bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deciphering Molecular Control of VEGFR2 Regulation in Hematopoietic Progenitors: GATA1-Mediated Repression of VEGFR2 Promotes Optimum Erythropoiesis
Authors: Ganguly Avishek , Aljitawi Omar S. , Paul Soumen 
Published: October 2019

Abstract
VEGFR2 (also known as Flk1) is expressed in hemetopoietic precursors and is essential for both hematopoietic and vascular development. Interestingly, development of differentiated hematopoietic cell from hematopoietic stem cells (HSCs) is associated with VEGFR2 repression, whereas VEGFR2 expression is maintained throughout endothelial development. This differential regulation of VEGFR2 has been implicated as a key step to successfully branch out hematopoietic vs. endothelial development. However, molecular mechanisms that regulate transcriptionally active vs. repressive Vegfr2 chromatin domains in hematopoietic stem/progenitor cells (HSPCs) vs. differentiated hematopoietic cells are incompletely understood. Here, we report that transcription factor GATA1, a master-regulator of erythroid differentiation, is essential to repress VEGFR2 expression in erythroid progenitors. Genetic complementation analysis demonstrated that VEGFR2 expression in maintained in GATA1-null erythroid progenitors and rescue of GATA1-function induces VEGFR2 repression. Mechanistic studies in primary hematopoietic progenitors from mouse fetal liver and differentiating mouse embryonic stem cells (ESCs) identified a repressor element at the (-)88 kb region of the Vegfr2 locus from which GATA1 represses Vegfr2 transcription in erythroid progenitors. Furthermore, CRISPR/Cas9-mediated deletion of the Vegfr2(-)88 kb region results in reduced erythroid differentiation during fetal liver hematopoiesis. These results indicate that GATA1-mediated repression of VEGFR2 could be a determinant of optimum erythropoiesis.

Disclosures
No relevant conflicts of interest to declare.
Gadd45a Loss Enhances MLL Leukemogenesis By Promoting Beta-Catenin Mitochondrial Translocation and Inhibiting Apoptosis
Authors: Voli Florida , Yi Hangyu , Martinez Brendon , D'Andrea Richard J , Wang Jenny Yingzi 
Published: October 2019

Abstract
Gadd45a is a mediator of growth arrest and its expression is suppressed in primary human MLL-rearranged AML (predominantly MLL-AF9) and AML1-ETO AML with increased FLT3 expression (Valk et al., N Engl J Med 2004; Perugini et al., Leukemia 2009). While Gadd45a is frequently silenced in several human cancers, including leukemia, little is know about how Gadd45a loss contributes to leukemogenesis. Our studies have shown that Gadd45a loss promotes MLL-AF9 mediated development in AML in mice and protects leukemic cells from apoptosis via novel β-catenin/mitochondria pathway.
To explore the functional role of Gadd45a loss in MLL-rearranged AML, we retrovirally introduced MLL-AF9 into c-Kithigh progenitors isolated from Gadd45a knockout mouse bone marrow cells. Our results showed that Gadd45a knockout markedly reduced the colony forming capacity of pre-leukemic cells and significantly shortened the latency for MLL leukemia development in mice (p = 0.037, N = 6 mice). As Gadd45a could induce cell death through the mitochondria pathway (Tong et al., Mol Cell Biol 2005), we next examined the expression of proteins involved in the mitochondrial apoptosis in Gadd45a knockout pre-leukemic cells. Our western blot analysis showed that Gadd45a knockout dramatically decreased expression of pro-death proteins Txnip, Bim and Bax but interestingly, significantly increased active β-catenin expression in mitochondria. Given that Gadd45a has been reported to regulate β-catenin distribution (Ji et al., Oncogene 2007), we postulate that Gadd45a loss facilitates the translocation of β-catenin into mitochondria. We have previously demonstrated that β-catenin is highly expressed in MLL-AF9 transformed pre-leukemic cells and is lower in Hoxa9/Meis1 transformed pre-leukemic cells, while increased β-catenin expression is correlated with a poor survival rate in mice. Here, we retrovirally introduced a constitutively active form of β-catenin into Hoxa9/Meis1 pre-leukemic cells. As expected, activation of β-catenin reduced endogenous expression of Txnip and Bim in mitochondria, exhibiting an expression pattern similar to that regulated by Gadd45a knockout. Consistently, both Gadd45a knockout and β-catenin activation not only reduced the basal cellular reactive oxygen species (ROS) levels but also inhibited Antimycin A (an ROS generator)-induced mitochondrial ROS production.
Taken together, our study discovers a previously unrecognized Gadd45a loss/β-catenin/mitochondria pathway that prevents mitochondrial ROS accumulation and protects leukemic cells from cell death in MLL leukemogenesis.

Disclosures
No relevant conflicts of interest to declare.
CD8 Tregs Promote Gvhd Prevention and Restore Impaired GVL Effect Mediated By CD4 Tregs in Mice
Authors: Heinrichs Jessica Lauren , Nguyen Hung , Bastian David , Wu Yongxia , Daenthanasanmak Anusara , Yu Xue-Zhong 
Published: October 2019

Abstract
Adoptive regulatory T-cell (Treg) therapy has enhanced the outcome of patients suffering from graft-versus-host (GVH) disease following allogeneic hematopoietic stem cell transplantation (allo-HCT); however, fear of broad immune suppression and subsequent dampening of the beneficial graft-versus-leukemic (GVL) responses remains a challenge. In order to subvert broad immune suppression, we generated alloantigen-specific induced Tregs (iTregs) from resting CD4 or CD8 T cells and tested the ability of iTregs to suppress GVH and maintain GVL responses. We utilized a clinically relevant murine model of haploidentical-HCT with the addition of host-original leukemia cell line to evaluate the effects of CD4 and CD8 iTregs in GVH and GVL responses. While alloantigen-specific CD4 iTregs were effective in preventing GVHD (Fig. 1 A and C), they completely abrogated the GVL effect against aggressive leukemia resulting in 100% tumor mortality (Fig. 1 B and D). Mechanistically, these CD4 iTregs were found to potently suppress the expansion of effector T cells (Teffs) and their ability to secrete IFNγ and granzyme B in the recipient spleen and liver, which may contribute to the impaired GVL activity. Using similar approach, we generated alloantigen-specific CD8 iTregs and found they express higher levels of granzyme B and CTLA-4 compared to nTreg and CD4 iTregs. In vivo studies showed these CD8 iTregs moderately attenuated GVHD (Fig. 1 A and C)while completely sparing the GVL effect (Fig. 1 B and D). We thus further reasoned that the combination of CD4 and CD8 iTregs could achieve the optimal goal of allo-HCT: GVHD suppression with GVL preservation. Indeed, the combination therapy potently suppressed GVHD resulting in increased survival and decreased pathological injury to target organs than either CD4 or CD8 iTreg singular therapy (Fig. 1 A and C). More importantly, the combination therapy maintained potent GVL responses reflected by significantly decreased tumor mortality and load (Fig. 1 B and D).Mechanistically, we observed addition of CD8 iTregs maintained the suppression of Teff expansion but restored the ability of Teffs in producing inflammatory cytokines (e.g. IFNγ and TFNα) and cytolytic effector molecules (e.g. granzyme B and TRAIL). To our knowledge the current findings are the first to support the use of combinational iTreg therapy to achieve optimal suppression of GVHD while maintaining GVL responses.
This work was supported by NIH grants: R01 CA118116 and R01 CA169116

Disclosures
No relevant conflicts of interest to declare.
Lower Use of DLI Post Relapse of Malignancy May Result in Shorter Post-Relapse Survival (PRS) in Patients Undergoing T Cell Replete Haploidentical Donor Transplantation (HIDT) Versus Matched Related (MRD) or Matched Unrelated Donor (MUD) Hematopoietic Cell Transplantation (HCT)
Authors: Solh Melhem , Zhang Xu , Brown Stacey , Morris Lawrence E. , Holland H. Kent , Solomon Scott R. , Bashey Asad 
Published: October 2019

Abstract

Relapse of hematologic malignancies remains a major cause of treatment failure and mortality among patients receiving allogeneic hematopoietic cell transplantation (HCT). Patients relapsing after a matched related or unrelated donor transplantation may benefit from donor lymphocyte infusion (DLI) as part of their post relapse therapy. DLI post-relapse has less frequently been utilized among recipients of HIDT presumably due to the potential for severe GVHD if high T-cell doss are administered without immunosuppression. However, reluctance to administer DLI may limit the possibility of remission following disease relapse in HIDT. We compared the frequency of use of DLI and survival outcomes for patients relapsing after HIDT using post-transplant cyclophosphamide to those relapsing after MRD or MUD HCT at our institution.
195 consecutive HCT recipients with relapse of hematologic malignancy occurring after HIDT (N=35), MUD (N=74) and MRD (N=81) between 1998 and 2014 were included in this analysis. The median age was 50 years (19-77 years) and median time to relapse was 159 days (25-2465 days) post HCT. Patients receiving HIDT had similar median time to relapse (5.1 vs 5.2 vs 5.2 months, p=0.638), Dana-Farber/CIBMTR disease risk index (DRI), comorbidity index (CMI) scores, longer times to neutrophil engraftment (17 vs 14 vs 14 days, p<0.001), and platelet engraftment (28 vs 19 vs 18 days, p<0.001) when compared to MUD and MRD recipients respectively. Post-relapse survival at 1 year was worse among HIDT recipients when compared to MRD (9% versus 41%, p=0.008) and MUD (9% vs 35%, p=0.025). DLI was used in 3 (8%) relapsed HIDT patients, 48 MRD patients (59%) and 28 (38%) MUD recipients. Among patients relapsing post MRD and MUD HCT, use of DLI was associated with a better post relapse survival (p=0.04). In a multivariate analysis, donor type (HIDT), time to relapse (<3 months versus > 3months post-transplant) and comorbidity index (CMI score >= 3) were all predictive of worse post relapse survival.
This analysis shows that relapse post HIDT carries a worse prognosis than relapse post MRD and MUD. Efforts such as post-transplant maintenance and haploidentical DLI infusions should be investigated further in the HIDT setting.
Figure 1. Figure 1. Figure 2. Figure 2.

Disclosures
No relevant conflicts of interest to declare.
NON-Cryopreserved Hematopoietic STEM CELL Transplantation in Multiple Myeloma. a Single Center Experience in Oran (ALGERIA)
Authors: Bekadja Amine MA , Talhi Souad ST , Ouldjeriouat Hafida OH , Soufi Osmani OS , Brahimi Mohamed BM , Bouhass Rachid Amar RB , Yafour Nabil , Arabi Abdessamed AA 
Published: October 2019

Abstract
Introduction:
For younger patients under 65 years of age, induction followed by high-dose chemotherapy with autologous stem cell transplantation (ASCT) is the standard treatment in multiple myeloma (MM). There is limited experience with non-cryopreserved autologous hematopoietic stem cell transplantation. We evaluated the efficacy and safety of non-cryopreserved storage of ASCT in patients undergoing ASCT for MM.
Patients and methods:
Autologous stem cell was mobilized using G-CSF alone (10 µg/kg/day for 5 days). Leukapheresis to harvest stem cells were performed on day -2 and -1. The grafts were kept in a conventional blood bank refrigerator at +4°C until reinfusion on day 0. The conditioning regimen consisted of melphalan 200 mg/m2 in all patients.
Results:
From May 2009 to December 2013, 134 patients with MM were treated in our center in Oran. The median age at ASCT was 55 years (range; 27-67). There were 80 males and 54 females. The median harvested CD34+ cell count was 3,5x106/kg (range; 1, 22 to 13, 24). All patients had engraftment on the median of day 10 (range; 7 to 17) and platelet transfusion independence on the median of day 13 (range; 9 to 24). There was no graft failure. Mucositis grade 3/4 was seen in 68% patients. Transplant related mortality at 100 days was 2.9%. The overall response to transplant was 92%.
In the 130 evaluable patients, the median post-transplant overall survival had not been reached. The estimated overall survival at 75 months was 63% with 95% confidence interval and the median post-transplant disease free Survival was 35 months (0.05%). 93 (72%) patients are alive and 75 (81%) without disease activity after a median follow-up of 35 months (range; 3 to 75).
Discussion:
We conclude that high dose chemotherapy and autologous transplant with non cryopreserved ASCT is a simple, effective and safe method for MM with equivalent results, and that cryopreservation is not necessary in the treatment of MM under our work conditions in developing countries

Disclosures
No relevant conflicts of interest to declare.
Grouping of Genetic Risk By the European Leukemia Net Classification Predicts Overall Survival and Relapse Incidence in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation
Authors: Hemmati Philipp G. , Terwey Theis , Na Il-Kang , Jehn Christian , Vuong Lam G. , le Coutre Philipp , Dörken Bernd , Arnold Renate 
Published: October 2019

Abstract
Introduction: In acute myeloid leukemia (AML) genetic risk factors are among the strongest predictors for overall outcome. Recently, the European Leukemia Net (ELN) proposed a revised classification based on the presence or absence of specific cytogenetic and/or molecular aberrations. Here, we evaluated the prognostic significance of this system in patients with AML undergoing allogeneic stem cell transplantation (alloSCT).
Patients and Methods: A total of 363 patients transplanted at our center between 2004 and 2014 was retrospectively evaluated. According to the ELN classification genetic risk was favorable (N=51), intermediate-1 (N=120), intermediate-2 (N=98), or adverse (N=94). Remission status at the time of alloSCT was first complete remission (CR1) (N=204), CR>1 (N=61), or refractory (N=98). In 107 patients standard myeloablative conditioning (MAC) was used, whereas reduced intensity conditioning (RIC) was applied in 256 patients. Grafts were from either related (N=103) or unrelated (matched: N=191, mismatched: N=69) donors. The median age was 52 (range: 18-75) years.
Results: For the surviving patients the median follow-up was 30 (range: 3-129) months. Whereas in the subgroup of patients aged ≥60 years (N=98) no significant differences in disease-free survival (DFS) or cumulative incidence of relapse (CI-R) between the 4 ELN subgroups were found, the ELN classification was highly predictive for in the subgroups aged <60 years. Patients with an adverse risk karyotype had significantly lower DFS as compared to patients with a favorable or an intermediate risk profile, i.e. 30% versus 56% for favorable, 52% for intermediate-1, or 59% for intermediate-2 (p=0.0064). Correspondingly, the CI-R was highest in patients with an adverse risk profile, i.e. 53% at 5 years. In turn, patients with favorable, intermediate-1, or intermediate-2 risk disease had a CI-R of 15%, 40%, or 21% (p<0.001). In the intermediate-1 subgroup, adverse outcome, i.e. relapse, was predominant in the group of FLT3-ITD positive patients, whereas the CI-R in patients lacking a FLT3-ITD was similar to what was observed in the intermediate-2 subgroup.
Conclusions: Taken together, our data suggest that the ELN classification of genetic risk is suitable for predicting relapse and overall survival of patients with AML aged <60 years undergoing alloSCT. The adverse outcome of patients in the intermediate-2 subgroup may be related to presence of a FLT3-ITD. Therefore, further efforts are needed to improve the clinical results in this particular group.

Disclosures
No relevant conflicts of interest to declare.
Disparities in Receipt of Radiotherapy and Survival By Age, Sex and Ethnicity Among Patients with Stage I Follicular Lymphoma
Authors: Shah Binay K. , Bista Amir , Sharma Sandhya 
Published: October 2019

Abstract
Background: Radiotherapy (RT) is a first line treatment option for stage I follicular lymphoma. In this population-based study, we evaluated disparities in receipt of radiotherapy and survival among patients with stage I follicular lymphoma.
Methods: Adult patients (age ≥18 years) with stage I follicular lymphoma, as the first primary cancer, diagnosed between 1992 and 2007 were identified using Surveillance, Epidemiology and End Results (SEER) 18 database. Study population was divided into various groups based on age (<60 years and ≥60 years), sex, ethnicity (Caucasians, African Americans and Others) and marital status (married, single and separated/divorced/widowed). Binomial logistic regression was used to analyze factors associated with receipt of RT. SEER*Stat was used to compute 5 year RS for various groups and compared using Z score. Cox proportional hazard model was used to compare factors associated with 5 year RS.
Results: Of the total 7328 patients (median age: 63 years), 2675 (36.5%) received RT. African Americans were less likely to receive RT compared to Caucasians (adjusted odds ratio [OR] of 0.602;P <0.001). Older patients (≥60yrs) were less likely to receive RT compared to younger patients (adjusted OR of 0.636; P<0.001). Single and S/D/W were less likely to receive RT compared to married (adjusted OR of 0.835 and 0.865 with P of 0.029 and 0.029 respectively). Recent years of diagnosis was independent predictor of omission of RT (adjusted OR for one year increase is 0.975, P <0.001). 5 years RS was significantly better in patients receiving RT (97%+0.7% vs. 88.4%+0.7%, P <0.0002). In multivariate analysis, male sex, age <60years , Caucasian race and married marital status were found to be independent predictor of better RS among patients receiving RT (P <0.000001).
Conclusion: Among patients with stage I follicular lymphoma, receipt of RT is associated with superior survival. Patients belonging to AA and Others race, old age group, single and S/D/W as marital status and recent years of diagnosis were independent predictors for omission of RT. 5 year RS among the patients receiving RT was significantly better for male, younger age, Caucasians and married patients.

Disclosures
No relevant conflicts of interest to declare.
Non-Hodgkin Lymphoma and American Indians/Alaska Natives: A SEER Population Study from 2000 to 2012
Authors: Westin Gustavo Figueiredo Marcondes , Go Ronald S. 
Published: October 2019

Abstract
Background: American Indians and Alaska Natives (AI/AN) currently represent approximately 2% of the US population. However, population-based cancer studies are generally limited. Utilizing the Surveillance, Epidemiology and End Results Program (SEER), we investigated the incidence, major subtype distribution, and survival of non-Hodgkin lymphomas (NHL) in the AI/NA population.
Methods: We queried the SEER 2000-2012 database for AI/AN patients with NHL using ICD-O-3 codes 9590-9823. We calculated their incidence rate (case/1,000,000) and trend as well as risk ratios compared to other races, age-adjusted to the US 2000 standard population. Patient level data were extracted to perform summary statistics and calculate overall survival (OS) using STATA/IC 12.1.
Results: We identified 1,135 AI/NA patients with NHL. The average age was 59.6 years (range, 20-85) and 53% were males. The distribution of the major NHL subtypes resembles that seen among the rest of the population and is as follows: diffuse large B-cell (DLBCL; 28%), marginal zone (MZL; 19%), follicular (FL; 13%), small lymphocytic/chronic lymphocytic leukemia (SLL/CLL; 10%), NHL not-otherwise specified (NOS, 4%), mantle cell (MCL; 2%), anaplastic large cell (ALCL; 2%), lymphoplasmacytic (LPL; 1%), and peripheral T-cell (PTCL; 1%). The overall incidence of NHL is 26.4 and did not significantly change over the 12-year study period (Annual Percent Change 0.0, 95% CI [-0.3, 0.3]). Compared to other races, AI/NA have lower incidence of NHL including most of the major subtypes (Table). The median OS for all types of NHL combined is 4.16 years. AI/AN OS is statistically inferior compared to Whites(Figure).
Conclusions: The NHLincidence in AI/NA is lowest among the major race groups and has remained stable in the past 12 years. However their OS is inferior when compared to Whites. The distribution of major NHL subtypes and OS are similar to the rest of the population.
Figure 1. Figure 1.

Disclosures
No relevant conflicts of interest to declare.
Activation of C/EBPa Myeloid-Specific Transcription Factor By NAMPT/SIRT1-Triggered Deacetylation
Authors: Samareh Bardia , Nasri Masoud , Zimmer Inna , Klimenkova Olga , Keller Leonie , Kanz Lothar , Welte Karl , Skokowa Julia 
Published: October 2019

Abstract

Previously, we described new mechanism of G-CSF-triggered granulocytic differentiation of hematopoietic stem cells (HSCs) via activation of the enzyme Nicotinamide Phosphorybosyltransferase (NAMPT) leading to NAD+ production and activation of NAD+ -dependent protein deacetylase sirtuin 1 (SIRT1). We found, that upon stimulation of HSCs with NAMPT, SIRT1 bound to the key myeloid transcription factor C/EBPα followed by transcriptional induction of C/EBPα target genes G-CSFR and G-CSF and granulocytic differentiation.
In the present work we investigated the mechanism of NAMPT/SIRT1-triggered deacetylation of C/EBPα. We found that C/EBPα is acetylated at the position Lys 161, which is evolutionarily conserved. Lys 161 is localized in the transactivation element III (TE-III) of the transactivation domain (TAD) of C/EBPα protein, which is responsible for recruitment of SWI/SNF and CDK2/CDK4. Western blot and DUOLINK analysis using rabbit polyclonal antibody specifically recognizing acetyl-Lys 161 of C/EBPα revealed predominantly nuclear localization of acetylated C/EBPα protein in acute myeloid leukemia cell lines NB4 and HL60 as well as in primary HSCs. Induction of myeloid differentiation of HSCs by treatment with G-CSF as well as ATRA-induced differentiation of NB4 cells resulted in the deacetylation of C/EBPα. NAMPT inhibition in NB4 and HL60 cell lines using specific inhibitor FK866 led to the dramatically elevated levels of acetylated C/EBPα and reduced amounts of total C/EBPα protein, which was in line with diminished mRNA expression of C/EBPα target genes (G-CSF, G-CSFR and ELANE). Interestingly, treatment of acute myeloid leukemia cell line HL60 with NAMPT or transduction of HL-60 cells with NAMPT-expressing lentiviral construct induced myeloid differentiation of these cells even without addition of ATRA. This was in line with time- and dose-dependent increase of total C/EBPα protein levels upon NAMPT treatment. Therefore, NAMPT overcomes transcriptional repression of C/EBPα in HL-60 cells by activation of positive CEBPA autoregulation.
Taken together, we described a new mechanism of regulation of C/EBPα activities in hematopoiesis and leukemogenesis by its post-translational modification via NAMPT/SIRT1-triggered de-/acetylation.

Disclosures
No relevant conflicts of interest to declare.