New inhibitors of glucosylceramide synthase and their effect on cell fate

Abstract Glucosylceramide (GlcCer) is an essential glycosylated lipid found in organisms ranging from fungi to mammals. It is composed of a hydrophilic β-linked glucose and a hydrophobic ceramide, with a predominant content of sphingosine in mammals (d18:1). GlcCer is the precursor of a large scale of different glycosphingolipids. This cerebrozide is synthesized from uridine diphosphate-glucose and ceramide by a GlcCer synthase (UDP-glucose:ceramide glucosyltransferase; UGCG, EC 2.4.1.80). GlcCer-based sphingolipids have been identified as important mediators of a variety of cellular functions and their disequilibrium leads to pathological process development and may induce several diseases progression. Therefore, design of UGCG inhibitor represents an important topic for pharmaceutical research. In this paper, we aimed to study effects of newly synthesized derivatives of (±)-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP, known UGCG inhibitor) on: i) activity of UGCG in vitro; ii) thymocytes viability; iii) calcium transport through plasma membrane of thymocytes; iv) induction of apoptosis and autophagy in thymocytes. Thymocytes were isolated from thymus of three to seven weeks old mice (ICR strain). The key factors influencing the effect of PPMP analogues were their concentration, chemical structure and incubation time. Derivatives were able to change Ca2+ transport already after 15 min of cultivation, but their effects on cell viability were manifested at least after 12 h of cultivation. Four from fifteen studied compounds affected UGCG activity after four hour lasting cultivation, - but without correlation with data relating to effects on calcium transport and/or cell viability. Most potent UGCG inhibitor was chosen and applied for induction of apoptosis and autophagy in thymocytes. This inhibitor induced typical DNA fragmentation and upregulation of LC3B protein as autophagy marker, after 2 h and 4 h cultivation, respectively.

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The Olive Leaves Extract Has Anti-Tumor Effects against Neuroblastoma through Inhibition of Cell Proliferation and Induction of Apoptosis

Nutrients ◽

10.3390/nu13072178 ◽

2021 ◽

Vol 13 (7) ◽

pp. 2178

Author(s):

Fabio Morandi ◽

Veronica Bensa ◽

Enzo Calarco ◽

Fabio Pastorino ◽

Patrizia Perri ◽

...

Keyword(s):

Cell Cycle ◽

Cell Proliferation ◽

Cell Viability ◽

Cell Cycle Progression ◽

Treatment Strategies ◽

Annexin V ◽

Dependent Manner ◽

Induction Of Apoptosis ◽

Dose Dependent

Neuroblastoma (NB) is the most common extra-cranial solid tumor of pediatric age. The prognosis for high-risk NB patients remains poor, and new treatment strategies are desirable. The olive leaf extract (OLE) is constituted by phenolic compounds, whose health beneficial effects were reported. Here, the anti-tumor effects of OLE were investigated in vitro on a panel of NB cell lines in terms of (i) reduction of cell viability; (ii) inhibition of cell proliferation through cell cycle arrest; (iii) induction of apoptosis; and (iv) inhibition of cell migration. Furthermore, cytotoxicity experiments, by combining OLE with the chemotherapeutic topotecan, were also performed. OLE reduced the cell viability of NB cells in a time- and dose-dependent manner in 2D and 3D models. NB cells exposed to OLE underwent inhibition of cell proliferation, which was characterized by an arrest of the cell cycle progression in G0/G1 phase and by the accumulation of cells in the sub-G0 phase, which is peculiar of apoptotic death. This was confirmed by a dose-dependent increase of Annexin V+ cells (peculiar of apoptosis) and upregulation of caspases 3 and 7 protein levels. Moreover, OLE inhibited the migration of NB cells. Finally, the anti-tumor efficacy of the chemotherapeutic topotecan, in terms of cell viability reduction, was greatly enhanced by its combination with OLE. In conclusion, OLE has anti-tumor activity against NB by inhibiting cell proliferation and migration and by inducing apoptosis.

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H2O2 inhibits alveolar epithelial wound repair in vitro by induction of apoptosis

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00177.2003 ◽

2004 ◽

Vol 287 (2) ◽

pp. L448-L453 ◽

Cited By ~ 55

Author(s):

Thomas Geiser ◽

Masanobu Ishigaki ◽

Coretta van Leer ◽

Michael A. Matthay ◽

V. Courtney Broaddus

Keyword(s):

Acute Lung Injury ◽

Epithelial Cells ◽

Lung Injury ◽

Cell Viability ◽

Wound Repair ◽

Wound Edge ◽

Alveolar Epithelial ◽

Induction Of Apoptosis

Reactive oxygen species (ROS) are released into the alveolar space and contribute to alveolar epithelial damage in patients with acute lung injury. However, the role of ROS in alveolar repair is not known. We studied the effect of ROS in our in vitro wound healing model using either human A549 alveolar epithelial cells or primary distal lung epithelial cells. We found that H2O2 inhibited alveolar epithelial repair in a concentration-dependent manner. At similar concentrations, H2O2 also induced apoptosis, an effect seen particularly at the edge of the wound, leading us to hypothesize that apoptosis contributes to H2O2-induced inhibition of wound repair. To learn the role of apoptosis, we blocked caspases with the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp (zVAD). In the presence of H2O2, zVAD inhibited apoptosis, particularly at the wound edge and, most importantly, maintained alveolar epithelial wound repair. In H2O2-exposed cells, zVAD also maintained cell viability as judged by improved cell spreading and/or migration at the wound edge and by a more normal mitochondrial potential difference compared with cells not treated with zVAD. In conclusion, H2O2 inhibits alveolar epithelial wound repair in large part by induction of apoptosis. Inhibition of apoptosis can maintain wound repair and cell viability in the face of ROS. Inhibiting apoptosis may be a promising new approach to improve repair of the alveolar epithelium in patients with acute lung injury.

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p63 sets the threshold for induction of apoptosis using a kinetically encoded ‘doorbell-like’ mechanism

10.1101/681007 ◽

2019 ◽

Author(s):

Jakob Gebel ◽

Marcel Tuppi ◽

Apirat Chaikuad ◽

Katharina Hötte ◽

Laura Schulz ◽

...

Keyword(s):

Dna Damage ◽

Cell Fate ◽

Reproductive Capacity ◽

Structural Mechanism ◽

Cell Fate Decisions ◽

Cell Death Pathways ◽

Induction Of Apoptosis ◽

The Difference ◽

The One

AbstractCell fate decisions such as apoptosis require cells to translate signaling input into a binary yes/no response. A tight control of the process is required to avoid loss of cells by accidental activation of cell death pathways. One particularly critical situation exists in primary oocytes because their finite number determines the reproductive capacity of females. On the one hand a stringent genetic quality control is necessary to maintain the genetic integrity of the entire species; on the other hand an overly stringent mechanism that kills oocytes with even minor DNA damage can deplete the whole primary oocyte pool leading to infertility. The p53 homolog TAp63α is the key regulator of genome integrity in oocytes. After DNA damage TAp63α is activated by multistep phosphorylation involving multiple phosphorylation events by the kinase CK1, which triggers the transition from a dimeric and inactive conformation to an open and active tetramer. By measuring activation kinetics in ovaries and single site phosphorylation kineticsin vitrowith peptides and full length protein we show that TAp63α phosphorylation follows a biphasic behavior. While the first two CK1 phosphorylation events are fast, the third one that constitutes the decisive step to form the active conformation is slow. We reveal the structural mechanism for the difference in the kinetic behavior based on an unusual CK1/TAp63α substrate interaction and demonstrate by quantitative simulation that the slow phosphorylation phase determines the threshold of DNA damage required for induction of apoptosis.

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Effective Targeting of the PI3-K Pathway in CLL with NVP-BEZ235, a Novel Orally Available Dual PI3K/mTOR Inhibitor

Blood ◽

10.1182/blood.v112.11.3166.3166 ◽

2008 ◽

Vol 112 (11) ◽

pp. 3166-3166 ◽

Cited By ~ 1

Author(s):

Medhat Shehata ◽

Susanne Schnabl ◽

Dita Demirtas ◽

Stefanie Tauber ◽

Martin Hilgarth ◽

...

Keyword(s):

Cell Viability ◽

Suspension Cultures ◽

Maximum Effect ◽

Fish Analysis ◽

Therapeutic Concept ◽

Mutational Status ◽

Apoptotic Effect ◽

Induction Of Apoptosis ◽

Induced Apoptosis

Abstract There is growing evidence that the anti-apoptotic PI3-K/Akt pathway is involved in pathogenesis and progression of different types of cancer. We have evidence that PI3-K inhibitors such as LY294002 and wortmannin selectively induce apoptosis in CLL cells (Shehata et al Ab. Blood 2006). Recently, a new orally available PI3-K inhibitor, NVP-BEZ235 has been developed. This competitive ATP binding imidazo-quinoline derivative is already in phase I trials against solid tumors. Here we show, for the first time, the effects of NVP-BEZ235 on the viability of CLL cells in vitro. Primary CLL cells from 37 patients were investigated. Sixteen patients were in Binet stage C, 14 in B and 7 in stage A. Seventeen patients had mutated IgVH genes, 15 had unmutated IgVH and mutation status from 5 patients was not available. Fluorescence in situ hybridization (FISH) analysis showed that 23 patients had del(13q), 9 had del(17p), 8 had del(11q) and 4 patients had trisomy 12. Nineteen patients were untreated and 18 patients were previously treated. To overcome the experimental artifact due to the spontaneous apoptosis of CLL cells in vitro, which may mask the actual effect of the tested drugs, we applied a co-culture model using human bone marrow stromal fibroblasts which supports survival of CLL cells ex vivo. CLL cells were exposed to NVP-BEZ235 at different concentrations (1 nM-10 μM) and incubation times (1, 3, 7 days). Cell viability was assessed by annexin-V/propidium iodide staining, flow cytometry and MTT assays. The results showed that cell viability was significantly higher in co-cultures compared to suspension cultures (the percentage of apoptotic cells after 3 days in co-culture was 5±4 compared to 23±12 in suspension cultures, p< 0,01). NVP-BEZ235 induced apoptosis in the majority of CLL samples under both experimental conditions. However, this effect tends to be more remarkable in co-culture than in suspension: 4-10 fold versus 3-fold increase in apoptosis rate respectively. The pro-apoptotic effect was dose and time dependent and could be observed within 16 hours after incubation at 10 nM. A maximum effect was obtained at a concentration of 5–10 μM. The IC50 values varied between patients and were in a range of 250–750 nM. At these concentrations, NVP-BEZ235 was significantly more effective in induction of apoptosis than LY294002. NVP-BEZ235 inhibited the adhesion of CLL cells to stromal cells suggesting that it may interfere with the survival signal provided by the lymphoid microenvironment in addition to its direct effect on the leukemic cells. FACS analysis demonstrated that NVB-BEZ235 specifically targets the leukemic CD19+ cells while a minimal effect on the viability of T cells and monocytes could be observed. The pro-apoptotic effect of NVP-BEZ235 was independent from the mutational status and cytogenetics. In addition, it induced apoptosis in vitro in CLL cells from patients resistant to fludarabine treatment. In parallel to induction of apoptosis in CLL cells, western blotting demonstrated that NVP-BEZ235 significantly inhibited Akt phosphorylation at Ser-473. This effect was also associated with dephosphorylation (activation) of the tumor suppressor PTEN at Ser-380. DNA microarray analysis using Affymetrix U133A Plus 2.0 GeneChips revealed more than 200 genes which were at least 2 fold up- or down-modulated by NVP-BEZ235 in vitro. These genes include LY9, DUSP10, CCR6, RGS2, IRS2, PI4K2A, ISG20, TFRC, EGR1, HSP90, LCK, TNFRSF17, LYZ, TGFBI and TLR10. In conclusion, the results demonstrate a significant and selective pro-apoptotic effect of NVP-BEZ235 in CLL cells. The data point also to the validity of PI3K-pathway inhibition as a novel therapeutic concept for CLL which should be evaluated in clinical trials.

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5-aza-2’-deoxycytidine induces apoptosis and inhibits tumour growth in vivo of FaDu cells, a specific HPVnegative HNSCC cell line

PLoS ONE ◽

10.1371/journal.pone.0253756 ◽

2021 ◽

Vol 16 (9) ◽

pp. e0253756

Author(s):

Reem Miari ◽

Naiel Azzam ◽

Rinat Bar-Shalom ◽

Fuad Fares

Keyword(s):

Squamous Cell Carcinoma ◽

Cell Viability ◽

Cell Carcinoma ◽

Cancer Cells ◽

Tumour Growth ◽

Xenograft Mice ◽

Induction Of Apoptosis ◽

Fadu Cells

Head and neck cancer squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, resulting in over 600,000 new diagnoses annually. Traditionally, HNCC has been related to tobacco and alcohol exposure; however, over the past decade, a growing number of head and neck cancers are attributed to human papillomavirus (HPV) infection. 5-Aza-2’-deoxycytidine (5-AzaD) was demonstrated as an effective chemotherapeutic agent for acute myelogenous leukaemia. Preclinical data revealed that 5-aza inhibits growth and increases cell death of HPV(+) cancer cells. These effects are associated with reduced expression of HPV genes, stabilization of TP53, and activation of TP53-dependent apoptosis. The aim of the present study is to test the effect of 5-AzaD on growth of human squamous cell carcinoma (FaDu), a HPV(-) and p53 mutated cells, in vitro and in vivo. The effect of 5-AzaD on cell viability, cell cycle progression and induction of apoptosis was tested in vitro. The effect of 5-AzaD on tumour growth in vivo was tested using xenograft mice inoculated with FaDu cells. The results indicated that 5-AzaD reduced cell viability and induced apoptosis in FaDu cells in vitro. In vivo studies revealed that 5-AzaD suppresses the growth of tumours in xenograft mice inoculated with FaDu cells through inhibition of proliferation and induction of apoptosis. These findings may emphasis that 5-AzaD is effective in treatment of HPV(-) HNSCC tumours through TP53 independent pathway. Future studies are needed in order to clarify the molecular mechanism of action of 5-AzaD in HPV(-) cancer cells.

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Sialic acid metabolism as a potential therapeutic target of atherosclerosis

Lipids in Health and Disease ◽

10.1186/s12944-019-1113-5 ◽

2019 ◽

Vol 18 (1) ◽

Cited By ~ 8

Author(s):

Chao Zhang ◽

Jingyuan Chen ◽

Yuhao Liu ◽

Danyan Xu

Keyword(s):

Sialic Acid ◽

Large Scale ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Pathological Process ◽

Neuraminic Acid ◽

Low Density ◽

Epidemiological Surveys

Abstract Sialic acid (Sia), the acylated derivative of the nine-carbon sugar neuraminic acid, is a terminal component of the oligosaccharide chains of many glycoproteins and glycolipids. In light of its important biological and pathological functions, the relationship between Sia and coronary artery disease (CAD) has been drawing great attentions recently. Large-scale epidemiological surveys have uncovered a positive correlation between plasma total Sia and CAD risk. Further research demonstrated that N-Acetyl-Neuraminic Acid, acting as a signaling molecule, triggered myocardial injury via activation of Rho/ROCK-JNK/ERK signaling pathway both in vitro and in vivo. Moreover, there were some evidences showing that the aberrant sialylation of low-density lipoprotein, low-density lipoprotein receptor and blood cells was involved in the pathological process of atherosclerosis. Significantly, the Sia regulates immune response by binding to sialic acid-binding immunoglobulin-like lectin (Siglecs). The Sia-Siglecs axis is involved in the immune inflammation of atherosclerosis. The generation of Sia and sialylation of glycoconjugate both depend on many enzymes, such as sialidase, sialyltransferase and trans-sialidase. Abnormal activation or level of these enzymes associated with atherosclerosis, and inhibitors of them might be new CAD treatments. In this review, we focus on summarizing current understanding of Sia metabolism and of its relevance to atherosclerosis.

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Transformation of cambial tissue in vivo provides an efficient means for induced somatic sector analysis and gene testing in stems of woody plant species

Functional Plant Biology ◽

10.1071/fp06057 ◽

2006 ◽

Vol 33 (7) ◽

pp. 629 ◽

Cited By ~ 18

Author(s):

Kim S. Van Beveren ◽

Antanas V. Spokevicius ◽

Josquin Tibbits ◽

Qing Wang ◽

Gerd Bossinger

Keyword(s):

Cell Fate ◽

Gene Function ◽

Large Scale ◽

Secondary Growth ◽

Wood Formation ◽

Forest Tree ◽

Wound Response ◽

Sector Analysis

Large-scale functional analysis of genes and transgenes suspected to be involved in wood development in trees is hindered by long generation times, low transformation and regeneration efficiencies and difficulties with phenotypic assessment of traits, especially those that appear late in a tree’s development. To avoid such obstacles many researchers have turned to model plants such as Arabidopsis thaliana (L.) Heynh., Zinnia elegans Jacq. and Nicotiana ssp., or have focused their attention on in vitro wood formation systems or in vivo approaches targeting primary meristems for transformation. Complementing such efforts, we report the use of Agrobacterium to introduce transgenes directly into cambial cells of glasshouse-grown trees in order to create transgenic somatic tissue sectors. These sectors are suitable for phenotypic evaluation and analysis of target gene function. In our experiments the wood formation zone containing the cambium of Eucalyptus, Populus and Pinus species of varying age was inoculated with Agrobacterium containing a CaMV 35S::GUS construct. Following an initial wound response, frequent and stable transformation was observed in the form of distinct GUS-staining patterns (sectors) in newly formed secondary tissues. Sector size and extent depended on the cell type transformed, the species and the length of time treated plants were allowed to grow (more than two years in some cases). Induced somatic sector analysis (ISSA) can now be efficiently used to study cell fate and gene function during secondary growth in stems of forest tree species.

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Measuring and Modeling Single-Cell Heterogeneity and Fate Decision in Mouse Embryos

Annual Review of Genetics ◽

10.1146/annurev-genet-021920-110200 ◽

2020 ◽

Vol 54 (1) ◽

pp. 167-187

Author(s):

Jonathan Fiorentino ◽

Maria-Elena Torres-Padilla ◽

Antonio Scialdone

Keyword(s):

Mathematical Modeling ◽

Cell Fate ◽

Large Scale ◽

Living System ◽

In Vitro Models ◽

Cellular Heterogeneity ◽

Mouse Development ◽

Cell Stage ◽

Fate Decision

Cellular heterogeneity is a property of any living system; however, its relationship with cellular fate decision remains an open question. Recent technological advances have enabled valuable insights, especially in complex systems such as the mouse embryo. In this review, we discuss recent studies that characterize cellular heterogeneity at different levels during mouse development, from the two-cell stage up to gastrulation. In addition to key experimental findings, we review mathematical modeling approaches that help researchers interpret these findings. Disentangling the role of heterogeneity in cell fate decision will likely rely on the refined integration of experiments, large-scale omics data, and mathematical modeling, complemented by the use of synthetic embryos and gastruloids as promising in vitro models.

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Epigenetic Regulation in Mesenchymal Stem Cell Aging and Differentiation and Osteoporosis

Stem Cells International ◽

10.1155/2020/8836258 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17 ◽

Cited By ~ 1

Author(s):

Ruoxi Wang ◽

Yu Wang ◽

Lisha Zhu ◽

Yan Liu ◽

Weiran Li

Keyword(s):

Regenerative Medicine ◽

Cell Fate ◽

Large Scale ◽

Functional Decline ◽

Cell Aging ◽

Epigenetic Mechanisms ◽

Reliable Source ◽

Regenerative Therapies

Mesenchymal stem cells (MSCs) are a reliable source for cell-based regenerative medicine owing to their multipotency and biological functions. However, aging-induced systemic homeostasis disorders in vivo and cell culture passaging in vitro induce a functional decline of MSCs, switching MSCs to a senescent status with impaired self-renewal capacity and biased differentiation tendency. MSC functional decline accounts for the pathogenesis of many diseases and, more importantly, limits the large-scale applications of MSCs in regenerative medicine. Growing evidence implies that epigenetic mechanisms are a critical regulator of the differentiation programs for cell fate and are subject to changes during aging. Thus, we here review epigenetic dysregulations that contribute to MSC aging and osteoporosis. Comprehending detailed epigenetic mechanisms could provide us with a novel horizon for dissecting MSC-related pathogenesis and further optimizing MSC-mediated regenerative therapies.

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Targeting BET Bromodomains in Pre-Clinical Models of Burkitt Lymphoma

Blood ◽

10.1182/blood.v128.22.5381.5381 ◽

2016 ◽

Vol 128 (22) ◽

pp. 5381-5381 ◽

Cited By ~ 1

Author(s):

Thomas Ippolito ◽

Juan J Gu ◽

Gregory Tang ◽

Cory Mavis ◽

Rodney R. Miles ◽

...

Keyword(s):

Western Blot ◽

Cell Viability ◽

Cell Line ◽

Cell Lines ◽

Burkitt Lymphoma ◽

Mtor Pathway ◽

Synergistic Activity ◽

Pi3k Activation ◽

Induction Of Apoptosis

Abstract Background: Burkitt lymphoma (BL) is the most common NHL type in children. Although treatment for pediatric BL has improved significantly, there is an urgent need for novel therapies that reduce the toxicity of modern treatment regimens and improve on the dismal survival observed in the relapsed/refractory setting where only about 20-30% of patients survive their disease. Recent reports have implicated co-activation of c-Myc and PI3K in Burkitt lymphomagenesis. Genomic analysis of recurrent oncogenic mutations in BL have identified tonic B-cell receptor signaling and the over-expression of Myc induced microRNAs from the MIR17-92 family, e.g. mir17 and mir19, as possible mechanisms of PI3K activation in BL. Mir17 and mir19, have been implicated in Burkitt lymphomagenesis and their overexpression may be associated with a higher risk of relapse. The protein phosphatase and tensin homolog (PTEN) is a major regulator of PI3K pathway activation. MIR17-92 cluster members have been shown to target PTEN leading to increased PI3K activation. We have previously identified increased expression of mir17 and mir19 along with increased activation of AKT in cell line models of chemotherapy resistant BL suggesting a potential mechanism for increased resistance. BET bromodomains interact with chromatin and enhance transcriptional activation of numerous genes including c-Myc. Thus, BET bromodomains represent a promising target in BL. To investigate the effects of inhibition of c-Myc driven activation of the PI3K/AKT/mTOR pathway, we characterized the activity of the highly potent small molecule bromodomain inhibitor JQ1 in chemotherapy sensitive and resistant BL cell lines. Additionally, we analyzed the ability to enhance anti-lymphoma activity of PI3K/Akt/mTOR pathway inhibition in BL by the combination of BET bromodomain inhibition and targeted inhibition of the PI3K/AKT/mTOR pathway. Methods: The in vitro activity of JQ1 was investigated in the BL cell lines Raji, Raji 4RH (chemotherapy-rituximab resistant), Raji 8RH (rituximab resistant), Ramos, and Daudi. Cell Viability following exposure to JQ1 alone and in combination with the PI3K/mTOR inhibitor omipalisib (GSK458)) was analyzed using Cell-Titer Glo or Alamar Blue assays following 24, 48, and 72 hour exposure over a range of inhibitor concentrations. Induction of apoptosis was analyzed using western blotting for cleaved PARP. C-Myc expression following JQ1 exposure was determined by western blot following 48 hour JQ1 exposure. The effect of JQ1 exposure on the expression of c-Myc induced microRNA expression was determined by qRT-PCR in cells exposed to JQ1 for 48hours. Synergy of combination exposures was determined using CalcuSyn to generate combination index (CI) values. Results: In vitro exposure of BL cell lines to JQ1 for 24, 48, and 72 hours resulted in a significant dose and time dependent decrease in viable cells (72 hour IC50 values: Raji 0.12µM, Raji 4RH 1.7µM, Raji 8RH 0.7µM, Ramos 0.22µM and Daudi 4µM). There was an increase in cleaved PARP after 72 hour exposure indicating induction of apoptosis. While single agent effect was seen in the resistant Raji 4RH cell line, activity was noted to primarily occur at the higher end of the dosing. Western blot analysis demonstrated a reduction in c-Myc expression following exposure to JQ1 1µM for 24 hours (relative band intensity normalized to control: Raji=0.12, Raji 4RH=0.18, Raji 8RH=0.11). qPCR showed a reduction in Mir17 relative transcription levels after 48 hours of exposure to JQ1 2.5mM (relative expression compared to control: Raji=0.72, Raji 4RH=0.98, Raji 8RH=0.83, Ramos=0.57, Daudi=0.46). When combined with omipalisib, an increased effect on cell viability was noted. The combination effect was noted to be synergistic (CI<0.9) at multiple dose combinations while other combinations exhibited primarily additive effects. Conclusion: In vitro inhibition of BET bromodomains with JQ1 results in a decrease in c-Myc expression and a decrease in c-Myc dependent miR expression with impaired proliferation and induction of apoptosis in chemotherapy-sensitive and -resistant BL cell lines. Augmented, and in some cases synergistic, activity is also noted with dual inhibition of BET bromodomains and the PI3K/Akt/mTOR pathway in BL cell lines. Disclosures No relevant conflicts of interest to declare.

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