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J Lotem

Publications and source records attributed to J Lotem.

At least 73 records · Page 4Linked to original sources
PubMed1985

Screening for induction of differentiation and toxicity to blast cells by chemotherapeutic compounds in human myeloid leukemia.

Bone marrow cells from 9 patients with acute myeloid leukemia and 1 patient with a blast crisis of chronic myeloid leukemia were cultured to determine their ability to be induced to differentiate by different chemotherapeutic compounds. Five of these 10 patients showed differentiation to granulocytic and/or monocytic cells by culture with medium containing the myeloid cell differentiation-inducing protein MGI-2. Actinomycin D induced differentiation in cells from 2 of the patients who did not show differentiation with MGI-2 containing medium. In these 7 patients there was an increase in the ratio of differentiated myeloid cells to blasts. None of these 10 patients showed induction of differentiation by cytosine arabinoside, adriamycin, or daunomycin, but treatment with these compounds showed in some patients an increase in the ratio of differentiated myeloid cells to blasts. The results indicate that this ratio can be increased by differentiation and also in some patients by toxicity to blast cells. With dexamethasone or vinblastine there was no induction of differentiation and no increase in this ratio in any of the 10 patients tested. After in vivo chemotherapy with low dose cytosine arabinoside, cells from one patient showed a similar response in culture to actinomycin D as cells before chemotherapy, whereas in another patient the cells had acquired the ability to respond to actinomycin D. In contrast, after high-dose in vivo chemotherapy with cytosine arabinoside and daunomycin, cells from a third patient seemed to have lost the ability to differentiate in vitro by MGI-2 containing medium or actinomycin D. The results indicate that pre-screening for differentiation-inducing compounds and compounds that show toxicity to blast cells should be useful to select the appropriate compounds to be used for therapy, and that it is advisable to screen the cells both before and after initiation of therapy.

Antineoplastic Agents↗
PubMed1984

Control of in vivo differentiation of myeloid leukemic cells. IV. Inhibition of leukemia development by myeloid differentiation-inducing protein.

It is shown that a 5-day schedule of two injections per day of the myeloid differentiation-inducing protein MGI-2 inhibited the in vivo development of leukemia in SL and SJL/J mice with different syngeneic MGI+D+ clones of myeloid leukemic cells. With this schedule of treatment high levels of MGI-2 were maintained in the serum for long periods. In contrast to these results with MGI-2, the same schedule of injections of the myeloid growth-inducing protein MGI-I did not affect the in vivo development of leukemia in mice with MGI+D+ myeloid leukemic cells, but stimulated normal myelopoiesis in the bone marrow. Different forms of MGI-I including MGI-IM and MGI-IG had different serum half-lives, and the form of MGI-I with the shortest serum half-life showed the smallest in vivo effect on normal myelopoiesis. MGI-2 injections did not inhibit the in vivo development of differentiation-defective WEHI-3B myelomonocytic leukemic cells or YAC lymphoma cells. The results indicate that the in vivo inhibitory effect of MGI-2 on the development of myeloid leukemia correlated with its differentiation-inducing potential on the leukemic cells. It is concluded that this approach of inhibiting leukemia development by inducing differentiation should also be applied to human leukemic patients, whose cells have been shown to be inducible for differentiation in culture by human MGI-2 or by other differentiation-inducing compounds.

Animals↗
PubMed1984

Selectivity in the control of opiate receptor density in the animal and in cultured fetal brain cells.

Two aspects of the mechanisms controlling down-regulation of opiate receptors were studied: 1. The possibility that morphine does not induce down-regulation of delta receptors is an observation confined to in vitro conditions was investigated by studying the regulation of receptors in neuroblastoma-glioma cells in diffusion chambers implanted in ICR mice peritonea. Injection of morphine for 9 days at a dose inducing opiate tolerance did not change the number of receptors in the chamber-implanted cells, whereas etorphine at a 1/100 dose had a profound effect. 2. Embryonic cells from rat forebrain or hindbrain were cultured with mu type opiate alkaloid (morphine) or peptide (morphiceptin) to further establish the selectivity of opiate action. A partial effect of morphiceptin but not morphine on the number of receptors in hindbrain aggregates was observed. Thus, conclusions derived from experiments with morphine may not be applicable to mu type peptides. The results suggest that the mammalian brain may contain sub-types of mu receptors. Alternatively, although interacting with a common mu receptor, morphine and mu opioid peptides may induce different regulatory mechanisms.

Animals↗
PubMed1984

Cell differentiation and therapeutic effect of low doses of cytosine arabinoside in human myeloid leukemia.

Bone marrow cells from 2 patients over 60 years of age with acute myeloblastic (AML) or monoblastic (AMoL) leukemia were cultured in the presence of a low dose of cytosine arabinoside. In the cells from the AML patient this treatment induced differentiation to metamyelocytes and a decrease in the number of blasts, so that there was an 11-fold increase in the ratio of differentiated myeloid cells to blasts. In the patient with AMoL there was differentiation to monocytes and macrophages and only a 3-fold increase in the ratio of differentiated myeloid cells to blasts. In the latter patient actinomycin D was a more potent inducer of differentiation than cytosine arabinoside, daunomycin was similar to cytosine arabinoside and adriamycin showed the lowest response. Four courses of low dose treatment with cytosine arabinoside produced remission in the patient with AML and in another patient with AMoL whose cells were not tested in culture. No remission was induced by this low dose treatment in the patient with AMoL whose cells showed only a small decrease in blast cells in culture with cytosine arabinoside. It is suggested that prescreening for effective compounds in patients with myeloid leukemias and the use of low dose therapy can be of help in obtaining remission without serious side effects. This could be especially useful in patients where there may be severe toxic effects after high dose chemotherapy.

Aged↗
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↗
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↗
PubMed1982

Regulation of growth and differentiation by phorbol esters and the mechanism of tumor promotion.

Our studies on the growth and differentiation of normal and malignant myeloid cells have shown that tumor-promoting, but not nonpromoting, phorbol esters can induce the production of an specifically increase cell susceptibility to the normal myeloid inducers of growth and differentiation, the macrophage- and granulocyte-inducing proteins MGI. In some clones of myeloid leukemic cells, the tumor promoters induced cell differentiation via the production of MGI. In other clones that were not inducible by adding only the tumor promoters or MGI, the tumor promoters induced differentiation by increasing cell susceptibility to externally added MGI. Normal myeloid progenitor cells, unlike leukemic cells, require MGI for cell viability and multiplication. Our studies with these normal cells have shown, that tumor promoters can also induce cell multiplication both by the induction of MGI and by increasing cell susceptibility to externally added MGI. We suggest that by the above mechanisms of inducing the production and increasing cell susceptibility to normal regulators of cell multiplication and differentiation, tumor-promoting phorbol esters can exert pleiotropic effects, the nature of these effects depending on which molecules are being regulated in the treated cells.

Animals↗
PubMed1980

Separation of different molecular forms of macrophage- and granulocyte-inducing proteins for normal and leukemic myeloid cells.

It is shown that serum of mice treated with endotoxin (ES) contains three separable and functionally distinct forms of macrophage- and granulocyte-inducing (MGI) proteins. One form (MGI-1M) induced the formation of macrophage colonies from normal bone-marrow cells and showed on gel filtration an apparent molecular weight of 300,000; a second form (MGI-1G) induced the formation of granulocyte colonies from normal bone-marrow cells and had an apparent molecular weight of 45-100,000; and the third form (MGI-2) induced the normal differentiation of MGI+D+ myeloid leukemic cells to macrophages and granulocytes and had an apparent molecular weight of 28,000. Studies on the time course of the decrease of these three activities in ES have indicated that MGI-2 was more readily inactivated in vivo than MGI-1M and MGI-1G. The MGI-1M in ES isolated after gel filtration was completely neutralized by an antiserum to MGI-1 from mouse L-cells, whereas the isolated MGI-1G and MGI-2 were not affected by this antiserum. Gel filtration under dissociating conditions (6 M guanidinium chloride) resulted in a reduction of the apparent molecular weights of MGI-1M from 300,000 to 42,000, and of MGI-1G from 45-100,000 to 28,000, while it produced no change in the 28,000 apparent molecular weight of MGI-2. Similar studies with conditioned medium produced in vitro from mouse lung and peritoneal macrophages showed that in these conditioned media, MGI-1 (both G and M) in the native form had an apparent molecular weight of 41,000 and MGI-2 of 24,000, and that both MGI-1 and 2 had an apparent molecular weight of 24,000 under dissociating conditions. The results indicate that MGI-1 exists in serum in vivo and in these conditioned media as aggregated proteins, whereas MGI-2 does not, and that macrophages and lung tissue are not the only source of the MGI proteins found in ES. It is suggested that all three forms of MGI activity are derived from one precursor protein; that only the MGI-2 form assayed on leukemic cells should be used for treatment based on the induction of normal cell differentiation in myeloid leukemia; and that MGI-2 may serve as a survey mechanism for inducing differentiation in myeloid leukemic cells that have lost their responsiveness to the MGI-1 molecules that control the viability, proliferation and differentiation of normal myeloblasts.

Animals↗
PubMed1980

Potential pre-screening for therapeutic agents that induce differentiation in human myeloid leukemia cells.

A cultured line of human myeloid leukemic cells has been used, to test for the ability of compounds used in chemotherapy to induce partial or complete differentiation of these leukemic cells. The compounds differed in their ability to induce specific differentiation-associated properties. Effectiveness of induction of Fc and C3 rosettes was of the order actinomycin C greater than cytosine arabinoside greater than mitomycin-C greater than adriamycin greater than bromodeoxyuridine greater than hydroxyurea. Induction of rosettes by actinomycin-D required a 8212-fold lower concentration than induction by hydroxyurea. All these compounds, except bromodeoxyuridine, induced the synthesis and secretion of lysozyme with the same order of effectiveness as for rosettes, but only actinomycin-D and to a lesser extent bromodeoxyuridine induced the formation of mature granulocytes. Vincristine induced only a small increase in lysozyme. The results indicate that actinomycin-D was the most potent inducer of differentiation in these human myeloid leukemic cells. It is suggested that pre-screening of individual patients for the most effective compounds that can induce differentiation of their myeloid leukemic cells in culture, may prove beneficial for treatment in a form of chemotherapy based on the induction of normal differentiation in leukemic cells.

Antineoplastic Agents↗
PubMed1979

Regulation of normal differentiation in mouse and human myeloid leukemic cells by phorbol esters and the mechanism of tumor promotion.

The control of cell multiplication and differentiation by tumor-promoting phorbol esters including 12-O-tetradecanoylphorbol-13-acetate (TPA) has been studied with different clones of mouse myeloid leukemic cells, a line of human myeloid leukemic cells, and normal mouse bone marrow myeloblasts. TPA induced normal cell differentiation in one of the mouse leukemic clones and this was mediated by induction of the protein inducer of differentiation to macrophages or granulocytes (MGI) in the cells that then differentiated. Other mouse clones were not induced to differentiate by TPA. In one of these clones, TPA induced cell susceptibility to externally added MGI. This effect was not due to a general induction of susceptibility to all compounds because TPA did not induce susceptibility to lypopolysaccharide or dexamethasone in this clone. In the human leukemic cell line, TPA also induced differentiation with the induction of MGI activity and enhanced susceptibility to added MGI. It is suggested that the clonal differences in induction of MGI activity and increased susceptibility to MGI may be associated with differences in receptors for TPA and the ability of TPA to modify receptors for MGI. Studies with normal bone marrow cells have indicated that TPA stimulated MGI activity and also increased susceptibility of normal myeloblasts to induction of multiplication by MGI. The ability of different phorbol esters to produce these effects on normal myeloblasts and myeloid leukemic cells paralleled their ability to act as tumor promoters. The results indicate that a tumor promoter such as TPA can induce the production of and increase cell susceptibility to a normal regulator of cell multiplication and differentiation. TPA has pleiotropic effects. It is suggested that, by these mechanisms, TPA may thus act as a tumor promoter by increasing cell multiplication in initiated cells, induce differentiation in some cells, or inhibit differentiation in other cells, depending on which molecules are being regulated in the TPA-treated cells.

Animals↗
PubMed1978

In vivo induction of normal differentiation in myeloid leukemia cells.

MGI(+)D(+), MGI(+)D(-), and MGI(-)D(-) mouse myeloid leukemic cells, which genetically differ in their competence to be induced to undergo normal cell differentiation in vitro by the normal macrophage- and granulocyte-inducing protein MGI, were analyzed for their ability to undergo cell differentiation in diffusion chambers in vivo. As after induction by MGI in vitro, MGI(+)D(+) clones were induced for Fc and C3 rosettes, lysozyme, and mature macrophages and granulocytes in normal syngeneic or allogeneic mice. MGI(+)D(-) clones were also induced in these mice for all these properties, although in vitro they were not induced by MGI for mature cells. The MGI(-)D(-) clones were induced in vivo for C3 and Fc rosettes, lysozyme, and intermediate stages but not for mature cells, whereas none of these properties were induced in these clones by MGI in vitro. Thus, certain types of myeloid leukemic cells differentiate better in vivo, possibly due to the presence of higher effective concentrations of MGI and/or other inducing factors, and MGI(+)D(+) and MGI(+)D(-) cells can completely differentiate in vivo to mature cells. In vivo differentiation was inhibited in mice treated with cyclophosphamide. It was also inhibited in various strains of nude mice, except for one MGI(+)D(+) clone, where it was inhibited in C57BL/6 but not in ICR nude mice. This MGI(+)D(+) clone was also the only clone that was induced to differentiate normally in vitro by a 23,000 molecular weight form of purified MGI. The results suggest that different clones respond to different molecular forms of MGI, which may be present in different proportions in some animals, that in vivo differentiation by MGI possibly with other factors may be regulated by cells involved in the immune response, and that this differentiation can be genetically controlled. Differentiation in vivo was enhanced by injection of conditioned medium containing MGI and by inoculation of MGI-producing cells, including normal granulocytes. This indicates that the induction of normal differentiation of myeloid leukemic cells in vivo can be enhanced by these treatments.

Animals↗
PubMed1977

Genetic dissection of the control of normal differentiation in myeloid leukemic cells.

Normal myeloid precursors and MGI(+)D(+) myeloid leukemic cells can be induced to differentiate to mature cells by the normal protein inducer MGI. The sequence of differentiation is the induction of C3 and Fc rosettes, C3 and Fc immune phagocytosis (IP), synthesis and secretion of lysozyme, and formation of mature macrophages and granulocytes. Mutant clones of myeloid leukemic cells have been isolated with differences in the time of induction of C3 and Fc rosettes and C3 and Fc IP, in which lysozyme was induced without going through the stage of Fc or C3 IP, and with differences in inducibility by MGI to mature macrophages or granulocytes. Only one out of five MGI(-)D(-) clones gave rise to MGI(+)D(+) mutants. The ability to obtain mutants from this clone was associated with its special chromosome constitution, and these mutants showed a change in their ability for cap formation by concanavalin A. The steroid inducer dexamethasone can induce in MGI(+)D(+) clones differentiation to macrophages but not to granulocytes. Differentiation by steroid inducer in different clones occurred either with or without induction of Fc rosettes and Fc IP, and induction of C3 rosettes was not always associated with induction of C3 IP. The use of mutants that differ in their competence to be induced by MGI or steroid inducer has shown that there are separate controls for the induction of C3 and Fc rosettes, C3 and Fc IP, lysozyme, macrophages, and granulocytes.

Animals↗
PubMed1976

Control of Fc and C3 receptors on myeloid leukemic cells.

An experimental system has been developed to study in cloned lines of cells the control of Fc and C3 receptors by different compounds. The cells used were clones of mouse myeloid leukemic cells and the compounds used were the protein MGI2 (macrophage and granulocyte inducer) in serum from mice injected with bacterial endotoxin and the steroid inducer (SI) dexamethasone. Eight clones were isolated which could be divided into three groups. One group (MGI+SI+) was induced to form EA and EAC rosettes by MGI and only EAC rosettes by SI, the second group (MGI-SI+) was not inducible by MGI but was induced by SI to form EA or EA and EAC rosettes, and the third group (MGI-SI-) was not inducible for EA or EAC by MGI or SI. There were two types of MGI+SI+ clones, one type (D+) could be induced by MGI to differentiate to mature macrophages and granulocytes, and the other type (D-) could not be induced to differentiate to mature cells. The MGI-SI+ and MGI-SI- clones were all D-. The results indicate that there are different cellular sites for MGI and SI and that induction of EA and EAC rosettes did not seem to be mediated by cyclic AMP. Experiments with specifically bound 3H-BSA-anti-BSA complexes have indicated that there was an increase in the amount of 3H-BSA-anti-BSA bound per rosette-forming cell following induction by MGI or SI, and there were differences in the amount of 3H-BSA-anti-BSA bound per rosette-forming cell in different clones. These clones also showed differences in the shape of the curve for the number of EA rosette-forming cells obtained with erythrocytes coated with decreasing concentrations of antibody. The results suggest that such curves and those obtained with EAC rosettes can be used to determine the relative abundance of EA and EAC receptors on rosette-forming cells. EA rosettes on the myeloid leukemic cells, like those on normal macrophages and granulocytes, were specifically inhibited by IgG2a and by the Fc but not the Fab fragment of IgG. The EAC rosettes were inhibited by destroying the C3 component of complement. The different clones maintained their specific properties for at least 6 months in culture. The present system should, therefore, also be useful for studies on the genetic control of the regulation of Fc and C3 receptors.

Animals↗