scholarly journals The Cold-Shock Protein Ybx1 Is Required for Development and Maintenance of Acute Myeloid Leukemia (AML) in Vitro and In Vivo

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 792-792
Author(s):  
Florian Perner ◽  
Ashok K. Jayavelu ◽  
Tina Maria Schnoeder ◽  
Nomusa Mashamba ◽  
Juliane Mohr ◽  
...  
Keyword(s):  
Mouse Model ◽  
Protein Expression ◽  
Malignant Transformation ◽  
Cell Lines ◽  
Median Survival ◽  
Cold Shock ◽  
Rna Binding ◽  
Cold Shock Protein ◽  
Significant Delay

Abstract The family of cold shock proteins (CSPs) is highly conserved and consists of 8 members, including Ybx1-3, Csde1 and Lin28. Ybx1 is a multifunctional DNA/RNA binding protein that modulates gene transcription and translation during inflammation and malignant transformation. Recently, our group identified Ybx1 as a mediator of Jak2 signaling in MPN that protects Jak2-mutated cells from Jak-inhibitor induced apoptosis. In a recently published genome wide CRISPR-Cas9 dropout screen in AML cell lines, depletion of Ybx1 resulted in the highest dropout indices compared to other CSP members, with strongest dependencies in cell lines harboring MLL-rearrangements. Protein expression of Ybx1 in healthy individuals (n=10), primary MDS (n=54) and AML (n=58) bone marrow (BM) biopsies, revealed high protein expression in the majority of AML and MDS cases. Consistently, gene expression data revealed high mRNA expression of Ybx1 in AML samples compared to normal controls. Genetic inactivation of Ybx1 in human AML cell lines by RNAi resulted in reduced proliferative capacity. Therefore, we sought to investigate the requirement for Ybx1 in malignant transformation. We used BM cells from a previously published conventional knockout (ko) mouse model (Lu et al., 2005) in which homozygous deletion is embryonically lethal due to brain malformation. We sorted Lineage-Sca1+Kit+ (LSK-) cells from the BM of heterozygous (Ybx1+/-) and wildtype (Ybx1+/+) mice. Cells were retrovirally infected with either MLL-AF9 (MA9) or HoxA9 and Meis1a (HA9M1) to assess for disease development by serial plating in methylcellulose. Haploinsufficiency for Ybx1 in MA9- or HA9M1 transformed cells limited re-plating capacity to 2-4 rounds. When we injected 2,5x 104 MA9-infected LSK cells into sublethally irradiated recipient mice, recipients of MA9-Ybx1+/- cells (n=8) and MA9-Ybx1+/+ (n=10) showed development of AML. However, recipients of MA9-Ybx1+/- cells had a significant delay in AML development (median survival 67.5 days for Ybx1+/+ versus 101.5 days for Ybx1+/- animals, p=0.0078**). This effect appeared even more pronounced when 1x 106 whole BM cells were transplanted into sublethally irradiated secondary recipients. Besides a significant delay in AML development (median survival 37.5 days for recipients of MA9-Ybx1+/+ versus 79 days for MA9-Ybx1+/- BM, p=0.0042**), disease penetrance was reduced by 40%, indicating that haploinsufficiency for Ybx1 impairs development of MA9 driven AML. In contrast, immunophenotypic abundance of stem- and progenitor cells in Ybx1+/+ versus Ybx1+/- animals revealed comparable numbers in all relevant subpopulations. Serial competitive transplantation of Ybx1+/+ and Ybx1+/- BM into primary and secondary recipient animals showed no competitive disadvantage or lack of self-renewal capacity of Ybx1+/- cells. To address the question whether Ybx1 may also be essential for maintenance of AML, we used RNAi to deplete Ybx1 in already established MA9 driven AML. LSK cells from BL/6 mice transformed with MA9 were injected into primary recipient mice. After AML onset, MA9-LSK cells were sorted and infected with either one of 3 shRNAs against Ybx1 or non-targeting (NT-) control. Lentiviral knockdown of 40% reduced colony formation by more than 50% but did not limit the re-plating capacity in vitro. When injected into sub-lethally irradiated recipient mice, lentiviral knockdown (kd) of Ybx1 resulted in a significant delay in AML development (median survival 39.5 days for NT-control versus 53 days for Ybx1 kd, p=0.0446*). To validate our findings, we used a newly generated conditional ko mouse model for Ybx1, in which exon 3 coding for the cold-shock domain is deleted by activation of an Mx1-Cre-recombinase following pIpC administration. Preliminary results provide first evidence that genetic deletion of Ybx1 after onset of MA9 driven leukemia resulted in improved survival of primary recipient (median survival 73 versus 83 days) and a reduced penetrance in secondary recipient mice. Taken together our results may provide first evidence for a functional role of Ybx1 in MLL-AF9 driven AML. As Ybx1 seems to be dispensable for normal hematopoietic cells, these findings may offer a potential therapeutic index. Experiments to assess for the requirement for Ybx1 in maintenance of murine and human AML as well as analysis on proteomic and transcriptional changes following Ybx1 deletion are currently under way. Disclosures No relevant conflicts of interest to declare.

scholarly journals A Temperature-Independent Cold-Shock Protein Homolog Acts as a Virulence Factor in Xylella fastidiosa

2016 ◽  
Vol 29 (5) ◽  
pp. 335-344 ◽  
Author(s):  
Lindsey P. Burbank ◽  
Drake C. Stenger
Keyword(s):  
Deletion Mutant ◽  
Cold Shock ◽  
Rna Binding ◽  
Xylella Fastidiosa ◽  
Cold Shock Protein ◽  
Plant Colonization ◽  
Wild Type ◽  
Cold Temperatures ◽  
Mrna Stabilization

Xylella fastidiosa, causal agent of Pierce’s disease (PD) of grapevine, is a fastidious organism that requires very specific conditions for replication and plant colonization. Cold temperatures reduce growth and survival of X. fastidiosa both in vitro and in planta. However, little is known regarding physiological responses of X. fastidiosa to temperature changes. Cold-shock proteins (CSP), a family of nucleic acid–binding proteins, act as chaperones facilitating translation at low temperatures. Bacterial genomes often encode multiple CSP, some of which are strongly induced following exposure to cold. Additionally, CSP contribute to the general stress response through mRNA stabilization and posttranscriptional regulation. A putative CSP homolog (Csp1) with RNA-binding activity was identified in X. fastidiosa Stag’s Leap. The csp1 gene lacked the long 5′ untranslated region characteristic of cold-inducible genes and was expressed in a temperature-independent manner. As compared with the wild type, a deletion mutant of csp1 (∆csp1) had decreased survival rates following cold exposure and salt stress in vitro. The deletion mutant also was significantly less virulent in grapevine, as compared with the wild type, in the absence of cold stress. These results suggest an important function of X. fastidiosa Csp1 in response to cellular stress and during plant colonization.

scholarly journals A cold shock protein promotes high-temperature microbial growth through binding to diverse RNA species

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Zikang Zhou ◽  
Hongzhi Tang ◽  
Weiwei Wang ◽  
Lige Zhang ◽  
Fei Su ◽  
...  
Keyword(s):  
High Temperature ◽  
Cold Shock ◽  
Rna Binding ◽  
Cold Shock Protein ◽  
Mrna Accumulation ◽  
Temperature Resistance ◽  
High Temperature Resistance ◽  
Biomass Increase

AbstractEndowing mesophilic microorganisms with high-temperature resistance is highly desirable for industrial microbial fermentation. Here, we report a cold-shock protein (CspL) that is an RNA chaperone protein from a lactate producing thermophile strain (Bacillus coagulans 2–6), which is able to recombinantly confer strong high-temperature resistance to other microorganisms. Transgenic cspL expression massively enhanced high-temperature growth of Escherichia coli (a 2.4-fold biomass increase at 45 °C) and eukaryote Saccharomyces cerevisiae (a 2.6-fold biomass increase at 36 °C). Importantly, we also found that CspL promotes growth rates at normal temperatures. Mechanistically, bio-layer interferometry characterized CspL’s nucleotide-binding functions in vitro, while in vivo we used RNA-Seq and RIP-Seq to reveal CspL’s global effects on mRNA accumulation and CspL’s direct RNA binding targets, respectively. Thus, beyond establishing how a cold-shock protein chaperone provides high-temperature resistance, our study introduces a strategy that may facilitate industrial thermal fermentation.

scholarly journals Interactions of the RNA-Binding Protein Hfq with cspA mRNA, Encoding the Major Cold Shock Protein

2010 ◽  
Vol 192 (10) ◽  
pp. 2482-2490 ◽  
Author(s):  
J. S. Hankins ◽  
H. Denroche ◽  
G. A. Mackie
Keyword(s):  
Cold Shock ◽  
Rna Binding ◽  
Cold Shock Protein ◽  
Regulatory Rna ◽  
Rnase E ◽  
Small Regulatory Rna ◽  
Total Inhibition ◽  
Multiple Copies ◽  
A Site

ABSTRACT CspA, a small protein that is highly induced by cold shock, is encoded by a monocistronic mRNA of 428 nucleotides (nt) whose half-life and abundance are greatly increased following cold shock. We show here that in vitro cspA mRNA can bind multiple copies of Hfq, a hexameric Sm-like protein which promotes a variety of RNA-RNA interactions. Binding of the first Hfq hexamer occurs with an apparent Kd (dissociation constant) of <40 nM; up to seven additional hexamers can bind sequentially at higher concentrations. Known ligands of Hfq, including the small regulatory RNA, RyhB, compete with cspA mRNA. Several experiments suggest that the first binding site to be occupied by Hfq is located at or near the 3′ end of cspA mRNA. The consequences of limited Hfq binding in vitro include nearly total inhibition of RNase E cleavage at a site ∼35 nt from the 3′ end of the mRNA, stimulation of polyadenylation by poly(A) polymerase 1, and subsequent exonucleolytic degradation by polynucleotide phosphorylase. We propose that Hfq may play a facilitating role in the metabolism of cspA mRNA.

scholarly journals Mechanism of MicroRNA-375 Promoter Methylation in Promoting Ovarian Cancer Cell Malignancy

2021 ◽  
Vol 20 ◽  
pp. 153303382098011
Author(s):  
Junjun Shu ◽  
Ling Xiao ◽  
Sanhua Yan ◽  
Boqun Fan ◽  
Xia Zou ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Protein Expression ◽  
Cell Lines ◽  
Cell Invasion ◽  
Promoter Methylation ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Gene Assay ◽  
Cell Malignancy

Objective: Ovarian cancer (OC) ranks one of the most prevalent fatal tumors of female genital organs. Aberrant promoter methylation triggers changes of microRNA (miR)-375 in OC. Our study aimed to evaluate the mechanism of methylated miR-375 promoter region in OC cell malignancy and to seek the possible treatment for OC. Methods: miR-375 promoter methylation level in OC tissues and cells was detected. miR-375 expression in OC tissues and cell lines was compared with that in demethylated cells. Role of miR-375 in OC progression was measured. Dual-luciferase reporter gene assay was utilized to verify the targeting relationship between miR-375 and Yes-associated protein 1 (YAP1). Then, Wnt/β-catenin pathway-related protein expression was tested. Moreover, xenograft transplantation was applied to confirm the in vitro experiments. Results: Highly methylated miR-375 was seen in OC tissues and cell lines, while its expression was decreased as the promoter methylation increased. Demethylation in OC cells brought miR-375 back to normal level, with obviously declined cell invasion, migration and viability and improved apoptosis. Additionally, miR-375 targeted YAP1 to regulate the Wnt/β-catenin pathway protein expression. Overexpressed YAP1 reversed the protein expression, promoted cell invasion, migration and viability while reduced cell apoptosis. Overexpressed miR-375 in vivo inhibited OC progression. Conclusion: Our study demonstrated that demethylated miR-375 inhibited OC growth by targeting YAP1 and downregulating the Wnt/β-catenin pathway. This investigation may offer novel insight for OC treatment.

scholarly journals Csde1 binds transcripts involved in protein homeostasis and controls their expression in erythropoiesis

2017 ◽  
Author(s):  
Kat S Moore ◽  
Nurcan Yagci ◽  
Floris van Alphen ◽  
Nahuel A Paolini ◽  
Rastislav Horos ◽  
...  
Keyword(s):  
Protein Expression ◽  
Mrna Expression ◽  
Mrna Stability ◽  
Cold Shock ◽  
Rna Binding ◽  
Mrna Translation ◽  
Mitochondrial Respiratory Chain ◽  
Protein Homeostasis ◽  
Diamond Blackfan Anemia ◽  
Cold Shock Domain

AbstractExpression of the RNA-binding protein Csde1 (Cold shock domain protein e1) is strongly upregulated during erythropoiesis compared to other hematopoietic lineages. In the severe congenital anemia Diamond Blackfan Anemia (DBA), however, Csde1 expression is impaired. Reduced expression of Csde1 in healthy erythroblasts impaired their proliferation and differentiation, which suggests an important role for Csde1 in erythropoiesis. To investigate the cellular pathways controlled by Csde1 in erythropoiesis, we identified the transcripts that physically associate with Csde1 in erythroid cells. These mainly encoded proteins involved in ribogenesis, mRNA translation and protein degradation, but also proteins associated with the mitochondrial respiratory chain and mitosis. Crispr/Cas9-mediated deletion of the first cold shock domain of Csde1 affected RNA expression and/or protein expression of Csde1-bound transcripts. For instance, protein expression of Pabpc1 was enhanced while Pabpc1 mRNA expression was reduced indicating more efficient translation of Pabpc1 followed by negative feedback on mRNA stability. Overall, the effect of reduced Csde1 function on mRNA stability and translation of Csde1-bound transcripts was modest. Clones with complete loss of Csde1, however, could not be generated. We suggest that Csde1 is involved in feed-back control in protein homeostasis and that it dampens stochastic changes in mRNA expression.

CHIR258, a Novel Multi-Targeted Tyrosine Kinase Inhibitor, for the Treatment of t(4;14) Multiple Myeloma.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 641-641 ◽  
Author(s):  
Suzanne Trudel ◽  
Zhi Hua Li ◽  
Ellen Wei ◽  
Marion Wiesmann ◽  
Katherine Rendahl ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Mouse Model ◽  
Tyrosine Kinase ◽  
Cell Lines ◽  
Small Molecule ◽  
Kinase Inhibitor ◽  
Wild Type ◽  
Myeloma Cells

Abstract The t(4;14) translocation that occurs uniquely in a subset (15%) of multiple myeloma (MM) patients results in the ectopic expression of the receptor tyrosine kinase, Fibroblast Growth Factor Receptor3 (FGFR3). Wild-type FGFR3 induces proliferative signals in myeloma cells and appears to be weakly transforming in a hematopoeitic mouse model. The subsequent acquisition of FGFR3 activating mutations in some MM is associated with disease progression and is strongly transforming in several experimental models. The clinical impact of t(4;14) translocations has been demonstrated in several retrospective studies each reporting a marked reduction in overall survival. We have previously shown that inhibition of activated FGFR3 causes morphologic differentiation followed by apoptosis of FGFR3 expressing MM cell lines, validating activated FGFR3 as a therapeutic target in t(4;14) MM and encouraging the clinical development of FGFR3 inhibitors for the treatment of these poor-prognosis patients. CHIR258 is a small molecule kinase inhibitor that targets Class III–V RTKs and inhibits FGFR3 with an IC50 of 5 nM in an in vitro kinase assay. Potent anti-tumor and anti-angiogenic activity has been demonstrated in vitro and in vivo. We employed the IL-6 dependent cell line, B9 that has been engineered to express wild-type FGFR3 or active mutants of FGFR3 (Y373C, K650E, G384D and 807C), to screen CHIR258 for activity against FGFR3. CHIR258 differentially inhibited FGF-mediated growth of B9 expressing wild-type and mutant receptors found in MM, with an IC50 of 25 nM and 80 nM respectively as determined by MTT proliferation assay. Growth of these cells could be rescued by IL-6 demonstrating selectivity of CHIR258 for FGFR3. We then confirmed the activity of CHIR258 against FGFR3 expressing myeloma cells. CHIR258 inhibited the viability of FGFR3 expressing KMS11 (Y373C), KMS18 (G384D) and OPM-2 (K650E) cell lines with an IC50 of 100 nM, 250 nM and 80 nM, respectively. Importantly, inhibition with CHIR258 was still observed in the presence of IL-6, a potent growth factors for MM cells. U266 cells, which lack FGFR3 expression, displayed minimal growth inhibition demonstrating that at effective concentrations, CHIR258 exhibits minimal nonspecific cytotoxicity on MM cells. Further characterization of this finding demonstrated that inhibition of cell growth corresponded to G0/G1 cell cycle arrest and dose-dependent inhibition of downstream ERK phosphorylation. In responsive cell lines, CHIR258 induced apoptosis via caspase 3. In vitro combination analysis of CHIR258 and dexamethasone applied simultaneously to KMS11 cells indicated a synergistic interaction. In vivo studies demonstrated that CHIR258 induced tumor regression and inhibited growth of FGFR3 tumors in a plasmacytoma xenograft mouse model. Finally, CHIR258 produced cytotoxic responses in 4/5 primary myeloma samples derived from patients harboring a t(4;14) translocation. These data indicate that the small molecule inhibitor, CHIR258 potently inhibits FGFR3 and has activity against human MM cells setting the stage for a Phase I clinical trial of this compound in t(4;14) myeloma.

IPI-504, a Novel, Orally Active HSP90 Inhibitor, Prolongs Survival of Mice with BCR-ABL T315I CML and B-ALL.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2183-2183 ◽  
Author(s):  
Cong Peng ◽  
Julia Brain ◽  
Yiguo Hu ◽  
Linghong Kong ◽  
David Grayzel ◽  
...  
Keyword(s):  
Cell Lines ◽  
Median Survival ◽  
Combination Treatment ◽  
Lymphoblastic Leukemia ◽  
Hsp90 Inhibitor ◽  
Leukemic Cells ◽  
Prolonged Survival ◽  
Hsp90 Inhibition ◽  
T315i Mutation

Abstract Development of mutations within the kinase domain is a major drug-resistance mechanism for tyrosine kinase inhibitors (TKIs) in cancer therapy. In CML (chronic myeloid leukemia), a disease driven by the constitutively active BCR-ABL oncoprotein, no available TKIs have been effective in treating patients with the BCR-ABL T315I mutation. Heat shock protein 90 (Hsp90) is a highly conserved, constitutively expressed molecular chaperone that facilitates folding of client proteins like BCR-ABL, and affects the stability of these proteins. Several labs have shown that Hsp90 inhibition in vitro results in the degradation of BCR-ABL T315I and induces potent killing of these cell lines. However, these results have not been demonstrated in animal models for BCR-ABL-induced CML and B-ALL (B-cell acute lymphoblastic leukemia, a disease that does not respond well to TKIs including imatinib and dasatinib). Thus, IPI-504, an orally administered Hsp90 inhibitor, was evaluated in murine models of CML and B-ALL. Treatment of mice with wild type (WT)- or T315I BCR-ABL-induced CML with IPI-504 resulted in BCR-ABL protein degradation and a decrease in circulating BCR-ABL positive cells. In response to treatment with vehicle the median survival time of WT and T315I CML mice is approximately 20 days. While the T315I CML mice were resistant to imatinib with a median survival of 21 days, IPI-504 (50 and 100 mg/kg, PO TIW) demonstrated dose-dependent prolonged survival of these mice by 30 and 70 days, respectively (p<0.001 for both doses). Both imatinib and IPI-504 similarly prolonged survival of mice with BCR-ABL-WT-induced CML. In the T315I CML mice prolonged survival of the IPI-504 treated cohort was associated with decreased peripheral blood BCR-ABL positive leukemia cells during treatment, less splenomegaly and improved pulmonary histopathlogy at necropsy. In CML mice receiving mixed BCR-ABL-WT- or T315I-transduced donor bone marrow cells, Hsp90 inhibition more potently suppressed T315I-expressing leukemia clones relative to the WT clones, consistent with in vitro studies where T315I BCR-ABL was more sensitive to IPI-504 induced degradation in cell lines than WT BCR-ABL. Combination treatment with IPI-504 and imatinib was more effective than either treatment alone in prolonging survival of mice bearing both WT and T315I leukemic cells. IPI-504 also significantly prolonged survival of B-ALL mice bearing the T315I mutation (p<0.001). These results provide a rationale for use of an Hsp90 inhibitor as a novel approach to overcoming resistance to TKIs as well as the potential for first line combination treatment in CML patients. The potential for IPI-504 to eliminate mutant kinases via Hsp90 inhibition provides a new therapeutic strategy for treating BCR-ABL-induced CML, ALL as well as other cancers resistant to treatment with TKIs.

The Histone Deacetylase (HDAC) Inhibitor Entinostat (SNDX-275) Targets Hodgkin Lymphoma through a Dual Mechanism of Immune Modulation and Apoptosis Induction.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1562-1562 ◽  
Author(s):  
Noor M Khaskhely ◽  
Daniela Buglio ◽  
Jessica Shafer ◽  
Catherine M. Bollard ◽  
Anas Younes
Keyword(s):  
Immune Response ◽  
Cell Death ◽  
Protein Expression ◽  
Cell Lines ◽  
Dependent Manner ◽  
Chemokine Production ◽  
Apoptosis Pathway ◽  
Gene And Protein Expression ◽  
Combination Studies

Abstract Abstract 1562 Poster Board I-585 Purpose SNDX-275 is an oral, class 1 isoform selective HDACi. Phase 1 studies in leukemia demonstrated the agent has a long half-life and that weekly or every other week dosing is sufficient for antitumor activity. Based on recent favorable in vitro and in vivo activity of several HDAC inhibitors in HL, we investigated the in vitro activity of SNDX275 in HL-derived cell lines. Methods For apoptosis and gene expression analysis 05 × 106 cells were incubated with 0.1-2 μM of SNDX-275 for 24-72 hours before they were examined for proliferation and cell death by the MTS assay and the annexin-PI and FACS analysis. For combination studies, cells were incubated with 0.1-2 uM of SNDX-275 and 1-20 nM of either gemcitabine or bortezomib for 48-72 hours. Gene and protein expression were measured by RT-PCR, western blot, and immunohistochemistry. SNDX-275 effects on a panel of 30 cytokines and chemokines was assayed on 05 × 106 cells after incubation of 48 hrs using a multiplex assay. Results SNDX-275 induced cell death in a dose and time dependent manner with an IC50 of 0.4 μM. At the molecular level, SNDX-275 increased H3 acetylation, up-regulated p21 protein expression, and activated the intrinsic apoptosis pathway by down-regulating the anti-apoptotic X-linked inhibitor or apoptosis (XIAP) protein, which was associated with activation of caspase 9 and 3. Combination studies demonstrated that SNDX-275 had synergistic effects when combined with gemcitabine and bortezomib. To further investigate the potential for SNDX-275 activity in HL we measured the effect of SNDX-275 on pathways that may contribute to an anti-tumor immune response. Dysregulated cytokine/chemokine production has been shown to contribute to HL pathology, including immune tolerance of the cancer cells. SNDX-275 increased IL12 p40-70, IP10, and RANTES, and decreased the level of IL13 and IL4, thus favoring Th1-type cytokines/chemokines. In addition, recent data has demonstrated that a variety of epigenetic-modulating drugs may up-regulate the expression of cancer testis tumor associated antigens, leading to a favorable immune response. None of the lines expressed the CTAs without induction. SNDX275 was able to induce CTA expression of SSX2 in L428 but not HDLM2 whereas MAGE-A was induced in both HL cell lines. NY-ESO expression was not induced. Conclusions Our studies demonstrate that SNDS-275 has dual effect on apoptotic and immunomodulatory pathways in HL. Furthermore, this data demonstrates that SNDX-275 may upregulate CTAs suggesting that this treatment may render the tumor more immunogeneic and susceptible to immune mediated killing with tumor-specific cytotoxic T lymphocytes. The selectivity profile of SNDX-275 also suggests that HDAC1 and 2 are the primary targets for HDAC inhibition in these cells. Phase 2 studies with SNDX-275 in HL are ongoing. Disclosures Younes: MethylGene: Honoraria, Research Funding.

NR4A3 Suppresses Lymphomagenesis In Vitro and In Vivo by Induction of Similar Patterns of Pro-Apoptotic Genes like NR4A1

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2728-2728
Author(s):  
Alexander JA Deutsch ◽  
Beate Rinner ◽  
Martin Pichler ◽  
Karoline Fechter ◽  
Hildegard T. Greinix ◽  
...  
Keyword(s):  
Mouse Model ◽  
B Cell ◽  
Cell Lines ◽  
Lymphoma Cell ◽  
Receptor Expression ◽  
Aggressive Lymphoma ◽  
Aggressive Lymphomas ◽  
Apoptotic Genes

Abstract The nuclear orphan receptors NR4A1 and NR4A3 have been demonstrated as cooperating tumour suppressor genes leading to rapid development of acute myeloid leukaemia (AML) in double knock-out mice. In humans, their expression is reduced in leukemic blasts in AML patients. Furthermore, NR4A1 and NR4A3 hypoallelic mice develop preleukemic myelodysplastic/myeloproliferative disorders with progression to AML in some cases. Recently we published a comprehensive study of NR4A nuclear receptor expression levels in lymphoid neoplasms that revealed a marked reduction of NR4A1 and NR4A3 in the majority of patients with B-cell chronic lymphocytic leukaemia, with follicular lymphoma, and with diffuse large B cell lymphoma. Interestingly, functional characterization demonstrated that NR4A1 induces apoptosis of aggressive lymphoma cells in vitro and suppresses tumour growth in a xenograft mouse model. Since the role of NR4A3 in aggressive lymphomas is unknown, we aimed to investigate its etiopathogenic function in these tumors. Low expression of NR4A3 was associated with poor survival in aggressive lymphoma patients. Experimentally, induction of NR4A3 expression by inducible ectopic expression in a variety of lymphoma cell lines led to a significantly higher proportion of apoptotic cells as demonstrated by DNA cleavage, Annexin V staining and increased caspase 3/7 activity. To test the tumor suppressor functions of NR4A3 in vivo, the stably transduced SuDHL4-lymphoma cell line was xenografted in the NOD-SCID-gamma (NSG) mouse model. In this system NR4A3 expression abrogated tumor growth in the NSG mice, whereas vector control and uninduced cells formed massive lymphoid tumors. Pharmacological activation of NR4A3 by Thapsigargin and BF175 resulted in a NR4A3 dependent induction of apoptosis in vitro. To dissect differential transcriptional activity of NR4A3 and NR4A1,both factors were separately over-expressed in four different aggressive lymphoma cell lines followed by semi-quantitative mRNA expression analysis of intrinsic and extrinsic apoptotic genes. NR4A1 or NR4A3 over-expression caused apoptosis by induction of BAK, Puma, BIK, BIM, BID and Trail to the same degree. In summary, our data suggest that NR4A3 possesses tumor suppressive function in aggressive lymphomas by pro-apoptotic transactivation and that NR4A3 is functional redundant to NR4A1 in aggressive lymphomas. Disclosures No relevant conflicts of interest to declare.

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