Showing papers on "Friend leukemia published in 1980"

Action of dihydroxyanthraquinone on cell cycle progression and survival of a variety of cultured mammalian cells.

Abstract: Dihydroxyanthraquinone, 1,4-dihydroxy-5,8-bis{{{2-[(2-hydroxyethyl)amino]ethyl}amino}}-9,10-anthracenedione (NSC 279836), was observed to alter the cell cycle kinetics of a variety of mammalian cell lines as monitored by flow cytometry. Continuous exposure of Friend leukemia, L1210, and Chinese hamster cells to the drug in vitro at concentrations of 1.0 to 10 ng/ml resulted in the accumulation of cells in G2 by 24 hr in culture. When cells were exposed to dihydroxyanthraquinone for 30 min, washed free of drug, and cultured in fresh medium for 24 hr, a 10 times higher drug concentration was required to produce a G2 block identical to that observed during continuous exposure. Stimulation of human lymphocytes by phytohemagglutinin could be inhibited in a dose-dependent manner by brief pretreatment of cells with the drug. However, while previously stimulated but as yet noncycling lymphocytes were profoundly affected by much lower concentrations, proliferating lymphocytes were refractory to treatment with the drug up to a concentration of 1 µg/ml. Exposure to the drug for 24 hr, at concentrations as low as 3.2 ng/ml, inhibited colony formation of exponentially growing Chinese hamster cells by 50%, whereas stationary culture required an 8-fold higher concentration to produce the same results. Drug concentrations in the range of 0.3 to 0.8 µg/ml over a period of 24 hr reduced the viability of Friend leukemia and L1210 cells by 50% as measured by trypan blue dye exclusion. In contrast, human lymphocyte viability was only mildly affected following 24 hr incubation with up to 5.0 µg dihydroxyanthraquinone per ml. There was a marked effect on cellular RNA content in two of the cell lines tested. Friend leukemia and L1210 cells blocked in G2 by the drug manifested a 140 and 70% increase in RNA content, respectively, when compared to control cells. In addition, though suboptimal concentrations of the drug resulted in a transient accumulation of cells in G2, optimal drug concentrations not only blocked cells in G2 but in the case of Friend leukemia and L1210 cells led to an increase in the proportion of cells with greater than 4C amounts of DNA. The results obtained with dihydroxyanthraquinone were compared to those obtained previously with a nonhydroxylated analog, anthracenedione (NCS 287513).

Effects of ellipticine on cell survival and cell cycle progression in cultured mammalian cells.

Abstract: The effects of ellipticine [5,11-dimethyl-6 H -pyrido(4,3- b )carbazole; NSC 71795] on cell viability, growth, and colony formation were investigated in suspension (Friend leukemia and L1210) and adherent [Chinese hamster ovary (CHO)] tumor cell systems as well as in mitogen-stimulated human peripheral blood lymphocyte cultures. Cell cycle progression and the terminal point of action of the drug were monitored by flow cytometry. Ellipticine was cytostatic for all cell lines tested, blocking cells in G2 phase following 24 hr constant exposure at concentrations in the range of 1.0 µg/ml. A 10 times higher drug concentration was required to block cells in G2 if the cells were exposed for only 30 min to the drug followed by 23.5 hr culture in drug-free medium. Formation of CHO cell colonies was inhibited by 50% following exposure to ellipticine for 2 hr at 6.0 µg/ml or for 24 hr at 0.3 µg/ml. Fifty % cell kill in asynchronously growing Friend leukemia and L1210 cells was obtained following exposure to ellipticine for 24 hr at 2.0 µg/ml and 1.15 µg/ml, respectively, whereas human peripheral blood lymphocytes required 66 hr exposure to 1.0 µg/ml to kill 50% of the cells. Phytohemagglutinin-stimulated lymphocytes were remarkably resistant to the cytotoxic effect of ellipticine but did display a dose-dependent inhibition of stimulation and accumulation in G2 whether the drug was added prior to or during active cell proliferation. Ellipticine, at cytostatic concentrations, had a marked effect on cellular RNA content. Friend leukemia cells, blocked in G2 by the drug, doubled their RNA content compared to control cells. L1210 and CHO cells, but not lymphocytes, also increased in RNA content following ellipticine treatment. Drug concentrations which blocked cells in G2 also led in the case of Friend leukemia and L1210 but not CHO cells to an increase in the proportion of cells with greater than 4C amounts of DNA.

A new class of inhibitors of lymphocyte mitogenesis: agents that induce erythroid differentiation in Friend leukemia cells.

Abstract: Addition of the polar organic compounds, dimethylsulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and butyric acid, to human lymphocyte cultures stimulated with the tumor-promoting agent, phorbol myristate acetate, results in greater than 90% inhibition of lymphocyte proliferation. Inhibition is achieved at concentrations of the organic compounds reported to be optimal for induction of erythroid differentiation in Friend leukemia cells. Butyric acid is the most potent compound tested. Compounds that are structurally related to butyric acid, but that do not induce erythroid differentiation, do not inhibit lymphocyte mitogenesis. Lymphocyte responses to other mitogens are also suppressed by the polar organic compounds, although higher concentrations are required. These agents are much less inhibitory when added 24 hr after initiation of the cultures, indicating that they may affect an early phase of lymphocyte activation. Compounds that induce erythroid differentiation in Friend leukemia cells constitute a new class of inhibitors of lymphocyte mitogenesis.

Enhancement of Viral Gene Expression in Friend Erythroleukemic Cells by 12-O-Tetradecanoylphorbol-13-acetate

Abstract: Tumor-promoting agents are known to inhibit the specific differentiation processes of several animal cell systems in vitro , including the Friend leukemia cell system. We have examined the effect of 12- O -tetradecanoylphorbol-13-acetate (TPA) on the latter system and have investigated its action on Friend virus expression. At a concentration of 16.7 nm, TPA inhibits the dimethyl sulfoxide-induced Friend cell terminal differentiation and, at the same time, enhances the expression of the Friend virus genome, as demonstrated by a 2-fold increase in the amount of reverse transcriptase-containing particles released into the culture fluid and in the levels of virus-specific intracytoplasmic RNA. The greatest effect of TPA is evident after 24 hr of treatment. At this time, TPA exerts also its strongest effect upon the induction of the plasminogen activator. Our results indicate that two specific effects of TPA, i.e. , block of differentiation and induction of plasminogen activator, correlate well in the Friend cell system with an extracellular and intracellular increase in virus expression.

Effects of 9,10-Anthracenedione, 1,4-bis[[2-[(2-hydroxyethyl)amino]-ethyl]amino]-, diacetate on Cell Morphology and Nucleic Acids of Friend Leukemia Cells

Abstract: Treatment of Friend leukemia cells for 18 hours with 9,10-anthracenedione, 1,4-bis[[(2-hydroxyethyl)amino]ethyl]amino]-, diacetate (ANT) at concentrations up to 1.0 microgram/ml induced significant changes in cell metabolism and structure. Alterations in cell nucleic acid content were detected in cells stained with acridine orange under conditions such that DNA and RNA contents could be measured simultaneously by flow cytometry. Cells treated for 18 hours with ANT at concentrations of 0.05-0.1 microgram/ml became partially blocked at the G2 phase. In addition, about 30% of the cells became polyploid and demonstrated diplochromosomes at the 8C level of mitosis. The nuclear chromatin of blocked cells had an altered structure as reflected by a change in sensitivity of DNA in situ to denaturation induced by low pH. All viable cells treated with ANT for 18 hours at concentrations of 0.4-1.0 microgram/ml were blocked in G2 phase. These cells had significantly more RNA than did untreated cells. Transmission electron microscopic observations of thin-sectioned cells suggested that this increased RNA content in ANT-treated cells was mostly due to an approximately 50% increased cell diameter and partly due to a disproportionate increase in nucleolar size. In addition, electron microscopy revealed that ANT caused increased chromatin condensation and granulation. The drug had no apparent effect on production of the endogenous Friend murine leukemia virus.

Measurement of a stimulatory protein of RNA polymerase II in various mouse organs by the complement fixation test.

Abstract: The amount of S-II, a protein specifically stimulating RNA polymerase II, was measured in various mouse organs by a micro complement fixation assay. The amount was almost the same in brain, liver, kidney, spleen, and Ehrlich ascites tumor cells on the basis of DNA, being about 3.8 micrograms/mg DNA, which corresponds to 3.6 X 10(5) molecules/cell. However, the amount of S-II decreased greatly during erythro-differentiation of Friend leukemia cells and no S-II was detected matured erythrocytes.

Antiviral and interferon-inducing properties of interferon inducers administered with prostaglandins.

Abstract: Prostaglandins enhanced the interferon response and therapeutic activity of interferon inducers in Friend leukemia virus-infected mice. A similar enhancement in interfron responsiveness but not antiviral activity was observed in mice infected with rapidly acute viruses.

Donor cell leukemia after bone marrow transplantation in the Friend leukemia in mice.

Abstract: After lethal irradiation (800 R) Friend virus (FV-P)-infected leukemic DBA/2 mice were transplanted with normal bone marrow cells. Isogeneic transplantation led to an immediate relapse of leukemia. Therefore, allogeneic bone marrow cells were taken from almost FV-P resistant C57BL/6 mice. A measure of leukemia development was given by the number of erythropoietin-independent erythroid colonies (CFU-EI) in bone marrow and spleen, characteristic for the Friend leukemia. Even after allogeneic transplantation leukemia recurred after 5 to 19 days. By an electrophoretic analysis of the hemoglobin, it could be shown that the transformed erythropoiesis was donor derived. Thus, marrow of C57BL/6 origin loses its FV-P resistance in allogeneic leukemic lethally irradiated recipients and is transformed by the surviving virus.

Effects of tilorone on hemopoietic stem cells and on the development of Friend leukemia.

Abstract: Hematological effects of tilorone, an interferon inducer, on the hematopoietic cell system of normal CBA/Ca mice and on the development of Friend virus (FV-P)-induced polycythemia in DBA/2 mice were studied In normal mice 80 mg/kg IP had a marked depressive effect on pluripotent (CFU-S), granuloid committed (CFU-C), and erythroid committed (CFU-E) stem cells with regeneration between days 5 and 12 In bone marrow smears only lymphopenia was detected Treatment of mice before FV-P infection caused a slight retardation in the development of the splenomegaly and the transformation of bone marrow cells to Ep independence Repeated treatment after FV-P infection also reduced the increase in spleen weight and the development of reticulocytosis, but the Ep independence of bone marrow and spleen cells was not influenced In vitro exposure of normal cells and cells from FV-P-infected animals to the drug showed the same sensitivity of colony growth in normal as well as in Ep-independent CFU-E The action of the drug on Friend leukemia is at least in part considered a toxic effect on the hematopoietic stem cell system

Effects of ribavirin on the development of the Friend leukemia.

Abstract: Ribavirin (300 and 250 mg/kg i.p., respectively) had a toxic effect on hemopoietic stem cells in normal mice CFU-S, CFU-C, and especially CFU-E were reduced after a single treatment. The drug was further studied in mice infected with the polycythemia-inducing strain of the Friend virus (FV-P). In these mice a specific erythropoietin-independent CFU-E population (CFU-EI) replaces the normal erythropoiesis and can be considered a tumor cell population. With the in vitro technique for CFU-E, CFU-EI can easily be quantified and used as a sensitive marker for the development of the disease. Repeated doses of ribavirin reduced the increase of spleen weight after FV-P infection and the progressive transformation of normal CFU-E into CFU-EI was delayed. The further development of the disease remained unaltered. In vitro CFU-E and CFU-EI were inhibited at the same concentrations when the drug was added to the culture medium. In mice pretreated with multiple doses of hydroxyurea, ribavirin delayed the recurrence of Friend leukemia as seen from the spleen weight increase, but the CFU-E population was predominantly Ep-independent. It is concluded that the effects of the drug were due to its cytotoxicity rather than to a specific antiviral effect.

Effect of serum from mice with dormant Friend leukemia viral infections on synthesis and modulation of erythroleukemia cell surface gp70.

Abstract: Serum of mice with dormant Friend virus infections modulates the expression of cell surface antigens on Friend virus-transformed cells (FLC-745 cells). By radioimmunoassay, the modulated antigen was identified as virion gp70 of Friend leukemia virus. After two days of culture in medium containing 5% serum from mice with dormant Friend virus infections, the modulated cells expressed about 50% less surface gp70 than non-modulated cells cultured in 5% normal mouse serum. After 9 days in culture, the modulated cells expressed no surface gp70; however, these cells contained the same amount of internal gp70 as nonmodulated cells, indicating that gp70 was synthesized during the modulation period. Both modulated and nonmodulated cells grew equally well during the 9 days of culture. These results indicate that the effects of modulation of Friend virus-coded cell surface antigens are restricted to the cell surface.

Specific inducibility of globin mRNA in Friend leukemia cells in low serum concentration.

Abstract: Friend leukemia cells were adapted to grow in a medium containing 0.5% serum by gradually decreasing concentration of the serum from 15%. Upon treatment of the cells with dimethyl sulfoxide, appearance of benzidine-positive cells was suppressed in the cells cultivated in a 0.5% serum medium, whereas globin mRNA sequences, as determined by hybridization of cytoplasmic RNA with globin cDNA, increased to the same order as in the cells grown in a medium containing 15% serum. A small but significant amount of globin was synthesized in cells treated with dimethyl sulfoxide in 0.5% serum medium, as determined by dodecyl sulfate-polyacrylamide gel electrophoresis of 3H-labeled cellular proteins.

Isozyme patterns of pyruvate kinase and differentiation of friend leukemia cells

Abstract: The isozyme patterns of glycolytic enzymes of Friend leukemia cells (FLC) were compared with those of erythrocytes and erythroblasts. Erythrocyte-specific R types of pyruvate kinase (PK) were clearly observed in phenylhydrazine-induced mouse erythroblast, and much less amount of them was also observed in Friend leukemia cells. When FLC were induced to differentiate by hexamethylene-bisacetamide (HMBA), the R types were slightly reduced. When the induction of differentiation was inhibited by 12-O-tetradecanoylphorbol 13-acetate (TPA), the R types and M2-R hybrids rather increased. These results are reverse of those obtained when hemoglobin production is used as a marker of differentiation. Isozyme patterns of lactic dehydrogenase and aldolase did not change during differentiation of FLC induced by HMBA, and were the same as those of mouse erythroblasts and erythrocytes.