Targeting VEGF–neuropilin interactions: a promising antitumor strategy

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.

The combination of apatinib and antigen-specific DC-induced T cells exert antitumor effects by potently improving the immune microenvironment of osteosarcoma

Objective

Osteosarcoma (OS) is the most common primary bone sarcoma with a high propensity for local invasion and metastasis. Although the antitumor effect of apatinib has been well confirmed in advanced OS, the synergistic effect of apatinib and immunotherapies has not yet been elucidated.

Methods

In this study, we established tumour-bearing mice and observed tumour size with low and high doses of apatinib treatments. The expression of 17 cytokines, including vascular endothelial growth factor (VEGF), was detected by protein microarray analysis. Moreover, we designed apatinib and antigen-specific dendritic cell (DC)-T combination treatment for tumour-bearing mice. Tumour growth was detected by statistical analysis of tumour size and microvessel density (MVD) counting, the protein expression of VEGF by western blotting, the cytokines interleukin 6 (IL-6), IL-17 and interferon-gamma (IFN-γ) by enzyme-linked immunosorbent assay (ELISA), and the numbers of myeloid-derived suppressor cells (MDSCs) and tumour-infiltration macrophages (TAMs) by flow cytometry.

Results

The results showed that apatinib efficiently suppressed tumour growth, and high-dose apatinib achieved a stronger effect. The same was true for DC-T immunotherapy. However, their combination treatment revealed a better oncolytic effect. Meanwhile, apatinib or DC-T treatment inhibited the expression of VEGF and the proangiogenic mediators IL-6 and IL-17 but increased IFN-γ production. Combination therapy further reduced/increased these effects. In addition, the combination treatment reduced MDSC but enhanced TAM-M1 ratios in the OS microenvironment. These findings indicated that apatinib and antigen-specific DC-T combination therapy was more efficient in oncolysis by regulating pro-/anti-angiogenic inducers and improving the immune state in the OS microenvironment.

Conclusion

This study proved that it was feasible to employ immunotherapy with therapeutic agents in OS treatment, which may provide a new approach in addition to the combination of surgery with chemotherapy in tumour treatment.

Peptidomimetic inhibitors of the VEGF-A165/NRP-1 complex obtained by modification of the C-terminal arginine

Inhibitors of the interaction between Neuropilin-1 (NRP-1) and Vascular Endothelial Growth Factor-A165 (VEGF-A165) hold significant promise as therapeutic and diagnostic agents directed against cancers overexpressing NRP-1. In our efforts in this field, a few series of strong and fairly stable peptide-like inhibitors of the general formula Lys(Har)1-Xaa2-Xaa3-Arg4 have been previously discovered. In the current work, we focused on Lys(Har)-Dap/Dab-Pro-Arg sequence. The aim was to examine whether replacing C-terminal Arg with its homologs and mimetics would yield more stable yet still potent inhibitors. Upon considering the results of modelling and other factors, ten novel analogues with Xaa4 = homoarginine (Har), 2-amino-4-guanidino-butyric acid (Agb), 2-amino-3-guanidino-propionic acid (Agp), citrulline (Cit), 4-aminomethyl-phenylalanine [Phe(4-CH2-NH2)] were designed, synthesized and evaluated. Two of the proposed modifications resulted in inhibitors with activity slightly lower [e.g. IC50 = 14.3 μM for Lys(Har)-Dab-Pro-Har and IC50 = 19.8 μM for Lys(Har)-Dab-Pro-Phe(4-CH2-NH2)] than the parent compounds [e.g. IC50 = 4.7 μM for Lys(Har)-Dab-Pro-Arg]. What was a surprise to us, the proteolytic stability depended more on position two of the sequence than on position four. The Dab2-analogues exhibited half-life times beyond 60 h. Our results build up the knowledge on the structural requirements that effective VEGF-A165/NRP-1 inhibitors should fulfil.

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.

Angiogenic activity of mitochondria; beyond the sole bioenergetic organelle

Angiogenesis is a complex process that involves the expansion of the pre-existing vascular plexus to enhance oxygen and nutrient delivery and is stimulated by various factors, including hypoxia. Since the process of angiogenesis requires a lot of energy, mitochondria play an important role in regulating and promoting this phenomenon. Besides their roles as an oxidative metabolism base, mitochondria are potential bioenergetics organelles to maintain cellular homeostasis via sensing alteration in oxygen levels. Under hypoxic conditions, mitochondria can regulate angiogenesis through different factors. It has been indicated that unidirectional and bidirectional exchange of mitochondria or their related byproducts between the cells is orchestrated via different intercellular mechanisms such as tunneling nanotubes, extracellular vesicles, and gap junctions to maintain the cell homeostasis. Even though, the transfer of mitochondria is one possible mechanism by which cells can promote and regulate the process of angiogenesis under reperfusion/ischemia injury. Despite the existence of a close relationship between mitochondrial donation and angiogenic response in different cell types, the precise molecular mechanisms associated with this phenomenon remain unclear. Here, we aimed to highlight the possible role of mitochondria concerning angiogenesis, especially the role of mitochondrial transport and the possible relation of this transfer with autophagy, the housekeeping phenomenon of cells, and angiogenesis.

Chirality and Rigidity in Triazole-Modified Peptidomimetics Interacting with Neuropilin-1

The interaction of Neuropilin-1 (NRP-1) with vascular endothelial growth factor (VEGF) has been shown to promote angiogenesis under physiological and pathological conditions. Angiogenesis around tumors is a major factor allowing for their growth and spread. Disrupting NRP-1/VEGF complex formation is thus a promising pathway for the development of new anticancer pharmaceuticals. A large body of work has been produced in the last two decades detailing the development of inhibitors of NRP-1/VEGF complex formation. Among those were peptide A7R and its smaller derivatives KXXR and K(Har)XXR. It has been previously reported that replacement of the XX backbone with triazole residues has a positive effect on the proteolytic stability of inhibitors. It has also been reported that a higher dihedral angle range restriction of the XX backbone has a positive effect on the activity of inhibitors. In this work, we have designed new triazole derivatives of K(Har)XXR inhibitors with substitution allowing for higher range restriction of the XX backbone. The obtained peptidomimetics have greater activity than their less restricted counterparts. One of the newly obtained structures has greater affinity than the reference peptide A7R.

Expression of immune regulatory factors, chemokines and growth factors in differentiated gastric cancer cells treated with an anticancer bioactive peptide combined with oxaliplatin

Gastric cancer is one of the most common malignant tumors of the digestive system. An anticancer bioactive peptide (ACBP) was previously shown to have an important role in inhibiting the differentiation of the MKN-45, N87 and GES-1 cell lines. However, to date, research on the effects of inflammatory factors in MKN-45, N87 and GES-1 cell lines after treatment with ACBP combined with oxaliplatin (OXA) has not been performed. To investigate the expression of immune regulatory factors, tumor growth factors and chemotactic factors in differentiated gastric cancer cells treated with ACBP combined with OXA, the expression of cytokines, including interleukin (IL)-1β, IL-1 receptor antagonist, IL-2, IL-4, IL-6-10, IL-12, IL-13, IL-15, IL-17, Eotaxin, basic fibroblast growth factor (bFGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-γ, monocyte chemoattractant protein (MCP)-1, IFN-γ-induced protein-10, macrophage inflammatory protein (MIP)-1α, platelet-derived growth factor (PDGF)-BB, MIP-1β, regulated upon activation, normal T cell expressed and presumably secreted, TNF-α and VEGF, was assessed with cell experiments using the Bio-Plex ProT Human Cytokine 27-plex Assay. The results indicated that immune regulatory factor, tumor growth factor and chemotactic factor expression levels were different after treatment with ACBP alone or ACBP combined with OXA. IFN-γ, IL-1β, IL-17, IL-9, IL-10, IL-15, bFGF, GM-CSF and PDGF-BB expression was decreased in MKN-45 and N87 cells after ACBP treatment (P<0.01) and ACBP+OXA treatment (P<0.01) compared with the control cells, which indicated that ACBP inhibited tumor growth by regulating these cytokines, and the combination treatment inhibited tumor growth by regulating these cytokines. MIP-1β, MCP-1 and IL-13 expression was decreased in MKN-45 and N87 cells after the combination treatment compared with ACBP treatment alone, which indicated that ACBP combined with OXA was able to inhibit tumor growth by regulating these cytokines, while the mechanism of action of the ACBP and OXA is actually different, e.g. for OXA, this would be to cause DNA damage response. Therefore, the ACBP and OXA combination treatment may be closely associated with tumor progression and metastasis with immunological competence by MCP-1, MIP-1β and IL-13 expression.

VEGF/Nrp1/HIF-1α promotes proliferation of hepatocellular carcinoma through a positive feedback loop

To investigate the role of neuropilin1 (Nrp1) in glucose metabolism and proliferation of hepatocellular carcinoma (HCC) cells and to analyze its mechanism of action. The CRISPR gene knockout technique was used to knock out the Nrp1 gene in two HCC cell lines. The effect of Nrp1 on the proliferation of HCC cells was assessed in the CCK8 assay and plate cloning assay. The expression levels of glucose consumption, lactate production, and essential proteins of the glycolytic pathway were detected to explore the effect of Nrp1 on glucose metabolism in HCC cells. Using CoCl2 to revert the expression of hypoxia inducible factor-1α (HIF-1α), the role of HIF-1α in the pro-HCC cell metabolism of Nrp1 were demonstrated. The protein synthesis inhibitor CHX and proteasome inhibitor MG-132 was used to analyze the molecular mechanism of action of Nrp1 on HIF-1α. The Kaplan-Meier method was used to calculate survival rates and plot survival curves. Based on the CCK8 assay and plate cloning assay, we found that Nrp1 knockout significantly inhibited the proliferation of HCC cells. Nrp1 inhibitor suppressed lactate production and glucose consumption in HCC cells. Knockout of Nrp1 decreased the expression of glycolytic pathway-related proteins and HIF-1α protein. Furthermore, by joint use of CoCl2 and NRP1 knockout, we confirmed that reverting HIF-1α expression could reverse the effect of Nrp1 knockout on HCC cell metabolism in vitro. Mechanistically, Nrp1 showed a close correlation with the stability of HIF-1α protein in protein stability assay. Finally, we revealed that high expression of Nrp1 in HCC tissues was associated with poor overall survival and disease-free survival of the patients. Nrp1 accelerates glycolysis and promotes proliferation of HCC by regulating HIF-1α protein stability and through the VEGF/Nrp1/HIF-1α positive feedback loop.

Vascular Endothelial Growth Factor-D (VEGF-D): An Angiogenesis Bypass in Malignant Tumors

Vascular endothelial growth factors (VEGFs) are the key regulators of vasculogenesis in normal and oncological development. VEGF-A is the most studied angiogenic factor secreted by malignant tumor cells under hypoxic and inflammatory stress, which made VEGF-A a rational target for anticancer therapy. However, inhibition of VEGF-A by monoclonal antibody drugs led to the upregulation of VEGF-D. VEGF-D was primarily described as a lymphangiogenic factor; however, VEGF-D's blood angiogenic potential comparable to VEGF-A has already been demonstrated in glioblastoma and colorectal carcinoma. These findings suggested a role for VEGF-D in facilitating malignant tumor growth by bypassing the anti-VEGF-A antiangiogenic therapy. Owing to its high mitogenic ability, higher affinity for VEGFR-2, and higher expression in cancer, VEGF-D might even be a stronger angiogenic driver and, hence, a better therapeutic target than VEGF-A. In this review, we summarized the angiogenic role of VEGF-D in blood vasculogenesis and its targetability as an antiangiogenic therapy in cancer.

Study of the skin-penetration promoting effect and mechanism of combined system of curcumin liposomes prepared by microfluidic chip and skin penetrating peptides TD-1 for topical treatment of primary melanoma

The transdermal drug delivery system (TDDS) is an effective strategy for the treatment of melanoma with fewer side effects and good biocompatible, but the skin penetration of drugs should be further promoted. Here, we proposed a new system that combined curcumin liposomes (Cur-Lips) with skin-penetrating peptides to promote skin penetration ability. However, the preparation of Cur-Lips has drawbacks of instability and low entrapment efficiency by the traditional methods. We thus innovatively designed and applied a microfluidic chip to optimize the preparation of Cur-Lips. Cur-Lips exhibited a particle size of 106.22 ± 4.94 nm with a low polydispersity index (＜0.3) and high entrapment efficiency of 99.33 ± 1.05 %, which were prepared by the microfluidic chip. The Cur-Lips increased the skin penetration capability of Cur by 2.76 times compared to its solution in vitro skin penetration experiment. With the help of skin-penetrating peptide TD-1, the combined system further promoted the skin penetration capability by 4.48 times. The (TD-1 + Cur-Lips) system also exhibited a superior inhibition effect of the tumor to B16F10 in vitro. Furthermore, the topical application of (TD-1 + Cur-Lips) gel suppressed melanoma growth in vivo, and induced tumor cell apoptosis in tumor tissues. The skin-penetration promotion mechanism of the system was investigated. It was proved that the system could interact with the lipids and keratin on the stratum corneum to promote the Cur distribute into the stratum corneum through hair follicles and sweat glands. We proved that the microfluidic chips had unique advantages for the preparation of liposomes. The innovative combined system of liposomes and biological transdermal enhancers can effectively promote the skin penetration effect of drugs and have great potential for the prevention and treatment of melanoma.

Discovery and Characteristics of a Novel Antitumor Cyclopeptide Derived from Shark

Peptides pose a challenge in drug development due to their short half-lives in vivo. In this study, we conducted in vitro degradation experiments on SAIF, which is a shark-derived peptide that we previously studied. The degradation fragments were sequenced and a truncated peptide sequence was identified. The truncated peptide was then cloned and expressed via the E. coli system with traceless cloning to form a novel cyclic peptide in vitro oxidation condition via the formation of a disulfide bond between the N- and C-termini, which was named ctSAIF. ctSAIF exhibited high anti-HCC activity and enhanced enzymatic stability in vitro, and retained antitumor activity and good biocompatibility in systemic circulation in a HCC xenograft model. Our study discovered and characterized a novel shark-derived cyclic peptide with antitumor activity, laying a foundation for its further development as an antitumor drug candidate. The study also provided a new solution for peptide drug development.

Scandium-44: Diagnostic Feasibility in Tumor-Related Angiogenesis

Angiogenesis-related cell-surface molecules, including integrins, aminopeptidase N, vascular endothelial growth factor, and gastrin-releasing peptide receptor (GRPR), play a crucial role in tumour formation. Radiolabelled imaging probes targeting angiogenic biomarkers serve as valuable vectors in tumour identification. Nowadays, there is a growing interest in novel radionuclides other than gallium-68 (⁶⁸Ga) or copper-64 (⁶⁴Cu) to establish selective radiotracers for the imaging of tumour-associated neo-angiogenesis. Given its ideal decay characteristics (E_β⁺_average: 632 KeV) and a half-life (T_1/2 = 3.97 h) that is well matched to the pharmacokinetic profile of small molecules targeting angiogenesis, scandium-44 (⁴⁴Sc) has gained meaningful attention as a promising radiometal for positron emission tomography (PET) imaging. More recently, intensive research has been centered around the investigation of ⁴⁴Sc-labelled angiogenesis-directed radiopharmaceuticals. Previous studies dealt with the evaluation of ⁴⁴Sc-appended a_vb₃ integrin-affine Arg-Gly-Asp (RGD) tripeptides, GRPR-selective aminobenzoyl-bombesin analogue (AMBA), and hypoxia-associated nitroimidazole derivatives in the identification of various cancers using experimental tumour models. Given the tumour-related hypoxia- and angiogenesis-targeting capability of these PET probes, ⁴⁴Sc seems to be a strong competitor of the currently used positron emitters in radiotracer development. In this review, we summarize the preliminary preclinical achievements with ⁴⁴Sc-labelled angiogenesis-specific molecular probes.

NRP1 contributes to stemness and potentiates radioresistance via WTAP-mediated m6A methylation of Bcl-2 mRNA in breast cancer

NRP1 is a transmembrane glycoprotein that is highly expressed in a variety of tumors. There is evidence that NRP1 can enhance the stem cell properties of tumor cells, which are thought to be resistant to radiotherapy. This study aims to elucidate the potential mechanism of NRP1 in radiation resistance. We transfected NRP1 siRNA and plasmid in breast cancer cells to detect the expression of cancer stem cell markers by western blot and qRT-PCR. The effect of NRP1 on radiotherapy resistance was assesses by immunofluorescence and flow cytometry. In vivo, we established xenograft tumor model treating with shRNA-NRP1 to assess radiotherapy sensitivity. We found that NRP1 could enhance the stem cell properties and confer radioresistance of breast cancer cells. Mechanistically, we proved that NRP1 reduced IR-induced apoptosis by downregulation of Bcl-2 via methyltransferase WTAP in m6A-depentent way. It is suggested that these molecules may be the therapeutic targets for improving the efficacy of radiotherapy for breast cancer.

Polypharmacological Cell-Penetrating Peptides from Venomous Marine Animals Based on Immunomodulating, Antimicrobial, and Anticancer Properties

Complex pathological diseases, such as cancer, infection, and Alzheimer's, need to be targeted by multipronged curative. Various omics technologies, with a high rate of data generation, demand artificial intelligence to translate these data into druggable targets. In this study, 82 marine venomous animal species were retrieved, and 3505 cryptic cell-penetrating peptides (CPPs) were identified in their toxins. A total of 279 safe peptides were further analyzed for antimicrobial, anticancer, and immunomodulatory characteristics. Protease-resistant CPPs with endosomal-escape ability in Hydrophis hardwickii, nuclear-localizing peptides in Scorpaena plumieri, and mitochondrial-targeting peptides from Synanceia horrida were suitable for compartmental drug delivery. A broad-spectrum S. horrida-derived antimicrobial peptide with a high binding-affinity to bacterial membranes was an antigen-presenting cell (APC) stimulator that primes cytokine release and naïve T-cell maturation simultaneously. While antibiofilm and wound-healing peptides were detected in Synanceia verrucosa, APC epitopes as universal adjuvants for antiviral vaccination were in Pterois volitans and Conus monile. Conus pennaceus-derived anticancer peptides showed antiangiogenic and IL-2-inducing properties with moderate BBB-permeation and were defined to be a tumor-homing peptide (THP) with the ability to inhibit programmed death ligand-1 (PDL-1). Isoforms of RGD-containing peptides with innate antiangiogenic characteristics were in Conus tessulatus for tumor targeting. Inhibitors of neuropilin-1 in C. pennaceus are proposed for imaging probes or therapeutic delivery. A Conus betulinus cryptic peptide, with BBB-permeation, mitochondrial-targeting, and antioxidant capacity, was a stimulator of anti-inflammatory cytokines and non-inducer of proinflammation proposed for Alzheimer's. Conclusively, we have considered the dynamic interaction of cells, their microenvironment, and proportional-orchestrating-host- immune pathways by multi-target-directed CPPs resembling single-molecule polypharmacology. This strategy might fill the therapeutic gap in complex resistant disorders and increase the candidates' clinical-translation chance.

A Whole New Comprehension about ncRNA-Encoded Peptides/Proteins in Cancers

Simple Summary

The advent of bioinformatics and high-throughput sequencing have disclosed the complexity of ORFs in ncRNAs. Thus, there is a dire need to deep into the real role of ncRNA-encoded proteins/peptides. Considerable progress has been achieved in several fields, ranging from the mechanism translation of ORFs in ncRNAs to various reliable detection means and experimental approaches. Several studies have been stressing functions and mechanisms of ncRNA-encoded peptides/proteins in cancers, which are helpful for us to understand the specific biological regulating procedure. Innovative research on animal models confirms the potential of clinical applications, such as being tumor biomarkers, antitumor drugs and cancer vaccines. In this review, we conclude the latest discoveries of ncRNA-encoded peptides/proteins, we are looking forwards to accelerating the pace of detection and diagnosis development in cancers.

Abstract

It is generally considered that non-coding RNAs do not encode proteins; however, more recently, studies have shown that lncRNAs and circRNAs have ORFs which are regions that code for peptides/protein. On account of the lack of 5′cap structure, translation of circRNAs is driven by IRESs, m6A modification or through rolling amplification. An increasing body of evidence have revealed different functions and mechanisms of ncRNA-encoded peptides/proteins in cancers, including regulation of signal transduction (Wnt/β-catenin signaling, AKT-related signaling, MAPK signaling and other signaling), cellular metabolism (Glucose metabolism and Lipid metabolism), protein stability, transcriptional regulation, posttranscriptional regulation (regulation of RNA stability, mRNA splicing and translation initiation). In addition, we conclude the existing detection technologies and the potential of clinical applications in cancer therapy.

Neuropilin (NRPs) Related Pathological Conditions and Their Modulators

Neuropilin 1 (NRP1) represents one of the two homologous neuropilins (NRP, splice variants of neuropilin 2 are the other) found in all vertebrates. It forms a transmembrane glycoprotein distributed in many human body tissues as a (co)receptor for a variety of different ligands. In addition to its physiological role, it is also associated with various pathological conditions. Recently, NRP1 has been discovered as a coreceptor for the SARS-CoV-2 viral entry, along with ACE2, and has thus become one of the COVID-19 research foci. However, in addition to COVID-19, the current review also summarises its other pathological roles and its involvement in clinical diseases like cancer and neuropathic pain. We also discuss the diversity of native NRP ligands and perform a joint analysis. Last but not least, we review the therapeutic roles of NRP1 and introduce a series of NRP1 modulators, which are typical peptidomimetics or other small molecule antagonists, to provide the medicinal chemistry community with a state-of-the-art overview of neuropilin modulator design and NRP1 druggability assessment.

The impact of sensory neuropathy and inflammation on epithelial wound healing in diabetic corneas

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes, with several underlying pathophysiological mechanisms, some of which are still uncertain. The cornea is an avascular tissue and sensitive to hyperglycemia, resulting in several diabetic corneal complications including delayed epithelial wound healing, recurrent erosions, neuropathy, loss of sensitivity, and tear film changes. The manifestation of DPN in the cornea is referred to as diabetic neurotrophic keratopathy (DNK). Recent studies have revealed that disturbed epithelial-neural-immune cell interactions are a major cause of DNK. The epithelium is supplied by a dense network of sensory nerve endings and dendritic cell processes, and it secretes growth/neurotrophic factors and cytokines to nourish these neighboring cells. In turn, sensory nerve endings release neuropeptides to suppress inflammation and promote epithelial wound healing, while resident immune cells provide neurotrophic and growth factors to support neuronal and epithelial cells, respectively. Diabetes greatly perturbs these interdependencies, resulting in suppressed epithelial proliferation, sensory neuropathy, and a decreased density of dendritic cells. Clinically, this results in a markedly delayed wound healing and impaired sensory nerve regeneration in response to insult and injury. Current treatments for DPN and DNK largely focus on managing the severe complications of the disease. Cell-based therapies hold promise for providing more effective treatment for diabetic keratopathy and corneal ulcers.

Efficacy of the Low Dose Apatinib plus Chemotherapy on Advanced Gastric Carcinoma

Objective

To evaluate the efficacy of low dose apatinib plus chemotherapy on advanced gastric carcinoma.

Methods

Eligible 50 patients with advanced gastric carcinoma admitted to the hospital from January 2019 to March 2020 were enrolled, and they were assigned into the control group (n = 25, chemotherapy) and observation group (apatinib plus chemotherapy). Changes of CEA, CA72-4, and VEGF levels were measured, and the efficacy of the two groups was evaluated by referring to KPS and RECIST.

Results

Significant reduction was observed in CEA, CA72-4, and VEGF in both groups, and the treatment in the observation group resulted in a greater reduction (all P < 0.05). The observation group obtained significantly higher KPS scores of compared with the control group (P < 0.05). In addition, the treatment in the observation group led to a better control rate in relative to the control group according to RECIST the score (P < 0.05).

Conclusion

The combination of low dose apatinib and chemotherapy might be a promising option for advanced gastric cancer and it merits clinical application.

Polysialic Acid in the Immune System

Polysialic acid (polySia) is a highly regulated polymer of sialic acid (Sia) with such potent biophysical characteristics that when expressed drastically influences the interaction properties of cells. Although much of what is known of polySia in mammals has been elucidated from the study of its role in the central nervous system (CNS), polySia is also expressed in other tissues, including the immune system where it presents dynamic changes during differentiation, maturation, and activation of different types of immune cells of the innate and adaptive response, being involved in key regulatory mechanisms. At least six polySia protein carriers (CCR7, ESL-1, NCAM, NRP2, ST8Sia 2, and ST8Sia 4) are expressed in different types of immune cells, but there is still much to be explored in regard not only to the regulatory mechanisms that determine their expression and the structure of polySia chains but also to the identification of the cis- and trans- ligands of polySia that establish signaling networks. This review summarizes the current knowledge on polySia in the immune system, addressing its biosynthesis, its tools for identification and structural characterization, and its functional roles and therapeutic implications.

An Update on the Roles of circRNA-ZFR in Human Malignant Tumors

CircRNAs (circular RNAs) are single-stranded RNAs that form covalently closed loops and function as important regulatory elements of the genome through multiple mechanisms. Increasing evidence had indicated that circRNAs, which might serve as either oncogenes or tumor suppressors, played vital roles in the pathophysiology of human diseases, especially in tumorigenesis and progression. CircRNA-ZFR (circular RNA zinc finger RNA binding protein) is a circular RNA that had attracted much attention in recent years. It has been found that circRNA-ZFR was abnormally expressed in a variety of malignant tumors, and its dysregulated expression was closely related to tumor stage, cancer metastasis and patients’ prognosis. Recent studies had shown that aberrantly expressed circRNA-ZFR could regulate the malignant biological behaviors of tumors through various mechanisms; further exploration of circRNA-ZFR expression in tumors and its regulation on malignant biological behaviors such as tumor proliferation, invasion and drug resistance will provide new ideas for clinical tumors diagnosis and treatment.

Novel Small-Molecule Inhibitors of the SARS-CoV-2 Spike Protein Binding to Neuropilin 1

Furin cleavage of the SARS-CoV-2 spike protein results in a polybasic terminal sequence termed the C-end rule (CendR), which is responsible for the binding to neuropilin 1 (NRP1), enhancing viral infectivity and entry into the cell. Here we report the identification of 20 small-molecule inhibitors that emerged from a virtual screening of nearly 950,000 drug-like compounds that bind with high probability to the CendR-binding pocket of NRP1. In a spike NRP1 binding assay, two of these compounds displayed a stronger inhibition of spike protein binding to NRP1 than the known NRP1 antagonist EG00229, for which the inhibition of the CendR peptide binding to NRP1 was also experimentally confirmed. These compounds present a good starting point for the design of small-molecule antagonists against the SARS-CoV-2 viral entry.

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.

CAF promotes chemoresistance through NRP2 in gastric cancer

BACKGROUND

Fibroblasts are the predominant cell type in the stroma of tumor, and cancer-associated fibroblasts (CAFs) promote cancer chemoresistance by secreting various bioactive molecules. However, the differential expression between CAFs and normal fibroblasts (NFs) and how can CAFs uniquely impact cancer cells are still unexplored.

METHODS

Primary CAFs and NFs were cultured from gastric cancer specimens, and their variant expression was analyzed by RNA-sequencing. Chemoresistance was evaluated by measuring cell viability, apoptosis, and 3D-coculture techniques.

RESULTS

CAFs were isolated from gastric cancers and defined by specific cell-surface markers. CAFs decreased the sensitivity of gastric cancer cells to 5-FU. RNA-sequencing showed that CAFs expressed a higher level of NRP2 than NFs. And the high expression of NRP2 was correlated with worse oncological outcomes in gastric cancer patients. Further study showed that the knockdown of NRP2 eradicated the resistance to 5-FU. And the secretion of stromal cell-derived factor-1 (SDF-1) was reduced following NRP2 knockdown. Furthermore, we found that the increased sensitivity to 5-FU was induced by DNA damage. And this process was mediated by predominant effectors of the Hippo pathway, YAP/TAZ.

CONCLUSIONS

The present study indicated that CAFs within gastric cancers promote chemoresistance through the expression of NRP2. The secretion of SDF-1 that mediated by VEGF/NRP2 signaling in CAFs and the activation of Hippo pathway in cancer cells in large part participated in this project.

Characterization of peptide binding to the SARS-CoV-2 host factor neuropilin

The ongoing coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a global health concern. It is now well established that the spike (S) protein of SARS-CoV-2 interacts with its primary host receptor, the angiotensin converting enzyme 2 (ACE2). Additionally, the interaction of S with the neuropilin (NRP) receptor has been reported to facilitate viral entry. SARS-CoV-2 S protein binds to neuropilin-1 (NRP1) by virtue of a CendR motif which terminates with either an arginine or lysine. Furthermore, a number of different peptide sequences have been reported to bind to the same site in NRP1 including vascular endothelial growth factor A and other viral proteins. To gain a deeper understanding of additional factors besides the C-terminal arginine that may favour high NRP1 binding, several modelled peptides were investigated using triplicate 1 μs molecular dynamics simulations. A C-end histidine failed to exhibit strong NRP1 affinity. Some previously reported factors that increase binding affinity and secure NRP1 receptor activation was observed in the NRP1-peptide complexes studied and such complexes had higher molecular mechanics-generalized Born surface area based free energy of binding. Additionally, the results also highlight the relevance of an exposed arginine at its canonical location as capping it blocked arginine from engaging key residues at the NRP1 receptor site that are indispensable for functional binding; and that the presence of proline reinforces the C-terminal arginine. Given that stable NRP1 binding is crucial for viral uptake, stable interactions should be accounted for in the design of potential drugs and treatment routes to target or disrupt this interface, considering the S1-NRP1 interaction as well as its endogenous VEGF-A ligand that is associated with nociception.

Combination of cell-penetrating peptides with nanomaterials for the potential therapeutics of central nervous system disorders: a review

Although nanomedicine have greatly developed and human life span has been extended, we have witnessed the soared incidence of central nervous system (CNS) diseases including neurodegenerative diseases (Alzheimer's disease, Parkinson's disease), ischemic stroke, and brain tumors, which have severely damaged the quality of life and greatly increased the economic and social burdens. Moreover, partial small molecule drugs and almost all large molecule drugs (such as recombinant protein, therapeutic antibody, and nucleic acid) cannot cross the blood-brain barrier. Therefore, it is especially important to develop a drug delivery system that can effectively deliver therapeutic drugs to the central nervous system for the treatment of central nervous system diseases. Cell penetrating peptides (CPPs) provide a potential strategy for the transport of macromolecules through the blood-brain barrier. This study analyzed and summarized the progress of CPPs in CNS diseases from three aspects: CPPs, the conjugates of CPPs and drug, and CPPs modified nanoparticles to provide scientific basis for the application of CPPs for CNS diseases.

The Role of VEGF Receptors as Molecular Target in Nuclear Medicine for Cancer Diagnosis and Combination Therapy

Simple Summary

The rapid development of diagnostic and therapeutic methods of the cancer treatment causes that these diseases are becoming better known and the fight against them is more and more effective. Substantial contribution in this development has nuclear medicine that enables very early cancer diagnosis and early start of the so-called targeted therapy. This therapeutic concept compared to the currently used chemotherapy, causes much fewer undesirable side effects, due to targeting a specific lesion in the body. This review article discusses the possible applications of radionuclide-labelled tracers (peptides, antibodies or synthetic organic molecules) that can visualise cancer cells through pathological blood vessel system in close tumour microenvironment. Hence, at a very early step of oncological disease, targeted therapy can involve in tumour formation and growth.

Abstract

One approach to anticancer treatment is targeted anti-angiogenic therapy (AAT) based on prevention of blood vessel formation around the developing cancer cells. It is known that vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptors (VEGFRs) play a pivotal role in angiogenesis process; hence, application of angiogenesis inhibitors can be an effective approach in anticancer combination therapeutic strategies. Currently, several types of molecules have been utilised in targeted VEGF/VEGFR anticancer therapy, including human VEGF ligands themselves and their derivatives, anti-VEGF or anti-VEGFR monoclonal antibodies, VEGF binding peptides and small molecular inhibitors of VEGFR tyrosine kinases. These molecules labelled with diagnostic or therapeutic radionuclides can become, respectively, diagnostic or therapeutic receptor radiopharmaceuticals. In targeted anti-angiogenic therapy, diagnostic radioagents play a unique role, allowing the determination of the emerging tumour, to monitor the course of treatment, to predict the treatment outcomes and, first of all, to refer patients for AAT. This review provides an overview of design, synthesis and study of radiolabelled VEGF/VEGFR targeting and imaging agents to date. Additionally, we will briefly discuss their physicochemical properties and possible application in combination targeted radionuclide tumour therapy.

Effect of luteolin on apoptosis and vascular endothelial growth factor in human choroidal melanoma cells

AIM

To investigate the effects of luteolin on apoptosis, the cell cycle, and the expression and secretion of vascular endothelial growth factor (VEGF) in human choroidal melanoma cells (C918 and OCM-1).

METHODS

C918 and OCM-1 cells cultured in vitro were treated with various concentrations of luteolin (0, 5, 10, 15 µmol/L). Cell growth was observed with an inverted microscope, and cell cycle arrest was detected by propidium iodide (PI) staining using flow cytometry. Apoptosis was detected by Hoechst33342 staining, and apoptosis rate was determined by Annexin V-FITC/PI experiments using flow cytometry. The expression of apoptosis-related proteins Bcl-2, Bax and VEGF was analyzed using Western blots. The levels of VEGF secreted by the cells into the supernatant was analyzed using ELISA.

RESULTS

After treating with 5 to 15 µmol/L luteolin for 48h, the fusion degree of C918 and OCM-1 cells decreased, and more floating apoptotic cells appeared. Luteolin treatment increased the G0-G1 phase ratio of the C918 and OCM-1 cells, blocked cell cycle progression, and increased the apoptosis rate of the C918 and OCM-1 cells. Western blot showed that luteolin decreased the expression of Bcl-2 and VEGF in the C918 and OCM-1 cells and increased the expression of Bax protein. The ELISA results showed that 10 to 15 µmol/L luteolin decreased the cell secretion of VEGF.

CONCLUSION

Luteolin may induce apoptosis by regulating the levels of apoptosis-related proteins in C918 and OCM-1 cells. Luteolin can induce cell cycle arrest, decrease the expression of VEGF.

Grading Evolution and Contemporary Prognostic Biomarkers of Clinically Significant Prostate Cancer

Simple Summary

Prostate cancer treatment decisions are based on clinical stage and histological diagnosis, including Gleason grading assessed by a pathologist, in biopsies. Prior to staging and grading, serum or blood prostate-specific antigen (PSA) levels are measured and often trigger diagnostic examinations. However, PSA is best suited as a marker of cancer relapse after initial treatment. In this review, we first narratively describe the evolution of histological grading, the current status of Gleason pattern-based diagnostics and glance into future methodology of risk assessment by histological examination. In the second part, we systematically review the biomarkers that have been shown, independent from clinical characteristics, to correlate with clinically relevant end-points, i.e., occurrence of metastases, disease-specific mortality and overall survival after initial treatment of localized prostate cancer.

Abstract

Gleason grading remains the strongest prognostic parameter in localized prostate adenocarcinoma. We have here outlined the evolution and contemporary practices in pathological evaluation of prostate tissue samples for Gleason score and Grade group. The state of more observer-independent grading methods with the aid of artificial intelligence is also reviewed. Additionally, we conducted a systematic review of biomarkers that hold promise in adding independent prognostic or predictive value on top of clinical parameters, Grade group and PSA. We especially focused on hard end points during the follow-up, i.e., occurrence of metastasis, disease-specific mortality and overall mortality. In peripheral blood, biopsy-detected prostate cancer or in surgical specimens, we can conclude that there are more than sixty biomarkers that have been shown to have independent prognostic significance when adjusted to conventional risk assessment or grouping. Our search brought up some known putative markers and panels, as expected. Also, the synthesis in the systematic review indicated markers that ought to be further studied as part of prospective trials and in well characterized patient cohorts in order to increase the resolution of the current clinico-pathological prognostic factors.

Ablation of neuropilin-1 improves the therapeutic response in conventional drug-resistant glioblastoma multiforme

Glioblastoma multiforme (GBM) is a highly proliferative and locally invasive cancer with poor prognosis and a high recurrence rate. Although anti-VEGF (vascular endothelial growth factor) therapy offers short-term benefit to GBM patients, this approach fails as the tumor develops into a more invasive and drug-resistant phenotype and ultimately recurs. Recently, both glioma stemlike cells (GSCs) and brain tumor-initiating cells (BTICs) have been implicated in GBM recurrence and its resistance to therapy. We observed that patient-derived GBM cells expressing shRNAs of VEGF or neuropilin-1 (NRP-1) attenuate cancer stem cell markers, inhibit the tumor-initiating cell's neurosphere-forming capacity, and migration. Furthermore, both VEGF and NRP-1 knockdown inhibit the growth of patient-derived GBM xenografts in both zebrafish and mouse models. Interestingly, NRP-1-depleted patient-derived GBM xenografts substantially prolonged survival in mice compared to that of VEGF depletion. Our results also demonstrate that NRP-1 ablation of patient-derived GBM cells improves the sensitivity of TMZ and enhances the overall survival of the respective tumor-bearing mice. This improved outcome may provide insight into the inhibition of GBM progression and effective treatment strategies by targeting NRP-1 in addition to chemotherapy and radiotherapy.

miR-331-3p Suppresses Cell Proliferation in TNBC Cells by Downregulating NRP2

PURPOSE

Triple-negative breast cancer is characterized by fast progression with high possible for metastasis and poor survival. Dysfunction of microRNAs plays an important role in the initiation and progression of cancer. Our previous microRNA-seq data indicated the downregulation of miR-331-3p in triple-negative breast cancer tissues compared with that of the noncancer tissues. However, the function of miR-331-3p in triple-negative breast cancer remains largely unknown. Herein, the involvement of miR-331-3p in triple-negative breast cancer was investigated and the therapeutic potential of miR-331-3p was also explored.

METHODS

Real-time quantitative polymerase chain reaction was performed to detect the expression of miR-331-3p in triple-negative breast cancer tissues and cell lines. The cell proliferation was determined by the cell counting kit-8 assay. Apoptosis of triple-negative breast cancer cells was examined by annexin V/propidium iodide staining. miRDB database was used to predict the potential targets of miR-331-3p. Western blot was performed to examine the expression of the target protein.

RESULTS

miR-331-3p was significantly downregulated in triple-negative breast cancer tissues and cell line. Lower miR-331-3p expression was significantly correlated with the tumor size, TNM stage, and lymph node metastasis of patients with triple-negative breast cancer. Functional experiments showed that the overexpression of miR-331-3p inhibited the proliferation and increased apoptosis of triple-negative breast cancer cells. Neuropilin-2 was identified as a target of miR-331-3p, which harbored binding site of miR-331-3p in its 3'-untranslated region. Overexpression of miR-331-3p decreased the messenger RNA and protein levels of neuropilin-2 in triple-negative breast cancer cells. Restoration of neuropilin-2 partially reversed the inhibitory effects of miR-331-3p on the proliferation of triple-negative breast cancer cells.

CONCLUSIONS

Our results demonstrated the novel function of miR-331-3p/neuropilin-2 signaling in regulating the malignant behaviors of triple-negative breast cancer cells, which suggested miR-331-3p as a potential target for the treatment of triple-negative breast cancer.

Emerging Roles for Neuropilin-2 in Cardiovascular Disease

Cardiovascular disease, the leading cause of death worldwide, is predominantly associated with atherosclerosis. Atherosclerosis is a chronic inflammatory disease characterised by the narrowing of large to medium-sized arteries due to a build-up of plaque. Atherosclerotic plaque is comprised of lipids, extracellular matrix, and several cell types, including endothelial, immune, and vascular smooth muscle cells. Such narrowing of the blood vessels can itself restrict blood flow to vital organs but most severe clinical complications, including heart attacks and strokes, occur when lesions rupture, triggering the blood to clot and obstructing blood flow further down the vascular tree. To circumvent such obstructions, percutaneous coronary intervention or bypass grafts are often required; however, re-occlusion of the treated artery frequently occurs. Neuropilins (NRPs), a multifunctional family of cell surface co-receptors, are expressed by endothelial, immune, and vascular smooth muscle cells and are regulators of numerous signalling pathways within the vasculature. Here, we review recent studies implicating NRP2 in the development of occlusive vascular diseases and discuss how NRP2 could be targeted for therapeutic intervention.

Discovery of a novel fluorescent chemical probe suitable for evaluation of neuropilin-1 binding of small molecules

Neuropilin-1 (NRP1) is emerging as an important molecule in immune signaling where it has been shown to modulate the actions of TGF-β1 in macrophages and regulatory T cells. The development of cost-effective and reliable assays for NRP1 binding is therefore important. We synthesized three new NRP1 small molecule fluorophores and examined their performance as fluorescent polarization probes. One molecule DS108 exhibited favorable binding and fluorescent characteristics and allowed us to establish a simple assay suitable for medium to high throughput screening of small molecules.

Relationship between neuropilin-1 expression and prognosis, according to gastric cancer histology

Neuropilin-1 (NRP-1) is known to be related to various types of cancer and is considered a novel tumor marker or therapeutic target. The aim of this study was to identify the clinical implications of NRP-1 expression in terms of prognosis in patients with gastric cancer. A total of 265 patients who underwent radical gastrectomy for the treatment of gastric cancer from 2008 to 2011 were included in this retrospective study. NRP-1 expression of tumors was determined by immunohistochemistry. The patients' clinicopathological characteristics, operative details, and long-term outcomes were retrospectively analyzed. A total of 181 (68.3%) patients demonstrated expression of NRP-1. No survival difference was observed according to NRP-1 expression in any patient. The patients were divided into the gland formation (GF) and the no gland formation (nGF) types, according to histology. NRP-1 expression rates were 65.6% (84/128) and 70.8% (97/137), respectively. NRP-1 expression was not an independent prognostic factor in the GF group, although patients who expressed NRP-1 had better survival outcomes. In contrast, patients who expressed NRP-1 in the nGF group had worse 5-year survival rates (p = 0.027), and NRP-1 was an independent prognostic factor in a multivariate analysis (hazard ratio, 1.923; 95% confidence interval, 1.041-3.551). NRP-1 expression in patients with nGF type gastric cancer is predictive of a poor prognosis.

Comprehensive review of targeted therapy for colorectal cancer

Colorectal cancer (CRC) is among the most lethal and prevalent malignancies in the world and was responsible for nearly 881,000 cancer-related deaths in 2018. Surgery and chemotherapy have long been the first choices for cancer patients. However, the prognosis of CRC has never been satisfying, especially for patients with metastatic lesions. Targeted therapy is a new optional approach that has successfully prolonged overall survival for CRC patients. Following successes with the anti-EGFR (epidermal growth factor receptor) agent cetuximab and the anti-angiogenesis agent bevacizumab, new agents blocking different critical pathways as well as immune checkpoints are emerging at an unprecedented rate. Guidelines worldwide are currently updating the recommended targeted drugs on the basis of the increasing number of high-quality clinical trials. This review provides an overview of existing CRC-targeted agents and their underlying mechanisms, as well as a discussion of their limitations and future trends.

Revision of the Regioselectivity of the Beirut Reaction of Monosubstituted Benzofuroxans with Benzoylacetonitrile. 6-Substituted quinoxaline-2-carbonitrile 1,4- dioxides: Structural Characterization and Estimation of Anticancer Activity and Hypoxia Selectivity

BACKGROUND

Quinoxaline 1,4-dioxides have a broad range of biological activity that causes a growing interest in their derivatives for drug discovery. Recent studies demonstrated that quinoxaline 1,4- dioxides have a promising anticancer activity and good hypoxia-selectivity.

OBJECTIVE

The preparation, isolation, structure characterization, and screening for anticancer activity of the first representatives of 6-substituted quinoxaline-2-carbonitrile 1,4-dioxides have been described.

MATERIALS AND METHODS

A series of 7- and 6-halogeno-3-phenylquinoxaline-2-carbonitrile 1,4-dioxides was synthesized by the Beirut reaction. The cytotoxicity was assessed by MTT test (72 h incubation) in normoxia (21% O2) and hypoxia (1% O2) conditions.

RESULTS

We found that during the Beirut reaction between a benzofuroxan bearing an electron withdrawing group and benzoylacetonitrile in the presence of triethylamine, in addition to well-known 7-substituted quinoxaline-2-carbonitrile 1,4-dioxides 7-11a, the 6-isomers 7-11b are formed. Moreover, the yield of the 6- isomers increased with the increase in the electron-withdrawing character of the substituent. For benzofuroxans with CO2Me and CF3 groups, 6-substituted quinoxaline-2-carbonitrile 1,4-dioxides 10-11b were the major products. Despite similarities in physicochemical and spectroscopic properties, the obtained isomers exhibit considerable differences in their anticancer activity and hypoxia selectivity.

CONCLUSION

Substituents and their electronic effects play a key role in the formation of 7- and 6-substituted quinoxaline-2-carbonitrile 1,4-dioxides in the Beirut reaction and in the cytotoxicity properties of the obtained isomers.

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.

Open Data for Differential Network Analysis in Glioma

The complexity of cancer diseases demands bioinformatic techniques and translational research based on big data and personalized medicine. Open data enables researchers to accelerate cancer studies, save resources and foster collaboration. Several tools and programming approaches are available for analyzing data, including annotation, clustering, comparison and extrapolation, merging, enrichment, functional association and statistics. We exploit openly available data via cancer gene expression analysis, we apply refinement as well as enrichment analysis via gene ontology and conclude with graph-based visualization of involved protein interaction networks as a basis for signaling. The different databases allowed for the construction of huge networks or specified ones consisting of high-confidence interactions only. Several genes associated to glioma were isolated via a network analysis from top hub nodes as well as from an outlier analysis. The latter approach highlights a mitogen-activated protein kinase next to a member of histondeacetylases and a protein phosphatase as genes uncommonly associated with glioma. Cluster analysis from top hub nodes lists several identified glioma-associated gene products to function within protein complexes, including epidermal growth factors as well as cell cycle proteins or RAS proto-oncogenes. By using selected exemplary tools and open-access resources for cancer research and differential network analysis, we highlight disturbed signaling components in brain cancer subtypes of glioma.

Neuropilin 1 modulates TGF‑β1‑induced epithelial‑mesenchymal transition in non‑small cell lung cancer

Previously, the authors reported that neuropilin-1 (NRP1) was significantly increased and acted as a vital promoter in the metastasis of non-small cell lung cancer (NSCLC). However, the regulatory mechanism of NRP1 in NSCLC cell migration and invasion remained unclear. The present study aimed to explore the regulatory mechanism of NRP1 in the transforming growth factor-β (TGF-β) 1-induced migration and invasion of NSCLC cells. The expression level of NRP1 was determined by RT-qPCR analysis in human tissue samples with or without lymph node metastasis. Transwell assay and wound healing assay were conducted to determine the cell migration. Lentivirus-mediated stable knockdown and overexpression of NRP1 cell lines were constructed. Exogenous TGF-β1 stimulation, SIS3 treatment, western blot analysis and in vivo metastatic model were utilized to clarify the underlying regulatory mechanisms. The results demonstrated that the expression of NRP1 was increased in metastatic NSCLC tissues. NRP1 promoted NSCLC metastasis in vitro and in vivo. The Transwell assays, wound healing assays and western blot analysis revealed that the knockdown of NRP1 significantly inhibited TGF-β1-mediated EMT and migratory and invasive capabilities of NSCLC. Furthermore, the overexpression of NRP1 weakened the inhibitory effect of SIS3 on the NSCLC migration and invasion. Co-IP assay revealed that NRP1 interacted with TGFβRII to induce EMT. On the whole, the findings of this study demonstrated that NRP1 was overexpressed in metastatic NSCLC tissues. NRP1 could contributes to TGF-β1-induced EMT and metastasis in NSCLC by binding with TGFβRII.

VEGF-A-Cleavage by FSAP and Inhibition of Neo-Vascularization

Alternative splicing leads to the secretion of multiple forms of vascular endothelial growth factor-A (VEGF-A) that differ in their activity profiles with respect to neovascularization. FSAP (factor VII activating protease) is the zymogen form of a plasma protease that is activated (FSAPa) upon tissue injury via the release of histones. The purpose of the study was to determine if FSAPa regulates VEGF-A activity in vitro and in vivo. FSAP bound to VEGF₁₆₅, but not VEGF₁₂₁, and VEGF₁₆₅ was cleaved in its neuropilin/proteoglycan binding domain. VEGF₁₆₅ cleavage did not alter its binding to VEGF receptors but diminished its binding to neuropilin. The stimulatory effects of VEGF₁₆₅ on endothelial cell proliferation, migration, and signal transduction were not altered by FSAP. Similarly, proliferation of VEGF receptor-expressing BAF3 cells, in response to VEGF₁₆₅, was not modulated by FSAP. In the mouse matrigel model of angiogenesis, FSAP decreased the ability of VEGF₁₆₅, basic fibroblast growth factor (bFGF), and their combination, to induce neovascularization. Lack of endogenous FSAP in mice did not influence neovascularization. Thus, FSAP inhibited VEGF₁₆₅-mediated angiogenesis in the matrigel model in vivo, where VEGF’s interaction with the matrix and its diffusion are important.

The VEGF receptor neuropilin 2 promotes homologous recombination by stimulating YAP/TAZ-mediated Rad51 expression

Vascular endothelial growth factor (VEGF) signaling in tumor cells mediated by neuropilins (NRPs) contributes to the aggressive nature of several cancers, including triple-negative breast cancer (TNBC), independently of its role in angiogenesis. Understanding the mechanisms by which VEGF-NRP signaling contributes to the phenotype of such cancers is a significant and timely problem. We report that VEGF-NRP2 promote homologous recombination (HR) in BRCA1 wild-type TNBC cells by contributing to the expression and function of Rad51, an essential enzyme in the HR pathway that mediates efficient DNA double-strand break repair. Mechanistically, we provide evidence that VEGF-NRP2 stimulates YAP/TAZ-dependent Rad51 expression and that Rad51 is a direct YAP/TAZ-TEAD transcriptional target. We also discovered that VEGF-NRP2-YAP/TAZ signaling contributes to the resistance of TNBC cells to cisplatin and that Rad51 rescues the defects in DNA repair upon inhibition of either VEGF-NRP2 or YAP/TAZ. These findings reveal roles for VEGF-NRP2 and YAP/TAZ in DNA repair, and they indicate a unified mechanism involving VEGF-NRP2, YAP/TAZ, and Rad51 that contributes to resistance to platinum chemotherapy.

Triazolopeptides Inhibiting the Interaction between Neuropilin-1 and Vascular Endothelial Growth Factor-165

Inhibiting the interaction of neuropilin-1 (NRP-1) with vascular endothelial growth factor (VEGF) has become an interesting mechanism for potential anticancer therapies. In our previous works, we have obtained several submicromolar inhibitors of this interaction, including branched pentapeptides of general structure Lys(Har)-Xxx-Xxx-Arg. With the intent to improve the proteolytic stability of our inhibitors, we turned our attention to 1,4-disubstituted 1,2,3-triazoles as peptide bond isosteres. In the present contribution, we report the synthesis of 23 novel triazolopeptides along with their inhibitory activity. The compounds were synthesized using typical peptide chemistry methods, but with a conversion of amine into azide completely on solid support. The inhibitory activity of the synthesized derivatives spans from 9.2% to 58.1% at 10 μM concentration (the best compound Lys(Har)-GlyΨ[Trl]GlyΨ[Trl]Arg, 3, IC₅₀ = 8.39 μM). Synthesized peptidotriazoles were tested for stability in human plasma and showed remarkable resistance toward proteolysis, with half-life times far exceeding 48 h. In vitro cell survival test resulted in no significant impact on bone marrow derived murine cells 32D viability. By means of molecular dynamics, we were able to propose a binding mode for compound 3 and discuss the observed structure–activity relationships.

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.