bluuebunny/crossref_metadata_2025_split huggingface dataset:
C-Myc Is Required for Acute but Not for Chronic Hematopoietic Malignances in Pten-Null Mice.
Authors: Guo Yinshi , Seet Christopher , Niu Chao , Breslin Peter , Zhang Shubin , Wei Wei , Diaz Manuel , Stiff Patrick , Zhang Jiwang 
Published: October 2019

Abstract
Abstract 1632
Poster Board I-658
c-Myc, the product of an oncogene, is a common target of most leukemic oncoproteins. Deregulation of c-Myc is commonly found in human leukemic blasts. Transgenic over-expression of c-Myc induces myeloid, erythroid, and lymphocytic leukemia in mice, however whether c-Myc is absolutely required for leukemogenesis has not yet been addressed.
Pten, a tumor-suppressing phosphatase, inhibits cell proliferation and promotes apoptotic cell death through repression of PI3K-Akt signaling. Inactivating mutations of Pten and deregulation of PI3K/Akt signaling are both involved in the development of both chronic and acute hematopoietic malignances. Mice with Pten deletions in hematopoietic stem cells (HSCs) develop myeloproliferative disorders (MPD) followed by acute T lymphocytic or myeloid leukemia, reminiscent of disease progression in human chronic myelogenous leukemia. Mice with Pten deletions in lymphocytes develop lymphadenopathy (due to a chronic polyclonal lymphoproliferative disorder) as well as CD4+ T lymphocytic lymphoma. The appearance of these diseases in one animal model provides an opportunity to study the pathogenesis of multiple diseases simultaneously.
To study whether c-Myc is required for the development of these hematopoietic disorders in Pten-mutant mice, we generated inducible Pten and c-Myc double-knockout mice (Pten-/-c-Myc-/-). By comparing the hematopoietic phenotypes of the Pten-/-c-Myc-/- mice with those of Pten-mutant (Pten-/-) mice, we found that both sets of mice developed MPD and lymphadenopathy, however none of the compound-mutant mice developed acute leukemia or lymphoma. Interestingly, in contrast to the MPD which developed in Pten-/- mice, which is dominated by granulocytes, megakaryocytes predominate in the MPD of Pten-/-c-Myc-/- mice.
We have concluded that c-Myc is required for the development of both T lymphocytic lymphoma and the acute leukemic transformation of Pten-/- MPD, but is not essential for the development of chronic myeloid or lymphoid proliferative disorders. Our study suggests that deregulation of PI3K/Akt signaling in Pten-mutant hematopoietic cells protects these cells from apoptotic cell death, which results in chronic proliferative disorders, while the deregulation of c-Myc resulting from additional mutations promotes hematopoietic cell proliferation and blockage of maturation, and is absolutely required for the development of acute hematopoietic malignances.

Disclosures
No relevant conflicts of interest to declare.
Characterization of Treg Subpopulations in Chronic Lymphocytic Leukemia Using 15 Color Flow Cytometry.
Authors: Biancotto Angelique , Fuchs John Chris , Dagur Pradeep , Wiestner Adrian , McCoy J. Philip 
Published: October 2019

Abstract
Abstract 1644
Poster Board I-670
CD4+ regulatory T cells (Treg) act to suppress activation of the immune system and thereby maintain immune system homeostasis and tolerance to self-antigens. Tregs have been shown to be increased in the peripheral circulation of patients with various types of cancer including CLL and have been postulated to play a role in inhibition of anti-tumor immune responses. 15 color staining was performed on mononuclear cells isolated from peripheral blood from 33 healthy controls and 12 patients with chronic lymphoid leukemia (CLL). Treg cells were defined as viable CD45+ CD3+ CD8- CD4+ CD25+ Forkhead box P3+ (FoxP3)+ mononuclear cells. Among the Treg population we defined 4 sub-populations; Naïve Treg (CD45-RA+ CD27+ CD197+), Effector Treg (CD45-RA- CD27- CD197-), Central memory Treg (CD45-RA- CD27+ CD197+) and Effector memory Treg (CD45-RA- CD27+ CD197-). We report level of expression of activation markers CD39, HLA-DR and CD38 and IL-7 receptor CD127 on Treg subsets as defined above. The percentage of Treg was increased significantly in CLL patients compared with healthy controls 12.8±1.3% vs 5.7±0.3% (p<0.0001). In healthy controls, the majority of Treg are CD45-RA- (80.2±2.9 %) whereas in CLL patients, we observed Treg cells in both CD45-RA- and CD45-RA+ populations (62.6±4.9% and 40.4±5% respectively). Inside the CD45-RA+ populations, we showed that there was a significant higher proportion of naïve Treg among CLL patients compare to healthy controls ((83.8±5% and 41.8±5% respectively (p<0.0001)). Among the CD45-RA- populations, there was no significant difference in the proportion of each memory subtypes. We observed a different pattern of activation among the Treg in CLL patients, naïve Treg expressed more CD39 and HLA-DR compare to healthy controls (2x to 3x fold increase, p<0.0001), but less CD38. In central memory subpopulation, CD39 and CD127 expressions were increased in Treg isolated from CLL patients (p=0.04 and p=0.01 respectively), whereas CD38 was decreased (p=0.01). In effector memory population, HLA-DR expression was lower in CLL patients compared to healthy control (3±0.9% and 9.8±0.8% respectively, p<0.0001). Finally, in the effector subpopulation, HLA-DR expression was also decreased in Treg from CLL patients (p<0.0001). In summary, in these studies, we showed proportions of naïve and memory Treg as well as a different activation pattern of Treg cells present in CLL patients compared to healthy controls. The assessment of complex patterns of sub-phenotype expression in diseases vis a vis healthy individuals should expand our ability to understand the intricacies of both adaptive and innate cellular immune responses and their dysregulation in cancer patients.

Disclosures
No relevant conflicts of interest to declare.
The Tak-1 Inhibitor AZ-Tak1 Inhibits XIAP, Activates Caspase-9, and Induces Apoptosis in Mantle Cell Lymphoma.
Authors: Buglio Daniela , Palakurthi Sangeetha , Byth Katharine F. , Younes Anas 
Published: October 2019

Abstract
Abstract 1692
Poster Board I-718
Transforming growth factor-b-activated kinase 1 (TAK1) is a key regulator of NF-kB activation. TAK1 can be activated by a variety of pro-inflammatory cytokines and T and B cell receptors. Recent experiments demonstrated that deletion of TAK1 results in inactivation of both JNK and NF-kB signaling resulting in massive apoptotic death of hematopoietic cells in mice. In this study, we examined the expression pattern of TAK1 and its role as a potential therapeutic target for lymphoma. First, we examined TAK1 expression in a panel of lymphoid cell lines by western blot, and found it to be highly expressed in mantle cell lymphoma cell lines (Mino, SP53, and Jeko-1). These lines expressed relatively low levels of the tumor suppressor protein A20. Mino and SP53 expressed high level of p-p38. Subsequently, we investigated the in vitro activity of the novel TAK1 small molecule inhibitor AZ-Tak1 in these cell lines. AZ-Tak1 is a potent and a relatively selective inhibitor of TAK1 kinase activity, with an IC50 of 0.009 mM. It also inhibits Jak2 but at a much higher concentration (IC50=0.18 mM). AZ-Tak1 treatment decreased the level of p38 and ERK in mantle cell lymphoma cells, and induced apoptosis in a dose and time dependent manner, with an IC50 of 0.1-0.5 mM. Using the annexin-V and PI staining and FACS analysis, After 48 hours of incubation, AZ-Tak1 (0.1 mM) induced apoptosis in 28%, 34% and 86% of Mino, SP53, and Jeko cells, respectively, which was increased to 32%, 42%, and 86% when 0.5 mM concentration was used. Similar activity was also observed when primary mantle cell lymphoma cells were examined. Using pathway-specific protein arrays focusing on apoptosis, kinases, and transcription factors, AZ-Tak1 (0.5 mM) altered the level of several proteins that regulate cell growth and survival, especially members of the inhibitors of apoptosis (IAP) family. Specifically, AZ-Tak1 decreased the level of SMAC/DIABOLO and cytochrome –C in the mitochondria, which was associated with a decrease in the level of the anti-apoptotic protein X-linked IAP (XIAP) and activation of the intrinsic apoptotic pathway as evident by activation of caspase 9, cleavage of caspase 3, and induction of apoptosis. Furthermore, and consistant with its ability to inhibit Jak2 activity, AZ-Tak1 reduced STAT2 and STAT6 levels. AZ-Tak1 demonstrated no significant effect on bcl-2 family members. Finally, co-treatment with HDAC inhibitors demonstrated synergistic effect with low concentrations of AZ-Tak1. Collectively, our data demonstrate that targeting TAK1 by the small molecule inhibitor AZ-Tak1 induces cell death in mantle cell lymphoma by activating the intrinsic apoptosis pathway, suggesting that targeting TAK1 may have a therapeutic value for the treatment of mantle cell lymphoma.

Disclosures
Palakurthi: Astra Zeneca: Employment. Byth:Astra Zeneca : Employment.
Overall Survival (OS) Benefit of Rituximab Based Immunochemotherapy Followed by Post-Induction Treatment in Mantle Cell Lymphoma (MCL): a Retrospective Analysis of 279 Patients Treated by Polish Lymphoma Research Group (PLRG) Centers.
Authors: Jurczak Wojciech , Szymczyk Michal , Giza Agnieszka , Joks Monika , Kisiel Elzbieta , Stella-Holowiecka Beata , Boguradzki Piotr , Wrobel Tomasz , Sikorska Magdalena , Knopinska-Posluszny Wanda , Kalinka-Warzocha Ewa , Walewski Jan , Skotnicki Aleksander B. 
Published: October 2019

Abstract
Abstract 1702
Poster Board I-728

Background
ASCT consolidation in the first remission is the treatment of choice in MCL patients. However lack of adequate response to the first line therapy, elderly age and co-existing co-morbidities makes it feasible for less than a third of patients.

Methods
Retrospective analysis of 279 MCL cases treated at 10 PLRG centers was performed: 52% of them (144 pts) received Rituximab in induction therapy; 35% (97 pts) were subjected to post-induction therapy (ASTC – 16%, radioimmunotherapy consolidation – 13% and Rituximab maintenance – 6%). There were no significant differences in risk factor distribution among analyzed subgroups.

Results
1) At 5 years OS was 40% in the whole group: 77% for those subjected to post-induction therapy vs 25% for those who were not; 5 year PFS is 20%, 48% and 5% respectively (p<0,0001, in both comparisons).
2) Pts with initial good response, whose treatment was NOT continued after induction, had inferior results (5 year OS and PFS – 30 and 10 % respectively) to those subjected to post-induction therapy (p<0,0001).
3) Rituximab included in the first line regimens increased RR, increasing % of pts that could be subjected to post-induction therapy: progression/ death during the first line therapy were 5,5% (8/144 Rituximab treated pts) as compared to 15,5% (21/135 treated without Rituximab).

Conclusions
With all limitations of retrospective analysis, it strongly supports the necessity of Rituximab immunochemotherapy followed by post induction treatment in MCL pts. The role of ASCT is established in younger patients, radioimmunotherapy consolidation or Rituximab maintenance should be considered in elderly and unfit ones.

Disclosures
No relevant conflicts of interest to declare.
The Flt3 ITD Accelerates An Already Established Myeloid Leukemia and Alters Chemotherapy Response In Vitro and In Vivo in a p53 Dependent Manner.
Authors: Pardee Timothy , Zuber Johannes , Lowe Scott 
Published: October 2019

Abstract
Abstract 1719
Poster Board I-745
Acute myeloid leukemia (AML) is an aggressive disease with heterogeneous genetics and variable prognosis. The presence of an internal tandem duplication within the FLT3 gene (Flt3 ITD) is a marker for poor prognosis and has been linked to anthracycline resistance in cell lines and primary patient samples in vitro. The effect of this mutation on response to chemotherapy in vivo has not been examined and its effect on response to cytarabine is not known. In this study we use a genetically defined mouse model of AML to examine the effects of the Flt3 ITD on response to cytarabine and the anthracycline doxorubicin in vitro and in vivo. In vitro the Flt3 ITD conferred resistance to doxorubicin and the combination of doxorubicin and cytarabine but sensitivity to cytarabine alone in comparison to the identical leukemia without the Flt3 ITD. In vivo the presence of the Flt3 ITD provided an advantage in leukemic engraftment and accelerated disease onset. This advantage could be partially reversed by treatment of the animals with cytarabine but not by treatment with doxorubicin. Surprisingly, in vivo the Flt3 ITD conferred a marked increase in sensitivity to cytarabine when compared to the parental leukemia without this mutation. In contrast to the parental leukemia, the addition of doxorubicin to cytarabine provided no advantage over cytarabine alone. When the DNA damage response was assessed the presence of the Flt3 ITD resulted in an increase in the levels of p53 following treatment with either doxorubicin or cytarabine. Induction of the p53 target genes p21 and MDM2 was also increased. Surprisingly, the Flt3 ITD had no effect on disease onset or chemotherapy response in vitro or in vivo in the setting of p53 null AML. These data when taken together demonstrate that the Flt3 ITD confers a mixed sensitivity and resistance to standard chemotherapy and provides an engraftment advantage in a manner that depends on an intact p53 allele. This may at least in part explain the rarity of dual p53 null and Flt3 ITD positive AML. Furthermore, these data suggest that patients with Fl3 ITD positive AML may benefit more from treatment with high dose Ara-C then with combinations containing an anthracycline.

Disclosures
No relevant conflicts of interest to declare.
Valproic Acid Selectively Inhibits STAT3 Phosphorylation.
Authors: Zhu Shiguo , Denman Cecele J , Lee Dean A. 
Published: October 2019

Abstract
Abstract 1720
Poster Board I-746
Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor (1), was found to enhance NK cell mediated antitumor activity by upregulating the surface expression of NKG2D ligands MICA and MICB on hepatoma cells (2). In contrast, VPA was found to impair NK cell antitumor activity by downregulating the surface expression of NKp30 and NKp46 on NK cells by blocking NFkB activation (3). Recently, we also found that VPA efficiently upregulates the surface expression of MICA, MICB, and ULBP family ligands on human osteosarcoma and neuroblastoma cells, but downregulates NKG2D surface expression on human NK cells. Similarly, the HDAC inhibitor MS275 efficiently upregulates expression of MICA, MICB, and ULBP family ligands on human osteosarcoma and neuroblastoma cells, but surprisingly, MS275 significantly upregulates NKG2D expression on NK cells. In addition, we found that VPA inhibited the cell growth of osteosarcoma cell lines more readily than MS275. To investigate the mechanism of these differing effects of VPA and MS275, we compared the effect of these HDAC inhibitors on Signal Transducer and Activator of Transcription (STAT) signaling, which are important signaling pathways in NK cells and many cancers. Here we show that VPA is a potent inhibitor of STAT3 phosphorylation at the tyrosine 705 residue in NK cells, whereas MS275 has no effect on STAT3 phosphorylation (Figure A). Moreover, this inhibition is highly specific, as VPA has no effect on STAT1 and STAT5 phosphorylation (Figure B). To further confirm VPA-mediated STAT3 inhibition, we detected STAT3 expression and the degree of tyrosine phosphorylation affected by VPA in a panel human osteosarcoma cells. We found that constitutive STAT3 phosphorylation is present in osteosarcoma SaOS2 and LM7 cells, but not in OS187 cells, which corresponded to the stronger growth inhibition caused by VPA in SaOS2 and LM7 cells compared to OS187 cells. These results are for the first to show that VPA, a HDAC inhibitor, is also a selective STAT3 inhibitor. VPA can upregulate NKG2D ligand expression on the tumor cell surface by HDAC inhibition, but may downregulate NKG2D expression on the NK cell surface by STAT3 inactivation. The antitumor activity of VPA may be via a mechanism of both HDAC inhibition and STAT3 inactivation. The knowledge of potent STAT3 inhibition by VPA is important for identifying potential new clinical applications for this drug.

Disclosures
No relevant conflicts of interest to declare.
Akt Inhibitors Induce Apoptosis in Chronic Lymphocytic Leukemia Cells.
Authors: de Frias Mercè , Iglesias-Serret Daniel , Cosialls Ana M , Coll-Mulet Llorenç , Santidrián Antonio F , González-Gironès Diana M , de la Banda Esmeralda , de Sevilla Alberto Fernandez , Pons Gabriel , Gil Joan 
Published: October 2019

Abstract
Abstract 1731
Poster Board I-757
Phosphatidylinositol-3-kinase (PI3K)/Akt pathway has been described to be critical in the survival of chronic lymphocytic leukemia (CLL) cells. Here, we have analyzed the effect of two selective chemical inhibitors of Akt (Akti-1/2 and A-443654) in the survival of CLL cells. We studied by cytometric analysis the cytotoxic effects of Akt inhibitors on peripheral B and T lymphocytes from patients with CLL and from healthy donors. Both inhibitors induced apoptosis in CLL cells in a dose-dependent manner. Moreover, B cells from CLL samples were more sensitive to Akt inhibitors than T cells from CLL samples, and B or T cells from healthy donors. Survival factors for CLL cells, such as IL-4 and SDF-1a, were not able to block the apoptosis induced by both Akt inhibitors. We studied the changes induced by Akti-1/2 and A-443654 at mRNA level by performing reverse transcriptase multiplex ligation–dependent probe amplification (RT-MLPA). Akti-1/2 did not induce any change in the mRNA expression profile of genes involved in apoptosis, while A-443654 induced some changes, including an increase in NOXA and PUMA mRNA levels, suggesting the existence of additional targets for A-443654. We also studied the changes induced by both Akt inhibitors in some BCL-2 protein family members on CLL cells by Western blot. Both inhibitors induced an increase in PUMA and NOXA protein levels, and a decrease in MCL-1 protein level. Moreover, Akti-1/2 and A-443654 induced apoptosis irrespective of TP53 status. These results demonstrate that Akt inhibitors induce apoptosis of CLL cells and might be a new therapeutic option for the treatment of CLL.

Disclosures
No relevant conflicts of interest to declare.
Molecular and Biological Characteristics of Acquired Vorinostat-Resistant Cutaneous T-Cell Lymphoma Cells.
Authors: Zhang Chunlei , Zhang Xiang , Li Baoqiang , Duvic Madeleine 
Published: October 2019

Abstract
Abstract 1732
Poster Board I-758
Vorinostat (suberoylanilide hydroxamic acid, SAHA), a pan-histone deacetylase (HDAC) inhibitor, has an overall response rate of 24-30% in two phase II studies of patients with cutaneous T cell lymphoma (CTCL). Since a considerable proportion of CTCL patients did not reach a partial response and loss of response could occur after only a few months, development of resistance became an important clinical problem. Although we have shown that constitutive activation of STAT signaling may be involved in resistance to vorinostat, the other mechanisms of resistance to vorinostat in CTCL are largely unknown. To further investigate mechanisms of vorinostat resistance, we have generated a vorinostat-resistant CTCL cell line (HH/VOR) from a parent vorinostat-sensitive HH CTCL cell line by long term exposure to stepwise increasing concentrations of vorinostat. The HH parental cells were cultured in increasing concentrations of vorinostat starting at 10 nM. Viable cells were then passaged into a higher concentration of vorinostat in 10 nM increments until a concentration of 1 μM vorinostat was reached. The HH/VOR cells were then maintained in complete RPMI1640 medium containing 1 μM vorinostat. We studied the molecular and biological characteristics of the vorinostat-resistant CTCL cells. Compared with the parental vorinostat-sensitive HH cells, the vorinostat-resistant HH/VOR cells were highly resistant to vorinostat-mediated growth inhibition and apoptosis. Of interest, the HH/VOR also exhibited cross resistance to another pan-HDAC inhibitor panobinostat and a class I HDAC inhibitor SNDX-275. The vorinostat-resistant HH/VOR cells had reduced accumulation of acetylated histones (H3 & H4) and decreased expression of class I and class II HDACs (1-11), and no expression of multi-drug resistant (MDR) efflux transporters. Moreover, the vorinostat-resistant HH/VOR cells had elevated DNA binding of NF-κB and increased expression of phospho-NF-κB p65 and phospho-STAT-1 compared with the parent sensitive HH cells. Co-treatment with the RXR-selective retinoid bexarotene selectively enhanced vorinostat-induced apoptosis in the vorinostat-sensitive HH and -resistant HH/VOR CTCL cell lines as well as in patients' Sézary cells compared to normal CD4+ T-cells. Taken together, our findings provide further evidence for the potential of vorinostat to cause acquisition of HDAC inhibitor resistance in CTCL. This acquired HDAC inhibitor resistance neither correlates with over-expression of HDACs nor with expression of MDR but correlates with abnormal activation of the NF-κB and STAT-1. Bexarotene may override this acquired resistance of CTCL cells to vorinostat and other HDAC inhibitors.

Disclosures
Zhang: Merck: Research Funding. Duvic:Merck: Honoraria, Research Funding, Speakers Bureau.
A Meta-Analysis of Randomized Controlled Trials of Aspirin in Primary Prevention of Cardiovascular Disease.
Authors: Raju Nina C , Sobieraj-Teague Magda , Eikelboom John W 
Published: October 2019

Abstract
Abstract 174
Primary prevention with aspirin reduces the risk of non-fatal cardiovascular events but has not been demonstrated to reduce mortality. We performed an updated meta-analysis of randomised controlled trials of aspirin in primary prevention to obtain best estimates of the benefits and harm of aspirin compared with no aspirin with a focus on mortality. Eligible articles were identified by computerized search of MEDLINE, EMBASE, Cochrane library and CINAHL databases, review of bibliographies of relevant publications and a related article search using PubMed. The outcomes of interest included all cause mortality, cardiovascular mortality, the composite of myocardial infarction, stroke or death, and bleeding. 2 reviewers independently extracted study information and data. Data were pooled from individual trials using the DerSimonian-Laird random-effects model and results are presented as relative risk (RR) and 95% confidence intervals (CI). 8 studies comprising a total of 96,726 subjects were included. Aspirin reduced all-cause mortality (RR 0.94; 95%CI 0.88–1.00), the composite of myocardial infarction, stroke or cardiovascular death (RR 0.87; 95%CI 0.82–0.93), and myocardial infarction (RR 0.8; 95%CI 0.66–0.98) but did not significantly reduce cardiovascular mortality (RR 0.94; 95%CI 0.82–1.08) or stroke (RR 0.93; 95%CI 0.81–1.07). Aspirin increased the risk of major bleeding (RR; 1.69 95%CI 1.38–2.08), gastrointestinal bleeding (RR 1.38; 95%CI 1.16–1.65) and hemorrhagic stroke (RR 1.36; 95%CI 1.01–1.84). There was no interaction between subjects with or without diabetes for the outcomes of all cause mortality, cardiovascular mortality, the composite of myocardial infarction, stroke or death. Aspirin therapy in subjects with no prior history of cardiovascular disease reduces the risk of cardiovascular events, myocardial infarction and overall mortality. These benefits are achieved at the expense of increased bleeding.

Disclosures:
No relevant conflicts of interest to declare.