Constitutively Activated STAT3 Promotes Cell Proliferation and Survival in the Activated B Cell Subtype of Diffuse Large B Cell Lymphomas.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1621-1621
Author(s):  
Bihui Hilda Ye ◽  
Beibei Belinda Ding ◽  
Jian Jessica Yu ◽  
Raymond Y.-L. Yu ◽  
Lourdes M. Mendez ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
B Cell Lymphoma ◽  
Cell Development ◽  
B Cell Development ◽  
Reciprocal Relationship ◽  
B Cell Lymphomas ◽  
Large B Cell

Abstract During B cell development, cell proliferation and survival are regulated by stage-specific transcription factors. Accordingly, distinct oncogenic pathways are employed by B cell lymphomas representing different stages of B cell development. Diffuse large B cell lymphoma (DLBCL) contains at least two main phenotypic subtypes, i.e. the germinal center B cell-like (GCB-DLBCL) and the activated B cell-like (ABC-DLBCL) groups. It has been shown that GCB-DLBCL responds favorably to chemotherapy and expresses high levels of BCL6, a transcription repressor known to play a causative role in lymphomagenesis. In comparison, ABC-DLBCL has lower levels of BCL6, constitutively activated NF-kappaB and tends to be refractory to chemotherapy. In this study, we investigated the relationship between BCL6 and STAT3 expression/activation in DLBCL and normal GC B cells. Our results demonstrate that BCL6 directly inhibits transcription of the STAT3 gene by binding to two BCL6 sites in its 5′ regulatory region. As a result, high level STAT3 expression and activation are preferentially detected in ABC-DLBCL and BCL6-negative normal germinal center B cells. Specifically, in tonsillar GCs, STAT3 expression and activation is restricted to a previously uncharacterized subset of BCL6−Blimp-1− B cells in the apical light zone. The location and phenotype of these cells suggest that they are in the process of exiting the BCL6-directed GC program and transitioning to a plasma cell differentiation process governed by Blimp-1. The reciprocal relationship between BCL6 and STAT3 is also conserved in DLBCL such that STAT3 expression and activation is preferentially associated with the BCL6-low, ABC subtype. Most importantly, inactivating STAT3 by either AG490 or small interference RNA in ABC-DLBCL cells inhibits cell proliferation and triggers apoptosis. These phenotypes are accompanied by decreased expression of several known STAT3 target genes, including c-Myc, JunB and Mcl-1, and increased expression of the cell cycle inhibitor p27. In addition to identifying STAT3 as a novel BCL6 target gene, our results define STAT3 activation as a second oncogenic pathway operating in ABC-DLBCL and suggest that blocking STAT3 may be potentially therapeutic in treatment of these aggressive lymphomas.

scholarly journals Harnessing lymphoma epigenetics to improve therapies

Blood ◽  
2020 ◽  
Vol 136 (21) ◽  
pp. 2386-2391
Author(s):  
Haopeng Yang ◽  
Michael R. Green
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Genetic Alterations ◽  
Cell Development ◽  
B Cell Development ◽  
Affinity Maturation

Abstract Affinity maturation and terminal differentiation of B cells via the germinal center reaction is a complex multistep process controlled by transcription factors that induce or suppress large dynamic transcriptional programs. This occurs via the recruitment of coactivator or corepressor complexes that epigenetically regulate gene expression by post-translationally modifying histones and/or remodeling chromatin structure. B-cell–intrinsic developmental programs both regulate and respond to interactions with other cells in the germinal center that provide survival and differentiation signals, such as T-follicular helper cells and follicular dendritic cells. Epigenetic and transcriptional programs that naturally occur during B-cell development are hijacked in B-cell lymphoma by genetic alterations that directly or indirectly change the function of transcription factors and/or chromatin-modifying genes. These in turn skew differentiation toward the tumor cell of origin and alter interactions between lymphoma B cells and other cells within the microenvironment. Understanding the mechanisms by which genetic alterations perturb epigenetic and transcriptional programs regulating B-cell development and immune interactions may identify opportunities to target these programs using epigenetic-modifying agents. Here, we discuss recently published studies centered on follicular lymphoma and diffuse large B-cell lymphoma within the context of prior knowledge, and we highlight how these insights have informed potential avenues for rational therapeutic interventions.

scholarly journals Harnessing lymphoma epigenetics to improve therapies (article not eligible for CME credit)

Hematology ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 95-100
Author(s):  
Haopeng Yang ◽  
Michael R. Green
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Genetic Alterations ◽  
Cell Development ◽  
B Cell Development ◽  
Affinity Maturation

Abstract Affinity maturation and terminal differentiation of B cells via the germinal center reaction is a complex multistep process controlled by transcription factors that induce or suppress large dynamic transcriptional programs. This occurs via the recruitment of coactivator or corepressor complexes that epigenetically regulate gene expression by post-translationally modifying histones and/or remodeling chromatin structure. B-cell–intrinsic developmental programs both regulate and respond to interactions with other cells in the germinal center that provide survival and differentiation signals, such as T-follicular helper cells and follicular dendritic cells. Epigenetic and transcriptional programs that naturally occur during B-cell development are hijacked in B-cell lymphoma by genetic alterations that directly or indirectly change the function of transcription factors and/or chromatin-modifying genes. These in turn skew differentiation toward the tumor cell of origin and alter interactions between lymphoma B cells and other cells within the microenvironment. Understanding the mechanisms by which genetic alterations perturb epigenetic and transcriptional programs regulating B-cell development and immune interactions may identify opportunities to target these programs using epigenetic-modifying agents. Here, we discuss recently published studies centered on follicular lymphoma and diffuse large B-cell lymphoma within the context of prior knowledge, and we highlight how these insights have informed potential avenues for rational therapeutic interventions.

scholarly journals Transcription factors of the alternative NF-κB pathway are required for germinal center B-cell development

2016 ◽  
Vol 113 (32) ◽  
pp. 9063-9068 ◽  
Author(s):  
Nilushi S. De Silva ◽  
Michael M. Anderson ◽  
Amanda Carette ◽  
Kathryn Silva ◽  
Nicole Heise ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Alternative Pathway ◽  
Cell Development ◽  
B Cell Development ◽  
Cell Surface Receptor ◽  
Signaling Cascade

The NF-κB signaling cascade relays external signals essential for B-cell growth and survival. This cascade is frequently hijacked by cancers that arise from the malignant transformation of germinal center (GC) B cells, underscoring the importance of deciphering the function of NF-κB in these cells. The NF-κB signaling cascade is comprised of two branches, the canonical and alternative NF-κB pathways, mediated by distinct transcription factors. The expression and function of the transcription factors of the alternative pathway, RELB and NF-κB2, in late B-cell development is incompletely understood. Using conditional deletion of relb and nfkb2 in GC B cells, we here report that ablation of both RELB and NF-κB2, but not of the single transcription factors, resulted in the collapse of established GCs. RELB/NF-κB2 deficiency in GC B cells was associated with impaired cell-cycle entry and reduced expression of the cell-surface receptor inducible T-cell costimulator ligand that promotes optimal interactions between B and T cells. Analysis of human tonsillar tissue revealed that plasma cells and their precursors in the GC expressed high levels of NF-κB2 relative to surrounding lymphocytes. Accordingly, deletion of nfkb2 in murine GC B cells resulted in a dramatic reduction of antigen-specific antibody-secreting cells, whereas deletion of relb had no effect. These results demonstrate that the transcription factors of the alternative NF-κB pathway control distinct stages of late B-cell development, which may have implications for B-cell malignancies that aberrantly activate this pathway.

scholarly journals CtIP is essential for early B cell proliferation and development in mice

2019 ◽  
Vol 216 (7) ◽  
pp. 1648-1663 ◽  
Author(s):  
Xiangyu Liu ◽  
Xiaobin S. Wang ◽  
Brian J. Lee ◽  
Foon K. Wu-Baer ◽  
Xiaohui Lin ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
B Cells ◽  
B Cell ◽  
Essential Gene ◽  
Nuclease Activity ◽  
Cell Development ◽  
Nuclear Body ◽  
B Cell Development ◽  
Immunoglobulin Gene ◽  
End Resection

B cell development requires efficient proliferation and successful assembly and modifications of the immunoglobulin gene products. CtIP is an essential gene implicated in end resection and DNA repair. Here, we show that CtIP is essential for early B cell development but dispensable in naive B cells. CtIP loss is well tolerated in G1-arrested B cells and during V(D)J recombination, but in proliferating B cells, CtIP loss leads to a progressive cell death characterized by ATM hyperactivation, G2/M arrest, genomic instability, and 53BP1 nuclear body formation, indicating that the essential role of CtIP during proliferation underscores its stage-specific requirement in B cells. B cell proliferation requires phosphorylation of CtIP at T847 presumably by CDK, but not its interaction with CtBP or Rb or its nuclease activity. CtIP phosphorylation by ATM/ATR at T859 (T855 in mice) promotes end resection in G1-arrested cells but is dispensable for B cell development and class switch recombination, suggesting distinct roles for T859 and T847 phosphorylation in B cell development.

The Loss of Kdm6a in B-Cell Development Causes Germinal Center Hyperplasia and Impedes the B-Cell Immune Response in a Specific Manner

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 5-5
Author(s):  
Ling Tian ◽  
Monique Chavez ◽  
Lukas D Wartman
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Cell Development ◽  
Young Female ◽  
B Cell Development ◽  
Cell Immune Response ◽  
Germinal Center Hyperplasia

Putative loss-of-function mutations in KDM6A, an X-linked H3K27 demethylase, occur recurrently in B-cell malignancies, including B-cell non-Hodgkin lymphoma. How the KDM6A in normal B cell development and function, as well as the mechanism(s) by which its loss contributes lymphomagenesis has not been defined. To address this issue, we generated a conditional knockout mouse of the Kdm6a gene (with LoxP sites flanking the 3rd exon) and crossed these mice with Vav1-Cre transgenic mice to selectively inactivate Kdm6a in hematopoietic stem/progenitor cells. Our previous data have shown young Kdm6a-null mice have a myeloid skewing in the bone marrow, spleen and peripheral blood. These changes became more pronounced with age and were specific to the female, homozygous Kdm6a knockout mice. Early B-cell development is also altered in female Kdm6a-null mice. Flow cytometry showed a decrease in multipotent progenitor cells (MPPs) with a decrease in both common lymphoid progenitors (CLPs) and B cell-biased lymphoid progenitors (BLPs) in young, female Kdm6a-null mice bone marrow. B-cell progenitor analysis (Hardy profiles) showed an increase in Fraction A with a concomitant decrease in Fraction B/C and Fraction D. The GC B-cells are thought to be the cell-of-origin of diffuse large B-cell lymphoma (DLBCL). To determine if the loss of Kmd6a could impact the mature B cells undergo germinal center (GC) reaction, we immunized the young, female Kdm6a-null mcie and wildtype littermates with T cell-dependent antigen sheep red blood cell (SRBC). Mice were scrificed 14 days after immunization, spleen cells were examined by flow cytometry. As expected, we observed a significant increase in the percentage of GC B cells (B220+GL7+CD95+) from female Kdm6a-null mice compared to control mice. We also observed differences in the percentage of other B-cell subsets between these mice, including an increase in plasma cells (B220-CD138+) and memory B cells (B220+CD19+CD27+), concomitant with an increase trend towards the elevated marginal zone B cells (B220+CD23loCD21+) and transitional B cells (B220+CD23-CD21-). In contrast, there was a decrease in the follicular zone B cells (B220+CD23-CD21-) and plasmablast (B220+CD138+). To analyze the levels of SRBC-specific Abs from immunized mice, serum was collected from blood at day 14. A flow cytometry-based assay was performed to detect the fluorescent-labeled SRBC-specfic Abs for immunoglobulin. Results showed that the abundance of non-class-switched anti-SRBC IgM level was significantly increased in female Kdm6a-null mice serum compared with control mice. In contrast, these mice had significantly decreased anti-SRBC IgA, IgG, IgG1, IgG3 and IgE levels indicating a isotype class switch defect. The aberrant GC phenotype induced by SRBC indeicated that kdm6a loss results in expansion of GC B cells, which subsequently enhances the plasma cell generation. This finding prompted us to investigate if the Kdm6a impairs the immunoglobulin affinity maturation. Therefore, we analyzed the ability of female Kdm6a-null mice and wildtype littermates to generate specific Abs against another T cell-dependent antigen NP-Chicken Gamma Globulin (NP-CGG). Mice were immunized with NP-CGG (29) and serum were collected weekly up to 8 weeks total. ELISA analysis of serum revealed that NP-specfic total Ig level were similar for both groups of mice over time. However, consistent with the SRBC immunization results, we did observed a sinificant reduction in the titers of NP-specific IgA and IgG1 Abs in female Kdm6a-null mice compared with control mice at each time point, while these mice had a sinificant increase in NP-specific IgM Abs, which indicating the loss of Kdm6a disrupts the balance between non-class-switched and class-switched NP-specific Abs isotypes (Figure 1A-D). Likewise, we also observed an increase in the percentage of GC B cells and plasma cells 8 weeks after NP-CGG immunization by flow cytometry. Again, our findings indicate the loss of Kdm6a causes germinal center hyperplasia, enhances plasma cell differentiation, and likely impairs class switch recombination (CSR). Taken together, our data shows that Kdm6a plays an important, but complex, role in B-cell transiting in the GC reaction and that loss of Kdm6a causes germinal center hyperplasia and impedes the B-cell immune response in a specific manner that may contribute to infection and B-cell malignancies. Disclosures Wartman: Novartis: Consultancy; Incyte: Consultancy.

Preferential Acquision of N-Glycosylation Sites in the VDJ Region in Germinal Center B-Cell-Like Difusse Large B-Cell Lymphoma

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1589-1589 ◽  
Author(s):  
Miguel Alcoceba ◽  
Elena Sebastián ◽  
Ana Balanzategui ◽  
Luis Marín ◽  
Santiago Montes-Moreno ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Marginal Zone ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Marginal Zone Lymphoma ◽  
Large B Cell Lymphoma ◽  
Glycosylation Sites ◽  
Large B Cell

Abstract Abstract 1589 Introduction: Acquired potentially N-glycosylation sites are produced by somatic hypermutation (SHM) in the immunoglobulin (Ig) variable region. This phenomenon is produced in ∼9% of normal B-cells and seems to be related to certain B-cell lymphoproliferative disorders (B-LPDs) such as follicular lymphoma (FL, 79%), endemic Burkitt lymphoma (BL, 82%) and diffuse large B-cell lymphoma (DLBCL, 41%). These data suggest that new potential N-glycosylation sites could be related to germinal center B (GCB)-LPDs. By contrast, in other B-LPDs, such as chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), MALT lymphoma, Waldenström macroglobulinemia (WM) or multiple myeloma (MM), these modifications have not been analyzed in deep. Aims: To evaluate the acquisition of potential N-glycosylation sites in B-LPDs, including immunohystochemical DLBCL subtypes (GCB and non-GCB) and specific non-GCB-LPDs, such as hairy cell leukemia (HCL), splenic marginal-zone lymphoma (SMZL), CLL, MCL, ocular extranodal marginal zone lymphoma (OAEMZL), MM and WM. Patients: A total of 953 sequences (203 from our group and 750 previously published sequences) of B-LPDs were included. Diagnosis distribution was as follows: DLBCL (n=235), MCL (n=235), CLL (n=166), MM (n=96), OAEMZL (n=82), SMZL (n=68), WM (n=38) and HCL (n=33). Methods: Acquired N-glycosylation sites were counted according to the sequence Asn-X-Ser/Thr, where X could be any amino acid except Pro. Natural motifs in germline sequences of IGHV1–08, IGHV4–34 e IGHV-5a were not considered. Fisher test was used to perform comparisons between groups. To distinguish DLBCL biological subtypes (GCB and non-GCB DLBCL), Hans' algorithm was used. Results: A total of 83 out of the 235 DLBCL cases acquired at least a new N-glycosylation site, a higher value than in normal B-cells (35% vs. 9%, p<0.0001). Higher incidence of these motifs in the group of GCB as compared to non-GCB DLBCL were observed (52% vs. 20%, p<0.0001). Those cases diagnosed of HCL, CLL, MCL, MM, WM, OAEMZL and SMZL presented a reduced number of new N-glycosylation sites, showing similar values than normal B-cells (range 3–18%, p=ns). Conclusions: We described for the first time the pattern of N-glycosylation in HCL, SMZL, OAEMZL and in the immunohystochemical DLBCL subtypes, where the GCB-DLBCL showed a higher number of new N-glycosylation sites with respect to non-GCB DLBCL and other non-GCB-LPDs. The presence of novel N-glycosylation sites in FL, BL and in GCB-DLBCL strongly suggests that these motifs are characteristic of the germinal center B-LPDs. Disclosures: No relevant conflicts of interest to declare.

Profiles Of De Novo CD25-Positive Mature B-Cell Lymphomas

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4308-4308
Author(s):  
Shin-ichiro Fujiwara ◽  
Raine Tatara ◽  
Kiyoshi Okazuka ◽  
Iekuni Oh ◽  
Ken Ohmine ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
High Expression ◽  
B Cell Lymphomas ◽  
Cns Involvement ◽  
Cd25 Expression

Abstract Background Interleukin 2 (IL-2) is an important cytokine that controls the proliferation and differentiation of not only T- but also B-lymphocytes. Recently, we reported that CD25 (IL-2 receptor alpha chain, IL-2R) is expressed in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL), and high expression of CD25 in the two types of lymphoma is correlated with a poor prognosis following chemotherapy regimens containing rituximab (ASH annual meeting, 2011 118:2666, 2012 120:1543). We evaluated the clinical significance of CD25 expression in a larger series of different mature B-cell lymphomas (BCL). Patients and Methods Four hundred and thirty-seven newly diagnosed patients who were admitted to our hospital between 2002 and 2013 were retrospectively evaluated. Lymph node or related tissue biopsy samples of BCL were analyzed using flow cytometry, as follows: 182 patients, DLBCL; 92, FL; 48, chronic lymphocytic leukemia (CLL); 21, mantle cell lymphoma (MCL); 23, marginal zone lymphoma (MZL); 8, Burkitt lymphoma (BL); 18, B-cell lymphoma unclassifiable with features intermediate between BL and DLBCL (BL/DLBCL); 5, lymphoplasmacytic lymphoma (LPL); and 39, reactive lymphadenopathy with sufficient B-cells. CD25-positivity was defined as >20% of clonal B-cells in a gated region. Results CD25 expression in patients with MCL, CLL, MZL, and DLBCL was significantly higher than that in patients with reactive lymphadenopathy (P<0.001,<0.001, =0.019, and <0.001, respectively). BL and FL, which were derived from germinal center B-cells, did not express CD25. These results indicate that pre- or post- germinal center-derived B-cells, activated by IL-2/IL-2R signaling, may give rise to CD25+ BCL such as CD25+ MCL, CLL, MZL, and DLBCL. The highest median CD25 expression (41.5%) was observed in MCL. CD25 expression was higher in MCL than CD5+ BCL (CLL and CD5+ DLBCL) (median, 41.5 vs. 16.9%, respectively; P<0.001). With a cut-off value of 60% CD25-positivity, patients with CD25-high (>60%) MCL (n=9) were not treated with aggressive chemotherapy regimens such as Hyper-CVAD due to their age and characteristics, compared with those with CD25-low (<60%) MCL (n=12) (11.1 vs. 72.7%, respectively, P=0.021). In patients with CLL, the range of CD25 expression was wide (0.4-90.7%), and 29 patients (60%) showed CD25-positivity (CD25+ CLL). CD25+ CLL showed higher soluble IL-2R (sIL-2R) levels and an inferior overall survival (OS) than CD25- CLL (median sIL-2R, 2,195 vs. 706 U/ml P=0.047; 5-year OS, 62.7 vs. 100%; P=0.037). There was a significant correlation between levels of CD25 and sIL-2R (r=0.53, P=0.0053). It is clinically important to distinguish between DLBCL and BCL involving MYC oncogene rearrangement (BL and BL/DLBCL, MYC+ BCL). The former showed higher CD25 expression than the latter (median, 10.2 vs. 2.1%, respectively, P=0.04). The progression-free survival rate (PFS) after rituximab containing chemotherapy was inferior in patients with CD25+ DLBCL (n=72) than those with CD25- DLBCL (n=110) and MYC+ BCL (5-year PFS, 49 vs. 70.4, 66.3%, respectively). In patients with DLBCL, central nerve system (CNS) involvement was observed in 15 patients (7 at diagnosis and 8 at relapse). CD25+ DLBCL showed a higher frequency of CNS involvement than CD25– DLBCL (13.8 vs. 4.5%, respectively, P=0.049). Regarding MZL, CD25 was highly expressed in nodal MZL, but it showed a low expression in splenic MZL. Regarding the sites of extranodal MZL, CD25 expression was lower in the thyroid than at other sites (median, 5.1 vs. 21.2%, respectively, P=0.37). There were some differences between CD25+ (n=9) and CD25- (n=14) MZL concerning the presence of B symptoms (33.3 vs. 0%, respectively) and advanced stage (66.6 vs. 35.7%, respectively). Conclusion CD25 expression using flow cytometry can potentially provide diagnostic and prognostic implications on BCL patient. The high expression of CD25 in MCL and CLL suggests the possibility of targeted anti-CD25 immunotherapy. These findings may shed light on the role of CD25 expression in B-cell lymphomagenesis. Disclosures: No relevant conflicts of interest to declare.

Overexpression of BCL-2 Does Not Inhibit Autophagy in Human Follicular and Diffuse Large B-Cell Lymphomas

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3007-3007
Author(s):  
Aine McCarthy ◽  
Andrew James Clear ◽  
Jacek Marzec ◽  
Rita Coutinho ◽  
Robert D. Petty ◽  
...  
Keyword(s):  
B Cells ◽  
Protein Expression ◽  
B Cell ◽  
Prognostic Significance ◽  
B Cell Lymphoma ◽  
Beclin 1 ◽  
Pcr Array ◽  
B Cell Lymphomas ◽  
Autophagy Activity ◽  
Large B Cell

Abstract Background: Human follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) are the most common forms of indolent and aggressive NHL, respectively. The t(14;18) translocation characterizes approximately 85% of FL and 20% of DLBCL and results in constitutive overexpression of the anti-apoptotic protein BCL-2. It was previously reported that BCL-2 plays dual roles in preventing apoptosis and autophagy. Autophagy is a physical and pathological process whereby cells sequester portions of cytoplasm including organelles to form autophagosomes where they are degraded and recycled. Growing evidence demonstrates that autophagy plays important roles in tumorigenesis, tumor progression, and resistance to chemotherapy. Aims: The autophagy status in human B-cell lymphomas is unknown. We hypothesized that overexpression of BCL-2 could change autophagy status and aimed to determined expression of autophagy-related genes and proteins in FL and DLBCL primary samples by PCR array and tissue microarray. We aimed to evaluate whether expression of the autophagy-related proteins p62, Beclin-1 and LC3 individually and in combination with BCL-2 protein expression could risk-stratify FL and DLBCL patients at diagnosis. Patients and methods: Using PCR array, the autophagy-related gene expression profiles were determined in purified and unpurified reactive and malignant human lymph node tissue biopsies. Diagnostic tissues from FL (n=117) and DLBCL (n=109) patients were microarrayed and autophagy protein expression was evaluated using immunohistochemistry. Univariate and multivariate analyses on both continuous and categorical variables were conducted to measure overall survival (OS), disease specific survival (DSS), and progression-free survival (PFS). Results: Seven autophagy machinery genes were up-regulated in purified FL B-cells, namely ATG9A, ATG16L1, MAP1LC3A, GABARAPL1, ULK1, LAMP1 and HDAC6 compared with reactive B-cells. Two autophagy machinery genes, MAP1LC3A and DRAM1, were up-regulated in DLBCL B-cells. In unpurified tissue biopsies, 20 of 46 genes in FL and 2 of 5 genes in DLBCL with increased expression were autophagy machinery genes. CTSD (cathepsin D) and TGM2 (transglutaminase 2) genes and proteins were mainly up-regulated in DLBCL tumor-infiltrating macrophages. These results demonstrate that FL and DLBCL showed increased expression of autophagy-related genes, regardless of the heterogeneity of these diseases. p62, a selective autophagy substrate; LC3, an autophagosome membrane protein; and Beclin-1, an essential autophagy effector, are often used to evaluate autophagy activity in the cell. 91% FL samples were BCL-2 positive but significantly decreased expression of p62, LC3 and Beclin-1 in FL samples was observed in both intra-follicular and non-malignant inter-follicular areas. This suggests that increased basal autophagy activity in both malignant FL cells and surrounding tumor infiltrating cells, indicating that BCL-2 does not inhibit basal autophagy activity. DLBCL samples displayed heterogeneous expression patterns of BCL-2, p62, LC3 and Beclin-1. We found that decreased p62 expression confers worse OS (continuous P=0.015; and categorical P=0.003), DSS (continuous P=0.037; categorical P=0.014) and PFS (categorical P=0.002) in DLBCL patients. Decreased expression of Beclin-1 was also confers poor prognosis in both FL and DLBCL as conducted by categorical analysis, OS (DLBCL, P=0.015; FL, P=0.004), DSS (FL, P=0.006), and PFS (DLBCL, P=0.029). p62 retains prognostic significance after adjustment for the International Prognostic Index (IPI) score and levels of BCL-2, Beclin-1 and LC3 in multivariate analysis. Beclin-1 retains its prognostic significance in FL after adjusting for FLIPI scores. Low p62 plus high BCL-2 expression in DLBCL confers the worst OS (P<0.0001) and DSS (P=0.001) compared with other combinations. Conclusions: These results demonstrate that FL has increased basal autophagy activity, while it varies in DLBCL. p62 is a novel, independent prognostic biomarker for DLBCL but not for FL. Combining p62 with BCL-2 provides a more robust and reliable method to risk-stratify DLBCL patients at diagnosis. Importantly, we report for the first time that overexpression of BCL-2 in human NHL does not inhibit basal autophagy activity. We propose that increased autophagy activity could be a therapeutic target for treatment of NHL. Disclosures Gribben: Celgene: Research Funding; Pharmacyclics: Honoraria; Roche: Honoraria.

scholarly journals Two Distinct Pathways of B-Cell Development in Peyer’s Patches

1995 ◽  
Vol 4 (4) ◽  
pp. 263-277 ◽  
Author(s):  
Philip J. Griebel ◽  
Birgit Kugelberg ◽  
Giorgio Ferrari
Keyword(s):  
Cell Proliferation ◽  
B Cells ◽  
B Cell ◽  
Lymphoid Tissue ◽  
Day Treatment ◽  
Cell Development ◽  
B Cell Development ◽  
Peyer's Patches ◽  
Peyer’S Patches ◽  
Dexamethasone Treatment

The developmental biology of sheep ileal and jejunal Peyer’s patches (PP) was investigated using corticosteroids to deplete immature B lymphocytes. During a 7-day treatment with dexamethasone, ileal PP follicular (iPf)B-cell proliferation was arrested and most iPfB-cells died. This resulted in follicular involution with the survival of mesenchymal cells. No iPfB-cell proliferation was detected in follicular remnants for 4 weeks postdexamethasone treatment, and during a subsequent 3-month period, there was limited iPfB-cell proliferation that resulted in a partial regeneration of follicles. Ileal PP involution was also associated with a severe B lymphopenia that persisted for over 14 weeks and was characterized by the survival of primarily isotype-switched and CD5+sIgM+B-cells in blood. In contrast, the size of jejunal PP follicles was reduced following dexamethasone treatment, but intrafollicular B-cell proliferation was not arrested. Furthermore, within 4 weeks, the jejunal PP follicles had recovered in size and cellularity and there was no disruption in IgA plasma-cell production. Thus, dexamethasone selectively depleted iPfB-cells and revealed that the ileal and jejunal PPs contain functionally distinct B-cell populations. The partial regeneration of the iPfB-cell population indicated that either an intrafollicular, corticosteroid-resistant B-stem cell existed or that ileal PP follicles can be repopulated by circulating B-cells. Finally, the association between ileal PP involution and the absence of circulating, CD5-B-cells confirmed that this lymphoid tissue provides an essential environment for conventional sIgM+B-cell development.

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