scholarly journals Knock-in of Dnmt3a R878H Recapitulates Human Acute Myeloid Leukemia Harboring DNMT3A Mutation and Is Highly Responsive to mTOR Inhibitor Rapamycin

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2836-2836
Author(s):  
Yujun Dai ◽  
Yueying Wang ◽  
Jinyan Huang ◽  
Li Xia ◽  
Xiaodong Shi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Mtor Inhibitor ◽  
Leukemic Cells ◽  
Rna Seq ◽  
Human Acute Myeloid Leukemia ◽  
Acute Myeloid

Abstract Introduction DNMT3A is a gene frequently mutated in human acute myeloid leukemia (AML), with DNMT3A R882H as the hot spot. It had been long postulated that DNMT3A mutation should play a key role in AML pathogenesis, so far the main animal models used were Dnmt3a-/- or transplantation of retrovirally transduced bone marrow cells expressing human DNMT3A R882H mutations (BMT). To recapitulate the features of human AML associated with DNMT3A mutation, this study generated a conditional knock-in mouse model to express Dnmt3a R878H mutation (homologous to human DNMT3A R882H) from the endogenous promoter/enhancer. We investigated epigenetic changes, including gene expression profiles, DNA methylation, and chromatin modification as affected by the mutation. We also explored the potential mechanisms that can explain the process by which DNMT3Amutation hierarchically induces abnormal hematopoiesis and the manner by which specific regulators of relevant pathways in murine and human settings can be targeted for potential therapeutic applications. Method We performed the single-cell RNA-seq (scRNA-seq) of LSKs and MEPs, RNA-seq and Methylated DNA immunoprecipitation sequencing (MeDIP-seq) of Gr-1 cells and whole exome sequence (WES) of BMs and tails in Dnmt3a R878H conditional knock-in mice. Result Approximately 4-6 months after birth with interferon induction, all Dnmt3aR878H/WTMx1-Cre+ knock-in mice developed AML of myelomonocytic subtype, characterized by massive expansion of immature cells and infiltration of bone marrow, spleen and lymph node, along with hyperleukocytosis, thrombocytosis, splenomegaly and lymphadenectasis. The leukemic mice also showed severe diffuse skin ulceration and alopecia. The transcriptome and DNA methylation profiling of bulk Gr-1 leukemic cells and the single-cell RNA-sequencing of LSKs/MEPs revealed significant changes in gene expression and epigenetic regulatory patterns that could cause differentiation arrest and growth advantage. Consistent with leukemic cell accumulation in G2/M phase, CDK1 was found overexpressed as a result of mTOR gene activation due to DNA hypomethylation in the gene body region. We then discovered that overexpressed CDK1 could compete with EZH2 in binding to DNMT3A, induce EZH2 phosphorylation and reduction, and result in abnormal histone methylation. Notably, we showed a very significant response from Dnmt3aR878H/WTto the therapeutic effect of the mTOR inhibitor rapamycin, particularly in terms of prolongation of lifespan in treatment group as compared to the control group (p<0.001). Moreover, rapamycin exerted strong inhibitory effects, including anti-proliferative and apoptosis-induction ones, on human AML cells lines and primary samples from AML patients harboring DNMT3A mutation. Conclusions We established a novel mouse model for the expression of mutant Dnmt3a R878H from endogenous locus to investigate the role of Dnmt3a abnormality in leukemogenesis. Indeed, Dnmt3aR878H/WTMx1-Cre+ mice developed AML of myelomonocytic subtype with skin injury. We discovered unique gene expression and DNA methylation patterns in concordance with enhanced proliferation and suppressed differentiation in leukemic cells. The heterogeneity of gene expression in individual leukemic stem/progenitor cells implied the presence of clonal diversity, which could underlie disease evolution. The activation of mTOR and the resultant overexpression of CDK1 might contribute to malignant transformation. Evidence has been obtained in both murine and human settings to suggest DNMT3A mutation-related AML as a potential disease target for rapamycin. Disclosures No relevant conflicts of interest to declare.

scholarly journals Thyrointegrin αVβ3 Antagonist: Implications in Acute Myeloid Leukemia

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4434-4434
Author(s):  
Noureldien Darwish ◽  
Gennadi V. Glinsky ◽  
Shaker A Mousa
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Anticancer Activity ◽  
Myeloid Leukemia ◽  
Leukemic Cells ◽  
Biological Functions ◽  
Regulated Gene Expression ◽  
Acute Myeloid

Abstract Leukemic cells are able to receive and send several signals within bone marrow niche that play an important role in their survival. One of the important crosstalk is the interaction between the bone marrow microenvironment proteins (vitronectin, fibronectin, fibrinogen, and ostepontin) and thyrointegrin αVβ3 on leukemic cells, generating ligand-specific outside-in signals that are relevant to a variety of cell functions, including gene transcription, cell division, cell attachment, and motility Our previous experiment using in vivo AML animal models with primary AML cells and cell lines have shown significant reduction of leukemic cell burden 74% and &gt;95% (P&lt;0.0001), respectively, after daily subcutaneous treatment with thyrointegrin αvβ3 antagonist fb-PMT (Ki 0.23 nM) at 3 and 10 mg/kg, for 3-4 weeks. In this study we focused on evaluations of the molecular effects of fb-PMT in leukemic cells. Acute myeloid leukemia cell lines (K562-Luc and KG1a cells) were cultured in 50 cm² cell culture flasks with 10 mL phenol red free RPMI media containing 10% fetal bovine albumin. The leukemic cells were treated (at 50% confluence) with 30 µM fb-PMT for 48 hours. Total RNA was immediately isolated from harvested cells using Triazole and used for microarray analysis. Overall, there were 370 significantly down-regulated gene expression records and 273 significantly up-regulated gene expression records, expression of which were changed at least 1.5-fold in fb-PMT-treated human leukemic cells. Significant examples of the fb-PMT-induced gene expression signatures (GES) of pathway's interference include SNAI, MYC, HIF1A, TWIST1, and TFAP2C (P&lt;0.05). Notably, inference of potential contribution to the fb-PMT anticancer activity of the interference with these pathways seems highly congruent with their known biological functions such as cell cycle control (MYC), survival and maintenance of stem cells (HIF1A, TFAP2C), and essential features of the malignant phenotype (TWIST1, SNAI) (Figure 1). Consistently, examples of the fb-PMT-induced GES of transcriptional pathway's activation include RB1, IRF9, MAML1, RAP1A, and GATA4 pathways (P&lt;0.05), known biological functions of which appear highly consistent with the hypothesis that activation of these pathways might contribute to fb-PMT anticancer activity. Finally, we found that fb-PMT interfered with estrogen signaling in human AML cells. The fb-PMT was associated with decreased phosphorylation and nuclear enrichment of Erα (Figure 1). Collectively, our in vivo study and genomic data have shown the key role thyrointegrin αvβ3 in leukemogenesis. The thyrointegrin αvβ3 antagonist fb-PMT demonstrated potent anticancer actions on human AML through the molecular interference mechanism with multiple signaling pathways supporting growth and survival of leukemic cells Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Human acute myeloid leukemia cells bind to bone marrow stroma via a combination of beta-1 and beta-2 integrin mechanisms

Blood ◽  
1993 ◽  
Vol 82 (10) ◽  
pp. 3125-3132 ◽  
Author(s):  
LJ Bendall ◽  
K Kortlepel ◽  
DJ Gottlieb
Keyword(s):  
Bone Marrow ◽  
Extracellular Matrix ◽  
Acute Myeloid Leukemia ◽  
Cell Adhesion ◽  
Myeloid Leukemia ◽  
Extracellular Matrix Proteins ◽  
Matrix Proteins ◽  
Leukemic Cells ◽  
Beta 2 ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) cells respond to exogenous stimulation from myeloid growth factors that may be secreted by cells of the bone marrow (BM) stroma and retained by glycosaminoglycans in the extracellular matrix. We have analyzed the capacity of malignant cells from patients with AML to maintain close proximity to sites of growth factor production and retention by binding to BM stromal elements, including fibroblasts and extracellular matrix proteins. Leukemic cells from all cases of AML adhered to BM fibroblast (BMF) monolayers (mean +/- standard error [SE] percentage binding, 30.9% +/- 2.5%; n = 23) and to fibronectin and laminin (mean +/- SE percentage binding, 28.0% +/- 4.1% [n = 11] and 21.5% +/- 2.3% [n = 8], respectively). Binding to bovine and human collagen type 1, vitronectin, hyaluronic acid, and albumin was minimal. Analysis of binding mechanisms indicated that very late antigen-4 (VLA-4) and VLA-5 were responsible for AML cell binding to fibronectin. Binding to laminin could be inhibited by antibody to the alpha chain of VLA-6. In contrast, AML cell adhesion to BMF monolayers was not impaired by blocking antibodies to either beta 1 or beta 2 integrins used alone, although the combination of anti-CD11/CD18 and anti-VLA-4 inhibited binding in more than 50% of cases. When anti- VLA-5 was added in these cases, mean +/- SE inhibition of binding of 45.5% +/- 9.1% (P < .001) was observed. Binding of AML cells to extracellular matrix proteins fibronectin and laminin is predominantly beta 1-integrin-dependent, but AML cell adhesion to BMF relies on the simultaneous involvement of beta 1 and beta 2 integrins as well as other currently unrecognized ligands.

scholarly journals Acute myeloid leukemia M4 with bone marrow eosinophilia (M4Eo) and inv(16)(p13q22) exhibits a specific immunophenotype with CD2 expression

Blood ◽  
1993 ◽  
Vol 81 (11) ◽  
pp. 3043-3051 ◽  
Author(s):  
HJ Adriaansen ◽  
PA te Boekhorst ◽  
AM Hagemeijer ◽  
CE van der Schoot ◽  
HR Delwel ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Low Frequency ◽  
Leukemic Cell ◽  
Leukemic Cells ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Cell Populations ◽  
Spontaneous Proliferation ◽  
Acute Myeloid

Abstract Extensive immunologic marker analysis was performed to characterize the various leukemic cell populations in eight patients with inv(16)(p13q22) in association with acute myeloid leukemia with abnormal bone marrow eosinophilia (AML-M4Eo). The eight AML cases consisted of heterogeneous cell populations; mainly due to the presence of multiple subpopulations, which varied in size between the patients. However, the immunophenotype of these subpopulations was comparable, independent of their relative sizes. Virtually all AML-M4Eo cells were positive for the pan-myeloid marker CD13. In addition, the AML were partly positive for CD2, CD11b, CD11c, CD14, CD33, CD34, CD36, CDw65, terminal deoxynucleotidyl transferase (TdT), and HLA-DR. Double immunofluorescence stainings demonstrated coexpression of the CD2 antigen and myeloid markers and allowed the recognition of multiple AML subpopulations. The CD2 antigen was expressed by immature AML cells (CD34+, CD14-) and more mature monocytic AML cells (CD34-, CD14+), whereas TdT expression was exclusively found in the CD34+, CD14- cell population. The eight AML-M4Eo cases not only expressed the CD2 antigen, but also its ligand CD58 (leukocyte function antigen-3). Culturing of AML-M4Eo cell samples showed a high spontaneous proliferation in all three patients tested. Addition of a mixture of CD2 antibodies against the T11.1, T11.2, and T11.3 epitopes diminished cell proliferation in two patients with high CD2 expression, but no inhibitory effects were found in the third patient with low frequency and low density of CD2 expression. These results suggest that high expression of the CD2 molecule in AML-M4Eo stimulates proliferation of the leukemic cells, which might explain the high white blood cell count often found in this type of AML.

In vivo administration of vascular endothelial growth factor (VEGF) and its antagonist, soluble neuropilin-1, predicts a role of VEGF in the progression of acute myeloid leukemia in vivo

Blood ◽  
2002 ◽  
Vol 100 (13) ◽  
pp. 4622-4628 ◽  
Author(s):  
Gunter Schuch ◽  
Marcelle Machluf ◽  
Georg Bartsch ◽  
Masashi Nomi ◽  
Henri Richard ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Vascular Endothelial Growth Factor ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Leukemic Cells ◽  
Vascular Endothelial ◽  
Neuropilin 1 ◽  
Endothelial Growth Factor ◽  
Acute Myeloid

Recent findings implied that the progression of hematologic malignancies, like that of solid tumors, is dependent on neovascularization. Recent studies on patients with acute myeloid leukemia (AML) showed increased levels of leukocyte-associated vascular endothelial growth factor (VEGF) and neovascularization of the bone marrow. Murine (32D, M1) and human (HEL, U937, and UKE-1) leukemic cell lines and freshly isolated leukemic cells were analyzed for the expression of VEGF and VEGF receptor mRNA. The expression of VEGF and VEGF receptors KDR and neuropilin-1 (NRP-1) was detected in these cells. In a murine chloroma model, delivery of VEGF165using microencapsulation technology resulted in enhanced tumor growth and vascularization, whereas treatment with a VEGF antagonist soluble NRP-1 (sNRP-1) inhibited tumor angiogenesis and growth. In a systemic leukemia model, survival of mice injected with adenovirus (Ad) encoding for Fc-sNRP-1 (sNRP-1 dimer) was significantly prolonged as compared with mice injected with Ad-LacZ. Further analyses showed a reduction in circulating leukemic cells and infiltration of liver and spleen as well as bone marrow neovascularization and cellularity. Taken together, these results demonstrate that angiogenic factors such as VEGF promote AML progression in vivo. The use of VEGF antagonists as an antiangiogenesis approach offers a potential treatment for AML. Finally, our novel in vivo drug delivery model may be useful for testing the activities of other peptide antiangiogenic factors.

Detection of Nucleophosmin Gene Mutations in Plasma from Patients with Acute Myeloid Leukemia: Clinical Significance and Implications.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2855-2855
Author(s):  
Wanlong Ma ◽  
Xi Zhang ◽  
Iman Jilani ◽  
Farhad Ravandi ◽  
Elihu Estey ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Peripheral Blood ◽  
Myeloid Leukemia ◽  
Gene Mutations ◽  
Leukemic Cells ◽  
Striking Difference ◽  
Plasma Dna ◽  
Npm1 Mutation ◽  
Acute Myeloid

Abstract Nucleotides insertion in the nucleophosphamin (NPM1) gene has been reported in about one third of patients with acute myeloid leukemia (AML). Multiple studies showed that the presence of NPM1 mutations associated with better outcome in patients with AML. Studies reported to date have analyzed leukemic cells obtained from bone marrow or peripheral blood. We tested for mutations in the NPM1 gene using peripheral blood plasma and compared results with clinical outcome from a single institution. Analyzing plasma from 98 newly diagnosed patient with AML showed NPM1 mutation in 24 (23%) of patient while only one (4%) of 28 previously untreated patients with myelodysplastic syndrome (MDS) showed NPM1 mutation. Compared with peripheral blood cells, 2 (8%) of the 24 positive patients were negative by cells; none were positive by cells and negative by plasma. Most of the mutations detected (45%) were in patients with FAB classification M2, M4 and M5. In addition to the reported 4 bp insertion, we also detected 4 bp deletion in one patient in cells and plasma. Patients with NPM1 mutation had a significantly higher white blood cell count (P = 0.0009) and a higher blast count in peripheral blood (P = 0.002) and in bone marrow (P = 0.002). Blasts in patients with NPM1 mutant expressed lower levels of HLA-DR (P = 0.005), CD13 (P = 0.02) and CD34 (P < 0.0001), but higher CD33 levels (P = 0.0004). Patients with NPM1 mutation appear to have better chance of responding to standard therapy (P = 0.06). Event free survival of patients with NPM1 mutation was longer (P = 0.056) than in patients with intermediate cytogenetic abnormalities. The most striking difference in survival was in patients who required >35 days to respond to therapy (Figure). Survival was significantly longer in patients with NPM1 mutation requiring >35 days to respond (P = 0.027). This data not only support that NPM1 plays a significant role in the biology and clinical behavior of AML, but also show that plasma DNA is enriched with leukemia-specific DNA and is a reliable source for testing. Figure Figure

Collaboration of the Meningioma 1 (MN1) Oncogene with MLL-Fusions in Pediatric Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3786-3786
Author(s):  
Ting Liu ◽  
Dragana Jankovic ◽  
Laurent Brault ◽  
Sabine Ehret ◽  
Vincenzo Rossi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cell ◽  
Leukemic Cells ◽  
Human Leukemia ◽  
Fusion Genes ◽  
Pediatric Leukemia ◽  
Acute Myeloid

Abstract Expression of meningioma 1 (MN1) has been proposed to be a negative prognostic marker in adult acute myeloid leukemia (AML). In pediatric leukemia, we found overexpression of MN1 in 53 of 88 cases: whereas no MN1 expression was detected in T-cell acute lymphoblastic leukemia (T-ALL), significant amounts of MN1 were found in immature B-cell ALL and most cases of infant leukemia. Interestingly, 17 of 19 cases harboring fusion genes involving the mixed-lineage leukemia (MLL-X) gene showed elevated MN1 expression. Lentiviral siRNA mediated MN1 knock-down resulted in cell cycle arrest and impaired clonogenic growth of 3 MLL-X-positive human leukemia cell lines overexpressing MN1 (THP-1, RS4;11, MOLM-13). In a mouse model of MLL-ENL-induced leukemia we found MN1 to be overexpressed as a consequence of provirus integration. Strikingly co-expression of MN1 with MLL-ENL resulted in significantly reduced latency for induction of an AML phenotype in mice suggesting functional cooperation. Immunophenotyping and secondary transplant experiments suggested that MN1 overexpression seems to expand the L-GMP cell population targeted by the MLL-ENL fusion. Gene expression profiling allowed defining a number of potential MN1 hematopoietic targets. Upregulation of CD34, FLT3, HLF, or DLK1 was validated in bone marrow transiently overexpressing MN1, in MN1-induced mouse acute myeloid leukemia, as well as in pediatric leukemias with elevated MN1 levels. Our work shows that MN1 is overexpressed in a significant fraction of pediatric acute leukemia, is essential for growth of leukemic cells, and that MN1 can act as a cooperating oncogene with MLL-ENL most probably through modification of a distinct gene expression program that leads to expansion of a leukemic progenitor population targeted by MLL-fusion genes.

Constitutive Activation of SHP2 Protein Tyrosine Phosphatase Cooperates with HoxA10 Overexpression for Progression to Acute Myeloid Leukemia in a Murine Model

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 752-752
Author(s):  
Hao Wang ◽  
Stephan Lindsey ◽  
Iwona Konieczna ◽  
Elizabeth Horvath ◽  
Ling Bei ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Protein Tyrosine Phosphatase ◽  
Myeloid Leukemia ◽  
Tyrosine Phosphatase ◽  
Post Translational Modification ◽  
Protein Tyrosine ◽  
Acute Myeloid ◽  
Myeloid Progenitors

Abstract HOX genes encode highly conserved homeodomain (HD) transcription factors and are arranged in four groups (A–D). During definitive hematopoiesis, HOX gene expression is activated 3′ to 5′ through each group. Therefore, HOX1-4 are actively transcribed in hematopoietic stem cells and HOX7-11 in committed progenitors. Under normal conditions, HoxA7-11 expression decreases during CD34+ to CD34− maturation. Abnormal Hox expression is characteristic of several poor prognosis subtypes of Acute Myeloid Leukemia (AML) including AML with translocations or duplications of the MLL gene. In such leukemias, expression of HoxB3, B4 and A7-11 is sustained in CD34−CD38+ cells. In murine bone marrow transplantation experiments, expression of MLL fusion proteins, HoxA9 or HoxA10 induces a myeloproliferative disorder (MPD) characterized by increased neutrophils (PMN). Over time, the mice progress to AML with circulating myeloid blasts. These results suggest overexpression of HoxA9 or HoxA10 is adequate for MPD, but differentiation block (AML) requires additional lesions. We found that HoxA9 and HoxA10 proteins not only decrease in expression during the CD34+ to CD34− transition, but also are tyrosine phosphorylated. In additional studies, we found that HoxA10 tyrosine phosphorylation state is relevant for differentiation stage-specific target gene expression during myelopoiesis. HoxA10 represses genes encoding phagocyte effector proteins in undifferentiated myeloid cells. During myelopoiesis, phosphorylation of conserved HD-HoxA10 tyrosines decreases binding to these genes, permitting phenotypic and functional differentiation. HoxA10 activates transcription of the gene encoding Mkp2 (Dusp4) in myeloid progenitors. Decrease in HoxA10-binding to this gene as differentiation proceeds decreases transcription and renders the cells susceptible to Jnk induced apoptosis. Therefore, we hypothesized that genetic lesions which influence post translational modification might cooperate with HoxA10 overexpression to lead from MPD to AML. In myeloid progenitors, HoxA10 is maintained in a non-phosphorylated state by SHP2 protein tyrosine phosphatase. SHP2 activity decreases as differentiation proceeds. Activating mutations in SHP2 have been described in AML. We found that such activated SHP2 mutants dephosphorylate HoxA10 through out ex vivo myelopoiesis. Therefore, we investigated cooperation between these two leukemia associated abnormalities in vivo. Mice were transplanted with bone marrow overexpressing HoxA10 (or empty vector control) with or without activated SHP2 (E76K). To control for SHP2 overexpression, other mice were transplanted with bone marrow overexpressing HoxA10 and wild type SHP2. Mice transplanted with bone marrow overexpressing HoxA10 (±SHP2) developed MPD which evolved to AML over 4 mos, consistent with previous observations. However, mice transplanted with bone marrow overexpressing HoxA10 and E76K SHP2 developed AML within 4 wks. This rapid development of AML correlated with abnormalities in expression of myeloid specific HoxA10 target genes. These studies indicate the importance of HoxA10 post translational modification for physiologically relevant function and identify cooperating lesions which may be significant for disease progression in human AML.

Clinical Activity, Pharmacokinetics, and Pharmacodynamics of Sorafenib In Pediatric Acute Myeloid Leukemia.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1073-1073
Author(s):  
Hiroto Inaba ◽  
Jeffrey E Rubnitz ◽  
Elaine Coustan-Smith ◽  
Lie Li ◽  
Brian D Furmanski ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Leukemic Cells ◽  
Clinical Activity ◽  
Newly Diagnosed ◽  
Pediatric Acute Myeloid Leukemia ◽  
Rtk Signaling ◽  
Acute Myeloid

Abstract Abstract 1073 Background: Aberrant receptor tyrosine kinase (RTK) signaling arising from genetic abnormalities, such as FLT3-internal tandem duplications (FLT3-ITD), is an important mechanism in the development and growth of acute myeloid leukemia (AML) and is often associated with a poor outcome. Hence, inhibition of RTK signaling is an attractive novel treatment option, particularly for disease that is resistant to conventional chemotherapy. We evaluated the clinical activity of the multikinase inhibitor sorafenib in children with de novo FLT3-ITD–positive AML or relapsed/refractory AML. Methods: Fourteen patients were treated. Six patients with newly diagnosed FLT3- ITD–positive AML (aged 9–16 years; median, 12 years) received 2 cycles of remission induction therapy and then started sorafenib (200 mg/m2 twice daily for 20 days) the day after completing induction II (low-dose cytarabine, daunorubicin, and etoposide). Nine patients (aged 6–17 years; median, 9 years) with relapsed AML (including one treated on the above regimen) received sorafenib alone (2 dose levels; 200 and 150 mg/m2) twice daily for the first week of therapy, concurrently with clofarabine and cytarabine on days 8–12, and then alone from days 13 to 28. Sorafenib pharmacokinetics were analyzed at steady-state on day 8 of sorafenib in patients with newly diagnosed AML and on day 7 in patients with relapsed AML. In patients with relapsed AML, the effect of sorafenib on signaling pathways in AML cells was assessed by flow cytometry. Results: All 6 newly diagnosed patients, including 2 whose AML was refractory to induction I, achieved a complete remission (CR) after induction II; 5 had negative minimal residual disease (MRD; <0.1% AML cells in bone marrow) after induction II. Both patients in this group who relapsed achieved second remissions, one with sorafenib alone and one on the relapse regimen described above. Of the 9 patients with relapsed AML, 6 (4 with FLT3-ITD) were treated with sorafenib 200 mg/m2. All 6 had a >50% decrease in blast percentage and/or bone marrow cellularity after 1 week of sorafenib. After concurrent sorafenib and chemotherapy, 5 of the 9 patients with relapsed AML achieved CR (2 had negative MRD) and 2 achieved a partial remission (PR; 5%-25% AML cells in bone marrow); all 4 patients with FLT3-ITD had a CR or PR. After sorafenib treatment, 6 patients underwent HSCT while 2 with FLT3-ITD who could not receive HSCT were treated with single-agent sorafenib and have maintained CR for up to 8 months. Hand-foot skin reaction (HFSR) or rash occurred in all patients and improved with cessation of sorafenib. Dose-limiting toxicity (DLT, grade 3 HFSR and/or rash) was observed in 3 of the 6 patients with relapsed AML treated with 200 mg/m2 of sorafenib; no DLT was observed at 150 mg/m2. The effect of sorafenib on downstream RTK signaling was tested in the leukemic cells of 4 patients: in most samples, phosphorylation of S6 ribosomal protein and 4E-BP1 was inhibited. The mean (± SD) steady-state concentration (Css) of sorafenib was 3.3 ± 1.2 mg/L in the newly diagnosed group and 6.5 ± 3.6 mg/L (200 mg/m2) and 7.3 ± 3.6 mg/L (150 mg/m2) in those with relapsed AML. In both groups, the mean conversion of sorafenib to sorafenib N-oxide was 27%-35% (approximately 3 times greater than previously reported), and mean sorafenib N-oxide Css was 1.0–3.2 mg/L (2.1-6.7 μM). In a 442-kinase screen, the inhibitory profiles of sorafenib N-oxide and sorafenib were similar, and FLT3-ITD phosphorylation was potently inhibited by both forms (sorafenib N-oxide Kd = 0.070 μM; sorafenib Kd = 0.094 μM). Sorafenib N-oxide inhibited the growth of an AML cell line with FLT3-ITD (IC50 = 0.026 μM) and 4 AML cell lines with wild-type FLT3 (IC50 = 3.9–13.3 μM) at approximately half the potency of sorafenib. Conclusion: In children with de novo FLT3-ITD and relapsed/refractory AML, sorafenib given alone or with chemotherapy induced dramatic responses and inhibited aberrant RTK signaling in leukemic cells. Sorafenib and its active metabolite (sorafenib N-oxide) likely contribute to both efficacy and toxicity. These results warrant the incorporation of sorafenib into future pediatric AML trials. Disclosures: Inaba: Bayer/Onyx: Research Funding. Off Label Use: Sorafenib and clofarabine: both used for treatment of pediatric acute myeloid leukemia.

Inhibition Of LSD1 As a Therapeutic Strategy For The Treatment Of Acute Myeloid Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3964-3964 ◽  
Author(s):  
Ryan G. Kruger ◽  
Helai Mohammad ◽  
Kimberly Smitheman ◽  
Monica Cusan ◽  
Yan Liu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Cell Surface ◽  
Growth Inhibition ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Stem Cell Differentiation ◽  
Ethical Review Process ◽  
Acute Myeloid

Abstract Lysine specific demethylase 1 (LSD1) is a histone H3K4me1/2 demethylase found in various transcriptional co-repressor complexes. These complexes include Histone Deacetylases (HDAC1/2) and Co-Repressor for Element-1-Silencing Transcription factor (CoREST). LSD1 mediated H3K4 demethylation can result in a repressive chromatin environment that silences gene expression. LSD1 has been shown to play a role in development in various contexts. LSD1 can interact with pluripotency factors in human embryonic stem cells and is important for decommissioning enhancers in stem cell differentiation. Beyond embryonic settings, LSD1 is also critical for hematopoietic differentiation. LSD1 is overexpressed in multiple cancer types and recent studies suggest inhibition of LSD1 reactivates the all-trans retinoic acid receptor pathway in acute myeloid leukemia (AML). These studies implicate LSD1 as a key regulator of the epigenome that modulates gene expression through post-translational modification of histones and through its presence in transcriptional complexes. The current study describes the anti-tumor effects of a novel LSD1 inhibitor (GSK2879552) in AML. GSK2879552 is a potent, selective, mechanism-based, irreversible inhibitor of LSD1. Screening of over 150 cancer cell lines revealed that AML cells have a unique requirement for LSD1. While LSD1 inhibition did not affect the global levels of H3K4me1 or H3K4me2, local changes in these histone marks were observed near transcriptional start sites of putative LSD1 target genes. This increase in the transcriptionally activating histone modification correlated with a dose dependent increase in gene expression. Treatment with GSK2879552 promoted the expression of cell surface markers, including CD11b and CD86, associated with a differentiated immunophenotype in 12 of 13 AML cell lines. For example, in SKM-1 cells, increases in cell surface expression of CD86 and CD11b occurred after as early as one day of treatment with EC50 values of 13 and 7 nM respectively. In a separate study using an MV-4-11 engraftment model, increases in CD86 and CD11b were observed as early as 8 hours post dosing. GSK2879552 treatment resulted in a potent anti-proliferative growth effect in 19 of 25 AML cell lines (average EC50 = 38 nM), representing a range of AML subtypes. Potent growth inhibition was also observed on AML blast colony forming ability in 4 out of 5 bone marrow samples derived from primary AML patient samples (average EC50 = 205 nM). The effects of LSD1 inhibition were further characterized in an in vivo mouse model of AML induced by transduction of mouse hematopoietic progenitor cells with a retrovirus encoding MLL-AF9 and GFP. Primary AML cells were transplanted into a cohort of secondary recipient mice and upon engraftment, the mice were treated for 17 days. After 17 days of treatment, control treated mice had 80% GFP+ cells in the bone marrow whereas treated mice possessed 2.8% GFP positive cells (p<0.012). The percentage of GFP+ cells continued to decrease to 1.8% by 1-week post therapy. Remarkably, in a preliminary assessment for survival, control-treated mice succumbed to AML by 28 days post transplant, while treated mice showed prolonged survival. Together, these data demonstrate that pharmacological inhibition of LSD1 may provide a promising treatment for AML by promoting differentiation and subsequent growth inhibition of AML blasts. GSK2879552 is currently in late preclinical development and clinical trials are anticipated to start in 2014. All studies were conducted in accordance with the GSK Policy on the Care, Welfare and Treatment of Laboratory Animals and were reviewed the Institutional Animal Care and Use Committee either at GSK or by the ethical review process at the institution where the work was performed. Disclosures: Kruger: GlaxoSmithKline Pharmaceuticals: Employment. Mohammad:GlaxoSmithKline Pharmaceuticals: Employment. Smitheman:GlaxoSmithKline Pharmaceuticals: Employment. Liu:GlaxoSmithKline Pharmaceuticals: Employment. Pappalardi:GlaxoSmithKline Pharmaceuticals: Employment. Federowicz:GlaxoSmithKline Pharmaceuticals: Employment. Van Aller:GlaxoSmithKline Pharmaceuticals: Employment. Kasparec:GlaxoSmithKline Pharmaceuticals: Employment. Tian:GlaxoSmithKline Pharmaceuticals: Employment. Suarez:GlaxoSmithKline Pharmaceuticals: Employment. Rouse:GlaxoSmithKline Pharmaceuticals: Employment. Schneck:GlaxoSmithKline Pharmaceuticals: Employment. Carson:GlaxoSmithKline Pharmaceuticals: Employment. McDevitt:GlaxoSmithKline Pharmaceuticals: Employment. Ho:GlaxoSmithKline Pharmaceuticals: Employment. McHugh:GlaxoSmithKline Pharmaceuticals: Employment. Miller:GlaxoSmithKline Pharmaceuticals: Employment. Johnson:GlaxoSmithKline Pharmaceuticals: Employment. Armstrong:Epizyme Inc.: Has consulted for Epizyme Inc. Other. Tummino:GlaxoSmithKline Pharmaceuticals: Employment.

The Role of TWIST1 Gene Expression and Hypoxic Microenvironment in Acute Myeloid Leukemia

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3839-3839
Author(s):  
Emilia Carolina Malafaia ◽  
A. Mario Marcondes ◽  
Ekapun Karoopongse ◽  
Daniele Serehi ◽  
Maria de Lourdes L. F. Chauffaille ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Leukemia Cells ◽  
Twist1 Expression ◽  
Disease Biology ◽  
Acute Myeloid

Abstract TWIST1, a basic helix-loop-helix (bHLH) transcription factor, plays a critical role in mesodermal development and organogenesis. Overexpressed TWIST1 has been thoroughly related to epithelial-mesenchymal transition (EMT) in solid tumors (QIN Q et al., 2012) and has been described as an emerging risk factor in hematological neoplasms (MERINDOL et al., 2014). . Many questions remain to be addressed concerning to the role of TWIST1 in acute myeloid leukemia (AML). The understanding of TWIST1 in leukemia cells and its interaction with microenvironment can offer new insights in regards to disease biology and therapeutic targets for patients with AML. Objectives: 1) to evaluate the role of stroma contact and hypoxia in TWIST1 expression in myeloid cell lines. 2) To evaluate the functional impact of overexpressing TWIST1 on KG1a and PL21 cells. 3) To evaluate TWIST1 expression in primary cells of AML patients. Methods: In order to mimic bone marrow microenvironment, myeloid cells were co-cultured with mesenchymal HS5 cell line and PO2 1% was established with Smart -Trak¨ 2 (Sierra Instruments, Inc.) equipment. Quantitative mRNA was determined using TaqMan¨ Universal Master Mix (Applied Biosystems, Foster City, CA) and 3-step standard cycling conditions with sequence-specific primer TWIST1 normalized to the expression of β-actin. KG1a and PL21 cells were transduced with lentivirus vector carrying e-GFP ("enhanced green fluorescence protein") for stable expression of TWIST1. Transduced cells were sorted by FITC fluorochrome and then verified through western blot analysis with TWIST1 antibody. For quantification of apoptosis, cells were labeled with PE-conjugated antibody using annexin V-phycoerythrin and propidium iodide (BD Biosciences, USA). DAPI (4',6- diamidino-2-phenylindole dihydrochloride) was used to stain DNA and determine cell cycle information . Apoptosis and cell cycle were analyzed by FACS -Becton Dickinson Canto II (BD Biosciences). Statistical analysis was assessed with unpaired t test. Results: Hypoxia induced TWIST1 mRNA expression in OCIAML3, PL21, KG1a and ML1 cell lines (fold-increased 46.3, 29.8, 12.9 and 2.3 respectively). Cells expressing endogenous TWIST1 protein (OCIAML3 and ML1) showed resistance to apoptosis in a hypoxic microenvironment (normoxia versus hypoxia: OCI/AML3, 22.6 % vs 11.7% and ML1, 29.8% vs. 7.5%) in contrast, cells not expressing endogenous TWIST1 protein (KG1a and PL21) went to apoptosis in the same conditions. Thus, overexpressing TWIST1 in KG1a and PL21 induced apoptosis protection in hypoxia (KG1a unmodified vs. modified: 17.6 ± 6.3 vs. 2.8 ± 6.3, p=0.04; PL21 unmodified vs. modified: 26.9 ± 10.9 vs. 3.2 ± 0.6, p=0.04) (fig 1). We found increased TWIST1 mRNA levels in bone marrow samples of 23 AML patients (3.88 ± 1.59) compared with 5 healthy controls (0.54 ±0.25) (p= 0.02) (fig 2). Patients in the highest tertile of TWIST1 expression did not show differences in percentage of blasts in bone marrow and complete remission after treatment compared with patients in low and middle tertile. Conclusion: Our data suggest TWIST1 gene expression protects acute myeloid leukemia cells from apoptosis in a hypoxic microenvironment. Moreover, our results showed increased expression of TWIST1 in AML patients. Thus, TWIST1 is a potential gene involved in leukemogenesis and should be further explored to understand disease biology and potential therapeutic targets. Disclosures No relevant conflicts of interest to declare.

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