BCL6

Gene Summary

Gene:BCL6; B-cell CLL/lymphoma 6
Aliases: BCL5, LAZ3, BCL6A, ZNF51, ZBTB27
Location:3q27
Summary:The protein encoded by this gene is a zinc finger transcription factor and contains an N-terminal POZ domain. This protein acts as a sequence-specific repressor of transcription, and has been shown to modulate the transcription of START-dependent IL-4 responses of B cells. This protein can interact with a variety of POZ-containing proteins that function as transcription corepressors. This gene is found to be frequently translocated and hypermutated in diffuse large-cell lymphoma (DLCL), and may be involved in the pathogenesis of DLCL. Alternatively spliced transcript variants encoding different protein isoforms have been found for this gene. [provided by RefSeq, Sep 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:B-cell lymphoma 6 protein
HPRD
Source:NCBIAccessed: 28 February, 2015

Ontology:

What does this gene/protein do?
Show (42)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 28 February 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Chromosome 3
  • BCL6
  • Single Nucleotide Polymorphism
  • T-Lymphocytes
  • Repressor Proteins
  • Vitreous Body
  • BCL2
  • Karyotyping
  • Leukaemia
  • FISH
  • Chromosome 14
  • Risk Assessment
  • Risk Factors
  • DNA-Binding Proteins
  • Gene Expression Profiling
  • Neoplasm Proteins
  • Proto-Oncogene Proteins
  • B-Cell Lymphoma
  • Mutation
  • Gene Rearrangement
  • Immunophenotyping
  • Adolescents
  • Receptor Protein-Tyrosine Kinases
  • MicroRNAs
  • Immunoglobulin Heavy Chains
  • Germinal Center
  • Messenger RNA
  • Interferon Regulatory Factors
  • Non-Hodgkin Lymphoma
  • Nuclear Receptor Co-Repressor 2
  • Methotrexate
  • Follicular Lymphoma
  • Vascular Neoplasms
  • Proto-Oncogene Proteins c-bcl-6
  • B-Lymphocytes
  • Cancer Gene Expression Regulation
  • Immunohistochemistry
  • Oligonucleotide Array Sequence Analysis
  • Childhood Cancer
  • Chromosome Aberrations
  • myc Genes
  • Chromosome 18
Tag cloud generated 28 February, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: BCL6 (cancer-related)

Horn H, Staiger AM, Vöhringer M, et al.
Diffuse large B-cell lymphomas of immunoblastic type are a major reservoir for MYC-IGH translocations.
Am J Surg Pathol. 2015; 39(1):61-6 [PubMed] Related Publications
The immunoblastic variant of diffuse large B-cell lymphoma (IB-DLBCL) has recently been recognized as an aggressive lymphoma type with inferior prognosis as compared with other DLBCL variants. At the same time, the presence of MYC rearrangements in DLBCL has been shown to indicate shorter survival in R-CHOP-treated patients. In this study, we investigated the occurrence of MYC gene rearrangements in IB-DLBCL versus non-IB-DLBCL in a large series. Using fluorescence in situ hybridization with an MYC break-apart and MYC-IGH fusion probe, we found that 13/39 evaluable IB-DLBCLs (33%) harbor translocations involving MYC, in contrast with only 5/68 (7%) in the non-IB-DLBCL group (P<0.01). The immunoglobulin heavy chain gene (IGH) was the translocation partner in all rearrangements (100%) involving MYC in IB-DLBCL, which is in contrast to what has been reported for DLBCL in the literature (50% to 70%). Moreover, MYC rearrangements occurred as the sole translocation in the majority of cases (77%), whereas across all DLBCLs the majority of MYC-rearranged cases carry additional rearrangements of either BCL2 and/or BCL6 genes (between 58% and 83% of cases). Finally, MYC-rearranged IB-DLBCLs were CD10 positive in 62% (8/13), whereas this was an uncommon feature in MYC germline IB-DLBCLs (15%). In conclusion, IB-DLBCLs are genetically characterized by frequent MYC-IGH translocations that often occur without additional BCL2 and/or BCL6 translocations. The activation of MYC, therefore, may be an important pathogenetic feature in IB-DLBCL.

Wong Y, Abdul-Rahman F, Samsudin AT, Masir N
A case of t(14; 18)-negative follicular lymphoma with atypical immunophenotype: usefulness of immunoarchitecture of Ki67, CD79a and follicular dendritic cell meshwork in making the diagnosis.
Malays J Pathol. 2014; 36(2):125-9 [PubMed] Related Publications
Follicular lymphoma is characterised by the t(14;18)(q32;q21) chromosomal translocation causing BCL2 protein overexpression. A proportion of follicular lymphomas do not carry the t(14;18) translocation and lacked BCL2 protein expression. We describe a case of a BCL2 protein- and t(14;18)-negative follicular lymphoma that caused diagnostic difficulty. The usefulness of several immunomarkers including Ki67, CD79a and CD21 in aiding the diagnosis is discussed. The patient is a 51-year-old male who presented with gradually enlarging lymphadenopathy. Histopathological examination of the lymph node showed complete architectural effacement by neoplastic follicles containing expanded CD21-positive follicular dendritic cell meshwork. The neoplastic cells expressed pan-B cell markers (CD20, CD79a) and germinal centre marker (BCL6) but not BCL2 and CD10. Of interest are the staining patterns of Ki67 and CD79a. We observed that the Ki67- positive proliferating cells were evenly distributed within the neoplastic follicles without zonation. In addition, CD79a was homogeneously strong within the neoplastic follicles. These staining patterns were distinctly different from that observed in reactive lymphoid follicles. Fluorescent insitu hybridisation (FISH) analysis however showed absence of BCL2 gene rearrangement. Despite the atypical immunophenotype and lack of BCL2 gene rearrangement, the diagnosis of follicular lymphoma was made based on careful observation of the morphology as well as immunoarchitecture of the Ki67, CD79a and CD21 markers.

Petrich AM, Nabhan C, Smith SM
MYC-associated and double-hit lymphomas: a review of pathobiology, prognosis, and therapeutic approaches.
Cancer. 2014; 120(24):3884-95 [PubMed] Related Publications
Aberrant expression of the v-myc avian myelocytomatosis viral oncogene homolog (MYC) proto-oncogene has known transformative potential in healthy human cells. Chromosomal MYC rearrangements and consequent MYC overexpression is the defining lesion in Burkitt lymphoma (BL), conferring a highly proliferative state. However, abnormalities of MYC are increasingly appreciated in non-BL histologies, including diffuse large B-cell lymphoma (DLBCL) and B-cell lymphomas intermediate between BL and DLBCL, with a particularly aggressive clinical phenotype. Although there are conflicting data regarding prognostic implications of isolated MYC aberrancy in these non-BLs, the co-occurrence of MYC rearrangements and either the antiapoptotic gene B-cell chronic lymphocytic leukemia/lymphoma 2 (BCL2) or the transcriptional repressor BCL6 leads to an entity termed double-hit B-cell lymphoma (DHL) (or triple-hit if all 3 abnormalities are observed) with a particularly poor prognosis and no established treatment paradigms. Notably, a distinct pattern of gene expression profiling has been noted when MYC is overexpressed in BL compared with other lymphomas, supporting the notion that, although MYC promotes target gene transcription, the target genes vary by disease subtype. The frequency of MYC activity depends on the method of detection and ranges from 5% to 10% using fluorescence in situ hybridization but up to 30% of DLBCL using immunohistochemistry. Standard therapies developed for DLBCL are less effective when the disease is driven by MYC, leading to lower response rates and response durations. An important clinical challenge is to pre-emptively identify MYC-associated lymphomas and to subsequently develop trials specifically for this group of patients. However, the design of such studies is complicated by variable definitions of MYC-associated lymphoid malignancies and the lack of effective therapies to date. The objective if the current review was to evaluate the implications of MYC aberrancy with respect to the B-cell lymphoma double-hit and triple-hit phenotypes and to consider the available data for clinical and practical management.

Ruggieri S, Tamma R, Marzullo A, et al.
Translocation of the proto-oncogene Bcl-6 in human glioblastoma multiforme.
Cancer Lett. 2014; 353(1):41-51 [PubMed] Related Publications
Bcl-6 translocation is a genetic alteration that is commonly detected in Primary Central Nervous System Lymphoma. The role of this protein in cerebral tumors is unclear. In this study we investigated Bcl-6 translocation and its transcriptional and translational levels in formalin-fixed, paraffin-embedded cerebral tissue sections from glioblastoma (GBM), low-grade glioma (Astrocytoma grade II and III), and meningioma patients, and correlated them with apoptotic processes and p53 and caspase-3 expression. The results showed a frequency of 36.6% of Bcl-6 translocation in GBM patients and a decreased expression in low-grade glioma patients, correlated with the severity of the disease. Bcl-6 translocation induced an overexpression of both Bcl-6 protein and messenger in GBM, inhibiting apoptotic processes and caspases 3 expression. On the contrary, in low-grade gliomas and meningiomas Bcl-6 expression was reduced, resulting in an increase of apoptotic processes. Finally, p53 expression levels in brain tumors were comparable to Bcl-6 levels. Overall, these data demonstrate, for the first time, that the Bcl-6 gene translocates in GBM patients and that its translocation and expression are correlated with apoptosis inhibition, indicating a key role for this gene in the control of cellular proliferation. This study offers further insights into glioblastoma biology, and supports Bcl-6 as a new diagnostic marker to evaluate the disease severity.

Choe JY, Bisig B, de Leval L, Jeon YK
Primary γδ T cell lymphoma of the lung: report of a case with features suggesting derivation from intraepithelial γδ T lymphocytes.
Virchows Arch. 2014; 465(6):731-6 [PubMed] Related Publications
T cell lymphoma of γδ T cell origin is a rare disease that mainly involves extranodal sites and shows aggressive clinical behavior. Here, we report a case of primary γδ T cell lymphoma of the lungs with epitheliotropism in the respiratory epithelium, a feature somewhat reminiscent of what is observed in enteropathy-associated T cell lymphoma. A 63-year-old man presented with chest pain and dyspnea on exertion, weight loss, and general weakness. On a positron emission tomography (PET) scan, multiple hypermetabolic lesions were found in both lungs. Microscopic examination of the wedge lung biopsy revealed nodular infiltration of monomorphic, medium- to large-sized atypical lymphocytes with round nuclei, coarse chromatin, and a variable amount of clear to eosinophilic cytoplasm. Of note, intraepithelial lymphocytosis by atypical lymphoid cells was observed in the respiratory epithelium within and around the nodule. Immunohistochemically, the tumor cells were CD3+, TCRβF1-, TCRγ+, CD5-, CD7+, CD20-, CD79a-, CD30-, CD4-, CD8-, CD10-, BCL6-, CD21-, CD56+, CD57-, and CD138-, and expressed cytotoxic molecules. Epstein-Barr virus (EBV) was not detected by an in situ hybridization assay for EBV-encoded RNA. Interestingly, CD103 was expressed by a subset of tumor cells, especially those infiltrating the epithelium. T cell clonality was detected by multiplex PCR analysis of TRG and TRD gene rearrangements. After 2 months of systemic chemotherapy, PET scan showed regression of the size and metabolic activity of the lesions. This case represents a unique γδ T cell lymphoma of the lungs showing epitheliotropism by CD103+ γδ T cells that is suggestive of tissue-resident γδ T cells as the cell of origin.

Oki Y, Noorani M, Lin P, et al.
Double hit lymphoma: the MD Anderson Cancer Center clinical experience.
Br J Haematol. 2014; 166(6):891-901 [PubMed] Related Publications
We report our experience with 129 cases of double hit lymphoma (DHL), defined as B-cell lymphoma with translocations and/or extra signals involving MYC plus BCL2 and/or BCL6. All cases were reviewed for histopathological classification. Median age was 62 years (range, 18-85), 84% of patients had advanced-stage disease, and 87% had an International Prognostic Index score ≥2. Fourteen patients (11%) had a history of low-grade follicular lymphoma. MYC translocation was present in 81%, and extra signals of MYC in 25% of patients. IGH-BCL2 translocation was present in 84% and extra signals of BCL2 in 12% of patients. Two-year event-free survival (EFS) rates in all patients and patients who received R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone), R-EPOCH (rituximab, etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin), and R-HyperCVAD/MA (rituximab, hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone, alternating with cytarabine plus methotrexate) were 33%, 25%, 67% and 32%, respectively. In patients achieving complete response with initial therapy (n = 71), 2-year EFS rates in patients who did (n = 23) or did not (n = 48) receive frontline stem cell transplantation were 68% and 53%, respectively (P = 0·155). The cumulative incidence of central nervous system involvement was 13% at 3 years. Multivariate analysis identified performance status ≥2 and bone marrow involvement as independent adverse prognostic factors for EFS and OS. Further research is needed to identify predictive and/or targetable biological markers and novel therapeutic approaches for DHL patients.

Wu Q, Liu X, Yan H, et al.
B-cell lymphoma 6 protein stimulates oncogenicity of human breast cancer cells.
BMC Cancer. 2014; 14:418 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: B-cell lymphoma 6 (BCL6) protein, an evolutionarily conserved zinc finger transcription factor, showed to be highly expressed in various human cancers in addition to malignancies in the lymphoid system. This study investigated the role of BCL6 expression in breast cancer and its clinical significance in breast cancer patients.
METHODS: Expression of BCL6 protein was assessed using in situ hybridization and immunohistochemistry in 127 breast cancer patients and 50 patients with breast benign disease as well as in breast cell lines. Expression of BCL6 was restored or knocked down in two breast cancer cell lines (MCF-7 and T47D) using BCL6 cDNA and siRNA, respectively. The phenotypic change of these breast cancer cell lines was assessed using cell viability MTT, Transwell invasion, colony formation, and flow cytometry assays and in a xenograft mice model. Luciferase reporter gene, immunoblot, and qRT-PCR were used to investigate the molecular events after manipulated BCL6 expression in breast cancer cells.
RESULTS: BCL6 protein was highly expressed in breast cancer cell lines and tissue specimens and expression of BCL6 protein was associated with disease progression and poor survival of breast cancer patients. In vitro, the forced expression of BCL6 results in increased proliferation, anchorage-independent growth, migration, invasion and survival of breast cancer cell lines, whereas knockdown of BCL6 expression reduced these oncogenic properties of breast cancer cells. Moreover, forced expression of BCL6 increased tumor growth and invasiveness in a nude mouse xenograft model. At the gene level, BCL6 was a target gene of miR-339-5p. Expression of BCL6 induced expression of CXCR4 and cyclinD1 proteins.
CONCLUSIONS: The current study demonstrated the oncogenic property of BCL6 in breast cancer and further study could target BCL6 as a novel potential therapeutic strategy for breast cancer.

Bellas C, García D, Vicente Y, et al.
Immunohistochemical and molecular characteristics with prognostic significance in diffuse large B-cell lymphoma.
PLoS One. 2014; 9(6):e98169 [PubMed] Free Access to Full Article Related Publications
Diffuse large B-cell lymphoma (DLBCL) is an aggressive non-Hodgkin lymphoma with marked biologic heterogeneity. We analyzed 100 cases of DLBCL to evaluate the prognostic value of immunohistochemical markers derived from the gene expression profiling-defined cell origin signature, including MYC, BCL2, BCL6, and FOXP1 protein expression. We also investigated genetic alterations in BCL2, BCL6, MYC and FOXP1 using fluorescence in situ hybridization and assessed their prognostic significance. BCL6 rearrangements were detected in 29% of cases, and BCL6 gene alteration (rearrangement and/or amplification) was associated with the non-germinal center B subtype (non-GCB). BCL2 translocation was associated with the GCB phenotype, and BCL2 protein expression was associated with the translocation and/or amplification of 18q21. MYC rearrangements were detected in 15% of cases, and MYC protein expression was observed in 29% of cases. FOXP1 expression, mainly of the non-GCB subtype, was demonstrated in 37% of cases. Co-expression of the MYC and BCL2 proteins, with non-GCB subtype predominance, was observed in 21% of cases. We detected an association between high FOXP1 expression and a high proliferation rate as well as a significant positive correlation between MYC overexpression and FOXP1 overexpression. MYC, BCL2 and FOXP1 expression were significant predictors of overall survival. The co-expression of MYC and BCL2 confers a poorer clinical outcome than MYC or BCL2 expression alone, whereas cases negative for both markers had the best outcomes. Our study confirms that DLBCL, characterized by the co-expression of MYC and BCL2 proteins, has a poor prognosis and establishes a significant positive correlation with MYC and FOXP1 over-expression in this entity.

Guo Y, Takeuchi I, Karnan S, et al.
Array-comparative genomic hybridization profiling of immunohistochemical subgroups of diffuse large B-cell lymphoma shows distinct genomic alterations.
Cancer Sci. 2014; 105(4):481-9 [PubMed] Related Publications
Diffuse large B-cell lymphoma (DLBCL) displays striking heterogeneity at the clinical, genetic and molecular levels. Subtypes include germinal center B-cell-like (GCB) DLBCL and activated B-cell-like (ABC) DLBCL, according to microarray analysis, and germinal center type or non-germinal center type by immunohistochemistry. Although some reports have described genomic aberrations based upon microarray classification system, genomic aberrations based upon immunohistochemical classifications have rarely been reported. The present study aimed to ascertain the relationship between genomic aberrations and subtypes identified by immunohistochemistry, and to study the pathogenetic character of Chinese DLBCL. We conducted immunohistochemistry using antibodies against CD10, BCL6 and MUM1 in 59 samples of DLBCL from Chinese patients, and then performed microarray-based comparative genomic hybridization for each case. Characteristic genomic differences were found between GCB and non-GCB DLBCL from the array data. The GCB type was characterized by more gains at 7q (7q22.1, P < 0.05) and losses at 16q (P ≤ 0.05), while the non-GCB type was characterized by gains at 11q24.3 and 3q13.2 (P < 0.05). We found completely different mutations in BCL6+ and BCL6- non-GCB type DLBCL, whereby the BCL6- group had a higher number of gains at 1q and a loss at 14q32.13 (P ≤ 0.005), while the BCL6+ group showed a higher number of gains at 14q23.1 (P = 0.15) and losses at 6q (P = 0.07). The BCL6- group had a higher frequency of genomic imbalances compared to the BCL6+ group. In conclusion, the BCL6+ and BCL6- non-GCB type of DLBCL appear to have different mechanisms of pathogenesis.

Kharabi Masouleh B, Geng H, Hurtz C, et al.
Mechanistic rationale for targeting the unfolded protein response in pre-B acute lymphoblastic leukemia.
Proc Natl Acad Sci U S A. 2014; 111(21):E2219-28 [PubMed] Free Access to Full Article Related Publications
The unfolded protein response (UPR) pathway, a stress-induced signaling cascade emanating from the endoplasmic reticulum (ER), regulates the expression and activity of molecules including BiP (HSPA5), IRE1 (ERN1), Blimp-1 (PRDM1), and X-box binding protein 1 (XBP1). These molecules are required for terminal differentiation of B cells into plasma cells and expressed at high levels in plasma cell-derived multiple myeloma. Although these molecules have no known role at early stages of B-cell development, here we show that their expression transiently peaks at the pre-B-cell receptor checkpoint. Inducible, Cre-mediated deletion of Hspa5, Prdm1, and Xbp1 consistently induces cellular stress and cell death in normal pre-B cells and in pre-B-cell acute lymphoblastic leukemia (ALL) driven by BCR-ABL1- and NRAS(G12D) oncogenes. Mechanistically, expression and activity of the UPR downstream effector XBP1 is regulated positively by STAT5 and negatively by the B-cell-specific transcriptional repressors BACH2 and BCL6. In two clinical trials for children and adults with ALL, high XBP1 mRNA levels at the time of diagnosis predicted poor outcome. A small molecule inhibitor of ERN1-mediated XBP1 activation induced selective cell death of patient-derived pre-B ALL cells in vitro and significantly prolonged survival of transplant recipient mice in vivo. Collectively, these studies reveal that pre-B ALL cells are uniquely vulnerable to ER stress and identify the UPR pathway and its downstream effector XBP1 as novel therapeutic targets to overcome drug resistance in pre-B ALL.

Gebauer N, Gollub W, Stassek B, et al.
MicroRNA signatures in subtypes of follicular lymphoma.
Anticancer Res. 2014; 34(5):2105-11 [PubMed] Related Publications
BACKGROUND: MicroRNAs are regulators of gene expression implicated in vital cellular processes including differentiation, cell growth and apoptosis. Distinct microRNA signatures have been identified for many malignancies including follicular lymphoma (FL). However, no microRNA expression profile characteristic of FL subtypes, e.g. FL with B-cell lymphoma-6 (BCL6) locus rearrangement (FL(BCL2+/BCL6+), FL(BCL2-/BCL6+)) or FL with diffuse growth pattern have been reported.
MATERIALS AND METHODS: MicroRNA signatures from 44 cases of FL were generated employing a quantitative real-time polymerase chain reaction approach. 15 cases of diffuse FL and 15 cases of FL(BCL2+/BCL6+)/FL(BCL2-/BCL6+) were compared against 14 cases of typical FL(BCL2+/BCL6-).
RESULTS: Numerous microRNAs were found to be differentially expressed between FL(BCL2+/BCL6+) and FL(BCL2-/BCL6+), as well as diffuse FL, when compared to typical cases of FL. Up-regulation of several oncogenic microRNAs as well as down-regulation of tumor-suppressor microRNAs was identified. Cluster analysis, however, revealed no microRNA signatures distinct from the reference group for either subtype.
CONCLUSION: These results indicate an involvement of microRNAs in the pathogenesis of FL and its subtypes. Marked de-regulation of oncogenic RNAs and tumor suppressors appears to correspond with a more aggressive phenotype frequently observed in FL(BCL2+/BCL6+), FL(BCL2-/BCL6+) and diffuse FL.

Landsburg DJ, Nasta SD, Svoboda J, et al.
'Double-Hit' cytogenetic status may not be predicted by baseline clinicopathological characteristics and is highly associated with overall survival in B cell lymphoma patients.
Br J Haematol. 2014; 166(3):369-74 [PubMed] Related Publications
'Double-Hit' (DH) B cell non-Hodgkin lymphomas are characterized by the presence of a MYC rearrangement and additional rearrangement(s) most commonly involving BCL2 and/or BCL6. Patients with DH lymphomas are unlikely to achieve long-term survival when treated with standard immunochemotherapy alone. DH gene rearrangements can be identified through metaphase karyotyping or more sensitive fluorescence in situ hybridization (FISH), although the latter is not routinely performed. We report 53 cases of B cell lymphoma that underwent diagnostic metaphase karyotying or FISH for MYC rearrangements. DH lymphoma was detected in 17 cases. No baseline factor, including age, serum lactate dehydrogenase, stage, International Prognostic Index or histology predicted for DH status. The median overall survival was significantly shorter for DH compared to non-DH lymphoma patients (8·2 vs. 56·8 months, P < 0·001). DH status retained the most statistically significant association with overall survival on multivariate Cox regression analysis. DH status could not be inferred by baseline disease- or patient-related characteristics and was most predictive of overall survival in this cohort of B cell lymphoma patients. These findings support the practice of routine performance of FISH for DH gene rearrangements on B cell lymphoma specimens in order to effectively identify DH patients who may benefit from risk-adapted therapy.

Munoz J, Dhillon N, Janku F, et al.
STAT3 inhibitors: finding a home in lymphoma and leukemia.
Oncologist. 2014; 19(5):536-44 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
The Janus kinase (JAK) and signal transducer and activator of transcription (STAT) pathway is an active mediator of cytokine signaling in the pathogenesis of solid and hematologic malignancies. The seven-member STAT family is composed of latent cytoplasmic transcription factors that are activated by phosphorylation intertwined in a network with activation that ultimately leads to cell proliferation. An activated kinase enzyme phosphorylates one STAT factor or more, which shuttle to the nucleus to regulate gene expression, promoting cell survival. Somatic STAT3 mutations have been recently reported in large granular lymphocytic leukemia, aplastic anemia, and myelodysplastic syndrome. Furthermore, the relationship between BCL6 and STAT3 in diffuse large B-cell lymphomas, particularly on the activated B-cell subtype, needs to be further explored. The search for therapeutic STAT3 inhibitors that abrogate the JAK/STAT pathway is currently under way. Targeting the STAT pathway, which seems to be critical in tumorigenesis, is promising for multiple malignancies including lymphoma and leukemia. In this paper, we review mechanisms of action, failures, and successes of STAT3 inhibitors.

Cox MC, Di Napoli A, Scarpino S, et al.
Clinicopathologic characterization of diffuse-large-B-cell lymphoma with an associated serum monoclonal IgM component.
PLoS One. 2014; 9(4):e93903 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
Recently, diffuse-large-B-cell lymphoma (DLBCL) associated with serum IgM monoclonal component (MC) has been shown to be a very poor prognostic subset although, detailed pathological and molecular data are still lacking. In the present study, the clinicopathological features and survival of IgM-secreting DLBCL were analyzed and compared to non-secreting cases in a series of 151 conventional DLBCL treated with R-CHOP. IgM MC was detected in 19 (12.5%) out of 151 patients at disease onset. In 17 of these cases secretion was likely due to the neoplastic clone, as suggested by the expression of heavy chain IgM protein in the cytoplasm of tumor cells. In IgM-secreting cases immunoblastic features (p<.0001), non-GCB-type (p = .002) stage III-IV(p = .003), ≥ 2 extra nodal sites (p<.0001), bone-marrow (p = .002), central-nervous-system (CNS) involvement at disease onset or relapse (p<.0001), IPI-score 3-5 (p = .009) and failure to achieve complete remission (p = .005), were significantly more frequent. FISH analyses for BCL2, BCL6 and MYC gene rearrangements detected only two cases harboring BCL2 gene translocation and in one case a concomitant BCL6 gene translocation was also observed. None of the IgM-secreting DLBCL was found to have L265P mutation of MYD88 gene. Thirty-six month event-free (11.8% vs 66.4% p<.0001), progression-free (23.5% vs 75.7%, p<.0001) and overall (47.1% vs 74.8%, p<.0001) survivals were significantly worse in the IgM-secreting group. In multivariate analysis IgM-secreting (p = .005, expB = 0.339, CI = 0.160-0.716) and IPI-score 3-5 (p = .010, expB = 0.274, CI = 0.102-0.737) were the only significant factors for progression-free-survival. Notably, four relapsed patients, who were treated with salvage immunochemotherapy combined with bortezomib or lenalidomide, achieved lasting remission. Our data suggests that IgM-secreting cases are a distinct subset of DLBCL, originating from activated-B-cells with terminally differentiated features, prevalent extra nodal dissemination and at high risk of CNS involvement.

Hwang HS, Park CS, Yoon DH, et al.
High concordance of gene expression profiling-correlated immunohistochemistry algorithms in diffuse large B-cell lymphoma, not otherwise specified.
Am J Surg Pathol. 2014; 38(8):1046-57 [PubMed] Related Publications
Diffuse large B-cell lymphoma (DLBCL) is classified into prognostically distinct germinal center B-cell (GCB) and activated B-cell subtypes by gene expression profiling (GEP). Recent reports suggest the role of GEP subtypes in targeted therapy. Immunohistochemistry (IHC) algorithms have been proposed as surrogates of GEP, but their utility remains controversial. Using microarray, we examined the concordance of 4 GEP-correlated and 2 non-GEP-correlated IHC algorithms in 381 DLBCLs, not otherwise specified. Subtypes and variants of DLBCL were excluded to minimize the possible confounding effect on prognosis and phenotype. Survival was analyzed in 138 cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP)-treated and 147 rituximab plus CHOP (R-CHOP)-treated patients. Of the GEP-correlated algorithms, high concordance was observed among Hans, Choi, and Visco-Young algorithms (total concordance, 87.1%; κ score: 0.726 to 0.889), whereas Tally algorithm exhibited slightly lower concordance (total concordance 77.4%; κ score: 0.502 to 0.643). Two non-GEP-correlated algorithms (Muris and Nyman) exhibited poor concordance. Compared with the Western data, incidence of the non-GCB subtype was higher in all algorithms. Univariate analysis showed prognostic significance for Hans, Choi, and Visco-Young algorithms and BCL6, GCET1, LMO2, and BCL2 in CHOP-treated patients. On multivariate analysis, Hans algorithm retained its prognostic significance. By contrast, neither the algorithms nor individual antigens predicted survival in R-CHOP treatment. The high concordance among GEP-correlated algorithms suggests their usefulness as reliable discriminators of molecular subtype in DLBCL, not otherwise specified. Our study also indicates that prognostic significance of IHC algorithms may be limited in R-CHOP-treated Asian patients because of the predominance of the non-GCB type.

Bakhirev AG, Vasef MA, Zhang QY, et al.
Fluorescence immunophenotyping and interphase cytogenetics (FICTION) detects BCL6 abnormalities, including gene amplification, in most cases of nodular lymphocyte-predominant Hodgkin lymphoma.
Arch Pathol Lab Med. 2014; 138(4):538-42 [PubMed] Related Publications
CONTEXT: BCL6 translocations are a frequent finding in B-cell lymphomas of diverse subtypes, including some cases of nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL). However, reliable analysis of BCL6 rearrangements using fluorescence in situ hybridization is difficult in NLPHL because of the relative paucity of neoplastic cells. Combined immunofluorescence microscopy and fluorescence in situ hybridization, or fluorescence immunophenotyping and interphase cytogenetics as a tool for the investigation of neoplasms (FICTION), permits targeted analysis of neoplastic cells.
OBJECTIVE: To better define the spectrum of BCL6 abnormalities in NLPHL using FICTION analysis.
DESIGN: We performed an optimized FICTION analysis of 24 lymph nodes, including 11 NLPHL, 5 follicular hyperplasia with prominent progressive transformation of germinal centers, and 8 follicular hyperplasia without progressive transformation of germinal centers.
RESULTS: BCL6 rearrangement was identified in 5 of 11 cases of NLPHL (46%). In addition, BCL6 gene amplification, with large clusters of BCL6 signals in the absence of chromosome 3 aneuploidy, was detected in 3 of 11 cases of NLPHL (27%). One NLPHL showed extra copies of BCL6 present in conjunction with multiple copies of chromosome 3. Altogether, we detected BCL6 abnormalities in 9 of 11 cases of NLPHL (82%). None of the progressive transformation of germinal centers or follicular hyperplasia cases showed BCL6 abnormalities by FICTION.
CONCLUSIONS: To our knowledge, this is the first report of BCL6 gene amplification in NLPHL. Our optimized protocol for FICTION permits detection of cytogenetic abnormalities in most NLPHL cases and may represent a useful ancillary diagnostic technique.

Akay OM, Aras BD, Isiksoy S, et al.
BCL2, BCL6, IGH, TP53, and MYC protein expression and gene rearrangements as prognostic markers in diffuse large B-cell lymphoma: a study of 44 Turkish patients.
Cancer Genet. 2014; 207(3):87-93 [PubMed] Related Publications
The purpose of this study was to determine the frequency of BCL2, BCL6, IGH, TP53, and MYC protein expression and rearrangements of the respective genes in diffuse large B-cell lymphoma (DLBCL) patients and to assess their prognostic values. Samples from 44 patients with DLBCL were evaluated using fluorescence in situ hybridization and immunohistochemical analyses. BCL6 was the most rearranged gene (63.6%), followed by MYC (31.8%), TP53 (22.7%), and BCL2 (18.2%). Multiple rearrangements were detected in 40.9% of the cases. BCL6 was the most expressed protein (78.6%), followed by TP53 (69.04%), BCL2 (59.5%) and MYC (14.3%). Expression of multiple proteins was detected in 67.4% of the cases. BCL2 (P = .003) expression had a significant negative influence on overall survival,whereas BCL6 (P = .014) expression had a significant positive influence. Our results with a different pattern of gene rearrangements and associated protein overexpression indicate the molecular genetic complexity of DLBCLs, which reflects the morphologic, biologic, and clinical heterogeneity of these lymphomas.

Ok CY, Xu-Monette ZY, Tzankov A, et al.
Prevalence and clinical implications of cyclin D1 expression in diffuse large B-cell lymphoma (DLBCL) treated with immunochemotherapy: a report from the International DLBCL Rituximab-CHOP Consortium Program.
Cancer. 2014; 120(12):1818-29 [PubMed] Related Publications
BACKGROUND: Cyclin D1 expression has been reported in a subset of patients with diffuse large B-cell leukemia (DLBCL), but studies have been few and generally small, and they have demonstrated no obvious clinical implications attributable to cyclin D1 expression.
METHODS: The authors reviewed 1435 patients who were diagnosed with DLBCL as part of the International DLBCL rituximab with cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone (R-CHOP) Consortium Program and performed clinical, immunohistochemical, and genetic analyses with a focus on cyclin D1. All patients who were cyclin D1-positive according to immunohistochemistry were also assessed for rearrangements of the cyclin D1 gene (CCND1) using fluorescence in situ hybridization. Gene expression profiling was performed to compare patients who had DLBCL with and without cyclin D1 expression.
RESULTS: In total, 30 patients (2.1%) who had DLBCL that expressed cyclin D1 and lacked CCND1 gene rearrangements were identified. Patients with cyclin D1-positive DLBCL had a median age of 57 years (range, 16.0-82.6 years). There were 23 males and 7 females. Twelve patients (40%) had bulky disease. None of them expressed CD5. Two patients expressed cyclin D2. Gene expression profiling indicated that 17 tumors were of the germinal center type, and 13 were of the activated B-cell type. Genetic aberrations of B-cell leukemia/lymphoma 2 (BCL2), BCL6, v-myc avian myelocytomatosis viral oncogene homolog (MYC), mouse double minute 2 oncogene E3 ubiquitin protein ligase (MDM2), MDM4, and tumor protein 53 (TP53) were rare or absent. Gene expression profiling did not reveal any striking differences with respect to cyclin D1 in DLBCL.
CONCLUSIONS: Compared with patients who had cyclin D1-negative DLBCL, men were more commonly affected with cyclin D1-positive DLBCL, and they were significantly younger. There were no other significant differences in clinical presentation, pathologic features, overall survival, or progression-free survival between these two subgroups of patients with DLBCL.

Lossos C, Bayraktar S, Weinzierl E, et al.
LMO2 and BCL6 are associated with improved survival in primary central nervous system lymphoma.
Br J Haematol. 2014; 165(5):640-8 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
Primary central nervous system lymphoma (PCNSL) is an aggressive sub-variant of non-Hodgkin lymphoma (NHL) with morphological similarities to diffuse large B-cell lymphoma (DLBCL). While methotrexate (MTX)-based therapies have improved patient survival, the disease remains incurable in most cases and its pathogenesis is poorly understood. We evaluated 69 cases of PCNSL for the expression of HGAL (also known as GCSAM), LMO2 and BCL6 - genes associated with DLBCL prognosis and pathobiology, and analysed their correlation to survival in 49 PCNSL patients receiving MTX-based therapy. We demonstrate that PCNSL expresses LMO2, HGAL(also known as GCSAM) and BCL6 proteins in 52%, 65% and 56% of tumours, respectively. BCL6 protein expression was associated with longer progression-free survival (P = 0·006) and overall survival (OS, P = 0·05), while expression of LMO2 protein was associated with longer OS (P = 0·027). Further research is needed to elucidate the function of BCL6 and LMO2 in PCNSL.

Yamamoto Y, Abe A, Emi N
Clarifying the impact of polycomb complex component disruption in human cancers.
Mol Cancer Res. 2014; 12(4):479-84 [PubMed] Related Publications
The dysregulation of proper transcriptional control is a major cause of developmental diseases and cancers. Polycomb proteins form chromatin-modifying complexes that transcriptionally silence genome regions in higher eukaryotes. The BCL6 corepressor (BCOR) complex comprises ring finger protein 1B (RNF2/RING1B), polycomb group ring finger 1 (PCGF1), and lysine-specific demethylase 2B (KDM2B) and is uniquely recruited to nonmethylated CpG islands, where it removes histone H3K36me2 and induces repressive histone H2A monoubiquitylation. Germline BCOR mutations have been detected in patients with oculofaciocardiodental and Lenz microphthalmia syndromes, which are inherited conditions. Recently, several variants of BCOR and BCOR-like 1 (BCORL1) chimeric fusion transcripts were reported in human cancers, including acute promyelocytic leukemia, bone sarcoma, and hepatocellular carcinoma. In addition, massively parallel sequencing has identified inactivating somatic BCOR and BCORL1 mutations in patients with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia, medulloblastoma, and retinoblastoma. More importantly, patients with AML and MDS with BCOR mutations exhibit poor prognosis. This perspective highlights the detection of BCOR mutations and fusion transcripts of BCOR and BCORL1 and discusses their importance for diagnosing cancer subtypes and estimating the treatment responses of patients. Furthermore, this perspective proposes the need for additional functional studies to clarify the oncogenic mechanism by which BCOR and BCORL1 are disrupted in cancers, and how this may lead to the development of novel therapeutics.

Beider K, Darash-Yahana M, Blaier O, et al.
Combination of imatinib with CXCR4 antagonist BKT140 overcomes the protective effect of stroma and targets CML in vitro and in vivo.
Mol Cancer Ther. 2014; 13(5):1155-69 [PubMed] Related Publications
Functional role of CXCR4 in chronic myelogenous leukemia (CML) progression was evaluated. Elevated CXCR4 significantly increased the in vitro survival and proliferation in response to CXCL12. CXCR4 stimulation resulted in activation of extracellular signal-regulated kinase (Erk)-1/2, Akt, S6K, STAT3, and STAT5 prosurvival signaling pathways. In accordance, we found that in vitro treatment with CXCR4 antagonist BKT140 directly inhibited the cell growth and induced cell death of CML cells. Combination of BKT140 with suboptimal concentrations of imatinib significantly increased the anti-CML effect. BKT140 induced apoptotic cell death, decreasing the levels of HSP70 and HSP90 chaperones and antiapoptotic proteins BCL-2 and BCL-XL, subsequently promoting the release of mitochondrial factors cytochrome c and SMAC/Diablo. Bone marrow (BM) stromal cells (BMSC) markedly increased the proliferation of CML cells and protected them from imatinib-induced apoptosis. Furthermore, BMSCs elevated proto-oncogene BCL6 expression in the CML cells in response to imatinib treatment, suggesting the possible role of BCL6 in stroma-mediated TKI resistance. BKT140 reversed the protective effect of the stroma, effectively promoted apoptosis, and decreased BCL6 levels in CML cells cocultured with BMSCs. BKT140 administration in vivo effectively reduced the growth of subcutaneous K562-produced xenografts. Moreover, the combination of BKT140 with low-dose imatinib markedly inhibited tumor growth, achieving 95% suppression. Taken together, our data indicate the importance of CXCR4/CXCL12 axis in CML growth and CML-BM stroma interaction. CXCR4 inhibition with BKT140 antagonist efficiently cooperated with imatinib in vitro and in vivo. These results provide the rational basis for CXCR4-targeted therapy in combination with TKI to override drug resistance and suppress residual disease.

Soldini D, Georgis A, Montagna C, et al.
The combined expression of VPREB3 and ID3 represents a new helpful tool for the routine diagnosis of mature aggressive B-cell lymphomas.
Hematol Oncol. 2014; 32(3):120-5 [PubMed] Related Publications
Genomic studies, such as gene expression profiling and next-generation sequencing studies, have provided new insights into the phenotypic characteristics and pathogenesis of mature aggressive B-cell lymphomas. In particular, mutations in the transcription factors ID3 and TCF3, leading to overexpression of B-cell receptor components such as VPREB3, have been shown to be specific for Burkitt lymphoma (BL) and play an important tumourigenic role by mediating the activation of the pro-survival phosphatidylinositol-3-OH kinase pathway. We performed immunohistochemical analysis by applying commercially available anti-VPREB3 antibody to a large cohort of 185 genetically and immunophenotypically characterized mature aggressive B-cell lymphomas and analyzed these results together with recent data on ID3 expression. The combined expression of both VPREB3 and ID3 was associated with a diagnosis of BL with high sensitivity (0.77), high specificity (0.75) and high negative predictive values (0.96), however, with lower positive predictive value (0.30). Double negative cases were absent in the group of BLs but could be found in approximately one third of the remaining cases of mature aggressive B-cell lymphomas. Further, we could not identify a correlation with MYC, BCL2 or BCL6 aberrations with neither VPREB3 nor ID3 expression in each of the diagnostic groups analyzed. Our results, which are in line with recently discovered mutations in next-generation sequencing studies, suggest that the combined immunohistochemical detection of VPREB3 and ID3 is applicable to the routine diagnostic in case of mature aggressive B-cell lymphomas. In particular, it represents a useful and routinely applicable diagnostic tool to exclude BL diagnosis in case of single positive or double negative cases.

Cui J, Liu Q, Cheng Y, et al.
An intravascular large B-cell lymphoma with a t(3;14)(q27;q32) translocation.
J Clin Pathol. 2014; 67(3):279-81 [PubMed] Related Publications
A 61-year-old man with no symptom was found with bilateral adrenal nodules on CT scan during a routine physical check-up. The left nodule was removed by adrenalectomy, and the patient was diagnosed with intravascular large B-cell lymphoma (IVLBCL) on pathological and immunohistochemical examinations. Using a set of dual-colour, break-apart probes and fluorescence in situ hybridisation, it was revealed that the lymphoma cells have tetraploid karyotype, with a breakpoint in BCL6 gene, which was further confirmed as a t(3;14)(q27;q32) translocation. To the best of our knowledge, this is the first report of IVLBCL with such a translocation.

Ribeiro IP, Marques F, Caramelo F, et al.
Genetic gains and losses in oral squamous cell carcinoma: impact on clinical management.
Cell Oncol (Dordr). 2014; 37(1):29-39 [PubMed] Related Publications
PURPOSE: The identification of genetic markers associated with oral cancer is considered essential to improve the diagnosis, prognosis, early tumor and relapse detection and, ultimately, to delineate individualized therapeutic approaches. Here, we aimed at identifying such markers.
METHODS: Multiplex Ligation-dependent Probe Amplification (MLPA) analyses encompassing 133 cancer-related genes were performed on a panel of primary oral tumor samples and its corresponding resection margins (macroscopically tumor-free tissue) allowing, in both types of tissue, the detection of a wide arrange of copy number imbalances on various human chromosomes.
RESULTS: We found that in tumor tissue, from the 133 cancer-related genes included in this study, those that most frequently exhibited copy number gains were located on chromosomal arms 3q, 6p, 8q, 11q, 16p, 16q, 17p, 17q and 19q, whereas those most frequently exhibiting copy number losses were located on chromosomal arms 2q, 3p, 4q, 5q, 8p, 9p, 11q and 18q. Several imbalances were highlighted, i.e., losses of ERBB4, CTNNB1, NFKB1, IL2, IL12B, TUSC3, CDKN2A, CASP1, and gains of MME, BCL6, VEGF, PTK2, PTP4A3, RNF139, CCND1, FGF3, CTTN, MVP, CDH1, BRCA1, CDKN2D, BAX, as well as exon 4 of TP53. Comparisons between tumor and matched macroscopically tumor-free tissues allowed us to build a logistic regression model to predict the tissue type (benign versus malignant). In this model, the TUSC3 gene showed statistical significance, indicating that loss of this gene may serve as a good indicator of malignancy.
CONCLUSIONS: Our results point towards relevance of the above mentioned cancer-related genes as putative genetic markers for oral cancer. For practical clinical purposes, these genetic markers should be validated in additional studies.

Tzankov A, Xu-Monette ZY, Gerhard M, et al.
Rearrangements of MYC gene facilitate risk stratification in diffuse large B-cell lymphoma patients treated with rituximab-CHOP.
Mod Pathol. 2014; 27(7):958-71 [PubMed] Related Publications
In order to address the debatable prognostic role of MYC rearrangements in diffuse large B-cell lymphoma patients treated with rituximab, cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone, we evaluated MYC rearrangements by fluorescence in situ hybridization in 563 cases using break-apart probes and IGH/MYC dual-fusion probes. Concurrent BCL2 and BCL6 aberrations were also assessed. Data were correlated with clinicopathological variables and prognostic parameters. MYC rearrangements were observed in 39/432 evaluable cases (9%), including 4 rearrangements detectable only with the dual-fusion probes, 15 detectable only with the break-apart probes and 20 detectable with both dual-fusion probes and break-apart probes. MYC rearrangements correlated with germinal center B-cell origin (P=0.02), MYC protein expression (P=0.032), and larger tumor mass size (P=0.0003). Patients with MYC rearrangements were more likely to be treatment resistant (P<0.0001). All types of MYC rearrangements were associated with poorer disease-specific survival, that is, 20/39 dead, median disease-specific survival 42 months, compared with 98/393 dead among the non-rearranged cases, median disease-specific survival not reached (P=0.0002). Cases with MYC rearrangements that overexpressed MYC protein were at risk with respect to disease-specific survival independent of the International Prognostic Index (P=0.046 and P<0.001, respectively). Presence of concurrent BCL2 aberrations but not of BCL6 aberrations was prognostically additive. Radiotherapy seemed to diminish the prognostic effects of MYC rearrangements in diffuse large B-cell lymphoma patients since only 2/10 irradiated patients with MYC rearrangements died of/with disease, compared with 16/28 non-irradiated patients with MYC rearrangements. We conclude that MYC rearrangements add prognostic information for individual risk estimation and such cases might represent a distinct, biologically determined disease subgroup.

Swaminathan S, Duy C, Müschen M
BACH2-BCL6 balance regulates selection at the pre-B cell receptor checkpoint.
Trends Immunol. 2014; 35(3):131-7 [PubMed] Article available free on PMC after 01/03/2015 Related Publications
At the pre-B cell receptor (BCR) checkpoint, developing pre-B cells are selected for successful rearrangement of V(H)-DJ(H) gene segments and expression of a pre-BCR. Reduced stringency at this checkpoint may obstruct the B cell repertoire with nonfunctional B cell clones. Earlier studies have described that activation of B cell lymphoma/leukemia (BCL)6 by a functional pre-BCR mediates positive selection of pre-B cells that have passed the checkpoint. This concept is now further elaborated by the recent finding that the BTB and CNC homology 1 basic leucine zipper transcription factor 2 (BACH2) induces negative selection and opposes BCL6 function prior to the pre-BCR checkpoint. Here, we discuss the antagonism between BCL6 and BACH2 during early B cell development, as well as its implications in both repertoire selection and counter-selection of premalignant clones for leukemia suppression.

Chapuy B, McKeown MR, Lin CY, et al.
Discovery and characterization of super-enhancer-associated dependencies in diffuse large B cell lymphoma.
Cancer Cell. 2013; 24(6):777-90 [PubMed] Article available free on PMC after 01/03/2015 Related Publications
Diffuse large B cell lymphoma (DLBCL) is a biologically heterogeneous and clinically aggressive disease. Here, we explore the role of bromodomain and extra-terminal domain (BET) proteins in DLBCL, using integrative chemical genetics and functional epigenomics. We observe highly asymmetric loading of bromodomain 4 (BRD4) at enhancers, with approximately 33% of all BRD4 localizing to enhancers at 1.6% of occupied genes. These super-enhancers prove particularly sensitive to bromodomain inhibition, explaining the selective effect of BET inhibitors on oncogenic and lineage-specific transcriptional circuits. Functional study of genes marked by super-enhancers identifies DLBCLs dependent on OCA-B and suggests a strategy for discovering unrecognized cancer dependencies. Translational studies performed on a comprehensive panel of DLBCLs establish a therapeutic rationale for evaluating BET inhibitors in this disease.

Bohn O, Maeda T, Filatov A, et al.
Utility of LRF/Pokemon and NOTCH1 protein expression in the distinction between nodular lymphocyte-predominant Hodgkin lymphoma and classical Hodgkin lymphoma.
Int J Surg Pathol. 2014; 22(1):6-11 [PubMed] Article available free on PMC after 01/03/2015 Related Publications
Classical Hodgkin lymphoma (CHL) and nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) are considered separate entities with different prognosis and treatment. However, morphologic features can be similar and immunohistochemical studies are essential in the distinction; thus, determination of additional biomarkers is of utmost importance. LRF/Pokemon is a proto-oncogene, an interacting partner co-expressed with BCL6 in germinal centers and highly expressed in diffuse large B-cell lymphoma and follicular lymphoma. Conversely, loss of the LRF gene in mouse hematopoietic stem cells results in complete block of early B cell development with concomitant Notch de-repression, indicating its critical role in B versus T cell fate decision at the hematopoietic stem cell stage. For the first time, we show that LRF/Pokemon is predominantly expressed in NLPHL cases as is BCL6 with low to absent NOTCH1 protein expression; while Hodgkin Reed-Sternberg (HRS) cells in CHL show low to absent BCL6 and LRF/Pokemon expression with higher NOTCH1 expression. We illustrate a potential functional interaction between LRF and BCL6 in NLPHL pathogenesis, and differential expression of LRF/Pokemon and NOTCH1 proteins in CHL thus showing differential expression, making for an additional diagnostic marker and therapeutic target.

Ott G, Rosenwald A, Campo E
Understanding MYC-driven aggressive B-cell lymphomas: pathogenesis and classification.
Hematology Am Soc Hematol Educ Program. 2013; 2013:575-83 [PubMed] Related Publications
MYC is a potent oncogene initially identified as the target of the t(8;14)(q24;q32) chromosome translocation in Burkitt lymphoma. MYC gene alterations have been identified in other mature B-cell neoplasms that are usually associated with an aggressive clinical behavior. Most of these tumors originate in cells that do not normally express MYC protein. The oncogenic events leading to MYC up-regulation seem to overcome the inhibitory effect of physiological repressors such as BCL6 or BLIMP1. Aggressive lymphomas frequently carry additional oncogenic alterations that cooperate with MYC dysregulation, likely counteracting its proapoptotic function. The development of FISH probes and new reliable antibodies have facilitated the study of MYC gene alterations and protein expression in large series of patients, providing new clinical and biological perspectives regarding MYC dysregulation in aggressive lymphomas. MYC gene alterations in large B-cell lymphomas are frequently associated with BCL2 or BCL6 translocations conferring a very aggressive behavior. Conversely, MYC protein up-regulation may occur in tumors without apparent gene alterations, and its association with BCL2 overexpression also confers a poor prognosis. In this review, we integrate all of this new information and discuss perspectives, challenges, and open questions for the diagnosis and management of patients with MYC-driven aggressive B-cell lymphomas.

Sugimoto KJ, Imai H, Shimada A, et al.
Diffuse large B-cell lymphoma of the uterus suspected of having transformed from a marginal zone B-cell lymphoma harboring trisomy 18: a case report and review of the literature.
Int J Clin Exp Pathol. 2013; 6(12):2979-88 [PubMed] Article available free on PMC after 01/03/2015 Related Publications
The patient was a 72-year-old female with the chief complaint of abdominal fullness. A giant primary myoma of the uterine cervix was suspected, and total hysterectomy was performed. Based on a postoperative histopathological examination of the tumor a diagnosis of diffuse large B-cell lymphoma (DLBCL) was made in the uterus and a mass in the greater omentum was diagnosed as a marginal zone B-cell lymphoma (MZBCL). No flow-cytometry studies or chromosome or gene examinations were performed on a fresh specimen. The results of an examination of a paraffin block histopathology specimen by fluorescence in-situ hybridization (FISH) showed no mucosa associated lymphoid tissue lymphoma translocation gene 1 (MALT1) (18q21.1), B-cell lymphoma 2 (BCL2) (18q21.3), or BCL6 (3q27) split signals in either the uterus or the greater omentum, however, trisomy 18 was detected in approximately 50%-70% of the tumor cells in both the uterus and the greater omentum. Trisomy 18 was present in around 15-33% of the DLBCL cells and MZBCL cells. These findings suggested a strong possibility that the tumor cells in the uterus and greater omentum were the same clone and that transformation from MZBCL to DLBCL had occurred. Since DLBCLs that result from a transformation usually have a worse outcome than de novo DLBCLs, even when a DLBCL seems to have originated in the uterus the surrounding tissue should always be examined, and caution should be exercised in regard to transformation from a low-grade B-cell lymphoma to a DLBCL.

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