The BCL6 proto-oncogene: a leading role during germinal center development and lymphomagenesis

Resveratrol as a BCL6 natural inhibitor suppresses germinal center derived Non-Hodgkin lymphoma cells growth

Non-Hodgkin lymphomas (NHL), including diffuse large B-cell lymphoma (DLBCL), Burkitt lymphoma (BL), and follicular lymphoma (FL), predominantly arise from B cells undergoing germinal center (GC) reactions. The transcriptional repressor B-cell lymphoma 6 (BCL6) is indispensable for GC formation and contributes to lymphomagenesis via its BTB domain-mediated suppression of target genes. Dysregulation of BCL6 underpins the pathogenesis of GC-derived NHL. While pharmacological targeting the BCL6-BTB domain has shown therapeutic promise, natural product-based inhibitors remain underexplored. In this study, resveratrol, a polyphenolic compound derived from grapes, was identified as a potent BCL6 inhibitor through a comprehensive screen of traditional Chinese medicine monomers using Homogeneous Time-Resolved Fluorescence (HTRF) assay. As a BCL6 natural inhibitor, resveratrol effectively disrupted the BCL6/SMRT interaction, reactivated suppressed gene expression, and inhibited the proliferation of GC-derived NHL cells. It also exhibited synergistic efficacy when combined with EZH2 and PRMT5 inhibitors. In vivo, resveratrol suppressed GC formation, reduced follicular helper T-cell frequencies, impaired class-switch recombination, and disrupted immunoglobulin affinity maturation. Furthermore, it markedly inhibited the progression of GC-derived NHL in animal models. Our findings demonstrate that resveratrol functions as a natural BCL6 inhibitor with significant therapeutic potential for the treatment of GC-derived NHL.

The high-grade B-cell lymphomas: double hit and more

ABSTRACT

Both the 2022 World Health Organization Classification of Hematolymphoid Tumors, 5th Edition and the International Consensus Classification of lymphoma have refined the way we now approach high-grade B-cell lymphoma (HGBL) with MYC and BCL2 and/or BCL6 rearrangements moving the previous generation of classification a step forward. The unifying biology of MYC/BCL2 tumors has become clearer and their inferior prognosis confirmed compared with those with morphologic similar phenotypes but lacking the classifcation defining cytogenetic abnormalities. Fluorescent in situ hybridization testing has now become largely population based, and we have learned much from this. We can readily define molecular categories and apply these widely to clinical practice. Uncertainty has, however, been shed on the place of MYC/BCL6 translocations in defining a common disease group of double hit lymphoma due to biological heterogeneity. We have enhanced our knowledge of outcomes and the role of therapy intensification to overcome chemotherapy resistance in HGBL. For those patients failed by initial induction chemotherapy, immunotherapy approaches, including chimeric antigen receptor T-cell therapies, are improving outcomes. Novel inhibitors, targeting dysregulated oncogenic proteins, are being explored at pace. The rare, but difficult, diagnostic classification HGBL (not otherwise specified) remains a diagnosis of exclusion with limited data on an optimal clinical approach. The days of talking loosely of double- and triple-hit lymphoma are numbered as biology and outcomes may not be shared. This review synergizes the current data on biology, prognosis, and therapies in HGBL.

Transcriptional Inflammatory Signature in Healthy Donors and Different Radiotherapy Cancer Patients

Cancer and ionizing radiation exposure are associated with inflammation. To identify a set of radiation-specific signatures of inflammation-associated genes in the blood of partially exposed radiotherapy patients, differential expression of 249 inflammatory genes was analyzed in blood samples from cancer patients and healthy individuals. The gene expression analysis on a cohort of 63 cancer patients (endometrial, head and neck, and prostate cancer) before and during radiotherapy (24 h, 48 h, ~1 week, ~4-8 weeks, and 1 month after the last fraction) identified 31 genes and 15 up- and 16 down-regulated genes. Transcription variability under normal conditions was determined using blood drawn on three separate occasions from four healthy donors. No difference in inflammatory expression between healthy donors and cancer patients could be detected prior to radiotherapy. Remarkably, repeated sampling of healthy donors revealed an individual endogenous inflammatory signature. Next, the potential confounding effect of concomitant inflammation was studied in the blood of seven healthy donors taken before and 24 h after a flu vaccine or ex vivo LPS (lipopolysaccharide) treatment; flu vaccination was not detected at the transcriptional level and LPS did not have any effect on the radiation-induced signature identified. Finally, we identified a radiation-specific signature of 31 genes in the blood of radiotherapy patients that were common for all cancers, regardless of the immune status of patients. Confirmation via MQRT-PCR was obtained for BCL6, MYD88, MYC, IL7, CCR4 and CCR7. This study offers the foundation for future research on biomarkers of radiation exposure, radiation sensitivity, and radiation toxicity for personalized radiotherapy treatment.

Cytogenetics in the management of mature B-cell non-Hodgkin lymphomas: Guidelines from the Groupe Francophone de Cytogénétique Hematologique (GFCH)

Non-Hodgkin lymphomas (NHL) consist of a wide range of clinically, phenotypically and genetically distinct neoplasms. The accurate diagnosis of mature B-cell non-Hodgkin lymphoma relies on a multidisciplinary approach that integrates morphological, phenotypical and genetic characteristics together with clinical features. Cytogenetic analyses remain an essential part of the diagnostic workup for mature B-cell lymphomas. Karyotyping is particularly useful to identify hallmark translocations, typical cytogenetic signatures as well as complex karyotypes, all bringing valuable diagnostic and/or prognostic information. Besides the well-known recurrent chromosomal abnormalities such as, for example, t(14;18)(q32;q21)/IGH::BCL2 in follicular lymphoma, recent evidences support a prognostic significance of complex karyotype in mantle cell lymphoma and Waldenström macroglobulinemia. Fluorescence In Situ Hybridization is also a key analysis playing a central role in disease identification, especially in genetically-defined entities, but also in predicting transformation risk or prognostication. This can be exemplified by the pivotal role of MYC, BCL2 and/or BCL6 rearrangements in the diagnostic of aggressive or large B-cell lymphomas. This work relies on the World Health Organization and the International Consensus Classification of hematolymphoid tumors together with the recent cytogenetic advances. Here, we review the various chromosomal abnormalities that delineate well-established mature B-cell non-Hodgkin lymphoma entities as well as newly recognized genetic subtypes and provide cytogenetic guidelines for the diagnostic management of mature B-cell lymphomas.

Cellular Functions of Deubiquitinating Enzymes in Ovarian Adenocarcinoma

In ovarian cancer patients, the 5-year survival rate is 90% for stages I and II, but only 30% for stages III and IV. Unfortunately, as 75% of the patients are diagnosed at stages III and IV, many experience a recurrence. To ameliorate this, it is necessary to develop new biomarkers for early diagnosis and treatment. The ubiquitin-proteasome system is a post-translational modification that plays an important role in regulating protein stability through ubiquitination. In particular, deubiquitinating enzymes (DUBs) regulate protein stability through deubiquitinating substrate proteins. In this review, DUBs and substrates regulated by these enzymes are summarized based on their functions in ovarian cancer cells. This would be useful for the discovery of biomarkers for ovarian cancer and developing new therapeutic candidates.

Computer analysis of regulation of hepatocarcinoma marker genes hypermethylated by HCV proteins

Hepatitis C virus (HCV) is a risk factor that leads to hepatocellular carcinoma (HCC) development. Epigenetic changes are known to play an important role in the molecular genetic mechanisms of virus-induced oncogenesis. Aberrant DNA methylation is a mediator of epigenetic changes that are closely associated with the HCC pathogenesis and considered a biomarker for its early diagnosis. The ANDSystem software package was used to reconstruct and evaluate the statistical significance of the pathways HCV could potentially use to regulate 32 hypermethylated genes in HCC, including both oncosuppressor and protumorigenic ones identified by genome-wide analysis of DNA methylation. The reconstructed pathways included those affecting protein-protein interactions (PPI), gene expression, protein activity, stability, and transport regulations, the expression regulation pathways being statistically significant. It has been shown that 8 out of 10 HCV proteins were involved in these pathways, the HCV NS3 protein being implicated in the largest number of regulatory pathways. NS3 was associated with the regulation of 5 tumor-suppressor genes, which may be the evidence of its central role in HCC pathogenesis. Analysis of the reconstructed pathways has demonstrated that following the transcription factor inhibition caused by binding to viral proteins, the expression of a number of oncosuppressors (WT1, MGMT, SOCS1, P53) was suppressed, while the expression of others (RASF1, RUNX3, WIF1, DAPK1) was activated. Thus, the performed gene-network reconstruction has shown that HCV proteins can influence not only the methylation status of oncosuppressor genes, but also their transcriptional regulation. The results obtained can be used in the search for pharmacological targets to develop new drugs against HCV-induced HCC.

Optimizing Shape Complementarity Enables the Discovery of Potent Tricyclic BCL6 Inhibitors

To identify new chemical series with enhanced binding affinity to the BTB domain of B-cell lymphoma 6 protein, we targeted a subpocket adjacent to Val18. With no opportunities for strong polar interactions, we focused on attaining close shape complementarity by ring fusion onto our quinolinone lead series. Following exploration of different sized rings, we identified a conformationally restricted core which optimally filled the available space, leading to potent BCL6 inhibitors. Through X-ray structure-guided design, combined with efficient synthetic chemistry to make the resulting novel core structures, a >300-fold improvement in activity was obtained by the addition of seven heavy atoms.

Immunohistochemical expression of transcription factors PAX5, OCT2, BCL6 and transcription regulator P53 in Non-Hodgkin lymphomas: A diagnostic cross-sectional study

BACKGROUND

Non-Hodgkin lymphoma represents a heterogeneous group of tumors that constitute the seventh most common malignancy. Immunohistochemistry plays a major role in the detection of specific cell receptors. Transcription factors are a heterogeneous group of genes that play a critical role in the commitment, differentiation, and proliferation of specific cell types.

METHODS

Paraffin-embedded tissue sections of non-Hodgkin lymphoma cases were selected, classified, and evaluated before staining with immunohistochemical markers (PAX5, OCT2, BCL6, and P53). Expression of the aforementioned markers was compared with histological subtypes and grades of lymphoma cases. Means of expression were also compared among histological subtypes.

RESULTS

A total of 55 cases of NHL including 26 cases of low-grade lymphomas and 29 cases of high-grade lymphomas were included in the study. DLBCL and FL were the most common subtypes of high-grade and low-grade lymphomas respectively. Both PAX5 and OCT2 were positive in 44 cases of NHL (80%) including all cases of B-cell lymphomas. BCL6 and P53 demonstrated positive expression in 29.1% and 67.3% respectively. Interestingly, we found a significant association between the histological subtypes and the aforementioned markers (P-value<0.05).

DISCUSSION

Expression of PAX5, OCT2, BCL, and P53 played a major role in the diagnosis and grading of non-Hodgkin lymphomas in our study. Both PAX5 and OCT2 provided more accuracy and specificity in the diagnosis of B-cell neoplasms compared to the classical B-cell markers. BCL6 expression reflected its role in germinal center formation in normal and malignant lymphoid tissues, and expression of P53 mirrored the accumulation of gene mutations in more aggressive lymphoma subtypes.

CONCLUSION

In this manuscript, we aimed to present a unique study that highlights the immunohistochemical expression of all the aforementioned factors among various histological subtypes of non-Hodgkin lymphomas with disparities in histological aggressiveness, highlighting a promising diagnostic and prognostic panel for non-Hodgkin lymphomas.

miR-30b-5p inhibits osteoblast differentiation through targeting BCL6

Human bone marrow mesenchymal stem cells (hBMSCs) are attractive candidates for new therapies to improve bone regeneration and repair. This study was to identify the function of the miR-30b-5p/BCL6 axis in osteogenic differentiation of hBMSCs. Realtime-quantitative PCR (RT-qPCR) and Western blotting were used to measure the relative expression of ALP, OCN, RUNX2, miR-30b-5p, and BCL6 during osteogenic differentiation of hBMSCs. The relationship between miR-30b-5p and BCL6 in hBMSCs was identified using dual-luciferase reporter system and RNA pull-down assay. Alizarin red S staining (ARS) was used to detect the calcium nodules in hBMSCs. We found that the expression of miR-30b-5p was downregulated, whereas that of BCL6 was upregulated during osteogenic differentiation of hBMSCs. Downregulating miR-30b-5p enhanced the expression of OCN, RUNX2, and ALP, and promoted calcium deposition. Conversely, transfection with si-BCL6 had the opposite effect that it inhibited osteogenic differentiation. However, the inhibitory effect of si-BCL6 was abrogated by miR-30b-5p inhibitor. miR-30b-5p inhibits the osteogenic differentiation of hBMSCs by targeting BCL6.

Into Deep Water: Optimizing BCL6 Inhibitors by Growing into a Solvated Pocket

We describe the optimization of modestly active starting points to potent inhibitors of BCL6 by growing into a subpocket, which was occupied by a network of five stably bound water molecules. Identifying potent inhibitors required not only forming new interactions in the subpocket but also perturbing the water network in a productive, potency-increasing fashion while controlling the physicochemical properties. We achieved this goal in a sequential manner by systematically probing the pocket and the water network, ultimately achieving a 100-fold improvement of activity. The most potent compounds displaced three of the five initial water molecules and formed hydrogen bonds with the remaining two. Compound 25 showed a promising profile for a lead compound with submicromolar inhibition of BCL6 in cells and satisfactory pharmacokinetic (PK) properties. Our work highlights the importance of finding productive ways to perturb existing water networks when growing into solvent-filled protein pockets.

Primary diffuse large B-cell lymphoma of the sigmoid colon

Introduction

Extranodal lymphomas are commonly encountered in the gastrointestinal tract but lymphomas of colon and rectum are rare. Non-Hodgkin lymphoma is the most common type of colonic lymphoma and represents less than 0.5% of colorectal neoplasms. Chemotherapeutical agents are gateway to disease remission and sometimes cure in most patients but surgery may be necessary in emergent situations.

Case presentation

A 77-year-old male patient presented with abdominal discomfort, constipation, and obstructive defecation symptoms. Radiological imaging revealed a mass in the sigmoid colon extending towards the rectum. Colonoscopy was performed and biopsy of a nearly 10 cm ulcerovegetative lesion was obtained. Histological examination following biopsy revealed it to be a diffuse large B-cell lymphoma of the sigmoid colon. There was no indication for surgery and the patient was referred to medical oncology clinic for chemotherapy treatment.

Discussion

Non-Hodgkin lymphoma is a lymphoproliferative disorder with the diffuse large B cell lymphoma (DLBCL) being the most common subtype. The DLBCL subtype is rarely observed in the colon and rectum. Chromosomal abnormalities are involved in the pathophysiology and gene rearrangements lead to adjustments in lymphocyte function and differentiation.

Conclusion

In this case report, we present a rare presentation of a Non-Hodgkin lymphoma presenting in the sigmoid colon. The disease can present with nonspecific symptoms and various imaging modalities along with histopathological evaluation is necessary for the correct subtyping of lymphoma. Chemoradiotherapy is key for treatment, and surgery is usually reserved for cases of obstruction, perforation, or bleeding.

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Non-Hodgkin lymphoma is the most common type of colonic lymphoma.

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Extranodal lymphomas of the colon and rectum are rare.

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Histopathological evaluation is important for subtyping of lymphoma.

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Chemotherapy is the main form of treatment but sometimes surgery is required.

The mutation of BCOR is highly recurrent and oncogenic in mature T-cell lymphoma

Background

BCOR acts as a corepressor of BCL6, a potent oncogenic protein in cancers of the lymphoid lineage. We have found the recurrent somatic mutation of BCOR occurred in mature T-cell lymphoma (TCL). The role of BCOR mutation in lymphoid malignancies is unknown.

Methods

Lymphoma patient samples were analyzed to identify missense mutations in BCOR using Sanger sequencing. Transfection, RNA interference, immunoprecipitation, western blotting, cell proliferation, cytokine assays and quantitative real-time PCR were employed to determine the functional relevance of the novel K607E mutation in BCOR. The significant transcriptional changes were analyzed by performing DNA microarray profiling in cells expressing BCOR K607E mutant.

Results

One hundred thirty-seven lymphoma patient samples were analyzed to identify K607E mutation of the BCOR gene. The BCOR K607E mutation was identified in 15 of 47 NK/T cell lymphoma cases (31.9%), 2 of 18 angioimmunoblastic T-cell lymphoma cases (11.1%), 10 of 30 peripheral T-cell lymphoma, not otherwise specified cases (33.3%), and 13 of 42 diffuse large B-cell lymphoma cases (30.9%). Molecular analysis of BCOR K607E mutation revealed that compared to the wild-type BCOR, the mutant BCOR bound to the BCL6, PCGF1, and RING1B proteins with lesser affinity. Ectopic expression of BCOR K607E mutant significantly enhanced cell proliferation, AKT phosphorylation and the expression of interleukin-2 (IL-2) with up-regulated expression of HOX and S100 protein genes in T cells. BCOR silencing also significantly enhanced cell proliferation, AKT phosphorylation, and IL-2 production.

Conclusions

Functional analyses indicated that K607E mutation of BCOR is oncogenic in nature and can serve as a genetic marker of T-cell lymphoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07806-8.

Achieving In Vivo Target Depletion through the Discovery and Optimization of Benzimidazolone BCL6 Degraders

Deregulation of the transcriptional repressor BCL6 enables tumorigenesis of germinal center B-cells, and hence BCL6 has been proposed as a therapeutic target for the treatment of diffuse large B-cell lymphoma (DLBCL). Herein we report the discovery of a series of benzimidazolone inhibitors of the protein-protein interaction between BCL6 and its co-repressors. A subset of these inhibitors were found to cause rapid degradation of BCL6, and optimization of pharmacokinetic properties led to the discovery of 5-((5-chloro-2-((3R,5S)-4,4-difluoro-3,5-dimethylpiperidin-1-yl)pyrimidin-4-yl)amino)-3-(3-hydroxy-3-methylbutyl)-1-methyl-1,3-dihydro-2H-benzo[d]imidazol-2-one (CCT369260), which reduces BCL6 levels in a lymphoma xenograft mouse model following oral dosing.

Transcriptome profiling reveals the role of ZBTB38 knock-down in human neuroblastoma

ZBTB38 belongs to the zinc finger protein family and contains the typical BTB domains. As a transcription factor, ZBTB38 is involved in cell regulation, proliferation and apoptosis, whereas, functional deficiency of ZBTB38 induces the human neuroblastoma (NB) cell death potentially. To have some insight into the role of ZBTB38 in NB development, high throughput RNA sequencing was performed using the human NB cell line SH-SY5Y with the deletion of ZBTB38. In the present study, 2,438 differentially expressed genes (DEGs) in ZBTB38^−/− SH-SY5Y cells were obtained, 83.5% of which was down-regulated. Functional annotation of the DEGs in the Kyoto Encyclopedia of Genes and Genomes database revealed that most of the identified genes were enriched in the neurotrophin TRK receptor signaling pathway, including PI3K/Akt and MAPK signaling pathway. we also observed that ZBTB38 affects expression of CDK4/6, Cyclin E, MDM2, ATM, ATR, PTEN, Gadd45, and PIGs in the p53 signaling pathway. In addition, ZBTB38 knockdown significantly suppresses the expression of autophagy-related key genes including PIK3C2A and RB1CC1. The present meeting provides evidence to molecular mechanism of ZBTB38 modulating NB development and targeted anti-tumor therapies.

Double hit lymphoma: How do we define it and how do we treat it?

Double/triple hit lymphoma is recognised as a distinct entity within the heterogeneous group of high grade B-cell lymphomas, accounting for between 5 and 10% of cases of diffuse large B-cell lymphoma. Under the WHO 2016 it is now known as high-grade B-cell lymphoma with rearrangements of MYC and BCL2 and/or BCL6. When treated with standard chemotherapy it has a poor outcome. There is currently no standard of care for the management of this condition. Diagnosing double hit lymphoma requires identification of translocations of MYC and BCL2 and/or BCL6. This review will discuss the role of stratification to screen cases based on immunohistochemical profiling as a viable option. Treatment options in the frontline and relapsed setting will be reviewed based on the current literature. Recognition of the risk of CNS involvement and how best to manage this will be discussed. Future considerations and current research will be described.

miR-339-5p inhibits metastasis of non-small cell lung cancer by regulating the epithelial-to-mesenchymal transition

Metastasis is a common event in cancer pathology, and represents the primary cause of cancer-associated mortality. Metastasis, which is the process in which cancer cells at the primary tumor site spread to a different location in the body and form a new tumor, is regulated by multiple factors and includes a number of steps and stages. In our previous study, it was demonstrated miR-339-5p inhibits cell migration and invasion in vitro and is associated with the tumor-node-metastasis stage and the lymph node metastasis status of non-small cell lung cancer. In the present study, expression of miR-339-5p was first determined in the tissues and peripheral blood of patients with non-small cell lung cancer (NSCLC) and in NSCLC cell lines. It was then demonstrated that miR-339-5p inhibits A549 and H1299 cell invasion. The underlying molecular events of miR-339-5p action in NSCLC were also explored. By luciferase assay and western blot analysis, B-cell CLL/lymphoma 6 (BCL6) was verified as the direct target gene of miR-339-5p. miR-339-5p may inhibit lung cancer cell invasion and migration by regulating the epithelial-to-mesenchymal transition via BCL6 in vitro. It was also demonstrated that the relative expression of miR-339-5p in the peripheral blood is associated with cancer metastasis in patients with non-small cell lung cancer.

High expressions of BCL6 and Lewis y antigen are correlated with high tumor burden and poor prognosis in epithelial ovarian cancer

Aberrant regulation of BCL6 plays crucial oncogenic roles in various malignant tumors; howbeit, the function of BCL6 in tumorigenesis of ovarian cancer remains unclear. The aim of this study is to investigate the role of BCL6 in ovarian cancer. The methods of immunohistochemical staining, quantitative real-time polymerase chain reaction, immunocytochemical staining, and gene expression profile enrichment analysis were performed to identify the possible role of BCL6 in ovarian cancer. We observed that the expression of BCL6 was significantly higher in ovarian cancer tissues and correlated with higher tumor burden including advanced International Federation of Gynecology and Obstetrics stages, poor differentiation, Type II ovarian cancer, the presence of >1 cm residual tumor size, and appearance of recurrence or death (all p < 0.05). The expression patterns of Lewis y were similar to these of BCL6. Multivariate Cox analysis demonstrated that advanced International Federation of Gynecology and Obstetrics stage, lymph node metastasis, residual tumor size >1 cm, as well as high expressions of BCL6 and Lewis y antigen were independent factors of worse progression-free survival and overall survival (all p < 0.05). There was a positive correlation of the expressions of BCL6 and Lewis y antigen. The associated genes with BCL6 in response to Lewis y antigen were identified, including four upregulated genes ( SOCS3, STAT1, PPARG, and GADD45A) and three downregulated genes ( ACAN, E2F3, and ZBTB7B). In conclusion, the high expressions of BCL6 and Lewis y antigen are associated with development, high tumor burden, and worse prognosis of ovarian cancer and targeting BCL6 could be a novel therapeutic strategy for ovarian cancer treatment.

Tertiary lymphoid structures are confined to patients presenting with unifocal Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is a neoplastic myeloid disorder with a thus far poorly understood immune component. Tertiary lymphoid structures (TLS) are lymph node-like entities which create an immune-promoting microenvironment at tumor sites. We analyzed the presence and clinical relevance of TLS in n = 104 H&E-stained, therapy-naive LCH lesions of non-lymphoid origin and applied immunohistochemistry to a smaller series. Lymphoid-follicular aggregates were detected in 34/104 (33%) lesions. In line with the lymphocyte recruitment capacity of MECA-79(+) high endothelial venules (HEVs), MECA-79(+)-expressing-LCH lesions (37/77, 48%) contained the most CD3(+) T-lymphocytes (p = 0.003). TLS were identified in 8/15 lesions and contained T-and B-lymphocytes, Follicular Dendritic Cells (FDC), HEVs and the chemokines CXCL13 and CCL21 representing key cellular components and TLS-inducing factors in conventional lymph nodes (LN). Lymphoid-follicular aggregates were most frequently detected in patients presenting with unifocal LCH (24/70, 34%) as compared to patients with poly-ostotic or multi-system LCH (7/30, 23%, p = 0.03). In addition, patients with lymphoid-follicular aggregates-containing lesions had the lowest risk to develop new LCH lesions (p = 0.04). The identification of various stages of TLS formation within LCH lesions may indicate a key role for the immune system in controlling aberrant histiocytes which arise in peripheral tissues.

Gene expression profile analysis in response to α1,2-fucosyl transferase (FUT1) gene transfection in epithelial ovarian carcinoma cells

The aim of this study was to identify differentially expressed genes (DEGs) in response to α1,2-fucosyl transferase (FUT1) gene transfection in epithelial ovarian cancer cells. Human whole-genome oligonucleotide microarrays were used to determine whether gene expression profile may differentiate the epithelial ovarian cell line Caov-3 transfected with FUT1 from the empty plasmid-transfected cells. Quantitative real-time PCR and immunohistochemical staining validated the microarray results. Gene expression profile identified 215 DEGs according to the selection criteria, in which 122 genes were upregulated and 93 genes were downregulated. Gene Ontology (GO) and canonical pathway enrichment analysis were applied, and we found that these DEGs are involved in BioCarta mammalian target of rapamycin (mTOR) pathway, BioCarta eukaryotic translation initiation factor 4 (EIF4) pathway, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in cancer. Interaction network analysis predicted genes participating in the regulatory connection. Highly differential expression of TRIM46, PCF11, BCL6, PTEN, and FUT1 genes was validated by quantitative real-time PCR in two cell line samples. Finally, BCL6 and Lewis Y antigen were validated at the protein level by immunohistochemistry in 103 paraffin-embedded ovarian cancer tissues. The identification of genes in response to FUT1 may provide a theoretical basis for the investigations of the molecular mechanism of ovarian cancer.

MicroRNA-187 induces diffuse large B-cell lymphoma cell apoptosis via targeting BCL6

MicroRNAs (miRs) are endogenous non-coding RNAs that serve key functions in a wide range of biological processes, including cell growth, development, apoptosis and carcinogenesis. However, the association between miR-187 and B-cell lymphoma 6 (BCL6) has yet to be fully investigated in lymphoma cell apoptosis. The present study hypothesized that a post-translational mechanism may exist for BCL6 expression, which is regulated by miR-187 in lymphoma cells. The present study demonstrated that the expression of miR-187 in diffuse large B-cell lymphoma (DLBCL) cells was significantly decreased, and its expression was negatively correlated with BCL6 expression. It was also observed that miR-187 directly binds to the 3'-untranslated region of BCL6 mRNA and subsequently suppresses the expression of BCL6. Additionally, the induced expression of miR-187 significantly promoted DLBCL cell apoptosis in vitro. The drug sensitivity of human DLBCL SUDHL2 cells was increased following induction of miR-187 overexpression via an miR-187 mimic. In conclusion, the results of the present study suggest that the modulation of miR-187 expression in DLBCL cells may improve the sensitivity of chemotherapy through BCL6 targeting.

A Critical Role of miR-144 in Diffuse Large B-cell Lymphoma Proliferation and Invasion

MicroRNAs are endogenous noncoding RNAs that play important roles in a wide variety of biologic processes such as apoptosis, development, aging, and tumorigenesis. The B-cell lymphoma 6 (BCL6) transcriptional repressor has emerged as a critical therapeutic target in diffuse large B-cell lymphomas (DLBCL), but the mechanisms regulating BCL6 are still unclear. In the current study, we screened the microRNA expression profiles in DLBCL specimens and cell lines by qRT-PCR and found that the expression of miR-144 was significantly downregulated in DLBCL tissues and cell lines and negatively correlated with BCL6 expression. We further demonstrated that BCL6 was the direct target gene of miR-144, and miR-144 suppressed the expression of BCL6 via binding the 3'untranslated region of BCL6 mRNA. Biologically, forced expression of miR-144 significantly attenuated cell proliferation and invasion of OCI-Ly3 cells in vitro, and the tumor-suppressor effect of miR-144 was also confirmed using a xenograft mouse model in vivo Taken together, our results reveal that miR-144 regulates BCL6 in DLBCL and provide a rationale for developing strategies that target miR-144 as a therapeutic intervention for DLBCL.

Genetics of diffuse large B-cell lymphoma: paving a path to personalized medicine

Diffuse large B-cell lymphoma, the most common type of lymphoma in Western countries, remains incurable in approximately 40% of patients. Over the past decade, nascent molecular technologies have led to the discovery of many of the genetic events underlying the pathogenesis of this group of diseases. Whether by defining gene signatures that subclassify diffuse large B-cell lymphoma into subgroups, dysregulation of key cellular pathways, or specific mutations, we are approaching an era in which personalized diagnostics, prognostication, and therapy are imminent.

Absence of the first two zinc fingers in BCL6 causes the loss of inhibitory effects on cell growth

BCL6ZF is a novel transcript of BCL6, which lacks the first two zinc fingers of BCL6. It has been established that BCL6 acts as a sequence‑specific transcriptional repressor, however, the functions of BCL6ZF remain undefined. By generating stably overexpressed BCL6 and BCL6ZF in NCI‑H1299 lung cancer cells, it was found that BCL6 suppressed the levels of cell growth associated with impaired G1 phase progression compared with those of the mock control cells. However, the effects of BCL6ZF on cell growth and the cell cycle were negligible. Further study of these results demonstrated that eight genes downstream of BCL6 were markedly downregulated by the overexpression of BCL6, whereas BCL6ZF suppressed only TGFBI, indicating that the loss of the first two zinc fingers caused the loss of the inhibitory effects on cell growth and transcriptional repression. In addition, it was determined that the BCL6ZF protein was not degraded as easily as BCL6 protein by the ubiquitin/proteasome pathway, implying that the loss of the first two zinc fingers changes the three‑dimensional structure of BCL6ZF. The results demonstrated that BCL6 and BCL6ZF had different role in H1299 cells both in vitro and in vivo. The loss of its inhibitory effects on cell growth and transcriptional repressions.

Reciprocal occupancy of BCL6 and STAT5 on Growth Hormone target genes: contrasting transcriptional outcomes and promoter-specific roles of p300 and HDAC3

Expression of the Growth Hormone (GH)-stimulated gene Socs2 (Suppressor of Cytokine Signaling 2) is mediated by the transcription activator STAT5 (Signal Transducer and Activator of Transcription 5) and the transcription repressor BCL6 (B-Cell Lymphoma 6). ChIP-Sequencing identified Cish (Cytokine-Inducible SH2-containing protein) and Bcl6 as having similar patterns of reciprocal occupancy by BCL6 and STAT5 in response to GH, though GH stimulates Cish and inhibits Bcl6 expression. The co-activator p300 occupied Socs2, Cish and Bcl6 promoters, and enhanced STAT5-mediated activation of Socs2 and Cish. In contrast, on Bcl6, p300 functioned as a repressor and inhibited in conjunction with STAT5 or BCL6. The co-repressor HDAC3 (Histone deacetylase 3) inhibited the Socs2, Cish and Bcl6 promoters in the presence of STAT5. Thus transcriptional outcomes on GH-regulated genes occupied by BCL6 and STAT5 are determined in a promoter-specific fashion by co-regulatory proteins which mediate the distinction between activating and repressive transcription factors.

B-cell lymphoma 6 protein stimulates oncogenicity of human breast cancer cells

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.

Molecular dynamics analysis of the interaction between the human BCL6 BTB domain and its SMRT, NcoR and BCOR corepressors: the quest for a consensus dynamic pharmacophore

Targeting the BCL6 protein is a promising therapeutic strategy for the treatment of B cell lymphomas. One approach to treat these diseases consists of finding drug candidates able to disrupt the interactions established between BCL6 and its corepressors. Thus, this work presents a thorough comparative analysis of the interactions between the BCL6 BTB (bric-a-brac tramtrack broad complex) protein domain and its SMRT, NcoR and BCOR corepressor BBDs (BCL6 binding domain) through molecular dynamics. Moreover, a theoretical structure is presented and checked for the BCL6(BTB)-NcoR(BBD) complex. Considering the BBDs to be composed of 17 amino acids, our analyses show the region involving residues 4-15 of these 17 to play a main role in the protein-corepressor interactions. Particularly SER(11) seems to have a high relevance as it establishes specific bonds with BCL6(BTB) and is one of the only two residues sequence equivalent for the three studied corepressors. From this study, 14 pharmacophoric points have been proposed divided in two groups which coincide with residues 4-11 and 11-15, being SER(11) a hinge point. This finding suggests the possibility of searching for 2 small molecule inhibitors, mimicking 8 and 7 pharmacophoric points, respectively, which could incorporate a hydrogen donor pharmacophoric point mimicking SER(11) in any or both molecules. In short, the present work aims to contribute further knowledge in the modeling of drugs mimicking BCL6(BTB)-corepressor complexes.

Gene expression profiling of non-hodgkin lymphomas

BACKGROUND

Chromosomal translocations are genetic aberrations associated with specific non-Hodgkin lymphoma (NHL) subtypes. This study investigated the differential gene expression profile of Egyptian NHL cases based on a microarray approach.

MATERIALS AND METHODS

The study included tissue samples from 40 NHL patients and 20 normal lymph nodes used as controls. Total RNA was extracted and used for cDNA microarray assays. The quantitative real time polymerase chain reaction was used to identify the aberrantly expressed genes in cancer.

RESULTS

Significant associations of 8 up-regulated and 4 down-regulated genes with NHL were observed. Aberrant expression of a new group of genes not reported previously was apparent, including down-regulated NAG14 protein, 3 beta hydroxy-delta 5-c27 steroid oxi-reductase, oxi-glutarate dehydrogenase (lipo-amide), immunoglobulin lambda like polypeptide 3, protein kinase x linked, Hmt1, and caveolin 2 Tetra protein. The up-regulated genes were Rb binding protein 5, DKFZP586J1624 protein, protein kinase inhibitor gamma, zinc finger protein 3, choline ethanolamine phospho-transferase CEPT1, protein phosphatase, and histone deacetylase-3.

CONCLUSIONS

This study revealed that new differentially expressed genes that may be markers for NHL patients and individuals who are at high risk for cancer development.

Overexpression of the transcriptional repressor complex BCL-6/BCoR leads to nuclear aggregates distinct from classical aggresomes

Nuclear inclusions of aggregated proteins have primarily been characterized for molecules with aberrant poly-glutamine repeats and for mutated or structurally altered proteins. They were termed “nuclear aggresomes” and misfolding was shown to promote association with molecular chaperones and proteasomes. Here, we report that two components of a transcriptional repressor complex (BCL-6 and BCoR) of wildtype amino acid sequence can independently or jointly induce the formation of nuclear aggregates when overexpressed. The observation that the majority of cells rapidly downregulate BCL-6/BCoR levels, supports the notion that expression of these proteins is under tight control. The inclusions occur when BCL-6/BCoR expression exceeds 150-fold of endogenous levels. They preferentially develop in the nucleus by a gradual increase in aggregate size to form large, spheroid structures which are not associated with heat shock proteins or marked by ubiquitin. In contrast, we find the close association of BCL-6/BCoR inclusions with PML bodies and a reduction in aggregation upon the concomitant overexpression of histone deacetylases or heat shock protein 70. In summary, our data offer a perspective on nuclear aggregates distinct from classical “nuclear aggresomes”: Large complexes of spheroid structure can evolve in the nucleus without being marked by the cellular machinery for protein refolding and degradation. However, nuclear proteostasis can be restored by balancing the levels of chaperones.

BCL6 overexpression is associated with decreased p19 ARF expression and confers an independent prognosticator in gallbladder carcinoma

B cell lymphoma 6 (BCL6) is a protein that is vital for lymphogenesis. Its expression has been well established in lymphoma, especially in diffuse large B-cell lymphoma. Its role in carcinogenesis is less well understood. Previous study shows that BCL6 expression may regulate p19 functions, an important regulator for the p53 pathway. No prior study has attempted to evaluate the significance of BCL6 and p19(ARF) expression in a large cohort of patients with gallbladder carcinomas (GBCs). We selected 164 patients with GBC and performed immunostains for BCL6 and p19(ARF). BCL6 expression and p19(ARF) expression were evaluated using a histochemical score (H-score). We then correlated the results with various clinicopathological factors, disease-specific survival (DSS), and disease-free survival (DFS). BCL6 overexpression was significantly associated with high pT status, high TNM stage, higher histological grade (p = 0.029), vascular invasion, perineurial invasion, high Ki-67 labeling index, and low p19 expression. Importantly, BCL6 overexpression in GBC was strongly associated with worse DSS (p < 0.0001) and DFS (p < 0.0001) in the univariate analysis, and remained independently predictive of adverse outcomes (p = 0.001, hazard ratio (H.R.) = 3.098 for DSS; p = 0.002, H.R. = 2.255 for DFS). Low p19(ARF) expression was correlated with a poor DSS (p = 0.0144) and DFS (p = 0.0032) in the univariate analysis but was not prognosticatory in the multivariate analysis. In GBC, BCL6 overexpression correlated with adverse phenotypes and decreased p19(ARF) expression. BCL6 overexpression also independently predicts worse DSS and DFS, suggesting it has a role in tumorigenesis or carcinogenesis and could be a potential prognostic indicator in GBC.

Hepatic genotoxicity and toxicogenomic responses in Muta™Mouse males treated with dibenz[a,h]anthracene

Dibenz[a,h]anthracene (DB[a,h]A) is a polycyclic aromatic hydrocarbon that is a by-product of combustion and a potent carcinogen. Few studies have investigated the effects of DB[a,h]A on mRNA and microRNA expression to dissect the mechanisms involved in carcinogenesis. In this study, mature male mice (Muta(™)Mouse) were exposed to 6.25, 12.5 and 25mg/kg/day DB[a,h]A by oral gavage for 28 consecutive days. Results were compared with mice similarly exposed to benzo[a]pyrene (B[a]P) in our previous work. Liver DNA adduct levels and lacZ mutant frequency increased dose dependently for both chemicals. Aryl hydrocarbon receptor (AhR) potency was greater for DB[a,h]A than B[a]P using the chemical-activated luciferase expression assay. Microarray analysis revealed 19 up-regulated and 22 down-regulated genes (false discovery rate-adjusted P ≤ 0.05; fold change ≥ 1.5) following treatment with 6.25 mg/kg/day DB[a,h]A. Thirteen transcripts were up-regulated and 32 down-regulated in the 12.5mg/kg/day group. The 25mg/kg/day dose had major effects on mRNA expression with 135 up-regulated and 104 down-regulated genes. Overall, perturbations were greater for DB[a,h]A than for B[a]P; in vitro chemical-activated luciferase expression supports that this may be driven by the AhR. Many of the DB[a,h]A-affected genes are implicated in cancer and are essential in vital biological functions including circadian rhythm, glucose metabolism, lipid metabolism, immune response, cell cycle and apoptosis. Although a number of functional groups were similarly affected by B[a]P and DB[a,h]A, in general the responses generated by each chemical were quite distinct. Commonalities included a DNA damage response leading to induction of cell cycle arrest and apoptosis in both Tp53-dependent and Tp53-independent manners. MicroRNA expression was identical for both chemicals, with only miR-34a showing a dose-dependent increase in treated mice.

Genome-wide association study of B cell non-Hodgkin lymphoma identifies 3q27 as a susceptibility locus in the Chinese population

To identify genetic risk factors underlying non-Hodgkin lymphomas (NHLs) from the B cell lineage, we conducted a genome-wide association study (GWAS) of 253 Chinese individuals with B cell NHL (cases) and 1,438 controls and further validation in 1,175 cases and 5,492 controls. We identified a new susceptibility locus, rs6773854, located between BCL6 (encoding B cell lymphoma protein 6) and LPP (encoding lipoma preferred partner) on oncogene-rich chromosome 3q27 that was significantly associated with increased risk of B cell NHL (meta-analysis P = 3.36 × 10⁻¹³, per-allele odds ratio (OR) = 1.44) and with diffuse large B cell lymphoma (DLBCL) in particular (meta-analysis P = 1.14 × 10⁻¹¹, OR = 1.47). We found no evidence of association of rs6773854 with non-B cell NHLs (T cell and natural killer (NK) lineages) (P = 0.17, OR = 1.12) and observed significant heterogeneity between B cell and non-B cell subtypes (Phet = 0.01, I² = 84%). Our results provide insight that germline variation in the intergenic region between BCL6 and LPP has a role in risk of B cell lymphomagenesis.

Enhanced susceptibility to Citrobacter rodentium infection in microRNA-155-deficient mice

MicroRNAs (miRNAs) are small noncoding molecules that control gene expression posttranscriptionally, with microRNA-155 (miR-155) one of the first to be implicated in immune regulation. Here, we show that miR-155-deficient mice are less able to eradicate a mucosal Citrobacter rodentium infection than wild-type C57BL/6 mice. miR-155-deficient mice exhibited prolonged colonization associated with a higher C. rodentium burden in gastrointestinal tissue and spread into systemic tissues. Germinal center formation and humoral immune responses against C. rodentium were severely impaired in infected miR-155-deficient mice. A similarly susceptible phenotype was observed in μMT mice reconstituted with miR-155-deficient B cells, indicating that miR-155 is required intrinsically for mediating protection against this predominantly luminal bacterial pathogen.

Cytogenetics and molecular cytogenetics in diffuse large B-cell lymphoma (DLBCL)

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) accounts for up to 40% of all non-Hodgkin's lymphomas diagnosed in the western hemisphere. Determination of the gene expression profile has confirmed the physiological heterogeneity of the disease and defined three molecular prognostic subgroups - germinal center B-cell-like (GCB), activated B-cell-like (ABC) and primary mediastinal B-cell lymphoma (PMBL) - with different gene expression and prognosis.

METHODS AND RESULTS

This review covers current knowledge on the most frequent recurrent cytogenetic and molecular cytogenetic aberrations in molecular DLBCL subgroups.

CONCLUSIONS

Cytogenetic and molecular cytogenetic techniques used to determine nonrandom chromosomal aberrations in patients with DLBCL have revealed the incidence of frequent cytogenetic aberrations in the subgroups reported, suggesting their potential use for more accurate prognostic stratification of DLBCL, contributing to personalized selection of the most effective therapy.

Ron receptor-dependent gene regulation in a mouse model of endotoxin-induced acute liver failure

BACKGROUND

Prior experimentation has shown that loss of the tyrosine kinase (TK) signaling domain of the Ron receptor leads to marked hepatocyte protection in a model of lipopolysaccharide-induced acute liver failure (ALF) in D-galactosamine (GalN)-sensitized mice. The aim of this study was to identify the role of Ron in the regulation of hepatic gene expression.

METHODS

Microarray analyses were performed on liver RNA isolated sequentially from wild-type (WT) and TK-/- mice during the progression of ALF. Gene array data were validated using Western and immunohistochemistry analyses as well as with ex vivo culture systems.

RESULTS

At baseline, 101 genes were differentially expressed between WT and TK-/- livers, which regulate processes involved in hypoxia, proliferation, apoptosis and metabolism. One hour after ALF induction, WT livers exhibited increased cytokine expression compared to TK-/- livers, and after 4 hours, an induction of suppressor of cytokine signaling (SOCS) genes as well as JAK-STAT pathway activation were prominent in TK-/- livers compared to controls.

CONCLUSION

Our studies suggest a novel hepato-protective mechanism in Ron TK-/- mice wherein increased and sustained SOCS production and JAK-STAT activation in the hepatocyte may inhibit the destructive proinflammatory milieu and promote survival factors which blunt hepatic death and the ensuing development of ALF.

The impact of CDK inhibition in human malignancies associated with pronounced defects in apoptosis: advantages of multi-targeting small molecules

Malignant cells in chronic lymphocytic leukemia (CLL) and related diseases are heterogeneous and consist primarily of long-lived resting cells in the periphery and a minor subset of dividing cells in proliferating centers. Both cell populations have different molecular signatures that play a major role in determining their sensitivity to therapy. Contemporary approaches to treating CLL are heavily reliant on cytotoxic chemotherapeutics. However, none of the current treatment regimens can be considered curative. Pharmacological CDK inhibitors have extended the repertoire of potential drugs for CLL. Multi-targeted CDK inhibitors affect CDKs involved in regulating both cell cycle progression and transcription. Their interference with transcriptional elongation represses anti-apoptotic proteins and, thus, promotes the induction of apoptosis. Importantly, there is evidence that treatment with CDK inhibitors can overcome resistance to therapy. The pharmacological CDK inhibitors have great potential for use in combination with other therapeutics and represent promising tools for the development of new curative treatments for CLL.

Bcl6 is expressed in neuroblastoma: tumor cell type-specific expression predicts outcome

Neuroblastoma (NB) is the most common extracranial solid neoplasm of infancy and childhood. Whereas most low-risk patients do well, children with high-risk tumors often fail intensive treatment. Identification of novel biomarkers is critical to improve prognostication, tailor therapy, and develop new therapeutic targets. Differential RNA-level expression between tumor cells with neuroblastic (N-type) and Schwannian stromal (S-type) phenotypes was used to identify genes of potential interest based on tumor cell type-specific regulation. Gene expression microarray analysis revealed marked differences between N-type and S-type cells in their levels of BCL6 messenger RNA, a transcriptional regulator overexpressed in a variety of hematopoietic malignancies. S-type cells express higher levels of Bcl6 RNA and protein than N-type, and protein levels are significantly limited by proteasome function. An NB tumor tissue microarray linked to clinicopathologic data was immunohistochemically stained to measure Bcl6 protein levels. Bcl6 was detected in both the neuroblastic and Schwannian stromal regions, as distinguished histologically, and correlated with outcome. We found that expression in neuroblastic regions differentiates outcomes, in that Bcl6 expression in neuroblastic regions is associated with increased time to relapse and increased overall survival compared with absent expression in neuroblastic regions, regardless of Schwannian stromal expression. Thus, our findings suggest that Bcl6 may be useful as a prognostic marker and might represent a potential therapeutic target for high-risk NB.

BCL-6 expression in mesenchymal tumours: an immunohistochemical and fluorescence in situ hybridisation study

The BCL-6 proto-oncogene encodes a transcriptional repressor protein. Among normal tissues, BCL-6 expression is confined to germinal center B-cells and a subpopulation of T-helper cells. Little is known about BCL-6 expression in mesenchymal tissues. We examined a series of solitary fibrous tumor (SFT) and other mesenchymal tumors for BCL-6 expression. Immunohistochemistry for BCL-6 was performed on 64 mesenchymal tumors [26 SFT (19 benign/uncertain, 7 malignant), 6 synovial sarcomas (SS), 5 gastrointestinal stromal tumors (GIST), 5 malignant peripheral nerve sheath tumors (MPNST), 5 leiomyosarcomas (LMS), 9 leiomyomas (LM) 4 desmoid tumors (DT), 4 perineuriomas (PN)]. Nuclear immunoreactivity was considered positive. Six BCL-6 positive SFT were also tested for BCL-6 gene rearrangement/amplification by FISH. Nuclear expression of BCL-6 was seen in 13/26 SFT, 5/5 LMS, 1/9 LM, 5/6 SS, 1/5 GIST, 1/5 MPNST, 1/4 PN, and 0/5 DT. BCL-6 expression was significantly more frequent in malignant (6/7) as compared with benign/uncertain SFT (6/19) (p=0.02) and in LMS (5/5) as compared with LM (1/9) (p=0.003). FISH for BCL-6 rearrangement/amplification was negative in all tested cases. We have observed BCL-6 expression in 50% or more of SFT, SS, and LMS, and in a lesser percentage of LM, GIST, MPNST and PN. Significantly more frequent expression of BCL-6 in malignant compared with benign/uncertain SFT and in LMS compared with LM suggests abnormalities in the BCL-6 signaling pathway may contribute to malignant transformation in at least some mesenchymal tumors. It is unlikely that BCL-6 expression in mesenchymal tumors is due to BCL-6 gene amplification or rearrangement.

Association of JAK-STAT pathway related genes with lymphoma risk: results of a European case-control study (EpiLymph)

Previous studies have suggested an important role for the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signalling pathway in tumour development. Therefore, we explored genetic variants in JAK-STAT pathway associated genes with lymphoma risk. In samples of the EpiLymph case-control study we genotyped 1536 single nucleotide polymorphisms (SNPs) using GoldenGate BeadArray™ Technology (Illumina, San Diego, CA, USA). Here, we report the associations between selected SNPs and haplotypes of the JAK-STAT pathway and risk of Hodgkin lymphoma (HL), B-cell non-Hodgkin lymphoma (B-NHL) and most frequent B-NHL subtypes. Among 210 relevant JAK-STAT pathway-related SNPs, polymorphisms in nine genes (BMF, IFNG, IL12A, SOCS1, STAT1, STAT3, STAT5A, STAT6, TP63) were significantly associated with lymphoma risk. At a study-wise significance level, we obtained a risk reduction of 28% among carriers of the heterozygous genotype of the STAT3 variant (rs1053023) for B-NHL. For six other variants within the STAT3 gene we observed an inverse association with different lymphoma subtypes. A reduced risk for HL was observed for the heterozygous genotype of the STAT6 SNP (rs324011). This is an explorative investigation to examine associations between JAK-STAT signalling related genes and lymphoma risk. The results implicate a relevant role of certain pathway-related genes in lymphomagenesis, but still need to be approved by independent studies.

Proapoptotic signaling activity of the anti-CD40 monoclonal antibody dacetuzumab circumvents multiple oncogenic transformation events and chemosensitizes NHL cells

Non-Hodgkin lymphoma (NHL) is a genetically heterogeneous disease with several oncogenic events implicated in the transformation of normal developing B lymphocytes. The objective of this study was to elucidate the signal transduction-based antitumor mechanism(s) of action for the anti-CD40 monoclonal antibody dacetuzumab (SGN-40) in NHL. We report that dacetuzumab activates two distinct proapoptotic signaling pathways, overcoming transformation events key to the pathogenesis of NHL. Dacetuzumab-mediated CD40 signaling constitutively activated the nuclear factor-κB and mitogen-activated protein kinase signaling pathways producing the sustained downregulation of B-cell lymphoma 6 (BCL-6), an oncoprotein implicated in lymphomagenesis. Loss of BCL-6 resulted in c-Myc downregulation and activation of a transcriptional program characteristic of early B-cell maturation, concomitant with reduced proliferation and cell death. In a second mechanism, dacetuzumab signaling induced the expression of the proapoptotic p53 family member TAp63α and downstream proteins associated with the intrinsic and extrinsic apoptotic machinery. Dacetuzumab was synergistic in combination with DNA-damaging chemotherapeutic drugs, correlating with TAp63α upregulation. Furthermore, dacetuzumab augmented the activity of rituximab in combination with multiple chemotherapies in the xenograft models of NHL. The ability of dacetuzumab signaling to circumvent oncogenic events and potentiate the activity of chemotherapy regimens provides a unique therapeutic approach to NHL.

The basis and rational use of molecular genetic testing in mature B-cell lymphomas

An increasing number of neoplasms are associated with variably specific genetic abnormalities. This is best exemplified by hematological malignancies, in which there is a growing list of entities that are defined by their genetic lesion(s); this is not (yet) the case in mature B-cell lymphomas. However, enhanced insights into the pathogenesis of this large and diverse group of lymphomas have emerged with the ongoing unraveling of a plethora of fascinating genetic abnormalities. The purpose of this review is to synthesize well-recognized data and nascent discoveries in our understanding of the genetic basis of a spectrum of mature B-cell lymphomas, and how this may be applied to contemporary clinical practice. Despite the explosion of new and exciting knowledge in this arena, with the potential for enhanced diagnostic and prognostic strategies, it is essential to remain cognizant of the limitations (and complexity) of genetic investigations, so that assays can be developed and used both judiciously and rationally.

Anticancer therapy SMRT-ens up: targeting the BCL6-SMRT interaction in B cell lymphoma

Transcription factors have proven to be difficult targets for the development of small-molecule drugs. In this issue of Cancer Cell, Cerchietti et al. identify and characterize a specific, small-molecule inhibitor of BCL6, an oncogenic transcriptional repressor, that has high clinical promise for treating diffuse large B cell lymphoma.

Effectors and memories: Bcl-6 and Blimp-1 in T and B lymphocyte differentiation

Bcl-6 and Blimp-1 have recently been identified as key transcriptional regulators of effector and memory differentiation in CD4(+) T cells and CD8(+) T cells. Bcl-6 and Blimp-1 were previously known to be critical regulators of effector and memory differentiation of B lymphocytes. The new findings unexpectedly point to the Bcl-6 and Blimp-1 regulatory axis as a ubiquitous mechanism for controlling effector and memory lymphocyte differentiation and function. Bcl-6 and Blimp-1 are antagonistic transcription factors and can function as a self-reinforcing genetic switch for cell-fate decisions. However, their influences in different lymphocytes are complex. Here we review and examine the commonalities and differences in the functions of these transcription factors in CD4(+) follicular helper T(FH) lymphocytes, effector CD8(+) T lymphocytes and B lymphocytes.

Diverse hematological malignancies including hodgkin-like lymphomas develop in chimeric MHC class II transgenic mice

A chimeric HLA-DR4-H2-E (DR4) homozygous transgenic mouse line spontaneously develops diverse hematological malignancies with high frequency (70%). The majority of malignancies were distributed equally between T and B cell neoplasms and included lymphoblastic T cell lymphoma (LTCL), lymphoblastic B cell lymphoma (LBCL), diffuse large B cell lymphoma (DLBCL), the histiocyte/T cell rich variant of DLBCL (DLBCL-HA/T cell rich DLBCL), splenic marginal zone lymphoma (SMZL), follicular B cell lymphoma (FBL) and plasmacytoma (PCT). Most of these neoplasms were highly similar to human diseases. Also, some non-lymphoid malignancies such as acute myeloid leukemia (AML) and histiocytic sarcoma were found. Interestingly, composite lymphomas, including Hodgkin-like lymphomas, were also detected that had CD30(+) Hodgkin/Reed-Sternberg (H/RS)-like cells, representing a tumor type not previously described in mice. Analysis of microdissected H/RS-like cells revealed their origin as germinal center B cells bearing somatic hypermutations and, in some instances, crippled mutations, as described for human Hodgkin lymphoma (HL). Transgene integration in an oncogene was excluded as an exclusive driving force of tumorigenesis and age-related lymphoma development suggests a multi-step process. Thus, this DR4 line is a useful model to investigate common molecular mechanisms that may contribute to important neoplastic diseases in man.