Study Of Activity Of E6201, a Dual FLT3 and MEK Inhibitor, In Acute Myelogenous Leukemia With FLT3 Or RAS Mutation

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2683-2683 ◽  
Author(s):  
Weiguo Zhang ◽  
Gautam Borthakur ◽  
Chen Gao ◽  
Ye Chen ◽  
Yong S. Lan ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Cell Lines ◽  
Inhibitory Activity ◽  
Point Mutations ◽  
Myelogenous Leukemia ◽  
Vehicle Group ◽  
Wild Type ◽  
Ras Mutation ◽  
Induced Apoptosis ◽  
Resistant Cells

Abstract Internal tandem duplication (ITD) or point mutation of Fms-like tyrosine kinase 3 (FLT3) and N/KRAS mutations in patients with acute myeloid leukemia (AML) lead to aberrant activation of FLT3 and/or RAS–mitogen-activated protein kinase (MAPK) pathways and are associated with poor prognosis (Kottaridis et al, Leuk Lymphoma Vol. 44:905, 2003; Thiede et al, Blood Vol. 99;4326, 2002). Therapy with inhibitors targeting these pathways individually may at best result in short lasting responses in the appropriate mutational context (Borthakur et al, Haematologica Vol. 96:62, 2011; Cortes et al, Blood Vol. 114:636a, 2009). Persistent activation of MEK/ERK signaling pathway is seen in cells resistant to FLT3-ITD inhibitor sorafenib that harbor acquired point mutations of FLT3 in tyrosine kinase domains in addition to ITD mutation (Moore et al, Leukemia Vol. 26:1462, 2012). E6201 is a MEK1/FLT3 dual inhibitor with inhibitory activity in low nanomolar concentrations against both targets. We tested E6201 against AML cells including FLT3-inhibitor resistant cells, AML patient samples and investigated its efficacy in murine AML model. E6201 inhibited cell growth and induced apoptosis in AML cells with FLT3 ITD mutations (including sorafenib-resistant cells harboring ITD plus N676D/Y842C point mutations) at nanomolar levels, and showed 600 to 1000-fold more selective activity against cells with FLT3-ITD mutations than those with FLT3-WT (IC50s 0.003µM, 0.005 and 0.002µM, respectively, in Ba/F3-ITD and FLT3-ITD mutant MOLM13 and MV4-11cells compared to 3.18µM in Ba/F3-FLT3-WT cells). In addition, OCI/AML3 cells [FLT3 and RAS wild-type(WT)], which have high basal p-ERK level and are resistant to most of chemotherapeutic drugs, were sensitive to E6201 (IC50 = 0.037µM). Consistent with its MEK1 inhibitory activity, E6201 was more active against NRAS mutation carrying OCI/AML3 and MV4-11 cells than their NRAS-WT isogenic cells. E6201-induced apoptosis appears to be p53 dependent as p53-wild-type OCI/AML3 and MOLM13 cells were significantly more sensitive compared to their paired p53-knockdown cells. EC50 of E6201 was at sub-micromolar levels in all 5 FLT3-ITD mutant primary AML samples, which included one with FLT3-ITD/RAS dual mutation. NOG mice bearing xenografts of MOLM13-Luc-GFP (FLT3-ITD mutated) cells were treated with E6201 i.v. starting on day 5 after leukemia cell injection until day 21 on a twice-per-week schedule. Bioluminescence imaging revealed that the tumor burden (mean luminescence) was reduced (3.1 x 106 and 2.7 x 106vs. 5.6 x 106 Photons/sec, p< .01 in 20mg/kg and 40mg/kg groups compared with vehicle group)(Fig 1) and histologically leukemia cells infiltrations were profoundly reduced in the bone marrows, spleens, livers and lungs on Day 9 after first drug treatment. Additionally, the median survival was modestly extended from 16 days of vehicle-treated mice to 18 days of E6201-treated mice (P <0.01). Mechanistically, E6201 significantly suppressed p-FLT3 and p-ERK in all tested FLT3 mutant AML cell lines and p53 wild-type OCI/AML3 cells. In addition, decrease of Bcl-xL and Mcl-1 levels and increase of cleaved-caspase-3 was observed in all FLT3 mutant cell lines after treatment with E6201 for 24 hours. In conclusion, E6201 is active against AML cells with FLT3 and/or RAS mutation. A clinical trial is in development in FLT3 and/or RAS mutant AML. Disclosures: Borthakur: Eisai, Inc.: Research Funding. Nomoto:Eisai, Inc.: Employment. Zhao:Eisai, Inc.: Employment.

Targeting BCR-ABL and Its Downstream Signaling Cascade as Therapy for Chronic Myelogenous Leukemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2964-2964 ◽  
Author(s):  
Nicholas J. Donato ◽  
Ji Wu ◽  
Ling Y. Kong ◽  
Feng Meng ◽  
Waldemar Priebe ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Growth ◽  
Tyrosine Kinase ◽  
Point Mutations ◽  
Myelogenous Leukemia ◽  
Therapeutic Activity ◽  
Wild Type ◽  
Growth And Survival ◽  
Downstream Signaling ◽  
Kinase Inhibitory Activity

Abstract BCR-ABL is an unregulated tyrosine kinase expressed as a consequence of chromosomal translocation in chronic myelogenous leukemia (CML). The tyrosine kinase activity of BCR-ABL activates signaling cascades that induce cytokine independence and transformation of myeloid progenitor cells. Targeted inhibition of this kinase with specific inhibitors (imatinib or BMS-354825) is a very effective therapy for some CML patients but resistance to these agents (through point mutations and other mechanisms) leads to advanced disease with very few therapeutic options. An alternate therapeutic strategy is to reduce BCR-ABL expression or its critical downstream signaling elements important for transformation. We examined BCR-ABL signaling elements and gene expression changes that occur in CML cells following kinase inhibition by imatinib in newly established imatinib sensitive and resistant cells to identify critical signaling elements involved in CML cell death. Imatinib rapidly and progressively suppressed c-myc expression in imatinib sensitive but not resistant cells prior to the onset of apoptosis. These results suggested that c-myc expression was regulated by BCR-ABL signaling and may play a role in CML tumorigenicity. To confirm a role for c-myc in CML cell growth and/or survival, c-myc expression was specifically down-regulated by siRNA using a novel electroporation instrument (AMAXA) that permits high level gene transfer with limited toxicity in CML cell lines. Jak2 siRNA was used as a control. c-myc, but not Jak2 siRNA, suppressed c-myc expression and cell growth and survival in both imatinib sensitive and resistant CML cells, suggesting that targeted suppression of c-myc may have therapeutic activity against both kinase inhibitor sensitive and resistant CML cells. Since the tyrphostin AG490 was previously shown to inhibit c-myc expression in CML cells through its inhibitory effects on Jak2, we screened a series of &gt; 200 AG490 derivatives for their ability to rapidly reduce c-myc expression in hematological malignancies. After several rounds of testing we synthesized an agent (WP-1066) capable of rapid c-myc downregulation (beginning 1–5 min after treatment with 1–2 microM) but poor Jak2 kinase inhibitory activity (IC50 &gt; 100 microM). These results suggested a more direct effect of WP-1066 on c-myc protein expression than AG490 and mechanistic studies suggest that WP-1066 reduces c-myc protein stability but does not affect c-myc gene expression. In BCR-ABL expressing cells WP-1066 rapidly reduced c-myc protein levels in CML cells and inhibited the growth and survival of cell lines or patient specimens expressing wild-type or mutant forms of BCR-ABL that effect tyrosine kinase inhibitory activity (T315I in BV-173R cells). Equal concentrations of imatinib or WP-1066 reduced BCR-ABL activation and downstream signaling (Stat5 phosphorylation) in CML cells. However, WP-1066 differed from imatinib in its ability to downregulate BCR-ABL protein expression without affects on c-abl or Stat5 expression. Similar results were obtained in clinical specimens taken from patients with BCR-ABL point mutations that mediate imatinib (or BMS-354825) resistance. Nude mouse studies demonstrated that WP-1066 reduced the growth of K562 tumors to an extent similar to that of imatinib. Together these results suggest that WP-1066 downregulates BCR-ABL and c-myc expression, induces apoptosis in CML cells expressing wild-type or mutant BCR-ABL and may have therapeutic activity in imatinib (or BMS-354825) resistant CML tumors.

Combination of Crenolanib with Sorafenib Produces Synergistic Pro-Apoptotic Effects in FLT3-ITD-Inhibitor-Resistant Acute Myelogenous Leukemias with FLT3 Mutations

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3591-3591 ◽  
Author(s):  
Chen Gao ◽  
Weiguo Zhang ◽  
Rodrigo Jacamo ◽  
Abhijit Ramachandran ◽  
Donald Small ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Cell Lines ◽  
Kinase Inhibitor ◽  
Conflicts Of Interest ◽  
Single Agent ◽  
Point Mutations ◽  
Type I ◽  
Type Ii ◽  
Apoptotic Effects ◽  
Resistant Cells

Abstract Abstract 3591 Activating mutations in the FLT3 gene, including internal tandem duplications (ITDs) and missense point mutations of the tyrosine kinase domain (TKD), are frequently observed in AML patients and confer poor prognosis (1). Targeting FLT3 ITD mutations using the multi-kinase inhibitor Sorafenib (a type II kinase inhibitor, which binds to inactive conformation of a kinase ATP pocket)(2) showed impressive anti-leukemia effects in FLT3-ITD mutated AML in Phase I/II clinical trials (3) However, resistance/relapse develops regularly during prolonged Sorafenib therapy (4), in part through acquired point mutations of TKD domains. We postulated that the conformational change of FLT3 protein resulting from acquired point mutations limits the accessibility of sorafenib and leads to resistance (5, 6). Recently, Crenolanib, a novel PDGFRβ tyrosine kinase inhibitor, showed impressive anti-tumor effects by targeting the active conformation of a kinase ATP pocket of FLT3 protein (a type I kinase inhibitor). Therefore, we hypothesize that targeting different sites of FLT3 protein simultaneously using different types of kinase inhbitors may be effective in overcoming sorafenib resistance. We here report that Crenolanib has anti-leukemic activity in Sorafenib-resistant cells which harbor both ITD and acquired TKD point mutations i, and that its combination with Sorafenib in Sorafenib-resistant cells exerts synergistic pro-apoptotic effects. The anti-leukemic activity of Crenolanib was assessed by measuring cell viability (trypan Blue exclusion) and apoptosis induction (annexin V/propidium iodide staining) in isogenic murine Ba/F3 AML cell lines with stable transfection of human FLT3-ITD mutations, in Sorafenib resistant Ba/F3-ITD-Res cells derived from long-term, low-dose exposure of Ba/F3-ITD to Sorafenib in vitro, which harbor N676D and Y842C mutations, and Sorafenib-resistant cell lines Ba/F3-ITD+676, Ba/F3-ITD+842 and Ba/F3-ITD+676/842 which carry ITD and TKD point mutations (N676D, Y842C and N676D/Y842C mutations, respectively). Effects of combinatorial regimen employing Crenolanib and Sorafenib were analyzed using CalcuSyn software (combination index (CI) : CI<1 = synergistic, CI>1 = antagonistic effects). Results show that single agent Crenolanib induced cell growth arrest in leukemia cells Ba/F3-ITD, Ba/F3-ITD+676, Ba/F3-ITD+842 and Ba/f3-ITD+842/676, at IC50s of 0.012, 0.012 0.037 and 0.038uM, respectively, and induced apoptosis (EC50s) at 0.17, 0.23, 0.19, and 0.22uM, respectively, after 72 hours of treatment. Western Blot showed that Crenolanib profoundly suppressed phosphorylation levels of FLT3 protein and its downstream targets ERK and AKT and induced cleavage of caspase 3. Sorafenib-resistant cells Baf3-ITD+Res and Baf3-ITD+842/676 (EC50s for Sorafenib were 4.2 ± 1.50 and 6.6 ± 0.53 μM, respectively) were exposed to submicromolar concentrations of Crenolanib and Sorafenib concomitantly for 48 h, resulting in impressive synergistic pro-apoptotic effects (CIs were 0.56 ± 0.12 and 0.36 ± 0.04, respectively), implying high synergistic potency of Type I and Type II FLT3 kinase inhibitors, when given concomitantly. In vivo experiments are in progress. Our findings provide therapeutic rationale for a combinatorial treatment strategy with Crenolanib and Sorafenib of FLT-ITD inhibitor-refractory AML. Disclosures: No relevant conflicts of interest to declare.

Suppression of leukemia expressing wild-type or ITD-mutant FLT3 receptor by a fully human anti-FLT3 neutralizing antibody

Blood ◽  
2004 ◽  
Vol 104 (4) ◽  
pp. 1137-1144 ◽  
Author(s):  
Yiwen Li ◽  
Hongli Li ◽  
Mei-Nai Wang ◽  
Dan Lu ◽  
Rajiv Bassi ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Neutralizing Antibody ◽  
Myelogenous Leukemia ◽  
Mitogen Activated Protein Kinase ◽  
Enzyme Linked Immunosorbent Assay ◽  
Human Leukemia ◽  
Wild Type ◽  
Antibody Treatment

AbstractFMS-like tyrosine kinase 3 (FLT3), a class III receptor tyrosine kinase, is expressed at high levels in the blasts of approximately 90% of patients with acute myelogenous leukemia (AML). Internal tandem duplications (ITDs) in the juxtamembrane domain and point mutations in the kinase domain of FLT3 are found in approximately 37% of AML patients and are associated with a poor prognosis. We report here the development and characterization of a fully human anti-FLT3 neutralizing antibody (IMC-EB10) isolated from a human Fab phage display library. IMCEB10 (immunoglobulin G1 [IgG1], κ) binds with high affinity (KD = 158 pM) to soluble FLT3 in enzyme-linked immunosorbent assay (ELISA) and to FLT3 receptor expressed on the surfaces of human leukemia cell lines. IMC-EB10 blocks the binding of FLT3 ligand (FL) to soluble FLT3 in ELISA and competes with FL for binding to cell-surface FLT3 receptor. IMC-EB10 treatment inhibits FL-induced phosphorylation of FLT3 in EOL-1 and EM3 leukemia cells and FL-independent constitutive activation of ITD-mutant FLT3 in BaF3-ITD and MV4;11 cells. Activation of the downstream signaling proteins mitogen-activated protein kinase (MAPK) and AKT is also inhibited in these cell lines by antibody treatment. The antibody inhibits FL-stimulated proliferation of EOL-1 cells and ligand-independent proliferation of BaF3-ITD cells. In both EOL-1 xenograft and BaF3-ITD leukemia models, treatment with IMC-EB10 significantly prolongs the survival of leukemia-bearing mice. No overt toxicity is observed with IMC-EB10 treatment. Taken together, these data demonstrate that IMC-EB10 is a specific and potent inhibitor of wild-type and ITD-mutant FLT3 and that it deserves further study for targeted therapy of human AML. (Blood. 2004;104:1137-1144)

The Anti-FLT3 Monoclonal Antibody EB10 Is Cytotoxic to FLT3 Inhibitor Resistant Cells In Vivo.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1511-1511
Author(s):  
Obdulio Piloto ◽  
Melissa Griesemer ◽  
Bao Nguyen ◽  
Li Li ◽  
Yiwen Li ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Tyrosine Kinase ◽  
Cell Lines ◽  
Continuous Treatment ◽  
Cross Resistance ◽  
Parent Cell ◽  
Wild Type ◽  
Flt3 Inhibitor ◽  
Resistant Cells

Abstract The class III receptor tyrosine kinase, FLT3, has been shown to play a role in leukemogenesis, particularly in acute myeloid leukemias (AML) and acute lymphoblastic leukemias (ALL). This finding has spurred the development of tyrosine kinase inhibitors (TKI) targeting wild-type and mutant FLT3, and these drugs have shown activity in clinical trials. However, as has been observed with Gleevac for treatment of chronic myeloid leukemia, continuous treatment with TKIs may select for resistant clones. Immunotherapy targeting FLT3 may prove efficacious against FLT3-expressing resistant cells since their mode of action is not dependent on FLT3 inhibition. To study resistance to TKIs against FLT3 we developed resistant human cell lines by co-culturing MOLM14 and SEM-K2 cells, expressing FLT3/ITD mutant and wild type FLT3, respectively, with increasing concentrations of the FLT3 inhibitor CEP-701. The resulting cell lines, MOLM14(R) and SEM-K2(R), are resistant to CEP-701 induced cytotoxicity as well as to other selective FLT3 TKIs, CEP-5214 and PKC412. Cross resistance to CEP-701, CEP-5214 and PKC412 was also observed when MOLM14 and SEM-K2 cells were co-cultured with CEP-5214 or PKC412, instead of CEP-701. Western blot analysis reveals that CEP-701, CEP-5214 and/or PKC412 still inhibit FLT3 and downstream STAT5, Akt and MAPK pathways in MOLM14(R) and SEM-K2(R) cells. Sequencing of FLT3 from the resistant clones confirmed that the resistance was not the result of drug resistance mutations in FLT3. This indicates that the observed resistance to CEP-701, CEP-5214 and PKC412 is due to selection of FLT3-independent clones during co-culture with anti-FLT3 TKIs. To see if anti-FLT3 immunotherapy would still be active against resistant cells, MOLM14(R) and SEM-K2(R) cells were injected into NOD/SCID mice and treated with IMC-EB10, an unconjugated monoclonal antibody against FLT3. These in vivo studies demonstrate that IMC-EB10 still reduces leukemic engraftment and prolongs survival of mice injected with the resistant cell lines, to comparable levels observed with the parent cell lines. In conclusion, our data indicates that culturing leukemic cells with increasing concentrations of selective FLT3 TKIs can result in clones that are FLT3 independent and that anti-FLT3 immunotherapy is still cytotoxic to these resistant cells in vivo. An approach combining FLT3 TKIs with anti-FLT3 antibodies may prove superior and result in reduced chance of developing resistance.

scholarly journals Prolonged exposure to FLT3 inhibitors leads to resistance via activation of parallel signaling pathways

Blood ◽  
2006 ◽  
Vol 109 (4) ◽  
pp. 1643-1652 ◽  
Author(s):  
Obdulio Piloto ◽  
Melissa Wright ◽  
Patrick Brown ◽  
Kyu-Tae Kim ◽  
Mark Levis ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Signaling Pathways ◽  
Cell Lines ◽  
Kinase Inhibitors ◽  
Prolonged Exposure ◽  
Cellular Transformation ◽  
Mapk Signaling ◽  
Resistant Cell ◽  
Myelogenous Leukemia ◽  
Continuous Treatment

Abstract Continuous treatment of malignancies with tyrosine kinase inhibitors (TKIs) may select for resistant clones (ie, imatinib mesylate). To study resistance to TKIs targeting FLT3, a receptor tyrosine kinase that is frequently mutated in acute myelogenous leukemia (AML), we developed resistant human cell lines through prolonged coculture with FLT3 TKIs. FLT3 TKI-resistant cell lines and primary samples still exhibit inhibition of FLT3 phosphorylation on FLT3 TKI treatment. However, FLT3 TKI-resistant cell lines and primary samples often show continued activation of downstream PI3K/Akt and/or Ras/MEK/MAPK signaling pathways as well as continued expression of genes involved in FLT3-mediated cellular transformation. Inhibition of these signaling pathways restores partial sensitivity to FLT3 TKIs. Mutational screening of FLT3 TKI-resistant cell lines revealed activating N-Ras mutations in 2 cell lines that were not present in the parental FLT3 TKI-sensitive cell line. Taken together, these data indicate that FLT3 TKI-resistant cells most frequently become FLT3 independent because of activation of parallel signaling pathways that provide compensatory survival/proliferation signals when FLT3 is inhibited. Anti-FLT3 mAb treatment was still cytotoxic to FLT3 TKI-resistant clones. An approach combining FLT3 TKIs with anti-FLT3 antibodies and/or inhibitors of important pathways downstream of FLT3 may reduce the chances of developing resistance.

Abstract 1042: Viral Chemokine Modulating Protein, M-T7, Interrupts Chemokine : Glycosaminoglycan (GAG) Interaction: M-T7 Inhibitory Activity is Dependent upon Y46 and V210 aminoacid residues

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Erbin Dai ◽  
Dana McIvor ◽  
Liying Liu ◽  
Ganesh Munaswamy-Ramanujam ◽  
Yunming Sun ◽  
...  
Keyword(s):  
Cell Migration ◽  
Cell Invasion ◽  
Inhibitory Activity ◽  
Active Sites ◽  
Point Mutations ◽  
List Type ◽  
Wild Type ◽  
Monocyte Activation ◽  
Cc Chemokine ◽  
Plaque Growth

Background: Chemokines bind to glycosaminoglycans (GAGs) forming gradients that direct inflammatory cell invasion. The viral chemokine modulating protein (CMP), MT-7 binds the C terminal, GAG-binding domain of chemokines and has been previously reported to significantly reduce cell invasion and plaque growth in rat aortic and renal transplant models. Two other viral CMPs, M-T1 and M3 CMPs bind the N terminal domain of chemokines that bind to cell surface receptors. To determine the role of CC chemokine receptor 2 (CCR2) and GAGs for M-T7 anti-inflammatory activity, effects of M-T7 on plaque growth were assessed after mouse CCR2 deficient (CCR2−/−) or GAG deficient (NDST1−/−) aortic allograft transplant. Mononuclear cell migration in response to MCP-1 or RANTES into mouse ascites was also tested. Active sites necessary for M-T7 inhibition of chemokine function and monocyte activation, were assessed by infusion of in the mouse cell migration and human monocyte membrane fluidity assays. Results: M-T7 significantly reduced cell migration and intimal hyperplasia in wild type CCR2+/+ (p<0.009), and CCR2−/− aortic transplants (p<0.026). M-T1 and M3 inhibited cell invasion and plaque in CCR2+/+, but not CCR2−/− mice. M-T7 inhibited plaque growth and CC chemokine (MCP-1 and RANTES)-induced cell migration in wild type mice (P<0.01), but not in NDST1−/− mice (P=0.34). Selected M-T7 point mutations Ty (Y)46A, and Val (V) 210A no longer block chemokine-induced cell migration nor monocyte activation, whereas Asn (N) 40, Asn (N) 63 and Val (V)129 retain inhibitory activity. Conclusions: M-T7 but not M-T1 nor M3, blocks cell migration and plaque growth in CCR2 deficient (CCR2−/−) mouse aortic transplant models. M-T7 loses the ability to block cell migration and plaque growth in NDST1−/−, GAG (heparan sulfate) deficient mice. Point mutations Tyr46 and Val 210 lack inflammatory for mouse and human inflammatory monocyte responses indicating that these amino acid residues on the M-T7 CMP protein are required for inhibitory activity.

SV40-transformed hamster cells resistant to 100–250 microgram/ml of ethidium bromide

1978 ◽  
Vol 33 (1) ◽  
pp. 157-169
Author(s):  
G. Wolf ◽  
L. Tejmar ◽  
S. Borell ◽  
W. Klietman
Keyword(s):  
Mitochondrial Dna ◽  
Cell Lines ◽  
Ethidium Bromide ◽  
Gel Electrophoresis ◽  
Mitochondrial Proteins ◽  
Wild Type ◽  
Mitochondrial Ultrastructure ◽  
Gold Hamsters ◽  
Resistant Cells

SV40-transformed hamster cells were selected for resistance to ethidium bromide (EB). Several cell lines were established, which grew in the presence of up to 250 microgram/ml EB. The EB resistance is genetically stable. The cloned resistant cells show no difference in morphology, with the exception of the mitochondrial ultrastructure, which exhibits condensed cristae formation. The tumorigenicity of these cells in Syrian gold hamsters is considerably reduced. Incorporation of radioactive labelled thymidine into mitochondrial DNA is not influenced by the presence of the drug. Gel electrophoresis with mitochondrial proteins from wild-type and resistant cells reveals significantly different patterns. The mechanism of EB resistance is discussed.

scholarly journals The receptor tyrosine kinase p185HER2 is expressed on a subset of B- lymphoid blasts from patients with acute lymphoblastic leukemia and chronic myelogenous leukemia

Blood ◽  
1995 ◽  
Vol 86 (5) ◽  
pp. 1916-1923 ◽  
Author(s):  
HJ Buhring ◽  
I Sures ◽  
B Jallal ◽  
FU Weiss ◽  
FW Busch ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Tyrosine Kinase ◽  
Cell Lines ◽  
Receptor Tyrosine Kinase ◽  
Lymphoblastic Leukemia ◽  
Blast Crisis ◽  
Hematopoietic Cell ◽  
Myelogenous Leukemia ◽  
Leukemic Cells ◽  
B Lymphoid

The class I receptor tyrosine kinase (RTK) HER2 is an oncoprotein that is frequently involved in the pathogenesis of tumors of epithelial origin. Here we report mRNA expression in peripheral blood and bone marrow cells from healthy donors in hematopoietic cell lines and leukemic blasts from patients with acute lymphoblastic leukemia (ALL), acute myeloblastic leukemia (AML), chronic lymphoblastic leukemia (CLL), and chronic myeloid leukemia (CML). However, cell surface expression of HER2 protein (p185HER2) was found exclusively on a subset of leukemic cells of the B-lymphoblastic lineage. p185HER2 expression was found on blasts in 2 of 15 samples from infants, 9 of 19 samples from adult patients with C-ALL (CD19+CD10+), and 1 of 2 samples from patients with pro-B ALL (CD19+CD10-), whereas none of the leukemic cells from patients with AML (0/30), T-ALL (0/7), CLL (0/5) (CD19+CD5+), or CML in chronic and accelerated phase (0/5) or in blast crisis with myeloid differentiation (0/14) were positive for p185HER2. However, cells from 3 of 4 patients with CML in B-lymphoid blast crisis (CD19+CD10+) expressed high levels of p185HER2, which was also found on the surface of the CML-derived B-cell lines BV-173 and Nalm-1. Our study shows p185HER2 expression on malignant cells of hematopoietic origin for the first time. Aberrant expression of this oncogenic receptor tyrosine kinase in hematopoietic cell types may be an oncogenic event contributing to the development of a subset of B- lymphoblastic leukemias.

scholarly journals Mutation of the p53 gene in human acute myelogenous leukemia

Blood ◽  
1991 ◽  
Vol 77 (7) ◽  
pp. 1500-1507 ◽  
Author(s):  
JM Slingerland ◽  
MD Minden ◽  
S Benchimol
Keyword(s):  
Acute Myelogenous Leukemia ◽  
P53 Protein ◽  
Point Mutations ◽  
P53 Gene ◽  
Myelogenous Leukemia ◽  
Wild Type ◽  
P53 Expression ◽  
Coding Sequence ◽  
Acute Myelogenous ◽  
Blast Cells

Abstract Heterogeneity of p53 protein expression is seen in blast cells of patients with acute myelogenous leukemia (AML). p53 protein is detected in the blasts of certain AML patients but not in others. We have identified p53 protein variants with abnormal mobility on gel electrophoresis and/or prolonged half-life (t 1/2). We have sequenced the p53 coding sequence from primary blast cells of five AML patients and from the AML cell line (OCIM2). In OCIM2, a point mutation in codon 274 was identified that changes a valine residue to aspartic acid. A wild type p53 allele was not detected in these cells. Two point mutations (codon 135, cysteine to serine; codon 246, methionine to valine) were identified in cDNA from blasts of one AML patient. Both mutations were present in blast colonies grown from single blast progenitor cells, indicating that individual leukemia cells had sustained mutation of both p53 alleles. The cDNAs sequenced from blast samples of four other patients, including one with prolonged p53 protein t 1/2 and one with no detectable p53 protein, were fully wild type. Thus, the heterogeneity of p53 expression cannot be explained in all cases by genetic change in the p53 coding sequence. The prolonged t 1/2 of p53 protein seen in some AML blasts may therefore reflect changes not inherent to p53. A model is proposed in which mutational inactivation of p53, although not required for the evolution of neoplasia, would confer a selective advantage, favoring clonal outgrowth during disease progression.

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