Neuropilins: a new target for cancer therapy

Target specification and therapeutic potential of extracellular vesicles for regulating corneal angiogenesis, lymphangiogenesis, and nerve repair

Extracellular vesicles, including exosomes, are small extracellular vesicles that range in size from 30 nm to 10 μm in diameter and have specific membrane markers. They are naturally secreted and are present in various bodily fluids, including blood, urine, and saliva, and through the variety of their internal cargo, they contribute to both normal physiological and pathological processes. These processes include immune modulation, neuronal synapse formation, cell differentiation, cancer metastasis, angiogenesis, lymphangiogenesis, progression of infectious disease, and neurodegenerative disorders like Alzheimer's and Parkinson's disease. In recent years, interest has grown in the use of exosomes as a potential drug delivery system for various diseases and injuries. Importantly, exosomes originating from a patient's own cells exhibit minimal immunogenicity and possess remarkable stability along with inherent and adjustable targeting capabilities. This review explores the roles of exosomes in angiogenesis, lymphangiogenesis, and nerve repair with a specific emphasis on these processes within the cornea. Furthermore, it examines exosomes derived from specific cell types, discusses the advantages of exosome-based therapies in modulating these processes, and presents some of the most established methods for exosome isolation. Exosome-based treatments are emerging as potential minimally invasive and non-immunogenic therapies that modulate corneal angiogenesis and lymphangiogenesis, as well as enhance and accelerate endogenous corneal nerve repair.

New Salicylanilide Derivatives and Their Peptide Conjugates as Anticancer Compounds: Synthesis, Characterization, and In Vitro Effect on Glioblastoma

Pharmacologically active salicylanilides (2-hydroxy-N-phenylbenzamides) have been a promising area of interest in medicinal chemistry-related research for quite some time. This group of compounds has shown a wide spectrum of biological activities, including but not limited to anticancer effects. In this study, substituted salicylanilides were chosen to evaluate the in vitro activity on U87 human glioblastoma (GBM) cells. The parent salicylanilide, salicylanilide 5-chloropyrazinoates, a 4-aminosalicylic acid derivative, and the new salicylanilide 4-formylbenzoates were chemically and in vitro characterized. To enhance the internalization of the compounds, they were conjugated to delivery peptides with the formation of oxime bonds. Oligotuftsins ([TKPKG]n, n = 1-4), the ligands of neuropilin receptors, were used as GBM-targeting carrier peptides. The in vitro cellular uptake, intracellular localization, and penetration ability on tissue-mimicking models of the fluorescent peptide derivatives were determined. The compounds and their peptide conjugates significantly decreased the viability of U87 glioma cells. Salicylanilide compound-induced GBM cell death was associated with activation of autophagy, as characterized by immunodetection of autophagy-related processing of light chain 3 protein.

Neuropilin-2 acts a critical determinant for epithelial-to-mesenchymal transition and aggressive behaviors of human head and neck cancer

PURPOSE

Neuropilin-2 (NRP2) is a multifunctional single-pass transmembrane receptor that binds to two disparate ligands, namely, vascular endothelial growth factors (VEGFs) and semaphorins (SEMAs). It is reportedly involved in neuronal and vascular development. In this study, we uncovered the exact functional role of NRP2 and its molecular mechanism during aggressive behaviors and lymph node (LN) metastasis in human head and neck cancer (HNC) and identified algal methanol extract as a potential novel NRP2 inhibitor.

METHODS

In silico analyses and immunohistochemistry were used to investigate the relationship between NRP2 expression and the prognosis of HNC patients. The functional role of NRP2 on the proliferation, migration, invasion, and cancer stem cell (CSC) properties of HNC cells was examined by MTS, soft agar, clonogenic, transwell migration and invasion assays, and sphere formation assays. Signaling explorer antibody array, western blot, and qPCR were performed toward the investigation of a molecular mechanism that is related to NRP2.

RESULTS

NRP2 was highly expressed in HNC and positively correlated with LN metastasis and advanced tumor stage and size in patients. Using loss- or gain-of-function approaches, we found that NRP2 promoted the proliferative, migratory, and invasive capacities of human HNC cells. Furthermore, NRP2 regulated Sox2 expression to exhibit aggressiveness and CSC properties of human HNC cells. We demonstrated that p90 ribosomal S6 kinase 1 (RSK1) elevates the aggressiveness and CSC properties of human HNC cells, possibly by mediating NRP2 and Sox2. Zeb1 was necessary for executing the NRP2/RSK1/Sox2 signaling pathway during the induction of epithelial-to-mesenchymal transition (EMT) and aggressive behaviors of human HNC cells. Moreover, the methanol extract of Codium fragile (MECF) repressed NRP2 expression, inhibiting the RSK1/Sox2/Zeb1 axis, which contributed to the reduction of aggressive behaviors of human HNC cells.

CONCLUSIONS

These findings suggest that NRP2 is a critical determinant in provoking EMT and aggressive behaviors in human HNC through the RSK1/Sox2/Zeb1 axis, and MECF may have the potential to be a novel NRP2 inhibitor for treating metastasis in HNC patients.

Revealing neuropilin expression patterns in pancreatic cancer: From single‑cell to therapeutic opportunities (Review)

Pancreatic cancer, one of the most fatal types of human cancers, includes several non-epithelial and stromal components, such as activated fibroblasts, vascular cells, neural cells and immune cells, that are involved in different cancers. Vascular endothelial cell growth factor 165 receptors 1 [neuropilin-1 (NRP-1)] and 2 (NRP-2) play a role in the biological behaviors of pancreatic cancer and may appear as potential therapeutic targets. The NRP family of proteins serve as co-receptors for vascular endothelial growth factor, transforming growth factor β, hepatocyte growth factor, fibroblast growth factor, semaphorin 3, epidermal growth factor, insulin-like growth factor and platelet-derived growth factor. Investigations of mechanisms that involve the NRP family of proteins may help develop novel approaches for overcoming therapy resistance in pancreatic cancer. The present review aimed to provide an in-depth exploration of the multifaceted roles of the NRP family of proteins in pancreatic cancer, including recent findings from single-cell analysis conducted within the context of pancreatic adenocarcinoma, which revealed the intricate involvement of NRP proteins at the cellular level. Through these efforts, the present study endeavored to further reveal their relationships with different biological processes and their potential as therapeutic targets in various treatment modalities, offering novel perspectives and directions for the treatment of pancreatic cancer.

Prediction and therapeutic targeting of the tumor microenvironment-associated gene CTSK in gastric cancer

BACKGROUND

Cathepsin-K (CTSK) is overexpressed in Gastric cancer (GC) and the mechanism of its overexpression in GC is still unclear. The present work found CTSK as a potential predictive biomarker and immunotherapeutic target for GC based on the tumor microenvironment (TME).

METHODS

From public databases, gene expression profiles and clinical data of GC were downloaded to analyze the distribution of stromal and immune cells and tumor abundance in TME. Differentially expressed genes (DEGs) associated with TME were obtained by differential analysis, followed by cross-screening to obtain CTSK as a gene associated with TME. Next, a series of methods and tools were employed to explore the relationships between clinicopathological features of GC and CTSK expression as well as prognosis, tumor immune microenvironment, immune checkpoints and drug sensitivity. And GSEA was used to investigate the potential role of CTSK in the tumor microenvironment of GC.

RESULTS

From the dataset, we obtained a total of 656 DEGs associated with TME and the stromal component of TME was found to be closely involved in GC prognosis. CTSK was cross-screened as the key gene associated with TME by the PPI network and univariate Cox regression analysis. Pan-cancer analysis revealed significant high expression of CTSK in a variety of cancers. Subsequently, we hypothesized that high-expressed CTSK was closely correlated with poor prognosis and lymph node metastasis of tumors, and that CTSK, a GC TME-related gene, was largely involved in a range of biological behaviors of tumors, with a significant correlation between several immune cells.

CONCLUSION

CTSK was validated as a potential prognostic biomarker related to TME of GC and could be a promising next-generation immunotherapeutic target for GC.

Structure-activity relationship studies and biological properties evaluation of peptidic NRP-1 ligands: Investigation of N-terminal cysteine importance

Neuropilin-1 (NRP-1) is a major co-receptor of vascular endothelial growth factor receptor-2 (VEGFR-2). It may also stimulate tumour growth and metastasis independently of VEGF-A165. These functions make VEGF-A165/NRP-1 complex formation and its inhibition of great interest, where NRP-1 is the target for which effective ligands are sought. Design of peptide-like inhibitors represent a strategy with great potential in the treatment of NRP-1-related disorders. Here, we present the synthesis, molecular modelling, structure-activity relationship studies as well as biological evaluation of peptides with the branched sequences H2N-X-Lys(hArg)-Dab-Oic-Arg-OH and H2N-Lys(X-hArg)-Dab-Oic-Arg-OH. Two of the designed peptides, in which Cys was inserted in X position, expressed high affinity (∼40 nM value) for NRP-1 and were resistant to enzymatic digestion in human serum. Moreover, peptide/NRP-1 complex promoted fast intracytoplasmic protein trafficking towards the plasma membrane in breast cancer cells. Our results suggest that these compounds might be good candidates for further development of VEGF-A165/NRP-1 inhibitors.

New Biosensor for Determination of Neuropilin-1 with Detection by Surface Plasmon Resonance Imaging

Neuropilin-1 is transmembrane protein with soluble isoforms. It plays a pivotal role in both physiological and pathological processes. NRP-1 is involved in the immune response, formation of neuronal circuits, angiogenesis, survival and migration of cells. The specific SPRI biosensor for the determination of neuropilin-1 was constructed using mouse monoclonal antibody that captures unbound NRP-1 form body fluids. The biosensor exhibits linearity of the analytical signal between 0.01 and 2.5 ng/mL, average precision value 4.7% and recovery between 97% and 104%. The detection limit is 0.011 ng/mL, and the limit of quantification is 0.038 ng/mL. The biosensor was validated by parallel determination of NRP-1 in serum and saliva samples using the ELISA test, with good agreement of the results.

Identification of Four New Chemical Series of Small Drug-Like Natural Products as Potential Neuropilin-1 Inhibitors by Structure-Based Virtual Screening: Pharmacophore-Based Molecular Docking and Dynamics Simulation

Neuropilin-1 (NRP-1), a surface transmembrane glycoprotein, is one of the most important co-receptors of VEGF-A165 (vascular endothelial growth factor) responsible for pathological angiogenesis. In general, NRP-1 overexpression in cancer correlates with poor prognosis and more tumor aggressiveness. NRP-1 role in cancer has been mainly explained by mediating VEGF-A165-induced effects on tumor angiogenesis. NRP-1 was recently identified as a co-receptor and an independent gateway for SARS-CoV-2 through binding subunit S2 of Spike protein in the same way as VEGF-A165. Thus, NRP-1 is of particular value as a target for cancer therapy and other angiogenesis-dependent diseases as well as for SARS-CoV-2 antiviral intervention. Herein, The Super Natural II, the largest available database of natural products (∼0.33 M), pre-filtered with drug-likeness criteria (absorption, distribution, metabolism and excretion/toxicity), was screened against NRP-1. NRP-1/VEGF-A165 interaction is one of protein-protein interfaces (PPIs) known to be challenging when approached in-silico. Thus, a PPI-suited multi-step virtual screening protocol, incorporating a derived pharmacophore with molecular docking and followed by MD (molecular dynamics) simulation, was designed. Two stages of pharmacophorically constrained molecular docking (standard and extra precisions), a mixed Torsional/Low-mode conformational search and MM-GBSA ΔG binding affinities calculation, resulted in the selection of 100 hits. These 100 hits were subjected to 20 ns MD simulation, that was extended to 100 ns for top hits (20) and followed by post-dynamics analysis (atomic ligand-protein contacts, RMSD, RMSF, MM-GBSA ΔG, Rg, SASA and H-bonds). Post-MD analysis showed that 19 small drug-like nonpeptide natural molecules, grouped in four chemical scaffolds (purine, thiazole, tetrahydropyrimidine and dihydroxyphenyl), well verified the derived pharmacophore and formed stable and compact complexes with NRP-1. The discovered molecules are promising and can serve as a base for further development of new NRP-1 inhibitors.

Scandium-44 Radiolabeled Peptide and Peptidomimetic Conjugates Targeting Neuropilin-1 Co-Receptor as Potential Tools for Cancer Diagnosis and Anti-Angiogenic Therapy

Pathological angiogenesis, resulting from an imbalance between anti- and pro-angiogenic factors, plays a pivotal role in tumor growth, development and metastasis. The inhibition of the angiogenesis process by the VEGF/VEGFR-2/NRP-1 pathway raises interest in the search for such interaction inhibitors for the purpose of the early diagnosis and treatment of angiogenesis-dependent diseases. In this work we designed and tested peptide-based radiocompounds that selectively bind to the neuropilin-1 co-receptor and prevent the formation of the pro-angiogenic VEGF-A₁₆₅/NRP-1 complex. Three biomolecules, A7R and retro-inverso ^DR7A peptides, and the branched peptidomimetic Lys(hArg)-Dab-Pro-Arg (K4R), conjugated with macrocyclic chelator through two linkers' types, were labeled with theranostic scandium-44 radionuclide, and studied in vitro as potential targeted radiopharmaceuticals. ELISA (enzyme-linked immunosorbent assay) studies showed no negative effect of the introduced biomolecules' changes and high NRP-1 affinity in the case of A7R- and K4R-radiocompounds and a lack affinity for ^DR7A-radiocompounds. All radiopeptides showed a hydrophilic nature as well as high stability against ligand exchange reactions in cysteine/histidine solutions. Unfortunately, all radiocompounds showed unsatisfactory nano-scale stability in human serum, especially for use as therapeutic radioagents. Further work is ongoing and focused on the search for angiogenesis inhibitors that are more human serum stable.

Synthesis, Physicochemical and Biological Study of Gallium-68- and Lutetium-177-Labeled VEGF-A165/NRP-1 Complex Inhibitors Based on Peptide A7R and Branched Peptidomimetic

Neuropilin-1 (NRP-1) is a surface receptor found on many types of cancer cells. The overexpression of NRP-1 and its interaction with vascular endothelial growth factor-165 (VEGF₁₆₅) are associated with tumor growth and metastasis. Therefore, compounds that block the VEGF₁₆₅/NRP-1 interaction represent a promising strategy to image and treat NRP-1-related pathologies. The aim of the presented work was to design and synthesize radioconjugates of two known peptide-type inhibitors of the VEGF₁₆₅/NRP-1 complex: A7R peptide and its shorter analog, the branched peptidomimetic Lys(hArg)-Dab-Pro-Arg. Both peptide-type inhibitors were coupled to a radionuclide chelator (DOTA) via a linker (Ahx) and so radiolabeled with Ga-68 and Lu-177 radionuclides, for diagnostic and therapeutic uses, respectively. The synthesized radioconjugates were tested for their possible use as theranostic-like radiopharmaceuticals for the imaging and therapy of cancers that overexpress NRP-1. The obtained results indicate good efficiency of the radiolabeling reaction and satisfactory stability, at least 3t_1/2 for the ⁶⁸Ga- and 1t_1/2 for the ¹⁷⁷Lu-radiocompounds, in solutions mimicking human body fluids. However, enzymatic degradation of both the studied inhibitors caused insufficient stability of the radiocompounds in human serum, indicating that further modifications are needed to sufficiently stabilize the peptidomimetics with inhibitory properties against VEGF₁₆₅/NRP-1 complex formation.

H19- and hsa-miR-338-3p-mediated NRP1 expression is an independent predictor of poor prognosis in glioblastoma

Glioblastoma multiforme (GBM) is the most common and also the most invasive brain cancer. GBM progression is rapid and its prognosis is poor. Therefore, finding molecular targets in GBM is a critical goal that could also play important roles in clinical diagnostics and treatments to improve patient prognosis. We jointly analyzed the GSE103227, GSE103229, and TCGA databases for differentially expressed RNA species, obtaining 52 long non-coding RNAs (lncRNAs), 31 microRNAs (miRNAs), and 186 mRNAs, which were used to build a competing endogenous RNA network. Kaplan–Meier and receiver operating characteristic (ROC) analyses revealed five survival-related lncRNAs: H19, LINC01574, LINC01614, RNF144A-AS1, and OSMR-AS1. With multiple optimization mRNAs, we found the H19-hsa-miR-338-3P-NRP1 regulatory pathway. Additionally, we noted high NRP1 expression in GBM patients, and Kaplan–Meier and ROC analyses showed that NRP1 expression was associated with GBM prognosis. Cox analysis indicated that NRP1 is an independent prognostic factor in GBM patients. In conclusion, H19 and hsa-miR-338-3P regulate NRP1 expression, and this pathway plays an important role in GBM.

Regulation of granulosa cell functions through NRP-1 mediated internalization of follicular fluid non-exosomal miR-210

Crosstalk between follicular fluid (FF) and granulosa cells (GCs) plays a vital role in the regulation of folliculogenesis, ensuring regular reproductive cycle in mammals. This crosstalk is primarily mediated by hormones and signaling molecules, such as cytokines and chemokines. Recently, extracellular microRNAs (miRNAs) have gained a lot of attention in cell-to-cell communication. Extracellular miRNA transportation occurs through exosomes, a kind of micro-vesicles produced from almost all cells. However, the mode of non-exosomal miRNA internalization is not much studied. In the present study, we explored the role of neuropilin-1 (NRP-1) as a receptor in internalizing FF non-exosomal miRNAs in GCs. We first confirmed the expression of NRP-1 in GCs during follicular development followed by its role in the internalization of miR-210, a non-exosomal miRNA. This study showed that incubation of GCs with a non-exosomal fraction of FF increased the content of miR-210 in GCs as compared to their control. To illustrate the role of NRP-1 as a receptor, NRP-1 was knockdown using siRNA. Silencing experimental results showed a significant decrease in uptake of miR-210 in NRP-1 knockdown GCs. Furthermore, downstream expression analysis of miR-210 target genes (CYP19A1, PCNA, and EFNA3) also confirmed the NRP-1 mediated miR-210 internalization. Results of the present study clearly demonstrated that FF non-exosomal miR-210 can be internalized through the NRP-1 receptor. Furthermore, differential expression of NRP-1 in GCs suggests its role in follicular development. Overall, these findings suggest that FF non-exosomal miRNA plays an important role in GC functions and female reproduction.

Epigenetic targeting of neuropilin-1 prevents bypass signaling in drug-resistant breast cancer

Human epidermal growth factor receptor 2 (HER2)-amplified breast cancers are treated using targeted antibodies and kinase inhibitors, but resistance to these therapies leads to systemic tumor recurrence of metastatic disease. Herein, we conducted gene expression analyses of HER2 kinase inhibitor-resistant cell lines as compared to their drug-sensitive counterparts. These data demonstrate the induction of epithelial-mesenchymal transition (EMT), which included enhanced expression of fibroblast growth factor receptor 1 (FGFR1) and axonal guidance molecules known as neuropilins (NRPs). Immunoprecipitation of FGFR1 coupled with mass spectroscopy indicated that FGFR1 forms a physical complex with NRPs, which is enhanced upon induction of EMT. Confocal imaging revealed that FGFR1 and NRP1 predominantly interact throughout the cytoplasm. Along these lines, short hairpin RNA-mediated depletion of NRP1, but not the use of NRP1-blocking antibodies, inhibited FGFR signaling and reduced tumor cell growth in vitro and in vivo. Our results further indicate that NRP1 upregulation during EMT is mediated via binding of the chromatin reader protein, bromodomain containing 4 (BRD4) in the NRP1 proximal promoter region. Pharmacological inhibition of BRD4 decreased NRP1 expression and ablated FGF-mediated tumor cell growth. Overall, our studies indicate that NRPs facilitate aberrant growth factor signaling during EMT-associated drug resistance and metastasis. Pharmacological combination of epigenetic modulators with FGFR-targeted kinase inhibitors may provide improved outcomes for breast cancer patients with drug-resistant metastatic disease.

Urea-Peptide Hybrids as VEGF-A165/NRP-1 Complex Inhibitors with Improved Receptor Affinity and Biological Properties

Neuropilin-1 (NRP-1), the major co-receptor of vascular endothelial growth factor receptor-2 (VEGFR-2), may also independently act with VEGF-A₁₆₅ to stimulate tumour growth and metastasis. Therefore, there is great interest in compounds that can block VEGF-A165/NRP-1 interaction. Peptidomimetic type inhibitors represent a promising strategy in the treatment of NRP-1-related disorders. Here, we present the synthesis, affinity, enzymatic stability, molecular modeling and in vitro binding evaluation of the branched urea–peptide hybrids, based on our previously reported Lys(hArg)-Dab-Oic-Arg active sequence, where the Lys(hArg) branching has been modified by introducing urea units to replace the peptide bond at various positions. One of the resulting hybrids increased the affinity of the compound for NRP-1 more than 10-fold, while simultaneously improving resistance for proteolytic stability in serum. In addition, ligand binding to NRP-1 induced rapid protein stock exocytotic trafficking to the plasma membrane in breast cancer cells. Examined properties characterize this compound as a good candidate for further development of VEGF₁₆₅/NRP-1 inhibitors.

A comprehensive review of tumor proliferative and suppressive role of semaphorins and therapeutic approaches

Semaphorins have been traditionally known as axon guidance proteins that negatively regulate axonal growth. However, in the past couple of decades, their versatile role in so many other biological processes has come to prominence as well. One such example is their role in cancer. In this review article, the focus was on the tumor proliferative and tumor suppressive role of all 20 semaphorin family members under the 7 semaphorin classes found in vertebrates and invertebrates as well as the ongoing and emerging therapeutic approaches to combat semaphorin-mediated cancers. Except sema6C, 19 of the 20 non-viral semaphorin family members have been discovered to be associated with cancer in one way or another. Eleven semaphorin family members have been discovered to be tumor proliferative and 8 to be tumor suppressive. Six therapeutic avenues and their safety profiles have been discussed which are currently at use or at the various stages of development. Finally, perspectives on which approach is the best for treating cancers associated with semaphorins have been given.

Clinicopathological Significance of Neuropilin 1 Expression in Gastric Cancer: A Meta-Analysis

Background

Neuropilin 1 (NRP1) is involved in tumorigenesis, development, invasion, and metastasis by promoting angiogenesis of tumors. The study is aimed at evaluating the correlation between the expression of NRP1 protein and clinicopathological features of gastric cancer by meta-analysis.

Methods

The published studies were searched in databases including CNKI, Wanfang, Chongqing VIP, Web of Science, and PubMed online. Clinical case studies were included to compare the correlation between NRP1 protein expression and clinicopathological characteristics of gastric cancer. The quality of the included literatures was evaluated by NOS scale. Meta-analysis was performed by Stata software to calculate the odds ratio (OR) and 95% confidence interval (CI).

Results

A total of 12 studies were included in this analysis, involving 1,225 patients with gastric cancer. The analysis indicated that the expression of NRP1 protein in gastric cancer tissues was lower in the group of early stage versus advanced stage (OR = 0.128, 95%CI = 0.059 − 0.277, P ≤ 0.001), tumor size less than 5 cm versus more than 5 cm (OR = 0.443, 95%CI = 0.310 − 0.632, P ≤ 0.001), TNM stage I-II group versus stage III-IV patients (OR = 0.736, 95%CI = 0.589 − 0.919, P = 0.007), well to medium differentiation group versus poor differentiation group (OR = 0.735, 95%CI = 0.632 − 0.854, P ≤ 0.001), and nonlymph node metastasis group versus lymph node metastasis group (OR = 0.667, 95%CI = 0.522 − 0.854, P ≤ 0.001). The expression of NRP1 protein in gastric cancer was not related to gender, age, and Laurèn's classification.

Conclusion

The expression of NRP1 protein in gastric cancer is closely correlated to clinical stage, tumor size, TNM stage, differentiation, and lymph node metastasis.

Preparation of truncated tissue factor antineuropilin-1 monoclonal antibody conjugate and identification of its selective thrombosis in tumor blood vessels

In recent decades, selectively inducing tumor vascular thrombosis, followed by necrosis of tumor tissues has been a promising and potential anticancer strategy. In this report, we prepared a kind of vascular targeting drug that consists of anti-neuropilin-1 monoclonal antibody (anti-NRP-1 mAb) and truncated tissue factor (tTF). Anti-NRP-1 mAb could guide tTF to the surface of tumor vascular endothelial cells and lead to subsequent vascular embolization. This vascular targeting drug, which is also one of the antibody drug conjugates, was generated using a coupling method with water-soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysulfosuccimide. Afterwards, in-vitro and in-vivo assays were performed to characterize its potential coagulation ability and antitumor activity. In-vitro experiments indicated that tTF-anti-NRP-1 monoclonal antibody (tTF-mAb) retained both the targeting activity of anti-NRP-1 mAb and the procoagulant activity of tTF. Live imaging system was used to assess its biodistribution and tumor-binding capability, which also yielded promising results. Furthermore, in-vivo studies showed that tTF-mAb was capable of significantly inducing tumor vascular thrombosis and inhibiting tumor growth in nude mice bearing subcutaneous xenografts, and histopathologic changes were rarely observed in normal organs.

Genomics Score Based on Genome-Wide Network Analysis for Prediction of Survival in Gastric Cancer: A Novel Prognostic Signature

Purpose

Gastric cancer (GC) is a product of multiple genetic abnormalities, including genetic and epigenetic modifications. This study aimed to integrate various biomolecules, such as miRNAs, mRNA, and DNA methylation, into a genome-wide network and develop a nomogram for predicting the overall survival (OS) of GC.

Materials and Methods

A total of 329 GC cases, as a training cohort with a random of 150 examples included as a validation cohort, were screened from The Cancer Genome Atlas database. A genome-wide network was constructed based on a combination of univariate Cox regression and least absolute shrinkage and selection operator analyses, and a nomogram was established to predict 1-, 3-, and 5-year OS in the training cohort. The nomogram was then assessed in terms of calibration, discrimination, and clinical usefulness in the validation cohort. Afterward, in order to confirm the superiority of the whole gene network model and further reduce the biomarkers for the improvement of clinical usefulness, we also constructed eight other models according to the different combinations of miRNAs, mRNA, and DNA methylation sites and made corresponding comparisons. Finally, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were also performed to describe the function of this genome-wide network.

Results

A multivariate analysis revealed a novel prognostic factor, a genomics score (GS) comprising seven miRNAs, eight mRNA, and 19 DNA methylation sites. In the validation cohort, comparing to patients with low GS, high-GS patients (HR, 12.886; P < 0.001) were significantly associated with increased all-cause mortality. Furthermore, after stratification of the TNM stage (I, II, III, and IV), there were significant differences revealed in the survival rates between the high-GS and low-GS groups as well (P < 0.001). The 1-, 3-, and 5-year C-index of whole genomics-based nomogram were 0.868, 0.895, and 0.928, respectively. The other models have comparable or relatively poor comprehensive performance, while they had fewer biomarkers. Besides that, DAVID 6.8 further revealed multiple molecules and pathways related to the genome-wide network, such as cytomembranes, cell cycle, and adipocytokine signaling.

Conclusion

We successfully developed a GS based on genome-wide network, which may represent a novel prognostic factor for GC. A combination of GS and TNM staging provides additional precision in stratifying patients with different OS prognoses, constituting a more comprehensive sub-typing system. This could potentially play an important role in future clinical practice.

Long non-coding RNA (lncRNA) and epithelial-mesenchymal transition (EMT) in colorectal cancer: a systematic review

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer-related death. Epithelial-mesenchymal transition (EMT) is a major process in tumor metastasis development. This systematic review aims to describe the role of long non-coding RNA (lncRNA) in EMT in CRC.

METHODS

The electronic databases, PubMed, Cochrane, and EMBASE, were searched from January1990 to June 2019 to identify studies examining lncRNA and their role in mediating EMT in CRC. Studies examining clinical specimens and/or in vitro experiments were included.

RESULTS

In 61 identified studies, 54 lncRNAs were increased in CRC compared to normal colorectal epithelium. Increased lncRNA expression was frequently associated with worse survival. Many lncRNAs mediate their effect through competitive endogenous RNA or transcription factor regulation. The ZEB1, 2/E-cadherin, Wnt/β-catenin signaling, and chromatin remodeling pathways are discussed in particular.

CONCLUSIONS

lncRNAs are major regulators of EMT and predictor adverse outcome in CRC patients. Future research must focus on delineating lncRNA function prior to potential clinical use.

Molecular insights and novel approaches for targeting tumor metastasis

In recent years, due to the effective drug delivery and preciseness of tumor sites or microenvironment, the targeted drug delivery approaches have gained ample attention for tumor metastasis therapy. The conventional treatment approaches for metastasis therapy have reported with immense adverse effects because they exhibited maximum probability of killing the carcinogenic cells along with healthy cells. The tumor vasculature, comprising of vasculogenic impressions and angiogenesis, greatly depends upon the growth and metastasis in the tumors. Therefore, various nanocarriers-based delivery approaches for targeting to tumor vasculature have been attempted as efficient and potential approaches for the treatment of tumor metastasis and the associated lesions. Furthermore, the targeted drug delivery approaches have found to be most apt way to overcome from all the limitations and adverse effects associated with the conventional therapies. In this review, various approaches for efficient targeting of pharmacologically active chemotherapeutics against tumor metastasis with the cohesive objectives of prognosis, tracking and therapy are summarized.

Recognition Sites for Cancer-targeting Drug Delivery Systems

BACKGROUND

Target-homing drug delivery systems are now gaining significant attention for use as novel therapeutic approaches in antitumor targeting for cancer therapy. Numerous targeted drug delivery systems have been designed to improve the targeting effects because these systems can display a range of favorable properties, thus, providing suitable characteristics for clinical applicability of anticancer drugs, such as increasing the solubility, and improving the drug distribution at target sites. The majority of these targeting systems are designed with respect to differences between cancerous and normal tissues, for instance, the low pH of tumor tissues or overexpressed receptors on tumor cell membranes. Due to the growing number of targeting possibilities, it is important to know the tumor-specific recognition strategies for designing novel, targeted, drug delivery systems. Herein, we identify and summarize literature pertaining to various recognition sites for optimizing the design of targeted drug delivery systems to augment current chemotherapeutic approaches.

OBJECTIVE

This review focuses on the identification of the recognition sites for developing targeted drug delivery systems for use in cancer therapeutics.

METHODS

We have reviewed and compiled cancer-specific recognition sites and their abnormal characteristics within tumor tissues (low pH, high glutathione, targetable receptors, etc.), tumor cells (receptor overexpression or tumor cell membrane changes) and tumor cell organelles (nuclear and endoplasmic reticular dysregulation) utilizing existing scientific literature. Moreover, we have highlighted the design of some targeted drug delivery systems that can be used as homing tools for these recognition sites.

RESULTS AND CONCLUSION

Targeted drug delivery systems are a promising therapeutic approach for tumor chemotherapy. Additional research focused on finding novel recognition sites, and subsequent development of targeting moieties for use with drug delivery systems will aid in the evaluation and clinical application of new and improved chemotherapeutics.

Resistance of melanoma cells to anticancer treatment: a role of vascular endothelial growth factor

Melanoma is one of the most aggressive and resistant to treatment neoplasms. There are still many challenges despite many promising advances in anticancer treatment. Currently, the main problem for all types of treatment is associated with heterogeneity. Due to heterogeneity of cancer cells, "precise" targeting of a medicine against a single phenotype limits the efficacy of treatment and affects resistance to applied therapy. Therefore it is important to understand aetiology and reasons for heterogeneity in order to develop effective and long-lasting treatment. This review summarises roles of vascular endothelial growth factor (VEGF) that may stimulate growth of a melanoma tumour irrespective of its proangiogenic effects, contributing to cancer heterogeneity. VEGF triggers processes associated with extracellular matrix remodelling, cell migration, invasion, angiogenesis, inhibition of immune responses and favours phenotypic plasticity and epithelial-mesenchymal transition. Consequently, it participates in mechanisms of interactions between melanoma cancer cells and microenvironment and it can modify sensitivity to therapeutic factors.

A new molecular probe: An NRP-1 targeting probe for the grading diagnosis of glioma in nude mice

Magnetic resonance molecular imaging, as a safe imaging technology, provides a new idea for the early qualitative and hierarchical diagnosis of gliomas. The purpose of this study was to design and evaluate the value of neuropilin-1 (NRP-1) targeting molecular probes in the hierarchical diagnosis of gliomas. First, we created an NRP-1 targeted magnetic resonance molecular probe (USPIO-PEG-tLyP-1) by combining the polypeptide tLyP-1 with ultra-small superparamagnetic iron oxide nanoparticles (USPIONs), detecting the physical properties by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Second, in vivo experiments, we established two different degrees of malignant gliomas in-situ in nude mice by injecting U87 and CHG-5 cells. Then, to detect the binding ability of the probe with different grades of tumour tissues, we injected the probe into the tumour-bearing mice through the tail vein. Next, MRI was performed before injection, and 6 h, 12 h, 24 h after injection, and we found significantly more iron particles in the tumour tissues of U87 tumour-bearing mice than in tumour tissues of CHG-5 tumour-bearing mice. The signal intensities of the T2-weighted images of the tumour tissues of each group as well as microscopic observations by Prussian blue staining indicated that the binding ability of this molecular probe to U87 glioma (HGG) with high NRP-1 expression was significantly greater than that of CHG-5 glioma (LGG) with low NRP-1 expression (P < 0.01). Therefore, this study confirms that the novel molecular probe USPIO-PEG-tLyP-1 can be used for the grading diagnosis by MRI for gliomas of high and low grade with different NRP-1 expression levels.

Functionalized Tobacco Mosaic Virus Coat Protein Monomers and Oligomers as Nanocarriers for Anti-Cancer Peptides

Components with self-assembly properties derived from plant viruses provide the opportunity to design biological nanoscaffolds for the ordered display of agents of diverse nature and with complementing functions. With the aim of designing a functionalized nanoscaffold to target cancer, the coat protein (CP) of Tobacco mosaic virus (TMV) was tested as nanocarrier for an insoluble, highly hydrophobic peptide that targets the transmembrane domain of the Neuropilin-1 (NRP1) receptor in cancer cells. The resulting construct CPL-K (CP-linker-“Kill”) binds to NRP1 in cancer cells and disrupts NRP1 complex formation with PlexA1 as well as downstream Akt survival signaling. The application of CPL-K also inhibits angiogenesis and cell migration. CP was also fused to a peptide that targets the extracellular domain of NRP1 and this fusion protein (CPL-F, CP-Linker-“Find”) is shown to bind to cultured cancer cells and to inhibit NRP1-dependent angiogenesis as well. CPL-K and CPL-F maintain their anti-angiogenic properties upon co-assembly to oligomers/nanoparticles together with CPL. The observations show that the CP of TMV can be employed to generate a functionalized nanoparticle with biological activity. Remarkably, fusion to CPL allowed us to solubilize the highly insoluble transmembrane NRP1 peptide and to retain its anti-angiogenic effect.

Synthesis, 3D-structure and stability analyses of NRPa-308, a new promising anti-cancer agent

We report herein the synthesis of a newly described anti-cancer agent, NRPa-308. This compound antagonizes Neuropilin-1, a multi-partners transmembrane receptor overexpressed in numerous tumors, and thereby validated as promising target in oncology. The preparation of NRPa-308 proved challenging because of the orthogonality of the amide and sulphonamide bonds formation. Nevertheless, we succeeded a gram scale synthesis, according to an expeditious three steps route, without intermediate purification. This latter point is of utmost interest in reducing the ecologic impact and production costs in the perspective of further scale-up processes. The purity of NRPa-308 has been attested by means of conventional structural analyses and its crystallisation allowed a structural assessment by X-Ray diffraction. We also reported the remarkable chemical stability of this molecule in acidic, neutral and basic aqueous media. Eventually, we observed for the first time the accumulation of NRPa-308 in two types of human breast cancer cells MDA-MB231 and BT549.

N-glycosylation-defective splice variants of neuropilin-1 promote metastasis by activating endosomal signals

Neuropilin-1 (NRP1) is an essential transmembrane receptor with a variety of cellular functions. Here, we identify two human NRP1 splice variants resulting from the skipping of exon 4 and 5, respectively, in colorectal cancer (CRC). Both NRP1 variants exhibit increased endocytosis/recycling activity and decreased levels of degradation, leading to accumulation on endosomes. This increased endocytic trafficking of the two NRP1 variants, upon HGF stimulation, is due to loss of N-glycosylation at the Asn150 or Asn261 site, respectively. Moreover, these NRP1 variants enhance interactions with the Met and β1-integrin receptors, resulting in Met/β1-integrin co-internalization and co-accumulation on endosomes. This provides persistent signals to activate the FAK/p130Cas pathway, thereby promoting CRC cell migration, invasion and metastasis. Blocking endocytosis or endosomal Met/β1-integrin/FAK signaling profoundly inhibits the oncogenic effects of both NRP1 variants. These findings reveal an important role for these NRP1 splice variants in the regulation of endocytic trafficking for cancer cell dissemination.

Construction and characterization of a truncated tissue factor‑coagulation‑based composite system for selective thrombosis in tumor blood vessels

The selective induction of tumor vascular thrombosis using truncated tissue factor (tTF) delivered via a target ligand is a promising novel antitumor strategy. In the present study, an anti-neuropilin-1 (NRP-1) monoclonal antibody (mAb)-streptavidin (SA):tTF-biotin (B) composite system was established. In this system, anti-NRP-1-mAb located tTF to the tumor vascular endothelial cell surface and induced vascular embolization. Due to their high binding affinity, SA and B were used to enhance thrombogenic activity. mAb was conjugated with SA using a coupling method with water-soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysulfosuccinimide. Biotinylated tTF (tTF-B) was prepared using a B-labeling kit subsequent to the generation and purification of fusion protein tTF. Confocal microscopy and flow cytometry indicated that the anti-NRP-1-mAb-SA conjugate retained mAb targeting activity. The preservation of B-conjugate binding capacity was confirmed using a competitive ELISA, and factor X-activation analysis revealed that tTF-B retained the procoagulant activity exhibited by tTF. Live imaging was performed to assess mAb-SA distribution and tumor-targeting capability, and this yielded promising results. The results of in vivo studies in mice with subcutaneous xenografts demonstrated that this composite system significantly induced tumor vascular thrombosis and inhibited tumor growth, whereas these histological changes were not observed in normal organs.

Non-viral nano-immunotherapeutics targeting tumor microenvironmental immune cells

The tumor microenvironmental immune cells (TMICs) consists of myeloid cells (tumor-associated macrophages, dendritic cells, myeloid-derived suppressor cells, etc.) and lymphocytes (T cells and B cells), all of which could be immunologically suppressed through their interactions with cancer cells. Immunological understanding of the tumor microenvironment (TME) has led to great success in the development of clinical cancer immunotherapeutic. The most advanced cancer immunotherapies are chimeric antigen receptor-modified T cells (CAR-T cells) and checkpoint inhibiting antibodies blocking CTLA4, PD-1 and PD-L1. However, many hurdles remain that should be addressed for improved therapeutic efficacy and reduced side effects such as cytokine release syndrome and patient-death. In recent decades, nanoparticles have been demonstrated as an efficient drug delivery tool due to their ease of modification, biocompatibility and intrinsic tumor targeting effect, and also been applied for cancer immunotherapy. In this review, we briefly introduce the immunosuppressive functions of TMICs and review recent advances in the development of TMIC-targeted nanotherapeutics for cancer immunotherapy. Tumor-associated macrophage (TAM)-targeted systems have shown to deplete or repolarize macrophages to M1 state for anti-tumoral immune responses. Tumor-infiltrating T cell (TIT)-targeted strategies have provided the activation of effector T cells and suppression of regulatory T cells in tumor, overcoming the current hurdles of single regimen checkpoint inhibitors. Lastly, recent studies on dendritic cell-targeted mRNA vaccination are discussed and the future perspectives of nano-immunotherapeutic for next-generation of cancer immunotherapy is emphasized.

Expression of NRP-1 and NRP-2 in Endometrial Cancer

Background: Neuropilins (NRPs) participate in many processes related to cancer development such as angiogenesis, lymphangiogenesis and metastasis. Although endometrial cancer is one of the most common gynecological cancers, it has not been studied in terms of NRPs expression.

Objective: The aim of this study was to investigate the potential utility of NRPs as important factors in the diagnosis and treatment of endometrial cancer.

Methods: Our study consisted of 45 women diagnosed with endometrial cancer at the following degrees of histological differentiation: G1, 17; G2, 15; G3, 13 cases. The control group included 15 women without neoplastic changes. The immunohistochemical reactions were evaluated using light microscopy.

Results: We did not detect the expression of NRP-1 and NRP-2 in the control group. NRP-1 expression was found exclusively in cancer cells. It was higher in G2 and G3 and reached about 190% of G1. NRP-2 expression was observed in the endothelium and was similar across all three cancer grades. In cancer cells, NRP-2 expression increased with the degree of histological differentiation.

Conclusion: NRP1 and NRP2 are candidates for complementary diagnostic molecular markers and promising new targets for molecular, personalized anticancer therapies.

iRGD: A Promising Peptide for Cancer Imaging and a Potential Therapeutic Agent for Various Cancers

Poor penetration into the tumor parenchyma and the reduced therapeutic efficacy of anticancer drugs and other medications are the major problems in tumor treatment. A new tumor-homing and penetrating peptide, iRGD (CRGDK/RGPD/EC), can be effectively used to combine and deliver imaging agents or anticancer drugs into tumors. The different “vascular zip codes” expressed in different tissues can serve as targets for docking-based (synaptic) delivery of diagnostic and therapeutic molecules. αv-Integrins are abundantly expressed in the tumor vasculature, where they are recognized by peptides containing the RGD integrin recognition motif. The iRGD peptide follows a multistep tumor-targeting process: First, it is proteolytically cleaved to generate the CRGDK fragment by binding to the surface of cells expressing αv integrins (αvβ3 and αvβ5). Then, the fragment binds to neuropilin-1 and penetrates the tumor parenchyma more deeply. Compared with conventional RGD peptides, the affinity of iRGD for αv integrins is in the mid to low nanomolar range, and the CRGDK fragment has a stronger affinity for neuropilin-1 than that for αv integrins because of the C-terminal exposure of a conditional C-end Rule (CendR) motif (R/KXXR/K), whose receptor proved to be neuropilin-1. Consequently, these advantages facilitate the transfer of CRGDK fragments from integrins to neuropilin-1 and consequently deeper penetration into the tumor. Due to its specific binding and strong affinity, the iRGD peptide can deliver imaging agents and anticancer drugs into tumors effectively and deeply, which is useful in detecting the tumor, blocking tumor growth, and inhibiting tumor metastasis. This review aims to focus on the role of iRGD in the imaging and treatment of various cancers.

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.

A Dual Targeting Dendrimer-Mediated siRNA Delivery System for Effective Gene Silencing in Cancer Therapy

Small interfering RNA (siRNA) is emerging as a novel therapeutic for treating various diseases, provided a safe and efficient delivery is available. In particular, specific delivery to target cells is critical for achieving high therapeutic efficacy while reducing toxicity. Amphiphilic dendrimers are emerging as novel promising carriers for siRNA delivery by virtue of the combined multivalent cooperativity of dendrimers with the self-assembling property of lipid vectors. Here, we report a ballistic approach for targeted siRNA delivery to cancer cells using an amphiphilic dendrimer equipped with a dual targeting peptide bearing an RGDK warhead. According to the molecular design, the amphiphilic dendrimer was expected to deliver siRNA effectively, while the aim of the targeting peptide was to home in on tumors via interaction of its warhead with integrin and the neuropilin-1 receptor on cancer cells. Coating the positively charged siRNA/dendrimer delivery complex with the negatively charged segment of the targeting peptide via electrostatic interactions led to small and stable nanoparticles which were able to protect siRNA from degradation while maintaining the accessibility of RGDK for targeting cancer cells and preserving the ability of the siRNA to escape from endosomes. The targeted system had enhanced siRNA delivery, stronger gene silencing, and more potent anticancer activity compared to nontargeted or covalent dendrimer-based systems. In addition, neither acute toxicity nor induced inflammation was observed. Consequently, this delivery system constitutes a promising nonviral vector for targeted delivery and can be further developed to provide RNAi-based personalized medicine against cancer. Our study also gives new perspectives on the use of nanotechnology based on self-assembling dendrimers in various biomedical applications.

Anti-neuropilin-1 monoclonal antibody suppresses the migration and invasion of human gastric cancer cells via Akt dephosphorylation

Neuropilin-1 (NRP-1) is involved in a range of physiological and pathological processes, including neuronal cell guidance, cardiovascular development, immunity, angiogenesis and the pathogenesis of cancer. Targeting of NRP-1 is considered to be a potential cancer therapy and a number of approaches have been investigated, including the use of small interfering RNA, peptides, soluble NRP antagonists and monoclonal antibodies. The present study used a novel anti-neuropilin-1 monoclonal antibody (anti-NRP-1 mAb) to investigate its potential anti-tumor effects on human gastric cancer cells in vitro and in vivo, as well as its underlying mechanisms of action. Using an MTT assay, it was observed that anti-NRP-1 mAb (<150 µg/ml) had no effects on the viability of gastric cancer cell line BGC-823, while a Boyden chamber assay indicated that treatment with anti-NRP-1 mAb suppressed the migration and invasion of BGC-823 cells. Western blot analysis also demonstrated that phosphorylation of Akt was reduced in BGC-823 cells treated with anti-NRP-1 mAb. Furthermore, anti-NRP-1 mAb suppressed the growth of gastric cancer xenograft tumors and downregulated the expression of vascular endothelial growth factor proteins within tumors in nude mice. These data indicate the potential effects of anti-NRP-1 mAb on malignant tumors and suggest that inhibition of NRP-1 function with anti-NRP-1 mAb may be a novel therapeutic approach in the treatment of cancer.

Peptide-Functionalized Phase-Transformation Nanoparticles for Low Intensity Focused Ultrasound-Assisted Tumor Imaging and Therapy

In this study, we successfully developed novel tumor homing-penetrating peptide-functionalized drug-loaded phase-transformation nanoparticles (tLyP-1-10-HCPT-PFP NPs) for low intensity focused ultrasound (LIFU)-assisted tumor ultrasound molecular imaging and precise therapy. With the nanoscale particle size, tLyP-1-10-HCPT-PFP NPs could pass through the tumor vascular endothelial cell gap. Induced by tLyP-1 peptide with targeting and penetrating efficiency, tLyP-1-10-HCPT-PFP NPs could increase tumor accumulation and penetrate deeply into the extravascular tumor tissue, penetrating through extracellular matrix and the cellular membrane to the cytoplasm. With LIFU assistance, tLyP-1-10-HCPT-PFP NPs could phase-transform into microbubbles and enhance tumor ultrasound molecular imaging for tumor diagnosis. Furthermore, after further irradiation by LIFU, an intracellular "explosion effect" caused by acoustic droplet vaporization, ultrasound targeted microbubble destruction, and release of 10-HCPT could realize physicochemical synergistic antitumor therapy.

Co-administration of iRGD with peptide HPRP-A1 to improve anticancer activity and membrane penetrability

To improve the specificity and penetration of anticancer peptides against tumors, in this study, we examined the effects of co-administration of the membrane-active peptide HPRP-A1 and the tumor homing/penetrating peptide iRGD. iRGD peptide is widely recognized as an efficient cell membrane penetration peptide targeting to αvβ3 integrins and neuropilin-1 (NRP-1) receptors, which show high expression in many tumor cells. The anticancer activity, cancer specificity and penetration activity in vitro and in vivo of the co-administered peptides were examined on 2D monolayer cells, 3D multi-cellular spheroids (MCS) and xenograft nude mice. Co-administration of iRGD and HPRP-A1 exhibited stronger anticancer activity and tumor specificity against A549 non-small cell lung cancer cells with NRP-1 receptor overexpression compared with HPRP-A1 alone. A549 cells showed uptake of the peptide combination and destruction of the integrity of the cell membrane, as well as adherence to the mitochondrial net, resulting in induction of apoptosis by a caspase-dependent pathway. The iRGD peptide dramatically increased the penetration depth of HPRP-A1 on A549 MCS and anticancer efficacy in an A549 xenograft mouse model. Our results suggest that the co-administration strategy of anticancer and penetrating peptides could be a potential therapeutic approach for cancer treatment in clinical practice.

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.

Role of NRP-1 in VEGF-VEGFR2-Independent Tumorigenesis

Recent studies suggest that neuropilin-1 (NRP-1) promotes angiogenesis mainly via VEGF and its receptors. It promotes tumorigenesis via formation of the NRP-1/ VEGF (vascular endothelial growth factor)/VEGFR2 (vascular endothelial growth factor receptor 2) complex. In addition to VEGF and its receptors, NRP-1 also binds with other growth factors such as platelet-derived growth factor (PDGF) and platelet-derived growth factor receptor (PDGFR). PDGF plays important roles in cellular proliferation and, in particular, blood vessel formation. Moreover, recent studies show that NRP-1 promotes angiogenesis via the NRP-1-ABL pathway, but independent of VEGF-VEGFR2. RAD51 is a protein involved in the signaling pathways of NRP1-ABL and PDGF(R), the expression of which is positively associated with cell radioresistance and chemoresistance. NRP-1 activates the signaling pathways of ABL and PDGF(R) to upregulate RAD51, which induces resistance to radiotherapy and chemotherapy in cancer cells. Furthermore, NRP-1 activates the tumor microenvironment by binding with fibronectin and activating ABL, thereby promoting tumor growth. Inhibition of NRP-1 may overcome the limitations of individually inhibiting the VEGF-VEGFR2 pathway in cancer therapy and provide new ideas for cancer treatment. Therefore, we review the role of NRP-1 in VEGF-VEGFR2-independent tumorigenesis.

Multifaceted Role of Neuropilins in the Immune System: Potential Targets for Immunotherapy

Neuropilins (NRPs) are non-tyrosine kinase cell surface glycoproteins expressed in all vertebrates and widely conserved across species. The two isoforms, such as neuropilin-1 (NRP1) and neuropilin-2 (NRP2), mainly act as coreceptors for class III Semaphorins and for members of the vascular endothelial growth factor family of molecules and are widely known for their role in a wide array of physiological processes, such as cardiovascular, neuronal development and patterning, angiogenesis, lymphangiogenesis, as well as various clinical disorders. Intriguingly, additional roles for NRPs occur with myeloid and lymphoid cells, in normal physiological as well as different pathological conditions, including cancer, immunological disorders, and bone diseases. However, little is known concerning the molecular pathways that govern these functions. In addition, NRP1 expression has been characterized in different immune cellular phenotypes including macrophages, dendritic cells, and T cell subsets, especially regulatory T cell populations. By contrast, the functions of NRP2 in immune cells are less well known. In this review, we briefly summarize the genomic organization, structure, and binding partners of the NRPs and extensively discuss the recent advances in their role and function in different immune cell subsets and their clinical implications.

p53-R273H upregulates neuropilin-2 to promote cell mobility and tumor metastasis

Mounting evidence indicates that hotspot p53 mutant proteins often possess gain-of-function property in promoting cell mobility and tumor metastasis. However, the molecular mechanisms are not totally understood. In this study, we demonstrate that the hotspot mutation, p53-R273H, promotes cell migration, invasion in vitro and tumor metastasis in vivo. p53-R273H significantly represses expression of DLX2, a homeobox protein involved in cell proliferation and pattern formation. We show that p53-R273H-mediated DLX2 repression leads to upregulation of Neuropilin-2 (NRP2), a multifunctional co-receptor involved in tumor initiation, growth, survival and metastasis. p53-R273H-induced cell mobility is effectively suppressed by DLX2 expression. Furthermore, knockdown of NRP2 significantly inhibits p53-R273H-induced tumor metastasis in xenograft mouse model. Together, these results reveal an important role for DLX2-NRP2 in p53-R273H-induced cell mobility and tumor metastasis.

Elevated expression of neuropilin-2 associated with unfavorable prognosis in hepatocellular carcinoma

Neuropilin-2 (NRP2) is a single-pass transmembrane glycoprotein and has recently been detected in several human cancer cells. However, its clinical relevance in hepatocellular carcinoma (HCC) remains unclear. This study aimed at evaluating NRP2 expression and clinicopathological significance in HCC patients. Tissue microarray of 190 HCC patients from the First Affiliated Hospital of Zhejiang University was established, and immunohistochemical staining was performed for NRP2. The Kaplan-Meier analysis and Cox proportional hazard model were used to analyze the survival rate. We found that NRP2 expression in HCC was significantly associated with tumor histological degree (P=0.023) and cirrhosis (P=0.040). Furthermore, NRP2-positive HCC patients demonstrated shorter disease-free survival (DFS) and overall survival (OS) than those of NRP2-negative patients. Then, the multivariate Cox analysis showed that hazard ratios of NRP2-positive patients with DFS and OS were 2.167 (95% CI: 1.626, 2.889) and 2.317 (95% CI: 1.548, 3.469), respectively. Our results suggested that NRP2 expression was considered as an independent factor for the prediction of unfavorable prognosis in HCC patients, and we believe that NRP2 could serve as a biomarker of poor prognosis and a novel target in treating HCC tumors.

Pilot assessment of vascular endothelial growth factor receptors and trafficking pathways in recurrent and metastatic canine subcutaneous mast cell tumours

Canine subcutaneous mast cell tumour (scMCT) shows less aggressive biological behaviour than cutaneous MCT. Vascular endothelial growth factor receptor 2 (VEGFR2) is expressed by neoplastic cells in canine scMCT, but the relevance of this signalling pathway for disease pathobiology is not clear. The objective of this study was to quantify VEGF‐A, VEGFR2, pVEGFR2, the VEGF co‐receptor Neuropilin 1 (NRP‐1) and the E3 ubiquitin protein ligase c‐Cbl in canine scMCT, and to evaluate their association with disease outcome. Immunohistochemical staining for biomarkers was quantified from 14 cases of canine scMCT using manual and computer‐assisted methods. Kaplan–Meier curves were generated for disease‐free survival (DFS) and compared using Mantel–Cox log‐rank analysis. Cases with high levels of neoplastic cell VEGFR2, pVEGFR2 or c‐CBL immunoreactivity had significantly reduced DFS. All cases displayed neoplastic cells positive for VEGF‐A, which was significantly associated with pVEGFR2 immunoreactivity. There were also significant positive correlations between VEGFR2 and pVEGFR2, and between c‐CBL and pVEGFR2 levels. This pilot study demonstrates the potential utility of these markers in a subset of scMCT in dogs.

Cytoplasmic neuropilin 2 is associated with metastasis and a poor prognosis in early tongue cancer patients

Neuropilin 2 (Nrp2) plays an important role in regulating lymphangiogenesis. Nrp2 expression in early tongue cancer was investigated to predict lymph node metastasis and the long-term prognosis. The relationships between clinicopathological variables of cT1-T2N0 tongue squamous cell carcinoma (SCC) and overexpression of Nrp2, vascular endothelial growth factor C (VEGFC), vascular endothelial growth factor receptor 3 (VEGFR3), and semaphorin 3F (Sema3F) were analyzed. Expression levels were compared using oral SCC cell lines. The Nrp2 gene was silenced to determine the impact of Nrp2. Cytoplasmic Nrp2 overexpression predicted regional metastasis with sensitivity and specificity of 90.3% and 42.1%, respectively. Cytoplasmic Nrp2 overexpression (P<0.001) and VEGFC overexpression (P=0.006) were significantly related to regional metastasis (Student t-test). However, only cytoplasmic Nrp2 overexpression was an independent prognostic factor for both disease-free survival (DFS; P=0.008) and overall survival (OS; P=0.016) (Cox regression); the risk of recurrence was 12-times higher (P=0.015) and risk of mortality was 8-times higher (P=0.016). Co-localization of Nrp2 and VEGFC was greater within the cytoplasm of aggressive cell lines (HN12 and RCa-T). Nrp2 plays a role in tumourigenesis; VEGFC supplementation cannot rescue the biological function of Nrp2 in Nrp2-depleted cell lines. Cytoplasmic Nrp2 overexpression is associated with decreased OS and DFS. Cytoplasmic Nrp2 overexpression may be a reliable diagnostic and prognostic marker for early tongue SCC.

Nanoparticles for modulating tumor microenvironment to improve drug delivery and tumor therapy

Tumor microenvironment (TME) plays a critical role in tumorigenesis, tumor invasion and metastasis. TME is composed of stroma, endothelial cells, pericytes, fibroblasts, smooth muscle cells, and immune cells, which is characterized by hypoxia, acidosis, and high interstitial fluid pressure. Due to the important role of TME, we firstly reviewed the composition of TME and discussed the impact of TME on tumor progression, drug and nanoparticle delivery. Next, we reviewed current strategies developed to modulate TME, including modulating tumor vasculature permeability, tumor associated macrophage phenotypes, tumor associated fibroblasts, tumor stroma components, tumor hypoxia, and multiple interventions simultaneously. Also, potential problems and future directions of TME modulation strategy have been discussed.