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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have demonstrated that the gibbon ape leukemia virus (GALV) enhancer AP-1 element and the simian virus 40 AP-1 enhancer element bind different factors in HeLa nuclear extracts. A 39-kilodalton HeLa nuclear protein and the c-fos protein bind to the GALV element. Antibodies to c-fos abolish binding to the GALV AP-1 site. In contrast, anti-c-fos immunoglobulin fails to inhibit formation of the simian virus 40-specific complex from extracts of HeLa cells. Thus, AP-1-binding complexes are subject to compositional variation at different binding sites.
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PMID:Distinct factors bind the AP-1 consensus sites in gibbon ape leukemia virus and simian virus 40 enhancers. 253 54

The Fos protein complex and several Fos-related antigens bind directly or indirectly to a common sequence element that is similar to the consensus binding site for HeLa cell activator protein 1 (AP-1). This element is present in a negative regulatory sequence in the differentiation-sensitive adipocyte gene, aP2; in a transcriptional enhancer for the Gibbon ape leukemia virus; and in a region of the human immunodeficiency virus (HIV) long terminal repeat partially characterized as a negative regulatory element. The protein level and binding activity of Fos and Fos-related antigens increase rapidly after calcium ionophore treatment of a CD4+ human lymphoblast cell line, H9. These data suggest that several proteins may associate with the AP-1 binding site. Moreover, temporally regulated control of the level of each protein could represent a mechanism for modulation of these putative mediators of gene expression.
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PMID:The Fos complex and Fos-related antigens recognize sequence elements that contain AP-1 binding sites. 296 84

Human monoblastoid leukemia U937 cells differentiate to monocyte/macrophage upon treatment with phorbol ester, 12-o-tetradecanoylphorbol-13-acetate (TPA). Previous studies, including our own, have demonstrated that drug-induced differentiation of leukemia cells is associated with genetic and enzymatic activations of protein tyrosine phosphatases (PTPases). In this study, to further investigate a relationship between PTPase activation and leukemic differentiation, we established TPA-resistant U937 variant UT16 cells. Unlike known TPA-resistant cells whose resistance is mainly due to lack or down modulation of protein kinase C (PKC), UT16 cells showed TPA-induced activation of PKC, Raf-1, and ERK/MAP kinases similar to the parental U937 cells. Interestingly, however, UT16 cells exhibited altered binding activity of AP-1 complexes, decreased ability to induce c-jun and c-fos gene expressions, and failure to differentiate to a monocytic lineage. Based on these observations, UT16 cells could be considered a novel type of TPA-resistant cell. Among UT16 cells, most of TPA-inducible PTPase genes, PTP-1C, PTP-MEG2, P19-PTP, HPTP epsilon, and PTP-U1, did not respond to TPA. Consistently, TPA increased PTPase enzymatic activity in U937 but not in UT16 cells. Taken together, activation of PTPases is well correlated with TPA-induced differentiation of U937 cells. These findings indicate that gene expression and enzymatic activity of some PTPase isozymes described here are regulated by a TPA-mediated signaling event and are likely to be used as biomarkers for the monocytic differentiation of myeloid leukemia cells.
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PMID:Phorbol ester-resistant monoblastoid leukemia cells with a functional mitogen-activated protein kinase cascade but without responsive protein tyrosine phosphatases. 747 24

Inflammatory genes are regulated in cells of monocyte (Mo) lineage by a variety of cellular encounters, including adhesion mediated by integrins. The role of the beta 1 family of integrins in the direct induction of immediate early gene expression was analyzed by using the tissue factor (TF) gene. Engagement of alpha 4 or beta 1 on Mo, but not members of the beta 2 integrin family, with specific mAbs as surrogate ligands immediately and directly induced high level surface expression of TF, and accumulation of TF mRNA, as well as production of TNF-alpha and HIV-1 virus. The mechanism responsible for induction of TF gene transcription mediated by the engagement of alpha 4 or beta 1 was elucidated by using THP-1 monoblastic leukemia cells. Functional analysis of plasmids containing the TF promoter expressing the luciferase reporter gene identified a cis-acting integrin-responsive element (InRE), which contained two AP-1 sites as well as a single kappa B-like site. Mutation of either the AP-1 sites or kappa B-like site greatly diminished responsiveness to integrin engagement. This InRE also conferred responsiveness to a heterologous promoter in the same reporter plasmid. Binding of mAbs to either alpha 4 or beta 1 led to nuclear translocation of the c-Rel/p65 heterodimer that preferentially bound to the TF kappa B-like site. In contrast, constitutive binding of AP-1 proteins to the two AP-1 sites was not increased by alpha 4 or beta 1 integrin engagement. These studies expand knowledge of integrin regulation of immediate early gene expression in Mo and molecular encounters that are inferred to play an active role in Mo effector functions.
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PMID:Integrin regulation of an inflammatory effector gene. Direct induction of the tissue factor promoter by engagement of beta 1 or alpha 4 integrin chains. 753 94

Ceramide has emerged as a novel lipid mediator in cell proliferation, differentiation, and apoptosis. In this work, we demonstrate that the levels of c-jun mRNA, c-Jun protein, and DNA binding activity of a nuclear transcription factor AP-1 to 12-o-tetradecanoylphorbol 13-acetate responsive elements all increased following treatment with the cell-permeable ceramide, N-acetylsphingosine in human leukemia HL-60 cells. N-Acetylsphingosine (1-10 microM) increased the levels of c-jun mRNA in a dose-dependent manner, and maximal expression was achieved 1 h after treatment. Increase of c-jun expression treated with 5 microM N-acetyldihydrosphingosine, which could not induce apoptosis, was one third of that with 5 microM N-acetylsphingosine. Ceramide-induced growth inhibition and DNA fragmentation were both prevented by treatment with curcumin, 1,7-bis[4-hydroxy-3-methoxy-phenyl]-1,6-heptadiene-3,5-dione (an inhibitor of AP-1 activation), or antisense oligonucleotides for c-jun. These results suggest that the transcription factor AP-1 is critical for apoptosis in HL-60 cells and that an intracellular sphingolipid mediator, ceramide, modulates a signal transduction inducing apoptosis through AP-1 activation.
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PMID:Requirement of AP-1 for ceramide-induced apoptosis in human leukemia HL-60 cells. 759 95

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

The biological activity of a novel synthetic retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (AHPN) was investigated in human breast carcinoma (HBC) cells. Although capable of selective binding to the RAR gamma nuclear receptor, AHPN inhibited the growth of a number of HBC cell lines via RAR- or RXR-independent pathways. AHPN also inhibited the growth of the human leukemia cell line HL-60R which does not possess functional RARs. RA significantly inhibited AP-1 mediated gene activation in MCF-7 cells while AHPN displayed no such anti-AP-1 activity. Retinoids normally are cytostatic in their inhibition of breast carcinoma growth and permit cell proliferation upon their removal, wher as AHPN induced G0/G1 arrest within 6h followed by apoptosis. In MCF-7 cells that harbor wild type p53, AHPN-induced G0/G1 arrest and apoptosis was accompanied by p53-independent regulation of WAF1/CIP1 as well as bax mRNA levels while bcl-2 mRNA levels were decreased. In MDA-MB-231 cells which possess a mutant p53, AHPN-mediated G0/G1 arrest and apoptosis was also associated with a concomitant up regulation of WAF1/CIP1 mRNA while these cells did not express bax or bcl-2 messages. Thus AHPN represents a novel retinoid that induces G0/G1 arrest and apoptosis via a unique pathway which appears to involve activation of known downstream effectors of p53 in a p53-independent manner.
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PMID:p53 independent G0/G1 arrest and apoptosis induced by a novel retinoid in human breast cancer cells. 763 Jun 33

Moloney murine leukemia virus (Mo-MuLV) is a thymotropic and leukemogenic retrovirus which causes T lymphomas. The long terminal repeat (LTR) of Mo-MuLV affects the regulation of a number of cellular genes, including collagenase IV, monocyte chemoattractant protein-1, and c-jun genes, all of which contain 12-O-tetradecanoylphorbol-13-acetate-responsive element consensus sites within their promoters. We report here that Mo-MuLV stimulates the collagenase IV gene through transcription factor AP-1, and that the expression of a subgenomic portion of Mo-MuLV LTR alone is sufficient for this effect. Transient or stable expression of the viral LTR increases cellular AP-1 DNA binding activity. The collagenase IV 12-O-tetradecanoylphorbol-13-acetate-responsive element consensus sequence was shown to be required for this trans-activation. Deletions or mutations of this consensus site which abolished AP-1 binding also abolished trans-activation by the LTR. Transient or stable transfection of the viral LTR into cells stimulated c-jun gene expression, suggesting one mechanism whereby the viral LTR may induce cellular AP-1 activity. Thus, the Mo-MuLV LTR, through activation of the transcription factor AP-1, is capable of regulating cellular gene expression, including the induction of proto-oncogenes. This activity may be relevant to the mechanisms whereby retroviruses which do not contain oncogenes induce neoplasia.
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PMID:The Moloney leukemia retroviral long terminal repeat trans-activates AP-1-inducible genes and AP-1 transcription factor binding. 777 15

Adult T-cell leukemia (ATL) associated with HTLV-1 infection is characterized by the development of hypercalcemia in over two thirds of patients. Dysregulation of cellular gene transcription by viral proteins is an emerging paradigm for molecular pathogenesis of disease. A recent example is the parathyroid hormone-related protein (PTHrP) gene, which has been implicated in the hypercalcemia of ATL, and is transactivated by the HTLV-1 tax and HTLV-11 tax proteins. PTHrP is expressed at high levels in leukemia cells derived from ATL patients, as well as in asymptomatic HTLV-1 positive carriers. This article reviews the interaction of the HTLV-1 transcriptional regulator tax with the PTHrP promoter. Tax mediates its effects on PTHrP via cellular transcription factors AP-2 and AP-1, and transactivation via an AP-2 motif represents a novel interaction of tax with a cellular transcription factor.
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PMID:Hypercalcemia, parathyroid hormone-related protein expression and human T-cell leukemia virus infection. 781 98

We have examined the expression of the interleukin 1 beta (IL-1 beta) gene during the granulocytic differentiation of two promyeloid leukemia cell lines, HL-60 and NB4. HL-60 is known to differentiate along the granulocytic pathway after treatment with 13-trans-retinoic acid (13-trans-RA), whereas treatment with phorbol myristate acetate (PMA) leads to development of mature macrophages. NB4 cells are derived from the bone marrow of an acute promyelocytic leukemia (APL) patient in relapse, have a translocated RA receptor-alpha, and are converted into nondividing granulocytes by 13-trans-RA treatment. When HL-60 or NB4 were cultured in the presence of 13-trans-RA, IL-1 beta mRNA and protein levels were increased. In the more mature THP-1 cells which are induced to macrophage-like cells by 13-trans-RA treatment, RA was unable to induce any IL-1 beta expression, implying that the effect of 13-trans-RA is associated with granulocytic differentiation. Moreover, PMA and 13-trans-RA had a strong synergistic effect in the induction of IL-1 beta gene expression. Nuclear run-off analysis indicated that the increased IL-1 beta gene expression was due to an enhanced rate of transcription. When the cells were transfected with an IL-1 beta-X-CAT reporter plasmid containing the -2982/-2748 promoter segment of the IL-1 beta gene conferring responsiveness to PMA, both NB4 and HL-60 cells responded with increased CAT activity when stimulated with 13-trans-RA alone. In contrast to PMA, 13-trans-RA was unable to increase AP-1 enhancer activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Activation of interleukin-1 beta gene expression during retinoic acid-induced granulocytic differentiation of promyeloid leukemia cells. 781 35


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