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 mammalian SWI/SNF chromatin remodeling complex is composed of more than 10 protein subunits, and plays important roles in epigenetic regulation. Each complex includes a single BRG1 or Brm molecule as the catalytic subunit. We previously reported that loss of Brm, but not BRG1, causes transcriptional gene silencing of murine leukemia virus-based retrovirus vectors. To understand the biological function and biogenesis of Brm protein, we examined seven cell lines derived from various human tumors that do not produce Brm protein. We show here that these Brm-deficient cell lines transcribe the Brm genes efficiently as detected by nuclear run-on transcription assay, whereas Brm mRNA and Brm hnRNA were undetectable by reverse transcription-polymerase chain reaction analysis. These results indicate that expression of Brm is strongly and promptly suppressed at the post-transcriptional level, through processing and transport of the primary transcript or through stability of mature Brm mRNA. This suppression was attenuated by transient treatment of these cell lines with HDAC inhibitors probably through indirect mechanism. Importantly, all of the treated cells showed prolonged induction of Brm expression after the removal of HDAC inhibitors, and acquired the ability to maintain retroviral gene expression. These results indicate that these Brm-deficient human tumor cell lines carry a functional Brm gene. Treatment with HDAC inhibitors or introduction of exogenous Brm into Brm-deficient cell lines significantly reduced the oncogenic potential as assessed by colony-forming activity in soft agar or invasion into collagen gel, indicating that, like BRG1, Brm is involved in tumor suppression.
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PMID:The Brm gene suppressed at the post-transcriptional level in various human cell lines is inducible by transient HDAC inhibitor treatment, which exhibits antioncogenic potential. 1600 16

Interactions between the histone deacetylase inhibitor SAHA and the pharmacologic MEK1/2 inhibitor PD184352 were examined in Bcr/Abl+ human leukemia cells. Coadministration of minimally toxic concentrations of SAHA (or sodium butyrate) and PD184352 (or U0126) resulted in a synergistic increase in mitochondrial damage, caspase activation, and apoptosis in K562 and LAMA 84 cells. Similar interactions were observed in CD34+ cells from two patients with CML and in imatinib mesylate-resistant K562 cells but not in normal human CD34+ bone marrow cells. These events were associated with a marked increase in ROS generation, inactivation of ERK and Akt, downregulation of p21CIP1, Bcr/Abl, and cyclin D1, and activation of JNK. Of these events, ROS generation, ERK inactivation, and cytochrome c/AIF release were largely caspase-independent, whereas the other phenomena displayed varying degrees of caspase-dependence. Using pharmacologic and genetic approaches, generation of ROS, p21CIP1 downregulation, and inactivation of Akt and MEK were found to play significant functional roles in SAHA/PD184352-mediated lethality, whereas JNK activation and Raf-1 downregulation were determined to represent secondary events. These findings indicate that interruption of the MEK/ERK pathway substantially lowers the threshold for HDAC inhibitor-mediated oxidative injury, mitochondrial dysfunction, and apoptosis, suggesting that this approach warrants further examination in Bcr/Abl+-related malignancies.
Leukemia 2005 Sep
PMID:Synergistic interactions between MEK1/2 and histone deacetylase inhibitors in BCR/ABL+ human leukemia cells. 2773 68

Histone deacetylase inhibitors (HDIs) are a new class of drugs with significant antileukemic activity. To explore mechanisms of disease-specific HDI activity in acute myeloid leukaemia (AML), we have characterised expression of all 18 members of the histone deacetylase family in primary AML blasts and in four control cell types, namely CD34+ progenitors from umbilical cord, either quiescent or cycling (post-culture), cycling CD34+ progenitors from GCSF-stimulated adult donors and peripheral blood mononuclear cells. Only SIRT1 was consistently overexpressed (>2 fold) in AML samples compared with all controls, while HDAC6 was overexpressed relative to adult, but not neo-natal cells. HDAC5 and SIRT4 were consistently underexpressed. AML blasts and cell lines, exposed to HDIs in culture, showed both histone hyperacetylation and, unexpectedly, specific hypermethylation of H3 lysine 4. Such treatment also modulated the pattern of HDAC expression, with strong induction of HDAC11 in all myeloid cells tested and with all inhibitors (valproate, butyrate, TSA, SAHA), and lesser, more selective, induction of HDAC9 and SIRT4. The distinct pattern of HDAC expression in AML and its response to HDIs is of relevance to the development of HDI-based therapeutic strategies and may contribute to observed patterns of clinical response and development of drug resistance.
Leukemia 2005 Oct
PMID:Histone deacetylases in acute myeloid leukaemia show a distinctive pattern of expression that changes selectively in response to deacetylase inhibitors. 1612 Dec 16

Starting from the pharmacophore model for HDAC inhibitor design, a novel series of hydroxamates bearing a uracil moiety as connecting unit (CU) has been prepared and tested. Almost all compounds exhibited HDAC inhibiting activity at low nanomolar concentrations, the N-hydroxy-6-(3,4-dihydro-4-oxo-6-benzyl- and -6-phenyl-2-pyrimidinylthio)hexanamides 1d and 1l being more potent than SAHA in enzymatic assays. Such compounds also caused hyperacetylation in NIH3T3 cell core histones and were endowed with interesting antiproliferative and cytodifferentiating effects in human leukemia (HL-60) cells.
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PMID:Exploring the connection unit in the HDAC inhibitor pharmacophore model: novel uracil-based hydroxamates. 1616 53

The reversible acetylation of histones is critical for regulation of eukaryotic gene expression. The histone deacetylase inhibitors trichostatin (TSA, 1), MS-275 (2) and suberoylanilide hydroxamic acid (SAHA, 3) arrest growth in transformed cells and in human tumor xenografts. However, 1-3 suffer from lack of specificity among the various HDAC isoforms, prompting us to design and synthesize polyaminohydroxamic acid (PAHA) derivatives 6-21. We felt that PAHAs would be selectively directed to chromatin and associated histones by the positively charged polyamine side chain. At 1 microM, compounds 12, 15 and 20 inhibited HDAC by 74.86, 59.99 and 73.85%, respectively. Although 20 was a less potent HDAC inhibitor than 1, it was more potent than 2, more effective as an initiator of histone hyperacetylation, and significantly more effective than 2 at re-expressing p21Waf1 in ML-1 leukemia cells. On the basis of these results, PAHAs 6-21 represent an important new chemical class of HDAC inhibitors.
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PMID:Alkyl-substituted polyaminohydroxamic acids: a novel class of targeted histone deacetylase inhibitors. 1619 Jul 61

To investigate the potential role and the mechanism of PLZF-RARalpha/RARalpha-PLZF double fusion gene in the pathogenesis of acute promyelocytic leukemia (APL) in vivo at systematic biological level, PLZF-RARalpha/RARalpha-PLZF double transgenic mouse model was established by intercross; the integration and expression of fusion genes were analyzed by PCR and RT-PCR; the disease phenotype was detected by morphological and pathological examination of peripheral blood and bone marrow cells, as well as flow cytometry assays; the effects of ATRA with or without tricostatin A on bone marrow blast cells from PLZF-RARalpha/RARalpha-PLZF double TM were observed. The results showed that leukemia occurred in 5 PLZF-RARalpha/RARalpha-PLZF double TM 7, 7, 9, 11 and 11 months respectively, out of them two (40%) with classic APL features, the others (60%) with chronic myeloid leukemia through an observation period of 18 months. The leukemia occurrence of PLZF-RARalpha/RARalpha-PLZF TM was about 10%, which was similar to PLZF-RARalpha TM as that reported before. The latency was over 6 months, not earlier than PLZF-RARalpha TM only. No morphologic changes of PLZF-RARalpha/RARalpha-PLZF double TM blast cells to ATRA were observed, but increased cytoplasmic-nuclear ratio and nuclear condensation in bone marrow blast cells were found in combination of ATRA with tricostatin A. It is concluded that PLZF-RARalpha/RARalpha-PLZF double fusion gene transgenic mice have heterogeneity of pathogenesis. HDAC inhibitors such as trichostatin A, in combination with ATRA, induce differentiation of the blast/promyelocytic cells from PLZF-RARa/RARa-PLZF double TM, but not ATRA alone.
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PMID:[hCG-PLZF-RARalpha/hCG-RARalpha-PLZF transgenic mice developing into leukemia]. 1640 52

Valproic acid (VPA), a histone deacetylase inhibitor, causes differentiation in different cell lines and in a cell-specific manner; yet, its effect on megakaryocytic (MK) differentiation has not been studied. We evaluated whether VPA induces MK differentiation in a UT-7 cell line through histone acetylation in the GpIIIa gene region and activation of the ERK pathway. UT-7 cells, derived from megakaryoblastic leukemia, were treated with VPA at various concentrations, and the expression of differentiation markers as well as the gene expression profile was assessed. Flow cytometry, immunoblot analysis, and RT-PCR demonstrated that VPA induced the expression of the early MK markers GpIIIa (CD61) and GpIIb/IIIa (CD41) in a dose-dependent manner. The VPA-treated cells showed hyperacetylation of the histones H3 and H4; in particular, histone acetylation was found to have been associated with CD61 expression, in that the GpIIIa promoter showed H4 hyperacetylation, as demonstrated by the chromatin immunoprecipitation assay. Furthermore, activation of the ERK pathway was involved in VPA-mediated CD61/CD41 expression and in cell adhesion, as demonstrated by using the MEK/ERK inhibitor U0126. In conclusion, the capacity of VPA to commit UT-7 cells to MK differentiation is mediated by its inhibitory action on HDAC and the long-lived activation of ERK1/2.
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PMID:HDAC inhibition is associated to valproic acid induction of early megakaryocytic markers. 1673 51

B-cell chronic lymphocytic leukaemia (B-CLL) cells fail to undergo apoptosis. The mechanism underlying this resistance to cell death is still largely unknown. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) effectively kills tumour cells but not normal cells, and thus represents an attractive tool for the treatment of cancer. Unfortunately, lymphocytes from B-CLL patients are resistant to TRAIL-mediated apoptosis. Thus, we aimed to study the involvement of PED, a DED-family member with a broad antiapoptotic action, in this resistance. We demonstrate that B lymphocytes obtained from patients with B-CLL express high levels of PED. Treatment of B-CLL cells with specific PED antisense oligonucleotides, a protein synthesis inhibitor or HDAC inhibitors, induced a significant downregulation of PED and sensitized these cells to TRAIL-induced cell death. These findings suggest a direct involvement of PED in resistance to TRAIL-induced apoptosis in B-CLL. It also identifies this DED-family member as a potential therapeutic target for this form of leukaemia.
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PMID:Selective inhibition of PED protein expression sensitizes B-cell chronic lymphocytic leukaemia cells to TRAIL-induced apoptosis. 3061 Jul 45

The last decade has witnessed the introduction of a large number of novel, molecularly targeted agents into the therapeutic armamentarium against diverse forms of cancer, including leukemia. Such agents include signal transduction, cell cycle, histone deacetylase, Hsp90, proteasome, and Bcl-2 family member inhibitors, among others. While most of these agents have been or are currently being evaluated in adult patients with acute leukemia, experience in childhood leukemia is very limited. Although the use of such targeted agents as potentiators of conventional cytotoxic agent activity represents a logical approach, an emerging body of evidence suggests that neoplastic cells in general, and leukemic cells in particular, are highly susceptible to a therapeutic strategy in which survival signaling and cell cycle regulatory pathways are simultaneously disrupted. In in vitro studies, highly synergistic antileukemic interactions have been reported between CDK and HDAC inhibitors; HDAC and proteasome inhibitors; Bcl-2 antagonists and CDK inhibitors; MEK/ERK and Chk1 inhibitors, and proteasome and CDK inhibitors, among other combinations. Some of these strategies, including combinations of HDAC and CDK inhibitors, and CDK and proteasome inhibitors, have now entered the clinical arena in patients with leukemia and other hematologic malignancies. Based upon preclinical results to date, there is reason to suspect that such strategies might prove to be active against several types of childhood leukemia. Thus, over the next decade, the introduction of molecularly targeted agents, alone and in combination, into the therapeutic armamentarium against childhood leukemia may have significant implications for children with this disease.
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PMID:Simultaneous interruption of signal transduction and cell cycle regulatory pathways: implications for new approaches to the treatment of childhood leukemias. 1758 30

By associating with cyclic AMP-responsive element-binding protein (CREB), the human T-cell leukemia virus type 1 (HTLV-1) Tax protein activates transcription from the HTLV-1 long terminal repeat (LTR), which contains multiple cyclic AMP-responsive elements. The transducers of regulated CREB activity (TORCs) were a recently identified family of CREB co-activators that bind to CREB to enhance CRE-mediated transcription. TORC3, a TORC family protein, dramatically enhances Tax-mediated transcription from the LTR. In this study, we performed a yeast two-hybrid screen using the N-terminal region of TORC3 as bait and identified B-cell chronic lymphatic leukemia protein 3 (BCL3) as a protein interacting with TORC3. This interaction was confirmed by glutathione S-transferase pulldown assays and co-immunoprecipitation experiments with detection by Western blotting. The ankyrin repeat domain of BCL3 interacted with TORC3. By using a luciferase assay, we determined that BCL3 inhibited transcription from the HTLV-1 LTR in a manner dependent on TORC3. Knockdown of endogenous BCL3 using RNA interference enhanced transcriptional activation of CRE. Treatment with trichostatin A, a potent inhibitor of the transcriptional co-repressor HDAC, partially reversed the inhibitory effect of BCL3. These results suggest that BCL3 functions as a repressor of HTLV-1 LTR-mediated transcription through interactions with TORC3. In addition to stimulating transcription from the HTLV-1 LTR, Tax also enhances BCL3 expression; thus, transcription from the LTR is regulated by both positive and negative feedback mechanisms.
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PMID:BCL3 acts as a negative regulator of transcription from the human T-cell leukemia virus type 1 long terminal repeat through interactions with TORC3. 1764 18


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