bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monitoring of Hematopoietic Chimerism by Real-Time Quantitative PCR of Single Nucleotide Polymorphisms In Samples with Low DNA Quantities.
Authors: Bach Christian , Tomova Elmira , Goldmann Katja , Lauer Birgit , Roesler Wolf , Mackensen Andreas , Winkler Julia , Spriewald Bernd M 
Published: October 2019

Abstract
Abstract 3491
Novel methods to quantify chimerism after allogeneic hematopoietic stem cell transplantation (HSCT) based on single-nucleotide polymorphism (SNP) specific real-time quantitative polymerase chain reaction (qPCR) require high amounts of input DNA. The applicability of these methods in cases where DNA quantity is limiting, however, is currently unclear. Here, we demonstrate that SNP typing performed with just 5ng of input DNA still allowed for the distinction of positive (mean ct 28.05) and negative (ct > 36) signals. In addition, we confirm the high informative value of a set of 19 SNP markers, with 12 markers exceeding 20% informativity in our population (n=74). Of interest, a four-fold reduction of input DNA for qPCR standard curves did not alter PCR efficiencies. Most importantly, in 7 out of 16 allogeneic HSCT patients who experienced disease relapse, a retrospective analysis using the SNP-qPCR method revealed re-appearance of recipient chimerism earlier (mean 95 days) compared to previous results obtained by a short tandem repeat (STR) specific PCR. Taken together our data clearly demonstrate that SNP-qPCR is more sensitive compared to the widely used STR-PCR even with reduced amounts of input DNA. We therefore recommend that SNP-qPCR is preferable to STR-PCR for chimerism analysis in cases where DNA quantity is a limiting factor.

Disclosures:
No relevant conflicts of interest to declare.
Allogeneic Transplant In Children with Severe Aplastic Anemia – Excellent Outcomes with the Use of a Fludarabine Based Conditioning Regimen
Authors: George Biju , Mathews Vikram , Viswabandhya Auro , Abraham Aby , Kavitha Lakshmi M , Chandy Mammen , Srivastava Alok 
Published: October 2019

Abstract
Abstract 3519
There is limited data on the use of fludarabine based conditioning regimen in children with aplastic anemia though these regimens are increasingly being used in developing countries. Thirty four children (aged < 15 years) including 21 males and 13 females with a median age of 8 years (range: 2–15) underwent allogeneic transplant (HSCT) at our centre between 2004 and 2010 using HLA identical sibling or family donors. The median time from diagnosis to HSCT was 5 months (range: 2–96) and the median number of transfusions prior to HSCT was 10 (range: 3– 64). Five patients (14.7%) had failed treatment with Antithymocyte globulin (ATG) and 4 (11.4%) had an intracranial bleed in the 3 months prior to HSCT. Conditioning regimen consisted of Fludarabine 150 mg/m2 over 5 days and Cyclophosphamide 120 mg/kg over 2 days. Antithymocyte globulin (ATGAM) [10 mg/kg/day for 4 days] was used in 9 patients. Graft source consisted of either bone marrow [9 patients] or G-CSF stimulated peripheral blood stem cells (PBSC)[25 patients]. Graft versus host disease (GVHD) prophylaxis consisted of Cyclosporine and short course methotrexate. The median cell doses infused were 4.9 × 108 TNC/Kg for bone marrow and 8.5 × 108 MNC/Kg for PBSC. Thirty patients (88.2%) engrafted while 2 (5.8%) had primary graft failure. Two children died on Day 0 and Day +5 respectively due to infection. The median time to neutrophil engraftment was 14 days (range: 8–19) while the median time to platelet engraftment was 12 days (range: 7–24). Two patients (5.8%) developed veno-occlusive disease (VOD) of the liver while none developed hemorrhagic cystitis. Acute graft versus host disease (GVHD) was seen in 7 patients (23.3%) and was grade 1–2 in all patients. Chronic GVHD was seen in 31% of patients who could be evaluated and was limited in nature in a majority of patients. Of the 2 patients with primary graft failure, one was rescued with a second transplant while the second expired due to fungal pneumonia. The Day 100 mortality was 14.1%. Secondary graft failure was seen in 1 patient but was rescued with a second transplant using the same donor. At a median follow up of 30 months (range: 1 –67), 29 patients are alive for a 3 year OS of 85.1%. Fludarabine based conditioning regimens are associated with favorable outcomes in Indian children with aplastic anemia. These results are superior to an OS of 37% with the use of ATG and Cyclosporine in a similar population (George B et al PHO March 2010).

Disclosures:
No relevant conflicts of interest to declare.
Cysteinyl Leukotrienes Signal Via Overexpressed CysLT1, but Not CysLT2 Receptor In Chronic Lymphocytic Leukemia
Authors: Drost Adriana , Funk Mirjam , Norz Karoline , Zipfel Anne , Kanz Lothar , Mohle Robert 
Published: October 2019

Abstract
Abstract 3612
The G Protein-coupled receptors (GPCRs) CysLT1 and CysLT2 are both expressed in peripheral blood mononuclear cells (PBMNC). Their ligands are inflammatory mediators of the cysteinyl leukotriene (cysLT) family and contribute, together with ligands of other GPCRs such as chemokines, to migration and proliferation of a variety of cell types. In the present study, we demonstrate by real-time RT-PCR that CysLT1 mRNA is overexpressed in B-CLL cells compared to both normal PBMNC and normal CD19+ B cells, whereas only low levels of CysLT2 mRNA are present. GPCR-typical cellular responses such as intracellular calcium fluxes and actin polymerization, which were induced by the cysLT LTD4 in CLL cells in a dose-dependent manner, were suppressed by the CysLT1 antagonist MK571, the prototype of the lukast family of drugs used in asthma treatment (e.g., montelukast). However, MK571 and other lukasts also block the leukotriene transporter MRP. The fact that the CysLT1 antagonist LY171883, which has no effect on MRP, also abrogated the responses of CLL cells indicates that the effects of cysLTs are mediated solely by CysLT1. Moreover, also chemotaxis was induced by the cysLT LTD4 in B-CLL cells (optimum at low nanomolar concentrations) and could be blocked by MK571. We further observed inhibiting effects of MK571 on cysLT-induced Erk/MAP kinase phosphorylation in B-CLL cells, which suggests an involvement of CysLT1 in cell proliferation. Indeed, MK571 significantly induced apoptosis of CLL cells in vitro and reduced survival of cultured B-CLL cells. However, the concentrations for a significant reduction of cell viability were higher (1-10 μM) than the concentration required for efficient CysLT1 receptor inhibition (0.1 μM). Thus, the influence of MK571 on B-CLL cell survival may mainly be due to direct effects on apoptosis occuring at the higher dose level and/or blocking of the leukotriene transporter MRP. Accordingly, LY171883 and the combined CysLT1/2 antagonist Bay-u9773 did not induce CLL apoptosis. Our results suggest that CysLT1 is overexpressed in B-CLL cells and involved in cell trafficking, similar to the chemokine receptor CXCR4. Considering the redundancy among GPCRs and the limited effect of MK571 on cell survival, CysLT1 for its own represents a less attractive therapeutic target using the currently available CysLT1 antagonists of the lukast family. However, combined inhibition of several GPCRs highly expressed in CLL cells including cysLT1 and CXCR4 may constitute a promising therapeutic approach and should be further evaluated.

Disclosures:
No relevant conflicts of interest to declare.
B-Cell Lymphoma Cells Overexpressing BMI-1 Are Correlated with Drug Resistance through Enhanced Expression of Survivin and Are Effectively Eliminated by T Cells with Anti-CD38 Chimeric Receptor
Authors: Bhattacharyya Joyeeta , Mihara Keichiro , Ohtsubo Motoaki , Yasunaga Shin'ichiro , Takihara Yoshihiro , Hoshi Masaharu , Kimura Akiro 
Published: October 2019

Abstract
Abstract 3613
BMI-1 is essential for the self-renewal and proliferation of leukemic and hematopoietic stem and progenitor cells. Increased expression of BMI-1 is known to be an indicator for a poor prognosis in cancer patients. Analysis of the expression of BMI-1 and survivin in 6 patients with B-cell lymphoma (3 drug-resistant and 3 sensitive cases) showed that in the drug-resistant patients, high levels of BMI-1 and survivin were maintained even after drug administration in vitro. However, there observed was a down-regulation of both BMI-1 and survivin expression in the drug-sensitive patients. BMI-1 transduction induced the drug-resistance of two B-cell lymphoma cell lines, HT and RL, to the anti-cancer drugs etoposide and oxaliplatin, but not to irinotecan. The expression of survivin was clearly augmented in the cells transduced with BMI-1. Moreover, we detected sustained expression of survivin level in the presence of etoposide in the BMI-1-overexpressing cells. By contrast, the mock-transduced cells succumbed in the medium with anti-cancer drugs with an accompanying decrease in the expression of survivin as well as BMI-1. Survivin has been reportedly implicated in resistance to chemotherapeutic agents. Intriguingly, survivin mRNA levels in BMI-1-overexpressing cells were consistent with those in controls. Also, the level of survivin was enhanced by treatment with a proteasomal inhibitor, MG132, suggesting that overexpression of BMI-1 stabilized survivin expression post-translationally. We further showed that sh RNA-mediated knockdown of BMI-1 or survivin restored sensitivity to etoposide in the HT cells overexpressing BMI-1. Our findings suggest survivin as a potential target for BMI-1. Thus BMI-1, by acting as an upstream regulator, may control the expression of survivin, facilitating drug resistance in B-cell lymphoma. Next, we examined whether B-cell lymphoma cells overexpressing BMI-1 are abrogated by immunotherapy with T cells containing anti-CD38 chimeric receptor in vitro. Interestingly, these B-cell lymphoma cells were effectively eliminated by specific T cells against B-cell lymphoma cells bearing CD38. These results suggest that the immunotherapy is useful for treatment of patients with B-cell lymphoma cells overexpressing BMI-1, which are refractory to chemotherapeutic reagents. BMI-1 may be an important prognostic marker as well as a future therapeutic target in the treatment of drug-resistant lymphomas.

Disclosures:
No relevant conflicts of interest to declare.
TEL-AML1 Affects the Regulation of Cytoskeleton and Causes Alteration In Cellular Adhesive and Migratory Properties In An In Vitro Model of Pre-Leukemia.
Authors: Palmi Chiara , Fazio Grazia , Brunati Ilaria , Cazzaniga Valeria , André Valentina , Sozzani Silvano , Villa Antonello , Ford Anthony , Greaves Mel , Biondi Andrea , Cazzaniga Giovanni 
Published: October 2019

Abstract
Abstract 3624

Introduction:
The t(12;21) chromosome translocation generating TEL-AML1 chimeric fusion gene is a frequent initiating event in childhood leukaemia. Its impact is to generate a clone of covert, clinically silent pre-leukemic B cell progenitors. The leukemia arises only following second, post-natal hit/genetic events occurring years later. Moreover, relapse of leukemia is frequently arising from the pre-leukemic clone.

Aim
of our study is to investigate how TEL-AML1 expression can sustain this covert condition for many years. In a recent paper we described that the fusion gene rendered the B precursors resistant to the inhibitory activity of TGFbeta. Here we want to inquire into other factors that can explain the positive selection of the pre-leukemic clones over the normal counterpart. In particular, given the importance of the interaction with the microenvironment for survival signals for normal and leukemic stem cells, we question if the fusion gene causes changes in cellular adhesive and migratory properties.

Methods:
the study was performed by using two different models: i) a TEL-AML1 inducible expression system on the murine pro-B Ba/F3 cell line and ii) murine primary B lymphocytes (pre-BI cells) isolated from fetal liver, stably transduced with the pMIGR1-TEL-AML1-IRES-GFP construct. Gene expression assays were performed by using TaqMan (Applied Biosystems) and PCR Array technologies (SABioscences).

Results:
The expression of TEL-AML1 in Ba/F3 cell line causes over-expression of genes regulators of the cytoskeleton, specifically involved in cellular movement and in the regulation of actin dynamics. This gene expression alteration results in changes in the cellular morphology and phenotype: the cells acquire long extensions and several molecules involved in cell adhesion and migration are disregulated. Moreover, the TEL-AML1 positive cells present an increased ability to adhere to the ICAM1 substrate, but they also show a significant defect in the chemotactic response to CXCL12 in transwell migration assays in vitro, although the expression and the recycling of CXCR4 receptor are unaffected. This inability is not due to defects to migrate in general, as spontaneous motility is enhanced, but it is associated with a defect in CXCR4 signaling. In particular, CXCL12 calcium flux and ERK phosphorylation were inhibited. Those results have been confirmed in murine PreBI primary cells.

Conclusions:
in our murine models, TEL-AML1 affects the cytoscheleton regulation and causes alteration in cellular adhesive and migratory properties. We are now investigating how these alterations can give advantages to the pre-leukemic cells in the pathogenesis of TEL-AML1–expressing leukemia.

Disclosures:
No relevant conflicts of interest to declare.
Epigenetic Silencing of a Novel Candidate Tumor Suppressor “miR” Predicts Poor Prognosis In High-Risk MDS and AML.
Authors: Treppendahl Marianne B. , Qiu Xiangning , Hother Christoffer , Andersen Mette K. , Kjeldsen Lars , Jones Peter , Liang Gangning , Gr∅nbæk Kirsten 
Published: October 2019

Abstract
Abstract 3629

Introduction:
A tumor suppressor has long been sought for in the commonly deleted region on chromosome 5q in myelodysplastic syndrome and acute myeloid leukaemia (MDS/AML). MicroRNAs (miRs) may have tumor suppressor function since they may repress the expression of proto-oncogenes through post-transcriptional regulation by binding to the 3′UTR of mRNA. It has recently been shown that several types of haematological malignancies have globally altered expression of miRs. DNA methylation cause targeted down regulation of individual tumor suppressor genes that may be directly involved in the pathogenesis of MDS/AML and we speculated whether epigenetic downregulation of miRs also plays a role in MDS/AML pathogenesis.

Methods:
Cell lines were treated with the hypomethylating agent 5-azacytidine. Upregulated miRs were identified by microarray (Exiqon) analysis and confirmed by RT qPCR analysis. Transcription start site was determined by 5′RACE and promoter methylation by methylation specific melting curve analysis. MiR expression and processing were analysed by qPCR, Northern blotting, and si-RNA mediated knock down of Drosha. Clinical data were collected from patient files.

Results:
We focused on one upregulated miR that locates to the commonly deleted region of AML/MDS. We found that the processing of this “miR” was independent of Drosha, and northern blotting showed that this was in fact a different type of non-coding RNA (ncRNA). The gene that encodes this ncRNA has a CpG island at the transcription start site. This CpG island is unmethylated in normal CD34+ cells, normal peripheral blood lymphocytes and methylated in three different myeloid cells lines (HL60, NB4, F-36P). Normal CD34+ cells and normal peripheral blood lymphocytes expressed the ncRNA, while no expression was seen in the cell lines. However, treatment by 5-azacytidine derepressed expression of this ncRNA. Bone marrow mononuclear cells from 101 high-risk MDS and AML patients, isolated at the time of diagnosis, were examined for methylation of the ncRNA promoter. Methylation was detected in 48% of the patients. Patients with no methylation have a significant better survival as compared to patients with methylation of the promotor.

Discussion:
This is the first example of targeted methylation of this type of RNA that has not previously been implicated in cancer. The preliminary results indicate that methylation of this ncRNA may be used as a prognostic marker for survival in high-risk MDS- and AML patients. We are currently investigating the function of this ncRNA by performing stable transfections into MDS/AML cell lines.

Disclosures:
Jones: Lilly: Consultancy; Millipore: Consultancy.
Downregulation of Protein Arginine Methyltransferase – 4 (PRMT4) Promotes MiR-223 Expression and Myeloid Differentiation.
Authors: Vu Ly P , Zhao Xinyang , Perna Fabiana , Nimer Stephen D 
Published: October 2019

Abstract
Abstract 3632
Protein arginine methyltransferase 4 is a Type I member of PRMT family, that catalyses the addition of a methyl-group to arginine residues of a wide range of proteins, including histones, transcription factors, and RNA binding proteins. PRMT4 has been shown to regulate gene expression through its interaction with various transcription factors and via methylation of numerous substrates. Although PRMT4 has been reported to play an important role in T cell development, lung development and adipocyte differentiation in mouse models, the function of PRMT4 during hematopoiesis has not been studied.
To investigate the function of PRMT4 in the hematopoietic system, we utilized human CD34+ haematopoietic stem/progenitor cells (HSPCs). We observed that PRMT4 protein level is markedly downregulated during the myeloid differentiation of CD34+ cells without a significant change in the mRNA level. We then utilized a loss of function approach, using short hairpin RNAs, and found that knockdown of PRMT4 leads to an acceleration of myeloid differentiation, with a concomitant loss of the clonogenic potential of the cells. Interestingly, knocking down PRMT4 results in upregulation of miR-223, a myeloid specific microRNA. We also found that, during the myeloid differentiation of CD34+ cells, miR-223 expression steadily increased. Using a microRNA target prediction program, we identified a binding site for miR-223 in the 3′-UTR region of PRMT4 and found that when we over-expressed miR-223 in CD34+ cells, PRMT4 protein expression decreased. To determine the importance of PRMT4 downregulation in myeloid differentiation, we expressed the PRMT4-ORF (that should not be regulated by microRNAs) in CD34+ cells. The forced expression of PRMT4, that lacks the 3′-UTR region, leads to a block in myeloid differentiation and the inability of cells to up-regulate miR-223 during differentiation. Taken together, these data indicate a regulatory loop between PRMT4 and miR-223 that controls the differentiation of CD34+ toward the myeloid lineage.
To examine how PRMT4 regulates transcription of miR-223, we examined the miR-223 locus and found a RUNX1 binding site in the promoter of pri-miR-223. We discovered that PRMT4 interacts with RUNX1 and methylates RUNX1 at a specific arginine residue. This results in the recruitment of several novel interacting partners, which appear to control the expression of miR-223. Thus our results indicate that PRMT4 regulate the transcription of miR-223 transcription via its effects on RUNX1. Our study demonstrates a novel function of PRMT4 in myeloid differentiation, through regulation of RUNX1 function and miR-223 expression.

Disclosures:
No relevant conflicts of interest to declare.
Genetic and Epigenetic Silencing of Mesoderm Specific Transcript (MEST) In Acute Myelogenous Leukemia.
Authors: Poetsch Anna R , Claus Rainer , Bullinger Lars , Witte Tania , LÃ¼bbert Michael , Rehli Michael , Döhner Konstanze , Plass Christoph 
Published: October 2019

Abstract
Abstract 3639
About 10 % of patients with either myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) present either with deletions on the long arm of chromosome 7 or monosomy 7. These chromosomal aberrations are associated with a poor prognosis. Following biallelic inactivation as proposed by Knudsen, a “second hit” of the remaining allele might be required for loss of gene function. Epigenetic silencing might display such a hit in particular since no additional genetic hits could be identified so far. The role of epigenetic regulation might be of special importance in patients with -7/7q-, since several studies have shown that patients harbouring a chromosome 7 abberrations do more benefit from a therapy with demethylating agents as compared to patients with other chromosomal changes.
To address the issue of epigenetic silencing in these AML cases we utilized DNA methylation profiling to identify the potential tumor suppressor genes on chromosome 7.
We used MBD2 based enrichment of methylated DNA from 4 AML patient samples with monosomy 7 and from 23 patient samples with with other chromosomal changes including normal karyotype AML. For validation we analyzed regional DNA methylation using quantitative MassArray technology on DNA from 115 del(7q) AML or monosomy 7 patients as well as normal karyotype patients (n=20) and CD34 + cells from healthy individuals (n=5).
We could identify the gene MEST to be silenced by hypermethylation (> 30 %) of a CpG island on the remaining allele in 20% of the patients with -7/7q- and 40% of patients with normal karyotype. Thus, preferentially in patients that do not have a deletion already.
MEST is an imprinted gene located on 7q32.2. However, silencing is correlated with hypermethylation of a CpG island located at an alternative promoter of MEST, independent of the methylation status of the imprinting control region.
In two patient samples with monosomy 7 and hypermethylation of MEST (> 80%), DNA methylation was erased after 5-Aza-2′-deoxycytidine (DAC) treatment to less than 10 %. In concordance, also AML cell lines with hypermethylation of the MEST locus loose methylation after sublethal DAC treatment which leads to a reexpression of the gene.
Thus, we hypothesize that MEST functions as a tumor suppressor in AML and is genetically as well as epigenetically silenced AML. Reactivation of MEST by demethylating treatment may contribute to the mechanism by which demethylating drugs display their therapeutic potential in leukemia.

Disclosures:
No relevant conflicts of interest to declare.