The Synergistic Effect of DNA Methylation Inhibitor 5-Azacytidine and Bcl-2 Signaling Blockade ABT-737 Combination Treatment Induce Apoptosis In AML

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3311-3311
Author(s):  
Yuexi Shi ◽  
Twee Tsao ◽  
Hongbo Lu ◽  
Sergej Konoplev ◽  
Wendy D. Schober ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Death ◽  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Cytotoxic Agents ◽  
Leukemia Cells ◽  
Clinical Activity ◽  
Acute Myeloid

Abstract Abstract 3311 Bcl-2 family proteins are key regulators of apoptosis. Aberrations in Bcl2 levels are known to promote tumorigenesis and chemoresistance. Thus strategies to target Bcl2 will likely provide effective therapies for malignancies such as acute myeloid leukemia (AML). ABT-737 is a small molecule BH3 mimetic that binds tightly to a hydrophobic cleft on Bcl-2 and Bcl-XL and exerts its proapoptotic function by preventing antiapoptotic Bcl-2 family members from sequestering activating BH3 proteins (Oltersdorf et al., Nature 2005). We have reported that ABT-737 effectively kills acute myeloid leukemia blast, progenitor, and stem cells without affecting normal hematopoietic cells. ABT-737 induces the disruption of the BCL-2/BAX complex and BAK-dependent but BIM-independent activation of the intrinsic apoptotic pathway (Konopleva et al., Cancer Cell 2006). The ABT-737 related clinical compound, ABT-263, is undergoing Phase I/II studies in chronic lymphocytic leukemia, with initial signs of clinical activity. However, the main side effect is thrombocytopenia resulting from inhibition of Bcl-XL. Hence, combinations of ABT-737 with non-cytotoxic agents are desirable to take full advantage of ABT236's unique spectrum of biophysical and preclinical activities. In this project, we studied pharmacologic interactions between ABT-737 and the DNA methyltransferase inhibitor 5-azacytidine (5-azaC). 5-azaC is a cytidine analog with clinical activity in myelodysplastic syndromes (MDS) and in AML. Since recent studies indicate that 5-azaC induce DNA damage in p53-dependent fashion, we tested the hypothesis that the pro-apoptotic effects of 5-azaC/ABT-737 combination are related to non-redundant activation of BH3-only proteins and mitochondrial apoptosis in AML cells with wt p53. In vitro, 5-azaC and ABT-737 in combination for 72 hrs induced growth inhibition and apoptosis in AML cell lines OCI-AML3, MOLM-13 and U937 in a highly synergistic, dose-dependent fashion, with combination indices (CIs) ranging from 0.1 to 0.22. These effects were observed even at low concentrations (5-azaC 100nM and ABT-737 10nM, at 10:1 ratio). In contrast, no synergistic apoptosis was seen in p53-null HL-60 cells. Likewise, ABT-737/5-azaC induced apoptosis in a synergistic fashion in OCI-AML3 cells infected with vector control shRNA (CI=0.04) but failed to induce cell death in OCI-AML3 p53 shRNA cells, indicating critical p53-dependent mechanisms of cell death. In primary AML samples sensitive to ABT-737 alone (n=3), synergistic and additive effects were seen. The combined effects of 5-azaC and ABT-737 were further investigated in NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ mice injected with cells from a patient with primary refractory AML. Seven days after leukemia transplantation, mice were treated with vehicle, ABT-737 (intraperitoneally (IP), 75mg/kg/day for 10 days), 5-azacytidine (IP, 4mg/kg/day for 5 days) or with the combination. Engraftment of patient leukemia cells was analyzed by the immunohistochemical detection of CD45-positive cells in bone marrow and spleen seven weeks after transplantation. Both, ABT-737 and 5azaC each exerted anti-leukemic effects, as evidenced by significant reduction in leukemia cells in bone marrow and spleen (10% and 3% CD45+ cells detectable in 1/3 mice in ABT-737 and 5-azaC groups, respectively), no CD45+ AML cells were detected in organs of 3/3 mice treated with the combination. No overt hemorrhage was detected in the animals. In summary, the combination of 5-azaC and ABT-737 induces synergistic cells death in AML cell lines and in a subset of primary AML samples in a p53-dependent fashion. The mechanisms of this pharmacologic interactions including the p53-dependent upregulation of BH3-only proteins, described by us for ABT-737/MDM2 inhibitor combinations, are currently under investigation. Results suggest that this therapeutic strategy can be successfully utilized in AML patients with low mutation rate and unimpaired signaling of p53. Disclosures: No relevant conflicts of interest to declare.

Activities and Mechanism Based Combinations Of Omacetaxine In Acute Myeloid Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1288-1288
Author(s):  
Rong Chen ◽  
Bonnie Leung ◽  
Yuling Chen ◽  
William Plunkett
Keyword(s):  
Acute Myeloid Leukemia ◽  
Protein Synthesis ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Lymphocytic Leukemia ◽  
Leukemia Cells ◽  
Bh3 Mimetics ◽  
Abl Kinase ◽  
Acute Myeloid

Abstract Omacetaxine, an inhibitor of translation, was recently granted accelerated approval for the treatment of chronic myeloid leukemia (CML). Omacetaxine blocks translation elongation by competing with the incoming aminoacyl-tRNAs for binding to the A-site cleft in the peptidyl-transferase center. Our previous studies showed that by transiently inhibiting translation, omacetaxine reduced the expression of the key, short-lived oncoproteins Bcr/Abl and Mcl-1, leading to cell death in the CML cells. This action sensitized the cells to the Abl kinase inhibitor and killed the CML cells synergistically. Further, as omacetaxine acts in a different mechanism than the Abl kinase inhibitors, it overcame resistance to TKI that was associated with kinase domain mutations. These studies paved the foundation for the clinical development of omacetaxine in CML. We also demonstrated that omacetaxine was active in chronic lymphocytic leukemia by translational inhibition of Mcl-1 expression. In contrast to normal tissues, the fact that the leukemia cells are critically dependent on the oncogene activity for survival provided a biologic context for a positive therapeutic index. As the biological features of acute myeloid leukemia (AML) rely largely on the overexpressed oncoproteins or constitutively activated kinases, we hypothesized that omacetaxine would have therapeutic benefit in AML either alone or in mechanism based combinations. To test this hypothesis, first, we compared omacetaxine to AC220, a potent FLT3 inhibitor, in AML cell lines OCI-AML3 and MV4-11. OCI-AML3 cells harbor the signature mutation of NPM1, whereas MV4-11 is a widely used model for the internal tandem duplications of FLT3 (FLT3-ITD), a common FLT3 mutation that constitutively activates the receptor tyrosine kinase. AC220 was selectively toxic to the MV4-11 cells, but had no effect on the viability of OCI-AML3. This is consistent with the biological context of MV4-11, but not OCI-AML3, that is addicted to the sustained activity of FLT3 for survival. In contrast, omacetaxine induced apoptosis in both cell lines with IC50s less than 100 nM. Protein synthesis was inhibited in both lines, measured by the incorporation of tritiated leucine. Apoptosis was induced rapidly within 24 h by omacetaxine, whereas AC220 required 72 h to kill the leukemia cells. These results indicated a common dependence on the continued protein synthesis in the AML lines, suggesting a potentially broad application of omacetaxine in AML patients with diverse genetic backgrounds. Over-expression of the anti-apoptotic protein Mcl-1 is associated with AML disease maintenance and resistant to therapy. Both Mcl-1 and FLT3 turn-over rapidly and are vulnerable targets of transient translation inhibition. Immunoblots showed that omacetaxine reduced the levels of both FLT3 and Mcl-1 in the MV4-11 cells. This activity augmented the effect of AC220 on FLT3 kinase, and induced synergistic apoptosis. Same synergistic combination was observed with omacetaxine and sunitinib, an inhibitor of FLT3, KIT and PDGF-R. Dose reduction index derived from these analyses showed that omacetaxine greatly potentiated the activity of both AC220 and sunitinib, resulting in profound apoptosis. Both Bcl-2 and Mcl-1 are pro-survival proteins that regulate apoptosis by interacting with the BH3 motifs of their pro-apoptotic partners. BH3 mimetics, such as ABT-199, bind with high affinity to Bcl-2 and block this interaction, but not to Mcl-1. Resistance to BH3 mimetics in AML cells is associated with upregulation of Mcl-1. Since ABT-199 inhibits Bcl-2 but spares Mcl-1, and omacetaxine reduces Mcl-1 without affecting Bcl-2 expression, we hypothesized that their combination would target the two parallel arms of apoptosis control and kill the AML cells synergistically. Indeed, omacetaxine reduced Mcl-1 in the OCI-AML3 cells, leading to loss of mitochondrial membrane potential and apoptosis. ABT-199 blocked Bcl-2 function and also induced the intrinsic pathway of apoptosis. Their combination induced greater mitochondrial damage and apoptosis than either drug alone. The median effect analysis showed that they potentiate each other and exhibited strong synergy. Taken together, these results demonstrated that omacetaxine is active in AML cells alone and in mechanism based combinations. These actions provide rationale that warrants investigation in the clinic. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Acute Myeloid Leukemia-Derived Exosomes Transform Bone Marrow Niche into Leukemic Niche.

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 352-352
Author(s):  
Bijender Kumar ◽  
Mayra Garcia ◽  
Lihong Weng ◽  
Xiaoman Lewis ◽  
Jodi Murakami ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Bone Marrow Niche ◽  
Stromal Compartment ◽  
Bm Niche ◽  
Acute Myeloid

Abstract Increasing evidence suggests that leukemia cells take shelter in the bone marrow (BM) niche, where they hide from chemotherapy and continue to divide. As yet, how leukemia cells alter the BM niche to facilitate their growth and assist them in evading chemotherapy is unclear. In this study, we provide compelling evidences that acute myeloid leukemia (AML), through exosome secretion, transformed the BM niche to facilitate their own growth and suppress normal hematopoiesis. Using AML xenograft and MLL-AF9 knock-in mouse model, we show that leukemia cells as well as AML-derived exosomes stimulate the growth of BM stromal progenitors and blocked the osteolineage development in our stromal compartment analysis. Histological analysis and micro-CT examination confirmed loss or thinning of the bone in both leukemia and leukemic exosome-treated animals. Expression of cell adhesion molecules (NCAM1, VCAM1, CD44, OPN & ICAM1) and factors important for angiogenesis (Angpt1, Angpt2 and VEGF) are upregulated, whereas genes important for HSC maintenance (CXCL12 and SCF), osteoblast (OCN, OSX, Notch3 and IGF1) and chondrocyte (ACAN, SOX9) development are suppressed. While we observed increases in phenotypic LT-HSC in AML-derived exosomes treated mice, these mice show reduced multilineage reconstitution ability, increased cell cycle entry and higher sensitivity to myeloablative stress suggesting that HSCs from exosome-treated mice have lower stem cell activity than their counterparts from normal mice.In addition, leukemia-modified stroma cells exhibit marked reduction in ability to support normal HSCs. Pre-treatment of AML-derived exosome “prime” the animal for leukemia cell invasion and accelerate leukemia progression. Conversely,disruption of exosome secretion by targeting Rab27a in AML cells significantly delays leukemia progression. These data strongly support the notion that leukemia-modified niches favor leukemic cell proliferation and suppress normal hematopoiesis. Disclosures No relevant conflicts of interest to declare.

Autophagy Inhibition Overcomes Resistance to Cytosine Arabinoside in Acute Myeloid Leukemia Cells through Inducing Autophagic Cell Death and Intrinsic Pathway Apoptosis

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 909-909
Author(s):  
Yundeok Kim ◽  
Ju-In Eom ◽  
Hoi-Kyung Jeung ◽  
Jieun Jang ◽  
Jin Seok Kim ◽  
...  
Keyword(s):  
Cell Death ◽  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Cytosine Arabinoside ◽  
Myeloid Leukemia ◽  
Beclin 1 ◽  
Leukemia Cells ◽  
Intrinsic Pathway ◽  
Acute Myeloid Leukemia Cells ◽  
Acute Myeloid

Abstract Background A major obstacle to the successful treatment of acute myeloid leukemia (AML) is the development of chemoresistance. Identifying the novel agents overcoming drug resistance is critical for improving AML outcomes. Autophagy is an indispensable lysosomal self-digestion process involved in the degradation of aggregated proteins and damaged organelles. Autophagy has recently been demonstrated as important for conferring resistance to chemotherapy and targeted therapy. The antimalarial drug hydroxychloroquine (HCQ) is able to inhibit autophagy and therefore is being considered for cancer therapeutics. However, the effects of HCQ on chemoresistant myeloid leukemia cells have not been investigated. Objective The present study was designed to examine comparatively the effects of HCQ on the induction of cell death of the chemosensitive and chemoresistant acute myeloid leukemia cells, and elucidate its detailed mechanism. Method Ara-C (Cytosine arabinoside)-sensitive (U937, AML-2) and Ara-C-resistant (U937/AR, AML-2/AR) human myeloid leukemia cell lines were used to evaluate HCQ-induced cytotoxicity, autophagy, and apoptosis, as well as effects on cell death-related signaling pathways. Result U937/AR cell line showed a significantly higher number of autophagic vesicles and higher level of autophagic proteins. We initially found that HCQ caused dose- and time-dependent cell death of myeloid leukemia cells evaluated. HCQ-induced cell death rate was significantly higher in the chemoresistant U937/AR, AML-2/AR compared to chemosensitive U937 and AML-2 cells, respectively. Particularly, in Ara-C-resistant cell lines, HCQ triggers the activation of autophagy based on the results of increased number of autophagosomes, conversion of microtubule-associated protein light chain 3 (LC3)-I to LC3-II, and formation of GFP-LC3-positive punta. However, p62/SQSTM1 level was increased, suggesting that HCQ blocks the degradation of p62/SQSTM1 and autophagy flux. Modest upregulation of beclin-1 and Atg7 (autophagy-related protein 7) was observed. With continued exposure to HCQ, LC3 conversion was followed by nuclear condensation, procaspase-3 and -9 activation, release of cytosolic cytochrome C, and decreased mitochondrial membrane potential, indicating apoptosis via a mitochondria-dependent pathway. Pretreatment of leukemia cells with the autophagy blocker 3-methyladenine or siRNAs against beclin-1 or p62/SQSTM1, reduced HCQ-induced cell death, LC3 conversion, and procaspase-9 cleavage. The pan-caspase inhibitor z-VAD-fmk and the caspase-9 inhibitor z-LEHD-fmk, but not the caspase-8 inhibitor z-IETD-fmk, reduced HCQ-mediated cell death and caspase activation. However, LC3 conversion was unaffected. Additionally, Ara-C and HCQ synergistically induced cell death in U937/AR cells. Conclusion Taken together, our data show that HCQ effectively induced cell death in Ara-C-resistant AML cells through activation of autophagy and subsequent intrinsic pathway apoptosis. Our findings suggest HCQ might improve the therapeutic outcome in chemoresistant AML. Disclosures No relevant conflicts of interest to declare.

Dendrogenin_A : A Natural Liver X Receptor Modulator for the Treatment of Acute Myeloid Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3767-3767
Author(s):  
Christian Recher ◽  
Marion David ◽  
Philippe de Medina ◽  
Cécile Bize ◽  
Nizar Serhan ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Death ◽  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Equity Ownership ◽  
Kg1 Cells ◽  
Acute Myeloid

Abstract Acute Myeloid Leukemia (AML) is the most common type of leukemia in adults. Despite intensive research, current treatments remain unsatisfactory with only 40% of younger (<60 years) and less than 10% of older (>60 years) AML patients achieving long-term complete remission. Consequently, drugs with novel mechanism of action are urgently needed to improve the outcome of these patients. We have recently identified Dendrogenin A (DDA) as a cholesterol metabolite present in normal cells but undetectable in various cancer cell lines including AML (de Medina et al, Nat Commun, 2013). DDA, the first steroidal alkaloid identified in mammals, exhibited strong anticancer effects against different tumor models in vitro and in vivo. In this study, we investigated the antileukemic potency of DDA in AML. We demonstrated that DDA exerts potent cytotoxic effect in a large panel of AML cell lines and cytogenetically and molecularly diverse primary AML patient samples (n=50) with a median IC50 of 3.3 µM (range 1.2-10 µM). We determined that DDA triggers both apoptosis and cytotoxic autophagy on AML cells. Macroautophagy was characterized by the accumulation of autophagic vacuoles and the stimulation of autophagic flux. As opposed to conventional chemotherapies, the antileukemic effect of DDA was similarly efficient in both immature stem/progenitor CD34+CD38-CD123+ subpopulation and leukemic bulk. Interestingly, the antileukemic activity of DDA on AML patient samples was not correlated to usual prognostic factors such as adverse cytogenetic risk karyotype, clonogenic ability, white blood cells count and FLT3-ITD or NPM status. Pharmacokinetic studies revealed that both per os (PO) and intraperitoneal (IP) administration led to a good absorption with calculated bioavailability of 74% (PO) and 48% (IP), showing that these modes of administration are relevant to in vivo preclinical studies. We then examined the in vivo anti-leukemic efficacy of DDA in NOD/SCID mice injected subcutaneously with HL60 and KG1 cells. We demonstrated that daily administration of DDA (20 mg/kg IP or 40 mg/kg PO) significantly reduced KG1 and HL60 tumor growth. Immunohistochemical analysis revealed that AML xenografts from mice exposed to DDA display a 3.5 fold increase of LC3 punctated cells and a decreased P62 level highlighting that DDA induces autophagy in vivo. Furthermore, DDA significantly kills AML cells in bone marrow and brain (55±5.6% reduction of viable CD45+ cells), and strongly reduces (57±7.8%) the total cell tumor burden in bone marrow and spleen in established disease models (eg. orthotopically engraftment of HL60 cells and three primary AML patient cells via tail vein injection in NOD/SCID/IL2Rγc-deficient mice). In addition, we showed that DDA is well tolerated in mice at effective dose and spares normal hematopoietic stem/progenitor cells from healthy donor. Mechanistic studies revealed that DDA is a natural modulator of the Liver X Receptor (LXR), a nuclear receptor involved in cholesterol homeostasis, immunity and proliferation. We found that the silencing of LXRβ gene prevents the capacity of DDA to trigger both cell death and autophagy on AML cells in vitro. In addition, DDA failed to block tumor development and to trigger autophagy on LXRβ-invalidated KG1 cells xenografted on NOD/SCID mice. Moreover, DDA strongly stimulates the expression of the myeloid leukemogenesis tumor suppressors Nur77 and Nor1 through an LXRβ-dependent mechanism. Interestingly, DDA triggers the relocation of Nur77 to the mitochondria, a process associated with both apoptosis and autophagic cell death. This study provides a strong rationale to bring DDA in clinical trials for patients with AML. Disclosures de Medina: Affichem: Employment. Bize:Affichem: Employment. Paillasse:Affichem: Employment. Noguer:Affichem: Employment. Sarry:Affichem: Equity Ownership. Silvente-Poirot:Affichem: Equity Ownership. Poirot:Affichem: Equity Ownership.

scholarly journals Microrna-494 Activation Suppresses Bone Marrow Stromal Cell-Mediated Drug Resistance in Acute Myeloid Leukemia Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1576-1576
Author(s):  
Chen Tian ◽  
Guoguang Zheng ◽  
M. James You ◽  
Yizhuo Zhang
Keyword(s):  
Bone Marrow ◽  
Drug Resistance ◽  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Tumor Formation ◽  
Cell Counts ◽  
Coculture System ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is not sensitive to chemotherapy partially because of the protection of AML cells by mesenchymal stromal cells (MSCs). Our previous studies found that MSCs protected AML cells from apoptosis through the c-Myc-dependent pathway. However, the mechanism by which MSCs regulate c-Myc in AML cells is still unknown. To elucidate the mechanism, we performed microRNA array analysis of AML cell lines and validated by TaqMan realtime PCR. The results showed that the expression of microRNA-494 (miR-494) in AML cells after coculture with MSCs was down-regulated. Reporter gene analysis confirmed miR-494 as one of the regulators of c-Myc. In the coculture system, activation of miR-494 in AML cells suppressed proliferation and induced apoptosis of AML cells in vitro. After addition of mitoxantrone to the coculture system, the proliferation of AML cells with miR-494 activation was suppressed more than that of control cells. After subcutaneous injection of AML cell lines in combination with MSC, tumor growth was suppressed in mice injected with miR-494-overexpressing AML cells. The rate of tumor formation was even lower after mitoxantrone treatment in the miR-494 overexpressing group. Moreover, miR-494 activation resulted in a decrease of leukemic cell counts in peripheral blood and bone marrow and prolonged survival in mice injected with miR-494-overexpressing AML cellls and MSCs compared to the control mice. Our results indicate that miR-494 suppresses drug resistance in AML cells by down-regulating c-Myc through interaction with MSCs and that miR-494 therefore is a potential therapeutic target. Disclosures No relevant conflicts of interest to declare.

Antitumor Effect of Pomolic Acid in Acute Myeloid Leukemia Cells Involves Cell Death, Decreased Cell Growth and Topoisomerases Inhibition

2019 ◽  
Vol 18 (10) ◽  
pp. 1457-1468
Author(s):  
Michelle X.G. Pereira ◽  
Amanda S.O. Hammes ◽  
Flavia C. Vasconcelos ◽  
Aline R. Pozzo ◽  
Thaís H. Pereira ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Natural Compound ◽  
Dna Topoisomerases ◽  
Human Dna ◽  
Pomolic Acid ◽  
Acute Myeloid

Background: Acute myeloid leukemia (AML) represents the largest number of annual deaths from hematologic malignancy. In the United States, it was estimated that 21.380 individuals would be diagnosed with AML and 49.5% of patients would die in 2017. Therefore, the search for novel compounds capable of increasing the overall survival rate to the treatment of AML cells is urgent. Objectives: To investigate the cytotoxicity effect of the natural compound pomolic acid (PA) and to explore the mechanism of action of PA in AML cell lines with different phenotypes. Methods: Three different AML cell lines, HL60, U937 and Kasumi-1 cells with different mechanisms of resistance were used to analyze the effect of PA on the cell cycle progression, on DNA intercalation and on human DNA topoisomerases (hTopo I and IIα) in vitro studies. Theoretical experiments of the inhibition of hTopo I and IIα were done to explore the binding modes of PA. Results: PA reduced cell viability, induced cell death, increased sub-G0/G1 accumulation and activated caspases pathway in all cell lines, altered the cell cycle distribution and inhibited the catalytic activity of both human DNA topoisomerases. Conclusion: Finally, this study showed that PA has powerful antitumor activity against AML cells, suggesting that this natural compound might be a potent antineoplastic agent to improve the treatment scheme of this neoplasm.

scholarly journals SETDB1 mediated histone H3 lysine 9 methylation suppresses MLL-fusion target expression and leukemic transformation

Haematologica ◽  
2019 ◽  
Vol 105 (9) ◽  
pp. 2273-2285 ◽  
Author(s):  
James Ropa ◽  
Nirmalya Saha ◽  
Hsiangyu Hu ◽  
Luke F. Peterson ◽  
Moshe Talpaz ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Critical Role ◽  
High Expression ◽  
Leukemia Cells ◽  
Biological Impact ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Epigenetic regulators play a critical role in normal and malignant hematopoiesis. Deregulation, including epigenetic deregulation, of the HOXA gene cluster drives transformation of about 50% of acute myeloid leukemia. We recently showed that the Histone 3 Lysine 9 methyltransferase SETDB1 negatively regulates the expression of the pro-leukemic genes Hoxa9 and its cofactor Meis1 through deposition of promoter H3K9 trimethylation in MLL-AF9 leukemia cells. Here, we investigated the biological impact of altered SETDB1 expression and changes in H3K9 methylation on acute myeloid leukemia. We demonstrate that SETDB1 expression is correlated to disease status and overall survival in acute myeloid leukemia patients. We recapitulated these findings in mice, where high expression of SETDB1 delayed MLL-AF9 mediated disease progression by promoting differentiation of leukemia cells. We also explored the biological impact of treating normal and malignant hematopoietic cells with an H3K9 methyltransferase inhibitor, UNC0638. While myeloid leukemia cells demonstrate cytotoxicity to UNC0638 treatment, normal bone marrow cells exhibit an expansion of cKit+ hematopoietic stem and progenitor cells. Consistent with these data, we show that bone marrow treated with UNC0638 is more amenable to transformation by MLL-AF9. Next generation sequencing of leukemia cells shows that high expression of SETDB1 induces repressive changes to the promoter epigenome and downregulation of genes linked with acute myeloid leukemia, including Dock1 and the MLL-AF9 target genes Hoxa9, Six1, and others. These data reveal novel targets of SETDB1 in leukemia that point to a role for SETDB1 in negatively regulating pro-leukemic target genes and suppressing acute myeloid leukemia.

scholarly journals High-dose mitoxantrone induces programmed cell death or apoptosis in human myeloid leukemia cells

Blood ◽  
1993 ◽  
Vol 82 (10) ◽  
pp. 3133-3140 ◽  
Author(s):  
K Bhalla ◽  
AM Ibrado ◽  
E Tourkina ◽  
C Tang ◽  
S Grant ◽  
...  
Keyword(s):  
Cell Death ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Clonogenic Survival ◽  
Leukemia Cells ◽  
Response Relationship ◽  
Dose Response Relationship ◽  
Kinase C ◽  
Acute Myeloid Leukemia Cells ◽  
Acute Myeloid

Abstract Mitoxantrone has been shown in vitro to exhibit a steep dose-response relationship with respect to the clonogenic survival of acute myeloid leukemia cells. In this report, we show that 1-hour exposure of human myeloid leukemia HL-60 and KG-1 cells to mitoxantrone concentrations ranging between 0.1 and 10.0 mumol/L induced internucleosomal DNA fragmentation of approximately 200-bp integer multiples, characteristic of cells undergoing programmed cell death (PCD) or apoptosis. Mitoxantrone-mediated PCD was associated with a steep inhibition of the clonogenic survival of the leukemic cells. In addition, intracellularly, mitoxantrone-induced PCD was associated with a marked induction of c-jun and significant repression of c-myc and BCL-2 oncogenes. Pretreatment with the protein kinase C stimulator phorbol myristate acetate enhanced mitoxantrone-induced internucleosomal DNA fragmentation, whereas protein kinase C inhibitors staurosporine and H7 had no effect. These findings suggest that PCD is a potential mechanism underlying the steep dose-response relationship of mitoxantrone to the inhibition of clonogenic survival of acute myeloid leukemia cells.

Sign in / Sign up

Export Citation Format

Share Document