scholarly journals TRIM31 promotes acute myeloid leukemia progression and sensitivity to daunorubicin through the Wnt/β-catenin signaling

2020 ◽  
Vol 40 (4) ◽  
Author(s):  
Yi Xiao ◽  
Taoran Deng ◽  
Xi Ming ◽  
Jinhuang Xu
Keyword(s):  
Cell Proliferation ◽  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Caspase 3 ◽  
Mrna Levels ◽  
Transfected Cells ◽  
Expression Levels ◽  
Acute Myeloid

Abstract Tripartite motif (TRIM) 31 is a member of TRIM family and exerts oncogenic role in the progression and drug resistance of several cancers. However, little is known about the relevance of TRIM31 in acute myeloid leukemia (AML). Herein, we investigated the role of TRIM31 in AML. We examined the expression levels of TRIM31 in the blood samples from 34 patients with AML and 34 healthy volunteers using qRT-PCR. The mRNA levels of TRIM31 in human bone marrow stromal cells (HS-5) and five AML cell lines were also detected. Loss/gain-of-function assays were performed to assess the role of TRIM31 in AML cells proliferation, apoptosis and sensitivity to daunorubicin. The expression levels of pro-caspase 3, cleaved caspase 3, Wnt3a, β-catenin, cyclin D1 and c-Myc were measured using Western blot. TRIM31 expression levels were significantly up-regulated in AML patients and cell lines. Knockdown of TRIM31 suppressed cell proliferation and promoted apoptosis in AML-5 and U937 cells. The IC50 of daunorubicin was significantly decreased in TRIM31 siRNA (si-TRIM31) transfected cells. Oppositely, induced cell proliferation and decreased cell apoptosis were observed in pcDNA-3.1-TRIM31 transfected cells. Furthermore, knockdown of TRIM31 suppressed the activation of Wnt/β-catenin pathway in AML cells. Activation of Wnt/β-catenin pathway by LiCl abolished the effects of si-TRIM31 on cell proliferation, apoptosis and sensitivity to daunorubicin in AML cells. In conclusion, the results indicated that TRIM31 promoted leukemogenesis and chemoresistance to daunorubicin in AML. The oncogenic role of TRIM31 in AML was mediated by the Wnt/β-catenin pathway. Thus, TRIM31 might serve as a therapeutic target for the AML treatment.

Acute Myeloid Leukemia Cells Require STAT5 for Survival.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1616-1616
Author(s):  
Martin Carroll ◽  
Tae Kon Kim ◽  
Kenichi Higashino ◽  
Alan M. Gewirtz
Keyword(s):  
Cell Proliferation ◽  
Acute Myeloid Leukemia ◽  
Cell Survival ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Cytokine Signaling ◽  
Primary Cells ◽  
Stat3 Phosphorylation ◽  
Acute Myeloid

Abstract Signal transducer and activator of transcription (STAT) family proteins play crucial roles in the cytokine signaling pathways which regulate survival and proliferation of normal hematopoietic cells. However, the role of STAT proteins in regulating survival in leukemia remains poorly defined. STAT3 and STAT5, for example, have been reported to be constitutively activated in acute myeloid leukemia (AML) cells, however the physiologic significance of this activation is unknown. In order to better understand the role of STAT3 and STAT5 in AML biology, we studied their expression, activation, and requirement for cell growth in several AML cell lines and primary AML cells collected from patients at the University of Pennsylvania Cancer Center. We first confirmed the activation of STAT3 and STAT5 in primary AML cells by western blotting. An analysis of AML patient samples revealed elevated levels of constitutive STAT3 phosphorylation in 6 of 7 patient samples and constitutive STAT5 phosphorylation in 8 of 9 patient samples. In addition, 6 AML cell lines (K562, HL-60, MOLM-14, U937, KG-1, NB4) displayed constitutive STAT3 and STAT5 activation. In order to evaluate the functional significance of constitutive activation of STAT3 and STAT5 in AML cells, we designed and synthesized short interfering RNAs (siRNAs) to silence the expression of these proteins. For initial characterization, the siRNAs were delivered to MOLM-14 cells using an AMAXA nucleofector device (AMAXA, Inc. Gaithersburg, MD)(Program O-17/Solution V). Nucleofected siRNA diminished STAT3 expression by 85% at 24 hour but had little effect on cell proliferation (13%±3% decrease at 24 hour, 8%±4% at 48 hour, 5%±1% at 72 hour) compared to control siRNA treated cells. In contrast, STAT5 siRNA decreased STAT5 expression 80% at 24 hour compared to control treated cells but inhibited cell proliferation by 19%±1% at 24 hour, 22%±1% at 48 hour, 16%±3% at 72 hour in comparison to control siRNA treated cells suggesting a more important role for STAT5 in regulating cell proliferation. To study the effect of these siRNA molecules in primary AML cells, we first determined our ability to nucleofect primary cells by examining delivery efficiency of fluorescein labeled siRNA. Four different patient samples were evaluated and the mean ± SD of cells successfully transfected was 52%±12. Transfection of multiple AML patient samples with STAT3 siRNA decreased STAT3 expression but led to only modest decrease (6–18% at 48 hour, 7–36% at 72 hour) in AML cell survival. However, transfection of cells with STAT5 siRNA, but not control siRNA, led to a consistent decrease (25–54% at 48 hour, 21–60% at 72 hour) in AML cell survival. The decrease in survival was proportional to the transfection efficiency in the different samples. These results provide the first evidence that STAT5 expression and activation is necessary for the survival of primary AML cells. In fact, the data suggests a greater role of STAT5 in survival of primary cells than in survival of AML cell lines. Accordingly, STAT5 appears to be a legitimate target for the treatment of AML.

scholarly journals A proteomic approach to understand the clinical significance of acute myeloid leukemia-derived extracellular vesicles reflecting essential characteristics of leukemia

2020 ◽  
pp. mcp.RA120.002169
Author(s):  
Ka-Won Kang ◽  
Hyoseon Kim ◽  
Woojune Hur ◽  
Jik-han Jung ◽  
Su Jin Jeong ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Extracellular Vesicle ◽  
The Cancer Genome Atlas ◽  
Enzyme Linked Immunosorbent Assay ◽  
Expression Levels ◽  
Proteomic Approach ◽  
Cancer Genome Atlas ◽  
Acute Myeloid

Extracellular vesicle (EV) proteins from acute myeloid leukemia (AML) cell lines were analyzed using mass spectrometry. The analyses identified 2450 proteins, including 461 differentially expressed proteins (290 upregulated and 171 downregulated). CD53 and CD47 were upregulated and were selected as candidate biomarkers. The association between survival of patients with AML and the expression levels of CD53 and CD47 at diagnosis was analyzed using mRNA expression data from The Cancer Genome Atlas database. Patients with higher expression levels showed significantly inferior survival than those with lower expression levels. Enzyme-linked immunosorbent assay results of the expression levels of CD53 and CD47 from EVs in the bone marrow of patients with AML at diagnosis and at the time of complete remission with induction chemotherapy revealed that patients with downregulated CD53 and CD47 expression appeared to relapse less frequently. Network model analysis of EV proteins revealed several upregulated kinases, including LYN, CSNK2A1, SYK, CSK, and PTK2B. The potential cytotoxicity of several clinically applicable drugs that inhibit these kinases was tested in AML cell lines. The drugs lowered the viability of AML cells. The collective data suggest that AML-derived EVs could reflect essential leukemia biology.

RNAi-Based Functional Genomics Screening of the Human Kinome Identifies Major Growth Regulating Kinases in Acute Myeloid Leukemia Cells

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2951-2951
Author(s):  
Raoul Tibes ◽  
Ashish Choudhary ◽  
Amanda Henrichs ◽  
Sadia Guled ◽  
Irma Monzon ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Acute Myeloid Leukemia ◽  
Gene Silencing ◽  
Functional Genomics ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Large Scale ◽  
Cell Cycle Checkpoint ◽  
Acute Myeloid

Abstract In order to improve treatment strategies for Acute Myeloid Leukemia (AML), we adapted a functional genomics approach using RNAi screening to identify molecular targets that are vital to the growth of AML. Herein we report the first large-scale kinome gene silencing screen in AML. A high throughput RNAi screen was developed for the efficient siRNA transfection of AML cell lines. Eight commercially available cationic lipid-based transfection reagents were tested for their ability to transfect several AML cell lines with siRNA. These extensive transfection optimization experiments identified two AML cells lines TF-1 and ML4 with up to 95–100 and 70–75% transfection efficiency respectively. Two independent replicate kinome screens were performed on both cell lines using a siRNA library targeting 572 kinase genes with 2 siRNA/gene. At 96 hours post transfection, cell proliferation was assessed and the B-score method was used to background correct and analyze the screening data. Several siRNA to specific kinases were identified that significantly inhibit cell proliferation of up to ~40–88%. Hits were defined at two thresholds: siRNA having a B-score of <−2 providing a statistically significance of p<0.05 (confidence of > 95%) and a cutoff B-score of <−1.5 providing greater than 87% confidence for each siRNA hit. Two different kinases (2 siRNA/gene/screen) were identified as major growth regulating kinases in TF1 cells with all 4 siRNA/gene having a B-score <−2. For two additional kinases, 3/4 siRNA for each gene had a Bscore <−2. Expanding the cutoff to a B-score <−1.5 three further kinases were targeted by at least 3/4 siRNA/gene. Similar analysis using the same criteria for ML4 cells identified one kinase targeted by 3/4 siRNA at a B-score <−2, seven kinases with 2/4 siRNA <−2 and two kinases with 3/4 siRNA/gene at a B-score of <−1.5. Common hits for both cell lines with at least 6/8 siRNA per gene from 4 screens performing at a B-score <−2 identified two kinases, one of them PLK1. Applying a B-score threshold of <−1.5, we identified five kinases for which at least 5/8 siRNA/gene from 4 screens met these criteria. Kinases/genes will be presented at the meeting.Confirmation of gene silencing and validation of growth response is currently underway for a subset of genes. Among the strongest hits are siRNA targeting PLK1, as well as siRNA targeting three other kinase-genes involved in regulating cell cycle progression and checkpoints and gene ontology (GO) analysis showed enrichment in cell cycle and cell cycle-checkpoint processes. Inhibitors against PLK1 and other kinase hits identified in the screen are in (pre)-clinical development and if confirmed, our experiments provide a strong rational to test these in AML. The application of RNAi based screening is useful in the identification of genes important in AML proliferation, which could serve as targets for therapeutic intervention and guide AML drug development. Furthermore, results from these types of functional genomics approaches hold promise to be rapidly translated into clinical application.

Incidence and Clinical Impact of TET2 Mutations in Acute Myeloid Leukemia Patients Treated within the EORTC/GIMEMA AML-12/06991 AML Trial.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2609-2609
Author(s):  
M. G Aslanyan ◽  
S. M.C. Langemeijer ◽  
D. Cilloni ◽  
G. Saglio ◽  
JP Marie ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Clinical Outcome ◽  
Myeloid Leukemia ◽  
Regulation Of Gene Expression ◽  
Premature Stop Codon ◽  
Clinical Impact ◽  
Mrna Levels ◽  
Expression Levels ◽  
Therapeutic Decisions ◽  
Acute Myeloid

Abstract Abstract 2609 Poster Board II-585 Defining specific subgroups within AML based on cytogenetic and molecular markers is crucial for diagnostic and prognostic purposes, as well as for adequate therapeutic decisions. Recently, we and others have reported mutations in a novel gene, TET2, that occur in a broad spectrum of myeloid neoplasms. Recent publications regarding the function of the TET protein family members implicate that these proteins play a role in epigenetic regulation of gene expression through DNA methylation, a process known to be disturbed in several hematological malignancies. Thus far, TET2 represents the most frequently mutated gene in myelodysplastic syndromes (26%), and mutations are also frequent in myeloproliferative disorders (12%), mastocytosis (30%), acute myeloid leukemia (10%) and chronic myelomonocytic leukemia (22%). The aim of this study was to define the incidence and clinical impact of TET2 mutations in acute myeloid leukemia patients who were treated uniformously within a defined clinical trial. In addition, we measured the mRNA levels of TET2 in patients with and without TET2 mutations, in order to establish whether the TET2 expression levels might correlate with clinical outcome. We performed direct DNA and/or RNA sequencing of the TET2 gene for mutation analysis and Q-PCR to measure mRNA expression levels. A cohort of up to 400 AML patients that was treated within the EORTC/GIMEMA AML-12/06991 trial was screened. In this trial newly diagnosed patients with AML between 15 and 60 years of age were included, with the exception of patients with acute promyelocytic leukemia. TET2 mutations were detected in 9% of the cases. Mutations were scattered along the whole coding region of the TET2 gene. In 12% of the cases, this led to a premature stop codon, in 24% to a frameshift and premature truncation of the reading frame, and in 60% to missense substitutions, clustering within the two conserved box 1 and box 2 regions of the TET2 gene. In one patient, a splice site mutation was found. TET2 mutations often co-occurred with other well-known mutations, including mutations in the nucleophosmin gene (NPM1), mutations of the fms-like tyrosine kinase 3 (FLT3), and the mixed lineage leukemia gene (MLL). Truncations in the TET2 gene co-occurred most frequently with mutations of NPM1 and FLT3. To determine the clinical significance of TET2 mutations, overall survival of TET2 mutated versus TET2 wild type patients was assessed. Analysis based on the first 224 AML patients showed a clear trend towards poor prognosis of patients carrying a TET2 mutation (p=0.065). So far, TET2 expression levels do not seem to correlate with clinical outcome. The multivariate analysis of the whole cohort will be presented. We conclude that TET2 represents a novel genetic marker that is mutated in approximately 10% of the cases of de novo AML and that in this patient category, mutation of TET2 correlates with poor clinical outcome. Disclosures: Muus: Alexion Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Frequent Epigenetic Inactivation of MSX2 In Acute Myeloid Leukemia

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4645-4645 ◽  
Author(s):  
Chen Zhao ◽  
Xin Han ◽  
Yu H. Zhang ◽  
Xiaoyan Huang ◽  
Aili Dai ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Functional Role ◽  
Methylation Status ◽  
Dna Hypermethylation ◽  
Expression Levels ◽  
Mrna Expression Levels ◽  
Acute Myeloid

Abstract Abstract 4645 DNA hypermethylation has been implicated in the tumorigenesis and prognosis in acute myeloid leukemia (AML). To identify and validate relevant methylated genes in AML, we have compared expression levels and methylation status of 26 candidate genes. One of the interesting candidates identified in our study is MSX2. MSX2 is a member of muscle segment homeobox gene family. MSX2 plays a role in promoting cell growth under certain conditions and may be an important target for RAS signaling pathways. However, the mechanism of transcriptional regulation and functional role of MSX2 in hematological malignancies, especially AML, are poorly understood. In our study, we determined the methylation status, and analyzed the expression levels of MSX2 in AML cell lines and primary AML cells using RT-PCR and/or Taqman real-time PCR. MSX2 mRNA expression was robust in the normal granulocytes and blasts of human bone-marrow, but was either absent or significantly diminished in 6 of 9 (66.7%) AML cell lines. The expression levels of MSX2 in those 6 AML cell lines were restored after treatment of 5-aza 2′-deoxycytidine. In addition, COBRA (Combined Bisulfite Restriction) analysis demonstrated hypermethylation of MSX2 in those AML cell lines (6 of 9, 66.7%), and partial methylation in 3 of 9 AML cell lines. The methylation status was inversely correlated with the mRNA expression levels of MSX2 in those cell lines. Furthermore, the expression levels and methylation status of MSX2 in human primary AML cells were evaluated. COBRA analysis demonstrated frequent hypermethylation of MSX2 in primary AML patient samples (19 of 32, 59.3%). Importantly, the mRNA expression levels of MSX2 as shown by Taqman real-time PCR in those 19 primary AML patient samples were inversely correlated with the methylation status of MSX2. These findings confirmed the role of frequent DNA hypermethylation in silencing MSX2 in AML. We are in the process of determining the functional role of MSX2 in the pathogenesis of AML. In addition, diagnostic and prognostic values of MSX2 in AML are being pursued. Disclosures: No relevant conflicts of interest to declare.

Expression Profiling Of Selected Polycomb Complex Genes In Childhood Acute Myeloid Leukemia Revealed An Overexpression Of EZH2 In Acute Promyelocytic Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4895-4895
Author(s):  
Amanda Faria Figueiredo ◽  
Renata Binato ◽  
Andre Mencalha ◽  
Roberto Capela Matos ◽  
Raul C Ribeiro ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Platelet Count ◽  
Children And Adolescents ◽  
Acute Promyelocytic Leukemia ◽  
Myeloid Leukemia ◽  
Promyelocytic Leukemia ◽  
Mrna Levels ◽  
Expression Levels ◽  
Ezh2 Expression ◽  
Acute Myeloid

Abstract Acute promyelocytic leukemia (APL) in children and adolescents accounts for about 20% of cases of acute myeloid leukemia (AML) in Brazil. The reasons for the relatively high incidence of APL among children and adolescents in Brazil and other Latin countries remain elusive. Epigenetic constitutional and/or environmental factors might be implicated in the mechanism of APL. The Polycomb group (PcG) genes are critical for differentiation and cell-cycle regulation and maintenance of epigenetic memory of living organisms. Aberrant expression of PcG genes has been observed in human tumors, including AML. In this study, we sought to determine the expression levels of 4 genes from the PcG repressive complexes EZH2, YY1, BMI1 and SUZ12 in acohort of 52 children with AML or APL (male, 32; female, 20; median age 7.8 years, range 4 months-18 years). Cells from healthy children (male, 2; female, 2; median age, 10.7 years, range 6-15 years) were used as the control group. Quantitative determination of mRNA levels was performed using Power SYBR Green PCR Master Mix® (Applied Biosystems, Foster City, CA, USA) in a Rotor Gene® thermocycler (QIAGEN). Expression levels were estimated in triplicate, and ß-actin was used as an internal control. All statistical analyses were performed using the GraphPad Prim 5.0 System. Multiple pairwise comparisons were made using a one-way analysis of variance (ANOVA) test; P<0.05 was considered statistically significant. Despite showing broad variation among patients and controls, the expression levels of YY1 (controls, 1.16 ±SE 0.73; M1/M2, 0.63±1.07; M4/M5 0.217±0.71; APL, 0.62±3.24; p=0.19); SUZ12 (control, 1.11 ±0.93; M1/M2, 0.12±1.65; APL 2.4±3.42; M4/M5, 0.34 ± 10.30; p=0.18), and BMI1 (control, 0.041 ± 0.77; M1/M2: 0.043 ±0.10; M4/M5, 0.016± 0.23; APL, 0.12 ± 0.59; p=0.37)did not differsignificantly between controls and patients grouped according to the major AML subtypes (M1/M2, 15 cases, median age 10.8 years, range 4-18 years; M4/M5, 21 cases,median 4.5 years, range 5 months-18 years; APL 16 cases, median 9.8 years, range, 1-17 years). However, the EZH2 expression levels (control, 0.0008818±0.03675; M1/M2, 0.001495±0.03296; M4/M5 0.008215±0.09313; APL, 0.07180± 0.3402; p=0.0092) were significantly higher in APL. Among patients with APL, the expression levels of EZH2 did not differ significantly according to age (EZH2 expression, 0.23±0.44, age 0-8 years; 0.05±0.46, age 9-18 years; p=0.112), white blood cell count (EZH2 expression 0.07±0.65, WBC < 10 x 109/L; 0.10±0.38, WBC ≥ 10 x 109/L; p=0.148) or platelet count (EZH2 expression 0.20±0.49, platelet count < 40 x109/L; 0.06 ±0.04, platelet count ≥ 40 x 109/L; p=0.13). Several studies have shown that EZH2 is deregulated in several human cancers. Here we extend this data by informing that EZH2 is highly overexpressed in pediatric APL. APL in children less than 8 years of age tends to be associated with higher EZH2 gene expression levels, suggesting that constitutional epigenetic factors may play a driver role in pediatric APL leukemogenesis. Disclosures: No relevant conflicts of interest to declare.

The BTK Inhibitor Ibrutinib Blocks SDF1/CXCR4 Mediated Migration of Acute Myeloid Leukemia Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 915-915
Author(s):  
Stuart A Rushworth ◽  
Lyubov Zaitseva ◽  
Megan Y Murray ◽  
Matthew J Lawes ◽  
David J MacEwan ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Lymphocytic Leukemia ◽  
Cell Trafficking ◽  
Acute Myeloid

Abstract Introduction Despite recent significant progress in the understanding of the biology of acute myeloid leukemia (AML) the clinical outcomes for the majority of patients diagnosed with AML presently remain poor. Consequently, there is an urgent need to identify pharmacological strategies in AML, which are not only effective but can be tolerated by the older, less well patient. Recently our group and others have shown that there is high Bruton’s Tyrosine Kinase (BTK) phosphorylation and RNA expression in AML. Moreover, our recent study described for the first time that ibrutinib and BTK-targeted RNA interference reduced factor-induced proliferation of both AML cell lines and primary AML blasts, as well as reducing AML blast adhesion to bone marrow stromal cells. Inhibition of BTK has been shown to regulate chronic lymphocytic leukemia, mantle cell lymphoma and multiple myeloma cell migration by inhibiting SDF1 (stromal derived factor 1) induced CXCR4 regulated cell trafficking. Here we report that in human AML ibrutinib in addition functions in a similar way to inhibit SDF1/CXCR4-mediated AML migration at concentrations achievable in vivo. Methods To investigate the role of BTK in regulating AML migration we used both pharmacological inhibitor ibrutinib and genetic knockdown using a lentivirus mediated BTK targeted miRNA in primary AML blasts and AML cell lines. We examined migration of AML blasts and AML cells to SDF-1 using Transwell permeable plates with 8.0µM pores. Western blotting was used to examine the role of SDF-1 in regulating BTK, AKT and MAPK activation in primary AML blasts. Results We initially examined the expression of CXCR4 in human AML cell lines and found that 4/4 cell lines were positive for CXCR4 expression. Next we examined the effects of ibrutinib on the migration of the AML cell lines U937, MV4-11, HL60 and THP-1 in response to SDF1. We found that ibrutinib can inhibit the migration of all AML cell lines tested. We tested the in-vitro activity of ibrutinib on SDF-1 induced migration in a spectrum of primary AML blasts from a wide age spectrum of adult patients and across a range of WHO AML subclasses and found that ibrutinib significantly inhibits primary AML blast migration (n=12). Next we found that ibrutinib can inhibit SDF-1 induced BTK phosphorylation and downstream MAPK and AKT signalling in primary AML blast. Finally to eliminate the problems associated with off target ibrutinib activity we evaluated migration of AML cells lines using genetic inhibition of BTK. The introduction of BTK-specific miRNA dramatically inhibited the expression of BTK in THP-1 and HL60 and reduced SDF1 mediated migration confirming that BTK is involved in regulating AML migration in response to SDF1. Conclusions These results reported here provide a molecular mechanistic rationale for clinically evaluating BTK inhibition in AML patients and suggests that in some AML patients the blasts count may initially rise in response to ibrutinib therapy, analgous to similar clinical observations in CLL. Disclosures No relevant conflicts of interest to declare.

scholarly journals Critical Role of Lama4 for Hematopoiesis Regeneration and Acute Myeloid Leukemia Progression

Blood ◽  
2021 ◽  
Author(s):  
Huan Cai ◽  
Makoto Kondo ◽  
Lakshmi Sandhow ◽  
Pingnan Xiao ◽  
Anne-Sofie Johansson ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Proliferation ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Critical Role ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Bm Niche ◽  
Acute Myeloid

Impairement of normal hmatopoiesis and leukemia progression are two well-linked processes during leukemia development and controlled by the bone marrow (BM) niche. Extracellular matrix proteins including laminin are important BM niche components. However, their role in hematopoiesis regeneration and leukemia is unknown. Laminin α4 (Lama4), a major receptor-binding chain of several laminins, is altered in BM niches in mice with acute myeloid leukemia (AML). So far, the impact of Lama4 on leukemia progression remains unknown. We here report that Lama4 deletion in mice resulted in impaired hematopoiesis regeneration following irradiation-induced stress, which is accompanied with altered BM niche composition and inflammation. Importantly, in a transplantation-induced MLL-AF9 AML mouse model, we demonstrate accelerated AML progression and relapse in Lama4-/-mice. Upon AML exposure, Lama4-/- mesenchymal stem cells (MSCs) exhibited dramatic molecular alterations including upregulation of inflammatory cytokines that favor AML growth. Lama4-/- MSCs displayed increased anti-oxidant activities and promoted AML stem cell proliferation and chemoresistance to cytarabine, which was accompanied by increased mitochondrial transfer from the MSCs to AML cells and reduced reactive oxygen species in AML cells in vitro. Similarly, we detected lower levels of reactive oxygen species in AML cells from Lama4-/- mice post-cytarabine treatment. Notably, LAMA4 inhibition or knockdown in human MSCs promoted human AML cell proliferation and chemoprotection. Together, our study for the first time demonstrates a critical role of Lama4 in impeding AML progression and chemoresistance. Targeting Lama4 signaling pathways may offer potential new therapeutic options for AML.

scholarly journals ABCB1 Expression in Acute Myeloid Leukemia (AML): A Possible Predictive Value for Treatment Resistance?

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3618-3618
Author(s):  
Stephany Corrêa ◽  
Eliana Abdelhay ◽  
Peter Paschka ◽  
Verena I. Gaidzik ◽  
Rocio Hassan ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Induction Therapy ◽  
Myeloid Leukemia ◽  
Induction Treatment ◽  
Mrna Levels ◽  
Complex Karyotype ◽  
Hematopoietic Stem ◽  
Expression Levels ◽  
The Impact ◽  
Acute Myeloid

Abstract Introduction: Over the last years, there has been a tremendous increase in understanding acute myeloid leukemia (AML) biology and a great effort has been taken in order to improve AML chemotherapy strategies. However, the growing knowledge of leukemia associated molecular mechanisms just started to translate into improved outcome. With regard to conventional chemotherapy multidrug resistance (MDR) is a persisting problem and the impact of ABCB1 (MDR1) expression is still controversially discussed. Methods: In this study we evaluated the ABCB1 expression using qRT-PCR and gene expression profiling (Affymetrix U133plus2.0 arrays) in 250 diagnostic AML samples derived from patients enrolled on a prospective treatment trial of the German-Austrian AML Study Group (AMLSG 07-04 trial; NCT00151242), in which patients were treated with an intensive anthracycline/cytarabine-based induction therapy. Findings were also evaluated in 154 TCGA AML cases receiving a 7+3 induction treatment (data available at http://cancergenome.nih.gov/) and put into perspective with previous reports. Furthermore, we investigated ABCB1 expression associated gene signatures and examined epigenetic regulation mechanisms by COBRA and methyl-CpG immunoprecipitation sequencing (MCIp-seq) in selected cases. Results: Our global analysis showed that patients who obtained a complete response (CR) following double induction therapy had lower ABCB1 mRNA levels compared to patients with refractory disease (RD) (p=0.07). Regarding cytogenetic AML subtypes, ABCB1 mRNA levels varied among the different cytogenetic groups with the complex karyotype group showing the highest ABCB1 and the inv(16) group the lowest ABCB1 expression levels. A comparison of CR versus RD cases within the cytogenetically determined prognostic groups showed that in the intermediate [CN-AML, t(11q23), and other intermediate risk cytogenetic aberrations (othersinter)] and poor risk groups (complex karyotype and othershigh), RD patients presented with significantly higher ABCB1 mRNA levels (p=0.02). Similarly, patients with favorable risk cytogenetics [t(8;21) and inv(16)], who achieved a CR, presented with lower ABCB1 levels compared to the ones, who were refractory. Patients with the lowest ABCB1 expression quartile (ABCB1low) showed significantly longer event-free survival (EFS) times than patients in the highest quartile cohort (ABCB1high) (median EFS 322 vs 105 days; p=0.02), while no differences were observed with regard to overall survival. In accordance, there was a significant enrichment of RD cases in the ABCB1high patient group (p=0.03). Next, in order to better understand the regulation of ABCB1 in AML, we specifically evaluated the DNA methylation level of a previously identified GC box important for ABCB1 expression regulation in CML and we performed global analyses of the entire ABCB1 5' region. While both analyses did not reveal significant differences, further investigation of an ABCB1 associated gene pattern showed a correlation with CD34 and KIT expression (p<0.001). This suggests that like in CML, ABCB1 might be regulated by WNT, and in line, normal CD34+ hematopoietic stem cells also showed high ABCB1 expression levels. Conclusions: In summary, our data provide further evidence for a potential impact of ABCB1 deregulation on the response to AML chemotherapy, especially in more stem cell like leukemia cohorts as well as cytogenetically high risk AML. While we are currently further investigating the involvement of the Wnt/β-catenin pathway in the regulation of ABCB1 transcription in AML, further integration of molecular findings are warranted to better decipher the underlying drug resistance mechanisms. Ultimately, these analyses will improve patient management by adding valuable predictive biomarkers. Disclosures No relevant conflicts of interest to declare.

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