Atypical Protein Kinase C λ/I Oncogenic Signaling through the Chromatin Modifier Satb2 Is Required for Leukemic B-Cell Progenitor Differentiation Arrest and Leukemogenesis

Abstract The molecular mechanisms that control leukemic transformation in B-cell acute lymphoblastic leukemia remain unclear. Leukemic stem cells/progenitors (LSC/P) hijack common pathways utilized by hematopoietic stem cells/progenitors (HSC/P) while they also activate other unique pathways that result in increased self-renewal and differentiation arrest susceptible of therapeutic intervention. A major regulator of HSC self-renewal vs differentiation is the distribution of polarized cell fate determinants. Atypical protein kinase C (aPKC)-ζ and aPKCi in humans or its homologue aPKCλ in mice are the catalytic components of the apical polarity complex PAR3-PAR6. aPKCs have also been argued to function as tumor suppressors. We have previously shown that the genetic deficiency of aPKC activity is dispensable for normal HSC/P activity (Sengupta A et al., PNAS 2011). We had found that primary human and murine BCR-ABL+ LSC/P have ~2-3 fold increased activation of aPKCλ/i. To investigate the possible role of aPKCs in LSC/P activity, we utilized a lymphoid blast-crisis chronic myelogenous leukemia model and evaluated the role aPKCζ and aPKCλ inducible deficiency in leukemic progression. After leukemia induction resulting from doxcycycline withdrawal in Scl-tTA/TRE-BCR-ABL mice that were also transgenic for Mx1Cre, aPKCζ-/- and/or aPKCλflox/flox, leukemic mice (dox-off) were treated with polyI:C to induce deletion of aPKCλ. aPKCλΔ/Δ LSC (Lin-cKit+Sca1+CD135-CD34-) and progenitors (CFU-C) of transplanted recipient mice were 40 and 87% reduced, respectively, suggesting a critical role of aPKCλ in the maintenance of LSC/P. Upon serial transplantation of bone marrow (BM) from CML animals, all WT and aPKCζ-/- recipient mice died by 6-10 weeks of B-ALL. However, mice transplanted with aPKCλΔ/Δ or aPKCζ-/-;aPKCλΔ/Δ BM cells did not die after serial transplantation followed for over one year, despite maintaining leukemic B-cells in circulation and hematopoietic tissues with catalytically active BCR-ABL expression. Leukemic ProB/PreB cells deficient in aPKCλ activity showed ~67% reduced proliferation and 2-fold higher apoptosis than WT and aPKCζ deficient ProB/PreB cells while non-leukemic aPKCλ deficient B-cell lymphopoiesis was grossly normal. Similarly, shRNA-mediated knock-down of aPKCi, in CML patient derived LSC/P led to reduced proliferation, increased apoptosis and enhanced differentiation indicating that aPKCi is also required for the survival and maintenance of human LSC/P. Strikingly, the B-cell differentiation program was restored in aPKCλΔ/Δ mice with expansion of IgM expressing B cells. Downstream, the activation of CrkL, MEK/ERK and Myc signaling pathways were attenuated in absence of aPKCλ in leukemic B-progenitor cells. Unlike non-leukemic B-cell progenitors, the transcriptome of aPKCλ-deficient leukemic B-progenitors showed up-regulation of the B-lymphoid differentiation gene network (Pax5, Ebf1, Ikzf1, Ikzf2, Ikzf3, Rag1 & Rag2). Interestingly, Myc protein expression was reduced and the cell fate determinant Numb mislocalized in aPKCλΔ/Δ leukemic B-cell progenitors, with predominant nuclear distribution. The mRNA/protein expression of Satb2, a chromatin modifier controlling Myc and Numb expression as well as B-cell differentiation, was significantly reduced in aPKCλ-deficient leukemic B-cell progenitors while the expression of its antagonist Satb1 was unchanged. Chromatin immunoprecipitation analysis of leukemic B-cell progenitors showed ~16-200 fold increased enrichment of Satb2 binding to promoter sequences of Cdkn2a and B-cell differentiation genes Pax5 and Ebf1 over non-leukemic B-cell progenitors. Finally, forced expression of Satb2 in aPKCλΔ/Δ deficient LSC/P rescued leukemic proliferation and B-cell differentiation arrest in vivo indicating that Satb2, downstream of aPKCλ, is required for BCR-ABL+ LSC/P activity. Taken together, these data indicate that aPKCλacts as an oncogene in leukemic B-cell progenitors. Loss of aPKCλ reduces LSC/proB proliferation and survival, and restores B-cell differentiation through combined reduction of MAPK activation, Numb mislocalization and differential expression/activity of the chromatin modifier Satb2. This data defines the role of aPKCλ in LSC/P activity and identifies aPKCλ as a new target for pharmacological intervention dispensable for normal lympho-hematopoiesis. Disclosures Cancelas: US Army Medical Research and Material Command (Award W81XWH-15-C-0047) / Department of Defense: Research Funding; Terumo BCT: Research Funding; Cellphire, Inc.: Membership on an entity's Board of Directors or advisory committees; Cerus Corporation: Research Funding; Citra Labs, Inc.: Research Funding; Leukemia & Lymphoma Society of North America: Research Funding; William & Lawrence Hughes Foundation: Research Funding; Haemonetics, Inc.: Research Funding; National Institutes of Health: Research Funding; New Health Sciences, Inc.: Membership on an entity's Board of Directors or advisory committees.

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Modeling of the Epigenome of the Cell-of-Origin Identifies Cancer-Specific DNA Methylation Patterns in CLL

Blood ◽

10.1182/blood-2018-99-115941 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 3885-3885

Author(s):

Justyna Anna Wierzbinska ◽

Reka Toth ◽

Naveed Ishaque ◽

Jan-Phillip Mallm ◽

Karsten Rippe ◽

...

Keyword(s):

Dna Methylation ◽

Cell Differentiation ◽

B Cells ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

B Cell Differentiation ◽

Advisory Committees ◽

Normal Differentiation ◽

Methylation Patterns

Abstract Normal B cells undergo extensive epigenetic programming during normal differentiation and distinct B cell differentiation stages represent unique DNA methylation patterns. Chronic Lymphocytic Leukemia (CLL) originates from rapidly differentiating B cells and their DNA methylation signature is stably propagated in CLL. Consequently, CLL methylome data can be used to infer the putative cell-of-origin (COO) for each individual CLL case. We define the COO of CLL as the cell that has acquired a first oncogenic hit and which will initiate tumorigenic growth if one or more additional hits have been acquired. This means that two factors contribute to the epigenetic profile of CLL cells: first, the epigenetic profile of the founder B cell at the time of malignant transformation and second, CLL-specific epigenetic alterations that are acquired during leukemogenesis and progression of the disease. Previous studies using peripheral blood CD19+ B cells as a reference for aberrant methylation calls completely neglected the massive epigenetic programming that occurs during normal B cell differentiation. Thus, novel strategies aiming at identifying truly CLL-specific methylation changes considering the highly dynamic methylome during normal B cell differentiation were urgently needed. Here we outline a new analytical framework to delineate CLL-specific DNA methylation. We demonstrate how this approach can be applied to detect epigenetically deregulated transcripts in CLL. Firstly, we modeled the epigenome dynamics occurring during normal B cell differentiation using linear regression. The DNA methylomes of CLL cells were then precisely positioned onto the normal B cell differentiation trajectory to define the closest normal B cell methylome for every CLL patient, the COO. The epigenome of the COO then served as a reference for aberrant DNA methylation calls. We dissected two categories of CLL-specific methylation events: those occurring at sites undergoing epigenetic programming during B cell differentiation and those that normally do not change during B cell differentiation. The first group was further subdivided into class A and B, displaying exaggerated methylation loss or gain, respectively, and class C showing both hyper- and hypomethylation relative to the normal differentiation. The second group was classified into class D displaying hypo- and class E showing hypermethylation. Overall, only 1.6% of the CpG-sites (7,248 CpGs) represented on the Illumina 450k array were affected by disease-specific methylation programming, mostly hypomethylation (6,680 CpGs). Next, the molecular programs underlying the CLL-specific methylation patterns were investigated. We tested enrichment of chromatin states and of transcription factor binding sites (TFBS) as identified in an immortalized B cell line (GM12878). This indicated that disease-specific methylation events target transcriptionally relevant cis-regulatory elements in CLL (enhancers, weak and poised promoters and insulator regions). In line with this, CLL-specific differentially methylated regions affected TFBS associated with signaling pathways known to be important in normal B-cell differentiation (i.e. BATF, EBF1). We also observed altered methylation at CTCF binding sites suggesting their involvement in CLL pathogenesis. In the present work, we dissected CLL methylomes to distinguish between normal B cell differentiation-associated methylation patterns and CLL-specific methylation events. We showed that this approach is indispensable to identify key pathogenic events driving CLL pathogenesis. The relevance of our approach was demonstrated by contrasting the number of epigenetically deregulated miRNAs and protein-coding genes to those determined with a classic analysis using CD19+ B cells as controls. This highlights the extent of overcalling of CLL-specific methylation patterns in previous studies (~30-fold for protein-coding genes and ~10-fold for miRNAs) and stresses the importance to consider normal differentiation trajectories for the identification of aberrant DNA methylation events. Here we propose 11 protein-coding genes (e.g. DOK2, CLLU1) and 4 miRNAs (e.g. miR-486, miR-195) as being epigenetically deregulated in CLL. Our analytical approach provides a general framework for the identification of disease-specific epigenomic changes that should be applicable to other cancers in the future. Disclosures Küppers: the Takeda Advisory Board: Membership on an entity's Board of Directors or advisory committees. Stilgenbauer:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genzyme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer-Ingelheim: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmcyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Hoffmann La-Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Enhanced B-Cell Differentiation and Increased Production of Antibodies Targeting Surface Membrane Antigens in Patients with Chronic Graft-Versus-Host Disease

Blood ◽

10.1182/blood.v128.22.670.670 ◽

2016 ◽

Vol 128 (22) ◽

pp. 670-670

Author(s):

Kathy S. Wang ◽

Corey S. Cutler ◽

Sarah Nikiforow ◽

Vincent T. Ho ◽

John Koreth ◽

...

Keyword(s):

Cell Differentiation ◽

B Cells ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

High Dose ◽

B Cell Differentiation ◽

Advisory Committees ◽

High Dose Steroid ◽

Healthy Donors

The mechanisms of chronic graft-versus-host disease (cGVHD) are complex and involve multiple elements of the immune system. Previous studies have indicated that donor B cells and the antibodies they produce play an important role in the development of cGVHD. T cells that facilitate B-cell differentiation, such as T Follicular Helper cells (Tfh), were also shown to exhibit enhanced function in patients with cGVHD. IL-21, a cytokine produced by Tfh cells plays an important role in the B-cell differentiation process. Activation of IL-21R expressed on B cells promotes B-cell differentiation into plasmablasts and plasma cells. To examine the responsiveness of B cells to this Tfh cytokine and antibody production in the setting of cGVHD, we analyzed B cells from 107 patients after allogeneic HSCT: 31 with no cGVHD, 44 with persistent stable cGVHD, and 22 patients with cGVHD receiving high-dose steroid therapy. Samples were collected from 9 months on after transplant. We also analyzed samples from 32 healthy donors as controls. The total CD19+CD20+ B-cell numbers in patients with stable cGVHD were comparable to those of healthy donors and slightly higher than normal in patients without cGVHD, suggesting normal recovery of B cells in these patients by the time the samples were collected. In patients with cGVHD, the number of IL-21R expressing B cells (CD19+CD20+IL21R+) was significantly increased compared to patients without cGVHD (p=0.046) or healthy donors (p=0.0036). The number of plasmablasts (CD19+CD20-CD38Hi) in patients with cGVHD was also significantly higher than in healthy donors (p=0.0079). Plasmablasts levels were higher in patients with cGVHD compared to those without cGVHD, but this difference was not statistically significant (p=0.3702). High-dose steroid therapy reduced both the number of IL-21R positive B cells and the number of plasmablasts, but neither reduction was statistically significant. We also examined IL-21 levels in plasma using multiplex cytokine bead arrays. Levels of circulating IL-21 were significantly higher in patients with cGVHD compared with healthy donors or patients without cGVHD. Increased levels of IL-21 and increased numbers of IL-21R+ B cells suggest that both homeostatic stimulation and inherent B-cell susceptibility promote B-cell differentiation in patients with cGVHD. Previous studies have shown that male transplant patients who received sex-mismatched grafts developed significantly higher levels of anti-H-Y IgG antibodies and the development of H-Y antibodies is highly correlated with development of cGVHD. To examine the impact of the observed enhanced B-cell differentiation on production of allo- and autoantibodies, we developed a fluorescent-linked immuno-assay to detect antibodies capable of targeting cell-surface proteins. Membrane protein extracts were prepared from a human skin fibroblast cell line (Detroit 551) and coated onto 96-well plates. Plasma samples from the above cohort of patients and healthy donors were incubated on the plate, and IgG antibodies reactive with plate-bound antigens were detected with fluorescence-conjugated anti-human IgG. Compared with patients who did not develop cGVHD and healthy donors, patients who developed cGVHD showed significantly higher levels of IgG reactive against cell-surface antigens (cGVHD vs HD, p=0.0124; cGVHD vs no GVHD, p=0.0027). High-dose steroid therapy significantly reduced the level of these antibodies (cGVHD vs cGVHD-T, p=0.0009). We also examined the presence of these antibodies at various times following HSCT. While patients who did not develop cGVHD had persistently low levels of these antibodies over a 3-year period, patients who developed cGVHD during this time had persistently high levels of these antibodies. These results indicate that in patients who developed cGVHD after transplant, B-cell differentiation and the production of antibodies that target living cells were enhanced. These data further support a role for B cells and antibodies in the development of cGVHD. Further characterization of the specificity of these antibodies will enhance our understanding of the role played by donor B cells in the development of cGVHD and provide new potential targets for therapy. Disclosures Koreth: prometheus labs inc: Research Funding; kadmon corp: Membership on an entity's Board of Directors or advisory committees; takeda pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; amgen inc: Consultancy; LLS: Research Funding; millennium pharmaceuticals: Research Funding. Armand:Roche: Research Funding; Pfizer: Research Funding; Infinity Pharmaceuticals: Consultancy; Sequenta Inc: Research Funding; Merck: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding. Soiffer:GentiumSpA/Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Ritz:Kiadis: Membership on an entity's Board of Directors or advisory committees.

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Assessing the role of the T-box transcription factor Eomes in B cell differentiation during either Th1 or Th2 cell-biased responses

PLoS ONE ◽

10.1371/journal.pone.0208343 ◽

2018 ◽

Vol 13 (12) ◽

pp. e0208343 ◽

Cited By ~ 3

Author(s):

Lucy Cooper ◽

Lauren Hailes ◽

Amania Sheikh ◽

Colby Zaph ◽

Gabrielle T. Belz ◽

...

Keyword(s):

Transcription Factor ◽

Cell Differentiation ◽

B Cell ◽

B Cell Differentiation ◽

T Box ◽

Th2 Cell

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Prospects for Understanding the Role of Lymphoid Microenvironments in B Cell Differentiation In Vivo

Microenvironments in the Lymphoid System ◽

10.1007/978-1-4613-2463-8_1 ◽

1985 ◽

pp. 3-8

Author(s):

Eugene C. Butcher

Keyword(s):

Cell Differentiation ◽

B Cell ◽

B Cell Differentiation

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Impact of Interim FDG-PET (iPET) in the Outcomes of Patients with Aggressive B-Cell Lymphomas Receiving DA-EPOCH-R

Blood ◽

10.1182/blood-2019-122393 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2898-2898

Author(s):

Vania Phuoc ◽

Leidy Isenalumhe ◽

Hayder Saeed ◽

Celeste Bello ◽

Bijal Shah ◽

...

Keyword(s):

B Cell ◽

Board Of Directors ◽

Fdg Pet ◽

Research Funding ◽

Cell Lymphoma ◽

B Cell Lymphoma ◽

Advisory Committees ◽

End Of Treatment

Introduction: 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) remains the standard of care for baseline and end of treatment scans for aggressive non-Hodgkin lymphomas (NHLs). However, the role of interim FDG-PET remains not as well defined across aggressive NHLs, especially in the era of high-intensity chemoimmunotherapy. Interim FDG-PET (iPET) can serve as an early prognostic tool, and prior studies evaluating the utility of iPET-guided treatment strategies primarily focused on diffuse large B-cell lymphomas (DLBCL) and frontline R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). Classification criteria systems assessing response also differ between studies with no clear consensus between use of Deauville criteria (DC), International Harmonization Project (IHP), and the ΔSUVmax method. Methods: This study evaluates our institutional experience with iPET during treatment with DA-EPOCH ± R (dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin with or without Rituximab) in aggressive NHLs. We retrospectively evaluated 70 patients at Moffitt Cancer Center who started on DA-EPOCH ± R between 1/1/2014 to 12/31/2018 for aggressive NHLs. Response on interim and end-of-treatment (EOT) scans were graded per DC, IHP, and ΔSUVmax methods, and progression free survival (PFS) probability estimates were calculated with chi-square testing and Kaplan Meier method. PFS outcomes were compared between interim negative and positive scans based on each scoring method. Outcomes were also compared between groups based on interim versus EOT positive or negative scans. Results: We identified 70 patients with aggressive NHLs who received DA-EPOCH ± R at our institute. The most common diagnoses were DLBCL (61%) followed by Burkitt's lymphoma (10%), primary mediastinal B-cell lymphoma (9%), plasmablastic lymphoma (7%), gray zone lymphoma (6%), primary cutaneous large B-cell lymphoma (1%), primary effusion lymphoma (1%), and other high-grade NHL not otherwise specified (3%). Of the 43 patients with DLBCL, 21/43 (49%) had double hit lymphoma (DHL) while 7/43 (16%) had triple hit lymphoma (THL), and 3/43 (7%) had MYC-rearranged DLBCL while 2/43 (5%) had double expressor DLBCL. Thirty nine out of 70 (56%) were female, and median age at diagnosis was 58.39 years (range 22.99 - 86.86 years). Most patients had stage IV disease (49/70, 70%), and 43/70 (61%) had more than one extranodal site while 45/70 (64%) had IPI score ≥ 3. Forty-six out of 70 (66%) received central nervous system prophylaxis, most with intrathecal chemotherapy (44/70, 63%). Fifty-five out of 70 (79%) had iPET available while 6/70 (9%) had interim computerized tomography (CT) scans. Fifty-six out of 70 (80%) had EOT PET, and 4/70 (6%) had EOT CT scans. Sustained complete remission occurred in 46/70 (66%) after frontline DA-EPOCH ± R (CR1), and 12/70 (17%) were primary refractory while 5/70 (7%) had relapse after CR1. Four of 70 (6%) died before cycle 3, and 3/70 (4%) did not have long-term follow-up due to transition of care elsewhere. Median follow-up was 15.29 months (range 0.85 - 60.09 months). There was significantly better PFS observed if iPET showed DC 1-3 compared to DC 4-5 (Χ2=5.707, p=0.0169), and PFS was better if iPET was negative by IHP criteria (Χ2=4.254, p=0.0392) or ΔSUVmax method (Χ2=6.411, p=0.0113). Comparing iPET to EOT PET, there was significantly better PFS if iPET was negative with EOT PET negative (iPET-/EOT-) compared to iPET positive with EOT negative (iPET+/EOT-), and iPET+/EOT+ and iPET-/EOT+ had worse PFS after iPET-/EOT- and iPET+/EOT- respectively. This pattern in iPET/EOT PFS probability remained consistent when comparing DC (Χ2=30.041, p<0.0001), IHP (Χ2=49.078, p<0.0001), and ΔSUVmax method (Χ2=9.126, p=0.0104). These findings fit clinical expectations with positive EOT scans indicating primary refractory disease. There was no significant difference in PFS when comparing DLBCL versus non-DLBCL (Χ2=3.461, p=0.0628) or DHL/THL versus non-DHL/THL diagnoses (Χ2=2.850, p=0.0914). Conclusion: Our findings indicate a prognostic role of iPET during treatment with DA-EPOCH ± R for aggressive NHLs. Significant differences in PFS were seen when graded by DC, IHP, and ΔSUVmax methods used in prior studies and when comparing interim versus EOT response. Larger studies are needed to confirm these findings. Disclosures Bello: Celgene: Speakers Bureau. Shah:Novartis: Honoraria; AstraZeneca: Honoraria; Spectrum/Astrotech: Honoraria; Adaptive Biotechnologies: Honoraria; Pharmacyclics: Honoraria; Jazz Pharmaceuticals: Research Funding; Incyte: Research Funding; Kite/Gilead: Honoraria; Celgene/Juno: Honoraria. Sokol:EUSA: Consultancy. Chavez:Janssen Pharmaceuticals, Inc.: Speakers Bureau; Genentech: Speakers Bureau; Kite Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees.

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IFI16Expression Is Related to Selected Transcription Factors during B-Cell Differentiation

Journal of Immunology Research ◽

10.1155/2015/747645 ◽

2015 ◽

Vol 2015 ◽

pp. 1-20 ◽

Cited By ~ 6

Author(s):

Pier Paolo Piccaluga ◽

Claudio Agostinelli ◽

Fabio Fuligni ◽

Simona Righi ◽

Claudio Tripodo ◽

...

Keyword(s):

Transcription Factors ◽

Cell Differentiation ◽

B Cell ◽

Peripheral Blood Lymphocytes ◽

B Cell Differentiation ◽

Cellular Survival ◽

Human B Cells ◽

Proliferation And Differentiation ◽

B Cell Subsets

The interferon-inducible DNA sensor IFI16 is involved in the modulation of cellular survival, proliferation, and differentiation. In the hematopoietic system, IFI16 is consistently expressed in the CD34+ stem cells and in peripheral blood lymphocytes; however, little is known regarding its regulation during maturation of B- and T-cells. We explored the role of IFI16 in normal B-cell subsets by analysing its expression and relationship with the major transcription factors involved in germinal center (GC) development and plasma-cell (PC) maturation.IFI16mRNA was differentially expressed in B-cell subsets with significant decrease inIFI16mRNA in GC and PCs with respect to naïve and memory subsets.IFI16mRNA expression is inversely correlated with a few master regulators of B-cell differentiation such asBCL6, XBP1, POU2AF1, andBLIMP1. In contrast,IFI16expression positively correlated withSTAT3, REL, SPIB, RELA, RELB, IRF4, STAT5B, andSTAT5A. ARACNE algorithm indicated a direct regulation ofIFI16byBCL6,STAT5B, andRELB, whereas the relationship betweenIFI16and the other factors is modulated by intermediate factors. In addition, analysis of the CD40 signaling pathway showed thatIFI16gene expression directly correlated with NF-κB activation, indicating that IFI16 could be considered an upstream modulator of NF-κB in human B-cells.

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THU0243 ROLE OF METHIONINE AND ITS TRANSPORTER CD98 IN HUMAN B CELL DIFFERENTIATION AND THE RELEVANCE TO PATHOLOGICAL PROCESSES OF SLE

10.1136/annrheumdis-2019-eular.4452 ◽

2019 ◽

Author(s):

Mingzeng Zhang ◽

Shigeru Iwata ◽

Maiko Hajime ◽

Naoaki Ohkubo ◽

Yasuyuki Todoroki ◽

...

Keyword(s):

Cell Differentiation ◽

B Cell ◽

B Cell Differentiation ◽

Human B Cell

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A Critical Role of Blockade of Cell Differentiation in BCR-ABL-Induced B-Cell Acute Lymphoblastic Leukemia (B-ALL): Basis for Superb Therapeutic Effect on B-ALL in Mice by Promotion of Pro-B Leukemic Cell Differentiation and Treatment with Imatinib.

Blood ◽

10.1182/blood.v106.11.844.844 ◽

2005 ◽

Vol 106 (11) ◽

pp. 844-844

Author(s):

Yiguo Hu ◽

Linghong Kong ◽

Kevin Staples ◽

Kevin Mills ◽

John G. Monroe ◽

...

Keyword(s):

Cell Differentiation ◽

Acute Lymphoblastic Leukemia ◽

B Cell ◽

Myeloid Leukemia ◽

Lymphoblastic Leukemia ◽

Leukemic Cell ◽

Leukemic Cells ◽

B Cell Differentiation ◽

Cell Acute Lymphoblastic Leukemia

Abstract The BCR-ABL oncogene induces human Philadelphia-positive (Ph+) B-cell acute lymphoblastic leukemia (B-ALL) and chronic myeloid leukemia (CML) that advances to acute phase of CML called blast crisis. In this acute phase, CML patients can develop either B-ALL or acute myeloid leukemia. In B-ALL, differentiation of leukemic cells are blocked at pro-/pre-B stage, and the underlying mechanism is unknown. We hypothesize that this blockade of B-cell differentiation may be important for the development of B-ALL induced by BCR-ABL, and if so, promotion of B-leukemic cell differentiation would create a novel therapeutic strategy for B-ALL. To test this hypothesis, we first compared the percentages of IgM+ B-leukemic cells in BALB/c and C57BL/6 (B6) mice with BCR-ABL-induced B-ALL, because we have previously found that B-ALL develops more quickly in BALB/c mice than in B6 mice (Li et al, J. Exp. Med.189:1399–1412, 1999). We expressed BCR-ABL in bone marrow (BM) using retroviral transduction and transplantation in these two different strains of inbred mice to induce B-ALL. There were significantly more peripheral blood B220+ B cells in BALB/c B-ALL mice than those in B6 mice, correlating to faster B-ALL in BALB/c mice than in B6 mice. Among these B220+ cells, IgM+ cells were much less in BALB/c mice than in B6 mice. We also compared rearrangement of the B cell antigen receptor (BCR) heavy chains (m chains) between BALB/c and B6 backgrounds using BCR-ABL-expressing pro-B cell lines isolated from the B-ALL mice. Normal m chains rearrangement was found in B6 leukemic cells, but not in BALB/c leukemic cells. These results indicate that more differentiated B-leukemic cells are associated with less aggressive disease. To further demonstrate the role of blockade of B-cell differentiation in B-ALL development, we induced B-leukemic cell differentiation by co-expression of BCR-ABL and intact immunoregulatory tyrosine activation motifs (ITAM) contained in immunoglobulin (Ig)_/Igß complexes in BM cells of B-ALL mice, comparing to expression of BCR-ABL alone. We treated these mice with imatinib (orally, 100 mg/kg, twice a day). The treated mice with B-ALL induced by co-expression of BCR-ABL and ITAM lived three-week longer than those with B-ALL induced by BCR-ABL only, with some mice in long-term remission. Prolonged survival was associated with 50% increased B220+/IgM+ B-leukemic cells in peripheral blood of the mice. Taken together, our results demonstrate that blockade of B-cell differentiation is critical for the development of B-ALL induced by BCR-ABL, and provide a rationale for combination therapy of B-ALL with imatinib and induction of leukemic cell differentiation.

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