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)

The effects of thrombopoietin (TPO) on cell proliferation and differentiation, and the relation between these effects and the expression of c-mpl on leukemia cells were studied in seven acute myelogeneous leukemia cell lines and seven myelogeneous blast cell preparations from patients with chronic myeloproliferative disorders (CMPDs) and myelodysplastic syndrome (MDS). Among the leukemia cells, five preparations of megakaryoblastic leukemia cells from patients and one megakaryoblastic cell line, CMK 11.5, proliferated in response to TPO in vitro. CMK 11.5 and the blastic cells from one patient diagnosed with MDS with myelofibrosis differentiated with increasing expression of CD41a in response to TPO. However, TPO had no effect on the cells lacking megakaryocytic characteristics. Some patients with CMPD and MDS develop acute transformation with blasts demonstrating megakaryocytic features, and some of these cells show growth in response to TPO. Therefore, in vivo administration of TPO should be considered carefully for patients with CMPD or MDS, since TPO may induce leukemic cell proliferation.
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PMID:Thrombopoietin activates the growth of megakaryoblasts in patients with chronic myeloproliferative disorders and myelodysplastic syndrome. 1077 93

In actinomycin D (AD)-induced apoptosis, caspase-3 activation and DNA cleavage in human megakaryoblastic leukemia CMK-7 cells were greatly accelerated by tubulin and actin polymerization inhibitors [e.g., colcemid (CL) and cytochalasin D (CD), respectively], but the acceleration was not found with Taxol or phalloidin. A decrease in mitochondrial transmembrane potential, release of cytochrome c into the cytosol, and cleavage of procaspase-9 to its active form preceded the activation of caspase-3 and, moreover, all of these events began earlier and/or proceeded faster in cells treated with AD plus CL or CD than in cells treated with AD only. These results suggest that cytoskeletal disruption in the apoptotic cells promotes damage of the mitochondrial membrane, resulting in the enhanced release of cytochrome c necessary for the activation of caspase-9 that initiates the caspase cascade. On the other hand, apoptotic bodies were rapidly formed from cells treated with AD and CL, but were suppressed when treated with AD and CD. Intracellular membranes and the actin system were reorganized to surround the nuclear fragments in the AD- and CL-treated cells, but such a membrane system was not formed in the presence of CD, implying that the apoptotic bodies are formed via reorganization of intracellular membranes under regulation by actin polymerization. Thus, the cytoskeletal change in CMK-7 cells has a strong effect on the early biochemical process as well as on the later morphologic process in AD-induced apoptosis.
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PMID:Cytoskeletal disruption accelerates caspase-3 activation and alters the intracellular membrane reorganization in DNA damage-induced apoptosis. 1094 79

The rate of ara-cytosine triphosphate (ara-CTP) accumulation and its retention has been correlated with 1-beta-D-arabinofuranosylcytosine (ara-C)-mediated toxicity and clinical outcome in childhood and adult leukemia. We tested to what extent preincubation with the ribonucleotide reductase inhibitors fludarabine (F-ara-A) and hydroxyurea (HU) enhanced ara-CTP levels in two human myeloid (HL-60, CMK) and two lymphoblastic leukemia cell lines (MOLT-4, BLIN-1) and also in blasts from 28 children with acute leukemia (AML: 14, ALL: 14). Incubation experiments carried out with cell lines showed F-ara-A and HU to be equipotent in increasing ara-CTP levels. The highest increase was observed in HL-60 cells whereas preincubation had no modulatory effect in MOLT-4 cells. Accordingly, modulation of intracellular ara-CTP levels differed between the subtypes of childhood acute leukemia: whereas in T-ALL (five) preincubation with F-ara-A and HU had no effect on intracellular ara-C metabolism, increased ara-CTP levels were seen in some cases of pre-B-ALL (seven). In myelogenous blasts (12) clinically relevant enhancement of ara-C toxification was regularly obtained with both, F-ara-A (1.9-fold) and HU (1.5-fold). In conclusion, our data suggest that combinations of ara-C and ribonucleotide reductase inhibitors are apt to increase ara-CTP levels depending on the individual cell type and its sensitivity towards ara-C modulators.
Leukemia 2001 Jan
PMID:Modulation of ara-CTP levels by fludarabine and hydroxyurea in leukemic cells. 1124 2

Thrombopoietin (TPO) plays a crucial role in megakaryocyte development. TPO signalling, which is mediated by its receptor Mpl, includes Janus kinase, (JAK) signal transducer and activator of transcription (STAT) and Shc/Ras/mitogen-activated protein kinase (MAPK) pathways. The precise nature of these signalling routes has not been clarified in detail up until now. We investigated the effect of TPO on activation of cAMP-dependent protein kinase (PKA) and its involvement in MAPK signalling in human megakaryoblastic leukaemia CMK cells. For estimation of PKA activity, phosphorylation of a PKA-specific peptide substrate was assayed in CMK cell lysates. Since activation of PKA is associated with translocation of its catalytic subunit alpha (C-PKA) into the cell nucleus, Western blot analysis of nuclear fractions with an anti-C-PKA antibody was additionally performed. The activation of TPO-induced MAPK activation and the effect of the PKA inhibitor H-89 was measured using immunoblotting with a monoclonal anti-pERK antibody. TPO enhanced cAMP and induced activation of PKA in CMK cells. In addition, H-89 partly blocked TPO-induced MAPK activation in CMK cells. Our results indicate a novel TPO-triggered signalling event, activation of the cAMP/PKA pathway in human megakaryoblastic CMK cells. This signal transduction route seems to be involved in TPO-induced MAPK signaling.
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PMID:Evidence for a novel thrombopoietin signalling event: activation of protein kinase A in human megakaryoblastic CMK cells. 1150 82

Actinomycin D (AD)-induced apoptosis in CMK-7 cells is greatly accelerated by cytoskeletal poisons such as colcemid (CL) and cytochalasin D (CD). This phenomenon is important in the combination chemotherapy of cancer so that its generality was investigated. Four human leukemia and two human solid tumor cell lines were treated with combinations of one DNA-damaging agent [AD, mitomycin C (MMC), or etoposide (VP- 16)] and one cytoskeletal poison [CL, CD, or vinblastine (VBL)]. The apoptosis was monitored by assaying caspase-3 activity and the DNA cleavage ratio. The caspase-3 activation in all leukemia and HeLa S3 cell lines was, except for a few cases, 1.3-to 6.0-fold enhanced by combinations of the DNA-damaging agent with a cytoskeletal poison. The DNA cleavage ratio as well as the dead cell ratio was also 1.4-to 23.7-fold enhanced in CMK-7, U-937, HeLa S3, and Colo320 DM cell lines by the combinations of AD with CL, CD, or VBL. The combination index for caspase-3 activation by AD and CL in U-937 cells was smaller than 1 at Fa of more than 0.03. Thus, apoptosis in many tumor cell lines is synergistically enhanced by various combinations of DNA- and cytoskeleton-damaging agents.
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PMID:Synergistic enhancement of apoptosis by DNA- and cytoskeleton-damaging agents: a basis for combination chemotherapy of cancer. 1172 25

Granulysin is a newly reported cytolytic molecule and colocalizes with perforin and granzymes in the granules of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. In this study, we found that the megakaryoblastic leukemia cell line CMK, established from a patient with Down's syndrome, expressed granulysin mRNA. CMK was positive for CD13 and CD41 and negative for CD56. CMK also expressed CD2 and CD7. However, no rearrangement of the T-cell receptor beta-chain gene, an early marker of T-cell lineage, was found in CMK cells. Thus, CMK is assumed to originate from the clonal evolution at the immature cell level. The expression of granulysin in CMK cells suggests that granulysin is occasionally present in immature multilineage cells or may be characteristic of leukemic cells obtained from Down's syndrome patients. CMK has been reported to be capable of differentiating to mature megakaryocytes and produce platelets with normal function. It therefore seems to be possible that granulysin is also present in normal platelets. Unfortunately, we were not able to obtain evidence that normal platelets contain granulysin mRNA and its antigen.
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PMID:Expression of granulysin mRNA in the human megakaryoblastic leukemia cell line CMK. 1214 61

A tetrahydroxyanthrone derivative, resistomycin, was isolated from the culture broth of Streptomyces sulphureus and a similar polyphenolic dianthraquinone, hypericin, was isolated from an extract of Hypericum perforatum L. as modulators for apoptosis. Resistomycin inhibited apoptosis induced by actinomycin D (AD) with or without acceleration by colcemid (CL) in human megakaryoblastic leukemia CMK-7 cells, IC50 for inhibition against AD-induced apoptosis was about 0.5 microM and IC50 for inhibition against AD plus CL-induced apoptosis was about 1 microM. CL alone induced weak apoptosis in cells, which was enhanced by resistomycin. Hypericin did not inhibit AD-induced apoptosis and slightly enhanced CL-induced apoptosis. Emodin, corresponding to 1 of 2 anthraquinone units in hypericin, did not show any effect on this apoptotic system. AD-induced apoptosis was inhibited by the antioxidative flavonoid, luteolin (IC50 45 microM), and a protein kinase C (PKC) inhibitor, staurosporine (IC50 1.5 microM), but these compounds did not affect the CL-induced apoptosis. Hypericin and resistomycin scavenged superoxide anion radicals at the same rate as luteolin. PKC in CMK-7 cells was inhibited by hypericin and luteolin, but not significantly inhibited by resistomycin. This result suggests that the inhibition of AD-induced apoptosis by resistomycin is at least partly correlated with its antioxidative activity, and that the enhancement of CL-induced apoptosis by this compound depends upon the lack of PKC inhibitory activity. Though the mechanism is not clear, the enhancement of the CL-induced apoptosis might be hindered by PKC inhibition in the case of hypericin and luteolin.
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PMID:Effects of polyphenolic anthrone derivatives, resistomycin and hypercin, on apoptosis in human megakaryoblastic leukemia CMK-7 cell line. 1244 Jul 35

The caspase family of protease is speculated to have a crucial role in apoptosis. The effect of treatment with Idarubicin (IDA) and Medroxyprogesterone acetate (MPA), used alone or in combination, on the activation of Caspase-3 in canine Chronic Lymphatic Leukaemia (CLL) cells was investigated, in order to clarify the mechanism of chemo- and hormone-therapy mediated apoptosis. Caspase activity was determined by a quantitative fluorimetric assay. Apoptosis was monitored by propidium iodide (PI) and nucleosomes assay. Treatment of CLL cells for 24 h with MPA 5 microM did not significantly activate caspase-3 but its activity was increased almost 5-fold more with IDA 1 microM (P < 0.05) than control. Treatment of CLL cells with IDA 1 microM in equimolecular association with MPA was able to increase the activation of caspase-3 induced by IDA of the 61.2% (P < 0.05) in comparison with IDA alone. The activation of caspase-3 was confirmed evaluating apoptosis by PI and nucleosomes assay. Furthermore, both caspase-3 activation and apoptosis triggered by IDA alone or in combination with MPA were significantly inhibited by specific caspase-3 inhibitor AC-DEVD-CMK. These findings provide an explanation for IDA and MPA induced-apoptosis mechanism.
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PMID:MPA increases idarubicin-induced apoptosis in chronic lymphatic leukaemia cells via caspase-3. 1285 40

Differentiation induction is a therapeutic principle in acute promyelocytic leukemia (AML) using all- trans retinoic acid. In cell lines with properties of AML M6/M7 (K562 and CMK), differentiation towards megakaryopoietic and erythropoietic phenotypes can be induced in vitro. Transitory myeloproliferative disorder (TMD) is a self-limited disorder of newborn infants with Down syndrome, phenotypically resembling acute myeloid leukemia of megakaryoblastic lineage. Despite spontaneous disappearance of blasts from blood and bone marrow, in about 10% of the patients, overt acute megakaryoblastic leukemia (AML M7) develops up to 4 years later. Recently, mutations of the GATA1 transcription factor have been identified in the megakaryoblastic leukemia of Down syndrome. Here, we studied cells from a patient suffering from megakaryoblastic AML at the age of 2.5 years after spontaneous remission of neonatal TMD. In vitro, terminal differentiation towards a megakaryocyte-like phenotype could be induced by phorbol myristate acetate (PMA), with typical morphological features, upregulation of platelet-specific and downregulation of erythroid antigens, going along with downregulation of c-myc. Whether spontaneous resolution of TMD is a process due to terminal differentiation is still open; however, here we give evidence that in vitro differentiation can be induced even in blasts deriving from an overt AML French-American-British (FAB) M7 after TMD.
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PMID:Terminal differentiation in vitro of patient-derived post-TMD megakaryoblastic AML cells. 1291 Mar 77

The actinomycin D (AD)-induced apoptosis in human leukemia CMK-7 cell line is greatly accelerated by microtubule disruption with colcemid (CL). We studied the effect of antioxidants on this apoptosis in order to learn how the universal signal mediators, reactive oxygen species (ROS), are involved. Caspase-3 activation and DNA fragmentation were both suppressed by vitamin E (VE), t-butylhydroxyanisole, and luteolin. The ROS formation in the AD treatment was evidenced by flow cytometry, and further supported by suppression of caspase-3 activation by superoxide radical-forming enzyme inhibitors (TTFA, rotenone, and DPI). The inhibition of apoptosis by VE was completed during the initial 1-h treatment with AD, but it did not appear when VE was added with CL to washed cells after AD treatment. Luteolin, an iron chelator PDTC, and a water-soluble VE analogue, trolox, inhibited the apoptosis when added with CL after the AD treatment. Western blot analysis showed that the proteolytic cleavage of procaspase-9 and procaspase-3 were both inhibited when VE was added with AD or when luteolin was added with CL, and that the cytochrome c liberation was suppressed by both antioxidants. This result implies that the ROS are initially formed in lipophilic environments (e.g. mitochondrial membrane) and then they diffuse into an aqueous environment (i.e. cytoplasm) where they promote the apoptotic process in combination with the cytoskeletal disruption. Thus, the different antioxidants are effective to scavenge ROS for preventing the apoptosis in its different phases.
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PMID:Differential effects of vitamin E and three hydrophilic antioxidants on the actinomycin D-induced and colcemid-accelerated apoptosis in human leukemia CMK-7 cell line. 1296 51


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