Impact Of Rad50 On Telomere Recombination Mechanisms In Primary Bone Marrow and B-Cell Lymphomas Lacking Telomerase

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3807-3807
Author(s):  
Tammy Morrish ◽  
Vivek Behera ◽  
Joshua Budman ◽  
Stephen Dria ◽  
Michelle Morgan ◽  
...  
Keyword(s):  
Dna Damage ◽  
B Cell ◽  
B Cell Lymphoma ◽  
Telomere Maintenance ◽  
Model Organisms ◽  
Comparative Genomic ◽  
B Cell Lymphomas ◽  
The Impact ◽  
Dependent Pathway ◽  
In Cells

Abstract The unlimited growth that occurs in tumors requires telomere maintenance. Yet, a portion of human tumors lack telomerase, and maintain telomeres using recombination-based mechanisms. Studies in other model organisms indicate that two different pathways of recombination-based mechanisms impact telomere maintenance and rely on the DNA repair proteins Rad50 and Rad51. In the Rad50-dependent pathway telomere recombination occurs within the telomere repeats. In contrast, recombination using the Rad51-dependent pathway occurs within repetitive sequences in the subtelomeres. Using a mouse B-cell lymphoma model lacking telomerase, Eμmyc+mTR-/-, and immortalized fibroblast cells lacking the RNA component of telomerase (mTR-/-) we have examined the impact of inhibiting Rad50 and Rad51a on telomere recombination. We find inhibiting Rad50 or Rad51a in Eμmyc+mTR-/- B-cell lymphomas, and in mTR-/- immortalized fibroblasts, has a synergistic effect on DNA damage sensitivity to mitomycin but not camptothecin. Inhibiting Rad50 in telomerase deficient cells also results in telomere shortening and in some tumors, reduced growth. In contrast, when Rad50 or Rad51a is inhibited in cells with telomerase, DNA damage sensitivity from mitomycin is not observed when compared to cells expressing a control shRNA. In addition inhibiting Rad50 in cells with telomerase does not significantly impact telomere length or recombination. Next we developed a comparative genomic hybridization (aCGH) approach that detects recombination events in the subtelomeres. Using these subtelomere arrays we find B-cell lymphomas lacking telomerase exhibit a significant increase in subtelomere recombination compared to primary cells. We also examined the impact of inhibiting Rad50 on subtelomere recombination events. Our findings using aCGH suggest that inhibiting Rad50 does not impact subtelomere recombination in Eμmyc+mTR-/- B-cell lymphomas. Overall, our findings suggest that inhibiting either Rad50 or Rad51a in mTR-/- cells has a synergistic impact on the sensitivity to DNA damaging agents in contrast to cells with mTR+/+. Currently we are testing the impact of inhibiting Rad51a on subtelomere recombination. In addition these results further support that Rad50 contributes to telomere recombination mechanisms in tumors lacking telomerase and will provide insight into the mechanism of subtelomere recombination in mammalian cells. Disclosures: No relevant conflicts of interest to declare.

Distinct roles for PARP-1 and PARP-2 in c-Myc-driven B-cell lymphoma in mice

Blood ◽  
2021 ◽  
Author(s):  
Miguel A Galindo-Campos ◽  
Nura Lutfi ◽  
Sarah Bonnin ◽  
Carlos Martínez ◽  
Talia Velasco-Hernandez ◽  
...  
Keyword(s):  
Dna Damage ◽  
B Cells ◽  
B Cell ◽  
Immune Escape ◽  
Cell Lymphoma ◽  
Tumour Progression ◽  
Cancer Therapeutics ◽  
B Cell Lymphoma ◽  
B Cell Lymphomas ◽  
Parp 1

Dysregulation of the c-Myc oncogene occurs in a wide variety of haematologic malignancies and its overexpression has been linked with aggressive tumour progression. Here, we show that Poly (ADP-ribose) polymerase (PARP)-1 and PARP-2 exert opposing influences on progression of c-Myc-driven B-cell lymphomas. PARP-1 and PARP-2 catalyse the synthesis and transfer of ADP-ribose units onto amino acid residues of acceptor proteins in response to DNA-strand breaks, playing a central role in the response to DNA damage. Accordingly, PARP inhibitors have emerged as promising new cancer therapeutics. However, the inhibitors currently available for clinical use are not able to discriminate between individual PARP proteins. We found that genetic deletion of PARP-2 prevents c-Myc-driven B-cell lymphomas, while PARP-1-deficiency accelerates lymphomagenesis in the Em-Myc mouse model of aggressive B-cell lymphoma. Loss of PARP-2 aggravates replication stress in pre-leukemic Em-Myc B cells resulting in accumulation of DNA damage and concomitant cell death that restricts the c-Myc-driven expansion of B cells, thereby providing protection against B-cell lymphoma. In contrast, PARP-1-deficiency induces a proinflammatory response, and an increase in regulatory T cells likely contributing to immune escape of B-cell lymphomas, resulting in an acceleration of lymphomagenesis. These findings pinpoint specific functions for PARP-1 and PARP-2 in c-Myc-driven lymphomagenesis with antagonistic consequences that may help inform the design of new PARP-centred therapeutic strategies with selective PARP-2 inhibition potentially representing a new therapeutic approach for the treatment of c-Myc-driven tumours.

Simultaneous Targeting of SHH/ p53 Pathways in Large B Cell Lymphomas.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1730-1730
Author(s):  
Nikhil S Chari ◽  
Albert E.K. Teo ◽  
L. Jeffrey Medeiros ◽  
Timothy J. McDonnell
Keyword(s):  
B Cell ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
B Cell Lymphoma ◽  
B Cell Lymphomas ◽  
P53 Family ◽  
Shh Pathway ◽  
Drug Concentrations ◽  
Large B Cell ◽  
In Cells

Abstract Abstract 1730 Poster Board I-756 The sonic hedgehog (SHH) pathway, associated with proliferative stem cell niches of many organs, is frequently deregulated in diverse cancers. We have previously shown that the SHH pathway augments the survival of tumor cells by inducing antiapoptotic molecules including bcl-2 and provides resistance to a number of conventional cancer therapies. Aberrant activation of the SHH pathway has been associated with activation and maintenance of lymphoid malignancies. Additionally, our recent data indicates that p63, a p53 family member and an important marker of stem cells has multiple interacting nodes with the SHH pathway. Based on these observations, we hypothesized i) that there is crosstalk between the SHH and p53/p63 networks in cells and, ii) inhibition of the SHH pathway with simultaneous activation of the p53 pathway would result in increased cell death in cancer cell lines of lymphoid origin. Using SDS-PAGE followed by immunoblotting and RT-PCR we surveyed a panel of 18 leukemia/lymphoma cell lines for components of the SHH pathway and the p53/p63/p73 network. Robust SHH pathway expression was observed in 15 of the 18 cell lines examined. Interestingly, in p53 deficient cell lines there was an increase in p63/p73 expression as compared to cell lines with wild type (WT) p53. A set of the previously analyzed diffuse large B- cell lymphoma (DLBCL) cell lines were selected and were representative of both p53 deficient and WT cell lines and also the activated B-like DLBCL (ABC) and germinal center B-like DLBCL (GCB) subgroups. These cells were treated with cyclopamine, an inhibitor of the SHH pathway and/or nutlin, an HDM2 antagonist. Cell viability (MTS assay) was measured using both compounds at various drug concentrations and time points. In addition we also investigated the effects of the drugs individually and in combination on components of the p53/p63 and SHH axes and their targets. Our findings suggest that treatment of p53 (WT) cell lines with a combination of nutlin and cyclopamine results in reduced cell survival than treatment with either drug alone and at lower drug concentrations and that the p53 status of the cell line may be more important in determining therapeutic response to the selected compounds. In addition the p53/p63 pathway may have a novel role in regulation of specific components of the SHH pathway in cells of lymphoid origin. In conclusion, these observations provide proof of concept that a combinatorial therapeutic approach, targeting both the p53 and SHH axes would provide a more robust and favorable response in large B cell lymphomas. Acknowledgments This work was supported in part by the The Mehta Family Foundation Disclosures No relevant conflicts of interest to declare.

Modeling the CNS Tropism of Diffuse Large B-Cell Lymphomas in Vivo

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 576-576
Author(s):  
Maurice Reimann ◽  
Sven Masswig ◽  
Kolja Schleich ◽  
Andrea Herrmann ◽  
Philipp Lohneis ◽  
...  
Keyword(s):  
B Cell ◽  
B Cell Lymphoma ◽  
Gene Set Enrichment Analysis ◽  
Model Systems ◽  
B Cell Lymphomas ◽  
Cns Involvement ◽  
The Impact ◽  
The Brain ◽  
Large B Cell

Abstract Introduction: Central nervous system (CNS) manifestation accounts for dismal prognosis in patients diagnosed with systemic diffuse large B-cell lymphoma (DLBCL). Myc rearrangement, deletions encompassing the CDKN2A (a.k.a. INK4a/ARF) or ATM gene loci as well as NF-kB-hyperactivating mutations are frequently detected in primary and secondary CNS-tropic lymphoma, however, investigations that functionally link these lesions to CNS involvement in adequate in vivo model systems are missing. Methods: We generated primary Eµ-myc transgenic mouse lymphomas with and without distinct naturally occurring NF-kB mutations (within genes encoding for MyD88, CD79B, A20, IkBζ, IkBε or BIRC3) or deletions at the INK4a/ARF and ATM loci by retroviral gene transfer and crossbreeding to the respective knockout strains. A subset of the lymphomas was subjected to gene expression profiling and whole-exome sequencing (WES). Wild-type recipient mice propagated with lymphoma cells via tail vein injection were monitored for systemic lymphoma development, the time at which the brain was isolated and examined regarding lymphoma infiltration. Results: Underlining Myc's role as a putative co-driver of CNS involvement, we found in about 40% of primary Eµ-myc lymphomas (with no additional exogenous lesions) meningeal lymphoma manifestations, and transplantation of the same individual lymphomas into numerous recipients reproduced the CNS lymphoma status. Gene set enrichment analysis of genome-wide transcriptome profiles indicated NF-kB hyperactivation in the CNS-tropic lymphoma group, suggesting that constitutive NF-kB signaling may promote CNS-prone pathogenesis in vivo. Transplantation of Eµ-myc transgenic hematopoietic stem cells expressing a variety of NF-kB-activating mutants in myeloablated recipient mice resulted in a significant acceleration of Eµ-myc -driven lymphomagenesis, with some, but not all of these mutants conferring a CNS-tropic lymphoma phenotype. Global NF-kB suppression in CNS-tropic Eµ-myc lymphomas via the NF-kB-antagonizing IkBΔN super-repressor did not fully abrogate lymphoma infiltration of the brain, suggesting that additional factor(s) must contribute. Accordingly, targeted ablation of the INK4a/ARF and ATM loci robustly enhanced CNS tropism of Eµ-myc lymphomas. Conclusions: The Eµ-myc mouse lymphoma model is well-suited to genetically dissect and rebuild components of DLBCL-like CNS tropism. We identified CDKN2A or ATM deletions as critical determinants of CNS tropism in vivo. Our systematic analyses of different NF-kB mutants - so far rather recognized as functionally interchangeable - indicated that only distinct NF-kB mutants contribute to CNS tropism in B-cell lymphomas. WES data, results from compound genotypes (e.g. combining ATM deletions with an NF-kB-activating mutation), and the impact of the host's cellular immune status will be reported at the meeting. Our findings underscore the need for functional analyses of oncogenic network contexts, and provide important insights into candidate target lesions for personalized CNS-directed therapies in DLBCL patients in the future. Disclosures No relevant conflicts of interest to declare.

scholarly journals Catalytically Active UCH-L1 Is Required for MYC Driven B-Cell Lymphomagenesis

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 644-644
Author(s):  
Tibor Bedekovics ◽  
Sajjad Hussain ◽  
Paul J. Galardy
Keyword(s):  
Catalytic Activity ◽  
B Cell ◽  
Biomarker Discovery ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Striking Similarity ◽  
Biological Knowledge ◽  
B Cell Lymphomas ◽  
Equity Ownership ◽  
The Impact

Abstract Mature B-cell lymphomas are common in children and adults. While increasing biological knowledge has greatly improved the classification of these diseases, the ability to stratify therapy based on this knowledge is limited. As the outcomes for patients with relapsed/refractory disease is poor, it is important to optimize the upfront approach to these patients making enhanced biomarker discovery essential. We recently found that the de-ubiquitinase UCH-L1 is strongly induced in normal GC B-cells, is highly expressed in germinal center type diffuse large B-cell lymphoma, and is a potent prognostic factor associated with poor outcomes in this disease. Using transgenic mice (Uchl1Tg), we observed that deregulated UCH-L1 drives spontaneous B-cell lymphomagenesis and significantly accelerates disease when combined with the Iμ-HABCL6 or Eμ- myc models of GC derived lymphoma. At the molecular level, we showed that UCH-L1 regulates mTOR complex assembly and promotes AKT signaling. It has been alternatively hypothesized that stabilization of mono-ubiquitin is an essential function of UCH-L1 - a mechanism that does not require catalytic activity. To determine the impact of UCH-L1 catalytic activity on lymphoma development, we generated mice carrying a catalytically inactive transgene (Uchl1TgC90A). Consistent with our prior work, we observed that UCH-L1 promotes AKT phosphorylation and suppresses mTORC1 activity towards 4EBP1 and S6K in splenocytes in a manor dependent on catalytic activity. To examine the impact on lymphomagenesis, we crossed Uchl1Tg and Uchl1TgC90A mice with the Eμ- myc model. While we again found the wild-type transgene to accelerate Myc driven lymphoma development, there was no such effect of the C90A construct, indicating that the catalytic activity of UCH-L1 is required for its oncogenic activity. To further examine its role in MYC driven lymphomagenesis we crossed Eμ- myc mice with homozygous null Uchl1 mice and found that Uchl1 loss leads to a significant improvement in lymphoma free survival, indicating that UCH-L1 is a key cooperating factor with MYC in lymphoma. Consistent with this, gene expression profiling from lymphomas arising in Uchl1Tg mice share a striking similarity to those driven by MYC and constitutive PI3 kinase signaling (MYC/P110*) but are distinct from those seen in Iμ-HABCL6 or Lig4 null mice. These data indicate an mechanistic interplay between UCH-L1 and MYC in B-cell lymphoma and suggest that UCH-L1 inhibition may be an effective approach in B-cell lymphomas expressing MYC. Disclosures Galardy: Mission Therapeutics: Research Funding; Abvie: Equity Ownership; Abbot labs: Equity Ownership.

Anticancer Activity of Platinum (II) Complex with 2-Benzoylpyridine by Induction of DNA Damage, S-Phase Arrest, and Apoptosis

2020 ◽  
Vol 20 (4) ◽  
pp. 504-517
Author(s):  
Yu-Lan Li ◽  
Xin-Li Gan ◽  
Rong-Ping Zhu ◽  
Xuehong Wang ◽  
Duan-Fang Liao ◽  
...  
Keyword(s):  
Dna Damage ◽  
B Cell ◽  
Anticancer Activity ◽  
Cancer Cells ◽  
Hepg2 Cells ◽  
Caspase 3 ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
S Phase ◽  
Caspase 9

Objective: To overcome the disadvantages of cisplatin, numerous platinum (Pt) complexes have been prepared. However, the anticancer activity and mechanism of Pt(II) complexed with 2-benzoylpyridine [Pt(II)- Bpy]: [PtCl2(DMSO)L] (DMSO = dimethyl sulfoxide, L = 2-benzoylpyridine) in cancer cells remain unknown. Methods: Pt(II)-Bpy was synthesized and characterized by spectrum analysis. Its anticancer activity and underlying mechanisms were demonstrated at the cellular, molecular, and in vivo levels. Results: Pt(II)-Bpy inhibited tumor cell growth, especially HepG2 human liver cancer cells, with a halfmaximal inhibitory concentration of 9.8±0.5μM, but with low toxicity in HL-7702 normal liver cells. Pt(II)- Bpy induced DNA damage, which was demonstrated through a marked increase in the expression of cleavedpoly (ADP ribose) polymerase (PARP) and gamma-H2A histone family member X and a decrease in PARP expression. The interaction of Pt(II)-Bpy with DNA at the molecular level was most likely through an intercalation mechanism, which might be evidence of DNA damage. Pt(II)-Bpy initiated cell cycle arrest at the S phase in HepG2 cells. It also caused severe loss of the mitochondrial membrane potential; a decrease in the expression of caspase-9 and caspase-3; an increase in reactive oxygen species levels; the release of cytochrome c and apoptotic protease activation factor; and the activation of caspase-9 and caspase-3 in HepG2 cells, which in turn resulted in apoptosis. Meanwhile, changes in p53 and related proteins were observed including the upregulation of p53, the phosphorylation of p53, p21, B-cell lymphoma-2-associated X protein, and NOXA; and the downregulation of B-cell lymphoma 2. Moreover, Pt(II)-Bpy displayed marked inhibitory effects on tumor growth in the HepG2 nude mouse model. Conclusion: Pt(II)-Bpy is a potential candidate for cancer chemotherapy.

scholarly journals Impact of High-Dose Methotrexate on the Outcome of Patients with Diffuse Large B-Cell Lymphoma and Skeletal Involvement

Cancers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2945
Author(s):  
Mélanie Mercier ◽  
Corentin Orvain ◽  
Laurianne Drieu La Rochelle ◽  
Tony Marchand ◽  
Christopher Nunes Gomes ◽  
...  
Keyword(s):  
B Cell ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
High Dose ◽  
High Dose Methotrexate ◽  
Skeletal Involvement ◽  
Large B Cell Lymphoma ◽  
Dose Methotrexate ◽  
The Impact ◽  
Large B Cell

Diffuse large B-cell lymphoma (DLBCL) with extra nodal skeletal involvement is rare. It is currently unclear whether these lymphomas should be treated in the same manner as those without skeletal involvement. We retrospectively analyzed the impact of combining high-dose methotrexate (HD-MTX) with an anthracycline-based regimen and rituximab as first-line treatment in a cohort of 93 patients with DLBCL and skeletal involvement with long follow-up. Fifty patients (54%) received upfront HD-MTX for prophylaxis of CNS recurrence (high IPI score and/or epidural involvement) or because of skeletal involvement. After adjusting for age, ECOG, high LDH levels, and type of skeletal involvement, HD-MTX was associated with an improved PFS and OS (HR: 0.2, 95% CI: 0.1–0.3, p < 0.001 and HR: 0.1, 95% CI: 0.04–0.3, p < 0.001, respectively). Patients who received HD-MTX had significantly better 5-year PFS and OS (77% vs. 39%, p <0.001 and 83 vs. 58%, p < 0.001). Radiotherapy was associated with an improved 5-year PFS (74 vs. 48%, p = 0.02), whereas 5-year OS was not significantly different (79% vs. 66%, p = 0.09). A landmark analysis showed that autologous stem cell transplantation was not associated with improved PFS or OS. The combination of high-dose methotrexate and an anthracycline-based immunochemotherapy is associated with an improved outcome in patients with DLBCL and skeletal involvement and should be confirmed in prospective trials.

scholarly journals Inhibition of Polo-like kinase 4 induces mitotic defects and DNA damage in diffuse large B-cell lymphoma

2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Yi Zhao ◽  
Juan Yang ◽  
Jiarui Liu ◽  
Yiqing Cai ◽  
Yang Han ◽  
...  
Keyword(s):  
Dna Damage ◽  
B Cell ◽  
Therapeutic Potential ◽  
Cell Lymphoma ◽  
Apoptotic Cell ◽  
B Cell Lymphoma ◽  
Predictive Biomarker ◽  
Attractive Potential ◽  
Large B Cell Lymphoma ◽  
Large B Cell

AbstractPolo-like kinase 4 (PLK4), a key regulator of centriole biogenesis, has recently been shown to play key roles in tumorigenesis. Blocking PLK4 expression by interference or targeted drugs exhibits attractive potential in improving the efficacy of chemotherapy. Nevertheless, the role of PLK4 in diffuse large B-cell lymphoma (DLBCL) is still undefined. In this study, we discover that PLK4 is a potential target for the treatment of DLBCL, and demonstrate the efficacy of a PLK4 inhibitor when used in combination with doxorubicin. Pharmaceutical inhibition of PLK4 with CFI-400945 inhibited DLBCL cell proliferation and induced apoptotic cell death. The anti-tumor effects were accompanied by mitotic defects, including polyploidy and cytokinesis failure. Activation of p53 and Hippo/YAP tumor suppressor signaling pathway was identified as the potential mechanisms driving CFI-400945 activity. Moreover, CFI-400945 treatment resulted in activation of DNA damage response. Combining CFI-400945 with doxorubicin markedly delayed tumor progression in DLBCL xenografts. Finally, PLK4 was increased in primary DLBCL tissues and cell lines. High levels of PLK4 expression were associated with poor survival in the patients receiving CHOP-based treatment, implicating PLK4 as a predictive biomarker of DLBCL chemosensitivity. These results provide the therapeutic potential of CFI-400945 both as monotherapy or in combination with doxorubicin for the treatment of DLBCL.

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