Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calmodulin (Cam) was isolated from normal and from transformed human lymphocytes by affinity chromatography on CAPP-Sepharose 4B, followed by chromatofocusing. In the presence of Ca2+, lymphocyte Cam migrated as a single protein on 2-DE, and was located on the same position as Cam extracted from dog brain and rat testis; its MW was 17,500, with a pI of 3.9. In the presence of Ca2+, lymphocyte Cam stimulated activator-depleted dog brain phosphodiesterase; this effect was inhibited by trifluoperazine (TFP) or by EGTA. By the RIA technique, the EGTA-soluble Cam content of resting lymphocytes constituted 0.58% of the total protein; the total Cam was comparable to the content of other major proteins in lymphocytes, such as actin, tubulin, and intermediate filament protein. The amount of Cam per cell and the rate of incorporation of L-[35S]methionine into Cam increased after mitogen-induced transformation. Immunofluorescence labeling of normal, mitogen-transformed, and EBV-genome-positive lymphocytes with affinity-purified anti-Cam antibodies showed bright fluorescence in the region of the Golgi apparatus, as well as diffuse cytoplasmic but scant nuclear staining. Similar patterns were observed in T suppressor, T helper, and B cells. Normal lymphocytes cultured in the presence of 2 X 10(-5) M TFP remained viable, but failed to undergo blastogenic transformation after stimulation with allogeneic cells, concanavalin A (Con A), or pokeweed mitogen (PWM). The same concentration of TFP inhibited the replication of EBV-genome-positive and of leukemia cells. Exposure of natural killer cells or allospecific killer cells to this concentration of TFP inhibited the effector phase of killing in a dose-dependent manner. In the presence of lower concentrations of TFP (0.25-1.0 X 10(-5) M) strong MLC responses were inhibited, while weak reactions were markedly amplified. A similar effect was not observed in lymphocytes stimulated into blastogenesis by lectins, suggesting that different Cam-dependent secondary messenger(s) may be involved in the blastogenic responses evoked by alloantigenic determinants. The amplification of weak MLC responses by 0.25-1.0 X 10(-5) M TFP constitutes the first biological illustration of the capacity of a Cam-binding agent to enhance as well as to inhibit cellular activation. The paradoxical effect may have been a consequence of a shift in the relative concentrations of the four known molecular Cam X Ca2+ conformers. The results are also consistent with the suggested capacity of Cam X Ca2+ conformers to activate different enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The role of calmodulin in the regulation of human lymphocyte activation. 632 21

The calcium content of pleiotropic drug-resistant tumor cells was estimated and compared with that of the parent tumor lines. P388 leukemia cells resistant to vincristine and Adriamycin contained more calcium (1.5- to 1.8-fold) in the cells and on the cell surface than the parent P388 cells. Similar results were obtained with human K562 myelogenous leukemia cells resistant to vincristine and also with Chinese hamster ovary cells resistant to colchicine. However, the calcium content of P388 cells resistant to 5-fluorouracil was almost the same as that of the parent P388 cells. The calmodulin content of pleiotropic resistant tumor lines and a 5-fluorouracil-resistant tumor line was almost the same as that of the corresponding parent lines. The isolated plasma membrane of K562 cells resistant to vincristine contained approximately 1.5-fold higher calcium than the parent cells. These results indicate that the higher cellular calcium content might be a characteristic phenotype of pleiotropic resistant tumor lines.
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PMID:High calcium content of pleiotropic drug-resistant P388 and K562 leukemia and Chinese hamster ovary cells. 659 16

Clomipramine, which is used as antidepressant and possesses calmodulin inhibitory activity, circumvented partly the vincristine resistance in vivo. Although vincristine alone at 30-200 micrograms/kg did not confer a significant therapeutic effect in vincristine resistant P388 leukemia (P388/VCR)-bearing mice, clomipramine at doses of 20 to 50 mg/kg administered daily for 10 d with vincristine enhanced the chemotherapeutic effect of vincristine in P388/VCR-bearing mice. Approximately a 30% increase in life span occurred. Although the circumvention of vincristine resistance was not achieved perfectly, it could be speculated that more than 98-99% of vincristine resistant tumor cells which could not be killed by vincristine alone could be killed by this approach.
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PMID:Potentiation of chemotherapeutic effect of vincristine in vincristine resistant tumor bearing mice by calmodulin inhibitor clomipramine. 686 39

Some calcium antagonists and calmodulin inhibitors enhance the intracellular levels of vincristine and Adriamycin in vincristine- and Adriamycin-resistant P388 leukemia cells by inhibiting their outward transport. The high intracellular drug accumulation was directly related to the enhancement of the cytotoxicity of the antitumor agents, and the vincristine and Adriamycin resistance in these cells was circumvented.
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PMID:Increased accumulation of vincristine and adriamycin in drug-resistant P388 tumor cells following incubation with calcium antagonists and calmodulin inhibitors. 712 7

Cultured cells from patients inheriting the rare cancer-prone and radiotherapy-sensitive disorder ataxia-telangiectasia (A-T) exhibit anomalies in cell cycle control and protein kinase C (PKC)-mediated upregulation of p53 protein following exposure to ionizing radiation. It remains unclear, however, as to whether this irregularity in a p53-dependent signal transduction pathway controlling the G1/S checkpoint is causally linked to the most consistent molecular hallmark of A-T-namely, marked attenuation in the inhibition of replicative DNA synthesis at early times (< or = 2 h) after irradiation [radioresistant DNA synthesis (RDS)]. We report here that treatment of normal human fibroblast strains with inhibitors of calmodulin (CaM) (i.e. W7 and W13) and CaM-dependent protein kinases II and IV (i.e. KN62) prior to radiation exposure elicits an 'A-T-like' RDS phenotype, whereas treatment with PKC inhibitors (e.g. staurosporine) does not produce this response. Moreover, at 1 h post-gamma irradiation A-T fibroblasts undergo normal induction of p53 protein while exhibiting the RDS trait. At later times (e.g. 4 h) following irradiation, however, these A-T cells contain abnormally low levels of p53 protein, as do their lymphoblastoid cell line counterparts during the entire post-gamma ray incubation period. On the other hand, human cells which either lack the p53 gene completely (i.e. HL60 leukemia cells) or harbor a germline mutation in the gene (i.e. Li-Fraumeni syndrome cells) shut down their DNA replication machinery normally upon sustaining radiation damage. We thus conclude that the transitory delay in DNA synthesis routinely experienced by human cells in the face of radiation injury is mediated through a CaM-dependent regulatory cascade which involves neither PKC nor p53 protein. Accordingly, A-T cells appear to be malfunctional in at least two distinct radiation-responsive signalling pathways, one regulating the G1/S checkpoint and governed by p53 and PKC and another controlling passage through S phase and requiring CaM.
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PMID:Characterization of the signal transduction pathway mediating gamma ray-induced inhibition of DNA synthesis in human cells: indirect evidence for involvement of calmodulin but not protein kinase C nor p53. 747 84

The differential implication of protein kinase C (PKC) isozymes in antigen- or PMA-induced phospholipase D (PLD) activation was investigated in rat basophilic leukemia (RBL-2H3) cells. In [3H]oleic acid-labeled cells, both antigen (100 ng/ml) and phorbol 12-myristate 13-acetate (PMA) (100 nM) produced a specific product of PLD activation, [3H]phosphatidylbutanol (PBut) in the presence of butanol. Pretreatment of cells with a selective PKC inhibitor, Ro31-8425 (1-5 microM) inhibited PMA-stimulated PLD activity by 85%. In contrast, the antigen-stimulated PLD activity was much less sensitive to the inhibitor. RBL-2H3 cells express PKC alpha, beta, delta, epsilon and zeta isozymes and down-regulation of PKC by exposure to PMA (20 nM) for 1-2 h caused rapid decrease in PKC alpha and beta isozymes, leaving PKC delta, epsilon and zeta isozymes intact. Apparent decreases in the levels of PKC alpha and beta to about 50% were observed after adding 20 nM PMA for 1 h, when PMA-stimulated PLD activity was inhibited by up to 70%. Decrease in antigen-stimulated PLD activity was evident after 2 h PMA-treatment, when PKC alpha and beta decreased by nearly 70%. These results suggest that in the antigen-mediated PLD pathway PKC may be implicated but not play such a great role as PMA-stimulated pathway which is mediated through PKC alpha or beta. Then, we have examined the involvement of calcium/calmodulin (CaM) in PLD activation by antigen, since the antigen-stimulated PLD activation showed the absolute requirement for extracellular calcium. Preincubation of RBL-2H3 cells with a CaM antagonist W-7 (20 microM) inhibited the antigen-stimulated PLD activity by 90%, but W-5, a chlorine-deficient analogue of W-7 that only weakly interact with CaM, caused little inhibitory effect. Another non-specific CaM antagonist, trifluoperazine (TFP) also inhibited PLD activation. These results suggest that calcium/CaM may be involved in the antigen-stimulated PLD activation.
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PMID:Antigen-mediated phospholipase D activation in rat basophilic leukemia (RBL-2H3) cells: possible involvement of calcium/calmodulin. 754 73

Calmodulin plays an important role in cellular proliferation as part of a signal transduction pathway activated by phospholipase C. Drugs that block the ability of calmodulin to bind to and activate its target enzymes inhibit the growth of a wide variety of malignant cells. To identify more potent and selective inhibitors of this potential target for new drug development, we studied two recently synthesized compounds, KS-501 and KS-502, for their activity against calmodulin-sensitive enzymes and for their ability to block the growth of parental and multidrug-resistant leukemic cells. KS-501 and KS-502 inhibited the activation of a calmodulin-sensitive cyclic nucleotide phosphodiesterase. The mechanism of enzyme inhibition was through interfering with calmodulin activation rather than through a direct effect on the enzyme. KS-501 was more potent than KS-502 and was studied in greater detail. This compound inhibited the activation of calmodulin kinase I and II, but had less effect against cyclic adenosine 3',5'-monophosphate (cyclic AMP)-sensitive kinase. KS-501 was also more effective than KS-502 in inhibiting the growth of sensitive L1210 leukemic lymphocytes. Both compounds were less effective inhibitors of multidrug-resistant L1210 leukemia than of the parental line. These studies identify a new class of calmodulin inhibitor, with selectivity for calmodulin-dependent kinases over cyclic AMP-dependent protein kinase. Since the total synthesis of the KS-compounds has been accomplished, it should now be possible to develop derivatives with greater activity and selectivity.
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PMID:Effects of KS-501, KS-502 and their enantiomers on calmodulin-sensitive enzyme activity and cellular proliferation. 760 47

Nuclear factor of activated T-cells (NFAT) is a transcriptional activator that binds to the interleukin-2 promoter and is believed to be responsible for T-cell-specific interleukin-2 gene expression. Here we demonstrate using electrophoretic mobility shift assays that nuclear NFAT can be induced in the rat basophilic leukemia (RBL-2H3) mast cell line and rat bone marrow-derived mast cells upon cross-linkage of the high affinity receptor (Fc epsilon RI) for immunoglobulin E (IgE). Receptor-dependent activation of NFAT was mimicked by the combination of the protein kinase C activator phorbol myristate acetate and the calcium ionophore ionomycin. The induced binding activity was specific for the NFAT recognition motif because competition with nonradioactive NFAT oligonucleotide abolished the DNA binding activity, whereas nonradioactive oligonucleotides recognized by the transcription factors NF kappa B, glucocorticoid receptors, and TFIID did not. An oligonucleotide representing the AP-1 recognition sequence also blocked the NFAT DNA binding activity, as did a combination of anti-Fos and anti-Jun antibodies. Using electrophoretic mobility shift assays, AP-1-binding proteins were found to be induced in RBL-2H3 cells under the same conditions as was the NFAT binding activity. Together these data suggest that the NFAT complex in mast cells contains Fos and Jun proteins as does NFAT in T-cells. The appearance of nuclear NFAT binding activity was dependent in part upon calcium mobilization, as buffering the antigen-induced calcium rise with intracellular BAPTA strongly inhibited NFAT activation. Prevention of calcium influx with external EGTA also inhibited NFAT activation, indicating that release of calcium from internal stores was insufficient for sustained activation of mast cell NFAT. Cyclosporin A, a potent inhibitor of the calmodulin-dependent phosphatase calcineurin, blocked the induction of NFAT-DNA binding activity, implicating calcineurin as a key signaling enzyme in this pathway. These results suggest that NFAT is present in the mast cell line RBL-2H3 and in primary bone marrow-derived mast cells, is similar in subunit composition to the T-cell NFAT, and may play a role in calcium-dependent signal transduction in mast cells.
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PMID:Fc epsilon RI-mediated induction of nuclear factor of activated T-cells. 760 2

Whole-cell patch-clamp recordings and single-cell Ca2+ measurements were used to study the control of Ca2+ entry through the Ca2+ release-activated Ca2+ influx pathway (ICRAC) in rat basophilic leukemia cells. When intracellular inositol 1,4,5-trisphosphate (InsP3)-sensitive stores were depleted by dialyzing cells with high concentrations of InsP3, ICRAC inactivated only slightly in the absence of ATP. Inclusion of ATP accelerated inactivation 2-fold. The inactivation was increased further by the ATP analogue adenosine 5'-[gamma-thio]triphosphate, which is readily used by protein kinases, but not by 5'-adenylyl imidodiphosphate, another ATP analogue that is not used by kinases. Neither cyclic nucleotides nor inhibition of calmodulin or tyrosine kinase prevented the inactivation. Staurosporine and bisindolylmaleimide, protein kinase C inhibitors, reduced inactivation of ICRAC, whereas phorbol ester accelerated inactivation of the current. These results demonstrate that a protein kinase-mediated phosphorylation, probably through protein kinase C, inactivates ICRAC. Activation of the adenosine receptor (A3 type) in RBL cells did not evoke much Ca2+ influx or systematic activation of ICRAC. After protein kinase C was blocked, however, large ICRAC was observed in all cells and this was accompanied by large Ca2+ influx. The ability of a receptor to evoke Ca2+ entry is determined, at least in part, by protein kinase C. Antigen stimulation, which triggers secretion through a process that requires Ca2+ influx, activated ICRAC. The regulation of ICRAC by protein kinase will therefore have important consequences on cell functioning.
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PMID:Depletion-activated calcium current is inhibited by protein kinase in RBL-2H3 cells. 764 12

The study was conducted on human leukemia (K 562) cells to characterize the mechanisms implicated in the regulation of the polyamine spermidine (Spd) transport process. The antagonists of calmodulin, trifluoperazine (TFP), W-7 (N-[6-aminohexyl]-5-chloro-1-naphthelenesulfonamide), or mellitin inhibited significantly polyamine Spd uptake in these cells. The translocation of calmodulin towards plasma membrane and a concomitant decrease in its contents in cytosol were directly correlated with the time course increases similar to that of Spd uptake, indicating that calmodulin is recruited towards plasma membrane during the Spd transport process. Diminution of free intracellular calcium, (Ca2+)i, by preincubating the cells in BAPTA (bis[2-amino-5-methylphenoxyl]-ethane-N,N,N',N',-tetraacetate) buffer inhibited Spd transport significantly. Addition of lanthanum (LAN), a molecule known to inhibit Ca2+ efflux via Ca(2+)-ATPase, curtailed Spd uptake by these cells. LAN inhibited Vmax, but not the Km, of Spd uptake, indicating that the former does not directly interact with the polyamine transporter; rather it regulates the transport process, probably via its action on Ca(2+)-ATPase. Calmodulin-stimulated uptake of 45Ca2+ by inside-out vesicles of K 562 cells, a measure of Ca(2+)-ATPase activity. Furthermore, addition of LAN inhibited both basal and calmodulin-stimulated activity of Ca(2+)-ATPase. Thapsigargin (THAP), a molecule known to elevate (Ca2+)i due to its action on the endoplasmic reticulum, increased Spd transport whereas addition of LAN inhibited THAP-stimulated Spd transport activity. THAP increased free (Ca2+)i in these cells, and a pre-addition of LAN to these cells curtailed the THAP-stimulated increases of (Ca2+)i concentrations. Addition of Spd brought about elevations in (Ca2+)i contents. Caffeine also increased (Ca2+)i in these cells; however, it failed to stimulate significantly the Spd uptake process, indicating that (Ca2+)i which is involved in the regulation of polyamine transport pathways does not belong to the calcium-induced calcium-release (CICR) pool. Replacement of Ca2+ from the incubation medium (i.e., 0% Ca2+) resulted in higher uptake activity as compared to that in 100% Ca2+ medium, demonstrating that in 100% Ca2+ medium the calcium efflux process is quickly compensated by calcium refilling/influx from the extracellular medium, while in 0% Ca2+ medium there is perpetual efflux of (Ca2+)i which contributes to higher Spd uptake process. The results of this study suggest that an increase in free (Ca2+)i and its release from the cells via Ca(2+)-ATPase, and concomitant activation of calmodulin, which controls Ca(2+)-pump activity, are involved in the regulation of the Spd uptake process in human leukemia cells.
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PMID:Polyamine transport regulation by calcium and calmodulin: role of Ca(2+)-ATPase. 825 60


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