APRIL, a new member of the tumor necrosis factor family, modulates death ligand-induced apoptosis

The BAFF-APRIL System in Cancer

B cell-activating factor (BAFF; also known as CD257, TNFSF13B, BLyS) and a proliferation-inducing ligand (APRIL; also known as CD256, TNFSF13) belong to the tumor necrosis factor (TNF) family. BAFF was initially discovered as a B-cell survival factor, whereas APRIL was first identified as a protein highly expressed in various cancers. These discoveries were followed by over two decades of extensive research effort, which identified overlapping signaling cascades between BAFF and APRIL, controlling immune homeostasis in health and driving pathogenesis in autoimmunity and cancer, the latter being the focus of this review. High levels of BAFF, APRIL, and their receptors have been detected in different cancers and found to be associated with disease severity and treatment response. Here, we have summarized the role of the BAFF-APRIL system in immune cell differentiation and immune tolerance and detailed its pathogenic functions in hematological and solid cancers. We also highlight the emerging therapeutics targeting the BAFF-APRIL system in different cancer types.

Regulatory T-Cell Response to Low-Dose Interleukin-2 in Ischemic Heart Disease

BACKGROUND: Atherosclerosis is a chronic inflammatory disease of the artery wall. Regulatory T cells (Tregs) limit inflammation and promote tissue healing. Low doses of interleukin (IL)-2 have the potential to increase Tregs, but its use is contraindicated for patients with ischemic heart disease. METHODS: In this randomized, double-blind, placebo-controlled, dose-escalation trial, we tested low-dose subcutaneous aldesleukin (recombinant IL-2), given once daily for 5 consecutive days. In study part A, the primary end point was safety, and patients with stable ischemic heart disease were randomly assigned to receive placebo or to one of five dose groups (range, 0.3 to 3.0 × 106 IU daily). In study part B, patients with acute non-ST elevation myocardial infarction or unstable angina were randomly assigned to receive placebo or to one of two dose groups (1.5 and 2.5 × 106 IU daily). The coprimary end points were safety and the dose required to increase circulating Tregs by 75%. Single-cell RNA-sequencing of circulating immune cells was used to provide a mechanistic assessment of the effects of aldesleukin. RESULTS: Forty-four patients were randomly assigned to either study part A (n=26) or part B (n=18). In total, 3 patients withdrew before dosing, 27 received active treatment, and 14 received placebo. The majority of adverse events were mild. Two serious adverse events occurred, with one occurring after drug administration. In parts A and B, there was a dose-dependent increase in Tregs. In part B, the estimated dose to achieve a 75% increase in Tregs was 1.46 × 106 IU (95% confidence interval, 1.06 to 1.87). Single-cell RNA-sequencing demonstrated the engagement of distinct pathways and cell–cell interactions. CONCLUSIONS: In this phase 1b/2a study, low-dose IL-2 expanded Tregs without adverse events of major concern. Larger trials are needed to confirm the safety and to further evaluate the efficacy of low-dose IL-2 as an anti-inflammatory therapy for patients with ischemic heart disease. (Funded by the Medical Research Council, the British Heart Foundation, and others; ClinicalTrials.gov number, NCT03113773)

Review article: targeting the B cell activation system in autoimmune hepatitis

BACKGROUND

The B cell activation system, consisting of B cell activating factor and a proliferation-inducing ligand, may have pathogenic effects in autoimmune hepatitis.

AIMS

To describe the biological actions of the B cell activation system, indicate its possible role in autoimmune diseases, and evaluate its prospects as a therapeutic target in autoimmune hepatitis METHODS: English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed.

RESULTS

The B cell activating factor is crucial for the maturation and survival of B cells, and it can co-stimulate T cell activation, proliferation, and survival. It can also modulate the immune response by inducing interleukin 10 production by regulatory B cells. A proliferation-inducing ligand modulates and diversifies the antibody response by inducing class-switch recombination in B cells. It can also increase the proliferation, survival, and antigen activation of T cells. These immune stimulatory actions can be modulated by inducing proliferation of regulatory T cells. The B cell activation system has been implicated in diverse autoimmune diseases, and therapeutic blockade is a management strategy now being evaluated in autoimmune hepatitis.

CONCLUSIONS

The B cell activation system has profound effects on B and T cell function in autoimmune diseases. Blockade therapy is being actively evaluated in autoimmune hepatitis. Clarification of the critical pathogenic components of the B cell activation system will improve the targeting, efficacy, and safety of blockade therapy in this disease.

Phytochemical composition and health properties of Sembung plant (Blumea balsamifera): A review

Indonesia's mindset has been focusing on the use of natural medicines, food, and healing practices widely recognized by the nation's culture. Traditional medicines and herbs used in traditional medicine can often lead to the discovery of drugs against certain diseases. The aim of this review was to study evidence-based data on the importance of Sembung plant, Blumea balsamifera, as a potential traditional medicine. The distribution, ethnopharmacology, secondary metabolites, and bioactivity against several diseases are focused in this review. Information and research related to Sembung plant were searched using the terms "B. balsamifera," "phytochemicals," and "pharmacological activity" on ResearchGate, Google Scholar, Science Direct, PubMed, and scientific information-based databases up to 2020. Several ethnomedical articles recommend B. balsamifera for the treatment of sinusitis, colic pain, cough, kidney stones, flu, or as a diuretic. This knowledge has already been applied in several countries in Southeast Asia. B. balsamifera has been reported to contain several phytochemicals both volatile (terpenoids, fatty acids, phenols, alcohol, aldehydes, ethers, ketones, pyridines, furans, and alkanes) and non-volatile (flavonoids, flavanones, and chalcones). Extracts and phytochemicals of B. balsamifera contain several biological capacities such as antioxidant, antimicrobial, antifungal, anti-inflammatory, hypolipidemic, anti-infertility, hepatoprotective activity, antidiabetic, gastroprotective, antitumor, anticancer, and immunomodulatory agent against Coronavirus disease-19 infection. This review provides essential data for the potential application of B. balsamifera as a nutraceutical or in future medicinal preparations.

Differential Immune Transcriptome and Modulated Signalling Pathways in Rainbow Trout Infected with Viral Haemorrhagic Septicaemia Virus (VHSV) and Its Derivative Non-Virion (NV) Gene Deleted

Viral haemorrhagic septicaemia virus (VHSV) is one of the worst viral threats to fish farming. Non-virion (NV) gene-deleted VHSV (dNV-VHSV) has been postulated as an attenuated virus, because the absence of the NV gene leads to lower induced pathogenicity. However, little is known about the immune responses driven by dNV-VHSV and the wild-type (wt)-VHSV in the context of infection. Here, we obtained the immune transcriptome profiling in trout infected with dNV-VHSV and wt-VHSV and the pathways involved in immune responses. As general results, dNV-VHSV upregulated more trout immune genes than wt-VHSV (65.6% vs 45.7%, respectively), whereas wt-VHSV maintained more non-regulated genes than dNV-VHSV (45.7% vs 14.6%, respectively). The modulated pathways analysis (Gene-Set Enrichment Analysis, GSEA) showed that, when compared to wt-VHSV infected trout, the dNV-VHSV infected trout upregulated signalling pathways (n = 19) such as RIG-I (retinoic acid-inducible gene-I) like receptor signalling, Toll-like receptor signalling, type II interferon signalling, and nuclear factor kappa B (NF-kappa B) signalling, among others. The results from individual genes and GSEA demonstrated that wt-VHSV impaired the activation at short stages of infection of pro-inflammatory, antiviral, proliferation, and apoptosis pathways, delaying innate humoral response and cellular crosstalk, whereas dNV-VHSV promoted the opposite effects. Therefore, these results might support future studies on using dNV-VHSV as a potential live vaccine.

A significant decrease of BAFF, APRIL, and BAFF receptors following mesenchymal stem cell transplantation in patients with refractory rheumatoid arthritis

In the present study, we aimed to evaluate effects of autologous mesenchymal stem cells (MSCs) intravenous administration on the response of B cells, BAFF, APRIL, and their receptors on the surface of B cells at 1, 6, and 12 month follow-up periods in refractory rheumatoid arthritis (RA) patients. Thirteen patients with refractory RA received autologous MSCs. Plasma levels of BAFF and APRIL were measured employing ELISA method, followed by estimating B cell population and BAFFRs evaluation by flow cytometry technique. Gene expression of BAFF, APRIL, and their receptors on B cell surface in PBMCs was evaluated by SYBR Green real-time PCR technique. Plasma concentration of BAFF significantly decreased 1 and 6 months after the MSCT (MSCs Transplantation). Plasma concentration of APRIL significantly decreased 1 month after the MSCT. Percentages of CD19 + B cells in the PBMC population significantly decreased 12 months after the MSCT. Percentages of BR3 + CD19 + B cells and BCMA + CD19 + B cells significantly decreased at the 12th month after the MSCT. The gene expression of BAFF in the PBMC population significantly decreased during 6, and 12 months after the MSCT. The gene expression of APRIL significantly decreased on month 6 after the MSCT. The gene expression of BR3 significantly decreased during 1, 6, and 12 months after the MSCT. The MSCT seems to decrease B cells response because of the reduced production of BAFF and APRIL cytokines and decrease the expression of their receptors on the surface of B cells.

The role of BAFF and APRIL in rheumatoid arthritis

Development and activation of B cells quickly became clear after identifying new ligands and receptors in the tumor necrosis factor superfamily. B cell-activating factor (BAFF) and a proliferation-inducing ligand (APRIL) are the members of membrane proteins Type 2 family released by proteolytic cleavage of furin to form active, soluble homotrimers. Except for B cells, ligands are expressed by all such immune cells like T cells, dendritic cells, monocytes, and macrophages. BAFF and APRIL have two common receptors, namely TNFR homolog transmembrane activator and Ca2+ modulator and CAML interactor (TACI) and B cell-maturation antigen. BAFF alone can also be coupled with a third receptor called BAFFR (also called BR3 or BLyS Receptor). These receptors are often expressed by immune cells in the B-cell lineage. The binding of BAFF or APRIL to their receptors supports B cells differentiation and proliferation, immunoglobulin production and the upregulation of B cell-effector molecules expression. It is possible that the overexpression of BAFF and APRIL contributes to the pathogenesis of autoimmune diseases. In BAFF transgenic mice, there is a pseudo-autoimmune manifestation, which is associated with an increase in B-lymphocytes, hyperglobulinemia, anti-single stranded DNA, and anti-double-stranded DNA antibodies, and immune complexes in their peripheral blood. Furthermore, overexpressing BAFF augments the number of peripheral B220+ B cells with a normal proliferation rate, high levels of Bcl2, and prolonged survival and hyperactivity. Therefore, in this review article, we studied BAFF and APRIL as important mediators in B-cell and discussed their role in rheumatoid arthritis.

Arrayed molecular barcoding identifies TNFSF13 as a positive regulator of acute myeloid leukemia-initiating cells

Dysregulation of cytokines in the bone marrow (BM) microenvironment promotes acute myeloid leukemia (AML) cell growth. Due to the complexity and low throughput of in vivo stem-cell based assays, studying the role of cytokines in the BM niche in a screening setting is challenging. Here, we developed an ex vivo cytokine screen using 11 arrayed molecular barcodes, allowing for a competitive in vivo readout of leukemia-initiating capacity. With this approach, we assessed the effect of 114 murine cytokines on MLL-AF9 AML mouse cells and identified the tumor necrosis factor ligand superfamily member 13 (TNFSF13) as a positive regulator of leukemia-initiating cells. By using Tnfsf13^−/− recipient mice, we confirmed that TNFSF13 supports leukemia initiation also under physiological conditions. TNFSF13 was secreted by normal myeloid cells but not by leukemia mouse cells, suggesting that mature myeloid BM cells support leukemia cells by secreting TNFSF13. TNFSF13 supported leukemia cell proliferation in an NF-κB-dependent manner by binding TNFRSF17 and suppressed apoptosis. Moreover, TNFSF13 supported the growth and survival of several human myeloid leukemia cell lines, demonstrating that our findings translate to human disease. Taken together, using arrayed molecular barcoding, we identified a previously unrecognized role of TNFSF13 as a positive regulator of AML-initiating cells. The arrayed barcoded screening methodology is not limited to cytokines and leukemia, but can be extended to other types of ex vivo screens, where a multiplexed in vivo read-out of stem cell functionality is needed.

Global, Survival, and Apoptotic Transcriptome during Mouse and Human Early Embryonic Development

Survival and cell death signals are crucial for mammalian embryo preimplantation development. However, the knowledge on the molecular mechanisms underlying their regulation is still limited. Mouse studies are widely used to understand preimplantation embryo development, but extrapolation of these results to humans is questionable. Therefore, we wanted to analyse the global expression profiles during early mouse and human development with a special focus on genes involved in the regulation of the apoptotic and survival pathways. We used DNA microarray technology to analyse the global gene expression profiles of preimplantation human and mouse embryos (metaphase II oocytes, embryos at the embryonic genome activation stage, and blastocysts). Components of the major apoptotic and survival signalling pathways were expressed during early human and mouse embryonic development; however, most expression profiles were species-specific. Particularly, the expression of genes encoding components and regulators of the apoptotic machinery were extremely stable in mouse embryos at all analysed stages, while it was more stage-specific in human embryos. CASP3, CASP9, and AIF were the only apoptosis-related genes expressed in both species and at all studied stages. Moreover, numerous transcripts related to the apoptotic and survival pathway were reported for the first time such as CASP6 and IL1RAPL1 that were specific to MII oocytes; CASP2, ENDOG, and GFER to blastocysts in human. These findings open new perspectives for the characterization and understanding of the survival and apoptotic signalling pathways that control early human and mouse embryonic development.

Neutrophil TLR4 and PKR are targets of breast cancer cell glycosaminoglycans and effectors of glycosaminoglycan-induced APRIL secretion

A proliferation-inducing ligand (APRIL), which induces survival and migration signals and tumor growth, is commonly observed in breast cancer tissues but is not often expressed in breast cancer cells themselves. Here, we examined whether breast cancer cells induce APRIL secretion from neutrophils, which are frequently recruited into the breast tumor microenvironment. We found that breast cancer cells do stimulate neutrophils to secrete APRIL through their glycosaminoglycans. Breast cancer cells depleted of heparan sulfate or chondroitin sulfate glycosaminoglycans lose their ability to induce APRIL secretion from neutrophils, and heparan sulfate and chondroitin sulfate can induce secretion that is comparable to that of breast cancer cell-induced secretion. While stimulation of the RNA-activated protein kinase (PKR) is sufficient to induce neutrophil APRIL secretion, both PKR and the toll-like receptor 4 (TLR4) are required for breast cancer cell glycosaminoglycan-induced secretion as separate and specific inhibition of TLR4 or PKR completely prevents the process, suggesting that breast cancer cell glycosaminoglycans target neutrophil TLR4 and PKR to trigger APRIL secretion. Thus, apart from the putative role of cell surface heparan sulfate in binding APRIL that leads to cell growth, we demonstrate that heparan sulfate, as well as chondroitin sulfate plays a novel role in promoting neutrophil secretion of APRIL that could lead to further cell growth. We propose that breast cancer cells take advantage of the neutrophil recruitment to the tumor microenvironment through the dual role of heparan sulfate as cell surface receptor or docking molecule for APRIL and as a ligand that induces neutrophil APRIL secretion to promote their own growth.

The trophic effect of nerve growth factor in primary cultures of rat hippocampal neurons is associated to an anti-inflammatory and immunosuppressive transcriptional program

Nerve growth factor, the prototype of a family of neurotrophins, elicits differentiation and survival of peripheral and central neuronal cells. Although its neural mechanisms have been studied extensively, relatively little is known about the transcriptional regulation governing its effects. We have previously observed that in primary cultures of rat hippocampal neurons treatment with nerve growth factor for 72 hr increases neurite outgrowth and cell survival. To obtain a comprehensive view of the underlying transcriptional program, we performed whole-genome expression analysis by microarray technology. We identified 541 differentially expressed genes and characterized dysregulated pathways related to innate immunity: the complement system and neuro-inflammatory signaling. The exploitation of such genes and pathways may help interfering with the intracellular mechanisms involved in neuronal survival and guide novel therapeutic strategies for neurodegenerative diseases.

Increased expression of A Proliferation-inducing Ligand (APRIL) in lung leukocytes and alveolar epithelial cells in COPD patients with non small cell lung cancer: a possible link between COPD and lung cancer?

Background

Chronic Obstructive Pulmonary Disease (COPD) is characterized by an excessive activation of the adaptive immune system and, in particular, uncontrolled expansion of the B-cell pool. One of the key promoters of B cell expansion is A PRoliferation-Inducing Ligand (APRIL). APRIL has been strongly linked to non small cell lung cancer (NSCLC) onset and progression previously. However, little is known about the expression of APRIL in the lungs of COPD patients.

Methods

Using immuno-fluorescence staining, the expression of APRIL was assessed in sections of lungs from 4 subjects with primary diagnosis of COPD (FEV₁ 33 ± 20 % predicted), 4 subjects with primary diagnosis of NSCLC, 4 subjects diagnosed with both COPD and NSCLC, smokers without COPD or NSCLC and 3 healthy never-smokers. The percentage of B cells, alveolar macrophages (AMs) and polymorphonuclear neutrophils (PMNs) in the lung and alveolar epithelial cells (AECs) that stained positively for APRIL was quantified using epi-fluorescence microscopy and image analysis software.

Results

The percentage of APRIL-expressing B cells, AMs, PMNs and alveolar epithelial cells (AECs) was higher in patients having both COPD and NSCLC than in patients with either COPD or NSCLC alone, SC or NSC (p < 0.03 for all comparisons). The percentage of APRIL-expressing AMs and AECs (but not in B cells) was higher in patients with NSCLC alone than in patients with COPD alone. The percentage of APRIL-expressing AECs (but not B cells or AMs) was higher in COPD patients than in SC and NSC (p < 0.05 for all comparisons). The percentage of APRIL-expressing B cells, AMs and AECs cells was similar in NSC and SC.

Conclusion

The percentage of APRIL-expressing B cells, AMs and AECs is higher in the lungs of patients with both COPD and NSCLC than in patients with COPD or NSCLC alone or control subjects. These findings suggest that APRIL may contribute to the pathogenesis of both COPD and NSCLC, and possibly to the development of NSCLC in patients with established COPD.

High APRIL expression correlates with unfavourable survival of gastrointestinal stromal tumour

A proliferation inducing ligand (APRIL) is a member of the tumour necrosis factor superfamily. High APRIL expression has been found to correlate with tumour development, suggesting that APRIL participates in oncogenesis. However, little is known about APRIL expression in gastrointestinal stromal tumours (GISTs) or the relationship between APRIL expression and the clinical characteristics of GIST. Therefore, we assessed the expression of APRIL immunohistochemically using a tissue microarray from 178 patients with GIST and evaluated the relationship between APRIL expression and patient prognosis. Strong APRIL expression was observed in 42.7% of GISTs, with APRIL expression significantly associated with tumour diameter, gross classification and tumour grade (p < 0.05 each). Kaplan-Meier analysis suggested that low APRIL expression and tumour size <5 cm were associated with longer overall survival. These findings indicate that APRIL expression is correlated with malignant GIST phenotypes and it may serve as an unfavourable prognostic marker in patients with GIST.

Identification of the sAPRIL binding peptide and its growth inhibition effects in the colorectal cancer cells

BACKGROUND

A proliferation-inducing ligand (APRIL) is a member of the tumor necrosis factor (TNF) super family. It binds to its specific receptors and is involved in multiple processes during tumorigenesis and tumor cells proliferation. High levels of APRIL expression are closely correlated to the growth, metastasis, and 5-FU drug resistance of colorectal cancer. The aim of this study was to identify a specific APRIL binding peptide (BP) able to block APRIL activity that could be used as a potential treatment for colorectal cancer.

METHODS

A phage display library was used to identify peptides that bound selectively to soluble recombinant human APRIL (sAPRIL). The peptides with the highest binding affinity for sAPRIL were identified using ELISA. The effects of sAPRIL-BP on cell proliferation and cell cycle/apoptosis in vitro were evaluated using the CCK-8 assay and flow cytometry, respectively. An in vivo mouse model of colorectal cancer was used to determine the anti-tumor efficacy of the sAPRIL-BP.

RESULTS

Three candidate peptides were characterized from eight phage clones with high binding affinity for sAPRIL. The peptide with the highest affinity was selected for further characterization. The identified sAPRIL-BP suppressed tumor cell proliferation and cell cycle progression in LOVO cells in a dose-dependent manner. In vivo in a mouse colorectal challenge model, the sAPRIL-BP reduced the growth of tumor xenografts in nude mice by inhibiting proliferation and inducing apoptosis intratumorally. Moreover, in an in vivo metastasis model, sAPRIL-BP reduced liver metastasis of colorectal cancer cells.

CONCLUSIONS

sAPRIL-BP significantly suppressed tumor growth in vitro and in vivo and might be a candidate for treating colorectal cancers that express high levels of APRIL.

Genomic profiling reveals distinctive molecular relapse patterns in IDH1/2 wild-type glioblastoma

Molecular changes associated with the progression of glioblastoma after standard radiochemotherapy remain poorly understood. We compared genomic profiles of 27 paired primary and recurrent IDH1/2 wild-type glioblastomas by genome-wide array-based comparative genomic hybridization. By bioinformatic analysis, primary and recurrent tumor profiles were normalized and segmented, chromosomal gains and losses identified taking the tumor cell content into account, and difference profiles deduced. Seven of 27 (26%) pairs lacked DNA copy number differences between primary and recurrent tumors (equal pairs). The recurrent tumors in 9/27 (33%) pairs contained all chromosomal imbalances of the primary tumors plus additional ones, suggesting a sequential acquisition of and/or selection for aberrations during progression (sequential pairs). In 11/27 (41%) pairs, the profiles of primary and recurrent tumors were divergent, i.e., the recurrent tumors contained additional aberrations but had lost others, suggesting a polyclonal composition of the primary tumors and considerable clonal evolution (discrepant pairs). Losses on 9p21.3 harboring the CDKN2A/B locus were significantly more common in primary tumors from sequential and discrepant (nonequal) pairs. Nonequal pairs showed ten regions of recurrent genomic differences between primary and recurrent tumors harboring 46 candidate genes associated with tumor recurrence. In particular, copy numbers of genes encoding apoptosis regulators were frequently changed at progression. In summary, approximately 25% of IDH1/2 wild-type glioblastoma pairs have stable genomic imbalances. In contrast, approximately 75% of IDH1/2 wild-type glioblastomas undergo further genomic aberrations and alter their clonal composition upon recurrence impacting their genomic profile, a process possibly facilitated by 9p21.3 loss in the primary tumor. © 2014 Wiley Periodicals, Inc.

Molecular cloning, expression, bioinformatics analysis, and bioactivity of TNFSF13 (APRIL) in the South African clawed frog (Xenopus laevi): a new model to study immunological diseases

TNFSF13 is one of the tumor necrosis factor (TNF) superfamily members that plays important roles in immune homeostasis and proliferation or apoptosis of certain tumor cell lines. This report describes the development of Xenopus laevis TNFSF13 as a model to study its important role in relation to immunological diseases. In brief, TNFSF13 from Xenopus laevis (designated XlTNFSF13) was first amplified by RT-PCR and rapid amplification of cDNA end (RACE) techniques. Bioinformatics analyses revealed the gene structure, three-dimensional structure, and evolutionary relationships. Real-time quantitative PCR (QPCR) analysis identified the tissue distribution of XlTNFSF13 in the major visceral organs. The recombinant plasmid SUMO-XsTNFSF13 was expressed in E. coli Rosseta (DE3). Subsequently, the recombinant protein purified through Ni-NTA affinity chromatography was analyzed by SDS-PAGE and confirmed by Western blot analysis. Laser scanning confocal microscopy analysis revealed the binding activity of pSUMO-XsTNFSF13 to the surface of B cells. WST-8 assays further indicated that purified XsTNFSF13 could cause the survival/proliferation of B cells. In conclusion, we underscore that as a model organism for human disease, Xenopus laevis has been widely used in molecular biology research. Yet while TNFSF13 research in mammalian, fish (e.g., zebrafish), mouse, and human is widely available, studies in the amphibian species are limited. The latter area of OMICS and integrative biology scholarship is directly informed with the present study, with a view to implications for the future study of human immunological diseases.

BAFF, APRIL, TWEAK, BCMA, TACI and Fn14 proteins are related to human glioma tumor grade: immunohistochemistry and public microarray data meta-analysis

Gliomas are common and lethal tumors of the central nervous system (CNS). Genetic alterations, inflammatory and angiogenic processes have been identified throughout tumor progression; however, treatment still remains palliative for most cases. Biological research on parameters influencing cell survival, invasion and tumor heterogeneity identified several cytokines interfering in CNS inflammation, oxidative stress and malignant transformation, including TNF-superfamily (TNFSF) members. In this report we performed a meta-analysis of public gene-array data on the expression of a group of TNFSF ligands (BAFF, APRIL, TWEAK) and their receptors (BAFF-R, TACI, BCMA, Fn14) in gliomas. In addition, we investigated by immunohistochemistry (IHC) the tumor cells' expression of these ligands and receptors in a series of 56 gliomas of different grade. We show that in IHC, BAFF and APRIL as well as their cognate receptors (BCMA, TACI) and Fn14 expression correlate with tumor grade. This result was not evidenced in micro-arrays meta-analysis. Finally, we detected for the first time Fn14, BAFF, BCMA and TACI in glioma-related vascular endothelium. Our data, combined with our previous report in glioma cell lines, suggest a role for these receptors and ligands in glioma biology and advance these molecules as potential markers for the classification of these tumors to the proliferative, angiogenic or stem-like molecular subtype.

Implications of Dll4-Notch signaling activation in primary glioblastoma multiforme

BACKGROUND

Glioblastoma multiforme (GBM) is a highly aggressive brain tumor characterized by massive neovascularization, necrosis, and intense resistance to therapy. Deregulated Notch signaling has been implicated in the formation and progression of different malignancies. The present study attempted to investigate the activation status of Dll4-Notch signaling in primary human GBM and its association with vascular and clinical parameters in patients.

METHODS

Major components of Dll4-Notch signaling were examined by real-time reverse-transcription polymerase chain reaction (PCR), Western blotting, and immunohistochemistry in GBM (n = 26) and control (n = 11) brain tissue. The vascular pattern (VP) and microvascular density (MVD) were analyzed after laminin immunostaining. O6-Methylguanine-methyltransferase (MGMT) promoter methylation in GBM samples was detected by methylation-specific PCR.

RESULTS

The mRNA levels of Dll4, Jagged1, Notch1, Notch4, Hey1, Hey2, Hes1, and VEGF were 3.12-, 3.58-, 3.37-, 5.77-, 4.89-, 3.13-, 6.62-, and 32.57-fold elevated, respectively, in GBM samples, compared with the controls. Western blotting revealed a 4-, 3.7-, and 45.6-fold upregulation of Dll4, Notch1, and Hey1, respectively, accompanied by a downregulation of PTEN expression and an increase in the expression of p-Akt and VEGF. Immunostaining located the immunoreactivity of Dll4 and Notch1 in endothelial cells, microglia/macrophages, tumor cells, and astrocytes. Furthermore, the upregulation of Dll4-Notch signaling components was correlated to a low MVD and was potentially related to a classic VP, tumor edema, and MGMT promoter methylation.

CONCLUSIONS

The upregulation of Dll4-Notch signaling components was found in a subset of GBM samples and was associated with some angiogenic and clinical parameters. These findings highlight this signaling pathway as a potential therapeutic target for patients with GBM who show an activation of Dll4-Notch signaling.

APRIL binding to BCMA activates a JNK2-FOXO3-GADD45 pathway and induces a G2/M cell growth arrest in liver cells

The TNF superfamily ligands APRIL and BAFF bind with different affinity to two receptors, BCMA and TACI, and induce cell survival and/or proliferation, whereas BAFF also binds specifically to BAFFR. These molecules were considered specific for the immune system. Recently, however, they were also found in epithelial and mesenchymal noncancerous and cancerous tissues and cell lines. In this article, we report that hepatocellular carcinoma (HCC) cell lines HepG2 and Hep3B and HCC specimens express APRIL and BAFF and their receptors BCMA and BAFFR, but not TACI; APRIL/BCMA is enhanced in HCC, compared with normal liver tissue. In contrast to previous reports, APRIL binding to BCMA decreases cell proliferation by inducing G(2)/M cell cycle arrest, whereas BAFF has no effect on cell growth. HCC cells therefore represent a rare system in which these two ligands (APRIL and BAFF) exert a differential effect and may serve as a model for specific APRIL/BCMA actions. We show that the effect of APRIL is mediated via BCMA, which does not activate the classical NF-κB pathway, whereas it induces a novel signaling pathway, which involves JNK2 phosphorylation, FOXO3A activation, and GADD45 transcription. In addition, JNK2 mediates the phosphorylation of Akt, which is activated but does not participate in the antiproliferative effect of APRIL. Furthermore, transcriptome analysis revealed that APRIL modifies genes specifically related to cell cycle modulation, including MCM2/4/5/6, CDC6, PCNA, and POLE2. Our data, therefore, identify a novel APRIL/BCMA signaling pathway in HCC and suggest that APRIL could have a pleiotropic role in tumor biology.

Knockdown of a proliferation-inducing ligand (PRIL) suppresses the proliferation of gastric cancer cells

PURPOSE

PRIL (proliferation-inducing ligand) is a newly identified member of the tumor necrosis factor (TNF) family and modulates death ligand-induced apoptosis. Here, we investigated the effect of PRIL on cellular characteristics relating to tumor progression in human gastric cancer.

METHOD

Recombinant lentivirus containing APRIL siRNA was constructed and then infected MGC803 and SGC7901 gastric cancer cells. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] colony formation and cell cycle analysis were used to study the effect of APRIL knockdown on gastric cancer cell proliferation.

RESULTS

PRIL expression in lentivirus infected cells was significantly reduced as evidenced by quantitative real-time PCR. Cell viability and colony formation of MGC803 and SGC7901 cells were significantly hampered in PRIL knock-down cells. Moreover, the cell cycle was arrested at G2/M phase, elucidating the mechanism underlying the inhibitory effect of siRNA on cell proliferation.

CONCLUSIONS

Our study indicated that PRIL functions in promoting cell growth, and lentivirus-mediated PRIL gene knockdown might be a promising strategy in the treatment of gastric cancer.

Targeting of colorectal cancer growth, metastasis, and anti-apoptosis in BALB/c nude mice via APRIL siRNA

A proliferation-inducing ligand (APRIL) is overexpressed in most tumor cells and tissues, especially in tumors of the alimentary system, such as colorectal cancer (CRC), gastric cancer, and liver cancer. RNA interference (RNAi) has been proved to be a powerful tool for gene knockdown and holds great promise for the treatment of cancer. In this study, the efficacy of RNAi targeting APRIL was analyzed via relevant experiments on human CRC xenografted in BALB/c nude mice. Both the mRNA and protein levels of APRIL were examined after intratumoral injection of APRIL small interfering RNA (siRNA). Meanwhile, pathological tools were utilized to observe the alterations on the aspects of proliferation, metastasis, apoptosis and cellular necrosis by means of detecting proliferating cell nuclear antigen, Ki-67, MMP-2, MMP-9, TIMP-3, TIMP-4, Bcl-2, Bax and Bcl-xL of CRC. In addition, terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) and hematoxylin and eosin staining were also conducted to examine cell apoptosis and necrosis. It was found that grafted human colorectal tumor growth and metastasis were obviously inhibited while tumor cell apoptosis and necrosis were induced after in vivo APRIL siRNA injection into nude mice. The data indicated that silencing of the APRIL gene using RNAi may serve as a novel therapeutic strategy for treatment of CRC.

Molecular structure, expression analysis and functional characterization of APRIL (TNFSF 13) in goat (Capra hircus)

A proliferation-inducing ligand (APRIL) is an important member of the tumor necrosis factor (TNF) superfamily. In the present study, a novel cDNA was isolated from the spleen of goat by RT-PCR and designated as goat APRIL (gAPRIL). The open reading frame (ORF) of this cDNA covered 753bp, encoding a protein of 250 amino acids. Sequence comparison showed that gAPRIL contains a predicted transmembrane domain, a putative furin protease cleavage site, and two cysteine residues, which are the typical characteristics of TNF gene in mammals. The predicted three dimensional (3D) structure of soluble part of the gAPRIL (gsAPRIL) monomer analyzed by comparative protein modeling revealed that it is very similar to its counterparts. Real-time PCR analysis revealed that gAPRIL was constitutively expressed in various tissues. Recombinant gsAPRIL fused with NusA tag was efficiently produced in Escherichia coli BL21 (DE3) and then analyzed by the SDS-PAGE as well as western blot. Laser scanning confocal microscopy analysis showed gsAPRIL could bind to its receptors. In vitro, the MTT and flow cytometric methods revealed that purified gsAPRIL protein was not only able to promote survival/proliferation of goat splenocytes, but also able to stimulate survival/proliferation of mouse B cells. These results indicated that gAPRIL plays an important role in survival/proliferation of goat splenocytes and provided a basis for investigating its potential to be used as an immunoadjuvant for enhancing vaccine efficacy and as an immunotherapeutic in goats.

Role of the GNAS1 T393C polymorphism in patients with glioblastoma multiforme

The T393C polymorphism of the GNAS1 locus, which encodes the Gαs protein, has recently been found to be associated with patient outcome in various malignancies. We investigated the association between GNAS1 genotype and survival among patients suffering from glioblastoma multiforme (GBM). One hundred and sixty-two patients with GBM were retrospectively investigated. Inclusion criteria were availability of DNA and, for surviving patients, a follow-up of at least 24 months. The results were analysed based on clinical data, type of surgical intervention, adjuvant therapy, and 2-year survival. At the 2-year follow up, 79.6% of patients had died. Two-year survival rates were as follows: CC-homozygous patients, 15.8%; CT-heterozygous patients, 23.1%; and TT-homozygous patients, 18.2% (p = 0.461). Subgroup analysis revealed different 2-year survival rates in the group that underwent stereotactic biopsy, with 0% for CC-homozygous, 2.8% for CT-heterozygous, and 15.4% survival for TT-homozygous patients, but the differences were not statistically significant (p = 0.229). Our results indicate that there is no association between the GNAS1 T393C polymorphism and 2-year survival among patients with GBM.

Association of the CC genotype of the regulatory BCL2 promoter polymorphism (-938C>A) with better 2-year survival in patients with glioblastoma multiforme

OBJECT

Bcl-2 plays a key role in the downregulation of apoptosis and proliferation and leads to increased chemoresistance in glioblastoma multiforme (GBM). The authors investigated the role of a common regulatory single-nucleotide polymorphism (-938C>A), which is located in the inhibitory P2 promoter of BCL2.

METHODS

Data from 160 patients suffering from GBM were retrospectively evaluated. Study inclusion criteria consisted of available DNA and, in patients still alive, a follow-up of at least 24 months. Results were analyzed with respect to the basic clinical data, type of surgical intervention (gross-total resection [GTR] versus stereotactic biopsy [SB]), adjuvant therapy, MGMT promoter methylation, and survival at the 2-year follow-up.

RESULTS

At the 2-year follow-up, 127 (79.4%) of the 160 patients had died. Kaplan-Meier curves revealed a significantly higher rate of survival for homo- and heterozygous C-allele carriers (p = 0.031). In the GTR group, the survival rate was 47.1% for homozygous C-allele carriers, 32.0% for heterozygous C-allele carriers, and only 21.4% for homozygous A-allele carriers (p = 0.024). The SB group showed no genotype-dependent differences. Multivariable Cox regression revealed that the BCL2 (-938AA) genotype was an independent negative prognostic factor for 2-year survival in the GTR group according to the BCL2 (-938CC) genotype reference group (hazard ratio 2.50, 95% CI 1.14-5.48, p = 0.022).

CONCLUSIONS

These results suggested that the (-938C>A) polymorphism is a survival prognosticator as well as a marker for a high-risk group among patients with GBM who underwent GTR.

Therapeutic effects of TACI-Ig on rat with adjuvant arthritis

Transmembrane activator and calcium modulator and cyclophilin ligand interactor-immunoglobulin (TACI-Ig) is a human fusion protein that binds and neutralizes both B lymphocyte stimulator (BLyS), a cytokine shown to be a key regulator of B cell maturation, proliferation and survival, and a proliferation-inducing ligand (APRIL). Rat adjuvant arthritis (AA) is an experimental animal model of rheumatoid arthritis (RA), which is mainly dependent on T cells and neutrophil-mediated cytokine production. The purpose of the present study was to investigate the effects of TACI-Ig on rat AA. Rat AA was induced by intradermal injection of 0·1 ml complete Freund's adjuvant (CFA). TACI-Ig (0·7, 2·1 and 6·3 mg/kg), recombinant human tumour necrosis factor-α receptor (rhTNFR) : Fc (2·8 mg/kg) and IgG-Fc (6·3 mg/kg) were administered subcutaneously every other day from days 16 to 34 after immunization. Arthritis was evaluated by arthritis global assessment and swollen joint count (SJC). The ankle joint and spleen were harvested for histopathological examination. Spleen index and thymus index were calculated. The levels of BLyS, interleukin (IL)-17, interferon (IFN)-γ, IgG1, IgG2a and IgM in AA rat spleen were measured by enzyme-linked immunosorbent assay. Administration of TACI-Ig significantly reduced the arthritis global assessment and SJC, decreased spleen index and ameliorated histopathological manifestations of rat AA. Suppressing the levels of BLyS, IL-17, IFN-γ and Ig in AA rat spleen were observed after administration of TACI-Ig. These results showed that TACI-Ig significantly inhibited the degree of rat AA, and the inhibitory effects might be associated with its ability to reduce BLyS, proinflammatory cytokines and Ig levels in spleen.

Studies on preparation and photodynamic mechanism of chlorin P6-13,15-N-(cyclohexyl)cycloimide (Chlorin-H) and its antitumor effect for photodynamic therapy in vitro and in vivo

Photodynamic therapy (PDT) represents a promising method for treatment of cancerous tumors. The chemical and physical properties of used photosensitizer play key roles in the treatment efficacy. In this study, a novel photosensitizer, Chlorin-H [-13,15-N-(cyclohexyl)cycloimide] which displayed a characteristic long wavelength absorption peak at 698nm was synthesized. Following flash photolysis with 355nm laser, Chlorin-H is potent to react with O(2) and then produce (1)O(2). This finding indicates that Chlorin-H takes its effects through type II mechanism in PDT. Generally, Chlorin-H is localized in mitochondria and nucleus of cell. After light irradiation with 698nm laser, it can kill many types of cell, inhibit cell proliferation and colony formation, suppress cancer cell invasiveness and trigger apoptosis via the mitochondrial pathway in A549 cells in vitro. In addition, Chlorin-H-PDT can destroy A549 tumor in nude mice and a necrotic scab was formed eventually. The expression levels of many genes which regulated cell growth and apoptosis were determined by RT-PCR following Chlorin-H-PDT. The results showed that it either increased or decrease. Among which, the expression level of TNFSF13, a member of tumor necrosis factor superfamily, increased significantly. Silencing of TNFSF13 caused by RNA interference decreased the susceptibility of A549 cells to Chlorin-H-PDT. In general, Chlorin-H is an effective antitumor photosensitizer in vitro and in vivo and is worthy of further study as a new drug candidate. TNFSF13 will be an important molecular target for the discovery of new photosensitizers.

A proliferation-inducing ligand: a new biomarker for non-small cell lung cancer

To identify a proliferation-inducing ligand (APRIL) expression profile in tumor tissue and sputum of lung cancer, and evaluate the possibility of an assistant diagnosis of lung cancer by real-time fluorescence quantitative polymerase chain reaction (RTQ-PCR) in sputum as well, the authors analyzed the expression of APRIL mRNA in 75 tissue samples and 71 corresponding sputum samples of lung cancer by RTQ-PCR and analyzed their correlation. APRIL protein expression was also observed in tumor tissues by Western blot and immunohistochemistry. The expression analysis revealed APRIL expression was elevated in non-small cell lung cancer (NSCLC) and the expression of APRIL protein was located in the membrane and cytoplasm of tumor cells by immunohistochemiscal staining. Compared to benign pulmonary disease and healthy volunteers, the expression of APRIL mRNA in sputum of lung cancer was elevated (both P <. 001). When cut-off values for positivity were set at the mean + 2SD of mRNA expression in healthy volunteers, the positive rate for APRIL mRNA expression was 81.7% (58/71) in sputum samples of lung cancer, 3.2% (2/62) in benign pulmonary disease, and 1.5% (1/65) in healthy volunteers. The correlation was evident between the expression level of APRIL mRNA of tissue samples and that of sputum samples (P <. 001, r =. 702). These results support the possibility that the APRIL gene may play a key role in lung cancer, especially in NSCLC. The elevated expression level of APRIL mRNA in sputum of NSCLC suggested that APRIL mRNA may serve as an effective and convenient diagnostic biomarker for NSCLC.

APRIL is a novel clinical chemo-resistance biomarker in colorectal adenocarcinoma identified by gene expression profiling

BACKGROUND

5-Fluorouracil(5FU) and oral analogues, such as capecitabine, remain one of the most useful agents for the treatment of colorectal adenocarcinoma. Low toxicity and convenience of administration facilitate use, however clinical resistance is a major limitation. Investigation has failed to fully explain the molecular mechanisms of resistance and no clinically useful predictive biomarkers for 5FU resistance have been identified. We investigated the molecular mechanisms of clinical 5FU resistance in colorectal adenocarcinoma patients in a prospective biomarker discovery project utilising gene expression profiling. The aim was to identify novel 5FU resistance mechanisms and qualify these as candidate biomarkers and therapeutic targets.

METHODS

Putative treatment specific gene expression changes were identified in a transcriptomics study of rectal adenocarcinomas, biopsied and profiled before and after pre-operative short-course radiotherapy or 5FU based chemo-radiotherapy, using microarrays. Tumour from untreated controls at diagnosis and resection identified treatment-independent gene expression changes. Candidate 5FU chemo-resistant genes were identified by comparison of gene expression data sets from these clinical specimens with gene expression signatures from our previous studies of colorectal cancer cell lines, where parental and daughter lines resistant to 5FU were compared. A colorectal adenocarcinoma tissue microarray (n = 234, resected tumours) was used as an independent set to qualify candidates thus identified.

RESULTS

APRIL/TNFSF13 mRNA was significantly upregulated following 5FU based concurrent chemo-radiotherapy and in 5FU resistant colorectal adenocarcinoma cell lines but not in radiotherapy alone treated colorectal adenocarcinomas. Consistent with APRIL's known function as an autocrine or paracrine secreted molecule, stromal but not tumour cell protein expression by immunohistochemistry was correlated with poor prognosis (p = 0.019) in the independent set. Stratified analysis revealed that protein expression of APRIL in the tumour stroma is associated with survival in adjuvant 5FU treated patients only (n = 103, p < 0.001), and is independently predictive of lack of clinical benefit from adjuvant 5FU [HR 6.25 (95%CI 1.48-26.32), p = 0.013].

CONCLUSIONS

A combined investigative model, analysing the transcriptional response in clinical tumour specimens and cancers cell lines, has identified APRIL, a novel chemo-resistance biomarker with independent predictive impact in 5FU-treated CRC patients, that may represent a target for novel therapeutics.

Expression and purification of APRIL by auto-induction

APRIL (A proliferation-inducing ligand) is a newly-identified member of the tumor necrosis factor family that induces pleiotropic biological responses, including immunological responses, IgA class switch and cell growth. It is associated with multiple diseases such as cancer and autoimmune diseases. High levels of APRIL mRNA can be detected in transformed cell lines and several malignant tumors; heparin sulfate proteoglycans (HSPG) are also involved in the APRIL tumor cell proliferation induction response. The interaction of APRIL and HSPG occurs through an N-terminal basic region on APRIL. We successfully expressed recombinant APRIL using an auto-induction system in Escherichia coli. By using in situ cleavage, we generated the mature form of APRIL, comprising its N-terminal basic region, which has full biological activity: receptor binding capability and proliferation induction activity.

APRIL in B-cell malignancies and autoimmunity

A Proliferation Inducing Ligand (APRIL) was first identified as a cytokine expressed predominantly by tumour tissues and was not found in most normal tissues. The activity of this new cytokine, in terms of its ability to stimulate tumour cell proliferation in vivo, determined the catchy acronym of yet another TNF family cytokine: APRIL. Reports showing an association between APRIL and cancer have since been prolific, in particular, those showing a link with B cell malignancies. Evidence is accumulating that APRIL is also a player in several autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, and Sjoegren's syndrome. However, we now know that APRIL also plays an important role in the immune system and in lymphocyte biology. In this chapter we outline the physiological role of APRIL in immunity and describe what is known regarding the role of APRIL in B cell malignancies and autoimmune disease.

"APRIL hath put a spring of youth in everything": Relevance of APRIL for survival

A proliferation inducing ligand (APRIL or TALL-2 and TRDL-1) was first discovered as a cytokine over-expressed in many transformed cells and with the capacity to stimulate proliferation. APRIL was shown to bind two different receptors of the TNF receptor superfamily: B cell maturation antigen (BCMA) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), as well as heparan sulphate proteoglycans (HSPGs). APRIL has since been shown to play a physiological role in B cell biology, in particular the survival of plasma B cells in a specialized APRIL-rich niche. However, aberrant expression of APRIL and the subsequent activation of pro-survival pathways, is potentially the driving force for the survival of several B cell malignancies. APRIL has therefore become an important therapeutic target, but many questions regarding its mechanism of action still remain. It is for instance unclear what the exact physiological implications of the APRIL-HSPG interaction could be. Neither do we know the precise signals elicited by APRIL in normal or in malignant cells, and whether blocking these effects could provide real therapeutic gain in cancer patients. In this review we discuss the specific relevance of APRIL for cell survival, in terms of both its physiological role and its role in tumor biology, and highlight some of the key questions that will undoubtedly form the basis of future research in this field.

The BLyS family: toward a molecular understanding of B cell homeostasis

The B Lymphocyte Stimulator (BLyS) family of ligands and receptors regulates humoral immunity by controlling B lymphocyte survival and differentiation. Herein, we review the ligands and receptors of this family, their biological functions, and the biochemical processes through which they operate. Pre-immune B lymphocytes rely on BLyS signaling for their survival, whereas antigen experienced B lymphocytes generally interact more avidly with a homologous cytokine, A Proliferation Inducing Ligand (APRIL). The molecular basis for signaling via the three BLyS family receptors reveals complex interplay with other B lymphocyte signaling systems, affording the integration of selective and homeostatic processes. As our understanding of this system advances, molecular targets for manipulating humoral immunity in both health and disease should be revealed.

Bcl2L12-mediated inhibition of effector caspase-3 and caspase-7 via distinct mechanisms in glioblastoma

Glioblastoma multiforme (GBM) is a highly aggressive brain cancer that is characterized by the paradoxical features of intense apoptosis resistance yet a marked propensity to undergo necrosis. Bcl2L12 (for Bcl2-Like12) is a nuclear and cytoplasmic oncoprotein that is universally overexpressed in primary GBM and functions to block postmitochondrial apoptosis signaling by neutralizing effector caspase-3 and caspase-7 maturation. This postmitochondrial block in apoptosis engenders the alternate cell fate of cellular necrosis, thus providing a molecular explanation for GBM's classical features. Whereas Bcl2L12-mediated neutralization of caspase-7 maturation involves physical interaction, the mechanism governing Bcl2L12-mediated inhibition of caspase-3 activity is not known. The nuclear localization of Bcl2L12 prompted expression profile studies of primary astrocytes engineered to overexpress Bcl2L12. The Bcl2L12 transcriptome revealed a striking induction of the small heat shock protein alpha-basic-crystallin (alphaB-crystallin/HspB5), a link reinforced by robust alphaB-crystallin expression in Bcl2L12-expressing orthotopic glioma and strong coexpression of alphaB-crystallin and Bcl2L12 proteins in human primary GBMs. On the functional level, enforced alphaB-crystallin or Bcl2L12 expression enhances orthotopic tumor growth. Conversely, RNAi-mediated knockdown of alphaB-crystallin in Bcl2L12-expressing astrocytes and glioma cell lines with high endogenous alphaB-crystallin showed enhanced apoptosis, yet decreased necrotic cell death with associated increased caspase-3 but not caspase-7 activation. Mirroring this specific effect on effector caspase-3 activation, alphaB-crystallin selectively binds pro-caspase-3 and its cleavage intermediates in vitro and in vivo. Thus, alphaB-crystallin is a Bcl2L12-induced oncoprotein that enables Bcl2L12 to block the activation of both effector caspases via distinct mechanisms, thereby contributing to GBM pathogenesis and its hallmark biological properties.

Two related ligands of the TNF family, BAFF and APRIL, in rabbit: Molecular cloning, 3D modeling, and tissue distribution

B-cell activating factor belonging to the TNF family (BAFF) and a proliferation-inducing ligand (APRIL) are two related members of the TNF ligand superfamily. These two ligands and their receptors, also termed "the BAFF/APRIL system", play important immunological roles, especially in the B-cell arm of the immune system. This paper reports the cloning and expression analysis of these two cytokines in rabbit (Oryctolagus cuniculus) by homology cloning. The complete transcript of the rabbit BAFF was sequenced and contained 1457 bp, including an 873 bp open reading frame. The predicted protein of 290 aa revealed the presence of the BAFF family signature, the "Flap". The soluble mature part of rabbit BAFF (sBAFF) showed 75-92% sequence identity with mammalian and avian homologs. The full-length cDNA of rabbit APRIL contained 1030 bp of which 753 bp are the open reading frame. The conserved potential N-glycosylation site and the cysteine residues were found in both the two ligands. The predicted three dimensional (3D) structures of sBAFF and sAPRIL analyzed by comparative protein modeling reveal that they are very similar to the human counterparts. Real-time PCR analysis revealed that rabbit BAFF gene was predominantly expressed in the lymphoid tissues, such as spleen and thymus; while the APRIL mRNA was found to be relatively high in a wide range of tissues. These findings indicate that BAFF and APRIL in rabbit play similar roles as in human. It provides the basis for investigation on their roles in regulating B-cell development and immune responses in rabbit and also contributes to our understanding of the evolution of these two novel TNF ligands.

Characterization of TROY-expressing cells in the developing and postnatal CNS: the possible role in neuronal and glial cell development

A member of the tumor necrosis factor receptor superfamily, TROY, is expressed in the CNS of embryonic and adult mice. In the present study, we characterized TROY-expressing cells in the embryonic and postnatal forebrain. In the early embryonic forebrain, TROY was highly expressed in nestin-positive neuroepithelial cells and radial glial cells, but not in microtubule-associated protein 2-positive postmitotic neurons. During the late embryonic and postnatal development, expression of TROY was observed in radial glial cells and astrocytes, whereas its expression was not detected in neuronal lineage cells. In addition, TROY was exclusively expressed in Musashi-1-positive multipotent/glial progenitors in the postnatal subventricular zone. To investigate the functions of TROY in neural development, we overexpressed TROY in PC12 cells and established stably expressing cell clones. As expected, the signals from overexpressed TROY were constitutively transduced via the activation of the nuclear factor-kappaB and the c-Jun N-terminal kinase pathways in such clones. In addition, upregulation of negative basic helix-loop-helix transcription factors, HES-5 and Id2 proteins, was observed in the TROY-overexpressing clones. Interestingly, the overexpression of TROY in PC12 cells strongly inhibited nerve growth factor-induced neurite outgrowth with reduction of some markers of differentiated neurons, such as neurofilament 150 kDa and neuron-specific beta-tubulin. These findings suggest that the signaling from TROY regulates neuronal differentiation at least in part.

HIV-1 negatively affects the survival/maturation of cord blood CD34(+) hematopoietic progenitor cells differentiated towards megakaryocytic lineage by HIV-1 gp120/CD4 membrane interaction

To investigate the mechanisms involved in the human immunodeficiency virus type 1 (HIV-1)-related thrombocytopenia (TP), human umbilical cord blood (UCB) CD34(+) hematopoietic progenitor cells (HPCs) were challenged with HIV-1(IIIb) and then differentiated by thrombopoietin (TPO) towards megakaryocytic lineage. This study showed that HIV-1, heat-inactivated HIV-1, and HIV-1 recombinant gp120 (rgp120) activated apoptotic process of megakaryocyte (MK) progenitors/precursors and decreased higher ploidy MK cell fraction. All these inhibitory effects on MK survival/maturation and platelets formation were elicited by the interaction between gp120 and CD4 receptor on the cell membrane in the absence of HIV-1 productive infection. In fact, in our experimental conditions, HPCs were resistant to HIV-1 infection and no detectable productive infection was observed. We also evaluated whether the expression of specific cytokines, such as TGF-beta1 and APRIL, involved in the regulation of HPCs and MKs proliferation, was modulated by HIV-1. The specific protein and mRNA detection analysis, during TPO-induced differentiation, demonstrated that HIV-1 upregulates TGF-beta1 and downregulates APRIL expression through the CD4 engagement by gp120. Altogether, these data suggest that survival/differentiation of HPCs committed to MK lineage is negatively affected by HIV-1 gp120/CD4 interaction. This long-term inhibitory effect is also correlated to specific cytokines regulation and it may represent an additional mechanism to explain the TP occurring in HIV-1 patients.

Bcl2L12 inhibits post-mitochondrial apoptosis signaling in glioblastoma

Glioblastoma (GBM) is an astrocytic brain tumor characterized by an aggressive clinical course and intense resistance to all therapeutic modalities. Here, we report the identification and functional characterization of Bcl2L12 (Bcl2-like-12) that is robustly expressed in nearly all human primary GBMs examined. Enforced Bcl2L12 expression confers marked apoptosis resistance in primary cortical astrocytes, and, conversely, its RNA interference (RNAi)-mediated knockdown sensitizes human glioma cell lines toward apoptosis in vitro and impairs tumor growth with increased intratumoral apoptosis in vivo. Mechanistically, Bcl2L12 expression does not affect cytochrome c release or apoptosome-driven caspase-9 activation, but instead inhibits post-mitochondrial apoptosis signaling at the level of effector caspase activation. One of Bcl2L12's mechanisms of action stems from its ability to interact with and neutralize caspase-7. Notably, while enforced Bcl2L12 expression inhibits apoptosis, it also engenders a pronecrotic state, which mirrors the cellular phenotype elicited by genetic or pharmacologic inhibition of post-mitochondrial apoptosis molecules. Thus, Bcl2L12 contributes to the classical tumor biological features of GBM such as intense apoptosis resistance and florid necrosis, and may provide a target for enhanced therapeutic responsiveness of this lethal cancer.

The role of the BAFF/APRIL system on T cell function

BAFF is a key factor controlling B cell survival and maturation and its over-expression promotes B cell-mediated autoimmune disorders and participates in the progression of B cell lymphomas. Yet, BAFF and a related ligand APRIL are expressed by T lymphocytes and modulate their functions. BAFF and APRIL promote T cell activation and survival. BAFF over-expression in transgenic (Tg) mice enhances T helper 1 (Thl)-driven delayed-type hypersensitivity (DTH), but inhibits T helper 2 (Th2) cell-mediated allergic airway inflammation in mice. Some of these effects are also dependent on BAFF-induced modification of the B cell compartment. Therefore, direct BAFF/APRIL signalling in T cells and/or T cell modulation in response to a BAFF-modified B cell compartment may play an important role in inflammation and immunomodulation.

BLyS receptor signatures resolve homeostatically independent compartments among naïve and antigen-experienced B cells

The BLyS family of receptors includes two cytokines, BLyS and APRIL; and three receptors, BR3, BCMA and TACI. Together, these regulate the size and composition of peripheral B cell pools. The multiplicity of ligand-receptor sets, in conjunction with differential receptor expression, alternative binding partners and disparate downstream signaling characteristics, affords the potential to establish independently regulated homeostatic niches among primary and antigen-experienced B cell subsets. Thus, BLyS signaling via BR3 is the dominant homeostatic regulator of primary B cell pools, whereas APRIL interactions with BCMA likely govern memory B cell populations. Short-lived antibody forming cell populations and their proliferating progenitors express a TACI-predominant signature. Further, within each niche, relative fitness to compete for available cytokine is determined by exogenous inputs via adaptive and innate receptor systems, affording intramural hierarchies that determine clonotype composition.

Characterization of TROY/TNFRSF19/TAJ-expressing cells in the adult mouse forebrain

A member of the tumor necrosis factor receptor superfamily (TNFRSF), TROY/TNFRSF19/TAJ, is highly expressed in the brain of adult mice. Northern blot analysis using mRNA taken from regions of the adult CNS showed the expression of TROY in all regions examined, including the olfactory bulb, cerebral cortex, striatum, and hippocampus. In situ hybridization and immunohistochemistry revealed that TROY mRNA and protein were strongly expressed in the rostral migratory stream (RMS) and subventricular zone (SVZ) of adult mice. In the adult SVZ, some glial fibrillary acidic protein (GFAP)-positive cells (type B cells) are thought to be multipotent neural stem cells. These type B cells divide slowly and generate epidermal growth factor receptor (EGFR)-positive transit-amplifying precursor cells (type C cells) in the presence of epidermal growth factor (EGF). Type C cells give rise to neuron-specific class III beta-tubulin (TuJ1)-positive neuroblasts (type A cells) that migrate to the olfactory bulb along the RMS. TROY-expressing cells were GFAP-positive, EGFR-positive, and TuJ1-negative in the adult SVZ. From these findings, TROY appears to be expressed in type B and type C cells, but not in type A cells, which was supported by immunoelectron microscopy. In addition, TROY was expressed in GFAP-positive astrocytes of the various regions, such as the cerebral cortex, striatum, and hippocampus. Thus, TROY was expressed in uncommitted precursor cells and astroglial lineage cells, suggesting that TROY plays some roles in the regulation of gliogenesis in the adult CNS.

The source of APRIL up-regulation in human solid tumor lesions

Abundant mRNA expression for a proliferation-inducing ligand (APRIL) from tumor necrosis factor (TNF) family is observed in many solid tumors. Here, we analyzed in situ the cellular source of APRIL in human solid tumors with anti-APRIL antibodies. In most cases, neutrophils present in the tumor stroma constituted the main source of APRIL. In cutaneous lesions such as melanoma or basal cell carcinoma, tumor-adjacent keratinocytes also produced APRIL. APRIL production by tumor cells themselves was a rare event, only observed in urothelial bladder cancer and squamous cell carcinoma. Detailed analysis revealed that APRIL dissociated from producing cells, and secreted APRIL was retained in the tumor lesions. A direct binding onto tumor cells via heparan sulfate proteoglycans (HSPG) was observed in in vitro experiments and confirmed in situ. Taken together, our analysis indicates a potential role for HSPG/APRIL interactions in the development of solid tumors.

An APRIL to remember: novel TNF ligands as therapeutic targets

Since their discovery in 1998, the two TNF family members APRIL and BLyS/BAFF have received increasing attention. In addition to regulating normal B-cell development and immune responses, these molecules might be crucial in a diverse set of diseases, including autoimmunity and cancer. Although more has been published about the general biology of BLyS/BAFF than that of APRIL, many recent articles have described novel APRIL biology. Here we focus on APRIL, exploring its normal and pathological functions, and comparing the therapeutic molecules currently under development that target BLyS/BAFF alone, or APRIL and BLyS/BAFF together.