Neuropilin-2 promotes melanoma growth and progression in vivo

Tretinoin (2,4-difluoro-phenyl) triazole activates proapoptotic protein expression and targets NRP2 protein to inhibit esophageal carcinoma cell growth

The present study investigated the effect of tretinoin (2,4-difluoro-phenyl) triazole (TDFPT) on the growth and proliferation of Kyse-270 and EC9706 esophageal carcinoma cells and explored the underlying mechanism. The results demonstrated that TDFPT treatment of Kyse-270 and EC9706 cells led to a dose-dependent reduction in cell proliferation. Colony formation was significantly (p < .05) reduced in Kyse-270 and EC9706 cells on treatment with various concentrations of TDFPT. In TDFPT-treated Kyse-270 and EC9706 cells, the expression of Bcl-2 protein showed a remarkable decrease, whereas the level of Bax protein was found to be higher compared with the control cells. Cell invasion showed a prominent decrease in Kyse-270 and EC9706 cells on treatment with TDFPT. Treatment with TDFPT led to a prominent suppression in the expression of MMP-9 and NRP2 in Kyse-270 and EC9706 cells. In silico studies using the AutoDock Vina and discovery studio software revealed that various confirmations of TDFPT bind to NRP2 protein with the affinity ranging from -8.6 to -6.1 kcal/mol. It was found that the TDFPT interacts with NRP2 protein by binding to alanine (ALA A:295), proline (PRO A:306), glutamine (GLN A:307), and isoleucine (ILE A:293) amino acid residues. In summary, TDFPT exposure suppresses esophageal carcinoma cell proliferation, inhibits colony formation ability, and activates apoptotic pathway. Thus, TDFPT acts as an effective antiproliferative agent for esophageal carcinoma cells and needs to be investigated further as chemotherapeutic molecule.

Is neuropilin-1 the neuroimmune initiator of multi-system hyperinflammation in COVID-19?

A major immunopathological feature of Coronavirus disease-2019 (COVID-19) is excessive inflammation in the form of "cytokine storm". The storm is characterized by injurious levels of cytokines which form a complicated network damaging different organs, including the lungs and the brain. The main starter of "cytokine network" hyperactivation in COVID-19 has not been discovered yet. Neuropilins (NRPs) are transmembrane proteins that act as neuronal guidance and angiogenesis modulators. The crucial function of NRPs in forming the nervous and vascular systems has been well-studied. NRP1 and NRP2 are the two identified homologs of NRP. NRP1 has been shown as a viral entry pathway for SARS-CoV2, which facilitates neuroinvasion by the virus within the central or peripheral nervous systems. These molecules directly interact with various COVID-19-related molecules, such as specific regions of the spike protein (major immune element of SARS-CoV2), vascular endothelial growth factor (VEGF) receptors, VEGFR1/2, and ANGPTL4 (regulator of vessel permeability and integrity). NRPs mainly play a role in hyperinflammatory injury of the CNS and lungs, and also the liver, kidney, pancreas, and heart in COVID-19 patients. New findings have suggested NRPs good candidates for pharmacotherapy of COVID-19. However, therapeutic targeting of NRP1 in COVID-19 is still in the preclinical phase. This review presents the implications of NRP1 in multi-organ inflammation-induced injury by SARS-CoV2 and provides insights for NRP1-targeting treatments for COVID-19 patients.

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.

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

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

The Spatial Landscape of Progression and Immunoediting in Primary Melanoma at Single-Cell Resolution

Cutaneous melanoma is a highly immunogenic malignancy that is surgically curable at early stages but life-threatening when metastatic. Here we integrate high-plex imaging, 3D high-resolution microscopy, and spatially resolved microregion transcriptomics to study immune evasion and immunoediting in primary melanoma. We find that recurrent cellular neighborhoods involving tumor, immune, and stromal cells change significantly along a progression axis involving precursor states, melanoma in situ, and invasive tumor. Hallmarks of immunosuppression are already detectable in precursor regions. When tumors become locally invasive, a consolidated and spatially restricted suppressive environment forms along the tumor-stromal boundary. This environment is established by cytokine gradients that promote expression of MHC-II and IDO1, and by PD1-PDL1-mediated cell contacts involving macrophages, dendritic cells, and T cells. A few millimeters away, cytotoxic T cells synapse with melanoma cells in fields of tumor regression. Thus, invasion and immunoediting can coexist within a few millimeters of each other in a single specimen.

SIGNIFICANCE

The reorganization of the tumor ecosystem in primary melanoma is an excellent setting in which to study immunoediting and immune evasion. Guided by classic histopathology, spatial profiling of proteins and mRNA reveals recurrent morphologic and molecular features of tumor evolution that involve localized paracrine cytokine signaling and direct cell-cell contact. This article is highlighted in the In This Issue feature, p. 1397.

SEMAPHORINS and their receptors: focus on the crosstalk between melanoma and hypoxia

Hypoxia, a condition of oxygen deprivation, is considered a hallmark of tumor microenvironment regulating several pathways and promoting cancer progression and resistance to therapy. Semaphorins, a family of about 20 secreted, transmembrane and GPI-linked glycoproteins, and their cognate receptors (plexins and neuropilins) play a pivotal role in the crosstalk between cancer and stromal cells present in the tumor microenvironment. Many studies reported that some semaphorins are involved in the development of a permissive tumor niche, guiding cell-cell communication and, consequently, the development and progression, as well as the response to therapy, of different cancer histotypes, including melanoma.

In this review we will summarize the state of art of semaphorins regulation by hypoxic condition in cancer with different origin. We will also describe evidence about the ability of semaphorins to affect the expression and activity of transcription factors activated by hypoxia, such as hypoxia-inducible factor-1. Finally, we will focus our attention on findings reporting the role of semaphorins in melanocytes transformation, melanoma progression and response to therapy. Further studies are necessary to understand the mechanisms through which semaphorins induce their effect and to shed light on the possibility to use semaphorins or their cognate receptors as prognostic markers and/or therapeutic targets in melanoma or other malignancies.

New insights into the role of co-receptor neuropilins in tumour angiogenesis and lymphangiogenesis and targeted therapy strategies

Local tumour sites lead to pathological angiogenesis and lymphangiogenesis due to malignant conditions such as hypoxia. Although VEGF and VEGFR are considered to be the main anti-tumour treatment targets, the problems of limited efficacy and observable side effects of some drugs relevant to this target still remain to be solved. Therefore, it is necessary to identify new therapeutic targets for angiogenesis or lymphangiogenesis. The neuropilin family is a class of single transmembrane glycoprotein receptors, including neuropilin1 (NRP1) and neuropilin2 (NRP2), which could act as co-receptors of VEGFA-165 and VEGFC and play a key role in promoting tumour proliferation, invasion and metastasis. In this review, we introduced the schematic diagram to visually reveal the function of NRP1 and NRP2 in enhancing the binding affinity of VEGFR2 to VEGFA-165 and VEGFR3 to VEGFC, respectively. We also discussed the signalling pathways that depend on the co-receptors NRP1 and NRP2 and some existing targeted therapeutic strategies, such as monoclonal antibodies, targeted peptides, microRNAs and small molecule inhibitors. It will contribute a vital foundation for the future research and development of new drugs targeting NRPs. HIGHLIGHTS NRP1 acts as a co-receptor with VEGFR2 and the pro-angiogenic factor VEGFA-165 to up-regulate tumour angiogenesis by promoting endothelial cells proliferation, survival, migration, invasion and by preventing of apoptosis. NRP2 acts as a co-receptor with VEGFR3 and the pro-lymphogenic factor VEGFC to facilitate tumour metastasis by promoting lymphangiogenesis. Although NRP1 and NRP2 do not have enzymatic signalling activity, the affinity of VEGFR2 for VEGFA-165 and VEGFR3 for VEGFC can increase in a co-receptor manner, as detailed in the schematic. The exclusive roles of NRP1 and NRP2 in signalling pathways are specifically described to emphasise the molecular regulatory mechanisms involved in co-receptors. Various studies have shown that the co-receptors NRP1 and NRP2 can be directly or indirectly targeted by different methods to prevent tumour angiogenesis and lymphangiogenesis. Therapeutic strategies targeting NRPs look promising soon as evidenced by preclinical and clinical studies.

Enhanced Anticancer Effect of a Combination of S-adenosylmethionine (SAM) and Immune Checkpoint Inhibitor (ICPi) in a Syngeneic Mouse Model of Advanced Melanoma

Immune checkpoint inhibitors (ICPi) targeting the PD-1/PD-L1 pathway have shown marked success in patients with advanced melanoma. However, 60-70% of patients fail to respond, warranting a therapeutic intervention that could increase response rates. We and others have shown that S-adenosylmethionine (SAM), a universal methyl donor, has significant anticancer effects in numerous cancers previously; however, its effect on melanoma progression has not been evaluated. Interestingly, SAM was reported to be essential for T cell activation and proliferation and, thus, could potentially cooperate with ICPi and block melanoma progression. In this study, we examined the antitumor effects of SAM and ICPi alone and in combination in a well-established melanoma mouse model wherein syngeneic C57BL/6 mouse were subcutaneously (orthotopic) injected with B16-F1 cells. Treatment of mice with either SAM or anti-PD-1 antibody alone resulted in significant reduction in tumor volumes and weights; effects that were highest in mice treated with a combination of SAM+anti-PD-1. RNA-sequencing analysis of the primary tumors showed numerous differentially expressed genes (DEGs) following treatment with SAM+anti-PD-1, which was shown to downregulate cancer, MAPK, and tyrosine kinase pathways. Indeed, SAM+anti-PD-1 reversed the aberrant expression of some known melanoma genes. Tumor immunophenotyping revealed the SAM+anti-PD-1 combination was significantly more effective than either SAM or anti-PD-1 as the CD8⁺ T cells had higher activation, proliferation, and cytokine production compared to all other groups. This study shows that the combination of currently approved agents SAM and ICPi can effectively block melanoma via alteration of key genes/pathways implicated in cancer and immune response pathways, providing the rationale for the initiation of clinical trials with SAM and ICPi.

Neuropilin-2 promotes growth and progression of papillary thyroid cancer cells

OBJECTIVE

Neuropilin-2 (NRP2) is a coreceptor of vascular endothelial growth factor-C/D (VEGF-C/D) and plays the important role in the development of lymphatic endothelial cells, as well as neuronal development. NRP2 is known to affect aggressiveness by increasing expression in various human cancers, but the role of NRP2 in thyroid cancer is not fully understood. The purpose of this study was to investigate the NRP2 expression and its role in regulating the tumor aggressiveness in the papillary thyroid carcinoma (PTC).

METHODS

The NRP2 expression and its clinicopathologic correlation to PTC was determined using the data from the 262 PTC patients at a tertiary referral medical center and The Cancer Genome Atlas (TCGA) database. The potential role of NRP2 in modulating tumor growth, invasion, and metastasis in PTC was examined by using small interfering RNA (siRNA)-mediated knockdown of NRP2.

RESULTS

High expression of NRP2 was significantly associated with capsular invasion, lymphovascular invasion, lymph node metastasis, 5 or more metastatic lymph nodes, and recurrence in PTC patients. In TCGA data, the higher NRP2 expression group was significantly associated with extrathyroid extension, lymph node metastasis, and BRAF^V600E mutation. The siRNA mediated knockdown of NRP2 in the PTC cells reduced the cell proliferation, migration and invasion. We also have confirmed that NRP2 knockdown suppressed epithelial-mesenchymal transition (EMT) by regulating AKT and ERK phosphorylation signaling pathways.

CONCLUSION

Our results suggest that NRP2 regulates tumor progression in PTC and may act as a predictive factor for aggressiveness of PTC.

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.

miR-331-3p suppresses cell invasion and migration in colorectal carcinoma by directly targeting NRP2

Colorectal carcinoma (CRC) is a common tumor of the digestive system with poor prognosis. Studies have shown that aberrant microRNA (miRNA) expression can affect CRC progression by regulating target genes. In the present study, we investigated the functional roles and potential mechanisms of miR-331-3p in CRC. The expression of miR-331-3p and neuropilin-2 (NRP2) in CRC was detected by RT-qPCR. Then, Transwell assays were conducted to investigate the influence of miR-331-3p on CRC cell invasion and migration abilities. Luciferase reporter assays were performed to determine the target gene of miR-331-3p. It was found that miR-331-3p expression was notably declined in CRC and inversely correlated with the NRP2 expression. miR-331-3p upregulation significantly inhibited CRC cell invasion and migration. Additionally, western blot analysis demonstrated that miR-331-3p restoration evidently suppressed CRC cell EMT. Moreover, NRP2 was conformed to be a novel target of miR-331-3p and knockdown of NRP2 partially inversed the effects of the miR-331-3p inhibitor on cell invasion and migration. These results suggested that miR-331-3p exerted tumor suppressive roles in CRC by targeting NRP2 and miR-331-3p/NRP2 may serve as a potential therapy for CRC.

Roles for VEGF-C/NRP-2 axis in regulating renal tubular epithelial cell survival and autophagy during serum deprivation

Vascular endothelial growth factor C (VEGF-C) is an angiogenic and lymphangiogenic growth factor. Recent research has revealed the role for VEGF-C in regulating autophagy by interacting with a nontyrosine kinase receptor, neuropilin-2 (NRP-2). However, whether VEGF-C participates in regulating cell survival and autophagy in renal proximal tubular cells is unknown. To address this question, we employed a cell modal of serum deprivation to verify the role of VEGF-C and its receptor NRP-2 in regulating cell survival and autophagy in NRK52E cell lines. The results show that VEGF-C rescued the loss of cell viability induced by serum deprivation in a concentration-dependent manner. Furthermore, endogenous VEGF-C was knocked down in NRK52E cells by using specific small-interfering RNAs (siRNA), cells were more sensitive to serum deprivation-induced cell death. A similar increase in cell death rate was observed following NRP-2 depletion in serum-starved NRK52E cells. Autophagy activity in serum-starved NRK52E cells was confirmed by western blot analysis of microtubule-associated protein-1 chain 3 (LC3), immunofluorescence staining of endogenous LC3, and the formation of autophagosomes by electron microscopy. VEGF-C or NRP-2 depletion further increased LC3 expression induced by serum deprivation, suggesting that VEGF-C and NRP-2 were involved in controlling autophagy in NRK52E cells. We further performed autophagic flux experiments to identify that VEGF-C promotes the activation of autophagy in serum-starved NRK52E cells. Together, these results suggest for the first time that VEGF-C/NRP-2 axis promotes survival and autophagy in NRK52E cells under serum deprivation condition. SIGNIFICANCE OF THE STUDY: More researchers had focused on the regulation of autophagy in kidney disease. The effect of VEGF-C on cell death and autophagy in renal epithelial cells has not been examined. We first identified the VEGF-C as a regulator of cell survival and autophagy in NRK52E cell lines. And VEGF-C/NRP-2 may mediate autophagy by regulating the phosphorylation of 4EBP1 and P70S6K. VEGF-C treatment may be identified as a therapeutic target in renal injury repair due to its capacity to promote tubular cell survival in the future.

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.

Oncogenic Metabolism Acts as a Prerequisite Step for Induction of Cancer Metastasis and Cancer Stem Cell Phenotype

Metastasis is a major obstacle to the efficient and successful treatment of cancer. Initiation of metastasis requires epithelial-mesenchymal transition (EMT) that is regulated by several transcription factors, including Snail and ZEB1/2. EMT is closely linked to the acquisition of cancer stem cell (CSC) properties and chemoresistance, which contribute to tumor malignancy. Tumor suppressor p53 inhibits EMT and metastasis by negatively regulating several EMT-inducing transcription factors and regulatory molecules; thus, its inhibition is crucial in EMT, invasion, metastasis, and stemness. Metabolic alterations are another hallmark of cancer. Most cancer cells are more dependent on glycolysis than on mitochondrial oxidative phosphorylation for their energy production, even in the presence of oxygen. Cancer cells enhance other oncogenic metabolic pathways, such as glutamine metabolism, pentose phosphate pathway, and the synthesis of fatty acids and cholesterol. Metabolic reprogramming in cancer is regulated by the activation of oncogenes or loss of tumor suppressors that contribute to tumor progression. Oncogenic metabolism has been recently linked closely with the induction of EMT or CSC phenotypes by the induction of several metabolic enzyme genes. In addition, several transcription factors and molecules involved in EMT or CSCs, including Snail, Dlx-2, HIF-1α, STAT3, TGF-β, Wnt, and Akt, regulate oncogenic metabolism. Moreover, p53 induces metabolic change by directly regulating several metabolic enzymes. The collective data indicate the importance of oncogenic metabolism in the regulation of EMT, cell invasion and metastasis, and adoption of the CSC phenotype, which all contribute to malignant transformation and tumor development. In this review, we highlight the oncogenic metabolism as a key regulator of EMT and CSC, which is related with tumor progression involving metastasis and chemoresistance. Targeting oncometabolism might be a promising strategy for the development of effective anticancer therapy.

Transforming growth factor-β1 promotes breast cancer metastasis by downregulating miR-196a-3p expression

Transforming growth factor-β1 is considered a key contributor to the progression of breast cancer. MicroRNAs are important factors in the development and progression of many malignancies. In the present study, upon studies of breast cancer cell lines and tissues, we showed that microRNA -196a-3p is decreased by transforming growth factor-β1 in breast cancer cells and associated with breast cancer progression. We identified neuropilin-2 as a target gene of microRNA -196a-3p and showed that it is regulated by transforming growth factor-β1. Moreover, transforming growth factor-β1-mediated inhibition of microRNA -196a-3p and activation of neuropilin-2were required for transforming growth factor-β1-induced migration and invasion of breast cancer cells. In addition, neuropilin-2 expression was suppressed in breast tumors, particularly in triple-negative breast cancers. Collectively, our findings strongly indicate that microRNA -196a-3p is a predictive biomarker of breast cancer metastasis and patient survival and a potential therapeutic target in metastatic breast cancer.

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.

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.