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)

Longstanding observations suggest that acetylation and/or amino-terminal tail structure of histones H3 and H4 are critical for eukaryotic cells. For Saccharomyces cerevisiae, loss of a single H4-specific histone acetyltransferase (HAT), Esa1p, results in cell cycle defects and death. In contrast, although several yeast HAT complexes preferentially acetylate histone H3, the catalytic subunits of these complexes are not essential for viability. To resolve the apparent paradox between the significance of H3 versus H4 acetylation, we tested the hypothesis that H3 modification is essential, but is accomplished through combined activities of two enzymes. We observed that Sas3p and Gcn5p HAT complexes have overlapping patterns of acetylation. Simultaneous disruption of SAS3, the homolog of the MOZ leukemia gene, and GCN5, the hGCN5/PCAF homolog, is synthetically lethal due to loss of acetyltransferase activity. This key combination of activities is specific for these two HATs because neither is synthetically lethal with mutations of other MYST family or H3-specific acetyltransferases. Further, the combined loss of GCN5 and SAS3 functions results in an extensive, global loss of H3 acetylation and arrest in the G(2)/M phase of the cell cycle. The strikingly similar effect of loss of combined essential H3 HAT activities and the loss of a single essential H4 HAT underscores the fundamental biological significance of each of these chromatin-modifying activities.
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PMID:Histone H3 specific acetyltransferases are essential for cell cycle progression. 1173 78

The human T-cell leukemia virus (HTLV-I)-encoded Tax protein is a potent transcriptional activator that stimulates expression of the integrated provirus. Biochemical studies indicate that Tax, together with cellular transcription factors, interacts with viral cAMP-response element enhancer elements to recruit the pleiotropic coactivators CREB-binding protein and p300. Histone acetylation by these coactivators has been shown to play a major role in activating HTLV-I transcription from chromatin templates in vitro. However, the extent of histone modification and the precise identity of the cellular regulatory proteins bound at the HTLV-I promoter in vivo is not known. Chromatin immunoprecipitation analysis was used to investigate factor binding and histone modification at the integrated HTLV-I provirus in infected T-cells (SLB-1). These studies reveal the presence of Tax, a variety of ATF/CREB and AP-1 family members (CREB, CREB-2, ATF-1, ATF-2, c-Fos, and c-Jun), and both p300 and CREB-binding protein at the HTLV-I promoter. Consistent with the binding of these coactivators, we observed histone H3 and H4 acetylation at three regions within the proviral genome. Histone deacetylases were also present at the viral promoter and, following their inhibition, we observe an increase in histone H4 acetylation on the HTLV-I promoter and a concomitant increase in viral RNA. Together, these results suggest that a variety of transcriptional activators, coactivators, and histone deacetylases participate in the regulation of HTLV-I transcription in infected T-cells.
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PMID:Transcription factor binding and histone modifications on the integrated proviral promoter in human T-cell leukemia virus-I-infected T-cells. 1238 57

1 We have examined the effect of the histone deacetylase inhibitors apicidin, trichostatin A (TSA) and n-butyrate on the histone acetylation and the differentiation of human eosinophilic leukemia HL-60 clone 15 cells into eosinophils. 2 Viability of the cells incubated with apicidin (100 nm), TSA (30 nm) or n-butyrate (500 microm) did not change significantly, but higher concentrations of apicidin (> or =300 nm) or TSA (> or =100 nm) decreased the viability when examined at day 1. 3 Apicidin (100 nm) as well as n-butyrate (500 microm) induced continuous acetylations of histone H4 and lysine14 residue on histone H3, while TSA (30 nm) induced transient acetylations. 4 After 6 days incubation, eosinophilic cells stained by Luxol-fast-blue were generated by apicidin (100 nm) and n-butyrate (500 microm) but not by TSA (30 nm). Other markers for differentiation into eosinophils such as changes in intracellular structure, and expressions of integrin beta7 and major basic protein, and the inhibition of cell proliferation were also induced by apicidin and n-butyrate but not by TSA. 5 Continuous acetylation of histone H4 achieved by repeated treatment with TSA (30 nm) at an interval of 12 h for more than three times induced such changes when examined on day 6. In addition, the induction was impaired by shortening the period of incubation with apicidin (100 nm) or n-butyrate (500 microm). 6 CCAAT/enhancer binding protein was continuously activated by apicidin (100 nm) and n-butyrate (500 microm), but was transiently activated by TSA (30 nm). 7 These findings suggest that the continuous acetylation of histones H3 and H4 is necessary for the differentiation of HL-60 clone 15 cells into eosinophils.
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PMID:Possible mechanism of action of the histone deacetylase inhibitors for the induction of differentiation of HL-60 clone 15 cells into eosinophils. 1521 May 80

We show that common heterochromatin antigenic protein markers [HP1alpha, -beta, -gamma and mono-, di-, and trimethylated histone H3 lysine 9 (H3K9)], although present in human blood progenitor CD34+ cells, differentiated lymphocytes, and monocytes, are absent in neutrophil granulocytes and to large extent, in eosinophils. Monomethylated and in particular, dimethylated H3K9 are present to variable degrees in the granulocytes of chronic myeloid leukemia (CML) patients, without being accompanied by HP1 proteins. In patients with an acute phase of CML and in acute myeloid leukemia patients, strong methylation of H3K9 and all isoforms of HP1 are detected. In chronic forms of CML, no strong correlations among the level of histone methylation, disease progression, and modality of treatment were observed. Histone methylation was found even in "cured" patients without Philadelphia chromosome (Ph) resulting from +(9;22)(q34;q11) BCR/ABL translocation, suggesting an incomplete process of developmentally regulated chromatin remodeling in the granulocytes of these patients. Similarly, reprogramming of leukemia HL-60 cells to terminal differentiation by retinoic acid does not eliminate H3K9 methylation and the presence of HP1 isoforms from differentiated granulocytes. Thus, our study shows for the first time that histone H3 methylation may be changed dramatically during normal cell differentiation. The residual histone H3 methylation in myeloid leukemia cells suggests an incomplete chromatin condensation that may be linked to the leukemia cell proliferation and may be important for the prognosis of disease treatment and relapse.
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PMID:Methylation of histones in myeloid leukemias as a potential marker of granulocyte abnormalities. 1550 73

Present studies show that LBH589, a novel cinnamic hydroxamic acid analog histone deacetylase inhibitor, induces acetylation of histone H3 and H4 and of heat shock protein 90 (hsp90), increases p21 levels, as well as induces cell-cycle G(1) phase accumulation and apoptosis of the human chronic myeloid leukemia blast crisis (CML-BC) K562 cells and acute leukemia MV4-11 cells with the activating length mutation of FLT-3. In MV4-11 cells, this was associated with marked attenuation of the protein levels of p-FLT-3, FLT-3, p-AKT, and p-ERK1/2. In K562 cells, exposure to LBH589 attenuated Bcr-Abl, p-AKT, and p-ERK1/2. Treatment with LBH589 inhibited the DNA binding activity of signal transducers and activators of transcription 5 (STAT5) in both K562 and MV4-11 cells. The hsp90 inhibitor 17-allyl-amino-demethoxy geldanamycin (17-AAG) also induced polyubiquitylation and proteasomal degradation of FLT-3 and Bcr-Abl by reducing their chaperone association with hsp90. Cotreatment with LBH589 and 17-AAG exerted synergistic apoptosis of MV4-11 and K562 cells. In the imatinib mesylate (IM)-refractory leukemia cells expressing Bcr-Abl with the T315I mutation, treatment with the combination attenuated the levels of the mutant Bcr-Abl and induced apoptosis. Finally, cotreatment with LBH589 and 17-AAG also induced more apoptosis of IM-resistant primary CML-BC and acute myeloid leukemia (AML) cells (with activating mutation of FLT-3) than treatment with either agent alone.
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PMID:Combination of the histone deacetylase inhibitor LBH589 and the hsp90 inhibitor 17-AAG is highly active against human CML-BC cells and AML cells with activating mutation of FLT-3. 1551 6

The B cell leukemia 11A protein (BCL11A/Evi9/CTIP1) has been implicated in hematopoietic cell development and malignancies. BCL11A is a transcriptional repressor that binds directly to a GC-rich motif and is also recruited to a promoter template via interaction with the orphan nuclear receptor, chicken ovalbumin upstream promoter transcription factor II. In both cases, BCL11A-mediated transcriptional repression is only minimally reversed by trichostatin A, suggesting the possible lack of involvement of class I or II histone deacetylases. Nonetheless, chromatin immunoprecipitation assays revealed that expression of BCL11A in mammalian cells resulted in deacetylation of histones H3 and/or H4 that were associated with the promoter region of a reporter gene. BCL11A-mediated transcriptional repression, as well as deacetylation of histone H3/H4 in BCL11A-transfected cells, was partially reversed by nicotinamide, an inhibitor of class III histone deacetylases such as SIRT1. SIRT1 was found to interact directly with BCL11A and was recruited to the promoter template in a BCL11A-dependent manner leading to transcriptional repression. These findings define a role for SIRT1 in transcriptional repression mediated by BCL11A in mammalian cells.
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PMID:BCL11A-dependent recruitment of SIRT1 to a promoter template in mammalian cells results in histone deacetylation and transcriptional repression. 1563 32

Rearrangements of the mixed-lineage leukemia gene MLL1 (MLL, HRX, ALL1), the human homologue of the Drosophila gene trithorax, are associated with aggressive acute leukemias in both children and adults. Transformation by rearranged forms of MLL1, including in-frame fusion proteins, partial tandem duplications, and amplification of MLL1 through upregulation of Hox gene and cofactor expression apparently results in a block in hematopoietic differentiation. MLL1 regulates Hox gene expression via direct promoter binding and histone H3 Lys 4 methylation mediated by the intrinsic methyltransferase activity of the SET domain. Mll1 knockout leads to loss of Hox gene expression, defects in hematopoiesis, and embryonic lethality. A close homologue, MLL2 is amplified in some solid tumors. MLL2 also has histone H3 Lys 4 methyltransferase activity that is dependent on menin, a protein mutated in multiple neoplasia type I (MEN1) and which is required for normal Hox expression. These findings underscore the importance of the MLL histone methyltransferases in development and disease.
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PMID:Mechanisms of transformation by MLL. 1566 55

In common with certain other lymphoid neoplasms, cells of the human lymphocytic leukemia lines 1873 and 1929 are asparagine (ASN) auxotrophs. Asparagine synthetase (ASY), which is a housekeeping gene, is repressed and the promoting region of the gene is highly methylated. We now demonstrate in these cells multiple levels in control of the expression of this gene, in a system of cocultivation with macrophages and other cell types. In this system, mediated by cell-to-cell contact, ASY becomes expressed by the leukemic cells and they become prototrophic. Demethylation of ASY occurs; it follows expression and is permanent over multiple cell generations, but the cells return to auxotrophy with rapid repression of ASY on removal from cell contact. With ASY expression, the associated histone H3 at lysine position 9 (H3K9) becomes acetylated and H3K4, methylated. In contrast to other systems, H3K9 methylation does not characterize the repressed state. The changes leading from repression to induction of ASY and demethylation parallel the physiological changes specific to functional maturation of normal lymphoid precursors. The lability of expression of ASY has potential significance in determining the sensitivity of leukemic cells to L-asparaginase.
Leukemia 2005 Mar
PMID:Epigenetic changes in the repression and induction of asparagine synthetase in human leukemic cell lines. 1567 23

Ikaros is a hematopoietic cell-specific zinc finger DNA binding protein that plays an important role in lymphocyte development. Genetic disruption of Ikaros results in T-cell transformation. Ikaros null mice develop leukemia with 100% penetrance. It has been hypothesized that Ikaros controls gene expression through its association with chromatin remodeling complexes. The development of leukemia in Ikaros null mice suggests that Ikaros has the characteristics of a tumor suppressor gene. In this report, we show that the introduction of Ikaros into an established mouse Ikaros null T leukemia cell line leads to growth arrest at the G0/G1 stage of the cell cycle. This arrest is associated with up-regulation of the cell cycle-dependent kinase inhibitor p27kip1, the induction of expression of T-cell differentiation markers, and a global and specific increase in histone H3 acetylation status. These studies provide strong evidence that Ikaros possesses the properties of a bona fide tumor suppressor gene for the T-cell lineage and offer insight into the mechanism of Ikaros's tumor suppressive activity.
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PMID:Ikaros induces quiescence and T-cell differentiation in a leukemia cell line. 1571 24

Chromosomal rearrangements and translocations play a major role in the pathogenesis of hematological malignancies. The trithorax-related mixed lineage leukemia (Mll) gene located on chromosome 11 is rearranged in a variety of aggressive human B and T lymphoid tumors as well as acute myeloid leukemia (AML) in both children and adults. It was first demonstrated for the yeast MLL homolog complex, Set1/COMPASS, and now for the MLL complex itself, that these complexes are histone methyltransferases capable of methylating the fourth lysine of histone H3. The post-translational modifications of histones by methylation have emerged as a key regulatory mechanism for both repression and activation of gene expression. Studies from several laboratories during the past few years have brought about a watershed of information defining the molecular machinery and factors involved in the recognition and modification of nucleosomal histones by methylation. In this review, we will discuss the recent findings regarding the molecular mechanism and consequences of histone modification by the MLL related protein containing complex COMPASS.
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PMID:A COMPASS in the voyage of defining the role of trithorax/MLL-containing complexes: linking leukemogensis to covalent modifications of chromatin. 1578 93


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