Neurotrophin receptor p75(NTR) suppresses growth and nerve growth factor-mediated metastasis of human prostate cancer cells

Involvement of neuronal factors in tumor angiogenesis and the shaping of the cancer microenvironment

Emerging evidence suggests that nerves within the tumor microenvironment play a crucial role in regulating angiogenesis. Neurotransmitters and neuropeptides released by nerves can interact with nearby blood vessels and tumor cells, influencing their behavior and modulating the angiogenic response. Moreover, nerve-derived signals may activate signaling pathways that enhance the production of pro-angiogenic factors within the tumor microenvironment, further supporting blood vessel growth around tumors. The intricate network of communication between neural constituents and the vascular system accentuates the potential of therapeutically targeting neural-mediated pathways as an innovative strategy to modulate tumor angiogenesis and, consequently, neoplastic proliferation. Hereby, we review studies that evaluate the precise molecular interplay and the potential clinical ramifications of manipulating neural elements for the purpose of anti-angiogenic therapeutics within the scope of cancer treatment.

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.

The Journey of Cancer Cells to the Brain: Challenges and Opportunities

Cancer metastases into the brain constitute one of the most severe, but not uncommon, manifestations of cancer progression. Several factors control how cancer cells interact with the brain to establish metastasis. These factors include mediators of signaling pathways participating in migration, infiltration of the blood-brain barrier, interaction with host cells (e.g., neurons, astrocytes), and the immune system. Development of novel therapies offers a glimpse of hope for increasing the diminutive life expectancy currently forecasted for patients suffering from brain metastasis. However, applying these treatment strategies has not been sufficiently effective. Therefore, there is a need for a better understanding of the metastasis process to uncover novel therapeutic targets. In this review, we follow the journey of various cancer cells from their primary location through the diverse processes that they undergo to colonize the brain. These processes include EMT, intravasation, extravasation, and infiltration of the blood-brain barrier, ending up with colonization and angiogenesis. In each phase, we focus on the pathways engaging molecules that potentially could be drug target candidates.

Overexpression of p75NTR in Human Seminoma: A New Biomarker?

Several studies have demonstrated that the p75NTR low-affinity receptor of Nerve Growth Factor (NGF), is produced in abnormally large amounts in several human cancer types. However, the role of p75NTR varies substantially depending on cell context, so that a dual role of this receptor protein in tumor cell survival and invasion, as well as cell death, has been supported in recent studies. Herein we explored for the first time the expression of p75NTR in human specimens (nr = 40) from testicular germ cell tumors (TGCTs), mostly seminomas. Nuclear overexpression of p75NTR was detected by immunohistochemistry in seminoma tissue as compared to normal tissue, whereas neither NGF nor its high-affinity TrkA receptor was detected. An increased nuclear staining of phospho-JNK, belonging to the p75NTR signaling pathway and its pro-apoptotic target gene, p53, was concomitantly observed. Interestingly, our analysis revealed that decreased expression frequency of p75NTR, p-JNK and p53 was related to staging progression, thus suggesting that p75NTR may represent a specific marker for seminoma and staging in TGCTs.

Targeting the Nerve Growth Factor Signaling Impairs the Proliferative and Migratory Phenotype of Triple-Negative Breast Cancer Cells

Triple-negative breast cancer is a heterogeneous disease that still lacks specific therapeutic approaches. The identification of new biomarkers, predictive of the disease's aggressiveness and pharmacological response, is a challenge for a more tailored approach in the clinical management of patients. Nerve growth factor, initially identified as a key factor for neuronal survival and differentiation, turned out to be a multifaceted molecule with pleiotropic effects in quite divergent cell types, including cancer cells. Many solid tumors exhibit derangements of the nerve growth factor and its receptors, including the tropomyosin receptor kinase A. This receptor is expressed in triple-negative breast cancer, although its role in the pathogenesis and aggressiveness of this disease is still under investigation. We now report that triple-negative breast cancer-derived MDA-MB-231 and MDA-MB-453 cells express appreciable levels of tropomyosin receptor kinase A and release a biologically active nerve growth factor. Activation of tropomyosin receptor kinase by nerve growth factor treatment positively affects the migration, invasion, and proliferation of triple-negative breast cancer cells. An increase in the size of triple-negative breast cancer cell spheroids is also detected. This latter effect might occur through the nerve growth factor-induced release of matrix metalloproteinase 9, which contributes to the reorganization of the extracellular matrix and cell invasiveness. The tropomyosin receptor kinase A inhibitor GW441756 reverses all these responses. Co-immunoprecipitation experiments in both cell lines show that nerve growth factor triggers the assembly of the TrkA/β1-integrin/FAK/Src complex, thereby activating several downstream effectors. GW441756 prevents the complex assembly induced by nerve growth factor as well as the activation of its dependent signaling. Pharmacological inhibition of the tyrosine kinases Src and FAK (focal adhesion kinase), together with the silencing of β1-integrin, shows that the tyrosine kinases impinge on both proliferation and motility, while β1-integrin is needed for motility induced by nerve growth factor in triple-negative breast cancer cells. The present data support the key role of the nerve growth factor/tropomyosin receptor kinase A pathway in triple-negative breast cancer and offer new hints in the diagnostic and therapeutic management of patients.

NGFR Increases the Chemosensitivity of Colorectal Cancer Cells by Enhancing the Apoptotic and Autophagic Effects of 5-fluorouracil via the Activation of S100A9

Colorectal cancer (CRC) is currently the third leading cause of cancer-related deaths worldwide, and 5-fluorouracil (5-FU)-based chemotherapies serve as important adjuvant therapies before and after surgery for CRC. However, the efficacy of CRC chemotherapy is limited by chemoresistance, and therefore the discovery of novel markers to indicate chemosensitivity is essential. Nerve growth factor receptor (NGFR), a cell surface receptor, is involved in cell death and survival. Our previous study indicated that NGFR acts as a tumor suppressor, and high expression is associated with better outcomes in patients receiving 5-FU-based adjuvant chemotherapy after surgery. The aim of this study was to investigate the effect of NGFR on the chemotherapeutic response in CRC. Chemosensitivity was investigated using DLD1 and HCT8 cells after NGFR transfection. Apoptosis was investigated by flow cytometry. Autophagy was assessed using GFP-LC3B transient transfection. Gene expression was measured using an mRNA microarray. Beclin-1 and Bcl-2 protein expressions were assessed by western blot. NGFR and S100 calcium-binding protein A9 (S100A9) expressions in CRC patients were investigated by immunohistochemistry. The results showed that the half maximal inhibitory concentration of NGFR-transfected cells was lower than that of controls in DLD1 and HCT8 cells after 5-FU treatment, and cell viability was lower than in empty-vector cells. Tumor sizes were also smaller than in empty-vector cells in vivo. The percentages of apoptotic and autophagic cells were higher in NGFR-transfected cells. NGFR elevated the expression of S100A9 after 5-FU treatment. The combination of Bcl-2 and Beclin-1 was significantly suppressed by overexpressed NGFR. Five-year overall and disease-free survival in NGFR+/S100A9+ patients was better than in NGFR-/S100A9- patients. This study's findings suggest that NGFR may serve as a marker predicting CRC patients' chemosensitivity.

The p75NTR and its carboxyl-terminal fragment exert opposing effects on melanoma cell proliferation and apoptosis via modulation of the NF-κB pathway

The p75 neurotrophin receptor (p75NTR ), a member of the tumor necrosis factor superfamily of receptors, is sensitive to proteolysis and has been observed to be expressed in various cancers. However, the roles of p75NTR and its proteolytic fragments in tumorigenesis remain incompletely understood. Here, we report that the proportion of the p75NTR carboxyl-terminal fragment (p75NTR -CTF) is much higher than that of the full-length p75NTR (p75NTR -FL) in melanoma cells. Whereas p75NTR -FL positively regulates apoptosis, p75NTR -CTF promotes cell proliferation and survival, as well as increasing sorafenib resistance in vivo and in vitro. Moreover, p75NTR -CTF activates the nuclear factor kappa B pathway and enhances the mRNA and protein levels of its downstream genes c-IAP1/2, FLIP, bFGF, IL8 and VEGF. On the contrary, p75NTR -FL inhibits these processes. Taken together, these findings demonstrate that p75NTR -CTF and p75NTR -FL have opposing functions in melanoma cells, suggesting that the ratio of the two proteins affects the balance between cell death and survival. The presence of distinct p75NTR proteolytic fragments may affect biological outcomes in tumor cells.

Immunoexpression of BDNF, TrkB, and p75NTR receptors in peripheral neural lesions of the head and neck

BACKGROUND

Brain-derived neurotrophic factor (BDNF) and neurotrophin receptors have been recognized as fundamental regulators of normal brain development, homeostasis, and plasticity. They have also been studied in the behavior of central nervous system tumors. Here, we studied the pattern of BDNF, TrkB and p75NTR immunoexpression in peripheral benign and malignant neural lesions in head and neck.

METHODS

This cross-sectional analytical study included 79 cases of head and neck neural lesions. Nineteen cases of traumatic neuromas (TN), 20 cases of granular cell tumors (GCT), 16 cases of neurofibromas (NF), 20 cases of schwannomas (SC), and 4 malignant peripheral nerve sheath tumor (MPNST) were submitted to immunohistochemistry with BDNF, TrkB, and p75NTR antibodies. A semi-quantitative analysis was performed.

RESULTS

The analysis of BDNF demonstrated a high percentage of positive cells in TN, GCT and SC with a decrease in cases of NF and MPNST. TrkB presented a lower significant immunoexpression in GCT in relation to the TN, NF, SC, and MPNST (P < .0001); and TN showed less percentage of positive cell compared to SC (P = .0017). Regarding p75NTR, the percentage of positive cell was significantly reduced in MPNST compared GCT (P = .009), NF (P = .0138) and SC (P = .0069). Also, a decrease in TN compared to GCT (P = .007) was observed.

CONCLUSIONS

Our results showed the immunoreactivity of BDNF, TrkB, and p75NTR in head and neck peripheral neural lesions. Reduction of BDNF and p75NTR in MPNST might suggest down-regulation during the acquisition of malignant phenotype.

The neurotrophic tyrosine kinase receptor 1 (TrkA) is overexpressed in oesophageal squamous cell carcinoma

Nerve growth factor (NGF) and its receptors, the neurotrophic receptor tyrosine kinase 1 (NTRK1/TrkA) and the common neurotrophin receptor (NGFR/p75^NTR), are increasingly implicated in cancer progression, but their clinicopathological significance in oesophageal cancer is unclear. In this study, the expression of NGF, NTRK1 and NGFR were analysed by immunohistochemistry in a cohort of 303 oesophageal cancers versus 137 normal adjacent oesophageal tissues. Immunostaining was digitally quantified and compared to clinicopathological parameters. NGF and NGFR staining were found in epithelial cells and at similar levels between oesophageal cancers and normal oesophageal tissue. NGFR staining was slightly increased with grade (p=0.0389). Interestingly, NTRK1 staining was markedly higher in oesophageal squamous cell carcinoma (OR 2.31, 95%CI 1.13-4.38, p<0.0001) and significantly lower in adenocarcinoma (OR 0.50, 95%CI 0.44-0.63, p<0.0001) compared to normal oesophageal tissue. In addition, NTRK1 staining was decreased in grade 2 and grade 3 (OR 0.51, 95%CI 0.21-1.40, p<0.0001) compared to grade 1, suggesting a preferential involvement of this receptor in the more differentiated forms of oesophageal carcinomas. Together, these data point to NTRK1 as a biomarker and a candidate therapeutic target in oesophageal squamous cell carcinoma.

Decoding the Role of CD271 in Melanoma

The evolution of melanoma, the most aggressive type of skin cancer, is triggered by driver mutations that are acquired in the coding regions of particularly BRAF (rat fibrosarcoma serine/threonine kinase, isoform B) or NRAS (neuroblastoma-type ras sarcoma virus) in melanocytes. Although driver mutations strongly determine tumor progression, additional factors are likely required and prerequisite for melanoma formation. Melanocytes are formed during vertebrate development in a well-controlled differentiation process of multipotent neural crest stem cells (NCSCs). However, mechanisms determining the properties of melanocytes and melanoma cells are still not well understood. The nerve growth factor receptor CD271 is likewise expressed in melanocytes, melanoma cells and NCSCs and programs the maintenance of a stem-like and migratory phenotype via a comprehensive network of associated genes. Moreover, CD271 regulates phenotype switching, a process that enables the rapid and reversible conversion of proliferative into invasive or non-stem-like states into stem-like states by yet largely unknown mechanisms. Here, we summarize current findings about CD271-associated mechanisms in melanoma cells and illustrate the role of CD271 for melanoma cell migration and metastasis, phenotype-switching, resistance to therapeutic interventions, and the maintenance of an NCSC-like state.

The p75 neurotrophin receptor is required for the survival of neuronal progenitors and normal formation of the basal forebrain, striatum, thalamus and neocortex

During development, the p75 neurotrophin receptor (p75^NTR) is widely expressed in the nervous system where it regulates neuronal differentiation, migration and axonal outgrowth. p75^NTR also mediates the survival and death of newly born neurons, with functional outcomes being dependent on both timing and cellular context. Here, we show that knockout of p75^NTR from embryonic day 10 (E10) in neural progenitors using a conditional Nestin-Cre p75^NTR floxed mouse causes increased apoptosis of progenitor cells. By E14.5, the number of Tbr2-positive progenitor cells was significantly reduced and the rate of neurogenesis was halved. Furthermore, in adult knockout mice, there were fewer cortical pyramidal neurons, interneurons, cholinergic basal forebrain neurons and striatal neurons, corresponding to a relative reduction in volume of these structures. Thalamic midline fusion during early postnatal development was also impaired in Nestin-Cre p75^NTR floxed mice, indicating a novel role for p75^NTR in the formation of this structure. The phenotype of this strain demonstrates that p75^NTR regulates multiple aspects of brain development, including cortical progenitor cell survival, and that expression during early neurogenesis is required for appropriate formation of telencephalic structures.

Nerve Growth Factor Induces Proliferation and Aggressiveness In Prostate Cancer Cells

Resistance to hormone therapy and disease progression is the major challenge in clinical management of prostate cancer (PC). Drugs currently used in PC therapy initially show a potent antitumor effects, but PC gradually develops resistance, relapses and spreads. Most patients who fail primary therapy and have recurrences eventually develop castration-resistant prostate cancer (CRPC), which is almost incurable. The nerve growth factor (NGF) acts on a variety of non-neuronal cells by activating the NGF tyrosine-kinase receptor, tropomyosin receptor kinase A (TrkA). NGF signaling is deregulated in PC. In androgen-dependent PC cells, TrkA mediates the proliferative action of NGF through its crosstalk with the androgen receptor (AR). Epithelial PC cells, however, acquire the ability to express NGF and TrkA, as the disease progresses, indicating a role for NGF/TrkA axis in PC progression and androgen-resistance. We here report that once activated by NGF, TrkA mediates proliferation, invasiveness and epithelial-mesenchymal transition (EMT) in various CRPC cells. NGF promotes organoid growth in 3D models of CRPC cells, and specific inhibition of TrkA impairs all these responses. Thus TrkA represents a new biomarker to target in CRPC.

Death domain of p75 neurotrophin receptor: a structural perspective on an intracellular signalling hub

The death domain (DD) is a globular protein motif with a signature feature of an all-helical Greek-key motif. It is a primary mediator of a variety of biological activities, including apoptosis, cell survival and cytoskeletal changes, which are related to many neurodegenerative diseases, neurotrauma, and cancers. DDs exist in a wide range of signalling proteins including p75 neurotrophin receptor (p75^NTR ), a member of the tumour necrosis factor receptor superfamily. The specific signalling mediated by p75^NTR in a given cell depends on the type of ligand engaging the extracellular domain and the recruitment of cytosolic interactors to the intracellular domain, especially the DD, of the receptor. In solution, the p75^NTR -DDs mainly form a symmetric non-covalent homodimer. In response to extracellular signals, conformational changes in the p75^NTR extracellular domain (ECD) propagate to the p75^NTR -DD through the disulfide-bonded transmembrane domain (TMD) and destabilize the p75^NTR -DD homodimer, leading to protomer separation and exposure of binding sites on the DD surface. In this review, we focus on recent advances in the study of the structural mechanism of p75^NTR -DD signalling through recruitment of diverse intracellular interactors for the regulation and control of diverse functional outputs.

The neurotrophic tyrosine kinase receptor TrkA and its ligand NGF are increased in squamous cell carcinomas of the lung

The neurotrophic tyrosine kinase receptor TrkA (NTRK1) and its ligand nerve growth factor (NGF) are emerging promoters of tumor progression. In lung cancer, drugs targeting TrkA are in clinical trials, but the clinicopathological significance of TrkA and NGF, as well as that of the precursor proNGF, the neurotrophin co-receptor p75^NTR and the proneurotrophin co-receptor sortilin, remains unclear. In the present study, analysis of these proteins was conducted by immunohistochemistry and digital quantification in a series of 204 lung cancers of different histological subtypes versus 121 normal lung tissues. TrkA immunoreactivity was increased in squamous cell carcinoma compared with benign and other malignant lung cancer histological subtypes (p < 0.0001). NGF and proNGF were also increased in squamous cell carcinoma, as well as in adenocarcinoma (p < 0.0001). In contrast, p75^NTR was increased across all lung cancer histological subtypes compared to normal lung (p < 0.0001). Sortilin was higher in adenocarcinoma and small cell carcinoma (p < 0.0001). Nerves in the tumor microenvironment were negative for TrkA, NGF, proNGF, p75^NTR and sortilin. In conclusion, these data suggest a preferential therapeutic value of targeting the NGF-TrkA axis in squamous cell carcinomas of the lung.

Nerve growth factor modulates the tumor cells migration in ovarian cancer through the WNT/β-catenin pathway

Nerve growth factor (NGF)/nerve growth factor receptors (NGFRs) axis and canonical WNT/β-catenin pathway have shown to play crucial roles in tumor initiation, progression and prognosis. But little did we know the relationship between them in modulation of tumor progress. In this report, we found that NGF/NGFRs and β-catenin were coexpression in ovarian cancer cell lines, and NGF can decrease the expression level of β-catenin and affect its activities, which may be related to the NGF-induced down-regulation of B-cell CLL/lymphoma 9-like (BCL9L, BCL9-2). Furthermore, NGF can also increase or decrease the downstream target gene expression levels of WNT/β-catenin depending on the cell types. Especially, we created a novel in vitro cell growth model based on a microfluidic device to intuitively observe the effects of NGF/NGFRs on the motility behaviors of ovarian cancer cells. The results showed that the migration area and maximum distance into three dimensional (3D) matrigel were decreased in CAOV3 and OVCAR3 cells, but increased in SKOV3 cells following the stimulation with NGF. In addition, we found that the cell colony area was down-regulated in CAOV3 cells, however, it was augmented in OVCAR3 cells after treatment with NGF. The inhibitors of NGF/NGFRs, such as Ro 08-2750, K252a and LM11A-31,can all block NGF-stimulated changes of gene expression or migratory behavior on ovarian cancer cells. The different results among ovarian cancer cells illustrated the heterogeneity and complexity of ovarian cancer. Collectively, our results suggested for the first time that NGF is functionally linked to β-catenin in the migration of human ovarian cancer cells, which may be a novel therapeutic perspective to prevent the spread of ovarian carcinomas by studying the interaction between NGF/NGFRs and canonical WNT/β-catenin signaling.

Trophic and neurotrophic factors in human pituitary adenomas (Review)

The pituitary gland is an organ that functionally connects the hypothalamus with the peripheral organs. The pituitary gland is an important regulator of body homeostasis during development, stress, and other processes. Pituitary adenomas are a group of tumors arising from the pituitary gland: they may be subdivided in functional or non-functional, depending on their hormonal activity. Some trophic and neurotrophic factors seem to play a key role in the development and maintenance of the pituitary function and in the regulation of hypothalamo-pituitary-adrenocortical axis activity. Several lines of evidence suggest that trophic and neurotrophic factors may be involved in pituitary function, thus suggesting a possible role of the trophic and neurotrophic factors in the normal development of pituitary gland and in the progression of pituitary adenomas. Additional studies might be necessary to better explain the biological role of these molecules in the development and progression of this type of tumor. In this review, in light of the available literature, data on the following neurotrophic factors are discussed: ciliary neurotrophic factor (CNTF), transforming growth factors β (TGF‑β), glial cell line-derived neurotrophic factor (GDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), vascular endothelial growth inhibitor (VEGI), fibroblast growth factors (FGFs) and epidermal growth factor (EGF) which influence the proliferation and growth of pituitary adenomas.

Generation and characterization of a human oral squamous carcinoma cell line SCC-9 with CRISPR/Cas9-mediated deletion of the p75 neurotrophin receptor

OBJECTIVE

To investigate the importance of the p75 neurotrophin receptor (p75^NTR) in human tongue squamous carcinoma cells, we exploited the CRISPR/Cas9 technology to establish a p75^NTR-knockout SCC-9 cell line and to explore the effect on biological functions.

MATERIALS AND METHODS

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated endonuclease (Cas9) system was used to generate genomic deletion mutants of p75^NTR in the tongue squamous carcinoma cell lines SCC-9. Single-guide RNA (sgRNA) sequences were designed to target the p75^NTR genomic sequence and were cloned into plasmid pGK1.1. The linearized vector was electroporated into SCC-9 cells and p75^NTR deletion was confirmed using Cruiser™ enzyme digestion and PCR amplification. SCC-9 clones with successful deletion of p75^NTR were identified and verified by sequencing and selected for functional testing in cell proliferation, invasion, migration, and colony-forming assays.

RESULTS

Compared with control cells, p75^NTR-knockout SCC-9 cells showed significantly diminished abilities to proliferate, invade, migrate, and form colonies, indicating a reduction in pro-tumorigenic behavior.

CONCLUSION

These data demonstrate, first, that the CRISPR/Cas9 system is a simplified method for generating p75^NTR knockouts with relatively high efficiency, and second, that deletion of p75^NTR suppresses several tumor-promoting properties of SCC-9 cells, suggesting that p75^NTR is a potential target for the development of novel therapies for tongue cancer.

p75 neurotrophin receptor: A potential surface marker of tongue squamous cell carcinoma stem cells

The present study detected p75 neurotrophin receptor (p75^NTR) expression in tongue squamous cell carcinoma (TSCC) cell lines, in order to define the biological properties of p75^NTR+ cells and to confirm the use of p75^NTR+ as a surface marker for TSCC stem cells. p75^NTR+ cells were separated from Tca-8113 and CAL-27 TSCC cells by fluorescence-activated cell sorting. Colony formation, MTT and scratch assays, and a tumorigenicity analysis were performed to measure self-renewal and proliferation, multidirectional differentiation, and tumorigenicity of p75^NTR+ cells. p75^NTR+ cells comprised 3.1 and 1.9% of Tca-8113 and CAL-27 cells (mean of three experiments), respectively, and were more able to form colonies compared with non-sorted cells (P<0.01). In addition, the proportion of p75^NTR+ cells generated from monoclonal p75^NTR+ cells decreased to 14.5 (Tca-8113) and 5.8% (CAL-27) of cells within 2 weeks, thus suggesting that p75^NTR+ cells are able to generate p75^NTR+ and p75^NTR− cells. Furthermore, p75^NTR+ cells exhibited increased proliferation, as evidenced by MTT assay (P<0.01) and had greater metastatic ability according to the scratch assay (P<0.01), compared with non-sorted cells. p75^NTR+ cells also exhibited a greater tumorigenic capacity compared with non-sorted cells. In conclusion, p75^NTR+ cells isolated from TSCC cell lines possess the characteristics of cancer stem cells; therefore, p75^NTR may be considered a useful surface marker for the identification of TSCC stem cells.

Canine Central Nervous System Neoplasm Phenotyping Using Tissue Microarray Technique

Tissue microarrays (TMAs) represent a useful technique for the simultaneous phenotyping of large sample numbers and are particularly suitable for histopathologic tumor research. In this study, TMAs were used to evaluate semiquantitatively the expression of multiple antigens in various canine central nervous system (CNS) neoplasms and to identify markers with potential discriminative diagnostic relevance. Ninety-seven canine CNS neoplasms, previously diagnosed on hematoxylin and eosin sections according to the World Health Organization classification, were investigated on TMAs, with each tumor consisting of 2 cylindrical samples from the center and the periphery of the neoplasm. Tumor cells were phenotyped using a panel of 28 monoclonal and polyclonal antibodies, and hierarchical clustering analysis was applied to group neoplasms according to similarities in their expression profiles. Hierarchical clustering generally grouped cases with similar histologic diagnoses; however, gliomas especially exhibited a considerable heterogeneity in their positivity scores. Multiple tumor groups, such as astrocytomas and oligodendrogliomas, significantly differed in the proportion of positive immunoreaction for certain markers such as p75NTR, AQP4, GFAP, and S100 protein. The study highlights AQP4 and p75NTR as novel markers, helping to discriminate between canine astrocytoma and oligodendroglioma. Furthermore, the results suggest that p75NTR and proteolipid protein may represent useful markers, whose expression inversely correlates with malignant transformation in canine astrocytomas and oligodendrogliomas, respectively. Tissue microarray was demonstrated to be a useful and time-saving tool for the simultaneous immunohistochemical characterization of multiple canine CNS neoplasms. The present study provides a detailed overview of the expression patterns of different types of canine CNS neoplasms.

Extranuclear partners of androgen receptor: at the crossroads of proliferation, migration, and neuritogenesis

In this review, we focus on the role played by the protein partners of ligand-activated extranuclear androgen receptor (AR) in the final effects of hormone action, such as proliferation, migration, and neuritogenesis. The choice of AR partner, at least in part, depends on cell type. Androgen-activated receptor directly associates with cytoplasmic Src tyrosine kinase in epithelial cells, whereas in mesenchymal and neuronal cells, it prevalently interacts with filamin A. In the former, proliferation represents the final hormonal outcome, whereas in the latter, either migration or neuritogenesis, respectively, occurs. Furthermore, AR partner filamin A is replaced with Src when mesenchymal cells are stimulated with very low androgen concentrations. Consequently, the migratory effect is replaced by mitogenesis. Use of peptides that prevent receptor/partner assembly abolishes the effects that are dependent on their association and offers new therapeutic approaches to AR-related diseases. Perturbation of migration is often associated with metastatic spreading in cancer. In turn, cell cycle aberration causes tumors to grow faster, whereas toxic signaling triggers neurodegenerative events in the CNS. Here, we provide examples of new tools that interfere in rapid androgen effects, including migration, proliferation, and neuronal differentiation, together with their potential therapeutic applications in AR-dependent diseases-mainly prostate cancer and neurodegenerative disorders.-Castoria, G., Auricchio, F., Migliaccio, A. Extranuclear partners of androgen receptor: at the crossroads of proliferation, migration, and neuritogenesis.

CD271 regulates the proliferation and motility of hypopharyngeal cancer cells

CD271 (p75 neurotrophin receptor) plays both positive and negative roles in cancer development, depending on the cell type. We previously reported that CD271 is a marker for tumor initiation and is correlated with a poor prognosis in human hypopharyngeal cancer (HPC). To clarify the role of CD271 in HPC, we established HPC cell lines and knocked down the CD271 expression using siRNA. We found that CD271-knockdown completely suppressed the cells’ tumor-forming capability both in vivo and in vitro. CD271-knockdown also induced cell-cycle arrest in G₀ and suppressed ERK phosphorylation. While treatment with an ERK inhibitor only partially inhibited cell growth, CDKN1C, which is required for maintenance of quiescence, was strongly upregulated in CD271-depleted HPC cells, and the double knockdown of CD271 and CDKN1C partially rescued the cells from G₀ arrest. In addition, either CD271 depletion or the inhibition of CD271-RhoA signaling by TAT-Pep5 diminished the in vitro migration capability of the HPC cells. Collectively, CD271 initiates tumor formation by increasing the cell proliferation capacity through CDKN1C suppression and ERK-signaling activation, and by accelerating the migration signaling pathway in HPC.

Nerve growth factor receptor negates the tumor suppressor p53 as a feedback regulator

Cancer develops and progresses often by inactivating p53. Here, we unveil nerve growth factor receptor (NGFR, p75NTR or CD271) as a novel p53 inactivator. p53 activates NGFR transcription, whereas NGFR inactivates p53 by promoting its MDM2-mediated ubiquitin-dependent proteolysis and by directly binding to its central DNA binding domain and preventing its DNA-binding activity. Inversely, NGFR ablation activates p53, consequently inducing apoptosis, attenuating survival, and reducing clonogenic capability of cancer cells, as well as sensitizing human cancer cells to chemotherapeutic agents that induce p53 and suppressing mouse xenograft tumor growth. NGFR is highly expressed in human glioblastomas, and its gene is often amplified in breast cancers with wild type p53. Altogether, our results demonstrate that cancers hijack NGFR as an oncogenic inhibitor of p53.

DOI:http://dx.doi.org/10.7554/eLife.15099.001

Cancer often develops as a result of alterations to “tumor suppressor” genes within cells. This results in the cells growing and dividing too much, which causes a tumor to form. One of the most important tumor suppressor genes produces a protein called p53, which is lost or mutated in roughly half of all human cancers. In the other half of cancers p53 itself is normal, but is often disabled by proteins that promote tumor growth.

One of the remaining challenges in the field of cancer research is to identify which proteins inhibit p53 directly. Identifying these proteins would help clarify why many human cancers, such as some brain cancers, breast and skin cancers, often maintain a normal form of the p53 tumor suppressor protein.

Zhou et al. now provide evidence that shows that a protein called nerve growth factor receptor (NGFR) is one such protein. NGFR was known to be important for the healthy development of the brain and nervous system. Unexpectedly, however, Zhou et al. found that NGFR binds directly to p53 and disables it in several types of human cancer cells. This finding is likely to be important because NGFR is produced in abnormally high amounts in several human cancer types, including skin, breast, bone and some brain cancers.

Reducing the levels of NGFR in cancer cells caused the cells to become more sensitive to some anti-cancer drugs. Overall, the results presented by Zhou et al. suggest that developing new drugs that target NGFR could produce new treatments for human cancers that have a normal form of the gene that produces p53. More experiments are also needed to find out whether NGFR has other ways of promoting the development of cancerous tumors.

DOI:http://dx.doi.org/10.7554/eLife.15099.002

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.

Gamma-secretase-independent role for cadherin-11 in neurotrophin receptor p75 (p75(NTR)) mediated glioblastoma cell migration

The p75 neurotrophin receptor (p75(NTR)) undergoes γ-secretase-mediated regulated intramembrane proteolysis and is involved in glioblastoma cell migration and invasion. Consistent with previous reports, in this study we show that p75NTR increases U87-MG glioblastoma cell migration, which is reversed by inhibition of γ-secretase activity. However, we show that expression or stabilization of the γ-secretase-generated p75(NTR) intracellular domain (ICD) is not sufficient to induce U87-MG glioblastoma cell migration, and that exogenous expression of p75(NTR) ICD inhibits p75(NTR)-mediated glioblastoma cell (U87-MG and U373-MG) migration. To identify pathways and to determine how p75(NTR) mediates glioblastoma migration we utilized a microarray approach to assess differential gene expression profiles between parental U87-MG and cells stably expressing wild-type p75(NTR), a γ-secretase cleavage-resistant chimeric p75(NTR) mutant (p75FasTM) and the γ-secretase-generated p75(NTR)-ICD, which mimics constitutively cleaved p75(NTR) receptor. In our microarray data analysis we identified a subset of genes that were constitutively up-regulated in wild-type p75(NTR) cells, which were also repressed in p75(NTR) ICD expressing cells. Furthermore, our data revealed among the many differentially expressed genes, cadherin-11 (Cdh-11), matrix metalloproteinase 12 and relaxin/insulin-like family peptide receptor 2 as constitutively up-regulated in wild-type p75(NTR) cells, independent of γ-secretase activity. Consistent with a role in glioblastoma migration, we found that U87-p75(NTR) cells express higher levels of Cdh-11 protein and that siRNA-mediated knockdown of Cdh-11 resulted in a significant decrease in p75(NTR)-mediated glioblastoma cell migration. Therefore, we hypothesize that p75(NTR) can impact U87-MG glioblastoma cell migration in a γ-secretase-independent manner through modulation of specific genes, including Cdh-11, and that both γ-secretase-independent and -dependent mechanisms are involved in p75(NTR)-mediated U87-MG glioblastoma cell migration.

Differential regulation of macrophage phenotype by mature and pro-nerve growth factor

To characterize the role of neurotrophin receptors on macrophages, we investigated the ability of nerve growth factor (NGF) and its precursor, proNGF, to regulate human macrophage phenotype. The p75 neurotrophin receptor (p75(NTR)) and TrkA were concentrated within overlapping domains on membrane ruffles. NGF stimulation of macrophages increased membrane ruffling, calcium spiking, phagocytosis and growth factor secretion. In contrast, proNGF induced podosome formation, increased migration, suppressed calcium spikes and increased neurotoxin secretion. These results demonstrate opposing roles of NGF and proNGF in macrophage regulation providing new avenues for pharmacological intervention during neuroinflammation.

P75 nerve growth factor receptors modulate development of GnRH neurons and olfactory ensheating cells

Temporal and spatial localization of nerve growth factor receptor (p75NGFR) in the developing olfactory system and gonadotropin-releasing hormone-1 (GnRH) system was characterized and its role analyzed using p75NGFR null mice and nasal explants. Prenatally, p75NGFR was expressed by GnRH neurons and olfactory ensheathing cells (OECs). In p75NGFR null mice, no change in the number of GnRH cells was detected as compared to wild-type. However, in null mice, a shift in the distribution of GnRH neurons was found, with a small population of GnRH cells migrating further caudally toward the median eminence. Additionally, a reduction of both GAD67 positive olfactory axons and GFAP positive OEC fibers occurred. Acute administration of a p75NGFR blocker to GnRH cells maintained in vitro increased migration rate, consistent with the change in distribution detected in p75NGFR null mice. Chronic inhibition of p75NGFR caused an attenuation of olfactory axon fasciculation and a decrease in OEC density, again mimicking the changes detected in null mice. However, a reduction in GnRH cell number was found after chronic treatment that not observed in KO animals suggesting indirect changes occur during chronic treatment in vitro and/or a compensatory mechanism occurs in vivo that prevents loss of GnRH neurons in the absence of p75NGFR.

Identification of novel microRNA regulatory pathways associated with heterogeneous prostate cancer

BACKGROUND

MicroRNAs (miRNAs) are potential regulators that contribute to the pathogenesis of cancer. Microarray technologies have been widely used to characterize aberrant miRNA expression patterns in cancer. Nevertheless, the miRNAs expression signatures identified for a same cancer differs among laboratories due to the cancer heterogeneity. In addition, how the deregulated miRNAs coordinately contribute to the tumourigenic process of prostate cancer remains elusive.

RESULTS

We evaluated five outlier detection algorithms that take into account the heterogeneity of cancer samples. ORT was selected as the best method and applied to four prostate cancer associated microRNA expression datasets. After microRNA target prediction and pathway enrichment mapping, 38 Gene Ontology terms, 16 KEGG pathways and 99 GeneGO pathways are found putative prostate cancer associated. Comparison with our previous studies, we identified two putative novel pathways important in prostate cancer. The two novel pathways are 1) ligand-independent activation of ESR1 and ESR2 and 2) membrane-bound ESR1: interaction with growth factors signalling.

CONCLUSIONS

We proved that expression signatures of at the pathway level well address the cancer heterogeneity and are more consistent than at the miRNA/gene levels. Based on this observation, we identified putative novel microRNA regulatory pathways which will help us to elucidate the cooperative function of different microRNAs in prostate cancer.

Nerve growth factor induces cell cycle arrest of astrocytes

Neurotrophins can influence multiple cellular functions depending on the cellular context and the specific receptors they interact with. These neurotrophic factors have been extensively studied for their ability to support neuronal survival via Trk receptors and to induce apoptosis via the p75(NTR). However, the p75(NTR) is also detected on cell populations that do not undergo apoptosis in response to neurotrophins. In particular, the authors have detected p75(NTR) expression on astrocytes during development and after seizure-induced injury. In this study, the authors investigated the role of Nerve growth factor (NGF) in regulating astrocyte proliferation and in influencing specific aspects of the cell cycle. The authors have demonstrated that NGF prevents the induction of cyclins and their association with specific cyclin-dependent kinases, and thereby prevents progression through the G1 phase of the cell cycle. Since the authors have previously shown that p75(NTR) but not TrkA, is expressed in astrocytes, these data suggest that activation of p75(NTR) promotes withdrawal of astrocytes from the cell cycle, which may have important consequences during development and after injury.

Nerve growth factor in cancer cell death and survival

One of the major challenges for cancer therapeutics is the resistance of many tumor cells to induction of cell death due to pro-survival signaling in the cancer cells. Here we review the growing literature which shows that neurotrophins contribute to pro-survival signaling in many different types of cancer. In particular, nerve growth factor, the archetypal neurotrophin, has been shown to play a role in tumorigenesis over the past decade. Nerve growth factor mediates its effects through its two cognate receptors, TrkA, a receptor tyrosine kinase and p75NTR, a member of the death receptor superfamily. Depending on the tumor origin, pro-survival signaling can be mediated by TrkA receptors or by p75NTR. For example, in breast cancer the aberrant expression of nerve growth factor stimulates proliferative signaling through TrkA and pro-survival signaling through p75NTR. This latter signaling through p75NTR promotes increased resistance to the induction of cell death by chemotherapeutic treatments. In contrast, in prostate cells the p75NTR mediates cell death and prevents metastasis. In prostate cancer, expression of this receptor is lost, which contributes to tumor progression by allowing cells to survive, proliferate and metastasize. This review focuses on our current knowledge of neurotrophin signaling in cancer, with a particular emphasis on nerve growth factor regulation of cell death and survival in cancer.

Natural antibodies against nerve growth factor inhibit in vitro prostate cancer cell metastasis

Prostate cancer is a major cause of death in older men, and bone metastasis is the primary cause of morbidity and mortality in prostate cancer. Prostate is an abundant source of nerve growth factor (NGF) that is secreted by malignant epithelial cells and utilized as an important autocrine factor for growth and metastasis. We previously showed that intravenous gammaglobulin (IVIg) contains natural antibodies against NGF, which inhibit growth and differentiation of the NGF-dependent cell line PC-12. In the present study, we examined the effects of these natural antibodies on in vitro migration or metastasis of two prostate cancer cell lines namely DU-145 and PC-3. Cancer cell migration was assessed using these cell lines in the upper chambers of Matrigel invasion chambers. The effects of IVIg and affinity-purified anti-NGF antibodies on cell migration through membrane into the lower chamber were assessed in dose/response experiments by a colorimetric method. Affinity-purified natural IgG anti-NGF antibody inhibited DU-145 migration by 38% (p = 0.01) and PC-3 migration by 25% (p = 0.02); whereas, a monoclonal anti-NGF antibody inhibited DU-145 migration by 40% (p = 0.01) and PC-3 migration by 37% (p = 0.02), at the same concentration. When IVIg was depleted of NGF-specific IgG by affinity chromatography, there was no significant inhibition of migration of the DU-145 and PC-3 cells at a concentration of 1 mg/well. Removal of the NGF-specific antibody from the IVIg was also demonstrated by a lack of effect on PC-12 cell differentiation. Therefore, IVIg is able to inhibit the migration of prostate cancer cell lines, through Matrigel chambers in vitro, only when the natural NGF-specific antibodies actively are present in IVIg.

Establishment of a novel human esophageal squamous cell carcinoma cell line (ESC-410) and its partial biological characterization

Esophageal cancer exhibits an uneven geographical distribution strikingly, resulting in focal endemic high-incidence areas in several countries worldwide including China, which might be associated with the environmental and genetic risk factors in those areas. Permanent cancer cell lines are invaluable tools in understanding the biology of cancers and experimental therapeutics. To enrich cell line panel and animal models of human esophageal squamous cell carcinoma (ESCC) from different geographical areas and investigate the environmental and genetic risk factors in the carcinogenesis of ESCC, a novel human esophageal squamous cancer cell line (ESC-410) was established. The cell line grew adherent as a monolayer and maintained stable growth rate with a doubling time of 53 h and distinct epithelial morphological appearance; it was maintained in vitro for 18 months and subcultured for more than 50 passages. Ultrastructural examination revealed large irregular nuclei, desmosome, and tonofilaments; karyotype analysis showed a modal number of chromosomes that ranged from 35 to 73, with a median of 57, and 77% of analyzed cells were hyperdiploidy; reverse transcription polymerase chain reaction (RT-PCR) detected the mRNA expressions of CK8, CK18, and CK19 in the established cells; immunofluorescence assay identified the protein expressions of neurotrophin receptor p75 and integrin α6 (CD49f) in the ESC-410 cell line; xenotransplantation of ESC-410 cells into athymic nude mice subcutaneously induced the formation of solid tumor masses in about 2 weeks. By histopathological examination, heterogeneity of xenograft tumor was observed, as same as that of human primary ESCC. All findings and evidence in this experimental study suggested that this cell line might be a useful model in vitro and in vivo in cellular and molecular studies as well as in testing novel therapies for human ESCC.

CASZ1, a candidate tumor-suppressor gene, suppresses neuroblastoma tumor growth through reprogramming gene expression

Neuroblastoma (NB) is a common childhood malignant tumor of the neural crest-derived sympathetic nervous system. In NB the frequent loss of heterozygosity (LOH) on chromosome 1p raises the possibility that this region contains tumor-suppressor genes whose inactivation contributes to tumorigenesis. The human homolog of the Drosophila neural fate determination gene CASZ1, a zinc-finger transcription factor, maps to chromosome 1p36.22, a region implicated in NB tumorigenesis. Quantitative real-time PCR analysis showed that low-CASZ1 expression is significantly correlated with increased age (≥18 months), Children's Oncology Group high-risk classification, 1p LOH and MYCN amplification (all P<0.0002) and decreased survival probability (P=0.0009). CASZ1 was more highly expressed in NB with a differentiated histopathology (P<0.0001). Retinoids and epigenetic modification agents associated with regulation of differentiation induced CASZ1 expression. Expression profiling analysis revealed that CASZ1 regulates the expression of genes involved in regulation of cell growth and developmental processes. Specific restoration of CASZ1 in NB cells induced cell differentiation, enhanced cell adhesion, inhibited migration and suppressed tumorigenicity. These data are consistent with CASZ1 being a critical modulator of neural cell development, and that somatically acquired disruption of normal CASZ1 expression contributes to the malignant phenotype of human NB.

NSAID inhibition of prostate cancer cell migration is mediated by Nag-1 Induction via the p38 MAPK-p75(NTR) pathway

The nonsteroidal anti-inflammatory drugs (NSAID) R-flurbiprofen and ibuprofen have been shown to induce expression of p75(NTR) (neurotrophin receptor) in prostate cancer cell lines. p75(NTR), a tumor necrosis factor receptor superfamily member, is a proapoptotic protein that functions as a tumor suppressor in the human prostate. Expression of p75(NTR) is lost as prostate cancer progresses and is minimal in several metastatic prostate cancer cell lines. NSAIDs induce p75(NTR) through activation of the p38 mitogen-activated protein kinase (MAPK) pathway, with a concomitant decrease in cell survival. Here, we show that treatment with R-flurbiprofen and ibuprofen induces expression of the NSAID-activated gene-1 (Nag-1) protein, a divergent member of the TGF beta (TGF-β) family, in PC-3 cells. Using the selective pharmacologic inhibitor of p38 MAPK, SB202190, and p38 MAPK-specific siRNA (small interfering RNA), we show that Nag-1 induction following NSAID treatment is mediated by the p38 MAPK pathway. p75(NTR)-specific siRNA pretreatment shows that Nag-1 induction by NSAIDs is downstream of p75(NTR) induction. Decreased survival of NSAID-treated cells is rescued by p75(NTR)-specific siRNA but not by Nag-1 siRNA. Transwell chamber and in vitro wound healing assays demonstrate decreased cell migration upon NSAID treatment. Pretreatment of PC-3 cells with p75(NTR) and Nag-1-specific siRNA shows that NSAID inhibition of cell migration is mediated by Nag-1 and p75(NTR). These results demonstrate a role for Nag-1 in NSAID inhibition of cell migration, but not survival.

Antitumor progression potential of caffeic acid phenethyl ester involving p75(NTR) in C6 glioma cells

The previous data showed that caffeic acid phenethyl ester (CAPE), a component of propolis, possesses inducing cell cycle arrest and antiproliferation effect on C6 glioma cells in vitro and in vivo. In the present study, C6 glioma cells treated with CAPE resulted in morphological changes to an astrocytic phenotype and increased the expression of glial differentiation marker proteins including glial fibrillary acidic protein (GFAP) and S-100β. In addition, with scratch assay and Boyden chamber assay, CAPE exhibited inhibitory effects on the motility and invasion of C6 glioma cells. Furthermore, CAPE induced the expression of nerve growth factor (NGF) and p75 neurotrophin receptor (p75(NTR)), which were involved in neural cell differentiation. CAPE could also inhibit the activity of matrix metalloproteinases (MMPs) and induce the expression of RhoB, a tumor suppressor. To examine the involvement of p75(NTR) in the anti-invasive property of CAPE, Western blotting and Boyden Chamber assay were performed by addition of an anti-p75(NTR) antibody in C6 cells. The results showed that blocking p75(NTR) could decrease the CAPE-induced expression of RhoB and the inactivation of MMP-2, -9 as well as the anti-invasion effect in C6 glioma cells. Furthermore, CAPE suppressed IκB-α phosphorylation which was down stream of p75(NTR). Finally, the effect of CAPE on metastasis by lung colonization of the tumor cell in nude mice was also evaluated. It was found that the groups of nude mice injected with CAPE-pretreated cells could decrease both lung size and weight as compared to the positive control group which did not receive CAPE treatment. In addition, histological examination of the mouse lung sections showed that the CAPE-treated group inhibited the metastasis of C6 glioma cells. These data suggest CAPE possesses antitumor progression potential.

Nerve growth factor signaling in prostate health and disease

The prostate is one of the most abundant sources of nerve growth factor (NGF) in different species, including humans. NGF and its receptors are implicated in the control of prostate cell proliferation and apoptosis and it can either support or suppress cell growth. The co-expression of both NGF receptors, p75(NGFR) and tropomyosin-related kinase A (trkA), represents a crucial condition for the antiproliferative effect of NGF; indeed, p75(NGFR) is progressively lost during prostate tumorigenesis and its disappearance represents a malignancy marker of prostate adenocarcinoma (PCa). Interestingly, a dysregulation of NGF signal transduction was found in a number of human tumors. This review summarizes the current knowledge on the role of NGF and its receptors in prostate and in PCa. Conclusions bring to the hypothesis that the NGF network could be a candidate for future pharmacological manipulation in the PCa therapy: in particular the re-expression of p75(NTR) and/or the negative modulation of trkA could represent a target to induce apoptosis and to reduce proliferation and invasiveness of PCa.

Novel localization of low affinity NGF receptor (p75) in the stroma of prostate cancer and possible implication in neoplastic invasion: an immunohistochemical and ultracytochemical study

BACKGROUND

The localization of low affinity nerve growth factor receptor (p75) in prostate carcinogenesis is still unclear. Our aim was to reinvestigate the localization of p75 in normal and pathological prostate and to check a possible correlation to neoplastic grading.

METHODS

Specimens from 33 prostate cancers and from normal prostatic tissue were analyzed for p75 expression at light and ultrastructural levels.

RESULTS

In normal tissue p75-immunoreactivity was restricted to basal cells in the epithelial compartment and to nerves and blood vessel in stroma. During carcinogenesis, p75-immunoreactivity progressively decreased at the periphery of the foci according to the increase in malignancy. No p75-immunoreactivity was detected inside of the foci. On the contrary, in stroma we found a dramatic increase in p75-immunoreactivity correlated to an increase in malignancy. In this compartment, for the first time ultrastructural analysis identified p75-immunoreactivity in smooth muscle cells (SMC) that are p75-negative in normal conditions.

CONCLUSION

The present study confirms at ultrastructural level a malignant-dependent p75 decrease in basal cells of neoplastic foci. Furthermore, we show a novel, malignant-dependent localization of p75 in SMC in the stroma around the neoplastic foci. Since p75 expression is present in muscle cells only during the earliest stages of differentiation and mature muscle cells lose this expression, we hypothesize that p75 re-expression in stromal SMC is a further mechanism related to the general de-differentiation of the stroma connected to the neoplastic invasion. According to this hypothesis, our results suggest that p75 analysis could be a novel prognostic marker for prostate cancer.

Her2 crosstalks with TrkA in a subset of prostate cancer cells: rationale for a guided dual treatment

BACKGROUND

To date, no effective therapeutic treatment prevents prostate cancer (PCa) progression to more advanced and invasive disease forms. It has been demonstrated that the simultaneous high expression of p185(HER2) and TrkA might confer a proliferative advantage to PCa cells.

METHODS

In this work we verified the crosstalk between TrkA and Her2 signaling pathways and the effects of a combined treatment with Her2 and TrkA inhibitors.

RESULTS

NGF induced TrkA activation and stimulated cell proliferation of PCa cells. NGF induced also tyrosine phosphorylation of p185(HER2). This event was only partially inhibited by the pan Trk inhibitor, CEP-701 but was strongly blocked by pertuzumab, a humanized antibody blocking Her2 heterodimerization. In presence of NGF, TrkA and Her2 co-precipitated and this was dependent to the relative high cellular levels of TrkA since when cell lysates were immunoprecipitated with an antibody against Her2 the amount of TrkA were proportional to the cellular levels of this receptor. On the contrary when we immunoprecipitated using an antibody against TrkA the amount of Her2 seemed independent to cellular levels of Her2. So, combined treatment between CEP-701 and pertuzumab showed supra-additive effects in cells with higher levels of TrkA and Her2 suggesting once again that this was indicative of a higher response to treatment.

CONCLUSIONS

Our data suggest that the dual inhibition of TrkA and Her2 may be useful in a subset of patients in which TrkA and Her2 are overexpressed and in which the possibility of TrkA and Her2 protein-binding is elevated.

Carprofen induction of p75NTR-dependent apoptosis via the p38 mitogen-activated protein kinase pathway in prostate cancer cells

The p75 neurotrophin receptor (p75(NTR)) functions as a tumor suppressor in prostate epithelial cells, where its expression declines with progression to malignant cancer. Previously, we showed that treatment with R-flurbiprofen or ibuprofen induced p75(NTR) expression in several prostate cancer cell lines leading to p75(NTR)-mediated decreased survival. Using the 2-phenyl propionic acid moiety of these profens as a pharmacophore, we screened an in silico database of 30 million compounds and identified carprofen as having an order of magnitude greater activity for induction of p75(NTR) levels and inhibition of cell survival. Prostate (PC-3 and DU-145) and bladder (T24) cancer cells were more sensitive to carprofen induction of p75(NTR)-associated loss of survival than breast (MCF-7) and fibroblast (3T3) cells. Transfection of prostate cell lines with a dominant-negative form of p75(NTR) before carprofen treatment partially rescued cell survival, showing a cause-and-effect relationship between carprofen induction of p75(NTR) levels and inhibition of survival. Carprofen induced apoptotic nuclear fragmentation in prostate but not in MCF-7 and 3T3 cells. Furthermore, small interfering RNA knockdown of the p38 mitogen-activated protein kinase (MAPK) protein prevented induction of p75(NTR) by carprofen in both prostate cell lines. Carprofen treatment induced phosphorylation of p38 MAPK as early as within 1 min. Expression of a dominant-negative form of MK2, the kinase downstream of p38 MAPK frequently associated with signaling cascades leading to apoptosis, prevented carprofen induction of the p75(NTR) protein. Collectively, we identify carprofen as a highly potent profen capable of inducing p75(NTR)-dependent apoptosis via the p38 MAPK pathway in prostate cancer cells.

Nerve growth factor receptor (p75 NTR) and pattern of invasion predict poor prognosis in oral squamous cell carcinoma

AIMS

To evaluate the expression of p75 neurotrophin receptor (p75(NTR)) in oral squamous cell carcinoma (OSCC). The results were related to tumour node metastasis (TNM) stage, World Health Organization (WHO) grade, invasive front grading (IFG) and prognosis.

METHODS AND RESULTS

Immunohistochemically, the expression of p75(NTR) was assessed in 53 T1-T2 OSCCs. Clinical data were recorded prospectively. The end-point was disease-free survival. All tumours expressed p75(NTR), and this expression, both in central/superficial tumour areas and at the invasive front, was associated with poor prognosis (P = 0.03 and P = 0.02) (log rank test). Tumours with marked cellular dissociation (IFG parameter) had more recurrences than tumours with collective tumour cell invasion (P = 0.03). In tumours showing both p75(NTR) at the invasive front and marked tumour cell dissociation, the average risk of recurrence was increased about 17 times (Cox regression analysis) compared with tumours with low p75(NTR) expression and collective invasion. Traditional prognostic systems were of no prognostic significance.

CONCLUSION

p75(NTR) was expressed in all OSCCs. p75(NTR) expression and the pattern of invasion were significantly associated with a poor prognosis in OSCCs, and both were better prognostic factors than traditional prognostic parameters. The combination of p75(NTR) expression and the pattern of invasion strongly increased precision in the identification of tumours with poor disease-free survival.

Gene-modified bone marrow cell therapy for prostate cancer

There is a critical need to develop new and effective cancer therapies that target bone, the primary metastatic site for prostate cancer and other malignancies. Among the various therapeutic approaches being considered for this application, gene-modified cell-based therapies may have specific advantages. Gene-modified cell therapy uses gene transfer and cell-based technologies in a complementary fashion to chaperone appropriate gene expression cassettes to active sites of tumor growth. In this paper, we briefly review potential cell vehicles for this approach and discuss relevant gene therapy strategies for prostate cancer. We further discuss selected studies that led to the conceptual development and preclinical testing of IL-12 gene-modified bone marrow cell therapy for prostate cancer. Finally, we discuss future directions in the development of gene-modified cell therapy for metastatic prostate cancer, including the need to identify and test novel therapeutic genes such as GLIPR1.

High nerve growth factor receptor (p75NTR) expression is a favourable prognostic factor in paediatric B cell precursor-acute lymphoblastic leukaemia

Nerve growth factor (NGF) plays a pivotal role in cellular survival/death decisions with the low affinity receptor p75NTR predominately transmitting anti-proliferative signals. In spite of its established role in B-cell function and identification as a prognostically favourable marker in a number of malignancies, little is known about the expression pattern and prognostic significance of p75NTR in B cell precursor-acute lymphoblastic leukaemia (BCP-ALL). p75NTR expression was prospectively studied on primary ALL-blasts in a cohort of paediatric patients with common ALL (n = 86) and preB-ALL (n = 34) treated within the Co-operative study group for childhood acute lymphoblastic leukaemia (CoALL) protocol, CoALL06-97. Flow cytometric analysis showed that almost half of the patients expressed no or negligible amounts of p75NTR (<10%). The median expression in patients expressing p75NTR beyond that threshold was 49% (range 11-100%). In patients classified as low-risk at diagnosis, p75NTR expression was significantly higher than in high-risk patients (P = 0.001). Of note, p75NTR expression was lower in the 21 patients who subsequently developed relapse compared with those remaining in remission (P = 0.038). Accordingly, relapse-free survival was significantly better in patients expressing high surface p75NTR (P = 0.041). Thus, in this prospective analysis, high p75NTR expression was a strong prognostic marker that identified a group of paediatric ALL patients with favourable outcome.

The p38 MAPK pathway mediates aryl propionic acid induced messenger rna stability of p75 NTR in prostate cancer cells

The p75(NTR) acts as a tumor suppressor in the prostate, but its expression is lost as prostate cancer progresses and is minimal in established prostate cancer cell lines such as PC-3, DU-145, and LNCaP. Previously, we showed that treatment with R-flurbiprofen or ibuprofen induced p75(NTR) expression in PC-3 and DU-145 cells leading to p75(NTR)-mediated decreased survival. Here, we investigate the mechanism by which these drugs induce p75(NTR) expression. We show that the observed increase in p75(NTR) protein due to R-flurbiprofen and ibuprofen treatment was accompanied by an increase in p75(NTR) mRNA, and this increase in mRNA was the result of increased mRNA stability and not by an up-regulation of transcription. In addition, we show that treatment with R-flurbiprofen or ibuprofen led to sustained activation of the p38 mitogen-activated protein kinase (MAPK) pathway. Furthermore, inhibition of the p38 MAPK pathway with the p38 MAPK-specific inhibitor SB202190 or by small interfering RNA (siRNA) knockdown of p38 MAPK protein prevented induction of p75(NTR) by R-flurbiprofen and ibuprofen. We also observed that siRNA knockdown of MAPK-activated protein kinase (MK)-2 and MK3, the kinases downstream of p38 MAPK that are responsible for the mRNA stabilizing effects of the p38 MAPK pathway, also prevented an induction of p75(NTR) by R-flurbiprofen and ibuprofen. Finally, we identify the RNA stabilizing protein HuR and the posttranscriptional regulator eukaryotic translation initiation factor 4E as two possible mechanisms by which the p38 MAPK pathway may increase p75(NTR) expression. Collectively, the data suggest that R-flurbiprofen and ibuprofen induce p75(NTR) expression by increased mRNA stability that is mediated through the p38 MAPK pathway.

The biological role of the low-affinity p75 neurotrophin receptor in esophageal squamous cell carcinoma

In this study, we investigated the clinicopathologic significance of the low-affinity p75 neurotrophin receptor (p75NTR; which is expressed in the stem/progenitor cell fraction of normal esophageal epithelial cells) in 187 resected esophageal squamous cell carcinoma (ESCC) specimens and found that approximately 50% of ESCC expressed p75NTR. Our investigation using ESCC cell lines showed that p75NTR was intensely expressed in the cells with high colony-forming capacity but they were sensitive to cell death on inhibition of p75NTR expression with transient transfection of small interfering RNA (siRNA). These findings suggest that p75NTR is necessary for survival and maintenance of ESCC tumors, providing us with a potential target for novel therapies.

PURPOSE

p75NTR is expressed in a stem/progenitor cell fraction of human normal esophageal epithelial cells. In this study, we investigated the expression and biological role of p75NTR in ESCC.

EXPERIMENTAL DESIGN

The expression of p75NTR in 187 resected ESCC specimens was immunohistochemically investigated. The expression of p75NTR in 30 ESCC cell lines (KYSEs) was assessed by reverse transcription-PCR, immunocytochemistry, and flow cytometry. The p75NTR-bright and p75NTR-dim/negative cells were isolated from KYSE150 by magnetic beads and colony formation was investigated. The role of p75NTR in KYSEs was assessed by transient transfection of siRNA.

RESULTS

p75NTR was expressed in 92 of 187 (49.2%) tumors. In well-differentiated tumors, positive staining was apparent in the first one to two layers from infiltrative margin of the tumors where most of the cells were actively proliferating. In moderately differentiated tumors, p75NTR was expressed in wider range from the margin of the tumors whereas p75NTR was diffusely distributed in poorly differentiated tumors. p75NTR was expressed in all examined KYSEs and the mean proportion of the p75NTR-bright fraction was 30.1%. The size of p75NTR-positive colonies was larger than that of p75NTR-negative colonies derived from KYSE150 (P<0.0001). The purified p75NTR-bright cells formed p75NTR-positive large colonies more frequently than the p75NTR-dim/negative cells (P<0.0001). Down-regulation of p75NTR expression by siRNA resulted in marked growth inhibition with induction of apoptosis.

CONCLUSIONS

Our findings suggest that p75NTR is necessary for survival and maintenance of ESCC tumors, providing us with a potential target for novel therapies.

In vitro and in vivo effects of bicalutamide on the expression of TrkA and P75 neurotrophin receptors in prostate carcinoma

RATIONALE

Neurotrophine tyrosine kinase receptors (NTR) are expressed in prostate carcinoma (PCa), and their distribution seems to be related to disease malignancy.

MATERIAL AND METHODS

In this article we analyzed the expression of NTRK1 (TrkA), NTRK2 (TrkB), NTRK3 (TrkC), and p75NTR in a 102 patient cohort with clinically localized tumors, which had been surgically treated with radical prostatectomy (RP). Among these, 61 patients received RP as sole treatment, and 41 patients received neoadjuvant hormone therapy (NHT) for 120 days with bicalutamide 150 mg/day. In addition, we analyzed the NTR expression in vitro in the androgen receptor positive, androgen-sensitive cell strains derived from CWR22R.

RESULTS AND CONCLUSIONS

We demonstrated that: (i) TrkA and TrkC levels were significantly upmodulated, whereas (ii) p75NTR seemed to be reduced, and (iii) TrkB expression seemed to be not affected by NHT. TrkA were constitutively activated when its levels were very high. In vitro studies showed that the dehydrotestosterone (DHT) was able to maintain low TrkA and TrkC protein levels. Conversely, DHT was able to maintain p75NTR at high levels. Bicalutamide treatment induced TrkA and TrkC and reduced p75NTR expression. Antiproliferative effects of CEP701 were dependent to TrkA levels. A therapeutical effect of CEP701 was seen in all culture conditions, and bicalutamide seemed to sensitize prostate cancer cells to the effects of a pan TrkA inhibitor CEP701, suggesting that a sequential therapy between these drugs could further increase the efficacy of Trk inhibition.

The aryl propionic acid R-flurbiprofen selectively induces p75NTR-dependent decreased survival of prostate tumor cells

Epidemiologic studies show that patients chronically consuming nonsteroidal anti-inflammatory drugs (NSAID) for arthritis exhibit a reduced incidence of prostate cancer. In addition, some NSAIDs show anticancer activity in vitro. NSAIDs exert their anti-inflammatory effects by inhibiting cyclooxygenase (COX) activity; however, evidence suggests that COX-independent mechanisms mediate decreased prostate cancer cell survival. Hence, we examined the effect of selected aryl propionic acid NSAIDs and structurally related compounds on the decreased survival of prostate cancer cell lines PC-3, DU-145, and LNCaP by induction of the p75(NTR) protein. p75(NTR) has been shown to function as a tumor suppressor in the prostate by virtue of its intracellular death domain that can initiate apoptosis and inhibit growth. The most efficacious compounds for induction of p75(NTR) and decreased survival, in rank-order, were R-flurbiprofen, ibuprofen, oxaprozin, fenoprofen, naproxen, and ketoprofen. Because R-flurbiprofen and ibuprofen exhibited the greatest efficacy, we examined their dose-dependent specificity of induction for p75(NTR) relative to other members of the death receptor family. Whereas treatment with R-flurbiprofen or ibuprofen resulted in a massive induction of p75(NTR) protein levels, the expression of Fas, p55(TNFR), DR3, DR4, DR5, and DR6 remained largely unchanged. Moreover, transfection of either cell line before R-flurbiprofen or ibuprofen treatment with a dominant negative form of p75(NTR) to antagonize p75(NTR) activity or p75(NTR) small interfering RNA to prevent p75(NTR) protein expression rescued both cell lines from decreased survival. Hence, R-flurbiprofen and ibuprofen selectively induce p75(NTR)-dependent decreased survival of prostate cancer cells independently of COX inhibition.