scholarly journals Pre-Clinical Evaluation of the Proteasome Inhibitor Ixazomib against Bortezomib-Resistant Leukemia Cells and Primary Acute Leukemia Cells

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 665
Author(s):  
Margot S.F. Roeten ◽  
Johan van Meerloo ◽  
Zinia J. Kwidama ◽  
Giovanna ter Huizen ◽  
Wouter H. Segerink ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Cell Lines ◽  
Proteasome Inhibitor ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Unmet Need ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Cross Resistance ◽  
Proteasome Subunit

At present, 20–30% of children with acute leukemia still relapse from current chemotherapy protocols, underscoring the unmet need for new treatment options, such as proteasome inhibition. Ixazomib (IXA) is an orally available proteasome inhibitor, with an improved safety profile compared to Bortezomib (BTZ). The mechanism of action (proteasome subunit inhibition, apoptosis induction) and growth inhibitory potential of IXA vs. BTZ were tested in vitro in human (BTZ-resistant) leukemia cell lines. Ex vivo activity of IXA vs. BTZ was analyzed in 15 acute lymphoblastic leukemia (ALL) and 9 acute myeloid leukemia (AML) primary pediatric patient samples. BTZ demonstrated more potent inhibitory effects on constitutive β5 and immunoproteasome β5i proteasome subunit activity; however, IXA more potently inhibited β1i subunit than BTZ (70% vs. 29% at 2.5 nM). In ALL/AML cell lines, IXA conveyed 50% growth inhibition at low nanomolar concentrations, but was ~10-fold less potent than BTZ. BTZ-resistant cells (150–160 fold) displayed similar (100-fold) cross-resistance to IXA. Finally, IXA and BTZ exhibited anti-leukemic effects for primary ex vivo ALL and AML cells; mean LC50 (nM) for IXA: 24 ± 11 and 30 ± 8, respectively, and mean LC50 for BTZ: 4.5 ± 1 and 11 ± 4, respectively. IXA has overlapping mechanisms of action with BTZ and showed anti-leukemic activity in primary leukemic cells, encouraging further pre-clinical in vivo evaluation.

scholarly journals Dynamin inhibition causes context-dependent cell death of leukemia and lymphoma cells

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0256708
Author(s):  
Christopher von Beek ◽  
Linnéa Alriksson ◽  
Josefine Palle ◽  
Ann-Marie Gustafson ◽  
Mirjana Grujic ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Death ◽  
Acute Leukemia ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cell ◽  
Tumor Formation ◽  
Leukemia Cells ◽  
Human Leukemia ◽  
Bone Marrow Biopsies

Current chemotherapy for treatment of pediatric acute leukemia, although generally successful, is still a matter of concern due to treatment resistance, relapses and life-long side effects for a subset of patients. Inhibition of dynamin, a GTPase involved in clathrin-mediated endocytosis and regulation of the cell cycle, has been proposed as a potential anti-cancer regimen, but the effects of dynamin inhibition on leukemia cells has not been extensively addressed. Here we adopted single cell and whole-population analysis by flow cytometry and live imaging, to assess the effect of dynamin inhibition (Dynasore, Dyngo-4a, MitMAB) on pediatric acute leukemia cell lines (CCRF-CEM and THP-1), human bone marrow biopsies from patients diagnosed with acute lymphoblastic leukemia (ALL), as well as in a model of lymphoma (EL4)-induced tumor growth in mice. All inhibitors suppressed proliferation and induced pronounced caspase-dependent apoptotic cell death in CCRF-CEM and THP-1 cell lines. However, the inhibitors showed no effect on bone marrow biopsies, and did not prevent EL4-induced tumor formation in mice. We conclude that dynamin inhibition affects highly proliferating human leukemia cells. These findings form a basis for evaluation of the potential, and constraints, of employing dynamin inhibition in treatment strategies against leukemia and other malignancies.

Amplification and Mutation of PSMB5 Gene in Bortezomib Resistant Lymphoblastic Leukemia Cells Derived from Jurkat Line.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2373-2373 ◽  
Author(s):  
Shuqing Lu ◽  
Jianmin Wang ◽  
Jianmin Yang ◽  
Shenglan Gong ◽  
Hong Zhou ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Binding Affinity ◽  
Quantitative Pcr ◽  
Cell Lines ◽  
Proteasome Inhibitor ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cell ◽  
Jurkat Cells ◽  
Cross Resistance ◽  
Leukemia Cell Lines

Abstract Bortezomib, the first selective proteasome inhibitor in this new category of anti-cancer drug, inhibits chymotrypsin-like activity sited at beta 5 subunit of proteasome (PSMB5). To study the mechanism of proteasome inhibitor resistance in tumor cells, we established a series of bortezomib resistant lymphoblastic leukemia cell lines, named JurkatBs, from Jurkat line by repeated drug induction. There were no significant differences observed in the growth curves, colony formation rates, or cell cycle distribution between the JurkatBs and Jurkat cells. However, the effects of bortezomib, namely cytotoxicity, cell cycle arrest at G2 phase and induction of apoptosis, were decreased significantly in JurkatBs cells. There were no significant differences of intracellular mean fluorescence intensities of daunorubicin between JurkatBs and Jurkat cells (P>0.05) after treated with daunorubicin. Accordingly, the JurkatBs showed no cross-resistance to anthracycline, alkaloid and topoisomerase inhibitor. Quantitative PCR analysis showed no significant overexpression of MDR1 gene in JurkatB1, JurkatB2, JurkatB5 cells in comparison with that of Jurkat cells (22.77±5.58, 1.17±0.23, 8.30±2.62 vs 1.00±0.50; P>0.05). P-gp expression analysis was also negative in JurkatBs and Jurkat cells by Western bloting. By using quantitative PCR, we found that the PSMB5 gene was significantly amplified in JurkatB1 (5.82±0.60) and JurkatB5 cells (6.78±1.21) in comparison with that of Jurkat cells (1±0.49)(P<0.001), but not in JurkatB2 cells(0.16±0.03, P=1.000). A specific chromosome abnormality, i(14q), was found in all JurkatB5 cells (highly resistant to bortezomib), 4/16 JurkatB1 cells (moderately resistant), but not in JurkatB2 cells (slightly resistant). This results suggested that i(14q) may be resulted from the amplification of PMSB5 gene, which is located at 14q11. The chymotrypsin-like activities, determined by measuring the release of the fluorescent AMC from the substrate N- Suc-Leu-Leu-Val- Tyr-AMC, increased significantly in JurkatB1 (relative activity 3.27±0.12) and JurkatB5 cells (5.75±0.22) in comparison with that in Jurkat cells (1.00±0.14; P<0.001), but not in JurkatB2 cells (0.92±0.09; P>0.05). These results were coincident with the amplication of PSMB5, which may partly elucidated the bortezomib resistance in JurkatB cells. We then cloned and sequenced the full-length cDNA product of the PSMB5 gene from JurkatBs and Jurkat cells. A mutation at position 322 (G322A) of PSMB5 gene, causing an an amino acid substitution (Ala108Thr), was found in all selected JurkatB clones. The inhibition of chymotrypsin-like activities in JurartB2 (39.66±2.89) and JurartB5 cells (1.71±3.51), incubated with 10nM bortezomib up to 18h, were decreased significantly in comparison with that of Jurkat cells (86.87±0.97; P<.001), suggesting a decreased binding affinity of bortezomib to the chymotrypsin-like active site caused by Ala108Thr in JurkatB cells, which may resulted in conformation change in β5 subunit. In conclusion, we established bortezomib resistant leukemia cell lines with a different mechanism from that of multi-drug resistance (MDR). Both amplification and G322A mutation of PSMB5 gene are the important mechanisms of bortezomib resistance, by increasing chymotrypsin-like activity, and decreasing binding affinity of bortezomib to the chymotrypsin-like site, respectively.

Metabolic Profile Of Leukemia Cells Influences Treatment Efficacy Of L‑Asparaginase

2019 ◽  
Author(s):  
Katerina Hlozkova ◽  
Alena Pecinova ◽  
David Pajuelo Reguera ◽  
Marketa Simcikova ◽  
Lenka Hovorkova ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Cell Lines ◽  
Mitochondrial Membrane ◽  
Metabolic Profile ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Lower Sensitivity ◽  
Leukemia Cell Lines

Abstract Background Effectiveness of L-asparaginase administration in acute lymphoblastic leukemia treatment is mirrored in overall outcome of patients. Generally, leukemia patients differ in their sensitivity to L-asparaginase; however, the mechanism underlying their inter-individual differences is still not fully understood. We have previously shown that L-asparaginase rewires the biosynthetic and bioenergetic pathways of leukemia cells to activate both anti-leukemic and pro-survival processes. Herein, we investigated the relationship between the metabolic profile of leukemia cells and their sensitivity to currently used cytostatic drugs.Methods Altogether, 19 leukemia cell lines and primary leukemia cells from 11 patients were used. Glycolytic function and mitochondrial respiration were measured using Seahorse bioanalyzer. Sensitivity to cytostatics was measured using MTS assay and/or absolute count and flow cytometry. Mitochondrial membrane potential was determined as TMRE fluorescence.Results We characterized the basal metabolic state of the cells derived from different leukemia subtypes using cell lines and primary samples and assessed their sensitivity to cytostatic drugs. We found that leukemia cells cluster into distinct groups according to their metabolic profile, which is mainly driven by their hematopoietic lineage of origin from which they derived. However, majority of lymphoid leukemia cell lines and patients with lower sensitivity to L-asparaginase clustered regardless their hematopoietic phenotype together with myeloid leukemias. Furthermore, we observed a correlation of specific metabolic parameters with sensitivity to L-asparaginase. Greater ATP-linked respiration and lower basal mitochondrial membrane potential in cells significantly correlated with higher sensitivity to L-asparaginase. No such correlation was found in other tested cytostatic drugs.Conclusions These data support the prominent role of the cell metabolism in the treatment effect of L-asparaginase. Based on these findings metabolic profile could identify leukemia patients with lower sensitivity to L-asparaginase with no specific genetic characterization.

Sensitivity of Pediatric Acute Leukemia Cells to Bortezomib and Epoxyketone-Based Proteasome Inhibitors: Correlations with Proteasome Subunit Expression

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1513-1513
Author(s):  
Denise Niewerth ◽  
Niels Franke ◽  
Gerrit Jansen ◽  
Johan van Meerloo ◽  
Yehuda Assaraf ◽  
...  
Keyword(s):  
Second Generation ◽  
Lymphoblastic Leukemia ◽  
Proteasome Inhibitors ◽  
Differential Sensitivity ◽  
Leukemia Cells ◽  
Cross Resistance ◽  
Pediatric Leukemia ◽  
Proteasome Subunit ◽  
Subunit Expression ◽  
Proteasome Subunits

Abstract Abstract 1513 Good response to glucocorticoids (GC) has favorable prognostic value for the survival of children with acute lymphoblastic leukemia (ALL). Hence, GC-resistant and relapsed ALL patients may benefit from GC-sensitization strategies. For this purpose, the reversible proteasome inhibitor (PI) Bortezomib (BTZ) is currently being evaluated in clinical trials in combination with Dexamethasone (DEX) and other drugs. Despite the encouraging results of BTZ in several hematological malignancies, emergence of resistance to BTZ may be a limiting factor to its efficacy. Therefore, the aim of our study was to examine the differential sensitivity of pediatric leukemia cells to BTZ and DEX, as compared to second generation PIs designed to overcome BTZ resistance. These include the epoxyketone-based irreversibly binding PIs Carfilzomib (CFZ), its orally bioavailable analog ONX 0912, and the immunoproteasome inhibitor ONX 0914. The drug concentration required for 50% cell death (LC50) was determined in pediatric patient samples (29 ALL and 12 AML) after 4 days drug exposure using the MTT cytotoxicity assay. Furthermore, the sensitivity to PIs was correlated with protein expression levels of the constitutive proteasome subunits beta5, beta1 and beta2, and the (immuno) proteasome subunits beta5i and beta1i. ALL cells were significantly more sensitive for BTZ than AML cells (median LC50: 6.0 nM vs 14.2 nM, respectively, p=0.002), and also markedly more sensitive to Dex (median LC50: 23.0 nM vs. >600 nM, p<0.001). Sensitivity profiles for the PIs CFZ, ONX 0912 and ONX 0914 are presented in Table 1. Collectively, ALL cells were significantly more sensitive than AML cells for all these 3 PIs with irreversible binding properties. LC50 concentrations for CFZ were comparable to those of BTZ. In descending order, ONX 0912 and ONX 0914 displayed lower potencies than BTZ/CFZ, but LC50 concentrations were still in the low nanomolar range.Table 1.Difference in in vitro sensitivity to proteasome inhibitors and proteasome subunit expression between pediatric ALL and AML patientsAcute Lymphoblastic LeukemiaAcute Myeloid LeukemiaANOVA p-valueNMedian LC50 (nM)RangeNMedian LC50 (nM)RangeDrugs    BTZ296.03.0–46.11114.210.1–61.00.002    CFZ274.10.08–8.71020.86.0–30.80.000    ONX 09122719.27.6–80.91093.755.7–3940.000    ONX 09142744.68.4–1171024889.2–6780.000    DEX2723.00.50–>60012600.0164–>6000.000Subunit expressionRatio*Ratio*    beta5280.760.00–30.0106.02.2–23.90.080    beta5i2762.58.5–3661055.010.6–3400.714    beta1282.40.00–28.11011.70.92–26.10.029    beta1i2835.15.42–1061017.77.2–49.50.032    beta2284.80.38–23.41020.47.4–39.10.000    beta2iN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.: Not Determined. * Ratio proteasome subunit / β-actin based on loading of 15 ug total protein (Western blot analysis) For ALL, LC50 concentrations for CFZ and ONX 0912 were significantly correlated (r=0.449, p=0.019). Interestingly, for AML, a significant correlation was observed between BTZ and CFZ LC50 concentrations (r=0.900, p=0.001), suggestive for overlapping activities. Expression of constitutive proteasome subunits is higher in AML cells than ALL cells. Within ALL samples, constitutive proteasome subunit expression did not correlate with LC50 concentrations for each of the PIs. Within AML patients, however, beta 5 expression significantly correlated with BTZ LC50 (r=0.980, p<0.001). A trend towards a significant correlation was observed for BTZ LC50 and beta 1 (r=0.550, p=0.125) and beta 2 expression (r=0.500, p=0.17). Next, LC50 concentrations of CFZ correlated significantly with beta 5 (r=0.783, p=0.013) and beta 1 (r=0.817, p=0.007) expression. Finally, both in ALL and AML samples, no correlations were revealed for immunoproteasome subunits expression and LC50 concentrations for BTZ, CFZ, ONX 0912 and ONX 0914. In conclusion, ALL cells were more sensitive to PIs than AML, which may be due lower constitutive proteasome unit expression. Pediatric leukemia cells display marked sensitivity to BTZ and second generation PIs, but lack cross-resistance between BTZ and several second generation PIs. Together, for second generation PIs, these data may hold promise for circumvention of BTZ resistance and further exploration of efficacy assessments in combination with other drugs, in particular GCs. Disclosures: No relevant conflicts of interest to declare.

Uncovering Cardioprotective Strategies For Anthracycline Therapy By Analysis Of Redox and Apoptotic Effects

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1293-1293
Author(s):  
Daniela E. Egas Bejar ◽  
Joy M. Fulbright ◽  
Fernando F. Corrales-Medina ◽  
Mary E. Irwin ◽  
Blake Johnson ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Vitamin E ◽  
Acute Leukemia ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Cell Types ◽  
Leukemia Cells ◽  
Soluble Form ◽  
Leukemia Cell Lines

Abstract Anthracyclines are among the most powerful drugs used for the treatment of leukemia, however their use has been associated with cardiotoxicity. Reactive oxygen species (ROS) are generated in both cancer and normal cells after anthracycline exposure and have been implicated in both early and late onset cardiotoxicity. Counteracting this ROS generation are intracellular antioxidants such as the ubiquitous antioxidant glutathione (GSH), levels of which are depleted upon anthracycline exposure. Basal expression of GSH pathway components and other antioxidants vary greatly between different cell types. Due to this differential expression of cellular antioxidants in cardiomyocytes versus leukemia cells, we posit that anthracyclines exert distinct effects on oxidative stress and consequent apoptosis induction in leukemia cells and nontransformed hematopoietic cells (PBMC) relative to cardiomyocytes. As a result, we expect potentially varied mechanisms of cell death induction in these cell lines after anthracycline treatment. To test this hypothesis, the acute leukemia cell lines Jurkat and ML-1 and the cardiomyocyte line H9C2 were used. Dose responses with the anthracyclines, doxorubicin and daunorubicin, were carried out and trypan blue exclusion and propidium iodide staining followed by flow cytometry were used to assess viability and DNA fragmentation respectively. Cardiomyocytes had a 25-150 fold higher IC50 value than the acute leukemia cell lines, indicating selectivity. To assess whether apoptosis was induced by anthracyclines, caspase 3 activity was measured and found to be increased at 24 hours in Jurkat cells which preceded decreases in viability, supporting an apoptotic mechanism of cell death. GSH levels also decreased markedly after 24 hours of treatment with anthracyclines in this cell line, however, a pan-caspase inhibitor did not block GSH depletion, indicating that these events occur independent of each other. To evaluate whether antioxidants conferred protection against loss of viability in all cell types, cells were pretreated for at least 30 minutes with antioxidants and then treated with doxorubicin and daunorubicin for 24 hours. Antioxidants used were N-acetylcysteine (NAC, a GSH precursor and amino acid source), GSH ethyl ester (cell permeable form of GSH), tiron (free radical scavenger) and trolox (a water soluble form of vitamin E). GSH ethylester did not prevent cytotoxicity of anthracyclines in acute leukemia lines or cardiomyocytes. Therefore boosting GSH levels in leukemia cells does not reverse cytotoxicity. Trolox, however, did block anthracycline induced cell death in ML-1 cells, suggesting that vitamin E supplementation would counteract leukemia cell specific effects of anthracyclines on AML cells. Tiron protected PBMC from doxorubicin cytotoxicity but did not protect leukemia cells or cardiomyocytes, hinting at a protective strategy for normal non-leukemia blood cells. Interestingly, NAC did not interfere with the cytotoxic effects of anthracyclines on acute leukemia cells or PBMC, but protected H9C2 cells from daunorubicin cytotoxicity. Taken together, these data reveal differential protective effects of antioxidants in cardiomyocytes and PBMCs relative to ALL and AML cells. Our work indicates that NAC can protect cardiomyocytes without interfering with anthracycline cytotoxicity in acute leukemia cells. In humans, one randomized control trial tested the addition of NAC to doxorubicin therapy, detecting no evidence of cardioprotective activity by chronic administration of NAC. However, the schedule used for administration of NAC in that study may not have been optimal, and biomarkers for oxidative stress reduction by NAC were not incorporated into the trial. Previously, other antioxidants have been used with very limited clinical success and possible contributing factors include inadequate sample size, choice of agent, dose used, duration of intervention and the lack of biomarker endpoints. Designing a cardioprotective and antioxidant strategy with attention to these factors may prove to be efficacious in protecting cardiac cells without interfering with the antitumoral effect of anthracyclines. To this end, our data suggests that trolox and vitamin E analogues should not be used in acute leukemia as they may interfere with the cytotoxic action of anthracyclines but NAC or cysteine may be used as cardioprotectants. Disclosures: No relevant conflicts of interest to declare.

Gene Delivery to Human B-Precursor Acute Lymphoblastic Leukemia Cells

Blood ◽  
1998 ◽  
Vol 92 (10) ◽  
pp. 3537-3545 ◽  
Author(s):  
Leo Mascarenhas ◽  
Renata Stripecke ◽  
Scott S. Case ◽  
Dakun Xu ◽  
Kenneth I. Weinberg ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Gene Transfer ◽  
Gene Delivery ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Leukemia Virus ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Reh Cells ◽  
Hiv 1

Autologous leukemia cells engineered to express immune-stimulating molecules may be used to elicit antileukemia immune responses. Gene delivery to human B-precursor acute lymphoblastic leukemia (ALL) cells was investigated using the enhanced green fluorescent protein (EGFP) as a reporter gene, measured by flow cytometry. Transfection of the Nalm-6 and Reh B-precursor ALL leukemia cell lines with an expression plasmid was investigated using lipofection, electroporation, and a polycationic compound. Only the liposomal compound Cellfectin showed significant gene transfer (3.9% to 12% for Nalm-6 cells and 3.1% to 5% for Reh cells). Transduction with gibbon-ape leukemia virus pseudotyped Moloney murine leukemia virus (MoMuLV)-based retrovirus vectors was investigated in various settings. Cocultivation of ALL cell lines with packaging cell lines showed the highest transduction efficiency for retroviral gene transfer (40.1% to 87.5% for Nalm-6 cells and 0.3% to 9% for Reh cells), followed by transduction with viral supernatant on the recombinant fibronectin fragment CH-296 (13% to 35.5% for Nalm-6 cells and 0.4% to 6% Reh cells), transduction on human bone marrow stroma monolayers (3.2% to 13.3% for Nalm-6 cells and 0% to 0.2% Reh cells), and in suspension with protamine sulfate (0.7% to 3.1% for Nalm-6 cells and 0% for Reh cells). Transduction of both Nalm-6 and Reh cells with human immunodeficiency virus–type 1 (HIV-1)–based lentiviral vectors pseudotyped with the vesicular stomatitis virus-G envelope produced the best gene transfer efficiency, transducing greater than 90% of both cell lines. Gene delivery into primary human B-precursor ALL cells from patients was then investigated using MoMuLV-based retrovirus vectors and HIV-1–based lentivirus vectors. Both vectors transduced the primary B-precursor ALL cells with high efficiencies. These studies may be applied for investigating gene delivery into primary human B-precursor ALL cells to be used for immunotherapy.

scholarly journals Altered Formation of Topotecan-Stabilized Topoisomerase I-DNA Adducts in Human Leukemia Cells

Blood ◽  
1997 ◽  
Vol 89 (6) ◽  
pp. 2098-2104 ◽  
Author(s):  
Scott H. Kaufmann ◽  
Phyllis A. Svingen ◽  
Steven D. Gore ◽  
Deborah K. Armstrong ◽  
Yung-Chi Cheng ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Dna Adducts ◽  
Topoisomerase I ◽  
Ex Vivo ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Clinical Samples ◽  
Human Leukemia ◽  
Leukemia Cell Lines ◽  
Myelomonocytic Leukemia

Abstract Topotecan (TPT) is a topoisomerase I (topo I) poison that has shown promising antineoplastic activity in solid tumors and acute leukemia. In the present study, a band depletion assay was used to evaluate the ability of TPT to stabilize topo I-DNA adducts in human leukemia cell lines and in clinical leukemia samples ex vivo. This assay showed that 50% of the cellular topo I in HL-60 human myelomonocytic leukemia cells became covalently bound to DNA at an extracellular TPT concentration of 4 μmol/L. In contrast, in 13 clinical specimens of human leukemia harvested before treatment of patients with TPT, the TPT concentration required to stabilize 50% of the cellular topo I in topo I-DNA complexes ranged from 3 to greater than 100 μmol/L (median, 30 μmol/L). Flow microfluorimetry showed that cellular TPT accumulation varied over only a twofold range and failed to provide evidence for transport-mediated resistance in the clinical samples. These observations raise the possibility that formation of topo I-DNA adducts is diminished in many specimens of refractory/relapsed acute leukemia by a mechanism that might alter topo I sensitivity to TPT.

scholarly journals Targeting Mutant p53 in Pediatric Acute Lymphoblastic Leukemia

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 903-903
Author(s):  
Salih Demir ◽  
Galina Selivanova ◽  
Eugen Tausch ◽  
Lisa Wiesmüller ◽  
Stephan Stilgenbauer ◽  
...  
Keyword(s):  
Cell Death ◽  
Acute Lymphoblastic Leukemia ◽  
High Risk ◽  
Cell Lines ◽  
Therapeutic Intervention ◽  
High Performance ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cell ◽  
Therapy Resistance ◽  
Leukemia Cells

Abstract Mutations of the tumor suppressor gene TP53 have been described to be associated with aggressive disease and inferior prognosis in different types of cancer, including hematological malignancies. In acute lymphoblastic leukemia (ALL), TP53 alterations are infrequently found at diagnosis but have recently been described in about 12% of patients at relapse. This suggests an association with therapy resistance in high risk/relapsed ALL and patients with TP53 mutated ALL have in fact an inferior outcome. Small molecule compounds targeting mutated TP53 such as APR-246, initially described as PRIMA-1MET (p53-dependent reactivation and induction of massive apoptosis) leading to apoptosis induction have shown activity in several types of malignancies with mutated TP53. In ALL, however, mutant TP53 has so far not been addressed as a target for therapeutic intervention. In this study, we investigated a large cohort of patient-derived pediatric B cell precursor (BCP)-ALL primograft samples to identify cases with mutated TP53. Further, we analyzed the effects of APR-246 and evaluated its activity on BCP-ALL cell lines and primografts with mutated (mut) orwild type (wt) TP53. Altogether, 62 BCP-ALL primograft samples established from patients at diagnosis (n=53) or relapse (n=9) by transplantation of primary ALL cells onto NOD/SCID mice were screened for TP53 mutations by denaturating high-performance liquid chromatography (dHPLC) followed by Sanger sequencing of exons 4 to 10 to confirm detected mutations. We identified 4 cases with TP53 mut, 3 obtained from diagnosis (5.6%) and one at relapse (11.1%), corresponding to frequencies described in clinical studies. Mutated cases were further analyzed by fluorescence in situ hybridization (FISH), revealing a 17p deletion in one TP53 mut sample. Similarly, we analyzed 6 BCP-ALL cell lines and identified 2 TP53 mut and 4 TP53 wt lines. Exposure of BCP-ALL primograft (TP53 mut n=4, TP53 wt n=4) and cell line (TP53 mut n=2, TP53 wt n=4) samples to the DNA damaging agent doxorubicin showed, as expected, resistance of TP53 mut leukemia cells for cell death induction, reflected by significantly higher half maximal inhibitory concentrations (IC50; TP53 mut 49 and 143 ng/ml, TP53 wt mean 12 ng/ml) and lower induction of cell death (TP53 mut 16 to 23%, TP53 wt 10 to 60%) in TP53 mut ALL, corroborating the tumor-suppressive function of p53 in ALL. We then investigated the sensitivity of BCP-ALL cell lines for cell death induction by APR-246 (kindly provided by Aprea, Stockholm, Sweden). We observed high sensitivity for APR-246 in TP53 mut (IC50: 5 µM for both cell lines) as compared to TP53 wt ALL (mean IC50: 58 µM). DNA fragmentation and Annexin-V/propidium-iodide (PI) positivity revealed apoptosis as mechanism of APR-246 mediated cell death. Reactive oxygen species (ROS) have recently been described to mediate APR-246 induced cell death in multiple myeloma cells. Therefore, we investigated ROS levels by detection of oxidation-specific fluorescence of dichlorodihydrofluorescein diacetate (DCFDA) in ALL cells. Interestingly, ROS quenching by N-acetyl cysteine abolished induction of cell death in TP53 mut but not TP53 wt ALL cells indicating ROS as a mediator of APR-246 induced cell death in TP53 mut ALL. Furthermore, we addressed p53 activation in response to APR-246 by assessing phosphorylation of p53 (p53pSer15) using phosphoflow cytometry. Most interestingly, APR-246 led to 6-fold increased p53pSer15 levels in TP53 mut compared to no activation in TP53 wt leukemia cells, indicating restoration of p53function upon APR-246treatment in BCP-ALL. Based on these findings, we addressed the effectivity of APR-246on primary, patient-derived primografts and compared sensitivities for cell death induction in TP53 mut (n=4) and TP53 wt (n=4) samples. Importantly, the pattern of responsiveness of TP53 mut ALL was also identified in TP53 mut patient-derived ALL samples with induction of significantly higher cell death rates in TP53 mut ALL (TP53 mut 48%, TP53 wt 18%, 5 µM APR-246, 24 h). Taken together, we showed that TP53 mut BCP-ALL can be targeted by APR-246 leading to re-activation of p53, induction of ROS dependent apoptosis and effective leukemia cell killing. Thus, targeting and re-activation of mutated p53 provides a promising novel strategy for therapeutic intervention in this high-risk subtype of BCP-ALL. Disclosures Selivanova: Aprea: Patents & Royalties: APR-246. Tausch:Gilead: Other: Travel support. Stilgenbauer:Gilead: Honoraria, Research Funding.

Single-Cell Phospho-Profiling in Pediatric Acute Lymphoblastic Leukemia (ALL) Reveals Constitutive and Cytokine Induced Specific Signatures Involving Stat5

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2511-2511
Author(s):  
Manon Queudeville ◽  
Hannah Kunze ◽  
Sarah M. Eckhoff ◽  
Klaus-Michael Debatin ◽  
Lueder H. Meyer
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cells ◽  
Single Cell ◽  
B Lymphocytes ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Leukemia Cell Lines ◽  
Significant Difference

Abstract Oncogenesis and tumor progression are supported by alterations in cellular signaling. We used phospho-specific antibodies in flow cytometry to analyze specific signaling profiles of leukemia cells at a single cell level in 7 B cell precursor (BCP)-ALL leukemia cell lines and 7 primary pediatric BCP-ALL xenograft samples. Peripheral blood lymphocytes gated on CD19-positive B cells were used as normal nonmalignant controls. Cells were stimulated by different stimulants and cytokines (PMA, anisomycin, IL-4, IL-6, IL-7, IL-10 and IFN-α) and activation of various phosphoepitopes (pERK, pp38, pJNK, pStat1, pStat3, pStat5, pStat6) was analyzed and compared to the basal state of unstimulated samples. Signaling profiles of normal B-lymphocytes were compared to those of the BCPALL cell lines as well as to the BCP-ALL xenograft samples. Significance of differences was assessed by the nonparametric Mann-Whitney U-test. Basal phosphorylation was significantly higher in the leukemia cell lines than in normal lymphocytes. Similarly, basal phosphorylation of all analyzed epitopes in xenografts exceeded the phosphorylation state of normal B-lymphocytes (with the exception of p38 phosphorylation, where there was no significant difference). Interestingly, the BCP-leukemia cell lines also had significantly higher basal phosphorylation levels than the primary BCP-ALL xenografts. However, when comparing the amounts of phosphorylation before and after stimulation mature normal B-cells displayed significantly higher profiles compared to the leukemia cell lines e.g. for pp38 and pJNK after stimulation with PMA (P= .001), for pStat3 after stimulation with IL-6 (P= .002) and IL-10 (P= .037) and for pStat6 (P= .001) after stimulation with IL-4. Conversely, the leukemia cell lines showed increased phosphorylation of p38 after stimulation with anisomycin (P= .021) as well as higher Stat5 phosphorylation after stimulation with IL-7 (P= .021) compared to normal lymphocytes. In normal B-cells compared to xenografts higher levels were found after stimulation with PMA for pp38 (P= .007), for pJNK after PMA stimulation (P= .001), for pStat3 after IL-6 (P=.003) and for pStat6 after IL-4 (P= .002) stimulation while the xenograft samples displayed stronger reaction to stimulation with anisomycin for pp38 (P= .037) and to stimulation with IL-7 for pStat5 (P= .028). The level of phosphorylation after treatment with different stimulants in the xenografted leukemia samples was similar to that of the leukemia cell lines although the cell lines displayed higher basal phosphorylation values. The BCP-leukemia cell lines and the BCP xenograft samples both displayed high levels of constitutive phosphorylation in general reducing their ability to react to a given stimulus compared to normal B-lymphocytes. With the most important exception of Stat5: we consistently found that Stat5 phosphorylation is increased in acute lymphoblastic leukemia cell lines and primary xenografts after stimulation with IL-7 compared to normal B-lymphocytes. Stat5 is known to enhance proliferation and protect from apoptosis and our data now strongly suggest that Stat5 and Stat5 dependent pathways are critically involved in leukemogenesis. Since we could identify significant and specific phosphorylation signatures characteristic for leukemia cells, this provides a strategy to define pathways important for continued survival, proliferation and resistance of leukemia and allows identification of therapeutic targets and novel biomarkers associated with clinical outcome.

Small molecule XIAP inhibitors cooperate with TRAIL to induce apoptosis in childhood acute leukemia cells and overcome Bcl-2–mediated resistance

Blood ◽  
2009 ◽  
Vol 113 (8) ◽  
pp. 1710-1722 ◽  
Author(s):  
Melanie Fakler ◽  
Sandra Loeder ◽  
Meike Vogler ◽  
Katja Schneider ◽  
Irmela Jeremias ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Small Molecule ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cells ◽  
Dependent Manner ◽  
Apoptosis Resistance ◽  
Childhood All ◽  
Normal Peripheral Blood ◽  
Childhood Acute Leukemia

Abstract Defects in apoptosis contribute to poor outcome in pediatric acute lymphoblastic leukemia (ALL), calling for novel strategies that counter apoptosis resistance. Here, we demonstrate for the first time that small molecule inhibitors of the antiapoptotic protein XIAP cooperate with TRAIL to induce apoptosis in childhood acute leukemia cells. XIAP inhibitors at subtoxic concentrations, but not a structurally related control compound, synergize with TRAIL to trigger apoptosis and to inhibit clonogenic survival of acute leukemia cells, whereas they do not affect viability of normal peripheral blood lymphocytes, suggesting some tumor selectivity. Analysis of signaling pathways reveals that XIAP inhibitors enhance TRAIL-induced activation of caspases, loss of mitochondrial membrane potential, and cytochrome c release in a caspase-dependent manner, indicating that they promote a caspase-dependent feedback mitochondrial amplification loop. Of note, XIAP inhibitors even overcome Bcl-2–mediated resistance to TRAIL by enhancing Bcl-2 cleavage and Bak conformational change. Importantly, XIAP inhibitors kill leukemic blasts from children with ALL ex vivo and cooperate with TRAIL to induce apoptosis. In vivo, they significantly reduce leukemic burden in a mouse model of pediatric ALL engrafted in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. Thus, XIAP inhibitors present a promising novel approach for apoptosis-based therapy of childhood ALL.

Sign in / Sign up

Export Citation Format

Share Document