phosphorus-radioisotopes and Leukemia--Promyelocytic--Acute

The vav proto-oncogene product (p95vav) is specifically expressed in cells of the hematopoietic system, contains one Src homology 2 and two Src homology 3 domains, and is a substrate for receptor and non-receptor tyrosine kinases. Immunoblotting experiments using an anti-phosphotyrosine monoclonal antibody showed that interferon alpha (IFN alpha) induces rapid tyrosine phosphorylation of p95vav after binding to its cell surface receptor in the U-266 human myeloma cell line. The IFN alpha-induced tyrosine phosphorylation of p95vav was time- and dose-dependent, confirming the specificity of the process. IFN alpha-dependent tyrosine phosphorylation of p95vav was also observed in other hematopoietic cell lines of B-cell origin (Daudi), T-cell origin (MOLT-4), and promyelocytic origin (HL-60). Immunoprecipitation experiments performed with 32P-labeled U-266 cells and phosphoaminoacid analysis of the bands corresponding to p95vav showed that p95vav is phosphorylated on serine residues prior to IFN alpha stimulation of the cells. After IFN alpha stimulation significant amounts of phosphorylation of p95vav on tyrosine residues were detectable. Tyrosine phosphorylation of p95vav in U-266 and HL-60 cells was also induced by two other Type I IFNs, IFN beta and IFN omega. Altogether these data suggest that the vav proto-oncogene product is a substrate for a Type I IFN-regulated tyrosine kinase(s) and may be involved in the signal transduction pathway of Type I IFNs in hematopoietic cells.

Topics: Burkitt Lymphoma; Cell Cycle Proteins; Cell Line; Hematopoiesis; Humans; Interferon Type I; Interferon-beta; Leukemia-Lymphoma, Adult T-Cell; Leukemia, Promyelocytic, Acute; Multiple Myeloma; Phosphorus Radioisotopes; Phosphotyrosine; Proto-Oncogene Mas; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-vav; Proto-Oncogenes; Recombinant Proteins; Tumor Cells, Cultured; Tyrosine

Topics: Adenosine Diphosphate Ribose; Cell Line; Cell Membrane; Cholera Toxin; GTP Phosphohydrolases; GTP-Binding Proteins; Guanosine Triphosphate; Humans; Hydrolysis; Indicators and Reagents; Kinetics; Leukemia, Promyelocytic, Acute; Macromolecular Substances; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Phosphorus Radioisotopes; Radioisotope Dilution Technique; Receptors, Cell Surface; Tumor Cells, Cultured; Virulence Factors, Bordetella

gamma-Interferon (IFN-gamma) is a 17-kDa broad-spectrum cytokine which exerts its effects on a variety of target cells through its interaction with the IFN-gamma receptor. Although physicochemical studies of Escherichia coli-derived IFN-gamma, as well as its crystal structure, demonstrate that it is a homodimer in solution (M(r) 34,000), previous radiation inactivation studies yielded a functional size for IFN-gamma of 63-73 kDa in an antiviral assay. To understand the relationship between the solution form of IFN-gamma and the moiety that actually binds to the cellular receptor and activates cells, we examined irradiated nonradioactive and 32P-labeled IFN-gamma for its migration in SDS/polyacrylamide gels (to determine its physical integrity), its binding to cells, its reactivity in an ELISA, and its antiviral activity. The functional size of IFN-gamma differed in the assays, being 22 +/- 2 kDa for the physical destruction of IFN-gamma, 56 +/- 2 kDa for the cellular binding assay, 45-50 kDa for reactivity in the ELISA, and 72 +/- 6 kDa for antiviral activity. The results from the binding assays constitute direct evidence that IFN-gamma binds to its cellular receptor as a dimer. However, for antiviral activity, the functional mass is equivalent to a tetramer. This is consistent with models involving ligand-induced receptor dimerization, whereby two dimers acting in concert (equivalent to the target size of a tetramer) are required to activate cells in the antiviral assay.

Topics: Adenosine Triphosphate; Cell Line; Electrophoresis, Polyacrylamide Gel; Encephalomyocarditis virus; Enzyme-Linked Immunosorbent Assay; Escherichia coli; Humans; Interferon gamma Receptor; Interferon-gamma; Leukemia, Promyelocytic, Acute; Macromolecular Substances; Phosphorus Radioisotopes; Receptors, Interferon; Recombinant Proteins; Tumor Cells, Cultured; Vesicular stomatitis Indiana virus

When human peripheral blood granulocytes were metabolically labeled at 37 degrees C with [32P]orthophosphate, inorganic polyphosphates became preferentially radiolabeled. Incorporation of radiolabel into the polymer appeared to be ATP-independent. [32P]Polyphosphate was identified by its (i) characteristic lability to acid hydrolysis, (ii) insolubility in barium acetate (pH 4.5), (iii) conversion to [32P]trimetaphosphate, (iv) hydrolysis to [32P]orthophosphate by an exopolyphosphate (Saccharomyces cerevisiae scPPX1), and (v) conversion to a "phosphate ladder" which co-migrated on a polyacrylamide gel with a synthetic phosphate ladder. Also, indirect evidence suggested that the [32P]polyphosphate was strongly, noncovalently associated with another unknown molecule. Particulate fractions (13,000 x g) from lysates of human granulocytes, skin fibroblasts, HL-60 and SK-N-SH cells, all demonstrated radiolabeling of polyphosphate when incubated at 37 degrees C with [32P]orthophosphate.

Topics: Acid Anhydride Hydrolases; Autoradiography; Calcium; Cell Line; Fibroblasts; Granulocytes; Humans; Kinetics; Leukemia, Promyelocytic, Acute; Phosphates; Phosphorus Radioisotopes; Polyphosphates; Saccharomyces cerevisiae; Skin; Tumor Cells, Cultured

One major substrate protein was phosphorylated with [gamma-32P]GTP in membranes of human leukemia (HL-60) cells. The phosphoprotein comigrated with beta-subunits of heterotrimeric GTP-binding proteins (G proteins) in different gel systems. Upon solubilization of the phosphorylated membranes, the phosphoprotein could be immunoprecipitated by a G protein beta-subunit-specific antiserum. The beta-subunit phosphorylation was transient and was found to be specific for GTP and its analog, guanosine 5'-O-(gamma-thio)triphosphate. When phosphorylated membranes were incubated with various nucleotides, the bound phosphate was specifically removed by GDP, suggesting that the phosphate can be retransferred onto GDP. Divalent cations, preferentially Mg2+ and Mn2+, were required for both phosphorylation and dephosphorylation. The phosphorylation was stable against treatment with NaOH but sensitive to treatment with heat, HCl, and hydroxylamine. Moreover, treatment of the membranes with the histidine-modifying agent, diethyl pyrocarbonate, resulted in a loss in phosphate incorporation. The data suggest that G protein beta-subunits are involved in a guanine nucleotide-specific enzymatic activity transferring the gamma-phosphate from GTP to GDP, presumably at G protein alpha-subunits, via a phosphohistidine intermediate.

Topics: Biological Transport; Cell Membrane; Diethyl Pyrocarbonate; Electrophoresis, Polyacrylamide Gel; GTP-Binding Proteins; Guanine Nucleotides; Guanosine 5'-O-(3-Thiotriphosphate); Guanosine Triphosphate; Histidine; Humans; Hydroxylamine; Hydroxylamines; Kinetics; Leukemia, Promyelocytic, Acute; Macromolecular Substances; Magnesium; Manganese; Membrane Proteins; Molecular Weight; Phosphorus Radioisotopes; Phosphorylation; Tumor Cells, Cultured

Resistance to amsacrine in HL-60/AMSA is 50-100 fold compared to the parental HL-60/S cells. Synthesis and phosphorylation of topoisomerase II (TOPO II) were 2-3 fold lower in HL-60/AMSA compared to HL-60/S cells metabolically labelled with [32P]-orthophosphoric acid or [35S]-L-methionine. Incubating cells in radiolabel-free media following metabolic labelling for 4 hr revealed: (a) dephosphorylation of topoisomerase II at 4 hr was 70% and 20% in HL-60/S and HL-60/AMSA cells, respectively; and (b) degradation of topoisomerase II at 4 hr was 40% and 10% in HL-60/S and HL-60/AMSA cells, respectively, while at 8 hr degradation was 80% and 50% in HL-60/S and HL-60/AMSA cells, respectively. The magnitude of topoisomerase II band depletion in immunoprecipitates of amsacrine-treated cells labelled with [35S]-L-methionine or [32P]-orthophosphoric acid, correlated with the differential amsacrine sensitivity of HL-60/S and HL-60/AMSA cells, suggesting that the amount of newly synthesized and phosphorylated topoisomerase II may be contributing to amsacrine resistance. Thus, the attenuated synthesis and phosphorylation of TOPO II in HL-60/AMSA may contribute to the resistance of these cells to amsacrine.

Topics: Amsacrine; Autoradiography; DNA Topoisomerases, Type II; Drug Resistance; Electrophoresis, Polyacrylamide Gel; Humans; Isoenzymes; Kinetics; Leukemia, Promyelocytic, Acute; Methionine; Molecular Weight; Phosphates; Phosphorus Radioisotopes; Phosphorylation; Sulfur Radioisotopes; Tumor Cells, Cultured

Using P1 nuclease enhanced 32P postlabeling, we investigated DNA adduct formation in HL-60 promyelocytic leukemia cells treated with the benzene metabolites hydroquinone, catechol, and 1,2,4-benzenetriol. Comparison of the slopes of the dose-response curves showed that hydroquinone was 7-9 times more effective than 1,2,4,-benzenetriol and catechol at inducing DNA adducts. Comparison of hydroquinone with catechol showed a good correlation between adduct formation and cytotoxicity. Similar comparisons of hydroquinone and 1,2,4,-benzenetriol suggest that cellular processes in addition to DNA adduct formation contributed to cytotoxicity. In cells treated with the combination of hydroquinone and either catechol or 1,2,4,-benzenetriol, DNA adduct formation was 3-6 times greater than the sum of adduct formation produced by single-agent treatments. Treatment with hydroquinone and 1,2,4,-benzenetriol produced DNA adducts not detected after treatment with either metabolite alone. The synergistic interaction of benzene metabolites in the production of DNA adducts may play an important role in the genotoxic effects of benzene in vivo.

Topics: Autoradiography; Benzene; Benzoquinones; Catechols; Cell Line; Cell Survival; DNA, Neoplasm; Humans; Hydroquinones; Kinetics; Leukemia, Promyelocytic, Acute; Phosphorus Radioisotopes; Radioisotope Dilution Technique

Synthesis and degradation of glycerophospholipids in HL-60 cells and retinoic acid (RA)-treated HL-60 cells were examined. The synthesis of each subclass of ethanolamine-containing glycerophospholipids was extremely suppressed in RA-treated HL-60 cells, while that of other glycerophospholipids was not seriously affected. A pulse-chase experiment revealed that about 88% of 1,2-diacyl and 28% of 1-alkenyl-2-acyl glycerophosphoethanolamine were degraded during 4 days in RA-treated HL-60 cells. These characteristics of metabolism observed in RA-treated HL-60 cells might be responsible for the change of subclass composition of ethanolamine-containing glycerophospholipids in HL-60 cells during differentiation to granulocytes.

Topics: Cell Differentiation; Cell Line; Choline; Ethanolamine; Ethanolamines; Humans; Kinetics; Leukemia, Promyelocytic, Acute; Phosphates; Phosphatidylethanolamines; Phospholipids; Phosphorus Radioisotopes; Tretinoin; Tritium

rap1/Krev-1 is a p21ras-related GTP-binding protein that has been implicated in the reversion of the ras-transformed cell phenotype. We have identified a GTPase-activating protein (GAP) specific for rap in plasma membranes isolated from differentiated HL60 cells. The rap GAP activity remained quantitatively associated with the membrane following washes with buffered 1 M LiCl containing 20 mM EDTA but was solubilized with the detergents Nonidet P-40 and deoxycholate. On the basis of size-exclusion chromatography, the membrane-associated rap GAP (rap GAPm) appeared distinct from the rap GAP detected in the cytosolic fraction from HL60 cells. The molecular sizes of the membrane and cytosolic forms were estimated to be 36 and 54 A, respectively. rap GAPm was solubilized and purified to near homogeneity by successive column chromatographies in the presence of detergent. The rap GAPm activity corresponded to a single polypeptide that migrated with a molecular mass of approximately 88 kDa on SDS/polyacrylamide gels. The purified rap GAPm was inactive toward the GTP-bound forms of p21ras, rho, G25K, and rac-1 and did not stimulate dissociation of guanine nucleotide from rap.

Topics: Amino Acid Sequence; Antibodies; Cell Line; Cell Membrane; Chromatography; Chromatography, Gel; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Durapatite; Electrophoresis, Polyacrylamide Gel; GTP-Binding Proteins; GTPase-Activating Proteins; Guanosine Triphosphate; Humans; Hydroxyapatites; Kinetics; Leukemia, Promyelocytic, Acute; Molecular Sequence Data; Molecular Weight; Peptides; Phosphorus Radioisotopes; Proteins; rap GTP-Binding Proteins; ras GTPase-Activating Proteins

Recent investigations have identified a signal-transduction system involving sphingomyelin and derivatives. In this paradigm, sphingomyelin hydrolysis by a sphingomyelinase generates ceramide, which may be converted to the protein kinase C inhibitor sphingosine or to ceramide 1-phosphate. Ceramide may have second-messenger function because it induces epidermal growth factor receptor phosphorylation, presumably on Thr-669 in A-431 cells. The present studies describe a kinase that may mediate ceramide action. With a 19-amino acid epidermal growth factor receptor peptide containing Thr-669, a membrane-bound activity that phosphorylated the peptide was detected in A-431 cells. Activity was linearly related to ATP (0.3-300 microM) and peptide concentration (0.02-1 mg/ml), possessed a physiologic pH optimum (pH 7.0-7.4), and was Mg(2+)-dependent. Other cations--Ca2+, Mn2+, and Zn(2+)--were ineffective. Natural and synthetic ceramide induced time- and concentration-dependent enhancement of kinase activity. Ceramide (0.5 microM) increased kinase activity 2-fold by 30 s, and activity remained elevated for at least 15 min. As little as 0.001 microM ceramide was effective, and 1 microM ceramide induced maximal phosphorylation. Sphingosine was similarly effective. Because tumor necrosis factor (TNF) alpha rapidly induces sphingomyelin hydrolysis to ceramide during monocytic differentiation of HL-60 cells, its effects on kinase activity were assessed. Kinase activity was increased 1.5-fold at 5 min and 2-fold at 2 hr in membranes derived from TNF-stimulated cells. The effective concentration range was 3 pM-30 nM TNF. Exogenous ceramide induced a similar effect. In sum, these studies demonstrate the existence of an unusual Mg(2+)-dependent ceramide-activated protein kinase that may mediate some aspects of TNF-alpha function.

Topics: Amino Acid Sequence; Carcinoma, Squamous Cell; Cell Line; Cell Membrane; Ceramides; ErbB Receptors; Humans; Kinetics; Leukemia, Promyelocytic, Acute; Magnesium; Molecular Sequence Data; Peptides; Phosphates; Phosphopeptides; Phosphorus Radioisotopes; Protein Kinases; Sphingosine; Tumor Necrosis Factor-alpha

We have examined DNA adduct formation and cytotoxicity in HL-60 cells treated with either hydroquinone (HQ) or p-benzoquinone (p-BQ). Treatment of HL-60 cells with either HQ or p-BQ produced the same DNA adduct. The DNA adduct level varied from 0.05 to 10 adducts per 10(7) nucleotides as a function of treatment time and concentration for both compounds. To achieve the same DNA adduct level required higher concentrations and longer treatment times with HQ compared to p-BQ. p-BQ was also more cytotoxic to HL-60 cells than HQ. Reaction of calf thymus DNA with a p-BQ/HQ mixture produced five adducts as detected by 32P-postlabeling. Two isomers of (hydroxy)-1,N2-benzetheno-2'- deoxyguanosine-3'-phosphate were isolated from the reaction of 2'-deoxyguanosine-3'-phosphate with a p-BQ/HQ mixture and one of the isomers was identified as adduct no. 1 of the DNA reaction. The DNA adduct formed in HL-60 cells treated with HQ or p-BQ did not correspond to any of the principal adducts formed in DNA reacted with p-BQ/HQ. This result suggests that cellular mechanisms modify DNA adduct formation by HQ and p-BQ.

Topics: Benzoquinones; Cell Survival; DNA; Humans; Hydroquinones; Leukemia, Promyelocytic, Acute; Phosphorus Radioisotopes; Tumor Cells, Cultured

Topics: Cell Line; Deoxyadenine Nucleotides; Dideoxynucleotides; DNA Damage; DNA Repair; DNA Replication; DNA, Neoplasm; Humans; Kinetics; Leukemia, Promyelocytic, Acute; Phosphorus Radioisotopes; Ultraviolet Rays

Prior studies demonstrated that conversion of sphingomyelin to ceramide via sphingomyelinase action resulted in the generation of free sphingoid bases and inactivation of protein kinase C in human leukemia (HL-60) cells (Kolesnick, R. N. (1989) J. Biol. Chem. 264, 7617-7623). The present studies define the novel phospholipid ceramide 1-phosphate in these cells and present evidence for formation of this compound by preferential utilization of ceramide derived from spingomyelin. A ceramide 1-phosphate standard, prepared enzymatically via diacylglycerol kinase, was utilized for localization. In cells labeled to equilibrium with 32Pi to label the head group of the molecule, the basal ceramide 1-phosphate level was 30 +/- 2 pmol/10(6) cells. Generation of ceramide via the use of exogenous sphingomyelinase resulted in time- and concentration-dependent formation of ceramide 1-phosphate. As little as 3.8 x 10(-5) units/ml was effective and a 3-fold increase was observed with a maximal concentration of 3.8 x 10(-2) units/ml; ED50 approximately 2 x 10(-4) units/ml. This effect was observed by 5 min and maximal at 30 min. Similarly, in cells labeled with [3H]serine to probe the sphingoid base backbone, the basal level of ceramide 1-phosphate was 39 +/- 5 pmol/10(6) and increased 2.5-fold with sphingomyelinase; ED 50 approximately 5 x 10(-5) units/ml. To determine the source of the phosphate moiety, studies were performed with cells short term labeled with 32Pi and resuspended in medium without radiolabel. Under these conditions, sphingomyelin was virtually unlabeled. Nevertheless, sphingomyelin (3.8 x 10(-2) units/ml) induced a 12-fold increase in radiolabel incorporation, suggesting ceramide 1-phosphate formation occurred via ceramide phosphorylation. This event appeared specific for ceramide derived from sphingomyelin since ceramide from glycosphingolipids was not converted to ceramide 1-phosphate. In sum, these studies demonstrate the novel phospholipid ceramide 1-phosphate in HL-60 cells and suggest the possibility that a path exists from sphingomyelin to ceramide 1-phosphate via the phosphorylation of ceramide.

Topics: Autoradiography; Cell Line; Ceramides; Glycoside Hydrolases; Humans; Kinetics; Leukemia, Promyelocytic, Acute; Phosphates; Phosphorus Radioisotopes; Sphingomyelin Phosphodiesterase; Sphingomyelins; Tumor Cells, Cultured