Glycosphingolipid patterns in human promyelocytic HL-60 leukemia cells susceptible or resistant to differentiation induction by phorbol 12-myristate 13-acetate (original) (raw)
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Molecular Pharmacology, 2002
Previous studies have emphasized the role of glucosylceramide (Glu-Cer) synthase in multidrug resistance (MDR) regulation. However, the mechanism by which the inhibition of this enzyme results in increased drug retention and cytotoxicity remains unclear. In this study, we investigated the respective role of ceramide (Cer) accumulation and Glu-Cer derivatives depletion in MDR reversal effect of 1-phenyl-2-decanoylamino-3-morpholino-1-propanolol (PDMP), a Glu-Cer synthase inhibitor. We show here that treatment with PDMP resulted in increased rhodamine 123 (Rh123) retention and potent chemosensitization of P-glycoprotein (P-gp)-expressing cells, including KG1a cells, KG1a/200 cells, K562/138 cells, and K562/mdr-1 cells. Metabolic studies revealed that PDMP induced not only timedependent Cer accumulation but also reduction of all glycosy-lated forms of Cer, including Glu-Cer, lactosylceramide (Lac-Cer), monosialo ganglioside (GM3) and disialo ganglioside (GD3). The influence of these metabolites on P-gp function was investigated by measuring Rh123 retention in PDMP-treated cells. P-gp function was found to be stimulated only by the addition of gangliosides in all resistant cell lines, whereas Glu-Cer, Lac-Cer, and Cer had no effect. Moreover, in KG1a/200 cells, GD3 and, to a lesser extent, GM3 were found to phosphorylate P-gp on serine residues. Altogether, these results suggest that, at least in leukemic cells, gangliosides depletion accounts for PDMP-mediated MDR reversal effect, and that gangliosides are important P-gp regulators perhaps through their capacity to modulate P-gp phosphorylation.
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There is a continuous demand to improve monoclonal antibody production for medication supply and medical cost reduction. For over 20 years, recombinant Chinese hamster ovary cells have been used as a host in monoclonal antibody production due to robustness, high productivity and ability to produce proteins with ideal glycans. Chemical compounds, such as dimethyl sulfoxide, lithium chloride, and butyric acid, have been shown to improve monoclonal antibody production in mammalian cell cultures. In this study, we aimed to discover new chemical compounds that can improve cell-specific antibody production in recombinant Chinese hamster ovary cells. Out of the 23,227 chemicals screened in this study, 4-(2,5-dimethyl-1H-pyrrol-1-yl)-N-(2,5-dioxopyrrolidin-1-yl) benzamide was found to increase monoclonal antibody production. The compound suppressed cell growth and increased both cell-specific glucose uptake rate and the amount of intracellular adenosine triphosphate during monoclonal antibo...
Inhibition of pyrimidine metabolism in myeloid leukemia cells by triazole and pyrazole nucleosides
Biochemical Pharmacology, 1990
Two triazole nucleosides, 1 (3-gD-ribofuranosyl-1,2,4-triazole-5-carboxamide) and 2 (2-P-D,ribofuranosyl-1,2,3-triazole-4,5_dicarboxamide), and a pyrazole nucleoside, 3 (1+-D-ribofuranosylpyrazole-3,4_dicarboxamide), were found to inhibit pyrimidine nucleotide biosynthesis in the human myeloid leukemia cell line, K562. Cells treated with these inhibitors released orotate in quantities of 8-35 nmol/105 cells/day. Treatment with these compounds caused the K562 cells to accumulate in the S phase of the cell cycle and induced the cells to synthesize hemoglobin. MATERIALS AND METHODS Cell culture. A myeloid cell line, K562, was obtained from the American Type Culture Collection. The cells were cultured in RPM1 1640 medium supplemented with 10% fetal bovine serum and 2 mM glutamine at 37" in an atmosphere of 5% CO2 in air. Cell densities were maintained between 0.5 x lo5 and 15 x lo5 cells per mL. Cell numbers were determined with a Coulter Counter model ZB. Cell viabilities were determined with trypan blue stain. In our hands, the doubling time of the K562 cells was 28 2 3 hr. Synthesis of compounds. All of the nucleosides (Figs 1 and 2) were synthesized at the Nucleic Acid Research Institute by published procedures [4-lo]. Measurement of nucleosides and nucleotides. High pressure liquid chromatography was used to quantitate the nucleotides and nucleosides in cell and medium fractions following incubation with the compounds. Following incubation of K562 cells in culture
Biochemical Pharmacology, 1991
The present studies have examined the effects of hexamethylene bisacetamide (HMBA) on the human U-937 monocytic cell line. HMBA treatment was associated with: (1) decreases in U-937 cell proliferation, (2) increases in nonspecific esterase activity and cell surface antigen expression consistent with monocytic differentiation, (3) decreases in c-myc gene expression, and (4) induction of tumor necrosis factor (TNF) transcripts. Treatment of U-937 cells with HMBA was also associated with increases in phospholipase A2 activity and increases in the release of arachidonic acid and its metabolites. Dexamethasone, an agent previously shown to inhibit monocytic differentiation, had no detectable effect on the down-regulation of c-rnyc, but blocked the induction of TNF expression. Taken together, the results demonstrate that HMBA induces monocytic differentiation of U-937 cells and that this effect is sensitive, in part, to dexamethasone.
Spectrophotometric Studies of Some Novel Derivatives of Pyridinium Chloride
Croatica Chemica Acta, 1999
The UV-Vis and IR characteristics of five novel aralkyl derivatives of pyridinium chloride, found to be reversible inhibitors of acetylcholinesterase, are reported. The dissociation constants of the individual keto and oxime functional groups were determined spectrophotometrically and discussed in terms of the known pK values of compounds with similar structures. The three examined derivatives of the phenacylpyridinium type contain in solution a considerable proportion of the enol form while their next higher homologues are present predominately in their keto forms. AM1 molecular-orbital calculations show that the much higher acidity of a-CH 2 group of benzoylethylpyridinium type compounds is a consequence of an anomeric effect. CROATICA CHEMICA ACTA CCACAA 72 (1) 123¿133 (1999)
Cytotoxic activity of the selected pyridinium salts against murine leukemia L1210
Pharmacological Reports, 2007
The objective of this work was to evaluate the relationship between chemical reactivity of 3-substituted pyridinium salts and their cytotoxic properties against murine leukemia L1210. Chemical reactivity of pyridinium salts towards NADH oxidation following one-step hydride transfer depends strongly on their redox properties. The investigated reaction may reflect the ability of the salts to deplete NADH level in cells and to affect their metabolic functions. On the other hand, the cytotoxic activity against murine leukemia cells, expressed as ED # values, varied strongly depending upon the compound used. The investigated salts showed also a diverse antileukemic effect in in vivo experiments as measured by the increase in the survival time of L1210 leukemia-bearing mice. These biological effects were correlated with equilibrium constants found for the reaction of pyridinium salts with NADH.
Apoptosis and cytolysis induced by giganteosides and hederacolchisides in HL-60 cells
Anticancer research
The viability, cytolysis and apoptosis-mediated cellular death induced by giganteosides D and E (Gig-D and Gig-E) and hederacolchisides A and A1 (Hcol-A and Hcol-A1) were analysed in HL-60 cells. The end-point metabolic (WST1) and lactate dehydrogenase (LDH) assays were used. Cell cycle analysis and apoptosis were measured by flow cytometry, DNA laddering and caspase-3 analyses. the HL-60 cell line was more sensitive to Hcol-A1 and Gig-D (IC50 3-5 microM) than to Gig-E and Hcol-A (IC50 8-13 microM; WST1 assay). This was related to LDH release. The induction of apoptosis could be detected without caspase-3 activation after 24 h of treatment. DNA fragmentation could be detected only with Gig-D. With Hcol-A1 and Gig-D, an accumulation of cells in the S-phase and an increase of cells in sub-G1 peak were observed. By the annexinV-fluorescein isothiocyanate (FITC)/7-amino-actinomycin D (AAD) assay, the majority of cells were in late apoptosis with Gig-D, and in necrosis with Hcol-A1. Hcol...
Modulation of dipyridamole action by α1acid glycoprotein
Biochemical Pharmacology, 1989
Dipyridamole potentiates the cytotoxicity of N'"-propargyl-5,8-dideazafo1ic acid (CB3717), an antifolate inhibitor of thvmidvlate svnthase. bv inhibiting both thvmidine (TdR) salvage and deoxyuridine (UdR) efflux. Dipyrihamole binds to the serum component &acid glycoprotein (GAGP) and hence the effects of a+AGP on dipyridamole-induced changes in nucleoside transport and CB3717 cytotoxicity have been investigated. Using A549 lung cancer cells in vitro, (u,AGP reduced the inhibition of nucleoside transport by dipyridamole in a concentration-dependent manner. Between 10 and 200 times the concentration of dipyridamole was needed to inhibit TdR uptake to the same degree in medium containing 1 mg/ml (u,AGP (a physiological concentration) when compared to the uptake in arAGP-free medium. Although dipyridamole inhibited UdR efflux more than TdR efflux, inhibition of UdR efflux was reduced less than the inhibition of TdR efflux in the presence of 1 mg/ml triAGP. Thus, clinically achievable levels of dipyridamole (2.5-7.5 PM), even in the presence of physiological &iAGP concentrations, caused significant inhibition of nucleoside uptake and efflux. The cytotoxicity of CB3717 was increased 2-3-fold by 3 and 10 PM dipyridamole in orAGP-free medium, whereas dipyridamole did not significantly (P 2 0.05) potentiate CB3717 cytotoxicity in the presence of 1 mg/ml arAGP. Measured free dipyridamole levels indicated that the impaired inhibition of nucleoside transport and the lack of potentiation of CB3717 cytotoxicity in the presence of trrAGP was due solely to the binding of dipyridamole to triAGP. It is concluded that ru,AGP levels will be a major determinant of the ability of dipyridamole to modulate the activity of antimetabolites in uiuo.
A Semisynthetic 5-n-Alkylresorcinol Derivative and its Effect upon Biomembrane Properties
Zeitschrift für Naturforschung C, 2007
MSAR (1-sulfate-3-myristoyl-5-pentadecylbenzene) is a semisynthetic derivative of 5-npentadecylresorcinol (C15:0). MSAR exhibits hemolytic activity against sheep erythrocytes with a EH 50 value of (35 ð 1.7) μm. At low concentrations MSAR also exhibits the ability to protect cells against their hypoosmotic lysis. This protective effect is significant as, at 0.1 μm of MSAR, the extent of osmotically induced cell lysis is reduced by approx. 20%. It was demonstrated that the 9-anthroyloxystearic acid signal was most intensively quenched by MSAR molecules, suggesting a relatively deep location of these molecules within the lipid bilayer. MSAR causes an increase of the fluorescence of the membrane potential sensitive probe. This indicates an alteration of the surface charge and a decrease of the local pH value at the membrane surface. At low bilayer content (1Ð4 mol%) this compound causes a significant increase of the phospholipid bilayer fluidity (both under and above the main phase transition temperature) of dipalmitoylphosphatidylcholine (DPPC) liposomes. At this low content MSAR slightly decreases the main phase transition temperature (T c ) value. The effects induced in the phospholipid bilayer by higher contents of MSAR molecules (5Ð10 mol%) make it impossible to determine the T c value and to evaluate changes of the membrane fluidity by using pyrene-labeled lipid. MSAR also causes a decrease of the activity of membrane-bound enzymes Ð red blood cell acetylcholinesterase (AChE) and phospholipase A 2 (PLA 2 ). MSAR decreases the AChE activity by 40% at 100 μm. The presence of MSAR in the liposomal membrane induces a complete abolishment of the lag time of the PLA 2 activity, indicating that these molecules induce the formation of packing defects in the bilayer which may result from imperfect mixing of phospholipids.
Prostaglandins, Leukotrienes and Essential Fatty Acids, 1992
We studied fatty acid changes that are likely to occur during phorbolmyristate acetate (PMA)induced differentiation of HL-60 cells. It was observed that PMA-induced differentiation is associated with increased uptake, but not synthesis, of fatty acids. Fatty acid analysis revealed that arachidonic acid (AA), 20:5 n-3 and 22:6 n-3 levels are reduced with a concomitant increase in 22:5 n-6 in the phospholipid fraction. In the FFA fraction there are increases in free AA, free 20:s n-3, 22:s n-3 and 22:6 n-3, and a fall in free 22:s n-6 in PMA-treated cells.