Deregulated Apoptotic Pathways Point to Effectiveness of IAP Inhibitor Therapy in Acute Myeloid Leukemia.

Abstract Abstract 1275 Poster Board I-297 Core binding factor (CBF) leukemias, characterized by translocations t(8;21) or inv(16)/t(16;16) targeting the core binding factor, constitute acute myeloid leukemia (AML) subgroups with favorable prognosis. However, 40-50% of patients relapse, and the current classification system does not fully reflect the heterogeneity existing within the cytogenetic subgroups. Therefore, illuminating the biological mechanisms underlying these differences is important for an optimization of therapy. Previously, gene expression profiling (GEP) revealed two distinct CBF leukemia subgroups displaying significant outcome differences (Bullinger et al., Blood 2007). In order to further characterize these GEP defined CBF subgroups, we again used gene expression profiles to identify cell line models similar to the respective CBF cohorts. Treatment of these cell lines with cytarabine (araC) revealed a differential response to the drug as expected based on the expression patterns reflecting the CBF subgroups. In accordance, the cell lines resembling the inferior outcome CBF cohort (ME-1, MONO-MAC-1, OCI-AML2) were less sensitive to araC than those modeling the good prognostic subgroup (Kasumi-1, HEL, MV4-11). A previous gene set enrichment analysis had identified the pathways Caspase cascade in apoptosis and Role of mitochondria in apoptotic signaling among the most significant differentially regulated BioCarta pathways distinguishing the two CBF leukemia subgroups. Thus, we concluded that those pathways might be interesting targets for specific intervention, as deregulated apoptosis underlying the distinct subgroups should also result in a subgroup specific sensitivity to apoptotic stimuli. Therefore, we treated our model cell lines with the Smac mimetic BV6, which antagonizes inhibitor of apoptosis (IAP) proteins that are differentially expressed among our CBF cohorts. In general, sensitivity to BV6 treatment was higher in the cell lines corresponding to the subgroup with good outcome. Time-course experiments with the CBF leukemia cell line Kasumi-1 suggested a role for caspases in this response. Interestingly, combination treatment of araC and BV6 in Kasumi-1 showed a synergistic effect of these drugs, with the underlying mechanisms being currently further investigated. Based on the promising sensitivity to BV6 treatment in some cell lines, we next treated mononuclear cells (mostly leukemic blasts) derived from newly diagnosed AML patients with BV6 in vitro to evaluate BV6 potency in primary leukemia samples. Interestingly, in vitro BV6 treatment also discriminated AML cases into two distinct populations. Most patient samples were sensitive to BV6 monotherapy, but about one-third of cases were resistant even at higher BV6 dosage. GEP of BV6 sensitive patients (at 24h following either BV6 or DMSO treatment) provided insights into BV6-induced pathway alterations in the primary AML patient samples, which included apoptosis-related pathways. In contrast to the BV6 sensitive patients, GEP analyses of BV6 resistant cases revealed no differential regulation of apoptosis-related pathways in this cohort. These results provide evidence that targeting deregulated apoptosis pathways by Smac mimetics might represent a promising new therapeutic approach in AML and that GEP might be used to predict response to therapy, thereby enabling novel individual risk-adapted therapeutic approaches. Disclosures Vucic: Genentech, Inc.: Employment. Deshayes:Genentech, Inc.: Employment.

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Epigenetic Silencing of the RUNX3 Gene by Promoter Hypermethylation in Patients with Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v112.11.3341.3341 ◽

2008 ◽

Vol 112 (11) ◽

pp. 3341-3341 ◽

Cited By ~ 1

Author(s):

Sirisha C Maddipoti ◽

Carlos Bueso-Ramos ◽

Hui Yang ◽

Michael Fernandez ◽

Shaoquing Kuang ◽

...

Keyword(s):

Gene Expression ◽

Acute Myeloid Leukemia ◽

Cell Lines ◽

Myeloid Leukemia ◽

Leukemia Cell ◽

Core Binding Factor ◽

Leukemia Cell Lines ◽

Binding Factor ◽

Runx3 Gene ◽

Acute Myeloid

Abstract The RUNX family of transcription factors forms the DNA binding α-chain partner of the heterodimeric core binding factor (CBF) complex. Each of the RUNX proteins, RUNX1 (AML1), RUNX2, and RUNX3 (AML2), can form heterodimers with CBFβ. While the role of RUNX1 in hematopoiesis has previously been well established, recent data have indicated that the RUNX3 gene may also play a key role in the development of human acute leukemias. RUNX3 promoter hypermethylation and downregulation of gene expression have been shown in human gastric and lung cancers, indicative of its function as a tumor suppressor gene. Prior cDNA gene expression arrays of acute myeloid leukemia have noted a downregulation of RUNX3 gene expression in blast cells of inversion 16 AML M4 Eo, with no evidence for somatic mutations in this gene. We therefore wanted to analyze the promoter methylation status of RUNX3 in patients with inversion 16 AML. Using bisulfite treatment of DNA, PCR amplification of the RUNX3 promoter, and pyrosequencing analysis, we initially studied 23 leukemia cell lines. We found that the RUNX3 promoter was hypermethylated at 17 of 23 cell lines, using a cutoff of >15% for hypermethylation, with a mean methylation percentage of 43 and a range of 4–97 (median 31%). We subsequently analyzed RUNX3 gene expression levels in eight of the leukemia cell lines by real-time PCR and were able to demonstrate low baseline expression, with reexpression after treatment with the hypomethylating agent decitabine. We also showed a decrease in percentage methylation of the RUNX3 promoter after treating three of the cell lines with decitabine. We then determined the methylation profile of 81 patients with acute myeloid leukemia (median age 65 [20–84], median WBC at presentation 10 [0.7–114], median percent of marrow blasts 52 [8–94], cytogenetics: inv16 22 (25%), t(8;21) 4 (4%), diploid 23 (27%), the rest abnormal). We observed that 21 of 22 AML M4 Eo samples (95%) were hypermethylated at RUNX3, with a mean methylation percentage of 50 and a range of 4.5–98 (median 49%). Of the other AML subtypes, 20 of 59 patient samples (33%) were hypermethylated, with a mean methylation of 23%, and range of 1–79 (median 12.5%). The RUNX3 promoter was unmethylated in four CD34+ normal controls, and six peripheral blood controls. No correlation between RUNX3 methylation and prognosis was detected in the non inv16 AML cases. Immunohistochemistry performed on the AML M4 Eo bone marrow specimens confirmed the presence of the core-binding factor chimeric protein. We also studied six ALL patient samples and all six were hypermethylated at the RUNX3 promoter, with a mean methylation of 30%, and a range of 21–39 (median 31%). Finally, 19 MDS samples were studied: only four were hypermethylated with an average of 10.5%, and a range of 2.5–47 (median 6.1%). We also analyzed the methylation profile of the RUNX1 and RUNX2 genes on the leukemia cell lines, AML, ALL, and MDS patient samples, and normal controls. The RUNX1 and RUNX2 promoters were universally unmethylated. Our results indicate that epigenetic dysregulation of RUNX3 is likely an important target in the molecular pathway of leukemogenesis in core binding factor leukemia.

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Gene Expression Profiling Identifies Distinct Subclasses in Core Binding Factor Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v106.11.673.673 ◽

2005 ◽

Vol 106 (11) ◽

pp. 673-673

Author(s):

Lars Bullinger ◽

Stephan Kurz ◽

Konstanze Dohner ◽

Claudia Scholl ◽

Stefan Frohling ◽

...

Keyword(s):

Gene Expression ◽

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Expression Patterns ◽

The Other ◽

Rank Test ◽

Core Binding Factor ◽

Log Rank Test ◽

Binding Factor ◽

Acute Myeloid

Abstract Recurrent cytogenetic aberrations have been shown to constitute markers of diagnostic and prognostic value in acute myeloid leukemia (AML). However, even within well-defined cytogenetic AML subgroups with an inv(16) or a t(8;21) we see substantial biological and clinical heterogeneity which is not fully reflected by the current classification system. Therefore, we profiled gene expression in a large series of adult AML patients with core binding factor (CBF) leukemia [inv(16) n=55, t(8;21) n=38] using a whole genome DNA microarray platform in order to better characterize this disease on the molecular level. By unsupervised hierarchical clustering based on 8556 filtered genes we observed that our CBF leukemia samples separated primarily into three different subgroups. While two of the subgroups were characterized by inv(16) and t(8;21) cases, respectively, the third subgroup contained a mixture of both cytogenetic groups. There was no obvious correlation with known secondary aberrations or molecular marker like FLT3-ITD, NRAS and KIT mutations between the cases in the mixed subgroup and the others. However, the newly defined inv(16)/t(8;21)-subgroup (n=35) was characterized by distinct clinical behavior with shorter overall survival times (P=0.029; log rank test) compared to the other two groups. Unsupervised analyses within the inv(16) and t(8;21) cases also revealed corresponding inv(16) and t(8;21) subgroups with a strong trend towards inferior outcome (P=0.11 and P=0.09, respectively; log rank test). Since the primary translocation/inversion events themselves are not sufficient for leukemogenesis, distinct patterns of gene expression found within each of these cytogenetic groups may suggest alternative cooperating mutations and deregulated pathways leading to transformation. Therefore, we performed a supervised analysis to determine the characteristic gene expression patterns underlying the cluster-defined subgroups. We identified 528 genes significantly differentially expressed between the newly defined inv(16)/t(8;21)-subgroup and the other CBF cases (significance analysis of microarrays, false discovery rate < 0.001). Potential candidates for cooperating pathways characterizing the mixed inv(16)/t(8;21)-subgroup included e.g. AVO3, a member of the mTOR pathway, oncogene homologs like LYN and BRAF, as well as FOXO1A and IL6ST which have been previously identified to correlate with outcome in AML (Bullinger et al., N Engl J Med350:1605, 2004). In conclusion, while the observed signatures remain to be validated for their functional relevance, both supervised and unsupervised methods provide numerous insights into the pathogenesis of CBF AML, identifying clinically significant patterns of gene expression, as well as candidate target genes involved in leukemogenesis.

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In Vitro Efficacy of a Novel Liposomal Formulation of a Protein Kinase C Inhibitor In the Treatment of Acute Myeloid Leukemia

Blood ◽

10.1182/blood.v116.21.3282.3282 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3282-3282

Author(s):

Kuan Boone Tan ◽

Leong Uung Ling ◽

Gigi Ngar Chee Chiu

Keyword(s):

Acute Myeloid Leukemia ◽

Cell Line ◽

Cell Lines ◽

Myeloid Leukemia ◽

Conflicts Of Interest ◽

Drug Product ◽

Myelogenous Leukemia ◽

Liposome Encapsulation ◽

Acute Myeloid

Abstract Abstract 3282 The prognosis of patients with acute myeloid leukemia (AML) remains poor, despite the use of the first-line, anthracycline- and cytarabine-based induction chemotherapy aiming to induce complete remission in patients. Given the recent findings that intensive chemotherapy may not benefit older leukemia patients who are not candidates for stem cell transplantation (Kantarjian, H. et al, Blood, 2010; DOI: 10.1182/blood-2010-03-276485) and that the monoclonal antibody-based cytotoxic agent, gemtuzumab ozogamicin, has been voluntarily withdrawn from the market, there is a pressing need to find effective treatment for recurrent AML patients who are >60 years. Safingol [(2S, 3S)-2-amino-1,3-octadecanediol] is a potential anti-cancer bioactive lipid that induces apoptosis through PKC inhibition in leukemia cells and other cancer types. Owing to its poor solubility, safingol is administered as an oil-based emulsion; however, this formulation suffers from severe hemolysis as the dose-limiting toxicity in pre-clinical models, and its toxicity profile is yet to be determined from an ongoing Phase I clinical trial for advanced solid tumors. Liposome is a commonly used drug delivery system to solubilize hydrophobic drugs. It is anticipated that liposome encapsulation of safingol would yield a viable injectable drug product without the need of toxic vehicle such as ethanol or Cremophor-EL, and would substantially reduce the hemolytic toxicity of safingol. In this study, our intention is to develop a suitable liposome formulation of safingol and to test its therapeutic efficacy using human AML cell lines and primary patient samples. Safingol could be formulated into stable liposomes using distearyolphosphatidylcholine and cholesterol with encapsulation efficiency of ∼100%. Safingol was released from the liposomes with a sustained release profile, mainly by a diffusion-controlled mechanism. The extent of hemolysis of 0.5 mM safingol could be significantly reduced from 76% to 14% through liposome encapsulation, as determined by an in vitro hemolysis assay. The cytotoxicity of liposomal safingol was tested with MTT assay on various AML cell lines representing different subtypes, including KG-1 (M1), HL-60 (M2), NB4 (M3), U937 (M5), MV4-11 (M5) and HEL (M6), as well as K562, a cell line of blast crisis of chronic myelogenous leukemia (BC-CML). All cell lines tested responded well to the treatment of liposomal safingol, with IC50 values ranging from 1.5–14 μM. Among the various AML subtypes, NB4 was found to be the most sensitive cell line with the lowest IC50 value of 1.5±0.2 μM. Importantly, liposome encapsulation of safingol did not compromise the ability of the drug to induce apoptosis as compared to the free drug, which was mediated possibly through a mechanism dependent on the generation of reactive oxygen species and caspase activation. Liposomal safingol was further tested in 10 leukemic patient samples, and the formulation was able to induce complete loss of viability of the primary cell samples at 20 μM after 72 h of treatment. Taken together, our results demonstrated the therapeutic potential of liposomal safingol for the treatment of various AML subtypes. Further evaluation of the pharmacokinetics and the efficacy of the formulation in animal models is warranted. Disclosures: No relevant conflicts of interest to declare.

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Clinical and experimental efficacy of gemtuzumab ozogamicin in core binding factor acute myeloid leukemia

Hematology Reports ◽

10.4081/hr.2017.7028 ◽

2017 ◽

Vol 9 (3) ◽

Cited By ~ 6

Author(s):

Michele Gottardi ◽

Federico Mosna ◽

Sergio De Angeli ◽

Cristina Papayannidis ◽

Anna Candoni ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Disease Free Survival ◽

Gemtuzumab Ozogamicin ◽

Core Binding Factor ◽

Free Survival ◽

Binding Factor ◽

Clonogenic Potential ◽

Acute Myeloid

Leukemia-initiating cells of core binding factor (CBF) acute myeloid leukemia (AML) likely derive from early committed hematopoietic precursors expressing CD33. As such, targeting CD33 could ameliorate the chance of cure of CBF AML patients. We compared 12 CBF AML patients treated with Fludarabine, Cytarabine, Idarubicin and Gemtuzumab Ozogamicin (FLAI-GO regimen) with 25 CBF AML patients treated with the same schedule, but without GO. With the limit of small numbers, we observed a consistent trend toward better overall survival, disease free survival and event free survival in the FLAI-GO group. We also demonstrated the ability of GO to induce the disappearance <em>in vitro</em> of the AML1-ETO molecular transcript in a polymerase chain reaction-positive graft without decreasing the clonogenic potential of CD34+/CD38- cells. This represent the proof of principle for using GO in a purging strategy before autologous stem cell transplantation. Therefore, our data argue in favor of the reinstitution of GO in the therapy of CBF AML.

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FLT3 Expression Is Increased by MEIS1 and Collaborates with NUP98-HOX Fusion Genes in the Induction of Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v104.11.2552.2552 ◽

2004 ◽

Vol 104 (11) ◽

pp. 2552-2552

Author(s):

Lars Palmqvist ◽

Nicolas Pineault ◽

Bob Argiropoulos ◽

Adrian Wan ◽

Keith R. Humphries

Keyword(s):

Acute Myeloid Leukemia ◽

Cell Line ◽

Cell Lines ◽

Myeloid Leukemia ◽

Parental Cell ◽

Fusion Genes ◽

Flt3 Ligand ◽

Flt3 Expression ◽

Acute Myeloid

Abstract The TALE family member and HOX cofactor MEIS1 is important in leukemic transformation. MEIS1 has, although non-leukemogenic on its own, been shown to strongly collaborate with several HOX genes and NUP98-HOX fusions to induce acute myeloid leukemia (AML). We have recently described a novel in vitro culture system of cell lines established from murine primary bone marrow cells transduced with the AML-associated fusion gene NUP98-HOXD13 or an engineered NUP98-HOXA10 fusion. These pre-leukemic NUP98-HOX cell lines are transplantable and can efficiently be converted into AML-inducing cells upon MEIS1 transduction. Conveniently, the MEIS1 transduced cells can be purified and preserve their leukemogenic potential even after extensive in vitro expansion. Thus, the availability of the NUP98-HOX cell lines system provided the opportunity to investigate and characterize the mechanism of MEIS1-mediated AML-conversion. Potentially interesting target or candidate genes were screened for expression changes between the parental pre-leukemic lines and AML-inducing MEIS1 transduced cell lines with quantitative RT-PCR and Western blotting. Aberrant expression or mutations of the receptor tyrosine kinase FLT3 gene is a common finding in human AML. Interestingly, Flt3 was found induced 5 to 10 fold in MEIS1 transduced cell lines compared to the parental cell lines. The observed increase in Flt3 expression provided the MEIS1 transduced cells with Flt3 ligand driven growth. This was not seen in the parental cell lines, which could not proliferate with Flt3 ligand as single cytokine or with a MEIS1-homeodomain mutant expressing cell line. Importantly, the Flt3 inhibitor AG1295 could block the proliferative effect of the Flt3 ligand in the MEIS1 transduced cell lines. To test whether Flt3 could substitute for MEIS1-mediated induction of AML in NUP98-HOX pre-leukemic cells, a NUP98-HOXA10 cell line was transduced with an MSCV-Flt3-IRES-YFP construct. The resulting Flt3-transduced cells were shown to express Flt3 at levels similar to that of MEIS1 transduced cells without any significant increase in endogenous Meis1 expression. Transplantation of these cells into mice led to lethal and transplantable AML with a median disease onset of 116 days (n=8) compared to 59 days for MEIS1 (n=4), whereas control transplants remained healthy (n=2). In conclusion, this study demonstrates that MEIS1 can induce Flt3 expression and that Flt3 can collaborate with NUP98-HOX fusion genes in the induction of acute myeloid leukemia. Furthermore, theses results suggest a model in which the leukemogenic synergism of MEIS1 on HOX-mediated leukemia might in part be mediated through FLT3-dependent pathways.

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The PARP Inhibitor Olaparib Antagonizes Leukemic Growth Induced By TET1 Overexpression in AML1-ETO Positive Acute Myeloid Leukemia

Blood ◽

10.1182/blood.v128.22.4063.4063 ◽

2016 ◽

Vol 128 (22) ◽

pp. 4063-4063 ◽

Cited By ~ 1

Author(s):

Shiva Bamezai ◽

Jing He ◽

Deniz Sahin ◽

Fabian Mohr ◽

Fabio Ciccarone ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Cell Growth ◽

Cell Line ◽

Cell Lines ◽

Myeloid Leukemia ◽

Parp Inhibitor ◽

Leukemic Cell ◽

Aberrant Expression ◽

Acute Myeloid

Abstract DNA methylation patterns are highly deregulated in human acute myeloid leukemia (AML) cases and stratify AML patient samples into different subgroup. AML1-ETO is the most commonly occurring fusion gene in AML and these AML cases exhibit an aberrant and distinct methylation pattern. So far, the underlying mechanisms for this are only poorly understood. The TET1 dioxygenase has recently emerged as an important epigenetic modifier: by catalyzing the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) TET1 plays an important role in active demethylation, thereby regulating a variety of biological processes. It was linked to tumorigenesis based on the observation that its expression is frequently deregulated in solid cancer. However, the role of TET1 in AML1-ETO+ (AE+)human AML cases is yet unexplored. Using quantitative real time (qRT)- PCR we now show that AE+ AML is characterized by high and aberrant expression of TET1: the gene was significantly higher expressed in the majority of AE+ patients (n=7, p<0.01) compared to other AML subtypes such as inv(16) (n=11), PML-RARα+ (n=31), cytogenetically normal (CN)-AML patients (n=33) and CD34+ normal BM cells (n=4). This observation was consistent with published cDNA microarray data on large patient cohorts (Haferlach et al., JCO 2010, p<0.008 t-test, p<0.01 Anova) and recently published transcriptome data (TCGA) of AML patients. In contrast to TET1, TET2 and TET3 did not show significant higher expression in AE+ patients compared to other AML subtypes. In line with patient data, TET1 was highest expressed in the AE+ AML cell line KASUMI-1 and SKNO-1 compared to other AML cell lines (p<0.05 and n=3). Compared to normal CD34+ and myeloid (CD33+, CD15+ and CD14+) cells (n=3), TET1 was 10-fold and 16-fold higher expressed in AE+ patient samples (n= 7). Aberrant expression of TET1 in AE+ leukemic cells was associated with hypomethylation of its promoter and enrichment for H3K4me3 euchromatic marks at its promoter as determined by LC/MS and ChIP-qPCR respectively. Knockdown (KD) of TET1 mRNA using two short hairpin RNAs (shRNAs) in AE+ AML cell lines impaired their cell growth and clonogenicity by over 50% in vitro (n=3 and p<0.01). shRNA mediated depletion of TET1 did not impact the cell growth and clonogenicity of the TET1 negative cell line RAJI, ruling out off target effects of the shRNAs (n=3). In mice, KD of Tet1 in leukemic bone marrow cells expressing the truncated leukemogenic AML1-ETO9a (AE9a) fusion, dramatically inhibited cell growth (>60% compared to scrambled, n=3, p<0.01), clonogenicity (>50-70% reduction in primary CFCs, p<0.01, n=3) and importantly delayed onset of leukemia in vivo (median survival 35 days for scr vs 80 days for shRNA mice, n=4/arm, p<0.03). Tet1-knock-out c-kit+ hematopoietic stem and progenitor cells (HSPCs) transduced with AE9a showed reduced primary colony formation and impaired serial replanting capacity in vitro compared to AE9a transduced Tet1-wild-type HSPCs (>50% and >70%, respectively; p<0.001, n=3). Global analysis of 5hmC and 5mC levels using hMeDIP/MeDIP-seq performed on TET1 depleted KASUMI-1 cells revealed lower global 5hmC levels and increase in 5mC as compared to cells transduced with scrambled control (n=2). 3324 promoter regions lost 5hmC and gained 5mC upon TET1 depletion (-5kTSS, Fold enrichment cut off <2-fold, q-value<1e5). Recent studies have shown that PARP activity induces TET1 expression by regulating its promoter epigenetically. We could show that aberrant TET1 expression could be antagonized by the PARP inhibitor olaparib in AE+ leukemic cell lines. Furthermore, olaparib treatment decreased 5hmC levels and reduced cell growth and clonogenicity of human AE+ cell lines and of the murine AE9a+ leukemic cell line in vitro (n=3, p<0.01). In conclusion, our data indicates that aberrant TET1 expression contributes to the growth of AE+ AML by maintaining the 5-hydroxymethylome and that the PARP inhibitor olaparib can at least partially antagonize the oncogenic effect of TET in AML. Disclosures Mulaw: NuGEN: Honoraria. Buske:Celltrion, Inc.: Consultancy, Honoraria.

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Phosphotyrosine profiling identifies the KG-1 cell line as a model for the study of FGFR1 fusions in acute myeloid leukemia

Blood ◽

10.1182/blood-2006-06-026666 ◽

2006 ◽

Vol 108 (13) ◽

pp. 4202-4204 ◽

Cited By ~ 51

Author(s):

Ting-Lei Gu ◽

Valerie L. Goss ◽

Cynthia Reeves ◽

Lana Popova ◽

Julie Nardone ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Cell Line ◽

Cell Lines ◽

Myeloid Leukemia ◽

Leukemia Cell ◽

Mass Spectrometry Analysis ◽

Leukemia Cell Lines ◽

Fgfr1 Gene ◽

Acute Myeloid

Abstract The 8p11 myeloproliferative syndrome (EMS) is associated with translocations that disrupt the FGFR1 gene. To date, 8 fusion partners of FGFR1 have been identified. However, no primary leukemia cell lines were identified that contain any of these fusions. Here, we screened more than 40 acute myeloid leukemia cell lines for constitutive phosphorylation of STAT5 and applied an immunoaffinity profiling strategy to identify tyrosine-phosphorylated proteins in the KG-1 cell line. Mass spectrometry analysis of KG-1 cells revealed aberrant tyrosine phosphorylation of FGFR1. Subsequent analysis led to the identification of a fusion of the FGFR1OP2 gene to the FGFR1 gene. Small interfering RNA (siRNA) against FGFR1 specifically inhibited the growth and induced apoptosis of KG-1 cells. Thus, the KG-1 cell line provides an in vitro model for the study of FGFR1 fusions associated with leukemia and for the analysis of small molecule inhibitors against FGFR1 fusions.

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Gene-expression profiling identifies distinct subclasses of core binding factor acute myeloid leukemia

Blood ◽

10.1182/blood-2006-10-049783 ◽

2007 ◽

Vol 110 (4) ◽

pp. 1291-1300 ◽

Cited By ~ 91

Author(s):

Lars Bullinger ◽

Frank G. Rücker ◽

Stephan Kurz ◽

Juan Du ◽

Claudia Scholl ◽

...

Keyword(s):

Gene Expression ◽

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Mapk Signaling ◽

Tyrosine Kinase Domain ◽

Gene Transcript ◽

Core Binding Factor ◽

Cell Counts ◽

Binding Factor ◽

Acute Myeloid

Abstract Core binding factor (CBF) leukemias, characterized by either inv(16)/t(16;16) or t(8;21), constitute acute myeloid leukemia (AML) subgroups with favorable prognosis. However, there exists substantial biologic and clinical heterogeneity within these cytogenetic groups that is not fully reflected by the current classification system. To improve the molecular characterization we profiled gene expression in a large series (n = 93) of AML patients with CBF leukemia [(inv (16), n = 55; t(8;21), n = 38)]. By unsupervised hierarchical clustering we were able to define a subgroup of CBF cases (n = 35) characterized by shorter overall survival times (P = .03). While there was no obvious correlation with fusion gene transcript levels, FLT3 tyrosine kinase domain, KIT, and NRAS mutations, the newly defined inv(16)/t(8;21) subgroup was associated with elevated white blood cell counts and FLT3 internal tandem duplications (P = .011 and P = .026, respectively). Supervised analyses of gene expression suggested alternative cooperating pathways leading to transformation. In the “favorable” CBF leukemias, antiapoptotic mechanisms and deregulated mTOR signaling and, in the newly defined “unfavorable” subgroup, aberrant MAPK signaling and chemotherapy-resistance mechanisms might play a role. While the leukemogenic relevance of these signatures remains to be validated, their existence nevertheless supports a prognostically relevant biologic basis for the heterogeneity observed in CBF leukemia.

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