Neuropilin-2 regulates α6β1 integrin in the formation of focal adhesions and signaling

Role of Semaphorins, neuropilins and plexins in cancer progression

Progress in understanding nervous system-cancer interconnections has emphasized the functional role of semaphorins (SEMAs) and their receptors, neuropilins (NRPs) and plexins (PLXNs), in cancer progression. SEMAs are a conserved and extensive family of broadly expressed soluble and membrane-associated proteins that were first described as regulators of axon guidance and neural and vascular development. However, recent advances have shown that they can have a dual role in cancer progression, acting either as tumor promoters or suppressors. SEMAs effects result from their interaction with specific co-receptors/receptors NRPs/PLXNs, that have also been described to play a role in cancer progression. They can influence both cancer cells and tumor microenvironment components modulating various aspects of tumorigenesis such as oncogenesis, tumor growth, invasion and metastatic spread or treatment resistance. In this review we focus on the role of these axon guidance signals and their receptors and co/receptors in various aspects of cancer. Furthermore, we also highlight their potential application as novel approaches for cancer treatment in the future.

Integrin β1 in breast cancer: mechanisms of progression and therapy

The therapy for breast cancer (BC), to date, still needs improvement. Apart from traditional therapy methods, biological therapy being explored opens up a novel avenue for BC patients. Integrin β1 (ITGβ1), one of the largest subgroups in integrin family, is a key player in cancer evolution and therapy. Recent researches progress in the relationship of ITGβ1 level and BC, finding that ITGβ1 expression evidently concerns BC progression. In this chapter, we outline diverse ITGβ1-based mechanisms regarding to the promoted effect of ITGβ1 on BC cell structure rearrangement and malignant phenotype behaviors, the unfavorable patient prognosis conferred by ITGβ1, BC therapy tolerance induced by ITGβ1, and lastly novel inhibitors targeting ITGβ1 for BC therapy. As an effective biomarker, ITGβ1 undoubtedly emerges one of targeted-therapy opportunities of BC patients in future. It is a necessity focusing on scientific and large-scale clinical trials on the validation of targeted-ITGβ1 drugs for BC patients.

Biomechanical properties of laminins and their impact on cancer progression

Laminins (LMs) constitute a family of heterotrimeric glycoproteins essential for the formation of basement membranes (BM). They act as molecular bridges between cells and the extracellular matrix (ECM), thereby transmitting signals influencing cell behavior and tissue organization. In the realm of cancer pathobiology, LMs regulate key processes such as migration, differentiation, or fibrosis. This review critically examines the multifaceted impact of LMs on tumor progression, with a particular focus on the isoform-specific structure-function relationships, and how this structural diversity contributes to the biomechanical properties of BMs. LM interactions with integrin and non-integrin cell surface receptors, as well as with other ECM proteins, modify the response of cancer cells to the ECM stiffness, ultimately influencing the capacity of malignant cells to breach the BM, a limiting step in metastatic dissemination. Comprehension of the mechanisms underlying LM-driven tumor biomechanics holds potential for better understand cancer pathobiology and design new targeted therapeutic strategies.

Insight into the mechanism of CD34+ cell mobilisation impairment in multiple myeloma patients treated with anti-CD38 therapy

Induction therapy followed by CD34+ cell mobilisation and autologous transplantation represents standard of care for multiple myeloma (MM). However, the anti-CD38 monoclonal antibodies daratumumab and isatuximab have been associated with mobilisation impairment, yet the mechanism remains unclear. In this study, we investigated the effect of three different regimens (dara-VCd, isa-KRd and VTd) on CD34+ cells using flow cytometry and transcriptomics. Decreased CD34+ cell peak concentration and yields, longer collection and delayed engraftment were reproduced after dara-VCd/isa-KRd versus VTd induction in 34 patients in total. Using flow cytometry, we detected major changes in the proportion of apheresis product and bone marrow CD34+ subsets in patients treated with regimens containing anti-CD38 therapy; however, without any decrease in CD38high B-lymphoid progenitors in both materials. RNA-seq of mobilised CD34+ cells from 21 patients showed that adhesion genes are overexpressed in CD34+ cells after dara-VCd/isa-KRd and JCAD, NRP2, MDK, ITGA3 and CLEC3B were identified as potential target genes. Finally, direct in vitro effect of isatuximab in upregulating JCAD and CLEC3B was confirmed by quantitative PCR. These findings suggest that upregulated adhesion-related interactions, rather than killing of CD34+ cells by effector mechanisms, could be leading causes of decreased mobilisation efficacy in MM patients treated with anti-CD38 therapy.

Orchestrating Resilience: How Neuropilin-2 and Macrophages Contribute to Cardiothoracic Disease

Immunity has evolved to balance the destructive nature of inflammation with wound healing to overcome trauma, infection, environmental insults, and rogue malignant cells. The inflammatory response is marked by overlapping phases of initiation, resolution, and post-resolution remodeling. However, the disruption of these events can lead to prolonged tissue damage and organ dysfunction, resulting long-term disease states. Macrophages are the archetypic phagocytes present within all tissues and are important contributors to these processes. Pleiotropic and highly plastic in their responses, macrophages support tissue homeostasis, repair, and regeneration, all while balancing immunologic self-tolerance with the clearance of noxious stimuli, pathogens, and malignant threats. Neuropilin-2 (Nrp2), a promiscuous co-receptor for growth factors, semaphorins, and integrins, has increasingly been recognized for its unique role in tissue homeostasis and immune regulation. Notably, recent studies have begun to elucidate the role of Nrp2 in both non-hematopoietic cells and macrophages with cardiothoracic disease. Herein, we describe the unique role of Nrp2 in diseases of the heart and lung, with an emphasis on Nrp2 in macrophages, and explore the potential to target Nrp2 as a therapeutic intervention.

Genetic Loss of miR-205 Causes Increased Mammary Gland Development

MiRNAs play crucial roles in a broad spectrum of biological processes, both physiological and pathological. Different reports implicate miR-205 in the control of breast stem cell properties. Differential miR-205 expression has been observed in different stages of mammary gland development and maturation. However, a functional role in this process has not been clearly demonstrated. We generated an miR-205 knockout in the FVB/N mouse strain, which is viable and characterized by enhanced mammary gland development. Indeed, mammary glands of miR-205-/- female mice at different ages (1.5 and 5.5 months) show increased outgrowth and branching. This evidence is consistent with our previously reported data demonstrating the direct miR-205-mediated targeting of HER3, a master regulator of mammary gland development, and the oncosuppressive activity of this microRNA in different types of breast cancer.

Recent progress on the effect of extracellular matrix on occurrence and progression of breast cancer

Breast cancer (BC) metastasis is an enormous challenge targeting BC therapy. The extracellular matrix (ECM), the principal component of the BC metastasis niche, is the pivotal driver of breast tumor development, whose biochemical and biophysical characteristics have attracted widespread attention. Here, we review the biological effects of ECM constituents and the influence of ECM stiffness on BC metastasis and drug resistance. We provide an overview of the relative signal transduction mechanisms, existing metastasis models, and targeted drug strategies centered around ECM stiffness. It will shed light on exploring more underlying targets and developing specific drugs aimed at ECM utilizing biomimetic platforms, which are promising for breast cancer treatment.

Profiling and targeting cancer stem cell signaling pathways for cancer therapeutics

Tumorigenic cancer stem cells (CSCs) represent a subpopulation of cells within the tumor that express genetic and phenotypic profiles and signaling pathways distinct from the other tumor cells. CSCs have eluded many conventional anti-oncogenic treatments, resulting in metastases and relapses of cancers. Effectively targeting CSCs' unique self-renewal and differentiation properties would be a breakthrough in cancer therapy. A better characterization of the CSCs' unique signaling mechanisms will improve our understanding of the pathology and treatment of cancer. In this paper, we will discuss CSC origin, followed by an in-depth review of CSC-associated signaling pathways. Particular emphasis is given on CSC signaling pathways' ligand-receptor engagement, upstream and downstream mechanisms, and associated genes, and molecules. Signaling pathways associated with regulation of CSC development stand as potential targets of CSC therapy, which include Wnt, TGFβ (transforming growth factor-β)/SMAD, Notch, JAK-STAT (Janus kinase-signal transducers and activators of transcription), Hedgehog (Hh), and vascular endothelial growth factor (VEGF). Lastly, we will also discuss milestone discoveries in CSC-based therapies, including pre-clinical and clinical studies featuring novel CSC signaling pathway cancer therapeutics. This review aims at generating innovative views on CSCs toward a better understanding of cancer pathology and treatment.

Inhibition of VEGF binding to neuropilin-2 enhances chemosensitivity and inhibits metastasis in triple-negative breast cancer

Although blocking the binding of vascular endothelial growth factor (VEGF) to neuropilin-2 (NRP2) on tumor cells is a potential strategy to treat aggressive carcinomas, a lack of effective reagents that can be used clinically has hampered this potential therapy. Here, we describe the generation of a fully humanized, high-affinity monoclonal antibody (aNRP2-10) that specifically inhibits the binding of VEGF to NRP2, conferring antitumor activity without causing toxicity. Using triple-negative breast cancer as a model, we demonstrated that aNRP2-10 could be used to isolate cancer stem cells (CSCs) from heterogeneous tumor populations and inhibit CSC function and epithelial-to-mesenchymal transition. aNRP2-10 sensitized cell lines, organoids, and xenografts to chemotherapy and inhibited metastasis by promoting the differentiation of CSCs to a state that is more responsive to chemotherapy and less prone to metastasis. These data provide justification for the initiation of clinical trials designed to improve the response of patients with aggressive tumors to chemotherapy using this monoclonal antibody.

Targeting integrin pathways: mechanisms and advances in therapy

Integrins are considered the main cell-adhesion transmembrane receptors that play multifaceted roles as extracellular matrix (ECM)-cytoskeletal linkers and transducers in biochemical and mechanical signals between cells and their environment in a wide range of states in health and diseases. Integrin functions are dependable on a delicate balance between active and inactive status via multiple mechanisms, including protein-protein interactions, conformational changes, and trafficking. Due to their exposure on the cell surface and sensitivity to the molecular blockade, integrins have been investigated as pharmacological targets for nearly 40 years, but given the complexity of integrins and sometimes opposite characteristics, targeting integrin therapeutics has been a challenge. To date, only seven drugs targeting integrins have been successfully marketed, including abciximab, eptifibatide, tirofiban, natalizumab, vedolizumab, lifitegrast, and carotegrast. Currently, there are approximately 90 kinds of integrin-based therapeutic drugs or imaging agents in clinical studies, including small molecules, antibodies, synthetic mimic peptides, antibody-drug conjugates (ADCs), chimeric antigen receptor (CAR) T-cell therapy, imaging agents, etc. A serious lesson from past integrin drug discovery and research efforts is that successes rely on both a deep understanding of integrin-regulatory mechanisms and unmet clinical needs. Herein, we provide a systematic and complete review of all integrin family members and integrin-mediated downstream signal transduction to highlight ongoing efforts to develop new therapies/diagnoses from bench to clinic. In addition, we further discuss the trend of drug development, how to improve the success rate of clinical trials targeting integrin therapies, and the key points for clinical research, basic research, and translational research.

LINC01798/miR-17-5p axis regulates ITGA8 and causes changes in tumor microenvironment and stemness in lung adenocarcinoma

Integrins are closely related to the occurrence and development of tumors. ITGA8 encodes the alpha 8 subunit of the heterodimeric integrin alpha8beta1. Studies on the role of this gene in the occurrence and development of lung cancer are scarce. The examination of public databases revealed that ITGA8 expression was significantly lower in tumor tissue than that in normal tissue, especially in lung cancer, renal carcinoma, and prostate cancer. Survival analysis of patients with lung adenocarcinoma revealed that higher ITGA8 expression had better prognosis. ITGA8 was positively related to immune checkpoints and immunomodulators, whereas B cell, CD4+ T cell, CD8+ T cell, neutrophil, macrophage, and dendritic cell infiltration had the same correlation. Moreover, ITGA8 was negatively related to cancer stemness. We used an online database to predict the miRNAs and lncRNAs that regulate ITGA8 and obtained the regulatory network of ITGA8 through correlation analysis and Kaplan-Meier survival analysis. Quantitative real-time PCR and western blot analyses showed that LINC01798 regulates ITGA8 expression through miR-17-5p. Therefore, the regulatory network of ITGA8 may serve as a new therapeutic target to improve the prognosis of patients with lung cancer.

Role of Neuropilin-2-mediated signaling axis in cancer progression and therapy resistance

Neuropilins (NRPs) are transmembrane proteins involved in vascular and nervous system development by regulating angiogenesis and axon guidance cues. Several published reports have established their role in tumorigenesis. NRPs are detectable in tumor cells of several cancer types and participate in cancer progression. NRP2 is also expressed in endothelial and immune cells in the tumor microenvironment and promotes functions such as lymphangiogenesis and immune suppression important for cancer progression. In this review, we have taken a comprehensive approach to discussing various aspects of NRP2-signaling in cancer, including its regulation, functional significance in cancer progression, and how we could utilize our current knowledge to advance the studies and target NRP2 to develop effective cancer therapies.

Endothelial neuropilin-2 influences angiogenesis by regulating actin pattern development and α5-integrin-p-FAK complex recruitment to assembling adhesion sites

The ability to form a variety of cell-matrix connections is crucial for angiogenesis to take place. Without stable anchorage to the extracellular matrix (ECM), endothelial cells (ECs) are unable to sense, integrate and disseminate growth factor stimulated responses that drive growth of a vascular bed. Neuropilin-2 (NRP2) is a widely expressed membrane-bound multifunctional non-tyrosine kinase receptor, which has previously been implicated in influencing cell adhesion and migration by interacting with α5-integrin and regulating adhesion turnover. α5-integrin, and its ECM ligand fibronectin (FN) are both known to be upregulated during the formation of neo-vasculature. Despite being descriptively annotated as a candidate biomarker for aggressive cancer phenotypes, the EC-specific roles for NRP2 during developmental and pathological angiogenesis remain unexplored. The data reported here support a model whereby NRP2 actively promotes EC adhesion and migration by regulating dynamic cytoskeletal remodeling and by stimulating Rab11-dependent recycling of α5-integrin-p-FAK complexes to newly assembling adhesion sites. Furthermore, temporal depletion of EC-NRP2 in vivo impairs primary tumor growth by disrupting vessel formation. We also demonstrate that EC-NRP2 is required for normal postnatal retinal vascular development, specifically by regulating cell-matrix adhesion. Upon loss of endothelial NRP2, vascular outgrowth from the optic nerve during superficial plexus formation is disrupted, likely due to reduced FAK phosphorylation within sprouting tip cells.

N2E4, a Monoclonal Antibody Targeting Neuropilin-2, Inhibits Tumor Growth and Metastasis in Pancreatic Ductal Adenocarcinoma via Suppressing FAK/Erk/HIF-1α Signaling

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with extremely limited treatment; the effective targeting strategy stays an urgent unmet need. Neuropilin-2 (NRP2), a multifunctional transmembrane non-tyrosine-kinase glycoprotein, enhances various signal transduction pathways to modulate cancer progression. However, the application value of NRP2 as a therapeutic target in pancreatic cancer is still unclear. Here, we detected the elevated NRP2 was associated with the poor prognosis of pancreas carcinoma. The mouse monoclonal antibody targeting NRP2 (N2E4) that could specifically bind to PDAC cells was developed. Moreover, N2E4 inhibits PDAC proliferation, migration, and invasion in vitro, and repressed growth and metastasis in vivo. Mechanistically, the effect of N2E4 was mainly related to the blocking of interaction between NRP2 with integrinβ1 to inhibit FAK/Erk/HIF-1a/VEGF signaling. Therefore, N2E4 has the potential for targeting therapy of PDAC. This study lays a foundation for the future development of NRP2-based targeted therapy for PDAC.

DCBLD1 is associated with the integrin signaling pathway and has prognostic value in non-small cell lung and invasive breast carcinoma

Germline single nucleotide polymorphisms in the promoter region of the DCBLD1 gene are associated with non-smoking cases of both non-small cell lung carcinoma (NSCLC) and human papillomavirus-negative head and neck cancer. However the clinical relevance and function of DCBLD1 remain unclear. This multicenter retrospective study was designed to evaluate the prognostic value and function of DCBLD1 in the four main solid cancers: NSCLC, invasive breast carcinoma, colorectal adenocarcinoma and prostate adenocarcinoma. We included the following cohorts: GSE81089 NSCLC, METABRIC invasive breast carcinoma, GSE14333 colorectal adenocarcinoma, GSE70770 prostate adenocarcinoma and The Cancer Genome Atlas (TCGA) Firehose Legacy cohorts of all four cancers. DCBLD1 gene expression was associated with a worse overall survival in multivariate analyses for both NSCLC cohorts (TCGA: P = 0.03 and GSE81089: P = 0.04) and both invasive breast carcinoma cohorts (TCGA: P = 0.02 and METABRIC: P < 0.001). Patients with high DCBLD1 expression showed an upregulation of the integrin signaling pathway in comparison to those with low DCBLD1 expression in the TCGA NSCLC cohort (FDR = 5.16 × 10^-14) and TCGA invasive breast carcinoma cohort (FDR = 1.94 × 10^-05).

Focal adhesion dynamics in cellular function and disease

Acting as a bridge between the cytoskeleton of the cell and the extra cellular matrix (ECM), the cell-ECM adhesions with integrins at their core, play a major role in cell signalling to direct mechanotransduction, cell migration, cell cycle progression, proliferation, differentiation, growth and repair. Biochemically, these adhesions are composed of diverse, yet an organised group of structural proteins, receptors, adaptors, various enzymes including protein kinases, phosphatases, GTPases, proteases, etc. as well as scaffolding molecules. The major integrin adhesion complexes (IACs) characterised are focal adhesions (FAs), invadosomes (podosomes and invadopodia), hemidesmosomes (HDs) and reticular adhesions (RAs). The varied composition and regulation of the IACs and their signalling, apart from being an integral part of normal cell survival, has been shown to be of paramount importance in various developmental and pathological processes. This review per-illustrates the recent advancements in the research of IACs, their crucial roles in normal as well as diseased states. We have also touched on few of the various methods that have been developed over the years to visualise IACs, measure the forces they exert and study their signalling and molecular composition. Having such pertinent roles in the context of various pathologies, these IACs need to be understood and studied to develop therapeutical targets. We have given an update to the studies done in recent years and described various techniques which have been applied to study these structures, thereby, providing context in furthering research with respect to IAC targeted therapeutics.

Short linear motif candidates in the cell entry system used by SARS-CoV-2 and their potential therapeutic implications

The first reported receptor for SARS-CoV-2 on host cells was the angiotensin-converting enzyme 2 (ACE2). However, the viral spike protein also has an RGD motif, suggesting that cell surface integrins may be co-receptors. We examined the sequences of ACE2 and integrins with the Eukaryotic Linear Motif (ELM) resource and identified candidate short linear motifs (SLiMs) in their short, unstructured, cytosolic tails with potential roles in endocytosis, membrane dynamics, autophagy, cytoskeleton, and cell signaling. These SLiM candidates are highly conserved in vertebrates and may interact with the μ2 subunit of the endocytosis-associated AP2 adaptor complex, as well as with various protein domains (namely, I-BAR, LC3, PDZ, PTB, and SH2) found in human signaling and regulatory proteins. Several motifs overlap in the tail sequences, suggesting that they may act as molecular switches, such as in response to tyrosine phosphorylation status. Candidate LC3-interacting region (LIR) motifs are present in the tails of integrin β3 and ACE2, suggesting that these proteins could directly recruit autophagy components. Our findings identify several molecular links and testable hypotheses that could uncover mechanisms of SARS-CoV-2 attachment, entry, and replication against which it may be possible to develop host-directed therapies that dampen viral infection and disease progression. Several of these SLiMs have now been validated to mediate the predicted peptide interactions.

NRP2 as an Emerging Angiogenic Player; Promoting Endothelial Cell Adhesion and Migration by Regulating Recycling of α5 Integrin

Angiogenesis relies on the ability of endothelial cells (ECs) to migrate over the extracellular matrix via integrin receptors to respond to an angiogenic stimulus. Of the two neuropilin (NRP) orthologs to be identified, both have been reported to be expressed on normal blood and lymphatic ECs, and to play roles in the formation of blood and lymphatic vascular networks during angiogenesis. Whilst the role of NRP1 and its interactions with integrins during angiogenesis has been widely studied, the role of NRP2 in ECs is poorly understood. Here we demonstrate that NRP2 promotes Rac-1 mediated EC adhesion and migration over fibronectin (FN) matrices in a mechanistically distinct fashion to NRP1, showing no dependence on β3 integrin (ITGB3) expression, or VEGF stimulation. Furthermore, we highlight evidence of a regulatory crosstalk between NRP2 and α5 integrin (ITGA5) in ECs, with NRP2 depletion eliciting an upregulation of ITGA5 expression and disruptions in ITGA5 cellular organization. Finally, we propose a mechanism whereby NRP2 promotes ITGA5 recycling in ECs; NRP2 depleted ECs were found to exhibit reduced levels of total ITGA5 subunit recycling compared to wild-type (WT) ECs. Our findings expose NRP2 as a novel angiogenic player by promoting ITGA5-mediated EC adhesion and migration on FN.

Sorafenib Inhibits Proliferation, Migration and Invasion of Breast Cancer Cells

INTRODUCTION

Metastatic breast cancer has poor prognosis due to limited therapeutic options. Protein kinase dysregulations have a major role in breast cancer progression and metastasis. In this study, we investigated the anti-cancer activity of sorafenib, a multikinase inhibitor, which targets receptor tyrosine kinases in breast cancer. Although treatment with sorafenib has increased the patient survival and inhibited metastatic migration in hepatocellular carcinoma, its role in breast cancer migration, metastasis, and intracellular signaling modulation is unknown.

METHODS

Breast cancer cell lines MCF7 and MDA-MB-231 were treated with sorafenib and its effect on proliferation, migration, invasion and gene expression was analyzed.

RESULTS

We found that sorafenib has an anti-proliferative and cytotoxic effect on breast cancer cells. Importantly, sorafenib inhibited the migration and invasion of breast cancer cells in vitro. Mechanistically, sorafenib increased mitochondrial superoxide production, suppressed breast cancer stem cell self-renewal, inhibited epithelial mesenchymal transition and ERK signaling.

CONCLUSION

Thus, sorafenib has anti-cancer activity against breast cancer cells and could improve the survival of breast cancer patients by inhibiting their invasive and metastatic properties.

Neuropilin: Handyman and Power Broker in the Tumor Microenvironment

Neuropilin-1 and neuropilin-2 form a small family of transmembrane receptors, which, due to the lack of a cytosolic protein kinase domain, act primarily as co-receptors for various ligands. Performing at the molecular level both the executive and organizing functions of a handyman as well as of a power broker, they are instrumental in controlling the signaling of various receptor tyrosine kinases, integrins, and other molecules involved in the regulation of physiological and pathological angiogenic processes. In this setting, the various neuropilin ligands and interaction partners on various cells of the tumor microenvironment, such as cancer cells, endothelial cells, cancer-associated fibroblasts, and immune cells, are surveyed. The suitability of various neuropilin-targeting substances and the intervention in neuropilin-mediated interactions is considered as a possible building block of tumor therapy.

Integrin Signaling in Cancer: Mechanotransduction, Stemness, Epithelial Plasticity, and Therapeutic Resistance

Integrins mediate cell adhesion and transmit mechanical and chemical signals to the cell interior. Various mechanisms deregulate integrin signaling in cancer, empowering tumor cells with the ability to proliferate without restraint, to invade through tissue boundaries, and to survive in foreign microenvironments. Recent studies have revealed that integrin signaling drives multiple stem cell functions, including tumor initiation, epithelial plasticity, metastatic reactivation, and resistance to oncogene- and immune-targeted therapies. Here, we discuss the mechanisms leading to the deregulation of integrin signaling in cancer and its various consequences. We place emphasis on novel functions, determinants of context dependency, and mechanism-based therapeutic opportunities.

Neuropilins in the Context of Tumor Vasculature

Neuropilin-1 and Neuropilin-2 form a small family of plasma membrane spanning receptors originally identified by the binding of semaphorin and vascular endothelial growth factor. Having no cytosolic protein kinase domain, they function predominantly as co-receptors of other receptors for various ligands. As such, they critically modulate the signaling of various receptor tyrosine kinases, integrins, and other molecules involved in the regulation of physiological and pathological angiogenic processes. This review highlights the diverse neuropilin ligands and interacting partners on endothelial cells, which are relevant in the context of the tumor vasculature and the tumor microenvironment. In addition to tumor cells, the latter contains cancer-associated fibroblasts, immune cells, and endothelial cells. Based on the prevalent neuropilin-mediated interactions, the suitability of various neuropilin-targeted substances for influencing tumor angiogenesis as a possible building block of a tumor therapy is discussed.

VEGF/Neuropilin Signaling in Cancer Stem Cells

The function of vascular endothelial growth factor (VEGF) in cancer extends beyond angiogenesis and vascular permeability. Specifically, VEGF-mediated signaling occurs in tumor cells and this signaling contributes to key aspects of tumorigenesis including the self-renewal and survival of cancer stem cells (CSCs). In addition to VEGF receptor tyrosine kinases, the neuropilins (NRPs) are critical for mediating the effects of VEGF on CSCs, primarily because of their ability to impact the function of growth factor receptors and integrins. VEGF/NRP signaling can regulate the expression and function of key molecules that have been implicated in CSC function including Rho family guanosine triphosphatases (GTPases) and transcription factors. The VEGF/NRP signaling axis is a prime target for therapy because it can confer resistance to standard chemotherapy, which is ineffective against most CSCs. Indeed, several studies have shown that targeting either NRP1 or NRP2 can inhibit tumor initiation and decrease resistance to other therapies.

Convergence of VEGF and YAP/TAZ signaling: Implications for angiogenesis and cancer biology

Vascular endothelial growth factor (VEGF) stimulates endothelial cells to promote both developmental and pathological angiogenesis. VEGF also directly affects tumor cells and is associated with the initiation, progression, and recurrence of tumors, as well as the emergence and maintenance of cancer stem cells (CSCs). Studies have uncovered the importance of the transcriptional regulators YAP and TAZ in mediating VEGF signaling. For example, VEGF stimulates the GTPase activity of Rho family members and thereby alters cytoskeletal dynamics, which contributes to the activation of YAP and TAZ. In turn, YAP- and TAZ-mediated changes in gene expression sustain Rho family member activity and cytoskeletal effects to promote both vascular growth and remodeling in endothelial cells and the acquisition of stem-like traits in tumor cells. In this Review, we discuss how these findings further explain the pathophysiological roles of VEGF and YAP/TAZ, identify their connections to other receptor-mediated pathways, and reveal ways of therapeutically targeting their convergent signals in patients.

Lipid rafts regulate the lamellipodia formation of melanoma A375 cells via actin cytoskeleton-mediated recruitment of β1 and β3 integrin

Lipid rafts, distinct liquid-ordered plasma membrane microdomains, have been shown to regulate tumor cell migration by internalizing and recycling cell-surface proteins. The present study reports that lipid rafts are a prerequisite for lamellipodia formation, which is the first step in the processes of tumor cell migration. The results from the wound-healing assay and immunostaining indicated that lipid rafts were asymmetrically distributed to the leading edge of migrating melanoma A375 cells during lamellipodia formation. When the integrity of lipids rafts was disrupted, lamellipodia formation was inhibited. The investigation of possible molecular mechanisms indicated that lipid rafts recruited β1 and β3 integrins, two important adhesion proteins for cell migration, to the lamellipodia. However, the different distribution characteristics of β1 and β3 integrins implied disparate functions in lamellipodia formation. Further immunostaining experiments showed that the actin cytoskeleton was responsible for lipid raft-mediated β1 and β3 integrin distribution in the lamellipodia. Together, these findings provide novel insights into the regulation of lipid rafts in lamellipodia formation, and suggest that lipid rafts may be novel and attractive targets for cancer therapy.

Neuropilin-2 regulates airway inflammatory responses to inhaled lipopolysaccharide

Neuropilins are multifunctional receptors that play important roles in immune regulation. Neuropilin-2 (NRP2) is expressed in the lungs, but whether it regulates airway immune responses is unknown. Here, we report that Nrp2 is weakly expressed by alveolar macrophages (AMs) in the steady state but is dramatically upregulated following in vivo lipopolysaccharide (LPS) inhalation. Ex vivo treatment of human AMs with LPS also increased NRP2 mRNA expression and cell-surface display of NRP2 protein. LPS-induced Nrp2 expression in AMs was dependent upon the myeloid differentiation primary response 88 signaling pathway and the transcription factor NF-κB. In addition to upregulating display of NRP2 on the cell membrane, inhaled LPS also triggered AMs to release soluble NRP2 into the airways. Finally, myeloid-specific ablation of NRP2 resulted in increased expression of the chemokine (C-C motif) ligand 2 ( Ccl2) in the lungs and prolonged leukocyte infiltration in the airways following LPS inhalation. These findings suggest that NRP2 expression by AMs regulates LPS-induced inflammatory cell recruitment to the airways and reveal a novel role for NRP2 during innate immune responses in the lungs.

NRP-2 in tumor lymphangiogenesis and lymphatic metastasis

Neuropilin-2 (NRP-2) not only functions as a receptor for semaphorins, a family of neural axon guidance factors, but also interacts with VEGFs, a family of vascular endothelial growth factors. As an independent receptor or a co-receptor, NRP-2 binds to ligands VEGF-C/D, activates the VEGF-C/D-NRP-2 signaling axis, and further regulates lymphangiogenesis-associated factors in both lymphatic endothelial cells (LECs) and some tumor cells during tumor progression. Via VEGF-C/D-NRP-2 axis, NRP-2 induces LEC proliferation, reconstruction and lymphangiogenesis and subsequently promotes tumor cell migration, invasion and lymphatic metastasis. There are similarities and differences among NRP-1, NRP-2 and VEGFR-3 in chemical structure, ligand specificity, chromosomal location, soluble protein forms, cellular functions and expression profiles. High expression of NRP-2 in LECs and tumor cells has been observed in different anatomic sites, histological patterns and progression stages of various tumors, especially during tumor lymphangiogenesis and lymphatic metastasis, and therefore the NRP-2 and VEGF-C/D-NRP-2 axis are closely related to tumor development, progression, invasion, and metastasis. In addition, it is important for prognosis of tumor. The studies on NRP-2 targeted therapy have recently achieved some successes, utilizing NRP-2 blocking antibodies, NRP-2 inhibitory peptides, soluble NRP-2 antagonists, small molecule inhibitors and various NRP-2 gene therapeutic strategies.

Impact of mesenchymal stem cells' secretome on glioblastoma pathophysiology

Background

Glioblastoma (GBM) is a highly aggressive primary brain cancer, for which curative therapies are not available. An emerging therapeutic approach suggested to have potential to target malignant gliomas has been based on the use of multipotent mesenchymal stem cells (MSCs), either unmodified or engineered to deliver anticancer therapeutic agents, as these cells present an intrinsic capacity to migrate towards malignant tumors. Nevertheless, it is still controversial whether this innate tropism of MSCs towards the tumor area is associated with cancer promotion or suppression. Considering that one of the major mechanisms by which MSCs interact with and modulate tumor cells is via secreted factors, we studied how the secretome of MSCs modulates critical hallmark features of GBM cells.

Methods

The effect of conditioned media (CM) from human umbilical cord perivascular cells (HUCPVCs, a MSC population present in the Wharton’s jelly of the umbilical cord) on GBM cell viability, migration, proliferation and sensitivity to temozolomide treatment of U251 and SNB-19 GBM cells was evaluated. The in vivo chicken chorioallantoic membrane (CAM) assay was used to evaluate the effect of HUCPVCs CM on tumor growth and angiogenesis. The secretome of HUCPVCs was characterized by proteomic analyses.

Results

We found that both tested GBM cell lines exposed to HUCPVCs CM presented significantly higher cellular viability, proliferation and migration. In contrast, resistance of GBM cells to temozolomide chemotherapy was not significantly affected by HUCPVCs CM. In the in vivo CAM assay, CM from HUCPVCs promoted U251 and SNB-19 tumor cells growth. Proteomic analysis to characterize the secretome of HUCPVCs identified several proteins involved in promotion of cell survival, proliferation and migration, revealing novel putative molecular mediators for the effects observed in GBM cells exposed to HUCPVCs CM.

Conclusions

These findings provide novel insights to better understand the interplay between GBM cells and MSCs, raising awareness to potential safety issues regarding the use of MSCs as stem-cell based therapies for GBM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1303-8) contains supplementary material, which is available to authorized users.

A radial axis defined by semaphorin-to-neuropilin signaling controls pancreatic islet morphogenesis

The islets of Langerhans are endocrine organs characteristically dispersed throughout the pancreas. During development, endocrine progenitors delaminate, migrate radially and cluster to form islets. Despite the distinctive distribution of islets, spatially localized signals that control islet morphogenesis have not been discovered. Here, we identify a radial signaling axis that instructs developing islet cells to disperse throughout the pancreas. A screen of pancreatic extracellular signals identified factors that stimulated islet cell development. These included semaphorin 3a, a guidance cue in neural development without known functions in the pancreas. In the fetal pancreas, peripheral mesenchymal cells expressed Sema3a, while central nascent islet cells produced the semaphorin receptor neuropilin 2 (Nrp2). Nrp2 mutant islet cells developed in proper numbers, but had defects in migration and were unresponsive to purified Sema3a. Mutant Nrp2 islets aggregated centrally and failed to disperse radially. Thus, Sema3a-Nrp2 signaling along an unrecognized pancreatic developmental axis constitutes a chemoattractant system essential for generating the hallmark morphogenetic properties of pancreatic islets. Unexpectedly, Sema3a- and Nrp2-mediated control of islet morphogenesis is strikingly homologous to mechanisms that regulate radial neuronal migration and cortical lamination in the developing mammalian brain.

α6β4 Integrin Regulates the Collective Migration of Epithelial Cells

α₆β₄ integrin is localized in a unique punctate distribution at the cell-substratum interface along the leading front of single, front-rear-polarized A549 cells. These puncta are interspersed between focal adhesions and lack association with the actin cytoskeleton. Knockdown of β₄ integrin in A549 cells inhibits their directed migration, with knockdown cells exhibiting large focal adhesions and reduced actin dynamics. Despite these changes, the speed of knockdown cells is equivalent to control cells. Interestingly, in such cells, α₆ integrin retains its punctate distribution. Moreover, in β₄ integrin knockdown cells, we observe a loss of β₁ integrin from focal adhesions and an enhanced association with α₆ integrin. We confirmed the switch in the β integrin binding partner of α₆ integrin in the knockdown cells by immunoprecipitation. We next investigated the role of β₄ integrin in collective cell migration. Wounded monolayers of β₄ integrin knockdown cells exhibit reduced collective migration compared with controls. When we forced expression of β₄ integrin in the leader cells of wounded monolayers, collective migration was restored. Similarly, forced expression of β₄ integrin in primary rat alveolar epithelial cells also promotes collective cell migration. In addition, we interrogated the pathway by which β₄ integrin regulates A549 cell-directed migration. Constitutively active Ras-related C3 botulinum toxin substrate 1 rescues motility defects resulting from β₄ integrin deficiency. Together, our results support the hypothesis that α₆β₄ integrin is a positive regulator of collective cell migration of A549 cells through influence on signal pathways in leader cells.

The formation of quiescent glomerular endothelial cell monolayer in vitro is strongly dependent on the choice of extracellular matrix coating

BACKGROUND AND AIMS

Nephropathy involves pathophysiological changes to the glomerulus. The primary glomerular endothelial cells (GEnCs) have emerged as an important tool for studying glomerulosclerotic mechanisms and in the screening process for drug-candidates. The success of the studies is dependent on the quality of the cell model. Therefore, we set out to establish an easy, reproducible model of the quiescent endothelial monolayer with the use of commercially available extracellular matrices (ECMs).

METHODS

Primary hGEnCs were seeded on various ECMs. Cell adhesion was monitored by an impedance sensing system. The localization of junctional proteins was assessed by immunofluorescence and the barrier function by passage of fluorescent dextrans and magnitude of VEGF response.

RESULTS

All ECM matrices except recombinant human laminin 111 (rhLN111) supported comparable cell proliferation. Culturing hGEnCs on rhLN521, rhLN511 or fibronectin resulted in a physiologically relevant barrier to 70kDa dextrans which was 82% tighter than that formed on collagen type IV. Furthermore, only hGEnCs cultured on rhLN521 or rhLN511 showed plasma-membrane localized zonula occludens-1 and vascular endothelial cadherin indicative of proper tight and adherens junctions (AJ).

CONCLUSION

We recommend culturing hGEnCs on the mature glomerular basement membrane laminin - rhLN521 - which, as the only commercially available ECM, promotes all of the characteristics of the quiescent hGEnC monolayer: cobblestone morphology, well-defined AJs and physiological perm-selectivity.

Plasticity of tumor cell invasion: governance by growth factors and cytokines

Tumor cell migration, the basis for metastatic dissemination, is an adaptive process which depends upon coordinated cell interaction with the environment, influencing cell-matrix and cell-cell adhesion, cytoskeletal dynamics and extracellular matrix remodeling. Growth factors and cytokines, released within the reactive tumor microenvironment and their intracellular effector signals strongly impact mechanocoupling functions in tumor cells and thereby control the mode and extent of tumor invasion, including collective and single-cell migration and their interconversions. Besides their role in controlling tumor cell growth and survival, cytokines and growth factors thus provide complex orchestration of the metastatic cascade and tumor cell adaptation to environmental challenge. We here review the mechanisms by which growth factors and cytokines control the reciprocal interactions between tumor cells and their microenvironment, and the consequences for the efficacy and plasticity of invasion programs and metastasis.

Preparation, Purification, and Identification of a Monoclonal Antibody Against NRP2 b1b2 Domain

First identified as a high-affinity kinase-deficient receptor for class-3 semaphorins and vascular endothelial growth factor (VEGF) families, Neuropilin2 (NRP2) is a transmembrane non-tyrosine-kinase glycoprotein that has a vital function in neuronal patterning. Furthermore, NRP2 expression is often upregulated in cancer tissues and correlated with poor prognosis. In the present study, we report the establishment of a monoclonal antibody specific for NRP2b1b2 domain (NRP2 MAb) through hybridoma method. NRP2 MAb is measured to have a titer of 5.12 × 10(5) against NRP2b1b2 in indirect ELISA. Western blotting, flow cytometry, and immunofluorescence analysis indicate that NRP2 MAb can combine full-length NRP2 in LoVo and SW480 cells. Besides helping further understand NRP2-related pathological mechanisms and cell-signaling pathways, NRP2 MAb may act as a therapeutic agent for cancer in the future.

Neuropilin-2 promotes tumourigenicity and metastasis in oesophageal squamous cell carcinoma through ERK-MAPK-ETV4-MMP-E-cadherin deregulation

Oesophageal squamous cell carcinoma (ESCC) is the most common histological subtype of oesophageal cancer. The disease is particularly prevalent in southern China. The incidence of the disease is on the rise and its overall survival rate remains dismal. Identification and characterization of better molecular markers for early detection and therapeutic targeting are urgently needed. Here, we report levels of transmembrane and soluble neuropilin-2 (NRP2) to be significantly up-regulated in ESCC, and to correlate positively with advanced tumour stage, lymph node metastasis, less favourable R category and worse overall patient survival. NRP2 up-regulation in ESCC was in part a result of gene amplification at chromosome 2q. NRP2 overexpression promoted clonogenicity, angiogenesis and metastasis in ESCC in vitro, while NRP2 silencing by lentiviral knockdown or neutralizing antibody resulted in a contrary effect. This observation was extended in vivo in animal models of subcutaneous tumourigenicity and tail vein metastasis. Mechanistically, overexpression of NRP2 induced expression of ERK MAP kinase and the transcription factor ETV4, leading to enhanced MMP-2 and MMP-9 activity and, as a consequence, suppression of E-cadherin. In summary, NRP2 promotes tumourigenesis and metastasis in ESCC through deregulation of ERK-MAPK-ETV4-MMP-E-cadherin signalling. NRP2 represents a potential diagnostic or prognostic biomarker and therapeutic target for ESCC. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

NRP1 function and targeting in neurovascular development and eye disease

Neuropilin 1 (NRP1) is expressed by neurons, blood vessels, immune cells and many other cell types in the mammalian body and binds a range of structurally and functionally diverse extracellular ligands to modulate organ development and function. In recent years, several types of mouse knockout models have been developed that have provided useful tools for experimental investigation of NRP1 function, and a multitude of therapeutics targeting NRP1 have been designed, mostly with the view to explore them for cancer treatment. This review provides a general overview of current knowledge of the signalling pathways that are modulated by NRP1, with particular focus on neuronal and vascular roles in the brain and retina. This review will also discuss the potential of NRP1 inhibitors for the treatment for neovascular eye diseases.

Astrocytes spatially restrict VEGF signaling by polarized secretion and incorporation of VEGF into the actively assembling extracellular matrix

The spatial organization of vascular endothelial growth factor (VEGF) signaling is a key determinant of vascular patterning during development and tissue repair. How VEGF signaling becomes spatially restricted and the role of VEGF secreting astrocytes in this process remains poorly understood. Using a VEGF-GFP fusion protein and confocal time-lapse microscopy, we observed the intracellular routing, secretion and immobilization of VEGF in scratch-activated living astrocytes. We found VEGF to be directly transported to cell-extracellular matrix attachments where it is incorporated into fibronectin fibrils. VEGF accumulated at β1 integrin containing fibrillar adhesions and was translocated along the cell surface prior to internalization and degradation. We also found that only the astrocyte-derived, matrix-bound, and not soluble VEGF decreases β1 integrin turnover in fibrillar adhesions. We suggest that polarized VEGF release and ECM remodeling by VEGF secreting cells is key to control the local concentration and signaling of VEGF. Our findings highlight the importance of astrocytes in directing VEGF functions and identify these mechanisms as promising target for angiogenic approaches.

Control of cellular motility by neuropilin-mediated physical interactions

The neuropilin (Nrp) family consists of multifunctional cell surface receptors with critical roles in a number of different cell and tissue types. A core aspect of Nrp function is in ligand-dependent cellular migration, where it controls the multistep process of cellular motility through integration of ligand binding and receptor signaling. At a molecular level, the role of Nrp in migration is intimately connected to the control of adhesive interactions and cytoskeletal reorganization. Here, we review the physiological role of Nrp in cellular adhesion and motility in the cardiovascular and nervous systems. We also discuss the emerging pathological role of Nrp in tumor cell migration and metastasis, providing motivation for continued efforts toward developing Nrp inhibitors.

Neuropilin Functions as an Essential Cell Surface Receptor

The Neuropilins (Nrps) are a family of essential cell surface receptors involved in multiple fundamental cellular signaling cascades. Nrp family members have key functions in VEGF-dependent angiogenesis and semaphorin-dependent axon guidance, controlling signaling and cross-talk between these fundamental physiological processes. More recently, Nrp function has been found in diverse signaling and adhesive functions, emphasizing their role as pleiotropic co-receptors. Pathological Nrp function has been shown to be important in aberrant activation of both canonical and alternative pathways. Here we review key recent insights into Nrp function in human health and disease.

The potential of class 3 semaphorins as both targets and therapeutics in cancer

INTRODUCTION

Semaphorins have been originally identified as a family of evolutionary conserved soluble or membrane-associated proteins involved in diverse developmental phenomena. This family of proteins profoundly influences numerous pathophysiological processes, including organogenesis, cardiovascular development and immune response. Apart from steering the neural networking process, these are implicated in a broad range of biological operations including regulation of tumor progression and angiogenesis.

AREAS COVERED

Members of class 3 semaphorin family are known to modulate various cellular processes involved in malignant transformation. Some of the family members trigger diverse signaling processes involved in tumor progression and angiogenesis by binding with plexin and neuropilin. A better understanding of the various signaling mechanisms by which semaphorins modulate tumor progression and angiogenesis may serve as crucial tool in crafting new semaphorin-based anticancer therapy. These include treatment with recombinant tumor suppressive semaphorins or inhibition of tumor-promoting semaphorins by their specific siRNAs, small-molecule inhibitors or specific receptors using neutralizing antibodies or blocking peptides that might serve as novel strategies for effective management of cancers.

EXPERT OPINION

This review focuses on all the possible avenues to explore various members of class 3 semaphorin family to serve as therapeutics for combating cancer.

The emerging role of class-3 semaphorins and their neuropilin receptors in oncology

The semaphorins, discovered over 20 years ago, are a large family of secreted or transmembrane and glycophosphatidylinositol -anchored proteins initially identified as axon guidance molecules crucial for the development of the nervous system. It has now been established that they also play important roles in organ development and function, especially involving the immune, respiratory, and cardiovascular systems, and in pathological disorders, including cancer. During tumor progression, semaphorins can have both pro- and anti-tumor functions, and this has created complexities in our understanding of these systems. Semaphorins may affect tumor growth and metastases by directly targeting tumor cells, as well as indirectly by interacting with and influencing cells from the micro-environment and vasculature. Mechanistically, semaphorins, through binding to their receptors, neuropilins and plexins, affect pathways involved in cell adhesion, migration, invasion, proliferation, and survival. Importantly, neuropilins also act as co-receptors for several growth factors and enhance their signaling activities, while class 3 semaphorins may interfere with this. In this review, we focus on the secreted class 3 semaphorins and their neuropilin co-receptors in cancer, including aspects of their signaling that may be clinically relevant.

Semaphorins in cardiovascular medicine

During organogenesis, patterning is primarily achieved by the combined actions of morphogens. Among these, semaphorins represent a general system for establishing the appropriate wiring architecture of biological nets. Originally discovered as evolutionarily conserved steering molecules for developing axons, subsequent studies on semaphorins expanded their functions to the cardiovascular and immune systems. Semaphorins participate in cardiac organogenesis and control physiological vasculogenesis and angiogenesis, which result from a balance between pro- and anti-angiogenic signals. These signals are altered in several diseases. In this review, we discuss the role of semaphorins in vascular biology, emphasizing the mechanisms by which these molecules control vascular patterning and lymphangiogenesis, as well as in genetically inherited and degenerative vascular diseases.

The multifaceted activity of VEGF in angiogenesis - Implications for therapy responses

Vascular endothelial growth factor (VEGF) is a key growth factor driving angiogenesis (i.e. the formation of new blood vessels) in health and disease. Pharmacological blockade of VEGF signaling to inhibit tumor angiogenesis is clinically approved but the survival benefit is limited as patients invariably acquire resistance. This is partially mediated by the intrinsic flexibility of tumor cells to adapt to VEGF-blockade. However, it has become clear that tumor stromal cells also contribute to the resistance. Originally, VEGF was thought to specifically target endothelial cells (ECs) but it is now clear that many stromal cells also respond to VEGF signaling, making anti-VEGF therapy more complex than initially anticipated. A more comprehensive understanding of the complex responses of stromal cells to VEGF-blockade might inform the design of improved anti-angiogenic agents.

Conformational remodeling of the fibronectin matrix selectively regulates VEGF signaling

The fibronectin matrix plays a crucial role in the regulation of angiogenesis during development, tissue repair and pathogenesis. Previous work has identified a fibronectin-derived homophilic binding peptide, anastellin, as an effective inhibitor of angiogenesis; however, its mechanism of action is not well understood. In the present study, we demonstrate that anastellin selectively inhibits microvessel cell signaling in response to the VEGF165 isoform, but not VEGF121, by preventing the assembly of the complex containing the VEGF receptor and neuropilin-1. Anastellin treatment resulted in the inactivation of α5β1 integrins but was not accompanied by a change in either adhesion complexes or adhesion-based signaling. Integrin inactivation was associated with a masking of the fibronectin synergy site within the extracellular matrix (ECM), indicating that α5β1 inactivation resulted from a decrease in available ligand. These data demonstrate that anastellin influences the microvessel cell response to growth factors by controlling the repertoire of ligated integrins and point to anastellin as an effective regulator of fibronectin matrix organization. These studies further suggest that homophilic fibronectin binding peptides might have novel applications in the field of tissue regeneration as tools to regulate neovascularization.

Neuropilin-2 and its ligand VEGF-C predict treatment response after transurethral resection and radiochemotherapy in bladder cancer patients

The standard treatment for invasive bladder cancer is radical cystectomy. In selected patients, bladder-sparing therapy can be performed by transurethral resection (TURBT) and radio-chemotherapy (RCT) or radiotherapy (RT). Our published in vitro data suggest that the Neuropilin-2 (NRP2)/VEGF-C axis plays a role in therapy resistance. Therefore, we studied the prognostic impact of NRP2 and VEGF-C in 247 bladder cancer patients (cN0M0) treated with TURBT and RCT (n = 198) or RT (n = 49) and a follow-up time up to 15 years. A tissue microarray was analyzed by immunohistochemistry. NRP2 expression emerged as a prognostic factor in overall survival (OS; HR: 3.42; 95% CI: 1.48 - 7.86; p = 0.004) and was associated with a 3.85-fold increased risk of an early cancer specific death (95% CI: 0.91 - 16.24; p = 0.066) in multivariate analyses. Cancer specific survival (CSS) dropped from 166 months to 85 months when NRP2 was highly expressed (p = 0.037). Patients with high VEGF-C expression have a 2.29-fold increased risk of shorter CSS (95% CI: 1.03-5.35; p = 0.043) in univariate analysis. CSS dropped from 170 months to 88 months in the case of high VEGF-C expression (p = 0.041). Additionally, NRP2 and VEGF-C coexpression is a prognostic marker for OS in multivariate models (HR: 7.54; 95% CI: 1.57-36.23; p = 0.012). Stratification for muscle invasiveness (T1 vs. T2-T4) confirmed the prognostic role of NRP2 and NRP2/VEGF-C co-expression in patients with T2-T4 but also with high risk T1 disease. In conclusion, immunohistochemistry for NRP2 and VEGF-C has been determined to predict therapy outcome in bladder cancer patients prior to TURBT and RCT.

Bacterial proteins and peptides in cancer therapy: today and tomorrow

Cancer is one of the most deadly diseases worldwide. In the last three decades many efforts have been made focused on understanding how cancer grows and responds to drugs. The dominant drug-development paradigm has been the "one drug, one target." Based on that, the two main targeted therapies developed to combat cancer include the use of tyrosine kinase inhibitors and monoclonal antibodies. Development of drug resistance and side effects represent the major limiting factors for their use in cancer treatment. Nowadays, a new paradigm for cancer drug discovery is emerging wherein multi-targeted approaches gain ground in cancer therapy. Therefore, to overcome resistance to therapy, it is clear that a new generation of drugs is urgently needed. Here, regarding the concept of multi-targeted therapy, we discuss the challenges of using bacterial proteins and peptides as a new generation of effective anti-cancer drugs.

Regulated splicing of the α6 integrin cytoplasmic domain determines the fate of breast cancer stem cells

Although the α6β1 integrin has been implicated in the function of breast and other cancer stem cells (CSCs), little is known about its regulation and relationship to mechanisms involved in the genesis of CSCs. We report that a CD44(high)/CD24(low) population, enriched for CSCs, is comprised of distinct epithelial and mesenchymal populations that differ in expression of the two α6 cytoplasmic domain splice variants: α6A and α6B. α6Bβ1 expression defines the mesenchymal population and is necessary for CSC function, a function that cannot be executed by α6A integrins. The generation of α6Bβ1 is tightly controlled and occurs as a consequence of an autocrine vascular endothelial growth factor (VEGF) signaling that culminates in the transcriptional repression of a key RNA-splicing factor. These data alter our understanding of how α6β1 contributes to breast cancer, and they resolve ambiguities regarding the use of total α6 (CD49f) expression as a biomarker for CSCs.

Identification of co-expressed gene signatures in mouse B1, marginal zone and B2 B-cell populations

In mice, three major B-cell subsets have been identified with distinct functionalities: B1 B cells, marginal zone B cells and follicular B2 B cells. Here, we used the growing body of publicly available transcriptomics data to create an expression atlas of 84 gene expression microarray data sets of distinct mouse B-cell subsets. These data were subjected to network-based cluster analysis using BioLayout Express(3D). Using this analysis tool, genes with related functions clustered together in discrete regions of the network graph and enabled the identification of transcriptional networks that underpinned the functional activity of distinct cell populations. Some gene clusters were expressed highly by most of the cell populations included in this analysis (such as those with activity related to house-keeping functions). Others contained genes with expression patterns specific to distinct B-cell subsets. While these clusters contained many genes typically associated with the activity of the cells they were specifically expressed in, many novel B-cell-subset-specific candidate genes were identified. A large number of uncharacterized genes were also represented in these B-cell lineage-specific clusters. Further analysis of the activities of these uncharacterized candidate genes will lead to the identification of novel B-cell lineage-specific transcription factors and regulators of B-cell function. We also analysed 36 microarray data sets from distinct human B-cell populations. These data showed that mouse and human germinal centre B cells shared similar transcriptional features, whereas mouse B1 B cells were distinct from proposed human B1 B cells.

VEGF targets the tumour cell

The function of vascular endothelial growth factor (VEGF) in cancer is not limited to angiogenesis and vascular permeability. VEGF-mediated signalling occurs in tumour cells, and this signalling contributes to key aspects of tumorigenesis, including the function of cancer stem cells and tumour initiation. In addition to VEGF receptor tyrosine kinases, the neuropilins are crucial for mediating the effects of VEGF on tumour cells, primarily because of their ability to regulate the function and the trafficking of growth factor receptors and integrins. This has important implications for our understanding of tumour biology and for the development of more effective therapeutic approaches.

miR-331-3p regulates expression of neuropilin-2 in glioblastoma

Aberrant expression of microRNAs (miRNAs), a class of small non-coding regulatory RNAs, has been implicated in the development and progression of high-grade gliomas. However, the precise mechanistic role of many miRNAs in this disease remains unclear. Here, we investigate the functional role of miR-331-3p in glioblastoma multiforme (GBM). We found that miR-331-3p expression in GBM cell lines is significantly lower than in normal brain, and that transient overexpression of miR-331-3p inhibits GBM cell line proliferation and clonogenic growth, suggesting a possible tumor suppressor role for miR-331-3p in this system. Bioinformatics analysis identified neuropilin-2 (NRP-2) as a putative target of miR-331-3p. Using transfection studies, we validated NRP-2 mRNA as a target of miR-331-3p in GBM cell lines, and show that NRP-2 expression is regulated by miR-331-3p. RNA interference (RNAi) to inhibit NRP-2 expression in vitro decreased the growth and clonogenic growth of GBM cell lines, providing further support for an oncogenic role for NRP-2 in high-grade gliomas. We also show that miR-331-3p inhibits GBM cell migration, an effect due in part to reduced NRP-2 expression. Finally, we identified a significant inverse correlation between miR-331-3p and NRP-2 expression in The Cancer Genome Atlas GBM cohort of 491 patients. Together, our results suggest that a loss of miR-331-3p expression contributes to GBM development and progression, at least in part via upregulating NRP-2 expression and increasing cell proliferation and clonogenic growth.

The cytoplasmic domain of neuropilin-1 regulates focal adhesion turnover

Though the vascular endothelial growth factor coreceptor neuropilin-1 (Nrp1) plays a critical role in vascular development, its precise function is not fully understood. We identified a group of novel binding partners of the cytoplasmic domain of Nrp1 that includes the focal adhesion regulator, Filamin A (FlnA). Endothelial cells (ECs) expressing a Nrp1 mutant devoid of the cytoplasmic domain (nrp1(cyto)(Δ/Δ)) migrated significantly slower in response to VEGF relative to the cells expressing wild-type Nrp1 (nrp1(+/+) cells). The rate of FA turnover in VEGF-treated nrp1(cyto)(Δ/Δ) ECs was an order of magnitude lower in comparison to nrp1(+/+) ECs, thus accounting for the slower migration rate of the nrp1(cyto)(Δ/Δ) ECs.