Stimulation of CD30 in anaplastic large cell lymphoma leads to production of nuclear factor-kappaB p52, which is associated with hyperphosphorylated Bcl-3

Insights on the NF-κB system in polycystic ovary syndrome, attractive therapeutic targets

The nuclear factor κappa B (NF-κB) signaling plays a well-known function in inflammation and regulates a wide variety of biological processes. Low-grade chronic inflammation is gradually considered to be closely related to the pathogenesis of Polycystic ovary syndrome (PCOS). In this review, we provide an overview on the involvement of NF-κB in the progression of PCOS particularly, such as hyperandrogenemia, insulin resistance, cardiovascular diseases, and endometrial dysfunction. From a clinical perspective, progressive recognition of NF-κB pathway provides opportunities for therapeutic interventions aimed at inhibiting pathway-specific mechanisms. With the accumulation of basic experimental and clinical data, NF-κB signaling pathway was recognized as a therapeutic target. Although there have been no specific small molecule NF-κB inhibitors in PCOS, a plethora of natural and synthetic compound have emerged for the pharmacologic intervention of the pathway. The traditional herbs developed for NF-κB pathway have become increasingly popular in recent years. Abundant evidence elucidated that NF-κB inhibitors can significantly improve the symptoms of PCOS. Herein, we summarized evidence relating to how NF-κB pathway is involved in the development and progression of PCOS. Furthermore, we present an in-depth overview of NF-κB inhibitors for therapy interventions of PCOS. Taken together, the NF-κB signaling may be a futuristic treatment strategy for PCOS.

Diverse B-cell tumors associated with t(14;19)(q32;q13)/IGH::BCL3 identified by G-banding and fluorescence in situ hybridization

We characterized 5 B-cell tumors carrying t(14;19)(q32;q13) that creates the IGH::BCL3 fusion gene. The patients' ages ranged between 55 and 88 years. Two patients presented with progression or recurrence of B-cell chronic lymphocytic leukemia (B-CLL)/small lymphocytic lymphoma (SLL), two with diffuse large B-cell lymphoma (DLBCL) of non-germinal center B-like phenotype, and the remaining one with composite angioimmunoblastic T-cell lymphoma and Epstein-Barr virus-positive DLBCL. The presence of t(14;19)(q32;q13) was confirmed by fluorescence in situ hybridization (FISH), showing colocalization of 3' IGH and 3' BCL3 probes on der(14)t(14;19) and 5' BCL3 and 5' IGH probes on der(19)t(14;19). One B-CLL case had t(2;14)(p13;q32)/IGH::BCL11A, and 2 DLBCL cases had t(8;14)(q24;q32) or t(8;11;14)(q24;q11;q32), both of which generated IGH::MYC by FISH, and showed nuclear expression of MYC and BCL3 by immunohistochemistry. The IGH::BCL3 fusion gene was amplified by long-distance polymerase chain reaction in 2 B-CLL/SLL cases and the breakpoints occurred immediately 5' of BCL3 exon 1 and within the switch region associated with IGHA1. The 5 cases shared IGHV preferentially used in B-CLL cells, but the genes were unmutated in 2 B-CLL/SLL cases and significantly mutated in the remaining 3. B-cell tumors with t(14;19)(q32;q13) can be divided into B-CLL/SLL and DLBCL groups, and the anatomy of IGH::BCL3 in the latter may be different from that of the former.

Comparative Transcriptome Analyses of Gayal (Bos frontalis), Yak (Bos grunniens), and Cattle (Bos taurus) Reveal the High-Altitude Adaptation

Gayal and yak are well adapted to their local high-altitude environments, yet the transcriptional regulation difference of the plateau environment among them remains obscure. Herein, cross-tissue and cross-species comparative transcriptome analyses were performed for the six hypoxia-sensitive tissues from gayal, yak, and cattle. Gene expression profiles for all single-copy orthologous genes showed tissue-specific expression patterns. By differential expression analysis, we identified 3,020 and 1,995 differentially expressed genes (DEGs) in at least one tissue of gayal vs. cattle and yak vs. cattle, respectively. Notably, we found that the adaptability of the gayal to the alpine canyon environment is highly similar to the yak living in the Qinghai-Tibet Plateau, such as promoting red blood cell development, angiogenesis, reducing blood coagulation, immune system activation, and energy metabolism shifts from fatty acid β-oxidation to glycolysis. By further analyzing the common and unique DEGs in the six tissues, we also found that numerous expressed regulatory genes related to these functions are unique in the gayal and yak, which may play important roles in adapting to the corresponding high-altitude environment. Combined with WGCNA analysis, we found that UQCRC1 and COX5A are the shared differentially expressed hub genes related to the energy supply of myocardial contraction in the heart-related modules of gayal and yak, and CAPS is a shared differential hub gene among the hub genes of the lung-related module, which is related to pulmonary artery smooth muscle contraction. Additionally, EDN3 is the unique differentially expressed hub gene related to the tracheal epithelium and pulmonary vasoconstriction in the lung of gayal. CHRM2 is a unique differentially expressed hub gene that was identified in the heart of yak, which has an important role in the autonomous regulation of the heart. These results provide a basis for further understanding the complex transcriptome expression pattern and the regulatory mechanism of high-altitude domestication of gayal and yak.

5-HTP decreases goat mammary epithelial cells apoptosis through MAPK/ERK/Bcl-3 pathway

Serotonin (5-HT) is a monoamine and it could regulate cell growth by its receptors working on signaling pathways. 5-HTP is the precursor of 5-HT that help 5-HT synthesis. B cell leukemia/lymphoma 3 (Bcl-3) involved in cell death and proliferation through mitogen activated protein kinase (MAPK) pathway. However, there is little information about the effects of MAPK/Bcl-3 on apoptosis of goat mammary gland epithelial cells (GMECs). The aim of this study is to explore the interaction among 5-HTP, MAPK and Bcl-3 in GMEC apoptosis. In this study, 5-HTP treatment decreased cell apoptosis and promoted phosphorylation of ERK1/2 in GMEC. We also found that the activation and inhibition of ERK1/2 could affect GMEC apoptosis. The Annexin V-FITC/PI staining and western blotting results suggested that 5-HTP decreased GMEC apoptosis through ERK1/2 signaling pathway. And the results of RT-qPCR and western blotting demonstrated that both 5-HTP and ERK1/2 positively regulated Bcl-3 expression. Sum up all the results, we could draw the conclusion that 5-HTP decreased GMEC apoptosis through MAPK/ERK/Bcl-3 pathway.

In vitro studies revealed a downregulation of Wnt/β-catenin cascade by active vitamin D and TX 527 analog in a Kaposi's sarcoma cellular model

The Kaposi's sarcoma-associated herpesvirus G-protein-coupled receptor (vGPCR) is a key molecule in the pathogenesis of Kaposi's sarcoma. We have previously demonstrated that 1α,25(OH)₂D₃ or its less calcemic analog TX 527 exerts antiproliferative effects in endothelial cells stable expressing vGPCR. Since it is well documented that vGPCR activates the canonical Wnt/β-catenin signaling pathway, the aim of this study was to evaluate if Wnt/β-catenin cascade is target of 1α,25(OH)₂D₃ or TX 527 as part of their antineoplastic mechanism. Firstly, Western blot studies showed an increase in β-catenin protein levels in a dose and time dependent manner; and when VDR was knockdown, β-catenin protein levels were significantly decreased. Secondly, β-catenin localization, investigated by immunofluorescence and subcellular fractionation techniques, was found increased in the nucleus and plasma membrane after 1α,25(OH)₂D₃ treatment. VE-cadherin protein levels were also increased in the plasma membrane fraction. Furthermore, β-catenin interaction with VDR was observed by co-immunoprecipitation and mRNA expression of β-catenin target genes was found decreased. Finally, DKK-1, the extracellular inhibitor of Wnt/β-catenin pathway, showed an initial upregulation of mRNA expression. Altogether, the results obtained by different techniques revealed a downregulation of Wnt/β-catenin cascade after 1α,25(OH)₂D₃ or TX 527 treatment, showing the foundation for a potential chemotherapeutic agent.

The proto-oncogene Bcl3 induces immune checkpoint PD-L1 expression, mediating proliferation of ovarian cancer cells

The proto-oncogene Bcl3 induces survival and proliferation in cancer cells; however, its function and regulation in ovarian cancer (OC) remain unknown. Here, we show that Bcl3 expression is increased in human OC tissues. Surprisingly, however, we found that in addition to promoting survival, proliferation, and migration of OC cells, Bcl3 promotes both constitutive and interferon-γ (IFN)-induced expression of the immune checkpoint molecule PD-L1. The Bcl3 expression in OC cells is further increased by IFN, resulting in increased PD-L1 transcription. The mechanism consists of an IFN-induced, Bcl3- and p300-dependent PD-L1 promoter occupancy by Lys-314/315 acetylated p65 NF-κB. Blocking PD-L1 by neutralizing antibody reduces proliferation of OC cells overexpressing Bcl3, suggesting that the pro-proliferative effect of Bcl3 in OC cells is partly mediated by PD-L1. Together, this work identifies PD-L1 as a novel target of Bcl3, and links Bcl3 to IFNγ signaling and PD-L1-mediated immune escape.

Understanding CD30 biology and therapeutic targeting: a historical perspective providing insight into future directions

CD30 is a member of the tumor necrosis factor receptor superfamily. It is characteristically expressed in certain hematopoietic malignancies, including anaplastic large cell lymphoma and Hodgkin lymphoma, among others. The variable expression of CD30 on both normal and malignant lymphoid cells has focused research efforts on understanding the pathogenesis of CD30 upregulation, its contribution to lymphomagenesis through anti-apoptotic mechanisms, and its effect on cell survival. Given the restriction of CD30 to certain tumor types, the logical extension of this has been to attempt to exploit it as a therapeutic target. The efficacy of naked anti-CD30 antibodies in practice was, however, modest. Moreover, combinations with bacterial toxins and radioimmunoconjugates have also had limited success. The development of the antibody-drug compound brentuximab vedotin (BV), however, has rejuvenated interest in CD30 as a tumor target. Phase I and II clinical trials in Hodgkin lymphoma, peripheral T-cell lymphoma, cutaneous T cell lymphoma, and even CD30-expressing B-cell lymphomas, have shown the compound is well tolerated, but more importantly, able to deliver meaningful disease control even in patients with multiply relapsed or refractory disease. FDA approval has been granted for its use in relapsed Hodgkin lymphoma and systemic anaplastic large cell lymphoma. A recent phase III trial of BV in cutaneous T-cell lymphoma has confirmed its superiority to standard of care therapies. In this manuscript, we explore the history of CD30 as a tumor marker and as a therapeutic target, both in the laboratory and in the clinic, with a view to understanding future avenues for further study.

Bcl3 Phosphorylation by Akt, Erk2, and IKK Is Required for Its Transcriptional Activity

Unlike prototypical IκB proteins, which are inhibitors of NF-κB RelA, cRel, and RelB dimers, the atypical IκB protein Bcl3 is primarily a transcriptional coregulator of p52 and p50 homodimers. Bcl3 exists as phospho-protein in many cancer cells. Unphosphorylated Bcl3 acts as a classical IκB-like inhibitor and removes p50 and p52 from bound DNA. Neither the phosphorylation site(s) nor the kinase(s) phosphorylating Bcl3 is known. Here we show that Akt, Erk2, and IKK1/2 phosphorylate Bcl3. Phosphorylation of Ser33 by Akt induces switching of K48 ubiquitination to K63 ubiquitination and thus promotes nuclear localization and stabilization of Bcl3. Phosphorylation by Erk2 and IKK1/2 of Ser114 and Ser446 converts Bcl3 into a transcriptional coregulator by facilitating its recruitment to DNA. Cells expressing the S114A/S446A mutant have cellular proliferation and migration defects. This work links Akt and MAPK pathways to NF-κB through Bcl3 and provides mechanistic insight into how Bcl3 functions as an oncoprotein through collaboration with IKK1/2, Akt, and Erk2.

The non-canonical NF-κB pathway in immunity and inflammation

The nuclear factor-κB (NF-κB) family of transcription factors is activated by canonical and non-canonical signalling pathways, which differ in both signalling components and biological functions. Recent studies have revealed important roles for the non-canonical NF-κB pathway in regulating different aspects of immune functions. Defects in non-canonical NF-κB signalling are associated with severe immune deficiencies, whereas dysregulated activation of this pathway contributes to the pathogenesis of various autoimmune and inflammatory diseases. Here we review the signalling mechanisms and the biological function of the non-canonical NF-κB pathway. We also discuss recent progress in elucidating the molecular mechanisms regulating non-canonical NF-κB pathway activation, which may provide new opportunities for therapeutic strategies.

Stratifying melanoma and breast cancer TCGA datasets on the basis of the CNV of transcription factor binding sites common to proliferation- and apoptosis-effector genes

Transcription factors that activate both proliferation- and apoptosis-effector genes, along with a number of related observations, have led to a proposal for a feed forward mechanism of activating the two gene classes, whereby a certain concentration of a transcription factor activates the proliferation-effector genes and a higher concentration of the transcription factor activates the apoptosis-effector genes. We reasoned that this paradigm of regulation could lead to, in the cancer setting, a selection for relatively reduced copy numbers of apoptosis-effector gene, transcription factor binding sites (TFBS). Thus, the aim of this investigation was to examine the DNA sequencing read depths of TFBS for a set of proliferation- and apoptosis-effector genes, normalized to the read depths found in matching blood samples, as provided by the cancer genome atlas (TCGA); and thereby document copy number differences among these TFBS. We determined that the melanoma and breast cancer, TCGA datasets could be divided into three categories: (i) no detectable copy number variation for the proliferation- and apoptosis-effector, shared TFBS; (ii) a relative increase in the copy number of proliferation-effector gene TFBS, compared with the copy number of the apoptosis-effector gene TFBS; and (iii) a relative decrease in the number of proliferation-effector gene TFBS. Thus, we conclude that changes in the relative copies of the shared TFBS, for proliferation- and apoptosis-effector genes, have the potential of impacting tumor cell proliferative and apoptotic capacities.

Aptamers for CD Antigens: From Cell Profiling to Activity Modulation

Nucleic acid-based aptamers are considered to be a promising alternative to antibodies because of their strong and specific binding to diverse targets, fast and inexpensive chemical synthesis, and easy labeling with a fluorescent dye or therapeutic agent. Cluster of differentiation (CD) proteins are among the most popular antigens for aptamers on the cell surface. These anti-CD aptamers could be used in cell biology and biomedicine, from simple cell phenotyping by flow cytometry or fluorescent microscopy to diagnosis and treatment of HIV/AIDS to cancer and immune therapies. The unique feature of aptamers is that they can act simultaneously as an agonist and antagonist of CD receptors depending on a degree of aptamer oligomerization. Aptamers can also deliver small interfering RNA to silence vital genes in CD-positive cells. In this review, we summarize nucleic acid sequences of anti-CD aptamers and their use, which have been validated in multiple studies.

Aptamers in hematological malignancies and their potential therapeutic implications

Aptamers are short DNA/RNA oligonucleotides selected by the process called Systematic Evolution of Ligands by Exponential Enrichment (SELEX). Due to their functional similarity to monoclonal antibodies with some superior characters, such as high specificity and affinity, flexible modification and stability, and lack of toxicity and immunogenicity, they are promising alternative and complementary targeted therapy for hematologic malignancies. The trends in aptamer technology including production, selection, modifications are briefly discussed in this review. The key aspect is to illustrate aptamers against cancer cells in hematologic malignancies especially those that have entered clinical trials. We also discuss some challenges remain in the application of aptamers.

TCGA: Increased oncoprotein coding region mutations correlate with a greater expression of apoptosis-effector genes and a positive outcome for stomach adenocarcinoma

Oncogene mutations are primarily thought to facilitate uncontrolled cell growth. However, overexpression of oncoproteins likely leads to apoptosis in a feed forward mechanism, whereby a certain level of oncoprotein leads to the activation of pro-proliferation effector genes and higher levels lead to activation of pro-apoptotic effector genes. TCGA STAD barcodes having no oncoprotein coding region mutations represented reduced expression of the apoptosis-effector genes compared with barcodes with multiple oncoprotein coding region mutations. Furthermore, STAD barcodes in a "no-subsequent tumor" group, representing 224 samples, and in a "positive outcome" group, had more oncoprotein coding regions mutated, on average, than barcodes of the new tumor and negative outcome groups, respectively. BRAF, CTNNB1, KRAS and MTOR coding region mutations (as a group) had the strongest association with the no-subsequent tumor group. Tumor suppressor coding region mutations were also correlated with no-subsequent tumor. These results are consistent with an oncoprotein-mediated, feed-forward mechanism of apoptosis in patients. Importantly, the no-subsequent tumor group also had more overall mutations. This result leads to considerations of unhealthy cells or cells with more neo-antigens for immune rejection. However, a probabilistic aspect of mutagenesis is also consistent with more oncoprotein and tumor suppressor protein mutations, in cases of more overall mutations, and thus a higher likelihood of activation of feed forward apoptosis pathways.

The oncogenic transcription factor IRF4 is regulated by a novel CD30/NF-κB positive feedback loop in peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCLs) are generally aggressive non-Hodgkin lymphomas with poor overall survival rates following standard therapy. One-third of PTCLs express interferon regulatory factor-4 (IRF4), a tightly regulated transcription factor involved in lymphocyte growth and differentiation. IRF4 drives tumor growth in several lymphoid malignancies and has been proposed as a candidate therapeutic target. Because direct IRF4 inhibitors are not clinically available, we sought to characterize the mechanism by which IRF4 expression is regulated in PTCLs. We demonstrated that IRF4 is constitutively expressed in PTCL cells and drives Myc expression and proliferation. Using an inhibitor screen, we identified nuclear factor κB (NF-κB) as a candidate regulator of IRF4 expression and cell proliferation. We then demonstrated that the NF-κB subunits p52 and RelB were transcriptional activators of IRF4. Further analysis showed that activation of CD30 promotes p52 and RelB activity and subsequent IRF4 expression. Finally, we showed that IRF4 transcriptionally regulates CD30 expression. Taken together, these data demonstrate a novel positive feedback loop involving CD30, NF-κB, and IRF4; further evidence for this mechanism was demonstrated in human PTCL tissue samples. Accordingly, NF-κB inhibitors may represent a clinical means to disrupt this feedback loop in IRF4-positive PTCLs.

The tumor promoter and NF-κB modulator Bcl-3 regulates splenic B cell development

Bcl-3 is an atypical member of the family of IκB proteins. Unlike the classic members, Bcl-3 functions as a nuclear transcriptional cofactor that may, depending on context, promote or suppress genes via association with p50/NF-κB1 or p52/NF-κB2 homodimers. Bcl-3 is also an oncogene, because it is a partner in recurrent translocations in B cell tumors, resulting in deregulated expression. Bcl-3 functions, however, remain poorly understood. We have investigated the role of Bcl-3 in B cells and discovered a previously unknown involvement in the splenic development of these cells. Loss of Bcl-3 in B cells resulted in significantly more marginal zone (MZ) and fewer follicular (FO) B cells. Conversely, transgenic expression of Bcl-3 in B cells generated fewer MZ and more FO B cells. Both Bcl-3(-/-) FO and MZ B cells were more responsive to LPS stimulation compared with their wild-type counterparts, including increased proliferation. By contrast, Bcl-3(-/-) FO B cells were more prone to apoptosis upon BCR stimulation, also limiting their expansion. The data reveal Bcl-3 as a regulator of B cell fate determination, restricting the MZ path and favoring the FO pathway, at least in part, via increased signal-specific survival of the latter, a finding of relevance to its tumorigenic activity.

RIP1 expression is necessary for CD30-mediated cell death induction in anaplastic large-cell lymphoma cells

CD30, a member of the tumor necrosis factor receptor (TNFR) superfamily, is consistently expressed by tumor cells of anaplastic large-cell lymphoma (ALCL). CD30 stimulation induces massive caspase-dependent cell death of ALCL cells in case of canonical NFκB inhibition or proteasome inhibition. However, CD30, a TNFR lacking a death domain (DD), is unable to recruit a death inducing complex containing TRADD (TNFR1-associated DD-protein) or FADD (FAS-associated DD-domain protein) together with the receptor-interacting protein 1 (RIP1) and caspase-8. Thus, the mechanism explaining CD30-induced cell death of lymphocytes remains obscure. Here, we demonstrate that blockage of RIP1 by siRNA or pharmacological inhibition of RIP1 by Necrostatin-1 almost completely prevented CD30-induced cell death. In addition, we revealed CD30-induced accumulation of RIP1 at the cytoplasma membrane of NFκB-inhibited ALCL cells by confocal laser scanning microscopy. Finally, primary ALCL cases can be subdivided into two groups based on the presence or absence of RIP1 as revealed by immunohistology. Taken together, our study identified RIP1 as a crucial mediator of CD30-induced cell death that bears features of apoptosis as well as necroptosis. RIP1 expression in ALCL tumor cells might eligible for the therapeutic application of CD30 antibodies in combination with NFκB/proteasome inhibitors that should result in CD30-induced cell death.

Distinct motifs in the intracellular domain of human CD30 differentially activate canonical and alternative transcription factor NF-κB signaling

The TNF-receptor superfamily member CD30 is expressed on normal and malignant lymphocytes, including anaplastic large cell lymphoma (ALCL) cells. CD30 transmits multiple effects, including activation of NF-κB signaling, cell proliferation, growth arrest and apoptosis. How CD30 generates these pleiotropic effects is currently unknown. Herein we describe ALCL cells expressing truncated forms of the CD30 intracellular domain that allowed us to identify the key regions responsible for transmitting its biological effects in lymphocytes. The first region (CD30_519–537) activated both the alternative and canonical NF-κB pathways as detected by p100 and IκBα degradation, IKKβ-dependent transcription of both IκBα and the cyclin-dependent kinase inhibitor p21^WAF1/CIP1 and induction of cell cycle arrest. In contrast, the second region of CD30 (CD30_538–595) induced some aspects of canonical NF-κB activation, including transcription of IκBα, but failed to activate the alternative NF-κB pathway or drive p21^WAF1/CIP1-mediated cell-cycle arrest. Direct comparison of canonical NF-κB activation by the two motifs revealed 4-fold greater p65 nuclear translocation following CD30_519–537 engagement. These data reveal that independent regions of the CD30 cytoplasmic tail regulate the magnitude and type of NF-κB activation and additionally identify a short motif necessary for CD30-driven growth arrest signals in ALCL cells.

Green tea catechin extract in intervention of chronic breast cell carcinogenesis induced by environmental carcinogens

Sporadic breast cancers are mainly attributable to long-term exposure to environmental factors, via a multi-year, multi-step, and multi-path process of tumorigenesis involving cumulative genetic and epigenetic alterations in the chronic carcinogenesis of breast cells from a non-cancerous stage to precancerous and cancerous stages. Epidemiologic and experimental studies have suggested that green tea components may be used as preventive agents for breast cancer control. In our research, we have developed a cellular model that mimics breast cell carcinogenesis chronically induced by cumulative exposures to low doses of environmental carcinogens. In this study, we used our chronic carcinogenesis model as a target system to investigate the activity of green tea catechin extract (GTC) at non-cytotoxic levels in intervention of cellular carcinogenesis induced by cumulative exposures to pico-molar 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P). We identified that GTC, at a non-cytotoxic, physiologically achievable concentration of 2.5 µg/mL, was effective in suppressing NNK- and B[a]P-induced cellular carcinogenesis, as measured by reduction of the acquired cancer-associated properties of reduced dependence on growth factors, anchorage-independent growth, increased cell mobility, and acinar-conformational disruption. We also detected that intervention of carcinogen-induced elevation of reactive oxygen species (ROS), increase of cell proliferation, activation of the ERK pathway, DNA damage, and changes in gene expression may account for the mechanisms of GTC's preventive activity. Thus, GTC may be used in dietary and chemoprevention of breast cell carcinogenesis associated with long-term exposure to low doses of environmental carcinogens.

Nimbolide retards tumor cell migration, invasion, and angiogenesis by downregulating MMP-2/9 expression via inhibiting ERK1/2 and reducing DNA-binding activity of NF-κB in colon cancer cells

Nimbolide, a plant-derived limonoid has been shown to exert its antiproliferative effects in various cell lines. We demonstrate that nimbolide effectively inhibited proliferation of WiDr colon cancer cells through inhibition of cyclin A leading to S phase arrest. It also caused activation of caspase-mediated apoptosis through the inhibition of ERK1/2 and activation of p38 and JNK1/2. Further nimbolide effectively retarded tumor cell migration and invasion through inhibition of metalloproteinase-2/9 (MMP-2/9) expression, both at the mRNA and protein level. It was also a strong inhibitor of VEGF expression, promoter activity, and in vitro angiogenesis. Finally, nimbolide suppressed the nuclear translocation of p65/p50 and DNA binding of NF-κB, which is an important transcription factor for controlling MMP-2/9 and VEGF gene expression.

Non-canonical NF-κB signaling pathway

The non-canonical NF-κB pathway is an important arm of NF-κB signaling that predominantly targets activation of the p52/RelB NF-κB complex. This pathway depends on the inducible processing of p100, a molecule functioning as both the precursor of p52 and a RelB-specific inhibitor. A central signaling component of the non-canonical pathway is NF-κB-inducing kinase (NIK), which integrates signals from a subset of TNF receptor family members and activates a downstream kinase, IκB kinase-α (IKKα), for triggering p100 phosphorylation and processing. A unique mechanism of NIK regulation is through its fate control: the basal level of NIK is kept low by a TRAF-cIAP destruction complex and signal-induced non-canonical NF-κB signaling involves NIK stabilization. Tight control of the fate of NIK is important, since deregulated NIK accumulation is associated with lymphoid malignancies.

Using an RNA aptamer probe for flow cytometry detection of CD30-expressing lymphoma cells

Aptamers are small molecular ligands composed of short oligonucleotides that bind targets with high affinity. In contrast to antibodies, as synthetic oligonucleotides, aptamers have lower production costs and elicit no antigenic reactions. Therefore, aptamers are potential agents for disease diagnosis and treatment. In this study, we validate a fluorescently labeled RNA aptamer, which has been reported to bind specifically to mouse CD30 proteins in solution, for human CD30 protein recognition on intact cells. The aptamer probe was tested with cultured anaplastic large cell lymphoma and Hodgkin's lymphoma cells that express high levels of CD30. Flow cytometry and fluorescence microscopy showed specific and sensitive binding of the aptamer probe to CD30-expressing lymphoma cells at low concentrations (0.3 nM). Studies performed on multiple cell lines and nuclear cells from healthy donors confirmed that the CD30 aptamer and anti-CD30 antibody, the standard clinical probe, recognized the same set of cells. The potential application of multicolor flow cytometry analysis using the CD30 aptamer probe and antibodies was also shown. In conclusion, the developed CD30 aptamer probe could act as a replacement and/or a supplement for antibodies in the diagnosis of the CD30-expressing lymphomas.

The biology of Hodgkin's lymphoma

Hodgkin's lymphoma was first described in 1832. The aetiology of this lymphoma, however, remained enigmatic for a long time. Only within the past 10 years has the B-cell nature of the pathognomonic Hodgkin and Reed-Sternberg (HRS) cells been revealed, along with several recurrent genetic lesions. The pathogenetic role for Epstein-Barr virus infection has also been substantiated. HRS cells in classical Hodgkin's lymphoma have several characteristics that are unusual for lymphoid tumour cells, and the Hodgkin's lymphoma microenvironment is dominated by an extensive mixed, potentially inflammatory cellular infiltrate. Understanding the contribution of all of these changes to the pathogenesis of this disease is essential for the development of novel therapies.

A global transcriptional view of apoptosis in human T-cell activation

Background

T-cell activation is an essential step of immune response. The process of proper T-cell activation is strictly monitored and regulated by apoptosis signaling. Yet, regulation of apoptosis, an integral and crucial facet during the process of T-cell activation, is not well understood.

Methods

In this study, a Gene-Ontology driven global gene expression analysis coupled with protein abundance and activity assays identified genes and pathways associated with regulation of apoptosis in primary human CD3+ T cells and separately CD4+ and CD8+ T cells.

Results

We identified significantly regulated apoptotic genes in several protein families, such as BCL2 proteins, CASPASE proteins, and TNF receptors, and detailed their transcriptional kinetics during the T-cell activation process. Transcriptional patterns of a few select genes (BCL2A1, BBC3 and CASP3) were validated at the protein level. Many of these apoptotic genes are involved in NF-κB signaling pathway, including TNFRSF10A, TNFRSF10B, TRAF4, TRAF1, TRAF3, and TRAF6. Upregulation of NF-κB and IκB family genes (REL, RELA, and RELB, NFKBIA, NFKBIE and NFKB1) at 48 to 96 hours, supported by the increase of phosphorylated RELA (p65), suggests that the involvement of the NF-κB complex in the process of T-cell proliferation is not only regulated at the protein level but also at the transcriptional level. Examination of genes involved in MAP kinase signalling pathway, important in apoptosis, suggests an induction of p38 and ERK1 cascades in T-cell proliferation (at 48 to 96 hours), which was explored using phosphorylation assays for p38 (MAPK14) and ERK1 (MAPK3). An immediate and short-lived increase of AP-1 activity measured by DNA-binding activity suggests a rapid and transient activation of p38 and/or JNK cascades upon T-cell activation.

Conclusion

This comparative genome-scale, transcriptional analysis of T-cell activation in the CD4+ and CD8+ subsets and the mixed CD3+ population identified many apoptosis genes not previously identified in the context of T-cell activation. Furthermore, it provided a comprehensive temporal analysis of the transcriptional program of apoptosis associated with T-cell activation.

PD-1-PD-1 ligand interaction contributes to immunosuppressive microenvironment of Hodgkin lymphoma

Programmed death-1 (PD-1)-PD-1 ligand (PD-L) signaling system is involved in the functional impairment of T cells such as in chronic viral infection or tumor immune evasion. We examined PD-L expression in lymphoid cell lines and found that they were up-regulated on Hodgkin lymphoma (HL) and several T-cell lymphomas but not on B-cell lymphomas. PD-L expression was also demonstrated in primary Hodgkin/Reed-Sternberg (H/RS) cells. On the other hand, PD-1 was elevated markedly in tumor-infiltrating T cells of HL, and was high in the peripheral T cells of HL patients as well. Blockade of the PD-1 signaling pathway inhibited SHP-2 phosphorylation and restored the IFN-gamma-producing function of HL-infiltrating T cells. According to these results, deficient cellular immunity observed in HL patients can be explained by "T-cell exhaustion," which is led by the activation of PD-1-PD-L signaling pathway. Our finding provides a potentially effective immunologic strategy for the treatment of HL.

CD30-induced signaling is absent in Hodgkin's cells but present in anaplastic large cell lymphoma cells

High CD30 expression in classical Hodgkin's lymphoma and anaplastic large cell lymphoma (ALCL) suggests an important pathogenic role of this cytokine receptor. To test this hypothesis, we investigated CD30 signaling in Hodgkin's and ALCL cell lines by different approaches: 1) CD30 stimulation, 2) CD30 down-regulation, and 3) a combination of both. The effects were determined at the RNA (microarray and real-time quantitative RT-PCR), protein (electrophoretic mobility shift analysis, immunoblot, and flow cytometry), and cellular/functional (proliferation and apoptosis) levels. We demonstrate that Hodgkin's cells are virtually CD30 unresponsive. Neither CD30 stimulation nor CD30 silencing of Hodgkin's cells had any significant effect. In contrast, CD30 stimulation of ALCL cells activated nuclear transcription factor-kappaB (NF-kappaB), induced major transcriptional changes, and decreased proliferation. These effects could be abrogated by down-regulation of CD30. Stimulation of CD30 in ALCL cells, stably transfected with a dominant-negative NF-kappaB inhibitor, induced pronounced caspase activation and massive apoptosis. Our data indicate that 1) CD30 signaling is not effective in Hodgkin's cell lines but is effective in ALCL cell lines, 2) CD30 is probably not significantly involved in the pathogenesis of classical Hodgkin's lymphoma, and 3) CD30 stimulation triggers two competing effects in ALCL cells, namely activation of caspases and NF-kappaB-mediated survival. These data suggest that CD30-targeted therapy in ALCL should be combined with NF-kappaB inhibitors to induce effective cell killing.

A role for the IkappaB family member Bcl-3 in the control of central immunologic tolerance

Bcl-3 is a member of the family of IkappaB inhibitors. Unlike the classical, cytoplasmic IkappaBs, Bcl-3 does not inhibit RelA- or c-Rel-containing NF-kappaB transcription factor dimers. Instead, Bcl-3 can enter the nucleus and modulate NF-kappaB activity, although the underlying mechanism and physiologic function remain largely unknown. Here we identified Bcl-3 as a regulator of immunologic tolerance to self. In parallel with NF-kappaB2, Bcl-3 functions within stroma to generate medullary thymic epithelial cells, which are essential for negative selection of autoreactive T cells. Loss of both NF-kappaB2 and Bcl-3, but not either one alone, led to a profound breakdown in central tolerance resulting in rapid and fatal multiorgan inflammation. These data reveal extensive utilization of the NF-kappaB system to promote central tolerance in the thymus, in apparent contrast with the well-known roles of NF-kappaB to promote inflammation and autoimmunity in the periphery.

CD30 Activates Both the Canonical and Alternative NF-κB Pathways in Anaplastic Large Cell Lymphoma Cells

CD30 is a member of the tumor necrosis factor receptor superfamily whose expression is up-regulated on anaplastic large cell lymphoma (ALCL) and Hodgkin lymphoma (HL) cells. Many different outcomes of CD30 stimulation have been reported, including cell cycle arrest, apoptosis, and activation of the prosurvival transcription factor, NF-kappaB, although this last activity is much less well defined in ALCL cells. In order to better understand the signaling properties of CD30 in cancer, we established a system for the stimulation of CD30 with its physiological ligand. Using this system, CD30 was stimulated on ALCL and HL cells, and the subsequent CD30 signaling properties were characterized. We show that a fraction of ALCL cells rapidly underwent apoptosis following CD30 stimulation, whereas HL cells were unaffected. The surviving ALCL cells exhibited robust activation of both the canonical and alternative NF-kappaB pathways as measured by nuclear translocation of RelA, p50, RelB, and p52, and this culminated in the transactivation of classical NF-kappaB-responsive genes. With prolonged CD30 stimulation, ALCL cells underwent cell cycle arrest that correlated with expression of the cell cycle inhibitor p21(waf1). Furthermore, p21(waf1) expression and cell cycle arrest were found to depend predominantly on the canonical NF-kappaB pathway, since it was reversed by RNA interference-mediated suppression of RelA. In contrast, suppression of the p100/p52 NF-kappaB subunit had little effect on p21(waf1). These data reveal that in ALCL cells, in contrast to other cell types, CD30 stimulation elicits p21(waf1)-mediated arrest through the canonical but not the alternative NF-kappaB pathway.

The alternative NF-kappaB pathway from biochemistry to biology: pitfalls and promises for future drug development

The past two decades have led to a tremendous work on the transcription factor NF-kappaB and its molecular mechanisms of activation. The nuclear translocation of NF-kappaB is controlled by two main pathways: the classical and the alternative NF-kappaB pathways. The classical NF-kappaB pathway activates the IKK complex that controls the inducible degradation of most IkappaB family members that are IkappaBalpha, IkappaBbeta, IkappaBvarepsilon and p105. The alternative NF-kappaB pathway induces p100 processing and p52 generation through the activation of at least two kinases, which are NIK and IKKalpha. Genetic studies have shown that IKKgamma is dispensable for the alternative pathway, which suggests the existence of an alternative IKKalpha-containing complex. It is noteworthy that activation of particular p52 heterodimers like p52/RelB requires solely the alternative pathway while activation of p52/p65 or p52/c-Rel involves a "hybrid pathway". Among others, LTbetaR, BAFF-R, CD40 and RANK have the ability to induce the alternative pathway. The latter plays some roles in biological functions controlled by these receptors, which are the development of secondary lymphoid organs, the proliferation, survival and maturation of B cell, and the osteoclastogenesis. Exacerbated activation of the alternative pathway is potentially associated to a wide range of disorders like rheumatoid arthritis, ulcerative colitis or B cell lymphomas. Therefore, inhibitors of the alternative pathway could be valuable tools for the treatment of inflammatory disorders and cancers.

Fusion tyrosine kinase mediated signalling pathways in the transformation of haematopoietic cells

The fusion tyrosine kinases (FTKs) are generated by chromosomal translocations creating bipartite proteins in which the kinase is hyperactivated by an adjoining oligomerization domain. Autophosphorylation of the FTK generates a 'signalosome', an ensemble of signalling proteins that transduce signals to downstream pathways. At the earliest stages of oncogenesis, FTKs can mimic mitogenic cytokine signalling pathways involving the GAB-2 adaptor protein and signal transducers and activators of transcription (STAT) factors, generating replicative stress and thereby promoting a mutator phenotype. In parallel, FTKs couple to survival pathways that upregulate prosurvival proteins such as Bcl-xL, so preventing DNA-damage-induced apoptosis. Following transformation, FTKs induce resistance to genotoxic attack by upregulating DNA repair mechanisms such as STAT5-dependent RAD51 transcription. The phenomenon of 'oncogene addiction' reflects the continued requirement of an active FTK 'signalosome' to mediate survival and mitogenic signals involving the PI 3-kinase and mitogen-activated protein stress-activated protein kinase pathways, and the nuclear factor-kappa B, activator protein 1 and STAT transcription factors. The available data so far suggest that FTKs, with some possible exceptions, induce and maintain the transformed state using similar panoplies of signals, a finding with important therapeutic implications. The FTK signalling field has matured to an exciting phase in which rapid advances are facilitating rational drug design.

Reappraisal of BCL3 as a Molecular Marker of Anaplastic Large Cell Lymphoma

The BCL3 gene was initially discovered through its involvement in a recurring translocation, t(14;19)(q32;q13), which is found in some patients with B-cell chronic lymphocytic leukemia (B-CLL). The translocation leads to the juxtaposition of BCL3 to the immunoglobulin heavy chain gene locus, resulting in high-level expression of the BCL3 transcript. The Bcl-3 protein includes 7 tandem copies of the ankyrin repeat element in the central domain, a structure that is characteristic of the IkappaB family of inhibitors of the nuclear factor kappaB transcription factors. Anaplastic large cell lymphoma (ALCL) is a subtype of aggressive non-Hodgkin's lymphoma that is characterized by expression of CD30 and the NPM/ALK chimeric protein, which is generated by t(2;5)(p23;q35). We compared the gene expression profiles of ALCL with those of another CD30+ neoplasm, Hodgkin's disease (HD), and found that BCL3 is expressed at higher levels in ALCL than in HD. A comparison by real-time polymerase chain reaction assay revealed that t(2;5)+ ALCL expresses a high level of BCL3 messenger RNA relative to the levels expressed in other hematologic tumors, and the level in ALCL is comparable to or even higher than that in t(14;19)+ B-CLL. An immunohistochemical analysis of ALCL tumor tissues showed that the lymphoma cells exhibited strong nuclear staining by a monoclonal antibody against Bcl-3. We suggest that Bcl-3 sequestrates the (p50)2 homodimer to the nucleus and that the kappaB sites are occupied by the (p50)2/Bcl-3 ternary complex. Future studies should identify the relationships among the 3 independent molecules (ie, NPM/ALK, CD30, and Bcl-3) that are activated in t(2;5)+ ALCL.