentiation in leukemic cells: regulation of the developmental program and restoration of the normal phenotype in myeloid leukemia.

The origin and evolution of malignancy involves a sequence of genetic changes. Evidence has, however, been obtained with various types of tumors that malignant cells have not lost the genes that control normal growth and differentiation. An in vitro cloning and cell culture system has been developed to determine and dissect the controls that regulate normal myeloid cell growth, differentiation, and malignancy and to suggest a new approach to the therapy of myeloid leukemia based on the induction of normal differentiation in malignant cells. Experiments on induction of normal cell differentiation and restoration of the normal phenotype in myeloid leukemia by the physiological inducer of differentiation, the appropriate molecular form of the macrophage and granulocyte-inducing protein MGI, have also been used to formulate a general model for regulation of developmental programs and the origin and evolution of the malignancy.

Animals↗
PubMed1982

Mechanisms that uncouple growth and differentiation in myeloid leukemia cells: restoration of requirement for normal growth-inducing protein without restoring induction of differentiation-inducing protein.

There are different macrophage- and granulocyte-inducing (MGI) proteins. Normal myeloid precursors are induced to multiply by one form (MGI-1) and to differentiate by another form (MGI-2). There are clones of myeloid leukemia cells that no longer require MGI-1 for growth but can still be induced to differentiate by MGI-2. After induction of differentiation in these leukemia cells by adding MCI-2 or inducing endogenous production of MGI-2 by lipopolysaccharide, the differentiating leukemia cells, like normal cells, again required MGI-1 for growth. This growth requirement for MGI-1 could not be substituted for by adding other protein growth factors such as epidermal, fibroblast, or nerve growth factor or insulin. Induction of differentiation in these leukemia cells by dexamethasone, arabinonucleoside (cytosine arabinoside), or methotrexate instead of by MGI-2, did not restore the requirement of MGI-1 for growth. Mutant myeloid leukemia cells that could not be induced to differentiate by MGI-2 also did not show this restoration of the requirement of MGI-1 for growth. MGI-1 in normal cells induced cell growth and also induced MGI-2, so that the cells could then differentiate by the endogenously produced MGI-2. However, MGI-1 did not induce production of MGI-2 in the leukemia cells, even though they again required MGI-1 for growth, so that there was no induction of differentiation after adding MGI-1. This lack of induction of differentiation-inducing protein by growth-inducing protein has thus identified an effective mechanism for uncoupling of growth and differentiation in malignant cells.

Animals↗