scholarly journals Re-Wiring BCL-2 Family Anti-Apoptotic Protein Dependencies through Modulating Phosphorylation to Re-Sensitize Venetoclax-Resistant Lymphoid Malignancies to BCL-2 Inhibition

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 35-36
Author(s):  
Stephen Jun Fei Chong ◽  
Mary C Collins ◽  
Liam Hackett ◽  
Matthew S. Davids
Keyword(s):  
Cell Death ◽  
Protein Expression ◽  
Cell Line ◽  
Research Funding ◽  
Family Members ◽  
B Cell Lymphoma ◽  
Prolonged Treatment ◽  
Lymphoid Malignancies ◽  
Phosphatase Inhibitor ◽  
Apoptotic Protein

Introduction Resistance to apoptosis is a hallmark of cancer, and modulation of BCL-2 family proteins is an important mediator of such resistance in hematologic malignancies. Despite the clinical efficacy of the BCL-2 inhibitor venetoclax (VEN), prolonged treatment may lead to resistance, such as the BCL2 G101V mutation (Blombery et al, Blood, 2020); however, over half of VEN resistant cases are not explained by known genetic mechanisms. Phosphorylation of BCL-2 at serine-70 (S70pBCL2) or of MCL-1 at threonine-163 (T163pMCL1) have been shown to increase sequestration of the pro-apoptotic protein BAX (Deng et al, JNCI, 2000) and stabilize the level of anti-apoptotic protein MCL-1 (Wang et al, Mol Cancer, 2014), respectively. We hypothesized that the increase in post-translational modifications of BCL-2 family members, in particular S70pBCL2 and T163pMCL1, are novel mechanisms of functional VEN resistance in lymphoid malignancies. We further hypothesized that the FDA-approved phosphatase activator drug FTY720 (fingolimod) would de-phosphorylate these BCL-2 family members and thereby re-sensitize malignant lymphoid cells to VEN-induced apoptosis. Methods A VEN resistant diffuse large B-cell lymphoma cell line (OCI-Ly1-R) as well as peripheral blood mononuclear cells from 12 previously untreated CLL patients co-cultured with human stromal NK-Tert cells were treated ex vivo with VEN +/- FTY720. A VEN sensitive cell line (OCI-Ly1-S) was treated with VEN +/- a phosphatase inhibitor okadaic acid (OA). Western blot was used to evaluate changes in S70pBCL2 and T163pMCL1 protein levels. BH3 profiling via flow cytometry was performed to determine the survival dependence on anti-apoptotic BCL-2 family members via cytochrome c release in response to specific BH3-only peptides and drugs such as VEN applied directly to mitochondria (Ryan et al, Biol Chem, 2016). Cell viability assays (CellTiter-Glo, Trypan Blue and Annexin/Hoechst) were employed to investigate the effects of FTY720 on OCI-Ly1-R resistance to VEN. The BCL-2-BAX interaction was investigated using co-immunoprecipitation in VEN resistant and sensitive cells following treatment with VEN +/- FTY720. T-test, ANOVA and multiple comparison with a statistical significance set at 2-tailed p ≤ 0.05 were used. Results OCI-Ly1-R cells displayed higher S70pBCL2, T163pMCL1 and MCL-1 expression compared to OCI-Ly1-S cells. Notably, the increase in S70pBCL2 was associated with reduced response of VEN-mediated BCL-2-BAX dissociation, while the increase in T163pMCL1 was accompanied by enhanced MCL-1 protein expression. Using BH3 profiling, we found that the increase in S70pBCL2, T163pMCL1 and MCL-1 expression were functionally associated with a decrease in BCL-2 survival dependence (-79.1%, 1μM VEN, P < 0.0001) and an increase in MCL-1 dependence (+52%, 10μM MS1, P < 0.0001) (Fig. A). The addition of FTY720 reversed these observations in OCI-Ly1-R cells, where we observed a decrease in S70pBCL2, T163pMCL1 and MCL-1 protein expression, BCL-2 and BAX interaction, as well as a "re-wired" functional dependence toward BCL-2 (-21.6% 10μM MS1, +27.9% 1μM VEN, P < 0.0001) (Fig. B). Importantly, pre-treatment with FTY720 re-sensitized OCI-Ly1-R cells to VEN-induced cell death (+56.1%, P = 0.0001) (Fig. C). Conversely, treatment with a phosphatase inhibitor, OA, led to an increase in S70pBCL2, T163pMCL1 and MCL-1 expression as well as reduced late death of OCI-Ly1-S cells (-60%, P = 0.0018). We validated our cell line results in primary CLL cells, and again the combination of FTY720 and VEN similarly reduced S70pBCL2, T163pMCL1 and MCL-1 expression, increased BCL-2 dependence, and enhanced VEN-induced cell death (+23.6%, P < 0.0001). Conclusion Increased S70pBCL2 and T163pMCL1 are associated with VEN resistance, in part by inhibiting VEN-induced BCL-2-BAX dissociation and switching the functional survival dependence from BCL-2 to MCL-1. FTY720 re-sensitizes VEN resistant cells by reducing S70pBCL2, T163pMCL1 and MCL-1 expression, dissociating BAX from BCL-2 and "re-wiring" the survival dependence to BCL-2. These preclinical findings support the exploration of this strategy clinically in patients with VEN resistant lymphoid malignancies. Disclosures Davids: Sunesis: Consultancy; AbbVie: Consultancy; Surface Oncology: Research Funding; Genentech: Consultancy, Research Funding; Eli Lilly: Consultancy; Celgene: Consultancy; AstraZeneca: Consultancy, Research Funding; BeiGene: Consultancy; Ascentage Pharma: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Pharmacyclics: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Verastem: Consultancy, Research Funding; Zentalis: Consultancy; Novartis: Consultancy, Research Funding; Gilead Sciences: Consultancy; Bristol Myers Squibb: Research Funding; Janssen: Consultancy; MEI Pharma: Consultancy, Research Funding; Syros Pharmaceuticals: Consultancy; Merck: Consultancy; Research to Practice: Honoraria.

scholarly journals The Combinatorial Activity of Eftozanermin (ABBV-621), a Novel and Potent TRAIL Receptor Agonist Fusion Protein, in Pre-Clinical Models of Hematologic Malignancies

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 41-41
Author(s):  
Morey L Smith ◽  
Sha Jin ◽  
Dong Chen ◽  
Haichao Zhang ◽  
Jason Huska ◽  
...  
Keyword(s):  
Cell Death ◽  
Fusion Protein ◽  
Cell Line ◽  
Receptor Agonist ◽  
B Cell Lymphoma ◽  
Synergistic Activity ◽  
Trail Receptor ◽  
Phase I Clinical Trials ◽  
Single Chain ◽  
Publicly Traded

Cell death can be initiated through activation of the extrinsic and intrinsic apoptotic signaling pathways. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF superfamily of cytokines, preferentially triggers the extrinsic apoptotic pathway by binding as a trimer to two closely related cell surface death receptors, TRAIL-R1 (DR4) and TRAIL-R2 (DR5). Receptor trimerization leads to the formation of the death-inducing signaling complex (DISC) to recruit and activate downstream caspases that ultimately leads to apoptotic cell death. Because TRAIL signaling induces apoptosis, several TRAIL receptor agonists have been developed for the treatment of cancer. ABBV-621 is a novel, second generation TRAIL receptor agonist that is an engineered fusion protein consisting of an IgG1-Fc linked to a single chain trimer of TRAIL subunits resulting in a total of six death receptor binding sites per molecule to maximize receptor clustering that is currently being tested in Phase I clinical trials (NCT03082209). To expand upon the potential therapeutic utility of ABBV-621, we tested the combinatorial activity of ABBV-621 with numerous standard-of-care (SoC) therapeutics and targeted agents in diffuse large B-cell lymphoma (DLBCL), acute myeloid leukemia (AML) and multiple myeloma (MM) cell lines. Thein vitroresults led to selection of agents to combine with ABBV-621 forin vivostudies. In DLBCL cell line-derived xenograft (CDX) preclinical models, we observed combination activity of ABBV-621 with pevonedistat (PEV) a selective NEDD8 inhibitor. Additionally, synergistic activity was observed with ABBV-621 with either bendamustine (BED) or rituximab (RTX) alone, or BED/RTX together. In AML, we observed compelling combination activity of ABBV-621 with PEV in cell line-derived xenograft (CDX) models. In MM, combination of ABBV-621 plus bortezomib (BTZ) resulted in deeper anti-tumorigenic activity than either agent alone in several CDX models. The pre-clinical data presented here support expanding the indications and settings where ABBV-621 may have utility. A clinical trial assessing the activity of ABBV-621 in combination with bortezomib and dexamethasone in R/R MM patients is planned. Disclosures: All authors are employees of AbbVie. The design, study conduct, and financial support for this research were provided by AbbVie. AbbVie participated in the interpretation of data, review, and approval of the publication. Disclosures Smith: AbbVie:Current Employment, Current equity holder in publicly-traded company.Jin:AbbVie:Current Employment, Current equity holder in publicly-traded company.Chen:AbbVie:Current Employment, Current equity holder in publicly-traded company.Zhang:AbbVie:Current Employment, Current equity holder in publicly-traded company.Huska:AbbVie:Current Employment, Current equity holder in publicly-traded company.Widomski:AbbVie:Current Employment, Current equity holder in publicly-traded company.Bontcheva:AbbVie:Current Employment, Current equity holder in publicly-traded company.Buchanan:AbbVie:Current Employment, Current equity holder in publicly-traded company.Morgan-Lappe:AbbVie:Current Employment, Current equity holder in publicly-traded company.Phillips:AbbVie:Current Employment, Current equity holder in publicly-traded company.Tahir:AbbVie:Current Employment, Current equity holder in publicly-traded company.

MYC Translocations and Expression Are Clinically Important in R-CHOP Treated Patients with De Novo DLBCL.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1100-1100
Author(s):  
Nathalie A. Johnson ◽  
Susanna Ben-Neriah ◽  
Kerry J. Savage ◽  
Tang Lee ◽  
Douglas E. Horsman ◽  
...  
Keyword(s):  
Protein Expression ◽  
B Cell ◽  
Research Funding ◽  
De Novo ◽  
Cell Lymphoma ◽  
Molecular Subtype ◽  
B Cell Lymphoma ◽  
Prognostic Impact ◽  
Statistical Software ◽  
Bcl2 Protein

Abstract Abstract 1100 Poster Board I-122 Background MYC, an oncogene associated with cellular proliferation, is deregulated as a result of chromosomal translocation in Burkitt lymphoma (BL), and in 8-12% of diffuse large B cell lymphomas (DLBCL). In 2006, 2 studies defined the molecular features of BL and DLBCL by gene expression profiling (GEP) (Dave, NEJM 2006; Hummel, NEJM 2006) and identified a subset of cases that resembled DLBCL by morphology, but by GEP, expressed MYC and MYC target genes similar to classical BL, i.e. molecular BL (mBL) signature. The clinical outcome of these cases is poorly defined. More recently, MYC expression and MYC translocations (MYC tr+) have been associated with an inferior overall survival (OS) in de novo DLBCL patients (pts) treated with R-CHOP (Rimsza, Blood 2008; Savage, Blood 2009) but the prognostic impact of BCL2 protein expression and concurrent BCL2 translocations (BCL2 tr+) is poorly understood. We investigated the prognostic impact of the presence of a mBL signature by GEP, high MYC mRNA expression, and the presence of a MYC tr+ with or without a concurrent BCL2 tr+ in DLBCL pts treated uniformly with R-CHOP. Methods 315 samples were reviewed by a panel of expert hematopathologists and classified according to the WHO 2008 criteria. Pts with high grade B cell lymphoma otherwise unclassifiable, BL, primary mediastinal B cell lymphoma (PMBCL), T-cell-rich B cell lymphoma and pts that were not treated with R-CHOP were excluded from this analysis. The remaining 259 DLBCL samples were subjected to GEP as previously described (Lenz, NEJM 2008). Tissue microarrays (TMA) were constructed in cases with available paraffin material. 184 had successful GEP arrays, 186 were included on a TMA and 151 cases were assessed on both platforms. Presence of a mBL signature was determined according to the method described by Dave (NEJM 2006). MYC expression was determined using log normalized expression values from Affymetrix U133 Plus 2.0 probe set id 202431_s_at and dichotomized into high versus low expression using a cut off threshold determined by the statistical software X-Tile (http://www.tissuearray.org/rimmlab/). The presence of MYC tr+ or BCL2 tr+ was determined by fluorescence in situ hybridization (FISH) using MYC and BCL2 breakapart probes (Abbott) on TMAs. BCL2 protein expression was determined by immunohistochemistry (IHC) using clone 124 (Dako). Correlation between variables and association with OS was performed by Pearson Chi-Square, Kaplan-Meier and Cox regression analysis using SPSS statistical software. Results A mBL signature was found in 4/184 samples (2%). One case was MYC tr+, one was MYC tr-, and the MYC translocation status was unknown in the remaining 2 cases. All 4 pts with a mBL had a complete response to R-CHOP lasting >2 years after diagnosis. MYC tr+, BCL2 tr+ or concurrent MYC tr+/ BCL2 tr+ were present in 12%, 20% and 4% of 186 DLBCL cases, respectively. BCL2 tr+ were predominately found in the germinal center B cell (GCB) molecular subtype (36%) compared to the activated B cell (ABC) or unclassifiable (U) subtypes (4% and 19%, p=0.0001) but were not associated with an inferior OS. In contrast, MYC tr+ were not associated with a specific molecular subtype (GCB 15%, ABC 8%, U 19%, p=0.2) but were associated with an inferior OS (p=0.0078). When dichotomizing patients with MYC tr+ according to the BCL2 status, pts with concurrent MYC tr+/ BCL2 tr+ (4%) and pts with MYC tr+ and BCL2 protein-positive biopsies (7%) had a markedly inferior OS compared to pts with MYC tr+ and BCL2 protein-negative biopsies or pts with no MYC tr (median OS 7 months vs. not reached, both p < 0.00001). The presence of MYC tr+ correlated with high MYC expression in 6/16 (38%) MYC tr+ cases whereas high MYC expression was present in 5/111 (5%) MYC tr- cases (p=0.0001). High MYC expression alone was also associated with an inferior OS (p<0.00001). In multivariate analysis, high MYC mRNA expression, concurrent MYC tr+/ BCL2 tr+, and the IPI were independent predictors of OS (p=0.04, p=0.05, p=0.007, respectively). Conclusion MYC expression, as prognostic marker in DLBCL, should be investigated in routine clinical practice. Cytogenetic analysis to determine MYC and BCL2 translocation status by FISH and/or karyotype of de novo DLBCL samples, and BCL2 protein expression by IHC are clinically indicated to identify a group of high-risk pts that may benefit from up-front intensified therapy. Disclosures Connors: Roche Canada: Research Funding. Gascoyne:Roche Canada: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Bcl-xL Protects From UPR-Associated Apoptosis During Plasma Cell Differentiation

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3288-3288
Author(s):  
Brian Gaudette ◽  
Neal N Iwakoshi ◽  
Lawrence H. Boise
Keyword(s):  
Cell Death ◽  
Cell Differentiation ◽  
B Cells ◽  
Er Stress ◽  
B Cell ◽  
Cell Line ◽  
Plasma Cell ◽  
B Cell Lymphoma ◽  
Plasma Cell Differentiation ◽  
Dependent State

Abstract Abstract 3288 Understanding factors that control plasma cell survival is important for the development of therapeutic approaches to diseases including multiple myeloma and autoimmune disorders. As part of the program that allows for B cell differentiation to a plasma cell, a required signal includes the activation of an unfolded protein response (UPR). However unlike stress-induced activation of the UPR, induction of apoptosis does not occur, suggesting that compensatory survival signals are also activated during plasma cell differentiation. The compensatory survival pathways are less defined and require further research. Therefore we employed a model of plasma cell differentiation to better define the survival signaling during this process. The murine B cell lymphoma cell line, Bcl1 can be stimulated to secrete immunoglobulin using IL-5 and LPS. To determine the effects of exogenous ER stress on plasma cell differentiation, we treated the cells with the inhibitor of N-linked glycosylation, tunicamycin, for 5 hours prior to the differentiation signal. The 5 hour pulse of tunicamycin was sufficient to induce significant apoptosis in undifferentiated cells or cells treated with IL-5, resulting in 78% and 74% cell death respectively by 24 hours post treatment. However, if LPS was included in the differentiation stimulus the cells were able to differentiate into IgM-secreting plasma cells with similar kinetics as cells differentiated in the absence of tunicamycin pretreatment. Thus LPS-induced differentiation is sufficient to block ER stress-induced cell death. Since these cells also activate a UPR during differentiation, we hypothesized that part of the differentiation program included protection from UPR-associated cell death. To investigate this effect, we first examined the levels of the antiapoptotic proteins Bcl-2, Bcl-xL and Mcl-1 during plasma cell differentiation. We found that differentiation induced Bcl-xL and caused the loss of Mcl-1. From this data we hypothesized that the differentiation of these cells resulted in Bcl-xL dependence during plasma cell differentiation. To test this we used ABT-737, which selectively blocks the binding pocket of Bcl-xL and Bcl-2 but not Mcl-1 and kills cells that are dependent on Bcl-2 or Bcl-xL. Undifferentiated Bcl1 cells were insensitive to ABT-737 with an IC50 > 2μM. However ABT-737 sensitized LPS-treated Bcl1 cells to tunicamycin pretreatment resulting in 89% death in 24 h compared to 23% in untreated cells. These data suggest that the induction of Bcl-xL is responsible for the survival of cells undergoing ER stress. Most importantly, cells treated with LPS and IL-5 for differentiation became sensitive to ABT-737 with 59% cell death versus 26% in untreated cells, thus demonstrating that during plasma cell differentiation, cells switch to a Bcl-xL-dependent state. To determine the molecular basis for these findings we investigated the effects of ABT-737 on the expression levels of Bcl-2 proteins as well as the effects of differentiation on their interactions. ABT-737 did not induce changes in the expression of Bcl-2 family proteins. However, co-immunoprecipitation demonstrated a shift in Bim binding from Mcl-1 in untreated cells to Bcl-xL in differentiating cells. This latter finding is consistent with a shift from Mcl-1 dependence to Bcl-xL during plasma cell differentiation. To validate these data, primary C57BL/6 splenocytes were isolated, depleted of non-B cells and subsequently stimulated with IL-4 and LPS to differentiate into plasmablasts. Realtime qPCR showed an increase in Bcl-xL mRNA and loss of Mcl-1 and Bcl-2 mRNA in both the primary B cells and the Bcl1 cell line. Western blotting of primary B cell lysates also showed an increase in Bcl-xL protein and loss of Bcl-2 and Mcl-1 protein. Together these data indicate that during plasma cell differentiation the cell enters a Bcl-xL-dependent state that protects against differentiation-induced apoptosis. Disclosures: No relevant conflicts of interest to declare.

Filanesib Primarily Initiates the Apoptotic Program By Activating Bax through a Calpain-Dependent Mechanism

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5353-5353 ◽  
Author(s):  
Susana Hernández-García ◽  
Lorena González-Méndez ◽  
Irena Misiewicz-Krzeminska ◽  
Esperanza Macarena Algarín ◽  
Ana Alicia López-Iglesias ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Research Funding ◽  
Family Members ◽  
Calpain Inhibitor ◽  
Caspase Inhibitor ◽  
Proliferating Cells ◽  
Bax Protein ◽  
Pre Treatment ◽  
Interfering Rna

Abstract Introduction: Filanesib (ARRY-520) is a highly selective inhibitor of kinesin spindle protein (KSP), a microtubule motor protein active in proliferating cells, which plays an essential role in assembly and maintaining of the bipolar spindle. In cells arrested by KSP inhibition, Mcl-1 is rapidly depleted resulting in cell death, and consequently cells that are dependent on this pro-survival protein, such as myeloma cells, are particularly sensitive to filanesib. We investigated the mechanisms underlying the antimyeloma effect of this agent, focusing on other Bcl-2 family members. Methods: In vitro action of filanesib, alone and in combination with calpain inhibitor PD150606, was evaluated in multiple myeloma (MM) cell lines by MTT assay, Annexin V staining and cell cycle profile analysis by flow cytometry. MM cells were transiently transfected with non- targeting control short interfering RNA (NT-siRNA), Bax siRNA ON TARGET plus SMART pool siRNA using the cell line Nucleofector Kit V. Expression levels of different proteins were analyzed by Western-Blot. Results: We previously showed that all 11 MM cell lines tested were sensitive to filanesib and that sensitivity to this agent correlated with Bax levels. For these experiments, we focused on 3 cell lines with different Bax expression and sensitivity to filanesib: OPM-2 and MM1S (sensitive and high Bax levels) and U266 (less sensitive and low Bax levels). Treatment of MM1S with this agent triggered the translocation to the mitochondria of several proapoptotic Bcl-2 family members such as Noxa, Bim and Bax with several downstream effects. The mitochondrial translocation and activation of Noxa is key in the degradation of Mcl-1 by mediating the translocation of this protein from the cytosol to the mitochondria promoting its degradation. Regarding Bim, filanesib also induced the early (12-24 hours) expression of several proapoptotic isoforms of Bim that also translocated to the mytochondria. As previously reported, Bax is the top determinant of sensitivity to filanesib. In the present study, remarkably, once translocated into the mitochondria, Bax was also cleaved into the very potent proapoptotic 18 kDa fragment. All these events triggered the mitochondrial release of cytochrome C (caspase dependent apoptosis) and AIF (caspase independent apoptosis). In order to confirm the role of Bax in filanesib-induced apoptosis, we knocked-down Bax in MM1S by using small interfering RNA. This approach clearly decreased the sensitivity of these cells to filanesib, as treatment with 10 nM for 24 hours induced only 26% apoptosis in the siRNA-Bax cells as compared with 50% in the non-targeted cells (as compared with 58% vs 61% for bortezomib). Furthermore, treatment with filanesib also induced cleavage of effector caspases (3 and 7) in all cell lines studied (OPM2, MM1S, U266). PARP was also cleaved in these cells, but it was previous to caspase activation in the most sensitive cell lines (OPM2, MM1S) suggesting a caspase-independent mechanism of apoptosis. This was confirmed by pre-treatment with the pan caspase-inhibitor Z-VAD-FMK, which did not rescue OPM2 and MM1S cells from apoptosis. Interestingly, one potential mechanism that could link both effects is the activity of calpain, a cysteine protease involved in caspase-independent apoptosis. This protein is a well-known caspase-independent way of processing PARP into the 60 kDa fragment, and has also been described as being responsible for Bax cleavage into the 18-kDa fragment. Consistent with this hypothesis, pre-treatment with the calpain inhibitor PD150606 clearly reduced the activity of filanesib in these cells (35 % to 70 % of survival) as assessed by MTT. Finally, consistent with the previous hypothesis, the less sensitive U266 cell line contained undetectable Bax protein suggesting that filanesib was not able to trigger caspase-independent apoptosis. However, a secondary caspase dependent apoptosis mechanism was confirmed as the pan-caspase inhibitor ZVAD-FMK was able to almost completely abrogate the activity of filanesib. Conclusions: Our results show that filanesib primarily initiates apoptosis by activating Bax in a caspase-independent manner, probably via calpain, a powerful accelerator of the apoptotic process. In addition, Noxa and BIM appear to be crucial for modulating Mcl-1 proteasomal degradation and Bax activation. This work was funded in part by the company Array BioPharma. Disclosures Tunquist: Array BioPharma: Employment. Mateos:Takeda: Consultancy; Onyx: Consultancy; Janssen-Cilag: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Ocio:Mundipharma: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy; Novartis: Consultancy, Research Funding; MSD: Research Funding; Amgen/Onyx: Consultancy, Honoraria, Research Funding; Array BioPharma: Consultancy, Research Funding; Celgene: Consultancy, Honoraria; Pharmamar: Consultancy, Research Funding; Janssen: Honoraria.

ΝFΚΒΙΕ Deletions: A Novel Marker of Clinical Aggressiveness in Primary Mediastinal B-Cell Lymphoma

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 609-609
Author(s):  
Daniel Noerenberg* ◽  
Larry Mansouri* ◽  
Emma Young ◽  
Frick Mareike ◽  
Maysaa Abdulla ◽  
...  
Keyword(s):  
Overall Survival ◽  
B Cell ◽  
High Frequency ◽  
Research Funding ◽  
Cell Lymphoma ◽  
Gene Mutations ◽  
B Cell Lymphoma ◽  
Mutation Status ◽  
Lymphoid Malignancies ◽  
Ann Arbor

Abstract Deregulated NF-κB signaling is a hallmark of most, if not all, lymphoid malignancies, and recurrent gene mutations in both the canonical and non-canonical NF-κB pathway are known to lead to NF-κB activation. However, the full compendium of NF-κB gene mutations in lymphoid malignancies remains to be elucidated. Recently, we reported a 4-bp truncating mutation in the NFKBIE gene, which encodes IκBε, a negative regulator of NF-κB, in patients with chronic lymphocytic leukemia (CLL). The NFKBIE deletion was enriched in clinically aggressive CLL patients (7-8%) and associated with a worse clinical outcome. At the functional level, NFKBIE-deleted CLL showed reduced IκBε levels and decreased p65 inhibition, along with increased phosphorylation and nuclear translocation of p65, compared to wildtype patients. Preliminary data has indicated an increased frequency of NFKBIE aberrations in other lymphoid malignancies as well. To explore this further, we screened for NFKBIE deletions in a large cohort of patients diagnosed with a range of different lymphoid neoplasms. Overall, NFKBIE deletions were identified in 76 of 1414 patients (5.4%). While NFKBIE deletions were relatively infrequent in patients diagnosed with follicular lymphoma (3/225, 1.3%), splenic marginal zone lymphoma (3/175, 1.7%), and T-cell acute lymphoblastic leukemia (1/94, 1.1%), moderate frequencies were observed among diffuse large B-cell lymphoma (18/521, 3.5%), mantle cell lymphoma (8/189, 4.2%), and primary CNS lymphoma (1/34, 2.9%) patients. In contrast, a remarkably high frequency of NFKBIE deletions (41/176 cases, 23%) was observed among primary mediastinal B-cell lymphoma (PMBL) patients. Noteworthy, the prevalence of NFKBIE-deleted PMBL cases was similar in the different contributing centers. All PMBL patients in the present series received a CHOP based treatment regime; in ~75% of cases rituximab was added and ~25% were treated with dose intensified schemes. For the latter, the vast majority of patients received CHOEP, while individual cases were treated with MegaCHOEP, DA-EPOCH or ACVBP. Regarding clinicobiological associations, there were no significant differences between NFKBIE-deleted and wildtype PMBL patients with respect to age, sex, Ann Arbor stage, IPI risk-groups, extranodal or bone marrow involvement, bulky disease, and LDH elevation. However, NFKBIE-deleted patients were more likely to be refractory to primary chemotherapy (31% vs. 3%, P=.001) and had a shorter overall survival compared to wildtype patients (5-year overall survival: 63% vs 84%, P=.013). In multivariate analysis (including age, gender, Ann Arbor stage, IPI, and NFKBIE mutation status), NFKBIE mutation status (95% CI: 1.23-10.61; HR: 3.61; P=0.020) remained an independent factor for poor prognosis. In summary, we document NFKBIE deletions as a common genetic event across B-cell malignancies, albeit at varying frequencies. The high frequency of NFKBIE deletions in PMBL alludes to the critical role of this aberration in the pathophysiology of the disease. NFKBIE deletions were associated witha worse clinical outcome, hence potentially representing a novel poor-prognostic marker in PMBL. *Contributed equally as first authors. **Contributed equally as senior authors. Disclosures Stamatopoulos: Gilead: Consultancy, Honoraria, Research Funding; Abbvie: Honoraria, Other: Travel expenses; Novartis: Honoraria, Research Funding; Janssen: Honoraria, Other: Travel expenses, Research Funding.

Inhibition of expression of anti-apoptotic protein Bcl-2 and induction of cell death in radioresistant human prostate adenocarcinoma cell line (PC-3) by methyl jasmonate

2008 ◽  
Vol 270 (2) ◽  
pp. 277-285 ◽  
Author(s):  
Daniel Ezekwudo ◽  
Rangaiah Shashidharamurthy ◽  
Dilip Devineni ◽  
Erica Bozeman ◽  
Ravi Palaniappan ◽  
...  
Keyword(s):  
Cell Death ◽  
Methyl Jasmonate ◽  
Cell Line ◽  
Prostate Adenocarcinoma ◽  
Human Prostate ◽  
Adenocarcinoma Cell Line ◽  
Adenocarcinoma Cell ◽  
Apoptotic Protein

scholarly journals High Resolution Mapping of Active RNA Polymerases Identifies KIT As a Target of BET Inhibitors in t(8;21) AML

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1225-1225
Author(s):  
Yue Zhao ◽  
Phillip Liu ◽  
Peggy Scherle ◽  
Reid Huber ◽  
Michael R. Savona ◽  
...  
Keyword(s):  
Cell Death ◽  
High Resolution ◽  
Board Of Directors ◽  
Research Funding ◽  
Family Members ◽  
Rna Polymerases ◽  
Model Systems ◽  
Advisory Committees ◽  
Bet Inhibitors ◽  
Depth Analysis

Abstract Background: Bromodomain and extra terminal (BET) family members are being targeted by small molecules in early phase clinical trials for hematopoietic malignancies. These compounds act by binding to the bromodomain of BET family members to block their association with acetylated lysines that are largely on the N-terminal tails of histones. While tool compounds such as JQ1 have been used to show that BET inhibitors impair the transcription of MYC, BCL2 and other oncogenes, only select cell lines are sensitive to these compounds. An in depth analysis of BET family members and the action of these compounds has been complicated by a lack of tools to dissect the effects of these factors on transcription rates rather than steady-state cytoplasmic mRNA pools. Methods: We used precision nuclear run-on transcription sequencing (PRO-Seq) to create high-resolution genomic maps of the locations of all active RNA polymerases (including Pol I, Pol II, and Pol III) before and after treatment with BET inhibitors (BETi). Short treatment times with BETi were used to identify the immediate effects of inhibiting these factors on transcription before compensatory changes occurred. We used Kasumi-1 and SKNO-1 t(8;21) containing AML cells as model systems, as these cells are exceptionally sensitive to these compounds. Results: We found that a 1 hr treatment with BETi caused RNA polymerase pausing within 20-50 bp downstream of the transcription start site in over 1700 genes, including KIT, which is mutated in up to 1/3 of t(8;21) AML. PRO-Seq also identified a 34-kb long eRNA transcribed from what appears to be a group of enhancers 3' to KIT, which was repressed by BETi. KIT protein was dramatically reduced by BETi, suggesting that loss of mutated/amplified KIT contributes to the exceptional response of t(8;21) AML to these drugs. Conversely, over 200 genes showed enhanced transcription in the presence of BETi including MCL1. In addition, BETi repressed the MCL1-targeting microRNAs, MIR29C and MIR29B2. MCL1 protein expression was up-regulated throughout the treatment, suggesting a potential mechanism of resistance to BETi-induced cell death. While comparing the transcriptional effects of different inhibitors of BET family members, INCB054329 was 2-4 fold more potent than JQ1 at inhibiting the growth of Kasumi-1 and SKNO-1 cells Conclusions: Bromodomain inhibition leads to up-regulation of MCL1, which may impair cell death. In addition, BETi leads to dramatic reduction of KIT transcription by INCB054329, and may lend insight to the use of BETi in the treatment of t(8;21) AML, or other AML that contain mutated or amplified KIT. Disclosures Liu: Incyte: Employment. Scherle:Incyte: Employment. Huber:Incyte Corporation: Employment, Equity Ownership. Savona:Incyte Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Astex: Research Funding. Hiebert:Incyte Corporation: Research Funding.

scholarly journals The Impact of Concurrent MYC BCL2 Protein Expression on the Risk of Secondary Central Nervous System Relapse in Diffuse Large B-Cell Lymphoma (DLBCL)

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 495-495 ◽  
Author(s):  
Kerry J. Savage ◽  
Laurie H. Sehn ◽  
Diego Villa ◽  
Roopesh R. Kansara ◽  
Anja Mottok ◽  
...  
Keyword(s):  
Protein Expression ◽  
Research Funding ◽  
Risk Group ◽  
Cumulative Risk ◽  
B Cell Lymphoma ◽  
Risk Groups ◽  
Cns Relapse ◽  
Increased Risk ◽  
Bcl2 Protein ◽  
The Impact

Abstract Introduction: Recent studies have established that concurrent MYC and BCL2 protein expression by immunohistochemistry (IHC) identifies a subgroup of patients with diffuse large B-cell lymphoma (DLBCL) with a poor outcome. Classic dual translocation MYC/ BCL2, so called ‘double hit' disease, is associated with a high risk of central nervous system (CNS) relapse; however the impact of concurrent MYC and BCL2 protein expression on the risk of CNS relapse remains unknown. Further, robust biological markers that accurately predict the risk of CNS relapse in DLBCL would also be of value in clinical practice. Methods: Cases of pre-treatment formalin fixed paraffin embedded DLBCL in two tissue microarrays were independently scored by two expert hematopathologist (GWS and KLT or PF and AM) for expression of MYC (Epitomics Y69), BCL2 (Dako 124), CD10, BCL6 and MUM1 by IHC. MYC and BCL2 positivity were defined as ≥ 40% and ≥ 50% cells with staining, respectively, in accordance with previously established cutoffs (Johnson, JCO 2012; 30). Cases with discordant scores were reviewed by a third hematopathologist (RDG) to reach a consensus. Cell of origin (COO) was assigned according to the Hans IHC algorithm (Hans, Blood 103: 2004) as well as by the recently described gene expression profiling Lymph2Cx 20 gene assay based on NanoString technology (Scott, Blood 2014; 123) in the subset of patients with ≥ 40% tumor content. Patients treated with at least one cycle of R-CHOP chemotherapy with curative intent were included and those with established CNS disease at diagnosis were excluded. Results: 447 patients were identified with the following baseline clinical characteristics: Median age 65 y (16-92y); males n=280, 63%; performance status ≥ 2, n= 147, 33%; stage 3 or 4 disease n=242, 54%; elevated LDH n=219, 47%; EN > 1 n= 80, 17%. With a median follow-up of 6.75 years for living patients, the 3 year time to progression, progression-free and overall survival for all patients were 68%, 66%, and 73%, respectively. In total, 131 (29%) were MYC+BCL2+ and 316 (71%) were non-MYC+BCL2+. By COO assignment using the Hans algorithm (n=444), 192 were non-GCB (43%) and 252 were GCB (57%) and by the Lymph2Cx (n=308); 103 were ABC (33%), 172 were GCB (56%) and 33 (11%) were unclassifiable. The 2 year cumulative risk of CNS relapse for the whole cohort was 4.3%. The cumulative risk of CNS relapse was higher in cases that were MYC+BCL2+ (2 year risk 9.4% vs 2.4%, P=0.001) with similar results obtained if classic MYC+BCL2+ double hit cases are excluded. There were no cases of CNS relapse in cases MYC+ alone by IHC. By COO, patients with a non-GCB phenotype by the Hans algorithm had an increased risk of CNS relapse (2 year risk 6.9% vs 2.6%, P=0.03) and similarly, cases assigned as ABC DLBCL by the Lymph2Cx assay also identified a group with a higher risk of CNS relapse compared to GCB cases (9.5% vs 2.5%, P=0.03) (Figure 1). In Cox regression multivariate analysis including the COO (Hans), IPI group (0/1 vs 2/3 vs 4/5) and MYC/BCL2 IHC, only the IPI (HR 2.18, P=0.02) and MYC+BCL2+ IHC (HR=3.76, P=0.007) were associated with an increased risk of CNS relapse. Similar results were obtained using the Lymph2Cx COO designation. Within the IPI risk groups, MYC+BCL2+ status further stratified patients in the intermediate risk group (IPI 2 or 3, n=206) into a higher risk group (2 year CNS relapse 12.6%) and a low risk group (2 year CNS relapse 2.9%) (P=0.01). A similar trend was observed in the high IPI risk group (IPI 4 or 5, n=86, 2 year CNS relapse MYC+BCL2+ 17.2% vs 4.7%, P=.0.18) but it was not useful in the low IPI risk group (IP1 0 or 1 (n=155), 2 year CNS relapse 4% vs 1%, P=0.39) where the overall risk was low. Within the COO subgroups, MYC+BCL2+ status also defined a group at high cumulative risk of CNS relapse within the non-GCB subtype (12.9% vs 3%, P=0.001) and by the Lymph2Cx defined ABC subtype (16.9% vs 2.2%, P= 0.03) and a trend was observed for GCB defined by Lymph2Cx (6.6% vs 1.5%. P=.08) but not by Hans criteria (P=0.40). Conclusion: Concurrent expression of MYC and BCL2 protein in DLBCL defines a group of patients at high risk of CNS relapse, independent of the IPI and COO. MYC+BCL2+ status may help to further risk stratify patients in the intermediate and high IPI risk groups and within the ABC subtype to identify patients who should undergo additional diagnostic testing and in whom to explore the effectiveness of prophylactic CNS strategies. Figure 1 Figure 1. Disclosures Savage: F Hoffmann-La Roche: Other. Sehn:Roche: Research Funding. Connors:Seattle Genetics, Inc.: Research Funding; Roche: Research Funding. Gascoyne:Hoffman La-Roche: Research Funding.

scholarly journals Characterizing Specificities of Chronic Lymphoid Leukemia Harboring a BCL2 rearrangement

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 29-30
Author(s):  
Charles Herbaux ◽  
Imelda Raczkiewicz ◽  
Kamel Laribi ◽  
Loic Ysebaert ◽  
Agnes Daudignon ◽  
...  
Keyword(s):  
Protein Expression ◽  
Board Of Directors ◽  
Research Funding ◽  
Limit Of Detection ◽  
B Cell Lymphoma ◽  
Advisory Board ◽  
Advisory Committees ◽  
Ras Pathway ◽  
Trisomy 12 ◽  
A Cell

Introduction: Although survival dependence on Bcl2 is a well-known aspect of the pathophysiology of chronic lymphocytic leukemia (CLL), the mechanisms of Bcl-2 dysregulation are incompletely understood. Recurrent translocations involving BCL2 and immunoglobulin genes, including t(14;18)(q32;q21) and variants such as t(2;18) or t(18;22), are classically observed in follicular lymphoma or germinal center diffuse large B-cell lymphoma (GC DLBCL), but are uncommon (&lt;5%) in CLL and usually associated with an indolent clinical course. Here, we characterize the mutational landscape and the functional Bcl-2 family dependencies of BH3 proteins in BCL-2-rearranged (BCL2-R) CLL. We used a functional approach known as BH3 profiling which measures the proximity of a cell to the threshold of apoptosis ("priming") and identifies which anti-apoptotic proteins a cell depends on for survival. Methods: Clinically annotated primary samples from BCL2-R CLL patients identified by karyotype were obtained from the French Innovative Leukemia Organization network and Dana-Farber Cancer Institute. Primary samples from CLL without BCL2 rearrangement were used as a control (ctrl CLL). Next generation sequencing (NGS) was performed using a custom-designed panel of 29 genes, including among others: BIRC3, NOTCH1, FBXW7, MLL2, RAS pathway, SF3B1 and TP53. The mean coverage obtained was 2000X (limit of detection (LOD): 1%). Digital droplet PCR (ddPCR) was used to quantify NOTCH1 c.7544_7545delCT (LOD: 0.025%). Protein expression (Bcl2, Mcl1, Bim) was assessed by Western blot. Baseline BH3 profiling was performed as per Ryan et al., Bio Chem 2016. To mimic the lymph node microenvironment, viability assays were performed in co-culture with the stromal cell line NK.tert. Viability was assessed by AnnexinV/Hoechst staining. Ex vivo drug treatments included: BCL2i (inhibitor): venetoclax; MCL-1i: AZD5991, S63845 and BCLXLi: A133. Statistical analyses were by unpaired and paired t-test with a two-tailed nominal p ≤ 0.05 considered as significant. Results: In our cohort of 110 patients, the median age was 70 years old, and 79% were male. BCL2-R were t(14;18) in 77.2%, t(18;22) in 16.3% and t(2;18) in 6.3% of patients. The translocation involving BCL2 gene was isolated in 23.6% of cases, and was associated with trisomy 12 in 45.4% of patients. The most frequently mutated genes in this cohort were in the NOTCH pathway (NOTCH1 mutation: 43.6 %, mostly subclonal (mean of variant allelic frequency: 6.1%) and FBXW7: 4.5%)) and RAS pathway (KRAS, NRAS, BRAF: 9.1%). BCL2 mutations were observed in 22.8% of the 57 examined cases. No mutation previously described in venetoclax resistant CLL, such as F104L or G101V variant, were observed. Furthermore, MLL2 mutations were observed in 14.5% cases and were significantly associated with complex karyotype (p=0.01) and trisomy 12 (p=0.04). Others mutated genes were: BIRC3 (5.4%), TP53 (3.6%), SF3B1 (1%) and MYD88 L265P(1%). No mutations in EZH2, CREBBP or EP300 were found. In 15 CLL representative samples from each group (BCL2-R and ctrl), Bcl2 protein expression was significantly higher in BCL2-R CLL (ratio Bcl2/actin 0.94 vs 0.74, p=0.009) as was expression of the pro-apoptotic protein Bim (ratio Bim/actin: 2.059 vs 1.524, p=0.007). BH3 profiling demonstrated that BCL2-R CLL and ctrl CLL samples (n=23 in each group) had comparable overall priming (cyto-C release 66.1% vs 63.3%, ns) and Bcl-2 dependence (cyto-C release 75.4% vs 76.3%, ns). Both also had low dependence on Bcl-xL (cyto-C release 8.2% vs 8.8%, ns). In contrast, Mcl-1 dependence was found to be significantly lower in BCL2-R CLL (cyto-C release 15.6% vs 37.4%, p&lt;0.0001). Consistent with our BH3 profiling results, the activity of venetoclax and the Bcl-xLi (A133) did not differ significantly between the 2 groups (n=15). In contrast, both Mcl-1i were less active in the BCL2-R group: average viabilities after 24h treatment with AZD5991 were 76.4% vs 56.3% (p=0.006) and with S63845 77.3% vs 62.9% (p=0.02) in the BCL2-R vs ctrl group, respectively. Conclusion: The genomic landscape of BCL2-R CLL is characterized by a high frequency of trisomy 12, subclonal NOTCH and RAS pathway mutations, as well as BCL2 and MLL2 mutations. Protein expression, BH3 profiling and viability assays data are consistent with nearly exclusive dependence on Bcl-2. Our data suggest that Bcl-2 inhibition should be favored over Mcl-1 inhibition in BCL2-R CLL. Disclosures Herbaux: Roche: Consultancy, Honoraria, Research Funding. Laribi:abbvie: Honoraria, Research Funding; amgen: Research Funding; novartis: Honoraria, Research Funding; takeda: Research Funding. Ysebaert:Roche: Consultancy; Janssen: Consultancy; AbbVie: Consultancy. Morel:Janssen: Honoraria. Guieze:abbvie: Honoraria, Other: advisory board, travel funds; janssen cilag: Honoraria, Other: advisory board, travel funds; roche: Other: travle funds; gilead: Honoraria, Other: travel funds; astrazanecka: Honoraria, Other: advisory board. Brown:Sun: Research Funding; Acerta: Consultancy; Pharmacyclics: Consultancy; Genentech: Consultancy; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other; Invectys: Membership on an entity's Board of Directors or advisory committees, Other: DSMC; Gilead: Consultancy, Research Funding; BeiGene: Consultancy; Catapult: Consultancy; Dynamo Therapeutics: Consultancy; Eli Lilly and Company: Consultancy; Juno/Celgene: Consultancy; Kite: Consultancy; MEI Pharma: Consultancy; Nextcea: Consultancy; Novartis: Consultancy; Octapharma: Consultancy; Pfizer: Consultancy; Rigel Pharmaceuticals: Consultancy; Sunesis: Consultancy; TG Therapeutics: Consultancy; Verastem: Consultancy, Research Funding; Loxo: Consultancy, Research Funding; Astra-Zeneca: Consultancy; Janssen: Honoraria; AbbVie: Consultancy.

scholarly journals Rituximab-Induced CD20-Mediated Signals and Suppression of PI3K-AKT Pathway Cooperates to Inhibit B-Cell Lymphoma Growth By Down-Regulation of Myc.

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5312-5312 ◽  
Author(s):  
Tsuyoshi Nakamaki ◽  
Yuta Baba ◽  
Maasa Abe ◽  
Sou Murai ◽  
Megumi Watanuki ◽  
...  
Keyword(s):  
Protein Expression ◽  
Western Blot ◽  
B Cell ◽  
Cell Line ◽  
Therapeutic Target ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Akt Pathway ◽  
Down Regulation ◽  
Rb Protein

Abstract Rituximab, anti-CD20 monoclonal antibody, shows anti-lymphoma effects by either activating host immune mechanism against lymphoma cells such as ADCC and CDC or suppressing signal(s) important for growth of B-cell lymphoma. Accumulated evidence shows de-regulated PI3K-AKT pathway is important therapeutic target in B-cell lymphoma. Although studies suggested suppression of PI3K-AKT pathway is possibly critical in rituximab-induced anti-lymphoma signals, details of molecular mechanisms covering CD20-mediated signals and PI3K-AKT pathway are still unknown. We analyzed signals in B-cell lymphoma cell line, SD07, which had bi-allelic deletions of both CD20(MS4A1) and PTEN gene. Briefly, SD07 was established from a patient with diffuse large B-cell lymphoma(DLBCL)who showed refractory CD20-negative relapse(Eur.J. Haematol. 2012). We transiently restored protein expression of either or both of CD20 and PTEN by electroporation of expression plasmid having cDNA of those genes in SD07. In this experiment, expression of both proteins were clearly detected by western blot until 72 hours after transfection. CD20 protein was also detectable on cell surface of SD07 cells by flow cytometric(FCM) analysis at comparable levels of those of Daudi cells after transfection on CD20 cDNA. Our previous study showed expression of both c-myc RNA and protein, as judged by FCM, was induced by transient transfection of CD20 cDNA in SD07 cells. Western blot analysis also showed significant increase of myc protein 24hrs after transfection (vector=13.7±0.2, CD20=14.5±0.4, P<0.05, arbitrary density unit) and the increase was not affected by the addition of rituximab(20µg/ml)in culture. In contrast transfection of PTEN cDNA produced significant decrease of myc protein (PTEN=11.2±0.1, P<0.01). Myc protein levels was comparable between cells transfected with CD20 plus PTEN and PTEN alone. However in the presence of rituximab, myc protein expression was markedly downregulated in SD07 cells at both 24 hours(vector=13.7±0.2,CD20+PTEN=8.3±0.1,P=0.0008)and 48hours(vector=12.4±0.3 vs CD20+PTEN=11.2±0.1,P=0.04). 24 hours after transfection, de-phosphorylation and down-regulation of retinoblastoma(RB) protein expression was evident only in SD07 cells transfected with both CD20 and PTEN, but not with either alone. Rituximab also augmented down-regulation of RB protein in SD07 cells transfected with both CD20 and PTEN. After transfection, in vitro cell growth of SD07, as evaluated by MTT, was as follows;vector=4.6±0.3, CD20=4.8±0.3(P=NS), PTEN=4.1±0.2(P<0.05), CD20+PTEN=3.6±0.2(P<0.01), CD20+PTEN+rituximab=2.7±0.2(P<0.01),OD570nm, days3) 72 hours after transfection, by FCM, SD07 transfected with both CD20 and PTEN showed significant increase of subG1 DNA content potion compared with cells transfected with either alone(vector=2.5±0.2%,CD20=5.3±0.2%,PTEN=8.8 ±0.5%,CD20+PTEN= 16.1±0.6, P<0.01). Furthermore, addition of rituximab significantly increase of cells in subG1 in SD07 with transfected with both CD20 and PTEN(18.6±0.5%,P<0.01), suggesting suppression of PI3K-AKT is important for mediateing rituximab-induced apoptotis. Accordance with proliferative effect of CD20 in SD07, transfection of CD20 alone produced significant increase of phosphorylation of AktSer473(vector=11.2±2.3, CD20=13.3±2.3,pAkt/total Akt,P<0.05). Co-transfection of PTEN with CD20 suppress the CD20-induced phosphorylation of Akt in SD07 cells. (CD20+PTEN=12.8±2.3,P=NS). In summary, although data is limited in a cell line, it clearly shows rituximab-induced CD20-mediated signals and suppression of PI3K-AKT pathway by tumor suppressor PTEN cooperatively inhibits growth and induce apoptosis of DLBCL cell line, SD07. Myc protein is critical molecules in this particular cooperative pathways. The present result partly agree studies which showed that inhibition of PI3K-AKT signaling and down-regulation of myc is important in PTEN-induced cytotoxicity in GCB(germinal center B cell)type DLBCL. In addition, we show here myc is not only for PTEN, but also involved in rituximab-induced anti-lymphoma effect. The present result provide a rationale for combination of rituximab and PI3K inhibitor in the treatment of DLBCL. In this context, myc is a candidate of the therapeutic target in rituximab-based immunochemotherapy for B cell lymphoma. Disclosures No relevant conflicts of interest to declare.

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