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 long terminal repeat (LTR) of the human T-cell leukemia virus type I (HTLV-I) contains an imperfect repeat of 21 nucleotides which governs the response to the virus trans-activator protein tax and to cyclic AMP. In a murine thymocyte cell line defective in the catalytic subunit of protein kinase A, the response of the HTLV-I LTR to cyclic AMP is abolished and the response to tax is substantially diminished. This report shows that a factor present in nuclear extracts of wild-type cells binds to the HTLV-I 21-nucleotide sequence and that this binding activity is missing from the extracts of protein kinase A-defective cells. Treatment of nuclear extracts of protein kinase A-defective cells with the bovine protein kinase A catalytic subunit restores the binding activity, whereas treatment of wild-type nuclear extracts with a protein phosphatase destroys the binding activity. The binding factor is referred to as protein kinase A-dependent factor (PKAF). These results indicate that in murine thymocytes the response of the HTLV-I LTR to cyclic AMP depends upon the binding of a phosphorylated protein to the 21-nucleotide repeat sequence and that the response to tax is partially dependent upon binding of the phosphorylated protein. The results suggest a model in which the phosphorylation of a transcription factor by protein kinase A regulates HTLV-I gene expression.
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PMID:Protein kinase A-dependent binding of a nuclear factor to the 21-base-pair repeat of the human T-cell leukemia virus type I long terminal repeat. 230 43

A newly synthesized compound, H-87, N-[2-(p-bromo cinnamylmethylamino)ethyl]-5-isoquinolinesulfonamide was found to be a potent and selective inhibitor of cyclic AMP-dependent protein kinase. The effects of H-87 on in vitro sensitivities of various P388 murine leukemia cell lines resistant to several antitumor agents were examined. H-87 significantly potentiated the cytotoxic effects of Adriamycin (ADR), daunorubicin (DAU), vincristine (VCR) and vinblastine (VBL) on P388 cells resistant to these antitumor agents but hardly influenced the effects of mitomycin C (MMC), 5-fluorouracil (5-FU) and cisplatin (CDDP) on ADR-resistant P388 cells (P388/ADR) and P388 phenotypes resistant to the corresponding antitumor agents. H-87 promoted the accumulation of VBL much more in P388/ADR cells than in the sensitive cells by inhibiting the energy-dependent extrusion of the antitumor agent from the cells. These results suggest that this novel isoquinoline-sulfonamide derivative, H-87, overcomes the multidrug resistance by inhibiting the phosphorylation of an outward drug transport system through cyclic AMP-dependent protein kinase.
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PMID:Circumvention of multidrug resistance in P388 murine leukemia cells by a novel inhibitor of cyclic AMP-dependent protein kinase, H-87. 233 96

Acute leukemia is the result of a defect in the process of normal cellular differentiation. Human leukemia cell lines (HL60, RDFD-2) have been established which can be induced to differentiate into phenotypically mature cells by a variety of agents. Recent evidence suggests that cyclic adenosine 3'-5'-monophosphate (cAMP) and the cAMP dependent protein kinase (cAMP-dPK) may be intimately involved in myeloid differentiation. The addition of low levels of a wide variety of inducers of a diverse chemical nature, dimethylformamide (DMF), retinoic acid (RA), actinomycin D (ACT-D) or hypoxanthine (HPX) prior to the addition of 8-bromo-cyclic adenosine 3'-5' monophosphate (8-Br-cAMP), cholera toxin (CT) or the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX) results in marked potentiation of differentiation of both HL60 and RDFD cells as manifested by the acquisition of the antigen OKM-1, the ability to reduce nitroblue tetrazolium or expression of the chemotactic receptor. Potentiation of differentiation is also observed when 8-Br-cAMP, CT or IBMX is added prior to the addition of either RA, DMF, ACT-D or HPX. These results suggest a role for cAMP in myeloid differentiation.
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PMID:Potentiation between intracellular cyclic-AMP-elevating agents and inducers of leukemic cell differentiation. 241 82

Antibodies against phosphotyrosine are a powerful tool with which to identify proteins phosphorylated on tyrosine residues, such as viral oncogene-encoded transforming proteins and their cellular protein substrates. Probed on human leukemia cell lines, phosphotyrosine antibodies recognized a 210,000-molecular-weight protein (p210) in K562 cells, a cell line derived from a Philadelphia (Ph)'-positive chronic myelogenous leukemia (CML), but recognized no protein in control Ph'-negative non-CML leukemia cells. The p210 protein was also recognized by antisera against v-abl-encoded polypeptides and displayed kinase activity, phosphorylating itself on tyrosine, in an immunocomplex kinase assay. These data are consistent with reported findings of the expression of a recombined bcr-abl gene in Ph'-positive CML cells, leading to the synthesis of an altered p210c-abl protein endowed with tyrosine kinase activity. Phosphotyrosine antibodies also detected the expression of the p210c-abl protein in fresh bone marrow cells harvested from CML patients in blast crisis. Besides the p210c-abl protein kinase, phosphotyrosine antibodies recognized other proteins with molecular weights of 110,000, 68,000, and 36,000 (p110, p68, and p36) in K562 cells. When [gamma-32P]ATP was added to nonionic detergent-extracted cells, these proteins became phosphorylated on tyrosine, as confirmed by phosphoamino acid analysis. A comparison with fibroblasts transformed by the v-abl, v-src, and v-fps oncogenes suggested the identity of the p36 protein with the common 36-kilodalton protein substrate of viral oncogene-encoded tyrosine kinases. Enhanced tyrosine phosphorylation of cellular proteins is thus a feature shared by cells transformed by v-abl and cells expressing a rearranged bcr-abl gene.
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PMID:Phosphotyrosine antibodies identify the p210c-abl tyrosine kinase and proteins phosphorylated on tyrosine in human chronic myelogenous leukemia cells. 243 Dec 86

To test whether cellular protein kinases exist that phosphorylate D-amino acid residues, a method was developed for separating O-phospho-D-serine from O-phospho-L-serine and O-phospho-L-tyrosine from O-phospho-D-tyrosine. This was accomplished by converting these amino acids to the L-leucyl dipeptide derivatives followed by separation of the diastereomers by anion-exchange high-performance liquid chromatography. The enantiomeric content of these D- and L-residues were measured in hydrolysates of 32P-labeled proteins produced by the protein kinases of human erythrocytes and the tyrosyl protein kinase of the Abelson leukemia virus. We found no measurable D-phosphoserine in erythrocyte membrane proteins under conditions where a 1% content of this residue relative to L-phosphoserine would have been detected. These values can be used to place an upper hypothetical limit on the fraction of erythrocyte protein kinase activity that is specific for serine residues in the D-configuration. In separate experiments, we examined the specificity of the tyrosyl protein kinases. We found that all of the phosphotyrosine that we isolated from the erythrocyte band 3 NH2-terminal fragment and from the autophosphorylation of the Abelson virus tyrosyl kinase was in the L-configuration.
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PMID:The stereospecificity of protein kinases. 244 31

Expression of cellular src-gene product (p60c-src) in human leukemia-lymphoma cell lines was analysed by flow cytometry using a monoclonal antibody (McAb), H2B4 which recognizes p60c-src protein in human cells. In several human leukemia-lymphoma cell lines (K562, Namalva, HL60, U937), p60c-src expression was higher than in peripheral mononuclear cells from healthy volunteers. Some non-lymphoid leukemia cells can be induced to differentiate into monocyte-macrophages by 12-O-tetradecanoyl phorbol-13-acetate (TPA). K562 cells were also induced to differentiate not only morphologically but also functionally into monocyte-macrophages by TPA. Flow cytometric analyses using the McAb H2B4 revealed that the amount of p60c-src expression in K562 cells markedly decreased during TPA induced differentiation. The activity of protein kinase associated with p60c-src in K562 cells was determined employing IgG of immunized rabbit serum specific for p60c-src. The immunized rabbit IgG heavy chain phosphorylation by protein kinase also decreased after the induced differentiation. We detected p60c-src protein in acute lymphoid leukemia cells as well as acute non-lymphoid leukemia cells freshly isolated from patients. The amount of p60c-src protein decreased in some acute non-lymphoid leukemia cases, but it increased in others after TPA induced differentiation. No correlation was observed between FAB classification of acute leukemias and the amount of endogenous p60c-src expression.
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PMID:Alteration of p60c-src expression in human leukemia-lymphoma cells correlated with induced differentiation. 245 97

The human T-cell leukemia virus type I (HTLV-I) trans-activator (tax)-inducible enhancer was localized to three copies of 21-base-pair repeats within the long terminal repeat. Interestingly, the TGACG motif found in the center of the 21-base-pair tax-responsive element (TRE) is also present in the cyclic AMP (cAMP)-responsive elements (CREs) and activating transcription factor (ATF)-binding sites. In this study, we demonstrate that the three TRE-binding proteins, TREB-1, TREB-2, and TREB-3, also bind to various CREs and ATF-binding sites and that the TREs can confer upon a heterologous promoter responsiveness to various inducing agents, including tax, cAMP, and E1a. Furthermore, the transcriptional activation of the HTLV-I promoter by tax can be inhibited by several protein kinase inhibitors, including sangivamycin. Our results indicate that the TREs, CREs, and ATF-binding sites are similar cis-acting elements and further suggest (i) that the transcriptional activation of the HTLV-I promoter by tax involves the action of a protein kinase and (ii) that induction by tax, cAMP, and E1a might be mediated by distinct factors or kinases.
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PMID:Utilization of signal transduction pathway by the human T-cell leukemia virus type I transcriptional activator tax. 247 73

Control mechanisms of normal differentiation are disrupted in cancer cells but can be restored by treatment with site-selective cAMP analogs. The cellular events associated with such changes entail compartmental redistribution of the cAMP-dependent protein kinase type II regulatory subunit, RII beta. The results of this study indicate that the molecular mechanisms of action involve changes in specific DNA-binding activity of putative transcription factors. Gel retardation analyses revealed that nuclear extracts from cells of various human cancer cell lines [colon cancer (LS-174T), gastric cancer (TMK-1), and leukemia (K-562)] and rodent pheochromocytoma (PC12) show a concentration-dependent increase in binding activity to a synthetic DNA that contained the cAMP-responsive element 5'-TGACGTCA-3' after treatment with 8-Cl-cAMP. Such an increase in cAMP-responsive element binding activity was not observed in the 8-C1-cAMP-unresponsive MKN-1 gastric cancer cells. These findings indicate that the antitumor activity of site-selective cAMP analogs may reside in the induction of transcription factors that restore normal gene regulation in cancer cells.
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PMID:Site-selective 8-Cl-cAMP which causes growth inhibition and differentiation increases DNA (CRE)-binding activity in cancer cells. 252 74

Studies were conducted to determine the possible involvement of DNA topoisomerase II (Topo II) in the induction of differentiation in two human promyelocytic HL-60 leukemia cell variants that are either susceptible or resistant to differentiation induced by phorbol-12-myristate-13-acetate (PMA), a protein kinase C activator. The acquisition of maturation markers and changes in the activity, level, and phosphorylation of Topo II were determined after treatment with either novobiocin, a Topo II inhibitor, or PMA. Novobiocin at 50-150 microM induced differentiation in the HL-205 cells but not in the HL-525 cells, although both cell types were equally susceptible to novobiocin-evoked cytotoxicity. In both cell types, novobiocin induced similar reductions in topoisomerase I activity but different reductions in Topo II activity. Treatment with novobiocin at 150 microM for 6 h or at 2 mM for 30 min resulted in a 4-fold or higher reduction in Topo II activity in the differentiation-susceptible HL-205 cells but not in the differentiation-resistant HL-525 cells. A differential response in Topo II activity was also observed after treatment with PMA. The novobiocin-evoked decrease in Topo II activity seems to be due to an enhanced enzyme proteolysis, whereas the PMA-elicited decrease in Topo II activity is associated with an increase in Topo II phosphorylation. 1-(5-Isoquinolinesulfonyl)-2-methylpiperazine, which is an inhibitor of protein kinases, including protein kinase C, diminished the novobiocin-elicited proteolysis of Topo II and the PMA-induced Topo II phosphorylation, as well as the decrease in Topo II activity and the acquisition of differentiation markers induced by either novobiocin or PMA. These results suggest that induction of differentiation in HL-60 cells by novobiocin or PMA is associated with a reduction in Topo II activity, mediated directly or indirectly by a protein kinase(s), perhaps protein kinase C.
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PMID:Novobiocin- and phorbol-12-myristate-13-acetate-induced differentiation of human leukemia cells associated with a reduction in topoisomerase II activity. 253 41

Abelson murine leukemia virus (A-MuLV) encodes a single protein product, a tyrosine-specific protein kinase, whose activity is necessary for cell transformation by this retrovirus. Using a defined medium culture system, we demonstrate that transformation of NIH 3T3 fibroblasts by A-MuLV abrogates their normal requirement for platelet-derived growth factor (PDGF) for cell growth. Analysis of constructed insertional mutant viruses revealed an absolute correlation between A-MuLV-encoded tyrosine kinase activity and PDGF-independent fibroblast growth. Sequences of the provirus not required for kinase activity appeared unnecessary for abrogating the fibroblast requirement for PDGF. Conversely, sequences required for kinase activity appeared necessary, suggesting that induction of PDGF-independent fibroblast growth, like cell transformation, is a function of this tyrosine kinase. Fibroblasts transformed by a partially transformation-defective mutant demonstrated incomplete morphological transformation but were still independent of PDGF for growth. Thus, the processes of full morphological transformation and growth factor independence can be partially dissociated.
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PMID:Abelson murine leukemia virus induces platelet-derived growth factor-independent fibroblast growth: correlation with kinase activity and dissociation from full morphologic transformation. 253 21


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