Long non‑coding RNA 00152 functions as a competing endogenous RNA to regulate NRP1 expression by sponging with miRNA‑206 in colorectal cancer

LINC00152: Potential driver oncogene in pan-cancer

Long noncoding RNAs (lncRNA) are a class of non-coding RNAs greater than 200 bp in length with limited peptide-coding function. The transcription of LINC00152 is derived from chromosome 2p11.2. Many studies prove that LINC00152 influences the progression of various tumors via promoting the tumor cells malignant phenotype, chemoresistance, and immune escape. LINC00152 is regulated by multiple transcription factors and DNA hypomethylation. In addition, LINC00152 participates in the regulation of complex molecular signaling networks through epigenetic regulation, protein interactions, and competitive endogenous RNA (ceRNA). Here, we provide a systematic review of the upstream regulatory factors of LINC00152 expression level in different types of tumors. In addition, we revisit the main functions and mechanisms of LINC00152 as driver oncogene and biomarker in pan-cancer. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Methods > RNA Analyses in Cells RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.

CAFs-derived small extracellular vesicles circN4BP2L2 promotes proliferation and metastasis of colorectal cancer via miR-664b-3p/HMGB3 pathway

Our previous research has demonstrated that colorectal cancer (CRC) progression was promoted by circN4BP2L2. This study aimed to further explore the mechanism of circN4BP2L2 in the development of CRC from the perspective of small extracellular vesicles (sEVs). Cancer-associated fibroblasts cell (CAFs) and normal fibroblasts cell (NFs) were isolated from CRC tissues and adjacent tissues, respectively. The ultra-centrifugation was used for extraction of their related sEVs. Cell proliferation and apoptosis were analyzed using CCK-8 and flow cytometry, respectively. Transwell assay was conducted to measure cell migration. The tube formation ability was assessed by tube formation assay. The target relationships between circN4BP2L2 and miR-664b-3p, and miR-664b-3p and HMGB3 were validated by dual-luciferase reporter detection. The effect of CAFs-derived sEV (CAFs-sEVs) circN4BP2L2 on CRC was further studied in nude mice. CAFs-exo promoted cell proliferation, migration, tube formation ability, and inhibited apoptosis of CRC cells. CAFs-sEV circN4BP2L2 knockdown reversed the above results. CircN4BP2L2 directly targeted miR-664b-3p, and HMGB3 was targeted by miR-664b-3p. Moreover, subcutaneous tumorigenesis and liver metastasis of nude mice with CRC were repressed by CAFs-sEV circN4BP2L2 knockdown. CAFs-sEV circN4BP2L2 knockdown restrained CRC cell proliferation and migration by regulating miR-664b-3p/HMGB3 pathway.

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.

LINC00707 Promotes Cell Proliferation in Cervical Cancer via the miR-374c-5p/SDC4 Axis

Cervical cancer (CC) is the second main reason of cancer-related deaths in women around the world. Long intergenic nonprotein coding RNA 707, which is known as LINC00707, has been elucidated to facilitate the progression of multifarious tumors, but how it may exert functions in CC has not been elucidated yet. By using quantitative real-time RT-PCR (RT-qPCR), we identified the expression pattern LINC00707 may possess in CC. Loss-of-function assays including Cell Counting Kit-8 (CCK-8), colony formation, and transferase-mediated dUTP nick-end labeling (TUNEL) assays were taken to verify the effects of LINC00707 inhibition on CC cell proliferation and apoptosis. The downstream RNAs were selected through bioinformatics prediction, and their interaction with LINC00707 was verified through mechanism assays including the luciferase reporter assay, RNA pull-down assay, and RNA immunoprecipitation (RIP) assay. According to results, LINC00707 was upregulated in CC cells, and LINC00707 insufficiency inhibited cell proliferation while facilitating cell apoptosis. MicroRNA (miRNA) miR-374c-5p interacted with LINC00707, and syndecan-4 (SDC4) was verified to be the downstream target gene. Data of rescue assays proved that LINC00707 could promote CC cell malignancy via the miR-374c-5p/SDC4 axis, which revealed a potential treatment option for CC.

A Circ-0007022/miR-338-3p/Neuropilin-1 Axis Reduces the Radiosensitivity of Esophageal Squamous Cell Carcinoma by Activating Epithelial-To-Mesenchymal Transition and PI3K/AKT Pathway

Radiotherapy resistance is an important cause of treatment failure in esophageal squamous cell carcinoma (ESCC). Circular RNAs have attracted a lot of attention in cancer research, but their role in ESCC radiosensitivity has not been elucidated yet. Here, we aimed to evaluated the functional impacts of circ-0007022 on ESCC radiosensitivity. In this study, a stable radiotherapy-resistant cell line was established and verified by a series of functional experiments. Subsequently, high-throughput sequencing revealed that circ-0007022 was significantly overexpressed in the radiotherapy-resistant cell line and this conclusion was verified in ESCC patients’ tumor tissues by real-time quantitative PCR. Moreover, loss-of-function and overexpression experiments in vitro and in vivo revealed that, after irradiation, the abilities of proliferation and migration in circ-0007022-overexpressing stable transgenic strain were significantly higher than that in circ-0007022-knockdown stable transgenic strain. Additionally, RNA Immunoprecipitation, RNA pull-down, luciferase reporter assays, and fluorescence in situ hybridization experiments demonstrated the mechanism of how circ-0007022 could sponge miR-338-3p and upregulate downstream target of miR-338-3p, neuropilin-1 (NRP1). Moreover, NRP1 led to poor prognosis for ESCC patients receiving radiotherapy, and NRP1 knock-down enhanced radiosensitivity of ESCC cells. Furthermore, circ-0007022 overexpression activated Epithelial-to-mesenchymal transition and PI3K/Akt pathway, and NRP1 knock-down could reversed this phenomenon. Finally, Akt Inhibitor reversed circ-0007022s role in radiotherapy in ESCC cells. Taken together, the circ-0007022/miR-338-3p/NRP1 axis enhances the radiation resistance of ESCC cells via regulating EMT and PI3K/Akt pathway. The new circRNA circ-0007022 is thus expected to be a therapeutic target for ESCC patients.

Functional Peptides Encoded by Long Non-Coding RNAs in Gastrointestinal Cancer

Gastrointestinal cancer is by far the most common malignancy and the most common cause of cancer-related deaths worldwide. Recent studies have shown that long non-coding RNAs (lncRNAs) play an important role in the epigenetic regulation of cancer cells and regulate tumor progression by affecting chromatin modifications, gene transcription, translation, and sponge to miRNAs. In particular, lncRNA has recently been found to possess open reading frame (ORF), which can encode functional small peptides or proteins. These peptides interact with its targets to regulate transcription or the signal axis, thus promoting or inhibiting the occurrence and development of tumors. In this review, we summarize the involvement of lncRNAs and the function of lncRNAs encoded small peptides in gastrointestinal cancer.

Research updates on the clinical implication of long noncoding RNA in digestive system cancers and chemoresistance

Long noncoding RNAs (lncRNAs) are implicated in various biological processes, such as cell proliferation, differentiation, apoptosis, migration, and invasion. They are also key players in various biological pathways. LncRNA was considered as 'translational noise' before 1980s. It has been reported that lncRNAs are aberrantly expressed in different cancers, either as oncogene or tumor suppressor gene. Therefore, more and more lncRNAs are recognized as potential diagnostic biomarkers and/or therapeutic targets. As competitive endogenous RNA, lncRNAs can interact with microRNA to alter the expression of target genes, which may have extensive clinical implications in cancers, including diagnosis, treatment, prognosis, and chemoresistance. This review comprehensively summarizes the functions and clinical relevance of lncRNAs in digestive system cancers, especially as a potential tool to overcome chemoresistance.

LncRNA SOX2-OT/miR-30d-5p/PDK1 Regulates PD-L1 Checkpoint Through the mTOR Signaling Pathway to Promote Non-small Cell Lung Cancer Progression and Immune Escape

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. Currently, treatment methods generally cause poor prognosis. Therefore, in order to seek new treatment options, we explored the internal mechanism of NSCLC. Firstly, the SOX2-OT/miR-30d-5p/PDK1 axis regulated by lncRNA SOX2-OT was predicted by bioinformatics methods, and the expression of SOX2-OT, miR-30d-5p, and PDK1 mRNA in cells were detected by qRT-PCR while PDK1 protein expression was detected by western blot. The results expressed that in NSCLC, SOX2-OT, and PDK1 were notably overexpressed while miR-30d-5p was markedly under-expressed. The interaction between them was verified by dual-luciferase reporter and RNA binding protein immunoprecipitation assays. Subsequently, through CCK8, scratch healing, cell invasion and flow cytometry assays, we revealed that inhibiting the expression of SOX2-OT could inhibit the proliferation, migration and invasion of NSCLC cells and promote cell apoptosis; while simultaneous overexpression of PDK1 or inhibition of miR-30d-5p expression could reverse the inhibitory effect of SOX2-OT silence-mediated malignant progression of NSCLC cells. Then, the combined application of overexpressed PDK1 and rapamycin verified that PDK1 could regulate the expression of PD-L1 in NSCLC cells through the mTOR signaling pathway. Co-culture of CD8⁺ T cells verified that silencing SOX2-OT could inhibit the apoptosis of CD8⁺ T cells through miR-30d-5p/PDK1. Finally, tumor formation assay in animals confirmed that overexpression of SOX2-OT could promote the growth of NSCLC tumor in vivo. In this study, assays in vitro and in vivo were conducted to elucidate the mechanism by which SOX2-OT/miR-30d-5p/PDK1 drives PD-L1 through the mTOR signaling pathway to promote the malignant progression and immune escape of NSCLC.

Impaired AGO2/miR-185-3p/NRP1 axis promotes colorectal cancer metastasis

Increasing evidence suggests that global downregulation of miRNA expression is a hallmark of human cancer, potentially due to defects in the miRNA processing machinery. In this study, we found that the protein expression of Argonaute 2 (AGO2), a key regulator of miRNA processing, was downregulated in colorectal cancer (CRC) tissues, which was also consistent with the findings of the Clinical Proteomic Tumor Analysis Consortium (CPTAC). Furthermore, the correlation between the levels of AGO2 and epithelial-mesenchymal transition (EMT) markers (E-cadherin and vimentin) indicated that reduced levels of AGO2 promoted EMT in CRC. Low expression of AGO2 was an indicator of a poor prognosis among CRC patients. Knockdown of AGO2 in CRC cells promoted migration, invasion and metastasis formation in vitro and in vivo but had no influence on proliferation. To provide detailed insight into the regulatory roles of AGO2, we performed integrated transcriptomic, quantitative proteomic and microRNA sequencing (miRNA-seq) analyses of AGO2 knockdown cells and the corresponding wild-type cells and identified neuropilin 1 (NRP1) as a new substrate of AGO2 via miR-185-3p. Our data provided evidence that knockdown of AGO2 resulted in a reduction of miR-185-3p expression, leading to the upregulation of the expression of NRP1, which is a direct target of miR-185-3p, and elevated CRC cell metastatic capacity. Inhibition of NRP1 or treatment with a miR-185-3p mimic successfully rescued the phenotypes of impaired AGO2, which suggested that therapeutically targeting the AGO2/miR-185-3p/NRP1 axis may be a potential treatment approach for CRC.

LINC00152 mediates CD8+ T-cell infiltration in gastric cancer through binding to EZH2 and regulating the CXCL9, 10/CXCR3 axis

This study aimed to annotate the role of long intergenic non-coding RNA 152 (LINC00152) in CD8⁺ T cells mediated immune responses in gastric cancer (GC) and the underlying mechanism. LINC00152 expression levels were detected through RT-PCR. For tumor engraftment, HGC-27 cells that received LINC00152 shRNA, LINC00152 overexpression vectors, enhancer of zeste homolog 2 (EZH2) shRNA or combination transfection were injected into mice. Chromatin immunoprecipitation (ChIP) assay was used to explore the interaction between LINC00152, Cys-X-cys ligand 9 (CXCL9) and Cys-X-cys ligand 10 (CXCL10). Flow cytometry was adopted to measure the CD8⁺ T-cell infiltration in tumor issue. In this study, we found increased LINC00152 expression levels are positively associated with the poor prognosis of GC patients and negatively associated with the CD8 levels. ChIP assay verified that LINC00152 recruits EZH2 to the promoters of CXCL9 and CXCL10, thus the silencing of LINC00152 promoted the production of CXCL9 and CXCL10. Knockdown of LINC00152 suppressed tumor cells growth in vivo and in vitro, increased tumor-infiltrating CD8⁺ T cells numbers and promoted the expression of CXCL9, CXCL10 and C-X-C Motif Chemokine Receptor 3 (CXCR3) in xenograft tumors. While CD8⁺ T cell depletion reversed the tumor suppression effect of LINC00152 silence. Besides, the silencing of EZH2 partly inhibited the promotion effect LINC00152 on tumor growth. Our study indicated that LINC00152 inhibition suppressed the tumor progress may through promoting CD8⁺ T-cell infiltration.

Sp1-mediated up-regulation of lnc00152 promotes invasion and metastasis of retinoblastoma cells via the miR-30d/SOX9/ZEB2 pathway

PURPOSE

Previously, we found that long non-coding RNA (lncRNA) MEG3 may act as a tumour suppressor in retinoblastoma. Overall, however, little is known about the role of lncRNAs in retinoblastoma. Here, we aimed to determine the expression and clinical significance of lnc00152 in retinoblastoma.

METHODS

Lnc00152 and its downstream targets were selected using GEO datasets. The level of lnc00152 in primary patient samples was determined using RT-qPCR. Odds ratios of invasion and metastasis were calculated using logistic regression analysis. Recurrence-free survival was assessed using Cox regression analysis. Scratch wound healing, transwell and tumorigenesis assays were used to determine migration and invasion abilities of retinoblastoma cells in vitro and in vivo. Levels of EMT-related proteins were measured using Western blotting. Binding sites between lnc00152 and its targets were validated using dual-luciferase reporter and RNA pull-down assays. Lnc00152 activating transcription factors were determined using ChIP assays.

RESULTS

We found that Lnc00152 was significantly up-regulated in retinoblastoma tumour tissues, and was a risk factor for tumour invasion, metastasis and recurrence. Lnc00152 overexpressing retinoblastoma cells exhibited a tendency to transform into mesenchymal cells, with significantly increased migration and invasion capacities, significantly decreased E-cadherin expression levels, and significantly increased N-cadherin, SOX9 and ZEB2 expression levels. In addition, we found that lnc00152, which was activated by Sp1, could inhibit miR-30d as an endogenous miRNA 'sponge', thereby regulating the expression of SOX9 and ZEB2.

CONCLUSIONS

Our data indicate that Lnc00152 may be associated with retinoblastoma invasion, metastasis and prognosis. In addition, we conclude that Lnc00152, which can be activated by Sp1, can induce EMT via the miR-30d/SOX9/ZEB2 pathway and, by doing so, promote the invasion and metastasis of retinoblastoma cells.

LncRNA RP1-85F18.6 affects osteoblast cells by regulating the cell cycle

A lncRNA RP1-85F18.6 was reported to affect cell growth by regulating the cell cycle. Here we tested whether it affects the proliferation of osteoblast cells by regulating the cell cycle. We determined the expression of RP1-85F18.6 in two osteoblast cell lines hFOB and HOB by qPCR. Then we knocked down or overexpressed RP1-85F18.6 in hFOB and tested the alteration of viability, cell cycle, and cell cycle regulatory proteins. Results showed that both hFOB and HOB expressed RP1-85F18.6. The knockdown of RP1-85F18.6 decreased the viability of hFOB, while the overexpression of it increased the viability. Higher expression of RP1-85F18.6 results in higher cell viability. The knockdown of RP1-85F18.6 caused an increase in the S phase cells and a decrease in the G2/M phase cells. The overexpression of RP1-85F18.6 caused a decrease in the S phase cells and an increase in the G2/M phase cells. The knockdown of RP1-85F18.6 decreased cyclin A, cdk1, E2F, cyclin B, p53, and p21, whereas the overexpression of RP1-85F18.6 increased cyclin A, cdk1, E2F, cyclin B, p53, and p21. This study demonstrated that RP1-85F18.6 is expressed in osteoblast cell lines hFOB and HOB. RP1-85F18.6 affects the proliferation of osteoblasts by regulating the cell cycle.

Zebrafish xenograft model of human lung cancer for studying the function of LINC00152 in cell proliferation and invasion

Background

Numerous studies have shown that long noncoding RNAs play important roles in human cancer progression. Although zebrafish xenografts have recently become a novel in vivo model for human cancer research, whether such models can be used to study the function of long noncoding RNAs remains unknown.

Methods

In vitro studies validated the roles of LINC00152 in the proliferation and invasion of lung cancer cells. In vivo studies of zebrafish xenografts also confirmed these roles of LINC00152. In vivo confocal imaging was used to more accurately evaluate the function of LINC00152 in cell proliferation and migration. Pharmacological experiments were further performed to study the potential ability of LINC00152 downregulation combined with an EGFR inhibitor to treat tumors in cultured cells and the zebrafish xenograft model.

Results

Silencing of LINC00152 suppressed cell proliferation and invasion in SPCA1 and A549 lung cancer cell lines in vitro. In the zebrafish xenograft model, knockdown of LINC00152 reduced the proliferation and migration of lung cancer cells, as indicated by the two imaging methods at different magnifications. Moreover, the knockdown of LINC00152 enhanced the inhibition effect of afatinib for lung cancer progression in cultured cells and the zebrafish xenograft model.

Conclusion

Our study reveals the oncogenic roles and potential for LINC00152 to be a target for tumor treatment in lung cancer using zebrafish xenograft models, and the findings suggest that this model could be used for functional and application studies of human long noncoding RNAs in tumor biology.

Long non-coding RNA AFAP1-AS1 accelerates the progression of melanoma by targeting miR-653-5p/RAI14 axis

BACKGROUND

Melanoma is the most aggressive skin cancer that derived from pigment cells, accounting for the majority of the skin-cancer-related deaths. Despite great development and evolution have been made in surgery, radiotherapy and adjuvant chemotherapy, the prognosis of melanoma patients exhibited no significant improvement. Long noncoding RNAs (lncRNAs) are frequently dysregulated and involved in the development of cancers. LncRNA AFAP1-AS1 has been explored in various cancers, whereas its role and regulatory mechanism in melanoma are not well understood.

METHODS

The expression of AFAP1-AS1 was detected by qRT-PCR. CCK-8, colony formation, transwell and western blot assays were performed to investigate the biological role of AFAP1-AS1 in melanoma. Male BALB/c nude mice were applied for in vivo experiments. The interaction among AFAP1-AS1, miR-653-5p and RAI14 was investigated by RNA pull down, RIP and luciferase reporter assays.

RESULTS

AFAP1-AS1 was highly expressed in melanoma cell lines. Suppression of AFAP1-AS1 impaired cell proliferation, migration, invasion and EMT in melanoma. Moreover, AFAP1-AS1 was a ceRNA of RAI14 by competitively binding with miR-653-5p. Besides, miR-653-5p overexpression or RAI14 inhibition could repress tumor growth. Eventually, rescue assays indicated that the function of AFAP1-AS1 in the cellular process of melanoma was dependent on miR-653-5p and RAI14.

CONCLUSIONS

AFAP1-AS1 exerts its oncogenic function in melanoma by targeting miR-653-5p/RAI14 axis.

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.

Construction of a competing endogenous RNA network using differentially expressed lncRNAs, miRNAs and mRNAs in non‑small cell lung cancer

The competing endogenous RNA (ceRNA) network is crucial for the development and progression of tumors, including non-small cell lung cancer (NSCLC). However, what type of ceRNA network regulates NSCLC has not been clarified. The present study aimed to elucidate the long non-coding RNA (lncRNA)/microRNA (miRNA)/mRNA ceRNA network in NSCLC, particularly for the significance of lncRNAs in NSCLC. NSCLC-specific differentially expressed lncRNAs, miRNAs and mRNAs in the Cancer Genome Atlas (TCGA) were analyzed and their relationship was analyzed by a ceRNA network. Their potential functions of differentially expressed mRNAs were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, the expression levels of four selected lncRNAs in TCGA were determined and their associated survival of patients was examined. In addition, the expression profiles of these four lncRNAs in 48 NSCLC specimens and cell lines, their cellular distribution and associated clinical parameters were examined. We successfully constructed a ceRNA network, including 113 lncRNAs, 12 miRNAs and 36 mRNAs differentially expressed between NSCLC and non-tumor tissues. LINC00525, MED4-AS1, STEAP2-AS1 and SYNPR-AS1 lncRNAs were selected and validated for their association with the survival of NSCLC patients. The expression of these lncRNAs was upregulated in 48 NSCLC tissues and was varying in NSCLC cells. While LINC00525 was mainly expressed in the cytoplasm, MED4-AS1 was in both the nucleus and cytoplasm of A549 cells. In addition, the expression of LINC00525 was significantly associated with smoking history (P<0.05); MED4-AS1 was significantly associated with women, poor differentiation and lymph node metastasis (P<0.05); STEAP2-AS1 was significantly associated with women (P<0.01); and SYNPR-AS1 was significantly associated with women and adenocarcinoma (P<0.05). These lncRNAs may be valuable biomarkers for prognosis of NSCLC and the ceRNA network may provide new insights in the pathogenesis of NSCLC.

Identify CRNDE and LINC00152 as the key lncRNAs in age-related degeneration of articular cartilage through comprehensive and integrative analysis

Background

Osteoarthritis (OA) is one of the most important age-related degenerative diseases, and the leading cause of disability and chronic pain in the aging population. Recent studies have identified several lncRNA-associated functions involved in the development of OA. Because age is a key risk factor for OA, we investigated the differential expression of age-related lncRNAs in each stage of OA.

Methods

Two gene expression profiles were downloaded from the GEO database and differentially expressed genes (DEGs) were identified across each of the different developmental stages of OA. Next, gene ontology (GO) functional and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to annotate the function of the DEGs. Finally, a lncRNA-targeted DEG network was used to identify hub-lncRNAs.

Results

A total of 174 age-related DEGs were identified. GO analyses confirmed that age-related degradation was strongly associated with cell adhesion, endodermal cell differentiation and collagen fibril organization. Significantly enriched KEGG pathways associated with these DEGs included the PI3K–Akt signaling pathway, focal adhesion, and ECM–receptor interaction. Further analyses via a protein–protein interaction (PPI) network identified two hub lncRNAs, CRNDE and LINC00152, involved in the process of age-related degeneration of articular cartilage. Our findings suggest that lncRNAs may play active roles in the development of OA. Investigation of the gene expression profiles in different development stages may supply a new target for OA treatment.

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.