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)

A novel series of aroyl-pyrrolyl-hydroxy-amides (APHAs) active as histone deacetylase (HDAC) inhibitors has been reported. The new derivatives were designed by replacing the benzene ring of the prototype 1 with both aromatic and aliphatic, monocyclic and polycyclic rings (compounds 3a-i), or by inserting a number of substituents on the methylene linker of 1 (compounds 4a-l). Compounds 3a-i and 4a-l were active at sub-micromolar level against the maize deacetylases HD1-B (class I), HD1-A (class II), and HD2. Tested at 5 microM against human HDAC1 and HDAC4, 3b, 4a, and 4j showed significant HDAC1 inhibition, whereas on HDAC4 only 4a was highly effective. On the human leukemia U937 cell line, the same compounds did not alter the cell cycle phases and failed in inducing apoptosis. However, they displayed granulocytic differentiation at 5 microM, with 3b being the most potent (76% CD11c positive cells). Tested to evaluate their effects on histone H3 and alpha-tubulin acetylation, 3b and 4a showed high H3 acetylation, whereas 4a and 4b were the most potent with alpha-tubulin as a substrate.
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PMID:Novel pyrrole-containing histone deacetylase inhibitors endowed with cytodifferentiation activity. 1748 99

Bcr-Abl-independent signaling pathways are known to be involved in imatinib resistance in some patients with chronic myelogenous leukemia (CML). In this study, to find new targets for imatinib-resistant CML displaying loss of Bcr-Abl kinase target dependence, we isolated imatinib-resistant variants, K562/R1, K562/R2, and K562/R3, which showed profound declines of Bcr-Abl levels and its tyrosine kinase activity, from K562 cells. Importantly, the imatinib resistance mechanism in these variants also included aberrant acetylation of nonhistone proteins such as p53, Ku70, and Hsp90 that was due to upregulation of histone deacetylases (HDACs) and down-regulation of histone acetyltransferase (HAT). In comparison with K562 cells, the imatinib-resistant variants showed up-regulation of HDAC1, -2, and -3 (class I HDACs) and class III SIRT1 and down-regulation of CBP/p300 and PCAF with HAT activity, and thereby p53 and cytoplasmic Ku70 were aberrantly acetylated. In addition, these were associated with down-regulation of Bax and up-regulation of Bcl-2. In contrast, the class II HDAC6 level was significantly decreased, and this was accompanied by an increase of Hsp90 acetylation in the imatinib-resistant variants, which was closely associated with loss of Bcr-Abl. These results indicate that alteration of the normal balance of HATs and HDACs leads to deregulated acetylation of Hsp90, p53, and Ku70 and thereby leads to imatinib resistance, suggesting the importance of the acetylation status of apoptosis-related nonhistone proteins in Bcr-Abl-independent imatinib resistance. We also revealed that imatinib-resistant K562 cells were more sensitive to suberoylanilide hydroxamic acid, an HDAC inhibitor, than K562 cells. These findings may have implications for HDAC as a molecular target in imatinib-resistant leukemia cells.
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PMID:Bcr-Abl-independent imatinib-resistant K562 cells show aberrant protein acetylation and increased sensitivity to histone deacetylase inhibitors. 1756 22

The histone deacetylase (HDAC) inhibitor trichostatin A (TSA) and hexamethylene bisacetamide (HMBA), which lacks HDAC inhibitory activity, both possess the capacity to induce leukemia cell differentiation and to enhance the expression of a wide range of transiently transfected reporter genes in 3T3 Swiss cells. In addition, known inducers of leukemia cell differentiation, including hypoxanthine, diazepam, 6-thioguanine and phorbol 12-myristate 13-acetate, also exhibited the ability to enhance reporter gene expression, while randomly chosen compounds that did not induce leukemia cell differentiation did not enhance reporter gene expression. The activity of TSA in the transfection system was modified by co-expression of histone acetyltransferase p300 and HDAC1; whereas, that of HMBA was enhanced by co-expression of the TATA-binding protein TBP. The stimulatory effects of diverse chemical inducers on transiently transfected genes suggest the existence of multiple exploitable targets for the selection of novel inducers of differentiation that function as modulators of gene activity.
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PMID:Relationship between the induction of leukemia cell differentiation and the enhancement of reporter gene expression in 3T3 Swiss cells. 1762 56

Innate immune cells such as natural killer (NK) cells play a crucial role in antitumor immune responses. NKG2D is a major activating immunoreceptor expressed in not only NK cells but also CD8+ T cells and shows cytotoxicity against tumors by recognizing its ligands major histocompatibility complex class I-related chain A and B (MICA and MICB) on tumor cells. Recently, it has been suggested that NKG2D-mediated cytotoxicity correlates with the expression levels of NKG2D ligands on target cells. In this study, we were able to increase the expression levels of MICA and MICB on leukemic cell lines and patients' leukemic cells by treatment with trichostatin A (TsA), a histone deacetylase (HDAC) inhibitor. Chromatin immunoprecipitation (ChIP) assays revealed that treatment with TsA resulted in increased acetylation of histone H3 and decreased association with HDAC1 at the promoters of MICA and MICB. Intriguingly, upregulation of MICA and MICB by treatment with TsA led to enhancement of the susceptibility of leukemic cells to the cytotoxicity of NKG2D-expressing cells. Our results suggest that regulation of the expression of NKG2D ligands by treatment with chromatin-remodeling drugs may be an attractive strategy for immunotherapy.
Leukemia 2007 Oct
PMID:Regulation of the expression of MHC class I-related chain A, B (MICA, MICB) via chromatin remodeling and its impact on the susceptibility of leukemic cells to the cytotoxicity of NKG2D-expressing cells. 1762 2

We have reported that a novel c-Myc-binding protein, MM-1, repressed the E-box-dependent transcription activity of c-Myc by recruiting the HDAC1 complex via TIF1beta/KAP1, a transcriptional corepressor. We have also reported that a mutation of A157R in MM-1, which is often observed in patients with leukemia or lymphoma, abrogated all of the repressive activities of MM-1 toward c-Myc, indicating that MM-1 is a novel tumor suppressor. In this study, we found that MM-1 was bound to a component of proteasome and stimulated degradation of c-Myc in human cells. Knockdown of endogenous MM-1 in human HeLa cells by introduction of siRNA against MM-1 stabilized the endogenous c-Myc. To identify proteins that participate in c-Myc degradation by MM-1, in vivo and in vitro binding assays were carried out. The results showed that MM-1 directly bound to Rpt3, a subunit of 26S proteasome, and that c-Myc directly bound to Skp2, which recruited ElonginC, ElonginB and Cullin2, thereby forming a novel ubiquitin E3 ligase. Knockdown of endogenous Cullin2 stabilized the endogenous c-Myc. Thus, MM-1 is a factor that connects c-Myc to the ubiquitin E3 ligase and the proteasome.
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PMID:MM-1 facilitates degradation of c-Myc by recruiting proteasome and a novel ubiquitin E3 ligase. 1778 14

Curcumin, the active chemical of the Asian spice turmeric, exhibits anticancer activity in several human cancer cell lines. We previously have proved that curcumin was a new member of the histone deacetylases (HDAC) inhibitors, while constitutive nuclear factor kappa B (NF-kappaB) is believed to be a crucial event for enhanced proliferation and survival of malignant cells. Here, we investigate the effect of curcumin on the activation of NF-kappaB signal molecule in Raji cells to explore its relationship with HDACs or p300/CREB binding protein (CBP). Curcumin presented striking proliferation inhibition potency on Raji cells in vitro, with the IC(50) value for 24 hr being 25 micromol/l. Significant decreases in the amounts of p300, HDAC1 and HDAC3 were detected after treatment with curcumin. These suppressing effects were more pronounced when the administered dose increased. The protection degradation of HDAC1 and p300 by MG-132 could be partially reversed by curcumin. Furthermore, curcumin could also prevent degradation of I kappaB alpha and inhibit nuclear translocation of the NF-kappaB/p65 subunit, as well as expression of Notch 1, induced by tumour necrosis factor-alpha. The results suggest that the depressive effect of curcumin on NF-kappaB signal transduction pathway may be mediated via the various components of the HDACs and p300/Notch 1 signal molecules, and may represent a new remedy for acute leukaemia.
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PMID:Curcumin, both histone deacetylase and p300/CBP-specific inhibitor, represses the activity of nuclear factor kappa B and Notch 1 in Raji cells. 1792 89

R306465 is a novel hydroxamate-based histone deacetylase (HDAC) inhibitor with broad-spectrum antitumour activity against solid and haematological malignancies in preclinical models. R306465 was found to be a potent inhibitor of HDAC1 and -8 (class I) in vitro. It rapidly induced histone 3 (H3) acetylation and strongly upregulated expression of p21waf1,cip1, a downstream component of HDAC1 signalling, in A2780 ovarian carcinoma cells. R306465 showed class I HDAC isotype selectivity as evidenced by poor inhibition of HDAC6 (class IIb) confirmed by the absence of downregulation of Hsp90 chaperone c-raf protein expression and tubulin acetylation. This distinguished it from other HDAC inhibitors currently in clinical development that were either more potent towards HDAC6 (e.g. vorinostat) or had a broader HDAC inhibition spectrum (e.g. panobinostat). R306465 potently inhibited cell proliferation of all main solid tumour indications, including ovarian, lung, colon, breast and prostate cancer cell lines, with IC50 values ranging from 30 to 300 nM. Haematological cell lines, including acute lymphoblastic leukaemia, acute myeloid leukaemia, chronic lymphoblastic leukaemia, chronic myeloid leukaemia, lymphoma and myeloma, were potently inhibited at a similar concentration range. R306465 induced apoptosis and inhibited angiogenesis in cell-based assays and had potent oral in vivo antitumoral activity in xenograft models. Once-daily oral administration of R306465 at well-tolerated doses inhibited the growth of A2780 ovarian, H460 lung and HCT116 colon carcinomas in immunodeficient mice. The high activity of R306465 in cell-based assays and in vivo after oral administration makes R306465 a promising novel antitumoral agent with potential applicability in a broad spectrum of human malignancies.
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PMID:R306465 is a novel potent inhibitor of class I histone deacetylases with broad-spectrum antitumoral activity against solid and haematological malignancies. 1800 Apr 99

Reciprocal chromosomal translocations at the MLL gene locus result in expression of novel fusion proteins, such as MLL-ENL, associated with leukemia. The three PHD finger cassette, one of the highly conserved domains in MLL, is absent in all fusion proteins. This domain has been shown to interact with Cyp33, a cyclophilin which enhances the recruitment of histone deacetylases (HDAC) to the MLL repression domain and mediates HOX gene repression. Insertion of the third PHD finger of MLL into MLL-ENL allows the recruitment of Cyp33 and, subsequently, HDAC1 to the fusion protein. Furthermore, expression of the fusion protein with the PHD finger insertion mediates the down-regulation of the HOXC8 gene expression in a Cyp33-dependent manner. Finally, the addition of the PHD finger domain or the third PHD finger alone into MLL-ENL blocks the hematopoietic stem cell immortalization potential of the fusion protein in serial plating colony assays. Insertion of only the first and second PHD fingers has no such effect. These data support the hypothesis that the binding of Cyp33 to the MLL third PHD finger switches the MLL function from transactivation to repression. In the immortalizing MLL fusion protein, the loss of the PHD fingers, in combination with the gain of the activation domain of ENL or of other partner proteins, makes the fusion protein a constitutive transactivator. This leads to constitutive overexpression of MLL target genes that block stem cell commitment and promote stem cell renewal, probably the first step in MLL-related leukemogenesis.
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PMID:Loss of MLL PHD finger 3 is necessary for MLL-ENL-induced hematopoietic stem cell immortalization. 1867 43

Telomerase activity, which has fundamental roles in development and carcinogenesis, strongly depends on the expression of human telomerase reverse transcriptase (hTERT), its catalytic subunit. In this report, we show that the basic helix-loop-helix factor, TAL1 (T-cell acute lymphoblastic leukemia 1), is a negative regulator of the hTERT promoter. Indeed, TAL1 overexpression leads to a decrease in hTERT mRNA abundance and hence to reduced telomerase activity. Conversely, suppression of TAL1 by RNA interference in Jurkat cells increases hTERT expression. Analysis by chromatin immunoprecipitation assays showed that TAL1 binds to the hTERT proximal promoter and recruits HDAC1. Considering the relationship recently established between TAL1 and the human T-cell leukemia virus type 1 (HTLV-1) Tax protein, which was confirmed in T lymphocyte clones derived from adult T-cell leukemia patients, we analyzed the effect of TAL1 with respect to the earlier characterized effects of Tax and HBZ (HTLV-1 basic leucine zipper) on hTERT expression. TAL1 was observed to reinforce the negative effect of Tax, whereas hTERT transactivation by the HBZ-JunD complex was repressed by TAL1 overexpression. Moreover, HBZ was found to induce proteasome-mediated degradation of TAL1. These observations support a model in which Tax and TAL1 by repressing hTERT would initially favor genomic instability, whereas expression of factors such as HBZ allows at a later stage an increase in hTERT production and consequently in telomerase activity.
Leukemia 2009 Nov
PMID:Inhibition of the hTERT promoter by the proto-oncogenic protein TAL1. 1958 3

How tumour suppressor p53 bifurcates cell cycle arrest and apoptosis and executes these distinct pathways is not clearly understood. We show that BAX and PUMA promoters harbour an identical MAR element and are transcriptional targets of SMAR1. On mild DNA damage, SMAR1 selectively represses BAX and PUMA through binding to the MAR independently of inducing p53 deacetylation through HDAC1. This generates an anti-apoptotic response leading to cell cycle arrest. Importantly, knockdown of SMAR1 induces apoptosis, which is abrogated in the absence of p53. Conversely, apoptotic DNA damage results in increased size and number of promyelocytic leukaemia (PML) nuclear bodies with consequent sequestration of SMAR1. This facilitates p53 acetylation and restricts SMAR1 binding to BAX and PUMA MAR leading to apoptosis. Thus, our study establishes MAR as a damage responsive cis element and SMAR1-PML crosstalk as a switch that modulates the decision between cell cycle arrest and apoptosis in response to DNA damage.
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PMID:Coordinated regulation of p53 apoptotic targets BAX and PUMA by SMAR1 through an identical MAR element. 2007 64


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