Endogenous neurotrophins and Trk signaling in diffuse large B cell lymphoma cell lines are involved in sensitivity to rituximab-induced apoptosis

Nerve Growth Factor and the Role of Inflammation in Tumor Development

Nerve growth factor (NGF) plays a dual role both in inflammatory states and cancer, acting both as a pro-inflammatory and oncogenic factor and as an anti-inflammatory and pro-apoptotic mediator in a context-dependent way based on the signaling networks and its interaction with diverse cellular components within the microenvironment. This report aims to provide a summary and subsequent review of the literature on the role of NGF in regulating the inflammatory microenvironment and tumor cell growth, survival, and death. The role of NGF in inflammation and tumorigenesis as a component of the inflammatory system, its interaction with the various components of the respective microenvironments, its ability to cause epigenetic changes, and its role in the treatment of cancer have been highlighted in this paper.

Nerve Growth Factor and Autoimmune Diseases

NGF plays a crucial immunomodulatory role and increased levels are found in numerous tissues during autoimmune states. NGF directly modulates innate and adaptive immune responses of B and T cells and causes the release of neuropeptides and neurotransmitters controlling the immune system activation in inflamed tissues. Evidence suggests that NGF is involved in the pathogenesis of numerous immune diseases including autoimmune thyroiditis, chronic arthritis, multiple sclerosis, systemic lupus erythematosus, mastocytosis, and chronic granulomatous disease. Furthermore, as NGF levels have been linked to disease severity, it could be considered an optimal early biomarker to identify therapeutic approach efficacy. In conclusion, by gaining insights into how these molecules function and which cells they interact with, future studies can devise targeted therapies to address various neurological, immunological, and other disorders more effectively. This knowledge may pave the way for innovative treatments based on NGF manipulation aimed at improving the quality of life for individuals affected by diseases involving neurotrophins.

BDNF-loaded PDADMAC-heparin multilayers: a novel approach for neuroblastoma cell study

Biomaterial science has contributed tremendously to developing nanoscale materials for delivering biologically active compounds, enhancing protein stability, and enabling its therapeutic use. This paper presents a process of formation of polyelectrolyte multilayer (PEM) prepared by sequential adsorption of positively charged polydiallyldimethylammonium chloride (PDADMAC) and negatively charged heparin sodium salt (HP), from low polyelectrolyte concentration, on a solid substrate. PEM was further applied as a platform for the adsorption of a brain-derived growth factor (BDNF), which is a protein capable of regulating neuronal cell development. The multilayers containing BDNF were thoroughly characterized by electrokinetic (streaming potential measurements, SPM) and optical (optical waveguide lightmode spectroscopy, OWLS) techniques. It was found that BDNF was significantly adsorbed onto polyelectrolyte multilayers terminated by HP under physiological conditions. We further explore the effect of established PEMs in vitro on the neuroblastoma SH-SY5Y cell line. An enzyme-linked immunosorbent assay (ELISA) confirmed that BDNF was released from multilayers, and the use of the PEMs intensified its cellular uptake. Compared to the control, PEMs with adsorbed BDNF significantly reduced cell viability and mitochondrial membrane polarization to as low as 72% and 58%, respectively. HPLC analysis showed that both PDADMAC-terminated and HP-terminated multilayers have antioxidative properties as they almost by half decreased lipid peroxidation in SH-SY5Y cells. Finally, enhanced formation of spheroid-like, 3D structures was observed by light microscopy. We offer a well-characterized PEM with antioxidant properties acting as a BDNF carrier, stabilizing BDNF and making it more accessible to cells in an inhomogeneous, dynamic, and transient in vitro environment. Described multilayers can be utilized in future biomedical applications, such as boosting the effect of treatment by selective anticancer as adjuvant therapy, and in biomedical research for future development of more precise neurodegenerative disease models, as they enhance cellular 3D structure formation.

Sortilin deletion in the prefrontal cortex and hippocampus ameliorates depressive-like behaviors in mice via regulating ASM/ceramide signaling

Major depressive disorder (MDD) is a common psychiatric disorder characterized by persistent mood despondency and loss of motivation. Although numerous hypotheses have been proposed, the possible pathogenesis of MDD remains unclear. Several recent studies show that a classic transporter protein, sortilin, is closely associated with depression. In the present study, we investigated the role of sortilin in MDD using a well-established rodent model of depression. Mice were subjected to chronic unpredictable mild stress (CUMS) for 6 weeks. We showed that the expression levels of sortilin were significantly increased in the prefrontal cortex and hippocampus of CUMS mice. The depressive-like behaviors induced by CUMS were alleviated by specific knockdown of sortilin in the prefrontal cortex and hippocampus. We revealed that sortilin facilitated acid sphingomyelinase (ASM)/ceramide signaling, which activated RhoA/ROCK2 signaling, ultimately causing the transformation of dendritic spine dynamics. Specific overexpression of sortilin in the prefrontal cortex and hippocampus induced depressive-like behaviors, which was mitigated by injection of ASM inhibitor SR33557 (4 µg/μL) into the prefrontal cortex and hippocampus. In conclusion, sortilin knockdown in the prefrontal cortex and hippocampus plays an important role in ameliorating depressive-like behavior induced by CUMS, which is mainly evidenced by decreasing the trafficking of ASM from the trans-Golgi network to the lysosome and reducing the ceramide levels. Our results provide a new insight into the pathology of depression, and demonstrate that sortilin may be a potential therapeutic target for MDD.

CD20 expression, TrkB activation and functional activity of diffuse large B cell lymphoma-derived small extracellular vesicles

BACKGROUND

Small extracellular vesicles (sEVs) including exosomes, carrying the CD20, could be involved in immunotherapy resistance in diffuse large B cell lymphoma (DLBCL). We have reported endogenous brain-derived neurotrophic factor/TrkB (tropomyosin-related kinase B) survival axis in DLBCL. Here, we performed a comparative study of sEV production by germinal centre B cell (GCB) and activated B cell (ABC)-DLBCL cell lines, and analysed TrkB activation on this process.

METHODS

GCB (SUDHL4 and SUDHL6) and ABC (OCI-LY3, OCI-LY10 and U2932) cell lines were used. sEVs were characterised using nanoparticle tracking analysis technology and western blot. CD20 content was also analysed by enzyme-linked immunoassay, and complement-dependent cytotoxicity of rituximab was investigated. 7,8-Dihydroxyflavone (7,8-DHF) was used as a TrkB agonist. In vivo role of sEVs was evaluated in a xenograft model.

RESULTS

sEVs production varied significantly between DLBCL cells, independently of subtype. CD20 level was consistent with that of parental cells. Higher CD20 expression was found in sEVs after TrkB activation, with a trend in increasing their concentration. sEVs determined in vitro and in vivo protection from rituximab, which seemed CD20 level-dependent; the protection was enhanced when sEVs were produced by 7,8-DHF-treated cells.

CONCLUSIONS

DLBCL-derived sEVs have the differential capacity to interfere with immunotherapy, which could be enhanced by growth factors like neurotrophins. Evaluating the sEV CD20 level could be useful for disease monitoring.

Brain-derived neurotrophic factor in hematological malignancies: From detrimental to potentially beneficial

Emerging studies have highlighted brain-derived neurotrophic factor (BDNF), a neuronal growth factor abundant in the peripheral blood, and its tyrosine kinase receptor TRKB, as onco-genes and proteins that support the survival of malignant hematological cells. In contrast, other researchers reported on a favorable association between BDNF blood levels and prognosis, chemotherapy response and neurological side effects in patients with hematological malignancies. Here, we review the accumulated data regarding the expression of BDNF and its receptors in normal hematopoietic and lymphatic cells and tissue. In addition, in-vitro experiments, animal models and human sample studies that investigated the role of BDNF and its receptors in hematological malignancies are discussed. Finally, directions for future research aimed at revealing the mechanisms underlying the protective effect of BDNF in patients with these diseases are suggested.

Overexpression of sortilin is associated with 5-FU resistance and poor prognosis in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer worldwide. Even if 5-fluorouracil (5-FU) is used as the first-line chemotherapeutic drug, responsiveness is only 20-30%. Acquired resistance to 5-FU contributes to both poor patient prognosis and relapse, emphasizing the need to identify biomarkers. Sortilin, a vacuolar protein sorting 10 protein (Vps10p), implicated in protein trafficking, is over expressed in CRC cell lines cultured 72 hours in presence of 5-FU. This overexpression was also observed in 5-FU-resistant cells derived from these cell lines as well as in CRC primary cultures (or patients derived cell lines). A significantly higher expression of sortilin was observed in vivo, in 5-FU-treated tumours engrafted in Nude mice, as compared with non-treated tumour. A study of transcriptional regulation allowed identifying a decrease in ATF3 expression, as an explanation of sortilin overexpression following 5-FU treatment. In silico analysis revealed SORT1 expression correlation with poor prognosis. Moreover, sortilin expression was found to be positively correlated with CRC tumour grades. Collectively, our findings identify sortilin as a potential biomarker of 5-FU resistance associated with poor clinical outcomes and aggressiveness in CRC. As a new prognostic factor, sortilin expression could be used to fight against CRC.

miRNA signature associated with R-CHOP refractoriness in patients diagnosed with diffuse large B cell lymphoma

Refractoriness remains as one of the challenges in patients with lymphoma under chemotherapy, and among biological regulators in cells driving this type of response are microRNAs (miRNAs). Different genes are constantly turned on or off according to the miRNAs expression profiles affecting the drug response in patients and their stability in serum and plasma makes them potential prognostic biomarkers in several diseases. Here we described a profile of miRNAs in plasma of diffuse large B cell lymphoma (DLBCL) patients. miRNA expression arrays were carried using pre-treatment plasma samples of sixteen patients, followed by a comparison between the responder and the non-responders. After six cycles of R–CHOP treatment, twelve out of sixteen patients were clinically diagnosed with complete response while in four patients no clinical response was observed. Between these groups, a signature of fifteen differential expressed miRNAs was found. The circulating miRNAs in plasma of patients with no response were related to the drug resistance in other types of cancer, by targeting genes involved in cell proliferation and apoptosis, among other cell processes.

BDNF belongs to the nurse-like cell secretome and supports survival of B chronic lymphocytic leukemia cells

Evading apoptosis and sustained survival signaling pathways are two central hallmarks of B-cell chronic lymphocytic leukemia (B-CLL) cells. In this regard, nurse-like cells (NLC), the monocyte-derived type 2 macrophages, deliver stimulatory signals via B-cell activating factor (BAFF), a proliferation-inducing ligand (APRIL), and the C-X-C Motif Chemokine Ligand 12 (CXCL12). Previously, we demonstrated that brain-derived neurotrophic factor (BDNF) protects B-CLL cells from spontaneous apoptosis by activating the oncogenic complex NTSR2-TrkB (neurotensin receptor 2-tropomyosin-related kinase receptor B), only overexpressed in B-CLL cells, inducing anti-apoptotic protein Bcl-2 (B-cell lymphoma 2) expression and Src kinase survival signaling pathways. Herein, we demonstrate that BDNF belongs to the NLC secretome and promotes B-CLL survival. This was demonstrated in primary B-CLL co-cultured with their autologous NLC, compared to B-CLL cells cultured alone. Inhibition of BDNF in co-cultures, enhances B-CLL apoptosis, whereas its exogenous recombinant activates pro-survival pathways in B-CLL cultured alone (i.e. Src activation and Bcl-2 expression), at a higher level than those obtained by the exogenous recombinant cytokines BAFF, APRIL and CXCL12, the known pro-survival cytokines secreted by NLC. Together, these results showed that BDNF release from NLC trigger B-CLL survival. Blocking BDNF would support research strategies against pro-survival cytokines to limit sustained B-CLL cell survival.

Serum brain-derived neurotrophic factor (BDNF) concentration predicts polyneuropathy and overall survival in multiple myeloma patients

Brain-derived neurotrophic factor (BDNF) is a protein with a potent influence on several aspects of neuronal and blood vessel functions. However, its prognostic potential and functional role in multiple myeloma (MM) remain largely unknown. In this study, we investigated the influence of BDNF on the risk of chemotherapy-induced peripheral neuropathy (CIPN) and clinical outcome. Study group consisted of 91 newly-diagnosed MM patients treated with bortezomib and/or thalidomide-based chemotherapy. Detection of BDNF in serum was performed using ELISA. Polyneuropathy was assessed according to the CTCAE Criteria v5. We observed that BDNF concentration correlated with the severity of polyneuropathy (P = 0·0463). Higher BDNF values were noted in patients who responded to treatment (P = 0·0326), and BDNF proved to be a useful marker to predict lack of response after eight cycles of treatment (sensitivity - 100%, specificity - 61·5%, P = 0·0142). Moreover this marker showed significant diagnostic usefulness in diagnosis of CIPN (sensitivity - 76%, specificity - 71·43%; area under the curve (AUC)= 0·77, 95%, confidence interval (CI): 0·64-0·88; P < 0·0001). Low BDNF was an independent, unfavourable prognostic factor associated with reduced overall survival (OS) (hazard ratio (HR) = 2·79, P = 0·0470). In conclusion, BDNF level may play a prognostic role and constitute a useful biomarker in predicting CIPN in MM patients.

Identification of Circulating Serum Multi-MicroRNA Signatures in Human DLBCL Models

There remains a need to identify new sensitive diagnostic and predictive blood-based platforms in lymphoma. We previously discovered a novel circulating microRNA (miRNA) signature in a Smurf2-deficient mouse model that spontaneously develops diffuse large B-cell lymphoma (DLBCL). Herein, we investigated this 10-miRNA signature (miR-15a, let-7c, let-7b, miR-27a, miR-10b, miR-18a, miR-497, miR-130a, miR24, and miR-155) in human lymphoma cell lines, mice engrafted with patient-derived xenografts (PDXs), and DLBCL patient serum samples leveraging systems biology analyses and droplet digital PCR (ddPCR) technology. Overall, 90% of the miRNAs were enriched in PDX DLBCL models and human lymphoma cell lines. Circulating miRNAs from the serum of 86 DLBCL patients were significantly increased compared with healthy controls and had similar patterns to the murine models. Strikingly, miRNAs were identified up to 27-fold higher levels in the serum of PDX-bearing mice and human patients compared with lymphoma cell lysates, suggesting a concentration of these factors over time within sera. Using cut-points from recursive partitioning analysis, we derived a 5-miRNA signature (let-7b, let-7c, miR-18a, miR-24, and miR-15a) with a classification rate of 91% for serum from patients with DLBCL versus normal controls. In addition, higher levels of circulating let-7b miRNA were associated with more advanced stage disease (i.e., III-IV vs. I-II) in DLBCL patients and higher levels of miR-27a and miR-24 were associated with MYC rearrangement. Taken together, circulating multi-miRNAs were readily detectable in pre-clinical cell line and human lymphoma models as well as in DLBCL patients where they appeared to distinguish clinico-pathologic subtypes and disease features.

Prohibitin (PHB) expression is associated with aggressiveness in DLBCL and flavagline-mediated inhibition of cytoplasmic PHB functions induces anti-tumor effects

BACKGROUND

Diffuse large B-cell lymphomas (DLBCLs) are aggressive lymphomas accounting for approximately a third of non-Hodgkin lymphomas. Prohibitin 1 (PHB1) and prohibitin 2 (PHB2) are scaffold proteins that promote mitochondria homeostasis and consequently cell survival, but biological functions of cytoplasmic PHBs remain largely unknown in DLBCL.

METHODS

PHB expression was analyzed in 82 DLBCL biopsies and five DLBCL cell lines by immunohistochemistry (IHC) and Western blotting. Pharmacological inhibition of PHB using the synthetic flavagline FL3 was realized in vitro to gain insight PHB cellular functions. Effects of FL3 on DLBCL cell line viability, apoptosis, C-Raf-ERK-MNK-eIF4E signaling pathway and eIF4F complex formation and activity were evaluated by XTT assay, annexin V-FITC/PI dual staining and Western blotting respectively. Subcutaneous DLBCL xenograft model in SCID mice was also performed to determine in vivo FL3 effect.

RESULTS

As in DLBCL cell lines, PHB1 and PHB2 were expressed in germinal center B-cell-like (GCB) and activated B-cell-like (ABC) subtypes. In patient samples, high PHB levels were associated with higher serum LDH (PHB1 and PHB2), IPIaa (PHB2), and Ki-67 (PHB2) expression. Higher PHB1 expression tends to be associated with shorter event-free survival (EFS) in patients, especially in male patients. FL3 induced apoptosis of DLBCL cell lines that was associated with inhibition of the ERK-MNK-eIF4E signaling pathway, including aggressive double/triple-hit DLBCL cell lines. This resulted in altered eIF4F complex formation and activity leading to a reduction of Bcl-2 and c-Myc expression levels. Moreover, FL3 strongly downregulated DLBCL cellular levels of Akt protein and AKT mRNA. FL3 antitumor activity was also confirmed in vivo in a murine xenograft model.

CONCLUSION

Our data indicate that PHB overexpression is associated with markers of tumor aggressiveness in DLBCL, and that targeting PHBs may be a therapeutic option, notably in aggressive subtypes.

Neurotensin receptor type 2 protects B-cell chronic lymphocytic leukemia cells from apoptosis

B-cell chronic lymphocytic leukemia (B-CLL) cells are resistant to apoptosis, and consequently accumulate to the detriment of normal B cells and patient immunity. Because current therapies fail to eradicate these apoptosis-resistant cells, it is essential to identify alternative survival pathways as novel targets for anticancer therapies. Overexpression of cell-surface G protein-coupled receptors drives cell transformation, and thus plays a critical role in malignancies. In this study, we identified neurotensin receptor 2 (NTSR2) as an essential driver of apoptosis resistance in B-CLL. NTSR2 was highly expressed in B-CLL cells, whereas expression of its natural ligand, neurotensin (NTS), was minimal in both B-CLL cells and patient plasma. Surprisingly, NTSR2 remained in a constitutively active phosphorylated state, caused not by a mutation-induced gain-of-function but rather by an interaction with the oncogenic tyrosine kinase receptor TrkB. Functional and biochemical characterization revealed that the NTSR2-TrkB interaction acts as a conditional oncogenic driver requiring the TrkB ligand brain-derived neurotrophic factor (BDNF), which unlike NTS is highly expressed in B-CLL cells. Together, NTSR2, TrkB and BDNF induce autocrine and/or paracrine survival pathways that are independent of mutation status and indolent or progressive disease course. The NTSR2-TrkB interaction activates survival signaling pathways, including the Src and AKT kinase pathways, as well as expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL. When NTSR2 was downregulated, TrkB failed to protect B-CLL cells from a drastic decrease in viability via typical apoptotic cell death, reflected by DNA fragmentation and Annexin V presentation. Together, our findings demonstrate that the NTSR2-TrkB interaction plays a crucial role in B-CLL cell survival, suggesting that inhibition of NTSR2 represents a promising targeted strategy for treating B-CLL malignancy.

Uncovering the role of brain-derived neurotrophic factor/tyrosine kinase receptor B signaling in head and neck malignancies

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors that was first known as responsible for sustain the growth, function, and plasticity of neural cells. BDNF exerts its effects by binding to the tyrosine kinase receptor B (TrkB). The BDNF/TrkB axis has been reported to be overexpressed in several neurogenic and non-neurogenic tumors. Its higher expression was associated with a poor prognosis to patients affected by different human malignancies, tumor growth, invasion, and metastasis; epithelial-mesenchymal transition and resistance to chemotherapy. BDNF/TrkB represent promising targets to the development of novel anticancer therapies. Some clinical trials are currently evaluating the efficacy of Trk protein-target drugs in different types of solid tumors. To date, few groups have evaluated the DNF/TrkB pathway in head and neck malignancies. The aims of this study were to review the literature concerning the role of BDNF/TrkB activation in head and neck squamous cell carcinoma and malignant salivary gland tumors and to discuss future perspectives of BDNF/TrkB-target therapy.

TrkA is a binding partner of NPM-ALK that promotes the survival of ALK+ T-cell lymphoma

Nucleophosmin‐anaplastic lymphoma kinase‐expressing (NPM‐ALK⁺) T‐cell lymphoma is an aggressive neoplasm that is more commonly seen in children and young adults. The pathogenesis of NPM‐ALK⁺ T‐cell lymphoma is not completely understood. Wild‐type ALK is a receptor tyrosine kinase that is physiologically expressed in neural tissues during early stages of human development, which suggests that ALK may interact with neurotrophic factors. The aberrant expression of NPM‐ALK results from a translocation between the ALK gene on chromosome 2p23 and the NPM gene on chromosome 5q35. The nerve growth factor (NGF) is the first neurotrophic factor attributed to non‐neural functions including cancer cell survival, proliferation, and metastasis. These functions are primarily mediated through the tropomyosin receptor kinase A (TrkA). The expression and role of NGF/TrkA in NPM‐ALK⁺ T‐cell lymphoma are not known. In this study, we tested the hypothesis that TrkA signaling is upregulated and sustains the survival of this lymphoma. Our data illustrate that TrkA and NGF are expressed in five NPM‐ALK⁺ T‐cell lymphoma cell lines and TrkA is expressed in 11 of 13 primary lymphoma tumors from patients. In addition, we found evidence to support that NPM‐ALK and TrkA functionally interact. A selective TrkA inhibitor induced apoptosis and decreased cell viability, proliferation, and colony formation of NPM‐ALK⁺ T‐cell lymphoma cell lines. These effects were associated with downregulation of cell survival regulatory proteins. Similar results were also observed using specific knockdown of TrkA in NPM‐ALK⁺ T‐cell lymphoma cells by siRNA. Importantly, the inhibition of TrkA signaling was associated with antitumor effects in vivo, because tumor xenografts in mice regressed and the mice exhibited improved survival. In conclusion, TrkA plays an important role in the pathogenesis of NPM‐ALK⁺ T‐cell lymphoma, and therefore, targeting TrkA signaling may represent a novel approach to eradicate this aggressive neoplasm.

Nerve growth factor & TrkA as novel therapeutic targets in cancer

In the past 20years, nerve growth factor (NGF) and its receptors TrkA & p75NTR were recognized to be overexpressed in the overwhelming majority of human solid cancers. Recent studies discovered the presence of overactive TrkA signaling due to TrkA rearrangements or TrkA fusion products in frequent cancers like colorectal cancer, thyroid cancer, or acute myeloid leukemia. Thus, targeting TrkA/NGF via selective small-molecule-inhibitors or antibodies has gained enormous attention in the drug discovery sector. Clinical studies on the anti-cancer impact of NGF-blocking antibodies are likely to be accelerated after the recent removal of clinical holds on these agents by regulatory authorities. Based on these current developments, the present review provides not only a broad overview of the biological effects of NGF-TrkA-p75NTR on cancer cells and their microenvironment, but also explains why NGF and its receptors are going to evoke major interest as promising therapeutic anti-cancer targets in the coming decade.

Tropomyosin-related kinase B/brain derived-neurotrophic factor signaling pathway as a potential therapeutic target for colorectal cancer

Colorectal cancer (CRC) is the second most common cause of cancer-related death in western countries. Approximately one-quarter of newly diagnosed patients for CRC have metastases, and a further 40%-50% experience disease recurrence or develop metastases after all standard therapies. Therefore, understanding the molecular mechanisms involved in the progression of CRC and subsequently developing novel therapeutic targets is crucial to improve management of CRC and patients’ long-term survival. Several tyrosine kinase receptors have been implicated in CRC development, progression and metastasis, including epidermal growth factor receptor (EGFR) and vascular EGFR. Recently, tropomyosin-related kinase B (TrkB), a tyrosine kinase receptor, has been reported in CRC and found to clearly exert several biological and clinical features, such as tumor cell growth and survival in vitro and in vivo, metastasis formation and poor prognosis. Here we review the significance of TrkB and its ligand brain derived-neurotrophic factor in CRC. We focus on their expression in CRC tumor samples, and their functional roles in CRC cell lines and in in vivo models. Finally we discuss therapeutic approaches that can lead to the development of novel therapeutic agents for treating TrkB-expressing CRC tumors.

Neurotrophins and B-cell malignancies

Neurotrophins and their receptors act as important proliferative and pro-survival factors in a variety of cell types. Neurotrophins are produced by multiple cell types in both pro- and mature forms, and can act in an autocrine or paracrine fashion. The p75(NTR) and Trk receptors can elicit signalling in response to the presence or absence of their corresponding neurotrophin ligands. This signalling, along with neurotrophin and receptor expression, varies between different cell types. Neurotrophins and their receptors have been shown to be expressed by and elicit signalling in B lymphocytes. In general, most neurotrophins are expressed by activated B-cells and memory B-cells. Likewise, the TrkB95 receptor is seen on activated B-cells, while TrkA and p75(NTR) are expressed by both resting and active B-cells as well as memory B-cells. Nerve growth factor stimulates B-cell proliferation, memory B-cell survival, antibody production and CD40 expression. Brain-derived neurotrophic factor is involved in B-cell maturation in the bone marrow through TrkB95. Overall neurotrophins and their receptors have been shown to be involved in B-cell proliferation, development, differentiation, antibody secretion and survival. As well as expression and activity in healthy B-cells, the neurotrophins and their receptors can contribute to B-cell malignancies including acute lymphoblastic leukaemia, diffuse large B-cell lymphoma, Burkitt's lymphoma and multiple myeloma. They are involved in B-cell malignancy survival and potentially in drug resistance.

Anti-apoptotic role and clinical relevance of neurotrophins in diffuse large B-cell lymphomas

Background:

Diffuse large B-cell lymphoma (DLBCL) is a fatal malignancy that needs to identify new targets for additional therapeutic options. This study aimed to clarify the clinical and biological significance of endogenous neurotrophin (nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF)) in DLBCL biopsy samples and cell lines.

Methods:

We analysed expression of NGF, BDNF, and their receptors (Trk, p75^NTR) in 51 biopsies and cell lines by immunohistochemistry, immunofluorescence, and western blotting. To investigate the biological role of BDNF/TrkB/p75^NTR axis, effects of neurotrophin signalling inhibition were determined on tumour cell survival and vascular endothelial growth factor (VEGF) secretion. The pharmacological pan-Trk inhibitor K252a was used for in vitro and in vivo studies.

Results:

A BDNF/TrkB axis was expressed in all biopsies, which was independent of the germinal centre B-cell (GCB)/non-GCB profile. p75^NTR, TrkB, and BDNF tumour scores were significantly correlated and high NGF expression was significantly associated with MUM1/IRF4, and the non-GCB subtype. Diffuse large B-cell lymphoma cell lines co-expressed neurotrophins and their receptors. The full-length TrkB receptor was found in all cell lines, which was also phosphorylated at Tyr-817. p75^NTR was associated to Trk and not to its cell death co-receptor sortilin. In vitro, inhibition of neurotrophin signalling induced cell apoptosis. K252a caused cell apoptosis, decreased VEGF secretion, and potentiated rituximab effect, notably in less rituximab-sensitive cells. In vivo, K252a significantly reduced tumour growth and potentiated the effects of rituximab in a GCB-DLBCL xenograft model.

Conclusions:

This work argues for a pro-survival role of endogenous neurotrophins in DLBCLs and inhibition of Trk signalling might be a potential treatment strategy for rituximab resistant subgroups.

Inhibition of Oncogenic Transcription Factor REL by the Natural Product Derivative Calafianin Monomer 101 Induces Proliferation Arrest and Apoptosis in Human B-Lymphoma Cell Lines

Increased activity of transcription factor NF-κB has been implicated in many B-cell lymphomas. We investigated effects of synthetic compound calafianin monomer (CM101) on biochemical and biological properties of NF-κB. In human 293 cells, CM101 selectively inhibited DNA binding by overexpressed NF-κB subunits REL (human c-Rel) and p65 as compared to NF-κB p50, and inhibition of REL and p65 DNA binding by CM101 required a conserved cysteine residue. CM101 also inhibited DNA binding by REL in human B-lymphoma cell lines, and the sensitivity of several B-lymphoma cell lines to CM101-induced proliferation arrest and apoptosis correlated with levels of cellular and nuclear REL. CM101 treatment induced both phosphorylation and decreased expression of anti-apoptotic protein Bcl-XL, a REL target gene product, in sensitive B-lymphoma cell lines. Ectopic expression of Bcl-XL protected SUDHL-2 B-lymphoma cells against CM101-induced apoptosis, and overexpression of a transforming mutant of REL decreased the sensitivity of BJAB B-lymphoma cells to CM101-induced apoptosis. Lipopolysaccharide-induced activation of NF-κB signaling upstream components occurred in RAW264.7 macrophages at CM101 concentrations that blocked NF-κB DNA binding. Direct inhibitors of REL may be useful for treating B-cell lymphomas in which REL is active, and may inhibit B-lymphoma cell growth at doses that do not affect some immune-related responses in normal cells.

May BDNF Be Implicated in the Exercise-Mediated Regulation of Inflammation? Critical Review and Synthesis of Evidence

Introduction:

Exercise attenuates inflammation and enhances levels of brain-derived neurotrophic factor (BDNF). Exercise also enhances parasympathetic tone, although its role in activating the cholinergic anti-inflammatory pathway is unclear. The physiological pathways of exercise’s effect on inflammation are obscure.

Aims:

To critically review the evidence on the role of BDNF in the anti-inflammatory effects of exercise and its potential involvement in the cholinergic anti-inflammatory pathway.

Methods:

Critical literature review of studies published in MEDLINE, PubMed, CINAHL, Embase, and Cochrane databases.

Results:

BDNF is critically involved in the bidirectional signaling between immune and neurosensory cells and in the regulation of parasympathetic system responses. BDNF is also intricately involved in the inflammatory response: inflammation induces BDNF production, and, in turn, BDNF exerts pro- and/or anti-inflammatory effects. Although exercise modulates BDNF and its receptors in lymphocytes, data on BDNF’s immunoregulatory/anti-inflammatory effects in relation to exercise are scarce. Moreover, BDNF increases cholinergic activity and is modulated by parasympathetic system activation. However, its involvement in the cholinergic anti-inflammatory pathway has not been investigated.

Conclusion:

Converging lines of evidence implicate BDNF in exercise-mediated regulation of inflammation; however, data are insufficient to draw concrete conclusions. We suggest that there is a need to investigate BDNF as a potential modulator/mediator of the anti-inflammatory effects of exercise and of the cholinergic anti-inflammatory pathway during exercise. Such research would have implications for a wide range of inflammatory diseases and for planning targeted exercise protocols.

Sorting receptor sortilin-a culprit in cardiovascular and neurological diseases

Sortilin is a sorting receptor that directs target proteins, such as growth factors, signaling receptors, and enzymes, to their destined location in secretory or endocytic compartments of cells. The activity of sortilin is essential for proper function of not only neurons but also non-neuronal cell types, and receptor (dys)function emerges as a major cause of malignancies, including hypercholesterolemia, retinal degeneration, neuronal cell loss in stroke and spinal cord injury, or Alzheimer's disease and other neurodegenerative disorders. In this article, we describe the molecular mechanisms of sortilin action in protein sorting and signaling and how modulation of receptor function may offer novel therapeutic strategies for treatment of common diseases of the cardiovascular and nervous systems.

Acute exercise modulates BDNF and pro-BDNF protein content in immune cells

PURPOSE

Although several studies have shown that immune cells stimulated by in vitro stress are capable to produce neurotrophins, there is still no evidence whether physiological stress, such as exercise, can modulate the in vivo levels of brain-derived neurotrophic factor (BDNF) in peripheral blood mononuclear cells (PBMCs).

METHODS

This work investigated whether acute exercise modulates the expression of BDNF, pro-BDNF, and p75(NTR) in the PBMCs of 10 healthy young men who performed a cycling incremental test to exhaustion (MAX) or exercised at individual anaerobic threshold (IAT). The PBMC expression of stress response proteins and the level of circulating BDNF, vascular endothelial growth growth factor, platelet-derived growth factor subunit B, basic fibroblast growth factor pro-inflammatory, and anti-inflammatory cytokines were analyzed as well.

RESULTS

A major finding is that both sessions of acute exercise regulated the content of BDNF isoforms within PBMCs in a manner related to the physiological stress exerted. Although the pro-BDNF increased after both MAX and IAT protocols, BDNF showed a kinetics dependent on exercise type: MAX induced a 54% protein increase immediately after exercise, followed by a significant drop 60 min after its conclusion (38% lower than the baseline). Differently, in the IAT, BDNF increased significantly up to 75% from the baseline throughout the recovery phase. All physiological parameters, as well as the p75(NTR) receptor and the stress-inducible proteins, were also differently regulated by the two exercise conditions.

CONCLUSIONS

These data supported the hypothesis that PBMCs might produce and secrete BDNF isoforms, as well as modulate the proteins p75(NTR) , Bcl-xL, hsp90, hsp27, and αB-crystallin, as part of the physiological stress response induced by acute exercise, offering a novel example of bidirectional interaction between nervous and immune systems.