BCL6 degradation caused by the interaction with the C-terminus of pro-HB-EGF induces cyclin D2 expression in gastric cancers

Pharmaceutical inhibition of BCL6 ameliorates resistance to imatinib in chronic myeloid leukemia

The tyrosine kinase inhibitors (TKIs) have improved overall survival of CML (chronic myeloid leukemia) patients and allow them to experience normal life expectancy. However, relapse and drug resistance remain the main challenges in the clinical treatment of CML. The B-cell lymphoma 6 (BCL6) is essential to regulation of multiple function such as immune response and lymphomagenesis in lymph node germinal cells. Recent studies have shown that BCL6 is required for the maintenance of leukemia stem cells in CML, but the expression of Bcl-6 in response to Imatinib and the underlying mechanism are still unclear. Here, we found that BCL6 is expressed at high levels in primary CML bone marrow samples and CML TKI-resistance cell lines. CML cells with higher levels of BCL6 were generally sensitive to treatment with BCL6 inhibitors, BI-3812. Treatment of CML cells with BCL6 inhibitor and TKIs suggested enhanced anti-leukemia activity. In summary, our findings suggest BCL6 as a therapeutic target for the treatment of CML.

Patterns of Oncogene Coexpression at Single-Cell Resolution Influence Survival in Lymphoma

Cancers often overexpress multiple clinically relevant oncogenes, but it is not known if combinations of oncogenes in cellular subpopulations within a cancer influence clinical outcomes. Using quantitative multispectral imaging of the prognostically relevant oncogenes MYC, BCL2, and BCL6 in diffuse large B-cell lymphoma (DLBCL), we show that the percentage of cells with a unique combination MYC+BCL2+BCL6- (M+2+6-) consistently predicts survival across four independent cohorts (n = 449), an effect not observed with other combinations including M+2+6+. We show that the M+2+6- percentage can be mathematically derived from quantitative measurements of the individual oncogenes and correlates with survival in IHC (n = 316) and gene expression (n = 2,521) datasets. Comparative bulk/single-cell transcriptomic analyses of DLBCL samples and MYC/BCL2/BCL6-transformed primary B cells identify molecular features, including cyclin D2 and PI3K/AKT as candidate regulators of M+2+6- unfavorable biology. Similar analyses evaluating oncogenic combinations at single-cell resolution in other cancers may facilitate an understanding of cancer evolution and therapy resistance.

SIGNIFICANCE

Using single-cell-resolved multiplexed imaging, we show that selected subpopulations of cells expressing specific combinations of oncogenes influence clinical outcomes in lymphoma. We describe a probabilistic metric for the estimation of cellular oncogenic coexpression from IHC or bulk transcriptomes, with possible implications for prognostication and therapeutic target discovery in cancer. This article is highlighted in the In This Issue feature, p. 1027.

The malignancy suppression and ferroptosis facilitation of BCL6 in gastric cancer mediated by FZD7 repression are strengthened by RNF180/RhoC pathway

BACKGROUND

B-cell lymphoma 6 (BCL6) is a transcription repressor that plays a tumor suppressor or promoting role in various tumors. However, its function and molecular mechanism in gastric cancer (GC) remain unclear. Ferroptosis, a novel programmed cell death, is closely related to tumor development. In this research, we aimed to explore the role and mechanism of BCL6 in malignant progression and ferroptosis of gastric cancer.

METHODS

Firstly, BCL6 was identified as an important biomarker that attenuated the proliferation and metastasis of GC through tumor microarrays and confirmed in GC cell lines. RNA sequence was performed to explore the downstream genes of BCL6. The underlying mechanisms were further investigated by ChIP, dual luciferase reporter assays and rescue experiments. Cell death, lipid peroxidation, MDA and Fe²⁺ level were detected to determine the effect of BCL6 on ferroptosis and the mechanism was revealed. CHX, MG132 treatment and rescue experiments were used to explore the upstream regulatory mechanism of BCL6.

RESULTS

Here we showed that BCL6 expression was significantly decreased in GC tissues, and patients with low BCL6 expression showed more malignant clinical features and poor prognosis. The upregulation of BCL6 may significantly inhibited the proliferation and metastasis of GC cells in vitro and in vivo. In addition, we found that BCL6 directly binds and transcriptionally represses Wnt receptor Frizzled 7 (FZD7) to inhibit the proliferation, metastasis of GC cells. We also found that BCL6 promoted lipid peroxidation, MDA and Fe²⁺ level to facilitate ferroptosis of GC cells by FZD7/β-catenin/TP63/GPX4 pathway. Furthermore, the expression and function of BCL6 in GC were regulated by the ring finger protein 180 (RNF180)/ras homolog gene family member C (RhoC) pathway, which had been elucidated to be involved in significantly mediating the proliferation and metastasis of GC cells.

CONCLUSIONS

In summary, BCL6 should be considered a potential intermediate tumor suppressor to inhibit the malignant progression and induce ferroptosis, which might be a promising molecular biomarker for further mechanistic investigation of GC.

B-cell Lymphoma 6 Inhibitors: Current Advances and Prospects of Drug Development for Diffuse Large B-cell Lymphomas

B-cell lymphoma 6 (BCL6) is a transcriptional repressor that regulates the differentiation of B lymphocytes and mediates the formation of germinal centers (GCs) by recruiting corepressors through the BTB domain of BCL6. Physiological processes regulated by BCL6 involve cell activation, differentiation, DNA damage, and apoptosis. BCL6 is highly expressed when the gene is mutated, leading to the malignant proliferation of cells and drives tumorigenesis. BCL6 overexpression is closely correlated with tumorigenesis in diffuse large B-cell lymphoma (DLBCL) and other lymphomas, and BCL6 inhibitors can effectively inhibit some lymphomas and overcome resistance. Therefore, targeting BCL6 might be a promising therapeutic strategy for treating lymphomas. Herein, we comprehensively review the latest development of BCL6 inhibitors in diffuse large B-cell lymphoma and discuss the overview of the pharmacophores of BCL6 inhibitors and their efficacies in vitro and in vivo. Additionally, the current advances in BCL6 degraders are provided.

BCL6, a key oncogene, in the placenta, pre-eclampsia and endometriosis

BACKGROUND

The key oncogene B-cell lymphoma 6 (BCL6) drives malignant progression by promoting proliferation, overriding DNA damage checkpoints and blocking cell terminal differentiation. However, its functions in the placenta and the endometrium remain to be defined.

OBJECTIVE AND RATIONALE

Recent studies provide evidence that BCL6 may play various roles in the human placenta and the endometrium. Deregulated BCL6 might be related to the pathogenesis of pre-eclampsia (PE) as well as endometriosis. In this narrative review, we aimed to summarize the current knowledge regarding the pathophysiological role of BCL6 in these two reproductive organs, discuss related molecular mechanisms, and underline associated research perspectives.

SEARCH METHODS

We conducted a comprehensive literature search using PubMed for human, animal and cellular studies published until October 2021 in the following areas: BCL6 in the placenta, in PE and in endometriosis, in combination with its functions in proliferation, fusion, migration, invasion, differentiation, stem/progenitor cell maintenance and lineage commitment.

OUTCOMES

The data demonstrate that BCL6 is important in cell proliferation, survival, differentiation, migration and invasion of trophoblastic cells. BCL6 may have critical roles in stem/progenitor cell survival and differentiation in the placenta and the endometrium. BCL6 is aberrantly upregulated in pre-eclamptic placentas and endometriotic lesions through various mechanisms, including changes in gene transcription and mRNA translation as well as post-transcriptional/translational modifications. Importantly, increased endometrial BCL6 is considered to be a non-invasive diagnostic marker for endometriosis and a predictor for poor outcomes of IVF. These data highlight that BCL6 is crucial for placental development and endometrium homeostasis, and its upregulation is associated with the pathogenesis of PE, endometriosis and infertility.

WIDER IMPLICATIONS

The lesson learned from studies of the key oncogene BCL6 reinforces the notion that numerous signaling pathways and regulators are shared by tumors and reproductive organs. Their alteration may promote the progression of malignancies as well as the development of gestational and reproductive disorders.

Microglial-stimulation of glioma invasion involves the EGFR ligand amphiregulin

High grade glioma is one of the deadliest human cancers with a median survival rate of only one year following diagnosis. The highly motile and invasive nature of high grade glioma makes it difficult to completely remove surgically. Therefore, increasing our knowledge of the mechanisms glioma cells use to invade normal brain is of critical importance in designing novel therapies. It was previously shown by our laboratory that tumor-associated microglia (TAMs) stimulate glioma cell invasion and this process is dependent on CSF-1R signaling. In this study, we seek to identify pro-invasive factors that are upregulated in microglia in a CSF-1R-dependent manner. We assayed cDNA and protein from microglia treated with conditioned media from the murine glioma cell line GL261, and discovered that several EGFR ligands including amphiregulin (AREG) are strongly upregulated. This upregulation is blocked by addition of a pharmacological CSF-1R inhibitor. Using RNA interference, we show that AREG-depleted microglia are less effective at promoting invasion of GL261 cells into Matrigel-coated invasion chambers. In addition, an AREG blocking antibody strongly attenuates the ability of THP-1 macrophages to activate human glioma cell line U87 invasion. Furthermore, we have identified a signaling pathway which involves CSF-1 signaling through ERK to upregulate AREG expression in microglia. Interfering with ERK using pharmacological inhibitors prevents AREG upregulation in microglia and microglia-stimulated GL261 invasion. These data highlight AREG as a key factor in produced by tumor associated microglia in promoting glioma invasion.

LINC00152 Promotes Tumor Progression and Predicts Poor Prognosis by Stabilizing BCL6 From Degradation in the Epithelial Ovarian Cancer

Long non-coding RNA 00152 (LINC00152) is tumorigenic in multiple somatic malignancies. However, its prognostic significance and molecular mechanisms in the epithelial ovarian cancer (EOC) remain elusive. Here our study reveals that dysregulation of LINC00152 is a predictor of poor prognosis in patients with EOC and facilitates ovarian tumor growth and metastasis both in vitro and in vivo; the expression of LINC00152 positively correlates with the protein levels of BCL6 in EOC tissues and ovarian tumor cells; LINC00152 binds to Ser333 and Ser343 of BCL6 protein and stabilizes BCL6 from poly-ubiquitination thus facilitating the oncogenic functions in EOC. Moreover, overexpression of the mutant BCL6^S333A/S343A fails to rescue the reduced proliferation and invasion caused by the knockdown of endogenous BCL6 in LINC00152-overexpressing cells. Our study might not only offer clues to the network of lncRNA-protein interactions but also provide potential therapeutic targets for the tumor pharmacology.

T follicular helper and T follicular regulatory cells in colorectal cancer: A complex interplay

Colorectal cancer is considered to be one of the major causes of morbidity and mortality all over the world. T Follicular helper (T_FH) and T follicular regulatory (T_FR) cells are specialized providers of T-cells to help B-cells and shaping germinal centers (GC) response. Recent researches reported a high percentage of T_FH and T_FR in different infectious diseases and certain malignancies. However, their functional role in human colorectal cancer (CRC) is relatively unknown. Furthermore, recent studies show that the interaction of both T_FH cells and T_FR cells are essential to promote several diseases. Under the control of specific cytokines and B-cell lymphoma 6 transcription factor (Bcl-6), the major transcription factor of T_FH cells, T_FH, can expand to the other distinct CD4 + T helper cells (TH1, TH2, and TH17) which exert a different role in the development of CRC. This review aims to discuss these suggested roles of the two-opposite subset of follicular T cells in colorectal cancer immune pathogenesis.

HB-EGF Synthesized by CD4 T Cells Modulates Allergic Airway Eosinophilia by Regulating IL-5 Synthesis

CD4 T cells express the epidermal growth factor (EGF) receptor ligand, heparin-binding EGF (HB-EGF), with no defined immuno-pathophysiological function. Therefore, we wished to elucidate the function of HB-EGF synthesized by CD4 T cells in the context of allergic pulmonary inflammation and the asthma surrogate, airway hyperresponsiveness, in a murine acute model of asthma. In this study, we show how knocking out HB-EGF expression in CD4 T cells in vivo attenuates IL-5 synthesis in the lung that is accompanied by diminished eosinophilic inflammation and airway hyperresponsiveness. HB-EGF coimmunoprecipitates with the transcriptional repressor B cell lymphoma 6 (Bcl-6) in CD4 T cells. Knocking out HB-EGF in CD4 T cells resulted in increased Bcl-6 binding to the IL-5 gene and decreased IL-5 mRNA expression. Thus, these findings suggest an immunoregulatory function for intrinsic HB-EGF expressed by CD4 T cells in T_H2 inflammation and airway dysfunction by modulating IL-5 expression via binding to and inhibiting the repressive function of Bcl-6.

Knockdown of BCL6 Inhibited Malignant Phenotype and Enhanced Sensitivity of Glioblastoma Cells to TMZ through AKT Pathway

Background

BCL6 was a critical prooncogene of human B-cell lymphomas which promoted tumor progress and contributed to malignant behavior in several kinds of cancers. This study was to detect the expression of BCL6 and its biological effect on glioma.

Methods

RT-PCR and Western blot were used to detect the expression of BCL6 mRNA and protein in tissues and glioblastoma cell lines. The expression of BCL6 was knockdown in two glioblastoma cell lines (U87 and U251) using BCL6 shRNA. The CCK8, colony-formation, flow cytometry, Transwell, and wound-healing assays were used to evaluate the malignant phenotypic change of glioblastoma cells.

Results

The expression of BCL6 was higher in glioma tissues and glioblastoma cell lines than normal tissues. Knockdown of BCL6 expression reduced the proliferation, migration, and invasion of glioblastoma cells. Moreover, knockdown of BCL6 changed expression of proteins related to malignant behaviors of glioblastoma cells. The suppression of BCL6 could increase chemosensitivity of U87 and U251 to temozolomide. Downregulation of BCL6 levels suppressed the expression of BCL2, cyclin D1, MMP2, and MMP9 proteins as well as two classic signaling pathway proteins p-AKT and p-ERK. Simultaneously, BAX and p21 protein levels were upregulated along with knockdown of BCL6.

Conclusions

Our results indicated that BCL6 may be a tumor oncogene involved in the progression of glioma via affecting AKT and MAPK signaling pathways.

Epstein-Barr Virus Nuclear Antigen 3C Facilitates Cell Proliferation by Regulating Cyclin D2

Cell cycle regulation is one of the hallmarks of virus-mediated oncogenesis. Epstein-Barr virus (EBV)-induced lymphomas express a repertoire of essential viral latent proteins that regulate expression of cell cycle-related proteins to dysregulate this process, thereby facilitating the proliferation of infected cells. We now demonstrate that the essential EBV latent protein 3C (EBNA3C) stabilizes cyclin D2 to regulate cell cycle progression. More specifically, EBNA3C directly binds to cyclin D2 and they colocalize together in nuclear compartments. We show that EBNA3C regulates the promoter of cyclin D2 through cooperation with master transcription factor Bcl6 and enhances its stability by inhibiting its ubiquitin-dependent degradation. EBNA3C also promoted cell proliferation in the presence of cyclin D2, suggesting that cyclin D2 contributes to EBNA3C-mediated cell cycle progression. These results provide new clues as to the role of this essential viral latent protein and its ability to regulate expression of cellular factors, which drives the oncogenic process.IMPORTANCE Epstein-Barr virus (EBV) is the first identified human tumor virus and is associated with a range of human cancers. During EBV-induced lymphomas, the essential viral latent proteins modify the expression of cell cycle-related proteins to disturb the cell cycle process, thereby facilitating the proliferative process. The essential EBV nuclear antigen 3C (EBNA3C) plays an important role in EBV-mediated B-cell transformation. Here we show that EBNA3C stabilizes cyclin D2 to regulate cell cycle progression. More specifically, EBNA3C directly binds to cyclin D2, and they colocalize together in nuclear compartments. EBNA3C enhances cyclin D2 stability by inhibiting its ubiquitin-dependent degradation and significantly promotes cell proliferation in the presence of cyclin D2. Our results provide novel insights into the function of EBNA3C on cell progression by regulating the cyclin D2 protein and raise the possibility of the development of new anticancer therapies against EBV-associated cancers.

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.

Influence of the HER receptor ligand system on sensitivity to cetuximab and trastuzumab in gastric cancer cell lines

Purpose

Gastric cancer remains a major health concern, and improvement of the therapeutic options is crucial. Treatment with targeted therapeutics such as the EGFR-targeting antibody cetuximab or the HER2-targeting antibody trastuzumab is either ineffective or moderately effective in this disease, respectively. In this study, we analysed the involvement of the HER receptor ligands amphiregulin (AREG), epidermal growth factor (EGF), heparin-binding epidermal growth factor (HB-EGF) and transforming growth factor alpha (TGFα) in the responsiveness of gastric cancer cell lines to cetuximab and trastuzumab.

Methods

A panel of 11 gastric cancer cell lines was characterized for cetuximab and trastuzumab sensitivity, ligand secretion and expression and activation of the HER receptors using WST-1 cell proliferation assays, ELISAs and Western blot analyses. We further investigated the effects of an exogenous ligand application on the cetuximab and trastuzumab sensitivity.

Results

We found no correlation between TGFα secretion and the sensitivity to cetuximab or trastuzumab. For AREG, we confirmed previous results indicating that this ligand is a positive predictor of cetuximab sensitivity. Exogenous HB-EGF was effective in rescuing sensitive cell lines from inhibition of cell proliferation by both, cetuximab and trastuzumab.

Conclusions

Our data indicate that HB-EGF may be a useful marker for the prediction of trastuzumab sensitivity in gastric cancer.

Electronic supplementary material

The online version of this article (doi:10.1007/s00432-016-2308-z) contains supplementary material, which is available to authorized users.

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.

Membrane-Tethered Intracellular Domain of Amphiregulin Promotes Keratinocyte Proliferation

The epidermal growth factor receptor (EGFR) and its ligands are essential regulators of epithelial biology, which are often amplified in cancer cells. We have previously shown that shRNA-mediated silencing of one of these ligands, amphiregulin (AREG), results in keratinocyte growth arrest that cannot be rescued by soluble extracellular EGFR ligands. To further explore the functional importance of specific AREG domains, we stably transduced keratinocytes expressing tetracycline-inducible AREG-targeted shRNA with lentiviruses expressing silencing-proof, membrane-tethered AREG cytoplasmic and extracellular domains (AREG-CTD and AREG-ECD), as well as full-length AREG precursor (proAREG). Here we show that growth arrest of AREG-silenced keratinocytes occurs in G2/M and is significantly restored by proAREG and AREG-CTD but not by AREG-ECD. Moreover, the AREG-CTD was sufficient to normalize cell cycle distribution profiles and expression of mitosis-related genes. Our findings uncover an important role of the AREG-CTD in regulating cell division, which may be relevant to tumor resistance to EGFR-directed therapies.

Overexpression of miR-155 promotes the proliferation and invasion of oral squamous carcinoma cells by regulating BCL6/cyclin D2

Although microRNA-155 (miR-155) is known to play an important role in many cancers, its expression and function in oral squamous cell carcinoma (OSCC) was not fully understood. Thus, in the present study, we investigated the expression of miR-155 and also the role this miR plays in OSCC. We used the OSCC cell line (CAL27) and paired tumor and non-tumor tissue samples from patients with OSCC in order to detect the expression of miR-155. Cell proliferation, migration and invasion assays were then undertaken in order to determine the effect of miR-155 on the biological behavior of CAL27 cells following transient transfection with miR-155 mimic and antagomir. The regulatory effect of miR-155 on its target gene B-cell CLL/lymphoma 6 (BCL6) and downstream gene cyclin D2 (CCND2) was also analyzed. We found that miR-155 expression in OSCC cell and tumor tissues was significantly higher than that of the controls. We noted that the miR-155 mimic enhanced CAL27 cell proliferation, migration and invasion ability, downregulated BCL6 levels, and increased cyclin D2 expression. However, we noted that abrogating miR-155 with the miR-155 antagomir suppressed CAL27 cell proliferation, migration and invasion, upregulated BCL6 and reduced cyclin D2 expression. These results indicate that miR-155 plays a tumor-promoting role in OSCC by regulating the BCL6/cyclin D2 axis.

Up regulation of the long non-coding RNA NEAT1 promotes esophageal squamous cell carcinoma cell progression and correlates with poor prognosis

Dysregulation of NEAT1 plays critical oncogenic roles and facilitates tumorigenesis on various human tumor entities. However, little information is available about the expression pattern of NEAT1 in esophageal squamous cell carcinoma (ESCC). The contributions of this lncRNA to tumorigenesis and progression of ESCC aslo remains unclear. By performing quantitative real-time polymerase chain reaction (qRT-PCR) in 96 cases of ESCC, we found that the expression of NEAT1 was higher in ESCC tissues and cells compared with the normal counterparts. Pearson analysis showed that elevated NEAT1 levels were extraordinarily correlated with the tumor size (P=0.026), lymph node metastasis (P=0.035) and clinical stage (P=0.004). Moreover, Kaplan-Meier curves with the log-rank test showed that higher expression of NEAT1 led to a significantly poorer survival and multivariate Cox proportional hazards analysis revealed that NEAT1 was an independent risk factor of overall survival (OS). We also assessed the function of NEAT1 in vitro by gain-/loss-of-function studies. Results showed that enhanced expression of NEAT1 stimulated the proliferation of ESCC cells, and promoted their ability of forming foci, migration, and invasion. Conversely, knockdown of NEAT1 showed the opposite effect. Overall, our study indicated that the inappropriate activation of NEAT1 predicts poor prognosis and has a crucial regulatory role in in ESCC. Targeting NEAT1 could be a novel therapeutic choice for treating ESCC patients.

Global identification of the genetic networks and cis-regulatory elements of the cold response in zebrafish

The transcriptional programs of ectothermic teleosts are directly influenced by water temperature. However, the cis- and trans-factors governing cold responses are not well characterized. We profiled transcriptional changes in eight zebrafish tissues exposed to mildly and severely cold temperatures using RNA-Seq. A total of 1943 differentially expressed genes (DEGs) were identified, from which 34 clusters representing distinct tissue and temperature response expression patterns were derived using the k-means fuzzy clustering algorithm. The promoter regions of the clustered DEGs that demonstrated strong co-regulation were analysed for enriched cis-regulatory elements with a motif discovery program, DREME. Seventeen motifs, ten known and seven novel, were identified, which covered 23% of the DEGs. Two motifs predicted to be the binding sites for the transcription factors Bcl6 and Jun, respectively, were chosen for experimental verification, and they demonstrated the expected cold-induced and cold-repressed patterns of gene regulation. Protein interaction modeling of the network components followed by experimental validation suggested that Jun physically interacts with Bcl6 and might be a hub factor that orchestrates the cold response in zebrafish. Thus, the methodology used and the regulatory networks uncovered in this study provide a foundation for exploring the mechanisms of cold adaptation in teleosts.

BCL6 is a negative prognostic factor and exhibits pro-oncogenic activity in ovarian cancer

BACKGROUND

Dysregulation of BCL6 plays critical oncogenic roles and facilitates tumorigenesis in various malignancies. However, whether the aberrant expression of BCL6 in ovarian carcinoma is associated with malignancy, metastasis or prognosis remains unknown. Our study aimed to investigate the expression of BCL6 in ovarian carcinoma and its possible correlation with clinicopathological features as well as patient survival to reveal its biological effects in ovarian tumor progression.

METHODS

Immunochemistry analysis was performed in 105 cases of ovarian carcinoma covering the histological types of serous, endometrioid and clear cell. Spearman analysis was used to calculate the correlation between pathological parameters and the expression of BCL6. Kaplan-Meier method and Cox proportional hazards analysis were used to analyze the disease-specific survival (DSS) and disease-free survival (DFS). We also assessed whether overexpression and knockdown of BCL6 influence in vitro cell proliferation, cell cycle progression, as well as tumor cell invasion and migration.

RESULTS

The expression of BCL6 was higher in all three major kinds of ovarian cancer in comparison with paratumorous epithelium. BCL6 expression was tightly correlated with FIGO staging, lymph node metastasis and recurrence. Higher expression of BCL6 led to a significantly poorer DSS and DFS and multivariate analysis revealed that BCL6 was an independent risk factor of DSS and DFS. Enforced overexpression of BCL6 in ovarian tumor cells stimulated proliferation by inducing G1-S transition, and promoted tumor cell invasion and migration. Conversely, RNA interference-mediated silencing BCL6 expression inhibited proliferation by altered cell cycle progression and reduced the ability of the cells to migrate, and invade the extracellular matrix in culture.

CONCLUSIONS

Our study suggests that the inappropriate activation of BCL6 predicts poor prognosis and promotes tumor progression in ovarian carcinoma. Targeting BCL6 could be a novel therapeutic choice for treating ovarian carcinoma patients.

Interleukin-32α downregulates the activity of the B-cell CLL/lymphoma 6 protein by inhibiting protein kinase Cε-dependent SUMO-2 modification

A proinflammatory cytokine IL-32 acts as an intracellular mediator. IL-32α interacts with many intracellular molecules, but there are no reports of interaction with a transcriptional repressor BCL6. In this study, we showed that PMA induces an interaction between IL-32α, PKCε, and BCL6, forming a trimer. To identify the mechanism of the interaction, we treated cells with various inhibitors. In HEK293 and THP-1 cell lines, treatment with a pan-PKC inhibitor, PKCε inhibitor, and PKCδ inhibitor decreased BCL6 and IL-32α protein expression. MAPK inhibitors and classical PKC inhibitor did not decrease PMA-induced BCL6 and IL-32α protein expression. Further, the pan-PKC inhibitor and PKCε inhibitor disrupted PMA-induced interaction between IL-32α and BCL6. These data demonstrate that the intracellular interaction between IL-32α and BCL6 is induced by PMA-activated PKCε. PMA induces post-translational modification of BCL6 by conjugation to SUMO-2, while IL-32α inhibits. PKCε inhibition eliminated PMA-induced SUMOylation of BCL6. Inhibition of BCL6 SUMOylation by IL-32α affected the cellular function and activity of the transcriptional repressor BCL6 in THP-1 cells. Thus, we showed that IL-32α is a negative regulator of the transcriptional repressor BCL6. IL-32α inhibits BCL6 SUMOylation by activating PKCε, resulting in the modulation of BCL6 target genes and cellular functions of BCL6.

Inhibition of ZEB1 by miR-200 characterizes Helicobacter pylori-positive gastric diffuse large B-cell lymphoma with a less aggressive behavior

Primary gastric diffuse large B-cell lymphomas may or may not have a concurrent component of mucosa-associated lymphoid tissue lymphoma. Diffuse large B-cell lymphoma/mucosa-associated lymphoid tissue lymphomas are often associated with Helicobacter pylori (H. pylori) infection, suggesting that the large cells are transformed from mucosa-associated lymphoid tissue lymphomas. In contrast, only limited data are available on the clinical and molecular features of pure gastric diffuse large B-cell lymphomas. In 102 pure gastric diffuse large B-cell lymphomas, we found H. pylori infection in 53% of the cases. H. pylori-positive gastric diffuse large B-cell lymphomas were more likely to present at an earlier stage (73% vs 52% at stage I/II, P=0.03), to achieve complete remission (75% vs 43%, P=0.001), and had a better 5-year disease-free survival rate (73% vs 29%, P<0.001) than H. pylori-negative gastric diffuse large B-cell lymphomas. Through genome-wide expression profiles of both miRNAs and mRNAs in nine H. pylori-positive and nine H. pylori-negative gastric diffuse large B-cell lymphomas, we identified inhibition of ZEB1 (zinc-finger E-box-binding homeobox 1) by miR-200 in H. pylori-positive gastric diffuse large B-cell lymphomas. ZEB1, a transcription factor for marginal zone B cells, can suppress BCL6, the master transcription factor for germinal center B cells. In 30 H. pylori-positive and 30 H. pylori-negative gastric diffuse large B-cell lymphomas, we confirmed that H. pylori-positive gastric diffuse large B-cell lymphomas had higher levels of miR-200 by qRT-PCR, and lower levels of ZEB1 and higher levels of BCL6 using immunohistochemistry. As BCL6 is a known predictor of a better prognosis in gastric diffuse large B-cell lymphomas, our data demonstrate that inhibition of ZEB1 by miR-200, with secondary increase in BCL6, is a molecular event that characterizes H. pylori-positive gastric diffuse large B-cell lymphomas with a less aggressive behavior.

Nuclear magnetic resonance structure of the cytoplasmic tail of heparin binding EGF-like growth factor (proHB-EGF-CT) complexed with the ubiquitin homology domain of Bcl-2-associated athanogene 1 from Mus musculus (mBAG-1-UBH)

The membrane form of heparin binding EGF-like growth factor (proHB-EGF) yields secreted HB-EGF and a membrane-anchored cytoplasmic tail (proHB-EGF-CT), which may be targeted to the nuclear membrane after a shedding stimulus. Bcl-2-associated athanogene 1 (BAG-1) accumulates in the nuclei and inhibits apoptosis in adenoma-derived cell lines. The maintenance of high levels of nuclear BAG-1 enhances cell survival. However, the ubiquitin homology domain of BAG-1 from Mus musculus (mBAG-1-UBH) is proposed to interact with proHB-EGF-CT, and this interaction may enhance the cytoprotection against the apoptosis inducer. The mechanism of the synergistic anti-apoptosis function of proHB-EGF-CT and mBAG-1-UBH is still unknown. We offer a hypothesis that proHB-EGF-CT can maintain high levels of nuclear BAG-1. In this study, we first report the three-dimensional nuclear magnetic resonance structure of proHB-EGF-CT complexed with mBAG-1-UBH. In the structure of the complex, the residues in the C-terminus and one turn between β-strands β1 and β2 of mBAG-1-UBH bind to two terminals of proHB-EGF-CT, which folds into a loop with end-to-end contact. This end-to-end folding of proHB-EGF-CT causes the basic amino acids to colocalize and form a positively charged groove. The dominant forces in the binding interface between proHB-EGF-CT and mBAG-1-UBH are charge-charge interactions. On the basis of our mutagenesis results, the basic amino acid cluster in the N-terminus of proHB-EGF-CT is the crucial binding site for mBAG-1-UBH, whereas another basic amino acid in the C-terminus facilitates this interaction. Interestingly, the mBAG-1-UBH binding region on the proHB-EGF-CT peptide is also involved in the region found to be important for nuclear envelope targeting, supporting the hypothesis that proHB-EGF-CT is most likely able to trigger the nuclear translocation of BAG-1 in keeping its level high.

The zinc finger transcription factor ZXDC activates CCL2 gene expression by opposing BCL6-mediated repression

The zinc finger X-linked duplicated (ZXD) family of transcription factors has been implicated in regulating transcription of major histocompatibility complex class II genes in antigen presenting cells; roles beyond this function are not yet known. The expression of one gene in this family, ZXD family zinc finger C (ZXDC), is enriched in myeloid lineages and therefore we hypothesized that ZXDC may regulate myeloid-specific gene expression. Here we demonstrate that ZXDC regulates genes involved in myeloid cell differentiation and inflammation. Overexpression of the larger isoform of ZXDC, ZXDC1, activates expression of monocyte-specific markers of differentiation and synergizes with phorbol 12-myristate 13-acetate (which causes differentiation) in the human leukemic monoblast cell line U937. To identify additional gene targets of ZXDC1, we performed gene expression profiling which revealed multiple inflammatory gene clusters regulated by ZXDC1. Using a combination of approaches we show that ZXDC1 activates transcription of a gene within one of the regulated clusters, chemokine (C-C motif) ligand 2 (CCL2; monocyte chemoattractant protein 1; MCP1) via a previously defined distal regulatory element. Further, ZXDC1-dependent up-regulation of the gene involves eviction of the transcriptional repressor B-cell CLL/lymphoma 6 (BCL6), a factor known to be important in resolving inflammatory responses, from this region of the promoter. Collectively, our data show that ZXDC1 is a regulator in the process of myeloid function and that ZXDC1 is responsible for Ccl2 gene de-repression by BCL6.

Nuclear translocation of the cytoplasmic domain of HB-EGF induces gastric cancer invasion

Background

Membrane-anchored heparin-binding epidermal growth factor-like growth factor (proHB-EGF) yields soluble HB-EGF, which is an epidermal growth factor receptor (EGFR) ligand, and a carboxy-terminal fragment of HB-EGF (HB-EGF-CTF) after ectodomain shedding. We previously reported that HB-EGF-CTF and unshed proHB-EGF which has the cytoplasmic domain of proHB-EGF (HB-EGF-C), translocate from the plasma membrane to the nucleus and regulate cell cycle after shedding stimuli. However, the significance of nuclear exported HB-EGF-C in human gastric cancer is unclear.

Methods

We investigated the relationship between intracellular localization of HB-EGF-C and clinical outcome in 96 gastric cancer patients treated with gastrectomy. Moreover, we established stable gastric cancer cell lines overexpressing wild-type HB-EGF (wt-HB-EGF) and mutated HB-EGF (HB-EGF-mC), which prevented HB-EGF-C nuclear translocation after shedding. Cell motility between these 2 gastric cancer cell lines was investigated using a transwell invasion assay and a wound healing assay.

Results

Of the 96 gastric cancer cases, HB-EGF-C immunoreactivity was detected in both the nucleus and cytoplasm in 19 cases (19.8 %) and in the cytoplasm only in 25 cases (26.0 %). The nuclear immunoreactivity of HB-EGF-C was significantly increased in stage pT3/4 tumors compared with pT1/2 tumors (T1/2 vs. T3/4: 11.1 % vs. 36.4 %, P < 0.01). The growth of wt-HB-EGF- and HB-EGF-mC-expressing cells significantly increased compared with control cells, but the growth of HB-EGF-mC-expressing cells was significantly decreased compared with wt-HB-EGF-expressing cells. Gastric cancer cell invasion obviously increased in wt-HB-EGF-expressing cells, but invasion in HB-EGF-mC-expressing cells showed a slight increase compared with control cells. Moreover, wt-HB-EGF overexpression increased the effectiveness of wound healing, but had no significant effect in HB-EGF-mC-expressing cells.

Conclusions

Both the function of HB-EGF as an EGFR ligand and a novel signal for HB-EGF-C nuclear translocation induce gastric cancer growth, whereas HB-EGF-C nuclear translocation independently plays a critical role in gastric cancer invasion. The present study demonstrated that HB-EGF-C nuclear translocation might be crucial in gastric cancer invasion. HB-EGF-C nuclear translocation may offer a prognostic marker and a new molecular target for gastric cancer therapy.

Heparin-binding EGF-like growth factor promotes epithelial-mesenchymal transition in human keratinocytes

We have shown that autocrine proliferation of human keratinocytes (KC) is strongly dependent upon amphiregulin (AREG), whereas blockade of heparin-binding EGF-like growth factor (HB-EGF) inhibits KC migration in scratch wound assays. Here we demonstrate that expression of soluble HB-EGF (sHB-EGF) or full-length transmembrane HB-EGF (proHB-EGF), but not proAREG, results in profound increases in KC migration and invasiveness in monolayer culture. Coincident with these changes, HB-EGF significantly decreases mRNA expression of several epithelial markers including keratins 1, 5, 10, and 14, while increasing expression of markers of cellular motility including SNAI1, ZEB1, COX-2 and MMP1. Immunostaining revealed HB-EGF-induced expression of the mesenchymal protein vimentin and decreased expression of E-cadherin as well as nuclear translocation of β-catenin. Suggestive of a trade-off between KC motility and proliferation, overexpression of HB-EGF also reduced KC growth by more than 90%. We also show that HB-EGF is strongly induced in regenerating epidermis after partial thickness wounding of human skin. Taken together, our data suggest that expression of HB-EGF in human KC triggers a migratory and invasive phenotype with many features of epithelial-mesenchymal transition (EMT), which may be beneficial in the context of cutaneous wound healing.

When urothelial differentiation pathways go wrong: implications for bladder cancer development and progression

Differentiation is defined as the ability of a cell to acquire full functional behavior. For instance, the function of bladder urothelium is to act as a barrier to the diffusion of solutes into or out of the urine after excretion by the kidney. The urothelium also serves to protect the detrusor muscle from toxins present in stored urine. A major event in the initiation and progression of bladder cancer is loss of urothelial differentiation. This is important because less differentiated urothelial tumors (higher histologic tumor grade) are typically associated with increased biologic and clinical aggressiveness. The differentiation status of urothelial carcinomas can be assessed by histopathologic examination and is reflected in the assignment of a histologic grade (low-grade or high-grade). Although typically limited to morphologic evaluation in most routine diagnostic practices, tumor grade can also be assessed using biochemical markers. Indeed, current pathological analysis of tumor specimens is increasingly reliant on molecular phenotyping. Thus, high priorities for bladder cancer research include identification of (1) biomarkers that will enable the identification of high grade T1 tumors that pose the most threat and require the most aggressive treatment; (2) biomarkers that predict the likelihood that a low grade, American Joint Committee on Cancer stage pTa bladder tumor will progress into an invasive carcinoma with metastatic potential; (3) biomarkers that indicate which pTa tumors are most likely to recur, thus enabling clinicians to prospectively identify patients who require aggressive treatment; and (4) how these markers might contribute to biological processes that underlie tumor progression and metastasis, potentially through loss of terminal differentiation. This review will discuss the proteins associated with urothelial cell differentiation, with a focus on those implicated in bladder cancer, and other proteins that may be involved in neoplastic progression. It is hoped that ongoing discoveries associated with the study of these differentiation-promoting proteins can be translated into the clinic to positively impact patient care.

Follicular helper CD4 T cells (TFH)

T cell help to B cells is a fundamental aspect of adaptive immunity and the generation of immunological memory. Follicular helper CD4 T (T(FH)) cells are the specialized providers of B cell help. T(FH) cells depend on expression of the master regulator transcription factor Bcl6. Distinguishing features of T(FH) cells are the expression of CXCR5, PD-1, SAP (SH2D1A), IL-21, and ICOS, among other molecules, and the absence of Blimp-1 (prdm1). T(FH) cells are important for the formation of germinal centers. Once germinal centers are formed, T(FH) cells are needed to maintain them and to regulate germinal center B cell differentiation into plasma cells and memory B cells. This review covers T(FH) differentiation, T(FH) functions, and human T(FH) cells, discussing recent progress and areas of uncertainty or disagreement in the literature, and it debates the developmental relationship between T(FH) cells and other CD4 T cell subsets (Th1, Th2, Th17, iTreg).

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.